JP5369985B2 - Retort food packaging film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a food packaging film which is superior in heat resistance, stable heat sealability, food hygiene, and rupture resistance against dropping under a low-temperature condition or against an applied large external force. <P>SOLUTION: The retort food packaging film is a film containing a main constituent element of a block polyolefin resin composed mainly of a propylene-ethylene block copolymer. The food packaging film contains at least a phenolic antioxidant, a phosphorous-acid-based antioxidant, and an acrylate-based antioxidant, and includes a 20&deg;C xylene solubilized portion of 15 to 30 mass%. The film's drop rupture rate is 20% or less and retorted seal strength is 38 to 110 N/15 mm. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a film for food packaging, and more particularly to a film used for food packaging suitable for retort treatment as a film laminated with a substrate.

Films having heat sealing properties are widely used for packaging applications such as food packaging and fiber packaging. Especially for food packaging applications, after retort treatment after food filling, the form that is boxed, transported and sold over the counter is increasing in recent years, and a film that combines both sealing and heat resistance is required, Polypropylene film is used.
Furthermore, after the retort treatment as described above, there are many cases in which bag tearing due to freezing storage or dropping during freezing transport is regarded as a problem, and an improvement in bag breaking strength at low temperatures is also demanded.
A number of proposals have been made as a method for solving the above-described demand (see, for example, Patent Documents 1 to 4).

Japanese Patent Laid-Open No. 9-248885 JP 2000-143931 A JP 2000-186159 A JP 2002-302579 A

  Patent Document 1 includes 50 to 80% by mass of a polyolefin mainly composed of a propylene-ethylene block copolymer having a melting point of 140 to 165 ° C. and 50 to 20% by mass of a propylene copolymer having a melting point of 130 to 150 ° C. A retort polyolefin film obtained by blending 3 to 20 parts by mass of a thermoplastic elastomer to 100 parts by mass of a mixed resin is disclosed.

  In Patent Document 2, a specific amount of thermoplastic elastomer is blended with a polyolefin-based polymer mainly composed of a block polyolefin resin whose main component is a propylene-ethylene block copolymer having a melting point of 156 to 168 ° C. Heat resistance, stable heat sealability, food hygiene, and impact resistance at low temperatures by setting the intrinsic viscosity of the raw resin and the resulting film to a specific range. It is disclosed that a food packaging film having excellent burst resistance when dropped at low temperatures can be obtained.

  Patent Document 3 discloses a film for retort food packaging having good impact resistance, blocking resistance, and heat sealability at low temperatures by using a propylene-ethylene block copolymer obtained by a gas phase polymerization method as a raw material. Is disclosed.

  In Patent Document 4, an odor is obtained by using a resin composition containing 100 parts by weight of a polypropylene resin such as a propylene-ethylene block copolymer and 0.01 to 0.5 parts by weight of a specific phosphite. It is disclosed that a molded product for food packaging having excellent taste and impact strength can be obtained.

  However, recently, sterilization treatment at higher temperatures has been carried out, and the seal retention after such high temperature sterilization and the durability against external forces such as impact during transportation are resistant to rupture and seal. The demand for peelability is becoming more severe. In conventional films, by adding a thermoplastic elastomer, the bag breaking resistance is improved, but the sealing strength is not sufficient, and it is not sufficient in terms of bag breaking resistance when dropped or when a large force is applied. There was a problem.

  An object of the present invention is to provide a film for food packaging excellent in heat resistance, stable heat sealability, food hygiene, and bursting resistance when dropped at a low temperature or when a large external force is applied.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.

That is, the present invention is a film comprising, as a main component, a block polyolefin resin mainly composed of a propylene-ethylene block copolymer, and includes at least a phenol-based antioxidant, a phosphorous acid-based antioxidant, and an acrylate-based oxidation. An inhibitor is contained, the 20 ° C. xylene-soluble part is 15-30% by mass, the ratio of falling bags of the film is 20% or less, and the sealing strength after retorting is 38-110 N / 15 mm. It is a film for retort food packaging characterized by being.
In this case, a resin in which 85 to 97 parts by mass of a block polyolefin resin whose main component is a propylene-ethylene block copolymer having a 20 ° C. xylene soluble part of 5 to 20% by mass and 3 to 15 parts by mass of a thermoplastic elastomer is blended. It preferably consists of a composition.
Moreover, in this case, it is preferable that the Young's modulus in the lateral direction of the retort food packaging film is 430 to 750 Mpa or more.
Further, in this case, 95 to 97 parts by mass of a block polyolefin resin whose main component is a propylene-ethylene block copolymer having a 20 ° C. xylene soluble part of 5 to 20% by mass and 3 to 5 parts by mass of a thermoplastic elastomer. It is preferable to consist of the compounded resin composition.
Moreover, in this case, it is preferable that the Young's modulus in the lateral direction of the retort food packaging film is 560 to 750 Mpa or more.

According to the film for retort food packaging of the present invention, it has excellent sealing resistance, heat resistance, rupture resistance, food hygiene, and simultaneously satisfies the characteristics required as a retort food packaging film suitable for retort processing. Yes.
In particular, the seal strength after retort processing and the resistance to bag breakage when dropped or subjected to a large force at a low temperature are extremely excellent, so when used as a constituent material for packaging bags for retort foods, it provides excellent retort processing. In addition to having suitable characteristics, the reliability of durability against external forces such as impact of the packaging bag during storage and transportation of food after retort treatment is improved. Therefore, it can be suitably used as a constituent material of a food packaging film, particularly a retort food packaging bag.

  In the present invention, a film comprising a block polyolefin resin mainly composed of a propylene-ethylene block copolymer as a main component, wherein the 20 ° C. xylene soluble part is 15 to 30% by mass, The ratio of bag breakage is preferably 20% or less, and the seal strength after retorting is preferably 38 to 110 N / 15 mm.

  The bag drop resistance is a measure of burst resistance, and the lower the value of the bag drop resistance, the higher the reliability of durability against external force applied to the packaging bag, such as impact during transportation. Become. The falling bag breaking property is preferably 20% or less. It is more preferably 15% or less, and further preferably 10% or less. In particular, 5% or less is preferable.

  When the sealing strength after the retort treatment is less than 38 N / 15 mm, for example, when used as a sealant film for a packaging bag of retort food, seal leakage due to peeling of the sealing portion due to external force applied to the packaging bag due to impact during storage or transportation Reliability for occurrence prevention is reduced. The higher the sealing strength after the retort treatment, the higher the better. From the viewpoint of unsealing properties, the upper limit is preferably 110 N / 15 mm, and more preferably in the range of 38 to 60 N / 15 mm.

