JP2015101696A - Polyester adhesive, adhesive for forming flat cable, and flat cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester adhesive which is excellent not only in adhesion to a resin substrate but also in adhesion to non-resin substrates such as metal, wood, paper, and leather, is easily dissolved in an organic solvent, and is excellent in solution stability.SOLUTION: The polyester adhesive contains a polyester resin comprising a polycarboxylic acid component (A) and a polyol component (B). The polycarboxylic acid component (A) contains at least terephthalic acid and isophthalic acid. The polyol component (B) contains 1,6-hexanediol, 1,4-butanediol, and ethylene glycol. The content of adipic acid which may be contained in the polycarboxylic acid component (A) is 10 mol% or less. The content of 1,6-hexanediol is 35 mol% or more based on the whole polyol component (B).

Description

  The present invention relates to a polyester-based adhesive, an adhesive for a flat cable, and a flat cable. More specifically, the present invention is excellent not only in adhesiveness with a resin base material but also in non-resin base materials such as metal, wood, paper, leather, etc., and easily dissolved in an organic solvent. The present invention relates to a polyester adhesive having excellent stability. Further, the flat cable forming adhesive is used as an adhesive in which the polyester adhesive is interposed between the resin base material and the conductor in the flat cable, and the flat cable forming adhesive is provided between the resin base material and the conductor. It is related with the flat cable interposed in.

  In recent years, in computers, liquid crystal display devices, mobile phones, printers, automobiles, home appliances, copiers, and other various electrical appliances, labor saving and miswiring of wiring work has been performed in response to the increasing complexity of internal wiring. For prevention, flat cables have been widely used.

  A flat cable generally includes an insulating film in which an adhesive layer is laminated on a base material (insulating layer) in the form of a film (including the concept of a tape and a sheet, the same shall apply hereinafter). A plurality of conductors are juxtaposed between the adhesive layers, the adhesive layers are overlapped with each other, the conductors are sandwiched, and heat-sealed. That is, the flat cable has a structure in which a conductor is included in the adhesive layer and insulating layers are provided on both outer surfaces of the cable. Examples of the adhesive used for forming the flat cable include a polyester-based adhesive disclosed in Patent Document 1.

  Polyester adhesives can be broadly classified into solventless hot-melt adhesives and solvent-based solvent-based adhesives. In recent years, solvent-free hot-melt adhesives tend to be used frequently due to pollution problems, but due to reasons such as thin film coating and ease of work, demand for solvent-based adhesives has increased. The current situation is that solvent-based adhesives are widely used for applications such as adhesives for dry lamination between resin substrates or between non-resin substrates such as metals, and coating agents for various materials. It is.

  The solvent-based adhesive is generally obtained by dissolving a polyester-based resin in a general-purpose solvent such as toluene or methyl ethyl ketone. Of the polyester resins, crystalline polyester resins have excellent cohesive strength and good adhesion, but are generally poorly soluble in solvents. Conversely, an amorphous polyester resin is easily soluble in a solvent, but generally has poor cohesive strength. That is, it is very difficult to obtain a solvent-based polyester adhesive that has excellent cohesive strength and is easily soluble in a solvent.

In order to solve such problems, for example, Patent Document 2 discloses an adhesive composition in which a saturated polyester resin obtained by reacting an acid component having a specific composition and a glycol component having a specific composition is dissolved in a mixed solvent having a specific composition. It is disclosed.
According to this adhesive composition, the solvent solubility of the crystalline polyester resin and the stability after dissolution can be improved, so that the adhesive force to the resin substrate can be improved.

JP-A-6-320692 JP-A-6-184515

However, since the adhesive composition disclosed in Patent Document 2 has low adhesion to non-resin substrates such as metal substrates, flat cable formation requiring high adhesion to both resin substrates and conductors is required. It was hard to say that it was suitable for adhesives.
Accordingly, the present invention has been made in view of such circumstances, and is excellent not only in adhesiveness with a resin base material but also in adhesiveness with a non-resin base material such as metal, wood, paper, leather, and the like. An object of the present invention is to provide a polyester-based adhesive that is easily dissolved in an organic solvent and excellent in solution stability.
Moreover, this polyester-based adhesive is used as an adhesive that is interposed between the resin base material and the conductor in the flat cable, and the flat cable forming adhesive is used between the base material and the conductor. The object is to provide an intervening flat cable.

