Patent Application
20220202624
The present invention relates to the use of microparticles in a self-adhesive silicone gel to increase adhesion. It concerns a self-adhering silicone gel comprising microparticles and having improved adhesion properties, in particular when it also comprises additional chemical compounds/derivatives, and more particularly active compounds, soluble or miscible in the silicone gel.
Cosmetic or pharmaceutical compositions, in particular transdermal compositions, comprising an adhesive layer and particles are known, in particular from applications WO 2013/127929 or FR 2 781 667. These compositions may include an adhesive matrix based on silicones, which are not gels, and mineral or organic particles. However, the addition of particles to these adhesive matrices leads to a decrease in its adhesion properties to the skin, or ‘tack’. This reduction in adhesion limits the possible uses of these compositions.
The use of self-adhesive silicone gels in the medical field, for example for the production of active dressings or topical treatments is known in particular from FR 2 735 024, FR 2 879 931, WO2005/051442, WO2008/057155 and WO2017/158249. However, the introduction of liquids into adhesive silicone gels leads to a degradation of their consistency and adhesion. In addition, the degradation of their consistency and adhesion can also result from the addition of particles. US2016263270 describes adhesive silicone gels which contain powders of antibacterial agents whose content must be limited to 5% in order not to degrade the performance of the gel.
Polyaddition self-adhesive silicone gels have various applications, particularly in the medical and cosmetic fields, where they can be used as dressings or patches to be applied to the skin. These gels are well known to the profession and are the product of the hydrosilylation of two functionalized organosiloxane components in the presence of a catalyst. They are described in patents and patent applications U.S. Pat. No. 4,072,635, EP 69 451, EP 322 118, EP 737 721, FR 2 856 072, FR 2 879 931 and EP 3 356 490.
Furthermore, in certain applications silicone gel is used as a self-adhesive matrix containing an active substance, either liquid or solid, which may be in pure form or in solution in a solvent and at least part of which pure form or solution is soluble in or miscible with silicone gel. This makes it possible to impart therapeutic and/or physicochemical properties to an object made with the said gel. However, the solubilisation of a substance in a silicone gel or the incorporation of a miscible liquid into a silicone gel has the effect of greatly reducing the adhesion and consistency of the latter.
It is therefore interesting to find a solution that makes it possible to preserve or even increase the adhesion of adhesive matrices in particular for skin applications in cosmetics or for therapeutic applications, especially when the gels contain dissolved or miscible added substances.
A purpose of the invention is to make it possible to increase the adhesion of a self-adhesive silicone gel, whether or not it contains a substance at least part of which is soluble or miscible in silicone gels; the substance may be a solid, a pure or complex liquid or a solution.
The present invention relates to a self-adhesive composite silicone gel (SACSG), comprising microparticles (μP) in a self-adhesive silicone gel (SASG), characterized in that it comprises by weight relative to the total weight of the SACSG at least 0.5%, in particular at least 10% of microparticles whose adsorption capacities are greater than or equal to 0.5 ml/g.
The invention relates more particularly to a SACSG which comprises at least 0.5% by weight relative to the total weight of the SACSG of porous microparticles whose adsorption capacities are greater than 1 ml/g.
The invention also concerns a pharmaceutical or cosmetic composition, characterized in that it comprises such a SACSG according to one of the claims.
It also concerns an adhesive film for cutaneous application comprising a layer (back layer), a layer adhering to the skin and a protective layer that can be removed, characterized in that the layer adhering to the skin is a SACSG according to the invention.
The invention also relates to the SACSG for its use in therapy.
It also relates to the use of particles, in particular porous particles, to increase the adhesion of self-adhering composite silicone gels, particularly on the skin.
Gels are highly deformable materials that consist of three-dimensional networks of polymers. These networks are formed by the association of polymer chains via permanent or reversible connections. There are two types of gel: chemical gels and physical gels.
Chemical gels are made up of polymer chains linked together by covalent bonds. They therefore have a high stability and the structuring of the gel is said to be irreversible.
On the contrary, physical gels are reversible. The connections are low-energy bonds, and thus depend on the thermodynamic and mechanical states of the gel.
An example of a physical gel is described in patent application WO00/73374.
