JPS62141076A - Low-temperature soldering polyurethane insulated wire - Google Patents

Abstract

PURPOSE:To obtain a polyurethane insulated wire which has a reduced soldering temperature without decreasing the heat resistance and softening temperature, by applying a one-pack thermosetting polyurethane coating containing a specified catalyst on a conductor and baking it. CONSTITUTION:A 1,8-diaza-bicyclo(5.4.0)undecene-7-organic acid salt and an alkyltin maleate of formula IX, as catalyst, are added each in an amount of 0.1-5%, based on the solids of a coating, to a one-pack thermosetting polyurethane coating obtained by dissolving in an organic solvent three components comprising a blocked polyisocyanate compound of formula I, a polyester oligomer synthesized by the condensation through dehydration of glycerin or ethylene glycol with terephthalic acid or dimethyl terephthalate, and an alcohol-soluble copolyamide resin. This mixture is applied on a conductor to give an insulated wire. In the formulas, n is 2-3; R is a group of formulas II-V; R' is a group of formulas VI-VIII; m is 1-3.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to polyurethane insulation wires used for winding wires of magnetic head coils, small precision relay coils, etc., and in particular to the thermal characteristics of polyurethane insulation coatings. The present invention relates to a low-temperature soldering polyurethane insulated wire that can be soldered at a low temperature of 300°C or less without inhibiting the process.

[Conventional technology]

Polyurethane insulated wire is made by coating and baking polyurethane paint on the conductor, and has the property that it can be soldered as is without peeling off the urethane film, and is widely used in the light electrical field.
It is often used for winding small coils in communication equipment, etc.

Generally, polyurethane insulation paint is a thermosetting one-component paint made of an oligomer having an activated hydrogen atom, such as polyester, and having a molecular weight of 1.000 to 5,000.

A block polyin whose main component is polyether ester, epoxy, etc., is reacted with 3 moles of toluene diisocyanate as a crosslinking component, for example, 1 mole of trimethylolpropane, and the remaining incyanate groups are blocked with a blocking agent such as phenol. Cyanate is added, and the main component and crosslinking agent are dissolved in an organic solvent. In the process of applying and baking this paint onto the conductor,
When the temperature reaches 150°C or higher, the blocking agent of the blocked polyisocyanate dissociates and incyanate groups are generated. The generated incyanate group is highly reactive and reacts with coexisting oligomers containing activated hydrogen atoms, forming urethane bonds between oligomers, resulting in a three-dimensional network structure with excellent flexibility, adhesion, and electrical properties. Forms a polyurethane film.

[Problem that the invention seeks to solve]

The soldering temperature (depolymerization temperature of the urethane film) of conventionally commonly used polyurethane insulated wires is 360~
When a polyurethane insulated wire is immersed in molten solder, the time required for the urethane film to decompose is 2 to 3 seconds. If the temperature is lowered by more than 50 degrees, there is a drawback that the thermal properties of the urethane film inevitably deteriorate significantly.

In recent years, as electronics-related parts have become lighter, thinner, and shorter, the mounting density of printed circuit boards has also improved, and there is a strong desire for the emergence of ultrafine polyurethane wires that can be soldered at very low temperatures.

[Failure to solve the problem]

The present invention uses a material with a specific composition for the polyurethane insulation coating and the catalyst added thereto, thereby significantly reducing the soldering temperature without impairing the heat resistance and heat softening temperature of the polyurethane insulation coating. I was successful in doing so.

In order to lower the baking temperature of a polyurethane paint, the present inventors previously developed a thermosetting liquid polyurethane paint in which a blocked polyisocyanate and an oligomer having an activated hydrogen atom were dissolved in an organic solvent. -Proposed a polyurethane insulating paint containing a diaza-bicyclo(5,4,0)undecene-7-organic acid salt and an alkyltin mercaptide compound as a catalyst (JP-A-55-7376
Publication No. 5). As a result, we were able to achieve the intended purpose. The polyurethane insulated wire, in which the polyurethane paint was applied and baked onto the conductor, had a high soldering temperature of 380°C, and the immersion time in molten solder was long. is 1 to 2 seconds, and its application to ultrafine polyurethane insulated wires has been greatly limited.

In the present invention, in order to improve these drawbacks, various studies were conducted regarding the film forming agent and crosslinking agent, which are the main components of the polyurethane insulation paint, as well as the catalyst added thereto. As a result, as a film-forming agent, -fil,o(10~
5.000 polyester oligomer and an alcohol-soluble copolymerized polyamide resin as an armor extender,
As a crosslinking agent, a block polyisocyanate compound shown by the structural formula is used,
The catalysts to be added to the thermosetting liquid polyurethane paint prepared by dissolving these in an organic solvent include 1,8-diaza-bicyclo(5,4,0)undecene-7-organic acid salt and general formula m1-3 The problem was solved by using an integer of (in the formula, R'' represents an alkyl group having 1 to 8 carbon atoms).

