WO2017065409A1

WO2017065409A1 - Method for producing molded article

Info

Publication number: WO2017065409A1
Application number: PCT/KR2016/009885
Authority: WO
Inventors: 이성율
Original assignee: 화인케미칼 주식회사
Priority date: 2015-10-15
Filing date: 2016-09-05
Publication date: 2017-04-20
Also published as: KR101653978B1

Abstract

A method for producing a molded article of the present invention is a method for producing a molded article having an empty space formed therein and comprises the steps of: providing a mold having a predetermined shape and having a core material fixed therein; injecting a molding material in the cavity of the mold; coagulating the molding material within the mold; separating the coagulated molded article from the mold; and removing the core material inside the separated molded article, wherein the molded article has formed thereon a core material discharge hole having the core material exposed therefrom, and the core material may be pulverized into a particle state by means of physical impact.

Description

Manufacturing method of molding

The present invention relates to a method for producing a molded article, and more particularly, to a method for manufacturing a molded article having an empty space therein.

Injection molding is a method of manufacturing a molding by melting a thermoplastic material in an extruder and injecting it into a mold. The principle of injection molding is to melt and heat a hard or soft polymer resin in a cylinder of an extruder, which has a property of flowing when heated and solidified when cooled, and injected into a cold mold through a nozzle with a plunger to produce a molded article.

A special method is required for producing moldings having an empty space therein by injection molding. This is because it is impossible to separate the injection molding from the mold if a space larger than the inlet is formed in the internal space of the injection molding. A method of forming an empty space inside the molding by injection molding is to install a core forming the empty space inside the mold and to remove the core from the molding. The core is removed by dissolving with a solvent, hydrolysis, pyrolysis, or the like.

Japanese Laid-Open Patent Publication No. 2014-034707 discloses a technique of installing a core made of a water-soluble filler in a mold, injecting a metal powder compound into the mold, forming the melt, and removing the core by dissolving it in water. Further, Japanese Laid-Open Patent Publication No. 2011-143562 discloses a technique of forming a core from a hydrolyzable polymer resin and hydrolyzing and removing the core from the molded article.

The core removal method as described above has a problem of low economical efficiency because it takes a long time to dissolve or hydrolyze the core when the empty space inside the molding is large and the inlet for removing the core is small. In addition, since the temperature of the mold is maintained at a high temperature during injection molding, there is a restriction in selecting a material of the core that does not deform at a high temperature.

Accordingly, the first problem to be solved by the present invention is to provide a method for producing a molding that can withstand the temperature of the mold or molten molding material required for injection molding or transfer molding, the removal of the core is simple, and the core can be recycled. will be.

The second problem to be solved by the present invention is to provide a tire having a feature produced by the molding production method.

In order to achieve the first object, the present invention provides a method for producing a molded article having an empty space therein, comprising: providing a mold having a predetermined shape and having a core fixed therein; and a molding material in a cavity of the mold. Injecting the mold, solidifying a molding material in the mold, separating the solidified molding from the mold, and removing a core material in the separated molding, wherein the molding includes a core material. Is provided with a core discharge hole is exposed, the core provides a method for producing a molded article, characterized in that the pulverized in the state of particles by physical impact.

According to one embodiment of the present invention, the removing of the core material in the separated molding may be performed by pulverizing the core material to remove the core material in the pulverized state through the core discharge hole.

According to another embodiment of the present invention, the core material may be manufactured by solidifying at least one selected from the group consisting of clay, loess, gypsum and cement.

According to another embodiment of the present invention, the core material may include carbonate, sulfate, hydroxide or nitrate.

According to another embodiment of the present invention, the core material may be a composite material in which filler is mixed with a polymer resin having a melting point of 180 ° C. or more.

According to another embodiment of the present invention, the core material may include an alkali metal chloride.

According to another embodiment of the present invention, the core material may include a polysaccharide.

According to another embodiment of the present invention, the molding may be a tire in which a portion except the core discharge hole is closed.

The present invention provides a tire including at least four core material discharge holes, in which an air injection space is formed and connected to the air injection space, in order to achieve the second object.

