KR0163984B1 - Method of manufacturing thermoplastic elastomers - Google Patents

Abstract

The present invention relates to a method for producing a thermoplastic elastomer, and more particularly, natural ethylene-vinyl acetate copolymer, sulfur-based crosslinking agent and other additives, and the like can be regenerated by dynamic crosslinking under high shear force. The present invention relates to a method for producing a thermoplastic elastomer suitable for footwear as it has excellent physical properties, slip resistance, abrasion resistance, and adhesion to a material.

Description

Manufacturing method of thermoplastic elastomer

The present invention relates to a method for producing a thermoplastic elastomer, and more particularly, to natural and synthetic rubber, to which an ethylene-vinyl acetate copolymer, a sulfur-based crosslinking agent and other additives are added, and dynamically regenerated under high shear force. The present invention relates to a method for producing a thermoplastic elastomer which is possible and has excellent physical properties, slip resistance, abrasion resistance, and adhesiveness with a material.

Conventional vulcanized rubber has excellent mechanical properties, abrasion resistance, chemical resistance, etc., but the molecular chain is covalently bonded, so the processing and molding process is very complicated and there is a problem that can not be regenerated by heat. Therefore, the demand for a new elastic body that is simple and reproducible in processing and molding to replace the conventional vulcanized rubber is increasing rapidly.

In general, the thermoplastic elastomer is bonded to the rubber phase and the resin phase by secondary physical forces such as van der Waals attraction, electrostatic attraction, and hydrogen bonding. There are possible advantages.

Therefore, conventionally, olefin-based thermoplastic elastomers for rubber replacement have been manufactured using peroxides as polypropylene resins, ethylene-propylene-diene rubbers and crosslinking agents [US Pat. No. 4,454,092]. There are many problems in applicability due to poor resistance to adhesion and adhesion with other materials.

In addition, there are copolymers using styrene, butadiene or isoprene monomers and methods using these blends (Japanese Patent 50082-162 (1973)). This has a problem of poor adhesive properties and poor wear resistance.

Accordingly, the inventors of the present invention are similar in appearance and feel to rubber, excellent resistance to slip, and excellent in tensile strength, tear strength, abrasion resistance, and heat-sealing thermoplastic elastomer to produce a thermoplastic elastomer. As a result of research efforts, the present invention has been completed by dynamically crosslinking by mixing ethylene-vinyl acetate copolymer, sulfur-based crosslinking agent and other additives with natural and synthetic rubber.

The present invention provides a method for producing a thermoplastic elastomer suitable for footwear materials having excellent physical properties such as elastic modulus, tensile strength and tear strength, low specific gravity, foaming, and excellent melt adhesive strength with artificial leather. There is a purpose.

Hereinafter, the present invention will be described in detail.

The present invention is uniformly dispersed by adding a sulfur-based crosslinking agent and other additives to a blend consisting of 10-90% by weight of rubber and 10-90% by weight of ethylene-vinyl acetate copolymer, and then in a kneading apparatus under a shear force rate of 10-100 rpm. It is characterized by dynamic crosslinking.

Referring to the present invention in more detail as follows.

The present invention relates to a method for preparing a thermoplastic elastomer in which a yellow donor crosslinking agent and other additives are added to a blend of rubber and an ethylene-vinyl acetate copolymer (hereinafter referred to as an EVA resin) and dynamically crosslinked. The rubber used in the present invention can increase the adhesion and adhesion properties to the adherend, for example, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, isoprene rubber and a mixture of two or more kinds selected from natural rubber use. In particular, butadiene rubber or styrene-butadiene rubber may cause deterioration of the molecular chain upon dynamic crosslinking with the resin, but can be prevented by using the sulfur-based crosslinking agent according to the present invention.

