Paintable organopolysiloxane mold release compositions and processes for their use

Silicone mold release compositions which are a stable blend of hydrophobic-modified organopolysiloxane and an aminoorgano- or mercaptoorgano-functional organopolysiloxane, or a solution in organic solvent of a stable or unstable blend, provide exceptional mold release properties while retaining paintability of molded parts.

TECHNICAL FIELD
 The subject invention pertains to organopolysiloxane mold release
 compositions which display enhanced paintability.
 BACKGROUND ART
 Mold release compositions have long been used to facilitate the release of
 molded polymer parts from molds. Particularly in the case of parts having
 complex shapes or deep sections, and more particularly in the case of
 polymers which display aggressive adhesion to the mold surface, production
 of parts without an effective mold release would not be possible.
 A wide variety of mold releases exist. Early mold releases relied on
 natural and synthetic waxes. Often, molds would have to be hand or machine
 buffed to obtain maximum release. Such mold release agents are not
 practical for modern high speed production rates. One advantage of such
 mold releases, however, is that they are often paintable without wiping or
 cleaning, and can be readily removed as well.
 Aqueous soap solutions and dispersions are sometimes used as mold releases.
 However, soaps are not highly effective, and cannot be used with moisture
 sensitive molding compositions such as polyurethane RIM unless allowed to
 thoroughly dry. If still moist, surface defects and local foaming may
 occur in polyurethane RIM.
 Polyurethane RIM has been especially problematic due to its natural
 tendency to adhere to molds. A considerable advance in RIM technology was
 the introduction of internal mold releases based on zinc stearate in
 conjunction with fatty substances such as fatty esters and epoxidized
 natural oils. These mold releases are incorporated into the reactive
 composition prior to molding. Unfortunately, in order to provide
 consistent, multiple releases, such internal mold releases must be used at
 high levels. For parts which must be painted, these high levels of use
 impair paintability. Decreasing the amount of internal mold release,
 however, increases the difficulty of release. Thus, such systems generally
 employ external mold releases in conjunction with internal mold releases.
 Organopolysiloxanes such as trimethylsiloxy-terminated polydimethylsiloxane
 fluids have proven to be effective mold release agents, and when used in
 conjunction with aminoalkyl and thioalkyl-functional organopolysiloxanes,
 as disclosed in U.S. Pat. Nos. 4,251,277 and 3,883,628 provide
 extraordinary release.
 Such organopolysiloxane fluids can be applied neat, in solution in organic
 solvent, or in the form of an aqueous emulsion. For pigmented moldings
 such as ski boots, roller blades, and the like, such mold releases are
 exemplary. Unfortunately, polydimethylsiloxane fluids are notorious for
 destroying paintability of molded parts, even after extensive wiping and
 washing operations. Common paint defects include uneven coverage,
 sometimes to the extent of large bare areas, orange peel, runs, sags, and
 particularly, fish eyes. The effects of such fluids on paintability is so
 severe, that some manufacturing plants ban all products containing
 polydimethylsiloxanes, even solid silicones such as gasketing material.
 Suppliers of O-ring seals and other products must frequently certify that
 their products contain no polydimethylsiloxanes.
 Efforts to retain the advantages of polydimethylsiloxanes as mold release
 agents while retaining paintability have been only partially successful.
 Modification of these siloxanes by replacing a portion of the methyl
 groups with relatively hydrophobic hydrocarbon groups, e.g. C.sub.4-30
 alkyl groups, phenyl groups, and in particular, with
 .alpha.-methylphenylethyl groups, has resulted in siloxane mold releases
 which are sometimes paintable immediately after demolding and without
 further post treatment such as wiping or washing, and which rather
 uniformly display good paintability after such post treatment. An example
 of such fluids is Wacker TN available from Wacker Silicones, Adrian, Mich.
 Similar mold releases are disclosed by Japanese Kokai JP 09012886 A2.
 Unfortunately, while exhibiting enhanced paintability, the aforementioned
 modified siloxanes are not nearly as efficient in their mold release
 properties as straight polydimethylsiloxanes that contain aminoorgano- or
 thiolorgano-functional organopolysiloxane. This is particularly the case
 where deep sections and/or aggressively adhering polymer systems are
 involved.
 It would be desirable to provide a mold release composition which is
 comparable in ease of mold release with polydimethylsiloxanes that contain
 aminoorgano- or thiolorgano-functional organopolysiloxane(s), while being
 paintable as well.
 DISCLOSURE OF INVENTION
 The present invention pertains to mixtures of organopolysiloxanes based on
 hydrophobically modified polydimethylsiloxane fluids and aminoorgano-
 and/or mercaptoorgano-functionalized organopolysiloxanes. These
 compositions provide both excellent release and paintability when prepared
 as stable compositions as described below. Surprisingly, unstable
 compositions which are not suitable as paintable mold releases by
 themselves are rendered highly effective when dissolved in organic
 solvent.
 BEST MODE FOR CARRYING OUT THE INVENTION
 The mold release compositions of the subject invention contain, as active
 ingredients, an organofunctional organopolysiloxane and a
 hydrophobic-modified polyorganosiloxane. The compositions may be applied
 neat, from solution, or as a dispersion. Neat products must display
 stability as hereinafter defined. The compositions may also include
 additional organopolysiloxanes, silanes, rheology control agents,
 surfactants, etc., but are very preferably devoid of polydimethylsilicone
 fluids, including silanol terminated polydimethyl fluids such as
 .alpha.,.omega.-dihydroxylpolydimethylsiloxanes; and polydimethylsiloxanes
 having terminal or pendant hydrolyzable alkoxy or acetoxy groups. Alkoxy
 groups or other groups which are not hydrolyzable or hydrolyze only slowly
 may be acceptable for use as hydrophobicizing groups if these groups
 contain an appropriate hydrophobe.