The reaction system of polyurethane insulation paint is a two-step reaction,
One is a dissociation reaction of a block polyisocyanate compound, and is shown in the following formula (1).

Next, the reaction of formula (2) is a reaction between the free incyanate group generated by the reaction of formula (1) and the polyester oligomer, in other words, a crosslinking reaction between the polyester oligomers, and the crosslinked structure of the urethane film is Form. Furthermore, the long molecular weight alcohol-soluble polyamide resin is entangled in this crosslinked network, forming an interpenetrating network structure.

In the above two-step reaction, formula (1) is the rate-limiting reaction, and the catalyst that promotes this reaction is 1,8-diaza-bicyclo(
5,4,0) undecene-7-organic acid salt is also (2)
As a catalyst for the crosslinking reaction of the formula, an alkyltin maleate ester effectively acts. The alkyl tin maleate ester is represented by the above general formula, generally has a content of about 10 to 55 tin as metal tin, and is widely used industrially as a heat and light stabilizer for polyvinyl chloride mixtures. It is easily available as an organotin stabilizer.

[For production]

According to the present invention, 1,8-diaza-bicyclo(5,4,0)undecene-
7-Organic acid salt acts, about 50 da compared to blank
g Dissociation proceeds at low temperatures, producing free incyanate groups. Next, in the second stage curing reaction, due to the action of the second catalyst, alkyltin maleate,
The generated incyanate group immediately reacts with the activated hydrogen atom of the polyester oligomer to form a urethane bond,
Forms an intermolecular crosslinked structure. This means that in a reaction system to which a catalyst is added, the curing reaction is completed at a lower temperature.

The polyurethane insulating film of the present invention exhibits a crosslinked structure of mostly polyurethane bonds due to the action of the first and second catalysts. Polyurethane bonds undergo thermal decomposition (thermal depolymerization) at a temperature of 300°C, and the main reaction of the decomposition is as follows:
This is the reverse reaction of the urethane production reaction. Therefore, the obtained insulating film has low temperature soldering properties. In a reaction system in which these catalysts are not present, side reactions other than urethane bonds are likely to occur, and if a bond type such as urea bond is formed, low-temperature soldering properties can no longer be imparted. This is because when comparing the thermal decomposition reaction of urethane bonds with that of other urea bonds, the reaction proceeds much faster in the former bond type.

The reason why alcohol-soluble copolymerized polyamide resin was used in combination with polyester oligomer as a film-forming agent is that by adding a polyamide resin with a large molecular weight,
This is interposed between urethane crosslinking points, creating a bidirectional interstitial network structure, imparting sufficient mechanical strength to the film, and controlling the occurrence of side reactions other than urethane bonds during the curing reaction. This is also to provide the paint with functions as a flow control agent and a viscosity control agent.

The amounts of the first and second catalysts used in the present invention are:
It is limited to 0.1 to 5 inches each for the solid part of the paint.

This is because if the amount added is less than this, it is too small to achieve the desired purpose, and if it exceeds this amount, other properties other than soldering will be affected.

〔Example〕

Polyurethane insulation paints were prepared according to the compounding ratios shown in Table 1. 7
Table-1 Composition of polyurethane insulating paint Apply two coats of polyurethane insulating paint with the above composition on a copper wire with a conductor diameter of 0.1 mm.
Solderability and Q performance were measured for insulated wires coated and baked to a certain film thickness. Table 2 shows the characteristic results.

〔Effect of the invention〕

As shown in Table 2, the low temperature brazed polyurethane insulated wire of the present invention has a soldering temperature of 290 to 300°C, approximately 50 degrees lower than conventional polyurethane wires, and has comparable heat resistance and other properties. It is excellent.

Therefore, soldering can improve work efficiency and prevent thermal effects during the process, and is particularly effective when applied to ultra-fine wires with a conductor diameter of 0.03 mm or less, greatly improving the reliability of parts. obtain.

Claims (1)

[Claims] Structural formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ n = integer of 2 to 3 (In the formula, R is ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, R' has ▲mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas,
There are chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼. ), a polyester oligomer synthesized by a dehydration condensation reaction of glycerin or ethylene glycol and terephthalic acid or dimethylterephthalic acid, and an alcohol-soluble copolymerized polyamide resin, which are thermoset by dissolving them in an organic solvent. 1.8-diaza-picyclo(5.4.0) undecene- as a catalyst in one-component polyurethane paint.
7-Organic acid salts and general formula (R″) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ m = an integer of 1 to 3 (in the formula, R″ represents an alkyl group having 1 to 8 carbon atoms). A low-temperature brazed polyurethane insulated wire, characterized in that the alkyl tin maleate esters shown below are added in an amount of 0.1 to 5% to the solid part of the paint, and the mixture is applied and baked onto a conductor.