According to one embodiment of the present invention, at least one of the core discharge holes may be sealed with a polymer resin containing an adhesive component.

The manufacturing method of the molding of this invention has the following effects.

1. Since the core material having a predetermined shape is installed inside the mold, and the core material is removed after molding, a molded product having an empty space therein can be manufactured.

2. Since the core is made of a material that can be pulverized into particles by physical impact, it can be removed without consuming additional materials such as solvent or heat or energy.

3. The time taken for grinding the core material is very short compared to the time taken for dissolving or hydrolyzing the core, so that the time and cost of injection molding or transfer molding can be reduced.

4. Soil, crystalline salts, polymer-inorganic composites and polysaccharides, which are core materials, can be recycled after removal.

5. Properly mixing cores, crystalline salts, polymer-inorganic composites, polysaccharides, etc., which are core materials, can make powder grinding easier while maintaining the strength of the core.

6. When the tire is manufactured by the molding method of the present invention, it is easy to apply a physical impact for crushing the core material by the high elasticity of the tire material, the core material discharge hole used for the discharge of the crushed core material is a polymer containing an adhesive component It can be effectively sealed with a resin.

1 shows a mold used in the method for producing a molded article of the present invention.

Figure 2 shows a tire produced by the method for producing a molding of the present invention.

Figure 3 illustrates the process of manufacturing a tire by the method for producing a molding of the present invention sequentially.

4 and 5 illustrate a process of removing the core material from the inside of the tire by the manufacturing method of the molding of the present invention.

100: mold 101: first mold

102: second mold 103: heartwood

104: core material fixing portion 105: cavity

106: molding material

200: tire 201: tire body

201a: Rim fastener 202: Core discharge hole

300: washing liquid

Method for producing a molding of the present invention is a method of manufacturing a molded article having an empty space therein, providing a mold having a predetermined shape and the core material is fixed therein, and injecting a molding material into the cavity of the mold And solidifying a molding material in the mold, separating the solidified molding from the mold, and removing a core material in the separated molding, wherein the core is exposed to the molding. The discharge hole is formed, the core material is characterized in that the pulverization in the form of particles by physical impact.

The manufacturing method of the molding of this invention is for manufacturing the molding in which the empty space was formed inside. In particular, the present invention can be effectively used to manufacture tires by injection molding or transfer molding. The tire needs a space in which air is injected. In order to manufacture the tire by injection molding or transfer molding, it is necessary to effectively remove a large volume core through small holes formed in the tire body. The method for producing a molded article of the present invention is very useful for the production of tires because the time taken for removing the core can be shortened. Hereinafter, the present invention will be described taking a mold for manufacturing a tire as an example.

1 shows a mold used in the method for producing a molded article of the present invention. Referring to FIG. 1, the mold 100 includes a first mold 101 and a second mold 102 engaged with each other, a cavity 105 formed between the first mold and the second mold, and an inside of the cavity. The core member fixing part 104 and the core member 104 fixed by the core member fixing part are included. The cavity 105 formed between the first mold 101 and the second mold 102 has a donut shape, and the inside of the cavity 105 has a donut-shaped core material 103 having a smaller cross-sectional area than the cavity. It is fixed. The core fixing part 104 for fixing the core 103 is protruded from the lower cavity of the 2nd mold side. The core is formed with a hole that can be inserted into the core fixing portion 104.

Figure 2 shows a tire produced by the method for producing a molding of the present invention. Referring to FIG. 2A, the tire 200 includes a tire body 201 and a rim fastening portion 201a protruding in the inner direction of the tire body. Figure 2 (b) shows a cross section parallel to the circumference of the tire, the interior of the tire is formed with an empty space for injecting air, the tire core hole for discharging the core material in the form of crushed particles 202 is formed. The core discharge hole is preferably four or more for removal efficiency of the core. Figure 2 (c) is a cross-sectional view perpendicular to the circumferential direction of the tire, it can be seen that the core discharge hole 202 connected to the outside in the inner space of the tire. Although the thickness of the tire body around the core discharge hole 202 is formed in the drawing is the same as the thickness of the entire tire body, it is also possible to make the thickness of the tire body around the core discharge hole 202 thicker than the thickness of the entire tire body. . This is to make the sealing more solid in the structure of sealing the core discharge hole after the core is discharged, the formation of such a structure is possible by deformation of the shape of the core. That is, when the core is formed in the center of the core deeper than the hole around the hole for fixing the core fixing portion, the tire body thickness around the core discharge hole 202 to form a thicker than the overall tire body thickness Can be.

