JPH05255553A - Molded product of improved coatability and its production - Google Patents

Abstract

PURPOSE:To realize the abridgement of a coating process, the improvement of a working environment and the reduction of cost. CONSTITUTION:The title product is made from a polymer composition comprising 30-70wt.% polypropylene resin (A) of an ethylene content of 12wt.% or below and an MFR (under a load of 2.16kg at 230 deg.C) of 10-100g/10min., 30-70wt.% ethylene/propylene copolymer rubber (B) of a propylene content of 10-70wt.% and an ML1+4 (at 100 deg.C) of 5-300 and 0.1-25 pts.wt., per 100 pts.wt. total of components A and B, copolymer (C) of ethylene with a hydroxy unsaturated compound. The title process comprises dynamically heat-treating at least part of component B and at least part of component A in the presence of an organic peroxide and mixing the resulting mixture with the remainder of components A to C.

Description

Detailed Description of the Invention

[0001]

The present invention is excellent in flexibility and has an excellent quality balance, and the obtained molded article can be coated without surface modification such as primer coating and plasma treatment. The present invention relates to a molded product having paintability and improved paintability, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, automobiles have been rapidly changed to plastic parts for the purpose of improving fuel efficiency by reducing weight, and various plastics have been used for bumpers, fenders, wheel caps, doors, and bodies (partial parts), which were conventionally metal. Came to be used. Plastics used for such parts include SMC, RIM urethane,
Examples thereof include composite polypropylene, polycarbonate / ABS alloy material and the like. In particular, RIM urethane is widely used for bumpers and the like, but polypropylene-based composite resins containing ethylene / propylene rubber have come to be widely used in terms of cost and waste treatment. In addition, even in parts where other plastics such as spoilers, mudguards, and side moldings have been used in the past, polypropylene-based composite resins containing ethylene / propylene rubber are often used in terms of moldability, cost, and recycling. It's coming. However,
Polypropylene resin is a material that is chemically inactive because it does not have polar groups in the molecule and is extremely inferior in coatability. Therefore, one coat coating (only top coat) such as RIM urethane can be performed. Therefore, it is essential to perform surface modification in advance in the step of applying a primer or plasma treatment before the top coating step.

[0003]

In such a surface modification process, there have conventionally been the following problems. In the primer coating process, there is a drawback that the coating cost becomes high because an expensive primer must be used and the number of coating processes increases, and further, the solvent in the primer must be volatilized. Since it does not happen, there is a danger that a fire will easily occur, so there was a problem with safety. In addition, since the plasma treatment process is performed in a high vacuum state, an expensive device must be installed, and the batch system cannot avoid an increase in cost. Furthermore, the surface after the plasma treatment is unstable, and the adhesion of the coating material decreases when it comes into contact with foreign matter, so that the coating film performance tends to vary, and handling is very inconvenient. Therefore, if such a primer coating process and plasma treatment process can be omitted, the coating process can be simplified and the working environment can be improved.
Since it is possible to reduce costs,
Much research has been done so far to achieve the omission of these steps. However, in the end, this purpose has not yet been achieved, and it is not possible to omit such primer coating and plasma treatment steps, and the actual situation is that the coating is performed after performing these surface modification treatments. is there.

[0004]

Means for Solving the Problems [Summary of the Invention] The inventors of the present invention have earnestly conducted various studies in order to achieve the above-mentioned objects, and as a result, a propylene-based resin composition of a specific material, composition and compounding order It is possible to obtain a molded article with improved coating, which has excellent paint adhesion performance and flexibility, even though the coating material is directly applied by omitting the steps of primer coating and plasma treatment. The present invention was completed based on the knowledge that

