WO2015115289A1 - Porous film, moisture-permeable waterproof sheet, complex, and protective clothing - Google Patents

Abstract

The objective is to provide a porous film that is suitable as a base material for a protective clothing having excellent water pressure resistance and wearing comfort by reducing the internal heating of the worn clothing, as well as a moisture-permeable waterproof sheet and a protective clothing using the porous film. The objective is achieved with a porous film wherein the moisture permeability is 250 g/m²∙h or greater, the sum of the degrees of tensile elongation in the length direction and the width direction of the film is 100 to 500%, the water pressure resistance is 4,500 mm H₂O or greater, and the ash content after incineration at a temperature of 850°C (JIS L 1013) is 0.5% by mass or less.

Description

Porous film, moisture permeable tarpaulin, composite and protective clothing

The present invention relates to a porous film having excellent water pressure resistance and moisture permeability, high elongation, and excellent laminating properties with a nonwoven fabric. Further, by using the porous film, the present invention relates to a moisture permeable waterproof sheet, a composite, and protective clothing that are excellent in water pressure resistance and moisture permeability, have high elongation, reduce stuffiness when worn, and have excellent clothing comfort. .

Conventionally, as a fabric for waterproof sheets and waterproof clothes, a material obtained by coating or bonding a water-repellent resin to a fabric is often used because it is excellent in water resistance and processability. However, since conventional materials are inferior in moisture permeability or air permeability, moisture is trapped inside the protective clothing in a hot and humid working environment, causing discomfort, and when used as a waterproof sheet, There was a problem that mold and the like occurred.

As a solution to these problems, a laminated cloth in which a porous resin film is laminated on a fiber material cloth has been proposed (see, for example, Patent Document 1).

In addition, a cloth made of a moisture permeable film and a nonwoven fabric has been proposed (see, for example, Patent Documents 2, 3, and 4).

Also, a moisture permeable film that does not use inorganic particles such as calcium carbonate or organic particles has been proposed (for example, Patent Documents 5, 6, and 7).

JP 2001-38839 A JP-A-6-316022 JP 2003-145697 A JP-A-8-53561 JP 2006-28495 A JP 2001-342272 A Japanese Patent Laid-Open No. 9-3226

In Patent Document 1, as a laminated fabric, a technique in which a porous resin film is formed by applying and drying a coating material in which silica or zeolite or the like is added to a polyurethane resin as an adsorbent in an amount of 10% by weight or more is dried. However, there is a problem that the elongation of the film is low and it is easily broken when laminating or wearing clothes.

Further, in the techniques proposed in Patent Documents 2, 3 and 4, since a film made by stretching a resin sheet in which a large amount of inorganic particles such as calcium carbonate and organic particles are added and mixed is made porous, There is a problem that the compressibility is insufficient, the mechanical elongation is anisotropic, the elongation at break of the fabric is low, and the particles are the starting point when wearing clothes and are easily broken. Furthermore, since the film is not thin (the rigidity of the film is not sufficient), there is a problem that the process passability in the process of bonding to the nonwoven fabric is inferior.

In the techniques proposed in Patent Documents 5, 6 and 7, the moisture permeability is inferior, so that moisture is trapped inside the protective garment in a high-temperature and high-humidity working environment, causing discomfort or waterproofing. When used for a sheet, there is a problem that mold or the like is generated inside, or there is anisotropy in mechanical elongation, and there is a problem that the breaking elongation of the fabric is low and it is easily broken when wearing clothes.

The object of the present invention is to solve the above-mentioned problems. In other words, it is excellent in water pressure and moisture permeability, high in elongation, excellent in laminating properties with non-woven fabric, reduced in stuffiness when worn, and suitable for protective clothing base materials with excellent clothing comfort. It is to provide an adhesive film and a moisture permeable waterproof sheet, a composite, and protective clothing using the same. Furthermore, another object is to provide a moisture permeable waterproof sheet and protective clothing with very little incineration residue when no longer needed.

That is, an object of the present invention is to provide a porous film having excellent water pressure resistance and moisture permeability, high elongation, excellent laminating property with a non-woven fabric, hardly torn, and excellent process passability. . Another object of the present invention is to provide a moisture-permeable waterproof sheet, a composite, and protective clothing using the porous film, which has excellent water pressure resistance, high elongation, reduces the feeling of stuffiness when worn, and is excellent in clothing comfort. . Another object of the present invention is to provide a moisture-permeable waterproof sheet and protective clothing that have very little residue (ash) when incinerated when no longer needed.

The above-mentioned problems are that the moisture permeability is 250 g / m ² · h or more, the sum of the tensile elongation in the longitudinal direction and the width direction of the film is 100 to 500%, and the water pressure resistance is 4,500 mmH ₂ O or more. In addition, it can be achieved by a porous film having an ash content (JIS L 1013) after incineration at a temperature of 850 ° C. of 0.5% by mass or less.

The porous film of the present invention is excellent in water pressure resistance, reduces the feeling of stuffiness when worn, and is suitable for a base material of a protective garment excellent in clothes comfort and a moisture-permeable waterproof sheet using the same, Complexes and protective clothing can be provided.

The present invention can provide a porous film excellent in water pressure resistance and moisture permeability. Since the breaking elongation is high, it is possible to provide a porous film excellent in laminate processability (that is, process passability) with a nonwoven fabric. Further, by using the porous film, it is possible to provide a moisture permeable waterproof sheet, a composite, and protective clothing that are excellent in water pressure resistance, reduce the feeling of stuffiness when worn, and have excellent clothing comfort. Furthermore, it is possible to provide a moisture-permeable waterproof sheet and protective clothing that have very little ash after incineration when it is no longer needed.

The porous film of the present invention is a film having many fine through-holes penetrating both surfaces of the film and having air permeability. The resin constituting the porous film may be any of polyolefin resin, polycarbonate, polyamide, polyimide, polyamideimide, aromatic polyamide, fluorine resin, etc., but heat resistance, moldability, production cost reduction, chemical resistance, A polyolefin resin is desirable from the viewpoint of oxidation resistance and reduction resistance. Therefore, the porous film of the present invention preferably contains a polyolefin resin.

Examples of the monomer component constituting the polyolefin resin include ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-pentene, 3-methyl-1-butene, 1-hexene and 4-methyl. -1-pentene, 5-ethyl-1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, vinyl And cyclohexene, styrene, allylbenzene, cyclopentene, norbornene, 5-methyl-2-norbornene, and the like. These homopolymers and at least two or more types of copolymers selected from the above monomer components, Examples include, but are not limited to, blends of copolymers and copolymers. In addition to the above monomer components, for example, vinyl alcohol, maleic anhydride or the like may be copolymerized or graft polymerized, but is not limited thereto. As the base material of the moisture permeable waterproof sheet, polyethylene using ethylene as a monomer component and / or polypropylene using propylene as a monomer component is preferable. Propylene is particularly preferable from the viewpoint of heat resistance, air permeability, porosity, and the like. Polypropylene using as a monomer component is preferable, and the main component is preferable. Therefore, it is particularly preferable that the porous film of the present invention contains a polyolefin resin, and the polyolefin resin is polypropylene. The “main component” means that the proportion of a specific component in all components is 50% by mass. % Or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and most preferably 95% by mass or more. In addition, although an upper limit is not specifically limited, 100 mass% becomes a substantial upper limit.

As a method for forming the through-hole in the porous film, either a wet method or a dry method may be used. Specifically, the wet method means that a polyolefin resin is used as a matrix resin, an extractable to be extracted after sheeting is added, and the mixed resin composition is made into a sheet, and then the additive is used using a good solvent of the extractable. This is a method in which voids are generated in the matrix resin by extracting only.

