porous membrane

Abstract

The porous membrane of the present invention comprises at least an olefin resin composition, an inorganic filler, and a triglyceride. The porous membrane comprises 50 to 400 parts by mass of the inorganic filler per 100 parts by mass of the olefin resin composition, and 0.1 to 30 parts by mass of the triglyceride. The triglyceride comprises a group derived from a fatty acid having 16 to 22 carbon atoms, which is a hydrocarbon group without an unsaturated bond or a substituent. The porous membrane is suitable for use as a constituent material for absorbent articles.

Description

Technical Field

[0001] The present invention relates to a porous membrane. Background Art

[0002] Porous films having high water resistance and moisture permeability are known. These porous films are generally produced by uniaxially or biaxially stretching a resin film containing a filler and additives to form a plurality of fine pores.

[0003] For example, Patent Document 1 describes a method for producing a porous membrane by melt-molding a composition containing a polyolefin resin, a filler, and a triglyceride to obtain a film, and then stretching the film into a sheet. In this document, triglyceride is incorporated into the resin to uniformly disperse the filler and improve the anisotropy of the porous membrane.

[0004] Patent Document 2 describes a porous membrane formed by melt-molding a composition containing a polyolefin resin, a filler, and a third component, and then stretching the resulting membrane. The third component is a mixture of (A) hydrogenated castor oil and (B) an ester of a hydroxyl-free carboxylic acid having 8 or more carbon atoms and a polyol having 3 or fewer carbon atoms. In this document, the third component is used to address the issue of transparency in the porous membrane.

[0005] Patent Document 3 describes the use of hydrogenated castor oil, primarily a triglyceride composed of 12-hydroxyoctadecanoic acid and glycerol, as a plasticizer in a porous membrane formed from a resin composition containing polyethylene, an inorganic filler, and a plasticizer. This document describes hydrogenated castor oil as being used to improve the plasticity and ductility of the porous membrane.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 62-10141

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-302828

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2016-089009 Summary of the Invention

[0011] The present invention provides a porous membrane comprising at least an olefin resin composition, an inorganic filler and a triglyceride.

[0012] The filler is contained in an amount of 50 parts by mass or more and 400 parts by mass or less, and the triglyceride is contained in an amount of 0.1 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the olefin resin composition.

[0013] The triglyceride includes a group derived from a fatty acid having 16 to 22 carbon atoms, and the group is a hydrocarbon group having no unsaturated bond and no substituent.

[0014] Furthermore, the present invention provides an absorbent article comprising the porous film. DETAILED DESCRIPTION

[0015] As described in Patent Documents 1 to 3, it is known to incorporate triglyceride into porous membranes to improve their ductility and other properties. However, there is a demand for porous membranes that maintain satisfactory moisture permeability while exhibiting improved leak-proof properties compared to conventional ones.

[0016] Therefore, the present invention relates to an improvement of a porous membrane containing triglyceride, and more specifically, to a porous membrane having higher leakage prevention properties than conventional ones while maintaining satisfactory moisture permeability.

[0017] The present invention is described below based on its preferred embodiments. The porous membrane of the present invention has a large number of micropores. The porous membrane of the present invention has moisture permeability through the micropores. In addition, the porous membrane of the present invention has high water resistance and high leak resistance. The porous membrane of the present invention contains at least an olefin resin composition, an inorganic filler and a triglyceride. In addition to containing these components, the porous membrane of the present invention may also contain various additives to enhance the various properties of the porous membrane.

[0018] In this specification, the term "olefin resin composition" encompasses both the case of containing only one of various olefin resins and the case of containing two or more of various olefin resins. Furthermore, the term "olefin resin composition" refers to a composition consisting solely of various olefin resins, without containing other resins or components other than the resins. It should be noted that this does not prevent the porous membrane of the present invention from containing resins other than the olefin resin.

[0019] The olefin resin composition used in the present invention mainly comprises polymers and copolymers of monoolefins such as ethylene, propylene, and butene, for example, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, and mixtures of any two or more thereof.

[0020] The olefin resin composition used in the present invention preferably has a low density from the viewpoint of imparting satisfactory flexibility to the porous membrane of the present invention and improving the exudation of triglycerides described below and improving the water resistance of the porous membrane. From this viewpoint, the density of the olefin resin composition is preferably less than 0.900 g / cm 3 , more preferably 0.895 g / cm 3 Below, more preferably 0.885 g / cm3 the following.

[0021] In addition, the density of the olefin resin composition used in the present invention is preferably 0.840 g / cm 3 More than 0.850 g / cm 3 More preferably, 0.860 g / cm 3 above.

[0022] In summary, the density of the olefin resin composition is preferably 0.840 g / cm 3 Above and less than 0.900g / cm 3 , more preferably 0.850 g / cm 3 Above and 0.895g / cm 3 Below, more preferably 0.860 g / cm 3 Above and 0.885g / cm 3 the following.

[0023] In order to set the density of the olefin resin composition within the range, the olefin resin composition preferably includes a low-melting-point olefin resin as an olefin resin. In addition, the low-melting-point olefin resin is also used to impart flexibility to the porous membrane of the present invention. The low-melting-point olefin resin is preferably a copolymer of ethylene and alpha olefin (hereinafter, also referred to as "ethylene-alpha olefin copolymer"). As alpha olefin, propylene, 1-butene, 1-pentene and 1-hexene etc. can be enumerated. Particularly, the copolymer of ethylene and alpha olefin formed by metallocene catalyst polymerization can further enhance the strength of the film for tearing, penetration, etc., and is therefore more preferred.

[0024] From the viewpoint of imparting flexibility to the porous membrane of the present invention, the melting point of the low-melting-point olefin resin is preferably less than 90°C, more preferably less than 80°C, and further preferably less than 70°C. In addition, in order to obtain the morphological stability of the porous membrane, the melting point of the low-melting-point olefin resin is preferably 40°C or above. The melting point of the low-melting-point olefin resin having a melting point of less than 90°C contained in the porous membrane is measured by the following method. About 2.0 mg of the porous membrane was used as a sample, and differential scanning calorimetry (DSC) was performed using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Co., Ltd.) in an air environment at a measuring temperature range of 10°C to 260°C, a heating rate of 10°C / min, and an endothermic peak. In the obtained DSC curve, an endothermic peak generated when the low-melting-point olefin resin melts was observed in a temperature range below 90°C, and the melting point of the low-melting-point olefin resin is the temperature of the top of the observed endothermic peak.

[0025] It should be noted that the melting point of the additive contained in the porous membrane and the melting point of the low-melting-point olefin resin can be distinguished by collecting the additive that seeps out of the porous membrane and measuring its melting point. The following method is used to efficiently collect the additive from the porous membrane.

[0026] First, the porous membrane was kneaded at 160° C. and 30 rpm for 10 minutes using Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) to obtain a resin mass.

[0027] The resin block was then pressed using a Labo Press (manufactured by Toyo Seiki Co., Ltd.) at 150° C. and 13 MPa for 1 minute, and then cooled and pressed at room temperature and 13 MPa for 1 minute to obtain a pressed film having a thickness of approximately 0.5 mm.

[0028] Finally, the pressed film is stored at 50°C for one week. This allows more additives to seep out of the pressed film surface than in a porous film state, allowing for efficient collection of the additives. Methods for collecting additives from the pressed film surface include wiping with a wipe or scraping with a spatula.

[0029] From the viewpoint of imparting further flexibility to the porous membrane of the present invention, the density of the low-melting-point olefin-based resin is preferably 0.895 g / cm 3 Below, more preferably 0.885 g / cm 3 Below, more preferably 0.875 g / cm 3 From the viewpoint of maintaining the strength of the porous membrane, the density of the low-melting-point olefin resin is preferably 0.840 g / cm 3 More preferably, 0.850 g / cm 3 More preferably, 0.860 g / cm 3 above.

[0030] In order to ensure that the low-melting-point olefin-based resin satisfies both the preferred density range and the preferred melting point range, the low-melting-point olefin-based resin is preferably a random copolymer.

[0031] In order to impart satisfactory flexibility to the porous membrane of the present invention and to maintain low residual strain after elongation deformation, the olefinic resin composition used in the present invention preferably contains 30 parts by mass or more of the low-melting-point olefinic resin per 100 parts by mass of the olefinic resin composition. To further enhance this advantage, the low-melting-point olefinic resin is more preferably contained in an amount of 35 parts by mass or more, and even more preferably 40 parts by mass or more, per 100 parts by mass of the olefinic resin composition.

