JPH06322192A - Film for stretch packaging - Google Patents

Abstract

PURPOSE:To obtain the subject film having low-temperature packaging suitability, heat-sealability, self-tackiness, etc., and useful for food packaging, etc., by mixing specific ethylene-(meth)acrylate copolymer resins at a specific ratio and forming the mixture. CONSTITUTION:The objective film is produced by mixing (A) 50-99wt.% of an ethylene-(meth)acrylic acid copolymer resin with (B) 50-1wt.% of an ethylene-(meth)acrylic acid-(meth)acrylic acid ester terpolymer resin and forming the mixture. The mixture may be incorporated with an antifogging agent and a thickener before forming.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a stretch packaging film.

[0002]

2. Description of the Related Art Conventionally, as a so-called stretch wrapping film for pre-packing foods such as fruits and vegetables, fresh fish, meat, prepared foods directly or on a lightweight tray such as plastic, vinyl chloride (PVC) resin, polyolefin ( A multi-layer or single-layer product of PO) type resin is used. Stretch packaging in which layers containing ethylene-vinyl acetate copolymer (EVA) resin with a vinyl acetate content of 5 to 25% by weight are laminated on both sides of a layer containing butene-1 resin as the main component. As a film for use, JP-A-61-89040 and many other resin structures and molding methods have been proposed.

Since the stretch packaging film made of PVC resin has a large temperature dependency, the film may burst during distribution of the package in a low temperature range of -25 ° C or lower. Although the function of the PVC resin is sufficient for the stretch packaging film, it is desired to provide a resin film other than PVC resin in order to cope with recent environmental problems and health and safety problems.

Stretch wrapping films made of multi-layered or single-layered PO resins have a narrow wrapping suitability for various automatic wrapping machines that are used when high-speed processing of wrapping is required or due to lack of packaging experts. Since it is difficult to wrap with commonly used automatic wrapping machines, it is necessary to invest in switching to a wrapping machine exclusively for PO resin. In addition, since it is soft and easy to stretch during packaging, there are drawbacks such as slackening of the film when a package is loaded, and the adhesiveness and heat sealability of the films are deteriorated and the commercial value is lowered. The butene-1-EVA stretch film for packaging proposed in JP-A-61-89040 has the same phenomenon as in the case of the PO resin film.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the problems of the above-mentioned conventional films and to provide a film which fully satisfies all the functions as a stretch packaging film.

[0006]

Means for Solving the Problems The inventors of the present invention have reexamined the raw material resin of a stretch packaging film (hereinafter referred to as a film) in order to solve the above problems, and as a result, two kinds of ethylene- (meth) It has been found that the problem can be solved by mixing an acrylic acid-based resin, and various conditions have been investigated in detail to arrive at the present invention, the gist of which is ethylene- (meth) acrylic acid copolymer resin 50-99 wt. % And ethylene- (meth) acrylic acid- (meth) acrylic acid ester terpolymer resin 50 to 1% by weight as a main component, and if necessary, an antifogging agent and an adhesive agent are added, The film is characterized by being formed.

The present invention will be described in detail below. The greatest feature of the present invention is that two kinds of ethylene- (meth) acrylic acid-based resins are mixed and formed into a film. One of the resins is ethylene- (meth) acrylic acid copolymer resin (hereinafter abbreviated as E (M) AA resin) containing 85 to 97% by weight of ethylene and 3 to 15% by weight of (meth) acrylic acid. Copolymer resins are suitable for the present invention. The other is ethylene- (meth) acrylic acid- (meth) acrylic acid ester terpolymer resin (hereinafter abbreviated as E (M) AAE resin), which contains 3 to 20% by weight of (meth) acrylic acid, ) Ternary copolymers consisting of 3 to 20% by weight of acrylate, balance ethylene, are suitable for the present invention. Here, (meth) acrylic acid represents acrylic acid or (meth) acrylic acid, and (meth) acrylic acid ester represents acrylic acid ester or (meth) acrylic acid ester, and examples thereof include methyl acrylate, ethyl acrylate, and acrylic acid. Examples thereof include isobutyl acid, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, isobutyl methacrylate and the like.

Mixing ratio of these two types of resin (resin component 1
(Breakdown of 00% by weight) is based on E (M) AA resin 50 to 99% by weight.
The (M) AAE resin is preferably mixed in an amount of 50 to 1% by weight, and preferably 60 to 80% by weight of the former and 40 to 20% by weight of the latter.

