JPH02111472A - Method and device for impregnation of varnish - Google Patents

Abstract

PURPOSE:To obtain the method and device for impregnation of varnish which greatly improves an impregnation characteristic and voidless effect by passing a sheet-like base material in a low-viscosity liquid and passing the material in varnish while averting the contact with air. CONSTITUTION:The sheet-like base material 1 is immersed from a base material supplying source 1' into the low-viscosity liquid (a) in a low viscosity liquid storage tank 2 and the air in the sheet-like base material 1 is substd. with the low-viscosity liquid 2a. The sheet-like base material 1 immersed in the low-viscosity liquid 2a passes between squeezing rolls 9 and 9 and is crimped by the rolls without coming into contact with the air and, therefore, the low viscosity liquid 2a impregnated therein is squeezed out. The sheet-like base material 1 brought into a varnish storage tank 3 is reformed by the pressure release effect arising from the passage between the squeezing rolls 9 and 9 and, therefore, the rapid impregnation of the varnish 3a takes place.

Description

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

[Conventional technology]

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

Traditional impregnation methods generally involve sheet-like substrates.

After pre-impregnating this with regular varnish for pre-impregnation,
Pass through a timing roll and lead to a varnish bath.

Usually, it is impregnated with varnish.

However, with such an impregnation method, it is difficult to sufficiently and uniformly impregnate the inside of the sheet-like base material with varnish, and there is a problem that it takes a long time to impregnate the varnish6. It is difficult to sufficiently reduce the number of air bubbles remaining in the sheet-like base material. This problem becomes particularly noticeable when a high viscosity varnish is used.

Therefore, as shown in FIG. 5, in place of the above-mentioned normal varnish for pre-impregnation, preliminary impregnation is being carried out in which a solvent or a dilute varnish containing a large amount of solvent (hereinafter referred to as "pre-impregnating liquid") 13'a is stored. The tank 13' and the main impregnation tank 13 in which the normal varnish 13a is stored are placed side by side, and the sheet-like base material 11 is made to pass through the preliminary impregnation tank 13' and the main impregnation tank 13 sequentially by guide rolls 14... things are being done.

According to this impregnation method, while the sheet-like base material 11 is passed through the preliminary impregnation liquid 13'a, the sheet-like base material 1
The air in the sheet-like substrate 11 is replaced with the pre-impregnating liquid 13'a and removed.

By bringing the pre-impregnation liquid 13'a impregnated into the varnish 13 while evaporating it, the varnish 13 can be efficiently impregnated and bubbles can be reduced.

[Problem to be solved by the invention]

However, in the transition stage from the preliminary impregnating liquid 13'a to the varnish 13, the sheet-like base material 11 is exposed to air and is subjected to a compression action by the guide roll 14' between the two tanks 13, 13'. Air in the shaped base material 11 is not sufficiently removed, and varnish impregnating properties and void-free effects cannot be expected to be very good.

That is, when the sheet-like base material 11 reaches the guide roll 14', contact surface pressure acts on the fiber bundles constituting the sheet-like base material 11, causing the fiber bundles to open, thereby creating capillaries within the fiber bundles. The force causes the liquid phase of the pre-impregnation liquid 13'a to be destroyed. and.

When the fiber bundle passes through the guide roll 14', the compression of the fiber bundle is released, and the opened fiber bundle is reformed by this decompression action. In this way, since the destruction of the impregnated liquid phase in the fiber bundle and the reformation of the opened fiber bundle are carried out in the air, the sheet is There is a risk that air may re-enter the shaped base material 11.

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

[Means to solve the problem]

The varnish impregnation method of the present invention solves this problem by passing a sheet-like base material made of a fibrous material through a low viscosity liquid such as a solvent, and then passing it through a varnish without exposing it to air. This is what I did.

In such a method, it is preferable to apply pressure to the sheet-like base material during the transition from the low-viscosity liquid to the varnish.

By the way, as a sheet-like base material, synthetic, natural organic,
Woven fabrics and nonwoven fabrics made of inorganic fibers 1, such as paper, glass fiber fabrics, glass fiber nonwoven fabrics, carbon fiber fabrics, carbon fiber nonwoven fabrics, and aramid fiber fabrics.

Aramid fiber non-woven fabric etc. are used.

Further, as the varnish, thermosetting resin varnish is generally used, but varnishes of thermoplastic resins, natural resins, etc., solvent-free liquid synthetic resins, liquid natural resins, etc. are also used. Specifically, a varnish having a composition as exemplified in the table below is used.

<Varnish composition> In addition, as the low viscosity liquid, one that has sufficient wettability for the sheet-like substrate is used.6 Specifically, a solvent etc. that has a viscosity lower than that of the varnish and a viscosity of 100 cP or less is used. However, it is preferable to use a solvent of the same quality as the solvent blended in the varnish to be impregnated. For example, when using a varnish having the above composition, methyl ethyl ketone or the like is used as a blending solvent. This is because if such a varnish-blended solvent is used, there will be no problem even if a low-viscosity liquid is mixed into the varnish.

