KR20030084849A - Eva film for closslinking foam - Google Patents

Abstract

PURPOSE: An EVA-based film for crosslinked foam and its preparation method are provided, to allow the foam having various physical properties and shape to be obtained by preventing the early stage foaming. CONSTITUTION: The method comprises the steps of mixing an EVA-based resin, dicumyl peroxide as a crosslinking agent, JTR-M as a foaming agent, and TiO2, stearic acid, MgCO3 and ZnO as a dye; and calender molding the mixture to prepare an EVA-based film having a thickness of 0.01-2.0 mm. Also the method comprises the steps of mixing an EVA-based resin, at least two kinds of ethylene-butene copolymers, an isoprene rubber, dicumyl peroxide or TAC as a crosslinking agent, ACDC as a foaming agent, and at least one selected from the group consisting of TiO2, stearic acid, CaCO3 and ZnO as a dye; and calender molding the mixture to prepare an EVA-based film having a thickness of 0.01-2.0 mm.

Description

YB-based film for crosslinking foaming {EVA FILM FOR CLOSSLINKING FOAM}

The present invention relates to a crosslinked foamed EVA-based film, and in particular, to a film-type and to prevent premature foaming in the manufacturing step relates to an EVA-based film that can implement a variety of physical properties and shapes in the foam.

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.

It is a conventional compression or injection blowing method used for producing crosslinked EVA foam. In particular, EVA components are mainly used in footwear parts such as upper components, shoe midsoles, shoe outsoles, insoles, or unitsoles of midsole and outsole. When manufacturing the above parts with foam molded article made of material or processed products after foaming, it is usually not less than 2.5mm and the degree of nonuniformity of the surface is not only tactile and visually easy to distinguish, but also After the compression foam molding or injection foam molding process (primary process), the shoe parts are made by using the EVA-based compound for cross-linking foam having the shape of a rigid plate sheet, pellet, or chip, which cannot be processed in the specified material state. Or by compression reshaping (secondary process). The EVA composition for crosslinked foaming, such as a sheet shape used in the manufacture of conventional shoe parts, is subjected to a compression or injection foam molding step (first step) and a compression reshaping step (second step).

In such a conventional manufacturing method, it is already proven through many conventional bio-mechanics research and experiment that the parts for the bottom of the shoe is required to be differentiated for each part. In this general example, the lateral side of the rear foot of the shoe is designed to support low hardness, soft properties, and arches, which are easy to absorb the pressure generated during the first contact when walking or driving. It is preferable to effectively arrange the mechanical properties of the material for each part by hard materials or materials for bending and forefoot cushioning in the first half, and the like. However, in order to meet these demands, EVA molded materials of the conventional shape have to use a method of forming and rebonding each part having different physical properties. This method not only increases the manufacturing process, increases the manufacturing cost, but also reduces the integrity and merchandise of the bonded parts in appearance and function due to exposure of adhesive sites, invasion between boundaries, and poor adhesion. As a result, there are many limitations to realize various designs on a single molded body or part.

In addition, in order to diversify color and appearance design using conventional materials, each part had to be manufactured and then bonded together, or it had to be solved by painting, printing, etc. on the surface of the molded part by part. However, this is not only limited to the scope of application of the design and the means of expression of the design, but also the problems such as durability and productivity, cost increase.

In addition, in order to improve the functions such as wear resistance, shock absorption, stability, and comfortable fit to the shoes, different parts or properties of each part must be designed and manufactured in order to improve the functions of wearability, etc. There was a problem to have physical properties.

In addition, as the sole part of the conventional cross-linked foam molded EVA material, the midsole and the outsole were integrated, so that the selection range of the material was narrow when manufacturing the cross-linked foam molding. For example, it has been difficult to realize the weight reduction of the final molded product, the wear resistance, the multiplexing of the density of each part, etc. by the above primary foam molding process or the secondary compression molding process simultaneously on one single molded product.

In addition, in the case of using the conventional sheet-like or pellet-type cross-linked foamed EVA base compound, the manufacturing cost increases due to an additional manufacturing process and an increase in the number of molds, and it is difficult to diversify the physical properties of each part of the molded product and to diversify the design. Could not.

