JPH032893B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a porous film or sheet. Specifically, the present invention relates to a method for producing a porous film or sheet from a composition obtained by blending a filler and a polyhydroxy saturated hydrocarbon with a polyolefin resin. Conventionally, many attempts have been made to uniaxially or biaxially stretch a film or sheet obtained by blending a filler into a polyolefin resin and melt-molding it as a means of producing a porous film. However, in these films, problems remain in the anisotropy of the film physical properties, especially the tear resistance and surface strength in the longitudinal direction (stretching direction), in the case of uniaxially oriented products, or in the film physical properties in the biaxially oriented products. Although there is no problem with anisotropy, there are problems with surface strength and stretchability, and both tend to have high overall rigidity, which may be a drawback depending on the application. One way to improve the anisotropy and surface strength of the film is to stretch it at as low a magnification as possible to make it porous, but satisfactory results have not yet been obtained. Additionally, adding low-melting point polymers, rubber-like substances, plasticizers, surfactants, etc. can be considered as a method of imparting flexibility to the film, but the balance between physical properties such as porosity, stretchability, and surface strength can be considered. I have not yet found anything that satisfies this. The present inventors have thus improved the drawbacks of conventional porous films or sheets, and have achieved a good balance of physical properties between tear strength and moisture permeability in uniaxial stretching, and high surface strength, and high surface strength and high surface strength in biaxial stretching. The present invention was arrived at as a result of intensive studies aimed at providing a porous film or sheet that is both highly stretchable and highly flexible. That is, the gist of the present invention is to blend a polyolefin resin with a filler and a polyhydroxy saturated hydrocarbon whose main chain is saturated or mostly saturated and has at least 1.5 hydroxyl groups per molecule, which is obtained by hydrogenating liquid polybutadiene. The present invention relates to a method for producing a porous film or sheet, which comprises stretching a film or sheet obtained by melt-molding a composition comprising: Hereinafter, the present invention will be explained in more detail. The polyolefin resin used in the present invention includes high-density polyethylene, polypropylene, and other α
- Copolymers with olefins, etc. alone and
It is also used as a mixture of more than one species. Among them,
High-density polyethylene and polypropylene alone are preferably used, and high-density polyethylene is particularly preferred. Inorganic and organic fillers are used as fillers, and inorganic fillers include calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, and water. Aluminum oxide, zinc oxide, magnesium hydroxide, calcium oxide, magnesium oxide, titanium oxide, alumina, mica, asbestos powder, glass powder, shirasu balloon, zeolite, clay silicate, etc. are used, especially calcium carbonate, talc, clay, and silica. , diatomaceous earth, barium sulfate, etc. are suitable. As the organic filler, cellulose powder such as wood flour and pulp powder is used. These may be used alone or in combination. The average particle size of the filler is preferably 30 μ or less, more preferably 10 μ or less, and 1 to 1 μm.
5μ is most preferred. If the particle size is too large, the density of the pores in the drawn product will be poor, and if the particle size is too small, the dispersibility in the resin will be poor and the moldability will be poor. Surface treatment of the filler is preferably carried out in terms of dispersibility in the resin and further stretchability, and treatment with a fatty acid or a metal salt thereof gives preferable results. The polyhydroxy saturated hydrocarbon used in the present invention is a main chain saturated or mostly saturated hydrocarbon polymer having at least 1.5 hydroxyl groups per molecule, 400 to 48,000, preferably 500 to 20,000. Those having a number average molecular weight (based on the vapor pressure method) in the range of are used. If the number average molecular weight is too small, the weather resistance will not be sufficient, and if it is too large, the fluidity will decrease, making handling difficult. The average number of hydroxyl groups per molecule is 1.5 or more, preferably 1.8 or more, and particularly preferably 2.0 to 5.0. The hydroxyl group is preferably located at the end of the main chain or at the end of a long chain branch. However, such polyhydroxy saturated hydrocarbons can be obtained by hydrogenating a butadiene-based liquid polymer obtained by radical polymerization of butadiene alone or with a copolymerizable monomer using a known method such as hydrogen peroxide as a polymerization initiator. obtained by Examples of copolymerizable monomers include isoprene, chloroprene, styrene, methyl (meth)acrylate, and methyl vinyl ether. Hydrogenation is carried out in a conventional manner using a nickel catalyst (eg reduced nickel, Raney nickel), cobalt catalyst, platinum catalyst, palladium catalyst, rhodium catalyst, ruthenium catalyst, or a mixture or alloy catalyst thereof. It is presumed that the introduction of a material having a polar group at the terminal into the polyolefin resin and filler system will give preferable results in improving the compatibility between the two. By using such a polyhydroxy saturated hydrocarbon, the dispersibility of the filler and the resulting film are improved, compared to the case where, for example, liquid polybutadiene, liquid polybutene, and unsaturated hydroxy hydrocarbons having hydroxyl groups at their end groups are used. Alternatively, the tear resistance, weather resistance, and heat resistance of the sheet are significantly improved. Note that heat and ultraviolet stabilizers, pigments, antistatic agents, fluorescent agents, and the like may be added to the polyolefin resin according to conventional methods. When blending polyolefin resin, filler, and polyhydroxy saturated hydrocarbon, the blending ratio is 25 parts by weight of filler per 100 parts by weight of polyolefin resin.
