JPH04226183A - Pressure-sensitive adhesive tape or sheet and its surface treatment - Google Patents

Abstract

PURPOSE:To provide a pressure-sensitive adhesive tape or sheet having good rewindability (developing power), retaining good releasability for a long time and not adversely affecting the quality without using any release agent by a simple process. CONSTITUTION:A pressure-sensitive adhesive tape or sheet, wherein the rear side comprising a polyolefinic resin as a base on one side of which a pressure- sensitive adhesive layer is formed is surface-treated by applying a shearing force thereto.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an adhesive tape or sheet in which an adhesive layer is laminated on one side of a base layer made of polyolefin resin, and a surface treatment method for the same, and more particularly relates to a method for unwinding the tape or sheet when it is made into a roll. The present invention relates to an adhesive tape or sheet having good properties (developing strength) and a surface treatment method thereof.

0002

[Prior Art] Adhesive tapes or sheets have a base layer made of polyolefin resin and an adhesive layer laminated on one side.
It is publicly known. The product form of this adhesive tape and the like is generally a rolled body obtained by winding these tapes into a coil shape.

0003

[Problems to be Solved by the Invention] By the way, in a rolled body of adhesive tape, etc., the adhesive layer of the outer adhesive tape and the back surface of the base material of the inner adhesive tape have a relatively strong adhesive force. The adhesive tape sticks tightly to the adhesive tape, and as it is, it is difficult to peel it off when unwinding the adhesive tape or the like from the roll. Therefore, when unwinding adhesive tape etc. from the rolled body, it is possible to easily unwind the adhesive tape etc. inside the roll without causing any migration of the adhesive tape etc. to the back side of the base material, blocking, or layer cracking of the base material. As such, a so-called mold release treatment is usually performed on the back side of the base material. Conventionally, this mold release treatment is often carried out by applying a mold release agent to the back surface of the base material in advance.

[0004] However, it is extremely difficult to provide a mold release agent with the contradictory properties of firmly adhering to the back surface of the substrate and making it easy to separate from the adhesive layer. Therefore, it is necessary to take measures such as using a special mold release agent, applying an undercoat to the back surface of the base material, or subjecting the back surface of the base material to corona discharge treatment.

As a mold release agent, a linear alkyl group-containing polymer (for example, polyvinyl ester allyl carbamate) is used.
, silicone polymers, perfluoro polymers, etc. are used. However, in this method of using a mold release agent, the material cost increases by the amount of the mold release agent, and a complicated mold release agent application process is required, which increases production costs and further reduces the yield. Even in the case of adhesive tape rolls, there was a quality problem in that the release agent migrated to the adhesive layer, resulting in a decrease in adhesive strength.

[0006] Regarding surface protection films, Japanese Patent Application Laid-Open No. 103975/1983 proposes a method in which a base material and an adhesive layer are simultaneously formed and laminated by a coextrusion method, and the process is simplified. Simplification and improvement of adhesion between the base material and the adhesive layer are realized. However, even in the case of the coextrusion method, in order to obtain good unwinding properties, it is still necessary to perform mold release treatment on the back surface of the base material, but it is necessary to perform mold release treatment on the back surface of the base material in advance. The problem is even more serious in that it is not possible and there are time constraints on the mold release process.

[0007] The present invention was made in view of the above-mentioned circumstances, and its purpose is to
Our objective is to provide an adhesive tape or sheet that has good unwinding properties (unrolling force) through a simple process, maintains good releasability over a long period of time, and does not have any negative effects on quality. .

[0008]

[Means for Solving the Problems] As a result of extensive research in order to overcome the problems of the above-mentioned prior art, the present inventors have discovered that the surface of the polyolefin resin of the base material is coated with, for example, a solid material. By creating sliding friction due to contact and applying shearing force, the fine shape and/or crystal morphology of the surface changes, and as a result, the adhesive tape or sheet with the surface treated surface as the back side is rolled up. If
It was found that the spreading force was significantly improved, and that there was no change over time in the spreading force or the initial adhesive force of the adhesive layer.