In addition, especially when using a sheet-like material, the surface is non-uniform, and the deviation of the scale usually has a large deviation (for example, 2.5 mm-3.0 mm) above a certain thickness, and thus the above primary foaming on the part of the shoe part After the molding process or the secondary compression reforming process, it was difficult to guarantee the quality reproducibility and consistency for color / material mutual intrusion prevention and mass production. This is because the sheet-like material has to control all the shapes of the XYZ axis, and precisely control all of them in conformity with the product design criteria in foaming or compression molding, so that the shape characteristics of the conventional materials and the characteristics of the molding process using the same are extremely realized. It is difficult.

In addition, when the primary compression-foaming molded body is molded into an EVA sponge of a large plate shape, and used as a final shoe part after cutting, surface / shape polishing, and bonding to a homogeneous molded body or other material, The amount of waste discharged during cutting and polishing operations is severe.

Therefore, various methods may be proposed to overcome the above problems, but the present inventors do not process and foam the EVA composition into a sheet or pellet form, but crosslink and foam the foam according to a predetermined design after processing the film into a film form. We found that we can solve the problem.

In order to solve the above problems, an object of the present invention is to provide a crosslinked foamed EVA composition having a thickness of 0.01 to 2.0mm, preferably 0.1 to 1.0mm.

Another object of the present invention to provide an EVA-based film that can prevent the early foaming in the manufacturing process.

Still another object of the present invention is to provide an EVA-based film which can be co-molded before and after the rolling process together with EVA film and short fiber, woven fabric, nonwoven fabric, artificial leather, foamable rubber compound and / or thermoplastic resin composition. To provide.

In order to achieve the above object, the present invention is a component of the EVA composition is blended, kneaded and rolled to form a film, the composition is EVA-based resin, DCP (Dicumyl peroxide) as a crosslinking agent, JTR-M as a foaming agent, pigment As TiO ₂ , stearic acid and MgCO ₃ , ZnO, and provides a EVA-based film for cross-linking foam is produced in a film shape having a thickness of 0.01mm to 2.0mm.

In addition, the present invention is blended, kneaded and roll-molded components of the EVA composition is produced in the form of a film, the composition contains an EVA-based resin, two or more ethylene-butene copolymer and isoprene rubber and as a crosslinking agent DCP or TAC, as a foaming agent It provides a film made of an ACDC, an inorganic material selected from the group consisting of TiO ₂ , stearic acid, CaCO ₃ and ZnO as a pigment and having a thickness of 0.01 mm to 2.0 mm.

The present invention also provides a film in which the composition is co-molded (Bi-Component Calender molding) before and after the rolling process together with short fibers, woven fabrics, non-woven fabrics, artificial leather, foamable rubber compound and / or thermoplastic resin composition.

In another aspect, the present invention provides a film having a thickness of 0.1 to 1.0mm.

In another aspect, the present invention provides a film that is processed by a low temperature process within 30 to 80 degrees Celsius during the roll forming of the film.

1 is a manufacturing process of the cross-linked foam using an EVA-based film according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, it should be noted that in the drawings, the same components or parts represent the same reference numerals as much as possible. 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.

It is to produce a film having a thickness of 0.01 to 2.0 mm, preferably 0.1 to 1.0 mm, which is a molding material of the crosslinked foamed EVA molded body of the present invention. In the case of manufacturing the EVA film with the thickness, it should be noted that the risk of early foaming is always exposed during the manufacturing process.

The EVA-based film for crosslinking foaming according to the present invention can be most effectively produced by a thin roll forming process, and in particular, linked at the end of the manufacturing process of the conventional crosslinked foamed EVA-based molding removal sheet- or pellet-type material incorporating the above materials. It can manufacture.

When explaining an embodiment of the method for producing a film according to the present invention below;

The raw materials of the film materials are primarily used in the production environment of Bumbury, Kbeader, etc., which can effectively perform the intermixing and kneading process among the raw materials in consideration of the characteristics of each material. After kneading, the secondary or precise kneading of the material is carried out through an open-type or closed-type roll mixer consisting of two rolls, usually of a standard selected according to the conditions of each workplace, and additionally added a master batch or other additives for pigments or colors. Added to sufficiently disperse each material into the raw material.

