JPS6238396B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aromatic polyamide adhesive, and more particularly to an aromatic polyamide adhesive suitable for bonding heat-resistant materials, particularly aromatic polyamide materials. In recent years, as electrical equipment has become smaller and lighter, and its properties have improved, the demand for heat-resistant insulating materials has increased.
Currently, various heat-resistant materials are in practical use. In addition, various composite materials have been put into practical use in consideration of the characteristics and economic efficiency of each material, and the development of heat-resistant adhesives that match the heat resistance of the materials is expected. Polyimide-based polymers and polyamide-imide-based polymers have hitherto been known as heat-resistant adhesives or adhesive varnishes of the H class, but the disadvantage of these is that they are very expensive. In contrast, aromatic polyamides are relatively inexpensive polymers, and the use of aromatic polyamides as adhesives has been known for some time. For example, Special Publication No. 35-14399 or Special Publication No. 37-10098
The publication states that a solution of aromatic polyamide can be used as a varnish and an adhesive. However, aromatic polyamides are usually produced by low-temperature solution polymerization of aromatic diamines and aromatic dicarboxylic acid chlorides in amide solvents, but at that time, hydrochloric acid by-produces calcium hydroxide, calcium oxide, and lithium hydroxide. is neutralized with a base such as lithium carbonate to produce salts such as calcium chloride and lithium chloride, so the resulting aromatic polyamide solution contains these salts. These salts also have the effect of aiding the solubility of the aromatic polyamide in solvents, so when the isolated polymer is redissolved, it is common to dissolve the isolated polymer with these salts present. Therefore, if a solution containing such salts is used as an adhesive as is, salts will remain in the adhesive after adhesion and drying, and these salts will form a complex with the amide solvent. It becomes difficult to completely remove the amide solvent. For this reason, there are problems in that the mechanical properties and electrical properties of the adhesive are significantly reduced, and that the adhesive is thermally deteriorated during use. In addition, paper, nonwoven fabrics made of aromatic polyamide,
When a solution consisting of aromatic polyamide and its solvent is used as an adhesive to bond films or textiles, etc., the adhesive solvent may dissolve or swell the adhered object, causing poor shape of the bonded part. Moreover, there is a problem that the mechanical properties and electrical properties of the adherend are often deteriorated. It is also known to use an aromatic polyamide solvent alone when manufacturing aromatic polyamide paper laminates (Japanese Patent Laid-Open Publication No. 134081/1981, etc.).
However, in this case, since the solvent is used alone, the viscosity is lower than when using an aromatic polyamide solution, so the solvent penetrates into the adherend, and as a result, the solvent dissolves the polymer molecules or causes them to swell. Therefore, there are problems in that the shape of the bonded part is defective and that various physical properties are significantly deteriorated. The present inventors have solved the above-mentioned problems that occur when bonding heat-resistant materials, especially aromatic polyamide materials. As a result of intensive research with the aim of obtaining an adhesive that does not change the form or heat resistance stability of the product, we have found that a solution consisting of an aromatic polyamide and a polar organic solvent, which is a solvent for the aromatic polyamide, is compatible with this polar organic solvent. and a specific amount of a solvent that is a non-solvent for aromatic polyamides, and the content of alkali metal halides or alkaline earth metal halides in the solution is 0 or below a specific amount. The inventors have discovered that this solution is an excellent adhesive that meets these objectives, and have arrived at the present invention. That is, the present invention is composed of the following components (a), (b), and (c), or is composed of the following components (a), (b), (c), and (d); ), (c) and (d) relative to the total amount of components (
The content of component (a) is 0.5 to 40% by weight, and the content of component (d) is 0.5 to 40% by weight.
