JP6700616B2 - Semi-transparent stretched film - Google Patents

Description

  The present invention relates to a translucent stretched film including at least a base material layer and a surface layer.

  Conventionally, translucent paper, glassine paper, paraffin paper, and sulfuric acid paper, which have semi-transparency, have excellent visibility of characters and patterns printed on the surface, and the contents can be confirmed. It is used for medicine wrapping paper, food wrapping paper, cooking sheets, book covers, etc. However, the translucent paper loses the translucency when the thickness is increased, and the mechanical strength becomes insufficient when the thickness is decreased. In addition, paper dust is generated during printing, cutting, packaging, and the like, which may cause problems such as deterioration of printability and cutting workability, and contamination of packages. Further, it has lower moisture resistance, water resistance and oil resistance than a plastic film, and may not be used for packaging foods and the like containing water or oil. Furthermore, paper generally does not have heat sealability, and cannot be used in a packaging form that requires heat sealability.

  On the other hand, a plastic film has excellent moisture resistance, water resistance and oil resistance, and has good mechanical strength, and is therefore used for wrapping paper for foods, chemicals and the like. However, the plastic film has high transparency, and it is difficult to visually recognize characters and patterns unless printed on the entire surface, and in addition, it is difficult to obtain a high-class feeling and design because the texture is uniform. Therefore, the plastic film has a problem that it is difficult to attract the attention of consumers.

  In addition, a pencil writing property is required for a transparent paper or the like due to its use, but a plastic film cannot be written with a pencil or the like because the surface is too smooth. Further, since the plastic film has a glossy appearance as compared with paper, it may not be used as a substitute for paper.

  Patent Document 1 proposes a polypropylene biaxially stretched film having a pearl luster formed from a polypropylene resin composition containing polypropylene and a specific calcium carbonate powder.

  Patent Document 2 proposes an opaque polyolefin film composed of a crystalline polyolefin and a cyclic olefin resin.

  US Pat. No. 6,096,849 discloses an opaque polymer film comprising a polymer matrix and a base layer comprising a solid, composed of syndiotactic polystyrene polymer, a cavitation agent comprising non-hollow particles, and at least one additional layer. Proposed. Patent Document 3 describes that an ethylene norborene copolymer is further contained in the polymer film as a cavitation agent.

JP-A-11-005852 JP-A-8-73618 Special table 2003-522054 gazette

However, regarding the above-mentioned Patent Document 1, calcium carbonate used for a polypropylene biaxially stretched film is opaque, and a translucent film cannot be obtained. In addition, the package may be contaminated due to the particles falling off, or the printing plate may be contaminated for printing purposes, and the cutting workability is not satisfactory.
Further, regarding the above-mentioned Patent Document 2, since the opaque polyolefin film is a single-layer film of a crystalline olefin and a cyclic olefin resin, it has a glossy appearance and does not have a paper-like texture, and also has a writing property with a pencil or the like. It is something that is not done.
Furthermore, the polymer film described in Patent Document 3 is opaque and does not have translucency. Further, it does not describe a surface layer having a matte effect, and the polymer film does not have a paper-like texture.

Under such circumstances, it is a plastic film that has higher moisture resistance, water resistance, oil resistance, and mechanical strength than paper, but also has semi-transparency and a paper-like appearance, and is preferably excellent in printing. A film having suitability and, if desired, pencil writing property is desired.
Accordingly, it is an object of the present invention to provide a translucent stretched film having a paper-like appearance, preferably a translucent stretched film having excellent printability and optionally pencil writability. ..

  As a result of intensive studies, the present inventors have found that the paper-like appearance of the translucent stretched film is related to the gloss (glossiness) on the surface side and the non-uniformity of whiteness due to the base material layer. I found it. And, the present inventors are a semitransparent stretched film including at least a base material layer and a surface layer, wherein the base material layer has a crystalline thermoplastic resin A having a melting point of 120 to 175° C. and an amorphous material. Crystalline thermoplastic resin having one or more layers containing at least a thermoplastic resin B as a resin component, and the surface layer has a melt mass flow rate of 0.02 to 2 g/10 minutes at 190° C. and 2.16 kg. It has been found that the above problems can be solved by a semitransparent stretched film containing at least D as a resin component and having a total light transmittance of 35 to 85%, and completed the present invention.

That is, the present invention includes the following.
[1] A semitransparent stretched film including at least a base material layer and a surface layer,
The base material layer has at least one layer containing at least a crystalline thermoplastic resin A having a melting point of 120 to 175° C. and an amorphous thermoplastic resin B as resin components,
The surface layer contains at least a crystalline thermoplastic resin D having a melt mass flow rate of 0.02 to 2 g/10 minutes at 190° C. and 2.16 kg as a resin component, and a total light transmittance of 35 to 85%. There is a semitransparent stretched film.
[2] The semitransparent stretched film according to [1], wherein the amorphous thermoplastic resin B has a glass transition temperature of 135 to 185°C.
[3] The semitransparent stretched film according to [1] or [2], wherein the base material layer further contains, as a resin component, a crystalline thermoplastic resin C having a melting point of 200 to 280°C.
[4] Any one of [1] to [3], wherein the content of the amorphous thermoplastic resin B in the base material layer is 2 to 40 mass% based on the total mass of the resin components of the base material layer. The semitransparent stretched film according to 1.
[5] The semitransparent stretched film according to any one of [1] to [4], wherein the surface layer further contains a crystalline thermoplastic resin A′ as a resin component.
[6] In the surface layer, the content of the crystalline thermoplastic resin D is 1 to 60% by mass based on the total mass of the resin components of the surface layer, [1] to [5]. Semi-transparent stretched film.
[7] The surface layer further contains an amorphous thermoplastic resin B′ and/or a crystalline thermoplastic resin C′ as a resin component, and the amorphous thermoplastic resin B′ and/or the crystalline thermoplastic resin. The semitransparent stretched film according to any one of [1] to [6], wherein the total content of C′ is 5 to 30% by mass based on the total mass of the resin components of the surface layer.
[8] The semitransparent stretched film according to any one of [1] to [7], wherein the amorphous thermoplastic resin B is an amorphous cyclic olefin copolymer.
[9] The semitransparent stretched film according to any one of [1] to [8], wherein the crystalline thermoplastic resin D is high-density polyethylene.
[10] The translucent stretched film according to any one of [1] to [9], which has a heat seal layer on the surface opposite to the surface on which the surface layer is laminated.
[11] The semitransparent stretched film according to any one of [1] to [10], wherein the surface layer side has a 60-degree specular gloss of 1 to 20%.

The semi-transparent stretched film of the present invention has a white semi-transparency, and also has excellent mechanical strength, moisture resistance, water resistance and oil resistance, and therefore has a label, a tape substrate, a printing substrate, a poster paper, It can be suitably used for a heat-sensitive paper base material, a recording paper base material and the like. In addition, it has a non-uniform whiteness like the texture of paper and has a matte appearance, so it has the texture of paper (paper-like appearance), and as a result, it is easy to use as a substitute for paper. ..
Further, in order to obtain a matte appearance, the surface is appropriately roughened so that it is possible to write with a pencil like paper.

The translucent stretched film of the present invention has the texture of paper even if it does not contain inorganic particles. In such an embodiment, there is no problem that the package is not contaminated due to the dropping of the inorganic particles, the printing plate is not contaminated for printing purposes, the cutting surface is roughened during cutting, and the cutting blade is consumed quickly.
Furthermore, in one embodiment of the present invention, the semitransparent stretched film of the present invention has excellent printability and heat sealability, and thus can be preferably used for food packaging applications.

  In the present specification, “to” means the above and the following. That is, the notation α to β means α or more and β or less or β or more and α or less, and includes α and β as a range.

The present invention is a semitransparent stretched film including at least a base material layer and a surface layer, wherein the base material layer has a crystalline thermoplastic resin A having a melting point of 120 to 175°C (hereinafter, also referred to as crystalline resin A). And a non-crystalline thermoplastic resin B (hereinafter, also referred to as the non-crystalline resin B) as resin components at least one layer, and the surface layer is a melt at 190° C. and 2.16 kg. The present invention relates to a semitransparent stretched film having a total light transmittance of 35 to 85%, which contains at least a crystalline thermoplastic resin D having a mass flow rate of 0.02 to 2 g/10 minutes as a resin component. The translucent stretched film of the present invention has at least a substrate layer and a surface layer laminated, and is composed of a plurality of layers.
Here, the crystalline thermoplastic resin means that the temperature is raised from -40° C. to 300° C. at a rate of 20° C./min under a nitrogen flow using DSC, held at 300° C. for 5 minutes, and at 20° C./min This is a thermoplastic resin in which a clear melting peak appears in the DSC curve when cooled to -40°C, held at -40°C for 5 minutes, and then again heated to 300°C at 20°C/min.
Further, the amorphous thermoplastic resin refers to a thermoplastic resin in which a clear melting peak does not appear in the above measurement using DSC.
Further, "having one or more layers containing at least a crystalline thermoplastic resin A having a melting point of 120 to 175° C. and an amorphous thermoplastic resin B as resin components" means that the base material layer is It means that a layer containing at least a crystalline resin A and an amorphous resin B as a resin component (the resin A and B are used in combination) can be included in a single layer or a plurality of layers as a layer constituting a base material layer. And the base material layer has a layer containing at least the crystalline resin A and the amorphous resin B as a resin component (using the resins A and B together) as another layer adjacent to the base material layer. Does not mean.

The translucent stretched film of the present invention includes a base material layer. The base material layer has one or more layers containing at least the crystalline resin A and the amorphous resin B as resin components. That is, the base material layer may be either a single layer or a plurality of layers. When the base material layer is a plurality of layers, it contains at least the crystalline resin A and the amorphous resin B as resin components (the resin The layer (using both A and B) may be a single layer or a plurality of layers.
Since the base material layer of the semitransparent stretched film contains the crystalline resin A and the amorphous resin B, the dispersed state of the amorphous resin B in the crystalline resin A and the voids formed around it Since the parts have various sizes, a partial difference occurs in the transmittance, and non-uniformity of whiteness such as the texture of paper is obtained. Further, by containing the crystalline thermoplastic resin D having a melt mass flow rate within the above range in the surface layer, a surface layer having a matte appearance can be obtained. By combining such a base material layer and a surface layer, a semitransparent stretched film having a semitransparent paper-like appearance can be obtained. The amorphous resin B itself in the base layer of the semitransparent stretched film is not in a hollow state but in a solid state (or a non-hollow state).

  The semitransparent stretched film of the present invention has a total light transmittance of 35 to 85%. If the total light transmittance is less than 35%, it becomes opaque, and it becomes difficult to confirm the contents when used for packaging. On the other hand, when it exceeds 85%, the transparency becomes too high, and the visibility of characters, patterns, etc. printed on the film surface deteriorates. The total light transmittance of the semitransparent stretched film of the present invention is preferably 40% to 80%, more preferably 50% to 75%, and further preferably 52 to 70%. When the total light transmittance is within the above range, the stretched film becomes translucent, which is preferable. In the present invention, the total light transmittance is a value measured according to JIS K 7361, and was measured using a haze meter NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd.

  The melting point of the crystalline resin A is 120 to 175°C, preferably 123 to 170°C, more preferably 126 to 166°C, further preferably 130 to 164°C, and particularly preferably 135 to 163°C. When the melting point of the crystalline resin A is lower than 120° C., the heat resistance of the obtained stretched film is lowered and the productivity of the stretched film is lowered. When the melting point of the crystalline resin A exceeds 175° C., it becomes difficult to control the size of the fine dispersion of the amorphous resin B in the crystalline resin A.

  The glass transition temperature of the crystalline resin A is preferably 50°C or lower, more preferably -30°C to 30°C. When the glass transition temperature of the crystalline resin A satisfies the above requirements and the amorphous resin B has a specific glass transition temperature as described later, when the film is stretched, the crystalline resin A and the amorphous resin B are stretched. It is preferable because an appropriate void can be formed between the interface with B. Further, the productivity of the stretched film and the heat resistance, flexibility, low temperature brittleness and the like of the obtained stretched film are favorable, which is preferable.

