JP5118486B2 - Polyvinylidene chloride resin compound, biaxially stretched film, and method for producing the biaxially stretched film - Google Patents

Description

  The present invention relates to a polyvinylidene chloride resin compound, a biaxially stretched film formed from the polyvinylidene chloride resin compound, and a method for producing the biaxially stretched film. The biaxially stretched film of the present invention is suitable as a packaging material for processed foods such as fish sausages and processed meat products.

  Polyvinylidene chloride resin (hereinafter abbreviated as “PVDC resin”) is generally a copolymer of vinylidene chloride and other monomers copolymerizable with the vinylidene chloride. A homopolymer of vinylidene chloride is close to the melting temperature and the decomposition temperature, and therefore, melt processing such as extrusion molding is difficult. In addition, since the homopolymer of vinylidene chloride is insufficient in compatibility with the plasticizer, improvement of processability by plasticization is insufficient only by adding the plasticizer.

  Therefore, as the PVDC resin, generally, a copolymer having an improved processability by being internally plasticized by copolymerizing vinylidene chloride with another monomer is used. Typical examples of the monomer copolymerized with vinylidene chloride include vinyl chloride and acrylate.

  Extrusion grade PVDC resins formed into films and sheets by extrusion molding are generally powdered PVDC resins having a particle size of 40 to 600 μm (hereinafter referred to as “powder resin”) by suspension polymerization. It is synthesized as. The powder resin alone has poor thermal stability, and decomposes and generates hydrochloric acid gas when melt processed. In addition, even if the powder resin is formed from a copolymer of vinylidene chloride and other monomers, the melting temperature and the decomposition temperature are quite close, so thermal decomposition is sufficiently suppressed. However, it is difficult to perform extrusion molding.

  Therefore, in order to improve the melt processability of the PVDC resin and the properties of the molded product, generally, an additive such as a heat stabilizer, a plasticizer, a lubricant and the like is added to the powder resin made of the PVDC resin to obtain a compound (that is, , A powdery resin composition) and extruding the compound is employed. In the compound, the liquid additive is absorbed in the powder resin, and the solid additive adheres to the surface of the powder resin. The heat stabilizer and / or plasticizer that is liquid at room temperature (10 to 25 ° C.) contains at least a part of the amount used in a monomer composition composed of vinylidene chloride and other monomers in advance. In addition, it can be added by a method of synthesizing a powder resin containing these during suspension polymerization. The remaining heat stabilizer and / or plasticizer is added during compound preparation. By using the PVDC resin compound as a molding material, it is possible to avoid the thermal history associated with pelletization.

  When a PVDC resin compound containing additives such as a heat stabilizer, a plasticizer, and a lubricant is biaxially stretched by an inflation method, a biaxially stretched film excellent in gas barrier properties, heat resistance, and heat shrinkability can be obtained. The biaxially stretched film is widely used as a casing material for processed foods such as fish sausages and processed meat products.

  A method for producing a biaxially stretched film by an inflation method includes a step of supplying a PVDC resin compound to an extruder, melt-kneading, and melt-extruding the molten parison as a tubular melt parison from an annular die disposed at the tip of the extruder; A step of rapidly cooling; a step of reheating the quenching parison to a stretching temperature; and a step of blowing a gas inside the parison to expand it between two pairs of pinch rollers.

  In order to use the biaxially stretched film thus obtained as a casing material for processed foods such as fish sausage and processed meat products, the tubular film obtained by biaxial stretching is folded into a flat shape, and then In many cases, both ends (also referred to as “ear portions”) are cut along the longitudinal direction of the folded film to form a biaxially stretched film (also referred to as “double film”) having a two-layer structure. While the double film is formed into a cylindrical shape by a packaging machine, a casing is manufactured by aligning both ends along the longitudinal direction and heat-sealing (heat sealing), and the casing is filled with processed food. When a predetermined amount of processed food is filled, both ends of the filling portion are gripped and cut to obtain a package (for example, a sausage filled in a casing and gripped at both ends).

  Generally, when a biaxially stretched film is produced using a resin material as a starting material by the inflation method, it is continuously and stably over a long period of time from the viewpoint of control of operating conditions in each process, product quality, product cost, etc. It is desirable to be able to manufacture. However, when a biaxially stretched film is continuously produced by the inflation method using a conventional PVDC resin compound as a starting material, the resulting biaxially stretched film has a width of 0. Foreign matter having a size of 3 mm or more and a length of 0.3 mm or more comes to be observed, and the number of foreign matters increases remarkably when 100 hours have passed.

  Such a brown or black foreign substance can be considered to be a defect derived from a thermal decomposition product of the PVDC resin. In the production process of the biaxially stretched film by the inflation method, first, the PVDC resin compound is supplied from the hopper into the extruder. In the extruder, the PVDC resin compound is extruded to the tip of the extruder by a single screw or a multi-screw having two or more screws, and while being heated, it is heated and melted and kneaded by a heater. At the tip of the extruder, the melt-kneaded material is extruded from an annular die to form a tubular parison. In this extrusion process, the PVDC resin is melt-kneaded at a high temperature, so that it is susceptible to thermal decomposition. The thermal decomposition product of the PVDC resin adheres to and accumulates on the tip of the screw in the extruder and the inner wall surface in the vicinity thereof. When the biaxially stretched film is continuously produced, the pyrolyzate accumulated in the extruder is peeled off from the screw and the inner wall surface of the extruder and mixed into the parison, which causes defects from the pyrolyzate ( Appears as a foreign object).

  The number of defects derived from the thermal decomposition product of the PVDC resin is characterized by a sharp increase at a certain point in the continuous production of the biaxially stretched film. That is, it is presumed that the pyrolyzate accumulated in the extruder is mixed in a large amount in the melt-extruded product (parison) at a certain time. If the number of defects derived from the thermal decomposition product of PVDC resin in the biaxially stretched film increases significantly, the entire production line must be stopped at that point. Production cannot be resumed without disassembling the extruder and cleaning each part. If there are many defects derived from the thermal decomposition product of the PVDC resin in the biaxially stretched film, not only the product value of the package is impaired, but also the gas barrier property is lowered, and the sealing strength at the heat fusion part of the casing is reduced. Or drop.

  In order to improve the melt processability of the PVDC resin compound, it has been proposed to use a compound obtained by adding a lubricant such as wax in addition to a heat stabilizer and a plasticizer to the powder resin of the PVDC resin (for example, JP-A-11-199735, JP-A-2003-26882, JP-A-2003-192861). The lubricant that is solid at room temperature adheres to the surface of the powder resin.

  When a PVDC resin compound having a lubricant attached to the surface of the powder resin is used, accumulation of thermal decomposition products in the extruder can be reduced. However, according to the study by the present inventors, when a PVDC resin compound to which a lubricant such as wax is added is used, continuous operation time is extended to some extent as compared with the case of using a PVDC resin compound to which no lubricant is added. It turns out that although it can be not enough. The addition of a lubricant such as wax cannot sufficiently prevent the PVDC resin thermal decomposition product from accumulating in the extruder.

