WO2000050527A1

WO2000050527A1 - Coating method utilizing unsaturated phosphoric acid triesters

Info

Publication number: WO2000050527A1
Application number: PCT/US2000/004232
Authority: WO
Inventors: E. Barritt Troughton, Jr.; Ian C. Quarmby; Pei Wen Jin
Original assignee: Lord Corporation
Priority date: 1999-02-25
Filing date: 2000-02-18
Publication date: 2000-08-31

Abstract

A method of bonding a coating composition to a polymeric substrate comprises applying the coating composition to the polymeric substrate, the coating composition comprising a curable component and a triester of phosphoric acid present in an amount less than 10 percent based on the weight of active components present in the coating composition; and then subjecting the coated polymeric layer to conditions such that a bond is formed between the coating composition and the polymeric substrate.

Description

COATING METHOD UTILIZING UNSATURATED PHOSPHORIC ACID TRIESTERS

Field of the Invention

The invention generally relates to a method of bonding a coating composition to a polymeric substrate using phosphoric components.

Background of the Invention In the manufacture of articles such as, for example, vinyl floor and wall coverings or tiles, typically a flat base layer or substrate, often a felted or matted fibrous sheet, is coated with a vinyl resinous composition which usually contains a foaming agent. The vinyl resin coated base or substrate is then gelled by thermal treatment and may be printed with a decorative pattern. The vinyl resin coated base is provided with another vinyl resin layer commonly referred to as a vinyl resin wear layer. An alternative method of vinyl floor covering manufacture involves forming into sheet form mixtures of a vinyl resin such as vinyl chloride polymer, filler and plasticizer.

In both instances, it is frequently desired to provide the vinyl floor covering or vinyl resin wear layer with a radiation curable top-coat since such coatings are known to possess highly desirable physical and chemical protective characteristics. Unfortunately, it has been found that in many instances the bond between the vinyl resin layer and the acrylated polyurethane is not as strong or as permanent as desired.

One attempt to provide improved adhesion between the vinyl resin layer and the acrylated polyurethane coating composition is proposed in U.S. Patent No. 5,091 ,211 to Richard. Richard proposes the use of a coating composition comprising a monoester or a diester of phosphoric acid to strengthen the bond between a floor covering and an acrylated polyurethane top coating. Although the use of this coating composition by Richard may arguably provide adequate adhesion properties in certain instances, there remains a need in the art for a coating composition which displays improved adhesion along with shelf-stability. There is also a need in the art for a coating composition which provides improved adhesion over a longer time period.

It is an object of the invention to provide a method of bonding a coating composition to a polymeric substrate such that the adhesive strength of the bond between the coating composition and the polymeric substrate is improved.

It is also an object of the invention to provide a coated polymeric substrate exhibiting improved adhesion over long time periods at the interface of the cured coating composition and the polymeric substrate.

Summary of the Invention These and other objects, advantages, and features are provided by the present invention. In one aspect, the invention relates to a method of bonding a coating composition to a polymeric substrate. The method comprises first applying the coating composition to the polymeric substrate. The coating composition comprises an unsaturated thermosettable oligomer and a triester of phosphoric acid defined in greater detail herein that is present in an amount less than about 10 percent based on the weight of active components present in the coating composition. The coated polymeric layer is then subjected to conditions such that the unsaturated thermosettable oligomer and the triester of phosphoric acid become chemically crosslinked and a bond is formed between the coating composition and the polymeric substrate.

In another aspect, the invention relates to a coated polymeric substrate. The coated polymeric substrate comprises a polymeric substrate and a coating composition positioned on the polymeric substrate. The coating composition comprises an unsaturated thermosettable oligomer and a triester of phosphoric acid as defined herein.

In one embodiment, a bond may be present between the coating composition and the polymeric substrate that allows for at least a 70 percent retention of adhesion as determined by the Crosshatch test between the coating composition and the polymeric substrate. More preferably, at least an 80 percent retention of adhesion is obtained, and most preferably, at least a 90 percent retention of adhesion is obtained. 100 percent retention may also be obtained. In various embodiments, the above adhesion retention values may be evaluated after aging the coating over a time period prior to coating the polymeric substrate. For example, the above adhesion retention values may be measured after storing the coating at 50°C for at least 10 days, more preferably for at least 15 days, and most preferably for at least 25 days, and then applying and curing onto the polymeric substrate. The above adhesion retention values are measured at ambient temperature.

