WO2000035972A1

WO2000035972A1 - Soluble cyclic carbonate functional polymers and coatings therefrom

Info

Publication number: WO2000035972A1
Application number: PCT/US1999/029546
Authority: WO
Inventors: Dean C. Webster
Original assignee: Eastman Chemical Company
Priority date: 1998-12-15
Filing date: 1999-12-14
Publication date: 2000-06-22

Abstract

Disclosed are polymers with cyclic carbonate functionality which are soluble in common organic solvents and compatible with other polymers and cross-linkers. The copolymers are prepared by the copolymerization of vinyl ethylene carbonate with specific vinyl ester comonomers, that are compatible with vinyl ethylene carbonate, and form soluble and compatible copolymers.

Description

SOLUBLE CYCLIC CARBONATE FUNCTIONAL POLYMERS AND

COATINGS THEREFROM

Background of the Invention Polymers containing the 5-membered cyclic carbonate functionality may be obtained via a number of methods. A recent review (Polymer News, 23(6), 187-192 (1998)) summarizes many of the methods that have been reported in the literature.

Seisan Kenkyu, 25 (7), (1973), describes the synthesis of the homopolymer of vinyl ethylene carbonate and copolymers of vinyl ethylene carbonate with styrene, vinyl acetate, and maleic anhydride. The only vinyl ester comonomer described is vinyl acetate. Copolymerizations were conducted in bulk to low conversion and solubility of the copolymers made was not discussed. This article also describes an attempt to crosslink a vinyl ethylene carbonate containing copolymer with ethylene diamine. This attempt was unsuccessful.

Plasticheskie Massy, No. 2, 1996, 19-22 describes copolymerization of vinyl ethylene carbonate with methyl methacrylate, ethyl acrylate, and styrene. Yields of the copolymers were low and decreased as the level of vinyl ethylene carbonate was increased. The highest level of vinyl ethylene carbonate incorporated into a copolymer was 31.98 mole percent. This study did not include the copolymerization of vinyl ethylene carbonate with any vinyl ester monomers. '

U. S. Pat. No. 5,567,527 describes the formation of coatings by copolymerization of vinyl ethylene carbonate with other comonomers and then crosslinking with multifunctional primary amines.

ACS Symposium Series 704 (Functional Polymers), 303-320 (1998) describes copolymerization experiments with vinyl ethylene carbonate and other unsaturated monomers. Copolymers of vinyl ethylene carbonate with vinyl acetate were incompatible with the solvent at vinyl ethylene carbonate contents of 40 percent and higher. Cyclic carbonate functional acrylic copolymers may be prepared from the copolymerization acrylate and methacrylate esters of glycerin carbonate with other unsaturated monomers and are described for example in U.S. Pat. No. 2,979,514.

Brief Summary of the Invention

This invention involves the formation of cyclic carbonate polymer compositions by reaction of ethylenically unsaturated cyclic carbonate functional monomers with one or more comonomers compatible with cyclic carbonate functional monomers. The resulting compositions have good solubility in common organic solvents, good compatibility with other polymers, and a high level of cyclic carbonate groups.

The polymers of the present invention are useful in coating compositions when crosslinked using multifunctional amines.

Detailed Description

Cyclic carbonate polymer compositions of the present invention may be formed by reaction of ethylenically unsaturated cyclic carbonate functional monomers with other comonomers compatible with cyclic carbonate functional monomers.

Vinyl ethylene carbonate is a preferred ethylenically unsaturated cyclic carbonate functional monomer for free radical copolymerization to form cyclic carbonate polymers. The homopolymer of vinyl ethylene carbonate may also be prepared by free radical polymerization. This polymer, however, has a low molecular weight and is soluble in only dipolar aprotic solvents, such as N-methyl pyrrolidinone, N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide, and the like. These solvents may be undesirable in a number of coating applications due to their toxicity and generally slow evaporation rate from a coating film. In addition, the homopolymer of vinyl ethylene carbonate has poor compatibility with other resins or materials containing functional groups that would react with the cyclic carbonate groups for the formation of a cured thermosetting coating. This incompatibility may lead to incomplete reaction of the cyclic carbonate groups and the groups on the other resin and result in a coating with poor performance.