[0032] Furthermore, from the perspective of preventing the porous film of the present invention from causing blocking, the olefinic resin composition used in the present invention preferably contains 95 parts by mass or less of the low-melting-point olefinic resin per 100 parts by mass of the olefinic resin composition. From the perspective of further enhancing this advantage, the low-melting-point olefinic resin is more preferably contained in an amount of 92 parts by mass or less, and even more preferably 90 parts by mass or less, per 100 parts by mass of the olefinic resin composition.

[0033] In summary, the olefin resin composition used in the present invention preferably contains 30 parts by mass or more and 95 parts by mass or less of the low-melting-point olefin resin per 100 parts by mass of the olefin resin composition, more preferably 35 parts by mass or more and 92 parts by mass or less, and even more preferably 40 parts by mass or more and 90 parts by mass or less.

[0034] In order to further impart heat resistance, morphological stability, and processability to the porous membrane of the present invention, the olefin resin composition used in the present invention preferably contains a high-melting-point olefin resin in addition to the low-melting-point olefin resin, or contains a high-melting-point olefin resin in place of the low-melting-point olefin resin. From the perspective of taking into account the flexibility of the porous membrane, the density of the high-melting-point olefin resin is preferably relatively low, specifically preferably 0.950 g / cm 3 Below, more preferably 0.940 g / cm 3 Below, more preferably 0.930 g / cm 3 the following.

[0035] In addition, from the viewpoint of preventing blocking, the density of the high melting point olefin resin is preferably 0.900 g / cm 3 More preferably, 0.905 g / cm 3 More preferably, 0.910 g / cm 3 above.

[0036] In summary, the density of the high melting point olefin resin is preferably 0.900 g / cm 3 Above and 0.950g / cm 3 Below, more preferably 0.905g / cm 3 Above 0.940g / cm 3 Below, more preferably 0.910 g / cm 3 Above 0.930g / cm 3 the following.

[0037] The high melting point olefin resin having the above density is preferably polyethylene such as low-density polyethylene or linear low-density polyethylene. In particular, linear low-density polyethylene is preferred because it has improved heat resistance during stretching and can be stretched uniformly. In particular, linear low-density polyethylene polymerized with a metallocene catalyst is more preferred because it further improves the film's strength against tearing, penetration, etc.

[0038] Metallocene catalysts are compounds composed of a metallocene, a transition metal such as titanium, zirconium, or hafnium, sandwiched between unsaturated cyclic compounds containing π-electron cyclopentadienyl or substituted cyclopentadienyl groups, and a co-catalyst such as an aluminum compound. Examples of metallocenes include titanocene and zirconocene. Examples of aluminum compounds include alkylaluminoxanes, alkylaluminums, aluminum halides, and alkylaluminum halides.

[0039] From the perspective of further imparting heat resistance, morphological stability, and processability to the porous film, the olefinic resin composition used in the present invention preferably contains 5 parts by mass or more of a high-melting-point olefinic resin having the above-mentioned density per 100 parts by mass of the olefinic resin composition. From the perspective of further enhancing this advantage, the high-melting-point olefinic resin is more preferably contained in an amount of 8 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the olefinic resin composition.

[0040] Furthermore, from the perspective of achieving both the flexibility of the porous film and the high melting point olefin resin, the olefin resin composition used in the present invention preferably contains 70 parts by mass or less of the high melting point olefin resin per 100 parts by mass of the olefin resin composition. From the perspective of further enhancing this advantage, the high melting point olefin resin is more preferably contained in an amount of 65 parts by mass or less, and even more preferably 60 parts by mass or less, per 100 parts by mass of the olefin resin composition.

[0041] In summary, the olefin resin composition used in the present invention preferably contains 5 parts by mass or more and 70 parts by mass or less of a high-melting-point olefin resin having the above-mentioned density per 100 parts by mass of the olefin resin composition, more preferably 8 parts by mass or more and 65 parts by mass or less, and even more preferably 10 parts by mass or more and 60 parts by mass or less.

[0042] In order to achieve high-speed forming of the porous membrane to be melt-formed and to achieve short-time solidification, the melting point of the high-melting-point olefin resin used in the present invention is preferably 95°C or above, more preferably 100°C or above, and even more preferably 110°C or above. The melting point of the high-melting-point olefin resin contained in the porous membrane is measured by the following method. About 2.0 mg of the porous membrane is used as a sample, and a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Co., Ltd.) is used to perform differential scanning calorimetry (DSC) under the conditions of a measurement temperature range of 10°C to 260°C, a heating rate of 10°C / min, and an air environment. An endothermic peak generated when the high-melting-point olefin resin melts is observed in the temperature region above 95°C of the obtained DSC curve, and the apex of the endothermic peak is the melting point of the high-melting-point olefin resin. The method for distinguishing the additive contained in the porous membrane from the high-melting-point olefin-based resin is the same as the method for distinguishing the additive contained in the porous membrane from the low-melting-point olefin-based resin.

[0043] A preferred embodiment of the present invention includes an olefin resin composition comprising an ethylene-α-olefin copolymer polymerized with a metallocene catalyst as a low-melting-point polyethylene resin and a linear low-density polyethylene polymerized with a metallocene catalyst as a high-melting-point polyethylene resin. The porous membrane of this embodiment has very high flexibility.

[0044] The inorganic filler used in the present invention is a material that peels off at the interface with the olefin resin composition to form micropores. From this viewpoint, the average particle size D of the inorganic filler is 50 The average particle size D of the inorganic filler is preferably 30 μm or less, more preferably 10 μm or less, and preferably 0.5 μm or more, more preferably 1 μm or more. 50 It is a weight cumulative particle size at a cumulative weight of 50% by mass obtained by a laser diffraction scattering particle size distribution measurement method.

[0045] Examples of the inorganic filler include calcium carbonate, gypsum, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium phosphate, aluminum hydroxide, zinc oxide, titanium oxide, aluminum oxide, mica, zeolite, carbon black, and mixtures thereof. Calcium carbonate is particularly preferred because it can be easily adjusted to the above-mentioned particle size.

[0046] In order to form a sufficient number of micropores and sufficiently improve the moisture permeability of the porous film, the inorganic filler is preferably contained in an amount of 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 80 parts by mass or more per 100 parts by mass of the olefin resin composition.

[0047] From the viewpoint of sufficiently improving the leakproofness of the porous membrane, the inorganic filler is preferably contained in an amount of 400 parts by mass or less, more preferably 300 parts by mass or less, and even more preferably 200 parts by mass or less per 100 parts by mass of the olefin resin composition.

[0048] The porous membrane of the present invention contains triglycerides. Triglycerides are mainly used as a water repellent to improve the water resistance of the porous membrane and improve the leak-proofness. In the technical field of porous membranes, triglycerides have been added to porous membranes in the past, but the type of triglycerides used in the present invention is different from the triglycerides used in the past in this technical field. In detail, the triglycerides used in the present invention contain a group derived from a fatty acid having 16 or more and 22 or less carbon atoms, and the group is a hydrocarbon group without an unsaturated bond and a substituent. The research results of the present inventors have shown that by using this triglyceride, the water resistance of the porous membrane containing the triglyceride is higher than before, and the leak-proofness of the porous membrane is higher than before.

[0049] Furthermore, the present inventors' research results have also shown that the inclusion of the triglyceride in the porous membrane has the additional effect of making it less likely for blocking to occur even when the porous membrane contains the low-melting-point olefin resin. It is known that membranes containing low-melting-point olefin resins are generally prone to blocking.

[0050] From the viewpoint of making the above advantages more significant, the amount of the triglyceride incorporated into the porous membrane of the present invention is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 parts by mass or more, relative to 100 parts by mass of the olefin resin composition.

[0051] From the viewpoint of improving moldability and suppressing a decrease in the strength of the porous film, the amount of the triglyceride added is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 parts by mass of the olefin resin composition.

[0052] In summary, the amount of triglyceride added per 100 parts by mass of the olefin resin composition is preferably 0.1 parts by mass to 30 parts by mass, more preferably 0.5 parts by mass to 25 parts by mass, and even more preferably 1.0 parts by mass to 20 parts by mass.

[0053] The triglyceride used in the present invention is represented by the following formula (1).

