JP5050429B2 - Polyester resin composition and adhesive containing the same - Google Patents

Description

  The present invention relates to a polyester resin composition particularly suitable for an adhesive for flexible flat cables used for wiring of electric and electronic devices. More specifically, it is suitable as an adhesive for bonding an insulating film of a flexible flat cable. The adhesive of the present invention exhibits excellent blocking resistance and performance excellent in adhesion to polyester films and tin-plated copper.

  In recent years, with the miniaturization of home appliances and automobile parts, multi-core flat flexible flat cables (hereinafter sometimes abbreviated as FFC) have been frequently used for wiring between circuit boards. The FFC has a structure in which a tin-plated copper foil is bonded to an insulating film via an adhesive, that is, an insulating film / adhesive / metal conductor / adhesive / insulating film structure. As the insulating substrate, a biaxially stretched polyethylene terephthalate (PET) film layer having excellent mechanical properties and electrical properties is often used.

  Recently, flat cables are often used for wiring of movable parts, and accordingly, demands for bending resistance and heat resistance are increasing. In order to improve the bending resistance of flat cables, it is generally necessary to improve the adhesion between the conductor and the insulating substrate. Therefore, a resin with excellent adhesion to the conductor is selected for the adhesive layer, and thermoplastic saturated copolymer A united polyester is mainly used (for example, see Patent Document 1). However, conventionally known polyester-based adhesives are inferior in adhesiveness at the time of bonding at low temperature, and an adhesive excellent in bending resistance, heat resistance and blocking resistance has not yet been proposed.

Japanese Patent Laid-Open No. 5-17727

  An object of the present invention is to provide an adhesive for FFC that can achieve both good adhesion and blocking property to tin-plated copper and excellent heat resistance with respect to an adhesive used for FFC of wiring parts in automobile parts, electrical appliances and the like. It is to provide.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to achieve the above-mentioned problems. That is, this invention is the following resin compositions and adhesives, and FFC using the same.
Amorphous polyester resin (A) having a number average molecular weight of 5000 to 40000, a glass transition temperature of 50 ° C. or higher, and a carboxyl end group of 50 to 300 eq / 10 ⁶ g, a number average molecular weight of 5000 to 40000, a glass transition temperature A polyester resin composition comprising an amorphous polyester resin (B) having a temperature of less than 20 ° C. and a blending ratio of (A) / (B) = 10/90 to 50/50 (weight ratio), It is the flexible flat cable using the adhesive agent containing the adhesive agent.

  The resin composition obtained in the present invention is useful as an adhesive having excellent adhesion to tin-plated copper and anti-blocking property, and particularly exhibits an excellent effect as an adhesive for FFC.

The carboxyl end group of the polyester resin (A) used in the present invention is 50 to 300 eq / 10 ⁶ g. More preferably, it is 50-200eq / 10 < ⁶ > g, More preferably, it is 80-150eq / 10 < ⁶ > g. When the carboxyl end group exceeds this range, the properties such as adhesion to metal, heat resistance, and hydrolysis resistance may be inferior.

  The number average molecular weight of the polyester resin (A) and the polyester resin (B) used in the present invention is preferably 5000 to 40000. More preferably, it is 10000-35000. If the number average molecular weight is lower than 5,000, the mechanical properties as an adhesive may be insufficient and sufficient adhesiveness and heat resistance may not be obtained. If it exceeds 40,000, the melt viscosity at the time of heating and melting increases, The laminating temperature tends to increase.

  The glass transition temperature of the polyester resin (A) used in the present invention is 50 ° C. or higher. Preferably it is 55 degreeC or more, More preferably, it is 60 degreeC or more. When the glass transition temperature is 50 ° C. or lower, blocking may occur, and it becomes difficult to handle a substrate such as a film after applying an adhesive. Although an upper limit is not specifically limited, It is preferable that it is less than 120 degreeC from an adhesive viewpoint. On the other hand, the glass transition temperature of the polyester resin (B) is less than 20 ° C. Preferably it is less than 15 degreeC, More preferably, it is less than 10 degreeC. When the glass transition temperature is 20 ° C. or higher, the adhesion to metal tends to be inferior. Although a minimum is not specifically limited, When blocking property, adhesiveness, and the handleability of resin are considered, it is preferable that it is -30 degreeC or more.

