KR100632141B1 - YB-based crosslinked foam having a macroporous structure and a method of manufacturing the same - Google Patents

Abstract

In order to achieve the above object, the present invention provides a vinyl acetate, polyethylene, crosslinking agent, foaming agent, pigment, filler, additive selected according to the use and function of each product in the manufacturing method of EVA-based crosslinked foam. And blending and kneading the rubbers or resins capable of kneading and blending with the EVA resin; The composition is a low melting point spinning; The spun filament is tow or staple fiberized as a first material, and mixed with a soluble fiber selected from the group consisting of water-soluble polyvinyl alcohol (PVA) -based staple fibers, polyester-based staple fibers and natural fibers as a second material To form a nonwoven fabric; Eluting soluble fibers in the nonwoven felt; Provided is a method for producing a cross-linked EVA-based foam having a macroporous structure consisting of crosslinking and foaming a non-woven fabric in which soluble fibers are eluted.

EVA, crosslinked foam, pore structure, breathable

Description

YB-based crosslinked foam having a macroporous structure and a method for manufacturing the same {EVA CROSSLINKED FOAM HAVING PORES IN MACROSCOPIC STRUCTURE AND PREPARING THEREOF}

The present invention relates to an EVA foam having micropores in the macrostructure and a method of manufacturing the same, and in particular, by forming physical pores in the macrostructure in an EVA (Ethylene Vinyl Acetate) -based elastomer and controlling the shape and size of the pores, breathability, hygroscopicity, and sound insulation The present invention relates to an improved foam and a method for producing the same.

EVA is a kind of polyolefin resin produced from high pressure polyethylene polymerization apparatus. It is excellent in flexibility at room temperature and excellent in elasticity, and has the most similar properties to rubber. It is applied to a wide range of fields. Particularly, EVA is excellent in kneading and formability with foaming agent, crosslinking agent and other additives when applied to crosslinking foam molding, and EVA foam forms a fine uniform independent bubble structure, which is lighter than rubber and is easy to color and secondary molding. Due to its characteristics, it is widely used as a shoe sole material.                         

As a commercialized process for producing the EVA foam, crosslinking foaming, compression foaming, bead foaming, structural foaming, and the like have been proposed. Particularly, in the crosslinking foaming method, EVA has only a high density foam because the viscoelasticity is sharply lowered at the melting point or higher and the temperature range of the processing titration region is very narrow. However, crosslinking the resin can change the viscoelastic behavior, thereby widening the temperature range having viscoelasticity suitable for producing low density foams.

The foam density of the polyolefin resin foam is closely related to the physical properties of the final product, and it is divided into low density (high foaming) and high density (low foaming) based on 240 kg / m ² . Used.

As described above, as a method of implementing the pore structure in the EVA foam, a conventional rigid plate-type of various shapes and uses has a thickness of 2.5 mm or more, and the degree of non-uniformity of the surface thereof is tactile and visually easily distinguishable. Because of the use of sheet- or pellet-shaped EVA-based compositions, it is almost impossible to form macroscopic pore structures on EVA-based foams, especially when used in direct or indirect contact with the body (e.g. footwear, clothing, hats, gloves) , Bags and bedding, etc.) Due to the hermetic particle structure, which is a typical characteristic of EVA-based foamed articles having a conventional crosslinked structure, the foam has no breathability function and it is not possible to use EVA-based foams in parts / products where breathability is required. There were many limitations due to the nature of the material. However, even in the conventional method, the pores may be realized in a microstructure by low density foaming.                         

In addition, Korean Patent Publication No. 1985-5886 discloses a polyolefin-based foam fiber and a method for producing the same, in which a single fiber fineness of 0.5 to 30 denier and a fiber strength of 1.5 to 5.0 g / d is provided along the fiber axis direction. Polyolefin foam fiber having a structure in which only a composite component predominantly forms the surface, and a part of the foaming cell is cleaved on the fiber surface, and unstretched yarn having a short fiber fineness of 0.5 to 130 denier is stretched 2 to 8 times. In order to produce a composite fiber having a short fiber fineness of 0.5 to 30 denier, a foam is substantially added only to the composite component (hereinafter referred to as component B) which predominantly forms the fiber surface along the fiber side, and other composite components (hereinafter referred to as No foam is added to the component A), and each composite component has a composite ratio (component A) / (component B) of 30/70 or more and is in the cross section of the uncalculated yarn. A method for producing a polyolefin-based foam fiber is formulated so as to mix so that the theoretical average thickness of the B component is 2 to 15 µ.