EVA resin exhibits various physical properties according to the graft copolymerization rate and melt flow index (hereinafter referred to as MI) of vinyl acetate, and the EVA resin used in the present invention has a graft copolymerization rate of 0.5-60 mol% of vinyl acetate, MI (190 degreeC, the load of 2.16 kg) is used for 0.5-450g / 10min. If the graft copolymerization rate of vinyl acetate is less than 0.5mol%, the flexibility, elasticity, low temperature property, impact resistance, adhesiveness and slip resistance are lowered, and when it exceeds 60mol%, the molecular weight is caused by shear force applied during dynamic crosslinking. There is a problem that the chain is cut so that mechanical properties such as tensile strength and tear strength are sharply lowered. In addition, when the MI of the EVA resin is less than 0.5g / 10 minutes, the workability of the rubber / resin blend is lowered, and when 450g / 10 minutes is exceeded, the workability is increased, but the dispersion property of the rubber is poor, and thus the mechanical properties of the thermoplastic elastomer are reduced. .

In the present invention, a blend of high density polyethylene (HDPE) and linear low density polyethylene such as 1-butene, 1-hexene or 1-octene and vinyl acetate homopolymer may also be used instead of EVA resin.

10: 90-90: 10 wt% of the rubber components listed above are blended, and when the amount of rubber used is less than 10 wt%, the behavior is similar to that of toughened plastics. .

In the present invention, 0.1-5 parts by weight of sulfur or sulfur donor is added to 100 parts by weight of the blend as a crosslinking agent in the dynamic crosslinking of the blend. Reactive materials remain to degrade the mechanical properties of the resin product, and when it exceeds 5 parts by weight, workability is reduced.

The sulfur donor may be a dithiocarbamate-based substance such as selenium dimethyldithiocarbamate, selenium diethyldithiocarbamate, or dipentamethylenethiuram tetrasulfide, tetramethylthiuram disulfide, or tetraethylthiuram disulfite. Thiuram-based materials are used. In the sulfur donor crosslinking agents listed above, the material containing the methyl group shows higher heat resistance upon dynamic crosslinking as compared to the material containing the ethyl group.

In addition, when the rubber / resin blend is dynamically crosslinked using sulfur as a crosslinking agent, an amine-based, alkyl thiocarbamate-based, benzothiazole-based, or thiuram-based material may be used in combination as a vulcanization accelerator. Alkyl thiocarbamate-based and thiuram-based vulcanization accelerators have a disadvantage in that they are unstable in the crosslinking reaction because the induction period is too short. In addition, the sulfenamide and amide vulcanization accelerator of mercaptobenzothiazole among benzothiazole-based materials have lower vulcanization promoting ability than alkyl thiocarbamate-based materials, but have a long induction period, and thus have excellent stability of vulcanization.

In addition, 0.5-10 parts by weight of ethylene glycol or a metal oxide such as zinc oxide, magnesium oxide or calcium oxide is added to 100 parts by weight of the rubber component to reduce the reaction rate and reaction time during the crosslinking reaction. Is to use.

Other additives which may be added include 100 parts by weight of the blending aid such as zinc oxide, 0.1-20 parts by weight of stearic acid, active agents such as 0.1-10 parts by weight of ethylene glycol or polyalcohol, plasticizers such as vegetable oil, 0.1-30 parts by weight of a polymer aromatic ester or EVA having a high MI, tackifiers such as 0.1-20 parts by weight of a couron indene resin or rosin ester, fillers such as carbon black, clay or silica 0.1-100 parts by weight Parts by weight may be added.

Specifically describing the method of manufacturing the thermoplastic elastomer of the present invention, first, the rubber and the resin component are added to a kneading apparatus such as a roll-mill or a kneader and kneaded at 100-120 ° C. for 2-10 minutes, and then a crosslinking agent and Add other additives and continue kneading for 2-10 minutes at the same temperature.

When uniform dispersion is achieved, the internal temperature is raised to 140-160 ° C. and dynamically crosslinked for 5-20 minutes at a shear force rate of 10-100 rpm. At this time, if the temperature inside the kneading apparatus is less than 140 ℃, the reaction time is delayed, and if it exceeds 160 ℃, physical properties are lowered due to deterioration of the rubber.

The reactants prepared by the above method are molded into various forms by extrusion or injection at a temperature range of 130-180 ° C.

The thermoplastic elastomer according to the present invention has excellent physical properties including abrasion resistance, slip resistance, and adhesive properties as compared with conventional thermoplastic elastomers, and thus can be used as a rubber substitute, and is particularly useful in manufacturing shoes.

Hereinafter, the present invention will be described in detail with reference to the following Examples, but the present invention is not limited by the Examples.