In the remainder of this text, the term:
They are conventionally constituted by the product of a hydrosilylation reaction occurring in a mixture of constituents essentially comprising:
The proportions between the alkenyl groups and the hydrogeno silane groups and the proportions between the Si—H of polydimethylsiloxanes I and II are a means of controlling the consistency and the adhesion of the gels. It is also possible to control the characteristics of formulations and gels resulting from cross-linking reactions by introducing into these formulations particular constituents such as silicone resins and by adjusting the ratios between the different constituents present in the mixtures.
They are described in particular in US patents and patent applications U.S. Pat. No. 4,072,635, EP 69 451, EP 322 118, EP 737 721, FR 2 856 072, FR 2 879 931 or EP3356490 (A1).
Preferably, the SASG according to the invention are defined in the patent application FR 2 879 931, the contents of which are incorporated here by reference. These SASG are also commercially available, in particular under the references Silpuran 2110, 2112, 2114, 2120, 2130 from Wacker, Silbione RT Gel 4317, 4642, 4717, HC2 2022, HC2 2031 from Elkem and Dow Corning MG7-9800, MG7-9850, MG7-9900 from Dow Corning, or marketed by Shinetsu or Nusil.
Silicone gels are generally characterized by a penetration value, or consistency, ranging from 90 to 350 tenths of a millimetre according to DIN ISO 2137. They are generally in the form of two-component systems which consist of a Part A and a Part B; the mixing in equidistant quantities of these two parts initiates the cross-linking reaction which leads to the formation of the silicone gel.
The viscosity and consistency characteristics of commercial silicone gels are given in Table 1 below (consistency is measured according to DIN-ISO 2137 and a cone of 62.5 g).
(m/density of the liquid or solid)/(n×CAP)
The density is expressed in g/ml at 25° C.
(volume(in ml) of the active derivatives[solids-liquids-solutions]present in 100 g of SACSG)/(QμPp×CAP).
The person skilled in the art will determine the content of microparticles in the SACSG according to the invention on the basis of the chemical nature of the particles, their granulometry, their adsorption capacity, the desired adhesion properties and the presence or absence of a substance or product at least partially soluble or partially miscible with silicone gel, in particular an active agent.
The microparticles and in particular the porous microparticles which may be used according to the invention are well known to the person skilled in the art; they may be of organic, mineral or organo-mineral origin, they may be hydrophobic or hydrophilic.
Among the hydrophobic porous particles, one can mention in particular the particles of organic origin obtained from:
Particles which are hydrophilic or at least comprise surface hydroxyl groups, which comprise the hydroxyl groups present on the surface of the particles and the hydroxyl groups present on the surface of the pores, may also be used according to the invention, provided however that their possible interactions with the catalyst or another constituent of silicone gels such as polyorganosiloxanes carrying hydrogen siloxy units are taken into consideration; these reactions may furthermore be catalysed by the acidic or basic character of the particles. The selection of hydrophilic particles should therefore be carried out according to their hydroxyl group content and their acid-base character. It is also possible to use microparticles that have been “passivated”, i.e. for which the presence of hydroxyl groups has been masked beforehand and/or their surface hydroxyl content has been modified. The masking of the surface hydroxyl groups can simply be carried out when the particles are impregnated or by a substance which may preferably be poorly soluble or insoluble or still immiscible or partially miscible in silicone gels. Alternatively, particles may be used whose surface hydroxyl groups have previously been functionalized, e.g. by silylation. Such passivation methods are well known to person skilled in the art. In particular, for silica particles, a water-repellent treatment can be carried out, for example by substituting the hydrogen atoms of the groups ≡Si—OH with trimethyl silyl [—Si(CH3)3] groups using hexadimethylsilazane, for example. Evonik's “Aeroerl R806”, Dow Corning's “Dow Corning VM 2270”, Sunjin Beauty Science's “Sunsil 130H SC”, “Sunsil 150H SC”, Evonik's “Aerosil RX 50”, “Aerosil RX 200” are examples of treated silica particles that are commercially available. Aerosil RY 50” and “Aerosil RY 200” are examples of silica particles passivated by adsorption of silicone oils that are marketed by Evonik.
SACSG may also contain so-called dense microparticles, particles with an adsorption capacity of less than 0.75 ml/g, which may be silicone elastomer particles such as Shin Etsu's “KSP 101” and “KSP 300” or “Dow Corning 9506” and “Dow Corning 9701”; polyethylene particles such as Sumitomo's “Flo-Bead 2080” or “3040”. These dense particles can also be active particles such as Impag's “Microsilver BG” or silver salt impregnated zeolites such as Sciessent's “Agion Antimicrobial type AJ”.
