JPH1087912A - Thermoplastic polymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermoplastic polymer composition improved in environmental deterioration resistance, etc., and capable of exhibiting excellent mechanical characteristics by blending to obtain the polymer composition an olefinic polymer having specific physical properties, a propylene polymer, an oil, a radical polymerization initiator and a crossliking auxiliary in a specific ratio. SOLUTION: This thermoplastic polymer composition comprises (A) 100 pts.wt. of an olefinic polymer comprising ethylene and at least one kind of 3-10C α-olefin and having a density of 0.85-0.91g/cm<3> and a mol.wt. distribution (Mw/Mn) of <3.0 which is the ratio of the weight-average mol.wt. (Mw) to the number-average mol.wt. (Mn) and calculated by gel permeation chromatography. (B) 5-100 pts.wt. of a propylene polymer, (C) 5-250 pts.wt. of an oil, (D) 0.02-3 pts.wt. of a radical polymerization initiator, and (E) 0.1-5 pts.wt. of at least one crosslinking auxiliary selected from divinyl benzene and triallyl isocyanurate. The composition can be obtained by heating and kneading the components except the component C to partially crosslink the mixture, and subsequently adding the component C to the product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic polymer composition comprising a specific olefin polymer.

[0002]

2. Description of the Related Art Conventionally, ethylene-propylene-diene rubber (EPDM) has been generally used for thermoplastic olefin elastomer applications. The diene component in the polymer chain is necessary to improve the crosslinkability, but the diene component makes the environmental degradation resistance insufficient, and improvement in quality has been desired.

On the other hand, ethylene-propylene rubber (EPR) containing no diene component can be crosslinked with a radical initiator such as an organic peroxide or a polyfunctional unsaturated compound. However, EPDM used in conventional thermoplastic olefin elastomers as described above,
And EPR use a so-called "multi-site catalyst" of Ziegler system, so that there are many polymerization active sites, the molecular weight distribution is very wide, and a very low molecular weight component is contained in a considerable proportion. Poor balance between flexibility and mechanical strength.

In addition, Ziegler EPR or EPD
As for M, the polymer structure to be a pellet is limited, and EPR or EPDM having other structures is not available.
Is veiled, which is not preferable because it becomes complicated in handling. Further, even in the form of pellets, there is a problem of blocking caused by the ultra-low molecular weight component, which is also not preferable.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic polymer composition which is improved in environmental resistance and the like, which are problems of conventional olefin elastomers, and has excellent mechanical properties. That is.

[0006]

Means for Solving the Problems As a result of intensive studies in view of the above points, the present inventor has found that the following thermoplastic polymer compositions solve all of the above-mentioned problems, The present invention has been completed. That is, (1) the density is in the range of 0.85 to 0.91 g / cm ³ , and gel permeation chromatography (G
PC), a molecular weight distribution (Mw / M), which is a ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
ethylene and at least 1 wherein n) is less than 3.0
100 parts by weight of an olefin polymer composed of α-olefins having 3 or more carbon atoms, (2) 5 to 100 parts by weight of a propylene polymer, (3) 5 to 250 parts by weight of an oil, and (4) radical initiator 0 0.02 to 3 parts by weight (5) A thermoplastic polymer composition comprising 0.1 to 5 parts by weight of at least one crosslinking aid selected from divinylbenzene and triallyl isocyanurate, wherein an olefin polymer and a radical An initiator, a crosslinking aid and a propylene polymer are preliminarily mixed and charged into an extruder, and after the polymer, a radical initiator and a crosslinking aid have been heated and kneaded and partially crosslinked, an oil is added in the middle. And further obtained by melt-kneading and cross-linking. Hereinafter, the present invention will be described in detail.

Olefin Polymer The olefin polymer which is the main component of the thermoplastic composition of the present invention is a copolymer comprising ethylene and at least one α-olefin having 3 to 10 carbon atoms. And has a specific density and a specific molecular weight distribution.

Examples of the α-olefin having 3 to 10 carbon atoms include propylene, butene-1, pentene-1,
Hexene-1, 4-methylpentene-1, heptene-
1, octene-1, nonene-1, decene-1 and the like. In particular, a copolymer composed of ethylene and an α-olefin having 6 to 10 carbon atoms is desirable because of its excellent balance between mechanical strength and radical crosslinkability.

The olefin polymer used in the present invention can be produced using a known metallocene catalyst. The metallocene-based catalyst is composed of a cyclopentadienyl derivative of a group IV metal such as titanium and zirconium and a co-catalyst, and is not only highly active as a polymerization catalyst, but also compared with a conventional catalyst, for example, a Ziegler-based catalyst. The molecular weight distribution of the obtained polymer is narrow, the distribution of the comonomer α-olefin having 3 to 10 carbon atoms in the copolymer is uniform, and the catalyst species are uniform.

