JP2016194065A - Hydrophilic ultrahigh molecular weight plastic porous sheet and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly water-absorptive hydrophilic porous sheet, a hydrophilic porous sheet also having excellent adhesiveness, and a simple manufacturing method of the porous sheet.SOLUTION: A hydrophilic ultrahigh molecular weight plastic porous sheet is configured to: have an absorption rate of 15 mm/3 min. or more when part of the sheet is immersed in pure water under an atmosphere of 25°C and 60%RH; include an ultrahigh molecular weight plastic material; and exhibit no specific absorption at 3000 to 3500 cmin IR spectrum measured by infrared spectroscopy (FT-IR).SELECTED DRAWING: None

Description

  The present invention relates to an ultrahigh molecular weight plastic porous sheet that is required to have hydrophilicity, air permeability, and absorbability of pure water, and a method for producing the same.

  Porous sheets of polyolefin resin particles are widely used in various filters and buffer materials for adsorption and fixation because of their excellent filtration function and permeability. Among these, especially the hydrophilic polyethylene porous sheet is used for water absorption, retention, diffusion, permeation, etc. due to its hydrophilicity and water absorption, and a polyolefin sintered body described in Patent Document 1 has been developed. ing.

  As a porous sheet having such a water absorbing function, a hydrophilic synthetic fiber sheet or nonwoven fabric, or a natural fiber cloth, and a hydrophilic porous thermoplastic resin microporous film or a water absorbing polymer, Metal or ceramic sintered bodies have also been developed.

  Such a hydrophilic polyethylene porous sheet has excellent dimensional stability, high mechanical strength, and moldability that can cope with complex shapes when it is absorbed by water. Applications are expected in many fields such as body.

  In order to impart hydrophilicity to the polyethylene porous sheet, a method in which a substance having a hydrophilic functional group is introduced into the raw polyethylene powder by graft polymerization or the like as in the method described in Patent Document 2 is common. However, there are problems in that the manufacturing process is complicated and necessary and sufficient hydrophilicity or water absorption is difficult to obtain.

Japanese Patent Publication No. 4-28021 JP 2009-114238 A

  An object of the present invention is to provide a hydrophilic porous sheet having high water absorption without introducing a substance having a hydrophilic functional group. Furthermore, an object of this invention is to provide the hydrophilic porous sheet which is excellent also in adhesive force. Another object of the present invention is to provide a simple method for producing the porous sheet.

The hydrophilic ultra high molecular weight plastic porous sheet of the present invention has an absorption rate of 15 mm / 3 min or more when one end of the sheet is immersed in pure water in an atmosphere of 25 ° C. and 60% RH, and has an ultra high molecular weight. In the IR spectrum composed of plastic and measured by infrared spectroscopy (FT-IR), no characteristic absorption is observed at 3000 to 3500 cm ⁻¹ .

  The method for producing a hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention includes a step of performing antistatic treatment and / or plasma treatment on a porous sheet, and the porous sheet is made of ultrahigh molecular weight plastic. The plasma treatment in the case of being configured and having an average pore diameter of less than 20.0 μm and not carrying out antistatic treatment is carried out in an oxygen gas atmosphere.

  ADVANTAGE OF THE INVENTION According to this invention, it is not necessary to introduce | transduce (for example, laminate | stack) the substance which has a hydrophilic functional group, and can provide the hydrophilic ultra high molecular weight plastic porous sheet which shows high water absorption. Furthermore, this invention can provide the hydrophilic porous sheet which is excellent also in adhesive force. Further, by using the production method of the present invention, a porous sheet having improved pure water absorbability can be obtained easily.

The hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention has an absorption rate of 15 mm or more per 3 minutes when one end of the sheet is immersed in pure water in an atmosphere of 25 ° C. and 60% RH. It is made of plastic and is characterized in that no characteristic absorption is observed at 3000 to 3500 cm ⁻¹ in an IR spectrum measured by infrared spectroscopy (FT-IR).

