JPH02208009A - Impregnating process with varnish and its device - Google Patents

Abstract

PURPOSE:To improve remarkably the impregnation property with varnish and the voidless effect in a face by a method in which the closely sealing thermal siphon area connected to both low viscous liquid-storing area and varnish-storing area in the state of said areas being liquid-sealed with the liquid surface, is provided between said both areas, and the sheetlike base composed of fiber material is successively advanced to these areas. CONSTITUTION:A base 1 is brought into a low viscous liquid-storing tank 2 from a base-feeding source, and is dipped in low viscous liquid 12, and then the air therein is displaced by the low viscous liquid 12. When the base 1 reaches its liquid surface 2', the low viscous liquid 12 permeates the fiber bundle constituting the base 1, and the all air in the fiber bundle is displaced by said liquid 12 and is discharged, while the base 1 passes an area 2'. The base 1 is brought in a thermal siphon room 4 from the inlet 4a of the base, and contains only saturated vapor of the heated base liquid 12. When the saturated vapor of the low viscous liquid contained in the base 1 enters a varnish-storing area 3', it becomes very little saturated liquid of low viscous liquid, and is dispersed in the varnish 13, whereby the impregnation achieved with the varnish 13 is fully and uniformly carried out.

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 water with varnish.

[Conventional technology]

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

In conventional impregnation methods, the substrate is generally pre-impregnated with a regular varnish for pre-impregnation, and then led to a varnish tank via a timing roll to be impregnated with a regular varnish. be.

However, with this impregnation method, it is difficult to uniformly and sufficiently impregnate the inside of the base material with the varnish.
There was a problem in that it took a long time to impregnate the varnish. Furthermore, it is difficult to sufficiently reduce the number of bubbles remaining in the base material.

This problem becomes particularly noticeable when a high viscosity varnish is used.

Therefore, recently, in place of the above-mentioned ordinary varnish for pre-impregnation, a dilute varnish containing a large amount of solvent or a solvent (hereinafter referred to as "
A pre-impregnating tank storing a pre-impregnating liquid (referred to as "pre-impregnating liquid") and a main impregnating tank storing a normal varnish are placed side by side, and the base material is moved to the pre-impregnating tank by guide rolls.

This impregnation tank is passed through in sequence.

According to this impregnation method, while the substrate is passed through the pre-impregnating liquid, the air in the substrate is replaced with the pre-impregnating liquid and removed, so that the pre-impregnating liquid impregnated in the substrate is removed. When the liquid is introduced into the varnish while being evaporated, the varnish can be impregnated efficiently and bubbles can be reduced.

[Problem to be solved by the invention]

However, in the transition stage from the pre-impregnating liquid to the varnish, the base material is exposed to air and is compressed by the guide rolls between the two tanks, so air in the base material is not removed sufficiently and the varnish is Impregnating properties and voidless effects cannot be expected.

In other words, when the base material reaches the guide roll, contact surface pressure acts on the fiber bundles constituting the base material, causing the fiber bundles to open, and the reserve held by the capillary force within the fiber bundles to open. The liquid phase of the impregnating liquid is destroyed. The fiber bundle is decompressed when it passes through this guide roll, but the opened fiber bundle is reformed by this decompressing action.

As described above, since the destruction of the impregnating liquid phase in the fiber bundle and the reformation of the opened fiber bundle take place in the air, air is present in the base material during the transition stage from the pre-impregnating liquid to the varnish. There is a risk of re-invasion.

The present invention has been made in view of the above, and an object of the present invention is to provide a varnish impregnation method that can significantly improve the varnish impregnation properties and void-free effect in a base material, and a varnish impregnation apparatus that can suitably carry out the method. That is.

[Means to solve problems]

The varnish impregnation method of the present invention solves this problem by providing a liquid seal between the low viscosity liquid storage area where a low viscosity liquid such as a solvent can be stored and the varnish storage area where the varnish can be stored. A sealed thermosyphon region is provided that communicates with the thermosyphon in a closed state, so that the sheet-like base material made of fibrous material passes through the low-viscosity liquid storage region, the thermosyphon region, and the varnish storage region in sequence. In the siphon area, the base material is heated to evaporate the low viscosity liquid impregnated into it, and the low viscosity liquid vapor generated in the area is condensed and liquefied, and the condensed and liquefied low viscosity liquid is converted into a low viscosity liquid. The low viscosity liquid is collected to the storage area side, and the low viscosity liquid is further heated and evaporated in the communication area between the thermosiphon area and the low viscosity liquid storage area, and the amount of evaporation is controlled according to the fluctuation of the liquid sealing surface in the communication area. This is what I did.

