JP2001310978A - Thermoplastic resin composition, moldings using the same and painted article thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for affording paintability to a non-polar polyolefin resin. SOLUTION: This thermoplastic resin composition comprises (A) a non-polar polyα-olefin resin and (B) an epoxized diene-type block copolymer in which the ratio of melt flow rate of component (A) to component (B) (measured under conditions of 230 deg.C and 2.16 kg load) is 13 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition excellent in coatability suitable as an automobile part, a home appliance part, an industrial part or daily goods, a molded article thereof, and a coated body thereof.

[0002]

2. Description of the Related Art Polyolefin resins are widely used as various molded articles because of their excellent physical properties and moldability. However, nonpolar polyolefin-based resins have problems in paintability and adhesion of coating films, and improvements are required.

[0003] For example, a polypropylene resin, which is one of polyolefin resins, is lightweight, excellent in rigidity, hardness, heat resistance and the like, and can be easily obtained by various molding methods such as injection molding, calender molding and extrusion molding. Because it can be made into a shape and it is inexpensive, it is conventionally used for automotive interior applications such as instrument panels, trims, pillars, etc., automotive exterior applications such as fenders, bumpers, side moldings, mudguards, mirror covers, automobile parts,
It is widely used for home appliances, industrial parts and household goods.

[0004] However, since the polypropylene resin is non-polar, there is a problem that, when the molded article is coated, the adhesiveness with the paint is poor and the coating film is peeled off from the surface of the polypropylene resin molded article. Thus, non-polar polyolefin resins such as polypropylene resins are generally coated after surface treatment.

[0005] The surface treatment performed before coating is performed for the purpose of degreasing or imparting polarity to the surface of a non-polar polyolefin resin molded article, and specifically, using a halogenated hydrocarbon solvent such as trichloroethane. After the surface treatment, the surface is oxidized by corona discharge, plasma jet, or the like, or a polar group is generated to perform coating.

In addition to surface treatment, as a method of imparting coating properties to a nonpolar polyolefin resin composition, a method of adding an ultra-low molecular weight ethylene propylene rubber (EPR) is generally used. In addition, a method of adding a polyolefin modified with a compound having a polar group (JP-A-6-157838) and a method of adding a polyolefin modified with a compound having an unsaturated hydroxyl group (JP-A-5-39383) JP-A-3-1571), a method of adding an oligomer having a polar group at the terminal
68) has been proposed.

Further, as a method for improving the coating property of the polypropylene resin, a method of blending a vinyl polymer, for example, polystyrene, with the polypropylene resin has been used. JP-A-58-93730 discloses an attempt to disperse polystyrene in a polypropylene resin by blending a polystyrene-modified propylene resin produced by a specific method with a propylene resin.

[0008] However, surface treatment with a halogenated hydrocarbon solvent is not preferable from the viewpoint of environmental problems, and the method of adding a modified polyolefin requires an operation of modifying the polyolefin and is not efficient. Furthermore, regarding the compatibility of the polymer to be added and the propylene-based polymer, the behavior greatly differs due to the difference in viscosity between the two polymers, and the compatibility becomes poor when the melt flow rate ratio (viscosity difference) increases. In addition, an increase in the particle size of the dispersed phase in the molded article causes poor dispersion, resulting in localization inside the molded article and less orientation near the surface. Also, polypropylene resin and polystyrene are generally incompatible with each other, so that only a small amount can be blended.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for imparting paintability to a non-polar polyolefin resin.

[0010]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the epoxidation of a non-polar α-olefin resin having a melt flow rate ratio of a certain value or less has been considered. It has been found that the addition of a diene-based copolymer improves the adhesion of the paint, and the present invention has been completed.

That is, the first aspect of the present invention is that (A) non-polar α
An olefin-based resin and (B) an epoxidized diene-based block copolymer, and a melt flow rate of the component (A) and the component (B) (measurement conditions: 230 ° C., 2.16 k;
It is a thermoplastic resin composition having a ratio (component (A) / component (B)) of 13 or less (under g load). In the second aspect of the present invention,
(A) 50 to 97% by mass of a non-polar α-olefin resin
The thermoplastic resin according to the first aspect of the present invention, wherein the epoxidized diene-based copolymer (B) is 3 to 50% by mass (the total of (A) and (B) is 100% by mass). It is a resin composition. A third aspect of the present invention is that the epoxidized diene-based block copolymer (B) converts oxirane oxygen to 0.8 to 6
% Of the present invention.
3. The thermoplastic resin composition according to any one of claims 1 to 2. A fourth aspect of the present invention is a molded product obtained by molding the thermoplastic resin composition according to any one of the first to third aspects of the present invention into a predetermined shape. A fifth aspect of the present invention is a coated article of a molded article obtained by coating a molded article obtained by molding the thermoplastic resin composition according to the fourth aspect of the present invention into a predetermined shape.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the thermoplastic resin composition of the present invention, its molded product and its coated body will be described in detail. In this specification, the International System of Units is used as a unit with the enforcement of the New Measurement Law. Therefore, "weight" conventionally used in the meaning of mass is described as "mass". Accordingly, “% by weight”, “parts by weight”, etc.
Described as "parts by mass" or the like.

