WO2018124385A1 - Polyurethane midsole for shoe and manufacturing method therefor - Google Patents

Abstract

Disclosed are a midsole for a shoe and a manufacturing method therefor, the midsole, as an alternative to conventional integrally-formed polyurethane foam midsoles, being manufactured by forming low-specific gravity polyurethane foam (preferably having a low specific gravity of about 0.1g/cc) on the inside, and wrapping the outside with a thin film or fabric, preferably a film formed from a resin alloyed with polyurethane or a polymer compatible with polyurethane, or a fabric formed from TPU yarn, and then foaming same.

Description

Polyurethane midsole for shoes and its manufacturing method

The present invention relates to a polyurethane midsole for shoes and a method of manufacturing the same, and more particularly, to reduce the specific gravity of the polyurethane foam to the specific gravity of the EVA foam to equal or less than to realize a lightweight, as well as the existing polyurethane foam It relates to a polyurethane midsole for shoes and a method of manufacturing the same to maintain the elastic force and cushioning as it has.

Typically, shoes are largely composed of a sole and an upper that is coupled to the top of the sole. The sole also consists of an outsole that forms the sole of the shoe and a midsole that forms the midsole of the shoe. The outsole is molded of rubber to satisfy the functions of wear resistance and slippage.The midsole is made of synthetic resin that is foamed and expanded to absorb the impact and restore the light when impact is applied, while reducing the weight of the entire shoe. Doing.

In manufacturing such shoe midsole, in the past, mainly used polyurethane foam (Polyurethane Foam) based on excellent elasticity and cushioning, but recently, EVA foam (Etylene Vinyl) in accordance with the trend (weight) is the priority Acetate Foam) has been replaced by the situation. Since the EVA foam has a low specific gravity in the final product in the manufacturing process of the midsole, by implementing a light weight that the polyurethane foam does not exhibit, most of the footwear industry is used as a raw material of the shoe midsole.

In the meantime, the method for manufacturing shoe midsole with EVA foam is a method of injecting EVA and other additives, and then directly injecting them into a conventional injection molding machine (Injection Phylon), and mixing EVA and other additives, followed by free foam. Compression Molding However, in the case of EVA foam, the weight of the product can be realized as a low specific gravity (<0.20 g / cc), but elasticity and other physical properties (specifically, cushioning, restoring force, etc.) are inferior to polyurethane foam.

In addition, a method of manufacturing a shoe midsole with a polyurethane foam is a method of forming a two-component polyurethane stock solution into a conventional foaming machine and then mixing and injecting it into a mold (foam) to foam molding. However, the polyurethane foam has an advantage of excellent elasticity and resilience, but because the specific gravity (> 0.3g / cc) is high, if a lot of foaming to lower the specific gravity, the surface of the skin is not good, the physical properties and appearance is bad.

[Preceding technical literature]

[Patent Documents]

(Patent Document 1) Published Patent Publication No. 10-2016-0114274 (name of the invention: a midsole molding apparatus and a midsole manufactured by the molding apparatus. Publication date: October 05, 2016)

(Patent Document 2) Published Patent Publication No. 10-2011-0115195 (Invention name: Midsole manufactured from synthetic resin foam beads. Publication date: October 21, 2011)

(Patent Document 3) Published Patent Publication No. 10-2013-0096660 (Invention name: shoe midsole manufacturing method and shoe midsole using the same. Publication date: August 30, 2013)

(Patent Document 4) Published Patent Publication No. 10-2016-0061463 (Invention name: Midsole having a shock-absorbing and rebound elasticity function and a manufacturing method thereof. Publication date: June 01, 2016)

The present invention is to solve the problems of the prior art as described above, to provide a polyurethane midsole for shoes and a method of manufacturing the same so that the weight of the shoe can be implemented while maintaining the elasticity and cushioning feeling when manufacturing the midsole with polyurethane foam The purpose is.

Polyurethane midsole for shoes according to the present invention is composed of a low specific gravity polyurethane foam, the bottom surface and the circumferential surface of the midsole or optionally the upper surface of the midsole frozen with a polymer compatible with polyurethane or polyurethane It is characterized in that the film made of Roy resin is wrapped.

