JP6507744B2 - PVC film for food packaging - Google Patents

Description

  The present invention relates to a vinyl chloride-based food packaging film excellent in packaging suitability and dimensional stability.

Stretch films with excellent transparency and flexibility are widely used in food packaging, especially in fresh food packaging for meat, fresh fish, fruits and vegetables, etc. As a film of this type, polyvinyl chloride resin is used. A film made of a polyvinyl chloride resin composition in which an adipic acid ester plasticizer and various antifogging agents are blended is generally used.

In recent years, with the spread of tray packaging, stretch films are widely used in food packaging applications in which trays are overlapped and overlaid under the trays and sealed in a self-adhesive manner. By stretching and using the film in the width direction with a developing machine, packaging by a high stretch automatic packaging machine is rapidly increasing without the need to replace film with different width depending on the tray size.
Therefore, the packaging film is required not only to have properties such as transparency, antifogging properties and mechanical properties, but also to be suitable for high stretch automatic packaging machines. That is, it is necessary that the film can be smoothly unrolled from the film roll, the slipperiness with the tray is good, and the film can be packaged without being broken when stretched. Furthermore, even if time passes, it is required that it is excellent in dimensional stability.

  In order to satisfy such various characteristics, Patent Document 1 discloses 30 to 45 parts by mass of glycerin fatty acid ester and 100 to 10 parts of epoxidized vegetable oil with respect to 100 parts by mass of vinyl chloride resin having a polymerization degree of 1300 to 1450. The stretch film which mix | blended 20 mass parts etc. is disclosed.

  However, although the technology described in Patent Document 1 is excellent in packaging suitability in an automatic packaging machine, a large amount of glycerine fatty acid ester is added as an antifogging agent, so that the dimensional stability of the film roll is inferior and the roll end is extruded. Because the amount is large, it can not be said that the technology is sufficient for practical use. In addition, the reaction force per film width of 350 mm is as large as 200 to 500 gf, and in recent speeding up of the automatic packaging machine, it is required to further reduce the reaction force so that the film can be drawn out more smoothly.

  In addition, the reaction force described here is a load required when unrolling a film from a roll, and when too large, a film can not be unrolled. On the other hand, if the size is too small, the film tends to come off the film carrier in the automatic packaging machine.

  In addition, as a film suitable for a high stretch automatic packaging machine, in Patent Document 2, one kind selected from adipic acid dialkyl ester and adipic acid type polyester having an average molecular weight of 1000 to 3000 per 100 parts by weight of vinyl chloride resin A stretch film comprising 0 to 15 parts by weight of the above, 10 to 30 parts by weight of a triethylene glycol compound having a specific ester group at each of molecular ends, and 10 to 20 parts by weight of an epoxidized vegetable oil is disclosed.

  However, such a film is one in which the triethylene glycol compound used as a plasticizer bleeds out excessively on the film surface and the film is excellent in releasability but is inferior in dimensional stability.

Unexamined-Japanese-Patent No. 2010-100681 WO / 2011/021400

  The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a vinyl chloride-based food packaging film which is excellent in high stretch automatic packaging suitability and dimensional stability.

That is, the gist of the present invention relates to di-linear alkyl adipate (n-C ₆ H ₁₃ , n-C ₈ H ₁₇ , n-C ₁₀ H ₂₁ ) per 100 parts by mass of polyvinyl chloride resin (A). Mixture) 20 parts by mass or more and 35 parts by mass or less of the compound (B), and 5 parts by mass or more and 20 parts by mass or less of the aliphatic dibasic acid ester compound (C) having a weight average molecular weight of less than 1,000 excluding the compound (B) And 5 parts by mass or more and 20 parts by mass or less of the epoxidized vegetable oil (D), and the total of the compounding amounts of (B), (C) and (D) is 35 parts by mass or more and 55 parts by mass or less And the ratio of the compounding mass part of (C) with respect to the compounding mass part of (B) is 0.20 or more and 0.45 or less, It exists in the film for food packaging characterized by the above-mentioned.

  The vinyl chloride-based food packaging film proposed by the present invention is excellent in both the packaging aptitude and the dimensional stability in a high stretch automatic packaging machine, so the film is stretched in the width direction with a horizontal spreader without trouble at high speed and troubles. As it can be done, it makes it possible to make the packaging process more efficient.