  In the present invention, the melting point and glass transition temperature of the crystalline resin A were measured using an input compensation type DSC, DiamondDSC manufactured by Perkin-Elmer.

  The melt mass flow rate of the crystalline resin A at 230° C. and 2.16 kg is preferably 0.5 to 10 g/10 minutes, more preferably 1 to 8 g/10 minutes, further preferably 2 to 6 g/10 minutes, particularly It is preferably 2.5 to 6 g/10 minutes. By setting the melt mass flow rate within the above range, the fluidity of the resin is in an appropriate range, and a stretched film can be manufactured with an accurate thickness. In addition, the size of the fine dispersion of the amorphous resin B in the crystalline resin A can be easily controlled, and the desired total light transmittance can be easily obtained. In the present invention, the melt mass flow rate of the crystalline resin A was measured according to JIS K 7210:1999 using a melt indexer manufactured by Toyo Seiki Co., Ltd. Here, the fine dispersion of the amorphous resin B itself is not in a hollow state but in a solid state (also referred to as a non-hollow state).

  The crystalline resin A is not particularly limited as long as it is a crystalline thermoplastic resin having a melting point of 120 to 175° C., for example, a crystalline polyolefin resin, a crystalline acetal resin, a crystalline polyester resin and a crystalline resin. Among the polyamide resins, those having a melting point of 120 to 175° C. and the like can be mentioned. These may be used alone or in combination of two or more. Among these, crystalline polyolefin resins are preferable, and above all, crystalline polyolefin resins exhibiting the melting point of the crystalline resin A or preferably the glass transition temperature are excellent in stretchability and desired at an appropriate film stretching temperature. It is preferable because a semitransparent stretched film exhibiting the total light transmittance of is easily obtained.

  As the crystalline polyolefin-based resin, ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like are used as monomers. Examples thereof include homopolymers and copolymers, and these can be used alone or as a mixture of two or more kinds. Among these, crystalline polypropylene resins are preferable, and particularly from the group consisting of crystalline propylene homopolymer and crystalline propylene-ethylene copolymer (hereinafter, also referred to as crystalline propylene-ethylene copolymer). At least one selected is preferable. When a crystalline propylene homopolymer (crystalline polypropylene homopolymer) is used for the crystalline resin A, the mechanical strength and heat resistance of the film tend to be improved. When a crystalline propylene-ethylene copolymer is used as the crystalline resin A, the film tends to have improved breakability at low temperatures and tends to have a reduced surface gloss.

  Therefore, the crystalline resin A may be a crystalline propylene homopolymer alone or a mixture of a crystalline propylene homopolymer and a copolymer of propylene and ethylene and/or another polymer. Alternatively, it is possible to use only a copolymer of propylene and ethylene and/or another polymer. In addition, the crystalline resin A can be used in different types according to the required quality. The other polymer may be any polymer that can be used as the crystalline resin A, and is a crystalline polyolefin resin other than the above-mentioned crystalline propylene homopolymer and copolymer of propylene and ethylene. It may be a crystalline polyester resin, a crystalline polyamide resin, a crystalline acetal resin, or the like. Preferably, the crystalline resin A is preferably a combination of two components, a crystalline propylene homopolymer and a crystalline propylene-ethylene copolymer. In this case, the preferable mass ratio of the crystalline propylene homopolymer and the crystalline propylene-ethylene copolymer is as follows: crystalline propylene homopolymer (P1): crystalline propylene-ethylene copolymer (P2)=90:10 It is 99.5:0.5, a more preferable mass ratio is P1:P2=93:7 to 99:1, and a more preferable mass ratio is P1:P2=95:5 to 97:3.

  As the crystalline propylene homopolymer, a crystalline isotactic polypropylene resin is preferable. In the present invention, the crystalline isotactic polypropylene resin preferably has a mesopentad fraction ([mmmm]), which is a degree of stereoregularity determined by high temperature nuclear magnetic resonance (NMR) measurement, preferably 90 to 98%. Yes, and more preferably 91 to 95%. When the mesopentad fraction [mmmm] is 90% or more, the crystallinity of the resin is improved due to the high stereoregular component, and high thermal stability and mechanical strength are obtained. On the other hand, when the mesopentad fraction [mmmm] is preferably 98% or less, the stretchability becomes good.

The high temperature NMR apparatus for measuring the mesopentad fraction ([mmmm]) is not particularly limited, and a commercially available high temperature nuclear magnetic resonance (NMR) apparatus capable of measuring the stereoregularity of polyolefins. For example, a high temperature Fourier transform nuclear magnetic resonance apparatus (high temperature FT-NMR) JNM-ECP500 manufactured by JEOL Ltd. can be used. The observation nucleus is ¹³ C (125 MHz), the measurement temperature is 135° C., and ortho-dichlorobenzene (a mixed solvent of ODCB:ODCB and deuterated ODCB (volume mixing ratio=4/1)) is used as a solvent. The high temperature NMR method can be carried out by a known method, for example, the method described in “Japan Analytical Chemistry/Polymer Analysis Research Round-table, New Edition Polymer Analysis Handbook, Kinokuniya Bookstore, 1995, p. 610”. .. The measurement mode is single pulse proton broadband decoupling, pulse width 9.1 μsec (45° pulse), pulse interval 5.5 sec, number of integrations 4500 times, and shift reference is CH ₃ (mmmm)=21.7 ppm.

  The pentad fraction, which represents the degree of stereoregularity, is a combination of a pair of pentads of "meso (m)" in the same direction and "racemo (r)" in the opposite direction (mmmm or mrrm). Etc.) is calculated as a percentage from the integrated value of intensity of each signal. Regarding attribution of signals derived from mmmm, mrrm, etc., reference is made to the description of spectra such as “T. Hayashi et al., Polymer, 29, 138 (1988)”. The mesopentad fraction ([mmmm]) can be controlled by appropriately adjusting the polymerization conditions of the polypropylene resin, the type of catalyst, the amount of catalyst, and the like.

  As the crystalline propylene homopolymer, known methods, for example, using a Ziegler catalyst system composed of titanium and aluminum compounds, a method of polymerizing propylene in a hydrocarbon solvent, a method of polymerizing in liquid propylene (bulk polymerization), a gas What was manufactured by the method of polymerizing in a phase, etc. can be used. Moreover, a commercially available product can also be used. Typical commercial products include, for example, homopolymers of Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., PC412A manufactured by Sun Allomer Co., Ltd., and Novatec (registered trademark) series manufactured by Japan Polypro Co., Ltd. Among them, homopolymers, Daploy series manufactured by Borealis, 5014L series manufactured by Korea Oil Chemicals Co., Ltd., and homopolymers selected from Sumitomo Noblene (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd. may be mentioned.

  As the crystalline copolymer of propylene and ethylene, a random copolymer of propylene and ethylene and a block copolymer of propylene and ethylene are preferably used, and 50% by mass or less of ethylene in the copolymer is used. Those contained in are more preferable. Typical commercially available products include, for example, copolymers of Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., copolymers of Novatech (registered trademark) series manufactured by Nippon Polypro Co., Ltd., and Win. Examples include TEC (registered trademark) series and Sumitomo Noblen (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd., which are copolymers.

  Examples of the crystalline polyamide resin include ring-opening polymerization type aliphatic polyamide and amide elastomer. For example, nylon 12 (PA12) having a melting point in the range of 120 to 175° C. can be used. The crystalline polyamide resin can be used alone or in combination of two or more kinds.

  Examples of the crystalline acetal resin include homopolymers such as polyoxymethylene resin and polyoxyethylene resin, and copolymers thereof. The crystalline acetal resin may be used alone or in combination of two or more.

  The crystalline resin A is preferably 60% by mass or more, more preferably 65% by mass or more, further preferably 75% by mass or more, particularly preferably 85% by mass, based on the total mass of the resin components contained in the base material layer. It can be used in the above amounts. The crystalline resin A is preferably 98% by mass or less, more preferably 97.5% by mass or less, still more preferably 96% by mass or less, based on the total mass of the resin components contained in the base material layer, and even more. It can be used in an amount of preferably 94% by mass or less, particularly preferably 93% by mass or less. For example, when the base material layer includes two or more layers containing the crystalline resin A and the amorphous resin B, the resin component contained in the layer containing the crystalline resin A and the amorphous resin B. It is preferable that the mass% of the crystalline resin A in each layer is within the above range based on the total mass of By using the crystalline resin A in the above range, a film having excellent stretchability and mechanical strength can be easily obtained.

Next, the amorphous resin B will be described. The amorphous resin B is a resin whose melting point is not confirmed in the above-mentioned DSC measurement, but whose glass transition temperature is confirmed. The glass transition temperature of the amorphous resin B is preferably 220° C. or lower, more preferably 190° C. or lower, further preferably 185° C. or lower, still more preferably 180° C. or lower, and particularly preferably It is 174°C or lower, and particularly preferably 164°C or lower. Further, the glass transition temperature of the amorphous resin B is preferably 40° C. or higher, more preferably 50° C. or higher, even more preferably 135° C. or higher, still more preferably 140° C. or higher. It is preferably 144°C or higher, and particularly preferably 148°C or higher.
When the glass transition temperature of the amorphous resin B is within the above range, an appropriate void portion can be formed between the interfaces of the crystalline resin A and the amorphous resin B during stretching of the film, which is preferable. .. In the present invention, the glass transition temperature of the amorphous resin B was measured using an input compensation type DSC, Diamond DSC manufactured by Perkin-Elmer.

  The amorphous resin B has a melt mass flow rate at 260° C. and 2.16 kg of preferably 1 to 15 g/10 minutes, more preferably 2 to 13 g/10 minutes, and further preferably 3 to 11 g/10 minutes. It is preferable because it is excellent in mixing and dispersibility with the crystalline resin A, and the desired semi-transparency in the range of the total light transmittance is easily obtained. In the present invention, the melt mass flow rate of the amorphous resin B is measured according to JIS K 7210:1999 using a melt indexer manufactured by Toyo Seiki Seisakusho.

  Examples of the amorphous resin B include amorphous cyclic olefin copolymers such as copolymers of cyclic olefins and linear olefins, copolymerized polyester resins, polyethylene, polypropylene, polybutene, polymethylpentene, cyclopentadiene and the like. Such linear, branched or cyclic polyolefin resin, polyamide resin, polyimide resin, polyether resin, polyesteramide resin, polyetherester resin, acrylic resin, polyurethane resin, polycarbonate resin Examples thereof include polyvinyl chloride resin, polyacrylonitrile, polyphenylene sulfide, polystyrene, and fluorine resin. Among these, since the types of monomers to be copolymerized are diverse and the physical properties of the materials can be easily adjusted by the monomer types, amorphous cyclic olefin copolymers, copolymerized polyester resins, polyolefin resins, polyamides A resin, an acrylic resin, a mixture thereof, or the like is preferable. In particular, when an amorphous cyclic olefin copolymer is used, suitable voids are easily formed and a suitable total light transmittance is obtained, which is preferable. Although the reason is not always clear, the amorphous cyclic olefin copolymer has a small density ratio between the melt density and the solid density, and the resin shrinkability in the process from melt extrusion to cooling is significantly different from that of the crystalline resin A. Therefore, it is assumed that appropriate voids are easily formed, and as a result, suitable total light transmittance is easily obtained.

  As the amorphous resin B, these resins may be used alone, or two or more kinds of the amorphous resin B may be used in combination.

  The amorphous cyclic olefin copolymer is composed of at least one cyclic olefin selected from the group consisting of cycloalkene, bicycloalkene, tricycloalkene and tetracycloalkene, and linear olefin such as ethylene and propylene. It is a copolymer.