Vinyl ethylene carbonate may be copolymerized with other ethylenically unsaturated monomers. When copolymerized with esters of acrylic acid, esters of methacrylic acid or styrene, complete incorporation of vinyl ethylene carbonate into the copolymer is not achieved. In order to free the copolymer of the unreacted vinyl ethylene carbonate, additional and costly purification steps must be taken such as vacuum stripping.

The present invention involves the unexpected discovery that particular ethylenically unsaturated monomers, when copolymerized with vinyl ethylene carbonate, yield cyclic carbonate polymers having high levels of cyclic carbonate functionality, good solubility in common organic solvents, and good compatibility with other polymers and resins. In addition, use of these comonomers also yields complete incorporation of vinyl ethylene carbonate into the copolymer, eliminating the need for expensive and time-consuming purification steps. Suitable other ethylenically unsaturated monomers that are within the scope of this invention include vinyl ester monomers. Useful vinyl ester monomers include, but are.not limited to, vinyl acetate, vinyl propanoate, vinyl butyrate, vinyl 2-ethyl hexanoate, vinyl neononanoate, vinyl pivalate, vinyl neodecanoate, vinyl neoundecanoate, vinyl neododecanoate and the like, and mixtures thereof.

Preferred vinyl ester monomers are branched vinyl ester monomers such as vinyl neononanoate, vinyl 2-ethyl hexanoate, vinyl pivalate, and vinyl neodecanoate. Vinyl neononanoate, vinyl neodecanoate, and vinyl neoundecanoate are sold by Shell Chemical Company as VeoVa 9, VeoVa 10, and VeoVa 11 , respectively. Vinyl neodecanoate and vinyl neododecanoate are produced by Exxon Chemical Company as EXXAR NEO 10 and EXXAR NEO 12, respectively. Particularly preferred comonomers are vinyl neononanoate, and mixtures of vinyl neononanoate and vinyl neodecanoate. Also preferred are vinyl ester monomers or mixtures of vinyl ester monomers that are compatible with vinyl ethylene carbonate. Generally, it has been found that vinyl ethylene carbonate is compatible with vinyl ester monomers containing nine carbons or less in the ester portion. Mixtures of a vinyl ester monomer containing ten or more carbon atoms in the ester portion may be made compatible with vinyl ethylene carbonate by the addition of a third monomer such as vinyl acetate.

The copolymerization of vinyl ethylene carbonate with vinyl ester monomers may be effected by any process used for free radical copolymerization including bulk, solution, emulsion, and suspension polymerization. A preferred process of the present invention involves gradual or incremental addition of a mixture of monomers simultaneously with the initiator to a vessel containing preheated solvent.

The choice of free radical initiator depends on the reaction conditions used for the copolymerization. The polymerization may be initiated by conventional free radical initiators such as benzoyl peroxide, di-t-butyl peroxide, t-butyl peroctoate, t-amyl peroxy-2-ethyl hexanoate, t-butyl peroxy-2-ethyl hexanoate, hydrogen peroxide, dicumyl peroxide, t-butyl hydroperoxide, potassium or ammonium peroxydisulfate, 2,2'-azobis(2- methylpropanenitrile), 2,2'-azobis(2-methylbutanenitrile), etc. Redox initiation may be carried out in any usual manner using for example persulfate/metabisulfite, hydrogen peroxide/sodium formaldehyde sulfoxylate, t-butyl hydrogen peroxide/sodium formaldehyde sulfoxylate, etc. Most preferred are those initiators that impart little color to the formed homopolymer or copolymer. Solution polymerizations may be carried out in a solvent appropriate for the monomers, the desired end-use of the polymer, and the polymerization conditions. Solvents may include xylene, toluene, methyl amyl ketone, methyl isobutyl ketone, acetone, ethyl ethoxy propionate, ethylene glycol butyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and the like.

Preferred solvents are those that dissolve both the monomers and the polymer produced, and do not introduce undesired color to the polymer. These solvents include glycol ethers, ketones and glycol ether esters. Mixtures of solvents may also be used.

After the polymerization reaction is complete, the copolymer may be used in solution as is, or the polymer may be isolated by precipitation in a non-solvent, extrusion, or vacuum stripping.

The copolymers of this invention may be used in coatings, inks, adhesives, and plastics. Due to the cyclic carbonate functionality, the copolymers may be crosslinked with multifunctional amines to form thermoset materials. They may also be reacted with other compounds to form polymers with other functional groups.

