JPH04202437A - Film for packaging fruit and vegetable - Google Patents

Abstract

PURPOSE:To provide the title film which is excellent in gas permeability and mechanical strengths, protects fruit and vegetable from being soiled or damaged when used for packaging them, and keeps them fresh by selecting a poly(4- methyl-1-penetene) film. CONSTITUTION:The title film mainly comprises a polymer consisting of 100-80 pts.wt. 4-methyl-1-penetene and 0-20 pts.wt. other alpha-olefin, pref. 1-hexadecene or 1-octadecene. A pref. wt. ratio of 4-methyl-1-pentene to the alpha-olefin in the polymer is (85:15)-(98:2) to obtain excellent gas permeability and high mechanical strengths.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a film for packaging fruits and vegetables, and in particular, it has excellent gas permeability and mechanical strength, and is suitable for packaging fruits and vegetables.
This invention relates to a fruit and vegetable packaging film that can protect against staining and damage and maintain its freshness well.

<Prior Art> Conventionally, fruits and vegetables, such as vegetables and fruits, have been wrapped in packaging films in order to protect them from staining and the like and maintain their freshness. For example, vegetables such as lettuce, green peppers, broccoli, spinach, and shiitake mushrooms, and fruits such as peaches are wrapped in packaging films made of polypropylene, low-density polyethylene, polybutadiene, etc. to protect them from staining and damage and to maintain their freshness. It is being held.

<Problems to be Solved by the Invention> However, films made of polypropylene or low-density polyethylene have poor permeability to gases such as carbon dioxide gas, oxygen gas, and water vapor, making it difficult to maintain the freshness of vegetables that breathe a lot during summer. There were problems such as not being able to retain the vegetables sufficiently and reducing the commercial value of these vegetables.

Furthermore, although a film made of polybutadiene has good gas permeability, it is opaque, so the packaged items cannot be seen from the outside, and there are also problems in that the film is inferior in mechanical strength.

Therefore, the purpose of the present invention is to package fruits and vegetables with excellent gas permeability and mechanical strength to protect them from staining and damage.
It is an object of the present invention to provide a film for packaging fruits and vegetables that can maintain freshness well.

Means for Solving the Problems> In order to solve the problems, the present invention provides 4-methyl-1
- 100 to 80 parts by weight of pentene and 4 having 2 to 24 carbon atoms
-α-olefin other than methyl-1-pentene 0 to 20
The present invention provides a film for packaging fruits and vegetables, the main component of which is a polymer (I) consisting of parts by weight.

Hereinafter, the fruit and vegetable packaging film of the present invention will be explained in detail.

Polymer (
1) is a homopolymer of 4-methyl-1-pentene, or 4-methyl-1-pentene and a 4-carbon polymer having 2 to 24 carbon atoms.
-Copolymers with α-olefins other than methyl-1-pentene may be mentioned. 4-methyl-1 having 2 to 24 carbon atoms
- Examples of α-olefins other than pentene (hereinafter abbreviated as “α-olefins”) include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1
-decene, 1-tetradecene, 1-octadecene, 1-
Examples include hexadecene, 1-dodecene, 1-tetradodecene, and the like. One or more of these α-olefins may be contained in the polymer (I). Among these α-olefins, 1-hexadecene and 1-octadecene are preferred.

In polymer (I), 4-methyl-1-pentene and α
- The content ratio of olefin is 0 to 100 to 80 parts by weight of 4-methyl-1-pentene and 0 parts by weight of α-olefin in order to exhibit excellent performance in gas permeability and mechanical strength.
~20 parts by weight, preferably 4-methyl-1-pentene8
The ratio is 2 to 15 parts by weight of α-olefin to 5 to 98 parts by weight.

This polymer (I) can be produced according to a known method and is not particularly limited.

For example, stereoregular polymerization using a Ziegler-Natsuta catalyst, cationic polymerization, or the like can be used.

Moreover, this polymer (I) may be graft-modified with a modified polymer. When the polymer (I) is graft-modified, it is preferable in that a film for packaging fruits and vegetables with excellent adhesiveness and sealing properties can be obtained.

Examples of the modified polymer include (meth)acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid (endocys-bicyclo[2,2,11 unsaturated carboxylic acids such as hebut-5-dyne-2,3-dicarphonic acid) or their conductors, such as acid halides,
Examples include acid amides, acid imides, acid anhydrides, esters, etc. Specific examples include maleyl chloride, maleimide, maleic anhydride, citraconic anhydride, dimethyl maleate, glycidyl maleate, methyl (meth)acrylate, (meth) ) (meth)acrylic acid alkyl esters such as ethyl acrylate. These may be single-class vehicles or two or more types may be included. Among these, unsaturated dicarboxylic acids or their acid anhydrides are preferred, and maleic acid, nadic acid, or their acid anhydrides are particularly preferred.

