JP2003342544A - Double-sided adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a double-sided adhesive tape smoothly peeled without accompanying interlaminar fracture when peeling the tape again from an adherent. <P>SOLUTION: The double-sided adhesive tape is obtained by forming adhesive layers on both sides of a nonwoven fabric base material. The adhesive tape has ≤10% rate of interlaminar fracture area in the double-sided adhesive tape, and ≥20 N/10 mm tensile strength in both of the MD direction (machine direction) and TD direction (transverse direction). The double-sided adhesive tape is suitably used for a repeeling application. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a double-sided adhesive tape. More specifically, the present invention relates to a double-sided adhesive tape having excellent releasability, which does not break inside a nonwoven fabric as a supporting substrate when it is peeled off after being adhered to an adherend such as plastic or metal.

[0002]

2. Description of the Related Art Double-sided adhesive tapes (or sheets) are used in various industrial fields such as home electric appliances, automobiles, and office automation equipment as a joining means having good workability and high reliability of adhesion. Further, in recent years, from the viewpoint of resource saving, in many cases, recyclable parts used in products are often disassembled and reused after use. At this time, when the parts are joined together using the double-sided adhesive tape, it may be necessary to remove the double-sided adhesive tape attached to the parts.

As a double-sided adhesive tape which requires such removability, various proposals have been made so far. For example, in Japanese Unexamined Patent Publication No. 7-70527, an adhesive layer is provided on both sides of a non-woven fabric substrate containing Manila hemp as a main component and having tensile strengths of 1 kg / 15 mm or more in the longitudinal direction and the transverse direction, and at least one of them is provided. A double-sided pressure-sensitive adhesive tape has been proposed in which the pressure-sensitive adhesive layer on the surface is a water-soluble pressure-sensitive adhesive layer. Further, Japanese Unexamined Patent Publication No. 9-272850 discloses a double-sided adhesive tape in which an acrylic adhesive is provided on both sides of a base material, in which the base material and the acrylic adhesive have specific physical properties.

Most of the double-sided adhesive tapes in these conventional proposals are based on a non-woven fabric, and as a point of improving the removability, an adhesive should not remain on the surface of the adherend when the double-sided adhesive tape is peeled off. To prevent (adhesive residue prevention)
In many cases, the main focus is to prevent the double-sided adhesive tape from being cut during peeling.

[0005]

However, in the recycling process of the assembled parts in which the parts are joined by using the double-sided adhesive tape, first, the parts joined by the double-sided adhesive tape are peeled off and disassembled. After that, the double-sided adhesive tape simple substance attached to the component is peeled off from the component (adherend). At this time, many of the conventional double-sided adhesive tapes with high tensile strength are destroyed (interlayer destruction) in the part of the non-woven fabric which is the base material in the initial part peeling (disassembly) process between parts, The non-woven fabric is split into two parts on both surfaces of the disassembled parts, and the residue of the double-sided adhesive tape, which is the exposed part of the split non-woven fabric, is attached, and the work to remove this residue from the part surface is recycled. It was the most inefficient work in the process.

In view of the above-mentioned conventional circumstances, the present invention, when disassembling an assembled part joined by using a double-sided adhesive tape, when the parts are peeled off, the double-sided adhesive tape breaks between the layers of the nonwoven fabric ( If the double-sided adhesive tape that is not separated) is peeled off at the interface between one of the adherend parts and the adhesive layer of the double-sided adhesive tape, and the other part is peeled off, double-sided adhesive The tape is cut,
It is an object of the present invention to obtain a double-sided adhesive tape having excellent releasability that can be smoothly peeled off without causing adhesive residue.

[0007]

As a result of intensive studies to solve the above problems, the present inventors have found that in a double-sided adhesive tape using a non-woven fabric as a base material, adhesion to a specific adherend
The present inventors have found that the above problems can be solved by specifying the interlaminar fracture area ratio of the double-sided adhesive tape after peeling and by specifying the tensile strength of the double-sided adhesive tape, and have achieved the present invention.

That is, the present invention is a double-sided adhesive tape having a pressure-sensitive adhesive layer formed on both sides of a non-woven fabric substrate, wherein the double-sided adhesive tape has an interlaminar fracture area ratio of 10% or less and a double-sided adhesive tape. A double-sided adhesive tape having a tensile strength of 20 N / 10 mm or more in both the MD direction (longitudinal direction) and the TD direction (lateral direction). This double-sided adhesive tape is used, for example, for re-peeling applications.

