Patent Application
20230312842
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2022-017985 filed Feb. 8, 2022 and Japanese Patent Application No. 2022-122215 filed Jul. 29, 2022.
The present disclosure relates to a cellulosic particle.
In Japanese Patent No. 6872068, “resin beads formed of a resin containing cellulose as a main component, wherein the particle size at a cumulative percentage of 50% in terms of volume is 50 µm or less, the sphericity is 0.7-1.0, the surface smoothness is 70-100%, the solidity is 50-100%, the five-day biodegradability measured according to JIS K6950:2000 (ISO 14851:1999) is 20% or greater, and the content of cellulose in the resin is 90-100 mass%.” are proposed.
In Japanese Patent No. 6855631, “a powdered cellulose which has a mean particle diameter of 5 to 150 µm, and an in-water sonication residual ratio of 20 to 60%, the in-water sonication residual ratio (%) represented by [particle diameter at 50% cumulative total volume by wet method measurement (with ultrasound irradiation) / particle diameter at 50% cumulative total volume by wet method measurement (without ultrasound irradiation)] × 100.” is proposed.
Aspects of non-limiting embodiments of the present disclosure relate to a cellulosic particle that may be highly biodegradable and exhibit little change in texture over time compared with cellulosic particles containing cellulose as their base constituent and whose 5-day or 60-day percentage biodegradation measured as per JIS K6950:2000 exceeds 20% or is lower than 60%, respectively.
Aspects of certain non-limiting embodiments of the present disclosure address the above advantages and/or other advantages not described above. However, aspects of the non-limiting embodiments are not required to address the advantages described above, and aspects of the non-limiting embodiments of the present disclosure may not address advantages described above.
According to an aspect of the present disclosure, there is provided a cellulosic particle containing cellulose as a base constituent, wherein 5-day and 60-day percentage biodegradations of the cellulosic particle measured as per JIS K6950:2000 are lower than 20% and 60% or higher, respectively.
Exemplary embodiments of the present disclosure will now be described. The following description and the Examples are for illustrating exemplary embodiments and do not limit the scope of aspects of the present disclosure.
In a series of numerical ranges presented herein, the upper or lower limit of a numerical range may be substituted with that of another in the same series. The upper or lower limit of a numerical range, furthermore, may be substituted with a value indicated in the Examples section.
A constituent may be a combination of multiple substances.
If a composition contains a combination of multiple substances as one of its constituents, the amount of the constituent represents the total amount of the substances in the composition unless stated otherwise.
Cellulosic particles according to an exemplary embodiment contain cellulose as their base constituent, and the 5-day and 60-day percentage biodegradations of the cellulosic particles measured as per JIS K6950:2000 are lower than 20% and 60% or higher, respectively.
Configured as described above, the cellulosic particles according to this exemplary embodiment may be highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
Due to the issue of marine debris, there is a need for biodegradable resin particles. In particular, cellulosic particles containing cellulose as their base constituent have been used in various practical applications, such as cosmetics, by virtue of their rapid biodegradation in all of compost, activated sludge, and seawater environments.
Known cellulosic particles, however, are decomposed too rapidly in the initial stage of biodegradation; the associated decrease in the mechanical strength of the surface of the particles causes chipping and other defects, resulting in the surface texture (feel of the surface when touched, such as smoothness, moist sensation, and softness) of the particles deteriorating over time even under normal use conditions.
Usually, the biodegradation of cellulosic particles starts at the surface of the particles (the point of contact with the degrading medium). Cellulosic particles with high initial biodegradability, therefore, experience a decrease in the molecular weight of cellulose specifically on their very surface. The resulting decrease in the strength of the surface makes the particles more prone to minor chipping and deformation. Limiting the initial biodegradability of cellulosic particles may help control the chipping and deformation of the surface of the particles that occur over time, and this may help reduce changes in the texture of the particles over time.
More specifically, making the 5-day percentage biodegradation of cellulosic particles measured as per JIS K6950:2000 lower than 20% may lead to reduced initial biodegradability of the particles. This may help reduce changes in the texture of the particles over time by helping control the chipping and deformation of the surface of the particles over time.
Making the 60-day percentage biodegradation of the cellulosic particles measured as per JIS K6950:2000 equal to or higher than 60%, furthermore, may ensure that the particles remain highly biodegradable.
For these reasons, presumably, the cellulosic particles according to this exemplary embodiment, configured as described above, may be highly biodegradable and exhibit little change in texture over time.
Specifically, the cellulosic particles according to this exemplary embodiment may exhibit little change in their feel when touched, such as smoothness, moist sensation, and softness, by virtue of the small changes in their texture over time.
The details of the cellulosic particles according to this exemplary embodiment will now be described.
The cellulosic particles according to this exemplary embodiment contain cellulose as their base constituent.
In this context, the term containing cellulose as a base constituent (or “cellulose-based”) means the cellulose content of the cellulosic particles is 90% by mass or more.
If the cellulosic particles have a coating layer as described later herein, containing cellulose as a base constituent (or cellulose-based) means the cellulose content of the core particle is 90% by mass or more.
The number-average molecular weight of the cellulose may be 37000 or more, preferably 45000 or more.
There is no particular upper limit, but for example, the number-average molecular weight of the cellulose may be 100000 or less.
Making the number-average molecular weight of the cellulose 37000 or more may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
If the number-average molecular weight of the cellulose is too low, the initial rate of biodegradation tends to be out of control because of too rapid biodegradation. Making the molecular weight 37000 or more may help reduce changes in texture over time by helping control the chipping and deformation of the surface of the particles. If the number-average molecular weight is too low, furthermore, the disintegration of the particles is somewhat nonuniform because of too rapid initial biodegradation; the resulting variations in size between particles will lead to a slow overall rate of biodegradation. Making the molecular weight 37000 or more may help ensure uniform disintegration, and therefore superior biodegradability, of the particles.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
The number-average molecular weight of the cellulose is measured by gel permeation chromatography (differential refractometer, Optilab T-rEX, Wyatt Technology; multiangle light scattering detector, DAWN HELEOS II, Wyatt Technology; columns, one TSKgel α-M and one α-3000, Tosoh) with dimethylacetamide eluent (containing 0.1 M lithium chloride).
The cellulosic particles according to this exemplary embodiment may contain extra constituents. If the cellulosic particles have a coating layer as described later herein, the extra constituents are contained in the core particle, covered with the coating layer.
Examples of extra constituents include plasticizers, flame retardants, compatibilizers, release agents, light stabilizers, weathering agents, coloring agents, pigments, modifiers, anti-dripping agents, antistatic agents, anti-hydrolysis agents, fillers, reinforcing agents (glass fiber, carbon fiber, talc, clay, mica, glass flakes, milled glass, glass beads, crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, etc.), acid acceptors for preventing acetic acid release (oxides, such as magnesium oxide and aluminum oxide; metal hydroxides, such as magnesium hydroxide, calcium hydroxide, aluminum hydroxide, and hydrotalcite; calcium carbonate; talc; etc.), and reactive trapping agents (e.g., epoxy compounds, acid anhydride compounds, carbodiimides, etc.).
The amount of each extra constituent may be 0% by mass or more and 5% by mass or less of the cellulosic particles (or core particles) as a whole. In this context, “0% by mass” means the cellulosic particles (or core particles) are free of that extra constituent.
The 5-day percentage biodegradation of the cellulosic particles according to this exemplary embodiment measured as per JIS K6950:2000 is lower than 20%. For the reduction of changes in texture over time, the 5-day percentage biodegradation may be 15% or lower, preferably 10% or lower.
The 5-day percentage biodegradation may ideally be 0%, but it is difficult to completely eliminate initial biodegradability because the material used is biodegradable by nature; therefore, the 5-day percentage biodegradation is, for example, 5% or higher.
The 60-day percentage biodegradation of the cellulosic particles according to this exemplary embodiment measured as per JIS K6950:2000 is 60% or higher. For high biodegradability, the 60-day percentage biodegradation may be 65% or higher, preferably 70% or higher.
Higher 60-day percentage biodegradations may be better, but usually, this percentage cannot be 100%, for example because of limited precision in measuring the BOD, or precision in the detection of oxygen, and the influence of oxygen consumption by microorganisms not involving the decomposition of the sample; therefore, the 60-day percentage biodegradation is, for example, 95% or lower.
These percentage biodegradations are measured as per JIS K6950:2000. JIS K6950:2000 corresponds to ISO 14851:1999.
Specifically, the percentage biodegradations are calculated from the oxygen demands of the cellulosic particles of interest (hereinafter, the test substance) and a reference substance according to the equation below.
