US20060079600A1

US20060079600A1 - Anti-stick coating for surfaces

Info

Publication number: US20060079600A1
Application number: US11/249,203
Authority: US
Inventors: Usha Gopalratnam; Mark Gullo; Leonard Testa
Original assignee: Individual
Current assignee: EIDP Inc
Priority date: 2004-10-13
Filing date: 2005-10-13
Publication date: 2006-04-13
Also published as: WO2006044507A1; EP1809456A1; KR20070084204A

Abstract

A release agent composition to prevent sticking and facilitate separation of surfaces, such as patterns and core boxes from foundry molds and core s comprises (a) a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene; (b) a moisture-curable silicone; (c) a catalyst; and (d) a solvent. Further is provided a method to improve the release properties of molds removed from a pattern or core box comprising applying the release agent composition to the pattern or core box surface.

Description

CROSS REFERENCE(S) TO RELATED APPLICATION(S)

This application claims priority under 35 U.S.C. §119 from U.S. Provisional Application Ser. No. 60/618,519 (filed Oct. 13, 2004) which is incorporated by reference herein for all purposes as if fully set forth.

FIELD OF THE INVENTION

This invention relates to a composition that can be used to coat a substrate surface thereby improving the surface function. In particular, the composition can be used as a release agent for facilitating release of a mold from a pattern or core box. The composition can be applied generally to substrate surfaces to prevent sticking.

BACKGROUND OF THE INVENTION

Many industrial operations require the use of release agents to reduce the tendency of sticking, such as of a molded product to stick to a mold, or that of a tool, die, or machine part to stick to the workpiece.
In foundry operations, metal parts are frequently made using “sand casting” methods wherein disposable foundry shapes, such as molds and cores, are fabricated with a mixture of sand and an organic or inorganic binder, sometimes referred to as a “foundry mix”. Molds and cores are produced by chemical or heat hardening of the mixture of sand and binder onto a pattern or core box. Sometimes a catalyst is used to cure the foundry mix more rapidly. A mold release agent, generally a polymer or a combination of polymers, is used to reduce or eliminate adhesion of a mold to a pattern or core box surface.
Various processes, such as, for example, the air-set or no-bake process, the carbon dioxide process, the cold box process, hot box processes, and similar mold manufacturing processes are well-known to those skilled in the art. In these processes, sand and binder mixture is molded upon patterns or in core boxes. The patterns may be constructed from plastic, wood, or metal. Typically, metals are aluminum and cast iron. Other materials may also be used.
In the no-bake process, the sand/binder mixture, or foundry mix, contains a catalyst, so the mixture will cure rapidly without additional reagents. Heat may be added if desired in some processes to increase the cure rate. The foundry mix is shaped by compacting it in a pattern and allowing it to cure, so that the mix is self-supporting. The composition of the foundry mix, including any catalyst must be such as to allow adequate worktime to allow shaping before the mixture hardens.
In the cold box method, a volatile curing catalyst (gaseous reagent) is passed through a shaped mixture of the foundry mix, usually in a core box, as opposed to a free-standing pattern mold. In this particular method of manufacture, the foundry mix must have adequate shelf life, meaning that it will not harden in the absence of a catalyst. The cure rate must be very rapid once the foundry mix is exposed to a catalyst.
Mold release agents are typically sprayed or brushed onto a pattern or core box surface periodically during pattern or core preparation. The mold release agent can be used an emulsion or dispersion. If dispersed in a solvent, the solvent serves to wet the surface of a shape-determining mold, onto which the release agent is applied.
In the related art, silicone resins have been used as lubricants and release agents to prevent the pattern from sticking to the hardened foundry mixture. Silicones often do not, however, coat surfaces well when dispersed in a typical hydrocarbon solvent. The silicone resins are prone to bead or puddle on the surface to which they have been applied, thus preventing a thin, continuous film from being achieved.
Polytetrafluoroethylene (PTFE) dispersions are known, and can be used for treating the surfaces of various materials, such as metals, glass fibers, wood, rubber, and the like, to provide a protective, lubricating and anti-adhesive effect.
U.S. Pat. No. 6,596,829 discloses a mold release agent composition that enables numerous clean, lubricious releases of metal castings from hardened sand molds. The composition comprises a fluorotelomer comprising repeat units derived from a fluoroalkene and optionally, a comonomer having an end group derived from a secondary alcohol or derivative thereof. The composition is applied to the surface of a substrate by conventional means such as spraying, dipping, wiping, brushing, or combinations of two or more thereof, for use as a release agent or lubricant.
It is highly desirable to use the same pattern or core box many times to generate a number of molds from the same pattern or core box. Therefore, it is important for the pattern or core to be quickly and cleanly released from the finished molds with a minimum amount of release agent residue or build up on the pattern, and with minimal need to clean the pattern surface. One object of this invention is to provide an improved mold release agent composition that enables multiple release cycles, especially in cold box foundry processes. As used throughout the specification and claims, “release agent” is used to identify various composition embodiments of the invention having lubricant and abrasion resistant properties that facilitate the clean, low friction separation of a workpiece from a substrate, including patterns from cores and molds, castings from molds, cores, and dies, and workpieces from tools and machine components. A workpiece is any object that is molded, stamped, drilled, ground, or otherwise worked upon by a manual or mechanical tool, mold, die, or the like.
More generally, release agents provide protective coatings and can prevent foreign matter from sticking to surfaces. Release agents can be used to prevent soil and stains from sticking to surfaces. Release agents can also prevent food from sticking to cookware and other surfaces in a typical household. For these reasons, among others, an improved release agent is desired.

