JP2000219801A - Resin composition - Google Patents

Abstract

(57) [Problem] To provide a resin composition having excellent fluidity and improved impact resistance. SOLUTION: Polybutylene terephthalate (A) 10
A resin composition comprising 0 parts by weight and 0.1 to 20 parts by weight of an ethylene-α-olefin copolymer (B), wherein the effectiveness of the ethylene-α-olefin copolymer (B) particles measured by Dirichlet division is evaluated. When the range average value is Da and the standard deviation is Ds, Da × Ds <200 μm ⁴ , and the resin composition has an MFR value of 4 or more at 325 g at 250 ° C. measured by JIS K-7210A method. Composition.

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 having excellent fluidity, and more particularly to a thermoplastic polyester resin composition having excellent impact resistance.

[0002]

2. Description of the Related Art Polybutylene terephthalate (hereinafter referred to as P
(May be abbreviated as BT) is a thermoplastic material having excellent moldability and various excellent properties including solvent resistance,
It has good physical and mechanical properties by melt molding and injection molding, and is used for various applications. Typical applications among these are electrical and electronic parts
Appliance housing and automotive applications. However, the PBT resin originally has a high crystallization rate and a high degree of attained crystallinity, and thus lacks toughness. The toughness is the crack progress inside the PBT polymer, and as a method for suppressing this, a method of adding an elastomer or a method of increasing the molecular weight has been proposed.

[0003]

However, such a method has a problem that it tends to cause an excessive addition of an elastomer or the like, resulting in deterioration of fluidity. In view of the above problems, an object of the present invention is to provide a thermoplastic resin composition having excellent fluidity and excellent impact resistance.

[0004]

In view of this situation, the present inventors have conducted intensive studies on the above-mentioned problems, and as a result, when the ethylene-α-olefin copolymer dispersed in PBT has a specific particle size distribution, The present inventors have found that the composition has excellent impact resistance without impairing the fluidity of the composition, and arrived at the present invention.

That is, the present invention relates to a resin composition comprising 100 parts by weight of polybutylene terephthalate (A) and 0.1 to 20 parts by weight of an ethylene-α-olefin copolymer (B), which is measured by Dirichlet division. ethylene-
The average effective range of the α-olefin copolymer (B) particles is Da,
When the standard deviation is represented by Ds, Da × Ds <200 μm ⁴ , and the resin composition has an MFR value of 4 or more at 325 g at 250 ° C. measured by the JIS K-7210A method.

Hereinafter, the present invention will be described in detail. The polybutylene terephthalate (A) used in the present invention is a polyester containing terephthalic acid as a main acid component and 1,4-butanediol as a main glycol component. Here, the main component is at least 80 mol%, preferably 90 mol%, based on all acid components or all glycol components.
A component that accounts for the above.

[0007] Copolymerizable acid components include, for example, aromatic dicarboxylic acids other than terephthalic acid, such as isophthalic acid,
Naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ketone dicarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and the like; alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid, It is a tetralin dicarboxylic acid.

[0008] Copolymerizable glycol components include, for example, ethylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexane dimethanol, tricyclodecane dimethylol, shixylylene glycol, bisphenol A, bisphenol B, bishydroxyethoxy bisphenol A. is there.

In a range where the polyester does not substantially lose the molding performance, for example, in a range of 3 mol% or less, the polyfunctional compound,
For example, glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, and pyromellitic acid may be copolymerized.

Examples of other copolymerizable components that can be used in obtaining polybutylene terephthalate include oxyacids such as p-hydroxybenzoic acid and p-hydroxyethoxybenzoic acid.

Further, two or more kinds of polybutylene terephthalates having different molecular weights may be mixed.

As the ethylene-α-olefin copolymer (B) used in the present invention, an ethylene polymer or a copolymer of ethylene and an α-olefin having 3 or more carbon atoms (hereinafter, both are collectively referred to as ethylene-α-olefin copolymer). (It is called unmodified ethylene polymer)
Is used.

The unmodified ethylene polymer is preferably a copolymer type, and the α-olefin as a copolymer component is propylene, butene-1, hexene-1, decene-1, 4-methylbutene-1, 4-methylbutene. Methylpentene-1
Can be mentioned. Of these, propylene and butene-1 are particularly preferred. The unmodified ethylene polymer is preferably used as a modified ethylene polymer obtained by graft-polymerizing an α, β-unsaturated carboxylic acid or a derivative thereof to the unmodified ethylene polymer.

The α, β-unsaturated carboxylic acid or its acid derivative (hereinafter collectively simply referred to as α, β-unsaturated carboxylic acid) includes acrylic acid, methacrylic acid,
Examples include ethacrylic acid, maleic acid, fumaric acid, esters of the above acids, glycidyl esters, acid anhydrides and imides. Of these, glycidyl esters, maleic anhydride and maleic imide are particularly preferred.