Conventional crosslinked foam EVA-based sheets and pellet materials are sufficiently subjected to the above primary foaming methods, that is, foaming methods such as normal pressure or vacuum foaming or injection molding after compression, and then the usual EVA molded foam for crosslinking foaming. Since there was no inconvenience in the foaming function of the material in manufacturing to the extent that the surface is non-uniform and the degree of non-uniformity has a typical 2.5mm to 3.0mm scale of the degree of tactile, visually easy to distinguish, and hard after room temperature cooling In the case of the sheet-like material to be oxidized, the material was usually formed only by repeating the open or closed roll compounding process several times.

On the other hand, in the case of pellet-type material, it is usually manufactured by cooling, cutting, drying, etc. after forming the material by linking it with extrusion molding in connection with the roll mixing milling at the end of the mixing and kneading. By forming the shape of the material and putting it in the material injector, injection molding was possible.

In the case of a material corresponding to the present invention, in order to perform the foam manufacturing process specified below, the material is formed by rolling molding it in conjunction with a roll mixing milling at the end of the mixing and kneading process. In this way, when the molded body is manufactured, it is possible to manufacture a molded article that was not feasible with the conventional foam molding method and the crosslinked foamed EVA compound material, and the linking process after the roll mixing milling. Is shown below.

The film-based EVA base compound material to be continuously executed after the roll mixing milling operation is prepared, or the film-based EVA base compound and other materials are prepared according to the needs of the molded product. In other words, preparation for rolling molding (Bi-Component Calender Molding) in one piece with woven fabric, nonwoven fabric, artificial leather, foamable rubber compound, thermoplastic resin composition, etc. is optionally made.

Then, in the case of an example of roll forming for film-based EVA base compound material single molding, the material having passed through the roll mixer is passed through an inverted L-type four-roll calender. In this case, since the main role of the final rolls 3 and 4 plays a major role in molding thin films of various scales specified in the present specification, it is possible to suppress the temperature rise occurring in the roll section as well as the roll forming process as a whole. This is a very important factor, and in order to exclude foaming during the processing of the blowing agent dispersed in the film material, the temperature throughout the rolling molding process should preferably be performed at a low temperature within 30 to 80 ° C., which depends on the type of blowing agent dispersed in the material. There are some differences depending on the decomposition starting temperature and the molding operation temperature conditions for foaming the molded article afterwards. In addition, if the temperature is higher than the pre-foaming may occur during the manufacturing process of the film, if the temperature is below the temperature may be pre-cured early breakage or cracking in the winding or post-process. The material passed through the roll forming roll is subsequently formed into a film-like material through a continuous process such as cooling roll, trimming, drawing, winding or cutting to an appropriate size. In addition, in the case of integral rolling molding, by forming a secondary or four-roll structure in which an auxiliary roll for linking the material of the main film with a material such as fabric or nonwoven fabric to be integrally molded at the end of the calendar roll and forming them integrally with each other, Before and after the cooling section.

Since the film of the present invention is precisely molded and has a thickness of 0.01 to 2 mm, preferably 0.1 to 1.0 mm, the film of the present invention has a thickness of 2.5 mm or more in the prior art and the non-uniformity of the surface thereof is easily tactile and visually easy. Compared to the hard plate-like or pellet-shaped material of the discriminable degree, the thickness is very diverse and thin, and the roughness variation of the surface is processed uniformly to the extent that it is difficult to visually and tactilely discriminate generally.

Films having a difference in hardness and / or color, etc. may be prepared by varying compositional ratios of the main component and the subcomponent, and may be prepared by adding a dye, etc. The processes specified in the gist may be carried out prior to the addition of material into the mold or before the process of closing the mold for heat pressurization.

This is largely distinguished from the conventional molding processes and methods in which only the weight of the material to be injected into the mold is performed manually or automatically, followed by material injection, mold closing, heating, and pressing.

