Paper release compositions having improved adhesion to paper and polymeric films

Description of equivalent WO 2004071765 A2

0001PAPER RELEASE COMPOSITIONS HAVING IMPROVED ADHESION TO PAPER AND POLYMERIC FILMS

FIELD OF THE INVENTION

0003The present invention relates to curable alkenyl based silicone release coating compositions having improved adhesion to paper and polymeric substrates. The present invention also relates to additives that improve adhesion of silicone release coating compositions to paper and polymeric substrates. Furthermore the present invention relates to the process for making a silicone release coating with improved adhesion to paper and polymeric substrates.

BACKGROUND OF THE INVENTION

0005Curable silicone compositions are applied to substrates to aid in the release of adhesive materials thereon. . Laminates comprising a release coated paper or polymeric film with a pressure sensitive adhesive and a sheet material that can be a decorative lamina or label are used by stripping off the release liner, which is discarded, and affixing the lamina or label onto a surface.

0006Typically these release compositions cure by one of two mechanisms, thermal curing or photo-catalytic curing. Thermally curing release systems generally are comprised of the following compositions:

0007(A) a linear alkenyl substituted polysiloxane polymer that is the primary component or base polymer of the curable composition;

0008(B) a hydride functional cross-linking silicone, typically a methyl hydrogen siloxane polymer, copolymer or oligomer;

0009(C) an addition cure hydrosilylation catalysts, typically either a platinum or rhodium based catalyst;

0010(D) a cure inhibiting compound or mixtures thereof to increase the useful life of the coating bath. The alkenyl functional silicone polymer release compositions typically used fall into one of two categories:

00111) a linear alkenyl chain-stopped polymer:

0012MviD_xM^vi 4)

0013where M^V1 indicates an alkenyl chain-stopping M group or

00142) multi-functional alkenyl copolymers:

0015MviD_xDvi_yMvi 5)

0016where D^vl indicates an alkenyl substituted D group. , The alkenyl chain stopped polymers, M^V1D_XM^V, generally cure faster than the multi-functional copolymers, M^vlD_xD^vlyM^vl. As release composites are delaminated, the formulations based on the linear alkenyl chain-stopped polymers show significant increases in the delaminating force necessary as delaminating speed increases. In contrast, while the multi-functional alkenyl polymers tend to have a slower curing speed the increase in delaminating force with increasing delaminating speed is not nearly as great proportionately.

0017While the general practice usually employs linear base polymers, (A), solventless, high solids content formulations have been described. As described in U. S. patent 4,448,815 ('815) a linear alkenyl siloxane base copolymer is a copolymer of:

0018(1) R_cRd¹Si(4-c-d)/2 1)

0019where R is generally an alkyl radical, R* is a low molecular weight olefinic substituent such as vinyl or allyl, c has value from 0 to 2 and the average of value of the sum c + d is 0.8 to 3; and

0020(2) R_nSiO₍₄__n)/2 2)

0021where R is generally an alkyl radical and n has a value of 0.8 to 2.5. The preferred base copolymer of the '815 patent has the following linear structure: (H₂C=CH)R₂Si-O-(R2Si-O-)_i -(RR¹Si-O-)j-SiR₂(H₂C-CH)

0022where the subscripts i and j are integers.

0023U. S. patent 4,774,111 ('111) describes a variation of the above linear copolymer where the R group in formula 2 is selected from alkyl and alkenyl radicals. The polymer of the '111 patent is defined as being substantially linear, i.e. having no more than a trace amount of T or Q groups. This substantially linear requirement for alkenyl functional heat curing silicone release compositions is repeated in U. S. patents 4, 772,515; 4,783,552 and 5,036, 117.

0024In contrast, the possibility of branched alkenyl polymers is admitted by the structural formulas recited in U. S. patent 4,057,596 ('596). In the '596 patent the composition comprises:

0025(A') a substantially linear vinyl chain stopped polymer;

0026(B') a linear methyl hydrogen polymer;

0027(C) a methyl vinyl polysiloxane having at least three vinyl groups per molecule;

0028(D') a methyl hydrogen polysiloxane having at least three hydride hydrogen atoms per molecule; and

0029(E') a platinum hydrosilylation catalyst.