That is, the molded article of the present invention having improved coatability is composed of a polymer composition comprising the following components A to C, and the gel fraction of the polymer composition is 2 to 40.
%, And the flexural modulus shows a value of 500 to 10,000 kg / cm ² . Component A: Polyethylene resin having an ethylene content of 12% by weight or less and a load of 2.16 kg at 230 ° C. of 10 to 100 g / 10 minutes 30 to 70% by weight Component B: 10 to 70% by weight of propylene, ML _{1 + 4} ( 100 ° C.) 5 to 300 ethylene / propylene copolymer rubber 30 to 70% by weight, based on 100 parts by weight of the total of these component A and component B, component C: copolymerization of ethylene and a hydroxyl group-containing unsaturated compound Combined 0.1 to 25 parts by weight

The method for producing a molded article having improved paintability, which is another aspect of the present invention, is a method in which the following components A to C are dynamically heat treated in the presence of an organic peroxide and then injected. molded to from 2 to 40 percent gel fraction, flexural modulus in a method for producing a coating for an improved molded body showing a value of 500~10,000kg / cm ^2, of the component A~ component C In the mixing, first, at least a part of the component B and at least a part of the component A are dynamically heat-treated in the presence of an organic peroxide, and then the remaining components are mixed.
It is characterized by. Component A: Polyethylene resin having an ethylene content of 12% by weight or less and a load of 2.16 kg at 230 ° C. of 10 to 100 g / 10 minutes 30 to 70% by weight Component B: 10 to 70% by weight of propylene, ML _{1 + 4} ( 100 ° C.) 5 to 300 ethylene / propylene copolymer rubber 30 to 70% by weight, based on 100 parts by weight of the total of these component A and component B, component C: copolymerization of ethylene and a hydroxyl group-containing unsaturated compound Combined 0.1 to 25 parts by weight

[Detailed Description of the Invention] [I] Production of Polymer Composition (1) Raw Material (a) Constituent Component (Essential Component) Component A: Polypropylene Resin Constituting a Molded Product with Improved Paintability of the Present Invention The polypropylene resin used in the polymer composition has an ethylene content of 12% by weight or less, preferably 10% by weight or less, and an MFR of 230 ° C. and a load of 2.16 kg.
Is 10 to 100 g / 10 minutes, preferably 10 to 80 g /
It is important to use 10 minutes polypropylene resin. When the ethylene content of the polypropylene resin exceeds the above range, the heat resistance becomes poor when used as a molded product having improved coatability. Here, the ethylene content in the polypropylene resin is a value measured by an infrared absorption spectrum analysis method or the like, and the MFR is JIS-K.
It is a value measured according to 7210. This polypropylene resin is within a range that does not significantly impair the effects of the present invention. Other unsaturated monomers, for example, other α-olefins such as butene-1 and hexene-1, 7-methyl-1,6.
-Octadiene, 5-methyl-1,4-hexadiene,
Non-conjugated dienes such as 4-methyl-1,4-hexadiene and 1,9-decadiene, vinyl esters such as vinyl acetate, unsaturated silane compounds such as vinyltrimethoxysilane, (meth) acrylic acid (ester) and maleic anhydride. It may be a ternary or higher copolymer (which may be a graft type, a random type, or a block type) containing an unsaturated organic acid such as an acid or a derivative thereof.

Component B: ethylene / propylene copolymer
Rubber The ethylene / propylene-based copolymer rubber used in the polymer composition constituting the molded article with improved coatability of the present invention has a propylene content of 10 to 70% by weight, preferably 20 to 50% by weight, And ML _{1 + 4} (1
00 ° C) (Moonie viscosity) is 5 to 300, preferably 1
It is important to use an ethylene / propylene copolymer rubber of 0 to 100. If the propylene content of the ethylene / propylene-based copolymer rubber is less than the above range, the flexibility is inferior when it is used as a molded article with improved coatability, while it exceeds the above range. Has a poor paintability. The content of the propylene component in this ethylene / propylene copolymer rubber is a value measured by a conventional method such as an infrared absorption spectrum analysis method or an NMR method. If the ML _{1 + 4} (100 ° C.) (Moonie viscosity) of the ethylene / propylene copolymer rubber is less than the above range, the coatability becomes poor, and if it exceeds the above range, the processability becomes poor. This ethylene / propylene-based copolymer rubber may be any other unsaturated monomer such as butene-1 as long as it does not significantly impair the effects of the present invention.
Other α-olefins, 5-ethylidene norbornene, and dicyclopentadiene may be used as a ternary or higher copolymer containing a third component. Specifically, ethylene / propylene binary copolymer rubber (EPM) and ethylene / propylene / non-conjugated diene terpolymer rubber (EPDM),
Examples thereof include ethylene / propylene / butene-1 terpolymer rubber. The production method and shape of these ethylene / propylene copolymer rubbers are not particularly limited.