SUMMARY OF THE INVENTION

This invention is directed to a release agent composition that facilitates separation of patterns and core boxes from foundry molds and cores, and castings from molds and workpieces from dies, tools, and machinery components. The release agent also protects surfaces by preventing foreign matter from sticking to surfaces. This invention is also directed to a release agent composition that facilitates cleaning of surfaces, such as concrete, tile, and wood. The release agent comprises (a) a crosslinkable fluorotelomer comprising repeat units derived from a fluoroalkene; (b) a moisture-curable silicone; (c) a catalyst; and (d) a solvent.
This invention is also directed to a method to ease separation of a workpiece from a substrate comprising applying a composition comprising (a) a crosslinkable fluorotelomer comprising repeat units derived from a fluoroalkene; (b) a moisture-curable silicone; (c) a catalyst; and (d) a solvent to a surface of the workpiece, the substrate, or both. In one particular embodiment, the method is directed at improving the release properties of molds removed from a pattern or cores from a core box wherein the method comprises applying a composition comprising (a) a crosslinkable fluorotelomer comprising repeat units derived from a fluoroalkene; (b) a moisture-curable silicone; (c) a catalyst; and (d) a solvent to a surface of a pattern or core box.

DETAILED DESCRIPTION OF THE INVENTION

The cross-linkable fluorotelomer can be based on any fluoroalkene repeating unit that can produce a fluorotelomer having the properties disclosed herein can be used. In one embodiment, the fluoroalkene monomer contains 2 to about 10, and in another, 2 to 3, carbon atoms. Examples of suitable fluoroalkenes include, but are not limited to, 1,1-difluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene (TFE), 3,3,3-trifluoropropene, hexafluoropropylene (HFP), and combinations of two or more thereof. In a particular embodiment, the fluoroalkene is TFE.
In one embodiment, the fluorotelomers are homotelomers. In another embodiment, a cotelomer (copolymer) containing repeat units derived from a comonomer can also be produced. The comonomer is generally an ethylenically unsaturated compound, which can be fluorinated or perfluorinated. In an embodiment, the amount of repeat units derived from a comonomer can be in the range of from about 0.1 to about 10, and in another embodiment, 0.3 to 3.0 weight % of the copolymer.
Suitable comonomers include, but are not limited to, ethylene, propylene, butylene, decene, 1,1-difluoroethylene, 1,2-difluoroethylene, TFE, 3,3,3-trifluoropropene, HFP, and combinations of two or more thereof. The preferred comonomers are perfluorinated comonomers. Preferred comonomers are TFE, HFP, or combinations thereof.
The fluorotelomer is cross-linkable, meaning, a cross-link feature has been designed into its structure. One example of a cross-linkable fluorotelomer has an end group derived from a secondary alcohol or derivative thereof, as disclosed in U.S. Pat. No. 6,596,829.
A crosslinkable fluorotelomer can be prepared by a telomerization process. The process may comprises, consists essentially of, or consists of combining a fluoroalkene, and optionally, a comonomer, in a hydrofluorocarbon solvent with a free radical initiator and at least one secondary alcohol or derivative thereof.
A hydrofluorocarbon is used in a process for producing the fluorotelomer of the composition. The hydrofluorocarbon can also be incorporated into the fluorotelomer as an end group. The suitable hydrofluorocarbons include, but are not limited to, any of those disclosed in U.S. Pat. No. 5,310, 870, the disclosure of which is incorporated herein by reference. Examples of suitable hydrofluorocarbons include, but are not limited to, 2,3-dihydrodecafluoropentane, perfluorobutyl methyl ether, perfluorobutyl ethyl ether, 2,4-dihydrooctafluorobutane, 1,1,2,3,3,3-hexafluoropropyl methyl ether, 2-trifluoromethyl-2,3-dihydrononafluoropentane, 1,1,1,3,3-pentafluorobutane, or combinations thereof. These hydrofluorocarbons can be obtained commercially. For example, 2,3-dihydrodecafluoropentane is available from E. I. DuPont de Nemours and Company, Wilmington, Del. and perfluorobutyl methyl ether and perfluorobutyl ethyl ether are available from 3M Company, Minneapolis, Minn.
Essentially any free radical initiator can initiate reaction to produce the fluorotelomers in the presence of a hydrofluorocarbon, fluoroalkene, and secondary alcohol. Preferred free radical initiators are di-tertiary butyl peroxide, tertiary-butyl perbenzoate, tert-amyl peroctanoate, tert-amyl peroxy-2-ethylhexanoate, and azo initiators such as 1,1 -azobis(cyanocyclohexane) and most preferred is di-tertiary butyl peroxide. The amount of free radical initiator used preferably falls within the range of 0.4 to 3.0, more preferably 0.7 to 2.5, weight %, based on the weight of the fluoroalkene.