  The method for measuring the absorption rate is as described in Examples described later. The hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention can be used as a water-absorbing sheet, and the absorption speed when one end of the sheet is immersed in pure water in an atmosphere of 25 ° C. and humidity 60% RH is 20 mm / 3. Min. Or more, preferably 25 mm / 3 min. Or more, more preferably 30 mm / 3 min. Or more, particularly preferably 35 mm / 3 min. Or more, further particularly preferably 40 mm / 3 min. Or more, particularly preferably 45 mm / 3 min. Or more. 55 mm / 3 min or more is most preferable.

  The adhesive strength of the hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention is preferably 0.5 N / mm or more, more preferably 2.1 N / mm or more, and further preferably 2.5 N / mm or more. The method for measuring the adhesive force is as described in Examples described later.

  The hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention preferably has an absorption rate of 15 mm / 3 min or more and an adhesive strength of 2.1 N / mm or more, and an absorption rate of 20 mm / 3 min. More preferably, the adhesive strength is 2.1 N / mm or more, more preferably the absorption rate is 25 mm / 3 minutes or more and the adhesive strength is 2.5 N / mm or more.

  The ultra high molecular weight plastic constituting the hydrophilic ultra high molecular weight plastic porous sheet of the present invention is not particularly limited, and examples thereof include ultra high molecular weight polyethylene, ultra high molecular weight polypropylene, ultra high molecular weight polyvinyl chloride, and ultra high molecular weight polyamide. Ultra high molecular weight polyethylene (hereinafter also referred to as UHMWPE) is preferable. These may be used individually by 1 type, and 2 or more types may be mixed and used for them. Moreover, these can use a commercial item. Examples of commercially available high molecular weight plastics include ultra high molecular weight polyethylene such as Hi-Zex Million (Mitsui Chemicals), Sunfine UH, UTS (Asahi Kasei Chemicals), HIFAX 1000 (Hercules), and Hostalen GUR (Hoechst); Examples include ultra high molecular weight polyvinyl chloride such as TK2500 series (Shin-Etsu Chemical); ultra high molecular weight polyamide such as Daiamide (Daicel Chemical Industries).

  In the present invention, the weight average molecular weight (Mw) (hereinafter, also simply referred to as average molecular weight) of the ultra high molecular weight plastic is not particularly limited, but is preferably 500,000 or more, more preferably 1,000,000 or more, and further preferably 1,500,000 or more. 2 million or more is particularly preferable. The upper limit of the weight average molecular weight (Mw) is not particularly limited, but is preferably 15 million or less, more preferably 12 million or less, further preferably 9 million or less, and particularly preferably 8 million or less. The weight average molecular weight is a value measured by a light scattering measurement method.

  The ultra high molecular weight plastic porous sheet used as the material can be produced by a known method, for example, according to the method described in JP-B-7-55541 and JP-A-2002-177390. . For example, the ultra high molecular weight plastic powder is filled into a shape holder (such as a mold), and the plastic formed on the mold is sintered in a steam atmosphere heated to a temperature higher than the melting point of the plastic and then cooled. Can be produced. Specifically, when the ultra high molecular weight plastic is ultra high molecular weight polyethylene, a predetermined dispersion containing ultra high molecular weight polyethylene powder or the like is prepared, and the dispersion is applied in a sheet form. An ultra-high molecular weight plastic porous sheet can be produced by allowing it to cool to room temperature after performing a certain amount of heat treatment.

  Moreover, the ultra high molecular weight plastic porous sheet used as a material may be manufactured using additives such as a dispersant and a thickener.