On the other hand, the varnish impregnation apparatus of the present invention for carrying out such a method includes a low viscosity liquid storage tank storing a low viscosity liquid such as a solvent, a varnish storage tank storing varnish, and a liquid level below the liquid level in each storage tank. A closed thermosyphon chamber with a cylindrical base material inlet opening and a base material outlet vertically installed; A base material running guide mechanism that guides the base material through the thermosyphon chamber and further leads it from the base material outlet to the varnish storage tank, and a base material heating system that heats the base material in the thermosyphon chamber and evaporates the low-viscosity liquid impregnated into the base material. a cooling mechanism that condenses and liquefies the low-viscosity liquid vapor in the thermosiphon chamber; a condensate recovery mechanism that recovers the low-viscosity liquid condensed and liquefied by the cooling mechanism into the low-viscosity liquid storage tank; A low viscosity liquid configured such that a low viscosity liquid heating surface extending vertically is disposed in the low viscosity liquid reservoir so that the amount of heating and evaporation of the low viscosity liquid changes as the liquid level in the low viscosity liquid reservoir changes. A heating mechanism is provided.

[Effect]

While the substrate passes through the low viscosity liquid reservoir, the air in the substrate is replaced with the low viscosity liquid and removed.

The base material impregnated with the low viscosity liquid is then brought into the thermosyphon chamber from the base material inlet and heated by the base material heating mechanism. By heating the base material, the low viscosity liquid impregnated therein is evaporated and separated.

At this time, the vapor pressure in the thermosiphon chamber is maintained within a certain range as long as the amount of evaporation of the low viscosity liquid by the base material heating mechanism and the low viscosity liquid heating mechanism and the amount of condensation by the cooling mechanism are in equilibrium. Changes in varnish impregnation conditions such as base material running speed,
If it fluctuates, the balance between the amount of evaporation and the amount of condensation will be disrupted, and the steam pressure in the thermosyphon chamber will fluctuate, which may result in the above-mentioned effects not being performed satisfactorily.

However, when the steam pressure in the thermosyphon chamber fluctuates, the liquid level in the low-viscosity liquid reservoir (and the liquid level in the varnish reservoir) also fluctuates, and the amount of evaporation by the low-viscosity liquid heating mechanism changes accordingly. It will be automatically controlled. In other words, when the vapor pressure decreases and the liquid level in the low-viscosity liquid reservoir rises, the amount of immersion of the low-viscosity liquid heating surface in the low-viscosity liquid reservoir, that is, the contact area between the low-viscosity liquid and the low-viscosity liquid heating surface increases. As a result, the amount of evaporation caused by the low-viscosity liquid heating mechanism increases by an amount corresponding to the amount of decrease in steam pressure, thereby preventing fluctuations in steam pressure in the thermosyphon chamber. Conversely, when the vapor pressure increases, the liquid level in the low-viscosity liquid reservoir falls, the contact area between the low-viscosity liquid and the low-viscosity liquid heating surface decreases, and the amount of evaporation due to the low-viscosity liquid heating mechanism decreases. decreases and prevents the steam pressure from increasing.

In this way, the steam pressure in the thermosiphon chamber is self-controlled and always maintained within a certain range without the need for a pressure control device or the like. Furthermore, in cases such as when the base material travel is stopped due to an operational stop or when there is a change or fluctuation in the base material travel speed, the amount of condensation caused by the cooling mechanism may significantly exceed the amount of evaporation caused by heating the base material. In this case, there is a risk that the thermosyphon chamber becomes vacuum or negative pressure, causing problems such as low viscosity liquid and varnish being sucked up into the thermosyphon chamber from the substrate inlet and substrate outlet. Such inconvenience does not occur at all.

Further, since the low viscosity liquid condensed by the cooling mechanism is collected into the low viscosity liquid storage tank, the loss of the low viscosity liquid and the intrusion into the varnish storage tank are prevented as much as possible.

Therefore, in the thermosyphon region, the substrate will function well as a thermosiphon wick, and the substrate will be brought from the thermosyphon region to the varnish storage region in a state containing only saturated vapor of a low viscosity liquid. It turns out.

