JP4019738B2 - Method for producing porous material made of thermoplastic polyurethane resin and porous material made of thermoplastic polyurethane resin - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a porous material made of a thermoplastic polyurethane resin, and a porous material made of a thermoplastic polyurethane resin produced by this method.
[0002]
[Prior art]
Porous materials made of thermoplastic polyurethane resin are used in many industries such as artificial leather and cosmetic puffs because of their excellent touch.
[0003]
Conventionally, a porous material made of a thermoplastic polyurethane resin is generally obtained by dissolving a thermoplastic polyurethane resin in a polar organic solvent such as dimethylformamide or N-methyl-2-pyrrolidone, which is a good solvent, and adding and mixing a pore-forming agent thereto. Then, after being solidified, it is produced by a so-called wet film forming method in which the good solvent and the pore-forming agent are extracted and removed. Here, water-soluble polymer compounds such as polyvinyl pyrrolidone, polyvinyl alcohol, and cellulose derivatives are widely used as pore-forming agents because the pore size can be easily controlled and a porous material having a sharp pore size distribution can be obtained. Yes.
[0004]
[Problems to be solved by the invention]
However, as a disadvantage of the wet film-forming method in which a thermoplastic polyurethane resin dissolved in a solvent is coagulated in a coagulation bath, the surface layer portion of the resulting porous material has a dense layer that is extremely different in structure or air permeability from the inside, so-called There is a problem that a skin layer is generated.
[0005]
Since this skin layer is a factor that adversely affects the air permeability of the porous material, that is, the water absorption, and the touch feeling becomes very bad, usually, the porous material on which such a skin layer is formed is the surface layer portion. The skin layer is polished or removed by slicing the skin layer and a part of the porous structure layer below the skin layer.
[0006]
However, the polishing and slicing of the skin layer can be easily performed if the target surface is a smooth plane, but in the case of a porous material having a curved surface, it is difficult to remove the skin layer or It becomes impossible. In addition, even if polishing and slicing are possible, fraying of the network structure and contamination by polishing debris are confirmed on the polished surface, and the sliced surface does not become a uniform cut surface due to friction of the blade, There was a problem that the surface was uneven. Further, there are problems in that the labor and time required for the removal process of the skin layer and the yield is reduced by discarding the removed skin layer.
[0007]
These treatments are relatively easy if the pore size of the porous material is on the order of several tens of μm. However, in the case of a porous material having a large pore size exceeding 150 μm, the porous material bites into the blade and is stable. Polishing or slicing is difficult. In order to prevent the porous material from being caught, special operations such as freezing with liquid nitrogen are required.
[0008]
The present invention solves the above-mentioned conventional problems, and without producing a dense skin layer on the surface layer portion, a method for producing a porous material made of a thermoplastic polyurethane resin having a homogeneous network structure on the entire surface, and this method An object of the present invention is to provide a porous material made of a thermoplastic polyurethane resin.
[0009]
[Means for Solving the Problems]
The method for producing a porous material made of a thermoplastic polyurethane resin according to the present invention comprises a thermoplastic polyurethane resin, an oligosaccharide and a polysaccharide having at least one α-1,4 bond and / or β-1,4 bond, and derivatives thereof. A polymer dope comprising one or more water-soluble polymer compounds selected from the group consisting of an oxygen-containing / nitrogen organic solvent containing an oxygen atom or nitrogen atom in the molecule, and a solidification containing a hydrophilic organic solvent A thermoplastic polyurethane comprising a step of immersing in a bath, extracting and removing the oxygen-containing / nitrogen organic solvent to coagulate the thermoplastic polyurethane resin, and then extracting and removing the water-soluble polymer compound and the hydrophilic organic solvent. A method for producing a resinous porous material, wherein at the time of coagulation of the thermoplastic polyurethane resin, the polymer dope is at least partially made of the hydrophilic organic solvent. It is characterized in that it is housed in a partition member capable of passing liquid and immersed in the coagulation bath.
[0010]
In the present invention, as the water-soluble polymer compound to be mixed and dispersed in the polymer dope as the pore-forming agent, the water-soluble polymer compound having low solubility in the hydrophilic organic solvent of the coagulation bath, that is, at least one α-1, One type or two or more types selected from the group consisting of oligosaccharides and polysaccharides having 4 bonds and / or β-1,4 bonds and derivatives thereof are used.
