JPH0248930A - Method and apparatus for impregnating with varnish - Google Patents

Abstract

PURPOSE:To enhance the varnish impregnability in a sheet-like base material by a method wherein the air in the sheet-like base material is displaced by liquid low boiling point solvent and, by evaporating said low boiling point solvent, said base material is impregnated with heated pre-impregnating varnish and, after that, further with normal varnish and finally the amount of said varnish is controlled with squeeze rolls and the like. CONSTITUTION:Low boiling point solvent 8 is sprayed from a spray nozzle 13 against both sides of a sheet-like base material 1 so as to displace the air in the base material by said solvent 8. In succession, by bringing the base material 1 into contact with a revolving roll 21, which is dipped in pre-impregnating varnish 18, so as to impregnate said base material 1 with pre-impregnating varnish 18. At that time, since the pre- impregnating varnish 18 is in heated state, the low boiling point solvent is vaporized simultaneously with the above-mentioned impregnation. Further, the sheet-like base material is impregnated with varnish 28 during its passing through the varnish 28 in a varnish impregnating tank 4. After that, the amount of varnish impregnated is controlled by the controlling mechanism 5 of the amount of varnish impregnated. Thus, the sheet-like base material, which is evenly impregnated with varnish and has no air left within, is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sheet-like base material made of a fibrous material such as paper or cloth used for manufacturing laminates such as electrical insulating boards and decorative boards. The present invention relates to a method and apparatus for impregnating varnish.

[Conventional technology]

Generally, when impregnating a sheet-like base material made of a fibrous material with varnish, it is important that the varnish is impregnated into the inside of the fibers of the sheet-like base material and that the varnish amount distribution in each part is even and uniform. It is desirable to reduce the number of air bubbles remaining in the sheet-like base material as much as possible.

Conventional impregnation methods generally involve immersing a sheet-like substrate in a varnish.

However, with such an impregnation method, it is difficult to sufficiently and uniformly impregnate the inside of the sheet-like base material with varnish, and there is a problem that it takes a long time to impregnate the varnish. Moreover, it is difficult to sufficiently reduce the number of air bubbles remaining in the sheet-like base material. This problem becomes particularly noticeable when a high viscosity varnish is used.

Therefore, recently, as shown in FIG.
, a solvent or a dilute varnish containing a large amount of solvent 118
It is practiced to immerse the varnish in a normal varnish 128.

In this way, compared to the above-mentioned traditional method, it is possible to improve the impregnation of the varnish into the inside of the base material, to achieve uniform impregnation, and to reduce air bubbles.

[Problem to be solved by the invention]

However, even in this method, the sheet-like base material 101 is simply immersed in the diluted varnish 1189 and the normal varnish 128, so when a thick sheet-like base material or a sheet-like base material with high liquid flow resistance is used, or When a high viscosity varnish is used, there is inevitably a limit to its impregnating properties, and it has not been possible to improve the varnish impregnating properties and void-free effect of the sheet-like base material to a certain extent.

The present invention has been made in view of this point.

To provide a varnish impregnation method capable of efficiently and uniformly impregnating a sheet-like base material with varnish and significantly reducing air bubbles in the sheet-like base material, and a varnish impregnation device capable of suitably carrying out the method. The purpose is to

[Means to solve the problem]

The varnish impregnation method of the present invention, which solves this problem, includes a pretreatment step in which air in a sheet-like base material made of a fibrous material is replaced with a liquid low-boiling point solvent, and a sheet-like base material that has undergone this step is filled with air. A preliminary impregnation step in which the pre-impregnated varnish heated to a predetermined temperature is impregnated while evaporating the low boiling point solvent substituted with the solvent, and a varnish impregnation step in which the pre-impregnated sheet-like base material is impregnated with a normal varnish. , and a varnish impregnation amount adjustment step of adjusting the amount of varnish impregnated into the sheet-like base material using a squeeze roll or the like.

Depending on the properties of the sheet-like base material and the varnish with which it is impregnated, the preliminary impregnation step can be omitted.