The oxygen demands, furthermore, are measured using a closed-system oxygen consumption meter under the following conditions.
The cellulosic particles according to this exemplary embodiment may be cellulosic particles having a cellulose-based core particle (hereinafter also referred to as a cellulosic core particle) and a coating layer covering the core particle and containing at least one selected from the group consisting of a polyamine compound, an arginine compound, a wax, a linear-chain fatty acid, a linear-chain fatty acid metallic salt (metallic salt of a linear-chain fatty acid), a hydroxy fatty acid, and an amino acid compound (hereinafter also referred to as “coated cellulosic particles”).
This configuration may make more certain that the cellulosic particles according to this exemplary embodiment are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
A polyamine compound adheres to the surface of the cellulose with its affinity for hydroxyl groups. The adhesion of the polyamine compound, therefore, may help control initial biodegradation of the surface of the cellulosic particles, and this may help reduce changes in texture over time. The polyamine compound, furthermore, does not cover the surface completely but leaves portions of the surface exposed. Since microorganisms can pass through the spaces left on the surface, the superior biodegradability of the cellulose may be reflected in that of the particles after time.
An arginine compound covers part of the cellulosic core particle through ionic bonding between its terminal carboxylic acid and hydroxyl groups on the surface of the cellulosic core particle. It appears that a seamless array of exposed portions and portions covered with the arginine compound is formed on the cellulosic core particle, and the resulting delicate irregularities and unevenness in hygroscopic capacity may help reduce changes in texture over time. Although initial biodegradation is limited because the covered portions are less biodegradable than the cellulosic core particle itself, the entire particles may biodegrade after time because the arginine compound is also biodegradable.
A wax, a linear-chain fatty acid, and a linear-chain fatty acid metallic salt, highly water-repellent in themselves, may inhibit the hydrolysis of the cellulose by making the particles more hydrophobic, and the uniform progress of the biodegradation of the particles without surface chipping in the initial stage of biodegradation enabled by this may help reduce changes in texture over time. These compounds may also help achieve superior biodegradability; they leave exposed portions on the surface of the core particle with their tendency to partial aggregation, providing spaces for microorganisms to penetrate through.
A hydroxy fatty acid adheres to the surface of the cellulosic particles through weak hydrogen bonding between its hydroxyl group and hydroxyl groups of the cellulosic particles. The fatty acid moiety of the adhering hydroxy fatty acid, facing outwards from the particle, may inhibit initial hydrolysis of the cellulose by improving the hydrophobicity of the particle, and the inhibited initial hydrolysis of the cellulose may help reduce changes in texture over time by preventing surface chipping. The hydrocarbon moiety of the fatty acid, furthermore, is spaced apart from the cellulose because of its low affinity for cellulose; microorganisms can penetrate into the cellulosic particles through the spaces, and the uniform progress of biodegradation enabled by this may help achieve superior biodegradability.
An amino acid compound has a strong tendency to form flat-shaped crystals after coating; these crystals may help limit initial contact between microorganisms and the cellulose with their large specific surface area, and the resulting delayed biodegradation may lead to reduced changes in texture over time. The crystals, furthermore, are formed with spaces therebetween, through which microorganisms can penetrate slowly; the resultant uniform progress of biodegradation may help achieve superior biodegradability.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
Incidentally, the cellulosic particles according to this exemplary embodiment may have a cellulose-based core particle produced by, for example, saponifying a cellulose acylate to have more hydroxyl groups on its surface than inside. This may help cover the core particle with the coating layer with a high coverage.
Cosmetics made with the coated cellulosic particles, furthermore, may produce superior skin feelings (smoothness, moist sensation, and softness) even at high or low temperatures. Possible reasons are as follows.
The biodegradation of coated cellulosic particles is initiated by one or both of the following two events.
Degrading microorganisms pass through the coating layer and biodegrade the cellulosic core particle, which rapidly biodegrades by nature.
Microorganisms decompose the coating layer itself.
If the 5-day percentage biodegradation measured as per JIS K6950 (ISO 14581:1999) is as high as 20% or higher, what drives the process is event (1), the decomposition of the rapidly biodegradable cellulosic core particle. Under normal temperature conditions, biodegradation would not affect the feelings the particles produce on the skin in cosmetic use, because the structure of the coating layer would remain. The surface of the cellulosic core particle, however, would be decomposed, and the coating layer would lose a ground for it to lie on; part of it would no longer be bound to the surface of the cellulosic core particle.
At low ambient temperatures of 0° C. or below, the coating layer becomes brittle because molecular motions in its structure are frozen. Even in this situation, the structure of the coating layer is not broken as long as the coating layer is sticking to the cellulosic core particle, because the cellulosic core particle is strong even at low temperatures.
Since the 5-day percentage biodegradation of the cellulosic particles having a surface layer measured as per JIS K6950 (ISO 14581:1999) is as high as 20% or higher, however, part of the structure of the surface layer is not bound to the cellulosic particles; the structure of the surface layer breaks, starting from the detached portions.
In this way, low temperatures of 0° C. or below affect the feelings the cellulosic particles having a surface layer produce on the skin in cosmetic use (specifically, smoothness, moist sensation, softness, etc.), if the 5-day percentage degradation of the particles measured as per JIS K6950 (ISO 14581:1999) is as high as 20% or higher.
At high ambient temperatures of 60° C. or above, the structure of the coating layer deforms easily. If the coating layer is bound uniformly to the cellulosic core particle, the impact of the deformation is minimal; if the 5-day percentage degradation measured as per JIS K6950 (ISO 14581:1999) is as high as 20% or higher, however, the deformation affects the feelings the coated cellulosic particles produce on the skin in cosmetic use (specifically, smoothness, moist sensation, softness, etc.) because part of the structure of the coating layer is not bound to the cellulosic core particle.
If the 60-day percentage biodegradation measured as per JIS K6950 (ISO 14581:1999) is lower than 60%, the cellulosic core particle is totally inaccessible by microorganisms, for example in a form like the surface of the cellulosic particles is densely covered with a slowly biodegradable compound, and if such cellulosic particles are placed at low temperatures of 0° C. or below or high temperatures of 60° C. or above, their surface layer cracks due to the difference in linear expansion between it and the cellulosic core particle, making the surface very rough. This affects the feelings the cellulosic particles produce on the skin in cosmetic use (specifically, smoothness, moist sensation, softness, etc.).
For these reasons, presumably, cosmetics made with the coated cellulosic particles may produce superior skin feelings (smoothness, moist sensation, and softness) even at high or low temperatures.
The core particle is a cellulose-based particle.
The cellulose contained in the core particle has the same definition as the cellulose previously described herein; possible and preferred ranges of parameters are also the same as in the foregoing.
The coating layer contains at least one selected from the group consisting of a polyamine compound, a wax, an arginine compound, a linear-chain fatty acid, a linear-chain fatty acid metallic salt (metallic salt of a linear-chain fatty acid), a hydroxy fatty acid, and an amino acid compound.
“Polyamine compound” is a generic term for aliphatic hydrocarbons having two or more primary amino groups.
Examples of polyamine compounds include a polyalkyleneimine, polyallylamine, polyvinylamine, and polylysine.
For improved biodegradability, the polyalkyleneimine may be a polyalkyleneimine including a repeat unit having an alkylene group with one or more and six or fewer carbon atoms (C1 to C6; preferably C1 to C4, more preferably C1 or C2), preferably polyethyleneimine.
Examples of polyallylamines include homopolymers or copolymers of allylamine, allylamine amidosulfate, diallylamine, dimethylallylamine, etc.
Examples of polyvinylamines include products of alkali hydrolysis of poly(N-vinylformamide); a specific example is Mitsubishi Chemical’s “PVAM-0595B.”
The polylysine may be an extract from a natural source, may be a substance produced by a transformed microorganism, or may be a product of chemical synthesis.
The polyamine compound may be at least one selected from the group consisting of polyethyleneimine and polylysine.
Using at least one selected from the group consisting of polyethyleneimine and polylysine as polyamine compound(s) may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
Polyethyleneimine and polylysine are able to adhere firmly to the cellulosic particles by virtue of their high cation density and functional groups that react with the hydroxyl groups in the cellulose. Their hydrocarbon chain, at the same time, takes up an appropriate relative area, so if they adhere to the surface of the cellulosic particles, the hydrocarbon chains tend to be exposed on the surface; the resulting increase in the hydrophobicity of the particles may prevent surface defects by slowing down initial hydrolysis and biodegradation of the cellulose, and the uniform progress of biodegradation enabled by this may reduce changes in texture over time. Polyethyleneimine and polylysine, furthermore, are not dense but relatively loose in terms of structure, which means that they provide spaces for microorganisms to penetrate through; the superior biodegradability of the cellulose, therefore, may be reflected in that of the particles.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
The polyamine compound content may be 0.2% by mass or more and 2% by mass or less of the cellulosic particles as a whole.