  Examples of the dispersant include a surfactant, and a nonionic surfactant is preferable. Nonionic surfactants include glycerin fatty acid ester and its alkylene glycol adduct, polyglycerin fatty acid ester and its alkylene glycol adduct, propylene glycol fatty acid ester and its alkylene glycol adduct, sorbitan fatty acid ester and its alkylene glycol adduct, Fatty acid ester of sorbitol and its alkylene glycol adduct, polyoxyethylene glycerin fatty acid ester, polyalkylene glycol fatty acid ester, sucrose fatty acid ester, glycerin alkyl ether, polyoxyalkylene alkyl ether, poly (oxyethylene) alkylphenyl ether, poly ( Oxyethylene) alkyl ether, polyoxyethylene hydrogenated castor oil, lanolin alkylene glycol Adducts, polyoxyethylene - polyoxypropylene block copolymers, and the like. As for carbon number of the fatty acid in the illustration of an above-mentioned nonionic surfactant, 12-18 are preferable. The HLB value of the nonionic surfactant is not particularly limited, but may be 12.5 or more. Further, the HLB value of the nonionic surfactant may be less than 15.0 or less than 14.5. These can use a commercial item. As a commercial item, for example, Triton X-100 (Triton X-100; HLB value 13.5, a kind of polyoxyethylene alkylphenyl ether, polyethylene glycol p- (1,1,3,3-tetramethylbutyl) -Including compounds such as phenyl ether; manufactured by Roche Applied Science). The amount of the dispersant used is not particularly limited, but is preferably ultra-high molecular weight plastic powder: dispersant (volume ratio) = 1: 0.01 to 1: 0.20, and 1: 0.05 to 1: 0. 15 is more preferable.

  The thickener is not particularly limited, but natural and synthetic clay minerals (including organically modified viscosity minerals) such as bentonite, montmorillonite, zauconite, nontronite, saponite, hectorite, vermiculite, synthetic hectorite; Plant thickeners such as gum, tragacanth and carrageenan; microbial thickeners such as xanthan gum; animal thickeners such as gelatin and sodium chondroitin sulfate; methylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, nitrocellulose, ethylcellulose, hydroxy Cellulose derivatives such as ethyl cellulose and hydroxypropycellulose; starch-based thickeners such as rice starch and wheat starch; Algins such as sodium alginate and propylene glycol alginate System thickener; polyvinyl alcohol, polyvinyl pyrrolidone, vinyl derivatives of polyvinyl acetate and the like; sodium polyacrylate, polyacrylic resin alkanolamine solution, polyethyl methacrylate, such as acrylic derivatives, such as carboxyvinyl polymers. The amount of thickener used is not particularly limited, but it is preferably ultrahigh molecular weight plastic powder: thickener (volume ratio) = 1: 0.005 to 1: 0.10, and 1: 0.01 to 1: 0.08 is more preferable. Moreover, the usage-amount of a thickener is although it does not specifically limit, Dispersant: Thickener (volume ratio) = 1: 0.05-1: 0.9 are preferable, and 1: 0.1-1: 0. 8 is more preferable.

  The hydrophilic ultra high molecular weight plastic porous sheet of the present invention may contain other resins as long as the ultra high molecular weight plastic is mainly constituted as long as the effects of the present invention are not hindered. Examples of such other resins include high-density polyethylene and low-density polyethylene. The blending amount of such other resins is not particularly limited as long as the effect of the present invention is not hindered, but is preferably 10% by mass or less with respect to the entire hydrophilic ultrahigh molecular weight plastic porous sheet. 0.0 mass% or less is more preferable, and 1.0 mass% or less is more preferable.

  As described above, the hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention may contain other resins as long as the effects of the present invention are not hindered, but the resin material (plastic) is an ultrahigh molecular weight. What consists only of plastic is preferable.

  The average pore size of the hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention is less than 20.0 μm, preferably 3.0 to 18.0 μm, in view of obtaining higher water absorption after the plasma treatment. Preferably it is 5.0-15.0 micrometers, More preferably, it is 8.0-13.0 micrometers. Further, the average pore diameter of the porous sheet may be 1.0 μm or more, or 2.0 μm or more.

  The average pore size in the present invention was determined by measuring the pore size distribution by the BJH method using a specific surface area / pore distribution measuring device ASAP2010 (manufactured by Shimadzu Corporation) by nitrogen adsorption / desorption method. Value.

  The porosity of the hydrophilic ultra-high molecular weight plastic porous sheet of the present invention is more than 30% from the viewpoint that higher water absorption can be obtained after the plasma treatment when only the plasma treatment is performed without the antistatic treatment. % Or less is preferable, 33 to 70% is more preferable, and 35 to 60% is more preferable. When the antistatic treatment is performed before or after the plasma treatment, the porosity of the porous sheet is preferably more than 20% and not more than 70% from the viewpoint of obtaining higher water absorption after both treatments. 65% is more preferable, and 25 to 50% is more preferable.