  Hereinafter, a food packaging film as an example of the embodiment of the present invention will be described. However, the scope of the present invention is not limited to the embodiments described below.

<Vinyl chloride resin (A)>
As the vinyl chloride resin (A) used in the present invention, a vinyl chloride resin having any average degree of polymerization can be used. Preferably, the average degree of polymerization of the vinyl chloride resin (A) is 1,000 to 1,500. If the average degree of polymerization is 1,000 or more, sufficient mechanical strength can be obtained. On the other hand, when the average degree of polymerization is 1,500 or less, generation of coloring due to decomposition can be eliminated without generating heat with increase in melt viscosity.

  Therefore, from such a point of view, the average degree of polymerization of the vinyl chloride resin (A) is more preferably 1,100 or more, or 1,450 or less in the above range, and among them, 1,200 or more. Or it is further more preferable that it is 1,350 or less.

  As the vinyl chloride resin (A), in addition to homopolymers of vinyl chloride (referred to as "vinyl chloride homopolymer"), copolymers of vinyl chloride and a copolymerizable copolymer (hereinafter referred to as " Listed as “vinyl chloride-based copolymers”, graft copolymers obtained by graft copolymerizing vinyl chloride to polymers other than vinyl chloride-based copolymers (hereinafter, vinyl chloride-based graft copolymers), etc. Can.

  The vinyl chloride homopolymer and the vinyl chloride copolymer can be polymerized by any method such as emulsion polymerization, suspension polymerization, solution polymerization and bulk polymerization.

  In the vinyl chloride-based copolymer, when the content of constituent units other than vinyl chloride in the copolymer is increased, the mechanical properties are decreased, so the ratio of vinyl chloride in the vinyl chloride-based copolymer is 60 to 99. It is preferable that it is mass%.

  The monomer copolymerizable with vinyl chloride may be one having a reactive double bond in the molecule. For example, α-olefins such as ethylene, propylene and butylene, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; unsaturated carboxylic acids such as acrylic acid and methacrylic acid, methyl acrylate And esters of acrylic acid or methacrylic acid such as ethyl methacrylate and phenyl methacrylate, aromatic vinyls such as styrene and α-methylstyrene, vinyl halides such as vinylidene chloride and vinyl fluoride, N-phenylmaleimide, N-substituted maleimides, such as N-cyclohexyl maleimide, etc. can be mentioned, These can be used individually or in combination of 2 or more types.

  As polymers other than a vinyl chloride type copolymer, what is necessary can carry out the graft copolymerization of vinyl chloride should just be it. For example, ethylene / vinyl acetate copolymer, ethylene / vinyl acetate / carbon monoxide copolymer, ethylene / ethyl acrylate copolymer, ethylene / ethyl acrylate / carbon monoxide copolymer, ethylene / methyl methacrylate copolymer, ethylene -A propylene copolymer, an acrylonitrile butadiene copolymer, a polyurethane, a chlorinated polyethylene, a chlorinated polypropylene etc. can be mentioned, These can be used individually or in combination of 2 or more types.

<Adipic acid di-linear alkyl compound (B)>
The film of the present invention can optimize the balance between the dimensional stability of the film and the reaction force by blending adipic acid di straight chain alkyl compound (B).
The linear alkyl of the compound (B) is preferably a mixture of n-C ₆ H ₁₃ , n-C ₈ H ₁₇ and n-C ₁₀ H ₂₁ . The mixing ratio is preferably 40 to 60 mol% of n-C ₆ H ₁₃ , 10 to 30 mol% of n-C ₈ H _{17, and} 20 to 40 mol% of n-C ₁₀ H _21. C ₆ H ₁₃ is 45 to 55 _{mol%, n-C 8 H 17} are 15 to 25 mol%, _n-C 10 _{H 21} is more preferably 25 to 35 mol%.

<Aliphatic dibasic acid ester compound (C)>
The film of the present invention is appropriately bled out on the film surface by blending the aliphatic dibasic acid ester compound (C) having a weight average molecular weight of less than 1,000 excluding the compound (B), and dissolution of the film By reducing the reaction force, excellent packaging suitability can be expressed.

