KR20240107730A - A method of manufacturing a foam using a recycled foam - Google Patents

Abstract

The present invention relates to a method of manufacturing foam using waste foam. The manufacturing method includes providing the waste foam to pass through a gap between a pair of rollers rotating in opposite directions to obtain pulverized waste foam; manufacturing the pulverized material into a sheet; crushing the sheet to obtain waste scrap; Preparing raw materials including the waste scrap, a resin containing ethylene vinyl acetate (EVA), a crosslinking agent, and a foaming agent; And it may include the step of foaming the raw materials to obtain a foam.

Description

Method of manufacturing foam using waste foam {A METHOD OF MANUFACTURING A FOAM USING A RECYCLED FOAM}

The present invention relates to a method of manufacturing foam using waste foam.

Polyolefin copolymers, such as ethylene vinyl acetate (EVA), are used to manufacture articles in a variety of fields, including films, molded products, and foams.

Ethylene vinyl acetate (EVA) has properties such as good processability, low production cost, flexibility, and low density, but its physical and chemical properties such as stickiness and deformability can cause difficulties during processing.

Foams containing ethylene vinyl acetate (EVA) as the main ingredient are widely used in shoe midsoles and mats.

In the past, due to a lack of recycling technology for foams containing electron beam cross-linked ethylene vinyl acetate (EVA) as a main ingredient, discarded foams were incinerated or shredded. Simple disposal and shredding of foam causes problems with environmental pollution and increases costs due to increased disposal costs.

The purpose of the present invention is to provide a method for producing a foam using a foam containing electron beam crosslinked ethylene vinyl acetate (EVA) as a main component.

The purpose of the present invention is to provide a method for manufacturing foam that can increase the content of waste foam.

The object of the present invention is not limited to the objects mentioned above. The object of the present invention will become clearer from the following description and may be realized by means and combinations thereof as set forth in the claims.

A method for manufacturing foam according to an embodiment of the present invention includes the steps of providing waste foam to pass through a gap between a pair of rollers rotating in opposite directions to obtain pulverized waste foam; manufacturing the pulverized material into a sheet; crushing the sheet to obtain waste scrap; Preparing raw materials including the waste scrap, resin, crosslinking agent, and foaming agent; And it may include the step of foaming the raw materials to obtain a foam.

The resin may include at least one selected from the group consisting of ethylene vinyl acetate (EVA), polyethylene (PE), polyvinyl chloride (PVC), and combinations thereof.

The waste foam may be electron beam crosslinked.

The waste foam may include ethylene vinyl acetate (EVA).

The pair of rollers may rotate at a speed of 10 rpm to 15 rpm.

The size of the gap may be 9mm to 15mm.

The pair of rollers is accommodated in a chamber, and the step of obtaining pulverized waste foam includes pulverizing the waste foam into the gap between the pair of rollers while providing steam at 80° C. to 100° C. in the chamber. It may be provided to pass.

The diameter of the waste scrap may be 7mm to 10mm.

The raw material may include 10% to 50% by weight of the waste scrap and 50% to 90% by weight of the resin, based on the combined weight of the waste scrap and the resin.

The raw material may include 0.5 to 0.95 parts by weight of the crosslinking agent and 20 to 30 parts by weight of the foaming agent, based on 100 parts by weight of the waste scrap and resin.

The crosslinking agent may include 1,3-bis(t-butylperoxyisopropyl)benzene.

The foaming agent is a hydrazide-based foaming agent; and physical blowing agents; and at least one of the above, and the physical foaming agent may include thermally expandable microspheres.

The hydrazide-based blowing agent may include at least one selected from the group consisting of p,p'-oxybis(benzenesulfonylhydrazide), p-toluenesulfonylhydrazide, benzenesulfonylhydrazide, and combinations thereof. .

The heat-expandable microspheres include a shell containing a thermoplastic resin; and a foaming compound contained in the outer shell, wherein the thermoplastic resin includes acrylonitrile (AN), methacrylonitrile (MAN), methyl methacrylate (MMA), and methacrylic acid. (Methacrylicacid, MAA), acrylic acid (AA), and combinations thereof, and the foaming compound may include hydrocarbon.