The content of microparticles in the SACSG according to the invention will depend in particular on their adsorption capacity. The person skilled in the art will be able to determine the quantities of particles according to his objective of adhesion (“tack”) and/or rigidity. It has been determined that the effects of the microparticles increase as a function of the CAT. Thus, for an improvement of about 20% in adhesion and shear modulus, a CAT of 3 to 8 ml/100 g of SACSG is required.
In general, the SACSG according to the invention may comprise up to 50% of microparticles, in particular from 0.5 to 40% by weight, preferably from 0.5 to 25%. According to a particular embodiment, the SACSG comprises from 0.5 to 15% of microparticles. According to another particular embodiment, it comprises from 0.5% to 8% microparticles.
For so-called dense microparticles whose adsorption capacity is less than 0.75 ml/g, the SACSG will advantageously comprise at least 6% microparticles. For porous microparticles with an adsorption capacity of at least 0.75 ml/g, the SACSG will advantageously contain at least 0.5% porous microparticles, or even at least 10%, or even at least 2% porous microparticles, and advantageously up to 8% or even 15% or more.
When using porous microparticles, advantageously porous microparticles with an adsorption capacity (CAP) of more than 1 ml/g to more than 15 ml/g should be used. The content of these microparticles in the SACSG according to the invention will generally be from 0.5 to 30%, advantageously from 0.5 to 15%.
Porous microparticles with a CAP of at least 0.75 ml/g and up to 1.25 ml/g include “Orgasol 2002 U D Nat Cos” and “Orgasol 2002 D Nat Cos”.
According to a particular embodiment, porous microparticles have a PAC of 1.25 to 3 ml/g. In particular, mention may be made of “Celite 266”, “Kieselgel 60” HMDZ-treated, Aerosil RY 200, “Aeroperl R806” silylated silica, “Sunsphere H 122” and “Sunsphere H 122” HMDZ-treated, “Aeroperl 300-30” and “Aeroperl 300-30” HMDZ-treated, “Sun PMMA-P” and “Sun PMMA PH”.
According to another embodiment, the porous microparticles have a PAC of at least 3 ml/g. In particular, mention may be made of “Polypore E100”, “Sipernat 50” and “Sipernat 50” treated with HMDZ, “Sun PMMA-X”, “Polytrap 603” and “Dow Corning VM 2270”.
In general, porous microparticles have an average particle size of 0.1 μm to 600 μm, preferably less than 500 μm, more preferably less than 100 μm. The skilled person in the art will determine the appropriate particle size according to the thickness of the materials to be prepared from the SACSG and the viscosity of the non-crosslinked SACSG; in order to limit the increase in viscosity of non-crosslinked SACSG, it is preferable to use μP with larger particle sizes. Advantageously, microparticles have an average particle size of at least 0.1 μm, in particular from 0.1 μm to 300 μm, more particularly from 1 μm to 100 μm, advantageously from 5 μm to 50 μm.
According to a preferred embodiment, porous microparticles have an average particle size of between 5 μm and 50 μm.
According to an embodiment, mixtures of microparticles with different average particle sizes and/or different CAP may be used.
Table 2 in
One way for the skilled person to determine the quantity of particles used in the SACSG according to the invention is to calculate the Total Adsorption Capacity (TAC) of all the particles used per 100 g of SASG.
Advantageously, the SACSG according to the invention has a CAT greater than or equal to 3 ml per 100 g of SACSG. According to a particular embodiment, the SACSG has a CAT of at least 5 ml/100 mg, which may be as high as 30 ml/100 mg, or even higher.
The invention also relates to a SACSG as previously defined which also includes one or more additional chemical compounds/derivatives, and more particularly active compounds, soluble or miscible in silicone gel. These chemical compounds, in particular active agents, can be advantageously adsorbed in the pores of the microparticles. They can be liquid at room temperature, miscible or partially miscible with SASG or with one of its constituents. When the liquid chemical compound is little or not miscible with the cross-linked or non-cross-linked SACSG, it can be solubilized in a solvent miscible with the cross-linked or non-cross-linked SACSG to form a solution which will be at least partially miscible with the cross-linked or non-cross-linked SACSG. They may also be solid and at least partially soluble in the cross-linked or non-cross-linked SASG. When the solid additional chemical compounds/derivatives are sparingly or not at all soluble in the cross-linked or non-cross-linked SASG they may be dissolved in a solvent miscible with the cross-linked or non-cross-linked SASG; this solution shall form a liquid at least partially miscible with the cross-linked or non-cross-linked SASG.
