JP2016000513A - Hollow elastic resin molding and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to produce a hollow elastic resin molding having a complicated inner surface shape at low cost.SOLUTION: After a core 20 is disposed inside molds 50, 51, elastic resin material is injection molded to obtain a hollow elastic resin molding 10. The core 20 is removed from the inside of the hollow elastic resin molding 10 through hydrolysis, dissolution or crushing.

Description

  The present invention relates to a production method for producing a molded body having a hollow portion using an elastic resin, and a hollow elastic resin molded body.

  Conventionally, there is a hollow elastic resin molded body formed into a hollow shape by an elastic resin. When the inner shape of the hollow elastic resin molded body is a complicated shape, for example, a plurality of metal cores are combined in a complicated manner to form a shape corresponding to the inner surface shape, and a resin is placed around the core. A method has been employed in which the material is injection molded, and then the obtained molded body is expanded with gas to remove the core from the inside, or the core is sequentially decomposed and removed from the inside.

  However, since the core must be removed, the shape of the core is subject to many restrictions. For this reason, the setting freedom degree of the inner surface shape of a hollow elastic resin molding may be low. In addition, the hollow elastic resin molded body may have a small opening and the core cannot be removed from the inside. In particular, it has been difficult to make the hollow elastic resin molded body into a bag-like shape or a complicated inner surface shape.

  For example, Patent Document 1 discloses a method for manufacturing a dust cover for a shock absorber. This dust cover has a cylindrical portion connected to the bellows cylindrical main body, and protrudes radially inward from the opening end surface of the cylindrical portion toward the main body. Protrusions are formed that are spaced apart from each other by a predetermined distance in the direction. When manufacturing the dust cover, a vulcanization molding process in which a rubber material is vulcanized on the outer periphery of the shaft-shaped molding core, and the tip of the jig between the cylindrical portion and the molding core. After inserting and scooping up the cylindrical part from the molding core, with compressed air blown from the tip of the jig, the entire dust cover is expanded radially outward, and the cylindrical part is gripped with the clamping claws. And removing the dust cover from the molding core by moving in the axial direction.

  In Patent Document 2, as a method for producing a hollow resin molded body having high hardness, a step of molding a core by injection molding a water-soluble or hydrolyzable resin A, and a core made of the resin A as a mold A step in which a molded body integrated with the core is obtained by injection molding the non-hydrolyzable and hydrophobic resin B around the core at a temperature lower than the melting point of the resin A; A step of removing only the resin B forming the core from the molded body and forming a hollow part in the molded body by autoclave curing under pressure and at a temperature lower than the melting point of the resin B; A method of performing is disclosed.

JP 2008-169891 A JP 2009-23228 A

  In Patent Document 1, compressed air is blown between the dust cover and the core to expand the dust cover, and then the core is removed. However, the inner shape of the dust cover is a more complicated shape. Then, it is difficult to expand the dust cover as a whole with compressed air, and the core cannot be removed.

  Further, in Patent Document 2, as a method for producing a resin molded product having high hardness, the core is hydrolyzed or dissolved and removed, and therefore, the core cannot be reused. As a result, the cost of the resin for forming the core and the processing cost of the core are also added, which is expensive.

  In other words, the manufacturing cost is reduced, and for example, the core is removed in a reusable form even after the core is removed from the hollow resin molded body having a small opening or a complicated inner surface shape is formed by the core. There was a request to be able to remove it, but it was not possible with the conventional one.

  The present invention has been made in view of the above points, and the object of the present invention is to form a hollow elastic resin molded body having a complicated inner surface shape and a low hardness using a core, after molding. It is intended to reduce the manufacturing cost of the hollow elastic resin molded body as a form that can be reused when the core can be removed.

  Another object of the present invention is to make it possible to manufacture a hollow elastic resin molded body having high added value, a very small opening, and low hardness.

  As a result of intensive studies to achieve the above object, the present inventors have made the following invention.

The first invention is
In the method for producing a hollow elastic resin molded body for producing a molded body having a hollow portion using an elastic resin,
A core molding step of molding a core corresponding to the shape of the hollow part;
After the core molded in the core molding step is placed in a mold, an elastic resin material is injection molded into the mold so that a part of the core can come into contact with the outside, and hollow elastic resin molding is performed. An injection molding process to obtain a body;
And a core removing step of removing the core from the inside of the hollow elastic resin molded body inside the hollow elastic resin molded body.

  According to this configuration, the core is hydrolyzed, dissolved, or crushed inside the hollow elastic resin molded body, for example, even if the hollow elastic resin molded body has only a small opening, the core is removed from the opening. It becomes possible to do. Further, even if the hollow elastic resin molded body has a complicated internal shape, it can be removed from the inside by crushing the core.

  In addition, the core is removed by physical external force without being hydrolyzed or dissolved, so that the material forming the core is not contaminated or deteriorated, and is reused as the core material. It becomes possible.

  Further, in a hollow elastic resin molded body having a high added value, the core can be removed by hydrolysis, dissolution or crushing.

