JP4758135B2 - Water-absorbent molded body and method for producing the same - Google Patents

Description

  The present invention relates to a water-absorbent molded body for mounting a sensor that measures body temperature by being attached to the skin, for example, and a method for manufacturing the same.

Conventionally, this type of water-absorbing material has been used as a medical instrument or the like. One such medical instrument is a medical electrode such as an electrode used in a defibrillator. As such a medical electrode, an electrode including a housing, a conductor and an electrolytic solution disposed in the housing, and an adhesive for adhering the surface of the electrode to the skin is known (for example, a patent). Reference 1). The medical electrode includes a water absorbent pad configured to absorb the electrolyte and provide a moist layer between the conductor and the skin. As a water absorbent pad, a sponge or the like is cited. Such a water absorbent pad has a high water absorption enough to prevent the electrolyte from escaping from the electrode and lost, and a low water absorption enough for the electrolyte to contact and moisten the skin . In that case, it has been proposed that a thickener is preferably soaked into the absorbent pad.
JP 2003-235994 A (pages 2 and 8)

  The water absorbing pad described in Patent Document 1 has water absorption adjusted by the water absorbing power of the material itself and the added thickener. However, since the entire water-absorbing pad has a uniform water-absorbing property, a portion with high water absorption for preventing the electrolyte from flowing out and being lost and a small amount of the electrolyte in contact with the skin. It was not possible to distinguish the portion having low water absorption to keep it from seeping out. Therefore, it is difficult to adjust the water absorption, and there is a demand for a material having a high water absorption portion and a low water absorption portion with a single water absorption material.

  Therefore, an object of the present invention is to absorb water on one surface and promote water absorption on the other surface, and have a water absorption suppressing function and a water absorption promoting function, and a method for producing the same. Is to provide.

In order to achieve the above object, the water-absorbent molded article of the invention according to claim 1 includes polyols, polyisocyanates, a blowing agent, and a catalyst, and further includes one hydrophilic group or two groups in one molecule. reacting a feedstock comprising polyethylene glycol or a derivative thereof as a hydrophilic agent consisting of a compound having a hydrophilic group, is obtained by foaming and curing, becomes a polyurethane foam having an open cell structure, of the two opposing surfaces on one surface of the inner, and having a water suppression layer based on the film obtained by heat pressing, have a water absorption layer on the other surface made of foam, which is defined in JIS K6400 at the surface of the water absorbing layer cell The number is 100 to 300 pieces / 25 mm .

According to a second aspect of the present invention, there is provided a method for producing a water-absorbent molded body comprising a step of heat-pressing a polyurethane foam molded body having an open-cell structure and two opposing surfaces, and molding the pressed body , Cutting the intermediate part of the press body, forming a water absorption suppressing layer based on the film obtained by the heat press on the press surface by the heat press, and forming a water absorption layer made of a foam on the cut surface , Polyethylene glycol as a hydrophilicity-imparting agent comprising a polyol, a polyisocyanate, a foaming agent, and a catalyst as the polyurethane foam, and further comprising a compound having one hydrophilic group or two hydrophilic groups in one molecule, or its It is obtained by reacting a raw material containing 0.5 to 10 parts by mass of a derivative per 100 parts by mass of polyols, foaming and curing, JIS K64. The number of cells specified in 00 is 40 to 100 cells / 25 mm, and a polyurethane foam having an air permeability of 10 to 100 cc / cm ² · sec based on JIS L 1096 is used. 10 to 10 times .

According to the present invention, the following effects can be exhibited.
In the water-absorbent molded article according to the first aspect of the present invention, it is made of a polyurethane foam having an open cell structure, and has a water absorption suppressing layer on one surface of a molded article having two opposed surfaces, and the other surface. Has a water absorption layer made of a foam. For this reason, the water-absorbent molded body can suppress water absorption on one side, can promote water absorption on the other side, and can have both a function of suppressing water absorption and a function of promoting water absorption.

