Porous material, and cleaning material comprising the porous material.

Abstract

To provide a novel porous material with antistatic properties. [Solution] This technology provides a porous body containing an ionomer and having continuous pores. The porous body may be obtained by extracting and removing the pore-forming material from a resin composition containing the ionomer and a pore-forming material. The porous body has a surface resistance value of 10 13 The ratio may be less than or equal to Ω / □. Furthermore, this technology also provides a cleaning material comprising the porous body.

Description

[Technical Field]

[0001] This technology relates to a porous body and a cleaning material comprising the porous body. [Background technology]

[0002] Currently, porous materials made of resin are used in a variety of fields. For example, they are used in functional separation membranes such as filters and filtration membranes, water-retaining materials, water-stopping materials, sustained-release materials, stamp pads using solvent-type inks, components that absorb and retain organic solvents, seepage pads, cosmetic tools, medical tools, abrasive materials, and cleaning materials.

[0003] Furthermore, technologies are being developed to impart additional properties to porous materials depending on their intended use. For example, Patent Document 1 describes a foam having a three-dimensional interconnected bubble structure in which the conductive substance is uniformly dispersed, obtained by heating a mixture of at least one type of thermoplastic resin, a water-soluble bubble-forming material that is thermally stable and maintains its shape at the temperature at which the thermoplastic resin melts, a water-soluble polymer compound that acts as a lubricant, and a conductive substance that imparts the desired conductivity to the final foam product, and then extracting and removing the water-soluble bubble-forming material and the water-soluble polymer compound with water, thereby obtaining a foam with a volume resistivity of 10 4 ~10 9 A conductive roll is disclosed, characterized in that its hardness is set within the range of Ω, and its Asker C hardness is set within the range of 20 to 40. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2003-241467 [Overview of the project] [Problems that the invention aims to solve]

[0005] As mentioned above, technologies for imparting new properties to porous materials are being developed, and technologies for imparting conductivity and antistatic properties using conductive fillers have been proposed. However, problems have arisen such as the absence of conductive fillers, uneven conductivity, and limitations in color.

[0006] Therefore, the main objective of this technology is to provide a novel porous material with antistatic properties. [Means for solving the problem]

[0007] In this technology, first, the ionomer is included, To provide a porous body having continuous pores. The porous material relating to this technology may be obtained by extracting and removing the pore-forming material from a resin composition containing the ionomer and the pore-forming material. The porous material relating to this technology has a surface resistance value of 10 13 It may be less than or equal to Ω / □. This technology also provides a cleaning material comprising the porous body. [Modes for carrying out the invention]

[0008] The following describes a preferred form for implementing this technology. The embodiments described below are examples of typical embodiments of this technology, and any combination of these embodiments is possible. Furthermore, this does not mean that the scope of this technology will be narrowed.

[0009] 1. Porous material The porous material related to this technology contains an ionomer and has continuous pores.

[0010] The porous material relating to this technology includes an ionomer. An "ionomer" is a general term for polymers in which ionic groups are introduced into a hydrophobic polymer main chain. Examples of ionsomers include copolymers of ethylene and unsaturated carboxylic acids neutralized with metal ions, and copolymers of polypropylene and unsaturated carboxylic acids neutralized with metal ions. Examples of such metal ions include potassium ions, sodium ions, zinc ions, and magnesium ions.

[0011] In this technology, among these, potassium ionomers of ethylene-unsaturated carboxylic acid copolymers are particularly preferred, and potassium ionomers of ethylene-(meth)acrylic acid random copolymers are especially preferred. Furthermore, the ionomer may be manufactured through any of the following manufacturing processes, such as melting or titration. Furthermore, commercially available products may also be used. Such ionomers are sold by companies such as Mitsui DuPont Polychemicals under product names such as "Entira MK400" and "Entira SD100".

[0012] Furthermore, the porous material related to this technology has continuous pores. "Continuous pores" refers to a structure in which pores are interconnected and form a network. As a result, it has superior air permeability and water permeability compared to closed pores, and can be made lighter.

