JP6316639B2 - Method for producing continuous pore structure - Google Patents

Description

The present invention relates to a method for producing a continuous pore structure.

Continuous pore structures are widely used in printing materials, cosmetic puffs and other applications.
As a conventional method for producing a continuous pore structure, a wet or dry method is used to form a resin molded body in which a water-soluble pore molding material is mixed and dispersed, and then the pore molding material is dissolved and extracted with water. Then, there is one that produces a continuous pore structure by removing it from the resin molding.

In the wet method, thermoplastic polyurethane is dissolved in an organic solvent, and water-soluble pore molding material is mixed and mixed. After molding into a predetermined shape, the pore molding material and organic solvent are extracted with water and removed. (Patent Document 1).
In the dry method, a room temperature solid thermoplastic elastomer and a water-soluble pore molding material are heat-kneaded and then formed into a molded body by extrusion molding or the like, and the molded body is immersed in water to extract the pore molding material. This is a removal method (Patent Document 2).

  However, the conventional wet method has a problem in the treatment of organic solvents used in large quantities. On the other hand, in the conventional dry method, the produced continuous pore structure is non-crosslinked, so that it is easily melted or deformed during high-temperature processing such as laser processing, and processing accuracy is poor and heat resistance is low.

Japanese Patent Laid-Open No. 52-32971 JP 2006-104436 A

The present invention has been made in view of the above, the organic solvent is not necessary to be added in order to mix the material, and heat resistance and compression set to provide a method for producing a good continuous pore structure Objective.

The invention according to claim 1 is a mixture obtained by mixing a liquid block polyisocyanate in which isocyanate groups are blocked with a heat dissociable blocking agent, a pore molding material comprising particles of a water-soluble inorganic salt, and an active hydrogen compound. The formed molded body is heated to crosslink and cure to form a crosslinked molded body, and the crosslinked molded body is immersed in water to extract and remove the pore molding material from the crosslinked molded body. The present invention relates to a method for producing a continuous pore structure characterized by being a structure.

The invention of claim 2 is characterized in that, in claim 1 , the second active hydrogen compound is further mixed with polyethylene glycol which is an active hydrogen compound.

According to invention of Claim 1 , while being able to solve the problem of an organic-solvent process, a continuous pore structure with favorable heat resistance and compression set can be manufactured.

According to the invention of claim 2 , by adding polyethylene glycol as the second active hydrogen compound, the compression set of the continuous pore structure can be further improved (compression set is reduced).

It is a perspective view of the continuous pore structure concerning one embodiment of the present invention. It is a figure which shows the example of a hot press.

  A continuous pore structure 10 according to one embodiment of the present invention shown in FIG. 1 is a crosslinked molding obtained by crosslinking and curing a molded product of a mixture obtained by mixing block polyisocyanate, a pore molding material, and an active hydrogen compound. The pore forming material is extracted and removed from the body with water to form a continuous pore structure, and in the illustrated example, it is formed into a sheet shape. The continuous pore structure means a structure in which internal pores communicate with each other and are opened on the outer surface of the continuous pore structure 10.

  The block polyisocyanate used in the present invention is a block polyisocyanate (hereinafter also referred to as block polyisocyanate) in which a terminal isocyanate group is blocked (capped) with a heat dissociable blocking agent, and is liquid at normal temperature (as defined in JIS-Z8703). Any of 20 ° C., 23 ° C., or 25 ° C., either 50% or 65% relative humidity, and liquid at atmospheric pressure of 86 Pa or more and 106 kPa or less. When the blocked polyisocyanate is mixed with an active hydrogen compound at room temperature, the isocyanate group blocked with the blocking agent does not react and is heated (for example, heated to 140 to 160 ° C. when blocked with butanone oxime). As a result, the blocking agent is dissociated, and the exposed isocyanate group reacts with the active hydrogen compound to crosslink and cure.

  The block polyisocyanate used in the present invention preferably has a viscosity at 23 ° C. of 7,000 to 120,000 mPa · s, more preferably 50,000 to 90,000 mPa · s. The viscosity was measured using an E-type viscometer.

