JP2008248059A - Method for producing porous form - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a porous form, enabling a pore-forming agent to be completely removed in a short time from a solid form. <P>SOLUTION: The method for producing the porous form with open cells comprises the kneading step of dispersing the pore-forming agent in a polymeric material into a molding compound, the step of molding a solid form from the molding compound, and the step of removing the pore-forming agent from the solid form. In this method, the removing step comprises either one of the means described below: (1) applying high-pressure steam on the solid form. (2) Irradiating the solid form with ultrasonic waves in a solvent in which the pore-forming agent is dissolved. (3) Repeatedly pressurizing the solid form using a pressurizing member in the solvent in which the pore-forming agent is dissolved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a porous body.

  As a method for producing a porous body, a method using a granular pore forming agent that partially melts at the molding temperature of a solid molded body has been proposed (for example, see Patent Document 1). This method is a step of homogeneously kneading a polymer substance, a particulate pore forming agent, and other additives added as necessary, and molding a solid molded body at a temperature at which a part of the particulate pore forming agent melts ( Hereinafter, it is also referred to as “molding step”) and a step of extracting the pore-forming agent using a solvent that does not dissolve the polymer substance but dissolves the particulate pore-forming agent in the obtained solid molded body (hereinafter referred to as “extraction step”). ")"). Since this method forms a solid molded body at a temperature at which a part of the pore forming agent melts in the molding step, a homogeneous porous body having communication holes is obtained by connecting the melted pore forming agent to each other. Can do.

On the other hand, an extraction process is performed by immersing a sheet-like solid molded object in a bathtub, and always circulating the extraction solvent set to predetermined temperature. However, this method has a problem that the concentration gradient is generated and the diffusion takes time to completely remove the pore forming agent from the solid molded body, and the extraction process takes a lot of time, so that the productivity is not excellent. .
JP 2002-194131 A

  An object of the present invention is to provide a method for producing a porous body capable of completely removing a pore-forming agent from a solid molded body in a short time.

The method for producing a porous body according to the present invention includes a kneading step in which a pore-forming agent is dispersed in a polymer substance to form a molding material, a molding step for molding a solid molded body from the molding material, and the pore formation from the solid molded body. In the manufacturing method of the porous body which has a communicating hole including the removal process which removes an agent,
The removal step includes at least one of the following means (1) to (3).

  (1) Means for applying high-pressure steam to the solid molded body.

  (2) Means for irradiating the solid molded body with ultrasonic waves in a solvent in which the pore-forming agent is dissolved.

  (3) Means for repeatedly applying pressure to the solid molded body using a pressure member in a solvent in which the pore-forming agent is dissolved.

  In the method for producing a porous body according to the present invention, the pore forming agent may be pentaerythritol containing impurities.

  In the method for producing a porous body according to the present invention, the solvent may be water or warm water.

  In the method for producing a porous body according to the present invention, a surfactant can be further added to the solvent.

  In the method for producing a porous body according to the present invention, the polymer substance is a silicone resin, a polypropylene resin, a fluororesin, an epoxy resin, a silicone rubber, or a fluororubber, and means for applying high-pressure steam to the solid molded body After use, means for repeatedly applying pressure to the solid molded body using ultrasonic means or a pressure member in a solvent in which the pore-forming agent is dissolved can be used.

  In the method for producing a porous body according to the present invention, the polymeric substance is rubber, and ultrasonic waves are applied to the solid molded body in a means for applying high-pressure steam to the solid molded body or a solvent in which a pore-forming agent is dissolved. After using the means for irradiating, a means for repeatedly applying pressure to the solid molded body using a pressure member in a solvent in which the pore-forming agent is dissolved can be used.

  Hereinafter, embodiments of the present invention will be described in detail.

  First, the molding material used with the manufacturing method of the porous body which concerns on embodiment of this invention is demonstrated.

1. Molding material The molding material used in the method of the present invention is obtained by dispersing a pore-forming agent in a polymer substance forming a skeleton of a porous body.

1.1 Polymer Material The polymer material that can be used in the present invention may be any material that can adjust the fluid state before molding. If the polymer substance is in a fluid state, the pore forming agent can be uniformly dispersed by kneading. Polymeric substances that can adjust the fluid state before molding include thermoplastic resins and thermoplastic elastomers that can be melted by raising the temperature, thermosetting resins or rubbers that exist in the fluid state and are cured by crosslinking before molding. Can be mentioned.

  Examples of the thermoplastic resin include polyethylene, polystyrene, AS resin (acrylonitrile-styrene copolymer resin), ABS resin (acrylonitrile-butadiene-styrene copolymer resin), ethylene-α-olefin copolymer, polypropylene, polyamide 6, 6, polycarbonate, polyacetal and the like. These thermoplastic resins are preferably used because they can be easily injection molded or extruded. These thermoplastic resins can use 1 type, or 2 or more types of mixtures as a polymeric material.