On the other hand, the varnish impregnation device of the present invention for carrying out such a method has a low viscosity liquid storage tank storing a low viscosity liquid, a varnish storage tank storing varnish, and a bifold tank between which the liquid is stored below the surface of the stored liquid. A base material passageway that communicates with the sheet-like base material, a guide mechanism that guides the sheet-like base material to pass through the low-viscosity storage tank, the base material passageway, and the varnish storage tank in sequence, and a sheet-like base material that is passing through the base material passageway. It is equipped with a squeezing mechanism that applies compressive force to the material in the direction of its thickness.

In such a device, the squeezing mechanism includes a pair of squeezing rolls that are disposed facing each other in the substrate passageway, and passes the sheet-like substrate under pressure while shielding and sealing the two-fold reservoir in the substrate passageway. It is preferable to configure the system so that the

[Effect]

While the sheet-like base material passes through the low-viscosity liquid, air in the sheet-like base material is replaced with the low-viscosity liquid and eliminated.

Subsequently, the sheet-like substrate is passed through a varnish, during which time the low-viscosity liquid impregnated into the sheet-like substrate is replaced by the varnish. At this time, since the transition from the low-viscosity liquid to the varnish takes place without contact with air, air does not re-enter the sheet-like base material during the transition stage, and the varnish contains air. This results in a sheet-like substrate that does not Therefore, varnish impregnation can be performed satisfactorily (1), and the sheet-like substrate can be evenly and sufficiently impregnated with varnish.

Especially in the transition stage from low viscosity liquid to varnish.
When a compressive force is applied to the sheet-like base material in the thickness direction, the low-viscosity liquid impregnated into the sheet-like base material 1 is squeezed out, and the loss of the low-viscosity liquid and the dilution of the varnish are prevented. Prevented as much as possible.

Moreover, since the fiber bundles of the sheet-like base material opened by the compression action are re-formed by the decompression action at the stage of transfer into the varnish, impregnation with the varnish is carried out quickly.

〔Example〕

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

In the varnish impregnation device shown in FIG.
3 is a varnish storage tank that stores varnish 3a, 4 is a guide mechanism, and 5 is a throttle mechanism.

Both injection reservoir tanks 2 and 3 are constructed by partitioning rectangular box-shaped tanks with an open top by partition walls 6. Both firing tanks 2 and 3 are
They are connected to each other via a base material passageway 7 formed in the partition wall 6 below the level of the stored liquid.

The guide mechanism 4 is arranged on the low viscosity liquid storage tank 2 and each storage tank 2,
A sheet-like base material 1 is transported from a base material supply source 1' to a low viscosity liquid storage tank 2. Base material passageway7. It guides the guide to pass through the varnish reservoir 3 one after another. In addition.

A varnish impregnation amount adjusting mechanism 8 consisting of a squeeze roll or a squeeze bar is disposed on the varnish storage tank 3, and the varnish impregnation amount is adjusted by squeezing the sheet-shaped material 1 that has passed through the varnish storage tank 3. It has been devised so that it can be adjusted.

The squeezing mechanism 5 includes a pair of upper and lower squeezing rolls 9 in the substrate passageway 7.
, 9 are rotatably arranged. Both squeezing rolls 9, 9 are made of an elastic material such as rubber, and are held in a state in which their circumferential surfaces are in pressure contact with each other and with the circumferential surface of the substrate passageway 7. The sheet-like base material 1 can be passed through under pressure while the space between the elbow reservoirs 2 and 3 is shielded and sealed. Note that the squeezing rolls 9, 9 may be driven to rotate in the direction in which the sheet-like base material 1 passes. Needless to say, the peripheral speed of the roll in this case is made to match the traveling speed of the sheet-like base material 1.
Each squeezing roll 9 may have an expansion roll structure in which a pressure supply chamber is formed inside.

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

First, the sheet-like substrate 1 is brought into the low-viscosity liquid storage tank 2 from the substrate supply source 1' and immersed in the low-viscosity liquid 2a,
The air in the sheet J& material 1 is replaced with the low viscosity liquid 2a. That is, when the sheet-like base material 1 reaches the liquid level of the low-viscosity liquid 2a, the low-viscosity liquid 2a flows through the sheet-like base material 1 due to capillary action.
At the same time, the air in the fiber bundle la is pushed out by its penetrating force.

Such osmotic action stops at a stage due to osmotic resistance in the fiber bundle 1a. In other words, the permeation action is stopped when the traveling speed of the sheet-like base material 1, that is, the low viscosity liquid 2 of the fiber bundle 1a is stopped.
When the penetration speed v1 into a is higher than the penetration speed v2, it occurs above the liquid surface (see FIG. 2 (A)), and when 1 - v2, it occurs below the liquid surface (see FIG. 2 (B)).

