JPH0812788A - Coated composite resin molding - Google Patents

Abstract

PURPOSE:To obtain a composite resin molding covered with a coating having sufficient adhesion to the molding and sufficient chipping resistance even when the molding has not undergone cleaning with 1,1,1-trichloroethane as a pretreatment. CONSTITUTION:The coated molding comprises an integrally molded composite resin comprising a rigid PP part and a soft SEBS part and, formed on the molded resin, a coating comprising an undercoat film and a topcoat film formed thereon, the undercoat film comprising as a major component a noncrystalline ethylene/propylene copolymer containing polar groups incorporated therein and having a weight-average mol.wt. of 90,000-140,000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a PP-based material hard portion and SE.
The present invention relates to a coated composite resin molded article in which an upper coating film is formed via a undercoat coating film on a composite resin molded article integrally formed with a BS material soft part.

In particular, the present invention is suitable for exterior parts for automobiles (painted composite resin molded products) such as over fenders, lower garnishes, mudguards, etc., which are required to have chipping resistance.

Here, the description will be given by mainly taking the over fender as an example, but the present invention is not limited to this.

The main abbreviations of the polymers used in the present specification are as follows.

PP ... Polypropylene, PS ... Polystyrene, Chlorinated PO ... Chlorinated polyolefin Chlorinated PP ... Chlorinated polypropylene EPR ... Amorphous ethylene propylene copolymer SEBS ... PS-Polyethylene / Polybutylene-PS structure styrene-based thermoplastic Elastomer.

[0006]

2. Description of the Related Art Generally, an overfender is a separate cushioning material in which a main body having a mounting portion to a sheet metal of a vehicle body is molded by FRP, and a main body which is a contact portion with the sheet metal is molded of soft polyvinyl chloride or the like. It was the structure which attached.

However, since the overfender having the above-mentioned structure has a problem that it is difficult to recycle and the main body and the cushioning material need to be separately molded and attached, as shown in FIG. It is conceivable to integrally form the shock absorbing portion (protector portion) 13 and the shock absorbing portion (protector portion) 13. In addition, in the illustrated example, 11
Reference numeral a is an attachment portion to the vehicle body sheet metal 15, and reference numeral 17 is an attachment clip.

The present inventors formed the fender main body (hard portion) 11 with a PP material which is excellent in chemical resistance, water resistance, moldability, weather resistance, etc., and is lightweight and inexpensive. An attempt was made to form the buffer portion 13 from a SEBS material that can be integrally molded with the PP material and has similar characteristics.

However, since the PP material is inferior in scratch resistance and weather resistance, it cannot be used as an over fender as it is as a molded product. Therefore, a non-yellowing urethane resin is used for surface modification also for decoration. It is necessary to form the coating film 19 with a paint having excellent weather resistance and scratch resistance, such as a system paint.

However, since both the PP-based material and the SEBS material are non-polar materials, they do not adhere to the polar resin-based coating material as described above only by ordinary pretreatment.

Therefore, for example, after steam cleaning with 1,1,1-trichloroethane (TCE) (mainly for the purpose of surface roughening), after applying an undercoat paint having a reaction adhesive property with an overcoat film, It is conceivable to apply a top coat (see Japanese Patent Publication No. 3-22895).

[0012] However, TCE has a problem of environmental pollution and will be unusable in the future (completely abolished in 1995).
It cannot be used because it swells the SEBS material.

Therefore, Japanese Patent Laid-Open No. 4-363372 / 5-9
T containing a modified olefin-based elastomer having the following temperature structure disclosed in Japanese Patent No. 7937, etc. as a coating film main component
It is conceivable to use an undercoat paint (primer composition) that does not require CE.

"A propylene / butene / ethylene terpolymer, a modified copolymer obtained by graft-copolymerizing at least one selected from monoolefin dicarboxylic acid and its anhydride, and a primer composition containing an organic solvent. Stuff."

[0015]

However, as a result of investigations by the present inventors, in the case of this primer, it was found that it is difficult to impart sufficient base material adhesion and pitting resistance to the top coat film.

