JPH02214615A - Method and equipment for varnishing - Google Patents

Abstract

PURPOSE:To enhance varnishing properties and voidless effect in base material by providing a closed thermosiphon region which is opened on the liquid surface of a low viscous liquid storage region and opened under the liquid surface of a varnish storage region. CONSTITUTION:While base material 1 is passed through a low viscous liquid storage region 2', the air in fiber bundle is thoroughly replaced by low viscous liquid 12 and discharged. This base material is introduced into a thermosiphon chamber 4 through an inlet part 4a opened on the liquid surface 12'. The base material 11 is heated by a heating roll 5a in the chamber 4 and low viscous liquid 12 impregnated therein is evaporated and separated. At this time, vapor of low viscous liquid which is generated in the chamber 4 is condensed by a cooler 11 and recovered in a low viscous liquid recovery part 10. Successively the base material 1 is passed through a varnish reservoir 13a from an outlet part 4b and introduced into a varnish storage region 3' and impregnated with varnish 13. At this time, the base material 11 is free from air and therefore even the inside of fiber is uniformly and sufficiently impregnated with varnish 13.

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.

[Traditional technique]

Generally, when impregnating a sheet-like base material made of fibrous material with varnish, it is important that the varnish is impregnated into 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 inside as much as possible.

In conventional impregnation methods, the substrate is generally pre-impregnated with an ordinary varnish for pre-impregnation, and then guided through a timing roll to a varnish tank where it is impregnated with an ordinary 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 this point.

The 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.

[Means to solve the problem]

The varnish impregnation method of the present invention solves this problem, and the varnish impregnation method of the present invention provides a method for impregnating a liquid on the liquid surface of the low viscosity liquid storage area between a low viscosity liquid storage area where a low viscosity liquid such as a solvent can be stored and a varnish storage area where varnish can be stored. A self-closed thermosyphon region is provided which opens below the liquid surface of the varnish storage region, and a sheet-like base material made of a fibrous material is used as a low-viscosity liquid storage region, a thermosyphon region, and a varnish storage region.

in the thermosiphon region,
The base material is heated to evaporate the low viscosity liquid impregnated into the base material, and the low viscosity liquid stored on the outlet side of the base material is evaporated, and the low viscosity liquid vapor generated in the thermosyphon region is evaporated to the outlet side of the base material. The liquid is made to flow from the base material to the inlet side of the base material.

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 of the low viscosity liquid storage tank. A sealed thermosiphon chamber with a base material inlet opening at the top and a base material outlet opening below the liquid surface of the varnish storage tank, and a low-viscosity liquid storage tank containing a sheet-like base material made of fibrous material. A base material running guide mechanism that guides the base material from the base material through the base material inlet to the thermosyphon chamber and further leads the base material from the base material outlet to the varnish storage tank; It is equipped with a base material heating mechanism for evaporation, a low viscosity liquid reservoir and a low viscosity liquid heater at the base material outlet, and it heats and evaporates the low viscosity liquid in the low viscosity liquid reservoir and also heats the low viscosity liquid generated in the thermosyphon chamber. The apparatus includes a vapor flow mechanism that causes viscous liquid vapor to flow from the base material outlet side to the base material inlet side.

[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.

Subsequently, the substrate impregnated with the low viscosity liquid leaves the low viscosity liquid reservoir and is brought into the thermosyphon chamber through the substrate inlet opening above the liquid level.

At this time, the base material comes into contact with air, but since the base material is impregnated with a low-viscosity liquid, air will not re-enter before entering the thermosyphon chamber.

Then, the base material brought into the thermosyphon chamber is heated by the base material heating mechanism, and the low viscosity liquid impregnated therein is evaporated and separated.

At this time, the thermosiphon chamber is filled with low-viscosity liquid vapor generated by the steam flow mechanism and the base material heating mechanism, and the steam is transferred from the base material outlet side to the base material inlet side by the steam flow mechanism. As a result, at least the substrate passage area from the substrate heating mechanism to the substrate outlet is maintained in a low-viscosity liquid-saturated vapor atmosphere that does not contain air.

The substrate will therefore be brought from the thermosyphon chamber into the varnish reservoir containing only saturated vapor of a low viscosity liquid. 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 storage area, the substrate is impregnated with varnish well, and the substrate is evenly and thoroughly impregnated with varnish in an air-free manner.

