JP2009114412A - Conductive flame-retardant adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive flame-retardant adhesive tape which exhibits excellent flame retardance without using a halogen-based flame retarder, has electrical conductivity in the thickness direction of its base material, and whose flame retardance is hardly deteriorated over time. <P>SOLUTION: The conductive flame-retardant adhesive tape is obtained by providing an adhesive layer on at least one surface of a base material formed from an organic fiber having electrical conductivity. The adhesive layer is constituted of an adhesive, a flame retarder, and a conductive material. The flame retarder is composed of a nitrogen-containing phosphate compound (A) and an organic phosphate compound (B). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a flame retardant pressure-sensitive adhesive tape having excellent flame retardancy, electrical conductivity in the thickness direction of an adhesive substrate, and adhesion without using a halogen-based flame retardant, and flame retardant over time The present invention relates to a flame retardant pressure-sensitive adhesive tape having conductivity with little deterioration in property.

  In recent years, in the electric and electronic fields, high flame resistance has been demanded for electronic components and the like constituting the same, and in many cases, UL standards have been demanded. Yes. For example, UL 510 is an UL standard for electrical insulating tapes used for electronic parts and the like, and high flame retardant properties that pass this standard are required. The same applies to other flame retardant standards.

  Halogen flame retardants have been used in the past to impart flame retardancy to this adhesive tape, but halogen flame retardants generate halogen gases, which can cause corrosion of equipment and the like. For this reason, studies on non-halogen flame retardants are in progress. For example, Patent Document 1 proposes a highly flame-retardant flame-retardant adhesive tape by using ammonium polyphosphate as a flame retardant and defining its particle size and specific surface area. However, it is not a tape having conductivity in the thickness direction of the base material, and according to our research, it has been found that there is a problem that the flame retardancy decreases with time.

  On the other hand, Patent Document 2 proposes an electromagnetic wave shielding material having conductivity and flame retardancy in the thickness direction of the base material, and an adhesive in which a conductive filler and a flame retardant are blended in an organic fiber fabric subjected to electroless plating. It is described that a layer is provided. However, according to our research, it has been found that depending on the type of flame retardant, there is a problem that the conductivity in the thickness direction becomes insufficient or the adhesiveness is lowered. Moreover, it is difficult to apply the electromagnetic shielding material as an adhesive tape as it is for such reasons.

  Therefore, today, there is a demand for conductive flame-retardant adhesive tapes for noise countermeasures such as connector terminal parts of electronic devices, shields for cables, ground reinforcement, etc. In fact, no tape has been developed that simultaneously satisfies the stable flame retardancy, adhesiveness, and conductivity in the thickness direction of the substrate.

JP-A-11-1669 JP 2004-235393 A

  The object of the present invention is to provide a flame retardant having excellent flame retardancy and electrical conductivity in the thickness direction of the adhesive substrate without using a halogen-based flame retardant, and having little decrease in flame retardance over time. An object is to provide an adhesive tape.

  The present inventor examined the flame retardant contained in the adhesive layer of the adhesive tape having conductivity, and when different phosphorus-based flame retardants were contained in the adhesive layer at a specific blending ratio, the adhesive property and the conductivity in the thickness direction were determined. In addition to exhibiting excellent flame retardancy without deterioration, the flame retardance does not decrease over time even when the adhesive tape is left under high temperature and high humidity, and stable high flame retardancy is maintained. I found out that

  Thus, according to the present invention, there is provided a conductive flame retardant pressure-sensitive adhesive tape in which an adhesive layer is provided on at least one side of a base material made of conductive organic fiber, and the adhesive layer is a pressure-sensitive adhesive, a flame retardant, a conductive material. There is provided a flame retardant pressure-sensitive adhesive tape having electrical conductivity, characterized in that the flame retardant comprises a nitrogen-containing phosphate compound (A) and an organic phosphate compound (B).

