JPH0251551A - Resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition having a rigidity of a small temperature dependency and improved impact resistance, etc., by mixing a crystalline ethylene/propylene block copolymer with a specified hydrogenated block copolymer and crystalline PE. CONSTITUTION:30-85 pts.wt. crystalline ethylene/propylene block copolymer (a) of an ethylene content of 5-20wt.%, a boiling n-heptane extraction residue >=70wt.% and an MFI (230 deg.C) of 1-100 is mixed with 20-60 pts.wt. hydrogenated block copolymer (b) composed of at least one polymer block A based on a vinylaromatic compound and at least one polymer block B based on a hydrogenated conjugated diene compound and having a number-average MW of 5000-100000 and 5-35 pts.wt. crystalline PE (C) of a density >=0.945g/cm<3> and an MI (190 deg.C) of 1-50 in such amounts that the total of components A and C is 40-80 pts.wt. and the ratio of component A to component C is 90-50/10-50.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polypropylene-based resin composition having low temperature dependence of stiffness, moderate stiffness, surface hardness, and high impact strength properties. More specifically, for applications such as ski boots that require properties to be maintained over a wide range of temperatures from low to high temperatures, or for industrial parts such as automobiles and home appliance parts that require similar properties. This invention relates to extremely useful resin materials.

[Conventional technology]

Polypropylene has an excellent balance of rigidity, heat resistance, sweat and impact resistance, hardness, etc., and is inexpensive, so it is widely used as a general-purpose resin in automobile parts, home appliance parts, food packaging materials, general miscellaneous goods, etc. has been done. The drawback of this polypropylene is that it is poor in low-temperature properties, particularly low-temperature impact resistance, and as an improved type, a grade copolymerized with ethylene has been commercially available.

However, even these copolymer types cannot be said to have sufficient impact resistance, so many attempts have been made to improve the impact resistance (including low temperature) by adding various elastomers to polypropylene. As one example, a hydrogenated vinyl aromatic compound-conjugated diene compound block copolymer is used. (Tokuko Showa 4i-
(Japanese Patent Publication No. 2909, Japanese Patent Publication No. 55-18739) Furthermore, various polymers and additives may be added as a third component to a composition consisting of polypropylene and a hydrogenated vinyl aromatic compound-conjugated diene compound block copolymer. Many of the added compositions are also known, for example, JP-A-Shoei-z
76a4o@ publication discloses a composition containing a filler and/or an ethylene copolymer for the purpose of improving paintability, and JP-A-61-152752 discloses a composition containing a filler and/or an ethylene copolymer.
A composition is disclosed that has a balance between heat sealability and ease of tearing, in which an ethylene polymer having a density of 0.890 to 0.940'J/cm3 is added.

Furthermore, JP-A-61-215643, JP-A-61-
No. 72039 and Japanese Unexamined Patent Publication No. 61-69848 disclose compositions containing inorganic fillers and fibrous fillers.

In addition to these, compositions containing polystyrene resin (Japanese Unexamined Patent Publication No. 56-38338@) and polycarbonate resin (Japanese Unexamined Patent Publication No. 61-115945) as a third component have been disclosed.

In addition, as a composition containing a block copolymer as a main component, JP-A-61-28547 discloses a composition containing an ethylene-based and/or propylene-based polymer that has excellent paintability. , a similar composition is disclosed in JP-A No. 6
It is also disclosed in Publication No. 2-84143@.

[Problem to be solved by the invention]

Many of the conventional technologies described above are based on polypropylene, and are made by adding a hydrogenated vinyl aromatic compound-conjugated diene compound block copolymer or a third component to improve its impact resistance, paintability, etc. However, when trying to improve impact resistance, especially at low humidity, the overall stiffness decreases, and the temperature dependence of polypropylene's inherent stiffness (for example, high temperature stiffness/
There was no improvement in the normal humidity stiffness ratio or the low temperature stiffness/room temperature stiffness ratio.

On the other hand, market requirements are becoming more stringent, and there is an extremely high need for materials whose physical properties and texture do not change much over a wide temperature range from low to high temperatures.

For example, in ski boots that are generally used at room temperature to low temperatures, in addition to rigidity and resistance to scratches at room temperature to high temperatures (for example, when dry), it is not enough to simply avoid problems such as slippage at low temperatures. It is required to be softer even at low temperatures.

The present inventors conducted extensive studies in order to obtain a composition that maintains as much of the excellent properties of polypropylene as possible and also reduces the temperature dependence of rigidity, which is a drawback of polypropylene.

[Means to accomplish the task]

A composition in which a hydrogenated vinyl aromatic compound-conjugated diene block copolymer is added to polypropylene (including copolymers) has a lower absolute value of stiffness than the original polypropylene, but the stiffness? The fJM dependence did not change significantly.