A majority of the end groups of the fluorotelomer may be derived from the secondary alcohol or derivative thereof. Particularly suitable secondary alcohol or derivative thereof is one that is substantially soluble in a hydrofluorocarbon disclosed herein. In one particular embodiment, the secondary alcohols used are those having at least 4 to about 12 carbon atoms and an α-hydrogen. The end group can also be derived from a derivative of a secondary alcohol. The derivative of suitable secondary alcohol can include an ether or ester of a secondary alcohol or combinations thereof. Also suitable are combinations of a secondary alcohol, an ether thereof, and/or an ester thereof. Particular examples of suitable secondary alcohols of some embodiments include, but are not limited to, 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, 2-butylacetate, cyclohexanol, 1-methoxy-2-propanol, 1-methoxy-3-butanol, 1-methoxy-2-pentanol, 1-methoxy-2-propanol acetate ester, and combinations of two or more thereof. In other embodiments, 2-butanol, 2-pentanol, or combinations thereof, are used.
The amount of secondary alcohol can be that which produces a fluorotelomer with a number average molecular weight in the range of from about 1,800 to 75,000 in one embodiment, and from about 3,000 to 30,000 in another. For example, the amount of secondary alcohol can be between about 0.1 to about 5, preferably about 0.3 and about 5, and preferably 2.5 to 4.0 mole %, based on the total number of moles of fluoroalkene.
The process can be carried out at temperatures in the range of about 100° C. to about 200° C., preferably about 110° C. to about 180° C., and more preferably 120° C. to 160° C. at autogenous pressures. The pressure can range from about 100 to about 700 psig, preferably about 400 to about 600 psig, and more preferably about 500 psig. The preferred time period is about 1-6 hours, though it can be shorter or longer than this range. In a continuous flow reactor, the reaction can proceed for about 1-2 hours. A batch process can be preferably carried out at an autogenous pressure with temperatures in the range of about 125° C. to about 160° C. for about 4-6 hours. The molar ratio of hydrofluorocarbon to fluoroalkene can be in the range of from about 1:1 to about 10:1, preferably 2:1 to 8:1. Generally the higher the ratio, the lower the telomer molecular weight.
After the telomerization process, the fluorotelomer is generally dispersed as a suspension or emulsion in the hydrofluorocarbon and is recoverable in that form by filtration or other means. The dispersion can contain from about 5-20 weight % of the fluorotelomer, with dispersions of high molecular weight fluorotelomers falling at the low end of this range. If desired, the fluorotelomers can also be dispersed in other solvents such as isopropanol or water.
The molar ratio of the repeat units derived from the fluoroalkene to the secondary alcohol or its derivative end group can be in the range of from about 18:1 to about 500:1, preferably about 120:1 to about 150:1. The molar ratio of the repeat units derived from the fluoroalkene to the hydrofluorocarbon end group can be in the range of from about 800:1 to about 2500:1, preferably about 2000:1 to about 2400:1.
Generally, a minor amount of the free radical initiator can also be incorporated into the fluorotelomer. The amount incorporated generally is about the same as, or lower than, that of the hydrofluorocarbon.
The crosslinkable fluorotelomer can have or comprise a structure depicted as either H(CX₂)_pB_qD_ror a mixture of H(CX₂)_pB_qand H(CX₂)_pD_r. In the formulae, X is H or F in which, in some embodiments, at least 80% is F. in other embodiments, at least 90% is F, and in still other embodiments, at least 99% is F; p is a number from about 36 to about 1500, preferred 60 to 600; B denotes any repeat units derived from a hydrofluorocarbon; q is a number from 0.02 to 0.4; D represents the end group derived from a secondary alcohol or its derivative; and r is a number from 0.2 to 1.0.
Crosslinkable fluorotelomers generally have enhanced bonding, compared with non-crosslinked telomers, to the surface of a substrate, which can be made of wood, metal, plastic, rubber, stone, cement, concrete, glass, fiber, tile, and combinations of two or more thereof. Crosslinking also achieves other desired properties, such as hardness, rapid curing, and non-reactivity toward the pattern or core box or other surface of a substrate, thereby reducing or eliminating residues of release agent or foundry mix on said substrate.