The olefin polymer used in the present invention is different from the conventional olefin polymer using a Ziegler catalyst or the like in the polymerization catalyst, and the properties of the obtained polymer are significantly different from those of the conventional olefin polymer. I have. The characteristics of the olefin-based polymer using the metallocene-based polymerization catalyst are listed as follows. Since the polymerization catalyst is super-active, the comonomer α-
The composition of the olefin can be greatly increased as compared with the conventional art, and an elastomeric polymer having high flexibility can be obtained even without a plasticizer.

2. The comonomer distribution is uniform compared to Ziegler-based polymers. 3. Compared with Ziegler-based polymers, the molecular weight distribution is extremely sharp, the amount of low molecular weight components is extremely small, the mechanical strength and workability are excellent, and the quality is high. 4. Despite the sharp molecular weight distribution, when a long-chain branch is introduced, the melt index (I10) at 190 ° C./10 kgf specified by ASTM D1238 and the melt index (I2) at 190 ° C./2.16 kgf are obtained. The ratio (I10 / I2) is large, and the processing characteristics are excellent.

5. Excellent in weather resistance. And so on.
In an olefin polymer which is a copolymer of ethylene and an α-olefin with a Ziegler catalyst, the above-mentioned melt index ratio (I10 / I2) and molecular weight distribution show a substantially linear proportional relationship, and an increase in the melt index ratio Accordingly, the molecular weight distribution also tends to increase. Molecular weight distribution is 3 ~
It is about 10.

On the other hand, in the case of an olefin polymer using a metallocene catalyst, the molecular weight distribution becomes a sharp value of less than 3.0, and the low molecular weight component is extremely small, regardless of the value of the melt index ratio. For this reason, the mechanical strength and workability of the olefin polymer constituting the thermoplastic composition of the present invention are excellent. The molecular weight distribution of these olefin polymers is calculated by GPC. The GPC apparatus and the measuring method are not particularly limited, but the present inventors used the following apparatus and measuring method.

1. Equipment Waters 150C G
PC 2. 2. One column SHOdex AT-807S 1 Tosoh TSK-GEL GMH-H6 2 3 in total Solvent 1,2,4-trichlorobenzene 4. Measurement temperature 140 ° C 5. Standard Substance Polystyrene The olefin polymer used in the present invention preferably has a density in the range of 0.85 to 0.91 g / cm ³ . By using the olefin polymer having the density of the present invention, it is possible to obtain a thermoplastic polymer composition having excellent flexibility and mechanical strength.

The melt index of the olefin polymer used in the present invention is not particularly limited.
0.01 to 100 g / 10 minutes (190 ° C., 2.16 kg
(Load) is preferably used, and more preferably 0.05 to 50 g / 10 min. The olefin polymer used in the present invention may be a mixture of a plurality of types. Workability can be improved.

Examples of olefin polymers comprising ethylene produced by a metallocene catalyst and at least one α-olefin having 3 to 10 carbon atoms include Dow Chemical's Engage, Affinity, and Exxon's Exact. It has been known. Propylene Polymer Specific examples of the propylene polymer used in the present invention include homo-isotactic polypropylene, propylene and ethylene, butene-1, pentene-1, hexene-.
And isotactic copolymers (including block and random) with other α-olefins such as 1. At least one polymer selected from these polymers is used in a composition ratio of 5 to 100 parts by weight based on 100 parts by weight of the olefin polymer. If the amount is less than 5 parts by weight, the fluidity and processability of the composition decrease, and if it exceeds 100 parts by weight, the flexibility of the composition is insufficient, which is not desirable.

Oils The oils used in the present invention include paraffinic oils,
Process oils such as naphthenic are preferred. These are olefin polymers 1 for adjusting the hardness and flexibility of the composition.
It is used in an amount of 5 to 250 parts by weight based on 00 parts by weight. If the amount is less than 5 parts by weight, flexibility and workability are insufficient. If the amount exceeds 250 parts by weight, oil bleeding becomes remarkable, which is undesirable.

In the thermoplastic polymer composition provided by the present invention, it is necessary to combine the above-described specific olefin-based polymer, propylene-based polymer, and oil in a specific composition ratio. The balance between mechanical strength, flexibility and workability is improved. The thermoplastic composition provided by the present invention requires that the composition be partially crosslinked with a radical initiator such as an organic peroxide and a crosslinking aid. Thereby, it becomes possible to further improve the wear resistance, mechanical strength, heat resistance, and the like.

