JP2001293826A - Laminated porous film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated porous film excellent in air permeability, flexibility, barrier propertries or the like. SOLUTION: The laminated porous film, which is obtained by molding a composition containing a polyolefin resin, a filler and a third component in a molten state to form a film and stretching the film, consists of an X-layer containing an amide compound as the third component and a Y-layer containing at least one of an ester compound, a hydrocarbon polymer having a side chain, a silicone polymer and mineral oil as the third component and a thickness ratio of the X-layer and the Y-layer is 1/10-10/1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous film used for sanitary materials, medical materials, architectural materials and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a porous film, a method in which a raw material composition containing a polyolefin resin and a filler is melt-molded to generate a film and a void is generally used. When used as a material for disposable diapers and sanitary products, it is particularly required that it does not leak human urine, blood, etc. and that it can only pass moisture. Moreover, it is difficult to obtain a material having a supple feel from a raw material composition comprising only a polyolefin resin and a filler. Therefore, in order to improve the performance of the porous film, many methods have been proposed in which a raw material composition is blended with a third component other than a polyolefin resin and a filler. As the third component, hardened castor oil (Japanese Patent Application Laid-Open No. Hei 4-227538), dehydrated castor oil (Japanese Patent Application Laid-Open No. 9-208730), a mixture of hardened castor oil + dehydrated castor oil (Japanese Patent Application Laid-Open No. 9-221560), liquid polybutadiene, liquid polybutene, Hydroxy-terminated polybutadiene (JP-A-58-15538) and liquid polyisoprene (JP-A-58-149925) are known.

[0003]

There are other problems with the porous film. For example, in use, it is necessary that the adhesive tape such as a fastening tape has good adhesion to the film. When a porous film with poor adhesion is used as a backsheet for disposable diapers, it is difficult to fix the disposable diaper with fastening tape when attaching it to the human body, which may cause leakage of human urine etc. Become. Furthermore, at that time, there is a problem that the components contained in the adhesive tape migrate to the porous film, the shielding property is impaired, and the opaque part is transparent and the inside can be seen through. However, with the above-mentioned known method, there has been no method capable of simultaneously solving the above-mentioned problems of adhesiveness and shielding while maintaining sufficient air permeability.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have maintained the air permeability at the same level or higher as that of conventional products.
As a result of intensive studies to provide a porous film that has excellent adhesion and shielding properties, and is flexible and has a good texture, a film layer using a raw material composition containing a specific third component is combined. It has been found that a porous film having desired physical properties can be obtained by using such a laminated film, and the present invention has been achieved. That is, the present invention is a porous film obtained by melt-forming a composition containing a polyolefin resin, a filler and a third component to form a film, and then subjecting the film to a stretching treatment, wherein the third component is X containing hardened castor oil
And a Y layer containing at least one of an ester compound, a hydrocarbon polymer having a side chain, a silicone polymer, and a mineral oil as the third component. The thickness ratio of the X layer and the Y layer is 1/10 to 10: 10/1, which is a laminated porous film.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As the polyolefin resin used in the present invention, ethylene, propylene, and those mainly containing a monoolefin polymer and copolymer such as butene, for example, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene , Ethylene propylene random or block copolymer, polybutene, ethylene vinyl acetate copolymer and mixtures thereof. Among them, linear low-density polyethylene is preferred because it is flexible and tough.

The polyolefin resin used in the present invention is
And particularly preferred are linear density polyethylene and branched low-density polyethylene.
It is a mixture of high density polyethylene. Linear low density polyethylene
Ren is an α-olefin having a molecular skeleton having 3 to 8 carbon atoms.
It is a copolymer of ethylene and ethylene. Linear low density polyethylene
Len has a density of 0.910 to 0.940 g / cm
^ThreeHaving a melt index of 0.5 to 5 g / 10 minutes
Is preferred. Density 0.910g / cm^ThreeLess than
Uniform stretchability decreases, 0.940 g / cm^ThreeExceeds
The softness of the stretched film is impaired. Also, Mel Toy
When the index is less than 0.5 g / 10 minutes, the film
A film with a uniform thickness due to abnormal flow during extrusion
It is difficult to obtain.
Elongation deteriorates.