When the amount of the α, β-unsaturated carboxylic acid to be graft-polymerized to the unmodified ethylene polymer is too large, the obtained thermoplastic polyester resin composition is colored yellow or red and only a molded article having poor appearance is obtained. Since it is not obtained, the amount to be graft-polymerized is preferably from 0.1 to 1% by weight, more preferably from 0.2 to 0.8% by weight, based on the whole modified ethylene polymer. Here, the term "graft polymerization" means that a part or all of the unmodified ethylene polymer is chemically bonded to a monomer or polymer of an α, β-unsaturated carboxylic acid or a derivative thereof.

Such a modified ethylene polymer can be easily produced by adding an α, β-unsaturated carboxylic acid to an unmodified ethylene polymer according to a conventional method, and usually melt-kneading at 150 to 300 ° C. For melt kneading, a screw type extruder is often used.

Of course, α, α * -bis-t-butylperoxy-p-
An organic peroxide such as diisopropylbenzene may be used in an amount of 0.001 to 0.05% by weight based on the unmodified ethylene polymer.

Examples of the unmodified ethylene polymer include, for example,
Using a vanadium compound such as vanadium oxytrichloride or vanadium tetrachloride and an organoaluminum compound in a low-density polyethylene or Ziegler-Natta catalyst
Those obtained by copolymerizing 0 mol% or more, preferably 50 to 95 mol% of ethylene and 50 mol% or less, preferably 20 to 5 mol% of α-olefin are exemplified. Particularly suitable as such an unmodified ethylene polymer are a series of polymers marketed by Mitsui Petrochemical Industry Co., Ltd. under the trademark Tuffmer, such as Tuffmer A-408.
5, Tuffmer A series such as Tuffmer A-4090 and Tuffmer A-20090
(Ethylene butene-1 copolymer), Tuffmer P-0180, Tuffmer P-0280, Tuffmer P-0480, Tuffmer P series (Ethylene-propylene copolymer) such as P-0680.

Ethylene-α-olefin copolymer
The blending amount of (B) is polybutylene terephthalate (A)
The amount is 0.1 to 20 parts by weight, preferably 0.1 to 10% by weight, based on 100 parts by weight. When the amount of the modified ethylene copolymer is less than 0.1 part by weight, there is no effect of improving the impact resistance, and when the amount exceeds 20 parts by weight, the rigidity is remarkably reduced, which is a problem in use as engineering plastics. Occurs.

The dispersed particles of the component (B) in the resin composition of the present invention are represented by Da × when the average effective range of the particles measured by Dirichlet division is Da and the standard deviation is Ds.
Ds <200 μm ⁴ , JIS K-7210 A
The MFR value at 325 g at 250 ° C. measured by the method must be 4 or more.

The improvement in impact resistance depends not only on the size of the dispersed particles but also on the state of dispersion. Even if the area of the dispersed particles is small, improvement in impact resistance cannot be expected if the dispersed particles are in a state of aggregation. Further, even if dispersion particles are not sufficiently small, the impact resistance can be improved as long as the dispersion state is uniform.

As a method of evaluating such a dispersion state, H.Ta
The Dirichlet division method described in Nakanaka et al, J Appl. Phys. 65 (1989) is effective. The average value of the area occupied by each dispersed particle obtained by this evaluation represents the range in which each particle can exhibit an effective effect, and the standard deviation can represent the dispersion state of each particle. If the standard deviation is small, the state is a uniform dispersion state, and if the standard deviation is large, the state is an aggregation state.

As a method for producing such uniform dispersibility, the melt viscosities of the component (A) and the component (B) at a shear rate of 300 sec ^-1 at 250 ° C. are determined by η _A and η _B , respectively.
It is preferable that the following formula (I) is satisfied. 3 <η _B / η _A <15 (I) If η _B / η _A is out of this range, it becomes difficult to disperse the component (B) particles. Further, it is necessary that the MFR value of the resin composition at 250 ° C. and 325 g measured by the JIS K-7210A method is 4 or more. When the MFR value is less than 4, the fluidity is low and the practicability is poor.

In the composition of the present invention, calcium carbonate, titanium oxide, feldspar mineral,
Granular or amorphous fillers such as clay, white carbon, carbon black and glass beads; plate-like fillers such as kaolin clay and talc; scaly fillers such as glass flakes, mica and graphite;
A fibrous filler such as glass fiber, carbon fiber, wollastonite, potassium titanate and the like may be added as long as the object of the present invention is not impaired.

Further, if necessary, a flame retardant, an antioxidant,
Other compounding agents such as a stabilizer, a colorant, a lubricant, a release agent, an ultraviolet absorber, and an antistatic agent may be added in such an amount that the effect is exhibited.

In the resin composition of the present invention, it is preferable that these components are uniformly dispersed. All or a part of the compounded components are supplied to the heated twin-screw extruder in a lump or in a divided manner, and after homogenization by melt kneading, the molten resin extruded into a wire is cooled and solidified, and then the desired length is obtained. The method of cutting into granules by cutting is preferred.

In order to obtain a resin molded product from the resin composition for molding thus produced, the resin molded product is usually supplied to a molding machine such as an injection molding machine while keeping it sufficiently dried.