That is, no air enters the substrate during the transition stage from the low viscosity liquid reservoir region to the varnish reservoir region, resulting in an air-free substrate in the varnish region.

As a result, when the substrate is brought into the varnish reservoir area, the substrate is better impregnated with the varnish, and the substrate is evenly and thoroughly impregnated with the varnish.

〔Example〕

The configuration of the present invention will be specifically explained below based on the embodiment shown in FIG.

In the varnish impregnation apparatus shown in FIG. 1, 1 is a base material, 2 is a low viscosity liquid storage tank, 3 is a varnish storage tank, 4 is a thermosyphon chamber, 5 is a base material heating mechanism, 6 is a cooling mechanism, and 7 is a low viscosity liquid storage tank. A viscous liquid evaporation mechanism, 8 a condensate recovery mechanism, and 9 a base material traveling guide mechanism.

The base material 1 is a sheet-like material made of a fibrous material, such as a woven fabric or a non-woven fabric made of synthetic, natural, organic, or inorganic fibers, such as paper,
Glass fiber cloth, glass fiber non-woven fabric.

Carbon fiber cloth, carbon fiber nonwoven fabric, aramid fiber cloth, aramid fiber nonwoven fabric, etc. are used.

The low viscosity liquid storage tank 2 has an open top and stores a predetermined amount of a low viscosity liquid 12 such as a solvent, and the varnish storage tank 3 has an open top and stores a predetermined amount of varnish 13. Overflow weirs 2a, 3b and overflow basins 2b are provided on the side walls of each storage tank 2, 3.
3b, and is designed to keep the liquid level height in each reservoir tank 2, 3 constant. In addition, overflow reservoir 2b.

The liquid 3b is returned to the storage tank 2.3 by a return means (not shown). Further, the low viscosity liquid 12 and the varnish 13 are each maintained at a predetermined temperature by a temperature control device (not shown).

By the way, as the low viscosity liquid 12, one having sufficient wettability to the base material 1 is used. Specifically, a solvent with a viscosity lower than Varnish 13 and 100 cP or less is used, but it is preferable to use a solvent of the same quality as the solvent blended in the varnish to be impregnated.
Further, as the varnish 13, a thermosetting resin varnish is generally used, but other varnishes such as thermoplastic resins, natural resins, solvent-free liquid synthetic resins, liquid natural resins, etc. can also be used.

The thermosiphon chamber 4 is disposed above the two needle reservoirs 2 and 3, and has an inverted U-shape with a cylindrical base material inlet portion 4a and a base material outlet portion 4b vertically disposed on the bottom wall. It is constructed in the shape of a siphon tube. The base material inlet part 4a and the base material outlet part 4b are opened below the liquid levels 12' and 13' of the low-viscosity liquid storage area 2' and the varnish storage area 3', respectively, and are configured to open the liquid inside the thermosyphon chamber 4. It is formed in a thermosyphon region 4' that is sealed by a seal. The thermosyphon chamber 4 also has an inert gas supply pipe 14. Exhaust pipe 15. An oil air pipe 16 is connected. The oil pipe 16 is led to the low viscosity liquid storage tank 2, and is provided with a bleed valve 16a. Note that the peripheral wall of the thermosyphon chamber 4 including the substrate inlet section 4a and the substrate outlet section 4b is configured as a heat insulating wall, and the low viscosity liquid vapor is cooled by the outside air and condensed on the inner wall surface of the thermosyphon chamber 4. It is designed to prevent it from sticking.

The base material heating mechanism 5 includes a heating roll 5a in the thermosyphon chamber 4.
is rotatably provided to follow the rotation of the base material 1. This heating roll 5a heats the base material 1 to a temperature equal to or near the boiling point of the low-viscosity liquid 12 in the thermosyphon region 4', thereby evaporating the low-viscosity liquid 12 impregnated therein. By the way, the heating temperature of the base material by the heating roll 5a is controlled by a temperature control device (not shown), but its evaporation capacity is determined by the maximum amount of evaporation that is impregnated into the base material 1 and brought into the thermosyphon chamber 4. It is said to be sufficient to evaporate viscous liquids. Note that the heating roll 5a may be driven to rotate in the direction in which the substrate 1 passes.In this case, it goes without saying that the circumferential speed of the roll is made to match the traveling speed of the substrate 1.

