Formulation for Self-Curing Artificial Fingernails Containing Methoxyethyl Methacrylate

United States Patent [191 Lee, Jr. [54] [75] [73] [21] [22] [51] [52] [581 FORMULATION FOR SELF-CURING ARTIFICIAL FINGERNAILS CONTAINING METHOXYETHYL METHACRYLATE Inventor: Henry L. Lee, Jr., Pasadena, Calif. Assignee: Lee Pharmaceuticals, S. El Monte, Calif. Appl. No.: 148,735 Filed: May 12, 1980 Int. Cl.3 .......................................... .. C08F 265/06 U.S. Cl. ............................... .. 525/303; 260/ 17 A; 260/42.52; 424/61; 428/500; 525/79; 525/259; » 525/939; 260/31.2 MR Field of Search ..................... .. 525/303, 259, 939; 526/320; 260/17 A, 31.2 M; 424/61 [1 1] 4,260,701 [45] Apr. 7, 1981 [56] References Cited U.S. PATENT DOCUMENTS 2,654,717 10/ 1953 Rehberg et al. ................... .. 526/320 3,539,533 ll/1970 Lee et al. ................... .... .. 260/47 3,647,498 3/1972 Dougherty ......................... .. 117/8 4,104,333 8/1978 ‘Lee et al. ........................... .. 525/309 Primary Examiner—Carman J. Seccuro Attorney, Agent, or Ft'rm—Irons and Sears [57] ABSTRACI‘ Improved composition for a fingemail coating having an acrylic binder, a peroxide catalyst, a tertiary amine accelerator, and a polymeric filler at least partially solu- ble in the coating. The acrylic binder contains a mono- ethylenically unsaturated monomer comprising at least a major proportion of methoxyethyl methacrylate. A polyfunctional monomer may be present that copoly- merizes with the monoethylenically unsaturated mono- mer, for crosslinking and toughening. 18 Claims, No Drawings 4,260, 701 E FORMULATION FOR SELF-CURING ARTIFICIAL FINGERNAILS CONTAINING METHOXYETHYL METHACRYLATE FIELD OF THE INVENTION This invention relates to compositions useful for forming coatings on human nails. More particularly, the invention relates to self-curing coatings that can be applied to human nails to form decorative and protec- tive coatings, and/or artificial fingernails. BACKGROUND OF THE INVENTION Artificial nail compositions are described in U.S. Pat. No. 4,104,333, granted Nov. 15, 1977, and assigned to Lee Pharmaceuticals. In these compositions, the cur- able binder is a combination of at least two monomers, one of which is a monofunctional acrylate, preferably either tetrahydrofurfuryl acrylate or tetrahydrofurfuryl rnethacrylate, and the other of which is a polyfunctional carboxylate. Formulating such an artificial nail coating composi- tion is very challenging. Tne composition must be cur- able, once mixed, within a time period that is acceptable to the consumer. As a practical matter this means that curing must occur within about 120 to about 400 sec- onds after mixing and application. In addition, for great- est convenience and acceptability, curing must occur under ambient conditions to which.the nail is normally exposed including ambient temperature and normal atmospheric conditions. When cured, the coating must have sufficient adhe- sion to the substrate nail to resist mechanical removal. It must be strong and hard, like the natural nail. At the same time, it must be sufficiently flexible so that it can withstand the normal stresses to which human nails are ordinarily subjected, without cracking or breaking, and it must be removable at will in a reasonably convenient way. Formulating a nail coating composition or artificial nail composition that has all of these characteristics, especially freedom from brittleness, is very difficult. In US. Pat. No. 4,104,333, certain dibenzoates and phthal— ates or diphthalates are suggested for use as flexiblizers. Such components add to the cost of the formulation, and while imparting a certain degree of flexibility, di- lute the binder and filler, and thus require an added LIA 10 15 20 25 30 35 40 45 degree of formulating skill to balance the proportions of 50 the ingredients in order to obtain the desired physical characteristics in the cured article. BRIEF SUMMARY OF THE INVENTION This invention is concerned with compositions that are suitable for application to the nails, especially human fingernails, that cure rapidly, after application, under ambient conditions. These compositions may be used as decorative coatings to mend natural and artific- ial nails, or to create artificial fingernails. Compositions in accordance with the present inven- tion have a liquid resin binder comprising an acrylic resin; a peroxide catalyst—tertiary amine accelerator curing system; and polymeric filler that is at least par- tially soluble in the composition. The liquid resin binder comprises a monofunctional monomer comprising me- thoxyethyl methacrylate, and may also contain a poly- functional carboxylate that is copolymerizable with the 55 60 65 2 monofunctional monomer and that serves as a cross- linker. DETAILED DESCRIPTION on THE INVENTION Generally, the invention embraces compositions suit- able for application to a fingernail as a hardenable coat- ing or to form an artificial nail, having a particular kind of acrylic binder, a peroxide catalyst and t-amine accel- erator curing system, and containing polymeric filler that