KR20000066288A - polyolefinic film for thermal laminating - Google Patents

Abstract

PURPOSE: Provided is a polyolefin coextrusion film, that is capable of thermal lamination on the surface of a matrix such as a paper, a metal and a film, and has excellent optical properties and adhesive strength. CONSTITUTION: The film has a polypropylene resin layer as the center layer and coextruded surface layers on both sides, and at least one of surface layers is a corona-discharged thermal adhesive layer. The corona-discharged adhesive layer is composed of i)100pts.wt. of resin mixture consisting of 20-80pts.wt. of polyethylene resin and 20-80pts.wt. of polypropylene resin, wherein, a melting index of polyethylene resin is 1-15g/10min and a melting point of polypropylene resin is 145-165°C.; ii)1-5pts.wt of a thermal adhesion coagent having a molecular weight of 10,000 or less ; and then iii)0.5-1pts.wt. of a finishing coagent.

Description

Polyolefinic coextrusion film that can be thermally laminated {polyolefinic film for thermal laminating}

The present invention relates to a polyolefin-based coextrusion film capable of thermal lamination, and more particularly, to a polyolefin-based coextrusion film configured to be heat-bonded when laminating films on a substrate such as paper, metal or film.

In general, a method of laminating films on substrates such as papers, metals, films, and the like includes a thermal lamination method of applying heat to a heat-bonding surface having a low melting point and fusion, and an adhesive for each adhesive strength required for lamination. There is a dry lamination method of selecting and applying it to a substrate.

Until now, the thermal lamination method of the lamination method as described above has the heat adhesiveness required for thermal lamination only through an extrusion coating process of extruding a resin having a thermal adhesiveness to a general film on a substrate. However, the film for thermal lamination by the extrusion coating must be accompanied by an expensive auxiliary equipment required for the extrusion coating, and a further step is required to obtain the final laminate.

On the other hand, in the case of a dry lamination method for applying and bonding the adhesive to the substrate takes a separate adhesive, a separate adhesive coating facility and a drying facility for drying the adhesive is required. In addition, most adhesives have disadvantages that are not environmentally friendly.

Therefore, there is an urgent need to develop a co-extruded film that can replace the uneconomical and complicated lamination method as described above, that is, the lamination by heat without an extrusion coating process.

In order to meet such demands, a component having a thermal adhesive property on the surface used as an adhesive layer during lamination is formed in the form of a coextruded film, and is simply applied with heat to be laminated on a substrate to eliminate the process of extrusion coating or adhesive coating / drying. The film has been developed.

However, most of the thermally laminated film has a relatively expensive material such as ethylene vinyl acetate (EVA), ethylene-acrylic acid (EAA), maleic hydride copolymer, etc. .

In order to meet these disadvantages, development of a relatively low-cost, easy-to-manufacture polyolefin-based coextrusion film has been required. The present inventors have developed a film capable of thermal lamination as a polyolefin-based film in order to meet such demands.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coextruded film capable of thermal lamination having both the mechanical and optical properties inherent in a polyolefin resin while having the necessary adhesive force for thermal lamination.

The polyolefin-based coextruded film capable of thermal lamination of the present invention for achieving the above object is a film made of a polypropylene resin layer as a center layer and coextruded surface layers on both sides thereof, at least one surface layer being melted 100 parts by weight of a resin mixture consisting of 20 to 80 parts by weight of polyethylene resin having an index of 1 to 15 g / 10 minutes and 20 to 80 parts by weight of polypropylene resin having a melting point of 145 to 165 ° C, 1 to 5 parts by weight of a thermal bonding aid having a molecular weight of 10,000 or less It consists of 0.5-1 weight part of preparations, It is characterized by the thing of the heat bonding layer corona-discharge-processed.

The present invention will be described in more detail as follows.

The present invention relates to a polyolefin co-extruded film that allows heat bonding, wherein the center layer of the film is a polypropylene resin layer and a film having a three-layer structure in which surface layers are coextruded on both sides thereof.

In the present invention, in order to enable thermal bonding, at least one of the surface layers is formed as a thermal bonding layer. The main component resin of the thermal bonding layer is 20 to 80 parts by weight of polyethylene resin having a melt index of 1 to 15 g / 10 minutes and a melting point of 145 to 165. It consists of 20-80 weight part of polypropylene resins which are ° C.

In this case, when the melt index of the polyethylene resin is out of the above range, the film may be difficult to form due to the high flowability or the excessive extrusion load may occur due to the low flowability.

In addition, when the content of the polyethylene resin is out of the above range, an interlayer peeling phenomenon may occur at the heat-adhesive surface and the center layer during peeling after thermal lamination.