  By using the conductive flame retardant adhesive tape of the present invention, there is no deterioration in flame retardant with time, and the tape has excellent conductivity and adhesiveness, and can exhibit excellent effects in shielding and grounding.

  Hereinafter, the present invention will be described in detail. If the fiber which comprises the base material (henceforth a conductive fabric) comprised from the organic fiber which has the electroconductivity of this invention is an organic fiber, there will be no limitation in particular, and heat resistance and a flame retardance are considered. In this case, it is preferable to use an aramid fiber, a polybenzimidazole fiber, a polybenzoxazole fiber, a modacrylic fiber, or a polytetrafluoroethylene fiber. Polyester fibers such as polyethylene terephthalate fiber, polyethylene naphthalate fiber, polytrimethylene terephthalate fiber, acrylic fiber, nylon fiber, and the like can also be used.

  Further, for the above-mentioned organic fibers, it is preferable to perform etching to impart unevenness to the fiber surface or conditioner treatment with a surfactant or the like in order to improve the adhesion between the metal film and the fibers. .

  Although the single fiber fineness of the organic fiber is not particularly limited, those having a range of 0.33 to 5.56 dtex are preferably used. When the single fiber fineness is less than 0.33 dtex, handling of the fabric may be difficult. On the other hand, when the single fiber fineness exceeds 5.56 dtex, the contact object and the conductive fabric are in contact with each other. In some cases, the metal film is cracked due to the high stress at the time.

The organic fiber is a long fiber or short fiber, and a fiber yarn such as a composite fiber, a processed yarn, or a spun yarn, and a woven fabric, a knitted fabric, or a non-woven fabric that is a known fiber assembly using the fiber yarn. It is used in the form of a fabric such as.
At this time, plain weave, twill, satin weave, oblique weave, and these changed weaves are preferably used, and warp knitted and weft knitted fabrics can be used as the knitted fabric.

  When the fabric is a non-woven fabric, a non-woven fabric composed of long fibers or short fibers is used, and these non-woven fabrics are card web, needle punch, spunbond, air raid, or a composite containing two or more of these methods. It is produced by a dry method produced by a method, or a wet method in which a fiber is dispersed in water to form a slurry.

  When the fabric is a non-woven fabric, it is preferable to take measures for preventing fluff by resin processing. In applications where fluff due to friction with a contact object is strictly prohibited, it is preferable to use a long-fiber fabric instead of a non-woven fabric.

  The thickness of the conductive fabric is not particularly limited and can be set to a preferred thickness depending on the intended use, but considering the flexibility as a tape, it is 50 to 200 μm, more preferably 75 to 175 μm. When the thickness is less than 50 μm, sufficient mechanical properties as a tape cannot be obtained. Moreover, when thickness exceeds 200 micrometers, the softness | flexibility as a tape will be lose | eliminated.

The basis weight of the conductive fabric is not particularly limited, and can be a preferable basis weight depending on the intended use. However, in consideration of handling property and flexibility as a tape, 50 to 200 g / m ² , more preferably 70 to 150 g / m ^2. It is. When the basis weight is less than 50 g / m ² , sufficient mechanical properties as a tape cannot be obtained. Moreover, when a fabric weight exceeds 200 m < ² >, the flexibility as a tape will be lost.

  In the present invention, it is necessary that the organic fiber has conductivity. Here, the organic fiber has conductivity means that a metal film or the like capable of removing static electricity is formed on the surface of the organic fiber or the aggregate surface of the fiber.

As a method for forming a metal film on the surface of the organic fiber or the aggregate of the fibers, a conventionally known method is used, and a method of performing electroless plating, electroplating, metal vapor deposition, sputtering processing or the like on the surface of the fiber or fabric However, a method of forming a metal film on the surface of the fabric by electroless plating is particularly preferable.
Alternatively, an organic fiber having a metal film formed on its surface in advance may be used as a fiber yarn, and the fiber yarn may be used to form a fabric such as a woven fabric or a knitted fabric.

