JP2854110B2 - Thermoplastic elastomer injection molding - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a thermoplastic elastomer injection molded article,
More specifically, particularly excellent dimensional stability of the molded body, molding dimensional stability at the time of molding, dimensional stability of the molded body,
The present invention relates to a thermoplastic elastomer injection-molded article such as a facer, which has an excellent balance between bending rigidity and surface smoothness (surface gloss) and is not likely to cause environmental pollution by a fibrous filler.

Technical background of the invention Thermoplastic elastomers are energy-saving and resource-saving types of vulcanized rubber substitutes, such as automobile parts (bumpers, radiator grills, air spoilers, fascias such as front panels), and industrial machine parts (pressure-resistant hoses, etc.). Gaskets), electronic and electrical equipment parts, building materials, and other applications.

By the way, conventionally, for automobile parts such as fascia,
A thermoplastic elastomer containing a fibrous filler such as glass fiber has been used. As such a thermoplastic elastomer, for example, JP-A-63-270754 discloses (a) a peroxide-crosslinked olefin-based copolymer rubber, (b) an olefin-based plastic, and (c)
An unsaturated carboxylic acid or its derivative, (d) a peroxide non-crosslinked rubbery substance, (e) a mineral oil-based softener,
Disclosed is a thermoplastic elastomer composition in which a blend containing (f) a fibrous filler is dynamically heat-treated in the presence of an organic peroxide to be partially crosslinked. JP-A-1-85206 discloses (a) a peroxide-crosslinked olefin-based copolymer rubber;
An olefin-based plastic, (c) an unsaturated epoxy monomer or an unsaturated hydroxy monomer, (d) a peroxide non-crosslinked rubbery substance, (e) a mineral oil-based softener, and (f) a fibrous material. A blend containing a filler and
Disclosed are thermoplastic elastomer compositions that are dynamically heat treated in the presence of an organic peroxide to be partially crosslinked. Further, Japanese Patent Application Laid-Open No. 61-97344 discloses a first olefin copolymer rubber partially crosslinked.
For a polymer, a second polymer composed of an ethylene / propylene block copolymer, a glass fiber, a third polymer composed of a peroxide non-crosslinked hydrocarbon rubber, and a rubber softener for a fascia. A resin composition is disclosed.

However, the thermoplastic elastomer composition as described above does not always have a balance of molding dimensional stability, dimensional stability of a molded article, bending rigidity, and surface smoothness (surface gloss) at the time of molding required as a fascia material. However, there is a problem that it is not sufficient, and the use of the fibrous filler may cause environmental pollution.

JP-A-53-149240 discloses (a) peroxide-crosslinked olefin-based copolymer rubber, (b) peroxide-decomposed olefin-based plastic, and (c) peroxide-uncrosslinked hydrocarbon-based rubber. A partially crosslinked thermoplastic elastomer composition is disclosed in which a mixture of a substance and (d) a mineral oil-based softener is dynamically heat-treated in the presence of an organic peroxide.

The present inventors have conducted intensive research to solve the above problems, and melt-kneaded an olefin resin, a specific olefin copolymer rubber, and 0 to less than 0.05 part by weight of an organic peroxide and blended. (Thermoplastic elastomer composition), and from this blend, the dimensional stability of the molded article is particularly excellent, the dimensional stability during molding, the dimensional stability of the molded article, the bending rigidity and the surface smoothness (surface Gloss)
In addition to being excellent in the balance, it is possible to obtain an injection molded article that does not cause environmental pollution by the fibrous filler,
Further, they have found that the dispersed particle size of the olefin-based copolymer rubber in the molded article is involved in the dimensional stability of the molded article, and have completed the present invention.

Object of the Invention The present invention is intended to solve the problems associated with the prior art as described above, and is particularly excellent in the dimensional stability of a molded article, the dimensional stability during molding, the dimension of the molded article. It is an object of the present invention to provide a thermoplastic elastomer injection-molded article such as a facer which has an excellent balance between stability, bending rigidity and surface smoothness (surface gloss) and is not likely to cause environmental pollution due to fibrous filler.

SUMMARY OF THE INVENTION The thermoplastic elastomer injection molded article according to the present invention comprises 90 to 10 parts by weight of an olefin-based resin (A) and 10 to 90 parts by weight of an olefin-based copolymer rubber (B) [where the components (A) and ( The total amount of the component (B) is 100 parts by weight.] Is an injection-molded product of a blend obtained by melt-kneading olefin copolymer rubber (B) in the molded product. Among them, the minor axis (ds) is 5 μm or less, and the major axis (dl) is 40 μm.
m or less, the ratio of the minor axis (ds) to the major axis (dl) (ds / dl)
It is characterized in that the dispersed particles of 0.25 or less account for 70% or more.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the thermoplastic elastomer injection molded article according to the present invention will be specifically described.