On the other hand, the dry method is, for example:
By adopting low temperature extrusion and high draft ratio at the time of melt extrusion, the lamella structure in the film before stretching is controlled, and this is uniaxially stretched after heat treatment to generate cleavage at the lamella interface, and voids are created. Forming method (so-called lamellar stretching method);
A method of forming voids by adding a large amount of incompatible resin as particles to polypropylene, which is an inorganic particle or matrix resin, forming a sheet and stretching it to cause cleavage at the interface between the particle and the polypropylene resin (particle method) , Phase separation method); and a method of forming voids in the film by utilizing the crystal density difference and crystal transition between α-type crystal (α crystal) and β-type crystal (β crystal), which are polymorphs of polypropylene ( (So-called β crystal method)
This means all methods that do not use solvent extraction. Among these methods, it is preferable in terms of productivity to employ a dry method, particularly a β crystal method.

In order to form through holes in the film using the β crystal method, the β crystal forming ability of the porous film is preferably 40% or more. If the β-crystal forming ability is less than 40%, the amount of β-crystals is small at the time of film production, so the number of voids formed in the film is reduced by utilizing the transition to α-crystal, and as a result, only a film with low permeability is obtained. It may not be possible. On the other hand, the upper limit of the β-crystal forming ability is not particularly limited, but it exceeds 99.9% by adding a large amount of the β-crystal nucleating agent described later or the stereoregulation of the polypropylene resin to be used. The industrial practical value is low, for example, the film forming stability is lowered. Industrially, the β-crystal forming ability is preferably 65 to 99.9%, particularly preferably 70 to 95%.

In order to control the β-crystal forming ability to 40% or more, a polypropylene resin with a high isotactic index is used, or a β crystal is selectively formed by adding it to a polypropylene resin called a β crystal nucleating agent. The crystallization nucleating agent to be used is preferably used as an additive. Examples of β crystal nucleating agents include alkali or alkaline earth metal salts of carboxylic acids such as calcium 1,2-hydroxystearate and magnesium succinate, and N, N′-dicyclohexyl-2,6-naphthalenedicarboxyamide. Amide compounds, tetraoxaspiro compounds such as 3,9-bis [4- (N-cyclohexylcarbamoyl) phenyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, benzenesulfonic acid Preferable examples include aromatic sulfonic acid compounds such as sodium and sodium naphthalene sulfonate, imide carboxylic acid derivatives, phthalocyanine pigments, and quinacridone pigments. Particularly, amides disclosed in JP-A-5-310665 are preferred. Compounds can be preferably usedThe addition amount of the β crystal nucleating agent is preferably 0.05 to 0.5% by mass, more preferably 0.1 to 0.3% by mass, based on the polypropylene composition. If it is less than 0.05% by mass, formation of β crystals becomes insufficient, and the air permeability of the porous film may be lowered. If it exceeds 0.5% by mass, coarse voids are formed, and physical property changes during application of organic solvents and drying may increase. In addition, in this invention, a polypropylene composition is a composition containing all the materials which comprise porous films, such as a beta crystal nucleating agent and antioxidant, in addition to a polypropylene resin.

The polypropylene resin constituting the porous film of the present invention preferably has a melt flow rate (hereinafter referred to as MFR, measurement conditions are 230 ° C., 2.16 kg) in the range of 2 to 30 g / 10 min. It is preferable that it is an isotactic polypropylene resin. When the MFR is less than 2 g / 10 minutes, the melt viscosity of the resin becomes high and high-precision filtration becomes difficult, and the quality of the film may be lowered. When the MFR exceeds 30 g / 10 min, the molecular weight becomes too low, so that the film is easily broken during stretching, and the productivity may be lowered. More preferably, the MFR is 3 to 20 g / 10 minutes.

In the case of using an isotactic polypropylene resin, the isotactic index is preferably 90 to 99.9%, more preferably 95 to 99%. If the isotactic index is less than 90%, the crystallinity of the resin is low, and it may be difficult to achieve high air permeability.

In the case of using a polypropylene resin in the present invention, not only a homopolypropylene resin can be used, but also from the viewpoint of stability in the film-forming process, film-forming properties, and uniformity of physical properties, an ethylene component or butene is added to polypropylene. A resin obtained by copolymerizing an α-olefin component such as hexene or octene in an amount of 5% by mass or less, more preferably 2.5% by mass or less can be used. The form of introduction of the comonomer (copolymerization component) into polypropylene may be either random copolymerization or block copolymerization.

In addition, it is possible to add polypropylene (high MFR polypropylene) having an MFR of 70 g / 10 minutes or more, preferably 100 g / 10 minutes or more, more preferably 500 g / 10 minutes or more to the polypropylene resin described above in terms of improving moisture permeability. preferable. The upper limit of MFR is preferably 5000 g / 10 min or less. If the MFR exceeds 5000 g / 10 min, it may be difficult to make it uniform with the above-mentioned isotactic polypropylene. Usually, high MFR polypropylene (especially isotactic polypropylene) having an MFR of 70 g / 10 min or more has not been used in the field of films because it has poor stretchability and causes a decrease in elongation. However, when the polypropylene composition is 100% by mass, the high MFR polypropylene is contained in an amount of 0.1 to 20% by mass, preferably 0.5 to 10% by mass, more preferably 0.7 to 5% by mass. The high MFR polypropylene added in a small amount increases the molecular chain end concentration at the crystal interface and promotes pore formation at the crystal interface in the longitudinal stretching, that is, it acts as a pore opening aid, resulting in uniform pore opening. While having water pressure resistance and elongation, it can have moisture permeability and can achieve conflicting properties.

In the polypropylene resin that forms the porous film of the present invention, an antioxidant, a heat stabilizer, a light stabilizer, a neutralizer, an antistatic agent and a lubricant composed of organic particles, as long as the effects of the present invention are not impaired. Furthermore, you may contain various additives, such as an antiblocking agent, a filler, and an incompatible polymer. In particular, it is preferable to add an antioxidant for the purpose of suppressing the oxidative deterioration due to the heat history of the polypropylene resin, but when the polypropylene composition is 100% by mass, the antioxidant addition amount is 2% by mass or less. More preferably, it is 1 mass% or less, More preferably, it is 0.5 mass% or less. On the other hand, when a filler is contained, it may fall off, which may adversely affect the work, and the filler may be the starting point and the elongation may be lowered. In particular, the inorganic filler is preferably not added because it remains as ash after incineration.

The porous film of the present invention has a moisture permeability of 250 g / m ² · h or more. When the moisture permeability is less than 250 g / m ² · h, when the porous film of the present invention is worn as protective clothing, the feeling of stuffiness may be felt strongly, and the clothing comfort may be low. From the viewpoint of achieving both water pressure resistance and elongation, the moisture permeability is preferably high, but the upper limit is practically 2,000 g / m ² · h. From the viewpoint of clothing comfort, the moisture permeability is preferably 250 to 2,000 g / m ² · h, more preferably 300 to 2,000 g / m ² · h, and further preferably 350 to 2,000 g / m ² · h. preferable. The moisture permeability is adjusted by adjusting the amount of β-crystal nucleating agent added in the raw material, the amount of high MFR polypropylene added in the raw material, adjusting the stretching ratio and temperature in the longitudinal direction, re-stretching, and re-stretching. It can be controlled by adjusting the stretching temperature and the magnification. For example, the addition amount of the β crystal nucleating agent in the raw material is further increased within the range of 0.05 to 0.5% by mass, the temperature of the cast drum is increased within the range of 105 to 130 ° C., Increase the moisture permeability by increasing the amount of high MFR polypropylene in the range of 0.1 to 20% by mass or lowering the longitudinal stretching temperature in the range of 90 to 140 ° C. The moisture permeability can be increased by increasing the draw ratio in the longitudinal direction within a range of 3 to 7 times. Further, the film stretched in the longitudinal direction and the width direction is re-stretched in the longitudinal direction, and the re-stretching stretching temperature is lowered within the range of 130 to 170 ° C., or the re-stretching stretching ratio is 1.02. Moisture permeability can be increased by stretching at a high magnification within a range of up to 2.0 times.

