JPS5853674B2 - UV curing varnish - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultraviolet curing varnish used, for example, for insulation coating of insulated wires.

Conventional varnishes, especially those used in the manufacture of insulated wires, are solvents,
For example, it contains about 40 to 60 parts by weight of expensive substances such as toluene, xylene, metacresol, phenol, 2-methylpyrrolidone, or dimethylformamide, and safety and health is caused by the volatilization of these solvents during the manufacturing process of insulated wires. It has the disadvantage of having the above problem.

In other words, conventional insulated wires use solvent-based varnish and are heated to high temperatures (approximately 3
Usually 6 to 12
It is manufactured by repeating the process of applying varnish and drying and curing, but the solvent only dissolves the base resin, so it completely evaporates during the drying and curing, and the solvent In addition to emitting a characteristic strong odor, it also has drawbacks in terms of safety and health, as well as resource conservation.

The object of the present invention is to obtain a varnish that does not require a solvent and therefore eliminates the above-mentioned drawbacks, particularly an ultraviolet curing varnish suitable for manufacturing insulated wires.

The ultraviolet curable varnish according to the present invention has the general formula (where R
1 is -H or -C) (, , , R2 and square are residues of a dibasic acid, and b R3 is a residue of a polyesterimide polyol.

50 to 95 parts (parts by weight, hereinafter referred to as parts by weight) of a compound represented by the formula (2), and containing 30 moles or more of a compound whose formula is a residue of an unsaturated dibasic acid. (indicated by
It can also be easily obtained by blending a desired amount of polymerization catalyst.

The prepolymer (4) has the general formula (where Rg is a glycol residue, RO is a dibasic acid residue, and RI is a residue of a functional imide compound at the molecular terminal).

Further, l is 0 or a manufacturing number of 1 to 10, and m is an integer of 1 to 5.

) and 1 mol of oligoesterimide polyol (a) CO\ and two rings represented by the general formula R2'0 - CO
/ 2 moles of the base acid anhydride (b) are reacted to form the compound (a) in which the molecular terminal has a carboxyl group.

When obtaining the compound, the dibasic acid (b) is
It is preferable that 0 mole φ or more is maleic anhydride.

If it is less than 30 mol φ, the heat resistance of the cured product will be poor, which is not preferable.

One mole of the terminal carboxyl compound thus obtained can then be reacted with two moles of glycidyl (meth)acrylate to form a prepolymer represented by the above general formula (4).

The prepolymer (4) thus obtained has an unsaturated group derived from maleic acid and a (meth)acryloyl group at its molecular ends.

These two types of unsaturated groups each form a cross-linked bond that is polymerized by UV irradiation, and the resulting cross-linked polymer has a structure with multiple cross-linked parts and has extremely excellent thermal stability. Become something.

It is known that vinyl hexamer polymers such as polystyrene and polymethyl methacrylate depolymerize at high temperatures.

The ultraviolet curable varnish of the present invention has a reaction mechanism in which it is cured by polymerization of vinyl groups, and this crosslinked polymer is particularly intended for electric wire materials that require heat-resistant stability, and has been imparted with heat resistance. There must be.

As mentioned above, the prepolymer (4) used in the present invention is a crosslinked polymer having multiple crosslinks, and these crosslinks are derived from two types of unsaturated groups, which makes it stable in heat resistance. It is thought that it contributes to sex.

Therefore, the synthesis of the prepolymer used in the present invention is preferably carried out according to the reaction described above. The oriconysterimide polyol represented by the general formula (b) is obtained from glycol, dibasic acid, and a functional imide compound at the molecular terminal. be able to.

The molecular terminal functional group of the imide compound is -COOH
and/or -OH is preferred, and the following compounds can be mentioned as those suitably used.

