Patent Application
20150025187
This invention is directed to a non-phthalate monobenzoate useful as a plasticizer or coalescent in a variety of polymer applications, including but not limited to architectural coatings, industrial coatings, OEM coatings, paints, enamels, lacquers, inks, overprint varnishes (“OPV's”), other coatings, polishes and the like, In particular, this invention is directed to the use of a monobenzoate ester, 3-phenyl propyl benzoate, in coatings applications, to provide compatibility, lower VOC content, and excellent film forming properties. Depending on the coatings application, the invention provides compositions that have comparable or better rheology, viscosity stability, compatibility, processability, gloss, hardness, scrub and rub resistance, water and alkali resistance, adhesion, color density, and film formation, among other advantages, over traditional plasticizers or coalescents.
The invention is also directed to polymeric compositions comprising the inventive monobenzoate, such as architectural and industrial coatings, paints, OEM coatings, special purpose coatings, OPV's, inks, nail polish, floor polish and other polymeric coatings.
In polymer-based coating compositions, the film-forming aid, i.e., coalescent, is a very important component. Coalescents allow film formation to occur at lower temperatures than the polymer without the coalescent would. Typically, about is the temperature to which a coalescent must reduce the minimum film formation temperature (MFFT) of a polymer. In the case of a polymer having an already low MFFT, the coalescent provides formation of a film with improved properties as compared to a film without the coalescent. In the case of polymers having high glass transition temperatures (Tg), coalescents allow film formation to occur at desired ambient conditions, whereas a continuous film would not form with such polymers without the coalescent.
Coalescents partition to the polymer in the emulsion and soften dispersed particles allowing them to fuse or form a continuous film. The coalescent will then partially or completely volatilize out of the film, depending on the coalescent, allowing the film to regain its original physical properties. Plasticizers, used as coalescents are less volatile and slower to come out of the film.
Besides facilitating continuous film formation at lower temperatures, coalescents are selected that improve the properties of the paint/coating film, such as gloss, scrub resistance, and block resistance. Coalescents are also selected based upon a variety of properties, including without limitation, volatility, miscibility, stability, compatibility, ease of use, and cost.
Plasticizers have been known and used for years in latex paints and other coatings, primarily for their excellent coalescent properties, In some instances, they are also desired for their plasticizer function at higher levels of use. A typical plasticizer softens a polymer and makes it more workable. It is also well-known that plasticizers can improve paint performance characteristics, such as mud cracking, wet edge and open time.
Of particular concern in selecting a plasticizer/coalescent for a coatings composition is the VOC content of the plasticizer/coalescent in the resulting film. By its nature, “escaping” or “volatilizing” coalescent contributes significantly to the VOC's of the film, beginning with the coalescing phase and lasting for a sustained period afterwards. This, in turn can affect the air quality around the film and be manifested as an unpleasant odor. Traditional coalescents are highly volatile and can contribute significantly to the VOC content of a paint or coating and have significant environment and health disadvantages, VOC's readily vaporize or evaporate into the air, where they may react with other elements or compounds to produce ozone. Ozone, in turn, causes air pollution and a host of health concerns including breathing problems, headache, burning, watery eyes and nausea, just to name a few.
VOC's are of particular concern in the paint and coatings industry in the manufacture and application of products containing VOC's. Use of VOC's in the manufacture of paint and coatings result in poor plant air quality and worker exposure to harmful chemicals. Persons who are exposed to VDUs may suffer from a number of health problems, including but not limited to several types of cancers, impaired brain function, renal dysfunction and other health problems.
Similarly, painters and other users of VOC-containing paints and coatings who are regularly exposed to harmful VOC vapors may suffer from health problems. VOC-containing products release harmful VOC's into the air as they dry, and become especially concentrated in indoor applications. Indoor VOC levels are routinely 10 times higher than outdoor levels and may be up to 1,000 times higher immediately after painting. Further, although VOC levels are highest during and soon after painting, they continue seeping out for several years. In fact, only 50 percent of the VOC's may be released in the first year. Accordingly, paints and coatings having high VOC content are considered health and environmental hazards, and regulations have been implemented to protect manufacturing workers and end-users.
Waterborne overprint varnishes (OPV's) and inks are specific types of coatings that have significant roles in the graphic arts industry. OPV's provide the finishing touch to printed media, protecting ink and printed matter for a wide variety of applications, including but not limited to books, magazines, packaging materials, and other printed matter. These clear coatings also provide visual effects in addition to protecting the underlying ink from damage.