~400 parts by weight, 1~ polyhydroxy saturated hydrocarbon
100 parts by weight is preferred. The percentage of filler. If the amount is less than 25 parts by weight, sufficient pores will not be formed in the stretched film, resulting in a low degree of porosity. If the proportion of the filler exceeds 400 parts by weight, the kneading properties, dispersibility, film or sheet formability will be poor, and the surface strength of the stretched product will be reduced. In the present invention, a particularly preferred blending ratio is 60 to 60 parts by weight of filler to 100 parts by weight of polyolefin resin.
It is 200 parts by weight. Regarding the blending ratio of polyhydroxy saturated hydrocarbon, if it exceeds 100 parts by weight, the properties of the polyolefin resin will be weakened, and satisfactory kneading properties, film or sheet formability, and stretchability cannot be ensured. In the present invention, a more preferable blending ratio is 5 to
The amount is 50 parts by weight, more preferably 10 to 40 parts by weight. The polyolefin resin, filler, and polyhydroxy saturated hydrocarbon can be blended by placing the three in a normal blender or mixer, but preferably the following method is used to improve mixability, filler dispersibility, and Good in terms of film or sheet formability. The polyolefin resin is preferably in the form of a powder, and one with a mesh size of 10 to 150 is usually used, but one with a mesh size of 30 to 80 is more preferable in terms of uniformity and handling. As the mixer, a drum, a tumbler type mixer, a ribbon blender, a Henschel mixer, a super mixer, etc. are used, and a high-speed stirring type mixer such as a Henschel mixer is preferable. As for the mixing order, the polyolefin resin powder is first put into these mixers, the polyhydroxy saturated hydrocarbon is added thereto, and the mixture is sufficiently stirred to uniformly spread the polyhydroxy saturated hydrocarbon on the surface of the polyolefin resin. After reaching this state, a filler is added and further stirred to obtain a final mixed composition. The advantage of using this method is that it can prevent the formation of agglomerates that occur when the polyhydroxy saturated hydrocarbon and filler are directly brought into contact and dispersed, and it can improve the dispersibility of the filler in the polyolefin resin during kneading. This is something that can be done. Next, for kneading the mixture, a conventionally known device is used, such as a conventional screw extruder, a twin screw extruder, a mixing roll, a Banbury mixer,
This is carried out as appropriate using a twin-screw kneader or the like. By adding polyhydroxy saturated hydrocarbon, the kneading torque can be significantly reduced in any kneading method, which is useful for downsizing equipment and saving resources such as electric power. Molding of the film or sheet may be carried out according to a conventional film or sheet molding apparatus and method, and inflation molding using a circular die, T-die molding using a T-die, etc. may be employed as appropriate. The selection depends on the subsequent stretching method. That is, in the case of uniaxial stretching, roll stretching is usually preferred, but tubular stretching with emphasis on the uniaxial direction (take-up direction) may also be used. Further, the stretching may be carried out in one stage or in multiple stages of two or more stages. The characteristics of the uniaxial stretching of this composition are as follows: Porousness is achieved by low-magnification stretching. In other words,
When the stretching ratio is low, the interface between the matrix and the filler peels off, creating voids and forming so-called voids. Therefore, even at a low draw ratio of 1.2 times, porosity and whitening of the film occur.