The core material used in the method for producing a molded article of the present invention must satisfy several physical properties. First, it must have heat resistance so that deformation does not occur at the temperature of the mold where injection molding or transfer molding is performed. In the case of a tire material which can be produced by injection molding or transfer molding, it is preferable that the core material has a melting point of 180 ° C or higher. Second, the core material should be easily pulverized into the particle state by physical impact. This is to easily remove the crushed core material from the core discharge hole formed in the molding. Third, the core material is preferably made of a material that can be recycled.

Various kinds of materials can be used for the manufacture of the core material as long as it satisfies the above properties. Hereinafter, the core material that can be applied to the present invention will be described with some examples. However, the kind of core material described is only a means for explaining the present invention, and the rights of the present invention are not limited by these examples.

The core material may be made of mud, salt, polysaccharide, polymer resin, or the like, and may be in the form of a single or two or more materials, and may include a large amount of filler.

The core material may be manufactured by solidifying at least one selected from the group consisting of clay, loess, gypsum and cement. The clay refers to soil which is a raw material of ceramics, tiles, and the like, and when mixed with water, kneaded and dried, a desired shape can be formed. The clay is very resistant to heat and can be pulverized by physical impact before sintering, so it can be a raw material of the core material that can be removed in a powder state. Gypsum can be a material of the core material because it can be molded when the water is mixed and can be pulverized in a granular state, and cement that is not mixed with sand or gravel can be a material of the core material because of its low strength. The core material manufactured by solidifying at least one selected from the group consisting of clay, loess, gypsum and cement may be prepared by mixing with a salt, a polysaccharide, a polymer resin, and a filler.

The core may comprise carbonate, sulfate, hydroxide or nitrate. The core may be made of the carbonate, sulfate, or hydroxide, or a mixture thereof. In addition, the core may be made of a mixture of other materials and the salts. The carbonate may be calcium carbonate, potassium carbonate, sodium carbonate, magnesium carbonate, and the like, and the sulfate may be calcium sulfate, potassium sulfate, sodium sulfate, barium sulfate, magnesium sulfate, and the like, and the hydroxide salt may be calcium hydroxide, potassium hydroxide, sodium hydroxide, magnesium hydroxide, hydroxide, or the like. Barium and the like. In addition, the salt contained in the core may be an alkali metal chloride such as calcium chloride, potassium chloride, sodium chloride, magnesium chloride. The core material may be prepared in a form in which a salt is mixed with a material made of a polysaccharide such as sugar, and may include a filler.

The core material may be manufactured in a form in which a filler is mixed with a polymer resin. The polymer resin may be a synthetic polymer such as polyvinyl alcohol, polyethylene, polypropylene, polyvinyl chloride, or the like, or a natural polymer such as starch or glue. It is preferable that a polymeric resin has melting | fusing point of 180 degreeC or more. This takes into account the melting point of the molding material used as the tire material and the temperature of the injection molding or the transfer molding die. The filler may be inorganic particles such as silica, glass powder, sand, metal powder or organic particles such as polymer resin. The mixing ratio of the polymer resin and the filler is preferably 1: 2 to 1:20 by weight. When the mixing ratio of the polymer resin and the filler is less than 1: 2, the mixing amount of the polymer resin is large, so that the core material is difficult to be crushed, and when it exceeds 1:20, it is difficult to maintain the shape of the core material. Even when the core is made of a composite material of a polymer resin and a filler, salts and polysaccharides may be mixed together in the core. When a physical impact is applied to the composite material of the polymer resin and the filler, the relatively weak strength of the polymer resin is broken and the bonding force used to bind the filler is lost. As a result, the composite material is easily crushed. At this time, the size of the filler is preferably smaller than the core discharge hole.

