JPH08277350A - Sealant film and composite packaging material using the same - Google Patents

Abstract

PURPOSE: To obtain a sealant film capable of withstanding the filling at high temperatures up to 100 deg.C or boiling sterilization in spite of the low-temperature sealability, possessed thereby and equal to that of a convention low-temperature sealed product. CONSTITUTION: This sealant film comprises a resin composition obtained by adding 100-3,000ppm organic amide dimer and 1,000-10,000ppm inorganic filler to a polyethylene-based resin having the melting point within the range of 75-115 deg.C, a value of the weight-average molecular weight/number - average molecular weight within the range of 1.5-3 and the single peak for crystal melting measured by using a differential scanning calorimeter. Thereby, a sealant film capable of preventing slipperiness from deteriorating due to dry lamination processing and improving the operating efficiency and sanitary aspects without requiring operations such as moderation of aging conditions or dusting can be obtained.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a sealant film,
In particular, the present invention relates to a film having heat resistance capable of withstanding high temperature filling up to 100 ° C. and sterilization by boiling, and preventing deterioration in slipperiness due to dry lamination processing, and further relates to a composite packaging material using this film.

[0002]

2. Description of the Related Art In recent years, in the food industry, packaging with a plastic film has been frequently carried out for reasons of hygiene, economy, and ease of handling. Generally, in the food packaging field, the viscosity of a viscous substance to be packaged is reduced, the packaged item is heated to a high temperature before packaging to sterilize the packaged item, and boiled after packaging. There is. As the sealant film for this application, one having a melting point of the resin which is higher than the heating temperature by at least 10 ° C. has been conventionally used so as to prevent deterioration of the seal portion due to heating and fusion between the inner surfaces of the package.

Further, the sealant film is often used by laminating it with a reinforcing layer made of other plastic film or metal foil. However, if laminating is performed during dry laminating, the slipperiness is often deteriorated. Therefore, conventionally, in order to compensate for the reduced slipperiness, measures such as more relaxing the aging condition and shaking powder such as Nikkari powder have been taken (Japanese Patent Publication No. 62-10532).
62-41529).

[0004]

However, in the conventional sealant film, when the sealant film is heated, the sealing surfaces are fused or the seals are fused despite the film melting point being sufficiently higher than the heating temperature (for example, 10 ° C. or higher). However, there was a drawback in that This is because components having a melting point lower than the melting point of the film measured by a differential scanning calorimeter are present in the film, and these are heat-sealed or function as a sealing component.

On the other hand, in order to reduce the manufacturing cost and improve the production efficiency, it is required to speed up the film processing. For this purpose, it is necessary to lower the melting point of the film and lower the sealing temperature. However, if the melting point is lowered, the above-mentioned problems such as fusion occur, so that the film having heat resistance has a sealing temperature of about 2 as compared with the film for low temperature sealing.
It increased by 0 ° C. Therefore, it has been difficult for the conventional sealant film to achieve both low temperature sealing property and heat resistance.

In order to prevent slippage during dry lamination when used as a composite packaging material, it is necessary to take measures such as relaxation of aging conditions and dusting, as described above. In addition to cost,
It was also unfavorable from a hygienic point of view that powder that had melted during sealing adhered to machines and packaged products.

In view of the above points, the first object of the present invention is to
An object of the present invention is to provide a sealant film capable of achieving both low temperature sealability and heat resistance up to 100 ° C.

A second object of the present invention is to prevent deterioration in slipperiness due to dry laminating, to improve work efficiency and hygiene without requiring work such as relaxation of aging conditions and dusting. It is to provide a sealant film capable of

[0009]

The sealant film according to the present invention has been devised to solve the above-mentioned problems.
Melting point is in the range of 75 to 115 ° C., weight average molecular weight /
The number average molecular weight value (hereinafter referred to as M _W / M _N ) is 1.5 to
It is in the range of 3, and the differential scanning calorimeter (hereinafter referred to as DSC)
A polyethylene-based resin having a single crystal melting peak measured by using an organic amide dimer of 100 to 3000 p
pm and an inorganic filler are added in an amount of 1000 to 10000 ppm.

The melting point is in the range of 75 to 115 ° C., and M _W
/ _MN is in the range of 1.5 to 3, and the polyethylene-based resin having a single crystal melting peak measured by DSC is a catalyst having a single polymerization active point (metallocene catalyst, single site). (Known as a catalyst, Kaminsky catalyst, etc.). However, the structure and combination of the catalysts are not particularly limited. The polyethylene resin is used without being mixed with other polyethylene resin.

The reason why the melting point is limited to the range of 75 to 115 ° C. is that the sealant film has low-temperature sealing property and 10
This is to impart heat resistance up to 0 ° C. In particular, 103
Resins having a melting point in the range of ~ 110 ° C are preferred.

M _W / M _N is 1.5 to 3, preferably 1.
It is 8 to 2.6. When M _W / M _N is less than the above lower limit, it becomes very difficult to form a film. On the contrary, when M _W / M _N exceeds the above upper limit, a low molecular weight fusion component is increased, and fusion during heating is likely to occur.