 The hydrophobic-modified polyorganosiloxane may be branched or linear, and
 contains moieties corresponding to:
EQU R.sub.a R.sub.b.sup.1 SiO.sub.1/2 (I)
EQU R.sub.a R.sub.b.sup.1 SiO.sub.2/2 (II)
EQU R.sub.a R.sub.b.sup.1 SiO.sub.3/2 (III)
 and
EQU SiO.sub.4/2 (IV)
 wherein
 R is lower alkyl or alkylene, optionally interrupted by ether oxygen or
 thloether sulfur, such as methyl, n-propyl, i-propyl, n-butyl, vinyl,
 methoxymethlyl, methoxyethyl, ethoxymethyl, ethoxyethyl, methoxypropyl,
 and 2-thiobutyl. R preferably contains 4 carbon atoms or less, more
 preferably 3 or less carbon atoms, and in particular, 1 or 2 carbon atoms.
 R.sup.1 is a C.sub.4 -C.sub.30 hydrophobic group optionally containing not
 more than one ether oxygen or thioether sulfur when the carbon content is
 less than C.sub.10, and in general not more than two ether oxygen or
 thioether sulfur atoms for C.sub.11 -C.sub.30 groups, in any case
 insufficient interspersed --O-- and/or --S-- to defeat the hydrophobicity
 of the R.sup.1 hydrophobicizing group. The hydrophobic nature of the
 R.sup.1 groups containing interspersed --O-- and --S-- atoms may be
 assessed by evaluating the paintability of molded parts prepared employing
 a mold release containing organofunctional polysiloxane and the candidate
 --O-- or --S-- containing hydrophobic-modified polysiloxane.
 Preferred examples of R.sup.1 are C.sub.4-30, preferably C.sub.6-20 alkyl,
 alkenyl, cycloalkyl, cycloalkenyl, aryl, alkaryl, and aralkyl groups.
 Non-limiting examples are 2-ethylhexyl, n-octyl, n-decyl, n-dodecyl,
 n-octadecyl, lauryl, stearyl, phenyl, tolyl, benzyl, phenylethyl,
 norbornenyl and particularly .alpha.-methylphenylethyl. Also particularly
 suitlable are alkylated phenyl and napthyl groups, e.g. 4-nonylphenyl,
 4-nonylphenylethyl, and 4-nonyl-2-methylphenylethyl, and the like, and
 alkyl-substituted cycloalkyl and cycloalkenyl such as 4-ethylcyclohexyl,
 4-nonylcyclohexyl, 4-methylcyclohexyl, 2-cyclohexylhexyl, and the like.
 The various R and R.sup.1 groups may be substituted or unsubstituted.
 Examples of suitable substituents are alkoxy, cyano, and halo, preferably
 cyano and chloro substituents. Trifluoromethyl and other haloalkyl groups
 are also suitable.
 It is possible that some of the R and/or R.sup.1 groups may be replaced by
 hydroxy, halo, hydrido, or alkoxy groups, but these are preferably absent,
 the amounts present being preferably no more than is unavoidable in the
 preparation of the hydrophobic-modified organopolysiloxane. Most
 preferably, R is methyl and R.sup.1 is phenyl, benzyl, phenylethyl, or
 .alpha.-methylphenylethyl. Other preferred R.sup.1 groups are --R.sup.2
 --R.sup.3 wherein R.sup.2 is an alkylene, cycloalkylene, or phenylene
 diradical, and R.sup.3 is phenyl, naphthyl, tolyl, and the like.
 Essentially, R.sup.1 may be any hydrophobic group which enhances
 paintability.
 In formulae I, II, and III, a, b, and c may be 0, 1, 2, or 3, and the sum
 of a+b is such so as to be 3 for formula I, 2 for formula II, and 1 for
 formula III. Preferably, the hydrophobic-modified organosiloxanes contain
 not more than 10 mol percent of formula IV (Q units), more preferably not
 more than 5 mol percent, and most preferably only unavoidable amounts of Q
 units. The hydrophobic-modified organopolysiloxanes also contain
 preferably no more than 20 mol percent of the units of formulae III (T
 units) more preferably no more than 10 mol percent, yet more preferably no
 more than 5 mol percent, and most preferably 2 mol percent or less, for
 example with no T-units or only those which are unavoidable.
 More preferably, the hydrophobic-modified organopolysiloxanes correspond to
 the formula
 ##STR1##
 wherein R.sup.2 is R or R.sup.1, and R.sup.2 is preferably methyl; or
 R.sup.2 is R.sup.3 or R.sup.4 ; wherein R.sup.3 is preferably an aryl or
 aralkyl group such as phenyl, tolyl, benzyl, phenylethyl, and in
 particular, .alpha.-methylphenylethyl; and wherein R.sup.4 is preferably a
 C.sub.18 -C.sub.20 alkyl, more preferably a C.sub.10 -C.sub.8 alkyl group.
 The two terminal methyl groups of formula V may also be replaced by
 R.sup.2, however, this is not preferred. Most preferably R.sup.2 is
 methyl.
 Most preferably, the hydrophobic-modified organopolysiloxanes are those
 corresponding to
 ##STR2##
 In the above formulae, x, y, and z are positive integers, preferably such
 that z is an integer from 3 to 30, more preferably 4 to 24, and most
 preferably 5 to 18, and x and y are integers of from 0 to about 1000, more
 preferably 3 to 250, and most preferably 4 to 60, with the proviso that
 the sum of x+y is at least 5, and the molecules have, on average, at least
 5 siloxy repeating units, preferably 10 to 100 repeating units, and most
 preferably 15 to 50 repeating units, corresponding to number average
 molecular weights of from greater than about 600 Da to about 600,000 Da or
 higher, and viscosities from about 10 cSt to about 20,000 cSt, preferably
 50 cSt to about 5000 cSt.