  In the method for producing a water-absorbent molded article of the invention according to claim 2, hydrophilicity comprising a polyol, a polyisocyanate, a foaming agent, a catalyst and a compound having one hydrophilic group or two hydrophilic groups in one molecule. A polyurethane foam material containing an imparting agent is reacted, foamed and cured, and a molded product of polyurethane foam having two opposing surfaces is heated and pressed to form a pressed body. Next, by cutting the intermediate portion of the press body, forming a water absorption suppressing layer based on the film obtained by the heat press on the press surface by the heat press, and forming a water absorption layer made of a foam on the cut surface, A water-absorbing molded body can be easily obtained. The obtained water-absorbing molded body has a water absorption suppressing layer on the press surface and a water absorbing layer on the cut surface, and can have both a water absorption suppressing function and a water absorption promoting function.

Embodiments of the present invention are described in detail below.
FIG. 1 (a) is an explanatory view schematically showing a cross section of a plate-like molded body made of polyurethane foam, and FIG. 1 (b) is an explanatory view schematically showing a cross section of the pressed body after hot pressing the molded body. FIG.1 and FIG.1 (c) is explanatory drawing which shows typically the water absorptive molded object obtained by cut | disconnecting a press body along a plate surface in the thickness direction center part. As shown in FIG. 1 (a), a molded body 11 made of polyurethane foam has an open cell structure in which a large number of cells 12 communicate with each other, and can exhibit resilience to a compressive load, that is, soft foam. Is the body. The cells 12 have a long oval shape in the thickness direction of the molded body 11 and exist in a uniform size.

  As shown in FIG. 1B, the press body 13 heat-presses the molded body 11, and has a water absorption suppression layer 15 based on a high-density film on the press surface 14, and between the water absorption suppression layers 15. A water absorbing layer 16 having a low density is formed. The press body 13 is compressed about 5 to 10 times, the press surface 14 side is easily compressed by heating, and becomes a high-density layer coating, and the intermediate portion becomes a low-density layer having a lower density than the coating according to the compression ratio. Yes. Therefore, a high-density coating exhibits a water absorption suppressing function, and a low-density intermediate portion exhibits a water absorption promoting function. The cells 12 of the press body 13 have an oval shape that is long in the plate surface direction, and the cells 12 of the water absorption suppression layer 15 are formed flatter than the cells 12 of the water absorption layer 16.

  As shown in FIG.1 (c), the water absorbing molded object 17 of this embodiment is obtained by cutting the press body 13 in the plate | board surface direction in the thickness direction center part, and heat-presses to the said press surface 14. FIG. And a water absorption suppressing layer 15 made of a film based on the above, and a water absorption layer 16 made of a foam on the cut surface 18. The water absorbent molded body 17 is used as a water absorbent pad, a water absorbent sheet, a water absorbent film, or the like.

  Since the polyurethane foam is hydrophilized with a hydrophilicity imparting agent and heated and pressed as described above, water is easily absorbed into the cells 12 of the polyurethane foam having an open cell structure by capillary action. It is considered a thing. Therefore, the water absorption layer 16 of the polyurethane foam sufficiently absorbs and discharges water, and the water absorption suppression layer 15 restricts the water absorption and discharge because the foam has a high density. And when using this water absorbing molded object 17, the member which should avoid a contact with water is arrange | positioned at the water absorption suppression layer 15 side, and the member which requires water absorption is arrange | positioned at the water absorption layer 16 side.

  For example, in the case of a temperature sensor for measuring body temperature, as shown in FIG. 2, the water absorbent molded body 17 is formed in a donut plate shape, and an adhesive layer 19 is provided on the water absorbent layer 16 side (lower surface side). Yes. Then, a temperature sensor (not shown) is attached to the water absorption suppression layer 15 side, and the adhesive layer 19 on the water absorption layer 16 side is attached to the skin. The central insertion hole 20 is a hole for bringing the sensor element into contact with the skin. By comprising in this way, while being able to avoid a water | moisture content adhering to a temperature sensor, the water | moisture content from skin can be absorbed.

  The polyurethane foam constituting the water-absorbent molded body 17 is obtained by reacting, foaming and curing a polyurethane foam raw material containing polyols, polyisocyanates, a foaming agent and a catalyst. In this case, it is preferable that a hydrophilicity imparting agent is blended in the polyurethane foam raw material in an amount of 0.5 to 10 parts by mass per 100 parts by mass of the polyols. When this compounding quantity is less than 0.5 mass part, sufficient hydrophilicity cannot be provided to a polyurethane foam, and it becomes difficult to obtain water absorption. On the other hand, if it exceeds 10 parts by mass, excessive hydrophilicity is imparted to the polyurethane foam, which is not preferable because the moldability deteriorates.