[0054] [Chemical Formula 1]

[0055]

[0056] Where R 1 to R3 R represents the same or different hydrocarbon groups. 1 to R 3 At least one of the groups is preferably a group derived from a fatty acid having 16 to 22 carbon atoms, and the group is a hydrocarbon group having no unsaturated bond and no substituent. It should be noted that the alkyl group of palmitic acid, which is a fatty acid having 16 carbon atoms, has 15 carbon atoms.

[0057] A "hydrocarbon group without unsaturated bonds" is a hydrocarbon group without either a carbon-carbon double bond or a triple bond. In other words, it is an alkyl group. Furthermore, an "unsubstituted hydrocarbon group" means that the hydrogen atoms contained in the hydrocarbon group are not replaced by other atoms or atomic groups (e.g., hydroxyl groups). Therefore, a "hydrocarbon group without unsaturated bonds or substituents" is synonymous with an unsubstituted alkyl group.

[0058] In the following description, for convenience, the triglyceride used in the present invention is also referred to as "the triglyceride of the present invention."

[0059] Among the triglycerides represented by formula (1), R 1 to R 3 At least one of them is preferably a group derived from a fatty acid having 18 carbon atoms, and the group is a hydrocarbon group having no unsaturated bond and no substituent.

[0060] In the triglyceride represented by formula (1), R 1 to R 3 When either or both of them are groups other than a group derived from a fatty acid having 16 or more and 22 or less carbon atoms (the group is a hydrocarbon group having no unsaturated bonds and no substituents), the group can be a group derived from a fatty acid, and the type thereof is not particularly limited. From the viewpoint of obtaining a porous membrane with higher water resistance, the group preferably does not have an unsaturated bond and no substituents.

[0061] The triglyceride of the present invention preferably has the carbon number of the fatty acid residue adjusted. This can improve the water resistance of the film. Specifically, the triglyceride is preferably (A) or (B) below.

[0062] (A) A triglyceride comprising a mixture of a triglyceride containing at least a group derived from a fatty acid having 18 carbon atoms in one molecule and a triglyceride containing at least a group derived from a fatty acid having 16 to 22 carbon atoms (excluding a fatty acid having 18 carbon atoms) in one molecule.

[0063] (B) A triglyceride containing in one molecule at least one group derived from a saturated fatty acid having 18 carbon atoms and at least one group derived from a saturated fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms).

[0064] In particular, from the perspective of further improving water resistance, the triglyceride preferably contains at least one group derived from a saturated fatty acid having 18 carbon atoms and at least one group derived from a saturated fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms) in one molecule.

[0065] As a specific example, the combination of a fatty acid having 18 carbon atoms and a fatty acid having 16 carbon atoms is shown in (C) or (D) below.

[0066] (C) A triglyceride comprising a mixture of a triglyceride containing in one molecule at least a group derived from a fatty acid having 18 carbon atoms (i.e., stearic acid) (the group being a hydrocarbon group having no unsaturated bond and no substituent) and a triglyceride containing in one molecule at least a group derived from a fatty acid having 16 carbon atoms (i.e., palmitic acid) (the group being a hydrocarbon group having no unsaturated bond and no substituent).

[0067] (D) A triglyceride containing in one molecule at least one group derived from a fatty acid having 18 carbon atoms (the group being a hydrocarbon group having no unsaturated bond or substituent) and at least one group derived from a fatty acid having 16 carbon atoms (the group being a hydrocarbon group having no unsaturated bond or substituent).

[0068] As shown in the case of (C), when the triglyceride of the present invention comprises a plurality of triglycerides, it is preferred that at least one triglyceride contains at least one group derived from a saturated fatty acid having 16 carbon atoms in one molecule (this triglyceride is also referred to as "triglyceride 16"). Triglyceride 16 may contain one group derived from a saturated fatty acid having 16 carbon atoms in one molecule (this triglyceride is also referred to as "triglyceride P"), two groups (this triglyceride is also referred to as "triglyceride PP"), or three groups (this triglyceride is also referred to as "triglyceride PPP").

[0069] The types of the remaining fatty acid residues in triglyceride P and triglyceride PP are not particularly limited, and may be, for example, residues of saturated fatty acids having 12 to 24 carbon atoms.

[0070] The triglyceride 16 may consist of only triglyceride P, only triglyceride PP, or only triglyceride PPP.

[0071] Triglyceride 16 may be a combination of two or more selected from triglyceride P, triglyceride PP, and triglyceride PPP. For example, triglyceride 16 may be a combination of triglyceride P and triglyceride PP, a combination of triglyceride P and triglyceride PPP, a combination of triglyceride PP and triglyceride PPP, or a combination of triglyceride P, triglyceride PP, and triglyceride PPP.

[0072] As shown in the case of (C), even when the triglyceride of the present invention comprises a plurality of triglycerides, it is preferred that at least one triglyceride contain at least one group derived from a saturated fatty acid having 18 carbon atoms in one molecule (this triglyceride is also referred to as "triglyceride 18"). Triglyceride 18 may contain one group derived from a fatty acid having 18 carbon atoms in one molecule (this triglyceride is also referred to as "triglyceride S"), two groups (this triglyceride is also referred to as "triglyceride SS"), or three groups (this triglyceride is also referred to as "triglyceride SSS").

[0073] The types of the remaining fatty acid residues in triglyceride S and triglyceride SS are not particularly limited, and may be, for example, residues of saturated fatty acids having 12 to 24 carbon atoms.

[0074] The triglyceride 18 may consist of only triglyceride S, only triglyceride SS, or only triglyceride SSS.

[0075] Triglyceride 18 may be a combination of two or more selected from triglyceride S, triglyceride SS, and triglyceride SSS. For example, triglyceride 18 may be a combination of triglyceride S and triglyceride SS, a combination of triglyceride S and triglyceride SSS, a combination of triglyceride SS and triglyceride SSS, or a combination of triglyceride S, triglyceride SS, and triglyceride SSS.

[0076] In the case of (C), the triglyceride of the present invention may be composed solely of triglyceride 16 and triglyceride 18, or may further contain other triglycerides in addition to triglyceride 16 and triglyceride 18. Examples of the other triglycerides include triglycerides having no groups derived from fatty acids having 16 to 22 carbon atoms, and triglycerides containing groups derived from fatty acids having 16 to 22 carbon atoms (excluding triglyceride 16 and triglyceride 18).

[0077] Assuming that the group derived from a saturated fatty acid with 16 carbon atoms is "P," the group derived from a saturated fatty acid with 18 carbon atoms is "S," and the groups derived from fatty acids other than the saturated fatty acids with 16 carbon atoms and 18 carbon atoms are "X" and "Y," examples of combinations of aliphatic groups constituting the triglycerides of the present invention include PPP, SSS, PPX, SSX, PXY, SXY, PPS, PSS, and PSX. The structures of the triglycerides represented by PPX, SSX, PXY, SXY, and PSX are shown below (a) to (m). It should be noted that the structures of PPS and PSS are not shown, but the structure of PPS follows that of PPX, and the structure of PSS follows that of SSX.

[0078] [Chemical Formula 2]

[0079]

[0080] [Chemical Formula 3]

[0081]

[0082] [Chemical Formula 4]

[0083]

[0084] [Chemical Formula 5]

[0085]

[0086] [Chemical Formula 6]

[0087]

[0088] The triglycerides of the present invention can be used singly from any of the various triglycerides described above. For example, in the case of (D), the triglycerides of the present invention may include a triglyceride containing at least one group derived from a saturated fatty acid having 16 carbon atoms, at least one group derived from a saturated fatty acid having 18 carbon atoms, and no groups derived from fatty acids other than these in one molecule. Alternatively, the triglycerides of the present invention may include a triglyceride containing one group derived from a saturated fatty acid having 16 carbon atoms, one group derived from a saturated fatty acid having 18 carbon atoms, and one group derived from another fatty acid.

[0089] The triglyceride of the present invention may be a combination of two or more of the various triglycerides described above. For example, the triglyceride of the present invention may be a combination of (C) and (D). Alternatively, it may be a combination of two or more of (D).

[0090] Furthermore, the triglyceride of the present invention may be a combination of one or more of the above triglycerides and other triglycerides. Examples of other triglycerides include triglycerides containing a group derived from a fatty acid having 14 to 22 carbon atoms (excluding triglyceride 16 and triglyceride 18).

[0091] In the present invention, from the viewpoint of further improving the water resistance of the porous membrane of the present invention, it is preferred to use the above-mentioned various triglycerides alone or in combination of two or more thereof.

