JPH0382510A - Continuous manufacture of laminated sheet - Google Patents

Abstract

PURPOSE:To eliminate a hardening process that may be required for the title sheet after the cutting of the same by a method wherein resin liquid-impregnated base materials plurally superposed are pressed under heating at a specified temperature; a direction in which the base materials advance is then reversed at the exit part of a double-belt press; the base materials are subsequently heated, under ordinary pressure, at a temperature higher than the hating temperature at the time of the initial pressing and heating; and the hardening of the resin liquid among the base materials is substantially completed. CONSTITUTION:In the continuous manufacture of a laminated sheet, wherein a plurality of base materials impregnated with a thermosetting resin liquid which substantially does not generate reaction by-product such as gas and liquid in the process of hardening reaction are made into one body by superposing and heating to harden the resin liquid, the resin liquid-impregnated base materials plurally superposed are pressed under heating at a temperature of not lower than 120 deg.C by using a double-belt press 3 whose constitution comprises an endless belt having a substantially uniform pressure over the entire area of a press zone, and further, a direction in which the base materials advance is reverse at the exit part of the double-belt press, whereby said base materials are subsequently heated, under ordinary pressure, at a temperature higher than the heating temperature at the time of the initial pressing and heating, thus substantially completing the hardening of the resin liquid among the base materials.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for continuously manufacturing laminated boards suitable for various electrical insulating boards and printed wiring boards.

"Conventional technology" A long base material such as kraft paper is impregnated with a thermosetting resin liquid, multiple sheets of this impregnated base material are stacked, and the resin liquid is cured by applying pressure or heating without applying pressure. It has been conventional practice to continuously manufacture laminates.

However, since it usually takes about 1 to several hours for the thermosetting resin liquid to substantially complete curing,
Conventionally, in order to avoid increasing the length of the curing equipment, the laminate is cured to a specified degree of hardening by continuous curing in a short period of time, and then the laminate is cut to the required size, and then the process is carried out either batchwise in a post-curing furnace or in a long continuous furnace. Heat treatment is performed until curing is substantially completed.

"Problems to be Solved by the Invention" However, in the method for manufacturing a laminate, the continuous curing of the laminate formed by stacking the base materials impregnated with a thermosetting resin liquid is temporarily interrupted, and post-curing is performed using a separate device. Therefore, there are disadvantages such as interruption of continuous processes, complicating the manufacturing process, and increasing equipment costs.

This invention has been made to solve the above-mentioned disadvantages, and is an economical continuous production of laminates that substantially completes the curing of the thermosetting resin liquid during continuous curing in a short period of time and eliminates the need for a curing process after cutting. The purpose is to provide a method.

"Means for Solving the Problems" It is known that the curing time of thermosetting resins can be shortened by increasing the curing temperature. However, after impregnating a long base material with a thermosetting resin liquid, stacking multiple sheets of this impregnated base material and laminating metal foil such as copper foil if necessary,
When manufacturing laminates continuously by heating and curing the resin liquid, if the curing temperature is suddenly raised to 120°C or higher, thermal stress due to sudden dimensional changes in the impregnated base material or metal foil, and damage to the resin liquid. Due to the volatilization of components that do not volatilize at relatively low temperatures, such as crosslinkable vinyl monomers contained in
There is a problem that blistering occurs, and this tendency is particularly noticeable when curing without pressure.

The present inventors used a double belt press equipped with an endless belt that exerts substantially uniform pressure over the entire pressure zone, and by pressurizing and heating molding a resin liquid-impregnated base material, the curing temperature was Even if the temperature is raised to 120°C or higher, a laminate without the above-mentioned defects can be obtained continuously.Furthermore, by bending the base material at the exit part of the double belt press and reversing its direction of movement, the distortion is small and the required installation time is reduced. It was discovered that the area can be halved, leading to the present invention.

That is, in the method for manufacturing a laminate according to claim 1 of the present invention, a long base material essentially does not require a drying step, and substantially eliminates reaction by-products such as gas and liquid during the curing reaction process. In the continuous production method of laminates, the entire area of the pressure zone is impregnated with a thermosetting resin liquid that does not generate heat, and multiple sheets of the resin liquid-impregnated base material are piled up and heated to cure the resin liquid and integrate them. Using a double belt press configured with an endless belt that applies substantially uniform pressure over the entire length, the resin liquid-impregnated base material formed by stacking the plurality of sheets is heated under pressure at a temperature of 120 ° C. or higher. , further reversing the traveling direction of the base material at the double belt press exit section,
Subsequently, the substrate is heated under normal pressure at a temperature equal to or higher than the heating temperature in the pressure heating to substantially complete curing of the resin liquid in the substrate.