According to a second invention, in the first invention,
The elastic resin material includes at least one of a thermoplastic elastomer, an ethylene / vinyl acetate copolymer, a thermoplastic urethane, and a thermosetting urethane.

  According to this configuration, the thermoplastic elastomer, ethylene / vinyl acetate copolymer, thermoplastic urethane and thermosetting urethane have physical properties similar to rubber, so even after impact or pressure is applied, It becomes possible to maintain the shape. As a result, it is possible to remove the core without pulverizing only the core by impact or pressure and damaging the hollow elastic resin molded body.

According to a third invention, in the first invention,
The core is formed of a thermoplastic resin material or a thermosetting resin material, and then removed by hydrolysis, dissolution, or crushing.

  According to this structure, since it becomes possible to shape | mold a core with the thermoplastic resin generally used at low cost, the cost of a core further reduces.

  Further, since the thermosetting resin is hard and brittle after being cured, the core is easily crushed.

  In the case of a thermoplastic resin, the hollow elastic resin molded article does not dissolve, and the core can be removed by hydrolysis or dissolution.

According to a fourth invention, in the first invention,
The core is made of an inorganic material, and the core is crushed and removed.

  According to this configuration, since the core is made of an inorganic material, the core becomes hard and brittle, and the core is easily crushed.

According to a fifth invention, in the first invention,
The core is made of an inorganic or organic powder and a thermoplastic resin or a thermosetting resin, and the core is removed by hydrolysis, dissolution or crushing.

  According to this configuration, since the amount of resin used to mold the core is reduced, the core becomes hard and brittle, and the core is easily crushed.

  The core can also be removed by hydrolysis or dissolution.

  For the dissolution, water or an organic solvent that dissolves the core without dissolving the hollow elastic resin molded body can be used.

A sixth invention is the invention according to any one of the first to fifth aspects,
The above-mentioned core is characterized in that a molding member molded in advance from a material different from the material for molding the core is inserted.

  According to this configuration, the amount of material used to mold the core is reduced. Further, when the molded member is removed from the core after molding the hollow elastic resin molded body, the trace becomes a space, so that the core can be easily crushed.

According to a seventh invention, in the fourth invention,
The inorganic substance is at least one of cement, ceramic, glass, and gypsum.

  According to this configuration, the core becomes hard and brittle, and the core is easily crushed.

  The eighth invention is a hollow elastic resin molded article produced by any one of the first to seventh methods.

  According to the first invention, since the hollow elastic resin molded body having a complicated inner surface shape can be formed using the core and the core is crushed after the molding, even if the opening of the hollow elastic resin molded body is small. The core can be removed. Furthermore, since the core is only crushed when the core is removed, the core can be formed by reuse. Therefore, the manufacturing cost of the hollow elastic resin molded product can be reduced.

  Furthermore, when manufacturing a highly elastic hollow elastic resin molded article, the core can be hydrolyzed or dissolved and removed. In this case, water or an organic solvent that hydrolyzes or dissolves the core without dissolving the hollow elastic resin molded body can be used.

  According to the second invention, since the hollow elastic resin molded body is molded with a material having physical properties close to that of rubber, only the core is crushed by impact or pressure, and the hollow elastic resin molded body is damaged. Without removing the core.

  According to the third invention, the core cost can be further reduced by molding the core with a thermoplastic resin that is generally used at low cost. Moreover, a core can be easily crushed by shape | molding a core with a thermosetting resin.

  Furthermore, in the case of a hollow elastic resin molded body having a high added value or a hollow elastic resin molded body having a small opening, water or an organic solvent that hydrolyzes or dissolves the core can be used.

  According to the fourth invention, since the core is made of an inorganic substance, the core becomes hard and brittle, and the core can be easily crushed.

  According to the fifth invention, since the amount of resin used to mold the core is reduced, the core becomes hard and brittle, and the core can be easily crushed.

  Furthermore, the powder and the core can be simultaneously removed by hydrolyzing or dissolving the core.

  According to the sixth aspect of the invention, since the molding member that has been molded in advance from a material different from the material for molding the core is inserted into the core, the use of the material required to mold the core is used. The amount can be reduced. Further, the core can be easily crushed by removing the molded member from the core after the hollow elastic resin molded body is molded.

  According to the seventh aspect, since the core is formed of at least one of cement, ceramic, glass, and gypsum, the core becomes hard and brittle, and the core can be easily crushed.

It is sectional drawing of the hollow elastic resin molding concerning embodiment. It is a side view of a core. It is a side view of an insertion member. It is a side view of the state where the insertion member was inserted in the core. (A) is sectional drawing of the shaping | molding die of a core, (b) is a (a) equivalent view of the state which shape | molded the core. (A) is sectional drawing of the shaping | molding die of a hollow elastic resin molding, (b) is a (a) equivalent view of the state which shape | molded the hollow elastic resin molding.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Hollow elastic resin molding)
FIG. 1 is a cross-sectional view of a hollow elastic resin molded body 10 according to an embodiment of the present invention. The hollow elastic resin molded body 10 is formed by injection molding a material containing at least one of a thermoplastic elastomer, an ethylene / vinyl acetate copolymer, a thermoplastic urethane and a thermosetting urethane, for example. Also, it can be injection molded using an elastic resin having rubber elasticity. When the hollow elastic resin molded body 10 is molded, the core 20 and the insertion member (molded member) 30 are used as described later.

