JPS6128547A - Coating resin composition - Google Patents

Abstract

PURPOSE:The thermoplastic titled composition which has excellent flexibility, low-temperature impact resistance, moldability, and coating properties, consisting of a specified hydrogenated derivative of a block copolymer and a specified ethylene (co)polymer or propylene (co)polymer. CONSTITUTION:A block copolymer of the formula (where A is a monovinyl-substituted aromatic hydrocarbon polymer block; B is an elastomeric conjugated- diene polymer block; n is 1-5) obtained by the block polymerization of a monovinyl-substituted aromatic hydrocarbon and a conjugated diene monomer in an inert solvent in the presence of an Li catalyst or a Ziegler catalyst is hydrogenated in an inert solvent in the presence of a hydrogenation catalyst to give a hydrogenated derivative (a) of the aforementioned block copolymer having a Brookfield viscosity (20wt% solution in toluene, 25 deg.C) of 80cP or higher. Then 100pts.wt. component (a) and 30-400pts.wt. ethylene (co)polymer having an MI of 1-50 or propylene (co)polymer having an MFR (230 deg.C, 2.16kg load) of 3g/ 10min or higher (b) are compounded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a thermoplastic resin composition that has excellent flexibility, low-temperature impact resistance, moldability, and excellent paintability, and particularly relates to a thermoplastic resin composition that is excellent in flexibility, low-temperature impact resistance, moldability, and paintability. This invention relates to a resin composition.

In recent years, thermoplastic nystomers (hereinafter abbreviated as TPE), which have excellent flexibility, impact resistance, and moldability, have attracted attention as materials for automobile parts and home appliance parts.

[Conventional technology]

Currently, various types of TPE such as polyolefin-based, polyurethane-based, polyester-based, polystyrene-based, and polyvinyl chloride-based polymers have been developed and are commercially available.

Among these, polystyrene-based TPEs such as styrene-butadiene block polymer (SBS) and styrene-isoprene block polymer (SIS) are highly flexible, have good mechanical strength, and The resulting TPE composition has excellent processability. However, since these polymers have double bonds as conjugated diene blocks in their molecules, they have problems in heat aging resistance (thermal stability) and weather resistance.

By hydrogenating the intramolecular double bonds of a pro-copolymer of styrene and a conjugated diene, a di-distomer with improved thermal stability can be obtained.

The production of such hydrogenated poly0.7 copolymers is described in 1, for example, Japanese Patent Publication No. 42-8704 and Japanese Patent Publication No. 43-663.
No. 6) B! ! J Publication No. 45-20504, Special Publication No. 48-
It is described in each specification such as No. 3555. In addition, several proposals have been made regarding TPE compositions using these hydrogenated substances, such as JP-A-50-14742;
JP-A-52-6J551 and other specifications disclose compositions in which a hydrogenated styrene/conjugated diene block copolymer is blended with a hydrocarbon oil and an α-olefin polymer.

[Problem that the invention seeks to solve]

However, the TPE composition using the above-mentioned hydrogenated block copolymer of styrene and conjugated diene does not necessarily give a good coating film when molded as an exterior part and painted. When baking paint is applied, there is a problem in that blisters often occur, which significantly impairs the appearance of the product.

[Means for solving problems]

The present inventors conducted various studies to improve the coating properties of compositions using hydrogenated styrene conjugated diene-block copolymers as described above, and found that a hydrogenated styrene conjugated diene block copolymer has been developed. By blending this with an α-olefin polymer or copolymer, we succeeded in obtaining a TPE composition with excellent mechanical properties and processability as well as excellent paintability.

That is, the present invention provides (a) general formula A-(-B-A)n
(Here, A is a monovinyl-substituted aromatic hydrocarbon polymer, B is a conjugated diene elastomeric polymer block, and n is an integer from 1 to 5.) is a hydrogenated derivative, and the pull and cut viscosity of a 20% by weight toluene solution at 25°C is 80.
This is a paintable resin composition characterized by comprising 100 parts by weight of a resin having a particle size of 0 centipoise or more and (b) an ethylene-based, propylene-based polymer or copolymer resin, or a mixture thereof.

Component (a) The monovinyl-substituted aromatic hydrocarbon monomer constituting the polymer block A of the block copolymer to be hydrogenated in the hydrogenated derivative used in component (a) in the present invention is preferably It is styrene, and α-methylstyrene and the like are also used. The conjugated diene monomer in polymer block B is preferably butadiene or isoprene, and
A mixture of both may be used. When butadiene is used as the single conjugated diene monomer to form polymer Pro, B, the block copolymer retains diistomeric character after being hydrogenated to saturate the double bonds. In order to achieve this, it is preferable to adopt polymerization conditions such that the 1,2-microstructure in the microstructure in the polybutadiene block is 20 to 50, more preferably 7 or 1,2-microstructure. The size is 35-45 inches.

Many methods have been proposed for producing these block copolymers, but a typical method is, for example, the method described in Japanese Patent Publication No. 40-2.3798, using a lithium catalyst or Ziegler catalyst. Using a type catalyst,
It can be obtained by block polymerization in an inert solvent.

The hydrogenation treatment of these block copolymers is carried out in an inert solvent by the method described in the specifications of Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, or Japanese Patent Publication No. 46-20814. Hydrogenation is carried out in the presence of a catalyst without the addition of water. In this hydrogenation, polymer block B
At least 50%, preferably 80 or more, of the olefinic double bonds in the polymer block A are hydrogenated, and up to 25 of the aromatic unsaturated bonds in the polymer block A are hydrogenated.

One such hydrogenated block copolymer is commercially available from Shell Chemical Company under the trade name "rKRATON-G".

