WO2008080440A1

WO2008080440A1 - Organic powder useful as the replacement of mineral filler in composites

Info

Publication number: WO2008080440A1
Application number: PCT/EP2007/001695
Authority: WO
Inventors: Frédéric Bauchet; Valérie ENGLERT
Original assignee: Cook Composites & Polymers Company; Cray Valley S.A.
Priority date: 2006-12-29
Filing date: 2007-02-28
Publication date: 2008-07-10
Also published as: ZA200904391B; CN101605847A; CN101605847B

Abstract

The invention is about organic powder materials useful as the replacement of mineral or inorganic fillers in gel coats or composites. The organic powder materials have particle size less than 60 µm and are visually non-differentiable in composites. The gel coat materials with the organic powder have uniform color appearance and have improved color stability when exposed to moisture.

Description

ORGANIC POWDER USEFUL AS THE REPLACEMENT OF MINERAL FILLER IN COMPOSITES

The present invention is in the field of coatings such as gel coats, barrier or skin coats, or molding compound compositions more particularly, gel coat or molding compound compositions with an organic powder filler material and articles coated with such coatings, as gel coats, or made from such molding compound compositions.

Gel coated composite articles are commonly used in a wide variety of applications. Gel coats provide improved weathering characteristics and surface appearance. In some applications, e.g., countertops and bathroom fixtures, the composite article preferably simulates the appearance of natural materials such as granite, marble or other stone. A number of methods are known to produce the simulated stone appearance. US patent 5,504, 126 discloses a simulated mineral article, comprising a discrete suspended plastic material and a continuous thermoplastic matrix. The plastic material and the thermoplastic matrix are visually distinguishable from each other and each contains a coupling agent. The patent also provides a method of preparing a simulated mineral article which entails preparing a liquid thermoplastic to serve as a matrix and then suspending a plastic material therein. The plastic material is composed of a thermoset plastic made from resin which comprises an acid component having thermoplastic characteristics.

US patent 5,476,895 describes a sprayable coating composition that is useful for forming a simulated granite surface having high-impact strength, superior hardness and an aesthetically-pleasing look. The coating composition has a gel coat and granules which include thermoplastic and thermoset plastic components. The gel coat and granules are visually differentiable from each other, substantially immiscible. The granules and gel coat are visually differentiable from each other, substantially immiscible and isopycnic in density : the granules normally have similar properties as the gel coat, e.g. resistancy, specific gravity, etc. The granules remain evenly dispersed and suspended within the gel coat. The composition, when combined with a hardener, may be sprayed into a mold and backed with fiber glass, plastic or other suitable resin to form a panel or similar structure, or may be directly applied to a surface to provide a simulated-granite appearance. Japan patent 02-102156 describes a hot press molding resin composition to improve transparency and gloss by hot-pressing a molding composition containing an unsaturated polyester resin, curing agent, cured product powder of an unsaturated polyester resin, specific inorganic filler and mold releasing agent. The cured product powder of an unsaturated polyester resin has the particle size less than 90 um, and the molded articles are the artificial translucent stones.

Japan patent 06-25539 describes colored resin particles for decorated moldings. The colored resin particles were obtained by dissolving the thermoplastic resin, in uncured thermosetting resin. Filler and pigment were then added into the resin solution and the resin solution was cured and crushed into small pieces.

Conventional gel coat compositions contain thermoset resin, monomer, fillers, pigment, promoters, and additives. The gel coats are useful as the exterior paint layer for boats, panels, and bathroom fixtures such as shower stalls, bath tub enclosures and the like. Typical inorganic materials used as fillers in colored gel coat are clay, magnesium oxide, magnesium hydroxide, calcium carbonate, calcium silicate, mica, aluminum trihydrate, aluminum hydroxide, barium sulfate, talc, etc. These fillers are inorganic and are normally made from mineral sources.