Therefore, the present inventors conducted an investigation into improvements using a third component, and unexpectedly found that an ethylene propylene block copolymer was used as the polypropylene, and crystals with a density of 0.945'j/cm3 or more were used as the third component. We have discovered that only in compositions using polypropylene and blending each component in specific proportions can the temperature dependence of rigidity be reduced while maintaining the good properties of polypropylene (high temperature properties, hardness).

Such an effect was noticeable (but did not appear) when a homopolymer or random copolymer was used as the polypropylene.

Furthermore, when polyethylene with low density is used, the overall rigidity decreases and the properties of polypropylene are lost.

Furthermore, the effects of the present invention could not be obtained when ethylene-propylene rubber or the like was used instead of the hydrogenated vinyl aromatic compound-conjugated diene compound block copolymer of the present invention.

The composition of the present invention also has the unique effect that the temperature dependence of its stiffness is small compared to various combinations in which the ratio of propylene and ethylene is the same in the final composition (for example, using polypropylene homopolymer). There were many things.

Based on the above results, the physical properties of the final composition are as follows:
Flexural modulus of elasticity is 5,000 to 10,000 Kg/ci, and the temperature dependence of rigidity is small (as an index, 23°C and -40°C
(SL/N), 23°C and 50'C (St-1/N)
The following invention has been achieved as a composition that achieves high impact properties and surface hardness with a ratio of flexural modulus of 2.5 or less and 0.5 or more, respectively.

In other words, the present invention comprises 30 to 85 parts by weight of a crystalline ethylene propylene block copolymer, at least one polymer block A mainly composed of a vinyl aromatic compound, and a hydrogenated conjugated diene compound. Hydrogenated block copolymer consisting of at least one polymer block B as a main component 20~
60 parts by weight and 5 to 35 parts by weight of crystalline polyethylene having a density of 0.945'J/cm3 or more, a total of 100 parts by weight.

A crystalline ethylene propylene block copolymer is used as the polypropylene of the present invention. This crystalline ethylene propylene block copolymer has a small temperature dependence of stiffness, and in order to maintain appropriate stiffness and high impact temperature characteristics, the ethylene content is 5 to 20% by weight, and the boiling n-hebutane extraction residue is content is 70% by weight or more, and the melt flow index (230° C.) is 1 or more and 100 or less, preferably 8 or more and 50 or less in order to maintain moldability for molding products as a resin composition.

The hydrogenated block copolymer has at least one polymer block A mainly composed of a vinyl aromatic compound and at least one hand-coalesced block B mainly composed of a hydrogenated conjugated diene compound, - For example, one having the following structure,
Or a mixture of these.

A-(-B-A>, , B+A-B> n, (A-B)
(A-B>X, (B-A-B>Xn'
m mHere, n=1 to 3,
m=2~4, X is the remaining base of the coupling agent.

The hydrogenated block copolymer contains 5 to 9 vinyl aromatic compounds.
5% by weight, preferably 15 to 60% by weight. Furthermore, the polymer block A mainly composed of a vinyl aromatic compound is a vinyl aromatic compound motor vehicle combined block or a vinyl aromatic compound containing 50% by weight or more, preferably 7% by weight.
The block is a copolymer block of a vinyl aromatic compound containing 0% by weight or more and a hydrogenated conjugated diene compound, and the polymer block B mainly consists of a hydrogenated conjugated diene compound. or a copolymer of a hydrogenated conjugated diene compound and a vinyl aromatic compound containing 50% by weight or more, preferably 70% by weight or more of a hydrogenated conjugated diene compound. It is a block.

In addition, if the polymer block A mainly composed of a vinyl aromatic compound and the polymer block B mainly composed of a hydrogenated conjugated diene compound are copolymer blocks, The distribution of the hydrogenated conjugated diene compound or vinyl aromatic compound in the molecular chain may be random, highly birded (increasing or decreasing 1,000 mm component along the molecular chain), partially blocky, or any combination of these. If there are two or more polymer blocks J3 mainly composed of a vinyl aromatic compound and two or more polymer blocks mainly composed of a hydrogenated conjugated diene compound, each block has the same structure. There may be one, and it may have a different structure.

As the vinyl aromatic compound constituting the hydrogenated block copolymer, one or more types are selected from, for example, styrene, α-methylstyrene, vinyltoluene, p-tert-butylsdyrene, etc. Among them, styrene is selected. Particularly preferred. In addition, as a co-19 diene compound before hydrogenation to obtain a hydrogenated conjugated diene compound,
For example, butadiene, isoprene, 1,3 pentadiene,
One or more types are selected from 2,3 dimedyl, 1,3 butadiene, etc., and among them, butadiene, isoprene, and a combination thereof are preferred. Before hydrogenation, the microstructure of a polymer block mainly composed of a conjugated diene compound can be arbitrarily selected; for example, in a polybutadiene block, 1,2 bonds are 20 to 50%, Preferably it is 25 to 45%.