[0013] The porous material according to this technology is obtained, for example, by extracting and removing the pore-forming material from a resin composition containing the ionomer and the pore-forming material. In the production of the porous material according to this technology, in addition to the ionomer and pore-forming material, other components such as a water-soluble polymer that acts as a lubricant and resin components other than the ionomer can be used depending on the purpose. The components used in the manufacture of the porous material related to this technology will be described in detail below.

[0014] (1) Ionomer The porous body according to the present technology is characterized by containing an ionomer as a resin component. Since the ionomer is as described above, the description thereof is omitted here.

[0015] The amount of the ionomer used in the production of the porous body according to the present technology can be freely set according to the purpose. The lower limit of the amount of the ionomer used in the raw material of the porous body is, for example, 1% by volume or more, preferably 3% by volume or more, more preferably 5% by volume or more. The upper limit of the amount of the ionomer used in the raw material of the porous body is, for example, 50% by volume or less, preferably 45% by volume or less, more preferably 40% by volume or less.

[0016] (2) Pore-forming material The pore-forming material that can be used in the present technology is preferably a substance that is soluble in water, alcohol, or an alcohol aqueous solution (preferably water) and is stable even when the ionomer melts. Specifically, for example, inorganic substances such as NaCl, KCl, CaCl, NH4Cl, NaNO3, and NaNO2; organic substances such as sodium salts of TME (trimethylolethane), trimethylolpropane, trimethylolbutane, sucrose, soluble starch, sorbitol, glycine, and various organic acids (for example, malic acid, citric acid, glutamic acid, succinic acid, succinic acid, etc.), and these can be used alone or in combination of two or more.

[0017] In the present technology, among these, it is particularly preferable to use an inorganic substance, and among the inorganic substances, it is particularly preferable to use NaCl.

[0018] The average particle diameter of the pore-forming material can be freely set as long as the effects and functions of the present technology are not impaired. The average particle diameter of the pore-forming material is preferably 2.5 μm to 300 μm, and within this range, surface properties, water permeability, etc. can be controlled, and a porous body suitable for the application can be provided.

[0019] In addition, the "average particle diameter of the pore-forming material" is the average particle diameter in the mixed state when two or more pore-forming materials having a single peak are mixed. Also, in the present technology, the "average particle diameter" refers to the particle diameter (D-50) at which the cumulative frequency becomes 50% in the particle size distribution measured by the laser diffraction method.

[0020] The amount of the pore-forming material used in the production of the porous body according to the present technology can be freely set as long as the functions and effects of the present technology are not impaired. The lower limit of the amount of the pore-forming material used in the raw material of the porous body is, for example, 45% by volume or more, preferably 50% by volume or more, and more preferably 55% by volume or more. The upper limit of the amount of the pore-forming material used in the raw material of the porous body is, for example, 80% by volume or less, preferably 75% by volume or less, and more preferably 70% by volume or less.

[0021] (3) Water-soluble polymer compound In the production of the porous body according to the present technology, a water-soluble polymer compound that acts as a lubricant may be used. Specifically, for example, polyethylene glycol derivatives such as polyethylene glycol, polyethylene oxide, polyethylene glycol diacrylate, polyethylene glycol dioleate, and polyethylene glycol diacetate can be mentioned, and one or a combination of two or more of these can also be used.

[0022] In the present technology, among these, it is particularly preferable to use polyethylene glycol. This is because polyethylene glycol has a high melt flow and high water solubility. When the molding is performed by an extrusion molding method, the molecular weight of polyethylene glycol is preferably 2,000 to 30,000, more preferably 5,000 to 25,000, and even more preferably 15,000 to 25,000.

[0023] The amount of water-soluble polymer compound used in the production of porous materials according to this technology can be freely set as long as it does not impair the function or effect of this technology. The lower limit of the amount of water-soluble polymer compound used in the raw materials of the porous material is, for example, 5% by volume or more, preferably 10% by volume or more, and more preferably 15% by volume or more. The upper limit of the amount of water-soluble polymer compound used in the raw materials of the porous material is, for example, 40% by volume or less, preferably 35% by volume or less, and more preferably 30% by volume or less.

