JPS60127385A - Release of pressure-sensitive adhesive tape or sheet for masking - Google Patents

Abstract

PURPOSE:To release a pressure-sensitive adhesive tape or sheet from a material to be bonded naturally only by heating, by using a heat-shrinkable substrate and the pressure-sensitive adhesive tape or sheet containing a light release adjustor having bond strength which is reduced during heating for masking. CONSTITUTION:A thermally-releasable pressure-sensitive tape or sheet consisting of heat-shrinkable substrate made of a plastic film such as PE, PP, etc. to be drawn at least one direction and a pressure-sensitive adhesive contaning light release adjustor (e.g., phosphoric ester surface active agent, fatty acid amide, etc.) set on the substrate is applied to part of a material to be coated, coating is carried out, and the heat or sheet is heated and released.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure-sensitive adhesive tape for masking, which is used for temporary surface protection as a mask during painting work, and which can be peeled off extremely easily by heating after achieving this purpose. The present invention relates to a method for peeling a sheet.

When applying paint to various objects, pressure-sensitive adhesive tapes or sheets are often used to mask areas that do not require painting. In other words, if you apply a pressure-sensitive adhesive tape or sheet in advance to areas that do not require painting, apply paint to the entire surface including this tape or sheet, and peel off this tape or sheet after the paint has dried, this The area where the tape or sheet was pasted becomes the non-painted area. By using an adhesive tape or sheet for masking during painting in this way, painting can be done efficiently and the boundary line with the painted area can be clearly drawn.

However, when removing the adhesive tape or sheet 1'fl after the paint has dried, depending on the size and shape of the non-painted area, it may take some time to peel off the edge of the tape or sheet to create a trigger for peeling, or Alternatively, there is a problem that the peeling workability is low, such as having to manually peel the sheets one by one.

Therefore, the inventors conducted extensive studies with the aim of providing a useful peeling method using a masking pressure-sensitive adhesive tape or sheet that can be peeled off from the adherend with good workability after the pasting purpose has been achieved. As a result, when a pressure-sensitive adhesive tape or sheet containing a light release modifier is used for masking during painting, the support is heat-shrinkable and the adhesive strength of the pressure-sensitive adhesive decreases when heated. We also discovered that the sheet naturally peels off from the adherend simply by heating, which greatly improves the peeling efficiency.
This invention has been made.

That is, the present invention provides a heat-shrinkable support made of a plastic film stretched in at least one direction on a part of the surface to be coated, and a pressure-sensitive adhesive containing a light release modifier provided on the support. After pasting a heat-releasable masking pressure-sensitive adhesive tape or sheet consisting of an agent layer as a paint masking, a painting process is performed on the surface to be painted,
The present invention relates to a method for peeling a pressure-sensitive adhesive tape for masking or a sheet, which is characterized in that the sheet is then heated and peeled off.

According to the peeling method of the present invention, a pressure-sensitive adhesive tape or sheet for masking is pasted on a part of the surface to be painted as a mask during painting work, and after achieving the purpose of pasting, this tape or sheet is heated. The adhesive strength of the pressure-sensitive adhesive decreases and the heat shrinkage stress of the support acts on this tape or sheet, so it can be peeled off naturally due to these actions, and it can be peeled off naturally, unlike conventional adhesive tapes or sheets. Compared to manually peeling off one sheet, work efficiency can be greatly improved. In particular, if the above-mentioned heating is performed using the heat generated when the applied paint is heated and dried, the tape or sheet can be peeled off at the same time as the paint film is formed, so there is no need for any special peeling work after the paint film is formed. This is extremely convenient.

The heat-shrinkable support in the masking pressure-sensitive adhesive tape or sheet of the present invention is made of a plastic film that has been stretched in at least one direction, preferably in two directions, to impart heat-shrinkability. As the material for the film, most plastics such as polyethylene, polypropylene, polyvinyl chloride, polyester, polystyrene, etc. can be used, regardless of whether they are crystalline or amorphous.

An unstretched film made of these plastic films is stretched in at least one direction to impart heat shrinkability, and then a pressure-sensitive adhesive containing a light release modifier is applied on this film to a dry adhesive layer thickness of 3. ~I O0/'''' and drying, or apply a pressure-sensitive adhesive containing a light release modifier to the same thickness as above on an unstretched film made of these plastics, dry it, and then apply this film. The pressure-sensitive adhesive tape or sheet for masking of the present invention can be obtained by stretching in at least one direction to impart heat shrinkability.

