KR101412291B1 - Polyethylene elastomer modified by vinyl aromatic hydrocarbon-conjugated diene block copolymers and method of preparing the same - Google Patents

Abstract

The present invention provides a polyethylene elastomer modified with a vinyl aromatic hydrocarbon-conjugated diene block copolymer having controlled molecular structure and content of a conjugated diene, and a method of producing the modified polyethylene elastomer, wherein the modified polyethylene elastomer has excellent mechanical properties ≪ / RTI >

Description

Polyethylene elastomers modified with vinyl aromatic hydrocarbon-conjugated diene block copolymers and methods for preparing the same are also known.

TECHNICAL FIELD The present invention relates to a polyethylene elastomer modified with a vinyl aromatic hydrocarbon-conjugated diene block copolymer and a process for producing the same. More specifically, the present invention relates to a vinyl aromatic hydrocarbon-conjugated polyene elastomer having a controlled molecular structure of vinyl diene and diene content The present invention relates to a polyethylene elastomer obtained by preparing a diene block copolymer and then grafting it on a polyethylene elastomer polymerized by metallocene, and a process for producing the same.

Polyethylene copolymers are classified into high density polyethylene and linear low density polyethylene depending on the density. Density controls the content with copolymeric monomers and traditionally uses Ziegler-Natta catalysts, which have limitations in lowering the density. Polyethylene having elastic properties, that is, a polyethylene elastic copolymer, can be produced by developing a catalyst having good reactivity with a co-monomer such as a metallocene catalyst.

Such a polyethylene elastic copolymer is used as an impact modifier of polypropylene, which is a raw material of automobile bumpers or the like, or is mainly used for shoes by crosslinking and foaming. However, due to the low melting point and mechanical properties, the use of polyethylene elastic copolymer alone is limited.

The vinyl aromatic hydrocarbon-conjugated diene block copolymer is a block copolymer obtained by polymerizing a vinyl aromatic hydrocarbon using an anion initiator and then polymerizing a conjugated diene, and is referred to as diblock copolymerization. Coupling reactions or vinyl aromatic hydrocarbons can be triblock copolymerized in one step. Typically commercialized products are styrene-butadiene-styrene block copolymers. It is mainly used for impact reinforcement, asphalt adhesive, etc. It is also used for shoes.

Vinyl aromatic hydrocarbon-conjugated diene block copolymers are limited in their use for applications requiring weatherability due to the double bonds present in the diene block. In order to overcome this problem, the double bond in the diene block was hydrogenated and commercialized as a styrene-ethylene-butylene-styrene block copolymer. However, the hydrogenation process is added, which is costly and complicated.

Therefore, it has been required to develop a technique of grafting a vinyl aromatic block to a polyethylene elastic copolymer.

Japanese Patent No. 2668384 discloses a composition obtained by reacting low-density polyethylene resin particles with a vinyl aromatic monomer and an initiator to graft polystyrene.

Korean Patent Laid-Open No. 10-2004-0024846 provides a composition obtained by co-extruding a styrene-butadiene-styrene block copolymer base and a polyethylene base using metallocene polyethylene grafted with an unsaturated carboxylic acid as a connecting material.

Although the above-mentioned research has been carried out, there is a further need for research that can more easily produce a composition for grafting a vinyl aromatic block to a polyethylene elastic copolymer.

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a vinyl aromatic hydrocarbon-conjugated diene block copolymer having a controlled molecular structure, specifically, a vinyl content and a diene content of a diene, And a method for producing the same. The present invention also provides a method for producing the same.

The above object of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention provides a modified polyethylene elastomer modified with a vinyl aromatic hydrocarbon-conjugated diene block copolymer.

The present invention also provides a process for producing a modified polyethylene elastomer, which comprises mixing a vinyl aromatic hydrocarbon-conjugated diene block copolymer, a polyethylene elastomer and an initiator, and carrying out a graft reaction to produce the modified polyethylene elastomer.

According to the present invention, a polyethylene elastomer copolymer modified with a styrene-butadiene block copolymer can provide an elastic copolymer composition having superior mechanical properties without deteriorating elasticity.

There is provided a modified polyethylene elastomer modified with a vinyl aromatic hydrocarbon-conjugated diene block copolymer to achieve the above object.

The vinyl aromatic hydrocarbon-conjugated diene block copolymer may be 5 to 40 parts by weight based on 100 parts by weight of the modified polyethylene elastomer.

When the amount of the vinyl aromatic hydrocarbon-conjugated diene block copolymer is less than 5 parts by weight based on 100 parts by weight of the modified polyethylene elastomer, the increase in mechanical properties is insignificant. When the amount exceeds 40 parts by weight, the elasticity is greatly deteriorated.