Examples of the cyclic olefin include bicyclo[2.2.1]hept-2-ene, 6-methylbicyclo[2.2.1]hept-2-ene and 5,6-dimethylbicyclo[2.2.1]hept. -2-ene, 1-methylbicyclo[2.2.1]hept-2-ene, 6-ethylbicyclo[2.2.1]hept-2-ene, 6-n-butylbicyclo[2.2. 1] hept-2-ene, 6-i-butylbicyclo[2.2.1]hept-2-ene, 7-methylbicyclo[2.2.1]hept-2-ene, tricyclo[4.3. 0.1 ^2.5 ]-3-decene, 2-methyl-tricyclo[4.3.0.1 ^2.5 ]-3-decene, 5-methyl-tricyclo[4.3.0.1 ^2.5 ] -3-decene, tricyclo ^[4.4.0.1 2.5] -3-decene, 10-methyl - tricyclo ^[4.4.0.1 2.5] -3-decene, tetracyclo [4. 4.0.1 ^2,5 . [ ^17,10 ] dodeca-3-ene and the like and their derivatives can be exemplified.

  The glass transition temperature of the amorphous cyclic olefin copolymer is, for example, by increasing the content of the cyclic olefin component in the cyclic olefin copolymer and decreasing the content of the linear olefin component such as ethylene, It can be adjusted within the range. Preferably, the content of the cyclic olefin component is 70 to 90% by mass, and the content of the linear olefin component such as ethylene is 30 to 10% by mass. More preferably, the content of the cyclic olefin component is 75 to 85% by mass, and the content of the linear olefin component such as ethylene is 25 to 15% by mass. More preferably, the content of the cyclic olefin component is 77 to 83% by mass, and the content of the linear olefin component such as ethylene is 23 to 17% by mass.

As the cyclic olefin, from the viewpoints of productivity, transparency, and easy increase in Tg, both bicyclo[2.2.1]hept-2-ene (bicyclo[2.2.1]hept-2-ene and norbornene are used. And its derivatives, tetracyclo[4.4.0.1 ^2,5 . [ ^17,10 ] Dodeca-3-ene (also referred to as tetracyclododecene) and its derivatives are preferable. From the viewpoint of reactivity, the linear olefin component is preferably at least one selected from the group consisting of ethylene, propylene and 1-butene, and more preferably ethylene.

  In addition to cyclic olefins and linear olefins, other copolymerizable unsaturated monomer components may be copolymerized, if necessary, within a range not impairing the object of the present invention. Such other copolymerizable unsaturated monomers may act as molecular weight regulators, examples being propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene. , 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and the like α-olefins having 3 to 20 carbon atoms, cyclopentene, cyclohexene, 3-methylcyclohexene, cyclooctene , 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-vinyl-2. -Norbornel, tetracyclododecene, 2-methyltetracyclododecene, 2-ethyltetracyclododecene and the like can be mentioned.

  Further, as the amorphous resin B, a hydrogenated product of an amorphous cyclic olefin copolymer can be used. Hydrogenated products in which almost all of the double bonds are saturated by hydrogenation are preferred because they provide improved resistance to heat and weathering. The hydrogenation rate of the hydrogenated product is preferably 90% or more, more preferably 99% or more.

  As the amorphous resin B, a commercially available one may be used. Typical commercial products include, for example, Topas Advanced Polymers GmbH Topas (registered trademark) 6015S-04, 6017S-04, 6013M-07, Mitsui Chemicals Co., Ltd. Apel (registered trademark) APL6015T, JSR Corporation JSR ARTON ( Registered trademark) F4520 and the like.

  The amorphous resin B is preferably 2% by mass or more, more preferably 2.5% by mass or more, still more preferably 4% by mass or more, still more preferably based on the total mass of the resin components contained in the base material layer. Can be used in an amount of 5% by mass or more, particularly preferably 6% by mass or more, and particularly preferably 7% by mass or more. The amorphous resin B is preferably 40% by mass or less, more preferably 35% by mass or less, still more preferably 25% by mass or less, and particularly preferably, based on the total mass of the resin components contained in the base material layer. It can be used in an amount of 15% by mass or less. The content of the amorphous resin B is 2.1 parts by mass or more, 2.5 parts by mass or more, 3 parts by mass or more, 4 parts by mass or more, 6.5 parts by mass with respect to 100 parts by mass of the crystalline resin A. As described above, 7.5 parts by mass or more are each preferable modes, and the content of the amorphous resin B is 67 parts by mass or less, 54 parts by mass or less, and 33 parts by mass with respect to 100 parts by mass of the crystalline resin A. Hereinafter, 18 parts by mass or less and the like are preferable embodiments. By using the amorphous resin B in the above range, it is easy to obtain desired total light transmittance and nonuniformity of whiteness such as texture of paper.

  The base material layer constituting the semitransparent stretched film of the present invention can be composed of two components, a crystalline resin A and an amorphous resin B, as resin components. In addition to the crystalline resin A and the amorphous resin B, the resin component of the base material layer constituting the semitransparent stretched film of the present invention is a crystalline thermoplastic resin C having a melting point of 200 to 280°C. (Hereinafter, referred to as crystalline resin C) can be further contained as a resin component (that is, the content of the crystalline resin C is 0% by mass based on the total mass of the resin component contained in the base material layer). May be present and may exceed 0% by mass). When the substrate layer of the semitransparent stretched film of the present invention contains the crystalline resin C in addition to the crystalline resin A and the amorphous resin B, the nonuniformity of whiteness such as the texture of paper is further increased. It is easier to obtain and, as a result, easier to use as a substitute for paper. When the substrate layer of the semitransparent stretched film of the present invention does not contain the crystalline resin C, it is a preferable aspect from the viewpoint of total light transmittance (semitransparency), printability and pencil writing property.

  The melting point of the crystalline resin C is preferably 200 to 280°C, more preferably 230 to 270°C, and further preferably 240 to 260°C. When the crystalline resin C having a melting point within the above range is used, it becomes easy to control the size of the fine dispersion of the crystalline resin C in the crystalline resin A during melt extrusion, and Since the deformation of the resin C is appropriately suppressed, the total light transmittance of the obtained stretched film is lowered, which makes it easy to obtain a stretched film having desired translucency, which is preferable.

  20-130 degreeC is preferable, as for the glass transition temperature of crystalline resin C, 60-120 degreeC is more preferable, and 80-110 degreeC is further more preferable. When the glass transition temperature of the crystalline resin C having a melting point within the above range is used, if the crystalline resin A and the amorphous resin B have a specific glass transition temperature as described above, the film may be stretched. At this time, a suitable void portion can be formed between the interfaces of the crystalline resin A, the amorphous resin B, and the crystalline resin C, which is preferable. Further, the productivity of the stretched film and the heat resistance, flexibility, low temperature brittleness and the like of the obtained stretched film are favorable, which is preferable.

  In the present invention, the melting point and the glass transition temperature of the crystalline resin C were measured using an input compensation type DSC, Diamond DSC manufactured by Perkin-Elmer.

  The crystalline resin C has a melt mass flow rate at 300° C. and 1.2 kg or 260° C. and 5 kg of preferably 1 to 60 g/10 minutes, more preferably 1 to 40 g/10 minutes, and further preferably 5 to 35 g/10 minutes. And particularly preferably 10 to 20 g/10 minutes. When the melt mass flow rate is within the above range, it is preferable because the mixing property with the crystalline resin A and the amorphous resin B and the dispersibility are excellent, and the desired semi-transparency in the range of the total light transmittance is easily obtained. In the present invention, the melt mass flow rate of the crystalline resin C was measured using a melt indexer manufactured by Toyo Seiki Seisakusho Co., Ltd. according to JIS K 7210:1999.

  The crystalline resin C is not particularly limited as long as it is a crystalline thermoplastic resin C having a melting point of 200 to 280° C., for example, crystalline polystyrene resin, crystalline polycarbonate resin, polyphenylene sulfide resin, polymethylpentene resin. (A resin containing 4-methylpentene-1 as a main constituent unit), and crystalline polyamide resins and crystalline polyester resins having a melting point of 200 to 280° C. and the like. Among these, the dispersibility in the crystalline resin A is moderate and easy to control to the desired total light transmittance, and the excellent resistance to water, acids, alkalis, salts and the like is also used for food packaging applications and the like. A crystalline polyester-based resin, a polymethylpentene resin, a crystalline polystyrene-based resin and the like having a melting point of 200 to 280° C. are preferable because they are easy.

  In particular, when a crystalline polystyrene resin is used, preferable total light transmittance can be obtained, which is preferable. Although the reason is not always clear, although the crystalline polystyrene resin is a resin having the above-mentioned preferable melting point and preferably the above-mentioned glass transition temperature, the specific gravity thereof is generally not so high as 1.05 or less. Therefore, it is presumed that the volume occupied in the crystalline resin A and the amorphous resin B becomes moderately large, and as a result, a suitable total light transmittance can be easily obtained.

  As the crystalline resin C, the above resins may be used alone, or two or more crystalline resins C may be used in combination. By using two or more kinds of the crystalline resin C in combination, the size of the fine dispersion of the crystalline resin C in the crystalline resin A, the amount of the crystalline resin A, the amorphous resin B and the crystalline resin C The size of the voids generated between the interfaces is likely to vary, and as a result, uneven whiteness such as the texture of the paper is likely to be obtained.

Examples of the crystalline polycarbonate resin, for example, the formula: _{[- O-Ph-C (CH} 3) 2 -Ph-O-C (= O) - ] wherein the repeating unit represented by the DSC measurement of the above Polycarbonate resins whose melting points are observed are mentioned. Here, Ph, 2 divalent phenylene group - shows a _(-C 6 _{H 4).}

  Examples of the crystalline polyamide resin include ring-opening polymerization type aliphatic polyamide, polycondensation type polyamide, semi-aromatic polyamide and amide type elastomer. A so-called nylon 66 (PA66) resin synthesized by a polycondensation reaction of hexamethylenediamine and adipic acid is preferable because it has an appropriate melting point and can obtain translucency in a desired total light transmittance range. Also, nylon 6 (PA6) or the like can be used.

  As the polyphenylene sulfide resin, the specific gravity measured according to ASTM-D792 is preferably 1.4 or less, and the tensile modulus measured according to ASTM-D638 is preferably 3.5 GPa or less. It is easy to obtain a desired semi-transparency in the range of the total light transmittance.

  As the polymethylpentene resin, the tensile elastic modulus measured at 23° C. according to ASTM-D638 is preferably 1.8 GPa or more, and the Vicat softening temperature measured according to ASTM-D1525 is preferably 165° C. or more. It is more preferable that the temperature is 170° C. or higher, because it is easy to obtain the desired semi-transparency in the range of the total light transmittance. Examples of typical commercial products of the polymethylpentene resin include TPX (registered trademark) DX845, DX231, DX820, RT18, RT31 manufactured by Mitsui Chemicals, Inc.

  Examples of the crystalline polyester resin include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethylene terephthalate, and the like. The crystalline polyester resins may be used alone or in admixture of two or more. In particular, as the crystalline polyester resin, among the copolymerization components, those having an acid component containing terephthalic acid as a main component and a diol component containing ethylene glycol as a main component are preferable. The main components, terephthalic acid and ethylene glycol, are contained in the acid component and the diol component in a proportion of 51 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more. The crystalline polyester resin may contain 49 mol% or less, preferably 30 mol% or less, more preferably 20 mol% or less of other copolymerization components in the acid component and/or the diol component.

  Examples of the other copolymerizable acid component include isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, 4,4-stilbenedicarboxylic acid, 4,4-biphenyl. Dicarboxylic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bisbenzoic acid, bis(p-carboxyphenyl)methane, anthracene dicarboxylic acid, 4,4-diphenyl ether dicarboxylic acid, 4,4 -Aromatic dicarboxylic acids such as diphenoxyethanedicarboxylic acid, 5-Na sulfoisophthalic acid, ethylene-bis-p-benzoic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1,3-cyclohexanedicarboxylic acid And aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid. Of these, aromatic dicarboxylic acids such as isophthalic acid and 2,6-naphthalenedicarboxylic acid are preferable.