A thermoplastic elastomer is comprised from the soft segment which shows rubber-like elasticity, and the hard segment used as the knot of a three-dimensional network. Thermoplastic elastomers exhibit rubber elasticity at room temperature and are plasticized at high temperatures, so that they can be injection molded or extruded. As the thermoplastic elastomer, for example,
(1) polystyrene elastomer with hard segment made of polystyrene and soft segment made of polybutadiene, polyisoprene, or hydrogenated products thereof (2) hard segment made of polyethylene or polypropylene, soft segment made of butyl rubber or EPDM (ethylene-propylene-diene (3) Polyolefin elastomer (3) Polyamide elastomer (3) Hard segment is polyamide and Soft segment is polyester or polyether (eg nylon 12)
(4) Polyester elastomer whose hard segment is polyester and soft segment is polyether (5) Polyurethane elastomer whose hard segment is polyurethane block having urethane bond and soft segment is polyester or polyether, etc. . These thermoplastic elastomers can use 1 type, or 2 or more types of mixtures as a polymeric material. Moreover, these thermoplastic elastomers can also be used by mixing with the above thermoplastic resins.

  The thermosetting resin can be used by crosslinking and curing a liquid prepolymer that is an initial condensate during molding. As the thermosetting resin, for example, a urethane prepolymer, an unsaturated polyester resin, an epoxy resin, a novolac resin, a resole resin, or the like can be used. These thermosetting resins may be used together with a curing agent, or may be cured by dynamic crosslinking during injection molding or extrusion molding.

  Examples of the rubber include natural rubber, silicone rubber, fluoro rubber, EPDM (ethylene propylene diene terpolymer), BR (butadiene rubber), IR (isoprene rubber), SBR (styrene butadiene rubber), NBR (acrylonitrile butadiene). Synthetic rubber such as rubber), liquid rubber whose molecular weight is reduced by depolymerization, and the like can be used.

  The blending amount of the polymer substance in the molding material can be appropriately selected according to the porosity of the porous body to be produced. In order to produce a porous body having a porosity of 50% or more, in which the production method of the present invention is particularly useful, 1 to 60% by volume, particularly 1 to 50% by volume, and further 5 to 40% by volume of the molding material. Is preferred. When the blending amount of the polymer substance exceeds 60% by volume of the molding material, a portion that does not form communication holes exists in the porous body, and the pore forming agent remains in the porous body.

1.2 Pore-Forming Agent As the pore-forming agent that can be used in the present invention, for example, one that does not melt at the kneading temperature but melts at the molding temperature can be used. Examples of the pore forming agent include polyhydric alcohols having about 2 to 5 carbon atoms such as pentaerythritol, L-erythritol, D-erythritol, meso-erythritol, and piconal; monosaccharides such as glucose, fructose, sucrose, and maltose; Disaccharides; urea; water-soluble alkali metal salts such as potassium chloride, sodium chloride, sodium sulfate, potassium sulfate, sodium nitrate, and potassium nitrate; selected from the group consisting of water-soluble resins such as polyvinyl alcohol and polyethylene glycol (PEG) One or a combination of two can be used. In these, water or warm water can be used as a solvent. In the case of warm water, it is preferable to increase the solubility to a temperature at which the polymer substance does not drip and increase the solubility. Depending on the polymer substance, boiling hot water may be used. In view of thermal efficiency, hot water in the range of 35 to 90 ° C, preferably 35 to 85 ° C, more preferably 40 ° C to 65 ° C is economically useful.

  It is particularly preferable that the pore forming agent is pentaerythritol containing impurities. First, since pentaerythritol is water-soluble, water can be selected as the solvent used in the washing step. Secondly, since pentaerythritol is rapidly solidified, the cooling time of the solid molded product can be shortened and the productivity is excellent. Thirdly, pentaerythritol containing impurities melts at 180 to 270 ° C., depending on its purity, but the selection range of the polymer substance is wide. For example, pentaerythritol produced for industrial use contains tripentaerythritol and dipentaerythritol as impurities, so the melting points of the respective pure compounds (pentaerythritol 269 ° C., tripentaerythritol 250 ° C., dipentaerythritol 223 ° C.) It can begin to melt at a lower temperature (approximately 180 ° C., depending on purity).

  The blending amount of the pore forming agent in the molding material can be appropriately selected according to the porosity of the porous body to be produced. That is, in the production method of the present invention, since the pore forming agent is eluted and the portion where the pore forming agent was present becomes pores, the volume ratio of the pore forming agent in the solid molded product corresponds to the porosity. become. In order to produce a porous body having a porosity of 40% or more, particularly a useful porosity of 50% or more, the pore-forming agent is used in an amount of 40 to 99% by volume, particularly 50 to 99% by volume, and more preferably 60%. The quantity which becomes -95 volume% is mix | blended. When the amount of the pore-forming agent is less than 50% by volume, the pore-forming agent contained in the solid molded product is discontinuous, and the pore-forming agent can be sufficiently extracted in the pore-forming agent removal step. Disappear.