[0011]
A polymer dope in which a water-soluble polymer compound having low solubility in such a hydrophilic organic solvent is dispersed as a pore-forming agent is immersed in the hydrophilic organic solvent, and oxygen-containing / Since only the nitrogen organic solvent can be selectively extracted and removed, and the hydrophilic organic solvent can enter the site from which this good solvent has been removed, the thermoplastic polyurethane resin can be solidified while maintaining the higher order structure. Can do. Therefore, a porous material having any average pore size can be produced with a sharp pore size distribution and free from defects such as voids and pinholes.
[0012]
Therefore, in the present invention, when the thermoplastic polyurethane resin in the polymer dope is solidified in the coagulation bath, the polymer dope is accommodated in the partition member, and the partition member is placed at the interface between the polymer dope and the hydrophilic organic solvent. By interposing, a porous material without a skin layer can be easily produced.
[0013]
That is, when the thermoplastic polyurethane resin is solidified, if a partition member is interposed at the interface between the coagulation bath and the polymer dope, there is no skin layer, or the appearance is a porous material having a skin layer formed on the surface. Is obtained. Even when a porous material in which a skin layer is formed is obtained, this skin layer does not adhere to the porous body portion of the porous material and can be easily peeled off.
[0014]
The porous material made of thermoplastic polyurethane resin of the present invention is produced by the method for producing the porous material made of thermoplastic polyurethane resin of the present invention, and has a sharp pore size distribution, such as voids and pinholes. There is no defect, and there is no skin layer on the surface, and it is substantially homogeneous from the inside to the surface layer.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail according to the production procedure of the porous material made of thermoplastic polyurethane resin of the present invention.
[0016]
In the present invention, first, a polymer dope is produced by mixing a thermoplastic polyurethane resin, a water-soluble polymer compound that is a pore-forming agent, and an oxygen-containing / nitrogen organic solvent that is a good solvent for the thermoplastic polyurethane resin. . Specifically, a thermoplastic polyurethane resin is mixed with an oxygen-containing / nitrogen organic solvent to form a uniform solution, and then a water-soluble polymer compound is mixed and dispersed in this solution.
[0017]
The composition of the polymer dope is 0.2 to 90 parts by weight of a thermoplastic polyurethane resin, 0.2 to 90 parts by weight of a water-soluble polymer compound, and 0.2 to 99.6 parts by weight of an oxygen-containing / nitrogen organic solvent. (However, the total of the thermoplastic polyurethane resin, the water-soluble polymer compound and the oxygen-containing / nitrogen organic solvent is 100 parts by weight.) Particularly preferably, the thermoplastic polyurethane resin is 0.2 to 50 parts by weight. Parts, water-soluble polymer compound 0.2 to 50 parts by weight, oxygen-containing / nitrogen organic solvent 0.2 to 99.6 parts by weight, particularly preferably 0.2 to 20 parts by weight of thermoplastic polyurethane resin, water-soluble high Thermoplastic polyurethane resin porous material that is 0.2 to 20 parts by weight of a molecular compound and 60 to 99.6 parts by weight of an oxygen-containing / nitrogen organic solvent and is easily used industrially at such a blending ratio. It is possible to obtain a porous material that expressed originally excellent feel.
[0018]
In particular, the mixing ratio of the thermoplastic polyurethane resin and the water-soluble polymer compound is as follows: thermoplastic polyurethane resin: water-soluble polymer compound = 1: 0.1 to 10 (weight ratio), preferably 1: 0.1 to 2 With such a composition, the effect of stabilizing the higher-order structure of the porous material according to the present invention is effectively exhibited.
[0019]
In the present invention, the oxygen-containing / nitrogen organic solvent as a good solvent for the thermoplastic polyurethane resin is an organic solvent containing an oxygen atom or a nitrogen atom in the molecule, specifically, tetrahydrofuran, N-methylpyrrolidone, N, N -It is possible to use dimethylformamide, pyridine and simple substitutions thereof. One of these oxygen-containing / nitrogen organic solvents may be used alone, or two or more thereof may be mixed and used. In addition, the simple substituent refers to, for example, a compound in which an alkane atom is introduced into a heterocyclic ring such as 2-methylpyridine, 2-methyltetrahydrofuran, or 2-pyrrolidone, or a substance in which a hydrogen atom is introduced in the opposite direction. .
