JPS60109834A - Film for laminating print - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print lamination film that can be laminated with printing paper or the like by only thermocompression bonding without using adhesives or organic solvents, and has good slip properties.

As is well known, paper products such as folding cartons, publications, cards, posters, and other printed matter are coated with plastic films for the purpose of protecting the printed surface, imparting water resistance, oil resistance, and beautification. Many of them are laminated.

Such processing is generally referred to as "print lamination" in the art.

Conventionally, this print lamination involves applying an adhesive dissolved in an organic solvent to the plastic film in the coating section of the laminator, scattering the organic solvent in the drying section, and then bonding the adhesive-coated IH 3 side of the plastic film to the printing paper. It is made by thermocompression bonding.

However, the method of using the above-mentioned ira solvent has problems in terms of work safety such as the risk of fire, as well as environmental protection such as the generation of odors and air pollution, and is also unfavorable from the viewpoint of saving resources. There has been a strong demand for a lamination method that does not require the use of organic solvents.

In view of these technical issues, the undeveloped IJJ was first filed in 1973 as a patent application.
No. 8-32892 discloses a new print lamination film that can be laminated with printing paper or the like by only thermocompression bonding without the need to use adhesives or solvents. The gist of this invention is a biaxially oriented polypropylene film in which a heat-sensitive adhesive resin layer is laminated with a polyethylene resin as the main component, and the surface of the heat-sensitive adhesive resin is subjected to a conventional surface treatment. In this case, the above-mentioned ordinary surface treatment refers to general chemical treatment, flame treatment, and corona discharge treatment. Furthermore, the unpublished IJII authors have also disclosed the same printed lamination film in Japanese Patent Application No. 57-133995, and the gist of this invention is a heat-sensitive adhesive resin layer containing polyethylene resin as the main component! It is a biaxially oriented polypropylene film with laminated layers, and the surface of the heat-sensitive adhesive resin layer is subjected to a corona discharge treatment in a nitrogen atmosphere with an ubricin concentration of less than 2 O.S by volume.

Various types of back layers can be considered as means for thermocompression laminating the thus obtained composite biaxially oriented polypropylene film (i.e., film for print lamination) and printing paper, and any known means may be used; For example, one of the thermocompression rolls is a heated metal roll and the other is a rubber roll, and the composite biaxially oriented polypropylene is bonded with a linear pressure of 5 kg/am or more, preferably 20 kg/c or more. The heat-sensitive adhesive resin layer of the system film and the printing surface of the printing paper are brought together, and the biaxially oriented polypropylene film layer of the composite biaxially oriented polypropylene film is brought into contact with the metal roll, and the printing paper is brought into contact with the rubber roll, respectively. The above laminating means is an outline of the film for printed lamination according to the present invention, and it is possible to laminate without using organic solvents, which has been a long-standing problem in the industry.
(This was an epoch-making invention that made this film possible.However, it was later discovered that this film had some problems in terms of production and practical use.In other words, the heat-sensitive adhesive resin layer was made of polyethylene-based 4&l resin. Because it is a soft layer, there are some areas where the slipperiness is insufficient, and in terms of manufacturing, the film tends to wrinkle easily during the slitting process, and in practical terms, static electricity is generated when the film is rolled out when laminated with printing paper. It has a slight problem that it has a tendency to absorb surrounding dust, clumps, etc.It is generally known that adding organic solvents or inorganic fine particles is a known method of imparting slipperiness to the film. However, if a large amount of organic lubricant is added to the heat-sensitive adhesive resin layer of this print lamination film, there is a disadvantage that the thermal adhesion with printing paper is economically reduced due to bleeding of the lubricant. If the fine particles of the system are added excessively, the transparency will be impaired, so there is a limit to the amount added in each case, and it has not been possible to obtain the desired good slipperiness.

The present inventors have conducted extensive research to solve these problems, and as a result, they have arrived at the present invention, and the 4. A film for print lamination, which is a scrap material, is made of a surface-treated heat-sensitive adhesive resin layer made of a mixture of 100 parts by weight of a polymer and 1 part of 5 to 300 iF of a polymer whose main component is propylene. This is what we are trying to provide.

Hereinafter, embodiments of unreleased 1jj will be described in detail below.

The biaxially oriented polypropylene film in the present invention is a boiling point! A polypropylene homopolymer with an n-hebutane extraction residue of 90% or more, a propylene-me-olefin copolymer with a mea-olefin content of 5 mol% or less, or a formulation with a total propylene content of 95 mol% or more. It refers to a mixture of a propylene monopolymer and a propylene-polyolefin copolymer, and further refers to a two-wheel stretched film made of the above polypropylene resin mixed with film waste generated during the production of the film of the present invention. Although there is no particular restriction on the thickness, a film having a thickness of 10 to 20p is usually preferably used. In addition, biaxially oriented polypropylene films with coloring or surface matte treatment, lubricants,
It goes without saying that products to which anti-blocking agents, stabilizers, ultraviolet absorbers, antistatic agents, etc. are added can also be used in the present invention.