(In the formulas, all of RIO represent organic group residues. The imide compounds of formulas (1) to (9) above are tricarboxylic acid anhydrides (a) represented by the specified formula, dianhydrides of the general formula (b) and monoaminomonocarboxylic acid (c) each represented by the general formula H2N-R7-C0OH, and the general formula H2N-R8
It can be obtained by reacting a monoamino monoalcohol represented by -OH) with a diamine (e) represented by the general formula H2N-NH2.

Also, the above formulas (3), (7), (8) and (9
In the imide compound of ), a diisocyanate (he) represented by the general formula 0CN-U-NCO can be used in place of the diamine (e).

Each of the above-mentioned components will now be explained.

First, the component (a) is trimellitic anhydride, 3.4.
4' diphenyltricarboxylic anhydride, 3,4,4' diphenyl ethertricarboxylic anhydride, ethylenetricarboxylic anhydride, 2,3,6'-naphthalenetricarboxylic anhydride, etc. are used.

Ingredient (b) is pyromellitic dianhydride, 3.3'
・4,41-diphenyltetracarboxylic dianhydride, 2
・2', 3, 31-diphenyltetracarboxylic dianhydride, 2, 3, 6, 7 naphthalene tetracarboxylic dianhydride, 2, Z-bis (3, 4-dicarboxyphenyl) propani dianhydride, pig Dientetracarboxylic dianhydride and the like are used.

Component (c) includes gamma-aminobutyric acid, anthranilic acid, P-aminobenzoic acid, m-aminobenzoic acid, β-
Examples include aminopropionic acid.

Ingredients) include 2-amino-1-butanol, 2-amino-2-methyl-1-propatol, 2-aminoethane/
-/L', 3-amino-1-propanol, and the like.

Ingredients (e) include meta-phenylene diamine, ortho-phenylene diamine, para-phenylene diamine, 2-4-
Toluenediamine, 2,6-toluenediamine, and 4,4'-diaminodiphenylsulfone, 4,4'-
Diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'diaminodiphenyl, 4,4-
Diaminobenzophenone and their hydrogenated products, hexamethylenediamine, ethylenediamine, diaminopropane,
Examples include 2,2-dimethylpropylene diamine.

The diisocyanate (F) that can be used in place of the component (E) is, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, meta-phenylene diisocyanate, hydrogenated meta-phenylene diisocyanate. , xylylene diisocyanate, hexamethylene diisocyanate, etc.

The imide compounds of the formulas (1) to (9) are prepared by selecting the above-mentioned components and formulations from the formulas, and using a usual solvent such as m-cresol, dimethylformamide, dimethylacetamide, or adding xylene, toluene, anisole, etc. to the above-mentioned solvent. It can be obtained by carrying out a condensation reaction in a mixed solvent.

The oriconister polyol represented by formula (a) is represented by the above formula (
It can be obtained by carrying out a normal esterification reaction from the imide compounds of 1) to (9), the glycol, and a dibasic acid.

At this time, the functional group (-
The degree of polymerization l and/or m can be changed by adjusting the blending of glycol and/or dibasic acid depending on the type and number of COOH and/or -OH).

The value of l and/or m corresponds to the properties of the prepolymer (4) finally obtained, such as solubility in monomers or varnish viscosity that does not cause any inconvenience during work. , usually l is Ol or 1 to 10, m
may be selected from the range of 1 to 5.

The following can be listed as the above-mentioned glycols and dibasic acids.

That is, glycols include ethylene glycol, diethylene glycol, propylene gelylcol, dipropylene glycol, neopentyl glycol, hydrogenated bisphenol A, etc., and dibasic acids include phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid,
and its anhydrides, terephthalic acid, isophthalic acid, and lower alkyl esters of the acids, adipic acid, cepatic acid, maleic acid, fumaric acid, etc.

As described above, the resulting polyol represented by the general formula (a) is obtained by reacting 1 mole of the polyol with 2 moles of the dibasic acid anhydride (b) to form a carboxy compound at the molecular terminal, and then The desired prepolymer (4) can be obtained by reacting 2 moles of glycidyl (meth)acrylate.