0030Component (C) is described in the '596 patent as containing (H₂C=CH)(CH3)SiO₂/₂ (D^vi) , (H₂C=CH)(CH3)₂SiO_{1 2} (M ), and (H₂C=CH)SiO /₂ (Tvi) , units either singly or in combination with (CH3) SiO₂/₂ (D), (CH3)3SiOι/ (M), and (CH3)Siθ3/₂ (T). The optional inclusion of vinyl substituted T units and methyl T units permits the composition of the '596 patent to possess branched structures.

0031U. S. patent 4,386,135 describes a terminally unsaturated silicone polymer having the formula

0032R₄__aSi((R₂SiO-)_bOSiR₂R2)_a 3) where a may be 2, 3, or 4. When a = 4 the formula produces a Q resin. When a = 3, a T structure results and the structure possesses only a single branch point. When a = 2, the formula devolves to an alkenyl chain stopped linear polymer.

0033U. S. patent 5,468,826 teaches adhesion promoting additives comprised of organosiloxane copolymers having Si0_4/ units, alkoxy functional groups, epoxy or acrylo yalky groups and silicon hydride functionality. To those skilled in the art, it can be readily recognized that these have the disadvantage of increasing the release force during the delaminating process due to the resinous nature of the additive preventing low release force coatings from being available.

0034U. S. patent 3,873,334 teaches adhesion promoting additives comprised of acyloxy functional silanes, which additionally have silicon hydride or alkenyl functionality respectively. However, the acyloxy group liberated has the disadvantages of inhibiting addition cure, therefore slowing the addition curing process; liberating corrosive and objectionable odor hydrolysis products during the coating process. Furthermore, the acyloxy groups remaining in the release ,coating hydrolyzed over resulting in an undesirable interaction with the adhesive thus leading to undesirable delaminating release properties.

0035U.S. patent 5,567,764 teaches alkoxy containing alkenyl functional organopolysiloxanes as adhesion promoters for release coating onto polymeric films.

0036European patent 057984A2 teaches meth(acryl)oxy functional alkoxysilanes as adhesion promoters for release coatings on polymeric films.

0037Despite the above cited patents there still remains a need in the industry for release coating compositions, adhesion promoting additives which address the disadvantages of either stable adhesion to both paper and polymeric films, exhibit non-inhibiting effect on the curing, not liberate corrosive hydrolysis products, not exhibit objectionable odor during manufacturing of the laminate construction, not have hydrolysis products that would adversely interact with the adhesive used in the laminating construction, and a cost effective reproducible method of manufacture. SUMMARY OF THE INVENTION

0038The present invention provides for a release coating additive for a relase coating that provides adhesion to paper and polymeric films that does not inhibit the addition cure process, that does not liberate corrosive hydrolysis products, that does not exhibit an objectionable odor during the manufacturing of the laminate construction and that does not liberate hydrolysis products which adversely interact with the adhesive used in the laminating construction. Furthermore, the present invention also provides for a process of making an additive exhibiting stable adhesion on paper and polymeric films when added to a release coating.

0039The release compositions of the present invention comprise additives for improved anchorage of release coatings comprising:

0040(R_aSiO(₄-_a)/2)_n

0041where n is an interger greater than 3, a is from 1 to 3, R is an oxirane or epoxide, or carboxylic acid anhydride containing radical having from one to forty carbon atoms, monovalent hydrocarbon or hydrocarbonoxy radicals, hydride atoms, and with at least one oxirane or epoxide, or carboxylic acid anhydride and hydride being present on the molecule.

0042The compositions of the present invention further comprise a curable alkenyl silicone having the formula:

0043Mvi_aT_bD_cM_d

0044where

0045M^V1 = R¹3_pR2pSiO , where R¹ is selected from the group consisting of one to forty carbon monovalent hydrocarbon radicals and R² is selected from. the group consisting of two to forty carbon atom terminal olefinic monovalent hydrocarbon radicals, where p varies from 1 to 3;

0046T = R^Siθ3/₂ where R^ is selected from the group consisting of R¹ and R^; D = R⁴R⁵SiO₂/2 where R⁴ and R⁵ are each independently selected from the group consisting of R¹ and R²; and

0047M = R^SiOi^ where each R¹ is as previously defined and is independently selected; wherein a and b have values ranging from about 2 to about 5, c is an integer ranging from aboμt 50 to about 1,000 and d has a value ranging from 0 to 0.5, preferably from 0.25 to about 0.5, more preferably from about 0.35 to about 0.5 and most preferably from about 0.4 to about 0.5; which composition is preferably crosslinked by a substantially linear hydrogen siloxane selected from the group of compounds:

