EP0309557A1

EP0309557A1 - Improved release coatings

Info

Publication number: EP0309557A1
Application number: EP88903727A
Authority: EP
Inventors: Frank Puskadi; Frank J. Welch; Michael E. Story; Kenneth S. C. Lin; William D. Kray; Douglas Wayne Wilson
Original assignee: Avery International Corp
Current assignee: Avery Dennison Corp
Priority date: 1987-04-09
Filing date: 1988-04-01
Publication date: 1989-04-05
Also published as: BR8806894A; KR890700470A; JPH01503544A; AU1594388A; EP0309557A4; FI885706A0; FI885706A; WO1988007931A1

Abstract

D'excellentes surfaces de libération sont réalisées par polymérisation d'une composition matérialisée par une dispersion d'une silicone réactive, présente dans une quantité allant de 1 à 30% en poids de la composition, à titre de phase discontinue dans une phase continue d'une résine réactive, comprenant un oligomère réactif et facultativement un monomère réactif. Le produit a une surface de libération en silicone ayant de la silicone ancrée dans la couche. La surface est conçue pour entrer en contact avec un adhésif sensible à la pression et s'en détacher. On peut avoir recours à la chaleur, à un faisceau d'électrons et/ou des rayonnements utlraviolets pour réaliser la polymérisation.Excellent release surfaces are produced by polymerization of a composition materialized by a dispersion of a reactive silicone, present in an amount ranging from 1 to 30% by weight of the composition, as a discontinuous phase in a continuous phase d a reactive resin, comprising a reactive oligomer and optionally a reactive monomer. The product has a silicone release surface having silicone anchored in the layer. The surface is designed to contact and detach from a pressure sensitive adhesive. Heat, an electron beam and / or ultraviolet radiation can be used to carry out the polymerization.

Description

IMPROVED RELEASE COATINGS

Background of the Invention

The construction of pressure sensitive adhesive products presents a variety of materials selection problems. Basic to any construction is the selection of a suitable release surface.

A label, for instance, is normally comprised of a face stock which may range from paper to a plastic film such as polyester film or even metal; a release liner having a silicone release surface, and a pressure-sensitive adhesive layer, normally rubber or acrylic based in contact with the face stock and the silicone release surface. In self-wound products, a silicone release may be applied to the face stock opposite the side to which the adhesive is applied. Conventional silicone release coatings are essentially

100% by weight as a silicone resin on a solids basis and by weight the most expensive raw material in label and tape constructions. It would be desirable to reduce the amount of silicone employed as this would reduce the cost of the silicone release surface. Reducing silicone content, however, has a normal effect of increasing the bond to the release surface. As dilution occurs a point is reached where the bond becomes so great that the adhesive may sever the silicone material from the substrate, normally paper, to which it was applied and in effect transfer the silicone to the adhesive to the de ment of the ability to bond the adhesive to another su ce.

U.S. Patent 4,288,479 to Brack is directed to release coatings which contain a waxy material of limited compatibility with a liquid monomer or prepolymer. Upo application to a film, the waxy material migrates to the surface. Radiation is applied to cure the polymer. The waxy material which include silicones are described as generally non-reactive in the polymerizable liquid but can contain reactive groups. In Example 65 of the Brack patent, there is described a release composition containing a silicone rubber which was a polydimethyl siloxane with some unsaturation. On radiation there was stated to be formed a surface releasable with respect to a removable adhesive. We have found that the composition is not functional for permanent pressure sensitives which differ from removable adhesives in that adhesive bond grows with time. As established here, the combination welded together. See Example 5 herein.

The present invention is directed to novel formulations of substantially reduced silicone content which display excellent release properties.

Summary of the Invention

There is provided a substrate having bonded thereto a cured release coating having a silicone release surface for contact with a pressure-sensitive adhesive formed by coreaction of components of a coating composition of a silicone comprised of dimethyl siloxane polymers, preferably a reactive silicone and a resin preferably a reactive resin. The silicone is present in an amount of from about 1 to about 30 percent by weight of the coating composition and anchored to the coating so as to be substantially non-transferable to a pressure-sensitive adhesive. The silicone release surface is functional to release permanent and removable pressure-sensitive adhesive .

Cure is preferably induced by the action of heat, actinic radiation and/or electron beam radiation, provided in a quantity sufficient to anchor the silicone to the resin whereby the silicone becomes substantially non-transferable to a pressure-sensitive adhesive. Ultraviolet and/or electron beam radiation is presently preferred. The silicones employed preferably have a molecular weight of at least about 2,000, preferably 10,000 or more.

It is presently preferred that the products be formed by curing a coating comprised of from about 1 to about 30 percent by weight, preferably from about 5 to about 30, most preferably from about 5 to about 15 percent by weight, of a reactive silicone dispersed as a discontinuous phase in a reactive resin present in an amount of from about 99 to about 70 percent by weight, preferably from about 95 to about 70 percent by weight, more preferably from about 95 to about 85 percent by weight, of the combination of the reactive silicone and reactive resin. The reactive resin contains from about 50 to 100 percent by weight reactive oligomer and from about 50 to 0 percent by weight reactive monomer based as the total weight of reactive oligomer and reactive monomer. The reactive monomer is used to control viscosity prior to cure.

To enable good coatability, the dispersion preferably has a viscosity of from about 300 to about 10,000 cps. There may also be included in the system as required photoinitiators, colorants and the like.

