JPH0657210A - Polyurethane coating for electrical insulating wire - Google Patents

Abstract

PURPOSE:To provide a polyurethane coating which can be formed either into a varnish or into a film, enables, when baked on a wire, soldering thereof at a markedly low temp., can be greatly improved in the prevention of pinholing during stretching and thermal properties, and comprises a reaction product easily formable into a varnish by adding a suitable amt. of a catalyst to the reaction product diluted with a solvent, thus enabling the varnish to be formed by using only one material. CONSTITUTION:The polyurethane coating comprises a reaction product of a masked polyvalent isocyanate with a compd. having an active hydrogen atom(s), particularly a polyhydric alcohol, which product has, in the molecule thereof, a urethane bond segment(s) formed through an addition reaction of the isocyanate with the compd. having the active hydrogen atom(s) and a masked segment(s) wherein an isocyanate unit is still masked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane paint for electric insulated wires.

[0002]

It is known that polyurethane coatings are obtained by the reaction of polyhydric isocyanates such as toluene diisocyanate (TDI) with polyhydric alcohols such as trimethylolpropane (TMP). Since isocyanate is highly reactive, it is inconvenient to handle, and the isocyanate is masked with a masking agent such as phenol in order to temporarily protect the isocyanate reactive group and regenerate it as necessary so that it can be used for the reaction. Masking isocyanates (isocyanate regenerators) have also been proposed. To use masking isocyanate as a polyurethane paint (varnish for electric insulated wire), mix and dissolve masking isocyanate and a compound having active hydrogen (various types are used, such as polyester and polyester imide) in a solvent. , A catalyst is added to form a lacquer (varnish), which is baked onto a copper wire at a baking temperature to remove the masking agent, and the isocyanate reacts with a compound having active hydrogen to form a baked film. It has gained.

[0003]

However, in the above-mentioned prior art, the reaction between the polyvalent isocyanate and the polyhydric alcohol is carried out by adding the -OH group of the alcohol to the whole -NCO group of the isocyanate to form a urethane bond. The reaction between the isocyanate and the alcohol causes turbidity or gelation, and when coated on an electric wire, the alcohol volatilizes and becomes a coating that can withstand use. hard. Also, when a masking isocyanate is used, the masking agent added to the -NCO group of the isocyanate is all eliminated to form a urethane bond with a compound having active hydrogen.
In addition, the latter urethane varnish has a problem in temperature in solderability of the electric wire coating. That is, in recent years, in electrical equipment and the like, densification of parts thereof has progressed, lowering of soldering temperature is required from the viewpoint of thermal protection, and a soldering temperature of 300 ° C. or less is provided. However, the limit has already occurred in the conventional polyurethane paint by the above-mentioned method. Further, in the latter case, it is necessary to mix and dissolve different kinds of multi-materials such as separately prepared masking isocyanate and a compound having active hydrogen in a solvent, and the method is complicated.

[0004]

The present invention is a reaction product of a masking polyvalent isocyanate and a compound having active hydrogen, wherein the urethane is obtained by an addition reaction of an isocyanate and a compound having active hydrogen in one molecule. According to a polyurethane coating for an electric insulated wire, which comprises a reaction product having a bonding segment and a masking segment in which an isocyanate is still masked, in a preferred embodiment, the compound having active hydrogen is alcohol. The reaction product is a reaction product of the alcohol and the masking polyvalent isocyanate, and a urethane bond segment is formed based on the addition reaction of the regenerated isocyanate and the alcohol by elimination of the masking agent from the masking polyvalent isocyanate. Along with the isocyanate mask A polyurethane coating for an electric insulated wire, in which the reaction is stopped so as to leave the masking segment as it is, and when the masking polyvalent isocyanate is a bifunctional masking isocyanate, the reaction molar ratio of the alcohol is the bifunctional masking. 0.5 to 1.5 mol per 1 mol of isocyanate, and
When the masking polyvalent isocyanate is a trifunctional masking isocyanate, the reaction molar ratio of alcohol is
The amount of the functional masking isocyanate is 1.0 to 2.0 mol per mol of the functional masking isocyanate. The present invention relates to the polyurethane coating material for electric insulated wire, which is obtained by carrying out the reaction at a reaction temperature at which the alcohol is not eliminated after the urethane bond segment is added.

