JPH0834872A - Oriented opaque resin film - Google Patents

Abstract

PURPOSE:To prevent the occurrence of uneven whitening by producing an oriented film made of a base material comprising a thermoplastic resin containing a PP resin and a polyphenylene ether resin so as to provide a specified porosity and opacity. CONSTITUTION:A mixture containing 50-95wt.% PP resin, such as a propylene homopolymer, having a melt flow rate of about 0.3-50g/10min and a melting point of about 130-190 deg.C, 5-50wt.% polyphenylene ether base resin which consists of about 30-100wt.% polyphenylene ether resin and about 70-0wt.% aromatic alkenyl compound polymer such as PS and has a glass transition temperature of about 140-300 deg.C, and 0.1-10wt.% compatibilizer such as a styrene-grafted propylene resin etc., is melt compounded. This compound is formed into film through an extruder, and the film is stretched about 3.5-to 12-fold at least in one direction with a biaxial orientation machine and then annealed to give an opaque resin film having a porosity calculated by the formula, of 20-70% and an opacity of at least 75% and free from the occurrence of uneven whitening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has holes inside,
The present invention relates to an opaque stretched resin film. This opaque stretched resin film is useful as outdoor poster paper, label paper, drawing paper, sticker paper, etc., or as a support for bar code paper, photographic paper, thermal recording paper and thermal transfer image receiving paper.

[0002]

2. Description of the Related Art At present, a synthetic paper having fine pores inside a film obtained by stretching a propylene resin film containing an inorganic fine powder (Japanese Patent Publication No. 46-40794).
Japanese Patent Publication No. 54-31032, Japanese Patent Publication No. 60-30173, and U.S. Pat. No. 3,773,608 and U.S. Pat. No. 4,191,719) are more water resistant than pulp paper. Since it is excellent in strength, smoothness, etc., it is used as a support for election poster paper, label paper, thermal recording paper and thermal transfer image receiving paper. The synthetic paper containing these inorganic fine powders and used as a pore generating agent during the stretching of the film has fine pores whose core is the inorganic fine powders inside the resin stretched film. In addition, since the inorganic fine powder also protrudes from the surface of the resin stretched film, and there are also secondary aggregates of this inorganic fine powder (Japanese Patent Laid-Open No. 62-87390), the surface of the synthetic paper during printing or printing. This inorganic fine powder is more likely to fall off, resulting in white spots (so-called pinhole trouble). Such white spots are conspicuous and become a problem particularly when printing is performed and black printing is performed.

In addition, the inorganic fine powder that has fallen off the surface of the synthetic paper during offset printing is mixed into the ink through a blanket, causing the fluidity of the ink to be lost or reduced, so that it can be transferred from the printing machine to the printing paper. This causes a problem that the proper transfer of ink is obstructed and the finish of printed matter is deteriorated (so-called paper dust trouble). As a synthetic paper containing less paper dust, a film matrix resin and a film having a melting point higher than that of the matrix resin and a mixture of a thermoplastic resin incompatible with the matrix as a base material are stretched. Has proposed a synthetic paper having a satin-like appearance made of a stretched resin film using the high melting point resin as a pore generating agent (US Pat. No. 3,154,461 and US Pat. No. 4,438,751).
U.S. Pat. No. 4,758,462, JP-A-59-209849, and JP-B-3-24334). Specifically, these stretched films use polypropylene resin as a matrix and polyethylene terephthalate, polybutylene terephthalate, and nylon 6 as a high melting point resin that serves as a pore generating agent.