The porosity in this invention means the volume ratio of the part of the hole in a porous sheet, and is a value defined by a following formula.
Porosity = {volume of pore portion / (volume of porous material portion + volume of pore portion)} × 100 (%)
The porosity in the present invention is due to open pores and does not include closed pores.

  By using such a porous sheet as a material, the water absorption of the sheet after the plasma surface treatment can be further increased.

  The thickness of the hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention is not particularly limited, but is preferably about 5 to 500 μm, more preferably about 10 to 450 μm, further preferably about 50 to 400 μm, and about 80 to 350 μm. Particularly preferred.

  The hydrophilic ultra high molecular weight plastic porous sheet of the present invention has a step of performing antistatic treatment and / or plasma treatment on the porous sheet of the material, and the porous sheet comprises the above ultra high molecular weight plastic. The plasma treatment when the average pore diameter is less than 20.0 μm and the antistatic treatment is not performed is performed in an oxygen gas atmosphere, and the antistatic treatment is performed before or after the plasma treatment. Is carried out in an oxygen gas or argon gas atmosphere and can be produced by a production method.

  In the manufacturing method of the present invention described above, the treatment to be performed on the porous sheet of material is performed only when the plasma treatment is performed without performing the antistatic treatment; or the plasma treatment is preferably performed before or after the antistatic treatment. .

  In the plasma treatment step when the antistatic treatment is not performed, the use of oxygen gas makes it possible to obtain superior water absorption compared to non-reactive gases such as argon and helium.

  In the plasma treatment step when the plasma treatment is performed before or after the antistatic treatment, excellent water absorption can be obtained by using oxygen gas or argon gas.

  The amount of oxygen gas introduced in the plasma treatment step when the antistatic treatment is not performed is not particularly limited as long as the effect of the present invention is obtained, but is preferably 10 to 100 sccm from the viewpoint of obtaining higher water absorption after the plasma treatment. 20-80 sccm is more preferable, and 30-50 sccm is further more preferable.

  The amount of oxygen gas or argon gas introduced in the plasma treatment step when performing the plasma treatment before or after the antistatic treatment is not particularly limited as long as the effect of the present invention can be obtained. -600 sccm is preferable, 110-550 sccm is more preferable, 150-500 sccm is further more preferable, and 200-480 sccm is especially preferable.

  The gas pressure in the plasma treatment step is not particularly limited, but higher water absorption can be obtained after performing the plasma treatment without the antistatic treatment and after performing the plasma treatment before or after the antistatic treatment. Therefore, 0.5 to 10 Pa is preferable, and 2.0 to 7.0 Pa is more preferable.

The product of the process density and processing time in the plasma treatment step of the case without antistatic treatment (processing energy), from the viewpoint of high water absorption by after the plasma treatment is obtained, 10J / cm ² or more 300 J / cm ² or less is preferable , 15 J / cm ² or more 300 J / cm ² and more preferably less, more preferably 20 J / cm ² or more 250 J / cm ² or less, 25 J / cm ² or more 200 J / cm ² or less is particularly preferred. The product of the processing density (processing power [W] / processing area [cm ² ]) and processing time ([sec]) can be adjusted using a high frequency power source of 5 to 15 MHz.

The product (processing energy) of the processing density and the processing time in the plasma processing step when performing the plasma processing before or after the antistatic treatment is 0.10 J / cm ² or more and 10 J / cm from the point that higher water absorption is obtained. is preferably less than ^2, more preferably 0.20 J / cm ² or more 8.0J / cm ² or less, more preferably 0.30J / cm ² or more 5.0J / cm ² or less, 0.35J / cm ² or more 4. 0 J / cm ² or less is particularly preferable.

  Examples of the antistatic treatment include a method of coating the porous sheet with an antistatic agent. The antistatic agent is not particularly limited, and examples thereof include a cationic surfactant, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, and the like. A cationic surfactant, an anionic surfactant, Nonionic surfactants are preferred. These antistatic agents may be used singly or in combination of two or more, but it is preferable not to use a cationic surfactant and an anionic surfactant together. It does not specifically limit as an antistatic agent of this invention, You may further contain additives, such as a ultraviolet absorber and a mold release agent.

