KR20200034072A - A resin composition with hybrid blowing agents which are improved shrinkage - Google Patents

Abstract

The present invention relates to a mixed foaming agent comprising a chemical foaming agent and a physical foaming agent and, more specifically, to a mixed foaming agent comprising a chemical foaming agent and a physical foaming agent and to a resin composition comprising the same. In particular, the mixed foaming agent where an inorganic chemical foaming agent and a physical foaming agent which is a thermally expandable microsphere are mixed is applied to the resin composition to solve conventional problems.

Description

A resin composition with hybrid blowing agents which are improved shrinkage}

The present invention relates to a mixed foaming agent comprising a chemical foaming agent containing sodium bicarbonate and a physical foaming agent in the form of a core-shell, and a resin composition containing the same and improving shrinkage.

Foam or sponge is prepared by mixing a blowing agent into a resin or polymer, placing it in a mold, heating and pressing.

The foaming process as described above is largely divided into chemical foaming using a chemical foaming agent and physical foaming using a physical foaming agent such as a capsule-type foaming agent. When chemical or physical blowing agents are used alone, there are disadvantages that are difficult to complement each other.

Chemical blowing agents have a problem in that harmful gases such as ammonia and formamide are generated during processing.

In order to solve this, the development of physical blowing agents such as thermally expandable microspheres using a physical foaming mechanism has been conducted. It uses a mechanism in which the hydrocarbons in the microspheres are phase-changed and expanded by heat. Specifically, the heat-expandable microspheres are in the form of sealing the hydrocarbons in the outer resin, and when heat is applied, the hydrocarbons are transferred to the gas phase to cause a large volume expansion, which causes the volume of the blowing agent to expand by about 50 times or more.

The thermally expandable microspheres compensate for disadvantages such as the problem of generating harmful gases of the chemical foaming agent, but the foaming rate of the final product is lower than that of the chemical foaming agent, and although there are differences depending on the resin, it is difficult to obtain a uniform foam.

Among chemical foaming agents, foaming may be performed through an endothermic reaction using sodium bicarbonate (NaHCO ₃ , hereinafter referred to as sodium bicarbonate), an inorganic foaming agent. In this case, economic efficiency and foam pressure are relatively excellent. However, there is a problem in that dimensional stability is unstable due to shrinkage problems after foaming.

Korean Patent Publication No. 2017-0055437 relates to a foamed polystyrene composition and a method of manufacturing an extruded polystyrene foam using the same, and uses sodium hydrogen carbonate as a chemical foaming agent. Particularly, the use of expanded graphite powder improves thermal insulation properties and discloses a feature of suppressing strain due to direct sunlight, but has not suggested a solution to shrinkage caused by using a chemical blowing agent.

Korean Patent Publication No. 2015-025523 relates to a foaming agent composition comprising a hydrazide-based foaming agent and an inorganic foaming agent, and discloses that sodium bicarbonate, ammonium bicarbonate, and the like are used as the inorganic foaming agent. However, a solution to the phenomenon of shrinkage after forming the foam has not been proposed.

Korean Patent Publication No. 2017-0055437 Korean Patent Publication No. 2015-0125523

The present invention is to solve the above problems, the specific purpose is as follows.

The present invention aims to present a suitable foaming form through a combination of an inorganic foaming agent and a physical foaming agent among chemical foaming agents.

Thermally expandable microspheres have a lower internal pressure than chemical foaming agents, so it is difficult to expect a high foaming rate. The present invention has a technical feature that a physical foaming agent and a chemical foaming agent are appropriately mixed to cope with this. Specifically, it is chemically applied to base resins of EVA (Ethylene Vinyl Acetate copolymer), PVC (Poly Vinyl Chloride), and SBR (Styrene-butadiene Rubber) to be applied to products that require white coloring such as shoes, sandals, mats, and wallpaper. A hybrid blowing agent is used which is a mixture of blowing agent and physical blowing agent. In addition, it is intended to be applied to shoes, sandals, mats, wallpaper, etc. by implementing a foam that has an appropriate foaming ratio suitable for the intended use according to an appropriate foaming agent content and, in particular, can solve the shrinkage problem after foaming.

The present invention is a base resin; And it includes a chemical blowing agent and a foaming agent comprising a physical blowing agent, the chemical blowing agent is an inorganic foaming agent, the physical blowing agent provides a resin composition comprising a mixed foaming agent having an improved thermal expansion microsphere shrinkage.

The base resin may be selected from the group consisting of ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC), styrene-butadiene rubber (SBR), and combinations thereof. have.

The inorganic foaming agent may be sodium bicarbonate (NaHCO ₃ ).

The thermally expandable microspheres include an outer shell comprising a thermoplastic resin; And a foaming compound encapsulated in the shell.

The thermoplastic resin is acrylonitrile (AN), methaacrylonitrile (MAN), methyl methacrylate (Methylmethacrylate, MMA), methacrylic acid (MAA), acrylic acid (Acrylic acid, AA) and combinations thereof, and the foaming compound is composed of hydrocarbons, iso-butane, iso-pentane, hexane, octane (Octane) and combinations thereof.