[0092] From the viewpoint of obtaining a porous membrane with higher water resistance, the triglyceride contained in the porous membrane of the present invention is preferably a group derived from a fatty acid having 18 carbon atoms (the group is a hydrocarbon group without unsaturated bonds and substituents) in an amount of more than 28 mass % and less than 96 mass %, especially more than 28 mass % and less than 70 mass %, especially more than 29 mass % and less than 67 mass %, and especially more than 30 mass % and less than 64 mass %, relative to the total amount of groups derived from fatty acids contained in all triglycerides.

[0093] In addition, from the perspective of further improving the water resistance of the porous membrane and shortening the time it takes for water resistance to develop, the triglycerides contained in the porous membrane of the present invention preferably contain 28% by mass or more and 68% by mass or less of the total amount of the fatty acid-derived groups contained in all triglycerides, which are groups derived from fatty acids having 18 carbon atoms (these groups are hydrocarbon groups without unsaturated bonds or substituents), and 26% by mass or more and 70% by mass or less of the groups derived from fatty acids having 16 carbon atoms (these groups are hydrocarbon groups without unsaturated bonds or substituents). However, this is provided that the total proportion of the groups derived from fatty acids having 18 carbon atoms and the proportion of the groups derived from fatty acids having 16 carbon atoms does not exceed 100% by mass.

[0094] In this case, the ratio of the group derived from the fatty acid having 18 carbon atoms is more preferably 29% by mass or more and 66% by mass or less, and even more preferably 30% by mass or more and 64% by mass or less.

[0095] On the other hand, the proportion of groups derived from fatty acids having 16 carbon atoms is more preferably 27% by mass or more and 69% by mass or less, and even more preferably 28% by mass or more and 68% by mass or less. When the proportion of groups derived from fatty acids having 16 carbon atoms is high, triglycerides are more likely to precipitate on the surface of the porous membrane, shortening the time it takes for water repellency to be exhibited.

[0096] From the perspective of improving the thermal stability of the porous membrane and further improving the water resistance of the porous membrane, the triglyceride contained in the porous membrane of the present invention preferably comprises, relative to the total amount of the fatty acid-derived groups contained in all triglycerides, 28% by mass or more and 47% by mass or less of groups derived from fatty acids having 18 carbon atoms (these groups are hydrocarbon groups without unsaturated bonds or substituents), and 40% by mass or more and 60% by mass or less of groups derived from fatty acids having 22 carbon atoms (these groups are hydrocarbon groups without unsaturated bonds or substituents). This is provided that the total proportion of the groups derived from fatty acids having 18 carbon atoms and the proportion of the groups derived from fatty acids having 22 carbon atoms does not exceed 100% by mass.

[0097] In this case, the ratio of the group derived from the fatty acid having 18 carbon atoms is more preferably 30% by mass or more and 45% by mass or less, and even more preferably 32% by mass or more and 43% by mass or less.

[0098] On the other hand, the proportion of groups derived from fatty acids with 22 carbon atoms is more preferably 42% by mass or more and 58% by mass or less, and even more preferably 44% by mass or more and 56% by mass or less. A high proportion of groups derived from fatty acids with 22 carbon atoms increases the melting point of the triglyceride and the thermal stability of the molded product. Furthermore, contamination of the rollers of the processing machine can be reduced.

[0099] The ratio of each of the groups derived from fatty acids having 16 carbon atoms, the groups derived from fatty acids having 18 carbon atoms, and the groups derived from fatty acids having 22 carbon atoms, based on the total amount of the groups derived from fatty acids contained in all triglycerides, was measured by the following method.

[0100] The triglyceride that seeped out to the surface of the membrane was wiped off with a cellulose wipe.

[0101] The ester bonds in the obtained triglycerides were hydrolyzed with an alkali, and the methyl-esterified fatty acids were quantitatively analyzed by gas chromatography.

[0102] It should be noted that whether there are alkyl chains with different carbon numbers in one molecule of triglyceride can be determined by TOF-MS (time-of-flight mass spectrometry). In detail, the molecular weight distribution of triglyceride is measured by TOF-MS, and whether the molecule contains alkyl chains with different carbon numbers is determined based on the molecular weight of one molecule. Whether a compound with the same molecular weight has alkyl chains with different carbon numbers in one molecule can be determined by a tandem mass spectrometer (MS / MS) as a mass spectrometer. It is determined as follows: a specific ion is selected using a first mass separation unit, collides with an inert gas to generate fragment ions, and the fragment ions are separated and detected using a second mass separation unit.

[0103] From the perspective of further improving the water resistance of the porous membrane of the present invention, the triglycerides of the present invention preferably do not contain groups derived from unsaturated fatty acids. "No unsaturated fatty acid-derived groups" includes both cases where the triglycerides do not contain any unsaturated fatty acid-derived groups and cases where a small amount of unsaturated fatty acids is unavoidably contained. Cases where a small amount of unsaturated fatty acids is unavoidably contained include, for example, cases where the proportion of unsaturated fatty acid-derived groups is 2% by mass or less based on the total amount of fatty acid-derived groups contained in all triglycerides contained in the porous membrane.

[0104] As described above, from the perspective of further improving the water resistance of the porous membrane of the present invention, the triglyceride of the present invention preferably does not contain groups derived from fatty acids having hydroxyl groups. A fatty acid having a hydroxyl group is a fatty acid in which at least one hydrogen atom in the hydrocarbon group of the fatty acid is substituted with a hydroxyl group. The absence of groups derived from fatty acids having hydroxyl groups includes both the case where there are no groups derived from fatty acids having hydroxyl groups at all and the case where a small amount of groups derived from fatty acids having hydroxyl groups is unavoidable. The case where a small amount of groups derived from fatty acids having hydroxyl groups is unavoidable includes, for example, the case where the proportion of groups derived from fatty acids having hydroxyl groups is 2% by mass or less based on the total amount of groups derived from fatty acids contained in all triglycerides contained in the porous membrane.

[0105] From the perspective of further improving the water resistance of the porous membrane of the present invention, it is preferred that all the fatty acid-derived groups contained in the triglycerides in the porous membrane of the present invention are hydrocarbon groups without unsaturated bonds. Furthermore, it is preferred that all the fatty acid-derived groups contained in the triglycerides are hydrocarbon groups without substituents.

[0106] The porous membrane of the present invention may contain only triglyceride as the glyceride, or may contain monoglyceride and / or diglyceride in addition to triglyceride within a range that exhibits the intended effects of the present invention.

[0107] The porous membrane of the present invention may further contain additives in addition to the triglyceride. The additives are those that can impart various additional properties to the porous membrane. Examples of such additives include dispersants for inorganic fillers and plasticizers. It should be noted that the additives do not include the triglyceride.

[0108] As the dispersant, it is preferred to use a substance that can hydrophobize the surface of the inorganic filler. From this viewpoint, a fatty acid is preferably used as the dispersant. Examples of fatty acids include caprylic acid, palmitic acid, stearic acid, capric acid, oleic acid, myristic acid, and lauric acid.

[0109] The plasticizer is used to impart flexibility and elasticity to the porous membrane of the present invention or to prevent the porous membrane of the present invention from producing a rustling sound. As the plasticizer, monoesters, polyesters, ethylene-α-olefin copolymers, low molecular weight polyethylene, olefin oligomers, liquid polyisoprene, liquid polybutadiene, etc. are preferably used.

[0110] Monoesters are compounds obtained from monobasic acids and monohydric alcohols.

[0111] On the other hand, polyester is a compound obtained from any combination of a polybasic acid and a monohydric alcohol, a monobasic acid and a polyhydric alcohol, or a polybasic acid and a polyhydric alcohol.

[0112] Ethylene-α-olefin co-oligomers are low molecular weight copolymers of α-olefins such as propylene, 1-butene, 1-pentene and 1-hexene with ethylene.

[0113] As the monobasic acid, polybasic acid, monohydric alcohol, and polyhydric alcohol, for example, the following are preferably used.

[0114] Examples of the monobasic acid include monocarboxylic acids of long-chain hydrocarbons having 10 to 22 carbon atoms.

[0115] Examples of the polybasic acid include dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acids.

[0116] Examples of the monohydric alcohol include monoalcohols of long-chain hydrocarbons having 10 to 22 carbon atoms.