[Example] Hereinafter, the configuration of the present invention will be specifically explained based on the example 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 steam flow mechanism, and 7 is a This is a base material traveling guide mechanism.

The base material 1 is a sheet-like material made of fibrous material, which may be synthetic, natural, organic, or V! , woven fabrics made of machine fibers, nonwoven fabrics 1 such as paper, glass fiber cloth, glass fiber nonwoven fabrics.

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, 3a 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 located above between the two injection tanks 2 and 3! It is constructed in the shape of an inverted U-shaped substantially siphon tube including a cylindrical base material inlet part 4a and a base material outlet part 4b hanging from the bottom wall. The base material inlet portion 4a is opened just above the liquid level 12' of the low viscosity liquid storage tank 2, and the base material outlet part 4b is opened below the liquid level 13' of the varnish storage tank 3. Further, in this embodiment, the base material entrance portion 4a
By configuring the peripheral wall 4c of the thermosiphon chamber 4 other than the outside in a jacket structure, and supplying and flowing an appropriate heating medium inside the peripheral wall 4c, the peripheral wall 4c is heated to a temperature higher than the boiling point of the low-viscosity liquid 12, kept warm, and the device is started. At the same time, the pressure inside the thermosyphon chamber 4 is designed to quickly reach the saturated vapor pressure of the low-viscosity liquid 12, that is, to enable a rapid rise, and the low-viscosity liquid vapor condenses and adheres to the inner surface of the peripheral wall 4C. We are trying to prevent this from happening.

Of course, the outer wall of the jacket in the first circumferential wall 4c and the circumferential wall of the base material inlet portion 4a are made of a heat insulating material.

Note that an air bleed pipe or the like may be connected to the thermosyphon chamber 4 as necessary.

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 higher than the boiling point of the low-viscosity liquid 12 in the thermosyphon region 4' in the thermosyphon chamber 4, and evaporates the low-viscosity liquid 12 impregnated therein. Incidentally, the temperature at which the base material is heated 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 the viscous liquid 12. 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 vapor flow mechanism 6 includes a low viscosity liquid storage section 8 at the base material outlet section 4b.
and a low viscosity liquid heater 9, and a base material inlet portion 4a.
A low viscosity liquid recovery section 10 and a cooler 11 are provided at the bottom. The same low viscosity liquid as the low viscosity liquid 12 in the low viscosity liquid storage tank 2 is stored in the low viscosity liquid storage section 8 and the low viscosity liquid recovery section 10, and both parts 8 and 10 are in communication with each other 8a. . The low viscosity liquid heater 9 is composed of a jacket structure wall surrounding the low viscosity liquid storage section 8, and by supplying and flowing an appropriate heating medium inside the jacket structure wall, the low viscosity of the low viscosity liquid storage section 8 is reduced. The liquid 12 is heated and evaporated. The jacket wall of this low viscosity liquid heater 9 (and the surrounding wall of the low viscosity liquid recovery section 10) is connected to the low viscosity liquid storage section 8 and the base material outlet section 4.
It is made of a heat insulating material except for the part in contact with the varnish reservoir 13a inside b, and the heat is transferred to the varnish 1 around the varnish reservoir 13a.
This is done in a way that does not convey the message to 3. In this embodiment, the low viscosity liquid heater 9 is configured as a series of jacket structure walls communicating with the peripheral wall 4c of the thermosiphon chamber 4. The cooler 11 is a cooling coil or the like disposed within the low-viscosity liquid recovery section 10, and is used to condense the low-viscosity liquid vapor in the thermosiphon chamber 4 and recover it in the low-viscosity liquid recovery section 10.

The substrate traveling guide mechanism 7 includes at least an appropriate number of guide rolls 7a...7b... disposed within each storage tank 2.3.
The base material 1 reaches from the base material supply source to the low viscosity liquid storage area 2' in the low active liquid p storage tank 2, and from the base material inlet part 4a to the thermosiphon area 4' in the thermosiphon chamber 4, The material is guided so that it passes through the heating roll 5a, reaches the varnish storage area 3' in the varnish storage tank 3 from the base material outlet part 4b, and passes through the varnish impregnation amount adjustment mechanism 14 on the varnish storage tank 3. . Note that some of the guide rolls 7a..., 7b... disposed in each of the storage areas 2', 3' are expander-type rollers that can apply stretching force to the base material 1 in its width direction. and promotes replacement of air and low viscosity liquid in the low viscosity liquid storage area 2' and varnish impregnation in the varnish storage area 3' in the direction perpendicular to the direction of movement of the base material 1. I am trying to make this happen. Further, the varnish impregnation amount adjustment mechanism 14 is composed of a squeeze roll or a squeeze bar, and the varnish impregnation amount adjustment mechanism 14 is composed of a squeeze roll or a squeeze bar.
Squeeze to adjust the amount of varnish impregnated.