is at least partially soluble in the composition. The composition is formulated and the catalyst and the ac- celerator are present in such quantities to cause self-cur- ing to occur in situ, preferably within about 4-00 seconds after mixture of the ingredients and application to a nail, under ambient conditions to which the nail is normally exposed. The acrylic binder consists of a mixture of the following ingredients, by weight based on the total weight of the acrylic binder: (a) from about 0% to about 20% of a polymerizable, ethylenically polyunsaturated monomer that can form a v cross—linked polymer upon polymerization during cur- ing of the composition, which monomer contains in its molecule at least two groups that are capable of being addition polymerized upon contact with a peroxide- type free radical initiator and a tertiary amine—type accelerator, the polymerizable groups being members of the group consisting of allyl, acryloyl, methacryloyl, and combinations thereof, and (b) a second monomer that is monoethylenically un- saturated, in an amount from about 80% up to about 100%, that copolymerizes with the first monomer upon self-curing of the composition to form a copolymeric structure that is cross-linked, the second monomer com- prising in major proportion methoxyethyl methacry- late. Preferably, the acrylic binder consists of from about 0% to about 15% of a cross-linkable monomer such as one selected from the group consisting of ethylene gly- col dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, tris-propylene glycol dimethacrylate, and mixtures thereof, that are capable of being polymer- ized upon contact with a peroxide-type free radical initiator and a t-amine-type accelerator; and from about 85% to about 100% of methoxyethyl methacrylate. When the cross-linkable monomer forms up to 20% of the acrylic binder, the set time is easily adjusted to be within desired limits, through adjustment of the amounts of catalyst and accelerator; when it is in the range from 0% to 15%, the desired physical properties are more readily obtained. A polymeric filler, prefera- b‘ly one soluble in the monomer, is generally added to produce a coating composition that cures to have de- sired physical properties. A high loading with a poly- meric filler often will produce a cured coating having properties within desired limits even when little or no cross-linker is employed. The formulation should preferably be such that after curing, it exhibits a flexible modulus of rupture of at least 500 kgs./crnz; a flexural yield strength of at least 500 kg./cmz; a flexural modulus of elasticity of at least 15,000 to about 50,000 kgs./cmz; and a Rockwell R hardness of at least 75. Compositions made in accordance with the present invention are characterized by the use of a particular kind of monoethylenically unsaturated acrylic mono- mer alone or in combination with other compatible 4,260,701 3 monoethylenically unsaturated monomers, as the mono- ethylenically unsaturated component of the liquid resin binder. One monomer, which is essential, is methoxy- ethyl methacrylate. It preferably furnishes the major amount of the monoethylenically unsaturated monomer present, but it may be mixed with other compatible monoethylenically unsaturated monomer(s) that are suitable, such as, for example, tetrahydrofurfuryl acry- late and/or methacrylate. The other monomer, if used, is one that can copolymerize with the first monomer and that will modify the properties of the cured mono- mer mixture and/or effect cross-linking. The preferred polyfunctional monomers are selected from the group consisting of ethylene glycol dimethac- rylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacry- late, trispropylene glycol dimethacrylate, and mixtures thereof. Of these, tris-propylene glycol dimethacrylate and diethylene glycol dimethacrylate are ordinarily most preferred.’ Unfortunately, tris-propylene glycol dimethacrylate is not readily available, so that diethyl- ene glycol dimethacrylate is the polyfunctional mono- mer most commonly used in the formulations described herein. While its use tends to impart stiffness, overall strength at a given concentration is increased. These monomers impart flexural strength to the cured coat- mgs. Among the other polyfunctional monomers herein contemplated are 2,2 bis[4'-(3”-methacryloyl-2'5 hydroxypropoxy)phenyl] propane (bis GMA); tetraeth- ylene glycol dimethacrylate; 2,2 bis (4'-methacryloyl phenyl) propane; bis(2-methacryloylethyl) o-, m-, and p-phthalates; 2-acryloylethylmethacrylate, and methac- rylate terminated urethanes. Other similar polyfunctional monomers having at least two groups or moieties such as allyl, acryloyl, methacryloyl or other similar unsaturations, capable of polymerizing in the presence of the initiators and accel- erators of the present invention, are herein contem- plated. Typically, these monomers are not only mono- polymerizable and copolymerizable, but they are suit- able cross-linking agents for the monofunctional mono- mers specified above. Certain mixtures of these polyfunctional monomers may also be used