[0117] Examples of the polyol include glycols, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, and sucrose.

[0118] Particularly preferred polyesters include, for example, polyesters obtained by capping part or all of the carboxylic acids or alcohols at both ends of a polyester of diethylene glycol and dimer acid with stearyl alcohol or stearic acid, polyesters of 1,3-butanediol and adipic acid, hexaesters of trimethylolpropane-adipic acid-stearic acid, octaesters of pentaerythritol-adipic acid-stearic acid, and dodecyl esters of dipentaerythritol-adipic acid-stearic acid.

[0119] On the other hand, particularly preferred monoesters include, for example, esters having a total carbon number of 30 or more obtained by dehydrating a monocarboxylic acid having 1 to 40 carbon atoms and a monoalcohol having 1 to 40 carbon atoms. Among these, esters having a total carbon number of 30 or more obtained from a monocarboxylic acid and a monoalcohol having 1 to 40 carbon atoms are preferred, and branched monoesters having a carbon number of 38 or more are more preferred. Specific examples include isodecyl stearate, isodecyl behenate, isotridecyl stearate, 2-octadecyl stearate, 2-decyltetradecyl laurate, 2-decyltetradecyl stearate, 2-octadecyl behenate, stearyl isostearate, esters of stearic acid and a C20 Guerbet alcohol, and esters of α-branched fatty acids (having 18 to 40 carbon atoms) and monoalcohols (having 6 to 36 carbon atoms).

[0120] In addition to the aforementioned additives, the moisture permeable film may also contain a pore opening promoter. The pore opening promoter is used to smoothly stretch the resin composition comprising the resin and the inorganic filler to form micropores. As described above, from the perspective of improving the flexibility of the moisture permeable film, it is preferred that the moisture permeable film contain a low-melting-point olefin resin. However, low-melting-point olefin resins are relatively resistant to interfacial delamination with the inorganic filler. Therefore, in addition to using a low-melting-point olefin resin as the raw material for the moisture permeable film, a pore opening promoter is also used to promote this interfacial delamination.

[0121] As the pore-forming promoter, substances known as release agents for metals and resins are preferably used. Specific examples include metal soaps, silicones, fluororesins, fatty amides, and hydrocarbon waxes. Metal soaps are particularly preferred because they facilitate the formation of fine pores.

[0122] As the metal soap, metal salts of fatty acids are preferably used. Examples of fatty acids include caprylic acid, palmitic acid, stearic acid, capric acid, oleic acid, myristic acid, and lauric acid. Examples of metal salts include calcium, aluminum, magnesium, and zinc salts of these fatty acids.

[0123] From the viewpoint of sufficiently improving the flexibility of the porous film and the dispersibility of the inorganic filler, the amount of the additive is preferably 0.01 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more relative to 100 parts by mass of the olefin resin composition.

[0124] In addition, from the perspective of improving formability and suppressing the decrease in strength of the porous film, the amount of the additive is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and further preferably 16 parts by mass or less relative to 100 parts by mass of the olefin resin composition.

[0125] The additives may include at least a first additive having an SP value that differs from the triglyceride by less than 0.37. To ensure that this additive can be added without inhibiting the water resistance exhibited by the triglyceride of the present invention, the first additive is preferably included in an amount of 3.5 parts by mass or less per 100 parts by mass of the olefin resin composition, inorganic filler, and triglyceride combined. To improve leakproofness without impairing water resistance, the first additive is preferably included in an amount of 0.01 parts by mass to 3.5 parts by mass, more preferably 0.03 parts by mass to 3.3 parts by mass, and even more preferably 0.06 parts by mass to 3.2 parts by mass, based on a total of 100 parts by mass of the olefin resin composition, inorganic filler, and triglyceride combined.

[0126] Furthermore, the additive may include at least a second additive having an SP value that differs from the triglyceride by 0.37 or more. From the perspective of allowing the addition of this additive without inhibiting the water resistance exhibited by the triglyceride of the present invention, the second additive is preferably included in an amount of 10 parts by mass or less relative to a total of 100 parts by mass of the olefin resin composition, inorganic filler, and triglyceride. If the additive includes the second additive, from the perspective of improving leakproofness without impairing water resistance, the second additive is preferably included in an amount of 0.01 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less, and even more preferably 1.5 parts by mass or more and 6 parts by mass or less, relative to a total of 100 parts by mass of the olefin resin composition, inorganic filler, and triglyceride.

[0127] As mentioned above, in the technical field of porous membranes, triglycerides have been incorporated into porous membranes. However, the present inventors' research results have shown that randomly incorporating additives into porous membranes containing triglycerides can inhibit the water resistance provided by the triglycerides. In response to this, if a first additive is used in an amount of 3.5 parts by mass or less relative to a total of 100 parts by mass of the olefin resin composition, inorganic filler, and triglyceride, or a second additive is used in an amount of 10 parts by mass or less relative to a total of 100 parts by mass of the olefin resin composition, inorganic filler, and triglyceride, the additive can be incorporated without inhibiting the water resistance exhibited by the triglyceride of the present invention. From the perspective of making this advantage more significant, the difference in SP value between the triglyceride of the present invention and the second additive is more preferably 0.50 or more, and more preferably 0.60 or more. In addition, the difference is preferably 4.00 or less, more preferably 3.00 or less, and more preferably 1.50 or less.

[0128] The SP value is a physical property known as the solubility parameter. Two substances with similar SP values ​​have the property of mixing well. In other words, two substances with similar SP values ​​have high compatibility. Therefore, when comparing the SP value of the triglyceride of the present invention with the SP value of an additive, the SP value of the triglyceride of the present invention may be higher, or the SP value of the additive may be higher. From the perspective of less likely to inhibit the water resistance of the triglyceride of the present invention resulting from the additive, the SP value of the triglyceride is preferably higher than the SP value of the additive.

[0129] Examples of the first additive selected so as to have an SP value difference of less than 0.37 from the triglyceride of the present invention include some of the fatty acids, alcohols, monoesters, polyesters, and metal soaps exemplified as the dispersant, plasticizer, and cell-opening promoter.

[0130] Examples of the second additive selected so as to have an SP value difference of 0.37 or greater with the triglyceride of the present invention include olefin oligomers, ethylene-α-olefin cooligomers, low molecular weight polyethylene, silicone rubber, fluororubber, fluororesin, and polystyrene. In the present invention, the second additive may be used alone or in combination with the first additive. Depending on the circumstances, the first additive may be used alone.

[0131] The SP value was calculated by the Fedors method [RFFEDORS, POLYM.ENG.SCI.14,147(1974)], and the unit was (cal / cm 3 ) 1 / 2 express.

[0132] When the triglyceride of the present invention is contained in a porous membrane in a plurality of types, the SP value δmix of the mixture shown below is calculated.

[0133] δmix=Σδiφi(cal / cm 3 ) 1 / 2

[0134] In the formula, δi represents the SP value of each component constituting the mixture, and φi represents the volume fraction of the component.

[0135] The porous membrane of the present invention is obtained by melt-molding a raw material composition containing an olefin resin composition, an inorganic filler, a triglyceride, and additives to form a resin sheet, and stretching the resin sheet in at least a uniaxial direction.

[0136] The porous membrane of the present invention can be efficiently produced by, for example, the following method.

[0137] First, the components of the raw material composition are pre-mixed using a Henschel mixer, high-speed mixer, or the like, and then kneaded using a single-screw or twin-screw extruder to form pellets. The pellets are then formed into a film using a molding machine to obtain a resin sheet. Examples of the molding machine that can be used include a T-die type or an inflation type.

[0138] About the resin sheet, by being subjected to uniaxial or biaxial stretching, the interface peeling of olefin resin composition and inorganic filler is produced and porosity is made. This stretching uses a roller method that can be stretched along the mechanical direction, a tentering method that can be stretched along the width direction in addition to the mechanical direction, etc. In this way, the porous film of the present invention is obtained. The resin sheet is preferably stretched to more than 1.1 times along the uniaxial direction, more preferably stretched to more than 1.5 times, and further preferably stretched to more than 2 times, so that the area increases with stretching. In addition, with respect to the viewpoint of avoiding the reduction of tear strength due to excessive molecular orientation caused by excessive stretching, it is preferably stretched to less than 5.0 times, more preferably stretched to less than 4.5 times, and further preferably stretched to less than 4 times.