  As the polyols, polyester polyols or polyether polyols are used. As polyester polyols, in addition to condensation polyester polyols obtained by reacting polycarboxylic acids such as adipic acid and phthalic acid with polyols such as ethylene glycol, diethylene glycol, propylene glycol and glycerin, lactone polyester polyols and polycarbonate systems A polyol is mentioned. Examples of polyether polyols include polypropylene glycol, polytetramethylene glycol, modified products thereof, and compounds obtained by adding alkylene oxide to glycerin. These polyols can change the number of hydroxyl groups and the hydroxyl value by adjusting the kind of raw material components, the molecular weight, the degree of condensation, and the like.

  As the polyols, since the polyester polyol does not exhibit compatibility with polyethylene glycol or its derivative, a unit based on polyethylene glycol or its derivative can appear on the surface in the polyurethane foam, and hydrophilicity can be effectively expressed. preferable.

  The hydroxyl value of the polyols is preferably less than 250 (mgKOH / g), more preferably 50 to 70 (mgKOH / g). By using polyols having such a hydroxyl value, it is possible to obtain a polyurethane foam that is excellent in reactivity with polyisocyanates and is appropriately crosslinked. When the hydroxyl value of polyols is 250 (mgKOH / g) or more, the crosslinking density becomes too high, the foam becomes hard, and the water absorption is also lowered. On the other hand, when the hydroxyl value is less than 50 (mgKOH / g), the hydroxyl value becomes too small, and the crosslinking density of the polyurethane foam tends to be low, and the strength of the foam tends to decrease.

  Next, polyisocyanates to be reacted with polyols are compounds having a plurality of isocyanate groups, specifically, tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate ( NDI), triphenylmethane triisocyanate, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI) and the like are used.

  Here, the isocyanate index (isocyanate index) of the polyisocyanates is preferably 100 to 120. That is, the isocyanate index is a percentage of the equivalent ratio of the isocyanate group of the polyisocyanate to the equivalent of the active hydrogen such as the hydroxyl group of the polyol and the blowing agent (water), but the value exceeds 100. Means that the isocyanate group is in excess of the hydroxyl group. When the isocyanate index is less than 100, the reaction of polyisocyanates with polyols is insufficient, and the foam tends to be soft and the strength tends to decrease. On the other hand, when the isocyanate index exceeds 120, the foam tends to be hard and the water absorption is lowered.

  The foaming agent is for foaming polyurethane into a polyurethane foam. As the foaming agent, water and carbon dioxide gas are used. The blending amount of the foaming agent is preferably 1.0 to 5.0 parts by mass with respect to 100 parts by mass of the polyols in order to reduce the amount of the foaming agent to be less than usual and suppress the progress of the curing reaction. When the blending amount of the foaming agent is less than 1.0 part by mass, the foaming reaction becomes insufficient, and when it exceeds 5.0 parts by mass, the foaming reaction and the crosslinking reaction become excessive, and the foam tends to become hard.

In addition to this foaming agent, an auxiliary foaming agent can also be blended. The auxiliary foaming agent is an organic solvent that is non-reactive with polyols and polyisocyanates, and is used to reduce the hardness of the foam. Examples of the auxiliary foaming agent include methylene chloride (methylene chloride, CH ₂ Cl ₂ ), n-pentane, cyclohexane, and fluorocarbon compounds (trichlorofluoromethane, dichlorodifluoromethane, etc.).

  The catalyst is for accelerating the urethanization reaction between polyols and polyisocyanates. Such catalysts include N, N ', N'-trimethylaminoethylpiperazine, triethylenediamine, dimethylethanolamine, tertiary amines such as N-ethylmorpholine, organometallic compounds such as tin octylate, acetates, alkali metals An alcoholate or the like is used.