[0004]

However, in the case where nylon 6 is used as the pore generating agent, the dispersibility in the polypropylene matrix is poor, and the particle size of nylon 6 particles is 8
It becomes as large as -10 μm, the pores formed become coarse, and peko (wrinkles caused by buckling when the stretched film is curved) are easily generated, which is a problem in practicality. Also,
The stretched film using the above polyethylene terephthalate or polybutylene terephthalate as a pore-generating agent has few pores, and only a translucent synthetic paper having an opacity of 65% or less can be obtained. , Was limited to illuminated signboard paper, etc. In order to increase the generation of pores in the stretched film and increase the opacity of the synthetic paper, if the stretching temperature is made even lower than the optimum stretching temperature of polypropylene, the resin film may be broken during the stretching, or the stretch tenter may be damaged. If the film comes off from the chuck (protector for the stretched film), the production efficiency of the stretched film decreases. Further, when a propylene copolymer resin such as an ethylene / propylene random copolymer having a melting point lower than that of the propylene homocopolymer is used in order to obtain high stretching stability, white spots occur. It is an object of the present invention to provide a synthetic paper having high stretching stability and having no white spots and paper dust trouble and having high opacity.

[0005]

[Means for Solving the Problems]

[Summary of the Invention] As a result of intensive studies conducted by the present inventors in view of the above problems, the above object can be achieved by blending a specific resin in a specific ratio with a propylene-based resin. The present invention has been completed based on the findings. That is, the opaque resin stretched film of the present invention is a stretched film based on a thermoplastic resin containing 50 to 95% by weight of a propylene-based resin and 5 to 50% by weight of a polyphenylene ether-based resin. An opaque stretched resin film having a porosity of 20 to 70% calculated by the following formula and an opacity of 75% or more.

[Detailed Description of the Invention] [I] Opaque resin stretched film (1) Constituent component (a) Propylene-based resin The propylene-based resin used in the present invention is a resin mainly containing propylene. Specifically, it is a propylene homopolymer or a copolymer containing propylene as a main component and an α-olefin such as ethylene, butene-1, hexene-1, heptene-1, and 4-methylpentene-1. This copolymer may be a random copolymer or a block copolymer. Among these propylene resins, propylene homopolymer and propylene / ethylene copolymer are particularly preferable. Melt flow rate of these propylene-based resins (MFR: JIS-K7210, 230 ° C 2.16k)
g load) is 0.3 to 50 g / 10 minutes, especially 0.6 to 12
g / 10 minutes, melting point 130-190 ° C, especially 145-1
It is preferably 78 ° C.

(B) Polyphenylene ether resin The polyphenylene ether resin used in the present invention is a polyphenylene ether resin or a mixture of a polyphenylene ether resin and an aromatic alkenyl compound. The aromatic alkenyl compound used here is
It is a known material based on styrene. In particular,
Polystyrene, polystyrene modified with rubber (HIP
S), styrene / maleic anhydride copolymer, and its imidized product, styrene / acrylonitrile copolymer, acrylonitrile / butadiene / styrene copolymer, and the like, and polystyrene and rubber-modified polystyrene are preferable. The polyphenylene ether resin is
General formula (I)

[0008]

Embedded image

(Wherein each Q ¹ represents a halogen atom, a primary or secondary alkyl group, a phenyl group, an aminoalkyl group, a hydrocarbonoxy group or a halohydrocarbonoxy group, and each Q ² represents A hydrogen atom, a halogen atom, a primary or secondary alkyl group, a phenyl group, a haloalkyl group, a hydrocarbon oxy group or a halohydrocarbon oxy group, and m represents a number from 10 to 450). It is a homopolymer or a copolymer having a structure. The Q ¹
And Q ² is preferably a primary alkyl group,
For example, methyl, ethyl, n-propyl, n-butyl,
n-amyl, 2-methylbutyl, n-hexyl, 2,3
-Dimethylbutyl, 2-, 3- or 4-methylpentyl or heptyl. Further, a preferable secondary alkyl group is, for example, isopropyl, sec-butyl or 1-ethylpropyl. Often Q ¹
Is an alkyl group or a phenyl group, particularly an alkyl group having 1 to 4 carbon atoms, and Q ² is a hydrogen atom. Suitable polyphenylene ether homopolymers include, for example, 2,6
A dimethyl 1,4-phenylene ether unit. Suitable copolymers include the above units and 2,
It is a random copolymer composed of a combination with 3,6-trimethyl-1,4-phenylene ether units. Many suitable homopolymers or random copolymers are described in patent publications and literature. Also suitable are polyphenylene ethers containing molecular moieties that improve properties such as molecular weight, melt viscosity and / or impact strength.