  Examples of the other copolymerizable diol components include diethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, trans-tetramethyl- 1,3-cyclobutanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, decamethylene glycol, 1,4-cyclohexanediol, 1,3-cyclohexanediol, spiroglycol, p-xylenediol, bisphenol A, tetrabromobisphenol A, Examples include diols such as tetrabromobisphenol A-bis(2-hydroxyethyl ether). Among these, diethylene glycol and 1,3-propanediol are preferable.

  These crystalline polyester resins may be used alone or in combination of two or more. Examples of commercially available crystalline polyester resins include Novapex (registered trademark) series manufactured by Mitsubishi Chemical Co., Ltd., TR-8550FF manufactured by Teijin Ltd., and the like.

  The structure of the crystalline polystyrene-based resin may be either an isotactic structure or a syndiotactic structure, but as the crystalline polystyrene-based resin, a crystalline polystyrene-based resin having a syndiotactic structure is mainly used. Is preferred. In the present invention, the syndiotactic structure means that the stereochemical structure is a syndiotactic structure, that is, a phenyl group or a substituted phenyl group, which is a side chain with respect to the main chain formed from carbon-carbon bonds, alternates in opposite directions. It refers to one having a three-dimensional structure located.

The tacticity of the crystalline polystyrene resin can be quantified by a nuclear magnetic resonance method ( ¹³ C-NMR method) using isotope carbon. ^The tacticity measured by the ¹³ C-NMR method can be indicated by the abundance ratio of a plurality of continuous constitutional units, for example, diad in the case of two, triad in the case of 3, and pentad in the case of 5. .. The polystyrene resin B used in the present invention is usually 75% or more, preferably 85% or more in racemic diad, or 60% or more, preferably 75% or more in racemic triad, or 30% or more, preferably 50% in racemic pentad. It is a styrenic polymer having a syndiotacticity of at least %.

  The types of crystalline polystyrene resins include styrene homopolymer (polystyrene), poly(alkylstyrene), poly(halogenated styrene), poly(halogenated alkylstyrene), poly(alkoxystyrene), poly(vinylbenzoic acid). Ester), hydrogenated polymers thereof and mixtures thereof, and copolymers containing them as a main component.

  As poly(alkylstyrene), poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tertiarybutylstyrene), poly(phenylstyrene), poly(vinylnaphthalene), poly(vinylstyrene) ) And the like. Examples of poly(halogenated styrene) include poly(chlorostyrene), poly(bromostyrene) and poly(fluorostyrene). Examples of the poly(halogenated alkylstyrene) include poly(chloromethylstyrene). Examples of poly(alkoxystyrene) include poly(methoxystyrene) and poly(ethoxystyrene).

  As the comonomer component of the copolymer containing these structural units, in addition to the monomers of the styrene-based polymer, olefin monomers such as ethylene, propylene, butene, hexene and octene, diene monomers such as butadiene and isoprene, and cyclic olefin monomers. , Polar vinyl monomers such as cyclic diene monomer, methyl methacrylate, maleic anhydride, and acrylonitrile. Preferred styrene-based polymers include polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tertiarybutylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene). ), poly(p-fluorostyrene), hydrogenated polystyrene and copolymers containing these structural units. Specific examples of the copolymer include a styrene-butyl acrylate copolymer, a styrene-conjugated diene block copolymer, and a hydrogenated product of a styrene-conjugated diene block copolymer. Or a mixture of two or more kinds may be used. Examples of the conjugated diene include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene and the like.

  The crystalline polystyrene-based resin is preferably a resin obtained by copolymerizing at least styrene as a styrene-based monomer and p-methylstyrene, and the content of p-methylstyrene in the styrene-based monomer is 1 to 30 mol%. It is preferably present, and more preferably 3 to 15 mol %. By setting the content of p-methylstyrene in the styrene-based monomer within the above range, it becomes easy to control the size of the fine dispersion of the polystyrene-based resin in the crystalline resin A. Therefore, the total light transmittance of the stretched film can be reduced to a desired range. Further, the flexibility of the film is also suitable, and the stretchability is improved so that breakage or the like is less likely to occur.

  The molecular weight of the crystalline polystyrene resin used in the present invention is not particularly limited, but the weight average molecular weight is preferably 10,000 or more, more preferably 50,000 or more. When the weight average molecular weight is 10,000 or more, the thermal properties and mechanical strength of the obtained stretched film can be improved. In addition, the upper limit of the molecular weight of the polystyrene resin used in the present invention is preferably 3,000,000, and more preferably 1,500,000 from the viewpoint of mixing with the crystalline resin A and dispersibility.

  According to JIS K 7210:1999, the crystalline polystyrene resin has a melt mass flow rate measured at 300° C. and 1.2 kg of preferably 1 to 40 g/10 minutes, more preferably 10 to 35 g/10 minutes. .. By setting the melt mass flow rate within the above range, it becomes easy to control the size of the fine dispersion of the crystalline resin C in the crystalline resin A. Therefore, it becomes easy to obtain a desired total light transmittance.

  In the present invention, the crystalline polystyrene resin may be a known one, for example, a resin produced by a method of polymerizing styrene as a monomer using a metallocene catalyst, or a commercially available resin. .. Examples of typical commercial products include Zarek (registered trademark) 142ZE, Zarek (registered trademark) 300ZC, Zarek (registered trademark) 130ZC, and Zarek (registered trademark) 90ZC manufactured by Idemitsu Kosan Co., Ltd. These crystalline polystyrene resins may be used alone or in combination of two or more.

  When the crystalline thermoplastic resin C is used in the base material layer, the total content of the amorphous thermoplastic resin B and the crystalline thermoplastic resin C is preferably 4 based on the total mass of the resin components of the base material layer. ˜35% by mass, more preferably 5 to 25% by mass, further preferably 6 to 20% by mass, particularly preferably 7 to 15% by mass, particularly preferably 10 to 15% by mass. When the total content of the amorphous thermoplastic resin B and the crystalline thermoplastic resin C is in the above range, desired total light transmittance and nonuniformity of whiteness such as texture of paper are easily obtained, Further, the stretchability can be improved and the occurrence of breakage can be suppressed.

  In the base material layer, in addition to the crystalline resin A, the amorphous resin B and the crystalline resin C, a resin component other than the crystalline resin A, the amorphous resin B and the crystalline resin C, a melting point and a glass different from those of the crystalline resin A, the amorphous resin B and the crystalline resin C are used. A crystalline resin and/or an amorphous resin exhibiting a transition temperature (hereinafter, also referred to as other resin R) may be adjusted for stretchability, low temperature impact resistance, surface roughness, rigidity, strength, and elongation. For the purpose of adjusting various physical properties such as the above, it may be contained within a range that does not impair the effects of the present invention.

  The other resin R is not particularly limited, and conventionally known resins that are suitable for stretched film applications can be appropriately used in the present invention. Examples of the other resin R include polyolefin resins such as polyethylene, polypropylene, poly(1-butene), polyisobutene, poly(1-pentene), and polymethylpentene, and copolymer resins thereof such as ethylene-propylene. Examples thereof include copolymers of α-olefins such as copolymers, propylene-butene copolymers and ethylene-butene copolymers. In addition, styrene-based resins, vinyl-based resins, polyester-based resins, polyurethane-based resins, nylon-based resins and copolymers thereof, for example, vinyl monomer-diene monomer copolymers such as styrene-butadiene copolymer , Vinyl monomers such as styrene-butadiene-styrene copolymer-diene monomer-vinyl monomer copolymer and the like.

  When another resin R is used for the base material layer, the content of such another resin R is preferably 15% by mass or less based on the total mass of the resin components contained in the base material layer. It is more preferable that the content is not more than mass %. The lower limit of the content of the other resin R is not particularly limited, but is, for example, 0% by mass or 1% by mass.

The base material layer may contain an additive as an optional component in addition to the resin component, if necessary. Examples of the additives include heat stabilizers, antioxidants, organic and inorganic lubricants, chlorine scavengers, antistatic agents and the like. Such additives can be used in an amount that does not impair the effects of the present invention.
As described above, the translucent stretched film of the present invention has the texture of paper even if it does not contain an inorganic substance such as calcium carbonate. Therefore, in order not to impede the above-mentioned characteristics of the present invention, an inorganic substance in the base material layer is 1 mass% or less, 0.5 mass% or less, 0.1 mass% or less, 0.01 mass% or less of the total mass of the base material layer. Alternatively, it is preferably 0% by mass (containing no inorganic substance).

  Examples of heat stabilizers and antioxidants include phenol-based, hindered amine-based, phosphite-based, lactone-based, and tocopherol-based heat stabilizers and antioxidants. More specifically, dibutyl hydroxytoluene, pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] ("Irganox (registered trademark) 1010" manufactured by BASF Japan Ltd.), 1,3,5-Trimethyl-2,4,6-tris(3,5-di-t-butyl-4hydroxy)benzene ("Irganox (registered trademark) 1330" manufactured by BASF Japan Ltd.), Tris(2, 4-di-t-butylphenyl) phosphite ("Irgafos (registered trademark) 168" manufactured by BASF Japan Ltd.) and the like can be mentioned. Among these, at least one selected from the phenolic antioxidant system or a combination thereof, or a combination of a phenolic system and a phosphite system, a phenolic system and a lactone system, a phenolic system, a phosphite system and a lactone system. Is preferable from the viewpoint of imparting chemical stability to the film.

  Examples of the lubricant include organic lubricants and inorganic lubricants. Examples of the organic lubricant include stearic acid amide, aliphatic amide such as erucic acid amide, lauric acid diethanolamide, alkyldiethanolamine, aliphatic monoglyceride, aliphatic diglyceride, and silicone crosslinked polymer. Examples of the inorganic lubricant include silica and alumina. Organic lubricants are preferable in that the printing plates are less likely to be contaminated in printing applications.

  Examples of chlorine scavengers include calcium stearate, metal soaps, hydrotalcite and the like.

Examples of the antistatic agent include alkylmethyldibetaine, alkylamine diethanol and/or alkylamine ethanol ester and/or alkylamine diethanol diester. Among these, two or more kinds of antistatic agents may be used in combination, and an aliphatic alcohol may be used in combination.
Among them, it is preferable to use stearyldiethanolamine monostearate in combination with stearyldiethanolamine, since the antistatic performance is excellent and the printability is improved.
Examples of typical commercially available antistatic agents include Electrostriper series manufactured by Kao Corporation.

  Next, the surface layer will be described. The surface layer contains at least a crystalline thermoplastic resin D (hereinafter, referred to as crystalline resin D) having a melt mass flow rate of 0.02 to 2 g/10 minutes at 190° C. and 2.16 kg as a resin component. In the present invention, the melt mass flow rate of the crystalline resin D was measured using a melt indexer manufactured by Toyo Seiki Seisakusho Co., Ltd. according to JIS K 7210:1999.

  The crystalline resin D has a melt mass flow rate at 190° C. and 2.16 kg of 0.02 to 2 g/10 minutes, preferably 0.02 to 1.5 g/10 minutes, and more preferably 0.02 to 1 g/minute. It is 10 minutes, more preferably 0.03 to 0.5 g/10 minutes, and particularly preferably 0.03 to 0.1 g/10 minutes. If the melt mass flow rate of the crystalline resin D at 190° C. and 2.16 kg is less than 0.02 g/10 minutes, fish eyes are generated and the appearance of the film is deteriorated. Further, when the melt mass flow rate at 190° C. and 2.16 kg exceeds 2 g/10 minutes, roughening becomes insufficient, and as a result, a suitable matte appearance cannot be obtained. As the crystalline resin D, a crystalline resin D having a melt mass flow rate of 0.02 to 0.1 g/10 min at 190° C. and 2.16 kg and a crystalline resin D of 0.11 to 1.5 g/10 min. Is a preferred embodiment from the viewpoint of printability and pencil writability, and the crystalline resin D of 0.03 to 0.1 g/10 minutes and the crystalline resin D of 0.11 to 1 g/10 minutes. Is a more preferred embodiment.