  A hollow portion 11 is formed inside the hollow elastic resin molded body 10. Openings 12 and 12 are open on both end faces of the hollow elastic resin molded body 10. The hollow portion 11 communicates with the openings 12 and 12 and is opened to the outside by the openings 12 and 12. The inner surface shape of the hollow portion 11 is a complicated shape. That is, a plurality of concave portions 11 a having a larger diameter than the opening 12 are formed on the inner surface of the hollow portion 11.

  The thermoplastic elastomer used as the material of the hollow elastic resin molding 10 includes styrene elastomer, olefin elastomer, polyester elastomer, vinyl chloride elastomer, polyamide elastomer, polybutadiene elastomer, isoprene elastomer, ion cluster and amorphous. PE elastomer, fluorine-based elastomer, urethane-based elastomer, acrylic-based elastomer and the like can be used, and one of these or any two or more of them can be used in combination.

  Many ethylene / vinyl acetate copolymer (EVA) resins have a high ethylene content and a vinyl acetate content in the range of 3 to 40%, and these can be used. Ethylene / vinyl acetate copolymer resin is flexible up to -58 ° C, has excellent stability to water and ultraviolet rays, rubber elasticity, flexibility, toughness, low temperature characteristics, weather resistance, etc. Therefore, it is suitable as a material for the hollow elastic resin molded body 10. When the melt flow rate is constant, the rubber elasticity, flexibility, adhesiveness, transparency and the like are improved when the vinyl acetate content is increased. The ethylene / vinyl acetate copolymer resin may be used alone or in admixture of two or more.

  There are two systems of thermoplastic polyurethane (TPU). That is, depending on the type of chemical bond, there are polyester-based TPU and polyether-based TPU, which have high rubber elasticity and flexibility, and these can be used alone or in combination of two or more. .

  When there is no problem in compatibility, the thermoplastic elastomer, ethylene / vinyl acetate copolymer resin, and thermoplastic polyurethane can be mixed and used.

(Core)
FIG. 2 is a side view showing the outer shape of the core 20. The core 20 has a shape corresponding to the shape of the hollow portion 11 of the hollow elastic resin molded body 10. A taper hole 21 is formed in the core 20. The tapered hole 21 is gradually reduced in diameter toward one end in the longitudinal direction of the tapered hole 21 (the right end in FIG. 2). The tapered hole 21 is formed at the same time as the core 20 is formed by the insertion member 30 described later. Incidentally, the insertion member 30 is inserted into the taper hole 21 until the core 20 is crushed until it is crushed. The tapered hole 21 may not be formed, and in this case, the insertion member 30 is not used.

  As a material for molding the core 20, for example, a material formed by mixing one kind or two or more kinds of powders of general thermoplastic resin, thermosetting resin material, inorganic material, and organic material is used. Can be used.

  Examples of the thermoplastic resin include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS), polyvinyl acetate (PVAC), and Teflon (registered trademark) (polytetrafluoroethylene). , PTFE), ABS resin (acrylonitrile butadiene resin), AS resin (acrylonitrile styrene resin), acrylic resin (PMMA), and the like. Among these, one kind or a mixture of two or more kinds is used. be able to.

  Even if a thermoplastic resin is used as the material of the core 20, the injection molding of the hollow elastic resin molded body 10 is completed in a very short time, so that there is almost no risk that the core 20 will melt, and the desired internal shape will be obtained. Can be obtained. If the core 20 is molded from a general low-cost thermoplastic resin, a complicated inner surface shape, which has been difficult with the conventional manufacturing method, can be designed at low cost and freely.

  As a material for the core 20, engineering plastic having high heat resistance and high strength can be used. In this case, for example, polyamide (PA), polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE, modified PPE, PPO), polyester, polyethylene terephthalate (PET), glass fiber reinforced polyethylene terephthalate (GF-) PET), polybutylene terephthalate (PBT), cyclic polyolefin (COP) and the like can be mentioned, and one or any two or more of these can be used in combination. In this case, it is possible to prevent the core 20 from melting.

  Super engineering plastics having higher heat resistance and strength than the engineering plastics can also be used. In this case, for example, polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone (PSF), polyethersulfone (PES), amorphous polyarylate (PAR), liquid crystal polymer (LCP), polyetherether A ketone (PEEK), a thermoplastic polyimide (PI), a polyamideimide (PAI), etc. can be mentioned, Among these, 1 type or arbitrary 2 or more types can be mixed and used.

  Moreover, as a thermosetting resin used as the material of the core 20, for example, phenol resin (PF), epoxy resin (EP), melamine resin (MF), urea resin (urea resin, UF), unsaturated polyester resin ( UP), alkyd resin, polyurethane (PUR), thermosetting polyimide (PI), and the like. Among these, one kind or a mixture of two or more kinds can be used.

