KR102616749B1 - Multiple injection molding method and apparatus for manufacturing multi-function sole - Google Patents

Abstract

The present invention relates to a multiple injection molding method for manufacturing a multi-function sole. Specifically, the present invention relates to an EVA resin polymerized with vinyl acetate monomer and ethylene monomer and at least one of zinc oxide, stearic acid, and calcium carbonate. A raw material mixing step of mixing the raw materials containing; Additive input step of controlling the physical properties of the multi-function sole by adding an additive containing at least one of a foaming agent and a crosslinking agent to the mixture obtained by performing the raw material mixing step; A processing step of processing the composition obtained after performing the additive input step by a processing method including at least one of pellet processing and rolling processing; And, a molding step of molding the processed composition by injecting it into a prepared mold using an injection machine. The molding step includes molding products demolded from the upper mold, middle mold, and lower mold using the composition under preset molding conditions. It is characterized by foaming to obtain an integrally bonded foam.

Description

MULTIPLE INJECTION MOLDING METHOD AND APPARATUS FOR MANUFACTURING MULTI-FUNCTION SOLE}

The present invention relates to a multiple injection molding method and device for manufacturing multi-function soles, and specifically relates to a sole manufacturing technology that seeks to simplify the process with a multiple injection process by replacing the complex remolding process used in the conventional sole manufacturing process. will be.

Shoes are manufactured to firmly support the feet on the floor, prevent loss of kinetic energy, and facilitate walking.

In general, shoes are made up of various types of parts based on an upper and a sole. The upper is manufactured through a sewing and bonding process of fabric or leather products, and the sole is based on an insole, midsole, and outsole, including an arch supporter, Various parts such as airbags, shock absorbing pads, and internal reinforcement are individually manufactured and made into a single sole through a complex adhesive process.

Meanwhile, in order to improve the prior art including such a complex adhesion process, Korean Patent Publication No. 10-2011-0047343 (Shoes with Shock Absorbing Function) combines the sole of a shoe by inserting functional parts into the basic parts. However, this manufacturing method had the limitation of not being able to simplify the number of processes because it had to go through a complex joining process instead of an adhesion process. In addition, during mass production of the product, the adhesion between each part was poor, so there was a limitation in the actual manufacturing site. There was a problem that the use of adhesive to increase the adhesion between each part was unavoidable.

Accordingly, the present invention provides a sole manufacturing technology that can simplify the process with a multi-injection process by replacing the complex remolding process used in the conventional sole manufacturing process by providing a multiple injection molding method and device for manufacturing a multi-function sole. There is a first purpose in that.

In addition, the second purpose of the present invention is to provide a sole manufacturing technology that can realize various functions and designs by solving the problem of interfacial adhesion between different materials.

In order to achieve the above-described object, the multiple injection molding method for manufacturing a multi-function sole according to an embodiment of the present invention is an EVA resin polymerized with vinyl acetate monomer (VAM) and ethylene monomer. A raw material mixing step of mixing raw materials containing at least one of zinc oxide, stearic acid, and calcium carbonate; Additive input step of controlling the physical properties of the multi-function sole by adding an additive containing at least one of a foaming agent and a crosslinking agent to the mixture obtained by performing the raw material mixing step; A processing step of processing the composition obtained after performing the additive input step by a processing method including at least one of pellet processing and rolling processing; And, a molding step of molding the processed composition by injecting it into a prepared mold using an injection machine. The molding step includes molding products demolded from the upper mold, middle mold, and lower mold using the composition under preset molding conditions. It is characterized by foaming to obtain an integrally bonded foam.

In addition, the above-described molding step uses the composition to create a high-elasticity foam in the upper mold, a shock-absorbing foam in the middle mold, and a support foam in the lower mold, and further adds silicone rubber to the composition to the high-elasticity foam and shock-absorbing foam. It is preferable to further add activated zinc oxide to the composition.

In addition, when performing the above-described molding step, different molding temperatures are set for the upper mold, middle mold, and lower mold, with the molding temperature of the high-elasticity foam being 166 to 192°C, and the molding temperature of the shock-absorbing foam being 104 to 140°C. , the molding temperature of the support foam is preferably in the temperature range of 166 to 192°C.