  The melting point of the crystalline resin D is not particularly limited, but is preferably 100°C to 160°C.

Examples of the crystalline resin D include a crystalline polyethylene resin, a crystalline polypropylene resin, a crystalline polystyrene resin, and the like, and these can be used alone or in combination of two or more kinds. Among these, from the viewpoint of printability and pencil writability, it is preferable to use a crystalline polyethylene resin as the crystalline resin D, and it is more preferable that the crystalline resin D is a crystalline polyethylene resin. The crystalline polyethylene resin is preferably at least one selected from the group consisting of high-density polyethylene (HDPE), medium-density polyethylene (MDPE) and low-density polyethylene (LDPE), and comprises high-density polyethylene and low-density polyethylene. At least one selected from the group is more preferable, and two kinds of high-density polyethylene and low-density polyethylene are more preferable. By using these two types in combination, it is easy to improve the glossiness and printability, which is preferable. Here, the high-density polyethylene, density refers to 0.942 g · ^{cm -3} or more polyethylene (preferably 0.942 g · ^{cm -3} or more 0.965 g · ^{cm -3} or less of polyethylene), and medium density polyethylene a density of say a 0.930 g · ^{cm -3} or more 0.942 g · ^{cm -3} than polyethylene (preferably 0.930 g · ^{cm -3} or more 0.941 g · ^{cm -3} or less of polyethylene), low density polyethylene Means 0.910 g·cm ⁻³ or more and less than 0.930 g·cm ⁻³ (preferably 0.910 g·cm ⁻³ or more and 0.929 g·cm ⁻³ or less polyethylene). As used herein, low density polyethylene includes linear low density polyethylene. Linear low-density polyethylene is a copolymer of ethylene and one or more α-olefins selected from α-olefins having 3 to 20 carbon atoms, and as a α-olefin having 3 to 20 carbon atoms, Include propylene, 1-butene, 1-pentene, 4-methyl 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and the like. As the linear low-density polyethylene, a metallocene-catalyzed linear low-density polyethylene that is polymerized with a metallocene catalyst and exhibits a sharper molecular weight distribution than a conventional catalyst (Ziegler-Natta catalyst) may be used.

  As the crystalline resin D, a commercially available one may be used. Typical commercial products include, for example, Hi-Zex (registered trademark) 7000F, Hi-Zex (registered trademark) 3300F manufactured by Prime Polymer Co., Ltd., Novatec (registered trademark) HF111K manufactured by Japan Polypro Co., Novatec (registered trademark) HE30, Novatec (registered trademark). Trademark) LF280 and the like.

  In addition to the crystalline resin D, the surface layer may further contain a crystalline thermoplastic resin A'(hereinafter also referred to as a crystalline resin A') as a resin component. When the surface layer contains the crystalline resin A', the fluidity of the resin component is improved, and the film of the present invention having a paper-like appearance and a stable thickness can be more suitably obtained. Examples of such crystalline resin A'include the same resins as the crystalline resin A that can be used for the base material layer. Specific (i) type of resin component of crystalline thermoplastic resin A′, (ii) melt mass flow rate, (iii) melting point, (iv) glass transition temperature, (v) above (i) to (iv), etc. All the description of the preferred embodiments of the above is the same as the above (i) to (v) of the crystalline resin A described in the description of the base material layer. Therefore, the description including the above (i) to (v) of the crystalline thermoplastic resin A'is omitted here. The crystalline thermoplastic resin A′ may be used alone or in combination of two or more kinds of resin components. The crystalline resin A′ used in the surface layer and the crystalline resin A used in the base material layer may be the same type of resin in combination, or different types of resin may be used. ..

Further, the surface layer includes, in addition to the crystalline resin D (and optionally the crystalline resin A′), an amorphous thermoplastic resin B′ (hereinafter, also referred to as an amorphous resin B′) and/or a crystalline thermal resin. A plastic resin C'(hereinafter, also referred to as a crystalline resin C') may be contained as a resin component. When the amorphous resin B′ and/or the crystalline resin C′ is contained as the resin component of the surface layer, the desired total light transmittance and the nonuniformity of whiteness such as the texture of paper are more suitably obtained. .. Examples of the amorphous resin B′ and the crystalline resin C′ include the same resins as the amorphous resin B and the crystalline resin C that can be used for the base material layer. Specific (i) types of resin components of amorphous resin B'and crystalline resin C', (ii) melt mass flow rate, (iii) melting point (in the case of crystalline resin C'), (iv) glass transition For all explanations of temperature, (v) preferred embodiments such as (i) to (iv), etc., the above (i) of the amorphous resin B and the crystalline resin C described above in the description of the base material layer, respectively. )-(V) and the like. Therefore, the description of the amorphous resin B′ and the crystalline resin C′ including the above (i) to (v) is omitted here. Each of the amorphous resin B′ and the crystalline resin C′ may be used alone or in combination of two or more kinds of resin components.
The amorphous resin B′ used in the surface layer and the amorphous resin B used in the base material layer may be the same type of resin in combination, or different types of resins may be used. Good. The crystalline resin C′ used in the surface layer and the crystalline resin C used in the base material layer may be the same type of resin in combination, or different types of resins may be used. Good.

  The content of the crystalline resin D in the surface layer is preferably 1 to 60% by mass, more preferably 1 to 50% by mass, and further preferably 5 to 50% by mass, based on the total mass of the resin components of the surface layer. 15 to 45 mass% is even more preferable, and 35 to 45 mass% is particularly preferable. When the content of the crystalline resin D in the surface layer is within the above range, the surface of the film is appropriately roughened and a matting effect is obtained.

When the surface layer contains the crystalline resin A′, the content of the crystalline resin A′ in the surface layer is preferably 40 to 99% by mass, more preferably based on the total mass of the resin component of the surface layer. 45 to 95% by mass, more preferably 45 to 90% by mass, even more preferably 45 to 80% by mass, and particularly preferably 45 to 65% by mass. When the content of the crystalline resin A'in the surface layer is within the above range, the stretchability is excellent and the roughening is sufficient, which is preferable. When the surface layer contains the crystalline resin A′, the mass ratio of the contents of the crystalline resin D and the crystalline resin A′ is as follows: crystalline resin D:crystalline resin A′=1:99 to 60:40. Is preferred, 5:95 to 50:50 is more preferred, 15:85 to 45:55 is further preferred, 25:75=45:55 is even more preferred, and 35:65 to 45:55 is particularly preferred. When the crystalline resin A′ is contained, the content of the crystalline resin A′ contained in the surface layer and the content of the crystalline resin A contained in the base layer may be the same or different. May be.

When the surface layer contains the amorphous resin B′ and/or the crystalline resin C′, the total content of the amorphous resin B′ and/or the crystalline resin C′ in the surface layer is equal to that of the surface layer. It is preferably 5 to 30% by mass, more preferably 7 to 28% by mass, and further preferably 9 to 26% by mass, based on the total mass of the resin component. When the total content of the amorphous resin B'and/or the crystalline resin C'in the surface layer is within the above range, the desired total light transmittance and the non-uniformity of whiteness such as the texture of paper are desired. Is more easily obtained, and roughening is improved, and as a result, occurrence of breakage and the like can be suppressed.
When the surface layer contains the amorphous resin B′, the content of the amorphous resin B′ contained in the surface layer and the content of the amorphous resin B contained in the base layer are the same. It may be different or different. When the surface layer contains the crystalline resin C′, the content of the crystalline resin C′ contained in the surface layer and the content of the crystalline resin C contained in the base layer are the same. It may be different or different.

  In the surface layer, in addition to the crystalline resin D, and optionally the crystalline resin A′, the amorphous resin B′ and/or the crystalline resin C′, the crystalline resin D, and optionally a crystal used as a resin component. Other resin R'having a melting point or glass transition temperature different from that of the crystalline resin A', the amorphous resin B and the crystalline resin C'is adjusted for the stretchability, the low temperature impact resistance, and the surface roughness. For the purpose of adjustment, adjustment of various physical properties such as rigidity, strength, and elongation, they may be contained within a range that does not impair the effects of the present invention.

  As the other resin R′, those exemplified as the other resin R used for the base material layer can be used.

  When another resin R'is used for the surface layer, the content of such another resin R'is preferably 35% by mass or less based on the total mass of the resin components contained in the surface layer, 30 It is more preferable that the content is not more than mass %. The lower limit of the content of the other resin R′ is not particularly limited, but is, for example, 0% by mass or 1% by mass.

In addition to the resin component, the surface layer may optionally contain additives such as a heat stabilizer, an antioxidant, an organic and inorganic lubricant, a chlorine scavenger, and an antistatic agent as optional components. Good. Such additives can be used in an amount that does not impair the effects of the present invention. As the additive that can be used in the surface layer, the additives exemplified as the additive that can be used in the base material layer can be used.
As described above, the translucent stretched film of the present invention has the texture of paper even if it does not contain an inorganic substance such as calcium carbonate. Therefore, in order not to impede the above-mentioned characteristics of the present invention, an inorganic substance in the surface layer is 1% by mass or less, 0.5% by mass or less, 0.1% by mass or less, 0.01% by mass or less or 0% by mass or less of the total mass of the surface layer. It is preferably set to mass% (does not contain an inorganic substance) or the like.

The density of the semitransparent stretched film of the present invention is preferably 0.65 to 0.95 g/cm ³ , more preferably 0.72 to 0.92 g/cm ³ , and further preferably 0.76 to 0. was 90 g / cm ^3, particularly preferably 0.80~0.88g / cm ^3. When the density is within the above range, translucency within a desired range of total light transmittance is easily obtained, which is preferable. When the density is 0.65 g/cm ³ or more, the breaking strength and the intralayer peel strength can be easily improved, and the present film can be suitably used for packaging applications and the like. The density of the semitransparent stretched film of the present invention is an apparent density defined in 3.3 of JIS K 7222:2005, and is measured according to the standard.

  The translucent stretched film of the present invention is obtained, for example, by blending the crystalline resin A and the amorphous resin B together with the crystalline resin C, other resin R and/or additives, etc., if necessary. A resin composition for forming a base material layer (hereinafter, also referred to as a resin composition for a base material layer) and a crystalline resin D, if necessary, a crystalline resin A′, an amorphous resin B′, and a crystalline resin C. ', another resin R', and/or a resin composition for forming a surface layer obtained by blending with an additive and the like (hereinafter, also referred to as a resin composition for a surface layer) is extrusion-molded and biaxially stretched It can be manufactured.

  Examples of the blending method for preparing the resin composition for the base layer and the resin composition for the surface layer include a dry blending method and a melt blending method. For example, in the case of preparing a resin composition for a base material layer, in the dry blending method, pellets or powders of the crystalline resin A and the amorphous resin B may be mixed with the crystalline resin C or another resin R if necessary. Dry blending is carried out with a pellet or powder and/or an additive using a batch type mixing device such as a tumbler or a mixer, or a continuous metering type mixing device. In addition, for example, in the case of preparing a resin composition for a base material layer, in the melt blending method, pellets or powders of the crystalline resin A and the amorphous resin B, and the crystalline resin C and other resins are used as necessary. It is supplied to a kneading machine together with the pellets and powder of R and/or additives, and melt-kneaded to obtain a melt-blended resin composition. The case of preparing the resin composition for the surface layer is also the same as the case of the resin composition for the base material layer.

  As a kneading machine used for melt kneading, a known kneading machine can be used. For example, a single-screw type, a twin-screw type, or a multi-screw type of more than that can be used. Further, in the case of a screw type having two or more screws, either a kneading type rotating in the same direction or a different direction can be used. In the present invention, a twin-screw type kneader rotating in the same direction is preferable because the size of the fine dispersion can be easily controlled.