The invention is advantageous in that improved adhesion between the polymeric substrate and the coating composition is observed relative to conventional materials. It is believed that the improved adhesion is attributable to the presence of the triester of phosphoric acid since this component is able to diffuse into the polymeric substrate and cure into tightly attached interpenetrating networks with the polymeric substrate. The improved adhesion is exhibited over longer time periods at the interface of the cured coating composition and the polymeric substrate relative to conventional coating compositions. Detailed Description of the Invention

The invention will now be described in greater detail with reference to the preferred embodiments that follow. It should be understood, however, that these embodiments are for illustrative purposes only, and are not to be interpreted as limiting of the invention as defined by the claims.

For the purposes of the invention, the term "polymeric substrate" may include a number of thermoplastic polymeric materials in the form of a base layer which may be used in various applications such as, for example, interior floor coverings and interior wall coverings. Preferably, the polymeric substrate comprises a vinyl resin layer (e.g., a vinyl chloride polymer), along with other materials known in the art such as, for example, fillers and plasticizers. The vinyl resin layer is described in greater detail herein.

The term "coating composition" is typically a part of a wear layer bonded to the polymeric substrate. The wear layer comprises a coating composition, preferably radiation cured, which typically comprises a curable component, a photoinitiator, and a reactive monomer that is polymerizable with the curable component and the triester of phosphoric acid. Advantageously, the triester of phosphoric acid is believed to improve the adhesion from the wear layer to the polymeric substrate or base layer.

Triester of Phosphoric Acid

The triesters of phosphoric acid in the present invention may be formed according to processes known in the art. Also encompassed are vinyl ether triphosphate esters. These compounds are generally described by the general formula (I):

O li

Rι— P-R₂ (I)

R₃ wherein R-i, R₂, and R₃ may be the same or different ester segments. For the purposes of the invention, an "ester segment" which may be employed can be substituted with other groups (functional or non-functional) if so desired, and also may be saturated or unsaturated, or branched or unbranched. In one embodiment, R_{1 (} R₂, and R₃ may be ester-containing segments ranging from C-i to C18 alkyl.

Preferably, R-i, R₂, and R₃ are the same of ^'different and are ester- containing segments having reactive end capping groups. The term "reactive end capping group" refers to an unsaturated carbon-carbon double bond being present at the termination of the R_{1 τ} R₂, and R₃ substituents.

Preferably, R-i, R₂, and R₃ are present in the triesters of phosphoric acids as described by the following formulas:

(Pι

wherein: x, y, and z are independently selected from 0, 1 , 2, or 3; x', y', and z' are independently selected from 1 , 2, or 3; P-i, P₂, and P₃ are defined as reactive capping groups that are independently selected and are represented by the formulas:

H

/

(2) C-H . (3) H

I H

and (4) combinations thereof wherein R is H or CH₃

Eι, E₂, and E₃ are defined as extender units that are independently selected and are represented by the formulas:

o and combinations thereof

wherein R' is H or CH₃; and n, n', and n"" are independently selected and range from O to 18;

and A_L A₂, and A₃ are alcohols in which at least one OH group has reacted to form a phosphate that are independently selected from the formulas:

O-(CH₂)-O- ^■0-f-CH-CH₂-0-

R"

CH ■₂/ O-

■ O- CH-O- I __0^CH₂

, and combinations thereof

wherein n" and n"' may be independently selected and range from 1 to 18; and R" is H or CH₃.

The above formula has the proviso that when any of x, y, or z is zero, a corresponding A-i, A₂, or A₃ cannot be oxygen, and a corresponding P_{1 t} P₂, or P₃ cannot be hydrogen.