This can be said to be an extremely unique phenomenon. This low-magnification stretching makes it possible to suppress anisotropy in the physical properties of the film or sheet, and also provides high surface strength. Low stretching stress. Due to the improved flexibility of the original fabric and the fact that it is possible to make it porous by stretching at a low magnification as described above, it is possible to stretch with low stress during stretching. This leads to miniaturization and simplification of equipment and is very advantageous in terms of production costs. Stretching at low temperatures is possible. Although this is related to the above, the stretching temperature can be lowered. Surprisingly,
The temperature at which porosity can be achieved ranges from the stretching temperature of a single polyolefin resin to room temperature. This is very advantageous in terms of equipment and energy saving. Normally, a film or sheet containing a filler is made porous at a stretching ratio of 3.5 to 6 times, but a film or sheet made of the composition of the present invention is made porous at a stretching ratio of 1.2 to 6 times. This can be achieved even at low magnification. However, from the viewpoint of increasing porosity and reducing the anisotropy of the physical properties of the film or sheet, it is preferably 1.5 to 3 times. Next, the case of biaxial stretching will be described. Biaxial stretching showed extremely good stretching properties in both simultaneous and sequential stretching. Biaxial stretching also allows for low stretching ratios, and uniform stretching and porosity can be achieved at 1.2x in both directions. Accordingly, a porous film with high surface strength can be obtained. Usually, the stretching ratio at which porosity can be achieved and uniform stretching can be achieved is 1.2 to 4.0 times in both directions. Preferably, it is 1.2 to 2.0 times. Further, by performing heat treatment after both uniaxial stretching and biaxial stretching, film accuracy can be stabilized. Further, known surface treatments such as corona treatment and flame treatment can also be applied. The film or sheet thus obtained exhibits the following properties. Porosity: Because it has continuous pores, it has excellent moisture permeability and gas permeability. It also has good water pressure resistance. Physical properties of film or sheet: In uniaxially stretched products, anisotropy can be reduced, so
Good vertical and horizontal balance. Particularly good tear resistance in the longitudinal direction (stretching direction). Moreover, the surface strength can be increased. Biaxially stretched products have even less anisotropy and can have higher surface strength. Both uniaxially and biaxially stretched products have good flexibility, weather resistance, and heat resistance. Processability: Can be thermally bonded and shrink wrapped. Incinurability: Easily incinerated. Does not generate toxic gas. The film or sheet obtained according to the present invention may be utilized for various purposes by taking advantage of the above-mentioned properties. Examples include applications that utilize moisture permeability for clothing (waterproof products, rain gear, etc.), battery separators, filter materials (air dust removal, mist removal, industrial wastewater, and medical applications). Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the Examples. Reference Example 1 (Production of polyhydroxy saturated hydrocarbon) Commercially available polyhydroxy polybutadiene [manufactured by Arco; R
−45HT, number average molecular weight Mn; 3110, OH group;
0.82meq/g, cis-1,4; 15%, trans-
1,4: 58%, vinyl: 27%] 3 kg, cyclohexane 3 kg and carbon-supported ruthenium (5%) catalyst (manufactured by Nippon Engelhard Co., Ltd.) 300 g,
After replacing the inside of the system with purified argon gas, high-purity hydrogen gas was supplied to the autoclave and heating was started at the same time.
100°C and an internal pressure of approximately 50 Kg/cm ² ). After maintaining this condition for about 15 hours, the hydrogenation reaction was stopped and
The polymer was purified and dried according to a conventional method. As a result of analysis by infrared absorption spectrum, the obtained polymer was confirmed to be a saturated hydrocarbon polymer containing almost no double bonds. Moreover, the -OH group content of the hydrogenated product was 0.8 meq/g. Reference Example 2 (Manufacture of polyhydroxy saturated hydrocarbon) As polyhydroxy polybutadiene, liquid polybutadiene G2000 (molecular weight 2000) manufactured by Nippon Soda Co., Ltd.
Hydrogenation was carried out in the same manner as in Reference Example 1 except that . The obtained polymer had an iodine value of 5 g/100 g,
It was a liquid with a hydroxyl value of 44 KOHmg/g and a viscosity of 775 poise at 30°C. Example 1 High-density polyethylene resin (Novatec BR002,
Novatec is a registered trademark of Mitsubishi Chemical Industries, Ltd.) 20Kg
First, 5 kg of polyhydroxy saturated hydrocarbon (obtained in Reference Example 2) was stirred and mixed in a Henschel mixer, and then 25 kg of calcium carbonate (average particle size 1.2μ, fatty acid treated) was added thereto. Further stirring and mixing were performed. The mixture thus obtained was mixed in a twin-screw kneader - DM.