The step of obtaining a foam by foaming the raw material may include turning the raw material into a seedbed and then foaming the seedbed by pressing the seedbed.

The mother plate can be placed into a mold and then pressed at 150°C to 200°C for 10 to 30 minutes to foam.

The manufacturing method may further include aging the foam in an oven at 40°C to 60°C for 10 to 30 minutes.

According to the present invention, it is possible to obtain a method of producing a foam using a foam containing electron beam crosslinked ethylene vinyl acetate (EVA) as a main component.

According to the present invention, a method for manufacturing foam that can increase the content of waste foam can be obtained.

According to the present invention, it is possible to obtain a foam manufacturing method that can increase the dispersibility of waste scrap manufactured from waste foam.

According to the present invention, incineration of waste foam can be avoided, thereby reducing the generation of carbon dioxide.

According to the present invention, even when used foam is used, a foam showing substantially the same or similar mechanical properties as when using a new resin can be obtained.

The effects of the present invention are not limited to the effects mentioned above. The effects of the present invention should be understood to include all effects that can be inferred from the following description.

Figure 1 shows a method for producing foam according to the present invention.
Figure 2 schematically shows a device for grinding waste foam according to the present invention.
Figure 3 shows the gap between a pair of rollers rotating in opposite directions.

The above objects, other objects, features and advantages of the present invention will be easily understood through the following preferred embodiments related to the attached 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 so that the disclosed content will be thorough and complete and so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art.

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

In this specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof. Additionally, when a part of a layer, membrane, region, plate, etc. is said to be “on” another part, this includes not only being “directly above” the other part, but also cases where there is another part in between. Conversely, when a part of a layer, membrane, region, plate, etc. is said to be "underneath" another part, this includes not only being "immediately below" the other part, but also cases where there is another part in between.

Unless otherwise specified, all numbers, values, and/or expressions used herein expressing quantities of components, reaction conditions, polymer compositions, and formulations are intended to represent, among other things, how such numbers inherently occur in obtaining such values. Since they are approximations reflecting the various uncertainties of measurement, they should be understood in all cases as being qualified by the term "approximately". Additionally, where a numerical range is disclosed herein, such range is continuous and, unless otherwise indicated, includes all values from the minimum to the maximum of such range inclusively. Furthermore, when such range refers to an integer, all integers from the minimum value up to and including the maximum value are included, unless otherwise indicated.

Figure 1 shows a method for producing foam according to the present invention. Referring to this, the manufacturing method includes the steps of obtaining pulverized waste foam (S10), manufacturing the pulverized product into a sheet (S20), and pulverizing the sheet to obtain waste scrap (Scarp) (S30). , preparing raw materials including the waste scrap, resin, etc. (S40), and foaming the raw materials to obtain a foam (S50).

The source of the waste foam is not particularly limited. For example, the waste foam may be foam discarded in the process of manufacturing mats and shoe midsoles.

The waste foam may contain ethylene vinyl acetate (EVA). For example, the waste foam may contain more than 50% by weight, more than 60% by weight, more than 70% by weight, more than 80% by weight, or more than 90% by weight of ethylene vinyl acetate (EVA).

The waste foam may be electron beam crosslinked. Specifically, the waste foam may be a waste material of foam manufactured by foaming an electron beam crosslinked motherboard.

The present invention is characterized in that the waste foam is crushed by a physical method to remove nitrogen gas therein and then recycled. If the nitrogen gas inside the waste foam is sufficiently removed, the volume of the waste foam is reduced by about 30% to 50%, so that dispersibility can be improved when mixed with new resin. Therefore, even if the content of the waste foam is increased, it is possible to prevent the physical properties of the final foam from deteriorating.

Specifically, pulverized waste foam can be obtained by providing the waste foam to pass through a gap between a pair of rollers rotating in opposite directions (S10).