In addition, in the above-described molding step, the high-elasticity foam, shock-absorbing foam, and support foam produced from the upper mold, middle mold, and lower mold are placed in a preset position, and then pressed at a temperature of 165 to 180° C. for 30 minutes using a thermocompression press. It is preferable to press mold at 100 kgf/cm ² for 8 to 11 minutes.

In addition, the above-described processing step is preferably performed so that the composition is processed to include at least one of pellet processing and rolling processing with a thickness of 10 to 24 mm.

In addition, in the above-described additive addition step, it is preferable to use a JTR foaming agent containing at least azobisformamide as a foaming agent and a peroxide crosslinking agent containing at least dicumyl peroxide (DCP) as a crosslinking agent.

In addition, the above-described raw material mixing step uses an EVA resin having a vinyl acetate (VA) content of 9.3 to 28.0% by weight, and 3 to 7 parts by weight of zinc oxide and stearic acid per 100 parts by weight of the EVA resin. It is preferable to include 0.5 to 2 parts by weight of calcium carbonate and 7 to 12 parts by weight.

Meanwhile, the multi-injection molding device for producing multi-function soles is an EVA resin polymerized with vinyl acetate monomer and ethylene monomer and at least one of zinc oxide, stearic acid, and calcium carbonate. A hopper in which the raw material mixture containing the mixture is stored; A mold provided with an upper mold, a middle mold, and a lower mold; An injection machine equipped with a heating cylinder to supply the raw material mixture stored in the hopper to the mold in a plasticized state; A press machine that heat-compresses the molded products released from the mold; And, a controller that controls the operation of components including at least one of a hopper, mold, injection machine, and press machine.

In addition, the above-mentioned mold is preferably provided with a structure in which the middle plate mold is inserted and installed between the upper plate mold and the lower plate mold.

In addition, the heating temperature of the above-mentioned heating cylinder is variably controlled depending on the mold to which the raw material mixture is supplied. When supplying the raw material mixture to the upper mold, the temperature is set to 166 to 192 ℃, and when supplying the raw material mixture to the middle mold, the temperature is set to 166 to 192 ° C. A temperature of 104 to 140°C is set, and when supplying the raw material mixture to the lower mold, the temperature is preferably set to 166 to 192°C.

According to an embodiment of the present invention, it is possible to provide a sole manufacturing technology that can simplify the process with a multiple injection process by replacing the complex remolding process used in the conventional sole manufacturing process, and at the same time, By solving the problem of interfacial adhesion, it is possible to provide a sole manufacturing technology that can implement various functions and designs.

In addition, according to an embodiment of the present invention, a complex adhesive process is not required to manufacture a multi-function sole, thereby simplifying the process and reducing process costs, and in addition, environmentally harmful substances due to non-use of adhesive are reduced. This has the effect of significantly reducing emissions.

1 is a flow chart of a multiple injection molding method for manufacturing a multi-function sole according to an embodiment of the present invention.
Figure 2 is an example of an EVA formulation table that serves as a base for support foam, high-elasticity foam, and shock-absorbing foam according to an embodiment of the present invention.
Figure 3 is an example of the results of an experiment on crosslinking characteristics by temperature when mixing raw materials according to an embodiment of the present invention.
Figure 4 is an example of a table of compounding characteristics of each functional molding material constituting a multi-function sole according to an embodiment of the present invention.
Figure 5 is an example of experimental results for an adhesion test according to molding conditions according to an embodiment of the present invention.
Figure 6 is an example of a configuration diagram of a multi-injection molding device for manufacturing a multi-function sole according to an embodiment of the present invention.
Figure 7 is an example showing a mold structure of a multi-injection molding device for manufacturing a multi-function sole according to an embodiment of the present invention.
8 is a photo of the product appearance of a multi-function sole manufactured according to an embodiment of the present invention.
Figure 9 is a test report for a multi-function sole product manufactured according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Various embodiments and/or aspects are now disclosed with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth to facilitate a general understanding of one or more aspects. However, it will also be appreciated by those skilled in the art that this aspect(s) may be practiced without these specific details. The following description and accompanying drawings set forth in detail certain example aspects of one or more aspects. However, these aspects are illustrative and some of the various methods in the principles of the various aspects may be utilized, and the written description is intended to encompass all such aspects and their equivalents.