Preferred embodiments of formula (1 ) are as follows:

wherein P' is a group represented by Pi, P₂, or P₃ defined hereinabove and wherein R is defined hereinabove.

and

Preferred examples of vinyl ether triphosphate esters are as follows:

and

With respect to the above formulas setting forth R_{1 t} R₂, and R₃, it should be appreciated that when any of the values of x, x', y, y', z, or z' are greater than 1 , different values of each of Ei, E₂₎ E₃, P_{1 t} P₂, or P₃ may be used relative to the corresponding value of x, x', y, y', z, or z'. In other words, for example, when x'=3, each of the three P₃ substituents may be different and may be various combinations of, as an example, vinyl, acrylate, methacrylate, and hydrogen. The amount of triester of phosphoric acid that is included in the coating composition of the invention will vary depending principally upon the particular compound selected but is an effective amount sufficient to improve the bonding strength of the coating composition to the polymeric substrate. Generally, this amount may fall in the range of equal to or less than about 10 percent based on the weight of active components present in the coating composition. For the purposes of the invention, the term "active compo'nents" refers to those components that are capable of curing or chemically crosslinking with other components in the coating composition which includes the triester of phosphoric acid. More preferably, the triester of phosphoric acid is present in an amount less than or equal to about 5 percent based on the weight of the active components, and most preferably less than or equal to about 2 percent based on the weight of the active components.

Active Component

For the purposes of the invention, the term "active component" may be interpreted to include those materials that are curable or are able to chemically react with the triester of phosphoric acid upon exposure to an initiating sources such as, for example, radiation. For the purposes of the invention, radiation may include various forms of energy such as gamma rays, x-rays, UV rays, infrared, microwave, and electric rays. Electron ("E")-beam curing may also be employed if so desired.

A commonly used active component is an unsaturated thermosettable oligomer, preferably one with acrylate or methacrylate functionality. These components include, but are not limited to, an epoxy-acrylate, an epoxy- methacrylate, a polyester-acrylate, a polyester-methacrylate, a polyester-polyol, a polyether-polyol, and mixtures thereof. Examples of these materials are described in U.S. Patent No. 5,091 ,211 to Richard, the disclosure of which is incorporated herein by reference in its entirety. The oligomer may have various molecular weights. Preferably, the oligomer has a weight average molecular weight ranging up to or less than 3000, and more preferably from about 500 to less than or equal to about or at 2000. The oligomer preferably has from about 1.8 to about 3 crosslinking sites per molecule to better facilitate formation of a final crosslinked composition.

Acrylic monomers may be used and typically refer to alpha, beta monounsaturated monocarboxylic acid or esters thereof and includes acrylic acid, and alkylacrylic acids, e.g., methacrylic acids, monohydric and polyhydric alcohol esters of acrylic acid and alkylacrylic acids^", e.g., glycidyl methacrylate, 2- hydroxyethyl methacrylate, and the like. Mixtures and combinations of the above active components may also be used. Other monomers, such as cycloaliphatic epoxy monomers which are commonly used in cationic UV curable systems, may also be employed.

Acrylate polyurethanes such as those described in U.S. Patent No. 5,091 ,21 1 to Richard may also be used.

Reactive Diluent Monomer

The reactive diluent monomer is polymerizable with the active components by exposure to radiation or other means are commonly referred to as reactive diluent systems which can be monofunctional or polyfunctional or combinations thereof. The reactive diluent monomers may or may not be crosslinkable, but they react with themselves and other unsaturated monomers that may be present in the composition. Such combinations of mono- and polyfunctional reactive diluents are presently preferred. Generally, the reactive diluent system will comprise from about 10 to about 65, preferably about 25 to about 50, weight percent, based on total weight of active components used in the coating composition. Particularly preferred reactive diluents are unsaturated polymerizable monofunctional monomeric compounds selected from the group consisting of esters having the general formula:

