KR920003036B1 - Heat adhesive composition and multi layered film using it - Google Patents

Abstract

(A) 10-50 wt.% of polyethylene grafted with 0.1-20 wt.% of maleic anhydride as functional gp.; (B) 50-90 wt.% of low density polyethylene of 0.1-5 of melt index at 190 deg.C and 0.917-0.927 of density. The melt index of the obtd. compsn. is 0.1-5 at 190 deg.C. The obtd. heat- sensitive resin is laminated on outest layer with other resin film eg. pref. polyamide, polycarbonat, polypropylene or polyethyleneterephthalate. The obtd. resin compsn. has a good adhesive intensity and broad heat adhesion temp.

Description

Thermal adhesive resin composition and multilayer film using the same

The present invention relates to a heat-adhesive resin composition and a multilayer film produced using the resin composition. More specifically, a resin composition composed of polyethylene containing maleic anhydride and low density polyethylene, and the resin composition is applied to a resin film such as polyamide to have excellent adhesive strength and a wide thermal bonding temperature range. It relates to a multilayer film that can be used for various substrates such as films.

In general, so-called flexible package films used for packaging films, particularly for packaging food, medical devices, etc. have at least one adhesive polyolefin resin layer for adhesion to other materials, the coating of this resin layer According to the method, it is divided into extrusion coating method and coextrusion coating method.

It is no exaggeration to say that in a soft packaging film, the adhesive strength, the adhesive temperature range, the adhesion time, and the speed of the packaging machine depend on the properties of the adhesive resin layer. Examples of commonly used resin layers for adhesion include low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene vinyl acetate copolymer, and the like.

For example, US Pat. Nos. 3,707,393 and 3,789,035, 3,496,061, 4,189,519, and the like. U.S. Patent No. 3,707,393 is based on the composition of ionomers and terpolymers and simply employs a method of physical mixing.

In addition, US Pat. No. 3,789,035 relates to a method for neutralizing carboxyl groups of different polymers by contact with neutralized carboxyl groups in the polymer, and US Pat. No. 3,496,061 relates to a heat-adhesive resin composition using two different materials. Peel strength is more than 400g / inch. And 4,189,519 is characterized in that one component of the thermoplastic resin composition is isotactic polybutylene.

However, the above-mentioned inventions have various problems, that is, the extrusion coating method generally has excellent flow characteristics and wettability while problems such as film instability, blocking, and thickness irregularity occur. Difficulties arise when producing extrusion castings or inflation films. In particular, when co-extrusion with a high heat-resistant resin such as polyamide, polycarbonate, etc., the blocking and film formation instability between the films is more serious due to the low vicat softening point and viscosity decrease at high temperature. In other words, it is difficult to manufacture inflation films and use coextrusion methods.

Accordingly, the present invention has been made in an effort to provide a resin composition and a multilayer film prepared from the resin composition, which solve problems such as blocking between films and film formation instability, thereby maintaining excellent adhesive strength with a substrate and imparting high temperature processing stability during film production. Put it.

Hereinafter will be described in detail the contents of the present invention.

The present invention (A) 10 to 50% by weight of polyethylene graft (B) melt index is 0.1 to 5, at 190 ° C graft reaction by adding 0.1 to 20% by weight of maleic anhydride (A) functional group It relates to a heat-adhesive resin composition composed of 50 to 90% by weight of low density polyethylene having a density of 0.917 to 0.927, and a multilayer film having the resin composition as a heat-adhesive layer or an outermost layer.

In this case, the graft reaction polyethylene may be low density polyethylene, linear low density polyethylene, or high density polyethylene.

The multilayer film is composed of at least two different resin layers, one layer of which is one of polyamide, polycarbonate, polypropylene, and polyethylene terephthalate.

As a manufacturing method of this film, it is possible to use the normal T-Die coextrusion film manufacturing apparatus or the coextrusion inflation film manufacturing apparatus.

The thermal adhesive strength of the multilayer film of the present invention manufactured by such a method can be measured by a standardized thermal adhesive strength tester, and a series of compositions are prepared to confirm the thermal adhesive strength, and a specimen on the film is made to perform an adhesive test at various temperatures. Was carried out.

In this case, it is important to measure the temperature of the adhesive interface rather than the temperature of the seal bar itself of the adhesive, and it is possible to cause a slight difference between the measured temperature and the actual temperature due to the self-deviation or thermal conductivity of the thermal adhesive. shall.

To the resin composition according to the present invention, conventional additives, i.e., inorganic additives, pigments, antioxidants, antistatic agents, slip agents and the like can be added according to their purpose of use.

