JPS6351196B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an insulated wire obtained using a new cresol-based solvent-soluble polyamideimide. An object of the present invention is to provide an inexpensive insulated wire with well-balanced heat resistance, flexibility, freon resistance, and abrasion resistance. BACKGROUND ART Currently, insulated wires using polyester resins as electrical insulation coating compositions are often used because they have relatively well-balanced mechanical properties, electrical properties, heat resistance, etc. However, in recent years, in order to reduce the size and weight of electrical equipment, there has been a demand for insulated wires with even better heat resistance, freon resistance, and abrasion resistance. Insulated wires with good heat resistance, freon resistance, and abrasion resistance include highly heat-resistant wires coated with compositions such as polyimide and polyamideimide. ) and other special solvents, making the resin itself expensive, which poses a major problem in terms of cost. Therefore, in order to improve the heat resistance of polyester-based insulated wires,
An insulated wire using tris(2-hydroxyethyl) isocyanurate (THEIC) and so-called THEIC-modified polyesterimide containing an imide group has been proposed. However, although THEIC-modified polyesterimide has significantly improved heat resistance compared to polyester, it has drawbacks in abrasion resistance and freon resistance, and is not as good as polyamide-imide. Therefore, many studies have been conducted to solubilize polyamide-imide varnish, which has excellent heat resistance, in general-purpose solvents such as cresol, and it has been proposed to use lactam etc. as a reaction component (for example, Japanese Patent Publication No. 46-29730 , Special Publication No. 49-30718, Special Publication No. 1973
- No. 20993, Special Publication No. 53-47157). However, cresol-soluble polyamide-imide in which lactam or the like is used in combination is actually significantly inferior to the current polyamide-imide in terms of heat resistance, particularly heat softening temperature. In order to improve this thermal softening temperature, it is described in JP-A-52-40599 that a polyisocyanate containing an isocyanurate ring is used as a part of the isocyanate compound. In the composition shown, although the thermal softening temperature is improved, the flexibility is significantly reduced, and no product of practical value has been obtained. Specifically, if the baking time is long, the heat softening temperature is good, but the flexibility decreases, and if the baking time is short, the resin does not have a high molecular weight, and the heat softening temperature and flexibility decrease. Sexuality decreases. The present inventors have conducted extensive studies on solubilizing polyamide-imide resin compositions (for example, Hitachi Chemical HI-404) currently commercially available as NMP-based solutions in cresol-based solvents, and as a result, have completed the present invention. Ivy. The present invention has a residual amount of isocyanate groups of 10 to 70%.
isocyanurate ring-containing polyisocyanate,
An aromatic diisocyanate, a lactam, and a polycarboxylic acid containing an acid anhydride group are mixed into a cresol-based solvent, with the isocyanurate ring-containing polyisocyanate being 1 to 30 equivalent % of the total isocyanate amount, and the lactam being 50 to 70 equivalent % of the total isocyanate amount. The present invention relates to a polyamide-imide-coated insulated wire coated with a composition containing a polyamide-imide resin obtained by reaction in a polyamide-imide resin. The polyisocyanate containing an isocyanurate ring used in the present invention is obtained by trimerizing isocyanate groups, and this reaction is carried out in the presence of a solvent that does not react with isocyanate groups, so that the reaction can proceed effectively. It is desirable to use a trimerization catalyst of isocyanate groups. As long as the solvent dissolves the isocyanate as a raw material, aliphatic and aromatic hydrocarbons, halogenated aromatic hydrocarbons, esters, ketones, ethers, ethylene glycol monoalkyl monoacetate solvents, dimethyl It can be arbitrarily selected from sulfoxides, etc. Examples of trimerization catalysts for polyisocyanate compounds include alkali metal acetate, metal salts and organometallic compounds such as iron, magnesium, nickel, zinc, tin, lead, vanadium, and titanium, N-methylmorpholine, 1,8-diazabicyclo(5 ,4,
0) Mannitz base of phenols such as undecene-7,2-(dimethylaminomethyl)-4,6-dimethylphenol, tertiary amines such as N,N-bis-(dimethylaminoethyl)-N-methylamine, etc. can be used, there are no particular restrictions. The reaction temperature for trimerizing the polyisocyanate compound is, for example, in the range of 50 to 160°C. The actual trimerization reaction of polyisocyanate compounds is complex and does not necessarily selectively produce only isocyanate adducts containing only one isocyanurate ring in one molecule, and unreacted isocyanate and isocyanurate rings are A mixture with two or more isocyanate adducts in one molecule is obtained. This mixture can also be used in the present invention. The amount of catalyst and reaction temperature can be determined depending on the number of isocyanurate rings contained in the isocyanate adduct, but in general, let us take as an example the case where the reaction is carried out in such a way that the proportion of residual isocyanate groups is about 50%. The preferred reaction temperature is 0.01 to 2% by weight of the tertiary amine based on the isocyanate, and the reaction temperature is 70 to 160°C. As a raw material for polyisocyanate containing an isocyanurate ring, any aliphatic, alicyclic, or aromatic diisocyanate compound may be used as long as it forms an isocyanurate ring. Group diisocyanates, particularly 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, tolylene diisocyanate, and xylylene diisocyanate are preferred, and a mixture of these may be used. A polyisocyanate synthesized in advance may be used, or a polyisocyanate stabilized with a blocking agent such as phenol or cresol may be used to avoid deterioration over time. Isocyanurate ring-containing polyisocyanates can be used with different numbers of isocyanurate rings depending on the purpose;