if desired. For example, a mixture of allyl methacrylate and 2,2 bis[4’(-3”-methacryloyl-2”- hydroxypropoxy)phenyl] propane (bis GMA) with a mixture of diethylene glycol and triethylene glycol dimethacrylates is useful. Similarly, a mixture of diallyl phthalate and diethylene glycol dimethacrylate is use- ful. The essential monofunctional monomer, methoxy- ethyl methacrylate, or a mixture thereof with a minor amount of another compatible, suitable diluent mono- mer, is characterized by its ability to polymerize to form polymers of a substantial hardness but, surprisingly, superior flexibility, whether polymerized alone or in combination with polyfunctional monomer. The pre- ferred “essential” monofunctional monomer is me- thoxyethyl methacrylate alone. Generally the monofunctional monomer component of the binder is provided in major part or in its entirety by methoxyethyl methacrylate. Any dermatologically acceptable acrylate or methacrylate monomer may be used as a diluent for the methoxyethyl methacrylate, provided the resulting properties of the cured coating composition are acceptable. Among the diluents that have been used are tetrahydrofurfuryl methacrylate and l0 15 20 25 30 35 40 45 50 55 60 65 4 acetol methacrylate. In addition, many of the family of alkoxy alkyl methacrylates are useful diluents, espe- cially the lower alkoxy, lower alkyl methacrylates. Any dermatologically acceptable monomer known to have fairly brittle properties after curing would serve to strengthen a formulation based on methoxyethyl meth- acrylate. Conversely, the methoxyethyl methacrylate can be regarded as serving to modify the brittle proper- ties of any other monomer that. might be selected as a diluent. Generally, the polyfunctional monomer should pro- vide up to about 20% by weight of the total resin pres- ent, and the essential monofunctional monomer forms the balance. Although no polyfunctional monomer need be present in the liquid resin binder, it is preferred that it comprise at least 5% of the resin binder. The resin binder is defined as the curable monomer(s) present. The curing systems generally are those recognized in the art, and may be used in art-recognized amounts. The preferred initiators or catalysts are the free radical cata- lysts, particularly the organic peroxides. Of these, ben- zoyl peroxide and lauroyl peroxide are preferred. Ben- zoyl peroxide is the preferred initiator, and it is usually employed at a concentration of about 0.2% to about 4% by weight of the resin binder. The accelerators preferably are tertiary amines, espe- cially N,N-di(lower)alkyl-p-toluidines (e.g., N,N- dimethyl-p-toluidine, N,N-diethyl-p-toluidine) and N,N-di (lower) alkyl anilines, such as N,N-dimethyl aniline. The preferred accelerator is N,N-dihydroxy- ethyl-p-toluidine, and it is usually employed at a con- centration of about 0.1% to about 8% by weight of the resin binder. Of course, other conventional, compatible free-radi- cal catalysts and promoters, while not at present pre- ferred, may be used in lieu of or in conjunction with the foregoing. A polymeric filler material is generally incorporated in the formulation, in finely divided form. It may be soluble or partially insoluble in the coating composition. The composition is usually packaged in two portions that are mixed for use. These may be," for example, a liquid and a powder, or a paste and a paste. The particu- late polymeric filler may be packaged with either com- ponent or may be divided between the two. The pre- ferred polymeric filler materials include the copolymers of methyl and ethyl methacrylates; and the polymers and copolymers generally of the lower alkyl acrylates and methacrylates, with the lower alkyl methycrylate esters being preferred. The polymeric filler is generally present in an amount in the range from about 5% to about 75% by weight of the coating composition; more or less of any particular filler may be used, depending on the properties desired. Other components that ordinarily will be used in- clude minor amounts of such materials as dyes, opaqu- ing agents such as titanium dioxide, and stabilizers such as 3-butyl-4-hydroxy toluene. A U.V. absorber could be included but is not necessary. In a preferred embodiment of the invention, the coat- ing composition is packaged as a liquid and a powder. These are mixed together to form a coating composition at the time of use. Ordinarily, with this two package system, the catalyst is packaged separately from the monomer system. The accelerator may be with the monomer system or in the package with the catalyst (separate from the monomer). The proportions in which the two packages are blended together may be selected 4, 260,70 1 5 at a convenient level, which generally will be in the range from about 3 to 1 to about 1 to 3, and preferably, about 1 liquid to 2 powder, by weight. Coating compositions prepared in accordance with the present invention should, for consumer acceptance, convenience, and other practical reasons, set within about 120 seconds to about 400 seconds. The setting time may be adjustedvby-regulating the concentrations