Polyurethane midsole for shoes according to the present invention is composed of a low specific gravity polyurethane foam, the bottom and circumferential surface of the midsole or optionally the upper surface of the midsole is a film made by compounding silica or inorganic material that is wrapped It features.

Polyurethane midsole for shoes according to the present invention is composed of a low specific gravity polyurethane foam, characterized in that the bottom surface and the circumferential surface of the midsole or optionally the upper surface of the midsole is made of TPU yarn wrapped. .

Method for producing a polyurethane midsole for shoes according to the invention is a film made of a polymer compatible with polyurethane or polyurethane and alloy or silica or inorganic material in the form of a midsole through vacuum forming, and then the midsole It is put into a mold for manufacturing, put a PU preform (Free Foam) of the semi-finished form of the block mold PU foam 3D cut molded thereon, it is characterized by consisting of a process of manufacturing a midsole by compression molding it.

Method for producing a polyurethane midsole for shoes according to the present invention is made of a TPU yarn woven fabric in the form of a midsole through vacuum molding, and then put it in a mold for manufacturing the midsole, and the semi-finished product 3D cut molding a block mold PU foam thereon After placing the PU preform (Free Foam) of the form, it is characterized by consisting of a process of manufacturing a midsole by compression molding.

Method for producing a shoe polyurethane polyurethane according to the present invention comprises the steps of preparing a fabric made of a film or TPU yarn made by compounding a polymer compatible with polyurethane or polyurethane and alloy or silica or inorganic material; 3) cutting the PU foam made of low specific gravity polyurethane to produce a midsole-shaped semi-finished PU preform; wrapping the film or fabric on the outside of the PU preform by vacuum molding; Put the PU preform into a compression molding mold, it is characterized in that consisting of a step of producing a polyurethane midsole by compression molding.

The present invention is a method of manufacturing a polyurethane midsole for shoes, the inside is composed of a low specific gravity polyurethane foam and the outside is a method of wrapping with a film made of a polymer and alloy resin compatible with polyurethane or polyurethane By molding, it is possible to realize the lightweight of the shoes as well as to maintain the elasticity and cushioning of the polyurethane foam as it is.

In particular, the present invention when manufacturing a shoe polyurethane midsole, the inside is composed of a low specific weight polyurethane foam and the outside is formed by the method of wrapping by a film made by compounding silica or inorganic material to realize the above-described effect Of course, there is an advantage to prevent the phenomenon that the film collapses or melts away at high temperature and pressure during molding.

In addition, the present invention, when manufacturing the shoe polyurethane midsole, the inside is made of a low specific gravity polyurethane foam and the outside is molded by a method of wrapping with a fabric made of TPU yarn, the molding of the above-described effect, of course, molding When the air escapes during the bubble (bubble) can be prevented, and when weaving into a variety of shapes when making a fabric from TPU yarns, there is an effect that can be wrapped in a variety of patterns.

1 is a view sequentially showing a method of manufacturing a polyurethane midsole for shoes according to an embodiment of the present invention.

Figure 2 is a view showing in detail the process to manufacture a PU preform (Free Foam) shown in Figure 1 in detail.

FIG. 3 is a view illustrating a method of processing a film or fabric shown in FIG. 1 in a midsole form by a vacuum forming method and a method of manufacturing a polyurethane midsole by compression molding with a PU preform using the same;

4 is a view showing a film in the form of a midsole made by the vacuum forming method shown in FIG.

Figure 5 is a view showing a cross-section of the polyurethane midsole for shoes produced by the method shown in FIG.

Figure 6 is a view showing sequentially a manufacturing method of a shoe polyurethane midsole according to another embodiment of the present invention.

7 is a view showing the shape of the PU preform 70 made in the PU preform manufacturing step (S204) shown in FIG.

FIG. 8 schematically shows the configuration of the vacuum molding machine 50 used when the vacuum forming wrapping step S206 shown in FIG. 6 is performed.