The term “moisture-curable silicone” refers to silicone resin, silicone gum, silicone fluid, or combinations of two or more thereof wherein the silicone is moisture curable. By “moisture curable”, it is meant that the silicone hydrolyzable terminal groups, such as, for example, alkoxy, carboxy, and amino groups. It is recognized that moisture curable silicones may comprise non-hydrolyzable terminal groups, such as hydroxy groups. However, the number of non-hydrolyzable terminal groups remains below the limit at which the silicone would no longer be moisture curable. Such silicones are known in the art and are generally available commercially, for example, from Wacker Silicones, Adrian, Mich. (a division of Wacker-Chemie GmbH, Munich, Germany), Dow Coming, Midland, Mich. and General Electric Company, Fairfield, Conn. The silicones also can be produced by any methods known to one skilled in the art. For example, the silicone can comprise fragments having the structure
—(R₃SiO_0.5)_m(R₂SiO)_n(RSiO1.5)_p(SiO₂)_q—
where each R can be the same or different and is independently selected from the group consisting of hydrogen, a hydrocarbon radical of 1-20 carbon atoms, and combinations of two or more thereof. The radicals can include alkyls, alkenyls, and aryls such as methyl, ethyl, propyl, butyl, vinyl, allyl, phenyl, and combinations of two or more thereof. The subscripts m, n, p, and q comprise the molar ratio of the units with the sum of m, n, p, and q equaling to 1. It can also be a mixture of resins. Generally, at least one of the R groups is phenyl such as, for example, -(MeSiO_3/2), (MePhSiO_2/2), (PhSiO_3/2), (Ph₂SiO_2/2)—. An example of a moisture-curable silicone is methoxy-terminated methyl phenyl silicone.
Suitable moisture-curable silicones include polyorganosiloxanes such as, for example, alkoxy-terminated polyalkylsiloxanes and amino-terminated polyalkylsiloxanes, and combinations of two or more thereof. Examples of suitable polyorganosiloxanes include, but are not limited to, polydimethylsiloxanes, polymethylhydrogensiloxanes, polysilsesquioxanes, polytrimethylsiloxanes, polydimethylcyclosiloxanes, and combinations of two or more thereof which are alkoxy-, especially, methoxy-terminated.
Each moisture-curable silicone can also contain functional groups such as halide, amine, hydroxy, epoxy, carbinol, carboxylate, acetoxy, alkoxy, acrylate, and combinations of two or more thereof. The molecular weight can be in the range of from about 500 to about 1,000,000.
Any catalyst that can catalyze or enhance the curing of a coating composition disclosed above can be used herein. Examples include, but are not limited to, zirconium or titanium or those expressed by the formula M(OR²)₄where M is zirconium or titanium and each R²is individually selected from an alkyl, cycloalkyl, alkaryl, hydrocarbon radical containing from about 1 to about 30, or from about 2 to about 18, or from about 2 to about 12 carbon atoms per radical and each R²can be the same or different. Catalysts of the formula M(OR²)₄are particularly suitable because they also function as a crosslinking agent which is compatible with the secondary alcohol or derivative thereof end groups on the crosslinkable fluorotelomer.
Specific examples of catalysts include, but are not limited to, zirconium acetate, zirconium propionate, zirconium butyrate, zirconium hexanoate, zirconium 2-ethyl hexanoate, zirconium octanoate, tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, tetrabutyl zirconate, titanium acetate, titanium propionate, titanium butyrate, titanium hexanoate, titanium 2-ethyl hexanoate, titanium octanoate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and combinations of two or more thereof. In particular embodiments, the catalyst is a crosslinking agents and is tetraisopropyl titanate, tetrabutyl titanate, or a combination thereof.
Other suitable catalysts include, without limitation, a Group VIII metal such as platinum, palladium, iron, rhodium, and nickel, or a complex thereof. Catalysts including, without limitation, zinc, tin and zirconium, and complexes thereof, are also suitable catalysts. Examples of still other suitable catalysts include, but are not limited to, dibutyltin diacetate, dibutyl dilaurate, zinc acetate, zinc octanoate, and combinations of two or more thereof. For example, dibutyltin diacetate can be used independently or in combination with a titanium compound.
Each of the catalysts disclosed above can be used in the composition in the range of from about 0.001 to about 10% relative to the total weight of the composition.