of the catalyst and accelerator respectively. Often only the proportion of accelerator need be increased, to ob- tain a faster setting time. In addition to the essential and preferred components of the coating composit_ions of this invention described above, other ingredients may also_be used, such as an inorganic filler material. This could be, for example, finely divided alumina, silica, quartz, glass, aluminum silicate, or the like, which are all useful in adjusting the consistency of the coating composition and for improv- ing its physical and mechanical properties. The invention will now be further described in the following specific examples in which several demon- strations of the invention are described in some detail. All parts and percentages are by weight unless ex- pressly stated to be otherwise, and temperatures are in degrees Celsius. EXAMPLES Self-Curing Artificial Fingemails The formulations described below in Table 2 were prepared and observed for performance, including flex- ural strength and hardness. Each formulation included a liquid component, whose composition is described in Table 2, and a powder component, whose composition is described in Table 3. ' The liquid component was prepared to include mono- ethylenically unsaturated monomer, often together with ethylenically polyunsaturated monomer, and accelera- tor, stabilizer, polymeric filler, and dye concentrate. . The polymeric filler in the liquid component is prefera- bly a polymethacrylate, and it must be free from resid- ual initiator if it is to be incorporated in the liquid com- ponent along with the accelerator. Any benzoyl perox- 6 ide present in the polymethacrylate is conveniently removed by baking the polymethacrylate filler prior to use. The liquid component is conveniently prepared by 5 heating the monomer(s) with- constant stirring to 40° C. to 45° C. (35° C. was used for Exs. 13-16). Each other component is then added, with stirring until each’ has completely dissolved. The polymeric filler is added last, without interruption of the heating and stirring until 10 complete dissolution has been achieved. The dye concentrate used in most of the liquid com- ponents is conveniently prepared in somewhat similar fashion, to facilitate blending. It generally has a mono- mer component, and contains accelerator, stabilizer, 15 and one or more dyes. The monomer component is heated to 40° C. to 45° C., with stirring, and the other ingredients are then added (in the order listed below). Stirring and heating are continued until dissolution is complete. 20 In the following examples, three different dye con- centrate formulations were used, described below in Table 1; TABLE 1 25 Dye Concentrates Ingredients #1 #2 #3 Methoxy Ethyl Methacrylate 100 90 90 Diethyleneglycoldimethacrylate 0 10 10 N,N-dihydroxyethyl-p-toluidine 2.0 2.0 0 Butylated I-Iydroxy Toluene 0.06 0.06 0.06 30 D&C Red #17 0.16 0.16 0.1 D&C Red #37 0.16 0.16 0 D&C Violet #2 0 0 0.04 The dyes are present for cosmetic purposes, and play 35 no material role in the physical properties of the artific- ial fmgernail material. In each example, the liquid and powder components were mixed in the proportion of 1 to 2 by weight, re- spectively, then cured for 24 hours at room temperature 40 before testing. Setting times are reported where they were observed. TABLE 2 Liquid Components, Parts by Weight Methoxyethyl ‘ _ Methacrylate and other mono- ethylenically N,N bis (2- 3-butyl-4- Dye Concen- unsaturated Polyfunctional hydroxyethyl) Poly (methyl hydroxy— centrate, Powder Example monomer T carboxylate p-toluidine methacrylate) toluene N0. + pph“ Component 1 100 — 2.5 4.5 0.06 1-0.4 A 2 90 10-DEGDMA . 2.5 4.5 0.06 2-0.4 A 3 90 10-BIS/GMA 3.2 4.0 0.06 0.1 dye’" A 4 100 _ — 2.5 4.5 0.06 1-0.4 B ' 5 90 10-DEGDMA 2.5 4.5 0.06 2-0.4 B 6 100 — 2.5 4.5 0.06 1-0.4 C 7 90 . 10-DEGDMA 2.5 4.5 0.06 2-0.4 C 8 90 10-DEGDMA 4.0 4.5 0.06 3-0.6 D 9 90 10-DEGDMA 3.2 4.5 0.06 3-0.6 E 10 100 —- 2 — 0.06 — F 11 V90 10-DEGDMA 2 —— 0.06 — F 12 80 20-DEGDMA 2 —— 0.06 — F 13 — 10-DEGDMA 2.5 4.5 0.06 — B 9o'r V 14 30 10-DEGDMA 2.5 4.5 0.06 — B 60T 15 60 10-DEGDMA 2.5 4.5 0.06 -— B ‘ 30T 16 90 10-DEGDMA 2.5 4.5 0.06 — B 17 90 10-DEGDMA 3.0 6.0 0.06 — B 7 4,260,701 TABLE 2-continued , ' _________.___Z._______________.________.___________.___ 13 90 10-BIS/GMA 3.0 6.0 0 06 B - . “pph: parts per hundred of the liquid. "‘0.06 D&C Red #17 and 0.06 D&C #37; mixed directly into the liquid. Physical Properties’ T: Tetrahydrofurfuryl methacrylate Flexural Rockwell “R" Set Time. Example Strength E3 Hardness Seconds ____._.__._._.____.._______.._.__.____M_._________.. 1 370 2 15,566 55 250-330 2 352 2 29,502 3 766 2 27,293 4 306 2 11,632 5 724 2 23,596 6 119 3 7,355 7 534 2 25,330 g _ _ 9 _ _ 10 332 2 12,100 11 630 1 21,432 12 766 1 25,786 13 796 1 35,375 14 1313 1 » 49,337 15 743 1 32,174 16 753 2 25,563 17 — — 13 — — 94 270 - 89 209 44 _.. 76 -- 16 — 82 — — . 220 at 21° C. 150 at 25° C. — 215 66 — 92 -- 100 — ‘Each value reported is average from values observed on several specimens. 1 Modulus of Rupture; approximate values. 2 Yield strength. 