COMPOSITION AND PROCESS

"COATING COMPOSITION"

The present invention relates to a composition that can be used as mold release agent and to a method for applying a thin continuous film of the release agent in a mold.

In commercial operations, the mold release agent, generally a polymer or combination of polymers, can be an emulsion or a dispersion in a solvent. If dispersed in a solvent, the solvent is used as a carrier to wet the surface of a mold amplitude shape, wherein the release agent is applied. However, silicone resins, which are normally used as release agents, normally not coat well surfaces when dispersed in a hydrocarbon solvent typical. Silicone resins or ajuntam agglomerate in the surface to which are applied, thereby preventing a thin continuous film is obtained.

Therefore, there is a need ever larger develop a new release agent which may produce a thin continuous film coating on the surface of a mold.

A composition comprising a solvent; a resin, a gum, or a silicone fluid; and optionally a catalyst, a cosolvent, or both, wherein the solvent is a volatile siloxane.

There is also provided a process for applying a thin continuous film coating on or in a mold, which comprises the combination of a solvent, a silicone resin, silicone gum or silicone fluid, and optionally a catalyst, a cosolvent, or both, to produce a mold release composition; applying the mold release composition on or in a mold, and optionally curing the composition wherein the solvent is a volatile siloxane.

According to the invention, the term "mold" means one or more surfaces determinadoras shape. Any volatile siloxane may be used as a solvent of the composition of the invention. The term "volatile siloxane" refers to a siloxane that evaporates quickly under the temperature and pressure of use. Typically, it may have an evaporation rate of > 0.01 relative to n-butyl acetate, having a value of 1 assigned.

A proper solvent can have the formula of R (the R2SiO Component)_X- CRS3 or (R.₂ SiO Component)_y- where each R may be the same or different and is preferably an alkyl group, an alkoxy group, a phenyl group, a phenoxy group, or combinations of two or more thereof; and has from one to about ten, preferably one to about eight carbon atoms per group. The R can also be a halogen. More preferred R is a methyl group, and it can be replaced with a halogen, an amine, or another functional group. Subscript X can be a number of about 1 20, preferably from 1 10. Y can be a number of subscript 3 about 20, preferably from about 10 3. A preferred solvent has a molecular weight of between about 50 and about 1,000 and a boiling point of less than about 300 °c, preferably less than 250 °c, more preferably of less than 200 °c, and still more preferably less than 150 °c.

Examples of suitable include alkylmethylsiloxanes, but without being limited to them, hexamethyldisilozane, hexamethylcyclotrisiloxane, 2.5 it dichloro-1, 1, 3, 3, 5, 5, it hexamethyl Trisiloxane, 1.3-dimethyl tetramethoxy tetramethyldisiloxane, 1, 1, 1, 3, 5, 5, 5, it heptamethyl Trisiloxane, 3 - trimethylsiloxane (heptafluoropropil), octamethyl Trisiloxane, octamethyl tetrasiloxane, octamethyl cyclotetrasiloxane, decamethyl tetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane dodecamethyl pentasiloxane ℮, ℮ combinations of two or more thereof.

Any resin, gum or silicone fluid which is compatible with a volatile siloxane indicated above may be used. In general, is a polyorganosiloxane. For example, polyalkylsiloxanes terminated methoxy and the hydroxy-terminated polydimethylsiloxane can be used. The resin, gum or the silicone fluid proper may be a resin, a gum or a fluid. Examples of suitable polyorganosiloxanes include polydimethylsiloxanes, polymethyl hidrogensiloxanos, polisilsesquioxanos, politrimetil siloxanes, polydimethyl ciclosiloxanos, and combinations of two or more thereof. Each silicone resin can also contain functional groups such as halide, amine, hydroxy, epoxy, the carbinol, carboxylate, acetoxy, alkoxy, acrylate, and combinations of two or more thereof. The molecular weight can range between about 500 of about 1,000,000. A silicone resin is preferred polyorganosiloxane having terminal hydroxyl groups bonded with silicone, which is well known and is commercially available.

The siloxanes and resins, gums or silicone fluids indicated above are generally commercially available, for example, from Dow Corning Chemicals and, passage, and Michigan, and General Electric, from Fairfield, Connecticut was employed.

