KR101501836B1 - Composition for preparing Ethylene Vinyl Acetate Copolymer, Ethylene Vinyl Acetate Copolymer, and Method of manufacturing thereof - Google Patents

Abstract

More particularly, the present invention relates to an ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) having a low melt density and a low melt density, The composition according to the present invention has a melt flowability (MI) of 8 to 25 g / 10 min and a vinyl acetate (VA) content of 26 to 28 wt% Based on the ethylene vinyl acetate (EVA) of the present invention, a dialkyl peroxide type crosslinking agent, an alkyl peroxy ester type crosslinking agent or a peroxyketal type crosslinking agent having a decomposition temperature of 130 to 190 DEG C, preferably 170 to 180 DEG C, 50 to 250 ppm of a crosslinking auxiliary, 100 to 1500 ppm of a diluent, and 50 to 600 ppm of an antioxidant.

Description

TECHNICAL FIELD The present invention relates to a composition for preparing an ethylene vinyl acetate copolymer, an ethylene vinyl acetate copolymer, and a process for preparing the ethylene vinyl acetate copolymer,

More particularly, the present invention relates to an ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) having a low melt density and a low melt density, A composition for preparing a copolymer, an EVA copolymer and a process for producing the same.

EVA copolymer resins are required to have an optimal melt tension, melt flow (MI) to form stable and fine foams when used for foaming. Generally, a resin having a high vinyl acetate (hereinafter referred to as VA) content in EVA resin can obtain a foamed product having excellent stretchability, but it is difficult to obtain a product having a high melt tension or a low MI as the VA content is high. There are various methods for increasing the melt tension and lowering the MI in such high VA content EVA resin. In the case of foaming, lowering MI by crosslinking by organic peroxide rather than crosslinking by copolymerization with an electron beam crosslinking or a monomer having double bonding is a commercial . However, direct crosslinking by organic peroxide is difficult to control for MI and easy to generate gel or fish eye, making it difficult to use for film or wire.

It is an object of the present invention to provide a composition for producing a hyperbranched crosslinked EVA copolymer having a high melt tension and a low gel or fish eye production and a process for producing the same.

In order to achieve the object of the present invention, the present invention relates to an ethylene vinyl acetate (EVA) having a melt flowability (MI) of 8 to 25 g / 10 min and a content of vinyl acetate (VA) of 26 to 28% A dialkyl peroxide type cross-linking agent having a partial half-life period and a decomposition temperature of 170 to 190 ° C, an alkyl peroxy ester type cross-linking agent having a half-life half-life decomposition temperature of 130 to 180 ° C or a peroxyketal system cross- Or more of an organic peroxide, 50 to 250 ppm of a crosslinking auxiliary, 100 to 1500 ppm of a diluent, and 50 to 600 ppm of an antioxidant.

According to another aspect of the present invention, there is provided a method for preparing an ethylene vinyl acetate copolymer, comprising the steps of: preparing a composition for preparing an ethylene vinyl acetate copolymer according to the present invention; And melt kneading the composition at a temperature of 160 to 220 DEG C. The present invention also provides a method for producing an ethylene vinyl acetate copolymer.

In order to achieve still another object of the present invention, the present invention provides an ethylene vinyl acetate copolymer satisfying the following conditions (a) to (d):

(a) an MI of 1.0 to 6.0 g / 10 min,

(b) a VA content of 26 to 28% by weight,

(c) a melt tension of 190 to 1000 mN at 170 DEG C, and

(d) a molecular weight distribution (Mw / Mn) (Mw: weight average molecular weight, Mn: number average molecular weight) measured by GPC of 3.5 to 4.5.

According to the present invention, it is possible to obtain an EVA copolymer having excellent melt tension and few fish eyes by performing a minute crosslinking of a specific EVA copolymer with a crosslinking agent and a crosslinking aid. The resultant cross-linkable EVA copolymer can be used as a raw material for sole or wire for footwear.

Hereinafter, the present invention will be described in more detail.