[0020]
The water-soluble polymer compound as the pore-forming agent is at least one of oligosaccharides and polysaccharides having at least one α-1,4 bond and / or β-1,4 bond, and derivatives thereof. Yes, preferably cellulose ethers such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, etc., but as long as it is homogeneously dispersed with the thermoplastic polyurethane resin and does not dissolve freely in the hydrophilic organic solvent Absent.
[0021]
A polymer dope produced from a thermoplastic polyurethane resin, an oxygen-containing / nitrogen organic solvent, and a water-soluble polymer compound is at least partially housed in a partition member through which a hydrophilic organic solvent in a coagulation bath can be passed. Then, it is immersed in a coagulation liquid containing a hydrophilic organic solvent, and the oxygen-containing / nitrogen organic solvent is extracted and removed to cause the thermoplastic polyurethane resin to coagulate.
[0022]
Examples of the hydrophilic organic solvent from which the oxygen-containing / nitrogen organic solvent is extracted include methanol, ethanol, propanol, acetone, and derivatives thereof, but are not limited thereto. These hydrophilic organic solvents may be used individually by 1 type, and may mix and use 2 or more types.
[0023]
As the partition member to be present at the interface between the polymer dope and the coagulation bath when coagulating the thermoplastic polyurethane resin, a structure composed of a metal material, a polymer material, an inorganic material, or the like can be used. Structures composed of one or more polymer materials such as polyolefin resin, polyester resin, polycarbonate resin, fluororesin, silicon resin, polyamide resin, polyimide resin, polyether ether ketone resin and polysaccharide can be used. Yes, but this is not the case. The polysaccharide includes paper, cloth, wood and the like.
[0024]
The partition member interposed at the interface is particularly preferably made of a porous material, whereby a homogeneous porous material made of thermoplastic polyurethane resin can be obtained from the inside without the skin layer to the surface layer.
[0025]
In the present invention, as such a partition member, specifically, a container having an outflow inlet through which the hydrophilic organic solvent of the coagulation bath can flow, for example, a tubular shape, a spherical shape, a conical shape, a hand shape, and a radiation (star) shape. It may be any shape such as a bowl, sheet, rod, etc., and examples include containers with complicated shapes that cannot be polished or sliced. The method of immersing in is mentioned.
[0026]
The temperature of the hydrophilic organic solvent in the coagulation bath is preferably 10 ° C. or higher. This is a temperature set in consideration of the solubility of oligosaccharides and polysaccharides having at least one α-1,4 bond and / or β-1,4 bond, and their derivatives, which are pore-forming agents, and low temperature. This is the temperature required to maintain these in the polymer dope, which is easily soluble in the polymer dope. Accordingly, the temperature of the hydrophilic organic solvent in the coagulation bath is more preferably a higher temperature, for example, 40 ° C. or higher, and is equal to or higher than the boiling temperature of the hydrophilic organic solvent at 0.1 MPa (760 mmHg), It is also preferable to perform coagulation in a reflux state.
[0027]
In extracting and removing the oxygen-containing / nitrogen organic solvent, the polymer dope and the coagulation bath can be in a reduced pressure state. Thereby, not only the hydrophilic organic solvent of the coagulation bath but also the boiling point of the good solvent of the thermoplastic polyurethane resin is lowered, and the effect of promoting the diffusion of the good solvent into the coagulation bath can be obtained.
[0028]
In this way, after the oxygen-containing / nitrogen organic solvent is extracted and solidified to solidify the thermoplastic polyurethane resin, the water-soluble polymer compound of the pore-forming agent is extracted and removed, so that the porosity of the thermoplastic polyurethane resin is increased. Material can be obtained. This extraction and removal of the water-soluble polymer compound can be easily performed using water.
[0029]
The thermoplastic polyurethane resin porous material produced from the thermoplastic polyurethane resin porous material of the present invention has an average pore diameter of 0.1 to 500 μm, preferably a wide average particle diameter of 0.1 to 200 μm. A high-quality material with a sharp pore size distribution and no defects such as voids and pinholes, and a high-quality structure with no dense skin layer on the surface and a homogeneous porous structure from the inside to the surface. It is a porous material made of thermoplastic polyurethane resin.
