JPH066635B2 - Surface modification method for plastic film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for modifying both surfaces of a plastic film by graft-polymerizing the same or different surface modifying monomers on both surfaces of the plastic film.

(Prior Art) As a method of modifying the surface of a conventional plastic film to give a new function, (1) a different type of polymer is adhered, or a solution thereof is applied and dried to form a different type of film on the surface of the film. A method of forming a polymer layer, (2) a method of polymerizing a monomer on the surface of a plastic film by a catalytic reaction, and chemically bonding a different kind of polymer to the surface are known.

(Problems to be Solved by the Invention) However, the method (1) has a problem in durability because the adhesion between the plastic film and the polymer layer is poor. On the other hand (2)
The method of (1) has excellent durability because the different types of polymer are chemically bonded, but it is difficult to polymerize the monomer only on the film surface, and it is a difficult process that must be solved for industrialization. Contains.

(Means for Solving the Problems) Then, as a result of intensive investigations by the present inventors in order to solve the above-mentioned problems, as a result, a liquid layer of the same or different surface-modifying monomers on both surfaces of the plastic film After providing liquid layers and stacking sheet-shaped materials on each liquid layer, electron beam is irradiated from the sheet-shaped material side to graft-polymerize the monomers of the liquid layer on both sides of the plastic film, and then laminated sheet-shaped The material was peeled from both sides of the plastic film, and the surface of the plastic film was modified by a method of removing the unreacted monomer or the monomer solution remaining on both sides of the plastic film.

In the present invention, the reason why the liquid layer of the monomer or the monomer solution is provided on both surfaces of the plastic film and the on-sheet material is laminated thereon is to make the liquid layer thin and uniform. If the liquid layer is still provided on the film surface, the surface of the plastic film is a low energy surface, and therefore the liquid layer of the monomer or the monomer solution becomes discontinuous and a uniform film cannot be formed. However, when the sheet-shaped material is laminated on the liquid layer, the monomer or the monomer solution can be held thinly and uniformly between the plastic film and the sheet-shaped material by the capillary action.

In the present invention, the liquid layer is made thin and uniform as described above, and the monomer is graft-polymerized on the plastic film with an electron beam.
That is, when the electron beam is irradiated from the laminated sheet-shaped material side, the electron beam easily penetrates the liquid layer and reaches the surface of the plastic film to generate radicals in the film. When radicals are generated, those generated on the surface among the generated radicals react with the monomers adjacent to the surface, and the monomers undergo graft polymerization. At this time, since the graft polymerization of the monomer in the film depth direction can be adjusted by the irradiation electron dose, the polymerization depth can be made uniform throughout.

However, if the sheet material is peeled from both sides after electron beam irradiation and the unreacted monomer or monomer solution on the surface of the organic resin is removed, only the graft-polymerized monomer remains on the surface of the plastic film and the surface is modified. You can

In the present invention, the monomer in the liquid layer provided on both surfaces of the plastic film may be one having an electron beam reactive functional group (ethylenically unsaturated double bond), and it may be a monomer simple substance or a polymer such as Mohr's salt. It may be added with an inhibitor. The liquid layer may be provided by a known method such as spraying, curtain flow or roll coating. The sheet-like material laminated on the liquid layer is laminated so as to be in close contact with the plastic film via the liquid layer. As the sheet-shaped material, a plastic film, a metal film vapor-deposited on this film, metal foil, paper, resin-coated paper, metal vapor-deposited paper, or the like is used.

Since the monomer is covered with the sheet-shaped material, the irradiation of radiation may be carried out in an air atmosphere without deterioration of graft polymerization due to oxygen.

According to the method of the present invention, the surface of most plastic films can be modified, and even polyolefin, polyurethane, polyamide, polystyrene, polyvinyl chloride, polyester or polyvinyl alcohol can be modified.

(Example) Example 1 Biaxially stretched polyethylene terephthalate film (thickness 50
While applying methacryl powder on the bar coater # 30, a high-density polyethylene film (thickness: 50 μm)
m) is laminated, a liquid layer of methacrylic acid is first provided on the lower surface of the high density polyethylene film, and then trifluoroethylene methacrylate is applied on the upper surface of the film in the same manner as above, while a biaxially stretched polyethylene terephthalate film ( A thickness of 50 μm) was laminated and a liquid layer of trifluoroethyl methacrylate was provided on the upper surface.

Then, from the top side, acceleration voltage 200 KeV, electron current 10 mA,
An electron beam was irradiated under the condition of a dose of 5 Mrad to graft-polymerize methacrylic acid and trifluoroethyl methacrylate on the lower surface and the upper surface, respectively. After polymerization, the biaxially stretched polyethylene terephthalate film on both sides was removed, and the surface was ultrasonically washed in methanol for 10 minutes and dried.

When the contact angle of the film with water after drying was measured,
The lower surface of the graft-polymerized methacrylic acid was 56 °, the upper surface of the graft-polymerized trifluoroethyl methacrylate was 113 °, and the lower surface was fresh water, but the upper surface was Water repellency was imparted.

Example 2 An ethylene-tetrafluoroethylene copolymer film was used in place of the high-density polyethylene film of the surface-modifying film in Example 1, and methacrylic acid was used instead of trifluoroethyl methacrylate as a liquid layer provided on the upper surface. Using 2-hydroxyethyl, the surface of the ethylene-tetrafluoroethylene copolymer film was modified in the same manner as in Example 1.

As a result, the contact angle to water was 86 ° in the case of the lower surface modified with methacrylic acid and 93 ° in the case of the upper surface modified with 2-hydroxyethyl methacrylate, which showed that the untreated ethylene-
Hydrophilicity was imparted to both surfaces of the tetrafluoroethylene copolymer film at 108 °.

(Effect) As described above, the present invention is modified by graft-polymerizing a monomer on the surface of a plastic film to form a polymer different from the film on the surface.
The bond between the plastic film and the polymer is strong. Further, since the graft polymerization is carried out by irradiation electron beam, the monomer graft polymerization depth in the film can be made constant over the entire surface if the dose is made constant. Furthermore, since the graft polymerization is carried out by holding the monomer or its solution thinly and uniformly on both sides of the plastic film with a sheet-shaped material, the monomer can be graft-polymerized even with a low-voltage electron accelerator (accelerating voltage 350 KeV or less), and easily. Can be industrialized.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Masuhara 1 at 7 Ichikawa Research Laboratories, Takatani Shinmachi, Ichikawa City, Chiba Prefecture (56) Reference JP-A-60-13823 (JP, A)

Claims (1)

[Claims] 1. A liquid layer of the same or different surface-modifying monomers or a liquid layer of these monomer solutions is provided on both sides of a plastic film, and a sheet-shaped material is laminated on each of the liquid layers, and then a sheet-shaped material is formed. Irradiate an electron beam from the material side,
A plastic characterized by graft-polymerizing a liquid layer monomer on both sides of a plastic film, and then peeling the laminated sheet material from both sides of the plastic film to remove unreacted monomer or monomer solution remaining on both sides of the plastic film. Film surface modification method.