In the pretreatment step, it is preferable that the sheet-like substrate is passed through a vapor atmosphere of a low boiling point solvent. In this way, the solvent vapor condenses on the substrate surface and
The liquefied solvent will replace the air in the sheet-like substrate. Of course, the low boiling point solvent may be sprayed onto both sides of the sheet-like base material.

Furthermore, in the pretreatment step, the sheet-like base material may be immersed in a liquid low-boiling point solvent under a reduced pressure atmosphere, or the sheet-like base material may be immersed in a liquid low-boiling point solvent and the low-boiling point solvent Ultrasonic waves may be applied therein. It is preferable to use these methods in combination.

Furthermore, in the pre-impregnation step, it is preferable to evaporate the low boiling point solvent from one side of the sheet-like base material while impregnating the varnish for pre-impregnation from the other side of the sheet-like base material.

On the other hand, the varnish impregnation apparatus of the present invention for carrying out such a method is configured such that a sheet-like base material made of a fibrous material passes sequentially through a pretreatment tank, a preliminary impregnation tank, and a varnish impregnation tank,
The pre-treatment tank is equipped with an air displacement mechanism that replaces the air in the sheet-like base material with a liquid low boiling point solvent, and the pre-impregnation tank is
A pre-impregnation mechanism for impregnating the pre-impregnating varnish while evaporating the low boiling point solvent in the sheet-like base material, and a varnish heating mechanism for heating the pre-impregnating varnish to a predetermined temperature are provided. In addition to providing a varnish impregnation mechanism that impregnates the material with ordinary varnish, a varnish impregnation mechanism is installed near the varnish impregnation tank.
A varnish impregnation amount adjustment mechanism is provided to adjust the amount of varnish impregnated into the sheet-like base material.

When the pre-impregnation step is omitted as described above, the pre-impregnation tank is not provided and the sheet-like substrate is guided from the pre-treatment tank to the varnish impregnation tank.

[Effect]

In the pretreatment process, the air in the fibers of the sheet-like base material is replaced with a liquid low-boiling point solvent, but since the sheet-like base material is opened by wetting with the low-boiling point solvent, the liquid low-boiling point solvent is Coupled with the low surface tension, the low boiling point solvent sufficiently penetrates into the fibers of the sheet-like base material, and most of the air within the fibers is expelled.

By the way, when a sheet-like base material is passed through a vapor atmosphere of a low-boiling point solvent, the solvent vapor condenses and liquefies on the surface of the base material, and the liquefied solvent replaces the air in the sheet-like base material. In addition, when the sheet-like base material is immersed in a low-boiling point solvent under reduced pressure conditions, or when ultrasonic waves are applied to the solvent in which the sheet-like base material is immersed, the defoaming effect due to the reduced pressure or the ultrasonic wave The effect is a better displacement of air and low-boiling solvent.

In the preliminary impregnation process, as described above, the air inside the fibers is replaced with a liquid low-boiling solvent, and the low-boiling solvent is evaporated from one base material surface while the other base material surface is evaporated. Let it be impregnated with pre-impregnation varnish.

In this step, since the pre-impregnation varnish is heated to have a low viscosity, it is easily replaced by the low boiling point solvent in the sheet-like base material. Moreover, the suction force accompanying the evaporation of the low boiling point solvent promotes the penetration of the pre-impregnating varnish into the base material, so the sheet-like base material is sufficiently impregnated with the pre-impregnating varnish to the inside of its fibers. That will happen. By impregnating with such pre-impregnating varnish, air in the sheet-like substrate is further removed.

In the varnish impregnation process, the sheet-like base material impregnated with the pre-impregnation varnish as described above is further impregnated with a normal varnish, but since there is almost no air remaining in the sheet-like base material, the varnish This results in sufficient impregnation of the fibers into the interior of the fibers.