  However, the inventor of the present invention has a polyester-based resin composed of a polyvalent carboxylic acid component having a specific composition and a polyol component having a specific composition having excellent solubility in an organic solvent and stability after dissolution, It has been found that the above object is achieved with excellent adhesion to non-resin substrates such as metals.

  That is, the present invention is a polyester-based adhesive containing a polyester-based resin composed of a polyvalent carboxylic acid component (A) and a polyol component (B), wherein terephthalic acid and polyvalent carboxylic acid component (A) Adipic acid which contains at least isophthalic acid, contains 1,6-hexanediol, 1,4-butanediol and ethylene glycol as polyol component (B) and may be contained as polyvalent carboxylic acid component (A) Is a polyester-based adhesive characterized in that the content of 1,6-hexanediol is 35 mol% or more with respect to the entire polyol component (B).

  Moreover, this invention is an adhesive for flat cable formation characterized by using the polyester-type adhesive agent of this invention as an adhesive agent interposed between the resin base material and conductor in a flat cable.

  Furthermore, the present invention is a flat cable characterized in that the flat cable forming adhesive of the present invention is interposed between a resin base material and a conductor.

  The reason why the polyester adhesive of the present invention is excellent in solubility in an organic solvent and stability after dissolution is not clear, but the polyol component (B) containing a specific amount of 1,6-hexanediol and a polyvalent carboxylic acid. This is presumed to be because it contains a polyester-based resin composed of the acid component (A). Also, it is not clear why the polyester-based adhesive of the present invention is excellent in adhesion to non-resin base materials such as metals, but a polyvalent carboxylic acid containing terephthalic acid and isophthalic acid and containing adipic acid at a specific amount. It is presumed that this is because it contains a polyester-based resin composed of an acid component (A) and a polyol component (B) containing 1,4-butanediol and ethylene glycol.

  The polyester-based adhesive of the present invention is useful not only for adhesion between resin base materials such as polyethylene terephthalate (PET) but also for adhesion between non-resin base materials such as metal, wood, paper, leather, and resin base materials. Also useful. Moreover, the polyester-based adhesive of the present invention is excellent not only in adhesiveness but also in heat resistance and mechanical properties. Therefore, the polyester-based adhesive of the present invention is particularly useful as an adhesive for forming a flat cable for bonding a metal wiring as a conductor and a resin base material.

  The present invention will be described in detail below, but these show examples of desirable embodiments.

<Polyester adhesive>
The polyester-based adhesive of the present invention contains a polyester-based resin obtained by polymerizing a polyvalent carboxylic acid component (A) and a polyol component (B). First, the polyvalent carboxylic acid component (A) and the polyol component (B) will be described sequentially.

[Polyvalent carboxylic acid component (A)]
The polyvalent carboxylic acid component (A) used in the present invention contains at least terephthalic acid and isophthalic acid.
The content of terephthalic acid with respect to the entire polyvalent carboxylic acid component (A) is preferably 50 to 99 mol%, particularly preferably 60 to 95 mol%, more preferably 65 to 90 mol%. If the content of terephthalic acid is too small, the adhesive strength tends to decrease, and if too much, the solution stability tends to decrease.

  The content of isophthalic acid relative to the entire polyvalent carboxylic acid component (A) is preferably 1 to 50 mol%, particularly preferably 5 to 40 mol%, and more preferably 10 to 35 mol%. If the content of isophthalic acid is too small, the solution stability tends to decrease, and if it is too large, the melting point tends to decrease.

  The polyvalent carboxylic acid component (A) used in the present invention may contain adipic acid. The content of adipic acid relative to the entire polyvalent carboxylic acid component (A) is 10 mol% or less, preferably 5 mol% or less, particularly preferably 1 mol% or less, and even more preferably not contained. When there is too much content of adipic acid, there exists a tendency for the adhesive force to non-resin base materials, such as a metal, to fall.