  When pentaerythritol is used as the pore forming agent, the pore forming agent is preferably 50% by volume or more of the solid molded body. When the porosity is less than 50% by volume, even if the pore-forming agent is homogeneously dispersed in the polymer material, the pore-forming agent exists discontinuously, making it difficult to obtain a porous body having communication holes.

  As described above, the pore forming agent may be used in combination of two or more. As the pore forming agent, for example, a first pore forming agent that melts at the kneading temperature and a second pore forming agent that does not melt at the kneading temperature can be included. As a result, the pore diameter of the pore-forming agent that does not melt remains in the width of the communication hole, so that the shape of the communication hole can be easily controlled.

  The particle size of the granular pore forming agent used in the present invention can be appropriately used according to the diameter of the communication hole, but the average particle size is usually 0.1 μm to 3 μm, preferably 0.5 μm to 500 μm. It is. As described above, it is preferable to use a combination of two or more of these.

1.3 Other Additives The molding material used in the method of the present invention may further include a deterioration inhibitor, a plasticizer, a heat stabilizer, a lubricant, a thickener, a flame retardant, an antioxidant, and an ultraviolet absorber as necessary. Additives such as a colorant, a colorant, a pigment, an antistatic agent, and a reinforcing agent may be added. In the molding material used in the method of the present invention, glass fiber may be used as a means for reinforcing the shape or making it flame-retardant. In addition, in order to increase heat conduction, metal particles, magnetic particles, and various inorganic or organic fine particles as necessary can be used as additives. These additives are preferably those that do not dissolve in the solvent. If it is eluted in the elution step, it cannot remain in the porous body and cannot serve as an additive. These additives are preferably added in an amount of 50 parts by mass or less with respect to 100 parts by mass of the polymer substance.

  In addition, when the polymer substance is a thermosetting resin or rubber, it can be crosslinked by dynamic crosslinking or thermal reaction, but if necessary, a vulcanizing agent, a vulcanization accelerator, a curing agent, a crosslinking agent. Or the like can be added as a crosslinking compound.

2. Next, a manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.

  The method for producing a porous body according to the present invention comprises a kneading step of kneading a polymer substance, a pore forming agent, and an additive added as necessary, and a molding material homogeneously mixed in the kneading step in a desired shape. A forming step of obtaining a solid molded body by molding and a removing step of forming pores by mainly eluting the solid molded body using a solvent that does not dissolve the polymer substance but dissolves the pore forming agent. Including. Hereinafter, each step will be described in detail.

2.1 Kneading step The kneading step is a combination of the above-mentioned polymer substance and pore-forming agent, and additives as necessary, such as oven roll, kneader, intensive mixer, single screw extruder, twin screw extruder, etc. This is a step of kneading using an apparatus and mixing the particulate pore-forming agent in a polymer material in a uniform dispersion state.

  When a thermoplastic resin or a thermoplastic elastomer is used as the polymer substance, the temperature during kneading is preferably set to the molding temperature of the solid molded body or lower. When kneaded at a temperature at which the melting rate of the pore-forming agent is higher than necessary, the shape of the pore-forming agent is impaired, and the object of the present invention to produce a homogeneous porous body by using the pore-forming agent can be achieved. Disappear.

  When a thermosetting resin or rubber is used as the polymer material, kneading is performed at a temperature sufficiently lower than the reaction temperature so that the crosslinking agent and vulcanizing agent do not react. It is preferable to set a temperature that is 50 ° C. lower than the reaction temperature.

2.2 Molding process The molding process involves molding the molding material in which the solid pore-forming agent is maintained in a particle state and mixed in a polymer material in a uniform dispersion state in the kneading process to a desired shape. This is a process for obtaining a solid molded body.

  The molding temperature is a temperature at which a polymer substance can be molded, and a part of the pore-forming agent is melted and the melted portion communicates, and a melt viscosity suitable for the molding method is obtained. Here, the temperature at which the polymer substance can be molded varies depending on the type of the polymer substance. However, when the polymer substance is a thermoplastic resin or a thermoplastic elastomer, the temperature is such that the polymer substance melts. In the case of a curable resin or rubber, it is a temperature at which crosslinking starts, and a temperature range of 100 to 300 ° C. is generally preferably used. In the molding process of solid moldings, part of the pore-forming agent contained in the molding material melts and contributes to viscosity reduction at the temperature at which the melted part communicates, so it is lower than the molding temperature of the polymer substance alone. Temperature is set.

  Although it does not specifically limit as a method of shape | molding a solid molded object, For example, compression molding, transfer molding, injection molding, extrusion molding, blow molding, calendar processing, casting, etc. are mentioned. When a thermoplastic resin or a thermoplastic elastomer is used as the polymer material, injection molding or extrusion molding is preferably used from the viewpoint of productivity.

  The injection molding or extrusion molding conditions may be appropriately determined depending on the type and amount ratio of the polymer substance and pore forming agent to be used. For example, the delivery pressure, injection speed, etc. are set as follows. be able to.