  The kneading temperature for melt kneading is preferably in the range of 220 to 300°C, more preferably in the range of 230 to 280°C. By setting the temperature range to the above range, the size of the fine dispersion of the amorphous resin B in the crystalline resin A and the crystalline resin C in some cases is controlled, and the amorphous resin in the crystalline resin A′ is adjusted in some cases. It is preferable because the size of the fine dispersion of B′ and/or the crystalline resin C′ can be controlled, and as a result, a desired total light transmittance can be obtained. An inert gas such as nitrogen may be purged to prevent deterioration of the resin during melt-kneading.

  The melt-kneaded resin can be pelletized to an appropriate size by using a generally known granulator to obtain a pellet-shaped melt-blended resin composition.

  The dry blend resin composition and/or the melt blend resin composition of the resin composition for a base layer and/or the resin composition for a surface layer obtained as described above is supplied to an extruder, melted by heating, and then filtered. After removing fine foreign matters and the like by a method such as the above, it can be melt-extruded into a sheet form from a T-die.

  There is no limitation on the screw type of the extruder, and a single screw type, a twin screw type, or a multi-screw type of more than that can be used. When the resin blending method is dry blending, a twin screw type or a multi-screw type having more than two screws is preferable because of excellent mixing performance and dispersion performance.

  The extrusion temperature is preferably in the range of 220 to 300°C, more preferably in the range of 230 to 290°C. In order to prevent thermal deterioration of the resin during extrusion, an inert gas such as nitrogen may be purged.

  As a laminating method for obtaining the laminated film, a conventionally known method such as a coextrusion method, a laminating method or a heat sealing method can be used. Therefore, the laminated film of the present invention may be a multilayer film obtained by co-extruding the resin composition for the base layer and the resin composition for the surface layer, and laminating and stretching the resin composition, and the stretched film of the present invention May be a laminate with the film, a multilayer unstretched film obtained by sticking the unstretched film of the substrate layer and the surface layer extruded as a single layer to each other (the substrate layer may be a plurality, The type of the base material layer may be different or the same) and may be a multilayer film obtained by stretching.

  Examples of the co-extrusion method include a die pre-laminating method in which a molten resin is brought into contact in a feed block in front of a die, an intra-die laminating method in which a die, for example, a path inside a multi-manifold die is brought into contact, and discharge from concentric circular lips And the die outer laminating method in which they are brought into contact with each other. The translucent stretched film of the present invention has, for example, a two-layer structure of a b layer/a layer consisting of a surface layer (b layer) and a base material layer (a layer), and a b base layer/a having two base material layers Layer/a layer or a three-layer structure of b layer/a layer/b layer in which two surface layers are formed, and b layer/a layer/c layer in which one surface layer is another layer (c layer) Three-layer structure, four-layer structure of b layer/a layer/a layer/c layer with two base material layers, and one of the two base material layers is another base material layer. It is possible to have a four-layer structure such as b layer/a layer/a' layer/c layer which is (a' layer).

  For example, in the case of a two-layer structure of b layer/a layer, the mass ratio b:a of the resin composition for the surface layer used for the extruded b layer and the resin composition for the base layer used for the a layer is preferably 1: It is 9 to 9:1, more preferably 1:9 to 3:7. In the case of a three-layer structure of b layer/a layer/c layer, for example, the resin composition for the surface layer used for the extruded b layer, the resin composition for the base layer used for the a layer, and the resin composition used for the c layer. The mass ratio b:a:c of the substance is preferably 1:8:1 to 8:1:1, more preferably 1:8:1 to 3:6:1.

  The extruded base material layer is in a state in which the amorphous resin B is dispersed in the crystalline resin A in various sizes. As a result, the voids formed around the amorphous resin B in the subsequent stretching step have various sizes, and a partial difference occurs in the transmittance, resulting in uneven whiteness such as the texture of paper. Will be obtained.

  Examples of the laminating method include an extrusion laminating method in which equipment for a melt extrusion molding method used in the T-die method is used and a film of a molten resin is directly extruded onto another film to form a laminated film.

  The heat-sealing method includes an external heating method in which a heated metal body is pressed from the outside of the film to a plurality of laminated films, and the conducted heat melts and bonds the film, and heat is applied to the film by high-frequency radio waves or ultrasonic waves. An internal heat generation method for generating and joining is mentioned.

  In the present invention, the above stacking methods can be used alone or in combination.

When the base material layer is composed of two or more layers, the crystalline resin A used in each base material layer may be the same kind of resin in combination, or different kinds of resins may be used. Alternatively, the content of the crystalline resin A in each base material layer may be the same or different. This also applies to the amorphous resin B and/or the crystalline resin C used in each base material layer when the base material layer is composed of two or more layers. When the types and/or the contents thereof are different, for example, it is easy to obtain a desired total light transmittance in a layer containing a large amount of the amorphous resin B and the crystalline thermoplastic resin C in the base material layer, It is possible to improve both the quality and the productivity by improving the stretchability of the layer having a small content.
In addition, when the surface layer is two or more layers and each surface layer contains the crystalline resin A′, the crystalline resin A′ used in each surface layer may be the same kind of resin in combination. Good or different types of resins may be used, and the content of the crystalline resin A′ in each surface layer may be the same or different. This is because when the surface layer is two or more layers and each surface layer contains the amorphous resin B′ and/or the crystalline resin C′, the amorphous resin B′ and/or the crystalline resin used in each surface layer is used. The same applies to the resin C′.

The extruded resin sheet is formed into a sheet by, for example, a known method in which at least one metal drum set to a temperature of 25° C. or higher and lower than 120° C. is brought into close contact with an air knife, another roll, or static electricity. It is formed into a raw sheet.
When the temperature of the metal drum is within the above range, it is possible to control the crystal growth of the crystalline resin A, the crystalline resin C and the crystalline resin D, and in some cases, the crystalline resin A′ and/or the crystalline resin C′. It becomes possible, the deformation at the time of stretching is suppressed, and the desired total light transmittance is easily obtained. The more preferable temperature of the metal drum is 30 to 100°C, and the more preferable temperature is 40 to 70°C.

  As a stretching method for obtaining the translucent stretched film of the present invention, a known method such as a method of stretching between rolls having a peripheral speed difference, a tenter method, a tubular method or the like can be used. The stretching direction may be uniaxial stretching, biaxial stretching, oblique biaxial stretching, or the like, and in biaxial or more stretching, either sequential stretching or simultaneous stretching is applicable. Among these, from the viewpoint that a film having a uniform total light transmittance is easily obtained, a simultaneous biaxial stretching method by a tenter method, a sequential biaxial stretching method by a tenter method, and a longitudinal direction between rolls provided with a peripheral speed difference (flow, A sequential biaxial stretching method in which MD (MD) stretching is followed by transverse (width, TD) stretching by a tenter method is preferable.

Stretching is usually performed so that the film temperature (Ts) is between the melting point Tm(A) and the glass transition temperature Tg(A) of the crystalline resin A which is the main resin among the crystalline resins A contained in the base material layer. So that the temperature becomes Here, the main resin means a resin having the largest content of the crystalline resins A contained in the base material layer (for example, corresponds to A1 in Example 1). Further, here, the film temperature Ts is the temperature of the film at the time when the film is started to be stretched, but when the film temperature in each stage is different in multistage stretching such as sequential biaxial stretching, the lowest film among them is used. Let temperature be Ts.
In addition, when Ts is equal to or lower than the glass transition temperature Tg(B) of the amorphous resin B contained in the base material layer, the amorphous resin B cannot be deformed during stretching, and the amorphous resin B and the amorphous resin B cannot be deformed. The size of the void formed between the interface with the resin B is likely to be different, and the nonuniformity of whiteness such as the texture of paper is easily obtained.
Therefore, in the present invention, the following relational expression:
Tm(A)>Tg(B)>Ts>Tg(A)
By satisfying the above condition, a semitransparent stretched film having a desired total light transmittance and a nonuniformity of whiteness such as the texture of paper can be obtained, which is preferable.

  It is preferable that Ts is lower than Tg(B) by 3° C. or more, and more preferably lower than Tg(B) by 5° C. to 30° C., because a semitransparent film exhibiting a desired total light transmittance can be easily obtained.

  As the sequential biaxial stretching method, it is necessary to adjust the stretching temperature and the stretching ratio depending on the melting point and the glass transition temperature of the resin used, but first, the raw sheet is preferably 100 to 180°C, more preferably 120 to 170°C. The film temperature (Ts) is maintained, the film is passed between rolls provided with a peripheral speed difference, or by a tenter method in the longitudinal direction, preferably 2 to 10 times, more preferably 2.5 to 8 times, and further preferably It is stretched 3 to 6 times. Subsequently, the stretched film is subjected to a tenter method, preferably at a film temperature (Ts) of 100 to 180° C., more preferably 120 to 175° C., preferably 2 to 12 times in the transverse direction, more preferably 2.5 to After stretching 11.5 times, and more preferably 3 to 11 times, it is relaxed and heat set, and wound. If the temperature during stretching is increased, the total light transmittance tends to increase, and if the temperature is decreased, the total light transmittance tends to decrease.

  By stretching the film, voids of various sizes are formed around the amorphous resin B dispersed in the crystalline resin A in the base material layer and, in some cases, the surface layer. As a result, a partial difference occurs in the transmittance, and non-uniformity of whiteness such as the texture of paper is obtained. The amorphous resin B itself dispersed in the crystalline resin A is not in a hollow state but in a solid state (also referred to as a non-hollow state).

When the present film is used for packaging or the like, a heat seal layer may be laminated on one side and/or both sides of the present film, if necessary. That is, the semitransparent stretched film of the present invention may have a heat seal layer.
Preferably, the semitransparent stretched film of the present invention has a heat seal layer on the surface opposite to the surface layer. The surface opposite to the surface layer means, for example, the surface on the back surface side of the present film when the surface on which the surface layer is formed as viewed from the base material layer is the front surface of the film. ..

  The resin used for the heat-sealing layer is a thermoplastic resin having a melting point of 150° C. or lower, and is selected from α-olefin-based monomers having 2 to 10 carbon atoms such as ethylene, propylene, butene, pentene, hexene, octene and decene. Two or more kinds of random copolymers or block copolymers selected from the group consisting of are preferred. These copolymers can be used alone or as a mixture.

  Particularly preferred is a crystalline propylene-α-olefin random copolymer, and the α-olefin includes ethylene or an α-olefin having 4 to 20 carbon atoms, and the like. Ethylene, butene-1, hexene-1, octene. -1 or the like is preferably used, and a copolymer or terpolymer using ethylene or butylene is particularly preferably used. For example, a propylene-ethylene-butene random copolymer (FL6741G manufactured by Sumitomo Chemical Co., Ltd.) is preferable. An antiblocking agent such as acrylic resin-based fine particles or silica may be used in combination with the heat seal layer within a range that does not impair the effects of the present invention.

  The wound film is preferably subjected to aging treatment in an atmosphere of about 20 to 45° C. and then cut into a desired product width. Thus, a stretched film having excellent mechanical strength and rigidity can be obtained.

The film can be subjected to a corona treatment, a plasma treatment, a flame treatment or the like, if necessary, online or offline. In particular, when this film is used for printing, treatment such as corona treatment, plasma treatment, flame treatment, etc. is performed on one and/or both sides of this film for the purpose of spreading and spreading the printing ink and improving adhesion. Is preferably performed. In the present invention, the wetting tension of JIS K 6768:1999 on the film surface is preferably 36 to 45 mN/m, and more preferably 38 to 44 mN/m.
Alternatively, a printability imparting layer having the same wetting tension and also smoothness may be provided.

  In the semitransparent stretched film of the present invention, the surface layer has a 60-degree specular gloss of preferably 1 to 20%, more preferably 3 to 18%, further preferably 5 to 17%, particularly preferably 6 to 15%. When the 60-degree specular gloss is within the above range, the texture is paper-like and the visibility of printed characters and patterns is good, which is preferable. In the present invention, the 60-degree specular gloss is a value measured according to JIS Z 8741 (method 3).