  The present inventors not only can not extend the continuous operation time so much by increasing the amount of addition of a lubricant such as wax, but also make the biaxially stretched film into a double film (ie, biaxially stretched in a bilayer structure). It was found that delamination tends to occur in the case of film). When delamination occurs in the double film, when both ends of the double film are aligned and heat-sealed together to produce a cylindrical casing, the sealing strength of the heat-sealed part is significantly reduced. Moreover, when delamination occurs in the double film, air or moisture may enter between the layers, which may reduce the gas barrier properties. Further, when delamination occurs in the double film, the product value of the package in which the processed food is filled in the casing formed from the double film is impaired.

  Conventionally, (a) 1.1 parts by weight or less of inorganic stabilizer, (b) 0.45 to 1.05 parts by weight of high density polyethylene, and (c) 0.8 to 1 part by weight based on 100 parts by weight of PVDC resin. 0.0 part by weight of epoxidized vegetable oil, (d) 0.05 to 0.25 part by weight of oxidized polyolefin, and (e) 0.20 to 0.55 part by weight of polyethylene or paraffin wax. A barrier resin composition in powder form has been proposed (corresponding to US Pat. No. 5,002,989; Japanese Patent No. 3179478). In an example of US Pat. No. 5,002,989, the barrier resin composition, an adhesive, and polypropylene are coextruded to obtain a polypropylene layer / adhesive layer / barrier resin composition layer / adhesive layer / polypropylene layer. An experimental example is shown in which a five-layer coextruded sheet is formed and then a container is formed using the sheet.

  As additives for improving the extrudability of polyvinylidene chloride copolymers, alkali metal salts or alkaline earth metal salts of weak acids, and (a) ultra-low density polyethylene, low density polyethylene, medium density polyethylene, and high density An additive comprising a combination of polyethylene selected from the group consisting of polyethylene, (b) plasticizer, and (c) at least one surface lubricant selected from the group consisting of low molecular weight oxidized polyolefin, polyolefin wax, and oil is proposed. (Patent No. 2801323). In this Japanese Patent No. 2801323, “weak acid” is defined as an acid having a measurable dissociation constant, and as a weak acid salt, a salt of an inorganic acid such as magnesium oxide or magnesium hydroxide, Salts of organic acids such as methyltrisodium pyrophosphate are shown.

  In Japanese Patent No. 2801323, as a blending ratio of the additive component, 0.4 to 2% by weight of weak acid based on the total amount of the polymer composition containing the polyvinylidene chloride copolymer and the additive component. An alkali metal salt or alkaline earth metal salt, (a) 0.5-2 wt.% Polyethylene, (b) 0.4-1.2 wt.% Plasticizer, and (c) 0.2-0.3. Weight percent low molecular weight oxidized polyolefins and 0.5 to 0.9 weight percent polyolefin waxes or oils are disclosed.

  In the example of the above-mentioned Japanese Patent No. 2801323, it is described that the polymer composition is melt-extruded as a strand from an extruder into a water bath, and then the strand is cut into pellets. The pellets are put into an extruder and formed into a tape by continuous extrusion. In the molding method specifically disclosed in Japanese Patent No. 2801323, the PVDC resin receives a thermal history at a high temperature twice during pellet molding and tape molding. It is necessary to add ingredients.

  The PVDC resin composition disclosed in the above-mentioned US Pat. Nos. 5,002,989 and 2801323 has a high blending ratio of polyethylene component to PVDC resin and a relatively large blending ratio of wax component. . According to the examination results of the present inventors, a PVDC resin compound in which a polyethylene component and a wax component are used in combination at each blending ratio disclosed in US Pat. No. 5,002,989 and Japanese Patent No. 2801323 is used. When biaxial stretching is performed by the inflation method, the continuous operation time can be extended to some extent, but it is not sufficient, and after 100 to 200 hours, the number of defects derived from the thermal decomposition product of PVDC resin in the biaxially stretched film Was found to increase significantly. Moreover, it was also found that delamination tends to occur when the obtained biaxially stretched film is a double film.

  The problem of the present invention is that even if biaxially stretched film is continuously produced by the inflation method, defects derived from the pyrolyzate of polyvinylidene chloride resin are unlikely to occur, and continuous operation is significantly longer than in the prior art. It is an object of the present invention to provide a polyvinylidene chloride resin compound capable of satisfying the requirements.

  In addition, the problem of the present invention is that, when used as a raw material for producing a biaxially stretched film by an inflation method, in addition to being capable of continuous production over a long period of time, a biaxial biaxial structure in which delamination hardly occurs The object is to provide a polyvinylidene chloride resin compound capable of producing a stretched film (double film).

  Another object of the present invention is to provide a biaxially stretched film formed from the polyvinylidene chloride resin compound as described above.

  Another object of the present invention is to provide a method for producing a biaxially stretched film by the inflation method using the polyvinylidene chloride resin compound as described above.

  As a result of intensive studies to solve the above problems, the present inventors have selected from a group consisting of polyethylene wax and oxidized polyethylene wax (also referred to as oxidized polyethylene wax) as the powder resin made of vinylidene chloride copolymer. At least one synthetic wax powder and at least one polyethylene resin powder selected from the group consisting of high-density polyethylene and low-density polyethylene are added in combination at a limited small blending ratio, and these are added. The inventors have conceived a PVDC resin compound adhered to the surface of the powder resin.

  When a biaxially stretched film is continuously produced by the inflation method using the PVDC resin compound of the present invention as a starting material, a biaxially stretched film with an extremely small number of defects derived from the thermal decomposition product of the PVDC resin even in a continuous operation of 250 hours or more. Can be manufactured. In addition to the additive component, the continuous operation time can be further extended by using calcium stearate and / or an antioxidant together in a small proportion as an external additive.

  In the PVDC resin compound of the present invention, since the addition ratios of the synthetic wax and the polyethylene resin are both extremely small, delamination is suppressed when the biaxially stretched film obtained from the compound is a double film. Since the biaxially stretched film obtained using the PVDC resin compound of the present invention has a very small addition ratio of wax and polyethylene resin, the functions inherent to the PVDC resin such as gas barrier properties are highly maintained. The present invention has been completed based on these findings.

Thus, according to the present invention, a powder comprising a copolymer of 60 to 98% by weight of vinylidene chloride and 2 to 40% by weight of another monomer copolymerizable with the vinylidene chloride and having a particle size of 40 to 600 μm. On the surface of the body-like polyvinylidene chloride resin, with respect to 100 parts by weight of the polyvinylidene chloride resin,
Powder 0.01 to 0.20 parts by weight of at least one synthetic wax selected from the group consisting of polyethylene wax and acid capo triethylene wax, and at least one polyethylene selected from the group consisting of high density polyethylene and low density polyethylene A polyvinylidene chloride resin compound to which 0.01 to 0.20 parts by weight of resin powder is adhered ,
(I) The reduced viscosity of the polyvinylidene chloride resin is 0.035 to 0.070 liter / gram,
(Ii) The polyethylene wax has a melt viscosity of 10 to 1000 mPa · s measured at 140 ° C. using a B-type viscometer, a density measured according to JIS K6760 of 0.85 to 0.97 g / cm ³ , and , Having a characteristic that the melting point measured by a differential scanning calorimeter is 80 to 130 ° C.,
(Iii) The oxidized polyethylene wax is obtained by modifying the polyethylene wax by oxidation, and has an acid value measured according to JIS K5902 of 1 to 30 KOHmg / g,
(Iv) The high density polyethylene has a density measured according to ASTM D792 of 0.942 to 0.970 g / cm ³ , a melt flow rate measured at 190 ° C. according to ASTM D1238 of 0.1 to 20 g / 10 min, and The melting point measured by a differential scanning calorimeter is 120 to 140 ° C., and
(V) the low density polyethylene has a density measured according to ASTM D792 of 0.915 to 0.925 g / cm ³ , a melt flow rate measured at 190 ° C. according to ASTM D1238 of 0.05 to 50 g / 10 min, and The melting point measured by a differential scanning calorimeter is 100 to 115 ° C.
A polyvinylidene chloride resin compound is provided.