Various OPV's and inks exist having a wide range of compositions. OPV's and inks are selected for use based upon the printing process to be utilized and volume of use OPV's most commonly comprise three forms: waterborne, UV-curable polymeric dispersions, or other solution (solvent) polymers. Waterborne OPV's are all based on polymeric dispersions having a variety of compositions and glass transition temperatures (Tg). A classic type of polymer used in polymeric dispersions, such as OPV's, is a hard styrene acrylic, which has excellent gloss and durability characteristics.
OPV's are often exposed to harsh conditions during processing and in use, yet must look perfect when finally placed on display. Hence, OPV's may contain various other additives to impart rub resistance and scratch and abrasion resistance. Still other additives may be selected to facilitate the formation of an effective barrier to moisture, oils or other soils and to improve heat resistance. The choice of additive may depend on the final use intended for the graphic art media prepared using an OPV and the volume of that anticipated use.
Many types of inks are utilized in the graphic arts industry to fit the various printing processes. Like OPV's, waterborne inks often comprise polymeric dispersions. Inks are often “coated” or protected with OPV.
As with architectural coatings (paints) and industrial coatings, formation of a continuous film that achieves proper performance is important in graphic arts applications. Waterborne OPV's and inks are coatings that may require a plasticizes/coalescent for proper film property development. Older generation polymeric systems used in OPV's have very high glass transition temperatures. These older generation systems, who not necessarily film formers at room temperature, provided excellent performance for different applications. To assist in the development of performance properties in these harder systems, the graphic arts industry utilizes coalescents to assist in film formation in waterborne OPV's and inks. These coalescents have also typically been the more volatile types. While they function well, VOC content is an issue with these types of coatings as well.
New generation polymer emulsions used in OPV's and inks seem to be following the same trends that are found in other coatings. These systems are softer and may not necessarily require any coalescent or plasticizer to form a film under their conditions of use. Heat and/or air flow may be employed to assist in coalescence in graphic arts. However, these approaches to coalescence may result in poor performance properties and their use is thus limited.
Traditional coalescents for paint include the traditional industry standard film-forming aid, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TXMB). Other coalescents of choice in different coating industry segments include glycol ethers. All of these are invariably 100% volatile by the EPA 24 D2369 volatility test, a method of VOC determination used for paint and other coating systems. The monobenzoate, 2-ethyl hexyl benzoate, has been used as a coalescent in OPV's and waterborne inks and is functional, but it still has a fairly high VOC content.
Consumers are demanding safer alternatives, and coatings formulators continue to be faced with the challenge of reducing VOC's, while, at the same time providing a coating with required performance characteristics. Most often, formulators reduce the amount of the most volatile components used in the coatings or replace them with lower VOC content components, both of which reduce VOC concerns to some extent, but may result in compromised performance. Other approaches are to use soft polymers with no coalescent (with the sacrifice of performance in some instances), reduction or elimination of glycols used for antifreeze and tooling, or the use of a low VOC plasticizer or coalescent.
Plasticizers are useful coalescents for waterborne systems as they have low VOC contribution; however, they impart greater permanence, i.e., they are slower to leave film, and thus less volatile. In some instances, the permanence of plasticizers can be a detriment. In using plasticizers as coalescents, a balance must be struck between greater permanence—and thus lower VOC's—and good final film properties. Desirably, a low VOC content paint or coating should have at a minimum, equivalent performance to paints or coatings having higher VOC content. Toward that end, raw material suppliers continue to develop new, lower VOC products for use in paints and coatings, which do not compromise performance.
Plasticizers traditionally used in the coatings industry (including graphic arts applications), include di-n-butyl phthalate (DBP), diisobutyl phthalate (DIBP) or butyl benzyl phthalate (BBP). These plasticizers were used when a true plasticizer was required, as is the case when polymers with high Tg's are employed in one application or another. DBP and DIBP have a lower VOC content than traditional coalescents, but are still somewhat volatile, while BBP has a very low VOC content. Apart from VOC content, however, phthalate ester use has some disadvantages, as DBP and BBP uses, in particular, are restricted due to regulatory concerns.
Dibenzoate plasticizers have well known utility in coatings. Dibenzoates by their nature are non-phthalates and do not have the restrictions or health concerns associated with phthalates. Benzoates are historical alternatives for the graphic arts industry. Classic dibenzoates used as coalescents include DPGDB as well as blends of DEGDB and DPGDB. Commercial examples of benzoates include K-Flex® DP (DPGDB), K-Flex® 500 (DEGDB/DPGDB blend), K-Flex® 850S (a newer grade of DEGDB/DPGDB blend), and K-Flex® 975 P (a new triblend comprising DEGDB/DPGDB/1,2-PGDB), among many others.