Examples of the isocyanate constituting the masking polyvalent isocyanate used in the present invention include tolylene diisocyanate (TDI), methyldiphenyl diisocyanate (MDI), hexamethylene diisocyanate (HMDI) and 80/20 tolylene diisocyanate ( T-80), 65/35 tolylene diisocyanate (T-65) and the like. Isocyanate dimers and trimers, HMDI derivatives, dimeryl diisocyanate (DDI), hydrogenated MDI (HMDI), HT
DI (hydrogenated TDI) and the like can also be used. These can use 1 type (s) or 2 or more types. Examples of the masking agent include xylenolic acid, phenol, alcohol, aromatic secondary amine and the like. These can use 1 type (s) or 2 or more types. Coronate 2503, which is already masked with a masking agent and is commercially available as a masking isocyanate.
(Nippon Polyurethane Co., Ltd.), Coronate MS-50 (Nippon Polyurethane Co., Ltd.), Coronate AP Stable (Nippon Polyurethane Co., Ltd.), CT Stable (Germany, Bayer Co.) can be used. These can use 1 type (s) or 2 or more types.

In the present invention, as the compound having active hydrogen, polyester, poly (oxypropylene ether)
Polyols, polyether polyols such as poly (oxyethylene-propylene ether) polyols, acrylic polyols, castor oil derivatives, tall oil derivatives,
Other active hydrogen group-containing compounds used for forming a polyurethane film such as a hydroxyl group-containing compound can be widely used, but alcohol is preferably used. Examples of the alcohol include trimethylolpropane (TMP), glycerin (G), hexane glycol (HG), pentaerythritol, tris or more polyhydric alcohols such as trishydroxyisocyanurate, and / or ethylene glycol, propylene glycol, neo. It is preferable to use a dihydric alcohol such as pentyl glycol or butanediol. These can use 1 type (s) or 2 or more types.

Next, a reaction example of the present invention will be described according to the following formula 1.

[0008]

[Formula 1]

In the above reaction example, the isocyanate group of the masking polyvalent isocyanate (A) is blocked by xylenolic acid. This masking polyvalent isocyanate (A) is reacted with glycerin (B). still,
These substances (A) and (B) are shown in a partially omitted form. In the above, formation of a reaction product by continuous synthesis of isocyanate, xylenolic acid as a masking agent, and glycerin cannot produce a desired product due to the reactivity of the isocyanate. It is necessary to mask the isocyanate group and react as described above. The use of masked polyisocyanates already masked as described above is recommended. In the reaction, the masking polyvalent isocyanate (A) and glycerin (B) are dissolved in the reaction solvent xylenolic acid in the above example and heated. In the general reaction, 3 mol of glycerin (B) is used, which is the number of mols to add the hydroxyl group of glycerin (B) to the isocyanate group by regeneration of the masking polyvalent isocyanate. Then, the amount is less than 3 mol, for example, 2 mol with respect to 1 mol of the trifunctional masking isocyanate (A). In the above reaction example, xylenolic acid as a masking agent is desorbed at 130 ° C. to regenerate the isocyanate (D) once. As shown in the above reaction example, when a smaller number of moles of alcohol than usual are reacted at a temperature at which alcohol is added to isocyanate, for example, at 160 ° C., a urethane bond segment to which alcohol is added is formed in one molecule. , A reaction product (E) having a masking segment which is not masked with a urethane bond and remains masked is obtained. The reaction is
It is carried out without catalyst. In the example of the reaction, for example, when the temperature is further heated to 180 ° C. or higher, the alcohol is desorbed, so the reaction is once stopped after the addition of the alcohol.

The characteristics of the present invention will be described from the above reaction examples. (1) The reaction product constituting the polyurethane coating material for electric insulated wires of the present invention comprises an isocyanate and a compound having active hydrogen in one molecule. Having a urethane bond segment by an addition reaction and a masking segment in which the isocyanate remains masked, and (2) in the reaction between the masking polyvalent isocyanate and the compound having active hydrogen, the compound having active hydrogen Use a mole number lower than usual with respect to the masking polyisocyanate, that is, the reaction ratio of the masking polyisocyanate and the compound having active hydrogen in the present invention is 0.5 to 1 mole of the bifunctional masking isocyanate. 1.5 mol, masking polyvalent isocyanate is trifunctional mask In the case of grayed isocyanate, the 3
Functional masking is preferably 1.0 to 2.0 mol per mol of isocyanate. (3) Masking The reaction is carried out at a reaction temperature at which the masking agent of the polyvalent isocyanate is eliminated, and at a reaction temperature at which the alcohol is not eliminated after the alcohol is once added to the isocyanate to form a urethane bond segment, (4) Masking A urethane bond segment is formed based on the addition reaction between the regenerated isocyanate and the alcohol due to the elimination of the masking agent from the polyvalent isocyanate, and the reaction is stopped so that the isocyanate segment remains masked as it is. (5) Preferably,
Performing the reaction in the absence of a catalyst, (6) As can be understood from the above, the present invention includes the elimination of masking and the addition reaction,
The present invention utilizes a competitive reaction with an alcohol addition reaction, and (7) preferably, the reaction is carried out in the same reaction solvent as the masking agent.

