CN114736623A - Heat laminated film - Google Patents

Abstract

The present invention relates to a heat laminated film having an ethylene vinyl acetate copolymer resin as an adhesive layer, which is excellent in adhesive force and has improved adhesion.

Description

Heat laminated film

Technical Field

The present invention relates to a thermal laminate film.

Background

The heat-laminated film is a film having a multilayer structure including an adhesive layer made of a heat-adhesive resin and a functional film layer, and the adhesive layer is attached to a substrate such as paper by applying heat and pressure, whereby not only the substrate can be protected, but also new functionality can be imparted by the functional film layer. In this case, a biaxially oriented polypropylene film (BOPP), a biaxially oriented polyethylene terephthalate film (PET), an oriented Nylon 6 film (Nylon), or the like can be used as the functional film. As the heat-adhesive resin, an ethylene vinyl acetate copolymer (hereinafter, abbreviated as EVA) resin is generally used.

One of the important characteristics of a heat-laminated film is excellent adhesiveness. When the adhesiveness to the substrate is insufficient, a peeling phenomenon occurs and the original object cannot be achieved. Recently, the technical trend of heat laminated films is that the demand for high adhesion is increasing with the increase of thin film coating, for example, thinning the coating thickness of 10 μm or more to 5 μm or less. In addition, with the trend of converting the printing method from an offset (offset) method using ink to a digital (digital) method using toner, higher adhesive force is also required.

The general physical properties of EVA resins are determined by the vinyl acetate monomer content in the resin, and it is known that the higher the vinyl acetate monomer content, the higher the adhesive force tends to be. However, when a film is produced using an EVA resin having a high vinyl acetate content, not only the adhesive strength but also the adhesiveness are increased, which causes a problem that it is difficult to use the final product in a roll form.

Therefore, it is desirable to produce a product which can realize high adhesion and little adhesion at the time of film coating.

As a prior art, korean patent laid-open publication No. 10-1760992 discloses a technique of extrusion-coating a polymer layer including polyolefin, a non-migrating slip agent and an anti-blocking agent on a metal substrate to have a reduced friction coefficient. In the technique, when a polymer layer is present on the surface, a reduced friction coefficient is imparted, but the adhesiveness and the cohesiveness when the polymer layer is used as an adhesive layer for lamination are not concerned. In addition, it is necessary to include both a non-migrating slip agent and an anti-blocking agent to exhibit such characteristics, and the anti-blocking agent has a large particle size of about several micrometers (μm), and is generally difficult to use in thermal lamination applications in which the thickness of the adhesive layer is 10 μm or less.

Disclosure of Invention

Problems to be solved by the invention

One embodiment of the present invention provides a high-quality thermal laminate film that suppresses generation of a bond while increasing adhesive strength.

Means for solving the problems

One embodiment of the present invention provides a thermal laminate film comprising an ethylene vinyl acetate copolymer resin as an adhesive layer, characterized in that the ethylene vinyl acetate copolymer resin comprises 20 to 32% by weight of a vinyl acetate monomer and an alkyl bis fatty acid amide derivative, the alkyl bis fatty acid amide derivative being contained to satisfy the following formula 1,

[ formula 1]

(1000/T) or more, the content (ppm) of the alkyl bis fatty acid amide derivative is not more than (5000/T),

(in the formula 1, the above-mentioned,

t is the thickness (mum) of the adhesive layer, and the content of the alkyl difatty acid amide derivative is the content of the alkyl difatty acid amide derivative in the ethylene-vinyl acetate copolymer resin).

The alkyl di-fatty acid amide derivative may be C₁₀To C₂₅The saturated or unsaturated straight-chain hydrocarbon fatty acid amide derivative of (4).

The adhesive layer may have a thickness of 2 μm to 20 μm.

Effects of the invention

The thermal laminate film according to one embodiment of the present invention has characteristics of excellent adhesion and less adhesion.

Detailed Description

The following examples are described in detail so that those skilled in the art can easily carry out the invention. However, the embodiments may be embodied in many different forms and are not limited to the embodiments described herein.

According to an embodiment, there is provided a thermal laminate film comprising an ethylene vinyl acetate copolymer resin as an adhesive layer, characterized in that the ethylene vinyl acetate copolymer resin comprises 20 to 32% by weight of a vinyl acetate monomer and an alkyl bis fatty acid amide derivative, the alkyl bis fatty acid amide derivative being contained to satisfy the following formula 1,

[ formula 1]

(1000/T) or more, the content (ppm) of the alkyl bis fatty acid amide derivative is not more than (5000/T),

(in the formula 1, the above-mentioned,

t is the thickness (mum) of the adhesive layer, and the content of the alkyl difatty acid amide derivative is the content of the alkyl difatty acid amide derivative in the ethylene-vinyl acetate copolymer resin).