9 to 14 sequentially show a process of wrapping a film (or fabric made of TPU yarn) along the upper surface and the rim surface of the PU prerom 70 in the vacuum forming lapping step S206 shown in FIG. 6. Each drawing being given.

15 and 16 are views illustrating a state in which the film 80 is wrapped along the upper surface and the rim surface of the PU preform 70 according to the vacuum forming wrapping step S206 shown in FIGS. 9 to 14. .

17 to 22 sequentially wrap the film (or fabric made of TPU yarn) along the bottom surface and the rim surface of the PU prerom 70 in the vacuum forming lapping step S206 shown in FIG. 6. Each drawing showing.

23 and 24 show a state in which films 80 and 90 are wrapped on the entire surface of the PU preform 70 according to the vacuum forming wrapping step S206 shown in FIGS. 17 to 22.

25 is a view showing the compression molding step (S208) and PU midsole manufacturing step (S210) shown in FIG.

26 and 27 are views showing the shape of the polyurethane midsole for shoes manufactured by the method shown in FIG.

<Explanation of symbols for main parts of drawing>

10: polyurethane foam 10a, 70: PU preform

20: film 30, 300: polyurethane midsole

50: vacuum molding machine 60: compression molding mold

80: first film 90: second film

The present invention constitutes a low specific gravity (preferably low specific gravity of about 0.1 g / cc) polyurethane foam inside, and the polymer is compatible with a thin film or fabric, preferably polyurethane or polyurethane, outside And a method of manufacturing a shoe midsole and a method of manufacturing the midsole by wrapping with a film made of an alloy (alloy) or a fabric made of TPU yarn, and then foaming it.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description will be presented a representative embodiment in the present invention to achieve the above technical problem. And other embodiments that can be presented with the present invention are replaced by the description in the configuration of the present invention.

In the present invention, when manufacturing the shoe midsole (Midsole) in the polyurethane foam, by dropping the polyurethane foam to a specific gravity equal to or less than the EVA foam to achieve the weight reduction target of the product as well as the existing polyurethane foam It is intended to implement a polyurethane midsole for shoes and a method of manufacturing the same to maintain the excellent elasticity and cushioning as it had.

Specifically, the present invention constitutes a polyurethane foam having a low specific gravity (preferably, a low specific gravity of about 0.1 g / cc) in place of the conventional integral polyurethane foam midsole, and the outside is a thin film, preferably Technical composition of a shoe midsole and a method of manufacturing the midsole by wrapping with a film made of polyurethane or a polymer compatible with polyurethane and an alloy of an alloy, and then foaming the same Suggesting.

In addition, the present invention when manufacturing a shoe polyurethane midsole, the inside is composed of a low specific weight polyurethane foam and the outside is wrapped with a film prepared by compounding (compound) silica or inorganic materials in addition to the above-mentioned resin In addition, the present invention proposes a technical configuration that can prevent the film from flowing down or melting even at a high temperature and pressure during press molding.

In addition, the present invention is to produce a polyurethane midsole for shoes, the inside is composed of a low specific weight polyurethane foam and the outside is wrapped with a fabric made of TPU yarn (preferably, the inventors patented TPU yarn) Next, by forming a midsole by foam molding it can prevent the occurrence of air bubbles in the press molding process and proposes a technical configuration capable of wrapping of various patterns (wrapping).

In each of the following examples will be described in detail a method for producing a polyurethane midsole for shoes according to the present invention.

{Example 1}

1 is a method for manufacturing a polyurethane midsole for shoes according to an embodiment of the present invention, specifically, low specific gravity polyurethane foam inside, wrapped outside the yarn made using a thin film or TPU yarn ( The drawing shows how to prepare a polyurethane midsole by wrapping and compression molding it.

Method for producing a polyurethane midsole according to the present invention comprises the steps of mixing the polyol and isocyanate (S100), mixing them and molding into a PU foam (S102), aging the PU foam (S104), aging 3D cutting of the molded PU foam (Block Molding Foam) to PU refining (hereinafter referred to as "PU Free Foam") (S106), in addition to forming a film by a vacuum molding machine Step (S108) comprises a step of making a film in the shape of a midsole, and the film and PU preforms are sequentially put into a compression molding mold and then compression molded to produce a polyurethane midsole (S110), S112.