In addition, when the pre-impregnation step is omitted, the low boiling point solvent in the sheet-like base material is replaced with a normal varnish, but in this case as well, the low-boiling point solvent must be easily replaced with the varnish, and the sheet-like base material must be easily replaced with the varnish. Since there is almost no air in the material that prevents varnish from penetrating, the sheet-like base material can be impregnated with varnish well.

In the varnish impregnation amount adjustment step, excess varnish is removed from the sheet-like base material using a squeeze roll or a squeeze bar, and the varnish amount is adjusted evenly and uniformly. Such adjustment is
As described above, this is effectively carried out by sufficiently impregnating the inside of the base material with the varnish.

〔Example〕

Hereinafter, the structure of the present invention will be specifically explained based on each embodiment shown in FIGS. 1 to 6.

FIG. 1 shows a first embodiment. In the varnish impregnation apparatus shown in FIG. , 4 is a varnish impregnation tank, and 5 is a varnish impregnation amount adjustment mechanism.

The sheet-like base material 1 is passed from a base material supply source 1' such as a paper roll, through guide rolls 9, 11, 30, etc., to a pretreatment tank 2, a preliminary impregnation tank 3. Varnish impregnation tank4. It is made to pass through the varnish impregnated amount adjustment mechanism 5 one after another.

Note that the sheet-like base material 1 may be a woven fabric or a nonwoven fabric made of synthetic, natural, organic, or inorganic fibers, such as paper.

Glass fiber cloth, glass fiber nonwoven fabric, carbon fiber cloth, carbon fiber nonwoven fabric, aramid fiber cloth, aramid fiber nonwoven fabric, etc. are used.

The pretreatment tank 2 is configured as a closed container with a convex cross section and whose upper part is covered with a box-shaped solvent cover 6.

The pretreatment tank 2 is formed with an inlet slit 7a for introducing the sheet-like substrate 1 into the tank 2, and an exit slit 7b for leading the sheet-like substrate 1 out of the tank 2.

In the pretreatment tank 2, first and third guide rolls 10a and 10c are placed near the bottom of the tank, and a solvent cover 6 is installed.
A second guide roll 10b is disposed above each of the two guide rolls 10b to allow the sheet-like base material 1 to pass from the inlet slit 7a to the outlet slit 7b in a substantially W-shape.

A solvent reservoir 8 is located below the substrate passage area 2a of the pretreatment tank 2.
' is formed, and a predetermined amount of liquid low boiling point solvent 8 is stored. The solvent 8 is generally a single or a mixture of two or more appropriate low-boiling point organic compounds depending on the properties of the base material 1, etc.; It is preferable to select one whose temperature exceeds the base material temperature (usually 10 to 30'C) and not more than 80'C.

If the boiling point is below the substrate temperature, there is a risk that the solvent will evaporate during or immediately after the air replacement, and if the boiling point exceeds 80°C, it will be difficult to evaporate the solvent in the process after the air replacement. be. Organic compounds that satisfy these conditions include:
For example, vinylidene dichloride (boiling point 31.7°C), methyl formate (boiling point 32°C), ethyl ether (boiling point 34°C).
5°C), isopropyl chloride (boiling point 34.8°C), propylene oxide (boiling point 35°C) + n-pentane (boiling point 36.8°C).
1°C), ethyl bromide (boiling point 38.4°C), methylene dichloride (boiling point 39.8°C), propyl chloride (boiling point 46°6
°C), 1.1.2-trifluorotrichloride ethane (boiling point 47.
5°C), acetone (boiling point 56.3°C), methyl acetate (
(boiling point 56.3°C), ethylidene dichloride (boiling point 57.3°C)
°C), chloroform (boiling point 61°2°C), methanol (
Boiling point 64. '7°C), tetrahydrofuran (boiling point 65
．． 6°C), isopropyl ether (boiling point 68.4°C)
n-hexane (boiling point 68.7°C), 1.1.1-trichlorethane (boiling point 73.9°C), ethyl acetate (boiling point 76.8°C)
℃).

Ethanol (boiling point 78.3℃), methyl ethyl ketone (
boiling point 79.5°C).