In the porous film of the present invention, the sum of the tensile elongation in the longitudinal direction and the width direction of the film is 100 to 500%. When the sum of the tensile elongation in the longitudinal direction and the width direction of the film is less than 100%, in the case of the protective clothing based on the porous film of the present invention, the porous film breaks during the operation, and the water pressure resistance decreases. When water leaks or the porous film of the present invention is used as a base material for protective clothing, the process passability may be inferior in the process of bonding to a nonwoven fabric. When the sum of the tensile elongation in the longitudinal direction and the width direction of the film is higher than 500%, the process passability in processing such as stretching of the film when tension is applied in the processing step may be inferior. From the viewpoint of workability and workability in the field and because the porous film stretches during processing and the water pressure resistance decreases, the sum of the tensile elongation in the longitudinal direction and the width direction of the film is preferably 100 to 400%. 130 to 400% is more preferable, and 150 to 400% is more preferable. The sum of the tensile elongation in the longitudinal and width directions of the film is to adjust the temperature of the cast drum, the stretching ratio and temperature and stretching speed in the longitudinal direction, the stretching speed and magnification in the width direction, and the temperature and time in the heat treatment process. In particular, it can be easily controlled by the redrawing temperature and the magnification in the longitudinal direction. The sum of the tensile elongation in the longitudinal direction and the width direction of the film is, for example, higher in the temperature of the cast drum in the range of 105 to 130 ° C. or more in the range of 90 to 140 ° C. in the longitudinal direction. The stretching ratio in the longitudinal direction is in the range of 3 to 7 times, and the moisture permeability value is lowered to such a degree as to satisfy the above-mentioned preferable numerical range, or the stretching speed in the longitudinal direction is set to 200. By increasing the speed within the range of 1,000 to 1,000,000% / min, the sum of the tensile elongation in the longitudinal direction and the width direction of the film can be increased. Further, the draw ratio in the width direction is in the range of 4 to 15 times, and the water pressure resistance value is lowered to a value that satisfies a suitable numerical range described later, or the draw speed in the width direction is set to 500 to 10, Accelerating within the range of 000% / min, increasing the heat treatment temperature in the heat treatment step before the relaxation treatment, and heat treatment temperature in the heat treatment step after the relaxation treatment within the range of 140 to 170 ° C, or relaxing treatment The heat treatment time in the previous heat treatment step and the heat treatment time in the heat treatment step after the relaxation treatment are made longer in the range of 0.1 to 10 seconds, or the draw ratio of redrawing is 1.02 to 2.0. By stretching at a low magnification within the range of double, the sum of the tensile elongation in the longitudinal direction and the width direction of the film can be increased. In particular, by performing re-stretching in the longitudinal direction and increasing the re-stretching temperature to 130 ° C. or higher so that the film does not melt, the sum of the tensile elongation in the longitudinal direction and the width direction of the film can be increased.

The porous film of the present invention has a water pressure resistance of 4,500 mmH ₂ O or more. If the water pressure resistance is less than 4,500mmH ₂ O, when used as protective clothing, water may permeate when it is in strong rain and wind, with elbows, knees, or sitting down. If so, water may soak in and mold may form inside. The upper limit of the water pressure resistance is preferably 25,000 mmH ₂ O from the viewpoint of moisture permeability. From the viewpoint of workability and workability on site, the water pressure resistance is preferably 5,000 to 25,000 mmH ₂ O, and more preferably 8,000 to 25,000 mmH ₂ O. The water pressure resistance is adjusted by adjusting the temperature of the cast drum, the stretching ratio and temperature and stretching speed in the longitudinal direction, the stretching speed and magnification in the width direction, the temperature and time in the heat treatment process, and the relaxation rate in the relaxation process. It can be controlled by stretching, adjusting the redrawing temperature and magnification, and adjusting the temperature of the heat treatment after redrawing. For example, the water pressure can be increased by increasing the temperature of the cast drum within the range of 105 to 130 ° C., or by increasing the stretching temperature in the longitudinal direction within the range of 90 to 140 ° C. The stretching ratio is increased within the range of 3 to 7 times, the longitudinal stretching speed is increased within the range of 200,000 to 1,000,000% / min, or the stretching speed in the width direction is increased. Faster within the range of 500 to 10,000% / min, higher draw ratio in the width direction within the range of 4 to 15 times, heat treatment temperature in the heat treatment process before relaxation treatment and after relaxation treatment The heat treatment in the heat treatment step is set to a higher temperature within the range of 140 to 170 ° C., or the heat treatment time in the heat treatment step before the relaxation treatment or the heat treatment time in the heat treatment step after the relaxation treatment is 0.1 to 10 seconds. Within a longer range Ri, it is possible to increase the water pressure by a higher relaxation rate in the relaxation process in the range of 5 to 35%. Further, the stretching temperature at the time of re-stretching in the longitudinal direction and / or the width direction is set to a high temperature such that the film does not melt within the range of 130 to 170 ° C., or the stretching ratio of re-stretching is 1.02 to 2.0 times. The water pressure resistance can be increased by stretching at a high magnification within the range, or by increasing the temperature of the heat treatment after re-stretching within a range of 145 to 175 ° C. so that the film does not melt.

As a method of obtaining the porous film of the present invention by balancing moisture permeability, water pressure resistance, and the balance of properties of the sum of tensile elongation in the longitudinal direction and width direction of the film, the amount of β crystal nucleating agent added in the raw material is adjusted. Adjusting the amount of high MFR polypropylene added to the raw material, adjusting the temperature of the cast drum, adjusting the stretching ratio and temperature and the stretching speed in the longitudinal direction, and the stretching speed in the width direction Adjusting the magnification, adjusting the temperature and time in the heat treatment step, adjusting the relaxation rate in the relaxation treatment step, performing re-stretching, and setting the re-stretching temperature and magnification within the ranges described below, and It can control by making the heat processing temperature after redrawing into the below-mentioned range.

In particular, in obtaining the porous film of the present invention, adjusting the addition amount of the β crystal nucleating agent in the raw material, adjusting the temperature of the cast drum, adjusting the stretching ratio, temperature and stretching speed in the longitudinal direction. The balance of characteristics is insufficient by adjusting only the process conditions such as adjusting the magnification in the width direction, adjusting the temperature and time in the heat treatment step, and adjusting the relaxation rate in the relaxation treatment step. .

Therefore, a specific amount of high MFR polypropylene (especially high MFR isotactic polypropylene) is included in the raw material, the stretching speed in the width direction is within the range described below, re-stretching, and the re-stretching temperature and magnification are within the range described below. However, it is important to achieve both the moisture permeability, the water pressure resistance, and the balance of properties of the sum of the tensile elongation in the longitudinal direction and the width direction of the film for the first time. As described above, the content of the high MFR polypropylene is preferably 0.1 to 20% by mass.

The porous film of the present invention has an ash content (JIS L1013) after incineration at a temperature of 850 ° C. of 0.5% by mass or less. If the ash content after incineration at a temperature of 850 ° C. is more than 0.5% by mass, ash content is generated by incineration for disposable use. In the case of protective clothing, ash content may be further processed for safety and health. . The lower limit of the ash content after incineration at a temperature of 850 ° C. is ideally 0%, but is substantially about 0.01%. In order to reduce the ash content after incineration at a temperature of 850 ° C. to 0.5% by mass or less, it can be achieved by making the raw material porous by a method in which inorganic particles are not added.

The porous film of the present invention preferably has a tensile elongation ratio in the (longitudinal direction / width direction) of 0.6 to 1.5. Here, “the tensile elongation ratio in the (longitudinal direction / width direction) of the film” means the ratio of the tensile elongation in the film longitudinal direction to the tensile elongation in the film width direction (that is, tensile elongation / longitudinal / (Tensile elongation in the width direction). That is, in the porous film of the present invention, the ratio of the tensile elongation in the longitudinal direction to the tensile elongation in the width direction of the film (tensile elongation in the longitudinal direction / tensile elongation in the width direction) is 0.6 to 1.5. It is preferable that When the ratio of the tensile elongation in the longitudinal direction to the tensile elongation in the width direction of the film is less than 0.6 or greater than 1.5, when the porous film is used as a base material for protective clothing, the porous film is anisotropic. There is a case where the water pressure resistance is lowered due to easy tearing in one direction at the time of work and detachment or high elongation in one direction. From the viewpoint of water pressure resistance, the ratio is more preferably 0.6 to 1.4, and even more preferably 0.7 to 1.3.