Next, the hydrophilicity imparting agent will be described. The hydrophilicity imparting agent is a component for imparting hydrophilicity to the polyurethane foam, and is composed of a compound having one hydrophilic group (monofunctional) or two hydrophilic groups (bifunctional) in one molecule. . When this component reacts with polyisocyanates, it is incompatible with the polyurethane part that becomes the skeleton of the polyurethane foam, especially the polyurethane part obtained from polyester polyol, and is oriented on the surface, and is hydrophilic to the polyurethane foam. It is thought that it gives. Examples of the hydrophilic group include a hydroxyl group (—OH), a polyoxyethylene group [— (CH ₂ CH ₂ O) —] and the like. As the monofunctional hydrophilicity imparting agent, polyoxyethylene alkyl ether or the like is used. As the bifunctional hydrophilicity imparting agent, 1,6-hexanediol, 1,10-decanediol, acetylene glycol, polyethylene glycol (polyethylene oxide), an ethylene oxide adduct of acetylene glycol, or the like is used. These hydrophilicity-imparting agents can be used alone or in combination of two or more.

  Of these hydrophilicity-imparting agents, polyethylene glycol or its derivatives are preferred. As the derivative of polyethylene glycol, polyoxyethylene alkyl ether (the alkyl group has 11 to 50 carbon atoms, usually 12 to 18, and the number of added moles of ethylene oxide 3 to 40) is used. Further, the molecular weight of polyethylene glycol or its derivative is preferably about 200 to 600.

In addition, as a raw material of the polyurethane foam, a foam stabilizer such as a surfactant, a flame retardant such as a condensed phosphate ester, an antioxidant, a plasticizer, an ultraviolet absorber, a colorant and the like can be used.
A polyurethane foam is produced by reacting the polyurethane foam raw material to foam and cure, but the reaction at that time is complicated, and basically the following reaction is the main component. . That is, addition polymerization reaction (polyurethanation reaction) between polyols and polyisocyanates, foaming (foaming) reaction between polyisocyanates and water as a blowing agent, and crosslinking between these reaction products and polyisocyanates ( Curing) reaction. Here, the above polyols react with polyisocyanates to form a basic skeleton of polyurethane, and polyethylene glycol or a derivative thereof as a hydrophilicity imparting agent has a hydroxyl group and reacts with polyisocyanates. The basic skeleton of polyurethane is a component that exhibits incompatibility, is oriented on the surface, and exhibits hydrophilicity.

  When producing a polyurethane foam, a one-shot method or a prepolymer method is employed. The one-shot method is a method in which polyols and polyisocyanates are directly reacted. The prepolymer method is a method in which a part of a polyol and a polyisocyanate are reacted in advance to obtain a prepolymer having an isocyanate group or a hydroxyl group at a terminal, and the polyol or the polyisocyanate is reacted therewith. The one-shot method is a preferable method because the manufacturing process is one step compared to the prepolymer method, and there are few restrictions on the manufacturing conditions, and the manufacturing cost can be reduced.

  As a polyurethane foam, a slab polyurethane foam is preferable. The slab polyurethane foam discharges the reaction raw material (reaction mixture) mixed and stirred by the one-shot method onto a belt conveyor, and while the belt conveyor moves, the reaction raw material naturally foams at room temperature and atmospheric pressure. Obtained by curing. Thereafter, it is cured (cured) in a drying furnace, cut into a predetermined shape, and formed into a molded body 11, which is subjected to hot pressing. In addition, the polyurethane foam molded body 11 can be obtained by a molding method, an on-site spray molding method, or the like.

  Depending on the raw material composition, reaction conditions, and the like of the polyurethane foam as described above, the resulting polyurethane foam is a soft foam having an open-cell structure with the cell membrane broken and the cells connected. As this polyurethane foam, the number of cells specified in JIS K6400 is preferably 40 to 100 cells / 25 mm. When the number of cells is less than 40/25 mm, capillary action is unlikely to occur when the polyurethane foam is heated and pressed, resulting in a decrease in water absorption. On the other hand, when the number of cells exceeds 100 cells / 25 mm, physical properties such as strength of the polyurethane foam deteriorate. Further, the number of cells on the cut surface 18 of the press body 13 at the time of 5 times compression is preferably 100 to 250/25 mm, and the number of cells on the cut surface 18 of the press body 13 at the time of 10 times compression is 150 to 300. / 25 mm is preferable.