Hereinafter, a method of manufacturing a polyurethane midsole for shoes to be implemented in the present invention will be described in detail with reference to FIGS. 2 to 5.

FIG. 2 is a view sequentially showing a process of manufacturing polyurethane foam block (Block Molding), preferably PU preform (Free Foam) in the method of manufacturing a polyurethane midsole for shoes according to the present invention, FIG. 3 is a view illustrating a process of manufacturing a film in a midsole shape by using a conventional vacuum forming method and compressing the same using a conventional compression molding mold together with a PU preform.

Referring to FIG. 2, in the present invention, a polyol and an isocyanate are mixed in a conventional method and a compounding ratio (S100), and then mixed for 10 to 15 seconds to prepare a two-component polyurethane, and then the two-component polyurethane stock solution To put in a mold, it is foam molded to prepare a PU foam (S102). At this time, the foamed PU foam has a specific gravity of 0.1 g / cc and belongs to a low specific gravity.

Thereafter, after demolding the PU foam in the mold 30 to 45 minutes, it is aged for 24 hours (S104). Subsequently, the matured PU foam (Block Molding Foam) using a conventional 3D cutting machine to make a semi-finished product in a desired form of free foam, preferably midsole shape (S106). At this time, the semi-finished product made by the 3D cutting machine is called PU preform (Free Foam, 10a) in the present invention.

Next, in the present invention, as shown in FIG. 3, the film is molded into a midsole shape using a vacuum molding machine. Specifically, the film of the polyurethane material is vacuum-molded in order to protect the outer surface of the polyurethane midsole. It is molded into the shape of midsole like 4 (hereinafter referred to as 'film 20'). At this time, the film 20 is a film made of a resin (Alloy) and a polymer compatible with polyurethane or polyurethane. In addition, the alloy alloyed with a polymer compatible with polyurethane is made of an alloy made of polyurethane resin with engineered plastics such as ABS, POM, SBS, and SEBS, and synthetic rubber such as SBS, SEBS, NBR, and BR. Say. At this time, the resin alloy serves to reduce the elasticity of the film 20 so that the angle is well formed in the midsole shape as shown in FIG.

On the other hand, in the present invention, when the film 20 is manufactured in the press molding by compounding (compound) the silica or inorganic materials in addition to the resins shown above, specifically in the production of the midsole using an extrusion molding mold for producing midsole At high temperatures and pressures, the film 20 easily flows out of the PU preform 10a to prevent it from collapsing or melting. That is, when the film 20 is manufactured, an inorganic material such as silica, calcium carbonate, and talc is used as a reinforcing agent in combination with polyurethane to achieve the above effects.

At this time, in the present invention, as shown above, when the film 20 is used, a resin alloy or a reinforcing agent is used, but a polyurethane and a resin alloy and a reinforcing agent may be compounded together.

In particular, the following shows the progress of the test when using the silica as a reinforcing agent when manufacturing the film 20, it will be described in detail. On the other hand, since the silica content and test results to be presented below can be equally applied to the first and second films 80 and 90 described in Example 2 will be omitted in Example 2 below .

1. Test progress when using silica as reinforcing agent

end. Silica Content Test

▶ Silica Masterbatch (30% Concentration Content) Content Determination Test

▶ Test the evaluation items below 0phr, 3phr, 5phr, 10phr, 20phr compound

▶ Check skin change and adhesive condition after midsole press

Base TPU film: WP-TPU (TPU / ABS Ally)

I. Test result

Testgrade MFI (200 ° C, 2.16 kg) Tfb Melt viscosity Nano Silica Masterbatch Content PU foam and compression molding after skin condition (g / 10min) (℃) (Pa.s) 180 ℃ 185 ℃ WP-TPU-1 15.82 162.3 34580 10010 0phr Skin melts and collapses, causing skin surface to boil. WP-TPU-2 13.22 164.4 36860 11440 3phr Skin melts and collapses WP-TPU-3 10.45 166.8 41950 12530 5phr Skin does not collapse and is good WP-TPU-4 7.35 168.2 43380 14230 10phr Skin does not collapse and is good WP-TPU-5 4.23 175.4 56570 17930 20phr Skin is not broken and good, adhesion is not good.