These chemical compounds, in particular these active agents may be used in cosmetics or therapy, depending on the biological or therapeutic effects sought.
The active agents used in cosmetics are well known to the skilled person, notably marketed in the products of companies specialising in the manufacture and marketing of cosmetic products such as L'OREAL, PROCTER & GAMBLE, UNILEVER, SHISHEIDO, CLARINS, CAUDALIE, tec.
Cosmetic active agents may be chosen for their antiseptic, antibiotic, emollient, moisturizing, photo-protective, astringent, exfoliating, skin and cell renewal stimulating, slimming, skin absorption promoting activity.
They can be of natural or synthetic origin.
They can be in the form of plant powder or nebulisates of plant extracts, concrete oils, oleoresins, essential oils, oily extracts, liposoluble molecules. These ingredients must be compatible with the SACSG according to the invention, and will be chosen in particular among the following derivatives:
The active agents used for their therapeutic activities are well known to the skilled person, especially those used by cutaneous or transdermal administration. Examples of active agents according to the invention include antibacterial agents, antiseptics, antivirals, keratolytics, antioedematous agents, antinaupathic agents, protein and thyrosine inhibitors, kinase, anticholinergics, monoclonal antibodies, withdrawal agents, anti-anxiety agents, local anesthetics, analgesics, antimycotic agents, antiacne agents, sedatives and tranquilizers, anxiolytics, hormones, androgenic steroids, estrogenic steroids, progestin steroids, analgesics, hypoglycemics, antispasmodics, beta-blockers, non-steroidal anti-inflammatory drugs, steroidal anti-inflammatory drugs, anti-osteoporotic agents, skin whitening agents, vasodilators, antihypertensives, antiparkinsonian drugs, migraine drugs, antineoplastics, vitamins, essential amino acids, essential fatty acids.
They may be in powder or liquid form, or in adsorbed, absorbed or encapsulated form. These ingredients will preferably be compatible with the SACSG according to the invention, and in particular:
It is understood that the active ingredients identified for each category above are identified as representative examples of the class of activity, but are in no way intended to limit the list. The person skilled in the art shall know, as necessary, how to identify and use other active ingredients of a given category to implement the invention.
The active agents may be used alone or in mixtures.
The SACSG according to the invention may include:
The amount of additional chemical compounds/derivatives will be determined according to the use of the prepared SACSG, and the nature of the additional compound in combination with the microparticles to be selected.
It has been observed that the addition of these soluble or miscible compounds will decrease the adhesion and stiffness properties of the SACSG. The person skilled in the art will therefore be able to determine the quantities of microparticles and soluble or miscible compounds according to his objective, both in terms of the content of additional compounds and the adhesion and rigidity properties sought according to the use that will be made of the SACSG.
Thus, the SACSG according to the invention makes it possible to obtain silicone gels which comprise from 5% to 40% by weight of liquid compounds or in solutions which have adhesion and rigidity properties at least equal to those of the corresponding pure silicone gel, i.e. without microparticles and without additional compounds.
According to a particular embodiment the SACSG may contain up to 10% to 25% by weight of additional chemical compounds/derivatives, in particular active agents, relative to the total weight of SACSG, from 15 to 20% by weight.
These percentages apply both to the additional compounds alone or to the solutions containing them. For an additional compound alone, in particular active agent alone or a mixture of active agents alone, the percentage applies to the compound alone or to the mixture of compounds. If the additional compound must be solubilized in a compatible solvent to be miscible with SACSG, then the percentage applies to the solution containing the additional compound(s), in particular the active agent(s).
These additional chemical compounds, in particular of active agents alone, in mixtures or in solution, may be introduced directly into one of the constituents of the SASG or by the introduction of microparticles which will have been previously impregnated with these active agents or solutions of active agents. When the active agents are poorly/not very soluble or poorly/not miscible in/with the SASG, they should preferably be introduced in the form of solutions in a solvent so as to be able to form a liquid which will be at least partially miscible with the SASG.