In addition, which of the above timings to stretch the plastic film is determined by this adhesive tape or sheet #Nln.
The type of plastic film to be used and the drying conditions of the pressure-sensitive adhesive should be adjusted so that the support has heat shrinkability. Determined by consideration. For example, when using films made of amorphous polymers such as polyvinyl chloride and polystyrene, these stretched films tend to shrink due to heat when drying the adhesive, so normally It is preferable to apply the adhesive and dry it before stretching.

The stretching ratio of plastic varies depending on the adhesive strength of the tape or sheet when made into a pressure-sensitive adhesive tape or sheet, the purpose of use, the type of plastic film, etc., but it depends on the heat shrinkage stress of the plastic film in at least one direction due to heat shrinkage. is 100P/20mm width or more, preferably 200y/20m+width or more,
It is set taking into consideration the thickness of the stretched plastic film.

Generally, the stretching ratio may be about 15 to 8 times in at least one direction. The thickness of the support made of the plastic film after stretching is usually about 10 to 300 nm.

When the pressure-sensitive adhesive used in this invention is masking the surface of an adherend, the masking pressure-sensitive adhesive tape or sheet must be applied with an adhesive force that is at least strong enough to prevent the masking pressure-sensitive adhesive tape or sheet from peeling off from the adherend. The adhesive is not particularly limited as long as it can be easily peeled off from the adherend without leaving any adhesive residue as the support shrinks during heating, but it is preferable that the adhesive has a 180° peel adhesive strength by heating during peeling. ”00?/20tx
It is desirable that the width be less than m. Suitable examples include natural rubber pressure-sensitive adhesives using natural rubber as a base polymer or acrylic pressure-sensitive adhesives using an acrylic acid alkyl ester polymer as a base polymer. A small amount of tackifier may be added to these adhesives to increase adhesive strength during masking.
It is also preferable to vulcanize to an extent that does not impair adhesiveness in order to prevent adhesive residue from being peeled off.

The light release modifier used in this invention is added to the above-mentioned pressure-sensitive adhesive, thereby reducing the adhesive force of the adhesive during heat peeling as described above, and facilitating thermal shrinkage of the plastic film due to heating. It facilitates the peeling of the masking pressure-sensitive adhesive from the adherend. Typical examples of such light release modifiers include phosphate ester surfactants and fatty acid amides.

The above-mentioned phosphate ester surfactant is represented by the general formula (Il, (where n is an integer of 2 to 50, R is an alkyl group or an alkylphenyl group having 8 to 30 carbon atoms). Phosphoric acid monoester, phosphoric acid diester, or a mixture of these with a trace amount of triester is used.

In addition, as the fatty acid amide, general formula R'-cONH2
(R' is an alkyl group having 8 to 24 carbon atoms), such as stearic acid amide, palmitic acid amide, ricinoleic acid amide, oxystearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, Examples include lauric acid amide and ethylene bisstearic acid amide. These light release modifiers are usually used in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of the base polymer of the pressure-sensitive adhesive.

A pressure-sensitive adhesive containing the above-mentioned light release modifier is applied to a plastic film before or after stretching and dried. However, when using a polyolefin film such as a polyethylene film or a polypropylene film as the above-mentioned film, pressure-sensitive adhesive is applied. It is desirable to increase the wetting tension of the surface of the support by subjecting the surface to which the adhesive is applied to various commonly used surface treatments such as corona discharge treatment and ultraviolet irradiation treatment. It is necessary to dry the adhesive at a temperature at which the stretched plastic film does not shrink due to heat.

When an adhesive is applied to a film before stretching and dried, the film is subsequently stretched to impart heat shrinkability.

In this invention, after the pressure-sensitive adhesive tape or sheet for masking obtained as described above is adhered to a part of the surface to be painted, a predetermined painting treatment is applied to the surface to be painted.

This coating treatment can be carried out according to a conventional method, and a wide variety of conventionally known organic solvent-based paints, emulsion-based paints, and powder paints can be used.

After the above painting process, the masking pressure sensitive adhesive tape or sheet is peeled off. This peeling is carried out by heating, and usually heating at 100 to 200'C for 1 to 30 minutes is all that is required, and the tape or sheet is thereby naturally peeled off from the adherend.

Note that the above heating peeling can be performed simultaneously with the heating drying process during the painting process. In this case, the tape or sheet can be naturally peeled off at the same time as the coating film is formed, without requiring a heating peeling process after the painting process. Efficiency is further improved. On the other hand, if the necessary thermal energy for peeling cannot be obtained during the heat-drying process of the paint, after the heat-drying process,
Preferably, by locally heating the area where the tape or sheet is attached, more efficient peeling can be achieved than in the past.