The polyphenylene ether resin used here is 30 to 100% by weight of polyphenylene ether resin.
And 70 to 0% by weight of the aromatic alkenyl compound polymer, and more preferably 50 to 100% by weight of the polyphenylene ether resin and 0 to 50% by weight of the aromatic alkenyl compound polymer. The glass transition temperature of the polyphenylene ether-based resin is 140 to 300 ° C., preferably a film stretching temperature (° C.) or higher, more preferably a film stretching temperature +5 (° C.) or higher, particularly preferably a film stretching temperature. It is +10 (° C) or higher.
When the glass transition temperature of the polyphenylene ether-based resin is lower than the stretching temperature of the film, the stretched film has a small amount of voids and lacks opacity.

(C) Other compounding ingredients In addition to the above-mentioned constituents, a compatibilizing agent, a weathering agent, an antistatic agent and the like can be preferably incorporated in the film substrate of the present invention. Compatibilizer As the compatibilizer used as an optional compounding component suitable in the present invention, any compatibilizer may be used as long as it can improve the compatibility between the polyphenylene ether resin and the propylene resin, which are the essential constituents. . Specifically, polyphenylene ether resin-grafted propylene-based resin, styrene-grafted propylene-based resin, styrene
Examples thereof include hydroxyethyl methacrylate graft ethylene / propylene copolymer rubber, partially hydrogenated aromatic alkenyl compound / conjugated diene block copolymer, and the like. Such a compatibilizer is commercially available on the market as the styrene-grafted propylene-based resin under the trade name of "VMX" from Mitsubishi Petrochemical Co., Ltd., and the partially hydrogenated aromatic alkenyl compound / conjugated diene block copolymer. The product is sold under the trade name of "Grayton G" by Shell Chemical Co., Ltd., under the trade name of "Septon" by Kuraray Co., Ltd., and under the trade name of "Tough Tech" by Asahi Kasei. Can be obtained. The amount of these compatibilizers to be added is 0.1 to 10% by weight, especially 0.5 to 1% by weight in the base material.
It is preferable to contain 0% by weight.

(D) Additional component (optional component) The resin component for film molding in the present invention may contain a stabilizer, an ultraviolet absorber, a dispersant, a dye, a pigment and the like in addition to the above components. In particular, for the purpose of improving the hue, it is effective to add a white pigment such as titanium oxide or zinc sulfide, a blue pigment such as ultramarine or phthalocyanine, or a dye. If necessary, 30% by weight or less of the resin component may be replaced with high-density polyethylene, linear low-density polyethylene, nylon 6, nylon 66, or polyethylene terephthalate.

(2) Blending amount In the present invention, when the propylene resin is contained in the base material in an amount of less than 50% by weight, the stretch moldability is poor. When the content is more than 95% by weight, the amount of voids generated is small and the resulting stretched film lacks opacity. Also, the polyphenylene ether resin is 50% by weight.
If the amount exceeds 5, there is a problem that the stretchability is poor,
If the amount is less than wt%, the amount of voids generated is small and the opacity is poor.

[II] Production of Stretched Film The stretched film of the present invention comprises a resin composition containing a propylene-based resin, a polyphenylene ether-based resin, and optionally a compatibilizer, and the like. By kneading at a temperature exceeding, for example, 200 to 300 ° C., the polyphenylene ether resin is dispersed as fine particles (preferably 0.1 to 3 μm) in the propylene resin, extruded in a film form from a die, and then this film is formed. 3.5 at least in one direction at a temperature (for example, 140 to 165 ° C.) such that the desired porosity is obtained.
-12 times, preferably 3.5-5. In the direction of extrusion (MD).
It is obtained by stretching 5 times and 4 to 12 times in the width direction (TD). If necessary, it may be laminated with another resin layer when producing the stretched film of the present invention. Examples of the other resin layer include olefin resins such as ethylene resin and propylene resin, saturated polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon 6 and nylon 66, polyvinyl chloride resin, polystyrene and the like. Can be mentioned. Such other resin layer may contain a filler such as calcium carbonate, titanium dioxide, clay, and barium sulfate.