[(A) Non-polar α-olefin resin] The amount of the (A) non-polar α-olefin resin used in the present invention is based on the resin composition (component (A) and component (B)). The total is 100% by mass.)
It is preferred that If the amount is less than the above range, the rigidity and heat resistance of the molded article decrease, and if it exceeds the above range, the impact resistance of the molded article decreases.

The non-polar α-olefin resin (A) used in the present invention is a melt flow rate (hereinafter abbreviated as MFR, which satisfies the viscosity ratio described in claim 1; measurement conditions; ASTM).
As long as the resin is a nonpolar α-olefin resin having a D1238 value at 230 ° C. under a load of 2.16 kg, a known resin is used without any particular limitation.

The non-polar α-olefin resin may be a homopolymer of a non-polar α-olefin monomer or a copolymer of two or more monomers. Specifically, ultra low density, low density, medium density, high density polyethylene, propylene homopolymer, polybutene-1, poly-
Examples thereof include a homopolymer such as 4-methylpentene, an ethylene-based copolymer, and a propylene block copolymer.
In addition, these manufacturing methods are not particularly limited.

Of these, propylene homopolymers and / or propylene block copolymers are preferred.

When the non-polar α-olefin resin is a propylene / ethylene block copolymer, the unit derived from ethylene is 0.5 to 8 mol%, preferably 1 to 8 mol%.
It is desirable for the content to be about 7 mol%. The amount of the unit derived from ethylene is abbreviated as the ethylene content.

The ethylene content can be determined by ¹³ C-NMR analysis. The crystallinity of such a propylene / ethylene block copolymer measured by an X-ray diffraction method is usually 56% or more, preferably 60% or more, and more preferably 65 to 95%. The crystallinity may be based on isotactic or syndiotactic.

In the present invention, two or more nonpolar α-olefin resins (A) as described above can be used.

[(B) Epoxidized diene-based block copolymer] The (B) epoxidized diene-based block copolymer used in the present invention is obtained by epoxidizing a diene-based block copolymer or a partially hydrogenated product thereof. Things.

The diene block copolymer referred to herein is a block copolymer comprising a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound. Mass ratio of group compound and conjugated diene compound (mass ratio of block copolymer)
Is preferably 25/75 to 95/5, more preferably 25/75 to 80/20. The number average molecular weight of the block copolymer used in the present invention is from 5,000 to
1,000,000, preferably 10,000-800,
000 and the molecular weight distribution [mass average molecular weight (M
w) and the number average molecular weight (Mn) (Mw / Mn)] is 10
It is as follows. The molecular structure of the block copolymer may be linear, branched, radial, or any combination thereof. For example, XYX, YXY
It is a vinyl aromatic compound (X) block-conjugated diene compound (Y) block copolymer having a structure such as -X, (XY-) 4Si, and XYXYX. Further, the unsaturated bond of the conjugated diene compound of the diene-based block copolymer may be partially hydrogenated.

Examples of the vinyl aromatic compound constituting the diene block copolymer include styrene, α-methylstyrene, vinyltoluene, p-tertiary butylstyrene, divinylbenzene, p-methylstyrene, 1,1-
One or more of diphenylstyrene and the like can be selected, and among them, styrene is preferable. As the conjugated diene compound, for example, butadiene, isoprene,
One of 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, phenyl-1,3-butadiene and the like.
Species or two or more species are selected, and among them, butadiene, isoprene and a combination thereof are preferred.

As a method for producing the block copolymer used in the present invention, any production method having the above-mentioned structure can be adopted. For example,
23798, JP-B-47-3252, JP-B-48-
No. 2423, JP-A-51-33184, JP-B-46-
No. 32415, JP-A-59-166518, Japanese Patent Publication No. Sho 4
Nos. 9-36957, JP-B-43-17979, JP-B-46-32415, JP-B-56-28925, and the like. A compound-conjugated diene compound block copolymer can be synthesized. Further, hydrogenation in an inert solvent in the presence of a hydrogenation catalyst by a method described in JP-B-42-8704, JP-B-43-6636, or JP-A-59-133203, The partially hydrogenated block copolymer used in the present invention can be synthesized.

