JPH04130169A - Coating composition for polypropylene resin - Google Patents

Abstract

PURPOSE:To provide the title composition improved in solvent resistance, gasoline resistance, coating behavior and adhesiveness by combining a specific propylene-alpha-olefin copolymer with an epoxy compound. CONSTITUTION:A propylene-alpha-olefin graft copolymer (A) having a weight average molecular weight of 3,000-35,000 is obtained by the graft copolymerization of a propylene-alpha-olefin copolymer (e.g. propylene-1-butene copolymer) containing 55-85 mole % propylene with 0.1-15wt.% alpha,beta-unsaturated dicarboxylic acid (anhydride) [e.g. maleic acid (anhydride)J. Then, a coating composition for PP resin is obtained by mixing 100 pts.wt. component A with 0.5-50 pts.wt. compound or resin (B) having 2 or more epoxy groups per molecule. The composition is heated at ordinary temperatures to 150 deg.C to crosslink the carboxyl group or acid anhydride group of the component A with the epoxy group of the component B, so that cured films are formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves adhesion when painting the surface of a polypropylene resin molded product or when bonding another base material to a polypropylene resin. The present invention relates to coating compositions used for this purpose.

[Conventional technology]

Polypropylene resins have excellent properties and are inexpensive, so they are used in large quantities in home appliances, automobile parts, and the like. However, since polypropylene resin is nonpolar, it has the disadvantage that it is difficult to paint or adhere.

In order to solve these drawbacks, conventionally, before painting or adhering polypropylene resin molded products, the surface of polypropylene resin molded products is treated with flame treatment, corona discharge treatment, plasma treatment, etc. to improve adhesion. Whether or not improvements have been made, the processing operations are complicated and it is difficult to uniformly process objects with complex shapes, making it impractical.

In addition, primer compositions containing chlorinated modified polypropylene as a main component have been proposed, for example,
No. 916, Japanese Patent Publication No. 57-36128, Special Publication No. 63-3
No. 6624, etc. However, primers made of these chlorinated compounds have a common drawback in that although they have excellent adhesion to polypropylene, they have poor weather resistance and solvent resistance, and their uses are extremely limited.

On the other hand, various brimer compositions containing modified polyolefin as a main component have been proposed. For example, Tokko Sho 62-2
No. 1027, etc., discloses a brimer composition in which maleic acid or its anhydride is graft copolymerized to a propylene-ethylene copolymer. Gasoline-based or insufficient. Furthermore, Japanese Patent Publication No. 52-47487 discloses a coating composition in which an ethylene acrylic acid copolymer is combined with an epoxy compound, which has no adhesion to polypropylene.

[Problems to be Solved by the Invention] As mentioned above, in order to paint or bond polypropylene, is it realistic to apply primer treatment? Both techniques have drawbacks, such as the lack of corrosion resistance. There has been no brimer composition suitable for automotive applications that require such severe performance.

Furthermore, the present inventors have already proposed a coating composition in which α-unsaturated unsaturated carboxylic acid or a derivative thereof is graft-copolymerized onto a propylene-butene copolymer (9
(filed on September 5, 2013) Still solvent resistant for applications that require severe performance.

There is room for improvement in gasoline resistance.

The present invention aims to solve these problems and provide a coating composition that can improve the paintability and adhesion of polypropylene resins.

[Means to solve the problem]

In order to achieve the above object, the present invention has been achieved as a result of various studies. That is, a propylene-α olefin copolymer (1) obtained by graft copolymerizing 01 to 15% by weight of an α-unsaturated unsaturated dicarboxylic acid or its acid anhydride, and a compound having two or more epoxy groups per molecule. Or a coating composition for a polypropylene resin, which contains resin (2) as a main component and forms a cured film through a crosslinking reaction between the carboxyl group or acid anhydride group of (1) and the epoxy group of (2). The product has excellent adhesion to polypropylene resin, appearance, impact resistance, moisture resistance,
The above objective was achieved by discovering that the composition exhibited good gasoline resistance in addition to water resistance.

Propylene, which is a raw material for the coating composition of the present invention
α-olefin copolymer is an α-olefin copolymer mainly composed of propylene.
It is a copolymerization of olefins, and random copolymerization is preferable to block copolymerization. Examples of the α-olefin component include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, etc., and two or more types of these may be copolymerized. . Among these, ethylene or 1
-Butene is preferred. Also, the proportion of propylene component is 5
The amount is preferably from 5 to 85 mol%; if it is less than 55 mol%, the adhesion to polypropylene will be poor, and if it is more than 85 mol%, the resulting coating composition will have poor solubility in solvents.