The polyvalent carboxylic acid component (A) used in the present invention may further contain other polyvalent carboxylic acid in addition to the above polyvalent carboxylic acid.
Examples of other polyvalent carboxylic acids include aromatic dicarboxylic acids such as benzylmalonic acid, diphenic acid, and 4,4′-oxydibenzoic acid;
Malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, thiodipropionic acid, diglycol Aliphatic dicarboxylic acids such as acids;
Alicyclics such as 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, adamantanedicarboxylic acid, etc. Dicarboxylic acids;
Etc. One kind selected from these other polyvalent carboxylic acids may be used alone, or two or more kinds may be used in combination.
Moreover, the polyvalent carboxylic acid component (A) used in the present invention can use a small amount of trivalent or higher polyvalent carboxylic acid in addition to the above-mentioned various dicarboxylic acids. For example, trimellitic acid, pyromellitic acid, adamantanetricarboxylic acid, trimesic acid and the like can also be used.

[Polyol component (B)]
The polyol component (B) used in the present invention contains 1,6-hexanediol, 1,4-butanediol and ethylene glycol.
The content of 1,6-hexanediol with respect to the whole polyol component (B) is 35 mol% or more, preferably 35 to 90 mol%, particularly preferably 35 to 80 mol%, more preferably 35 to 70 mol%. It is. If the content of 1,6-hexanediol is too small, the solution stability tends to decrease, and if it is too large, the adhesive strength tends to decrease.

  The content of 1,4-butanediol with respect to the entire polyol component (B) is preferably 5 to 60 mol%, particularly preferably 10 to 60 mol%, and further preferably 20 to 60 mol%. If the content of 1,4-butanediol is too small, the melting point tends to decrease, and if too much, the solution stability tends to decrease.

  The content ratio (molar ratio) of 1,6-hexanediol and 1,4-butanediol is preferably 35:65 to 95: 5, particularly preferably 35:65 to 85:15, and more preferably 35:65. 75:25. If the content ratio of 1,6-hexanediol with respect to 1,4-butanediol is too high, the adhesive strength tends to decrease, and if too low, the solution stability tends to decrease.

  The content ratio (molar ratio) of 1,6-hexanediol and ethylene glycol is preferably 55:45 to 95: 5, particularly preferably 60:40 to 90:10, and more preferably 65:35 to 85:15. is there. When the content ratio of 1,6-hexanediol with respect to ethylene glycol is too high, the adhesive strength tends to be lowered, and when too low, the solution stability tends to be lowered.

  The content of ethylene glycol with respect to the entire polyol component (B) is preferably 5 to 30 mol%, particularly preferably 5 to 25 mol%, and still more preferably 10 to 25 mol%. If the ethylene glycol content is too small, the adhesive strength tends to decrease, and if it is too large, the melting point tends to decrease.

The polyol component (B) used in the present invention may further contain other polyols in addition to the above polyols.
As said other polyol, for example,
Diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, 3- Aliphatic diols such as methyl-1,5-pentanediol and 2,2,4-trimethyl-1,6-hexanediol;
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, 2,2,4,4-tetramethyl-1,3 -Alicyclic diols such as cyclobutanediol;
4,4'-thiodiphenol, 4,4'-methylenediphenol, bisphenol S, bisphenol A, 4,4'-dihydroxybiphenyl, o-, m- and p-dihydroxybenzene, 2,5-naphthalenediol and aromatic diols such as p-xylene diol;
Etc.
One kind selected from these other polyols may be used alone, or two or more kinds may be used in combination.

  In addition to the above-mentioned various polyols, the polyol component (B) used in the present invention is a trivalent or higher polyol, such as pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1 , 3,6-hexanetriol, adamantanetriol and the like can be used in small amounts.

[Production method of polyester resin]
A method for producing a polyester resin from the polyvalent carboxylic acid component (A) and the polyol component (B) will be described.
The polyester resin used in the present invention is prepared by, for example, blending a polyvalent carboxylic acid component (A) and a polyol component (B) at a predetermined ratio, and preferably performing an esterification reaction and a polymerization reaction in the presence of a catalyst. Can be obtained.

  In the esterification reaction, a catalyst is preferably used. Examples of the catalyst include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, and germanium-based catalysts such as germanium oxide. Zinc acetate, manganese acetate, dibutyltin oxide, etc. are mentioned. One selected from these may be used alone, or two or more may be used in combination. Of these, tetrabutyl titanate and antimony trioxide are preferred because of their high catalytic activity.