Simple multifunctional amines useful for crosslinking include, but are not limited to, diethylene triamine; 2-methyl 1 ,5-pentane diamine; triethylene tetramine; aminoethyl piperazine; tris(2-aminoethyl) amine; triaminononane; 1 ,3-cyclohexane bis(methyl.amine); methylene di(cyclohexylamine); m- xylylene diamine; isophorone diamine; and amine functional polypropylene glycol polymers made by Huntsman and sold under the tradename Jeffamine.

Amine-functional materials suitable for this invention may be prepared by reacting the above amines with other material to yield higher molecular weight or amine functionality, as is well-known in the art. The following examples are given to illustrate the invention. It should be understood, however, that the invention is not to be limited to the specific conditions or details set forth in the examples.

EXAMPLES The following examples of the various polymer and coating compositions of the present invention use the following materials:

LUPERSOL 575: t-amyi peroxy 2-ethylhexanoate sold by Elf Atochem North America.

VEOVA-9: vinyl neononanoate sold by Shell Chemical Company. VEOVA-10: vinyl neodecanoate sold by Shell Chemical Company.

EASTMAN PM: propylene glycol monomethyl ether product of Eastman Chemical Company.

The following methods were used to evaluate the polymers prepared as described in the examples. Percent Solids:

The solids content of the polymers was determined by weighing approximately 1 gram of resin solution into an aluminum weighing dish. Additional solvent was added and the dish placed in an oven at 150°C for 60 minutes. After cooling, the dish was weighed and the weight of remaining polymer determined. The percent solids is determined as: 100*(weight remaining/initial weight). Glass Transition Temperature:

The glass transition temperature (Tg) of dried polymer samples was determined using differential scanning calorimetry at a heating rate of 20°C/min. The Tg is reported as the inflection point of the second order transition.

Molecular Weight:

Gel Permeation Chromatography was used to determine the molecular weight of the polymers prepared. Number-average and weight- average molecular weights are reported relative to polystyrene standards. The following methods were used to evaluate the coatings and films prepared as described in the examples.

Methyl Ethyl Ketone Resistance:

Films cured under the specified conditions were rubbed with a methyl ethyl ketone (MEK) saturated cloth according to ASTM D5402. Results are reported as the number of double rubs required for breakthrough of the film to the substrate.

Gloss:

Gloss was measured on cured films using a Byk-Gardner haze-gloss meter.

Konig Pendulum Hardness:

The Konig pendulum hardness was determined using a Byk-Gardner pendulum hardness tester in accordance with ASTM D4366. Hardness is reported as the number of seconds for the pendulum swing to be damped from a 6° swing to a 3° swing.

Impact Resistance:

Forward and direct impact resistance is determined using a falling dart impact tester according to ASTM D2794. Results are reported as the maximum inch-pounds of force where the film remains intact.

Example 1 : Miscibilitv of VEC with Vinyl Ester Monomers

Equal weights of vinyl ethylene carbonate (VEC) and vinyl ester monomers were mixed and shaken well. After mixing the samples were allowed to rest and inspected visually for miscibility. Miscible samples formed one continuous phase while immiscible monomers separated into two distinct layers. The monomers and the results are listed in Table 1. Table 1. Miscibility of VEC with vinyl ester monomers.

Example 2: Comparative Example

A two-piece 500 ml resin kettle was equipped with an overhead mechanical stirrer, heating mantle, condenser, thermocouple, nitrogen inlet. The reactor was charged with 140 g of propylene glycol monomethyl ether and heated with stirring to 80°C. In a separate container, 130 g vinyl ethylene carbonate, 130 g VeoValO, and 10.4 g of Lupersol-575 are mixed. The monomer mixture was added at a uniform rate to the heated solvent using a metering pump over a period of 3 hours. One hour after completion of the monomer addition, 0.5 g Lupersol-575 was added to the reaction mixture. After an additional hour, the reaction mixture was cooled and poured out. The resin had a solids content of 63.6 percent and was hazy, indicating incompatibility with the solvent.