The cooling mechanism 6 is for cooling and condensing the low-viscosity liquid vapor in the thermosiphon region 4', and includes a first cooling coil 6a disposed above the low-viscosity liquid reservoir 12a at the base material inlet section 4a; , varnish reservoir 13 at the base material outlet section 4b
It consists of a second cooling coil 6b disposed above the cooling coil 6a. By the way, the cooling capacity, that is, the condensing capacity, of the first cooling coil 6a is sufficient to condense all the low-viscosity liquid evaporated by the heating roll 5a. In other words, the evaporation capacity is greater than the evaporation capacity of the heating roll 5a. Further, the condensing capacity of the second cooling coil 6b is the same as that of the first cooling coil 6b.
It is lower than the condensing capacity of A, and is about 10 to 20% of that. Note that each cooling coil 6a, 6b and the peripheral wall of the thermosyphon chamber 4 are insulated, and the cooling coil 6 is connected to this peripheral wall.
This is intended to prevent inconveniences (condensation and adhesion of low-viscosity liquid vapor to the inner surface of the peripheral wall) due to the cooling effect of a and 6b.

The low-viscosity liquid heating mechanism 7 heats and evaporates the low-viscosity liquid in the low-viscosity liquid reservoir 12a, and includes a vertically extending low-viscosity liquid heating surface 7a formed of, for example, a heat transfer coil through which a heating medium flows. is arranged in a low viscosity liquid reservoir 12a. By the way, the heating ability of the low viscosity liquid heating mechanism 7, that is, the low viscosity liquid evaporation ability, is limited to at least the cooling coils 6a, 6.
This is sufficient to ensure the amount of evaporation equivalent to the amount of condensation (total amount) due to b. Note that the low viscosity liquid heating surface 7a
The space between the thermosiphon chamber 4 and the surrounding wall of the thermosyphon chamber 4 is insulated to prevent heat in the low viscosity liquid reservoir 12a from being transmitted to the surrounding low viscosity liquid 12 as much as possible.

The condensed liquid recovery mechanism 8 has a condensed liquid reservoir 8a connected to the inner peripheral part of the base material outlet section 4b directly below the second cooling coil 6b, and collects the low viscosity liquid reservoir 2 (more specifically) from this condensed amount 8a. Specifically, by guiding the tube 8b into the low viscosity liquid reservoir 2b) at the base material inlet portion 4a.

The low viscosity liquid condensed by the second cooling coil 6b is collected into the low viscosity liquid reservoir 2b.

Further, the low viscosity liquid condensed by the first cooling coil 6a is collected into the low viscosity liquid reservoir 2b using the base material inlet portion 4a as it is. The wall 8C constituting the condensation amount 8a is configured as a heat insulating wall that insulates the space between the base material 1 and the second cooling coil 6b, and the base material 1 is radiatively cooled by the cooling coil 6b, thereby achieving low viscosity. This is intended to prevent liquid vapor from condensing and adhering to the base material 1.

The base material traveling guide mechanism 9 consists of guide rolls 9a..., 9b... arranged at least in each storage tank 2.3, and the base material 1 is supplied from a base material supply source (not shown) with low viscosity. The low viscosity liquid heating surface 7a extends into the liquid storage tank 2 from the base material inlet 4a.
It passes through the first cooling coil 6a and reaches the inside of the thermosiphon chamber 4, passes through the heating roll 5a and the second cooling coil 6b, reaches the inside of the varnish storage tank 3 from the base material outlet part 4b, and reaches the top of the varnish storage tank 3. The varnish impregnated amount adjustment mechanism 17 is guided so as to pass through the varnish impregnated amount adjustment mechanism 17. In addition, each storage area 2
Guide rolls 9a...9b arranged at ', 3'
A part of the base material 1 is configured as an expander type that can apply stretching force in the width direction to the base material 1.
A low viscosity liquid storage area 2' in a direction perpendicular to the direction of movement of the
Replacement of air with low viscosity liquid and varnish storage area 3
It is intended to accelerate the varnish impregnation in . The varnish impregnation amount adjustment mechanism 17 is composed of a squeeze roll or a squeeze bar, and squeezes the base material 1 that has passed through the varnish storage tank 3 to adjust the varnish impregnation amount.

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

To start up the device, the inside of the thermosyphon chamber 4 is filled with saturated steam of a low viscosity liquid, and the pressure of the steam is maintained within a certain range as follows.