The foamed fiber and the manufacturing method is already in the form of various types of fibers such as after crimping or no crimping yarn or short fiber or long fiber by controlling the foaming rate in the short fiber for various uses such as fabric, knitting, nonwoven fabric, papermaking Although it can be used, there is no specific proposal about the expression of pore structure in macrostructure and a method of controlling the same. As a result, foamed products have been desired to form a macroscopic pore structure to secure breathability and to maintain lightness and elasticity. It is possible to control the shape and size of the pores having a particle structure as much as possible, and eventually a method for effectively controlling the particle structure, physical properties, and color of each part of the EVA-based foam is desired.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide an EVA-based foam having a macroscopic pore structure in a foam and a manufacturing method thereof.

It is another object of the present invention to provide a manufacturing method and a foam thereof in which the particle structure of the foamed crosslinked EVA-based foam is dualized into a hermetic and porous structure and can be produced simultaneously through a single molded process.

Another object of the present invention is to provide a manufacturing method and a foam thereof, which simultaneously form a pore structure for securing air permeability and a crosslinked structure for securing product properties and control the shape and size of the macroscopic pore structure.

In order to achieve the above object, the present invention provides a vinyl acetate, polyethylene, crosslinking agent, foaming agent, pigments, fillers, additives and the like selected according to the use and function of each product in the manufacturing method of the EVA-based foam Blending and kneading the rubbers or resins capable of kneading and blending with the EVA resin; The composition is a low melting point spinning; The spun filament is selected from the group consisting of tow yarn or staple fiber as the first material, and a second material selected from the group consisting of water-soluble polyvinyl alcohol (PVA) -based staple fibers, polyester-based staple fibers and natural fibers. Mixing with soluble fibers to form a nonwoven fabric; Eluting soluble fibers in the nonwoven felt; Provided is a method for producing a cross-linked EVA-based foam having a macroporous structure consisting of crosslinking and foaming a non-woven fabric in which soluble fibers are eluted.

In another aspect, the present invention provides a method of eluting the soluble fiber is carried out after the cross-linking foaming step.

In addition, the present invention is a vinyl acetate, polyethylene, crosslinking agent, foaming agent, pigments, fillers, additives and rubbers that can be kneaded and blended with EVA resin in the manufacturing method of the EVA-based foam, according to the use and function of each product to prepare the EVA-based composition. Or blending and kneading the resins; The composition is a low melting point spinning; Weaving the spun monofilament into a mesh-like fabric of various tissue structures; It provides a method for producing a macroscopic pore structure formed EVA-based cross-linked foam, characterized in that consisting of the step of cross-foaming the woven fabric.

The present invention also provides a method wherein the fineness of the monofilament is 15 to 3000 denier.

In another aspect, the present invention provides an EVA-based crosslinked foam having a macroporous structure formed by the above method.

Hereinafter, a preferred embodiment of the present invention will be described in detail. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

The EVA foam according to the present invention, unlike the conventional manufacturing method, by processing the EVA-based composition in a non-woven or mesh-like material in the state before foaming, cutting or pre-molding them, the material is loaded into a mold, heated and pressurized By foam molding, the spaces present in the tissue of the nonwoven fabric or mesh material are formed into a plurality of pores in the foam-formed EVA foam, and portions except the pore portion are foam-molded in a crosslinked structure so that the physical properties of the EVA foam are unique. It is to have.

EVA composition used in the EVA-based foam according to the present invention is effective in the environment of mass production in consideration of the characteristics of each material to perform the effective mixing and kneading process between the raw materials Banbury (Bumbury), Kneader (Kneder) After first kneading using a group or the like, the material is secondly precisely kneaded through an open roll compounding machine consisting of two rolls of pre-selected specifications, and at the same time, additionally adding a master batch or other additives for pigment or color. To sufficiently disperse each material into the raw materials.

The EVA composition is an EVA resin having a vinyl acetate content index selected according to the use and function of each product, that is, a VA% (vinyl acetate content), a melt index, that is, a MI (Melt index, g / mm) value (Example 1 below) MI 3.0 g / mm, VA 22-23%), (MI 2.0g / 10min, VA content 21 weight% for example 2 below), (MI 2.2g / 10min, VA content 15 weight% for example 3 below) The main components are crosslinking agents, foaming agents, pigments, fillers and additives, and rubbers and resins (e.g., ethylene copolymers) that can be kneaded and blended with EVA resins. Add and formulate accordingly. An example of the formulation of the EVA-based composition is as follows, which may vary the vinyl acetate content (%) of the EVA base compound and other additives according to the nature, purpose, particle size, etc. of the blending material.

Example 1

EVA base compound (Melt Index 3.0 g / 10min, VA Content 22-23 wt%); 100 phr

DCP (Dicumyl peroxide) purity 98% as a crosslinking agent; 0.66 phr

JTR-M as a blowing agent; 1 phr

Stearic acid; 1 phr

ZnO ₂ ; 1 phr

75Ca-St; 1 phr

MgCO ₂ ; 8 phr

TiO ₂ as a colorant; 1 phr

Example 2

When an EVA copolymer, another polymer, and rubber are added and this is the main material of the compounding, the following is an example.