Further, in the method for manufacturing a laminate according to claim 6, the double belt press is used to press and heat a laminate formed by overlapping a metal foil and a plurality of resin liquid-impregnated substrates at a temperature of 120° C. or higher. Then, the traveling direction of the base material is reversed at the exit part of the double belt press, and then the base material is heated under normal pressure at a temperature higher than the heating temperature in the pressure heating to remove the resin liquid in the base material. The solution to the above problem is to continuously correct the warpage of the laminate after substantially completing the curing and subsequently cooling the laminate.

The manufacturing method of the present invention will be explained in detail below.

First, a plurality of long base materials are prepared. Here, examples of the long base material include glass fiber-based materials such as long glass fiber cloth and glass nonwoven fabric, paper mainly composed of cellulose fibers such as kraft paper, aluminum hydroxide mixed paper, and linter paper;
Examples include sheet-like or band-like materials made of inorganic fibers such as asbestos cloth.

When using paper as a long base material, from the viewpoint of impregnability and quality, the density when air-dried (bulk density) is 0.3 to 0.79.
/co paper mainly composed of cellulose fibers, such as kraft paper, is preferred. When impregnating these base materials with the resin liquid, it is preferable to previously perform an impregnation drying treatment on the base materials using a treatment agent such as methylol melamine, methylol phenol, methylol guanamine, or N-methylol compound. That is, such treatment improves the water resistance of the base material and reduces its hygroscopicity, thereby improving the electrical properties of the resulting product.

In this case, the amount of the treatment agent deposited is usually about 5 to 35 parts by weight based on looM parts of the base material.

In addition, the thermosetting resin liquid referred to in the present invention that essentially does not require a drying process and does not substantially generate reaction by-products such as gas or liquid during the curing reaction process is a conventionally known unsaturated polyester resin. refers to thermosetting resins that are liquid at room temperature, such as allyl resins, allyl resins, vinyl ester resins, and epoxy acrylate resins.These resins have unsaturated groups in their molecules, and there are It is a resin that has the characteristic of being crosslinked via a vinyl monomer, and such resins also include epoxy resins.

These thermosetting resins are in a liquid state with low viscosity when impregnated into the base material, harden after being impregnated into the base material, and bond well with the base material, and are suitable for the method of the present invention. .

In addition, if necessary, a halogen-containing flame retardant imparting component and a flame retardant aid such as phosphoric acid ester, antimony trioxide, or aluminum hydroxide may be added to the thermosetting resin liquid used for impregnating the base material. You can also use it.

In addition, when using any thermosetting resin liquid, the viscosity of the resin liquid can be adjusted appropriately depending on the purpose of use of the laminate to be manufactured, the pressure during pressure molding, etc., but usually 256C 50 poise or less is suitable. That is, if it exceeds 50 poise, impregnation into the base material becomes poor and air bubbles tend to remain in the resulting laminate, which is not preferable.

Next, the elongated base material is impregnated with such a thermosetting resin liquid by a known method such as a coating method or a dipping method. The amount of impregnated thermosetting resin liquid is related to the pressure applied by the double belt press, which will be described later. and adjusted so that the resulting laminate is substantially free of air bubbles, and the amount of resin liquid discharged from the base laminate when pressurized by a double belt press is 10% or less of the amount of cured resin in the product laminate; It is desirable to adjust the amount to preferably 5% or less.

Next, a plurality of base materials impregnated with the resin liquid are laminated and subjected to pressure and heat curing treatment using a double belt press that applies substantially uniform pressure over the entire pressure zone. Here, as a double belt press having substantially uniform pressure over the entire pressure zone according to the present invention, stainless steel endless belts each having a thickness of about one shoulder are installed above and below, and there is a gap between these upper and lower endless belts. The resin liquid-impregnated base material laminated on the endless belt is sandwiched between the base materials and can be pressurized and heated while being fed out, and has a structure such that the pressure of the pressure band between the endless belts is substantially equal. be.

To give a more detailed example of such a double belt press, ■ A plurality of rows of roll pairs are arranged to sandwich the upper and lower belts and apply pressure to the belts, and the roll diameter is 5Qgx or less and the roll pitch and roll diameter are The ratio is 1.
A system that reduces the pressure drop between adjacent rolls by keeping it below 2. In this case, the roll may be of a fixed type, or it may be of a type that is placed between a pressure plate provided above and below the endless belt and the roll revolves around the pressure plate. It should be noted that if the diameter of the rolls becomes large and the distance between the rolls is too large, large waves will occur in the pressure applied to the base material, which is undesirable.