In addition, in the reaction to obtain the above prepolymer, in order to quickly esterify the epoxy group of glycidyl (meth)acrylate, for example, a tertiary amine (such as benzyldimethylamine), a metal soap or chelate such as aluminum or zinc is used. It is preferable to add a small amount of a compound or the like, and to add a small amount of a polymerization inhibitor (eg, hydroquinone, quinhydro, etc.) to prevent kelization.

The prepolymer (4) thus obtained is viscous at room temperature and can be used as is if it shows fluidity when slightly warmed, but in many cases it is reactive. It is preferable to add a diluent as a diluent since it has the advantage that the viscosity can be adjusted more easily and the properties of the cured product can also be adjusted.

Examples of monomers having one or more unsaturated groups in the molecule include styrene, vinyltoluene, acrylontolyl, vinyl acetate, (meth)acrylic acid and its alkyl esters, toehamethyl (meth)acrylate, propyl (meth)acrylate, ) acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, etc.], and glycol mono(meth)acrylates (e.g., hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, etc.) , and di(meth)acrylates of glycols [e.g., ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, diprolene glycol di(meth)acrylate, etc.], and further diallyl ( iso)phthalate,
triallyl shea slate, triallyl trimellitate,
glycidyl (meth)acrylate, divinylbenzene,
Examples include vinylpyrrolidone, which can be used as a single monomer or as a mixture of several monomers.

These monomers are prepolymers of general formula 1 50-95
What is necessary is just to mix|blend 50-5 weight part with respect to weight part.

This blending amount is based on the monomer and prepolymer (4
), and furthermore, it may be selected based on the characteristics of the cured product finally obtained and the viscosity of the varnish from the processing surface.

Among the above-mentioned 7-mers, high boiling point (e.g. 90'C/1
Since the present invention is related to cold cure technology, varnishes using varnishes with a temperature of 0 mmHg or higher are free from volatilization of varnish components, resulting in low odor or odorless varnishes, which is extremely desirable in terms of resource conservation and health and safety. .

In addition, for example, if the varnish has a low molecular weight such as styrene and has a strong tendency to reduce the viscosity of the varnish, but on the other hand, it has an odor even at room temperature, it is necessary to maintain it at a low temperature depending on the viscosity of the varnish. is preferred.

In addition, in the prepolymer (4), if a highly polar heptanomer such as vinylpyrrolidone is used to make it particularly easy to dissolve, for example, a prepolymer with a large amount of imide, the prepolymer can be easily made into a varnish. can be converted into

Furthermore, when a material that is easily oxidized, such as tetrahydrofurfuryl (meth)acrylate, is used in combination, an air-drying varnish can be used.

As described above, the solvent-free varnish according to the present invention is particularly excellent as a varnish for insulated wires, and can meet a wide range of requirements, such as characteristics suitable for the application and workability, with a large degree of freedom.

It goes without saying that it can be used for things other than electric wires.

The varnish obtained as described above can be directly irradiated with S ultraviolet rays, but it can be rapidly cured by adding a photosensitizer.

Examples of the photosensitizer include carbonyl compounds such as benzoin and its derivatives (for example, benzoin methyl ether, benzoin ethyl ether, etc.), quinone compounds such as anthraquinone and naphthoquinone, and disulfide compounds such as diphenyl disulfide donato.
The amount of these added may be 0.05 to 5 parts by weight.

Note that when 5 parts by weight or more is used, the product generally becomes expensive.

The varnish thus obtained is an ultraviolet curable solvent-free varnish.

The varnish uses a light source that generates ultraviolet light, such as a low-pressure, medium-pressure, or high-pressure mercury lamp, a xenon lamp, or a germicidal lamp.

These light sources may be of normal shape and may be used as they are, or may be of other shape, such as a coiled light source.

The ultraviolet curable varnish obtained as described above may further contain additives for the purpose of modifying the properties of the cured varnish.

For example, since the prepolymer (4) used in the present invention has a hydroxyl group in its molecule, it is advisable to incorporate an incyanate compound into the varnish in consideration of its utilization.