The thermoplastic elastomer molded article according to the present invention comprises an olefin resin (A) and an olefin copolymer rubber (B).
Is an injection-molded product of a blend obtained by melt-kneading.

The above-described melt-kneading is performed in the presence or absence of an organic peroxide.

Olefin Resin (A) The olefin resin (A) used in the present invention is a crystalline high molecular weight solid obtained by polymerizing one or more monoolefins by either a high-pressure method or a low-pressure method. Things. Examples of such an olefin-based resin include isotactic and syndiotactic polymer resins or copolymer resins composed of monoolefins, and representative ones thereof are commercially available.

Suitable raw olefins include, for example, ethylene,
Propylene, 1-butene, 1-pentene, 1-hexene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene, 1-octene, Examples thereof include 1-dece and a mixed olefin of two or more of these. Regarding the polymerization mode, any of a random type and a block type can be adopted as long as a resinous material can be obtained.

Among them, preferred olefin-based resins are peroxide-decomposable olefin-based plastics and polyethylene.

What is peroxide decomposable olefin plastic?
An olefin resin that is mixed with a peroxide and kneaded under heating to be thermally decomposed to reduce the molecular weight and increase the fluidity of the resin. Examples of such an olefin resin include isotactic polypropylene and propylene. And other small amount of an α-olefin, for example, a prolene-ethylene copolymer, propylene-1-
Butene copolymer, propylene-1-hexene copolymer,
A propylene-4-methyl-1-pentene copolymer and the like can be mentioned.

In the present invention, a resin obtained by modifying the olefin resin as described above with a monomer having a polar group such as an unsaturated carboxylic acid or an acid derivative thereof, an unsaturated epoxy monomer, or an unsaturated hydroxy monomer. Can be used as the olefin-based resin (A).

The melt index (ASTM-D-1238-65T, 230 ° C) of the olefin resin used in the above mixture is 0.1 to 50,
In particular, it is preferably in the range of 5 to 20. In the present invention, the olefin resin contributes to the improvement of the fluidity and the heat resistance of the composition.

In the blend according to the present invention, the olefin resin (A) is used in an amount of 90 to 1 based on 100 parts by weight of the total amount of the olefin resin (A) and the olefin copolymer rubber (B).
0 parts by weight, preferably 75 to 25 parts by weight, more preferably 6 parts by weight
It is present in an amount of 0 to 40 parts by weight.

Olefin copolymer rubber (B) In the present invention, the olefin copolymer rubber (B)
Are particles dispersed in a molded article. That is, the particles of the olefin copolymer rubber (B) are dispersed in the olefin resin (A).

Olefin copolymer rubber (B) used in the present invention
Is, for example, an ethylene-propylene copolymer rubber (EP
R), amorphous olefin-based such as ethylene-butene copolymer rubber (EBR), propylene-butene copolymer rubber (PBR), ethylene-propylene non-conjugated diene rubber, ethylene-butadiene copolymer rubber Is a relatively low molecular weight elastic copolymer. The non-conjugated diene refers to dicyclopentadiene, 1,4-hexadiene, dicyclooctadiene, methylene norbornene, ethylidene norbornene, and the like.

In the present invention, among these copolymer rubbers, ethylene-propylene copolymer rubber and ethylene-propylene non-conjugated diene rubber are preferably used, and usually, the molar ratio of ethylene unit to propylene unit (ethylene / propylene) is 40%. / 60-90 / 10 ethylene-propylene copolymer rubber, ethylene-propylene non-conjugated diene rubber is used, especially the above-mentioned molar ratio is 55 / 45-85 / 15 ethylene-
Propylene copolymer rubber and ethylene-propylene non-conjugated diene rubber are preferably used. Among them, ethylene-
Propylene non-conjugated diene copolymer rubber, especially ethylene-
Propylene-5-ethylidene-2-norbornene copolymer rubber and ethylene-propylene-5-ethylidene-
2-norbornene-dicyclopentadiene quaternary copolymer is preferred in that a thermoplastic elastomer composition having excellent heat resistance, tensile properties and rebound resilience can be obtained.

Further, the intrinsic viscosity [η] of the copolymer rubber measured in a decalin solvent at 135 ° C. is 1.0 to 3.0 dl / g, preferably 1.2 dl / g.
To 2.2 dl / g, more preferably 1.3 to 2.0 dl / g.