 The hydrophobic-modified organopolysiloxanes can be prepared by known
 methods, for example by hydrosilylation of 2-methylstyrene and like
 compounds, and terminal or non-terminal alkenes, and mixtures thereof,
 with organopolysiloxanes containing silicon-bonded hydrogen (SiH), for
 example organopolysiloxanes having terminal methylsilane or dimethylsilane
 groups, or internal methylhydrogensiloxy groups, in the presence of
 conventional hydrosilylation catalysts, particularly platinum catalysts.
 The hydrophobic-modified organopolysiloxanes may also be prepared by
 condensation reactions, for example by condensation of SiH functional
 organopolysiloxanes with chlorohydrocarbons with generation of HCl, or
 when appropriate, by direct synthesis. The molecular weight and viscosity
 may be adjusted by equilibration and condensation reactions known in the
 art. Preferably, polydimethylsiloxanes containing no hydrophobicizing
 groups are absent during equilibration.
 The organofunctional organopolysiloxanes which are a necessary component of
 the subject invention contain aminoorgano or mercaptoorgano functionality.
 In general, and in particular due to their mode of preparation, the
 organofunctional organopolysiloxanes may also contain hydrolyzable alkoxyl
 functionality. The aminoorgano and mercaptoorgano groups correspond
 generally to the formulae
EQU R.sup.6 HN--X-- and HS--X--
 where X is an Si-bound linking group, preferably an alkylene group
 optionally containing heteroatoms and heteroatom-containing groups such
 as, but not limited to
 ##STR3##
 and the like, and R.sup.6 is as defined below.
 The linking group X may also be a phenylene, cycloalkylene, aralkyl,
 alkaryl, or similar group, and in general contains from 1 to about 30
 carbon atoms, preferably 2 to 10 carbon atoms, and most preferably 3 to 5
 carbon atoms.
 Preferred aminoalkyl groups are those corresponding to the formula VI
EQU --R.sup.5 --[(NR.sup.6)--R.sup.7 ].sub.t NR.sup.8 R.sup.9 (VII)
 in which
 R.sup.5 and R.sup.7 are divalent hydrocarbon groups, and R.sup.6, R.sup.8,
 and R.sup.9 are hydrogen or C.sub.1-30 substituted or unsubstituted
 hydrocarbon groups, more preferably C.sub.1 -C.sub.18 hydrocarbon groups,
 optionally containing interspersed heteroatoms or heteroatom-containing
 groups, and
 R.sup.5 is preferably a divalent C.sub.1 to C.sub.18 hydrocarbon radical,
 R.sup.6 is preferably a hydrogen atom or an unsubstituted C.sub.1 to
 C.sub.18 alkyl or aryl radical, wherein alkyl and aryl with respect to
 R.sup.6 may also include aralkyl and alkaryl radicals, respectively,
 R.sup.7 is preferably a divalent C.sub.1 to C.sub.18 hydrocarbon radical,
 R.sup.8 is preferably a hydrogen atom or an unsubstituted C.sub.1 -C.sub.18
 alkyl or aryl radical, wherein alkyl and aryl with respect to R.sup.8 may
 also include aralkyl and alkaryl radicals, respectively,
 R.sup.9 is preferably a hydrogen atom or an unsubstituted C.sub.1 -C.sub.18
 alkyl or aryl radical, wherein alkyl and aryl with respect to R.sup.9 may
 also include aralkyl and alkaryl radicals, respectively, and
 t is preferably an integer from 0 to 6.
 Examples of divalent C.sub.1 - to C.sub.18 -hydrocarbon radicals
 represented by R.sup.5 and R.sup.7 are the methylene, ethylene,
 n-propylene, isopropylene, n-butylene, isobutylene, tert-butylene,
 n-pentylene, isopentylene, neopentylene, and tert-pentylene radicals;
 hexylene radicals such as the n-hexylene radical; heptylene radicals such
 as the n-heptylene radical; octylene radicals such as the n-octylene
 radical and isooctylene radicals such as the 2,2,4-trimethylpentylene
 radical; nonylene radicals such as the n-nonylene radical; decylene
 radicals such as the n-decylene radical; dodecylene radicals such as the
 n-dodecylene radical; and octadecylene radicals such as the n-octadecylene
 radical.
 Examples of C.sub.1 - to C.sub.18 -alkyl radicals R.sup.6, R.sup.8 and
 R.sup.9 are methyl radicals, ethyl radicals, propyl radicals, butyl
 radicals, cyclohexyl radicals, pentyl radicals, hexyl radicals, decyl
 radicals, dodedecyl radicals, and octadecyl radicals. Examples of C.sub.1
 to C.sub.18 aryl radicals represented by R.sup.6, R.sup.8 and R.sup.9 are
 benzyl radicals and naphthyl radicals.
 Preferred mercapto groups are those of the formula
EQU HS--R.sup.10 --,
 wherein R.sup.10 is an organic diradical corresponding to those derived
 from R.sup.5 and R.sup.7. Preferably, R.sup.10 is ethylene, n-propylene,
 n-butylene, and in general, C.sub.1 -C.sub.18 hydrocarbons optionally
 interspersed with --NH--, --NR--, --O--, --S--,
 ##STR4##
 ##STR5##
 or one of the hetroatoms-containing groups previously identified. More
 preferably, R.sup.10 is C.sub.2-6 alkylene, most preferably C.sub.2
 -C.sub.3 alkylene, and in particular, n-propylene.
