JPS6367825B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an adhesive resin composition having excellent adhesion to synthetic resin films (or sheets) and metal foils, and particularly to a flame-retardant resin composition for manufacturing flexible printed circuit boards. In recent years, so-called flexible printed circuit boards have been widely used in the electronics field, contributing to the miniaturization and weight reduction of devices. Flexible printed circuit boards are made by laminating copper foil on a synthetic resin film substrate to form a copper-clad laminate sheet, forming a circuit pattern on the copper foil surface by screen printing or photoresist method, and then etching the copper foil by wet etching method. A copper circuit is formed by removing unnecessary parts of the . Synthetic resin films used for this purpose include polyester film, polyimide film, glass cloth reinforced epoxy resin sheet, aramid paper, etc., and their electrical insulation, heat resistance, chemical resistance,
It is important because of its mechanical properties. In addition, the adhesive layer used to bond these synthetic resin films and copper foil must also have excellent electrical insulation, heat resistance, chemical resistance, etc., and there are problems in the adhesion process. It must meet performance requirements such as the pot life of the adhesive liquid, the shelf life after coating, and heat sealability. Furthermore, recently there has been an increasing demand for advanced flame retardancy from the standpoint of safety in electronic and electrical equipment, and the above-mentioned flame-retardancy of flexible printed circuit boards is no exception. The adhesive layer used to bond the foil to the foil also needs to be made flame retardant. Incidentally, adhesives based on epoxy resin, acrylic resin, silicone resin, and polyester resin are known as adhesives for flexible printed circuit boards. Polyester resins are particularly used because they exhibit excellent adhesion to polyester bases. However, alone it is thermoplastic;
Since heat resistance is insufficient, epoxy compounds and isocyanate compounds are used as crosslinking agents. Conventionally used isocyanate compounds include tolylene diisocyanate, trimethylolpropane adducts (Dismodyur L manufactured by Bayer, Coronate L manufactured by Nippon Polyurethane Co., Ltd., etc.), polymethylene polyphenylene isocyanate. (Millionate manufactured by Nippon Polyurethane Co., Ltd.)
MR, Mondueur manufactured by Mobay Chemical Co., Ltd.
(MRS, etc.), phenol-blocked products, ketoxime-blocked products, etc., each of which has its own advantages and disadvantages and is used accordingly. However, when these conventional polyester resin/isocyanate adhesives are used for flexible printed circuit boards, no one has yet been found that satisfies all required performances. For example, if an isocyanate compound blocked with phenol or the like is used to extend the pot life of the adhesive solution, during heat sealing or curing, the phenol or other low molecular weight compound separates, foams, and forms an adhesive. spoil one's sexuality. Tolylene diisocyanate trimethylolpropanated additives and polymethylene polyphenylene isocyanate compounds have high reactivity, and the pot life of adhesives and the shelf life of coated products are short, so their use is extremely limited. Furthermore, when used in flexible printed circuit boards, heat resistance (solder resistance) and solvent resistance are important performance requirements, but there has been no polyester/isocyanate adhesive that satisfies these requirements. Moreover, a flame-retardant polyester/isocyanate adhesive that satisfies the above properties has not yet been found. It is generally known to add organic and/or inorganic flame retardants such as organic halogen compounds, phosphorus compounds, and antimony compounds to flame retardant synthetic resins, adhesives, paints, and the like. However, in order to obtain a flame-retardant adhesive resin composition for manufacturing flexible printed circuits, which is one of the objectives of the present invention, it is necessary to have not only flame retardancy but also adhesive stability, soldering heat resistance, flexibility, and resistance. Must have excellent solvent properties. In particular, the stability of adhesives, that is, the absence of sedimentation of the flame retardant during storage, and the long pot life are extremely important properties. It is thought that this will have a considerable impact. The inventors of the present invention have conducted intensive research to solve the above-mentioned problems. As a result, they have discovered that the flame-retardant adhesive resin has excellent flame retardancy and stability as an adhesive, and is particularly suitable for use in flexible printed circuit boards. We discovered a composition and arrived at the present invention. That is, the present invention provides a saturated polyester resin (a) containing at least 30 mol% of an alkylene terephthalate component, a polyfunctional isophorone isocyanate compound (b), a brominated epoxy resin and its derivatives.
