JPH05222346A - Conductive pressure-sensitive adhesive tape - Google Patents

Abstract

PURPOSE:To provide the title tape excellent in conductivity, pressure-sensitive adhesiveness, etc., and usable as a conductive member of, e.g. electronic equipment. CONSTITUTION:The title tape is prepared by applying a conductive pressure- sensitive adhesive prepared by dispersing a conductive substance such as a metallic powder in a pressure-sensitive substance. The above conductive substance comprises agglomerated conductive particles having a dimension in the lengthwise direction at most twice as large as the thickness of the pressure- sensitive layer, desirably has a dimension in the lengthwise direction at most twice as large as the thickness of the adhesive layer, and is contained in an amount of 2.5-50 pts.wt. per 100 pts.wt. solid matter of the adhesive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive pressure-sensitive adhesive tape used as a conductive member for electronic equipment and the like, and more particularly to a conductive pressure-sensitive adhesive tape having excellent conductivity and pressure-sensitive adhesive properties.

[0002]

2. Description of the Related Art An electromagnetic shielding material for a plastic container containing a computer, a communication device, an electronic device such as an amplifier, a ground wire for electric parts, a leakage current removing material for fixing and preventing vibration, and a triboelectric material. BACKGROUND ART A conductive adhesive tape having conductivity and easy adhesion such as an adhesive tape is used as a material for preventing ignition due to sparks due to static electricity, a weak heating element for preventing condensation and freezing.

As the conductive adhesive tape for the above-mentioned applications, a conductive adhesive having conductive particles such as metal powder dispersed in an adhesive substance has heretofore been applied to one side of a conductive base material such as a metal foil. Worked materials have been used, and copper foil, aluminum foil, stainless steel foil, nickel foil, etc. are used as the support, and copper powder, silver powder, nickel powder, aluminum powder, etc. are used as the conductive particles, and as a binder. Acrylic resin type, latex type, silicone resin type and the like have been used.

[0004]

As described above, the conductive adhesive tape is a composite of a support and an adhesive, and is made to have conductivity, and the constitution thereof is as follows: Japanese Patent Publication No. 46-15240.
As described in JP-B No. 2-117980, the absolute condition is that the diameter of the conductive particles is substantially equal to or smaller than the thickness of the adhesive layer. However, apart from the case where the size of the conductive particles is equal to the thickness of the adhesive layer, when the size of the conductive particles is smaller than the thickness of the adhesive layer, the adhesive property is good, but the conductivity It tends to be insufficient, and there was a problem in practical use.

An object of the present invention is to solve the problems of the prior art described above and to provide a conductive adhesive tape exhibiting excellent conductivity and adhesive properties.

[0006]

Means for Solving the Problems The above-mentioned object is to provide a conductive adhesive obtained by coating a conductive flexible support with a conductive adhesive in which a conductive substance such as metal powder is dispersed in an adhesive substance. In the pressure-sensitive adhesive tape, the conductive substance is a conductive pressure-sensitive adhesive tape which is a conductive particle aggregate having a dimension in the longitudinal direction of at least equal to or less than twice the thickness of the pressure-sensitive adhesive layer, and preferably the above-mentioned conductive The length of the elastic substance is at least equal to the thickness of the adhesive layer 2
Less than double the amount, and the blending amount is the solid content of the adhesive.
This can be achieved by using a conductive adhesive tape which is 2.5 to 50 parts by weight with respect to 100 parts by weight.

In addition to the conductive particle agglomerates whose longitudinal dimension is at least equal to or less than twice the thickness of the pressure-sensitive adhesive layer, the conductive particles whose longitudinal dimension is less than the pressure-sensitive adhesive layer thickness or the same. It is also possible to prepare a composition containing an aggregate.

[0008]

[Function] In order for the conductive adhesive tape to exhibit sufficient conductivity with respect to the conductive object (adherent) to which it is attached, the conductive particles in the adhesive layer form agglomerates to form particles. They may be in contact with each other and may be vertically connected at any place in the pressure-sensitive adhesive layer, and the conductive flexible support and the adherend may be almost connected by the conductive particle aggregate. desirable.

