KR102410178B1 - Recycled foam composition comprising high content of waste foam scrap, recycled foam produced using same, and method for manufacturing recycled foam - Google Patents

Abstract

The present invention relates to a regenerated foam composition comprising a high content of waste foamed scrap, a regenerated foam prepared using the same, and a method for producing a regenerated foam, and more particularly, to a foam material and 100 parts by weight of the foam material, 5 to 50 parts by weight of pulverized waste foamed scrap, 1 to 5 parts by weight of a foaming agent, 0.5 to 2.0 parts by weight of a crosslinking agent, 0.1 to 1 parts by weight of a crosslinking aid, 5 to 15 parts by weight of a metal oxide, 0.5 to 1 parts by weight of a lubricant, carbonic acid Regeneration comprising 1 to 10 parts by weight of calcium and 0.5 to 3 parts by weight of stearic acid, wherein the waste foamed scrap is pulverized to a size of 10 to 1000 μm to have excellent compatibility and foamability, comprising a high content of waste foamed scrap Disclosed are a foam composition, a regenerated foam produced using the same, and a method for producing the regenerated foam.

Description

Recycled foam composition comprising high content of waste foam scrap, recycled foam produced using same, and method for manufacturing recycled foam }

The present invention relates to a regenerated foam composition comprising a high content of spent foamed scrap, a regenerated foam prepared using the same, and a method for producing the regenerated foam.

EVA is a copolymer made from two different monomer types, ethylene and vinyl acetate. EVA, in a foam state, has rubber-like properties, and is useful in shoes where cushioning action is important, such as a midsole, a sock liner, and a unit sole. In EVA, the relative amount of vinyl acetate to ethylene affects the polymer properties. A higher vinyl acetate content tends to make the polymer softer and more rubbery, while a lower vinyl acetate content tends to make the polymer harder and more crystalline.

EVA foam is prepared by combining ingredients such as EVA polymers, fillers, pigments, crosslinking agents, blowing agents, and processing aids. Optionally, EVA can be blended with other polymer types such as rubber or TPE to increase rubber-like properties. When the components of EVA foam are exposed to high temperature conditions, the blowing agent is activated to release a gas such as carbon dioxide or nitrogen to form a foam. In addition, high temperature conditions activate the crosslinking agent, which reacts with the EVA polymer to form a three-dimensional network. EVA foam compositions are compounded to form a stable foam by carefully balancing the decomposition of peroxide and blowing agent.

EVA foam products are compounded by batch mixing in an ammeter, cooling and dispersal mixing on an open mill, and calendering or granulation to produce a final mixed compound ready for the production of foam.

In the case of foaming materials used for shoe midsoles, etc., olefin resin such as EVA is crosslinked with peroxide and foamed with a chemical foaming agent at the same time. The compound is filled in the mold like cross-linked rubber and cross-linked and foamed. The forming process of the midsole is usually performed by primary foaming (prefoaming) and then secondary molding by heating and compression using its thermoplastic properties.

As such, factors in which EVA resin is widely used as a material for midsoles include mechanical properties including buffering properties, adhesion, processability, foamability, and price. Representative factors influencing the mechanical properties of EVA foam include the expansion ratio and the amount of ethylene and vinyl acetate (VA wt%). The hardness and cushioning properties of the material can be adjusted by changing the magnification or ratio as needed. The hardness of the general EVA foam is about 55 degrees (ASKER-C), and the density is about 0.20 g/cm 3 . In the case of the midsole, a composite design is made in which not only one type of EVA foam but also foam materials of different performance are combined.

As such, EVA foam is widely applied as a shock-absorbing material in the footwear industry due to its low specific gravity, soft feel, and appropriate strength and impact characteristics. By doing so, the volume of waste compared to the same weight is also increased. In relation to this, the process of manufacturing shoes and leather consists of about 20 steps, respectively, and natural leather waste is generated for each process. It had this very big feature. However, due to the growing interest in recycling of resources worldwide, it is necessary to review what is generated from shoe and leather waste in terms of marketability, economic feasibility, and resource efficiency.

