JP2017213868A - Translucent stretched film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a translucent stretched film having matte appearance, preferably a translucent stretched film which has excellent printability and heat sealability and optionally has pencil writing properties.SOLUTION: There is provided a translucent stretched film having a total light transmittance of 35 to 85% which contains at least a substrate layer and a surface layer, wherein the substrate layer has one or more layers containing at least a crystalline thermoplastic resin A having a melting point of 120 to 175°C and a crystalline thermoplastic resin C having a melting point of 200 to 280°C as resin components and the surface layer contains at least a crystalline thermoplastic resin D having a melt mass flow rate of 0.02 to 2 g/10 min as measured at 190°C and 2.16 kg as a resin component.SELECTED DRAWING: None

Description

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

  Conventionally, translucent paper such as translucent paper, glassine paper, paraffin paper, and sulfuric acid paper has 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 and the like. However, these translucent papers lose their translucency when the thickness is increased, and the mechanical strength becomes insufficient when the thickness is reduced. Also, paper dust is generated during printing, cutting, packaging, and the like, which may cause problems such as deterioration in printability and cutting workability, and contamination of the package. Further, compared to plastic films, the moisture resistance, water resistance and oil resistance are low, and it may not be used for packaging of foods containing moisture and oil. Furthermore, paper generally does not have heat sealability and cannot be used in packaging forms that require heat sealability.

  On the other hand, plastic films are excellent in moisture resistance, water resistance and oil resistance, and have good mechanical strength, so that they are used for wrapping paper for foods and medicines. However, plastic films are highly transparent, and unless printed on the entire surface, it is difficult to visually recognize characters, pictures, etc. In addition, since the texture is uniform, it is difficult to obtain a high-class feeling and design. For this reason, the plastic film has a problem that it is difficult to attract the attention of consumers.

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

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

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

  Patent Document 3 discloses an opaque polymer film including a polymer matrix and a base layer including a solid, non-hollow particle cavitation agent comprising a syndiotactic polystyrene polymer, and at least one additional layer. Proposed. Patent Document 3 describes that an ethylene norborene copolymer is further contained as a cavitation agent in the polymer film.

JP-A-11-005852 JP-A-8-73618 Special table 2003-522504 gazette

However, with respect to 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 dropping off of the particles, and the printing plate may be soiled for printing, and the cutting workability is not good.
Regarding the above-mentioned Patent Document 2, the opaque polyolefin film is a single-layer film of crystalline olefin and cyclic olefin resin, so that it has a glossy appearance and does not have a paper-like texture and has a writing property with a pencil or the like. It is not to be.
Furthermore, the polymer film described in Patent Document 3 is opaque and does not have translucency. Moreover, the surface layer having a matte effect is not described, and the polymer film does not have a paper-like texture.

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

  As a result of intensive studies, the present inventors have found that the appearance of paper in a translucent stretched film is related to surface side gloss (glossiness) and non-uniformity of whiteness due to the base material layer. I found it. The inventors are a translucent stretched film including at least a base material layer and a surface layer, and the base material layer has a crystalline thermoplastic resin A having a melting point of 120 to 175 ° C., and a melting point. It has at least one layer containing at least 200 to 280 ° C. crystalline thermoplastic resin C as a resin component, and the surface layer has a melt mass flow rate at 190 ° C. and 2.16 kg of 0.02 to 2 g / 10 min. It has been found that the above-mentioned problems can be solved by a translucent stretched film having a total light transmittance of 35 to 85%, which contains at least the crystalline thermoplastic resin D as a resin component, and has completed the present invention.

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

The translucent stretched film of the present invention is white and translucent, and has excellent mechanical strength, moisture resistance, water resistance and oil resistance, so that it can be used for labels, tape substrates, printing substrates, poster papers, It can be suitably used for a thermal paper base, a recording paper base, and the like. In addition, it has a non-uniform whiteness and a matte appearance, like paper texture, and therefore has a paper texture (paper-like appearance), which makes it easy to use as a substitute for paper. .
In addition, in order to obtain a matte appearance, the surface can be appropriately roughened so that pencil writing can be performed like paper.

The translucent stretched film of the present invention has a paper texture even if it does not contain inorganic particles. In such an embodiment, there is no contamination of the package due to dropping off of the inorganic particles or contamination of the printing plate in printing applications, and problems such as rough cutting surfaces and rapid cutting blade consumption do not occur during cutting.
Furthermore, in a certain embodiment of this invention, since the translucent stretched film of this invention has the outstanding printability and heat-sealability, it can be preferably used for a food packaging use.

  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 ranges.

The present invention is a translucent stretched film including at least a base material layer and a surface layer, and the base material layer has a crystalline thermoplastic resin A (hereinafter referred to as crystalline resin A) having a melting point of 120 to 175 ° C. And at least one layer containing at least a crystalline thermoplastic resin C having a melting point of 200 to 280 ° C. (hereinafter also referred to as crystalline resin C) as a resin component. And a translucent stretched film having a total light transmittance of 35 to 85%, containing at least a crystalline thermoplastic resin D having a melt mass flow rate of 0.02 to 2 g / 10 min at 2.16 kg as a resin component . The translucent stretched film of the present invention includes at least a base material layer and a surface layer, and is composed of a plurality of layers.
Here, the crystalline thermoplastic resin is heated at a rate of 20 ° C./min from −40 ° C. to 300 ° C. under a nitrogen flow using DSC, held at 300 ° C. for 5 minutes, and at 20 ° C./min. A thermoplastic resin that exhibits a clear melting peak in the DSC curve when it is cooled to -40 ° C, held at -40 ° C for 5 minutes, and then heated again to 300 ° C at 20 ° C / min.
Moreover, the non-crystalline thermoplastic resin mentioned later 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 a crystalline thermoplastic resin C having a melting point of 200 to 280 ° C. as resin components” May include one or a plurality of layers as a layer constituting the substrate layer, the substrate layer containing at least the crystalline resin A and the crystalline resin C as resin components (using the resin A and C together). In other words, the base material layer includes a layer containing at least the crystalline resin A and the crystalline resin C as resin components (the resin A and C are used in combination). It does not mean to have as a layer.

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 crystalline resin C 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, the base material layer contains at least the crystalline resin A and the crystalline resin C as resin components (the resin A). 1 and C) may be a single layer or a plurality of layers.
When the base layer of the translucent stretched film contains the crystalline resin A and the crystalline resin C, the dispersed state of the crystalline resin C in the crystalline resin A and the voids formed around it are provided. By having various sizes, a partial difference occurs in the transmittance, and non-uniformity in whiteness such as a paper texture is obtained. Moreover, the surface layer which has a matte external appearance is obtained by containing the crystalline thermoplastic resin D whose melt mass flow rate is in the said range in a surface layer. By combining such a base material layer and a surface layer, a translucent stretched film having a translucent paper-like appearance can be obtained. The crystalline resin C itself in the base layer of the translucent stretched film is not in a hollow state but in a solid state (or a non-hollow state).

  The translucent stretched film of the present invention has a total light transmittance of 35 to 85%. When 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, if it exceeds 85%, the transparency becomes too high, and the visibility of characters and designs printed on the film surface deteriorates. The translucent stretched film of the present invention preferably has a total light transmittance of 40% to 80%, more preferably 50% to 75%, and still more preferably 52 to 70%. If the total light transmittance is within the above range, the stretched film is preferably translucent. 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, still more preferably 130 to 164 ° C, and particularly preferably 135 to 163 ° C. When the melting point of the crystalline resin A is less 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 is difficult to control the size of the fine dispersion of the crystalline resin C in the crystalline resin A.

  The glass transition temperature of the crystalline resin A is preferably 50 ° C. or lower, and more preferably −30 ° C. to 30 ° C. When the glass transition temperature of the crystalline resin A satisfies the above requirements and the crystalline resin C has a specific glass transition temperature as described later, when the film is stretched, the crystalline resin A and the crystalline resin C It is preferable because a moderate void can be formed between the interfaces. Moreover, since the productivity of a stretched film, the heat resistance of the stretched film obtained, a softness | flexibility, low temperature brittleness, etc. become favorable, it is preferable.

