JPH0419912B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing a coated web using a radiation-curable coating agent. <Prior Art> Since the curing reaction of a radiation-curable coating agent mainly proceeds through a radical reaction, the reaction is inhibited by oxygen in the air. Therefore, the curing of these coating agents is generally carried out in an inert gas atmosphere or by laminating a laminate material on the surface of the applied coating agent to block oxygen. As an improvement to the latter method using a laminate material, the present inventors first developed a method for blocking oxygen when curing a coating agent applied to a continuously running strip-shaped support (hereinafter referred to as a web) with radiation. Japanese Patent Application No. 58-221052 proposes a method of irradiating the laminated portion of the web with radiation as a laminate material before coating or after coating irradiation, and using one continuous roll of web as a laminate material. did. However, in this method, it is necessary that the front and back surfaces of the same web have contradictory properties such as adhesion and releasability to the cured coating agent.
For this reason, it is essential that the web used be subjected to surface treatment such as a primer, back treatment agent, or corona treatment.
Usually, this was done using a web whose coating surface had been previously treated with corona. <Problems to be Solved by the Invention> However, in the past, this corona treatment and the application of the coating agent were performed separately, resulting in deterioration over time before use, and damage to the support rolls, winding, and Damage and abrasion of the treated surface due to friction with the web during unwinding could not be ignored. In addition, dedicated unwinding and winding equipment for corona treatment and its installation location are required. Furthermore, the storage location, movement, and replacement work of the processed web was complicated. The present invention has been made in view of the above situation, and is intended to solve the above-mentioned problems. <Means for Solving the Problems> In other words, the present invention runs a web fed out from one end in a closed loop so that a leading web and a trailing web form an overlapping part, and coats the surface of the leading web. A method for producing a coated web, which comprises superimposing the back side of a trailing web on the radiation-curable coating agent, irradiating the overlapping portion with radiation to crosslink and cure it, and then peeling off the trailing web. This method is characterized in that the surface of the preceding web is subjected to corona treatment immediately before coating. The method of the present invention will be explained below with reference to the drawings. A web 1 is unwound from a raw web, passes through laminating rolls 2 and 3 and a group of guide rolls, and then its surface is corona treated by a corona treatment device 4.
Immediately thereafter, the coating is applied by the coating device 5 and laminated (laminated) on the back side of the web 1 which is later fed out by the laminating rolls 2 and 3, and after curing by irradiating with radiation from the radiation source 6 while blocking oxygen, the coating is superimposed. The resulting web is peeled off and wound up to form a product 7. The web used in the present invention includes paper,
Examples include cloth, plastic film, foam, metal foil, and composites thereof. Examples of the coating agent used in the present invention include paints, adhesives, pressure-sensitive adhesives, and printing inks that are cured by radiation. The main components or additives of these coating agents must have reactive unsaturated double bonds that cause a curing reaction when exposed to radiation energy. Examples of radiation-reactive unsaturated double bonds include unsaturated double bonds such as acrylic, methacrylic, allyl, and vinylene, but acrylic double bonds are preferred from the viewpoint of reactivity. Further, it may be one having an epoxy group that is ionically polymerized with a Lewis acid initiator or the like. Further, a chain transfer agent is added to adjust the reactivity, and various additives are added depending on the intended use to prepare the coating agent. The radiation used in the present invention includes active energy rays such as α rays, β rays, γ rays, neutron beams, ionizing radiation such as accelerated electron beams, and ultraviolet rays. The corona treatment may be performed using any of the commonly used spark gap vacuum tube methods and solid state methods. However, it is desirable that the corona treatment unit be small and easy to install when in-line. The present invention will be explained in more detail below based on Examples. Example A polyethylene film with a thickness of 50 μm as a web was subjected to corona treatment to a rate of 58 dyne/cm using the apparatus shown in Figure 1, and a radiation-curable adhesive was applied at a rate of 10 g/m ² and the laminated portion was applied with high pressure. An adhesive tape was produced by irradiating and curing ultraviolet rays at a concentration of 2×10 ⁴ J/m ² using a mercury lamp. Comparative Example 1 An adhesive tape was produced in the same manner as in Example, except that a 1000 m long polyethylene film that had been corona treated in advance to a concentration of 58 dyne/cm was used immediately after treatment, and the corona treatment device was not used in the apparatus shown in Figure 1. did. Comparative Example 2 An adhesive tape was produced in the same manner as in Comparative Example 1, except that a polyethylene film that had been left for two periods after corona treatment was used. Table 1 shows the surface tension of the film immediately before the coated area during the production of the above-mentioned adhesive tape, and the results of the anchoring force test of the produced adhesive tape.

【table】

[Table] <Effects of the Invention> As is clear from the above examples, according to the present invention, coating is performed immediately while performing corona treatment, so there is no deterioration over time of the corona treated surface and the front and back sides of the web are coated. This makes it possible to impart good adhesion and releasability to the cured coating agent, and also simplifies the work, which has great industrial value.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of a coating device used in the present invention. 1...web, 2,3...laminate roll,
4... Corona treatment device, 5... Coating machine, 6... Radiation source, 7... Product, 8... Coating liquid.

Claims (1)

[Claims] 1 The web fed out from one end is run in a closed loop so that the leading web and the trailing web form an overlapping part, and the trailing web is coated on the radiation-curable coating agent applied to the surface of the leading web. In a method for manufacturing a coated web, which involves overlapping the back side of the web, irradiating the overlapping portion with radiation to cure the crosslinking, and then peeling off the trailing web, the front surface of the preceding web is peeled off immediately before coating. A method for producing a coated web characterized by performing corona treatment.