Note that the slits 7a and 7b are designed to have the minimum necessary size to allow the sheet-like base material 1 to pass through.
It is desirable to prevent solvent evaporation loss from b. Furthermore, in the pretreatment tank 2, the slit 7a
, 7b and above the solvent cover 6, it is desirable to provide a solvent recovery means such as a solvent condensing coil (not shown).

Further, the pretreatment tank 2 is provided with an air displacement mechanism 12 that replaces the air in the sheet-like base material 1 with a low boiling point solvent 8. This air displacement mechanism 12 is constructed by disposing a plurality of spray nozzles 13 within the solvent cover 6, and connecting the spray nozzles 13 to a solvent supply pipe 14 led from the solvent reservoir 8'. By operating a pump 15 installed in this pipe line 14, the low boiling point solvent 8 is sprayed from spray nozzles 13 onto both sides of the base material 1 portion in the base material passage area 2a. .

In addition, in the vicinity of the outlet loss slit 7b in the pretreatment tank 2,
A pair of squeeze rolls (or squeeze bars) 16° 16 are provided for squeezing the sheet-like base material 1 that has passed through the guide roll 10c to adjust the amount of solvent impregnated therein.

The pre-impregnation tank 3 is configured in a box shape with an open top surface, and stores a predetermined amount of varnish 18 for pre-impregnation. In this pre-impregnation tank 3, a varnish 1 for pre-impregnation is applied to a sheet-like base material 1.
A preliminary impregnation mechanism 19 for impregnating the varnish 8 and a varnish heating mechanism 20 for heating the varnish 18 are provided.

That is, the pre-impregnation mechanism 19 includes a rotary roll 21 whose outer peripheral lower surface is dipped in the pre-impregnated varnish 18, and a pair of pressers that press and hold the sheet-like base material 1 against the outer peripheral upper surface of the rotary roll 21 in a rolling contact manner. The zero rotation roll 21 comprising the rolls 22a and 22b is rotated in accordance with the running speed of the sheet-like base material 1, and is heated to a predetermined temperature by an appropriate heating means (not shown). has been done. Presser roll 22a
.

By changing the position of 22b, the contact area and contact pressure with respect to the sheet-like base material 1 can be adjusted, and the amount of varnish impregnated can be appropriately controlled according to the types of the sheet-like base material 1 and the varnish 18.

Further, the varnish heating mechanism 20 includes a jacket 23 provided in the preliminary impregnation tank 3, a heat medium circulation path 24 connected to the jacket 23, a warmer 25 and a circulation pump 26 interposed therein, The preliminary impregnation varnish 18 is heated to a predetermined temperature by circulating and supplying an appropriate heat medium such as heated water to the jacket 23.

It is designed to keep you warm.

By the way, the viscosity of the varnish 18 can be lowered by heating, but if the temperature is increased more than necessary, the solvent blended in the varnish 18 will easily evaporate, and there is a risk that the viscosity will increase. Therefore, it is preferable to heat the pre-impregnating varnish 18 to about 40°C.

In addition, as the pre-impregnation varnish 18, thermosetting resin varnish is generally used, but in addition, thermoplastic resin,
Varnishes made of natural resins, solvent-free liquid synthetic resins, liquid natural resins, etc. can also be used.

The varnish impregnation tank 4 is configured in a box shape with an open top.
This varnish impregnation tank 4 is provided with a varnish impregnation mechanism 27. That is, a predetermined amount of varnish 28 is placed in the varnish impregnation tank 4.
A pair of guide rolls 29a and 29b are arranged in the storage area so that the sheet-like base material 1 that has passed through the guide rolls 30 is immersed in the varnish 28.

By the way, as the varnish 28, the pre-impregnation varnish 18 is used.
It may be the same as or different from , and is appropriately selected as necessary. An example of its composition is shown in the table below.

<Varnish composition> Furthermore, above the varnish impregnation tank 4, a sheet-like base material 1
A varnish impregnation amount adjustment mechanism 5 is provided to adjust the varnish impregnation amount. This mechanism 5 consists of a pair of squeeze rolls or squeeze pars 31.31 and a guide roll 29.
By squeezing the sheet-like base material 1 that has passed step b, the amount of varnish impregnated is adjusted to a uniform and appropriate amount.