Solvents which are miscible with the constituents of the SACSG according to the invention and more particularly usual solvents suitable for cosmetic or pharmaceutical use, shall be used as solvents. These solvents may, if necessary, themselves be active ingredients due to their properties. Particular mention should be made of organic solvents such as isopropyl myristate, isopropyl palmitate, isotridecyl isononylnonanoate, neopentyl glycol dioctanoate, branched parafins such as isododecane; cyclic silicone derivatives which consist of 4, 5, 6, 7 siloxyl units; phenyl derivatives of silicones such as diphenylsiloxy phenyl trimethycone; organofunctional silicones. One can also mention, for example, comb copolymer type copolyols which comprise a polydimethylsiloxane chain on which are grafted polyether chains or KF-6038 which consists of a polydimethyl siloxane chain to which polyether chains and alkyl chains are grafted and is marketed by Shinetsu. Liquid actives which are at least partially miscible or miscible with cross-linked or non-cross-linked SASG can also be used as solvents.
The SACSG according to the invention may also contain, together with the additional chemical compounds, liquid, mixed or in solution, other additional compounds such as dense microparticles of solid actives, microcapsules, etc.
In this case, the SACSG according to the invention will advantageously comprise from 5 to 40% of additional compound(s).
According to a particular mode, the SACSG will comprise at least 50% of silicone gel, at least 5% of an additional chemical compound, at least 10% of microparticles whose adsorption capacity is greater than or equal to 1 ml/g, in particular from 1 to 15%, and from 5 to 30% of additional compound(s).
The person skilled in the art will be able to determine the total quantity of liquid (solution, liquid additional compound or mixture of liquid additional compounds) in the SACSG according to the invention as a function of the desired adhesion properties, but also due to the microparticles and the chemical compatibility, miscibility, of the liquid with the silicone gels.
In particular, it is possible to identify a maximum ratio between the contents of liquid or solid active derivatives and the contents of μP identified by a Total Impregnation Rate (TIR) determined according to the following formula:
[amounts (in ml) of liquids or solids]/[amounts of μP(in g)×μP adsorption capacities(in ml/g)].
The quantities correspond to those present in 100 g of SACSG.
When SACSG do not contain dense microparticles of solid active ingredients, the TIT value must be advantageously lower than a value between 0.45 and 1.2.
When the SACSG according to the invention are used to manufacture films or patches, they advantageously have a thickness of 0.015 mm to 5 mm, preferably 0.015 to 3 mm. This thickness may be of several cm when SACSG are used to manufacture moulded parts.
SACSG according to the invention can be prepared by one of the following methods:
When the substance to be introduced into the mixture [(A+B)+microparticles] is a solid, preferably direct mode 2 or indirect mode 2 is used; these modes can also be advantageously used to prepare SACSG from liquid-impregnated microparticles.
These impregnated particles are used as in the case of direct mode 1. Parts A and B are first mixed, then the desired quantity of impregnated microparticles is added to the mixture (A+B); the mixture (A+B)+impregnated microparticles is homogenized, the desired quantity of any additional liquid phase is added to the mixture [(A+B)+impregnated microparticles], the mixture [(A+B)+impregnated microparticles]+possibly liquid phase is homogenized and then degassed at 20-50 mbar for 10 minutes; the degassed mixture is used to obtain the desired adherent material.
These modes of preparation are given for information only. The person skilled in the art will be able to adapt them according to particular constraints, in particular the presence or absence of volatile derivatives, the distribution of impregnated or non-impregnated μP, active agents, liquids or solvents in a heterogeneous manner in parts A and B, etc.
The mixtures [A+B+microparticles], [A+B+microparticles+active and/or liquid agents] as well as the mixtures [A′+B′] can be implemented by casting, injection and/or coating techniques in order to be able to lead, after cross-linking, to materials which can be handled: films, coated fabrics, moulded parts, etc. In the context of the targeted applications, formulations are preferred where the viscosities of the mixtures [A+B+microparticles+active and/or liquid agents] or the mixtures [A′+B] are between 1000 and 500,000 mPa·s or at least correspond to a self-levelling mixture at a temperature of between 15° C. and 120° C. In the case where the mixtures are used according to a coating technique on a support, compositions with a viscosity between 25 000 mPa·s and 50 000 mPa·s are preferred.
This viscosity will depend on the combination of parts A and B, the CAT and the content of active and/or liquid agents.