As mentioned above, as a method of improving the impact resistance of sealant films for packaging bags for retort foods and the bursting resistance when dropped at low temperatures, the rubber component is impacted by adding a rubber component to the polypropylene film. A method of improving by absorbing and dispersing the energy of external force such as the above has been adopted. Although this method is an effective method for improving impact resistance, it has a problem that the seal strength is lowered because the peel strength at the interface between the rubber component and the polypropylene resin as the matrix component is lowered. It was.
In other words, there has never been a film that itself has impact resistance and has sufficient heat seal strength even after retorting.

  By imparting the above properties, the balance between both properties is improved, and both properties can be compatible at a high level.For example, when used as a constituent material for packaging bags for retort foods, it has excellent properties suitable for retort processing. In addition, it has the ability to prevent the occurrence of seal leakage and rupture resistance due to external forces such as the impact of packaging bags during storage and transportation of food after retort processing, thereby improving the reliability of durability against external forces Can do.

  The polypropylene resin film of the present invention preferably has a Young's modulus in the transverse direction at 23 ° C. of 430 Mpa or more. 450 Mpa or more is more preferable. 430 Mpa is not preferable because the handleability of the film is lowered. By this measure, it is possible to suppress a decrease in the handleability of the film due to the absence of the above-mentioned lubricant or antiblocking agent. The upper limit is preferably about 750 MPa from the balance with other characteristics, and preferably in the range of 560 to 750 MPa.

In the present invention, in a film comprising a block polyolefin resin mainly composed of a propylene-ethylene block copolymer as a main component, the 20 ° C. xylene soluble part of the film is preferably 20 to 30% by mass, 22-28 mass% is more preferable.
Here, the 20 ° C. xylene-soluble part mainly reflects the amount of rubber contained in the film. If the 20 ° C. xylene-soluble part of the film is less than 20% by mass, the impact resistance of the film is lowered, and the falling bag breaking resistance of a packaging bag obtained using the film is not preferable. On the contrary, when it exceeds 30 mass%, since the sealing strength and transparency of a film fall, it is unpreferable.

  The polypropylene block copolymer resin in the present invention is a block copolymer of a copolymer component of a large amount of propylene and a small amount of ethylene and a copolymer component of a small amount of propylene and a large amount of ethylene. Yes, the molecular weight of each copolymer block is controlled at the polymerization stage. Specifically, as shown in JP-A No. 2000-186159, it is preferable to use one that is subjected to gas phase polymerization. That is, in the first step, a polymer part (component A) mainly composed of propylene is polymerized in the presence of an inert solvent, and then in the second step, the ethylene content is 20 to 50% by weight in the gas phase. A block copolymer obtained by polymerizing a copolymer part (component B) of propylene and ethylene is exemplified, but is not limited thereto.

As a method for bringing the amount of the 20 ° C. xylene soluble part of the above film into the above range, when the above polypropylene block copolymer is used alone or when the above polypropylene block copolymer is mixed with another thermoplastic elastomer Is mentioned.
The amount of the 20 ° C. xylene soluble part of the film has a correlation with the total content of the B component and the thermoplastic elastomer component of the polypropylene block copolymer. For example, when the polypropylene block copolymer is used alone, The method of making the quantity of a 20 degreeC xylene soluble part of a polypropylene-type block copolymer resin 20-30 mass% is mentioned.
At this time, even if the ethylene content in the polypropylene block copolymer is the same, it varies depending on the copolymerization ratio of ethylene-propylene in the A component and the B component, and thus needs to be adjusted as appropriate.

  The melt flow rate (MFR) of the polypropylene block copolymer resin is preferably 1 to 10 g / 10 min, and more preferably 2 to 7. If it is less than 1 g / 10 minutes, the viscosity is too high and extrusion with a T-die is difficult. Conversely, if it exceeds 10 g / 10 minutes, the stickiness of the film and the impact strength (impact strength) of the film are inferior. This is because problems arise.

As a parameter that the difference between the intrinsic viscosity [η] _{CXS of} a part mainly composed of a rubber component of the polypropylene block copolymer and the part [η] _CXIS mainly composed of a polypropylene component _affects the heat seal strength, [η] _CXS is A range of 1.8 to 3.8 (dl / g) is preferable. More preferably, it is in the range of 2.0 to 3.0 (dl / g). If it exceeds 3.0 (dl / g), fish eyes are likely to occur. On the other hand, if it is 1.8 (dl / g) or less, the seal strength is remarkably lowered. [Η] _{CXIS at} that time is preferably in the range of 1.0 to 3.0 (dl / g). If it exceeds 3.0 (dl / g), the viscosity is too high and extrusion with a T-die is difficult. Conversely, if it is less than 1.0 (dl / g), stickiness of the film or film This is because problems such as poor impact resistance (impact strength) occur.

The above [η] _{CXS and} [η] _CXS are values obtained by the following measuring method.
After completely dissolving 5 g of the sample in 500 ml of boiling xylene, the temperature was lowered to 20 ° C. and left for 4 hours or more. Thereafter, this was separated into a precipitate (CXIS part) and a solution, the filtrate was dried and dried at 70 ° C. under reduced pressure, and then the obtained solid (20 ° C. xylene-soluble part (CXS)). The intrinsic viscosity ([η]) was measured in tetralin at 135 ° C. using an Ubbelohde viscometer.

In general, it is known that there is a correlation between the MFR and the intrinsic viscosity η of the entire film. By knowing the η of the film, the MFR of the resin used can be known. η is a measure of molecular weight, and the larger the value, the larger the molecular weight, and the smaller the value, the smaller the molecular weight. MFR is a measure of molecular weight. The smaller the value, the larger the molecular weight, and the larger the value, the smaller the molecular weight.

The polypropylene block copolymer resin having a 20 ° C. xylene soluble part amount higher than 20% by mass may be difficult to handle. Therefore, for example, a resin composition in which 85 to 95 parts by mass of a block polyolefin resin mainly composed of a propylene-ethylene block copolymer having a 20 ° C. xylene soluble part of 5 to 20% by mass and 5 to 15 parts by mass of a thermoplastic elastomer is blended. It is preferable in terms of handleability to use a product, more preferably 7 to 18 parts by mass of a 20 ° C. xylene-soluble part of a block polyolefin resin mainly composed of a propylene-ethylene block copolymer, and further 12 to 18 parts by mass preferable.
Further, the blending amount of the block polyolefin resin mainly composed of the propylene-ethylene block copolymer is more preferably 87 to 93 parts by mass, and the blending amount of the thermoplastic elastomer is more preferably 7 to 13 parts by mass.