  The compounding amount of the catalyst is preferably 0.0001 to 0.1 times mol, particularly preferably 0.0001 to 0.05 times mol for the polyvalent carboxylic acid component (A). More preferably, it is 0.0001 to 0.01 times mol. If the blending amount of the catalyst is too small, the polymerization reaction tends not to proceed sufficiently, and if it is too large, there is no advantage such as shortening the reaction time, and side reactions tend to occur.

  The temperature during the esterification reaction is preferably 140 to 260 ° C, particularly preferably 160 to 250 ° C, and further preferably 180 to 250 ° C. If the temperature during the esterification reaction is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur. The esterification reaction is preferably carried out under normal pressure.

  After the esterification reaction is performed, a polycondensation reaction is performed. In this polycondensation reaction, the catalyst that can be used in the esterification reaction is further blended in the above blending amount, the reaction temperature is preferably set to 220 to 280 ° C., particularly preferably 230 to 270 ° C., and the reaction system is gradually set up. It is preferable to carry out the reaction at a pressure of 5 hPa or less under a reduced pressure. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur.

The polyester resin thus obtained preferably has a melting point of 60 ° C. or higher, particularly preferably 70 to 180 ° C., and more preferably 80 to 160 ° C. When the melting point is too low, the heat resistance tends to decrease.
In the present invention, the melting point can be measured by, for example, a differential scanning calorimeter DSC2920 manufactured by TA Instruments.

  The number average molecular weight of the polyester resin is preferably 5,000 to 50,000, particularly preferably 6,000 to 40,000, and further preferably 7,000 to 30,000. If the number average molecular weight is too large, the solution stability tends to decrease, and if it is too small, the adhesive force tends to decrease.

  The acid value of the polyester resin is preferably 5 mgKOH / g or less, particularly preferably 4 mgKOH / g or less, and further preferably 3 mgKOH / g or less. If the acid value is too high, the molecular weight tends to decrease due to hydrolysis.

In the present invention, the number average molecular weight can be calculated, for example, from the acid value and hydroxyl value by the terminal group quantification method according to the following formula, and the acid value and hydroxyl value are measured in accordance with JIS K 0070. be able to.
Number average molecular weight = 56.11 × 1000 × 2 / (acid value + hydroxyl value)

The glass transition temperature (Tg) of the polyester resin is preferably 45 ° C. or less, particularly preferably −10 to 45 ° C., more preferably −5 to 40 ° C., and still more preferably 0 to 35 ° C. . If the glass transition temperature (Tg) is too high, the adhesive force tends to decrease, and if it is too low, the tackiness becomes strong. For example, when the substrate such as a film coated with this adhesive is wound up once, it sticks. , Tend to be difficult to unwind.
The glass transition temperature (Tg) can be measured using, for example, a differential scanning calorimeter DSC2920 manufactured by TA Instruments.

The polyester-based adhesive of the present invention is obtained by dissolving the polyester-based resin in an organic solvent.
Examples of the organic solvent include aromatic solvents such as toluene, benzene, xylene, aromatic hydrocarbon compounds, methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2,2-tetra. Chlorine solvents such as chloroethane, chlorobenzene and dichlorobenzene, ester solvents such as ethyl acetate, butyl acetate, isophorone and γ-butyrolactone, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohequinone, diethyl ether, ethyl cellosolve Ether solvents such as butyl cellosolve, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, n-butane, isobutane, n-pe Examples thereof include aliphatic hydrocarbon solvents such as tan, n-hexane, n-heptane, n-octane, and nonane, and alicyclic hydrocarbon solvents such as cyclopentane and cyclohexane, and are selected from the group consisting of these organic solvents. At least one solvent can be used. Preferably, it is at least one solvent selected from the group consisting of aromatic solvents and ketone solvents, for example, a mixed solvent of toluene and methyl ethyl ketone.
The blending ratio of the organic solvent to the whole polyester adhesive of the present invention is usually 20 to 90% by weight, preferably 40 to 90% by weight, particularly preferably 60 to 85% by weight. When the blending ratio is too small, the solution stability tends to decrease, and when the blending ratio is too large, it is difficult to ensure a sufficient adhesive thickness.

  Additives such as antioxidants, ultraviolet absorbers, stabilizers, anti-static agents, inorganic or organic fillers, powders such as metal powders and pigments, particulates, etc. to the polyester adhesive of the present invention An agent etc. can be mix | blended as needed.