Examples of the α-unsaturated dicarboxylic acid or its acid anhydride to be graft-copolymerized to the propylene-α-olefin copolymer include maleic fumaric acid, itaconic acid, citraconic acid, allylsuccinic acid, mesaconic acid, aconitic acid,
and acid anhydrides thereof. The amount of α-unsaturated unsaturated dicarboxylic acid or its acid anhydride to be graft copolymerized is preferably from 0.1 to 15% by weight; if it is less than 0.1% by weight, the resulting resin will have poor adhesion to the top coat, and will not adhere to the epoxy resin. The effect of cross-linking will be reduced,
If it exceeds 15% by weight, not only the adhesion to polypropylene becomes poor, but also the grafting efficiency becomes poor, which is uneconomical. Particularly preferred is 1 to 10% by weight. Also,
The molecular weight of the resin obtained by graft copolymerizing α-unsaturated unsaturated dicarboxylic acid and its acid anhydride is 3,000 to 35,000.
is preferable, and if it is less than 3,000, the condensing force will be insufficient, resulting in poor adhesion, and if it is more than 35,000, the solubility in solvents and compatibility with other resins will be poor, which is not preferable. The molecular weight can be controlled within this range by controlling the molecular weight of the raw materials and the conditions for carrying out the graft reaction. Note that the molecular weight here refers to the weight average molecular weight,
It can be measured by GPC (gel permeation chromatography).

The method of graft copolymerizing a propylene-α-olefin copolymer with an αβ-unsaturated dicarboxylic acid or its acid anhydride is to heat-dissolve the propylene α-olefin copolymer in an organic solvent such as xylene, and then (solution method) or by heating and melting the propylene α-olefin copolymer above its melting point and reacting in the presence of a rancal generator (melting method). I can do it. In the solution method, it is preferable to use an aromatic solvent such as toluene or xylene as the organic solvent, and the reaction temperature is +00 to 180°C. This method has few side reactions and can obtain a homogeneous graft copolymer. It has the characteristic of being able to In the case of the melting method, a Banbury mixer, a kneader 9 extruder, etc. are used, and the reaction is carried out at a temperature above the melting point of the raw resin and below 300°C, and the reaction can be completed in the above-mentioned time period, which is easy to operate. can.

The radical generator used in the reaction can be appropriately selected from known radical generators, but organic peroxides are particularly preferred. Examples of organic peroxides include benzoyl peroxide, dicumyl peroxide, lauroyl peroxide, 2,5-dimethyl-2,5-di(1-butylperoquine)hexyne-3,di-l-butylperoxide (-butyl hydro Examples include peroxide, 1-butylperoxybenzoate, cumene hydroperoxide, and the like.

The compound or resin having two or more epoxy groups per molecule used in the present invention is preferably one having good compatibility with polyolefin, such as bisphenol A type or glycidyl ether type of polyhydric alcohol, such as ethylene glycol glycidyl ether, Propylene glycol glycidyl ether, glycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc.
Other materials having two or more epoxy groups in one molecule, such as cycloaliphatic epoxy resins obtained by oxidizing olefins with peracids and copolymers of glycidyl methacrylate, may also be used.

The blending ratio of α-unsaturated unsaturated dicarboxylic acid is a propylene-α-olefin copolymer (1) obtained by graft copolymerizing its acid anhydride and a compound or resin (2) having two or more epoxy groups per molecule. , weight ratio 100:0.
A range of 5 to 50 is desirable for practicing the present invention. (2) is 0
If it is less than 5, the curling resistance will not be sufficient, and if it exceeds 50, the adhesion to polypropylene will decrease. Furthermore, tertiary amines such as pyridine, isoquinoline, and quinoline are used to promote the crosslinking reaction between epoxy groups and carboxyl groups or acid anhydride groups.

It is also possible to add a catalyst such as NN-dimethylschiffhenylamine, triethylamine, hensyldimethylamine, 1,8-diazo-bicyclo-undecene-7, etc.
It can be added in an amount of 0.05% to 5% by weight based on 1).

The resin obtained in the present invention not only shows strong adhesion to polypropylene, but also has better solvent resistance and
Excellent gasoline resistance.