<Composition for preparing ethylene vinyl acetate copolymer>

The composition according to an embodiment of the present invention has a melt flowability (MI) of 8 to 25 g / 10 min and an ethylene vinyl acetate (EVA) content of 26 to 28% by weight of vinyl acetate (VA) At least one organic peroxide selected from a dialkyl peroxide type crosslinking agent, an alkyl peroxy ester type crosslinking agent or a peroxyketal system crosslinking agent having a decomposition temperature of 130 to 190 DEG C, preferably 170 to 180 DEG C, 50 to 250 ppm of a crosslinking auxiliary, 100 to 1500 ppm of a diluent, and 50 to 600 ppm of an antioxidant.

The EVA according to the present invention preferably has an MI before crosslinking of 8 to 25 g / 10 min. This is because when the MI of the EVA before crosslinking is less than RJ 8 g / 10 min or when it is crosslinked more than 25 g / 10 min, it is difficult to effectively improve the melt tension.

The organic peroxide used as the crosslinking agent according to the present invention has a one-minute half-life decomposition temperature of 130 to 190 ° C, preferably 170 to 180 ° C. When the decomposition temperature for obtaining a half-life period of 1 minute is less than 130 ° C, long-term storage is difficult and the crosslinking reaction is initiated before the organic peroxide is dispersed, and gel is liable to occur. When the temperature exceeds 190 ° C, Cetal acetic acid occurs or cutting becomes difficult during pelletization.

The organic peroxide used as the crosslinking agent according to the present invention is preferably added in an amount of 50 to 500 ppm based on EVA. When the addition amount is less than 50 ppm, crosslinking is insufficient and a desired melt viscosity can not be obtained. When the addition amount is more than 500 ppm, gel or fish eye is increased or crosslinked to a desired level or more.

Specific examples of the dialkyl peroxide crosslinking agent according to the present invention include 2,4-dimethyl-2,5-bis (t-butylperoxy) hexane (2,5- butylperoxy-hexane). Specific examples of the alkyl peroxy ester cross-linking agent include tert-butylperoxy-2-ethylhexyl carbonate and the like. Examples of the peroxyketal- 1,1-di- (t-butylperoxy) -3,3,5-trimethylcyclohexane, and the like.

The crosslinking aid used in the present invention is a polymerizable multifunctional monomer having at least two double bonds and having at least two double bonds in order to suppress generation of bubbles at the time of crosslinking and thereafter increase the crosslinking rate to give excellent productivity and good appearance. A compound or a methacrylate compound may be used. The addition amount of the EVA is preferably 50 to 250 ppm. When it is added in an amount of less than 50 ppm, the effect of increasing the crosslinking rate is insignificant, and when it is added in an amount of more than 250 ppm, the amount of gel or fish eye is increased or crosslinked to a desired level or more.

Specific examples of the crosslinking auxiliary include triallyl isocyanurate, triallyl cyanurate, 1,4-butanedioldimethacrylate, trimethylolpropane trimethacrylate, Trimethylol propane trimethacrylate, triethyleneglycol dimethacrylate, and the like.

The diluent according to the present invention is added to improve workability and homogenize the cross-linking in the kneading process, and it can be used in high boiling point process oil or odorless mineral spirits (white sprits) And the addition amount is 100 to 1500 ppm. When the addition amount exceeds 1500 ppm, the crosslinking efficiency deteriorates. When the addition amount is less than 100 ppm, it is difficult to uniformly disperse the organic peroxide.

As the antioxidant according to the present invention, a phenol-based antioxidant and a phosphorus-based antioxidant are used. Examples of the phenol-based antioxidant include monophenol-based, thio-bisphenol-based, and trisphenol-based antioxidants, Octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tetrakis [methylene Methyl-3- (3 ', 5'-di-tert-butyl-4', 5'-di- -hydroxyphenyl) propionate] methane}, Tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate {Tris ) isocyanurate}, and examples of the phosphorus antioxidant include tris (2,4-di-tert-butylphenyl) phosphate, tris (nonylphenyl) phosphate [ Tris (nonylphenyl) phosphate], and the like, Or mixture can be used as a.

The amount of the antioxidant to be added is 50 to 600 ppm with respect to the EVA resin. When the addition amount exceeds 600 ppm, the product is bleed to the surface of the product to deteriorate the appearance of the product. When the amount is less than 50 ppm, the effect as an antioxidant is insufficient, It is difficult to control the MI, so a stable quality product can not be obtained.