wherein R° is hydrogen or methyl and R⁴ is an aliphatic or cycloaliphatic, preferably alkyl or cycloalkyl group having 6 to 18, preferably 6 to 9 carbon atoms. Ethoxylated and propoxylated esters or acrylic and methacrylic acid may also be used. Representative of such preferred reactive monomeric diluents, without limitation thereto, are hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, stearyl acrylate, and the corresponding methacrylates. Illustrative of other reactive monofunctional and polyfunctional monomeric diluents which can be employed are styrene, lactone modified esters of acrylic and methacrylic acid, methyl methacrylate, butyl acrylate, isobutyl acrylate, 2-phenoxy acrylate, 2-methoxyethyl acrylate, 2-(N,N-diethylamino) ethyl acrylate, the corresponding methacrylates, acrylonitrile, methyl acrylonitrile, methacrylamide, neopentyl glycol diacrylate, ethylene glycol diacrylate, hexyiene glycol diacrylate, and diethylene glycol diacrylate.

Photoinitiator If so desired, a photoinitiator may be used in the reaction involving components of the coating composition and may be selected from a large group of initiators of which the following are illustrative: benzophenone, benzoin, acetophenone, benzoin methyl ether, Michler's ketone, benzoin butyl ether, xanthone, thioxanthone, propiophenone, fluorenone, carbazole, diethoxyacetophenone, the 2-, 3- and 4-methylacetophenones and methoxyacetophenones, the 2- and 3-chloroxanthones and chlorothioxanthones, 2-acetyl-4-methylphenyl acetate, 2,2'-dimethoxy-2-phenylacetophenone, benzaldehyde, fluorene, anthroquinone, triphenylamine, 3- and 4- allylacetophenone, p-diacetylbenzene, 3-chloro-2nonylxanthone, and the like and mixture thereof. Such photoinitiators are used in amount of from about 0.5 to about 20% by weight, and preferably from about 1 % to about 5% by weight based on the total weight of the coating composition. Cationic photoinitiators such as sulfonium salts can be used when vinyl ether and epoxy monomers are employed.

The coating compositions can also include pigments, fillers, wetting agents, flatting agents, flow control agents, inert solvents, and other additives typically present in coating compositions. Examples of these components are set forth in U.S. Patent No. 5,616,630 to Heinze, the disclosure of which is incorporated herein by reference in its entirety.

In general, exemplary monomers, oligomers, and photoinitiators can be found in "Chemistry and Technology of UV and EB Formulations for Coatings, Paints, and Inks", P.K.T. Oldring, ed., (1991 ), ISBN 0 947798 10.2.

Vinyl Resin Layer As stated hereinabove, the polymeric substrate may be in the form of a layer comprising a vinyl resin. The vinyl resin layer onto which the coating composition can be applied can be any foamable or non-foamable vinyl resin composition known in the art. Often the vinyl resin composition is a dispersion of resin in a liquid medium. The dispersion medium can be water in the case of an aqueous latex, organic solvent as an organosol or plasticizer as a plastisol. The formulation of such vinyl resin latices, organosols and plastisols is well known in the art.

Thus, the vinyl resin layer can be in the form of a vinyl floor or wall tile comprised of a mixture of vinyl resin, filler, plastizer and usually pigment and heat stabilizers blended and formed into sheets by conventional milling and calendaring methods. The preferred and most widely used resin for surface coverings are polymers of vinyl chloride. The vinyl chloride polymers can either be simple, unmixed homopolymers of vinyl chloride or copolymers, terpolymers or the like in which the essential polymeric structure of polyvinyl chloride is interspersed at intervals with the residue of other ethylenically unsaturated compounds polymerized therewith. The essential properties of the polymeric structure of polyvinyl chloride will be retained if not more than about 40 percent of the extraneous copolymer is copolymerized therein. Suitable extraneous comonomers include, for instance, vinyl bromide, vinyl fluoride, vinyl esters, vinyl ethers, cyclic unsaturated compounds such as styrene, acrylic acid and its derivatives, unsaturated hydrocarbons such as ethylene, propylene, isobutene and the like; allyl compounds such as allyl acetate, allyl chloride, allyl ethyl ether and the like; and conjugated and cross-conjugated ethylenically unsaturated compounds such as butadiene, isoprene, chloroprene, 2,3-dimethylbutadiene, 1 ,3-piperlylene, divinyl ketone and the like.