0.2% by weight or less, and the content ratio of component (B) to component (C) is 97:3 to 30:70 by weight. (a) An aromatic polyamide in which 90 mol% or more of the repeating units are represented by the following general formula. -NH-Ar ₁ -NHCO-Ar ₂ -CO- and/or -NH-Ar ₃ -CO- (However, Ar ₁ , Ar ₂ and Ar ₃ in the formula represent the same or different bifunctional aromatic rings. (2) At least one polar organic solvent selected from the group consisting of NN-dialkylformamide, NN-dialkylacetamide, N-alkyl-pyrrolidone, tetraalkylurea, hesaalkylphosphoramide, and dialkyl sulfoxide. (c) A solvent that is compatible with the polar organic solvent in (b) and is a non-solvent for the aromatic polyamide in (a) (hereinafter referred to as a non-solvent). (d) Alkali metal halides or alkaline earth metal halides. The aromatic polyamide used in the present invention is
The difunctional aromatic ring in the formula is, for example, 1,3- or 1,4-phenylene, 3,3'- or 4,4'-biphenylene,
1,4- or 1,5- or 1,6-naphthylene,
4,4'-oxadiphenyl, 4,4'-carbonyl, 3,3' or 4,4'-sulfonodiphenyl,
Examples include 4,4'-methylene diphenyl. Among these, 1,3- or 1,4-phenylene is particularly preferred. The aromatic polyamide used in the present invention can be prepared, for example, by a low-temperature solution polymerization method or an interfacial polymerization method. In this case, after the polymer is isolated, it is thoroughly washed to remove residual solvents, salts, etc. as much as possible, and then dried and used to prepare an adhesive. The aromatic polyamide used in the present invention has an intrinsic viscosity ηinh (in 96% sulfuric acid, polymer concentration
The relative viscosity (obtained from the relative viscosity measured at 0.5 g/100 ml at 25°C) is preferably in the range of 0.8 to 7.0, particularly 1.0 to 5.5. In the present invention, N,N-
Dialkylformamide, N,N-dialkylacetamide, N-alkylpyrrolidone, tetraalkylurea, hexaalkylphosphoramide or dialkyl sulfoxide is used; in this case, the alkyl group is a methyl group, ethyl group or propyl group, especially a methyl group. is suitable.
In the present invention, these polar organic solvents may be used alone or in combination of two or more. Among these, particularly desirable polar organic solvents are N,N-dimethylacetamide and N-methyl-2-pyrrolidone. Examples of the non-solvent used in the present invention include hydrocarbons such as benzene, toluene, xylene, crude naphtha, petroleum benzene, and cyclohexane, halogenated hydrocarbons such as chloroform, methylene chloride, and carbon tetrachloride, ethyl alcohol, butanol, and dioxane. alcohols, aromatic compounds such as pyridine, chlorobenzene, nitrobenzene, aniline, and water, and these may be used alone or in combination of two or more. Among these, xylene and toluene are particularly preferred in terms of stability when used as an adhesive, boiling point close to that of the polar solvent to be mixed, and no trouble during drying. In the adhesive of the present invention, the content of aromatic polyamide is 0.0 based on the total amount of components (a), (b), (c), and (d).