In the present invention, the resin composition had a melt index of between 0.1 and 5 at 190 ° C, and particularly in the range of 0.3 to 1.8, the high temperature processability was particularly excellent. In addition, when performing co-extrusion with a high heat-resistant resin such as polyamide, it was possible to stably produce a film even at a processing temperature of 250 ° C. or higher without a drop in viscosity or a blocking phenomenon between films during take-up.

Some of the objects and effects of the present invention are that film formation stability can be achieved even in a conventional film production apparatus, and blocking can be prevented even when coextrusion with a high temperature processed resin such as polyamide. In addition, the resin composition according to the present invention has a wide range of thermal bonding temperature, it is possible to obtain a film having a variety of adhesive strength from the easily detachable adhesive to the strong adhesive, which is why the paper, polyethylene film as a substrate Needless to say, aluminum foil can also be used.

Other objects and effects will become more apparent through the following embodiments, but the contents of the present invention are not limited to the scope of the embodiments.

Example 1

A low density polyethylene having a density of 0.921 and a melt index of 0.3 at 190 ° C. and 5% by weight of anhydrous millic anhydride were added and the low density polyethylene subjected to the graft reaction was mixed in a weight ratio of 8: 2. The melt index of this composition was 3 at 190 ° C.

The resin composition was co-extruded with a polyamide resin having a relative viscosity of 3.4 in a co-extrusion circular die having a diameter of 150 mm and a gap of 1.08 mm, and expanded at an expansion ratio of 1.8 with a wind speed of 40 m / min. Air having a temperature of 20 ° C. was blown into the resulting film to cool. The resulting film was stably maintained in a certain form without shaking or tearing and reached the take-out apparatus. The tube-like film that reaches the take-off plate changes shape into a flat plate and enters the take-up roll to form a completely flat two-layer film. These two layers of film were cut off at both ends by a winding device and wound around a paper tube with an inner diameter of 76 mm as a single layer of film. In this process, there was no winding problem caused by blocking and normal film winding was possible. Cut the film into 15mm width and 50mm length, and bond it with a low-density polyethylene film of 45g / m2 and melt index 1 under the conditions of bonding pressure 4bar, bonding length 3mm, bonding temperature 120 ~ 200 ℃ and bonding time 1 second The evaluation results are shown in Table-1.

TABLE 1

Example 2

A low density polyethylene having a density of 0,921 and a melt index of 1.8 at 190 ° C. and 10% by weight of maleic anhydride were added, and the high density polyethylene subjected to the graft reaction was mixed at a weight ratio of 8: 2. The melt index of this resin composition was 1.8 at 190 ° C.

The rest of the process was carried out in the same manner as in Example 1 and as a result of the test, stable film formation was possible and no blocking occurred.

The adhesion test results are shown in Table 2.

TABLE 2

Comparative Example 1

A low density polyethylene having a density of 0.921 and a melt index of 4 at 190 ° C. and 25% by weight of maleic anhydride were added and the low density polyethylene grafted to a mixture was mixed at a weight ratio of 8: 2. The melt index of this resin composition was 6 at 190 ° C.

However, with this resin composition, severe vibration of the film forming portion occurred and film molding was impossible.

Example 3

A low density polyethylene having a density of 0.921 and a melt index of 1.8 at 190 ° C. and 3% by weight of maleic anhydride were added, and the linear low density polyethylene grafted to a mixture was mixed at a weight ratio of 7: 3. At this time, the melt index of this resin composition was 4 at 190 ° C.

The test resulted in stable film forming and no blocking. Adhesion test results are shown in Table-3.

TABLE 3

Comparative Example 2

Low density polyethylene having a density of 0.921 and a melt index of 0.3 at 190 ° C. and 23% by weight of maleic anhydride were added, and the linear low density polyethylene grafted to a mixture was mixed at a weight ratio of 7: 3. At this time, the melt index of this resin composition was 6.2 at 190 degreeC.

As a result of the same method as in Example 1, the vibration of the film-forming part and blocking in the take-up roll occurred, and continuous operation was impossible.

Claims (4)

(A) 10 to 50% by weight of polyethylene graft reacted with 0.1 to 20% by weight of maleic anhydride (A) as a functional group, and (B) a melt index of 0.1 to 5 at 190 ° C and a density of 0.917 50 to 90% by weight of the low-density polyethylene is 0.9 to 0.927 and the melt index of the composition is a heat adhesive resin composition, characterized in that 0.1 to 5 at 190 ℃. The heat-adhesive resin composition according to claim 1, wherein the polyethylene grafted with maleic anhydride is low density polyethylene, high density polyethylene or linear low density polyethylene. A multilayer film, wherein the thermal adhesive resin composition of claim 1 is laminated on another resin film, so that the thermal adhesive resin composition forms an outermost layer. The multilayer film according to claim 3, wherein the resin film on which the heat-adhesive resin composition is laminated is polyamide, polycarbonate, polypropylene, or polyethylene terephthalate.