 Suitable examples of R'(SR'").sub.y groups include--C.sub.2 SH, --CH.sub.2
 H.sub.4 SH,
 --C.sub.3 H.sub.6 SH, (HSCH.sub.2).sub.2 CHCH.sub.2 CH.sub.2 --,
 (HSCH.sub.2 CH.sub.2)(HSCH.sub.2)CH(CH.sub.2).sub.4 --,
 (HSCH.sub.2)CH.sub.2).sub.3 CCH.sub.2 CH.sub.2 --,
 (HSCH.sub.2 CH.sub.2)(HSCH.sub.2)CHCH(CH.sub.2 SH)CH.sub.2 CH.sub.2
 CH.sub.2 --,
 HS(CH.sub.2).sub.5 CH(CH.sub.2 CH.sub.2 SH)CH.sub.2 CH.sub.2 CH(CH.sub.2
 CH.sub.3)--,
 (HSCH.sub.2 CH.sub.2).sub.2 CHCH.sub.2 CH.sub.2 --,
 (HSCH.sub.2).sub.2 CHSCH.sub.2 CH.sub.2 CH.sub.2 --,
 (HSCH.sub.2).sub.2 (C.sub.2 H.sub.5) CCH.sub.2 SCH.sub.2 CH.sub.2 CH.sub.3
 --,
 (HSCH.sub.2).sub.3 CCH.sub.2 SCH.sub.2 CH.sub.2 CH.sub.2 --,
 (HSCH.sub.2)(HSCH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2)CHSCH.sub.2 CH.sub.2
 CH.sub.2 --,
 (HSCH.sub.2 CH.sub.2).sub.2 CHCH.sub.2 SCH.sub.2 CH.sub.2 CH.sub.2 --,
 (HSCH.sub.2).sub.2 (C.sub.2 H.sub.5)CCH.sub.2 SCH.sub.2 CH.sub.2
 S(SCH.sub.2).sub.3 --,
 (HSCH.sub.2).sub.3 CCH.sub.2 S(CH.sub.2).sub.3 S(CH.sub.2).sub.3 --,
 ##STR6##
 and the like.
 The aminoorgano or mercaptoorgano organofunctional groups are bonded to
 silicon atoms contained in the organopolysiloxanes, preferably
 organopolysiloxanes containing moieties analogous to the foregoing
 formulae I, II, III, and IV, but wherein substituents other than
 aminoorgano and mercaptoorgano garoups are preferably R groups, more
 preferably methyl groups or lower alkoxy groups whose presence is
 sometimes dictated by the synthetic method employed. The alkoxy group
 content is thus in general less than 20 weight percent, more preferably
 less than 10 weight percent, and in general between about 0.1 weight
 percent and 8 weight percent.
 The aminoorgano-functional fluids have amine equivalents of minimally about
 0.01 meq/g, more preferably minimally 0.1 meq/g, and most preferably
 minimally 1 meq/g, and a maximum of preferably about 7 meq/g, more
 preferably 3 meq/g. The mercaptoorgano-functional organopolysiloxanes
 generally contain in excess of 0.01 weight percent --SH groups, more
 preferably in excess of 0.1 weight percent, and preferably less than 5
 weight percent, more preferably less than 2 weight percent. Aminoalkyl-
 and mercaptoalkyl-functional, substantially linear polydimethylsiloxanes
 are preferred organofunctional organopolysiloxanes, most preferably those
 containing silsesquisiloxane groups having aminoorgano- or
 mercaptoorgano-functionality bonded thereto.
 The amino-functional and mercapto-functional organopolysiloxanes may be
 prepared by conventional methods, i.e. by hydrosilylation of unsaturated
 amines or mercaptans by hydrogen-functional organopolysiloxanes in the
 presence of a hydrosilylation catalyst. Such functional
 organopolysiloxanes are available commercially.
 It has been surprisingly discovered that not all blends of
 hydrophobic-modified organopolysiloxanes and organofunctional
 organopolysiloxanes are inherently suitable for use as mold releases. In
 particular, it has been discovered that suitability depends upon the
 physical stability of the blend.
 Physical stability is assessed by a simple test involving centrifuging a 50
 ml sample contained in a 50 ml conical centrifuge tube at 3000 rpm in an
 IEC Centra 8 Model 2476 centrifuige, manufactured by International
 Equipment Company. An angle rotor, 822a, is used. The sample is
 centrifuged for one hour. Samples are carefully drawn from the top and
 bottom following centrifuging, and analyzed for organofunctional group
 content. Standard analyses are used, for example acid titration for
 amino-functional siloxanes and silver nitrate titration for
 mercapto-functional siloxanes. Other analytical methods are suitable as
 well. A blend is stable if the mole ratio of functional groups in the top
 compared to the bottom is between 0.9 and 1.1, and preferably in the range
 of 0.93 to 1.07.
 If the blend is stable, as described above, it will be suitable as an
 efficient mold release while also being paintable. Preferred stable blends
 contain from 0.02 to about 8 weight percent organofunctional
 organopolysiloxane, more preferably 0.05 to about 3.0 weight percent.
 Blends which are not stable are less effective as mold releases and also
 require vigorous cleaning in order to be painted successfully. Thus,
 stable, neat blends comprising organofunctional- and
 hydrophobically-modified organopolysiloxanes constitute one embodiment of
 the subject invention.
 It has also been surprisingly discovered that blends of organofunctional-
 and hydrophobically-modified organopolysiloxanes which are not stable,
 i.e. those outside the top/bottom mol ratio of 0.9 to 1.1, will provide
 excellent mold release and yet be paintable, if dissolved in organic
 solvent in a concentration of about 10 weight percent or less, preferably
 less than 6 weight percent. Preferred organic solvents include aromatics
 such as toluene and xylene; alcohols such as isopropyl alcohol and
 n-propanol; aliphatic solvents such as mineral spirits, petroleum ether,
 heptane, cyclohexane, and the like; and volatile siloxanes such as
 hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane. The stability
 of these blends should be such that the top/bottom mol ratio is preferably
 between 0.5 and 1.4, and more preferably 0.8 to 1.2 when the concentration
 of siloxane components in the solvent is less than about 10 weight
 percent, and more preferably less than 6 weight percent. Exemplary blends
 are separation-prone blends containing from 3 weight percent to about 20
 weight percent organofunctional organopolysiloxane, more preferably 3
 weight percent to about 10 weight percent based on total organosilicon
 compound content. Stable blends may be applied from solvent as well.