The epoxidized diene-based block copolymer in the present invention can be obtained by reacting the above-mentioned block copolymer with an epoxidizing agent such as a hydroperoxide or a peracid in an inert solvent. Examples of peracids include formic acid, peracetic acid, and perbenzoic acid. In the case of hydroperoxides, a catalytic effect can be obtained by using a mixture of tungstic acid and caustic soda with hydrogen peroxide, an organic acid with hydrogen peroxide, or molybdenum hexacarbonyl with tertiary butyl hydroperoxide. .

There is no strict limit on the amount of epoxidizing agent,
The optimal amount in each case will depend on variables such as the particular epoxidizing agent used, the degree of epoxidation desired, the particular block copolymer used, and the like.

The obtained epoxidized diene block copolymer can be isolated by a suitable method, for example, a method of precipitating with a poor solvent, a method of putting the polymer into hot water with stirring, and removing the solvent by distillation. It can be performed by a direct solvent removal method or the like.

The MFR value of the epoxidized diene block copolymer (B) used in the present invention (measurement conditions; ASTM
D1238, 230 ° C, under a load of 2.16 kg) is 13 or less in MFR ratio with respect to the MFR value of the nonpolar α-olefin resin. Here, when the MFR ratio is larger than 13, the shearing force at the time of kneading decreases, the particle size of the dispersed phase in the molded body increases, and poor dispersion occurs, and the component (B) near the surface of the molded body When the orientation of the polymer is reduced, the coating property, which is a feature of the present invention, becomes insufficient.

(B) The epoxy group content of the epoxidized diene block copolymer is represented by the amount of oxirane oxygen in the copolymer, and the oxirane oxygen is 0.8 to 6% by mass. The epoxy group content (oxirane oxygen content)
When the amount is less than the above range, the adhesion of the coating film is not improved unless the blending amount of the component (B) is increased, and when the epoxy group content exceeds the above range, the appearance of the molded article becomes poor. It becomes bad.

The amount of the (B) epoxidized diene-based block copolymer is from 3 to 50% by mass, and preferably from 5 to 30% by mass, based on the resin composition. When the amount is less than the above range, no improvement in the adhesion of the coating film to the molded product is observed, and when the amount exceeds the above range, the appearance of the molded product becomes poor.

[Thermoplastic Resin Composition] The thermoplastic resin composition of the present invention comprises (A) 50 to 97% by mass of the nonpolar α-olefin resin and (B) epoxidized diene block copolymer 3. -50 mass%, preferably 5-50 mass%
And containing. (Here, the total of the component (A) and the component (B) is 100% by mass.) The thermoplastic resin composition of the present invention may be optionally used as long as the effects of the present invention are not impaired. Other non-epoxidized thermoplastic elastomers, various inorganic fillers, various additives and the like may be appropriately contained.

Examples of the non-epoxidized thermoplastic elastomer include diene rubbers such as polybutadiene, styrene-butadiene copolymer, polyacrylonitrile-butadiene copolymer, polyisoprene, ethylene-α-olefin copolymer, ethylene- Non-diene rubber such as α-olefin-polyene copolymer, styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer, ethylene-propylene elastomer, styrene-grafted ethylene-propylene elastomer, ethylene-based ionomer resin, Styrene-isoprene block copolymer, hydrogenated styrene-isoprene block copolymer and the like can be mentioned. These elastomers can be used alone or in combination of two or more.

Specific examples of the inorganic filler include natural silicates or silicates such as fine powder talc, kaolinite, calcined clay, pyrophyllite, sericite, wollastonite, precipitated calcium carbonate, and heavy minerals. Carbonates such as calcium carbonate and magnesium carbonate, hydroxides such as aluminum hydroxide and magnesium hydroxide, oxides such as zinc oxide, zinc white and magnesium oxide, hydrous calcium silicate, hydrous aluminum silicate, hydrous silicic acid, silicic anhydride, etc. Powdered filler such as silicic acid or silicate; Flaked filler such as mica; Basic magnesium sulfate whisker, calcium titanate whisker, aluminum borate whisker, sepiolite, PMF (ProcessedMinera
and fibrous fillers such as zinotrite, potassium titanate, and elestadite; balloon-like fillers such as glass balun and fly ash balun; and mixtures thereof. Of these, talc is preferably used.

The inorganic filler, especially talc, may be untreated or surface-treated in advance. Examples of the surface treatment include, specifically, chemical or physical treatment using a treating agent such as a silane coupling agent, a higher fatty acid, a fatty acid metal salt, an unsaturated organic acid, an organic titanate, a resin acid, or polyethylene glycol. Is mentioned.