The resin composition may include 2 parts by weight to 5 parts by weight of the mixed foaming agent based on 100 parts by weight of the base resin.

The mixed foaming agent may include the chemical blowing agent and the physical blowing agent in a mass ratio of 1: 0.5 to 1: 1.

The resin composition may further include additives selected from the group consisting of stabilizers, foaming accelerators, fillers, lubricants, crosslinking agents, crosslinking accelerators, plasticizers, and combinations thereof.

One form of the resin composition is 100 parts by weight of a blend resin of ethylene-vinyl acetate (EVA) or ethylene-vinyl acetate (EVA) and low-density polyethylene (LDPE) as the base resin; 1 to 3 parts by weight of sodium bicarbonate (NaHCO ₃ ) as the chemical blowing agent; As the physical foaming agent, the outer shell is selected from the group consisting of acrylonitrile (AN), methacryrylonitrile (MAN), and combinations thereof, and the thermal expansion property of the foaming compound is iso-Pentane 1 to 3 parts by weight of microspheres; Foaming accelerator 1 to 5 parts by weight; 10 to 30 parts by weight of filler; 1 to 5 parts by weight of lubricant; And 0.1 to 2 parts by weight of a crosslinking agent.

Another form of the resin composition is 100 parts by weight of polyvinyl chloride (PVC) as the base resin;

1 to 3 parts by weight of sodium bicarbonate (NaHCO ₃ ) as the chemical blowing agent; As the physical foaming agent, the outer shell is selected from the group consisting of acrylonitrile (AN), methacryrylonitrile (MAN), and combinations thereof, and the thermal expansion property of the foaming compound is iso-Pentane 1 to 3 parts by weight of microspheres; Stabilizer 1 to 5 parts by weight; 10 to 50 parts by weight of filler; 1 to 5 parts by weight of lubricant; And 50 to 200 parts by weight of a plasticizer.

Another form of the resin composition is 100 parts by weight of styrene-butadiene rubber (SBR) as the base resin; 1 to 3 parts by weight of sodium bicarbonate (NaHCO ₃ ) as the chemical blowing agent; As the physical foaming agent, the outer shell is selected from the group consisting of acrylonitrile (AN), methacryrylonitrile (MAN), and combinations thereof, and the thermal expansion property of the foaming compound is iso-Pentane 1 to 3 parts by weight of microspheres; Foaming accelerator 1 to 5 parts by weight; 1 to 5 parts by weight of lubricant; 1 to 5 parts by weight of a crosslinking agent; And 0.1 to 2 parts by weight of a crosslinking accelerator.

In the foam according to the present invention, the resin composition may be foamed.

The foam may be a midsole / insole / outsole of shoes, wallpaper or mat.

According to the present invention, when using only the chemical blowing agent, it is possible to reduce the amount of harmful gas generation and provide a foam having excellent foaming performance and dimensional stability.

When the resin composition according to the present invention is used, it is possible to obtain a foam having clear bubbles and an even surface.

According to the present invention, there is an effect that it is possible to increase the expandability when using only thermally expandable microspheres, which are physical foaming agents, as foaming agents.

Figure 1 shows a photograph of the foam prepared according to the method of Example 1 and Comparative Example 1 when the base resin is made of EVA.
Figure 2 shows a photograph of the foam prepared according to the method of Example 2 and Comparative Example 2 when the base resin is made of PVC.
Figure 3 shows a photograph of the foam prepared according to the method of Example 3 and Comparative Example 3 when the base resin is SBR.

The above objects, other objects, features and advantages of the present invention will be readily understood through the following preferred embodiments related to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed contents are thorough and complete and that the spirit of the present invention is sufficiently conveyed to those skilled in the art.

In describing each drawing, similar reference numerals are used for similar components. In the accompanying drawings, the dimensions of the structures are shown to be enlarged than the actual for clarity of the present invention. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this specification, the terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described herein, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, actions, components, parts or combinations thereof are not excluded in advance. In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case "directly above" the other part but also another part in the middle. Conversely, when a portion of a layer, film, region, plate, or the like is said to be “under” another portion, this includes not only the case “underneath” the other portion but also another portion in the middle.

Unless otherwise specified, all numbers, values, and / or expressions expressing the amounts of ingredients, reaction conditions, polymer compositions and formulations used herein are those numbers that occur in obtaining these values, among other things. As these are approximations that reflect the various uncertainties of the measurement, it should be understood that in all cases they are modified by the term "about". In addition, when numerical ranges are disclosed in this description, these ranges are continuous, and include all values from the minimum value in this range to the maximum value including the maximum value, unless otherwise indicated. Further, when such a range refers to an integer, all integers including the minimum value to the maximum value including the maximum value are included unless otherwise indicated.

