TWI795467B - Extended porous film, sanitary products and clothing - Google Patents

Abstract

An extended porous film comprising a resin composition (Z) containing a thermoplastic resin and an inorganic filler (A), and the storage elastic coefficient (E') of the resin composition (Z) calculated from the measurement of dynamic viscoelasticity and The ratio of loss elastic coefficient (E"), that is, tanδ (=E"/E') is above 0.100 at -20°C, and the porosity is 25%~80%.

Description

Extended porous film, sanitary products and clothing

The present invention relates to a stretched porous film which has excellent tactility such as softness and texture, suppresses the generation of uncomfortable sound generated when the film is rubbed, and is excellent in air permeability, moisture permeability and strength. More specifically, it relates to a sanitary product that can be suitably used for disposable diapers, sanitary products for women, etc.; clothes such as work clothes, jumpers, jackets, medical clothes, and chemical protective clothing; and masks ( A stretched porous film with excellent usability for applications requiring air permeability and moisture permeability, such as masks, covers, drapery, sheets, and wraps.

Heretofore, there is known a porous material in which a plurality of pores (microporous) are formed by stretching a resin composition containing a thermoplastic resin such as a polyolefin resin and an inorganic filler to cause interfacial delamination between the thermoplastic resin and the inorganic filler. membrane. In particular, a stretched porous film comprising a resin composition containing a polyolefin resin and an inorganic filler is used as a moisture-permeable film that suppresses liquid permeation although it has high air permeability and moisture permeability. Waterproof membrane, especially widely used in hygienic materials such as disposable diapers or women's sanitary products, work clothes, pullovers, jackets, medical clothes, chemical protective clothing and other clothes, masks, covers, curtains, sheets, scarves, etc. requiring air permeability or permeability wet use.

Most of the porous films used in these applications are directly used in applications that come into contact with human skin. Therefore, during activities in the worn state, the fact that the film has an uncomfortable sound or feel such as rustling or hard is a hindrance. The main reason for usability. Therefore, the porous film is required to have good texture or softness, good skin contact, and suppression of unpleasant sounds.

In response to these problems, for example, a method containing 50 to 300 parts by weight relative to 100 parts by weight of the total amount of 65 to 90% by weight of an ethylene/α-olefin copolymer and 35 to 10% by weight of a thermoplastic elastomer is disclosed. parts of inorganic filler (Patent Document 1); or a moisture-permeable film (Patent Document 2) containing 50 parts by weight to 400 parts by weight of an inorganic filler relative to 100 parts by weight of the following resin component (Patent Document 2). 100 parts by weight of components include 20 parts by weight to 100 parts by weight of crystalline low-density polyethylene containing 12% by weight or more of α-olefin comonomers with 4 to 8 carbon atoms and 80 parts by weight to 0 parts by weight of polyethylene .

In addition, an inorganic filler containing 50 to 300 parts by mass with respect to 100 parts by mass of a total of 30 to 70 parts by mass of a polyethylene-based resin and 70 to 30 parts by mass of an olefin-based elastomer is disclosed, respectively. , 1 mass part to 30 mass parts plasticizer breathable film (patent document 3); or containing 40 mass parts to 90 mass parts of polyethylene resin, 5 mass parts to 30 mass parts of propylene homopolymer, propylene/ 100 parts by mass of a resin component of 5 to 30 parts by mass of an ethylene copolymer elastomer, 100 to 200 parts by mass of an inorganic filler, and 1 to 20 parts by mass of a plasticizer relative to the resin component. Wet film (Patent Document 4); moisture-permeable film comprising polyethylene resin composition, inorganic filler, and styrene-based elastomer (Patent Document 5); furthermore, it is disclosed that there is a method containing 30 to 85 parts by mass of linear low-density polyethylene, 5 to 20 parts by mass of high-pressure polymerization low-density polyethylene, and metallocene ethylene/α-olefin Moisture permeability of 10 to 50 parts by mass of the resin component of the copolymer, 100 to 200 parts by mass of the inorganic filler and 1 to 20 parts by mass of the plasticizer relative to 100 parts by mass of the resin component film (Patent Document 6).

Furthermore, a film containing a thermoplastic resin and a filler of 1% to 70% by mass and having a porosity of 80% or less is disclosed (Patent Document 7); or a film containing a thermoplastic resin, an organic filler, or an inorganic filler is disclosed. A porous membrane made of a resin composition with a porosity of 10% to 80% (Patent Document 8).

[Prior art literature]

[Patent Document]

Patent Document 1: Japanese Patent Laid-Open No. 7-228719

Patent Document 2: Japanese Patent Laid-Open No. 2000-1557

Patent Document 3: Japanese Patent Laid-Open No. 2017-31292

Patent Document 4: Japanese Patent Laid-Open No. 2015-229720

Patent Document 5: International Publication No. 2014/088065

Patent Document 6: International Publication No. 2015/186808

Patent Document 7: International Publication No. 2014/156952

Patent Document 8: Japanese Patent Laid-Open No. 2006-117816

However, in Patent Document 1 and Patent Document 2, since it is an ethylene/α-olefin copolymer with a melting point of 60° C. to 100° C. or an α-olefin comonomer containing 12% by weight or more of 4 to 8 carbons, The crystalline low-density polyethylene is the main component of the film. Therefore, although it is rich in flexibility, it may melt under the high temperature conditions generated in the step of laminating other members, etc., and the dimensional stability and heat resistance will become poor. full.

In addition, in Patent Document 3 to Patent Document 6, olefin-based elastomers, propylene/ethylene copolymer elastomers, styrene-based elastomers, metallocene-based ethylene /α-olefin copolymers and other soft resins, so as to have flexibility or stretchability, thereby obtaining a film with excellent hand or touch.

On the other hand, in applications using these porous membranes, further improvement of the feeling of use is required, so further improvement of touch such as softness and touch, or suppression of the generation of uncomfortable sounds generated when the membrane is rubbed, etc. are required. . However, Patent Document 3 to Patent Document 6 do not mention technical design guidelines related to suppression of uncomfortable sounds.

In addition, Patent Document 7 describes that a filler is contained in a biodegradable resin mainly represented by a polylactic acid-based resin, and both water resistance and decomposability are tried to be achieved by setting the porosity to 80%. In the following, the water resistance of the suppression film is insufficient, but there is no mention about the control of uncomfortable sound. In addition, Patent Document 8 also describes that by setting the porosity to 10% to 80%, the decrease in moisture permeability, film strength, thermal insulation effect, and dustproof effect is suppressed, but similarly, regarding the suppression of uncomfortable sounds, Not mentioned.

The present invention has been accomplished in view of the above-mentioned problems, and aims to provide an excellent tactile feeling such as softness and hand feeling, and to suppress discomfort caused by friction of the film. A stretched porous film that produces comfortable sound and is excellent in air permeability, moisture permeability, and strength.

As a result of intensive studies, the inventors of the present invention succeeded in obtaining a stretched porous membrane capable of solving the above-mentioned problems of the prior art, and completed the present invention. That is, the object of the present invention is achieved by the following stretched porous membrane (hereinafter also referred to as "the stretched porous membrane of the present invention").

That is, the subject of the present invention can be solved by the stretched porous film (first embodiment of the present invention) comprising a resin composition (Z) containing a thermoplastic resin and an inorganic filler (A), and the resin The ratio of the storage modulus (E') to the loss modulus (E") of the composition (Z) calculated from the measurement of dynamic viscoelasticity, that is, tan δ (=E"/E') is 0.100 or more at -20°C, The porosity is 25%~80%.

Moreover, the subject of this invention can be solved by the stretched porous membrane (2nd embodiment of this invention) which contains the resin composition (Z) containing a thermoplastic resin and an inorganic filler (A), and said resin The ratio of the storage modulus (E') to the loss modulus (E") of the composition (Z) calculated from the measurement of dynamic viscoelasticity, that is, tan δ (=E"/E') is 0.100 or more at -20°C, It has a crystalline melting peak (Pm1) at 140°C~200°C.

According to the present invention, it is possible to obtain a stretched porous film that has excellent touch such as softness and texture, suppresses the occurrence of uncomfortable sounds generated when the film is rubbed, and is also excellent in air permeability, moisture permeability, and strength. , so it can be suitably used in applications requiring air permeability or moisture permeability.

Hereinafter, the stretched porous membrane of the present invention will be described as an example of an embodiment of the present invention. However, the scope of the present invention is not limited to the embodiments described below. Here, the stretched porous film refers to a porous film stretched in at least one axial direction.

Furthermore, in this specification, the so-called "main component" refers to the component that accounts for the largest mass ratio in the composition, preferably 45% by mass or more, more preferably 50% by mass or more, and still more preferably 55% by mass above. In addition, when described as "X~Y" (X, Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "more than X and less than Y", and also includes "preferably greater than X" and " It is preferably the meaning of "less than Y".

1. Extended Porous Membrane

1-1. Stretched porous membrane (first embodiment of the present invention)

The stretched porous membrane according to the first embodiment of the present invention is a stretched porous membrane comprising a resin composition (Z) containing a thermoplastic resin and an inorganic filler (A), and the resin composition (Z) is based on a dynamic viscosity The ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E") calculated from the elastic measurement, that is, tanδ (=E"/E'), is above 0.100 at -20°C, and the porosity is 25%~80%. .

The stretched porous film according to the first embodiment of the present invention preferably includes a resin composition (Z) containing 25% by mass to 54% by mass of a thermoplastic resin and 46% by mass to 75% by mass of an inorganic filler (A). Therefore, the stretched porous membrane according to the first embodiment of the present invention is more preferably a stretched porous membrane containing 25% by mass to 54 The resin composition (Z) is a thermoplastic resin of 46 mass % to 75 mass % of an inorganic filler (A) by mass %, and the storage elastic coefficient (E ') to loss elastic coefficient (E"), that is, tanδ (=E"/E') is above 0.100 at -20°C, and the porosity is 25%~80%.

What is important about the stretched porous membrane according to the first embodiment of the present invention is the storage coefficient of elasticity (E') and loss coefficient of elasticity (E") calculated from the measurement of dynamic viscoelasticity of the resin composition (Z) constituting the stretched porous membrane. The ratio of tanδ (=E"/E') at -20°C is 0.100 or higher, preferably 0.110 or higher, more preferably 0.120 or higher, and still more preferably 0.130 or higher. The upper limit of tanδ of the resin composition (Z) constituting the stretched porous membrane is not particularly limited, but is preferably 1.000 or less at -20°C from the viewpoint of heat resistance or dimensional stability. When tanδ (=E"/E') is 0.100 or more at -20°C, as described later, the sound absorption coefficient (vibration attenuation rate) for suppressing uncomfortable sounds generated when the film is rubbed can be improved, and become A film excellent in touch such as flexibility and texture.

The tanδ is preferably 0.100 or higher at -20°C to -10°C, more preferably 0.100 or higher at -20°C to 0°C, more preferably 0.100 or higher at -20°C to 10°C, and further preferably More preferably, it is at least 0.100 at -20°C to 20°C, and most preferably at least 0.100 at -30°C to 30°C. The resin composition (Z) constituting the stretched porous membrane according to the first embodiment of the present invention can widen the temperature range in which the tan δ calculated by the dynamic viscoelasticity measurement becomes 0.100 or more, and as will be described later, it is possible to suppress fluctuations in various frequencies. Comfortable sound.

Furthermore, the porosity of the stretched porous membrane according to the first embodiment of the present invention is heavy. What is needed is 25%~80%. The porosity is more preferably 30% to 80%, and more preferably 35% to 80%.

When the porosity is 25% or more, as will be described later, chances of energy loss of sound propagating in the voids of the stretched porous membrane increase, and unpleasant sound can be sufficiently suppressed. In addition, when the porosity is 80% or less, the membrane strength of a practical level can be ensured, and furthermore, the water repellency becomes sufficient, and it is difficult to cause leakage of the contact liquid.

Sound is a vibration wave in the air produced when objects move or rub against each other. When sound hits an object as incident sound, from the relationship of the law of energy conservation, the incident sound is decomposed into three sounds: the transmitted sound transmitted through the object, the reflected sound reflected by the object, and the absorbed sound absorbed by the object. . That is, when incident sound strikes an object, if the ratio of the absorbed sound absorbed by the object is large, the object is considered to have a high sound absorption coefficient.

The stretched porous membrane according to the first embodiment of the present invention is a membrane having voids connected to the inside of the resin composition (Z). That is, in the case of propagating sound in the stretched porous membrane according to the first embodiment of the present invention, it means that the sound propagated by vibrating the resin composition (Z) forming the solid part as the membrane, and the communication formed inside the membrane These two modes of propagation of sound propagate in the void. Therefore, in order to suppress the sound, it is necessary to consider suppressing the sound propagating by vibrating the resin composition (Z) and suppressing the sound propagating in the communicating voids.

In order to suppress the sound that vibrates and propagates the resin composition (Z) in the stretched porous membrane according to the first embodiment of the present invention, it is considered effective to use the sound source or Attenuation in the medium. In a resin-like viscoelastic body, the sound-absorbing effect is obtained by losing vibrational energy as heat energy. Therefore, it is considered that tan δ, which is the ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E"), is an element necessary for expressing the sound-absorbing effect. Therefore, in the first embodiment of the present invention, the extended porous The peak value of tan δ of the resin composition (Z) of the film is preferably large.

In addition, the peak position of tan δ of the resin composition (Z) constituting the stretched porous membrane according to the first embodiment of the present invention is related to the attenuation of sound at the ambient temperature where the sound is generated, and also from the viewpoint of the temperature-time conversion rule. Correlates to attenuation with respect to frequency. Therefore, in order to absorb uncomfortable sounds having various frequencies or not generate them, the peak width of tan δ is preferably wide.

Therefore, tan δ( =E"/E') of 0.100 or more at -20°C is important for suppressing the occurrence of uncomfortable sound generated when the film is rubbed. As mentioned above, it is preferable that the temperature range in which tan δ becomes 0.100 or higher can suppress uncomfortable sounds of various frequencies.

Furthermore, in the first embodiment of the present invention, it was found that not only the ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E"), that is, tan δ, but also the porosity of the porous membrane greatly contributes to the suppression of propagating Sound. By increasing the porosity, the number of collisions between the sound propagating in the air and the object increases, so it is considered that the effect of suppressing the sound propagating in the communicating voids formed inside the membrane is obtained.