In the case where the formulation contains liquid ingredients of volatile character, the cross-linking reaction must be able to be carried out under conditions of temperature and time compatible with the thermal stability and volatility of the liquid ingredients; silicone formulations are preferred whose cross-linking can be carried out at temperatures below 120° C. and preferably between 40° C. and 80° C.; the reactivity of the mixtures can be adjusted by varying the platinum catalyst contents.
The SACSG according to the invention can be used in multiple fields due to their advantageous properties, both in cosmetics and in therapy or in any industry which has a use for such SACSG. Particular mention should be made of the therapeutic uses, particularly transdermal, in cosmetics, for protective parts for orthoses and prostheses, for damping, electrical insulation, assembly, etc.
The SACSG according to the invention can be prepared in various forms according to their applications, occlusive strips, liquid-permeable strips, films, moulded parts, composite parts (reinforced SACSG parts), etc.
The invention also relates to an adhesive or patch dressing for skin application comprising an outer layer (back layer) which is arranged on the side of the SACSG opposite to that which will be applied to the skin, a layer adhering to the skin, characterized in that the layer adhering to the skin is a SACSG according to the invention as defined above.
For the storage of the dressing, it also comprises a peelable protective layer on the side of the SACSG intended to be applied to the skin.
The outer layers are made of the materials customary in the field. They are chosen according to their mechanical properties, their compatibility with silicone gels, their permeability to water vapour and their ability to act as a barrier to UV rays; they must also be impermeable to active ingredients. These materials may be selected from thermoplastic polymers such as high or low density polyethylenes, polypropylenes, copolymers of ethylene and vinyl acetate, polyethylene terephthalates, or complexes of these materials with aluminium foil. The carrier may also be an elastic material such as polyurethanes or silicone elastomers. Such elastic supports may also be made of composite materials formed by combinations of an elastic fabric and a polyurethane sheet as described in EN 2904214 or application EP0976383.
SACSG according to the invention can also be used to make liquid-permeable dressings such as those described in U.S. Pat. No. 4,921,704.
SACSG according to the invention may also be used for the manufacture of moulded parts, composite parts (reinforced gels) or coated textiles, in particular for the manufacture of prostheses, orthoses, etc. which are also part of the present invention.
1. Preparation of Materials for Performance Characterization.
In addition, when the formulations contain volatile constituents, the dishes are sealed by applying a Teflon tape; then after the first phase of cross-linking at room temperature on the horizontal plate, the dishes are introduced into a container which can be closed tightly before being treated at 70° for 48 hours. This procedure minimises losses during the two phases of cross-linking; the contents of volatile derivatives can be checked by subjecting the films to drying at 700 in an oven.
2. Characterization of Gel Adhesion
Since patches are one of the main applications for which these self-adhering silicone layers are intended and since in this type of application the patches are applied to the skin without exerting strong pressure, the Tack measurement was preferred as a means of characterizing adhesion. Tack is classically characterized according to the so-called “Probe Tack” test described in ASTM D 2979. It consists of applying to the surface of the silicone gel film a cylindrical rod 5.2 mm in diameter and then measuring the peel force when the rod is vertically torn from the surface of the gel film. The rod is applied to the surface of the gel film until a force of 2N is reached (application speed 10 mm/min), after holding the rod for 1 s, the rod is vertically torn off from the surface at a speed of 250 mm/min. The Tack corresponds to the maximum value of the tear-off force that is recorded. This test procedure was developed for the characterization of thin films of adhesives with thicknesses well below 100 μm. In the case of thicker layers (thickness from 500 μm to more than 2 mm) this method is no longer applicable.
The measurement of tack is therefore carried out using the Probe Tack method, whose test procedure is derived from that described above in the case of ASTM 2979.
The device used is the Rheometer RS-6000 marketed by the Thermofischer company equipped with a 10 mm diameter rod. The roughness of the rod end meets the criteria of the ASTM 2979 standard.
The samples are discs of 2 mm thickness and 54 mm or 50 mm diameter which are respectively prepared extemporaneously in polystyrene Petri dishes of 56 mm diameter or in glass Petri dishes of 53 mm diameter according to the method described above. The 2 mm thick samples contained in the Petri dishes are attached to the Rheometer stage.