3 Test terminated before yield or rupture was obtained. Glossary Flexural Strength (Modulus of Rupture): Yield Strength: Flexural Modulus: Rockwell Hardness: units, kg/cmz; formula used, S = 3WL 21x12; Where S is the stress in the outer (theoretical) fiber of the specimen at midspan, in Kg/cmz; W is the load applied at the point of structural failure in Kg.; L is the span in cm.; b is the width of cm., and d is the thickness in cm. derived from the same curve as flexural strength (modulus of rupture), but at a different point, i.e., a different mode of failure. L3w in Kg. 4bd3y cmz where L, W, b, and d are as above, and y is the maximum vertical deflection of the beam, in cm. specimens for flexural strength and flexural modulus; E3: L = 2.54 cm. b = 1 cm. d = 0.2 cm. evaluated on an Instron instrument. specimen, 2 mm X 25 mm diam. DEGDMA diethylene glycol dimethacrylate - TABLE 3 Powder Compositions Parts by Weight B C D E Component A 30/70 copolymer of methyl and ethyl methacrylates (a) impregnated with 2.6% by weight benzoyl peroxide 75 70.5 — 50 (b) not impregnated 25 23.5 -— 50 copolymer powder‘ (flexibilizer) — 6 6 - titanium dioxide (opaquing agent) 0.05 0.05 0.05 0.1 polymethyl methacrylate, impregnated with 2.6% 50 50 0.05 TABLE 3-continued Powder Compositions Parts by Weight F Component A B C D E F _j.. by weight benzoyl peroxide —— — 94 — — 100 . ‘A commercially available. particulate block copolymer of methyl methacrylate, sytrene. and butadiene, in a 1:l:l monomer ratio. ' 55 60 Example 2 compared favorably in strength with a currently commercially available formulation, and ex- hibited superior flexibility. Generally the setting times for Examples 1 through 7 were considered somewhat slow for use in artificial fingernail compositions, indicating the need for higher 65 4,260,701 9 levels of catalyst and initiator for this particular applica- tion. Example 8 was prepared to have a more accept- able set time for fingernail application, and it did. The values reported are satisfactory. The color and opacity of Example 8 cured coatings were also acceptable. 5 Example 9 was prepared with a view toward balanc- ing the proportions of the respective components so as to obtain acceptable properties and costs for artificial fingernail use. As is clear from the examples, the physical properties 10 observed with Examples 1 through 7 (which have poly- 10 be used to thicken the liquid part include: ethylhydrox- yethyl cellulose; vinyl toluene/alpha methyl styrene copolymer; polyvinyl acetate; methacrylate-butadiene- styrene copolymer; and ethyl cellulose. Generally these materials may be used in the same proportions as other polymeric fillers in the liquid part, i.e., about 4 parts to about 10 parts by weight per 100 parts of total mono- mer. The invention is further demonstrated by the follow- ing examples in Table ,5, in which Ex. 19 is presented for comparative purposes. TABLE 5 __:. ' Liquid Component v Example No. 19 20 21 22 23 24 Methoxyethyl methacrylate -— 90 pbw 90 pbw 95 pbw 90 pbw 90 pbw Diethyleneglycol dimethacrylate 100 pbw 10 Triethyleneglycol dimethacrylate —— — —— — 10 - Polyethyleneglycol dimethacrylate —— — —— -— — 10 Bisphenol A diglycidyl dimethacrylate — — 10 — — — Bisphenol A Dimethacrylate 0.06 0.06 0.06 0.06 0.06 0.06 Butylated hydroxy toluene N,N-dihydroxyethyl-p-toluidine 2.5 3.0 3.0 2.5 2.5 2.5 Polymethyl methacrylate, baked — 6.0 6.0 6.0 6.0 6.0 Ethyl cellulose 4.5 — —— — — —— Powder component‘ G - H H H H H Flexural Properties Proportional Limit (Kg/cmz) 314 542 458 433 612 537 Modulus of Elasticity (Kg/cmz) 44396 41020 44834 38722 37360 31566 Modulus of Rupture (Kg/cmz) 1195‘ 1089’ 1147‘ -— 1003‘ 974* Yield Strength (Kg/cm ) 1195‘ 1089' 1147‘ 909 1003‘ 974‘ T—:..—:: See TABLE 6 below for the compositions of powders G and H. ‘The test was terminated before rupture or yield was obtained. meric filler) indicate products that are well suited for the intended use. Example 13 describes a prior art composition; it is The powder formulations used had the compositions indicated in Table 6 below. TABLE 6 within the teachings of U.S. Pat. No. 4,104,333 and is 35 -———j———————-—-—-—-———— generally similar to the compositions of Exs. VII and VIII of that patent. The physical properties of cured test specimens prepared according to Exs. 13-16 were further evaluated and are reported below in Table 4. - The results indicate no impediment to the preparation 40 of formulations where a minor proportion of the mono- ethylenically unsaturated monomer is tetrahydrofurfu- ryl methacrylate. TABLE 4 Powder Composition, PBW G H copolymer of methyl and ethyl meth- acrylates: (a) impregnated with 2.5% benzoyl peroxide 25 50 (b) not impregnated but containing about 0.6% benzoyl peroxide 75 50 Mechanical Properties, Exs. 13-16 Yield Elastic Diametral Rock- Storage Strength Modulus Compressive well “F” conditions Yield _ 3WL L3,“ Yield Hard- Example 24 hrs at Point S - 2bd2 E3 = 4b,_-13 Point HESS _jj 13 R.T. 4.2 Kg 796 Kg/cml 35375 Kg/cml — 37° C./H20 3.7 804 27274 136 Kg 14 R.'I‘. 6.2 1313 49337 . — 37° C./H20 2.2 620 25562 159 R.'I‘. 