  In general, the screw rotation speed is preferably 30 rpm or more so that the molding material is supplied without excess or deficiency. If the rotation is too fast with a low back pressure, air may be involved in the molding material, and bubbles may be generated in the solid molded body. In addition, the molding material is metered stably by applying pressure to the hydraulic cylinder during screw rotation. In general, the applied pressure is preferably in the range of 0.5 to 1.0 MPa. The injection speed in the filling process is preferably set higher when the molded body is thin, and lower when the molded body is thick. The holding pressure in the pressure holding process is set lower than the pressure at the time of filling, but the shrinkage of sink marks (sink marks) due to cooling solidification is small in the thin molded body, so the shrinkage amount is large in the low pressure, and in the thick molded body, the shrinkage is large. Shrinkage tends to occur and it is necessary to use a relatively high pressure. The lower the mold temperature, the faster the cooling rate and the higher the productivity. However, due to the decrease in fluidity, poor filling may occur and the gloss of the molded product surface may decrease. The mold temperature may be determined as appropriate based on the type of polymer substance.

  The solid molded body produced as described above is in a state in which a part of the pore-forming agent is melted while maintaining a state where a part of the pore-forming agent is dispersed in the form of particles, and the pore-forming agent particles are connected in the molten part. Alternatively, the pore-forming agent is melted once and stretched and connected in a molten state, and the pore-forming agent is molded in a continuous state in the polymer material.

2.3 Removal Step The removal step is a step of forming pores by washing the solid molded body using a solvent that does not dissolve the polymer substance but dissolves the pore-forming agent. The elution step is mainly a step of forming pores by washing the solid molded body using a solvent that does not dissolve the polymer substance but dissolves the pore forming agent. By this removal step, the pore forming agent contained in the solid molded body is dissolved in the solvent and eluted. First, the pore-forming agent present on the surface of the solid molded body is eluted, and the solvent gradually permeates into the solid molded body from the recess formed thereby, so that the pore-forming agent present in the solid molded body. Is eluted. In this way, by removing the pore-forming agent, continuous pores can be formed, and a porous body having a communication hole can be produced.

  The solvent is appropriately selected depending on the kind of the polymer substance and pore-forming agent. For example, water, glycol, glycol ether, high molecular weight alcohol, fatty acid, fatty acid ester, glycol ester, mineral oil, petroleum, alcohol ethoxylate, polyoxyethylene ester Glycerol, glycerol esters and the like. When an organic solvent or the like is used as a solvent, ancillary equipment such as post-treatment is required. Therefore, it is desirable to select a pore-forming agent that can use water that does not require such equipment as a solvent. When polyhydric alcohol, sugar, water-soluble metal salt, urea, or water-soluble polymer is used as the pore forming agent, water can be used as the solvent.

  In the removal step according to the present invention, the following method can be selected according to the physical properties and chemical properties of the polymer substance constituting the skeleton of the porous body.

(1) High-pressure steam method The high-pressure steam method is, for example, in the case of a solid molded body in which water can be used as a solvent, and sprayed onto the surface of the solid molded body with high-pressure steam that has reached 110 to 170 ° C. In this method, the pore-forming agent is melted and dissolved in water and extruded or wiped off with gas pressure. This method can be preferably used when the heat resistance of the polymer material is high, and is not significantly affected by the hardness of the polymer material. The polymer substance having high heat resistance may be any substance that does not soften or deform at the temperature of the high-pressure steam used. Specifically, it is preferably used for a polymer material whose softening point is higher than the temperature of high-pressure steam. Nylon resin, epoxy resin, polypropylene resin, polyethylene resin, polyester resin, silicone resin, resin silicone rubber such as fluororesin, and rubber polymer material such as fluororubber can be preferably used.

  In addition, when it can be easily melted by heat, high-pressure hot air can be used in place of the high-pressure steam, and the method is similar to high-pressure steam in terms of heat and external force. After the pore-forming agent is roughly removed by this method to increase the specific surface area, the pore-forming agent can be removed with high efficiency by combining other methods.

(2) Ultrasonic immersion method The ultrasonic immersion method is a method of removing the pore forming agent while immersing the solid molded body in a solvent and irradiating ultrasonic waves. This method can be applied to any polymer material, but can be particularly preferably used when the polymer material is a material that does not absorb ultrasonic waves. The material that does not absorb ultrasonic waves preferably has a Shore hardness measured by D type of 15 or more, and examples thereof include thermoplastic resins such as silicone resin, polypropylene, and polycarbonate, thermosetting resins, and thermoplastic elastomers. it can.

  An apparatus for irradiating ultrasonic waves may be any apparatus that generates cavitation in a solvent. Cavitation generated by ultrasonic irradiation bursts during high-pressure waves and generates shock waves. By this shock wave, the pore forming agent can be removed from the surface or inside of the solid molded body in a short time.

  In the ultrasonic immersion method, it is preferable to add a surfactant to the solvent. The surfactant forms a molecular assembly such as a micelle or vesicle in a solvent, and has a function as a cleaning aid that dissolves a pore-forming agent inside the molecular assembly. As the surfactant, at least one selected from an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be used.