The block polyisocyanate used in the present invention is obtained by reacting a polyisocyanate having an isocyanate group at a terminal with a thermally dissociable blocking agent.
The polyisocyanate used for the production of the block polyisocyanate is aliphatic diisocyanate or alicyclic diisocyanate or aromatic isocyanate alone or a mixture thereof, and polyester polyol, preferably polycaprolactone polyol or polyether polyol alone, Or it is obtained by making it react with those mixtures.

  Examples of thermally dissociable blocking agents include oxime compounds such as formaldoxime, acetoaldoxime, acetoxime, and methylethylketoxime, pyrazole compounds such as pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole, acetoacetamide, and the like Amide compounds such as diphenylamine, aniline and carbazole, active methylene compounds such as diethyl malonate and dimethyl malonate, alcohol compounds such as methanol, ethanol and 2-propanol, acetanilide, acetic acid amide, ε- Examples thereof include acid amide compounds such as caprolactam, acid imide compounds such as succinimide and maleic imide, and phenol compounds such as phenol, cresol and ethylphenol.

The block polyisocyanate can be produced by mixing and reacting the polyisocyanate and the heat dissociable blocking agent at -20 to 150 ° C.
Moreover, the said block polyisocyanate used by this invention can use a commercially available thing. For example, block polyisocyanate (aromatic urethane prepolymer) in which both end isocyanate groups are blocked with butanone oxime (aromatic urethane prepolymer), product name: Impranil HS-62, manufactured by Bayer, or product name: Urehyper CRU-5100, manufactured by DIC Corporation Etc.

As the pore forming material, particles of a water-soluble inorganic salt are used. The water-soluble inorganic salt particles may be any inorganic substance that is soluble in water and stable at a heating temperature at which the thermally dissociable blocking agent is thermally dissociated. For example, NaCl, KCl, CaCl, NH ₄ Cl, NaNO ₃ , NaNO _{2 and the} like can be mentioned. Moreover, since the size of the pore molding material affects the formation of continuous pores of the continuous pore structure 10, the average particle size is 1 to 300 μm, preferably 80 to 200 μm, and particularly 85 to 95 μm. Those are preferred.
The mixing ratio of the block polyisocyanate and the pore molding material is preferably in the range of 10:90 to 40:60 by volume ratio. When the block polyisocyanate is less than 10 Vol%, the molded body itself is separated and a continuous pore porous body cannot be obtained. When it exceeds 60 Vol%, a sufficient number of bubbles are not formed in the molded body, making it difficult to communicate.

  As the active hydrogen compound, a compound in which two or more active hydrogens are bonded in the molecule is used. For example, a polyol compound, a polyamine compound, etc. can be mentioned. Examples of the polyol compound include polyester polyol, polyether polyol, acrylic polyol, and polyolefin polyol. Examples of the polyamine compound include ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,4-diaminocyclohexane, 4,4 "'-diaminodicyclohexylmethane, isophoronediamine and the like. The equivalent ratio of blocked NCO groups in the blocked polyisocyanate to the functional groups having active hydrogen of the active hydrogen compound used as the curing agent is preferably 1.25: 1 to 1: 1.

In addition, you may mix | blend an appropriate additive with the said mixture. As the additive, polyethylene glycol used as the second active hydrogen compound is particularly suitable. By adding polyethylene glycol, the compression set of the continuous pore structure 10 can be further improved (compression set can be reduced). The amount of polyethylene glycol added is preferably such that the volume ratio of the pore molding material to polyethylene glycol is about 45:55 to 95: 5.
Examples of other additives include an antioxidant, a pigment, and an ultraviolet absorber.

The continuous pore structure 10 is manufactured by a mixing step, a shaping heating step, and a pore forming material removing step.
In the mixing step, the block polyisocyanate, the pore forming material, the active hydrogen compound, and an appropriate additive (for example, polyethylene glycol) added as necessary are mixed in the blending amount. The mixing apparatus is not particularly limited, and examples thereof include a ribbon mixer, a planetarium mixer, a kneader, and a lab plast mill. Moreover, the said mixing is performed at normal temperature (non-heating). By the mixing, a clay-like mixture is obtained.

