JP2003064339A - Adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an adhesive used for flat cables and the like to have strong adhesiveness and good tracking resistance. SOLUTION: The adhesive consisting of 75-95 pts.wt. polyester resin A having -70 to 10 deg.C glass transition temperature and 5,000-40,000 molecular weight and 5-25 pts.wt. polyester B having 50 to 100 deg.C glass transition temperature and 5,000-40,000 molecular weight is used to the adhesive layer 2 of an adhesive film 3 of a flat cable and the like. A flame retardant containing no halogens can be added to impart good flame retardance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive used for flat cables, flexible printed boards and the like.

[0002]

2. Description of the Related Art A flat cable having a structure in which a plurality of line-shaped conductors are covered with two adhesive films each having an adhesive layer formed on a base film is known. Such flat cables are widely used for internal wiring of computer equipment and high-density mounted AV equipment.

By the way, in such a flat cable, since a film made of a polyester resin such as polyethylene terephthalate is often used as a base film, a polyester resin is used as an adhesive constituting the adhesive layer. Mainly used is mainly.

In the adhesive containing the polyester resin as a main component, a polyester resin having a low glass transition temperature, for example, 10 ° C. or lower is used in order to enhance the adhesive force to the base film. However, an adhesive containing a polyester resin having a low glass transition temperature as a main component is inferior in blocking resistance, and a phenomenon called "adhesive residue" adheres to the back surface of the base film.

Further, the flat cable is required to have good flame retardancy in its constituent materials from the viewpoint of disaster prevention, and the adhesive layer thereof is also required to have flame retardancy. Therefore, as an adhesive forming the adhesive layer, a mixture of a halogen-based flame retardant such as decabromodiphenyl ether has been investigated.

However, with an adhesive containing a halogen-based flame retardant, a harmful halogen-containing gas is generated when a flat cable or the like using this adhesive is disposed of by incineration, and therefore its use must be avoided. There is a drawback to say no.

[0007]

Therefore, an object of the present invention is to obtain an adhesive used for a flat cable or the like, which has a high adhesive force to a base film and the like and is also excellent in blocking resistance. In addition, it is non-halogen and has sufficient flame retardancy.

[0008]

To solve these problems, the adhesive of the present invention has a glass transition temperature of -70 to 10 ° C.
Polyester resin A of 75 to 95 parts by weight and polyester resin B having a glass transition temperature of 50 to 100 ° C. of 5 to 25 parts by weight. Further, a non-halogen flame retardant is added to this. Further, the flat cable of the present invention uses the above adhesive in its adhesive layer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the embodiments thereof. FIG. 1 shows an example of the flat cable of the present invention. In the figure, reference numeral 1 indicates a base film. The substrate film 1 is a film having a thickness of 10 to 200 μm and made of a plastic such as saturated polyester such as polyethylene terephthalate or polyethylene naphthalate, polyimide, polyphenylene sulfide, polyethylene, polypropylene or polyamide. Among these plastic films, polyethylene terephthalate film is preferable in terms of electrical characteristics, mechanical characteristics, cost, and the like.

An adhesive layer 2 having a thickness of 15 to 100 μm is formed on one surface of the base film 1 to form an adhesive film 3. The two adhesive films 3 are laminated so that the adhesive layers 2 and 2 face each other, and a plurality of flat rectangular conductors 4 and 4 are sandwiched between them to be bonded to each other. The flat cable of is configured.

As an adhesive for forming the adhesive layer 2 of the adhesive film 3, an adhesive containing polyester resin A and polyester resin B as essential components or an adhesive containing a non-halogen flame retardant added thereto is used. There is.

The polyester resin A is a polyester resin having a glass transition temperature of -70 to 10 ° C and preferably a molecular weight of 5,000 to 40,000. The polyester resin B has a glass transition temperature of 50 to 100 ° C., and preferably has a molecular weight of 500.
It refers to a polyester resin of 0 to 40,000. The molecular weight in the present invention is expressed as a weight average molecular weight.

Examples of the polyester resin here include acid components such as terephthalic acid, isophthalic acid, diphenylcarboxylic acid, adipic acid and sebacic acid, and ethylene glycol, 1,4-butanediol, 1,4-dicyclohexanediene. Methylol, various saturated polyesters obtained by known polycondensation method using alcohol components such as dialcohols such as diethylene glycol,
Saturated copolyester is used.

The polyester resin has a glass transition temperature of 1 for the acid component and 1 for the alcohol component, respectively.
By combining more than one species, this can be
It can be adjusted to 10 ° C or in the range of 50 to 100 ° C. Further, its molecular weight is adjusted to 5,000 to 40,000 by appropriately adjusting various polymerization conditions during the condensation polymerization reaction of an acid component and an alcohol component, for example, polymerization temperature, polymerization time, polymerization pressure, a polymerization catalyst and the like. Can be set to a range.

In this polyester resin A, when the glass transition temperature is less than -70 ° C, the blocking property deteriorates,
If the temperature exceeds 10 ° C, the adhesive strength will decrease. In the polyester resin B, when the glass transition temperature is less than 50 ° C., the blocking property deteriorates, and when it exceeds 100 ° C., the adhesive strength decreases.