Next, the method of the present invention will be specifically explained using the varnish impregnation apparatus configured as described above.

[Pre-treatment process]

When the sheet-like base material 1 is brought into the pretreatment tank 2 from the base material supply source 1', a low-boiling point solvent 8 is sprayed onto both sides of the sheet-like base material 1 from the spray nozzles 13, and the inside of the sheet-like base material 1 is The air will be replaced with a low boiling point solvent 8. That is, since the surface tension of the low boiling point solvent 8 is small and the sheet-like base material 1 is opened by wetting with the low boiling point solvent 8,
The low boiling point solvent 8 sufficiently penetrates into the fibers of the sheet-like base material 1, and most of the air within the fibers is expelled. By the way, depending on the spraying of the low boiling point solvent 8,
In addition to replacing the air in the sheet-like base material 1 with the low-boiling point solvent 8, the base material layer contained in the sheet-like base material 1, attached moisture, etc. are also removed, and the quality as a varnish impregnating material is further improved. I will do it.

The sheet-like base material 1 impregnated with the low boiling point solvent 8 has the amount of solvent impregnated uniformly adjusted by the squeeze rolls 16, 16, and then passes through the outlet slit 7b to the pre-impregnation tank 3.
brought to you. Note that the amount of solvent contained in the sheet-like base material 1 is preferably 50% by weight or less 7 [Pre-impregnation step] The sheet-like base material 1 brought into the pre-impregnation tank 3 is It is pressed against the upper surface of the outer periphery of the rotating roll 21. At this time, the lower surface of the outer circumference of the rotating roll 21 is immersed in the pre-impregnation varnish 18, and as the single-turn roll 21 rotates, the pre-impregnating varnish 18 adheres to the outer circumferential surface of the rotating roll 21 and forms a sheet-like substrate. The sheet-like substrate 1 is impregnated with the pre-impregnating varnish 18 since it is brought into contact with the material 1 . Moreover, since the rotating roll 21 and the preliminary impregnation varnish 18 are heated, the low boiling point solvent 8 impregnated into the sheet-like base material 1 is evaporated at the same time as the impregnation. That is, in the portion of the base material 1 that is in contact with the rotating roll 21, the low boiling point solvent 8 is evaporated from the upper surface thereof, and the pre-impregnating varnish 18 is impregnated from the lower surface thereof. Therefore, the varnish 18 for pre-impregnation is heated to have a low viscosity, and has high permeability into the sheet-like base material 1, and the suction force accompanying the evaporation of the low-boiling solvent 8 makes the varnish 18 for pre-impregnation low. Since the penetration of the pre-impregnating varnish 18 is promoted, the pre-impregnating varnish 18 is sufficiently impregnated into the fiber structure of the sheet-like base material 1. Note that, by impregnating with the pre-impregnating varnish 18, air within the sheet-like base material 1 is further removed.

[Varnish Impregnation Step] The sheet-like base material 1 pre-impregnated with the varnish 18 for pre-impregnation in this way is completely impregnated with the varnish 28 while passing through the varnish 28 in the varnish impregnation tank 4 . That is, in the pre-impregnation step, since the pre-impregnation varnish 18 is heated, it is difficult to maintain a constant resin content due to evaporation and replenishment of the blended solvent. Therefore, the resin content in No. 1 can be kept constant.

By the way, generally, unless the sheet-like base material 1 is heated in advance, it is at a lower temperature than the varnish 28. Therefore, the varnish temperature in the varnish impregnation tank 4 decreases by dipping the sheet-like base material 1, and the viscosity of the varnish 28 decreases. There is a risk that the impregnating property will increase and the impregnating property will deteriorate. However, since the sheet-like base material 1 is heated during preliminary impregnation as described above, such a risk does not occur.