(3) Submerged pressurization method The submerged pressurization method is a method of removing the pore forming agent while applying a physical external force to the solid molded body using a pressurizing member in a solvent. Specifically, there can be mentioned a method in which a solid molded body is sandwiched and pressurized using a pressure roll in a solvent, or a method in which a solid molded body is sandwiched and pressed between mesh plates in a solvent.

  This method can be particularly preferably used when the polymer substance is a material having rubber elasticity. The material having rubber elasticity means a material having a Shore hardness measured by D type of less than 15, for example, synthetic rubber such as silicone rubber, fluorine rubber, ethylene-propylene-diene terpolymer (EPDM). be able to. In particular, it is suitably used for solid molded articles using vulcanized rubber, and is preferably used for solid molded articles using a polymer substance having a hardness of 20 to 90, preferably 30 to 80, with an A type durometer. Moreover, since pressurization is repeated, some materials are not suitable. For example, in the case of urethane, sag appears and is not very suitable for this method.

  FIG. 1 is an apparatus diagram used in a method in which a solid molded body is sandwiched and pressurized in a solvent by a pressure roll. The apparatus includes a bathtub 20, pipes 30 and 32, and two rolls 40. The bathtub 20 can supply the solvent 12 from the pipe 30 and can discharge the solvent after the extraction process from the pipe 32. The two rolls 40 are installed inside the bathtub 20, and the width between the rolls and the rotation speed of the rolls can be arbitrarily set by driving means (not shown).

  In this method, first, the solvent 12 is supplied to the bathtub 20 so that at least the solid molded body 10 is covered with the solvent 12. Next, the two rolls 40 are passed while pressing so that the compression ratio of the solid molded body 10 is about 2 to 30% (it can be 0% at the start). Thereafter, the two rolls 40 are repeatedly passed while gradually reducing the width between the rolls and applying pressure. Finally, press molding is performed until the compression ratio of the solid molded body is about 40 to 90% according to the elastic modulus and porosity of the polymer substance, and then the solid molded body is repeatedly passed between the two rolls 40. The pore forming agent can be removed from the body 10 in a short time. When vulcanized rubber having excellent elasticity is used, it can be washed by being compressed until the communication hole is crushed 100%. Moreover, the extraction time of a pore forming agent can be further shortened by always supplying pure solvent from the pipe 30 and constantly discharging and circulating the solvent after the extraction treatment from the pipe 32.

  FIG. 3 is an apparatus diagram used in a method in which a solid molded body is sandwiched and pressurized in a solvent by a pair of mesh plates. The apparatus includes a bathtub 22, pipes 34 and 36, and a pair of mesh plates 50. The bathtub 22 can supply the solvent from the pipe 34 and can discharge the solvent after the extraction process from the pipe 36. The pair of mesh plates 50 is installed inside the bathtub 22 and, for example, one or both of the mesh plates can be moved up and down by driving means (not shown).

  In this method, first, the solvent 12 is supplied to the bathtub 22 so that at least the solid molded body 10 is covered with the solvent 12. Next, the pore forming agent can be removed from the solid molded body 10 in a short time by repeatedly pressing the solid molded body 10 using a pair of mesh plates 50. Further, the extraction time of the pore-forming agent can be further shortened by always supplying pure solvent from the pipe 34 and constantly discharging the solvent after the elution treatment from the pipe 36 or circulating it until a certain amount is eluted. it can. When the solid molded body is irregularly shaped, it is preferable to pressurize the mesh plate in accordance with its outer shape.

  The above method (1) or (2) is particularly effective when used in the first stage of removing the pore-forming agent from the solid molded body.

  Further, in the above method, one or more of them may be combined in any manner depending on the physical properties and chemical properties of the polymer material constituting the skeleton of the porous body. For example, when removing pentaerythritol from a solid molded article containing silicone rubber as a polymer substance and pentaerythritol containing impurities as a pore forming agent, first, most of the pentaerythritol was removed by ultrasonic immersion in warm water. Thereafter, the pentaerythritol can be completely removed in a short time by repeatedly passing the pressure roll in warm water.

  A porous body having a porosity of 60% or more with a relatively large communication hole diameter (specifically, an average particle diameter of a pore forming agent appearing on a plane of an arbitrarily provided cross section of the porous body is 100 μm or more) is produced. In the case of a solid molded body using a heat-resistant polymer material, the pore-forming agent such as pentaerythritol is removed by a high-pressure steam method to form pores, and then subjected to ultrasonic or liquid pressurization. When combined, the area of contact with the solvent is large, so the pore forming agent can be efficiently removed.

  In the removal step of the present invention, when the above means (1) to (3) are used in combination, the pore-forming agent can be further efficiently removed in a short time.

  In solid molded products that are resistant to high-pressure steam temperatures, such as silicone resin, polypropylene resin, fluororesin, epoxy resin or silicone rubber, fluororubber, use a means to apply high-pressure steam. After roughly removing the pore-forming agent and increasing the specific surface area, using a means for repeatedly applying pressure to the solid molded body using an ultrasonic irradiation means or a pressure member in a solvent in which the pore-forming agent dissolves Good.