Therefore, in order to increase the chance of energy loss of the sound propagating in the gap of the membrane More, it is important that the porosity of the extended porous membrane is more than 25%.

Summarizing the above, in the first embodiment of the present invention, by calculating the ratio of the storage elastic coefficient (E') and the loss elastic coefficient (E") of the resin composition (Z) calculated from the dynamic viscoelasticity measurement, tan δ, Moreover, if the porosity of the film is set in an appropriate range, not only the softness and touch such as hand feeling are excellent, but also the sound absorption coefficient (vibration attenuation rate) for suppressing uncomfortable sound generated when the film is rubbed can be improved.

In addition, the crystal fusion enthalpy (ΔHm) of the stretched porous membrane according to the first embodiment of the present invention is preferably 10 J/g to 45 J/g. In addition, the crystal melting enthalpy (ΔHm) is more preferably 12J/g-43J/g, more preferably 14J/g-41J/g, even more preferably 16J/g-39J/g. When the crystal fusion enthalpy (ΔHm) is 10 J/g or more, heat resistance and dimensional stability of the stretched porous membrane can be ensured. In addition, when the crystal melting enthalpy (ΔHm) is 45 J/g or less, it is possible to suppress the generation of uncomfortable sound described later.

As a method of suppressing the uncomfortable sound generated when the stretched porous films are rubbed against each other, it is considered effective to suppress the propagating sound and suppress the generation of the sound from the sound source. The generation of sound is the vibration of the elastic body, and as long as there is no cause of vibration (= sound source), no sound will be generated.

Focusing on the thermoplastic resin contained in the resin composition (Z) constituting the stretched porous membrane according to the first embodiment of the present invention, the thermoplastic resin is a viscoelastic body having both elastic properties and viscous properties. That is, by reducing the ratio of the elastic properties of the thermoplastic resin, when an external force is applied to make the films rub against each other, the elastic component that repels the external force and vibrates is reduced, and the generation of sound is suppressed. The index representing the ratio of the elastic property to the viscous property is the above-mentioned tan δ, but it is considered that the decrease in the macroscopic perspective and the microscopic perspective A proportion less of said elastic properties is effective for reducing unpleasant sounds. The elastic property from a macroscopic perspective refers to the storage elastic coefficient (E') calculated from the dynamic viscoelasticity measurement of the resin composition (Z) constituting the stretched porous membrane according to the first embodiment of the present invention, and the so-called microscopic perspective The elastic properties refer to the crystalline components of the resin described later.

From the viewpoint of crystallization, thermoplastic resins are classified into amorphous resins and crystalline resins. Amorphous resins are thermoplastic resins in which molecular chains cannot be folded orderly because molecular chains have a relatively bulky structure, and do not have crystalline parts. On the other hand, a crystalline resin is a thermoplastic resin in which molecular chains are folded in an orderly manner and has a high-density crystalline portion inside. Among them, even crystalline resins do not have 100% crystallized molecular chains, but have both an amorphous part in which molecular chains are randomly arranged and a crystalline part in which molecular chains are orderly folded.

The amorphous part of the crystalline resin undergoes micro-brownian motion in a temperature range above the glass transition temperature (Tg), and is in a state of high mobility. On the other hand, in the crystal part of the crystalline resin, the molecular chain is restricted as a crystal in the temperature range from the glass transition temperature (Tg) to the melting point (Tm), and becomes a part with a very high modulus of elasticity. Therefore, when the degree of crystallinity of the crystalline resin is low, there are fewer crystal parts with a high modulus of elasticity, so it is considered that there are fewer components that repel and vibrate when an external force is applied, and the generated sound is also reduced. Therefore, the crystal fusion enthalpy (ΔHm) is an indicator of the crystal component ratio in the stretched porous membrane according to the first embodiment of the present invention, and is preferably 10 J/g to 45 J/g.

The storage elastic coefficient (E') calculated by dynamic viscoelasticity measurement of the resin composition (Z) constituting the stretched porous film is preferably 8.0×10 ⁸ Pa or less at 20°C. More preferably, it is 7.0×10 ⁸ Pa or less, and still more preferably, it is 6.0×10 ⁸ Pa or less. When the storage modulus (E') at 20° C. is 8.0×10 ⁸ Pa or less, the stretched porous film has excellent texture such as texture and flexibility. In addition, the lower limit is not particularly limited, but it is preferably 1.0×10 ⁷ Pa or more at 20° C. from the viewpoint of the handling of the stretched porous membrane.

The dynamic viscoelasticity measurement of the resin composition (Z) constituting the stretched porous membrane according to the first embodiment of the present invention is to cut a strip-shaped sample piece with a width of 4 mm and a length of 35 mm at a measurement frequency of 10 Hz and a measurement strain of 0.1%, The measurement was performed while the distance between chucks was 25 mm and the temperature was raised from the measurement temperature -100° C. at a temperature increase rate of 3° C./min. At this time, the storage elastic coefficient (E'), the loss elastic coefficient (E"), and the storage elastic coefficient (E') and The ratio of loss elastic coefficient (E") is tanδ(=E"/E').

Furthermore, regarding the measurement of dynamic viscoelasticity, the thickness of the sample sheet is measured in advance, and the values of the thickness and the width of the sample sheet are input into the measuring device, thereby calculating the cross-sectional area of the sample sheet, and calculating each value.

The stretched porous membrane according to the first embodiment of the present invention has voids in the resin composition (Z), so when the porous body is directly measured, the calculated storage modulus (E') and loss modulus (E" ), and tanδ are prone to errors. Therefore, in order to obtain the storage elastic coefficient (E'), loss elastic coefficient (E"), and tanδ specified in the first embodiment of the present invention, it is preferable to use a stretched porous membrane The unstretched film of the resin composition (Z) is cut into the longitudinal direction (machine direction (machine direction) direction, MD)): 4 mm, transverse direction (transverse direction, TD): 35 mm strip-shaped sample piece for dynamic viscoelasticity measurement. However, by heating the stretched porous membrane above the melting point to melt the membrane and eliminate the voids, a press sample is produced, and a long sample piece is cut from the pressed sample to perform a dynamic viscoelasticity measurement. It is also possible to calculate the storage modulus (E'), loss modulus (E"), and tan δ specified in the first embodiment of the present invention. In the present invention, any measuring method may be employed.

Here, regarding the porosity, the stretched porous membrane was cut to a size of 50 mm in the longitudinal direction (MD) and 50 mm in the transverse direction (TD), and the specific gravity (W1) of the stretched porous membrane was measured. Next, the specific gravity (W0) of the resin composition (Z) which comprises the stretched porous membrane of 1st Embodiment of this invention was measured. In the measurement of the specific gravity (W0) of the resin composition (Z), the unstretched film of the stretched porous film according to the first embodiment of the present invention can be cut into longitudinal direction (MD): 50 mm, transverse direction (TD): 50 mm size and measure its specific gravity. In addition, when it is difficult to take an unstretched sheet, the stretched porous membrane according to the first embodiment of the present invention is heated to a temperature above the melting point to melt the stretched porous membrane and eliminate voids, and then prepare a pressed sample. The pressed sample was cut into a size of longitudinal (MD): 50 mm, transverse direction (TD): 50 mm, and specific gravity measurement was performed.

The measurement of the specific gravity (W1) of the said stretched porous membrane and the specific gravity (W0) of the said resin composition (Z) measured 3 points randomly, and used the arithmetic mean value. The porosity was calculated from the obtained specific gravity (W1) of the stretched porous film and the specific gravity (W0) of the resin composition (Z) by the following formula.

Porosity (%)=[1-(W1/W0)]×100

In addition, regarding the crystal melting enthalpy (ΔHm) of the stretched porous membrane according to the first embodiment of the present invention, the stretched porous membrane according to the first embodiment of the present invention was heated by a differential scanning calorimeter (Differential Scanning Calorimeter, DSC). After heating up from -40°C to the high temperature holding temperature at a speed of 10°C/min, keep it for 1 minute, then cool down from the high temperature holding temperature to -40°C at a cooling rate of 10°C/min, keep it for 1 minute, and then heat it at a heating rate of 10°C/min The temperature was increased from -40°C to the high-temperature holding temperature in minutes, and the crystal melting enthalpy (ΔHm) was calculated from the crystal melting peak area at this time. In this case, the high-temperature holding temperature can be arbitrarily selected within the range of Tm+20°C to Tm+150°C with respect to the crystal melting peak temperature (Tm) of the thermoplastic resin used.

Furthermore, the enthalpy of crystal fusion (ΔHm) specified in the first embodiment of the present invention is also applied in accordance with △Hm calculated from the crystal melting peak generated during the reheating process. That is, the crystallization enthalpy (ΔHc) calculated from the heat generation peak area in cold crystallization generated during the reheating process was not subtracted from ΔHm obtained during the reheating process.

Furthermore, when the stretched porous membrane according to the first embodiment of the present invention is laminated with other laminates, if the laminate is directly subjected to DSC measurement, the ΔHm derived from the stretched porous membrane may be estimated to be low. Therefore, in extension of the first embodiment of the present invention, When the stretched porous film is a laminate, the stretched porous film according to the first embodiment of the present invention can be peeled off, and ΔHm can be measured for the porous layer. When it is difficult to peel off, the ΔHm of the stretched porous membrane according to the first embodiment of the present invention of the entire laminate is calculated by DSC measurement, and the lamination ratio of the porous layer of the entire laminate is calculated by the following The calculation formula can calculate ΔHm defined in the first embodiment of the present invention. In addition, the calculation of the lamination ratio is not particularly limited, but it is preferably calculated by cross-sectional observation using an optical microscope, an electron microscope, or the like.

ΔHm (J/g) defined in the first embodiment of the present invention = ΔHm (J/g) of the stretched porous membrane of the entire laminate / layer ratio (%) of the porous layer of the entire laminate / 100 (%)

In addition, the crystal melting peak temperature (Tm) in the stretched porous film according to the first embodiment of the present invention is preferably 70°C or higher, more preferably 80°C or higher, and still more preferably 90°C or higher. In addition, there may be one crystal melting peak, or two or more peaks. When there are two or more crystal melting peaks, one of the crystal melting peak temperatures (Tm) is preferably 70° C. or higher. Furthermore, when there are two or more crystal melting peaks, the crystal melting enthalpy (ΔHm) is the total value of the crystal melting enthalpy (ΔHm) calculated from the two or more crystal melting peaks.

In addition, when the thermoplastic resin contained in the resin composition (Z) constituting the stretched porous membrane according to the first embodiment of the present invention is a polyolefin resin, the crystal melting initiation temperature is lower than the crystal melting peak temperature (Tm ) from a temperature lower than 30°C A little melting, and mostly showing broad peaks. Therefore, for Differential Scanning Calorimetry (DSC), by raising the temperature from -40°C, the baseline can be clarified and the more accurate crystal melting enthalpy (ΔHm) can be calculated.

The basis weight of the stretched porous film according to the first embodiment of the present invention is preferably 10 g/m ² to 50 g/m ² , more preferably 15 g/m ² to 40 g/m ² . When the basis weight is 10 g/m ² or more, sufficient mechanical strength such as tensile strength and tear strength can be easily ensured. In addition, since the basis weight is 50 g/m ² or less, it is easy to obtain a sufficient lightweight feeling.

Here, regarding the basis weight, the mass (g) of the sample (longitudinal (MD): 250 mm, transverse (TD): 200 mm) was measured with an electronic balance, and the value obtained by multiplying this value by 20 times was used as the basis weight.

The air permeability of the stretched porous film according to the first embodiment of the present invention is preferably 1 second/100mL to 5000 seconds/100mL, more preferably 10 seconds/100mL to 4000 seconds/100mL, and still more preferably 100 seconds/100mL to 3000 seconds/100mL. seconds/100mL. When the air permeability is 1 second/100mL or more, it is easy to sufficiently ensure water resistance and liquid permeation resistance. In addition, since the air permeability is 5000 seconds/100 mL or less, it is suggested that there are sufficient communicating pores.

Here, the air permeability is the number of seconds for 100 mL of air to pass through a sheet of paper measured according to the method stipulated in Japanese Industrial Standards (Japanese Industrial Standards, JIS) P8117:2009 (Gurley (Gurley) test machine method), for example, the air permeability can be used Measuring device (Oken type air permeability measuring machine EGO1-55 type manufactured by Asahi Seiko Co., Ltd.) was used for measurement. In the present invention, 10 points are randomly measured on the sample, and the arithmetic mean thereof is used as air permeability.

The moisture permeability in the stretched porous film according to the first embodiment of the present invention is preferably 1000g/(m ² .24h)~15000g/(m ² .24h), more preferably 1500g/(m ² .24h)~12000g/ (m ² .24h). Water resistance is suggested by the fact that the moisture permeability is 15000 g/(m ² .24h) or less. In addition, since the moisture permeability is 1000 g/(m ² .24h) or more, it is suggested that the pores have sufficient connectivity.

Here, the water vapor transmission rate is based on each condition of JIS Z0208 (water vapor transmission test method (cup method) of moisture-proof packaging materials). Use 15g of calcium chloride as a hygroscopic agent, and conduct the measurement in a constant temperature and humidity environment with a temperature of 40°C and a relative humidity of 90%. Randomly measure 2 points on the sample, and calculate the arithmetic mean value.

In the stretched porous film according to the first embodiment of the present invention, the tensile breaking strength in the stretching direction is preferably 7 N/25 mm or more, more preferably 10 N/25 mm or more. When the tensile breaking strength is 7 N/25 mm or more, practically sufficient mechanical strength and flexibility can be ensured. In addition, the upper limit is not particularly limited, but in view of elongation, it is preferably 35 N/25 mm or less. Here, with regard to the tensile breaking strength in the stretching direction, a sample cut to 100 mm in the stretching direction x 25 mm in a direction perpendicular to the stretching direction was prepared according to JIS K7127, and it was tested at a tensile speed of 23°C and a relative humidity of 50%. Tensile breaking strength when using a triple-type tensile testing machine to break under the conditions of 200m/min and a distance between chucks of 50mm. In the present invention, the arithmetic mean value of the tensile breaking strength calculated by measuring three times is used.