[Varnish impregnation amount adjustment process]

The sheet-like base material 1 that has passed through the varnish impregnation tank 4 has its varnish impregnated amount adjusted uniformly by a varnish impregnated amount adjustment mechanism 5, that is, a squeeze roll or squeeze par 31.31.

Therefore, it is possible to obtain a sheet-like base material 1 in which the varnish 28 is sufficiently and uniformly impregnated and in which almost no air remains in the fiber structure.

The varnish impregnation method and its apparatus of the present invention are not limited to the above embodiments, but can also be configured as follows.

That is, FIG. 2 shows the second embodiment. In the varnish impregnation apparatus of this embodiment, unlike the first embodiment, the preliminary impregnation tank 3 is not provided, and the sheet-like material that has passed through the pretreatment tank 2 is It is configured to lead the base material 1 to the varnish impregnation tank 4 without pre-impregnating it.

The structure is the same as that of the first embodiment except that the pre-impregnating tank 3 and the pre-impregnating mechanism 19 are eliminated, so the same components are given the same reference numerals in FIG. 2 and the details thereof will be omitted.

In this example, the sheet-like base material 1 containing the low-boiling point solvent 8 is immersed in the varnish 28. At this time, since the air in the sheet-like base material 1 is replaced with the solvent, when the varnish viscosity is high, Also, since the contained solvent 8 can be easily replaced with the varnish 28, the same impregnation effect as in the case where a preliminary impregnation step is added can be achieved. However, since the solvent 8 contained in the sheet-like base material 1 may mix into the varnish 28 in the varnish impregnation tank 4, the low boiling point solvent 8 used in the pretreatment step may be methyl ethyl ketone or the like shown in the table above. It is necessary to use a solvent of the same quality as the mixed solvent of varnish 28.

Furthermore, in each of the above embodiments, the air in the sheet-like base material 1 was replaced with the low-boiling-point solvent 8 by spraying the liquid low-boiling point solvent 8 onto the sheet-like base material 1. can also be done as follows.

That is, in the third embodiment shown in FIG. 3, the air displacement mechanism 12 includes a solvent heating mechanism 32 that heats the low boiling point solvent 8 to a temperature higher than the substrate temperature and evaporates it, and 2
A is maintained in a vapor atmosphere of a low boiling point solvent 8. Therefore, in the pretreatment step of this embodiment, while the sheet-like substrate 1 whose temperature is below the vapor temperature of the low boiling point solvent 8 passes through the solvent vapor atmosphere, the solvent vapor condenses on the substrate surface. , the condensed solvent replaces the air in the sheet-like substrate 1.

In the first to third embodiments, although not shown, there is an air exhaust means for discharging the air substituted with the low boiling point solvent 8 to the outside of the pretreatment tank 2, and an air exhaust means for recovering the solvent in the discharged air. Solvent recovery means are provided for this purpose. For example, an air exhaust port is formed in the earthen wall of the solvent cover 6, and a vacuum pump, a condenser, etc. are installed in the air exhaust pipe line connected to the air exhaust port.

Furthermore, in the fourth embodiment shown in FIG.
However, it is equipped with an ultrasonic oscillation mechanism 33 such as an ultrasonic oscillation amount that oscillates ultrasonic waves in the low boiling point solvent 8, and a pressure reduction mechanism 34 that reduces the pressure in the liquid seal space 6a in the solvent cover 6.

The decompression mechanism 34 includes a suction port 6b formed in the earthen wall of the solvent cover 6, and a condenser 37 and a gas-liquid separator 38 interposed in a suction pipe 36 leading from the suction port 6b to the vacuum pump 35. Furthermore, a pump 40 and a check valve 41 are interposed in a recovery pipe 39 leading from the gas-liquid separator 38 to the solvent storage section 8'.

Incidentally, an appropriate cooling means 48 is attached to the solvent storage section 8'.