The number average molecular weight of the hydrogenated block copolymer is 5,000 to 1
00,000. Preferably io, ooo~500.00
0, more preferably in the range of 30.000 to 200.000. Furthermore, the molecular structure of the hydrogenated block copolymer is
It may be linear, branched, radial, or any combination thereof.

The hydrogenated block copolymer of the present invention may be produced by any method as long as it has the above-mentioned structure; examples thereof include Japanese Patent Publication No. 40-23798.

The crystalline polyethylene of the present invention has a density of 0.945 g/cm3 or more in order to achieve appropriate rigidity, high surface hardness, and impact strength characteristics among low-density polyethylene and medium-high density polyethylene produced by high-pressure method or medium-low pressure method. Among them, it is necessary to use high-density polyethylene, and from the viewpoint of moldability for molding products as a resin composition, the melt index (190°C) is 1 to 50, preferably 2.
Must be 5 or more and 30 or less. If the density of crystalline polyethylene is lower than 0.945 g/cm3, the surface hardness will be low compared to the achieved rigidity, making it practically unusable.

The crystalline ethylene propylene block copolymer is used in an amount of 30 to 85 parts by weight, preferably 3 parts by weight based on 100 parts by weight of the total resin composition.
It is contained in an amount of 5 to 80 parts by weight. If the content is less than 30 parts by weight, it is not preferable from the viewpoint of maintaining the appropriate rigidity that is the aim of the present invention, particularly at high temperatures above room temperature. 8 again
If the amount exceeds 5 parts by weight, the stiffness will increase, especially at low temperatures below room temperature, and further 't1! I? i! It is also unfavorable from the viewpoint of maintaining characteristics.

The hydrogenated block copolymer is contained in the total resin composition in an amount of 20 to 60 parts by weight, preferably 25 to 50 parts by weight. If the content is less than 20 parts by weight, it is not preferred from the viewpoint of maintaining appropriate flexibility and impact properties at low temperatures below room temperature. Further, if the amount exceeds 60 parts by weight, it is not preferable from the viewpoint of maintaining appropriate rigidity, particularly at high temperatures above room temperature, and is also undesirable because the surface hardness decreases significantly.

5 to 35 parts by weight of crystalline polyethylene in the total resin composition,
Preferably it is contained in a small amount of 10 to 35 parts. If the content is outside the above range, the stiffness at temperatures lower than room temperature will become too large, and it is not preferable to maintain an appropriate stiffness.

The resin composition of the present invention can be achieved by combining the above-mentioned components in amounts within the ranges. That is, the resin composition of the present invention contains the above components, 30 to 85 parts by weight of a crystalline ethylene propylene block copolymer, 20 to 60 parts by weight of a hydrogenated block copolymer, and 100 parts by weight of the resin composition. This can be achieved by containing 5 to 35 parts by weight of polyethylene.

The resin composition of the present invention can be achieved by combining the above-mentioned components in amounts within ranges, but more preferably, the amount of crystalline ethylene propylene block copolymer and crystalline polyethylene in 100 parts by weight of the resin composition of the present invention is The total amount of h4N is 40 to 80 small parts, preferably 50 to 85 parts by weight,
When the ratio of crystalline ethylene propylene to crystalline polyethylene is 90/10 to 50,150, a resin composition with low temperature dependence such as rigidity, which meets the object of the present invention, can be obtained.

The resin composition of the present invention consists of each of the above-mentioned essential components, but in many cases, antioxidants, ultraviolet absorbers, light stabilizers, pigments, and moldability improvers are added according to the examples commonly used for thermoplastic resins. etc. can be added and used.

Furthermore, an inorganic filler may be added as long as it does not impair the temperature dependence of rigidity, appropriate rigidity, impact properties, and maintenance of surface hardness, which are the objectives of the present invention.

The resin composition of the present invention can be produced by uniformly mixing and kneading thermoplastic resins by a method commonly used for mixing and kneading thermoplastic resins. Examples include mixing and kneading using a -shaft or two-shaft extruder, and the above-mentioned components are fed into the hopper of a molding machine commonly used for molding thermoplastic resins, such as an injection molding machine. , a method of mixing and kneading in the molding machine and immediately molding may be used, and mixing and kneading by the above-mentioned method is not recommended.

The above-mentioned components of the composition of the present invention may be mixed and kneaded simultaneously, or after mixing and kneading two components, the remaining components may be mixed and kneaded.
Various mixing and kneading procedures such as a method of mixing and kneading the components can be used, but there are no restrictions on the method.