  The dispersion ratio (hereinafter Mw / Mn) of the weight average molecular weight (Mw) / number average molecular weight (Mn) of the polyester resin (A) used in the present invention is preferably 2.5 to 4.0. More preferably, it is 2.7 to 3.5. When Mw / Mn is less than 2.5, the heat resistance as an adhesive tends to be inferior. On the other hand, if it exceeds 4.0, the adhesiveness as an adhesive may be inferior.

  As the dibasic acid component of the polyester resin (A) and the polyester resin (B) used in the present invention, the following polyvalent carboxylic acids, or alkyl esters or acid anhydrides thereof can be used. Examples of the polyvalent carboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, and 2,2′-diphenyl. Aromatic dibasic acids such as dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, adipic acid, azelaic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid Acids, 4-methyl-1,2-cyclohexanedicarboxylic acid, dimer acid and other aliphatic and alicyclic dicarboxylic acids, trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid, biphenyltetracarboxylic acid, ethylene glycol bis (amnes Hydrotrimellitate), glycerol tri And aromatic polycarboxylic acids (anhydrotrimellitate), and the like. In view of heat resistance and flexibility, it is more preferable that terephthalic acid and / or isophthalic acid is an essential component of 50 mol% or more of the total acid components.

  Further, the glycol component is not particularly limited, but ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2- Butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, Dipropylene glycol, 2,2,4-trimethyl-1,5-pentanediol, ethylene oxide adduct and propylene oxide adduct of bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, 1,9 -Nonanediol, 2-methyloctanediol, 1,1 - decanediol, polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polycarbonate glycol. Among these glycol components, ethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,9-nonanediol, polytetra Methylene glycol, polypropylene glycol, polyethylene glycol, and polycarbonate glycol are preferred from the viewpoint of adhesion to metal and dissolution stability.

  A method for introducing a carboxyl group into a polyester resin is that after polymerizing the polyester resin, trimellitic anhydride, phthalic anhydride, pyromellitic anhydride, succinic anhydride, maleic anhydride, anhydrous 1, 8-Naphthalic acid, 1,2-cyclohexanedicarboxylic anhydride, cyclohexane-1,2,3,4-tetracarboxylic acid-3,4-anhydride, ethylene glycol bisanhydro trimellitate, 5- (2,5 -Dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, naphthalene-1,8: 4,5-tetracarboxylic dianhydride, etc. Add these selected anhydrides, add them, add these acid anhydrides to the oligomer before polycondensation of the polyester, By high molecular weight by polycondensation reaction pressure, but are not particularly limited and a method of introducing a carboxyl group into the polyester resin. The former method is preferred for efficiently introducing a carboxyl group. Preferred acid anhydrides include trimellitic anhydride, ethylene glycol bis (anhydro trimellitate), and glycerol tris anhydro trimellitate.

  As a method for adjusting the Mw / Mn (dispersion ratio) of the amorphous polyester resin (A) used in the present invention to 2.5 to 4, a method of introducing a branched structure in the polyester molecule is preferable. Copolymerization components for introducing branching include polyfunctional carboxylic acids such as trimellitic anhydride, ethylene glycol bis (anhydrotrimellitate), glycerol trisanhydrotrimellitate, and other polyfunctional carboxylic acids such as trimethylolpropane and pentaerythritol. There is a method using a functional glycol. The copolymerization amount of these components is preferably in the range of 0.01 to 10 mol%.

  In the present invention, the blending ratio of the amorphous polyester resin (A) and the amorphous polyester resin (B) is (A) / (B) = 10/90 to 50/50 in weight ratio. More preferably, it is 20 / 80-30 / 70. When the polyester resin (A) component is less than 10% by weight, the blocking property may be inferior. On the other hand, when the amount of the polyester resin (B) is less than 50% by weight, the adhesion to metal may be lowered.