  Examples of the thermoplastic elastomer include an α-olefin copolymer resin, more specifically, an ethylene / α-olefin copolymer resin, a hydrogenated block copolymer, and the like.

The ethylene / α-olefin copolymer resin is obtained by copolymerizing ethylene and an α-olefin having 3 to 12 carbon atoms using a metallocene catalyst, and has a melt flow rate (MFR) of 0.1 to 10 g. / 10 minutes, a density of 0.820 to 0.930 g / cm ³ (measured by ASTM D 1505) and a molecular weight distribution (Mw / Mn) determined by GPC method of 1.3 to 6.0 are used. Is a desirable form.

The α-olefin is specifically an alkene having a carbon-carbon double bond at the α-position. Alkenes are unsaturated hydrocarbons and are represented by C _n H _2n . For example. If n = 3, it is propylene, and two of the three carbons have a double bond between two carbons, one of which is a π bond and one is a σ bond. In addition, the π bond portion tends to cause an addition reaction because the bond energy is small.

  The hydrogenated block copolymer is composed of a polymer block A mainly composed of at least one vinyl aromatic compound and a copolymer block B mainly composed of at least one hydrogenated conjugated diene compound. For example, it is a hydrogenated block copolymer composed of ABA, BABA, BABA, and a mixture thereof. And what contains 10-40 mass% of vinyl aromatic compounds can be used as this hydrogenated block copolymer.

  As the vinyl aromatic compound constituting the hydrogenated block copolymer, for example, styrene, α-methylstyrene, and the like can be used, and styrene is particularly preferable. As the conjugated diene compound before hydrogenation constituting the hydrogenated conjugated diene compound, for example, butadiene, isoprene, or 1-3 pentadiene can be used, and butadiene is particularly preferable. The olefinic compound polymer block B is preferably obtained by hydrogenating 80%, preferably 90% or more of the aliphatic double bond based on the conjugated diene compound of the vinyl aromatic compound-conjugated diene compound block copolymer. A typical example of the copolymer is a styrene-ethylene-butylene-styrene copolymer, and the copolymerization amount of styrene is preferably 10 to 30% by weight. From the viewpoint of transparency, 10 to 20% by weight is preferred.

The melt flow rate (MFR) of the thermoplastic elastomer is preferably 5 g / 10 min or less, preferably 0.2 to 5 g / 10 min in terms of impact resistance at low temperatures.
The difference between the melt flow rate (MFR) of the thermoplastic elastomer and the melt flow rate (MFR) of the polypropylene block copolymer resin is preferably from 0.1 to 7 in terms of uniform kneading and preventing fish eye, and preferably Is 1-4.
In addition, the intrinsic viscosity (η) of the thermoplastic elastomer is preferably 1.0 to 5.0, and preferably 1.2 to 5.0 in terms of maintaining uniform seal strength, impact strength, and bag drop strength. 3.0.
The difference between the intrinsic viscosity (η) of the thermoplastic elastomer and the intrinsic viscosity (η) of the polypropylene block copolymer resin is preferably 1.0 to 5.0 in terms of uniform kneading and preventing fish eyes, and preferably Is 1.0-3.0.

  In the present invention, it is preferable to use an ethylene / α-olefin copolymer resin from the viewpoint of bleeding of low molecular weight materials and transparency.

Although the method for imparting the above properties is not limited, a method for optimizing the composition of the polypropylene resin constituting the film and the composition of the antioxidant is a preferred embodiment. It is preferable to comprise three types of antioxidants of phosphoric acid type and acrylate type. The total amount of the antioxidant at this time is preferably 1500 to 3500.
The function of each antioxidant is as follows. The acrylate antioxidant has a function of capturing the radical “R.” generated by heat and shearing and returning it to “RH” in the extruder. The phenolic antioxidant is said to be a primary antioxidant, and has a function of capturing “R ··” with oxygen (O 2) to capture the radical “ROO ·” to “ROOH”. Phosphorous acid system has a phenolic antioxidant part and a phosphoric acid antioxidant part in the molecule, and it functions as a phosphorus antioxidant while acting as a phenolic antioxidant. Has excellent performance.

  Phosphite antioxidants include phosphites represented by the following general formula (I).

In the phosphites represented by the general formula (I), the substituents R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or 5 carbon atoms. Represents a cycloalkyl group having 8 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group.

  Here, as a representative example of an alkyl group having 1 to 8 carbon atoms, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, Examples thereof include t-butyl group, t-pentyl group, i-octyl group, t-octyl group, 2-ethylhexyl group and the like. Typical examples of the cycloalkyl group having 5 to 8 carbon atoms include, for example, cyclopentyl group, cyclohexyl. Group, cycloheptyl group, cyclooctyl group and the like, and typical examples of the alkylcycloalkyl group having 6 to 12 carbon atoms include, for example, 1-methylcyclopentyl group, 1-methylcyclohexyl group, 1-methyl-4- i-propylcyclohexyl group and the like, and typical examples of the aralkyl group having 7 to 12 carbon atoms include, for example, benzyl group and α-methylbenzyl group. alpha, alpha-dimethylbenzyl group and the like.

R ¹ , R ² and R ⁴ are preferably an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, and an alkylcycloalkyl group having 6 to 12 carbon atoms. Among these, R ¹ and R ⁴ are more preferably a t-butyl group, a t-pentyl group, a t-octyl group such as a t-octyl group, a cyclohexyl group, or a 1-methylcyclohexyl group.

R ² is more preferably carbon such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, t-pentyl group, etc. An alkyl group having 1 to 5 atoms, more preferably a methyl group, a t-butyl group, or a t-pentyl group.

R ⁵ is preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms, more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, i -An alkyl group having 1 to 5 carbon atoms such as a propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, t-pentyl group.

The substituent R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl groups as described above. Preferably they are a hydrogen atom or a C1-C5 alkyl group, More preferably, they are a hydrogen atom or a methyl group.