In the stretched porous film according to the first embodiment of the present invention, the tensile elongation at break in the stretching direction is preferably 40% to 400%, more preferably 100% to 300%. If the tensile elongation at break is 40% or more, when the stretched porous film of the present invention is used in sanitary products such as disposable diapers and sanitary products such as moisture-permeable and waterproof back sheets (back sheets), Good skin contact for excellent wearing comfort. in addition, If the tensile elongation at break is 400% or less, it has moderate rigidity and tensile strength, excellent mechanical properties, and the elongation and strain of the film during printing, slit, and coiling are small, so that the film in the production line can be obtained. Excellent mechanical adaptability.

Here, regarding the tensile elongation at break in the stretching direction, a sample cut to 100 mm in the stretching direction x 25 mm in a direction perpendicular to the stretching direction was prepared in accordance with JIS K7127, and stretched in an environment of 23° C. and a relative humidity of 50%. The tensile elongation at break when the three-connected tensile testing machine is used under the conditions of speed 200m/min and distance between chucks 50mm. In the present invention, the arithmetic mean value of the tensile elongation at break calculated by measuring three times is used.

When the stretched porous film according to the first embodiment of the present invention is heated at 60° C. for 1 hour, the heat shrinkage rate in the stretching direction is preferably less than 5.0%, more preferably less than 4.0%. When the heat shrinkage rate in the stretching direction is less than 5.0% when heated at 60° C. for 1 hour, it is preferable that there is less blocking or winding when the roll-shaped sample of the stretched porous film is stored over time. .

Here, regarding the heat shrinkage rate, a sample cut out to 200 mm in the extending direction x 10 mm in the direction perpendicular to the extending direction was left to heat for 1 hour in a convection oven set at a tank temperature of 60°C. Then, the length L (mm) in the extending direction was measured, and the value calculated by the formula "(200-L)/200×100(%)". In the present invention, the arithmetic mean value of the thermal contraction rates calculated by measuring three times is used.

The total light transmittance in the stretched porous film according to the first embodiment of the present invention is preferably 18% to 60%. Since the total light transmittance is 18% or more, when the stretched porous film according to the first embodiment of the present invention is used as a moisture-permeable and waterproof back sheet for paper diapers, etc. In the case of hygiene products such as sanitary products, it is possible to recognize even if an indicator drug that notifies that urination has been applied is applied. In addition, because the total light transmittance is less than 60%, the film is white and full of concealment.

Here, about the total light transmittance, 5 points were randomly measured using the haze meter based on JISK7361, and the arithmetic mean value was calculated|required.

Hereinafter, another embodiment of the film of the present invention will be described.

1-2. Stretched porous membrane (second embodiment of the present invention)

The stretched porous membrane according to the second embodiment of the present invention is a stretched porous membrane comprising a resin composition (Z) containing a thermoplastic resin and an inorganic filler (A), and the resin composition (Z) is based on a dynamic viscosity The ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E") calculated from the elastic measurement, ie tanδ (=E"/E'), is 0.100 or more at -20°C, and has crystallization at 140°C~200°C Melting Peak (Pm1).

The stretched porous membrane according to the second embodiment of the present invention preferably includes a resin composition (Z) containing 25% by mass to 54% by mass of a thermoplastic resin and 46% by mass to 75% by mass of an inorganic filler (A). Therefore, the stretched porous membrane according to the second embodiment of the present invention is more preferably a stretched porous membrane containing 25% by mass to 54% by mass of a thermoplastic resin and 46% by mass to 75% by mass of an inorganic filler (A) The resin composition (Z), and the ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E") calculated from the dynamic viscoelasticity measurement of the resin composition (Z) is tanδ(=E"/E ') is 0.100 or more at -20°C, and has a crystalline melting peak (Pm1) at 140°C to 200°C.

What is important about the stretched porous membrane of the second embodiment of the present invention is that it constitutes a stretched The ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E") calculated from the dynamic viscoelasticity measurement of the resin composition (Z) of the stretchable porous film, that is, tanδ (=E"/E') at -20°C The lower is 0.100 or more, preferably 0.110 or more, more preferably 0.120 or more, still more preferably 0.130 or more. In addition, the upper limit of tanδ of the resin composition (Z) constituting the stretched porous membrane is not particularly limited, but it is preferably 1.000 or less at -20°C from the viewpoint of dimensional stability. When tanδ (=E"/E') is 0.100 or more at -20°C, as described later, the sound absorption coefficient (vibration attenuation rate) for suppressing uncomfortable sounds generated when the film is rubbed can be improved, and become A film excellent in touch such as flexibility and texture.

The tanδ is preferably 0.100 or higher at -20°C to -10°C, more preferably 0.100 or higher at -20°C to 0°C, more preferably 0.100 or higher at -30°C to 0°C, and further preferably It is preferably at least 0.100 at -30°C to 10°C, more preferably at least 0.100 at -30°C to 20°C, most preferably at least 0.100 at -30°C to 30°C. The resin composition (Z) constituting the stretched porous membrane according to the second embodiment of the present invention can widen the temperature range in which the tan δ calculated by the dynamic viscoelasticity measurement becomes 0.100 or more, and as will be described later, it is possible to suppress fluctuations in various frequencies. Comfortable sound.

Furthermore, the porosity of the stretched porous membrane according to the second embodiment of the present invention is preferably 15% to 80%. The porosity is more preferably 20% to 80%, and more preferably 25% to 80%.

When the porosity is 15% or more, as will be described later, chances of energy loss of sound propagating in the voids of the stretched porous membrane increase, and unpleasant sound can be sufficiently suppressed. In addition, when the porosity is 80% or less, it is possible to secure a practically usable membrane strength, and furthermore, the water repellency becomes sufficient, and it is difficult to cause contact with liquid substances. of leaks.

Sound is a vibration wave in the air produced when objects move or rub against each other. When sound hits an object as incident sound, from the relationship of the law of energy conservation, the incident sound is decomposed into three sounds: the transmitted sound transmitted through the object, the reflected sound reflected by the object, and the absorbed sound absorbed by the object. . That is, when incident sound strikes an object, if the ratio of the absorbed sound absorbed by the object is large, the object is considered to have a high sound absorption coefficient.

The stretched porous membrane according to the second embodiment of the present invention is a membrane having voids connected to the inside of the resin composition (Z). That is, in the case of propagating sound in the stretched porous membrane according to the second embodiment of the present invention, it means that the sound propagated by vibrating the resin composition (Z) forming the solid part as the membrane, and the communication formed inside the membrane These two modes of propagation of sound propagate in the void. Therefore, in order to suppress the sound, it is necessary to consider suppressing the sound propagating by vibrating the resin composition (Z) and suppressing the sound propagating in the communicating voids.

In order to suppress the sound that vibrates and propagates the resin composition (Z) in the stretched porous membrane according to the second embodiment of the present invention, attenuation of sound in a vibration source or a medium is considered to be effective. In a resin-like viscoelastic body, the sound-absorbing effect is obtained by losing vibrational energy as heat energy. Therefore, it is considered that tan δ, which is the ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E"), is an element necessary for expressing the sound-absorbing effect. Therefore, in the second embodiment of the present invention, the extended porous The peak value of tan δ of the resin composition (Z) of the film is preferably large.

In addition, the resin composition constituting the stretched porous membrane according to the second embodiment of the present invention The peak position of tan δ of the object (Z) is related to the attenuation of the sound at the temperature of the environment in which it is generated, and is also related to the attenuation with respect to frequency from the viewpoint of the temperature-time conversion rule. Therefore, in order to absorb uncomfortable sounds having various frequencies or not generate them, the peak width of tan δ is preferably wide.

Therefore, tan δ( =E"/E') of 0.100 or more at -20°C is important for suppressing the occurrence of uncomfortable sound generated when the film is rubbed. As mentioned above, it is preferable that the temperature range in which tan δ becomes 0.100 or more widens since uncomfortable sounds of various frequencies can be suppressed.

In addition, it is considered that the porosity of the porous membrane also contributes to the suppression of transmitted sound. As the porosity increases, the number of collisions between sound propagating in the air and objects increases, so it is considered that the effect of suppressing sound propagating in the communicating voids formed inside the membrane is obtained.

Therefore, in order to increase the chance of energy loss of sound propagating through the pores of the membrane, it is preferable that the porosity of the stretched porous membrane is 15% or more.

It is important for the stretched porous membrane according to the second embodiment of the present invention to have a crystal melting peak (Pm1) at 140°C to 200°C. In addition, it is preferable to have the above crystal melting peak (Pm1) at 150°C to 190°C, more preferably to have the above crystal melting peak (Pm1) at 160°C to 180°C. Having a crystal melting peak (Pm1) at 140° C. or higher is important because sufficient heat resistance can be imparted when the stretched porous membrane is bonded to other members or laminated. In addition, by having a crystal melting temperature below 200°C The melting peak value (Pm1) is not required to extremely increase the extrusion temperature in the molding of the stretched porous film, so resin deterioration and the like are less likely to occur, and productivity is improved, so it is preferable.

In order to have the crystalline melting peak (Pm1), it can be adjusted to be at There is a crystalline melting peak (Pm1) in said range.

In addition, the stretched porous film according to the second embodiment of the present invention preferably has a crystal melting enthalpy (ΔHm1) calculated from the crystal melting peak (Pm1) of 1 J/g to 10 J/g. The crystal melting enthalpy (△Hm1) is more preferably 1J/g-8J/g, more preferably 2J/g-6J/g. When the crystal melting enthalpy (ΔHm1) is 1 J/g or more, it is preferable to have a sufficient crystal component for imparting heat resistance to the stretched porous membrane. In addition, when the crystal melting enthalpy (ΔHm1) is 10 J/g or less, it is possible to suppress the generation of uncomfortable sound described later.

By adjusting the mixing ratio of the thermoplastic resin having a melting point of 140°C to 200°C in the resin composition (Z) constituting the stretched porous membrane according to the second embodiment of the present invention, the crystal melting enthalpy (ΔHm1) can be adjusted for the stated range.

The stretched porous film according to the second embodiment of the present invention preferably has a crystal melting peak (Pm2) at 30°C to 130°C. In addition, the crystal melting enthalpy (ΔHm2) calculated from the crystal melting peak value (Pm2) is preferably 10 J/g to 45 J/g. The crystal melting enthalpy (△Hm2) is more preferably 12J/g-43J/g, more preferably 14J/g-41J/g. When the crystal melting enthalpy (ΔHm2) is 10 J/g or more, heat resistance and dimensional stability of the stretched porous membrane can be ensured. In addition, by melting the crystals The enthalpy (ΔHm2) becomes 45 J/g or less, and the generation of uncomfortable sound described later can be suppressed.

In order to have the crystalline melting peak (Pm2), the resin composition (Z) constituting the stretched porous membrane according to the second embodiment of the present invention contains a thermoplastic resin with a melting point of 30°C to 130°C and adjusts the mixing ratio. , the crystal melting peak value (Pm2) and the crystal melting enthalpy (ΔHm2) can be adjusted to the above range.

As a method of suppressing the uncomfortable sound generated when the stretched porous films are rubbed against each other, it is considered effective to suppress the propagating sound and suppress the generation of the sound from the sound source. The generation of sound is the vibration of the elastic body, and as long as there is no cause of vibration (= sound source), no sound will be generated.

Focusing on the thermoplastic resin contained in the resin composition (Z) constituting the stretched porous membrane according to the second embodiment of the present invention, the thermoplastic resin is a viscoelastic body having both elastic properties and viscous properties. That is, by reducing the ratio of the elastic properties of the thermoplastic resin, when an external force is applied to make the films rub against each other, the elastic component that repels the external force and vibrates is reduced, and the generation of sound is suppressed. An index representing the ratio of elastic properties to viscous properties is the tan δ, but it is considered that reducing the ratio of the elastic properties in terms of macroscopic and microscopic perspectives is effective for reducing uncomfortable sounds. The elastic property from a macro perspective refers to the storage elastic coefficient (E') calculated from the dynamic viscoelasticity measurement of the resin composition (Z) constituting the stretched porous membrane according to the second embodiment of the present invention. The elastic properties refer to the crystalline components of the resin described later.

First, from the viewpoint of reducing elastic properties in a macroscopic view, the storage elastic coefficient (E') calculated from the dynamic viscoelasticity measurement of the resin composition (Z) constituting the stretched porous membrane according to the second embodiment of the present invention is relatively large. Preferably, it is 8.0×10 ⁸ Pa or less at 20°C. More preferably, it is 7.0×10 ⁸ Pa or less, and still more preferably, it is 6.0×10 ⁸ Pa or less. When the storage modulus (E') is 8.0×10 ⁸ Pa or less at 20°C, the stretched porous film has excellent tactility such as hand feeling or softness, and suppresses the generation of uncomfortable sound, so it is relatively good. In addition, the lower limit is not particularly limited, but it is preferably 1.0×10 ⁷ Pa or more at 20° C. from the viewpoint of the handling of the stretched porous membrane.

The dynamic viscoelasticity measurement of the resin composition (Z) constituting the stretched porous membrane according to the second embodiment of the present invention is to cut a strip-shaped sample piece with a width of 4 mm and a length of 35 mm at a measurement frequency of 10 Hz and a measurement strain of 0.1%, The measurement was performed while the distance between chucks was 25 mm and the temperature was raised from the measurement temperature -100° C. at a temperature increase rate of 3° C./min. At this time, the storage coefficient of elasticity (E'), the loss coefficient of elasticity (E"), and the storage coefficient of elasticity (E') and loss coefficient of elasticity at each temperature were calculated from the obtained temperature-dependent profile of dynamic viscoelasticity. The ratio of (E") is tanδ(=E"/E').

Furthermore, regarding the measurement of dynamic viscoelasticity, the thickness of the sample sheet is measured in advance, and the values of the thickness and the width of the sample sheet are input into the measuring device, thereby calculating the cross-sectional area of the sample sheet, and calculating each value.