In the shaping heating step, the mixture obtained in the mixing step is shaped into a predetermined shape to form a molded body, and the obtained molded body is heated to be crosslinked and cured to form a crosslinked molded body. The shaping of the mixture is performed by an appropriate method such as extrusion molding or filling into a mold.
That is, in addition to a batch-type forming method using a hot press, the mixture can be continuously formed into a sheet by calendering and roll forming using a roll. Furthermore, the mixture can be filled into a mold and heated and compressed to form a desired shape, specifically, a columnar shape, a cylindrical shape, or a pyramid shape. In addition, the heating method of the molded body of the shaped mixture is not limited, and the molded body of the mixture is placed in a heating furnace and heated, or the mixture is filled in a mold and hot pressed to form and heat the molded body. May be done at once.

  FIG. 2 shows an example in the case of hot pressing using the mold 20. The mold 20 includes a lower mold 21 and an upper mold 23, and the lower mold 21 has a mixture containing portion 29 inside. The lower mold 21 and the upper mold 23 are provided with heating wires as heating means 25 and 27 and are connected to a power supply device (not shown) outside the mold 20 so as to be heated.

A predetermined amount of the mixture P is filled in the mixture containing portion 29 of the lower mold 21 heated by the heating means 25, and then the upper mold 23 heated by the heating means 27 is stacked on the lower mold 21 to form a mold. 20 is closed, and the mixture P is hot pressed by the lower mold 21 and the upper mold 23.
The mixture in the mold 20 is shaped into a shape between the lower mold 21 and the upper mold 23 (a sheet shape in the illustrated example) by the hot press to be a molded body and heated. The molded body is heated to dissociate the thermally dissociable blocking agent from the block polyisocyanate, and the isocyanate group exposed in the polyisocyanate from which the thermally dissociable blocking agent is dissociated reacts with the active hydrogen compound to crosslink and cure. Thus, a crosslinked molded body is formed.

  In addition, in the case of cross-linking after shaping with a press, it is heated at a temperature lower than the temperature at which the thermally dissociable block material dissociates and can ensure the fluidity of the mixture, and then the temperature at which the dissociable blocking agent dissociates Heat at a temperature of. For example, block polyisocyanate blocked with butanone oxime (dissociation temperature of the blocking agent, 140 ° C.) is set to a temperature of about 40-60 ° C., and then the mold temperature is raised to a temperature exceeding 150 ° C. Is preferred. In addition, when shaping and crosslinking are carried out at the same time, heating is performed at a temperature higher than the temperature at which the blocked block material is dissociated. For example, a block polyisocyanate blocked with butanone oxime is preferably heated at about 150 to 160 ° C.

  In the pore forming material removing step, the crosslinked molded body is immersed in water, and the pore molded material in the crosslinked molded body is extracted with water and removed to the outside of the crosslinked molded body. Thereby, the part from which the pore forming material has been removed communicates to form a continuous vent structure. The method of immersing the crosslinked molded body in water is not particularly limited, and examples thereof include a method of taking out the crosslinked molded body after immersing the crosslinked molded body in a water tank for a predetermined time. The crosslinked molded body taken out from the water is dried to obtain the continuous pore structure 10 of FIG.

  The continuous pore structure has an intersection of storage elastic modulus (G ′) and loss elastic modulus (G ″) in dynamic viscoelasticity measurement of 160 ° C. or higher, test temperature 70 ° C. based on JIS-K6400A method, 50 % The strain rate after compression (compression permanent strain) is 35% or less, and the extraction rate indicating the ratio of the pore molding material extracted to the pore molding material in the mixture is 95% or more.

  The temperature at the intersection of the storage elastic modulus (G ′) and loss elastic modulus (G ″) in the dynamic viscoelasticity measurement is an index of heat resistance, and the higher the temperature at the intersection, the better the heat resistance. become.

  The strain rate after 50% compression at a test temperature of 70 ° C. based on the JIS-K6400A method is an index of compression set, and the smaller the value of the strain rate after compression at a test temperature of 70 ° C. and 50%, Compression set is good.