The invention enables tailoring of the silicone release surface to the product. Useful products will have TLMI (Tape and Label Manufacturers Institute) peel under Keil conditions of no greater than about 400 N/M. For tapes the TLMI peel should be no greater than about 400 N/M, more typically 100 to 200 N/M. For tags and labels a "high release specification has a peel up to about 60 to about 100 N/M; a "medium" release has a TLMI peel of about 20 to about 50 N/M; and a "low release" has a TLMI peel of less than about 20. Again all peel values are reported for Keil conditions, namely after aging at a load of 0.25 psi for 20 hours at 70ºC.

Brief Description of the Drawings

FIG. 1 illustrates Carver release in grams per inch as a function of aging at room temperature for the composition described in Example 1. FIG. 2, the Carver release is for the same composition except for aging at 140ºF.

FIG. 3 illustrates the release as a function of silicone content of the coating at the time of cure.

FIG. 4 illustrates the same release but after aging for 28 days at room temperature.

FIG. 5 is for the same composition but after aging 28 days at 140ºF.

FIG. 6 shows the effect of concentrations of photo initiator on the release force and its effect with time. Attached drawing marked "Prior Art" depicts the accepted effect on a control release additive on a silicone release material. As can be appreciated by inspection, the release force remains fairly constant until some point is reached where the force increases dramatically. On the scale, zero designates no control release additive while 1 designates no silicone polymer.

Detailed Description

There is provided in accordance with the present invention a substrate having thereon a cured coating of silicone release surface for contact with a pressure-sensitive adhesive. The coating is formed by coreaction of a silicone comprised of dimethyl siloxane polymers, preferably a reactive silicone and a resin, preferably a reactive resin comprising a reactive oligomer. Under curing conditions induced by application of sufficient heat, electron beam (EB) radiation and/or actinic radiation, preferably ultraviolet (UV) radiation, the silicone is anchored to the cured coating and is rendered substantially non-transferable to a pressure-sensitive adhesive in contact with the release surface. The dimethyl siloxane polymer content of the coating is from about 1 to about 30 percent by weight on the total weight of the constituents of the coating with the anchored silicone preferentially concentrated at the surface provided for contact with a pressure-sensitive adhesive. The cured coating may be achieved using silicone-monomer combinationso

Preferential presence of silicone at the surface may be achieved by partial to total incompatibility of the silicone and the resin, or by structural rearrangement of a silicone-resin surface. What is critical is that the silicone is sufficiently anchored to the surface and substantially non-transferable to a pressure-sensitive adhesive. Anchoring may be mechanical and/or chemical.

The desired products have a Carver release as defined herein of less than about 100 grams per inch. Carver release is determined by applying Scotch™ 610 tape to the release surface under a pressure of 6000 psi for 60 seconds then measuring force required to achieve release at a peel rate of 12 inches per minute. As used herein, by the term "silicone" there is meant dimethyl siloxane polymers consisting of alternate silicone and oxygen atoms with methyl groups attached to silicon The general structure is: CH₃ CH₃ CH₃

OSi O Si OSi CH₃ CH₃ x CH₃ wherein "x" is an integer.

By the term "reactive silicone" there is meant a silicone end capped and/or mid-chain substituted with groups reactive on application of heat and/or energy with reactive groups of the resin. The presently preferred reactive groups are acrylic, mercapto and/or oxirane.

By the term "resin" there is meant an organic moiety which is combinable with the silicone and reactive with silicone and/or reactive silicone under action of heat, actinic radiation and/or electron beam radiation to cause anchoring, preferably preferential surface anchoring of the silicone to the resin. By the term "reactive resin" there is meant a resin comprising reactive oligomers containing groups which are reactive with the reactive groups of a reactive silicone. The presently 'preferred reactive oligomers contain reactive acrylic, mercapto and/or oxirane groups. The reactive resin may include a reactive monomer used to control viscosity, although not necessary to utility of the silicones.

By the term "reactive monomer" there is meant monomers which coreact with the reactive silicone and/or the reactive oligomer of the reactive resin and which are effective in reducing viscosity of coating composition used to form the end products of this invention. It is preferred that the reactive monomer be a multifunctional monomer preferably a multifunctional acrylate. By the term "silicone release surface" there is meant a surface which will release from a pressure sensitive adhesive substantially without transfer of release material to the adhesive and having a TLMI peel under Keil conditions of no greater than about 400 N/M.

It is presently preferred that the products of the invention be formed by coating a substrate such as paper then curing the coating, where the coating is comprised of from about 1 to about 30 percent by weight, preferably about 5 to about 30 percent by weight, more preferably about 5 to about 15 percent by weight, of a reactive silicone dispersed as a discontinuous phase in a reactive resin present in an amount of from about 99 to about 70 percent by weight, preferably from about 95 to about 70 percent by weight, more preferably from about 95 to about 85 percent by weight of the combination of the reactive silicone and reactive resin. The reactive resin contains from about 50 to 100 percent by weight reactive oligomer and from about 50 to 0 percent by weight reactive monomer based as the total weight of reactive oligomer and reactive monomer. The reactive monomer is used to control viscosity prior to cure. There may also be included in the system as required photoinitiators, colorants and the like. To enable good coatability, the dispersion should have a viscosity of from 300 to about 10,000 cps. Viscosity can, as indicated, be adjusted by the addition of reactive monomers.