  When the core 20 is molded, a thermosetting resin can be mixed with a curing agent and cured after injection. Since the cured thermosetting resin is hard and brittle, the core 20 can be easily crushed.

  Examples of the inorganic material used as the material of the core 20 include sand, clay, ceramic (ceramics), glass, cement, plaster, and the like. To maintain the compressive strength of the core 20, ceramics, glass, and the like. Cement, gypsum and the like are preferable. In this case, cement and gypsum are effective because they can be hydrated and cured by adding water to form the core 20 having a high compressive strength, and can be easily crushed when crushed.

  As a means for further increasing the compressive strength of the core 20 and reducing the cost of the core 20, an inorganic or organic powder or filler can be added to the thermoplastic resin or thermosetting resin. Examples of the inorganic powder include calcium carbonate, barium sulfate, and aluminum hydroxide as so-called extender pigments, and further include glass fibers, glass particles, metal particles, and metal oxide particles having a larger volume. Examples of the organic powder include crosslinked resin powder and cellulose powder. The inorganic powder and organic powder described above can be used alone or in combination of two or more.

When the core 20 is crushed, PVC, PS, AS resin, and PMMA, which have low flexibility at normal temperature, are preferable.
When the core 20 is formed by mixing a resin that dissolves in an organic solvent alone or mixed, the core 20 can be dissolved and removed in an organic solvent in which the hollow elastic resin molded body 10 is not dissolved.

  Further, even when the filler is mixed with a component that is soluble or mixed with a resin that dissolves in the organic solvent, the core 20 can be dissolved and removed in an organic solvent in which the hollow elastic resin molded body 10 is not dissolved.

  The core 20 may be molded or coated with a water-soluble or hydrolyzable thermoplastic resin alone or in combination. Examples of water-soluble or hydrolyzable resins include polyvinyl alcohol (PVA), water-soluble nylon, water-soluble saturated polyester, polyvinyl butyral (PVB), isobutylene / maleic anhydride copolymer, and phenol-based water-soluble resin. Can be mentioned. These resins dissolve or hydrolyze the hollow elastic resin molded body 10 with steam or hot water of an autoclave, and are naturally discharged from the opening 12 of the hollow elastic resin molded body 10 to the outside.

  Also, inorganic or organic powders can be added to water-soluble or hydrolyzable thermoplastic resins.

  Further, in a state where the core 20 is integrated with the hollow elastic resin molded body 10, the core 20 is hydrolyzed and removed, or dissolved and removed in water or warm water, or the hollow elastic resin molded body 10 is dissolved. It is also possible to dissolve and remove the core 20 in an organic solvent that dissolves only the core 20.

(Insertion member)
FIG. 3 is a side view showing the outer shape of the insertion member 30. The insertion member 30 is inserted into the core 20.

  The insertion member 30 has a rod-shaped part 31 and a flange part 32. The rod-shaped part 31 and the collar part 32 can be comprised, for example with a metal material. Examples of the metal material include iron, aluminum, stainless steel, and titanium. The material can be selected from conditions such as compatibility with the core 20 and frequency of use. The insertion member 30 can be reused.

  The rod-shaped portion 31 is formed in a tapered shape that gradually decreases in diameter toward one end portion in the longitudinal direction (the right end portion in FIG. 3). It is preferable that the outer surface of the rod-shaped portion 31 is subjected to a mold release process using silicon, Teflon or the like in advance. The mold release treatment may be plating, plasma treatment, or the like. By performing the mold release process, the insertion member 30 can be easily removed from the core 20. By removing the insertion member 30 from the core 20, a tapered hole 21 is formed in the core 20, and the core 20 is easily crushed. When the insertion member 30 is removed from the core 20, it can be easily removed by applying an impact from the thin side of the insertion member 30 to the thick side.

(Core molding method)
Next, a method for forming the core 20 will be described. The material of the core 20 is as described above. In the case of using a thermoplastic resin or a thermosetting resin and an inorganic or organic powder (filler), a molding method by injection molding is preferable in terms of mass production.

  When the core 20 is formed of an inorganic material, sand, clay, ceramics, glass, cement, plaster, etc. can be used alone. Ceramics, glass, etc. need to be fired to increase compressive strength after molding, but cement, gypsum, etc. are mixed with water and poured into a mold to hydrate and cure, ensuring sufficient compressive strength it can.

  In the case of injection molding, for example, molding dies 40 and 41 shown in FIG. 5 can be used. The molds 40 and 41 are formed with clamping surfaces 40a and 41a for clamping the insertion member 30, respectively. The molding dies 40 and 41 are also formed with molding surfaces 40b and 41b for molding the core 20, respectively.

  Examples of the molds 40 and 41 include, but are not limited to, iron, aluminum, die steel, high speed tool steel, cemented carbide, ceramic, resin, and the like. The molding surfaces 40b and 41b of the molding dies 40 and 41 are preferably subjected to mold release treatment.