As component (a) used in the present invention, a 20% by weight toluene solution of such a hydrogenated derivative having a Brookfield viscosity of 800 centipoise or more at 25° C. is used. This Brookfield viscosity is 80
If a coating with a centipoise lower than 0 centipoise is used, the paintability of the molded product will be greatly deteriorated.

Component (b) Component (b) used in the present invention is an ethylene polymer or copolymer resin, a propylene polymer or copolymer resin, or a mixture thereof. As the ethylene resin, low density polyethylene, medium/high density polyethylene, high density polyethylene or ethylene/vinyl acetate copolymer resin is used. A load of about 1 to 50 can be used. As the propylene resin, in addition to a propylene homopolymer, a propylene copolymer resin containing 30% by weight or less of a comonomer such as ethylene is used. MFR of propylene resin (230°(,2,1
6KF load) is 3 f/10 minutes or more, preferably 5 to 2
007'/10 minutes, preferably 10-100. P/
10 minutes is used. Ethylene resin and propylene resin may be used in combination.

The amount of component (b) to be blended is 30 to 400 parts by weight per i o o parts by weight of component (a); if the blend is less than 30 parts by weight, the moldability of the composition will be poor; If the ratio exceeds the above, the rigidity of the composition will become too high and the impact resistance at low temperatures will deteriorate. The preferred blending amount is 60 to 20
It is 0 parts by weight.

The composition of the present invention may contain inorganic fillers such as glass fiber, talc, calcium carbonate, mica, etc. within a range that does not significantly impair the effects of the present invention. In addition, as is done for ordinary resin compositions, pigments,
Additives such as heat stabilizers, antioxidants, and ultraviolet absorbers can be added.

Composite The composition of the present invention is obtained by compounding the above-mentioned components, and the blending ratio of each component is selected depending on the intended use of the resulting composition.

The compounding can be carried out by a commonly used cross-wire system such as a screw extruder, twin screw extruder, Banbury mixer, roll, Prabender plastograph, kneader, etc.

[Action and effect]

The composition of the present invention can be molded using a commonly used thermoplastic resin molding machine, and molding methods such as injection molding, extrusion molding, blow molding, and calendar molding can be applied.

The molded product obtained using the composition of the present invention can be coated with, for example, a two-component urethane paint without causing blistering, and the molded product has an excellent balance between flexural elasticity and low-temperature impact resistance. Suitable for exterior parts that require painting.

Accordingly, the fields of application of the composition of the present invention include flexible pannos, side bumpers, moldings, and fissure panels.

〔Example〕

The following examples and comparative examples illustrate the invention,
This shows its effectiveness.

In these Examples and Comparative Examples, the following test methods were used for each type of evaluation.

(Re MFR (y/1 o min) JIS-7210 (23°C, 2, 1611; 1
-) (2) Flexural modulus (quasi/cd) JIS-7203 (23°C) (3) Brittleness temperature JIS-K 6750, subjected to impact at -30°C, test piece Observe the state of destruction in the garden.

Examples 1 to 4 and Comparative Examples 1 to 3 The following three types of styrene and conjugated diene were used as component (a).
A pro-copolymer hydride was used.

(a-1) SHELDA MICAL M KRATON G-1
650 Bruckfield viscosity 1500 centipoise (a-2) Same as above KRATON G-16s 1 Bruckfield viscosity: 2 ooo centipoise (a-3) Same as above KRATON G-16s 2 Bruckfield viscosity: 550 Component (b) is propylene. Ethylene copolymer resin (manufactured by Mitsubishi Yuka Co., Ltd., ethylene content 7% by weight, MFR: 4s
p/xo min) was used.

The above components were mixed in the proportions shown in Table 1 for 2 minutes using a super mixer manufactured by Kawada Manufacturing Co., Ltd., and kneaded and granulated at 220° C. using a PCM twin-screw kneader manufactured by Ikegai Iron Works. The obtained pellets were molded into test pieces at 240°C using a screw in-line injection molding machine, and the mechanical properties and paintability of each test piece were evaluated.

Paintability is 100MIIX 100mm thick test piece at 3 corners, t, x, +-)! After cleaning the surface with J chloroethane vapor, the surface treatment for painting is carried out at a low temperature.

This was done by lasma treatment. That is, microwave oven.

Lasma processing equipment (manufactured by Tokyo Shibaura Electric Co., Ltd., TMZ-9602
B) was used for 10 seconds at an oxygen gas flow rate of 400 cc/min, a pressure of 0, '5'' forr, and an output of 400 W.This test piece was coated with a two-component curable urethane paint (manufactured by Nippon B Chemical Co., Ltd., 5z-263). ) with a coating thickness of approximately 30 to 40
It was spray applied to form a μ helmet and baked at 90°C for 40 minutes. Next, this factory specimen was immersed in 40°C hot water for 200 hours, and then the degree of blistering was measured by ASTM'.
)-714-s 6. The evaluation results are shown in Table 1.

Revision of specification: (No change in content) In the comprehensive evaluation of the results shown in Table 1, the composition of Comparative Example 1 had poor paintability, and the composition of Comparative Example 2 had poor MF.
The moldability was poor based on the RO point, and Comparative Example 3 had poor impact resistance. In contrast, the composition of the present invention has excellent paintability,
Moreover, it has a good quality balance between bending elastic modulus and low-temperature impact resistance, and has good moldability.

Claims (1)

[Claims] (1) (a) General formula A-(B-A)_n (where A is a polymer block of monovinyl-substituted aromatic hydrocarbon, B is an elastomeric polymer block of conjugated diene, and n
is an integer from 1 to 5), which is a hydrogenated derivative of a block copolymer represented by
100 parts by weight of a Brookfield viscosity of 800 centipoise or more; and (b) an ethylene-based, propylene-based polymer or copolymer resin, or a mixture thereof.