GB2284424A - Modified polyester resin - Google Patents

Abstract

A flexible polyester resin with excellent surface tack for use as a body filler comprises (A) a modified polyester component with a viscosity of 50 to 100 Pa.s formed from: 1) an unsaturated polyester with an acid value of 25 to 40 mg KOH/g obtained by the reaction of: (a) a diol or diol mixture comprising (i) from 30 to 100 mole % of a diol containing at least one ether linkage, and (ii) from 0 to 70 % of another diol, with: (b) at least one alpha , beta , ethylenically unsaturated dicarboxylic acid or anhydride, 2) at least one monomer copolymerizable and miscible with the unsaturated polyester, and 3) dicyclopentadiene, wherein the molar ratio of diol(s) to dicarboxylic acid or anhydride is from 1.01 to 1.20 and the molar ratio of dicarboxylic acid or anhydride to dicyclopentadiene is from 2.5 to 4, and (B) an amine adduct component with a viscosity of 50 to 110 Pa.s, formed from: 1) at least one nitrogen-epoxy compound obtained by the reaction between (a) a primary amine, (b) a bi-functional epoxy resin, and (c) a monofunctional epoxy resin, and 2) a least one monomer copolymerizable and miscible with the nitrogen-epoxy compound, and (C) at least one accelerator. le

Description

MODIFIED UNSATURATED POLYESTER RESIN FOR IMPROVED PERFORMANCE IN BODY FILLERS.

This invention relates to body filler compositions particularly to body filler compositions containing dicyclopentadiene modified polyester with amine adduct resin exhibiting exceptional flexibility and minimal surface tack.

As body filler is typically used as a masking agent on a wide variety of moveable substrates (e.g. fiberglass, metal, wood, plastic, etc.), excellent adhesion and flexibility are essential characteristics.

Moreover, a rapid cure time under ambient conditions (variable temperature and humidity) are highly desireable characteristics which maximize time efficiency during use of the product.

It is known that polyesters modified with dicyclopentadiene yield compositions with improved flexibility and surface characteristics. Belgian Patent No. 622,370 uses a maleic acid/ethylene glycol polyester with dicyclopentadiene to decrease surface tackiness. U.S. Patent No. 3,448,066 uses 2,2-dimethyl-1.3- propanediol with a dicyclopentadiene modified unsaturated acid or anhydride which are baked at 2040C to yield flexible coatings on metal plates. British Patent No. 962,070 uses dicyclopentadiene modified fumarate-ether glycol polyester with a stabilizer and cobalt naphtalate promoter which is baked at 71.1 -82.2 C after being applied to a wood substrate to form a coating with rapid curing properties.British Patent No. 937,980 discloses a dicyclopentadiene modified poly (oxyalkene) glycol/fumarate polyester coating which can be cured by a combination of melanine urea, cobalt napthalate or bismuth dioxide and 1350C heat. It is even known that epoxy resins may be used with dicyclopentadiene polyesters to form composites. For example in U.S. Patent No. 3,008,493 discloses a centrifugally cured pipe wherein first dicyclopentadiene modified polyester is spun into the mold and then an epoxy resin is added, after which the composite is baked at 54.4" - 65.60C. The resulting product comprised a polyester shell which covered a fibrous filler with an inner layer of epoxy resin.

All of the above compositions are impractical for use as body filler because they require external heat sources for proper curing, and/or do not have sufficient flexibility for excellent performance as body filler. Body filler is typically applied under widely variable conditions (temperature, humidity) to a variety of substrates (fiberglass, wood, metal, plastic, etc.). As the masked item is often mobile and/or subject to stress and shock, flexibility is extremely important to retain surface integrity.

The present invention is an improvement over typical body filler compositions because it is a composition with exceptional flexibility, greatly reduced surface task and very rapid cure time. It is particularly advantageous because it exhibits all of the above properties at low temperatures, or those between 0 and 40"C.