[0007] The branched low-density polyethylene is obtained by polymerizing ethylene by a known high-pressure method, and has a melt index of 0.1 to 2 g / 10 min.
Those having a density of 0.915 to 0.925 g / cm ³ are preferred. When the melt index is less than 0.1 g / 10 minutes, the mixing with the former linear low-density polyethylene is poor, and when it exceeds 2 g / 10 minutes, a film having a uniform thickness cannot be obtained. If the density exceeds 0.925, it becomes difficult to obtain a film having a uniform thickness.

[0008] The mixing ratio of the polyethylene resin in the above, linear low density polyethylene is usually 75 to 98
%, Preferably 85 to 96% by weight, and the branched low density polyethylene is usually 25 to 2% by weight, preferably 15 to 96% by weight.
4% by weight. If the amount of the branched low-density polyethylene exceeds 25% by weight, the elongation of the film in a molten state is reduced, and it is difficult to process the film. On the other hand, if it is less than 2% by weight, it is difficult to obtain a film having a uniform thickness.

Next, examples of the filler include calcium carbonate, barium sulfate, calcium sulfate, barium carbonate, magnesium hydroxide, aluminum hydroxide, zinc oxide, magnesium oxide, titanium oxide, silica, and talc. Of these, calcium carbonate and barium sulfate are particularly preferred. The average particle size of such a filler is usually 20 μm or less, preferably 10 μm or less, particularly preferably 0.5 to 5 μm. The filler is desirably coated with a surface treating agent to make the surface of the filler hydrophobic to improve dispersibility in the resin. Examples of such a surface treating agent include stearic acid and lauric acid. And higher metal salts thereof and metal salts thereof.

[0010] The laminated porous film of the present invention comprises a resin composition containing the above polyolefin resin and a filler,
Resin compound (X) with hardened castor oil added as third component
And an X layer and a Y layer using a resin composition (Y) to which at least one of an ester compound, a hydrocarbon polymer having a side chain, a silicone polymer, and a mineral oil is added as a third component. Things. In the present invention, hydrogenated castor oil is a hydrogenated double bond of ricinoleic acid,
An ester of glycerin with a fatty acid mixture containing 12-hydroxyoctadecanoic acid as a saturated fatty acid as a main component. The ester includes a monoester, a diester and a triester. These may be used alone or in a mixture, but those containing a triester as a main component are preferable. The content of 12-hydroxyoctadecanoic acid in the fatty acid mixture was 70% by weight.
Thus, the number of carbon atoms of hexadecanoic acid, octadecanoic acid, etc.
By setting the content of other fatty acids of about 2 to 22 to less than 30% by weight, the shielding property of the porous film surface can be prevented from decreasing with time. Such hydrogenated castor oil is industrially produced by hydrogenating castor oil, which is a non-drying oil, and commercially available products include, for example, Ito Oil Co., Ltd., hydrogenated castor oil, trade name: Custer wax, etc. Can be mentioned.

The ester compound is not particularly limited as long as it is a monoester or polyester having a structure composed of an alcohol and a carboxylic acid, but is preferably a compound blocked in the form of an ester group, such as stearyl stearate or sorbitan tristearate. Rate, epoxy soybean oil, refined castor oil, dehydrated castor oil, epoxy soybean oil, extremely hardened oil, trioctyl trimellitate, ethylene glycol dioctanoate, pentaerythritol tetraoctanoate, and the like. The hydrocarbon polymer having a side chain is preferably a poly-α-olefin having an oligomer region having a side chain having 4 or more carbon atoms, but an ethylene-propylene copolymer, for example, Mitsui Petrochemical Industry Co., Ltd. ) Manufactured by Lucent or its maleic acid derivative, a polymer of isobutylene, for example, polybutene HV-100 manufactured by Idemitsu Petrochemical Industry Co., Ltd., or an oligomer of butadiene, isoprene and its hydrogenated product or a derivative thereof. There may be. Any known silicone oil may be used, and examples thereof include polydimethylsiloxane and polymethylphenylsiloxane. Examples of the mineral oil include liquid paraffin and paraffin wax.

In the laminated porous film of the present invention, X
The thickness ratio between the layer and the Y layer is 1/10 to 10/1. The X layer alone is excellent in shielding properties but not enough in flexibility.
There is a problem that the shielding property tends to be insufficient with only the layer, and the layer ratio is not stable when the thickness ratio is out of the range, and it is difficult to perform uniform stretching. Then, by laminating the X layer and the Y layer in an appropriate range, well-balanced film properties can be exhibited. As the layer structure, X /
Y, X / Y / X, Y / X / Y, Y / X / Y ', X / Y /
X / Y / X, X / Y / X / Y '/ X, X / Y / X / Y'
And the like, but the configuration of X / Y and X / Y / X is preferable from the viewpoint of productivity. The thickness of such a laminated porous film is usually about 10 to 100 μm. 10
If it is less than μm, the film is easily broken, and if it exceeds 100 μm, the film becomes hard, and it is difficult to obtain a porous film having a cloth-like soft feeling and good texture, which is not preferable.

