JP6540325B2 - Translucent stretched film - Google Patents

Description

  The present invention is a plastic film having high moisture resistance, water resistance, oil resistance and mechanical strength as compared to paper, but also has translucency and preferably has excellent printability and heat sealability. The present invention relates to a stretched film which also has a pencil writability and a hand cuttability if desired.

  Conventionally, translucent paper such as transparencies, glassine paper, paraffin paper and sulfuric acid paper is excellent in the visibility of characters and patterns printed on its surface, and the contents can be confirmed. It is used for medicine packaging paper, food packaging paper, cooking sheet, book cover, etc. However, it is difficult to increase the thickness of the paper having such translucency in order to obtain the translucency, and since the thickness is reduced, the mechanical strength is insufficient. In addition, paper dust may be generated during printing, cutting, packaging, etc., which may cause problems such as deterioration of printability and cutting workability, and contamination of packages. In addition, compared with plastic films, they are low in moisture resistance, water resistance and oil resistance, and may not be used for packaging of food and the like containing water and oil. Furthermore, paper generally does not have heat-sealability and can not be used for packaging that requires heat-sealability.

  On the other hand, plastic films are clearly superior in moisture resistance, water resistance and oil resistance to paper compared to paper, and are excellent in mechanical strength even in thin materials, and are therefore used for wrapping paper for food and medicines, and the like. However, because of its high transparency, it can not be said that the visibility of characters or patterns printed on the film surface is good, and because of its high transparency it is difficult to obtain high-class appearance and design, and it is used for packaging of confectionery etc. There is a problem that it is difficult to use paper substitutes such as wasted paper.

In addition, semi-transparent paper can generally be torn by hand without having a cut or the like, and can be hand-opened when used as a packaging bag or the like. There is. In addition, in the case of a transmission paper, etc., a pencil writing property is required because of its use.
However, a general plastic film has no hand cut unless it has a special shape such as a cut and can not be written by a pencil or the like because the film surface is too smooth. Therefore, it may not be possible to use as a paper substitute.

  Patent Document 1 proposes a polypropylene biaxially stretched film having a pearly luster formed from a polypropylene resin composition containing polypropylene and a specific calcium carbonate powder. In addition, Patent Document 2 is characterized in that a film made of a resin composition comprising a crystalline olefin and a cyclic olefin-based resin is stretched three times or more in at least one direction, and the light transmittance is 50% or less. Opaque polyolefin films have been proposed.

  However, since calcium carbonate used in the polypropylene biaxially oriented film described in Patent Document 1 is opaque, a film having a translucent appearance can not be obtained. In addition, contamination of the package due to the falling off of the particles and contamination of the printing plate in printing applications may occur, and it can not be said that cutting workability is also good. Furthermore, it does not have the hand cuttability. In addition, the opaque polyolefin-based film described in Patent Document 2 uses an amorphous cyclic olefin-based resin, and it is difficult to obtain a translucent appearance, and it does not have writability or hand-cutting property by a pencil or the like. It is.

  Under these circumstances, it is a plastic film that has high moisture resistance, water resistance, oil resistance, and mechanical strength compared to paper, but also has translucency, and preferably has excellent printability and heat sealability. It is desirable to have a film that is possessed and, if desired, also has the ability to write in a pencil and the ability to cut by hand.

Japanese Patent Application Laid-Open No. 11-005852 Japanese Patent Application Laid-Open No. 8-73618

  An object of the present invention is to provide a translucent stretched film, preferably a translucent stretched film having excellent printability and heat-sealability, and optionally having pencil writability and hand-breakability.

  As a result of focusing on the melting points and the glass transition temperatures of the two types of crystalline thermoplastic resins constituting the film, the present inventors have found that the two types of crystalline thermoplastic resins have a melting point and a glass transition temperature satisfying a specific relational expression. 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% obtained by combining and using, and the present invention has been completed.

That is, the present invention includes the following.
[1] A crystalline thermoplastic resin A and a crystalline thermoplastic resin B are contained at least as a resin component, and the melting point Tm (A) and the glass transition temperature Tg (A) of the crystalline thermoplastic resin A, the crystalline heat A translucent drawn film having a total light transmittance of 35 to 85%, wherein the melting point Tm (B) and the glass transition temperature Tg (B) of the plastic resin B simultaneously satisfy the following formula.
Tm (B) ≧ Tm (A) + 50 ° C.
Tm (A) Tg Tg (B) + 40 ° C
Tg (B)> Tg (A)
[2] The translucent drawn film according to [1], containing 15 to 45% by mass of the crystalline thermoplastic resin B based on the total mass of the resin component.
[3] The translucent drawn film according to [1] or [2], wherein the ash content is 1% by mass or less based on the total mass of the film.
[4] The translucent stretched film according to any one of [1] to [3], wherein the 60 degree specular gloss is 5 to 35%.
[5] The translucent drawn film according to any one of [1] to [4], wherein Tm (A) is 135 ° C to 175 ° C.
[6] The translucent stretched film according to any one of [1] to [5], wherein Tm (B) is 200 ° C. or higher.
[7] The translucent stretched film according to any one of [1] to [6], which has a Tg (B) of 60 to 130 ° C.
[8] The translucent stretched film according to any one of [1] to [7], wherein the crystalline thermoplastic resin A is a crystalline polyolefin resin.
[9] The translucent stretched film according to any one of [1] to [8], having a heat seal layer on at least one side.
[10] The translucent stretched film according to any one of [1] to [9], wherein the wetting tension on at least one side is 36 to 45 mN / m.
[11] A food packaging bag comprising the translucent stretched film according to any one of [1] to [10].

  The translucent stretched film of the present invention is white and translucent, and is excellent in mechanical strength, moisture resistance, water resistance and oil resistance, so that it is a label, a substrate for tape, a substrate for printing, a poster sheet, It can be suitably used as a thermal paper substrate, a recording paper substrate, and the like. In a preferred embodiment of the present invention, the translucent stretched film of the present invention has excellent printability and heat sealability, and thus can be preferably used for food packaging applications. Further, in a preferred embodiment of the present invention, the translucent stretched film of the present invention can be used for wrapping paper such as food or medicine which needs the hand-cutting property since it can have the hand-cutting property. Furthermore, such a translucent stretched film of the present invention is considered to be an effect containing a fine dispersion of a crystalline thermoplastic resin, but although it does not contain inorganic particles, it can be written with pencil like paper. is there. In addition, since it does not contain inorganic particles, there is no contamination of the package due to the falling off of the inorganic particles, no contamination of the printing plate in printing applications, problems such as rough cutting surface at cutting and rapid consumption of cutting blade occur. Absent.

  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 when used for packaging, it becomes difficult to confirm the contents. If it exceeds 85%, the transparency becomes too high, and the visibility of characters and patterns printed on the film surface is degraded. The translucent stretched film of the present invention preferably has a total light transmittance of 40% to 80%, more preferably 50% to 75%, still more preferably 52 to 70%. If the total light transmittance is in the above range, it is preferable because the stretched film is translucent. In the present invention, the total light transmittance is a value measured in accordance with JIS-K7361, and can be measured using, for example, a haze meter NDH-5000 manufactured by Nippon Denshoku Kogyo Co., Ltd.