The vinyl resin layers can be utilized per se but are frequently supported on a base layer or substrate prior to being coated with the coating composition. Such substrates are customarily felted or matted fibrous sheets of overlapping, intermingled fibers, although many other forms of sheets, films, or fabrics and many other fibers of natural or synthetic origin have been used.

Thus, the vinyl resin layer of the invention may take the form of vinyl polymer sheet material, especially vinyl floor and wall coverings, including resilient foamed embossed vinyl sheets.

Coating and Curing Coated Polymeric Substrate The coating composition can be applied to the polymeric substrate by any of the known methods as, for instance, roll coating, gravure coating, curtain coating and the like. The viscosity of the coating composition is first advantageously adjusted as by the addition of a suitable diol so as to render it spreadable by the coating means adopted.

Curing conditions for the radiation curable acrylated coatings differ from those employed for more conventional coatings in that such acrylated coatings are cured by being passed through an actinic radiation source such as an ultraviolet lamping unit. Radiation curing by electron beam, gamma and x-ray treatment, and other suitable radiation sources may be employed but must be used at relatively low energy levels, inasmuch as they are essentially examples of very high energy irradiation techniques leading to extremely rapid polymerization. Ultraviolet radiation is the preferred and typical source. In the presence of photoinitiators, such radiation sources induce a photochemical reaction which produces free radicals capable of inducing polymerization. Sources of ultraviolet radiation may be mercury vapor arc lamps, plasma arcs, pulsed xenon lamps and carbon arcs. Mercury vapor arc lamps are preferred and typical, preferably at medium pressure, rather than high pressure or low pressure. Specific wavelengths of light which are most effective will vary, depending primarily upon the particular top surface coating formulation used and the particular photosensitizer employed. It is also to be appreciated that in some instances, combinations of thermal curing and radiation curing conditions may be used.

The present invention will be further described with particular reference to the following specific working examples, wherein there are disclosed preferred and typical embodiments of the present invention. However, it is to be pointed out that such specific examples are primarily illustrative and do not limit the broader principles of the inventive concept and that other specific materials, chemicals processed, etc. may be employed without departing from the scope and the spirit of the appended claims.

The degree of adhesion of the coating composition to the substrate was measured by the Crosshatch Test as described in U.S. Patent No. 5,091 ,211. The Crosshatch Test involves the following procedure: a. Make sure coating is fully cured before testing. b. Keeping the blade perpendicular to the substrate, cut six parallel lines about 1/8" apart using a razor blade. Cut a second set at right angles to the first set. Total number of squares is 25. c. A strip 3 ¹/₂" to 4" of 3M #250 tape is centered over the block of squares parallel to one set of scribe lines. d. Rub tape with tongue depressor to ensure maximum contact of tape with substrate. Use moderate pressure to laminate the tape. e. Remove tape with one quick pull, pulling it off as close to an angle of 180° as possible. f. Repeat steps c, d and e on the same area two more times. g. Record the percentage of squares removed by each of three pulls. (Example: 5%, 10% and 20%.)

In the preparation of tri-2-hydroxy ethylmethacrylate (HEMA) phosphate, toluene was obtained from Aldrich and used as received, triethylamine was obtained from Aldrich and was freshly distilled before use, HEMA was obtained from Aldrich and was used as received, and phosphorus exychloride was obtained from Aldrich and was used as received.

Example 1 Preparation of Tri-HEMA-Phosphate

To a 1 L round-bottomed flask equipped with a thermometer, magnetic stir bar, water-jacketed reflux condenser, and dropping funnel was added 2- hydroxyethylmethacrylate, abbreviated as HEMA (39.04 g, 0.300 mol.Aldrich), triethylamine (30.36 g, 0.300 mol, Aldrich), and diethyl ether (250 mL, Aldrich). The reaction mixture was stirred while cooling to -5°C in a NaCI/ice bath. Phosphorus oxychloride (15.33 g, 0.100 mol, Aldrich) was added dropwise, slowly, to keep the internal temperature below 10°C. The solution was sparged with desiccated air and was stirred before and throughout the addition of the POCI₃ to inhibit polymerization of the reaction mixture. After complete addition of the POCI₃, the reaction mixture was allowed to warm to room temperature. A white solid (presumably Et₃N⁺CI^") precipitated from the solution. The reaction mixture was concentrated to remove the diethyl ether, then taken up in toluene (250 mL). Deionized water (250 ml_) was added and the two phase mixture was stirred vigorously at 70 °C for 4h. The solution was allowed to cool to room temperature and transferred to a separatory funnel. The aqueous layer was drained off and the organic layer was concentrated in vacuo to yield a clear oil (30 g). The product was about 85% pure with about 10% wt. mole toluene as determined by ¹H and ³ P NMR.