That is, inert gas is supplied to the thermosiphon chamber 4 from the supply pipe 14, and air in the thermosyphon chamber 4 is removed from the exhaust pipe 15. At this time, the inside of the thermosiphon chamber 4 is maintained at atmospheric pressure. Therefore, the low viscosity liquid reservoir 12a and the varnish reservoir 13
The liquid levels 12'a and 13'a of a are the liquid levels 12 of the storage tanks 2 and 3.
', 13' (see solid line in Figure 1).

Next, each heating mechanism 5, 7 is operated, mainly.

A low viscosity liquid heating mechanism 7 generates low viscosity liquid vapor within the thermosyphon chamber 4. At the same time, only the second cooling coil 6b with low cooling capacity is operated to condense the low viscosity liquid vapor.

Therefore, since the first cooling coil 6a with high cooling capacity is not operated, the amount of evaporation caused by the surface heating mechanisms 5 and 7 exceeds the amount of condensation caused by the second cooling coil 6b, and the vapor pressure in the thermosyphon chamber 4 increases. I will do it.

At this time, when the oil valve 16a is forcibly opened, the excess steam in the thermosyphon chamber 4 is removed from the bleed pipe 16 to the low viscosity liquid storage tank 2, and the inside of the thermosyphon chamber 4 is maintained at atmospheric pressure. .

On the other hand, the sealing liquid levels 12'a and 13'a do not vary and are maintained at the solid line positions in FIG. 1. Further, the low viscosity liquid condensed by the second cooling coil 6b is collected in the condensed liquid reservoir 8a, and is recovered into the low viscosity liquid reservoir 12a from the first recovery pipe 8b. This causes the low viscosity liquid vapor to flow into the varnish storage area 3'.
Condensation on the sides is prevented.

By repeating the actions described in 3, the inert gas in the thermosyphon chamber 4 is expelled, and the chamber 4 is filled with low-viscosity liquid vapor.

When the inside of the thermosyphon chamber 4 is filled with low viscosity liquid vapor, the bleed valve 16a is forcibly closed, and the pressure inside the thermosyphon chamber 4 is increased. At this time, as the pressure within the thermosiphon chamber 4 increases, each sealing liquid surface 12'a.

13'a descends (see the dashed line in Figure 1), and
As the liquid level 12'a of the low-viscosity liquid reservoir 12a falls, the immersion depth of the low-viscosity liquid heating surface 7a in the low-viscosity liquid reservoir 12a, and therefore the contact area between the heating surface 7a and the low-viscosity liquid, decreases. , the amount of evaporation by the low viscosity liquid heating mechanism 7 decreases,
This balances the amount of condensation in the second cooling coil 6b.

Subsequently, when the first cooling coil 6a is operated.

The amount of condensation of the low-viscosity liquid vapor increases, the pressure within the thermosyphon chamber 4 decreases, and the sealing liquid surfaces 12'a, 13' rise.

As the liquid level 12'a of the low-viscosity liquid reservoir 12a rises, the contact area between the low-viscosity liquid heating surface 7a and the low-viscosity liquid increases, and the amount of evaporation by the low-viscosity liquid heating mechanism 7 increases. , the amount of condensation in the cooling coils 6a, 6b is balanced, and the steam pressure in the thermosyphon chamber 4 is maintained within a certain range.

When the base material 1 is run in this state, the base material 1 is impregnated with varnish in the following manner.

That is, the substrate 1 is brought into the low viscosity liquid storage tank 2 from the substrate supply source and immersed in the low viscosity liquid 12, and the air in the substrate 1 is replaced with the low viscosity liquid 12. At this time, base material 1
When the liquid reaches the liquid surface 12' of the low-viscosity liquid 12, the low-viscosity liquid 12 penetrates into the fiber bundle constituting the base material 1 by capillary action, and at the same time, the air in the fiber bundle is pushed out by the penetrating force. Such osmotic action stops at a stage due to osmotic resistance in the fiber bundle. In other words, the cessation of osmosis occurs when the base material 1
When the traveling speed of the fiber bundle, that is, the speed at which the fiber bundle enters the low-viscosity liquid 12 is higher than the permeation speed, it occurs above the liquid surface, and in the opposite case, it occurs below the liquid surface. Therefore, while the base material 1 passes through the low-viscosity liquid storage area 2', all the air in the fiber bundle is replaced with the low-viscosity liquid 12 and eliminated.

Then, the base material 1 impregnated with the low viscosity liquid 12 is brought into the thermosyphon chamber 4 from the base material inlet 4a, heated by the heating roll 5a, and the low viscosity liquid impregnated into the base material 1 is heated by the heating roll 5a. 12 is removed by evaporation.