The present invention has been completed based on these findings. That is, the adhesive tape or sheet according to the present invention is an adhesive tape or sheet in which an adhesive layer is laminated on one side of a base layer made of polyolefin resin, optionally with an intermediate layer interposed therebetween, in which the back side of the base layer is laminated. The surface has been processed by applying shearing force.

[0010] In the adhesive tape or sheet (hereinafter abbreviated as adhesive sheet) in the present invention, an intermediate layer may be provided between the base layer and the adhesive layer, and materials for the intermediate layer include: Kraft paper, cloth, synthetic resin film, etc., which are conventionally used as base materials for adhesive sheets, can be suitably used. These intermediate layers constitute a base material together with a base material layer made of polyolefin resin. Further, for the intermediate layer, in order to improve the interlayer adhesive strength between the base layer and the adhesive layer, a material that is compatible with both the base layer and the adhesive layer can be selected.

In the present invention, polyolefin resins constituting the base layer include polyethylene, polypropylene,
Examples include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and mixtures thereof. The polyolefin resin film may be unstretched, uniaxially or multiaxially stretched.

The material forming the adhesive layer in the present invention is not particularly limited, and includes rubber-based (including thermoplastic elastomer), acrylic-based, and silicone-based adhesives, and ethylene-vinyl acetate copolymer adhesives. Agents etc. are adopted. The composition of these pressure-sensitive adhesives is usually an elastic body mixed with a tackifying resin, a softener, a filler, an anti-aging agent, etc., as appropriate.

[0013] Antioxidants, ultraviolet absorbers, light stabilizers, pigments, etc. may be added to the polyolefin resin and adhesive used as the base material in the present invention, if necessary. The thickness of the base material and the adhesive layer can be set appropriately depending on the purpose of use, but the former is usually about 10 to 500 μm, and the latter is usually about 5 to 100 μm.

[0014] The time at which the back surface of the base material is subjected to shearing force is not particularly limited, but it is necessary to perform the surface treatment before winding up the pressure-sensitive adhesive sheet into a roll. Considering productivity and the like, it is preferable to perform this on the base material alone before forming the adhesive layer on the base material, or after forming the adhesive layer and before winding up the adhesive sheet. In particular, when using a coextrusion method, the latter method is preferred.

The method of applying shearing force to the back surface of the substrate is not particularly limited, but for example, the surface of the substrate may be physically rubbed with a solid substance to shear parallel or perpendicular to the flow direction of the substrate. One example is a method of imparting power.

[0016] Since the process of manufacturing the adhesive sheet usually includes a continuous winding process in which the adhesive sheet is passed through a series of rolls, it is most preferable to carry out the process during this process. As the solid substance, an endless band or roll-shaped solid substance (hereinafter simply referred to as roll) made of fibers or fiber moldings held by a roll-shaped presser foot is used, and the presser foot or roll is rotated in reverse or forward rotation. Alternatively, the adhesive sheet may be brought into contact with the adhesive sheet in a fixed (stopped) state. It is preferable that the flow speed (line speed) of the adhesive sheet is 200 m/min or less, and the circumferential speed (roll speed) of the endless strip or roll is 500 m/min or less.

[0017] The material of the roll is not particularly limited, and for example, a metal roll with fibers such as gauze or cloth or a fiber molded product wrapped around the surface, or a surface layer made of paper, rubber, or synthetic resin laminated. The roller is made of stainless steel or metal with a plated surface, and the coefficient of sliding friction between the surface layer of the roll and the base layer made of polyolefin resin is 0.3 to 0.9. Can be mentioned.

[0018] The shape of the roll does not necessarily have to be cylindrical, and when used in a fixed manner, it may have a semi-cylindrical shape, for example, without protrusions or the like on the part where the back side of the base material of the adhesive sheet comes into contact. Any shape is sufficient as long as it is slidable.

[0019] Instead of a roll, a brush or cloth or the like may be brought into pressure contact with the back surface of the base material of the adhesive sheet. For example, as shown in FIG. 5, the cloth 16 may be pressed against the back surface of the base material of the adhesive sheet 1 using a press roll 10.

[0020] A plurality of means may be used in combination to apply shearing force to the back surface of the substrate. In the present invention, the reason why a peeling effect (developing force improvement effect) is imparted to the back surface of the base layer by applying shearing force to the back surface can be estimated as follows.