The ethylene vinyl acetate copolymer resin may include 20 to 32% by weight of a vinyl acetate monomer. If the vinyl acetate monomer content is less than 20% by weight, a desired adhesive force with the substrate cannot be obtained, and if it exceeds 32% by weight, the adhesive force in a molten state is high, and the processing is difficult.

When a heat-laminated film is prepared and wound in the form of a final product, i.e., a roll, before being bonded to a substrate, a face of the functional film layer in contact with the adhesive layer is produced. When the ethylene vinyl acetate copolymer resin according to one embodiment is used as the adhesive layer of the heat laminated film, the presence of the alkyl difatty acid amide derivative on the surface of the adhesive layer can suppress the adhesion of the functional film layers different from each other to the adhesive layer.

The alkyl bis fatty acid amide derivative has migration properties in the ethylene vinyl acetate copolymer resin, migrates from the inside of the adhesive layer to the surface, and exhibits its efficacy. When the adhesive layer is thick, a large amount of the alkyl bis fatty acid amide derivative present inside the adhesive layer migrates to the surface and is present in excess, which results in a decrease in adhesion between the adhesive layer and the substrate after thermal bonding. Therefore, in order to produce a heat-laminated film in which neither adhesion nor damage of adhesive force occurs, the amount of the alkyl difatty acid amide derivative in the ethylene vinyl acetate copolymer resin may be defined in association with the thickness of the adhesive layer at the time of processing. For example, in the present invention, the thickness T (. mu.m) of the adhesive layer and the content of the alkyl bis fatty acid amide derivative in the ethylene vinyl acetate copolymer resin satisfy (1000/T). ltoreq.content (ppm). ltoreq.5000/T.

According to one embodiment, the alkyl difatty acid amide derivative may use C₁₀To C₂₅The saturated or unsaturated straight-chain hydrocarbon fatty acid amide derivative of (4).

The ethylene vinyl acetate copolymer resin may be prepared in a high pressure polymerization process, and the ethylene vinyl acetate copolymer resin thus prepared has a branched structure, imparting excellent processability during extrusion coating. The draw-in (rock-in) generated during the extrusion coating process is a phenomenon that the width of the film is reduced in the T-die (die) of the extruder, and is an important problem to be solved in the extrusion coating process. As the skilled person knows, the lower the retraction value the more advantageous, for which reason the value of the storage modulus G' measured at a loss modulus G "of 500Pa may be a value exceeding 50Pa (180 ℃). The storage modulus and the loss modulus are measured at a temperature of 180 ℃ and a shear rate in the range of 0.05 to 250 rad/s. When the storage modulus G' value fails to reach 50Pa, the elastic properties of the resin product are low, and recovery from tension is rapidly achieved during extrusion, resulting in an increase in the neck-in (neutral-in) property.

In the method of preparing a thermal laminate film according to an embodiment, the processing method may be an extrusion coating method or a co-extrusion method. The extrusion coating method is a method of extrusion coating an adhesive resin on the surface of a functional film prepared to form a multilayer film. In contrast, the coextrusion method refers to a process of processing a functional film and an adhesive layer at once using a multilayer film apparatus. In addition, the thickness of the adhesive layer at this time may be 2 μm to 20 μm. When the thickness of the adhesive layer is too thin, it is difficult to obtain a desired adhesive force, and when the thickness of the adhesive layer is too thick, an excessive amount of the alkyl bis fatty acid amide derivative in the adhesive layer may cause a decrease in the adhesive force.

The present invention is described in more detail below. However, this is for easy understanding of the present invention, and does not limit the scope of the present invention.

In the present experiment, polypropylene resin was used as the functional film layer. The polypropylene has a density of 0.910g/cm³And a melt flow index of 8.0g/10 min (230 ℃ C., 2.16 kg). The EVA (ethylene vinyl acetate) copolymer resin for the adhesive layer was prepared in a high pressure tubular process, and an EVA copolymer resin having the same melt flow index of 15g/10 min (190 ℃, 2.16kg) was used regardless of the VA (vinyl acetate) monomer content.

In addition, Ethylene bis oleamide (hereinafter abbreviated as EBO) of croda chemical co was used as the alkyl bis fatty acid amide derivative in this experiment.

Examples 1 to 4

According to the method of an embodiment, an EVA copolymer resin satisfying the conditions of table 1 below was used as an adhesive layer to prepare a heat-laminated film. The film processing method uses a coextrusion method.