From the above reaction example, the characteristics of the polyurethane coating for electric insulated wire according to the present invention will be described. (1) In the conventional example, a masking isocyanate and an active hydrogen-containing compound, that is, at least two materials are dissolved and mixed in a solvent to form a catalyst. While it is necessary to add varnish to add varnish, in the present invention, the reaction product is diluted with a solvent,
A varnish can be easily formed by adding an appropriate amount of a catalyst. That is, since the reaction product having a urethane bond obtained in the above reaction example can be used to varnish by adding a catalyst and diluting a solvent, it is sufficient to use one material for varnishing. (2) Since the film has a urethane bond segment due to an addition reaction between an isocyanate and a compound having active hydrogen and a masking segment in which the isocyanate is masked, in one molecule, The temperature at the time of soldering can be made lower than that of the polyurethane coating by the method. By the way, in the case of the present invention, the soldering temperature is 280 ° C. and the low temperature solderability of 2 seconds or less is exhibited. (3) The film has only a urethane bond, which is different from the case where a conventional polyester, polyesterimide, epoxy, or the like contains an ester bond or an imide bond in addition to the urethane bond, From this aspect as well, the temperature at the time of soldering can be lowered, and soldering at a low temperature is possible. (4) In the present invention, the temperature at the time of soldering can be lowered as described above, and at the same time, the extension pinhole and thermal characteristics, that is, thermal shock resistance, deterioration resistance, and
It is also possible to significantly improve softening resistance. (5) In the above, a varnish can be formed from the masking isocyanate, alcohol, catalyst and solvent, but some varnishes separate, which causes a problem. Also, even if you try to form a baking film on the wire,
A film cannot be formed due to the scattering of alcohol. On the other hand, according to the present invention, as described above, the varnish can be easily formed, and when the wire is baked, an excellent urethane film having the above characteristics can be formed.

In the present invention, the reaction product can be easily varnished by diluting it with a solvent and adding an appropriate amount of a catalyst, and the varnish can of course be used alone. It may be used as a mixture with the existing polyurethane paint of.

[0013]

EXAMPLES Next, the present invention will be explained based on synthesis examples, examples and comparative examples. The electric wire test method in the following examples was performed in accordance with JIS-3003.

Synthesis Examples 1 to 7 The reaction products according to the present invention were synthesized according to the formulations shown in Table 1. A 4-necked flask equipped with a stirrer, a condenser, a thermometer, and a thermocouple was charged with the amounts of xylenenolic acid (XYL), cresylic acid, and polyhydric alcohol shown in Table 1,
The amount of masking xocyanate shown in Table 1 was completely dissolved at 100 ° C. or lower, the temperature was raised from 100 ° C. to 160 ° C. in 2 hours, and the reaction was carried out at 160 ° C. for 3 hours. 2 (SN No. 2) (however, cresylic acid was used in Synthesis Examples 1 and 3) to prepare a 45% masking isocyanate / polyol compound.
The viscosity shown in Table 1 was measured with a B type viscometer.

Examples 1 to 7 Using the reaction products obtained in the above synthesis examples, as shown in Table 2, 1% of 8% lead octylate as a catalyst was added to each 1000 g of the reaction products. 4.5 g and 4.5 g of butylbenzylamine 1% were added, and the mixture was diluted to 25% with cresylic acid / xylene = 7/3 (560 g / 231 g) to form a paint (each total weight was 1800 g). The solutions obtained in Synthesis Examples 1 and 2 are slightly tinged, but become transparent when they are made into 25% paint as described above. The resulting paint was applied to the Kuhara Seisakusho horizontal electric prototype reactor (furnace length 3
m) at a temperature of 320 ° C. at the inlet and 340 ° C. at the outlet,
A round copper wire having a diameter of 0.20 mm was adjusted and baked at a speed of 80 m / min to a JIS Class 2 finished outer diameter by drawing 6 times of felt to obtain an electrically insulated electric wire. The characteristics of this electric wire were measured by the JIS method, and the results are shown in Table 4.