  The polyester-based adhesive of the present invention is excellent in adhesiveness not only for resin base materials such as polyethylene terephthalate (PET) but also for non-resin base materials such as metal, wood, paper, leather, etc. In addition to being useful for bonding, it is also useful for bonding a non-resin base material and a resin base material. Therefore, the polyester-based adhesive of the present invention is useful as an adhesive for forming a flat cable for bonding a metal wiring that is a conductor and a resin base material, and other adhesives. The polyester-based adhesive of the present invention is also useful for applications such as paints, coating agents, and ink binders as applications other than adhesives.

<Flat cable forming adhesive / flat cable>
A case where the polyester adhesive of the present invention is used as an adhesive for forming a flat cable will be described together with a flat cable.
The adhesive for forming a flat cable of the present invention is used as an adhesive interposed between a resin base material and a conductor in a flat cable. The flat cable of the present invention has a configuration in which the flat cable forming adhesive of the present invention is interposed between a resin substrate and a conductor.

Examples of the conductor in the flat cable include metal wiring made of tin-plated copper or copper.
As the resin of the resin base material in the flat cable, a resin excellent in mechanical strength, dimensional stability, etc. and having high heat resistance, flexibility, chemical resistance, solvent resistance, flexibility, insulation, etc. is suitable. Among them, polyester resins are preferable. Examples of the polyester resin include PET, polybutylene terephthalate, and polyethylene naphthalate. Further, polyamide resins such as nylon 12, nylon 66, nylon 6, etc., polyphenylene sulfide resin, polyimide resin, liquid crystal polymer, polyether ether ketone resin, and the like can also be used.

  The resin base material may be either unstretched or stretched in a uniaxial direction or a biaxial direction. The thickness of the resin substrate is preferably about 5 to 100 μm, particularly preferably about 9 to 50 μm, and more preferably about 9 to 20 μm, from the viewpoint of workability and cost of the step of laminating an adhesive layer or the like on the surface. preferable. Further, the surface of the resin base material can be optionally subjected to corona treatment, plasma treatment, ozone treatment, other pretreatments, and the like as necessary. In addition, an anchor coat layer may be provided on the resin base material, thereby improving the adhesion between the resin base material and the adhesive, suppressing the delamination, and improving the heat bonding processing speed, Adhesiveness can be improved.

  In the adhesive for forming a flat cable of the present invention, a flame retardant, a polyamide-based wax, silica fine particles, talc, calcium carbonate, an organic pigment, an inorganic pigment such as titanium oxide, carbon, wax, and the like, if necessary. Can be blended.

The method for producing the flat cable of the present invention by using the flat cable forming adhesive of the present invention will be illustratively described below.
First, after dissolving the adhesive of this invention in the organic solvent, it apply | coats on a resin base material, volatilizes a solvent, and the film for flat cables with which the adhesive bond layer was laminated | stacked on the resin base material is prepared. About 15-100 micrometers is preferable and the thickness after drying of an adhesive bond layer is especially preferable about 20-40 micrometers. The method of forming the adhesive layer on the resin substrate is not limited to the method of applying an adhesive solution. For example, the resin base material and the adhesive layer may be integrally formed using a multiaxial melt extruder.
Next, two flat cable films are used so that the surfaces of the respective adhesive layers face each other, and a conductor such as metal is interposed between the layers. Heating and pressing is performed using a heating roll or a heating plate, and the adhesive layer is softened and melted to closely bond the adhesive layer and the conductor. As a result, the conductor is embedded in the adhesive layer, and the adhesive layers are self-adhered to each other to prevent generation of a gap between the conductors, and the two flat cable films are sandwiched between the conductors. Integrated.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded. In the examples, “%” and “parts” mean weight basis.