The heartwood may comprise polysaccharides, which may be disaccharides such as sugar. Heartwood may be made of a mixture of sugar, salt, filler, and the like.

The core material may have a form in which pores are formed therein, and a foaming agent may be mixed in the forming process of the core material for this purpose. When the pores are formed inside the core material has the advantage of reducing the material consumption of the core material, it is easy to crush the core material.

The core material may be manufactured by injection molding, transfer molding, press molding, or the like, and when the core material includes moisture, a separate drying process may be added.

When a tire is manufactured by the manufacturing method of the molded object of this invention, the core material discharge hole is formed in the molded object of a tire. The core discharge hole can be used as an air inlet for the tire, and an additional sealing process can be added if necessary. As a method of sealing the core discharge hole, a polymer resin including an adhesive component may be used. The polymer resin containing the adhesive component may be a puncture seal (a so-called "earthworm" or "sticky" product) used to repair the puncture of the tire.

Figure 3 illustrates the process of manufacturing a tire by the method for producing a molding of the present invention sequentially. First, referring to (a) of FIG. 3, a first mold 101 and a second mold 102 facing each other are prepared. A cavity forming a cross section in a direction perpendicular to the circumference of the tire is formed in the first mold and the second mold, and a core fixing part 104 is formed in the lower portion of the cavity of the second mold 102. Next, referring to FIG. 3B, the core 103 is fixed on the core fixing part 104 of the second mold. 3 (c), the mold is closed so that the first mold 101 and the second mold 102 are bitten. Subsequently, referring to FIG. 3D, the molding material 106 is injected into the cavity of the mold. The injected molding material 106 includes natural rubber, stearic acid, fillers, and the like, and the molding material is polymerized or solidified inside the cavity. Next, referring to FIG. 3E, the first mold 101 and the second mold 102 are separated. In the separated first mold 102, there is a tire body 201 that is molded and includes a core material. Subsequently, referring to FIG. 3B, the tire including the core material is separated from the second mold 102. A core discharge hole 202 is formed in the separated tire body.

Figure 4 illustrates the process of pulverizing the core material by physical impact and removing the crushed heart particles. Referring to FIG. 4A, the core material 103 is embedded in the inner space of the tire body 201. Next, referring to FIG. 4B, the core is pulverized into a particle state by applying a physical impact to the core. After this step, the pulverized core material 103a is in a state capable of exiting the core material discharge hole 202. Subsequently, referring to FIG. 4C, the pulverized core material 103a is discharged to the outside through the core material discharge hole 202 as the core material particles 103b. As such, the process of discharging the core material in the form of pulverized particles is faster than the removal method such as dissolution, melting, and hydrolysis in the related art. This is because the molded tire body has flexible physical properties that are very easily elastically deformed. That is, it is easy to crush the core material by impacting a part of the tire body, the tire body deformed during the crushing process can restore the original shape, even when the pressure is applied to the top and bottom of the tire body at the same time This is because the tire body is not damaged by the increased elasticity of the tire. Ultrasonic waves may be used for grinding the core material. Ultrasonic waves have the advantage of pulverizing the core material more uniformly and quickly.

The process of removing the core material from the inside of the tire may be performed as shown in FIG. 4, but a cleaning process may be added to additionally remove some of the material remaining in the tire.

5 illustrates a process for washing the core material remaining in the inner space of the tire from which the core material is crushed and removed. Referring to FIG. 5, some core particles 103b remain inside the tire body 201 (a). Subsequently, the washing liquid is injected into the core discharge hole (b), and the inside of the tire body is rinsed with the washing liquid to disperse the core particles in the washing liquid ((a)), and then the washing liquid is discharged through the core discharge hole ((d)). The washing liquid may be water and, if necessary, may be an organic solvent or an acidic or alkaline liquid.

Hereinafter, the present invention will be described using examples.

Example 1-1 (Manufacture of core material)

Water was poured into the clay so that the water content was 5 to 8% by weight. Subsequently, it put into the mold manufactured for tire core materials, crimped | bonded by the press, and demolded. Subsequently, the demolded core was dried in a drying chamber at 40 ° C. for 48 hours to prepare a core for producing a tire.