  Moreover, according to this invention, the biaxially stretched film formed from the said polyvinylidene chloride resin compound is provided.

Furthermore, according to this invention, it is a manufacturing method of the biaxially stretched film using the said polyvinylidene chloride type-resin compound, Comprising: The following process 1-4:
1) Step 1 of supplying the polyvinylidene chloride resin compound to an extruder and melt-extruding it from an annular die disposed at the tip of the extruder to form a molten parison;
2) Step 2 of quenching the molten parison obtained in Step 1;
3) Step 3 of re-heating the quenched parison to the stretching temperature; and 4) Step 4 of biaxial stretching by blowing a gas into the parison between the two pairs of pinch rollers to expand.
A method for producing a biaxially stretched film is provided.

  FIG. 1 is an explanatory view showing a process for producing a biaxially stretched film by an inflation method.

1. Polyvinylidene chloride resin (PVDC resin)
The PVDC resin used in the present invention is a copolymer of 60 to 98% by weight of vinylidene chloride and 2 to 40% by weight of other monomers copolymerizable with the vinylidene chloride.

  Examples of monomers (comonomer) copolymerizable with vinylidene chloride include vinyl chloride; alkyl acrylate esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and lauryl acrylate (carbon of alkyl group). 1-18); alkyl methacrylates such as methyl methacrylate, butyl methacrylate, and lauryl methacrylate (alkyl group having 1 to 18 carbon atoms); vinyl cyanide such as acrylonitrile; aromatic vinyl such as styrene; vinyl acetate A vinyl ester of an aliphatic carboxylic acid having 1 to 18 carbon atoms; an alkyl vinyl ether having 1 to 18 carbon atoms; a vinyl polymerizable unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid; Alkynes of vinyl polymerizable unsaturated carboxylic acids such as acid and itaconic acid (Including partial esters, C1-18 alkyl group) esters and the like.

  These comonomers can be used alone or in combination of two or more. Among these comonomers, at least one monomer selected from the group consisting of vinyl chloride, methyl acrylate, and lauryl acrylate is preferable.

  When the copolymerization ratio of the comonomer is too small, the internal plasticization of the PVDC resin becomes insufficient and the melt processability is lowered. When the copolymerization ratio of the comonomer is too large, the gas barrier property of the PVDC resin is lowered. The copolymerization ratio of the comonomer is preferably 3 to 35% by weight, more preferably 3 to 25% by weight, and particularly preferably 4 to 20% by weight.

  The reduced viscosity [ηsp / C; unit = liter / gram] of the PVDC resin used in the present invention is preferably from the viewpoints of melt processability, stretch processability, packaging machine suitability, cold resistance, etc. It is 0.035-0.070, More preferably, it is 0.040-0.067, Most preferably, it is 0.045-0.063.

  If the reduced viscosity of the PVDC resin is too low, the stretch processability is lowered, and the mechanical properties of the biaxially stretched film are also lowered. If the reduced viscosity of the PVDC resin is too high, the melt processability is lowered and a tendency to color is exhibited, which is not preferable. Two or more types of PVDC resins having different reduced viscosities can also be used in combination.

  Examples of the PVDC resin include an ethylene-vinyl acetate copolymer, a homopolymer or copolymer of an acrylate ester, a homopolymer or copolymer of a methacrylate ester, and a methyl methacrylate-butadiene-styrene copolymer. Can be blended with other resins. The acrylic ester and methacrylic ester are preferably alkyl esters having 1 to 18 carbon atoms in the alkyl group. The other resin is used at a ratio of 20 parts by weight or less with respect to 100 parts by weight of the PVDC resin.

  The PVDC resin used in the present invention may be synthesized by any polymerization method such as suspension polymerization, emulsion polymerization, solution polymerization, etc., but in order to form a compound as a powder resin, usually 40 to 600 μm, preferably Preferably has a particle size in the range of 50 to 500 μm and is obtained by a suspension polymerization method that does not require a pulverization step.

  The particle size of the powder resin can be measured by a dry sieving method using a standard sieve according to a conventional method.

2. Additive Component Various additives such as a heat stabilizer, a plasticizer, a film surface modifier, and a colorant can be added to the powder resin made of PVDC resin according to a conventional method. Some additives such as a heat stabilizer and a plasticizer can be contained in the monomer composition during the production of the powder resin by the suspension polymerization method. When these additives are added to the powder resin, the liquid additive is absorbed by the powder resin under the temperature conditions at the time of compound production, but the solid additive is in the form of a powder resin. Adhere to the surface. In order to distinguish the additive adhering to the surface of the powder resin made of PVDC resin from the additive contained inside the powder resin, it may be called an external additive.

  Examples of the heat stabilizer include epoxy compounds such as epoxidized vegetable oils, epoxidized animal oils, epoxidized fatty acid esters, and epoxy resin prepolymers; epoxy group-containing resins. These epoxy heat stabilizers can be used alone or in combination of two or more.

  As the epoxidized vegetable oil and epoxidized animal oil, those obtained by modifying a double bond into an oxirane ring by epoxidizing a natural animal or vegetable oil having an unsaturated bond with hydrogen peroxide, peracetic acid or the like can be used. As the epoxidized vegetable oil, epoxidized soybean oil, epoxidized linseed oil and the like are preferable. Epoxidized fatty acid esters include epoxidized products of unsaturated fatty acid esters such as epoxidized octyl stearate. Examples of the epoxy resin prepolymer include bisphenol A glycidyl ether.

  The epoxy group-containing resin is a resin containing at least one epoxy group, and among them, a glycidyl group-containing acrylic resin and a glycidyl group-containing methacrylic resin are preferable. The glycidyl group-containing acrylic resin and / or methacrylic resin is preferably a copolymer containing a vinyl-polymerizable unsaturated organic acid glycidyl ester as a copolymerization component. As the glycidyl group-containing acrylic resin and / or methacrylic resin, glycidyl ester of unsaturated organic acid capable of vinyl polymerization, acrylic acid ester and / or methacrylic acid ester not containing glycidyl group, and copolymerization with these monomers Copolymers with other possible ethylenically unsaturated monomers are preferred.

  Specific examples of the glycidyl group-containing acrylic resin and / or methacrylic resin include glycidyl methacrylate-methyl methacrylate-styrene-butyl acrylate copolymer, glycidyl methacrylate-methyl methacrylate copolymer, glycidyl methacrylate-methyl methacrylate. -Styrene copolymer, glycidyl methacrylate-vinyl chloride copolymer, glycidyl methacrylate-ethyl acrylate copolymer, glycidyl methacrylate-butyl acrylate copolymer, and glycidyl methacrylate-vinylidene chloride copolymer It is done.