[0028]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. The evaluation methods in the examples are as follows. In the tables, the units of the components constituting the composition are parts by weight unless otherwise specified.

[Production of modified EPR] Unmodified ethylene-propylene copolymer (Tuffmer P0680) 100 manufactured by Mitsui Chemicals, Inc.
Parts by weight, α, α-bis-t dissolved in a small amount of acetone
-Butylperoxy-p-diisopropylbenzene
After blending 025 parts by weight and 0.5 parts by weight of maleic anhydride in a Henschel mixer,
extruded at a cylinder temperature of 230 ° C. using a twin-screw extruder having a modified ethylene polymer (hereinafter referred to as modified E).
PR1: maleic anhydride copolymerization amount: 0.33% by weight).

Α, α-bis-t-butylperoxy-p-diisopropylbenzene dissolved in 100 parts by weight of unmodified ethylene-propylene copolymer (Tuffmer P0680) manufactured by Mitsui Chemicals, Inc. After blending 025 parts by weight and maleic anhydride 1.0 part by weight in a Henschel mixer, the mixture was extruded at a cylinder temperature of 230 ° C. using a twin-screw extruder having a screw diameter of 44 mm and pelletized to obtain a modified ethylene polymer (hereinafter, modified EPR2). Notation: maleic anhydride copolymerization amount 0.66% by weight).

[Examples 1 to 6, Comparative Examples 1 to 6] Intrinsic viscosity
0.70 dl (in orthochlorophenol at 35 ° C)
/ G of polybutylene terephthalate (hereinafter PBT-
A), intrinsic viscosity (35% in orthochlorophenol)
C) is 1.05 dl / g (hereinafter referred to as PBT-B), Tuffmer P0680 as an impact modifier, the modified EPR1 and the modified EPR mentioned above.
2 was uniformly premixed in the ratio (parts by weight) shown in the table, and melt-kneaded into pellets at a barrel temperature of 250 ° C. using a twin-screw extruder having a screw diameter of 44 mm under the conditions shown in the table. The obtained pellets were pre-dried at 130 ° C. for 5 hours, injection molded, and evaluated for physical properties by the methods described below.

[Evaluation method] [Measurement of melt viscosity at a shear rate of 300 sec ^-1 ]
PBT-A, P dried with a hot air dryer at 30 ° C for 5 hours
BT-B and an undried ethylene-α-olefin copolymer were subjected to an elevated flow tester C manufactured by Shimadzu Corporation.
Using FT-500, measurement temperature 250 ° C, die L / D =
10/1 mm, by changing the load under the condition of preheating time of 300 seconds, a data which is obtained by measuring the data before and after 5-point shear rate of 300 sec ^-1 subjected to fitting by the least square method shear rate 300 sec ^{- The} melt viscosity according to ¹ was determined.

[Impact strength] A molded product specified by ASTM D256 was subjected to a mold clamping force of 60 t and a cylinder capacity of 145 c.
m using an injection molding machine with a cylinder temperature of 260 ° C., a mold temperature of 80 ° C. and a total molding cycle of 45 seconds. To obtain a test piece. ASTM
The impact strength was evaluated according to -D256.

[Fluidity] According to the MFR test method specified by JIS K-7210A, the MFR value of the resin composition at a measuring temperature of 250 ° C. and a load of 325 g was measured to determine the fluidity.

[Measurement of Effective Range of Particles by Dirichlet Splitting Method] A test piece whose impact strength was measured was heat-treated in xylene heated to 140 ° C. for 3 hours to dissolve the impact modifier component. The fracture surface of this test piece was observed with an electron microscope.
The electron microscope used was JSM-6100 manufactured by JEOL Ltd. Three photographs were taken at a magnification of 2000 times per sample. The obtained image was subjected to Dirichlet division using the image processing software Image Hyper2 manufactured by Interquest Co., Ltd. The method of Dirichlet partitioning is described in (H. Tanaka et al, J Appl.
hys. 65 (1989)). The image of the dispersed particles was subjected to a 4-neighbor exclusive dilation process and divided into occupied areas of each particle. After determining the logical difference between the original dispersed particle images from the obtained image of the occupied range, the portion in contact with the frame was removed. The area of each region of this image was determined and defined as the effective range of each particle. FIG. 1 shows an image after Dirichlet division according to the first embodiment.

[0036]

[Table 1]

[0037]

According to the present invention, it is possible to provide a polyester resin composition having excellent fluidity and improved impact resistance.

[Brief description of the drawings]

FIG. 1 is an image after Dirichlet division according to a first embodiment.

Claims (1)

[Claims] 1. Polybutylene terephthalate (A) 10
0 parts by weight and ethylene-α-olefin copolymer (B)
A resin composition comprising 0.1 to 20 parts by weight, wherein the average effective range of the ethylene-α-olefin copolymer (B) particles measured by Dirichlet division is Da, and the standard deviation is D.
s is Da × Ds <200 μm ⁴ , and the resin composition was measured by a JIS K-7210A method of 250.
A resin composition having an MFR value of 4 or more at 325 g at ℃.