At this time, since the base material 1 continues to supply the low viscosity liquid 12 to the base material heating section 5a at its advancing speed, the base material 1 plays the role of a wick as a thermosiphon.

On the other hand, the steam pressure in the thermosiphon chamber 4 is maintained within a certain range by the following self-control.

That is, when the steam pressure inside the thermosiphon chamber 4 fluctuates,
Along with this, the liquid level 12'a of the low-viscosity liquid reservoir 12a (and the liquid level 13'a of the varnish reservoir 13a) also changes, and the amount of evaporation by the low-viscosity liquid heating mechanism 7 is automatically adjusted according to the amount of fluctuation. For example, when the steam pressure decreases and the liquid sealing surface 12'a rises, the contact area between the low viscosity liquid in the low viscosity liquid reservoir 12a and the low viscosity liquid heating surface 7a increases. state), the amount of evaporation by the low-viscosity liquid heating mechanism 7 increases by an amount corresponding to the amount of decrease in steam pressure, and a decrease in steam pressure in the thermosyphon chamber 4 is prevented. Conversely, when the steam pressure increases, the sealing liquid surface 12'a falls, and the contact area between the low viscosity expansion and the low viscosity liquid heating surface 7a decreases (for example, the state shown by the chain line), and the low viscosity liquid heating The amount of evaporation caused by the mechanism 7 is reduced, preventing an increase in steam pressure.

Further, most of the steam generated by the base material heating mechanism 5 is condensed by the first cooling coil 6a and collected from the base material inlet portion 4a into the low viscosity liquid reservoir 12a. On the other hand, at the base material outlet section 4b, the low viscosity liquid vapor is condensed by the second cooling coil 6b, and the condensed liquid is collected into the low viscosity liquid reservoir 12a from the collection pipe 8b. As a result, in conjunction with the self-control of steam pressure mentioned above.

The low viscosity liquid is successfully separated from the base material 1, and
Loss of the low viscosity liquid 12 and intrusion into the varnish reservoir 3 will be prevented as much as possible.

Therefore, the base material 1 heated in the thermosyphon chamber 4 only contains saturated vapor of the low viscosity liquid 12, and is brought into the varnish storage tank 3 from the base material outlet part 4b without containing air, and the varnish is It is immersed in 13.

Then, when the low-viscosity liquid-saturated vapor contained in the base material 1 enters the varnish storage region 3', it becomes a trace amount of low-viscosity liquid-saturated liquid and diffuses into the varnish 13.

Therefore, while the base material 1 passes through the varnish storage area 3', the base material 1 is evenly and sufficiently impregnated with the varnish 13.

At this time, as described above, most of the low-viscosity liquid vapor generated in the thermosyphon chamber 4 is recovered to the low-viscosity liquid storage tank 2 side, and the low-viscosity liquid vapor is directly brought into the varnish storage tank 3 by the base material 1. Since the amount of liquid saturated steam is small, the viscosity of the varnish in the varnish storage tank 3 will not decrease.
Further, the base material l has expander type guide rolls 9a, 9.
A stretching force in the width direction is applied when passing through b, and this stretching force is canceled after passing through the rolls, so that the fiber bundles in the width direction are also expanded and reconverged in the low viscosity liquid 12 and varnish 13. This also improves the displacement of air and low viscosity liquid in the width direction and the impregnability of varnish. As a result, the inside of the fiber bundle of the base material 1 is sufficiently impregnated with the varnish 13.

〔Effect of the invention〕

As can be easily understood from the above explanation, according to the method of the present invention, it is possible to impregnate a base material with varnish evenly and in a sufficiently short time, and moreover, it is possible to completely eliminate air bubbles in the base material. Can be done. This effect is significant when impregnating high viscosity varnishes.

Moreover, according to the method of the present invention, fluctuations in steam pressure in the thermosiphon region are interpreted as fluctuations in the liquid sealing surface in the communication portion with the low-viscosity liquid storage region, and low-viscosity liquid vapor is Since the amount generated is controlled, regardless of changes or fluctuations in varnish impregnation conditions such as substrate speed,
The steam pressure in the thermosyphon region can be maintained within a certain range, and good varnish impregnation can be achieved.

