JPH03258845A - Polypropylene resin composition and molded article thereof - Google Patents

Abstract

PURPOSE:To obtain the subject composition exhibiting excellent coating film adhesivity without pretreating a molded article by compounding a polypropylene, an ethylene-alpha-olefin copolymer and a specific carboxylic acid. CONSTITUTION:The objective composition is produced by the heat-treatment of a composition composed of a polymer mixture of a polypropylene and an ethylene-alpha-olefin copolymer and containing an unsaturated carboxylic acid having at least one hydroxyl group and/or a derivative of the carboxylic acid and a radical generator. The compounding ratio of polypropylene to the ethylene-alpha-olefin copolymer is 90/10 to 70/30. The ethylene-alpha-olefin copolymer is preferably a composition of propylene and ethylidenenorbornene having an ethylene content of <=25%.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a polypropylene (PP) resin composition and a molded article thereof. It has improved coating properties (Wke adhesion), and is suitable for automobile bumpers as shown in FIG. 1, as well as automobile exterior crystals (molded products) such as side moldings, spoilers, and mudguards.

A list of abbreviations used in the following explanation is shown below.

PP...polypropylene, EPR...ethylene-α-olefin copolymer, EPM...ethylene-propylene copolymer, EPDM
...Ethylene-propylene-nonconjugated diene terpolymer, MFR...Melt flow rate (separate resin material is 19
g of resin material extruded in 10 minutes from an orifice with a diameter of 2.1 mm when subjected to a force of 218 (Ig) at 0°C
number>, M L *, (100°C)... Viscosity unit measured with a Mooney shear disk viscometer (large disk, preheated 1oo"Cx
1 minute, instrument indication 4 minutes after the start of rotation),
The compounding unit is the I weight wheel unless otherwise specified.

<Prior Art> PP resin compositions are widely used as general-purpose plastics because their molded products have excellent mechanical properties, chemical resistance, etc., good moldability, and are inexpensive. However, since PP is a non-polar polymer, it is generally used in paints (
The coating component is mainly a polar polymer. ), and it was necessary to perform pre-treatments such as brimer treatment and plasma treatment before painting. These pre-treatments are cumbersome and reduce the productivity of painting operations.

For this reason, a polymer mixture of PP and EPR is used as a molded product material that exhibits good paintability even without pretreatment such as brimer treatment, and an unsaturated carboxylic acid and/or its derivative is used as a radical generator. A PP-based resin composition which is a heat-treated product containing the same has been proposed (see JP-A No. 62-280287, etc.).

<Problems to be Solved by the Invention> However, as far as the inventors have tested and studied, the molded product made of the PP resin composition disclosed in the above publication has sufficient paint film adhesion (paint adhesion). I found out that the gender) is IFJIl and ugly. That is, unsaturated dicarboxylic acids such as those exemplified in the above publications, such as maleic anhydride, which is said to be the most desirable, are sufficient! 1! Adhesion could not be obtained (see Comparative Example 4 in Table 1).

In view of the above, the present invention provides sufficient coating without pre-treatment of molded products! pppp that can achieve adhesion
The purpose of the present invention is to provide a resin composition and a molded article thereof.

<Means for Solving the Problems> In order to solve the above problems, the present inventors made earnest efforts in development, and as a result, molded with a PP resin composition modified using specific carboxylic acids. The molded product should be coated with sufficient coating 1.
1! They found that it has adhesive properties, and came up with a PP-based resin composition and a molded article thereof having the following structure.

The invention according to the first claim is a pp-based resin composition which is a heat-treated product of a polymer mixed system of PP and EPR, which contains an unsaturated carboxylic acid and/or a derivative thereof together with a radical generator, The unsaturated carboxylic acid and its derivatives are characterized in that they have at least one hydroxyl group.

The invention according to the second claim is a pp-based molded product, in which the molded product main body is molded with the resin composition according to the first claim, and required parts of the molded product main body are painted.

(1) The resin composition of the present invention is a heat-treated product of a polymer mixture of PP and EPR containing an unsaturated carboxylic acid and/or a derivative thereof together with a radical generator. ■Prescription of polymer components: The blending ratio of PP and EPR is PP/EPR=90/10.
~70/30 (preferably 60/4 Q~80
/20). If the blending ratio of EPH is too small, it will be difficult to improve the paintability of the molded product. If the blending ratio of EPR is too high, the rubbery properties of the molded product will become too strong and the PP
It is difficult to call it a resin composition.

a) The above-mentioned PP is not particularly limited, but preferably a crystalline PP$ autopolymer and/or a crystalline block copolymer containing 25% or less of an ethylene component.

b) The above EPR is a concept that includes both EPM and EPDM. The weight fraction of each component is ethylene/α-olefin/non-conjugated diene=0.2-0.810.2-G
, 810-0.1 is desirable.

The α-olefin used here has 3 to 1 carbon atoms.
For example, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, etc. can be mentioned, and propylene is preferable. The above α-olefin may be used alone or 2f! The above can be used in combination.

Examples of the non-conjugated diene include ethylidenenorbornene, cyclopentadiene, 1,4-hexadiene, methylenenorbornene, etc., but ethylidenenorbornene is preferable.

(2) Organic radical generator: The organic radical generator mainly functions to graft-polymerize unsaturated carboxylic acid onto each of the polymer components described above. The blending amount is generally determined in relation to the type and blending amount of the unsaturated carboxylic acid, and the molar ratio of unsaturated carboxylic acid/radical generator is 15 to 85. Usually, per 100 parts of the polymer component. 0.0
1 to 0.5 parts.

