JPH0581409B2 - - Google Patents

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 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 such an impregnation method, it is difficult to uniformly and sufficiently impregnate the inside of the base material with the varnish, and there are problems in that it takes a long time to impregnate the base material with the varnish. Moreover, 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, in recent years, instead of the normal varnish for preliminary impregnation mentioned above, a preliminary impregnation tank that stores a solvent or a dilute varnish containing a large amount of solvent (hereinafter referred to as "preliminary impregnation liquid") and a main impregnation tank that stores a normal varnish. It has been practiced to arrange these in parallel and allow the base material to pass through the preliminary impregnation tank and the main impregnation tank sequentially using guide rolls.

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.

That is, when the base material reaches the guide roll,
Contact surface pressure acts on the fiber bundles that make up the base material,
The fiber bundle is opened, and the liquid phase of the pre-impregnation liquid held by capillary forces within the fiber bundle is destroyed. The compression of the fiber bundle is released when it passes through this guide roll, but the opened fiber bundle is reformed by this decompression 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 these points,
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 by providing a varnish impregnation method 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 sealed thermosiphon region is provided in both reservoir regions, which communicate with each other while being sealed with liquid at the liquid level, and a sheet-like base material made of a fibrous material is used as a low-viscosity liquid reservoir region, a thermosyphon region, and a varnish reservoir region. In the thermosyphon region, the base material is heated to evaporate the low viscosity liquid impregnated therein, and the low viscosity liquid stored on the outlet side of the base material is evaporated. The generated low-viscosity liquid vapor is made to flow from the outlet side of the base material to at least the heating section 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 below the liquid level in each storage tank. A closed thermosiphon chamber is equipped with a cylindrical base material inlet and a base material outlet that open at a base material running guide mechanism that guides the base material into the siphon chamber and further leads the base material from the base material outlet to the varnish storage tank; a base material heating mechanism that heats the base material in the thermosiphon chamber and evaporates the low viscosity liquid impregnated therein; The base material outlet section is equipped with a low viscosity liquid storage section and a low viscosity liquid heater, which heats and evaporates the low viscosity liquid in the low viscosity liquid reservoir section, and also directs the low viscosity liquid vapor generated in the thermosiphon chamber to the base material outlet section. The steam flow mechanism includes a steam flow mechanism that causes the steam to flow from the side toward at least the base material heating mechanism 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.

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 thermosyphon chamber is filled with low-viscosity liquid vapor generated by the vapor flow mechanism and the substrate heating mechanism, and the vapor is transferred from the substrate outlet side to at least the substrate heating mechanism side by the vapor 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 storage area to the varnish storage area, resulting in a substrate that is not impregnated with air in the varnish area. Furthermore, as the substrate advances, very little of the low-viscosity liquid enters the varnish storage area.

As a result, when the substrate is brought into the varnish storage area, the substrate is well impregnated with varnish, 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 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, and 4
5 is a thermosyphon chamber, 5 is a base material heating mechanism, 6 is a steam flow mechanism, and 7 is a base material traveling guide mechanism.

The base material 1 is a sheet-like material made of fibrous material,
Woven fabrics and nonwoven fabrics made of synthetic, natural, and organic fibers, such as paper, glass fiber fabric, glass fiber nonwoven fabric, carbon fiber fabric, carbon fiber nonwoven fabric, aramid fiber fabric, aramid fiber nonwoven fabric, and the like 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, 3b are provided on the side walls of each storage tank 2, 3, and are designed to keep the liquid level in each storage tank 2, 3 constant. be. In addition, the overflow basin 2b,
The liquid 3b is returned to the storage tanks 2 and 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, it has a lower viscosity than Varnish 13 and
A solvent with a viscosity of 100 cP or less is used, but it is preferable to use a solvent of the same quality as the solvent blended into 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 thermosyphon chamber 4 is a sealed type disposed above the storage tanks 2 and 3, and has a cylindrical base material inlet part 4a and a base material outlet part 4b hanging from the bottom wall. It is configured in a U-shaped approximately siphon tube shape. The base material inlet part 4a and the base material outlet part 4b are the low viscosity liquid storage area 2' in the low viscosity liquid storage tank 2, respectively.
and varnish storage area 3' in varnish storage tank 3
It is opened below the liquid level 12', 13'.
Therefore, inside the base material inlet part 4a and the base material outlet part 4
A low-viscosity liquid reservoir 12a and a varnish reservoir 13a are formed in the thermosiphon chamber 4, forming a thermosiphon region 4' sealed by a liquid seal. Also,
In this embodiment, the peripheral wall 4c of the thermosyphon chamber 4 including the base material inlet part 4a and the base material outlet part 4b is constructed into a jacket structure, and an appropriate heating medium is supplied and made to flow therein. The peripheral wall 4c is heated and kept warm above the boiling point of the low viscosity liquid 12, so that the pressure within the thermosyphon chamber 4 quickly reaches the saturated vapor pressure of the low viscosity liquid 12 when the device is started, that is, a rapid rise is possible. In addition, it is intended to prevent low viscosity liquid vapor from condensing and adhering to the inner surface of the peripheral wall 4c. Of course, the outer wall of the jacket in the peripheral wall 4c is made of a heat insulating material.