  Substituent X, when n is 0, represents that two groups having a phenoxy group skeleton are directly bonded, and when n is 1, a sulfur atom or an alkyl group having 1 to 8 carbon atoms. Or the methylene group which the C5-C8 cycloalkyl group may substitute is represented. Here, examples of the alkyl group having 1 to 8 carbon atoms and the cycloalkyl group having 5 to 8 carbon atoms substituted on the methylene group include the same alkyl groups and cycloalkyl groups as described above. As the substituent X, preferably n is 0 and a group having two phenoxy group skeletons is directly bonded, or n is 1, and a methylene group, a methyl group, an ethyl group, or an n-propyl group. , I-propyl group, n-butyl group, i-butyl group, t-butyl group and the like are substituted methylene groups.

Substituent A is an alkylene group having 2 to 8 carbon atoms or * -CO (R ⁷ ) m-group (R ⁷ is an alkylene group having 1 to 8 carbon atoms, and * is a bonding site with an oxygen atom. And m is 0 or 1.

Here, as typical examples of the alkylene group having 2 to 8 carbon atoms, for example, ethylene group, propylene group, butylene group, pentamethylene group, hexamethylene group, octamethylene group, 2,2-dimethyl-1,3- A propylene group etc. are mentioned, Preferably it is a propylene group. The * -COR 7 ^- * in group indicates that the carbonyl group is a moiety that binds to the oxygen atom of the phosphite group. As typical examples of the alkylene group having 1 to 8 carbon atoms in R ⁷ , for example, a methylene group, an ethylene group, a propylene group, a butylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, 2,2-dimethyl- Examples include 1,3-propylene group. * -CO (R ⁷ ) m- group, preferably m is 0 * -CO- group, or m is 1 and R ⁷ is ethylene * -CO (CH ₂ CH ₂ )-group It is.

  One of Y and Z represents a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. .

  Here, examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl groups as described above. Examples of the alkoxy group having 1 to 8 carbon atoms include an alkyl moiety having the above-described alkyl having 1 to 8 carbon atoms. The alkoxy group which is the same alkyl is mentioned, and the aralkyloxy group having 7 to 12 carbon atoms includes, for example, an aralkyloxy group in which the aralkyl moiety is the same aralkyl as the aralkyl having 7 to 12 carbon atoms.

  The phosphites represented by the above general formula (I) are 2,4,8,10-tetra-tert-butyl-6- [3- (3-methyl-4-hydroxy-5-tert-butylphenyl). Propoxy] dibenzo [d, f] [1,3,2] dioxaphosphine is preferred. It is preferable to use Sumitizer GP (registered trademark) manufactured by Sumitomo Chemical Co., Ltd.

  The blending amount of the above phosphites in the present invention is preferably in the range of 100 to 1000 ppm with respect to the total polypropylene resin composition described above. 200 to 800 ppm is more preferable, and 300 to 700 ppm is more preferable.

  The acrylate antioxidant of the present invention is an antioxidant having a phenol derivative containing an acrylate residue in the molecule, and includes those having a structure represented by the following formula (II).

In the formula (II), R ⁶ is an alkyl group having 1 to 5 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a t-butyl group, and a 2,2-dimethylpropyl group. A methyl group or an ethyl group is preferable, and an ethyl group is more preferable.

In the formula (II), R ⁷ is an alkyl group having 1 to 8 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a t-butyl group, a t-pentyl group, and a t-octyl group. It is done. A methyl group, a t-butyl group or a t-pentyl group is preferred, and a t-pentyl group is more preferred.

In the formula (II), R ⁸ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and examples thereof include a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and an octyl group. . Preferably they are a hydrogen atom or a methyl group, More preferably, it is a methyl group.

In the formula (II), R ⁹ is a hydrogen atom or a methyl group. Preferably it is a hydrogen atom.

  Examples of the acrylate compound include 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate, 2,4-di- t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) butyl] phenyl acrylate, 2,4-di-t-amyl-6- [1- (3,5- Di-t-amyl-2-hydroxyphenyl) propyl] phenyl acrylate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, and the like. .

  Preferably, 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate and 2-t-butyl-6- (3- t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate.

  As said acrylate compound, it can select from a commercially available thing suitably and can be used. For example, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, Sumitizer GM (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., 2,4- Sumitizer GS (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., which is di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate, can be exemplified. . In particular, it is preferable to use a Sumilizer GS (registered trademark).

  The blending amount of the acrylate antioxidant in the present invention is preferably in the range of 100 to 1000 ppm with respect to the total polypropylene resin composition. 200 to 800 ppm is more preferable, and 300 to 700 ppm is more preferable.

  The phenolic antioxidant used in the present invention is an antioxidant having a phenol derivative in the molecule, such as 2,6-di-t-butyl-4-methylphenol, 2,6-di-t. -Butyl-4-ethylphenol, 2,6-dicyclohexyl-4-methylphenol, 2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol 2,6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol, 2-t-butyl-2-ethyl-6-t-octylphenol, 2-isobutyl-4-ethyl -6-t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isopropylphenol, dl-α-tocopherol, t-butyl Ruhydroquinone, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-) 6-t-butylphenol), 2,2-thiobis (4-methyl-6-t-butylphenol), 4,4′-methylenebis (2,6-di-t-butylphenol), 2,2′-methylenebis [6 -(1-methylcyclohexyl) -p-cresol], 2,2′-ethylidenebis (4,6-di-t-butylphenol), 2,2′-butylidenebis (2-t-butyl-4-methylphenol) ,

  2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t-pentyl) Phenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2 , 2-thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl) -4-hydroxy-hydrocinnamide), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, tris (2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, tris [(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxyethyl] isocyanurate, tris (4-t- Butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate, 2,4-bis (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5 -Triazine, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate Methane, 2,2′-methylenebis (4-methyl-6-tert-butylphenol) terephthalate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxy Benzyl) benzene, 3,9-bis [1,1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl] -2,4,8,10 -Tetraoxaspiro [5,5] undecane, 2,2-bis [4- (2- (3,5-di-t-butyl-4-hydroxyhydrocinnamoyloxy)) ethoxyphenyl] propane, β- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionic acid stearyl ester and the like.

  Preferably, β- (3,5-di-t-butyl-4-hydroxyphenyl) propionic acid stearyl ester, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Methane, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4- Hydroxybenzyl) benzene, dl-α-tocopherol, tris (2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, tris [(3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionyloxyethyl] isocyanurate, 3,9-bis [1,1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy-5-methyl) Butylphenyl) propionyloxy} ethyl] -2,4,8,10-tetra-oxa-spiro [5,5] undecane.