Test Procedure:
Zero determination: An empty Petri dish is attached to the rheometer plate. The 10 mm diameter rod is lowered vertically at a speed of 50 mm/min. until contact is made with the bottom surface of the Petri dish (detection by the instrument of a force other than zero); the position of the rod is recorded by the instrument and corresponds to the 0 dimension of the rod.
Tack measurement: the Petri dish is replaced by a box containing the 2 mm thick disc whose Tack must be determined. The 10 mm bar is lowered vertically at a speed of 3 mm/min until a force of 0.2N is applied to the surface of the sample. This force of 0.2N is maintained for a period of 30 seconds and then the rod is pulled vertically out at a speed of 150 mm/min.
The Tack is expressed by the maximum value of the tear-off force and is expressed in g/cm2.
Three measurements are made on three different samples, and under these conditions standard deviations of less than or equal to 10 are obtained.
3. Measurement of Gel Consistency
The consistency of the gels is characterized by their elastic shear modulus, which is measured as follows:
This type of measurement makes it possible to characterize the value of the elastic component of the shear modulus G′, as well as the gel time which corresponds to the time which elapses between the moment when the temperature of the sample reaches the value of 70° C. and the moment when the value of G′ becomes higher than that of G″ (G″ corresponds to the loss component of the shear modulus). When the gels develop high damping capacities which result in a value of the ratio G″/G′ equal to 1 after total cross-linking, the value of G′ at 4000 s is assimilated to that of G″ at 4000 s. These values are expressed in Pa.
4. Measurement of the Adsorption Capacity
Adsorption capacities are measured according to the method described in ISO 787-5. This method consists of gradually adding linseed oil to 2-1 g of powder until a cohesive paste is obtained. A value of Adsorption Capacity is obtained which is expressed in ml linseed oil/g μP.
The following examples describe the effects of the addition of 2.4% to 9.9% μP in SACSG compositions, which are described in Table 4 in
Table 3 in
Table 4 in
The following examples describe the influence of adding different amounts of particles to the following two SASG: RT Gel 4317 and RT Gel 4642. The ASG were prepared using direct mode 1; Tables 5 and 6 in
All these results show that the effects of the microparticles increase systematically with their contents and adsorption capacities. From the data concerning the compositions, it is possible to calculate the Total Adsorption Capacity (TAC) which is equal to the content of microparticles in the SACSG multiplied by their Adsorption Capacities. These results also show that globally the values of Tack and G′ increase with the values of the CAT.
The following examples describe the degradation of SASG performance by the introduction of miscible or partially miscible liquids or solubilization of a solid. In these tests Isopropyl Myristate, Methyl Salicylate and Thymol are examples of a fully miscible liquid, a partially miscible liquid and a partially soluble solid in SASG, respectively. Isopropyl Myritate is more than 50% miscible with SASG, the miscibility of Methyl Salicylate is limited to 12-15%, the solubility of Thymol is between 4 and 5%.
Samples which contain Isopropyl Myristate and methyl salicylate have been prepared in the direct-1 mode using glass Petri dishes; in the case of methyl salicylate, this derivative is volatile, samples which are intended for Tack measurements must be prepared under the special conditions described above. In the case of Thymol, a variant of the indirect-1 mode has been used; this derivative is a solid with a melting point of 55° C.; in order to facilitate its solubilization in silicone gel, the following procedure is used: to each of the Parts A and B the appropriate quantities of Thymol are added; thus Parts A′ and B′ are obtained which contain the same quantities of Thymol; these Parts A′ and B′ are vialed; the stoppered flasks are placed for 20 minutes in a heated enclosure to 70°; each of the Parts A′ and B′ is then homogenized and kept in the stoppered flasks; after return to room temperature it is observed that Parts A′ and B′ are transparent and homogeneous. Parts A′ and B′ are used as described in the procedure relating to active derivatives of volatile character which has just been described in the case of methyl salicylate.
Thymol is crystalline Thymol supplied by Roth, Lot 14110049/B; Methyl Salicylate is the pure derivative supplied by Cooper, Lot 15050195/E; Isopropyl Myristate is supplied by Roth, Lot 306199473. These are also the same products that were used in all of the examples in Tables 3 to 15.
The results presented in Table 7 in
Table 8 in
The results shown in Table-8 show that the introduction of microparticles compensates for the effects of the presence of isopropyl myristate; while the presence of 4.8% Isopropyl Myristate causes the values of Tack and G′ to drop by 20% (see Table 7), the presence of Aeroperl 300-30 makes it possible to obtain SACSG containing from 6% to 23% Isopropyl Myristate whose values of Tack and G′ are greater than or equal to those of pure gel.
