JPH04202448A - Thermoplastic rubbery composition - Google Patents

Abstract

PURPOSE:To reduce elongation and distortion strain and improve flexibility, mechanical strengths, and moldability by compounding a specific unvulcanized rubber component with a polyolefin resin and vulcanizing the resulting compsn. under mixing. CONSTITUTION:50-90 pts.wt. EPDM rubber is mixed with 50-10 pts.wt. polyoctenylene resin having a mol.wt. of 10000 or higher, a trans content of 50% or higher, a degree of crystallization of 5% or higher, an m.p. of 30 deg.C or higher, and a glass transition point of -75 to -30 deg.C to give an unvulcanized rubber component. 100 pts.wt. the component, 40-150 pts.wt. polyolefin resin (e.g. an ethylene-vinyl acetate copolymer), and 0.1-1 pt.wt. vulcanizing agent are mixed at 150-200 deg.C for vulcanization.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is easy to manufacture and control the manufacturing conditions, and the resulting composition has excellent flexibility and mechanical strength, has low elongation deformation strain, and has good color processability. The present invention relates to a thermoplastic rubber composition having excellent properties.

(Prior Art and Problems) Conventionally, thermoplastic rubber-like compositions include polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers after the name of thermoplastic elastomers. thermoplastic elastomer, 1
．． Many types have been proposed, including 2-polybutadiene thermoplastic elastomers and polyvinyl chloride thermoplastic elastomers. These thermoplastic elastomers can be molded using conventional plastic molding machines, do not require a vulcanization process, and can be reused as scrap. It has been used in many fields. However, since it does not have chemical crosslinking points,
Compared to general vulcanized rubber, stress relaxation and creep phenomena are more likely to occur, and residual strain is large when deformed.

In order to improve these defects and make it more similar to vulcanized rubber,
A dynamic vulcanization process has been developed in which the rubber component is highly crosslinked under kneading and dispersed as microparticles in a thermoplastic matrix, with the composition as a whole retaining its thermoplastic characteristics.

In particular, since the technology for dynamic vulcanization has been developed mainly for EPDM rubber and polyolefin, many technologies are known regarding dynamic vulcanization for EPDM rubber. However, in order to obtain products with stable quality using the dynamic vulcanization method, the progress of vulcanization during kneading and the dispersion speed of the vulcanized rubber components are important! (The process of lancing is important, and in order to select the appropriate composition and vulcanization conditions, a lot of trial and error is required, and there is no easy solution.

The present invention was developed as a result of intensive studies aimed at developing a thermoplastic rubber composition that is easy to manufacture and control manufacturing conditions, has excellent flexibility and mechanical properties, and has low elongation strain and good moldability. It has been reached.

(Means for Solving the Problems) That is, the present invention adds 40 parts by weight to 40 parts by weight of a polyolefin resin to 100 parts by weight of an unvulcanized rubber component consisting of 50 to 90 parts by weight of EPD-1 rubber and 50 to 10 parts by weight of polyoctenylene resin. This is a thermoplastic rubber composition obtained by blending 150 parts by weight and vulcanizing the mixture while kneading.

The EPDM rubber used in the present invention is a rubber consisting of ethylene propylene and a non-conjugated monomer, and the non-conjugated monomers include 5-ethylidene-2-norbornene, 4-hexadiene, 5-methylene-2-, norbornene, 1,6-octadiene, 5
-Methyl-1,4-hexadiene, 1,3-cyclopentadiene, 1,4-cyclohexadiene, tetrahydroindene, methyltetrahydroindene, dicyclopentanene, 5-isopropylidene-2-norbornene,
Examples include 5-vinylnorbornene. Also E P
Part of the DM rubber can be replaced by ethylene propylene rubber, so-called EPM rubber, which does not contain non-conjugated diene monomers.

The polyoctenylene resin used in the present invention must be obtained by polymerizing cyclooctene, have one double bond per eight carbon atoms, have a molecular weight of 10,000 or more, and have a trans content. It is preferable that the crystallinity is 50% or more and the crystallinity is 5% or more. The melting point of this polyoctenylene resin is usually 30°C or higher, and the glass transition point is preferably in the range of -75°C to -30°C.

7, which is the base material constituting this polyoctenylene resin.
Various methods can be used to synthesize chlorotaten. For example, chlorotaten can be obtained by trimerizing buta-7ene and then hydrogenating one of the remaining two double bonds.

The above EPDM rubber may be kneaded in advance with polyoctenylene resin using a roll, and then kneaded with the polyolefin resin using a kneading machine such as a Banbury-type kneading mixer, or alternatively, a Banbury-type kneading mixer may be used from the beginning. directly onto the polyolefin resin.
M rubber and polyoctenylene resin may be added and kneaded.