  The translucent stretched film of the present invention comprises, as a resin component, a crystalline thermoplastic resin A (hereinafter referred to as crystalline resin A) which is a main resin, and a crystalline thermoplastic resin B (dispersed in the main resin) Hereinafter, it contains at least crystalline resin B). Here, a crystalline thermoplastic resin refers to a temperature of 10 ° C./min from −40 ° C. to 300 ° C. under nitrogen flow using DSC, held for 5 minutes at 300 ° C., 10 ° C./min. It is cooled to 40 ° C., held at −40 ° C. for 5 minutes, and then a thermoplastic resin in which a clear melting peak appears in the DSC curve when the temperature is raised again to 10 ° C./min to 300 ° C.

In the present invention, the melting point Tm (A) and the glass transition temperature Tg (A) of the crystalline resin A, and the melting point Tm (B) and the glass transition temperature Tg (B) of the crystalline resin B are represented by the following (formula 1) , (Equation 2) and (Equation 3) simultaneously.
Tm (B) ≧ Tm (A) + 50 ° C. (Equation 1)
Tm (A) ≧ Tg (B) + 40 ° C. (Equation 2)
Tg (B)> Tg (A) (Equation 3)
When the melting point and the glass transition temperature of the crystalline resins A and B satisfy the above relational expression, a fine dispersion of the crystalline resin B is formed in the crystalline resin A at the time of extrusion molding, and at the time of stretching of the film An appropriate void is formed between the interface of the crystalline resin A which is the main resin and the crystalline resin B dispersed therein, and a translucent stretched film having a desired total light transmittance can be obtained. .

Further, the melting point Tm (A) and the glass transition temperature Tg (A) of the crystalline resin A, and the melting point Tm (B) and the glass transition temperature Tg (B) of the crystalline resin B are the total light transmittances of the obtained film From the point of view of the above, it is preferable to satisfy the following relational expression.
Tm (A) + 120 ° C Tm Tm (B) Tm Tm (A) + 70 ° C
Tg (B) + 90 ° C ≧ Tm (A) Tg Tg (B) + 50 ° C
Tg (A) + 120 ° C ≧ Tg (B) Tg Tg (A) + 60 ° C

  In the present invention, in order to satisfy the above (formula 1), (formula 2) and (formula 3), a crystalline resin B having a melting point of 200 ° C. or more is preferably used. When the melting point Tm (B) of the crystalline resin B is 200 ° C. or more, it becomes easy to control the size of the fine dispersion of the crystalline resin B in the crystalline resin A during the melt extrusion. . In addition, it becomes easy to make the film temperature at the time of film stretching less than Tm (B), and deformation of the crystalline resin B is appropriately suppressed, so that the total light transmittance of the obtained stretched film is lowered. It becomes easy to obtain the stretched film which has translucency. Therefore, the present invention also provides a translucent stretched film having a total light transmittance of 35 to 85%, containing at least a crystalline resin A and a crystalline resin B having a melting point of 200 ° C. or more. The melting point Tm (B) of the crystalline resin B is more preferably 230 ° C. to 280 ° C., still more preferably 240 ° C. to 260 ° C.

  The melting point Tm (A) of the crystalline resin A is preferably 135 ° C. to 175 ° C., more preferably 138 ° C. to 170 ° C., still more preferably 140 ° C. to 166 ° C., particularly preferably 145 ° C. to 164 ° C. Particularly preferably, the temperature is 150 ° C to 163 ° C. If the melting point Tm (A) of the crystalline resin A is within the above range, the productivity of the stretched film and the heat resistance of the resulting stretched film become good, and the fine dispersion of the crystalline resin B in the crystalline resin A It is preferable because it becomes easy to control the size of.

  50 degrees C or less is preferable, and, as for the glass transition temperature Tg (A) of crystalline resin A, -30-30 degreeC is more preferable. Moreover, 60-130 degreeC is preferable, as for the glass transition temperature Tg (B) of crystalline resin B, 70-120 degreeC is more preferable, and 80-110 degreeC is more preferable. If the glass transition temperature Tg (A) of the crystalline resin A and the glass transition temperature Tg (B) of the crystalline resin B are within the above ranges, the crystalline resin A and the crystalline resin B are added when the film is stretched. This is preferable because an appropriate void can be formed between the interfaces of Moreover, since the productivity of a drawn film, the heat resistance of the obtained drawn film, flexibility, low temperature fragility, etc. become favorable, it is preferable.

Examples of the crystalline resin A include crystalline polyolefin resins, crystalline polyester resins, crystalline polyamide resins, crystalline polystyrene resins, and crystalline acetal resins.
Among them, crystalline polyolefin resins are preferable, and crystalline polyolefin resins showing the above-mentioned melting point and glass transition temperature of the crystalline resin A are excellent in stretchability, and the film stretching temperature is the crystalline resin B described later. It is preferable because it becomes appropriate in view of the glass transition temperature and the melting point, and a translucent film exhibiting a desired total light transmittance can be easily obtained. As a crystalline polyolefin resin, homopolymers obtained by polymerizing ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like And copolymers and the like, which may be used alone or as a mixture of two or more.

Among these, crystalline polypropylene resins, in particular, homopolymers of propylene and copolymers of propylene and ethylene are preferable. When a homopolymer of propylene is used as the crystalline resin A, mechanical strength and heat resistance of the film tend to be improved, and when a copolymer of propylene and ethylene is used, the cracking resistance at low temperature may be improved, The surface glossiness tends to be reduced.
Therefore, the crystalline resin A is a homopolymer of propylene alone, a copolymer of propylene and ethylene and / or a mixture with other polymers, or a copolymer of propylene and ethylene It is preferable because the required quality can be obtained by using only and / or other polymers alone, or in the case of a multi-layer construction, by selectively using layers.

  As a homopolymer of propylene, crystalline isotactic polypropylene resin is preferable. In the present invention, the crystalline isotactic polypropylene resin preferably has a mesopentad fraction ([mm mm]) of 92% to 98%, which is a degree of stereoregularity determined by high temperature nuclear magnetic resonance (NMR) measurement. More preferably, it is 93% to 97%. When the mesopentad fraction [mmmm] is 92% or more, the crystallinity of the resin is improved by the high stereoregular component, and high thermal stability and mechanical strength can be obtained. On the other hand, when the mesopentad fraction [mm mm] is 98% or less, the stretchability becomes good.

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

  The pentad fraction representing the degree of stereoregularity is a combination (mm mm or mrrm) of a quint on the same direction alignment “meso (m)” and a different direction alignment “Lasemo (r)” Etc.) is calculated as a percentage from the intensity integral value of each signal derived from For the assignment of each signal derived from mmmm, mrrm or the like, the description of the spectrum such as "T. Hayashi et al., Polymer, vol. 29, p. 138 (1988)" is referred to. The mesopentad fraction ([mm mm]) can be controlled by appropriately adjusting the polymerization conditions such as the polymerization conditions of the polypropylene resin, the type of the catalyst, and the amount of the catalyst.

  As a homopolymer of propylene, a known method, for example, a method of polymerizing propylene in a hydrocarbon solvent using a Ziegler catalyst system comprising titanium and an aluminum compound, a method of polymerizing in liquid propylene (bulk polymerization), and a gas phase What is manufactured by the method to polymerize etc. may be used, and what is marketed may be used. For example, homopolymers of Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., PC412A manufactured by Sun Aroma Co., Ltd., homopolymers of Novatech (registered trademark) series manufactured by Japan Polypropylene Corporation. And Daploy series manufactured by Borealis, 5014L series manufactured by Korea Oil Chemical Industry Co., Ltd., and Sumitomo Nobrene (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd. as homopolymers.

