JPH07103274B2 - Olefin-based thermoplastic elastomer composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an olefin-based thermoplastic elastomer composition. More specifically, the present invention relates to an olefin-based thermoplastic elastomer composition which has excellent mechanical properties and can substitute for vulcanized rubber.

<Prior Art> Thermoplastic elastomer (hereinafter referred to as "TPE") does not require a vulcanization step, and can be processed by a normal thermoplastic resin molding machine. Applications have been developed in a wide range of fields including parts and miscellaneous goods. Among them, the olefinic TPE composition is
It is known from JP-A-48-26838. But,
This composition is inferior to vulcanized rubber in terms of flexibility, tensile strength at break, elongation at break, compression set, etc. in the field of vulcanized rubber replacement, and therefore has limited applications.

In order to improve these performances, the addition of a mineral oil-based softening agent or a peroxide non-crosslinking hydrocarbon-based rubber-like substance gives flexibility, and a crosslinking aid is also used to increase the degree of crosslinking and improve the compression set. Various attempts have been made. (For example, Japanese Patent Publication No. 56-15740).

However, in these compositions, even if the degree of cross-linking is increased to improve the compression set, therefore, the flexibility decreases and the breaking strength and breaking elongation in the tensile test decrease, or the bleeding of the softening agent to the composition surface occurs. It has been difficult to obtain an olefin-based TPE composition having an excellent physical property balance.

<Problems to be Solved by the Invention> In the present situation, the problems to be solved by the present invention include olefin-based TPE, particularly low hardness (Shore A hardness of 90 or less).
The olefin-based TPE is a olefin that can substitute for vulcanized rubber due to its flexibility and mechanical properties (especially tensile breaking strength, breaking elongation, compression set) and has good blow moldability, extrusion moldability or injection moldability. To provide a system-based TPE composition.

<Means for Solving the Problems> As a result of intensive studies conducted by the present inventors to overcome the drawbacks of the above-mentioned conventional methods, an oil-extended olefin-based copolymer containing a specific mineral oil-based softening agent in advance. The inventors have found that a composition obtained by partially cross-linking a mixture of a rubber and an olefin plastic is excellent in flexibility and mechanical properties, and completed the present invention.

That is, the present invention has a Mooney viscosity of 100 ° C. (ML _{1 + 4} 100 ° C.) of 170.
Oil-extended olefin copolymer rubber (A) 40-95 obtained by adding 20-150 parts by weight of a mineral oil-based softening agent to a solution containing 400 parts by weight of an olefin-based copolymer rubber
% By weight and 5 to 60% by weight of olefinic plastic (B)
The present invention relates to an olefin-based thermoplastic elastomer composition, which is obtained by partially cross-linking a mixture consisting of

The present invention will be specifically described below.

(1) The olefin copolymer rubber used in the present invention includes, for example, ethylene-propylene copolymer rubber, ethylene-propylene-non-conjugated diene rubber, (hereinafter,
It is called "EPDM". ), Ethylene-butene-non-conjugated diene rubber, and propylene-butadiene copolymer rubber are amorphous random elastic copolymers containing olefin as a main component. Among these, ethylene-propylene-non-conjugated diene rubber is particularly preferable. Examples of the non-conjugated diene include dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylene norbornene and ethylidene norbornene, and ethylidene norbornene is particularly preferable.

EPDM will be described below as an example of the olefin-based copolymer rubber.

As a more preferable specific example, the propylene content is
An ethylene-propylene-ethylidene norbornene copolymer rubber having a content of 10 to 55% by weight, more preferably 20 to 40% by weight, and an ethylidene norbornene content of 1 to 30% by weight, and further preferably 3 to 20% by weight, and 100 ℃ Mooney viscosity (ML _{1 + 4} 100 ℃) is 170-350, preferably 170
~ 300.

When the propylene content is less than 10% by weight, flexibility is lost, and when it is more than 55% by weight, mechanical performance tends to deteriorate. If the ethylidene norbornene content is less than 1%, the mechanical properties will deteriorate, and if it exceeds 30% by weight, the injection moldability will tend to decrease. 100 ° C Mooney viscosity (ML _{1 + 4} 100
If the temperature is lower than 170, mechanical properties will be lost, and if higher than 350, the appearance of the molded article will be impaired.