The organic amide dimer acts as a slip agent for preventing a decrease in slipperiness, and the polyethylene resin has 100 to 3000 ppm, preferably 500 to 3000 ppm.
1500 ppm is added. If the addition amount of the organic amide dimer is less than the above lower limit, the effect of preventing slippage deterioration is not sufficiently exhibited, and conversely if it exceeds the above upper limit, the transparency is impaired,
May cause yellowing.

The organic amide dimer used as a slip agent includes ethylenebisoleic acid amide, ethylenebisstearic acid amide, methylbisoleic acid amide,
In addition to methylenebisstearic acid amide, hexamethylenebisoleic acid amide, hexamethylenebisstearic acid amide, etc., there are bisamide slip master batches sold by raw material manufacturers. However, the organic amide dimer that can be used in the present invention is not limited to the above.

The inorganic filler acts as an anti-blocking agent and is added to the polyethylene resin in an amount of 1000 to 1000.
0 ppm, preferably 3500 to 7500 ppm is added. This makes it difficult for the slip agent to migrate during dry lamination and for smoothing the film surface during aging. If the amount of the inorganic filler added is less than the above lower limit, the above-mentioned effects are not sufficiently exhibited, while if it exceeds the above upper limit, the transparency is remarkably impaired and the low temperature sealing property is impaired.

Inorganic fillers used as anti-blocking agents include inorganic salts such as calcium carbonate and magnesium carbonate, natural products such as talc and diatomaceous earth, synthetic silica such as hollow silica and hydrophobic silica, and raw materials. There is an anti-blocking agent masterbatch sold by the manufacturer. However, these inorganic fillers that can be used in the present invention are not limited to the above.

The sealant film according to the present invention has a non-sealing surface, that is, a surface different from the sealing surface, on both surfaces thereof, such as a plastic film, a metal foil, paper, etc. different from the above sealant film, such as a polyamide film. A composite packaging material can be constructed by laminating the reinforcing layers.

[0018]

The sealant film according to the present invention has a DSC
Since there are extremely few components having a melting point lower than the melting point of the film measured, high-temperature filling up to 100 ° C. or boiling sterilization does not cause a decrease in seal strength or fusion between seal surfaces. Therefore, it becomes possible to bring the melting point of the resin close to the heating temperature by a difference of about 4 to 8 ° C., and a polyethylene resin having a low melting point of 75 to 115 ° C. can be used,
It can be appropriately selected according to the heating temperature. A resin having a melting point in the range of 103 to 110 ° C. is particularly preferable for satisfying the low temperature sealing property and imparting heat resistance up to 100 ° C. This is almost the same as the melting point of the conventional low-temperature sealant film. In this way, heat sealing can be performed at a sealing temperature as low as that of the conventional sealant film for low temperature sealing.

As described above, it is possible to provide a sealant film having a low-temperature sealing property comparable to that of conventional low-temperature sealing products, but capable of withstanding high-temperature filling up to 100 ° C. and boiling sterilization.

Further, even if the above film is dry-laminated, the slip property is hardly reduced.

[0021]

【Example】

Example 1 Slip on 100 parts by weight of a polyethylene resin having a density of 0.908 g / cm ³ , a melt index of 1.0 g / 10 min and a melting point of 107 ° C., obtained by polymerization using a catalyst having a single polymerization active point. Agent masterbatch (“Moretech EE-40” manufactured by Idemitsu Petrochemical Co., Ltd.) 3.3 parts by weight (corresponding to 1500 ppm of organic amide dimer), anti-blocking agent masterbatch (“Moretech BB-38” manufactured by Idemitsu Petrochemical Co., Ltd.) 7.5 parts by weight (inorganic filler 750
(Corresponding to 0 ppm) was added, and this mixture was formed into a sealant film having a thickness of 40 μm by an inflation molding machine.

The surface of the obtained film different from the sealing surface was subjected to corona discharge treatment and the wetting tension was set to 40 dyn / c.
Then, a 15 μm thick biaxially oriented polyamide film for reinforcement was attached to the treated surface by dry lamination to obtain a composite packaging material including a sealant film layer and a reinforcement layer.

Example 2 The sealant film obtained in Example 1 was subjected to corona discharge treatment in the same manner as in Example 1. The density of 0.91 obtained by polymerization using a catalyst having a plurality of polymerization active points
0 g / cm ³ , melt index 2.0 g / 10 mi
A polyethylene resin having a melting point of 110 ° C. was formed into a film, and the obtained reinforcing film having a thickness of 15 μm was attached to the corona discharge treated surface in the same manner as in Example 1 to obtain a composite packaging material.

Comparative Example 1 100 parts by weight of a polyethylene resin having a density of 0.910 g / cm ³ , a melt index of 2.0 g / 10 min and a melting point of 110 ° C., obtained by polymerization using a catalyst having a plurality of polymerization active points. , Slip agent masterbatch (Mitsui Petrochemical Co., Ltd. "SQ-3") 1.5 parts by weight (corresponding to erucic acid amide 750 ppm), anti-blocking agent masterbatch (Idemitsu Petrochemical Co., Ltd. "Moretech BB-3"
8 ") 3.0 parts by weight (corresponding to 3000 ppm of inorganic filler) was added, and this mixture was formed into a film in the same manner as in Example 1. A reinforcing film was laminated on the obtained film in the same manner as in Example 1. Thus, a conventional low temperature seal equivalent product was obtained.