Further, the iodine value (unsaturation degree) of the above copolymer rubber is
It is preferably 25 or less. By using the above copolymer rubber having an iodine value in this range, a thermoplastic elastomer composition having an excellent balance between fluidity and rubber-like properties can be obtained.

In the blend of the present invention, the olefin-based copolymer rubber (B) is 10 to 90 parts by weight based on 100 parts by weight of the total amount of the olefin-based resin (A) and the olefin-based copolymer rubber (B). Preferably it is present in an amount of 25 to 75 parts by weight, more preferably 40 to 60 parts by weight.

Organic peroxide As the organic peroxide used in the present invention, specifically, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2,2 5-dimethyl-2,5-di (tert-
Butylperoxy) hexyne-3,1,3-bis (tert-
Butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-
Chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperbenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tert-butylcumyl peroxide and the like can be mentioned.

Among them, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5
-Dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5- Trimethylcyclohexane and n-butyl-4,4-bis (tert-butylperoxy) valerate are preferred, with 1,3-bis (tert-butylperoxyisopropyl) benzene being most preferred.

In the blend of the present invention, the amount of the organic peroxide is from 0 to 0.05 based on 100 parts by weight of the total amount of the olefin resin (A) and the olefin copolymer rubber (B).
It is used in an amount of less than 0 parts by weight, preferably 0 to 0.04 parts by weight, more preferably 0 to 0.03 parts by weight.

By keeping the blending amount of the organic peroxide within the above range, the crosslinking of the thermoplastic elastomer is not carried out, or by stopping the crosslinking with a small amount, the molding dimensional stability during injection molding, the dimensional stability of the molded body, the bending rigidity. In addition, a thermoplastic elastomer injection molded article having an excellent balance of surface smoothness (surface gloss) can be obtained.

In the present invention, in addition to the olefin resin (A), the olefin copolymer rubber (B) and the organic peroxide, a mineral oil softener can be included in the blend.

The mineral oil-based softening agent used in the present invention usually reduces the intermolecular force of rubber when rolling rubber, thereby facilitating the processing and dispersing carbon black, white carbon, etc. to be blended as a filler. A high-boiling petroleum fraction used for the purpose of increasing the flexibility or elasticity by reducing the hardness of the vulcanized rubber, or paraffinic,
It is classified into naphthenic, aromatic and the like.

In the present invention, the mineral oil-based softener is used in an amount of 1 to 50 parts by weight, preferably 1 to 10 parts by weight, based on the total amount of the olefin resin (A) and the olefin copolymer rubber (B). Used.

Production of Blend The blend (thermoplastic elastomer composition) constituting the thermoplastic elastomer injection molded article according to the present invention comprises 90 to 10 parts by weight of an olefin resin (A) and an olefin copolymer rubber (B). 10 to 90 parts by weight and organic peroxide 0
It is manufactured by melt-kneading the above-mentioned compound in an amount of less than 0.05 part by weight.

Examples of the kneading apparatus used in the melt kneading include an open apparatus such as a mixing roll or a non-open apparatus such as a Banbury mixer, an extruder, a kneader or a continuous mixer.

The kneading is preferably performed in a non-release type device, and is preferably performed in an atmosphere of an inert gas such as nitrogen or carbon dioxide. The temperature is usually 150-280 ° C, preferably 17
The temperature is 0 to 240 ° C, and the kneading time is usually 1 to 20 minutes, preferably 1 to 10 minutes.

In the above blend, powdery, plate-like, inorganic fillers such as fine hollow bodies, such as calcium carbonate, calcium silicate, clay, kaolin, talc, silica, diatomaceous earth, mica powder, asbestos, alumina, Barium sulfate, aluminum sulfate, calcium sulfate, basic magnesium carbonate, molybdenum disulfide, graphite, glass spheres, shirasu balloons; pigments such as carbon black, titanium oxide, zinc white, red iron oxide, ultramarine blue, navy blue, azo pigments, nitroso pigments, Lake pigments, phthalocyanine pigments; lubricants such as metal soaps and waxes; and additives such as heat stabilizers, anti-aging agents, weather stabilizers, and antistatic agents can be blended within a range that does not impair the object of the present invention.

Further, in the present invention, a small amount of a fibrous filler such as glass fiber, potassium titanate fiber and carbon fiber can be blended in the above-mentioned blend within a range where environmental pollution is not a problem.

The thermoplastic elastomer injection molded article according to the present invention is obtained by molding the thermoplastic elastomer composition obtained as described above using an injection molding machine.

