KR20180133607A - Ethylene vinyl acetate foam particle with excellent impact resistance and method for producing the same - Google Patents

Abstract

The present invention relates to ethylene vinyl acetate expanded particles having excellent impact resistance and a method of producing the same, and more specifically, to ethylene vinyl acetate expanded particles which have excellent softness as well as flexibility and rubber elasticity, exhibit excellent moldability, and show little permanent set; and to a method of producing the same. The ethylene vinyl acetate expanded particles, according to an embodiment of the present invention, comprise a base resin composition having an ethylene vinyl acetate resin mixed therein; show two to three endothermic peaks when heated from 0°C to 200°C at an elevation rate of 10 °C/min by heat flux differential scanning calorimetry, wherein 90% or more of closed cells having a cross-sectional diameter of 10-300 μm are formed; and have a bulk density of 15-500 g/L.

Description

TECHNICAL FIELD [0001] The present invention relates to an ethylene vinyl acetate foamed particle having excellent impact resistance and an excellent impact resistance and a method for producing the same.

The present invention relates to an ethylene vinyl acetate foamed particle having excellent impact resistance and a method for producing the same, and more particularly, to an ethylene vinyl acetate expanded particle having excellent soft feeling, flexibility, rubber elasticity, excellent molding processability, Ethylene vinyl acetate expanded particles and a process for producing the same.

Existing polyolefin particle foams are foamed polypropylene foam (EPP) or foamed polyethylene (EPE), and they are used as a shock absorber for automobiles and packaging materials for electronic products.

However, in the case of molded articles using EPP particles or EPE particles, hardnesses are high, the strength is excellent, and the use thereof is limited to a product requiring a soft feeling or an excellent buffering ability. In addition, the molded body using EPP particles or EPE particles is also vulnerable to collapse, which has the disadvantage that it is easily broken or broken.

In the case of forming a molded body using EPP particles or EPE particles, it took a very long time for stabilization and a high energy was required in manufacturing a molded body.

On the other hand, a sheet type polyolefin elastomer sheet foam, which is different from the spherical foam particles, has also been used as a packaging material or a buffering agent. However, in the case of sheet foaming, it is composed of an open cell and has low compressive strength and has heat resistance, chemical resistance, And the limit of the shape of the sheet foam, that is, the shape having the plate-like structure, has been limited in the production of a molded article using the sheet foam.

In addition, in the case of the sheet foam, the light resistance was very weak, so that not only the micro-plastic powderization by UV became very fast, but also the water absorption rate was very high and the use thereof was limited.

The present invention provides ethylene vinyl acetate expanded particles having excellent soft feeling, flexibility, rubber elasticity, excellent molding processability and low strain due to permanent compression, and a method for producing the same.

The ethylene vinyl acetate expanded particles according to one embodiment of the present invention include a base resin composition in which an ethylene vinyl acetate resin is mixed and are heated at a heating rate of 10 ° C / min at a heating rate of 0 ° C To 200 占 폚 and exhibits two or three endothermic peaks. More than 90% of closed-cell having a cross-sectional diameter of 10 to 300 占 퐉 is formed and has a bulk density of 15 to 500 g / L.

The expanded particles have an endothermic peak at a high temperature endothermic peak in the endothermic peak of 0.1 to 20 cal / g.

The expanded particles are characterized by having a bubble cell having a diameter of 150 to 300 탆 of 60% or more and a bulk density of 15 to 250 g / L.

The ethylene vinyl acetate resin may have a density of 930 to 960 g / L and a resin having a melt index (MI) of 0.1 to 50 g / 10 min (190 DEG C / 2.16 kg) And mixtures thereof.

The ethylene vinyl acetate resin is a copolymer of ethylene and vinyl acetate (VA), and the content of vinyl acetate (VA) is 5% to 40%. The backbone of polyethylene is coated with vinyl acetate VA) are randomly polymerized, or a mixture thereof.

Wherein the ethylene vinyl acetate resin is a resin selected from the group consisting of resins having a shore A hardness of 50 to 90 or a mixture thereof.