The invention concerns powder materials useful as the replacement of mineral fillers in coatings such as gel coats, barrier or skin coats and in other type of composites materials or molding compounds compositions. The powder materials are made from cured organic materials or combination of cured organic and inorganic materials. The amount of cured organic material to inorganic material is from 50/50 to 100/0 by weight. The maximum particle size of the powder materials is less than 60 um. The particle size of the organic filler has a typical range of 0.1 to 45 um, and is visually non-differentiable when incorporated into the composites. The cured organic materials used to make the organic powders are the reaction products of unsaturated polyester resins, unsaturated polyester/polyurethane hybrid resins, cross-linkable acrylics, and cross-linkable melamine, or thermoplastic polymers that do not dissolve or swell in monomers. The organic materials have glass transition temperature above 50⁰C, do preferably above 60⁰C. The reaction products have a degree of cure (conversion) above 70%, preferably above 80%. The reaction products have less than 10 wt% volatile content, preferably less than 5% volatile content.

The reaction products are made through a preparation method comprising typical curing processes of thermosetting resins. The typical curing process of thermosetting resin comprises adding initiators and promoters to a resin or resin solution and (i) curing at ambient temperature, (ii) heating the material to elevated temperature to cure the resin, (iii) curing by exposing the resin to UV light, or (iv) curing by exposing the resin to microwave. The cured materials can be post-cured at elevated temperature to further increase the degree of cure and removal of the volatile materials. The cured organic materials then go through a size reduction process to obtain the final powder product with proper size range. The traditional size reduction process includes ball mill, cryogenic grinding, hammer mill, jet mill, roller mill, etc.

The gel coat materials with the organic powder have uniform color appearance and have improved color stability when exposed to moisture. The amount of powder material in coating compositions, like gel coats or barrier coats or skin coats or in molding compounds or composite materials compositions, like SMC or BMC, is from 10 to 50 wt% of total of the coating or the molding composition, more particularly 10 to 50 wt% of the total of a gel coat composition or formula.

The invention is about powder materials useful as the replacement of mineral fillers, such as clay, magnesium oxide, magnesium hydroxide, calcium carbonate, calcium silicate, mica, aluminum trihydrate, aluminum hydroxide, barium sulfate, talc, etc., in gel coats, and in other type of composites materials or molding compound compositions. The mineral filler can be entirely or partially replaced by the powder material in the application. The powder materials are made from organic materials or combination of cured organic and typical inorganic materials, as disclosed above.

The unsaturated polyester resin has at least one dicarboxylic alkene moiety and is preferably an oligomer of an α,β-ethylenically unsaturated dicarboxylic acid compound obtained by the condensation reaction of one or more of a saturated di- or polycarboxylic acid or anhydride and an unsaturated di- or polycarboxylic acid or anhydride with a glycol or a polyhydric alcohol. The unsaturated polyester resin can also be prepared from unsaturated di- or polycarboxylic acid(s) or anhydride(s) with glycols and/or polyhydric alcohol(s). Examples of suitable saturated di- or polycarboxylic acids include isophthalic, orthophthalic, terephthalic, adipic, succinic, sebacic acid and mixtures of two or more of these compounds with isophthalic acid being preferred. Typical unsaturated carboxylic acids or anhydrides include maleic acid, fumaric acid, citraconic acid, chloromaleic acid, allyl succinic acid, itaconic acid, mesaconic acid, their anhydrides and mixtures of two or more such compounds, with maleic anhydride being the preferred choice. Examples of polyhydric alcohols which are useful in the invention include neopentyl glycol, ethylene glycol, diethylene glycol, Methylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, polyethylene glycols, glycerol, mannitol, 1,2-propanediol, pentaerythritol, 1,6- hexanediol, 1,3-butylene glycol and mixtures of two or more of such compounds. The production of such resins is well-known to those skilled in the art and, additionally, many suitable resins are commercially available from resin manufacturers, such as Cook Composites & Polymers Company.

The unsaturated polyester resin composition also contains ethylenically unsaturated monomer. The ethylenically unsaturated monomer can be any ethylenically unsaturated monomer capable of crosslinking the unsaturated polyester resin via vinyl addition polymerization.

Examples of useful ethylenically unsaturated monomers are styrene, o-, m-, p-methyl styrene, methyl acrylate, methyl methacrylate, t-butylstyrene, divinyl benzene, diallyl phthalate, triallyl cyanurate and mixtures of two or more unsaturated monomers. The preferred monomer is styrene because it provides an economical monomer solution.