3.6 743 32174 — 37° C./H20 2.0 536 21795 143 R.T. 3.5 753 25563 — 37° C./H20 1.8 454 16140 120 56 50 39 24 The materials stored at room temperature (R.T.) out of water were much stiffer than those stored in water at 37° C. Since most artificial nails would be subjected to 60 room temperature ambient conditions (dry), the physi- cals observed under these conditions are probably more significant than the others. The liquid portion formulations of Exs. 17 and 18 can be evaluated with any of the powder mixes described in 65 Table 3, or with others. The relatively high content of polymeric filler goes into solution in the monomer, and thickens the liquid somewhat. Other materials that can Each liquid portion was prepared by dissolving, or attempting to dissolve, the solid materials in the mildly heated liquid mixture with constant stirring. The pow- ders were prepared by weighing the appropriate amounts of powder into a jar, capping, and shaking for about 178 hour. The flexural samples were prepared by mixing 1 g. liquid with 2 g. powder and casting flexural molds in a standard fashion, employed throughout all tests reported therein. The specimens were allowed to 4,260,701 11 cure at room temperature for approximately 24 hours. Flexural tests were then performed according to a stan- dard test method. The liquid/powder mix of Ex. 19 was somewhat dry, and the resulting material was somewhat opaque, indi- cating a degree of insolubility of the polymeric powder in the liquid. The polymerized material was stronger and stiffer than most of the other materials tested. Except for Ex. 22, all of the materials tested seemed a little too stiff. This may be caused by the polymeric filler. The mixtures were useful coating compositions, however. . Still further demonstrations of the invention are re- ported in Table 7 below. The procedures described above were followed in carrying out these demonstra- tions. 10 15 12 bisphenol A dimethacrylate contributed to increasing brittleness. The formulations of Examples 31 and 32 had good ‘flexural properties, and the elastic moduli and yield strengths were of interest, especially because no crosslinking resin was used. In the following demonstrations of the invention reported in Table 8, the effects of different polymeric fillers in the liquid portion were investigated, following the preparatory procedures already described. The polymeric fillers examined were methacrylatea- crylonitrile-butadiene-styrene copolymer (M-A-B-S), acrylonitrile-butadiene-styrene copolymer (A-B-S), poly (butyl) methacrylate, butyl/isobutyl methacrylate copolymer, poly (ethyl) methacrylate, styrene/methyl methacrylate copolymer, and methyl/ethyl methacry- late copolymer. Depending on the ease with which they TABLE 7 Example No. Liquid Component 25 26 27 28 29 30 31 32 Methoxyethyl methacrylate 90 pbw 90 pbw 90 pbw 80 pbw 90 pbw 90 pbw 100 pbw 100 pbw Diethyleneglycol dimethacrylate 10 10 — — 10 10 — — Bis-phenol A dimethacrylate — — 10 20 — — — -- Butylated hydroxy toluene 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Polymethyl methacrylate, baked 5.0 7.0 5.0 5.0 8.0 9.0 15.0 10.0 Powder H H H H H H H H Set time (seconds @ 23.5’ C.) 220 240 200 160 220 220 250 290 Flexural Propgrties Proportional limit (Kg/cmz) 613 528 484 730 450 502 352 344 Modulus of elasticity (Kg/cmz) 33288 29040 31168 33360 33441 29805 26000 24370 Modulus of rupture (Kg/cmz) _ _ — 1126 — —— — — Yield Strength (Kg/cmz) 1089 960 1068 — 1068 996 749 746 In Examples 25 through 32 as reported above in Table 7, flexural properties and set times were evalu- ated for methoxyethyl methacrylate formulations con- taining 10% diethyleneglycol dimethacrylate as cross- linker and 5—9% polymethyl methacrylate as filler, and 10-20% bisphenol A dimethacrylate as cross-linker and 5% polymethyl methacrylate as filler. Also evaluated were non-crosslinked formulations containing 10% and 15% polymethyl methacrylate as filler. Table 7 sum- marizes the formulations and their respective observed properties. It is difficult to draw conclusions from the formula- tions of these examples because the results of flexural tests can vary plus or minus 10%. Considering such variations, many of the formulations tested appear to have essentially the same flexural properties. The only trend apparently established was for the formulations of 35 45 dissolved, they were used at levels of 5-10 parts per hundred resin. M-A-B-S and A-B-S solutions were milky white dispersions. The poly (butyl) methacrylate appeared to swell up rather than dissolve; this could have been caused because the polymer was in the form of unpulverizable beads rather than a fine powder. All the other polymer powders dissolve fairly readily. Flexural samples were prepared as described earlier with 1 g of the liquid formulation mixed with 2 g. of powder. The flexural samples were allowed to cure at room temperature for 18-24 hours and were tested on the Instron according to a standard test method. Table 8 summarizes the formulations and respective properties. The formulation of Example 37 showed a very high proportional limit, and also a high elastic modulus. The