Furthermore, in the transition stage from the low viscosity liquid to the varnish, the substrate is heated and most of the low viscosity liquid is evaporated and separated, so loss of the low viscosity liquid and dilution of the varnish can be effectively prevented, and the impregnation effect can be effectively prevented. It is possible to further promote this. Moreover, the amount of low viscosity liquid used in the base material is extremely small, and the amount of exhaust air from the drying oven in the drying step after impregnation with varnish can be significantly reduced.

In addition, according to the apparatus of the present invention, the above method can be carried out suitably, and in particular, the steam pressure in the thermosiphon chamber can be changed by changing the contact area between the low viscosity liquid and the low viscosity liquid heating surface in the low viscosity liquid reservoir. Since the steam pressure control in the thermosiphon chamber is self-controlled, there is no need for a high-precision pressure control device, etc., and the structure of the device does not become unnecessarily complicated or large. This can be done more reliably and accurately than when using a device or the like. moreover.

Even if the thermosyphon chamber becomes a vacuum or negative pressure state when the operation is stopped, etc., this situation can be prevented and low viscosity liquids and varnishes can be sucked up into the thermosyphon chamber. Does not cause any inconvenience.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a varnish impregnating apparatus according to the present invention. 1... Base material, 2... Low viscosity liquid storage tank, 2'... Low viscosity liquid storage area, 3... Varnish storage tank, 3'... Varnish storage area, 4... Heat Siphon chamber, 4'...Thermosiphon region, 4a...Base material inlet portion which is a communication part between the thermosiphon region and the low viscosity liquid storage region, 4b...Communication between the thermosyphon region and the varnish storage region a base material outlet section,
5... Base material heating mechanism, 5a... Heating roll, 6...
- Cooling mechanism, 6a...first cooling coil, 6b...second cooling coil. 7...Low viscosity liquid heating mechanism, 7a...Low viscosity liquid heating surface. 8... Condensed liquid recovery mechanism, 9... Base material traveling guide mechanism. 12...Low viscosity liquid, 12a...Low viscosity liquid reservoir, 12'
a... Liquid level of a low viscosity liquid reservoir serving as a liquid sealing surface, 13... Varnish, 13a... Varnish reservoir, 13'a... Liquid level of a varnish reservoir serving as a liquid sealing surface. ,． 1. ,'y pa″ノ561

Claims (2)

[Claims] (1) A hermetic heat source that communicates between a low-viscosity liquid storage area that stores low-viscosity liquids such as solvents and a varnish storage area that stores varnish in a state where both storage areas are sealed at the liquid level. A siphon area is provided so that the sheet-like base material made of a fibrous material passes through a low viscosity liquid storage area, a thermosyphon area, and a varnish storage area in sequence, and the base material is heated in the thermosiphon area. The low viscosity liquid impregnated in this is evaporated, the low viscosity liquid vapor generated in the area is condensed and liquefied, and the condensed and liquefied low viscosity liquid is collected into the low viscosity liquid storage area, and further The low viscosity liquid is heated and evaporated in the communication area between the thermosyphon area and the low viscosity liquid storage area,
A varnish impregnation method characterized in that the amount of evaporation is controlled in accordance with fluctuations in a liquid sealing surface in the communication portion. (2) a low viscosity liquid storage tank storing a low viscosity liquid such as a solvent;
A varnish storage tank that stores varnish, a sealed thermosiphon chamber with a cylindrical base material inlet and a base material outlet that open below the liquid level in each storage tank, and a fibrous material. A base material traveling guide mechanism that guides a sheet-like base material from a low-viscosity liquid storage tank through a base material inlet to a thermosyphon chamber, and then leads it from a base material outlet to a varnish storage tank, and heats the base material in the thermosiphon chamber. and a base material heating mechanism that evaporates the low viscosity liquid impregnated into the base material, a cooling mechanism that condenses and liquefies the low viscosity liquid vapor in the thermosiphon chamber, and a base material heating mechanism that evaporates the low viscosity liquid impregnated into the base material, and a cooling mechanism that condenses and liquefies the low viscosity liquid vapor in the thermosyphon chamber. A condensate recovery mechanism that collects condensate on the liquid storage tank side and a low-viscosity liquid heating surface that extends vertically in the low-viscosity liquid reservoir in the base material inlet are installed to reduce the condensate as the liquid level changes in the low-viscosity liquid reservoir. A varnish impregnation device comprising: a low viscosity liquid heating mechanism configured to change the amount of heating and evaporation of the viscous liquid.