The weight average molecular weight of the compound (C) is suitably less than 1,000, preferably 800 or less, more preferably 500 or less from the viewpoint of bleed out.
Specific examples of the compound (C) include dimethyl adipate (DMA), dibutyl adipate (DBA), diisobutyl adipate (DIBA), di-2-ethylhexyl adipate (DOA), diisononyl adipate (DINA), adipine Examples include diisodecyl acid (DIDA), di-2-ethylhexyl azelate (DOZ), dimethyl sebacate (DMS), dibutyl sebacate (DBS), di-2-ethylhexyl sebacate (DOS) and the like.

<Epoxidized vegetable oil (D)>
By blending the epoxidized vegetable oil (D), the film of the present invention can improve the softening and thermal stability of the polyvinyl chloride resin (A) without causing excessive bleed-out.
Specific examples of the epoxidized vegetable oil (D) include, for example, epoxidized soybean oil, epoxidized linseed oil, epoxidized cottonseed oil, epoxidized peanut oil, epoxidized safflower oil, epoxidized grape seed oil, epoxidized olive oil etc. These can be used alone or as a mixture of two or more. Among them, epoxidized soybean oil and epoxidized linseed oil are particularly preferably used from the viewpoint of compatibility with the vinyl chloride resin.

<Blending ratio of each component>
The compounding ratio of each component used in the present invention is preferably 20 parts by mass or more and 35 parts by mass or less of the compound (B) with respect to 100 parts by mass of the polyvinyl chloride resin (A), The lower limit is more preferably 22 parts by mass or more, further preferably 25 parts by mass or more. On the other hand, the upper limit is more preferably 33 parts by mass or less, still more preferably 30 parts by mass or less. By blending the compound (B) within such a range, it is possible to optimize the balance between the dimensional stability of the wrap film and the reaction force.

  The compound (C) is preferably compounded in a proportion of 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polyvinyl chloride resin (A). The lower limit is more preferably 7 parts by mass or more, and still more preferably 9 parts by mass or more. On the other hand, the upper limit is more preferably 17 parts by mass or less, and still more preferably 15 parts by mass or less. By blending the compound (C) in such a range, it is possible to bleed out appropriately on the film surface, and to develop excellent packaging suitability by reducing the reaction force of the film.

  Moreover, as a compounding quantity of epoxidized vegetable oil (D), it is preferable to mix | blend in the ratio of 5 mass parts or more and 20 mass parts or less with respect to 100 mass parts of vinyl chloride resin (A), and a minimum is 7 mass parts The content is more preferably 10 parts by mass or more. On the other hand, the upper limit is more preferably 18 parts by mass or less, and still more preferably 15 parts by mass or less. By blending the epoxidized vegetable oil (D) in such a range, it is possible to improve the flexibility and thermal stability of the polyvinyl chloride resin (A) without causing excessive bleed out.

  In addition, it is important that the total of the blending amounts of (B), (C) and (D) is 35 parts by mass or more and 55 parts by mass or less with respect to 100 parts by mass of the vinyl chloride resin (A), and the lower limit Is more preferably 37 parts by mass or more, and still more preferably 40 parts by mass or more. On the other hand, the upper limit is more preferably 53 parts by mass or less, and still more preferably 50 parts by mass or less. By setting the total of the compounding amounts of (B), (C) and (D) in the above range, a food packaging film excellent in both packaging suitability and dimensional stability can be provided.

Furthermore, the ratio of the blending mass part of (C) to the blending mass part of (B) shown in the following formula (1) (blending mass part of compound (C)) / (blending mass part of compound (B)) 1)
It is important that is 0.20 or more and 0.45 or less. The lower limit is more preferably 0.23, and even more preferably 0.25. On the other hand, the upper limit is more preferably 0.43 and even more preferably 0.40.
Since the compound (B) can not be sufficiently exposed on the film surface when the value of the formula (1) is 0.20 or less, that is, the compounding amount of the compound (C) is too small relative to the compound (B), In some cases, sufficient reaction force can not be obtained. On the other hand, when the value of the formula (1) is at least 0.45, that is, the compounding amount of the compound (C) is too large relative to the compound (B), the bleed out of the compound (C) to the film surface becomes excessive. The dimensional stability of the film may be impaired.