 Unexpectedly, however, unstable, solvent-based formulations have proven to
 be superior to stable, solvent-based formulations when the concentrations
 of release agent blend is lower than about 10 weight percent.
 The mold release agents of the subject invention, whether stable or
 unstable, may also be applied from aqueous emulsions or dispersions (both
 termed "emulsions" herein). Most preferably, microemulsions, i.e. those
 with dispersed phase particle sizes in the range of less than 1 .mu.m are
 preferred. Such emulsions are prepared by conventional methods, and
 preferably employ a non-ionic surfactant having an HLB of 11-14, and
 preferably 12-13. Mixtures of surfactants having high and low HLB may also
 be used. The amount of surfactant is conventional, and generally ranges
 from about 3 weight percent to about 8 weight percent, more preferably 4
 weight percent to 6 weight percent for an emulsion that contains 60 weight
 percent of the blend of this invention.
 The amount of mold release employed in a molding operation will depend upon
 the material of which the mold is constructed, its surface finish, depth
 of section, molding temperature, etc., all well known to those skilled in
 the art. The amount will also depend upon the polymer being molded, with
 aggressively adhering polymers such as polyurethane RIM and epoxy
 generally requiring greater amounts. Polymers or their precursor reactive
 systems which contain internal mold releases, may require less mold
 release. The actual amount can be determined by simple trial error
 techniques. If necessary, neat mold release compositions can be diluted
 with a suitable solvent or emulsificated into water. The solutions and
 emulsions can be further diluted as necessary.
 Additional mold release substances such as fatty alcohols, fatty esters,
 metal fatty carboxylates and soaps, etc., can be added if desired. Waxes,
 both natural and synthetic, may be added neat, in solution, or as a
 dispersion. Polydimethylsiloxane fluids may not, in general, be added,
 unless it is desired to employ the mold release for moldings which are not
 to be painted.
 Additives, which may be useful, include hydrophobic silica with very small
 particle size, i.e. silica having a surface area greater than 40 m.sup.2
 /g, preferably greater than 100 m.sup.2 /g. Preferably, any solid,
 non-soluble additives are present in amounts of less than 5 weight
 percent, more preferably less than 2 weight percent, in order to avoid
 buildup on the mold surface or surface contamination of the molded part.
 Organic dyestuffs may be added to assist in determining where complete mold
 coverage has been obtained. Dyes are preferably absent, however.
 Organic and inorganic viscosifiers may be useful, particularly for aqueous
 emulsions. Examples of suitable viscosifiers are the various vegetable
 gums, i.e. carrageenan, tragacanth, guar, acacia, and the like; various
 alkylated and carboxylated celluloses, such as carboxymethyl- and
 carboxypropylcellulose; polyacrylates, in particular polyacrylic acids and
 their copolymers, such as the various Carbopol.TM. and Acrysol.TM.
 polymers; and inorganic thickeners such as finely divided silicas and clay
 materials. Associative thickeners may also be useful. Examples of
 associative thickeners include hydrophobic polymers terminated with
 hydrophilic and/or polar groups, and in particular,
 polyoxyethylene/polyoxypro-pylene copolymers terminated with C.sub.8-30
 oxyalkylene moieties.

Having generally described this invention, a further understanding can be
 obtained by reference to certain specific examples which are provided
 herein for purposes of illustration only and are not intended to be
 limiting unless otherwise specified.
 In the Examples which follow, a two part polyurethane molding composition
 is chosen due to its aggressive adhesive properties. A mold consisting of
 a cold rolled steel cylinder with a closed bottom, open top, and a height
 of one inch (2.54 cm) is used as a mold. The side walls are c.a. 0.25 inch
 (0.6 cm) thick. Candidate mold releases are applied liberally by brush,
 and fifteen grams of reactive polyurethane consisting of 69.4% by weight
 of Conthane.RTM. TU-401 Part A and 30.6% of Conthane.RTM. TU-401 Part B.
 both available from Tool Chemical Co., Madison Heights, Mich., are poured
 into the mold and allowed to cure for 2 hours at 80.degree. C. in a forced
 air oven. Prior to pouring of the reactive polyurethane into the mold, the
 head of a 5/16 inch (0.8 cm) diameter bolt is suspended into the center of
 the mold so that the head will be encapsulated. The opposite end of the
 bolt has a ring to enable withdrawal of the molded part from the mold. In
 some examples, open aluminum molds are used instead.
 Mold release, or mold release component "Organosilicone Fluid L-42",
 available from Witco Corporation, Organosilicones Group, is believed to be
 a polyorganosiloxane containing methyl groups and
 .alpha.-methylphenylethyl groups bonded to the silicon atoms. Mold release
 or mold release component "Release Agent TN," available from Wacker
 Silicons, Adrian, Mich., is believed to be a similar organopolysitoxane
 containing methyl groups, phenylethyl groups, and dodecyl groups bonded to
 silicon. Both of these release agents correspond to the
 "hydrophobically-modified organopolysiloxanes" of the present invention.
 COMATIVE EXAMPLE C1
 A commercial mold release Organosilicone Fluid L-42 is applied to the mold
 prior to pouring in and curing the polyurethane. The molded part is
 allowed to cool to room temperature prior to determining the force
 required to remove the part from the mold. A Chatillon.TM. hand held gauge
 is attached to the ring and tension applied. The maximum force required
 for removal is noted. The part could not be removed. It had to be cut from
 the mold. The L-42 fluid provided no release.