Wherein the base resin composition further comprises a polyolefin resin, wherein the polyolefin resin is selected from a resin selected from a propylene homopolymer, a propylene random copolymer, a propylene block copolymer, a propylene graft copolymer, a polyethylene, and an ethylene vinyl acetate copolymer, .

Wherein the base resin composition further comprises a polyolefin-based polymer, and the polyolefin-based polymer is selected from the group consisting of a polyolefin-based homopolymer and a copolymer of a polyolefin-based resin and -olefin selected from C ₂ to C ₂₀ alpha -olefins Or a mixture thereof.

The base resin composition further comprises at least one additive selected from the group consisting of an antioxidant, an ultraviolet stabilizer, an antistatic agent, a flame retardant, a metal deactivator, a pigment, a dye, a nucleating agent, a crosslinking agent, and a foam modifier.

Meanwhile, a method for producing ethylene vinyl acetate expanded particles according to an embodiment of the present invention comprises preparing a base resin composition in which an ethylene vinyl acetate resin is mixed, extruding the prepared base resin composition, A resin particle preparation step of producing resin particles in the form of pellets; And a foaming step of mixing the foaming agent with the resin particles and then foaming to produce expanded particles.

In the resin particle preparation step, the base resin composition contains 0.001 to 5 parts by weight, based on 100 parts by weight of the ethylene vinyl acetate resin, as a base modifier as an additive.

In the resin particle preparation step, the base resin composition may contain at least one additive selected from the group of additives consisting of an antioxidant, a UV stabilizer, an antistatic agent, a flame retardant, a metal deactivator, a pigment, a dye, a nucleating agent, Based on 100 parts by weight of the vinyl acetate resin.

In the resin particle preparation step, the base resin composition is put into an extruder, kneaded at 170 to 230 ° C, extruded into a strand shape, cooled, and then cut into pellets.

In the resin particle preparation step, the ethylene vinyl acetate resin contained in the base resin composition is a copolymer of ethylene and vinyl acetate (VA), and the content of vinyl acetate (VA) is 5% to 40% (VA) randomly polymerized on the backbone of polyethylene (polyethylene), or a mixture thereof.

Wherein the base resin composition further comprises a polyolefin resin, wherein the polyolefin resin is selected from the group consisting of a propylene homopolymer, a propylene random copolymer, a propylene block copolymer, a propylene graft copolymer, a polyethylene, an ethylene vinyl acetate And a resin selected from the group consisting of the above-mentioned resins.

In the resin particle preparation step, the base resin composition further comprises a polyolefin-based polymer, wherein the polyolefin-based polymer is a copolymer of a polyolefin-based homopolymer and a polyolefin-based resin and an? -Olefin selected from a C ₂ to C ₂₀ ? Copolymers, and mixtures thereof.

Wherein the foaming step is carried out by adding a solvent, a surfactant, and a dispersant to the resin particles and then stirring while heating. When the heating temperature reaches the foaming temperature range, a foaming agent is added and the foaming temperature range And discharging it under atmospheric pressure to foam the resin particles to produce expanded particles.

The foaming temperature range is 60 to 130 ° C, and the foaming pressure range is 10 to 50 bar.

According to the embodiment of the present invention, it is possible to apply to members requiring impact absorption performance and cushioning property as compared with conventional polyolefin-based foamed resins, members requiring excellent resilience and excellent resilience against repeated compression and permanent compression.

In addition, the molded article obtained from the foamed particles according to the present invention provides a tensile strength and a tensile strength higher than those of conventional polyolefin-based foamed molded articles, and can provide excellent flexibility without tearing when torsion or bending occurs.

The base resin composition in which the ethylene vinyl acetate (EVA) resin is mixed is excellent in the foaming property, so that it is easy to adjust the expansion ratio as required, and the foamed particles having excellent softness of elasticity and softness and the effect .

In addition, the expanded particles according to the present invention have a high ratio of independent pores, and thus can provide excellent environmental resistance such as excellent compressive strength, chemical resistance, and water resistance as compared with the sheet foam.

FIG. 1 is a graph showing an endothermic peak heat quantity in a DSC curve of a foamed particle according to an embodiment of the present invention, and FIG.
2 is a cross-sectional SEM photograph of expanded particles according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know.