The film according to the present invention cuts a plurality of films having different physical properties and colors, etc., in order to vary mechanical properties for each part of a shoe part or to diversify the design of the internal and external parts of a shoe part. After lamination and / or combination in the cavity, the final molded product can be obtained through the process of heating and pressurizing the mold to foam, thereby being simple and economical. In addition, the shoe parts in the present invention means the upper component (upper component), the insole (inner sole), midsole (midsole), outsole, midsole / outsole united sole (unit sole) and the like is not limited to any one .

(Example 1)

The main component is EVA resin (VA 3.0 g / mm, VA 22-23% in the following example) with VA (vinyl acetate content) and MI (Melt index, g / mm) values selected according to the user's application and function. Crosslinking agents, foaming agents, pigments, fillers, additives, rubbers and the like are added and formulated according to the characteristics and requirements of the final product and manufacturing process.

EVA resin (MI 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; 1 phr

Ca-St; 1 phr

MgCO ₃ ; 8 phr

TiO ₂ ; 1 phr

(Example 2)

In this embodiment, examples of the EVA copolymer, the ethylene-butene and the isoprene copolymer are given. Other conditions are the same as in Example 1 above.

EVA resin: 100 phr

EVA copolymer (MI 3.0 g / 10 min, VA content 22 to 23 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 crosslinking agent; 0.2 phr

Stearic acid; 1 phr

ZnO; 3 phr

CaCO ₃ ; 5 phr

TiO ₂ as a dye; 4.5 phr

The composition and the composition ratio were tested under conditions that do not cause premature foaming in the rolling molding step for producing a thin film as a result of many experiments of the present inventors.

Figure 1 shows a process for producing a cross-linked foam using the EVA-based film according to the present invention first prepare a plurality of cross-linked foam EVA film before the compression foam molding step. The film may have the same or different properties such as physical properties and / or colors and patterns. Next, the film is cut to fit a mold produced by shrinking it at a predetermined ratio according to the volume and shape of the final molded product. (Sa1) Next, each cut film is laminated and / or combined into the mold. In this case, the mold used is generally about 130-150% of the final molded product, and is designed / manufactured in a structure suitable for freely demolding of the molded product when the molded product is foamed, and is also reduced in size in consideration of the volume and shape of the final molded product. It is manufactured and used as a mold cavity, that is, a cavity (for example, 50 to 60% of the product specification). The same principle can be used for the processing of a sponge molded product of a large plate type, and the molded part after controlling the foaming rate and density of the individual part-shaped intermediate molded product or the large plate-shaped foamed sponge molded product is formed after the primary foam molding. In order to use as a final part, differential control is performed in material mixing and mold design with or without secondary compression reshaping. The mold is subjected to a constant temperature and pressure (typically 140-160 ° C. for compression foam molding and 160-170 ° C. for injection molding. However, the temperature and heating time are determined by the material mix ratio, the size and shape of the mold, and the use of the molded article. After the addition, (Sc1), the pressure is quickly released and the mold is opened (Sd1). At this time, the foam is decomposed in the heating process at the same time as the mold is opened, and the molded body is foamed as the gas of high temperature N ₂ , CO _2, etc. contained in the material is expanded, and the primary compression-molded molded body is the second compressed material. It is a molded part of an individual part that excludes the molding process and forms parts for use as final parts of shoes through subsidiary processes such as finishing cutting, trimming, or surface cleaning during the molding process. In the case of a molded article such as a large plate shape in which the primary compression-foamed molded body is formed for use as a final part through a subsequent simple processing process such as cutting, shape, or surface polishing, except for the secondary compression reforming process. The subsequent process after cooling and shrinking in proper state to stabilize the size, volume and general properties of the molded body Used to. When the primary compression-molded molded article is for secondary compression reshaping, about 120-140% volume or 60-70% of specific gravity of the final molded product, a compounded and designed material in consideration of the compression ratio during the secondary remolding And formed according to the conditions of the mold. To this end, the intermediate molded body is cooled to room temperature for a predetermined time in a space from which pressure is removed, and then a compression reforming process (Se1) is performed. That is, the intermediate molded body is forcibly put into a mold designed according to the shape and size of the final molded body, and the mold is closed by pressing and warming. Finally, the mold is cooled so that the final molded product can be obtained by forcibly stabilizing and then demolding a new form of the compression-reformed material. It uses the high degree of crystalline structure of polymer, which is one of common properties such as EVA, PE, or brown rubber, as is generally known. In addition to cutting to fit the mold in the cutting stage, the cross-linking foam EVA film selected according to the position or size required by the design such as the side or the bottom is inserted into the mold, and the color separation frame in the mold is used. Of course, the cutting method can be used to cut the mold. This may be another example of the present invention in that the repositioning of the material and the reforming after foaming can be further enhanced. Through the above process, even in the case of a single foamed molded product having the same physical properties and colors, the fine control is possible, so that the physical properties of each part of the shoe parts that have undergone the first compression-molded molded article or the second recompression molded process are perfect. Equalization or equalization can be advantageously implemented under mass production conditions. The identification of physical properties on a single molded body of the same physical properties and colors is conventional. The conventional injection foam molding method in which a material is melted and introduced into a closed mold and then foamed in the form of a part has a thickness of 2.5 mm or more, and the surface thereof is conventional. The first compression-foaming method or the molded body, in which a rigid plate-like or pellet-like material is injected into a mold and foamed to a degree such that the nonuniformity of the material is easily tactilely and visually determined, is compressed again in the mold. Compared to the secondary recompression molding to be remolded, it is advantageously performed on a single molded body having the same physical properties and colors due to advantages such as improved flowability in the mold cavity of the molten molding material or uniform filling of the material. By the primary compression foam molding method or secondary recompression molding method using the molded body Which it will be implemented in a short process. In particular, when manufacturing a part on a molded body having two or more physical properties and colors through a single foam molding process, the conventional primary compression foam molding method, injection foam molding method or secondary recompression molding method and the shape of materials conventionally used in each molding method As a high quality shoe parts of a combination design of color and physical properties that were not feasible, it can be inexpensively produced by a simpler process by the manufacturing method of the present invention.