<Other ingredients>
<Heat stabilizer>
In the film of the present invention, in order to improve the thermal stability in the production process, it is preferable to incorporate a heat stabilizer. Among them, a Ca-Zn-based stabilizer is preferable from the viewpoint of not containing harmful heavy metals. The Ca-Zn stabilizer is a mixture of a fatty acid salt of calcium and a fatty acid salt of zinc. Specific examples of the fatty acid include behenic acid, stearic acid, lauric acid, oleic acid, palmitic acid, ricinoleic acid, benzoic acid and the like, and two or more kinds can be used in combination depending on the purpose.
In addition, the weight ratio of calcium to zinc is preferably 1: 1 to 1: 5, more preferably 1: 1.5 to 1: 4, and still more preferably 1: 2 to 1: 3. If the ratio of zinc to calcium is less than 1, the redness peculiar to calcium salts will be produced, while if the ratio of zinc to calcium is more than 5, zinc chloride formed during molding is a vinyl chloride resin It becomes a catalyzing catalyst, causing rapid blackening and decomposition called "zinc burn".

  The addition amount of the Ca-Zn stabilizer is preferably 0.1 parts by mass or more and 2.0 parts by mass or less, and 0.3 parts by mass or more with respect to 100 parts by mass of the vinyl chloride resin (A). 1.8 parts by mass or less is more preferable. If it is less than 0.1 part by mass, the effect of imparting thermal stability may not be sufficient, while if it exceeds 2.0 parts by mass, it may cause rapid blackening and decomposition called "zinc burn". .

<Anti-fog agent>
Moreover, it is preferable to add the ester compound of a polyhydric alcohol and a fatty acid to the film of this invention, in order to provide anti-fogging property. For example, monoglycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester and polyoxyethylene alkyl ether can be mentioned, and they may be used alone or in combination of two or more.

  The monoglycerin fatty acid ester is preferably a monoglycerin ester of a saturated or unsaturated fatty acid having 12 to 18 carbon atoms. Specifically, monoglycerin laurate, monoglycerin myristate, monoglycerin palmitate, monoglycerin stearate, monoglycerin oleate, monoglycerin linoleate and the like can be mentioned.

  The polyglycerin fatty acid ester is preferably a polyglycerin ester of a saturated or unsaturated fatty acid having 12 to 18 carbon atoms. Specifically, polyglycerin laurate, polyglycerin myristate, polyglycerin palmitate, polyglycerin stearate, polyglycerin oleate, polyglycerin linoleate and the like can be mentioned.

  As sorbitan fatty acid ester, sorbitan ester of a saturated or unsaturated fatty acid having 12 to 18 carbon atoms is preferable. Specific examples include sorbitan laurate, sorbitan myristate, sorbitan palmitate, sorbitan stearate, sorbitan oleate, sorbitan linoleate and the like.

  The polyoxyethylene alkyl ether is preferably a polyoxyethylene alkyl ether of a saturated alcohol having 12 to 18 carbon atoms, more preferably a polyoxyethylene alkyl ether in which the number of moles of ethylene oxide added is 3 to 7. Specifically, polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene palmityl ether, polyoxyethylene stearyl ether and the like can be mentioned.

The addition amount of the ester compound of polyhydric alcohol and fatty acid is preferably 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the polyvinyl chloride resin (A) It is more preferable that it is mass part or more and 4.5 mass parts or less, and it is more preferable that it is 1.0 mass part or more and 3.5 mass parts or less.
If the addition amount of the ester compound is 0.1 parts by mass or more, sufficient antifogging properties can be exhibited, for example, when the food container etc. is packaged and stored, water droplets are generated in the film, and confirmation of the contents You can eliminate the problem that you can not On the other hand, if it is 5.0 parts by mass or less, excessive bleed out of the ester compound of polyhydric alcohol and fatty acid to the film surface can be suppressed, and the packaging suitability can be satisfied.