[0139] The weight per unit area of ​​the porous membrane of the present invention also depends on its application, and can be set to 5 g / m 2 Above and 100g / m 2 The thickness of the porous membrane of the present invention also depends on its application, and can be set to about 4 μm or more and 90 μm or less, for example.

[0140] The porous film of the present invention has moisture permeability and is suitable for applications requiring both breathability and leak-proof properties. For example, the porous film of the present invention can be used as leak-proof sheets for absorbent articles such as disposable diapers and sanitary napkins, and as waterproof sheets for rain gear.

[0141] The porous film of the present invention is particularly useful as a component of an absorbent article. The present invention includes an absorbent article comprising the porous film of the present invention.

[0142] The absorbent article of the present invention typically comprises a topsheet forming a skin-facing surface, a leak-proof sheet forming a non-skin-facing surface, and a liquid-retaining absorbent body disposed between these two sheets. The absorbent article may further comprise leak-proof cuffs on both sides of the skin-facing surface along the longitudinal direction.

[0143] The facesheet is typically liquid permeable.

[0144] The absorbent body typically comprises an absorbent core and a core wrapper surrounding the absorbent core.

[0145] The porous film of the present invention is particularly effective and preferred when used as a leak-proof sheet or leak-proof cuff.

[0146] When the porous film of the present invention is used as a leak-proof sheet or leak-proof cuff for an absorbent article, the porous film itself may be used as the leak-proof sheet or the porous film may be used in combination with other sheet materials such as nonwoven fabric.

[0147] It should be noted that the "skin-facing surface" is the surface of the absorbent article or its constituent component (such as the absorbent core) facing the wearer's skin when the absorbent article is worn, that is, the side relatively close to the wearer's skin, and the "non-skin-facing surface" is the side of the absorbent article or its constituent component opposite to the skin side when the absorbent article is worn, that is, the side facing the side relatively away from the wearer's skin.

[0148] The surface sheet, absorbent core, and core wrapping sheet can be used as generally used in such absorbent articles without particular limitation.

[0149] The absorbent article of the present invention broadly encompasses articles for absorbing body fluids (urine, loose stools, menstrual blood, sweat, etc.) discharged from the human body, and includes, for example, disposable diapers, sanitary napkins, sanitary underwear, incontinence pads, and the like.

[0150] Regarding the above-mentioned embodiment, the present invention further discloses the following porous membrane.

[0151] <1>

[0152] A porous film comprising at least an olefin resin composition, an inorganic filler and triglyceride,

[0153] The filler is contained in an amount of 50 parts by mass or more and 400 parts by mass or less, and the triglyceride is contained in an amount of 0.1 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the olefin resin composition.

[0154] The triglyceride includes a group derived from a fatty acid having 16 to 22 carbon atoms, and the group is a hydrocarbon group having no unsaturated bond and no substituent.

[0155] <2>

[0156] The porous membrane according to <1>, wherein the triglyceride is:

[0157] (A) a mixture of a triglyceride containing in one molecule at least a group derived from a fatty acid having 18 carbon atoms and a triglyceride containing in one molecule at least a group derived from a fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms); or

[0158] (B) A triglyceride containing in one molecule at least one group derived from a saturated fatty acid having 18 carbon atoms and at least one group derived from a saturated fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms).

[0159] <3>

[0160] A porous membrane as described in <1> or <2>, wherein the triglyceride is a triglyceride that contains at least one group derived from a saturated fatty acid having 18 carbon atoms and at least one group derived from a saturated fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms) in one molecule.

[0161] <4>

[0162] The porous membrane according to any one of <1> to <3>, wherein 28% by mass or more and 96% by mass or less of the total amount of the fatty acid-derived groups contained in all triglycerides are groups derived from a fatty acid having 18 carbon atoms.

[0163] <5>

[0164] The porous membrane according to any one of <1> to <4>, wherein 28% by mass or more and 70% by mass or less of the total amount of the fatty acid-derived groups contained in all triglycerides are groups derived from a fatty acid having 18 carbon atoms.

[0165] <6>

[0166] The porous membrane as described in any one of <1> to <5>, wherein, with respect to the total amount of groups derived from fatty acids contained in all triglycerides, 28% by mass or more and 68% by mass or less are groups derived from fatty acids having 18 carbon atoms, and 26% by mass or more and 70% by mass or less are groups derived from fatty acids having 16 carbon atoms.

[0167] <7>

[0168] The porous membrane as described in any one of <1> to <5>, wherein, with respect to the total amount of the groups derived from fatty acids contained in all triglycerides, 28% by mass or more and 47% by mass or less are groups derived from fatty acids having 18 carbon atoms, and 40% by mass or more and 60% by mass or less are groups derived from fatty acids having 22 carbon atoms.

[0169] <8>

[0170] The porous membrane according to any one of <1> to <7>, wherein the fatty acid-derived groups contained in all the triglycerides are hydrocarbon groups having no unsaturated bond.

[0171] <9>

[0172] The porous membrane according to any one of <1> to <8>, wherein the fatty acid-derived groups contained in all the triglycerides are hydrocarbon groups having no substituent.

[0173] <10>

[0174] The porous film according to any one of <1> to <9>, wherein the density of the olefin-based resin composition is less than 0.900 g / cm 3 ,and

[0175] The density of the olefin resin composition is 0.840 g / cm 3 above.

[0176] <11>

[0177] The porous film according to any one of <1> to <10>, wherein the olefinic resin composition comprises a low-melting-point olefinic resin having a melting point of less than 90° C.

[0178] The density of the low melting point olefin resin is 0.895 g / cm 3 Below, and

[0179] The density of the low melting point olefin resin is 0.840 g / cm 3 above.

[0180] <12>

[0181] The porous film as described in <11>, wherein the low-melting-point olefin-based resin is contained in an amount of 30 parts by mass to 95 parts by mass based on 100 parts by mass of the olefin-based resin composition.

[0182] <13>

[0183] The porous film according to any one of <1> to <12>, wherein the olefinic resin composition comprises a high-melting-point olefinic resin having a melting point of 95° C. or higher, and

[0184] The density of the high melting point olefin resin is 0.900 g / cm 3 Above and 0.950g / cm 3 the following.

[0185] <14>

[0186] The porous film as described in <13>, wherein the high melting point olefin-based resin contains polyethylene.

[0187] <15>

[0188] The porous film as described in <14>, wherein the high melting point olefin-based resin comprises linear low-density polyethylene.

[0189] <16>

[0190] The porous film according to <15>, wherein the linear low-density polyethylene comprises a linear low-density polyethylene polymerized with a metallocene catalyst.

[0191] <17>

[0192] The porous film as described in <11> or <12>, wherein the low-melting-point olefin-based resin comprises an ethylene-α-olefin copolymer.

[0193] <18>

[0194] The porous film according to <17>, wherein the ethylene-α-olefin copolymer comprises an ethylene-α-olefin copolymer polymerized with a metallocene catalyst.

[0195] <19>

[0196] The porous film according to any one of <1> to <10>, wherein the olefinic resin composition comprises a low-melting-point olefinic resin having a melting point of less than 90° C. and a high-melting-point olefinic resin having a melting point of 95° C. or higher.

[0197] The high melting point olefin resin comprises a linear low density polyethylene polymerized by a metallocene catalyst, and

[0198] The low-melting-point olefin-based resin includes an ethylene-α-olefin copolymer polymerized by a metallocene catalyst.

[0199] <20>

[0200] The porous membrane according to any one of <1> to <19>, further comprising an additive,

[0201] The additives include at least a first additive having an SP value that is less than 0.37 different from that of the triglyceride, and

[0202] The first additive is contained in an amount of 0.01 parts by mass or more and 3.5 parts by mass or less relative to 100 parts by mass of the total of the olefin-based resin composition, the inorganic filler, and the triglyceride.

[0203] <21>

[0204] The porous membrane according to any one of <1> to <20>, further comprising an additive,

[0205] The additive comprises at least a second additive having an SP value different from that of the triglyceride by 0.37 or more, and

[0206] The second additive is contained in an amount of 0.01 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the total of the olefin-based resin composition, the inorganic filler, and the triglyceride.

[0207] <22>

[0208] The porous membrane according to <21>, wherein the difference in SP value between the second additive and the triglyceride is 0.37 or more and 4.00 or less.

[0209] <23>

[0210] The porous film according to any one of <1> to <22>, wherein the average particle size of the inorganic filler is 30 μm or less.