In particular, in the case of the midsole, which is a major component of sports shoes, a lot of waste is generated during the manufacturing process. EVA foam is used a lot because of its many advantages (light weight, high whiteness, discoloration resistance, low production cost) compared to PU (poIyurethane) foam. The loss rate is as high as 15%, and the causes of such loss include gate scrap, poor bubble quality, poor contamination, poor size, poor molding, and cutting scrap. Accordingly, currently, although waste EVA scrap generated during the manufacturing process of midsoles for shoes is emerging as a major environmental problem, most of them are incinerated or landfilled.

Therefore, in consideration of recycling in the production stage of the foam, the waste foamed scrap generated in the production process is directly recycled and regenerated at the raw material level. It is required to have characteristics and impact characteristics.

Republic of Korea Patent Publication No. 10-1224536 Republic of Korea Patent Publication No. 10-0893355 Republic of Korea Patent Publication No. 10-1207370

In view of the above technical needs, the present invention aims to provide a regenerated foam composition comprising a high content of waste foamed scrap, using as a raw material the waste foamed scrap generated in the production stage of the foam.

Another technical solution of the present invention is to provide a regenerated foam that is foamed using the regenerated foam composition and that can have appropriate strength characteristics and impact properties without causing bubble defects, and a method for manufacturing the same.

The present invention in order to solve the above technical problem, a foam material,

Based on 100 parts by weight of the foaming material, 5 to 50 parts by weight of crushed waste foamed scrap, 1 to 5 parts by weight of a foaming agent, 0.5 to 2.0 parts by weight of a crosslinking agent, 0.1 to 1 parts by weight of a crosslinking aid, 5 to 15 parts by weight of a metal oxide , 0.5 to 1 parts by weight of lubricant, 1 to 10 parts by weight of calcium carbonate and 0.5 to 3 parts by weight of stearic acid,

The waste foamed scrap is pulverized to a size of 10 to 1000 μm to provide a regenerated foam composition comprising a high content of waste foamed scrap, characterized in that it has excellent compatibility and foamability

In the present invention, the foaming material is characterized in that the foaming temperature or crosslinking temperature is 100 to 200 ℃.

In addition, in the present invention, the foaming material is characterized in that at least one selected from EVA (ethylene-vinyl acetate copolymer), POE (Polyolefin Elastomer), PE (Polyethylene) and TPE (Thermoplastic Elastomer).

In addition, in order to solve the other technical problem, the present invention is prepared using the regenerated foam composition containing the high content of the above-described waste foamed scrap, and the specific gravity is 0.4 or less, characterized in that, including a high content of waste foamed scrap A regenerated foam is provided.

In addition, the present invention comprises the steps of crushing the waste foam scrap in order to solve the other technical problem;

preparing a foam composition comprising the pulverized waste foamed scrap; and

Preparing a regenerated foam including the step of preparing a masterbatch using the foam composition, and foam molding the masterbatch,

The foam composition is a recycled foam composition comprising a high content of waste foamed scrap according to any one of claims 1 to 3,

The prepared foam provides a method for producing a regenerated foam comprising a high content of waste foamed scrap, characterized in that it has a foaming ratio of 130 to 190% based on the length.

According to the present invention, it is possible to manufacture a foam containing a high content of waste foamed scrap by directly recycling the waste foamed scrap generated in the foam production process. Accordingly, it is possible to greatly reduce carbon dioxide emissions and environmental pollution problems caused by incineration, and there is an effect of reducing costs. As described above, the present invention has the effect of directly increasing the greening rate of the industry using the foam by reducing the treatment cost and environmental pollution.

In particular, the present invention has the effect of producing a regenerated foam while including the waste foamed scrap in a high content at the raw material level. Accordingly, in particular, it is possible to secure product competitiveness through cost reduction by making it possible to recycle all waste foamed scrap at a level corresponding to the loss rate of the foamed midsole for shoes, but also has an environmentally sound and sustainable effect.