The ethylene vinyl acetate expanded particles according to an embodiment of the present invention and the method for manufacturing the same may be in the form of a spherical or cylindrical bead formed by incorporating a base resin composition in which ethylene vinyl acetate (EVA) As the foam, fine independent pores having excellent soft feeling, flexibility, rubber elasticity, excellent molding process, little strain due to permanent compression, and high elasticity are formed.

Meanwhile, FIG. 1 is a graph showing an endothermic peak heat quantity in a DSC curve of a foamed particle according to an embodiment of the present invention.

Referring to FIG. 1, two to three endothermic peaks are shown, and the ethylene vinyl acetate expanded particles have two to three endothermic peaks between 60 and 120 ° C. Each endothermic peak has a non-crystalline endothermic peak and a crystalline endothermic peak. The endothermic peak at the low temperature part is formed between 60 and 80 ° C and is non-crystalline and highly influenced by the melt adhesion. The endothermic peak at the high temperature part is formed between 80 and 120 ° C and is highly crystalline.

As can be seen from FIG. 1, the expanded particles show 2 to 3 endothermic peaks in the DSC curve obtained when the temperature is elevated from 0 ° C to 200 ° C at a heating rate of 10 ° C / min by measurement of heat flux differential scanning calorimetry. Particularly, the expanded particles have an endothermic peak at a high temperature endothermic peak in the endothermic peak of 0.1 to 20 cal / g. Preferably, the endothermic peak of the high temperature endothermic peak in the endothermic peak is 0.5 to 6 cal / g

Here, the endothermic peak on the relatively low temperature side in the first-time DSC curve of the expanded particles can be regarded as being exhibited by the endotherm upon melting the ethylene vinyl acetate (EVA) resin constituting the expanded particles. The endothermic peak on the higher temperature side than the endothermic peak on the low temperature side can be regarded as the endothermic peak due to the crystal structure formed in the ethylene vinyl acetate (EVA) resin due to the bead foam process. When the foamed molded article is molded using the expanded particles, the endothermic peak on the low-temperature side affects the fusion-bondability between the expanded particles, and the endothermic peak on the high-temperature side fills the pores between the expanded particles with respect to the secondary expansion property of the expanded particles, The expanded particles are not shrunk even when a high steam pressure is added, which is an important factor for securing the moldability of the expanded molded article. Therefore, the above-mentioned expanded particles can have an excellent effect of imparting secondary extensibility during molding of the expanded molded article and excellent appearance characteristics such as small void ratio between the expanded particles without finding a depressed part on the surface of the expanded molded article.

2 is a cross-sectional SEM photograph of expanded particles according to an embodiment of the present invention.

As can be seen from Fig. 2, the foamed particles are formed as fine closed pores. At this time, the expanded particles have more than 90% of independent pores having a cross-sectional diameter of 10 to 300 mu m. The size of each of the independent pores can be adjusted according to the content and type of the additive. In order to secure excellent appearance and foaming performance at the time of forming the foamed particles, it is preferable that the cell having a diameter of 150 to 300 μm is 60% or more.

And the expanded particles have a bulk density of 15 to 500 g / L. Preferably, the expanded particles have a bulk density of 15 to 250 g / L.

A method for producing ethylene vinyl acetate expanded particles according to an embodiment of the present invention having the above-described characteristics will be described.

A method for producing ethylene vinyl acetate expanded particles according to an embodiment of the present invention comprises preparing a base resin composition in which ethylene vinyl acetate resin is mixed, extruding the prepared base resin composition, cooling and cutting the pellet A resin particle preparation step of producing a resin particle of a shape; And a foaming step of mixing the foaming agent with the resin particles and then foaming to produce expanded particles.

First, in the resin particle preparation step, a base resin composition in which an ethylene vinyl acetate resin is mixed is prepared.

The ethylene vinyl acetate resin contained in the base resin composition has a density of 930 to 960 g / L and is made of resins having a melt index (MI) of 0.1 to 50 g / 10 min (190 DEG C / 2.16 kg) , Or a mixture thereof. For example, the ethylene vinyl acetate resin is a copolymer of ethylene and vinyl acetate (VA), and the content of vinyl acetate (VA) is 5% to 40%. In the backbone of polyethylene, Acetate (VA) is randomly polymerized, or a mixture thereof.