However, when EPDM having a Mooney viscosity of 170 to 350 is used, the mechanical properties are large, the tensile strength at break and elongation at break are dramatically improved, and the crosslinking efficiency is increased, resulting in an improvement in compression set. EPDM manufactured by a known method can be used.

(2) Next, the mineral oil-based softening agent used in the present invention is a petroleum fraction having a high boiling point, which is blended for the purpose of improving processability and mechanical properties, such as paraffin-based, naphthene-based or aroma. Although there are group-based ones, paraffin-based ones are preferably used. When the amount of the aromatic component is large, the activity of the dye becomes strong, and the intended use for transparent products or light-colored products is limited, which is not preferable.

(3) The oil-extended olefin copolymer rubber (A) contains 20 to 150 parts by weight, preferably 30 to 120 parts by weight, of a mineral oil softener per 100 parts by weight of the olefin copolymer rubber. . If it is less than 20 parts by weight, the fluidity of the olefin-based TPE composition is lowered, and particularly the extrusion processability and the injection moldability are impaired.

On the other hand, if the amount is more than 150 parts by weight, the plasticity is remarkably increased, the processability is deteriorated, and further, the properties such as physical properties of the product are deteriorated, which is not preferable.

And the oil-extended olefinic copolymer rubber (A) at 100 ° C
Mooney viscosity (ML _{1 + 4} 100 ℃) is 30-150, preferably 40
~ 100. When it is lower than 30, mechanical properties are lost, and when it is higher than 150, molding is difficult.

By blending a large amount of mineral oil-based softeners with EPDM having a Mooney viscosity of 170-350, it is possible to satisfy both the improvement of processability by securing flexibility and the improvement of fluidity, and the improvement of mechanical properties at the same time. It is possible to obtain a different olefin-based TPE composition.

Generally, mineral oil-based softeners are used as fluidity improvers in olefin-based TPE compositions.However, according to the research conducted by the present researchers, it is related to the viscosity of EPDM when oil-extended PEDM is not used. However, if 40 parts by weight or more of a mineral oil-based softening agent is blended per 100 parts by weight of EPDM, bleeding of the softening agent will occur on the surface of the TPE composition, and the contamination and adhesion of the product will be observed, which is not preferable. However, when oil-extended EPDM, which is pre-blended with 20 to 150 parts by weight of a mineral oil-based softener per 100 parts by weight of EPDM having a Mooney viscosity of 170 to 350 at 100 ° C., is used, there is no bleeding of the softener and contamination of the product. It is possible to obtain a TPE composition which has excellent properties such as breaking strength, breaking elongation, compression set, and the like, in which no tackiness or tackiness is observed. Despite the large blending ratio of this mineral oil-based softening agent, no bleeding of the softening agent is observed. The reason for using EPDM having a high Mooney viscosity is that the upper limit of the allowable oil spread of the mineral oil-based softening agent increases. It is considered that the softening agent added in advance is uniformly dispersed in EPDM.

A known method is used as the oil extension method of EPDM. For example, using a device such as a roll or a Banbury mixer, a method of oil-extending by a method of mechanically kneading EPDM and a mineral oil-based softener, or adding a predetermined amount of mineral oil-based softener to the EPDM solution, then , A method of removing the solvent by a method such as steam stripping, and the like. Among them, the preferred oil spreading method is a method using an EPDM solution, and the EPDM solution is easier to operate when an EPDM solution obtained by polymerization is used.

(4) The olefin-based plastic (B) used in the present invention is polypropylene or a copolymer of propylene and an α-olefin having 2 or more carbon atoms. Specific examples of the α-olefin having 2 or more carbon atoms include ethylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 1-decene, 3-methyl-1-pentene, 4 -Methyl-1-pentene, 1-octane and the like.

The melt flow rate of these polymers is 0.1 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min. If the melt flow rate is smaller than 0.1 g / 10 minutes or larger than 100 g / 10 minutes, problems will occur in workability.

