JPH0126389B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a protective film or adhesive tape for temporarily protecting the surfaces of decorative boards, glass boards, precious wood boards, acrylic boards, metal boards, etc., or films or sheets with temporary adhesive properties thereof, and particularly relates to The present invention relates to a pressure-sensitive adhesive film that has suitable adhesive strength at room temperature. Conventionally, in manufacturing pressure-sensitive adhesive films, a pressure-sensitive adhesive composition dissolved in a suitable solvent is coated onto a base film that has been subjected to a suitable undercoating process, and then the solvent is removed in a drying process. There were many methods used to remove the . Such solvent coating methods require a large amount of solvent to be removed in the drying process, require a long drying zone and solvent recovery equipment, and from an occupational health perspective, there are concerns about solvent poisoning, and fire prevention and This method had many disadvantages in terms of production costs and could not be considered a desirable method. As an alternative to solvent coating methods, there has been a tendency to adopt the so-called hot-melt coating method, which is a non-solvent coating method. Moreover, for polyolefin base materials, the adhesive force between the base material and the adhesive is weak, and preliminary treatment such as undercoating is required, which has many disadvantages. On the other hand, as a method to solve this drawback, the polymer for the base material layer, such as polyethylene or polypropylene, is extruded in a molten state to form a thin film, and at the same time, the adhesive component is also extruded, and the two are laminated together while both are in the molten state. There is a method for producing an adhesive film. However, in such a coextrusion method, from the viewpoint of extrusion processability, film formability, and pelletization of the adhesive layer resin, conventionally, the adhesive layer is made of ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, etc. The use of ethylene-based copolymers alone, such as polymers, or mixed resins containing a small amount of tackifier has been used. However, in this case, the adhesive strength at room temperature is weak,
In order to obtain a suitable adhesion force, it is necessary to heat-seal the adhesive to the surface of the adherend. In addition, styrene-based diene block copolymers such as styrene-butadiene copolymer and styrene-isoprene copolymer are usually blended with tackifiers, oils, etc., and are used in the production of pressure-sensitive adhesive films. However, it is difficult to pelletize the mixed resin and the melt viscosity is low, making it impossible to manufacture by coextrusion with the base layer resin, and it is not possible to coat the base film using a hot melt coating method. Ta. Based on these circumstances, the present inventor has conducted various studies on adhesive layer resin compositions that have suitable adhesive strength at room temperature and can be co-extruded with the base layer resin, and have developed a resin compound for the adhesive layer. With ethylene copolymers and tackifiers such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic ester copolymer, ethylene-acrylic ester-vinyl acetate terpolymer, etc. By using a resin compound for an adhesive layer which is made by blending a styrene-olefin block copolymer such as a styrene-butadiene block copolymer or a styrene-isoprene block copolymer with a composition containing a stabilizer, polyethylene or We have discovered that it is possible to obtain a pressure-sensitive adhesive film that can be coextruded with a base layer resin made of polypropylene and has suitable adhesive strength at room temperature, and based on this knowledge, we have completed the present invention. be. That is, the gist of the present invention is to add a styrene-butadiene block copolymer or a styrene-isoprene block copolymer to a composition containing a base layer resin made of polyethylene or polypropylene, an ethylene copolymer, a tackifier, and a stabilizer. This method of producing a pressure-sensitive adhesive film is characterized by coextruding a resin compound for an adhesive layer, which is made by blending a styrene-diene block copolymer such as a polymer. Hereinafter, the present invention will be explained in detail. A styrene-diene such as a styrene-butadiene block copolymer or a styrene-isoprene block copolymer is added to a composition containing a base layer resin made of polyethylene or polypropylene, an ethylene copolymer, a tackifier, and a stabilizer. A pressure-sensitive adhesive film having an adhesive layer laminated on a base layer is obtained by coextruding a resin compound for an adhesive layer containing a block copolymer. Therefore, in the manufacturing method of the present invention, polyethylene or polypropylene manufactured by a known manufacturing method can be used as the resin for the base material layer. For example, polyethylene can be obtained by any of the high pressure method, medium pressure method, and low pressure method. You can also use things. Next, the ethylene copolymers that are a component of the adhesive layer resin compound include ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic ester copolymers, and ethylene-acrylic ester-acetic acid copolymers. At least one resin selected from vinyl terpolymers and saponified ethylene-vinyl acetate copolymers is used, but these ethylene copolymers have a low ethylene content.
Preferably, the content is 50wt% or more. If the ethylene content is less than 50 wt%, sufficient interlayer adhesion with the base material layer cannot be obtained, and the composition mixed with the styrene-diene block copolymer and tackifier cannot be pelletized. This is because it becomes difficult. Next, as the styrene-diene block copolymer which is a component of the adhesive layer resin compound, a styrene-butadiene block copolymer or a styrene-isoprene block copolymer can be used. The amount of this styrene-diene block copolymer is 10 to 100 parts by weight, preferably 20 to 80 parts by weight, per 100 parts by weight of the composition containing the ethylene copolymer, tackifier, and stabilizer. Parts by weight. Therefore, the amount of styrene-diene block copolymer
If the amount is less than 10 parts by weight, sufficient adhesive strength will not be obtained at room temperature, while if it exceeds 100 parts by weight, it will be difficult to pelletize the resin compound for the adhesive layer and it will be difficult to form a film. Next, the tackifiers that are compounded components of the resin compound for the adhesive layer include aliphatic, aromatic, alicyclic petroleum resins, α-vinene, β-vinene, dipentene, terpene resins, and rosin-modified rosin. Resin can be used. The amount of the tackifier used varies depending on the type of tackifier and the type of substrate to which it is adhered, but it is 10 to 100 parts by weight, preferably 20 to 70 parts by weight, based on 100 parts by weight of the ethylene copolymer. Mix within the range. However, if the amount of tackifier added is less than 10 parts by weight, sufficient adhesive strength will not be obtained at room temperature.
On the other hand, if it exceeds 100 parts by weight, the fluidity of the mixed resin will be too high, making it difficult to form a film. Next, the stabilizers that are compounded components of the resin compound for the adhesive layer include organic tin, heat stabilizers such as metal soap, BHT,
Antioxidants such as BHA are used. This is due to deterioration of the tackifier due to heating during film formation, styrene
It is used as a compounding component of a resin compound for an adhesive layer in order to prevent oxidative deterioration of the diene block copolymer. Next, the thickness of the pressure-sensitive adhesive film obtained by the production method of the present invention is determined by the required strength (tensile, tear,
Although it varies depending on the scratch resistance, etc.), the total thickness is 30~
220μ is appropriate, of which the thickness of the base material layer is 20μ
~180μ, and the appropriate thickness of the adhesive layer is 10~40μ. Next, the manufacturing method of the present invention can be carried out by either a multilayer inflation method or a multilayer T-die method. Next, even if the film of the product obtained by the manufacturing method of the present invention is wound into a roll, the adhesive force between the base layer and the adhesive layer is weak, and it is possible to easily unroll it, but it is difficult to use release paper. You can also wind it up by sandwiching it. As detailed above, according to the manufacturing method of the present invention, a pressure-sensitive adhesive film that exhibits sufficient adhesion at room temperature and has extremely high interlayer adhesion can be easily formed in one step by coextrusion. Obtainable. In addition, since no solvents are used in the production of pressure-sensitive adhesive films, it is highly safe and does not require large equipment for drying or solvent recovery, and there is no risk of fire or pollution. . Next, the manufacturing method of the present invention will be described in more detail with reference to Examples and Comparative Examples. Example 1 Polyethylene with a density of 0.923 and a melting index of 2.3 was used as the base layer, and 100 parts by weight of various ethylene copolymers and tackifier (2:1) were used as the adhesive layer.
30 various styrene-diene block copolymers
2 parts by weight of a mixed resin containing 0.5 parts by weight of BHT.
A film was formed using a layer coextrusion inflation method. The thickness of the base material layer of this film was 40μ, and the thickness of the adhesive layer was 20μ. The adhesive layer resins used are as shown in Table 1. Comparative Example 1 A film was formed in the same manner as in Example 1 without blending the styrene-diene block copolymer. The films of Example 1 and Comparative Example 1 were laminated to a substrate (SUS304 steel plate), based on JIS C2107.
The 180° peel strength was measured. The results are shown in Table 1. As shown in Table 1, it is remarkable that a film having suitable adhesive strength at room temperature can be obtained by blending a styrene-diene block copolymer.