  Examples of the metal forming the film include gold, silver, copper, zinc, nickel, tin, and alloys thereof, and among them, low-cost and versatile copper is preferable. Further, the layer formed of these metals may be a single layer or a multilayer of two or more layers.

  An example of a method for forming a copper film by electroless plating will be described in more detail. First, the fabric is subjected to a scouring process by a known method to remove the glue and oil on the fabric surface. Next, after reducing the weight by immersing it in an alkaline solution as necessary, the scoured fabric is adsorbed with palladium that is the core of electroless plating, activated, and then immersed in a copper plating bath. Then, a copper film is formed on the fabric surface.

The thickness of the copper film formed by the above treatment may be in the range of 0.1 to 2.0 μm on average. If the thickness of the film is larger than the above range, the metal film is likely to fall off, which is not preferable.
In order to prevent rust, a metal film having good corrosion resistance such as nickel can be further formed on the metal film formed by the above method, or a rust inhibitor can be applied.

The pressure-sensitive adhesive tape of the present invention is a pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer on at least one surface of the conductive fabric, and the pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive, a conductive agent, and a flame retardant.
Although the adhesive which forms an adhesion layer is not specifically limited, The well-known acrylic adhesive and rubber adhesive which are generally used are used as a base polymer. For example, acrylic adhesives include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, nonyl methacrylate, and methacrylate. Mainly composed of methacrylic acid ester monomers such as isononyl acid, monomers containing functional groups such as methacrylic acid, crotonic acid, fumaric acid, itaconic acid, maleic anhydride, vinyl acetate, acrylonitrile, styrene, methacrylic acid It is a publicly known acrylic pressure-sensitive adhesive obtained by copolymerizing 2-hydroxyethyl, 2-methylolethylacrylamide or the like as necessary.

  The rubber-based pressure-sensitive adhesive is not particularly limited. For example, an elastomer component such as natural rubber, styrene butadiene rubber, butyl rubber, isoprene rubber, butadiene rubber, and styrene isoprene block copolymer is used alone or in combination of two or more. In contrast, rosin resin, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, copolymer petroleum resin, alicyclic petroleum resin, coumarone / indene resin, pure monomer resin, phenol resin It is a known rubber-based pressure-sensitive adhesive made by mixing xylene resin and the like.

  In this invention, it is important that the flame retardant which comprises an adhesion layer consists of two types, a nitrogen-containing phosphate compound (A) and an organic phosphate compound (B). The present inventors have found that when such a combination of phosphorus compounds is used, stable flame retardancy can be maintained without decreasing flame retardance over time even under high temperature and high humidity. Furthermore, it has been found that when such a combination of flame retardants is selected, there is little decrease in adhesion and electrical conductivity in the thickness direction.

Examples of the nitrogen-containing phosphate compound (A) include ammonium polyphosphate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, melamine polyphosphate, melam polyphosphate, melem polyphosphate, melon polyphosphate, phosphate ester amide Preferred examples include guanidine phosphate. These nitrogen-containing phosphorus flame retardants (A) may be microencapsulated.
On the other hand, a specific example of the organic phosphate compound (B) is preferably “PEKOFLAM STC POWDER (trade name)” (manufactured by Clariant Japan Co., Ltd.).

  The compounding quantity of the flame retardant in an adhesion layer is 60-200 parts with respect to 100 parts of adhesives, More preferably, it is 100-150 parts. When the blending amount of the flame retardant is less than 60 parts, it is difficult to pass the UL 510 flame retardant test. Further, when the amount of the flame retardant exceeds 200 parts, the flame retardant in the pressure-sensitive adhesive causes secondary aggregation. For example, when a pressure-sensitive adhesive containing a flame retardant is coated on a conductive fabric, warps are generated. Adhesive performance is reduced.