Monobenzoate esters known to be useful as plasticizers include: isodecyl benzoate (IDB), isononyl benzoate (INB), and 2-ethylhexyl benzoate (BIB). For example, isodecyl benzoate has been described as a useful coalescent agent for paint compositions in U.S. Pat. No. 5,236,987 to Arendt. The use of 2-ethylhexyl benzoate in a blend with DEGDB and diethylene glycol monobenzoate is described in U.S. Pat. No. 6,989,830 to Arendt et al. The use of isononyl esters of benzoic acid as film-forming agents in compositions such as emulsion paints, mortars, plasters, adhesives, and varnishes is described in U.S. Pat. No. 7,638,568 to Grass at al.
“Half ester” monobenzoates include dipropylene glycol monobenzoate and diethylene glycol monobenzoate, which are byproducts of the production of dibenzoates, but which, most of the time, are not objects of production. Half esters are not known for being high solvators and are less compatible than the corresponding dibenzoate in PVC. However, the half esters are compatible with emulsion polymers, such as acrylic and/or vinyl ester polymers, which are commonly used in paint and coatings applications.
There remains a need for non-phthalate, low VOC plasticizers and coalescents for use in coatings applications. Such alternatives should be compatible with a wide variety of polymers and have lower VOC content and comparable or better performance properties when used in coating applications traditionally requiring plasticizers and/or coalescents. Non-phthalate, low VOC alternatives are particularly desirable in view of the environmental, health and safety issues associated with many traditional plasticizers and coalescents.
It has been discovered that an entirely different monobenzoate, 3-phenyl propyl benzoate (3-PPB), is a surprisingly effective lower VOC plasticizer alternative, as compared to TXMB, IDB or INB, for use in polymeric applications, including but not limited to paints and other coatings, OPV's and inks. Advantages of this monobenzoate, besides lower VOC's, are its excellent health, safety and environmental profile and handling properties, which are better than most dibenzoates and monobenzoates previously used. This new monobenzoate is not classified as hazardous under any “hazard” class, and no labeling elements are required.
The monobenzoate, 3-PPB, has not been utilized in polymeric applications of the type discussed herein in the past. It has been used and continues to be used in flavoring and fragrance applications. It has also been used as a solubilizer for certain active or functional organic compounds in personal care products as described in U.S. Patent Publication 2005/0152858.
While this invention is focused on the use of the inventive plasticizer in paints and other coatings, other applications for the inventive monobenzoate include plastisols, adhesives, sealants and caulks, which are the subject of co-pending applications.
It is an object of the invention to provide a non-phthalate plasticizer/coalescent having excellent compatibility with a wide variety of polymers and a lower VOC content than traditional plasticizers or coalescents, for use alone or in combination with other plasticizers/coalescents in paints, architectural coatings, industrial coatings, OEM coatings, special purpose coatings, lacquers, enamels, OPV's, inks, polishes and other polymeric coatings where plasticizers and coalescents are traditionally required.
It is a further object of the invention to provide a monobenzoate useful as a coalescent in polymeric dispersions, such as OPV's and inks, which has a lower VOC content and achieves comparable or better performance than traditional coalescents, including but not limited to compatibility, gloss, hardness, water and alkali resistance, adhesion, dry to touch time, color density and film formation.
Yet another object of the invention is to provide a monobenzoate useful as a coalescent in polymeric dispersions, which has a lower VOC content and achieves comparable or better performance than traditional coalescents, including but not limited to efficiency and compatibility when used in traditional latex emulsions or other polymeric coatings.
It is a further object of the invention to provide a polymeric emulsion coating having a low VOC content and improved performance properties, including without limitation viscosity, hardness, gloss, block resistance, scrub and rub resistance, chemical resistance, dry time, open-time/wet edge, mudcrack resistance, and heat age stability over that achieved with current low VOC emulsion coatings.
It is yet another object of the invention to provide a low VOC content polymer emulsion coating that is environmentally friendly, safe to handle and not subject to regulatory control.
Still a further object of the invention is to provide a monobenzoate plasticizer, useful as a plasticizer alone or in a blend of plasticizers, for use in paint or other polymeric coatings, which has a lower VOC content and comparable or better performance than traditional coalescents.
Other objects of the invention will be apparent from the description herein.