The basis weight of the porous film of the present invention is preferably 5 g / m ² or more. When the basis weight is less than 5 g / m ² , the elongation of the film, for example, the tensile elongation is low, and in the case of a protective garment based on the porous film of the present invention, the porous film breaks during work, The water pressure resistance is lowered, water leakage occurs, or the process passability in the process of bonding the porous film of the present invention to a nonwoven fabric may be inferior. The upper limit of the basis weight is actually 40 g / m ² . Basis weight, from the viewpoint of tensile elongation and wear, preferably 5 ~ 30g / ^{m 2,} more preferably 5 ~ 20g / ^{m 2,} more preferably 8 ~ 15g / ^{m 2.}

In this invention, it is preferable to comprise a moisture-permeable waterproof sheet using the above-mentioned porous film. Moreover, in this invention, the composite_body | complex of fiber layers, such as this moisture-permeable waterproof sheet and a nonwoven fabric, can also be comprised. In the present invention, a preferable composite is a composite of the moisture permeable waterproof sheet and the nonwoven fabric. The basis weight of the composite of the present invention is preferably 100 g / m ² or less, more preferably 50 g / m ² or less, and further preferably 45 g / m ² or less. In the case of a protective clothing composed of a composite of a moisture permeable waterproof sheet and a fiber layer (nonwoven fabric), if the basis weight is larger than 50 g / m ² , the clothing becomes heavy and the comfort of clothing may be reduced. In particular, when the basis weight is larger than 100 g / m ² , the tendency becomes more remarkable. The lower limit of the basis weight is preferably 25 g / m ² or more from the viewpoint of the strength of the composite.

The porous film of the present invention preferably has a film thickness of 5 μm or more. If the thickness is less than 5 μm, the film may break during processing or use. The film thickness is more preferably 10 μm or more, and even more preferably 10 to 50 μm.

Hereinafter, the method for producing the porous film of the present invention will be described based on a specific example. In addition, the manufacturing method of the porous film of this invention is not limited to this.

When two or more polypropylene resins are used as raw materials, there are dry blending, melt blending, etc. as a method for mixing the resin raw materials. However, in the present invention, the viscosity of the polypropylene resin used may be greatly different. When mixed, resins having different viscosities are dispersed unevenly in the sheet when formed into a sheet, and the sheet characteristics may be insufficient. In the present invention, it is preferable to employ melt blending as a method for mixing the resin raw materials. Extruders used in melt blending may be either single-screw extruders or twin-screw extruders, but they can be mixed at high shear, and the mixing ratio is easily controlled to be uniform, raw material uniformity, resin deterioration suppression, and production. It is preferable to carry out with a twin screw extruder from a viewpoint of property. Moreover, in order to control a dispersion state, you may melt-knead in multiple times with a twin-screw extruder.

As polypropylene resin, 96.5 parts by mass of homopolypropylene resin with MFR 4 g / 10 min, 3 parts by mass of high MFR polypropylene resin with MFR 1,000 g / 10 min, and N, N′-dicyclohexyl-2,6-naphthalene as β crystal nucleating agent The raw material is supplied from the measuring hopper to the twin screw extruder so that 0.3 parts by mass of dicarboxamide and 0.2 parts by mass of the antioxidant are mixed at this ratio, and then melt-kneaded and discharged from the die in a strand shape. Then, it is cooled and solidified in a 25 ° C. water tank, and cut into chips to prepare a polypropylene raw material (propylene composition). At this time, the melting temperature is preferably 280 to 310 ° C.

Subsequently, the film forming method of the porous film of the present invention will be described, but the following film forming method can also be applied when a raw material other than the above-mentioned polypropylene raw material is used.

Supplied polypropylene raw material to a single screw extruder and melt extruded at 200-230 ° C. And after removing a foreign material, a modified | denatured polymer, etc. with the filter installed in the middle of the polymer pipe | tube, it discharges on a cast drum from T-die, and an unstretched cast film is obtained. The cast drum preferably has a surface temperature of 105 to 130 ° C. from the viewpoint of controlling the β crystal fraction of the cast film to be high. At this time, since the molding of the end portion of the cast film particularly affects the subsequent stretchability, it is preferable that the end portion is sprayed with spot air to be brought into close contact with the drum. Moreover, you may spray air on the whole surface using an air knife from the close_contact | adherence state on the drum of the whole cast film as needed.

Next, the obtained cast film is biaxially oriented to form pores in the film. As a biaxial orientation method, the film is stretched in the longitudinal direction of the film and then stretched in the width direction, or the sequential biaxial stretching method in which the film is stretched in the width direction and then stretched in the longitudinal direction. The simultaneous biaxial stretching method can be used, but it is preferable to adopt the sequential biaxial stretching method from the viewpoint of moisture permeability, elongation, and water pressure resistance, and in particular, stretching in the longitudinal direction and then stretching in the width direction. It is preferable.

As specific stretching conditions, first, it is preferable to control the temperature at which the cast film is stretched in the longitudinal direction. As a temperature control method, a method using a temperature-controlled rotating roll, a method using a hot air oven, or the like can be adopted. The stretching temperature in the longitudinal direction is preferably 90 to 140 ° C. If the stretching temperature in the longitudinal direction is less than 90 ° C., the film may break, the elongation may decrease, or the water pressure resistance may decrease. If the stretching temperature in the longitudinal direction exceeds 140 ° C., moisture permeability may be reduced. The stretching temperature in the longitudinal direction is more preferably 110 to 135 ° C, particularly preferably 125 to 130 ° C. The stretching ratio in the longitudinal direction is preferably 3 to 7 times. If the draw ratio in the longitudinal direction is less than 3, the moisture permeability may be lowered. The higher the stretching ratio in the longitudinal direction, the better the moisture permeability. However, stretching more than 7 times may cause the film to break, the elongation to decrease, or the water pressure resistance to decrease. From the viewpoint of coexistence of moisture permeability, elongation, and water pressure resistance, the draw ratio in the longitudinal direction is more preferably 4 to 7 times. The stretching speed in the longitudinal direction at this time is preferably 200,000% / min or more, more preferably 250,000% / min or more, and further 300,000% / min or more. preferable. By increasing the stretching speed, the pore structure after biaxial stretching forms a network in the three-dimensional direction, making it easy to achieve both moisture permeability, water pressure resistance, and elongation. The upper limit of the stretching speed is 1,000,000% / min from the viewpoint of film breakage (productivity) and moisture permeability during stretching in the longitudinal direction.

Next, the end of the film is held and introduced into a tenter type stretching machine and stretched in the width direction. The stretching temperature in the width direction is preferably 130 to 155 ° C. When the stretching temperature in the width direction is less than 130 ° C., the film may break, the elongation may decrease, or the water pressure resistance may decrease. If the stretching temperature in the width direction exceeds 155 ° C., moisture permeability may decrease. The stretching temperature in the width direction is more preferably 140 to 155 ° C. from the viewpoint of achieving both moisture permeability, elongation, and water pressure resistance. The draw ratio in the width direction is preferably 4 to 15 times. If the draw ratio in the width direction is less than 4, moisture permeability may be reduced. From the viewpoints of water pressure resistance and elongation, the draw ratio in the width direction is preferably high, but if it exceeds 15 times, the film may be broken and productivity may be lowered or moisture permeability may be lowered. From the viewpoint of coexistence of moisture permeability, elongation, and water pressure resistance, the stretching ratio in the width direction is more preferably 4 to 12 times, still more preferably 6 to 12 times, and particularly preferably 8 to 11 times. The stretching speed in the width direction at this time is generally 500 to 10,000% / min. From the viewpoint of achieving both moisture permeability, water pressure resistance and elongation, 1,500 to 7,000. % / Min is preferable, and 2,000 to 5,000% / min is more preferable. In addition, the extending | stretching speed | rate of a longitudinal direction and the width direction is computable with the following formula | equation.
Stretching speed [% / min] = stretching ratio [%] / (stretching section length [m] / speed passing through stretching section [m / min])
In addition, the speed | rate which passes through the extending | stretching area of a longitudinal direction can be calculated with the following formula | equation.
Speed passing through stretching section = (Roll peripheral speed before stretching + Roll peripheral speed after stretching) / 2
Further, the speed of passing through the stretching section in the width direction is the speed of the tenter type stretching machine when passing through the stretching section in the width direction.