  The blending ratio of the nitrogen-containing phosphate compound (A) and the organic phosphate compound (B) may be arbitrarily adjusted between (A) :( B) = 95: 5-40: 60 based on the weight. However, More preferably, it is (A) :( B) = 90: 10-50: 50. When the organic phosphate compound (B) is less than 5% by weight, decomposition of the nitrogen-containing phosphate compound (A) over time cannot be suppressed by the organic phosphate compound (B), and flame retardancy Gradually decreases and does not pass the UL510 combustion test. Further, when the organic phosphate compound (B) exceeds 60% by weight, secondary aggregation is likely to occur. For example, when a pressure-sensitive adhesive containing a flame retardant is coated on a conductive fabric, warps are generated, There exists a tendency for adhesive performance to fall.

  The conductive agent constituting the adhesive layer is added to provide conductivity in the thickness direction. Examples of the conductive agent include copper, nickel, silver, gold and / or alloy particles of these metals, conductive carbon particles, and the like, and a material obtained by coating an inorganic substance with copper, nickel, silver, or the like is also used. Moreover, the compounding quantity of a electrically conductive agent becomes like this. Preferably it is 2-30 parts with respect to 100 parts of adhesives, More preferably, it is 3-20 parts. If the amount of the conductive agent is less than 2 parts, it tends to be difficult to obtain sufficient conductivity in the thickness direction. Moreover, when the amount of the conductive agent exceeds 30 parts, the flame retardancy tends to decrease.

  Further, in the adhesive layer, various additives such as an antioxidant, a weathering agent, a softening agent, a stabilizer, a filler, a bulking agent, and a reinforcing agent are added as necessary within a range not impairing the flame retardant effect of the present invention. An agent can be added 1 type or in combination of 2 or more types.

  Examples of the method for producing the pressure-sensitive adhesive tape of the present invention include the following methods. That is, it is dispersed in a polymer that is an adhesive for the flame retardant and the conductive agent. At this time, as a dispersion method, in addition to a generally known mechanical kneading dispersion method, a known method such as a solvent dispersion method or an ultrasonic dispersion method can be used as necessary. The coating method of the flame retardant adhesive conductive agent composition thus formed is not particularly limited. For example, one layer on at least one surface of the conductive fabric using a roll coater or a reverse coater, or Two or more layers are applied, and the tape of the present invention is obtained by heating as necessary. Further, a sheet-like or film-like adhesive layer can be laminated on the conductive fabric.

  The thickness of the adhesive layer is not particularly limited, but is preferably 5 to 70 μm, more preferably 10 to 50 μm when considering use as a tape. If it is less than 5 μm, the flame retardancy is insufficient and it tends to be difficult to pass the UL510 combustion test. Moreover, when it exceeds 70 micrometers, there exists a possibility that the electroconductive performance of the thickness direction may fall.

Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, “parts” represents parts by weight. The physical properties used in the examples were measured by the following methods.
(1) Flame resistance evaluation (flammability test)
A combustion test was performed according to the UL510 combustion test. In addition, in order to confirm the flame retardancy immediately after sample preparation and over time, the combustion test was conducted after leaving the sample to stand at 40 ° C. and 60% RH for one month and then drying it at 50 ° C. for 30 minutes. Went.
(2) Conductivity in the thickness direction Measured according to JIS K 7194, and 0.1Ω or less was accepted.
(3) Adhesiveness Measured according to JIS L 1096, the peel strength was judged as adhesive strength, and the adhesive strength was 9N or more and passed.

[Example 1]
A 2/1 twill woven fabric having a weaving density of 140 yarns / inch and a weft density of 105 yarns / inch was woven using 56 dtex polyester long fibers having 36 filaments (“Silfil” manufactured by Teijin Fibers Limited).
After scouring the fabric, electroless plating is applied to form a 0.7 mm thick copper metal film on the surface of the constituent fibers, and then the copper metal film is further thickened by electroless plating. A nickel metal film having a thickness of 0.2 mm was formed.