formulation of Example 38 was interest- ing had a fairly high proportional limit with a more Examples 27 and 28, where increasing concentraitons of 50 flexible elastic modulus. Liquid Portion 33 Methoxyethyl methacrylate Diethyleneglycol dimethacrylate Butylated hydroxy toluene .06 N,N-dihydroxyethyl-p—toluidine 2.5 M-A-B-S copolymer] 5.0 A-B-S copolymerz Poly (isobutyl/butyl) methacrylate3 Poly (ethyl) mcthacryla!e3 Poly (methyl) methacrylate, baked Poly (methyl/ethyl) methacrylate4 Styrene/methyl methacrylate copolymer5 Flexural Properties TABLE 8 V Example No. 34 35 36 37 38 39 40 100 pbw 90 pbw 100 pbw 90 pbw_ 90 pbw_ 95 pbw 90 pbw 90 pbw 10 — 10 10 5 10 10 .06 .06 .06 ‘ .06 .06 0.06 0.06 2.5 2.5 2.5 2.5 2.5 2.5 2.5 — 5.0 -— — — — - 8.0 —- — — — —- — —- —— 8.0 10.0 — — — — -— - — 10.0 — — - — - — -— — 10.0 __ __ _ _ _ 3 _ 514 308 484 520 470 480 446 Proportional limit (Kg/cml) 31 Modulus of elasticity (Kg/cmz) 20365 8 32624 23347 28962 32030 29726 33170 32158 4,260,701 13 TABLE 8—continued _j__: Example No. Liquid Portion 33 34 35 Yield strength (Kg/cmz) 642 1010 698 ’methacrylate-ucrylonitrile-butadiene-styrene copolymer; Borg-Warner lacrylonitrile-butadiene-styrene copolymer; Borg-Wamer -‘Aldrich Chemical Co. ‘lbaked 30/70 methyl/ethyl methacrylate copolymer: Esschem 5Esschem A different powder component was employed in the demonstrations of the invention reported in Table 9 below. The liquid formulation of Example 38 was com- bined with polyethyl methacrylate as the powder com- ponent, in Example 42. Powder component I was prepared by pulverizing 0.64 g. of benzoyl peroxide (BPO) with 42 g. polyethyl methacrylate, sifting the material through a nylon mesh, and then mixing thoroughly by shaking in a closed container. The resultant powder contained 1.5% BPO. Flexural properties of some liquid/powder mixtures, using powder I, and prepared in the usual 1:2 propor- tions, are summarized in Table 9. Powder I imparted generally weaker properties than powdered polyme- thyl/ethyl methacrylate containing about 1.5% BPO. The “Special Adduct” employed in Examples 43 and 44 as a cross-linker is an adduct of hydroxypropyl meth- acrylate and trismethylhexamethylene diisocyanate. It is a viscous liquid and is a poor solvent for the poly- meric filler, indicating the desirability of incorporating a diluent dimethacrylate in such formulations. In addition to hydroxypropyl methacrylate, other hydroxyalkyl methacrylates may be employed to form similarly useful adducts. The hydroxy-lower-alkyl methacrylates are preferred. Also, many different diiso- cyanates may be used in making useful adducts. Gener- aly those with aliphatic backbones are preferred. TABLE 9 36 934 15 20 25 30 35 E4 37 1032 38 905 39 1080 40 976 to generate a high heat of polymerization, they should be used sparingly if at all. CONCLUSION After curing, coating compositions prepared in ac- cordance with the invention can be formulated to have, particularly when formulated according to the pre- ferred embodiments exemplified by Examples 2, 3, 5, 7, 8 and 9, respectively, a flexural modulus of rupture of at least 500 kg./cmz; a flexural yield strength of at least 500 kg./cm2; a flexural modulus of elasticity of l5,000—50,000 kg./cmz; and a Rockwell R hardness of at least 75 up to about 100. In addition, they should produce, if properly formulated to do so, an in vivo adhesion to natural human ‘nails of at least about 90 psi 6.3 kg/cmz), preferably about 100 psi 7.0 kg/cmz), with maximum values generally in the range from about 150 psi to about 200 psi (10.5 to 14.0 kg/cm2). When an inorganic filler is incorporated in a formula- tion, ordinarily it will be used in an amount in the range from about 2% to about 10% by weight of the overall composition. Such a filler should have an average parti- cle size of not more than about 60 microns in diameter, the term diameter referring to the largest dimension of the particle as is conventional. While the invention has been disclosed herein by reference to the details of preferred embodiments Example No. Liquid Component 41A 41 B 42A 42B methoxyethyl methacrylate 90 90 95 95 diethyleneglycol dimeth- acrylate 10 10 5 5 Special Adduct* —— —- — — butylated hydroxytoluene 0.06 0.06 0.06 0.06 N,N-bis dihydroxyethyl- p-toluidine 2.5 2.5 2.5 2.5 polymethyl methacrylate, baked — — l0 ‘l0 polyethyl methacrylate l0 l0 — — Powder H I H I Flexural Properties proportional limit (Kg/cmz) 520 442 470 427 elastic modulus (Kg/cmz) 32,030 27,764 29,726 24,440 yield strength (Kg/cmz) 1,032 863 905 303 modulus of rupture (Kg/cmz) 43 44 80 90 20 l0 0.06 0.06 2.5 2.5 10 10 H H 51 l 454 33,793 29,158 ——- 890 987 — ’N.N'-Bis(3-methacryloxymelhylethoxycarboxy)-trime!hy|~hexane-1,6-diamine; representative nomen- clature. Instead of one of those polyunsaturated monomers indicated in the examples, any one of the following may be used, with suitable formulating adjustments to obtain desired properties: a polyethylene glyol dimethacrylate; triethylene glycol dimethacrylate; a mixture of (1), a blend of alyl methacrylate and bis/GMA, and (2) blend of diethylene glycol and triethylene