1 shows an SEM photograph of the pulverized foamed scrap according to the conditions of the pulverization process of the scrap after the foamed scrap is collected in an embodiment of the present invention.
2 is a flowchart showing a manufacturing process of a regenerated foam according to the present invention.
3 is a photograph showing a manufacturing process of a recycled foam including 30 wt% of waste foamed scrap according to an embodiment of the present invention.
4 shows a photograph of a foam according to Example 1 of the present invention.
5 shows a photograph of a foam according to Example 2 of the present invention.
6 shows a photograph of a foam according to Comparative Example 1 of the present invention.
7 shows a photograph of a foam according to Comparative Example 1 of the present invention.
Figure 8 shows the morphology of the foam according to the content of the waste foamed scrap according to an embodiment of the present invention.
9 is a graph showing the change in specific gravity of the foam according to the content of waste foamed scrap according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

The present invention relates to a regenerated foam composition using as a raw material the waste foamed scrap generated in the production stage of the foam, and 5 to 50 parts by weight of the pulverized waste foamed scrap with respect to 100 parts by weight of the foaming material, the foaming material, and the foaming agent 1 ~5 parts by weight, 0.5 to 2.0 parts by weight of a crosslinking agent, 0.1 to 1 parts by weight of a crosslinking aid, 5 to 15 parts by weight of a metal oxide, 0.5 to 1 parts by weight of a lubricant, 1 to 10 parts by weight of calcium carbonate, and 0.5 to 3 parts by weight of stearic acid It relates to a regenerated foam composition comprising a high content of waste foamed scrap.

At this time, the waste foamed scrap is pulverized to a size of 10 to 1000 μm to impart excellent compatibility. In relation to FIG. 1, after collecting the polyolefin foam scraps generated during injection and compression molding, SEM photos of the pulverized foam scraps according to the pulverization process conditions of the scraps are shown. Referring to this, when it exceeds 1 mm, the particles of the pulverized foam are large, and the foaming is not uniform during the final foam production, resulting in a decrease in the foaming rate and a decrease in marketability due to non-uniform appearance.

In general, by using a compatibilizer to compatibilize the blend of the foaming material and the waste foamed scrap, the foamed molded article formed by foaming the foam composition in the presence of the waste foamed scrap thus produces a foamed molded article having suitable aesthetic appearance and physical properties. do. That is, in the case of not using a compatibilizer, in the prior art composition, the amount of waste foamed scrap contained in the composition is limited, and only 30 parts of waste foamed scrap per 100 parts of the foaming material can be included only when the compatibilizer is used.

On the other hand, in the case of the present invention, as described above, as the waste foamed scrap is pulverized to a size of 10 to 1000 μm, the waste foamed scrap is uniformly mixed in the composition, and reacts with the foaming material under high temperature conditions for foam molding. A three-dimensional network is formed. Accordingly, in the present invention, it is possible to improve the stability of the foaming system by crosslinking and compatibilizing effect by the pulverized waste foamed scrap without adding a compatibilizer.

Preferably, the waste foam scrap pulverized to a size of 10 to 1000 μm may be included in an amount of 5 to 50 parts by weight based on 100 parts by weight of the foam material, and more preferably 15 parts by weight or more. Thus, by including 15 parts by weight or more of waste foamed scrap, which is generated at a high loss rate of 15% or more during foam manufacturing, the entire amount of waste foamed scrap generated in the production process can be directly recycled and recycled as raw materials, thereby realizing zero waste. Rather, it is possible to produce an entirely regenerated foam without the use of additives such as compatibilizers, thereby composing an eco-friendly process.

At this time, the high temperature condition for the foam molding is 100 to 200 ℃, the foam material is characterized in that the foaming temperature or crosslinking temperature is 100 to 200 ℃.

Preferably, the foam material can be processed in the same way as thermoplastic plastic during molding, and is a thermoplastic elastomer having rubber properties at room temperature, EVA (ethylene-vinyl acetate copolymer), POE (Polyolefin Elastomer), One or more types may be selected from polyethylene (PE) and thermoplastic elastomer (TPE). do. More preferably, EVA may be selected so that the foam material has a low specific gravity, a soft feel, and appropriate strength characteristics and impact characteristics.

In addition, in the regenerated foam composition of the present invention, the foaming agent is not particularly limited, but is preferably used in an amount of 1 to 5 parts by weight based on 100 parts by weight of the foaming material. At this time, if the amount of the foaming agent used is less than 1 part by weight, the density of the foam is high and there is no foaming effect. Therefore, it cannot be applied for industrial purposes.

