JPH04114072A - Coating composition for polyolefin based resin - Google Patents

Abstract

PURPOSE:To obtain the title composition containing a resin obtained by subjecting a propylene-butene copolymer to graft copolymerization with alpha,beta-unsaturated dicarboxylic acid (derivative) at a specific amount and having excellent adhesion to polyolefin and solubility in an organic solvent. CONSTITUTION:The aimed composition obtained by subjecting a propylenebutene copolymer (preferably containing 55-85mol% propylene component) to graft copolymerization with 0.1-15wt.%, preferably 1-10wt.% alpha,beta-unsaturated dicarboxylic acid (derivative) (e.g. maleic acid, fumaric acid or itaconic acid) and containing a resin having 3000-35000, preferably 5000-30000 molecular weight.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The purpose of the present invention is to improve the adhesion when painting the surface of a polyolefin resin molded product or when bonding another base material to a polyolefin resin. The coating group used in the test.

[Conventional technology]

Polyolefin resins such as polypropylene have excellent properties and are inexpensive, so they are used in large quantities in home appliances, automobile parts, and the like.

However, since polyolefin resins are non-polar, they have the disadvantage of being difficult to paint or adhere to.

In order to solve these drawbacks, conventionally, the surface of polyolefin resin molded products is treated with flame treatment, corona discharge treatment, plasma treatment, etc. to improve adhesion before painting or adhering the polyolefin resin molded products. However, the processing operations are cumbersome and it is difficult to uniformly process objects with complicated shapes, making them impractical.

In addition, primer compositions containing chlorinated modified polyolefin 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 the common drawbacks of excellent adhesion to polyolefins and inferior weather resistance and solvent resistance, and their uses are extremely limited.

On the other hand, various non-chlorinated primer compositions that are adhesive to polyolefins have been proposed. For example, Japanese Patent Publication No. 62-21027 discloses a primer composition in which maleic acid or its anhydride is graft copolymerized to a propylene-ethylene copolymer. There are disadvantages in that particulate undissolved matter is generated, which causes unevenness in the painted coating film, significantly impairing the appearance, causing variations in adhesion, and extremely deteriorating spray applicability. Also, in JP-A-58-185655, propylene-
A coating composition containing an α-olefin copolymer graft-copolymerized with an α,β-unsaturated dicarboxylic acid is disclosed, but the examples only show examples of propylene-ethylene copolymers. In fact, it has almost no practical use because it has the same drawbacks as the above-mentioned resin and lacks compatibility with other resins.

(Problems to be Solved by the Invention) As mentioned above, is it realistic to apply primer treatment to paint or bond polyolefin? Both techniques have drawbacks, such as poor adhesion to polyolefin, Weather resistance, solvent resistance, solubility of resin in solvents, storage stability.

There was no product that satisfied the required performance such as spray applicability and compatibility with other resins in a well-balanced manner. The object of the present invention is to provide a coating composition that can solve these problems and improve the paintability and adhesion of polyolefin resins.

[Means to solve the problem]

In order to achieve the above object, the present invention was achieved as a result of various studies. That is, propylene-butene copolymer has α, β-
0.1 to 1 unsaturated dicarboxylic acid or its derivative
The above object has been achieved by a coating composition for a polyolefin resin, which is characterized in that it contains a 5% by weight graft copolymerized resin having a molecular weight of 3,000 to 35,000.

Propylene, which is a raw material for the coating composition of the present invention
The butene copolymer is a copolymer of propylene as a main component and butene-1, and random copolymerization is more preferable than block copolymerization. The proportion of propylene component is 55 to 8
The amount is preferably 5 mol %, and if it is less than 55 mol %, the adhesion to polyolefin will be reduced, and if it is more than 85 mol %, the resulting resin will have poor solubility in the solvent. Further, it may contain components other than propylene and butene-1 within a range of 10 mol% or less.

α graft copolymerized to propylene-butene copolymer,
β-unsaturated dicarboxylic acid or its derivative means α, β
- In addition to unsaturated dicarboxylic acids, it refers to acid anhydrides of α,β-unsaturated dicarboxylic acids and their esters, such as maleic acid.

Examples include fumaric acid, itaconic acid, citraconic acid, allylsuccinic acid, mesaconic acid, aconitic acid, acid anhydrides thereof, and alkyl esters thereof. The amount of α, β-unsaturated dicarboxylic acid or its derivative to be graft copolymerized is preferably 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, % or more, not only the adhesion to the polyolefin deteriorates but also the grafting efficiency deteriorates, which is uneconomical. Particularly preferred is 1 to 10% by weight. Further, the molecular weight of the resin obtained by graft copolymerizing α,β-unsaturated dicarboxylic acid or its derivative is 3000 to 350.
0θ is preferable; if it is less than 3000, the cohesive force will be insufficient and the adhesion will be poor; if it is more than 3511, the solubility in solvents will be poor (and the compatibility with other resins will be poor, which is not preferable. Particularly preferably 8000 or 3000G
It is. 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. In addition, the molecular weight here refers to a weight average molecular weight, and can be measured by GPC (gel permeation chromatography).

The method of graft copolymerizing α,β-unsaturated dicarboxylic acid or its derivatives to propylene-butene copolymer is to heat-dissolve the propylene-butene copolymer in an organic solvent such as xylene and react in the presence of a radical generator. How to do it (
This can be carried out by any known method, such as a solution method) or a method in which a propylene-butene copolymer is heated to a temperature higher than its melting point and reacted in the presence of a radical generator (melt method). 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 100°C.
This method is carried out at 180° C., and is characterized by having few side reactions and being able to obtain a homogeneous graft copolymer. In the case of the melting method, a Banbury mixer-kneader 1 extruder or the like is used, and the reaction is carried out at a temperature above the melting point of the raw material resin and below 300°C, and the operation is simple and the reaction can be completed in a short time.