Component C: ethylene and a hydroxyl group-containing unsaturated compound
As a copolymer of ethylene and a hydroxyl group-containing unsaturated compound used in the polymer composition constituting the molded article of the present invention having improved paintability, ethylene and 2-hydroxyethyl methacrylate are, for example, It is a polymer copolymerized randomly or at certain intervals, but here, from a structural point of view, a hydroxyl group-containing compound is copolymerized randomly or regularly in a branched or carbon chain. Refers to all things that have the structure. Specifically, the content of the hydroxyl group-containing unsaturated compound is 0.1 to 50% by weight,
Preferably 0.5 to 45% by weight, particularly preferably 1 to 4
0% by weight, having a molecular weight of 200 to 200,000, preferably 500 to 10 from the viewpoint of the effect of the coating property of the present invention.
Included are polymers that are liquid, semi-solid, or solid at ambient temperature of 10,000, particularly preferably 800-10,000. When the molecular weight is out of the above range, the coating property is significantly reduced. The copolymer of ethylene and a hydroxyl group-containing unsaturated compound can be produced using ethylene and a hydroxyl group-containing unsaturated compound as a raw material by a well-known method such as a high pressure radical polymerization method. When the copolymer is produced by a high-pressure radical polymerization method, ethylene, a hydroxyl group-containing unsaturated compound and a radical reaction initiator are added, for example, at a pressure of 1,000 to
In a reaction zone kept at 3,000 kg / cm ³ and a temperature of 90 to 280 ° C., the ethylene: hydroxyl group-containing unsaturated compound ratio was continuously adjusted to be 1: 0.0001 to 1: 0.02. It is produced by feeding and converting 3 to 20% of the raw material ethylene to the above copolymer, and continuously taking out the copolymer from the reaction zone.

Examples of the hydroxyl group-containing unsaturated compound used herein include 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, poly (ethylene glycol) monomethacrylate and the like.

In addition to ethylene and a hydroxyl group-containing unsaturated compound component, as a third copolymer component, unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate and methyl methacrylate; styrene and α-methylstyrene. , Vinyl compounds such as vinyltoluene; nitrile compounds such as acrylonitrile,
Vinyl pyridine such as 2-vinyl pyridine and 4-vinyl pyridine; vinyl ether such as methyl vinyl ether and 2-chloroethyl vinyl ether; vinyl halide such as vinyl chloride and vinyl bromide; vinyl ester such as vinyl acetate; acrylamide It can also be used as a ternary or multi-component copolymer. And these copolymers can be used individually or as a mixture of two or more.

(B) Additional component (component D) The polymer composition constituting the molded article with improved coatability of the present invention is basically a mixture of the above-mentioned components (essential components). However, in general, in order to add a pigment for coloring or to improve other various performances, as an additional component (component D) in addition to components A to C which are the above essential components. Hydrocarbon rubber softener (average molecular weight 300 to 1,000), various plasticizers, antioxidants,
Various additives such as antistatic agents, flame retardants and dispersants can also be added. Further, compounding materials such as various resins other than the respective components A to C, various elastomers, various fillers such as glass fibers, glass balloons, carbon fibers and the like can be blended within a range that does not significantly impair the effects of the present invention. .. The hydrocarbon-based softening agent for rubber, which is added as an additional component, plays an important role in controlling the processability and flexibility. Such a hydrocarbon-based softening agent for rubber is composed of a mixture of an aromatic ring, a naphthene ring, and a paraffin chain, and has 50% or more of the total number of hydrocarbons in the paraffin chain. Those having a naphthene ring carbon number of 30 to 45% are called naphthene type, and those having an aromatic carbon number of more than 30% are called aromatic type. Among these softeners for hydrocarbon-based rubber, preferred are softeners for paraffin-based rubber.