While not bound by theory, it is presently believed that surface reorientation occurs to form the silicone release surface. Reorientation can occur either prior to, during or following cure, as it has been observed, the quality of release of the silicone release surface can increase with time, even a fairly short time span, and then level out. Improved release is attributed to the amount of silicone at the surface. The cured coating is believed similar to block or graft copolymers having oligomer blocks bound to the silicone blocks with preferential presence of silicone at the surface as opposed to the body of the coating. The coating typically has a glass transition temperature of at least 0°C, preferably greater than about 20°C.

Critical to the use of a dispersion is that the proportion of reactive silicone and reactive resin remain as a coatable dispersion in which the reactive silicone is as the dispersed phase and the reactive resin is the continuous phase. Once a certain level of reactive silicone monomer content is reached, phase inversion begins, to the end of forming a system in which the reactive resin is the dispersed phase and the reactive silicone is the continuous phase. When this is complete, the cured product will become rubbery and behave like a conventional silicone release coating which requires a high concentration of silicone before a suitable release level is achieved.

In the practice of the invention, the dispersion is coated in a conventional manner onto a substrate which may be any grade of paper, including the papers of low grade, cardboard, polymeric films and the like. Cure is to be sufficiently complete, such that substantially no silicone transfers to a pressure-sensitive adhesive to which the silicone release surface contacts. Avoidance of transfer is the result of the silicone being anchored to coating body and not available to transfer to the pressure-sensitive adhesive.

Electron beam cure has a particular benefit, since it can initiate reaction of resins with substantially non-reactive silicones to produce a functional release surface. The ability of the coating to accept colorants is a desirable feature for establishing the presence and uniformity of the release coating.

What is produced by the practice of the invention is a unique product of low silicone content but having a silicone release surface having excellent release properties. The coating is hard and substantially non-stretchable and aggressively bound to the substrate to which it is applied. Substantially complete cure insures against transfer to the adhesive during the lifetime of a laminate or self-wound product. The release coatings of this invention provides the advantage that the release force can be relatively constant over broad range of stripping speeds without the silicone substantially transferring to the adhesive surface. High holdout can be achieved on low grade papers and monomers can be used not only to adjust viscosity but also adjust release force.

In the following Examples TLMI Release is by Test Method VII LD-468 and PSTC Test No. 2. Loop Tack is by PSTC - Test No. 5. Keil release values are after aging under a force of 0.25 psi for 20 hours at 70ºC. TLMI means Tape and Label Manufacturers Institute and PSTC means Pressure Sensitive Tape Council. Except for the removable adhesive identified as part of Example 1, the adhesives employed in the Examples were permanent rubber based and/or acrylic based pressure-sensitive adhesives.

EXAMPLE 1 (FIGS. 1-6)

A master batch of a resin coating designated as AE- 508 was formed of 72 parts by weight acrylated epoxy oligomer (Celanese 3703) supplied by Celanese Corp., 16 parts by weight hexanedioldiacrylate (HDODA) and 12 parts by weight diethoxyacetophenone (DEAP). From 80-95 parts of the master batch was mixed with 20-5 parts

Dehesive™ VP-1530, a mixture acrylated and thiol and functional polysiloxanes, available from Stauffer-Wacker Silicones Co. (S-1530 herein). The mixtures were prepared in select increments of weight percent silicone.

The coating mixtures were applied on clay coated gloss paper. The coated paper was exposed to the UV radiation given off by two medium pressure mercury vapor lamps at 200 watts/inch at web speed of 50 feet per minute. This corresponds to an energy input of about 5 kilojoules per square meter. Exposure resulted in cure to a hard glossy film which was dry to the touch. Completeness of cure was determined by laminating Scotch™ 610 tape manufactured by 3M, under pressure and measuring the force required to delaminate the construction or remove the tape. Release which is stable and low over time without substantially detackifying the adhesive is one indication of complete cure.

Cured coatings with varying amounts of S-1530 were tested using the Carver release test which consists of laminating the cured release liner to Scotch™ 610 tape under a pressure of 6,000 psi for 60 seconds, and measuring force required to achieve release at a peel rate of 12 inches per minute (ipm). Release measurements were modified to include a 1200 inches per minute (ipm) rate. The release test as applied to aged samples was after aging with the test tape applied just before measuring release values.

The initial formulation consisted of 90% AE 508 and

10% S-1530. As shown in FIGS. 1 and 2, the initial

Carver Release values were between 80-100 grams. Aging at room temperature or 140°F, resulted in a rapid decline to a stable release level within the range of 20-50 grams.

FIGS. 3, 4 and 5 show the results of varying the concentration of S-1530 on Initial Peel (FIG. 3) after room temperature (RT) aging (FIG. 4) and elevated temperature aging (FIG. 5). The results display a phenomenon that appears to be related to phase transition. As silicone content increases there is reached a point where a transition to a rubbery phase occurs. The system then behaves in a conventional way, with release force decreasing with an increase in silicone content.

More particularly, FIG. 3 shows the initial Carver Release results and shows low initial releases (both 12 and 1200 ipm) in the range of 3%-5% S-1530. In the range of 10%-40% S-1530 initial release values increase, with 1200 ipm releases actually appearing to be lower than 12 ipm. By 40%, S-1530 12 ipm release values decline while 1200 ipm releases increase rapidly and appear to level off above 50% S-1530.