Figure 2 schematically shows a crushing device for the waste foam. The pulverizing device is connected to a pair of rollers (A, A'), a chamber (B) accommodating the pair of rollers (A, A'), and one roller (A') to manufacture the pulverized material into a sheet. It may include a scraper roller (C). Figure 3 shows the gap A'' between a pair of rollers A and A' rotating in opposite directions.

The waste foam 10 may be pulverized by pressure generated in the gap A'' between the pair of rollers A and A'.

The pair of rollers (A, A') may rotate at a speed of 10 rpm to 15 rpm. Additionally, the pair of rollers (A, A') may rotate at different speeds within the above numerical range. Shear forces occur in the gap A'' between a pair of rollers A and A' rotating at different speeds, so the waste foam 10 can be pulverized more effectively. Specifically, based on FIG. 2, it may be desirable for the rotation speed of the roller (B) on the right side to be faster than the roller (A) on the left side.

Additionally, the size of the gap A'' may be 9 mm to 15 mm. The narrower the gap (A''), the stronger pressure can be applied to the waste foam 10, but since this may be disadvantageous in terms of fairness, the size of the gap (A'') is adjusted within the above numerical range. This may be desirable.

The step of obtaining the pulverized material 20 of the waste foam 10 is to place the waste foam 10 on a pair of rollers (A, It may be provided to pass through the gap (A'') between A'). Increasing the temperature can be advantageous in not only pulverizing the waste foam 10 more effectively but also in removing nitrogen gas therein.

The pulverized material 20 obtained in the same manner as above can be manufactured into a sheet 30 (S30).

As described above, the grinding device may be a three roll mill device. That is, the grinding device may further include a scraper roll (C) connected to a pair of rollers. Based on FIG. 2, the pulverized material 20 that adheres to the surface of the middle roll (A) passes between the roll (A) and the scraper roll (C) and may become a sheet 30.

However, the method of manufacturing the sheet 30 is not limited to this, and a separate device that can manufacture the sheet after separately collecting the pulverized material 20 may be used.

Thereafter, the sheet can be pulverized to obtain waste scrap (S30). The method of pulverizing the sheet is not particularly limited, and for example, the sheet can be pulverized using a cutting device equipped with a blade.

At this time, the sheet may be pulverized so that the diameter of the waste scrap is 7 mm to 10 mm. For example, waste scrap can be obtained by passing the result of pulverizing the sheet through a strainer with a mesh spacing of 7 mm to 10 mm.

Raw materials can be prepared by mixing the waste scrap prepared as above with resin, crosslinking agent, foaming agent, additives, etc. (S40).

The resin may include at least one selected from the group consisting of ethylene vinyl acetate (EVA), polyethylene (PE), polyvinyl chloride (PVC), and combinations thereof. Preferably, the resin may include ethylene vinyl acetate (EVA). The resin may contain 90% by weight or more, 95% by weight or more, 99% by weight or more, and preferably 100% by weight of ethylene vinyl acetate (EVA) based on the total weight.

The ethylene vinyl acetate (EVA) may contain 30% by weight or less of vinyl acetate based on the total weight. The lower limit of the vinyl acetate content is not particularly limited, and may be, for example, 1% by weight or more, 5% by weight or more, 10% by weight or more, or 20% by weight or more.

Ethylene vinyl acetate (EVA) is a type of polyethylene-based resin. Compared to other types of polyethylene-based resins such as low density polyethylene (LDPE), ethylene vinyl acetate (EVA) is flexible and elastic at room temperature and exhibits properties similar to rubber.

The raw material may include 10% to 50% by weight of the waste scrap and 50% to 90% by weight of the resin, based on the combined weight of the waste scrap and the resin. Since the waste foam is physically pulverized using a pulverizing device as shown in FIG. 2 to sufficiently remove nitrogen gas therein, the volume of the waste scrap is reduced by about 30% to 50% compared to general pulverized material. Therefore, since the waste scrap is well mixed with the resin, its content can be increased up to 50% by weight.