The laminated porous film of the present invention is produced from the resin compositions X and Y containing the above polyolefin resin, filler and specific third component. As the composition of the resin composition in this case, the polyolefin resin is usually 25 to
For 50 parts by weight, preferably 35 to 45 parts by weight, the filler is in the range of 75 to 50 parts by weight, preferably 65 to 55 parts by weight. If the amount of the filler is less than 50 parts by weight, adjacent voids formed by peeling off the interface between the polyolefin resin and the filler will not communicate with each other, and it will be difficult to obtain air permeability. On the other hand, if it exceeds 75 parts by weight, elongation during stretching of the film is lost, and stretching becomes difficult.

The addition of the third component to the resin composition is as follows:
Film thickness uniformity, stretchability, film texture,
This has a significant effect on film formability, film adhesion, and the like. If the added amount is too large, these bleed out from the film, and the adhesiveness is deteriorated. On the other hand, if the addition amount is too small, the film becomes hard and the texture deteriorates,
Thickness uniformity also worsens. Considering this point, the total amount of the third component is preferably 0.5 to 5 parts by weight based on 100 parts by weight of the total amount of the polyolefin resin and the inorganic filler. In addition, in the resin composition, in addition to the above essential components, additives generally used for resin compositions,
For example, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, neutralizers, antifogging agents, antiblocking agents, antistatic agents, slip agents, coloring agents, etc., do not impair the properties of the porous film. You may mix | blend in the range of a degree.

The laminated porous film of the present invention is obtained by mixing the above resin composition with a Henschel mixer, a super mixer, a tumbler type mixer or the like, and then kneading the mixture with a single-screw or twin-screw extruder, a kneader, or the like, and pelletizing the mixture. Become Then, the pellets are molded at a temperature equal to or higher than the melting point of the polyethylene resin, preferably equal to or higher than the melting point + 20 ° C. and lower than the decomposition temperature, by a known molding method such as an extruder equipped with a T-die or the like or an inflation molding machine equipped with a circular die. Melting and film formation using a machine. In some cases, the film can be directly formed by a molding machine without pelletizing. And X
The layer and the Y layer may be separately formed and then subjected to thermocompression bonding, or may be formed into a multilayer by extrusion lamination between the two layers.

The formed film is formed at room temperature to the softening point (JI) of the resin by a known method such as a roll method or a tenter method.
(Measured value according to SK6760), stretching is performed at least in a uniaxial direction to cause interfacial separation between the polyolefin resin and the inorganic filler to obtain a porous film. Stretching may be performed in one step or in multiple steps. Further, since the stretching ratio relates to tearing of the film during stretching, air permeability of the obtained film, softness of the film, and the like, it is not preferable that the ratio is too high or too low. From such a viewpoint, the stretching ratio in the present invention is usually 1.2 to 5 times, preferably 1.5 to 3 times. When biaxially stretching, first uniaxially stretching in the machine direction or in a direction perpendicular to it, then a method of stretching the second axis in a direction perpendicular to this direction, and machine direction, and perpendicular to it And simultaneously biaxially stretching in the direction of After the stretching, a heat setting treatment may be performed, if necessary, in order to stabilize the form of the obtained opening.

Hereinafter, the present invention will be described more specifically by way of examples. In addition, the evaluation method performed in the Example is as follows. (1) Air permeability Measured according to JIS-P8117 (unit: sec / 5
0cc). (2) Stretchability The uniform stretchability of the stretched film was visually evaluated according to the following criteria. ：: Stretching unevenness was hardly recognized. Δ: Stretching unevenness was observed. X: Stretching unevenness was significantly observed.

(3) Flexibility Evaluation was made according to the following criteria by touch feeling. ：: No rustling sound even when the film was bent, and the feel was very good. ：: No rustling sound even when the film was bent, and the feel was good. Δ: The film does not make a rustling sound even when bent, but is slightly hard and uncomfortable. ×: A crunchy sound was produced even when the film was bent, and the film was hard and uncomfortable.