 COMATIVE EXAMPLE C2
 The procedure of Comparison Example 2 is repeated except that Release Agent
 TN produced by Wacker Chemie is used instead of the L-42. The molded part
 could not be removed from the mold. The molded part has to be cut out of
 the mold. The release agent TN provides no release with this mold and this
 polymer system.
 COMATIVE EXAMPLE C3
 The procedure of Comparison Example C1 is repeated except a thin walled
 open aluminum dish is used for the mold and a bolt is not used. Release
 Agent TN produced by Wacker Chemie is used as the mold release. The
 aluminum must be separated from the part using pliers. It is very
 difficult to separate the part from the mold, which is torn into pieces as
 it is removed from the part. The molded part is painted with a red
 automotive acrylic lacquer, but the paint does not cover the part well.
 Another part is molded and separated from an aluminum dish and the part is
 wiped with a paper towel. The molded part is painted with a red automotive
 acrylic lacquer as before. A good coating is obtained and is free from
 orange peel and fish eye defects.
 COMATIVE EXAMPLE C4
 The procedure of Comparison Example C1 is repeated three times except that
 a blend consisting of 0.75 weight percent aminofunctional
 dimethylpolysiloxane and 99.25 weight percent methyl terminated
 dimethylpolysiloxane having a viscosity of 350 cSt is the release agent
 used. The aminofunctional dimethylpolysiloxane fluid has an amine content
 of 0.00014 equivalents per gram (0.14 meq/g), a methoxy content of 0.6
 weight percent, has a viscosity of about 400 cSt, and an amine
 functionality which is a silsesquioxane group containing an
 aminoethylaminopropyl group. Only 1 lb of force is required to remove the
 part from the mold. The part is painted with no cleaning and the coating
 obtained is very irregular containing many fish eyes. Another part is
 wiped with a paper towel and then painted. While it is better than the
 first painted part, it still has many surface defects. The part is
 scrubbed with Citrikleen.RTM., a Penetone Corporation product, and then is
 washed with water. The part is dried and then painted. Some fish eyes
 remain on the surface. This example illustrates the need for rigorous
 cleaning of parts molded with polysiloxanes that contain
 polydimethylsiloxane groups.
 COMATIVE EXAMPLE C5
 The procedure of Comparison Example C1 is repeated except the release
 composition is a blend consisting of 1 weight percent of a methoxy
 terminated dimethylpolysiloxane fluid that has a viscosity of about 12 cSt
 and 99 weight percent Release Agent TN described above. The
 dimethylpolysiloxane contains 7.4% methoxy groups. The test is done in
 triplicate. About 10 lbs of force is required to remove two of the parts.
 The third part would not release. This example demonstrates that the
 aminoorgano and/or mercaptoorgano functional groups of the subject
 invention are necessary to achieve good release. The parts are not
 painted.
 COMATIVE EXAMPLE C6
 The procedure of Comparison Example C5 is repeated except that the release
 composition first is dissolved in toluene, to a concentration of 10 weight
 percent. Two of the molded parts could not be separated from the molds.
 The third required 27.5 lbs of force to be removed. The parts are not
 painted. This example further demonstrates the necessity of the subject
 invention functional groups to achieve low release force, and also
 demonstrates that dilution with solvent normally results in molded parts
 adhering, more aggressively to the molds.
 COMATIVE EXAMPLE C7
 The procedure of Comparison Example C3 is followed. A solution consisting
 of 10 weight percent aminoftinctional dimethylpolysiloxane and 90 weight
 percent xylene is the release composition used. Three urethane parts are
 molded. The mold has to be torn into pieces as it is removed from the
 urethane part. The first part is painted with no cleaning and the coating
 obtained is very irregular containing many fish eyes. Another part is
 wiped with a paper towel and then painted. Its appearance is similar to
 the first part's appearance. It still has many surface defects. The third
 part is scrubbed with Citrikleen.RTM., a Penetone Corporation product, and
 then is washed with water. The part is dried and then painted. The part
 has multiple fish eyes. This example shows that even with vigorous
 cleaning the aminofunctional dimethylpolysiloxane is not removed from the
 part, in addition to being a poor release agent.
 EXAMPLE 1
 A blend (A) is prepared by mixing 1 weight percent of an aminofunctional
 dimethylpolysiloxane with 99 weight percent Organosilicone Fluid L-42
 produced by Witco Corporation, Organosilicones Group. A second blend (B)
 is prepared by mixing 1 weight percent of an aminofunctional
 dimethylpolysiloxane with 99 weight percent Release Agent TN produced by
 Wacker Chemie. The aminofunctional dimethylpolysiloxane fluid has an amine
 content of 0.0014 equivalents per gram (1.4 meq/g), a methoxy content of 7
 weight percent, a viscosity of about 20 cSt, and an amine functionality
 which is a silsesquioxane group containing an aminoethylaminopropyl group.
 The (A) blend is clear and the (B) blend is cloudy. Both blends are
 formulations within the scope of the invention.
 Each blend is applied to two molds and the procedure of Comparison Example
 C1 is followed to make molded parts. One part is painted immediately and
 the second part is painted after the surface of the part is wiped with a
 paper towel. The part molded with the (A) blend has a few minor defects on
 the unwiped part. The wiped part has no surface defects. The part molded
 with the (B) blend has several surface defects on the unwiped part. The
 wiped part is free of surface defects. Each part requires one pound of
 force to remove them from the mold. Excellent release is obtained.
 The (B) blend is centrifuged for one hour at 3000 rpm. A sample from the
 top and bottom is titrated for amine content. The top contains 0.00016
 equivalents per gram and the bottom contains 0.00017 equivalents per gram.
 The ratio of the functional group in the top to ratio of the functional
 group in the bottom is 0.94.