Pastes incorporating the present invention may be sanded to a paintable finish in some cases as soon as 15 minutes after application.

The present invention achieves these advantages through the combination of two primary components (A) and (B) and an efficient amount of at least one accelerator to form a flexible polyester resin with excellent surface tack comprising: (A) a modified polyester component with a viscosity of 50 to 100 Pa.s formed by a combination of: 1) an unsaturated polyester with an acid value of 25 to 40 mg KOH/g obtained by the reaction of: (a) a diol or diol mixture comprising (i) 30 to 100 mole % of at least a diol containing at least one ether linkage, and (ii) 0 to 70% of another diol with (b) at least one a-ss, ethylenically unsaturated carboxylic acid or its anhydride; 2) at least one monomer copolymerizable and miscible with the unsaturated polyester; and 3) dicyclopentadiene; wherein the molar ratio of diol(s) to carboxylic acid/anhydride is about 1.01 to 1.20, and the molar ratio of carboxylic acid/anhydride dicyclopentadiene is about 2.5 to 4; (B) an amine adduct component with a viscosity of 50 to 110 Pa.s, formed by a combination of: 1) at least one nitrogen-epoxy compound obtained by the reaction between (a) a primary amine, (b) a bi-functional epoxy resin and (c) a monofunctional epoxy resin; and 2) a least one monomer copolymerizable and miscible with the nitrogen-epoxy compound; and (C) an efficient amount of at least one accelerator.

The preferred proportions in parts by weight of the main components of the flexible polyester resin according to the invention are: a) from about 92 to 96 % of the modified polyester (A), and b) from about 4 to 8 % of the component (B).

The unsaturated polyesters used according to the invention are prepared by condensing a dicarboxylic acid or its anhydride containing a, p ethylenic unsaturation or mixtures of these with a dialcohol or a mixture of dialcohols. As examples of unsaturated dicarboxylic acids or anhydrides there may be mentioned aliphatic acids such as maleic anhydride, fumaric acid itaconic, citraconic and the like.

Additionally, a small proportion of the unsaturated dicarboxylic acid (up to about 20%) may be replaced with saturated dicarboxylic acids such as orthophtalic, isophtalic, terepthalic, succinic, adipic, sebacic or methylsuccinic acids, and the like.

However maleic anhydride or fumaric acid must be present in a quantity at least about 80 mole % of the total diacid charge.

As examples of the dialcohols which may be used with the dicarboxylic acids may be mentioned 1,2-propanediol (propylene glycol), 1,3-propanediol, dipropylene glycol diethylene glycol, ethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, triethylene glycol, tripropylene glycol and polyethylene glycols.

The esterification of unsaturated carboxylic acids diols is well known, as are the variable properties which result by different combinations of unsaturated acid/anhydrides and diols. A preferred molar ratio of diol to diacid/dianhydride of about 1.05 to 1.15, and more preferably about 1.08 to 1.12 is used with the present invention.

Dicyclopentadiene may be reacted, as is known, with either with the diacid/diacid anhydride before esterification or with the polyester after esterification. The reaction preferably takes place at a temperature of about 1800 to 2100C to avoid ester addition side reaction. However, it is further preferable to minimize ester addition of dicyclopentadiene by reacting it with the polyester, after esterification, to ensure that Diels-Alder double bond addition occurs to a maximal extent.

As examples of the monomers which are copolymerizable and miscible with the unsaturated polyesters are, in a known manner, styrene and substituted styrene such as vinyltoluene and t-butylstyrene. Other ethylenically unsaturated monomers which may, if appropriate, be employed in combination with the alone monomers, in quantities less than about 100/o by weight of the total monomer present, include the lower alkyl (C1 - C4) esters of acrylic acid and methacrylic acid, alpha-methylstyrene, cyclic (such as cyclohexyl) or aromatic (such as benzyl) acrylates and methacrylates, bicyclic (such as isobornyl) methacrylates and acrylates as well as halogenated styrenes such as chlorostyrene and dichlorostyrene, 1,3-butanediol dimethacrylate, diallyl phtalate and the like.