(4) Shielding property One side of a double-sided adhesive tape (trade name: KOKUYO T-225) having a width of 25 mm was adhered to one surface of the film to prepare a sample, and the remaining release paper was peeled off to obtain a total light transmittance of T1. It was measured. Also, one side of a double-sided adhesive tape having a width of 25 mm (trade name: KOKUYO T-225) was adhered to one surface of the film to form a sample. The sample was left in a constant temperature and humidity of 40 ° C. and 75% for one week, and then left at room temperature. The sample was peeled off and the remaining release paper was peeled off, and the total light transmittance of the sample was measured as T2. Then, the difference in total light transmittance (T (%) = T1−T2 (%)) was measured and evaluated according to the following criteria. ：: T is less than 10% ：: T is 10% or more and less than 20% Δ: T is 20% or more and less than 30% ×: T is 30% or more The measurement of total light transmittance was based on JIS-K6718. Haze meter (NDH-20 manufactured by Nippon Denshoku Co., Ltd.)
0) was used.

Examples 1 to 6, Comparative Examples 1 to 10 (X) Raw material: linear low-density polyethylene [manufactured by Nippon Polychem Co., Ltd., trade name: F in 38 parts by weight of polyethylene resin]
W20G, density: 0.921 g / cm ³ , MI: 1 g /
10 minutes] to 32 parts by weight (95% by weight in polyethylene resin) of branched low-density polyethylene [manufactured by Nippon Polychem Co., Ltd., trade name: LF441, density: 0.919 g /
cm ³ , MI: 2 g / 10 min], 5 parts by weight, 62 parts by weight of calcium carbonate (average particle size 1.2 μm, fatty acid treatment), and the third component shown in Table 1 were mixed with a tumbler mixer, and then mixed in a tandem type. The mixture was uniformly kneaded at 220 ° C. using a kneading extruder and processed into pellets. (Y) Raw material: Linear low-density polyethylene [manufactured by Nippon Polychem Co., Ltd., trade name: F in 37 parts by weight of polyethylene resin]
W20G, density: 0.921 g / cm ³ , MI: 1 g /
10 minutes] to 32 parts by weight (95% by weight in polyethylene resin) of branched low-density polyethylene [manufactured by Nippon Polychem Co., Ltd., trade name: LF441, density: 0.919 g /
cm ³ , MI: 2 g / 10 min], 5 parts by weight, 63 parts by weight of calcium carbonate (average particle diameter 1.2 μm, fatty acid treatment), and the third component shown in Table 1 were mixed with a tumbler mixer, and then mixed in a tandem type. The mixture was uniformly kneaded at 220 ° C. using a kneading extruder and processed into pellets. Using an extruder equipped with a multilayer circular die, the above pellets were treated at 200 ° C. in two layers of X / Y (layer ratio 5/5).
5) After the melt film formation, a preheating roll heated to 60 ° C. and a stretching roll were used at a stretching ratio of 2.0 times and a line speed of 2 mm.
The film was uniaxially stretched in the machine direction at 0 m / min to obtain a porous film having a thickness of 25 μm. Table 2 shows properties of the obtained porous film. Comparative Example 8 refers to a 25 μm-thick single-layer porous film made of a composition using a hardened castor oil as the third component.

Example 7, Comparative Example 11 (X) Raw material: Linear low-density polyethylene [manufactured by Nippon Polychem Co., Ltd., trade name: F in 37 parts by weight of polyethylene resin]
W20G, density: 0.921 g / cm ³ , MI: 1 g /
10 minutes] to 32 parts by weight (95% by weight in polyethylene resin) of branched low-density polyethylene [manufactured by Nippon Polychem Co., Ltd., trade name: LF441, density: 0.919 g /
cm ³ , MI: 2 g / 10 min], 63 parts by weight of calcium carbonate (average particle size 1.2 μm, fatty acid treatment),
After mixing the third component shown in Table 1 with a tumbler mixer, the mixture was uniformly kneaded at 220 ° C. using a tandem kneading extruder and processed into pellets. (Y) Raw material: Linear low-density polyethylene [manufactured by Nippon Polychem Co., Ltd., trade name: F in 37 parts by weight of polyethylene resin]
W20G, density: 0.921 g / cm ³ , MI: 1 g /
10 minutes] to 32 parts by weight (95% by weight in polyethylene resin) of branched low-density polyethylene [manufactured by Nippon Polychem Co., Ltd., trade name: LF441, density: 0.919 g /
cm ³ , MI: 2 g / 10 min], 63 parts by weight of calcium carbonate (average particle size 1.2 μm, fatty acid treatment),
After mixing 1 part by weight of the third component shown in Table 1, using a tumbler mixer, the mixture was heated to 220 ° C. using a tandem kneading extruder.
And uniformly kneaded, and processed into pellets. The pellets were prepared using an extruder equipped with a multilayer T-die,
After forming a melt film in three layers of X / Y / X (layer ratio 2/6/2) at a temperature of 60 ° C., a line speed at a draw ratio of 2.1 times between a preheating roll and a drawing roll heated to 60 ° C. The film was uniaxially stretched in the machine direction at 20 m / min to obtain a porous film having a thickness of 25 μm. Table 2 shows the obtained physical properties.