A solvent for use in the release agent composition can be or comprise aromatic hydrocarbon, alkane, alcohol, ketone, ester, ether, inorganic solvent, water, and combinations of two or more thereof such as, for example, xylene, benzene, toluene, n-heptane, octane, cyclohexane, dodecane, methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, dipropylene glycol, dipropylene glycol methyl ether, methylene chloride, methylene dichloride, ethylene dichloride, carbon tetrachloride, chloroform, perchloroethylene, ethyl acetate, tetrahydrofuran, dioxane, white spirit, mineral spirits, naphtha, and combinations of two or more thereof.
Optionally, a silicone intermediate may also be present, typically at less than 1%. For purpose of distinguishing the moisture-curable silicone from silicone intermediate, the silicon intermediate refers herein to silicones such as polyorganosiloxanes, not moisture curable, such as, for example, hydroxy-terminated polyorganosiloxane. It is recognized that non-moisture curable silicones may comprise hydrolyzable terminal groups, such as methoxy groups. However, the number of hydrolyzable terminal groups remains below the limit at which the silicone would be moisture curable. Examples of polyorganosiloxanes include, but are not limited to, polydimethylsiloxanes, polymethylhydrogensiloxanes, polysilsesquioxanes, polytrimethylsiloxanes, polydimethylcyclosiloxanes, and combinations of two or more thereof which are hydroxyl-terminated.
A silicone intermediate may also be or comprise a volatile siloxane. The term “volatile siloxane” refers to a siloxane exhibiting volatility (the property of vaporizing readily under given temperature and pressure conditions) under the temperature and pressure of use. Typically, a volatile siloxane has an evaporation rate of more than 0.01 relative to n-butyl acetate which has an assigned value of 1. A volatile siloxane can have the formula of R¹(R¹ ₂SiO)_xSiR¹ ₃or (R¹ ₂SiO)_ywhere each R¹can be the same or different and can be an alkyl group, an alkoxy group, a phenyl group, a phenoxy group, or combinations of two or more thereof, having 1 to about 10 or 1 to about 8 carbon atoms per group. R¹can also be a substituted alkyl group. For example, R¹can be a methyl group or higher alkyl and can be substituted with a halogen, an amine, or other functional group. Subscript x can be a number from about 1 to about 20 or from about 1 to about 10 and y can be a number from about 3 to about 20 or from about 3 to about 10. Such volatile siloxane can have a molecular weight in the range of from about 50 and to about 1,000 and a boiling point less than about 300° C.
The release agent can further comprise additional components such as modified fumed silica, 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. These are typically present in an amount of 0.01 to about 10 wt % of the total release agent composition.
Each component disclosed above can be present in the release agent composition of this invention in an effective amount sufficient to produce an effective release agent. The crosslinkable fluorotelomer is typically present in an amount of 0.1 to about 30 wt % of the total release agent composition. Typically, the silicone is present in an amount of about 5 to about 20 wt % of the total release agent composition.
The release agent composition can be produced by any means known to one skilled in the art such as, for example, mixing each component disclosed above.
The release agent composition of this invention has excellent release qualities. Thus, the release agent is useful in a method to ease separation of a workpiece from a substrate comprising applying a composition comprising (a) a crosslinkable fluorotelomer comprising repeat units derived from a fluoroalkene; (b) a moisture-curable silicone; (c) a catalyst; and (d) a solvent to a surface the workpiece, the substrate, or both.
The substrate, can be wood, metal, plastic, rubber, stone, cement, concrete, glass, fiber, tile, and combinations of two or more thereof. Examples of metal surface include, but are not limited to, paper rolls, drum dryer rolls, corrugator rolls, pressure rolls, conduit, hot plates, fan blades, chain links and mold plates. The term “substrate” is sometimes referred to as “article”.
Application of the composition to a substrate can be carried out by any means known to one skilled in the art such as, for example, spraying, brushing, wiping, dipping, and combinations of two or more thereof. Curing is carried out in a moisture-containing atmosphere. Curing can be carried out by any means known to one skilled in the art such as curing at ambient temperature such as from about 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 2 hours. Generally, curing is carried out at the temperature and pressure at which the molding is being carried out.