Examples of such a blowing agent include azodicarbonamide-based, diazominoexobenzene-based, n,n'-dinitrosopentamethylenetetraamine-based, p-toluenesulfonylhydrazide-based, p,p’-oxybis( One or more types may be selected from the group consisting of benzenesulfonylhydrazide) or benzenesulfonylhydrazide.

In addition, since the present invention basically uses a thermoplastic elastomer as a foaming material, crosslinking to improve physical properties is unnecessary, but the use of a crosslinking agent is essential as a component that plays a role in providing high-temperature viscoelasticity of the resin to collect the decomposed gas generated from the foaming agent. . Sulfur, a sulfur donor, and organic peroxide are all possible as the crosslinking agent, but in the present invention, it is particularly preferable to use an organic peroxide having a one-minute half-life temperature of 150 to 180° C. than when other crosslinking agents are used in the control of durability and foaming properties, etc. If the one-minute half-life temperature is less than 150 ℃, there is a risk of premature decomposition in the compound manufacturing process, and if it is 180 ℃ or more, there is a problem that the time required to manufacture the foam by a press is long, resulting in a decrease in productivity.

The organic peroxide crosslinking agent is not particularly limited, but 0.5 to 2.0 parts by weight is used based on 100 parts by weight of the base material. If the product is more than 2.0 parts by weight, the foaming gas pressure is increased due to an increase in the crosslinking density due to excessive crosslinking, which causes the foam to burst. there is a risk of becoming

Examples of such an organic peroxide crosslinking agent include t-butylperoxyisopropylcarbonate, t-butylperoxylaurylate, t-butylperoxyacetate, di-t-butylperoxyphthaletide, t-dibutylperoxymaleic acid , cyclohexanone peroxide, t-butylcumylperoside, t-butylhydroperoxide, t-butylperoxybenzoate, ticumylperoxide, 1,3-bis(t-butylperoxyisopropyl)benzene, methylethyl Ketone peroxide, 2,5-dimethyl-2,5-di (benzoyloxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butyl peroxide, 2 ,5-Dimethyl-2,5-(t-butylperoxy)-3-hexane, n-butyl-4,4-bis(t-butylperoxy)valerate and a,a'-bis(t-butyl One or more of peroxy) isopropylbenzenes may be selected and used.

In addition, in the present invention, in order to obtain an appropriate crosslinking structure for shortening the molding time and improving durability during peroxide crosslinking, it is preferable to use 0.1 to 1 parts by weight of the crosslinking aid based on 100 parts by weight of the foaming material as the crosslinking agent, and the amount used is 0.1 parts by weight. When the amount is less than 1 part, there is a fear that there is little effect of promoting crosslinking.

Examples of the crosslinking aid include divinylbenzene, triaryl cyanurate, triaryl isocyanurate, ethylene glycol dimethacrylate, diethyl glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate One or more of acrylate, aryl methacrylate, vinyl butyrate and vinyl stearate may be selected and used.

In addition, in the regenerated foam composition of the present invention, in addition to the foam material, waste foamed scrap, foaming agent, crosslinking agent, and crosslinking aid, it is possible to use metal oxides and stearic acid as fillers and lubricants to stabilize crosslinking and improve foaming properties.

Zinc oxide is used as the metal oxide to promote crosslinking, and it is preferable to add 5 to 15 parts by weight based on 100 parts by weight of the foam material. If the amount of zinc oxide used is out of the above range, there is a fear that problems of non-crosslinking or over-crosslinking may occur. And, as for stearic acid to induce flat crosslinking, it is preferable to use 0.5 to 3 parts by weight based on 100 parts by weight of the foaming material. Blooming may occur.

In addition, the filler is used to improve shock absorption, and at least one selected from calcium carbonate and magnesium carbonate. In addition to degradation, it is difficult to control the foaming process, making it impossible to produce a normal elastic foam.

On the other hand, the content of each foam additive is a range already known for foam production, but is not limited to the above range and may be variably applied depending on the type of foam and the usage environment.