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

The base material 1 is run after the inside of the thermosiphon chamber 4 is filled with low viscosity liquid vapor.

First, the substrate 1 is brought into the low viscosity liquid reservoir 2 from a substrate supply source and immersed in the low viscosity liquid 12 .

Air in the substrate 1 is replaced with a low viscosity liquid 12.

At this time, when the base material 1 reaches the liquid level 12' of the low-viscosity liquid storage tank 2, the low-viscosity liquid 12 permeates into the fiber bundles constituting the base material 1 by capillary action, and at the same time, the fiber bundles The air inside is forced out. The osmotic action stops at a stage due to the osmotic resistance in the fiber bundle. In other words, if the traveling speed of the base material 1, that is, the speed at which the fiber bundle penetrates into the low-viscosity liquid 12 is higher than the permeation speed, the permeation action stops.
2' and vice versa below the liquid level 12'.

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, together with the action of the expander-type guide roll 7a. will be excluded.

Subsequently, the substrate 1 impregnated with the low viscosity liquid 12 leaves the low viscosity liquid storage area 2' and is brought into the thermosiphon chamber 4 through the substrate inlet 4a opening above the liquid level 12'.

At this time, the base material 1 comes into contact with air, but the base material 1
Since it is impregnated with a low viscosity liquid, air will not re-enter before it enters the thermosyphon chamber 4.

The base material 1 brought into the thermosyphon chamber 4 is heated by the heating roll 5a, and the low viscosity liquid 12 impregnated therein is evaporated and separated.

At this time, the low viscosity liquid vapor generated in the thermosyphon chamber 4 is condensed by cooling [111] and collected in the low viscosity liquid recovery section 10. Therefore, together with the generation of low viscosity liquid vapor in the base material outlet section 4b, that is, the low viscosity liquid storage section 8,
As shown in FIG. 1, the low-viscosity liquid vapor in the thermosyphon chamber 4 is caused to flow from the base material outlet section 4b side to the base material inlet section 4a side, and is at least drained from the base material heating section 5a to the varnish reservoir. The base material passing region portion reaching 13a is maintained in a low viscosity liquid saturated vapor atmosphere free of air.

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

Then, the base material 1 that has passed through the heating roll 5a continues to pass through the varnish reservoir 13a from the base material outlet portion 4b, and is brought to the varnish reservoir region 3'.

At this time, since the varnish temperature is generally lower than the saturated vapor temperature of the low viscosity liquid, when the base material 1 enters the varnish 13,
The low viscosity liquid vapor contained in this will be condensed. However, since the liquid level portion of the varnish reservoir 13a is heated by the heater 9 to a temperature higher than the boiling point of the low viscosity liquid 12,
As described above, the condensed liquid generated when entering the varnish reservoir 13a is re-evaporated and hardly enters into the varnish 13.

From these facts, as the base material 1 enters, the low viscosity liquid 12
There is almost no possibility that the varnish 13 will enter the varnish 13.
There is no need to worry about it being diluted.

The substrate 1 thus brought into the varnish storage area 3' is impregnated with varnish 13 while passing through this area 3'.

At this time, since the base material 1 does not contain air, the varnish 13 is evenly and sufficiently impregnated into the fibers thereof, together with the action of the expander type guide rolls 7b. become. As a result, a void-free prepreg of extremely high quality can be obtained.

By the way, the present invention is not limited to the above embodiments, and various changes and improvements can be made without departing from its basic principles.

For example, as shown in FIG. 2, the upper surface area of the low-viscosity liquid storage tank 2 communicating with the base material inlet 4a is closed with a lid 2c having an inlet 2d of the base 1, and a cooling coil is connected to the inlet 2d. Alternatively, a cooling mechanism 17 such as the
Environmental pollution and loss of the low viscosity liquid can be prevented, and even flammable liquids can be safely used as the low viscosity liquid 12. Such a configuration can also be applied to the varnish storage tank 3.