Examples of incyanate compounds for this purpose include blocked isocyanates in which the incyanate group is blocked with phenol, cresol, etc. (for example, Coronate AP-Stafle, Millionate Ms, Desmodur CT-Staffle, Millionate ME, etc. manufactured by Nippon Polyurethane Industries). The varnish is preferably used because of its long pot life.

The compound may be added in an amount corresponding to the hydroxyl equivalent of prepolymer (1) as the upper limit.

That is, the amount to be blended may be determined by taking into consideration the characteristics of the cured product finally obtained and the control of varnish viscosity by blending the compound.

The cured repeat formed from the obtained varnish by ultraviolet irradiation is then heat-treated to separate the blocking agent of the blocked isocyanate compound, thereby forming new crosslinks such as urethane bonds and allornate bonds, and further forming the varnish. If it has an acid value, an amide bond or the like will be introduced, and the physical properties of the cured product will be improved or modified.

The figure is a cross-sectional view showing an example of an apparatus for manufacturing insulated wires using the ultraviolet curing varnish according to the present invention, in which numeral 1 denotes a wire that moves at a predetermined speed in the direction of the arrow by a drive means (not shown); 2 is an ultraviolet curing type varnish, 21 is a varnish tank containing this varnish 2, and 3 is the varnish tank 2.
Hζ is provided with a temperature control means for adjusting the viscosity of the varnish 2; 4 is a duct for collecting a slight odor of the varnish; 5 is a varnish attached by passing the wire 1 through the varnish tank 21; 6 is a film thickness adjusting means for controlling the thickness of the film 5; 1 is a chamber made of a material that transmits ultraviolet rays; 8 is an ultraviolet lamp for irradiating the film 5 with ultraviolet rays; 9 That ultraviolet light 8
10 is a lamp house for housing the ultraviolet lamp 8, and 41 is an inert gas such as argon, nitrogen gas, carbon dioxide gas, etc. in the chamber γ. 42 is an exhaust pipe for discharging the introduced inert gas.

With the above configuration, the moving strand 1 is guided to the varnish tank 21, and the film thickness adjusting means 6 normally
The varnish film 5 is then applied to a predetermined film thickness.

Next, when the coating 5 is irradiated with ultraviolet rays emitted from the ultraviolet lamp 8, the coating 5 is cured extremely quickly.

In this case, (:) Since the ultraviolet curable varnish according to the present invention is a solvent-free varnish with a resin solid content of 100%, problems caused by solvent volatilization can be solved at once, that is, resource saving can be achieved, as well as safety, health and pollution problems. Countermeasures will be eliminated, or it will become easier to formulate appropriate measures against them.

(11) Curing of charcoal-treated varnish is easily done by UV irradiation at room temperature without heating, so there is no need to warm up in a high-temperature (approximately 300 to 400°C) heating furnace as with conventional insulated wires. The workday can be started and ended by opening and closing the lighting switch of the ultraviolet lamp.

(jii) Since it is ultraviolet curing, production can be resumed immediately by simply replacing the lamp, and there is no need for maintenance, which requires a long period of time in a heating furnace as in conventional methods.

0V) Moreover, since it is a cold cure technology, it is possible to avoid strict control of the baking and drying process as in conventional methods, and the problem of defective products can be significantly reduced.

(V) Furthermore, since the high-temperature furnace as described above is no longer necessary, the working environment can be easily made more comfortable, for example, so that summer work, which used to be poor, becomes easier.

(The main equipment required for Vll varnish curing is a light source (ultraviolet ray generation source), so the cost of equipment can be based on the current method with a large hole or be cheaper than that.

(ViDl) In addition to the advantages described above, the ultraviolet curable varnish according to the present invention usually makes it possible to apply an insulating film by applying the varnish once and drying and curing it.

Since this is a cold cure system using a solvent-free varnish, it is possible to form a film with an excellent appearance because there are no pinholes even on thick walls, and it is possible to improve production with extremely high efficiency. can.