  Further, in a solid molded body using an elastic body such as rubber as a polymer substance, ultrasonic waves are applied to the solid molded body in a means for applying high-pressure steam to the solid molded body or in a solvent in which a pore-forming agent is dissolved. After the pore-forming agent is removed from the surface layer of the solid molded body by means of irradiation to form part of the pores, the solid molded body is pressurized using a pressure member in a solvent in which the pore-forming agent dissolves. Pressurization can be smoothly carried out by using the means for repeated operation.

  After removing the pore-forming agent from the solid molded body by the above methods (1) to (3) or a combination thereof, finally, the obtained pore body is ultrasonically irradiated or conventionally extracted or washed using a clean solvent. It is preferable to provide a process for

The porous body produced as described above has a high porosity of 40 to 99, preferably 50 to 95% by volume, more preferably 60 to 95% by volume, in relation to the content of the pore forming agent. When the porosity is less than 40% by volume, it is not preferable because a portion where a communication hole cannot be formed is likely to occur. When the porosity exceeds 99% by volume, breakage portions are easily generated in some places, and the integrity of the entire porous body is easily lost. Although it depends on the type of polymer substance, the porous body in the present invention is a lightweight porous body having a density of 0.1 to 0.6 g / cm ³ and is suitably used as a buffer material, a heat insulating material, and various filters. Can do. Further, since the porous body produced by the production method of the present invention is a porous body having communication holes, it has excellent air permeability, and the pore forming agent contained in the molding material is substantially eliminated in the washing step. Since it is removed, it can be used for earplugs and cosmetic puff materials that require sanitary and safety to the human body. Furthermore, when glass fiber etc. are mix | blended as an additive, it can also contribute to the reinforcement | strengthening of a porous body, and a flame retardance.

3. Examples Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto.

3.1 Examples 1-4 and Comparative Examples 1-4
[Preparation of sample]
As polymer materials, 90 parts by mass of a styrene elastomer (“Hibler 7125” manufactured by Kuraray Co., Ltd.), 10 parts by mass of polypropylene (“Sumitomo Mitsui Polypro S131” manufactured by Sumitomo Mitsui Polyolefin Co., Ltd.), and acrylic-modified PTFE (“Metabrene A3000” Mitsubishi) 5 parts by mass of Rayon Co., Ltd., 0.5 parts by mass of antioxidant ("Irganox 1010" manufactured by Ciba Specialty Chemicals Co., Ltd.), and 1 mass of polymer acrylic lubricant ("Metablene L1000" manufactured by Mitsubishi Rayon Co., Ltd.) In addition, 350 parts by mass of pentaerythritol (“Pentalit” (manufactured by Guangei Chemical Co., Ltd.)) as a pore-forming agent was blended and mixed uniformly with a mixer, and this mixture was set at a cylinder temperature of 210 ° C. The mixture was kneaded using a twin screw extruder and then pelletized with a pelletizer. With Rett, injection molded by setting the cylinder temperature 200 ° C., to produce a sheet-like solid compact of thickness 2 mm.

[Test method]
An experiment for removing pentaerythritol from the solid molded body obtained by the above method using an ultrasonic immersion method was performed under the conditions described in Table 1. As the extraction solvent, water or a 0.1% by volume surfactant aqueous solution was used. Tap water was used as water. As the surfactant, a commercially available kitchen surfactant (containing 37% surfactant) was used. The solid molded body used as a sample was processed so that the mass of one piece was about 2 g. As the ultrasonic cleaner, a model “BRANSONIC 12 (MODEL B-12)” manufactured by Branson Cleaning Equipment Company was used. This ultrasonic cleaner has an output of 40 W and can generate ultrasonic waves having a frequency of 37 to 47 kHz.

First, 200 mL of extraction solvent was added to a beaker, and two samples were put into the beaker. Thereafter, the beaker was immersed in an ultrasonic cleaner set to a water temperature of 25 ° C. or 60 ° C., and irradiated with ultrasonic waves for a predetermined time. After the ultrasonic irradiation, the sample was taken out and dried for 12 hours in a thermostat set at 60 ° C., and then its mass was measured. The change in mass was determined from the difference between the mass of the sample before the test and the mass after the test, and the pentaerythritol removal rate was calculated from the ratio of pentaerythritol contained in the solid molded body by the following formula (1). The results are shown in Table 1.
Removal rate of pore forming agent (%) = {(mass before test−mass after test) ÷ (mass before test × ratio of pore forming agent contained in solid molded article)} × 100 (1)

  From the results of Example 1 and Comparative Example 1, since a significant difference is observed depending on the presence or absence of ultrasonic irradiation, it can be said that ultrasonic irradiation is an effective method for removing pentaerythritol.

  From the results of Examples 3 and 4 and Comparative Examples 3 and 4, it can be said that by setting the water temperature to 60 ° C., pentaerythritol can be efficiently removed as compared with the case where the water temperature is set to 25 ° C.