0048MD_eD'fM,

MD' M,

0050MD_eD'fM',

0051M'D_eD' M', and

0052M'D_eM' where

0053M = R'₃SiO_{1 2} ,

0054M' = H_gR'3_gSiOι /₂ , and

0055D - R'R'SiO₂/₂, and

0056D' = R'HSiO₂/ wherein each R' in M, M', D, and D' is independently selected from the group consisting of one to forty carbon monovalent hydrocarbon radicals wherein the subscripts e and f may be zero or positive whereby the sum of e and f ranges from about 10 to about 100 subject to the limitation that the sum of f and g is two or greater. The substantially linear, hydrogen siloxane is preferably selected from the group consisting of

0057MD_eD'^Vl, MD'fM,

0058and. mixtures thereof.

0059Preferably the substituents, R¹, of the curable alkenyl silicone are methyl, trifluoropropyl or phenyl and R² is preferably selected from the group consisting of two to ten carbon atom alkenyl groups.

0060Further, in the substantially linear hydrogen siloxane R' is preferably methyl, trifluoropropyl or phenyl.

0061The compositions of the present invention may be utilized as a solventless composition, a composition diluted by a suitable solvent, or as an aqueous emulsion and find particular use in release compositions for paper and polymeric films.

DETAILED DESCRIPTION OF THE INTENTION

0063Release coatings are part of a laminate wherein a release coating is coated upon a substrate. Generally substrates suitable for release coatings are selected from the group consisting of paper, polymeric films such as those consisting of polyethylene, polypropylene, and polyester.

0064The release compositions of the present invention comprise additives for improved anchorage of release coatings comprising additives for improved anchorage of release coatings comprising:

0065(R_aSiO₍₄-_a)/2)_n

0066where n is an integer greater than 3, a is from 1 to 3, R is an oxirane or epoxide, or carboxylic acid anhydride containing radical having from one to forty carbon atoms, monovalent hydrocarbon or hydrocarbonoxy radicals, hydride atoms, and with at least one oxirane or epoxide, or carboxylic acid anhydride and hydride being present on the molecule.

0067The present invention further provides for an alkenyl curable silicone composition of the foπnula Mvi_aτ_bD_cM_d

0068where

0069M^γi = R^3-. R2pSiOι/₂, where R* is selected from the group consisting of one to forty carbon monovalent hydrocarbon radicals and R² is selected from the group consisting of two to forty carbon atom olefinic monovalent hydrocarbon radicals, where p ranges from 1 to 3; T = R^Siθ3/₂ where R^ is selected from the group consisting of R! and R² ,D = <img file="WO2004071765A2_D0001.tif" /> are each independently selected from the groμp consisting of R and R², and M = R^SiOi^ where each R^ is independently selected and the subscripts a and b have values ranging from about 2 to about 5 and c is an integer ranging from about 50 to about 1,000 and d has a value ranging from 0 to 0.5, preferably from 0.25 to about 0.5, more preferably from about 0.35 to about 0.5 and most preferably from about 0.4 to about 0.5. Applicants define the term substantially branched to mean that the average number of T branching sites per alkenyl silicone molecule of (A) is at least two and preferably three. ,

0070The release compositions of the present invention comprise:

0071(A) additives for improved anchorage of release coatings comprising: '

0072(R_aSiO( -_a)/₂)n

0073where n is an interger greater than 3, a is from 1 to 3, R is an oxirane or epoxide, or carboxylic acid anhydride containing radical having from one to forty carbon atoms, monovalent hydrocarbon or hydrocarbonoxy radicals, hydride atoms, and with at least one oxirane or epoxide, or carboxylic acid anhydride and hydride being present on the molecule and

0074(B) an alkenyl silicone having the formula:

0075Mvi_aT_bD_cM_d

0076where the subscripts a, b, c, and d are as previously defined; (C) a hydrogen siloxane selected from the group of compounds:

0077MD_eD'fM

0078MD'fM,

0079MD_eD'fM'

0080M'D_eD'fM',

0081and

0082M'D_eM'

0083where M is as previously defined and

0084M' = H_g R'3_gSiOι/₂

0085D = R¹ R'SiO₂/₂ where each R' is independently selected and

0086D' = R'HSiO₂/₂

0087where R' is as previously defined, the subscripts e and f may be zero or positive wherein the sum of e and f ranges from about 10 to about 100 subject to the limitation that the sum of f and g is two or greater and

0088(D) a hydrosilylation catalyst comprising a metal selected from the group consisting of nickel, palladium, platinum, rhodium, iridium, ruthenium and osmium; and

0089(E) a cure inhibitor.