The crosslinking agent may include 1,3-bis(t-butylperoxyisopropyl)benzene. If the content of waste scrap increases, overcrosslinking of the final foam may occur. Accordingly, the present invention is characterized by preventing the above problems from occurring by adjusting the content of the cross-linking agent according to the content of the waste scrap. As the content of the waste scrap increases, the content of the crosslinking agent can be reduced to prevent overcrosslinking of the foam. The content of the cross-linking agent will be described later.

The foaming agent may include at least one of a hydrazide-based foaming agent and a physical foaming agent.

The hydrazide-based blowing agent may include at least one selected from the group consisting of p,p'-oxybis(benzenesulfonylhydrazide), p-toluenesulfonylhydrazide, benzenesulfonylhydrazide, and combinations thereof. .

The hydrazide-based foaming agent is environmentally friendly because it does not emit harmful components such as ammonia and formamide during decomposition.

The physical foaming agent may include thermally expandable microspheres. The heat-expandable microspheres may include a shell containing a thermoplastic resin and a foaming compound contained in the shell.

The thermoplastic resin includes acrylonitrile (AN), methacrylonitrile (MAN), methyl methacrylate (MMA), methacrylicacid (MAA), and acrylic acid (Acrylic acid, AA) and combinations thereof.

The foaming compound may include hydrocarbon.

The foaming agent may include a hydrazide-based foaming agent and a physical foaming agent in a mass ratio of 1:0.1 to 0.3.

The raw material may include 0.5 to 0.95 parts by weight of the crosslinking agent and 20 to 30 parts by weight of the foaming agent, based on 100 parts by weight of the waste scrap and resin.

As the content of the waste scrap increases among 100 parts by weight of the waste scrap and the resin, the content of the cross-linking agent can be reduced within the above range.

Specifically, when the content of the waste scrap is 10% to 20% by weight based on 100 parts by weight of the waste scrap and the resin, the raw material may include 0.8 to 0.95 parts by weight of the crosslinking agent.

In addition, when the content of the waste scrap is 20% to 30% by weight based on 100 parts by weight of the waste scrap and the resin, the raw material may include 0.7 to 0.8 parts by weight of the crosslinking agent.

In addition, when the content of the waste scrap is 30% to 50% by weight based on 100 parts by weight of the waste scrap and the resin, the raw material may include 0.5 to 0.7 parts by weight of the crosslinking agent.

The raw materials may further include additives such as pigments, processing aids, and fillers. The types of additives are not particularly limited and may include those commonly used in the technical field, considering the use of the foam, etc.

Foam can be obtained by foaming the raw materials (S50). Specifically, after making the raw material into a seedbed, the seedbed can be placed into a mold and pressed at 150°C to 200°C for 10 to 30 minutes to foam.

The manufacturing method may further include the step of aging the foam prepared as above in an oven at 40°C to 60°C for 10 to 30 minutes.

Hereinafter, the present invention will be described in more detail through specific examples. However, these examples are for illustrating the present invention and the scope of the present invention is not limited thereto.

Examples 1 to 4

A waste foam containing ethylene vinyl acetate (EVA) and crosslinked with electron beams was prepared. A pair of rollers rotating in opposite directions was prepared as a grinding device. A pair of rollers with a diameter of about 8 inches were installed with a gap of about 9 mm to 15 mm and rotated at about 10 rpm to 15 rpm. The waste foam was provided in the gap between the pair of rollers to obtain pulverized material. At this time, steam was supplied to the chamber so that the waste foam was pulverized at about 80°C to 100°C.

After producing the pulverized material into a sheet, the sheet was pulverized in a grinder equipped with a filter having a mesh spacing of about 7 mm to 10 mm to obtain waste scrap.

The waste scrap and new ethylene vinyl acetate (EVA) were mixed in the amounts shown in Table 1 below, and then the crosslinking agent, foaming agent, and additives were mixed in the amounts shown in Table 1 to prepare raw materials. 1,3-bis(t-butylperoxyisopropyl)benzene (BIBP) was used as the crosslinking agent, and a hydrazide-based blowing agent and a physical blowing agent were used as the blowing agent. p,p'-oxybis(benzenesulfonylhydrazide) was used as the hydrazide-based blowing agent, and thermally expandable microspheres (T _s 165°C, T _m 195°C) were used as the physical blowing agent.