When the polymer (1) is graft-modified, the content of the stiff modified polymer in the polymer (1), that is, the amount of grafting, is usually about 0.05 to 20% by weight. , preferably about 0.1 to 5% by weight.

The production of the polymer (1) graft-modified with the modified monomer is carried out by mixing the polymer (I) and the modified monomer in a solvent in the presence of a polymerization initiator, usually at The reaction can be carried out according to a method of reacting at a temperature of about 300°C, preferably about 125 to 250°C.

Examples of the polymerization initiator used include di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-
Alkyl peroxides such as butyl peroxy-hexyne-3 and diisopropyl peroxide; aryl peroxides such as dicumyl peroxide; acyl peroxides such as lauroyl peroxide; aroyl peroxides such as dibenzoyl peroxide; Ketone peroxides such as methyl ethyl ketone hydroperoxide and cyclohexanone peroxide, t-butyl peroxide,
Hydroperoxides such as cumene hydroperoxide;
and organic peroxides such as peroxycarbonates and peroxycarboxylates. These may be used alone or in combination of two or more. The amount of the polymerization initiator used is usually about 0.01 to 1 part per 100 parts of the polymer (I).

In addition, when a solvent is used, examples of the solvent include hexane, heptane, octane, decane, dodecane,
Aliphatic hydrocarbons such as tetradecane; alicyclic hydrocarbons such as methylcyclopentane, cyclohexane, methylcyclohexane, cyclooctane, cyclododecane; benzene, toluene, xylene, ethylbenzene, cumene, ethyltoluene, trimethylbenzene, cymene, diisopropylbenzene Aromatic IF group hydrocarbons such as; chlorobenzene,
Bromobenzene, 0-dichlorobenzene, carbon tetrachloride,
Examples include halogenated hydrocarbons such as trichloroethane, trichloroethylene, tetrachloroethane, and tetrachloroethylene; or kerosene, which is a mixture of aliphatic hydrocarbons. These may be used alone or in combination of two or more. The proportion of this solvent used is usually about 100 to 5000 parts by weight per 100 parts by weight of polymer (I).

Graft modification can also be carried out by melt-kneading using an extruder, and in this case, the graft modification reaction can be carried out at 235 to 250° C. without using a solvent.

Moreover, the fruit and vegetable packaging film of the present invention is made of the polymer (
1) as the main component, but in addition to this polymer (I), it may contain another polymer (II). The fruit and vegetable packaging film of the present invention is made from this polymer (II).
When it contains, it is preferable in terms of improvement in film strength, sealability, and moldability.

Other polymers (II) include, for example, low density polyethylene (LDPE), linear low density polyethylene (L
LDPE), polypropylene (pp), polystyrene (
ps), polyvinyl chloride (pvc), polyvinylidene chloride (PVDC), polymethyl methacrylate (PMMA)
, polymethacrylic acid (PMA), ethylene/propylene rubber, ethylene/butene copolymer (EB rubber), styrene/butadiene rubber (SBR), polybutadiene, and the like. Also included are blends of the polymer (I) and the graft modified product.

When the fruit and vegetable packaging film of the present invention contains this polymer (11), its content is usually about 0.5 to 50%, preferably about 1.0 to 30%.

In addition, the fruit and vegetable packaging film of the present invention conversely uses polypropylene, polybutadiene, and low density polyethylene (LDP).
E) For the purpose of imparting gas permeability to linear low-density polyethylene (LLDPE), etc., the above polymer (I )
A blend of 0.5 to 50%, preferably 1.0 to 30% of , Polybutadiene or other polymers may be radiation-grafted with 4-methyl-1-pentene to impart gas permeability, or polypropylene, low-density polyethylene (LDPE), or Density polyethylene (LL
DPE), polybutadiene, etc. to which an epoxy compound is added (A), and poly(4-methyl-1-pentene) grafted with maleic anhydride, etc. (B) may be polymerized to form a raw material. .

Moreover, the fruit and vegetable packaging film of the present invention is made of the polymer (
In addition to polymer (I) or polymer (II), the film may contain, if necessary, various additives that are usually incorporated into this type of film within a range that does not impair the object of the present invention.
Examples of such additives include pigments, antifogging agents, slip agents, and antiblocking agents.