This invention is directed to a non-phthalate benzoate plasticizer useful as coalescent for polymeric dispersions, such as architectural coatings (paint), industrial coatings, OPV's, inks, and polishes, among others. In particular, the invention is directed to the use of a new monobenzoate, 3-phenyl propyl benzoate (3-PPB), component not previously known or used as a plasticizer or coalescent for coating applications.
Use of the inventive monobenzoate in the same or similar amounts as traditional plasticizers/coalescents results in a lower VOC content and comparable or better performance and handling properties than that achieved with traditional plasticizers or coalescents. The inventive monobenzoate has low toxicity and does not have the environmental, health and safety issues associated with traditional phthalate plasticizers or coalescents.
In one embodiment, the invention is a non-phthalate coalescent, 3-PPB, useful in coatings applications to aid film formation and improve properties such as viscosity, gloss, block resistance, scrub and rub resistance, chemical resistance, dry time, open-time/wet edge, mudcrack resistance, and heat age stability. In another embodiment, the invention is an architectural coating, paint, industrial coating, OEM coating, special purpose coating, lacquer, enamel, OPV, ink, nail polish, or floor polish, comprising 3-PPB.
In a further embodiment, the invention is a variety of aqueous or non-aqueous polymer compositions comprising 3-PPB.
In still another embodiment, the invention is a blend of 3-PPB with other plasticizers and coalescents, including solid plasticizers, for use in paint, OPV's, waterborne inks, colorants, and other coatings.
a) and (b) show the heat age stability of the vinyl acrylic flat paint, both Delta Viscosity and Delta E color shift results, respectively, for the plasticizers/coalescents evaluated.
The present invention is directed to a monobenzoate plasticizer useful as a primary or secondary plasticizer/coalescent for aqueous and non-aqueous based polymer coatings, including but not limited to architectural coatings (paint), industrial coatings, OEM coatings, special purpose coatings, OPV's, inks and polishes. The benzoate plasticizer comprises a unique monobenzoate, 3-phenyl propyl benzoate (3-PPB), a known flavor and fragrance component, not previously known or used as a plasticizer or coalescent in polymeric coatings.
The inventive monobenzoate plasticizer can generally be utilized as a primary plasticizer, a secondary plasticizer in blends with other plasticizers, or a coalescent with numerous polymeric dispersions, often as a substitute or alternative for conventional plasticizers/coalescents having a higher VOC content. Any of the known polymers that can be formulated into an architectural coating (paint), industrial coating, OEM coating, special purpose coating, nail polish, OPV, ink, floor polish or other similar polymeric coating can be used in combination with the inventive monobenzoate to prepare a low VOC content composition in accordance with the present invention.
Polymers useful to prepare the polymeric dispersions discussed herein are known in the art. The inventive composition is expected to be useful with a wide variety of polymers, including both waterborne and non-aqueous-based polymer compositions. Suitable polymers include, but are not limited to: various vinyl polymers, such as polyvinyl chloride and copolymers thereof, vinyl acetate, vinyl acrylates, vinyl chloride co- and ter-polymers, vinylidene chloride, diethyl fumarate, or diethyl maleate various polyurethanes and copolymers thereof: cellulose nitrate; polyvinyl acetate and copolymers thereof; various polyacrylates and copolymers thereof, and various esters of versatic acid.
Acrylic polymer compositions for various applications may also be used with the inventive monobenzoate and include various polyalkyl methacrylates, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, or allyl methacrylate; or various aromatic methacrylates, such as benzyl methacrylate or styrene acrylate; or various alkyl acrylates, such as methyl acrylate, ethyl acrylate, butyl acrylate, or 2-ethylhexyl acrylate; or various acrylic acids, such as methacrylic acid and other styrenated acrylics.
Other polymers for which the inventive monobenzoate may be useful as a plasticizer include epoxies, polyamides, and nitrocellulose. Still other polymers will be evident to one skilled in the art.
Use of the inventive monobenzoate is not limited to any particular polymer. Although the invention is described primarily with respect to paint, OPV and ink applications, the inventions is not limited as such. Other polymer-based coating compositions requiring plasticizers and/or coalescents and/or where plasticizers and/or coalescents are traditionally utilized, are known to one skilled in the art. The novel monobenzoate of the present invention may be used as a low VOC substitute or alternative for various traditional polymeric dispersions.
The total amount of the inventive monobenzoate used in any particular polymeric dispersion would range broadly depending on the particular polymer, the characteristics of the polymer and other components, the process, the application or use and the results desired. Exemplary amounts for plasticizers/coalescents are included in the examples and further described generally herein.