  Commercially available products may be used as the phenolic antioxidant used in the present invention. For example, Irganox 1010 (manufactured by Ciba Specialty Chemicals), Irganox 1076 (manufactured by Ciba Specialty Chemicals) ), Irganox 1330 (manufactured by Ciba Specialty Chemicals), Irganox 3114 (manufactured by Ciba Specialty Chemicals), Irganox 1425WL (manufactured by Ciba Specialty Chemicals), and the like.

  In these, it is preferable to use together 2 types of phenolic antioxidants from which molecular weight differs. Although this combination is not limited, for example, two types of Irganox 1010 (Ciba Specialty Chemicals, Inc., molecular weight 1178) and Irganox 1076 (Ciba Specialty Chemicals, Inc., molecular weight 531) are used in combination. Is preferred. The reason why the effect of the present invention is more remarkably expressed by the combination is not clear, but, for example, by using an antioxidant having a molecular weight of 1000 or less, familiarity with the rubber component is improved and the rubber component is deteriorated. It is conjectured that the circularity of the island formed by the rubber component is suppressed and the sealing strength is improved as a result.

  The blending amount of the phenolic antioxidant in the present invention is preferably in the range of 500 to 5000 ppm with respect to the total polypropylene resin composition. 1000 to 4000 ppm is more preferable, and 1500 to 3000 ppm is more preferable. In particular, 2000 to 3000 ppm is preferable.

  In the present invention, it is a more preferable embodiment that another type of phosphoric acid-based antioxidant other than the phosphorous acid type is used in combination with the above three types of antioxidant systems.

  As a specific example of another phosphorus antioxidant used in the present invention, for example, a heat containing a trivalent phosphorus atom in the molecule and having at least one P—O—C bond. Stabilizers can be mentioned. For example, tributyl phosphite, trioctyl phosphite, trilauryl phosphite, tristearyl phosphite, tridecyl phosphite, tricresyl phosphite, tricyclohexyl phosphite, triphenyl phosphite, trilauryl thiophosphite, tris ( 2-ethylhexyl) phosphite, tris (isodecyl) phosphite, tris (tridecyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, tris (butoxyethyl) phosphite, tris (nonylphenyl) Phosphite, tris (3,5-di-t-butyl-4-hydroxyphenyl) phosphite, tris [4,4′-isopropylidenebis (2-t-butylphenol)] phosphite, tris (1,3- Gieste (Royloxyisopropyl) phosphite, 2-ethylhexyl diphenyl phosphite, decyl diphenyl phosphite, phenyl di-2-ethylhexyl phosphite, phenyl didecyl phosphite, phenyl diisodecyl phosphite, phenyl di (tridecyl) phosphite, diphenyl nonyl phosphite, Diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl mono (tridecyl) phosphite, dibutyl hydrogen phosphite, 4,4′-isopropylidene diphenol alkyl (C12 to C15) phosphite, 4,4′-butylidenebis ( 3-methyl-6-tert-butylphenyl) di-tridecyl phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl Sufite, 2,2'-ethylidenebis (4,6-di-t-butylphenol) fluorophosphite, bis (2,4-di-t-butyl-6-methylphenyl) .ethyl phosphite, 4,4 ' -Isopropylidenebis (2-t-butylphenol) di (nonylphenyl) phosphite, distearyl pentaerythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, diphenylpentaerythritol diphosphite, phenyl 4, 4'-isopropylidenediphenol pentaerythritol diphosphite, bis (4,6-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) Pentaerythritol diphosphite, phenyl -Bisphenol A pentaerythritol diphosphite, tetraphenyldipropylene glycol diphosphite, tetra (tridecyl) -1,1,3-tris (2-methyl-5-tert-butyl-4-hydroxyphenyl) butanediphos Phyto, tetra (C12-C15 mixed alkyl) -4,4′-isopropylidene diphenyl diphosphite, tetra (tridecyl) -4,4′-butylidenebis (3-methyl-6-tert-butylphenol) diphosphite, tetrakis (4 , 6-Di-t-butylphenyl) -4,4′-biphenylene diphosphonite, tetrakis (2-methyl-4,6-di-t-butylphenyl) -4,4′-biphenylene diphosphonite Bis (octylphenyl) -bis [4,4′-butylidenebis (3-methyl) 6-t-butylphenol)] • 1,6-hexanediol diphosphite, hydrogenated-4,4′-isopropylidene diphenol polyphosphite, 9,10-di-hydro-9-oxa-9-oxa- 10-phosphaphenanthrene-10-oxide, 2-[{2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo (D, F) (1,3,2) -dioxaphos Fephin-6-yl} oxy] -N, N-bis [2-[{2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo (D, F) (1,3,2) -Dioxaphosphine-6-yl} oxy] ethyl] ethanamine, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5-t-butylphenyl) butane, 3,4 , 5,6-Tetraben Like 1,2-oxa phosphane-2-oxide.

  Preferably, those having no pentaerythritol skeleton, tris (2,4-di-t-butylphenyl) phosphite, tris (3,5-di-t-butyl-4-hydroxyphenyl) phosphite, Bis (2,4-di-t-butyl-6-methylphenyl) .ethyl phosphite, tetrakis (2-methyl-4,6-di-t-butylphenyl) -4,4'-biphenylenediphosphonite It is.

  Commercially available products may be used as the phosphorus-based antioxidant used in the present invention. For example, Irgaphos 168 (Ciba Specialty Chemicals Co., Ltd.), Irgaphos 38 (Ciba Specialty Chemicals Co., Ltd.), Examples include GSY-P101 (manufactured by Yoshitomi Fine Chemical Co., Ltd.), Ultranox 641 (manufactured by GE Specialty Chemicals Co., Ltd.), and the like.

  The blending amount of the phosphorus antioxidant in the present invention is preferably in the range of 500 to 5000 ppm with respect to the total polypropylene resin composition. 1000 to 4000 ppm is more preferable, and 1500 to 3000 ppm is more preferable.

  The above phosphorus antioxidant is made into “ROOH” by the primary antioxidant, but it is still unstable and “RH” acts on it, and it is easy to generate “R · + ROOH” and radicals. It has the function of changing to a stable “ROH” and inactivating it, and its synergistic effect is exhibited.

  Further, in addition to the above four kinds of antioxidants, for example, an antioxidant having another structure such as a sulfur-based antioxidant may be further used in combination.