(c) is composed of an antimony compound (d) with an average particle diameter of 0.01 to 5 μm and a solvent (e), and the weight ratio of (a) and (b) is (a)/(b) = 95/5 to The blending ratio of (c) is 5 to 30 parts by weight per 100 parts by weight of (a) + (b) as a halogen content, and the blending ratio of (b) is (a) as an antimony content. ) + (b) 0.5 to 25 parts by weight per 100 parts by weight of a flame-retardant resin composition for adhesives. The saturated polyester resin (a) containing at least 30 mol% of an alkylene terephthalate component used in the present invention is an alkylene terephthalate in a saturated polyester resin (1 mol) consisting of a total of 1.0 mol of acid components and 1.0 mol of glycol components. It is a saturated polyester resin whose component ratio is 30 mol% or more when expressed in mol%. Specifically, the alkylene terephthalate unit of a polyester consisting of 0.6 moles of terephthalic acid units, 0.4 moles of isophthalic acid units, 0.7 moles of ethylene glycol units, and 0.3 moles of neopentyl glycol units is 0.6 x 0.7 + 0.6 x 0.3 = 0.6, which is 60 moles. It means %. Acid components other than terephthalic acid (or its ester-forming derivative) that form the polyester of the present invention, in acid form, include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid, succinic acid, and adipine. acid, azelaic acid,
There are aliphatic dicarboxylic acids such as sebacic acid, dodecanedioic acid, and dimer acid. In the form of glycol, the alkylene glycol (or its ester-forming derivative) forming the polyester resin (a) of the present invention includes ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, etc. , diethylene glycol, triethylene glycol, ethylene glycol ether of 2,2-bis(hydroxyphenyl)propane, and other glycols containing an ether bond are also included as alkylene glycols. The hydroxy compounds (or ester-forming derivatives thereof) other than those mentioned above, which are used in the polyester resin (a) of the present invention, are shown in the form of hydroxy compounds:
Examples include hydroquinone, resorcinol, 2,2-bis(hydroxyphenyl)propane, and the like. The polyester resin (a) used in the present invention is a saturated polyester resin (a) containing an alkylene terephthalate component at least 30 mol% or more, preferably 50 mol% or more. If it is less than 30 mol%, even if an isophorone isocyanate compound is used in combination, the adhesive will have poor heat resistance and solvent resistance, which is not preferable. Particularly preferred alkylene terephthalate units are ethylene terephthalate units. Also, the saturated polyester resin used in the present invention
(a) may contain polyfunctional units such as trimellitic acid units, pyromellitic acid units, trimethylolpropane units, and pentaerythritol units. The intrinsic viscosity of the polyester resin (a) of the present invention is phenol/1,1,2,2-tetrachloroethane=
As a mixed volume of 60/40 (weight ratio), 0.2~ at 30℃
1.5 dl/g, preferably 0.4-0.7 dl/g. One of the preferred embodiments of the present invention is to use a mixture of two or more types of polyester resins. The polyfunctional isophorone isocyanate compound (b) used in the present invention refers to an isophorone diisocyanate compound and a compound having three or more isocyanate groups derived from isophorone diisocyanate. For example, isophorone diisocyanate, trimethylolpropane adduct of isophorone diisocyanate (Takenate D-140N, manufactured by Takeda Pharmaceutical Co., Ltd.), isophorone diisocyanate trimer (IPDI-T-1890, manufactured by VEBA-CHEMIE AG)
and so on. One of the characteristics of the isophorone isocyanate compound (b) is that it can extend the pot life of the adhesive solution and the shelf life of the coated product compared to other isocyanate compounds. Furthermore, the cured product reacted with the polyester of the present invention has high heat resistance (solder resistance) and excellent solvent resistance, which together make it suitable as an adhesive for printed circuit boards. The company is responsible for meeting the required performance. The mixing weight ratio of the polyester resin (a) and isophorone isocyanate compound (b) of the present invention is from 60/40 to
It is 95/5. If this ratio is less than 60/40 (that is, if the amount of isocyanate is increased), the shell life of the coated product will be shortened and the adhesive strength will be reduced, which is not preferable. On the other hand, if it is larger than 95/5, the heat resistance and solvent resistance will not be sufficient, which is not preferable. Examples of the brominated epoxy resin and its derivative (c) used in the present invention include brominated phenolic epoxy resin [Blen S (manufactured by Nikkayaku Co., Ltd.]),
Examples include brominated bisphenol A-type epoxy resin [trade name: Epotote YOB400 (manufactured by Toto Kasei Co., Ltd.)]. Brominated epoxy resin and its derivatives (c) react with polyester end groups, and also react with carboxyl groups and hydroxyl groups contained in the epoxy resin or with epoxy rings, and the generated hydroxyl groups chemically bond with isocyanate groups. It has excellent soldering heat resistance at high temperatures. Because it reacts with isocyanate groups and polyester end groups, high temperatures (over 300℃) are required.