[0024] (4)Thermoplastic resin The porous material relating to this technology may contain resins other than ionomers, for example, thermoplastic resins. Examples of thermoplastic resins include polyolefin resins, cellulose resins, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, (meth)acrylic resins, polyarylate resins, polystyrene resins, and polyvinyl alcohol resins, and it is possible to use one or more of these in combination.

[0025] Examples of olefin resins include ethylene resins, propylene resins, other α-olefin resins, ethylene-vinyl ester copolymers, ethylene-vinyl alcohol copolymers, partially hydrolyzed products of ethylene-vinyl ester copolymers, ethylene-(meth)acrylic acid (derivative) copolymers, ethylene-α-olefin-non-conjugated polyene copolymer rubber, and butyl rubber. These can be used individually or in combination of two or more types.

[0026] In this technology, it is particularly preferable to use α-olefin resin among these options.

[0027] The amount of thermoplastic resin used in the production of porous materials according to this technology can be freely set as long as it does not impair the function or effect of this technology. The lower limit of the amount of thermoplastic resin used in the raw materials of the porous material is, for example, 1% by volume or more, preferably 3% by volume or more, and more preferably 5% by volume or more. The upper limit of the amount of thermoplastic resin used in the raw materials of the porous material is, for example, 30% by volume or less, preferably 20% by volume or less, and more preferably 15% by volume or less.

[0028] (5) Others The porous material relating to this technology may be freely selected to contain one or more other components that can be used in general porous materials, as long as they do not impair the function or effect of this technology. For example, it may contain any components such as fillers, colorants, flame retardants, plasticizers, antistatic agents, antioxidants, ultraviolet absorbers, and antifungal agents.

[0029] 2. Method for manufacturing porous bodies The method for manufacturing a porous body according to this technology involves a process of extracting and removing a pore-forming material from a resin component. In this technology, it is possible to freely combine other processes that are carried out in general porous body manufacturing methods, as long as the function and effect of this technology are not impaired. For example, it can be manufactured by extracting and removing the pore-forming material and the water-soluble polymer compound from a molded body of a mixture of a resin component and, if necessary, other components, mixed with a pore-forming material and a water-soluble polymer compound. Heating may be performed during the mixing process as needed. In addition, each raw material of the porous body can be divided and mixed as needed.

[0030] More specifically, first, the resin components to be used as raw materials, and other components as needed, are mixed and kneaded in a predetermined mixing ratio using predetermined equipment. Then, this mixture is mixed and kneaded with one or more types of pore-forming materials and water-soluble polymer compounds in a predetermined mixing ratio using predetermined equipment to obtain a mixture. Next, the obtained mixture is molded into a molded body of a predetermined shape using an extruder or the like. The obtained molded body is then immersed in an extraction solvent at a predetermined temperature to extract and remove the pore-forming materials and water-soluble polymer compounds, thereby obtaining a porous body with numerous fine bubbles. The type of extraction solvent that can be used in this technology is not particularly limited and can be freely selected depending on the type of pore-forming material and water-soluble polymer compound used. Examples of extraction solvents include water.

[0031] For mixing and kneading the resin components, porosity-forming agents, and water-soluble polymer compounds mentioned above, kneading equipment such as laboplast mills, single-screw or twin-screw extruders, kneaders, pressure kneaders, conkneaders, Banbury mixers, Henschel mixers, and rotor mixers can be used. No special equipment is required for this kneading, and the kneading speed is not particularly limited. The temperature during kneading can be freely set depending on the melting point of the resins used. The kneading time depends on the physical properties of the mixture, but it is sufficient as long as the mixture is thoroughly mixed and kneaded. The kneaded raw materials can be molded into the desired shape by extrusion, injection molding, pressing, rolling, blow molding, etc.

[0032] The molded body, formed into the desired shape, is immersed in a solvent such as water for a predetermined time (depending on the shape and thickness of the molded body, for example, 24 to 48 hours) to extract and remove the pore-forming material and the water-soluble polymer compound. While any immersion method is acceptable, extraction and removal by immersion in water is preferred, as it brings the entire mixture into contact with the solvent. The temperature of the water used is not particularly limited as long as it is lower than the melting point of the resin used, but warm water at 15°C to 60°C may be used for efficient removal of the water-soluble substances.