  The blending ratio of the heat stabilizer is usually 0.05 to 6 parts by weight, preferably 0.08 to 5 parts by weight, and more preferably 0.1 to 4 parts by weight with respect to 100 parts by weight of the PVDC resin. When the blending ratio of the heat stabilizer is too small, the thermal stability of the PVDC resin compound is deteriorated, making the molding process difficult and causing blackening. If the blending ratio of the heat stabilizer is too large, the gas barrier property and cold resistance of the biaxially stretched film may be lowered, or fish eyes may be caused.

  Among the heat stabilizers, epoxidized vegetable oil is preferred in the field of food packaging materials. A heat stabilizer such as epoxidized vegetable oil is used to prepare a powder resin by containing a part of the amount used in the monomer composition in the polymerization process of the PVDC resin. Can be added to the resin. The total amount of heat stabilizer used may be added during polymerization or may be blended with the powder resin during compound preparation.

  Plasticizers include: phthalic acid derivatives such as dioctyl phthalate; citric acid derivatives such as tributyl acetylcitrate; sebacic acid derivatives such as dibutyl sebacate and dioctyl sebacate; acetylated mono (12-acetoxy) stearyl glyceride, acetylated monoglyceride Acetylated diglycerides, acetylated triglycerides, and acetylated glycerides containing two or three of them; polycondensates of adipic acid and 1,3-butanediol, and polycondensates of adipic acid and 1,4-butanediol Typical examples thereof include polyester plasticizers such as condensates and mixtures of two or more thereof. The compounding ratio of the plasticizer is usually 0.05 to 10 parts by weight, preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the PVDC resin.

  In the polymerization process of PVDC resin, the plasticizer is contained in the PVDC resin powder resin, blended with the PVDC resin powder resin, or a combination thereof, and contained in the PVDC resin compound. Let In order to include the plasticizer in the powder resin produced in the polymerization process of the PVDC resin, the vinylidene chloride and other monomers copolymerizable therewith are copolymerized in the presence of the plasticizer or copolymerized. A plasticizer is added later to produce a PVDC resin powder resin. In the polymerization step, a plasticizer can be contained in the powdered resin of the PVDC resin, and an additional plasticizer can be added as needed during blending. The total amount of plasticizer used may be added during polymerization or may be blended with the powder resin during compound preparation.

  Examples of the film surface modifier include inorganic powders such as silicon dioxide (silica) and calcium carbonate. Silicon dioxide and calcium carbonate act as film surface modifiers such as a matte finishing agent and a film slipperiness imparting agent (also referred to as “film surface lubricant”) in a packaging machine.

  When the film surface modifier is used, it is usually 0.001 to 1 part by weight, preferably 0.01 to 0.80 part by weight, more preferably 0.03 to 100 parts by weight based on 100 parts by weight of the PVDC resin. Used at a blending ratio of 0.50 parts by weight. When at least one inorganic powder selected from the group consisting of silicon dioxide and calcium carbonate is used as a film surface lubricant, it may be used in combination with an organic compound such as stearamide or distearyl thiodipropionate.

  When a scaly inorganic powder such as mica, scaly graphite, scaly metal powder (for example, scaly aluminum powder) is used as a film surface modifier, a biaxially stretched film having a unique color tone and metallic luster is obtained. Can do. When using scale-like inorganic powder, it is used in the ratio of 0.03-4 weight part normally with respect to 100 weight part of PVDC resin, Preferably it is 0.05-3 weight part.

  Examples of the colorant include organic pigments such as azo, phthalocyanine, and quinacridone; inorganic pigments such as titanium oxide, aluminum, mica, and carbon black; extender pigments such as calcium carbonate and magnesium oxide. Among these, red pigments such as Pigment Red are preferable in the field of processed food packaging materials such as fish sausages and processed meat products. The colorants can be used alone or in combination of two or more. The colorant is generally used in a proportion of 0.001 to 3 parts by weight, preferably 0.05 to 2 parts by weight with respect to 100 parts by weight of the PVDC resin. When titanium oxide is used as the colorant, it may be used in a proportion of up to 10 parts by weight with respect to 100 parts by weight of the PVDC resin.

3. The synthetic wax present invention uses at least one synthetic wax selected from the group consisting of polyethylene wax and acid capo triethylene wax. These synthetic waxes are used in the form of powder.

The polyethylene wax used in the present invention is i) a melt viscosity measured at 140 ° C. using a B-type viscometer is usually 10 to 1000 mPa · s, preferably 10 to 600 mPa · s, and ii) measured according to JIS K6760. The density is usually 0.85 to 0.97 g / cm ³ , and iii) the melting point measured by a differential scanning calorimeter is usually 80 to 130 ° C. Polyethylene wax is a low molecular weight substance, and the molecular weight measured by the viscosity method is usually 800 to 5000, preferably about 1000 to 4000. The polyethylene wax includes a high density polyethylene wax (density = 0.95 to 0.97 g / cm ³ ) made of a homopolymer of ethylene, and a low density polyethylene wax made of a copolymer of ethylene and α-olefin. (Density = 0.85-0.95 g / cm ³ ).

  The oxidized polyethylene wax used in the present invention is obtained by modifying the polyethylene wax by oxidation. The oxidized polyethylene wax is oxidized until the acid value measured according to JIS K5902 is usually about 1 to 30 KOHmg / g. The oxidized polyethylene wax has a low acid value type with an acid value of usually 1 to 10 KOH mg / g, typically 1 KOH mg / g, and an acid value of usually 10 to 30 KOH mg / g, often 13 to 25 KOH mg / g. It may be classified as an acid value type. Since the oxidized polyethylene wax is modified by oxidation, the affinity with the inorganic substance is improved. The physical properties such as melt viscosity, density, melting point and molecular weight of oxidized polyethylene wax are equivalent to polyethylene wax.

Proportion of at least one synthetic wax selected from the group consisting of polyethylene wax and acid capo triethylene wax for PVDC resin (powder resin) 100 parts by weight, 0.01 to 0.20 parts by weight, preferably 0.03 to 0.20 parts by weight. If the blending ratio of the synthetic wax is too small, the continuous production time (continuous operation time) of the biaxially stretched film by the inflation method cannot be sufficiently extended even when used in combination with the polyethylene resin. If the blending ratio of the synthetic wax is too large, the continuous production time of the biaxially stretched film by the inflation method cannot be sufficiently extended even when used in combination with the polyethylene resin, and double film delamination occurs. It becomes easy to do. Moreover, when the compounding ratio of the synthetic wax is too large, the gloss and transparency of the film are lowered.

  When the fatty acid calcium and / or antioxidant is externally added to the powdered PVDC resin, the blending ratio of the synthetic wax is preferably set to 0. 100 parts by weight of the PVDC resin (powder resin). Continuous productivity can be further remarkably improved while effectively preventing delamination of the double film by reducing it to 03 to 0.18 parts by weight, more preferably 0.03 to 0.15 parts by weight. .

4). Polyethylene resin In the present invention, at least one polyethylene resin selected from the group consisting of high-density polyethylene and low-density polyethylene is used. These polyethylene resins are used in the form of powder.