The “longitudinal draw ratio × width draw ratio” (a value obtained by multiplying the draw ratio in the longitudinal direction by the draw ratio in the width direction) is preferably 20 to 90 times, more preferably 30 to 90 times. .

From the viewpoint of controlling moisture permeability, elongation, and water pressure resistance, it is preferable to perform heat treatment before relaxation treatment, relaxation treatment, and heat treatment after relaxation treatment in this order in the tenter following stretching in the width direction. Here, the pre-relaxation heat treatment refers to performing heat treatment with the width after stretching in the width direction. Relaxation treatment refers to heat treatment while relaxing the film by narrowing the width of the tenter. The heat treatment after relaxation treatment refers to performing heat treatment with the width after the relaxation treatment. Further, the heat treatment step before the relaxation treatment, the relaxation treatment step, and the heat treatment step after the relaxation treatment may be collectively referred to as “heat treatment step”.

The heat treatment temperature before relaxation is preferably 140 to 170 ° C. If the heat treatment temperature before relaxation is less than 140 ° C., the elongation may be lowered or the water pressure resistance may be lowered. If the heat treatment temperature before relaxation exceeds 170 ° C., the porous film surface melts and moisture permeability decreases, or the porous film shrinks in the width direction and breaks, which may reduce productivity. is there. The heat treatment temperature before relaxation is more preferably 150 to 168 ° C. from the viewpoint of achieving both moisture permeability, elongation, and water pressure resistance.

The heat treatment time before relaxation is preferably 0.1 seconds or more and 10 seconds or less, more preferably 3 seconds or more and 8 seconds or less, from the viewpoint of achieving both elongation, water pressure resistance and productivity.

In the relaxation treatment step, the relaxation rate is preferably 5 to 35%. If the relaxation rate is less than 5%, the elongation may decrease, the water pressure resistance may decrease, or the thermal contraction rate in the width direction in the width direction may increase. If the relaxation rate exceeds 35%, the moisture permeability may decrease or the physical property unevenness may increase. From the viewpoint of coexistence of moisture permeability, elongation, and water pressure resistance, it is more preferably 5 to 15%. The relaxation rate can be calculated by [(width of porous film before relaxation−width of porous film after relaxation) / (width of porous film before relaxation)].

In the relaxation treatment step, the relaxation temperature (heat treatment temperature) is preferably 155 to 170 ° C. When the relaxation temperature is lower than 155 ° C., the contraction stress for relaxation is lowered, and the above-described high relaxation rate may not be achieved, the elongation may be decreased, and the water pressure resistance may be decreased. When the relaxation temperature exceeds 170 ° C., the polymer around the pores melts due to the high temperature, and the moisture permeability may decrease. The relaxation temperature is more preferably 160 to 168 ° C. from the viewpoints of moisture permeability, elongation, and water pressure resistance.

The relaxation rate is preferably 100 to 1,000% / min. When the relaxation rate is less than 100% / min, it is necessary to slow down the film forming rate or lengthen the tenter length, which may be inferior in productivity. When the relaxation speed exceeds 1,000% / min, the speed at which the film contracts is slower than the speed at which the rail width of the tenter shrinks, the film flutters in the tenter and tears, the unevenness in the width direction increases, It may cause deterioration of sex. The relaxation rate is more preferably 150 to 500% / min.

The heat treatment temperature after relaxation is preferably 155 to 170 ° C. When the heat treatment temperature after relaxation is less than 155 ° C., the contraction stress for relaxation becomes low, and the above-described high relaxation rate may not be achieved, the elongation may decrease, and the water pressure resistance may decrease. When the heat treatment temperature after relaxation exceeds 170 ° C., the polymer around the pores melts due to the high temperature, and the moisture permeability may decrease. The heat treatment temperature after relaxation is more preferably 160 to 168 ° C. from the viewpoints of moisture permeability, elongation, and water pressure resistance.

The heat treatment time after relaxation is preferably 0.1 second or more and 10 seconds or less, more preferably 3 seconds or more and 8 seconds or less from the viewpoint of achieving both elongation, water pressure resistance and productivity.

The film after initial stretching (the film after being stretched once each in the longitudinal direction and the width direction) may be subsequently stretched (re-stretched) again. Re-stretching may be performed either before or after the heat treatment step. When performing the heat processing mentioned later after redrawing, the heat treatment process before redrawing can be omitted. As a re-stretching method, re-stretching in the longitudinal direction or re-stretching in the width direction can be used. In addition, a method of re-stretching in the width direction after re-stretching in the longitudinal direction, a method of re-stretching in the longitudinal direction after re-stretching in the width direction, and the like can also be used. Alternatively, a simultaneous biaxial stretching method in which the longitudinal direction and the width direction of the film are stretched almost simultaneously can also be used.

As specific re-stretching conditions, first, the film after initial stretching (the film after being stretched once each in the longitudinal direction and the width direction) is controlled to a temperature at which it can be re-stretched in the longitudinal direction. As a temperature control method, a method using a temperature-controlled rotating roll, a method using a hot air oven, or the like can be adopted. The re-stretching temperature in the longitudinal direction is preferably 130 ° C. or higher, and more preferably 140 ° C. or higher, from the viewpoint of film properties and uniformity. When the re-stretching temperature in the longitudinal direction is less than 130 ° C., the stretching stress increases, so the number of film breaks may increase. If the re-stretching temperature in the longitudinal direction is too high, the polymer around the pores may melt at a high temperature and the water vapor transmission rate may be lowered, so 170 ° C. is the upper limit. The redrawing ratio in the longitudinal direction is preferably 1.02 to 2.0 times, more preferably 1.1 to 1.7 times, and still more preferably 1.1 to 1.4 times. If the redrawing ratio in the longitudinal direction is less than 1.02, the redrawing effect may not be exhibited. When the re-stretch ratio in the longitudinal direction exceeds 2.0 times, the normal temperature shrinkage in the longitudinal direction of the film increases, and when the porous film is wound as a roll, the tightening becomes stronger and the flatness is lowered. There is a case.

When re-stretching in the longitudinal direction, following re-stretching, the film may be introduced by holding the film end by a tenter-type stretching machine and re-stretching in the width direction, or in the width direction. Heat treatment may be performed by passing through a tenter type stretching machine without re-stretching.

The following conditions are preferred when re-stretching in the width direction. The re-stretching temperature in the width direction is preferably from 130 to 170 ° C., more preferably from 140 to 170 ° C., and still more preferably from 150 to 165 ° C. from the viewpoint of film characteristics and uniformity. If the re-stretching temperature in the width direction is less than 140 ° C., the stretching stress increases, so the number of film breaks may increase. If the re-stretching temperature in the width direction is higher than 170 ° C., the polymer around the pores may melt and the moisture permeability may be lowered. The redrawing ratio in the width direction is preferably 1.02 to 2.0 times, more preferably 1.05 to 1.5 times, and still more preferably 1.05 to 1.3 times. When the re-stretch ratio in the width direction is less than 1.0, it means contraction in the width direction and is not usually referred to as stretching. Moreover, when the re-stretch ratio in the width direction exceeds 2.0 times, the normal temperature shrinkage amount in the width direction of the film becomes large, and when the porous film is wound as a roll, the tightening becomes strong and the flatness is increased. May decrease.