The substrate heating mechanism 5 includes a heating roll 5 a rotatably provided in the thermosiphon chamber 4 to follow the movement of the substrate 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. 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. Viscous liquid 12
is said to be sufficient to evaporate the Note that the heating roll 5a may be driven to rotate in the direction in which the base material 1 passes. In this case, it goes without saying that the circumferential speed of the roll should also match the traveling speed of the base material 1.

The vapor flow mechanism 6 is provided with a low viscosity liquid storage section 8 and a low viscosity liquid heater 9 at the base material outlet section 4b, and
A self-control heater 10 is arranged in a low viscosity liquid reservoir 12a. The low viscosity liquid storage part 8 is formed at the lower end of the base material outlet part 4a, and by communicating with the low viscosity liquid storage tank 2, the low viscosity liquid 12a in the low viscosity liquid storage tank 2 can be A fixed amount is stored. The liquid level of this low viscosity liquid storage section 8 is made to match the liquid level 12' of the low viscosity liquid storage tank 2, regardless of the evaporation of the low viscosity liquid in this section 8. 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 into the inside thereof, the low viscosity liquid storage section 8 is heated. The low viscosity liquid 12 is heated and evaporated. The jacket wall of this low viscosity liquid heater 9 is made of a heat insulating material except for the parts that contact the low viscosity liquid reservoir 8 and the varnish reservoir 13a, and the heat is transferred to the varnish reservoir 13a.
It has been devised so that it does not spread to the surrounding varnish 13. 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. Self-controlled heater 1
0 is composed of, for example, a heat transfer coil that supplies and flows a heating medium inside, and is a low viscosity liquid reservoir 12a.
The low viscosity liquid 12 is heated and evaporated. This self-regulating heater 10 uses its evaporation capacity as a low viscosity liquid heater 9.
Although it is smaller than the low viscosity liquid reservoir 12
A low viscosity liquid heating surface 10 extending vertically at a
a, and is configured to be able to self-control its evaporation capacity in response to fluctuations in steam pressure within the thermosyphon chamber 4. That is, as the steam pressure in the thermosiphon chamber 4 decreases or increases, the liquid level in the low-viscosity liquid reservoir 12a (and the liquid level in the varnish reservoir 13a) decreases accordingly.
rises and falls, heating surface 10a and low viscosity liquid 12
Accordingly, the evaporation capacity is automatically adjusted to increase or decrease according to the contact area. Further, an air bleed pipe 11 is connected to the thermosyphon chamber 4, so that the air inside the thermosyphon chamber 4 can be removed. This bleed pipe 11 is led to a low viscosity liquid storage tank 2 via a gas-liquid separator 11a, and is designed so that the low viscosity liquid vapor discharged by the bleed air can be condensed and recovered in the low viscosity liquid storage tank 2. There is.

The substrate traveling guide mechanism 7 includes at least an appropriate number of guide rolls 7a disposed in each of the storage tanks 2 and 3.
..., 7b..., the base material 1 reaches the low viscosity liquid storage area 2' in the low viscosity liquid storage tank 2 from the base material supply source,
The base material inlet part 4a reaches the thermosyphon region 4' in the thermosiphon chamber 4, passes through the heating roll 5a, and reaches the varnish storage region 3' in the varnish storage tank 3 from the base material outlet part 4b, and the varnish storage tank 3 so that it passes through the varnish impregnation amount adjustment mechanism 14 on the top. Note that some of the guide rolls 7a..., 7b... disposed in each of the storage areas 2', 3' are configured as expander type rolls that can apply stretching force to the base material 1 in its width direction. base material 1
Displacement 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 varnish storage area 3' are promoted. 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.