After making the raw material into a seedbed, the seedbed was placed in a mold measuring 10cm

The foam was placed in an oven at about 50°C, rested for about 15 minutes, and then cooled to room temperature.

Comparative Example 1

Foam was manufactured in the same manner as Examples 1 to 4, except that only new ethylene vinyl acetate (EVA) was used instead of the waste scrap as the raw material. The raw material components of Comparative Example 1 are summarized in Table 2 below.

Comparative Examples 2 to 5

Instead of pulverizing the waste foam with a pair of rollers, waste scrap obtained by pulverizing it with a crusher equipped with a strainer with a mesh spacing of about 7 mm to 10 mm was used. Other than that, the foam was manufactured in the same manner as Examples 1 to 4 above. The raw material components of Comparative Examples 2 to 5 are summarized in Table 2 below.

ingredient Example 1 Example 2 Example 3 Example 4 New EVA [weight%] 90 80 70 50 Waste scrap [% by weight] 10 20 30 50 Amazing [part by weight] 5 5 5 5 ZnO [part by weight] 2 2 2 2 TiO ₂ [part by weight] 4.8 4.8 4.8 4.8 Pigment [part by weight] 0.2 0.2 0.2 0.2 Stearic acid [parts by weight] 0.31 0.31 0.31 0.31 Crosslinking agent [part by weight] 0.95 0.8 0.7 0.58 Foaming agent [part by weight] 24 24 24 24

* The weight part in Table 1 is based on 100 parts by weight including new EVA and waste scrap.

ingredient Comparative Example 1 Comparative example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 New EVA [weight%] 100 90 80 70 50 Waste scrap [% by weight] - 10 20 30 50 Amazing [part by weight] 5 5 5 5 5 ZnO [part by weight] 2 2 2 2 2 TiO ₂ [part by weight] 4.8 4.8 4.8 4.8 4.8 Pigment [part by weight] 0.2 0.2 0.2 0.2 0.2 Stearic acid [parts by weight] 0.31 0.31 0.31 0.31 0.31 Crosslinking agent [part by weight] 0.95 0.95 0.8 0.7 0.58 Foaming agent [part by weight] 24 24 24 24 24

* In Table 2, the weight part is based on 100 parts by weight including new EVA and waste scrap.

* Waste scrap in Table 2 is not pulverized by a pair of rollers.

The physical properties of the foams according to Examples 1 to 4 and Comparative Examples 1 to 5 were measured and shown in Tables 3 and 4 below.

item Example 1 Example 2 Example 3 Example 4 Expansion ratio [%] 185 185 185 185 Density [g/cc] 0.117 0.117 0.117 0.117 Hardness [Type C] 34 34 34 34 Tensile strength [kg/cm ² ] 13.3 12.8 12.5 11.8 Elongation [%] 190 200 220 220 Tear strength [Kg/cm] 4.90 4.85 4.66 4.38 Split tear [Kg/cm] 1.37 1.33 1.30 1.28 Compression set [%] 74.04 72.75 70.57 70.10 Skin pin hole [Number, 10cmX10cm] 0~1 1~2 1~2 1~2

item Comparative Example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative Example 5 Expansion ratio [%] 186 185 185 185 185 Density [g/cc] 0.117 0.117 0.116 0.116 0.116 Hardness [Type C] 34 34 34 34 34 Tensile strength [kg/cm ² ] 13.4 9.5 8.4 7.9 6.3 Elongation [%] 230 130 140 140 150 Tear strength [Kg/cm] 4.93 4.02 3.15 3.0 2.54 Split tear [Kg/cm] 1.39 0.96 0.82 0.77 0.62 Compression set [%] 76.91 80.44 84.34 85.6 87.5 Skin pin hole [Number, 10cmX10cm] 0 10 15 20 25

Referring to Tables 3 and 4, the foams of Examples 1 to 4 according to the present invention show physical properties at the same or similar level compared to Comparative Example 1 using only new materials. On the other hand, the foams of Comparative Examples 2 to 4 that were not pulverized had poor physical properties such as elongation, tear resistance, compression set, and surface quality compared to the Examples. can be seen.