Here, specific examples of the radical initiator preferably used include 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane,
1,1-bis (t-hexylperoxy) -3,3,5
-Trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-
Butylperoxy) cyclododecane, 1,1-bis (t
-Butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,
Peroxy ketals such as 4-bis (t-butylperoxy) butane and n-butyl-4,4-bis (t-butylperoxy) valerate; di-t-butyl peroxide, dicumyl peroxide, t -Butylcumyl peroxide, α, α′-bis (t-butylperoxy-m
-Isopropyl) benzene, α, α'-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane and 2,5-dimethyl-2,5 Dialkyl peroxides such as -bis (t-butylperoxy) hexine-3; acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexa Diacyl peroxides such as noyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide and m-trioyl peroxide; t-butylperoxyacetate, t
-Butylperoxyisobutyrate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate,
Di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, and cumylperoxyoctate Peroxyesters; and
Hydrogens such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide and 1,1,3,3-tetramethylbutyl peroxide Peroxides can be mentioned.

Among these compounds, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl -2,5-bis (t-butylperoxy) hexane and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3 are preferred.

These radical initiators are used in an amount of 0.02 to 3 parts by weight, preferably 0.05 to 1 part by weight, based on 100 parts by weight of the olefin polymer. If the amount is less than 0.02 parts by weight, the crosslinking is insufficient, and if it exceeds 3 parts by weight, the physical properties of the composition are not improved, which is not preferable. Further, divinylbenzene and triallyl isocyanurate are preferably used as a crosslinking assistant. These crosslinking aids may be used in combination with other crosslinking aids. Other crosslinking aids include triallyl cyanurate, diacetone diacrylamide, polyethylene glycol diacrylate,
Polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diisopropenylbenzene, P- quinone dioxime, P, P ^'- dibenzoyl quinone dioxime, phenylmaleimide, allyl methacrylate, N, N ^{'-m-phenylene} bismaleimide, diallyl phthalate, tetraallyloxyethane, can be exemplified 1,2-polybutadiene.

These crosslinking assistants are used in an amount of 0.1 to 5 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the olefin polymer.
It is used in an amount of 5 to 2 parts by weight. If the amount is less than 0.1 part by weight, crosslinking is insufficient, and if it exceeds 5 parts by weight, the physical properties of the composition are not improved, and an excessive amount of a crosslinking aid remains, which is not preferable. Further, other resins and elastomers may be added to the thermoplastic composition of the present invention to such an extent that its characteristics are not impaired. Examples include polyethylene, polybutene, styrene-butadiene block copolymers, aromatic vinyl compound-conjugated diene compound block copolymers, and hydrogenated aromatic vinyl compound-conjugated diene compound block copolymers.

Further, the thermoplastic composition of the present invention can contain an inorganic filler and a plasticizer to such an extent that its characteristics are not impaired. Examples of the inorganic filler used here include calcium carbonate, magnesium carbonate, silica, carbon black, glass fiber, titanium oxide, and clay. Also, as the plasticizer, for example,
Examples include paraffin oil, polyethylene glycol, and phthalic acid esters such as dioctyl phthalate (DOP). Further, other additives, for example, organic / inorganic pigments, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers and the like are also preferably used.

The physical properties of the thermoplastic composition of the present invention are exhibited through a specific processing step. That is, the olefin polymer, the radical initiator, and the crosslinking aid are first mixed, and the radical initiator and the crosslinking aid are attached to the surface of the olefin polymer. Next, the mixture is mixed well with the propylene-based polymer and put into a hopper of an extruder. When the polymer is heated and melted and kneaded, the oil is added in the middle after the polymer reacts with the radical initiator and the crosslinking assistant to partially crosslink. The mixture is further melt-kneaded to make the crosslinking reaction and kneading dispersion sufficient, and then the mixture is taken out of the extruder. Pellets can be obtained to obtain pellets of the thermoplastic polymer composition of the present invention.

The form of the olefin polymer or propylene polymer to be used is preferably a finely divided form such as pellets or powdery rum. For the mechanical heating and melt-kneading of the thermoplastic composition, a general method such as a single-screw extruder, a twin-screw extruder, or the like used in the production of ordinary resin compositions and elastomer compositions can be employed. is there.