The release agent composition allows for multiple reuses of the same pattern or core box to generate a large number of molds. Thus, the release agent can be used in various mold manufacturing processes, including air-set or no-bake process, the carbon dioxide process, and the cold box process. The mold can be made from any composition useful as a foundry mix. A typical mix comprises sand and a binder, and optionally, a catalyst. Other suitable aggregate materials can be used in combination with, or in place of the sand in the foundry mix, such as for example, zircon, aluminosilicates and the like. Selection of the particular binder will generally depend on the mold manufacturing method and gaseous reagent employed, if the cold box method is used. Preferred combinations of gaseous reagent/binder are known to those skilled in the art.
The present invention provides a method to improve the release properties of molds removed from a pattern or core box comprising applying a composition comprising (a) a crosslinkable fluorotelomer comprising repeat units derived from a fluoroalkene; (b) a moisture-curable silicone; (c) a catalyst; and (d) a solvent to a surface of a pattern or core box. While the discussion of mold-forming processes below represents cold box and no bake processes, the selection of these illustrations is not intended to imply any limit to the processes to which compositions of the various embodiments of this invention are applicable. The method is especially useful with patterns and core boxes constructed of wood and molds with wood tooling. The composition does not penetrate the wood and remains on the surface to enable multiple successive use of the same pattern or core box.
In a cold box process, the method comprises (a) applying a composition comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone, a catalyst, and a solvent to the surface of the pattern or core box; (b) molding a foundry mix into the desired shape by shaping to the pattern or charging to the core box; and (c) contacting the foundry mix with a volatile curing agent. Examples of volatile curing agents would be secondary or tertiary amines or sulfur dioxide.
In a no bake process, the method comprises (a) applying a composition comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone, sufficient catalyst to enable curing, and a solvent to the surface of the pattern or core box; (b) molding a foundry mix comprising sand and a binder into the desired shape by shaping to the pattern or charging to the core box; and (c) curing the binder.
Also disclosed is a pattern or core box comprising a surface or a portion of the surface coated with a composition comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone, a catalyst, and a solvent. The substrate and composition are as disclosed above.
The release agent composition has excellent adhesion to wood surfaces. Thus, when used with molds having wooden tooling, the composition is an especially suitable mold release agent.
The release agent composition can be used in a variety of applications in addition to its use as a mold release agent.
The release agent composition has excellent adhesion to rubber. The composition may be applied to a rubber surface, such as weatherstripping, for example, around car doors and windows as a method to prevent squeaking.
The release agent composition protects surfaces by preventing foreign matter from sticking to surfaces coated with the composition. Foreign matter may comprise one or more of soil, stain, food particles, and the like. Thus, a method to prevent foreign matter from sticking to a surface of a substrate comprises treating a surface with a release agent composition of this invention and allowing to cure. In this manner, the release agent acts as a barrier or sealant. The substrate, may comprise wood, metal, plastic, rubber, stone, cement, concrete, glass, fiber, tile, and combinations of two or more thereof.
The release agent composition has excellent adhesion to polished surfaces, including metals, such as steel. There is further provided a method to reduce formation of rust on a steel surface, comprising applying a release agent composition of this invention to a steel surface. Upon exposure to a corrosive environment, such as salt water, formation of rust is reduced or may be substantially eliminated.
Also, a surface of an article or other substrate having deposited thereon a release coating composition of this invention is also contemplated herein.