The stretched porous membrane according to the second embodiment of the present invention has voids in the resin composition (Z), so when the porous body is directly measured, the calculated storage modulus of elasticity (E'), loss modulus of elasticity (E" ), and tanδ are prone to errors. Therefore, in order to obtain the storage elastic coefficient (E'), loss elastic coefficient (E"), and tanδ specified in the second embodiment of the present invention, it is preferable to use a stretched porous membrane The unstretched film of the resin composition (Z) is cut to a length of MD: 4mm, TD: 35mm The strip-shaped sample pieces were subjected to dynamic viscoelasticity measurements. However, by heating the stretched porous membrane above the melting point to melt the membrane and eliminate the voids, a pressed sample is produced, and a long sample piece is cut from the pressed sample and measured for dynamic viscoelasticity, thereby also being able to calculate The storage coefficient of elasticity (E'), the loss coefficient of elasticity (E"), and tan δ specified in the second embodiment of the present invention. In the present invention, any measurement method may be used.

Then, as elastic properties from a microscopic perspective, the crystalline component of the resin is considered. From the viewpoint of crystallization, thermoplastic resins are classified into amorphous resins and crystalline resins. Amorphous resins are thermoplastic resins in which molecular chains cannot be folded orderly because molecular chains have a relatively bulky structure, and do not have crystalline parts. On the other hand, a crystalline resin is a thermoplastic resin in which molecular chains are folded in an orderly manner and has a high-density crystalline portion inside. Among them, even crystalline resins do not have 100% crystallized molecular chains, but have both an amorphous part in which molecular chains are randomly arranged and a crystalline part in which molecular chains are orderly folded.

The amorphous portion of the crystalline resin undergoes micro-Brownian motion in a temperature range above the glass transition temperature, and is in a state of high mobility. On the other hand, in the crystal part of the crystalline resin, the molecular chain is restricted as a crystal in the temperature range from the glass transition temperature to the melting point, and the elastic modulus is extremely high. Therefore, when the degree of crystallinity of the crystalline resin is low, there are fewer crystal parts with a high modulus of elasticity, so it is considered that there are fewer components that repel and vibrate when an external force is applied, and the generated sound is also reduced.

Therefore, the crystal melting enthalpy is an index of the crystal component ratio in the stretched porous membrane according to the second embodiment of the present invention, and the crystal melting enthalpy (ΔHm1) is preferably 1 J/g to 10 J/g. In addition, the crystal melting enthalpy (ΔHm2) is preferably 10J/g-45J/g.

Regarding the crystal melting peak value (Pm) and its peak temperature (Tm) of the stretched porous membrane according to the second embodiment of the present invention, the stretched porous membrane according to the second embodiment of the present invention was measured by using a differential scanning calorimeter (DSC). Heating rate of 10°C/min After rising from -40°C to the high temperature holding temperature, keep it for 1 minute, then cool down from the high temperature holding temperature to -40°C at a cooling rate of 10°C/min, keep it for 1 minute, and then heat it at a heating rate of 10°C /min The crystal melting peak (Pm) that occurs when the temperature is raised from -40°C to the high-temperature holding temperature, and the temperature (Tm) representing the peak.

In addition, regarding the crystal melting enthalpy (ΔHm), the crystal melting enthalpy (ΔHm) was calculated from the peak area of the above-mentioned crystal melting peak (Pm) appearing when the temperature was raised again. In this case, the high temperature holding temperature can be arbitrarily selected within the range of Tm+20°C to Tm+150°C with respect to the highest crystal melting peak temperature (Tm) of the thermoplastic resin used.

Furthermore, the crystal melting enthalpy (ΔHm) in the second embodiment of the present invention is also applied according to the reheating process even when cold crystallization occurs in the semi-crystalline resin as seen in the reheating process. △Hm calculated from the crystal melting peak generated during the heating process. That is, the crystallization enthalpy (ΔHc) calculated from the heat generation peak area in cold crystallization generated during the reheating process was not subtracted from ΔHm obtained during the reheating process.

Furthermore, when the stretched porous membrane according to the second embodiment of the present invention is laminated with other laminates, if the laminate is directly subjected to DSC measurement, the ΔHm derived from the stretched porous membrane may be estimated to be low. Therefore, in the case where the stretched porous membrane of the second embodiment of the present invention is a laminate, the The porous film was stretched and peeled off, and ΔHm was measured for the porous layer. When it is difficult to peel off, the ΔHm of the stretched porous film according to the second embodiment of the present invention of the entire laminate is calculated by DSC measurement, and the lamination ratio of the porous layer of the entire laminate is calculated by the following The calculation formula can calculate ΔHm in the second embodiment of the present invention. In addition, the calculation of the lamination ratio is not particularly limited, but it is preferably calculated by cross-sectional observation using an optical microscope, an electron microscope, or the like.

ΔHm (J/g) in the second embodiment of the present invention = ΔHm (J/g) of the stretched porous membrane in the entire laminate / layer ratio (%) of the porous layer in the entire laminate / 100 ( %)

In addition, it is important to have the crystal melting peak (Pm1) in the stretched porous membrane of the second embodiment of the present invention at 140° C. to 200° C., but it is sufficient to have at least one crystal melting peak at 140° C. to 200° C. There may be two or more. In addition, when there are two or more crystal melting peaks at 140° C. to 200° C., the crystal melting enthalpy (ΔHm1) is a total value of crystal melting enthalpy calculated from two or more crystal melting peaks.

In addition, regarding the crystal melting peak (Pm2), it is also preferable to have at least one crystal melting peak at 30° C. to 130° C., but it may be two or more. In addition, when there are two or more crystal melting peaks at 30° C. to 130° C., the crystal melting enthalpy (ΔHm 2 ) is the sum of the crystal melting enthalpy calculated from the two or more crystal melting peaks.

In addition, when the thermoplastic resin contained in the resin composition (Z) constituting the stretched porous membrane according to the second embodiment of the present invention is a polyolefin resin, the crystal melting initiation temperature is lower than the crystal melting peak temperature (Tm ) melts a little at a temperature lower than 30° C., and mostly shows a broad peak. Therefore, in differential scanning calorimetry (DSC), by raising the temperature from -40°C, the baseline can be clarified, and more accurate crystal melting enthalpy (ΔHm) can be calculated.

Summarizing the above, in the second embodiment of the present invention, by calculating the ratio of the storage elastic coefficient (E') and the loss elastic coefficient (E") of the resin composition (Z) calculated from the dynamic viscoelasticity measurement, tan δ, And the temperature at which the crystal melting peak (Pm1) occurs is set in an appropriate range, not only the softness and the touch such as hand feeling are excellent, but also the sound absorption coefficient (vibration attenuation rate) for suppressing the uncomfortable sound generated when the film is rubbed is improved. , and take into account the heat resistance required for the stretched porous membrane.

Regarding the porosity in the stretched porous membrane according to the second embodiment of the present invention, the stretched porous membrane was cut to a size of 50 mm in the longitudinal direction (MD) and 50 mm in the transverse direction (TD), and the specific gravity (W1) of the stretched porous membrane was determined. Determination. Next, the specific gravity (W0) of the resin composition (Z) which comprises the stretched porous membrane of 2nd Embodiment of this invention was measured. In the measurement of the specific gravity (W0) of the resin composition (Z), the unstretched film of the stretched porous film according to the second embodiment of the present invention can be cut into longitudinal (MD): 50 mm, transverse direction (TD): 50 mm size and measure its specific gravity. In addition, when it is difficult to take an unstretched sheet, the stretched porous membrane according to the second embodiment of the present invention is heated to a temperature above the melting point to melt the stretched porous membrane and eliminate voids, and then a pressed sample is produced. Pressed sample cut to longitudinal (MD): 50mm, Transverse direction (TD): 50mm size and specific gravity measurement.

The measurement of the specific gravity (W1) of the said stretched porous membrane and the specific gravity (W0) of the said resin composition (Z) measured 3 points randomly, and used the arithmetic mean value. The porosity was calculated from the obtained specific gravity (W1) of the stretched porous film and the specific gravity (W0) of the resin composition (Z) by the following formula.

Porosity (%)=[1-(W1/W0)]×100

The basis weight of the stretched porous film according to the second embodiment of the present invention is preferably 10 g/m ² to 50 g/m ² , more preferably 12 g/m ² to 40 g/m ² . When the basis weight is 10 g/m ² or more, sufficient mechanical strength such as tensile strength and tear strength can be easily ensured. In addition, since the basis weight is 50 g/m ² or less, it is easy to obtain a sufficient lightweight feeling.

Here, regarding the basis weight, the mass (g) of the sample (longitudinal (MD): 250 mm, transverse (TD): 200 mm) was measured with an electronic balance, and the value obtained by multiplying this value by 20 times was used as the basis weight.

The air permeability in the stretched porous film according to the second embodiment of the present invention is preferably 1 second/100mL to 5000 seconds/100mL, more preferably 10 seconds/100mL to 4000 seconds/100mL, and still more preferably 100 seconds/100mL to 3000 seconds/100mL. seconds/100mL. When the air permeability is 1 second/100mL or more, it is easy to sufficiently ensure water resistance and liquid permeation resistance. In addition, since the air permeability is 5000 seconds/100 mL or less, it is suggested that there are sufficient communicating pores.

Here, the air permeability is the number of seconds for 100 mL of air to pass through a sheet of paper measured according to the method prescribed by JIS P8117:2009 (Gurley (Gurley) testing machine method), for example It can be measured using an air permeability measuring device (Oken type air permeability measuring machine EGO1-55 manufactured by Asahi Seiko). In the present invention, 10 points are randomly measured on the sample, and the arithmetic mean thereof is used as air permeability.

The moisture permeability in the stretched porous film according to the second embodiment of the present invention is preferably 1000g/(m ² .24h) to 15000g/(m ² .24h), more preferably 1500g/(m ² .24h) to 12000g/ (m ² .24h). Water resistance is suggested by the fact that the moisture permeability is 15000 g/(m ² .24h) or less. In addition, since the moisture permeability is 1000 g/(m ² .24h) or more, it is suggested that the pores have sufficient connectivity.

Here, the water vapor transmission rate is in accordance with the conditions of JIS Z0208 (Test method for water vapor transmission rate (cup method) of moisture-proof packaging materials). Use 15g of calcium chloride as a hygroscopic agent, and conduct the measurement in a constant temperature and humidity environment with a temperature of 40°C and a relative humidity of 90%. Randomly measure 2 points on the sample, and calculate the arithmetic mean value.

In the stretched porous film according to the second embodiment of the present invention, the tensile breaking strength in the stretching direction is preferably 7 N/25 mm or more, more preferably 10 N/25 mm or more. When the tensile breaking strength is 7 N/25 mm or more, practically sufficient mechanical strength and flexibility can be ensured. In addition, the upper limit is not particularly limited, but in view of elongation, it is preferably 35 N/25 mm or less. Here, with regard to the tensile breaking strength in the stretching direction, a sample cut to 100 mm in the stretching direction x 25 mm in a direction perpendicular to the stretching direction was prepared according to JIS K7127, and it was tested at a tensile speed of 23°C and a relative humidity of 50%. Tensile breaking strength when using a triple-type tensile testing machine to break under the conditions of 200m/min and a distance between chucks of 50mm. In the present invention, the arithmetic mean value of the tensile breaking strength calculated by measuring three times is used.

In the stretched porous film according to the second embodiment of the present invention, the tensile elongation at break in the stretching direction is preferably 40% to 400%, more preferably 80% to 300%. If the tensile elongation at break is 40% or more, when the stretched porous film according to the second embodiment of the present invention is used in hygienic products such as disposable diapers and moisture-permeable waterproof back sheets such as sanitary products, etc. , good skin contact for excellent wearing comfort. In addition, if the tensile elongation at break is 400% or less, it has moderate rigidity and tensile strength, excellent mechanical properties, and small elongation and strain of the film during printing, slitting, and winding processing, thereby obtaining excellent performance in the production line. mechanical adaptability.

Here, regarding the tensile elongation at break in the stretching direction, a sample cut to 100 mm in the stretching direction x 25 mm in a direction perpendicular to the stretching direction was prepared in accordance with JIS K7127, and stretched in an environment of 23° C. and a relative humidity of 50%. The tensile elongation at break when the three-connected tensile testing machine is used under the conditions of speed 200m/min and distance between chucks 50mm. In the present invention, the arithmetic mean value of the tensile elongation at break calculated by measuring three times is used.

The total light transmittance in the stretched porous film according to the second embodiment of the present invention is preferably 18% to 60%. Since the total light transmittance is 18% or more, when the stretched porous film according to the second embodiment of the present invention is used in hygienic products such as moisture-permeable and waterproof back sheets such as disposable diapers, even if the application notice has been issued The indicator drug of urination can also be identified. In addition, because the total light transmittance is less than 60%, the film is white and full of concealment.

Here, about the total light transmittance, 5 points were randomly measured using the haze meter based on JISK7361, and the arithmetic mean value was calculated|required.

In the stretched porous membrane according to the second embodiment of the present invention, the heat resistance temperature for membrane rupture is preferably 120°C or higher, more preferably 140°C or higher, and still more preferably 160°C or higher. If the membrane rupture heat resistance temperature is 120° C. or higher, it can be judged that when the stretched porous membrane according to the second embodiment of the present invention is bonded to other members and laminated, the membrane will not be damaged due to the heat of the hot melt adhesive or the like. In case of membrane rupture, it imparts the necessary heat resistance to the extended porous membrane.

Here, regarding the heat resistance temperature of membrane rupture, the sample (100mm×100mm) was clamped between two stainless steel plates (100mm×100mm×2mm (thickness)) whose center was punched out to a circular shape of Φ50mm, and the sample (100mm×100mm) was clamped using a clip Fix the four sides, put it in a convection oven with a temperature of 120°C in the tank for 2 minutes and heat it, check whether the sample of the circular punching part of the stainless steel plate is melted or perforated, and judge the situation visually, there will be no crack or perforation For those, the heat-resistant temperature for membrane rupture is set to be above 120°C. In addition, when the temperature in the tank was changed to 140°C and 160°C, and the same evaluation was performed, those without cracks or perforations were defined as having a membrane rupture heat resistance temperature of 140°C or higher and 160°C or higher, respectively.

Hereinafter, the resin composition (Z) which comprises the stretched porous membrane of this invention is demonstrated, and the manufacturing method of the stretched porous membrane is demonstrated. In addition, the "stretched porous membrane of the present invention" refers to the "stretched porous membrane of the first embodiment of the present invention" and the "stretched porous membrane of the second embodiment of the present invention".