However, for a given amount of microparticles the amount of Myristate must not exceed certain limits beyond which the microparticles can no longer compensate for the effects of isopropyl Myristate additions as shown in the examples in Table 9 in Figure-8. These examples relate to compositions containing 55-89% RT Gel 4317, 4-13% Aeroperl 300-30 and 6-33% Isopropyl Myristate. The SACSG were prepared using the specific indirect mode 1 which is described for the tests shown in Table-8.
These results indicate that for this type of composition, the Total Impregnation Rate value must be less than 0.98-0.86 in order for the Tack and G′ values to be equal to or greater than those of the pure gel.
The same type of result is obtained with the Dow Corning VM 2270 microparticles reported in Table 10 in
Tests were conducted under conditions identical to those described for RT Gel 4317/Aeroperl 300-30/Myristate mixtures. The results are similar: it is possible to prepare compositions containing 23% Isopropyl Myristate whose performance will be at least equal to that of pure gel and the saturation rate value must remain below a limit value.
Tables 11 to 13 respectively in
Table 11 “RT Gel 4317/Sun PMMA-X/Isopropyl Myristate” The products for the characterization of Tack and G′ were prepared using indirect mode 1, but subjecting parts A′ and B′ to a 48-hour heat treatment at 70° to facilitate the distribution of isopropyl myristate.
The results show that all mixtures containing between 6-10% isopropyl myristate and 4.5-10% of the Sun PMMA-X microparticles have Tack and G′ values which are higher than those of the pure gel.
Table 12. RT Gel 4317/{Aeroperl 300-30/Methyl Salicylate}
These mixtures have been prepared in indirect mode 2 using Aeroperl 300-30 impregnated with methyl salicylate; the impregnation rates of Aeroperl 300-30 are 0.33, 0.47, 0.51 and 0.6. In the case of these mixtures the Impregnation Rates of the microparticles are equal to the Total Impregnation Rates. These tests have been carried out according to indirect mode 2, with the addition of a 24-hour heat treatment at 70° C. of Parts A′ and B′. In the case of the tests which were carried out with μP whose Impregnation Rate is less than 0.6, compositions are obtained which contain from 4.8 to 17.7% methyl salicylate and whose performance is equal to or better than that of pure gel. In the case of test SDE-161 which was obtained with pp whose Impregnation Rate is 0.6 only the value of Tack is higher than that of the gel; the value of the elastic component of the shear modulus, G′, is just 12% lower than that of pure gel.
Table 13: “RT Gel 4642/{Aeroperl 300-30+Thymol}/Isopropyl myristate: Table 13 shows the results that were obtained from compositions that contain:
RT Gel 4642/{Aeroperl 300-30+Thymol}/Isopropyl myristate mixtures are prepared according to indirect mode 2 by adding to each of Parts A and B the same quantities of impregnated microparticles and then isopropyl myristate. Parts A′ and B′ are subjected to a heat treatment at 40° for 24 hours in stoppered vials. The 2 mm films are prepared under the conditions described in the case where the SACSG contain volatile derivatives.
The mixture RT Gel 4642 and Thymol is prepared according to indirect mode 1 by adding the same quantities of crystalline Thymol to each of Parts A and B; Parts A′and B′ are then heated at 70° C. for 20 min in stoppered vials. The 2 mm films are also prepared under the conditions which are described in the case where the SACSG contain volatile derivatives.
These heat treatments melt the Thymol or promote the distribution of the constituents of the mixtures.
The results shown in Table 13 lead to findings similar to those made previously. The addition of 4.2% Thymol to RT Gel 4642 degrades the performance of the gel (test SDE 439). As shown in SDE 391, the presence of 7.9% microparticles makes it possible to obtain SACSG that contain a mixture of 13% Thymol and Isopropyl Myristate while developing performances that are at least equal to those of the pure gel; in the case of this test, the value of the Total Impregnation Rate is 0.66. In the case of test SDE-392 where the Total Impregnation Rate value is 0.83 the values of tack and G′ are lower than those of the pure gel; this result also shows that the Total Impregnation Rate value must be below a limit value.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1901480 | Feb 2019 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/053849 | 2/14/2020 | WO | 00 |