  First, the insertion member 30 is disposed inside the molds 40 and 41, and the molds 40 and 41 are closed. Then, both sides of the insertion member 30 are clamped by the clamping surfaces 40 a and 41 a of the molds 40 and 41. A cavity is formed between the insertion member 30 and the molding surfaces 40 b and 41 b of the molds 40 and 41. Thereafter, the material of the core 20 is injected into the cavity from a gate (not shown).

  The temperature of the resin material at this time is not a problem as long as the resin flows in the cavity and does not decompose, but is preferably 100 ° C. or higher and 400 ° C. or lower, more preferably 150 ° C. or higher and 300 ° C. or lower. is there. In particular, when the temperature is 80 ° C. or lower, the fluidity of the resin is deteriorated, and there is a possibility that the resin cannot be sufficiently filled in the cavity. If the temperature of the resin material exceeds 400 ° C., the resin material is decomposed, which is not preferable.

  The cylinder temperature of the injection molding machine at the time of injection is preferably 120 ° C. or higher and 350 ° C. or lower, more preferably 150 ° C. or higher and 300 ° C. or lower. When the cylinder temperature is lower than 120 ° C, the temperature of the resin material does not exceed 100 ° C, and when the cylinder temperature is higher than 400 ° C, the temperature of the resin material exceeds 400 ° C, which is not preferable.

  Further, the temperature of the molding surfaces 40b and 41b of the molds 40 and 41 is preferably 10 ° C. or higher and 200 ° C. or lower, and more preferably 20 ° C. or higher and 150 ° C. or lower. When the temperature of the molding surfaces 40b and 41b is lower than 10 ° C., the resin material is instantaneously cooled and solidified in the cavity, so that the filling is insufficient. If the temperature of the molding surfaces 40b and 41b is higher than 200 ° C., the resin material is softened until the mold release and the core 20 having a desired shape cannot be obtained.

Moreover, the injection molding pressure is preferably 300 kgf / cm ² or more and 2500 Kgf / cm ² or less, more preferably 500 Kgf / cm ² or more and 2000 Kgf / cm ² or less. When the injection molding pressure is lower than 300 kgf / cm ² , the resin material cannot be sufficiently filled into the cavity. When the injection molding pressure is higher than 2500 kgf / cm ² , an excessive load is applied to the injection molding apparatus, which is not preferable.

  In order to prevent the resin material from foaming or swelling due to the influence of moisture during injection molding, it is preferable to dry the resin material in advance. The temperature at which the resin material is dried is preferably 40 ° C. or higher and 150 ° C. or lower, more preferably 50 ° C. or higher and 100 ° C. or lower. The drying time is preferably 30 minutes or longer and 5 hours or shorter, more preferably 1 hour or longer and 3 hours or shorter.

  When the resin material is cooled and solidified in the molds 40 and 41, the core 20 is obtained with the insertion member 30 inserted. The above is the core molding process.

  In the core molding step, the core 20 is molded with the insertion member 30 inserted, so that the volume of the insertion member 30 and the amount of resin used in the core 20 are reduced.

(Method for forming hollow elastic resin molding)
Next, a method for forming the hollow elastic resin molded body 10 will be described. The hollow elastic resin molded body 10 is molded after the core molding step.

  The material of the hollow elastic resin molded body 10 is as described above. When using a material that can be injection-molded, for example, molding dies 50 and 51 shown in FIG. 6 can be used.

  The molding dies 50 and 51 are formed with clamping surfaces 50a and 51a for clamping a part of the insertion member 30 and the core 20, respectively. Molding surfaces 50b and 51b for molding the hollow elastic resin molded body 10 are also formed on the molds 50 and 51, respectively.

  Examples of the molds 50 and 51 include, but are not limited to, iron, aluminum, die steel, high-speed tool steel, cemented carbide, ceramic, resin, and the like. The molding surfaces 50b and 51b of the molding dies 50 and 51 are preferably subjected to mold release treatment.

  First, the insertion member 30 is disposed together with the core 20 inside the molds 50 and 51, and the molds 50 and 51 are closed. Then, both sides of the insertion member 30 and a part of the core 20 are clamped by the clamping surfaces 50 a and 51 a of the molds 50 and 51. In this state, a cavity is formed between the core 20 and the molding surfaces 50b and 51b of the molds 50 and 51. Thereafter, the material of the hollow elastic resin molded body 10 is injected into the cavity from the gate 51 c provided in the mold 51.

  The temperature of the resin material at this time is not a problem as long as the resin flows in the cavity and does not decompose, but is preferably 100 ° C. or higher and 400 ° C. or lower, more preferably 150 ° C. or higher and 300 ° C. or lower. is there. In particular, when the temperature is 80 ° C. or lower, the fluidity of the resin is deteriorated, and there is a possibility that the resin cannot be sufficiently filled in the cavity. If the temperature of the resin material exceeds 400 ° C., the resin material is decomposed, which is not preferable.

  The cylinder temperature of the injection molding machine at the time of injection is preferably 120 ° C. or higher and 350 ° C. or lower, more preferably 150 ° C. or higher and 300 ° C. or lower. When the cylinder temperature is lower than 120 ° C, the temperature of the resin material does not exceed 100 ° C, and when the cylinder temperature is higher than 400 ° C, the temperature of the resin material exceeds 400 ° C, which is not preferable.