  From the results of Examples 2 and 4 and Comparative Examples 2 and 4, when a surfactant was added, the removal rate of pentaerythritol increased with time, so that the surfactant was a cleaning aid for removing pentaerythritol. It can be said that it is effective.

3.2 Example 5
[Preparation of sample]
As a polymer substance, 100 parts by mass of polypropylene (“Grand Polypro J-708” manufactured by Grand Polymer), 0.5 parts by mass of an antioxidant (“Irganox 1010” manufactured by Ciba Specialty Chemicals), and pore formation As an agent, 350 parts by mass of pentaerythritol (“Pentalit” manufactured by Guangei Chemical Co., Ltd.) is uniformly mixed with a mixer, the mixture is kneaded using a twin screw extruder set at a cylinder temperature of 220 ° C., and then pelletized with a pelletizer. Turned into. Using the produced pellets, a cylinder temperature of 220 ° C. was set for injection molding to produce a sheet-like solid molded body having a thickness of 2 mm.

[Test method]
The solid molded body obtained by the above method was immersed in an ultrasonic cleaner with a water temperature set to 60 ° C., and was irradiated with ultrasonic waves for 6 hours. As the ultrasonic cleaner, a model “BRANSONIC 12 (MODEL B-12)” manufactured by Branson Cleaning Equipment Company was used. After the ultrasonic irradiation, the porous body in which the communication holes were formed was further washed while being pressurized with warm water, thereby obtaining a porous body having a pore forming agent removal rate of 70.5%.

  Compared with Example 3, the removal efficiency of the pore forming agent was slightly inferior. The reason is that polypropylene is difficult to wet with water and hardly swells when immersed in an ultrasonic cleaner.

3.3 Example 6
[Preparation of sample]
As a polymer substance, 100 parts by mass of silicone rubber (“SH-851U” manufactured by Toray Dow Corning) and 2 parts by mass of a peroxide vulcanizing agent (“RC-4 50” manufactured by Toray Dow Corning) are blended. A silicone rubber compound was prepared by mixing and dispersing with two rolls. 110 parts by mass of a silicone rubber compound containing a vulcanizing agent, 390 parts by mass of trimethylolpropane (“Trimethylolpropane” manufactured by Mitsubishi Gas Chemical Company), and pentaerythritol (“Pentalit” manufactured by Kouei Chemical Co., Ltd.) as a pore-forming agent A rubber composition in which the pore-forming agent was dispersed was obtained by kneading for 10 minutes with a kneader set at 110 ° C. The obtained rubber composition was compression-molded in a press mold at a vulcanization temperature of 170 ° C. for 10 minutes to produce a sheet-shaped solid molded body having a thickness of 2 mm.

[Test method]
A pore forming agent removal rate of 66.1% is obtained by washing for 15 minutes while pressurizing with high-pressure steam reaching 180 ° C. from one side of the block-shaped solid molded body obtained by the above method. I was able to get a body. It can be seen that the pore-forming agent can be removed efficiently in a short time compared to Example 3 or Example 4.

3.4 Example 7
[Preparation of sample]
As a polymer substance, 100 parts by mass of silicone rubber (“SH-851U” manufactured by Toray Dow Corning) and 2 parts by mass of a peroxide vulcanizing agent (“RC-4 50” manufactured by Toray Dow Corning) are blended. A silicone rubber compound was prepared by mixing and dispersing with two rolls. 110 parts by mass of a silicone rubber compound containing a vulcanizing agent, 390 parts by mass of trimethylolpropane (“Trimethylolpropane” manufactured by Mitsubishi Gas Chemical Company), and pentaerythritol (“Pentalit” manufactured by Kouei Chemical Co., Ltd.) as a pore-forming agent A rubber composition in which the pore-forming agent was dispersed was obtained by kneading for 10 minutes with a kneader set at 110 ° C. The obtained rubber composition was compression-molded in a press mold at a vulcanization temperature of 170 ° C. for 10 minutes to produce a sheet-shaped solid molded body having a thickness of 2 mm.

[Test method]
The sheet-like solid molded body obtained by the above method is passed through the roll while being pressurized using a roll machine installed in 60 ° C. warm water so that the compression ratio of the solid molded body is about 10%. I let you. Thereafter, the roll was passed repeatedly while gradually applying pressure. Ultimately, a porous body with a pore forming agent removal rate of 90.8% can be obtained by passing the roll while pressing until the compression ratio of the solid molded body is about 40%. did it.

3.5 Example 8
[Preparation of sample]
In the same manner as in Example 7, a ridge-shaped solid molded body having a mountain height (maximum thickness) of 50 mm, a mountain ridge height (minimum thickness) of 20 mm, a flat bottom, a width of 80 mm, and a length of 150 mm. Obtained.

[Test method]
First, the obtained solid molded body was subjected to ultrasonic cleaning in warm water at 60 ° C. for 20 minutes. After that, the solid molded body is sandwiched between the upper net and the flat lower net along the almost mountain-shaped mountain, and the pressure, decompression release, and restoration of the molded body are repeated while gradually increasing the compression rate from 5% compression rate, Finally, the compression rate was increased to 50% and washing was performed for 30 minutes. Thereby, a porous body having a porosity of 60% could be obtained.