As used herein, “embodiment,” “example,” “aspect,” “example,” etc. may not be construed to mean that any aspect or design described is better or advantageous than other aspects or designs. .

Additionally, the terms "comprise" and/or "comprising" mean that the feature and/or element is present, but exclude the presence or addition of one or more other features, elements and/or groups thereof. It should be understood as not doing so.

Additionally, terms containing ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not 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 referred to as a second component, and similarly, the second component may be referred to as a first component without departing from the scope of the present invention. The term and/or includes any of a plurality of related stated items or a combination of a plurality of related stated items.

In addition, in the embodiments of the present invention, unless otherwise defined, all terms used herein, including technical or scientific terms, are as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. It has the same meaning. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the embodiments of the present invention, have an ideal or excessively formal meaning. It is not interpreted as

The present invention relates to a multiple injection molding method for manufacturing multi-function soles. By providing a multiple injection molding method and device for manufacturing multi-function soles, the complex remolding process used in the conventional sole manufacturing process is replaced by a multiple injection process. The first purpose is to provide a brush manufacturing technology that can simplify the process, and the second purpose is to provide a sole manufacturing technology that can realize various functions and designs by solving the problem of interfacial adhesion between different materials.

Hereinafter, a more detailed description of the present invention will be made with reference to the attached drawings, and multiple drawings may be simultaneously referred to in order to explain one technical feature and the components constituting the invention.

First, referring to FIG. 1, FIG. 1 shows a flowchart of a multi-injection molding method for manufacturing a multi-function sole according to an embodiment of the present invention.

As shown in Figure 1, in the present invention, zinc oxide, stearic acid, and carbonic acid are added to the EVA resin polymerized with vinyl acetate monomer (VAM) and ethylene monomer. A raw material mixing step (S10) of mixing raw materials containing at least one of calcium (calcium carbonate) may be performed.

Specifically, the above-mentioned EVA is an abbreviation for ethylene-vinyl acetate and is a copolymer of ethylene and vinyl acetate, and has the characteristic of changing physical properties depending on the content of vinyl acetate.

Briefly referring to FIG. 2, FIG. 2 shows a formulation table of EVA foam, which is the base of the EVA blend of the present invention, which will be described below. In the present invention, the composition of the polymer is changed based on the formulation table of FIG. 2 to provide various functionalities. I would like to grant.

Looking at the formulation table of the base EVA foam shown in Figure 2, it can be seen that zinc oxide, stearic acid, and titanium dioxide are used as other additives. In this case, the above-mentioned zinc oxide can be understood as being added as a foaming initiator. , it can be understood that the above-mentioned stearic acid is added as a release agent to promote crosslinking of the foam and facilitate release, and the above-mentioned titanium dioxide is added for the purpose of improving color expression by improving whiteness. It can be understood.

In addition, in Figure 2, it can be seen that dicumyl peroxide (DCP, Dicumyl peroxide), one of the peroxide crosslinking agents, is used as a crosslinking agent, and JTR foaming agent is used as a foaming agent. Looking at the properties accordingly, the EVA foam as the base is that of vinyl acetate. As the content increased, the crosslinking speed became faster, the crosslinking density increased, and the foaming ratio tended to decrease.

In addition, when EVA foam was manufactured using EVA alone, the expansion ratio was found to be 156-173%. In general, as the content of vinyl acetate decreased, the expansion ratio tended to increase, and as the expansion ratio increased, the specific gravity increased. It was found that the hardness decreased as the crosslink density decreased, and as the vinyl acetate content decreased, the tensile strength, tear strength, and elongation tended to decrease, and as the vinyl acetate content increased, the elasticity decreased. It was found that the rebound elasticity improved as the vinyl acetate content increased.

In addition, as the content of vinyl acetate decreases, the melting point increases, showing that the heat shrinkage rate of the foam improves as the content of vinyl acetate decreases. The lower the melt index (MI) of vinyl acetate, the higher the resistance to shape deformation. It was found to have excellent resilience.