By peeling off the masking tape or sheet in this way, the boundary line between the non-painted area and the painted area consisting of the area where the tape or sheet was pasted was clearly drawn.
It is possible to obtain a coated article having the required coating film only at the required locations.

Next, examples for clarifying the above effects of the present invention will be described in comparison with comparative examples. In the following, parts refer to parts by weight.

Example 1 100 parts of natural rubber, 20 parts of phenolic resin, 1 part of sulfur, and both formulas represented by the general formulas (Il and (II), n =2.R:=The thickness of the adhesive layer after drying a natural rubber pressure-sensitive adhesive consisting of 0.1 part of a compound of a phosphoric acid monoester and a phosphoric acid diester having a stearyl group is 10/'' Apply 1o.

A pressure-sensitive adhesive sheet was prepared by drying at °C for 5 minutes.

This adhesive sheet was stretched vertically and horizontally for 1.
It was stretched 5 times at 100°C to obtain a pressure-sensitive adhesive sheet for masking with a thickness of about 48 cm.

The heat shrinkage force of this sheet was measured using the method below, and the results were 180y/20mm in length and 160mm in width. / 20txm wide.

<Heat shrinkage force test> A sample sheet cut into 20 tnm (length) and 20 width (width) is fixed in the vertical and horizontal directions, and the temperature is raised from room temperature to 130'C. The maximum stress applied to the chuck that fixed the sample sheet at this time was expressed as the heat shrinkage force.

At the same time, add 5cm of the above pressure-sensitive adhesive sheet for masking.
Cut it into a size of X5 (1) and make it 10cm
It was attached to the center of a 5Pc-grade bright steel plate with a size of m and a thickness of 1 tone. Next, apply an acrylic emulsion type paint to the entire surface of the steel plate, including the top of this sheet, so that the coating thickness after drying is approximately 0.
．． After coating for 3 runs, the coating was left in a hot air dryer at 130° C. with the coating surface facing downward, and then heated and dried for 30 minutes.

The results of observing the peelability of the adhesive sheet by heating and drying above showed that it naturally peeled off 8 times in 10 paint masking tests, and the remaining two adhesive sheets that did not peel off almost peeled off at the center of the steel plate. The sheet was shrunk in a closed state, and the shrunken sheet could be removed without effort by simply picking it up with fingers.

Example 2 One side of the same polyvinyl chloride film as in Example 1 was coated with 100 parts of a copolymer consisting of 100 parts of butyl acrylate, 15 parts of acrylonitrile, and 5 parts of acrylic acid, 2 parts of the polyincyanate compound, and the resin used in Example 1 above. An acrylic pressure-sensitive adhesive consisting of 0.11 parts of phosphoric acid ester was applied and dried in the same manner as in Example 1 to prepare a pressure-sensitive adhesive sheet. This adhesive sheet was stretched by 1.5 times both lengthwise and widthwise in the same manner as in Example 1 to obtain a pressure-sensitive adhesive sheet for masking having a thickness of 48 units. As a result of measuring the heat shrinkage force of this sheet in the same manner as above, the length was 180y/20m.
It was 160y/20mm wide and 160y/20mm wide.

When this adhesive sheet was attached to a steel plate in the same manner as in Example 1, and paint was applied and dried, it naturally peeled off 8 times in 10 paint masking tests, and the remaining 2 sheets did not peel off. Similarly to Example 1, the adhesive sheet could be removed by simply picking it up with fingers, and the peeling efficiency was extremely high.

Example 3 Natural rubber-based pressure-sensitive adhesive consisting of 100 parts of natural rubber, 20 parts of phenolic resin, 1 part of sulfur, 1 part of stearic acid amide and 1 part of ricinoleic acid amide was applied to one side of the same polyvinyl chloride film as in Example 1. The agent was applied and dried in the same manner as in Example 1 to prepare a pressure-sensitive adhesive sheet. This adhesive sheet was stretched by 1.5 times in the length and width in the same manner as in Example 1 to obtain a pressure-sensitive adhesive sheet for masking having a thickness of 48 μm.

The heat shrinkage force of this sheet was measured in the same manner as described above, and the width was 180y/2o in length and 160mm/20mm in width.

Using this adhesive sheet, we adhered it to a steel plate in the same manner as in Example 1, and then applied paint and dried it. In 10 paint masking tests, it peeled off naturally 7 times, and the remaining 3 sheets that did not peel off. The adhesive sheet could also be easily peeled off as in Example 1.2.

Comparative Example 1 A pressure-sensitive adhesive sheet for masking was obtained in exactly the same manner as in Example 1, except that a phosphate ester as a light release modifier was not included in the natural rubber-based pressure-sensitive adhesive, and this sheet was When the adhesive sheet was adhered to a steel plate in the same manner as in Example 1, and a paint was applied and dried, the adhesive sheet did not peel off in all 10 paint masking tests.

Therefore, an attempt was made to peel off this adhesive sheet manually, but it took time to peel off the edges, and although there was a masking effect, the peeling efficiency was extremely poor compared to Examples 1.2 and 3.

Comparative Example 2 A pressure-sensitive adhesive sheet for masking was obtained in exactly the same manner as in Example 1, except that the acrylic pressure-sensitive adhesive did not contain a phosphate ester as a light release modifier, and this sheet was also used. The adhesive sheet was adhered to a steel plate in the same manner as in Example 2, and then a paint was applied and dried. In the 10 times of the paint masking test, this adhesive sheet did not peel off at all, and although an attempt was made to peel it off, there was no comparison. As in Example 1, the peeling efficiency was extremely poor.

As is clear from the results of Examples 1 to 3 and Comparative Example 1.2 above, according to the method of the present invention, the pressure-sensitive adhesive tape or sheet used for masking in the heating drying process of paint can be peeled off very easily. It turns out that it is a good thing.

Examples 4 to 6 After applying and drying a natural rubber pressure-sensitive adhesive, the stretching ratio was as shown in the table below (except for the change, the same method as in Example 1 was carried out to prepare sheets with different sheet thicknesses and heat shrinkage forces). Pressure-sensitive adhesive sheets for masking seeds were obtained, and the peeling effect of these sheets after coating masking on a 5PC-grade bright steel plate was examined using the same method as described above.The results are shown in the table below.

In addition, the number of heat-peeled pieces in the table shows the number of times they naturally peeled off during the heat-drying process in 10 paint masking tests, and most of the pieces that did not peel off shrunk while still being peeled off. Because of this, it was easy to remove by just picking it up with your fingers.

Example 7 Instead of a polyvinyl chloride film with a thickness of 100P, a polyvinyl chloride film with a thickness of 2
A pressure-sensitive material for masking with a thickness of 93 μm was prepared in the same manner as in Example 1 using a 00 pn polyvinyl chloride film and using the same conditions as in Example 1, such as the type of pressure-sensitive adhesive and the stretching ratio. An adhesive sheet was obtained.

The heating shrinkage force of this sheet is 34.0 y/20mm in length.
The width was 310 y/20 mm, and in 10 coating masking tests on the same steel plate as in Example 1, all of the coatings peeled off naturally within 10 minutes.

Comparative Example 3 A pressure-sensitive adhesive sheet for masking was obtained in exactly the same manner as in Example 7, except that the phosphate ester as a light release modifier was not included in the natural rubber adhesive, and this sheet was used to conduct the test. When the coating masking test was carried out on a steel plate 10 times in the same manner as in Example 1, this adhesive sheet did not peel off at all in all 10 times, and although attempts were made to peel it off, the work efficiency was extremely poor.

As is clear from the results of Examples 4 to 7 and Comparative Example 3, according to the method of the present invention, the heat shrinkage force of the pressure-sensitive adhesive sealing sheet for masking to which a light release modifier has been added is determined by the stretching ratio and before stretching. By appropriately adjusting settings such as the thickness, good peeling effects similar to those of Examples 1 to 3 can be obtained,
In particular, it can be seen that by setting the heat shrinkage force to 200 f/20 gm width or more, all the adhesive sheets are peeled off naturally, and no special peeling work is required at all, which is advantageous.

Patent applicant: Nitto Electric Industry Co., Ltd.

Claims (2)

[Claims] (1) A heat-shrinkable support made of a plastic film stretched in at least one direction on a part of the surface to be painted, and a pressure-sensitive adhesive layer containing a light release modifier provided on the support. A thermally releasable pressure-sensitive adhesive tape or sheet for masking is applied as a paint masking, and then a coating treatment is applied to the surface to be painted, and then the sheet is heated and peeled off. How to peel off pressure-sensitive adhesive tapes or sheets for masking. (2) The method for peeling a pressure-sensitive adhesive tape or sheet for masking according to claim (1), wherein the light release modifier comprises a phosphate ester surfactant or a fatty acid amide.