(C) Amount ratio The polymer composition constituting the molded article of the present invention having improved coatability is basically the component A of the above-mentioned constituent components (essential components).
~ Each component C is blended, and the blending ratio of each component is particularly important. The amount of the component A is 30 to 70 in 100 parts by weight of the total amount of the component B.
It is used in parts by weight, preferably 55 to 65 parts by weight. Therefore, the blending amount of the component B is 70 to 30 parts by weight, preferably 45 to 30 parts by weight based on 100 parts by weight of the total amount of the component A.
Used in a proportion of 35 parts by weight. If the blending amount of the component A exceeds the above range, that is, if the blending amount of the component B is less than the above range, the coating strength and the impact strength are poor, and the blending amount of the component A is less than the above range, that is, the blending amount of the component B. If it exceeds the above range, the heat resistance and surface hardness will be inferior, which is unsuitable. It is preferable for the amount to be blended within the preferred range since it will be good in terms of coating performance and mechanical strength. The blending amount of the component C is 0.1 to 25 parts by weight, preferably 0.1 part by weight, based on 100 parts by weight of the total amount of the components A and B.
It is 1 to 18 parts by weight, and particularly preferably 0.5 to 12 parts by weight.

(2) Heat treatment) (Production method) In order to obtain a polymer composition which constitutes the molded article of the present invention with improved coatability, components A to C, which are essential constituent components of the polymer composition, are added. , Optionally additional component D
Is blended and is dynamically heat-treated in the presence of organic peroxide. In this case, first, the component A
The coating property becomes better by dynamically heat treating at least a part of the component B and at least a part of the component B in the presence of the organic peroxide and then mixing the remaining components. (a) Treatment conditions The heat treatment is generally 160 to 280 ° C, preferably 180.
It is carried out at a temperature of ~ 250 ° C. (b) Processing device The dynamic heat treatment, for example, a single-screw extruder, a twin-screw extruder,
It is generally carried out by kneading using a usual kneading machine such as a Banbury mixer, roll, Brabender plastograph and kneader. For the treatment with these kneading machines, it is preferable to select a kneading method that allows good dispersion of each component, and it is preferable to carry out such kneading using a twin-screw extruder. (c) Treatment method A first step of dynamically heat treating in the presence of an organic peroxide to produce a partially crosslinked product, and a second step of further mixing the obtained partially crosslinked product with the remaining components. It consists of

First Step In the first step, at least part of the component A and at least part of the component B are dynamically heat-treated in the presence of an organic peroxide to partially crosslink. In this case, it is also possible for a suitable amount of the additional components to be present at the same time. In the partial cross-linking in the first step, a cross-linking aid can be used together with the organic peroxide as the cross-linking agent.
Alternatively, the components A to C and the additional components may be dynamically heat-treated simultaneously in the final blending ratio in the presence of an organic peroxide. Therefore, in this case, the second step is not necessary.

Organic Peroxide As the organic peroxide, either an aromatic type or an aliphatic type can be used, and a single peroxide or a mixture of two or more kinds of peroxides may be used. Specifically, 2,5-dimethyl-2,5-di (benzoylperoxy) -hexane, t-butylperoxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-di (t- Butyl peroxy) -hexane, t-butyl cumyl peroxide, diisopropyl benzohydroperoxide, 1,3-bis- (t-
Butyl peroxyisopropyl) -benzene, benzoyl peroxide and the like can be mentioned. The amount of such organic peroxide used is usually 0.05 to 1.0 part by weight, preferably 0.1 part by weight, relative to 100 parts by weight of the component B.
Although it is about 1 to 0.5 parts by weight, it actually affects the type of Component B, the compounding ratio, and the quality of the resulting resin composition. Therefore, consider the degree of crosslinking of Component B (gel fraction) and the like. The amount is determined. The degree of crosslinking of component B (gel fraction) in the partially crosslinked product obtained in the first step can be measured by the same method as in "Measurement of gel fraction" described later.
The degree of crosslinking of the polymer resin constituting the molded article of the present invention with improved coatability is 2 to 40% by weight, preferably 5 to 30% by weight in the above-mentioned measured value in this first step. When the content is less than 2% by weight, the heat distortion resistance of the polymer composition finally obtained is not improved.