In view of flexibility, etc., the content of residual isocyanate groups is in the range of 10 to 70% (assuming the content of isocyanate groups in the diisocyanate to be 100). If it is too large, the heat resistance will decrease, and if it is too small, the flexibility will decrease. The amount of these polyisocyanates used is important as well as the amount of lactam used, which will be described below. If the amounts used are incorrect, it will be impossible to produce a practical heat-resistant resin and, therefore, it will not be possible to obtain a practically usable insulated wire. The isocyanurate ring-containing polyisocyanate contains 1 to 30 polyisocyanates in all isocyanate components.
It should be equivalent %. If it is too large or too small, a well-balanced property of heat resistance and flexibility will not be exhibited. If the amount is too large, the degree of branching will increase and gelation may occur during synthesis. Similarly, the lactam, which is an important raw material for cresol solubilization, can generally be any lactam as long as it reacts with isocyanate groups or acid anhydride groups in a cresol solvent and becomes soluble. Considering the nature and cost aspects,
ε-caprolactam is preferred. It is not necessary to add isocyanate groups in equivalent amounts (ε-caprolactam is considered to be difunctional. Therefore, 1 mole is 2 equivalents), and if heat resistance, flexibility, and solubility are comprehensively considered, 50~ of isocyanate equivalent
70 equivalent% is good. Specifically, 50 to 70 equivalents of the total isocyanate equivalents are contained in the resin bone core, which is the reaction product.
may be contained. If the content in the resin bone core is too high or too low, it will not be possible to obtain an insulated wire that has a good balance between heat resistance and flexibility, and has excellent freon resistance and abrasion resistance. Preferred aromatic diisocyanates include 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, tolylene diisocyanate, and xylene diisocyanate. A mixture of these aromatic diisocyanates may be used. As the carboxylic acid containing an acid anhydride group, for example, compounds represented by the general formulas () and () can be used, and any carboxylic acid containing an acid anhydride group that reacts with an isocyanate group or a derivative thereof may be used. There are no restrictions. Add acid anhydride group if necessary (R=H, alkyl group, phenyl group, etc.) X=-CH ₂ -, -CO-, -SO ₂ -, -O-, etc.)
Pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, bicyclo[2,2,2] to the extent that the solubility of some of the carboxylic acids contained is not impaired. ―
It may be replaced with a carboxylic dianhydride such as oct-(7)-ene-2:3,5:6-tetracarboxylic dianhydride. In general, trimellitic anhydride is preferred in consideration of heat resistance, cost, etc. From the viewpoint of heat resistance, the amounts of the isocyanate component and acid component to be used are preferably selected such that the ratio of isocyanate groups to carboxyl groups and acid anhydride groups is 1.5 to 0.7. In order to obtain a resin with a high molecular weight that is preferable for properties of insulated wires, a value around 1.0 is particularly preferable. As the cresol solvent, phenols other than cresol, xylenol, etc. can be used, and mixed solvents may also be used. Some of the synthesis solvents include aromatic organic solvents with high boiling points, such as xylene,
NISSEKIHISOL-100, 150, cellosolve acetate, etc. can also be used. In the synthesis, the reaction raw materials may be charged at the same time, or some of the raw materials may be added later, but preferably all the isocyanate components, lactam and cresol solvent are charged and reacted at 160 to 190°C for 1 to 3 hours. Thereafter, an acid anhydride group-containing polycarboxylic acid is added, and the reaction is further continued at 200 to 220°C for 10 to 20 hours. The progress of the reaction can be determined by observing the generated carbon dioxide gas bubbles and the viscosity of the solution. In order to avoid deterioration over time and to proceed with a uniform reaction, it is also effective to dissolve the isocyanate component in a cresol solvent in advance.
In order to advance the reaction sufficiently, catalysts such as tertiary amines and organic metal salts such as tin octenoate and cobalt octenoate can also be used. The cresol-soluble polyamideimide thus obtained was further treated with a cresol solvent to reduce the resin content to 20%.
Diluted to ~40% by weight. In this case, xylene, NISSEKI HISOL-100 (trademark of aromatic hydrocarbons manufactured by Nippon Petrochemical Co., Ltd.), cellosolve acetate, dimethylformamide, etc. may be used in combination as a co-solvent. A portion of other cresol-soluble resins may be added as necessary. Using the varnish thus prepared, an insulated wire can be obtained. The polyamide-imide coated insulated wire according to the present invention exhibits good heat resistance, freon resistance, abrasion resistance, and flexibility. The present invention will be explained using comparative examples and examples.
The manufacturing conditions for the insulated wires in the comparative examples and examples are as follows. Furnace: Vertical furnace with furnace height of 4.5m Furnace temperature: Inlet/center/outlet = 260℃/360℃/420
℃ (Comparative example 2 only 300℃/350℃/400℃) Die diameter (mm): 1.075×2, 1.100×2, 1.125
× 2, 1.150 × 2 Wire diameter: 1.0 mm Pulling speed: 6 to 8 m/s (Comparative example 2 only 9 to
13m/sec) Comparative Example 1 (1) Synthesis components of aromatic diisocyanate trimer Gram tolylene diisocyanate 600 Xylene 600 2-dimethylaminoethanol (catalyst) 1.8 The above ingredients were mixed in a 4-mouth tube equipped with a thermometer and a stirrer. Place it in a flask and raise the temperature to 140℃ in a nitrogen stream.
At the same temperature, the content of isocyanate groups (initial concentration:
48% by weight) was reduced to 25% by weight. The infrared spectrum of this substance is
Absorption of isocyanurate rings was observed at 1.710 cm ^-1 and 1.410 cm ^-1 , and absorption of isocyanate groups was observed at 2.260 cm ^-1 . (2) Cresol-soluble polyamide-imide coated insulated wire