And, if the melting point of the polypropylene resin mixed with the polyethylene resin as described above is out of the range, a problem may occur that the mechanical properties are falling, if the content is out of the range as in the case of the content of polyethylene outside the range When peeling after thermal lamination, there is a problem that the interlayer peeling of the center layer and the heat-adhesive surface occurs.

1 to 5 parts by weight of the thermal bonding aid and 0.5 to 1 part by weight of the processing aid are mixed with respect to 100 parts by weight of the resin mixture as described above. In this case, the thermal adhesion aid includes a hydrocarbon-based resin or a hydrogenated hydrocarbon-based resin having a molecular weight of 10,000 or less. The same can be used.

When the content of the thermal bonding aid is less than 1 part by weight with respect to 100 parts by weight of the resin mixture, the effect as the thermal bonding aid is insignificant. When the content of the thermal bonding aid is greater than 5 parts by weight, the range of temperature setting during thermal lamination is narrowed. In view of such a point, the content of the preferred thermal bonding aid is 1.5 to 3 parts by weight.

Processing aids are added for film surface properties, and specific compounds include synthetic silica based, organic PMMA based or silicone based. Since the content thereof is 0.5 to 1 part by weight based on 100 parts by weight of the resin mixture, if the content of the processing aid is less than 0.5 parts by weight, the effect as a processing aid is insignificant, and if it exceeds 1 part by weight, the optical properties of the entire film are adversely affected. Not desirable

The thickness of the heat adhesive layer having the composition as described above is 5 to 40%, preferably 10 to 30% of the total film thickness.

At this time, when the thickness of the thermal adhesive layer is less than 5% of the total film thickness, the thermal adhesive strength is weak and it is difficult to control the adhesive strength during thermal lamination. On the other hand, if the thickness is more than 40% of the total film thickness, the thermal adhesion strength during the thermal lamination is strong, but the mechanical properties of the entire film is deteriorated and adversely affect the optical properties, that is, transparency or gloss.

The heat adhesive layer having the above characteristics is corona discharged to secondarily adjust the heat adhesive strength.

On the other hand, as the center layer of the polyolefin coextruded film of the present invention, it is preferable to use polypropylene having a melting point of 145 to 165 캜 for post processing, for example, molding and workability.

In addition, the surface layer located on the opposite side of the heat-adhesive layer based on the central layer has 95 to 98 parts by weight of polypropylene having a melting point of 145 to 165 ° C. for processing and mechanical properties. Addition was made.

At this time, the melting point of the polypropylene outside the above range may cause a problem of poor mechanical properties, the additive may be a synthetic silica-based, organic PMMA-based or silicon-based.

As described above, using a three-layered film in which the surface layer and the heat-adhesive layer are coextruded on both sides of the polypropylene resin layer as described above, the thermal adhesion strength required for each substrate is different. In addition, by adjusting the composition ratio of the above-mentioned heat-adhesive layer, it is possible to give the most suitable adhesive force to papers, aluminum foils, iron plates, films.

On the other hand, in the manufacture of a film capable of thermal lamination according to the present invention, additives, specifically antioxidants, antistatic agents, stabilizers, and the like, which are commonly known to be added in film production, are not deteriorated within the range of not impairing the physical properties of the film of the present invention. You may add it.

The film of the present invention is coextruded into a non-stretched film using a polyolefin resin, and the thermal adhesive strength of the thermal lamination film manufactured according to the above production method is also applied to the type of laminated substrate (papers, films, aluminum foils, iron sheets). And its control is distinguished by the composition of the resin used in the heat-adhesive layer.

At the time of co-extrusion, the heat bondable temperature is 100 degreeC or more.

According to the type of laminated materials, the use can be applied to various packaging materials such as syringe packaging, book cover, and medical packaging materials.In case of film and aluminum foil, it can be laminated as a film used as a support. Used for surface protection of industrial steels.

The biggest feature of the film according to the present invention is that the heat-adhesive layer is made of pure polyolefin, which is economical as compared with conventional co-extrusion films for thermal lamination such as EVA and EAA, and exhibits the inherent characteristics of the polyolefin-based resin itself.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

The center layer used a polypropylene resin having a melting point of 145 to 165 캜 and a melt index of 1 to 15 g / 10 minutes.