[0033] As mentioned above, the porous material related to this technology does not use foaming agents, so it does not generate harmful substances (such as ammonia), thereby improving safety and reducing environmental impact. Furthermore, since the porous material related to this technology is not cross-linked, it has excellent reprocessability and can contribute to the achievement of the SDGs.

[0034] 3. Physical properties of porous materials (1) Surface resistance The upper limit of the surface resistance value of the porous material relating to this technology is not particularly limited, but for example, 10 13 It is less than or equal to Ω / □, preferably 10 12 The surface resistance is less than or equal to Ω / □. 13 When the surface resistance exceeds Ω / □, charge tends to accumulate in the porous material, causing it to become charged. There is no particular lower limit to the surface resistance of a porous material, but for example, 10 4 Ω / □ or greater, preferably 10 5 The resistance is greater than or equal to Ω / □. By setting the lower limit of the surface resistance of the porous material within this range, the risk of static charge buildup can be avoided.

[0035] In this technology, the surface resistance of the porous material is calculated using a surface resistance meter by passing an electric current through the surface and analyzing the resulting voltage.

[0036] (2) Porosity The upper limit of the porosity of the porous material relating to this technology is not particularly limited, but for example, it is 95% or less, preferably 90% or less. Setting the upper limit of the porosity of the porous material within this range prevents a decrease in the formability of the porous material and facilitates the manufacture of porous materials of excellent quality. The lower limit of the porosity of the porous material is not particularly limited, but for example, it is 50% or more, preferably 55% or more, and more preferably 60% or more. Setting the lower limit of the porosity of the porous material within this range improves solvent impregnation, and for example, when the porous material is used as a cleaning material, the cleaning solvent can penetrate sufficiently into the interior of the porous material, improving the cleaning effect.

[0037] In this technology, the porosity of the porous material is the value calculated using the method described in the examples below.

[0038] (3) Asker F hardness, Asker C hardness The surface hardness of the porous material according to this technology can be freely set as long as it does not impair the function or effect of this technology. In the surface hardness of the porous material according to this technology, the upper limit of the Asker F hardness is, for example, 75 or less, preferably 70 or less, and more preferably 65 or less. Similarly, the upper limit of the Asker C hardness is, for example, 70 or less, more preferably 65 or less, and even more preferably 60 or less. By setting the upper limit of the Asker F hardness or Asker C hardness of the porous material within this range, it is possible to prevent the porous material from becoming too hard, and, for example, to prevent scratching the object being cleaned when the porous material is used as a cleaning material.

[0039] Furthermore, regarding the surface hardness of the porous material according to this technology, the lower limit of the Asker F hardness is, for example, 40 or higher, preferably 45 or higher, and more preferably 50 or higher. Similarly, the lower limit of the Asker C hardness is, for example, 40 or higher, more preferably 45 or higher, and even more preferably 50 or higher. By setting the lower limit of the Asker F hardness or Asker C hardness of the porous material within this range, the strength of the porous material can be maintained and its durability can be further improved.

[0040] In this technology, the Asker F hardness of the porous material is measured using an F-type hardness tester in accordance with JIS K 6253-3. The Asker C hardness of the porous material is measured using a C-type hardness tester in accordance with JIS K 7312.

[0041] (4) Cell diameter The cell diameter of the porous material relating to this technology can be freely set as long as it does not impair the function or effect of this technology. The upper limit of the cell diameter of the porous material relating to this technology is not particularly limited, but for example, it is 300 μm or less, preferably 250 μm or less. Setting the upper limit of the cell diameter of the porous material within this range makes it easy to manufacture a porous material of excellent quality. The lower limit of the porosity of the porous material is not particularly limited, but for example, it is 2.5 μm or more, preferably 5 μm or more, and more preferably 7.5 μm or more. Setting the lower limit of the porosity of the porous material within this range makes it easy to manufacture a porous material of excellent quality.

[0042] In this technology, the cell diameter is the value calculated using the method described in the examples below.