Generally, the amount of coalescent required for a polymeric dispersion is based on the MFFT of the base polymer and may be used in an amount sufficient to form a film at room temperature. The harder the polymer (higher MFFT and Tg), the more plasticizer/coalescent required.
In paints or coatings, plasticizer/coalescents can be used in amounts up to about 20% of the polymer solids in the system, depending on the particular polymer.
In OPV's and inks, coalescents may be utilized in amounts up to about 20 wt. %, based upon the total weight of the overprint varnish or ink. Exemplary amounts may range from about 2% to about 8% wet.
Useful amounts of 3-PPB are set forth in the examples. It is expected that one skilled in the art would be able to arrive at additional acceptable amounts for other applications, based on the intended use and desired performance in the particular polymeric application.
Other applications for the inventive monobenzoate include nail polish, floor polish, OEM coatings, and special purpose coatings. For nail polish products, in particular, phthalates have been used for at least a decade, and certain dibenzoates have also been utilized for several years, wherein the advantages attributable to coalescents discussed herein are desired.
The inventive monobenzoate may be, but is not required to be, blended with various other conventional plasticizers to enhance or augment properties of polymer compositions. Conventional plasticizers have been described herein and include, but are not limited to phthalate esters up to C5, phosphate esters, polyesters, citrates, isobutyrates, sulfonamides, sulfonic acid esters, terephthalate esters up to C4, epoxy plasticizers, benzoate esters, including both di- and mono-benzoates, or mixtures thereof.
The inventive monobenzoate may also be blended with solid plasticizers, such as sucrose benzoate, dicyclohexyl phthalate, triphenyl phosphate, glycerol tribenzoate, 1,4-cyclohexane dimethanol (CHDM) dibenzoate, pentaerythritol tetrabenzoate, alkyl glycol esters, or mixtures thereof.
The inventive monobenzoate may be combined with or include various amounts of conventional additives such as oils, diluents, antioxidants, defoamers, surfactants, heat stabilizers, flame retardants, surfactants, waxes, solvents and the like, depending on the particular coatings application. Additives amounts can generally vary widely and often range from about 0.1 to about 75 parts by weight for every 100 parts by weight of the coating composition.
By way of example, traditional OPV's, in addition to the coalescent, comprise a dispersion of a high Tg (>10° C.) polymer, wax dispersions, various high Tg resins, surfactants, defoamers, and water. Traditional inks, in addition to the coalescent, comprise similar components as an OPV, but with added pigments for color.
Other useful components for the various polymer applications are known to one skilled in the art. Exemplary simple basic OPV's and inks and paint formulations are set forth in the examples.
The inventive monobenzoate provides a lower VOC content alternative over many traditional coalescents and, depending on the application, provides comparable or better compatibility, viscosity stability, rheology, film formation, gloss, water and alkali resistance, dry to touch time, open time, scrub and rub resistance, color density, adhesion, peel strength and hardness, among other advantages. In many instances, the inventive monobenzoate outperforms industry standard coalescents, regardless of VOC content, including traditional and newer dibenzoate blends. The monobenzoate is particularly useful as a coalescent when considering the use of harder polymers as alternatives to softer polymers in a variety of low VOC formulations.
The invention is further described by the examples set forth herein,
The evaluation of the plasticizers/coalescents consisted of a variety of experiments. First, VOC's of the neat plasticizers/coalescents selected were determined. Then, effectiveness and efficiency of the coalescents with a traditional polymer were determined using simple binary blends.
In another segment, a starting basic OPV formulation was prepared to assess the effect of the new plasticizer in an actual OPV. In yet another segment, the coalescent performance in a simple waterborne model ink formulation was evaluated. Inks were then coated with the experimental OPV's and evaluated.
Other evaluations involved the use of the inventive monobenzoate in adhesives and plastisols and are set forth herein below.
The polymer selected for use in the OPV/ink examples was a traditional high Tg, hard styrene acrylic emulsion a standard in the graphic arts industry, although it is expected that the present inventive coalescent would be useful in a large number of polymeric dispersions used in this industry. Such polymers would be known to one skilled in the art. The polymer was utilized in all of the simple starting formulations set forth herein.
The following plasticizers/coalescents were selected for evaluation in the examples (in whole or part):
The plasticizers/coalescents and TMPDMB are not soluble in water but the DPM, BCL and C are completely or partially soluble in water. It is expected that the water insoluble plasticizers/coalescents will partition to the polymer in the dispersion.