The above additives include antioxidants such as phenol-based antioxidants, sulfur-based antioxidants and phosphorus-based antioxidants; hydrochloric acid absorbers; heat stabilizers; light stabilizers; lubricants; Nucleating agents such as aluminum salts, aromatic phosphate salts, dibenzylidene sorbitol, etc .; UV absorbers; antistatic agents; flame retardants; pigments, dyes; dispersants; copper damage inhibitors; neutralizing agents; A bubble preventing agent; a crosslinking agent; a flow improver such as a peroxide; a weld strength improver.

[Production of Thermoplastic Resin Composition] The thermoplastic resin composition of the present invention comprises the components (A) and (B), the non-epoxidized thermoplastic elastomer, various inorganic fillers, and various additives. After simultaneously or sequentially inserting and kneading the agents into, for example, a Henschel mixer, a V-type blender, a tumbler blender, a ribbon blender, etc., they are melt-kneaded with a single-screw extruder, a multi-screw extruder, a kneader, a Banbury mixer, or the like. Obtained by

In particular, it is preferable to use a device having excellent kneading performance such as a multi-screw extruder, a kneader, a Banbury mixer or the like, since a high-quality thermoplastic resin composition in which each component is more uniformly dispersed can be obtained. .

In the present invention, a composition may be prepared by simultaneously mixing and kneading the respective components. Alternatively, after a preliminary mixture (master batch) containing a specific component, for example, an inorganic filler at a high concentration, is prepared, Next, the inorganic filler may be appropriately diluted with the component (A) and the component (B) so that the inorganic filler finally has a desired concentration.

As a method for producing a molded article obtained by molding the thermoplastic resin composition of the present invention into a predetermined shape, a conventionally known method can be used. As a preferable method, an injection molding method can be used.

The molded article obtained by molding the thermoplastic resin composition of the present invention into a predetermined shape can be obtained by mixing (A) a polar group-containing (B) epoxidized diene-based block into a non-polar α-olefin-based resin to be a matrix layer. The polymer is well dispersed,
Furthermore, by immobilizing (B) the epoxidized diene-based block copolymer near the surface of the molded article in the molding step, the surface polarity is improved, and the adhesion to the paint is improved.

The method for applying the primer and the paint to the molded article obtained by molding the thermoplastic resin composition of the present invention into a predetermined shape is not particularly limited, and a known coating apparatus such as a bar coater may be used. It can also be performed simply by spray application. After applying and drying the primer, a top coat can be applied to the surface by a method such as electrostatic coating, spray coating, or brush coating. Examples of the overcoat paint include an acrylic resin paint, a polyester resin paint, an acrylic-modified alkyd resin paint, an epoxy resin paint, a urethane resin paint, and a melamine resin paint. After applying the paint, follow the usual method of heating with nichrome wire, infrared, high frequency, etc.
By curing the coating film, a molded article having the desired coating film on the surface can be obtained.

[0041]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

Component (A) used in Examples and Comparative Examples,
The component (B) and the non-epoxidized thermoplastic elastomer are described below. (A) Non-polar α-olefin resin ・ A1: Polypropylene block copolymer (manufactured by Grand Polymer Co., Ltd .: J708, MFR = 45 g / 10 min) ・ A2: Homopolypropylene (Grand Polymer Co., Ltd.)
A3: Homopolypropylene (manufactured by Sumitomo Chemical Co., Ltd.): J106, MFR = 25 g / 10 min.
H501, MFR = 3 g / 10 min. A4: Homopolypropylene copolymer (manufactured by Grand Polymer Co., Ltd .: J108, MFR = 40 g / 10 min.) A5: Polyethylene (manufactured by Tosoh Corporation: Petrocene 2)
03, MFR = 15 g / 10 min) (B) Epoxidized diene block copolymer B1: Styrene-butadiene-styrene block copolymer (aromatic vinyl unit content = 40% by mass) with oxirane oxygen concentration of 3. Epoxidation was carried out with peracetic acid so as to be 0% by mass to obtain an epoxidized product. This was designated as B1. M
FR was 11 g / 10 minutes. B2: An epoxidized product was obtained by epoxidizing a styrene-butadiene-styrene block copolymer (aromatic vinyl unit content = 70% by mass) with peracetic acid so that the oxirane oxygen concentration became 2.0% by mass. This was designated as B2. M
FR was 6 g / 10 min. B3: An epoxidized product was obtained by epoxidizing a styrene-butadiene-styrene block copolymer (aromatic vinyl unit content = 35% by mass) with peracetic acid so that the oxirane oxygen concentration became 3.3% by mass. This was designated as B3. M
FR was 2 g / 10 minutes. ○ Non-epoxidized thermoplastic elastomer ・ SBS: Styrene butadiene block copolymer (MF
R = 13 g / 10 min) SEPS: hydrogenated styrene isoprene block copolymer (MFR = 70 g / 10 min) SEBS: hydrogenated styrene butadiene block copolymer (MFR = 6 g / 10 min) ○ Inorganic filler: Talc (manufactured by Hayashi Chemicals, micellar tone, average particle size = 1.4 μm).