  In the present invention, the melting point and glass transition temperature of the crystalline resin A were measured using an input compensation DSC and Diamond DSC 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, still more preferably 2 to 6 g / 10 minutes, particularly Preferably it is 2.5-6 g / 10min. By setting the melt mass flow rate within the above range, the fluidity of the resin becomes an appropriate range, and a stretched film can be produced with a precise thickness. Moreover, it becomes easy to control the size of the fine dispersion of the crystalline resin C in the crystalline resin A, and a desired total light transmittance is easily obtained. In the present invention, the melt mass flow rate of the crystalline resin A was measured using a melt indexer manufactured by Toyo Seiki Seisakusho, in accordance with JIS K 7210: 1999. Here, the fine dispersion itself of the crystalline resin C 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 Examples of the polyamide-based resin include those having a melting point of 120 to 175 ° C. These can be used alone or in admixture of two or more. Of these, crystalline polyolefin resins are preferred, and in particular, crystalline polyolefin resins exhibiting the melting point and preferably the glass transition temperature of the crystalline resin A described above are excellent in stretchability and desired at an appropriate film stretching temperature. Since it becomes easy to obtain the translucent stretched film which shows the total light transmittance of this, it is preferable.

  As the crystalline polyolefin 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. A homopolymer, a copolymer, etc. are mentioned, These can be used individually or as a 2 or more types of mixture. Among these, crystalline polypropylene-based resins are preferable, particularly from the group consisting of crystalline propylene homopolymers and copolymers of crystalline propylene and ethylene (hereinafter also referred to as crystalline propylene-ethylene copolymers). At least one selected is preferred. 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 for the crystalline resin A, there is a tendency that the cracking property at a low temperature of the film is improved and the surface glossiness is easily lowered.

  Therefore, as the crystalline resin A, only a crystalline propylene homopolymer is used, or a mixture of a crystalline propylene homopolymer and a copolymer of propylene and ethylene and / or another polymer is used. Or only a copolymer of propylene and ethylene and / or other polymers can be used. Moreover, the crystalline resin A can also use properly the kind of resin used by a layer according to the quality requested | required. 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 a copolymer of propylene and ethylene. Crystalline polyester resin, crystalline polyamide resin, crystalline acetal resin and the like may be used. Preferably, the crystalline resin A is used in combination of two components of a crystalline propylene homopolymer and a crystalline propylene-ethylene copolymer. In this case, the preferred 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, and 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 the degree of stereoregularity determined by high temperature nuclear magnetic resonance (NMR) measurement, preferably 90 to 98%. Yes, more preferably 91-95%. When the mesopentad fraction [mmmm] is 90% or more, the crystallinity of the resin is improved by the high stereoregularity 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 is improved.

The high temperature NMR apparatus for measuring the mesopentad fraction ([mmmm]) is not particularly limited, and is generally a commercially available high temperature nuclear magnetic resonance (NMR) apparatus capable of measuring the degree of 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 (ODCB: ODCB and deuterated ODCB mixed solvent (volume mixing ratio = 4/1)) is used as the solvent. The method by high temperature NMR can be performed by a known method, for example, a method described in “Japan Analytical Chemistry / Polymer Analysis Research Roundtable, New Edition Polymer Analysis Handbook, Kinokuniya, 1995, p. 610”. . The measurement mode is a single pulse proton broadband decoupling, a pulse width of 9.1 μsec (45 ° pulse), a pulse interval of 5.5 sec, an integration count of 4500 times, and a shift reference is CH ₃ (mmmm) = 21.7 ppm.

  The pentad fraction representing the degree of stereoregularity is a combination of a pentad of a consensus “meso (m)” arranged in the same direction and a consensus “rasemo (r)” arranged in the same direction (mmmm or mrrm). Etc.) is calculated as a percentage from the integrated intensity value of each signal derived from. Regarding the attribution of each signal derived from mmmm, mrrm, etc., the description of the spectrum such as “T. Hayashi et al., Polymer, 29, 138 (1988)” is referred to. 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, a known method such as a method of polymerizing propylene in a hydrocarbon solvent using a Ziegler catalyst system composed of titanium or an aluminum compound, a method of polymerizing in liquid propylene (bulk polymerization), a gas What was manufactured by the method etc. which superpose | polymerize in a phase can be used. Commercial products can also be used. Representative commercial products include, for example, those of the homopolymer of Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., PC412A manufactured by Sun Allomer Co., Ltd., Novatec (registered trademark) series manufactured by Nippon Polypro Corporation. Among them, homopolymers, Borealis Daploy series, Korean Oil Chemical Co., Ltd. 5014L series, Sumitomo Chemical Co., Ltd. Sumitomo Nobrene (registered trademark) series, and so on.

  As the copolymer of crystalline propylene and ethylene, both 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 is contained in the copolymer. What is contained in is more preferable. Representative commercial products include, for example, those of the Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., those of the Novatec (registered trademark) series manufactured by Nippon Polypro Co., Ltd., and Win Among the Tech (registered trademark) series and Sumitomo Chemical Co., Ltd. Sumitomo Noblen (registered trademark) series, there may be mentioned copolymers.

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

  Examples of the crystalline acetal resin include homopolymers such as polyoxymethylene resins and polyoxyethylene resins, and copolymers thereof. These crystalline acetal resins can be used alone or in admixture of two or more.

  The crystalline resin A is preferably used in an amount of 65 to 96% by mass, more preferably 75 to 94% by mass, and still more preferably 85 to 93% by mass based on the total mass of the resin components contained in the base material layer. be able to. For example, when the base material layer includes two or more layers containing the crystalline resin A and the crystalline resin C, all of the resin components contained in the layer containing the crystalline resin A and the crystalline resin C are included. It is preferable that the mass% of the crystalline resin A is within the above range in each layer based on the mass. By using the crystalline resin A in the above range, a film excellent in stretchability and mechanical strength can be easily obtained.

  Next, the crystalline resin C will be described. The crystalline resin C has a melting point of 200 to 280 ° C, preferably 210 to 270 ° C, more preferably 220 to 270 ° C, still more preferably 220 to 260 ° C, still more preferably 230 to 260 ° C, particularly preferably. It is 230-250 degreeC, More preferably, it is 240-250 degreeC. If the melting point of the crystalline resin C is 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 during the melt extrusion, and the crystalline resin C Since deformation is moderately suppressed, the total light transmittance of the obtained stretched film is lowered, and a stretched film having desired translucency is easily obtained, which is preferable.

  The glass transition temperature of the crystalline resin C is preferably 20 to 130 ° C, more preferably 60 to 120 ° C, and still more preferably 80 to 110 ° C. 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 has a specific glass transition temperature as described above, the crystalline resin is stretched when the film is stretched. It is preferable because an appropriate gap can be formed between the interface between A and the crystalline resin C. Moreover, since the productivity of a stretched film, the heat resistance of the stretched film obtained, a softness | flexibility, low temperature brittleness, etc. become favorable, it is preferable.

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

  The crystalline resin C preferably has a melt mass flow rate at 300 ° C. and 1.2 kg or 260 ° C. and 5 kg, preferably 1 to 60 g / 10 minutes, more preferably 1 to 40 g / 10 minutes, still more preferably 5 to 35 g / 10 minutes. And particularly preferably 10 to 20 g / 10 min. When the melt mass flow rate is within the above range, it is preferable that the mixing property and dispersibility with the crystalline resin A are excellent, and translucency within a desired total light transmittance range 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 (Resin having 4-methylpentene-1 as a main structural unit), and those having a melting point of 200 to 280 ° C. among crystalline polyamide-based resins and crystalline polyester-based resins. Among these, the dispersibility in the crystalline resin A is moderate, it is easy to control the desired total light transmittance, and it is excellent in resistance to water, acid, alkali, salt, etc., so it is also used for food packaging applications. Since it is easy, crystalline polyester resin, polymethylpentene resin, crystalline polystyrene resin, etc. whose melting | fusing point is 200-280 degreeC are preferable.

  In particular, when a crystalline polystyrene resin is used, it is preferable because a suitable total light transmittance is obtained. The reason is not necessarily clear, but the crystalline polystyrene resin is generally not so high as a specific gravity of 1.05 or less in spite of the resin having the above-mentioned preferable melting point and preferably the above-mentioned glass transition temperature. For this reason, it is presumed that the volume occupied in the crystalline resin A is appropriately increased, and as a result, a suitable total light transmittance is 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 crystalline resins C in combination, the size of the fine dispersion of the crystalline resin C in the crystalline resin A and the voids generated between the interfaces of the crystalline resin A and the crystalline resin C As a result, it is easy to obtain non-uniformity in whiteness such as paper texture.