The high density polyethylene used in the present invention has i) a density measured according to ASTM D792 of 0.942 to 0.970 g / cm ³ , and ii) a melt flow rate (MFR) measured at 190 ° C. according to ASTM D1238 is usually 0.00. 1 to 20 g / 10 min, preferably 0.3 to 10 g / 10 min, iii) The melting point measured by a differential scanning calorimeter is usually 120 to 140 ° C., preferably 123 to 135 ° C.

The low density polyethylene used in the present invention has i) a density measured according to ASTM D792 of 0.915 to 0.925 g / cm ³ , and ii) a melt flow rate (MFR) measured at 190 ° C. according to ASTM D1238 is usually 0.00. 05 to 50 g / 10 min, preferably 0.1 to 30 g / 10 min, iii) The melting point measured by a differential scanning calorimeter is usually 100 to 115 ° C., preferably 105 to 110 ° C.

  The blending ratio of the polyethylene resin is 0.01 to 0.20 parts by weight, preferably 0.03 to 0.20 parts by weight with respect to 100 parts by weight of the PVDC resin (powder resin). If the blending ratio of the polyethylene resin is too small, the continuous production time (continuous operation time) of the biaxially stretched film by the inflation method cannot be sufficiently extended even when used in combination with polyethylene wax. If the blending ratio of the polyethylene resin is too large, the continuous production time of the biaxially stretched film by the inflation method cannot be sufficiently extended even in combination with polyethylene wax, and delamination of the double film occurs. It becomes easy. Moreover, when the mixture ratio of a polyethylene resin is too large, the glossiness and transparency of a film will fall.

  When the fatty acid calcium and / or the antioxidant is externally added to the powdered PVDC resin, the blending ratio of the polyethylene resin is preferably set to 0.1% with respect to 100 parts by weight of the PVDC resin (powder resin). Continuous productivity can be further remarkably improved while effectively preventing delamination of the double film by reducing it to 03 to 0.18 parts by weight, more preferably 0.03 to 0.15 parts by weight. .

5. Fatty acid calcium and antioxidant The PVDC resin compound of the present invention comprises at least one wax selected from the group consisting of polyethylene wax and oxidized polyethylene wax, and at least one polyethylene selected from the group consisting of high-density polyethylene and low-density polyethylene. In addition to the resin, by adding a small amount of a fatty acid calcium having 14 to 25 carbon atoms and / or an antioxidant, the number of defects derived from the thermal decomposition product of the PVDC resin is further effectively suppressed. , Continuous operation for a long time of 350 hours or more can be made possible.

  As the fatty acid calcium, saturated fatty acid calcium having 14 to 22 carbon atoms is preferable, calcium stearate and calcium palmitate are more preferable, and calcium stearate is particularly preferable. The blending ratio of the fatty acid calcium is preferably 0.001 to 0.20 parts by weight, more preferably 0.003 to 0.10 parts by weight, and particularly preferably 0.005 to 0.005 parts by weight with respect to 100 parts by weight of the PVDC resin. 05 parts by weight. Fatty acid calcium exhibits a sufficient effect even in a small proportion of 0.01 to 0.03 part by weight in many cases. Although fatty acids such as stearic acid are a type of acid, they are generally acids that have substantially no measurable dissociation constant.

  Examples of the antioxidant include triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], dibutylhydroxytoluene (BHT; 2,6-di-tert-butyl- 4-methyl-phenol), various tocopherols of α, β, γ, δ, phenols such as 2,4-dimethyl-6-S-alkylphenol, 2,4-dimethyl-6- (1-methylpentadecyl) phenol Antioxidants; thioether antioxidants such as dilauryl thiodipropionate (DLTDP), distearyl-3,3'-thiodipropionate (DSTDP), thiodipropionic acid; distearyl pentaerythritol diphosphite, etc. Phosphite antioxidants.

  Among these antioxidants, triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], dilauryl thiodipropionate, distearyl-3,3'-thiol. At least one compound selected from the group consisting of dipropionate and dibutylhydroxytoluene is preferred.

  The blending ratio of the antioxidant is preferably 0.001 to 0.20 parts by weight, more preferably 0.003 to 0.10 parts by weight, particularly preferably 0.005 to 0 parts per 100 parts by weight of the PVDC resin. 0.05 parts by weight. Antioxidants can exert a sufficient effect even in a small proportion of 0.01 to 0.03 parts by weight in many cases.

  The fatty acid calcium and the antioxidant can be used alone or in combination. When fatty acid calcium and an antioxidant are used in combination, the total blending ratio is preferably 0.001 to 0.20 parts by weight, more preferably 0.003 to 0.10, relative to 100 parts by weight of the PVDC resin. Part by weight, particularly preferably 0.005 to 0.05 part by weight, and in many cases 0.01 to 0.03 part by weight.

If the blending ratio of the fatty acid calcium and / or the antioxidant is too small, the effect of extending the continuous operation time due to the combined use thereof becomes small. If the blending ratio of the fatty acid calcium and / or the antioxidant is too large, the effect of addition is saturated and it is not economical.

6). Other Additives To the PVDC resin compound of the present invention, surfactants, other stabilizers, ultraviolet absorbers, pH adjusters and the like can be added as necessary.

  Examples of the surfactant include nonionic surfactants such as sorbitan fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, and polyoxyethylene sorbitan fatty acid ester, and an appropriate amount is used as necessary. Fatty acid esters of glycerin (mono, di, tri-ester), fatty acid esters of sorbitan (mono, di, tri-ester) and the like act as a meat release agent for biaxially stretched films for packaging materials. These can be used alone or in combination of two or more.

  Examples of other stabilizers include calcium linoleate, calcium hydroxyphosphate, citric acid, and ethylenediaminetetraacetate, and each can be used in an appropriate amount.

  Examples of the ultraviolet absorber include 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, and an appropriate amount is used as necessary.

  Examples of the pH adjuster include sodium pyrophosphate and disodium dihydrogen pyrophosphate, and are used at a ratio of 0.5 parts by weight or less with respect to 100 parts by weight of the PVDC resin. The pH adjuster is usually used during polymerization of the PVDC resin.

  Examples of the dispersion aid include glycerin and propylene glycols; aliphatic hydrocarbon-based or aromatic hydrocarbon-based oligomers and polymers. Among these, an aliphatic hydrocarbon oligomer having 2 to 8 carbon atoms is preferable. A liquid aliphatic hydrocarbon oligomer having a weight average molecular weight of 300 to 5,000 is particularly preferably used. The dispersion aid has the effect of improving the dispersibility of inorganic additives and organic pigments and preventing scattering, and also has the effect of lowering the melt processing temperature. When a dispersion aid is used, it is used at a ratio of 2 parts by weight or less with respect to 100 parts by weight of the PVDC resin.

7). PVDC resin compound of PVDC resin compound present invention, the powder resin made of PVDC resins, the powder 0.01 to 0.20 weight of at least one synthetic wax selected from the group consisting of polyethylene wax and acid capo triethylene wax And 0.01 to 0.20 parts by weight of a powder of at least one polyethylene resin selected from the group consisting of high-density polyethylene and low-density polyethylene and added to the surface of the powder resin. is there.