0090The amount of component (A) that is used in this invention range from about 0.1 to 5.0 parts, preferably from 0.5 to 4.0, and more preferably from about 0.5 to 3.0 parts.

0091The amounts of Components (B) and (C) that are used in the compositions of this invention are not narrowly limited. Said amounts, expressed n.terms of the ratio of the number of silicon-bonded hydrogen atoms of Component (B) to the number of silicon-bonded olefinic hydrocarbon radicals of Component (A), as is typically done, are sufficient to provide a value for said ratio of from 1/100 to 100/1, usually from 1/20 to 20/1, and preferably from 1/2 to 20/1.

0092Broadly stated, Component (D) of the composition of this invention is a catalyst component which, facilitates the reaction of the silicon-bonded hydrogen atoms of Component (C) with the silicon-bonded olefinic hydrocarbon radicals of Component (B) and can be any platinum-containing ^■ catalyst component. For example, Component (D) can be platinum metal; a carrier such as silica gel or powdered charcoal, bearing platinum metal; or a compound or complex of a platinum metal.

0093A typical platinum-containing catalyst component in the organopolysiloxane compositions of this invention is any form of chloroplatinic acid, such as, for example, the readily available hexahydrate form or the anhydrous form, because of its easy dispensability in organosiloxane systems. A particularly useful form of chloroplatinic acid is that composition obtained when it is reacted with an aliphatically unsaturated organosjlicon compound such as divinyltetramethyldisiloxane, as disclosed by U.S. Pat. No. 3,419,593 incorporated herein by reference.

0094The amount of platinum-containing catalyst component that is used in the compositions of this invention is not narrowly limited as long as there is a sufficient amount to accelerate a room temperature reaction between the silicon-bonded hydrogen atoms of Component (C) with the silicon-bonded olefinic hydrocarbon radicals of Component (B). The exact necessary amount of said catalyst component will depend upon the particular catalyst and is not easily predictable. However, for chloroplatinic acid said amount can be as low as one part by weight of platinum for every one million parts by weight of organosilicon Components (B) plus (C). Preferably said amount is at least 10 parts by weight, on the same basis.

0095For compositions of this invention which are to be used in the coating method of this invention, the amount of platinum-containing catalyst component to be used is preferably sufficient to provide from 10 to 500 parts by weight platinum per one million parts by weight of organopolysiloxane components (B) plus (C).

0096The hydrosilylation catalyst is selected from the group consisting of catalysts comprising a metal selected from the group consisting of nickel, palladium, platinum, rhodium, iridium, ruthenium and osmium or as taught in U.S. patents 3,159,601; 3,159,662; 3,419,593; 3,715,334; 3,775,452 and 3,814,730.

0097Inhibitors, component (E), for the platinum group metal catalysts are well known in the organosilicon art. Examples of various classes of such metal catalyst inhibitors include unsaturated organic compounds such as ethylenically or aromatically unsaturated amides, U.S. Patent No. 4,337,332; acetylenic compounds, U.S. Patent Numbers 3,445,420; 4,347,346 and 5,506,289; ethylenically unsaturated isocyanates, U.S. Patent No. 3,882,083; olefinic siloxanes, U.S. Patent No. 3,989,667; unsaturated hydrocarbon diesters, U.S. Patent No. 4,256,870; 4,476,166 and 4,562,096, and conjugated ene-ynes. U.S. Patent Numbers 4,465,81,8 and 4,472,563; other organic compounds such as hydroperoxides, U.S. Patent Number 4,061,609; ketones, U.S. Patent Number 3,418,731; sulfoxides, amines, phosphines, phosphites, nitriles, U.S. Patent Number 3,344,111; diaziridines, U.S. Patent No. 4,043,977; half esters and half amides, U.S. Patent 4,533,575; and various salts, such as U.S. Patent Number 3,461,185. It is believed that the compositions of this invention can comprise an inhibitor from any of these classes of inhibitors.