Arginine compounds are compounds having the structure of 2-amino-5-guanidinopentanoic acid (2-amino-5-guanidinovaleric acid).
Examples of arginine compounds include L-arginine, D-arginine, 2-amino-3-methyl-5-guanidinopentanoic acid, 2-amino-3-ethyl-5-guanidinopentanoic acid, and 2-amino-3,3-dimethyl-5-guanidinopentanoic acid.
The arginine compound content may be 0.1% by mass or more and 5% by mass or less of the cellulosic particles as a whole.
Examples of waxes include fatty acid-containing vegetable oils, hydrocarbon waxes, and diesters.
Examples of fatty acid-containing vegetable oils include castor oil, paulownia oil, linseed oil, shortening, corn oil, soybean oil, sesame oil, rapeseed oil, sunflower oil, rice bran oil, camellia oil, coconut oil, palm oil, walnut oil, olive oil, peanut oil, almond oil, jojoba oil, cocoa butter, shea butter, neem oil, safflower oil, Japan wax, candelilla wax, rice bran wax, carnauba wax, and Rosa damascena flower wax.
Examples of hydrocarbon waxes include petroleum waxes (paraffin wax, microcrystalline wax, petrolatum wax, etc.) and synthetic hydrocarbon waxes (polyethylene wax, polypropylene wax, polybutene wax, Fischer-Tropsch wax, etc.).
Examples of diesters include diesters of dibasic acids, such as malic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid, and C10 to C25 alcohols.
The wax may be carnauba wax.
Using carnauba wax as a wax may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
Carnauba wax may be highly effective in reducing changes in texture over time because constituents having a water-repellent structure abundant therein, such as free fatty acids and hydrocarbons, may help prevent initial hydrolysis of the cellulosic particles and may enable uniform progress of biodegradation without surface chipping; carnauba wax, furthermore, may help achieve superior biodegradability if enough time is allowed, because it adheres to the cellulosic particles through weak hydrogen bonding between free alcohols it contains and hydroxyl groups of the cellulosic particles, but with spaces at the interface through which microorganisms can penetrate by virtue of relatively weak adhesive strength.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
The wax content may be 0.1% by mass or more and 2% by mass or less, preferably 0.2% by mass or more and 1% by mass or less, of the cellulosic particles as a whole.
Linear-chain fatty acids are saturated or unsaturated fatty acids in a linear-chain structure. The linear-chain fatty acid may be a mixture of saturated and unsaturated fatty acids.
For improved biodegradability and smaller changes in texture over time, the linear-chain fatty acid may be a C14 to C22 linear-chain fatty acid. Specific examples of C14 to C22 linear-chain fatty acids include behenic acid, arachidic acid, and palmitic acid.
The reason why using a linear-chain fatty acid in the coating layer may help reduce changes in the texture of the particles over time and achieve superior biodegradability appears to be as follows. The terminal carboxylic acid is able to adhere to the surface of the cellulosic particles by forming covalent bonds with, or by virtue of its ionic affinity for, hydroxyl groups of the cellulose. On the surface, linear-chain hydrocarbon groups are exposed and may inhibit the hydrolysis of the cellulose by making the particles more hydrophobic, and the uniform progress of the biodegradation of the particles without surface chipping in the initial stage of biodegradation enabled by this may help reduce changes in texture over time. This compound, furthermore, may help achieve superior biodegradability because it creates a porous portion on the surface because of its tendency to partial aggregation, and microorganisms can penetrate into the particles through spaces in this portion.
If the number of carbon atoms in the linear-chain fatty acid is 14 or more, the effectiveness of the fatty acid in preventing changes in texture over time and the biodegradability of the particles may both be sufficiently high because in that case the partial aggregation of the fatty acid may be sufficiently strong. If the number of carbon atoms is 22 or fewer, however, the linear-chain fatty acid tends to be insufficiently effective in preventing changes in texture over time; in that case, the weakening of its adhesion to the surface of the cellulosic particles is limited because the aggregation of the fatty acid in unlikely to be strong.
The linear-chain fatty acid content may be 2% by mass or more and 15% by mass or less, preferably 5% by mass or more and 10% by mass or less, of the cellulosic particles as a whole.
A linear-chain fatty acid metallic salt is a metallic salt of a linear-chain saturated or unsaturated fatty acid. The linear-chain fatty acid metallic salt may be a mixture of metallic salts of saturated and unsaturated fatty acids.
Examples of fatty acid metallic salts include metallic salts of C10 to C25 (preferably C12 to C22) fatty acids. Examples of metallic salts of C10 to C25 fatty acids include metallic salts of stearic acid, palmitic acid, lauric acid, oleic acid, linoleic acid, and ricinoleic acid.
An example of a metal in a linear-chain fatty acid metallic salt is a divalent metal. Examples of metals in linear-chain fatty acid metallic salts include magnesium, calcium, aluminum, barium, and zinc.
The linear-chain fatty acid metallic salt content may be 2% by mass or more and 15% by mass or less, preferably 5% by mass or more and 10% by mass or less, of the cellulosic particles as a whole.
For improved biodegradability and smaller changes in texture over time, the hydroxy fatty acid may be a C12 to C20 hydroxy fatty acid.
Examples of C12 to C20 hydroxy fatty acids include hydroxystearic acid, hydroxypalmitic acid, hydroxylauric acid, hydroxymyristic acid, and hydrogenated castor oil fatty acids.
The reason why using a hydroxy fatty acid in the coating layer may help prevent changes in the texture of the particles over time and achieve superior biodegradability appears to be as follows. The hydroxy fatty acid adheres to the surface of the cellulosic particles through weak hydrogen bonding between its hydroxyl group and hydroxyl groups of the cellulosic particles. The fatty acid moiety of the adhering hydroxy fatty acid, facing outwards from the particle, may inhibit initial hydrolysis of the cellulose by improving hydrophobicity, and the inhibited initial hydrolysis of the cellulose may help reduce changes in texture over time by preventing surface chipping. The hydrocarbon moiety of the fatty acid, furthermore, is spaced apart from the cellulose because of its low affinity for cellulose; microorganisms can penetrate into the cellulosic particles through the spaces, and the uniform progress of biodegradation enabled by this may help achieve superior biodegradability.
If the number of carbon atoms in the hydroxy fatty acid is 12 or more, the effectiveness of the fatty acid in reducing changes in texture over time may tend to be improved because in that case it may be unlikely that the repulsion between molecules of the fatty acid is weak, and, therefore, hydrophobicity may be improved. In the opposite case, or if the number of carbon atoms is 20 or fewer, biodegradability may tend to be improved because in that case it may be unlikely that long chains of the fatty acid become entangled together, and, therefore, the associated blockage of pathways for microorganisms to enter through may be reduced.
The hydroxy fatty acid content may be 1% by mass or more and 10% by mass or less, preferably 3% by mass or more and 10% by mass or less, of the cellulosic particles as a whole.
“Amino acid compounds” refers to amino acids and amino acid derivatives.
Examples of amino acid compounds include lauryl leucine, lauryl arginine, and myristyl leucine.
The reason why using an amino acid compound in the coating layer may help prevent changes in the texture of the particles over time and achieve superior biodegradability appears to be as follows. An amino acid compound has a strong tendency to form flat-shaped crystals after coating; these crystals may help limit initial contact between microorganisms and the cellulose with their large specific surface area, and the resulting delayed biodegradation may lead to reduced changes in texture over time. The crystals, furthermore, are formed with spaces therebetween, through which microorganisms can penetrate slowly; the resultant uniform progress of biodegradation may help achieve superior biodegradability.
The amino acid compound content may be 2% by mass or more and 10% by mass or less of the cellulosic particles as a whole.
The coating layer may have a first coating layer covering the core particle and containing at least one selected from the group consisting of a polyamine compound, polyvinyl alcohol, polyvinylpyrrolidone, and an arginine compound and a second coating layer covering the first coating layer and containing at least one selected from the group consisting of a wax, a linear-chain fatty acid, a linear-chain fatty acid metallic salt, a hydroxy fatty acid, and an amino acid compound.