[Table] Place the above ingredients except trimellitic anhydride into a four-necked flask equipped with a thermometer, stirrer, and fractionator tube, raise the temperature to 180°C in a nitrogen stream, and conduct the reaction for 90 minutes. Next, trimellitic anhydride is added and the temperature is raised to 210°C. The reaction was maintained at 210°C for 15 hours. Cresol resin concentration 30% by weight
A varnish was obtained. The viscosity was 250 poise. The reduced viscosity of the thus obtained resin measured in dimethylformamide was 0.23. In the infrared absorption spectrum, an imide group absorption was observed at 1.780 cm ^-1 and an imide group absorption at 1.650 cm ^-1 . An insulated wire was prepared using this varnish. Comparative Example 2 An insulated wire was prepared using a tris(2-hydroxyethyl)isocyanurate-modified polyester imide varnish (trade name: ISOMID) manufactured by Schenectaday. Example 1

[Table] A varnish was synthesized in substantially the same manner as in Comparative Example 1 (2) and adjusted to a resin concentration of 30% by weight using cresol. The viscosity of this material was 260 boads. The reduced viscosity of the thus obtained resin measured in dimethylformamide was 0.21. In the infrared absorption spectrum, imide group absorption was observed at 1.780 cm ^-1 and amide bond absorption was observed at 1.650 cm ^-1 . An insulated wire was prepared using this varnish. Example 2