[0021] Normally, the base material is manufactured by using a polyolefin resin as a material, using an extruder, an inflation method or a T
This is done by extrusion molding using a die method. At this time, as the molten resin extruded into a tube or sheet is cooled, crystals are formed on the surface of the base material, and the parts that are crystallized and those that are not. It is generally known that parts can be formed. The proportion of the crystallized portion can be expressed as the degree of crystallinity. It is known from a report by Komoto et al. that when shearing force is applied to the surface of polyethylene or polypropylene, the crystallographic morphology of the surface changes (Wear, 75
(1982) 173-182).

By the way, when the unwinding force (unfolding force) of the roll of adhesive sheet is large, for example, the unfolding force is 1000 g.
f/50 mm (measured at an unwinding speed of 30 m/min), when we observed the surface of the base material layer after unwinding, we found that the surface morphology was larger than that immediately after cooling. It was confirmed that this has changed. This change in morphology is very similar to that when shearing force is applied to the surface of the base layer.

[0023] One of the reasons why the rolling body has such a large unfolding force is that a force is required to change the shape of the surface of the base layer when unwinding. By applying a shearing force to the surface of the base material layer and changing the surface morphology in advance, it can be assumed that the force necessary for the change is not required, and that the developing force is reduced as a result.

The shear force applied to the back side of the substrate is typically
The polyolefin resin film should be kept within a range that does not cause deformation such as neck-in. In surface processing of the base material, the amount of work done by shearing force is 10 J or more. If it is less than 10 J, the reduction in the developing force is insufficient, and the developing force may increase due to changes in temperature and time.

When shearing force is applied to the back surface of the base material layer by, for example, contacting the surface with a roll wrapped with nylon cloth, streaks may be formed in parallel to the flow direction (longitudinal direction). In this case, the interval between parallel stripes is usually about 5 to 20 μm, preferably about 7 to 15 μm.

When shearing force is applied to the back surface of the base layer of the adhesive sheet using a roll, the shearing force is adjusted by the tension applied to the adhesive sheet. The sliding friction force due to the drag force between the roll and the adhesive sheet that occurs along with the tension becomes a shearing force. However, in general, if the tension applied to the adhesive sheet is too large, the sheet will be deformed. Therefore, 1 to 50 kg/kg of
By applying a gas flow of cm2, generally an air flow, in addition to the sliding friction force caused by tension and rotational force, it is possible to add a sliding friction force due to gas pressure, without deforming the adhesive sheet. It is possible to obtain shearing force. If the air pressure is less than 1 kg/cm2, the resulting sliding friction force will be too small, and if it exceeds 50 kg/cm2, the sheet will be deformed. Preferably 3 to 20 kg/cm2
, more preferably 5 to 15 kg/cm2.

[0027]

[Function] The adhesive tape or sheet of the present invention has a back surface made of polyolefin resin as a base material that has been surface-treated by applying shearing force.
Alternatively, by changing in advance the crystal form etc. generated on the surface of the base material during the cooling process of the extruded molten polyolefin resin, the form of the base material surface and/or crystal form etc. required at the time of unwinding can be changed. It can be assumed that no force is required and the deployment force becomes lighter as a result.

[0028]

EXAMPLES A specific method and apparatus for applying shearing force to the back surface of a substrate will be explained with reference to FIGS. 1 and 2.

FIG. 1 is an explanatory diagram showing an embodiment in which shearing force is applied to the back surface of the base material of the adhesive sheet. Reference numeral 1 denotes an adhesive sheet in which an adhesive layer is formed on one side of a base material made of a polyolefin resin film, and the direction of the arrow (upper surface) indicates the back surface of the base material. The adhesive sheet 1 created in the previous step is rolled up into a coil shape to form a rolled body, but at the stage before that,
Go through a series of roles. That is, by contacting the counter-rotating metal roll 5 disposed on the roll 4 through the guide roll 2, sliding friction is generated between the back surface of the base material and the roll 5, so that the back surface of the base material Apply shear force to. Rolls 3 and 7 are arranged before and after the roll 5 to apply tension to the adhesive sheet 1. The surface-treated adhesive sheet 1 is passed between pinch rolls 8 and 9 to form a rolled body.