  The temperature of the molding surfaces 50b and 51b of the molds 50 and 51 is preferably 10 ° C. or higher and 200 ° C. or lower, and more preferably 20 ° C. or higher and 150 ° C. or lower. If the temperature of the molding surfaces 50b and 51b is lower than 10 ° C., the resin material is instantaneously cooled and solidified in the cavities, so that the filling is insufficient. If the temperature of the molding surfaces 50b and 51b is higher than 200 ° C., the resin material is softened until demolding, and the hollow elastic resin molded body 10 having a desired shape cannot be obtained.

Moreover, the injection molding pressure is preferably 300 kgf / cm ² or more and 2500 Kgf / cm ² or less, more preferably 500 Kgf / cm ² or more and 2000 Kgf / cm ² or less. When the injection molding pressure is lower than 300 kgf / cm ² , the resin material cannot be sufficiently filled into the cavity. When the injection molding pressure is higher than 2500 kgf / cm ² , an excessive load is applied to the injection molding apparatus, which is not preferable.

  In order to prevent the resin material from foaming or swelling due to the influence of moisture during injection molding, it is preferable to dry the resin material in advance. The temperature at which the resin material is dried is preferably 40 ° C. or higher and 150 ° C. or lower, more preferably 50 ° C. or higher and 100 ° C. or lower. The drying time is preferably 30 minutes or longer and 5 hours or shorter, more preferably 1 hour or longer and 3 hours or shorter.

  For example, fibers such as cotton, nylon, and aramid and a base fabric may be placed in the cavity and molded together with the resin. Thereby, the hollow elastic resin molding 10 is reinforced by the fiber or the base cloth, and the physical strength of the hollow elastic resin molding 10 can be increased.

  In addition, it is also possible to manufacture the molded object of the integral thing from which hardness differs with the site | part of the hollow elastic resin molding 10 by carrying out what is called two-color molding of the hollow elastic resin molding 10. FIG. Since a two-color molding machine having a conventionally known configuration can be used, detailed description is omitted, but the injection molding machine is provided with two injection cylinders, and resin materials having different hardness from these injection cylinders. Each can be injected. Resin is injected from one injection cylinder into the mold and part of the hollow elastic resin molded body 10 is molded, and then the mold is exchanged, or another part of the cavity is separated from the other injection cylinder. The remaining portion of the hollow elastic resin molded body 10 is molded by injecting the resin. Not only the hardness of the resin but also the color and material can be changed depending on the portion of the hollow elastic resin molded body 10.

  While the resin material is cooled and solidified in the molds 50 and 51, it is molded by the molding surfaces 50 b and 51 b and also by the core 20. The above is the injection molding process.

  In the injection molding step, the temperature of the molten resin that becomes the hollow elastic resin molded body 10 is preferably lower than the melting temperature of the resin of the core 20, but may be equal to or higher than the melting temperature of the resin of the core 20. Even when the temperature of the molten resin that becomes the hollow elastic resin molded body 10 is equal to or higher than the melting temperature of the resin of the core 20, the time for molding the molten resin that becomes the hollow elastic resin molded body 10 is, for example, 0.5 to 1. Since the heat capacity of the core 20 and the heat capacity of the insertion member 30 are short as about 5 seconds, the molten resin is solidified before the core 20 is melted.

  In the injection molding process, the hollow elastic resin molded body 10 in which the core 20 is contained is obtained. Further, the insertion member 30 is inserted into the core 20. In order to obtain the hollow elastic resin molded body 10 as the final product from this state, the insertion member 30 is first removed from the core 20. At this time, since the insertion member 30 has a tapered shape, the insertion member 30 can be easily pulled out by applying an impact from the thin side of the insertion member 30 to the thick side. Since the tapered hole 21 shown in FIG. 2 is formed inside the core 20 from which the insertion member 30 has been removed, the core 20 becomes hollow.

  Thereafter, the core 20 is crushed inside the hollow elastic resin molded body 10. At this time, for example, a crushing force (for example, impact or pressure) is applied from the outside of the hollow elastic resin molded body 10. Since the crushing force is transmitted to the core 20 through the hollow elastic resin molded body 10, the core 20 is crushed. Since the core 20 to which the crushing force is applied is hollow, it can be easily crushed as compared with a solid case. Even if the inner shape of the hollow elastic resin molded body 10 is complicated and the core 20 is intricate, the hollow elastic resin molded body 10 itself is elastically deformed by the crushing force. A crushing force can be applied, and the core 20 can be crushed to every corner.

  Next, the crushed core 20 is taken out from the opening 12 of the hollow elastic resin molded body 10. At this time, since the core 20 is crushed and reduced in size, it can be easily taken out even if the opening 12 is small. The above is the core removal step.

  Since the core 20 is removed from the inside of the hollow elastic resin molded body 10 by physical external force without being hydrolyzed or dissolved, the material forming the core 20 is not contaminated or deteriorated. It becomes possible to use it as the material of the core 20 by utilizing.