In the present invention, the interlaminar fracture area ratio is t (thickness) = 0.1 m when both sides of a double-sided tape cut into 15 mm × 15 mm are cut into 20 mm × 100 mm.
m aluminum foil is attached, and after sufficient adhesiveness is secured by storing at 60 ° C for 24 hours, it is gradually cooled to room temperature, and both ends of the aluminum foil are held by hand, and T peeling is performed by hand at a speed of about 10 m / min. It means a value obtained as a ratio (%) of the area of the non-woven fabric remaining on the aluminum foil, which is broken between the layers (interlayer breakage area), to the total bonding area.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the double-sided adhesive tape of the present invention, a pressure-sensitive adhesive layer is formed on both surfaces of a non-woven fabric substrate. As the non-woven fabric constituting the base material, if the interlaminar fracture area ratio and the tensile strength of the double-sided adhesive tape finally satisfy the ranges specified in the present invention, it is commonly used as the base material of the double-sided adhesive tape. Any known non-woven fabric can be used. Typical examples thereof include manila hemp; pulp; chemical fibers such as rayon, acetate fibers, polyester fibers, polyvinyl alcohol fibers, polyamide fibers, and polyolefin fibers; and mixtures thereof. Among these, a nonwoven fabric obtained by mixing manila hemp with chemical fibers (for example, polyvinyl alcohol fibers) is particularly preferable. The base material may be impregnated with a resin (binder) such as viscose in order to bond the non-woven fabric fibers to each other.

The thickness of the non-woven fabric substrate can be appropriately selected within a range that does not impair handleability, etc., but is generally 20 to 120 μm.
The degree is preferably about 30 to 90 μm. Further, the density of the non-woven fabric substrate varies depending on the constituent material of the non-woven fabric, and can be selected within a wide range of, for example, about 0.1 to 0.8 g / cm ^3, but the pressure-sensitive adhesive can be easily impregnated and the interlayer strength of the non-woven fabric can be improved. From the point, especially 0.25 to 0.45 g / cm
^{About 3} is preferable.

As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer,
A conventional or known adhesive can be used in the adhesive tape,
For example, a rubber-based pressure-sensitive adhesive in which an additive such as a tackifying resin is mixed with an elastomer; a copolymer of (meth) acrylic acid alkyl ester or the (meth) acrylic acid alkyl ester and another unsaturated monomer Examples thereof include an acrylic pressure-sensitive adhesive containing a copolymer-based acrylic polymer as a base polymer, and if necessary, additives such as a crosslinking agent and a tackifying resin, and a silicone-based pressure-sensitive adhesive.

Among these, the pressure-sensitive adhesive that is preferably used is, for example, an acrylic pressure-sensitive adhesive whose main component is an acrylic polymer dissolved in a hydrocarbon solvent and applied.
In particular, the storage elastic modulus (G ') is 4.5 × 10 ⁴ Pa to 6.0.
Good peelability is obtained by using an acrylic pressure-sensitive adhesive of about × 10 ⁴ Pa. The storage modulus (G ') of the acrylic pressure-sensitive adhesive is the kind and ratio of the monomers of the acrylic polymer constituting the acrylic pressure-sensitive adhesive, the kind and amount of the polymerization initiator used, and the kind and amount of the cross-linking agent. It can be adjusted by appropriately selecting the polymerization method and the like. Storage modulus (G ')
Is, for example, using a dynamic viscoelasticity measuring device RDS-11 manufactured by Rheometric Co., using a solid content of an acrylic adhesive having a thickness of about 1.5 mm as a sample, and using a jig of a parallel plate having a diameter of 7.9 mm. , Can be measured under the condition of frequency 1 Hz. The thickness of the adhesive layer is not particularly limited, but is usually 30.
-100 μm, preferably 50-80 μm.

In the double-sided adhesive tape of the present invention, the interlaminar fracture area ratio is 10% or less, preferably 5% or less,
Most preferably, it is 0%. If the interlaminar fracture area ratio is 10% or less, it is possible to prevent non-woven fabric interlaminar fracture when the assembled parts joined by using the double-sided adhesive tape are disassembled by peeling. That is, when the double-sided adhesive tape is peeled off from the assembly part as the adherend, first, the double-sided adhesive tape is separated at the interface between one of the assembly parts and the pressure-sensitive adhesive layer of the double-sided adhesive tape, and the double-sided adhesive tape is adhered to the other part. The adhesive tape can be easily peeled off from the surface of the component with almost no interlayer destruction, and the disassembly property of the component is significantly improved.

On the other hand, when the interlaminar fracture area ratio exceeds 10%, when the parts are disassembled for the purpose of recycling, the double-sided adhesive tape has a considerably large portion left in a split state on the disassembled two parts surfaces. Become. Not only is the splitting portion difficult to peel off because the strength of the nonwoven fabric is significantly reduced, but the splitting area is doubled as a result. Therefore, the dismantability of the parts is significantly impaired.