Cross-Linking Auxiliary As a cross-linking auxiliary which is optionally used in combination with the above-mentioned peroxide, other than acrylic polyfunctional monomers such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane triacrylate and the like. , Divinylbenzene, liquid polybutadiene, and the like. The amount of the organic peroxide used in the first step and the crosslinking aid used as necessary is usually 0.1 to 10 parts by weight, preferably 0.2 to 3 parts by weight, relative to 100 parts by weight of the component B. Although it is a degree, it actually affects the type of component B, the compounding ratio, and the quality of the polymer composition to be obtained, so the amount thereof is determined in consideration of the degree of crosslinking of component B and the like. The cross-linking in the first step is carried out by dynamically heat-treating each component used in this step in the presence of peroxide, and in this case, "dynamically" means, for example, each blended Heat treatment in the presence of peroxide while sufficiently kneading the components. Therefore, such a heat treatment is generally carried out by a kneading method using an apparatus equipped with a stirrer such as a Banbury mixer or an extruder (for example, Japanese Patent Publication No. 53).
No. 34210, Japanese Patent Publication No. 54-2662, etc.) or a method of introducing a peroxide or the like into a pelletized composition comprising each component and then heat treating it in warm water (for example, JP-A No. 56-98248)
Etc. can also be adopted.

Second Step In the second step, the cross-linked product obtained in the first step and the remaining components A, B and C, and optionally the remaining amount of the additional component (component D) are blended. .. The following three methods are adopted as the compounding method in the second step. A method of kneading the cross-linked product obtained in the first step and the remaining components. A method of blending by dry-blending a composition obtained by previously kneading the remaining components not used in the first step in a separate step and the crosslinked product of the first step. A method of further kneading the above dry-blended composition.

[II] Production of Molded Article (1) Molding The polymer composition obtained as described above can be molded into various molded articles by various known molding methods. Specific examples include injection molding, compression molding, extrusion molding (sheet molding, blow molding) and other molding methods. However, among these various molding methods, it is preferable to use an injection molding method in which a molding machine is injection-molded by using an extruder.

(2) Molded Body The injection molding can be carried out by the same method as a usual injection molding method. The thus obtained molded article with improved coatability of the present invention is composed of a polymer composition comprising the following components A to C, and the gel fraction of the polymer composition is 2 to 40%, Flexural modulus of 500 to 10,0
It shows a value of 00 kg / cm ² . Component A: Polyethylene resin having an ethylene content of 12% by weight or less and a load of 2.16 kg at 230 ° C. of 10 to 100 g / 10 minutes 30 to 70% by weight Component B: 10 to 70% by weight of propylene, ML _{1 + 4} ( 100 ° C.) 5 to 300 ethylene / propylene copolymer rubber 30 to 70% by weight, based on 100 parts by weight of the total of these component A and component B, component C: copolymerization of ethylene and a hydroxyl group-containing unsaturated compound Combined 0.1 to 25 parts by weight Further, the obtained molded product has a good appearance of a molded product, flexibility and a flexural modulus of 500 to 10,000 Kg / cm ² , and low temperature impact resistance. It shows a value and is a molded product with an excellent quality balance.