Therefore, while the sheet-like base material 1 passes through the low-viscosity liquid 2a, all the air in the fiber bundle 1a is replaced with the low-viscosity liquid 2a and eliminated.

The sheet-like base material 1 impregnated with the low-viscosity liquid 2a is
The varnish is brought into the varnish reservoir 3 by passing between the squeezing rolls 9.9 without coming into contact with air.

At this time, the sheet-like base material 1 is given a compressive force in the thickness direction by the squeezing rolls 9, 9, which means that it is squeezed, so that the low-viscosity liquid 2a impregnated therein is squeezed out from the sheet-like base material 1. It will be done. Therefore, together with the fact that the space between the two ridge reservoirs 2 and 3 is shielded and sealed by the squeezing rolls 9, 9, the low viscosity liquid 2a hardly enters into the varnish reservoir 3.
Loss of the low viscosity liquid 2a and dilution of the varnish 3a are prevented as much as possible.

The sheet-like substrate 1 brought into the varnish reservoir 3 passes through the varnish 3a, during which it is impregnated with the varnish 3a.

At this time, the fiber bundle 1a opened by the compression action of the squeezing rolls 9, 9 is re-formed by the decompressing action of passing through the squeezing rolls 9°9, so that impregnation with the varnish 3a can be carried out quickly. You will be raped. In addition, the low viscosity liquid 2a can be used in a state where the sheet-like base material 1 does not come into contact with air.
The varnish 3 is transferred from the inside to the inside of the varnish 3a and subjected to the squeezing action by the squeezing rolls 9, 9.
Since the sheet-like base material 1 brought into the fiber bundle 1a does not contain air, the varnish 3a is sufficiently impregnated into the inside of the fiber bundle 1a.

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

For example, as shown in FIG. 3, low viscosity liquids 2a with different viscosities
, 2'a may be provided so that the viscosity of the low viscosity liquid impregnated into the sheet-like base material 1 gradually increases.

Alternatively, as shown in FIG. 4, each of the storage tanks 2 and 3 may be an independent tank, and the two ridged storage tanks 2 and 3 may be connected to each other by a cylindrical base material passageway 7.

Furthermore, in cases where a low resin content of the sheet-like base material 1 is required, the squeeze roll 9.9 may not be provided and the base material passageway 7 may be configured to have a slit nozzle structure.

〔Effect of the invention〕

As can be easily understood from the above explanation, according to the present invention, a sheet-like base material can be impregnated with varnish evenly and in a sufficiently short time, and moreover, there are no air bubbles in the sheet-like base material. can do. This effect is significant when impregnating high viscosity varnishes.

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

Further, according to the present invention, since a timing roll or the like is not required, the device structure can be significantly downsized.

Simplification can be achieved.

Furthermore, if a squeezing action is applied to the sheet-like base material at the transition stage from the low-viscosity liquid to the varnish,
Loss of the low viscosity liquid and dilution of the varnish can be effectively prevented, and the impregnation action can be further promoted. Moreover, the amount of low viscosity liquid used in the sheet-like base material is extremely small.
The exhaust volume of the drying furnace in the drying process after varnish impregnation can be significantly reduced.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing an embodiment of the varnish impregnation device according to the present invention, and FIGS. 3 is a sectional view of an apparatus showing another embodiment, FIG. 4 is a sectional view of a main part of the apparatus showing still another embodiment, and FIG. 5 is a sectional view showing a conventional technique. DESCRIPTION OF SYMBOLS 1... Sheet-like base material, 2, 2'... Low viscosity liquid storage tank, 2a, 2'a... Low viscosity liquid, 3... Varnish storage tank, 3a... Varnish, 4. ...Guide mechanism, 5...Aperture mechanism, 7...Base material passageway. Figure 2 (A) (B) Figure 4

Claims (4)

[Claims] (1) A sheet-like base material made of fibrous material is passed through a low viscosity liquid such as a solvent, and then without being exposed to air.
A varnish impregnation method characterized by passing the varnish through the varnish. (2) The sheet-like base material is compressed during the transition from the low-viscosity liquid to the varnish.
The varnish impregnation method according to claim 1. (3) a low viscosity liquid storage tank storing a low viscosity liquid such as a solvent;
A varnish storage tank storing varnish, a base material passageway that communicates and connects both reservoirs below the surface of the stored liquid, and a sheet-like base material made of a fibrous material, a low viscosity storage tank, a base material passageway,
A varnish impregnation device characterized by comprising a guide mechanism that guides the varnish storage tank to pass through the varnish storage tank sequentially, and a squeezing mechanism that applies compressive force in the thickness direction to the sheet-like base material passing through the base material passageway. . (4) The squeezing mechanism is configured such that a pair of squeezing rolls are arranged facing each other in the base material passing path, and the sheet-like base material is passed through the base material passing path under pressure while shielding and sealing between both storage tanks. The varnish impregnation device according to claim 3, characterized in that: