JP2549884B2 - Method for manufacturing urethane-based adhesive tape and sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a urethane-based adhesive tape and sheet.

Conventional technology and its problems Polyurethane pressure-sensitive adhesives do not contain solvents such as organic solvents and water, so they are more problematic in terms of safety and health and pollution than conventional pressure-sensitive adhesives obtained by solution polymerization or emulsion polymerization. It has excellent removability because it can be peeled off without adhesive residue on the adherend surface, and when dust or dust adheres to the adhesive surface, it can be easily removed by washing with water and repeated reuse becomes possible. It has excellent features.

However, when such a polyurethane pressure-sensitive adhesive is produced, the reaction between the polyol and the polyisocyanate requires a long time, and when the reaction is accelerated by heating, for example, a time of 5 minutes or more at 100 to 120 ° C. In this heat treatment, the adhesiveness of the obtained polyurethane pressure-sensitive adhesive varies depending on the heat treatment condition, and it is difficult to obtain a pressure-sensitive adhesive having a constant adhesive performance.

For this reason, in order to obtain a urethane-based pressure-sensitive adhesive in the form of a sheet to date, a mixture of a polyol and a polyisocyanate is poured into a frame provided on a release plate, and it takes a long time to form the sheet-like form. At present, the method is adopted (for example, see Japanese Patent Laid-Open No. 62-106987). However, this method has drawbacks such as very poor productivity and inability to manufacture a long sheet.

Means for Solving the Problems The present inventor has carried out earnest research to develop a method for producing a urethane-based pressure-sensitive adhesive tape and sheet in the form of a long product with high efficiency in a production line, and as a result, Finally, the present invention has been completed.

That is, in the present invention, a mixture of a polyol and a prepolymer having a terminal isocyanate group obtained by reacting a polyol and a polyisocyanate is poured into a gap between the mesh-like substances placed on a release paper or a release film. Then, the present invention relates to a method for producing a urethane-based pressure-sensitive adhesive tape and sheet, which comprises laminating a release film having elasticity on the mesh-shaped substance and winding the roll-shaped release film.

As the release paper and release film used in the present invention, conventionally known release papers can be widely used. Specific examples of the release paper include kraft paper, white fine paper, roll paper, semi-glassine paper, and the like, and silicone direct coating, and those obtained by laminating a polyethylene thin film on the base paper and then applying the silicone coating. Specific examples of the release film include polyester, polypropylene, polyethylene film coated with silicone and the like.

The mesh-like substance used in the present invention has a large number of small gaps, and can be widely used as long as it is a substance that can be wound, for example, polyethylene, polypropylene nets, cloth such as kansai, Examples include non-woven fabrics. The gap between the substances is usually about 5 to 500 mesh, preferably about 40 to 200 mesh, and the thickness is 0.01.
It is about 2 mm, preferably 0.05 to 0.5 mm.

As the polyol used in the present invention, conventionally known ones can be widely used as long as they have two or more hydroxyl groups at the molecular ends and a molecular weight of about 1000 to 1500, for example, polyoxyethylene glycol, polyoxypropylene glycol. Polyether diols such as polyoxyethylene-polyoxypropylene glycol, polyoxytrimethylene glycol, polyoxytetramethylene glycol, polyoxybutylene glycol and mixtures thereof,
Polyoxypropylene triols, polyether triols such as polyoxyethylene-polyoxypropylene triols, polyethers such as trimethylolpropane, glycerin, pentaerythritol copolymerized in the molecule of the above polyether diols, and polyethers such as mixtures thereof. A polyol etc. can be mentioned. Among these, polyoxypropylene glycol is particularly suitable.

The prepolymer used in the present invention is obtained by reacting a polyol and a polyisocyanate, and has an isocyanate group at the terminal. Here, as the polyol, those described above can be widely used. As the polyisocyanate, conventionally known ones can be widely used, for example, 2,4-toluylene diisocyanate and 2,6-toluylene diisocyanate or a mixture thereof, crude toluylene diisocyanate, 4,4'-diphenylmethane diisocyanate, Aromatic diisocyanates such as 2,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, 1,5-naphthylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, isopropyl diisocyanate Aliphatic or alicyclic diisocyanates such as lidene bis (cyclohexyl isocyanate) and xylylene diisocyanate, dimers, trimers and carbodiimide modified products thereof can be mentioned. The prepolymer of the present invention can be easily produced from the above polyol and polyisocyanate according to a conventional method.

According to the method of the present invention, first, a release paper or a release film (hereinafter, this may be referred to as "first release film")
A mixture of the polyol and the prepolymer is poured into the gap between the mesh-like substances placed on the top. The mixing ratio of the polyol and the prepolymer is not particularly limited, but it is preferable to mix both so that the NCO / OH ratio is usually about 0.5 to 2, preferably about 0.7 to 1.2.
If the NCO / OH ratio is larger than the above range, it tends to cause a problem that the adhesiveness is lowered, which is not preferable.
On the other hand, if the NCO / OH ratio is smaller than the above range, the non-transferability tends to be impaired, which is a disadvantage.

As a means for pouring the mixture of the polyol and the prepolymer into the space of the mesh-like substance, a conventionally known method can be widely adopted, and for example, the mixture may be applied to the mesh-like substance by a roll coater, a comma coater, a spray or the like. .

In the present invention, next, a release film having stretchability on the mesh-like substance (hereinafter referred to as “second release film”)
Sometimes it is said), and then roll it up. This is to make the thickness of the obtained urethane-based adhesive tape or sheet constant and to make the surface smooth. As the stretchable release film used here, one having a tensile strength of 300 kg / cm or less (preferably 150 kg / cm or less) and an elongation of 50% or more (preferably 100% or more) is suitable. Examples include release-treated nylon film, soft vinyl chloride film, vinylidene chloride film, polyethylene film, and various composite films (specifically, nylon / polyethylene, nylon / Ever, polyethylene / polypropylene lami film, etc.). . Of these, low density polyethylene film is particularly preferable. The thickness of such a stretchable release film is usually about 10 to 100 µ, preferably about 20 to 80 µ. When a release film that does not have elasticity is used, distortion occurs due to the difference in winding diameter between the first release film and the second release film when wound on a roll, and the resulting urethane-based adhesive There is a drawback that the wrinkles and uneven thickness of the tape and sheet cannot be avoided.

The tape or sheet wound into a roll as described above is left to stand at room temperature or in a greenhouse as it is, and unreacted polyol and prepolymer existing in the gaps of the mesh-like substance are continuously present. The urethane reaction is continued and then terminated to obtain the desired urethane-based adhesive film or sheet.

EFFECTS OF THE INVENTION According to the method of the present invention, a urethane-based adhesive film and sheet can be efficiently produced in the form of a long product.

Examples The present invention will be further clarified below with reference to Examples and Comparative Examples.

Example 1 A non-woven fabric [Spunbond 90403 WSO, thickness 220μ, manufactured by Unitika Ltd.] was placed on a release paper [70K EPS cream, manufactured by Honshu Paper Co., Ltd.], and polypropylene glycol [Bond UH100A, average molecular weight] was placed thereon. About 1500, Unishi Co., Ltd.
Made] and terminal isocyanate prepolymer [Bond UH10
0B, manufactured by Unishi Co., Ltd.] with an equivalent mixture (NCO / OH = 0.8) by a roll spreader. Thereafter, a 40 μm release low-density polyethylene film (manufactured by Fujimori Industry Co., Ltd.) was laminated with a laminating roll and then wound on a 3-inch paper tube. After winding, it was allowed to stand at room temperature for 24 hours to obtain an adhesive sheet. The obtained sheet was a good sheet having a thickness of 250 to 270μ.

Example 2 A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the mixing ratio of polypropylene glycol and prepolymer in Example 1 was changed to NCO / OH = 1.0. The obtained sheet was a good sheet having a thickness of 250 to 270μ.

Example 3 A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that Spunbond 90173 WSO [thickness 110 μm, manufactured by Unitika Ltd.] was used as the nonwoven fabric. The resulting sheet has a thickness of 130-1
It was a good sheet of 50μ.

Comparative Example 1 Release Paper EPS Instead of Release Low Density Polyethylene Film
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that cream was used, but wrinkles were generated over the entire surface during winding, and only a non-uniform sheet was obtained.

For each pressure-sensitive adhesive sheet obtained in the above example, the adhesive strength,
Holding power and ball tack were measured according to the methods described below. The results are shown in Table 1 below.

Adhesive strength: 180 times after 7 days after applying the adhesive sheet to each adherend
The peel adhesion was measured. Pulling speed: 300mm / min Holding power: Adhesive sheet is attached to stainless steel plate, and after 7 days
A shear load of 1 kg was applied, and the time until falling was measured. Adhesion area: 2.5 × 2.5 cm ² Ball tack: Measured by J. Dow method.

[Brief description of drawings]

FIG. 1 is a sectional view of a urethane-based pressure-sensitive adhesive sheet obtained by the method of the present invention. FIG. 2 is a sectional view of a urethane-based pressure-sensitive adhesive sheet wound according to the method of the present invention. 1: First release film, 2: Mesh material, 3: Polyurethane, 4: Second release film

Claims (1)

(57) [Claims] 1. A mixture of a polyol and a prepolymer having a terminal isocyanate group obtained by reacting a polyol and a polyisocyanate is poured into a space between the mesh-shaped substances placed on a release paper or a release film,
Next, a method for producing a urethane-based pressure-sensitive adhesive tape and sheet, which comprises laminating a release film having elasticity on the mesh-shaped substance and winding the roll-shaped release film.