The following raw materials were used in the formulations prepared for Examples 1-4:
Raw Materials
Tests Utilized
The Following Tests were Employed:
Test Methodology
Specific Details of the Test Methods are Described Below:
Volatility: ASTM D2369 used. A TGA isothermal for one hour under air at 110° C. was also employed.
Viscosity Response: Both the initial and 24 hour viscosities were measured. Viscosity measurements were made using a Brookfield RVT at 20 RPM's for 10 revolutions at 23±2° C.
MFFT (Minimum Film Formation Temperature): The MFFT's were measured with a Rheopoint MFFT 90 under air. ASTM D2354-10 employed.
Gloss: The gloss of the substrate or the print was measured at 20° and 60° with a Micro-TRI-Gloss II Meter. ASTM D523 employed.
Water Resistance: Two drops of distilled water was applied to the print, covered with a watch glass, and timed for 2, 5 or 10 minutes. After the allotted time, the water was removed gently with a folded Kimwipe. The punt and Kimwipe™ tissue were examined and rated, The rating was: 5—no effect; 4—slight blush; 3—blush; 2—partial break; 1—total break in film.
Alkaline Resistance: Two drops of alkaline solution (Clorox® Formula 409) was applied to the print, covered with a watch glass, and timed for 2, 5 or 10 minutes. After the allotted time, the solution was removed gently with a folded Kimwipe™. The punt and Kimwipe™ were examined and rated. The rating was 5—no effect; 4—slight blush: 3—blush: 2—partial break; 1—total break in film.
Rub Resistance: Rub resistance was evaluated using 5 layers of cheesecloth under a 1 kg weight. The cheesecloth and the weight were rubbed against the ink or the OPV covered ink 100 times. The cheesecloth was then evaluated and rated. The rating was—5—no effect; 4—slight blush; 3—blush; 2—partial break; 1—total break in film.
Hardness: The OPV was coated on an aluminum panel using a 3 mil drawdown. Samples were then dried for 4 hours and tested using a Konig Pendulum Tester. Samples were tested 4 hours, 24 hours, 3 days and 7 days after preparation. ASTM D4366 employed.
Adhesion to Prints: Scotch tape was pressed firmly to the print surface and then pulled off at a 90° angle as fast as possible while holding the print down. ASTM D3359-9
Optical Density and Color of Ink: The optical density (color strength) of the prints was measured with an X-Rite Color 17 spectrophotometer. ASTM D2066 employed.
Viscosity of Ink: The viscosity of the ink prepared was determined with a TA AR2000ex rheometer. Two centimeter plates with a gap of 100 microns were used at 25° C. The shear rate was 100 sec−1.
Basic Preparation/Applications—Processes and techniques utilized in the evaluations are described in more detail below:
Formulation Preparation:
Diblend Formulations: Made by adding the coalescent slowly to the emulsion at 500 RPMs using a high speed mixer equipped with a Jiffy blade. Once the coalescent was added, the speed was increased to 750 RPM for a total mix time of 30 minutes.
Basic OPV Formulations: Prepared by adding the individual components in order to the mixing vessel while mixing at 500 RPM's using a high speed mixer equipped with a jiffy blade. The coalescent was the last to be added. This mixture was stirred for a total of 5 minutes at 500 RPM's after the add of the last component, then the speed of the mixer was increased to 750 RPM's for an additional 5 minutes.
Waterborne Phthalol Blue Flexographic Dispersion Ink: Individual components were added together slowly in the order listed with the wax dispersion added last. The ink was stirred with a high speed mixer at 500 RPM's with a jiffy blade for 5 minutes.
Test Panel Sample Preparation Conditions:
The gloss, water resistance, alkaline resistance, rub resistance and adhesion to the prints were evaluated both when the prints were first made, and after aging for 3 days. The OPV was applied with a #6 Mayer wound rod, depositing approximately 15 μm wet film on a 3B Leneta card, a clay coated board or over a blue flexographic ink on a 3B Leneta card, oxidized polypropylene film or clay coated board.
Hand Proof Preparations:
The inks were drawn down with a Flex® Hand-proofer with a 180 pyramid cell anilox roll on 3B Leneta cards, clay coated boards and the treated polypropylene film. The ink was air dried and then dried in an oven three times for 30 seconds at 70° C.
OPV Over Ink Preparations:
The OPV was applied as above over the hand proofs and was air dried, then dried in an oven three times for 30 seconds at 70° C. Each OPV was matched with the corresponding ink in every case.