The extraction rate can be used as an index of communication, and the larger the extraction rate, the better the communication (breathability).
The extraction rate is calculated as follows. The weight of the test piece before extraction and the weight of the test piece after drying at 70 ° C. after the extraction are measured, and the difference between the weight of the test piece before extraction and the weight of the test piece after extraction drying is measured. The ratio of the extraction amount to the weight of the pore molding material added at the time of preparing the mixture was calculated to obtain the extraction rate.

Example 1
As a blocked polyisocyanate blocked with a heat dissociable blocking agent, an aromatic urethane prepolymer capped with NCO at both ends with butane oxime, a viscosity of 70,000 mPa · s at 25 ° C., product name: Impranil HS-62, manufactured by Bayer, 27 g of an aliphatic diamine as an active hydrogen compound, 1.67 g, and 123 g of sodium chloride powder having an average particle diameter of 90 μm as a pore forming material, using a lab plast mill manufactured by Toyo Seiki Seisakusho Co., Ltd. 25 ° C.) and mixing at 50 rpm for 10 minutes to obtain a clay-like mixture. The mixture temperature during mixing was 34.3 ° C.

  The clay-like mixture was filled in a mold mixture storage section heated to 150 ° C., and hot-pressed by a closed mold for 10 minutes to form a 180 × 130 × 1.5 mm sheet-shaped crosslinked product. . In addition, the mixture accommodation part at the time of the mold closing is 180 * 130 * 1.5 mm. Even when the mold is closed, a vent is provided, and the excess mixture flows out as burrs to the outside of the mold.

  The crosslinked molded body taken out from the mold was immersed in a water tank for 24 hours, and sodium chloride as a pore molding material was extracted and removed from the crosslinked molded body. Thereafter, the crosslinked molded body was dried in an oven at 70 ° C. to obtain a continuous pore structure of Example 1.

Example 2
30 g of the block polyisocyanate of Example 1, 1.86 g of the active hydrogen compound (aliphatic diamine) of Example 1, 98 g of the pore molding material of Example 1, and 22 g of polyethylene glycol that is solid at room temperature are added. The continuous pore structure of Example 2 was obtained by mixing, filling in a mold, hot pressing, dipping in water, and drying under the same conditions as in Example 1.

Example 3
As block polyisocyanate blocked with a heat dissociable blocking agent, product name: Urehyper CRU-5100, manufactured by DIC Corporation, viscosity of 45,000 mPa · s at 30 ° C., curing agent as active hydrogen compound, CLH-1 (manufactured by DIC Corporation, A continuous pore structure of Example 3 was obtained using sodium chloride (reagent) having an average particle diameter of 90 μm as the aliphatic diamine derivative) and pore forming material, and using the same blending ratio as in Example 1.

Comparative example 1
Thermoplastic polyurethane elastomer (TPU), product name: Estran ET370-10 (pellet-shaped, solid at room temperature), BASF, 27 g, and pore molding material 123 g of Example 1 were manufactured by Toyo Seiki Seisakusho Lab. Using a plastmill, the mixture was mixed at 160 ° C. and 50 rpm for 10 minutes to form a clay-like mixture. The mixture temperature during mixing was 162 ° C.

The mixture was filled in the mixture housing part of the mold of Example 1 heated to 180 ° C., and subjected to hot pressing with a closed mold for 10 minutes to form a crosslinked molded body having a sheet shape of 180 × 130 × 1.5 mm. .
The cross-linked molded product taken out from the mold was immersed in a water tank for 24 hours, and the pore forming material was extracted and removed from the cross-linked molded product. Thereafter, the crosslinked molded body was dried in an oven at 70 ° C. to obtain a continuous pore structure of Comparative Example 1.

Comparative example 2
30 g of the thermoplastic polyurethane elastomer of Comparative Example 1 and 98 g of the pore molding material of Comparative Example 1, and further 22 g of polyethylene glycol that is solid at room temperature are added, mixed under the same conditions as in Comparative Example 1, and filled into the mold , Hot press, immersion in water and drying were performed to obtain a continuous pore structure of Comparative Example 2.