FIGS. 4 and 5 show the Carver release values for samples aged 28 days at RT and 140°F. Formulations in the 5%-20% S-1530 range yield release values in the range of 20-40 grams with minimal differences between 12 and 120θ ipm releases. Above about 30% S-1530, the release values climb rapidly, peak, and then decline as the percentage of S-1530 increases beyond 40%. The range beyond 60% S-1530 is again characterized by a marked difference between 12 and 1200 ipm release values. The region up to 20 percent is hard and glassy with desirable release values. Above about 30% S-1530 a phase inversion occurs to a rubbery phase which is characteristic of conventional release liners.

The concentration of photoinitiator diethyl acetophenone (DEAP) in the formulation has a significant effect on the initial Carver release values of lab samples. As shown in FIG. 6, the formulation with an excessive amount of DEAP (20%) yields initially high Carver release values, which subsequently age down to a level similar to formulations with 1%-5% DEAP. This is similar to the aging down observed in FIGS. 1 and 2 are for formulations having a concentration of 10.8% DEAP. Constructions using a rubber based hot melt removable adhesive and a high tack, high peel rubber based hot melt adhesive, were made and found to have acceptable low release from the surface to 10% S-1530. Constructions using 4, 6 and 10% S-1530 were prepared using a removable adhesive. Formulations using 6 and 10% S-1530 had low release whereas the formulation using 4% silicone had tighter release as measured by subjective testing.

EXAMPLE 2

There was evaluated the performance of AE-508 with various reactive silicones as against their performance as homopolymers. The control was a standard thermally cured silicone release liner. The reactive silicones were S-450, an end acrylated silicone known as RC-450 supplied by Goldsmith Chemical Corporation; S-1559, a mixture of acrylated and mercapto functional silicone known as Dehesive™ VP-1559 supplied by Stauffer Wacker-Silicone Corp.; S-4818, an end and in chain acrylated silicone known as IC-4818-38 supplied by Lord Chemical Company and S-5360 and S-6350, each end and in chain acrylated silicones known respectively as Ebecryl 19- 6360 and 19-6350, supplied by U.C.B. Radcure Inc.

Table 1 shows performance with an acrylic adhesive while Table 2 shows performance with a rubber based adhesive. In the Table, homopolymer means 100% of the reactive silicone; copolymer means 80% by weight AE-508 and 20% by weight reactive silicone. In each instance the coating was formed on a super calendered kraft paper and EB cured at a dosage of 30 kGy.

The conclusion drawn was that the copolymers served as useful release agents as did the most costly homopolymers. TABLE 1

TLMl Beel

300 ipm(N/M) Loop Tack (N/M)

Homopolymer 3 Day Keil 3 Day

S-450 69 54 450

S-1559 22 44 340

S-4818 18 40 405

S-6360 134¹ 138¹ 335

S-6350 119 168 130

Copolymer

S-450 64¹ 362 165

S-1559 36 28² 455

S-4818 30^1,2 37² 445

S-6360 60^1,2 46¹'² 515

S-6350 87^1,2 111² 515

Control 6 6 400

X Release Pickoff at Slow Speeds 2 Zippy Release

TABLE 2

TLMl Peel

300 ipm(N/M) Loop Tack (N/M)

Homopolymer 3 Day Keil 3 Day Keil

S-450 4 7 1895 1980

S-1559 5 8 1615 1655

S-4818 3 5 1575 1715

S-6360 5 22² 1720 1850

S-6350 8 12² 1065 1280

Copolymer

S-450 7 10 1870 1835

S-1559 6 5 1790 1655

S-4818 4 4 1770 1495

S-6360 26² 39¹ 1990 1750

S-6350 14² 20² 1950 1695

Control 4 6 1625 1590

1 Release Pickoff at Slow Speeds 2 Zippy Release EXAMPLE 3 The following is to show the effect of using the different oligomer and monomer combinations to enable control of release. With reference to Table 2, resins 19-6810, 19-6830 and 19-6657 are acrylated polyesters sold by U.C.B. Radcure, Inc.; PES-166 and PES-169 are acrylated urethanes sold by Polymer Systems Corporation; "BPA diacryl" is an acrylated bisphenol-A epoxy resin; C-9003 is an aliphatic triacrylate. The control was a commercial release liner having a 100% silicone surface. The adhesive employed was a tackified Kraton-1107, a styrene-isoprene, styrene-isoprene-styrene resin rubber manufactured and sold by Shell Chemical Company. The formulation in each instance was 70% by weight resin or monomers, 20% by weight hexanedioldiacrylate (HDODA) and 10% by weight S-1559. Cure was by electron beam at a dosage of 30 kGy in the presence of 200-250 ppm oxygen. Results shown in Table 3 established that epoxy, urethane and polyester oligomers gave low release values whereas an aliphatic oligomer gave higher release.

TABLE 3

Resin Description TLMI : RELEASE (N/M) LOOP TACK (N/M)

One Day Keil One Day Keil

19-6810 Polyester 7 14 590 630

19-6830 Polyester 34 26 980 690

19-6657 Polyester 19 22 690 710

PES-166 Urethane 1 10 690 710

PES-169 Urethane 8 11 670 650

SR-349 BPA Diacryl 1 19 690 590

C-9003 Aliphatic Triac 75 88 590 530

Control -- -- 850 650 EXAMPLE 4 In Example 65 of U.S. Patent 4,228,479 to Brack, there is disclosed a potential formulation for a release surface. The formulation was prepared with certain substitutions made because of the lack of availability of components. The substitutions were not believed to modify the performance as the controlling ingredient was the silicone employed. The base formulations are shown in Table 4.