Example 1-2 (Manufacture of Core Material)

90 weight part of sugar, 3 weight part of silica, and 10 weight part of calcium carbonate were put into the kneader at 200 degreeC, and it mixed, and obtained the core material composition. Subsequently, the composition was pulverized to form particles having a diameter of 5 mm or less, and then charged into an injection machine hopper, adjusted to a cylinder temperature of 200 ° C., and then injected into a tire core die (mold temperature 30-40 ° C.) to prepare a tire core material. .

Example 2 (Preparation of Tire Composition)

40 parts by weight of natural rubber, 60 parts by weight of BR (butadiene rubber), 1.0 part by weight of stearic acid, 5.0 parts by weight of zinc oxide, 40 parts by weight of HAF carbon black, 2.3 parts by weight of sulfur, 1.0 parts by weight of accelerator M, 1.0 parts by weight of accelerator DM Mixing in the kneader produced a tire composition.

Example 3-1 (molding of a tire)

In the transfer molding machine, a mold having a core material pin (core material fixing part) was formed (mold temperature 150 to 180 ° C), and the core material manufactured in Example 1-1 was placed on the pin. Subsequently, after closing the mold, the tire composition prepared in Example 2 was put into a pod and pressurized to transfer the tire composition into the mold, thereby obtaining a tire with a core material.

Example 3-2 (molding of a tire)

In the transfer molding machine, a mold having a core position pin (core portion fixing portion) was mounted (mold temperature 150-180 ° C), and the core prepared in Example 1-2 was placed on the pin. Subsequently, after closing the mold, the tire composition prepared in Example 2 was put into a pod and pressurized to transfer the tire composition into the mold, thereby obtaining a tire with a core material.

Example 4-1 (removal of core material and sealing of core discharge hole)

The core was pulverized by hammering the outside of the tire molding prepared according to Example 3-1, and the core was removed through a pin hole. Subsequently, the pin hole was filled using a puncture seal, a tire repair kit.

Example 4-2 (removal of core material and sealing of core discharge hole)

The core was pulverized by hammering the outside of the tire molding prepared according to Example 3-2, and the core was removed through a pin hole. Subsequently, the pin hole was filled using a puncture seal, a tire repair kit.

Injecting air into the tire manufactured according to the above embodiments, mounted on the bicycle showed excellent running performance.

The above description has been made using the embodiments of the technical idea of the present invention, and those skilled in the art to which the present invention pertains various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments described in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims

In the manufacturing method of a molded article formed with an empty space therein,

Providing a mold having a predetermined shape and having a core fixed therein;

Injecting a molding material into the cavity of the mold;

Solidifying a molding material in the mold;

Separating the solidified molding from a mold; And

And removing the core material in the separated molding.

The molding is formed with a core discharge hole for exposing the core material, the core material is a manufacturing method of the molding, characterized in that the pulverized in the form of particles by physical impact.
The method according to claim 1,

The removing of the core material in the separated molding, pulverizing the core material to remove the core material in the pulverized particle state through the core material discharge hole, characterized in that the molding method.
The method according to claim 1,

The core material is a manufacturing method of a molded product, characterized in that manufactured by solidifying at least one selected from the group consisting of clay, loess, gypsum and cement.
The method according to claim 1,

The core material is a manufacturing method of a molding comprising a carbonate, sulfate, hydroxide or nitrate.
The method according to claim 1,

The core material is a manufacturing method of a molded product, characterized in that the filler is mixed with a polymer resin having a melting point of 180 ℃ or more.
The method according to claim 1,

The core material is a manufacturing method of a molding comprising an alkali metal chloride.
The method according to claim 1,

The core material is a manufacturing method of a molding comprising a polysaccharide.
The method according to claim 1,

The molding is a manufacturing method of the molded product, characterized in that the part of the tire except the core discharge hole is closed.
An air injection space is formed therein, and a tire including at least four core material discharge holes connected to the air injection space.
The method according to claim 9,

At least one of the core discharge hole is characterized in that the tire is sealed with a polymer resin containing an adhesive component.