The composition for preparing an EVA copolymer according to the present invention may contain, if necessary, an ethylene-ethyl acrylate (EEA) copolymer, an ethylene methyl methacrylate copolymer, an ethylene propylene rubber (EPR), an ethylene propylene diene copolymer EPDM and ethylene butene copolymers; polyolefin resins such as polypropylene and polyethylene; fillers such as talc, calcium carbonate, clay, mica, barium sulfate, magnesium hydroxide and aluminum hydroxide; lubricants, pigments, Weathering stabilizers, antiblocking agents, various stabilizers, plasticizers, oils, foaming agents, flame retardants and the like.

<Ethylene Vinyl Acetate Copolymer and Method for Producing the Same>

The ethylene vinyl acetate copolymer according to the present invention may be prepared by simultaneously mixing the ethylene vinyl acetate copolymer composition and melt-kneading the copolymer at 160 to 220 ° C.

The temperature of the extruder cylinder to be melted and kneaded is preferably from 160 to 220 ° C. When the temperature is lower than 160 ° C., the crosslinking reaction is insufficient and the desired melt tension is not obtained. If the temperature is higher than 220 ° C., deacetic acid occurs during melt- It gets harder.

A kneader, a Banbury mixer, a single-screw extruder, and a twin-screw extruder may be used as the processing apparatus used in the present invention, but a twin-screw extruder is preferred for increasing the degree of kneading. When a specific example is given, dry EVA polymer, organic peroxide, crosslinking aid, antioxidant and diluent are dry-blended and then put into a twin-screw extruder hopper. After the EVA polymer is sufficiently dispersed before the organic peroxide decomposes, a crosslinking reaction takes place The extrusion conditions are set so that the pelletization is attained when the crosslinking reaction is completed.

The ethylene vinyl acetate copolymer produced according to the present invention satisfies the following conditions (a) to (d):

(a) an MI of 1.0 to 6.0 g / 10 min,

(b) a VA content of 26 to 28% by weight,

(c) a melt tension of 190 to 1000 mN at 170 DEG C, and

(d) a molecular weight distribution (Mw / Mn) (Mw: weight average molecular weight, Mn: number average molecular weight) measured by GPC of 3.5 to 4.5.

In the present invention, the melt tension was measured by pulling out a strand obtained by extruding EVA resin melted at 170 캜 at a cylinder diameter of 15 mm and a die L / D 32/2 piston speed of 10 mm / min at a pull off acceleration of 1 mm / sec ² Value.

Hereinafter, the present invention will be described in more detail by way of the following examples, but the scope of the present invention is not limited to these examples.

Various tests were carried out in the following manner and the performance was evaluated.

1) Acetic acid odor

Five persons were evaluated for the EVA pellet with a very small amount of cross-linking, and when two or more persons experienced severe acetic acid odor, it was judged to be defective.

2) Fish Eye

The ultrafine crosslinked EVA pellets were subjected to T-die casting at 160 DEG C through a single-screw extruder to prepare a sheet having a thickness of 400 mu m, and then a fish eye having a size of 0.5 mm or more was visually observed.

3) Flatness of the sheet

The ultrafine crosslinked EVA pellets were subjected to T-die casting at 160 DEG C through a single-screw extruder and the surface of the sheet made to a thickness of 400 mu m was visually measured.

4) Overall evaluation

When the melt tension was 190 mN or less, and one of the smell of acetic acid, fish eye, and sheet was defective, it was evaluated as defective.