Comparative example 1

An EVA copolymer resin satisfying the conditions of table 1 below was used as an adhesive layer to prepare a thermal laminate film. The same conditions as in example 1 were followed, except that the thickness of the adhesive layer was 50 μm.

Comparative example 2

An EVA copolymer resin satisfying the conditions of table 1 below was used as an adhesive layer to prepare a thermal laminate film. Prepared under the same conditions as in example 1 except that no EBO was added.

Comparative example 3

An EVA copolymer resin satisfying the conditions of table 1 below was used as an adhesive layer to prepare a thermal laminate film. The preparation was carried out under the same conditions as in example 1, except that 3000ppm of EBO was added.

Comparative example 4

An EVA copolymer resin satisfying the conditions of table 1 below was used as an adhesive layer to prepare a thermal laminate film. Prepared under the same conditions as example 1, except that the EVA copolymer resin used contains 18 wt% VA monomer and no EBO is added.

[ TABLE 1]

Examples of the experiments

Physical properties of the heat-laminated films of examples 1 to 4 and comparative examples 1 to 4 were measured, and the results thereof are shown in table 2 below. The evaluation items of the physical properties and the measurement methods thereof in the examples and comparative examples are as follows.

(1) Adhesive strength

The thermal laminated films prepared by examples and comparative examples were adhered to printing paper, and the strength at peeling was evaluated. The printed sheets were output using a Xerox digital printer and laminated at a temperature of 100 ℃ and a speed of 1.2 cm/s. The thickness of the sample was measured on a 25mm basis, and the 180 ℃ peel strength was measured at a speed of 200mm/min using a UTM apparatus.

(2) Adhesive strength

The thermal laminate films prepared in examples and comparative examples were artificially bonded, and the strength at peeling was evaluated. Using the two films, after an adhesive layer was attached to the functional film layer, the films were bonded to each other at 30 ℃ for 24 hours under 10 kg. The adhesive strength was evaluated according to ASTM D1893-67, and the film width at the time of evaluation was set to 60 mm.

[ TABLE 2 ]

As shown in table 2 above, examples 1 to 4 are thermal laminated films prepared according to the examples.

Although the content of the EBO is the same in comparative example 1 and example 2, the total amount of the EBO present in the layer is larger because the thickness of the adhesion layer of comparative example 1 is thicker. It can be confirmed that the adhesive strength of comparative example 1 is significantly lower than that of example 2. In addition, even though comparative example 1 and example 4 have the same thickness of the adhesive layer, the film of example 4 having the EBO content satisfying the range of formula 1 has little difference in bonding strength while being excellent in contact strength, compared to the film of comparative example 1 exceeding the range of formula 1.

Comparative example 2 is a film prepared without adding EBO, and the adhesive strength was higher than that of example 1.

Comparative example 3 showed an increase in the EBO content of 3000ppm and a very low adhesive strength compared to example 1.

The film prepared in comparative example 4 used a resin containing 18 wt% of VA monomer, which was most commonly used as a heat-laminated film. Examples 1 and 2 used a product containing 28 wt% of VA monomer, and thus exhibited higher adhesive strength than comparative example 4.

Further, when example 3 and example 4 are compared, it is understood that the film of example 3 included in the range of examples exhibits an excellent effect as an additional feature as compared with the film of example 4 which is relatively thick.

In the above comparison, the thermal laminate film prepared in the method of the present invention showed improved adhesive strength, and the adhesion showed improved effect.

Claims (3)

1. A thermal laminate film comprising an ethylene vinyl acetate copolymer resin as an adhesive layer,

the ethylene-vinyl acetate copolymer resin comprises 20-32 wt% of vinyl acetate monomer and alkyl double fatty acid amide derivative,

the alkyl bis fatty acid amide derivative contained satisfies the following formula 1,

[ formula 1]

(1000/T) or more, and the content ppm or less (5000/T) of the alkyl bis fatty acid amide derivative,

in the case of the above-mentioned formula 1,

t is the thickness of the adhesive layer, the unit is mum, and the content of the alkyl difatty acid amide derivative is the content of the alkyl difatty acid amide derivative in the ethylene-vinyl acetate copolymer resin.

2. The thermal laminate film as claimed in claim 1,

the alkyl di-fatty acid amide derivative is C₁₀To C₂₅The saturated or unsaturated straight-chain hydrocarbon fatty acid amide derivative of (4).

3. The thermal laminate film as claimed in claim 1,

the adhesive layer has a thickness of 2 to 20 μm.