As mentioned previously, the monomer is added in order to dilute the unsaturated polyester resin to a viscosity of about 50 to 100 Pa.s, measured at 250C and 10 r.p.m. (Brookfield RVT, spindle 3) An inhibitor in an amount which will prevent any appreciable amount of polymer formation may be used. The use of inhibitors is well known in the synthesis of unsaturated polyesters. It should be understood that according to the present invention the inhibitor may have the function of increasing storage life of the composition.

The amount and type of inhibitor may vary to control the curing rate, to prevent crazing or cracking as well as to prevent undesireable changes in gel time on long-term storage.

Examples of useful inhibitors are hydroquinone and its derivatives, such as trimethyl hydroquinone; quinone and its derivatives, such as toluhydroquinone, monotertiary butyl hydroquinone; para tertiary butyl catechol, phenothiazine, N-N dialkylhydroxyamine, nitrobenzene, ditertiobutylcatechol, p phenolaniline. di-(2-ethyl hexyl) -octylphenyl phosphite, 2,5 ditertiobutyl-4-hydroxytoluene, methylene blue and mixtures thereof. Typically, the inhibitor is present from about 0.04 % to 0.10 % by weight of the modified polyester component, preferably 0.05 to 0.08 % and most preferably about 0.07 %.

The accelerator or mixture of accelerators are present in either portion A or B of the flexible resin of the invention, or both.

By an efficient amount of accelerator it is meant the minimal amount necessary for the accelerator to have an appreciable effect on the rate of cross-linking. The preferred accelerator is cobalt octoate used at the rate of about 0.05 to 0.40 % by weight of total composition, preferably 0.05 to 0.25 % and most preferably 0.1 to 0.15 %. The well known typical accelerators used for the curing of unsaturated polyesters may also be used in combination with cobalt octoate. Examples of such co-accelerators are copper naphthenate as well as multivalent metallic salts capable of forming multiligand organometallic complexes with amine S.

The primary amines used according to the present invention are preferably primary aromatic amines such as aniline and inertly mono- or multisubstituted anilines. By inertly substituted it is meant substitutions which do not significantly affect the reactivity of the nitrogen atom such as substitutions by alkyl groups, alkoxy groups or halogen atoms. Typical examples include 4-methyl aniline, 4, tertiobutyl aniline and 4-methoxy aniline.

Multi-functional epoxy resins used according to the present invention are namely those which result from the reaction between bisphenol A and epichlorohydrin and which contain on average at least two reactive epoxy groups per molecule. They may be represented by the general formula.

wherein R2 is a bivalent group selected from alkylene groups having from 2 to 12 carbon atoms and those comprising at least one aliphatic or aromatic ring, substituted or not.

The reaction between the primary amine and the multifunctional epoxy resin to form the nitrogenated intermediary compound is typically run at a temperature from about 1200C to 1600C, preferably 140"C to 1600C and most preferably about 1500C.

The molar ratio primary amine : reactive epoxy group is preferably between about 1.1 and 1.6 and most preferably between about 1.2 and 1.4. The nitrogenated intermediary compound is further reacted with the monofunctional epoxy compound such that the remaining secondary amines remaining on said nitrogenated intermediary compound have been substantially converted to tertiary amines.

The monofunctional epoxy compounds used according to the present invention are preferably described by the following formula:

wherein R1, R2 and R3 are each independently alkyl or inertly substituted alkyl radicals of 1 to 5 carbon atoms. By inertly substituted it is meant those substitutions which do not significantly affect the reactivity of the epoxy group Preferably the molar ratio of monofunctional epoxy resin to nitrogenated intermediary compound is between about 0.4 and 0.6, more preferably between 0.45 and 0.55. This reaction is preferably carried out at a temperature of about 1 50 C to 1900C, more preferably 170- to 1900C.