Wherein the ethylene vinyl acetate resin may be a single resin selected from the group consisting of resins having a shore A hardness of 50 to 90 or a mixture thereof.

On the other hand, the base resin composition may further comprise a polyolefin-based resin. Here, the polyolefin resin may be selected from a resin selected from a propylene homopolymer, a propylene random copolymer, a propylene block copolymer, a propylene graft copolymer, a polyethylene, and an ethylene vinyl acetate copolymer, and a mixture thereof.

The base resin composition may further comprise a polyolefin-based polymer. Here, the polyolefin-based polymer may be selected from the group consisting of a polyolefin-based homopolymer and a copolymer of a polyolefin-based resin and an? -Olefin selected from C ₂ to C ₂₀ ? -Olefins, or a mixture thereof.

The base resin composition may further comprise at least one additive selected from the group consisting of an antioxidant, an ultraviolet stabilizer, an antistatic agent, a flame retardant, a metal deactivator, a pigment, a dye, a nucleating agent, a crosslinking agent and a bubble adjusting agent.

Preferably, fine particles of an inorganic material may be used as the bubble adjusting agent, and Talc, CaCO ₃ or ZnB may be preferably used as the additive. The foam modifier may be selected from resins having a high heat-resistant temperature, and preferably, PTFE may also be used, but is not limited thereto.

In addition, for coloring purposes, carbon black or a pigment may be mixed, and in addition to the colorant, an antistatic agent which imparts conductivity to the composition and a pigment for coloring the composition may be mixed.

The additive may be added in an amount of 0.001 to 10 parts by weight based on 100 parts by weight of the ethylene vinyl acetate resin. If the additive is contained in an amount of less than 0.001 part by weight, it may be difficult to achieve the purpose of adding the additive. In the case of carbon black, antistatic effect and coloring effect may be insufficient. When the additive is contained in an amount exceeding 10 parts by weight, It may have an influence on the physical properties, and the increase of the effect is not efficient compared with the increase of the addition amount. Particularly, it is preferable that the foam modifier is added as an additive in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of the ethylene vinyl acetate resin in order to maintain the foamability of the expanded particles well.

When the base resin composition is prepared as described above, the prepared base resin composition is put into an extruder, heated at 170 to 230 DEG C, and melt-kneaded. Then, it is extruded in a strand shape, cooled and then cut or cut while being cooled in water immediately after extrusion to produce resin pellet-shaped resin pellets called mini pellets.

In this case, the pellet-shaped resin particles may have an average weight of 0.5 to 50 mg per resin particle and a length / diameter ratio (L / D) of 0.1 to 4.

The resin particles having a weight and a length / diameter ratio are effective for obtaining uniform expanded particles upon foaming, and foamed particles can be uniformly filled into the mold using foamed particles, which is effective for producing a molded article.

On the other hand, in the foaming step, foaming agent is added to the resin particles produced in the resin particle preparation step to foam the resin particles to obtain expanded particles.

Specifically, in the foaming step, a solvent, a surfactant, and a dispersant are added together with the resin particles into a vaporizer, followed by stirring while heating. Water may be used as the solvent. The surfactant and the dispersant serve to uniformly disperse the resin particles in the solvent. Preferably, sodium alkanesulfonate may be used as the surfactant, and calcium tertiary phosphate or kaolin powder may be used as the dispersing agent. However, But is not limited thereto.

When the resin particles in the foaming machine and the solvent, the surfactant and the dispersing agent are heated and stirred while the temperature in the foaming machine is heated to a temperature higher than the foaming temperature range, that is, the glass transition temperature of the resin particles, the foaming agent is added and mixed. At this time, the foaming agent serves to foam the composition containing the resin particles, and preferably carbon dioxide, butane, or pentane gas may be used, but the present invention is not limited thereto.