Further, as shown in FIG. 3, the low viscosity liquid collection section 10 is not provided, and the low viscosity liquid storage section 8 is communicated 8a with the low viscosity liquid storage region 2'.
In this case, a cooler 11 is provided at the base material inlet portion 4a, but this cooler 11 may be omitted if necessary.

Also, by heating the varnish reservoir 13a, the varnish 13
If there is a risk that the solvent etc. inside will evaporate and enter the thermosyphon chamber 4, the base material 1 may pass through the base material passage in the base material outlet portion 4b portion immersed in the varnish 13. The varnish storage area 3' is made as narrow as possible within the range.
The boundary area between
The surface area of the varnish within b may be kept small. By doing this, evaporation of the solvent, etc. in the varnish 13 due to heating of the varnish reservoir 13a can be prevented as much as possible, and
Intrusion of the steam into the thermosiphon chamber 4 can be prevented as much as possible by advancing the base material 1. Furthermore, condensation of low-viscosity liquid vapor on the liquid surface of the varnish reservoir 13a can be prevented as much as possible. Also,
The base material passageway in the base material inlet portion 4a may also be made as narrow as possible so that steam leakage is prevented as the base material 1 advances. For example, the base material outlet section 4b
A nozzle for blowing low-viscosity liquid vapor may be provided on the peripheral wall of the thermosyphon chamber 4. In this way, in combination with the heating effect of the peripheral wall 4c of the thermosyphon chamber 4, a rapid start-up at the time of starting the device can be achieved. It is possible to further improve the results.

In addition, a heating wall (or a heat insulating wall) having a cylindrical shape or the like surrounding the base material 1 along the base material passing path from the heating roll 5a to the varnish reservoir 13a is disposed in the thermosyphon chamber 4. In this case, the base material 1 may be heated to a temperature higher than the condensation temperature of the low-viscosity liquid vapor and kept warm.

〔Effect of the invention〕

As can be easily understood from the above description, according to 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. . This effect is significant when impregnating high viscosity varnishes.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing one embodiment of the varnish impregnating apparatus according to the present invention, and FIGS. 2 and 3 are longitudinal sectional side views corresponding to FIG. 1 showing modifications thereof. 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'...thermosyphon area, 4a...substrate inlet section, 4b...substrate outlet section, 5...substrate heating mechanism, 5a...heating roll,
6... Steam flow mechanism, 7... Base material traveling guide mechanism,
7a, 7b...Guide roll, 8...Low viscosity liquid reservoir, 9...Low viscosity liquid heater.

Claims (2)

[Claims] (1) 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 varnish can be stored, there is an opening above the liquid level of the low viscosity liquid storage area and below the liquid level of the varnish storage area. A sealed thermosyphon region is provided which opens into the thermosiphon region, and a sheet-like base material made of a fibrous material is passed sequentially through a low viscosity liquid storage region, a thermosyphon region, and a varnish storage region. The material is heated to evaporate the low viscosity liquid impregnated into it, and the low viscosity liquid stored on the outlet side of the base material is evaporated, and the low viscosity liquid vapor generated in the thermosyphon region is evaporated from the outlet side of the base material. A varnish impregnation method characterized by causing the varnish to flow toward the entrance side of the base material. (2) a low viscosity liquid storage tank storing a low viscosity liquid such as a solvent;
A varnish storage tank storing varnish, a sealed thermosyphon chamber comprising a base material inlet opening above the liquid level of the low viscosity liquid storage tank and a base material outlet opening below the liquid level of the varnish storage tank. ,
A base material traveling guide mechanism that guides a sheet-like base material made of a fibrous material from a low-viscosity liquid storage tank through a base material inlet to a thermosyphon chamber, and further guides the base material from a base material outlet to a varnish storage tank; It is equipped with a base material heating mechanism that heats the base material and evaporates the low viscosity liquid impregnated into the base material, and a low viscosity liquid reservoir and a low viscosity liquid heater at the base material outlet. a vapor flow mechanism that heats and evaporates the low-viscosity liquid and flows the low-viscosity liquid vapor generated in the thermosiphon chamber from the base material outlet side to the base material inlet side. Device.