Any organic solvent, preferably substantially free of water as, for example, a hydrocarbon or a halogenated hydrocarbon, that is inert for other components of the composition, is compatible with the volatile siloxane and is volatile to evaporate rapidly when applied to the mold surface and may be used as cosolvent. A cosolvent can also reduce the viscosity of the composition and promote detachment of a polymer of a mold. Preferably, a cosolvent has a normal boiling point below about 300 °c, preferably below 200 °c, and more preferably below 150 °c, depending on the temperature of the mold release composition to be applied to the mold. The lower the temperature of the mold release composition to be transformed alloyed, the lower the boiling point of the solvent, and vice versa. Examples of suitable co-solvents include, but without being limited to them, the octane, decane, cyclohexane, toluene, xylene, methylene chloride, methylene dichloride, ethylene dichloride, carbon tetrachloride, chloroform, ethylene percloro, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, dioxane, white alcohol, alcohols minerals, naptha, and combinations of two or more thereof.

The mold release composition can also comprise an additional silicone compound, such as fumed silica modified, surfactants, fluoropolymers such as polytetrafluoroethylene, waxes, fatty acids such as stearic acid, fatty acid salts such as metal stearates, finely dispersed solids such as talc, emulsifiers, biocides, corrosion inhibitors.

Each component indicated above may be present in the composition in an effective amount sufficient to effectuate the proper detachment of a molded article. For example, based on the total weight of the composition, the solvent may be present in the composition in a range from about 10 about 99%; a silicone resin can be present in the composition in a range from about 0.1 about 90%. A cosolvent, if used, may be present in the composition in a range such that the sum of solvent and cosolvent is about 10 about 99%, as long as the solvent is at least about 10% present, preferably at least 20%. Other components, if present, may range from about 0.01 about 10%.

Any catalyst that can catalyze or enhance curing a composition comprising a volatile siloxane, a silicone resin and a solvent can be used herein. A preferred catalyst is a compound organic titanium. The tetraidrocarbilóxidos titanium, herein also indicated as tetraalquila of titanates, organic titanium compounds are more preferred, because they are effective and ready availability. Examples of suitable titanium compounds include those expressed by formula of Ti (RO)4, in which each R is individually selected from an alkyl radical, cycloalkyl, alkaryl, hydrocarbyl containing from about 30 1, preferably from about 18 2, and more preferably from 2 12 carbon atoms radical, and each of R may be the same or different. The tetrahidrocarbilóxidos titanium wherein the group contains 2 rboxila spinner HID and about 12 carbon atoms per radical which is a linear or branched alkyl radical are most preferred because they are relatively inexpensive, of more immediate availability, and effective in curing the composition. Titanium compounds suitable include, but without being limited to them, the tetraetóxido titanium, the titanium tetrapropóxido, the tetraisopropóxido titanium, the titanium tetrahexóxido, the tetra n-butoxide titanium, the tetra 2-ethyl hexóxido titanium, the titanium tetraoçtóxido, and combinations of two or more thereof.

Other suitable catalysts include a compound or an element group VIII of the periodic table of the elements, such as the platinum, the palladium, iron, zinc, rhodium and nickel, as well as tin compound or zirconium. Examples of suitable catalysts include, but without being limited to them, the dibutyl tin diacetate, dibutyl dilaurate, zinc acetate, zinc octoate, zirconium octoate, and combinations of two or more thereof. For example, dibutyl tin diacetate the may be used independently or in combination with a compound of titanium.

Such catalysts should be otherwise commercially available. For example, as TPT TYZOR® TYZOR® and that TBT (titanate tetra isopropyl and titanate tetra n-butyl, respectively) available from E. I. and Du Pont Company and, in Wilmington, Wilmington, USA.

Each of the catalysts listed above can be used in the composition in a range from about 10% by weight about 0.01 in relation to silicone.

The composition may be produced by any means known to one skilled in the art as, for example, mixing each component indicated above. It is preferable that the catalyst is introduced after the silicone resin, solvent and the optional cosolvent being combined.

A process for applying a thin continuous film coating on or in a mold, which comprises (1) the combination of a solvent, a silicone resin or a silicone gum or a silicone fluid, and optionally a cosolvent, a catalyst, or both, to produce a mold release composition, (2) applying the mold release composition on or in a mold, and optionally (3) curing the composition of the release. The composition release mold can be the same as the composition described above. Application of the composition release mold can be carried out by any means known to one skilled in the art as, for example, spraying, paint, rubbing, dipping, and a combination of two or more of these. Any surface of a mold amplitude shape can be applied with the release composition. Curing can be effected by any means known to one skilled in the art, such as curing at room temperature, such as from 25 °c to about 200 °c, under a pressure that accommodates the temperature range such as, for example, atmospheric pressure for about one second to about two hours. In general, the curing is carried out at a temperature and pressure wherein the molding is being executed.