TABLE 4

COMPONENTS

EXAMPLE.65 FORMULATION A

66 Parts Trifunctional Urethane PES-166 DifunctionalUrethane

68 Parts 1,4-Butane Diol Diacrylate 1,6 Hexane Diol Diacrylate 50 Parts Acrylated Epoxidized Soya Oil same

72 Parts Trimethylolprop. Tri Aery same

1.5 Parts 2-Hydroxy Ethyl Acrylate 1,4-Butane Diol Monoacrylate

2 Parts Stearyl Acrylate same

5 Parts W-982 Silicone Gum (0.2% vinyl) Several Variations

16 Parts Benzoin Isobutyl Ether Benzoin Isopropyl Ether

Since Brack taught the use of a silicone of low functionality there was employed as a representative of the silicone contemplated by the patentee, 0.2% VOC, which was a 0.2% vinyl end capped polydimethyl siloxane. Their performance with respect to a hot melt rubber base adhesive and an acrylic adhesive are formulations A to B of Tables 5 and 6. UV cured formulations as suggested by Brack were regarded as nonfunctional as a release surface as the Keil values for the loop tack could not even be measured due to welding. It was surprisingly found that high energy dosage available by electron beam cure could produce functional release materials. When formulation A was used with the silicones of the instant invention, namely formulations C and D, they as well as formulations E to H at all times a functional release surface formed under both UV and EB conditions. In the process, a master batch of all components except the silicone formulation was prepared. The various formulations were prepared by taking a portion of the master batch and adding the silicone and photo-initiators as required. Samples were coated on super-calendared kraft paper and cured by either UV or EB radiation. The cured samples were then laminated to freshly prepared dry adhesives on polyester films. They were aged for one day under Keil conditions (70 °C, 0.25 psi for 20 hours) and TLMI release measured at 300 inches per minute; the results including loop tack data measured are reported in Tables 5 (rubber based permanent adhesive) and 6 (acrylic based permanent adhesive) .

TABLE 5

Form Resin Silicone SI% Cure TLMl Release(N/M) Loop Tack(N/M)

One 1 Day Keil One Day Keil

A A 0.2% VEC+BIPE 1.8 UV 40 WELD 1340 --

B A 0.2% VEC+BIPE 10 UV 35 WELD 700 --

C A S-1559 1.8 EB 7 32 1880 1830

D A S-1559 10 EB 7 24 1450 1720

E AE-508 S-1559+BIPE 10 UV 2 1 1000 900

F AE-508 S-1559+12BIPE 10 UV 2 1 1240 920

G AE-508 S-1559+12DEAP 10 UV 35 5 1140 1150

H AE-508 S-1559 10 EB 6 12 1635 1700

Control 100 -- 3 8 1700 1750

Form = Formulation TABLE 6

Form Resin Silicone SI% Cure TLMI Release(N/M) LoopTack(N/M)

One Day Keil One Day Keil

A A 0.2% VEC+BIPE 1.8 UV 140 WELD -- --

B A 0.2% VEC+BIPE 10 UV 160 WEID -- --

C A S-1559 1.8 EB 110 93 420 520

D A S-1559 10 EB 100 30 370 340

E AE-508 S-1559+BIPE 10 UV 30 55 300 220

F AE-508 S-1559+12BIPE 10 UV 25 50 -- 300

G AE-508 S-1559+12DEAP 10 UV 55 67 -- 160

H AE-508 S-1559 10 EB 70 100 420 550

Control 100 -- 100 150 400 220

Cure Dose: ΕB=30KGy;UV=2x200Watts/Inch Lamps, 50 ft/min.

VP-1559 Radiation Curable Silicone Coating from SWS Silicones

0.2% VEC = 0.2% Vinyl Encapped Polydimethylsiloxane

BIPE=6% Benzoin Isopropyl Ether, 12BIPE=12% Benzoin Isopropyl Ether

12DEAP=12% Diethoxyacetophenone

Form = Formulation

EXAMPLE 5 Formulation AE-508 was as a base formulation employing GE 479-1866 an experimental epoxy functional silicone provided by General Electric Company, Silicone Products Division. The formulations are shown in Table 7 and Carver release results reported after UV cure using 2 lamps at 200 watts per inch at a web speed of 50 feet per minute are shown in Table 8. Results are high average or highest value.

TABLE 7

Formulation. Percent By Weight A B C

AE-508 95 94 89

GE 479-1866 5 5 10

Additional Photoinitiator 0 1 1 TABLE 8

Carver Peel in grams/inch at Formulation

A B C

I. 12 ipm at

R.T., initial 55 7 (a) 7 days 13 10 3 14 days 11 - - 28 days 7 4 3

140ºF 7 days 13 12 8 14 days 24 20 4 28 days 13 7 4

II. 1200 ipm at R.T., initial 195 65 62 7 days 48 54 68 14 days 54 60 77 28 days 54 61 64

140°F - 7 days 45 48 53 14 days 57 60 71 28 days 48 52 42

(a) Too low to measure

EXAMPLE 6 Tests were conducted to show the effect of using the different oligomers and silicone combinations to enable control of release. With reference to Table 9, resin Valspar™ S-9783-002 a mixture of acrylated oligomers provided by Valspar Co. was mixed with S-450 in varying amounts coated and EB cured (30kGy) on a polypropylene release backing. Peel was measured with respect to a permanent rubber based pressure sensitive adhesive.