It does not have the disadvantage of being liberated by evaporation or sublimation during soldering and reducing soldering heat resistance. The amount of the brominated epoxy resin and its derivative (c) used in the present invention is the sum of the saturated polyester resin (a) and the polyfunctional isophorone isocyanate compound (b), that is, 100 parts by weight of (a) + (b). As for the halogen content (in terms of halogen atoms),
It is necessary that the amount is 5 to 30 parts by weight. If the amount is less than the lower limit, sufficient flame retardancy cannot be obtained, and if it exceeds the upper limit, various properties such as adhesiveness, solvent resistance, and flexibility will deteriorate, which is not preferable. Examples of the antimony compound (d) used in the present invention include antimony trioxide, antimony pentoxide, and antimony phosphate, and the average particle size thereof is 0.01 to 5 μm from the viewpoint of dispersion stability in the adhesive. . The amount of the antimony compound (d) used in the present invention is the sum of the saturated polyester resin (a) and the polyfunctional isophorone isocyanate compound (b), i.e.
The antimony content (in terms of antimony atoms) is 0.5 to 25 parts by weight per 100 parts by weight of (a)+(b). If the blending amount of the antimony compound (d) is less than the lower limit of the above range, a large amount of the organic halogen compound (c) will be required to impart flame retardancy, resulting in deterioration of the physical properties of the adhesive, which is undesirable. If it exceeds this, the coating suitability of the adhesive will decrease and the flame retardancy will not improve as much as expected. The flame retardant resin composition for adhesives of the present invention is diluted with solvent (e) to form a synthetic resin film (or sheet).
or coated on metal foil. Solvents (e) used in the present invention include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, hydrocarbons such as toluene and xylene, methylene chloride, 1,1, Halogenated hydrocarbons such as 1-trichloroethane, ethers such as dioxane and tetrahydrofuran,
Nitrated hydrocarbons such as nitroethane and nitromethane, and ether esters such as cellosolve acetate are used, but there are no particular limitations. The proportion of the solvent (e) in the flame-retardant adhesive resin composition of the present invention is usually 20 to 95% by weight. Although there are no particular limitations on the method for producing the flame-retardant resin composition for adhesives of the present invention, usually a solution of a saturated polyester resin (a) dissolved in a solvent (e) is added with a polyfunctional isophorone isocyanate (b), an organic halogen compound ( c), blending antimony compound (d), roll mill, ball mill,
Dissolve using a bead shaker, high-speed dissolver, etc.
Manufactured by dispersion. The flame-retardant resin composition for adhesives of the present invention can be applied onto a synthetic resin film (or sheet) or metal foil by a conventional coating method, such as bar coating, roll coating, gravure coating, or spray coating. can.
As an adhesion method, for example, a method of drying the coating film, bonding it to an adherend, and curing it under heat and pressure is usually used. The coating thickness is usually 1 μm to 200 μm, preferably 5 μm to 100 μm. Drying conditions for the coating film are room temperature to 180°C, preferably 50°C to 150°C. After drying, it is preferable to perform a curing reaction by bonding with an adherend after seasoning at room temperature to 50°C and 30% RH to 90% RH, but this is not particularly limited. Curing conditions are 120°C to 180°C for several seconds to 1 hour, preferably 30 seconds to
It takes 30 minutes and you can also do a post-cure. Drying conditions and curing conditions may be appropriately selected depending on the solvent used, the amount of water present, the presence or absence of a curing catalyst such as dibutyltin dilaurate, the type of adherend, etc. The flame-retardant resin composition for adhesives of the present invention is usually applied to a film or sheet made of polyesterimide, epoxy resin, or polyvinyl chloride used for flexible printed circuit boards, or an adhesive used by coating these. Synthetic resin films (or sheets) including agent layers (epoxy resin-based, synthetic rubber-based, silicone-based), copper foil, aluminum foil, steel foil (these may be plated with other metals), or synthetic It not only shows excellent adhesion to metal layers formed directly on resin films (or sheets) by chemical plating, vapor deposition, sputtering, ion plating, etc., but also has flame retardant properties, electrical insulation properties, and solvent resistance. It exhibits excellent performance in terms of flexibility and flexibility. It also has extremely good adhesive stability. Applications of the flame retardant resin composition for adhesion of the present invention are (1) lamination of a synthetic resin film (or sheet) and copper foil or aluminum foil; (In this case, a synthetic resin film (or sheet) is formed on a metal foil coated with an adhesive, or conversely, an adhesive is applied to a synthetic resin film (or sheet) and then a metal foil layer is formed on top of the adhesive. In particular, crosslinked polyester is particularly preferred as the synthetic resin film (or sheet). (2) Bonding a synthetic resin film (or sheet) to the circuit surface as a coverlay for flexible printed circuit boards. (3) Attaching metal foil (or board) or synthetic resin board to the opposite side of the circuit surface of the flexible printed circuit board. (4) Lamination of the synthetic resin film (or sheet) side of the flexible copper-clad laminate sheet with metal foil (or plate) or synthetic resin board. (5) Pretreatment for through-hole plating. In addition to the above-mentioned uses, the flame-retardant resin composition for adhesives of the present invention can be used for electrical and electronic parts that take advantage of the excellent properties described above, namely adhesiveness, heat resistance, solvent resistance, flame retardance, and electrical insulation properties. It can also be widely used for adhesives, coatings, etc. In order to impart other functions to the adhesive resin composition of the present invention, known coloring agents, thixotropic agents, surface smoothing agents, antifoaming agents, and the like can also be blended. EXAMPLES In order to specifically explain the present invention, Examples will be given below, but the present invention is not limited to these Examples in any way. Evaluation methods and test methods in Examples are as follows. 1 Intrinsic viscosity of saturated polyester resin Measured at 30°C in phenol/1,1,2,2-tetrachloroethane 60/40 (weight ratio). 2 Pot Life of Adhesive The change in viscosity over time at 23°C was measured using a VS type rotational viscometer. We also investigated changes in appearance. 3 Measurement of shelf life after coating After coating the adhesive resin composition on one side of a cross-linked polyester film (75μ) to a thickness of 100μ, drying at 100℃ for 1 minute, and drying the coated layer at room temperature of 23℃. Changes in the rate of decrease in isocyanate groups (-NCO) were investigated over time. Isocyanate group (-
The decrease rate change in CH absorbance (D _CH ) at 2920 cm ^-1 and 2260 cm ^-1 is determined by infrared absorption spectrum.