The crystalline polycarbonate resin includes, for example, a repeating unit represented by the formula: [—O—Ph—C (CH ₃ ) ₂ —Ph—O—C (═O) —]. A polycarbonate resin in which the melting point is observed can be mentioned. Here, Ph represents a divalent phenylene group (—C ₆ H ₄ —).

  Examples of the crystalline polyamide resin include ring-opening polymerization aliphatic polyamide, polycondensation polyamide, semi-aromatic polyamide, and amide 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 provides translucency within a desired total light transmittance range. Moreover, nylon 6 (PA6) etc. can also be used.

  The polyphenylene sulfide resin has a specific gravity measured in accordance with ASTM-D792 of preferably 1.4 or less, and a tensile modulus measured in accordance with ASTM-D638 of preferably 3.5 GPa or less. Translucency in the desired total light transmittance range is easily obtained.

  The polymethylpentene resin preferably has a tensile modulus measured at 23 ° C. in accordance with ASTM-D638 of 1.8 GPa or higher, and a Vicat softening temperature measured in accordance with ASTM-D1525 of preferably 165 ° C. or higher. More preferably, a material having a temperature of 170 ° C. or higher is preferable because it is easy to obtain translucency within the range of a desired total light transmittance. Examples of typical commercial products of polymethylpentene resin include TPX (registered trademark) DX845, DX231, DX820, RT18, RT31 and the like manufactured by Mitsui Chemicals.

  Examples of the crystalline polyester resin include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, and polycyclohexanedimethylene terephthalate. These crystalline polyester resins can be used alone or in admixture of two or more. In particular, as the crystalline polyester-based resin, among the copolymer components, it is preferable that the acid component has terephthalic acid as a main component and the diol component has ethylene glycol as a main component. The main components terephthalic acid and ethylene glycol are respectively 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. In addition, the crystalline polyester resin may contain 49 mol% or less, preferably 30 mol% or less, and more preferably 20 mol% or less of other copolymer components in the acid component and / or diol component.

  Examples of other copolymerizable acid components include isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, 4,4-stilbene dicarboxylic acid, and 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 Aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid And the like. Among 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, Tetrabromobisphenol A-bi (2-hydroxyethyl ether) diol, and the like. Of these, diethylene glycol and 1,3-propanediol are preferred.

  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 Corporation and TR-8550FF manufactured by Teijin Limited.

  The structure of the crystalline polystyrene resin may be either an isotactic structure or a syndiotactic structure, but a crystalline polystyrene resin mainly having a syndiotactic structure is used as the crystalline polystyrene resin. Is preferred. In the present invention, the syndiotactic structure is a syndiotactic structure, that is, phenyl groups and substituted phenyl groups that are side chains with respect to the main chain formed from carbon-carbon bonds are alternately reversed. It has a three-dimensional structure.

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 represented by the abundance ratio of a plurality of consecutive structural units, for example, a dyad for two, a triad for three, a pentad for five. . The polystyrene resin B used in the present invention is usually 75% or more, preferably 85% or more, or racemic triad, preferably 75% or more, preferably 75% or more, or 30% or more, preferably 50%, racemic pentad. It is a styrenic polymer having a syndiotacticity of at least%.

  Crystalline polystyrene resins include styrene homopolymer (polystyrene), poly (alkyl styrene), poly (halogenated styrene), poly (halogenated alkyl styrene), poly (alkoxy styrene), poly (vinyl benzoic acid). Esters), hydrogenated polymers thereof and mixtures thereof, and copolymers based on these.

  Poly (alkyl styrene) includes poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene), poly (phenyl styrene), poly (vinyl naphthalene), poly (vinyl styrene) ) And the like. Examples of poly (halogenated styrene) include poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene), and the like. Examples of 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 styrene polymer monomer, olefin monomers such as ethylene, propylene, butene, hexene, and octene, diene monomers such as butadiene and isoprene, and cyclic olefin monomers And polar vinyl monomers such as cyclic diene monomer, methyl methacrylate, maleic anhydride, and acrylonitrile. Preferred styrenic 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 styrene-butyl acrylate copolymer, styrene-conjugated diene block copolymer, and hydrogenated product of styrene-conjugated diene block copolymer. You may use it by mixing 2 or more types. Examples of the conjugated diene include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and the like.

  The crystalline polystyrene resin is preferably a resin obtained by copolymerizing at least styrene and p-methylstyrene as a styrene monomer, and the content of p-methylstyrene in the styrene monomer is 1 to 30 mol%. It is preferable that it is 3 to 15 mol%. By controlling the content of p-methylstyrene in the styrene monomer within the above range, the size of the fine dispersion of the polystyrene resin in the crystalline resin A can be easily controlled. Therefore, the total light transmittance of the stretched film can be lowered to a desired range. Furthermore, the flexibility of the film is also favorable, and the stretchability is improved, so that breakage and the like are 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. By setting the weight average molecular weight to 10,000 or more, the thermal properties and mechanical strength of the obtained stretched film can be improved. Moreover, the upper limit of the molecular weight of the polystyrene resin used in the present invention is preferably 3 million, more preferably 1.5 million, from the viewpoint of mixing and dispersibility with the crystalline resin A.

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

  In the present invention, the crystalline polystyrene resin may be one produced by a known method, for example, a method of polymerizing using styrene as a monomer and a metallocene catalyst, or a commercially available one. . Representative commercial products include, for example, 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.

  The content of the crystalline thermoplastic resin C in the base material layer is preferably 4 to 35% by mass, more preferably 5 to 25% by mass, and further preferably 6 to 20% based on the total mass of the resin components of the base material layer. It is preferably 7 to 15% by mass, particularly preferably 10 to 15% by mass. When the content of the crystalline thermoplastic resin C is within the above range, desired non-uniformity of whiteness such as desired total light transmittance and paper texture can be easily obtained, and stretchability is improved and breakage occurs. Etc. can be suppressed.

  In the base material layer, in addition to the crystalline resin A and the crystalline resin C, as a resin component, a crystalline resin having a melting point and a glass transition temperature different from those of the crystalline resin A and the crystalline resin C and / or Amorphous resins (hereinafter also referred to as other resins R) are used for the purpose of adjusting stretchability, adjusting low-temperature impact resistance, adjusting surface roughness, adjusting various physical properties such as stiffness, strength, and elongation. Further, it may be contained within a range not impairing the effects of the present invention.

  Other resins R are not particularly limited, and conventionally known resins that are suitable for stretched film applications can be used as appropriate in the present invention. Examples of other resins 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 include copolymers of α-olefins such as copolymers, propylene-butene copolymers, and ethylene-butene copolymers. Further, styrene resins, vinyl resins, polyester resins, polyurethane resins, nylon resins and copolymers thereof, for example, vinyl monomers-diene monomer copolymers such as styrene-butadiene copolymers. And vinyl monomer-diene monomer-vinyl monomer copolymer such as styrene-butadiene-styrene copolymer.

  When using other resin R for a base material layer, it is preferable that content of such other resin R is 15 mass% or less on the basis of the total mass of the resin component contained in a base material layer. It is more preferable that the amount is not more than mass%. Although the lower limit of content of other resin R is not specifically limited, For example, they are 0 mass%, 1 mass%, etc.

The base material layer may contain an additive as an optional component, if necessary, in addition to the resin component. Examples of the additive include a heat stabilizer, an antioxidant, an organic and inorganic lubricant, a chlorine scavenger, and an antistatic agent. Such additives can be used in amounts that do not impair the effects of the present invention.
In addition, as above-mentioned, the translucent stretched film of this invention has the texture of paper even if it does not contain inorganic substances, such as a calcium carbonate. Therefore, in order not to disturb the above characteristics of the present invention, the inorganic substance in the base material 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 of the total mass of the base material layer. Or it is preferable to set it as 0 mass% (it does not contain an 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, dibutylhydroxytoluene, 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. Among these, at least one selected from phenolic antioxidants or a combination thereof, or a combination of phenolic and phosphite, and phenolic and lactone, phenolic, phosphite and lactone Is preferable from the viewpoint of imparting chemical stability of the film.