The air permeability based on JIS L 1096 is preferably 10 to 100 cc / cm ² · sec. When the air permeability is less than 10 cc / cm ² · sec, the connectivity of the cell 12 is lowered and the water absorption tends to be deteriorated. On the other hand, when the air permeability exceeds 100 cc / cm ² · sec, the connectivity of the cells 12 becomes too large, and the strength of the foam is lowered. Further, the density based on JIS K 7222; 1999 is preferably ³⁰ to 80 kg / m ³ . When this density is less than 30 kg / m ³ , the degree of foaming is large, and physical properties such as strength of the foam deteriorate. When the density exceeds 80 kg / m ³ , the connectivity of the cells 12 tends to be lowered, and water absorption may be deteriorated.

  The polyurethane foam molded body 11 is heated and pressed to form a pressed body 13, which is heated at a temperature of 180 to 220 ° C. for about 3 to 10 minutes. If the temperature of the hot press is less than 180 ° C., the compression effect is weak, and if it exceeds 220 ° C., physical properties such as the strength of the polyurethane foam deteriorate, which is not preferable. Heat pressing is performed under such conditions, and the polyurethane foam molded body 11 is usually compressed 5 to 10 times to form the pressed body 13. The water-absorbing molded body 17 is obtained by cutting an intermediate portion of the press body 13 in the plate surface direction.

  Now, the operation of the present embodiment will be described. When a polyurethane foam is produced, a monofunctional or bifunctional hydrophilicity imparting agent such as polyethylene glycol is blended with the raw material of the polyurethane foam. By orienting the hydrophilicity imparting agent on the surface, a polyurethane foam molded body 11 with improved hydrophilicity is obtained. This molded body 11 is compressed by hot press molding. The compressed press body 13 is formed with a water absorption suppression layer 15 formed of a high-density film formed by crushing the skeleton (cell film) of the cell 12 on both surfaces thereof, and a low-density layer is formed in the middle part thereof. A water absorption layer 16 made of a foam is formed.

  The press body 13 is cut into two minutes to obtain a water absorbent molded body 17. When the water absorbent molded body 17 is used as a water absorbent pad, it is formed in a donut plate shape as shown in FIG. 2, and the press surface 14 is provided with a water absorption suppression layer 15 made of a film, and a cut surface 18. Is provided with a water absorption layer 16 made of foam. An adhesive layer 19 is provided on the lower surface of the water absorption layer 16 and is adhered to the skin. A temperature sensor is supported on the water absorption suppression layer 15. Then, while sweat from the skin is absorbed into the water absorption layer 16, the water absorption suppression layer 15 blocks water and prevents the temperature sensor from being exposed to moisture. This is because the polyurethane foam has an open-cell structure and the hydrophilicity of the foam is increased by a hydrophilicity-imparting agent such as polyethylene glycol, and water is easily absorbed into the cell 12 by capillary action, and at the same time, This is because the passage of water is blocked by the formed high-density film.

The effects exhibited by the above embodiment will be described collectively below.
In the water-absorbent molded body 17 of the present embodiment, the water-absorbing suppression layer 15 made of a film based on a hot press of the foam is provided on one surface of the molded body 11 made of a polyurethane foam having an open cell structure, and the other Has a water absorption layer 16 made of a foam. For this reason, the water-absorbent molded body 17 can suppress water absorption on one surface, can promote water absorption on the other surface, and can have both a function of suppressing water absorption and a function of promoting water absorption.

  This water-absorbing molded body 17 heat-presses a polyurethane foam obtained by reacting, foaming and curing a polyurethane foam material containing polyols, polyisocyanates, foaming agent, catalyst and hydrophilicity-imparting agent. Therefore, it is easily manufactured. By the heat press, the water absorption suppressing function is expressed on the press surface 14 based on the film formed by compression of the foam. On the other hand, when the hydrophilic group of the hydrophilicity imparting agent contained in the raw material of the polyurethane foam is oriented on the surface of the foam, hydrophilicity is imparted to the polyurethane foam, and water is sufficiently absorbed by the cells 12 of the polyurethane foam. Is done. Therefore, the obtained water-absorbing molded body 17 has a water absorption suppressing layer 15 made of a film on the press surface 14 and also has a water absorbing layer 16 made of a foam on the cut surface 18, and functions to suppress water absorption and promote water absorption. It is possible to combine these functions.