<Other additives>
Furthermore, to the present resin composition, the addition of an antioxidant, an ultraviolet light absorber, a light stabilizer, an antibacterial / antifungal agent, an antistatic agent, a lubricant, a pigment, a dye and the like to the extent that the effects of the present invention are not impaired. Agents can be formulated.

<Manufacturing method>
A known method can be used for the method of producing a film of the present invention. For example, polyvinyl chloride resin (A), di-linear alkyl adipate (mixture of n-C6, 8, 10) compound (B), aliphatic dibasic having a molecular weight of less than 1,000 excluding the compound (B) Acid ester compound (C), epoxidized vegetable oil (D) and other additives are mixed by a mixer such as a V-type blender, ribbon blender or Henschel mixer, an extruder, mixing roll, Banbury mixer, kneader A film can be produced by, for example, a T-die method, an inflation method, or the like after a method of kneading it with a kneader or a combination of a mixer and a kneader and mixing and kneading it.

  The thickness of the film of the present invention is 5 μm or more and 20 μm or less, more preferably 8 μm or more and 18 μm or less, and still more preferably 10 μm or more and 15 μm or less. If it is less than 5 μm, the strength may be broken when packaging protruding shapes such as cucumbers and crabs, and if it exceeds 20 μm, the film is hardly stretched and the packaging suitability is deteriorated.

<Reaction force>
The reaction force of the film of the present invention is preferably 80 gf or more and 190 gf or less per 350 mm of film width. The lower limit of the reaction force is more preferably 90 gf or more, and still more preferably 100 gf or more. On the other hand, the upper limit is more preferably 180 gf or less, and still more preferably 170 gf or less. Within the range where the reaction force is applied, when packaging food or the like with an automatic packaging machine, the unwinding property of the film is good, and the productivity is excellent.

The reaction force of the film can be measured by the following method (hereinafter, abbreviated as reaction force measurement method).
First, the core rod is passed horizontally through the roll winding tube so that the roll can freely rotate, the film end is pulled up vertically above the roll, fixed and carried uniformly over the entire film width, and set. The roll is then lowered vertically downward and the force at which the film uncoils from the roll is measured.
In the present invention, a film roll having a width of 350 mm is set, and using a strograph type or an autograph type tensile tester, the strength change of the unfolding force during lowering the distance of 500 mm at a speed of 500 mm / min. It measured and the value when the force became strong, ie, the average value of the value of each vertex on a measurement graph, was made into the reaction force.

  Although an example is shown below, the present invention is not restricted at all by these. In addition, the various measured values and evaluation about the raw material and test piece displayed in this specification were performed as follows.

<Evaluation method>
(1) Packaging suitability 8 Shishamo 8 tails were put on a tray made of polypropylene, packaged with Ishida's Wmini-UNI machine at an ambient temperature of 23 ° C., packaging speed of 35 packs / min, and packaging suitability was judged based on the following criteria. .
○: no wrinkles and tears, and packaging was possible ×: wrinkles, tears and insufficient tension occurred

(2) Dimensional stability (stick out)
Measure the dimensional change in the film width direction after storing a film roll of 350 mm wide and 1000 m long wound around a paper tube in a constant temperature and humidity chamber with an ambient temperature of 40 ° C and a relative humidity of 60% for 10 days. And was judged on the basis of the following criteria.
○: no change or less than 10 mm ×: greater than 10 mm

(3) Resolving force Using a solution force measurement method, a film roll of width 350 mm is set, and using an autograph tensile tester, the force to be resolved while lowering the distance of 500 mm at a speed of 500 mm / min. The change in strength was measured, and the value when the force became strong, that is, the average value of the values of each vertex on the measurement graph was calculated.