The mixing ratio of EPDM rubber and polyoctenylene resin as rubber components is preferably in the range of 50 to 10 parts by weight of polyoctenylene resin to 50 to 90 parts by weight of EPDM rubber. If the amount of polyoctenylene resin exceeds the ratio of 2, it becomes difficult to properly control the vulcanization reaction, and if the vulcanization progresses even slightly, the mechanical properties of the resulting composition, especially the tensile strength and elongation properties, will be impaired. If vulcanization is insufficient, the unvulcanized portion of the polyoctenylene resin increases, resulting in a composition that is prone to creep and has a large elongation strain. On the other hand, if the amount of polyoctenylene resin is less than 0 parts by weight, it becomes difficult to manufacture and control the manufacturing conditions. In the second case, the maximum kneading torque during dynamic vulcanization becomes high, making it difficult to obtain a composition in which the rubber component is uniformly dispersed, and the mechanical properties of the resulting final composition are impaired.

This tendency becomes particularly strong when part of the EP r)M rubber is replaced with EP~1 rubber.

Further, the polyolefin resin in the composition of the present invention is EPD
Rubber component 100 consisting of M rubber and polyoctenylene resin
It is preferable that dynamic vulcanization is carried out by blending in a range of 40 parts by weight to 150 parts by weight. If it is less than 40 parts by weight, it will be difficult to make the dispersion state of both components uniform in the pellets, and the molding processability of the final composition will be poor. On the other hand, if the amount exceeds 150 parts by weight, when stress is applied to the final composition, deformation and distortion due to creep of the polyolefin resin will occur, significantly impairing the effectiveness of the dispersed rubber gum.

The polyolefin resin used in the present invention is an ethylene/vinyl acetate copolymer or ethylene/acrylic ester copolymer resin containing 2 to 20 mol% of vinyl acetate monomer units or acrylic ester monomer units. In the latter case, it may be an ethylene/acrylic ester/maleic anhydride copolymer resin in which a portion of the acrylic ester monomer units are replaced with maleic anhydride monomer units. However, copolymers using acrylic acid or methacrylic acid instead of maleic anhydride tend to cause ionic bonding due to metal oxides such as zinc oxide present as fillers in the composition during dynamic vulcanization. This is not preferred because it tends to interfere with the dispersion of the rubber component. In addition, the vinyl acetate or acrylic acid ester monomer unit that replaces the ethylene monomer unit in the ethylene copolymer resin is 2
% to 20 mole % is necessary to give the final thermoplastic rubbery composition good moldability and recovery from deformation.

Further, these polyolefin resins may be used singly in combination with the rubber component, or two or more of them may be combined in the rubber component as an appropriate mixture. For example, two or more ethylene/vinyl acetate copolymers with different vinyl acetate contents, two or more ethylene/vinyl acetate copolymers with different acrylic ester contents,
Acrylic ester copolymer or ethylene/acrylic ester/maleic anhydride copolymer, or ethylene/vinyl acetate copolymer and ethylene/acrylic ester copolymer, ethylene/acrylic ester/maleic anhydride copolymer A combination of resins, etc. may also be used. In the case of a combination of these polyolefin resins, a thermoplastic rubber composition having good mutual compatibility and good physical properties can be obtained.

Vulcanization during kneading is carried out at 150°C to 200°C, and so-called dynamic vulcanization is performed by adding a vulcanizing agent under shear stress using a kneading mixer such as a Harry mixer.
The temperature of the vulcanization system, the rotation speed of the kneading mixer, etc. depend on the type and composition of the vulcanizing agent.

For vulcanization, resin vulcanization using a phenolic resin, sulfur vulcanization using sulfur and a vulcanization accelerator, or a combination of these vulcanization systems are suitable. Vulcanization accelerators include tetramethylthiuram disulfide, N-cyclohexyl-2-penzothiazyl sulfenamide, dibenzothiazyl cisulfite, zinc methyldithiocarhamate, zinc diethyldithiocarbamate, and combinations thereof. or suitable.

In the case of resin vulcanization using a phenolic resin, it is recommended to use 3 to 7 parts by weight per 100 parts by weight of the rubber component, and in the case of sulfur-based vulcanization using sulfur and a vulcanization accelerator, the rubber component Vulcanization may be carried out in a range of 0.1 to 1 part by weight of sulfur per 100 parts by weight. If the vulcanizing agent concentration exceeds the vulcanizing agent concentration, the vulcanization rate of the rubber component becomes too fast, making it difficult to obtain a uniformly dispersed composition.