 EXAMPLE 2
 A blend (C) is prepared by mixing 1 weight percent of a
 mercaptan-functional dimethylpolysiloxane with 99 weight percent Release
 Agent TN. The mercaptan-functional dimethylpolysiloxane contains about 0.8
 weight percent of SH groups, has a viscosity of about 70 cSt, and the
 mercaptan functionality is borne by a silsesquioxane group having an
 attached mercaptopropyl group. The resultant cloudy blend is centrifuged
 for one hour at 3000 rpm. A sample is withdrawn from the top and bottom.
 The mercaptan (SH) content is determined by titrating the blend with
 silver nitrate. The top is found to have 0.008 weight percent SH and the
 bottom is found to have 0.008 weight percent SH. The ratio of functional
 groups in the top to functional groups in the bottom is 1.0. Two urethane
 parts are prepared following the procedure of Comparison Example C1. One
 pound of force is required to remove the parts from the molds. The first
 part is painted and the coating, is very uneven and the paint does not
 cover the part effectively. The second part is wiped before it is painted
 and an even coating is obtained.
 EXAMPLE 3
 A blend (D) is prepared by mixing 3 weight percent of the mercaptan
 functional dimethylpolysiloxane of Example 2 with 97 weight percent
 Release Agent TN. The result cloudy blend is centrifuged for one hour at
 3000 rpm. A sample is withdrawn from the top and bottom. The mercaptan
 (SH) content is determined by titrating the blend with silver nitrate. The
 top is found to have 0.013 weight percent SH and the bottom is found to
 have 0.026 weight percent SH. The ratio of the functional groups in the
 top to functional groups in the botom is 0.5. Two urethane parts are
 prepared following the procedure of Comparison Example C1. One pound of
 force was required to remove the parts from the molds. The first part was
 painted and the coating was very uneven and the paint does not cover the
 part effectively. The second part is wiped before it is painted. Orange
 peel and fish eyes are very apparent. A poor coating is obtained.
 The blend (D) is mixed with xylene to a 10 weight percent concentration.
 Two urethane parts are prepared following the procedure of Comparison
 Example C1. A force of about 5 pounds is required to remove the parts from
 the mold. The first part is painted and a good coating is obtained. The
 second part is wiped and it is then painted. An excellent coating is
 obtained.
 EXAMPLE 4
 The blend (B) from Example 1 is mixed with xylene to a 10 weight percent
 concentration. The resultant solution is applied to two molds and two
 urethane parts are molded following the procedure of Comparison Example
 C1. The first part is painted and an excellent coating is obtained. A
 release force of 8.3 pounds is required to remove the urethane parts from
 the molds. The procedure is repeated with a 5 weight percent solution of
 (B) in xylene. A force of 30 pounds does not remove the part from the
 mold. The xylene solution does not contain enough mold release, although
 it may be suitable for less aggressively adhering polymers, e.g.
 polypropylene.
 EXAMPLE 5
 A blend (F) is prepared by mixing 5 weight percent aminofunctional
 dimethylpolysiloxane with 95 weight percent Release Agent TN produced by
 Wacker-Chemie. The aminofunctional dimethylpolysiloxane fluid has an amine
 content of 0.0014 equivalents per gram (1.4 meq/g), a methoxy content of 7
 weight percent, a viscosity of about 20 cSt, and has amine functionality
 in silsesquioxane groups containing an aminoethylaminopropyl group. The
 (F) blend is cloudy. The blend is centrifuged for one hour at 3000 rpms. A
 sample from the top and bottom is titrated for amine content. The top
 contains 0.000067 equivalents per gram and the bottom contains 0.000085
 equivalents per gram. The ratio of functional groups in the top to
 functional groups in the bottom is 0.79.
 A solution consisting of 5 weight percent of the (F) blend in xylene is
 applied to two molds and the procedure of Comparison Example C1 is
 followed to make molded parts. One part is painted immediately and the
 second part was painted after the surface of the part is wiped with a
 paper towel. The part molded with the blend has a few minor defects on the
 unwiped part. The wiped part has no surface defects. Each part requires
 4.3 pounds of force to remove them from the mold.
 EXAMPLE 6
 A blend (G) is prepared by mixing 1 weight percent aminofunctional
 dimethylpolysiloxane and 99 weight percent Release Agent TN produced by
 Wacker-Chemie. The aminofunctional dimethylpolysiloxane fluid has an amine
 content of 0.00014 equivalents per gram (0.14 meq/g), a methoxy content of
 0.6 weight percent, a viscosity of about 400 cSt, and bears silsesquioxane
 groups containing an aminoethylaminopropyl group. The blend is cloudy. The
 blend is applied to two molds and the procedure of Comparison Example C1
 is followed to make molded parts. One part is painted immediately and the
 second part is painted after the surface of the part is wiped with a paper
 towel. The unwiped part has numerous surface defects. The wiped part has
 no surface defects. Each part requires one pound of force to remove them
 from the mold. Excellent release is obtained.
 The (G) blend is centrifuged for one hour at 3000 rpms. A sample from the
 top and bottom is titrated for amine content. The top contains 0.000002
 equivalents per gram and the bottom contains 0.000002 equivalents per
 gram. The ratio of the functional group in the top to ratio of the
 functional group in the bottom is 1.0.
 EXAMPLE 7
 A blend (H) is prepared by mixing 1 weight percent aminofunctional
 dimethylpolysiloxane and 99 percent Release Agent TN produced by
 Wacker-Chemie. The aminofunctional dimethylpolysiloxane fluid has an amine
 content of 0.0005 equivalents per gram (0.5 meq/g), a methoxy content of
 2.6 weight percent, a viscosity of about 60 cSt, and contains
 silsesquioxane groups containing an aminoethylaminopropyl group. The blend
 is cloudy. The blend is applied to two molds and the procedure of
 Comparison Example C1 is followed to make the molded parts. One part is
 painted immediately and the second part is painted after the surface of
 the part was wiped with a paper towel. The unwiped part has numerous
 surface defects. The wiped part has no surface defects. The parts require
 1.8 pounds of force to remove them from the mold. Excellent release is
 obtained.