Further, the blending amount of the polyester resin A and the polyester resin B is such that the polyester resin A is 75 to 9
5 parts by weight, and the polyester resin B is 5 to 25 parts by weight. If the amount of the polyester resin A is less than 75 parts by weight, the adhesive strength will be reduced, and if it exceeds 95 parts by weight, the blocking property will be deteriorated.

In the adhesive of the present invention, in addition to the above polyester resin A and polyester resin B, a non-halogen flame retardant can be added to impart flame retardancy. As the non-halogen flame retardant, a nitrogen-containing organic flame retardant, a metal hydroxide, a phosphorus flame retardant, or the like is used.

The nitrogen-containing organic flame retardant is a non-halogen flame retardant and does not reduce the electric resistance of the adhesive layer. Specific examples of the nitrogen-containing organic flame retardant include:
One or a mixture of two or more of cyanuric acid triamide, cyanuric acid diamide, cyanuric acid monoamide, melam, melamine cyanurate, melamine resin, homoguanamine, benzoguanamine, acetoguanamine and the like can be mentioned.

Among these, polyester resins A and B
Melamine cyanurate is particularly preferable from the viewpoints of dispersibility, mixability, adhesiveness and the like. The nitrogen-containing organic flame retardant is added in an amount of 10 to 100 parts by weight, based on 100 parts by weight of the total amount of the two polyester resins A and B.
If it is less than 0 parts by weight, the flame retardancy is insufficient, and if it exceeds 100 parts by weight, the adhesive strength and mechanical properties are deteriorated.

The metal hydroxides include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, etc.
Phosphorus flame retardants include ammonium polyphosphate, red phosphorus,
Melamine polyphosphate or the like is used. Among these, aluminum hydroxide, magnesium hydroxide and the like are preferable because they have a particularly high flame retarding effect.

The amount of the metal hydroxide or phosphorus flame retardant added is 0 to 50 parts by weight based on 100 parts by weight of the total amount of the polyester resins A and B. If the amount exceeds 50 parts by weight, the adhesive strength is increased. descend. These non-halogen flame retardants are
Depending on the required flame retardancy, it is not necessary to add it,
The metal hydroxide also functions as an inorganic filler, enhances the rigidity of the adhesive layer, and consequently improves the adhesive strength, so it is preferable to add it in a range that does not become excessive.

The adhesive of the present invention may further contain various additives such as organic solvents, within the range not impairing the effects of the present invention.
An antioxidant, a metal corrosion inhibitor, a colorant, various coupling agents, a cross-linking agent, a cross-linking aid, a filler, and an antistatic agent may be appropriately added. As the organic solvent, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, and aromatics such as toluene are used.

The adhesive of the present invention comprises 100 parts by weight of the total amount of polyester resins A and B, or 10 to 100 parts by weight of a nitrogen-containing organic flame retardant, and 0 to 100 parts of a metal hydroxide or a phosphorus flame retardant. It can be produced by uniformly mixing 50 parts by weight and other additive components as necessary. Further, as the form of the adhesive of the present invention, a solution, a paste, a form of pellets, or the like can be used. To form an adhesive layer of a flat cable, as a solution type,
In addition to being used by applying it to a base film, pellets are generally extruded from an extruder onto the base film to form a film for use.

Further, the flat cable of the present invention uses the adhesive film formed as described above, sandwiches the conductor, and pressurizes it with a pressure roll, a pressure press, etc., at the same time, at a temperature of 80 It is produced by heating to ~ 200 ° C. Generally, a method of using a heating and pressing roll and continuously adhering is widely used in terms of workability and the like.

In such an adhesive, the base polymer has a glass transition temperature of −70 to 10 ° C. and a molecular weight of 5
5,000-40,000 polyester resin A 75-95 parts by weight, glass transition temperature 50-100 ° C, molecular weight 500
Since a blend polymer of 0 to 40,000 with 5 to 25 parts by weight of the polyester resin B is used, a high adhesive force can be obtained and blocking resistance is excellent.

In general, in the base polymer forming the adhesive, as the glass transition temperature becomes lower, the adhesive strength becomes higher, but the molecular cohesive force is lowered and the blocking resistance is lowered. On the other hand, as the glass transition temperature increases, the adhesive force decreases, but the molecular cohesive force increases, and the blocking resistance improves.

In the present invention, therefore, the polyester resin A having a low glass transition temperature and the polyester resin B having a high glass transition temperature are mixed and used at an appropriate composition ratio.
It has a good balance of both characteristics. Further, in the case of adding a halogen-free flame retardant, in addition to these effects, high flame retardancy is obtained. Further, since it is non-halogen, no harmful halogen-containing gas is generated even if it is incinerated.

Further, in the flat cable, good adhesive strength is exhibited, and when a non-halogen flame retardant is added, it has high flame retardancy, and harmful halogen-containing gas is generated even when incinerated. There is nothing to do. Therefore, this flat cable can be used for wiring of computer equipment and the like which is required to have high adhesiveness and good flame retardancy.