[0030] The roll 5 may be fixed (stopped) or may be rotated forward in the same direction as the flow direction of the adhesive sheet. In that case, the roll speed is higher than the normal line speed. Make it faster.

FIG. 2 is an explanatory diagram showing another embodiment. The adhesive sheet 1 is passed between pinch rolls 21 and 22, and is brought into contact with a roll 24 rotating in reverse (or forward) while being applied with tension by left and right turn rolls 23 and 25.
Sliding friction is generated between the back surface of the base material of the adhesive sheet 1 and the surface of the roll 24. Next, it is passed between pinch rolls 26 and 27 to form a rolled body.

The pinch rolls 21 and 22 are not necessarily provided, but when the roll 24 is rotated in the opposite direction,
Because frictional force is applied in the opposite direction to the flow direction of the adhesive sheet 1,
It is preferable to provide this because the pressure-sensitive adhesive sheet 1 may become loose and it becomes difficult to apply the desired tension. Further, it is preferable that the speed at which the adhesive sheet 1 is fed out by the pinch rolls 21 and 22 is slower than the actual line speed so that tension is applied to the adhesive sheet 1. Alternatively, a dancer roll may be used in which a constant tension is applied to the adhesive sheet 1.

The turn rolls 23 and 25 are vertically movable in parallel to adjust the tension applied to the adhesive sheet 1 or the contact area between the roll 24 and the back surface of the base material of the adhesive sheet 1. The roll 24 may be made of metal, or may have a layer of fiber or fiber molding, paper, rubber, synthetic resin film, etc. on its surface.

Reference numeral 28 denotes a gas outlet for air, etc., which is provided at the contact area between the back surface of the base material and the roll, and has a gas outlet of 1 to 50 k, as desired.
By applying a gas flow of g/cm2, it is possible to add a sliding frictional force caused by gas pressure in addition to the sliding frictional force caused by tension and rotational force.

FIG. 3 shows an example of a buff roll in which fibers or fiber molded bodies 6 are wound around the surface of a metal roll 15, and the surface layer of the roll 15 is made of metal, paper, rubber, synthetic resin film, etc. Good too.

FIG. 4 shows a unit buff body, in which the cloth is cut to a certain width at an angle of 45 degrees to the fiber direction and joined at the ends.
It is wound around the metal plate 51 in a cylindrical shape to form a disk shape. A buff roll is constructed by arranging a plurality of unit buff bodies, fitting a shaft into a shaft hole 52, and fixing with a metal fitting. Compared to metal rolls, buff rolls using unit buff bodies are
It has the advantage of being able to absorb most of the distortion caused by contact with the base material. Furthermore, as the material for the unit buff body, long fibers such as synthetic fibers such as polyester and nylon are more preferable than cotton cloth because they do not generate thread waste.

[0037] Two or more types of shearing force applying means may be appropriately combined. Examples of the present invention will be specifically described below, but the present invention is not limited only to these Examples.

Example 1 Polyethylene (
"Mirason 16" manufactured by Mitsui Petrochemical Industries, Ltd.) with a thickness of 15
100 parts by weight of a hydrogenated styrene-butadiene-styrene block copolymer ("Califlex TR1102" manufactured by Shell Chemical Co., Ltd.) was applied to the surface opposite to the polyethylene surface of the extrusion-laminated base material so that Sex-imparting resin (“Clearon P100” manufactured by Yasushi Oil Industries Co., Ltd.)
A mixture of 100 parts by weight was coated and dried to have a solid content thickness of 40 μm without being dissolved in toluene. Place the obtained adhesive sheet 1 on the surface opposite to the adhesive layer (back side).
The surface of the paper is processed to apply a shearing force using a metal roll 5 that rotates in the direction opposite to the direction shown by the arrow in FIG. Obtained.

The conditions for applying the shearing force are: line speed 10 m/min, roll speed 110 m/min, tension applied to the sheet 20 kg/m, and the coefficient of sliding friction between the metal roll and the polyethylene surface of the adhesive sheet is 0.7. Met.