In the present specification, when a range is described for a variable, it will be understood that the variable includes all values within the described range including the described endpoints of the range. For example, a range of “5 to 10” includes values of 5, 6, 7, 8, 9, and 10, as well as any subrange of 6 to 10, 7 to 10, 6 to 9, 7 to 9, and the like. It will be understood to include, and include any value between integers pertinent to the stated range of ranges such as 5.5, 6.5, 7.5, 5.5 to 8.5 and 6.5 to 9, and the like. Also, for example, the range of “10% to 30%” is 10% to 15%, 12% to 10%, 11%, 12%, 13%, etc., and all integers including up to 30%. It will be understood that it includes any subranges such as 18%, 20% to 30%, etc., and also includes any value between valid integers within the scope of the stated range, such as 10.5%, 15.5%, 25.5%, and the like.

The resin composition comprising the mixed foaming agent with improved shrinkage according to the present invention includes a base resin; And mixed blowing agents including chemical blowing agents and physical blowing agents. The chemical foaming agent is an inorganic foaming agent, and the physical foaming agent is a thermally expandable microsphere.

Hereinafter, the configuration of the present invention will be described in detail.

The base resin is selected from the group consisting of ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC), styrene-butadiene rubber (SBR), and combinations thereof.

The base resin may be provided in the form of pellets and bales. However, it is not limited thereto, and may be provided in the form of powder, granule, and flake.

The base resin is compounded with a kneader, an open roll, etc. together with the mixed foaming agent, and then foamed by a method such as extrusion, injection, or compression molding to produce a foam. You can.

The EVA, PVC and SBR are excellent in heat resistance and cold resistance, and have little deformation according to temperature. In addition, it has strong fusion, excellent stiffness, and excellent shock absorption and resilience. In addition, it has excellent oil and chemical resistance, flame retardant treatment, and in particular, it does not generate toxic gases (such as dioxin) during incineration, and is chemically stable, thereby securing stability to the human body and the environment.

The present invention is one technical feature of using the inorganic foaming agent (hereinafter, a chemical inorganic foaming agent) as the chemical foaming agent.

The inorganic blowing agent is preferably sodium bicarbonate (Sodium hydrogen carbonate, NaHCO ₃ ). At this time, if a foaming agent other than the sodium bicarbonate is used as the chemical inorganic foaming agent, the bubble nucleation effect is deteriorated, which adversely affects productivity.

In the present invention, the physical foaming agent is characterized in that it is a thermally expandable microsphere.

The thermally expandable microspheres include an outer shell and a foaming compound enclosed in the outer shell. The thermally expandable microspheres have a core-shell structure.

The average particle diameter of the thermally expandable microspheres is not particularly limited, but is preferably 10 to 100 μm. More preferably, it is 10 to 50 µm. If the average particle diameter of the thermally expandable microspheres is less than 10 μm, the expansion performance of the microspheres may be lowered, and if the average particle diameter exceeds 100 μm, the filling efficiency of the foaming compound decreases, and when mixed with the base resin, workability may decrease. have. The average particle diameter can be measured using a commercially available laser diffraction scattering type particle size distribution measuring device, for example, a micro track particle size distribution measuring device. In addition, 200 particles may be arbitrarily extracted from the electron micrograph and an average particle diameter may be calculated.

The thermally expandable microspheres contain 10 to 50% by weight, preferably 10 to 40% by weight, of the foaming compound based on the total weight of the thermally expandable microspheres.

The temperature for initiating expansion of the thermally expandable microspheres is not particularly limited, but is preferably 80 ° C to 200 ° C. It is more preferably 100 ° C to 190 ° C. At this time, when the expansion start temperature is less than 80 ° C, the heat resistance is low and the expansion performance of the thermally expandable microspheres may be lowered. In addition, when the temperature exceeds 200 ° C, the maximum foaming temperature increases and the expansion performance of the thermally expandable microspheres may deteriorate.

It is preferable that the maximum expansion temperature of the thermally expandable microspheres is less than 300 ° C. If it is outside the above range, sufficient foaming magnification cannot be obtained.

The thermally expandable microspheres are excellent in heat resistance, and thus are preferable for use in injection molding and the like.

The maximum expansion ratio of the thermally expandable microspheres is 20 to 200 times. It is preferably 50 to 180 times. When the maximum expansion magnification exceeds 200 times, the surface of the foam containing the thermally expandable microspheres may be irregular and rough.

The method of manufacturing the thermally expandable microspheres includes preparing an oil phase comprising a thermoplastic monomer and a foaming compound; Preparing an aqueous phase comprising distilled water and a dispersion stabilizer; Mixing the oil phase and the water phase to form a suspension; And suspension polymerization of the suspension to produce thermally expandable microspheres.

The thermoplastic monomer is acrylonitrile (AN), methacrylonitrile (MAN), methyl methacrylate (Methylmethacrylate, MMA), methacrylic acid (MAA), acrylic acid (Acrylic acid, AA) and combinations thereof.

The foaming compound is selected from the group consisting of iso-Butane, iso-Pentane, Normal pentane, N-pentane, Hexane, Octane, and combinations thereof. It may be a hydrocarbon (Hydrocarbon).

