JPS59176333A - Surface modification of polyester - Google Patents

Abstract

PURPOSE:To obtain a molding having excellent adhesion to paints, by treating a molding of a thermoplastic aromatic polyester with an alkali solution and painting the molding. CONSTITUTION:In painting a molding of a thermoplastic aromatic polyester (e.g., polyethylene terephthalate), the molding prior to painting is surface-modified by treatment with an alkali solution (e.g., aqueous NaOH solution) and then painted. An aromatic polyester molding sometimes shows unsatisfactory paint film adhesion to some kinds of paints. Its adhesion to such paints can be markedly improved by subjecting it to the above treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for surface modification of polyester molded articles during painting. More specifically, the purpose is to provide a molded product with excellent adhesion to paint.

High molecular weight linear polyalkylene terephthalates obtained from dicarboxylic acids, mainly terephthalic acid, or their ester-forming derivatives, and diols or their ester-forming derivatives have a high softening point, and are heat resistant, chemical resistant, and light resistant. fibers, films, etc. due to their excellent electrical properties, including
Widely used as molded products. Particularly in fields where molded products are used, painting is often required depending on the application. However, depending on the type of paint, simply painting the molded product may not provide sufficient paint film adhesion.

In such a case, the adhesion can be improved by selecting a primer, but it is preferable from the economical point of view if the adhesion can be improved by simply performing a simple pretreatment.

As a result of intensive research into pre-treatment methods for polyester molded articles, the present inventors have discovered that the adhesion to paint can be significantly improved by treating the surface of polyester molded articles with an alkaline solution, and have thus arrived at the present invention.

That is, the present invention is a pretreatment method with improved paintability, which is characterized by treating a thermoplastic aromatic polyester molded article with an alkaline solution to modify the surface before painting the surface.

The thermoplastic aromatic polyester is at least 80%
A dicarboxylic acid component of up to mol % terephthalic acid and at least 80 mol % ethylene glycol, propane-13-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol It is obtained by direct esterification with an aldiol component using cyclohexane-1,4-dimetatool, or by polycondensation using an ester conversion layer. From an industrial standpoint, polyethylene terephthalate and polybutylene terephthalate are particularly preferred. 0 to 20 mol% of the dicarboxylic acid component of polyalkylene terephthalate is other aromatic dicarboxylic acid having 6 to 14 carbon atoms, aliphatic dicarboxylic acid having 4 to 8 carbon atoms, or alicyclic dicarboxylic acid having 8 to 12 carbon atoms. There may be. Examples of such dicarboxylic acids include fucuric acid, isophthalic acid, 2,6-naphthalenedicarbone, 4
．． Examples include C-diphenyldicarboxylic acid, adipic acid, se/pesic acid, and cyclohexanedicarboxylic acid. Furthermore, even if 0 to 20 mol% of the diol component is other aliphatic diols having 3 to 10 carbon atoms, other alicyclic diols having 6 to 15 carbon atoms, or aromatic diols having 6 to 12 carbon atoms. good.

Examples of such diols include 2,2-dimethylpropane-1,3-diol, 2,2-bis(4t-hydroxycyclohexyl)-propane, 2,2-bis-(
Examples include 4'-hydroxyphenylonpropane and hydroquinone. Furthermore, an amount of oxycarboxylic acid of up to 20 mol % of the dicarboxylic acid component and diol component, e.g.
Epsilon-ogicicaproic acid, hydroxybenzoic acid, etc. may be copolymerized. Of course, polyalkylene terephthalate i'i, trihydric or 1d, tetrahydric alcohol, or trihydric alcohol
It may be branched with a basic or tetrabasic acid. Examples of suitable branching agents include trimesic acid, trimellitic acid,
Examples include trimethylolpropane and pentaerythritol.

The thermoplastic aromatic of the present invention is a polymer or copolymer containing at least 5Q]i amount of such a polyester component.

The alkaline solution used in the present invention is an aqueous or alcoholic solution of an alkali such as sodium hydroxide or potassium hydroxide, and may also be in the form of alcoholade, but is not limited thereto. As a treatment method, the polyester molded product may be immersed in the above-mentioned alkaline solution, washed with water, and then dried. If the dipping temperature is increased, the dipping time can be shortened, which makes it easier to mold.

In addition to the polyester referred to in the present invention, crystallization accelerators, reinforcing fillers, flame retardants, heat stabilizers, light stabilizers as necessary,
Various additives such as colorants can be added.