2. Resin composition (Z) constituting the stretched porous membrane

It is important that the stretched porous film of the present invention contains a resin composition (Z) containing 25% by mass to 54% by mass of a thermoplastic resin and 46% by mass to 75% by mass of an inorganic filler (A).

2-1. Inorganic filler (A)

Examples of the inorganic filler (A) include fine particles or minerals such as calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, titanium oxide, talc, clay, kaolinite, and montmorillonite. Calcium carbonate and barium sulfate can be suitably used in terms of the appearance of microporosity, high versatility, low price, and rich variety.

The average particle diameter of the inorganic filler (A) is preferably from 0.1 μm to 10 μm, more preferably from 0.3 μm to 5 μm, and still more preferably from 0.5 μm to 3 μm. When the average particle diameter is 0.1 μm or more, poor dispersion or secondary aggregation of the inorganic filler (A) is suppressed, and it can be uniformly dispersed in the resin composition (Z), which is preferable. On the other hand, when the average particle diameter is 10 μm or less, it is possible to suppress the generation of large pores when the membrane is thinned, and it is possible to ensure sufficient strength and water resistance for the membrane. In addition, for the purpose of improving dispersibility and mixing with resin, it is preferable to apply fatty acid, fatty acid ester, etc. to the inorganic filler in advance, and to easily fuse the surface of the inorganic filler with the resin, which is used in the present invention. Among the inorganic fillers (A), surface-treated inorganic fillers can also be used.

2-2. Thermoplastic resin

Examples of the thermoplastic resin include polyolefin resins, polystyrene resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, chlorinated polyethylene resins, polyester resins, Polycarbonate resin, polyamide resin, ethylene/vinyl alcohol copolymer, ethylene/vinyl acetate copolymer, polymethylpentene resin, polyvinyl alcohol resin, cyclic olefin resin, poly Lactic acid-based resins, polybutylene succinate-based resins, polyacrylonitrile-based resins Resin, polyethylene oxide resin, cellulose resin, polyimide resin, polyurethane resin, polyphenylene sulfide resin, polyphenylene ether resin, polyvinyl acetal resin , polybutadiene resin, polybutene resin, polyamide imide resin, polyamide bismaleimide resin, polyarylate resin, polyether imide resin, poly Ether ether ketone resins, polyether ketone resins, polyether resins, polyketone resins, polyamide resins, aramid resins, fluorine resins, polyacetal resins, etc. Among them, polyolefin-based resins are preferred as the thermoplastic resin from the viewpoints of flexibility, heat resistance, formation of communicating pores, environmental sanitation, and odor.

The thermoplastic resin may be one kind, or two or more kinds. When the said thermoplastic resin contains 2 or more types, the sum total becomes the mass of the said thermoplastic resin, and the mass ratio of the said thermoplastic resin in a resin composition (Z) is computed.

The polyolefin-based resin is a resin containing an olefin monomer as a main monomer component. The so-called main monomer component refers to the monomer component accounting for more than 50 mol% and less than 100 mol% in the resin. Examples of olefin monomers include ethylene and propylene, α-olefins such as 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene, or dienes and isoprene. Alkene, butene, butadiene, etc. may be a homopolymer of these, or may be a multi-component copolymer obtained by copolymerizing two or more kinds. In addition, vinyl acetate, (meth)acrylic acid, (meth)acrylate, glycidyl (meth)acrylate, vinyl alcohol, ethylene glycol, maleic anhydride, styrene, diene, cyclic Formed by the copolymerization of olefins. Among these, ethylene homopolymers, branched low-density polyethylenes, ethylene/α-olefin copolymers, ethylene/vinyl acetate copolymers, styrene/ethylene/propylene copolymers are preferable from the viewpoint of imparting flexibility and texture. Copolymer, Styrene/Ethylene/Butene Copolymer.

When the said thermoplastic resin is a polyolefin resin, if it is resin which has olefin monomer as a main monomer component, it may be one type, and may be two or more types. When the said polyolefin-type resin contains 2 or more types, the total becomes the mass of the said polyolefin-type resin.

In addition, when the thermoplastic resin is a polyolefin resin, it is preferable that the density of the polyolefin resin is not less than 0.850 g/cm ³ and not more than 0.940 g/cm ³ . In addition, the polyolefin-based resin preferably has a polyethylene-based resin (B) having a density of 0.910 g/cm ³ to 0.940 g/cm ³ and a density of 0.850 g/cm ³ to 0.850 g/cm 3 . A soft polyolefin-based resin (C) of 0.910 g/cm ³ .

2-2-1. Polyethylene resin (B)

The polyethylene-based resin (B) is a resin having a density of 0.910 g/cm ³ to 0.940 g/cm ³ and containing ethylene as a main monomer component. The so-called main monomer component refers to the monomer component accounting for more than 50 mol% and less than 100 mol% in the resin. Therefore, the polyethylene-based resin (B) may be an ethylene homopolymer or a copolymer containing ethylene as a main monomer component and other monomers. Examples of copolymers include ethylene/propylene copolymers, ethylene/1-butene copolymers, ethylene/1-hexene copolymers, ethylene/4-methyl-1-pentene copolymers, Ethylene/α-olefin copolymers such as ethylene/1-octene copolymers, or alternatively ethylene/vinyl acetate copolymers, ethylene/(meth)acrylic acid copolymers, ethylene/(meth)acrylate copolymers , ethylene/glycidyl (meth)acrylate, ethylene/vinyl alcohol copolymer, ethylene/ethylene glycol copolymer, ethylene/maleic anhydride copolymer, ethylene/styrene copolymer, ethylene/diene copolymer, ethylene / Cyclic olefin copolymer, etc. It may also be a multi-component copolymer containing two or more of the above-mentioned monomer components, such as an ethylene/propylene/1-butene copolymer.

Among the above, an ethylene homopolymer or an ethylene/α-olefin copolymer is preferable from the viewpoint of heat shrinkage resistance and dimensional stability.

The polyethylene-based resin (B) may be one type, or two or more types, as long as it is a resin having a density of 0.910 g/cm ³ to 0.940 g/cm ³ and containing ethylene as a main monomer component. . When the said polyethylene-type resin (B) contains 2 or more types, the total becomes the mass of the said polyethylene-type resin (B).

By containing the polyethylene-based resin (B) with a density of 0.910 g/cm ³ or more and 0.940 g/cm ³ or less, the air permeability, moisture permeability, heat shrinkage resistance, dimensional stability, and liquid leakage resistance of the stretched porous film can be satisfied. Sex, concealment, appearance, etc. The density of the polyethylene-based resin (B) is more preferably from 0.910 g/cm ³ to 0.937 g/cm ³ , particularly preferably from 0.910 g/cm ³ to 0.935 g/cm ³ . Here, the density is a density measured by a pycnometer method (JIS K7112 B method). In addition, it is the value at the time of measuring similarly about the density of the resin mentioned later.

The polyethylene-based resin (B) may be linear or branched. The production method of the polyethylene-based resin (B) is not particularly limited, and a known polymerization method using a known catalyst for olefin polymerization is used, for example, a Ziegler-Natta type catalyst is used as a representative The multi-site (multi-site) catalyst, or the polymerization method of the single-site catalyst represented by the metallocene catalyst, etc.

Preferably, at least one of the polyethylene-based resins (B) is branched low-density polyethylene. When at least one of the polyethylene-based resins (B) is branched low-density polyethylene, the melt tension of the resin composition (Z) is increased, and the moldability is improved, Therefore better. In addition, the value of tanδ (=E"/E'), which is the ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E") calculated from the dynamic viscoelasticity measurement of the branched low-density polyethylene, is at 0°C~ Since it shows a large value at 30 degreeC, it is preferable that at least 1 type of said polyethylene-type resin (B) is a branched low-density polyethylene.

The melting point of the polyethylene-based resin (B) is preferably 110°C to 135°C, more preferably 110°C to 130°C. When the melting point of the polyethylene-based resin (B) is 110° C. to 135° C., it is preferable because heat shrinkage resistance and dimensional stability of the stretched porous film can be improved.

Here, the melting point is determined by heating about 10 mg of resin from -40°C to 200°C at a heating rate of 10°C/min using a differential scanning calorimeter (DSC), keeping it at 200°C for 1 minute, and then cooling at a rate of 10°C. The crystal melting peak temperature (Tm) (°C) was obtained from the measured thermogram (thermogram) when the temperature was lowered to -40°C at a heating rate of 10°C/min and then raised to 200°C at a heating rate of 10°C/min. In addition, it is the value at the time of measuring similarly about the melting point of the resin mentioned later.

The melt flow rate (MFR) of the polyethylene-based resin (B) is preferably 0.1 g/10 minutes to 20 g/10 minutes, more preferably 0.5 g/10 minutes to 10 g/10 minutes. By making MFR 0.1 g/10 minutes or more, since the formability of a stretched porous film can fully be maintained, it is preferable. Moreover, since the intensity|strength of a stretched porous membrane can fully be maintained by making MFR into 20 g/10 minutes or less, it is preferable.

Here, MFR is a value measured in accordance with JIS K7219, and the measurement conditions are 190° C. and a 2.16 kg load.

2-2-2. Soft polyolefin resin (C)

The soft polyolefin-based resin (C) is a resin having a density of 0.850 g/cm ³ to less than 0.910 g/cm ³ and containing olefin monomers as main monomer components. The so-called main monomer component refers to the monomer component accounting for more than 50 mol% and less than 100 mol% in the resin. Examples of olefin monomers include ethylene and propylene, α-olefins such as 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene, or dienes and isoprene. Alkene, butene, butadiene, etc. may be a homopolymer of these, or may be a multi-component copolymer obtained by copolymerizing two or more kinds. In addition, vinyl acetate, (meth)acrylic acid, (meth)acrylate, glycidyl (meth)acrylate, vinyl alcohol, ethylene glycol, maleic anhydride, styrene, diene, cyclic Formed by the copolymerization of olefins. Among these, ethylene homopolymers, branched low-density polyethylenes, ethylene/α-olefin copolymers, ethylene/vinyl acetate copolymers, styrene/ethylene/propylene copolymers are preferable from the viewpoint of imparting flexibility and texture. Copolymer, Styrene/Ethylene/Butene Copolymer.

The soft polyolefin-based resin (C) may be one type of resin having a density of 0.850 g/cm ³ to less than 0.910 g/cm ³ and containing olefin monomers as the main monomer component, or may be For two or more. When the said soft polyolefin-type resin (C) contains 2 or more types, the total becomes the mass of the said soft polyolefin-type resin (C). By including the soft polyolefin-based resin (C) with a density of 0.850 g/cm ³ to less than 0.910 g/cm ³ , the flexibility and texture of the stretched porous film can be improved, and the satisfaction of the texture can be improved. In addition, the density of the soft polyolefin resin (C) is preferably from 0.855 g/cm ³ to less than 0.910 g/cm ³ , more preferably from 0.860 g/cm ³ to less than 0.910 g/cm ³ .

The melt flow rate (MFR) of the soft polyolefin resin (C) Preferably it is 0.1g/10 minutes to 20g/10 minutes, more preferably 0.5g/10 minutes to 10g/10 minutes. By making MFR 0.1 g/10 minutes or more, since the formability of a stretched porous film can fully be maintained, it is preferable. Moreover, since the intensity|strength of a stretched porous membrane can fully be maintained by making MFR into 20 g/10 minutes or less, it is preferable.

In addition, the peak value of tan δ (=E"/E') which is the ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E") calculated by the dynamic viscoelasticity measurement of the soft polyolefin resin (C) It is preferably in the range of -50°C to 50°C. When the peak value of tanδ of the soft polyolefin-based resin (C) is in the range of -50°C to 50°C, it is preferable because it contributes to suppression of uncomfortable sounds such as rustling.

In addition, the peak value of tan δ (=E"/E') which is the ratio of the storage elastic coefficient (E') to the loss elastic coefficient (E") calculated by the dynamic viscoelasticity measurement of the soft polyolefin resin (C) Preferably, it is 0.100 or more, More preferably, it is 0.200 or more, More preferably, it is 0.300 or more. When the peak value of tanδ of the soft polyolefin-based resin (C) is 0.100 or more, it is preferable because it contributes to suppression of uncomfortable sounds such as rustling.

The thermoplastic resin is a polyolefin-based resin, and the polyolefin-based resin has a polyethylene-based resin (B) with a density of 0.910 g/cm ³ or more and 0.940 g/cm ³ or less, and a density of 0.850 g/cm 3 or less. ³ or more and less than 0.910 g/cm ³ of the soft polyolefin-based resin (C), the inorganic filler (A), the polyethylene-based resin (B), and the soft polyolefin-based resin The mixing composition of (C) is preferably (A)/(B)/(C)=50% by mass to 75% by mass/1% by mass to 45% by mass/1% by mass to 45% by mass (wherein (A) ) and (B) and (C) the total mass % is set to 100 mass %.), more preferably (A) / (B) / (C) = 50 mass % ~ 70 mass % / 3 mass % ~ 43 mass %/3 mass %~43 mass %.

In the mixing composition ratio of the inorganic filler (A) to the polyethylene resin (B) to the soft polyolefin resin (C), the mixing composition ratio of the inorganic filler (A) is When it is more than the lower limit within the above-mentioned preferred range, the formation of pores accompanying stretching becomes sufficient, and communicating pores are easily formed, and sufficient air-permeable characteristics or moisture-permeable characteristics are easily exhibited.

Moreover, when the mixing composition ratio of the said inorganic filler (A) is below the upper limit in the said preferable range, molding of a resin composition becomes easy, and there exists no problem of productivity.

In addition, when the mixing composition ratio of the polyethylene-based resin (B) is not less than the lower limit within the above-mentioned preferable range, and the mixing composition ratio of the soft polyolefin-based resin (C) is within the above-mentioned preferable range, When below the upper limit, it becomes a film excellent in heat shrinkage resistance or dimensional stability.

Furthermore, when the mixing composition ratio of the polyethylene-based resin (B) is not more than the upper limit within the above-mentioned preferable range, and the mixing composition ratio of the soft polyolefin-based resin (C) is within the above-mentioned preferable range, In the case of more than the lower limit, good touch such as softness and touch can be obtained by skin contact, and it is easy to suppress uncomfortable sound generated when the film is rubbed.