TABLE 9

KEIL % S-450 % OLIGOMER RELEASE (N/M) 180° PEEL (N/M) 5 95 300 460 10 90 170 440 15 85 120 440 EXAMPLE 7 The data of Table 10 shows the effect of using the different monomer combinations on release. The monomers were pentaarythritoltriacrylate (PETA), hexanedioldiacrylate (HDODA) and 2-ethylhexyl acrylate (2EHA).

TABLE 10

KEEL

RELEASE LOOP TACK % S-450 % 2-EHA % PETA % HDODA (N/M) (N/M) 25 - - 75 80 600 25 25 25 25 9 650 25 - 25 50 170 400

EXAMPLE 8 A mixture of 20 parts trimethylopropanetriacrylate,

40 parts Celrad 3201, an acrylated polyester from Celanese, Inc., 10 parts N-vinylpyrrolidone and 1.5 parts S-6350 and 2 parts photo initiator was coated onto crepe paper and cured with enough actinic (UV) radiation to give a hard dry film. The release liner was Keil aged against a permanent rubber based pressure sensitive adhesive. The Keil release forces were 80-150 N/M with minimal loss of adhesive tack.

Claims

WHAT IS CLAIMED IS:

1. A product comprising a substrate having bonded thereto a cured release coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive said coating formed by coreaction of a silicone comprised of dimethyl siloxane polymers and a resin contained in a coating composition applied to the substrate, the silicone being present in an amount of from about 1 to about 30 percent by weight of the coating and sufficiently anchored to the coating to be substantially non-transferable to a pressure-sensitive adhesive.

2. A product as claimed in claim 1 in which the silicone is present in an amount of from 5 to about 15 percent by weight of the coating.

3. A product comprising substrate having bonded thereto a cured release coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive said coating formed by coreaction of silicone present in an amount of from about 1 to about 30 percent by weight of the coating and a resin contained in a coating composition applied to the substrate, the cure induced by exposure of the applied coating to the action of energy supplied by heat, actinic radiation, electron beam radiation, or combinations thereof induced in a sufficient amount to anchor the silicone to the coating whereby the silicone is substantially non-transferable to a pressure-sensitive adhesive.

4. A product as claimed in claim 3 in which the silicone is present in an amount of from about 5 to about 15 percent by weight of the coating.

5. A product comprising a substrate having bonded thereto a cured release coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive and said coating formed by coreaction of a reactive silicone present in an amount of from about 1 to about 30 percent by weight of the coating and a reactive resin comprised of reactive oligomers contained in a coating composition applied to the substrate, the cure induced by the action of energy supplied by heat, actinic radiation, electron beam radiation, or a combination thereof and induced in an amount sufficient to anchor the silicone to the coating whereby the silicone is substantially non-transferable to a pressure-sensitive adhesive.

6. A product as claimed in claim 5 in which the silicone is present in an amount of from about 5 to about 15 percent by weight of the coating.

7. A product comprising a substrate having bonded thereto a cured release coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive and said coating formed by coreaction of a reactive silicone present in an amount of from about 1 to about 30 percent by weight of the coating and a resin comprised of reactive oligomers, said reactive silicone being at least partially immiscible in said coating composition, the cure induced by the action of energy supplied by heat, actinic radiation, electron beam radiation, or a combination thereof induced to the coated substrate in sufficient amount to anchor the silicone to the coating whereby the silicone is substantially non-transferable to a pressure-sensitive adhesive.

8. A product as claimed in claim 7 in which the silicone is present in an amount of from about 5 to about 15 percent by weight of the coating.

9. A product as claimed in claim 1 which includes a colorant.

10. A product as claimed in claim 7 which includes a colorant.

11. A product comprising a substrate having coating on at least one side thereof with a cured coating composition comprised of from about 1 to about 30 percent by weight of the coating composition of a reactive silicone dispersed as a discontinuous phase in about 99 to about 70 percent by weight of the coating composition or continuous reactive resin phase comprising from about 50 to 100 percent by weight of the oligomer reactive with said reactive silicone and from about 50 to 0 percent by weight of the reactive resin of a reactive monomer, said reactive silicone being a polydimethyl siloxane having a molecular weight of at least about 2000 and having pendent therefrom sufficient reactive groups to react with the reactive groups of the oligomer, said coating being cured on exposure to the action of electron beam radiation, ultraviolet radiation, heat or a combination thereof to form cured coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive with substantially all of the silicone contained in the coating composition being anchored to the cured coating and substantially non-transferable to a pressure-sensitive adhesive.

12. A product as claimed in claim 11 in which the reactive silicone is present in an amount of from about 5 to about 15 percent by weight of the coating composition.

13. A product as claimed in claim 11 in which the oligomers are selected from the group consisting of acrylated epoxies, acrylated polyesters, acrylated polyurethanes and mixtures thereof.

14. A product as claimed in claim 11 in which the reactive monomer is a multifunctional monomer.

15. A product as claimed in claim 12 in which the reactive monomer is a multifunctional monomer.

16. A product as claimed in claim 15 in which the reactive silicone is present in an amount of from about 5 to about 15 percent by weight of the coating composition.