[III] Physical Properties of Stretched Resin Film As for the physical properties of the stretched resin film obtained by the above stretching, the porosity is 20 to 70%, preferably 25 to 60%, and the opacity (JIS-P8138) is 75%. Or more, preferably 8
0 to 100%. When the porosity is less than 20%, light reflection is insufficient and a paper-like texture cannot be obtained. Further, if the porosity exceeds 70%, the strength of the synthetic paper becomes brittle. However, when the opacity is less than 75%, the hiding property is insufficient, and when printing is performed on the booklet, the printing on the next page can be seen through, and in the case of double-sided printing, the back surface is not printed. The print looks dull, and it becomes difficult to see the print / printed surface on that side.

[IV] Use The stretched resin film as described above can be used as a poster paper, a drawing paper, or by providing a gelatin layer, a heat-sensitive recording coating layer and an image-receptive recording layer on the surface of the film. It is useful as a support for use as paper, thermal recording paper, and thermal transfer image receiving paper.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following experimental examples. The evaluations in Examples and Comparative Examples were evaluated by the evaluation methods shown below. [I] Evaluation Method Opacity The opacity was measured according to JIS-P8138. Using a pencil hardness meter (scratch tester) manufactured by Toyo Seiki Co., Ltd., a pencil of hardness HB set to be perpendicular to the obtained film was loaded with a load of 200 g to give 20
Draw a line segment at a speed of 0 sec / m. Put the film on which this line segment is drawn on a white paper with an optical density of 0.2 so that the drawing surface is in contact with the white paper surface and see through the line. The degree of minute was visually observed and judged according to the following criteria. Bad: The line segment can be easily read. Good: Difficult or unreadable line segment. Occurrence of white spots 300 mm in length and 300 in width from the center of the obtained film.
One mm sample is cut out and set on a translucent table for drafting, and the presence or absence of whitening spots is visually observed. Stability of Stretching When 10 test pieces are carried out, the number of test pieces that have been completely stretched without breakage or detachment of the chuck during the stretching is measured. Beck's smoothness The Beck's smoothness was measured according to JIS-P8119.

[II] Experimental Example Example 1 79 parts by weight of propylene homopolymer "Mitsubishi Polypro TA-8" (trade name, manufactured by Mitsubishi Petrochemical Co., Ltd.) having a melt flow rate of 0.8 g / 10 minutes and a melting point of 174 ° C. , Intrinsic viscosity in chloroform at 30 ° C. 0.3 dl / g, glass transition temperature 2
12 parts by weight of polyphenylene ether resin (manufactured by Nippon Polyether Co., Ltd.) at 10 ° C., 3 parts by weight of rubber-reinforced polystyrene resin “HT76” (trade name, manufactured by Mitsubishi Kasei Co., Ltd.),
Styrene-grafted propylene-based resin “V
MX DN65X "(trade name of Mitsubishi Petrochemical Co., Ltd.) 6 parts by weight and a mixture of 3 parts by weight of titanium dioxide at 210 ° C.
After melt-kneading with a twin-screw extruder (manufactured by Japan Steel Works) set to, extruded in a strand form from a die, cooled and cut to obtain pellets. The pellets are melted, compressed, and cooled by a press molding machine set at 260 ° C., length 120 mm,
A press sheet having a width of 120 mm and a thickness of 1.5 mm was obtained.
This press sheet is a small biaxial stretching machine (made by Iwamoto Seisakusho)
After being heated to 160 ° C., the film was sequentially stretched 5 times in the longitudinal direction and then 5 times in the transverse direction, and then annealed for 30 seconds to obtain a stretched film. The thickness, porosity, opacity, hiding property, presence or absence of white spots, stretching stability, and Beck's smoothness of the obtained film were measured, and the results are shown in Table 1.