In other words, when EVA foam is manufactured using EVA alone, the properties such as heat shrinkage and permanent strain are excellent, but due to its high hardness and specific gravity, other resins that can complement the shortcomings of EVA are needed to improve mechanical strength. It was predicted that a blend with was needed.

Therefore, in the present invention, calcium carbonate, which can improve mechanical strength at low cost, was added as an alternative raw material to titanium dioxide, and an EVA blend containing EVA resin, zinc oxide, stearic acid, and calcium carbonate was created, specifically the present invention. The EVA blend referred to in the invention contains 3 to 7 parts by weight of zinc oxide, 0.5 to 2 parts by weight of stearic acid, and 7 to 12 parts by weight of calcium carbonate per 100 parts by weight of EVA resin (most preferably 100 parts by weight of EVA resin). It contained 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, and 10 parts by weight of calcium carbonate.

More specifically, the EVA resin included in the above-mentioned EVA blend is preferably used with a vinyl acetate content of 9.3 to 28.0% by weight. The vinyl acetate content in the above-mentioned content range is zinc oxide, stearic acid, and carbonic acid. When mixed with calcium, the crosslinking degree can be easily controlled, so it can be understood that the mixing stability is within the content range judged to be suitable for mass production.

Meanwhile, after performing the above-described step S10, an additive injection step (S20) is performed to control the physical properties of the multi-function sole by adding an additive containing at least one of a foaming agent and a cross-linking agent to the mixture obtained by performing step S10. It can be.

As an example, in step S20 described above, a JTR-based foaming agent containing at least azobisformamide is used as a foaming agent, and a peroxide crosslinking agent containing at least dicumyl peroxide (DCP) is used as a crosslinking agent. Specifically, the above-mentioned foaming agent may be added in an amount of 1.5 to 4.8 parts by weight per 100 parts by weight of the EVA resin, and the above-mentioned crosslinking agent may be added in an amount of 0.5 to 1.9 parts by weight per 100 parts by weight of the EVA resin.

Meanwhile, after performing the above-described step S20, a processing step (S30) is performed in which the composition obtained after performing step S20 is processed by a processing method including at least one of pellet processing and rolling processing.

Preferably, in the above-described step S30, the composition is preferably subjected to processing including at least one of pellet processing and rolling processing with a thickness of 10 mm to 24 mm, and when pellet processing is performed, the composition is formed into a pellet type. , when rolling processing is performed, it may be understood that the composition is processed into a sheet type.

At this time, the above-mentioned thickness range will be understood as the value derived from multiple permanent strain experiments (50°C/6 hours) as the thickness range with the best CS characteristics.

In addition, in the above-described step S30, the description was limited to processing the composition into a type including at least one of the pellet type and the sheet type, but this processing form can be used in various processing forms such as bead type and ball type. It can be modified, modified and used.

Meanwhile, after performing the above-described step S40, a molding step (S50) is performed in which the processed composition is injected into a prepared mold using an injection machine and molded.

Specifically, the S50 step described above is performed by using the composition to foam molded products demolded (or released) from the upper mold, middle mold, and lower mold under preset molding conditions to obtain an integrally combined foam. Preferably, and more preferably, the above-mentioned composition is used to produce a highly elastic foam with a high elastic function in the upper mold, a shock-absorbing foam with a shock absorbing function in the middle mold, and a support foam in the lower mold. It is desirable to do so.

However, in order to mold a foam with the above-mentioned functions, the addition of additional raw materials to the above-mentioned composition may be required. In the present invention, silicone rubber (for example, CF201U) is added to the above-mentioned composition to produce a high elastic foam. Additional addition (preferably, 3.5 to 5 parts by weight of activated zinc oxide per 100 weight of EVA resin may be added to the above-mentioned composition to produce a shock-absorbing foam.

Meanwhile, in the injection machine, the above-described composition is melted by a heating cylinder and supplied to the mold. In the present invention, it is preferable to melt at a temperature of 171 to 179°C, most preferably 175°C. This melting temperature is This is because the crosslinking time can be shortened by about 20 to 24% compared to the temperature of 170°C, which is the temperature condition typically used for injection molding, and the uniformity of the foaming ratio can be increased by reducing the crosslinking deviation.