Example One

(2-ethylhexyl) monoperoxycarbonate (Luperox TBEC) as a crosslinking agent was added to an EVA copolymer (manufactured by Samsung Total Co., Ltd., containing 500 ppm of Irganox 1076) containing MI = 8 g / 10 min and VA = 26% , 115 ppm of triallyl isocyanurate (TAICROS, manufactured by Evonik) and 700 ppm of white mineral oil (Palamium KL-500, manufactured by Sejing Chemical Co., Ltd.) as a crosslinking aid were blended at room temperature for 10 minutes, The results are shown in Table 2. The results are shown in Table 2. The results are shown in Table 2. [Table 2] &lt; tb &gt;&lt; TABLE &gt;

Example 2

(2-ethylhexyl) monoperoxycarbonate (Luperox) as a crosslinking agent was added to an EVA copolymer (manufactured by Samsung Total Co., Ltd.) containing EVA as MI = 15 g / 10 min and VA = 28 weight% TBEC, manufactured by Arkema Co.), 115 ppm of triallyl isocyanurate (TAICROS, manufactured by Evonik) and 700 ppm of white mineral oil (Palamium KL-500, manufactured by Sejing Chemical Co., Ltd.) as a crosslinking aid were blended at room temperature for 10 minutes, At 200 DEG C and a screw speed of 50 rpm to evaluate the performance of the obtained EVA copolymer composition. The results are shown in Table 2. &lt; tb &gt;&lt; TABLE &gt;

Example  3

The results of evaluating the performance of the ultrafine crosslinkable EVA copolymer composition by the same mixing ratio and extrusion method as in Example 1 except that 700 ppm of branched paraffin (IP1620, manufactured by Idemitsu Co., Ltd.) was used instead of white mineral oil as a diluent The results are shown in Table 2.

Comparative Example  One

Table 2 shows the results of evaluating the performance of the EVA copolymer composition prepared by the kind of additives, the blend ratio, and the extrusion method in the same manner as in Example 1, except that the crosslinking auxiliary agent was not used.

Comparative Example  2

Except that 600 ppm of t-butyl- (2-ethylhexyl) monoperoxycarbonate (Luperox TBEC, manufactured by Arkema) was used as a crosslinking agent in the same manner as in Example 1, by the additive type, the blending ratio and the extrusion method The evaluation results of the EVA copolymer composition are shown in Table 2. &lt; tb &gt;&lt; TABLE &gt;

Comparative Example  3

Except that 230 ppm of di-t-butyl peroxide (Luperox DI, manufactured by Arkema) was used as a crosslinking agent, the performance of the EVA copolymer composition obtained by the additive type, blend ratio and extrusion method in the same manner as in Example 1 The evaluation results are shown in Table 2.

Comparative Example  4

Table 2 shows the results of evaluating the performance of the EVA copolymer composition prepared by the kind of additives, the mixing ratio, and the extrusion method in the same manner as in Example 1, except that a diluent was not used.

Comparative Example  5

Table 2 shows the results of evaluating the performance of the EVA copolymer composition prepared by the kind of additives, the blend ratio, and the extrusion method in the same manner as in Example 2, except that no antioxidant was used.

Comparative Example  6

Table 2 shows the results of evaluating the performance of the EVA copolymer composition prepared by the kind of additives, the blending ratio, and the extrusion method in the same manner as in Example 1, except that the extruder barrel temperature was 160 캜.

Comparative Example  7

Table 2 shows the results of evaluating the performance of the EVA copolymer composition prepared by the kind of additives, the blending ratio, and the extrusion method in the same manner as in Example 1, except that the extruder barrel temperature was 230 캜.

Example Comparative Example One 2 3 One 2 3 4 5 6 7 EVA ^{1 )} VA content 26%, MI 8g / 10min ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ VA content 28%, MI 15g / 10min ◎ ◎ Luperox TBEC ^{2 )} (ppm) 230 230 230 230 600 230 230 230 230 Luperox DI ^{3 )} (ppm) 230 Taicros ^{4 )} (ppm) 115 115 115 Paramium KL500 ^{5 )} (ppm) 700 700 700 700 700 700 700 700 OMS ^{6 )} (ppm) 700 Irganox 1076 ⁷⁾ (ppm) 500 500 500 500 500 500 500 500 500 Extruder temperature (캜) 200 200 200 200 200 200 200 200 160 230

1) EVA copolymer used Samsung Total product.

2) Luperox TBEC: t-Butyl- (2-ethylhexyl) monoperoxycarbonate (Arkema)

3) Luperox DI: Di-t-butyl peroxide (manufactured by Arkema)

4) Taicros: Triallyl isocyanurate (Evonik)

5) PARAMIUM KL-500: White mineral oil (manufactured by Seojin Chemical Co., Ltd.)