Example 2 Preparation of Tri-HEMA-Phosphate

In a 2 L round-bottomed flask equipped with a thermometer, magnetic stir bar, water-jacketed reflux condenser, dropping funnel, and an inlet for dry desiccated air, were added HEMA (195.21 g, 1.500 mol, Aldrich), triethylamine (151.79 g, 1.500 mol, Aldrich), and toluene (600 mL, Aldrich). The resulting homogeneous solution was stirred under an air blanket. Phosphorus oxychloride (76.67 g, 0.500 mol, Aldrich) was added dropwise, slowly, keeping the internal temperature below 30°C. It was necessary to add the POCI₃, very slowly because of the reaction's tendency to exotherm violently and also to use an ice bath to help control the temperature to below 30°C. After complete addition of the POCI₃, the reaction mixture was a thick yellow slurry. This reaction mixture was stirred under air at room temperature overnight. The solid (presumably Et₃N⁺CI^") was removed by vacuum filtration and the filtrate was washed with toluene (2 x 100 mL). The filtered solution was combined with the washings to yield a slightly orange colored, homogeneous solution. The orange toluene solution (800 mL) was transferred to a 2 L, three-necked round-bottomed flask equipped with a magnetic stirrer, thermometer, water-jacketed reflux condenser and a desiccated air inlet. Deionized water (800 mL) was added and the resulting two layers (phases) was stirred vigorously and heated to 70°C using an oil bath for 3 h. Heating was discontinued and the two phases were stirred at room temperature overnight. The organic phase (upper layer) was collected using a separatory funnel (discarding the aqueous phase) and then dried over anhydrous sodium sulfate. After filtration of the organic phase into a 2 L flask,

MEHQ (100 mg) was added and the product concentrated in vacuo to yield 191.0 g of an orange oil (88% yield of which 4% is toluene for a total yield of 84.48%).

Analysis of the reaction mixture by ¹H and ³¹P NMR indicated that the Tri-HEMA- Phosphate was formed containing 4 wt% toluene and a minor impurity assigned to Tetra-HEMA-Pyrophosphate or a related pyrophosphate (³¹P NMR δ - 12.62 in

CDCI₃ at -12.75 and in Acetone-d₆ at δ - 1193).

NMR In Chloroform:

¹H NMR 250 MHz, (CDC1₃): δ 1.92 (s, 9H, CH₃); δ 4.30 (m, 12H, CH₂-CH₂); δ 5.59 (br. S, 3H, H-C=C trans); δ 6.12 (s, 3H, H-C=C cis)

³¹P NMR 250 MHz (CDC1₃, decoupled, internal reference 1 % H₃P0₄ @ 0 ppm): δ 0.335 (s); δ -1.311 (s, main peak); δ -12.75(s)

³¹P NMR 250 MHz (CDC1_3> internal reference 1 % H₃P0₄ @ 0 ppm): δ 0.326

(quintet, J = 7.32 Hz); δ -1.320 (br. Septet, J = 7.32); δ 12.79 (m)

Examples 3-4 Evaluation of Adhesion Promoters in UV Coatings for Vinyl Flooring

Examples 3 and 4 illustrate the adhesive effect of various adhesion promoters for vinyl flooring. A commercial substrate with a PVC weariayer was coated with a 0.001 " uniform layer of the formulations described in Table 1.

Table 1

A B C

Acrylated oligomer resin¹ 51 51 51

Mixture of acrylated monomers² 14.9 44.9 44.9

Additive package³ 2.1 .2.1 2.1

Product from example 2 _ 2% <-.