  As a copolymer of propylene and ethylene, both a random copolymer of propylene and ethylene and a block copolymer of propylene and ethylene are preferably used, and 50 wt% or less of ethylene is contained in the copolymer Is more preferred. Typical commercial products include, for example, those of the prime polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., those of the copolymer, and those of the copolymer of the Novatec (TM) series manufactured by Japan Polypropylene Corporation and Wintech. Among the (registered trademark) series and the Sumitomo Nobrene (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd., copolymers and the like can be mentioned.

  The crystalline resin A preferably has a melt flow rate of 0.5 g / 10 min to 8 g / 10 min, more preferably 1 g / 10 min to 6 g / min according to JIS-K7210 and measured at 230 ° C. and 21.18 N. 10 minutes. By setting the melt flow rate in the above range, the flowability of the resin becomes an appropriate range, and the thickness of the stretched film can be produced with high accuracy. In addition, the size of the fine dispersion of the crystalline resin B can be easily controlled in the crystalline resin A, and the desired total light transmittance can be easily obtained.

Examples of the crystalline resin B include crystalline polycarbonate resins, crystalline polyester resins, crystalline polyamide resins, crystalline polystyrene resins, polyphenylene sulfide resins, polymethylpentene resins, and the like. Among these, since the dispersibility in the crystalline resin A is appropriate and easy to control to the desired total light transmittance, and excellent in resistance to water, acid, alkali, salt, etc., it is also used for food packaging applications etc. Crystalline polyester resins, polymethylpentene resins, and crystalline polystyrene resins are preferable because they are easy to use.
It is preferable to use a crystalline polystyrene resin, in particular, because a suitable total light transmittance can be obtained, and the pencil scribing property and the hand-cutting property described later can be imparted. Although the reason is not necessarily clear, although the crystalline polystyrene resin is a resin having the above preferable melting point and glass transition temperature, it is generally crystalline because the specific gravity is not so high as 1.05 or less. It is presumed that the volume occupied in the resin A becomes moderately large, and it is easy to obtain suitable total light transmittance, pencil writability and hand cuttability.

  As the crystalline resin B, these resins may be used alone, or two or more crystalline resins B may be used in combination. By using two or more types of crystalline resin B in combination, the size of the fine dispersion of crystalline resin B in crystalline resin A and the void formed between the interfaces of crystalline resin A and crystalline resin B This is preferable because it tends to cause variation in the size of the paper and to obtain an uneven appearance such as paper texture.

Examples of the crystalline polycarbonate resin, conforming to JIS-K7210, 300 ° C., the melt volume flow rate measured at 11.77N is a 20 to 50 cm ^3/10 min, mixing and dispersion of the crystalline resin A It is easy to obtain translucency in the desired range of total light transmittance, which is preferable.

  When so-called nylon 66, which is synthesized by the polycondensation reaction of hexamethylenediamine and adipic acid, is used as the crystalline polyamide resin, the melting point becomes appropriate and the translucency in the desired total light transmittance range is obtained. It is preferable because it can be obtained.

  As a polyphenylene sulfide resin, those having a specific gravity of 1.4 or less measured in accordance with ASTM-D792 and a tensile modulus of 3.5 GPa or less measured in accordance with ASTM-D638 are desired total light beams Translucency in the range of transmittance is easily obtained, which is preferable.

The polymethylpentene resin has a tensile elastic modulus of 1.8 GPa or more measured at 23 ° C. in accordance with ASTM-D638, and a Vicat softening temperature of 165 ° C. or more, preferably 170 in accordance with ASTM-D1525. It is preferable to easily obtain translucency in the desired total light transmittance range by using a temperature of not less than ° C.
As an example of a typical commercial item of polymethylpentene resin, Mitsui Chemicals Co., Ltd. TPX (trademark) DX845, DX231, DX820, RT18, RT31 etc. are mentioned.

  Among the copolymerization components of the crystalline polyester resin, those having an acid component as a main component of terephthalic acid and a diol component as a main component of ethylene glycol are preferable. 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, more preferably 20 mol% or less of other copolymerization components in the acid component and / or the diol component.

  Examples of the other copolymerizable acid components include isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, 4,4-stilbenedicarboxylic acid, 4,4-biphenyl Dicarboxylic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bisbenzoic acid, bis (p-carboxyphenyl) methane, anthracenedicarboxylic acid, 4,4-diphenyletherdicarboxylic acid, 4,4 -Aromatic dicarboxylic acid components derived from diphenoxy ethane dicarboxylic acid, 5-Na sulfoisophthalic acid, ethylene-bis-p-benzoic acid, etc., adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1,3 -Derived from cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. It includes aliphatic dicarboxylic acid component is. Among them, aromatic dicarboxylic acid components such as isophthalic acid and 2,6-naphthalene dicarboxylic acid are preferable.

  Also, examples of the other copolymerizable diol component 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 Diol component derived from (2-hydroxyethyl ether) and the like. Among them, diethylene glycol and 1,3-propanediol are preferable.

  These crystalline polyester resins may be used alone or in combination of two or more. As a commercial item of crystalline polyester-based resin, Mitsubishi Chemical Industries, Ltd. Novapex (registered trademark) series, Teijin Ltd. TR-8550FF etc. are mentioned, for example.

  It is preferable to use a styrene resin having a syndiotactic structure mainly as the crystalline polystyrene resin. In the present invention, the syndiotactic structure is a syndiotactic structure, that is, a phenyl group or a substituted phenyl group which is a side chain with respect to the main chain formed from carbon-carbon bonds alternately in opposite directions. It refers to one having a three-dimensional structure located.

The tacticity of the crystalline polystyrene resin can be quantified by nuclear magnetic resonance ( ¹³ C-NMR) with isotope carbon. ^The tacticity measured by the ¹³ C-NMR method can be indicated by the abundance ratio of a plurality of consecutive constitutional units, for example, dyad in the case of 2 units, triad in the case of 3 units, and pentad in the case of 5 units. . The polystyrene resin B used in the present invention is usually at least 75%, preferably at least 85%, in a racemic dyad, or at least 60%, preferably at least 75%, in a racemic triad, or at least 30%, preferably 50 It is a styrenic polymer having syndiotacticity or more.

  Types of crystalline polystyrene resins include polystyrene, poly (alkylstyrene), poly (halogenated styrene), poly (halogenated alkylstyrene), poly (alkoxystyrene), poly (vinyl benzoate), hydrogens of these And polymers thereof, and copolymers containing these as main components.

  Examples of poly (alkylstyrenes) include poly (methylstyrene), poly (ethylstyrene), poly (isopropylstyrene), poly (tertiary butylstyrene), poly (phenylstyrene), 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) and the like. Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).

  As a comonomer component of the copolymer containing these structural units, in addition to the monomers of the above-mentioned styrenic polymer, olefin monomers such as ethylene, propylene, butene, hexene and octene, diene monomers such as butadiene and isoprene, cyclic olefin monomers And polar vinyl monomers such as cyclic diene monomers, methyl methacrylate, maleic anhydride, acrylonitrile and the like. Preferred styrenic polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tertiary butylstyrene), poly (p-chlorostyrene), poly (m-chlorostyrene) And poly (p-fluorostyrene), hydrogenated polystyrene and copolymers containing these structural units.