  Examples of the lubricant include organic lubricants and inorganic lubricants. Examples of organic lubricants include aliphatic amides such as stearamide and erucamide, lauric acid diethanolamide, alkyldiethanolamine, aliphatic monoglycerides, aliphatic diglycerides, and silicone cross-linked polymers. Examples of inorganic lubricants include silica and alumina. An organic lubricant is preferred in that the printing plate is less soiled for printing purposes.

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

Examples of the antistatic agent include alkylmethyl dibetaine, alkylamine diethanol and / or alkylamine ethanol ester and / or alkylamine diethanol diester. Of these, two or more kinds of antistatic agents may be used in combination, and an aliphatic alcohol may be used in combination.
Among these, it is preferable to use stearyl diethanolamine monostearate and stearyl diethanolamine in combination because of excellent antistatic performance and improved printability.
As a typical example of a commercially available antistatic agent, there is an electro stripper 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 min 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 is measured using a melt indexer manufactured by Toyo Seiki Seisakusho Co., Ltd., in accordance with 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 min, preferably 0.02 to 1.5 g / 10 min, more preferably 0.02 to 1 g / min. 10 minutes, more preferably 0.03 to 0.5 g / 10 minutes, and particularly preferably 0.03 to 0.1 g / 10 minutes. When the crystalline resin D has a melt mass flow rate at 190 ° C. and 2.16 kg of less than 0.02 g / 10 minutes, fish eyes are generated and the appearance of the film is deteriorated. On the other hand, if the melt mass flow rate at 190 ° C. and 2.16 kg exceeds 2 g / 10 minutes, roughening becomes insufficient, and as a result, an appropriate matte appearance cannot be obtained. As crystalline resin D, crystalline resin D having a melt mass flow rate at 190 ° C. and 2.16 kg of 0.02 to 0.1 g / 10 min and crystalline resin D of 0.11 to 1.5 g / 10 min Is a preferred embodiment from the viewpoints of printability and pencil writing properties, and the crystalline resin D of 0.03 to 0.1 g / 10 min and the crystalline resin D of 0.11 to 1 g / 10 min It is a more preferable aspect to use together.

  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 crystalline polyethylene resins, crystalline polypropylene resins, crystalline polystyrene resins, and the like, and these can be used alone or in admixture of two or more. Among these, from the viewpoints of printability and pencil writing properties, 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 consists of high density polyethylene and low density polyethylene. At least one selected from the group is more preferable, and two types of high-density polyethylene and low-density polyethylene are more preferable. By using these two types in combination, it is easy to improve 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). In this specification, low density polyethylene includes linear low density polyethylene. The 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 α-olefins having 3 to 20 carbon atoms. Includes 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 shows a sharp molecular weight distribution as compared with a conventional catalyst (Ziegler-Natta catalyst) may be used.

  A commercially available resin may be used as the crystalline resin D. Typical commercially available products include, for example, Hi-Zex (registered trademark) 7000F, Primex Corporation, Hi-X (registered trademark) 3300F, Novatec (registered trademark) HF111K, Novatec (registered trademark) HE30, Novatec (registered trademark) (Trademark) LF280 etc. are mentioned.

  In addition to the crystalline resin D, the surface layer may further contain a crystalline thermoplastic resin A ′ (hereinafter also referred to as 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 obtained more suitably. Examples of such a 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) (i) to (iv) above All of the descriptions of the preferred embodiments are the same as (i) to (v) of the crystalline resin A described above 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 resin components. The crystalline resin A ′ used in the surface layer and the crystalline resin A used in the base material layer may be used in combination with the same type of resin or different types of resins. .

Further, the surface layer includes a crystalline thermoplastic resin C ′ (hereinafter referred to as crystalline resin C ′) in addition to crystalline resin D (and optionally crystalline resin A ′, amorphous thermoplastic resin B described later). Can also be contained as a resin component. When the crystalline resin C ′ is contained as the resin component of the surface layer, desired non-uniformity of whiteness such as desired total light transmittance and paper texture can be obtained more suitably. Examples of the crystalline resin C ′ include the same resins as the crystalline resin C that can be used for the base material layer. Specific (i) type of resin component of crystalline resin C ′, (ii) melt mass flow rate, (iii) melting point, (iv) glass transition temperature, (v) preferred above (i) to (iv) All descriptions such as the aspect are the same as the above (i) to (v) of the crystalline resin C described above in the description of the base material layer. Therefore, the description including the above (i) to (v) of the crystalline resin C ′ is omitted here. Each of the crystalline resins C ′ may be used alone, or two or more resin components may be used in combination.
The crystalline resin C ′ used in the surface layer and the crystalline resin C used in the base material layer may be used in combination with the same type of resin or different types of resins. .

  In addition to the crystalline resin D (and optionally the crystalline resin A ′, the crystalline resin C ′ described above), the surface layer includes an amorphous thermoplastic resin B (hereinafter also referred to as an amorphous resin B). Can also be contained as a resin component. When the amorphous resin B is contained as a resin component of the surface layer, desired white light non-uniformity such as desired total light transmittance and paper texture can be obtained more suitably. The amorphous resin B is a resin in which the melting point is not confirmed in the above-mentioned DSC measurement, but the 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 more 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, still more preferably 135 ° C. or higher, and still more preferably 140 ° C. or higher. Preferably it is 144 degreeC or more, Most preferably, it is 148 degreeC or more. In the present invention, the glass transition temperature of the amorphous resin B was measured using an input compensation DSC and Diamond DSC manufactured by Perkin Elmer.

  The amorphous resin B preferably has a melt mass flow rate at 260 ° C. and 2.16 kg of 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 excellent in mixing and dispersibility with the crystalline resin A, and it is easy to obtain translucency within a desired total light transmittance range. In the present invention, the melt mass flow rate of the amorphous resin B was measured using a melt indexer manufactured by Toyo Seiki Seisakusho Co., Ltd. according to JIS K 7210: 1999.

  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. Linear, branched or cyclic polyolefin resin, polyamide resin, polyimide resin, polyether resin, polyesteramide resin, polyetherester resin, acrylic resin, polyurethane resin, polycarbonate resin Polyvinyl chloride resin, polyacrylonitrile, polyphenylene sulfide, polystyrene, fluorine resin and the like can be exemplified. Among these, there are various types of monomers to be copolymerized, and it is easy to adjust the material properties depending on the monomer types. Therefore, amorphous cyclic olefin copolymer, copolymerized polyester resin, polyolefin resin, polyamide A resin, an acrylic resin, or a mixture thereof is preferable. In particular, when an amorphous cyclic olefin copolymer is used, it is preferable because an appropriate void portion is easily formed and a suitable total light transmittance is obtained. The reason is not necessarily clear, but the amorphous cyclic olefin copolymer has a small density ratio between the melt density and the solid density, and the resin shrinkage in the process from melt extrusion to cooling is crystalline resin D (crystalline resin). When A ′ is contained, it is greatly different from the crystalline resin D and the crystalline resin A ′), so that an appropriate void is easily formed, and as a result, it is presumed that a suitable total light transmittance is easily obtained.

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

Cyclic olefins 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 - DOO Cyclo ^[4.4.0.1 2.5] -3- decene, tetracyclo [4.4.0.1 ^{2, 5.} 1 ^7,10 ] dodec-3-ene and the like and derivatives thereof.

  The glass transition temperature of the amorphous cyclic olefin copolymer is, for example, increased 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. Can be adjusted within range. Preferably, content of a cyclic olefin component is 70-90 mass%, and content of linear olefin components, such as ethylene, is 30-10 mass%. More preferably, content of a cyclic olefin component is 75-85 mass%, and content of linear olefin components, such as ethylene, is 25-15 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.

Cyclic olefins include bicyclo [2.2.1] hept-2-ene (bicyclo [2.2.1] hept-2-ene and norbornene from the viewpoint of productivity, transparency, and easy increase in Tg. And its derivatives, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (also referred to as tetracyclododecene) and its derivatives are preferred. The linear olefin component is preferably at least one selected from the group consisting of ethylene, propylene and 1-butene, more preferably ethylene, from the viewpoint of reactivity.