To produce a molded article, a molding material or a material to be molded may be introduced on or in the mold by any means known to one skilled in the art as, for example, pumping, extrusion, mixing, or other appropriate means known to one skilled in the art. Next, a molded article is produced, which may be removed or detached from the mold by any means known to one skilled in the art. Because that the means for making a molded article are well known in the art, its description is omitted here for purposes of abstract.

The molding material may be any material that can be molded including, but without being limited to them, plastics, polymers, glass, ceramic and metals. Examples of the polymers include a resin termorrígida or a thermoplastic resin. Specific examples include the acrylonitrile-butadiene-styrene, acrylonitrile-chlorinated polyethylene-styrene, acrylic-styrene-acrylonitrile, polyacetal homopolymers and copolymers, acrylic, cellulosic, fluoropolymers, polyamides, polyacrylates, polybutylene, polycarbonates, polyesters, polyethylenes, ethylene copolymers, ethylene-acrylate ethyl, ethylene-acrylate methyl, polymethyl acrylate, polymethyl methacrylate, polybutyl methacrylate, ethylene-vinyl acetates, copolymers of ethylene and vinyl alcohol, ionomers, polymethylpentenes, polyphenylene oxides, polypropylene, ethylene-propylene copolymers, copolymers of polypropylene impact copolymer, polypropylene random copolymers, polystyrenes, styrene-acrylonitrile, styrene-butadiene copolymers, styrene-ethylene/butylene-styrene, styrene-maleic anhydride copolymers, polyvinyl chloride, polyvinylchloride (?), homopolymers and copolymers of vinylidene chloride, styrenic block copolymers, mixtures of polyolefins, elastomeric alloys, thermoplastic urethanes, polyethylene terephthalate, polybutylene terephthalate, thermoplastic copolyesters, polyethers, polyamides thermoplastic, copolymers of polyether-polyamide block, molding compounds allyl, methylene bis-maleimides, epoxy resins, phenolic resins, polyesters, ethylene-propylene-diene rubber such as EPDM, polyimides, ionomers, injection molded polyurethanes, polyurea segmented/urethanes, polyurethanes reaction, silicone, urea resins-melamine-formaldehyde, polyacetals, polyesters, polyamides, ionomers, and combinations of two or more thereof. These polymers are well known to a skilled artisan.

The following examples are illustrative of the invention and should not be construed to unduly limit the scope of the invention.

Example 1

This example demonstrates that coatings of silicone resin continuous can be made finer by using a volatile methyl siloxane instead of using petroleum ether.

A release agent composition comprising 80% solvent (petroleum ether or octamethylcyclotetrasiloxane (volatile methyl)), 20% of resins and silicone fluids, and about 0.2% of catalyst (based on the total weight of solvent and resin and the fluid; TYZOR® that TBT dibutyl tin diacetate and) was sprayed onto glass microscope slides of 1 inch by 3 inches (2.54 cm by 7.62 cm) previously heated to 65 °c with weighed the amount shown in the table below. After allowing for a sufficient time the solvent evaporating in a sleeve, the release agent was cured for two minutes at 65 °c. Slides were then re-weighed and were visually examined under a microscope to estimate the surface coverage of the blade with silicone resin. The results are shown in table 1.

The coating was very uneven and lumpy in blades coated using the petroleum ether as a solvent. The coating using the methyl siloxane as solvent was very smooth. Replacing the petroleum ether alcohols minerals worsened the agglomeration of silicone resins glass surface.

Example 2

This example serves to demonstrate how using various solvents of volatile methyl siloxane promotes the formation of continuous smooth coatings of various silicone resins, fluids and functional fluids applied to a high temperature.

Silicone resins, fluids and fluids were dispersed in various functional hydrocarbon solvents and volatile alkylmethylsiloxanes in at a concentration of 5% polymer solid weights and 95% by weight of solvent. Silicone polymers and solvent were sprayed, using an aerosol spray Preval, on glass microscope 1 "3 X-" (2.54 cm χ 7.62 cm) previously heated to 65 °c heavy. After the solvent was evaporated, slides were reweighed to determine the weight of the coating and were visually examined for smoothness and the coverage of the coating, such as shown in table 2.