In another aspect, according to the present invention, it is possible to provide a recycled foam containing a high content of waste foamed scrap by foaming using the recycled foam composition. At this time, preferably, even if the high content of the above-mentioned waste foamed scrap is included, the crosslinking and compatibility are improved by including the waste foamed scrap pulverized to a size of 10 to 1000 μm as described above, so that it has sufficient elasticity and mechanical properties as a foam. It is characterized in that it can exhibit physical properties and has a specific gravity of 0.4 or less. As an embodiment, when using an EVA foam material, the specific gravity is changed by controlling the foaming ratio or the amount of ethylene and vinyl acetate (VA wt%) to adjust the hardness and warmth of the material, so in a preferred embodiment of the present invention According to the results, it was confirmed that the specific gravity was 0.15 or 0.25, which is 0.4 or less, so as to have sufficient physical properties as a foam. That is, considering that the density of a typical EVA foam is about 0.20 g/cm 3 , that is, the regenerated foam according to the present invention can exhibit excellent foaming properties even with a high content of waste foamed scrap.

2 is a flowchart showing a manufacturing process of a regenerated foam according to the present invention. Referring to this, in another aspect, the present invention relates to a method for producing a regenerated foam comprising a high content of waste foamed scrap, comprising the steps of: pulverizing the waste foamed scrap; preparing a foam composition comprising the pulverized waste foamed scrap; and preparing a masterbatch using the foam composition, and foam-molding the masterbatch to prepare a regenerated foam.

In addition, Figure 3 is a photograph showing the manufacturing process of the foam containing 30 parts by weight of the waste foamed scrap. As described above, the present invention includes a high content of the waste foamed scrap without including a compatibilizer, etc. to manufacture a recycled foam It is characterized by being able to do it. Accordingly, it is possible to include the waste foamed scrap, which is essentially generated during the production of foam, at the level of the raw material to be regenerated.

At this time, the manufactured foam is characterized in that it has an expansion ratio of 130 to 190% based on the length. As described above, by adjusting the foaming ratio, the hardness and buffering properties of the foam can be adjusted. When the foaming ratio is low, the foaming performance cannot be satisfied because the cell characteristics of the cross section are poor and the specific gravity is high.

Hereinafter, the present invention will be described in detail with reference to examples of the present invention.

<Examples 1-2 and Comparative Examples 1-2>

Foam scrap was collected (self-collection) and pulverized to a size of 10-1000 μm using a self-made grinding device to prepare a foam scrap. Next, after filling the compound in the mold, pressurized foam molding at 170 ° C. for 10 minutes, and demolding to prepare a foam. At this time, the compound for foaming is 10 to 90 parts by weight of foamed scrap based on 100 parts by weight of EVA, 10 parts by weight of metal oxide (zinc oxide), 1.5 parts by weight of crosslinking agent (dicumyl peroxide), 4 parts by weight of foaming agent (azodicarbonamide) Parts by weight, stearic acid was prepared by mixing 0.7 parts by weight of a filler (calcium carbonate) 1.0 parts by weight, an accelerator (triallyl cyanurate), and 0.1 parts by weight in common.

Specific mixing ratios are shown in Table 1 below, and the foam was molded under the same conditions.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 EVA 100 100 100 100 play scrap 10 50 70 90 blowing agent, additive Crosslinking agent, 1.0, azodicarbonamide 4, metal oxide 10, lubricant 0.7, calcium carbonate 1.0, triallyl cyanurate 0.1

The foaming characteristics and specific gravity of the cross section were evaluated, and the results are shown in Table 2 and FIGS. 4 to 7 below. In the case of specific gravity, based on the KS M 6519 standard, it is a value obtained by taking the average of three measurements except for the maximum and minimum values after 5 measurements.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Firing ratio (%) 180% 140% 130 125 importance 0.15
(Good) 0.25
(Good) 0.41
(error) 0.52
(error)

As shown in Table 2, in Comparative Examples 1 and 2 containing 70 and 90 parts by weight of recycled scrap, respectively, the foaming ratio of the foam was 130 or less, and when the recycled scrap was included in 50 parts by weight or less, the foam It can be seen that the foaming ratio is 140% or more, showing excellent foaming properties.