  The cationic surfactant used as the antistatic agent is not particularly limited, and alkyl ammonium acetates, alkyl dimethyl benzyl ammonium salts, alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, alkyl pyridinium salts, oxyalkylene alkyl amines, And oxyalkylene alkylamines.

  The anionic surfactant used as the antistatic agent is not particularly limited, but includes fatty acid soda soaps such as sodium stearate soap, alkyl sulfates such as sodium lauryl sulfate, alphasulfo fatty acid ester salts, alkyl ether sulfates, alkylbenzene. Examples thereof include sodium sulfonates, sodium alkylnaphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphates, alkyl diphenyl ether disulfonates and the like.

  Examples of the zwitterionic surfactant used as the antistatic agent include alkylcarboxybetaines.

  Examples of the nonionic surfactant used as the antistatic agent are the same as those described above.

  A commercially available product can be used as the antistatic agent. Examples of commercially available products include polyoxyethylene-polyoxypropylene block copolymer type nonionic surfactants such as Adeka (registered trademark) Pluronic L · P · F series and Adeka (registered trademark) Pluronic TR series; Adekatol LB series, Alkyl ether type nonionic surfactants such as Adecatol LA series and Adekatol TN series; Ester type nonionic surfactants such as Adecanol NK (glyceride ethylene oxide adduct); Special phenol type nonionic surfactants such as Adekatol PC; Sulfate-type anionic surfactants such as Adeka Hope series; Phosphate-type or succinate-type anionic surfactants such as Adekacol series; Quaternary cationic surfactants such as Adekamin series ( As mentioned above, cationic surfactants such as Eleknon series (manufactured by Dainichi Seika Kogyo Co., Ltd.), amphoteric surfactants such as electro stripper AC (made by Kao Corporation), and the like can be mentioned.

  The coating method is not particularly limited, and a known method can be adopted. Coating methods include, for example, casting method, dipping method, roll coating method, gravure coating method, screen printing method, reverse coating method, spray coating method, kiss coating method, die coating method, metal ring bar coating method, coating method using a chamber doctor. , Curtain coating method, bar coating method and the like.

  You may perform a drying process, after coating an antistatic agent with respect to a porous sheet. Although the temperature of a drying process is not specifically limited, For example, about 50-130 degreeC may be sufficient, and about 60-110 degreeC may be sufficient.

  In the method for producing a porous sheet of the present invention, other treatments other than the above-described plasma treatment and antistatic treatment such as corona discharge treatment may be performed in order to further impart hydrophilicity, but it is not particularly necessary.

The hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention hardly shows characteristic absorption at 3000 to 3500 cm ⁻¹ in the IR spectrum measured by infrared spectroscopy (FT-IR). This is because the hydrophilic functional group (OH group) is not introduced to the surface of the hydrophilic porous sheet (up to several tens of μm in the thickness direction from the surface) to the extent that it can be detected by infrared spectroscopy (FT-IR). That is, it means that the introduction amount of the hydrophilic functional group is extremely small.

  The present invention includes embodiments in which the above-described configurations are variously combined within the technical scope of the present invention as long as the effects of the present invention are exhibited.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited at all by these Examples.

[Example 1]
UHMWPE powder (weight average molecular weight 4.5 million) was mixed with water, a dispersant (trade name: Triton X-100 (Roche Applied Science)), and a thickener (carboxymethylcellulose sodium) to obtain a dispersion. The compounding ratio at this time was water / UHMWPE powder / dispersant / thickener = 100/60/5/2 (volume ratio). This dispersion was applied to a polyimide film (JIS B 0601: 2013 arithmetic average roughness Ra <0.1) with an arbitrary thickness using a doctor blade. The dispersion applied on this film was put into a drier set at 180 ° C. and allowed to stand for 10 minutes. After drying, the polyimide film laminate was taken out and naturally cooled to room temperature, and then the polyimide film on the back surface was peeled off from the laminate. Thereafter, the obtained sheet was washed with distilled water in an ultrasonic cleaning tank, and the dispersant was sufficiently extracted from the sheet to obtain a UHMWPE porous sheet having an average pore diameter of 10 μm and a porosity of 40%.