The vinyl aromatic hydrocarbon monomer is selected from the group consisting of styrene,? -Methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4- cyclohexylstyrene, 4- Vinyl-5-hexyl naphthalene, and mixtures thereof. Specifically, styrene or methyl styrene is used.

Also, the conjugated diene monomer may be at least one selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, And mixtures thereof. Specifically, 1,3-butadiene or isoprene is used.

The vinyl aromatic hydrocarbon-conjugated diene block copolymer is a vinyl aromatic hydrocarbon-conjugated diene block copolymer having a vinyl aromatic hydrocarbon content of 95 to 99.5 parts by weight based on 100 parts by weight of the vinyl aromatic hydrocarbon-conjugated diene block copolymer. If the amount of the vinyl aromatic hydrocarbon is less than 95 parts by weight based on 100 parts by weight of the vinyl aromatic hydrocarbon-conjugated diene block copolymer, the content of the conjugated diene monomer is increased to increase the cross-linking between the block copolymer and the grafting with the polyethylene elastomer If it exceeds 99.5 parts by weight, the grafting reaction is difficult due to a small amount of double bonds.

The vinyl aromatic hydrocarbon-conjugated diene block copolymer is a vinyl aromatic hydrocarbon-conjugated diene block copolymer having a number average molecular weight of 3,000 to 500,000 g / mol.

More specifically, the vinyl aromatic hydrocarbon-conjugated diene block copolymer is obtained by polymerizing a vinyl aromatic hydrocarbon with at least one monomer selected from the group consisting of styrene and methylstyrene, and the conjugated diene is at least one monomer selected from the group consisting of butadiene and isoprene Polymerized vinyl aromatic hydrocarbon-conjugated diene block copolymer.

Butadiene, which is a conjugated diene monomer, has a 1,2-vinyl structure and a cystalene 1,4-structure due to the isomer. In the present invention, in order to graft the polyethylene elastomer, the more 1,2-vinyl structure having a large number of double bonds at the terminal, the more advantageous it is. Therefore, the vinyl content can be controlled by adding a substance such as tetrahydrofuran (THF), ditetrahydrofurylpropyl (DTHFP), tetramethylethylenediamine (TMEDA).

The content of the 1,2-vinyl structure in the vinyl aromatic hydrocarbon-conjugated diene block copolymer may be 50 to 95% by weight, specifically 70 to 95% by weight in the conjugated diene content constituting the conjugated diene block have.

When the content of the 1,2-vinyl structure is less than 50% by weight of the conjugated diene constituting the conjugated diene block, the grafting is insufficient. When the content of the vinyl structure exceeds 95% by weight, There is no practicality because it must be too low.

The polyethylene elastomer may be a polyethylene elastic copolymer or a polyethylene copolymer. Specifically, the density of the polyethylene elastic copolymer may be 0.85 to 0.91 g / cm < ³ >.

The modified polyethylene elastomer according to the present invention is prepared by polymerizing and grafting a vinyl aromatic hydrocarbon-conjugated diene block copolymer, a polyethylene elastomer and an initiator.

The vinyl aromatic hydrocarbon-conjugated diene block copolymer used in the present invention can be obtained by adding a vinyl aromatic solvent and a conjugated diene to a reactor containing a hydrocarbon solvent, a vinyl content control substance, an organolithium compound, and polymerizing until the consumption rate of the monomer is 99% To prepare a block copolymer. Then, water or an alcohol is added to remove the activity of the polymer to terminate the polymerization. Then, an antioxidant is added, and the mixture is homogeneously mixed with stirring. The homogeneous block copolymer solution is stirred to remove the solvent by using steam to obtain a crumb-shaped block copolymer. Thereafter, dehydration and drying are performed to remove residual solvent and moisture.

The hydrocarbon solvent may be at least one selected from the group consisting of cyclopentane, cyclohexane, cycloheptane, benzene, naphthalene, toluene, xylene, pentane, hexane, heptane and octane.

The organic lithium compound may be at least one selected from the group consisting of n-butyl lithium, sec-butyl lithium, methyl lithium, ethyl lithium, isopropyl lithium, cyclohexyl lithium, allyl lithium, vinyl lithium, phenyl lithium, have.

The modified polyethylene elastomer of the present invention may be copolymerized with at least one monomer selected from the group consisting of propylene, butene, hexene and octene.

The prepared block copolymer and the ethylene elastic copolymer are grafted using an organic peroxide as an initiator. It is advantageous to use an initiator having a half-life of from 150 ° C to 180 ° C within 10 minutes.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Changes and modifications may fall within the scope of the appended claims.