(3) Physical Properties (a) Gel Fraction The degree of crosslinking in the molded article of the present invention with improved coatability is
2 to 40% by weight, preferably 5 to 30 by the following measuring method
When the degree of crosslinking is less than 2% by weight, the heat-deformation resistance of the molded product becomes poor. Measurement method The cross-linking degree (gel fraction) of component B in the partially cross-linked product obtained in the first step was measured by adding 1 g of the partially cross-linked product obtained in the first step to a Soxhlet extractor with boiling xylene. After 10 hours of extraction, the residue was passed through a wire mesh of 80 mesh and the solid content obtained was 1 g of the same sample.
The value is obtained by multiplying the value divided by the blending amount of the component B in the product by 100 (% by weight). (b) Flexural modulus The flexural modulus of the molded article of the present invention having improved paintability is 500 to 10,000 kg / cm according to the following measurement method.
² , preferably 1,000 to 10,000 kg / cm ^2.
The bending elastic modulus is less than the above range, resulting in poor processability of the finally obtained polymer composition,
If the flexural modulus exceeds the above range, the flexibility becomes poor. Measuring method The flexural modulus is measured according to JIS-K-7203.

[III] Coating (1) Coating Method A coating material is directly applied to the surface of the molded article obtained as described above to form a coating film directly on the surface. As a coating method, the conventional coating process can be performed by removing the primer coating process. Further, the plasma treatment process performed to enhance the adhesion of the coating film can be omitted. That is, the paint can be directly applied to the molded body that has not been subjected to the surface modification step. However, auxiliary surface treatment such as degreasing treatment may be performed before applying the paint. Such degreasing treatment is a normal operation that is generally performed immediately before applying a coating, and as a result of this, the debris and machinery that inevitably adhere to the surface of the molded product in the steps from molding of the molded product to pre-painting. It is possible to wash and remove oil and the like. Specifically, there is a cleaning method using an organic solvent liquid or its vapor, water, steam, acid, alkali liquid or a surfactant aqueous solution. Among these, there are washing methods using organic solvent vapor, water and hot water. Alternatively, washing with water or warm water added with an alkaline solution or a neutral detergent, alcohol washing, or the like is preferably used. As a coating means for coating, there are spraying, brush coating, roller coating, and the like, and any method can be adopted.

(2) Coating materials As coating materials, generally widely used coating materials such as acrylic-based coating materials, epoxy-based coating materials, polyester-based coating materials,
Urethane-based paints, alkyd-based paints, melamine-based paints, etc. can be mentioned. Among these, acrylic paints, melamine paints, polyester paints and urethane paints are preferably used.

(3) Painted Molded Product The molded product of the present invention having improved coatability is coated with a coating material in a thickness of generally 10 to 100 μm, preferably 15 to 70 μm in the case of a soft automobile member. The coating film is usually 500 g / cm or more, especially 700 to 2,000 g / c.
It adheres firmly with a peel strength of m and is excellent in hot water resistance, which is extremely important in coating performance, and also has a high level of weather resistance in unpainted parts that are directly exposed to sunlight. For fenders, door panels, bumpers, spoilers,
It is highly practical as an automobile member such as a mudguard, a side molding, a wheel cap, an instrument panel, a trim, a console and a handle pad.

[0025]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples below. The raw materials, coating method and evaluation method used here are as follows. [I] Raw material (1) Component A a-1: Contains 14% by weight of room temperature xylene-soluble component having an ethylene content of 40% by weight, the total ethylene content of the copolymer was 9% by weight, and the MFR was 40 g / 10 min. A-2: 16% by weight of room temperature xylene-soluble component having an ethylene content of 30% by weight, ethylene content of the entire copolymer is 7.5% by weight and MFR is 10 g. Propylene / ethylene block copolymer having a content of / 10 minutes, a-3: containing 16% by weight of a room temperature xylene-soluble component having an ethylene content of 30% by weight, the total copolymerization has an ethylene content of 12% by weight and an MFR of 80 g. Propylene / ethylene block copolymer of / 10 minutes, a-4: flexural modulus of 13,000 kg / cm ² , and M
FR 25g / 10min polypropylene,