The heat-sensitive adhesive resin layer laminated on the biaxially oriented polypropylene film is composed of 100 parts by weight of a polymer containing ethylene as a main component and 5 parts by weight of a polymer containing propylene as a main component.
300 parts by weight, and to give a more specific example, as a polymer containing ethylene as a main component, polyethylene or at least 7 o1f of ethylene is used.
! Examples include a copolymer containing 5% by weight, or a mixture of polymers having a total ethylene content of 70% by weight or more. At this time, there are no particular restrictions on the monomer to be copolymerized with ethylene, and any monomer that can be copolymerized with ethylene may be used. For example, propylene, butene-1, hexene-1, vinyl acetate, acrylic acid. Examples include ethyl and acrylic acid. Furthermore, those modified by copolymerization followed by hydrolysis or crosslinking with metal ions, and those modified by graft polymerization with maleic anhydride or the like can also be used in the present invention. However, if the total ethylene content is less than 70% by weight, film waste generated in the film manufacturing process or slitting process cannot be returned to the polypropylene layer and used, which is undesirable from the viewpoint of resource conservation. This is because, if these are intentionally returned, the transparency, slipperiness, dimensional stability, etc. will be significantly deteriorated, resulting in a biaxially oriented polypropylene film that cannot be used for practical purposes. Therefore, the total ethylene content is preferably at least 70% by weight, more preferably 85% by weight.

There are no particular restrictions on the propylene-based polymer that is used in combination with the ethylene-based polymer, such as a propylene-based polymer or a small amount, e.g., 40 mol% or less of ethylene, butene. Examples include copolymers with -1 and the like.

The heat-sensitive adhesive resin layer is preferably subjected to a corona discharge treatment in a nitrogen atmosphere as described below in order to provide thermal adhesion to printing paper, etc. The corona discharge treatment removes the ethylene as the main component. Due to the action of the polymer, the heat-sensitive adhesive resin layer becomes heat-adhesive to printing paper, etc., and on the other hand, the action of the polymer containing propylene as a main component significantly reduces the slipperiness of the surface of the heat-sensitive adhesive resin layer. It will be improved. In addition, since a polymer containing propylene as the main component is mixed into the heat-sensitive adhesive resin layer, the finished product does not lose its IJJ properties, does not change over time, and is easy to use in the film manufacturing process and slitting process. The film waste generated can be returned to the biaxially oriented polypropylene film and reused. As mentioned above, there are no other additives or polymers that have such a special effect, and from this fact as well, the significance of undeveloped IJ1 is clear. The amount of the propylene-based polymer to be mixed is 5 to 300 parts by weight, preferably 10 to 200 parts by weight, per 100 parts by weight of the ethylene-based polymer. If the amount is less than 5 ffi parts, the effect of improving slip properties will be small, and if it exceeds 300 parts by weight, thermal adhesion will be insufficient.
None of these are preferable.Additionally, lubricants, anti-blocking agents, stabilizers, color rejuvenators, ultraviolet absorbers, antistatic agents, etc. may be added to the heat-sensitive adhesive resin layer within a range that does not impair transparency or heat adhesive properties. Needless to say, the unreleased IJ1 will also be used.

Any known method may be used to produce the Pudding I lamination film, which is a laminate comprising a biaxially oriented polypropylene film layer and a heat-sensitive adhesive resin layer, according to the present invention. The thickness of the heat-sensitive adhesive resin layer may be appropriately selected depending on the smoothness of the printing paper surface, the required adhesive strength, etc., but it is usually preferable to have a thickness of 1 to 5P, but it also prevents the use of a thickness above 5P-Q. However, the layer thickness becomes unnecessary.゛The heat-sensitive adhesive resin layer has thermal adhesion to printing paper, etc. (・t'J
- 1 surface treatment is applied to Common treatment methods include chemical treatment, flame treatment, and corona discharge treatment, but corona discharge treatment is particularly effective. It is even more effective to perform discharge treatment. At this time, the effect is recognized when the residual oxygen concentration in the nitrogen atmosphere is less than 20.8 volume %, which is the oxygen concentration in air, which is 20.8 volume %, and the lower the residual oxygen concentration, the greater the effect. Preferably it is 5% by volume or less. Corona discharge treatment strength, film temperature during treatment, etc. may be appropriately selected depending on the desired adhesive strength, but generally 30 to 150 W/min and room temperature to 90°C are suitable. Any known method may be used to create a nitrogen atmosphere, such as enclosing the entire corona discharge treatment mechanism in a box and replacing the air inside with nitrogen gas, or spraying nitrogen gas into the corona discharge section through a slit or the like. is exemplified. Moreover, it goes without saying that there is no particular restriction on the surface treatment applied to the heat-sensitive adhesive resin layer, whether it is performed before lamination or after lamination.