¹ AS denotes the silicone polymer; the polymer is the copolymer of methyl silsesquioxane-dimethyl hydroxy-terminated; the polymer b is the copolymer of methyl silsesquioxane-dimethyl methoxy terminated; the polymer c is the hydroxy-terminated polydimethylsiloxane of 14,000 centistokes (centistoke); and the polymer d is the polydimethylsiloxane of 60,000 centistokes.

² Pe is petroleum ether; ms is alcohols minerals; s is Stoddard solvent; WHO denotes octamethylcyclotetrasiloxane; DMS is decamethyl tetrasiloxane; and OMTS is octamethyl Trisiloxane.

The results show that the silicone polymers dispersed in the VMS fluids produced continuous smooth films, whereas the same silicone polymers dispersed in hydrocarbon solvents produced incomplete rough films.

Example 3

This example demonstrates how the use of solvents of volatile methyl siloxane promotes the formation of coatings smooth continuous silicone polymers when applied at room temperature.

A sample of a silicone gum was dispersed in petroleum ether while a second sample of the same silicone gum was dispersed in fluids at a concentration of 5% VM by weight solids of the polymer and 95% by weight of solvent. The silicone polymer and solvent were sprayed, by using an aerosol spray Preval, in glass microscope 1 "X-3" (7.62 cm X-2.54 cm) previously weighed at room temperature. After the solvent was evaporated, slides were reweighed to determine the weight of the coating and were visually examined for smoothness and the coverage of the coating as shown in table 3.

¹ AS denotes the silicone polymer; the polymer d is polydimethylsiloxane of 60,000 centistokes.

² Pe is petroleum ether; WHO denotes hexamethyldisilozane and OMTS is octamethyl Trisiloxane.

The results show that the silicone polymers dispersed in the VMS fluids produced a continuous smooth film, whereas the same silicone polymers dispersed in a hydrocarbon solvent produced a rough film incomplete when applied at room temperature.

Example 4

This example serves to demonstrate how the use of a volatile methyl siloxane may promote formation of a thin smooth coating of a silicone release agent fully formulated.

Was purchased a commercial release agent for plastics, adhesives and elastomeric products. The manufacturer describes the product as having a protein content of 50% of active material comprising trimethylated silica (trimethylsiloxy) silane and tetra and the use of a mixture of hydrocarbon solvent composed Stoddard solvent, xylene and ethylbenzene. The manufacturer's insert advises the dilution of 10 parts of release agent with 80 parts of isopropanol and 10 parts of toluene to enhance wetting the surface. Following the manufacturer's recommendation, the release coating was diluted to 5% by weight solids of the polymer by utilizing a mixture of 10/80/10% by weight of release agent, isopropanol and toluene. The coating was then applied release by employing a aerosol spray Preval, in glass microscope 1 "X-3" (7.62 cm X-2.54 cm) previously heated to 65 °c heavy. After the solvent was evaporated, slides were reweighed to determine the coating weight and they were visually examined for smoothness and the coverage of the coating. As comparison, the release agent was diluted octamethyl Trisiloxane (OMTS), 5% by weight again to solids of the polymer, is applied to a glass slide by employing the manner described. Results showed that the hydrocarbon solvent produced a coating manufacturer's recommended incomplete lumpy, whereas the use of the solvent produced a continuous smooth coating VM. The results are shown in table 4, in which IPA is isopropyl alcohol.

Example 5

This example serves to demonstrate such as forming a continuous smooth coating to improve the performance of a release agent.

A release coating using a copolymer of methyl silsesquioxane-dimethyl siloxane is a polydimethylsiloxane fluid was dispersed in various solvents at a concentration of 5% by weight of solids. The coating was applied by using an aerosol spray in a mold box Preval aluminum 9 "X-12" X-3" (22.86 cm X-X-30.48 cm 7.62 cm) heated to 65 °c pre-weighed. After the solvent had evaporated, the mold was cooled to room temperature and weighed again. The mold was then heated again and filled with resin based polyurethane flexible foam of toluene diisocyanate. The mold lid was secured and the expansion foam was taken to cure for six minutes while being maintained at 65 °c in an oven. The foam was then removed from the mold by hand. If the foam was removed successfully without tearing the mold, the mold was replenished with polyurethane resin again without coat again the mold release agent. This cycle was repeated until noted a tear in the foam. The results are shown in table 5, in which the abbreviations are the same as those in table 1.

Tables

The results show that a release coating dispersed in a fluid or in a VM and VM of hydrocarbon solvent results in a significantly improved performance as compared to the use of only a hydrocarbon solvent.