  The method for preparing a polypropylene resin composition containing the antioxidant and other additives used in the present invention is, for example, a method of heat-melt kneading using a kneader such as a kneader, a Banbury mixer, or a roll, uniaxial or Examples thereof include a method of heat-melt kneading using a twin screw extruder or the like. Various resin pellets may be dry blended. In the method for preparing the composition, the antioxidant and the crystal nucleating agent may be added directly to the respective powders, or may be added as a master batch previously mixed with the polypropylene resin. When adding as a masterbatch, it may be prepared for each additive or may be prepared by mixing two or more. Moreover, you may implement combining the commercially available resin in which the said additive was mix | blended well. In addition, the composition may be prepared in advance to be supplied to a film forming process and supplied to a film forming extruder, or the components constituting the composition may be supplied to the film forming extruder. It may be supplied and prepared to form a film.

  The extruded film of the present invention is an unstretched film formed by a known method such as a T-die method or an inflation method, and the thickness of the film is not particularly limited, but is generally 1 to 500 μm. A preferable thickness is selected as necessary.

  As film forming conditions for using the polypropylene resin composition of the present invention as an extruded film, for example, in the case of the T-die method, it is preferable to carry out at a cooling roll temperature of 60 to 90 ° C. 65-85 degreeC is more preferable. When the cooling roll temperature is less than 60 ° C., the rigidity of the resulting film is not preferable. On the contrary, when it exceeds 90 ° C., a touch roll mark of the cooling roll is generated, which is not preferable. In addition, transparency may be reduced.

  The bag-breaking resistance and seal strength described above are affected by the degree of kneading of the raw material resin composition in the extrusion process of film formation. Increasing the degree of kneading improves the spherical dispersibility of the rubber component, but also promotes the deterioration of the resin including the rubber component, which adversely affects the bag breaking resistance and the sealing strength described above. In particular, it greatly affects the seal strength. Therefore, in the present invention, it is preferable to avoid excessive kneading in the extrusion process of film formation.

In this invention, it is preferable to implement on the following extrusion conditions.
Extrusion process temperature: 230 to 280 ° C., screw length / screw diameter of extruder screw: 20 to 70, extruder screw rotation speed: 30 to 60 rpm, supply pressure to die 10 to 16 Mpa, extruder outlet pressure: 29 to 36 Mpa .

  The extruded film of the present invention can be subjected to surface treatment such as corona discharge treatment or flame treatment by a method generally employed industrially.

In this invention, it is preferable to use said retort food wrapping required film as a laminated body which consists of a biaxially stretched polyester film and aluminum foil.
With this configuration, it can be suitably used as a packaging material for retort food represented by retort curry.

  The said retort food packaging required film of this invention can also be used as a laminated body with films, such as a polyamide biaxially stretched film.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, but may be implemented with appropriate modifications within a scope that can meet the gist of the present invention. These are all included in the technical scope of the present invention.

  The measurement and evaluation methods employed in this specification are as follows.

1. Melt flow rate [MFR]
According to JIS K7210, it was measured by the method of Condition-14 (load 2.16 kg, temperature 230 ° C.).

2. Melting point About 6 mg of propylene-based copolymer (C) was weighed, and increased to 200 ° C. at a rate of temperature increase of 10 ° C./min using a differential scanning calorimeter (type 5200) manufactured by Seiko Denshi Kogyo Co., Ltd. Warming and holding at 200 ° C. for 5 minutes, then cooling rate: cooling rate to 0 ° C. at 100 ° C./min, temperature rising rate; melting curve when the temperature is raised from 0 ° C. to 200 ° C. at 10 ° C./min From this melting curve, the method of JIS-K-7121 9.1 was followed, and the temperature at the top of the melting peak on the highest temperature side was melted from the melting curve.

3. Ratio of xylene soluble part at 20 ° C. (% by mass)
After 5 g of the sample was completely melted in 500 ml of boiling xylene, the temperature was lowered to 20 ° C. and left for 4 hours or more. Thereafter, the precipitate and the solution were separated by filtration, and the filtrate was dried and dried at 70 ° C. under reduced pressure. From the mass of the obtained dried product, the 20 ° C. xylene-soluble part amount was measured, and the ratio was determined.

4. Ethylene content Measured by ¹³ C-NMR method according to the method described on page 616 of Polymer Handbook (1995, published by Kinokuniya Shoten).

5, Haze value Based on JIS-K-6714, it measured using "Haze Tester J" made by Toyo Seiki Seisakusho.

6. Seal strength after retort treatment The seal part of the water-filled bag retort-treated by the above method is cut to a width of 50 mm in the vertical direction and a width of 15 mm, and in accordance with JIS K7127-1989, test speed H: 200 mm / min. Measure the seal strength at a speed of. Each side of the bag was measured at n = 5, and the average value was displayed. As a measuring device, Toyo Baldwin Co., Ltd. universal tensile testing machine TENSILON / STM-T-50BT is used.