As the radical generator that can be used in the present invention, conventional ones such as the following organic peroxides and azo compounds can be used, but inorganic peroxides such as persulfates can also be used. Among them, 1,3-bis(t-butylperoxyisopropyl)benzene is preferred.

2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,3-bis(t-butyl) peroxyisopropyl)benzene, 2,2'-bis(t-butylperoxy)-p-diisopropylbenzene, dicumyl peroxide, di-t-butyl peroxide, t-butyl benzoate, dibenzoyl peroxide, azobisisobutyronitrile.

(2) Preparation of the resin composition involves blending the above polymer component with an unsaturated carboxylic acid together with the above radical generator, using an extruder or a mixer such as a Banbury kneader at 170 - 280°C x 0.2 - This is carried out by heat treatment for 30 minutes.

(2) A characteristic feature of the present invention is that the unsaturated carboxylic acid and its derivative have at least one hydroxyl group (hereinafter referred to as specific unsaturated carboxylic acids).

■The blending amount of this specific unsaturated carboxylic acid is the required coating 11! Although it varies depending on the adhesion and the mechanical properties (rigidity, etc.) of the molded product, 01 to 1
It will be 0 copies. If it is less than 0.1 part, it is not possible to improve the coating adhesion of the molded product, and if it exceeds 10 parts, it is not desirable because it adversely affects the physical properties (rigidity, impact strength, surface gloss, etc.) of the molded product.

■Specific unsaturated carboxylic acids that can be used include the following.

a) Alkyl alcohol N1II form of acid amide...N
- Methyloacrylamide, etc., b) Polyol ester of acrylic acids...2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, etc., C) Hydroxy acid...hydracrylic acid, etc. (3) Preparation and molding of molding material : The pp-based resin composition having the above structure may contain antioxidants, heat stabilizers, ultraviolet absorbers, colorants, inorganic fillers (
Auxiliary materials such as calcium carbonate, talc, glass fiber) are blended into the molding material (usually a pellet) through the heat treatment process described above.

Using the molding material, a molded product (for example, a bumper as shown in FIG. 1) is obtained by injection molding, extrusion, or the like.

(4) Painting of molded products: The molded products thus molded are usually washed with a chlorinated organic solvent such as trichlorethylene, and then treated with a brimer if necessary. Paint with plastic paint. Among the above-mentioned paints, urethane-based paints are preferred from the viewpoint of film performance and film adhesion.

<Actions and Effects of the Invention> The PP-based resin composition of the present invention is a heat-treated product that is a polymer mixture of PP and EPR and contains an unsaturated carboxylic acid and/or a derivative thereof together with a radical generator. In the PP resin composition, by using an unsaturated carboxylic acid and its derivative having at least one hydroxyl group, the following actions and effects can be achieved.

The molded article body made of the PP resin composition of the present invention has sufficient paint film adhesion to a paint film made of a general-purpose plastic paint without pretreatment, as shown in the Examples below.

<Examples/Comparative Examples> The following are examples and comparative examples conducted to confirm the effects of the present invention.
A comparative example will be explained.

(1) Preparation of molding material: The mixture of each compounding recipe shown in Table 1 was melt-mixed using a co-directional twin-screw extruder, cylinder inlet temperature: 150°C,
Outlet temperature: 200℃, screw rotation speed: 200rp■
), a pellet-shaped injection molding material was prepared.

The specific examples and physical properties of each compound used in the formulation are as follows.

PP..."Highball J-300P" manufactured by Mitsui Petrochemical ■, MFR: 1.4 g/10 win.

EPM...“EP 911P” Made by Japan Synthetic Rubber ■, M
L *h4 (100℃) = 15, EPDM..."EP 57P" made by Japan Synthetic Rubber ■, radical generator..."Parkadox 14" Akzo■
(2) Molding and painting: Injection using the molding material prepared above. Molding (conditions, inlet temperature =
170℃, outlet temperature = 200℃), and the molded product (4
0x 1fOX 2) was obtained.

After degreasing the molded product with a chlorinated organic solvent (trichlorethylene) and applying a urethane paint (film thickness: 30 μm)
), each sample was baked under the conditions of 90°C x 40 minutes.

The paint used is "R278" manufactured by Nippon B Chemical Co., Ltd.
A two-component product consisting of (base agent) and "R271" (curing agent) was used.

(3)! ! ! Membrane adhesion test: For each sample prepared above, the substrate test (1-
100 squares, transparent adhesive cellophane tape)
The number of peeled pieces was counted.

From Table 1 showing the test results, molded products made of the materials of each example (resin compositions of the present invention) using specific carboxylic acids as unsaturated carboxylic acids, other than maleic anhydride, diacetone acrylamide, etc. It can be seen that the molded articles made of resin compositions using unsaturated carboxylic acids (Comparative Examples 4 and 5) exhibit much better adhesion to Coating 8I.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an automobile bumper showing an example of a molded product to which the present invention can be applied. Patent applicant Toyoda Gosei Co., Ltd. Figure

Claims (1)

[Scope of Claims] 1. Polypropylene which is a polymer mixture of polypropylene and an ethylene-α-olefin copolymer and is a heat-treated product containing an unsaturated carboxylic acid and/or its derivative together with a radical generator. A polypropylene resin composition, characterized in that the unsaturated carboxylic acid and its derivatives have at least one hydroxyl group. 2. Molding with a polypropylene resin composition that is a heat-treated product of a polymer mixture of polypropylene and an ethylene-α-olefin copolymer that contains an unsaturated carboxylic acid and/or its derivative together with a radical generator. A polypropylene molded product in which the product body is molded and required parts of the molded product body are painted, characterized in that the unsaturated carboxylic acid and its derivatives have at least one hydroxyl group. Molding.