■ A type in which the upper and lower endless belts are sandwiched, a pressure plate is placed to apply pressure to the belts, and a pressure medium is press-fitted and circulated between the pressure plate and the endless belt for the purpose of lubrication.

■ A container for storing pressure medium is provided between the upper and lower endless belts, and the opening of this container is configured to be in contact with the endless belt, so that the endless belt is directly pressed by the pressure medium.

etc., and the pressure medium storage type is particularly suitable because the pressure difference across the entire pressure zone is small.

In such a double belt press, regardless of the system, the presence of large pressure distribution, especially the presence of large pulsating pressure in the direction of movement of the base material, is undesirable. In other words, in the high-temperature curing of the present invention, large fluctuations in pressure distribution should be avoided because warping of the obtained laminate, waving phenomenon, wrinkles of metal foil, etc. are likely to occur.For example, large fluctuations in pressure distribution should be avoided. 20% or less and ±2
It is desirable that it is less than Kg/c-.

The pressure applied during processing in such a double belt press is adjusted appropriately to control the content of the base material in the laminate to be produced, and also varies depending on the type of base material and resin liquid used, but /cra2G to 10
It is approximately 0 K g/cta"G, preferably 10
K g/cg+”G to 50 K g/cta”
It is considered to be G. This, the pressure is 5 Kg/cm"G.
If the temperature is lower, abnormal molding such as waving, delamination, and blistering of the metal foil is likely to occur in the resulting laminate, and abnormal molding may occur especially when a curable resin liquid with a high content of crosslinking vinyl monomer is used. The occurrence of this problem becomes significant, and the resulting laminate has a small amount of base material at, resulting in a laminate with low strength. On the other hand, when the pressure exceeds 10 Q K g/c@'G,
Not only is it unnecessary for maintaining formability, but the base material content in the resulting laminate becomes too large, and conversely it tends to cause delamination and a decrease in strength.

The temperature and time applied during processing in double belt presses vary depending on the type of thermosetting resin liquid used, the type of curing catalyst, etc., but the temperature is 120°C.
above is necessary, and the upper limit is usually about 200°C. In other words, if the temperature is less than 120°C, the time required for curing will be too long, making it difficult to achieve the objective of the present invention, which is to shorten the curing time. This is because foaming or delamination due to distortion or evaporation of the crosslinkable vinyl monomer is likely to occur. In addition, in pressure heating using a double belt press, the elastic recovery of the base material does not occur in the laminate obtained by curing and integrating when the pressure is released, and it is sufficient to withstand continuous conveyance in the next pressureless heating process described later. It is necessary that the curing of the curable resin liquid is progressing, therefore, the appropriate pressure and heating time is 0.5 minutes or more and 10 minutes or less.

In such pressure heating using a double belt press, a laminate made of a base material impregnated with a thermosetting resin liquid, or a laminate made of a metal foil such as copper foil laminated thereon, is used as a steel belt. Since it is restrained by an endless belt, the base material impregnated with the resin liquid reaches a predetermined temperature in a short time due to direct heat conduction from the belt.

Therefore, the substrate can be heated to the desired temperature in an extremely short heating time compared to other types of heating furnaces that heat by blowing hot air or by heat radiation. Deformation due to dimensional changes in the foil (copper foil) and curing shrinkage of the thermosetting resin liquid is further restrained by the belt, and is prevented, and volatilization of crosslinkable vinyl monomers, etc. in the resin liquid caused by increases in heating temperature is further prevented. It is suppressed because it is in a pressure state. As a result, even if the curing temperature is increased, warping of the laminate, waving and delamination, and wrinkling and blistering of the metal foil are prevented, and curing at high temperatures and in a short time becomes possible.

After that, the laminate is heated under pressure using a double belt press.
The direction of travel is reversed at the exit of the double belt press, and heating is continued under normal pressure to substantially complete curing of the curable resin. The reversing method is as shown in Fig. 1, a method of paralleling the drum 8b of a double belt press, a method of reversing the
As shown in the figure, a guide roll 16 installed separately...
There is a way to reverse it by There is also a method of pulling the device downwards in terms of device placement. Here, the heating temperature under normal pressure is equal to or higher than the heating temperature under pressure using a double belt press using normal light, and is set to 200° C. or lower.