Ebecryl 170⁴ - 2%

1. Oligomer described in example 5 of U.S. Patent No. 5,616,630

2. Mixture is a blend of ethoxylated trimethylolpropanetriacrylate and propoxylated trimethylolpropanetriacrylate

3. Package of additives includes standard photoinitiators and wetting additives

4. A product of UCB Radcure Inc. of New York, NY.

For each formulation, all the raw materials were added into a glass jar and shaken for 15 minutes on a paint shaker. The coatings were evaluated at day 1 and then stored at 50°C Samples were cured periodically to determine whether the performance of the adhesion promoter was dependent on time.

The formulations and substrates were used at room temperature. The coatings were applied onto the substrate using a drawdown bar (1 mil thickness) and cured in a nitrogen atmosphere under UV light (1 pass under 125/200W/in lamps, 600 mj/cm2). The typical dwell time between coating and curing the samples was 15 seconds. After 24 hours, adhesion was evaluated by the cross- hatch method (using Scotch 250 tape). Results are reported as the percent (area) of coating remaining on the sheet after the first pull.

Example 3 The formulated coatings A and B were stored at 50°C for 34 days. Cured samples were prepared periodically and then tested for adhesion. The percent retention of adhesion is reported below, and was determined according to procedures described herein.

A B

Initial adhesion 69% 100%

Adhesion after 34 days at 50°C 51 % 100%

Example 4 The formulated coatings B and C were stored at 50°C for 30 days. Cured samples were prepared periodically and then tested for adhesion. Formulation C contains a commercially available phosphate ester adhesion promoter that is typical of those used in current UV curable coating formulations. The % retention of adhesion is reported below and is determined according to procedures described herein.

B C

Initial adhesion 100% 91 %

Adhesion after 30 days at 50°C 99% 1 %

Example 3 shows that the use of a Tri-HEMA-Phosphate improves the initial adhesion values and that the improvement is maintained over the duration of the storage stability test. Example 4 illustrates that the use of a Tri-HEMA- Phosphate adhesion promoter offers a significant improvement in adhesion over the duration of the stability test compared to existing commercial adhesion promoters such as those mono- and di-esters of phosphoric acid cited in US 5,091 ,211.

In the examples and specification, preferred embodiments have been set forth. These embodiments, however, only serve to illustrate the invention, but are not to be construed as limiting the invention.

Claims

That Which Is Claimed:

1. A method of bonding a coating composition to a polymeric substrate, said method comprising: applying the coating composition to the polymeric substrate, the coating composition comprising an unsaturated thermosettable oligomer and a triester of phosphoric acid present in an amount less than about 10 percent based on the weight of active components present in the coating composition; and subjecting the coated polymeric layer to conditions such that the unsaturated thermosettable oligomer and the triester of phosphoric acid chemically crosslink and a bond is formed between the coating composition and the polymeric substrate.

2. The method according to Claim 1 , wherein the triester of phosphoric acid is selected from the group consisting of:

wherein: x, y, and z are independently selected from 0, 1 , 2, or 3; x', y', and z' are independently selected from 1 , 2, or 3; Pi, P₂, and P3 are defined as reactive capping groups that are independently selected and are represented by the formula:

and (4) combinations thereof

wherein R is H or CH₃

E_L E₂, and E₃ are defined as extender units that are independently selected and are represented by the formulas:

_ -₍(_CCHhM₂)__₀n_

, and combinations thereof

wherein R' is H or CH₃; and n and n' are independently selected and range from 1 to 18;

and A_L A₂, and A are alcohols in which at least one OH group has reacted to form a phosphate that are independently selected from the formulas:

0-^"

CH₂

,0.

CH-O-

I -^CH2

C— t — CH₂-O-j— and combinations thereof

wherein n" and n'" may be independently selected and range from 1 to 18; and R" is H or CH₃.

3. The method according to Claim 1 , wherein the coating composition comprises less than about 5 percent of the triester of phosphoric acid based on the weight of active components present in said coating composition.