 The (G) blend is centrifuged for one hour at 3000 rpms. A sample from the
 top and bottom is titrated for amine content. The top contains 0.000005
 equivalents per gram and the bottom contains 0.000005 equivalents per
 gram. The ratio of functional groups in the top to functional groups in
 the bottom is 1.0.
 EXAMPLE 8
 A blend (I) is prepared by mixing 1 weight percent of a methyl terminated
 aminofunctional dimethylpolysiloxane with 99 weight percent Release Agent
 TN produced by Wacker Chemle. The aminofunctional dimethylpolysiloxane
 fluid has an amine content of 0.00014 equivalents per gram (0.14 meq/g), a
 viscosity of about 500 cSt, and contains silsesquioxane groups containing
 an aminoethylaminopropyl group. The blend is cloudy. The blend is applied
 to two molds and the procedure of Comparison Example C1 is followed to
 make molded parts. One part is painted immediately and the second part is
 painted after the surface of the part is wiped with a paper towel. The
 unwiped part has numerous surface defects. The wiped part has no surface
 defects. The parts require 1 pound of force to remove them from the mold.
 Excellent release is obtained.
 EXAMPLE 9
 An emulsion of the (B) blend is prepared by mixing 7.0 parts of nonionic
 surfactant with 6 parts of water. To the resultant mixture is added the
 (B) blend, 60 parts. To that mixture is added slowly 33 parts of water. A
 stable white emulsion is obtained, with a dispersed phase particle size of
 309 nanometers. The emulsion is applied to a mold as described in
 Comparison Example C1. The mold is allowed to dry and then a urethane part
 is made in accordance to the procedure of Comparison Example C1. The
 urethane part could be separated from the mold.
 The foregoing experiments demonstrate that hydrophobically modified
 organopolysiloxanes do not provide high release capability, particularly
 when used with reactive polyurethanes in deep section molds (Comparative
 Examples C1-C3). However, if removal from the mold is possible at all, the
 parts are not immediately paintable, but may be successfully painted
 following wiping of the surface with a dry towel or rag (Comparative
 Example C3).
 The experiments also show that blends of amino-functional fluids and
 conventional polydimethylsiloxane fluids (Comparative Example C4) provide
 excellent release, but exceptionally poor paintability. Such mold release
 compositions are not useable in many applications, for example as mold
 releases for automotive polyurethane RIM parts.
 In Comparison Example C5, the importance of aminoalkyl- or
 mercaptoalkyl-functional groups in the organofunctional organopolysiloxane
 are demonstrated. Substitution of a methoxy-functional siloxane for the
 organofunctional siloxanes of the subject invention required a higher than
 desired release force, when parts could be released at all. Comparative
 Example C6 illustrates that applying the neat mold release of Comparative
 Example C5 dissolved in solvent does not improve the release, rather, the
 part adheres more aggressively to the mold.
 Comparison Example C7 demonstrates that aminoalkyl-functional fluids alone
 are very inefficient mold release agents. Despite employing a shallow
 section mold, the mold must be destroyed while being removed from the
 part. Moreover, the part exhibited almost complete failure with respect to
 paintability, even after cleaning with a powerful cleaning agent and
 washing with water.
 Examples 1 and 2 demonstrate the effectiveness of neat, stable blends of
 hydrophobic-modified orgyanopolysiloxane and organofunctional
 organopolysiloxane. Both the A and B examples exhibited exceptional
 release properties as well as good paintability after wiping. Example 6
 demonstrates that a stable blend containing only one tenth the amount of
 aminoalkyl-functionality as used in Example 1 still provides exceptional
 release. Example 7 is intermediate to these examples in terms of
 aminoalkyl-functionality.
 Example 3 demonstrates that unstable (top/bottom functional group mol ratio
 0.5) blends of hydrophobic-modified organopolysiloxane and
 organofunctional organopolysiloxane provide excellent mold release despite
 the instability, but are quite deficient as to paintability. Surprisingly,
 however, upon dilution with solvent, a modest increase in release force is
 observed, but paintability is restored. Unstable blends are suitable when
 dissolved in solvent. Example 5 illustrates that unstable (top/bottom mol
 ratio 0.79) blends are satisfactory if dissolved in solvent.
 Example 4 illustrates that the release force may be altered by increasing
 or decreasing solvent content of mold release solutions. It is noted in
 general that higher solvent content, and indeed the presence of any
 solvent, increases the force required to release the part. Example 9
 indicates that aqueous emulsions of the subject compositions also function
 as effective mold release compositions.
 The invention disclosed herein can be practiced with any combination of
 named, necessary ingredients, particularly those identified as
 "preferred", to the exclusion of other ingredients named or unamed. The
 necessary ingredients comprise a hydrophobic-modified organopolysiloxane
 and an oranofunctional organopolysiloxane, as herein defined, in a neat
 stable blend, or a stable or unstable blend dissolved in organic solvent
 or emulsified to form an aqueous dispersion. By the terms "a" and "an" are
 meant "one or more" unless the context clearly indicates otherwise.
 By the term "unstable analog of" in reference to a stable composition is
 meant a different composition in terms of ingredient amounts, molecular
 weight, hydrophobic group content, functional group content or other
 property or composition or combination thereof, but belonging to the same
 general class of composition, the unstable composition having a
 "top/bottom mol ratio" outside the range of 0.9 to 1.1. By "top/bottom mol
 ratio" is meant the mol ratio of functional groups in the top and bottom
 of a sample after centrifugation as defined previously.
 While embodiments of the invention have been illustrated and described, it
 is not intended that these embodiments illustrate and describe all
 possible forms of the invention. Rather, the words used in the
 specification are words of description rather than limitation, and that
 various changes may be made without departing from the spirit and scope of
 the invention.