In view of the above, the present invention is a composite resin molded article in which a hard portion of a PP material and a soft portion of a SEBS material are integrally molded, and a sufficient coating film can be obtained without TCE cleaning as a pretreatment. It is intended to provide a coated composite resin molded article having adhesion and pitting resistance.

[0017]

[Means for Solving the Problems]

(1) The present invention according to claim 1 solves the above problem by the following configuration.

A coated composite resin molded article, in which a hard coating portion of a PP-based material and a soft portion of an SEBS material are integrally molded, and a top coating film is formed on the composite resin molded article via an undercoat coating film, The main coating film element of the undercoat coating film is composed of modified EPR, and the EPR has a weight average molecular weight of 90,000 to 140,000.

(2) The present invention according to claim 3 is to solve the above problems by the following constitution.

A coated composite resin molded article in which a hard coating portion of a PP-based material and a soft portion of a SEBS material are integrally molded, and a top coating film is formed on the composite resin molded article via an undercoat coating film, The main coating film element of the undercoat coating film is composed of a mixture of modified EBR and chlorinated PO, and the EPR has a weight average molecular weight of 90 to 140,000.

[0021]

[Detailed description of means]

(1) A prerequisite is a coated composite resin molded product in which a hard coat part of a PP-based material and a soft part of a SEBS material are integrally molded, and a top coat film is formed through a base coat film on the composite resin molded product. And

Examples of the PP material include PP homopolymer, PP copolymer, glass fiber-containing PP, rubber mixed PP and the like. The physical properties of the hard portion are usually flexural modulus: 1176 to 2646 MPa (1
2000-27,000 kgf / cm ² ), tensile strength: 11.8
˜24.5 MPa (120-250 kgf / cm ² ), hardness (Rockwell): 35-80R.

As the SEBS material, it is preferable to use not only SEBS alone but also a PP mixed material to which oil is appropriately added. The physical properties of the hard part are usually tensile strength: 2.94 to 19.6 MPa (30 to 200 kgf / cm
² ), hardness (JIS H _S (A)): 40 to 99, elongation: 30
0 to 950%.

Examples of the resin coating used for the top coating film (top coating) include urethane resin type, acrylic resin type, epoxy resin type, melamine resin type, guanamine resin type, unsaturated polyester type, urea resin type and the like. it can.

(2) In the present invention according to claim 1, the coating film main element of the undercoating film is a modified EPR, and the weight average molecular weight of the EPR is 90 to 140,000.

The modified EPR is a polar group-introduced product of an amorphous ethylene propylene copolymer (EPR).

This EPR is usually a binary polymer of ethylene / propylene, but it may be a terpolymer containing an α-olefin such as butene as the third component. Also,
The weight ratio of ethylene / propylene is 70/30 to 50 /
50, preferably around 60/40.

When the weight average molecular weight of EPR is less than 90,000,
Difficult to obtain adhesion and chipping resistance to the substrate, 1
If it exceeds 30,000, it is difficult to obtain the practical fluidity of the coating material and the leveling property of the coating film.

Incidentally, the weight average molecular weight of the propylene / butene / ethylene terpolymer described in the above-mentioned JP-A-5-97937 has a weight average molecular weight of 3000 to 7000.
0.

Here, the EPR is usually Tg (glass transition temperature) -70 to -30 ° C, preferably -50 to -35 ° C, from the viewpoint of coating film elongation, cold resistance, pitting resistance and the like.
Use one.

Examples of the introduced polar group include a carboxyl group, an epoxy group, a hydroxyl group and the like.
Particularly, a carboxyl group is desirable. The introduction of the carboxyl group is carried out in the same manner as described in JP-A-4-363372 mentioned above by dicarboxylic acids and acid anhydrides thereof (acryl metacinnamic acid, cretonic acid, maleic acid, maleic anhydride, itacone). At least one compound obtained from an acid or the like) is graft-polymerized by a conventional method. The introduction rate of the carboxyl group is usually 1 to 10%, preferably
3-6%. If the introduction ratio of the carboxy group is too small, it is difficult to obtain the adhesion to the top coating film, and even if it exceeds 10%, further improvement in the adhesion to the top coating film cannot be expected.