The oil phase of the present invention may further include an organic solvent as necessary in addition to the thermoplastic monomer and the foaming compound.

The oil phase of the present invention may be prepared by mixing the thermoplastic monomer, a foaming compound, an organic solvent, and the like.

The dispersion stabilizer may be selected from the group consisting of Colloidal Silica (C.S), aluminasol, magnesium hydroxide, and combinations thereof. It may be preferably colloidal silica.

When the thermally expandable microspheres are used in combination with a chemical inorganic foaming agent, the whiteness and yellowing effect are locally improved compared to the case of using the conventional thermally expandable microspheres.

The method of mixing the oil phase and the water phase in the step of forming the suspension is not particularly limited, for example, the oil phase may be mixed with the water phase, the water phase may be mixed with the water phase, and the water phase and the oil phase are respectively in separate containers. It can also be added and mixed. However, an additional homogenizer can be used to increase the shear stress to help dispersion.

In the present invention, the weight ratio of the oil phase and the water phase is 20:80 to 40:60. When it is out of the above range, in controlling the average particle diameter of the thermally expandable microspheres, there is a high probability that small particles less than 10 µm will be distributed, and the amount of hydrocarbons present in the oil phase is low, so the foaming rate is low, so it functions properly as a blowing agent. It may not be possible. In addition, when the synthesis reaction is started after mixing with a homogenizer, the viscosity rises rapidly during initiation and crosslinking, so that the rotational shear force cannot be applied to the reactant, so that the synthesis of the thermally expandable microspheres may become impossible.

The suspension can be obtained by mixing the aqueous phase and the oil phase at 1000 to 1500 rpm for 10 to 30 minutes using a homogenizer. If it is less than 1000 rpm, the mixing of the water phase and the oil phase may not be properly performed, and thus the particle size deviation of the thermally expandable microspheres may be large. In addition, if less than 10 minutes, the water phase and the oil phase may not be properly mixed, so that droplets may not be formed, and if it exceeds 30 minutes, the amount of the blowing agent may be reduced by evaporation of hydrocarbons, which are boiling points at or below room temperature.

To the suspension, a polymerization initiator such as t-butyl peroxy acetate, diisopropylbenzene hydroperoxide, surfactant, and the like can be further added.

The "suspension polymerization" means polymerization in a state in which a water phase and an oil phase are mixed. Accordingly, a crosslinkable portion in the suspension is crosslinked to form a shell, and a thermally expandable microsphere containing hydrocarbons can be formed inside the shell.

Specifically, the suspension polymerization, suspension polymerization is carried out in a reactor having a structure capable of applying pressure, a temperature increase reaction and a rotational force.

In the suspension polymerization, the pressure is 1 to 5 kgf / cm ² . At this time, if it is less than 1kgf / cm ² , the viscosity does not rise sufficiently, so that even shear force due to rotation of the impeller may not occur, and when it exceeds 5kgf / cm ² , it may be difficult to control the particle size of the thermally expandable fine particles. In addition, the rotational force may be 50 to 800 rpm. If it is out of the above range, it may be difficult to control the particle size of the thermally expandable microspheres.

The rotational shear force is applied by the impeller structure of the reactor, and the temperature during polymerization is performed at 50 ° C to 70 ° C.

The resin composition may include 2 parts by weight to 5 parts by weight of the mixed foaming agent based on 100 parts by weight of the base resin.

The mixed foaming agent may include the chemical inorganic foaming agent and the physical foaming agent in a mass ratio of 1: 0.5 to 1: 1. When the mass ratio of the physical foaming agent exceeds the above range, the whiteness of the foam produced by foaming the resin composition may be lowered and the foaming ratio may be lowered. When the mass ratio of the physical foaming agent is less than the above range, the surface of the foam may not be smooth. The cross-linking process is necessary and the process convenience may decrease.

The resin composition may further include an additive. The additive may be selected from the group consisting of stabilizers, foaming accelerators, fillers, lubricants, crosslinking agents, crosslinking accelerators, plasticizers, rubbers and combinations thereof.

The stabilizer is a conventional PVC stabilizer in solid or liquid form, for example, Ca / Zn, Ba / Zn, Pb, Sn or an organic compound (OBS) -based stabilizer.

As the foaming accelerator, any one selected from the group consisting of magnesium oxide, mercury oxide, tin oxide, cadmium oxide, lead oxide, calcium oxide, zinc oxide, and combinations thereof is used.

As the filler, any one selected from the group consisting of magnesium, aluminum, silicon, titanium, calcium carbonate, and combinations thereof is used.

Zinc stearate or stearic acid is used as the lubricant.