Of the benzoate coalescents evaluated, other than 2-EHB, the TGA scan data shows that the monobenzoate of the invention, X-613 (3-PPB), was the most volatile, However, X-613 was significantly lower in VOC content than the older traditional high VOC coalescents. All of the plasticizers/coalescents of the evaluation were considerably lower than 20% volatile compared to the ethers, TMPDMB and 2-EHB.
For this example, the binary blends evaluated are shown below.
Coalescents were incorporated in a base emulsion at the level of use in a basic starting OPV formulation (4%) to observe the effect of just the coalescent on the base polymer. The important tests to evaluate how coalescents affect the polymer are: viscosity response (indicates interaction and swelling of the polymer), minimum film formation temperature (MFFT), and water reduction.
Viscosity Response
The viscosity response of the base emulsion is indicative of the compatibility of the water insoluble coalescents tested.
Water Reduction
As the viscosity of an OPV is normally reduced to a constant value to allow the application at the same viscosities, the amount of water required to get the desired viscosity was determined and is illustrated in
MFFT
As the MFFT of the binary blends were significantly higher than room temperature, it was decided to prepare blends with 6 and 8% wet plasticizer levels and determine their MFFT's. The results of that testing are illustrated in
The data developed were quite interesting and somewhat unexpected. The mono and dibenzoates decreased the MITT significantly as might be expected. Interestingly, the films formulated with TMPDMB had significantly higher MFFT's at all coalescent levels than the other films. It was also noted that the TMPDMB films were especially difficult to read on the MFFT bar due to the mottled film quality caused by the poor compatibility of TMPDMB with the styrenated acrylic polymer emulsion. Because of this obvious incompatibility, the use of TMPDMB was discontinued for the remaining segments of the evaluation. The Carbitol and Butyl Cellusolve neither increased nor decreased MFFT. This would suggest a degree of incompatibility with the base polymer. X-20 (dibenzoate triblend) seemed to be particularly effective in MFFT suppression as was X-613 (the inventive monobenzoate). This effect has been noted in other polymers.
The next step in this evaluation was to see if the experimental plasticizers/coalescents can perform as required in a basic starting formulation at the level of test in the binary blends.
Viscosity Response
Plasticizers/coalescents (at a level of use of 4%) were incorporated in the basic starting formulation listed in Table 1. The viscosity response and dry film properties were determined.
The viscosity response of the base emulsion is indicative of the compatibility of the plasticizer/coalescent tested.
The viscosity response to select dibenzoates in the OPV formulation with 6% coalescent instead of 4% was also measured. Both the X250 and X-20 OPV's had viscosity of 250 mPa·s, which demonstrated that a relatively low add level (increase of 2%) had a significant impact on OPV viscosity with these types of plasticizers/coalescents.
MFFT
Table 2 lists the MFFT's obtained for the OPV formulations. All of the formulations formed films well at room temperature conditions. The water soluble coalescent types were more effective in MFFT suppression. As the MFFT depression Was somewhat less for the dibenzoates than the ethers, the MFFT's of OPV's with loading at 6% wet on the two dibenzoate blends discussed above (X250 and X20) were also determined. These results are also listed in Table 2 and indicate that less than an additional 2% would be necessary to achieve results similar to the ethers. Most likely, 2% additional plasticizer would not be necessary to achieve the desired development of full performance characteristics.
Dry Time
One question addressed with respect to the use of real plasticizers instead of a volatile coalescent was the effect on parameters such as dry time. The dry to touch time of the OPV's was determined and is shown in
Gloss
Water and Alkali Resistance
Tables 3, 4 and 5 list the water and alkali resistance of the evaluation OPV's. The water resistance initial 1 day OPV on Leneta 3B charts was not nearly as good as the films aged for 3 days. The initial water resistance of the benzoate plasticized films were not as good as could be expected, as plasticizers will normally improve the water resistance of a film. Other factors in the formulation seem to come to bear in the OPV. After three days the water resistance was improved. On the clay coated board the benzoate films have good initial water resistance.
In the case of alkali resistance the properly coalesced films seemed to function marginally better than the film without coalescent or plasticizer.
Hardness
Basically a waterborne ink is an OPV with color added. Inks were prepared based on each coalescent/plasticizer using the basic formulation set forth in Table 6 below.
The ink was used under an OPV having the same coalescent/plasticizer type. In each case, plasticizer/coalescent was present at 4% in the ink and the OPV. The focus of this example is on the inventive monobenzoate, X-613.