On the other hand, the polyolefin-based resin includes polyethylene-based resin (B) having a density of 0.910 g/cm ³ to 0.940 g/cm ³ , and a density of 0.850 g/cm ³ to less than 0.910 g/cm 3 . In addition to the soft polyolefin-based resin (C) of g/cm ³ , a polypropylene-based resin (D) described later may be included.

<Polypropylene-based resin (D)>

The density of the polypropylene-based resin (D) is preferably from 0.890 g/cm ³ to less than 0.910 g/cm ³ . In addition, the melting point is preferably 140°C to 170°C. In addition, MFR is preferably 10g/10min~50g/10min. Here, MFR of a polypropylene resin (D) is the value measured based on the condition M of JISK7210, and the said measurement conditions are 230 degreeC and 2.16 kg load.

The thermoplastic resin is a polyolefin-based resin, and the polyolefin-based resin has a polyethylene-based resin (B) with a density of 0.910 g/cm ³ or more and 0.940 g/cm ³ or less, and a density of 0.850 g/cm ^{3 or less} . In the case of the soft polyolefin-based resin (C) or the polypropylene-based resin (D) of 0.910 g/cm or more and less than 0.910 g/cm ³ , the polyethylene-based resin (B) and the soft polyolefin-based resin (C) , The mixing composition of the polypropylene-based resin (D) is preferably (B)/(C)/(D)=1% by mass to 25% by mass/50% by mass to 98% by mass/1% by mass to 25% by mass % (wherein, the total mass % of (B) and (C) and (D) is set as 100 mass %.), more preferably (B) / (C) / (D) = 5 mass % ~ 20 mass % /60% by mass to 90% by mass/5% by mass to 20% by mass (here, the total mass % of (B), (C) and (D) is set to 100% by mass.).

In the mixing composition ratio of the polyethylene-based resin (B) to the soft polyolefin-based resin (C) to the polypropylene-based resin (D), the mixing composition ratio of the polypropylene-based resin (D) When it is more than the lower limit in the said preferable range, a stretched porous membrane will express sufficient heat resistance easily.

In addition, the mixing composition ratio of the polyethylene-based resin (B) is the preferred When it is more than the lower limit in the range, molding of the resin composition becomes easy, and there is no problem in productivity.

Furthermore, when the mixing composition ratio of the polypropylene-based resin (D) is not more than the upper limit of the above-mentioned preferable range, and the mixing composition ratio of the polyethylene-based resin (B) is at the upper limit of the above-mentioned preferable range, When the mixing composition ratio of the soft polyolefin-based resin (C) is equal to or greater than the lower limit within the above-mentioned preferred range, a good touch such as softness or touch can be obtained in contact with the skin, and it is easy to suppress Uncomfortable sound produced when the film is rubbed against.

2-3. Other ingredients

Furthermore, the stretched porous film of the present invention preferably contains 0.1% by mass to 8.0% by mass of the plasticizer (E) in the resin composition (Z). When the plasticizer (E) is contained in an amount of 0.1% by mass or more, the value of tan δ of the resin composition (Z) increases, and furthermore, the peak width of tan δ of the resin composition (Z) can be broadened. In addition, the crystal melting enthalpy (ΔHm) of the stretched porous membrane can be reduced. On the other hand, if the plasticizer (E) is 8.0% by mass or less, bleeding of the plasticizer can be suppressed, and blocking when the stretched porous membrane is wound up into a roll or printing defects during printing can be suppressed.

Examples of the plasticizer (E) include the following ester-based plasticizers. Ester plasticizers with polar structures can be used, such as monovalent carboxylate plasticizers (such as butyric acid, isobutyric acid, hexanoic acid, 2-ethylhexanoic acid, heptanoic acid, caprylic acid, lauryl A compound obtained by condensation reaction of a monocarboxylic acid such as monocarboxylic acid, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, etc., with a polyhydric alcohol. If specific compounds are exemplified, Triethylene glycol di-2-ethylhexanoate, triethylene glycol diisobutyrate, triethylene glycol Diol-caproate, Triethylene glycol di-2-ethylbutyrate, Triethylene glycol dilaurate, Ethylene glycol di-2-ethylhexanoate, Diethylene glycol di-2-ethyl Hexanoate, Tetraethylene Glycol Di-2-Ethylhexanoate, Tetraethylene Glycol Diheptanoate, PEG#400 Di-2-Ethylhexanoate, Triethylene Glycol Mono-2-Ethylhexanoate , glycerol tri-2-ethylhexanoate, pentaerythritol tetrastearate, dipentaerythritol hexacaprylate, diglycerol tetrastearate, diglycerol distearate, etc.), polycarboxylate plasticizers Agents (such as adipic acid, succinic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid and other polycarboxylic acids, methanol, ethanol, butyl Alcohol, hexanol, 2-ethylbutanol, heptanol, octanol, 2-ethylhexanol, decanol, dodecanol, butoxyethanol, butoxyethoxyethanol, benzyl alcohol and other carbon The compound obtained by the condensation reaction of the monohydric alcohol of the number 1 to 12. If the specific compound is exemplified, it is dihexyl adipate, di-2-ethylhexyl adipate, diheptyl adipate, dihexyl adipate, Dioctyl adipate, di-2-ethylhexyl adipate, bis(butoxyethyl adipate), bis(butoxyethoxyethyl adipate), adipate mono(2- ethylhexyl), dibutyl phthalate, dihexyl phthalate, bis(2-ethylbutyl phthalate), dioctyl phthalate, di( 2-ethylhexyl), benzylbutyl phthalate, didodecyl phthalate, trioctyl trimellitate, etc.), hydroxycarboxylate plasticizers (hydroxycarboxylate Monohydric alcohol esters of acids; methyl ricinoleate, ethyl ricinoleate, butyl ricinoleate, methyl 6-hydroxycaproate, ethyl 6-hydroxycaproate, butyl 6-hydroxycaproate, hydroxycarboxylate Polyol esters of acids; ethylene glycol bis(6-hydroxyhexanoate), diethylene glycol bis(6-hydroxyhexanoate), triethylene glycol bis(6-hydroxyhexanoate), 3-methyl 1,5-pentanediol di(6-hydroxyhexanoate) ester, 3-methyl-1,5-pentanediol di(2-hydroxybutyrate) ester, 3-methyl-1,5- Pentylene Glycol Bis(3-Hydroxybutyrate), 3-Methyl -1,5-pentanediol bis(4-hydroxybutyrate) ester, triethylene glycol bis(2-hydroxybutyrate) ester, glycerol tri(ricinoleic acid) ester, L-tartrate bis(1-(2 - ethylhexyl ester)), castor oil, etc.), polyester-based plasticizers and other suitable plasticizers.

Examples of castor oils include ordinary castor oil, purified castor oil, hardened castor oil, and dehydrated castor oil. Moreover, as hardened castor oil, the hardened castor oil etc. which have triglyceride containing 12-hydroxystearic acid and glycerin as a main component are mentioned.

In addition to the above-mentioned raw materials, other resin raw materials, or recycled resins, compatibilizers, processing aids, melt viscosity modifiers, etc. , Antioxidant, antiaging agent, heat stabilizer, light stabilizer, weather resistance stabilizer, ultraviolet absorber, neutralizing agent, nucleating agent, crosslinking agent, lubricating material, anticaking agent, slip agent, anti Fog agents, antibacterial agents, deodorants, flame retardants, antistatic agents, colorants, pigments, and the like are appropriately added to the resin composition (Z) constituting the stretched porous membrane of the present invention.

3. Fabrication method of stretched porous membrane

The method for producing the stretched porous membrane of the present invention is not particularly limited, and it can be produced by a previously known method, but it is important to stretch at least in a uniaxial direction.

Here, the term "film" has a meaning ranging from a thick sheet to a thin film. The film may be in either a flat shape or a tubular shape, but is preferably flat in terms of productivity (several products can be obtained in the width direction of the raw material sheet) or printing on the inner surface. shape. As a method for producing a planar film, for example, the following method can be exemplified: using an extruder, the resin composition is melted and extruded into a film form from a die, and cooled by a cooling roll, air cooling, or water cooling. After curing, the obtained film (unstretched film) was stretched at least in the uniaxial direction, and then wound up with a winder to obtain a film.

Moreover, as a method of obtaining the said unstretched membrane, it is preferable to melt-knead after mixing the composition (Z) which comprises the stretched porous membrane of this invention. Specifically, mixing with a tumbler mixer, a mixing roll, a Banbury mixer, a ribbon blender, a super mixer, etc. After mixing for an appropriate time, extruders such as counter-rotating twin-screw extruders and co-rotating twin-screw extruders are used to promote uniform dispersion and distribution of the composition. A die such as a T-die or a circular die may be connected to the front end of the extruder, and the obtained resin composition may be formed into a film. In addition, it is also possible to connect a strand die to the front end of the kneader, and after temporarily pelletizing (pelletizing) by means of strand cutting (strand cutting), die cutting (die cutting), etc., the obtained The pellets (with optional additional components) are introduced into a single-screw extruder, etc., and a die such as a T-shaped die or a circular die is connected to the front end of the extruder to form a film. When forming into a film shape, film forming methods such as inflation forming, tube forming, and T-die forming are preferable. The extrusion temperature is preferably around 180°C to 260°C, more preferably 190°C to 250°C. Controlling the dispersion state of the material by optimizing the extrusion temperature or the state of shear is also effective for setting various physical properties and mechanical properties of the film described below to desired values.

The stretched porous film of the present invention can be produced by stretching the unstretched film. For example, use an extruder to melt the resin and extrude it from a T-die or a circular die, cool and solidify it with a cooling roll, and pass it in the longitudinal direction (flow direction of the film, MD) roll stretching, or tenter stretching in the transverse direction (direction perpendicular to the flow direction of the film, MD), or the like so as to extend at least in the uniaxial direction. In addition, after extending in the vertical direction, it may extend in the horizontal direction, or may extend in the vertical direction after extending in the horizontal direction. In addition, it may extend two or more times in the same direction. Furthermore, after extending|stretching in the longitudinal direction, it may extend in the lateral direction, and may also extend in the longitudinal direction. In addition, it can also be stretched in the vertical and horizontal directions simultaneously by a simultaneous biaxial stretching machine. In addition, a tubular unstretched film can also be stretched radially by internal pressure by tubular forming. Furthermore, after stretching the folded state of the tubular unstretched film obtained by inflation molding, the edges of the folded tubular stretched porous film may be cut, divided into two pieces and wound up separately, or The edge of the folded unstretched film is cut and divided into two unstretched films, stretched separately, and wound up separately.

In the present invention, stretching is preferably performed at least once in the longitudinal direction, and stretching in the longitudinal direction may be performed twice in consideration of uneven stretching and air permeability. The stretching temperature is preferably from 0°C to 90°C, more preferably from 20°C to 70°C. In addition, the elongation ratio is preferably 1.5 times to 6.0 times in total, and more preferably 2.0 times to 5.0 times. By setting the stretching ratio to 1.5 times or more in total, it is uniformly stretched, and a stretched porous film having an excellent appearance is obtained. On the other hand, the cracking of a film can be suppressed by making stretching ratio into 6.0 times or less in total.

If necessary, heat treatment or relaxation treatment may be performed at a temperature of 50° C. to 120° C. after stretching for the purpose of reducing the thermal shrinkage rate or improving various physical properties. In the case of stretching by roll stretching, heat treatment can be performed by bringing the stretched film into contact with a heated roll (annealing roll) between the stretching step and the winding step. reason. In addition, while heating by the annealing roll, the speed of the next contacting roll is made slower than the speed of the annealing roll, thereby enabling relaxation treatment. In addition, these heat treatments and relaxation treatments can also be performed in another step after stretching the unstretched film and winding up the stretched porous film. If the temperature of the heat treatment or relaxation treatment is too low, it may be difficult to reduce the shrinkage rate of the film, and if the temperature is too high, it may be wound around a roll or the formed micropores may be blocked. Therefore, it is preferable to perform heat treatment or relaxation treatment at a temperature of 50° C. or higher and 120° C. or lower. These heat treatments and relaxation treatments may be divided into multiple times and implemented.

In addition, the stretched porous film of the present invention may be subjected to surface treatment or surface processing such as slits, corona treatment, printing, application of an adhesive, coating, and vapor deposition as necessary.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In addition, the measured value and evaluation shown in an Example were performed as follows. In the examples, the flow direction of the film is described as the "longitudinal" direction (or MD), and its perpendicular direction is described as the "transverse" direction (or TD).

(1) Measurement of dynamic viscoelasticity of the resin composition (Z) constituting the stretched porous membrane

In the examples and comparative examples shown below, a strip-shaped sample sheet cut into MD: 4 mm and TD: 35 mm using an unstretched film of the resin composition (Z) constituting the stretched porous film was used, Carry out dynamic viscoelasticity measurement according to the method described, calculate storage elastic coefficient (E'), loss elastic coefficient (E"), and the ratio of storage elastic coefficient (E') and loss elastic coefficient (E") that is tanδ (=E "/E'). Then, at -20℃ The case where tan δ was 0.100 or more was judged as "A", and the case where tan δ was less than 0.100 at -20°C was judged as "B".

Furthermore, the values of E' (unit: ×10 ⁸ Pa) at 20°C and tanδ at -30°C, -20°C, -10°C, 0°C, 10°C, 20°C, and 30°C are summarized in Table 1~Table 3.

(2) Basis weight of extended porous membrane

The basis weight of the stretched porous membrane was calculated according to the method described above.

(3) Porosity of extended porous membrane

The porosity of the stretched porous membrane was calculated according to the method described above.

(4) The air permeability of the extended porous membrane

The air permeability of the stretched porous membrane was calculated according to the method described above. As an air permeability measuring device, Oken type air permeability measuring machine EGO1-55 manufactured by Asahi Seiko Co., Ltd. was used.

(5) Moisture permeability of extended porous membrane

The water vapor transmission rate of the stretched porous membrane was calculated according to the method described above.

(6) Tensile breaking strength in the extending direction of the stretched porous membrane

The tensile breaking strength of the stretched porous membrane in the stretching direction (MD in this example and the comparative example) was calculated according to the method described above.

(7) Tensile elongation at break in the extending direction of the stretched porous film

The tensile elongation at break in the stretching direction (MD in this example and the comparative example) of the stretched porous film was calculated according to the method described above.