In addition, weather resistance, solubility in organic solvents, storage stability,
It also has good sprayability and compatibility with other resins. Therefore, it is suitable as a primer for painting or adhering polypropylene resin molded products. The composition of the present invention may be used as an organic solvent solution as it is, or may be kneaded with a pigment by a known method. As the organic solvent, it is preferable to use aromatic solvents such as toluene and xylene. As the pigment, inorganic pigments such as titanium oxide and carbon black, and other organic pigments can be used. It is preferable to dry the coating film between room temperature and 150°C to obtain a cured coating film. At this time, suitable top coats are, for example, urethane paints, melamine paints, epoxy paints, alkyd paints, and the like.

Furthermore, it is also possible to prepare a coating material by kneading the composition of the present invention, a coating resin, and a pigment, and directly coat it on a polypropylene resin molded article without using a primer. It can also be used as a coating agent for polypropylene films or as an ink resin.

[For production]

The coating composition for polypropylene resin of the present invention comprises a propylene-α-olefin copolymer graft-copolymerized with α-unsaturated dicarboxylic acid or its anhydride (1), and 2 or more per molecule. Since the main component is a compound having an epoxy group or resin (2), it has a good liquid state when dissolved in an organic solvent and has excellent coating properties, and also exhibits excellent adhesion to polypropylene resins. It also shows adhesion to polar resins such as top coats. Furthermore, since a cured film is formed through a crosslinking reaction between the carboxyl group or acid anhydride group (1) and the epoxy group (2), the film after application and drying has excellent solvent resistance and gasoline resistance. ing.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Production Example 1 In a three-day flask equipped with a stirrer, a cooling tube, and a dropping funnel, propylene-butene copolymer (propylene component 75 mol %, weight average molecular weight 65,000)]O
After heating and dissolving Og in 400 g of xylene, while stirring while maintaining the temperature of the system at 140 ° C, 10 g of maleic anhydride and 2 g of Ncumyl peroxy F were added dropwise over 2 hours each, and then for 3 hours. Made it react. After the reaction was cooled to room temperature, the reaction product was poured into a large amount of acetone for purification to obtain a graft copolymer with a graft amount of 58%.

When measuring the molecular weight by GPC, the weight average molecular weight is 2.
It was 7QQG. This was dissolved in toluene at a concentration of 20% by weight.

Production Example 2 Maleic anhydride was graft copolymerized in the same manner as Production Example 1 using the same raw materials as Production Example 1 to obtain a graft copolymer with a graft amount of 32%.

This was dissolved in toluene at a concentration of 20% by weight.

Production Example 3 Using a propylene-ethylene copolymer (propylene component 65 mol%) as a raw material, maleic anhydride was graft copolymerized in the same manner as in Production Example 1 to obtain a graft copolymer with a graft amount of 4.5%. Ta. This was dissolved in toluene at a concentration of 10% by weight.

Production Example 4 Using a propylene-ethylene-butene copolymer (propylene component 75 mol%) as a raw material, maleic anhydride was graft copolymerized in the same manner as Production Example 1 to obtain a graft copolymer with a graft amount of 52%. Ta. This was dissolved in toluene at a concentration of 20% by weight.

Example 1 To 350 g of a toluene solution of the composition obtained in Production Example 1, 828 g of epoxy resin (Epicor) was added. Made of oil-based shell epoxy)
15g of was added. Mix this with 30g of titanium oxide,
After dispersing the pigment in a sand mill for 1 hour, it was diluted with toluene to an appropriate viscosity and spray coated onto a polypropylene plate whose surface had been degreased with toluene. After being left to dry at room temperature for about 10 minutes, a two-component urethane paint was spray applied and left to stand at room temperature for 10 minutes. Next, it was force-dried at 80° C. for 30 minutes using a hot air dryer.

After the obtained coated board was left at room temperature for 7 days, the coating film was tested. The results are shown in Table 1.

Example 2 To 350 g of the toluene solution of the composition obtained in Production Example 1, an epoxy resin (Denacol EX-61) was added. Manufactured by Nagase Kasei) 1
0g was blended. This was mixed with 30 g of titanium oxide, and the pigment was dispersed in a sand mill for 1 hour. As a reaction enhancer, 7 g of a 10% by weight xylene solution of an amine catalyst (U-Cat-3nin-\0102. manufactured by San-Apro) was added.

This was subjected to the same operation as in Example 1 to obtain a coated plate. The test results are shown in Table 1.

Examples 3 to 5 15 g of Epicote 828 was added to 350 g of a toluene solution of the composition of Production Examples 2 to 4, the pigment was dispersed in the same manner as in Example 1, and a painted board was prepared in the same manner as in Example 1. did. The test results are shown in Table 1.