  Further, in addition to the cyclic olefin and the linear olefin, other copolymerizable unsaturated monomer components can be copolymerized as necessary within the range not impairing the object of the present invention. Such other copolymerizable unsaturated monomers may act as molecular weight regulators such as 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, etc. It can be mentioned.

  Furthermore, a hydrogenated product of an amorphous cyclic olefin copolymer can also be used as the amorphous resin B. A hydrogenated product in which almost all of the double bonds are saturated by hydrogenation is preferable because it provides improved heat resistance and weatherability. The hydrogenation rate of the hydrogenated product is preferably 90% or more, more preferably 99% or more.

  A commercially available amorphous resin B may be used. Representative commercial products include, for example, TOPAS Advanced Polymers GmbH's TOPAS (registered trademark) 6015S-04, 6017S-04, 6013M-07, etc. Registered trademark) F4520 and the like.

  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 still more preferably 5 to 50% by mass based on the total mass of the resin components in the surface layer. 15-45 mass% is still more preferable, and 35-45 mass% is especially preferable. If 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 matte 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 components in the surface layer. It is 45 to 95% by mass, more preferably 45 to 90% by mass, still more preferably 45 to 80% by mass, and particularly preferably 45 to 65% by mass. If the content of the crystalline resin A ′ in the surface layer is within the above range, it is preferable because the stretchability is excellent and the roughening is sufficient. When the surface layer contains the crystalline resin A ′, the mass ratio of the content of the crystalline resin D and the crystalline resin A ′ is crystalline resin D: crystalline resin A ′ = 1: 99 to 60:40. Is preferable, 5:95 to 50:50 is more preferable, 15:85 to 45:55 is more preferable, 25: 75 = 45: 55 is still more preferable, and 35:65 to 45:55 is particularly preferable. 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 material layer may be the same or different, respectively. It 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 the resin component of the surface layer. Preferably, it is 5 to 30% by mass, more preferably 7 to 28% by mass, and still more preferably 9 to 26% by mass, based on the total mass. If 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 whiteness non-uniformity such as paper texture can be obtained. Furthermore, it is easy to obtain and roughening is improved, and as a result, occurrence of breakage and the like can be suppressed.
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 material layer may be the same. Or they may be 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 resin component, the crystalline resin D, and optionally used crystallinity Resin A ′, Amorphous Resin B and Crystalline Resin C ′ are different from other resins R ′ exhibiting different melting points and glass transition temperatures, adjustment of stretchability, adjustment of low temperature impact resistance, adjustment of surface roughness. For the purpose of adjusting various physical properties such as rigidity, strength, and elongation, it may be contained within a range not impairing the effects of the present invention.

  As other resin R ', what was illustrated as another resin R used for a base material layer can be used.

  When other resin R ′ is used for the surface layer, the content of such other resin R ′ is preferably 35% by mass or less based on the total mass of the resin components contained in the surface layer. It is more preferable that the amount 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 mass%, 1 mass%, or the like.

The surface layer may contain additives such as heat stabilizers, antioxidants, organic and inorganic lubricants, chlorine scavengers, antistatic agents and the like as optional components in addition to the resin component. Good. Such additives can be used in amounts that do not impair the effects of the present invention. As the additive that can be used for the surface layer, the additives exemplified as the additive that can be used for the base material layer can be used.
In addition, as above-mentioned, the translucent stretched film of this invention has the texture of paper even if it does not contain inorganic substances, such as a calcium carbonate. Therefore, in order not to hinder the above-described characteristics of the present invention, the 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% of the total mass of the surface layer. It is preferable to set it as the mass% (it does not contain an inorganic substance) etc.

The density of the translucent 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 still more preferably 0.76 to 0.00. was 90 g / cm ^3, particularly preferably 0.80~0.88g / cm ^3. When the density is within the above range, it is preferable that translucency within a desired total light transmittance range is easily obtained. Moreover, by setting the density to 0.65 g / cm ³ or more, it is easy to improve the breaking strength and the peel strength within the layer, and the film can be suitably used for packaging applications and the like. The density of the translucent 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, for example, a resin for forming a base layer obtained by blending crystalline resin A and crystalline resin C together with other resin R and / or additives as necessary. A composition (hereinafter, also referred to as a resin composition for a base layer) and a crystalline resin D are changed into a crystalline resin A ′, an amorphous resin B, a crystalline resin C ′, and another resin R ′ as necessary. And / or a resin composition for forming a surface layer (hereinafter also referred to as a resin composition for a surface layer) obtained by blending together with additives and the like, and can be produced by biaxial stretching. .

  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 blend method and a melt blend method. For example, when preparing a resin composition for a base material layer, in the dry blend method, pellets and powders of crystalline resin A and crystalline resin C are used, and pellets and powders of other resin R and / or Alternatively, dry blending is performed using a batch type mixing device such as a tumbler or a mixer, or a continuous metering type mixing device together with the additive. Further, for example, when preparing a resin composition for a base layer, in the melt blending method, pellets and powders of the crystalline resin A and the crystalline resin C, and pellets and powders of other resins R as necessary. And / or it is supplied to a kneader together with an additive, and melt-kneaded to obtain a melt blend resin composition. The preparation of the resin composition for the surface layer is the same as in the case of the base material layer resin composition.

  As a kneader used for melt kneading, a known kneader can be used. For example, a uniaxial screw type, a biaxial screw type, or a multi-axial screw type higher than that can be used. Furthermore, in the case of a screw type of two or more axes, any kneading type of the same direction rotation or the different direction rotation 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 of the 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, the size of the fine dispersion of the crystalline resin C in the crystalline resin A is controlled, and in some cases, the amorphous resin B and / or the crystalline resin C in the crystalline resin A ′. It is preferable because the size of the fine dispersion 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 using a generally known granulator to obtain a pellet-shaped melt blend resin composition.

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

  There is no restriction | limiting in the screw type of an extruder, A 1 axis screw type, a 2 axis screw type, or the multi-screw type more than it can be used. When the resin mixing method is dry blending, a biaxial screw type or higher multiaxial screw type 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. An inert gas such as nitrogen may be purged to prevent thermal degradation of the resin during extrusion.

  As a lamination method for obtaining a laminated film, a conventionally known method such as a coextrusion method, a lamination method, a heat sealing method, or the like can be used. Therefore, the laminated film of the present invention may be a multilayer film obtained by co-extrusion of a base layer resin composition and a surface layer resin composition, and stretching and stretching. It may be a laminate with a film of a multilayer unstretched film obtained by bonding together a base layer extruded as a single layer and a non-stretched film of a surface layer (the base layer may be plural, The type of the base material layer may be different or the same), and may be a multilayer film obtained by stretching.

  Co-extrusion methods include die pre-lamination method in which molten resin is brought into contact with the feed block in front of the die, die-in-die lamination method in which the molten resin is brought into contact with the inner path of the multi-manifold die, and discharge from a plurality of concentric lips. For example, a die outer lamination method in which contact is made with each other. The translucent stretched film of the present invention is composed of, for example, a b layer / a layer composed of a surface layer (b layer) and a base material layer (a layer), a b layer / a having two base material layers. 3 layers of layer b / a layer / b layer with two layers / a layer and surface layer formed, and b layer / a layer / c layer with one surface layer as another layer (c layer) 3 layers, 4 layers of b layer / a layer / a layer / c layer with 2 substrate layers, and one of the 2 layers constituting the substrate layer is another substrate layer A four-layer structure of b layer / a layer / a ′ layer / c layer as (a ′ layer) can be employed.

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

  In the extruded base material layer, the crystalline resin C is dispersed in various sizes in the crystalline resin A. As a result, gaps formed around the crystalline resin C in the subsequent stretching step have various sizes, and partial differences occur in the transmittance, resulting in non-uniformity in whiteness such as paper texture. Will be obtained.

  Examples of the laminating method include an extrusion laminating method using a melt extrusion molding equipment used for the T-die method, and directly molding a laminated film by extruding a molten resin film onto another film.