[Example 1]
In a reaction vessel equipped with a thermometer, a stirrer, a rectifying column, a nitrogen introduction tube and a vacuum apparatus, 305.9 parts (1.84 mol) of terephthalic acid and 131.1 parts of isophthalic acid as polyvalent carboxylic acid component (A) ( 0.79 mol), 49.0 parts (0.79 mol) of ethylene glycol as polyol component (B), 189.6 parts (2.10 mol) of 1,4-butanediol and 124.3 parts of 1,6-hexanediol ( 1.05 mol), 0.3 part of tetrabutyl titanate (0.0009 mol, 0.00034 times mol with respect to the polyvalent carboxylic acid component (A)) as a catalyst was charged, and the temperature was gradually raised to 250 ° C., The esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 260 ° C., 0.3 parts of tetrabutyl titanate was charged as a catalyst, the pressure was reduced to 1.33 hPa, and a polymerization reaction was performed for 3 hours to produce a polyester resin.
Further, the mixture was cooled to 100 ° C., a cooling tube was attached, a mixed solvent of toluene / methyl ethyl ketone [80/20 (weight ratio)] was added so as to be a 20% solution, and the mixture was cooled with stirring, and a polyester adhesive (20% Resin solution) was obtained.

[Example 2]
In the production of the polyester-based resin of Example 1, the monomer composition was 321.8 parts (1.94 mol) terephthalic acid, 107.3 parts (0.65 mol) isophthalic acid, and 48.1 parts (0.77 mol) ethylene glycol. A polyester resin was produced in the same manner as in Example 1 except that 139.7 parts (1.55 mol) of 1,4-butanediol and 183.1 parts (1.55 mol) of 1,6-hexanediol were used. In the same manner, a polyester adhesive (20% resin solution) was obtained.

Example 3
In the production of the polyester resin of Example 1, the monomer composition was 306.9 parts (1.85 mol) terephthalic acid, 109.6 parts (0.66 mol) isophthalic acid, and 19.3 parts (0.13 mol) adipic acid. , Ethylene glycol 49.1 parts (0.79 mol), 1,4-butanediol 190.3 parts (2.11 mol) and 1,6-hexane glycol 124.8 parts (1.06 mol) A polyester resin was produced in the same manner as in Example 1, and a polyester adhesive (20% resin solution) was obtained in the same manner.

[Comparative Example 1]
In the production of the polyester resin of Example 1, the monomer composition was 273.0 parts (1.64 mol) terephthalic acid, 117.0 parts (0.70 mol) isophthalic acid, and 65.6 parts (1.06 mol) ethylene glycol. A polyester-based resin was produced in the same manner as in Example 1, except that 275.0 parts (3.05 mol) of 1,4-butanediol and 69.4 parts (0.59 mol) of 1,6-hexanediol were used. In the same manner, a polyester adhesive (20% resin solution) was obtained.

[Comparative Example 2]
In the production of the polyester-based resin of Example 1, the monomer composition was 265.0 parts (1.60 mol) terephthalic acid, 44.2 parts (0.27 mol) isophthalic acid, 116.6 parts (0.80 mol) adipic acid. Except for changing to 33.0 parts (0.53 mol) of ethylene glycol, 215.6 parts (2.39 mol) of 1,4-butanediol and 125.7 parts (1.06 mol) of 1,6-hexane glycol A polyester resin was produced in the same manner as in Example 1, and a polyester adhesive (20% resin solution) was obtained in the same manner.

[Measurement of polyester resin and evaluation of polyester adhesive]
The following measurements and evaluations were performed on the polyester resins and polyester adhesives obtained in Examples 1 to 3 and Comparative Examples 1 and 2. These results are shown in Table 1.

[Mole ratio of resin composition]
After the obtained polyester resin was dissolved in d-chloroform, H-NMR was measured using “200MHZ-NMR” manufactured by Barrier Co., Ltd., and the molar ratio (mol%) of each monomer component was determined.

[Acid value and hydroxyl value]
The acid value and hydroxyl value of the obtained polyester resin were measured according to JIS K0070.

[Number average molecular weight]
It calculated from the acid value and the hydroxyl value by the terminal group determination method.
Number average molecular weight = 56.11 × 1000 × 2 / (acid value + hydroxyl value)

[Glass transition temperature (Tg), melting point]
It measured with the temperature increase rate of 10 degree-C / min with respect to the obtained polyester-type resin using the differential scanning calorimeter DSC2920 by TA Instruments.