It has the advantage of having the following effects or ripple effects.

Here, the functions of the equipment of the chamber 1 and the temperature control means 3 will be explained in further detail in relation to the ultraviolet curable varnish according to the present invention.

That is, the varnish of the present invention is polymerized and cured by a radical reaction, and is subject to the curing inhibiting effect of oxygen.

Due to this curing inhibiting effect, a few microns of the very surface of the coating film remains uncured.

Therefore, in order to eliminate the curing hindering effect, it is necessary to use an air-drying type varnish or to remove the oxygen that exhibits the above-mentioned curing effect, but it is generally better to adopt the latter concept. This is convenient because it can cover a wide variety of varnishes.

As a measure for this purpose, it is preferable to equip the chamber 1 as described above.

As described above, the chamber 1 may be made of a material that transmits ultraviolet rays, such as glass, quartz, various types of transparent plastic films, and sheets of such plastics.

On the other hand, the temperature regulating means 3 attached to the varnish tank 21 is provided for the following purpose.

That is, the ultraviolet curable varnish according to the present invention is composed of an unsaturated prepolymer, a monomer, and a curing accelerator, as described above.

The conditions in which they are used, such as insulated wires, are harsh,
In particular, when the varnish is required to have excellent electrical, mechanical, heat resistance, and even chemical resistance, the composition of the varnish should be carefully studied.

This is because the ultraviolet curing varnish has a solid content of 100%.For example, if you change the formulation by increasing the amount of liquid varnish because the varnish has a high viscosity, you can use the varnish to form the varnish. The cured film has quite significant changes in physical properties.

Therefore, when the ultraviolet curable varnish used has a high viscosity and needs to be applied smoothly, it is necessary to use temperature control means to adjust the viscosity without changing the composition of the monomer, which is a reactive diluent, as described above. For example, an electric heater or a heating medium (such as silicone oil, hot water, etc.) as 3.
It is preferable to use a flexible pipe that circulates the water.

On the other hand, the viscosity of the ultraviolet curing varnish used is low at room temperature, and as mentioned above, it is difficult to form an insulating film with one varnish application, for example, due to the fact that the viscosity is too low. If there is a tendency for the varnish to become too small, the amount of varnish applied may be adjusted by operating a cooling means as the temperature adjusting means 3, such as passing cold water through the above-mentioned corrugated pipe, and adjusting the viscosity of the varnish used.

As explained in detail above, the ultraviolet curable varnish according to the present invention makes it possible to manufacture insulated wires extremely rationally and with high efficiency.

The insulating coated electric wire obtained as described above may be transferred to a winding process as a product, or it may be coated with multiple insulating coats to make the wire characteristics more unique, for example, the first coat In order to overcoat the first coating with a varnish that exhibits properties different from those shown in the first coating, the overcoated wire is introduced into a varnish bath containing the ultraviolet curing varnish again to form an overcoat. All you have to do is implement it.

In addition, the insulating film formed as described above is a polymer that exhibits a crosslinked structure with three-dimensionally developed molecular chains, and this crosslinked polymer is transformed from a liquid varnish into a solid state (hardening) very quickly by ultraviolet irradiation. There is a slight possibility that radicals or branched unreacted unsaturated groups exist in the polymer structure.

In order to re-react these, the cured film becomes a more stable cross-linked polymer, and furthermore, for the purpose of alleviating the strain that occurs in the cured film due to the instantaneous phase change, insulation is used. It is a good idea to consider adding a step of heating the coal type wire.

This objective can be accomplished extremely easily by using the ultraviolet curable varnish of the present invention.

That is, the heat treatment is performed on the cured film, and no components are volatilized during this process.

In addition, this heat treatment does not require large activation energy unlike the condensation reaction that is the curing and drying mechanism of varnish in conventional methods, so it can be performed at a temperature of approximately 60 to 200°C. The above purpose can be achieved through a very simple process.