In particular, the coating layer may have a first coating layer covering the core particle and containing at least one selected from the group consisting of a polyamine compound, an arginine compound, a linear-chain fatty acid, a hydroxy fatty acid, and an amino acid compound and a second coating layer covering the first coating layer and containing at least one selected from the group consisting of a wax, a linear-chain fatty acid, a linear-chain fatty acid metallic salt, a hydroxy fatty acid, and an amino acid compound. The first and second coating layers, however, contain different compound(s).
The presence of such first and second coating layers in the coating layer may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
A wax is highly water-repellent and produces strong repulsive forces, but its tendency to self-aggregate often results in the formation of large defects in the coating layer. If these defects are too large, the effectiveness of the coating layer in inhibiting the hydrolysis of the cellulose can be affected, causing chipping of the surface of the particles that can make the reduction of changes in texture over time less significant. Coating the surface with a certain amount of the wax may help prevent the formation of defects, but too much wax, in turn, tends to affect biodegradability. A linear-chain fatty acid and a fatty acid metallic salt tend to be highly crystallizable depending on factors such as ambient temperature, and once crystallized, they can lose some of their adhesiveness to the cellulosic core particle; coating the surface with a certain amount of the fatty acid or metallic salt may help prevent this, but too much fatty acid or metallic salt, in turn, tends to affect biodegradability.
A polyamine compound, hydroxy fatty acid, amino acid compound, or arginine compound only produces weaker repulsive forces than a wax, but its high adhesiveness to the cellulosic particles may help reduce defects in the coating layer. A polyamine compound, a linear-chain fatty acid, a hydroxy fatty acid, and an amino acid compound, furthermore, adhere firmly to a wax, and vice versa; using such a compound, therefore, may discourage the formation of coating defects that occur when a wax is used.
For these reasons, the presence of first and second coating layers as described above in the coating layer may make more certain that the cellulosic particles exhibit little change in texture over time. Even if it is a bilayer one, the coating layer still has spaces in it for microorganisms to slowly penetrate through; the biodegradation process, therefore, may proceed more uniformly, and this may help achieve superior biodegradability.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
Cosmetics made with the cellulosic particles whose coating layer has such first and second coating layers, furthermore, may produce superior skin feelings (smoothness, moist sensation, and softness) even at high or low temperatures. Possible reasons are as follows.
The second coating compound(s) may be effective for smoothness and softness by virtue of its high hydrophobicity and water repellency. As for moist sensation, the compound(s) tends to be somewhat detrimental to the hygroscopicity and water retention of the cellulosic core particle. The first coating layer may be able to tie the cellulosic core particle and the second coating layer firmly together by virtue of its compatibility with and ability to bind with both the cellulosic core particle and the first coating layer. The resulting strong influence of the hygroscopicity and water retention of the cellulosic core particle on the second coating layer may help improve moist sensation, too.
In particular, the coating layer may have a first coating layer covering the core particle and containing at least one selected from the group consisting of a polyamine compound and an arginine compound and a second coating layer covering the first coating layer and containing at least one selected from the group consisting of a linear-chain fatty acid, a linear-chain fatty acid metallic salt, and an amino acid compound so that cosmetics made with the cellulosic particles may produce superior skin feelings (smoothness, moist sensation, and softness) even at high or low temperatures. Possible reasons are as follows.
A linear-chain fatty acid and a linear-chain fatty acid metallic salt, having a fatty acid moiety that may provide superior hydrophobicity and water repellency, tend to undergo ionic bonding with the cellulosic core particle with their carboxylic acid or carboxylic acid metallic salt moiety, and the resulting concentration of the linear-chain fatty acid moiety in the position closer to the surface of the cellulosic core particle may lead to improved smoothness and softness. An amino acid compound has only a short aliphatic length, but its terminal amino acid binds with the first coating layer very firmly; the short aliphatic, therefore, gathers on the surface and may improve smoothness and softness. Using a polyamine compound or arginine compound in the first coating layer, furthermore, may help make the cellulosic particles superior in all of skin feelings, smoothness, moist sensation, and softness because these compounds may have a particularly powerful effect in keeping the second and first coating layers close to each other yet may be harmless to the moist sensation of the cellulosic core particle; a polyamine compound has an amino group at both ends, and one of them binds firmly with hydroxyl groups on the cellulosic core particle with the other binding firmly with carboxylic or amino acid(s) on the second coating layer; an arginine compound has a terminal amino acid that binds with hydroxyl groups of the cellulose and a guanidine structure that binds with carboxylic or amino acid(s) on the second coating layer.
The second coating layer may contain a polyvalent metal salt.
The presence of a polyvalent metal salt in the second coating layer may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. A possible reason is as follows.
A wax contained in the second layer adheres to the layer beneath it only weakly. The resulting coating, therefore, tends to easily have defects as a result of self-aggregation of the wax. If a polyvalent metal is contained in the second coating layer together with the wax, the polyvalent metal salt spreads uniformly throughout the wax, providing starting points for the wax to aggregate uniformly and extensively; this may limit the formation of defects in the coating caused by the self-aggregation of the wax and encourage the adhesion of the second coating layer.
For this reason, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
Polyvalent metal salts are compounds formed by a divalent or higher-valency metal ion and an anion.
Examples of divalent or higher-valency metal ions as a component of a polyvalent metal salt include the ions of calcium, magnesium, copper, nickel, zinc, barium, aluminum, titanium, strontium, chromium, cobalt, iron, etc.
Examples of anions as a component of a polyvalent metal salt include inorganic or organic ions. Examples of inorganic ions include the chloride, bromide, iodide, nitrate, sulfate, and hydroxide ions. Examples of organic ions include organic acid ions, such as the carboxylate ion.
Examples of polyvalent metal salts include aluminum sulfate, polyaluminum chloride, iron chloride, and calcium hydroxide.
The polyvalent metal salt content in relation to the total amount of the wax, linear-chain fatty acid, linear-chain fatty acid metallic salt, hydroxy fatty acid, and amino acid compound may be 0.1% by mass or more and 10% by mass or less, preferably 0.2% by mass or more and 5% by mass or less, even more preferably 0.3% by mass or more and 1% by mass or less.
The total amount of the polyamine compound, polyvinyl alcohol, polyvinylpyrrolidone, arginine compound, linear-chain fatty acid, hydroxy fatty acid, and amino acid compound in relation to the entire first coating layer may be 90% by mass or more and 100% by mass or less, preferably 95% by mass or more and 100% by mass or less.
The total amount of the wax, linear-chain fatty acid, linear-chain fatty acid metallic salt, hydroxy fatty acid, amino acid compound, and polyvalent metal salt in relation to the entire second coating layer may be 90% by mass or more and 100% by mass or less, preferably 95% by mass or more and 100% by mass or less.
The cellulosic particles according to this exemplary embodiment may have at least one external additive selected from the group consisting of silicon-containing compound particles, metallic soap particles, fatty acid ester particles, and metal oxide particles.
In particular, the cellulosic particles according to this exemplary embodiment may have at least one external additive selected from the group consisting of silicon-containing compound particles and metallic soap particles.
The presence of such external additive(s) may make more certain that the cellulosic particles according to this exemplary embodiment are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
Silicon-containing compound particles and metallic soap particles are able to adhere to particles larger than themselves by electrostatic adhesion and have a lower surface energy than likewise adhesive metal oxide particles and fatty acid ester particles; silicon-containing compound particles and metallic soap particles, therefore, may be highly effective in improving texture. Even if some of the silicon-containing compound particles and/or metallic soap particles detach from the cellulosic particles, therefore, the associated texture loss may be minor, and this may lead to smaller changes in texture over time. These particles provide plenty of spaces for microorganisms to penetrate through by virtue of their particular shape, so that the superior biodegradability of the cellulose may be preserved.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
“Silicon-containing compound particles” refers to particles containing silicon.
The silicon-containing compound particles may be particles of silicon or may be particles containing silicon and other element(s).
The silicon-containing compound particles may be silica particles.
The silica particles can be any silica-based, or SiO2-based, particles, whether crystalline or amorphous. The silica particles, furthermore, may be particles produced from a raw-material silicon compound, such as waterglass or an alkoxysilane, or may be particles obtained by crushing quartz.
Using silica particles as silicon-containing compound particles may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. A possible reason is as follows.
Silica adheres to the cellulosic particles by electrostatic adhesion particularly firmly and has a particularly low surface energy; the use of silica, therefore, may lead to dramatically reduced changes in texture over time and superior biodegradability for the reasons described above.
For this reason, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
Metallic soap particles are metallic soap-based particles.