4. The method according to Claim 1 , wherein the coating composition further comprises a photoinitiator, and wherein said subjecting step comprises subjecting the coated polymeric substrate to radiation.

5. The method according to Claim 1 , wherein the polymeric substrate comprises a vinyl resin.

6. The method according to Claim 1 , wherein the coating composition further comprises an acrylourethane.

7. The method according to Claim 1 , wherein the coating composition comprises at least one reactive diluent monomer.

8. The method according to Claim 1 , Wherein the polymeric substrate is present in a floor covering or wall covering.

9. The method according to Claim 1 , wherein the unsaturated thermosettable oligomer has acrylate or methacrylate functionality.

10. A method of bonding a polymeric substrate to a coating composition, said method comprising: applying the coating composition to the polymeric substrate, the coating composition comprising an unsaturated thermosettable oligomer, a photoinitiator, and a triester of phosphoric acid present in an amount less than 10 percent based on the weight of active components present in the coating composition; and subjecting the coated polymeric layer to conditions such that the unsaturated thermosettable oligomer and the triester of phosphoric acid chemically crosslink and a bond is formed between the coating composition and the polymeric substrate.

11. The method according to Claim 10, wherein the triester of phosphoric acid is selected from the group consisting of: (Pι

wherein: x, y, and z are independently selected from 0, 1 , 2, or 3; x', y', and z' are independently selected from 1 , 2, or 3;

Pi, P₂, and P₃ are defined as reactive capping groups that are

H rf _H (2) / ^c^ (3) H

I H

and (4) combinations thereof

wherein R is H or CH₃ Ei, E₂, and E₃ are defined as extender units that are independently selected and are represented by the formulas:

and combinations thereof

and Aι, A₂, and A₃ are alcohols in which at least one OH group has reacted to form a phosphate that are independently selected from the formulas:

O— (CH₂)-0— -O—F-CH-CH₂-O-

R" n

CH₂

,0. I

CH-O- I ₀-CH₂

C— f — CH₂-O — _t and combinations thereof 4

12. The method according to Claim 10, wherein the coating composition comprises less than 5 percent of the triester of phosphoric acid based on the weight of the active components.

13. The method according to Claim 10, wherein the polymeric substrate comprises a vinyl resin.

14. The method according to Claim 10, wherein the coating composition further comprises an acrylourethane.

15. The method according to Claim 10, wherein the coating composition comprises at least one reactive diluent monomer.

16. The method according to Claim 10, wherein the polymeric substrate is present in a floor covering or wall covering.

17. A coated polymeric substrate comprising: a polymeric substrate; and a coating composition positioned on the polymeric substrate, the coating composition comprising an unsaturated thermosettable oligomer and a a triester of phosphoric acid present in an amount less than 10 percent based on the weight of active components present in the coating composition; wherein the unsaturated thermosettable oligomer and the triester of phosphoric acid form a chemically crosslinked structure and wherein a bond is present between the coating composition and the polymeric substrate.

18. The coated polymeric substrate according to Claim 17, wherein the triester of phosphoric acid selected from the group consisting of:

O

wherein: x, y, and z are independently selected from 0, 1 , 2, or 3; x', y', and z' are independently selected from 1 , 2, or 3; Pi, P₂, and P₃ are defined as reactive capping groups that are independently selected and are represented by the formulas:

⁽²> Λ I -H ⁽³⁾

H

and (4) combinations thereof

wherein R is H or CH₃

Ei, E₂, and E₃ are defined as extender units that are independently selected and are represented by the formulas:

w -CH-CH₂— O-j- — C — (CH₂)__o — and combinations thereof

O— (CH₂)-O- OH-CH-CH₂-O-

R"

CH₂

O

CH-O- I ,CH₂

.0^"

-CH₂ — O- - and combinations thereof

19. The coated polymeric substrate according to Claim 17, wherein the polymeric composition comprises a vinyl resin.

20. The coated polymeric substrate according to Claim 17, wherein the coating composition further comprises an acrylourethane.

21. An article of manufacture comprising the coated polymeric substrate according to Claim 16.

22. The article of manufacture according to Claim 21 , said article of manufacture being a floor covering or a wall covering.