The initiators useful in producing the cured resin compositions of this invention are vinyl polymerization catalysts such as peroxides, persulfldes, perborates, percarbonates, and azo compounds or any other suitable catalyst capable of catalyzing the vinyl polymerization of the polyester polyol and/or the ethylenically unsaturated monomer. Illustrative of a few such catalysts are benzoyl peroxide (BPO), tertiaryburyl peroxybenzoate (TBPB), 2,2'-azo-bis- isobutyronitrile, dibenzoyl peroxide, lauryl peroxide, di-t-butyl peroxide, diisopropyl peroxide carbonate and t-butyl peroxy-2-ethylhexanoate. Promoters can also be used in combination with vinyl polymerization peroxide catalysts to control the rate of free radical initiation. A common benzoyl peroxide promoter is N.N-diethylaniline.

Coating compositions and particularly curable coating compositions like gel coat, barrier or skin coat compositions, or molding compound compositions can be formulated with one or more organic powder materials of this invention in the usual method, while the said powder materials being visually non- differentiable in the said coatings or molding compound compositions.

Gel coat compositions include pigment, promoters, catalysts, stabilizers, extenders, and the like as practiced in the art. The amount of organic powder material in a coating composition like a gel coat, barrier coat or skin coat or in a molding compound composition, like SMC or BMC, is from 10 to 50 wt% of the total of the coating or of the molding composition, more particularly 10 to 50 wt% of the total gel coat composition or formula. The gel coat materials with the organic powder have uniform color appearance and have improved color stability when exposed to moisture.

The amount of the said powder material in the said composition is from 10 to 50 wt% of the total composition, preferably from 10 to 40 wt%.

More particularly the said coating composition is a gel coat, or barrier coat or a skin coat composition. It may also be a molding compound composition like SMC or a BMC composition.

Another subject of the invention relates to a use a method of use of at least one powder material as defined according to the invention, in coatings such as gel coats, barrier coats, skin coats or use in composites or molding compound compositions with the said powder materials being visually non-differentiable in the said coatings or composites.

A last subject of the invention relates to a molded and/or a coated article, resulting from at least one molding and/or coating composition of the invention. More particularly, the said molded article is a molded composite article and the said coated article is a gel coated article, and even more particularly it is a gel coated composite with the said composite being obtained from a molding compound composition as defined according to the invention.

The following examples may illustrate the preparation of organic fillers and of coating compositions like gel coats with the organic filler of the invention and their performances.

Example 1

1.5 wt% initiators , TBPB (tert-butyl perbenzoate) was added into an unsaturated polyester resin containing 60 wt% PG/NPG/IPA/MA (propylene glycol/neopentyl glycol/isophthalic acid/maleic anhydride) type resin solid and 40 wt% styrene monomer. The resin used was a base resin is CCP STYPOL brand gel coats. The resin solution was poured into metal mold at 150⁰C and cured for 3 minutes. The cured resin was then broken into small pieces about 6.45 cm² (1 square inches) by hammer. The pieces were then grinded to powder with the maximum particle size of 45um with a hammer mill.

Example 2

0.15% of 6% cobalt and 1.5 wt% initiators methyl ethyl Ketone peroxide (MEKP) was added into an unsaturated polyester resin containing 60 wt% PG/NPG/IPA/MA type resin solid and 40 wt% styrene monomer (the same resin as used in Example 1). The resin solution was poured into a metal mold at ambient temperature and cured for 12 hours. The cured resin was then post- cured at 65°C for 24 hours and broken into small pieces about 6.45 cm² (1 square inches) by hammer. The pieces were then grinded to powder with the maximum particle size of 45um with a hammer mill.

Example 3

A gel coat composition is then prepared by blending the following ingredients according to Table 1 below :

Table 1

Example 4

A gel coat composition is then prepared by blending the following ingredients :

Table 2

Comparative Example 5

A low VOC gel coat composition is then prepared by blending the following ingredients :

Table 3

The gel coat from Exhibit 3 was very stable in that it did not gel after three months storage. The gel coat of Example 4 was not stable in that it gelled within one week.

Examples 6 and 7

Pigmented gel coat compositions were prepared by adding 7.5 wt% black pigment paste into the gel coat composition shown in Examples 3 and 5 :

Table 4

The resulting gel coats had a Brookfield viscosity of 18000 - 20000 cps at 4 rpm at 77°C and a thixotropic index of 5.0-7.0. 1.8% methyl ethyl ketone peroxide (MEICP) is used to cure gel coat. The gel time is around 15 minutes and cure time is around 60 minutes. Two gel coated laminates were prepared by spraying the catalyzed gel coat onto a mold and let the gel coat cure at the ambient temperature for about one hour. The laminate was then put on the gel coat to about 3.5 mm in thickness. The color of cured gel coat was measured by a spectrophotometer. Part of the gel coated surface was sanded and buffed, and the color difference before and after buff back was also compared with the spectrophotometer. Table 5 shows the color difference of cured gel coat from Examples 6 and 7. The results indicated the color difference before and after buff back were much smaller for the gel coat sample from Example 6.