Example 1

50% by weight of styrene-butadiene rubber (SBR, Kumho Petrochemical) having a composition of styrene of 23.5 mol%, an ethylene-vinyl acetate (EVA- having a melt flow index of 6.0 g / 10 minutes and a vinyl acetate content of 28 mol%). 3) 50% by weight is added to a rubber mixer previously heated to 120 ° C. and kneaded for 3-5 minutes. 1.5 parts by weight of tetramethylthiuram disulfide (TMTD), 3.0 parts by weight of zinc oxide and 1.0 part by weight of stearic acid were added thereto, and the mixture was continuously kneaded at 120 ° C. for 3-5 minutes. When uniform dispersion of the compounding agent was made, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the dynamic speed of the screw was 60 rpm to allow 10 minutes of dynamic crosslinking to prepare a dynamic crosslinked product.

Example 2-8

By the same method as in Example 1, except that the composition of the other crosslinking agent, including the cross-linking agent as shown in Table 1 to prepare a dynamic crosslinked body.

Example 9

Ethylene-vinyl acetate with 50% by weight of butadiene rubber (BR, Kumho Petrochemical) containing 96 mol of cis-1,4-butadiene, 4.5 g / 10 min of melt flow index, and 16.5 mol% of vinyl acetate (EVA-2) 50% by weight is added to a rubber mixer preheated to 120 ° C. and kneaded for 3-5 minutes. To this was added 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester and kneading at 120 ° C. for 3-5 minutes. When uniform dispersion of the compounding agent was made, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the dynamic speed of the screw was set at 60 rpm for 10 minutes to prepare a dynamic crosslinked product.

Example 10-17

By the same method as in Example 9, but was changed to the composition of the rubber and other additives as shown in Table 1 to prepare a dynamic crosslinked body.

Example 18

50% by weight of butadiene rubber (BR, Kumho Petrochemical) having a content of cis-1,4-butadiene, ethylene-vinyl acetate having a melt flow index of 1.5g / 10 minutes and a content of vinyl acetate of 15mol% 50% by weight of EVA-1 was added to a rubber mixer preheated to 120 ° C. and kneaded for 3-5 minutes. To this was added 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester and kneading at 120 ° C. for 3-5 minutes. When uniform dispersion of the compounding agent was made, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the dynamic speed of the screw was 60 rpm to allow 10 minutes of dynamic crosslinking to prepare a dynamic crosslinked product.

Example 19-20

In the same manner as in Example 18, except that ethylene-vinyl acetate (EVA-4) having a melt flow index of 20 g / 10 min and a vinyl acetate content of 20 mol% as a plasticizer, as shown in Table 1, to provide a dynamic crosslinked product Prepared.

Example 21-22

In the same manner as in Example 18, except that dioctyl phthalate (DOP, Hanyang Chemical Co., Ltd.) was added as a plasticizer to prepare a dynamic crosslinked product as shown in Table 1 below.

Example 23

50% by weight of acrylonitrile butadiene rubber (NBR, Kumho Petrochemical) having an acrylonitrile content of 34 mol%, ethylene-vinyl acetate having a melt flow index of 4.5 g / 10 minutes and a vinyl acetate content of 16.5 mol% ( 50% by weight of EVA-2) was added to a rubber mixer preheated to 120 ° C. and kneaded for 3-5 minutes. To this, 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester are added and kneaded at 120 ° C. for 3-5 minutes. While uniformly dispersing the compounding agent, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the dynamic speed of the screw was set at 60 rpm for 10 minutes to prepare a dynamic crosslinked product.

Example 24-25

In the same manner as in Example 23, except that only the type of rubber as shown in Table 1 to prepare a dynamic crosslinked body.

Example 26

Ethylene-vinyl acetate with 50% by weight of butadiene rubber (BR, Kumho Petrochemical) containing 96 mol of cis-1,4-butadiene, 4.5 g / 10 min of melt flow index, and 16.5 mol% of vinyl acetate (EVA-2) 25% by weight and 25% by weight of low density polyethylene having a graft copolymerization rate of 32.2 mol% and a melt flow index of 2.7 g / 10 min were added to a rubber mixer preheated to 120 ° C. Knead for 3-5 minutes. To this, 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester are added and kneaded at 120 ° C. for 3-5 minutes. While uniformly dispersing the compounding agent, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the dynamic speed of the screw was set at 60 rpm for 10 minutes to prepare a dynamic crosslinked product.