In addition, Figures 4 to 7 show the cross-sectional cell uniformity evaluation results for the foams of Examples 1 and 2 and Comparative Examples 1 and 2, respectively, in which Examples 1 and 2 were small and uniform even though they contained recycled scrap. It can be confirmed that the bubble characteristics, on the other hand, Comparative Example 1 containing 70 parts by weight and Comparative Example 2 containing 90 parts by weight can be confirmed that the bubbles are non-uniform or poor bubble formation.

In addition, referring to Table 1, as a result of measuring the specific gravity of the foam, Examples 1 and 2 showed good properties with specific gravity of 0.20 and 0.25, respectively, but Comparative Example 1 and Comparative Example 2 had high specific gravity of 0.41 and 0.52, respectively. As a result, it can be seen that the use of the foam as a foam is poor because it does not satisfy the requirements of the foam, which is important in light-weight shock absorption.

In addition, the surface (skin) and the cross-section of the foam morphology according to the content of EVA-based and TPE-based waste foamed scrap are shown in FIG. 8, and the specific gravity change is shown in FIG. 9 as a graph. As can be seen in FIG. 8 , even when 20 phr was included, similar foaming was performed when the regenerated foam was not included, and uniform and good foaming properties were exhibited. Referring to FIG. 9 , it was confirmed that the specific gravity appeared up to 0.20 level even in the change of specific gravity, and thus it was confirmed that the foaming ratio was excellent and the foaming morphology was also good.

As described above, according to the present invention, it can be confirmed that, despite the high content of the spent foamed scrap, it exhibits compatibility without using a compatibilizer or the like, and exhibits excellent foamability, thereby sufficiently exhibiting the physical properties of the foam. Accordingly, it is possible to directly recycle the waste foamed scrap generated during the foam production process to manufacture a foam containing a high content of waste foamed scrap, thereby greatly reducing carbon dioxide emissions and environmental pollution caused by incineration, and reducing costs. It is expected that it will be possible to directly increase the greening rate of the industry using the foam by reducing the treatment cost and environmental pollution.

Claims (5)

In the recycled foam composition comprising the waste foamed scrap,
foam material,
Based on 100 parts by weight of the foaming material, 5 to 50 parts by weight of crushed waste foamed scrap, 1 to 5 parts by weight of a foaming agent, 0.5 to 2.0 parts by weight of a crosslinking agent, 0.1 to 1 parts by weight of a crosslinking aid, 5 to 15 parts by weight of a metal oxide , 0.5 to 1 parts by weight of lubricant, 1 to 10 parts by weight of calcium carbonate and 0.5 to 3 parts by weight of stearic acid,
The waste foamed scrap is pulverized to a size of 10 to 1000 μm and has excellent compatibility and foaming properties.
The foam material includes at least one of EVA (ethylene-vinyl acetate copolymer) or TPE (Thermoplastic Elastomer),
The specific gravity of the regenerated foam composition comprising the waste foamed scrap is 0.15 to 0.25, and has a foaming ratio of 140 to 180% based on the length, and is used for a shoe midsole. . According to claim 1,
The foaming material is a regenerated foam composition comprising a waste foamed scrap, characterized in that the foaming temperature or the crosslinking temperature is 100 to 200 ℃. delete It is manufactured using the regenerated foam composition comprising the waste foamed scrap according to any one of claims 1 to 2, has a specific gravity of 0.15 to 0.25 and a foaming ratio of 140 to 180% based on the length, but is used for midsole shoes Regenerated foam comprising a waste foamed scrap, characterized in that used as. crushing the waste foamed scrap;
preparing a foam composition comprising the pulverized waste foamed scrap; and
Preparing a regenerated foam, including preparing a masterbatch using the foam composition, and foam molding the masterbatch,
The foam composition is a recycled foam composition comprising the waste foamed scrap according to any one of claims 1 to 2,
The specific gravity of the regenerated foam composition comprising the waste foamed scrap is 0.15 to 0.25, and has a foaming ratio of 140 to 180% based on the length, and is used for a shoe midsole. .

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