  The semi-transparent stretched film of the present invention prevents problems such as contamination of packages due to falling off of inorganic substances, stains of printing plates for printing applications, rough cutting surfaces during cutting, and rapid wear of cutting blades. For burning, the ash content is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, based on the total mass of the film. The lower limit of the ash content is not particularly limited, but the lower the lower limit, the better, and it is, for example, 0.01 mass% or 0 mass%. In the present invention, the ash content can be measured according to the method A of JIS K 7250-1:2006.

  The thickness of the semitransparent stretched film of the present invention is preferably 10 to 150 μm, more preferably 15 to 100 μm, and still more preferably 20 to 60 μm, although it depends on its application. When the thickness of the film is 10 μm or more, sufficient strength is easily obtained. Further, when the thickness of the film is 150 μm or less, stretchability and productivity are excellent.

  When the thickness of the base material layer is 60 to 95% of the thickness of the semitransparent stretched film of the present invention, and the thickness of the surface layer is 5 to 40% of the thickness of the film, the desired total light transmittance is Also, whiteness nonuniformity such as the texture of paper tends to be easily obtained, and a matte appearance tends to be easily obtained.

  The semitransparent stretched film of the present invention preferably has pencil writing properties. Generally, a plastic film cannot be written with a pencil or the like because the film surface is too smooth, but in applications such as translucent paper, pencil writability is required. When the translucent stretched film of the present invention has pencil writing properties, it can be written in pencil like paper, even though it does not contain inorganic particles, and can be used for applications such as transparencies. Pencil writability is considered to be an effect achieved by appropriately roughening the surface.

  The semitransparent stretched film of the present invention preferably has heat sealability and/or printability. When the semitransparent stretched film of the present invention has heat sealability and/or printability, it can be preferably used for food packaging applications.

  The translucent stretched film of the present invention is used for packaging, food packaging, chemical packaging, decoration, labels, tape substrates, printing substrates, poster papers, thermal paper substrates, recording paper substrates, etc. Can be suitably used for.

  Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

[Resin melt mass flow rate (MFR)]
According to JIS K 7210:1999, it was measured using a melt indexer manufactured by Toyo Seiki Seisakusho. The crystalline resin A and the crystalline resin A′ were measured under the conditions of a measurement temperature of 230° C. and a load of 2.16 kg, and the amorphous resin B and the amorphous resin B′ were measured at a measurement temperature of 260° C. and a load of 2.16 kg. The crystalline resin C and the crystalline resin C′ were measured under the conditions of a measurement temperature of 300° C. and a load of 1.2 kg. The crystalline resin D was measured at a measurement temperature of 190° C. and a load of 2.16 kg.

[Resin melting point, glass transition temperature]
It was calculated by the following procedure using an input compensation type DSC and DiamondDSC manufactured by Perkin-Elmer. 5 mg of each resin was weighed, packed in an aluminum sample holder, and set in a DSC apparatus. Under nitrogen flow, the temperature was raised from -40°C to 300°C at a rate of 20°C/min, kept at 300°C for 5 minutes, cooled to -40°C at 20°C/min, and kept at -40°C for 5 minutes. After that, the melting point and the glass transition temperature were determined from the DSC curve when the temperature was raised again to 300° C. at 20° C./min. The melting point defined in 9.1(1) of JIS K 7121 (the maximum melting peak in the case of showing multiple melting peaks) is taken as the melting point, and the midpoint glass transition temperature defined in 9.3(1) of JIS K 7121 is used. The glass transition temperature was used.

[Film thickness]
It was measured according to JIS C 2330 using a paper thickness meter MEI-11 manufactured by Citizen Seimitsu Co., Ltd.

[Total light transmittance of film]
It was measured according to JIS K 7361 using a haze meter NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd.

[60 degree specular gloss of film]
Using a variable angle gloss meter GM-3D manufactured by Murakami Color Research Laboratory Co., Ltd., the 60-degree specular gloss was measured according to JIS Z 8741 (method 3). The measurement is a value obtained by measuring the film in the machine direction and in the machine direction and averaging both.

[Non-uniformity of whiteness]
The film was visually observed through the light of a fluorescent lamp and the degree of whiteness unevenness was evaluated as follows.
A: Whiteness has sufficient unevenness and can be used as a substitute for paper.
B: It has uneven whiteness and can be used as a substitute for paper.
C: Some whiteness unevenness is observed, but it is insufficient as a substitute for paper.
D: Whiteness is uniform and uniform.

[Ash content of film]
According to JIS-K7250-1 (2006)A method, the measurement sample amount was 200 g.

[Heat sealability evaluation method]
In an environment of 23° C. and 50% RH, heat-sealed heat sealer HG-100-2 (Toyo Corporation (Manufactured by Seiki Seisakusho Co., Ltd.), heat sealing treatment was performed under the conditions of a sealing temperature of 110° C., a sealing pressure of 200 KPa, a sealing time of 2 seconds, and a width of the heat sealing portion (corresponding to the MD direction of the film) of 1 cm. Next, the TD direction of the sample whose temperature was adjusted to 23° C. was cut into 25 mm. Then, using a tensile tester Technograph TGI-1kN (manufactured by Minebea Co., Ltd.), the ends of each of the two films were sandwiched between the upper and lower chucks and peeled at 180° at a pulling speed of 300 mm/min. The maximum value of the stress at that time was measured. The average value of the above three measurements was taken as the adhesive strength (N/25 mm) of the heat-sealed portion.
The adhesive strength was evaluated as follows.
A: 4 N or more and less than 6 N: The heat seal strength is appropriate and the unsealing property is excellent.
B: 6 N or more and less than 8 N: The heat seal strength is slightly strong, but the unsealing property is good enough for practical use.
C: 8 N or more: The heat seal strength is strong and there is a difficulty in opening.
D: Less than 4 N: Heat seal strength is weak and not practical.

[Printability evaluation method]
Four-color gravure printing was performed with a gravure rotary printing machine (OSG-550HDX manufactured by Orient Sogyo Co., Ltd.) using ink Ultima NT805 manufactured by DIC Graphics Co., Ltd. 5 gradations of 100%, 90%, 80%, 70%, and 60% are printed for each of the four colors of CMYK, and the printed part (4 colors x 20 gradations of 5 gradations) is visually observed and evaluated as follows. did.
A: No dot omission was observed in any of the cells, and moreover, it was printed clearly, which is very good.
B: No dot omission was observed in any of the cells, which is good.
C: There are 1 or more and 6 or less cells with missing dots, but there is no practical problem.
D: There are 7 or more and 12 or less cells with missing dots, which is not preferable in practice.
E: There are 13 or more cells with missing dots, which is not practical.

[Pencil writing]
Each film was written with a pencil of HB, and the written state was evaluated according to the following criteria.
A: It is written clearly and darkly, and it is very excellent in writability.
B: Although inferior to the above evaluation A, it was written in a dark and clear manner, and was excellent in writability.
C: Writing is possible at a readable density, and there is no practical problem.
D: Writable, but thin and practically problematic.
E: I cannot write.

[Wet tension]
The wet tension of the film surface was measured one day after the stretched film was subjected to the corona treatment, and the surface subjected to the corona treatment was measured according to JIS K 6768:1999.

The following resins were used as crystalline resins A and/or A′ in the examples and comparative examples.
-Prime Polypro (registered trademark) F-300SP (hereinafter, also referred to as resin A1 or A'1): made by Prime Polymer Co., Ltd., crystalline propylene homopolymer, MFR at 230°C and 2.16 kg = 3 g/10 minutes, Melting point 160°C, glass transition temperature -7°C
-Wintec (registered trademark) WFW5T (hereinafter, also referred to as resin A2 or A'2): manufactured by Nippon Polypro Ltd., crystalline propylene-ethylene copolymer, MFR at 230°C and 2.16 kg = 3.5 g/10. Min, melting point 142°C, glass transition temperature -19°C

In the examples and comparative examples, the following resins were used as the amorphous resins B and/or B'.
Topas (registered trademark) 6015S-04 (hereinafter, also referred to as resin B1 or B′1): made by Topas Advanced Polymers GmbH, amorphous norbornene-ethylene copolymer, MFR at 260° C. and 2.16 kg=4.1 g. /10 minutes, glass transition temperature 158°C
Apel (registered trademark) APL6015T (hereinafter, also referred to as resin B2 or B′2): Mitsui Chemicals, Inc., amorphous tetracyclododecene-ethylene copolymer, MFR at 260° C. and 2.16 kg=10 g/ 10 minutes, glass transition temperature 145°C
Topas (registered trademark) 6013M-07 (hereinafter, also referred to as resin B3 or B′3): an amorphous norbornene-ethylene copolymer manufactured by Topas Advanced Polymers GmbH, MFR=14.3 g at 260° C. and 2.16 kg. /10 minutes, glass transition temperature 142°C

In the examples and comparative examples, the following resins were used as the crystalline resins C and/or C′.
-Zarek (registered trademark) 142ZE (hereinafter, also referred to as resin C1 or C'1): manufactured by Idemitsu Kosan Co., Ltd., polystyrene resin, MFR at 300°C and 1.2 kg = 14 g/10 minutes, melting point 247°C, glass transition temperature. 95°C

The following resins were used as the crystalline resin D in the examples and comparative examples.
-HIZEX (registered trademark) 7000F (hereinafter, also referred to as resin D1): made by Prime Polymer Co., Ltd., high-density polyethylene, MFR at 190°C and 2.16 kg = 0.04 g/10 minutes-Novatec (registered trademark) HF111K (hereinafter , Resin D2): High-density polyethylene manufactured by Japan Polyethylene Corporation, MFR at 190° C. and 2.16 kg=0.05 g/10 min. Novatec (registered trademark) HE30 (hereinafter, also referred to as resin D3): Japan polyethylene Ltd., low density polyethylene, MFR at 190° C. and 2.16 kg=0.30 g/10 min Novatec (registered trademark) LF280 (hereinafter, also referred to as resin D4): Nippon Polyethylene Co., Ltd., low density polyethylene, 190 MFR at 0.degree. C. and 2.16 kg=0.70 g/10 min

[Example 1]
Pellets of resin A1, resin A2 and resin B1 were dry blended in a mixer at the ratios shown in Table 1 to prepare a resin composition for a base layer. Further, the resin A′2 pellets and the resin D1 pellets were dry blended in a ratio shown in Table 1 with a mixer to prepare a surface layer resin composition.

  The base layer dry blend resin composition for forming the base layer is in a single screw type extruder a, and the surface layer dry blend resin composition for forming the surface layer is in a single screw type extruder b. Each of them is charged from a hopper and melted at 240° C., and these are extruded as a two-layer laminated resin layer in which two layers of a surface layer (b layer) and a base material layer (a layer) are laminated inside a two-layer multi-manifold die. It was The mass ratio of the amount of extruded resin between the single screw type extruder b and the single screw type extruder a was set to b:a=2:8. The resin sheet was solidified by cooling the extruded resin sheet while pressing the base material layer side of the extruded resin sheet on the cooling drum controlled at 45° C. with an air pressure using an air knife. Thus, a raw sheet was obtained.

  The obtained raw sheet was stretched using a batch type biaxial stretching machine KARO manufactured by Bruckner. The stretching method was a sequential biaxial stretching method of stretching in the machine direction and then in the transverse direction. The film temperature (Ts) was preheated to 138° C. in an oven at a set temperature of 158° C., and first stretched in the machine direction up to 4 times at a stretching speed of 6 times/sec. Next, in the same oven, the film temperature (Ts) was preheated to 141° C., and transversely stretched at a stretching speed of 1 time/second to 10 times. Next, in the same oven, the transverse direction was relaxed to 9.5 times at a relaxation rate of 0.5 times/second, then heat set for 10 seconds, discharged from the oven, cooled to room temperature, and stretched to a thickness of 30 μm. I got a film. Corona treatment was performed on the surface layer side of the obtained stretched film. The strength of the corona treatment was adjusted so that the wet tension of the treated surface one day after the treatment was 40 mN/m. Thereby, the stretched film of Example 1 was obtained.