In order to electrically connect the conductive flexible support and the adherend, one end of the conductive particle agglomerate used is almost in contact with the conductive flexible support, and the other end. Should be almost in contact with the adherend. for that purpose,
It is desirable that the dimension of the conductive particle aggregate in the longitudinal direction is at least equal to or larger than the thickness of the pressure-sensitive adhesive layer. However, when the size is too large compared to the thickness of the pressure-sensitive adhesive layer and protrudes largely on the surface of the pressure-sensitive adhesive layer, there is no negative effect on the conductivity, but the adhesive property is adversely affected. .. For this reason, it is desirable that the size of the conductive particle aggregate is such that the dimension in the longitudinal direction is 1 time or more and less than 2 times the thickness of the adhesive layer. Further, as the amount of the conductive particle aggregate to be blended, the adhesive solid content
2.5 to 50 parts by weight, more preferably 5 to 100 parts by weight
It is preferably 25 parts by weight. It is also possible to mix together the conductive particle agglomerates of the above dimensions with conductive particles having a dimension in the longitudinal direction less than the thickness of the pressure-sensitive adhesive layer or an aggregate thereof.

The conductive flexible support used in the conductive pressure-sensitive adhesive tape of the present invention includes metal foil such as rolled copper foil, electrolytic copper foil, aluminum foil, nickel foil, and stainless steel foil, and plated polyester. An example of such a material is a mesh made. The conductive particles usable in the tape of the present invention include nickel powder, copper powder, silver powder, aluminum powder and carbon powder. Further, the pressure-sensitive adhesive has a function of adhering the tape to an object, and examples of the binder resin include acrylic resin-based, latex-based, and silicone resin-based resins.

[0011]

EXAMPLES The conductive adhesive tape of the present invention will be described in detail below with reference to examples.

[0012]

Example 1 First, nickel powder was classified using a vibrating screener, and powder that passed through 200 mesh and remained on 330 mesh was collected. Next, 25 parts by weight of the above nickel powder was added to a solution prepared by dissolving 7.5 parts by weight of an amide-based dispersant in 30 parts by weight of toluene, and dispersed using a stirrer. After the dispersion, 250 parts by weight of an acrylic resin-based adhesive (however, solid content 40%) and 0.25 part by weight of a crosslinking agent were added and mixed to prepare a conductive adhesive. The conductive adhesive obtained was coated on a release paper to a thickness of 40 μm (the thickness after drying) and then transferred to a copper foil to give a conductive adhesive tape.

After aging the obtained pressure-sensitive adhesive tape for 7 days, various characteristics (resistance value, adhesive strength, tack) as a conductive pressure-sensitive adhesive tape were measured and the results shown in Table 1 were obtained. From this result, the resistance value, adhesive strength,
It can be seen that it has a tack value. In addition, when the size of the nickel powder aggregate in the pressure-sensitive adhesive layer was examined for this sample, most of its longitudinal dimension was equal to or greater than the pressure-sensitive adhesive layer thickness, but twice the pressure-sensitive adhesive layer thickness. Nothing above was recognized.

[0014]

Comparative Example 1 Nickel powder was classified using a vibrating screener,
A powder which passed through 100 mesh and stopped on 200 mesh was collected, and a conductive adhesive tape was prepared in the same manner as in Example 1 except that 25 parts by weight of this powder was used.

The same measurement as above was performed on the obtained tape, and the results shown in Table 1 were obtained. From this result, a satisfactory value can be obtained for the resistance value, but the adhesive strength,
It can be seen that the tack is extremely low. When the size of the nickel powder agglomerates in the pressure-sensitive adhesive layer was examined for this sample, most of the dimension in the longitudinal direction exceeded twice the thickness of the pressure-sensitive adhesive layer. The dimension in the widthwise direction was also equal to or larger than the thickness of the adhesive layer.

[0016]

[Comparative Example 2] Nickel powder was classified using a vibration sifter 33
A powder that passed through 0 mesh was collected, and a conductive adhesive tape was prepared in the same manner as in Example 1 except that 25 parts by weight of this powder was used.

The same measurement as above was performed on the obtained tape, and the results shown in Table 1 were obtained. From this result, it can be seen that although the adhesive property shows a satisfactory value, the resistance value is extremely large. Further, when the size of the nickel powder aggregate in the pressure-sensitive adhesive layer was examined for this sample, the dimension in the longitudinal direction was almost equal to or less than the thickness of the pressure-sensitive adhesive layer.