  To the powder resin, additives such as an epoxy heat stabilizer, a plasticizer, a film surface modifier, an inorganic additive, and a colorant can be added according to a conventional method. Among these additives, those which are liquid under normal temperature (15 to 25 ° C.) or temperature conditions at the time of compound formation are absorbed by the powder resin. The solid additive adheres to the surface of the powder resin.

  The synthetic wax powder and the polyethylene resin powder are presumed to act as external lubricants. Even when using a PVDC resin compound obtained by adding a synthetic wax to a powder resin alone without using a polyethylene resin, the continuous operation time can be sufficiently extended in the production of a biaxially stretched film by the inflation method. I can't. Even if a PVDC resin compound obtained by adding a polyethylene resin to a powder resin alone is not used in combination with a synthetic wax, the continuous operation time cannot be extended in the production of a biaxially stretched film by the inflation method. .

  To produce a PVDC resin compound, i) a method in which a powder resin and an additive component are mixed at room temperature (15 to 25 ° C.), and ii) a powder resin and an additive component are mixed with the powder resin. A method in which the temperature is maintained under a temperature condition that maintains the form of the body (usually a temperature of up to 80 ° C.), and iii) the powder resin and some of the additive components are mixed with the powder resin. A method of mixing the remaining additive components in the cooling process after raising the temperature and mixing under the temperature condition that maintains the form as described above can be employed. The compound can be prepared by mixing each component using a blender such as a blade blender, a ribbon blender, or a Henschel mixer.

  The solid additive component adheres to the surface of the powder resin at room temperature or under the temperature conditions at the time of compound preparation. The solid additive component such as the synthetic wax or polyethylene resin is used as a powder. When the solid additive component is not a powder, the additive component is pulverized and classified as necessary to obtain a powder.

  The solid additive is preferably a powder having a particle size that passes through a sieve equipped with Tyler mesh # 12 (aperture 1410 μm), and passes through a sieve equipped with Tyler mesh # 20 (aperture 840 μm). A powder having a particle size is more preferable, and a powder having a particle size passing through a sieve equipped with Tyler mesh # 28 (aperture 590 μm) is particularly preferable.

  The lower limit of the average particle diameter of the synthetic wax powder and the polyethylene resin powder is the median diameter (D50) measured by the laser diffraction / scattering method using Shimadzu laser diffraction particle size distribution analyzer SALD-3000 manufactured by Shimadzu Corporation. Typically, it is about 1 μm or 3 μm.

  Since the PVDC resin compound of the present invention is excellent in melt processability, stretch processability, heat resistance and the like, it can be molded by melt extrusion and stretch processing into various molded products. By applying the PVDC resin compound of the present invention to the formation of a biaxially stretched film, a biaxially stretched film with few defects and excellent heat resistance and heat shrinkability can be obtained.

8). Biaxially stretched film and its manufacturing method In this invention, it is preferable to employ | adopt the method of manufacturing a biaxially stretched film continuously by the inflation method using the said PVDC resin compound. The manufacturing method of the biaxially stretched film by the inflation method includes the following steps 1 to 4:
(1) Step 1 in which the polyvinylidene chloride resin compound is supplied to an extruder and melt-extruded from an annular die disposed at the tip of the extruder to form a parison;
(2) Step 2 of rapidly cooling the molten parison obtained in Step 1;
(3) Step 3 of reheating the quenching parison to the stretching temperature; and (4) Step 4 of biaxial stretching by blowing a gas into the parison between the two pairs of pinch rollers to expand.
It is a manufacturing method containing.

In addition to the above steps 1 to 4, the following steps 5 and 6:
(5) Step 5 of folding the cylindrical film obtained by biaxial stretching into a flat shape; and (6) Biaxially stretched film having a two-layer structure by cutting both ends along the longitudinal direction of the folded film. Step 6;
Can be further arranged.

  As shown in FIG. 1, a PVDC resin compound is put into an extruder from a hopper 2 of the extruder 1. In the extruder, by rotating the screw 3, the PVDC resin compound is extruded in the direction of the tip of the extruder and is heated and melted and kneaded by the heater 4. In step 1, the tubular parison 6 is usually melt extruded from the annular die 5 at a resin temperature of 175 to 195 ° C. In step 2, the molten parison 6 is guided to the cooling bath 7 and immersed in the cooling liquid 8 for rapid cooling. The temperature of the cooling liquid is usually kept at a temperature in the range of 3 to 15 ° C, preferably 5 to 13 ° C. As the cooling liquid, it is generally preferable to use water.

  In step 3, the quenching parison 9 is guided to the hot water bath 10 by a group of rollers and immersed in the hot water 11, and the temperature is adjusted to a temperature suitable for stretching. The temperature of the hot water 11 is normally maintained at a temperature in the range of 10 to 40 ° C, preferably 15 to 35 ° C.

  In step 4, the temperature-controlled parison 12 is guided between the two pairs of pinch rollers 13 and 16, and gas is blown into the parison to expand it. The stretching ratio due to expansion is preferably 2 to 5 times in the machine direction (MD) and 2 to 5 times in the transverse direction (TD). When the stretching ratio in the transverse direction (TD) is larger than the stretching ratio in the longitudinal direction (MD), stretching is easy.

  In step 5, the biaxially stretched tubular film 14 is guided to the pinch roller 16 by the guide roller group 15 and folded into a flat shape. It is preferable that the folded biaxially stretched film 17 is held horizontally by two rollers 18 and 19 so that a defect occurrence state can be observed between these rollers. The biaxially stretched film 17 folded into a flat shape is guided to the take-up roller 21 by the roller group 20 and is wound there in a roll shape.

  In Step 6, before the biaxially stretched film 17 folded into a flat shape is guided to the take-up roller 21 or once wound in a roll shape, after being rewound, both ends (ear portions) along the longitudinal direction. Is cut into a biaxially stretched film (double film) having a two-layer structure. A biaxially stretched film thickness is 5-50 micrometers normally as a single layer film, Preferably it is 10-30 micrometers. The double film is twice as thick.

  By using the PVDC resin compound of the present invention as a starting material, it is possible to stably carry out continuous production of a biaxially stretched film by the inflation method over a long period of time. The obtained biaxially stretched film has a small number of defects derived from the thermal decomposition of the PVDC resin, is of high quality, and is excellent in gas barrier properties, heat resistance, and heat shrinkability.

  The biaxially stretched film of the present invention is suitable as a packaging material for processed foods such as fish sausages and processed meat products as a single layer film or a double film. The main usage of the biaxially stretched film is to fold it into a flat shape after biaxial stretching by the inflation method, and to slit the ears at both ends along the longitudinal direction to make a double-layered double film . The double film is formed into a casing by sealing both ends along the longitudinal direction while being cylindrical by a packaging machine. The casing is filled with contents, and both ends are gripped to obtain a package. The biaxially stretched film of the present invention is suitable as a packaging material for processed foods such as fish sausages and processed meat products.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples. The evaluation method used in the present invention is as follows.

(1) Reduced viscosity After extraction with a Soxhlet extractor using a PVDC resin as a methanol solvent, the dried product is used as a sample, and the solvent is cyclohexane, the resin concentration is 4 grams / liter, and the measurement temperature is measured using an Ubbelohde viscometer. The reduced viscosity was determined under the condition of 30 ° C. The reduced viscosity (unit = liter / gram) is one index indicating the degree of polymerization of the PVDC resin, and the larger the value, the higher the degree of polymerization.