  Further, when the core 20 is hydrolyzed or dissolved in water or an organic solvent, and when powder is mixed with this, the core 20 should be removed from the very small opening 12 with steam, hot water, or an organic solvent. Is possible.

  As described above, according to the hollow elastic resin molded body 10 and the method for manufacturing the hollow elastic resin molded body 10 according to this embodiment, the hollow elastic resin molded body 10 having a complicated inner surface shape using the core 20 is obtained. Since the core 20 is crushed after molding, the core 20 can be removed even if the opening 12 of the hollow elastic resin molded body 10 is small. Further, since the core 20 is only crushed when the core 20 is removed, the core 20 can be formed by reuse. Therefore, the manufacturing cost of the hollow elastic resin molded body 10 can be reduced.

  In addition, since the hollow elastic resin molded body 10 is molded from a material having physical properties close to rubber, only the core 20 is pulverized by impact or pressure, and the hollow elastic resin molded body 10 is not damaged. The core can be removed.

  Moreover, the cost of the core 20 can be further reduced by molding the core 20 using a thermoplastic resin that is generally used at a low cost. Moreover, the core 20 can be easily crushed by molding the core 20 with a thermosetting resin.

  Moreover, by making the core 20 into an inorganic substance, the core 20 becomes hard and brittle, and the core 20 can be easily crushed.

  Moreover, since the insertion member 30 previously molded with a material different from the material for molding the core 20 is inserted into the core 20, the amount of material used to mold the core 20 is reduced. it can. Further, by removing the insertion member 30 from the core 20 after the hollow elastic resin molded body 10 is molded, the core 20 can be made hollow and easily crushed.

  Furthermore, when the hollow elastic resin molded body 10 with high added value is molded or when the opening 12 is very small, the core 20 can be removed by hydrolysis or dissolution in water or an organic solvent, or powder can be removed. The core 20 can be removed by mixing the body with steam, hot water, or an organic solvent.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

  The insertion member 30 was made of iron, and the shape of the insertion member 30 was the shape shown in FIG.

The material of the core 20 was thermoplastic polyvinyl alcohol (Kuraray Co., Ltd. Kuraray Popal CP-1210). This polyvinyl alcohol was dried at 80 ° C. for 1 hour. The conditions for injection molding the core 20 were a cylinder temperature of 180 ° C., molding surfaces 40a and 41a of the molds 40 and 41 at a temperature of 60 ° C., and an injection molding pressure of 1000 kgf / cm ² . Resin was molded under these conditions to obtain a core 20 in which the insertion member 30 was integrated as shown in FIG.

The material of the hollow elastic resin molding 10 was a hydrogenated styrene thermoplastic elastomer (Tuftec P-500 manufactured by Asahi Chemicals Corporation). This hydrogenated styrene thermoplastic elastomer was dried at 80 ° C. for 1 hour. The conditions for injection molding the hollow elastic resin molded body 10 were a cylinder temperature of 160 ° C., molding surfaces 50 a and 51 a of the molds 50 and 51, a temperature of 30 ° C., and an injection molding pressure of 1500 kgf / cm ² . Resin was molded under these conditions to obtain a hollow elastic resin molded body 10 as shown in FIG.

  After the resin was solidified, when an impact was applied from a thin side to a thick side of the insertion member 30 with a hammer, the insertion member 30 was easily removed from the core 20. As a result, the core 20 becomes hollow.

  Thereafter, when the hollow elastic resin molded body 10 was struck from the outside with a hammer and the crushing force was applied to the core 20, the core 20 was easily crushed. The crushed core 20 could be removed from the opening 12 of the hollow elastic resin molded body 10. As a result, a hollow elastic resin molded body 10 having a complicated inner surface shape and a small opening 12 was obtained.

  The core 20 in a crushed state removed from the hollow elastic resin molded body 10 can be used again as a material for molding the core 20.

  The insertion member 30 and the core 20 are the same as those in the first embodiment.

The material of the hollow elastic resin molding 10 was an ethylene / vinyl acetate copolymer resin (Novatec EVALV440 manufactured by Nippon Polyethylene Co., Ltd.). The ethylene / vinyl acetate copolymer resin was dried at 60 ° C. for 1 hour. The conditions for injection molding the hollow elastic resin molded body 10 were a cylinder temperature of 120 ° C., molding surfaces 50 a and 51 a of the molds 50 and 51, a temperature of 30 ° C., and an injection molding pressure of 1300 Kgf / cm ² . Resin was molded under these conditions to obtain a hollow elastic resin molded body 10 as shown in FIG.

  After the resin was solidified, when an impact was applied from a thin side to a thick side of the insertion member 30 with a hammer, the insertion member 30 was easily removed from the core 20. As a result, the core 20 becomes hollow.

  Thereafter, when the hollow elastic resin molded body 10 was struck from the outside with a hammer and the crushing force was applied to the core 20, the core 20 was easily crushed. The crushed core 20 could be removed from the opening 12 of the hollow elastic resin molded body 10. As a result, a hollow elastic resin molded body 10 having a complicated inner surface shape and a small opening 12 was obtained.

  The insertion member 30 and the core 20 are the same as those in the first embodiment.