[Example]

Manufacturing example : Preparation of Block Copolymer

2626 g of purified cyclohexane, 300 g of styrene, and 4 g of DTHFT were injected into a 6 L pressure-resistant reactor substituted with nitrogen, and then maintained at 55 ° C. N-butyllithium, an initiator, was added to the reactor to polymerize the styrene. After the polymerization temperature reached a maximum temperature, the reactor temperature was lowered to 50 캜, and then 5 g of butadiene was injected to produce a butadiene block at the end of the polymerized styrene block. After completion of butadiene polymerization, 3 g of phosphoric acid ester was added to the polymerization solution to terminate the polymerization reaction, and 0.1 g of antioxidant was added to obtain a linear styrene-butadiene block copolymer solution having a weight composition ratio of styrene and butadiene of 99.4: 0.6.

The molecular weight of the prepared block copolymer was measured using high performance gel permeation chromatography (GPC). As a result, a styrene-butadiene diblock copolymer SB-1 having a number average molecular weight of 15,800 g / mol of the block copolymer was obtained. The content of 1,2-vinyl group in SB-1 analyzed by nuclear magnetic resonance method was 75.5% by weight in the butadiene structure.

Into the 6 L pressure-resistant reactor substituted with nitrogen, 2770 g of purified cyclohexane, 330 g of styrene and 4 g of DTHFT were injected and maintained at 55 ° C. N-butyllithium, an initiator, was added to the reactor to polymerize the styrene. After the polymerization temperature reached the maximum temperature, the reactor temperature was lowered to 50 캜, and then 9 g of butadiene was injected to produce a butadiene block at the end of the polymerized styrene block. After completion of butadiene polymerization, 3 g of phosphoric acid ester was added to the polymerization solution to terminate the polymerization reaction, and 0.1 g of an antioxidant was added to obtain a linear styrene-butadiene block copolymer solution having a weight composition ratio of styrene and butadiene of 97.5: 2.5. A styrene-butadiene diblock copolymer SB-2 having a number average molecular weight of 19,800 g / mol was obtained as the block copolymer. The 1,2-vinyl group content of SB-2 as analyzed by nuclear magnetic resonance was 84.3% by weight in the butadiene structure.

The solution was poured into water at a high temperature of 95 캜 with a dispersant to remove the solvent to obtain a block copolymer in the form of a crumb, followed by vacuum dehydration and oven drying to remove residual solvent and moisture to obtain a block copolymer SB -1 and SB-2 were prepared.

The polyethylene elastic copolymer was an LC-670 product of LG Chemical Co., Ltd., having a copolymerizable monomer of octene and a density of 0.87 g / cm ³ .

Example  One

15 g of styrene-butadiene block copolymer SB-2 and 135 g of a polyethylene elastic copolymer were mixed with 0.5 g of dicumyl peroxide as an initiator at room temperature.

The temperature of the Rheodrive 16 blender of Haake Rheomix was maintained at 175 ° C.

After maintaining the rotation speed of the blender rotor at 40 rpm, the mixture was introduced to start the grafting reaction. From 4 minutes after the injection, the rotor load increased and the reaction was observed. From 8 minutes, the rotor load was maintained at 22 Nm. Nine minutes after the addition, 0.25 g of an antioxidant was added and maintained for 3 minutes to obtain a polyethylene elastomer composition modified with a styrene butadiene block copolymer.

The molecular weight of the prepared copolymer composition was measured by gel permeation chromatography (GPC). Compression molding specimens having a thickness of 2 mm, a width of 15 cm and a length of 15 cm were prepared at 160 ° C to measure tensile strength, elongation, modulus and hardness.

Tensile strength, elongation and modulus were measured according to ASTM D412.

Example  2

Styrene-butadiene block copolymer SB-2 (22.5 g) and polyethylene elastic copolymer (127.5 g) were mixed at room temperature with 1 g of initiator. Grafting was carried out in the same manner as in Example 1 and physical properties were measured.

Example  3

1 g of the initiator was mixed with 45 g of the styrene-butadiene block copolymer SB-2 and 105 g of the polyethylene elastic copolymer at room temperature. Grafting was carried out in the same manner as in Example 1 and physical properties were measured.

Example  4

Styrene-butadiene block copolymer SB-1 (22.5 g) and polyethylene elastic copolymer (127.5 g) were mixed at room temperature with 1 g of initiator. Grafting was carried out in the same manner as in Example 1 and physical properties were measured.

Comparative Example  One

22.5 g of the styrene-butadiene block copolymer SB-1 and 127.5 g of the polyethylene elastic copolymer were mixed at room temperature without initiator. Grafting was carried out in the same manner as in Example 1 and physical properties were measured.

Comparative Example  2

Properties were measured using an LC-670 product from LG Chemical, which had not undergone a modification process.