[0030]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
[0031]
Example 1
2. A thermoplastic polyurethane resin (produced by Nippon Milactolan, Milactolan E980PNAT) is dissolved in N-methyl-2-pyrrolidone (produced by Kanto Chemical Co., Ltd., reagent, for peptide synthesis, NMP) at room temperature using a dissolver. A 5% solution (weight / weight) was obtained. About 1.0 kg of this NMP solution was put into a planetary mixer (Inoue Seisakusho, 2.0 L charged), and methyl cellulose (made by Kanto Chemical Co., Inc., reagent, 25 cp) of the same weight as the polyurethane resin was mixed at 40 ° C. for 20 minutes. Thereafter, the pressure was reduced to 20 mmHg (2.7 kPa) for 10 minutes for defoaming to obtain a polymer dope.
[0032]
The polymer dope is filled into a polypropylene cylinder having an inner diameter of 5 mmφ and a length of 40 mm, and both ends are sealed with absorbent cotton and charged into refluxing methanol (Kanto Chemical Co., Ltd., reagent grade) for 96 hours. Refluxing continued.
[0033]
During the reflux operation, it was confirmed that methanol permeated through the absorbent cotton from both ends of the cylinder, and NMP in the polymer dope diffused from the inside, and the side peripheral surface of the cylinder over the entire surface of 40 mm in about 24 hours. Whitening was confirmed.
[0034]
After 96 hours of reflux, the absorbent cotton on both ends was removed, the solidified polymer was pulled out from the cylinder, and washed in running water for 24 hours to obtain a porous material made of thermoplastic polyurethane resin.
[0035]
A stereomicroscope (Keyence Co., VH-6300) photograph (35 times) of the surface layer portion of the obtained porous material made of thermoplastic polyurethane resin is shown in FIG. From this stereomicroscopic image, this thermoplastic polyurethane resin porous material has a skin layer on its appearance, but this skin layer is not adhered to the porous material body, and the gap should be confirmed. Can do. By pulling this skin layer with tweezers, as shown in a stereoscopic micrograph (35 times) in FIG.
[0036]
This porous material made of thermoplastic polyurethane resin was confirmed to be a porous material having an average pore size of 39 μm and having no pinholes or voids and having a homogeneous three-dimensional network structure.
[0037]
Example 2
The polymer dope prepared in the same manner as in Example 1 was poured into a 5 mmφ paper tube made of filter paper (manufactured by Toyo Roshi Kaisha, No. 2), and both ends were sealed with absorbent cotton and in a reflux state. The solution was put into methanol (Kanto Chemical Co., Inc., reagent grade) and refluxed for 48 hours. Then, after taking out and cooling, the paper tube was removed and washed in running water for 17 hours to obtain a porous material made of thermoplastic polyurethane resin.
[0038]
FIG. 3 shows a SEM (scanning electron microscope, JMS-5800LV, JEOL Co., Ltd., JMS-5800LV) photograph (500 times) of the surface layer portion of the obtained porous material made of thermoplastic polyurethane resin. From this SEM image, it was confirmed that this porous material made of thermoplastic polyurethane resin is a porous material having a three-dimensional network structure having no skin layer and having a homogeneous and similar structure from the surface layer to the inside. The porous material made of thermoplastic polyurethane resin had an average pore diameter of 169 μm and no pinholes or voids.
[0039]
Comparative Example 1
A porous material made of a thermoplastic polyurethane resin was obtained in the same manner except that the polymer dope prepared in the same manner as in Example 1 was put in a paper plate and put into methanol in this state.
[0040]
The obtained porous material made of thermoplastic polyurethane resin was porous inside, but a dense skin layer having a thickness of 10 μm was formed on its surface (surface opposite to the paper plate contact surface). . Although this skin layer was tried to be removed by polishing with a precision grinder equipped with a diamond blade, it could not be completely removed, and inhomogeneous portions such as uneven polishing were generated.
[0041]
【The invention's effect】
As described above in detail, according to the method of the present invention, it has a good higher-order structure in various hole diameters, has a sharp hole diameter distribution, is free from defects such as voids and pinholes, and substantially from the inside to the surface layer. It is possible to stably and efficiently produce a porous material made of a thermoplastic polyurethane resin that is homogeneous, thereby providing a low-quality porous material made of a thermoplastic polyurethane resin.