The experimental results for this are attached in FIG. 3, and from the experimental result data of A and B in FIG. 3, when the melt temperature is 175°C, the crosslinking density is established at a level that can provide high elasticity, and the crosslinking time is significantly shortened. You can confirm that it is.

Returning to Figure 1, in the present invention, when performing step S50, it is preferable to set the molding conditions to different conditions for each mold to solve the problem of adhesion between interfaces. This is because the EVA blend composition is injected into each mold. It can be understood that this is a solution to the problem of the cross-linking speed being different due to the time difference, preventing complete adhesion between the interfaces, and separation between the interfaces.

Specifically, the injection molding conditions established by the applicant by performing a number of experiments are that, in the case of high elastic foam, the upper mold has a temperature range of 166 to 192 ℃ (most preferably 179 ℃) to enable injection molding. Preferably, in the case of shock-absorbing foam, it is preferable that the middle mold has a temperature range of 104 to 140 ℃ (most preferably 117 ℃) to enable injection molding, and in the case of support foam, the lower mold has a temperature range of 166 to 192 ℃. It is desirable to perform injection molding within a temperature range of ℃ (most preferably 179 ℃).

In addition, in the molding step of step S50 described above, the high elastic foam, shock-absorbing foam, and support foam produced from the upper mold, middle mold, and lower mold are placed at a preset position and then pressed at 165 to 180 degrees using a heat compression press. Press molding may be performed by pressure molding at a temperature of ℃ for 8 to 11 minutes (most preferably 580 seconds).

At this time, the above-described press molding can be performed in two tracks, firstly pressing the compound at a temperature of 100 to 120 ℃ (most preferably 110 ℃) in each mold, and then secondarily pressing the compound at 150 to 190 ℃ using a press machine. The molded products demolded from the upper mold, middle mold, and lower mold were subjected to heat compression for 9 to 11 minutes (most preferably 10 minutes) using a temperature of 170°C, most preferably, under preset molding conditions. Foaming may be performed to obtain an integrally bonded foam.

For a more detailed explanation, referring to FIG. 5, as an example of an experiment for this molding method, the results of an appearance test according to molding time are attached to examine the cross-linking adhesion characteristics.

Specifically, in Figure 7, white, yellow, and red can be understood as corresponding to high elasticity foam, shock-absorbing foam, and support foam, respectively. When the molding time is 6 to 8 minutes, the shock-absorbing foam is at the interface and the interface between other foams. It was observed that the foam was not completely adhered to and separated from the foam, and only after 10 minutes was it observed that the high-elasticity foam, shock-absorbing foam, and support foam were completely cross-linked without being separated from each other.

In other words, through these experiments, it was confirmed that manufacturing a multi-function sole using EVA blend requires press molding for at least 10 minutes at a temperature of 165 to 180°C.

In addition, in Figure 4, you can see the formulation table for the support foam, high-elasticity foam, and shock-absorbing foam that was finally established based on the multiple injection molding method for manufacturing the multi-function sole described above. As a result, in the present invention, the formula used in the conventional sole manufacturing process can be seen. It has the effect of providing a sole manufacturing technology that can simplify the process with a multiple injection process by replacing the complex remolding process. At the same time, it solves the problem of interfacial adhesion between different materials and enables the implementation of various functions and designs. This has the effect of being able to provide .

In addition, the present invention does not require a complicated adhesive process to manufacture multi-function soles, thereby simplifying the process and reducing process costs. In addition, by not using adhesives, the emission of environmentally harmful substances is significantly reduced. You can even expect the effect of reducing it.

Meanwhile, in the following, we will continue the description of a multi-injection molding device for manufacturing a multi-function sole as another embodiment of the present invention.

As an explanation of this, referring to 100 in FIG. 6, 100 in FIG. 6 shows a schematic configuration diagram of a multiple injection molding device for manufacturing a multi-function sole.