Example 27

In the same manner as in Example 26, but by varying the composition of the resin as shown in Table 2 to prepare a dynamic crosslinked product.

Example 28

Ethylene-vinyl acetate with 50% by weight of butadiene rubber (BR, Kumho Petrochemical) containing 96 mol of cis-1,4-butadiene, 4.5 g / 10 min of melt flow index, and 16.5 mol% of vinyl acetate (EVA-2) 25% by weight and 25% by weight of high density polyethylene having a melt flow index of 20 g / 10 minutes are added to a rubber mixer preheated to 140 ° C. and kneaded for 3-5 minutes. To this, 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester are added and kneaded at 120 ° C. for 3-5 minutes. When uniform dispersion of the compounding agent was made, the internal temperature of the rubber mixer was fixed at 160 ° C., and then the dynamic speed of the screw was set at 60 rpm for 10 minutes to prepare a dynamic crosslinked product.

Example 29

In the same manner as in Example 28, except for the composition of the resin as shown in Table 2, a dynamic crosslinked body was prepared.

Example 30-34

In the same manner as in Example 9, but by changing the type of crosslinking agent as shown in Table 2 below to prepare a dynamic crosslinked product.

Comparative Example 1

Ethylene-vinyl acetate with 50% by weight of butadiene rubber (BR, Kumho Petrochemical) containing 96 mol of cis-1,4-butadiene, 4.5 g / 10 min of melt flow index, and 16.5 mol% of vinyl acetate (EVA-2) 50% by weight is added to a rubber mixer preheated to 120 ° C. and kneaded for 3-5 minutes. 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester are added and kneaded at 120 DEG C for 3-5 minutes. When uniform dispersion of the compounding agent was made, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the dynamic speed of the screw was set at 60 rpm for 10 minutes to prepare a dynamic crosslinked product.

Comparative Example 2

In the same manner as in Comparative Example 1, except that the crosslinking agent to 6.0 parts by weight as shown in Table 2 to prepare a dynamic crosslinked product. As a result, there was no flow characteristic during dynamic crosslinking.

Comparative Example 3

In the same manner as in Comparative Example 1, but using 20 parts by weight of ethylene glycol as shown in Table 2 to prepare a dynamic crosslinked product.

[Comparative Example 4]

Ethylene-vinyl acetate with 5% by weight of butadiene rubber (BR, Kumho Petrochemical) containing 96 mol of cis-1,4-butadiene, 4.5 g / 10 min of melt flow index, and 16.5 mol% of vinyl acetate (EVA-2) 95% by weight is added to a rubber mixer preheated to 120 ° C. and kneaded for 3-5 minutes. 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester are added and kneaded at 120 DEG C for 3-5 minutes. When uniform dispersion of the compounding agent was made, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the dynamic speed of the screw was set at 60 rpm for 10 minutes to prepare a dynamic crosslinked product.

[Comparative Example 5]

Ethylene-vinyl acetate with 95% by weight of butadiene rubber (BR, Kumho Petrochemical) having a content of cis-1,4-butadiene, and a melt flow index of 4.5g / 10 minutes and a content of vinyl acetate of 16.5mol% (EVA-2) 5% by weight is added to a rubber mixer preheated to 120 ° C. and kneaded for 3-5 minutes. To this, 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester are added and kneaded at 120 ° C. for 3-5 minutes. When uniform dispersion of the compounding agent was made, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the dynamic speed of the screw was set at 60 rpm for 10 minutes to prepare a dynamic crosslinked product. As a result, there was no flow characteristic during dynamic crosslinking.