The obtained UHMWPE porous sheet was subjected to plasma treatment. As the plasma treatment, sputter etching treatment using high frequency plasma in the presence of O ₂ gas was performed. The sputter etching process was performed using a high frequency power source with an O ₂ gas introduction amount of 30 sccm in the vacuum chamber and a gas pressure in the chamber of 3.6 Pa. At this time, the product of the treatment density and the treatment time was 30 J / cm ² , whereby a hydrophilic UHMWPE porous sheet was obtained.

(Measurement of FT-IR)
Each sheet of the obtained examples and comparative examples was measured with FT-IR manufactured by JASCO Corporation. The results are shown in Table 1.

(Water absorption evaluation)
With respect to each of the obtained sheets of Examples and Comparative Examples, one end of the sheet was purified with pure water in an atmosphere of 25 ° C. and 60% RH in accordance with the Bayrec method of JIS L 1907: 2010 (Fabricity water absorption test method). The sample was soaked in 1 cm and then pulled up after being left for 3 minutes, and the distance that water moved in the sheet was measured and evaluated. The results are shown in Table 1.

(Adhesion evaluation)
Each sheet of the obtained Examples and Comparative Examples was fixed to a SUS plate with a double-sided tape (model number: No. 5000NS, manufactured by Nitto Denko Corporation). Next, an acrylic adhesive tape (model number: No. 31B, manufactured by Nitto Denko Corporation) was bonded to the surface (treated surface) of the sheet. Then, it was left at room temperature, and after 30 minutes, using a tensile tester (trade name: Tensilon Universal Material Tester, model number: RTC-1210A, manufactured by A & D Co., Ltd.), the sheet and the adhesive tape The adhesive strength was determined.

[Example 2]
The sputter etching process using O ₂ gas was performed in the same manner as in Example 1 except that the product of the process density and the process time was 10 J / cm ² . The obtained sheet was subjected to FT-IR measurement and water absorption evaluation in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
The ultrahigh molecular weight polyethylene porous sheet obtained in Example 1 was not subjected to plasma treatment. The obtained sheet was subjected to FT-IR measurement and water absorption evaluation in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
Example 1 was performed except that Ar gas was used for the sputter etching process. The obtained sheet was subjected to FT-IR measurement and water absorption evaluation in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
A hydrophilic UHMWPE porous sheet was obtained in the same manner as in Example 1 except that the antistatic treatment was performed on the UHMWPE porous sheet instead of performing the plasma treatment. As an antistatic treatment, a UHMWPE porous sheet was coated with a cationic antistatic agent (cationic surfactant, trade name: Elecnon OR-W, manufactured by Dainichi Seika Kogyo Co., Ltd.) by dipping. Specifically, deionized water was added to the cationic antistatic agent to prepare a 3% aqueous solution, and the obtained aqueous solution was coated on the porous sheet by dip coating and dried at 90 ° C. for 2 minutes. . The obtained hydrophilic UHMWPE porous sheet was subjected to FT-IR measurement and water absorption evaluation in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
As a material UHMWPE porous sheet, Sunmap LC-T (trade name, Nitto Denko Corporation) having an average pore diameter of 17 μm and a porosity of 30% was used. The sun map LC-T was subjected to antistatic treatment in the same manner as in Example 3. The obtained hydrophilic UHMWPE porous sheet was subjected to FT-IR measurement and water absorption evaluation in the same manner as in Example 1. The results are shown in Table 1.

[Examples 5 to 6]
As a UHMWPE porous sheet of material, Sunmap LC-T was used as in Example 3. Plasma treatment was performed in the same manner as in Example 1 except that the conditions were changed as shown in Table 1 in Sunmap LC-T. Next, the obtained porous sheet was subjected to antistatic treatment in the same manner as in Example 4. About each obtained hydrophilic UHMWPE porous sheet, it carried out similarly to Example 1, and measured the FT-IR and evaluated water absorption.