Example 2 Styrene-butadiene-
100 parts by weight of a hydrogenated styrene block copolymer (“Krayton G1652” manufactured by Shell Chemical Co., Ltd.) and a tackifying resin (“Clearon P100” manufactured by Yasushi Kogyo Co., Ltd.)
Rolling was carried out in the same manner as in Example 1, except that a mixture of 20 parts by weight and 20 parts by weight was made into a homogeneous solution (solid content concentration 20 wt%) in toluene, and the adhesive solution was coated and dried so that the solid content thickness was 10 μm. The patient was in critical condition.

Example 3 The same polyethylene as in Example 2, a mixture of a hydrogenated styrene-butadiene-styrene block copolymer and a tackifying resin (toluene was not used) were co-produced by a T-die method. A rolled body was obtained in the same manner as in Example 2 except that it was extruded into a pressure-sensitive adhesive sheet.

Example 4 A rolled body was obtained in the same manner as in Example 2 except that the conditions for applying shearing force were changed. The conditions for applying shearing force are: line speed 10 m/min, roll speed 40 m/min,
Tension applied to the sheet: 4 kg/m, gas outlet 28 in Figure 2
10 kg perpendicularly to the contact area between the back of the base material and the roll.
An air flow of /cm2 was applied.

Example 5 Polyethylene with a thickness of 100 μm (Hizex 33 manufactured by Mitsui Petrochemical Industries, Ltd.) was molded by the inflation method.
00F") Example 1 was applied on one side of the base material made of film.
A homogeneous solution of the same mixture in toluene (solid content concentration 4)
0% by weight) with a solid content of 40μ
It was coated and dried so that it became m. As shown in FIG. 3, the obtained adhesive sheet 1 is surface-treated to apply shearing force to the surface (back surface) opposite to the adhesive layer using a counter-rotating roll 15 to which a nylon cloth 6 is attached. The material was passed through pinch rolls 8 and 9 and wound around a paper core having an inner diameter of 3 inches to obtain a rolled body.

The conditions for applying shearing force were a line speed of 10 m/min, a roll speed of 90 m/min, and a tension applied to the sheet of 8 kg/m. Example 6 The same polyethylene as in Example 5 and a mixture of a hydrogenated styrene-butadiene-styrene block copolymer and a tackifier resin (toluene was not used) were coextruded using a T-die method to create an adhesive. A rolled body was obtained in the same manner as in Example 5 except that it was made into a sheet.

Example 7 A styrene-butadiene-styrene block copolymer was hydrogenated on one side of a base material made of a polyethylene film (Mirason 12, manufactured by Mitsui Petrochemical Industries, Ltd.) with a thickness of 60 μm molded by the T-die method. A homogeneous solution of a mixture of 100 parts by weight of a substance ("Tuftec H1052" manufactured by Asahi Kasei Industries, Ltd.) and 40 parts by weight of a tackifier resin ("Alcon P125" manufactured by Arakawa Chemical Industries, Ltd.) was made into a homogeneous solution in toluene (solid content concentration 30% by weight). The adhesive solution prepared above was applied and dried to a solid content thickness of 10 μm. The obtained adhesive sheet 1 was attached to a unit buff body (bias cotton buff M-0 with center fitting made by Koyosha Co., Ltd. with a center fitting) made of cotton cloth and having an outer diameter of 300 mm and rotating in the opposite direction (back side). ), as shown in Figure 3, the surface is processed to apply shearing force, the static electricity is removed, and the cotton dust adhering to the surface is suctioned off. The material was wound around a paper core to obtain a rolled body.

The conditions for applying shearing force were a line speed of 20 m/min and a roll speed of 90 m/min. Example 8 A rolled body was obtained in the same manner as in Example 7 except that a unit buff body made of nylon long fibers was used for the buff roll.

No lint was generated from the unit baffle roll, and no deformation, wrinkles, scratches, etc. of the sheet were observed. Comparative Example 1 A rolled body was obtained in the same manner as in Example 3 except that no shearing force was applied.

Comparative Example 2 A rolled body was obtained in the same manner as in Example 6 except that no shearing force was applied. Comparative Example 3 A rolled body was obtained in the same manner as in Example 7 except that no shearing force was applied.