As shown at 100 in FIG. 6, the present invention may largely include a hopper 10, an injection machine 20, a mold 30, a press machine 40, and a controller 50.

At this time, the above-described hopper 10 can be understood as a space in which a mixture of raw materials containing at least one of zinc oxide, stearic acid, and calcium carbonate in EVA resin polymerized with vinyl acetate monomer and ethylene monomer is stored.

At this time, it is preferable to understand that the above-mentioned mixture is the same as the mixture examined in the multiple injection molding method for manufacturing the multi-function sole mentioned above.

Meanwhile, the above-mentioned injection machine 20 is equipped with a heating cylinder 21 and performs the function of supplying the raw material mixture stored in the hopper 10 to the mold 30 in a plasticized state.

Specifically, it is preferable that the above-described heating cylinder 21 is provided with a screw to increase the convenience of transferring the mixture.

In addition, the above-described mold 30 is preferably provided to include an upper mold 31 for producing a highly elastic foam, a middle mold 32 for creating a shock-absorbing foam, and a lower mold 33 for producing a support foam. there is.

At this time, the above-mentioned upper plate mold 31 is a mold for producing a highly elastic foam as described above, the above-mentioned middle plate mold 32 is a mold for producing a shock-absorbing foam, and the above-described lower plate mold 33 is a mold for producing a support foam. However, in the present invention, the middle plate mold 32 for producing the shock-absorbing foam is provided in a structure that is inserted and installed between the upper plate mold 31 for producing the highly elastic foam and the lower plate mold 33 for producing the support foam. , while promoting multiple injections, it is possible to achieve complete interfacial adhesion of molded products molded in each mold and then demolded in a single press process.

As an example of this, referring to FIG. 7, the schematic shape of the molded products produced in the mold 30 of the present invention can be seen in FIG. 7, where P1 is a high-elasticity foam demolded from the upper mold 31. , P2 may be understood as a support foam demolded from the lower mold 33, and P3 may be understood as a shock-absorbing foam demolded from the middle mold 32.

delete

Returning to FIG. 6 and continuing the description of the multi-injection molding device for manufacturing a multi-function sole, the above-described press machine 40 functions to heat-compress the molded products removed from the mold.

At this time, the heat compression conditions of the press machine 40 described above may be understood as the same press conditions mentioned in the molding step of the multiple injection molding method for manufacturing a multi-function sole, and in the present invention, these As the press machine 40 is provided, it is possible to obtain a foam in which the high-elasticity foam, shock-absorbing foam, and support foam demolded in the injection machine 20 are integrally combined.

Meanwhile, the above-described controller 50 functions to control the operation of components including at least one of the above-described hopper 10, mold, injection machine 20, and press machine 40.

More specifically, the above-described controller 50 is an operation control command for the hopper 10, and provides control commands including power control of the hopper 10 and control of the amount of mixture supplied from the hopper 10 to the injection machine 20. It may be possible to transmit, and as a control command for the above-described mold, a control command for opening and closing the mold may be transmitted.

In addition, the above-described controller 50 will be able to control the temperature of the heating cylinder 21 provided in the injection machine 20. As an example, the controller 50 may control the temperature of the heating cylinder 21 provided in the injection molding machine 20. A temperature of 166 to 192°C is set, and when supplying the raw material mixture to the middle mold 32, a temperature of 104 to 140°C is set, and when supplying the raw material mixture to the lower mold 33, the temperature is set to 166 to 192°C. A temperature control function may be performed such that a temperature of °C is set.

At this time, it would be preferable to understand that the above-mentioned temperature control conditions are temperature control conditions for imparting high elasticity, shock absorption, and wear resistance functionality to the foam molded product produced in each mold.

Additionally, the above-described controller 50 may transmit power control commands for the press machine 40 and temperature and pressure control commands for the press machine 40 as control commands for the press machine 40 described above.

Likewise, the control conditions of the above-described press machine 40 include a pressure of 30 to 100 kgf/cm ² at a temperature of 165 to 180° C. used in the thermocompression molding step in the description of step S50 of FIG. 1. There will be, and the present invention is not limited thereto.