Examples 8 to 15 As shown in Table 3, the varnishes (paints) obtained in Examples 1 to 7 and the existing low temperature soldering paint TPUK5-13.
2, TPNK5-5 (both manufactured by Tokushu Paint Co., Ltd.)
It was blended at 1/1 in terms of resin content to obtain a paint. The resulting paint was applied to the Kuhara Seisakusho horizontal electric prototype reactor (furnace length 3
m) at a temperature of 320 ° C. at the inlet and 340 ° C. at the outlet,
A round copper wire having a diameter of 0.20 mm was adjusted and baked at a speed of 80 m / min to a JIS Class 2 finished outer diameter by drawing 6 times of felt to obtain an electrically insulated electric wire. The characteristics of this electric wire were measured by the JIS method, and the results are shown in Table 5.

Comparative Examples 1 to 4 General-purpose polyurethane paints TPUF2-25NC, TPU
K5-13 / 25, TPUK5-5 / 25, TPUK
5-7.25 (all manufactured by Tokushu Paint Co., Ltd.) was baked in the same manner as in Example 1 to obtain an electrically insulated electric wire. The characteristics of this electric wire were measured by the JIS method, and the results are shown in Table 6.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[0024]

EFFECTS OF THE INVENTION According to the present invention, (1) in the conventional example, it is necessary to dissolve and mix a masking isocyanate and an active hydrogen-containing compound, that is, at least two materials in a solvent, and to add a catalyst to form a varnish. In the present invention, the reaction product is diluted with a solvent,
A varnish can be easily formed by adding an appropriate amount of a catalyst. That is, since the reaction product having a urethane bond obtained in the above reaction example can be used to varnish by adding a catalyst and diluting a solvent, it is sufficient to use one material for varnishing. (2) Since the film has a urethane bond segment due to an addition reaction between an isocyanate and a compound having active hydrogen and a masking segment in which the isocyanate remains masked in one molecule, the above-mentioned conventional The temperature at the time of soldering can be made lower than that of the polyurethane coating by the method. By the way, in the case of the present invention, the soldering temperature is 280 ° C. and the low temperature solderability of 2 seconds or less is exhibited. (3) The film has only a urethane bond when alcohol is used as a compound having active hydrogen, and an ester bond or an imide bond in addition to the urethane bond when a conventional polyester, polyester imide, epoxy or the like is used. This is different from the case of containing Al. Also from this aspect, the temperature at the time of soldering can be lowered, and soldering at a low temperature is possible. (4) In the present invention, the temperature at the time of soldering can be lowered as described above, and at the same time, the extension pinhole and thermal characteristics, that is, thermal shock resistance, deterioration resistance, and
It is also possible to significantly improve softening resistance. (5) Masking Isocyanate and polyhydric alcohol are used to form a varnish to obtain a baked film on a copper wire.
In varnishing, nigori and separation (for example, separation of glycerin, etc.) occur, and the film formation due to scattering is impossible due to the low molecular weight of alcohol during baking. On the other hand, according to the present invention, it is possible to form a varnish or a film by introducing both into one molecule through a chemical bond, and when baked on a wire, an excellent urethane film having the above characteristics is formed. We were able to.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Sakuma 3-9-33 Sakae Honjo City Saitama Prefecture Honjo Factory Co., Ltd. (72) Inventor Tetsuhide Kakukura 3-9-33 Sakae Honjo City Saitama Prefecture Tokutei Paint Stock Company Honjo Factory

Claims (3)

[Claims] 1. A reaction product of a masking polyvalent isocyanate and a compound having active hydrogen, wherein:
A polyurethane coating material for electric insulated wire, comprising a reaction product having a urethane bond segment by an addition reaction of an isocyanate and a compound having active hydrogen and a masking segment in which the isocyanate is masked. 2. The compound having active hydrogen is alcohol,
The reaction product according to claim 1, which is a reaction product of the alcohol and a masking polyvalent isocyanate, and is a urethane based on an addition reaction between a regenerated isocyanate and an alcohol by elimination of a masking agent from the masking polyvalent isocyanate. The polyurethane coating composition for an electrically insulated wire according to claim 1, wherein the reaction is stopped so that the isocyanate segment remains the masked segment when the bonding segment is formed. 3. When the masking polyvalent isocyanate is a bifunctional masking isocyanate, the reaction molar ratio of the alcohol is 0.5 to 1.5 mol with respect to 1 mol of the bifunctional masking isocyanate, and the masking polyvalent isocyanate is In the case of trifunctional masking isocyanate,
The reaction molar ratio of alcohol is 1.0 to 2.0 mol per 1 mol of the trifunctional masking isocyanate and the reaction temperature at which the masking agent of the masking polyisocyanate is desorbed in the same reaction solvent as the masking agent. And, and
The polyurethane coating material for electric insulated wire according to claim 2, wherein the reaction is carried out at a reaction temperature at which the alcohol is not eliminated once the alcohol is added to the isocyanate to form the urethane bond segment.