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

  In the present invention, the above laminating 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 used in combination with the same type of resin or different types of resins. Alternatively, the content of the crystalline resin A in each base material layer may be the same or different. The same applies to the crystalline resin C used in each base layer when the base layer is composed of two or more layers. When their types and / or contents are different, for example, a layer having a high content of the crystalline thermoplastic resin C in the base material layer can easily obtain a desired total light transmittance, and a layer having a low content can be stretched. This makes it easy to achieve both quality and productivity.
In addition, when the surface layer includes two or more layers and each surface layer includes the crystalline resin A ′, the crystalline resin A ′ used in each surface layer may be used in combination with the same kind of resin. Alternatively, 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 has 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 C used in each surface layer. The same applies to '.

The extruded resin sheet is formed into a sheet shape by a known method such as an air knife, another roll, or static electricity on at least one metal drum set to a temperature of 25 ° C. or higher and lower than 120 ° C. Molded into a raw sheet.
If the temperature of the metal drum is within the above range, 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 ′ may be controlled. It becomes possible, the deformation | transformation at the time of extending | stretching is suppressed, and it becomes easy to obtain a desired total light transmittance. A more preferable temperature of the metal drum is 30 to 100 ° C, and a more preferable temperature is 40 to 70 ° C.

  As a stretching method for obtaining the translucent stretched film of the present invention, known methods such as a method of stretching between rolls having a difference in peripheral speed, a tenter method, a tubular method, and the like can be used. As the stretching direction, uniaxial stretching, biaxial stretching, biaxial stretching in an oblique direction, and the like can be performed. For biaxial or more stretching, both sequential stretching and simultaneous stretching are applicable. Among these, since it is easy to obtain a film having a uniform total light transmittance, the simultaneous biaxial stretching method by the tenter method, the sequential biaxial stretching method by the tenter method, and the longitudinal (flow, A sequential biaxial stretching method in which (MD) stretching and then transverse (width, TD) stretching by a tenter method is preferred.

Stretching usually has a film temperature (Ts) between the melting point Tm (A) of the crystalline resin A, which is the main resin among the crystalline resins A contained in the base material layer, and the glass transition temperature Tg (A). The temperature is adjusted to Here, the main resin refers to a resin having the largest content among the crystalline resins A contained in the base material layer (for example, corresponding to A1 in Example 1). Here, the film temperature Ts is the temperature of the film at the time when the film starts to be stretched. When the film temperature is different in each stage in multi-stage stretching such as sequential biaxial stretching, the lowest film among them. Let Ts be the temperature.
When Ts is a temperature close to or lower than the glass transition temperature Tg (C) of the crystalline resin C, the crystalline resin C cannot be sufficiently deformed at the time of stretching, and the interface between the crystalline resin A and the crystalline resin C In some cases, a translucent stretchable film satisfying the desired total light transmittance cannot be obtained by forming a large void in the film and making it opaque. Further, when Ts is a temperature close to or higher than Tm (C), the crystalline resin C easily follows the deformation of the crystalline resin A during stretching to become a transparent film, and the total light transmittance tends to increase. In some cases, a translucent stretched film that satisfies the desired total light transmittance may not be obtained.
Therefore, in the present invention, the following relational expression:
Tm (C)> Tm (A)>Ts> Tg (C)> Tg (A)
Is preferable because a translucent stretched film having non-uniformity of whiteness such as desired total light transmittance and paper texture can be obtained.

  Ts is more preferable when it is 10 ° C. or more higher than Tg (C), more preferably when it is 20 ° C. to 120 ° C. higher than Tg (C), and particularly preferable when it is 20 to 70 ° C. higher. In this case, the crystalline resin C at the time of stretching tends to be appropriately deformed and the total light transmittance tends to be high, and a translucent film showing a desired total light transmittance is easily obtained. Further, when Ts is 80 ° C. to 130 ° C. lower than Tm (C), the deformation of the crystalline resin B is moderately suppressed during stretching, so that the total light transmittance tends to be low, and the desired total light transmission is achieved. This is preferable because a translucent film exhibiting the rate is 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 glass transition temperature of the resin used. First, the raw sheet is preferably 100 to 180 ° C, more preferably 120 to 170 ° C. The film temperature (Ts) is maintained and passed between rolls provided with a difference in peripheral speed or by the tenter method, preferably 2 to 10 times, more preferably 2.5 to 8 times, more preferably in the longitudinal direction. Stretch 3-6 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 The film is stretched 11.5 times, more preferably 3 to 11 times, and then subjected to relaxation and heat setting and wound. If the temperature during stretching is increased, the total light transmittance is likely to increase, and if the temperature is decreased, the total light transmittance is likely to be decreased.

  By stretching the film, voids of various sizes are formed around the crystalline resin C dispersed in the crystalline resin A in the base material layer and, optionally, the surface layer. As a result, a partial difference occurs in the transmittance, and non-uniformity of whiteness such as paper texture is obtained. The crystalline resin C 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 film is used for packaging purposes, a heat seal layer can be laminated on one side and / or both sides of the film as necessary. That is, the translucent stretched film of the present invention may have a heat seal layer.
Preferably, the translucent stretched film of the present invention has a heat seal layer on the surface opposite to the surface layer. The surface on the opposite side of the surface layer means, for example, the surface on the back side of the 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 seal layer is a thermoplastic resin having a melting point of 150 ° C. or less, and is an α-olefin monomer having 2 to 10 carbon atoms such as ethylene, propylene, butene, pentene, hexene, octene, and decene. Two or more random copolymers or block copolymers selected from the group are preferred. These copolymers can be used alone or in combination.

  Particularly preferred is a crystalline propylene-α-olefin random copolymer, and examples of the α-olefin include ethylene or an α-olefin having 4 to 20 carbon atoms, such as ethylene, butene-1, hexene-1, and octene. It is preferable to use -1 or the like, and it is particularly preferable to use a copolymer or terpolymer using ethylene or butylene. For example, a propylene-ethylene-butene random copolymer (FL6741G manufactured by Sumitomo Chemical Co., Ltd.) is preferable. You may use together antiblocking agents, such as acrylic resin type microparticles | fine-particles and a silica, in the range which does not impair the effect of this invention in a heat seal layer.

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

The film can be subjected to corona treatment, plasma treatment, flame treatment, etc., as necessary, online or offline. In particular, when this film is used in printing applications, treatments such as corona treatment, plasma treatment, and flame treatment are performed on one and / or both sides of the film for the purpose of improving the wetting and spreading of printing ink and adhesion. It is preferable to carry out. 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 further having smoothness may be provided.

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

  The translucent stretched film of the present invention prevents problems such as contamination of the package due to the removal of inorganic materials, contamination of the printing plate for printing applications, rough cutting surfaces during cutting, and fast cutting blade consumption. Therefore, the ash content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less based on the total mass of the film. The lower limit of ash content is not particularly limited, but it is preferably as small as possible, for example, 0.01% by mass, 0% by mass, and the like. 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 translucent stretched film of the present invention is preferably 10 to 150 [mu] m, more preferably 15 to 100 [mu] m, and still more preferably 20 to 60 [mu] m, although it depends on its use. When the thickness of the film is 10 μm or more, sufficient strength is easily obtained. Moreover, it is excellent in stretchability and productivity as the thickness of a film is 150 micrometers or less.

  When the thickness of the base material layer is comprised of 60 to 95% of the thickness of the translucent stretched film of the present invention and the thickness of the surface layer is comprised of 5 to 40% of the thickness of the film, the desired total light transmittance In addition, non-uniformity in whiteness such as paper texture tends to be obtained, and a matte appearance tends to be obtained.

  The translucent stretched film of the present invention preferably has pencil writing ability. In general, a plastic film cannot be written with a pencil or the like because the film surface is too smooth, but in applications such as transcribing paper, pencil writing is required. When the translucent stretched film of the present invention has a pencil writing property, it can be pencil-written like paper even though it does not contain inorganic particles, and can be used for applications such as transcribing paper. In addition, it is thought that pencil writability is the effect show | played by having roughened the surface moderately.

  The translucent stretched film of the present invention preferably has heat sealability and / or printability. When the translucent 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 for packaging, food packaging, chemical packaging, decoration, labeling, tape substrate, printing substrate, poster paper, thermal paper substrate, recording paper substrate, etc. Can be suitably used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

[Melting mass flow rate of resin (MFR)]
According to JIS K 7210: 1999, it measured using the Toyo Seiki Seisakusho melt indexer. Crystalline resin A and crystalline resin A ′ are measured under the conditions of a measurement temperature of 230 ° C. and a load of 2.16 kg. Amorphous resin B and amorphous resin B ′ are 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, or a measurement temperature of 260 ° C. and a load of 5 kg. The crystalline resin D was measured at a measurement temperature of 190 ° C. and a load of 2.16 kg.