When the temperature in the foaming apparatus reaches the foaming temperature range, the composition containing the resin particles mixed with the foaming agent is discharged into a low-pressure region, for example, an atmospheric pressure atmosphere while maintaining a high-pressure foaming pressure range, After cooling, it is washed and dried to obtain expanded particles. At this time, the density of the expanded particles can be controlled by controlling the temperature and the pressure of the reactor or the amount of the blowing agent during the foaming. Preferably, the foaming temperature ranges from 60 to 130 ° C and the foaming pressure ranges from 10 to 50 bar. The thus obtained expanded particles have a density of 15 to 500 g / l.

The expanded particles produced by this foaming step show 2 to 3 endothermic peaks when measured while heating from 0 ° C to 200 ° C at a heating rate of 10 ° C / min using a thermal analyzer (Differential Scanning Calorimeter). Preferably, the heat absorption amount of the high-temperature endothermic peak among the two or three endothermic peaks may be 0.1 to 20 cal / g.

In the case of expanded particles having an endothermic peak at a high temperature endothermic peak of 0.1 to 20 cal / g among them, fusion between the expanded particles occurs smoothly even at a low temperature in the production of the expanded molded article, so that the molded article can be easily produced.

When the expanded particles are produced by the above-mentioned method, an expanded molded article can be produced using the expanded particles.

When the expanded particles are produced by the above-mentioned method, an expanded molded article can be produced using the expanded particles.

The foamed molded article produced from the expanded particles manufactured according to the present invention is soft, has excellent elasticity, and is easily restored to external stress for a long period of time because of a small strain due to permanent compression, and has excellent buffering ability to absorb external impact.

At this time, the method for producing the expanded molded article using the expanded particles produced according to the present invention can be obtained by a general method known in the art, and the production method thereof is not limited to the specific method.

For example, a method for producing an expanded molded article using the expanded particles produced according to the present invention is characterized in that the prepared expanded particles are first placed in a closed container, then pressure is applied by air to form an internal pressure, Steam is supplied to expand the expanded particles. Then, it is cooled and taken out of the mold to obtain an expanded molded article.

The foamed molded article thus obtained is aged at a temperature between 60 and 90 ° C for a certain period of time according to the density to remove water contained in the cooling step of the foamed molded article to restore the shrunk part of the product.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. It is to be understood that the present invention is not limited by the scope of the present invention.

1. Preparation of pellet-shaped resin particles (resin particle preparation step)

First, the base resin composition according to Examples and Comparative Examples having the composition and content shown in Table 1 was put into an extruder and sufficiently kneaded with an extruder while heating to 170 to 230 占 폚. The kneaded base resin composition was extruded into a strand shape, cooled in water and cut into a cylindrical shape with a pelletizer to produce resin particles in the form of mini-pellets.

The ethylene vinyl acetate (EVA) resin used herein was E180F manufactured by Hanwha total Co., having a melting point of 93 ° C and a melt index (MI) of 2 g / 10 min (190 ° C, 2.16 kgf) as measured by ASTM D1238 , And A shore hardness is 94 (D shore hardness is 38).

PTEF and / or ZnB, which are foam modifiers, were used as additives, and carbon black was used as a colorant.

division Example 1 Example 2 Comparative Example 1 Example 3 Comparative Example 2 Comparative Example 3 E180F 100 100 100 100 100 100 PTFE (phr) 0.5 - - 0.25 0.5 0.0005 ZnB (phr) - 0.5 - 0.25 - - Carbon black (phr) 3 3 - 3 10 10

2. Preparation of expanded particles (foaming step)

Water, a surfactant, and a dispersant as a solvent were added to the reactor together with the resin particles obtained in the resin particle preparation step in the composition shown in Table 2, and the mixture was heated with stirring. When the temperature of the contents reached the foaming temperature range shown in Table 2 below, carbon dioxide was introduced as a blowing agent to maintain a high pressure state. Subsequently, the temperature inside the reactor was heated to maintain the foaming temperature shown in Table 2, and the discharging nozzle of the reactor was opened to release the contents in the reactor under atmospheric pressure to foam the resin particles in mini pellet form to prepare expanded particles.