The crosslinking agent may be selected from sulfur, insoluble sulfur and organic peroxide. The organic peroxide is preferably t-butyl peroxy isopropyl carbonate, t-butyl peroxy laurate, benzoyl peroxide, or t-butyl Peroxyacetate, t-butyl peroxy benzoate, di-t-butyl diperoxy phthalate, thi-butyl peroxymalic acid (t-butyl peroxy maleic acid), cyclohe xanone peroxide, t-butyl cumyl peroxide, t-butyl hydrop eroxide, 1-1 -Bis- (T-butyl peroxy) -3,3,5-trimethylcyclohexane (1,1-bis- (t-butyl peroxy) -3,3,5-trimethyl c yclohexane), dikyl peroxide (dicumyl peroxide), 2,2-bis- (t-butyl peroxy) butane (2,2-bis- (t-butyl peroxy) b utane), methyl ethyl keton peroxide, 1,1- D- (T-Boo Peroxy) cyclonucleic acid (1,1-di- (tbutylperoxy) cyclohexane), 2,5-dimethyl-2,5-di- (thi-butylperoxy) nucleic acid-3 (2,5-dimethyl-2, 5-di- (t-butylperoxy) h exane-3), 2,5-dimethyl-2,5-di- (bentoylperoxy) hexane-3 (2,5-dimethyl-2,5-di- (benzoylperoxy) ) hexyne-3), 2,5-dimethyl-2,5-di (benzoylperoxy) hexane (2,5-dimethyl-2,5-di (benzoylperoxy) hexane), 2,5-dimethyl-2, 5-di- (benzoylperoxy) hexane-3 (2,5-dimethyl-2,5-di- (benzoylperoxy) hexyne-3), 2,5-dimethyl-2,5-di (benzoylperoxy) hexane -3 (2,5-dim ethyl-2,5-di (benzoylperoxy) hexane-3), di-t-butylperoxide, en-butyl-4,4-bis (Ti- Butylperoxy) valate (n-butyl-4,4-bis (t-butylperoxy) valelate), 2,2'-bis (butylperoxy isopropyl) benzene (2,2'-bis (butylperoxy isopropyl) benzene ) And any combination selected from the group consisting of these.

The crosslinking accelerator may be selected from Thiazole, Sulfenamide, Thiocarbamate, Guanidine, Thiurame or Thiourea. Preferably mercaptobenzothiazole (MBT), dibenzothiazole disulfide (MBTS), zinc salt of 2-mercaptobenzothiazole (ZnMBT), tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), Tetraethylthiuram Sulfide (TETD), Tetrabutylthiuram Sulfide (TBTD), Dipentamethylene Thiuram Tefrasulfide (DPTT), Zinc Diethyl Dithiocarbamate (ZDEDC), Zinc Dienbutyl Diti Any one selected from the group consisting of okabamate (ZDBDC), zinc ethylpentyl dithiocarbamate (ZEPDC), zinc dimethyldithiocarbamate (ZDMDC), and combinations thereof is used.

As the plasticizer, plasticizers commonly used for soft use of vinyl chloride resins, that is, phthalate plasticizers such as dioctyl phthalate and diisodecyl phthalate, dioctyl adipate, dibasic carboxylate dibasic acid ester plasticizers, tri Any one selected from the group consisting of merit acid ester plasticizer, polyester plasticizer, and combinations thereof is used.

In the resin composition according to an embodiment of the present invention, the base resin may be ethylene-vinyl acetate (EVA), or a blend of ethylene-vinyl acetate (EVA) and low density polyethylene (LDPE). At this time, the resin composition is based on 100 parts by weight of the base resin, 1 to 3 parts by weight of a chemical inorganic foaming agent and a physical blowing agent, 1 to 5 parts by weight of a foaming accelerator, 10 to 30 parts by weight of a filler, and 1 to 5 parts by weight of a lubricant Parts and 0.1 to 2 parts by weight of a crosslinking agent.

In the resin composition according to another embodiment of the present invention, the base resin may be polyvinyl chloride (PVC). At this time, the resin composition is based on 100 parts by weight of the base resin, 1 to 3 parts by weight of a chemical inorganic foaming agent, 1 to 3 parts by weight of a physical blowing agent, 1 to 5 parts by weight of a stabilizer, 10 to 50 parts by weight of a filler, and 1 lubricant It may include 5 to 5 parts by weight and 50 to 200 parts by weight of a plasticizer.

In the resin composition according to another embodiment of the present invention, the base resin may be styrene-butadiene rubber (SBR). At this time, the resin composition is based on 100 parts by weight of the base resin, 1 to 3 parts by weight of a chemical inorganic foaming agent, 1 to 3 parts by weight of a physical blowing agent, 1 to 5 parts by weight of a foaming accelerator, 1 to 5 parts by weight of a lubricant, and a crosslinking agent 1 To 5 parts by weight and 0.1 to 2 parts by weight of a crosslinking accelerator.

The present invention foams the resin composition to form a foam.

Specifically, the base resin is compounded with a kneader, an open roll, etc. together with the mixed foaming agent, and then foamed under high temperature and high pressure by extrusion, injection, or compression molding. Or, after using a calender roll or an open roll for mixing in the form of a sheet, form a foam.

It is characterized in that the foam is foamed by pressing at a high temperature.

According to the present invention, the foam is characterized in that it can be applied to a window (midsole / insole / outsole), wallpaper or mat of shoes or sandals.