The film forming method of the present invention may be carried out by a known inflation molding method, and the film can be made to have an appropriate rigidity and mechanical strength such as tear strength in the longitudinal and transverse directions can be obtained. The stress, which is a characteristic required for packaging, when the film is stretched 100% is the longitudinal direction (film flow direction).
Packaging quality range in 110~170kg / cm ^2, by adjusting the range of 60~110kg / cm ² at (the direction perpendicular to the flow direction of the film) laterally in an automatic packaging machine which is commonly used And the suitability for a PO film-only packaging machine is also improved. Further, if it is within the above-mentioned stress range, slack of the film occurs when a package is loaded, and the adhesive strength and heat-sealing property of the films are within the range of the mixing ratio of the resin described above for stretch packaging. To solve the problem by adding an appropriate amount of antifogging agent and pressure sensitive adhesive to the resin for the function to be satisfied and also for the function of the film required for antifogging property, antistatic property, and appropriate slipperiness. You can

The E (M) AAE resin is added to 0 to 49% by weight or 100% by weight of the E (M) AA resin which is outside the applicable range of the present invention.
In the case of 100-51 or 0% by weight mixed resin, the stress at 100% elongation required for packaging is out of the above range in both longitudinal and lateral directions. It becomes difficult, the suitability for an automatic wrapping machine for PO films is extremely narrow, and the slack of the film occurs. With regard to the adhesive strength and heat sealability of the film comrades, there was an excess or deficiency as a function for stretch packaging.

For the purpose of imparting antifogging property, antistatic property, proper slip property, etc., glycerin fatty acid (meth) acrylic acid ester type, sorbitan fatty acid (meth) acrylic acid ester type, polyglycerin fatty acid (meth) acrylic acid type At least one selected from surfactants such as ester-based and ethylene oxide adduct-based surfactants may be added in an amount of 0.5 to 7% by weight, preferably 1 to 5% by weight. If it is less than 0.5% by weight, antifogging property, antistatic property and proper slipperiness cannot be imparted, and if it exceeds 7% by weight, bleeding on the film surface is increased and optical properties such as transparency of the film are remarkable. Get inferior. The thickness of the film of the present invention is preferably 8 to 30 μm. If the thickness is less than 8 μm, the film strength will be insufficient and the film will break during packaging, and if it exceeds 30 μm, the film strength will be excessive and the load on the packaging machine will increase and the packaging cost will increase. It is not preferable.

[0012]

The film of the present invention is excellent in low-temperature characteristics of the resin itself and is formed by the inflation molding method. Therefore, it is possible to obtain appropriate elasticity, tackiness, deformation recovery and sufficient low-temperature packaging suitability necessary for the function of the film. The resin itself has anti-fogging properties, antistatic properties, and proper slip properties, and can be exhibited by imparting it to the resin itself.

[0013]

EXAMPLES The embodiments of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 Ethylene- (meth) acrylic acid copolymer resin (E (M) AA resin) (methacrylic acid content 9% by weight, melt flow rate 10 g / 10 min.) 90% by weight ethylene- (meth) Acrylic acid-isobutyl acrylate terpolymer resin (E (M) AAE resin) (methacrylic acid content 10% by weight, isobutyl acrylate content 10% by weight, melt flow rate
10g / 10min.) 10% by weight of resin was added to 100 parts by weight of a resin, 3 parts by weight of a surfactant was added, and the mixture was kneaded at 170 ° C using an extruder with a diameter of 90 mm and L / D = 28, and a die temperature of 180 ° C. , Blow ratio
Inflation molding at 4.0 gives a thickness of 14μ
m film was produced. Inorganic polypropylene
Meat, fish, and vegetables were placed on trays made of polypropylene, expanded polystyrene, expanded polystyrene, and impact-resistant polystyrene, and stretch-wrapped with the film of the present invention by various stretch automatic packaging machines. The results are shown in Table 1 together with the physical properties of the film. As is clear from Table 1, 1
The stress at 00% elongation fully satisfies the film function, looseness during loading, self-adhesiveness, heat sealability, suitability for automatic packaging machines,
Good results have also been obtained regarding the suitability for automatic packaging machines for PO films.

Example 2 Same as Example 1 except that 30% by weight of E (M) AAE resin (same as in Example 1) was mixed with 70% by weight of E (M) AA resin (same as in Example 1). A film was produced in the same manner and evaluated using this film. As is apparent from Table 1, 100% elongation stress fully satisfies the function of the film, and also regarding slack during loading, self-adhesiveness, heat sealability, suitability for automatic packaging machines, and suitability for PO-only film automatic packaging machines. Good results have been obtained.