The adhesive sheet rolls obtained in the above Examples and Comparative Examples were left under three combinations of conditions, and the unrolling force and initial adhesive force were measured in the following manner. The measurement results are summarized in Table 1. Unrolling force: The force required when unwinding the adhesive sheet from the roll at a speed of 30 m/min is expressed as a value converted to g/50 mm width. Initial adhesive strength: The adhesive sheet unwound from the roll was pasted on a stainless steel plate specified in JIS Z0237 using a laminator, left at 23°C for 30 minutes, and then 300mm thick at 23°C.
The force required to peel off at an angle of 180° at a speed of /min is expressed as g/50 mm width conversion value.

[0050]

[Table 1]

As mentioned above, in the adhesive sheet rolls obtained in Examples 1 to 8, the sheets did not undergo elongation deformation when being peeled off from the roll, and the initial adhesive strength did not change after peeling. I understand. On the other hand, in the adhesive sheet rolls obtained in Comparative Examples 1 to 3, the unfolding force increased over time,
It can be seen that the sheet is elongated and deformed, making it virtually unusable.

[0052]

[Effect of the invention] The adhesive tape or sheet of the present invention has
Since no mold release agent is used, the manufacturing process is simplified, and the process required for mold release treatment is simple and can be done in-line.
In addition, it has good unwinding properties even after aging and can maintain its releasability over a long period of time, and there is no adverse effect on quality such as contamination of the surface of the adherend.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment in which shearing force is applied to the back surface of the base material of the adhesive tape or sheet of the present invention.

FIG. 2 is an explanatory view showing another embodiment in which shearing force is applied to the back surface of the base material of the adhesive tape or sheet of the present invention.

FIG. 3 is an explanatory view showing an embodiment in which shearing force is applied to the back surface of the base material of the adhesive tape or sheet of the present invention using a buff roll.

FIG. 4 is a side view showing an example of a unit buff body that applies shearing force to the back surface of the base material of the adhesive tape or sheet of the present invention.

FIG. 5 is an explanatory view showing an embodiment in which shearing force is applied to the back surface of the base material of the adhesive tape or sheet of the present invention without using rolls.

[Explanation of symbols]

1 Adhesive sheet 2 Guide roll 5 roll 6 Fiber or fiber molded body 8 Pinch roll 9 Pinch roll 15 Buff roll 21 Pinch roll 22 Pinch roll 23 Turn roll 24 Reverse (or forward) rotating roll 25 Turn roll 26 Pinch roll 27 Pinch roll 28 Gas outlet

Claims (7)

[Claims] Claim 1: An adhesive tape or sheet in which an adhesive layer is laminated on one side of a base layer made of a polyolefin resin, optionally with an intermediate layer interposed therebetween, in which a shearing force is applied to the back side of the base layer. An adhesive tape or sheet characterized by having a surface-treated surface. 2. The adhesive tape or sheet according to claim 1, wherein the back surface of the base material layer is surface-treated by applying a shearing force by generating sliding friction between the base material and a solid substance. . 3. The pressure-sensitive adhesive tape or sheet according to claim 2, wherein the solid material is in the form of a roll, and the surface layer thereof is fibers, fiber molded bodies, or metal. [Claim 4] Claim 2 wherein the solid substance is bufflor.
Adhesive tape or sheet as described. 5. Claim 1, wherein a large number of parallel lines are formed along the longitudinal direction on the back surface of the surface-treated base layer.
, the adhesive tape or sheet according to 2, 3 or 4. 6. Generating sliding friction between the base material and the solid substance while applying a gas flow of 1 to 50 kg/cm2 to the part of the back surface of the base material layer that is in contact with the solid substance of the base material. The pressure-sensitive adhesive tape or sheet according to claim 2, 3, 4 or 5, which has been surface-treated by being subjected to shearing force. 7. A solid substance is brought into contact with the back surface of the base material layer of an adhesive tape or sheet in which an adhesive layer is laminated on one side of the base material layer made of polyolefin resin, optionally with an intermediate layer interposed therebetween. A method for surface treatment of adhesive tapes or sheets, characterized by creating sliding friction between the material and a solid substance to apply shearing force.