glycol dimethacry- lates; or a mixture of diallyl phthalate and diethylene glycol dimethacrylate. Since triethylene glycol dimeth- acrylate and polyethylene glycol dimethacrylate tend 60 65 thereof, it is to be understood that such disclosure is intended in an illustrative rather than in a limiting sense, and it is contemplated that various modifications in the compositions of the invention will readily occur to those skilled in the art, within the spirit of the invention and the scope of the appended claims. What is claimed is: 1. A composition suitable to be applied to a fingernail as a hardenable coating or to form an artificial nail, having an acrylic binder, a peroxide catalyst and t-’ amine accelerator curing system, and containing poly- 4,260,701 15 meric filler that is at least partially soluble in the compo- sition, the composition being formulated and the cata- lyst and the accelerator being present in a quantity to cause self-curing to occur in situ within about 400 sec- onds after mixture of the ingredients and application to 5 a nail, under ambient conditions to which the nail is normally exposed, wherein the acrylic binder consists of a mixture of the following ingredients, by weight based on the weight of the acrylic binder: (a) a first monomer component consisting of from about 0% to about 20% of a polymerizable, ethyl- enically unsaturated monomer that can form a cross-linked polymer upon polymerization during curing of the composition, which monomer con- tains in its molecule at least two groups that are capable of addition polymerization upon contact with a peroxide-type free radical initiator and a tertiary amine~type accelerator, the polymerizable groups being members of the group consisting of allyl, acryloyl, methacryloyl, and combinations 20 thereof, and (b) a second monomer component consisting of mon- omer that is monoethylenically unsaturated, in an amount up to about 100%, that copolymerizes with the first monomer component upon self-curing of 25 the composition to form a copolymeric structure that is cross-linked, the second monomer compris- ing at least a major proportion of methoxyethyl methacrylate. 2. A composition in accordance with claim 1 wherein the (a) monomer is diethylene glycol dimethacrylate. 3. A composition in accordance with claim 1 wherein the (a) monomer is a polyethylene glycol dimethacry- late. ~ 4. A composition in accordance with claim 1 wherein 35 the (a) monomer is triethylene glycol dimethacrylate. 5. A composition in accordance with claim 1 wherein the (a) monomer is 2,2 bis [4-’(3"-methacryloy1-2”- hydroxypropoxy)phenyl]propane. . 6. A composition in accordance with claim 1 wherein the (a) monomer is an adduct of a hydroxyalkyl methac- rylate and a diisocyanate. 7. The composition of claim 6 wherein the (a) mono- mer is an adduct of hydroxypropyl methacrylate and trismethylhexamethylene diisocyanate. 8. The composition of claim 1, 2, 3, 4, 5, 6 or 7 wherein the second monomer consists essentially of methoxyethyl methacrylate. 9. The composition of claim 1 wherein the acrylic binder consists essentially of methoxyethyl methacry- 50 late. 10. A composition according to claim 1, 2 or 5 that after curing exhibits a flexural modulus of rupture of at least 500 kgs./cmz; a flexural yield strength of at least 500 kg./cmz; a flexural modulus of elasticity of 55 l5,000—50,000 kg./cmz; and a Rockwell R hardness of at least 75. . 11. A self-curing composition to be applied to a natu- ral nail as a hardenable coating or to form'an artificial nail, having an acrylic binder, a peroxide catalyst and t-amine accelerator curing system, and containing poly- mer filler that is at least partially soluble in the composi- tion, the composition being formulated and the catalyst and the accelerator being present in a quantity to cause self-curing to occur in situ within about 120 to about 400 65 seconds after mixture of the ingredients and application 10 15 30 45 60 16 to a nail, under ambient conditions to which the nail is normally exposed, wherein the acrylic binder consists essentially of a mixture of the following ingredients, by weight based on the weight of the acrylic binder: (a) from about 0% to about 20% of a cross-linkable monomer selected from the group consisting of bisphenol A diglycidyl dimethacrylate (BIS/- GMA), bisphenol A dimethacrylate, an adduct of a hydroxyalkyl methacrylate and a diisocyanate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and mixtures thereof, that are capable of being polymerized upon contact with a peroxide-type free radical initiator and a t—amine-atype peroxide-type free radical initiator and a t-amine-type accelerator; and (b) from about 80% to 100% of a monoethylenically unsaturated monomer comprising at least a major proportion of methoxyethyl methacrylate. 12. The composition of claim 11 where the cross-link- able monomer is diethylene glycol dimethacrylate. 13. The composition of claim 12 wherein the mono- ethylenically unsaturated monomer consists essentially of methoxyethyl methacrylate. . 14. The composition of claim 11 wherein the (a) mon- omer is a poly(all