The thermoplastic elastomer injection molded article according to the present invention is a thermoplastic elastomer molded article obtained as described above, and contains 70% of all dispersed particles of the olefin copolymer rubber (B) in the molded article. % Is the minor axis (ds)
5 μm or less, major axis (dl) 40 μm or less, and ratio (ds / dl) of minor axis (ds) to major axis (dl) of 0.25 or less, preferably 0.10
It has the following dispersed particle size.

70% of all dispersed particles of olefin copolymer rubber (B)
The thermoplastic elastomer injection molded article composed of the olefin-based copolymer rubber (B) having the above-described dispersed particles and the olefin-based resin (A) has particularly excellent dimensional stability.

Effects of the Invention The thermoplastic elastomer injection-molded article according to the present invention comprises an olefin resin (A) and a specific olefin copolymer rubber (B) in a specific ratio in the presence or absence of an organic peroxide. And a specific dispersed particle diameter of all the dispersed particles of the olefin copolymer rubber (B) in the molded article. 70% dispersed particles
Because it occupies the above, it is particularly excellent in the dimensional stability of the molded body,
In addition, there is an effect that the dimensional stability during molding, the dimensional stability of the molded body, the bending rigidity, and the balance of surface smoothness (surface gloss) are excellent.

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

First, the dimensional stability of the injection molded article during the molding process in the examples and comparative examples, the dimensional stability of the molded article,
The methods for evaluating the flexural rigidity, surface smoothness (surface gloss), and the dispersed particle size of the olefin copolymer rubber in the molded product are shown below.

[Evaluation method] (1) The dimensional stability during molding is evaluated by the molding shrinkage.

Molding shrinkage (%): Injection molded square plate (130mm × 120mm × 3m
Using m), the vertical and horizontal dimensions are measured, and the product shrinkage based on the mold dimensions is measured.

(2) The dimensional stability of the molded article is evaluated by the coefficient of linear expansion.

 Linear expansion coefficient: Measured according to ASTM-D-696.

Measurement temperature range: 20 to 80 ° C (deg ^-1 ) (3) Flexural rigidity is evaluated by initial flexural modulus (FM).

Initial flexural modulus (FM): Measured in accordance with ASTM-D-790.

(4) Surface smoothness (surface gloss) (i) Gloss Nippon Denshoku gloss meter (variable gloss meter VG-1D type)
The gross (60 ° specular gloss) of the injection molded article using
It is measured according to TM D 523-53T.

(Ii) PGD (Portable Distinctness of Gloss) value A portable sharpness glossiness meter (PGD-IV8) manufactured by Tokyo Koden Co., Ltd.
7442), the PGD value of the coating film of the injection-molded article coated by the following method was calculated using the following method.
Measure according to the method described on page 4.

[Coating Method] First, the surface of a square plate as an injection molded body is degreased by washing twice with 1,1,1-trichloroethane vapor for 30 seconds.

Next, a plasmar liquid consisting of 100 parts by weight of a primer [Unistor P 801 (gray) manufactured by Mitsui Petrochemical Industries, Ltd.] and 70 parts by weight of a thinner [T-SW manufactured by Nippon Bee Chemical Co., Ltd.] Apply to the square plate surface and dry at room temperature. The thickness of this coating film is 20 μm.

Further, 60 parts by weight of a urethane paint [R-271 (white) manufactured by Nippon Bee Chemical Co., Ltd.], 10 parts by weight of a curing agent [R-271 manufactured by Nippon Bee Chemical Co., Ltd.] and thinner [ After coating with 20 parts by weight of T-801] manufactured by Nippon Bee Chemical Co., Ltd., the mixture is set at room temperature for 15 minutes, and then baked at 90 ° C. for 40 minutes. The thickness of the coating film after this top coating is 35 μm.

(5) Dispersion particle size of olefin copolymer rubber Transmission electron microscope (JEM-2000F, manufactured by JEOL Ltd.)
X), the center of the molded body and the center of the thickness
Observe the dispersed particles of the olefin-based copolymer rubber at a magnification of 500 times, measure its diameter, determine the ratio between the minor axis (ds) and the major axis (dl), and determine the minor axis (ds ) Is 5 μm or less, the major axis (dl) is 40 μm or less, and 70% of the dispersed particles having the above ratio are selected. [If there are dispersed particles having the same value, these dispersed particles are also selected. (70% or more)] and the minor axis (ds) and major axis (dl) of these dispersed particles.
The average ratio of the ratio to was calculated.