In addition, carbon dioxide was continuously supplied into the reactor during the discharge to keep the pressure in the reactor constant during discharge. Thereafter, the expanded particles were washed and dehydrated, and then dried at atmospheric pressure for 8 hours or more. The peak temperature of the foamed particles was measured, and the results are shown in Table 2.

division Example 1 Example 2 Comparative Example 1 Example 3 Comparative Example 2 Comparative Example 3 Mini Pellets 24 24 24 24 24 24 water 76 76 76 76 76 76 Surfactant (phr) 0.19 0.19 0.19 0.19 0.19 0.19 Kaolin (phr) 0.16 0.16 0.16 0.16 0.16 0.16 Foaming temperature (캜) 80 80 80 80 80 80 Reactor pressure (bar) 40 40 40 40 40 40 Desnity (g / L) 89 84 235 91 86 189 DSC Secondary (cal / g) 5.6 5.9 5.7 5.7 6.0 5.6 Foaming Good Good Bad Normal Normal Bad

3. Manufacture of expanded molded article

The expanded particles obtained in Examples 1 and 2 and Comparative Examples 1 to 4 are dried naturally or using a heat source. Then, the expanded particles were filled in a mold having a cavity size of 25 cm x 10 cm x 3 cm and passed through saturated steam to heat the expanded particles, followed by cooling to obtain an expanded molded article. The obtained expanded molded article is cured in an atmosphere at 40 to 80 캜 for 4 hours and then left at room temperature for 2 hours to obtain an expanded molded article.

4. Evaluation of rebound resilience of expanded molded article

The evaluation of the coefficient of friction of the expanded molded article was based on the test method of KS M 180 8037. The rebound resilience was measured by dropping a steel ball having a diameter of 16 mm and a weight of 16.8 g at a height of 500 mm.

The test pieces were measured by making the expanded molded articles obtained in Examples 1 and 2 and Comparative Examples 1 to 4 using test pieces of 50 mm or more in the area of 100 mm x 100 mm and the results are shown in Table 3.

The evaluation of the degree of appearance, the uniformity of the cell, and the fusion state were visually confirmed, and the results are shown in Table 3 as relative values.

division Example 1 Example 2 Comparative Example 1 Example 3 Comparative Example 2 Comparative Example 3 Exterior  OK  OK  NG  Normal  Normal  BAD Cell  OK  OK  NG  OK  Normal  BAD Fusion  OK  OK  NG  OK OK  BAD Rebound resilience More than 40% More than 40% More than 50% More than 40% More than 40% More than 40%

As can be seen from Tables 1 to 3, when the foam modifier and the colorant are used as additives, when the foam modifier does not satisfy the content range proposed in the present invention (Comparative Examples 1 and 3) And it was confirmed that the foamed state was not good. When the amount of the foam modifier and the colorant were more than the content suggested in the present invention, it was confirmed that the microcells were formed or the expansion ratio was not uniform

Although the present invention has been described with reference to the accompanying drawings and the preferred embodiments described above, the present invention is not limited thereto but is limited by the following claims. Accordingly, those skilled in the art will appreciate that various modifications and changes may be made thereto without departing from the spirit of the following claims.

Claims (18)