Examples 2 to 4 and Comparative Examples 1 to 3 Stretched films were produced in the same manner as in Example 1 except that the composition and stretching temperature in Example 1 were changed to those shown in Table 1. The evaluation was performed in the same manner as in Example 1. Table 1 shows the evaluation results.

Example 5 79 parts by weight of a propylene homopolymer "Mitsubishi Polypro TA-8" (trade name, manufactured by Mitsubishi Petrochemical Co., Ltd.) having a melt flow rate of 0.8 g / 10 minutes and a melting point of 174 ° C. at 30 ° C. Polyphenylene ether resin with an intrinsic viscosity of 0.3 dl / g in chloroform and a softening point of 170 ° C. (Japan Polyether Co., Ltd.)
12 parts by weight, rubber-reinforced polystyrene resin "HT7"
6 "(trade name of Mitsubishi Kasei Co., Ltd.), 3 parts by weight of styrene-grafted propylene-based resin" VMX DN "as a compatibilizer
65X "(trade name of Mitsubishi Petrochemical Co., Ltd.) and 3 parts by weight of titanium dioxide were melt-kneaded by a twin-screw extruder (manufactured by Japan Steel Works) set at 210 ° C., and then from a die. It was extruded into a sheet and cooled to obtain a film.

The film was heated by contacting it with a heating roll at 145 ° C., and then stretched 4.8 times in the machine direction. Then, after cooling the film to a temperature of 60 ° C., 165 in the oven using a tenter type transverse stretching apparatus.
After heating with hot air of ℃, stretched laterally 8 times, 170 ℃
After annealing with hot air, the ears were slit to obtain an opaque stretched resin film. The stretching stability was good. The physical properties of the obtained stretched film were as follows. Thickness: 100 μm Porosity: 44% Opacity: 98% Beck's smoothness: 3,000 seconds Concealability: Whitening spots: None

Example 6 70 parts by weight of propylene homopolymer "Mitsubishi Polypro TA-8" (trade name, manufactured by Mitsubishi Petrochemical Co., Ltd.) having a melt flow rate of 0.8 g / 10 minutes and a melting point of 174 ° C., and an average particle size of 1 0.5 μm
20 parts by weight of calcium bicarbonate and 10 parts by weight of high-density polyethylene having a melt index of 11 g / 10 min were melt-kneaded by an extruder set at a temperature of 260 ° C., and then a die set at a temperature of 250 ° C. It was extruded into a sheet and cooled to a temperature of 60 ° C. with a cooling roll.

This film was heated by contacting it with a heating roll at 145 ° C., and then stretched 5 times in the machine direction. A melt flow rate of 4 g / 10 minutes on both sides of this longitudinally stretched film,
Propylene homopolymer having a melting point of 174 ° C. and a crystallinity of 67% “Mitsubishi Polypro MA-4” (trade name of Mitsubishi Petrochemical Co., Ltd.)
76 parts by weight, an intrinsic viscosity in chloroform at 30 ° C. of 0.3 dl / g, a softening point of 170 ° C., a polyphenylene ether resin (manufactured by Nippon Polyether Co., Ltd.) 12 parts by weight, a rubber-reinforced polystyrene resin “HT76” (Mitsubishi Kasei Co., Ltd.
Product name: 3 parts by weight, styrene-grafted propylene resin "VMXDN65X" as a compatibilizer (Mitsubishi Petrochemical Co., Ltd.)
Product name) A mixture containing 6 parts by weight and 3 parts by weight of titanium dioxide is melt-kneaded by a twin-screw extruder (manufactured by Japan Steel Works) set at 270 ° C, and then formed into a sheet from a die set at 250 ° C. It was extruded and melt-pressed with a roll to obtain a laminate.