When the heat treatment is performed without re-stretching in the width direction, or when the heat treatment is performed after re-stretching in the longitudinal direction or the width direction, the following conditions are preferable. The heat treatment temperature is preferably 145 to 175 ° C. When the heat treatment temperature is lower than 145 ° C., the elongation may decrease or the water pressure resistance may decrease. When the heat treatment temperature exceeds 175 ° C., the porous film surface melts and moisture permeability decreases, and the porous film shrinks in the width direction and breaks, which may reduce productivity. The heat treatment temperature is more preferably 155 to 170 ° C. from the viewpoint of achieving both moisture permeability, elongation, and water pressure resistance. The heat treatment time is preferably from 0.1 seconds to 10 seconds.

When re-stretching and heat treatment by a tenter-type stretching machine are not performed, a wound porous film can be obtained with a winder after re-stretching and roll heat treatment.

Since the porous film of the present invention is excellent in moisture permeability, elongation and water pressure resistance, it can be suitably used as a moisture permeable waterproof sheet, for protective clothing, packaging materials for warmers, diapers, sanitary products, adhesive bandages, oil It can also be suitably used for adsorption sheets, civil engineering and building materials, and medical applications. Moreover, the porous film of this invention and a moisture-permeable waterproof sheet using the same are excellent in the process passage property in a process. In addition, since the composite of the moisture permeable waterproof sheet and the nonwoven fabric of the present invention is excellent in low basis weight and moisture permeability, it can be suitably used as a base material for protective clothing and protective clothing. The base material and the protective clothing of the protective clothing of the present invention are not heavy when worn, and are excellent in the comfort of clothing to reduce the stuffiness in the clothing, and excellent in water pressure resistance. Therefore, the base material and protective clothing of the protective clothing of the present invention can be suitably used not only for chemical protective clothing but also for medical use.

Hereinafter, the present invention will be described in detail by way of examples. The characteristics were measured and evaluated by the following methods.

(1) β-crystal forming ability 5 mg of a porous film was sampled in an aluminum pan and measured using a differential scanning calorimeter (Seiko Denshi Kogyo RDC220). First, the temperature is raised from room temperature to 260 ° C. at 10 ° C./min (first run) in a nitrogen atmosphere, held for 10 minutes, and then cooled to 40 ° C. at 10 ° C./min. The melting peak observed when the temperature is raised again (second run) at 10 ° C / min after holding for 5 minutes is the melting peak of 145 ° C to 157 ° C. The melting of the α crystal is the melting peak of the α crystal, the melting peak of the α crystal is taken as the melting peak of the base, and the area of the region surrounded by the peak drawn from the flat portion on the high temperature side. When the heat of fusion of ΔHα and β crystals is ΔHβ, the value calculated by the following formula is β crystal forming ability. The heat of fusion was calibrated using indium.

β crystal forming ability (%) = [ΔHβ / (ΔHα + ΔHβ)] × 100
In addition, the β crystal fraction in the state of the sample can be calculated by calculating the abundance ratio of the β crystal in the same manner from the melting peak observed in the first run.

(2) Water pressure resistance Measured based on JIS L 1092: 2009 7.1.1 B method. Take a test piece of about 150mm x 150mm from the porous film or composite, attach it to the front side of the water resistance test equipment so that water hits it, put water into the cylinder, turn the piston handle and water pressure at a rate of 100 kPa per minute Was added, and the water pressure (kPa) when water came out from three places on the back side of the test piece was measured. The measurement was performed 5 times, and the average value of 5 times was taken as the water pressure resistance.

In addition, in the case where the film was broken at less than 10000 mmH ₂ O with one test piece, the measurement was performed by stacking two test pieces. However, even when two test pieces are stacked and measured, it is not necessary to divide the measured value by 2, and the obtained measured value is used as it is.

(3) Ash content after incineration (JIS L 1013)
Based on JIS L 1013: 2010 8.25, the ash content after incineration of the porous film or composite at 850 ° C. was measured.

(4) Moisture permeability The moisture permeability of the porous film or the composite was measured based on JIS L 1099: 2012 7.1 A-1 method, and evaluated in units of g / m ² · h.

(5) Melt flow rate (MFR)
It measured based on JISK7210: 1995. For the test temperature and load, refer to Annexes A and B of JIS K 7210: 1995. For example, the MFR of polypropylene resin is measured under condition M (230 ° C., 2.16 kg).

(6) Tensile elongation (6-1) Tensile elongation in the longitudinal direction of the film A porous film was cut into a rectangle having a length of 150 mm and a width of 10 mm as a sample. At this time, the length direction of the sample was the longitudinal direction of the film. Using a tensile tester (Orientec Tensilon UCT-100), the initial chuck distance was 50 mm, the tensile speed was 300 mm / min, and a tensile test was performed in the length direction of the sample. The elongation when the sample broke was measured. In addition, five samples were created, the measurement was performed 5 times, and the average value was taken as the tensile elongation in the longitudinal direction of the film.

(6-2) Tensile elongation in the width direction of the film Except that the length direction of the sample was the width direction of the film, the elongation was measured by the same method as the measurement of “tensile elongation in the longitudinal direction of the film” . In addition, five samples were created, the measurement was performed 5 times, and the average value was taken as the tensile elongation in the width direction of the film.

(7) Film thickness Using a Mitsutoyo Lightmatic VL-50A (10.5 mmφ carbide spherical surface probe, measuring load 0.06 N), the thickness of the porous film was measured at five locations, and the average value was determined for the film. It was set as the thickness.

(8) Weight per unit A porous film or composite was cut into a square of 100 mm in the longitudinal direction and 100 mm in the width direction to obtain a sample. Using an analytical electronic balance (HR-202i manufactured by A & D Co., Ltd.), the mass was measured in an atmosphere at a room temperature of 23 ° C. and a relative humidity of 65%. The measurement was performed three times, the average value was defined as the mass W of the film or composite, and the basis weight was calculated using the following equation.

Weight per unit area (g / m ² ) = W / (0.1 × 0.1).

(9) Melting point of porous film (° C)
A porous film of 5 mg was taken as a sample in an aluminum pan and measured using a differential scanning calorimeter (Seiko Denshi Kogyo RDC220). The maximum melting endothermic peak temperature when the temperature was raised from room temperature to 260 ° C. at 10 ° C./min under a nitrogen atmosphere was defined as the melting point (Tm). The measurement was performed twice for each sample, and the average value was evaluated.

(10) Process passability Thermal lamination was performed so that a polypropylene nonwoven fabric having a weight per unit area of 20 g / m ² was laminated on both surfaces of a 50 m long porous film to obtain a composite. The conditions for thermal lamination are 20% adhesion area, roll temperature: (melting point of porous film−20) ° C., and line speed: 5 m / min.

About the obtained composite_body | complex, the process passability was evaluated on the following references | standards.
Best: No wrinkles are formed in the conveyance process from unwinding to heat laminating, heat laminating, and from the heat laminating to winding, and the composite is not wrinkled.
Better: Wrinkles occur in any of the transporting process from unwinding to thermal laminating, during thermal laminating, and from thermal laminating to winding, but the composite is free from wrinkles.
Bad: Wrinkles occur in any of the unwinding to heat laminating conveyance process, the heat laminating, and the heat laminating to winding winding process, and the composite has wrinkles.

(11) Clothing comfort (wearability)
The composite obtained in (10) was cut out according to the LL size paper pattern, and the sewing part of the cut out composite was sewn with a sewing machine to obtain clothes.

In the constant temperature and humidity chamber set to 35 ° C and 50% Rh assuming the outdoor temperature in summer, the subject wore a dress made from one shirt and one work pants. The subject attached a thermo-hygrometer near the center of the chest from the top of the shirt and measured the humidity in the clothes after entering the room. This was performed on three subjects. The case where the average humidity of three people after 30 minutes was 60% Rh or less was evaluated as Good, and the case where the average humidity difference was higher than 60% Rh was evaluated as Bad.

Hereinafter, the present invention will be described more specifically based on examples. Of course, the present invention is not limited to these.