In this context, “metallic soap-based particles” refers to particles containing 90% by mass or more metallic soap in relation to the particles themselves.
A metallic soap is a fatty acid metallic salt (metallic salt of a fatty acid), formed by a fatty acid and a metal bound together.
An example of a fatty acid metallic salt is a metallic salt of a C10 to C25 (preferably C12 to C22) fatty acid. Examples of metallic salts of C10 to C25 fatty acids include metallic salts of stearic acid, palmitic acid, lauric acid, oleic acid, linoleic acid, and ricinoleic acid.
An example of a metal in a fatty acid metallic salt is a divalent metal.
Examples of metals in fatty acid metallic salts include magnesium, calcium, aluminum, barium, and zinc.
Fatty acid ester particles are particles including fatty acid ester particles as a base component.
In this context, “particles including fatty acid ester particles as a base component” refers to particles including 90% by mass or more fatty acid ester particles in relation to the particles themselves.
An example of a fatty acid ester is the product of esterification between a C10 to C25 saturated fatty acid and a C10 to C25 alcohol.
Examples of fatty acid esters include stearyl stearate, stearyl laurate, and stearyl palmitate.
Metal oxide particles are metal oxide-based particles.
In this context, “metal oxide-based particles” refers to particles containing 90% by mass or more metal oxide in relation to the particles themselves.
The metal oxide can be an oxide of a metal other than silicon.
Examples of metal oxides include zinc oxide, magnesium oxide, iron oxide, and aluminum oxide.
For texture (specifically, feel when touched) reasons, the volume-average particle diameter of the external additive may be 1 nm or more and 100 nm or less, preferably 5 nm or more and 30 nm or less.
The volume-average particle diameter of the external additive is measured in the same way as that of the cellulose.
The amount of the external additive may be 0.1% by mass or more and 2% by mass or less of the mass of the cellulosic particles (without the external additive) as a whole. Volume-Average Particle Diameter and Upper Geometric Standard Deviation by Number GSDv
The volume-average diameter of the cellulosic particles according to this exemplary embodiment may be 3 µm or more and less than 10 µm, preferably 4 µm or more and 9 µm or less, more preferably 5 µm or more and 8 µm or less.
Making the volume-average diameter of the cellulosic particles according to this exemplary embodiment 3 µm or more and less than 10 µm may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
If the volume-average particle diameter is 3 µm or more, the surface area of the particles is not too large; in that case the particles may have good texture and may be less prone to the impact of surface chipping, and, therefore, the changes in texture over time may be smaller. If the volume-average particle diameter is less than 10 µm, furthermore, the biodegradation process, which starts at the surface, tends to proceed uniformly by virtue of a moderately large surface area; the cellulosic particles, therefore, may tend to be superior in biodegradability.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
The upper geometric standard deviation by number GSDv of the cellulosic particles according to this exemplary embodiment may be 1.0 or greater and 1.7 or less, preferably 1.0 or greater and 1.5 or less, more preferably 1.0 or greater and 1.3 or less.
Making the upper geometric standard deviation by number GSDv of the cellulosic particles according to this exemplary embodiment 1.0 or greater and 1.7 or less may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
If the GSDv is 1.0 or greater and 1.7 or less, it may be unlikely that residual fine particles (small particles, smaller than 3 µm) will affect texture because such fine particles are scarce; the changes in texture over time, therefore, may be smaller. In that case, furthermore, it may be unlikely that coarse particles (large particles, larger than 10 µm) will inhibit the biodegradation process (because the cellulosic particles break down at their surface first), and this may tend to help achieve superior biodegradability.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
The volume-average diameter and the upper geometric standard deviation GSDp of the cellulosic particles are measured as follows.
Particle diameters are measured using the LS particle size distribution analyzer “Beckman Coulter LS13 320 (Beckman Coulter),” and the cumulative distribution of particle diameters is plotted as a function of volume starting from the smallest diameter; then the particle diameter at which the cumulative percentage is 50% is determined as the volume-average particle diameter.
Separately, the cumulative distribution of particle diameters is plotted as a function of volume starting from the smallest diameter, and the particle diameters at which the cumulative percentage is 50% and 84% are defined as the number-average particle diameter, D50v, and particle diameter D84v by number, respectively. The upper geometric standard deviation by number GSDv is calculated according to the equation GSDv = (D84v/D50v)½.
The sphericity of the cellulosic particles according to this exemplary embodiment may be 0.90 or greater, preferably 0.95 or greater, more preferably 0.97 or greater.
Making the sphericity of the cellulosic particles according to this exemplary embodiment 0.90 or greater may make more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
If the sphericity is 0.9 or greater, the changes in texture over time may be smaller because the impact of surface defects, if any, may be minimized. In that case, furthermore, the particles may tend to be superior in biodegradability, too, because the distance from the surface to the inner core of the particles, for which microorganisms need to go to decompose the particles, may be the shortest.
For these reasons, presumably, it may be more certain that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
The sphericity is given by (circumference of the equivalent circle)/(circumference) [(circumference of a circle having the same projected area as the particle’s image)/(circumference of the particle’s projected image)]. Specifically, the sphericity is a value measured by the following method.
First, a portion of the cellulosic particles of interest is sampled by aspiration in such a manner that it will form a flat stream, and this flat stream is photographed with a flash to capture the figures of the particles in a still image; then the sphericity is determined by analyzing the particle images using a flow particle-image analyzer (Sysmex Corp. FPIA-3000). The number of particles sampled in the determination of the sphericity is 3500.
If the cellulosic particles have an external additive, the cellulosic particles of interest are dispersed in water containing a surfactant first; then the external additive is removed through sonication, and the sonicated particles are subjected to the measurement.
The surface smoothness of the cellulosic particles according to this exemplary embodiment may be 80% or higher, preferably 82% or higher and 99% or lower, more preferably 84% or higher and 98% or lower.
Making the surface smoothness of the cellulosic particles according to this exemplary embodiment 80% or higher may help ensure that the cellulosic particles are highly biodegradable and exhibit little change in texture over time. Possible reasons are as follows.
If the surface smoothness is 80% or higher, the changes in texture over time may be smaller because any instances of chipping of the surface of the particles may scarcely have impact on texture by virtue of the overall smoothness of the particles. In that case, furthermore, the cellulosic particles may tend to be superior in biodegradability because large-sized microorganisms (some kinds of biodegrading microorganisms are relatively large in size) can get access to the surface of the particles.
For these reasons, presumably, it may be likely that the cellulosic particles are highly biodegradable and exhibit little change in texture over time.
The surface smoothness is measured through a procedure as described below.
An SEM image (magnification, 5,000 times) of the cellulosic particles, taken with a scanning electron microscope (SEM), is observed, and the smoothness M of the individual cellulosic particles is calculated according to the equation below. The arithmetic mean smoothness M of any ten or more cellulosic particles is reported as the surface smoothness. The closer the smoothness M is to 1, the closer the surface of the cellulosic particles is to smoothness.
In this equation, S2 denotes the area of the cellulosic particle in the image (projected area), and S3 denotes, when the cellulosic particle in the image is superimposed on a circle having a projected area equal to S2, the sum of “the area outside the outline of the circle having a projected area equal to S2 and inside the outline of the cellulosic particle in the image” and “the area inside the outline of the circle having a projected area equal to S2 and outside the outline of the cellulosic particle in the image.”
The superposition of the cellulosic particle in the image on a circle having a projected area equal to S2 is done as follows.
The cellulosic particle in the image is superimposed on the circle having a projected area equal to S2 in such a manner as to maximize the area of overlap between the two images (the area inside the outline of the circle having a projected area equal to S2 and inside the outline of the cellulosic particle in the image).
A method for producing the cellulosic particles may include a step of producing a particle precursor containing a cellulose acylate (particle precursor production step) and a step of saponifying the cellulose acylate contained in the particle precursor (saponification step). Particle Precursor Production Step
A particle precursor containing a cellulose acylate is produced by any of methods (1) to (5) below.
In this context, a cellulose acylate is a cellulose derivative in which at least one of the hydroxy groups of cellulose has been replaced with an aliphatic acyl group (acylated). Specifically, a cellulose acylate is a cellulose derivative in which at least one of the hydroxy groups of cellulose has been replaced with -CO-RAC (RAC represents an aliphatic hydrocarbon group.).
Then the cellulose acylate contained in the particle precursor is saponified.
Through this step, the aliphatic acyl group(s) of the cellulose acylate is hydrolyzed, and the cellulose turns into cellulose.