EXAMPLES

A commercially available packaging tape was coated with the Example Composition described in Table 1 and its releasability from various surfaces was qualitatively compared with a 350 Centistoke silicone oil, available from Dow Coming, and a PTFE composition, DryFilm RA\IPA\5% (available from by E. I. du Pont de Nemours and Company, Wilmington, Del.). The silicone oil and PTFE composition are both commonly used release agents.

TABLE 1


Example Composition

		Amount,
Component	Supplier	lb

Sitres ® MSE 100 silicone	Wacker Silicones, Adrian, MI	0.700
resin
Dow Corning ® Z-6018	Dow Corning, Midland, MI	0.150
silicone intermediate
Dow Corning 9770 reactive	Dow Corning, Midland, MI	0.159
silicone oil
Methyl Ethyl Ketone	ExxonMobil Chemicals,	1.000
	Houston, TX
Cross-linkable	E. I. du Pont de Nemours and	0.740
polytetrafluoroethylene, 25%	Company, Wilmington, DE
in isopropanol
Tetrabutyl titanate	E. I. du Pont de Nemours and	0.100
	Company, Wilmington, DE
TM3-65A solvent blend	Chemical Solvents, Inc.,	4.106
	Cleveland, OH

Aluminum weighing pans of approximately 4″ diameter and pine wood strips of approximately 4″×1.5″ were coated with a light coat of the Example Composition, the silicone oil and the PTFE composition. The Example Composition was allowed to dry and cure for two hours. One inch wide packaging tape was pressed against each surface and immediately removed. Packaging tape was used because of its superior adhesion qualities.
The Example Composition was not removed from either surface with packaging tape, as determined by failure of the tape to adhere to the surface. The PTFE released the tape two times from the aluminum pan, and three times from the wood before the tape began to adhere. The silicone oil released the tape twice from the aluminum and one time from the wood before the tape began to adhere.

Claims

1. A release agent composition comprising (a) a crosslinkable fluorotelomer comprising repeat units derived from a fluoroalkene; (b) a moisture-curable silicone; (c) a catalyst; and (d) a solvent.

2. The composition of claim 1 wherein a majority of the end groups. of the fluorotelomer are derived from a secondary alcohol or derivative thereof.