  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 be 3 to 15 mol%. By setting it as the said range, it becomes easy to control the magnitude | size of the fine dispersion of a polystyrene-type resin in crystalline resin A. Therefore, it is possible to lower the total light transmittance into a desired range, and to obtain the manual cut-off property described later. Furthermore, the flexibility of the film is also suitable, and the stretchability is also improved, so that breakage or the like is less likely to occur.

  The molecular weight of the crystalline polystyrene resin used in the present invention is not particularly limited, but preferably the weight average molecular weight is 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. Further, the upper limit of the molecular weight of the polystyrene resin used in the present invention is preferably 3,000,000 or less, more preferably 1,500,000 or less, from the viewpoint of mixing with the crystalline resin A and dispersibility.

  The crystalline polystyrene resin has a melt flow rate of preferably 1 to 40 g / 10 min, more preferably 10 to 35 g / 10 min, measured at 300 ° C. and 11.77 N in accordance with JIS-K7210. By setting the melt flow rate in the above range, it becomes easy to control the size of the fine dispersion of the crystalline resin B in the crystalline resin A. Therefore, desired total light transmittance can be easily obtained.

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

  The crystalline resin A can be used preferably in an amount of 55 to 85% by mass, more preferably 58 to 79% by mass, and still more preferably 62 to 75% by mass, based on the total mass of the resin component. By using the crystalline resin A in the above range, a film excellent in stretchability and mechanical strength can be easily obtained. The crystalline resin B is preferably used in an amount of 15 to 45% by mass, more preferably 21 to 42% by mass, and still more preferably 25 to 38% by mass, based on the total mass of the resin component. By setting the crystalline resin B to 15% by mass or more based on the total mass of the resin component, the total light transmittance is lowered to be in a desired range, and the hand cutability and pencil writability to be described later are improved. be able to. In addition, by setting the crystalline resin B to 45% by mass or less based on the total mass of the resin component, the total light transmittance is made to be within a desired range without lowering too much, and the stretchability is improved, and breakage is caused Occurrence can be suppressed.

  In the translucent stretched film of the present invention, a crystalline resin having a melting point and a glass transition temperature different from that of the crystalline resin A and the crystalline resin B as a resin component in addition to the crystalline resin A and the crystalline resin B Or adjustment of extensibility, adjustment of low-temperature impact resistance, adjustment of surface roughness, adjustment of various physical properties such as rigidity, strength, elongation etc. of amorphous resin (hereinafter, also referred to as “other resin”) It may be contained within the range which does not impair the effect of the present invention for the purpose.

  The other resin is not particularly limited, and conventionally known resins which are considered to be suitable for stretched film applications can be appropriately used in the present invention. Other resins include, for example, polyolefin resins such as polyethylene, polypropylene, poly (1-butene), polyisobutene, poly (1-pentene) and poly (4-methyl-1-pentene), and copolymers thereof Examples of the resin include copolymers of α-olefins such as ethylene-propylene copolymer, propylene-butene copolymer, and ethylene-butene copolymer. In addition, styrene-based resins, vinyl-based resins, polyester-based resins, polyurethane-based resins, nylon-based resins, and copolymers thereof, for example, vinyl monomer-diene monomer copolymers such as styrene-butadiene copolymer and the like And vinyl monomer-diene monomer-vinyl monomer copolymer such as styrene-butadiene-styrene copolymer and the like.

  It is preferable that it is 15 mass% or less on the basis of the total mass of a resin component, and, as for content of such other resin, it is more preferable that it is 10 mass% or less.

  The translucent stretched film of the present invention may, if necessary, contain, as an optional component, an additive such as a heat stabilizer, an antioxidant, an organic and inorganic lubricant, a chlorine capture agent, an antistatic agent, etc. Good.

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

  Examples of lubricants include, as organic lubricants, stearic acid amides, erucic acid amides such as fatty amides, lauric acid diethanolamide, alkyl diethanolamines, aliphatic monoglycerides, aliphatic diglycerides, silicone cross-linked polymers, and inorganic lubricants, silicas. And alumina, etc., but organic lubricants with little contamination of the printing plate in printing applications are preferred.

  Examples of chlorine capture agents 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, and the like. Among these, two or more types of antistatic agents may be used in combination, and an aliphatic alcohol may be used in combination.
Among them, it is preferable to use stearyldiethanolamine monostearate and stearyldiethanolamine in combination because they are excellent in antistatic performance and the printability is improved.
As an example of a typical commercial item of antistatic agent, Kao Corporation electro stripper series etc. are mentioned.

  The translucent stretched film of the present invention can be produced using a conventionally known method. For example, the crystalline resin A and the crystalline resin B may be first blended with other resins and / or additives as required, and then extruded and subjected to biaxial stretching.

  As a method of blending the crystalline resin A and the crystalline resin B, for example, pellets or powders of the crystalline resin A and the crystalline resin B, etc., pellets, powders and / or addition of other resins as necessary There is a method of dry blending using a batch type mixing apparatus such as a tumbler or a mixer, or a continuous metering type mixing apparatus together with an agent. In addition, pellets, powder, etc. of crystalline resin A and crystalline resin B are supplied to a kneader together with pellets, powder and / or additives of other resins as required, and melt-kneaded to melt blend resin The method etc. of obtaining a composition are mentioned.

  In the present invention, the mixing and dispersion of the crystalline resin A and the crystalline resin B are excellent by melting and kneading, and the size of the fine dispersion of the crystalline resin B can be easily controlled in the crystalline resin A. It is preferable because the total light transmittance can be lowered to a desired range. A kneader known in the art may be used as a kneader used for melt kneading, and may be a single screw type, a twin screw type, or a multi-screw type of more than that, and in the case of a screw type having two or more shafts. Either a co-rotation type or a co-rotation type kneading type may be used, but a twin-screw type kneader with co-rotation is preferable because the size of the fine dispersion can be easily controlled.

  The kneading temperature for melt kneading is preferably in the range of Tm (B) to Tm (B) + 50 ° C, and more preferably Tm (B) + 5 ° C to Tm (B) + 30 ° C. By setting the temperature range as described above, the size of the fine dispersion of the crystalline resin B can be controlled in the crystalline resin A, and a desired total light transmittance can be obtained, which is preferable. 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 melt blend resin composition pellets.

  As a stretching method for obtaining the translucent stretched film of the present invention, a known method such as a method of stretching between rolls provided with a peripheral speed difference, 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 are possible, and in the stretching of two or more axes, both sequential stretching and simultaneous stretching can be applied. Among them, from the viewpoint that a film with uniform total light transmittance is easily obtained, the longitudinal direction (flow, etc.) between rolls provided with a simultaneous biaxial stretching method by a tenter method, a sequential biaxial stretching method by a tenter method, and a peripheral speed difference. MD) Sequential biaxial stretching method in which transverse (width, TD) stretching is performed by tenter method after stretching is preferred.