The viscosities obtained for the inks were 317 mPa·s for the “no coalescent” ink, 758 mPa·s for X-613 ink, 411 mPa·s for DPM ink and 251 mPa·s for the C ink. Again, lower viscosities were noted for the inks having water soluble coalescent.
Tests were conducted on prints made with a hand proofer. Gloss, rub resistance, adhesion and color density on the ink were performed after the OPV was paced over the ink and dried.
Gloss
Table 7 lists the gloss data obtained on the OPV over ink. Plasticizers/coalescents improve gloss. X-250 was the best of the plasticizers in this respect and similar to the ether coalescent.
Rub
Table 8 lists the rub data obtained for the inks and the inks coated with OPV on Leneta 3B and on a polypropylene film, The OPV significantly improved the rub resistance of the film. No significant differences in the performance between the evaluation ink and OPV's was noticed.
Adhesions
Tables 9, 10 and 11 list the tape adhesion data obtained for the OPV/ink. On the sealed substrate, the coalesced films seem to function better, both initially and after 3 days of dry. The aged films performed well on the clay coated stock.
Color Density
The Dc obtained for the inks did not vary much. They ranged from 1.23 to 1.28 for the evaluation of OPV over ink.
The foregoing examples illustrate basic screens for use of low VOC coalescent/plasticizers in binary blends, OPV's and inks. The inventive dibenzoate, X-613, has demonstrated that it is an excellent lower VOC plasticizer/coalescent. It is also a non-phthalate and a non-ether.
Of the control coalescents tested, it would appear that the traditionally used TMPDMB is not a good choice for these types of OPV's and waterborne inks as it had limited compatibility with the base polymer that was used. The BCL and C were also limited in compatibility and utility.
A semi-gloss acrylic (Rhoplex™ SG-30) and a vinyl acrylic flat paint (UCAR® 379 G) were tested.
Listed below are the key parameters of the coatings:
The following coalescent/plasticizers were evaluated:
Paint/Coating Testing
The Paint Evaluations Consisted of the Following Determinations:
Physical Properties, including WPG, pH, gloss, and Hide.
Performance Properties, such as block resistance, scrub resistance, dry-time open-time/wet edge, heat age stability, low temperature touch-up, low temperature porosity, mudcrack resistance and freeze-thaw stability.
Details of the test methods are listed in Table 12, below:
Table 13 below shows the physical property determinations for the semigloss acrylic using the above noted plasticizers/coalescents and a blank.
The results show equivalent performance for 3-PPB as compared to several coalescents, including an industry standard coalescent and one claimed to have low VOC content (TEGDO).
Table 14 below shows the rheology results of the semigloss acrylic for the various plasticizers/coalescents evaluated.
Again, the results show that 3-PPB had equivalent performance.
Table 15 shows the HIDE results of the semigloss acrylic. HIDE results reflect the ability of the coating to cover the substrate completely.
Table 16 below shows the dry time in minutes of the semigloss acrylic for the evaluated plasticizers/acrylics. While faster is good, that must be balanced against open time. Results show that 3-PPB performed similarly to the other evaluated plasticizers/coalescents.
Table 17 below shows the low temperature film formation/porosity results of the semigloss acrylic for the plasticizers/coalescents evaluated. The results show a performance advantage for 3-PPB.
Freeze-thaw stability results of the semigloss acrylic showed freeze-thaw stability failure in all samples.
Tables 18, 19 (rheology) and 20 (HIDE), below, show the physical properties of the vinyl acrylic flat paint for plasticizers/coalescents evaluated. The results show no differences among the various plasticizers/coalescents evaluated.
Table 21 below reflects the dry time results of the vinyl acrylic flat paint for the plasticizers/coalescents evaluated. While 3-PPB had a longer dry time, that may be an advantage for wet edge/open time results.
Table 22 shows the low temperature film formation/porosity results of the vinyl acrylic flat paint for the plasticizers/coalescents evaluated. Results show that all the plasticizers/coalescents performed better than the blank. 3-PPB performed well, but not quite as good as the other samples, indicating that it was not as efficient in film formation in vinyl acrylic flat paint.
Freeze-thaw stability results for the vinyl acrylic flat paint showed freeze-thaw stability failure in all samples.
The foregoing results demonstrate that 3-PPB is a viable low VOC alternative for use as a plasticizer/coalescent in polymeric coating applications.
In accordance with the patent statutes, the best mode and preferred embodiments have been set forth; the scope of the invention is not limited thereto, but rather by the scope of the attached claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US13/26083 | 2/14/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61598372 | Feb 2012 | US |