[Example 2]
Regarding the surface layer, the same as in Example 1 except that 80% by mass of the resin A′2 and 20% by mass of the resin D1 were used instead of the ratio of the resin component forming the surface layer described in Example 1 above. The stretched film of Example 2 was obtained.

[Example 3]
Regarding the surface layer, the same as in Example 1 except that 70% by mass of the resin A′2 and 30% by mass of the resin D1 were used instead of the ratio of the resin component forming the surface layer described in Example 1 above. The stretched film of Example 3 was obtained.

[Example 4]
Regarding the surface layer, the same procedure as in Example 1 was carried out except that 80% by mass of the resin A′2 and 20% by mass of the resin D2 were used instead of the resin component and the ratio thereof constituting the surface layer described in Example 1 above. Similarly, a stretched film of Example 4 was obtained.

[Example 5]
With respect to the surface layer, 60% by mass of resin A′2, 20% by mass of resin D1 and 20% by mass of resin D3 were used instead of the resin component and the ratio thereof constituting the surface layer described in Example 1 above. A stretched film of Example 5 was obtained in the same manner as in Example 1 except for the above.

[Example 6]
Regarding the surface layer, in place of the resin component and the ratio thereof constituting the surface layer described in Example 1 above, the resin A′2 is 50% by mass, the resin B′1 is 10% by mass, and the resin D1 is 20% by mass. And a stretched film of Example 6 was obtained in the same manner as in Example 1 except that 20% by mass of Resin D3 was used.

[Example 7]
Regarding the surface layer, in place of the resin component and the ratio thereof constituting the surface layer described in the above Example 1, 50% by mass of resin A′2, 10% by mass of resin B′3, and 20% by mass of resin D1. A stretched film of Example 7 was obtained in the same manner as in Example 1 except that 20% by mass of Resin D3 was used.

[Example 8]
Regarding the surface layer, 60% by mass of the resin A′2, 20% by mass of the resin D1 and 20% by mass of the resin D4 were used instead of the resin component and the ratio thereof constituting the surface layer described in Example 1 above. A stretched film of Example 8 was obtained in the same manner as in Example 1 except for the above.

[Example 9]
Regarding the base material layer, 83 mass% of the resin A1, 3.5 mass% of the resin A2, and 5.5 mass% of the resin B1 are used instead of the resin component and the ratio thereof constituting the base material layer described in Example 1 above. % And 8% by mass of resin C1. Regarding the surface layer, 20% by mass of the resin D1 and 80% by mass of the resin A′2 were used instead of the resin component and the ratio thereof constituting the surface layer described in Example 1 above. Regarding the melting temperature, the base layer dry blend resin composition and the surface layer dry blend resin composition were melted at 280°C instead of 240°C. Other than the above (except for the above), a stretched film of Example 9 was obtained in the same manner as in Example 1.

[Example 10]
Regarding the base material layer, 83 mass% of the resin A1, 3.5 mass% of the resin A2, and 13.5 mass% of the resin B1 were used instead of the resin component and the ratio thereof constituting the base material layer described in Example 1 above. Mass% was used. Further, regarding the surface layer, in place of the resin component and the ratio thereof constituting the surface layer described in Example 1 above, the resin D1 is 24.3% by mass, the resin A′2 is 65.7% by mass, and the resin B. '1 was used at 10 mass %. Other than the above (except for the above), the stretched film of Example 10 was obtained in the same manner as in Example 1.

[Example 11]
Regarding the base material layer, 83 mass% of the resin A1, 3.5 mass% of the resin A2, and 13.5 mass% of the resin B1 were used instead of the resin component and the ratio thereof constituting the base material layer described in Example 1 above. Mass% was used. Further, regarding the surface layer, in place of the resin component constituting the surface layer described in Example 1 and the ratio thereof, 20 mass% of resin D1, 55 mass% of resin A′2, and 25 mass% of resin C′1 were used. Mass% was used. Regarding the melting temperature, the base layer dry blend resin composition and the surface layer dry blend resin composition were melted at 280°C instead of 240°C. Other than the above (except for the above), the stretched film of Example 11 was obtained in the same manner as in Example 1.

[Example 12]
Regarding the base material layer, in place of the resin component and the ratio thereof constituting the base material layer described in Example 1 above, in the base material layer, 83 mass% of the resin A1, 3.5 mass% of the resin A2 and 3.5 mass% of the resin B2 were used. 13.5 mass% was used. Further, regarding the surface layer, 20 mass% of resin D1, 55 mass% of resin A′2, and 25 mass% of resin C′1 were used. Regarding the melting temperature, the base layer dry blend resin composition and the surface layer dry blend resin composition were melted at 280°C instead of 240°C. Other than the above (except for the above), the stretched film of Example 12 was obtained in the same manner as in Example 1. The density of Example 12 was 0.89 g/cm ³ .

[Example 13]
Pellets of resin A1, resin A2, resin B2, and resin C1 were each dry-blended with a mixer at a ratio shown in Table 1 to prepare a resin composition for a base layer. Further, the resin A′2, resin B′1, resin C′1 and resin D1 pellets were dry-blended in a mixer at the ratios shown in Table 1 to prepare a surface layer resin composition.

  As a resin for the heat seal layer, 90 parts by mass of a propylene-ethylene-butene random copolymer (Sumitomo Chemical Co., Ltd. Sumitomo Noblene (registered trademark) FL6741G), and a propylene-butene copolymer (Mitsui Chemicals Tuffmer (trademark ) XM-7070) 10 parts by mass and 0.2 parts by mass of amorphous silica (Silysia 730 manufactured by Fuji Silysia Chemical Ltd.) as an anti-blocking agent are dry blended with a mixer to prepare a resin composition for a heat seal layer. did.

  The base layer dry blend resin composition for forming the base layer is in a single screw type extruder a, and the surface layer dry blend resin composition for forming the surface layer is in a single screw type extruder b. The resin composition for a heat-sealing layer for forming the heat-sealing layer was put into a single screw type extruder HS from each hopper and melted at 280°C. These were extruded in a three-layer multi-manifold die as a three-layer resin layer having a three-layer structure of a surface layer (b layer)-base material layer (a layer)-heat seal layer (HS). The mass ratio of the extruded resin amounts of the single screw type extruder b, the single screw type extruder a and the single screw type extruder HS was set to 2:7:1. The heat-sealing layer side of the extruded resin sheet was solidified by cooling it while pressing it against the cooling drum controlled at 45° C. with an air pressure using an air knife. Thereby, a raw sheet was obtained.

The obtained raw sheet was stretched and corona-treated in the same manner as in Example 1 to obtain a stretched film of Example 13. The density of Example 13 was 0.84 g/cm ³ .

[Example 14]
Regarding the base material layer, 92 mass% of the resin A1, 5 mass% of the resin A2 and 3 mass% of the resin B1 were used in place of the resin component and the ratio thereof constituting the base material layer described in Example 1 above. Regarding the surface layer, in place of the resin component and the ratio thereof constituting the surface layer described in the above Example 1, 50% by mass of resin A′2, 10% by mass of resin B′3, and 20% by mass of resin D1. A stretched film of Example 14 was obtained in the same manner as in Example 1 except that 20% by mass of Resin D3 was used.

[Comparative Example 1]
Regarding the base material layer, resin A1 was used alone without dry blending and melt-kneading, instead of the resin component and the ratio thereof constituting the base material layer described in Example 1 above. Regarding the layer structure of the film, instead of laminating the two-layer structure of the surface layer (b layer)-base material layer (a layer) in Example 1 above, the base layer was formed without forming the surface layer (b layer). Only the material layer (a layer) was formed. A stretched film of Comparative Example 1 was obtained in the same manner as in Example 1 except for the above (other than the above). The density of Comparative Example 1 was 0.97 g/cm ³ .

[Comparative Example 2]
Regarding the layer structure of the film, the base material without preparing the surface layer (b layer) in place of the two-layer structure of the surface layer (b layer)-base material layer (a layer) in Example 1 described above. A stretched film of Comparative Example 2 was obtained in the same manner as in Example 1 except that only the layer (layer a) was prepared.

[Comparative Example 3]
Regarding the surface layer, in place of the resin component and the ratio thereof constituting the surface layer described in Example 1 above, pellets of the resin A′2 were used alone without performing dry blending and melt mixing. A stretched film of Comparative Example 3 was obtained in the same manner as in Example 1.

[Comparative Example 4]
Regarding the substrate layer, instead of the resin component and the ratio thereof constituting the surface layer described in Example 1 above, Resin A1 was used alone without dry blending and melt mixing. Regarding the surface layer, 20% by mass of resin D1 and 80% by mass of resin A′2 were used instead of the resin component and the ratio thereof constituting the base material layer described in Example 1 above. A stretched film of Comparative Example 4 was obtained in the same manner as in Example 1 except for the above (other than the above).

Tables 1 and 2 below show the measurement and evaluation results of the stretched films obtained in each example, together with the composition of the resin used for each stretched film. In the printability of Table 2, - ^** means that a stretched film having both low glossiness and nonuniformity of whiteness could not be obtained, and therefore evaluation was not performed.

As shown in Tables 1 and 2, the stretched films of Examples 1 to 14 were translucent stretched films having extremely low gloss and a total light transmittance of 35 to 85%. Further, these films had printability and pencil writability even if they had no inorganic pigment (inorganic particles). Therefore, the translucent stretched film of the present invention is a film having excellent moisture resistance, water resistance, oil resistance, and mechanical strength as compared with paper, but has a moderate translucency and a low glossiness so that It is understood that it can be used as a substitute for paper due to its excellent texture and printability and pencil writing property.
Further, since the stretched film of Example 13 also has a heat-sealing property, it can be understood that the stretched film can be suitably used for a packaging form or the like that requires heat-sealing property of foods such as bread.

  On the other hand, in Comparative Example 1 in which the crystalline resin A was used as the sole component in the base material layer and the surface layer was not formed, only a transparent film having no whiteness nonuniformity and high glossiness was used. I couldn't get it. Further, in Comparative Example 2 in which the surface layer was not formed, translucency and non-uniformity of whiteness were obtained, but a stretched film having a high glossiness and a matte appearance could not be obtained. Furthermore, even in Comparative Example 3 in which the crystalline resin A was used as the sole component without using the crystalline resin D in the surface layer, translucency and nonuniformity of whiteness were obtained, but the glossiness was high, No stretched film with a matte appearance was obtained. Further, in Comparative Example 4 in which the amorphous resin B was not used in the base material layer, non-uniformity of whiteness was not obtained. That is, the films obtained in Comparative Examples 1 to 4 did not show a paper-like appearance.

Claims (6)

A translucent stretched film comprising at least a base material layer and a surface layer,
The base material layer has at least one layer containing at least a crystalline thermoplastic resin A having a melting point of 120 to 175° C. and an amorphous thermoplastic resin B as resin components,
The surface layer contains at least a crystalline thermoplastic resin D having a melt mass flow rate of 0.02 to 2 g/10 minutes at 190° C. and 2.16 kg as a resin component, and a total light transmittance of 35 to 85%. There is a semitransparent stretched film.   The semitransparent stretched film according to claim 1, wherein the amorphous thermoplastic resin B has a glass transition temperature of 135 to 185°C.   The translucent stretched film according to claim 1 or 2, wherein the base material layer further contains a crystalline thermoplastic resin C having a melting point of 200 to 280°C as a resin component.   The semitransparent stretched film according to claim 1, wherein the surface layer further contains a crystalline thermoplastic resin A′ as a resin component.   The translucent stretched film according to any one of claims 1 to 4, which has a heat-sealing layer on the surface opposite to the surface on which the surface layer is laminated.   The semitransparent stretched film according to claim 1, wherein the surface layer side has a 60-degree specular gloss of 1 to 20%.