Next, specific examples of the present invention will be described along with comparative examples. However, it goes without saying that the present invention is not limited to these examples.

<Example 1> Melt extrusion film of crystalline polypropylene (thickness ?50
p) in the longitudinal direction by a roll stretching machine at 130°C.
Stretched to 200%, and then applied 30% of each of the three types of formulations shown in Table 1 as a heat-sensitive adhesive resin layer on the longitudinally-axially stretched film.
Melt extrusion lamination to give p, then 160
℃, stretched 10 times in the transverse direction, and then the surface of the heat-sensitive adhesive resin layer was subjected to corona discharge treatment at a film temperature of 50'' and a C1 treatment intensity of 30 W min/m in a nitrogen atmosphere with a residual oxygen concentration of 0.05% by volume. As a result, a composite biaxially oriented polypropylene film, which is a laminate consisting of three types of biaxially oriented polypropylene film layers and a heat-sensitive adhesive resin layer, was obtained, that is, a film for print lamination.

Table 1: Numbers indicate parts by weight Kimoto formulation 1'&) 2 and 3 indicate comparative examples The three types of films obtained were each slittered to give widths. 80mm
The material was slit to a length of 2,000 m and rolled up into a 3-inch paper tube. The friction coefficients of the front/back surfaces of the three types of films thus obtained were as shown in Table 2.

Table-2 Coefficient of friction of various films These three types of films and printed coated paper were
A metal roll heated to 0°C and a linear pressure of 50. It was laminated by continuous thermocompression bonding between kg/cm rubber pinch rolls at a speed of 12 ml under the predetermined alignment conditions described above. However, in order to release the static electricity that is generated when the film is unfolded, there is a space between the film unwinding section and the thermocompression bonding section.
A grounded copper wire was passed across the film so that it touched the surface of the heat-sensitive adhesive resin layer. When the above-mentioned thermocompression bonding lamination was performed continuously, the films of composition No. 1 and composition No. 3 could be laminated up to the edge of the paper tube without any problem.
The film of composition No. 2 started to be laminated in a wrinkle-like manner after about 1,700 m of lamination, and the remaining 30 m
At about 0 m, a good printed laminated product was not obtained. This is because the film with formulation No. 2 had poor slip properties and was wrinkled during the slitting process. The thus obtained printed laminated product (the product of formulation No. 2 was a wrinkle-free laminated product up to 1,700 m long) was evaluated as follows. The results are shown in Table-3.

(1) Observation of dust and lumps Regarding 3 types of printed laminated products.

Randomly sample 100 sheets of each type, count the number of foreign objects caught in by static electricity, such as dust and clumps, with the naked eye, and measure 1.
Converted to number per square meter.

(2) Evaluation of adhesion The film was peeled off from the printing paper in a T-shape, and evaluated by the way the printing ink was removed to the film side.
ioH) About 50% of the ink was taken on the film side. Evaluation of various printed laminated products The present invention is as described above, and according to the present invention,
Not only have all the problems with conventional laminating methods that use organic solvents been eliminated, but also problems with slipperiness such as wrinkles and foreign matter being mixed in have been solved, making it even more desirable as a film for print lamination. .

On the other hand, the print-laminated products of Compound No. 2 and No. 3 mentioned above as comparative examples had some problems and could not be said to be suitable. This also shows the special effects of the present invention.

Patent applicant Gunze Co., Ltd.

Claims (3)

[Claims] (1) Surface-treated heat-sensitive adhesive resin consisting of a biaxially oriented polypropylene film layer, a mixture of 100 parts by weight of a polymer whose main component is ethylene, and 5 to 300 parts by weight of a polymer whose main component is propylene. A print lamination film characterized by being a laminate consisting of layers. (2) A patent claim in which the ethylene-based polymer is polyethylene, a copolymer containing at least 70% by weight of ethylene, or a mixture of polymers in which the ethylene content is 70% by weight or more. A film for print lamination as described in Scope 1. (3) The film for print lamination according to claim 1, wherein the surface treatment is a corona discharge treatment performed in an ungrooved nitrogen atmosphere with an oxygen concentration of 20.9% by volume.