However, among them, a twin-screw extruder is preferably used. The twin-screw extruder uniformly and finely disperses the olefin-based polymer and the propylene-based polymer in the presence of a radical initiator and a crosslinking aid, further causes a crosslinking reaction, and further adds oil on the way. It is more suitable for continuously producing the thermoplastic composition of the present invention. The screw configuration of the extruder is preferably of a type in which a first-stage kneading zone exists between the oil addition position and the hopper, and a second-stage kneading zone exists after the oil addition position.

It is desirable that the radical initiator and the crosslinking aid be added to the surface of the olefin polymer by adhering them. In the method of adding a radical initiator and a crosslinking auxiliary in the middle of an extruder, the crosslinking reaction does not proceed effectively, and the vaporization or consumption of a side reaction such as a decomposition reaction of a propylene-based polymer is caused by the present invention. Cannot be obtained having good physical properties.

The degree of crosslinking is defined as a measure of the crosslinkability of the composition. 0.5 g of the thermoplastic composition is refluxed in 100 ml of trichlorobenzene for 5 hours. The solution is filtered with a filter paper for quantification, the residue on the filter paper is vacuum-dried, quantified, and calculated as the ratio (%) of the weight of the residue to the weight of the olefin-based polymer in the composition. The crosslinking degree of the thermoplastic polymer composition of the present invention is desirably 30% or more. If it is less than 30%, crosslinking is insufficient, so that heat resistance such as compression set,
Physical properties such as rebound resilience decrease. The degree of crosslinking of the composition immediately before the oil is added in the middle is preferably 50% or more of the degree of crosslinking of the thermoplastic composition finally obtained after the addition of the oil. By partially cross-linking before adding oil, the radical initiator and cross-linking auxiliary are used effectively for cross-linking, and after adding oil, absorb oil and cross-linking proceeds further while holding oil. It is considered that a composition excellent in physical properties having a structure in which the cross-linking network in the olefin polymer and the state of oil absorption and dispersion are appropriately balanced is obtained.

The hardness of the thermoplastic composition provided by the present invention is 90 or less for the surface hardness A type specified by ASTM D2240. If it exceeds 90, the characteristic feature of the inherent flexibility of the composition is not exhibited. The thermoplastic composition thus obtained can be used to produce various molded articles by any molding method. Injection molding, extrusion molding, compression molding, blow molding,
Calender molding, foam molding and the like are preferably used.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In these examples and comparative examples, the test methods used for evaluating various physical properties are as follows. (1) MFR [g / 10 min] Evaluated at 230 ° C. under a load of 10 kgf according to JIS K7210. (2) As for hardness, ASTM is obtained by stacking four 2 mm thick sheets.
In accordance with D2240, evaluation was performed using an A type in an atmosphere of 23 ° C. (3) Tensile breaking strength [kgf / cm ² ] Evaluated at 23 ° C. according to JIS K6251. (4) Tensile Elongation at Break [%] Evaluated at 23 ° C. according to JIS K6251. (5) Compression set (C-Set) [%] Evaluation was performed at 70 ° C. for 22 hours according to JIS K6301. (6) Environmental degradation resistance test Using a carbon arc type sunshine weather meter (manufactured by Suga Test Instruments), a black panel temperature of 63 ° C., rainfall time of 18 minutes / irradiation time of 120 was applied according to ASTM D1499.
And the tensile strength retention [%] after continuously exposing the 2 mm thick compression molded sheet for 150 hours.

In preparing the thermoplastic compositions of Examples and Comparative Examples, the present inventors used the following. Component (a-1) Olefin-based polymer ENGAGE EG815 manufactured by Dow Chemical Company
0 Comonomer: Octene-1 Density: 0.868 g / cm ³ Mw / Mn = 2.3 ASTM D1238 Melt Index 0.5 ASTM D2240 Hardness (Type A) 75 Component (a-2) Olefin Polymer Dow Chemical Company , ENGAGE EG820
0 Comonomer: octene-1 Density: 0.870 g / cm ³ Mw / Mn = 2.4 ASTM D1238 Melt Index 5 ASTM D2240 Hardness (Type A) 75 Component (a-3) Olefin Polymer Dow Chemical Company, AFFINITY HF1
030 Comonomer: Octene-1 Density: 0.935 g / cm ³ Mw / Mn = 2.3 ASTM D1238 Melt Index 2.7 ASTM D2240 Hardness (Type A) 97 Component (b) Ethylene-propylene-diene rubber (EPD)
M) Polymerized using a Ziegler-based multi-site catalyst C3 content: 27 wt% Diene component: Ethylidene norbornene Diene content: 4 mol% ASTM D1238 Melt index 2 component (c) Propylene polymer Isotactic polypropylene manufactured by Mitsubishi Chemical Corporation Resin, Mitsubishi Polypropylene MA2 ASTM D1238 Melt Index 16 Component (d) Paraffin oil Diana Process Oil PW- manufactured by Idemitsu Kosan Co., Ltd.
380 Component (e) Radical initiator 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane Perhexa 25B (manufactured by NOF CORPORATION) Component (f-1) Crosslinking aid Divinylbenzene component (F-2) Crosslinking aid triallyl isocyanurate