<Material used>
[Vinyl chloride resin (A)]
(A) -1: vinyl chloride homopolymer, average polymerization degree 1300

[Adipic acid di-linear alkyl compound (B)]
(B) -1: Mixed molar ratio of di-linear alkyl adipate and alkyl nC ₆ H ₁₃ : n C ₈ H ₁₇ : n C ₁₀ H ₂₁ = 48: 23: 29

[Aliphatic dibasic acid ester compound (C) having a molecular weight of less than 1,000]
(C) -1: Diisononyl adipate, molecular weight: 398

[Epoxidized vegetable oil (D)]
(D) -1: epoxidized soybean oil

[Stabilizer (E)]
(E) -1: mixture of fatty acid Ca salt and fatty acid Zn salt, Ca: Zn mass ratio = 1: 2

Example 1
100 parts by mass of (A) -1, 30 parts by mass of (B) -1, 10 parts by mass of (C) -1, 10 parts by mass of (D) -1, 1 part by mass of (E) -1 After being charged into the super mixer in proportion, the material temperature was raised from normal temperature to 130 ° C. with stirring, and after heating and mixing, it was taken out when cooled to 70 ° C. to obtain a resin composition.
The obtained resin composition was extrusion molded at a resin temperature of 200 ° C. in a 4040 mm single screw extruder (L / D = 20) equipped with a T-die (width 350 mm, gap 0.4 mm) to a thickness of 0. A film of 01 mm was obtained.
The obtained film was evaluated for packaging suitability, dimensional stability, and reaction force. The results are shown in Table 1.

(Example 2)
A film was prepared and evaluated in the same manner as in Example 1 except that the proportion of (C) -1 was changed to 7 parts by mass in Example 1. The results are shown in Table 1.

(Example 3)
A film was produced and evaluated in the same manner as in Example 1 except that the proportion of (B) -1 was 28 parts by mass and the proportion of (C) -1 was 12 parts by mass in Example 1. The results are shown in Table 1.

( Reference Example 1 )
A film was prepared and evaluated in the same manner as in Example 1 except that the ratio of (B) -1 was 23 parts by mass and the ratio of (D) -1 was 15 parts by mass in Example 1. The results are shown in Table 1.

(Comparative example 1)
A film was prepared and evaluated in the same manner as in Example 1 except that the proportion of (B) -1 was 35 parts by mass and the proportion of (C) -1 was 3 parts by mass in Example 1. The results are shown in Table 1.

(Comparative example 2)
A film was prepared and evaluated in the same manner as in Example 1 except that the proportion of (B) -1 was 15 parts by mass and the proportion of (C) -1 was 25 parts by mass in Example 1. The results are shown in Table 1.

From Table 1, Examples 1 to 4 had good automatic high-speed packaging properties and dimensional stability because a specific composition was adopted for the vinyl chloride resin (A).
On the other hand, in Comparative Example 1, the blending mass part of the compound (C) to the compound (B) was small, and the film required a force to unroll, lacked stability at the film unrolling from a roll, and trouble occurred at packaging. . In Comparative Example 2, the compounding amount of the compound (C) was large, and the dimensional stability was poor.

  The film of the present invention is excellent in film unwinding characteristics suitable for high-speed automatic packaging, width-oriented film stretching characteristics suitable for high-stretch automatic packaging machines, and dimensional stability during roll storage, so that the efficiency of the food packaging process Greatly contribute to

Claims (4)

Di-linear alkyl adipate (a mixture of n-C ₆ H ₁₃ , n-C ₈ H ₁₇ , n-C ₁₀ H ₂₁ ) compound (B) per 100 parts by mass of polyvinyl chloride resin (A) 5 parts by mass or more and 35 parts by mass or less, and 5 parts by mass or more and 20 parts by mass or less of aliphatic dibasic acid ester compounds (C) having a weight average molecular weight of less than 1,000 excluding compound (B), epoxidized vegetable oil (D) Of 5 parts by mass or more and 20 parts by mass or less, and the total of the compounding amounts of (B), (C) and (D) is 35 parts by mass or more and 55 parts by mass or less, and the composition of (B) A film for food packaging, wherein the ratio of the blending mass part of (C) to the mass part is 0.20 or more and 0.45 or less. The proportion of linear alkyl in the compound (B) is 40 to 60 mol% of nC ₆ H _13, 10 to 30 mol% of nC ₈ H _{17, and} 20 to 40 mol of nC ₁₀ H ₂₁ The film for food packaging according to claim 1, which is%.   The film for food packaging according to claim 1 or 2, wherein the reaction force is 80 gf or more and 190 gf or less per 350 mm of film width.   The film for food packaging according to any one of claims 1 to 3, wherein the compound (C) is diisononyl adipate.