Furthermore, various fillers such as zinc oxide, aluminum carbonate, silica, carbon black, etc. may be added as necessary. Additionally, paraffinic, naphthenic, or aromatic process oils or +iJ plasticizers may be added to improve workability. In addition, various stabilizers such as lubricants, anti-blocking agents, waxes, pigments, and UV inhibitors and antioxidants may be used.

(Effects of the Invention) The rolled plastic rubber composition produced by the present invention is easy to produce, exhibits stable physical properties, and can be easily molded by various known molding methods used in the rubber or plastic industry. It is possible to obtain a composition that is flexible and has excellent mechanical properties and small deformation strain.

(Example) Next, the present invention will be specifically explained using examples.

Example 1 Ethylene/vinyl acetate copolymer (Mitsui Polychemical Co., Ltd. product, "Ehaflexox P2505j", vinyl acetate content 25% by weight, ethylene monomer unit substitution rate 9)
80 mol %) was placed in a Banbury type kneading mixer and brought to a molten state at 1.70°C. In addition to this, E
PDM rubber (Japan Synthetic Rubber Co., Ltd. product, "No5R"
-80 parts by weight of EP21J and polyoctenylene resin (
Hüls product, "VESTENAMERV8012j, trans double bond/ance double bond ratio 80/20, melting point 54℃)
100 parts by weight of the mixture was kneaded with a roll at a weight ratio of 80/20 under rotation (rotation speed: 40 rpm).
Add to a mixer and melt and knead until homogeneous.

After reaching a uniformly molten state, 5 parts by weight of zinc oxide is uniformly dispersed under the same conditions. Once uniformly dispersed, heat-reactive phenolic resin (Nikko Sukenikukudi Co., Ltd.)
P1045J) After adding 5 parts by weight, the rotation speed of the kneading mixer was increased to about 1.00 rpm.

(Tentatively named SP-based vulcanization.) Due to the reaction heat and kneading torque friction associated with the vulcanization reaction, the temperature of the system rose to 200°C. Along with this, the kneading torque also increased to a maximum of 2.66-k
Reached gf-m. After that, as kneading continues, the torque gradually decreases and after about 8 minutes it reaches a nearly constant value of 2.5 kgf.
-It became m. The kneading torque at this time is tentatively referred to as equilibrium kneading torque.

The maximum kneading torque is a measure of the difficulty of the dynamic vulcanization process; if this value greatly exceeds 3.5 kgf-m, it will be difficult to uniformly disperse each component, and there will be large variations in the physical properties of the final composition obtained. You will be able to do it. Additionally, as the kneading torque increases, the temperature of the vulcanization system becomes too high due to torque friction, causing uneven vulcanization or an imbalance between the vulcanization speed and the dispersion speed due to crosstalk. ,
This is a major cause of non-uniformity in physical properties.

In addition, the equilibrium kneading torque is a guideline for the moldability of the final product, and this value is 3 kgf-m or less, preferably 2.5 kg.
If it is less than f-m, it means that extrusion molding or injection molding used in ordinary plastic molding can be applied without any problem.

The physical properties of the composition obtained by dynamic vulcanization were determined by taking out the composition that had reached the equilibrium cross-talk torque from the mixer and hot pressing it at 180° C. to prepare a press sheet and measuring the various physical properties. The tensile properties were measured by punching out dumbbell-shaped test pieces from press sheets with different thicknesses and using a Kukoshenoto speed of 50+nm/old n. Permanent elongation strain is determined by applying a stress so that the opening force becomes 10 Q 96 elongation as marked on the T/H type test 11, holding it in this state for 10 minutes, then removing the stress, and holding it for another 10 minutes. After standing, the length between the marked lines was determined by double-doubling. These results are shown in Table 1.
Shown below.

Example 2 In place of "Evaflex P2505J" in Example 1, ethylene/ethyl acrylate copolymer "EXRON^3100J (product of Chichi Kagaku Co., Ltd., ethyl acrylate content 10% by weight, ethylene monomer unit substitution rate) was used. Using a Banbury type kneading mixer under the same conditions as in Example 1, using 100 parts by weight of 302 mol%) and using sulfur and a vulcanization accelerator instead of rsPl and 045J as vulcanizing agents, the mixture was operated at 170°C. In other words, on top of the rubber component and polyolefin component, which were melt-mixed at 170°C in a Banbury-type kneading mixer, 5% zinc oxide was added.
parts by weight and 1 part by weight of stearic acid, and at about 40 rpm.
It was evenly dispersed at a rotation speed of . Furthermore, under the same conditions, 1 part by weight of vulcanization accelerator tetramethylthiuram disulfite (TT) and vulcanization accelerator 7zothiazole disulfide (D) were added.
M) (3.5 parts by weight was added, and finally 0.5 parts by weight of sulfur was added, and the rotation speed of the kneading mixer was increased to about 10 Orpm. (Tentative name: STT vulcanization.) After that, Examples A press sheet was prepared in the same manner as in Example 1, and its physical properties were evaluated.