7). Evaluation of drop bag breakage resistance A polyester adhesive was applied in advance to a corona-treated surface (48 mN / m or more) of a 12 μm biaxially stretched polyester film (E5100 manufactured by Toyobo Co., Ltd.). A laminate of 5 μm aluminum foil (manufactured by Sumi Light Aluminum Foil Co., Ltd., for food packaging (for retort use)) and aged at 40 ° C. for 5 days is prepared.
A polyester adhesive is applied to the aluminum foil surface of the laminate, and the corona treatment of the 70 μm-thick polypropylene resin film for corona treatment (wet tension of 48 mN / m or more) is applied to the coated surface. The surface of the agent was laminated so as to be in contact with each other, and a laminate film was obtained by aging at 40 ° C. for 5 days.
Both of the polyester-based adhesive and the catalyst used in the production of the laminate film are TM590 and CAT56 manufactured by Toyo Morton Co., Ltd. Both were applied by the following method.
TM590: 15 kg, CAT56: 2.4 kg, and ethyl acetate 25.3 kg are mixed and sufficiently stirred to make a uniform liquid, and the time is adjusted to 12.7 seconds with Zahn cup # 3. (Equivalent to 25% non-volatile content) Using this solution, using a 1000 coating test machine UCT-2500 manufactured by Musashino Machine Design Office Co., Ltd., coated with a 100 l × 90 μm / inch gravure roll, dried at 80 ° C., It is applied so that the solid content is 3 g / m ² .
The laminate film prepared by the above method was formed into a bag under the following conditions using a test sealer (product number: custom-made product, LOT: A56430, DATE: 670670) manufactured by Seibu Kikai Co., Ltd.
After the temperature of the bar reaches 270 ° C. in advance, the blanking is performed 30 times or more, and the lower bar is heated. Seal temperature: 270 ° C. × 2 kg × 1 second, cooling bar: water temperature × 2 kg X Perform in 1 second. After the seal is struck, it is always performed once before the next seal is struck. In this way, a bag sealed on three sides of 130 mm × 165 mm (sealing width: 5 mm) was produced.
200 g of water was put into the bag, and the entire surface was sealed by impulse sealing under the conditions of a vacuum level of 90%, a sealing time of 2 seconds, and a cooling time of 1 second using a product made by Tosei Corporation (TOSPACK V-602G-2). Make a water-filled bag.
The water-filled bag was treated with a hot water retort treatment machine (RCS-60SPXTG) manufactured by Nisaka Manufacturing Co., Ltd. at a pressure of 0.2 MPa at 120 ° C. for 30 minutes (condition: temperature increase 30 ° C. → 120 ° C .: 10 minutes) 120 ° C .: 30 minutes, cooling 120 => 30 ° C .: 10 minutes), and the retort treatment was performed. The water-filled bag subjected to the retort treatment is packed in a cosmetic box having a longitudinal direction of 160 mm, a lateral direction of 130 mm, and a thickness direction of 20 mm, and further, the cosmetic box is composed of one longitudinal direction, three lateral directions, and 12 depth directions. Collected and packed in a collection box. After storing it at 5 ° C for 24 hours or more, from the height of 1.6m at room temperature (from the concrete floor to the bottom of the box packed and packed), the vertical direction of the vanity box is the falling direction, and the top and bottom are alternated Instead of dropping 10 times continuously, find the percentage of bags torn. It carries out by n = 3 and displays it as an average value.
The evaluation criteria were as follows.
(Double-circle): The ratio of the torn bag is 10% or less,
○: Ratio of torn bags is 11 to 20% ×: Ratio of torn bags exceeds 20%

8). Seal strength after retort treatment The seal portion of the water-filled bag retort-treated by the above method is cut to a width of 50 mm in the vertical direction and a width of 15 mm, and in accordance with JIS K7127-1989, the test speed H is a speed of 200 mm / min. Measure the seal strength with. As the measuring device which measured each side of the bag with n = 5 and displayed the average value, a universal tensile tester TENSILON / STM-T-50BT manufactured by Toyo Baldwin Co., Ltd. was used.

9. Young's modulus In accordance with JIS K7127, sample shape conforming to No. 1 type test piece (sample length 200 mm, sample width 15 mm, distance between chucks 100 mm), MD direction under conditions of crosshead speed 500 mm / min It measured at 23 degreeC about (film longitudinal direction).

Example 1
0.05% by mass of Irgafos 168 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phosphorus antioxidant and Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phenolic antioxidant Block copolymerized polypropylene resin having an ethylene content of 20% by mass and an ethylene content of 7% by mass and a 20 ° C. xylene soluble part of 15% by mass (MFR = 3.0 g / 10 min, WFS 5293-22 manufactured by Sumitomo Chemical Co., Ltd.) 86 mass parts, ethylene / propylene copolymer resin-based thermoplastic elastomer containing 0.05% by mass of Irganox 1076 (manufactured by Ciba Specialty Chemicals Co., Ltd.) (MFR = 0.7 g / 10 min, Mitsui Chemicals, Inc.) Company made, P0680) 12 parts by mass, 4% by mass of ethylene random polypropylene random co Master batch resin (Sumitomo Chemical Co., Ltd. MA180, MFR = 10 g / min) 1 part by mass and ethylene containing 5% by mass of a phosphite-based antioxidant Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.) in the combined resin Masterbatch resin (MA181 manufactured by Sumitomo Chemical Co., Ltd., MFR = 10 g / m) containing 4% by mass of polypropylene random copolymer resin and 5% by mass of Sumylizer GS (manufactured by Sumitomo Chemical Co., Ltd.) which is an acrylate antioxidant. Min) 1 part by mass was melt-extruded with a T-die film forming machine to obtain an unstretched film having a cooling roll temperature of 55 ° C. and a thickness of 70 μm. The extruder screw is a single layer type with L / D = 29. The number of revolutions of the extruder was 55 rev / min, the die was a flexible, hanger coat type, and a single layer die with a die width of 4550 mm was used. The extruder temperature setting is hopper inlet side: 230 ° C., the extruder outlet side: 235 ° C., the die temperature setting is 240 ° C., the filtration area is 1703 cm 2 between the extruder outlet and the die, and the opening ratio is 23% (4 mmφ) × 3116 392cm2) # 20 mesh (wire mesh) # 50 mesh (wire mesh), NF-13D (Naslon filter 13D), # 150 mesh (wire mesh) # 100 mesh (wire mesh) (all manufactured by Nippon Seisen Co., Ltd.) ) Filters combining each one were installed, and the raw resin composition was filtered. The cooling roll temperature (chill roll) temperature was set to 55 ° C. to obtain a 70 μm film. The film was wound on a bobbin, placed on a mill stand at 30 ° C. for 24 hours, and after aging, processing and evaluation were performed.
The results are shown in Table 1.
The food packaging film obtained in this example had good properties with all the properties shown in Table 1 and high quality.

(Comparative Example 1)
In the method of Example 1, the blending of the ethylene / propylene copolymer resin-based thermoplastic elastomer (MFR = 0.7 g / 10 min, Mitsui Chemicals, P0680) was canceled, and the block copolymerized polypropylene resin blending amount was A food packaging film of Comparative Example 1 was obtained in the same manner as in Example 1 except that the content was changed to 98 parts by mass. The results are shown in Table 1.
The film for food packaging obtained in Comparative Example 1 was inferior in dropping bag resistance and low quality.

(Comparative Example 2)
In the method of Example 1, the amount of ethylene-propylene copolymer resin-based thermoplastic elastomer (MFR = 0.7 g / 10 min, manufactured by Mitsui Chemicals, P0680) is 20 parts by mass, and block copolymerized polypropylene. A food packaging film of Comparative Example 2 was obtained in the same manner as in Example 1 except that the resin content was changed to 78 parts by mass. The results are shown in Table 1.
Since the food packaging film obtained in this Comparative Example 2 has a large amount of elastomer, the amount of soluble part at 20 ° C. xylene increases, and the amount of polypropylene that contributes to the sealing strength is reduced although the drop-off bag breaking resistance is improved. The seal strength after retort treatment was low and the quality was low.