Five
~40% by weight, especially 1~30% by weight, even 2~
Desirably, it is 25% by weight. When the content of aromatic polyamide is less than 0.5% by weight, the viscosity of the adhesive becomes low, so the adhesive penetrates into the object to be adhered, and if the object is thin, the adhesive may reach the opposite side of the adhesive surface. As a result of the leaching, the shape after drying is markedly poor, and in the case of adherends with rough textures such as non-woven fabrics, the adhesive force is also low. On the other hand, if the content of aromatic polyamide exceeds 40% by weight, the viscosity of the adhesive becomes extremely high, making it impossible to apply it as is. Furthermore, the stability of the adhesive is extremely poor, and gelation, phase separation, etc. are likely to occur. In the present invention, the content ratio ((b)/(c)) of (b) polar organic solvent and (c) non-solvent is in the range of 97/3 to 40/60 in terms of weight ratio, particularly 95/5 to 50/50, preferably in the range of 93/7 to 60/40. If the content of the non-solvent is less than the above range, the degree of decrease in solubility of the solvent due to the addition of the non-solvent will be extremely small, and the effects of the present invention will not be achieved. On the other hand, if the content of the non-solvent exceeds the above range, the stability of the adhesive will deteriorate and gelation and phase separation will occur easily. The adhesive of the present invention does not contain an alkali metal halide or an alkaline earth metal halide, or contains a specified amount or less. The amount of alkali metal halide or alkaline earth metal halide contained in the adhesive of the present invention is preferably as small as possible, relative to the total amount of components (a), (b), (c) and (d). , 0.2% by weight or less, preferably 0.1% by weight or less, more preferably 0.05% by weight or less. The content of these salts is 0.2
If it exceeds % by weight, the alkali metal or alkaline earth metal forms a complex with the polar organic solvent and suppresses the evaporation of the polar organic solvent, so drying during adhesion may not be sufficient and the adhesion may be performed with a small amount of solvent remaining. Complete. Therefore, the mechanical and electrical properties of the adhesive are poor. In order to prepare the adhesive of the present invention, the aromatic polyamide is dissolved in a polar organic solvent using a conventional method, and then a predetermined amount of non-solvent is gradually added while stirring to prevent polymer precipitation. Preferably adopted. In this case, a method in which a non-solvent is added immediately before use as an adhesive is a particularly preferred method from the viewpoint of stability of the adhesive. Alternatively, it can also be prepared by adding aromatic polyamide to a mixed solvent of a polar organic solvent and a non-solvent mixed in a predetermined ratio and dissolving the mixture while stirring.
In this case, the amount of alkali metal halide or alkaline earth metal halide in the adhesive is zero or
The residual amount in the aromatic polyamide is adjusted in advance so that it is 0.2% by weight or less. In addition, if these salts are necessary to assist in dissolving the aromatic polyamide, they can be added at the time of dissolution, provided that the content in the adhesive does not exceed 0.2% by weight. Further, when dissolving the aromatic polyamide, if necessary, the aromatic polyamide may be immersed in a polar solvent or a mixed solvent of a polar solvent and a non-solvent to swell it at a low temperature, and then heated to an appropriate temperature and stirred and dissolved. Another method for preparing the adhesive of the present invention is to polymerize an aromatic polyamide using a conventional low-temperature solution polymerization method, and then use a neutralizing agent that produces a salt that is not soluble in the polymerization solvent during neutralization. The polymerization solution can be neutralized by adding a non-solvent to the neutralized solution, and if necessary, water present in the polymerization solution can be azeotropically removed with the non-solvent, and then salts can be filtered off. , is preferably employed in the preparation of aromatic polyamides containing no alkali metal halides or alkaline earth metal halides. The adhesive of the present invention can be prepared by the various methods described above, but is not limited thereto. The adhesive of the present invention is useful as a heat-resistant classification H class adhesive, and is used, for example, to bond heat-resistant insulating paper, pressboard, nonwoven fabric, film, textile, plastic, and the like. The adhesive of the present invention is particularly effective for adhesion between aromatic polyamide materials or between aromatic polyamide materials and other organic or inorganic materials, but can also be suitably applied to adhesion between materials other than aromatic polyamide. can. In addition, the adhesive of the present invention is usually used alone, but for example, glass fiber, glass powder, powdered silica, asbestos fiber, etc.