Comparative Example 1 Composition obtained in Production Example 1 (20% by weight toluene solution)
350 g of titanium oxide were mixed with 30 g of titanium oxide, and the pigment was dispersed for 1 hour using Santo Mill, diluted with toluene to an appropriate viscosity, and spray coated on a polypropylene plate whose surface had been degreased with toluene. After being left to dry at room temperature for about 10 minutes, a two-component urethane paint was spray applied and left to stand at room temperature for 10 minutes. Next, use a hot air dryer to
It was force-dried at C for 30 minutes. The obtained painted board was heated at room temperature for 7
The coating film was tested after being allowed to stand for several days. The results are shown in Table 1.

Comparative Example 2 A propylene-butene copolymer (propylene component: 75 mol %, weight average molecular weight: 65,000) was thermally degraded to obtain one having a weight average molecular weight of 24,000. This was made into a 10% toluene solution, 8 g of Epicote 828 was blended with 350 g of this solution, titanium oxide was dispersed in the same manner as in Example 1, and a coated plate was prepared in the same manner as in Example 1. The test results are shown in Table 1.

Chapter 1 Table The test method is as follows.

Appearance of paint film The appearance of the coating film was visually observed.

Adhesive Make a cut on the surface of the coating film with a cutter to reach the substrate.
100 goblets were made at mm intervals, a cellophane adhesive tape was adhered thereto, and the tape was peeled off in a 180 degree direction, and the number of remaining goblets was counted.

Cuts were made on the surface of the kalin-resistant coating film to reach the substrate, and after immersion in regular kalin for 24 hours, the condition of the coating film was visually observed.

Moisture Resistance After being left in an atmosphere of 50° C. and relative humidity of 95% or higher for 10 days, a peel test was performed using cellophane adhesive tape.

Water Resistance After being immersed in warm water at 50°C for 10 days, a peel test was conducted using cellophane adhesive tape.

〔Effect of the invention〕

The better the resin obtained in the present invention is in solvent resistance and gasoline resistance, the better its adhesion to polypropylene, solubility in organic solvents, storage stability, sprayability, and compatibility with other resins. . For this reason, it is suitable as a primer for painting and adhering polypropylene resin molded products, and exhibits strong adhesion to both the base material and top coat.
Even in cases where severe performance is required, such as in automotive applications, coating films with excellent physical properties can be obtained.

Furthermore, it is possible to prepare a paint using the resin of the present invention and apply it to polypropylene resin without a primer, and it can also be applied as a coating agent for polypropylene film.

Procedure auxiliary device (spontaneous) Display of the case dated December 1990, 1990 Patent Application No. 251544 Name of the invention Relationship with the person who amends the coating composition for polypropylene resin Patent applicant address Chiyoda-ku, Tokyo Marunouchi-chome 4-5 name
Name (234) Sanyo Kokusaku Pulp Co., Ltd. 4, Agent Address: 16 Kanda-kita Jomono-cho, Chiyoda-ku, Tokyo 101 Ei Building 3rd Floor Contents of Amendment The following matters in the specification of this application are corrected.

Note 1: "Propylene" from the last line of page 5 to the first line of page 6 of the specification
Corrected the text to read "propylene".

2. On page 5 of the specification, line 1) It says "condensing force" Corrected to "cohesion."

3. On page 9, lines 15 and 16 of the specification, "glycerol polyglycidyl ether" was corrected to "glycerol polyglycidyl ether."

4. On the same page, lines 16-17 It says "Sorbitol polyglycidyl ether" Corrected to "Sorbitol polyglycidyl ether."

5. Line 1 of page 5 of the specification It says "to use" Corrected to "use".

Claims (3)

[Claims] (1) A propylene-α-olefin copolymer (1) obtained by graft copolymerizing 0.1 to 15% by weight of α,β-unsaturated dicarboxylic acid or its acid anhydride;
A cured film is formed by a crosslinking reaction between the carboxyl group or acid anhydride group of (1) and the epoxy group of (2), the main component being a compound or resin (2) having at least 3 epoxy groups. Coating composition for polypropylene resin. (2) A propylene-α-olefin copolymer (1) obtained by graft copolymerizing 0.1 to 15% by weight of α,β-unsaturated dicarboxylic acid or its acid anhydride;
Compound or resin (2) having 1 or more epoxy groups
The coating composition for polypropylene resin according to claim 1, wherein the weight part ratio of (3) The molecular weight of the propylene-α-olefin copolymer obtained by graft copolymerizing 0.1 to 15% by weight of α,β-unsaturated dicarboxylic acid or its acid anhydride is 3,000 to 35,000. The coating composition for polypropylene resin described above.