[Brief description of the drawings]
1 is a stereomicrograph of a surface layer portion of a porous material made of a thermoplastic polyurethane resin produced in Example 1. FIG.
2 is a stereomicrograph of a surface layer portion after peeling a skin layer of a porous material made of a thermoplastic polyurethane resin manufactured in Example 1. FIG.
3 is a SEM photograph of a surface layer portion of a porous material made of a thermoplastic polyurethane resin produced in Example 2. FIG.

Claims (12)

A thermoplastic polyurethane resin;
One or more water-soluble polymer compounds selected from the group consisting of oligosaccharides and polysaccharides having at least one α-1,4 bond and / or β-1,4 bond, and derivatives thereof;
A polymer dope containing an oxygen-containing / nitrogen organic solvent containing oxygen atoms or nitrogen atoms in the molecule is immersed in a coagulation bath containing a hydrophilic organic solvent, and the oxygen-containing / nitrogen organic solvent is extracted and removed. A method for producing a porous material made of a thermoplastic polyurethane resin comprising a step of solidifying a plastic polyurethane resin and then extracting and removing the water-soluble polymer compound and the hydrophilic organic solvent,
When solidifying the thermoplastic polyurethane resin, the polymer dope is housed in a partition member in which at least a part of the hydrophilic organic solvent can be passed and immersed in the coagulation bath. A method for producing a porous material made of thermoplastic polyurethane resin. 2. The polymer dope according to claim 1, wherein the polymer dope comprises 0.2 to 90 parts by weight of a thermoplastic polyurethane resin, 0.2 to 90 parts by weight of the water-soluble polymer compound, and 0.2 to 99 of the oxygen-containing / nitrogen organic solvent. A method for producing a porous material made of a thermoplastic polyurethane resin, comprising 100 parts by weight in total of 6 parts by weight. The polymer dope according to claim 2, wherein the polymer dope is 0.2 to 50 parts by weight of a thermoplastic polyurethane resin, 0.2 to 50 parts by weight of the water-soluble polymer compound,
A method for producing a porous material made of a thermoplastic polyurethane resin, comprising 0.2 to 99.6 parts by weight of the oxygen-containing / nitrogen organic solvent. The thermoplastic resin according to any one of claims 1 to 3, wherein the hydrophilic organic solvent is one or more selected from the group consisting of methanol, ethanol, propanol, acetone, and derivatives thereof. A method for producing a polyurethane resin porous material. 5. The oxygen-containing / nitrogen organic solvent according to claim 1, wherein the oxygen-containing / nitrogen organic solvent is selected from the group consisting of tetrahydrofuran, N-methylpyrrolidone, N, N-dimethylformamide, pyridine, and simple substitutes thereof, or A method for producing a porous material made of a thermoplastic polyurethane resin, characterized by comprising two or more kinds. The thermoplastic polyurethane resin according to any one of claims 1 to 5, wherein the partition member is composed of one or more selected from the group consisting of a metal material, a polymer material, and an inorganic material. A method for producing a porous material. 7. The polymer material according to claim 6, wherein the polymer material is selected from the group consisting of a polyolefin resin, a polyester resin, a polycarbonate resin, a fluorine resin, a silicon resin, a polyamide resin, a polyimide resin, a polyether ether ketone resin, and a polysaccharide. A method for producing a porous material made of a thermoplastic polyurethane resin, characterized in that: The method for manufacturing a porous material made of thermoplastic polyurethane resin according to any one of claims 1 to 7, wherein the partition member is made of a porous material. The method for producing a porous material made of thermoplastic polyurethane resin according to any one of claims 1 to 8, wherein the water-soluble polymer compound is cellulose ether . The porous material made of thermoplastic polyurethane resin according to claim 9, wherein the water-soluble polymer compound is one or more selected from the group consisting of carboxymethylcellulose, methylcellulose, ethylcellulose, and hydroxypropylcellulose. Manufacturing method. A porous material made of a thermoplastic polyurethane resin produced by the method for producing a porous material made of a thermoplastic polyurethane resin according to any one of claims 1 to 10. The porous material made of thermoplastic polyurethane resin according to claim 11, wherein the porous material is substantially homogeneous up to the surface layer.

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