17. A product as claimed in claim 11 in which the reactive groups of the silicone are selected from the group consisting of acrylic groups and mercaptos groups, oxiranes and mixtures thereof.

18. A product as claimed in claim 12 in which the reactive groups of the silicone are selected from the group consisting of acrylic groups, mercapto groups, oxiranes and mixtures thereof.

19. A product as claimed in claim 16 in which the reactive groups of the silicone are selected from the group consisting of acrylic groups, mercapto groups, oxiranes and mixtures thereof.

20. A curable coating composition comprising from about 1 to about 30 percent by weight of the coating composition of a reactive silicone dispersed as a discontinuous phase in 99 to 70 percent by weight of the coating composition of reactive resin phase comprising:

(i) from 50 to 100 percent by weight of the reactive resin of an oligomer reactive with said reactive silicone and

(ii) from about 50 to 0 percent by weight of the reactive resin of a reactive monomer, said reactive silicone being a polydimethyl siloxane having a molecular weight of at least about 2000 and having pendent therefrom sufficient reactive groups to react with the reactive group of the oligomer on exposure to the action of electron beam radiation, ultraviolet radiation or heat to form a cured coating having a silicone release surface releasable from a pressure-sensitive adhesive and in which substantially all of the silicone contained in the composition is anchored to the coating to substantially prevent transfer of the coating to a pressure-sensitive adhesive.

21. A curable composition as claimed in claim 20 in which the reactive silicone is present in an amount of from about 5 to about 15 percent by weight of the coating composition.

22. A curable coating as claimed in claim 20 in which the oligomers are selected from the group consisting of acrylated epoxies, acrylated polyesters, acrylated polyurethanes and mixtures thereof.

23. A curable coating as claimed in claim 20 in which the reactive monomer is a multifunctional monomer.

24. A curable coating as claimed in claim 22 in which the reactive monomer is a multifunctional monomer.

25. A curable composition as claimed in claim 24 in which the reactive silicone is present in an amount of from about 5 to about 15 percent by weight of the coating composition.

26. A curable coating as claimed in claim 20 in which the reactive groups of the silicone are selected from the groups consisting of acrylic groups, mercapto groups, oxirane groups and mixtures thereof.

27. A curable coating as claimed in claim 21 in which the reactive groups of the silicone are selected from the groups consisting of acrylic groups, mercapto groups, oxirane groups and mixtures thereof.

28. A curable coating as claimed in claim 25 in which the reactive groups of the silicone are selected from the groups consisting of acrylic groups, mercapto groups, oxirane groups and mixtures thereof.

29. A curable coating composition comprising: (a) from about 5 to about 15 percent by weight of the coating composition of a reactive silicone having reactive groups selected from acrylic groups, mercapto groups, oxirane groups and mixtures thereof, dispersed as discontinuous phase in a from 95 to about 85 percent by weight of the coating composition of a continuous reactive resin phase comprising:

(i) from about 50 to 100 percent by weight of the reactive resin of an oligomer reactive with said reactive silicone and selected from the group consisting of acrylated epoxy resins, acrylated polyester resins, acrylated urethane resins and mixtures thereof, and

(ii) from 50 to about 0 percent by weight of the reactive resin of at least one acrylated multifunctional monomer, said reactive silicone being a polydimethylsiloxane having a molecular weight of at least about 2,000, said composition having a viscosity of from about 300 to about 10,000 centipoise and curable on exposure to the action of electron beam radiation, ultra-violet radiation or heat, or a combination thereof, to form a cured coating having a silicone release surface opposed the substrate to which the coating has been applied for releasable contact with a pressure-sensitive adhesive and in which substantially all of the silicone contained in the composition is anchored in the coating and substantially nontransferable to a pressure-sensitive adhesive.

30. A process for producing a release coated substrate which comprises:

(a) applying to a substrate a coating composition comprising:

(i) from about 1 to about 30 percent by weight of the composition of a reactive silicone dispersed as a discontinuous phase in from about 99 to about 70 percent by weight of the coating composition of a continuous reactive resin phase comprising:

(ii) from about 50 to 100 percent by weight of reactive resin phase of an oligomer reactive with said reactive silicone, and

(iii) from about 50 to 0 percent by weight of the reactive resin phase of a reactive monomer, said reactive silicone being a polydimethylsiloxane having a molecular weight of at least about 2,000 and having pendent therefrom sufficient reactive groups to react with the reactive groups of the oligomer;

(b) exposing the coating to the action of sufficient electron beam radiation, ultraviolet radiation or heat or a combination thereof to form a cured coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive and in which substantially all of the silicone groups are anchored in the cured coating and substantially non-transferable to a pressure-sensitive adhesive.

31. A process as claimed in claim 30 in which coating composition has a viscosity of from about 300 to about 10,000 centipoise.

32. A process as claimed in claim 30 in which the oligomers are selected from the group consisting of acrylated epoxies, acrylated polyesters, and acrylated polyurethanes and mixtures thereof.

33. A process as claimed in claim 30 in which the reactive monomer is a multifunctional monomer.

34. A process as claimed in claim 32 in which the reactive monomer is a multifunctional monomer.

35. A process coating as claim in claim 30 in which the reactive groups of the silicone are selected from the groups consisting of acrylic groups, mercapto groups, oxirane groups and mixtures thereof.