0098The inhibitors may be selected from the group consisting of ethylenically unsaturated amides, aromatically unsaturated amides, acetylenic compounds, ethylenically unsaturated isocyanates, olefinic siloxanes, unsaturated hydrocarbon diesters, unsaturated hydrocarbon mono-esters of unsaturated acids, conjugated ene-ynes, hydroperoxides, ketones, sulfoxides, amines, phosphines, phosphites, nitriles, arid diaziridines.

0099Preferred inhibitors for the compositions of this invention are the maleates and alkynyl alcohols.

0100The amount of Component (E) to be used in the compositions of this invention is not critical and can be any amount that will retard the above-described platinum-catalyzed hydrosilylation reaction at room temperature while not preventing said reaction at moderately elevated temperature, i.e. a temperature that is 25 to 50 °C above room temperature. No specific amount of inhibitor can be suggested to obtain a specified bath life at room temperature since the desired amount of any particular inhibitor to be used will depend upon the concentration and type of the platinum group metal- containing catalyst, the nature and amounts of Components (A) and (B). The range of Component (E) can be 0.1-10% by weight, preferably 0.15-2% by weight, and most preferably 0.2- 1 % by weight.

0101The compositions of the present invention may be used as formulations that are free of solvent, i.e. 100% solids, diluted with an organic solvent that is miscible, or as an aqueous emulsion. When the formulation of the present invention is used as a solventless coating, it is preferred that the viscosity of the alkenyl silicone be in a range varying from about 100 to about 10,000 centipoise, preferably from about 125 to about 1,000, more preferably from about 150 to about 500, and most preferably from about 200 to about 300 centipoise.' This is most easily accomplished by manipulation of the ratios of the stoichiometric subscripts between the terminal M and M^vl groups and the T groups in the formula:

0102Mvi_aT_bD_cM_d

0103with one general consideration being that a + d > b. If this condition is not met, the alkenyl silicone can become much more viscous. This does not preclude use of the silicone as a release coating material because the silicone may be dispersed or dissolved in a suitable solvent and coated thereby.

0104It is generally appregiated that other components may be added to the compositions of the present invention such as bath life extenders as taught in U. S. Patents 5,036,117 and 5,516,558; release additives for increasing the release force; fillers, extenders, reactive diluents, anchorage additives that improve adhesion to specific substrates, and the like. When used as emulsions, the silicones of the present invention are generally emulsified by the addition of non-ionic surfactants, addition of water followed by processing in a colloid mill.

0105All United States patents referenced herein are herewith and hereby specifically incorporated by reference.

EXPERIMENTAL

0107The following examples are designed to illustrate the present invention and are not to be construed as limiting the invention as embodied in these specific examples.

EXAMPLE 1

0109Preparation of anchorage additive:

0110A mixture of allyl glycidyl ether (AGE) (Aldrich, 2.886 g, 25.3 mmol) and polymethylhydrosiloxane (2.97 g, SiH = 47.5 mmol) was diluted with toluene (50 mL) and stirred with 0.61 x 10^"4 ppm platinum at room temperature. A small exothermic effect was observed after about 10 min. Progress of the reaction was followed by 1H NMR - after 1 hr 25% of Si-H groups were converted to Si-C bonds. In order to increase conversion of Si-H bonds, the mixture was stirred further for additional 24 hrs. Toluene was evaporated and the residue was characterized by NMR and GPC using CH₂C1₂ as an eluent (M„= 11100, M_w= 39100, M_w / M_n = 3.52). Purified product (5.4 g) was obtained with 95% yield. 1H NMR (CDC1₃): δ/ppm = 0.1 (s, OSi(CH₃)₃, terminal), 0.2 (s, -OSi(CH₃)O-), 0.5 (m, CH₂,), 1.65 (m, CH₂,), 2:6 and 2.8 ( , CH₂,) 3.1 (m, CH), 3.45 (m, CH₂,), 3.4 and 3.7 (m, CH₂,), 4.7 ( , SiH). ²⁹Si NMR (CDC1₃): δ/ppm = from -34 to -38 (-OSiMeHO-), -19 to -23 (-SiMe(CH₂)O-), 10 (-OSiMe₃).