Specifically, in the case of a shoe sole and a mat in the present invention, a base resin blended with EVA and PE (LDPE or LLDPE) is used. When the EVA is used as a main material, it is easy to lighten during the foaming process, and elasticity, resilience, and cushioning are improved. In addition, when blending the base resin with LDPE or LLDPE over a certain amount, LDPE or LLDPE is non-polar compared to EVA, which may cause difficulties when bonding the sole to the upper. Also, when applied to the unit-sole rather than the outsole or midsole, there are cases where a rubber material is adhered to the front and rear parts of the floor where a lot of wear occurs. When a large amount of the polymer composed of the main chain) is blended, adhesion is not easy.

In the case of sandals in the present invention, PVC is used as a base resin to improve price competitiveness and productivity. When using the PVC as a base resin, DOP (Dioctyl Phthalate) can be used as a plasticizer. At this time, PVC is mixed with DOP to undergo curing through interaction at high temperatures. Accordingly, it is preferable that PVC and DOP are applied 1: 1. In addition, in the present invention, SBR can also be used as a base resin for sandals. When the SBR is used as a base resin, it is a feature that a traditional vulcanization process can be used. Accordingly, when using the SBR as a base resin, it is preferable to add sulfur to the additive and heat it to change elasticity.

In the case of the wallpaper in the present invention, a mixture of PVC and DOP is applied, but a method of heating for 30 seconds to 1 minute at a high temperature after casting thinly (less than 1T) is applied, so a mixed foaming agent and a stabilizer requiring heat resistance thereto are applied. It should be applied appropriately.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are only examples to aid the understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

<Example 1, Comparative Example 1 and Comparative Example 2>

A resin composition according to an embodiment of the present invention described above was prepared. Specifically, according to the ratio shown in Table 1, the resin compositions of Example 1, Comparative Example 1 and Comparative Example 2 were prepared.

Resin composition composition Example 1
(Parts by weight) Comparative Example 1
(Parts by weight) Comparative Example 2
(Parts by weight) Base resin EVA
(EVA: LDPE = 80: 20) 100 100 100 Chemical blowing agent NaHCO ₃
(Geumyang Corporation) 2 4 - Physical blowing agent Thermal expansion microsphere
(CAP / 563J, Geumyang Co., Ltd.) 2 - 4 additive Foaming accelerator ZnO
(KS-1, Hanil Chemical Industry) 3 3 3 Filler CaCO ₃
(Yujin Industrial Co., Ltd.) 20 20 20 slush St / A
(Stearic acid, LG) One One One Crosslinker DCP
(Dicumyl peroxide) 0.9 0.9 0.9

<Example 2, Comparative Example 3 and Comparative Example 4>

A resin composition according to another embodiment of the present invention described above was prepared. Specifically, according to the ratio shown in Table 2, the resin compositions of Example 2, Comparative Example 3 and Comparative Example 4 were prepared.

Resin composition composition Example 2
(Parts by weight) Comparative Example 3
(Parts by weight) Comparative Example 4
(Parts by weight) Base resin PVC
(LP-090, LG) 100 100 100 Chemical blowing agent NaHCO ₃ (Geumyang) 2 4 - Physical blowing agent Thermal expansion microsphere
(CAP / 563J, Geumyang Co., Ltd.) 2 - 4 additive Stabilizer PVC Stabilizer
(Ca-St, Dansuk) 2.5 2.5 2.5 Filler CaCO ₃
(Yujin Industrial Co., Ltd.) 50 50 50 slush St / A
(Stearic acid, LG) One One One Plasticizer DOP
(Dioctyl phthalate, Siyaku) 100 100 100

<Example 3, Comparative Example 5 to Comparative Example 8>

A resin composition according to another embodiment of the present invention described above was prepared. Specifically, according to the ratio shown in Table 3, the resin compositions of Example 3 and Comparative Examples 5 to 8 were prepared.

Resin composition composition Example 3
(Parts by weight) Comparative Example 5
(Parts by weight) Comparative Example 6
(Parts by weight) Comparative Example 7
(Parts by weight) Comparative Example 8
(Parts by weight) Base resin SBR 100 100 100 100 100 Chemical blowing agent NaHCO ₃
(Geumyang Corporation) 2 4 - One 3 Physical blowing agent Thermal expansion
Smile
(CAP / 563J,
Geumyang Co., Ltd.) 2 - 4 3 One additive Foaming accelerator ZnO
(KS-1, Hanil Chemical Industry) 3 3 3 3 3 slush St / A
(Stearic acid, LG) 3 3 3 3 3 Crosslinker Sulfur One One One One One Crosslinking accelerator TT
(Accelerator) 0.5 0.5 0.5 0.5 0.5

Experimental example

<Examples 1 to 3 and Comparative Examples 1 to 3>

Foams were prepared using the resin compositions of Examples 1 to 3 and Comparative Examples 1 to 6, and the observed results were analyzed as follows. The foaming rate (%) and shrinkage (%) are shown in Table 4 below.