What is required in this case is to select a temperature condition that is higher than the melting humidity and lower than the deterioration and decomposition temperature of each of the above-mentioned components of the different systems, and generally 190°C to 270°C is recommended.

(Effects of the Invention) The composition of the present invention obtained by the above-described method has low temperature dependence of stiffness, has appropriate stiffness, good impact properties, and surface hardness, and can be used in a wide range of humidity such as the above-mentioned ski boots. It can be used as a material in cases where small changes in physical properties are required over a certain area.

Furthermore, the composition of the present invention also has the feature that stress generated due to temperature changes is small.

This is extremely useful when combining different materials or assembling @ manufacturing, and this property can be used as a material for industrial parts such as automobile parts and home appliance parts. is wide.

The production of products from the resin composition of the present invention can be achieved by a method commonly used for molding thermoplastic resins, such as injection molding, and the method is not limited.

〔Example〕

Hereinafter, the resin composition of the present invention will be explained using Examples and Comparative Examples.

Table 1 shows the resin composition of Examples 1 to 6, Table 2 shows the resin composition of Comparative Examples 1 to 16, Table 3 shows the resin composition of Comparative Example 17, Table 4 shows the resin composition of Examples 1 to 6, Table 5 shows the resin composition of Comparative Examples 1 to 16, and Table 6 shows the resin composition of Examples 1 to 6. The test results of Comparative Example 17 are shown.

The preparation of the resin composition and the preparation of the pieces for Test 1 were carried out in the following manner.

Preparation of resin composition Preliminary blending of each component: Performed using a drum blender.

Mixing and kneading: Ikegai Iron Works PCM twin-shaft (same direction) kneading machine (4
The mixture was kneaded and extruded using a #5 standard screw and a kneading temperature of 210°C, and pelletized using a pelletizer to obtain composition pellets.

Preparation of test piece Test piece pieces are made by injection molding. Injection molding machine Toshiba IS 100N Molding temperature 210’C Mold temperature 45°C It was made in

(Margins below) Table Comparative Example Composition (1) Crystalline ethylene propylene block copolymer Ethylene content 12wt% HFI (JISK7210 230'C2,16 Nibi f) 12g/10min (2) Hydrogenated block copolymer bond Styrene amount 30wt%) IFI (JIS K7210 230'C5Ky
f) 1'I7/10 min (3) Crystalline polyethylene density 0.966'j/cm3 HFI (JISK7210 190'C2, 16K
yf) 6g/10 minutes (4) Crystalline ethylene propylene block copolymer Ethylene content 24wt% MFI (JIS K7210 230'C2,16
Klf”) 9!7/10 minutes Crystalline propylene homopolymer HFI (7210 to JIS 230'C2,16K
yf) 8g/10 minutes Crystalline ethylene propylene random copolymer Ethylene content 3.5wt%) IFT (JISK7210 230°C2,16
KFI ()8g/10min (7) Crystalline polyethylene density 0.922'J/cm3) III (JIS K7210 190°C (8) Ethylene propylene rubber density g 0.89 g/cm3 MrI (JIS K7210 230'C ethylene Ratio 73% 2.16 Kgf) 7g/lo min 2.16 KIT) 4!7/10 min (blank below) 61F Comparative Example Composition ■ JIS K7203 ■ ■ ■ JIS K7110 ■! I ■ JIS 7301 Table 7 shows the results of the temperature dependence of the resin compositions of the present invention in Examples and Comparative Examples in terms of stress generated with temperature changes.

Examples and Comparative Examples The same stress measurement method for two people 1 to 3: 2 mm thick JIS dumbbell piece was inserted as a "rimple" Heron model 1185 was used, and the stress at 23°C was set to 0 and the stress was 140 The maximum stress that reached equilibrium when the temperature was lowered to °C.

Patent applicant: Asahi Kasei Industries, Ltd. Agent Patent Attorney Nozaki Masuya

Claims (2)

[Claims] (1) Crystalline ethylene propylene block copolymer 30
~85 parts by weight, at least one polymer block A mainly composed of a vinyl aromatic compound, and at least one polymer block B mainly composed of a hydrogenated conjugated diene compound.
20 to 60 parts by weight of a hydrogenated block copolymer consisting of
A resin composition comprising 5 to 35 parts by weight of crystalline polyethylene having a density of 0.945 g/cm^3 or more, totaling 100 parts by weight. (2) The total proportion of the crystalline ethylene propylene block copolymer and the crystalline polyethylene is 40 to 80 parts by weight, and the ratio of the crystalline ethylene propylene block copolymer to the crystalline polyethylene is 90/10 to 90/10. 50/
50. The resin composition according to claim 1, wherein the resin composition has a molecular weight of 50.