(8) Heat shrinkage rate of stretched porous membrane

In embodiment 101～embodiment 104 and comparative example 101～comparative example 102, press The heat shrinkage rate in the stretching direction (MD in this example and the comparative example) of the stretched porous film when heated at 60° C. for 1 hour was calculated according to the method described above.

(9) The total light transmittance of the extended porous membrane

The total light transmittance of the stretched porous film was calculated according to the method described above.

(10) Crystal melting peak value (Pm) and crystal melting enthalpy (△Hm) of extended porous membrane

Using a differential scanning calorimeter (DSC), the stretched porous membranes obtained in Examples and Comparative Examples shown below were heated from -40°C to 200°C at a heating rate of 10°C/min, held for 1 minute, and then cooled. After cooling down from 200°C to -40°C at a speed of 10°C/min, keep it for 1 minute, and then raise the temperature from -40°C to 200°C at a heating rate of 10°C/min. Pm), and the peak area of the crystal melting peak (Pm) in the reheating process to calculate the crystal melting enthalpy (ΔHm) of the stretched porous membrane.

In Example 201-Example 205 and Comparative Example 201-Comparative Example 204, the presence or absence of a crystal melting peak (Pm1) was confirmed at 140° C. to 200° C. at this time. In addition, the peak temperature (Tm1) and crystal melting enthalpy (ΔHm1) were calculated from the above (Pm1). Similarly, the presence or absence of a crystal melting peak (Pm2) was confirmed at 30°C to 130°C. In addition, the peak temperature (Tm2) and crystal melting enthalpy (ΔHm2) were calculated from the above (Pm2).

(11) Flexibility of stretched porous membrane

The stretched porous membranes obtained in Examples and Comparative Examples shown below were cut to 1000 mm in the longitudinal direction (MD) and 200 mm in the transverse direction (TD), and were touched by hand, according to The following judgment criteria were used for evaluation.

A: A soft texture is felt in the film.

B: Hardness is felt in the film.

(12) Unpleasant sound of extended porous membrane

The uncomfortable sound of the stretched porous film was evaluated by the following test or uncomfortable sound measurement.

(12-1) Uncomfortable sound caused by friction of extended porous membrane

The stretched porous membranes obtained in Examples and Comparative Examples shown below were cut into 1000 mm in the longitudinal direction (MD) and 200 mm in the transverse direction (TD), and the films were rubbed against each other, and evaluated according to the following criteria.

A: Even if they rub against each other, there is no uncomfortable sound.

B: When they rub against each other, an uncomfortable sound of rustling is felt.

(12-2) Measurement of uncomfortable sounds of stretched porous membranes

Regarding the measurement of uncomfortable sounds of stretched porous membranes, the measurement site is in a single room with a width of about 3m, a length of about 4m, and a height of about 3m (in an environment with little influence of external noise), using Rion Co., Ltd. The common noise meter NL-42 is performed by setting the frequency weighting characteristic as A characteristic and setting the time weighting characteristic as F characteristic.

First, the stretched porous membranes obtained in Examples and Comparative Examples shown below were cut out to 400 mm in the longitudinal direction (MD) and 200 mm in the transverse direction (TD), and were folded once at the center in the longitudinal direction so that they were folded in half. Then, clamp the TD both ends of the superimposed stretched porous membrane so that the distance between the clamped TD both ends becomes 100 mm. way to adjust.

Furthermore, after adjusting the distance between the clamped stretched porous membrane and the microphone (sound collecting part) of the ordinary noise meter to 100mm, The clamped end was vibrated back and forth 3 times within 1 second to rub the films against each other, and the time-average sound level (LAeq) within 10 seconds of the measurement time was measured and evaluated according to the following criteria.

In addition, the time average sound level (sound level) (LAeq) of 10 seconds of measurement time in the state which did not vibrate a membrane (non-operation state) was 26 dB.

A: The time average sound level (LAeq) is above 26dB and less than 35dB

B: The time average sound level (LAeq) is above 35dB and less than 45dB

C: The time average sound level (LAeq) is above 45dB

(13) Membrane break heat resistance temperature of stretched porous membrane

In Example 201-Example 205 and Comparative Example 201-Comparative Example 204, the membrane rupture heat resistance temperature was further evaluated according to the method described above. Regarding the evaluation, the temperature in the tank of the convection oven was set to 120° C., 140° C., and 160° C., and the state after being left still in the tank for 2 minutes and heated was evaluated by visual evaluation according to the following criteria.

A: There were no cracks or perforations in the sample of the round punched portion of the stainless steel plate.

B: The sample of the round punched part of the stainless steel plate is melted and perforated.

(14) Comprehensive evaluation

(14-1) Example 101~Example 104 and Comparative Example 101~Comparative Example 102

In consideration of the evaluations shown in (1) to (12) above, a comprehensive evaluation was performed based on the following criteria.

A: It is a film suitable for applications requiring air permeability or moisture permeability, which has excellent touch such as softness and touch, and suppresses the generation of uncomfortable sounds generated when the film is rubbed.

B: It is a film that has excellent touch such as flexibility and texture, and is excellent in air permeability and moisture permeability, but it is a film in which the generation of uncomfortable sound is felt.

C: It is a film excellent in air permeability and moisture permeability, but it is a film in which the tactile sensation such as softness and texture is not felt, and the generation of uncomfortable sound is felt.

D: A film with insufficient physical properties required for stretched porous films such as air permeability and moisture permeability.

(14-2) Example 105~Example 108 and Comparative Example 103~Comparative Example 104

In consideration of the evaluations shown in (1) to (7) and (9) to (12) above, comprehensive evaluation was performed according to the following criteria.

A: It is a film suitable for applications requiring air permeability or moisture permeability, which has excellent touch such as softness and touch, and suppresses the generation of uncomfortable sound when the film is rubbed.

B: It is a film that has excellent touch such as flexibility and texture, and is excellent in air permeability and moisture permeability, but it is a film in which the generation of uncomfortable sound is felt.

C: It is a film excellent in air permeability and moisture permeability, but it is a film in which the softness and touch such as touch are not felt, and the generation of uncomfortable sound is felt.

D: A film with insufficient physical properties required for stretched porous films such as air permeability and moisture permeability.

(14-3) Example 201~Example 205 and Comparative Example 201~Comparative Example 204

In consideration of the evaluations shown in (1) to (7) and (9) to (13) above, comprehensive evaluation was performed according to the following criteria.

A: It is a film suitable for applications requiring air permeability or moisture permeability, which has excellent touch such as softness and touch, and suppresses the occurrence of uncomfortable sounds generated when the film is rubbed against, and is A film that has both sufficient heat resistance.

B: It is a film suitable for applications requiring air permeability or moisture permeability, which has excellent tactility such as softness and hand feeling, and suppresses the occurrence of uncomfortable sounds generated when the film is rubbed, but is heat resistant Sex is not enough.

C: It is a film excellent in air permeability and moisture permeability, but it is a film in which the softness and touch such as touch are not felt, and the generation of uncomfortable sound is felt.

D: A film with insufficient physical properties required for stretched porous films such as air permeability and moisture permeability.

The raw materials used in each example and comparative example are as follows.

<Inorganic filler (A)>

． Ground calcium carbonate "Lighton BS-0" (average particle size 1.1 μm, stearic acid surface-treated product) manufactured by Bihoku Powder Chemical Co., Ltd. Hereinafter, it is abbreviated as "A-1".

<polyethylene-based resin (B)>

． Linear low-density polyethylene "NOVATEC LL UF230" manufactured by Nippon Polyethylene Co., Ltd. (density 0.921 g/cm ³ , MFR 1.0 g/10 minutes, melting point 120° C.). Hereinafter, it is abbreviated as "B-1".

． Branched low-density polyethylene "NOVATEC LD LF441" manufactured by Nippon Polyethylene Co., Ltd. (density 0.918 g/cm ³ , MFR 2.3 g/10 minutes, melting point 113° C.). Hereinafter, it is abbreviated as "B-2".

<Soft Polyolefin Resin (C)>

． Metallocene ethylene/α-olefin copolymer "Kernel KF360T" manufactured by Nippon Polyethylene Co., Ltd. (density 0.898 g/cm ³ , MFR 3.5 g/10 minutes, melting point 90° C.). Hereinafter, it is abbreviated as "C-1".

． Ethylene/octene block copolymer "Infuse D9100.05" manufactured by Dow Chemical Co. (density 0.877 g/cm ³ , MFR 1.0 g/10 min, melting point 120° C.). Hereinafter, it is abbreviated as "C-2".

． Ethylene/1-butene copolymer "TAFMER A1050S" manufactured by Mitsui Chemicals Co., Ltd. (density 0.862 g/cm ³ , MFR 1.2 g/10 minutes, melting point 45° C.). Hereinafter, it is abbreviated as "C-3".

． Ethylene/octene block copolymer "Infuse D9107" manufactured by Dow Chemical Company (density 0.866 g/cm ³ , MFR 1 g/10 min, melting point 119° C.). Hereinafter, it is abbreviated as "C-4".

<Polypropylene-based resin (D)>

． Polypropylene "NOVATEC PP SA03" (density 0.900 g/cm ³ , MFR 30 g/10 minutes, melting point 165° C.) manufactured by Japan Polypro Co., Ltd. Hereinafter, it is abbreviated as "D-1".

<Plasticizer (E)>

． Hardened castor oil "HCO-P3" manufactured by KF TRADING Co., Ltd. Hereinafter, it is abbreviated as "E-1".

． Liquid polyester-based plasticizer manufactured by J-PLUS Co., Ltd. Diasizer D600". Hereinafter, it is abbreviated as "E-2".

<Antioxidant>

． Antioxidant "Irganox B225" manufactured by BASF Japan Co., Ltd. Hereinafter, it is abbreviated as "F-1".

<Other resins>

． Mitsui Chemicals Co., Ltd. α-olefin copolymer "absortomer EP-1001" (density 0.84 g/cm ³ , MFR 10 g/10 minutes (230° C. 2.16 kg load)). Hereinafter, it is abbreviated as "G-1".

<Example 101>

After weighing each raw material with the composition ratio shown in Table 1, put it into a Henschel mixer (Henschel mixer), make it mix and disperse for 5 minutes, and use a co-rotating twin-screw extruder to melt-mix at a set temperature of 200°C. After refining, the resin composition is extruded through a T-die head connected to the front end of the co-rotating twin-screw extruder, and extracted by a casting roll (casting roll) set at 50° C., allowing it to cool and solidify. An unstretched film is obtained. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed.

Then, the obtained unstretched film was multiplied by (S)-(T ) draw ratio of 130% (2.3 times the extension ratio), (T)-(U) draw ratio of 130% (2.3 times the extension ratio), and a total of 5.3 times the stretch on the MD. Next, heat processing and relaxation processing were performed with the roll (V) set to 90 degreeC, and the stretched porous membrane was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 1.

<Example 102>

An unstretched film was collected by the same method as in Example 101. Then, the obtained unstretched film was multiplied by (S)-(T ) draw ratio 100% (stretch ratio 2.0 times), (T)-(U) draw ratio 100% (stretch ratio 2.0 times), and a total of 4.0 times stretched on MD. Next, heat processing and relaxation processing were performed with the roll (V) set to 90 degreeC, and the stretched porous membrane was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 1.

<Example 103>

An unstretched film was collected by the same method as in Example 101. Then, the obtained unstretched film was multiplied by (S)-(T ) draw ratio 70% (stretch ratio 1.7 times), (T)-(U) draw ratio 70% (stretch ratio 1.7 times), a total of 2.9 times stretched on MD. Next, heat processing and relaxation processing were performed with the roll (V) set to 90 degreeC, and the stretched porous membrane was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 1.

<Comparative Example 101>

An unstretched film was collected by the same method as in Example 101. Then, the obtained unstretched film was multiplied by (S)-(T ) draw ratio of 40% (stretch ratio 1.4 times), (T)-(U) draw ratio of 40% (stretch ratio 1.4 times), a total of 2.0 times stretched on MD. Next, heat processing and relaxation processing were performed with the roll (V) set to 90 degreeC, and the stretched porous membrane was obtained. Regarding the obtained extended porous Films were evaluated in various ways. Summarize the results in Table 1.

<Example 104>

After weighing each raw material with the composition ratio shown in Table 1, put it into a Henschel mixer, mix and disperse it for 5 minutes, melt and knead at a set temperature of 200°C using a co-rotating twin-screw extruder, and then The resin composition was extruded from a T-die connected to the front end of the co-rotating twin-screw extruder, extracted by a casting roll set at 50° C., cooled and solidified, and an unstretched film was obtained. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed.

Then, the obtained unstretched film was multiplied by (S)-(T ) draw ratio 100% (stretch ratio 2.0 times), (T)-(U) draw ratio 100% (stretch ratio 2.0 times), and a total of 4.0 times stretched on MD. Next, heat processing and relaxation processing were performed with the roll (V) set to 90 degreeC, and the stretched porous membrane was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 1.

<Comparative Example 102>

After weighing each raw material with the composition ratio shown in Table 1, put it into a Henschel mixer, mix and disperse it for 5 minutes, melt and knead at a set temperature of 200°C using a co-rotating twin-screw extruder, and then The resin composition was extruded from a T-die connected to the front end of the co-rotating twin-screw extruder, and extracted by a casting roll set at 50° C., cooled and solidified to obtain an unstretched film. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed.

Then, the obtained unstretched film was placed on a roll (S) set at 60°C with a setting Between the roll (T) at 60°C and the roll (U) set at 60°C, multiply (S)-(T) stretch ratio 130% (stretch ratio 2.3 times), (T)-(U) draw The stretching ratio is 130% (2.3 times the stretching ratio), and a total of 5.3 times stretching is carried out on the MD. Next, heat processing and relaxation processing were performed with the roll (V) set to 90 degreeC, and the stretched porous membrane was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 1.

[Table 1]

The stretched porous films obtained in Examples 101 to 104 are excellent in air permeability or moisture permeability, and have suitable tensile strength at break, elongation at break, heat shrinkage rate, and total light transmittance. In addition, even when the stretched porous membranes obtained in Examples 101 to 104 were rubbed against each other, no uncomfortable sound was felt.