Monomers copolymerizable and miscible with the nitrogenepoxy compound are preferably further copolymerizable with the unsaturated polyester.Thus the same monomer is used to dilute both the unsaturated polyester, and the nitrogenated adduct and therefore the same monomers which were listed previously for diluting the polyester may also be used to dilute the nitrogen compound.

The following examples are intended only to illustrate the invention and not to limit its scope. Unless otherwise indicated, all amounts are in parts by weight.

COMPARATIVE EXAMPLE 1 25.79 parts propylene glycol , 30.94 parts orthophtalic anhydride and 10.28 parts maleic anhydride are cooked at 2100C, until an unsaturated polyester with an acid value of 30 mg KOH/g is obtained. After cooling to 1500C, 0.01 part toluhydroquinone inhibitor is added. The content of the reactor is then discharged into a blender containing 29 parts styrene in such manner that the temperature of the blender is maintained at 750C. The resulting product A is then diluted with 4 parts additional styrene in order to achieve a viscosity of 70 Pa.s. at 250C and 10 rpm (Brookfield RVT, spindle 3).

On the other side, 31.04 parts diethylene glycol, 28.57 parts orthophtalic anhydride and 7.56 parts maleic anhydride are cooked at 210 C, until an unsaturated polyester with an acid value of 42 mg KOH/g is achieved. After cooling of the reactor to 2000C, 8.83 parts tall oil fatty acid (mainly C 18) pine-tree extract are added to the reactor vessel. The composition is then degassed under a gradually reduced pressure and sampled every 30 minutes until a viscosity of 9 Pa.s. at 250C is achieved. The reactor is then cooled to 1200C, after which 0.008 parts hydroquinone inhibitor is added. The content of the reactor is then discharged into a blender already containing 21.2 parts styrene, at a rate such that a blender temperature of 65"C is not exceeded.The resulting product B is then diluted by the further addition of 2.8 parts styrene in order to achieve a viscosity of 60 Pa.s at 250C and 10 rpm (Brookfield RVT, spindle 3).

At last to 47.59 parts of an aromatic tertiary amine marketed under tradename PROPAMINE PLU is heated under nitrogen to 900C, 24.85 parts tetrahydrophtalic anhydride is added. The reactor vessel is then brought gradually to 21 00C and its content cooked until an acid value of 12 mg KOH/g and a viscosity of 65 Pa.s (measured in 70 % styrene) are achieved.

When the reactor has cooled to 1500C, 0.0096 parts hydroquinone inhibitor is added. The content of the reactor is then discharged into a blender already containing 25.81 parts styrene and 0.006 part copper napthenate, at a rate such that the blender temperature does not exceed 75"C. The resulting composition C has a viscosity of 70 Pa.s at 250C.

A conventional body filler is prepared by mixing together for 15 minutes 62.2 parts of product A, 30.05 parts of product B, 0.03 part of a trimethyl hydroquinone inhibitor and 0.03 part of a 4,4' -thio-bis (2 -tertiobutyl-5 -methyl) phenol antioxidant marketed under tradename LOWINOX 44 S 36 and 2 parts styrene. To the above is charged 4.5 parts of product C , and is mixed for 10 minutes. The final composition is then adjusted with either 0.002 part toluhydroquinone inhibitor or 0.5 part of additional product C in order to achieve a gel time of 5 minutes. The composition, having a viscosity at 200C (Brookfield RVT, spindle 3, 10 rpm) of 80 Pa.s, is then tested, with respect to hardness, as mentioned in example 2.

EXAMPLE 2 31.88 parts of diethylene glycol, 21.13 parts maleic anhydride, 0.024 parts triphenyl phosphite, and 0.008 part monotertiobutyl hydroquinone inhibitor are heated under inert gas to 2100C until an unsaturated polyester with an acid value of 50 mg kOH/g is achieved.