(Examples 1 to 13) The above components were blended in the proportions shown in Table 1, mixed with a Hensyl mixer, and kneaded at 230 ° C with a twin screw extruder to obtain a thermoplastic resin composition. Was. And, the MFR of the obtained thermoplastic resin composition
ASTM D1238 (230 ° C, 2.16 kg load)
It was measured according to.

Next, the obtained thermoplastic resin composition is
Using an injection molding machine, cylinder temperature 230 ° C, mold temperature 4
At 0 ° C., a test piece (80 mm × 15 mm ×
2 mm). The test piece was evaluated for coating film adhesion. Table 1 shows the evaluation results.

(Comparative Examples 1 to 5) The above components were blended in the proportions shown in Table 2, mixed with a Hensyl mixer, and kneaded at 230 ° C with a twin screw extruder to obtain a thermoplastic resin composition. Was. Then, the MFR of the obtained thermoplastic resin composition was measured in accordance with ASTM D1238 (230 ° C., 2.16 kg load).

Next, the obtained thermoplastic resin composition is
Using an injection molding machine, cylinder temperature 230 ° C, mold temperature 4
At 0 ° C., a test piece (80 mm × 15 mm ×
2 mm). The test piece was evaluated for coating film adhesion. Table 2 shows the evaluation results.

(Evaluation method of each physical property) (1) Evaluation of paintability: "RB-
109 "(manufactured by Nippon Bee Chemical Co., Ltd.) so as to have a thickness of 10 to 20 [mu] m, and dried at 80 [deg.] C. for 15 minutes. Subsequently, a urethane paint “R212” (manufactured by Nippon Bee Chemical Co., Ltd.) was applied as a paint so as to have a thickness of 15 to 25 μm, and set at room temperature for 20 minutes. Then, clear paint “R288” (manufactured by Nippon Bee Chemical Co., Ltd.) was applied to 30 to 40 μm.
m, set at room temperature for 10 minutes, and then heated at 80 ° C. for 30 minutes. After that, the test piece was
The film was allowed to stand at 5 ° C. for 48 hours, and a cross-cut peeling test was performed to evaluate the adhesion of the coating film. The evaluation results are shown in the table with ○ △ × shown below. ：: No peeling was observed in the coating film. Δ: Peeling was observed in a part of the coating film. ×: Peeling was observed in more than half of the coating film.

(2) Warm water resistance: A coated body of a test piece obtained in the same manner as in the above (1) was immersed in warm water of 50 ° C. for 24 hours, and then subjected to a cross-cut peeling test to check the adhesion of the coating film. evaluated.
The evaluation results are shown in the table with △ x as in (1).

(3) Evaluation of appearance: The coated body of the test piece obtained by the same method as in the above (1) was visually judged according to the following criteria.
(The term “flow mark” here refers to a staggered pattern that is generated perpendicular to the injection flow path.) ○: No flow mark is observed. ×: Flow mark occurred.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

The resin composition of the present invention has excellent adhesion (paintability) of a coating film, and the molded product of the resin composition is suitable as an automobile part, a home appliance part, an industrial part, or a daily necessity. .

Claims (5)

[Claims] (A) a non-polar α-olefin resin,
(B) a melt flow rate (under measurement conditions of 230 ° C. under a load of 2.16 kg) of the component (A) and the component (B), which comprises an epoxidized diene-based block copolymer (component (A) / component) (B)) a thermoplastic resin composition having 13 or less. 2. The method according to claim 1, wherein (A) the non-polar α-olefin resin is 5
The amount of (B) the epoxidized diene copolymer is 3 to 50% by mass (the total of (A) and (B) is 100% by mass) at 0 to 97% by mass. Thermoplastic resin composition. 3. The thermoplastic resin composition according to claim 1, wherein (B) the epoxidized diene-based block copolymer has 0.8 to 6% by mass of oxirane oxygen. . 4. A molded article obtained by molding the thermoplastic resin composition according to claim 1 into a predetermined shape. 5. A coated article of a molded article obtained by coating a molded article obtained by molding the thermoplastic resin composition according to claim 4 into a predetermined shape.