Example 1 Melt flow rate (ASTM D-1238-65T, 230 ° C)
12 g / 10 min, 70 parts by weight of polypropylene having a density of 0.91 g / cm ³ (hereinafter abbreviated as PP), and an intrinsic viscosity [η] measured in a decalin solvent at 135 ° C. is 1.9 dl / g, 30 parts by weight of an ethylene / propylene copolymer rubber (hereinafter, abbreviated as rubber-1) having an ethylene content of 40 mol% was stirred and mixed by a Henschel mixer, and then heated to 220 ° C. in a nitrogen atmosphere by an extruder. Extruded thermoplastic elastomer pellets.

Next, the obtained pellets are injection-molded to obtain a molded body, and the molded body is evaluated for the molding dimensional stability, the dimensional stability of the molded body, the bending rigidity, and the surface smoothness (surface gloss) at the time of molding. It was evaluated according to the method.

The dispersed particle diameter of the olefin copolymer rubber was evaluated by cutting the molded body in the flowing direction, and dispersing particles present at the center of the molded body and at the center of the thickness according to the above evaluation method. did.

 Table 1 shows the results.

Example 2 In Example 1, the compounding amounts of PP and rubber-1 were respectively
The same procedure as in Example 1 was carried out except that 30 parts by weight and 70 parts by weight were used.

 Table 1 shows the results.

Example 3 In Example 1, instead of rubber-1, pelletized ethylene • having an intrinsic viscosity [η] of 1.4 dl / g measured in a decalin solvent at 135 ° C. and an ethylene content of 82 mol% was used. Example 1 was repeated except that a propylene / 5-ethylidene-2-norbornene copolymer rubber (hereinafter abbreviated as rubber-2) was used.

 Table 1 shows the results.

Example 4 In Example 1, PP 60 was replaced by PP 60 parts by weight.
Parts by weight and melt flow rate (ASTM D 1238-65T, 1
90 ° C) is 18 g / 10 minutes, and 20 parts by weight of low-density polyethylene (hereinafter abbreviated as PE) having a density of 0.92 g / cm ³ is used.
The same procedure as in Example 1 was carried out except that rubber -220 parts by weight was used instead of 130 parts by weight.

 Table 1 shows the results.

Comparative Example 1 In Example 1, pellet-like ethylene • having an intrinsic viscosity [η] of 5.1 dl / g measured in a decalin solvent at 135 ° C and an ethylene content of 76 mol% was used instead of rubber-1. Example 1 was repeated except that propylene / 5-ethylidene-2-norbornene copolymer rubber (hereinafter abbreviated as rubber-3) was used.

 Table 1 shows the results.

Comparative Example 2 In Example 3, in addition to PP and rubber-2, 1,3
Example 3 was repeated except that 0.1 parts by weight of bis (tert-butylperoxyisopropyl) benzene and 0.2 parts by weight of divinylbenzene were used.

 Table 1 shows the results.

Example 5 In Example 3, in addition to PP and rubber-2, except that 0.02 parts by weight of 1,3-bis (tert-butylperoxyisopropyl) benzene was used per 100 parts by weight of the total amount of these components. Performed in the same manner as in Example 3.

 Table 1 shows the results.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 23/00-23/36

Claims (3)

(57) [Claims] 1. An olefin resin (A) having 90 to 10 parts by weight,
Intrinsic viscosity [η] measured at 135 ° C in decalin solvent is 1.0 ~
10 to 90 parts by weight of the olefin copolymer rubber (B) within the range of 3.0 dl / g [however, the component (A) and the component (B)
The total amount of the components is 100 parts by weight.] Is an injection molded article of a blend obtained by kneading a solvent, and among the total dispersed particles of the olefin copolymer rubber (B) in the molded article , Minor axis (ds) 5 μm or less, major axis (dl) 40 μm
Below, the ratio (ds / dl) of the minor axis (ds) to the major axis (dl) is 0.2
A thermoplastic elastomer injection-molded article, wherein 5 or less of the dispersed particles account for 70% or more. 2. The total amount of the olefin resin (A) and the olefin copolymer rubber (B) in the blend.
A blend obtained by melt-kneading the olefin-based resin (A) and the olefin-based copolymer rubber (B) in the above ratio in the presence of an organic peroxide in an amount of less than 0.05 part by weight based on 100 parts by weight. The thermoplastic elastomer injection molded article according to claim 1, wherein: 3. The total amount of the olefin resin (A) and the olefin copolymer rubber (B) in the blend.
The thermoplastic elastomer injection-molded article according to claim 1 or 2, wherein 1 to 50 parts by weight of a mineral oil-based softener is contained based on 100 parts by weight.