[0211] <24>

[0212] The porous membrane according to any one of <1> to <23>, wherein calcium carbonate is used as the inorganic filler.

[0213] <25>

[0214] The porous film according to any one of <1> to <24>, comprising 60 parts by mass or more and 300 parts by mass or less of the inorganic filler based on 100 parts by mass of the olefin-based resin composition.

[0215] <26>

[0216] The porous film according to any one of <1> to <25>, wherein the amount of the triglyceride blended is 1.0 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the olefin-based resin composition.

[0217] <27>

[0218] The porous film according to any one of <1> to <26>, which is used for an absorbent article.

[0219] <28>

[0220] The porous film as described in <27> is used as a leakage-proof sheet in the absorbent article.

[0221] <29>

[0222] The porous film as described in <27> is used for the leak-proof cuffs in the absorbent article.

[0223] <30>

[0224] An absorbent article comprising the porous film according to any one of <1> to <29>.

[0225] <31>

[0226] The absorbent article as described in <30> above comprises a surface sheet forming a skin-facing surface, a leakage-proof sheet forming a non-skin-facing surface, and a liquid-retaining absorbent body disposed between the two sheets, and

[0227] The leakage-proof sheet is the porous film.

[0228] <32>

[0229] The absorbent article according to <30> comprises a surface sheet forming a skin-facing surface, a leakage-proof sheet forming a non-skin-facing surface, and a liquid-retaining absorbent body disposed between the two sheets.

[0230] Leak-proof cuffs are provided on both sides of the skin-facing surface along the length direction, and

[0231] The leak-proof flange is the porous membrane.

[0232] Example

[0233] The present invention will be described in more detail below with reference to Examples. However, the scope of the present invention is not limited to these Examples. Unless otherwise specified, "%" and "parts" refer to "mass %" and "mass parts".

[0234] [Reference Examples 1 to 15 and Comparative Reference Examples 1 to 8]

[0235] In this reference example and comparative reference example, a membrane containing triglyceride (non-porous membrane) was used as a test object, and the water resistance of triglyceride was evaluated by the following method. The results are shown in Tables 1 and 2 below.

[0236] (1) Manufacturing of composites

[0237] The components shown in Tables 1 and 2 below were weighed in the amounts shown in these tables, placed in a LaboPlastomill (manufactured by Toyo Seiki Co., Ltd.), and kneaded at 160° C. and 30 rpm for 10 minutes to obtain a composite.

[0238] The details of the components shown in Tables 1 and 2 are shown in Tables 3 and 4. In addition, the unit of the composition in Tables 1 and 2 is mass %.

[0239] (2) Film production

[0240] The composite was pressed at 150°C and 13 MPa for 1 minute using a Labo Press (manufactured by Toyo Seiki Co., Ltd.), then cooled and pressed at room temperature and 13 MPa for 1 minute to produce a film (resin sheet). The film thickness was adjusted to 0.5 mm.

[0241] (3) Evaluation of water resistance

[0242] The prepared membrane was immersed in 50 mL of toluene solution and then cleaned by wiping the membrane surface with toilet paper. The cleaned membrane was placed in an electric dryer and stored at 40°C for 7 days. After storage, the contact angle of the membrane surface, whose water repellency was adjusted by triglyceride exudation, was measured using a contact angle meter (DropMaster 500, manufactured by Kyowa Interface Science). Two evaluation solutions were used: one with a surface tension of 35.0 mN / m and one with a surface tension of 44.0 mN / m.

[0243] ·Determination method: drop method

[0244] Evaluation liquid: Mixed liquid for wetting tension test (surface tension at 25°C: 35.0 mN / m and 44.0 mN / m, manufactured by Kanto Chemical)

[0245] Droplet volume: 2μL

[0246] For each test piece, the contact angle was measured at five locations 10 seconds after the droplet landed, and the average value of the five drops was taken as the contact angle value.

[0247] [Table 1]

[0248]

[0249] [Table 2]

[0250]

[0251] The meanings of the letters in the Remarks column are shown in Table 4.

[0252] [Table 3]

[0253]

[0254] A: The difference in SP value with triglycerides B, E, and F is 0.37 or more; B: The difference in SP value with triglycerides B, E, and F is less than 0.37

[0255] [Table 4]

[0256]

[0257] From the results shown in Tables 1 and 2, it is understood that the contact angle of the films of the reference examples with the evaluation liquid is higher than that of the films of the comparative reference examples.

[0258] [Examples 1 to 8 and Comparative Examples 1 to 5]

[0259] (1) Manufacturing of composites

[0260] The components shown in Tables 5 and 6 below were weighed in the amounts shown. These were mixed using a Henschel mixer (manufactured by Kawada Co., Ltd.). The resulting mixture was kneaded using a twin-screw extruder (manufactured by Toyo Seiki Co., Ltd.) at a set temperature of 180°C and a screw speed of 180 rpm to obtain a pelletized composite. The units of composition in Tables 5 and 6 are expressed in mass %.

[0261] (2) Manufacturing of resin sheets

[0262] A resin sheet was formed from the composite using a 150 mm wide T-die (manufactured by Toyo Seiki Co., Ltd.) under the following molding conditions: a set temperature of 150° C. and a screw speed of 30 rpm.

[0263] (3) Production of porous membranes

[0264] The obtained resin sheet was uniaxially stretched using a tenter stretching machine (manufactured by IS Giken Co., Ltd.) to obtain a weight per unit area of ​​37 g / m 2 The stretching temperature and stretching ratio are shown in Tables 5 and 6.

[0265] [evaluate]

[0266] The water vapor permeability of the porous membranes obtained in Examples and Comparative Examples was measured by the following method. Furthermore, the degree of liquid permeation was evaluated by the following method. These results are shown in Tables 5 and 6.

[0267] [Moisture Permeability]

[0268] The water vapor permeability of the porous film is measured by the following method in accordance with JIS L 1099A-2 method.

[0269] Diameter 2.03cm (area 3.23cm 2 Approximately 25 mL of ion-exchanged water was added to a glass bottle (Laboran screw bottle No. 8, manufactured by AS ONE). A test piece was placed to cover the bottle mouth without any gaps and secured to the bottle with a rubber band to create an evaluation sample. After measuring the mass (W1) of the evaluation sample, the sample was stored in a thermostat controlled at 40°C and 20% RH for 10 to 15 hours. After storage, the mass (W2) of the evaluation sample was measured, and the storage time (T1, unit: h) was recorded. The moisture permeability was then calculated using the following formula (1).

[0270] Moisture permeability (g / (100cm 2 ·h))=(W1―W2) / (T1×3.23)×100(1)

[0271] The moisture permeability of the porous film of the present invention is preferably 0.65 g / (100 cm 2 h) or more, more preferably 0.70 g / (100 cm 2 ·h) or more, more preferably 0.75g / (100cm 2 ·h) or more. Thus, the porous film of the present invention has high moisture permeability, and can appropriately release the humidity inside the absorbent article to the outside. On the other hand, in order to avoid the loss of the leak-proofness required of the back sheet due to excessive porosity, the upper limit of the moisture permeability of the porous film is preferably 4.5g / (100cm 2 h) or less, more preferably 3.5 g / (100 cm 2 h) or less, more preferably 3.0 g / (100 cm 2 h) or below.

[0272] [Extent of fluid leakage]

[0273] A porous membrane cut to a size of 50 mm or more in the machine direction and 35 mm or more in the width direction was placed on a filter paper (Advantech Toyo Co., Ltd., No. 2, 70 mm in diameter). A dry pulp sheet (Reed Healthy Cooking Paper Double, Lion Co., Ltd., with a basis weight of 40 g / m2) was placed on the porous membrane. 2 ) cut into 25mm×30mm.

[0274] 0.265 g of a wetting tension test solution (surface tension at 25°C: 35 mN / m, manufactured by Kanto Chemical) was injected into the center of the dry pulp sheet using a dropper. After injection, a cylindrical acrylic plate with a diameter of 60 mm and a thickness of 5 mm was placed on top, and a 500 g weight was placed on top. Pressure was applied for up to 60 minutes.

[0275] After 20 minutes and 60 minutes, the weight was removed and the extent of liquid seeping onto the filter paper was visually observed to determine whether there was seepage. This evaluation was performed for three groups at each level, and the extent of seepage was evaluated based on the following criteria.

[0276] A: No bleeding was observed on any of the three filter papers after 60 minutes.