The present invention will be explained in more detail below with reference to Examples.

Example 1 In the above formula, R1□ and R1□ are seasonal QC-CH=CH-CO
') - represents and/or.

75 parts of prepolymer shown, 5 parts of glycidyl methacrylate, 10 parts of hydroxyethyl methacrylate, 5 parts of diallyl phthalate, 5 parts of Coronate AP-Staffle
2 parts by weight of benzoin methyl ether and 0.5 parts by weight of dicumyl peroxide were homogeneously dissolved to obtain an ultraviolet curable solvent-free enamel varnish.

This varnish will gradually solidify if left at room temperature, but
It liquefies when heated to ~80°C.

The prepolymer was synthesized as follows.

Trimellitic anhydride 3
9.4 g (0.2 mol), hydrogenated diaminodiphenylmethane 21.0 g (0.1 mol) and 100 g of m-cresol as a solvent were added, and the temperature was gradually raised.

When the reaction is carried out at 100 to 130°C for about 2 hours, a yellow precipitate is formed in the flask due to the formation of a dicarboxylic acid imide compound.

When nitrogen gas is blown into the system while raising the reaction temperature, an azeotropic mixture of produced water and m-cresol comes out of the system.

Next, the yellow precipitate is filtered, washed with methanol, and dried to obtain a dicarboxylic acid imide compound.

The compound had an acid value of 200. Into the same flask as above, 33.4 g (0,0
6mol), ethylene glycol 62g (1mol)
When the water condenses under the boiling point of ethylene glycol and is taken out of the system in the form of an azeotrope with ethylene glycol, the contents become a homogeneous transparent liquid.

The temperature is maintained at 160 to 180° C. while blowing nitrogen gas strongly to remove a large amount of ethylene glycol from the system.

When no more ethylene glycol has been distilled out, 50 g m
- After adding the cresol, 5.9 g of maleic anhydride (0
, 06 mol), hexahydrophthalic anhydride 9.2 g
(0.06 mol) was added, and the reaction temperature was 100-130.
Esterification was carried out at ℃, and the reaction product was precipitated with methanol. When the acid value became 130 or less, glycidyl methacrylate loa, 0 & (0.12 mol) was gradually added, and hydroquinone 0 was added as a polymerization inhibitor. .01w
t% of the prepolymer with an acid value of 5 after about 2 hours.
A cresol solution was obtained, and methanol was added thereto to precipitate the viscous solid of the prepolymer.

Using the above enamel varnish, drawing was carried out under the same conditions as in Example 1, except that the varnish bath was heated to 65°C.

The obtained insulated wire had a good appearance.

This electric wire was then heat treated in a 180° C. furnace for 1 minute and 30 seconds.

The thus obtained electric wire had a coating thickness of 0.032 mm, had no pinholes or uneven thickness, exhibited single-diameter windability, and had a heat-resistant softening temperature of 330°C.

[Brief explanation of drawings]

The figure is a sectional view showing an example of an apparatus for manufacturing insulated wires using the ultraviolet curing varnish according to the present invention. In the figure, 1 is a bare wire, 2 is a varnish, 21 is a varnish tank, and 5
is a film, 7 is a chamber, and 8 is an ultraviolet lamp.

Claims (1)

[Claims] 1. General formula (wherein R1 is -H or -C) I3 represents a residue of a dibasic acid, R2 represents a residue of a polyesterimide polyol, and R3 represents a residue of a polyesterimide polyol. 50 to 95 parts by weight of a prepolymer containing 30 moles or more of a compound represented by
50 to 5 parts by weight of monomer having unsaturated groups and/or
Alternatively, an ultraviolet curable varnish containing 0 to 1 equivalent of blocked isocyanate based on the hydroxyl group of the prepolymer, 0.05 to 5 parts by weight of a photosensitizer, and a desired amount of a polymerization catalyst. 2. The ultraviolet curable varnish according to claim 1, wherein styrene is used as the monomer.