  In addition, a flame retardant can be used together with the polyester resin composition of the present invention as necessary. Examples of the flame retardant include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, triethyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, cresyl bis (2,6-xylenyl) phosphate Fate, 2-ethylhexyl phosphate, dimethyl methyl phosphate, resorcinol bis (diphenyl) phosphate, bisphenol A bis (diphenyl) phosphate, bisphenol A bis (dicresyl) phosphate, diethyl-N, N-bis (2-hydroxy) Ethyl) aminomethyl phosphate, phosphoric acid amide, organic phosphine oxide, phosphorous flame retardants such as red phosphorus, ammonium polyphosphate, phosphazene, cyclophosphazene Nitrogen such as triazine, melamine cyanurate, succinoguanamine, ethylene dimelamine, triguanamine, triazinyl cyanurate, melem, melam, tris (β-cyanoethyl) isocyanurate, acetoguanamine, guanylmelamine sulfate, melem sulfate, melam sulfate Flame retardant, potassium diphenylsulfone-3-sulfonate, aromatic sulfonimide metal salt, polystyrene sulfonate alkali metal salt, etc., aluminum hydroxide, magnesium hydroxide, dolomite, hydrotalcite, hydroxylation Hydrated metal flame retardants such as barium, basic magnesium carbonate, zirconium hydroxide, tin oxide, silica, aluminum oxide, iron oxide, titanium oxide, manganese oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide Den, cobalt oxide, bismuth oxide, chromium oxide, tin oxide, antimony oxide, nickel oxide, copper oxide, tungsten oxide, zinc borate, zinc metaborate, barium metaborate, zinc carbonate, magnesium carbonate, calcium carbonate, barium stannic acid Inorganic flame retardants such as zinc and silicon flame retardants such as silicone powder. Higher flame retardant effect can be obtained from the combined effect of the flame retardant mechanism of the high flame retardancy of the phosphorus compound-containing resin itself and the flame retardant.

  In this polyester resin composition, an epoxy resin, an acid anhydride, a curing agent such as an isocyanate compound, and a curing catalyst such as tin or amine can be used as necessary. In particular, an epoxy resin is very preferable in terms of developing heat resistance.

  Moreover, various additives can be mixed with the polyester resin composition of this invention, and it can use for an adhesive agent and a coating agent. Examples of the additives include crystal nucleating agents such as talc, mica, polyethylene, and various metal salts, coloring pigments, inorganic and fixed fillers, and tackiness improvers in addition to the flame retardants described above.

  For example, when the composition of the present invention is used as an adhesive, an adhesive film can be obtained by dissolving in an organic solvent, coating on a plastic film, and drying. As a dry film thickness, 200 micrometers-3 micrometers are preferable. More preferably, it is 100 micrometers or less, More preferably, it is 70 micrometers or less, and 10 micrometers or more are more preferable.

  As the plastic film, an arbitrary plastic film such as a polyester film (hereinafter abbreviated as PET film), a polyamide film, a polycarbonate film, a polypropylene film, a polystyrene film, a polyimide film, a polyamide film, a polyoxabenzazole film is used. A film is preferable in terms of economy and versatility. The plastic film can be provided with a corona treatment or an easy adhesion layer as necessary.

  In order to describe the present invention in more detail, examples are given below, but the present invention is not limited to the examples. In addition, the measured value described in the Example is measured by the following method.

Resin composition: The resin was dissolved in deuterated chloroform, and ¹ H-NMR analysis was performed using a nuclear magnetic resonance analyzer (NMR) Gemini-200 manufactured by Varian Inc., and the integral ratio was determined.

Glass transition temperature: Using a differential scanning calorimeter, 10 mg of a measurement sample was put in an aluminum pan, sealed with a lid, and 20 ° C. using a differential scanning calorimeter (DSC) DSC-220 manufactured by Seiko Instruments Inc. It was determined by measuring at a heating rate of / min.

Number average molecular weight: Calculated from the results of GPC measurement at a column temperature of 30 ° C. and a flow rate of 1 ml / min using Waters Gel Filtration Permeation Chromatography (GPC) 150c with tetrahydrofuran as an eluent. Measurements were obtained. However, Showa Denko Co., Ltd. shodex KF-802, 804, 806 was used for the column.