[Examples 7 to 8]
As a UHMWPE porous sheet of material, Sunmap LC-T was used in the same manner as in Example 3, and an antistatic treatment was performed. Subsequently, the obtained porous sheet was subjected to plasma treatment in the same manner as in Example 1 except that each condition was changed as described in Table 1. About each obtained hydrophilic UHMWPE porous sheet, it carried out similarly to Example 1, and measured the FT-IR and evaluated water absorption.

  From the results of Table 1, in each sheet of the examples, the hydrophilic functional group (OH) is not introduced to such an extent that it can be detected on the surface of the porous sheet (up to several tens of μm in the thickness direction from the surface). Regardless, it was confirmed that the absorption rate was 15 mm / 3 minutes or more. Moreover, the adhesive force of Example 3 was 0.6 N / mm, and Example 4 was 0.5 N / mm. Examples 1, 2, and 5 to 8 were 2.1 N / mm or more.

The hydrophilic ultrahigh molecular weight plastic porous sheet of the present invention has high water absorption, particularly in the case of a hydrophilic ultrahigh molecular weight plastic porous sheet using ultrahigh molecular weight polyethylene, and has high water absorption and is derived from polyethylene. Therefore, it can be used as a humidifier element such as a battery separator or an air conditioner, or an ink absorber of a printer, which is required to retain liquid water.

Claims (11)

The absorption rate when one end of a sheet is immersed in pure water in an atmosphere of 25 ° C. and humidity 60% RH is 15 mm / 3 min or more, and is composed of an ultra high molecular weight plastic. Infrared spectroscopy (FT-IR) The hydrophilic ultrahigh molecular weight plastic porous sheet, characterized in that no characteristic absorption is observed at 3000 to 3500 cm ⁻¹ in the IR spectrum measured by ( ¹ ).   The ultra high molecular weight plastic is at least one selected from the group consisting of ultra high molecular weight polyethylene, ultra high molecular weight polypropylene, ultra high molecular weight polyvinyl chloride, and ultra high molecular weight polyamide. Hydrophilic ultra high molecular weight plastic porous sheet.   The hydrophilic ultra high molecular weight plastic porous sheet according to claim 1, wherein the ultra high molecular weight plastic is ultra high molecular weight polyethylene.   2. The hydrophilic ultrahigh molecular weight plastic porous sheet according to claim 1, wherein an average pore diameter of the porous sheet is less than 20.0 μm.   The average pore diameter of the porous sheet is 5.0 to 15.0 µm, and the porosity is more than 30% and 80% or less, according to any one of claims 1 to 4. Hydrophilic ultra high molecular weight plastic porous sheet.   The hydrophilic ultrahigh molecular weight plastic porous sheet according to any one of claims 1 to 5, wherein the absorption rate is 20 mm / 3 minutes or more. A process of performing antistatic treatment and / or plasma treatment on the porous sheet;
The porous sheet is composed of ultra high molecular weight plastic, and the average pore diameter is less than 20.0 μm,
When the antistatic treatment is not performed, the plasma treatment is performed in an oxygen gas atmosphere, and when the antistatic treatment is performed before or after the plasma treatment, the plasma treatment is performed in an oxygen gas or argon gas atmosphere. The manufacturing method of the hydrophilic ultra high molecular weight plastic porous sheet as described in any one of Claims 1-6.   The method for producing a hydrophilic ultra-high molecular weight plastic porous sheet according to claim 7, wherein the plasma treatment is performed at a gas pressure of 0.5 to 10 Pa.   The method for producing a hydrophilic ultrahigh molecular weight plastic porous sheet according to claim 7 or 8, wherein an antistatic treatment is performed before or after the plasma treatment. The product of the plasma processing treatment density and processing time in the process of case without antistatic treatment, characterized in that at 10J / cm ² or more 300 J / cm ² or less, any one of the claims 7-9 The manufacturing method of the hydrophilic ultra high molecular weight plastic porous sheet as described in any one of. The product of the plasma treatment process density and the treatment time in the step of performing the antistatic treatment before and after the plasma treatment, and less than 0.10J / cm ² over 10J / cm ^2, claim 7 10. The method for producing a hydrophilic ultrahigh molecular weight plastic porous sheet according to any one of 9 above.