Further, if the amount of the olefinic plastic (B) in the olefinic TPE composition according to the present invention is less than 5% by weight, the fluidity is deteriorated and the appearance of the molded article is deteriorated. Disappear.

(5) 2,5-Dimethyl-2,5-di (t-butylperoxy) hexane, as an organic peroxide for partially crosslinking a mixture of an oil-extended olefin copolymer rubber and an olefin polymer, 2,5-Dimethyl-2,5-di (t-butylperoxy) hexyne-3,1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-di (t-butylperoxy) 3 , 5,5-Trimethylcyclohexane, 2,5
-Dimethyl-2,5-di (peroxybenzoyl) hexyne-3, dicumyl peroxide and the like. Among them, especially in terms of odor and scorch, 2,5-dimethyl-2,5-
Di (t-butylperoxy) hexane is preferred.

The amount of organic peroxide added is based on 100 parts by weight of the oil-extended olefin copolymer rubber and olefin plastic.
It can be selected in the range of 0.005 to 2.0 parts by weight, preferably 0.01 to 0.6. If it is less than 0.005 parts by weight, the effect of the crosslinking reaction is small, and if it exceeds 2.0 parts by weight, it is difficult to control the reaction and it is not economically advantageous.

(6) In producing the composition of the present invention, N, N′-m-phenylene bismaleimide, toluylene bismaleimide, as a cross-linking aid at the time of partial cross-linking formation with an organic peroxide,
Peroxide crosslinking aids such as P-quinonedioxime, nitrobenzene, diphenylguanidine, trimethylolpropane, or divinylbenzene, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate,
A polyfunctional vinyl monomer such as acrymethacrylate can be blended. By blending such a compound, a uniform and mild crosslinking reaction and a reaction occur between the olefin-based copolymer rubber and the olefin-based plastic, and it is possible to improve the mechanical properties.

The addition amount of the peroxide crosslinking aid or the polyfunctional vinyl monomer can be selected within the range of 0.01 to 4.0 parts by weight based on 100 parts by weight of the total of the oil-extended olefin copolymer rubber and the olefin plastic. It is preferably 0.05 to 2.0 parts by weight. If it is less than 0.01 parts by weight, the effect is difficult to appear, and if it exceeds 4 parts by weight, it is not economically advantageous.

(7) A specific method for producing a TPE composition by partially crosslinking a mixture of an oil-extended olefin-based copolymer rubber and an olefin-based plastic will be described below.

The oil-extended olefin-based copolymer rubber (A), the olefin-based plastic (B), the organic peroxide, and, if necessary, a crosslinking auxiliary agent and the like are mixed in a specific ratio and dynamically heat-treated.
That is, they are melted and kneaded. As the mixing and kneading device, a conventionally known non-open type Banbury mixer, a twin-screw extruder or the like is used. The kneading temperature may be 150 ° C to 300 ° C for about 1 to 30 minutes. In the production of this composition, if necessary, auxiliary materials such as an inorganic filler, an antioxidant, a weather resistance agent, an antistatic agent and a coloring pigment can be added.

As a preferred method for mixing and kneading the oil-extended olefin copolymer rubber (A), the olefin plastic (B), the organic peracid, etc., the oil-extended olefin copolymer rubber (A) and the olefin A mixture with the system plastic (B), and if necessary, a cross-linking auxiliary agent and the above-mentioned auxiliary materials are blended in a predetermined ratio, and a temperature range of 150 to 250 ° C. is sufficient using a known non-open type kneading machine such as Banbury mixer. After kneading and homogenization, this composition is thoroughly blended with an organic peroxide in a closed mixer such as a tumbler or a super mixer. Then, this blend can be obtained by dynamically heat-treating at 200 ° C to 300 ° C using a twin-screw continuous extruder capable of obtaining a strong kneading force.

The auxiliary material is at any stage of manufacturing the composition,
It is possible to mix it during processing or when using the product after processing.

The embodiments of the present invention will be specifically described below with reference to examples.