A base resin composition in which an ethylene vinyl acetate resin is mixed,
Two to three endothermic peaks appear when the temperature is raised from 0 ° C to 200 ° C at a heating rate of 10 ° C / min by heat flux differential scanning calorimetry,
90% or more of independent bubble cells having a cross-sectional diameter of 10 to 300 mu m are formed,
Ethylene vinyl acetate expanded particles having a bulk density of 15 to 500 g / L.
The method according to claim 1,
Wherein the expanded particles have an endothermic peak at a high temperature endothermic peak in the endothermic peak of 0.1 to 20 cal / g.
The method according to claim 1,
Wherein the expanded particles have a bubble cell having a diameter of 150 to 300 占 퐉 of 60% or more and a bulk density of 15 to 250 g / L.
The method according to claim 1,
The ethylene vinyl acetate resin may have a density of 930 to 960 g / L and a resin having a melt index (MI) of 0.1 to 50 g / 10 min (190 DEG C / 2.16 kg) Ethylene vinyl acetate foam particles.
The method according to claim 1,
The ethylene vinyl acetate resin is a copolymer of ethylene and vinyl acetate (VA), and the content of vinyl acetate (VA) is 5% to 40%. The backbone of polyethylene is coated with vinyl acetate VA) is a randomly polymerized copolymer, or a mixture thereof.
The method according to claim 1,
Wherein the ethylene vinyl acetate resin is a single resin selected from the group consisting of resins having a shore A hardness of 50 to 90 or a mixture thereof.
The method according to claim 1,
Wherein the base resin composition further comprises a polyolefin resin,
Wherein the polyolefin resin is a resin selected from a propylene homopolymer, a propylene random copolymer, a propylene block copolymer, a propylene graft copolymer, a polyethylene, and an ethylene vinyl acetate copolymer, and a mixture thereof.
The method according to claim 1,
Wherein the base resin composition further comprises a polyolefin-based polymer,
Wherein the polyolefin-based polymer is a copolymer of a polyolefin-based homopolymer and a polyolefin-based resin and an? -Olefin selected from C ₂ to C ₂₀ ? -Olefins, or a mixture thereof. Acetate expanded particles.
The method according to claim 1,
Wherein the base resin composition further comprises at least one additive selected from the group consisting of an antioxidant, an ultraviolet stabilizer, an antistatic agent, a flame retardant, a metal deactivator, a pigment, a dye, a nucleating agent, a crosslinking agent and a foam modifier.
A resin particle preparation step of preparing a base resin composition in which ethylene vinyl acetate resin is mixed, extruding the prepared base resin composition, cooling and cutting to prepare pelletized resin particles;
And a foaming step of mixing the resin particles with a foaming agent and then foaming to produce expanded particles.
The method of claim 10,
In the resin particle preparation step, the base resin composition contains 0.001 to 5 parts by weight of a cell modifier as an additive, based on 100 parts by weight of the ethylene vinyl acetate resin.
The method of claim 11,
In the resin particle preparation step, the base resin composition may contain at least one additive selected from the group of additives consisting of an antioxidant, a UV stabilizer, an antistatic agent, a flame retardant, a metal deactivator, a pigment, a dye, a nucleating agent, Wherein the ethylene vinyl acetate expanded particles further contain 0.001 to 10 parts by weight based on 100 parts by weight of the vinyl acetate resin.
The method of claim 10,
Wherein the resin particle preparation step comprises kneading the base resin composition with an extruder at 170 to 230 DEG C, extruding the kneaded product into a strand shape, cooling the kneaded product, and cutting the kneaded product into pellets.
The method according to any one of claims 10 to 13,
In the resin particle preparation step, the ethylene vinyl acetate resin contained in the base resin composition is a copolymer of ethylene and vinyl acetate (VA), and the content of vinyl acetate (VA) is 5% to 40% (VA) randomly polymerized on the backbone of poly (ethylene), or a mixture thereof. The method of producing ethylene vinyl acetate expanded particles according to claim 1, wherein the vinyl acetate (VA)
The method according to any one of claims 10 to 13,
In the resin particle preparation step, the base resin composition further comprises a polyolefin resin,
Wherein the polyolefin resin is a resin selected from a propylene homopolymer, a propylene random copolymer, a propylene block copolymer, a propylene graft copolymer, a polyethylene, and an ethylene vinyl acetate copolymer, and a mixture thereof. Gt;
The method according to any one of claims 10 to 13,
In the resin particle preparation step, the base resin composition further contains a polyolefin-based polymer,
Wherein the polyolefin-based polymer is a copolymer of a polyolefin-based homopolymer and a polyolefin-based resin and an? -Olefin selected from C ₂ to C ₂₀ ? -Olefins, or a mixture thereof. A process for producing acetate expanded particles.
The method of claim 10,
Wherein the foaming step is carried out by adding a solvent, a surfactant, and a dispersant to the resin particles and then stirring while heating. When the heating temperature reaches the foaming temperature range, a foaming agent is added and the foaming temperature range Wherein the resin particles are discharged under atmospheric pressure to foam the resin particles to produce expanded particles.
18. The method of claim 17,
Wherein the foaming temperature range is from 60 to 130 ° C, and the foaming pressure range is from 10 to 50 bar.

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