As shown in Table 1, the appropriate input content of the silica masterbatch (30% concentrated content) is preferably 5phr ~ 10phr, when 20phr is added, the product Tfb is high, the skin does not melt well during the molding press does not adhere well Did.

On the other hand, in the present invention, the polyurethane midsole of the present invention by wrapping the PU preform (10a) with a fabric made using a TPU yarn in addition to the film 20 prepared by adding the resin alloy and silica or inorganic materials ( 30) can be prepared. By using a fabric made of TPU yarns as described above, air can flow out between the spaces (holes) formed in the fabric itself during press molding, thereby preventing bubbles from being generated between the PU preform 10a and the fabric. In addition, when the fabric is made of the TPU yarn can be woven in various shapes, which has the advantage of forming a variety of patterns when wrapping the fabric on the PU preform (10a),

At this time, the TPU yarn used in the present invention is preferably to apply the technology patented by the present inventor, it is also possible to use a fabric made using a general TPU yarn. In addition, the TPU yarn patented by the inventors of the present application No. 10-1341055, No. 10-1341054, No. 10-1318135, No. 10-1530149, No. 10-1561890 It is preferable to use a TPU yarn manufactured with the technical construction disclosed in the above, and in particular, a TPU yarn prepared by compounding silica or nanosilica.

Then, the film 20 made in the shape of the midsole as shown in FIG. 4 is placed in the lower mold of the conventional compression molding mold for producing a midsole, and a low specific weight of the PU preform (10a) is put thereon to be implemented in the present invention by The polyurethane midsole 30 is prepared.

Specifically, as shown in FIG. 5, a low specific gravity (0.1 g / cc) polyurethane foam 10 is formed therein, and includes a bottom surface and an outer circumferential surface or an upper surface of the polyurethane foam 10. The entire surface is wrapped with a film (20). At this time, the film 20 can be replaced with a fabric made using a TPU yarn as seen above. In addition, the polyurethane foam 10 is made of 3D cutting (PU preform: Free Foam, 10a) made by 3D cutting (PU) foam block (foam block) processed in a block mold (block mold) in a desired form It is made by compression molding.

According to such a technical configuration, the polyurethane midsole 30 of the present invention can realize the lightweight of the shoes as a low specific gravity of the EVA level with elasticity and resilience, as well as wrap the fabric made using a film or TPU yarn on the outside In addition, film decoration is possible and various patterns can be formed in the midsole.

On the other hand, in the case of the foam to enter the inside of the polyurethane midsole according to the present invention is not necessarily PU foam, EVA foam or polyolefin foam (Polyolefin foam) is also possible. In this case, however, physical properties may be degraded.

{Example 2}

6 is a method for manufacturing a polyurethane midsole for shoes according to another preferred embodiment of the present invention, specifically, a low specific gravity polyurethane foam inside and wrapped with a fabric made using a thin film or TPU yarn on the outside (wrapping) and compression molding it is a view showing a method for producing a polyurethane midsole.

Referring to FIG. 6, the method of manufacturing a polyurethane midsole according to the present invention may include forming a PU foam in a conventional method (S200), and processing the PU foam into a PU preform by 3D cutting. Step S204, in addition to manufacturing the film shown in Example 1 described above, or manufacturing a fabric using a TPU yarn (200), the film (or fabric made of TPU yarn) and PU preform The vacuum molding step (S206), the wrapped PU preform is put into a conventional compression molding mold and compression molding to produce a polyurethane midsole to be implemented in the present invention (S208, S210).

Hereinafter, the method for preparing the polyurethane midsole shown in FIG. 6 will be presented in each step (S200 to S210), and will be described in detail with reference to FIGS. 7 to 27 in order to help understanding of the present invention.

1.PU foam molding step (S200)

Polyol and isocyanate are mixed to prepare a two-component polyurethane, which is then poured into a mold, foamed, and then matured to have a low specific gravity (preferably, a low specific gravity of about 0.1 g / cc). ).