Comparative example 3
A non-crosslinked polyolefin continuous pore structure produced by a conventional dry method, product name: MAPS (ST30-50), manufactured by Inoac Corporation was used as the continuous pore structure of Comparative Example 3. In addition, Comparative Example 3 is a commercially purchased product, and the weight of the pore forming material added at the time of preparing the mixture and the weight before extraction are unknown. Therefore, ash content analysis was performed, and the sample of Comparative Example 3 was allowed to stand in an environment of 700 ° C. × 3 h, and since no residue was observed, the extraction rate was set to 100%.
Comparative example 4
A thermoplastic non-crosslinked polyurethane continuous pore structure produced by a conventional wet method, product name: Ruby Cell (density 0.15 g / cm ³ ), manufactured by Toyo Polymer Co., Ltd. was used as a continuous pore structure of Comparative Example 4. In addition, the comparative example 4 is a commercial purchase item, and the weight of the pore molding material added at the time of mixture preparation and the weight before extraction are unknown. Therefore, ash content analysis was performed, and the sample of Comparative Example 4 was allowed to stand in an environment of 700 ° C. × 3 h, and the extraction rate was set to 100% because no residue was observed.

  About the said Example and a comparative example, the temperature of the intersection of the said storage elastic modulus (G ') and a loss elastic modulus (G "), the test temperature of 70 degreeC based on JIS-K6400A method, the distortion rate after 50% compression, and extraction The rate was measured as follows, and the measurement results are shown in Table 1.

The temperature measurement at the intersection of the storage elastic modulus (G ′) and the loss elastic modulus (G ″) in the dynamic viscoelasticity measurement was performed by punching the sheet into a cylindrical shape of 8 mmφ, and using ARES manufactured by TA Instruments. The temperature dependence was measured using a parallel plate in a range of 25 to 250 ° C., a frequency of 1 Hz, a strain of 3%, and the temperature at which the storage elastic modulus (G ′) and the loss elastic modulus (G ″) intersect was obtained. .
The strain rate after 50% compression at a test temperature of 70 ° C. based on the JIS-K6400A method was measured after compressing the test piece by 50% and heating in an oven at 70 ° C. for 22 hours, and after 30 minutes, the thickness of the test piece ( The thickness after the test was measured and calculated by the formula: (thickness before the test−thickness after the test) / (thickness before the test) × 100.
The extraction rate is measured by measuring the weight of the test piece before extraction and the weight of the test piece after drying at 70 ° C. after extraction to calculate the extraction amount. This was done by calculating the proportion of quantity.

  As shown in the measurement results of Table 1, the continuous pore structure of each example has a temperature at the intersection of the storage elastic modulus (G ′) and the loss elastic modulus (G ″) as compared with the continuous pore structure of each comparative example. Since the heat resistance is high, the heat resistance is high, and the test temperature is 70 ° C. based on the JIS-K6400A method, and the strain rate after compression is small, so that the compression set is small. The continuous pore structure of Example 2 had better heat resistance and compression set than the continuous pore structure of Example 1 that did not contain polyethylene glycol. Was 95% or more, and the connectivity was good.

As described above, according to the present invention, a continuous pore structure can be produced without adding an organic solvent, and there is no problem in the treatment of the organic solvent. Furthermore, since the continuous pore structure is crosslinked, heat resistance and compression set are good.
In addition, the shape of the said continuous pore structure is not restricted to the rectangular sheet shape like an Example, It is set as the shape according to a use.

DESCRIPTION OF SYMBOLS 10 Continuous pore structure 20 Mold 21 Lower mold 23 Upper mold 25 Heating means 29 Mixture accommodating part P Mixture

Claims (2)

Mixing a liquid block polyisocyanate in which an isocyanate group is blocked with a thermally dissociable blocking agent, a pore molding material composed of water-soluble inorganic salt particles, and an active hydrogen compound,
  The molded body shaped the obtained mixture is heated to crosslink and cure to form a crosslinked molded body,
  A method for producing a continuous pore structure, wherein the crosslinked molded body is immersed in water to extract and remove the pore molding material from the crosslinked molded body to obtain a continuous pore structure. The method for producing a continuous pore structure according to claim 1, wherein the second active hydrogen compound is further mixed by adding polyethylene glycol which is an active hydrogen compound.

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