Stretching is usually performed such that the film temperature (Ts) is a temperature between Tm (A) and Tg (A) of the crystalline resin A as the main resin. Here, when Ts is a temperature close to or less than Tg (B), crystalline resin B can not be sufficiently deformed during stretching, and a large gap is formed between the interfaces of crystalline resin A and crystalline resin B. May become opaque, and a translucent stretched film satisfying the desired total light transmittance may not be obtained. In addition, when Ts is a temperature close to or higher than Tm (B), crystalline resin B easily follows deformation of crystalline resin A during stretching to form a transparent film, and the total light transmittance tends to increase easily. In some cases, it may not be possible to obtain a translucent stretched film that satisfies the desired total light transmittance. Therefore, in the present invention, when Ts is lower than Tm (A) and higher than Tg (B), the following relational expression:
Tm (B)> Tm (A)>Ts> Tg (B)> Tg (A)
Is preferable because a translucent stretched film is obtained. Here, the film temperature Ts is the temperature of the film at the time when the film starts to be stretched, but when the film temperature in each stage is different in multi-stage stretching such as sequential biaxial stretching, the lowest film temperature among them Ts.

  Ts is more preferably 10 ° C. higher than Tg (B), and more preferably 20 ° C. to 70 ° C. higher than Tg (B). In this case, the crystalline resin B at the time of stretching is deformed appropriately, the total light transmittance tends to be high, and a translucent film showing a desired total light transmittance is easily obtained. When Ts (T) is lower than Tm (B) by 80 ° C. to 130 ° C., deformation of the crystalline resin B is appropriately suppressed during stretching, which tends to lower the total light transmittance, and the desired total light transmission It is preferable because a translucent film showing the rate is easily obtained.

  Hereinafter, although the method to obtain the translucent stretched film of this invention by a sequential biaxial stretching method is demonstrated, it is not limited to this.

  The dry blend product of crystalline resin A and crystalline resin B obtained as described above and / or melt blend resin composition pellets are supplied to an extruder, heated and melted, and after removing minute foreign substances and the like by a filter etc. Melt-extrusion in sheet form from T-die.

  There is no restriction on the screw type of the extruder, and a single screw type, a twin screw type, or a multi-screw type of more than that may be used, but when the resin mixing method is dry blending, the twin screw type When the multi-screw type screw or more is used, it is excellent in mixing and dispersibility.

  The extrusion temperature is preferably in the range of Tm (B) to Tm (B) + 50 ° C, and more preferably Tm (B) + 5 ° C to Tm (B) + 30 ° C. An inert gas such as nitrogen may be purged to prevent thermal deterioration of the resin during extrusion.

  For example, the melt-extruded resin sheet is formed into a sheet by a known method such as adhesion with at least one or more metal drums set at a temperature of 25 to 120 ° C. by an air knife or another roll, or static electricity or the like. It becomes an original sheet. If the temperature of the metal drum is within the above range, it is possible to control the crystal growth of the crystalline resin B, the deformation at the time of stretching is suppressed, and the desired total light transmittance is easily obtained. The more preferred temperature of the metal drum is 30-70 ° C.

  The translucent stretched film of the present invention may be a stretched film obtained by extruding a dry blend and / or melt blend resin composition from a single layer die, but the purpose is to obtain a desired film thickness etc. Alternatively, it may be a film obtained by laminating a plurality of layers and / or films using a conventionally known lamination method such as co-extrusion method, lamination method, heat sealing method and the like.

  As the co-extrusion method, the pre-die lamination method in which the molten resin is brought into contact in the feed block in front of the mold, the in-die lamination method in which the molten resin is contacted in the route inside the mold Law etc. For example, in the case of the in-die lamination method, a multilayer b such as a three-layer multi-manifold die is used to form a surface layer (skin layer: layer b) and a core layer (layer a). A three-layer structure or the like can be employed.

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

  As a heat sealing method, an external heating method in which a metal body heated to a plurality of bonded films is pressed from the outside of the film and conducted heat melts and bonds the film, and heats the film by high frequency radio waves or ultrasonic waves. Internal heat generation method etc. which generate | occur | produce and join.

  In the present invention, the above-described lamination methods can be used alone or in combination.

  In the case of laminating, the type and the addition amount of the crystalline thermoplastic resin B in each layer may be the same or different. When different, it is easy to obtain desired total light transmittance with a layer containing a large amount of crystalline thermoplastic resin B, improve drawability with a layer with a small amount added, and so on, so that both quality and productivity can be easily achieved. . When two or more layers are laminated, at least one layer contains 15 to 45% by mass of crystalline thermoplastic resin B based on the total mass of the resin component, and at least one layer contains crystalline thermoplastic resin B as a resin It is preferable to contain 0-25 mass% or less based on the total mass of a component.

When the present film is used for packaging and the like, a heat seal layer may be laminated on one side and / or both sides of the present film as required.
Preferably, the translucent stretched film of the present invention has a heat seal layer on at least one side.

The resin used for the heat seal layer is a thermoplastic resin having a melting point of 150 ° C. or less, and is selected from α-olefin monomers having 2 to 10 carbon atoms such as ethylene, propylene, butene, pentene, hexene, octene and decene. Preferred are random copolymers or block copolymers obtained by polymerizing two or more of the above. These copolymers can be used alone or in combination.
Particularly preferred are crystalline propylene-α-olefin random copolymers, and examples of α-olefins include ethylene and α-olefins having 4 to 20 carbon atoms, such as ethylene, butene-1, hexene-1 and octene-. It is preferable to use 1 etc., 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. In the heat seal layer, an antiblocking agent such as acrylic resin fine particles or silica may be used in combination as long as the effects of the present invention are not impaired.

As the sequential biaxial stretching method, it is necessary to adjust the stretching temperature and the stretching ratio according to the melting point and the glass transition temperature of the resin used, but first the original sheet is preferably 100 to 180 ° C, more preferably 120 to 170 ° C The film is maintained at a temperature of between 2 and 10 times, preferably 2.5 to 8 times, more preferably 3 to 6 times in the longitudinal direction by passing it between rolls provided with a peripheral speed difference or by a tenter method. Stretch to. Subsequently, the stretched film is subjected to a tenter method, preferably at a temperature 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 11.5 times More preferably, after stretching by 3 to 11 times, it is relaxed, heat set, and wound up.
The wound film can be cut into a desired product width after being subjected to an aging treatment preferably in an atmosphere of about 20 to 45 ° C. Thus, a stretched film excellent in mechanical strength and rigidity is obtained. When the temperature at the time of stretching is increased, the total light transmittance is likely to be increased, and the hand-cutting property described later is easily improved. When the temperature is decreased, the total light transmittance is easily reduced. Moreover, when the draw ratio is high, there is a tendency that the hand-cutting property in that direction tends to be improved.

The film may be subjected to corona treatment, plasma treatment, flame treatment and the like on-line or off-line as required. In particular, when the present film is used for printing, on one side and / or both sides of the present film, a treatment such as corona treatment, plasma treatment, flame treatment, etc. for the purpose of improving wet ink spreading and adhesion of printing ink. It is preferable to In the present invention, the wetting tension of K6768: 1999 on the film surface is preferably 36 mN / m or more, and more preferably 38 to 45 mN / m.
Alternatively, a printability imparting layer having similar wetting tension and further smoothness may be provided.

