KR100550964B1 - Resin composition for heat-resistant easy-peel films - Google Patents

Abstract

The present invention relates to a resin composition for easy peel film, and more particularly, to a resin composition for easy peel film that can be used in a microwave oven made of a high density polyethylene resin, a polypropylene resin and a linear low density polyethylene resin.

Description

Resin composition for easy-fill film with heat resistance {RESIN COMPOSITION FOR HEAT-RESISTANT EASY-PEEL FILMS}

The present invention relates to a resin composition for easy peel film, and more particularly, to a resin composition for easy peel film improved heat resistance consisting of a high density polyethylene resin, a polypropylene resin and a linear low density polyethylene resin.

The concept of food packaging until the early 90s was very important for the long-term preservation of food, but recently, with the advancement of the industrial structure, the concept of packaging, along with the development of the instant industry, the development of the pharmaceutical industry, and the development of the dessert industry It is a trend that is shifting from the concept of preservation to the design and sensory aspects, and the one that appeared as an easy peel film is easy to open.

The easy-fill film is composed of polymers having different compatibility, and is made by maintaining a suitable balance of compatibility characteristics and incompatibility between the substrate and the film when heat-sealed to the adhesive substrate. The commercial property can securely preserve the contents by securing strong adhesive force, and the non-commercial property gives the opening property so that it can be easily opened when opened.

The key technology in the manufacture of these easy-fill films is to select suitable polymers with different compatibility, to ensure proper mixing ratio between them, and to secure appropriate processing conditions to stabilize the morphology of the continuous and dispersed phases.

According to Japanese Patent Laid-Open No. 6-328639, an easy-fill film was composed of polybutene, polyethylene, and polypropylene, and was applied to a polypropylene container. In this case, it showed excellent properties in terms of securing transparency and low temperature adhesion. However, since polybutene's unit price is very high, it is required to develop an easy-fill film by using a relatively low-cost product in terms of economy.

In Japanese Patent Laid-Open No. 6-287417, an easy-fill film was manufactured using polystyrene, which is very economically cheaper than polybutene. However, this product can be applied as a casting method, but there is a fatal problem in transparency during blown film forming. Especially, when the sterilization temperature exceeds 120 ℃, rubbing the film by hand causes the phenomenon that occurs on the surface of the film. Application to microwave sterilization products with high sterilization temperature was difficult.

An object of the present invention is to improve the above problems, it is possible to lower the manufacturing cost of the product by using a general-purpose resin, and also improve the heat resistance of the film can be applied for microwave oven resin composition for easy-fill film To provide.

The resin composition for easy-fill film of the present invention is characterized by consisting of 40 to 90% by weight of high density polyethylene, 5 to 30% by weight of polypropylene and 5 to 30% by weight of linear low density polyethylene.

In the resin composition for easy-fill film of the present invention, a high-density polyethylene (HDPE) having a melting temperature of 125 ° C or higher is used as the base resin. At this time, the usage-amount of high density polyethylene is 40 to 90 weight% with respect to the whole resin composition, It is preferable to use 60 to 70 weight% more preferably.

When the amount of high-density polyethylene used is less than 40% by weight, the amount of resin added is increased, so phase transition on morphology may occur frequently even in the slight change of processing conditions, resulting in poor film thickness due to uneven distribution of incompatible resins. In addition, when adhesion to a polypropylene container with heat, the unevenness of the adhesion site increases (dispersion failure), so that the adhesive strength is too strong in some areas, and the easy peeling function is lost in some areas, There is a fear that the sealing part is opened by the impact from the outside and the contents may leak out. In addition, when the amount of use exceeds 90% by weight, not only the workability deterioration due to the resin pressure and the load increase, but also the adhesion strength to the polypropylene container is too weak, there is a risk of losing the basic concept of the packaging material.

In the resin composition for easy-fill film of the present invention, 5 to 30% by weight of the polypropylene (PP) used to exhibit a strong adhesive force when applied to a polypropylene container and to safely preserve the contents is used. When the amount is less than 5% by weight, the adhesive strength is low, so it cannot be used as a packaging material for polypropylene containers. When the content exceeds 30% by weight, the adhesive strength is so strong that the easy peel function is lost.