It can also be used in combination with inorganic materials such as mica, synthetic fibers such as aromatic polyamide fibers, polyester fibers, and phenolic fibers, natural fibers such as cotton, and other organic materials. The adhesive of the present invention is also useful as an insulating varnish or an insulating paint, and can be widely applied to coil impregnation, electric wires, and other uses. Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that parts in the examples indicate parts by weight. Example 1 75.6 parts of metaphenylenediamine and 32.4 parts of paraphenylenediamine were dissolved in 1000 parts of N,N-dimethylacetamide, and after cooling to 0°C, 203 parts of isophthalic acid chloride powder was gradually added with vigorous stirring. The reaction was allowed to take place for 1 hour. After the reaction was completed, the mixture was neutralized with calcium hydroxide to obtain an aromatic polyamide copolymer solution containing 70 mol% of metaphenylene isophthalamide component and 30 mol% of paraphenylene terephthalamide component. ηinh of the obtained copolymer is
It was 1.56. This copolymer solution was poured into water to isolate the copolymer, which was thoroughly washed with water and dried in a dryer at 105°C. The amount of calcium chloride contained in the copolymer after drying was 0.1% by weight. This copolymer was dissolved in N,N-dimethylacetamide to obtain a solution having a copolymer concentration of 26% by weight. Xylene was added to the resulting solution while stirring to obtain an adhesive containing 19.98% by weight of copolymer, 56% by weight of N,N-dimethylacetamide, 24% by weight of xylene, and 0.02% by weight of calcium chloride. Using this adhesive, two sheets of aromatic polyamide paper having a basis weight of 45 g/m ² and a thickness of 55 mm were adhered, and the condition of the bonded portion was observed. Furthermore, the adhesive strength was measured using an aromatic polyamide board according to the board method adhesive strength measuring method described in JISC-2103. The results are shown in Table 1. Comparative Example 1 Example 1 with N,N-dimethylacetamide alone
An adhesion test similar to that was conducted. The results are shown in Table 1. As is clear from the results in Table 1, the adhesive strength of the board method was almost the same as that of Example 1, but a large amount of distortion was observed in the bonded portion of the paper. Comparative Example 2 An adhesion test similar to Example 1 was conducted using a mixed solvent of 70% by weight N,N-dimethylacetamide and 30% by weight xylene. The results are shown in Table 1. As is clear from Table 1, although some distortion was observed in the bonded portion of the paper, the adhesive strength was weak.

[Table] Example 2 Polymetaphenylene isophthalamide with ηinh of 1.30 was obtained by the same polymerization operation as in Example 1. Calcium chloride remaining in the polymer after washing and drying was 0.8% by weight. This polymer is N,N-
An adhesive containing 4.96% by weight of polymetaphenylene isophthalamide, 76% by weight of N,N-dimethylacetamide, 19% by weight of toluene and 0.04% by weight of calcium chloride dissolved in a mixed solvent of 80% by weight of dimethylacetamide and 20% by weight of xylene. was prepared. Using this adhesive, the basis weight is 30g/m ² and the thickness is 52μm.
Aromatic polyamide paper was put together and the adhesion state was observed. Further, in the same manner as in Example 1, using an aromatic polyamide board, the board method adhesive strength was measured by the method of JISC-2103. The results are shown in the table. Comparative Example 3 The polymetaphenylene isophthalamide obtained in Example 2 was dissolved in N,N-dimethylacetamide to create an adhesive containing 4.96% by weight of polymer, 95% by weight of N,N-dimethylacetamide and 0.04% by weight of calcium chloride. was prepared and tested in the same manner as in Example 2. The results are shown in the table. As is clear from the table, although the adhesive strength was only slightly reduced, the bonded portion of the paper was highly distorted.

[Table] Example 3 108 parts of metaphenylenediamine was dissolved in 1000 parts of N-methyl-2-pyrrolidone, and after cooling to 0°C,
Mix powders of 182.7 parts of isophthalic acid chloride and 20.3 parts of terephthalic acid chloride, add them gradually under stirring, and react for about 1 hour to obtain a metaphenylene isophthalamide component of 90 mol% and a metaphenylene terephthalamide component of 10%. , an aromatic polyamide copolymer solution with ηinh of 1.86 was obtained. The resulting solution was neutralized with calcium hydroxide, poured into water to isolate the copolymer, and thoroughly washed to remove the solvent and calcium chloride, resulting in an aromatic polyamide copolymer containing substantially no calcium chloride. A polymer was obtained. The dried copolymer was dissolved in a mixed solvent of 60% by weight of N-methyl-2-pyrrolidone and 40% by weight of xylene to obtain a copolymer of 5.0% by weight, 57.0% by weight of N-methyl-2-pyrrolidone and 38.0% by weight of xylene. An adhesive was prepared. Using this adhesive, the basis weight is 25g/m ² and the thickness is 24μmm.