3. The composition of claim 2 wherein the fluoroalkene contains 2 to about 10 carbon atoms.

4. The composition of claim 3 wherein the fluoroalkene contains 2 to 3 carbon atoms.

5. The composition of claim 4 wherein the secondary alcohol has 4 to about 12 carbon atoms and an α-hydrogen.

6. The composition of claim 5 wherein the secondary alcohol is 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, 2-butylacetate, cyclohexanol, 1-methoxy-2-propanol, 1-methoxy-3-butanol, 1-methoxy-2-pentanol, 1-methoxy-2-propanol acetate ester, or combinations of two or more thereof.

7. The composition of claim 1 wherein the moisture-curable silicone has terminal alkoxy, carboxy, or amino groups.

8. The composition of claim 7 wherein the moisture-curable silicone is a polyorganosiloxane.

9. The composition of claim 8 wherein the polyorganosiloxane is a methoxy-terminated siloxane selected from polydimethylsiloxane, polymethylhydrogensiloxane, polysilsesquioxane, polytrimethylsiloxane, polydimethylcyclosiloxane, or combination of two or more thereof.

10. The composition of claim 1 wherein the catalyst has the formula M(OR²)₄where M is zirconium or titanium and each R²is alkyl, cycloalkyl, alkaryl, or hydrocarbon radical containing from about 1 to about 30 carbon atoms per radical.

11. The composition of claim 1 wherein the catalyst is zirconium acetate, zirconium propionate, zirconium butyrate, zirconium hexanoate, zirconium 2-ethyl hexanoate, zirconium octanoate, tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, tetrabutyl zirconate, titanium acetate, titanium propionate, titanium butyrate, titanium hexanoate, titanium 2-ethyl hexanoate, titanium octanoate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, or combination of two or more thereof.

12. The composition of claim 11 wherein the catalyst is tetraisopropyl titanate, tetrabutyl titanate, or a combination thereof.

13. The composition of claim 1 wherein the solvent is aromatic hydrocarbon, alkane, alcohol, ketone, ester, ether, inorganic solvent, water, and combinations of two or more thereof such as, for example, xylene, benzene, toluene, n-heptane, octane, cyclohexane, dodecane, methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, dipropylene glycol, dipropylene glycol methyl ether, methylene chloride, methylene dichloride, ethylene dichloride, carbon tetrachloride, chloroform, perchloroethylene, ethyl acetate, tetrahydrofuran, dioxane, white spirit, mineral spirits, naphtha, or combination of two or more thereof.

14. The composition of claim 1 further comprising a silicone intermediate.

15. The composition of claim 14 wherein the silicone intermediate is hydroxy-terminated polyorganosiloxane.

16. The composition of claim 15 wherein the silicone intermediate comprises a volatile siloxane.

17. A method to ease separation of a workpiece from a substrate comprising applying the release agent composition of claim 1 to a surface of the workpiece, the substrate, or both.

18. A method for improving the release properties of molds removed from a pattern or cores from a core box comprising applying a composition comprising (a) a crosslinkable fluorotelomer comprising repeat units derived from a fluoroalkene; (b) a moisture-curable silicone; (c) a catalyst; and (d) a solvent to a surface of a pattern or core box.

19. The method of claim 18 wherein a majority of the end groups of the fluorotelomer are derived from a secondary alcohol or derivative thereof.

20. The method of claim 19 wherein the catalyst has the formula M(OR²)₄where M is zirconium or titanium and each R²is alkyl, cycloalkyl, alkaryl, or hydrocarbon radical containing from about 1 to about 30 carbon atoms per radical.

21. The method of claim 20 wherein the release agent composition further comprises a silicone intermediate.

22. A method to prevent squeaking of rubber weatherstripping comprising applying the release agent composition of claim 1 to a surface of weatherstripping.

23. A method to protect surfaces from foreign matter comprising applying the release agent composition of claim 1 to a surface of a substrate.

24. The method of claim 23 wherein the substrate is wood, metal, plastic, rubber, stone, cement, concrete, glass, fiber, tile, or combination of two or more thereof.

25. A method to reduce formation of rust on a steel surface comprising applying the release agent composition of claim 1 to a steel surface.