  The 60 ° specular glossiness of at least one surface of the translucent stretched film of the present invention is preferably 5% to 35%, more preferably 8% to 30%, and still more preferably 10 to 25%. When the 60-degree specular gloss is 5% to 35%, the texture is paper-like, and the visibility of printed characters and patterns becomes good, which is preferable. In the present invention, the 60 degree specular gloss is a value measured in accordance with JIS-Z8741 (method 3).

  The translucent stretched film of the present invention prevents problems such as contamination of the package due to dropping of the inorganic substance, contamination of the printing plate in printing applications, roughening of the cut surface at cutting, and rapid consumption of the cutting blade, etc. Preferably, the ash content is 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less based on the total mass of the film. The lower limit of the ash content is not particularly limited, but is preferably as small as possible, and is, for example, 0.01% by mass, 0% by mass or the like. In the present invention, the ash content can be measured according to JIS-K 7250-1 (2006) A method.

  The thickness of the translucent stretched film of the present invention is preferably 10 μm to 150 μm, more preferably 15 to 100 μm, and still more preferably 20 to 60 μm, although it depends on the use application. When the thickness of the film is 10 μm or more, sufficient strength is easily obtained. Moreover, it is excellent in a ductility and productivity as the thickness of a film is 150 micrometers or less.

  The translucent stretched film of the present invention preferably has handicapability. In general, plastic films do not have a hand-cutting property unless they have a special shape such as a cut, while semi-transparent paper used for wrapping paper for food and medicine does not have a cut or the like. In any case, it is possible to tear by hand, and when used as a packaging bag etc, it has a hand-cutting property that it can be opened by hand. Therefore, when the translucent stretched film of the present invention has hand-cutting property, it can be used also for wrapping paper for food, medicine and the like which requires hand-cutting property.

  The translucent stretched film of the present invention preferably has pencil writability. In general, a plastic film can not be written by a pencil or the like because the film surface is too smooth, but in applications such as a transparency paper, it is necessary to have a pencil writability. When the translucent stretched film of the present invention has pencil writability, pencil writing can be performed like paper despite the absence of inorganic particles, and it can be used for applications such as transparencies. In addition, pencil writability seems to be an effect containing a fine dispersion of a crystalline thermoplastic resin.

  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 used for packaging, food packaging, medicine packaging, decoration, labels, tapes, printing substrates, poster paper, thermal paper substrates, recording paper substrates, etc. Can be suitably used.

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

[Melt flow rate of resin (MFR)]
According to JIS K-7210 (1999), it measured using the Toyo Seiki Co., Ltd. make melt indexer. As for the measurement conditions, the crystalline resin A was measured at a measurement temperature of 230 ° C. and a load of 21.18 N, and the crystalline resin B was measured at a measurement temperature of 300 ° C. and a load of 11.77 N.

[Melting point of resin, glass transition temperature]
It calculated according to the following procedures using Perkin-Elmer Inc. input compensation type | mold DSC and Diamond DSC. Each resin was weighed to 5 mg, packed into an aluminum sample holder, and set in a DSC. The temperature was raised from -40 ° C to 300 ° C at a rate of 10 ° C / minute under nitrogen flow, held at 300 ° C for 5 minutes, cooled to -40 ° C at 10 ° C / minute, and held at -40 ° C for 5 minutes. Thereafter, the melting point and the glass transition temperature were determined from the DSC curve when the temperature was raised again to 300 ° C. at 10 ° C./min. With the melting peak defined in 9.1 (1) of JIS-K7121 (the maximum melting peak in the case of showing a plurality of melting peaks) as the melting point, the midpoint glass transition temperature defined in 9.3 (1) of JIS-K7121 is It was a glass transition temperature.

[Thickness of film]
It measured based on JIS-C2330 using a Citizen Seimitsu Co., Ltd. paper-paper thickness measuring device MEI-11.

[Total light transmittance of film]
It measured based on JIS-K7361 using Nippon Denshoku Industries Co., Ltd. make haze meter NDH-5000.

[60 degree specular gloss of film]
The specular glossiness at 60 degrees was measured in accordance with JIS-Z8741 (Method 3) using a variable angle gloss meter Model GM-3D manufactured by Murakami Color Research Laboratory. In addition, a measurement is measured about the longitudinal direction and horizontal direction of a film, and it is the value which averaged both.

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

[Pencil writability]
The writing was made on each film with a pencil of HB, and the writing state was evaluated according to the following criteria.
◎: Deep and clearly written, excellent in writing.
○: Can be written at a readable concentration, there is no problem in practical use.
Δ: Writing is possible, but it is thin and there is a problem in practical use.
X: Can not write.

[Hands-off]
The degree of tearing when the film was torn at the fingertip was evaluated according to the following criteria. The evaluation was made for each of the longitudinal direction and the lateral direction of the film.
:: Easy to tear off ○: Some force is required, but it can be torn and there is no problem in practical use.
Δ: It is not practical if the nails are erected and force can not be torn.
X: The film is tenacious and can not be torn.

[Heat sealability evaluation method]
Heat gradient type heat sealer HG-100-2 (Toyo Co., Ltd.) in a state where heat seal surfaces of two samples cut in the MD direction 250 mm and the TD direction 50 mm are overlapped in an environment of 23 ° C. and 50% RH. Heat sealing 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 portion (corresponding to the MD direction of the film) of 1 cm. Then, after the TD direction of the sample temperature-controlled at 23 ° C. is cut to 25 mm, respective ends of the two films are moved up and down using a tensile tester Technograph TGI-1kN (manufactured by Minebea Co., Ltd.) It pinched with the chuck | zipper, 180 degrees peeled at 300 mm / min of tensile speed, and the maximum value of the stress in that case was measured. The average value of the above three measurements was taken as the adhesive strength (N / 25 mm) of the heat seal portion.
The adhesive strength was evaluated as follows.
◎: 4 N or more and less than 6 N: Heat seal strength is appropriate.
○: 6 N or more and less than 8 N: Heat seal strength is slightly strong, but practical.
○: 3 N or more to less than 4 N: Heat seal strength is slightly weak, but practical.
:: 8 N or more: Heat seal strength is strong and difficult to open.
X: Less than 3 N: Heat seal strength is weak and no practical use.

[Print aptitude evaluation method]
Four-color gravure printing was performed using a gravure rotary printing press (OSG-550HDX manufactured by Orient Corporation) using Ink Ultima NT 805 manufactured by DIC Graphics Corporation. 100%, 90%, 80%, 70%, 60%, 5 gradations are printed for each of the 4 colors of CMYK, and the printed area (4 colors × 5 gradations of 20 gradations) is visually observed and evaluated as follows did. ◎: No dropout observed in any of the ridges, good.
○: There are 1 or more and 6 or less wrinkles where missing dots are observed, but there is no problem in practical use.
Δ: There are 7 dots or less and 12 dots or less that show missing dots, which is not preferable for practical use.
X: There are more than 13 tiles that can be seen missing dots, and can not be used in practice.

Example 1
Prime Polypro (registered trademark) F-300SP (made by Prime Polymer Co., Ltd., crystalline polypropylene homopolymer, MFR = 3 g / 10 min, melting point 160 ° C, glass transition temperature-17 ° C) as crystalline resin A and crystalline resin Pellets of Zarek (registered trademark) 142 ZE (made by Idemitsu Kosan Co., Ltd., polystyrene resin copolymer, melting point 247 ° C., glass transition point 95 ° C.) as B are dry-blended and mixed by a mixer at a ratio shown in Table 1 and mixed Raw material pellets were prepared.