(2) Particle size of powder resin The particle size of the powder resin was measured by a dry sieving method (JIS K0069-1) using a standard sieve (JIS Z8801-1).

(3) The number of defects derived from the thermal decomposition product of the PVDC resin The defect derived from the thermal decomposition product of the PVDC resin is a foreign matter generated by causing thermal decomposition during the extrusion process. When the biaxially stretched film is observed visually, this defect is a portion exhibiting reddish brown to black, and shows a distinctly different appearance from the normal portion.

  A biaxially stretched film is continuously produced by an inflation method using a 90 mm diameter extruder with a vacuum hopper (adjusted to a vacuum pressure of about −680 mmHg mercury column) as an extruder, in a bilayer film having a length of 1500 m × width of 1200 mm The number of defects having a length of 0.3 mm or more and a width of 0.3 mm or more observed visually was counted. Continuous operation from the start of production, 3 hours, 10 hours, 20 hours, 50 hours, 100 hours, 150 hours, 200 hours, 250 hours, 300 hours, and 350 hours after the start of production The number of defects was calculated, and production was stopped when the number of defects reached 100 or more.

(4) Evaluation of productivity The biaxially stretched film was continuously produced under the above conditions, and the productivity was evaluated according to the following criteria according to the time when the number of defects derived from the thermal decomposition product of the PVDC resin was 100 or more.
AA: 350 hours continuous operation is possible.
A: Continuous operation for 250 to 300 hours is possible.
B: 100-200 hours continuous operation is possible,
C: 50 hours of continuous operation is possible.

(5) Double film delamination Whether or not the biaxially stretched film having a two-layer structure is cut into a size of 10 cm × 10 cm square to prepare a sample, and both sides of the sample are strongly squeezed by hand to separate the layers. I confirmed.

[Example 1]
(1) Preparation of compound As a PVDC resin, a vinylidene chloride-vinyl chloride copolymer (vinylidene chloride / vinyl chloride = 88/12% by weight, reduced viscosity = 0.58 liter / gram) obtained by suspension polymerization. A powder resin (particle size = 442 μm) was used.

In a blade blender, powder resin 100 parts by weight, heat stabilizer (epoxidized linseed oil) 2.00 parts by weight, plasticizer (dibutyl sebacate) 3.00 parts by weight, film surface modifier [silicon dioxide (SiO 2 ₂ ); made by Mizusawa Chemical Co., Ltd., trade name “Sylphonite M-1”] 0.20 parts by weight, coloring agent (Pigment Red 166, manufactured by Dainichi Seika Co., Ltd.) Product name “Honeywell AC 629A”; melt viscosity = 200 mPa · s, density = 0.930 g / cm ³ , melting point = 95 ° C., acid value = 16 KOHmg / g) 0.10 parts by weight, and high density polyethylene (HDPE; manufactured by Mitsui Chemicals, Inc., trade name "HI-ZEX"; density = 0.952 g / cm ^3, melting point = 131 ℃, MFR = 0.11g / 0min) was added to 0.05 parts by weight, and mixed for 30 minutes at 70 ° C.. The solid additive component had a particle size that passed through the entire sieve equipped with Tyler mesh # 20 (mesh 840 μm).

(2) Manufacture of biaxially stretched film Using a 90 mm diameter extruder equipped with a vacuum hopper (vacuum pressure = adjusted to about −680 mmHg mercury column), the compound prepared above was converted into a tubular parison from an annular die at a resin temperature of 185 ° C. After melt extrusion, the molten parison was quenched with a 7 ° C. cooling bath. Next, the quenching parison is passed through a 20 ° C. hot water bath, and is guided between two pairs of pinch rollers having different rotational speeds. A biaxially stretched film was produced by biaxial stretching at a stretch ratio of 4.2. The biaxially stretched film was folded into a flat state and wound around a winding roller in a roll shape. The results are shown in Table 1.

[Examples 2 to 18]
Biaxially stretched films were continuously produced in the same manner as in Example 1 except that the types and blending ratios of the respective additive components were changed as shown in Tables 1 and 2. A PVDC resin (powder resin), a heat stabilizer, a plasticizer, a film surface modifier, and a colorant had the same formulation as in Example 1.

  However, in Example 11, calcium carbonate was used as the film surface modifier instead of silicon dioxide. The same oxidized polyethylene wax (OPE wax) and high-density polyethylene (HDPE) as those used in Example 1 were used.

The additive components that were not used in Example 1 are as follows.
(1) Polyethylene wax (PE wax): manufactured by Honeywell, trade name “Honeywell A-C617”, melt viscosity = 180 mPa · s, density = 0.910 g / cm ³ , melting point = 97 ° C .;
(2) Low density polyethylene (LDPE): manufactured by Mitsui Chemicals, trade name “Mirason”, density = 0.922 g / cm ³ , melting point = 109 ° C., MFR = 3.3 g / 10 min;
(3) Calcium stearate (CaSt): manufactured by Nitto Kasei Corporation;
(4) Antioxidant 1: Triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], manufactured by Ciba Specialty Chemicals, trade name “Irganox 245”;
(5) Antioxidant 2: Distearyl-3,3′-thiodipropionate, manufactured by API Corporation, trade name “DSTP Yoshitomi”;
(6) Calcium carbonate (CaCO ₃ ): Product name “Mama Carso” manufactured by Nitto Flour Chemical Co., Ltd.

  The solid additive component had a particle size that passed through the entire sieve with Tyler mesh # 28 (aperture 590 μm). The results are shown in Tables 1 and 2.

[Comparative Examples 1-8]
A biaxially stretched film was continuously produced in the same manner as in Example 1 except that the types and blending ratios of each additive component were changed as shown in Table 3. Each additive is the same as that used in Examples 1-18. The results are shown in Table 3.

  As is apparent from the results shown in Tables 1 and 2, the continuous operation time is remarkably increased in the continuous production of the biaxially stretched film by the inflation method by using the specific synthetic wax and the polyethylene resin together in a limited small proportion. You can see that it can be extended.

  According to the results shown in Examples 12 to 18 in Table 2, it can be seen that the continuous operation time can be further extended by further using the fatty acid calcium and / or antioxidant in a small proportion.

  On the other hand, as shown in Table 3, when each of the synthetic wax and the polyethylene resin is used alone, the continuous operation time can be extended as compared with Comparative Example 1 using a compound not containing these. It can be seen that even if it cannot be extended, it is insufficient (Comparative Examples 2 to 4).

  When the synthetic wax is used at a ratio exceeding 0.20 parts by weight with respect to 100 parts by weight of the PVDC resin, delamination occurs in the double film (Comparative Example 4).

  When the blending ratio of the synthetic wax or the blending ratio of the polyethylene resin is increased, delamination is likely to occur in addition to a small effect of extending the continuous operation time (Comparative Examples 5 to 8).