0111Release coating with anchorage additive:

0112A release coating formulation prepared by mixing:

0113^]SL6626 5.0 g ¹SS4300c 0.16 g

0114Example 1 0.1 g

0115This coating formulation above was coated² onto 142 gauge polyester film (PET) corona treated to 54 dyne cm. Samples were cured for the times and the temperatures shown in Table 1 below. These were evaluated after 1 hour and 3 days room temperature aging for anchorage by a finger rub-off method.

0116¹ GE Silicones solventless paper release product

01172 Black Clawson Converting Machinery LC, Fulton, N.Y.

0118Table 1 - Abrasive test of PET films

0119<img file="WO2004071765A2_D0002.tif" />

0120Efficiency of attachment by "Rub-off was rated as follows:

0121very weakly attached

0122weakly attached

0123could be removed but not very easily + 1—

0124strongly attached -H-

0125very strongly attached

EXAMPLE 2

0127Preparation of anchorage additive:

0128A mixture of allyl glycidyl ether (AGE) (Aldrich, 142.7 g, 1.25. mol) and polymethylhydrosiloxane (150.0 g, SiH = 1.6 wt %) and 20 ppm rhodium using an ethanol solution of tris(dibutylsulfide)rhodium(III)trichloride containing 1.2 wt% rhodium at 120-130 °C after an exotherm to 170 °C for 4 hours. The reaction mixture was filtered then vacuum stripped at 120 °C to yield a 450 cstks reaction product having 0.52 wt% remaining SiH.

0129Release coating with anchorage additive:

0130A release coating formulation prepared by mixing:

0131'SL6625 500.0 g

0132'S_.Lόl lO-Dl 500.0 g

0133'8843000 23.0 g

0134Example 2 Additive 30.0 g

0135This coating formulation above were coated² onto 142 gauge polyester film (PET) corona treated to 54 dyne cm. Samples were cured for the times and the temperatures shown in Table 2 below. These were evaluated after 1 hour and 5 days room temperature aging for anchorage by a finger rub-off method.

0136¹ GE Silicones solventless paper release product

0137² Black Clawson Converting Machinery LLC, Fulton, N.Y. Table 2 - Abrasive Test of PET films

0138<img file="WO2004071765A2_D0003.tif" />

0139Efficiency of attachment by "rub-off was rated as follows:

0140very weakly attached

0141weakly attached

0142could be removed but not very easy + 1—

0143strongly attached ++ very strongly attached +++

EXAMPLE 3

0145Preparation of anchorage additives:

0146Additive A

0147A mixture of allyl glycidyl ether (AGE) (Aldrich, 79.1 g, 0.69 mol) and polydimethylmethylhydrosiloxane (200.0 g, SiH = 1.05 wt %) and 20 ppm rhodium using an ethanol solution of tris(dibutylsulfide)rhodium(III)-trichloride containing 1.2 wt% rhodium at 95-120 °C then held at 95-120 °C for 1 hour. The reaction mixture was vacuum stripped at 120 °C to yield a 199 cstks reaction product having 0.48 wt% remaining SiH.

0148Additive B

0149A mixture of allyl glycidyl ether (AGE) (Aldrich, 89.8 g, 0.79 mol) and polydimethylmethylhydrosiloxane (150.0 g, SiH = 1.05 wt %) and 20 ppm rhodium using an ethanol solution of tris(dibutylsulfide)rhodium(III)trichloride containing 1.2 wt% rhodium at 95-120 °C then held at 95-120 °C .forl hour. The reaction mixture was vacuum stripped at 120 °C to yield a 476 cstks reaction product having 0.24 wt% remaining SiH.

0150Additive C

0151A mixture of allyl glycidyl ether (AGE) (Aldrich, 66.2 g, 0.58 mol) and polymethylhydrosiloxane (145.0 g, SiH = .1.6 wt.%) and vinytrimethoxysilane (86.0 g, 0.58 mol) and 20 ppm rhodium using an ethanol solution of tris(dibutylsulfide)rhodium(III)trichloride containing 1.2 wt% rhodium at 95-145 °C then held at 95-110 °C for 2 hours. The reaction mixture yielded a 185 cstks reaction product having 0.38 wt% remaining SiH.