The heat-bonding layer is composed of a heat-adhesive aid having a molecular weight of 10,000 or less in 100 parts by weight of a resin mixture obtained by mixing 30 parts by weight of polypropylene having a melting point of 145 to 165 ° C. and a polyethylene resin having a melt index of 1 to 12 g / 10 minutes by 70 parts by weight. , Kolon Emulsified Products) 2 parts by weight, a processing aid (synthetic silica-based, Korea Emulsified Products, organic PMMA-based, Docello products) was used was mixed and used to produce a non-stretched film by corona discharge treatment. The surface layer was melted at a melting point of 145 to 165 DEG C, a melt index of 1 to 15 g / 10 minutes, and composed of 97 parts by weight of polypropylene and 3 parts by weight of a processing aid (synthetic silica, organic PMMA). Coextrusion produced a film.

The thickness of the heat-adhesive layer in the film was 15% of the total film thickness, and as a result it was prepared as a 90μ thick undrawn coextruded film.

Example 2

A resin mixture 100 was prepared in the same manner as in Example 1, except that 30 parts by weight of a polypropylene resin having a melting point of 160 to 165 ° C. was melted and 70 parts by weight of a polyethylene resin having a melt index of 1.0 to 3.0 g / 10 minutes. The processing aid and the thermal bonding aid in parts by weight were the same as in Example 1.

Example 3

100 wt% of a resin mixture prepared in the same manner as in Example 1, except that 30 parts by weight of a polypropylene resin having a melting point of 152 to 157 ° C. and 70 parts by weight of a polyethylene resin having a melt index of 12 to 15 g / 10 min. The processing aid and the heat adhesion aid were the same as in Example 1 above.

Example 4

A film was prepared in the same manner as in Example 1 except that the composition of the polypropylene polypropylene having a melting point of 160 to 165 ° C. was used.

Example 5

A film was prepared in the same manner as in Example 1 except that 50 parts by weight of polypropylene having a melting point of 160 to 165 ° C. and 50 parts by weight of polypropylene having a melting point of 152 to 157 ° C. were used. It was.

Example 6

A film was prepared in the same manner as in Example 1 except that 50 parts by weight of polypropylene having a melting point of 152 to 157 ° C. and 50 parts by weight of polypropylene having a melting point of 145 to 150 ° C. were used. It was.

Example 7

A film was prepared in the same manner as in Example 1 except that 50 parts by weight of polypropylene having a melting point of 152 to 157 ° C. and 50 parts by weight of polypropylene having a melting point of 145 to 150 ° C. were used. It was.

Example 8

A film was prepared in the same manner as in Example 1 except that polypropylene having a melting point of 145 to 150 ° C. was used alone.

Comparative Example 1

A film was prepared in the same manner as in Example 1, except that 90 wt. Parts of polypropylene resin was used in the thermal adhesive layer composition to prepare a non-stretched film.

Comparative Example 2

A film was prepared in the same manner as in Example 1 except that a non-stretched film was prepared using 10 parts by weight of a polypropylene resin in the heat-adhesive layer composition.

Comparative Example 3

A film was prepared in the same manner as in Example 1, except that 0.05 parts by weight of a thermal bonding aid and a processing aid were added in the thermal bonding layer to prepare a non-stretched film.

Comparative Example 4

A film was prepared in the same manner as in Example 1, except that 5 parts by weight of a thermal bonding aid and a processing aid were added in the thermal bonding layer to prepare a non-stretched film.

Comparative Example 5

A film was prepared in the same manner as in Example 1, except that a non-stretched film was prepared using a heat adhesive layer having a thickness of 3% of the total film thickness.

Comparative Example 6

A film was prepared in the same manner as in Example 1, except that the non-stretched film was prepared using a heat adhesive layer having a thickness of 45% of the total film thickness.

Comparative Example 7

The film was prepared in the same manner as in Example 1, except that the corona discharge treatment was omitted in the thermal adhesive layer.

Comparative Example 8

A film was prepared in the same manner as in Example 1 except that polypropylene having a melting point of 152 to 157 ° C. was used alone.

Experimental Example 1

For the films prepared according to the above Examples and Comparative Examples, the heat adhesion strength and the thermal lamination after the thermal lamination were measured, and the results are shown in Table 1 below.

This thermal adhesion was performed using a rubber roll that can be controlled by an electric heater, and the test method is to change the temperature at a predetermined speed and to pass the substrate and the film in close contact between the two rolls. ).

Here, the measurement of the thermal adhesive strength of the film is a case where there is no transition of the thermal adhesive layer on the substrate at the time of peeling after thermal bonding with a substrate such as paper, aluminum foil, iron plate or film, and partial adhesive layer transition (1/5 of the adhesive area). ▲, partial adhesion layer transition (1/5 to 4/5 of the adhesion area) occurs, and partial adhesion layer transition (4/5 to 4.5 / 5 of the adhesion area) occurs. (Circle) and the case where the transfer | transformation of an adhesive layer 100% have been represented by (circle).