  The obtained mixed raw material pellet is charged from a hopper into a device in which a twin-screw extruder (L / D = 25) equipped with a strand die is connected to a Labo Plastomill (Model 4C150) manufactured by Toyo Seiki Seisakusho Co., Ltd. It melt-kneaded at 260 degreeC. The mixed resin was extruded in the form of a strand, cooled with water, and cut into pellets with a strand cutter to obtain melt blend resin composition pellets.

  Melt blend resin composition pellets are charged from a hopper into a single screw type extruder a for forming a core layer and a single screw type extruder b for forming a skin layer, and these are melted, and these are three-layer multi-manifold It laminated | stacked on three-layer structure of bab in die inside, and extruded as a three-layer lamination resin layer. The ratio of the extruded resin amount of the single screw type extruder a to the single screw type extruder b was 2: 1. The extruded resin layer was cooled and solidified while being pressed by a pneumatic blade on a cooling drum controlled to 45 ° C. using an air knife to obtain an original sheet.

  The obtained original 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 of stretching in the longitudinal direction and then stretching in the lateral direction. The film temperature (Ts) was preheated to 135 ° C. in an oven at a set temperature of 150 ° C., and first stretched in the longitudinal direction to 5 times at a stretching rate of 6 times / sec. Next, the film temperature was preheated to 145 ° C. in an oven at a set temperature of 165 ° C., and stretched in the lateral direction to 10 times at a stretching speed of 1 / sec. Next, in the same oven, relax the transverse direction to 9.5 times at a relaxation rate of 0.5 times / sec, then heat set for 10 seconds, drain from the oven and cool to room temperature, and have a thickness of 30 μm. A stretched film was obtained.

[Examples 2 to 4]
A stretched film was obtained in the same manner as in Example 1 except that the mixing ratio of the raw material pellets was changed to the number of parts shown in Table 1.

[Example 5]
The same raw sheet as in Example 1 was stretched by a simultaneous biaxial stretching method in which stretching in the longitudinal direction and stretching in the transverse direction were simultaneously performed. The film temperature (Ts) was preheated to 145 ° C. in an oven at a set temperature of 165 ° C., and stretched to 7.4 times at a stretching speed of 1 / sec in both the longitudinal direction and the transverse direction. Next, in the same oven, it was relaxed to 7 times in both longitudinal and transverse directions, and after heat setting for 10 seconds, it was discharged from the oven and cooled to room temperature to obtain a stretched film.

[Example 6]
Wintech (registered trademark) WFW 5 T (crystalline propylene-ethylene copolymer, MFR = 2.5 g / 10 min, melting point 142 ° C., glass transition temperature -19 ° C.) 65 weight as crystalline resin A Using a pellet of 35 parts by mass of Zarek (registered trademark) 142 ZE (manufactured by Idemitsu Kosan Co., Ltd., polystyrene resin copolymer, melting point 247 ° C., glass transition point 95 ° C.) as the crystalline resin B, A stretched film is prepared in the same manner as in Example 1 except that the film temperature is preheated to 130 ° C. in the oven at the set temperature of 145 ° C. in the longitudinal direction and the film temperature is 135 ° C. in the oven at the set temperature of 150 ° C. in the horizontal direction. I got

[Example 7]
Same as Example 1 except that Novapex (registered trademark) BK 2180 (Crystalline polyester resin, melting point 250 ° C., glass transition temperature 77 ° C., manufactured by Mitsubishi Chemical Co., Ltd.) is used as the crystalline resin B in the number shown in Table 1 To obtain a stretched film.

Example 8
Same as Example 1 except that Novapex (registered trademark) GS900 (a crystalline polyester resin, made of Mitsubishi Chemical Co., Ltd., crystalline polyester resin, melting point 255 ° C., glass transition temperature 82 ° C.) is used as the crystalline resin B in the number shown in Table 1 To obtain a stretched film.

[Example 9]
Prime Polypro (registered trademark) F-300SP (product of Prime Polymer Co., Ltd., crystalline polypropylene homopolymer, MFR = 3 g / 10 min, melting point 160 ° C., glass transition temperature -17 ° C.) 65 parts by mass as crystalline resin A And 35 parts by mass of Zarek (registered trademark) 142 ZE (manufactured by Idemitsu Kosan Co., Ltd., polystyrene resin copolymer, melting point 247 ° C., glass transition point 95 ° C.) as crystalline resin B using a mixer and mixed raw materials (1 Were prepared.
Prime Polypro (registered trademark) F-300SP (product of Prime Polymer Co., Ltd., crystalline polypropylene homopolymer, MFR = 3 g / 10 min, melting point 160 ° C., glass transition temperature -17 ° C.) 79.7 mass as crystalline resin A 15 parts by weight of ZAREK (registered trademark) 142 ZE (made by Idemitsu Kosan Co., Ltd., polystyrene resin copolymer, melting point 247 ° C., glass transition temperature 95 ° C.) as crystalline resin B, TPX (registered trademark) as crystalline resin B DX-845 (manufactured by Mitsui Chemicals, Inc., polymethylpentene resin, melting point 232 ° C., glass transition temperature 23 ° C., tensile modulus 1.9 GPa, Vicat softening temperature 168 ° C.) 5 parts by mass, antistatic agent electro stripper TS -15 B (stearyl diethanolamine monostearate, stearyl diethanolamine Fine aliphatic mixtures of alcohols were prepared mixture was dry-blended raw material (2) at Kao Corporation) 0.3 parts by mass of the mixer.
The obtained mixed raw material (1) is fed from a hopper into an apparatus in which a twin-screw extruder (L / D = 25) equipped with a strand die is connected to a Labo Plastomill (Model 4C150) manufactured by Toyo Seiki Co., Ltd. It melt-kneaded at 260 degreeC of preset temperature. The mixed resin was extruded in the form of a strand, water-cooled, and cut into pellets with a strand cutter to obtain a melt-blended resin composition pellet (1). Subsequently, melt blend resin composition pellets (2) were obtained in the same manner using the mixed raw material (2).
Melt blend resin composition pellets (1) to single screw type extruder for forming b layer, melt blend resin composition pellets (2) for single screw type extruder to form a layer Each was charged from a hopper and melted, and these were laminated in a three-layer configuration of b-a-b inside a three-layer multi-manifold die and extruded as a three-layer laminated resin layer. The ratio of the extruded resin amount of the single screw type extruder a to the single screw type extruder b was 2: 1. The extruded resin layer was cooled and solidified while being pressed by a pneumatic blade on a cooling drum controlled to 45 ° C. using an air knife to obtain an original sheet.
A stretched film was obtained in the same manner as in Example 1 with respect to the obtained raw sheet. Corona treatment was performed on both sides of the obtained stretched film. The strength of the corona treatment was adjusted so that the wetting tension on the treated surface one day after the treatment was 40 mN / m.