[0022]

[Table 1]

The third component in Table 1 is as follows. Hardened castor oil: manufactured by Ito Oil Co., Ltd. Hardened castor oil Castor wax Dehydrated castor oil: manufactured by Ito Oil Co., Ltd. Product name: Dehydrated castor oil DCO Refined castor oil: manufactured by Ito Oil Co., Ltd. Refined castor oil LAV EBS: Nippon Chemical Co., Ltd. Product name Ethylenebisstearic acid amide Sribakx E DEA: Condensate produced by dehydration reaction of adipic acid and diethylene glycol at a molar ratio of 3: 2 Epoxy soybean oil: Product name Adekasizer O-13- manufactured by Asahi Denka Kogyo Co., Ltd. P DPEHO: Mitsubishi Chemical Co., Ltd. Product name Dipentaerythritol Exaoctanoate D-600 PHA: Mitsubishi Chemical Co., Ltd. Product name: Polytail HA PB: Nippon Yushi Co., Ltd. Product name: Nissan Polybutene 200SH Silicone Oil : Toshiba Silicone Product Name Dimethyl Silicone TS -451 pentaerythritol exercise octanoate D-600 TTO: Mitsubishi Chemical Corporation, trade name: trimellitic acid trioctyl D-1174

[0024]

[Table 2]

[0025]

Industrial Applicability The laminated porous film of the present invention has good adhesiveness and shielding properties while maintaining air permeability, uniform stretchability, and the like at or above the level of the conventional product, and has high flexibility. The texture is good. Therefore, sanitary materials such as disposable paper diapers, body fluid absorbing pads, bed sheets, etc., medical materials such as surgical gowns, base materials for hot compresses, clothing materials such as jumpers and rainwear, wallpaper, roof waterproof materials, etc. It can be very suitably used as a packaging material such as a material for use, a desiccant, a desiccant, an oxygen scavenger, a disposable body warmer, a packaging for keeping freshness, a food packaging, and a separator for a battery.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C08L 23/00 C08L 23/00 83/04 83/04 91/00 91/00 F term (reference) 4F074 AA16 AA17 AA26 AA64 AA90 AA98 AC26 AD11 AD13 AG01 CA02 CA05 CA06 DA10 DA17 DA23 DA53 4F100 AA08H AH02A AH02B AH02C AH02H AK03A AK03B AK03C AK04 AK06 AK08B AK08C AK08B30A23 BA03 BA03 BA03 BA03 BA03 BA03 BA03 BA03 BA23 EJ37 GB07 GB15 GB23 GB66 GB72 JD02 JK06 JK13 JK17 4J002 AE043 AE053 BB03W BB03X BB04W BB04X BB06W BB06X BB12W BB12X BB14W BB14X BB15W BB15X BB153 BB17W BB17X BB173 BL013 BL023 BP02W BP02X CD163 CP033 DE076 DE106 DE136 DE146 DE236 DG046 DG056 DJ016 DJ046 EA017 EH047 FB236 FD016 GB00 GF00 GL00

Claims (2)

[Claims] 1. A porous film obtained by melt-forming a composition containing a polyolefin resin, a filler and a third component to form a film, and then subjecting the film to a stretching treatment, wherein the film is cured as the third component. An X layer containing castor oil, and a Y layer containing at least one of an ester compound, a hydrocarbon polymer having a side chain, a silicone polymer, and a mineral oil as the third component, wherein the thickness ratio of the X layer and the Y layer is 1/10
A laminated porous film, wherein the ratio is from 10/1 to 10/1. 2. A multi-layer structure of X / Y, X / Y / X, Y / X
/ Y. The laminated porous film of claim 1, wherein