This is because if the heating temperature is lower than the heating temperature under pressure, it will take a long time to substantially complete the curing, not only will the heating furnace become long, but there is also a risk that the curing will not proceed.
This is because heating at a temperature higher than °C may cause discoloration or significant warping of the laminate or metal foil.

The heating time under normal pressure is appropriately adjusted depending on the degree of curing of the thermosetting resin liquid in the base material after pressure heating, but is usually about 5 minutes or more and 1 hour or less. If the heating time is less than 5 minutes, curing will not be substantially completed and, for example, when the obtained laminate is processed into a wiring board, there is a risk of deformation during use, which is not preferable. Further, it is unnecessary to heat for more than one hour, and in this case, the heating furnace becomes long, which is not preferable.

The laminate that has been substantially cured by heating under normal pressure is cut into a rectangular shape with predetermined dimensions using a cutter such as a guillotine cutter, and then straightened if necessary.
The end face is processed and the product is made. In this case, the warpage correction and the end face treatment in the longitudinal direction can also be performed continuously following the heat treatment before cutting with a cutter.

In particular, in the case of single-sided metal foil-covered laminates, the laminate warps significantly at room temperature due to curing shrinkage of the curable resin liquid and the difference in coefficient of linear expansion between the metal foil and the cured resin containing the base material. Therefore, it is often necessary to straighten the warp, and after cooling the single-sided metal foil clad laminate that has been substantially completely cured by heating under normal pressure to a predetermined temperature, it is continuously straightened using a warp straightening machine such as a roll. It is desirable to straighten the warp and then cut it.

Here, the temperature of the laminate during warp correction is preferably close to room temperature, and is usually about 50° C. or lower, although it varies depending on the type of base material and thermosetting resin liquid used.

Although the laminates obtained in this way vary depending on the type of base material and thermosetting resin used, pressurization or heating conditions, etc., the base material content (weight % of the base material in the laminate) ) is about 30 to 80% by weight,
For example, if kraft paper is used as the base material, 35 to 6
Approximately 5% by weight is suitable. In other words, if the kraft paper content is less than 35% by weight, the resulting laminate will have low mechanical strength and bending rigidity, while if it exceeds 65% by weight, it will not only tend to cause delamination, but also have poor punchability and moisture resistance. This is because it causes a decrease in sexual performance, which is undesirable.

In addition, in order to produce a metal foil-clad laminate, a metal foil is layered on one or both sides of a laminate made of a resin acid-impregnated base material at the same time as the base material is overlaid, or after a slight delay.
This is done by supplying it to a double belt press. As the metal foil used here, an electrolytic copper foil intended for use in printed circuit boards is suitable from the viewpoint of corrosion resistance, etching property, and adhesiveness, but aluminum foil or the like may also be used. Further, such metal foil usually has a thickness of about 10 to 100 microns, and preferably has its adhesive surface roughened to improve adhesiveness.

An adhesive is preferably used for bonding the metal foil and the resin-impregnated base material. As the adhesive, it is preferable to use a liquid or semi-fluid adhesive that does not generate unnecessary acid by-products during the curing process, that is, an adhesive that preferably has a viscosity of 5000 bouise or less.

From this point of view, for example, epoxy-acrylate adhesives, epoxy/resin adhesives, polyisocyanate adhesives, or various modified adhesives thereof are suitable. As the epoxy adhesive, a mixture of a bisphenol A type epoxy resin and a curing agent such as a polyamide resin or amines is suitable.

By introducing such an adhesive, it is possible to produce a metal foil-clad laminate that has excellent adhesive strength of metal foil, and also has excellent solder heat resistance and electrical insulation properties.

When the adhesive is used after being applied to metal foil, it may be precured to a semi-cured state by heat treatment at 60 to 150'C for 2 to 7 minutes after application. Furthermore, the adhesive can be applied simultaneously during lamination. The thickness of the adhesive coating may be about 10 to 100 μl, and preferably 20 to 50 μl.

The thickness of the laminate obtained by the present invention varies depending on the type of substrate, the composition of the thermosetting resin liquid, the use of the laminate, etc., but is usually 0.5 to 3. OMR is preferred.

"Examples" The present invention will now be described in more detail with reference to Examples.