Example 1
As the polypropylene resin, 96.5 parts by mass of Homopolypropylene FLX80E4 manufactured by Sumitomo Chemical Co., Ltd., MFR = 7.5 g / 10 min, 3 parts by mass of Homopolypropylene S10CL manufactured by Prime Polymer Co., Ltd., MFR 1,000 g / 10 min, 0.3 parts by mass of N, N'-dicyclohexyl-2,6-naphthalene dicarboxyamide (manufactured by Shin Nippon Rika Co., Ltd., NU-100), which is a β crystal nucleating agent, and BASF Japan, which is an antioxidant IRGANOX 1010 and IRGAFOS 168 are each fed with raw materials from a weighing hopper to a twin screw extruder so that 0.1 parts by mass are mixed at this ratio, melt kneaded at 302 ° C., discharged from a die in a strand shape, and 25 It was solidified by cooling in a water bath at 0 ° C. and cut into chips to obtain a polypropylene composition (I).

The obtained polypropylene composition (I) is supplied to a uniaxial melt extruder, melt extruded at 220 ° C., foreign matter is removed with a 60 μm cut sintered filter, and the surface temperature is adjusted to 116 ° C. with a T-die. A cast film was obtained by discharging onto a controlled cast drum. Next, preheating was performed using a ceramic roll heated to 122 ° C., and the film was stretched 5 times in the longitudinal direction of the film at a stretching temperature of 122 ° C. and a stretching speed of 380,000% / min. Next, the end portion was introduced into a tenter type stretching machine with a clip, preheated at 150 ° C. for 3 seconds, then stretched 9.0 times at 150 ° C., and stretched in the width direction at a stretching rate of 3,300% / min.

In the subsequent heat treatment process, heat treatment was performed at 150 ° C. for 3 seconds while maintaining the distance between the clips after stretching (distance between the clips in the film width direction), and further relaxation treatment was performed at 164 ° C. with a relaxation rate of 10%. Heat treatment was performed at 164 ° C. for 5 seconds while keeping the distance. Subsequently, preheating is performed using a ceramic roll heated to 155 ° C., the film is re-stretched 1.2 times in the longitudinal direction of the film at a re-stretching temperature of 155 ° C., and then the ceramic roll heated to 150 ° C. is used. Heat treatment was performed for 5 seconds, and the porous film was wound around the core with a winder to a thickness of 500 m to obtain a porous film having a thickness of 20 μm.

(Example 2)
In the stretching process of Example 1, preheating was performed using a ceramic roll heated to 125 ° C., and the film was stretched 5 times in the longitudinal direction of the film at a stretching temperature of 125 ° C. and a stretching speed of 390,000% / min. Next, it was introduced into a tenter type stretching machine by gripping the end with a clip, preheated at 150 ° C. for 3 seconds, then stretched 9.0 times at 150 ° C., and stretched at a stretching speed of 4,000% / min. A porous film having a thickness of 20 μm was obtained under the same conditions as in 1.

Example 3
As polypropylene resin, 94.5 parts by mass of Homopolypropylene FLX80E4 manufactured by Sumitomo Chemical Co., Ltd., MFR = 7.5 g / 10 min, 5 parts by mass of Homopolypropylene S10CL manufactured by Prime Polymer Co., Ltd., MFR 1,000 g / 10 min, 0.3 parts by mass of N, N'-dicyclohexyl-2,6-naphthalene dicarboxyamide (manufactured by Shin Nippon Rika Co., Ltd., NU-100), which is a β crystal nucleating agent, and BASF Japan, which is an antioxidant IRGANOX 1010 and IRGAFOS 168 are each fed with raw materials from a weighing hopper to a twin screw extruder so that 0.1 parts by mass are mixed at this ratio, melt kneaded at 302 ° C., discharged from a die in a strand shape, and 25 It was solidified by cooling in a water bath at 0 ° C. and cut into chips to obtain a polypropylene composition (II).

A porous film having a thickness of 20 μm was obtained from the obtained polypropylene composition (II) under the same conditions as in Example 1.

Example 4
The porous film obtained in Example 1 was introduced into a tenter type stretching machine by gripping the end with a clip, preheated at 160 ° C. for 3 seconds, stretched 1.2 times in the width direction at 160 ° C., and porous with a winder The porous film was wound around the core by 500 m to obtain a porous film having a thickness of 19 μm.

(Example 5)
The porous film obtained in Example 1 was introduced into a tenter-type stretching machine by gripping the end with a clip, preheated at 160 ° C. for 3 seconds, stretched 1.2 times in the width direction at 160 ° C., and then While maintaining the distance between the clips after stretching, heat treatment was performed at 165 ° C. for 3 seconds, and the porous film was wound around the core with a winder by 500 m to obtain a porous film having a thickness of 18 μm.

(Example 6)
A cast film was obtained using the resin raw material (polypropylene composition (I) described in Example 1 under the casting conditions described in Example 1. The film was then preheated using a ceramic roll heated to 130 ° C. In the longitudinal direction, the film was stretched 4.5 times at a stretching temperature of 130 ° C. at a stretching speed of 360,000% / min. After preheating at 3 ° C. for 3 seconds, the film was stretched 5.0 times at 150 ° C. at a stretching speed of 3,600% / min.

In the subsequent heat treatment step, heat treatment was performed at 150 ° C. for 3 seconds while maintaining the distance between the clips after stretching, and further relaxation treatment was performed at 164 ° C. with a relaxation rate of 15%, and the distance between the clips after relaxation was maintained at 164 ° C. Heat treatment was performed for 5 seconds. Subsequently, preheating is performed using a ceramic roll heated to 155 ° C., and the film is re-stretched 1.1 times in the longitudinal direction of the film at a re-stretching temperature of 155 ° C., and then the ceramic roll heated to 150 ° C. is used. Heat treated for 5 seconds, introduced into a tenter-type stretching machine by gripping the end with a clip, preheated at 160 ° C for 3 seconds, stretched 1.1 times at 160 ° C, and then the distance between the clips after stretching While being maintained at 165 ° C., heat treatment was performed at 165 ° C. for 3 seconds to obtain a porous film having a thickness of 20 μm.

(Comparative Example 1)
40 parts by mass of high-density polyethylene powder (“Hi-Zex” 340M, manufactured by Mitsui Chemicals, Inc.), 30 parts by mass of polyethylene wax (“High Wax” 110P, manufactured by Mitsui Chemicals, Inc.), and calcium carbonate (trade name: A composition in which 30 parts by weight of “Star Piggot” 15A, manufactured by Shiraishi Calcium Co., Ltd., average particle size of 0.15 μm) was supplied to a twin-screw extruder, melted and mixed at 200 ° C., and then passed through the T die die. The film was extruded into a sheet shape, closely contacted on a cast drum having a surface temperature of 30 ° C., and 20 ° C. cold air was blown from the non-drum surface side to prepare a cast film. Next, the cast film was introduced into an oven heated and held at 125 ° C., preheated, stretched 3 times in the direction at a stretching rate of 30,000% / min, and cooled with a roll at 20 ° C. Subsequently, both ends of the film stretched in the longitudinal direction are guided to a tenter while being gripped by clips, and stretched 5 times in the width direction at a stretching rate of 500% / min in an atmosphere heated to 120 ° C. to obtain a porous film having a thickness of 20 μm. A polyethylene film was obtained.

(Comparative Example 2)
It was produced according to the conditions described in Example 1 of JP-A-2006-28495. As a resin composition of the polypropylene film, a polypropylene having a melting temperature of 165 ° C. (manufactured by Sumitomo Chemical Co., Ltd., WF836 DG-3, MFR: 7 g / 10 min) and 50 wt% of a polypropylene containing a β crystal nucleating agent manufactured by SUNOCO Bepol ”(type: B022-SP) 50% by weight is added and mixed, fed to a twin screw extruder, melted and mixed at 300 ° C., extruded into a gut shape, cooled through a 10 ° C. water bath, and chip cutter After cutting to 3 mm length, it was dried at 100 ° C. for 2 hours. The β crystal ratio of the β crystal nucleating agent-added polypropylene was 72%. Next, the β crystal nucleating agent-added polypropylene is supplied to an extruder heated to 300 ° C., melted, extruded into a sheet through a T die die, and placed on a cast drum heated to a surface temperature of 125 ° C. The cast film was produced by intimately adhering and blowing hot air at 120 ° C. from the non-drum surface side. Next, the cast film was introduced into an oven heated and maintained at 125 ° C., preheated, stretched 5 times in the longitudinal direction at a stretching rate of 100,000% / min, and cooled with a roll at 120 ° C. Subsequently, the film stretched in the longitudinal direction is guided to a tenter while gripping both ends with a clip, and stretched 10 times in the width direction at a stretching rate of 1,000% / min in an atmosphere heated to 130 ° C. (stretching in the longitudinal direction) (Magnification × stretch ratio in the width direction = 50 times), followed by a relaxation treatment of 3% in the width direction at 155 ° C. in a tenter to complete the crystal orientation of the microporous polypropylene film and to impart flatness and dimensional stability. And uniformly cooled and then cooled to room temperature. Thereafter, the porous film was wound around the core by 500 m with a winder to obtain a porous film having a thickness of 20 μm.