Note that a heating roll 5a is provided in the thermosyphon chamber 4.
A cylindrical heating wall (or heat insulating wall) that surrounds the base material 1 along the base material passage path from the varnish reservoir 13a to the varnish reservoir 13a.
15, and the base material 1 is heated and kept warm to a temperature higher than the condensation temperature of the low-viscosity liquid vapor during this time.

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

First, the air in the thermosiphon chamber 4 is removed by the air bleed pipe 11, and the low viscosity liquid 12 in the low viscosity liquid reservoir 8 and the low viscosity liquid reservoir 12a is heated and evaporated by the heaters 9 and 10, and 4 is filled with low viscosity liquid vapor.

Thereafter, when the substrate 1 is run, the substrate 1 is brought from the substrate supply source into the low viscosity liquid reservoir 2 and is immersed in the low viscosity liquid 12, so that the air in the substrate 1 becomes low. It is replaced with viscous liquid 12.

At this time, the base material 1 is at the liquid level 1 of the low viscosity liquid storage tank 2.
2', 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 extracted by its penetrating power. Such osmotic action stops at some stage due to osmotic resistance in the fiber bundle. In other words, the stopping of the permeation action is determined by the traveling speed of the base material 1, that is, the low viscosity liquid 1 of the fiber bundle.
If the rate of entry into 2 is greater than the rate of penetration, it will occur above the liquid level 12', and vice versa, it will occur below the liquid level 12'.

Therefore, while the base material 1 passes through the low viscosity liquid storage area 2', the expander type guide roll 7a
Coupled with this, all the air in the fiber bundle is replaced with the low viscosity liquid 12 and eliminated.

The base material 1 impregnated with the low viscosity liquid 12 is
The low viscosity liquid 12 impregnated into the base material 1 is evaporated and removed by being brought into the thermosyphon chamber 4 from the base material inlet portion 4a and heated by the heating roll 5a.

At this time, the low viscosity liquid vapor generated in the thermosiphon chamber 4 is caused to reach the base material outlet as shown in FIG. The air flows from the part 4b side to the base material heating part 5a side and further to the base material inlet part 4a side, and at least the part of the base material passage area from the base material heating part 5a to the varnish reservoir 13a is free of air. is maintained in a saturated vapor atmosphere with low viscosity liquid absent. In addition, 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 thermosyphon. Further, the low-viscosity liquid vapor generated in the thermosyphon chamber 4 is condensed and recovered in the low-viscosity liquid storage area 2' by the bleed operation using the air bleed pipe 11 or the condensation action in the low-viscosity liquid reservoir 12a.

The base material 1 that has passed through the heating roll 5a is
Subsequently, it passes 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 base material 1 and its surroundings are heated and kept warm by the heating wall 15 and the heater 9 to a temperature higher than the condensation temperature of the low-viscosity liquid vapor, the base material passage area from the heating roll 5a to the varnish reservoir 13a is A complete low-viscosity liquid-vapor atmosphere is maintained, and the low-viscosity liquid-vapor in the base material passage area is condensed and attached to the base material surface or varnish reservoir 13.
There is no possibility of intrusion into a.

Incidentally, since the varnish temperature is generally lower than the saturated vapor temperature of a low-viscosity liquid, when the base material 1 enters the varnish 13, the low-viscosity liquid vapor contained therein will be condensed.

However, the liquid level of the varnish reservoir 13a is
Since the low viscosity liquid 12 is heated to a temperature higher than the boiling point of the low viscosity liquid 12, the condensed liquid generated when entering the varnish reservoir 13a as described above is re-evaporated and the varnish 13
It hardly ever gets inside.