−65 (Double Screw Mixer, manufactured by Japan Steel Works, Ltd.)
The mixture was kneaded and granulated. This was inflation-molded using a 40 mmφ extruder to form a film with a thickness of 70 μm. The extrusion conditions are as follows. Cylinder temperature: 170-190-210-230°C Head and die temperature: 230°C Take-up speed: 8 m/min Blow ratio = 2.0, fold diameter 314 mm The film thus obtained was uniaxially stretched using a roll stretching machine. The stretching conditions are as follows: Stretching temperature: 80°C Stretching ratio: 2.2 times Stretching speed: 11.0 m/min The stretched film is porous and sufficiently whitened, with no stretching unevenness and a porous film with a beautiful surface. It was hot. The performance of this film is shown in Table 1. The methods for measuring the performance evaluation items in Table 1 are as follows. 1 Stretchability: ◎: No cutting, uniform stretching, no stretching unevenness 〇: No cutting, almost no stretching unevenness △: No cutting, some stretching unevenness ×: Severe cutting or stretching unevenness 2 Porosity: From the following formula , calculated from the density of the film Porosity (%) = D ₀ - D / D ₀ × 100 (%) D ₀ : Density of raw film (g/cm ³ ) D: Density of stretched film (g/cm ³ ) 3 Tear strength: According to JIS P-8116. Unnotched Elmendorf tear strength for a 14 mm wide x 110 mm long sample. 4 Moisture permeability: Conforms to ASTM E26-66 (E). 5. Surface strength: A cellophane tape was attached to the surface of the film, and when it was quickly peeled off, the peeling state of the surface was observed and judged according to the following criteria. ◎: No surface peeling ○: Almost no surface peeling △: Some surface peeling ×: Large surface peeling The symbols for the compositions in the table are as shown in Table-7. Examples 2 to 8 Porous films were obtained in exactly the same manner as in Example 1, except that the stretching temperature and stretching ratio were changed as shown in Table 1, and their performance was evaluated. The results are shown in Table-1. Examples 9 to 13 Porous films were obtained in exactly the same manner as in Example 1, except that the blending ratios of the polymer, filler, and polyhydroxy saturated hydrocarbon were changed, and their performance was further evaluated. The results are shown in Table-1. Examples 14 to 17 As polyhydroxy saturated hydrocarbons (obtained in Reference Example 1), the symbol C-2 in Table 7 was used,
A porous film was obtained in the same manner as in Example 1, except that the stretching temperature was 80° C. and the magnification was varied, and its performance was further evaluated. The results are shown in Table-2. Comparative Examples 1 to 5 Example 1 except that the stretching temperature and stretching ratio were changed in a system that did not contain polyhydroxy saturated hydrocarbon.
A porous film was obtained in exactly the same manner as described above, and its performance was further evaluated. The results are shown in Table-3. Comparative Examples 6 to 8 Other than changing the blending ratio of polymer, filler, and polyhydroxy saturated hydrocarbon as shown in Table 3,
A porous film was obtained in exactly the same manner as in Example 1,
Furthermore, its performance was evaluated. The results are shown in Table-3. Comparative Examples 9 to 11 Liquid polybutadiene (manufactured by Nippon Soda Co., Ltd.,
Nisso PB G) or liquid polybutene (Nippon Petrochemical Co., Ltd., Nisseki Polybutene HV-300) was used, the stretching temperature was 80°C, and the stretching ratio was varied. A film was obtained and its performance was further evaluated. The results are shown in Table 4. Examples 18 and 19 Regarding those using talc (manufactured by Nippon Talc Co., Ltd., MS Talc) or diatomaceous earth as a filler,
Each original fabric was produced in the same manner as in Example 1, and uniaxially stretched. Furthermore, the performance of the film was evaluated in the same manner. The results are shown in Table 4. Comparative Examples 12 to 14 In the formulation of Example 1, rubbery polybutadiene (Tuffrene A, Tuffrene is manufactured by Asahi Kasei Corporation) was used as the third component instead of polyhydroxy saturated hydrocarbon.