The introduction of the polar group has the function of increasing the compatibility with the chlorinated PO component of the invention of claim 3 in addition to the function of the coating film adhesion.

(3) In the present invention according to claim 3, the main coating film element of the undercoat film is composed of a mixture of modified EPR and chlorinated PO, and the weight average molecular weight of EPR is 90 to 140,000.

The modified EPR is as described in (2) above. Here, as the chlorinated PO, chlorinated PE, chlorinated P
P, chlorosulfonated PE, chlorosulfonated PP and the like can be mentioned. Chlorinated PP is particularly preferable. Usually, those having T _{g of} 20 to 65 ° C., chlorination degree of 5 to 40% and weight average molecular weight of 2 to 160,000 are used.

The mixing ratio (weight ratio) of the modified EPR and the chlorinated PO is the former / the latter = 1/9 to 8/2 (desirably 2).
/ 8 to 6/4). It is appropriately set within the above range depending on each substrate, the type of the top coating film, and the physical properties required for the coating film.

(4) To the modified EPR or a mixture of the modified EPR and chlorinated PO, a solvent is added together with the pigment, and the mixture is used as an undercoat paint of appropriate viscosity. As the solvent, aliphatic hydrocarbon type, ester type, alicyclic hydrocarbon type, ketone type, aromatic hydrocarbon type, alcohol ether type and the like can be used.

(3) The undercoat paint thus prepared is applied to a composite resin molded article, and then an overcoat film similar to the conventional one is applied and usually baked (for example, 80 ° C. × 40 minutes). At this time, the thickness of the undercoat paint is usually 5 to 15 μm.

[0038]

The function and effect of the present invention are as follows:
As described above, a coated composite resin molded article in which an upper coating film is formed via an undercoat coating film on a composite resin molded article obtained by integrally molding a PP-based material hard portion and a SEBS material soft portion, The main coating film element of the undercoat film is composed of modified EBR or a mixture of modified EPR and chlorinated PO, and the EPR has a weight average molecular weight of 90 to 140,000. It exerts its effects.

The polar group introduced into the modified EPR is responsible for the adhesion to the polar top coat film, and the good elongation of the EPR itself is responsible for the conformability to the soft part of the SEBS material. In addition, the EP is significantly higher than the general-purpose EPR
The molecular weight of R contributes to the increase in the adhesiveness with the base material as well as the resistance to chipping and the approximation of the molecular weight with the PP base material.

Further, the mixing of the chlorinated PO with the modified EPR contributes to the increase of the adhesion of the top coating film to the substrate.

Therefore, the coated composite resin molded article of the present invention is
As will be supported in Examples and Comparative Examples described later, a composite resin molded article in which a hard portion of a PP-based material and a soft portion of a SEBS material are integrally molded is sufficiently coated without TCE cleaning as a pretreatment. It has film adhesion and pitting resistance.

[0042]

EXAMPLES Examples and comparative examples conducted to confirm the effects of the present invention will be described below. In the following description, the mixing unit is a weight unit unless otherwise specified.

(1) The paints used are as follows. Examples Undercoat coating composition <Example 1> 58 parts (weight average molecular weight: 110,000, Tg: -42 ° C, carboxyl group introduction amount: 4.5 wt%) of carboxyl group-introduced modified EPR (solid content 11% toluene solution) Pigment (Titanium oxide type) 0.5 part Solvent 41.5 part (xylene / toluene / aromatic hydrocarbon / MIBK = 5/1/1/1) <Example 2> Carboxyl group-introduced modified EPR (same as Example 1) 5 parts Chlorinated PP toluene solution * 1) 15 parts (solid content: 20%, viscosity (25 ° C.): 60 cPs) Pigment (same as in Example 1) 2 parts Additive (leveling agent) 1 part Solvent 77 Parts (toluene / xylene / ester system = 5/2/3) * 1) Physical properties of polymer: weight average molecular weight: 55000, Tg: 35 ° C., softening point: 65 ° C., chlorination degree: 25%. Topcoat paint composition Polyester acrylic resin 27.7% Pigment (aluminum paste) 3.5% Solvent (hydrocarbon) 60.9% Additives (dispersant, stabilizer) 0.4% Hardener (HMDI puret type) ) 7.5% (2) Two-color molding of an over fender (composite resin molded product) using each of the following compositions, and then undercoating the over fender with the above paint under the conditions shown in FIG. And a top coat was applied. For reference, Table 1 shows various physical properties (injection molded products) of the PP-based material and the SEBS-based material.