Comparative Example 6

50% by weight of butadiene rubber (BR, Kumho Petrochemical) having a content of cis-1,4-butadiene, ethylene-vinyl acetate having a melt flow index of 450g / 10 minutes and a vinyl acetate content of 28.0mol% 50% by weight of EVA-5 was added to a rubber mixer preheated to 120 ° C. and kneaded for 3-5 minutes. To this, 3.0 parts by weight of tetramethylthiuram disulfide (TMTD), 6.0 parts by weight of zinc oxide, 1.0 part by weight of stearic acid, 2.0 parts by weight of ethylene glycol, and 3.0 parts by weight of rosin ester are added and kneaded at 120 ° C. for 3-5 minutes. After uniform dispersion of the compounding agent, the internal temperature of the rubber mixer was fixed at 150 ° C., and then the crosslinking was performed dynamically for 10 minutes at a rotation speed of 60 rpm.

(1) Ethylene-vinyl acetate copolymer having a graft copolymerization ratio of vinyl acetate of 15 mol% and a melt flow index of 1.5 g / 10 min.

(2) Ethylene-vinyl acetate copolymer having a graft copolymerization ratio of vinyl acetate of 16.5 mol% and a melt flow index of 4.5 g / 10 minutes.

(3) Ethylene-vinyl acetate copolymer having a graft copolymerization ratio of vinyl acetate of 28 mol% and a melt flow index of 6.0 g / 10 minutes.

(4) Butadiene rubber having a content of cis-1,4-butadiene at 96 mol% (Kumho Petrochemical)

(5) Styrene-butadiene rubber having a composition of styrene of 23.5 mol% (Kumho Petrochemical)

(6) Tetramethylthiuram disulfide

(7) stearic acid

(8) ethylene glycol

(9) rosin ester

(10) carbon black

(11) Ethylene-vinyl acetate copolymer having a graft copolymerization ratio of vinyl acetate of 20 mol% and a melt flow index of 20 g / 10 minutes.

(12) dioctyl phthalate

(13) Low density polyethylene having a graft copolymerization rate of 32.2 mol% and a melt flow index of 2.7 g / 10 minutes

(14) high density polyethylene with a melt flow index of 20 g / 10 min.

(15) Acrylonitrile Butadiene Rubber

(16) isoprene rubber

(17) natural rubber

(18) selenium dimethyldithio carbamate

(19) selenium diethyldithio carbamate

(20) dipentamethylenethiuram tetrasulfite

(21) tetraethylthiuram disulfide

(22) sulfur

(23) Ethylene-vinyl acetate copolymer having a graft copolymerization ratio of vinyl acetate of 28 mol% and a melt flow index of 450 g / 10 minutes.

Experimental Example

The dynamic crosslinked product prepared in Examples 1 to 34 was sheeted through a roll-mill, and the test specimen was fabricated by pressing at 150 ° C. again, and then its physical properties were specified according to ASTM. The results are shown in Table 3 below.

Experimental Example 2

In order to measure the peel strength of the thermoplastic elastomer prepared in Example 9, using a CR-based adhesive [Dongsung Chemical Products Co., Ltd.], primer 007 [Dongsung Chemical Products Co., Ltd.] pretreatment agent and using natural leather as a coating agent The test was conducted by ASTM D-903. The results are shown in Table 4 below.

Claims (3)

In the preparation of thermoplastic elastomer by mixing ethylene-vinyl acetate with rubber and adding sulfur component, 10-90% by weight of rubber has a melt flow index (190 ° C, 2.16Kg load) of 0.5-450g / 10min and the content of vinyl acetate 10-90% by weight of 0.5-60 mol% of ethylene-vinyl acetate copolymer is mixed, kneaded in a kneading apparatus consisting of a roll mill or a kneader, and added and mixed with sulfur-based crosslinking agent and other additives, and then uniformly dispersed. Method for producing a thermoplastic elastomer, characterized in that the dynamic crosslinking at a shear force rate of 10-100rpm at an internal temperature of 140-160 ℃ of the kneading apparatus. The method of claim 1, wherein the rubber is a single or mixture of two or more selected from butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, isoprene rubber, and natural rubber. The method of claim 1, wherein the sulfur-based crosslinking agent is selected from sulfur, selenium dimethyldithiocarbamate, selenium diethyldithiocarbamate, dipentamethylenethiuram tetrasulfide, tetramethylthiuram disulfite and tetraethylthiuram disulfite. Method for producing a thermoplastic elastomer, characterized in that selected.