-The said effect can fully be exhibited because the said hydrophilicity imparting agent is polyethyleneglycol or its derivative (s).
-In the said polyurethane foam, the water absorption of the water absorbing molded object 17 can be improved based on sufficient cell number by setting the cell number prescribed | regulated to JISK6400 to 40-100 cell / 25mm.

  In addition, by setting the blending amount of the hydrophilicity imparting agent to 0.5 to 10 parts by mass per 100 parts by mass of polyols, it is possible to sufficiently impart hydrophilicity to the polyurethane foam, and the water absorption of the water absorbent molded body 17 Can be fully exhibited.

  Furthermore, the effect of suppressing water absorption on the press surface 14 of the water-absorbent molded body 17 can be improved by setting the compression ratio by the heating press to 5 to 10 times.

Hereinafter, the embodiment will be described more specifically with reference to examples and comparative examples.
(Examples 1-5 and Comparative Example 1)
Open cells by reacting polyester polyol as polyols and tolylene diisocyanate as polyisocyanates, N-ethylmorpholine as amine catalyst, water in the presence of water as a blowing agent, and foaming and curing as shown in Table 1. A molded product 11 of polyurethane foam having a structure was produced. The compounding amounts shown in Table 1 are all parts by mass. The obtained molded body 11 of polyurethane foam was compressed 5 times and 10 times under the conditions of 200 ° C. and 5 minutes by a hot press apparatus, whereby a pressed body 13 was obtained. The meanings of the abbreviations in Table 1 are shown below.

N2200: Polyester polyol, hydroxyl value 60 mgKOH / g, manufactured by Nippon Polyurethane Industry Co., Ltd. NEM: N-ethylmorpholine (amine catalyst)
SE232: Silicone surfactant, manufactured by Nippon Unicar Co., Ltd. PEG200: Polyethylene glycol, molecular weight 200, hydroxyl value 561 mgKOH / g, functional group (hydroxyl group) number 2, Sanyo Chemical Industries, Ltd. LS106P: polyoxyethylene alkyl ether, Molecular weight 515, hydroxyl value 106 mgKOH / g, functional group (hydroxyl group) number 1, manufactured by Kao Corporation T-80: Tolylene diisocyanate (80% by mass of 2,4-tolylene diisocyanate and 20 mass by mass of 2,6-tolylene diisocyanate) %), Manufactured by Nippon Polyurethane Industry Co., Ltd. The obtained polyurethane foam molded body 11 or press body 13 was measured for density, cell number and water absorption by the methods shown below, and the results are shown in Table 1. It was described together.

Density (kg / m ³ ): Measured according to JIS K 7222; 1999.
Number of cells (cells / 25 mm): All were measured in accordance with JIS K6400. The 5 times and 10 times compression of the number of cells is the number of cells on the cut surface after each compression.

Air permeability (cc / cm ² · sec): Measured according to JIS L 1096.
Water Absorption: After applying 0.05 ml of water droplets to the surface of the polyurethane foam molded body 11 or press body 13, the time (seconds) required to completely absorb from the surface to the inside was measured. This water absorption was performed on the surface of the foam (water absorption suppressing layer 15) and the central cut surface (water absorption layer 16).

表１に示した結果から、実施例１のポリウレタン発泡体においては、親水性付与剤としてポリエチレングリコールを用いて製造され、得られた成形体１１の加熱プレス加工によりそのプレス面１４に吸水抑制層１５が形成されている（５倍圧縮及び１０倍圧縮）。このため、カット面１８では連続気泡構造を形成するセル１２内への吸水性が向上し、しかもプレス面１４とカット面１８との間に吸水性の差を設けることができた。実施例２においても、親水性付与剤としてポリオキシエチレンアルキルエーテルを用いることにより、実施例１と同様の結果を得ることができた。

From the results shown in Table 1, the polyurethane foam of Example 1 was produced using polyethylene glycol as a hydrophilicity-imparting agent, and a water absorption suppressing layer was formed on the press surface 14 of the resulting molded body 11 by hot pressing. 15 is formed (5 times compression and 10 times compression). For this reason, the water absorption into the cell 12 forming the open cell structure was improved on the cut surface 18, and a water absorption difference could be provided between the press surface 14 and the cut surface 18. In Example 2, the same results as in Example 1 could be obtained by using polyoxyethylene alkyl ether as the hydrophilicity-imparting agent.