Meanwhile, in Figure 8, a product photo of the multi-function sole obtained from the multiple injection molding method and device for manufacturing the multi-function sole described above is attached.

When evaluating the appearance of the multi-function sole in these product photos, it was confirmed that there was no separation between the interfaces and that they were completely adhered, and that a smooth surface and sophisticated finish were achieved.

In addition, referring to FIG. 9, a test report for a multi-function sole product manufactured by the multiple injection molding method and device for manufacturing a multi-function sole described above is attached.

Specifically, the test report attached to Figure 9 is an official test report evaluated by the Korea Apparel Testing & Research Institute for the high-elasticity foam (sample A1) and the support foam (sample A2). Looking at the test report for the high-elasticity foam, specific gravity, hardness, As a result of conducting a test using compression set and heat shrinkage as test items, the test results were that specific gravity was 0.17, hardness was 32, compression set was 12%, and heat shrinkage was -0.5% in the vertical direction and 0.5% in the horizontal direction. was derived.

Looking at these test results in detail, it can be seen that while the specific gravity is low and the elongation rate is excellent, the hardness is over 30, showing sufficient mechanical strength in a highly elastic foam, and compared to the conventional compression set rate of around 80%. It was significantly reduced to 12%, and the thermal contraction rate was significantly reduced to 0.5% compared to the conventional thermal contraction rate of 2 to 5% in the horizontal and vertical directions, which showed that the shape stability was greatly improved.

Next, looking at the test report for the support foam, tests were conducted on the support foam using specific gravity, hardness, heat shrinkage, and wear resistance as test items. As a result of the test, specific gravity was 0.25, hardness was 60, and compression set was 15. %, the heat shrinkage rate was -0.5% in the horizontal direction and -0.5% in the vertical direction, and the abrasion resistance rate was 49.7%.

Judging from these test results, the support foam had a low specific gravity and had excellent elongation, but its hardness was about twice as high as that of the high-elasticity foam, showing that mechanical strength had been strengthened.

In addition, it was found that the compression permanent shrinkage rate was reduced significantly to 16% compared to the conventional level of around 80%, and the thermal shrinkage rate was also 0.5% compared to the conventional thermal contraction rate of 2 to 5% in the horizontal and vertical directions. It was found that there was a significant decrease.

In addition, the support foam had an abrasion resistance rate of close to 50% even though it was a foam, showing that the foam characteristics, which were weak in abrasion resistance, had been improved.

In other words, the present invention provides various functionality due to the multi-function sole manufacturing technology that dramatically simplifies the process steps through the multiple injection molding process without applying the complex remolding process used in the conventional sole manufacturing process. It has been confirmed that mass production of multi-function sole products is possible.

As described above, the present invention has described the multiple injection molding method and device for manufacturing a multi-function sole, but the spirit of the present invention is not limited to the embodiments presented in this specification, and those skilled in the art who understand the spirit of the present invention Within the scope of the same idea, other embodiments can be easily proposed by adding, changing, deleting, or adding components, but this will also be considered to be within the scope of the present invention.

In addition, terms such as “include,” “comprise,” or “have” as used above mean that the corresponding component may be included, unless specifically stated to the contrary, and thus do not exclude other components. Rather, it should be interpreted as being able to include other components. All terms, including technical or scientific terms, unless otherwise defined, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Commonly used terms, such as terms defined in a dictionary, should be interpreted as consistent with the meaning in the context of the related technology, and should not be interpreted in an idealized or overly formal sense unless explicitly defined in the present invention.

The above description is merely an illustrative explanation of the technical idea of the present invention, and various modifications and variations will be possible to those skilled in the art without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but rather to explain it, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

Claims (10)