In the pretreatment step of this embodiment, when the sheet-like base material 1 is immersed in a low-boiling point solvent 8 treated with ultrasonic waves, the air within the fibers is heated to a low boiling point by the ultrasonic action. It is forcibly replaced with solvent 8. At this time, the liquid seal space 6a is depressurized by the vacuum pump 35, so that the liquid level in the solvent storage part 8' rises, the time for receiving the ultrasonic action becomes longer, and the defoaming effect due to the depressurization is exerted. Because of that,
The above substitution is performed more effectively. In addition, the suction pipe 3
The solvent in the air discharged from 6 is separated by a condenser 37 and a gas-liquid separator 38, and is recovered from a recovery pipe 39 to a solvent reservoir 8'. Note that it is best to use the ultrasonic oscillation mechanism 33 and the pressure reduction mechanism 34 together, but the sheet-like base material 1
Depending on the two types of properties, only one of them may be used.

By the way, which of the air replacement steps in the first to fourth embodiments is adopted depends on the properties of the sheet-like base material 1.

This can be determined depending on the type, etc., but in any case, a coil for solvent condensation (not shown) is provided in the vicinity of the slits 7a and 7b in the pretreatment tank 2 and in the upper part of the solvent cover 6. Preferably, the solvent is collected.

Further, in each of the above embodiments, the sheet-like base material 1 was impregnated with the pre-impregnating varnish 18 by the so-called kiss coating method using the rotating roll 21, but such pre-impregnating can be carried out by the following dipping method. , the spraying may be done by law.

That is, in the fifth example shown in FIG.
- A base material heating mechanism, for example, a heater 43 such as a radiant plate is disposed near the top surface.

In the preliminary impregnation step of this embodiment, the impregnating solvent is evaporated from the upper surface of the sheet-like base material 1 while the sheet-like base material 1 is
Pre-impregnating varnish 18 is impregnated from the bottom surface of the container.

Further, in the sixth embodiment shown in FIG. 6, the pre-impregnation mechanism 19
However, a plurality of spray nozzles 45 are arranged in the vicinity of and immediately below the first part of the base material between the guide rolls 44a and 44b, and the varnish introduced from the reservoir of the pre-impregnating varnish 18 is applied to the nozzles 45. By connecting a supply pipe line 46 and operating a pump 47 interposed in this pipe line 46, the pre-impregnating varnish 18 is sprayed onto the lower surface of the sheet-like base material 1 from nozzles 45... It is composed of In addition,
A substrate heating mechanism 43 is disposed near the upper surface of the substrate 1 portion, as in the above embodiment.

Further, the pre-impregnation tank 3 may have a closed container structure like the pre-treatment tank 2, and may be provided with a means for recovering the solvent substituted for the pre-impregnation varnish 18.

Furthermore, in each of the above embodiments, impregnation with the varnish 28 was performed by a dipping method, but spraying may be performed by a method such as a method or a coating method.

〔Effect of the invention〕

As can be easily understood from the above explanation, according to the present invention, the air in the sheet-like base material is replaced with a liquid low-boiling point solvent, and then the sheet-like base material is impregnated with varnish, or In this method, the varnish is impregnated after replacing the contained solvent with a pre-impregnated varnish whose viscosity has been lowered by heating, and the amount of varnish impregnated is finally adjusted. Regardless of the properties of the varnish to be impregnated with.

The sheet-like base material can be impregnated with varnish evenly and in a sufficiently short period of time, and the air bubbles in the sheet-like base material can be reduced as much as possible. This effect is significant when impregnating high viscosity varnishes.