(Comparative Example 3)
In the method of Example 1, a master batch resin obtained by blending a polypropylene random copolymer resin (melting point 142 ° C.) having an ethylene amount of 4% by mass with a phosphite antioxidant Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.). Master batch resin (Sumitomo Chemical Co., Ltd. MA181, MFR = 10 g / min) blended (Sumitomo Chemical Co., Ltd. MA180, MFR = 10 g / min) and acrylate antioxidant Sumilizer GS (Sumitomo Chemical Co., Ltd.) The film for food packaging of Comparative Example 3 was obtained in the same manner as in Example 1 except that the blending of (ii) was stopped and the blending amount of the block copolymer polypropylene resin was changed to 88 parts by mass. The results are shown in Table 1.
Since the film for food packaging obtained in this Comparative Example 3 has no post-added antioxidant, the resin deteriorates, and the surface area of polypropylene that contributes to the sealing strength is reduced, so the sealing strength after retorting is low and the quality is low. there were. Moreover, blocking resistance was also inferior to the film for food packaging obtained in Example 1.

(Comparative Example 4)
In the method of Example 1, the food packaging film of Comparative Example 4 was obtained in the same manner as in Example 1 except that the extruder screw rotation speed was changed to 75 rpm. The results are shown in Table 1.
Although the food packaging film obtained in Comparative Example 4 has added an antioxidant, the share deterioration is severe, and the surface area of polypropylene that contributes to the seal strength is reduced, so the seal strength after retort treatment is low and the quality is low. Met. Moreover, blocking resistance was also inferior to the film for food packaging obtained in Example 1.

(Example 2)
In the method of Example 1, Irgafos 168 (Ciba Specialty Chemicals Co., Ltd.) using block copolymerized polypropylene resin (MFR = 3.0 g / 10 min, WFS 5293-22 manufactured by Sumitomo Chemical Co., Ltd.) as a phosphorous antioxidant. Made of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phenolic antioxidant and containing 0.25% by mass of ethylene, 5% xylene soluble part Is a block copolymer polypropylene resin (WFS 5293-26: manufactured by Sumitomo Chemical Co., Ltd., MFR = 3.1 g / 10 min), and the blending ratio is 81 parts by mass, and an ethylene / propylene copolymer resin. Thermoplastic elastomer (MFR = 0.7 g / 10 min, manufactured by Mitsui Chemicals, P0680) Except for changing the total amount to 17 parts by weight, to obtain a food packaging film of Example 2 by the same method as the first embodiment. The results are shown in Table 1.
The food packaging film obtained in Example 2 had the same characteristics as the food packaging film obtained in Example 1 and was of high quality.

(Examples 3, 4, and 5)
In the method of Example 1, the blending amounts of ethylene / propylene copolymer resin-based thermoplastic elastomer (MFR = 0.7 g / 10 min, manufactured by Mitsui Chemicals, P0680) were 7, 9 and 14 parts by mass, respectively. As described above, food packaging films of Examples 3 to 5 were obtained in the same manner as in Example 1 except that the amount of the block copolymerized polypropylene resin was changed so that the total resin amount was 100 parts by mass. The results are shown in Table 1.
The food packaging film obtained in these Examples is excellent in both the fall bag resistance and the sealing strength after the retort treatment in the same manner as the food packaging film obtained in Example 1. there were.

(Example 6)
Ethylene content containing 0.15% by mass of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd., molecular weight 1178) as a phenolic antioxidant and 0.05% by mass of Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.) Is a block copolymer polypropylene resin (MFR = 3.0 g / 10 min, WFS 5293-39 manufactured by Sumitomo Chemical Co., Ltd.) having a mass soluble in xylene at 20 ° C. of 15% by mass, 89.4% by mass, Irganox 1076 Ethylene / propylene copolymer resin-based thermoplastic elastomer (MFR = 0.7 g / 10 min, Mitsui Chemicals, P0680, containing 0.05% by mass of Ciba Specialty Chemicals, Inc., molecular weight 531) ) 10% by mass and 4% by mass ethylene random polypropylene random copolymer resin A masterbatch resin (MA181 manufactured by Sumitomo Chemical Co., Ltd., MFR: 10 g / 10 min) containing 5% by mass of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.), which is a rate-based antioxidant, is 0.6 parts by mass. A food packaging film of Example 6 was obtained in the same manner as in Example 1. The results are shown in Table 1.
The film for food packaging obtained in Example 6 is slightly inferior in sealing strength after retorting treatment than the film for food packaging obtained in Example 1, but has a falling bag breakage resistance and sealing strength after retorting treatment. It was compatible and high quality.

  According to the retort food packaging film of the present invention, it has excellent sealing properties, heat resistance, bag breakage resistance, food hygiene, and simultaneously satisfies the characteristics required as a retort food packaging film suitable for retort processing. . In particular, when used as a component material for packaging bags for retort foods, it has excellent resistance to bag breakage and seal strength after retort treatment, as well as resistance to bag breakage when dropped at low temperatures or when a large external force is applied. In addition to excellent properties suitable for retort processing, the reliability of durability against external forces such as impact of packaging bags during storage and transportation of food after retort processing is improved. Therefore, since it can be used suitably as a constituent material for food packaging films, particularly retort food packaging bags, it greatly contributes to the industry.

Claims (4)

  A film mainly composed of a propylene-ethylene block copolymer, containing at least a phenolic antioxidant, a phosphorous acid antioxidant and an acrylate antioxidant, and having a 20 ° C. xylene soluble part of 15 A film for retort food packaging, characterized in that it is ˜30% by mass, the ratio of broken bag breakage of the film is 20% or less, and the sealing strength after retort treatment is 38 to 110 N / 15 mm.   It consists of a resin composition in which 85 to 97 parts by mass of a block polyolefin resin whose main component is a propylene-ethylene block copolymer having a xylene soluble part of 5 to 20% by mass and 3 to 15 parts by mass of a thermoplastic elastomer. The retort food packaging film according to claim 1.   The retort food packaging film according to claim 1 or 2, wherein the retort food packaging film has a Young's modulus in the lateral direction of 430 to 750 Mpa or more.   The retort food packaging film according to claim 1, wherein the retort food packaging film has a Young's modulus in the transverse direction of 560 to 750 Mpa or more.