Table 5

Example 8 Comparison of 100 Hours Water Boil of Laminates

The gel-coated laminates were prepared with the gel coat samples from Examples 6 and 7. The laminates had the cured gel coat thickness around 15 mils. The panels were immersed in boiling de-ionized water for 100 hours, and the color difference before and after boil test was measured by a spectrophotometer. The results indicated the gel coat sample from Example 6 has much less color change compared to the gel coat sample from Example 7.

Table 6

Claims

1. Powder materials useful as the replacement of mineral fillers in gel coat, and in other type of composites materials or molding compounds compositions.

2. Powder materials as defined according to claim 1, wherein they are organic materials or combination of organic and inorganic materials with the amount of the said organic material to the said inorganic material being from 50/50 to 100/0 by weight.

3. Powder materials as defined according to claims 1 or 2, wherein they have maximum particle size of less than 60 μm.

4. Powder materials as defined according to claim 3, wherein they have a typical range of 0.1 to 45 μm, and are visually non-differentiable when the particles are incorporated into composites.

5. Powder materials as defined according to any one of claims 1 to 4, wherein they are the reaction products of : unsaturated polyester resins, unsaturated polyester/polyurethane hybrid resin, cross-linkable acrylics, melamines, or thermoplastic polymers not soluble or not swellable in monomers.

6. Powder materials as defined according to any one of claims 1 to 5, wherein they have glass transition temperature above 50⁰C, preferably above 60⁰C.

7. Powder materials as defined according to claims 5 or 6, wherein, the said reaction products as defined according to claim 5, have a degree of cure (conversion) above 70%, preferably above 80%.

8. Powder materials as defined according to any one of claims 5 to 7, wherein, the said reaction products as defined according to claim 5, have less than 10 wt% volatile content, preferably less than 5 wt% volatile content.

9. Powder materials as defined according to any one of claims 5 to 8, wherein, the said reaction products as defined according to claim 5, can be made by adding initiators and promoters to the resin and curing at ambient temperature, or heating the material to elevated temperature, or exposing to UV light, or exposing to microwave.

10. Powder materials as defined according to claim 8, wherein they can be further post-cured at elevated temperature to improve the degree of cure and remove the volatile content.

11. Method of preparing the powder material as defined according to any one of claims 1 to 10, comprising a curing process of thermosetting resin comprising adding initiators and promoters to the resin or resin solution and (i) curing at ambient temperature, (ii) heating the material to elevated temperature to cure the resin, (ill) curing by exposing the resin to UV light, or (iv) curing by exposing the resin to microwave.

12. Method according to claim 11, further comprising a step of post-curing at elevated temperature to further increase the degree of cure and removal of the volatile materials

13. A coating or a molding compound composition, wherein it comprises at least one powder material as defined according to any one of claims 1 to 10, the said powder materials being visually non-differentiable in the said coatings or molding compound compositions.

14. A coating composition or molding composition according to claim 13, wherein the amount of the said powder material in the said composition, is from 10 to 50 wt% of the total composition.

15. A coating composition according to claims 13 or 14, wherein it is a gel coat, or barrier coat or a skin coat composition.

16. A molding compound composition according to claims 13 or 14, wherein it is an SMC or a BMC composition.

17. Use of at least one powder material as defined according to any one of claims 1 to 10, wherein it is in coatings from gel coats, barrier coats, skin coats or in composites and wherein the said powder materials are visually non-differentiable in the said coatings or composites

18. A molded and/or coated article, wherein it results from at least one molding and/or coating composition as defined according to any one of claims 13 to 16.

19. An article according to claim 18, wherein the said molded article is a molded composite article and the said coated article is a gel coated article.

20. An article according to claims 18 or 19, wherein it is a gel coated composite, the said composite being obtained from a molding compound composition as defined according to any one of claims 13, 14 or 16.