The results are shown in Table 1. Although the maximum kneading torque is somewhat high, the obtained composition is flexible and exhibits good physical properties.

Example 3 In Example 1, the ratio of EPDM rubber and polyoctenylene resin in the rubber component was changed, and r JSR-EP
70 parts by weight of "21", rVEsTENAMERV801
2J was set at 30 parts by weight, the ratio of rubber component and polyolefin resin component was reduced to 66.7 parts by weight, and the vulcanization system was changed from SP vulcanization system to STT vulcanization system. After curing and vulcanization, dynamic vulcanization was performed.As shown in Table 1, a composition was obtained that was flexible and had good physical properties.

Comparative Example 1 In the compounding recipe of Example 1, EPDM rubber and polyoctenylene resin r VESTENAMERV in the rubber component
Change the ratio of l1012J, r JSR-EP21J or 95 parts by weight, rVEsTENAMERV8012J or 5
This is an example in which the parts by weight and the amount of polyoctenylene resin are significantly reduced.

As seen in Table 1, the maximum kneading torque increases, and the equilibrium cross-mixing torque also shows a considerably high value. Due to non-uniform dispersion, the physical properties of the resulting composition, especially tensile strength and elongation properties, are poor.

Comparative Example 2 In the formulation of Example 1, the ratio of EPDM rubber and polyoctenylene resin in the rubber component was changed, and rJSR-E
P21J 40 parts by weight r VESTENAMER
This is an example in which V8012J was increased to 60 parts by weight.

As shown in Table 1, in case 2, both the maximum kneading torque and the equilibrium kneading torque are low values, or a large amount of unvulcanized portion of the polyoctenylene resin remains, so the physical properties of the obtained composition are good. (do not have.

Comparative Example 3 This is an example in which the amount of the polyolefin resin component relative to the rubber component was reduced in the formulation of Example 1. .3 parts by weight.In this case, as the dynamic vulcanization progresses, the vulcanized composition is crushed, making it possible to obtain a homogeneous composition and obtain test pieces for physical property evaluation. (See Table 1) Example 4.5 Example 4 is a method in which 50% by weight of the ethylene/vinyl acetate copolymer "Evaflex P2505J" in Example 1 was replaced with ethylene/acetic acid with a high vinyl acetate content. It was replaced with a vinyl copolymer (Sumitomo Chemical Co., Ltd. product, Eno Tate R5011j, vinyl acetate content 41%, ethylene monomer unit substitution rate 185 mol%), and dynamically vulcanized with an STT vulcanizing agent as the vulcanization system. This is the result of using sulfur.

In Example 5, 50 wt. AX8060J
, acrylic ester/maleic anhydride content 1%J
This is an example of replacing it with

In each case, as shown in Table 1, a flexible composition with low elongation strain was obtained.

Examples 6 to 8 In Example 6, a part of the polyoctenylene resin rVEsTENAMERV80121, which accounts for 20% by weight of the rubber component, was used as rVESTENAMERV6213J (Hüls product, trans double bond/cis double bond ratio:
50/40, melting point 33℃), added 66.7 parts by weight of Evaflex P2505J so that the ratio of rubber component and polyolefin resin component was 60/40, and dynamically treated with SP vulcanizing agent. This is an example of vulcanization.

Example 7 added styrene to the composition obtained in Example 6.
Butadiene-styrene triblock copolymer [Califlex TR1102J (Shell Chemical Co., Ltd. product)
Add 33.3 parts by weight of and blend with a kneading mixer.
It's double.

In Example 8, in the same way as in Example 7, ethylene/vinyl acetate copolymer "Evatate R" was added to the composition obtained in Example 6.
This is an example in which 333 parts by weight of 5011J was added and blended using a kneading mixer.

These results, as shown in Table 1, provide flexible compositions with low elongation strain.

Example 9 In the formulation of Example 1, E P D Li rubber r
JSR-EP21J and its 20% by weight EPM rubber (Japan Synthetic Rubber Co., Ltd. product, rJSR-EPO2P)
J) This is an example in which dynamic vulcanization was performed using an SP-based vulcanizing agent in the same manner as in Example]. The composition is easy to manufacture;
As shown in Table 1, the resulting composition is flexible, tough,
It shows good physical properties.

Claims (1)

[Claims] 40 to 150 parts by weight of a polyolefin resin is blended with 100 parts by weight of an unvulcanized rubber component consisting of 50 to 90 parts by weight of EPDM rubber and 50 to 10 parts by weight of polyoctenylene resin, and vulcanization is performed while kneading. A thermoplastic rubbery composition obtained by