(Comparative Example 3)
As the polypropylene resin, 99.5 parts by mass of Homopolypropylene FLX80E4 manufactured by Sumitomo Chemical Co., Ltd. with MFR = 7.5 g / 10 min, N, N′-dicyclohexyl-2,6-naphthalenedicarboxamide as a β crystal nucleating agent (Nippon Rika Co., Ltd., NU-100) 0.3 parts by mass, and BASF IRGANOX 1010 and IRGAFOS 168, which are antioxidants, are mixed at a ratio of 0.1 parts by mass. The raw material is fed to the twin screw extruder, melt kneaded at 302 ° C., discharged from the die into strands, cooled and solidified in a 25 ° C. water bath, cut into chips, and the polypropylene composition (III) is obtained. Obtained.

The obtained polypropylene composition (III) is supplied to a uniaxial melt extruder, melt extruded at 220 ° C., foreign matter is removed with a 60 μm cut sintered filter, and the surface temperature is adjusted to 116 ° C. with a T-die. A cast film was obtained by discharging onto a controlled cast drum. Next, preheating was performed using a ceramic roll heated to 122 ° C., and the film was stretched 5 times in the longitudinal direction of the film at a stretching speed of 150,000% / min. Next, the end portion was introduced into a tenter type stretching machine by holding it with a clip, preheated at 155 ° C. for 3 seconds, stretched 9.0 times at 150 ° C., and stretched at a stretching rate of 3,300% / min.

In the subsequent heat treatment step, heat treatment was performed at 150 ° C. for 3 seconds while maintaining the distance between the clips after stretching, and further relaxation treatment was performed at 164 ° C. with a relaxation rate of 15%, and the distance between the clips after relaxation was maintained at 164 ° C. Heat treatment was performed for 5 seconds.

Thereafter, the porous film was wound around the core by a winder for 500 m to obtain a porous film having a thickness of 20 μm.

(Comparative Example 4)
The polypropylene composition (I) was supplied to a single screw melt extruder, melt extruded at 220 ° C., foreign matter was removed with a 60 μm cut sintered filter, and the surface temperature was controlled to 116 ° C. with a T-die. The film was discharged onto a drum to obtain a cast film. Next, preheating was performed using a ceramic roll heated to 135 ° C., and the film was stretched 4 times in the longitudinal direction of the film at a stretching speed of 450,000% / min. Next, the end portion was introduced into a tenter type stretching machine by holding it with a clip, preheated at 155 ° C. for 3 seconds, stretched 9.0 times at 155 ° C., and stretched at a stretching rate of 3,300% / min.

In the subsequent heat treatment step, heat treatment was performed at 150 ° C. for 3 seconds while maintaining the distance between the clips after stretching, and further relaxation treatment was performed at 164 ° C. with a relaxation rate of 20%, and the distance between the clips after relaxation was maintained at 164 ° C. Heat treatment was performed for 5 seconds.

Thereafter, the porous film was wound around the core by a winder for 500 m to obtain a porous film having a thickness of 20 μm.

(Comparative Example 5)
The polypropylene composition (I) was supplied to a single screw melt extruder, melt extruded at 220 ° C., foreign matter was removed with a 60 μm cut sintered filter, and the surface temperature was controlled to 116 ° C. with a T-die. The film was discharged onto a drum to obtain a cast film. Next, preheating was performed using a ceramic roll heated to 125 ° C., and the film was stretched 5 times in the longitudinal direction of the film under conditions of a stretching temperature of 125 ° C. and a stretching speed of 400,000% / min. Next, the end portion was introduced into a tenter-type stretching machine by holding it with a clip, preheated at 155 ° C. for 3 seconds, stretched 9.0 times at 155 ° C., and stretched at a stretching speed of 8,500% / min.

In the subsequent heat treatment step, heat treatment was performed at 150 ° C. for 3 seconds while maintaining the distance between the clips after stretching, and further relaxation treatment was performed at 164 ° C. with a relaxation rate of 10%, and the distance between the clips after relaxation was maintained at 164 ° C. Heat treatment was performed for 5 seconds.

Thereafter, the porous film was wound around the core by a winder for 500 m to obtain a porous film having a thickness of 20 μm.

The porous films of Examples satisfying the requirements of the present invention were excellent in moisture permeability, water pressure resistance, and elongation. In addition, the porous films of the examples were able to be suitably used as moisture permeable waterproof sheets and protective clothing with reduced ash content after incineration by reducing the stuffiness in the clothes when worn. . On the other hand, the porous film of the comparative example had insufficient moisture permeability, elongation, water pressure resistance, and ash content after incineration. Therefore, it was insufficient as a moisture-permeable waterproof sheet and protective clothing.

(Reference Example 101)
A nonwoven fabric made of polypropylene (spunbond 1) having a basis weight of 20 g / m ² , and a porous material of Example 1, using a mesh-patterned hot press roll and a receiving roll adjusted so that the handle having a surface coated with a fluororesin cannot be seen. The adhesive film was bonded in the following order.

Spunbond 1 / porous film of Example 1 / spunbond 1 in a three-layer structure, networked hot press roll temperature: (melting point of porous film−20) ° C., receiving roll temperature: (melting point of porous film -20) Bonding was performed at a temperature of 2 ° C. and a roll pressure of 2 MPa to obtain a composite having a bonding area of 10%.

The network pattern hot press roll has a mesh pattern height of 3 mm that does not touch the porous film and the spunbond of which the roll surface other than the bonded part forms a composite so as to exhibit moisture permeability even after the bonding process. A roll was used.

(Reference Example 201)
A composite having an adhesion area of 10% was obtained in the same manner as in Reference Example 101 except that the porous film obtained in Comparative Example 1 was used as the porous film.

The composite of Reference Example 101 using the porous film of Example 1 that satisfies the requirements of the present invention was excellent in moisture permeability and water pressure resistance. Further, Reference Example 101 was not heavy and had little ash after incineration. On the other hand, the composite of Reference Example 201 using the porous film of Comparative Example 1 was insufficient in moisture permeability and water pressure resistance. In addition, Reference Example 201 was heavy and a large amount of ash remained after incineration.

Claims (8)

1. The moisture permeability is 250 g / m ² · h or more, the sum of the tensile elongation in the longitudinal direction and the width direction of the film is 100 to 500%, the water pressure resistance is 4,500 mmH ₂ O or more, and the temperature is 850 ° C. A porous film having an ash content (JIS L 1013) after incineration of 0.5% by mass or less.
2. 2. The porous film according to claim 1, wherein a tensile elongation ratio of the film (longitudinal direction / width direction) is 0.6 to 1.5.
3. The porous film according to claim 1 or 2, comprising a polyolefin resin.
4. The porous film according to claim 3, wherein the polyolefin resin is polypropylene.
5. A moisture-permeable waterproof sheet using the porous film according to any one of claims 1 to 4.
6. A composite of the moisture-permeable waterproof sheet according to claim 5 and a nonwoven fabric.
7. The composite according to claim 6, wherein the basis weight is 50 g / m ² or less.
8. Protective clothing using the composite according to claim 6 or 7.