  A flame retardant adhesive SK Dyne 1795G (manufactured by Soken Chemical Co., Ltd.) in which an acrylic adhesive and ammonium polyphosphate, which is a nitrogen-containing phosphate compound (A), were blended was used. Hereinafter, the blending amount of other agents is shown with 100 parts of the acrylic pressure-sensitive adhesive blended in SK Dyne 1795G. In addition, the compounding quantity of the nitrogen containing phosphate compound (A) (ammonium polyphosphate) in said SK dyne 1795G is 100 parts with respect to 100 parts of acrylic adhesives.

  SK Dyne 1795G has 1 part of catalyst, 25 parts of toluene, 10 parts of “PEKOFLAM STC POWDER” made by Clariant Japan Co., which is an organic phosphate compound (B), and an average particle size of 35 μm per 100 parts of acrylic adhesive. 5 parts of a filler-like conductive agent (nickel powder: powder of glass beads coated with silver (glass beads / silver weight ratio 92/8) = 4: 6 (weight ratio)) were mixed and kneaded with a kneader. . Thereafter, coating was carried out by a floating knife method while bringing the blade into contact with the back surface of the conductive fabric, thereby forming an adhesive layer. At that time, the coating thickness of the adhesive layer was set to 20 μm. And it dried for 3 minutes in oven in 130 degreeC atmosphere. The results are shown in Table 1.

[Example 2]
Example 2 was the same as Example 1 except that the amount of the organophosphate compound (B) was 40 parts and the coating thickness with a floating knife was 25 μm. The results are shown in Table 1.

[Example 3]
Example 3 was the same as Example 1 except that the blending amount of the conductive agent was 20 parts and the coating thickness with a floating knife was 30 μm. The results are shown in Table 1.

[Example 4]
Example 4 was the same as Example 1 except that the coating thickness with a floating knife was 10 μm. The results are shown in Table 1.

[Comparative Example 1]
The same as Example 1 except that the organic phosphate compound (B) was not used. The results are shown in Table 1.

[Comparative Example 2]
Instead of 10 parts of the organic phosphate compound (B), the same procedure as in Example 1 was carried out except that 10 parts of a phosphate ester flame retardant (“phoscon FR-4936” manufactured by Meisei Chemical Co., Ltd.) was used. The results are shown in Table 1.

[Comparative Example 3]
Instead of 100 parts of the flame retardant adhesive “SK Dyne 1795G”, 100 parts of an acrylic adhesive “SK Dyne 1717” (manufactured by Soken Chemical Co., Ltd.) containing no flame retardant is used, and is an organic phosphate compound (B). The same as Example 1 except that the blending amount of “PEKOFLAM STC POWDER” manufactured by Clariant Japan was changed from 10 parts to 50 parts. The results are shown in Table 1.

  By using the conductive flame-retardant adhesive tape of the present invention, the flame retardancy does not deteriorate with time, and the tape has excellent conductivity and adhesiveness, and can exhibit excellent effects in shielding and grounding.

Claims (5)

  A conductive flame retardant adhesive tape having an adhesive layer provided on at least one surface of a base material made of organic fibers having conductivity, the adhesive layer comprising an adhesive, a flame retardant, and a conductive agent, and A flame retardant adhesive tape having conductivity, wherein the flame retardant comprises a nitrogen-containing phosphate compound (A) and an organic phosphate compound (B).   The conductive ratio according to claim 1, wherein the compounding ratio of the nitrogen-containing phosphate compound (A) and the organic phosphate compound (B) is (A) :( B) = 95: 5-40: 60 on the basis of weight. Flame retardant adhesive tape.   The flame retardant adhesive tape having conductivity according to claim 1, wherein the organic fiber having conductivity is an organic fiber having a metal surface plated with metal.   The flame retardant adhesive tape having conductivity according to any one of claims 1 to 3, wherein the organic fiber is a polyester fiber.   The evaluation in the UL510 combustion test and the evaluation in the UL510 combustion test after leaving the conductive flame-retardant adhesive tape to stand at 40 ° C. and 60% RH for one month and drying it at 50 ° C. for 30 minutes The flame-retardant pressure-sensitive adhesive tape having conductivity according to any one of claims 1 to 4.