Acid value (carboxyl end group amount): 0.2 g of polyester was dissolved in 20 ml of chloroform, and titrated with 0.1 N potassium hydroxide ethanol solution to obtain the equivalent (eq / 10 ⁶ g) per 10 ⁶ g of resin. It was.

<Synthesis example 1 of polyester resin (A)>
In a reaction vessel equipped with a stirrer, thermometer, and cooler for outflow, 83 parts of terephthalic acid, 81 parts of isophthalic acid, 2 parts of trimellitic acid, 77 parts of ethylene glycol, 79 parts of neopentyl glycol are charged under pressure. The temperature gradually increased to 230 ° C. over time, and the esterification reaction was carried out while removing distilled water out of the system. Subsequently, the polymerization catalyst was added, and the mixture was stirred at normal pressure for 10 minutes, and then the initial polymerization under reduced pressure was performed to 10 mmHg over 1 hour, the temperature was increased to 250 ° C., and the latter polymerization was further performed at 1 mmHg or less for 30 minutes. Then, after cooling to 200 degreeC in nitrogen atmosphere, 2 parts of trimellitic acid was prepared, and it stirred for 30 minutes, and obtained polyester resin (A) synthesis example 1. The characteristic values of the polyester resin thus obtained are shown in Table 1.

<Synthesis Examples 2 and 3 of polyester resin (A)>
In the same manner as in Synthesis Example 1, Synthesis Examples 2 and 3 of the polyester resin (A) were prepared. The characteristic values of the polyester resin thus obtained are shown in Table 1.

<Synthesis example 4 of polyester resin (A)>
In a reaction vessel equipped with a stirrer, a thermometer, and an outflow cooler, 83 parts of terephthalic acid, 81 parts of isophthalic acid, 77 parts of ethylene glycol and 79 parts of neopentyl glycol were charged and gradually increased to 230 ° C. over 4 hours. The esterification reaction was carried out while removing the water that rose and distilled out of the system. Subsequently, a polymerization catalyst was added and stirred for 10 minutes at normal pressure. Then, initial polymerization was performed at a reduced pressure to 10 mmHg over 1 hour, the temperature was increased to 250 ° C., and the latter polymerization was further performed at 1 mmHg or less for 30 minutes to obtain a polyester resin ( A) Synthesis example 4 was obtained. The characteristic values of the polyester resin thus obtained are shown in Table 1.

<Synthesis Examples 5 to 8 of polyester resin (B)>
Polyester (B) synthesis examples 5 to 8 were prepared in the same manner as in polyester resin (A) synthesis example 4. The characteristic values of the polyester resin thus obtained are shown in Table 1.

<Example 1>
Tin-plated copper adhesiveness: The polyester resin for adhesive obtained in Synthesis Examples 1 to 8 was dissolved in methyl ethyl ketone / toluene = 1/4 (weight ratio) so that the solid content concentration was 30%. 100 parts of this dissolved polyester resin for adhesive, 50 parts of decabromodiphenyl ether, 36 parts of antimony trioxide, 14 parts of titanium dioxide, 4 parts of silicon dioxide, 100 parts of glass beads, 250 ml mayonnaise bottle And dispersed with a shaker for 6 hours. The obtained dispersion solution was applied onto a 25 μm biaxially stretched PET film so that the thickness after drying was 25 μm, and dried at 120 ° C. for 10 minutes to prepare. Using this, the adhesive layer and tin-plated copper were bonded using a roll laminator manufactured by Tester Sangyo Co., Ltd. The lamination was performed at a temperature of 80 to 120 ° C., a pressure of 0.3 MPa, and a speed of 1 m / min. The adhesive strength was determined by performing a tensile test in an atmosphere of 25 ° C. using RTM100 manufactured by Toyo Baldwin Co., Ltd., and measuring 90 ° peel adhesive strength at a tensile speed of 50 mm / min.