Specific examples will be shown below. The compositions having the compounding compositions (parts by weight) shown in Tables 1 and 2 were dissolved in a mixed solvent consisting of 1 part by volume of methyl ethyl ketone and 4 parts by volume of toluene to produce a solution adhesive having a resin content of 40 wt%. This solvent-type adhesive was applied onto a polyethylene terephthalate film having a thickness of 25 μm with a bar coater and dried to form an adhesive layer having a thickness of 35 μm to prepare an adhesive film.

With respect to the adhesive film thus obtained, the adhesive strength, blocking resistance, breaking load, tensile elongation and oxygen index were measured. As for the adhesive strength, the two adhesive films were bonded at a bonding speed of 0.3 m / min, a temperature of 160 ° C. and a pressure of 0.5 MPa, and the T-shaped peeling strength of this material was measured. The blocking resistance was evaluated as x when the adhesive film was wound inside the adhesive layer and the adhesive film was adhered to the back surface of the substrate film when the adhesive film was unwound, and when the adhesive film was not adhered was evaluated as o.

The breaking load and the tensile elongation are 10 mm in width,
The central portion of the adhesive film having a length of 200 mm was marked at intervals of 50 mm, and this was pulled at a speed of 200 mm / min to measure the strength and elongation at break of the film. The oxygen index was measured by a flame retardant oxygen index measuring device.

In Tables 1 and 2, "polyester resin 1" means a polyester resin having a glass transition point of 3 ° C and a molecular weight of 25,000, and "polyester resin 2" means a polyester resin having a glass transition point of 65 ° C and a molecular weight of 15,000. .

“Polyester resin 3” is a polyester resin having a glass transition point of 3 ° C. and a molecular weight of 4000, and “polyester resin 4” is a glass transition point of 65 ° C. and a molecular weight of 400.
The polyester resin of 0 is shown.

"Polyester resin 5" is a polyester resin having a glass transition point of 3 ° C. and a molecular weight of 50,000, and "polyester resin 6" is a glass transition point of 65 ° C. and a molecular weight of 50.
000 polyester resins are shown.

"Polyester resin 7" is a polyester resin having a glass transition point of -75 ° C. and a molecular weight of 25,000.
“Polyester resin 8” refers to a polyester resin having a glass transition temperature of 105 ° C. and a molecular weight of 15,000. The results are shown in Table 1.
And shown in Table 2.

[0036]

[Table 1]

[0037]

[Table 2]

From the results shown in Tables 1 and 2, the glass transition temperature -7
75 to 95 parts by weight of polyester resin A having a molecular weight of 5,000 to 40,000 and a glass transition temperature of 50 to 1
It can be seen that the one containing 5 to 25 parts by weight of the polyester resin B having a molecular weight of 5,000 to 40,000 at 00 ° C. exhibits good adhesive force and is excellent in blocking resistance.
Further, it can be seen that the one to which the non-halogen flame retardant is added has high flame retardancy.

[0039]

As described above, the adhesive of the present invention has a glass transition temperature of -70 to 10 ° C and a molecular weight of 5,000 to 5,000.
40-000 polyester resin A 75 to 95 parts by weight,
Glass transition temperature 50 to 100 ° C, molecular weight 5,000 to 40
Since it contains 5 to 25 parts by weight of 000 polyester resin B, it exhibits good adhesive strength and is excellent in blocking resistance. In addition, when a non-halogen flame retardant is added, the flame retardant has higher flame retardancy, and no harmful halogen-containing gas is generated even when incinerated.

Further, in the flat cable of the present invention, therefore, a good adhesive force is exhibited, durability becomes high, and no inconvenience due to tracking property occurs during manufacturing work. Further, the one using an adhesive containing a halogen-free flame retardant has high flame retardancy. Further, since it is non-halogen, no harmful halogen-containing gas is generated even if it is incinerated. Therefore, this flat cable can be suitably used for wiring of computer equipment or the like which requires high adhesive strength and good flame retardancy.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a flat cable according to the present invention.

[Explanation of symbols]

2 ... Adhesive layer.

Continued front page    F-term (reference) 4J004 AA15 AA17 AA18 AB03 CA04                       CA06 CC02 FA05                 4J040 EB132 ED021 ED041 ED051                       HA131 HA156 HA266 HC10                       HC11 HC12 KA36 LA02 LA08                       NA19                 5G311 CA01 CB01 CD03

Claims (3)

[Claims] 1. A polyester resin A having a glass transition temperature of −70 to 10 ° C., and a glass transition temperature of 50 to 75 parts by weight.
An adhesive containing 5 to 25 parts by weight of a polyester resin B at 100 ° C. 2. The adhesive according to claim 1, further comprising a halogen-free flame retardant. 3. A flat cable obtained by sandwiching and bonding a conductor with an adhesive film having an adhesive layer formed on the surface of a base film, wherein the adhesive layer comprises the adhesive according to claim 1 or 2. .