(2) Component B b-1: Mooney viscosity ML _{1 + 4} (100 ° C.) 24, ethylene / propylene copolymer rubber (EPM) having a propylene content of 26% by weight, b-2: Mooney viscosity ML _{1 + 4} (100 ° C.) 70, ethylene / propylene copolymer rubber (EPM) with propylene content 27% by weight, b-3: Mooney viscosity ML _{1 + 4} (100 ° C.) 90, ethylene / propylene copolymer rubber with propylene content 28% by weight (EPM), b-4: Mooney viscosity ML _{1 + 4} (100 ° C.) 70, ethylene / propylene copolymer rubber (EPM) having a propylene content of 70% by weight,

(3) Component C c-1: 2-hydroxyethyl methacrylate content obtained by high pressure radical polymerization method: 10% by weight, molecular weight: 5
4,000 ethylene-2-hydroxyethylmethacrylate copolymer c-2: 2-hydroxyethylmethacrylate content 10 wt%, methyl acrylate content 10 wt%, molecular weight 32,000, obtained by high pressure radical polymerization method. Ethylene-2-hydroxyethyl methacrylate / methyl acrylate copolymer c-3: 2-hydroxyethyl methacrylate content 10% by weight, molecular weight 9, obtained by high pressure radical polymerization method
Ethylene-2-hydroxyethylmethacrylate copolymer c-4: 2-hydroxyethylmethacrylate content 35% by weight, molecular weight 2, obtained by high pressure radical polymerization method
Ethylene-2-hydroxyethyl methacrylate copolymer of 300

(4) Component D d-1: paraffin oil having an average molecular weight of 746 and a ring analysis of 0%,

(5) Component E: Organic peroxide e-1: Kayaku Nouri Co. "Perkadox 14/4"
0 ”[40% diluted product of 1,3-bis- (t-butyl-peroxy-isopropyl) benzene, diluent: calcium carbonate], all the peroxide compounding parts in Examples and Comparative Examples are converted to pure products. It is the numerical value.

[II] Coating Method (1) Pretreatment and Baking Treatment The molded flat plate was subjected to the following pretreatments, respectively, and then the coating material was coated using an air gun. After baking and drying, 4
It was left at room temperature for 8 hours and a paintability test was conducted. 20 seconds degreasing treatment with trichloroethane vapor (TC
E treatment) (2) Coating A commercially available polyester urethane-based paint was used for coating. (3) Coating cloth Mix each paint and use an air spray gun to
Spray coating was performed so that the coating film thickness was about 30 μm and about 100 μm.

[III] Evaluation method (1) Measurement of gel fraction The gel fraction (degree of crosslinking) was measured by boiling 1 g of the partially cross-linked sample obtained in the first step with a Soxhlet extractor. After extraction with xylene for 10 hours, the residual content was adjusted to 80
The weight of the solid content obtained through the wire mesh of the mesh was divided by the compounding amount of the component B in 1 g of the same sample, and the value was multiplied by 100 (% by weight). (2) Measurement of flexural modulus The molded specimen was measured according to JIS-K7203. The measurement temperature is 23 ° C. (3) Evaluation of paint adhesion (a) Cross-cut stripping Make a cross-cut with a single-edged razor by drawing 11 parallel and 11 horizontal and vertical lines parallel to the surface of a test piece coated to a thickness of about 30 μm at 1 mm intervals. .. Cellophane adhesive tape (JIS-Z1522) was sufficiently pressure-bonded on it, and the surface of the coating was about 3
While keeping it at 0 degree, it was peeled off at once in front, the state of the part surrounded by the grid was observed, and the number of grids that did not peel was recorded. (b) Peel strength The surface of a test piece coated with a thickness of about 100 μm is linearly cut with a single-edged razor to a width of 1 cm, and the strip of the coating film is turned over 180 ° at a speed of 50 mm / min with a tensile tester. It was pulled in a shape and the load at the time of peeling was read. (c) Warm water resistance test After being immersed in 40 ° C. hot water for 240 hours, it was evaluated by a goose eye test.