In the resin composition for easy-fill film of the present invention, the linear low density polyethylene (LLDPE) has a solubility constant of about medium between high density polypropylene and polypropylene, and thus serves as a compatibilizer between high density polyethylene and polypropylene. The morphology of the film is stabilized so that the film exhibits uniform physical properties over the entire site, and the content thereof is 5 to 30% by weight based on the total resin composition. When the content of the linear low density polyethylene is less than 5% by weight can not be expected to stabilize the morphology, if the content exceeds 30% by weight may cause problems in heat resistance.

The present invention can be understood in more detail by the following examples and comparative examples, the following examples are only for illustrating the present invention and are not intended to limit the protection scope of the present invention.

Examples 1-4

According to the composition shown in Table 1, each component was melt-blended and pelletized at 210 ° C. in a 30ψ twin screw extruder, and then the film was molded to a thickness of 30 μm in a blown film molding machine. The laminated film of PET film having a thickness of 16 μm on the molded film was heat-laminated to a polypropylene sheet and a container, and then peeling strength and heat resistance were measured by the following method, and the results are shown in Table 1 below.

Measurement of peeling strength

The size of the film and the adhesive material (polypropylene sheet: thickness 250 µm) was cut into a size of 5 cm x 30 cm, respectively, to prepare a specimen, and the film was thermally bonded to a size of 25 mm x 10 mm on the polypropylene sheet. Fusion temperature was 20 ℃ interval in the range of 200 ℃ ~ 240 ℃, pressure and time were 2kgf / cm ² , 1 ^second , respectively. The heat-sealed specimens were cut to a size of 15 mm x 10 mm and longitudinally peeled in the UTM. The highest value of the strength measured at this time was selected as the peeling strength. Tensile velocity was measured at a rate of 200 mm / min.

If the peeling strength is too strong, the film is stretched or torn. Of course, if the peeling strength is too weak, the role of the packaging will be lost, so maintaining the proper level of peeling strength is important. Typically, peeling strength that can be opened by adults is less than 2.0kg / 15mm is appropriate for microwave oven 0.8 ~ 2.0kg / 15mm level.

Heat resistance rating

The PET laminated film was cut into 10 cm x 10 cm sized specimens, and a polypropylene container was used having a rounded diameter of 5 cm. At this time, the width of the heat-sealed portion with the film was 5mm. About 70% of edibles were put in a polypropylene container, and a 10 cm × 10 cm sized easy-fill film on which PET was laminated was placed and heat-sealed at 200 ° C. The fusion pressure was 7kgf / cm ² and the time was 0.5 seconds. The polypropylene container was placed in an autoclave and sterilized at 120 ° C. for 30 minutes, and then the thermal resistance evaluation of the film was carried out by visual observation at room temperature and the lid of the container. The main points of sensory evaluation were whether the lid was contracted by heat, whether the heat sealing area was opened and the contents leaked out, and whether the easy peel function appeared after the sterilization process.

For microwave use, sterilization should be done at 120 ℃ for 30 minutes immediately after packing the contents. Therefore, in order to be applicable for a microwave oven, the heat resistance of the film must withstand 30 minutes at 120 ℃.

Comparative Examples 1 to 4

According to the composition shown in Table 1, each component was melt-blended and pelletized at 210 ° C. in a 30ψ twin screw extruder, and then the film was molded to a thickness of 30 μm in a blown film molding machine. On the molded film, PET films having a thickness of 16 µm each were dry laminated and then heat-sealed to the polypropylene sheet and the container. Evaluation of the peeling strength and heat resistance of the copper film was carried out in the same manner as in Example 1, the results are shown in Table 1.

Table 1

As can be seen from Table 1, by using the resin composition of the present invention consisting of 40 to 90% by weight of high density polyethylene, 5 to 30% by weight of polypropylene, and 5 to 30% by weight of linear low density polyethylene, the results were quite excellent in peeling strength and heat resistance. Could get

As can be seen from the above, the resin composition prepared according to the present invention has an excellent easy peel performance, excellent peeling strength, and also has excellent heat resistance to be applicable to a microwave oven.

Claims (1)

A resin composition for easy-fill film, comprising 40 to 90% by weight of high density polyethylene, 5 to 30% by weight of polypropylene and 5 to 30% by weight of linear low density polyethylene.