[Test Example]

Table 1 shows the results of measurement of physical properties of the above Examples and Comparative Examples.

Composition Styrene-butadiene copolymer content (%) Molecular Weight The tensile strength
(kg / cm ² ) Modulus
(kg / cm ² ) Elongation
(%) Hardness
(Shorea) Number average Weight average 100% 200% 300% Example 1 10 56,600 491,000 74.1 20.6 25.9 29.3 > 1,000 74 Example 2 15 42,200 300,000 62.3 30.6 40.9 48.3 380 80 Example 3 30 31,500 147,000 34.5 34.4 - - 170 94 Example 4 15 33,600 419,000 59.5 26.3 33.5 39.4 590 78 Comparative Example 1 15 42,700 177,000 47.9 17.5 19.4 21.4 > 1,000 73
Comparative Example 2
(LC670) 0 - - 54.2 17.9 21.2 24.6 > 1,000 71

As shown in Table 1, the polyethylene elastomer modified with the styrene-butadiene block copolymer of the present invention was obtained by mixing the styrene-butadiene block copolymer in an amount of 10-30 wt% It can be seen that tensile strength, modulus and hardness are increased without decreasing the elongation as compared with Comparative Example 1 and the polyethylene elastic copolymer itself.

Claims (17)

Modifying a polyethylene elastic copolymer comprising a copolymerizable monomer selected from the group consisting of propylene, butene, hexene, octene and mixtures thereof and having a density of 0.85 to 0.91 g / cm ³ with a vinyl aromatic hydrocarbon-conjugated diene block copolymer However,
Wherein the vinyl aromatic hydrocarbon-conjugated diene block copolymer is in a range of 10 to 30 parts by weight per 100 parts by weight of the modified polyethylene elastomer. delete The method according to claim 1,
Wherein the vinyl aromatic hydrocarbon-conjugated diene block copolymer is a mixture of 95 to 99.9 parts by weight based on 100 parts by weight of the vinyl aromatic hydrocarbon-conjugated diene block copolymer and having a number average molecular weight of 3,000 to 500,000 g / mol Polyethylene elastomers. The method according to claim 1,
Wherein said vinyl aromatic hydrocarbon-conjugated diene block copolymer has a content of 1,2-vinyl structure of from 50 to 95% by weight in terms of the content of conjugated diene constituting said conjugated diene block. The method according to claim 1,
The vinyl aromatic hydrocarbons may be selected from the group consisting of styrene,? -Methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4- (p- Hexynaphthalene, and the conjugated diene block is selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl- Diene, isoprene, 2-phenyl-1,3-butadiene, and mixtures thereof. 6. The method of claim 5,
Wherein the vinyl aromatic hydrocarbon is styrene, and the conjugated diene is 1,3-butadiene or isoprene. delete delete delete A vinyl aromatic hydrocarbon-conjugated diene block copolymer, and propylene, butene, hexene, octene, and including the selected one or more copolymerizable monomers from the group consisting of a mixture thereof, and a density of 0.85 to 0.91g / cm ³ Polyethylene elastic copolymer, and An initiator having a half-life of 150 ° C to 180 ° C within 10 minutes is mixed and subjected to a graft reaction to produce the modified polyethylene elastomer of claim 1,
Wherein the vinyl aromatic hydrocarbon-conjugated diene block copolymer is in a range of 10 to 30 parts by weight per 100 parts by weight of the modified polyethylene elastomer. 11. The method of claim 10,
Wherein the vinyl aromatic hydrocarbon-conjugated diene block copolymer is at least one selected from the group consisting of a hydrocarbon solvent, tetrahydrofuran (THF), ditetrahydrofuryl propyl (DTHFP), and tetramethylethylenediamine (TMEDA) Wherein a vinyl aromatic hydrocarbon and a conjugated diene are added to a reactor containing an organolithium compound and the polymerization is continued until the consumption rate of the monomer becomes 99% or more. 11. The method of claim 10,
Wherein the content of the 1,2-vinyl structure in the vinyl aromatic hydrocarbon-conjugated diene block copolymer is 50 to 95% by weight in the content of the conjugated diene constituting the conjugated diene block. delete 12. The method of claim 11,
Wherein the hydrocarbon solvent is at least one selected from the group consisting of cyclopentane, cyclohexane, cycloheptane, benzene, naphthalene, toluene, xylene, pentane, hexane, heptane and octane. 12. The method of claim 11,
The organic lithium compound is at least one selected from the group consisting of n-butyl lithium, sec-butyl lithium, methyl lithium, ethyl lithium, isopropyl lithium, cyclohexyl lithium, allyl lithium, vinyl lithium, phenyl lithium and benzyl lithium Wherein the modified polyolefin elastomer is a polypropylene elastomer. delete delete