<Examples> Hereinafter, the contents of the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

The test methods used for measuring the physical properties in these examples and comparative examples are as follows.

(1) Mooney viscosity (ML _{1 + 4} 100 ° C.) (hereinafter referred to as “viscosity”): According to ASTM D-927-57T. EPDM viscosity (M
L ₁ ) was calculated by the following formula.

ML ₁ : Viscosity of EPDM ML ₂ : Viscosity of oil-extended EPDM ΔPHR: Oil extension amount per 100 parts by weight of EPDM (2) Hardness: Based on ASTM D-2240. (A type,
Instantaneous value) (3) Stress at break: Based on JIS K-6301. (JIS-
No. 3 dumbbell, pulling speed 200 mm / min) (4) Elongation at break: Same as above (5) Compression set: In accordance with JIS K-6301. (70
(° C, 22Hr, compression rate 25%) (6) Melt flow rate (MFR): in accordance with JIS K-7210. (230 ℃, 2.16kg) (7) Blow moldability: blow molding machine manufactured by Japan Steel Works. (CA
UTEX-NB3B) used. Mandrel inner diameter approx. 25 mm, blow comparison 2.0, bellows mold.

Moldability is judged by the uniformity of the wall thickness of the molded product and the surface texture.

The judgment rank is as follows.

◯: Excellent Δ: Good ×: Poor (8) Injection moldability: NISSEI RESIN FS-75N type injection molding machine was used.

Molding temperature 220 ℃, mold temperature 50 ℃, injection 10 seconds, cooling 30 seconds,
Injection pressure is the minimum filling pressure required to completely fill the mold plus 2.5 kg / cm ² , mold shape 150 mm × 90 mm × 2 mm pin gate is used.

Judgment was made with flow marks and sink marks.

The judgment rank is as follows.

About flow marks and sink marks ○: Excellent △: Only seen in a very limited area.

X: Seen over the entire surface.

(9) Extrudability: Union plastic USV type 25m
mφ extruder.

Full flight type screw, screw speed 30rp
The m, T die and the irregular die were used, and the judgment was made on the extruded skin for the T die sheet and the reproducibility of the edge portion for the irregular die. The judgment ranks are as follows.

○: Excellent △: Good ×: Poor (10) Oil bleeding property: The injection molded product was left in an oven at 70 ° C for 24 hours, and the oil bleeding on the surface of the molded product was visually judged.

The judgment rank is as follows.

○: No bleeding.

Δ: There is slight bleeding.

×: There is bleeding.

Example 1 EPDM (viscosity = 242, propylene = 28% by weight, iodine value = 1)
2) 5% by weight hexane solution, per 100 parts by weight of EPDM, a mineral oil-based softening agent (Idemitsu Kosan, Diana Process Oil PW
-380) 100 parts by weight was added, and then 200 parts by weight of oil-extended EPDM (viscosity = 53), which was desolvated by steam stripping,
After 30 parts by weight of polypropylene (MFR = 12 g / 10 min) was kneaded with a Banbury mixer at 170 to 200 ° C. for 7 minutes, a pellet master batch was prepared using an extruder.

Next, 0.3 parts by weight of 2,5 per 100 parts by weight of the masterbatch
-Dimethyl-2,5-di (t-butylperoxy) hexane (hereinafter referred to as "organic peroxide") was uniformly blended for 10 minutes using a Henschel mixer.

This blended product was subjected to dynamic heat treatment at 250 ° C. ± 10 ° C. for 70 seconds using a twin-screw kneading extruder capable of obtaining a strong kneading force, pelletized, and physical properties and moldability were evaluated.

A 2 mm thick plate obtained by injection molding was used for hardness, tensile test, and measurement of physical properties of compression set.

The evaluation results are shown in Table-1.

Example 2 EPDM (viscosity = 170, propylene = 30% by weight, iodine value = 1)
Oil-extended EPDM (viscosity = 93) obtained by adding 40 parts by weight of a mineral oil-based softening agent (PW-380) to 100 parts by weight of EPDM in 4% by weight hexane solution of 4), and then desolventizing by steam stripping. 140 parts by weight and polypropylene (MFR = 12g / 10
Min) same as Example 1 except using 20 parts by weight.