As a result, it is considered that the reason is that the resin composition (Z) constituting the stretched porous membrane of the present invention has tan δ calculated from dynamic viscoelasticity measurement and the porosity of the stretched porous membrane satisfying the range specified in the present invention. Specifically, it is considered that the reason is that the resin composition (Z) constituting the stretched porous membranes of Examples 101 to 104 has a tanδ calculated from a dynamic viscoelasticity measurement of 0.100 or more at -20°C. Therefore, the resin The composition (Z) attenuates the sound transmitted by vibration and contributes to the suppression of unpleasant sounds. In addition, since the porosity of the stretched porous membranes of Examples 101 to 104 is in the range of 25% to 80%, the sound propagating in the connected voids collides with the voids and the wall surface of the resin composition (Z). The frequency of energy loss caused by the increase in frequency helps to suppress uncomfortable sounds.

On the other hand, the film obtained in Comparative Example 101 used the resin composition (Z) satisfying the range of tan δ specified in the present invention in the same manner as in Examples 101 to 103, but the film obtained in Comparative Example 101 The stretched porous membrane deviates from the porosity specified in the present invention. Therefore, although the film obtained in Comparative Example 101 was excellent in softness and touch such as touch, it did not sufficiently suppress unpleasant sounds.

In addition, the film obtained in Comparative Example 102 satisfied the porosity specified in the present invention, but the tan δ at -20°C was less than 0.100, and the suppression of uncomfortable sound was insufficient.

That is, it can be seen that it is important that both the tan δ and the porosity satisfy the ranges specified in the present invention in order to achieve both excellent tactile feeling and suppression of uncomfortable sound generated when the film is rubbed against.

<Example 105>

After weighing each raw material with the composition ratio shown in Table 2, put it into a Henschel mixer, mix and disperse it for 5 minutes, melt and knead at a set temperature of 200°C using a co-rotating twin-screw extruder, and then The resin composition was extruded from a T-die connected to the front end of the co-rotating twin-screw extruder, and extracted by a casting roll set at 50° C., cooled and solidified to obtain an unstretched film with a thickness of 30 μm. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed.

Then, the obtained unstretched film was multiplied by (S)-(T ) draw ratio 100% (stretch ratio 2.0 times), (T)-(U) draw ratio 100% (stretch ratio 2.0 times), and a total of 4.0 times stretched on MD. Next, heat processing and relaxation processing were performed with the roll (V) set to 90 degreeC, and the stretched porous membrane was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 2.

<Example 106>

Except having changed the raw material into the composition ratio shown in Table 2, the unstretched film of thickness 30 micrometers was taken by the same method as Example 105. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 105, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. will end The results are summarized in Table 2.

<Example 107>

Except having changed the raw material into the composition ratio shown in Table 2, the unstretched film of thickness 30 micrometers was taken by the same method as Example 105. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 105, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 2.

<Example 108>

Except having changed the raw material into the composition ratio shown in Table 2, the unstretched film of thickness 50 micrometers was taken by the method similar to Example 105. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 105, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 2.

<Comparative Example 103>

Except having changed the raw material into the composition ratio shown in Table 2, the unstretched film of thickness 50 micrometers was taken by the method similar to Example 105. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 105, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 2.

<Comparative Example 104>

Except having changed the raw material into the composition ratio shown in Table 2, the unstretched film of thickness 50 micrometers was taken by the method similar to Example 105. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 105, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. Summarize the results in Table 2.

[Table 2]

The stretched porous films obtained in Examples 105 to 108 are excellent in air permeability or moisture permeability, and have suitable tensile breaking strength, tensile elongation at break, and total light transmittance. In addition, the time-average sound level (LAeq) when the stretched porous membranes obtained in Examples 105 to 108 were rubbed against each other showed a low value, and no uncomfortable sound was felt.

As a result, it is considered that the reason is that the resin composition (Z) constituting the stretched porous membrane of the present invention has tan δ calculated from the measurement of dynamic viscoelasticity and the porosity of the stretched porous membrane satisfies the range specified in the present invention, and stretching The crystal melting enthalpy (ΔHm) of the porous film is 10 J/g to 45 J/g. Specifically, the reason is considered to be that the resin composition (Z) constituting the stretched porous membrane of Examples 105 to 108 has a tan δ calculated from a dynamic viscoelasticity measurement of 0.100 or more at -20°C. Therefore, the resin The composition (Z) attenuates the sound transmitted by vibration and contributes to the suppression of unpleasant sounds. In addition, it is considered that the reason is that the crystal melting enthalpy (ΔHm) of the stretched porous membranes of Examples 105 to 108 is in the range of 10 J/g to 45 J/g, so there are few crystal components that repel and vibrate when an external force is applied, so The sound produced becomes smaller.

On the other hand, the films obtained in Comparative Example 103 and Comparative Example 104 did not satisfy the preferred ranges of tan δ or crystal melting enthalpy (ΔHm) specified in the present invention, so the suppression of unpleasant sounds was insufficient, and the time-averaged sound Level (LAeq) was shown as a high value.

That is, it can be seen that in order to balance the excellent touch feeling and the suppression of uncomfortable sounds generated when the film is rubbed against, it is important that the tan δ and the porosity of the extended porous film satisfy the range specified in the present invention, preferably The crystal melting enthalpy (ΔHm) of the stretched porous membrane is in the range of 10 J/g to 45 J/g.

<Example 201>

After weighing each raw material with the composition ratio shown in Table 3, put it into a Henschel mixer, make it mix and disperse for 5 minutes, and use a co-rotating twin-screw extruder to melt and knead at a set temperature of 200°C. The resin composition was extruded from a T-die connected to the front end of the co-rotating twin-screw extruder, and extracted by a casting roll set at 50° C., cooled and solidified to obtain an unstretched film with a thickness of 35 μm. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed.

Then, the obtained unstretched film was multiplied by (S)-(T ) draw ratio 100% (stretch ratio 2.0 times), (T)-(U) draw ratio 100% (stretch ratio 2.0 times), and a total of 4.0 times stretched on MD. Next, heat processing and relaxation processing were performed with the roll (V) set to 90 degreeC, and the stretched porous membrane was obtained. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

<Example 202>

Except having changed the raw material into the composition ratio shown in Table 3, the unstretched film of thickness 35 micrometers was taken by the same method as Example 201. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 201, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

<Example 203>

In addition to changing the raw materials to the composition ratio shown in Table 3, by implementing In Example 201, an unstretched film with a thickness of 35 μm was used in the same manner. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 201, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

<Example 204>

Except having changed the raw material into the composition ratio shown in Table 3, the unstretched film of thickness 35 micrometers was taken by the same method as Example 201. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 201, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

<Example 205>

Except having changed the raw material into the composition ratio shown in Table 3, the unstretched film of thickness 35 micrometers was taken by the same method as Example 201. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 201, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

<Comparative example 201>

Except having changed the raw material into the composition ratio shown in Table 3, the unstretched film of thickness 50 micrometers was taken by the same method as Example 201. about the acquired The film was stretched for dynamic viscoelasticity measurements. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 201, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

<Comparative example 202>

Except having changed the raw material into the composition ratio shown in Table 3, the unstretched film of thickness 50 micrometers was taken by the same method as Example 201. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 201, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

<Comparative example 203>

Except having changed the raw material into the composition ratio shown in Table 3, the unstretched film of thickness 30 micrometers was taken by the same method as Example 201. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, the obtained unstretched film was stretched, heat-treated, and relaxed by the same method as in Example 201, whereby a stretched porous film was obtained. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

<Comparative example 204>

Except having changed the raw material into the composition ratio shown in Table 3, the unstretched film of thickness 35 micrometers was taken by the same method as Example 201. With regard to the obtained unstretched film, dynamic viscoelasticity measurement was performed. Then, by the same method as in Example 201 Method The obtained unstretched membrane is stretched, heat-treated and relaxed, thereby obtaining the stretched porous membrane. Various evaluations were performed on the obtained stretched porous membrane. The results are summarized in Table 3.

[table 3]

The stretched porous films obtained in Examples 201 to 205 are excellent in air permeability or moisture permeability, and have suitable tensile breaking strength, tensile elongation at break, and total light transmittance. In addition, when the stretched porous membranes obtained in Examples 201 to 205 were rubbed against each other, the time-average sound level (LAeq) showed a low value, and no uncomfortable sound was felt. Furthermore, in the membrane rupture heat resistance test, the membrane was not ruptured at 120°C, 140°C, and furthermore at 160°C.

As a result, the reason is considered to be that the resin composition (Z) constituting the stretched porous membrane of the present invention has tan δ calculated from dynamic viscoelasticity measurement and the temperature at which the crystal melting peak appears within the range specified in the present invention. Specifically, it is considered that the reason is that the resin composition (Z) constituting the stretched porous membrane of Example 201 to Example 205 has a tanδ calculated from a dynamic viscoelasticity measurement of 0.100 or more at -20°C. Therefore, the resin The composition (Z) attenuates the sound transmitted by vibration and contributes to the suppression of unpleasant sounds. In addition, the stretched porous membranes obtained in Examples 201 to 205 have crystal melting peaks at 140° C. to 200° C., and therefore exhibit high heat resistance.

On the other hand, the films obtained in Comparative Example 201 and Comparative Example 202 did not satisfy the tan δ specified in the present invention, so the suppression of uncomfortable sounds was insufficient, and the time-average sound level (LAeq) showed a high value. In addition, it can be seen that the film obtained in Comparative Example 203 does not have a crystal melting peak in the range of 140°C to 200°C. Therefore, although it is a soft film with suppressed unpleasant sound, the heat resistance required for the stretched porous film is slightly insufficient.

Furthermore, Comparative Example 204 is a film containing an α-olefin copolymer with a density of less than 0.850 g/cm ³ , but it does not satisfy the tan δ specified in the present invention, so the suppression of uncomfortable sounds is insufficient. In other words, it can be seen that in order to provide both the necessary heat resistance to the stretched porous membrane and the suppression of the uncomfortable sound generated when the membrane is rubbed, it is important that both the tan δ and the temperature at which the crystal melting peak appears satisfy the requirements of the present invention. range.

Above, the present invention has been described in association with the most practical and considered preferred implementation form at present, but the present invention is not limited to the implementation form disclosed in the specification of the application. The range and the gist of the invention read throughout the specification or the scope of thought can be appropriately changed, and the stretched porous membrane accompanied by such a change must also be understood as being included in the technical scope of the present invention.

[Industrial availability]

The stretched porous film of the present invention has excellent tactile sensations such as softness and texture, suppresses the generation of uncomfortable sounds generated when the film is rubbed, and is also excellent in air permeability, moisture permeability, and strength. Therefore, it can be suitably used in sanitary products such as disposable diapers and feminine sanitary products using stretched porous films; clothes such as work clothes, pullovers, jackets, medical clothes, and chemical protective clothing; masks, covers, curtains, sheets, and scarves. In applications that require air permeability or moisture permeability.

Claims (16)

An extended porous film comprising a resin composition (Z) containing a thermoplastic resin and an inorganic filler (A), and the storage elastic coefficient (E') of the resin composition (Z) calculated from the measurement of dynamic viscoelasticity and The ratio of loss elastic coefficient (E"), that is, tanδ (=E"/E') is above 0.100 at -20°C, and the porosity is 25%~80%. Among them, as polyolefin resin, the thermoplastic resin includes Polyethylene-based resin (B) and soft polyolefin-based resin (C). The extended porous membrane described in item 1 of the scope of the patent application, wherein the enthalpy of crystallization fusion (△Hm) is 10J/g~45J/g. An extended porous film comprising a resin composition (Z) containing a thermoplastic resin and an inorganic filler (A), and the storage elastic coefficient (E') of the resin composition (Z) calculated from the measurement of dynamic viscoelasticity and The ratio of loss elastic coefficient (E"), that is, tanδ (=E"/E'), is 0.100 or more at -20°C, and has a crystal melting peak (Pm1) at 140°C~200°C. Among them, as polyolefin resin, The thermoplastic resin includes polyethylene resin (B) and soft polyolefin resin (C). The stretched porous membrane according to claim 3, wherein the crystal melting enthalpy (ΔHm1) calculated from the crystal melting peak (Pm1) is 1J/g~10J/g. The extended porous membrane as described in item 3 or item 4 of the scope of the patent application, which further has a crystalline melting peak (Pm2) at 30°C to 130°C, and according to the structure The crystal melting enthalpy (△Hm2) calculated from the crystal melting peak (Pm2) is 10J/g~45J/g. The stretched porous membrane according to claim 1 or claim 3, which comprises 25% to 54% by mass of the thermoplastic resin and 46% to 75% by mass of the inorganic filler (A) The resin composition (Z). The stretched porous film as described in claim 1 or claim 3, wherein the thermoplastic resin further includes a polypropylene-based resin (D). The stretched porous film according to claim 1 or claim 3, wherein the density of the polyolefin resin is not less than 0.850 g/cm ³ and not more than 0.940 g/cm ³ . The stretched porous film according to Claim 8 of the patent application, wherein the density of the polyethylene-based resin (B) is not less than 0.910 g/cm ³ and not more than 0.940 g/cm ³ , and the density of the soft polyolefin-based resin (C ) density is 0.850 g/cm ³ or more and less than 0.910 g/cm ³ . The stretched porous film as described in claim 1 or claim 3, wherein the storage elastic coefficient (E') of the resin composition (Z) calculated from a dynamic viscoelasticity measurement is 8.0× at 20°C Below 10 ⁸ Pa. The extended porous membrane as described in item 1 or item 3 of the scope of the patent application, wherein the moisture permeability is 1000g/(m ² .24h)~15000g/(m ² .24h). The stretched porous membrane as described in claim 1 or claim 3, wherein the tensile breaking strength in the stretching direction is 7N/25mm or more. The stretched porous membrane as described in item 1 or item 3 of the patent application, wherein the tensile elongation at break in the extending direction is 40%~400%. The stretched porous film as described in claim 1 or claim 3, wherein the resin composition (Z) contains 0.1% by mass to 8.0% by mass of the plasticizer (E). A hygienic article, which uses the extended porous membrane described in any one of the first to the fourteenth items of the patent application. A kind of clothing, which uses the extended porous film described in any one of the first to the fourteenth items of the patent application scope.