The crystallization promoter includes known inorganic and organic crystallization promoters. For example, polyoxyalkylene compounds,
Examples include low molecular weight organic esters, ionic copolymers, organic acid salts, inorganic salts, and metal oxides. Specifically, polyalkylene glycols such as polyethylene glycol, polyoxyalkylene compounds having organic acid metal salts such as sodium monosuccinate of polyethylene glycol, and polyoxyalkylene compounds having epoxy groups such as schiffringyl ether of polyethylene glycol are used. Oxyalkylene compounds, polyoxyalkylene compounds having a hydrocarbon group such as monophenyl ether of polytetramethylene glycol, low molecular weight organic enethers such as neopentyl glycol dibenzoate, a-olefins and α, β, -unsaturated dicarboxylic acids. organic salts such as sodium acetate and sodium benzoate, inorganic salts such as calcium carbonate, and metal oxides such as titanium oxide.

A strong filler refers to a fibrous, plate-like, or granular inorganic filler, and by blending these, mechanical strength, heat resistance, and dimensional stability can be further enhanced. Fibers, mineral fibers, carbon fibers, silicon carbide fibers, boron carbide fibers, potassium titanate fibers, gypsum fibers,
Examples include mica, talc, kaolin, clay, asbestos, calcium silicate, calcium sulfate, and calcium carbonate, with glass fiber, mica, talc, and mineral fiber being particularly preferred. These may be used alone or in combination of two or more, and may be surface-treated with a silane coupling agent or the like to improve affinity with the resin. The blending amount is 0 to 60% by weight.

Examples of the flame retardant include compounds containing elements of Groups I, II, II, and V of the periodic table, particularly halogen compounds,
Preferred are phosphorus compounds and antimony compounds. These can be used alone or in combination of two or more. Specific examples of flame retardants include tetraglomobinphenol A or its derivatives, decaglomosiphenyl ether, tetrabromo phthalic anhydride, perchlorocyclopentadiene derivatives, triphenyl phosphate, antimony trioxide, etc. .

Furthermore, the Borienute/L/ of the present invention contains 0 to 10% of other polymers.
50% by weight can be blended. As the polymer,
Polyolefins such as polyethylene and polypropylene, ethylene-propylene copolymers, polystyrene, polymethyl methacrylate, ABS, MBS, acrylic polymers, polyvinyl chloride, polyamide, polyacetal, polycarbonate, polynulfone, polyphenylene oxide, ethylene - Vinyl acetate copolymers, aliphatic polyesters, polysiloxanes and the like.

For coating the molded product of the present invention, any known method such as brush coating, dip coating, roller coating, spraying, flow coating, airless spraying, etc. can be adopted, and depending on the purpose, baking can also be used.

The coated molded product of the present invention has excellent coating film adhesion.

Hereinafter, the present invention will be explained in detail using examples.

In the present invention, the polyester molded body was molded into a flat plate with dimensions of 50 mm x 50 mm and a thickness of 2 mm, which was used as a sample for painting.

Painting was done by air spray, and the adhesion of the paint film was evaluated using a substrate test.

Example 1 A sample plate for a packaging test of reinforced PBT containing 30% glass fiber in polybutylene terephthalate (hereinafter abbreviated as PBT) having an intrinsic viscosity of 1.12 was prepared.
After being immersed in an IJum aqueous solution at 80° C. for 10 minutes, washed with water and dried, it was painted with an alkyd melamine resin paint (Amilan Enamel, manufactured by Kansai Paint Co., Ltd.). Baking was carried out at a temperature of 140° C. for 30 minutes.

The coating film adhesion was 100/100 for base grain Tenu 1-, which was extremely good.

However, in the case of no alkali treatment, even if the coating was degreased with acetone and painted, the result was 1/10C1, so the adhesion of the coating film was poor.

Example 2 Polyethylene tereph clay 1 having an intrinsic viscosity of 0.65
- (hereinafter abbreviated as PET) mixed with 0% glass fiber filtration was treated with alkali and painted in the same manner as in Example 1, and the coating film adhesion was extremely good at 100/100. , D/1 when no alkali treatment is applied.
It was 00.

Example: Modified polyethylene terephthalate (intrinsic viscosity -075) obtained by copolymerizing polyethylene terephthalate with 20% polyethylene glycol (average molecular weight 2000). When a reinforced material containing 30% glass fiber was treated with alkali and painted in the same manner as in Example 1, the coating film adhesion was 100/100, and when no alkali treatment was applied, it was O/100. Met.

Patent applicant Kanebuchi Chemical Industry Co., Ltd. Representative Patent Attorney Makoto Asano

Claims (1)

[Claims] 1. A method for surface treatment of a polyester molded article, which comprises treating the molded article with an alkaline solution and then painting the thermoplastic aromatic polyester molded article.