The evaluation results are shown in Table-1.

Example 3 In the production of the masterbatch in Example 1, oil-extended EP
2.5 parts by weight of N, N ′ per 230 parts by weight of DM and polypropylene
-M-Phenylene bismaleimide (hereinafter referred to as "BM") was added. Also, the same as Example 1 except that the organic peroxide was 0.3 part by weight with respect to 100 parts by weight of the masterbatch. The results are shown in Table-1.

Example 4 EPDM (viscosity = 246, propylene = 38% by weight, iodine value = 1)
Oil-extended EPDM obtained by adding 70 parts by weight of a mineral oil-based softening agent (PW-380) to 100 parts by weight of EPDM in a 6% by weight hexane solution of 0), and then desolventizing by steam stripping.
170 parts by weight (viscosity = 85) and polypropylene (MFR = 12 g /
10 minutes) A masterbatch was prepared with 25 parts by weight and 2 parts by weight of BM.

In addition, 0.3 parts organic peroxide per 100 parts by weight of the masterbatch.
Same as Example 1 except that parts by weight are used. The evaluation results are shown in Table-1.

Example 5 In the production of the masterbatch in Example 2, oil-extended EP
A masterbatch was prepared by adding 2 parts by weight of BM per 160 parts by weight of DM and polypropylene. Also, master batch
Same as Example 2 except that the organic peroxide was 0.3 part by weight per 100 parts by weight. The evaluation results are shown in Table-1.

Example 6 Same as Example 3 except that a masterbatch was prepared in Example 3 with a compounding ratio of 55 parts by weight of polypropylene (MFR = 12 g / 10 minutes) and 3 parts by weight of BM per 200 parts by weight of oil-extended EPDM. The evaluation results are shown in Table-1.

Example 7 Same as Example 3 except that a masterbatch was prepared in Example 3 with a compounding ratio of 15 parts by weight of polypropylene (MFR = 12 g / 10 minutes) and 2.5 parts by weight of BM per 200 parts by weight of oil-extended EPDM. The evaluation results are shown in Table-1.

Example 8 Same as Example 3 except that the organic peracid was changed to 0.6 part by weight. The evaluation results are shown in Table-1.

Example 9 When manufacturing a masterbatch in Example 3, calcined kaolin (Engelhard SATINTON) was used as an inorganic filler.
E SPECIAL) Same as Example 3 except that 20 parts by weight was added and BM was changed to 3 parts by weight. The evaluation results are shown in Table-1.

Example 10 In Example 9, calcined kaolin (TRAN of Engelhard Co., Ltd.
Same as Example 9 except that SLINK37) was changed to 38 parts by weight.
The evaluation results are shown in Table-1.

Example 11 Same as Example 3 except that the organic peracid was 0.08 parts by weight. The evaluation results are shown in Table-1.

Example 12 1.2 parts by weight of BM and 0.04 of organic peroxide in Example 3
Same as Example 3 except that parts by weight are used. The evaluation results are shown in Table-1.

Comparative Example 1 The same as Example 1 except that EPDM and a mineral oil-based softening agent were separately used in place of the oil-extended EPDM when the masterbatch was produced using a Banbury mixer in Example 1. Table of evaluation results
2 shows.

Comparative Example 2 The same as Example 2 except that EPDM and a mineral oil-based softening agent were separately used in place of the oil-extended EPDM when producing a masterbatch with a Banbury mixer in Example 2. Table of evaluation results
2 shows.

Comparative Example 3 EPDM (viscosity = 85, propylene = 50% by weight, iodine value = 8) and mineral oil-based softening agent were separately used at the same compounding ratio when a masterbatch was produced with a Banbury mixer in Example 2. Is the same as in Example 2. The evaluation results are shown in Table-2.

Comparative Example 4 In producing a masterbatch with a Banbury mixer in Example 2, EPDM (viscosity = 36, propylene = 20% by weight, iodine value = 15) and mineral oil-based softening agent were used separately at the same compounding ratio. Is the same as in Example 2. The evaluation results are shown in Table-2.