 EVA copolymer (MI 2.0 g / 10 min, VA content 21 weight%); 50 phr

Ethylene-butene copolymer 1 (Tafmer 940); 15 phr                     

Ethylene-butene copolymer 2 (Tafmer 610); 30 phr

Isoprene rubber (IR2200); 5 phr

DCP (dicumyl peroxide) as a crosslinking agent; purity 98%; 0.78 phr

ACDC as blowing agent; 2 phr

TAC as a double binder; 0.2 phr

Stearic acid; 1 phr

Zinc Oxide; 3 phr

Calcium Carbonate; 5 phr

TiO ₂ as a colorant; 4.5 phr

Example 3

When an EVA copolymer and another polymer are added and this is used as a main material of a compounding, the example is as follows.

 EVA copolymer (MI 2.2 g / 10 min, VA content 15 weight%); 75 phr

Saturated Ethylene-Octene Copolymer 1 (Engage CL 8003); 25 phr

DCP (dicumyl peroxide) as a crosslinking agent; purity 98%; 0.8 phr

ACDC as blowing agent; 2 phr

MgCO2 as a filler; 15 phr

Stearic acid; 1 phr                     

Zinc Oxide; 2 phr

Calcium Carbonate; 5 phr

TiO ₂ as a colorant; 4.5 phr

The blended and kneaded cross-linked EVA-based composition undergoes a low melting point spinning step within a temperature at which the foaming agent contained in the material is not decomposed during the process and foamed in the material state before foam molding. The spun filament may be implemented through the following two embodiments.

Example 1

The spun filament is made of tow yarn or staple fiber, which is used as a first material, and as a second material, a soluble fiber such as water-soluble polyvinyl alcohol (PVA) staple fiber, polyester staple fiber, natural Proper amount of fibers or the like may be mixed to produce a nonwoven felt. The appropriate amount may be modified according to the design structure and design of the pores of the final foamed product. In the above example, when PVA-based staple fibers are used, they are eluted before or after the foaming step.

Example 2

The spun filament is a fine filament is spun into a monofilament of 15 to 3000 denier, and then the filament is woven into a mesh-like fabric of various tissue structures. The density of the woven mesh fabric can be modified depending on the structure and design of the designed pores after foaming. Unlike the first embodiment, the present embodiment may omit the dissolution step.

The nonwoven fabric or mesh fabric formed as described above may be a finished product as an elastic body having a pore structure macroscopically confirmed as a final foam and having a predesigned shape and size through a crosslinking foaming step. The pore structure has pores larger in size than the pores secured in the nonwoven fabric or mesh fabric, and the enlargement ratio can be modified according to the foaming rate, which can be controlled by the selection of the blowing agent.

In addition, the final foam may be used as a material of the secondary compression foam molded article as necessary.

As described above, the EVA-based foam according to an embodiment of the present invention and a method for manufacturing the same may include a crosslinked structure and a macroscopic pore structure at the same time, and the shape and size of the pores may be controlled.

In addition, the structure and visual and functional effects of various foams as compared to the conventional EVA-based foams are ensured good breathability through a porous structure, and can also be provided with insulation and sound insulation. Therefore, the foam according to the present invention has an effect that can be used as footwear, bags, hats, clothing, furniture or bedding and building materials.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

Claims (5)

In the manufacturing method of the EVA foam, Blending and kneading a vinyl acetate, polyethylene, a crosslinking agent, a foaming agent, a pigment, a filler, an additive, and a rubber or resin capable of kneading and blending with an EVA resin to prepare an EVA-based composition; The composition is a low melting point spinning; The spun filament is tow or staple fiberized as a first material, and mixed with a soluble fiber selected from the group consisting of water-soluble polyvinyl alcohol (PVA) -based staple fibers, polyester-based staple fibers and natural fibers as a second material To form a nonwoven fabric; Eluting soluble fibers from the nonwoven fabric; A method for producing a cross-linked EVA-based foam having a macroscopic pore structure, characterized in that the soluble fibers are made of cross-linking foamed eluted nonwoven fabric. The method of claim 1, Eluting the soluble fiber is carried out after the cross-linking foaming step. In the manufacturing method of the EVA foam, Blending and kneading a vinyl acetate, polyethylene, a crosslinking agent, a foaming agent, a pigment, a filler, an additive, and a rubber or resin capable of kneading and blending with an EVA resin to prepare an EVA-based composition; The composition is a low melting point spinning; Weaving the spun monofilament into a mesh-like fabric of various tissue structures; Macro-porous structure of the EVA-based cross-linked foam manufacturing method characterized in that the step of cross-foaming the woven fabric. The method of claim 3, The monofilament is characterized in that the fineness is 15 to 3000 denier. EVA-based crosslinked foam having a macroporous structure produced by the method according to any one of claims 1 to 4.