Example 1 Comparative Example 1 Comparative Example 2 Example 2 Comparative Example 3 Comparative Example 4 Example 3 Comparative Example 5 Comparative Example 6 Firing rate
(%) 185 205 168 175 180 162 184 190 167 Shrinkage
(%) 13.0 25.3 10.4 8.1 21.5 6.9 9.8 22.7 7.2 Firing rate
evaluation O O X O O X O O X Shrinkage evaluation O X O O X O O X O Evaluation criteria for foaming rate: O-When the foaming rate is more than 170%, X-When the foaming rate is less than 170%
Criteria for shrinkage evaluation: O-when shrinkage is less than 15%, X-when export rate is more than 15%

Measurement method:
(1) Shrinkage: measured after cooling for 24hr at room temperature after demoding.
(2) Foaming ratio: The foaming ratio of the foam was calculated by the ratio of the diagonal length (L) of the mold bottom to the diagonal length (m) of the foam bottom. The percentage of foaming rate was expressed as m / LX 100.

Referring to Table 4, which is the result of the above experiment, Example 1 shows results satisfying all the criteria of the present invention with a foaming rate of 185% and a shrinkage rate of 13.0%, whereas Comparative Example 1 does not reach the criterion of shrinkage In the case of Comparative Example 2, it did not show satisfactory results in the foaming rate. Through this, it can be expected that the foam of Example 1 has excellent foaming performance and excellent dimensional stability.

Figure 1 shows a photograph of the foam prepared using the resin composition of Example 1 and Comparative Example 1. It can be seen that the foam according to Example 1 of the figure has clear and even bubbles compared with the foam according to Comparative Example 1. In addition, it can be confirmed that the surface of the formed bubbles is smooth and free from distortion.

Example 2 shows a result that satisfies all the criteria of the present invention with a foaming rate of 175% and a shrinkage rate of 8.1%, whereas the comparative example 3 has not reached the criterion of shrinkage, and the comparative example 4 has a foaming rate. Has not shown satisfactory results. Through this, it can be expected that the foam of Example 2 has excellent foaming performance and high dimensional stability.

Figure 2 shows a photograph of the foam prepared using the resin composition of Example 2 and Comparative Example 3. It can be seen that the foam according to Example 2 of the figure has clear and even bubbles compared with the foam according to Comparative Example 3. In addition, it can be confirmed that the surface of the formed bubbles is smooth and free from distortion.

Example 3 shows a result that satisfies all the criteria of the present invention with a foaming rate of 184% and a shrinkage rate of 9.8%, whereas in Comparative Example 5, the criterion of shrinkage is not reached, and in Comparative Example 6, Therefore, it is not showing satisfactory results. Through this, it can be expected that the foam of Example 3 also has excellent foaming performance and high dimensional stability.

Figure 3 shows a photograph of the foam produced using the resin composition of Example 3 and Comparative Example 5. It can be seen that the foam according to Example 3 of the drawing has clear and even bubbles compared with the foam according to Comparative Example 5. In addition, it can be confirmed that the surface of the formed bubbles is smooth and free from distortion.

<Example 3, Comparative Examples 7 to 8>

Foams were prepared using the resin compositions of Examples 3 and 7 and 8, and the observed results were analyzed as follows. The foaming rate (%) and shrinkage (%) are shown in Table 5 below.

Example 3 Comparative Example 7 Comparative Example 8 Foaming rate (%) 184 168 186 Red mandarin orange (%) 9.8 8.1 20.2 Measurement method:
(1) Shrinkage: measured after cooling for 24hr at room temperature after demoding.
(2) Foaming ratio: The foaming ratio of the foam was calculated by the ratio of the diagonal length (L) of the mold bottom to the diagonal length (m) of the foam bottom. The percentage of foaming rate was expressed as m / LX 100.

When referring to Table 5 above, Comparative Example 7 does not reach the desired foaming rate of 170%, and in Comparative Example 8, the foaming rate is as high as 186%, but has a shrinkage of less than 15%. It can be seen that the end result has not been reached.

In view of the above results, the present invention is based on the base resin as EVA, and when applied with a chemical inorganic foaming agent and a physical foaming agent, the shrinkage rate is improved by about 50% compared to the case where only the chemical inorganic foaming agent is used, and only the physical foaming agent is used. In this case, it can be confirmed that it is possible to provide the optimal resin composition type and resin composition content that can improve the foaming rate by about 10%.

In addition, the present invention, when the base resin is made of PVC, when applied with a chemical inorganic foaming agent and a physical foaming agent, the shrinkage rate is improved by about 60% compared to the case where only the chemical inorganic foaming agent is used, and the foaming rate is about 8 when the physical foaming agent is used alone. It can be confirmed that it is possible to provide the optimal resin composition type and resin composition content that can be improved by%.

Finally, in the present invention, when the base resin is SBR, and the chemical inorganic foaming agent and the physical foaming agent are applied, the shrinkage rate is improved by about 57% compared to the case where only the chemical inorganic foaming agent is used, and the foaming rate is lower than that when only the physical foaming agent is used. It can be confirmed that it is possible to provide the optimal resin composition type and resin composition content that can be improved by 10%.