(Example 3) Example 1 was repeated except that 40% by weight of E (M) AAE resin (same as in Example 1) was mixed with 60% by weight of E (M) AA resin (same as in Example 1). A film was produced in the same manner as in. The results of evaluation using this film are also shown in Table 1.

Example 4 Example 1 was repeated except that 50% by weight of E (M) AA resin (same as in Example 1) was mixed with 50% by weight of E (M) AA resin (as in Example 1). A film was produced in the same manner as in. The results of evaluation using this film are also shown in Table 1.

Comparative Example 1 A film was produced in the same manner as in Example 1 except that the E (M) AA resin (same as in Example 1) was 100% by weight. As a result of evaluation using this film,
As is clear from Table 1, since the stress at 100% elongation is too high, there are also poor results regarding slack during loading, self-adhesiveness, heat sealability, suitability for automatic packaging machines, and suitability for automatic packaging machines for PO film. Was obtained.

(Comparative Example 2) E (M) AA resin
AN-42162C) 60% by weight of E (M) AAE resin
A film was produced in the same manner as in Example 1 except that 40% by weight of AN-4213C) was mixed. Evaluation was performed using this film. As is clear from Table 1, since the stress at 100% elongation is low, good results were also obtained regarding slack during loading, self-adhesiveness, heat sealability, suitability for automatic packaging machines, and suitability for automatic PO-only film packaging machines. I couldn't do it.

Comparative Example 3 A film was produced in the same manner as in Example 1 except that the E (M) AAE resin (same as in Example 1) was 100% by weight. Evaluation was performed using this film.
As is clear from Table 1, since the stress at 100% elongation is low, good results were also obtained regarding slack during loading, self-adhesiveness, heat sealability, suitability for automatic packaging machines, and suitability for automatic PO-only film packaging machines. I couldn't do it.

(Comparative Example 4) The same evaluation as in Example 1 was carried out using a PVC film. As is apparent from Table 1, the results were good except for the low temperature suitability.

(Physical Property Evaluation Method of Film) (1) BUR (BLOW UP RATIO): Circumference ratio of die circumference and expanded film. (2) Stress at 100% elongation: One film is measured by the test method according to JIS K-6732, and the stress at 100% elongation between marked lines is measured. (3) Looseness during loading: Perform packaging with an automatic packaging machine of Ibaraki Seiki Co., Ltd., put a 30 g ball on the center of the package for 10 seconds, remove it, and measure the time until wrinkles remaining on the film can be removed. To do.
(The shorter the time until wrinkles are removed, the better.) (4) Self-adhesiveness: A fixed load is applied to the end of the film wound into a roll, and the peeled length is measured at a fixed time.
(Peeling distance is either too long or too short.) (5) Heat sealability: Tested by using the "Torient Tester" from Toyo Seiki Co., Ltd. and stacking two films. It is preferable that the test piece is set to a portion and the test is carried out under the condition of holding it at a pressure of 1 kg / cm ² for 1 second, and that the weldability of the overlapped portion is enough to cause a break if peeled off. (6) Applicable width of automatic packaging machine: Use "A-18X" made by Fuji Pack System Co., Ltd. and the machine adjustment width during packaging is 3 stages or more. (7) Suitable width of automatic wrapping machine for PO type film: Using automatic wrapping machine for PO type film, "AW-2600Jr.PE" manufactured by Teraoka Seiko Co., Ltd. The case is good. (8) Low temperature suitability: 30gr against film at -35 ℃
It is okay if the iron ball is dropped from a height of 50 cm and does not break; ○,
If broken, it is defective;

[0021]

[Table 1]

[0022]

INDUSTRIAL APPLICABILITY The film of the present invention is a film excellent in low temperature packaging suitability in addition to having various functions equivalent to those of PVC film, which is the most proven film for stretch packaging at present, and is industrially applicable. The utility value is extremely high.

Claims (1)

[Claims] 1. An ethylene- (meth) acrylic acid copolymer resin
A mixed resin of 50 to 99% by weight and ethylene- (meth) acrylic acid- (meth) acrylic acid ester terpolymer resin 50 to 1% by weight as a main component, and if necessary, an antifogging agent and an adhesive agent. A film for stretch packaging, characterized in that it is formed by adding.