In the interlayer peeling between the center layer and the adhesive layer after thermal lamination, the case where there was no interlayer peeling at the time of peeling was indicated by N and the case where the interlayer peeling occurred was Y.

Adhesive strength Separation of the center layer and adhesive layer after thermal lamination Temperature (℃) Paper Aluminum foil Iron plate Film Example 1 100 ▲ △ △ ▲ N 110 ◎ ▲ ▲ ○ N 120 ● ◎ ◎ ◎ N 130 ● ● ◎ ● N Comparative Example 1 100 △ △ △ △ N 110 △ △ △ ○ Y 120 ○ ○ ▲ ◎ Y 130 ◎ ◎ ○ ● Y Comparative Example 2 100 △ △ △ ◎ N 110 ○ ○ ▲ ● Y 120 ● ● ● ● Y 130 ● ● ◎ ● Y Comparative Example 3 100 △ △ △ △ N 110 ▲ △ △ ▲ N 120 ◎ ◎ ▲ ◎ N 130 ◎ ◎ ○ ◎ N Comparative Example 4 100 ▲ ▲ △ ○ N 110 ◎ ◎ ○ ◎ N 120 ● ● ◎ ● N 130 ● ● ● ● N Comparative Example 5 100 △ △ △ △ N 110 ▲ ▲ △ ▲ N 120 ▲ ▲ ▲ ▲ N 130 ○ ○ ▲ ○ Y Comparative Example 6 100 ▲ ▲ ▲ ▲ N 110 ◎ ◎ ○ ◎ N 120 ● ● ◎ ● N 130 ● ● ● ● N Comparative Example 7 100 △ △ △ △ N 110 △ △ △ △ N 120 ▲ △ △ ▲ N 130 ○ △ △ ○ N

From the results of Table 1, it can be seen that the film produced by constructing the heat-adhesive layer according to the present invention has excellent adhesive strength and no peeling after thermal lamination.

Experimental Example 2

The transparency and glossiness of the films prepared according to Examples 1 to 8 were measured, and the results are shown in Table 2 below.

Here, transparency was measured according to the ASTM D1003 method, glossiness was measured according to the ASTM D2457 method.

Transparency (HAZE),% Glossiness,% Example 1 9.0 or less 65 or more Example 2 13.0 or less 50 or less Example 3 11.0 or less 55 or less Example 4 12 or more 50 or less Example 5 11 or more 55 or less Example 6 10.5 or less 55 or less Example 7 8.5 or less 70 or less Example 8 8.0 or less 75 or less

From the results of Table 2, it can be seen that the film according to the present invention has a relatively excellent optical property in comparison with the other embodiments also in optical properties, that is, transparency or glossiness, and also within the scope of the present invention, that is, thermal It can be seen that the mechanical strength and optical properties vary depending on the polypropylene composition of the other core layer and the surface layer on the premise that the layer has the necessary thermal adhesive force, and thus it can be selectively used according to the end use of the present invention.

As described in detail above, a film prepared by co-extrusion of a heat-adhesive layer and a surface layer of a specific composition on both surfaces thereof with a polypropylene resin according to the present invention is typically thermally laminated on the surface of a substrate and used. It is excellent in optical properties, adhesive strength, and the like, and there is an inexpensive effect by using a polypropylene resin.

Claims (5)

A film made of a polypropylene resin layer as a center layer and coextruded with surface layers on both sides thereof, At least one surface layer is 100 parts by weight of a resin mixture consisting of 20 to 80 parts by weight of a polyethylene resin having a melt index of 1 to 15 g / 10 minutes and 20 to 80 parts by weight of a polypropylene resin having a melting point of 145 to 165 ° C. A polyolefin-based coextrusion film capable of thermal lamination, comprising -5 parts by weight and 0.5-1 part by weight of a processing aid, wherein the thermal bonding layer is a corona discharge treatment. The polyolefin-based coextrusion film according to claim 1, wherein the thermal adhesive layer has a thickness of 5 to 40% of the total film thickness. The polyolefin-based coextruded film according to claim 1, wherein the center layer is made of a polypropylene resin having a melting point of 145 to 165 캜. The polyolefin-based coextrusion film according to claim 1, wherein the surface layer is composed of 95 to 98 parts by weight of a polypropylene resin having a melting point of 145 to 165 ° C and 2 to 5 parts by weight of an additive. The polyolefin-based coextruded film according to claim 1, wherein the heat-adhesive temperature of the center layer, the heat-adhesive layer, and the surface layer is 100 ° C or more.