[Melting point of resin, glass transition temperature]
Calculation was performed by the following procedure using an input compensation DSC and Diamond DSC manufactured by Perkin Elmer. 5 mg of each resin was weighed out, packed in an aluminum sample holder, and set in a DSC apparatus. Under a nitrogen flow, the temperature was raised from -40 ° C to 300 ° C at a rate of 20 ° C / minute, held at 300 ° C for 5 minutes, cooled to -40 ° C at 20 ° C / minute, and held at -40 ° C for 5 minutes. Thereafter, the melting point and 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 when multiple melting peaks are shown) is the melting point, and the midpoint glass transition temperature defined in 9.3 (1) of JIS K 7121 The glass transition temperature was taken.

[Film thickness]
It measured based on JISC2330 using Citizen Seimitsu Co., Ltd. paper thickness measuring device MEI-11.

[Total light transmittance of film]
It measured based on JISK7361 using Nippon Denshoku Industries Co., Ltd. haze meter NDH-5000.

[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). In addition, a measurement is the value which measured about the vertical direction and the horizontal direction of the film, and averaged both.

[Non-uniformity of whiteness]
The film was visually observed through the light of a fluorescent lamp, and the degree of unevenness in whiteness was evaluated as follows.
A: There is sufficient unevenness in white, and it can be used as a substitute for paper.
B: There is unevenness in whiteness and can be used as a substitute for paper.
C: Some unevenness in whiteness is observed, but it is insufficient as a substitute for paper.
D: Unevenness of whiteness is not seen and uniform.

[Film ash]
According to JIS-K7250-1 (2006) A method, it measured by the measurement sample amount 200g.

[Heat sealability evaluation method]
In an environment of 23 ° C. and 50% RH, a heat inclined heat sealer HG-100-2 (Toyo Incorporated) with the heat seal surfaces of two samples cut in the MD direction 250 mm and the TD direction 50 mm overlapped with each other. (Seiki Seisakusho Co., Ltd.) was used, and the heat seal treatment was performed under the conditions of a seal temperature of 110 ° C., a seal pressure of 200 KPa, a seal time of 2 seconds, and a width of the heat seal part (corresponding to the MD direction of the film) Next, the TD direction of the sample adjusted to 23 ° C. was cut to 25 mm. Thereafter, using a tensile tester Technograph TGI-1kN (manufactured by Minebea Co., Ltd.), the ends of the two films were sandwiched between the upper and lower chucks, and peeled 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 three measurements was taken as the adhesive strength (N / 25 mm) of the heat seal part.
The adhesive strength was evaluated as follows.
A: 4N or more and less than 6N: The heat seal strength is moderate, and the openability is excellent.
B: 6N or more to less than 8N: The heat seal strength is slightly strong, but the openability is as good as practical.
C: 8N or more: Heat seal strength is strong and difficult to open.
D: Less than 4N: Heat seal strength is weak and impractical.

[Printability evaluation method]
Four-color gravure printing was carried out on a gravure rotary printing press (OSG-550HDX manufactured by Orient Sogyo Co., Ltd.) using Ink Ultima NT805 manufactured by DIC Graphics Corporation. For each of the four colors of CMYK, 100%, 90%, 80%, 70%, 60% of 5 gradations are printed, and the printed part (4 colors x 5 gradations of 20 gradations) is visually observed and evaluated as follows. did. A: No dot omission is seen in any of the folds, and since it is printed clearly, it is very good.
B: No dot dropout is observed in any of the wrinkles, which is good.
C: There are wrinkles in which dot dropout is observed from 1 to 6 mm, but there is no practical problem.
D: The number of wrinkles in which missing dots are observed is 7 to 12 mm, which is not preferable for practical use.
E: There are 13 or more wrinkles with missing dots, which is not practical.

[Pencil writing]
Each film was written with an HB pencil, and the writing state was evaluated according to the following criteria.
A: The writing is deep and clear, and the writing property is very excellent.
B: Although it is inferior to the said evaluation A, it is written clearly clearly, and it is excellent in writing property.
C: Writing is possible at a readable density, and there is no practical problem.
D: Written but thin and practically problematic.
E: Cannot write.

[Wet tension]
The wetting tension on the film surface was measured according to JIS K 6768: 1999 for the corona-treated surface one day after the corona treatment of the stretched film.

In Examples and Comparative Examples, the following resins were used as crystalline resins A and / or A ′.
Prime Polypro (registered trademark) F-300SP (hereinafter also referred to as Resin A1 or A′1): 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
Wintech (registered trademark) WFW5T (hereinafter also referred to as resin A2 or A′2): manufactured by Nippon Polypro Co., 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 resin B.
Topas (registered trademark) 6015S-04 (hereinafter also referred to as Resin B1): manufactured 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

In Examples and Comparative Examples, the following resins were used as 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 min, melting point 247 ° C., glass transition temperature 95 ° C
TPX (registered trademark) DX845 (hereinafter also referred to as resin C2): manufactured by Mitsui Chemicals, polymethylpentene resin, MFR at 260 ° C. and 5 kg = 9 g / 10 min, melting point 232 ° C., glass transition temperature 23 ° C.

In the examples and comparative examples, the following resins were used as the crystalline resin D.
・ HIZEX (registered trademark) 7000F (hereinafter also referred to as resin D1): manufactured by Prime Polymer Co., Ltd., high density polyethylene, MFR at 190 ° C. and 2.16 kg = 0.04 g / 10 min. (Also referred to as Resin D2): manufactured by Nippon Polyethylene Co., Ltd., high density polyethylene, MFR at 190 ° C. and 2.16 kg = 0.05 g / 10 min. Novatec (registered trademark) HE30 (hereinafter also referred to as Resin D3): Nippon Polyethylene Low density polyethylene manufactured by Co., Ltd., MFR at 190 ° C. and 2.16 kg = 0.30 g / 10 min. Novatec (registered trademark) LF280 (hereinafter also referred to as resin D4): manufactured by Nippon Polyethylene Co., Ltd., low density polyethylene, 190 MFR = 0 at 0 ° C. and 2.16 kg 70g / 10 minutes

[Example 1]
The resin A1, resin A2, and resin C1 pellets were each dry blended with a mixer in the proportions shown in Table 1 to prepare a base layer resin composition. Moreover, the pellets of resin A′2 and resin D1 were each dry blended with a mixer at the ratio shown in Table 1 to prepare a resin composition for the surface layer.

  The base layer dry blend resin composition for forming the base layer is a single screw type extruder a, the surface layer dry blend resin composition for forming the surface layer is a single screw type extruder b, Each is injected from a hopper and melted at 280 ° C., and these are extruded as a two-layer laminated resin layer laminated in a two-layer structure of surface layer (b layer) -base layer (a layer) inside a two-layer multimanifold die. It was. The mass ratio of the amount of extruded resin of 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 base material layer side of the extruded resin sheet while pressing it with air pressure on a cooling drum controlled at 45 ° C. using an air knife. In this way, 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 carried out by a sequential biaxial stretching method in which the film was stretched in the longitudinal direction and then stretched in the transverse direction. The film temperature (Ts) was preheated to 138 ° C. in an oven at a set temperature of 158 ° C., and was first stretched up to 4 times in the machine direction at a stretching speed of 6 times / second. Next, the film temperature (Ts) was preheated to 141 ° C. in the same oven and stretched up to 10 times in the transverse direction at a stretching speed of 1 times / second. 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, then discharged from the oven, cooled to room temperature, and stretched to a thickness of 30 μm. A film was obtained. The surface layer side of the obtained stretched film was subjected to corona treatment. The strength of the corona treatment was adjusted so that the wetting 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]
With respect to the surface layer, the same as Example 1 except that 80% by mass of resin A′2 and 20% by mass of resin D1 were used instead of the proportion of the resin component constituting the surface layer described in Example 1 above. Thus, a stretched film of Example 2 was obtained.