In the multiple injection molding method for manufacturing multi-function soles,
EVA resin is a polymerization of vinyl acetate monomer (VAM) and ethylene monomer and contains at least one of zinc oxide, stearic acid, and calcium carbonate. A raw material mixing step of mixing the raw materials;
An additive injection step of controlling the physical properties of the multi-function sole by adding an additive containing at least one of a foaming agent and a crosslinking agent to the mixture obtained by performing the raw material mixing step;
A processing step of processing the composition obtained after performing the additive input step by a processing method including at least one of pellet processing and rolling processing; and,
A molding step of molding the processed composition by injecting it into a prepared mold using an injection machine,
The forming step is,
The composition is injected into a mold provided with an upper mold for producing high-elasticity foam, a middle mold for creating shock-absorbing foam, and a lower mold for producing support foam, thereby producing high-elasticity foam in the upper mold and shock-absorbing foam in the middle mold. , in the lower plate mold, the support foam is produced as a molded product,
To the highly elastic foam, silicone rubber is further added to the composition,
In the shock-absorbing foam, additional activated zinc oxide is added to the composition,
The forming step is,
Multiple injection molding for producing a multi-function sole, characterized in that the molded products molded in the upper mold, middle mold, and lower mold using the above composition and then demolded are foamed under preset molding conditions to obtain an integrally combined foam. method.
delete According to paragraph 1,
When performing the forming step,
The upper mold, the middle mold, and the lower mold are set at different molding temperatures,
The molding temperature of the high-elasticity foam is 166 to 192°C, the molding temperature of the shock-absorbing foam is 104 to 140°C, and the molding temperature of the support foam is in the temperature range of 166 to 192°C. Multi-function sole Multiple injection molding methods for fabrication.
According to paragraph 1,
The forming step is,
After placing the high elastic foam, shock-absorbing foam, and support foam produced from the upper mold, the middle mold, and the lower mold at a preset position, they are pressed at a temperature of 165 to 180 ° C. for 8 to 11 minutes using a heat compression press. A multiple injection molding method for manufacturing a multi-function sole, characterized by molding.
According to paragraph 1,
The processing step is,
A multiple injection molding method for manufacturing a multi-function sole, characterized in that the composition is subjected to processing including at least one of pellet processing and rolling processing with a thickness of 10 mm to 24 mm.
According to paragraph 1,
In the additive injection step,
As the foaming agent, a JTR foaming agent containing at least azobisformamide is used,
A multiple injection molding method for manufacturing a multi-function sole, characterized in that a peroxide cross-linking agent containing at least dicumyl peroxide (DCP, Dicumyl peroxide) is used as the cross-linking agent.
According to paragraph 1,
The raw material mixing step is,
Among the EVA resins, the vinyl acetate (VA) content is 9.3 to 28.0% by weight,
A multi-function sole for manufacturing a multi-function sole, characterized in that it contains 3 to 7 parts by weight of the zinc oxide, 0.5 to 2 parts by weight of the stearic acid, and 7 to 12 parts by weight of the calcium carbonate per 100 parts by weight of the EVA resin. Injection molding method.
In the multi-injection molding device for manufacturing multi-function soles,
A hopper storing a mixture of raw materials containing at least one of zinc oxide, stearic acid, and calcium carbonate in an EVA resin obtained by polymerizing vinyl acetate monomer and ethylene monomer;
A mold comprising an upper mold for producing highly elastic foam, a middle mold for creating shock-absorbing foam, and a lower mold for producing support foam;
an injection machine equipped with a heating cylinder to supply the raw material mixture stored in the hopper to the mold in a plasticized state;
A press machine that heat-compresses the molded products released from the mold; and,
A controller that controls the operation of components including at least one of the hopper, the mold, the injection machine, and the press machine,
A multiple injection molding device for producing a multi-function sole, characterized in that additional silicone rubber is added to the raw material mixture when producing the highly elastic foam, and additional activated zinc oxide is added to the raw material mixture when producing the shock-absorbing foam.
According to clause 8,
The mold is,
A multiple injection molding device for manufacturing a multi-function sole, wherein the middle plate mold is inserted and installed between the upper plate mold and the lower plate mold.
According to clause 8,
The heating temperature of the heating cylinder is variably controlled depending on the mold into which the raw material mixture is supplied,
When supplying the raw material mixture to the top mold, a temperature of 166 to 192°C is set,
When supplying the raw material mixture to the middle plate mold, a temperature of 104 to 140°C is set,
A multiple injection molding device for manufacturing a multi-function sole, wherein a temperature of 166 to 192° C. is set when supplying the raw material mixture to the lower mold.