For these reasons, there is almost no risk that the low-viscosity liquid 12 will enter the varnish 13 as the base material 1 enters, and there is no fear that the varnish 13 will be 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. . 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, in the vapor flow mechanism 6, as shown in FIG. 2, a cooler 16 such as a cooling coil may be provided on the base material inlet portion 4a side instead of the control heater 10.
The low viscosity liquid vapor generated in the thermosyphon chamber 4 is condensed by the cooler 16 and collected into the low viscosity liquid reservoir 12a, resulting in the flow of the above-described low viscosity liquid vapor. In this case, the air bleed pipe 11 is
Not particularly necessary. Also, on the side of the base material inlet 4a, as shown in FIG. 3, the heater 11 and the cooler 16 are provided.
It is also possible to provide neither of these.

Further, as shown in FIG. 3, the upper surface of the low-viscosity liquid storage tank 2 is closed with a lid 2c having an inlet 2d for the base material 1, and a cooling mechanism such as a cooling coil is connected to the inlet 2d.
7 may be arranged. In this way, it is possible to reliably prevent the low viscosity liquid 12 from dispersing, thereby preventing environmental pollution and loss of the low viscosity liquid, and even if it is flammable, it can be safely used as the low viscosity liquid 12. Can be used. Such a configuration can also be applied to the varnish storage tank 3.

Further, as shown in FIG. 4, a low viscosity liquid recovery section 18 may be provided at the base material outlet section 4b and communicated with the low viscosity liquid storage section 8 a. In this case, the cooler 16 is disposed in the low viscosity liquid recovery section 18 so that the low viscosity liquid vapor is condensed and recovered in the low viscosity liquid recovery section 18 .

In addition, if there is a risk that the solvent etc. in the varnish 13 will evaporate by heating the varnish reservoir 13a and enter the thermosyphon chamber 4, the varnish 1
By making the substrate passageway at the substrate exit portion 4b portion immersed in the substrate 3 as narrow as possible within the range through which the substrate 1 can pass, the boundary area between the varnish storage region 3' and the thermosyphon region 4', that is, The varnish surface area within the base material outlet portion 4b may be made small. By doing this, the 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 the invasion of the evaporation into the thermosyphon chamber 4 can be prevented as much as possible by advancing the base material 1. can be prevented. Furthermore, condensation of low-viscosity liquid vapor on the liquid surface of the varnish reservoir 13a can be prevented as much as possible.

Furthermore, a nozzle for blowing low-viscosity liquid vapor may be provided on the peripheral wall of the thermosyphon chamber 4, for example, on the peripheral wall of the base material outlet section 4b. In this way, in combination with the heating effect of the peripheral wall 4c of the thermosiphon chamber 4, it is possible to achieve a more rapid start-up at the time of starting the apparatus.

〔Effect of the invention〕

As can be easily understood from the above description, according to the present invention, a base material can be impregnated with varnish uniformly and in a sufficiently short time, and there can be no 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 to 4 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...Thermosyphon chamber, 4'...
...thermosyphon region, 4a...base material inlet portion, which is a communication part between the thermosiphon region and the low viscosity liquid storage region, 4
b...Base material outlet part which is a communication part between the thermosiphon region and the varnish storage region, 5...Base material heating mechanism, 5a
. . . Heating roll, 6 . . . Steam flow mechanism, 7 . . . Base material traveling guide mechanism, 7a, 7b .

Claims (1)

[Claims] 1. 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 sealed thermosiphon region is provided in both reservoir regions, which communicate with each other while being sealed with liquid at the liquid level, and a sheet-like base material made of a fibrous material is used as a low-viscosity liquid reservoir region, a thermosyphon region, and a varnish reservoir region. In the thermosyphon region, the base material is heated to evaporate the low viscosity liquid impregnated therein, and the low viscosity liquid stored on the outlet side of the base material is evaporated. A varnish impregnation method characterized in that the generated low-viscosity liquid vapor is made to flow from the outlet side of the base material to at least the heating part side of the base material. 2 A low viscosity liquid storage tank that stores low viscosity liquid such as a solvent, a varnish storage tank that stores varnish, and a cylindrical base material inlet and base material outlet that open below the liquid level in each storage tank. A sealed thermosiphon chamber equipped with
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 varnish characterized by comprising: a vapor flow mechanism that heats and evaporates the low viscosity liquid and causes the low viscosity liquid vapor generated in the thermosiphon chamber to flow from the base material outlet side to at least the base material heating mechanism side. Impregnation equipment.