Next, after cooling this laminate to a temperature of 60 ° C., it was heated in the oven with hot air of 165 ° C. using a tenter type transverse stretching device, and then stretched 8.5 times in the transverse direction. After annealing with 170 ° C. hot air, the ears were slit to obtain an opaque stretched resin film. Also, this film is mounted in half and half format (vertical 788 m
m, width 545 mm) and using offset ink "TSP-400" (trade name) manufactured by Toyo Ink Co., Ltd. and offset two-color printing machine "Diamond Printing Machine" (trade name) manufactured by Mitsubishi Heavy Industries, Ltd. Print the number of prints until 2,000 sheets are printed in two colors and the ink edge pile on the blanket or the falling paper dust on the blanket adversely affects the printing (the number of printable sheets until a so-called paper dust trouble occurs). As a result, no signs of paper dust trouble were found up to 1,500 sheets.

Comparative Example 4 70 parts by weight of propylene homopolymer "Mitsubishi Polypro TA-8" (trade name of Mitsubishi Petrochemical Co., Ltd.) having a melt flow rate of 0.8 g / 10 minutes and a melting point of 174 ° C., an average particle size of 1 0.5 μm
20 parts by weight of calcium bicarbonate and 10 parts by weight of high-density polyethylene having a melt index of 11 g / 10 min were melt-kneaded by an extruder set at a temperature of 260 ° C., and then a die set at a temperature of 250 ° C. It was extruded into a sheet and cooled to a temperature of 60 ° C. with a cooling roll.

This film was heated by contacting it with a heating roll at 145 ° C., and then stretched 5 times in the machine direction. A melt flow rate of 4 g / 10 minutes on both sides of this longitudinally stretched film,
Propylene homopolymer having a melting point of 174 ° C. and a crystallinity of 67% “Mitsubishi Polypro MA-4” (trade name of Mitsubishi Petrochemical Co., Ltd.)
60 parts by weight, calcium bicarbonate 4 with an average particle size of 1.5 μm
A composition consisting of 0 parts by weight was melt-kneaded by an extruder set at a temperature of 260 ° C., then extruded in a sheet form from a die set at a temperature of 260 ° C., melt-pressed by a roll to obtain a laminate.

Next, after cooling this laminate to a temperature of 60 ° C., it was heated in the oven with hot air at 165 ° C. using a tenter type transverse stretching device, and then stretched 8.5 times in the transverse direction. After annealing with 170 ° C. hot air, the ears were slit to obtain an opaque stretched resin film. When the number of printable sheets of this film was evaluated in the same manner as in Example 6, it was 600.

[0028]

[Table 1]

[0029]

The opaque stretched resin film of the present invention is a stretched film based on a thermoplastic resin containing 50 to 95% by weight of a propylene resin and 5 to 50% by weight of a polyphenylene ether resin. Since it is constituted, it is possible to obtain a stretched resin stretch film having excellent opacity, which does not cause white spots or paper dust trouble.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Kurasawa 1 Toho-cho, Yokkaichi-shi, Mie Prefecture Yokkaichi Research Institute, Mitsubishi Petrochemical Co., Ltd. (72) Inventor Koji Nishida 1 Toho-cho, Yokkaichi-shi, Mie Address Mitsubishi Petrochemical Co., Ltd. Yokkaichi Research Institute

Claims (2)

[Claims] 1. A stretched film based on a thermoplastic resin containing 50 to 95% by weight of a propylene-based resin and 5 to 50% by weight of a polyphenylene ether-based resin, wherein the stretched film has the following physical properties. Calculated porosity 20-70
%, An opacity of 75% or more, an opaque stretched resin film. 2. The opaque stretched resin film according to claim 1, wherein the thermoplastic resin contains 0.1 to 10% by weight of a compatibilizing agent.