2. PU preform manufacturing step (S204)

The PU foam is processed into a desired shape using a conventional 3D cutting machine, preferably in a midsole shape as shown in FIG. 7. In the present invention, the semi-finished product is referred to as a PU preform (Free Foam: 70).

3. Film or fabric manufacturing step (S202)

On the other hand, in the present invention when manufacturing the polyurethane midsole 300 as shown in Figure 26 and 27, for the purpose of protecting the outer surface of the midsole 300 to produce a film (80,90) or fabric and the polyurethane The entire bottom or circumferential surface or upper surface of the midsole 300 is wrapped. The film (80,90) or the fabric is to maintain the elasticity and cushioning of the polyurethane foam while maintaining the weight of the shoe as seen above when manufacturing the polyurethane midsole (300).

Such films 80 and 90 are made of polyurethane or a resin that is alloyed with a polymer compatible with the polyurethane. Preferably, the polyurethane resin is engineered to ABS, POM, SBS, SEBS, etc. It is made of plastic, synthetic rubber such as SBS, SEBS, NBR and BR and alloyed resin. Such a composition reduces the elasticity of the films 80 and 90 so that the films 80 and 90 are in close contact with the PU preform 70 as shown in FIGS. .

In addition, the films 80 and 90 may be manufactured by using a reinforcing agent in addition to the resin alloy. Specifically, silica or an inorganic material (for example, inorganic materials such as calcium carbonate and talc) may be used. This reinforcement prevents the film 80,90 from flowing down easily, even at high temperatures and pressures, and collapse or melt away (i.e., the film does not come out of contact with the PU preform).

In addition, in the present invention, the PU preform 70 may be wrapped with a fabric made using TPU yarns in addition to the films 80 and 90 manufactured using a resin alloy, silica, or an inorganic material. Wrapping using a fabric made of such TPU yarns prevents air from escaping between the spaces (or holes) formed in the fabric itself during press molding, so that bubbles do not occur between the PU preform 70 and the wrapped fabric. It is also possible to wrap various patterns. In this case, the TPU yarn may use the patented technology of the present inventors as described above, or may use a general TPU yarn.

4. Vacuum forming lapping step (S206)

The vacuum forming wrapping step S206 is a step of wrapping the film or fabric made in the film or fabric manufacturing step S22 on the PU preform 70 made in the above-described PU preform manufacturing step S204.

Lapping method proposed in the present invention is 1) a method of lapping the film only on the bottom surface and the rim surface of the PU preform, 2) a method of wrapping with a fabric made of TPU yarn only on the bottom and rim surface of the PU preform, 3) PU preform Wrapping the entire surface of the film with the film (ie, wrapping the entire surface over the top surface, including the bottom and edge), 4) wrap the entire surface of the PU preform with a fabric made of TPU yarn.

These methods differ only in the lapping workflow and the wrapping material, but the overall lapping method is the same. Therefore, in the following, a third method of the above-described lapping methods, that is, a method of wrapping the film on the entire surface of the PU preform will be described in detail. However, the present invention is not limited to the third lapping method, but the technical idea of the present invention is equally applied to the remaining lapping methods.

Meanwhile, in the present invention, when wrapping the film on the entire surface of the PU preform 70, that is, when wrapping the first film 80 and the second film 90 on the entire surface of the PU preform 70, respectively, The vacuum molding machine 50 is used, and the technical configuration of the vacuum molding machine 50 is as shown in FIG. Referring to FIG. 8, the vacuum molding machine 50 is generally provided with a wooden mold 52 and a vacuum suction duct 56 while maintaining a constant interval to simultaneously wrap a pair of PU preforms 70. In addition, a fixing frame 54 for fixing the first and second films 80 and 90 elastically and flatly above the die 52 is provided. At this time, a vacuum suction duct 56 is connected to the bottom of the die 52, and the vacuum suction duct 56 is connected to a general vacuum device (not shown).

Hereinafter, the vacuum molding wrapping step S206 to be implemented in the present invention using the vacuum molding machine 50 configured as described above will be described in detail with reference to FIGS. 9 to 24.