0152Release coating with anchorage additive:

0153A release coating formulation prepared by mixing: ¹SL6625 500.0 g

0154'SLόl lO-Dl 500.0 g

0155^{" 1}SS4300c , 23.0 g

0156Additive . 30.0 g

0157This coating formulation above were coated² onto 142 gauge polyester film (PET) corona treated to 54 dyne cm. Samples were cured for the times and the temperatures shown in Table 3 below. These were evaluated after 72 hours exposed to maximum humidity at 60 °C aging for anchorage by a finger rub-off method.

0158GE Silicones solventless paper release product

0159² Black Clawson Converting Machinery LLC, Fulton, N.Y. Table 3 - Abrasive Test of PET films

0160<img file="WO2004071765A2_D0004.tif" />

0161Efficiency of attachment by "rub-off was rated as follows:

0162very weakly attached

0163weakly attached

0164could be removed but not very easy + 1—

0165strongly attached ++

0166very strongly attached EXAMPLE 4 .

0167A mixture of carbic anhydride (13.1 g, 0.08 mol) and polymethylhydrosiloxane (100.0 g, SiH = 1.6 wt %) and 25 ppm platinum as Karstdet catalyst and 230.0 g toluene refluxed at 100-107 °C for 5 hours.^' The reaction mixture was vacuum stripped at 80 °C to yield a reaction product having 1.35 wt% remaining SiH with about 7 mole% carboxylic acid anhydride functionality.

0168Release coating with anchorage additive:

0169A release coating formulation prepared by mixing:

0170^]SL6625 500.0 g

0171'SLδllO-Dl 500.0 g

0172¹SS4300c 23.0 g

0173Additive 30.0 g

0174This coating formulation above were coated² onto 142 gauge polyester film (PET) corona treated to 54 dyne cm. Samples were cured for the times and the temperatures ^' shown in Table 3 below. These were evaluated after 72 hours exposed to maximum humidity at 60 °C aging for anchorage by a finger rub-off method.

0175¹ GE Silicones solventless paper release product

0176² Black Clawson Converting Machinery LLC, Fulton, N.Y. Table 4 - Abrasive Test of PET films

0177<img file="WO2004071765A2_D0005.tif" />

0178Efficiency of attachment by "rub-off was rated as follows:

0179very weakly attached

0180weakly attached

0181could be removed but not very easy + /-

0182Strongly attached

0183very strongly attached +++

COMPARISON EXAMPLE 1:

0185Comparison additive:

0186An anchorage additive prepared per U. S. patent 3,873,334 comprised of an epoxy functional silane and vinyltriacetoxysilane was evaluated at 1 and 3 wt. % as in Example 1 above. Rub-off was observed at both additive levels on non-adhesive and adhesive coated PET.

EXAMPLE 5

0188Example 2 additive evaluated in a UV cured release coating: Qualitative determinations of the effect of Example 2 additive on cure and anchorage of UV curable epoxysilicone coatings were completed using a Pilcher Hamilton 2 mil PET substrate. Two UV cure coating formulations were used in these experiments with the composition of Example 2 as candidate anchorage additive.

0189Composition A: lylixture of 90 parts ¹UV9400 epoxysilicone + 5 parts dodecylphenol + 5 parts 1HV9440E di-carbinόl stopped silicone fluid + 1.5 parts 1HV9385C iodonium photocatalyst solution.

0190Composition B: Mixture of 100 parts of dimethylepoxy-stopped linear D22.length silicone polymer + 2 parts ¹UV9380C sensitized iodonium photocatalyst solution.

0191Coatings ~ 1.2 g/m². weight were manually applied to 2 mil PET substrates, then exposed to focused UV light from Hanovia medium pressure mercury vapor lamps mounted in an RPC Model lab UV Processor. Samples were affixed to a carrier board and passed under the lamps on a conveyer. Total UV flux directed at the coatings was modulated by varying lamp power and conveyer speed to furnish either ~ 65 mJ/cm²

0192' ? I ^■ or ~ 160 mJ/cm UV flux. Coatings were examined for silicone migration to Scotch™ 610 cellophane adhesive tape and for smear and rub-off (tendency of a coating to be readily removed from a substrate by light finger pressure or rub).

0193Results and observations are given in Table 5 below.

0194¹ GE Silicones solventless paper release product Table 5

0195Example 2 additive is incompletely miscible with compositions A &amp; B, but fomied stable cloudy mixtures when 3 parts were blended with 100 parts of coating.

0196Qualitative results are tabulated below:

0197<img file="WO2004071765A2_D0006.tif" />