It was determined from the relative ratio of NCO absorbance (D _NCO ). 4 Measurement of adhesive strength A sample was prepared by coating the copper foil surface with 1 mm of resist and etching, leaving 1 mm of copper foil, and heated at 20℃.
Peel at 90℃ at 65%RH and tensile speed of 50mm/min. 5 Soldering heat resistance Tested at 260° x 20 seconds according to JIS C6481. 6 Evaluation of flame retardancy Evaluated according to UL-94 combustion test method and JIS D-1201 oxygen index method. Examples 1 to 3 Saturated polyester/isophorone diisocyanate trimer listed in Table 1 (VEBA IPDI-
T1890) = 30% solution adjusted to 90/10 (solid weight ratio) (however, the solvent is methyl ethyl ketone/toluene/xylene/ethylene glycol acetate = 32/117/2/1 (weight ratio)) 100 weight In the section, brominated bisphenol A type epoxy resin [Product name: Epotote YDB400 (manufactured by Toto Kasei Co., Ltd.) 20
5 parts by weight of antimony trioxide having an average particle size of 0.5 μm were blended and dispersed using a bead shaker to obtain a flame-retardant adhesive resin composition of the present invention. The obtained flame-retardant adhesive resin composition was coated to a thickness of 100 μm on one side of a 75 μm thick crosslinked polyester film using a bar coater. Next, after drying at 100℃ for 5 minutes, and leaving it in a room at 20℃ and 65%RH for 7 days, 35μ electrolytic copper foil (T-
It was placed on top of the treated surface of 5B) and heat pressed at 150°C and 4Kg/cm ² for 1 minute to bond them together. The performance of the obtained laminated sheet was as shown in Table 2. For comparison, Comparative Example 2 shows the results of a similar experiment using 25 parts by weight of Pyrocheck 77B instead of Epotot YDB400.

【table】

[Table] Examples 3 to 4 Saturated polyester resin (B)/(C) = listed in Table 1
30% solution adjusted to have 80/20 (weight ratio) 90 parts by weight and isophorone diisocyanate trimer (mentioned above) 10 parts by weight (however, as a solvent, methyl ethyl ketone/toluene/xylene/ethylene glycol acetate = 32/117/2 /1 (weight ratio)) to 100 parts by weight, brominated phenol novolac type epoxy resin [Blen S (manufactured by Nippon Kayaku Co., Ltd.)] and average particle size
Antimony trioxide of 0.5 μm was blended at various blending ratios and evaluated in the same manner as in Examples 1 and 2. The results are shown in Table 4. Example 5 Evaluation was carried out in the same manner as in Examples 3 and 4, except that antimony trioxide having an average particle diameter of 3 μm was used instead of the antimony trioxide used above. The results are shown in Table 3. Comparative Example 3 Evaluation was carried out in the same manner as in Examples 3 and 4, except that antimony trioxide having an average particle size of 6 μm was used instead of the antimony trioxide used above. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1 Alkylene terephthalate component at least
Saturated polyester resin containing 30 mol% (a), polyfunctional isophorone isocyanate compound (b), brominated epoxy resin and its derivatives (c), average particle size
It is composed of an antimony compound (d) of 0.01 to 5 μm and a solvent (e), and the blending ratio of (a) and (b) is (a)/(b) =
It is in the range of 95/5 to 60/40, and the blending ratio of (c) is 5 to 100 parts by weight of (a) + (b) as halogen content.
30 parts by weight, and the blending ratio of (b) is 0.5 to 25 parts by weight based on 100 parts by weight of (a)+(b) as antimony content.