Referring to FIG. 9, the PU preform 70 is placed on the wooden mold 52 of the vacuum molding machine 50, and the first film 80 is fixed to the fixing frame 54. At this time, the first film 80 is preferably fixed to the fixing frame 54 while having a tension.

Next, as illustrated in FIGS. 10 and 11, the wooden mold 52 on which the PU preform 70 is placed is lifted up to be in contact with the first film 80, and the PU preform 70 pushes the first film 80 upward. As it rises, the first film 80 is convexly expanded.

12 and 13, when the air is sucked through the vacuum suction duct 56 installed below the die 52, the first film 80 is along the upper surface and the edge of the PU preform 70. Fully adhered

Next, as shown in FIG. 14, when the air intake is stopped from the vacuum suction duct 56 and the die 52 is lowered, the PU preform 70 sags downward with the first film 80 adhered thereto. It becomes. Subsequently, after separating the PU preform 70 from the fixing frame 54 and removing the remaining first film 80 that is not adhered to the PU preform 70 (finishing process), the PU as shown in FIGS. 15 and 16. The first film 80 is adhered only to the upper surface and the edge surface of the preform 70.

Subsequently, the PU preform 70 is placed on the wooden mold 52 of the vacuum molding machine 50 as shown in FIG. 17. The upper surface of the PU preform 70, that is, the portion to which the first film 80 is attached, faces downward. The PU preform 70 is placed on the die 52. In addition, the fixing frame 54 is fixed to the second film 90 flat to have a tension.

Next, as shown in FIGS. 18 and 19, the wooden mold 52 on which the PU preform 70 is placed is lifted up to be in contact with the second film 90, and the PU preform 70 pushes the second film 90 upward. Climb up to allow the second film 90 to expand.

Subsequently, when air is sucked in through the vacuum suction duct 56 installed below the die 52 as shown in FIGS. 20 and 21, the second film 90 forms a bottom surface and an edge surface of the PU preform 70. Accordingly.

Next, when the air suction is stopped from the vacuum suction duct 56 as shown in FIG. 22 and the die 52 is lowered down, the PU preform 70 sags downward with the second film 90 bonded thereto. It becomes. Subsequently, after separating the PU preform 70 from the fixing frame 54 and removing the remaining second film 90 which is not adhered to the PU preform 70 (finishing treatment), the PU preform 70 is shown in FIG. 23. The second film 90 is bonded to the bottom surface and the edge surface of the). That is, as shown in FIG. 24, the first film 80 is adhered to the upper surface and the edge of the PU preform 70, and the second film 90 is adhered to the bottom and the edge of the PU preform 70. As a result, the first and second films 80 and 90 are wrapped on the entire surface of the PU preform 70. In this case, the edge surfaces of the PU preform 70 may be overlapped and wrapped with the first and second films 80 and 90, and the first and second films 80 and 90 do not overlap with each other to form a boundary surface and the PU preform 70. It can be wrapped on the edge surface of the).

5. Compression molding step (S208) and PU midsole manufacturing (S210)

As shown in FIG. 25, the PU preform 70 having the first and second films 80 and 90 wrapped thereon is placed on the lower mold 64 of the compression molding mold 60 for manufacturing a midsole. ) And then compression molding it to produce a polyurethane midsole 300 to be implemented in the present invention.

Thus, the polyurethane midsole 300 of the present invention manufactured by the above-described method (specifically, the method of S200 to S210 shown in FIG. 6) has a low specific gravity (0.1 g / g) as shown in FIGS. 26 and 27. cc) of PU preform (70: polyurethane foam), and the entire surface including the bottom surface, the circumferential surface, and the upper surface of the PU preform 70 is wrapped with the first and second films (80, 90) have. In this case, the first and second films 80 and 90 may be wrapped only on the bottom surface and the edge surface of the PU preform 70 (polyurethane foam). The polyurethane midsole 300 illustrated in FIG. 26 has a pattern formed along a circumferential surface because a pattern is formed on the lower mold 64 of the compression molding mold 60.