The saponification step is performed by, for example, adding sodium hydroxide to a dispersion of the particle precursor and stirring the dispersion.
If coated cellulosic particles are produced, the production method may include a step of forming the coating layer (coating layer formation step) after the above saponification step.
If the coating layer formation step is performed, the coating layer is formed using the particles obtained through the above saponification step as core particles.
First, an aqueous dispersion in which the core particles are dispersed is prepared. The core particles may be cleaned with acid before the preparation of the aqueous dispersion.
Then the aqueous dispersion in which the core particles are dispersed is mixed with an aqueous solution containing the compound(s) that will form the first coating layer. This causes, for example, hydroxyl groups of the resin contained in the core particles to react with, for example, amine sites, carboxyl groups, or amino groups of the surface-treating polymer(s) or to form hydrogen bonds with hydroxyl groups of the polymer(s), and this produces the first coating layer. Then the aqueous dispersion in which the core particles with the first coating layer formed thereon are dispersed is mixed with an emulsion containing the compound(s) that will form the second coating layer. Through this, the second coating layer is formed.
Then the cellulosic particles having coating layers are removed from the mixture. The removal of the cellulosic particles having coating layers is done by, for example, filtering the mixture. The removed cellulosic particles having coating layers may be washed with water. This may help eliminate unreacted residue of the surface-treating polymer(s). Then the cellulosic particles having coating layers are dried, giving cellulosic particles according to this exemplary embodiment.
External additive(s) may be added to the resulting cellulosic particles.
An example of an addition step is a treatment in which the external additive(s) is added to the cellulosic particles using equipment like a mixing mill, V-blender, Henschel mixer, or Lödige mixer.
Applications of the cellulosic particles according to this exemplary embodiment include granular materials for use as cosmetics, a rolling agent, an abrasive, a scrubbing agent, display spacers, a material for bead molding, light-diffusing particles, a resin-strengthening agent, a refractive index control agent, a biodegradation accelerator, a fertilizer, water-absorbent particles, toner particles, and anti-blocking particles.
An application of the cellulosic particles according to this exemplary embodiment may be cosmetics.
An application of the cellulosic particles according to this exemplary embodiment may be a cosmetic additive in particular.
Potentially superior in flexibility, the cellulosic particles according to this exemplary embodiment, if used as a cosmetic additive, may help the cosmetic product to spread well on the skin to which it is applied.
The cellulosic particles according to this exemplary embodiment can be applied as cosmetic additives, for example to base makeup cosmetics (e.g., foundation primer, concealer, foundation, and face powder); makeup cosmetics (e.g., lipstick, lip gloss, lip liner, blush, eyeshadow, eyeliner, mascara, eyebrow powder, nail products, and nail care cosmetics); and skincare cosmetics (e.g., face wash, facial cleanser, toner, milky lotion, serum, face packs, face masks, and cosmetics for the care of the eye and mouth areas).
The resin particles according to this exemplary embodiment may be used as a cosmetic additive to makeup cosmetics in particular, because cosmetic additives to makeup cosmetics can need to be flexible and biodegradable.
Examples will now be described, but no aspect of the present disclosure is limited to these examples. In the following description, “parts” and “%” are all by mass unless stated otherwise.
The following materials are prepared.
The volume-average particle diameters of the external additives are measured through the same procedure as the volume-average diameters of the cellulosic particles.
One hundred thirty parts of cellulose acylate Cell is dissolved completely in 870 parts of ethyl acetate. The resulting solution is added to a water-based liquid containing 50 parts of calcium carbonate and 500 parts of purified water, and the resulting mixture is stirred for 3 hours (hereinafter referred to as “the first stirring time”). A dispersion of 4 parts of carboxymethyl cellulose (hereinafter also referred to as “CMC”) and 200 parts methyl ethyl ketone in 600 parts of purified water is added, and the resulting mixture is stirred for 5 minutes using a high-speed emulsifier. Ten parts of sodium hydroxide is added, and the resulting mixture is heated to 80° C. and stirred for 3 hours so that the ethyl acetate and the methyl ethyl ketone will be removed. The same amount of diluted hydrochloric acid as the sodium hydroxide is added, the residue is collected by filtration, and the collected solids are dispersed once again in purified water; this gives a particle precursor dispersion (solids concentration, 10%).
A mixture obtained by adding 17.5 parts of a 20% aqueous solution of sodium hydroxide to 500 parts of the particle precursor dispersion is stirred for 6 hours at a saponification temperature of 30° C. After the pH is adjusted to 7 with hydrochloric acid, the saponified slurry is cleaned by repeated filtration and washing until the electrical conductivity of the filtrate is 10 µs/cm or less; this gives cellulosic particles.
Cellulosic particles are obtained through the same procedure as in Example 1, except that in the particle precursor production step, the cellulose acylate species is as in Table 1.
Cellulosic particles are obtained through the same procedure as in Example 1. Coating Layer Formation Step
One thousand parts of the cellulosic particles, which are core particles, and 10000 parts of deionized water are mixed together; this gives a core particle dispersion. Five parts of Fir16, which will form the first coating layer, is added to the core particle dispersion, and the resulting mixture is stirred for 1 hour so that the compound will form a coating layer. The coated cellulosic particles are cleaned by repeated filtration and washing until the electrical conductivity of the filtrate is 10 µs/cm or less; this gives coated cellulosic particles.
Coated cellulosic particles are obtained through the same procedure as in Example 8, except that in the coating layer formation step, the species of the compound that will form the first coating layer (“First-layer compound” in Table 1) is as in Table 1.
Cellulosic particles are obtained through the same procedure as in Example 1. Coating Layer Formation Step
One thousand parts of the cellulosic particles, which are core particles, and 10000 parts of deionized water are mixed together; this gives a core particle dispersion. Five parts of Fir16, which will form the first coating layer, is added to the core particle dispersion, and the resulting mixture is stirred for 1 hour so that the compound will form a first coating layer; this gives a dispersion of cellulosic particles having a first coating layer.
Then an emulsion for the formation of the second coating layer is prepared by mixing 6 parts of wax Sec1 and 50 parts of purified water together using a high-speed emulsifier.
All of the emulsion for the formation of the second coating layer is added to the dispersion of cellulosic particles having a first coating layer, and the resulting mixture is stirred for 24 hours so that the wax will form the second coating layer; this gives a dispersion of cellulosic particles having first and second coating layers.
The cellulosic particles having first and second coating layers are cleaned by repeated filtration and washing until the electrical conductivity of the filtrate is 10 µs/cm or less; this gives cellulosic particles having first and second coating layers.
Cellulosic particles having first and second coating layers are obtained through the same procedure as in Example 26, except that in the coating layer formation step, the wax species is as in Table 1.
Cellulosic particles having first and second coating layers are obtained through the same procedure as in Example 26, except that in the coating layer formation step, the amount of the compound that will form the first coating layer and the amount of wax are as in Table 1.
Cellulosic particles having first and second coating layers are obtained through the same procedure as in Example 26.
A 0.6-part portion of external additive Sur1 is added to 30 parts of the cellulosic particles having first and second coating layers, and the ingredients are mixed together in a mixing mill (WONDER CRUSHER, Osaka Chemical); this gives cellulosic particles having an external additive.
Cellulosic particles having an external additive are obtained through the same procedure as in Example 44, except that in the addition step, the external additive and its amount are as in Table 1.
Cellulosic particles having an external additive are obtained through the same procedure as in Example 26, except that in the particle precursor production step, the amount of calcium carbonate, the first stirring time, the amount of carboxymethyl cellulose, and the amount of sodium hydroxide are as in Table 1.
Coated cellulosic particles are obtained through the same procedure as in Example 26 or 45, except that the coating layer formation step is done without the process of adding 5 parts of Fir16, the compound for the formation of the first coating layer, to the core particle dispersion and stirring the resulting mixture for 1 hour.
Cellulosic particles having an external additive are obtained through the same procedure as in Example 45, except that in the coating layer formation step, the wax species is as in Table 1 and that in preparing the emulsion for the formation of the second coating layer, the polyvalent metal salt specified in Table 1, its amount being as in Table 1, is added together with the wax and the purified water.
Cellulosic particles are obtained through the same procedure as in the above Examples, except that the parameters are changed to those indicated in Table 1.
The following particles are used as cellulosic particles of the comparative examples.
Comparative Example 1: CELLULOBEADS D10 (Daito Kasei, cellulosic particles containing cellulose as their base constituent. No coating layer and no external additive.)