Main body PP-based material composition: propylene-ethylene allomer 60 parts (ethylene content: 75%) EPR 30 parts Talc 10 parts Buffer part SEBS-based material composition : SEBS 30 parts PP homopolymer 25 parts Paraffin-based oil 45 parts (3 ) With respect to the overcoat film of each of the over fenders thus obtained, the tests of the following items were conducted.

Chipping resistance: Surface to be tested (4000 mm
² ) In response to basalt No. 6 from a projection gun, stone injection speed: 50 g / s, pressure: 0.4 MPa, distance: 30 cm,
Projection was performed under the conditions of a projection angle of 90 ° and an ambient temperature of −20 ° C., and the scratched area was used for judgment.

Flexibility: The coated surface of the test side (buffer section) was wrapped around a 4.8 mmφ mandrel at room temperature at a winding angle of 40 °, and the presence or absence of cracks on the coated surface was evaluated.

Coating peel strength: width: 1 cm, peel rate: 5
A 180 ° peel test was performed under the condition of 0 mm / min, and the strength at that time was measured.

Adhesion of coating film: After leaving at room temperature for 24 hours (initial) and after immersing in warm water at 40 ° C. for 240 hours (water resistance), a peeling test (JIS K 5400) at 2 mm intervals was conducted.

Adhesion after high-pressure car washing ... A molded product left for 24 hours was separated by 30 cm at a water pressure of 70 kg / cm ² .
The peeling length of the coating film after a 4-way high-pressure car wash every 10 seconds.

(4) From Table 2 showing the test results, each test piece using the undercoat paint of each Example was TCE cleaning-free,
It can be seen that the top coat has good adhesion to both the hard and soft parts of the substrate and good pitting resistance.

For reference, the elongation and tensile strength of the coating film alone were measured.
00%, 4.4 MPa (45 kgf / cm ² ), Example 2 is
It was 300% and 18.6 MPa (190 kgf / cm ² ).

[0052]

[Table 1]

[0053]

[Table 2]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mounting mode of an over fender, which is an example of a composite resin molded product to which the present invention is applied.

FIG. 2 is a drawing of a coating process in a test example.

[Explanation of Codes] 11 Overfender body 13 Overfender cushioning part 15 Body plate 17 Clip

Claims (5)

[Claims] 1. A coated composite resin molded article in which a hard coating portion of a PP-based material and a soft portion of an SEBS material are integrally molded, and a top coating film is formed on the composite resin molded article via an undercoat coating film. The main coating film element of the undercoat coating film is a polar group-introduced product of an amorphous ethylene propylene polymer (EPR) (hereinafter referred to as “modified E”).
BR ”. ), And the modified EPR has a weight average molecular weight of 90,000 to 140,000. 2. The coated composite resin molded article according to claim 1, wherein the modified EPR is a carboxyl group-introduced EPR. 3. A coated composite resin molded article in which a hard coating portion of a PP-based material and a soft portion of a SEBS material are integrally molded, and an upper coating film is formed on the composite resin molded article via an undercoat coating film. The main coating film elements of the undercoat are modified EBR and chlorinated P
A coated composite resin molded article comprising a mixture with O and a weight average molecular weight of the EPR of 90 to 140,000. 4. The coated composite resin molded article according to claim 3, wherein the modified EPR is a carboxyl group-introduced EPR and the chlorinated PO is chlorinated PP. 5. The coated composite resin molded article according to claim 1 or 3, wherein the top coating film is a urethane resin coating film.