[0032]

Examples 1 to 6 and Comparative Examples 1 to 5 A twin-screw extruder (40 mm) having an oil inlet at the center of the barrel was used as an extruder.
φ, L / D = 45). As the screw, a double screw having a kneading portion before and after the oil inlet was used. A predetermined amount of a radical initiator and a crosslinking assistant are added to the pellets of the olefin polymer shown in Table 1 and adhere to the pellet surfaces. Next, propylene polymer pellets are added, and after blending well, the mixture is put into a hopper of a twin-screw extruder (cylinder temperature 220 ° C.). A predetermined amount of oil is injected by a gear pump from an oil injection port at the center of the extruder. The mixture was heated, kneaded, and pelletized to obtain a composition pellet. A sheet having a thickness of 2 mm was prepared from the obtained composition by compression molding at 200 ° C., and each mechanical property and environmental degradation resistance were evaluated.

Further, as Comparative Example 5, having the same composition as that of Example 3, oil was not added from the oil injection port at the center of the extruder, but was adsorbed and absorbed on the pellets, and then the hopper was used together with other components. The results at the time of introduction were also evaluated. Table 1 shows the results.

[0034]

[Table 1]

As is clear from the results, it is clear that the thermoplastic composition provided by the present invention has excellent mechanical properties and resistance to environmental degradation. Comparative Example 1
Is higher in hardness and lower in compression set than Example 3 having a high density of the olefin-based polymer and having the same composition.
Comparative Examples 2 and 3 are compositions using EPDM, but it is clear that they are inferior in environmental degradation resistance to Examples 3 and 5 having the same composition. Comparative Example 4 was inferior in compression set and environmental degradation resistance because no crosslinking agent was used.
In Comparative Example 5, the crosslinking reaction did not proceed effectively, and the compression set, the degree of crosslinking, and the resistance to environmental degradation were low.

In Example 1, the heat-kneaded sample in the extruder was taken out of the extruder immediately before adding the oil, and the degree of crosslinking was measured. The value was 62% of the degree of crosslinking.

[0037]

According to the present invention, the thermoplastic composition of the present invention comprises
Compared with a composition using DM or the like, it has excellent physical properties such as heat resistance such as compression set and environmental degradation resistance, and its use value is extremely large. Examples of the use of the thermoplastic composition of the present invention include automobile parts, automobile interior materials, airbag covers, mechanical parts, electric parts, cables, hoses, belts, toys, sundries, daily necessities, building materials, sheets, films, and the like. It can be widely used for other applications.

Claims (5)

[Claims] (1) A density of 0.85 to 0.91 g / c
m ³ , and a molecular weight distribution (Mw / Mn), which is a ratio of a weight average molecular weight (Mw) to a number average molecular weight (Mn), calculated by gel permeation chromatography (GPC), is 3.0. Less than 100 parts by weight of an olefin-based polymer composed of ethylene and at least one α-olefin having 3 to 10 carbon atoms (2) 5 to 100 parts by weight of a propylene-based polymer (3) 5-250 parts by weight of oil Part (4) 0.02 to 3 parts by weight of a radical initiator (5) a thermoplastic polymer composition comprising 0.1 to 5 parts by weight of at least one crosslinking aid selected from divinylbenzene and triallyl isocyanurate The olefin polymer, the radical initiator, the crosslinking aid and the propylene polymer are preliminarily mixed and charged into an extruder, and the polymer and the radical initiator are mixed. And after the cross-linking aid is crosslinked partially heated and kneaded, the thermoplastic polymer composition characterized in that it is obtained by cross-linking and further melt kneading the added middle oil. 2. The thermoplastic polymer composition according to claim 1, wherein the olefin polymer comprises ethylene and an α-olefin having 6 to 10 carbon atoms. 3. The thermoplastic polymer composition according to claim 1, wherein the olefin polymer is produced using a metallocene catalyst. 4. The thermoplastic polymer composition according to claim 1, wherein the surface hardness A type specified in ASTM D2240 is 90 or less. 5. The olefin polymer according to claim 1, wherein the degree of cross-linking of the olefin polymer is at least 30% with respect to the olefin polymer used. A thermoplastic polymer composition.