In the double-sided adhesive tape of the present invention, in order to reduce the interlaminar fracture area ratio to 10% or less, for example, as a non-woven fabric, a small amount of chemical fiber such as polyvinyl alcohol fiber such as vinylon fiber is mixed with Manila hemp. It is conceivable to use a non-woven fabric or to sufficiently impregnate the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer over the whole non-woven fabric layer, or to remarkably improve the interlaminar strength of the non-woven fabric, to apply an appropriate binder to the non-woven fabric, The method is not particularly limited. However, as a suitable means, for example, using a non-woven fabric substrate having a relatively low density, or by increasing the application amount or the number of times of application of the adhesive to the non-woven fabric substrate,
A method of impregnating the entire non-woven fabric layer with an adhesive is adopted.

In the double-sided adhesive tape of the present invention, the tensile strength of the double-sided adhesive tape is further in the MD direction (longitudinal direction;
20 N / both in flow direction) and TD direction (transverse direction; width direction)
It should be 10 mm or more. The tensile strength is preferably 20 to 30 N / 10 m in both directions.
It is about m. Tensile strength of double-sided adhesive tape is MD, T
If the adhesive force is 20 N / 10 mm or more in both directions D, even if the adhesive strength is increased by fixing for a long period of time, there will be almost no tearing, and the disassembling property of the component will be further improved.

The tensile strength of the double-sided adhesive tape is in the MD direction,
When it is less than 20 N / 10 mm in any of the TD directions, when the adhesive force is increased by fixing for a long period of time, it easily breaks under the high-speed peeling work condition by the hand of the person mainly in the dismantling work, The dismantability of components is likely to deteriorate.

The tensile strength of the double-sided adhesive tape is, for example,
It can be adjusted by appropriately selecting the type of fibers constituting the nonwoven fabric (material, length, thickness, etc.), the manufacturing conditions of the nonwoven fabric (for example, the type and amount of the binder to be impregnated, the drying temperature, the heat treatment temperature, etc.).

Tensile strength of the double-sided adhesive tape was measured by using a tensile tester for a double-sided adhesive tape having a width of 10 mm, which was cut in the TD direction and the MD direction.
m, and the pulling speed is 300 mm / min.

The double-sided adhesive tape of the present invention can be produced by forming a pressure-sensitive adhesive layer on both sides of a non-woven fabric substrate. For forming the pressure-sensitive adhesive layer, a conventional or known method in the field of pressure-sensitive adhesive tape can be adopted. For example, as a method for forming the pressure-sensitive adhesive layer, a direct copying method in which the non-woven fabric substrate is directly coated with the pressure-sensitive adhesive composition and dried, or a release liner is coated with the pressure-sensitive adhesive composition and dried, and then transferred to a non-woven fabric substrate. Law, etc. Of these, the direct copying method is particularly preferable.

The double-sided adhesive tape of the present invention can be used for semi-permanently fixing an adherend. However, when the double-sided adhesive tape is once adhered to an adherend and then repeeled after a predetermined period of time, the adherend is adhered. Since it can be easily and cleanly peeled from the body, it is particularly suitable for re-peeling applications.

[0023]

EXAMPLES The present invention will now be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 5 parts by weight of acrylic acid, 95 parts by weight of butyl acrylate, and 200 parts by weight of toluene as a polymerization solvent were placed in a three-necked flask and stirred for 2 hours while introducing nitrogen gas.
After removing oxygen in the polymerization system in this manner, 0.1 part by weight of benzoyl peroxide was added, and the temperature was raised to 80 ° C. to carry out a polymerization reaction for 6 hours. The weight average molecular weight of the obtained polymer was 400,000. 2 parts by weight of an isocyanate cross-linking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) as a cross-linking agent was added to 100 parts by weight of the solid content of this polymer, and the mixture was sufficiently stirred to give an acrylic pressure-sensitive adhesive. Prepared. As a non-woven fabric base material, a mixture of 99% by weight of Manila hemp and 1% by weight of vinylon has a thickness of 75 μm and a density of 0.31.
The above acrylic pressure-sensitive adhesive was applied to both sides of a non-woven fabric of g / cm ³ by the direct copying method so as to have the same weight, and dried to form a pressure-sensitive adhesive layer, thereby producing a double-sided tape having a total thickness of 160 μm. The storage elastic modulus at 50 ° C. of the adhesive layer after coating and drying was 5.0 × 10 ⁴ Pa.