[0043] (5) Hydrophilicity (contact angle) The hydrophilicity (contact angle) of the porous material related to this technology can be freely set as long as it does not impair the function or effect of this technology. The upper limit of the contact angle of the porous material related to this technology is not particularly limited, but for example, it is 90 degrees or less, preferably 85 degrees or less, and more preferably 80 degrees or less. Setting the upper limit of the contact angle within this range makes it less likely for liquids to be repelled, and improves compatibility with cleaning liquids when used for cleaning, etc. The lower limit of the contact angle is not particularly limited.

[0044] In this technology, the hydrophilicity (contact angle) is a value measured according to the method compliant with JIS R3257.

[0045] 4. Applications of porous materials The porous material related to this technology can be used in all fields and for all applications due to its high quality. In particular, because this technology does not involve the addition of conductive fillers, there is no possibility of secondary contamination due to the absence of conductive fillers, no unevenness in conductivity, and no color limitations imposed by conductive fillers, making it suitable for use as a cleaning material.

[0046] Furthermore, this technology can also employ the following configurations. [1] A porous body containing an ionomer, having continuous pores. [2] The porous body according to [1], obtained by extracting and removing the pore-forming material from a resin composition containing the ionomer and a pore-forming material. [3] The surface resistance value is 10 13 Ω / □ or less, the porous body according to [1] or [2]. [4] A cleaning material comprising the porous body according to [1] to [3]. [Examples]

[0047] Hereinafter, the present technology will be described in more detail based on examples. The examples described below show an example of a typical example of the present technology, and the scope of the present technology is not construed narrowly thereby.

[0048] (1) Production of porous body After weighing each raw material shown in Tables 1 and 2 below, they were kneaded with a lab plastomill (temperature: 140 °C, time: 10 min, rotation speed: 50 rpm). The kneaded mixture was hot-pressed with a hand press machine (temperature: 140 °C, time: 3 min), cooled and pressed (3 min), then water-cooled and immersed in water, and the pore-forming material and the water-soluble polymer compound were eluted overnight (temperature: about 25 °C) and dried to produce each porous body. The sheet width of each porous body was formed to be 100 × 150 mm, and the sheet thickness was 2 mm.

[0049] (2) Physical property measurement and evaluation For each of the produced porous bodies, physical property measurement and evaluation were performed using the following methods.

[0050] [Surface resistance value] The surface resistance value (Ω / □) of each porous body was calculated from the current and voltage on the surface by flowing a current through the surface using a surface resistance meter (surface meter).

[0051] [Porosity] The porosity (%) was calculated using the following formula: the apparent density of each porous material, measured in accordance with JIS K7222, was divided by the density of the resin component, this divisor was subtracted from 1, and the result was multiplied by 100 to obtain the percentage. Porosity (%) = {1 - (Apparent density of porous material) ÷ ​​(Density of resin component)} × 100 (%)

[0052] [Asker F hardness] [Asker C hardness] Asker F hardness was measured using a method compliant with JIS K 6253-3. Asker C hardness was measured according to the method compliant with JIS K 7312.

[0053] [Cell diameter] The cell diameter (μm) was calculated based on the particle size of the sodium chloride (NaCl) used as the raw material.

[0054] [Hydrophilicity (contact angle)] Hydrophilicity (contact angle) (degrees) was measured according to the method compliant with JIS R3257.

[0055] (3) Results The results are shown in Tables 1 and 2 below.

[0056] [Table 1]

[0057] [Table 2]

[0058] (4) Discussion As shown in Tables 1 and 2 above, it was found that by including an ionomer and having continuous pores, excellent surface resistance values ​​can be obtained even without using conductive fillers. On the other hand, Comparative Example 1, which did not contain an ionomer, resulted in an excessively high surface resistance value. Furthermore, Comparative Example 2 was unmold, and none of the measurements could be performed.

Claims

1. Contains ionomers, A porous body having continuous pores.

2. A porous body according to claim 1, obtained by extracting and removing the pore-forming material from a resin composition containing the ionomer and the pore-forming material.

3. The surface resistance value is 10 １３ The porous body according to claim 1, wherein the ratio is Ω / □ or less.

4. A cleaning material comprising the porous body described in claims 1 to 3.

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