[IV] Experimental Example Example 1 (1) First Step Ingredients A, B, and D were blended in the proportions shown in Table 1, and this was blended in a Banbury mixer (60 rpm) having a volume of 4 liters. Then, component E is added at a ratio of 0.3 parts by weight to 100 parts by weight of the total amount of components A and B, and kneaded at a temperature of 240 ° C. for about 5 minutes to form a partially crosslinked product. Obtained. Then, this was sheeted by a roll and subjected to a sheet cutter to form pellets. (2) Second step Based on 100 parts by weight of the total amount of the partially crosslinked product component obtained in the first step, the component C in the ratio shown in Table 1, the remaining components A and B, and the total amount of the component A and the component B. , Pentaerythrityl-
0.1 parts by weight of tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], bis (2,2,6,6-tetramethyl-4-piperidyl)
0.2 parts by weight of sebacate and 0.8 of carbon black
1 part by weight at room temperature with Henschel mixer
After mixing for 2 minutes, a twin-screw extruder (PCM4 manufactured by Ikegai Tekko KK
5, 200 ° C., 210 rpm) was kneaded to obtain a resin composition. This resin composition was injection-molded, and its physical properties were measured and evaluated according to the coating method and the evaluation method. The results are shown in Tables 1 to 4.

Examples 2 to 15 and Comparative Examples 1 to 4 The procedure of Example 1 was repeated, except that the proportions shown in Tables 1 to 4 were used. The results are shown in Tables 1 to 4.

Example 16 Components A to D were blended in the proportions shown in Table 1 and kneaded with the above extruder to obtain a resin composition. In this case, the component E is 0.3 with respect to 100 parts by weight of the total amount of the components A and B.
It was compounded in a ratio of parts by weight. The ingredients were blended in the proportions shown in Table 1, and molding and evaluation were carried out in the same manner as in Example 1. The results are shown in Table 3.
Shown in.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

The molded article of the present invention having improved paintability is
Unlike conventional automobile parts molded with propylene-based soft resin, the paint can be applied directly to the surface of the molded product without applying a modification treatment such as primer coating or plasma treatment. It is possible to improve the environment, reduce costs, etc. Moreover, since the product obtained is excellent in flexibility, bumper, spoiler,
It can be widely used as various automobile parts such as mat guards, side moldings, wheel caps and instrument panels.

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Claims (2)

[Claims] 1. A polymer composition comprising the following components A to C, wherein the gel fraction of the polymer composition is 2 to
40%, flexural modulus 500-10,000 kg / cm
A molded article with improved paintability, characterized by exhibiting a value of ² . Component A: Polyethylene resin having an ethylene content of 12% by weight or less and a load of 2.16 kg at 230 ° C. of 10 to 100 g / 10 minutes 30 to 70% by weight Component B: 10 to 70% by weight of propylene, ML _{1 + 4} ( 100 ° C.) 5 to 300 ethylene / propylene copolymer rubber 30 to 70% by weight, based on 100 parts by weight of the total of these component A and component B, component C: copolymerization of ethylene and a hydroxyl group-containing unsaturated compound Combined 0.1 to 25 parts by weight 2. The following components A to C are dynamically heat treated in the presence of organic peroxide and then injection molded to have a gel fraction of 2 to 40% and a flexural modulus of 500 to 10,000.
In the method for producing a molded article having an improved coating property showing a value of kg / cm ^2, the components A to D are mixed by first mixing at least a part of the component B and at least a part of the component A with an organic solvent. After dynamically heat treating in the presence of oxide,
A method for producing a molded article having improved paintability, which comprises mixing the remaining components. Component A: Polyethylene resin having an ethylene content of 12% by weight or less and a load of 2.16 kg at 230 ° C. of 10 to 100 g / 10 minutes 30 to 70% by weight Component B: 10 to 70% by weight of propylene, ML _{1 + 4} ( 100 ° C.) 5 to 300 ethylene / propylene copolymer rubber 30 to 70% by weight, based on 100 parts by weight of the total of these component A and component B, component C: copolymerization of ethylene and a hydroxyl group-containing unsaturated compound Combined 0.1 to 25 parts by weight