The fruit and vegetable packaging film of the present invention can be produced by a conventional method and is not particularly limited. For example, the polymer (r) or polymer (11) and various additives as necessary are mixed in advance or supplied to an extruder without being mixed, and heated to about 240 to 280°C. Examples include a T-die method in which the mixture is melted and kneaded and extruded through a T-die having a predetermined lip gap to form a film; and a blown film molding method.

The thickness of the fruit and vegetable packaging film of the present invention is appropriately selected depending on the fruits and vegetables to be packaged, but is usually about 10 to 30. Preferably, the thickness is about 20 μs.

The gas permeability of the fruit and vegetable packaging film of the present invention was measured using a film with a thickness of 50 units, and the permeation amount of carbon dioxide was 1.
, 2 x 105IIll/nn2-24hr-
4.0XIO'm/rn2 permeation amount of oxygen about at diameter
- Approximately 24hr-atm, and moisture permeability is 653
It is about 7m2/24hr/atm. Incidentally, polypropylene with a thickness of 50 mm has a carbon dioxide permeation rate of 6
, 5 X 10' mfl 7m2・24hr-a
tm, oxygen permeation amount is 1.6 x 103mj
It is about 2/+n2・24hr・atm, and the moisture permeability is 7
It is about 37m2・24hr-at+n.

<Example> Hereinafter, the present invention will be specifically explained by giving examples and comparative examples of the present invention.

(Example 1) A co-M combination of 4-methyl-1-pentene and hexadecene (4-methyl-1-pentene/hexadecene weight ratio +9515) was supplied to an extruder and heated and melted at 280°C. It is then kneaded and extruded from a T-die to a thickness of 20 mm.
Obtained transparent film of voice.

The obtained film was formed into a bag using a side sealing machine.

The fruits and vegetables listed in Table 1 were placed in this bag, sealed, and subjected to a storage test under the following conditions to determine how long they could maintain freshness. The results are shown in Table 1.

Lettuce Stored at 29-32°C Peaches, 6 days at 29-32°C, then 4 days at 9°C Bean sprouts: Stored at 9°C Broccoli: Stored at 9°C (Example 2) 4-Methyl-1-pentene and hexadecene A film was obtained in the same manner as in Example 1, except that a mixture of this copolymer and 3% by weight of low density polyethylene was used instead of the copolymer. It was subjected to a storage test. The results are shown in Table 1.

(Example 3) Example 1 except that instead of the copolymer of 4-methyl-1-pentene and hexadecene, a mixture of this copolymer and 10% by weight of ethylene-propylene copolymer was used. Obtain a film in the same manner as above, and then make a bag,
It was used in a fruit and vegetable preservation test. The results are shown in Table 1.

(Example 4) Example 1 except that instead of the copolymer of 4-methyl-1-pentene and hexadecene, a mixture of this copolymer and 7% by weight of ethylene-butene copolymer was used. A film was obtained in the same manner as above, and a bag was made and used for a fruit and vegetable preservation test. The results are shown in Table 1.

(Example 5) In the same manner as in Example 1, except that instead of the copolymer of 4-methyl-1-pentene and hexadecene, a mixture of this copolymer and 5% by weight of polypropylene was used.
A film was obtained, a bag was made, and the bag was used for a fruit and vegetable preservation test. The results are shown in Table 1.

(Example 6) The same procedure as in Example 1 was carried out, except that instead of the copolymer of 4-methyl-1-pentene and hexadecene, a mixture of this copolymer and 6% by weight of polybutadiene was used. ,
A film was obtained, a bag was made, and the bag was used for a fruit and vegetable preservation test. The results are shown in Table 1.

(Comparative Example 1) A film was obtained in the same manner as in Example 1, except that polypropylene was used instead of the copolymer of 4-methyl-1-pentene and hexadecene. It was subjected to a storage test. The results are shown in Table 1.

(Comparative Example 2) A film was obtained in the same manner as in Example 1, except that low-density polyethylene was used instead of the copolymer of 4-methyl-1-pentene and hexadecene, and a bag was also made. ,
A preservation test was conducted on fruits and vegetables. The results are shown in Table 1.

<Effects of the Invention> The fruit and vegetable packaging film of the present invention has excellent gas permeability and mechanical strength, so it is suitable for packaging fruits and vegetables, and in particular, it has excellent gas permeability even when packaging vegetables etc. that have a large amount of respiration. Therefore, it is effective in preserving the freshness of these vegetables.

Claims (1)

[Claims] The main component is a polymer (I) consisting of 100 to 80 parts by weight of 4-methyl-1-pentene and 0 to 20 parts by weight of an α-olefin other than 4-methyl-1-pentene having 2 to 24 carbon atoms. Film for packaging fruits and vegetables.