The present invention, as well as the improvement of the shrinkage and foaming rate, it can be confirmed that the quality was improved from the prior art in appearance through FIGS.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but those of ordinary skill in the art to which the present invention pertains can be implemented in other specific forms without changing the present invention to its technical spirit or essential features. You will understand that there is. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (13)

Base resin; And
It includes a mixed foaming agent comprising a chemical blowing agent and a physical blowing agent,
The chemical blowing agent is an inorganic blowing agent,
The physical foaming agent is a resin composition comprising a mixed foaming agent having an improved thermal expansion microsphere shrinkage.
According to claim 1,
The base resin is selected from the group consisting of ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC), styrene-butadiene rubber (SBR), and combinations thereof. A resin composition comprising a mixed foaming agent with improved shrinkage.
According to claim 1,
The inorganic foaming agent is a sodium bicarbonate (NaHCO ₃ ) resin composition comprising a mixed foaming agent with improved shrinkage.
According to claim 1,
The thermally expandable microspheres,
An outer shell comprising a thermoplastic resin; And
A resin composition comprising a mixed foaming agent having an improved shrinkage rate that includes a foaming compound encapsulated in the shell.
According to claim 4,
The thermoplastic resin is acrylonitrile (AN), methaacrylonitrile (MAN), methyl methacrylate (Methylmethacrylate, MMA), methacrylic acid (MAA), acrylic acid (Acrylic acid, AA) and combinations thereof.
The foaming compound is a resin comprising a mixed foaming agent with improved shrinkage, which is any one selected from the group consisting of iso-butane, iso-pentane, hexane, and octane. Composition.
According to claim 1,
A resin composition comprising a mixed foaming agent with improved shrinkage, comprising 2 to 5 parts by weight of the mixed foaming agent based on 100 parts by weight of the base resin.
According to claim 1,
The mixed foaming agent is a resin composition comprising a mixed foaming agent having an improved shrinkage rate comprising the chemical foaming agent and the physical foaming agent in a mass ratio of 1: 0.5 to 1: 1.
According to claim 1,
A resin composition comprising a mixed foaming agent with improved shrinkage, further comprising an additive selected from the group consisting of stabilizers, foaming accelerators, fillers, lubricants, crosslinking agents, crosslinking accelerators, plasticizers, and combinations thereof.
According to claim 1,
100 parts by weight of a blend resin of ethylene-vinyl acetate (EVA) or ethylene-vinyl acetate (EVA) and low-density polyethylene (LDPE) as the base resin;
1 to 3 parts by weight of sodium bicarbonate (NaHCO ₃ ) as the chemical blowing agent;
As the physical foaming agent, the outer shell is selected from the group consisting of acrylonitrile (AN), methacryrylonitrile (MAN), and combinations thereof, and the thermal expansion property of the foaming compound is iso-Pentane 1 to 3 parts by weight of microspheres;
Foaming accelerator 1 to 5 parts by weight;
10 to 30 parts by weight of filler;
1 to 5 parts by weight of lubricant; And
A resin composition comprising a mixed foaming agent with improved shrinkage, comprising 0.1 to 2 parts by weight of a crosslinking agent.
According to claim 1,
100 parts by weight of polyvinyl chloride (PVC) as the base resin;
1 to 3 parts by weight of sodium bicarbonate (NaHCO ₃ ) as the chemical blowing agent;
As the physical foaming agent, the outer shell is selected from the group consisting of acrylonitrile (AN), methacryrylonitrile (MAN), and combinations thereof, and the thermal expansion property of the foaming compound is iso-Pentane 1 to 3 parts by weight of microspheres;
Stabilizer 1 to 5 parts by weight;
10 to 50 parts by weight of filler;
1 to 5 parts by weight of lubricant; And
A resin composition comprising a mixed foaming agent with improved shrinkage, comprising 50 to 200 parts by weight of a plasticizer.
According to claim 1,
100 parts by weight of styrene-butadiene rubber (SBR) as the base resin;
1 to 3 parts by weight of sodium bicarbonate (NaHCO ₃ ) as the chemical blowing agent;
As the physical foaming agent, the outer shell is selected from the group consisting of acrylonitrile (AN), methacryrylonitrile (MAN), and combinations thereof, and the thermal expansion property of the foaming compound is iso-Pentane 1 to 3 parts by weight of microspheres;
Foaming accelerator 1 to 5 parts by weight;
1 to 5 parts by weight of lubricant;
1 to 5 parts by weight of a crosslinking agent; And
A resin composition comprising a mixed foaming agent with improved shrinkage, including 0.1 to 2 parts by weight of a crosslinking accelerator.
A foam in which the resin composition of any one of claims 1 to 11 is foamed.
The method of claim 12,
The foam is a midsole of a shoe, an insole of a shoe, an outsole of a shoe, a wallpaper or a mat.

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