) or rubbery EPR (Tafmar P0480,
A raw film was formed in the same manner as in Example 1, except that TAFMER (registered trademark of Mitsui Petrochemical Industries, Ltd.) was added, and uniaxial stretching was performed. Furthermore, the performance of the film was evaluated in the same manner. The results are shown in Table 4. Examples 20 and 21 Raw films were produced in the same manner as in Example 1, except that polypropylene resin (Novatek P4200Y, Novatek is a registered trademark of Mitsubishi Chemical Industries, Ltd.) was used instead of high-density polyethylene resin. Uniaxial stretching was performed. Furthermore, the performance of the film was evaluated in the same manner. The results are shown in Table 4. Examples 22 to 28 A raw film was produced using the same formulation and method as in Example 1, Examples 20 and 21, and was sequentially and simultaneously biaxially stretched using a long stretching machine (manufactured by TM Long Co., Ltd. (USA)). did. In biaxial stretching, uniform stretching was possible at low magnification in all cases. Furthermore, the performance of the obtained film was evaluated in the same manner as in Example 1. Table 5 shows the results.
Shown below. Comparative Examples 15 to 16 In the same manner as Comparative Examples 1 to 5, a raw film was obtained by performing biaxial stretching in the same manner as in Examples 22 to 28 without blending the polyhydroxy saturated hydrocarbon, Furthermore, the performance of the obtained film was demonstrated in Example 1.
It was evaluated in the same way. The results are shown in Table-5. Examples 29 and 30 The polyhydroxy saturated hydrocarbons obtained in Reference Examples 1 and 2 were blended in the same manner as in Example 1 using a Henschel mixer, and then kneaded using a Midget Banbury mixer to form a 2 mm thick press. A piece was made (press temperature 190℃). The heat resistance and weather resistance of these sample pressed pieces were measured. Heat resistance was evaluated by tensile elongation at break after an accelerated test (after 100 hours and after 1000 hours) in an oven at 100°C, and weather resistance was evaluated in a sunshine carbon arc weather meter (manufactured by Suga Test Instruments). . The results are shown in Table-6. The blank in Table 6 is the elongation at break of the pressed piece itself that has not been subjected to the accelerated test. Comparative Examples 17 to 20 Liquid polybutadiene [Nisso PBG (Nippon Soda)], liquid polybutene [Nisseki Polybutene HV-
300 (Japan Petrochemical)], hydroxyl-terminated liquid polybutadiene [Poly bd R-45HT (Idemitsu Petrochemical)], and rubbery polybutadiene [Tuffrene A (Asahi Kasei)]
A pressed piece was made in the same manner as in Examples 29 and 30, except that the following was added, and its heat resistance and weather resistance were examined. The results are shown in Table-6.

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[Table] As is clear from the above results, films or sheets obtained from compositions containing fillers and polyhydroxy saturated hydrocarbons in polyolefin resins exhibit extremely excellent stretchability and can be stretched at low ratios. In addition to achieving porosity, the film or sheet is beautiful and highly flexible. Furthermore, it has advantages such as excellent heat resistance and weather resistance. In addition, it is expected to be used in a wide range of applications as a film or sheet with high tear resistance and continuous pores.

Claims (1)

[Claims] 1. A polyolefin resin containing a filler and hydrogenated liquid polybutadiene, at least per molecule.
A porous film characterized by stretching a film or sheet obtained by melt-molding a composition comprising a polyhydroxy saturated hydrocarbon whose main chain is saturated or mostly saturated and has 1.5 hydroxyl groups. Or the manufacturing method of the sheet. 2 The blending ratio of the composition is polyolefin resin
2. The method according to claim 1, wherein the amount of filler is 25 to 400 parts by weight and the polyhydroxy saturated hydrocarbon is 1 to 100 parts by weight based on 100 parts by weight. 3. The manufacturing method according to claim 1 or 2, wherein the polyolefin resin is high-density polyethylene. 4. The manufacturing method according to claim 1 or 2, wherein the polyolefin resin is polypropylene. 5. Any one of claims 1 to 4, characterized in that when blending the composition, a filler is mixed after the polyhydroxy saturated hydrocarbon is dispersed and spread in the polyolefin resin powder. The manufacturing method described in. 6. The manufacturing method according to any one of claims 1 to 5, wherein the stretching treatment is uniaxial stretching of at least 1.2 times. 7. The manufacturing method according to any one of claims 1 to 5, wherein the stretching process is at least 1.2 times biaxial stretching.