Example 3: Comparative Example

A two-piece 500 ml resin kettle was equipped as described in Example 2. The reactor was charged with 140 g of propylene glycol monomethyl ether and heated with stirring to 80°C. In a separate container, 130 g vinyl ethylene carbonate, 130 g vinyl propanoate, and 10.4 g of Lupersol-575 are mixed. The monomer mixture was added at a uniform rate to the heated solvent using a metering pump over a period of 3 hours. One hour after completion of the monomer addition, 0.5 g Lupersol-575 was added to the reaction mixture. After an additional hour, the reaction mixture was cooled and poured out. The resin had a solids content of 65.1 percent and was hazy, indicating incompatibility with the solvent. Example 4

A two-piece 500 ml resin kettle was equipped as described in Example 2. The reactor was charged with 140 g of propylene glycol monomethyl ether and heated with stirring to 80°C. In a separate container, 130 g vinyl ethylene carbonate, 130 g VeoVa-9, and 10.4 g of Lupersol-575 are mixed. The monomer mixture was added at a uniform rate to the heated solvent using a metering pump over a period of 3 hours. One hour after completion of the monomer addition, 0.5 g Lupersol-575 was added to the reaction mixture. After an additional hour, the reaction mixture was cooled and poured out. The resin had a solids content of 63.6 percent and was clear and colorless, indicating compatibility with the solvent. The resin had a Tg of 72.4°C as determined by differential scanning calorimetry. Example 5

A two-piece 500 ml resin kettle was equipped as described in Example 2. The reactor was charged with 140 g of propylene glycol monomethyl ether and heated with stirring to 80°C. In a separate container, 98.8 g vinyl ethylene carbonate, 161.2 g VeoVa-9, and 10.4 g of Lupersol- 575 are mixed. The monomer mixture was added at a uniform rate to the heated solvent using a metering pump over a period of 3 hours. One hour after completion of the monomer addition, 0.5 g Lupersol-575 was added to the reaction mixture. After an additional hour, the reaction mixture was cooled and poured out. The resin had a solids content of 63.7 percent and was clear and colorless, indicating compatibility with the solvent. The resin had a Tg of 38.2°C as determined by differential scanning calorimetry. Example 6

A two-piece 500 ml resin kettle was equipped as described in Example 2. The reactor was charged with 140 g of propylene glycol monomethyl ether and heated with stirring to 100°C. In a separate container, 98.8 g vinyl ethylene carbonate, 161.2 g VeoVa-9, and 10.4 g of Lupersol-575 are mixed. The monomer mixture was added at a uniform rate to the heated solvent using a metering pump over a period of 3 hours. One hour after completion of the monomer addition, 0.5 g Lupersol-575 was added to the reaction mixture. After an additional hour, the reaction mixture was cooled and poured out. The resin had a solids content of 61.2 percent and was clear and colorless, indicating compatibility with the solvent. The resin had a Tg of 23.4°C as determined by differential scanning calorimetry. Example 7

A two-piece 500 ml resin kettle was equipped as described in Example 2. The reactor was charged with 140 g of propylene glycol monomethyl ether and heated with stirring to 80°C. In a separate container, 124.8 g vinyl ethylene carbonate, 78 g VeoVa-9, 57.2 g vinyl acetate and 10.4 g of Lupersol-575 are mixed. The monomer mixture was added at a uniform rate to the heated solvent using a metering pump over a period of 3 hours. One hour after completion of the monomer addition, 0.5 g Lupersol- 575 was added to the reaction mixture. After an additional hour, the reaction mixture was cooled and poured out. The resin had a solids content of 67.0 percent and was clear and colorless, indicating compatibility with the solvent. The resin had a Tg of 51.7°C as determined by differential scanning calorimetry.

Example 8

A sample of the resin prepared in Example 4 was reduced to a solids content of 50% with additional propylene glycol monomethyl ether. This solution was mixed in various ratios with 50% solutions of either 2-methyl- 1 ,5-pentane diamine and tris(2-aminoethyl)amine as listed in Table 2. Solutions were drawn down on iron phosphate pretreated steel panels and cured in an oven at 80°C for 45 minutes. The coatings formed had solvent resistance as indicated by methyl ethyl ketone (MEK) double rubs indicating the formation of a crosslinked coating.