As the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the above-described embodiments, and various modifications and modifications by those skilled in the art using the basic concept of the present invention as defined in the following patent claims are made. Improved forms are also included in the scope of the present invention.

10: Waste foam 20: Ground material 30: sheet

Claims (16)

Obtaining pulverized waste foam by providing the waste foam to pass through a gap between a pair of rollers rotating in opposite directions;
manufacturing the pulverized material into a sheet;
crushing the sheet to obtain waste scrap;
Preparing raw materials including the waste scrap, resin, crosslinking agent, and foaming agent; and
Comprising the step of foaming the raw materials to obtain a foam,
The resin is a foam using waste foam containing at least one selected from the group consisting of ethylene vinyl acetate (EVA), polyethylene (PE), polyvinyl chloride (PVC), and combinations thereof. Manufacturing method. According to paragraph 1,
A method of manufacturing a foam using waste foam, wherein the waste foam is cross-linked with electron beams. According to paragraph 1,
A method of producing a foam using waste foam, wherein the waste foam contains ethylene vinyl acetate (EVA). According to paragraph 1,
A method of manufacturing a foam using waste foam, wherein the pair of rollers rotates at a speed of 10 rpm to 15 rpm. According to paragraph 1,
A method of producing a foam using waste foam wherein the size of the gap is 9 mm to 15 mm. According to paragraph 1,
The pair of rollers is accommodated in a chamber,
The step of obtaining pulverized waste foam includes providing the waste foam to pass through a gap between a pair of rollers while providing steam at 80°C to 100°C in the chamber. Method for manufacturing foam. According to paragraph 1,
A method of producing a foam using waste foam where the diameter of the waste scrap is 7mm to 10mm. According to paragraph 1,
The raw materials are
Based on the combined weight of the above waste scrap and resin
10% to 50% by weight of the waste scrap and
A method of producing a foam using waste foam containing 50% to 90% by weight of the resin. According to paragraph 1,
The raw materials are
Based on 100 parts by weight of the above waste scrap and resin combined
0.5 to 0.95 parts by weight of the cross-linking agent and
A method of producing a foam using waste foam containing 20 to 30 parts by weight of the foaming agent. According to paragraph 1,
The crosslinking agent is a method of producing a foam using waste foam containing 1,3-bis(t-butylperoxyisopropyl)benzene. According to paragraph 1,
The foaming agent is a hydrazide-based foaming agent; and physical blowing agents; A method of producing a foam using waste foam, wherein the physical foaming agent includes thermally expandable microspheres. According to clause 11,
The hydrazide-based foaming agent is a waste foam containing at least one selected from the group consisting of p,p'-oxybis(benzenesulfonylhydrazide), p-toluenesulfonylhydrazide, benzenesulfonylhydrazide, and combinations thereof. Method for manufacturing foam using foam. According to clause 11,
The heat expandable microspheres are
Outer shell containing thermoplastic resin; and
Comprising a foaming compound contained in the shell,
The thermoplastic resin includes acrylonitrile (AN), methacrylonitrile (MAN), methyl methacrylate (MMA), methacrylicacid (MAA), and acrylic acid (Acrylic acid, AA) and combinations thereof,
The foaming compound is a method of producing a foam using waste foam containing hydrocarbon. According to paragraph 1,
The step of obtaining a foam by foaming the raw material is to make the raw material into a seedbed and then press the seedbed to foam the foam. According to clause 14,
A method of manufacturing a foam using waste foam, wherein the mother plate is placed in a mold and then foamed by pressing at 150°C to 200°C for 10 to 30 minutes. According to paragraph 1,
A method of producing a foam using waste foam, further comprising aging the foam in an oven at 40°C to 60°C for 10 to 30 minutes.