As described above, the EVA-based film for crosslinking and foaming of the present invention not only has various thicknesses of 0.01 to 2 mm, preferably 0.1 to 1.0 mm, but also the degree of roughness variation of the surface is visually and tactilely uniform. In order to realize various shape designs in the material state before the foam molding process, various processing methods can be pre-processed, and in the case of foam molding, the distribution of the pre-processed or pre-formed material is characteristic of the film shape. Due to the uniformity, it can be manufactured through a simplified process that can control the fine parts of the shoe parts through the manufacturing method of the shoe parts using the film.

In addition, when the rolling process by mixing the EVA film and short fibers, etc., it is possible to implement a variety of physical properties and designs according to the design of the need to be able to manufacture a foam molding with a very free design of the final molding and a variety of physical properties and designs.

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)

The components of the EVA composition are blended, kneaded and rolled to form a film, The composition is composed of EVA-based resin, DCP (Dicumyl peroxide) as a crosslinking agent, JTR-M as a foaming agent, TiO ₂ as a pigment, stearic acid and MgCO ₃ , ZnO, and is produced in a film shape with a thickness of 0.01mm to 2.0mm EVA-based film for crosslinking foaming characterized in that. The components of the EVA composition are blended, kneaded and rolled to form a film, The composition contains an EVA-based resin, at least two ethylene-butene copolymers and isoprene rubber, and at least one inorganic material selected from the group consisting of DCP or TAC as a crosslinking agent, ACDC as a blowing agent, TiO ₂ as a pigment, stearic acid, CaCO ₃ and ZnO. EVA-based film for cross-linking and foaming, characterized in that made of a film shape having a thickness of 0.01mm to 2.0mm. The method according to claim 1 or 2, The composition is a film characterized in that it is co-molded (Bi-Component Calendermolding) before and after the rolling process with a short fiber, woven fabric, non-woven fabric, artificial leather, foam rubber compound and / or thermoplastic resin composition. The film according to claim 1 or 2, wherein the film has a thickness of 0.1 to 1.0 mm. The film according to claim 1 or 2, wherein the film is subjected to a low temperature process within 30 to 80 degrees Celsius when the film is rolled.