Therefore, the use of sheet-like substrates impregnated with varnish according to the invention can significantly improve the quality of final products such as composite materials, such as electrical insulation boards, decorative boards, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a first embodiment of the varnish impregnation device according to the present invention, FIG. 2 is a schematic cross-sectional view of the main part of the device showing the second embodiment, and FIG. FIG. 4 is a schematic sectional view of the main part of the device showing the fourth embodiment; FIG. 5 is a schematic sectional view of the main part of the device showing the fifth embodiment. FIG. 6 is a schematic sectional view of an apparatus showing a sixth embodiment, and FIG. 7 is a schematic sectional view showing a conventional technique.
...solvent heating mechanism, 33...ultrasonic oscillation mechanism, 34
... Pressure reduction mechanism, 43... Base material heating mechanism. 1... Sheet-like base material, 2... Pretreatment tank, 2a...
Base material passage area, 3... preliminary impregnation tank, 4... varnish impregnation tank. 5... Varnish impregnation amount adjustment mechanism, 7a... Inlet slit. 7b...Exit slit, 8...Solvent, 9, 10a,
10b, 10c, 11, 29a, 29b, 30, 42
a, 42 b, 44 a, 44 b”・
Guide roll, 12... Air displacement mechanism, 13... Spray nozzle, 18... Pre-impregnation varnish, 19...
・Preliminary impregnation mechanism, 20... Varnish heating mechanism, 21...
- Rotating roll, 22a.

Claims (8)

[Claims] (1) A pretreatment step in which the air in the sheet-like base material made of fibrous material is replaced with a liquid low-boiling point solvent; At the same time, there is a pre-impregnation step in which the heated pre-impregnation varnish is impregnated, a varnish impregnation step in which the sheet-like base material is further impregnated with a normal varnish, and the amount of varnish impregnated into the sheet-like base material is transferred to a squeeze roll or the like. A varnish impregnation method characterized by comprising: a varnish impregnation amount adjustment step. (2) A pretreatment step in which air in a sheet-like base material made of fibrous material is replaced with a liquid low-boiling point solvent, a varnish impregnation step in which this sheet-like base material is impregnated with varnish, and a varnish impregnation step in which the sheet-like base material is impregnated. A method for impregnating varnish, comprising: adjusting the amount of varnish impregnated using a squeeze roll or the like. (3) The varnish impregnation method according to claim 1 or 2, wherein in the pretreatment step, the sheet-like substrate is passed through a vapor atmosphere of a low boiling point solvent. (4) The varnish impregnation method according to claim 1 or 2, characterized in that in the pretreatment step, the sheet-like substrate is immersed in a liquid low boiling point solvent under reduced pressure conditions. (5) In the pretreatment step, the sheet-like base material is immersed in a liquid low boiling point solvent and ultrasonic waves are applied to the low boiling point solvent. The varnish impregnation method according to claim 4. (6) In the pre-impregnation step, the low boiling point solvent is evaporated from one side of the sheet-like base material, while the pre-impregnation varnish is impregnated from the other side of the sheet-like base material, The varnish impregnation method according to claim 1, claim 3, claim 4, or claim 5. (7) A varnish impregnation apparatus configured such that a sheet-like base material made of a fibrous material passes through a pre-treatment tank, a pre-impregnation tank, and a varnish-impregnation tank in sequence, the pre-treatment tank having a An air displacement mechanism for replacing air with a liquid low boiling point solvent is provided, and a pre-impregnation mechanism is provided in the pre-impregnation tank for evaporating the low boiling point solvent in the sheet-like base material and impregnating the sheet-like base material with a varnish for pre-impregnation; A varnish heating mechanism for heating the varnish for preliminary impregnation is provided, a varnish impregnation mechanism for impregnating the sheet-like substrate with normal varnish is provided in the varnish impregnation tank, and a sheet-like substrate is heated near the varnish impregnation tank. A varnish impregnating device characterized in that a varnish impregnation amount adjustment mechanism is provided to adjust the amount of varnish impregnated into the varnish. (8) A varnish impregnation device configured such that a sheet-like base material made of a fibrous material passes through a pre-treatment tank and a varnish-impregnating tank in sequence, wherein the air in the sheet-like base material is transferred to the pre-treatment tank in liquid form. An air displacement mechanism is provided to replace the low-boiling point solvent, and a varnish impregnation mechanism is provided in the varnish impregnation tank to impregnate the sheet-like base material with ordinary varnish.
A varnish impregnation device characterized by being provided with a varnish impregnation amount adjustment mechanism that adjusts the amount of varnish impregnated into a sheet-like base material.