[0277] B: No bleeding was observed on any of the three filter papers after 20 minutes.

[0278] C: Bleeding was observed in at least one tablet after 20 minutes.

[0279] [Table 5]

[0280]

[0281] The meanings of the letters in the Remarks column are shown in Table 4.

[0282] [Table 6]

[0283]

[0284] The meanings of the letters in the Remarks column are shown in Table 4.

[0285] From the results shown in Tables 5 and 6, it can be seen that the porous membrane obtained in each Example maintains high moisture permeability and has high liquid seepage prevention performance.

[0286] [Comparative Example 6]

[0287] A porous membrane was produced in the same manner as in Example 1 except that the components shown in Table 7 below were used, and the following evaluations were performed. Note that Example 4 is shown again in Table 7.

[0288] [evaluate]

[0289] Two porous films were stacked and pressed using a Labo Press (manufactured by Toyo Seiki Co., Ltd.) at 50°C and 127 MPa for 1 minute. The films were then cooled at room temperature for 5 minutes to prepare samples for blocking evaluation. Blocking was evaluated by manually peeling the two films from the prepared evaluation samples to confirm the presence of blocking. This evaluation was performed for three groups at each level, and blocking was evaluated based on the following criteria.

[0290] A: All three sheets peeled off easily by hand.

[0291] B: When peeled off by hand, at least one piece is difficult to peel off and the film is broken.

[0292] [Table 7]

[0293]

[0294] The meanings of the letters in the Remarks column are shown in Table 4.

[0295] From the results shown in Table 7, it can be seen that the porous membrane obtained in Example 4 is less likely to cause blocking than that in Comparative Example 6.

[0296] Industrial applicability

[0297] As described above in detail, according to the present invention, there is provided a porous membrane having higher leakage prevention properties than conventional ones while maintaining satisfactory moisture permeability.

Claims

1. A porous film comprising at least an olefin resin composition, an inorganic filler and a triglyceride, The filler is contained in an amount of 50 parts by mass or more and 400 parts by mass or less, and the triglyceride is contained in an amount of 0.1 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the olefin resin composition. The triglycerides are: (A) a mixture of a triglyceride containing in one molecule at least a group derived from a fatty acid having 18 carbon atoms and a triglyceride containing in one molecule at least a group derived from a fatty acid having 16 to 22 carbon atoms other than a fatty acid having 18 carbon atoms; or (B) a triglyceride containing in one molecule at least one group derived from a saturated fatty acid having 18 carbon atoms and at least one group derived from a saturated fatty acid having 16 to 22 carbon atoms other than a fatty acid having 18 carbon atoms, The group derived from the fatty acid having 16 to 22 carbon atoms contained in the triglyceride is a hydrocarbon group having no unsaturated bond and no substituent.

2. The porous membrane according to claim 1, wherein The triglyceride is a triglyceride containing at least one group derived from a saturated fatty acid having 18 carbon atoms and at least one group derived from a saturated fatty acid having 16 to 22 carbon atoms other than the fatty acid having 18 carbon atoms in one molecule.

3. The porous membrane according to claim 1 or 2, wherein With respect to the total amount of the fatty acid-derived groups contained in all triglycerides, 28% by mass or more and 96% by mass or less are groups derived from a fatty acid having 18 carbon atoms. The porous membrane according to claim 1 , wherein With respect to the total amount of the fatty acid-derived groups contained in all triglycerides, 28% by mass or more and 70% by mass or less are groups derived from a fatty acid having 18 carbon atoms. The porous membrane according to claim 1 , wherein With respect to the total amount of the fatty acid-derived groups contained in all triglycerides, 28% by mass or more and 68% by mass or less are groups derived from fatty acids having 18 carbon atoms, and 26% by mass or more and 70% by mass or less are groups derived from fatty acids having 16 carbon atoms. The porous membrane according to claim 1 , wherein With respect to the total amount of the fatty acid-derived groups contained in all triglycerides, 28% by mass or more and 47% by mass or less are groups derived from fatty acids having 18 carbon atoms, and 40% by mass or more and 60% by mass or less are groups derived from fatty acids having 22 carbon atoms.

7. The porous membrane according to claim 1, wherein The fatty acid-derived groups contained in all triglycerides are hydrocarbon groups having no unsaturated bonds. The porous membrane according to claim 1 , wherein The fatty acid-derived groups contained in all triglycerides are hydrocarbon groups having no substituent.

9. The porous membrane according to claim 1, wherein The density of the olefin resin composition is less than 0.900 g / cm 3 ,and The density of the olefin resin composition is 0.840 g / cm 3 above.

10. The porous membrane according to claim 1, wherein The olefin resin composition comprises a low-melting-point olefin resin having a melting point of less than 90° C. The density of the low melting point olefin resin is 0.895 g / cm 3 Below, and The density of the low melting point olefin resin is 0.840 g / cm 3 above. The porous membrane according to claim 10 , wherein The low-melting-point olefin-based resin is contained in an amount of 30 parts by mass or more and 95 parts by mass or less per 100 parts by mass of the olefin-based resin composition.

12. The porous membrane according to claim 1, wherein The olefin resin composition comprises a high melting point olefin resin having a melting point of 95° C. or higher, and The density of the high melting point olefin resin is 0.900 g / cm 3 Above 0.950 g / cm 3 the following.

13. The porous membrane according to claim 12, wherein The high melting point olefin-based resin includes polyethylene. The porous membrane according to claim 13 , wherein The high melting point olefin resin includes linear low-density polyethylene. The porous membrane according to claim 14 , wherein The linear low-density polyethylene includes linear low-density polyethylene polymerized by a metallocene catalyst. The porous membrane according to claim 10 , wherein The low-melting-point olefin-based resin includes an ethylene-α-olefin copolymer.

17. The porous membrane according to claim 16, wherein The ethylene-α-olefin copolymer includes an ethylene-α-olefin copolymer polymerized by a metallocene catalyst. The porous membrane according to claim 1 , wherein The olefin resin composition comprises a low-melting-point olefin resin having a melting point of less than 90° C. and a high-melting-point olefin resin having a melting point of 95° C. or higher. The high melting point olefin resin comprises a linear low density polyethylene polymerized by a metallocene catalyst, and The low-melting-point olefin-based resin includes an ethylene-α-olefin copolymer polymerized by a metallocene catalyst.

19. The porous membrane according to claim 1, further comprising an additive, The additives include at least a first additive having an SP value that is less than 0.37 different from that of the triglyceride, and The first additive is contained in an amount of 0.01 parts by mass or more and 3.5 parts by mass or less relative to 100 parts by mass of the total of the olefin-based resin composition, the inorganic filler, and the triglyceride.

20. The porous membrane according to claim 1, further comprising an additive, The additive comprises at least a second additive having an SP value different from that of the triglyceride by 0.37 or more, and The second additive is contained in an amount of 0.01 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the total of the olefin-based resin composition, the inorganic filler, and the triglyceride.

21. The porous membrane according to claim 20, wherein The difference in SP value between the second additive and the triglyceride is 0.37 or more and 4.00 or less.

22. The porous membrane according to claim 1, wherein The average particle size of the inorganic filler is 30 μm or less.

23. The porous membrane according to claim 1, wherein Calcium carbonate was used as the inorganic filler.

24. The porous membrane according to claim 1, wherein The inorganic filler is contained in an amount of 60 parts by mass or more and 300 parts by mass or less based on 100 parts by mass of the olefin-based resin composition.

25. The porous membrane according to claim 1, wherein The amount of the triglyceride blended is 1.0 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the olefin-based resin composition. The porous film according to claim 1 , which is used for an absorbent article. The porous film according to claim 26, which is used as a leakage-proof sheet in the absorbent article. The porous film according to claim 26 , which is used for leak-proof cuffs in the absorbent article. An absorbent article comprising the porous film according to claim 1.

30. The absorbent article according to claim 29, comprising a surface sheet forming a skin-facing surface, a leakage-proof sheet forming a non-skin-facing surface, and a liquid-retaining absorbent body disposed between the two sheets, The leakage-proof sheet is the porous film.

31. The absorbent article according to claim 29, comprising a surface sheet forming a skin-facing surface, a leakage-proof sheet forming a non-skin-facing surface, and a liquid-retaining absorbent body disposed between the two sheets. Leak-proof cuffs are provided on both sides of the skin-facing surface along the length direction, and The leak-proof flange is the porous membrane.

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