【table】

[Table] Example 2 Polyethylene with a density of 0.923 and melting index of 2.3 as the base layer resin, ethylene-vinyl acetate copolymer (vinyl acetate content 16%) and rosin-based tackifier (2:1) as the adhesive layer resin 10 to 100 parts by weight of styrene-isoprene block copolymer per 100 parts by weight,
A film was formed using a two-layer coextrusion inflation method using a mixed resin containing 0.5 parts by weight of BHT. Comparative Example 2 A film was formed in the same manner as in Example 2 except that the amount of the styrene-isoprene block copolymer was changed to 5,150 parts by weight. The films of Example 2 and Comparative Example 2 (although some films could not be formed) were laminated to an adherend substrate (SUS304 steel plate), and the 180° peel strength based on JIS C2107 was measured.
The results are shown in Table 2. As shown in Table 2, if the amount of the styrene-diene block copolymer is 10 parts by weight or less per 100 parts by weight of the composition containing the ethylene copolymer and the tackifier, sufficient adhesion is not achieved at room temperature. On the other hand, if the amount exceeds 100 parts by weight, it will be difficult to pelletize the mixed resin, and even if pellets are formed, the perforated bulb will become unstable during film formation, making film formation impossible. This is not desirable.

【table】

Claims (1)

[Scope of Claims] 1. A composition containing a base layer resin made of polyethylene or polypropylene, an ethylene copolymer, a tackifier, and a stabilizer, and a styrene-butadiene block copolymer or a styrene-isoprene block copolymer. A method for producing a pressure-sensitive adhesive film, which comprises coextruding a resin compound for an adhesive layer, which is a mixture of a styrene-diene block copolymer such as a polymer. 2 Composition containing ethylene copolymer, tackifier, and stabilizer as resin compound for adhesive layer
The method for producing a pressure-sensitive adhesive film according to claim 1, characterized in that a resin compound is used in which the blending ratio of the styrene-diene block copolymer is 10 to 100 parts by weight per 100 parts by weight. 3. The pressure-sensitive adhesive film according to claim 1 or 2, wherein a resin compound containing an ethylene copolymer with an ethylene content of 50% by weight or more is used as the resin compound for the adhesive layer. manufacturing method.