[Table] A varnish was synthesized in substantially the same manner as in Comparative Example 1 (2) and adjusted to a resin concentration of 30% by weight using cresol. The viscosity of this material was 260 boads. The reduced viscosity of the thus obtained resin measured in dimethylformamide was 0.23. In the infrared absorption spectrum, both imide group absorption at 1.780 cm ^-1 and amide group absorption at 1.650 cm ^-1 were observed.
An insulated wire was prepared using this varnish. Example 3

[Table] Cyanate

[Table] A varnish was synthesized in substantially the same manner as in Comparative Example 1 (2) and adjusted to a resin concentration of 30% by weight using cresol. The viscosity of this material was 250 boads. The reduced viscosity of the thus obtained resin measured in dimethylformamide was 0.22. In the infrared spectrum, the imide group absorption at 1.780 cm ^-1 and 1.650
Absorption of the amide group at cm ^-1 was observed in both cases. An insulated wire was prepared using this varnish. Table 1 shows the characteristics of the insulated wire obtained as described above.

[Table] Insulated wires and refrigerating machine oil (RM-
25F) and seal. Next, vacuum degassing (approximately 10
mmHg) and heat to 100°C. After keeping it warm for 30 minutes, it was cooled, and the same amount of Freon gas (R-22) as the used refrigeration oil was inhaled, and the treatment was continued at 125°C for 7 days. After this, the mixture is slowly cooled to room temperature and the Freon gas is gently removed. Immediately after removing the Freon gas, wipe off the oil adhering to the sample and heat it at 130°C for 10 minutes. The insulated wire thus obtained is evaluated for appearance, breakdown voltage, hardness, etc., and is comprehensively judged to be good or bad. (◎...Good, 〇...Slightly good, △...Difficulties) Compared to the insulated wire obtained from the cresol-soluble polyamide-imide synthesized using ε-caprolactam in Comparative Example 1 in an amount approximately equivalent to the total amount of isocyanate, the isocyanurate ring Polyisocyanate and ε-
The insulated wires of Examples 1 to 3, which were obtained from varnishes synthesized with careful consideration of caprolactam contents, were all excellent in heat resistance (thermal softening temperature), flexibility, abrasion resistance, and freon resistance. It can be seen that It also has superior thermal shock resistance, abrasion resistance, and freon resistance compared to insulated wires using tris(2-hydroxyethyl) isocyanurate-modified polyesterimide (Comparative Example 2), which is currently popular as an enamel varnish for F-class wires. It is shown that

Claims (1)

[Scope of Claims] 1. Isocyanurate ring-containing polyisocyanate, aromatic diisocyanate, lactam, and acid anhydride group-containing polycarboxylic acid having a residual amount of isocyanate groups of 10 to 70%; 1 of the total isocyanate amount
~30 equivalent% lactam, 50% of total isocyanate amount
A polyamide-imide coated insulated wire coated with a composition containing a polyamide-imide resin obtained by reacting the polyamide-imide resin in an amount of 70 equivalent% in a cresol solvent. 2 The isocyanurate ring-containing polyisocyanate is 4,4'-diphenylmethane diisocyanate,
4,4′-diphenyl ether diisocyanate,
Claim 1 is an isocyanurate ring-containing polyisocyanate obtained from tolylene diisocyanate or xylylene diisocyanate.
Polyamide-imide coated insulated wire as described in . 3. The polyamide-imide coated insulated wire according to claim 1 or 2, wherein the lactam is ε-caprolactam. 4. Claim 1, wherein the polycarboxylic acid containing an acid anhydride group is trimellitic anhydride.
The polyamide-imide coated insulated wire according to item 1, 2 or 3.