6) OMS: isoparaffin action with odorless mineral spirits (IP1620, manufactured by Idemitsu)

7) Irganox 1076: Octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate

Example Comparative Example One 2 3 One 2 3 4 5 6 7 VA content (%) 26 28 26 26 26 26 26 28 26 26 MI (g / 10 min.) 3.1 3.4 3.2 3.8 0.5 6.2 3.1 0.6 6.4 3.1 Melt tension (mN) 210 192 200 170 320 50 200 350 85 201 MWD 4.55 4.45 4.43 4.32 4.56 4.01 4.40 4.59 4.07 4.39 Acetic acid odor Good Good Good Good Good Good Good Good Good Bad Fish eye (pieces / m ² ) 1500 1700 2100 1500 4500 500 5000 or more Not measurable 1200 4400 Sheet smoothness Good Good Good Good Bad Good Bad Bad Good Good Overall assessment Good Good Good Bad Bad Bad Bad Bad Bad Bad

As shown in the results of Table 2, in the process according to the present invention, a specific crosslinking agent and a crosslinking aid are cross-linked to a specific EVA copolymer to obtain a low MI, a low melt tension and a low gel or fish eye , I.e., a fish eye having a size of 0.5 mm or more in a 400 mu m sheet is less than 3000 per square meter It is possible to obtain an EVA copolymer for foaming.

Claims (11)

(EVA) having a melt flowability (MI) of 8 to 25 g / 10 min and a content of vinyl acetate (VA) of 26 to 28% by weight,
50 to 500 ppm of t-butyl-2-ethylhexyl monoperoxycarbonate as a crosslinking agent,
50 to 250 ppm of a crosslinking auxiliary,
100 to 1500 ppm of a diluent, and
And 50 to 600 ppm of an antioxidant, based on the total weight of the ethylene vinyl acetate copolymer. delete delete delete The method according to claim 1,
Wherein the crosslinking aid is selected from the group consisting of triallyl isocyanurate, triallyl cyanurate, 1,4-butanedioldimethacrylate, trimethylolpropane trimethacrylate, propane trimethacrylate) or triethyleneglycol dimethacrylate. The composition for preparing a microcrosslinked ethylene vinyl acetate copolymer according to claim 1, The method according to claim 1,
Wherein said diluent is a high boiling point process oil or an isoparaffin based white spirit. &Lt; RTI ID = 0.0 &gt; 18. &lt; / RTI &gt; The method according to claim 1,
The antioxidant is selected from the group consisting of octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, Tetrakis [methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane {Tetrakis [ butyl-4'-hydroxyphenyl) propionate] methane}, Tris (4-tert-butyl- 3-hydroxy-2,6-dimethylbenzyl) isocyanurate]; Or a tris (2,4-di-tert-butylphenyl) phosphite or tris (nonylphenyl) phosphate, The composition for preparing a microcrosslinked ethylene vinyl acetate copolymer is used alone or in combination. An ethylene vinyl acetate copolymer satisfying the following conditions (a) to (d):
(a) an MI of 1.0 to 6.0 g / 10 min,
(b) a VA content of 26 to 28% by weight,
(c) a melt tension of 190 to 1000 mN at 170 DEG C, and
(d) a molecular weight distribution (Mw / Mn) (Mw: weight average molecular weight, Mn: number average molecular weight) measured by GPC of 3.5 to 4.5,
Wherein the ethylene vinyl acetate copolymer is prepared from the composition of any one of claims 1 to 7. delete A process for producing an ethylene vinyl acetate copolymer composition according to any one of claims 1 to 7, And
And a second step of melt kneading the composition at 160 to 220 ° C. 11. The method of claim 10,
In the first step, the EVA polymer, the organic peroxide, the crosslinking aid, the antioxidant, and the diluent are dry-blended, and the EVA polymer is sufficiently dispersed in the twin-screw extruder hopper before the organic peroxide decomposes.
Wherein the second step is a step of setting an extrusion condition so that a crosslinking reaction occurs and pelletizing is performed at the completion of the crosslinking reaction after the first step.