[Tin adhesive strength]
The polyester adhesive is coated on a polyethylene terephthalate (PET) film (thickness 50 μm) so that the thickness after drying is 30 μm, and then a tin-plated copper sheet (thickness 1 mm) and a hot roll machine (roll temperature 150). And laminated at a pressure of 0.1 MPa and a speed of 1.5 m / min. The obtained laminate was allowed to stand for 1 day in an environment of 23 ° C. and 65% RH, and then peeled 180 ° at a peeling rate of 100 mm / min using an autograph (“Autograph AGS-H 500N” manufactured by Shimadzu Corporation). The strength (N / 10 mm) was measured. The evaluation criteria are as follows.
(Evaluation)
○ ・ ・ ・ 10N / 10mm or more △ ・ ・ ・ 5N / 10mm or more, less than 10N / 10mm × ・ ・ ・ less than 5N / 10mm

[PET adhesive strength]
The polyester adhesive is applied to a polyethylene terephthalate (PET) film (thickness 50 μm) so that the thickness after drying is 30 μm, and then a polyethylene terephthalate (PET) film (thickness 50 μm) and a hot roll machine (roll) The laminate was obtained by bonding at a temperature of 150 ° C., a pressure of 0.1 MPa, and a speed of 1.5 m / min. The obtained laminate was allowed to stand for 1 day in an environment of 23 ° C. and 65% RH, and then peeled 180 ° at a peeling rate of 100 mm / min using an autograph (“Autograph AGS-H 500N” manufactured by Shimadzu Corporation). The strength (N / 10 mm) was measured. The evaluation criteria are as follows.
(Evaluation)
○ ・ ・ ・ 10N / 10mm or more △ ・ ・ ・ 5N / 10mm or more, less than 10N / 10mm × ・ ・ ・ less than 5N / 10mm

[Solution Stability] The obtained polyester adhesive (20% resin solution [toluene / methyl ethyl ketone = 4/1 (weight ratio)]) was allowed to stand at 23 ° C. and 65% RH for 1 week to evaluate the solution stability. Was performed visually. The evaluation criteria are as follows.
(Evaluation)
○ ... No gelation in 7 days.
Δ: Gelled in 2 to 6 days.
X: Gelled within 1 day.

From the above results, it can be seen that the polyester adhesives of Examples 1 to 3 have high adhesion to both tin and PET and good solution stability.
On the other hand, it can be seen that the polyester-based adhesive of Comparative Example 1 having a low 1,6-hexanediol content has poor solution stability in addition to low adhesion to tin.
Moreover, although the content of 1,6-hexanediol is large, it can be seen that the polyester-based adhesive of Comparative Example 2 having a large content of adipic acid has extremely low adhesion to tin and PET and is poor in adhesion.

  The polyester-based resin of the present invention is excellent not only in resin base materials such as polyethylene terephthalate (PET) but also in non-resin base materials such as metal, wood, paper, leather, etc. It is useful not only for adhesion but also for adhesion between a non-resin substrate and a resin substrate. Therefore, the polyester-based adhesive of the present invention is useful as an adhesive for forming a flat cable for bonding a metal wiring that is a conductor and a resin base material, and other adhesives. The polyester-based adhesive of the present invention is also useful for applications such as paints, coating agents, and ink binders as applications other than adhesives.

Claims (7)

A polyester adhesive containing a polyester resin composed of a polyvalent carboxylic acid component (A) and a polyol component (B),
As the polyvalent carboxylic acid component (A), it contains at least terephthalic acid and isophthalic acid,
The polyol component (B) contains 1,6-hexanediol, 1,4-butanediol and ethylene glycol,
The content of adipic acid that may be contained as the polyvalent carboxylic acid component (A) is 10 mol% or less,
A polyester-based adhesive, wherein the content of 1,6-hexanediol is 35 mol% or more based on the total of the polyol component (B).   The polyester adhesive according to claim 1, wherein the melting point of the polyester resin is 60 ° C or higher.   The polyester adhesive according to claim 1 or 2, wherein the polyester resin has a number average molecular weight of 5,000 to 50,000.   The polyester adhesive according to any one of claims 1 to 3, wherein the polyester resin has a glass transition temperature of 45 ° C or lower.   The polyester adhesive according to any one of claims 1 to 4, wherein the polyester resin is dissolved in at least one solvent selected from the group consisting of an aromatic solvent and a ketone solvent.   An adhesive for forming a flat cable, wherein the polyester-based adhesive according to any one of claims 1 to 5 is used as an adhesive interposed between a resin substrate and a conductor in a flat cable.   A flat cable, wherein the adhesive for forming a flat cable according to claim 6 is interposed between a resin base material and a conductor.