On the other hand, the polyurethane midsole of the present invention prepared by the method of Examples 1 and 2 as described above can be seen that the physical properties are superior to the conventional EVA midsole and polyurethane midsole is shown in Table 2 specifically. .

TYPE Wrapper Midsole (PU base) of the present invention Conventional EVA Midsole Conventional PU Midsole Product Compression processing EVA Injection processing EVA Ether Type Hardness (Asker C) 42-47 50-55 51-55 38-42 Tensile (kgf / ㎠) Min 15 Min 20 Min 20 Min 10 Elongation (%) Min 200 Min 250 Min 250 Min 175 Split Tear (kg / cm) Min 2.0 Min 2.5 Min 2.5 Min 0.8 Tear (kg / cm) Min 10 Min 10 Min 10 Min 5 Shrinkage (%) Max 1.0 Max 2.0 Max 2.0 Max 1.0 Specific Gravity (g / cc) 0.20-0.23 0.22-0.25 0.20-0.23 0.34-0.38 Compression set (%) Max 20 Max 80 Max 60 Max 20 Ball rebound Min 55 Min 50 Min 50 Min 55

As shown in Table 2, the polyurethane midsole of the present invention has a specific gravity similar to that of the conventional EVA midsole, but shows excellent compression set results compared to the high compression set, which is a weak point of the EVA midsole. You can see that it has only advantages.

As described above, the polyurethane midsole 300 of the present invention can realize the weight of the shoe as a low specific gravity of the EVA level with elasticity and resilience, because the fabric made of a film or TPU yarn is wrapped (wrapping) on the outside Decoration is possible and various patterns can be formed on the midsole.

In addition, as seen above, in the case of a foam inserted into the polyurethane midsole according to Embodiment 2 of the present invention, an EVA foam or a polyolefin foam may be used even if the foam is not necessarily a PU foam. In this case, however, physical properties may be degraded.

Claims (8)

In the polyurethane midsole for shoes, The inside of the midsole is composed of a low specific gravity polyurethane foam, the outside of the polyurethane foam is wrapped with a film; The film is a polyurethane midsole for shoes, characterized in that produced by compounding a resin or polyurethane and reinforcing agent with a polymer compatible with polyurethane or polyurethane. The method of claim 1, The compatible polymer is a shoe polyurethane midsole, characterized in that the alloy and synthetic rubber, such as SBS, SEBS, NBR, BR and engineer plastics such as ABS, POM, SAN. The method of claim 1, The reinforcing agent is a shoe polyurethane midsole, characterized in that the silica or inorganic material. The method of claim 3, The inorganic midsole for shoes, characterized in that the calcium carbonate or talc. In the polyurethane midsole for shoes, The inside of the midsole is composed of a low specific gravity polyurethane foam, the outside of the polyurethane foam is wrapped with a fabric; Polyurethane midsole for shoes, characterized in that the fabric is made of TPU yarn. The method of claim 5, The TPU yarn is a shoe polyurethane midsole, characterized in that the yarn made by blending silica or nanosilica. In the method of manufacturing the polyurethane midsole for shoes, Making a film made of a compound made of a compound having a compatibility with polyurethane or polyurethane, an alloy of resin or silica, or an inorganic material, or a fabric made of TPU yarn in a midsole form through vacuum forming; 3D cutting molding a PU foam made of low specific gravity polyurethane to produce a midsole-shaped semi-finished PU preform; Preparation of the shoe midsole for the shoe comprising the step of placing the film or fabric of the midsole form on the compression molding mold for producing a midsole, the PU preform on it, and compression molding it to produce a polyurethane midsole Way. In the method of manufacturing the polyurethane midsole for shoes, Preparing a fabric made of a film or TPU yarn made by compounding a polyurethane or a polymer compatible with the polyurethane and an alloyed resin or silica or an inorganic material; 3D cutting molding a PU foam made of low specific gravity polyurethane to produce a midsole-shaped semi-finished PU preform; Wrapping the film or fabric on the outside of the PU preform by vacuum forming; Putting the wrapped PU preform in a compression molding mold, and compression molding it to produce a polyurethane midsole, characterized in that the manufacturing method of the shoe polyurethane midsole.

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