Comparative Example 2: OTS-0.5A CELLULOBEADS D10 (Daito Kasei, cellulosic particles having a cellulose-based core particle and a coating layer containing triethoxyoctylsilane. No external additive.)
Comparative Example 3: S-STM CELLULOBEADS D-5 (Daito Kasei, cellulosic particles having a cellulose-based core particle and a coating layer containing magnesium stearate. No external additive.)
Comparative Example 4: CELLUFLOW C25 (JNC, cellulosic particles containing cellulose as their base constituent. No coating layer and no external additive.)
Cellulosic particles are obtained according to the procedure described in Example 1 in Japanese Patent No. 6872068. These cellulosic particles contain cellulose as their base constituent and have no external additive. The specific production process is as follows.
An oil phase is prepared by dissolving 250 parts by mass of diacetyl cellulose (CA398-3, Eastman Chemical) in 2500 parts by mass of ethyl acetate. A water phase is prepared by dissolving 200 parts by mass of polyvinyl alcohol in 2300 parts by mass of deionized water. The prepared water phase is mixed with the oil phase, and the resulting mixture is stirred at 1000 rpm for 3 minutes using a dissolver. The mixture is further stirred at 1800 rpm for 10 minutes using a dissolver to give a suspension in which the oil phase is dispersed uniformly.
While the resulting suspension is stirred at 500 rpm, 112500 parts by mass of deionized water is introduced over 75 minutes; this gives a dispersion of resin particles. The resin particles are collected by filtration, washed, and then stirred in deionized water. After filtration and washing, the resulting resin particles are dispersed in 2500 parts by mass of deionized water. Sodium hydroxide is added to make the pH 13.0 or below, the dispersion is heated to 60° C. for hydrolysis at the same time, and the dispersion is neutralized with hydrochloric acid. The product is collected by filtration, washed, and then immersed in deionized water. After filtration and washing, the solids are dried and crushed; this gives cellulosic particles.
Cellulosic particles are obtained according to the procedure described in Example 2 in Japanese Patent No. 6872068. These cellulosic particles contain cellulose as their base constituent and have no external additive. The specific production process is as follows.
An oil phase is prepared by dissolving 250 parts by mass of cellulose acetate propionate (CAP504-0.2, Eastman Chemical) in 1000 parts by mass of ethyl acetate. A water phase is prepared by dissolving 100 parts of polyvinyl alcohol in 1088 parts of deionized water and stirring the resulting solution with 62.5 parts of ethyl acetate. The prepared water phase is mixed with the oil phase, and the resulting mixture is stirred at 1000 rpm for 3 minutes using a dissolver. The mixture is further stirred at 1500 rpm for 5 minutes to give a suspension in which oil droplets are dispersed uniformly.
While the suspension is stirred at 500 rpm, 21250 parts by mass of deionized water is introduced over 60 minutes; this gives a dispersion of resin particles. The resin particles are collected by filtration, washed, immersed in deionized water, and stirred. After filtration and washing, the solids are dried and crushed into resin particles. The resulting resin particles are dispersed in 5000 parts by mass of deionized water. Sodium hydroxide is added to make the pH 13.0 or below, the dispersion is heated to 40° C. for hydrolysis, and then the dispersion is neutralized with acetic acid. The product is collected by filtration and washed; this gives cellulosic particles.
Cellulosic particles are obtained according to the procedure described in Example 1 in Japanese Unexamined Patent Application Publication No. 2021-021044. These cellulosic particles contain cellulose as their base constituent and have no coating layer and no external additive. The specific production process is as follows.
A 4.8-g portion of cyclohexanone is stirred with 0.2 g of diacetyl cellulose (L20, Daicel). The resulting mixture is further stirred at 60° C. for 3 hours to give a 4% by mass solution of diacetyl cellulose; this solution is the dispersed phase.
Fifty grams of purified water is stirred with 0.1 g of sodium dodecylbenzenesulfonate and 3.5 g of cyclohexanone. The resulting mixture is warmed to 60° C. to give an aqueous medium; this aqueous medium is the continuous phase. The dispersed phase, preheated to 60° C., and the continuous phase, also preheated to 60° C., are put into different inlets of a rotational cylinder emulsifier (cylinder outer diameter, 78 mm; cylinder length, 215 mm; cylinder inner diameter, 80 mm; clearance, 1 mm; Tipton) at 1 mL/min using a syringe pump (high-pressure microfeeder JP-H, Furue Science) and at 10 mL/min using a plunger pump (NP-KX-840, Nihon Seimitsu Kagaku), respectively, and emulsified at a cylinder rotational frequency of 2000 rpm for an emulsification period of 138 seconds to give an oil-in-water emulsion.
This oil-in-water emulsion is cooled to 5° C. and fed to a double-tube merger, and the diacetyl cellulose is precipitated by feeding purified water at 10 mL/min; this gives a solution of particle slurry.
The resulting diacetyl cellulose particles are put into a mixture of 7 parts by mass of a 55% by mass aqueous solution of methanol and 3.5 parts by mass of a 20% by mass aqueous solution of sodium hydroxide (concentrations based on the diacetyl cellulose particles), and the resulting mixture is stirred at 35° C. for 20 hours so that the diacetyl cellulose particles will be saponified; this gives cellulosic particles.
Cellulosic particles are obtained according to the procedure described in Example 1 in Japanese Unexamined Patent Application Publication No. 2021-021045. These cellulosic particles contain cellulose as their base constituent and have no coating layer and no external additive. The specific production process is as follows.
Diacetyl cellulose (L20, Daicel) is added to 64 g of ethyl acetate and 16 g of acetone, and the resulting mixture is stirred at 50° C. for 3 hours or longer to give a 10% by mass diacetyl cellulose solution.
This solution is poured into 82.8 g of purified water at 50° C. containing 0.18 g of sodium dodecylbenzenesulfonate and 6.2 g of ethyl acetate, and the resulting mixture is stirred at a rotational frequency of 300 rpm for 10 minutes; this gives a crude emulsion. A porous membrane (a cylindrical SPG membrane having an outer diameter of 10 mm, a thickness of 1 mm, and a pore diameter of 50 µm; SPG Technology) is immersed in a container holding 331.2 g of purified water at 50° C. containing 0.71 g of sodium dodecylbenzenesulfonate and 24.9 g of ethyl acetate, and the container in which the crude emulsion has been prepared is coupled to the inside of this porous membrane. The crude emulsion is forced through the membrane by applying a pressure of 100 kPa to the container in which the crude emulsion has been prepared; membrane emulsification induced by this gives an oil droplet-in-water emulsion.
This emulsion is cooled, and when its temperature is 20° C., 444 mL of purified water is added dropwise; this gives spherical diacetyl cellulose particles. Then the dispersion is centrifuged and filtered, and the residual diacetyl cellulose particles are washed thoroughly with plenty of water and collected by filtration; this yields 2.8 g of diacetyl cellulose particles.
The resulting diacetyl cellulose particles are put into a mixture of a 55% aqueous solution of methanol (7 parts by mass) and a 20% by mass aqueous solution of sodium hydroxide (3.5 parts by mass) (concentrations based on the diacetyl cellulose particles), and the resulting mixture is stirred at 35° C. for 20 hours so that the diacetyl cellulose will be saponified; this gives cellulosic particles.
CELLUFLOW TA25 (JNC, diacetyl cellulose particles. No coating layer and no external additive.) is used as cellulosic particles of Comparative Example 9.
Cellulosic particles are obtained according to the procedure described in Example 1 in Japanese Patent No. 6921293. The specific production process is as follows.
An oil phase is prepared by dissolving 150 parts of diacetyl cellulose (trade name “CA-398-6,” Eastman Chemical; acetyl content, 39.8%) in 1,350 parts of ethyl acetate (solubility in water, 8 g/100 g). A water phase is prepared by dissolving 100 parts of polyvinyl alcohol in 1,250 parts of deionized water. The prepared water phase is mixed with the oil phase, and the resulting mixture is stirred at 1,000 rpm for 3 minutes using a dissolver. The mixture is further stirred at 2,000 rpm for 10 minutes using a dissolver, giving a suspension in which oil droplets are dispersed uniformly. The volume-average diameter of the oil droplets measured by optical microscope observation and image analysis is 18 µm.