12.04 parts dicyclopentadiene is then added and refluxed at 1900C for 30 minutes.

Once an acid value of 35 mg KOH/g and a viscosity of 25 Pa.s at 1250C are achieved, the reactor is then cooled to 1600C and 0.01 part trimethyl hydroquinone inhibitor is then added. The content of a reactor is then discharged into a blender containing 27 parts styrene, 0.035 part trimethyl hydroquinone inhibitor and 0.035 part LOWINOX 44 S 36 antoxidant in such way that the blender temperature does not exceed 700C. Resin A is thus obtained.

On the other side, 0.033 part triphenyl phosphite, 10.910 parts para-toluidine, 25.51 parts of a multifunctional epoxy resin marketed under the tradename EPIKOTE 828 are heated while maintening the reactor temperature at 1800C for 4 hours, which time is sufficient to achieve a viscosity of 20 Pa.s at 1750C.

0.02 part trimethyl hydroquinone inhibitor is then added and the reactor is cooled to 1500C. The content of the reactor is then discharged into a blender containing 42.46 parts styrene, 0.01 part of a 10% solution of copper napthenate in white spirits; and 0.03 part LOWINOX 44 S 36 antioxidant, at a rate such that the blender temperature does not exceed 70"C.

The final composition is adjusted with 2.92 parts of additional styrene in order to bring the viscosity to 100 Pa.s at 250C and 10 rpm (Brookfield RVT, spindle 3). Resin B is thus obtained.

Into a suitable mixing vessel are charged 93.35 parts of resin A, 0.04 part trimethyl hydroquinone and 0.04 part of a 10 % solution of copper napthenate in white spirits. After mixing for 10 minutes, 0.1 part of a 10 % solution of cobalt octoate in white spirits is added, and the resulting composition is further mixed for an additional 10 minutes.

After the second mixing is completed, 6.0 part of resin B is then added and blended for a period of time up to 15 minutes.

0.02 part of cobalt octoate solution and 0.5 part of resin B are then added in order to achieve a flexible body filler having a gel time of 5 minutes at 200C, measured by means of 4 % benzoyl peroxide) and a viscosity of 80 Pa.s measured at 250C and 10 rpm (Brookfield RVT, spindle 3).

50 g of this filler was then catalysed with 2 g of benzoyl peroxide powder and poured into a suitable test container. After 1 hour and after 24 hours of cure at room temperature (20"C), shore hardness D of this sample measured on a Zwick tester. The results o measurements are summarized in the following Table.

EXAMPLE 3 (COMPARAThrEl The conventional body filler of example 1 was formulated by the addition, for 30 parts of the said body filler, of: - o.5 parts BYK W-980, - 44 parts talc, - 8 parts baryte marketed under the tradename VIATON MB/4A, - 1 part fumed silica, - 12 parts calcium carbonate, - 2.5 parts styrene, and - 2 parts titanium dioxide (white pigment).

20 g of the formulated body filler was catalysed with 0.4 g of benzoyl peroxide paste and homogeneized by mixing. The resin was then casted as a 5 cm x 5 cm sample, 5 mm thickness. After gelation, the top face of the casted sample was trimmed to a smouth surface with a suitable knife blade. The Shore D hardness was measured at variable intervals. Results are reported in the following Table.

EXAMPLE 4 The body filler of example 2 was formulated as indicated in example 3. Its shore D hardness was measured as in example 3.

Results are reported in the following table.