36. A curable coating as claimed in claim 32 in which the reactive groups of the silicone are selected from the groups consisting of acrylic groups, mercapto groups, oxirane groups and mixtures thereof.

37. A curable coating as claimed in claim 34 in which the reactive groups of the silicone are selected from the group consisting of acrylic groups and mercapto groups and mixtures thereof.

38. A process for forming a release coating substrate which comprises:

(a) applying to the substrate a coating comprising:

(i) from about 5 to about 15 percent by weight of the coating of a reactive silicone having reactive groups selected from acrylic groups, mercapto groups, oxirane groups and mixtures thereof, dispersed as discontinuous phase in from about 95 to about 85 percent by weight of the coating of a continuous reactive resin phase comprising:

(ii) from 50 to 100 percent by weight of the reactive resin of an oligomer reactive with said reactive silicone and selected from the group consisting of acrylated epoxy resins, acrylated polyester resins, acrylated urethane resins and mixtures thereof, and

(iii) from about 50 to 0 percent by weight of the reactive resin of at least one multifunctional monomer, said reactive silicone being a polydimethyl-siloxane having a molecular weight of at least about 2,000, said coating composition having a viscosity of from about 300 to about 10,000 centipoise;

(b) subjecting the coating to the action of sufficient electron beam radiation, ultraviolet radiation or heat or a combination thereof to form a cured coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive and in which substantially all of silicone is anchored in the cured coating and substantially non-transferable to a pressure-sensitive adhesive.

39. A product comprising substrate having bonded thereto a cured release coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive, said coating formed by coreaction of silicone present in an amount of from about 1 to about 30 percent by weight of the coating and a resin contained in a coating composition applied to the substrate, the cure induced by exposure of the applied coating to the action of energy supplied by ultraviolet radiation, electron beam radiation, or a combination thereof induced in a sufficient amount to anchor the silicone to the coating whereby the silicone is substantially non-transferable to a pressure-sensitive adhesive.

40. A product as claimed in claim 39 in which the silicone is present in an amount of from about 5 to about 30 percent by weight of the coating.

41. A product as claimed in claim 39 in which the silicone is present in an amount of from 5 to about 15 percent by weight of the coating.

42. A product comprising a substrate having coating on at least one side thereof with a cured coating composition comprised of from about 1 to about 30 percent by weight of the coating composition of a reactive silicone dispersed as a discontinuous phase in about 99 to about 70 percent by weight of the coating composition or con tinuous reactive resin phase comprising from about 50 to 100 percent by weight of the oligomer reactive with said reactive silicone and from about 50 to 0 percent by weight of the reactive resin of a reactive monomer, said reactive silicone being a polydimethyl siloxane having a molecular weight of at least about 2000 and having pendent therefrom sufficient reactive groups to react with the reactive groups of the oligomer, said coating being cured on exposure to the action of electron beam radiation, ultraviolet radiation, or a combination thereof to form cured coating having a silicone release surface releasable from a pressure-sensitive adhesive with substantially all of the silicone contained in the coating composition being anchored to the cured coating.

43. A product as claimed in claim 42 in which the reactive silicone is present in an amount of from about 5 to about 30 percent by weight of the coating composition.

44. A product as claimed in claim 42 in which the reactive silicone is present in an amount of from about 5 to about 15 percent by weight of the coating composition.

45. A curable coating composition comprising from about 1 to about 30 percent by weight of the coating composition of a reactive silicone dispersed as a discontinuous phase in 99 to 70 percent by weight of the coating composition of reactive resin phase comprising: (i) from 50 to 100 percent by weight of the reactive resin of an oligomer reactive with said reactive silicone and

(ii) from about 50 to 0 percent by weight of the reactive resin of a reactive monomer, said reactive silicone being a polydimethyl siloxane having a molecular weight of at least about 2000 and having pendent therefrom sufficient reactive groups to react with the reactive group of the oligomer on exposure to the action of electron beam radiation, ultraviolet radiation or a combination thereof to form a cured coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive and in which substantially all of the silicone contained in the composition is anchored to the coating to prevent transfer to a pressure-sensitive adhesive.

46. A curable composition as claimed in claim 45 in which the reactive silicone is present in an amount of from about 5 to about 30 percent by weight of the coating composition.

47. A curable composition as claimed in claim 45 in which the reactive silicone is present in an amount of from about 5 to about 15 percent by weight of the coating composition.

48. A process for producing a release coated substrate which comprises:

(a) applying to a substrate a coating composition comprising: (i) from about 1 to about 30 percent by weight of the composition of a reactive silicone dispersed as a discontinuous phase in from about 99 to about 70 percent by weight of the coating composition of a continuous reactive resin phase comprising:

(ii) from about 50 to 100 percent by weight of reactive resin phase of an oligomer reactive with said reactive silicone , and

(b) exposing the coating to the action of sufficient electron beam radiation, ultraviolet radiation or a combination thereof to form a cured coating having a silicone release surface for releasable contact with a pressure-sensitive adhesive and in which substantially all of the silicone groups are anchored in the cured coating and substantially non-transferable to a pressur sensitive adhesive.

49. A process as claimed in claim 48 in which reactive silicone is present in an amount of from about 5 to about 30 percent by weight of the composition.

50. A process as claimed in claim 48 in which reactive silicone is present in an amount of from about 5 to about 15 percent by weight of the composition.