Comparative Example 2 Density 0.918 g / c as resin for sealant film
A composite packaging material, which is a conventional heat resistant equivalent product, was obtained in the same manner as in Comparative Example 1 except that a polyethylene resin having m ³ , melt index of 2.1 g / 10 min and melting point of 121 ° C. was used.

The performance of the following four items was examined using the above four types of films. (1) Low temperature sealability The sealability is generally evaluated by a table evaluation using a heat seal bar, but an automatic filling machine was used to obtain more practical data. When the sealing temperature of the film was fixed, the better the low temperature sealing property was, the shorter the sealing time was and the higher the filling rate was. Therefore, the sealing property was expressed by the film length consumed per unit time.

A three-way seal pouch type (vertical 80 mm, horizontal 65 mm) packaging container was prepared from the composite packaging material, and the seal bar temperature was fixed at vertical 175 ° C. and horizontal 185 ° C. "Noodle soup" was used as a filling, and this was filled in a container at room temperature.

The length of the film consumed per unit time was measured in such a range that 100 kg of pressure was applied to the filled container and that the seal portion was not abnormal for 1 minute in this state.

The low temperature sealing property (film consumption length m / min) measured under the above conditions is shown in the graph of FIG.

As is apparent from FIG. 1, the packaging containers using the materials of Examples 1 and 2 have the same low temperature sealability (film consumption length of 20 m / min) as that of Comparative Example 1. .

(2) Heat fusion test As a method of the heat fusion test, the sealing layers were put together in water and fixed with a paper clip to make the sample slightly harsher than the actual boil sterilization. It was left inside for 30 minutes, then rapidly cooled to remove the clip, and the presence or absence of fusion of the adhered portion was judged in three stages.

Criteria were as follows: ◯: no fusion, Δ: fusion was present but could be peeled off by hand, x: strong fusion was present.

As a result of the test under the above conditions, Table 1
As can be seen in Fig. 3, there was no fusion between the packaging containers using the materials of Examples 1 and 2 and Comparative Example 2 having heat resistance, and fusion was observed in that of Comparative Example 1.

(3) High Temperature Filling Test In automatic filling and packaging, in addition to the purpose of sterilization, in order to reduce the viscosity of the viscous substance to be packed, it may be preheated and filled as it is. Therefore, "Noodle soup" was used as the filling material, heated to 95 ° C, and a filling test was performed to confirm the actual heat resistance. The filling speed at this time was 20 m / min, and the sealing temperature was fixed at 175 ° C. vertically and 145 ° C. horizontally. In this test, 100 kg of pressure was applied to the sample immediately after filling and left for 3 minutes. Observe the condition during this period,
The heat resistance of the seal was evaluated in three grades: ◯: no abnormality, Δ: abnormality in the seal part, and ×: bag breakage. The presence or absence of fusion immediately after filling was also determined in the same manner as in (2) Thermal fusion test.

As a result of this test, as shown in Table 2,
In the packaging containers using the materials of Examples 1 and 2, neither fusion nor rupture was observed, but in Comparative Example 1, light fusion was observed. For Comparative Example 2, 20 m
At a speed of / min, filling was not possible due to insufficient low temperature sealability.

(4) Slip Property (Measurement of Friction Coefficient) The slip property of a film is often expressed by a friction coefficient, and its measuring method is specified in ASTM-D1894. Here, according to this standard, the friction coefficient between the seal surfaces before and after the dry lamination of the sealant film and the reinforcing layer was measured. As a result, as shown in Table 3, in the sealant films of Examples 1 and 2, no change was observed before and after lamination, but in Comparative Examples 1 and 2, a slight decrease in slip property (increased friction coefficient) was observed. Was given.

[0037]

[Table 1]

[Table 2]

[Table 3]

[0038]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a sealant film having a low-temperature sealing property comparable to that of a conventional low-temperature sealing product and capable of withstanding high temperature filling up to 100 ° C. and boiling sterilization.

Further, when the sealant film according to the present invention is dry laminated, it is possible to prevent the deterioration of the slipperiness due to this, and it is not necessary to relax the aging conditions or dust the particles, thereby improving the work efficiency and hygiene. You can

[Brief description of drawings]

FIG. 1 is a graph showing a film consumption length per unit time.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08K 5/20 KEW C08K 5/20 KEW // C09J 7/00 JHL C09J 7/00 JHL

Claims (2)

[Claims] 1. The melting point is in the range of 75 to 115 ° C., the weight average molecular weight / number average molecular weight is in the range of 1.5 to 3, and the crystal melting peak measured by using a differential scanning calorimeter is simple. 100 to 3000 ppm of organic amide dimer and 1000 to 1 of inorganic filler in polyethylene resin which is one
A sealant film comprising a resin composition containing 0000 ppm. 2. A composite packaging material in which a reinforcing layer is laminated on the non-sealing surface of both sides of the film according to claim 1.