  Ultrasonic cleaning produces an elastic deformable part in the surface layer of the solid molded body, and then pressurization with the halftone plate is repeated, so there is no mechanical damage to the solid molded body and it exists in the center of the molded body Pentaerythritol can be removed. The removal rate of the pore forming agent was 98.8%.

3.6 Example 9
The solid molded body produced in Example 8 was cleaned by two cleaning methods, ultrasonic alone and pressurized in liquid. In either case, the pore-forming agent was removed at a much higher rate than in the conventional extraction method, but it took an example time to reach the same pentaerythritol removal rate as in Example 8. With ultrasonic alone, pentaerythritol remained in the center of the solid molded body, and the removal rate did not reach 90%. In the cleaning method using liquid pressure alone, the pressure points were concentrated on a part of the initial solid molded body, and the surface was damaged by a metal mesh.

3.7 Example 10
[Preparation of sample]
As a polymer substance, 100 parts by mass of polyethylene terephthalate (“Dianite KR-360” manufactured by Mitsubishi Rayon Co., Ltd.) and 20 parts by mass of micro glass fiber (“# 108A” manufactured by SCHULLER Co., Ltd.) having an average fiber diameter of 1.0 μm as a reinforcing material And 5 parts by mass of acrylic-modified PTFE (“Metabrene A3000” manufactured by Mitsubishi Rayon Co., Ltd.), 0.5 parts by mass of an antioxidant (“Irganox 1010” (manufactured by Ciba Specialty Chemicals)), and a polymer acrylic lubricant 1 part by weight (“METABBRENE L1000” manufactured by Mitsubishi Rayon Co., Ltd.) and 270 parts by weight of pentaerythritol (“Pentalit” manufactured by Guangei Chemical Co., Ltd.) as a pore-forming agent are uniformly mixed with a mixer, and this mixture is subjected to biaxial extrusion. Using a machine, the mixture was kneaded at a cylinder temperature of 230 ° C. and then pelletized with a pelletizer. The pellets were injection molded cylinder temperature 230 ° C. was used to prepare a sheet-like solid compact of thickness 2mm while removing.

[Test method]
The pentaerythritol on the surface was washed for 10 minutes while being pressurized with high-pressure steam reaching 110 ° C. from one side of the sheet-like solid molded body obtained by the above method, and then in a warm water of 60 ° C. By adding 1% by volume of an amphoteric surfactant aqueous solution (containing 37% of a surfactant) and irradiating with ultrasonic waves, a porous body having a pore formation agent removal rate of 97.1% could be obtained. It can be seen that the pore-forming agent can be removed efficiently in a short time compared to Example 3 or Example 4. The sheet was slightly deformed but was within the usable range.

FIG. 3 is an apparatus diagram used in a method in which a solid molded body is sandwiched and pressurized in a solvent by a pressure roll. FIG. 3 is an apparatus diagram used in a method in which a solid molded body is sandwiched and pressurized in a solvent by a pair of mesh plates.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Solid molded object, 12 ... Extraction solvent, 20 * 22 ... Bathtub, 30 * 32 * 34 * 36 ... Piping, 40 ... Pressure roll, 50 ... Net board

Claims (6)

A communicating hole including a kneading step of dispersing a pore-forming agent in a polymer substance to form a molding material, a molding step of molding a solid molded body from the molding material, and a removing step of removing the pore-forming agent from the solid molded body In a method for producing a porous body having
A method for producing a porous body, wherein the removing step includes at least one of the following means (1) to (3).
(1) Means for applying high-pressure steam to the solid molded body.
(2) Means for irradiating the solid molded body with ultrasonic waves in a solvent in which the pore-forming agent is dissolved.
(3) Means for repeatedly applying pressure to the solid molded body using a pressure member in a solvent in which the pore-forming agent is dissolved. In claim 1,
The method for producing a porous body, wherein the pore forming agent is pentaerythritol containing impurities. In claim 1 or 2,
The method for producing a porous body, wherein the solvent is water or warm water. In any one of Claims 1 thru | or 3,
Furthermore, the manufacturing method of a porous body which adds surfactant in the said solvent. In claim 1,
The polymer substance is a silicone resin, a polypropylene resin, a fluororesin, an epoxy resin, a silicone rubber or a fluororubber, and a solvent in which a pore-forming agent dissolves after using means for applying high-pressure steam to the solid molded body A method for producing a porous body, wherein means for repeatedly pressing the solid molded body using ultrasonic means or a pressure member is used. In claim 1,
The polymer substance is rubber, and after the means for applying high-pressure steam to the solid molded body or the means for irradiating the solid molded body with ultrasonic waves in a solvent in which the pore-forming agent is dissolved, pore formation is performed. A method for producing a porous body using means for repeatedly applying pressure to a solid molded body using a pressure member in a solvent in which the agent dissolves.

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