Aromatic polyamide paper with a thickness of 50 μm and an aromatic polyamide film with a thickness of 50 μm were adhered, and the condition of the bonded portion was observed. Furthermore, the adhesive strength of the aromatic polyamide board was measured in the same manner as in Examples 1 and 2. The results are shown in the table. Comparative Example 4 Aromatic polyamide copolymer obtained in Example 3
An adhesive consisting of 0.2% by weight, 59.9% by weight of N-methyl-2-pyrrolidone, and 39.9% by weight of xylene was prepared, and the same adhesion test as in Example 3 was conducted. The results are shown in the table. Although the adhesive strength was slightly lower than that of Example 3, the bonded portion had large distortions on both the paper side and the film side. Comparative Example 5 Aromatic polyamide copolymer obtained in Example 3
An adhesive was prepared containing 5.0% by weight, 93.5% by weight N-methyl-2-pyrrolidone, and 1.5% by weight xylene. An adhesion test similar to that in Example 3 was conducted using this adhesive. The results are shown in the table. As is clear from the table, the adhesive strength was not much different from that of Example 3, but the bonded portion had large distortions on both the paper side and the film side.

[Table] Example 4 Aromatic polyamide copolymer obtained in Example 1
An adhesive was prepared containing 9.99% by weight, 54% by weight NN-dimethylacetamide, 36% by weight xylene, and 0.01% by weight calcium chloride. This adhesive was used to coat both sides of a 50 μm thick aromatic polyamide film with a basis weight of 25 g/m ² and a thickness of 24 μm.
Aromatic polyamide paper of μm size was stitched together. The drying conditions during adhesion were 100°C for 30 minutes. The weight loss and dielectric breakdown voltage were measured when the bonded materials were heated at 300°C. The breakdown voltage is
Measured by the method described in JISC-2318. The results are shown in the table. Comparative Example 6 When producing the aromatic polyamide copolymer of Example 1, after isolating the copolymer, the copolymer was lightly washed and an adhesive was prepared with 4.1% by weight of calcium chloride remaining in the copolymer. provided. 9.59% by weight of this aromatic polyamide, 54% by weight of N,N-dimethylacetamide, 36% by weight of xylene,
An adhesive containing 0.41% by weight of calcium chloride was prepared and tested in the same manner as in Example 4. The results are shown in the table. Since the solvent N,N-dimethylacetamide remained even after the drying was completed, the loss on heating was large and the progress of thermal deterioration was also faster than in Example 4.

【table】

Claims (1)

[Scope of Claims] 1. Consisting of the following components (a), (b) and (c), or
Consists of (a), (b), (c) and (d) components, (a), (
b), (c)
and the content of component (a) relative to the total amount of component (d) is 0.5
~40% by weight, the content of component (d) is 0.2% by weight or less, and the content ratio of component (b) and component (c) is by weight
An aromatic polyamide adhesive characterized by having a ratio of 97:3 to 30:70. (a) An aromatic polyamide in which 90 mol% or more of the repeating units are represented by the following general formula. -NH-Ar ₁ -NHCO-Ar ₂ -CO- and/or -NH-Ar ₃ -CO- (However, Ar ₁ , Ar ₂ and Ar ₃ in the formula represent the same or different bifunctional aromatic rings. ) (b) N,N-dialkylformamide, N,N-
At least one polar organic solvent selected from the group consisting of dialkylacetamide, N-alkyl-pyrrolidone, tetraalkylurea, hesaalkylphosphoramide, and dialkyl sulfoxide. (c) A solvent that is compatible with the polar organic solvent (b) and is a non-solvent for the aromatic polyamide (a). (d) Alkali metal halides or alkaline earth metal halides.