While the resulting suspension is stirred at 500 rpm using a dissolver, 42,000 parts of deionized water is introduced over 90 minutes; this gives a dispersion of resin particles. After filtration and washing, the resin particles are deflocculated in deionized water and stirred. The resin particles are collected by filtration, washed, and dispersed in 2,500 parts of deionized water. Sodium hydroxide is added to make the pH 13.0 or below, and the dispersion is heated to 50° C. for hydrolysis at the same time. After the end of the hydrolysis, the dispersion is neutralized with hydrochloric acid. The product is collected by filtration, washed, and then deflocculated in deionized water. After filtration and washing, the solids are dried and crushed; this gives core beads having a median diameter (D50) of 9 µm.
Fifty grams of the resulting core beads and 1.5 g of zinc stearate (trade name “SPZ-100F,” Sakai Chemical Industry; a powder of sheet-shaped particles; average particle diameter, 0.4 µm; thickness, 0.1 µm; aspect ratio, 3) are put into a small-sized mixer. The materials are dry-mixed for 3 minutes so that the surface of the core beads will be treated with the zinc stearate; this gives resin beads.
The resulting resin beads are used as cellulosic particles of Comparative Example 10. Comparative Example 11
Cellulosic particles are obtained according to the procedure described in Example 2 in Japanese Patent No. 6921293. The specific production process is as follows.
Resin beads are obtained in the same way as in Example 1 in Japanese Patent No. 6921293, except that the zinc stearate is replaced with 2.5 g of magnesium stearate (trade name “SPX-100F,” Sakai Chemical Industry; a powder of sheet-shaped particles; average particle diameter, 0.7 µm; thickness, 0.1 µm; aspect ratio, 4).
The resulting resin beads are used as cellulosic particles of Comparative Example 11. Examples 101 to 124
Coated cellulosic particles are obtained through the same procedure as in the above Examples, except that the parameters are changed to those indicated in Table 1.
The following characteristics of the cellulosic particles obtained in the Examples and Comparative Examples are measured according to the methods described previously herein.
For deterioration in smoothness over time, ten female testers spread the particles on the back of their hand and grade their feeling from 1 for “unsmooth” to 10 for “smooth”; the average rate of the ten testers is the score. This test is performed after the freshly produced particles are left at room temperature for 24 hours and in a temperature-controlled chamber at a temperature of 50° C. and a relative humidity of 85% rh for 96 hours (initial and follow-up tests, respectively), and the difference between the grades in the initial and follow-up tests is the deterioration in smoothness over time.
For deterioration in moist sensation over time, ten female testers spread the particles on the back of their hand and grade their feeling from 1 for “too dry” to 10 for “moist”; the average rate of the ten testers is the score. This test is performed after the freshly produced particles are left at room temperature for 24 hours and in a temperature-controlled chamber at a temperature of 50° C. and a relative humidity of 85% rh for 96 hours (initial and follow-up tests, respectively), and the difference between the grades in the initial and follow-up tests is the deterioration in moist sensation over time.
For deterioration in softness over time, ten female testers spread the particles on the back of their hand and grade their feeling from 1 for “hard and difficult to spread” to 10 for “very soft”; the average rate of the ten testers is the score. This test is performed after the freshly produced particles are left at room temperature for 24 hours and in a temperature-controlled chamber at a temperature of 50° C. and a relative humidity of 85% rh for 96 hours (initial and follow-up tests, respectively), and the difference between the grades in the initial and follow-up tests is the deterioration in smoothness over time.
These results indicate that the cellulosic particles of the examples may be highly biodegradable and exhibit little change in texture over time compared with those of the comparative examples.
A variety of cosmetics are produced using the cellulosic particles of Examples and Comparative Examples indicated in Table 4. The specific processes are as follows.
Liquid foundation is obtained by a known method according to the formula presented in Table 3-1.
A milky lotion is obtained by a known method according to the formula presented in Table 3-2.
A loose powder is obtained by mixing the ingredients listed in Table 3-3 in a blender, milling the mixture in a mill, and sieving the particles through a 250-µm mesh sieve.
Powder foundation is obtained by mixing the particles and powders according to the formula presented in Table 3-4, mixing binders according to the same, gradually adding the mixture of particles and powders into the binders with stirring, and then mixing the mixture.
According to the formula presented in Table 3-5, oil phase (1) is warmed to 50° C. until dissolution, and the solution is mixed with oil phase (2). Water phase (2) is brought into dissolution, and the solution is mixed. The particles and the powders are added to the mixture of oil phases (1) and (2) and dispersed and mixed, and then the mixture of water phases (1) and (2) is added gradually for emulsification; this gives a sunscreen cream.
According to the formula presented in Table 3-6, water phases (1) and (2) are mixed together. Then oil phase (1) is mixed and added to the mixture of water phases (1) and (2). Oil phase (2) is warmed to 70° C., and the particles are added to it; this gives a dispersion. The resulting dispersion is added to the mixture of water phases (1) and (2) and oil phase (1), and the resulting mixture is stirred and mixed for emulsification. Stirring the emulsion with the neutralizing agent and cooling the mixture gives an all-in-one gel.
According to the formula presented in Table 3-7, the particles are dispersed in component A, and the resulting mixture is stirred. Adding component B and stirring the resulting mixture gives a foundation primer.
According to the formula presented in Table 3-8, component B is heated to 60° C. and mixed. The particles are dispersed in the mixture, the resulting dispersion is microwaved with component A until dissolution, and the solution is mixed and then cooled in a mold. Enclosing the resulting solid into a lipstick case gives a lip primer.
A body powder is obtained by mixing the ingredients listed in Table 3-9 together.
According to the formula presented in Table 3-10, the particles and powders are mixed together, and the mixed powder is further mixed with a homogeneous solution of the binder; shaping the mixture by compression molding gives a solid powder eyeshadow.
The resulting cosmetics are subjected to the above-described texture evaluations (smoothness, moist sensation, and softness) after 24 hours of storage in a temperature-controlled chamber at a low temperature (0° C.) and after 24 hours of storage in a temperature-controlled chamber at a high temperature (60° C.).
These results indicate that cosmetics made with cellulosic particles of examples, compared with those of comparative examples, may produce superior skin feelings (smoothness, moist sensation, and softness) even at high or low temperatures.
The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.
(((1))) A cellulosic particle containing:
(()) The cellulosic particle according to (((1))), containing:
(()) The cellulosic particle according to (((2))), wherein the polyamine compound is at least one selected from the group consisting of polyethyleneimine and polylysine.
(()) The cellulosic particle according to (((2))) or (((3))), wherein the wax is carnauba wax.
(()) The cellulosic particle according to any one of (((2))) to (((4))), wherein the coating layer has a first coating layer covering the core particle and containing at least one selected from the group consisting of the polyamine compound, the arginine compound, the linear-chain fatty acid, the hydroxy fatty acid, and the amino acid compound and a second coating layer covering the first coating layer and containing at least one selected from the group consisting of the wax, the linear-chain fatty acid, the linear-chain fatty acid metallic salt, the hydroxy fatty acid, and the amino acid compound.
(()) The cellulosic particle according to (((5))), wherein the second coating layer further contains a polyvalent metal salt.
(()) The cellulosic particle according to any one of (((2))) to (((4))), wherein the coating layer has a first coating layer covering the core particle and containing at least one selected from the group consisting of the polyamine compound and the arginine compound and a second coating layer covering the first coating layer and containing at least one selected from the group consisting of the linear-chain fatty acid, the linear-chain fatty acid metallic salt, and the amino acid compound.
(()) The cellulosic particle according to (((7))), wherein the second coating layer further contains a polyvalent metal salt.
(()) The cellulosic particle according to any one of (((1))) to (((8))), further having at least one external additive selected from the group consisting of a silicon-containing compound particle and a metallic soap particle.
(()) The cellulosic particle according to (((9))), wherein the silicon-containing compound particle is a silica particle.
(()) The cellulosic particle according to any one of (((1))) to (((10))), wherein the volume-average diameter of the cellulosic particles is 3 µm or more and less than 10 µm.
(()) The cellulosic particle according to any one of (((1))) to (((11))), wherein the upper geometric standard deviation by number GSDv of the cellulosic particles is 1.0 or greater and 1.7 or less.
(()) The cellulosic particle according to any one of (((1))) to (((10))), wherein the sphericity of the cellulosic particle is 0.9 or greater.
(()) The cellulosic particle according to any one of (((1))) to (((13))), wherein the number-average molecular weight of the cellulose is 37000 or more.
(()) The cellulosic particle according to (((14))), wherein the number-average molecular weight of the cellulose is 45000 or more.
(()) The cellulosic particle according to any one of (((1))) to (((15))), wherein the surface smoothness of the cellulosic particle is 80% or higher.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-017985 | Feb 2022 | JP | national |
| 2022-122215 | Jul 2022 | JP | national |