  In Example 3, since the blending amount of polyethylene glycol was increased, the hydrophilicity of the foam was improved, and the water absorption on the surface side of the foam was slightly higher than that of Example 1. Also in Example 4, since the blending amount of polyoxyethylene alkyl ether was increased, the hydrophilicity of the foam was improved, and the water absorption on the surface side of the foam was slightly higher than that of Example 2. In Example 5, as a result of decreasing the blending amount of water as a foaming agent and increasing the density of the foam, a result comparable to Example 2 was obtained.

On the other hand, in Comparative Example 1, since the polyurethane foam did not have hydrophilicity, the expression of water absorption was not observed even when compressed 5 times and 10 times.
In addition, this embodiment can also be changed and embodied as follows.

  ・ When reacting, foaming, and curing the polyurethane foam raw material, the periphery of the foam is cooled to suppress foaming, and the outer periphery of the foam is configured to have a high density and the inside has a low density. It is also possible. And the molded object 11 can be obtained from the polyurethane foam, and the water-absorbing molded object 17 which has the water absorption suppression layer 15 in the one surface from the molded object 11, and has the water absorption layer 16 in the other surface can also be obtained.

  -As a derivative of polyethylene glycol, polyoxyethylene alkylphenyl ether such as polyethylene glycol monononylphenyl ether can be used.

A surfactant having a hydrophilic / lipophilic ratio (HLB) of 8 to 18 may be blended as a raw material for the polyurethane foam to increase the hydrophilicity of the polyurethane foam.
Further, the technical idea that can be grasped from the embodiment will be described below.

And manufacturing method of the water absorbent molded body you wherein polyols are polyester polyols. According to this manufacturing method, it is possible to further improve the hydrophilicity of Polyurethane foam.

(A) is explanatory drawing which fractures | ruptures the molded object of the polyurethane foam in embodiment, and shows typically, (b) is explanatory drawing which fractures | ruptures the press body obtained by heat-pressing, and shows typically (c) ) Is an explanatory view schematically showing a cut water-absorbent molded body obtained by cutting in the plate surface direction at the center in the thickness direction of the pressed body. The perspective view which shows a water absorbing pad.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Molded body, 13 ... Press body, 14 ... Press surface, 15 ... Water absorption suppression layer, 16 ... Water absorption layer, 17 ... Water absorption molded body, 18 ... Cut surface.

Claims (2)

Reacts a raw material containing polyethylene glycol or a derivative thereof as a hydrophilicity imparting agent comprising a polyol, a polyisocyanate, a foaming agent, and a catalyst, and further comprising a compound having one hydrophilic group or two hydrophilic groups in one molecule. Made of polyurethane foam having an open cell structure , obtained by foaming and curing ,
On one surface of the two opposing surfaces, and having a water suppression layer based on the film obtained by heat pressing, have a water absorption layer of foam on the other side,
The water- absorbent molded article, wherein the number of cells defined in JIS K6400 on the surface of the water-absorbing layer is 100 to 300/25 mm . A step of heat-pressing a polyurethane foam molded body having an open-cell structure and having two opposing surfaces to form a pressed body ;
Cutting the intermediate portion of the pressing member, thereby forming a water suppression layer based on film obtained by heat-press to press surface by the heating press, and a step of forming a water absorbing layer made of foam cut surface ,
Polyethylene glycol as a hydrophilicity-imparting agent comprising a polyol, a polyisocyanate, a foaming agent, and a catalyst as the polyurethane foam, and further comprising a compound having one hydrophilic group or two hydrophilic groups in one molecule, or its A raw material containing 0.5 to 10 parts by mass of a derivative per 100 parts by mass of polyol is reacted, foamed and cured, and the number of cells specified in JIS K6400 is 40 to 100/25 mm. Using a polyurethane foam having an air permeability based on 1096 of 10 to 100 cc / cm ² · sec,
The method for producing a water-absorbent molded article, wherein the compression ratio by the heating press is 5 to 10 times .

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