Blocking resistance: Five of the obtained adhesive films were stacked in the same direction so that the adhesive layer and the PET film overlapped alternately. Next, a load of 20 g / cm ² was applied on the adhesive film thus piled up and stored in an atmosphere at 70 ° C. for 72 hours. Thereafter, the adhesive sheet was taken out, the adhesive strength between the stacked sheets was measured, and the following determination was performed.
(Judgment) ○: 0 to 1 N / cm Δ: 1 to 2 N / cm
X: 2 N / cm or more

Heat resistance: FFC (PET film / adhesive layer / tin-plated copper wire / adhesive layer / PET film) using two adhesive films obtained above, sandwiching a tin-plated copper wire with an adhesive layer and bonding with a roll laminator )created. Lamination was performed at a temperature of 160 ° C., a pressure of 0.3 MPa, and a speed of 1 m / min. This FFC was bent at 90 ° and allowed to stand under conditions of 85 ° C. × 90 RH% × 168 hr, and the appearance of the FFC in the bent portion was confirmed.
(Judgment) (circle): Peeling did not arise between an adhesive bond layer and tin plating Cu, or an adhesive bond layer and PET.
X: Peeling occurred between the adhesive layer and tin-plated Cu or between the adhesive layer and PET.

<Examples 2-8, Comparative Examples 1-8>
The evaluation results of Examples 2 to 8 performed in the same manner are shown in Table 2, and the evaluation results of Comparative Examples 1 to 8 are shown in Table 3.

  The adhesive composition of the present invention is superior in metal adhesion and blocking resistance as compared with the prior art.

  On the other hand, as shown in Table 3, in Comparative Examples 1 and 4, since the polyester resin (A) having a low acid value is used, the adhesion to metal is inferior. Moreover, since the polyester resin (A) does not have a branch in a molecule | numerator, heat resistance is also inferior. In Comparative Examples 2 and 3, since the polyester (B) having a high glass transition temperature is used, the adhesion to metal is inferior. In Comparative Examples 5 and 6, since the compounding amount of polyester (B) having a low glass transition temperature is large, the adhesion to metal is excellent, but the blocking resistance is poor. In Comparative Example 7, since the polyester (B) having a high glass transition temperature is used, the adhesion to metal is inferior, and since the blending amount of the polyester resin (B) is large, the blocking resistance is inferior. In Comparative Example 8, since the blending amount of the polyester resin (B) having a low glass transition temperature is small, the adhesion to metal is poor. As can be seen from Table 2, it can be seen that the polyester adhesive of the present invention has excellent performance in adhesion, blocking resistance and heat resistance. On the other hand, as shown in Table 3, Comparative Examples 1 to 8 are inferior in adhesion to tin-plated copper, blocking resistance, and heat resistance.

  The adhesive obtained in the present invention is an adhesive excellent in adhesion to tin-plated copper and blocking resistance, and is useful as an adhesive for FFC.

Claims (7)

Amorphous polyester resin (A) having a number average molecular weight of 5000 to 40000, a glass transition temperature of 50 ° C. or higher, and a carboxyl end group of 50 to 300 equivalents / 10 ⁶ g, a number average molecular weight of 5000 to 40000, and a glass transition A polyester resin composition comprising an amorphous polyester resin (B) having a temperature of less than 20 ° C. and a blending ratio of (A) / (B) = 10/90 to 50/50 (weight ratio).   2. The polyester resin composition according to claim 1, wherein the amorphous polyester resin (A) is a resin obtained by polymerizing the polyester resin and then adding an acid anhydride to the terminal group to modify the carboxyl group. . The polyester resin composition according to claim 1 or 2, wherein the amorphous polyester resin (A) satisfies the following formula (1).
2.5 ≦ weight average molecular weight / number average molecular weight ≦ 4.0 (1)   The adhesive agent containing the polyester resin composition in any one of Claims 1-3.   The adhesive according to claim 4, wherein the adhesive is used for bonding a metal foil and a plastic film.   The adhesive according to claim 4, wherein the adhesive is used for a flexible flat cable.   A flexible flat cable using the adhesive according to claim 6.