Comparative Example 1 As a non-woven fabric substrate, the same acrylic pressure-sensitive adhesive as in Example 1 was applied directly to both sides of a non-woven fabric of 100% Manila hemp (thickness 46 μm, density 0.37 g / cm ³ ). Apply to a thickness and dry to form an adhesive layer, total thickness 1
A 60 μm double-sided adhesive tape was prepared.

Comparative Example 2 As a non-woven fabric base material, pulp and rayon fibers were used in a weight ratio of 5
The same acrylic adhesive as in Example 1 was applied to both sides of a non-woven fabric (thickness 39 μm, density 0.39 g / cm ³ ) blended at 0:50 by the direct copying method so as to have the same thickness, and dried. Then, a pressure-sensitive adhesive layer was formed to prepare a double-sided adhesive tape having a total thickness of 160 μm.

Evaluation Test (Tape Tensile Strength) A double-sided adhesive tape having a width of 10 mm cut in the TD direction and the MD direction was subjected to a tensile tester with a chuck distance of 50 mm and a pulling speed of 300 mm.
Measure the maximum stress that occurs when pulled under the condition of / min,
The tensile strength in the TD and MD directions was used.

(Interlayer destructive test) Aluminum foil of t (thickness) = 0.1 mm cut to 20 mm × 100 mm was attached to both sides of a double-sided adhesive tape cut to 15 mm × 15 mm, stored at 60 ° C. for 24 hours, and then at room temperature. Slowly cool down to the end, hold both ends of the aluminum foil by hand, and perform T by hand at a speed of about 10 m / min.
Peeling was performed, and the area ratio (interlayer fracture area ratio) in which the inside of the nonwoven fabric was broken from the adhesive surface after peeling was calculated as follows. That is, the peeled surface is captured as an image with a photographic machine, printed on photographic paper, the double-sided tape printing part is cut out and its weight (A) is measured, and also the interlayer breakdown part is cut out and its weight (B) is measured. Then
The value of (B / A) × 100 was defined as the interlayer fracture area ratio (%).

(Removability test) A sample in which the adhesiveness was lost by shaking dusting powder on one surface of a double-sided adhesive tape having a width of 5 mm, which was cut in the TD direction and the MD direction, respectively, had a thickness of 2 m.
30 m under the condition of 60 ° C and 95% RH by affixing it to the PC ABS (blend of polycarbonate and ABS) plate of m.
Left for days. After slowly cooling to room temperature, using a tensile tester,
Peeling speed of each double-sided adhesive tape 300 mm / min, 180 °
The tape was peeled off, and the tearing property and the breakage form of the tape in the TD direction and the MD direction were confirmed. Regarding the shredding property, the same test was carried out with N = 5, and the case where it was not torn in all the tests was evaluated as ◯, and the case where it was torn twice in 5 tests was evaluated as Δ.

Table 1 shows the above test results.

[Table 1]

As is clear from Table 1, the double-sided adhesive tapes of the examples are peeled off without breaking at the interface between the adhesive layer of the tape and the adherend when re-peeling. On the other hand, in the double-sided tape of Comparative Example 1 having a large interlaminar fracture area ratio, upon re-peeling, it breaks between the layers of the non-woven fabric substrate, and fragments of the non-woven fabric substrate remain on the adherend. In addition, the double-sided tape of Comparative Example 2 having a small tape tensile strength has a drawback that it is easily broken.

[0032]

EFFECTS OF THE INVENTION According to the double-sided adhesive tape of the present invention, when peeling off parts joined by using the double-sided adhesive tape,
It does not break (separate) between the layers of the non-woven fabric base material, and is easily peeled off without leaving any adhesive residue at the interface between the joined parts and the adhesive layer of the double-sided adhesive tape. Therefore, the peeling work of the double-sided adhesive tape can be performed extremely efficiently, and the disassembly and recycling of the assembled parts are facilitated. Further, even if it is fixed for a long period of time, it can be peeled off without tearing, so that disassembly of the assembled parts can be greatly improved.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoichiro Goto             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Masashi Hamada             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 4J004 AA10 AA11 AB01 CA02 CA03                       CA06 CB01 CC02 EA05 FA05                       FA10                 4J040 DF041 DF051 EK001 JA09                       JB09 MA10 MA11 MB02 PA23                       PA42

Claims (2)

[Claims] 1. A double-sided adhesive tape in which a pressure-sensitive adhesive layer is formed on both surfaces of a non-woven fabric substrate, wherein the double-sided adhesive tape has an interlaminar fracture area ratio of 10% or less, and the double-sided adhesive tape has a tensile strength of MD. Direction (vertical direction) and TD direction (horizontal direction)
Both sides are 20 N / 10 mm or more, The double-sided adhesive tape characterized by the above-mentioned. 2. The double-sided adhesive tape according to claim 1, which is used for repeeling.