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, and lauroyl peroxide.

2.5-dimethyl-2,5-di(1-butylperoxy)hexyne-3,di-t-butyl peroxide.

Examples thereof include 1-butyl hydroperoxide, 1-butyl peroxybenzoate, and cumene hydroperoxide.

The resin obtained in the present invention has excellent adhesion to polyolefin, weather resistance, solvent resistance, solubility in organic solvents,
It has good storage stability, spray applicability, and compatibility with other resins, and is suitable as a primer for painting or adhering polyolefin resin molded products. An organic solvent solution of the composition of the present invention may be used as it is, or it 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. 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 the polyolefin resin molded article without using a primer. It is also excellent as a coating agent for polyolefin films, and can also be used as an ink resin.

Also, olefin resins and acrylic resins.

Other resins such as epoxy resins, urethane resins, and alkyd resins may be added, and additives such as ultraviolet absorbers and antioxidants may be added as necessary.

Note that the polyolefin resin in the present invention includes polyethylene, polypropylene, and ethylene-propylene copolymer.

Although it refers to ethylene-propylene-diene copolymer, etc., the coating composition of the present invention can also be applied to plastics other than polyolefin resins.

[For production]

The coating composition for polyolefin resins of the present invention uses a propylene-butene copolymer as a raw material and graft-copolymerizes α,β-unsaturated dicarboxylic acid or its derivatives, so it has excellent adhesion to polyolefins. , also shows good adhesion to polar resins. Furthermore, the modification of the present invention improves the solubility in organic solvents, and can also satisfy the performance required as a coating composition.

〔Example〕

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

Example 1 In a three-day flask equipped with a stirrer, a cooling tube, and a dropping funnel, 100 g of propylene-butene copolymer (propylene component 75 mol%, weight average molecular weight 65,000) was dissolved in 400 g of xylene by heating, and then the system temperature 14
While maintaining the temperature at 0° C. and stirring, 10 g of maleic anhydride and 2 g of dicumyl peroxide were each added dropwise over 2 hours, followed by a reaction for 3 hours. After the reaction, the reaction product was cooled to room temperature and purified by pouring it into a large amount of acetone to obtain a graft copolymer with a graft amount of 5.8%.

When the molecular weight was measured by GPC, the weight average molecular weight was 27.
It was 000. This was dissolved in toluene at a concentration of 20% by weight, and the liquid properties and storage stability were examined.

The results are shown in Table 1.

Examples 2 to 6 A graft reaction of a propylene-butene copolymer was carried out in the same manner as in Example 1 to obtain a resin for a coating composition.

Table 1 shows the proportion of propylene in the raw material, the type and amount of grafted material, the properties and storage stability of the resulting toluene solution of the resin.

Comparative Examples 1 to 3 Modified resins were obtained in the same manner as in Example 1 using the raw materials and conditions shown in Table 1. Table 1 shows the properties and storage stability of the toluene solution of the obtained resin.

Note that storage stability was determined by leaving a 20% toluene solution at room temperature for 3 months and observing the state of the solution.

Good: No change; Bad: A large amount of insoluble matter was generated.

Examples 7 to I2 350 g of the resin obtained in Examples 1 to 6 (20% by weight toluene solution) and 30 g of titanium oxide were mixed and mixed in Santo Mill.
After the pigment was dispersed for a period of time, it was diluted with toluene to an appropriate viscosity and sprayed 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, use a hot air dryer to dry at 80℃ for 30 minutes.
Force dry for a minute. The resulting coated board was left at room temperature for 7 days, and then the coating film was tested. The results are shown in Table 2.

Comparative Examples 4 to 6 Coated plates were prepared using the resins obtained in Comparative Examples 1 to 3 (10% by weight toluene solutions) in the same manner as in Examples 7 to I2, and the coating films were tested. The results are shown in Table 2.

The test method is as follows.

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

Adhesive Make slits on the surface of the paint film that reach the substrate with a cutter to make 100 goblets at 1-hole intervals, then stick cellophane adhesive tape on top of the cut and peel it off in a 180 degree direction to remove the remaining gobangs. I counted the numbers.

A cut was made on the surface of the gasoline-resistant coating film to reach the substrate, and after immersion in regular gasoline for 4 hours, the condition of the coating film was visually observed.

Humidity Resistance After being left in an atmosphere of 50° C. and relative humidity of 95% or higher for 10 days, the condition of the coating film was visually observed.

Water Resistance After being immersed in warm water at 50°C for 10 days, the state of the coating film was visually observed.

〔Effect of the invention〕

The resin obtained in the present invention not only has excellent adhesion to polyolefins, but also has good solubility in organic solvents, especially in aromatic solvents such as toluene and xylene. % or more. By using such a resin with good solubility as a coating composition, it is possible to obtain a smooth coating film when used as a paint without forming particulate undissolved substances during storage. In addition, since the spray coating property is good, the coating is uniformly applied, and as a result, there is no variation in adhesion and stable performance can be obtained. In addition, it has good compatibility with other resins and has a wide range of applications as a coating composition.

Claims (2)

[Claims] (1) 0.1 to 15% by weight of α,β-unsaturated dicarboxylic acid or its derivative in propylene-butene copolymer
Graft copolymerized with a molecular weight of 3000 to 350
A coating composition for a polyolefin resin, characterized by containing a resin having the following properties: (2) The coating composition for a polyolefin resin according to claim 1, wherein the propylene component of the propylene-butene copolymer is 55 to 85 mol%.