Comparative Example 5 The same as Example 5 except that EPDM and a mineral oil-based softening agent were separately used in place of the oil-extended EPDM when producing a masterbatch with a Banbury mixer in Example 5. Table of evaluation results
2 shows.

Comparative Example 6 EPDM (viscosity = 85, propylene = 50% by weight, iodine value = 8) and mineral oil-based softening agent were separately used at the same compounding ratio in the production of the masterbatch with the Banbury mixer in Example 5. Is the same as in Example 5. The evaluation results are shown in Table-2.

Comparative Example 7 The same as Example 6 except that EPDM and a mineral oil-based softening agent were separately used in the same blending ratio in place of the oil-extended EPDM when producing a masterbatch with a Banbury mixer in Example 6. The evaluation results are shown in Table-2.

Comparative Example 8 The same as Example 7 except that EPDM and a mineral oil-based softening agent were separately used at the same compounding ratio in place of the oil-extended EPDM when the masterbatch was manufactured with a Banbury mixer in Example 7. The evaluation results are shown in Table-2.

Comparative Example 9 The same as Example 10 except that EPDM and a mineral oil-based softening agent were separately used in the same blending ratio in place of the oil-extended EPDM when the masterbatch was produced using a Banbury mixer in Example 10. The evaluation results are shown in Table-2.

As is clear from this example, compared with the comparative example, in the low hardness region, the example shows improvement in tensile rupture strength, rupture elongation, compression set, and further improvement in workability and oil bleeding property on the surface of the molded product. Is clearly recognized.

<Effects of the Invention> The present invention improves mechanical properties such as tensile strength, elongation at break, and compression set in the low hardness region of olefin-based TPE, and further improves workability and oil bleeding on the surface of molded products. It is possible to provide an olefin-based TPE composition that has improved properties and can substitute for vulcanized rubber.

As an alternative use of the vulcanized rubber of the olefin-based TPE composition according to the present invention, a weather strip, a ceiling material, an interior sheet, a bumper molding, a side molding, an air spoiler, an air duct hose, various packings and the like are used for automobile parts. For civil engineering materials and building materials, waterproofing materials, jointing materials, window frames for construction, etc. For sports equipment, grips for golf clubs and tennis rackets. Hose tubes, gaskets, etc. for industrial parts. There are hoses and packings for home appliances.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motoo Mizumori 5-1 Anezaki Kaigan, Ichihara-shi, Chiba Sumitomo Chemical Co., Ltd. (56) Reference JP-A-61-21145 (JP, A) JP-A-SHO 60-231748 (JP, A) JP-A-57-172944 (JP, A) JP-A-57-135847 (JP, A) JP-A-63-48347 (JP, A)

Claims (5)

[Claims] 1. A Mooney viscosity at 100 ° C. (ML _{1 + 4} 100 ° C.) is 170-
Oil-extended olefin-based copolymer rubber (A) 40-95 parts by weight obtained by adding 20-150 parts by weight of mineral oil-based softening agent to a solution containing 100 parts by weight of olefin-based copolymer rubber of 350 % And an olefin-based plastic (B) in an amount of 5 to 60% by weight, which is partially crosslinked to form an olefin-based thermoplastic elastomer composition. 2. An olefin copolymer rubber is ethylene-based rubber.
The composition according to claim 1, which is a propylene-non-conjugated diene rubber. 3. A patent in which an ethylene-propylene-non-conjugated diene rubber is an ethylene-propylene-ethylidene norbornene copolymer rubber having a propylene content of 10 to 55% by weight and an ethylidene norbornene content of 1 to 30% by weight. A composition according to claim 2. 4. An oil-extended olefin-based copolymer rubber (A) of 10
The composition according to claim 1, which has a Mooney viscosity (ML _{1 + 4} 100 ° C) of 0 to 30 ° C of 30 to 150. 5. The composition according to claim 1, wherein the olefin-based plastic (B) is polypropylene or a propylene-α-olefin copolymer.