Table 2. Coating Formulations

Example 9 A one-liter two-piece resin kettle equipped with a heating mantle, mechanical stirrer, thermocouple, nitrogen inlet, and condenser was charged with 315 g of propylene glycol monomethyl ether (Eastman PM). With stirring, the solvent was heated to 80°C. In a separate container, 222.3 g vinyl ethylene carbonate, 362.7 g VeoVa-9 and 23.4 g Lupersol- 575 are mixed. The monomer mixture was added to the heated solvent at a rate of 2.03 g/min. One hour after the addition was complete, 2.0 g of Lupersol-575 was added. After an additional one-hour hold, the mixture was cooled and poured out. The resin solution was clear and colorless and had a solids content of 63.23%. The number average molecular weight by gel permeation chromatography was 1220 and the weight average molecular weight was 1770. Example 10

Into a 500mL, 3-neck round bottom flask equipped with a mechanical stirrer, thermocouple, heating mantle, and condenser was placed 102.32g of the VECΛΛ/9 copolymer solution of Example 9. The resin was heated to 75°C, and to this was added 306ml of a 8M ammonia hydroxide solution over approximately 15 minutes, with stirring overnight. The aqueous layer was decanted, then the solution was concentrated using a rotary evaporator at 60°C and 25mm Hg. The polymer was redissolved in isopropanol to make a 67.1 % solids solution. FTIR showed only a very slight amount of unreacted carbonate present and the formation of urethane indicated conversion of the cyclic carbonate groups to carbamate. Examples 11 - 21

Copolymers were prepared as described in Example 9 using vinyl ethylene carbonate and either vinyl neodecanoate or vinyl neononanoate as the comonomer. The compositions are listed in Table 2. The use of vinyl neononanoate resulted in soluble copolymers at high levels of vinyl ethylene carbonate. The vinyl neononanoate copolymers also have a much higher glass transition temperature than the vinyl neodecanoate copolymers.

Table 3. Examples of VEC Copolymers

V V 9 = vinyl neononanoate

V V 10 = vinyl neodecanoate

Example 22

Coatings were prepared as described in Example 8 with the copolymers described in Examples 13 through 20 using a stoichiometric equivalent amount of diethylenetriamine as the crosslinker. Coatings were applied to iron phosphate pretreated steel panels and cured in an oven at 80°C for 45 minutes. Properties of the coatings are shown in Table 4.

Table 4. Coating Properties

*Dimethylformamide added to compatibilize formulation F=<10 in-lbs

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

CLAIMSWhat is claimed is:

1. A cyclic carbonate polymer composition comprising: a) An ethylenically unsaturated cyclic carbonate functional monomer; b) An comonomer which is compatible with the cyclic carbonate functional monomer; and c) Optionally, one or more additional comonomers.

2. The cyclic carbonate polymer composition of claim 1 wherein the ethylenically unsaturated cyclic carbonate functional monomer is vinyl ethylene carbonate.

3. The cyclic carbonate polymer composition of claim 1 wherein the comonomer is a vinyl ester monomer.

4. The cyclic carbonate polymer composition of claim 3 wherein vinyl ester monomer is selected from the group consisting of vinyl acetate, vinyl propanoate, vinyl butyrate, vinyl 2-ethyl hexanoate, vinyl neononanoate, vinyl pivalate, vinyl neodecanoate, vinyl neoundecanoate, vinyl neododecanoate and mixtures thereof.

5. The cyclic carbonate polymer composition of claim 3 wherein the vinyl ester monomer is a branched vinyl ester.

6. The cyclic carbonate polymer composition of claim 5 wherein the branched vinyl ester is selected from the group consisting of vinyl neononanoate, vinyl 2-ethy.l hexanoate, vinyl pivalate, and vinyl neodecanoate.

7. The cyclic carbonate polymer composition of claim 3 wherein the vinyl ester monomer is a vinyl ester having less than 9 carbon atoms in the ester portion.

8. The cyclic carbonate polymer composition of claim 3 wherein the vinyl ester monomer is a mixture of a vinyl ester having ten or more carbon atoms in the ester portion and vinyl acetate.

9. The cyclic carbonate polymer composition of claim 3 wherein the vinyl ester monomer is a mixture of vinyl neononanoate and vinyl neodecanoate.

10. A crosslinkable coating composition composed of: a. a soluble cyclic carbonate functional copolymer of Claim 1 ; b. a material reactive with the cyclic carbonate functional polymer.

11. The coating composition of claim 10 wherein the material reactive with the cyclic carbonate functional copolymer is a reactive amine containing at least one reactive amine group.

12. The coating composition of claim 11 wherein the reactive amine is selected from the group consisting of diethylene triamine; 2-methyl 1 ,5- pentane diamine; triethylene tetramine; aminoethyl piperazine; tris(2- aminoethyl) amine; triaminononane; 1 ,3-cyclohexane bis(methylamine); methylene di(cyclohexylamine); m-xylylene diamine; isophorone diamine; and amine functional polypropylene glycol polymers.