Table

EXAMPLE | 1 4 2 | 3 4 10 minutes 32 30 20 minutes 58 62 1 hour 24 24 65 75 24 hours 31 24 67 78 In order to approximate actual use conditions, a sanding test was conducted to determine the ability of invention to be sanded and ground in a typical masking operation. 30 g of filled resin paste was catalysed with 0.6 g of benzoyl peroxide paste, and then spread over a 10 cm x 15 cm sample of polyethylene terephthalate marketed under the tradename MELINEX. The resin was allowed to cure at room temperature for 20 minutes and then sanded by hand with approximately equal pressure applied to each stroke for 50 strokes using 80 grit paper (4.5 cm wide) and dusted off. The loss of weight of the resin was measured following the application process: it was equal to only 0.4 for example 4 instead of 0.68 for example 3.

Claims (14)

1. A flexible polyester resin with excellent surface tack comprising: (A) a modified polyester component with a viscosity of 50 to 100 Pa.s formed by a combination of: 1) an unsaturated polyester with an acid value of 25 to 40 mg KOH/g obtained by the reaction of: (a) a diol or diol mixture comprising (i) from 30 to 100 mole % of at least a diol containing at least one ether linkage, and (ii) from 0 to 70 % of another suitable diol, with:: (b) at least one a, ss, ethylenically unsaturated dicarboxylic acid or its anhydride; 2) at least one monomer copolymerizable and miscible with the unsaturated polyester, and 3) dicyclopentadiene, wherein the molar ratio of diol(s) to dicarboxylic acid or anhydride is from 1.01 to 1.20 and the molar ratio of dicarboxylic acid or anhydride to dicyclopentadiene is from

2.5 to 4, and (B) an amine adduct component with a viscosity of 50 to 110 Pa.s, formed by a combination of: 1) at least one nitrogen-epoxy compound obtained by the reaction between (a) a primary amine, (b) a bi-functional epoxy resin, and (c) a monofunctional epoxy resin, and 2) a least one monomer copolymerizable and miscible with the nitrogen-epoxy compound, and (C) an efficient amount of at least one accelerator.

2. The flexible polyester resin of claim 1 comprising from 92 % to 96 % by weight of the modified polyester and from 4 % to 8 % by weight of the amine adduct component.

3. A flexible polyester resin according to claim 1 or claim 2 wherein the a, p ethylenically unsaturated dicarboxylic acid or anhydride is substituted with up to 20 % by moles by a saturated dicarboxylic acid.

4. A flexible polyester resin according to one of claims 1 to 3, wherein the accelerator is cobalt octoate.

5. A flexible polyester resin according to claim 4, wherein the accelerator is present at a rate of 0.05 to 0.4 % of the total weight of the composition.

6. A flexible polyester resin according to claim 4 or claim 5, further comprising a co-accelerator.

7. A flexible polyester resin according to claim 6 , wherein the co-accelerator is selected from copper naphtenate and multivalent metallic salts capable of forming multiligand organometallic complexes.

8. A flexible polyester resin according to any of claims 1 to 8, further comprising at least one polymerization inhibitor.

9. A flexible polyester resin according to claim 8 wherein the inhibitor is present at a rate from 0.04 % to 0.10 % of the weight of the modified polyester.

10. A flexible polyester resin according to any of claims 1 to 9, wherein the primary amine used for forming the amine adduct component is an aromatic primary amine.

11. A flexible polyester resin according to any of claims 1 to 10, wherein bifunctional epoxy resin used for forming the amine adduct component is represented by the general formula

wherein R2 is a bivalent group selected from alkylene groups having from 2 to 12 carbon atoms and those comprising at least one aliphatic or aromatic ring, substituted or not.

12. A flexible polyester resin according to any of claims 1 to 11, wherein the monofunctional epoxy compound used for forming the amine adduct component is represented by the formula;

wherein R1, R2 and R3 are each independently alkyl or inertly substituted alkyl radicals of 1 to 5 carbon atoms.

13. A flexible polyester resin according to any of claims 1 to 12, wherein the molar ratio of the monofunctional epoxy compound to the nitrogenated intermediary compound is between 0.4 and 0.6.

14. Use of a flexible polyester resin according to any of claims 1 to 13 as a body filler.