  According to the present invention, even if a biaxially stretched film is continuously produced by an inflation method, a PVDC resin compound that is unlikely to generate defects due to a thermal decomposition product of a PVDC resin and that can be operated continuously for an extremely long time is provided. Is done. In addition, according to the present invention, a biaxially stretched film having a two-layer structure in which delamination hardly occurs can be obtained. Therefore, when the PVDC resin compound of the present invention is used as a starting material, a high-quality biaxially stretched film can be produced with high productivity. Since the biaxially stretched film of the present invention has a small number of defects derived from the thermal decomposition product of the PVDC resin, the biaxially stretched film is excellent in gas barrier properties and has good heat-fusibility during casing production.

  Since the biaxially stretched film of the present invention is heat-shrinkable and excellent in gas barrier properties, it can be used in the technical field of packaging materials for processed foods such as fish sausages and processed meat products.

Claims (15)

A powdery polyvinylidene chloride resin comprising a copolymer of 60 to 98% by weight of vinylidene chloride and 2 to 40% by weight of another monomer copolymerizable with the vinylidene chloride and having a particle size of 40 to 600 μm On the surface, with respect to 100 parts by weight of the polyvinylidene chloride resin,
Powder 0.01 to 0.20 parts by weight of at least one synthetic wax selected from the group consisting of polyethylene wax and acid capo triethylene wax, and at least one polyethylene selected from the group consisting of high density polyethylene and low density polyethylene A polyvinylidene chloride resin compound to which 0.01 to 0.20 parts by weight of resin powder is adhered ,
(I) The reduced viscosity of the polyvinylidene chloride resin is 0.035 to 0.070 liter / gram,
(Ii) The polyethylene wax has a melt viscosity of 10 to 1000 mPa · s measured at 140 ° C. using a B-type viscometer, a density measured according to JIS K6760 of 0.85 to 0.97 g / cm ³ , and , Having a characteristic that the melting point measured by a differential scanning calorimeter is 80 to 130 ° C.,
(Iii) The oxidized polyethylene wax is obtained by modifying the polyethylene wax by oxidation, and has an acid value measured according to JIS K5902 of 1 to 30 KOHmg / g,
(Iv) The high density polyethylene has a density measured according to ASTM D792 of 0.942 to 0.970 g / cm ³ , a melt flow rate measured at 190 ° C. according to ASTM D1238 of 0.1 to 20 g / 10 min, and The melting point measured by a differential scanning calorimeter is 120 to 140 ° C., and
(V) the low density polyethylene has a density measured according to ASTM D792 of 0.915 to 0.925 g / cm ³ , a melt flow rate measured at 190 ° C. according to ASTM D1238 of 0.05 to 50 g / 10 min, and The melting point measured by a differential scanning calorimeter is 100 to 115 ° C.
Polyvinylidene chloride resin compound . Heat stabilizer 0.05-6 parts by weight, plasticizer 0.05-10 parts by weight, film surface modifier 0.001-1 parts by weight with respect to 100 parts by weight of polyvinylidene chloride resin, but film surface modification When the agent is a scaly inorganic powder, it further contains 0.03 to 4 parts by weight and a colorant 0.001 to 3 parts by weight, provided that the proportion of the colorant is titanium oxide up to 10 parts by weight. 2. The polyvinylidene chloride resin compound according to claim 1.   2. The polyvinylidene chloride resin compound according to claim 1, wherein the other monomer copolymerizable with the vinylidene chloride is at least one monomer selected from the group consisting of vinyl chloride, methyl acrylate, and lauryl acrylate. .   2. The polyvinylidene chloride resin compound according to claim 1, wherein the polyvinylidene chloride resin is a powdered polyvinylidene chloride resin obtained by a suspension polymerization method.   Powder of at least one additive selected from the group consisting of a fatty acid calcium having 14 to 25 carbon atoms and an antioxidant with respect to 100 parts by weight of the polyvinylidene chloride resin on the surface of the powdered polyvinylidene chloride resin The polyvinylidene chloride resin compound according to claim 1, further comprising 0.001 to 0.20 parts by weight of a body. On the surface of the powdered polyvinylidene chloride resin, 100 parts by weight of the polyvinylidene chloride resin,
Powder 0.03 to 0.15 parts by weight of at least one synthetic wax selected from the group consisting of polyethylene wax and acid capo triethylene wax,
0.03 to 0.15 parts by weight of at least one polyethylene resin powder selected from the group consisting of high density polyethylene and low density polyethylene, and at least one additive selected from the group consisting of fatty acid calcium and antioxidant The polyvinylidene chloride resin compound according to claim 5, wherein 0.005 to 0.05 parts by weight of the powder is adhered. The antioxidant is triethylene glycol bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], dilauryl thiodipropionate, distearyl-3,3'-thiodipropio The polyvinylidene chloride resin compound according to claim 5 , which is at least one compound selected from the group consisting of nates and dibutylhydroxytoluene. As a film surface modifier, on the surface of the powdered polyvinylidene chloride resin, at least one inorganic powder selected from the group consisting of silicon dioxide and calcium carbonate with respect to 100 parts by weight of the polyvinylidene chloride resin 0 polyvinylidene chloride resin compound of claim 1, wherein .001～1 parts are worn with. The polyvinylidene chloride resin compound according to claim 8 , wherein a blending ratio of the inorganic powder is 0.03 to 0.50 parts by weight with respect to 100 parts by weight of the polyvinylidene chloride resin.   A biaxially stretched film formed from the polyvinylidene chloride resin compound according to claim 1. A two-layer structure in which a cylindrical film formed by biaxial stretching from a polyvinylidene chloride resin compound according to claim 1 by a inflation method is folded into a flat shape, and both ends are cut along the longitudinal direction. The biaxially stretched film according to claim 10 . It is a manufacturing method of the biaxially stretched film using the polyvinylidene chloride resin compound of Claim 1, Comprising: The following processes 1-4:
1) Step 1 of supplying the polyvinylidene chloride resin compound to an extruder and melt-extruding it from an annular die disposed at the tip of the extruder to form a molten parison;
2) Step 2 of quenching the molten parison obtained in Step 1;
3) Step 3 of re-heating the quenched parison to the stretching temperature; and 4) Step 4 of biaxial stretching by blowing a gas into the parison between the two pairs of pinch rollers to expand.
A method for producing a biaxially stretched film. Steps 5 and 6 below:
5) Step 5 of folding the cylindrical film obtained by biaxial stretching into a flat shape; and 6) Cutting both ends along the longitudinal direction of the folded film to form a biaxially stretched film having a two-layer structure. Step 6;
The manufacturing method of Claim 12 which further contains these. In the step 1, the polyvinylidene chloride resin compound is melt-extruded from an annular die at a resin temperature of 175 to 195 ° C. to form a tubular molten parison, and in the step 2, the molten parison is within a range of 3 to 15 ° C. Immersed in a cooling liquid maintained at a temperature to quench, and in step 3, the quenched parison is immersed in warm water maintained at a temperature in the range of 15-35 ° C. and reheated to the stretching temperature, and in step 4 , by blowing gas therein parison thermostatted, 2-5 times in the machine direction (MD), according to claim transverse (TD) to be inflated so as to be 2 to 5 times the draw ratio biaxially oriented 12 The manufacturing method as described. The manufacturing method of Claim 12 which obtains the biaxially stretched film whose thickness as a single layer film is 5-50 micrometers.

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