[Example 10]
90 parts by mass of a propylene-ethylene-butene random copolymer (FL6741G manufactured by Sumitomo Chemical Co., Ltd.) and 10 parts by mass of a propylene-butene copolymer (Tafmer MX 7070 manufactured by Mitsui Chemical Co., Ltd.) as a heat seal layer resin The mixed raw material (3) was prepared by dry-blending 0.2 parts by mass of amorphous silica (Silysia 730 manufactured by Fuji Silysia Chemical Co., Ltd.) as an agent with a mixer.
Melt blend resin composition pellets similar to Example 9 in a single screw type extruder b for forming a layer b, melt blend resin composition pellets similar to Example 9 a layer a Single-screw type extruder a for forming, mixed raw material (3) into single-screw type extruder HS for forming HS layer from hopper respectively and melted, these are inside of 3-layer multi manifold die In a three-layer configuration of b-a-HS and extruded as a three-layer laminated resin layer. The ratio of the amount of extruded resin of the single screw type extruder b, the single screw type extruder a, and the single screw type extruder HS was 1: 4: 1. The HS layer side of the extruded resin layer was solidified by cooling while being pressed by an air knife on a cooling drum controlled to 45 ° C. using an air knife to obtain an original sheet.
A stretched film was obtained in the same manner as in Example 1 with respect to the obtained raw sheet. The b 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 on the treated surface one day after the treatment was 40 mN / m.

Comparative Example 1
A stretched film was obtained in the same manner as Example 1, except that Prime Polypro (registered trademark) F-300SP was used alone without performing dry blending and melt mixing.

Comparative Example 2
Zarek® 142 ZE was used alone without dry blending and melt mixing. The pellets are charged from a hopper into a single screw type extruder a for forming a core layer and a single screw type extruder b for forming a skin layer, and these are melted, and these are embedded in a three-layer multi-manifold die Were laminated in a three-layer configuration of b-a-b and extruded as a three-layer laminated resin layer. The ratio of the extruded resin amount of the single screw type extruder a to the single screw type extruder b was 2: 1.
The extruded resin layer was solidified by cooling while being pressed by an air knife using a pneumatic knife on a cooling drum controlled to 80 ° C. to obtain an original sheet.
The obtained original sheet was stretched using a batch type biaxial stretching machine KARO manufactured by Bruckner. The stretching method was carried out by a simultaneous biaxial stretching method in which stretching in the longitudinal direction and stretching in the transverse direction were simultaneously performed. The film temperature (Ts) was preheated to 110 ° C. in an oven at a set temperature of 130 ° C., and stretched to 3 times at a stretching speed of 1 / sec in both longitudinal and transverse directions. Next, heat setting was performed in an oven at a set temperature of 200 ° C. for 20 seconds, and then the oven was discharged and cooled to room temperature to obtain a stretched film.

Comparative Example 3
The mixing ratio of raw material pellets is changed to the number of parts shown in Table 1, and the stretching temperature is preheated to 90 ° C. in the oven at a set temperature of 100 ° C. in the longitudinal direction, and the stretching ratio is in the transverse direction A stretched film was obtained in the same manner as in Example 1 except that the ratio was changed to 8 times.

Comparative Example 4
Cyclic olefin resin which does not use the crystalline resin B, and is instead amorphous and does not show a clear melting peak (melting point) in the DSC curve (Apel (registered trademark) APL 6015, Mitsui Glass Co., Ltd., glass transition temperature 145) A stretched film was obtained in the same manner as in Example 1 except that (C) was used.

Comparative Example 5
Preparation of mixed raw materials by dry blending light calcium carbonate powder (Calcex 5, manufactured by Maruo Calcium Co., Ltd., average particle size 0.9 μm) which is inorganic particles instead of using crystalline resin B in parts shown in Table 1 did.
A molten raw material is charged from a hopper into a single-screw extruder a for forming a core layer and a single-screw extruder b for forming a skin layer, and is melted in the same manner as in Example 1. I got a sheet.
A stretched film was prepared in the same manner as in Example 1 except that the film temperature (Ts) was preheated to 110 ° C. in an oven set at 125 ° C. in the longitudinal direction with respect to the obtained raw sheet. Obtained.

  The measurement and evaluation result of the obtained stretched film put on each Example are shown with the composition of resin used for each stretched film.

As shown in Table 1, the stretched films obtained in Examples 1 to 8 were translucent stretched films having a total light transmittance of between 35 and 85% and a low degree of gloss. In addition, these films had a pencil writability without having an inorganic pigment, and also had a good hand cuttability in at least one stretching direction. Therefore, the 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 has a paper-like appearance due to appropriate translucency and low glossiness. In addition, it is understood that it can be used as a substitute for paper because of its pencilability and handicapability.
In addition, the stretched films obtained in Examples 9 to 10 have a total light transmittance of between 35 and 85%, and show a paper-like appearance because they are translucent stretched films having a low glossiness. In addition, it is excellent in printability and can be suitably used as a high-class packaging bag and the like such as Japanese paper.
In addition, the stretched film obtained in Example 10 has heat sealability, and can be suitably used, for example, in a packaging form requiring heat sealability of foods such as bread.

  On the other hand, in Comparative Examples 1 and 2 in which the crystalline resin was used alone, only a highly transparent film having neither pencil writing properties nor manual cutting properties was obtained. In addition, in Comparative Example 3 in which the amount of the crystalline resin B was too small and the film temperature at the time of stretching was low, the transparency was low, and neither pencil writing nor hand tearability was obtained. Furthermore, the film obtained in Comparative Example 4 in which the amorphous cyclic olefin resin not according to the present invention is used as the crystalline resin B is insufficient in transparency, and in Comparative Example 5 in which light calcium carbonate powder is used. Even small amounts of light calcium carbonate powder did not provide transparency.

Claims (10)

A crystalline thermoplastic resin A and a crystalline thermoplastic resin B at least as a resin component, and the melting point Tm (A) and the glass transition temperature Tg (A) of the crystalline thermoplastic resin A, the crystalline thermoplastic resin B melting point Tm (B) and a glass transition temperature Tg (B) is less than the following formula at the same time, the total light transmittance of Ri 35% to 85% der, 60 degree specular gloss is 5 to 35% crystalline Translucent biaxially stretched film containing the thermoplastic resin B in an amount of 45% by mass or less based on the total mass of the resin component .
Tm (B) ≧ Tm (A) + 50 ° C.
Tm (A) Tg Tg (B) + 40 ° C
Tg (B)> Tg (A) The translucent biaxially stretched film according to claim 1, wherein the crystalline thermoplastic resin B is contained in an amount of 15 to 45% by mass based on the total mass of the resin component. The translucent biaxially stretched film according to claim 1 or 2, wherein the ash content is 1% by mass or less based on the total mass of the film. The translucent biaxially stretched film according to any one of claims 1 to 3 , wherein Tm (A) is 135 ° C to 175 ° C. The translucent biaxially stretched film according to any one of claims 1 to 4 , wherein Tm (B) is 200 ° C or more. The translucent biaxially stretched film according to any one of claims 1 to 5 , wherein Tg (B) is 60 to 130 ° C. The translucent biaxially stretched film according to any one of claims 1 to 6 , wherein the crystalline thermoplastic resin A is a crystalline polyolefin resin. The translucent biaxially stretched film according to any one of claims 1 to 7 , which has a heat seal layer on at least one side. The translucent biaxially stretched film according to any one of claims 1 to 8 , wherein the wetting tension of at least one surface is 36 to 45 mN / m. It is used for applications such as packaging, food packaging, medicine packaging, decoration, labeling, tape substrates, printing substrates, poster paper, thermal paper substrates, or recording paper substrates. The translucent biaxially stretched film according to any one of to 9.