Example 3
Regarding the surface layer, it was the same as Example 1 except that 70% by mass of resin A′2 and 30% by mass of resin D1 were used instead of the proportion of the resin component constituting the surface layer described in Example 1 above. Thus, a stretched film of Example 3 was obtained.

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

Example 5
Regarding the surface layer, instead of the resin component constituting the surface layer described in Example 1 and the ratio thereof, the resin A′2 is 60% by mass, the resin D1 is 20% by mass, and the resin D3 is 20% by mass. A stretched film of Example 5 was obtained in the same manner as Example 1 except that it was.

Example 6
Regarding the surface layer, the resin component constituting the surface layer described in Example 1 and the ratio thereof were replaced by 50% by mass of resin A′2, 20% by mass of resin D1, 20% by mass of resin D3, and A stretched film of Example 6 was obtained in the same manner as Example 1 except that 10% by mass of Resin C′1 was used.

Example 7
Regarding the surface layer, instead of the resin component constituting the surface layer described in Example 1 and the ratio thereof, the resin A′2 is 60% by mass, the resin D1 is 20% by mass, and the resin D4 is 20% by mass. A stretched film of Example 7 was obtained in the same manner as Example 1 except that it was.

Example 8
Regarding the base material layer, the resin component constituting the base material layer described in Example 1 and the ratio thereof were replaced by 83% by weight of resin A1, 3.5% by weight of resin A2, and 13.5 of resin C1. Mass% was used. Further, regarding the surface layer, the resin component constituting the surface layer described in Example 1 and the ratio thereof were replaced by 20% by mass of resin D1, 55% by mass of resin A′2, and 25 by resin C′1. Mass% was used. Otherwise (other than the above), the stretched film of Example 8 was obtained in the same manner as in Example 1.

Example 9
Regarding the base material layer, the resin component constituting the base material layer described in Example 1 and the ratio thereof were replaced by 83% by weight of resin A1, 3.5% by weight of resin A2, and 13.5 of resin C1. Mass% was used. Further, regarding the surface layer, the resin component constituting the surface layer described in Example 1 and the ratio thereof were replaced by 24.3% by mass of resin D1, 65.7% by mass of resin A′2, and resin B 10% by mass of “1” was used. Otherwise (other than the above), the stretched film of Example 9 was obtained in the same manner as in Example 1.

Example 10
Regarding the base material layer, the resin component constituting the base material layer described in Example 1 and the ratio thereof were replaced with 86.5% by mass of resin A1, 3.5% by mass of resin A2, and 10% of resin C2. Mass% was used. Further, regarding the surface layer, the resin component constituting the surface layer described in Example 1 and the ratio thereof were replaced by 20% by mass of resin D1, 55% by mass of resin A′2, and 25 by resin C′1. Mass% was used. Otherwise (other than the above), the stretched film of Example 10 was obtained in the same manner as Example 1.

Example 11
Resin A1, resin A2, and resin C1 pellets were each dry blended with a mixer at the ratio shown in Table 1 to prepare a resin composition for a base layer. Moreover, the pellets of resin A′2, resin B′1, resin C′1 and resin D1 were each dry blended with a mixer at the ratio shown in Table 1 to prepare a surface layer resin composition.

  As resin for heat seal layer, 90 parts by mass of propylene-ethylene-butene random copolymer (Sumitomo Chemical Co., Ltd., Sumitomo Nobrene (registered trademark) FL6741G), and propylene-butene copolymer (Mitsui Chemicals, Inc. ) XM-7070) 10 parts by mass, 0.2 parts by mass of amorphous silica (Silicia 730 manufactured by Fuji Silysia Chemical Co., Ltd.) as an antiblocking agent was 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 a single screw type extruder a, the surface layer dry blend resin composition for forming the surface layer is a single screw type extruder b, The resin composition for heat seal layer for forming the heat seal layer was put into a single screw type extruder HS from a hopper and melted at 280 ° C. These were extruded inside a three-layer multi-manifold die as a three-layer laminated resin layer laminated in a three-layer structure of surface layer (b layer) -base material layer (a layer) -heat seal layer (HS). The mass ratio of the extrusion resin amount of the single screw type extruder b, the single screw type extruder a, and the single screw type extruder HS was 2: 7: 1. The heat-seal layer side of the extruded resin sheet was solidified by cooling while being pressed with air pressure on a cooling drum controlled at 45 ° C. using an air knife. As a result, an original sheet was obtained.

  A stretched film of Example 11 was obtained by subjecting the obtained raw sheet to stretching and corona treatment similar to Example 1.

[Comparative Example 1]
Regarding the base material layer, the resin A1 was used alone without dry blending and melt-kneading instead of the resin component constituting the base material layer described in Example 1 and the ratio thereof. In addition, regarding the layer structure of the film, instead of laminating the two-layer structure of surface layer (b layer) -base material layer (a layer) in Example 1, the surface layer (b layer) was not formed. Only the material layer (a layer) was formed. Otherwise (other than the above), the stretched film of Comparative Example 1 was obtained in the same manner as in Example 1.

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

[Comparative Example 3]
Regarding the surface layer, in place of the resin component constituting the surface layer described in Example 1 and the proportion thereof, except that the pellet of the resin A′2 was used alone without carrying out dry blending and melt mixing. In the same manner as in Example 1, a stretched film of Comparative Example 3 was obtained.

[Comparative Example 4]
Regarding the base material layer, instead of the resin component constituting the surface layer described in Example 1 and the ratio thereof, the resin A1 was used alone without dry blending and melt mixing. Moreover, 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 constituting the base material layer described in Example 1 and the ratio thereof. Others (other than those described above) were the same as in Example 1 to obtain a stretched film of Comparative Example 4.

In the following Table 1 and Table 2, the measurement and evaluation result of the stretched film obtained in each Example are shown with the composition of the resin used for each stretched film. In the printability in Table 2,- ^** means that evaluation was not performed because a stretched film having both low glossiness and non-uniformity in whiteness was not obtained.

As shown in Tables 1 and 2, the stretched films of Examples 1 to 11 were translucent stretched films having extremely low gloss and a total light transmittance of 35 to 85%. Further, these films had printability and pencil writing ability even without an inorganic pigment (inorganic particles). Therefore, the stretched translucent film of the present invention is a film having excellent moisture resistance, water resistance, oil resistance and mechanical strength as compared with paper, but with a moderate translucency and low glossiness like paper. It is understood that it can be used as a substitute for paper because it has a good texture and has printability and pencil writing ability.
Moreover, since the stretched film of Example 11 also has heat-sealing property, it can be understood that it can be suitably used for packaging forms that require heat-sealing properties of foods such as bread.

  On the other hand, in Comparative Example 1 in which the crystalline resin A was used as a single component in the base material layer and the surface layer was not formed, only a transparent film having no non-uniformity in whiteness and high glossiness was used. It was not obtained. In Comparative Example 2 in which the surface layer was not formed, a translucent film and a non-uniformity in whiteness were obtained, but a stretched film having high gloss and a matte appearance was not obtained. Furthermore, in Comparative Example 3 using the crystalline resin A as a single component without using the crystalline resin D in the surface layer, although translucency and non-uniformity in whiteness were obtained, the glossiness was high, A stretched film having a matte appearance was not obtained. Moreover, in the comparative example 4 which did not use crystalline resin C in a base material layer, the nonuniformity of whiteness was not acquired. That is, the films obtained in Comparative Examples 1 to 4 did not show the appearance like paper.

Claims (5)

A translucent stretched film including at least a base material layer and a surface layer,
The base material layer has one or more layers containing at least a crystalline thermoplastic resin A having a melting point of 120 to 175 ° C. and a crystalline thermoplastic resin C having a melting point of 200 to 280 ° C. as resin components. And
The surface layer contains at least a crystalline thermoplastic resin D having a melt mass flow rate of 0.02 to 2 g / 10 min at 190 ° C. and 2.16 kg as a resin component,
A translucent stretched film having a total light transmittance of 35 to 85%.   The translucent 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 claim 1 or 2, wherein the crystalline thermoplastic resin D is high-density polyethylene.   The translucent stretched film according to any one of claims 1 to 3, further comprising a heat seal layer on a surface opposite to the surface on which the surface layer is laminated.   The translucent stretched film according to any one of claims 1 to 4, wherein the 60-degree specular gloss on the surface layer side is 1 to 20%.