[0018]

[Table 1]

[0019]

[Examples 2, 3, 4] Nickel powder was classified using a vibrating screener, and powder that passed through 200 mesh and remained on 330 mesh was collected. Then, the above nickel powder was added to each of the liquids prepared by dissolving 7.5 parts by weight of the amide-based dispersant in 30 parts by weight of toluene, and the dispersion was performed using a stirrer. After the dispersion, 250 parts by weight of the acrylic resin adhesive (however, solid content 40%) and 0.25 parts by weight of the crosslinking agent were added and mixed to prepare a conductive adhesive. The conductive adhesive obtained was coated on a release paper to a thickness of 40 μm (the thickness after drying) and then transferred onto a copper foil to obtain a conductive adhesive tape.

After aging the above tape for 7 days, various characteristics as a conductive adhesive tape were measured and the results shown in Table 2 were obtained. From these results, it can be seen that all the samples show sufficiently satisfactory characteristics.

[0021]

[Comparative Examples 3 and 4] Conductive pressure-sensitive adhesive tapes were prepared in exactly the same manner as in Example 1 except that the amount of nickel powder added was changed to the parts by weight shown in Table 2.

The results of measuring the characteristics of the conductive adhesive tape are shown in Table 2. From these results, when the amount of nickel powder added is as small as 1 part by weight, the adhesive strength and tack show satisfactory values. It is known that the resistance value becomes close to an order of magnitude, and that when the nickel powder addition amount is too large at 75 parts by weight, the resistance value shows a satisfactory value, but both the adhesive strength and the tack become significantly small values. ..

[0023]

[Table 2]

[0024]

[Examples 5 and 6] Nickel powder was classified using a vibrating screener to obtain nickel powder (A) that passed through 200 mesh and stopped on 330 mesh and nickel powder (B) that passed through 330 mesh. It was A conductive pressure-sensitive adhesive tape was prepared in the same manner as in Example 1 except that the obtained nickel powder was added in the proportions by weight shown in Table 3, respectively.

The results of measuring the respective properties of the obtained conductive pressure-sensitive adhesive tape are shown in Table 3. From these results, it can be understood that all the samples have sufficiently satisfactory properties.

[0026]

Comparative Example 5 Nickel powder (A) used in Examples 5 and 6 and
Conductive pressure-sensitive adhesive tapes were prepared in the same manner as in Examples 5 and 6 except that 50 parts by weight of nickel powder (B) alone was added instead of (B).

The results of measuring the respective properties of the obtained conductive pressure-sensitive adhesive tape are shown in Table 3. From these results, in the case of the sample using nickel powder consisting of only fine powder as in this example, It can be seen that although the adhesive strength and the tack are satisfactory, the resistance value is remarkably high.

[0028]

[Table 3]

[0029]

As described above, the use of the conductive adhesive tape as the adhesive tape having the constitution of the present invention solves the problems of the prior art and provides excellent conductivity and adhesive properties. It was possible to provide a conductive adhesive tape having

Claims (3)

[Claims] 1. A conductive pressure-sensitive adhesive tape obtained by applying a conductive pressure-sensitive adhesive having a conductive substance such as metal powder dispersed in a pressure-sensitive adhesive substance on a conductive flexible support, wherein the conductive substance is Is a conductive particle agglomerate whose longitudinal dimension is at least equal to or less than twice the thickness of the pressure-sensitive adhesive layer, and is a conductive pressure-sensitive adhesive tape. 2. A conductive pressure-sensitive adhesive tape obtained by applying a conductive pressure-sensitive adhesive comprising a conductive substance such as metal powder dispersed in a pressure-sensitive adhesive substance on a conductive flexible support, wherein the conductive substance is Is a conductive particle agglomerate whose longitudinal dimension is at least equal to or less than twice the thickness of the pressure-sensitive adhesive layer, and the compounding amount is 2.5 to 50 parts by weight with respect to 100 parts by weight of the solid content of the adhesive. Conductive adhesive tape characterized by being a part. 3. A conductive particle aggregate whose longitudinal dimension is at least equal to or less than twice the thickness of the pressure-sensitive adhesive layer, and together with conductive particles whose longitudinal dimension is less than the thickness of the pressure-sensitive adhesive layer. The conductive adhesive tape according to claim 1, wherein the conductive adhesive tape contains an aggregate.