The material of the hollow elastic resin molding 10 was thermoplastic polyurethane (Elastolan C-85A manufactured by BSF). This thermoplastic polyurethane was dried at 80 ° C. for 1 hour. The conditions for injection molding the hollow elastic resin molded body 10 were a cylinder temperature of 200 ° C., molding surfaces 50 a and 51 a of the molds 50 and 51, a temperature of 50 ° C., and an injection molding pressure of 150 kgf / cm ² . Resin was molded under these conditions to obtain a hollow elastic resin molded body 10 as shown in FIG.

  After the resin was solidified, when an impact was applied from a thin side to a thick side of the insertion member 30 with a hammer, the insertion member 30 was easily removed from the core 20. As a result, the core 20 becomes hollow.

  Thereafter, when the hollow elastic resin molded body 10 was struck from the outside with a hammer and the crushing force was applied to the core 20, the core 20 was easily crushed. The crushed core 20 could be removed from the opening 12 of the hollow elastic resin molded body 10. As a result, a hollow elastic resin molded body 10 having a complicated inner surface shape and a small opening 12 was obtained.

  In the same manner as in Example 1, the hollow elastic resin molded body 10 in which the core 20 and the insertion member 30 were integrated was obtained. This was subjected to dissolution treatment with hot water stirred at 95 ° C. for 48 hours. When the hollow elastic resin molded body 10 was recovered, the PVA that was the material of the core 20 was not dissolved in the hot water, and the hollow elastic resin molded body 10 from which the insertion member 30 was separated was obtained.

  The core 20 and the insertion member 30 are the same as those in the first embodiment. The hollow elastic resin molding 10 integrated with the core 20 and the insertion member 30 was obtained. However, in Example 5, elastomers having different hardnesses were injection-molded on the upper and lower parts of the mold using a two-color molding machine.

  That is, first, Tuftec H1221 (manufactured by Asahi Kasei Chemicals Corporation) was injection-molded as a hydrogenated styrene-based elastomer, and then Tuftec H1041 (manufactured by Asahi Kasei Chemicals Corporation) was injection-molded as a hydrogenated styrene-based elastomer. The hardness of Tuftec H1221 is 42 by ISO7619 durometer (type A), and the hardness of Tuftec H1041 is 84.

  The obtained product was dissolved in hot water stirred at 95 ° C. for 48 hours. When the hollow elastic resin molded body 10 was recovered, the PVA that was the material of the core 20 was not dissolved in the hot water, and the hollow elastic resin molded body 10 from which the insertion member 30 was separated was obtained. The hollow elastic resin molded body 10 had different hardness in the upper and lower sides, a complicated inner surface shape, and a small opening 12.

  In addition, the above-mentioned embodiment is only a mere illustration in all points, and should not be interpreted limitedly. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  As described above, the present invention can be used, for example, when obtaining a hollow elastic resin molded body having a complicated inner surface shape.

10 Hollow elastic resin molding 20 Core 30 Insertion member (molding member)
40, 41 Core mold 50, 51 Hollow elastic resin mold

Claims (8)

In the method for producing a hollow elastic resin molded body for producing a molded body having a hollow portion using an elastic resin,
A core molding step of molding a core corresponding to the shape of the hollow part;
After the core molded in the core molding step is placed in a mold, an elastic resin material is injection molded into the mold so that a part of the core can come into contact with the outside, and hollow elastic resin molding is performed. An injection molding process to obtain a body;
A method for producing a hollow elastic resin molded body, comprising: a core removing step of removing the core from the inside of the hollow elastic resin molded body inside the hollow elastic resin molded body. In the manufacturing method of the hollow elastic resin molding of Claim 1,
The method for producing a hollow elastic resin molded article, wherein the elastic resin material contains at least one of a thermoplastic elastomer, an ethylene / vinyl acetate copolymer, a thermoplastic urethane, and a thermosetting urethane. In the manufacturing method of the hollow elastic resin molding of Claim 1,
A method for producing a hollow elastic resin molded article, wherein the core is molded with a thermoplastic resin material or a thermosetting resin material and then removed by hydrolysis, dissolution or crushing. In the manufacturing method of the hollow elastic resin molding of Claim 1,
A method for producing a hollow elastic resin molded article, wherein the core is made of an inorganic material, and the core is crushed and removed. In the manufacturing method of the hollow elastic resin molding of Claim 1,
The core comprises an inorganic or organic powder and a thermoplastic resin or a thermosetting resin, and the core is hydrolyzed, dissolved or crushed and removed to produce a hollow elastic resin molded product Method. In the manufacturing method of the hollow elastic resin molding as described in any one of Claim 1 to 5,
A method for producing a hollow elastic resin molded body, wherein a molded member molded in advance from a material different from a material for molding the core is inserted into the core. In the manufacturing method of the hollow elastic resin molding of Claim 4,
The method for producing a hollow elastic resin molded article, wherein the inorganic substance is at least one of cement, ceramic, glass, and gypsum.   A hollow elastic resin molded article produced by the method according to any one of claims 1 to 7.

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