FIG. 1 is a diagram showing an example of an apparatus suitably used to carry out the method of the present invention. This equipment consists of a roll for feeding out the base material A, an impregnation tank 2 for impregnating the base material A with the thermosetting resin liquid B, and a double belt press 3 for performing pressure heat treatment. A heating furnace 4 for performing heat treatment under pressure, a roll 5 for feeding out the metal foil C, a coating machine 6 for applying adhesive to the metal foil C, and a heating furnace 7 for preheating the adhesive. It is configured with the following. The double belt press 3 is of a pressure medium storage type, and includes drums 8 a, 8 a, 8 b, 8 b, an endless belt 9, 9 wound between colleranos, and a pressurizing chamber 10.
The pressurizing chamber IO is generally configured to include a pressure medium 11 made of a high-temperature fluid and filled in the pressurizing chamber IO.

In order to manufacture a laminate by carrying out the method of the present invention using such an apparatus, a plurality of base materials A...
are simultaneously fed out from the roll and impregnated layers 2 and 2.
After being impregnated with the thermosetting resin liquid B, the base materials A, etc. are transferred between the endless belts 9 and 9 of the double belt press 3 in a stacked state. At the same time, a metal foil C made of copper foil or the like is unwound from the roll 5, coated with adhesive by a coating machine 6, and then preheated in a heating furnace 7 to form the outermost layer. 9. While overlapping the base material A... with the endless belt 9.
Transfer between 9 and 9 days. Then, using a double belt press 3, a plurality of base materials A impregnated with thermosetting resin liquid B and metal foil C are
After heating under pressure to primarily cure the resin liquid, the traveling direction of the base material A is reversed at the double belt press outlet 3a, and then heated under normal pressure in the heating furnace 4 to substantially cure the resin liquid. After completion of curing, the laminate is further cooled in a cooling chamber 12 to form a laminate. Here, the laminate of the base materials A... is reversed at the double belt press exit section 3a by advancing the laminate along the drum 8b of the double belt press 3.

Thereafter, the laminate is successively passed through a long-axis straightening roll 13 and a short-axis straightening roll 14 to correct warpage in both the long-axis and short-axis directions of the laminate,
Further, it is continuously cut using a guillotine cutter 15 to obtain a single-sided metal foil-clad product having a predetermined size.

In addition, although the above example shows an example in which one side is coated with metal foil, it is also possible to produce a laminate without metal foil affixed using the above apparatus, and in that case, a laminate plate impregnated with thermosetting resin B can be used. Only the base material A... is transferred between the endless belts 9 and 9 of the double belt press 3 in a superimposed state.

In the above example, MHA...
This was carried out by placing the laminate along the drum 8b of the double belt press 3, but in addition, as shown in FIG. The stacked body may be reversed by disposing guide rolls 16 along the line and passing between these guide rolls 16.

"Effects of the Invention" As explained above, the method for continuously manufacturing a laminate of the invention according to claim 1 of the present invention essentially does not require a drying process and a curing reaction process is performed on a long base material. impregnated with a thermosetting resin liquid that does not substantially generate reaction byproducts such as gas or liquid, and then stack and heat multiple sheets impregnated with the resin liquid to harden the resin liquid and integrate them. In a method for continuously manufacturing a laminate, a double belt press comprising an endless belt having substantially uniform pressure over the entire pressure band is used to impregnate the plurality of laminated sheets with resin liquid. Pressure and heat the base material at a temperature of 120°C or higher,
The traveling direction of the base material is reversed at the double belt exit portion, and then the base material is heated under normal pressure at a temperature higher than the heating temperature in the pressure heating to substantially complete curing of the resin liquid in the base material. Therefore, there is no need to perform post-hardening treatment after cutting as in the past, and the entire hardening process can be done in a short time, so the equipment does not become large and the required installation area is small, thus reducing manufacturing costs and equipment. The laminate can be manufactured economically without increasing costs.

Further, the method of the invention according to claim 6 includes using the double belt press to press and heat a laminate formed by overlapping a metal foil and a plurality of resin liquid impregnated base materials at a temperature of 120° C. or higher, Furthermore, the traveling direction of the base material is reversed at the double belt exit portion, and then the base material is heated in the pressure heating step 7! ! The laminate is heated under normal pressure at a temperature of 100°C or higher to substantially complete curing of the resin liquid in the base material, and then the laminate is subsequently cooled, and then the warpage of the laminate is continuously corrected. Therefore, there is no need to perform post-hardening treatment after cutting, and the entire hardening process can be performed in a short time.Moreover, even though the metal foil is attached, there is no need for warping of the laminate, waving, delamination, or wrinkles of the metal foil. This makes it possible to prevent sagging.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining the present invention in detail. FIG. 2 is a diagram showing a modification of the apparatus shown in FIG. 1. A: Base material, B: Thermosetting resin liquid,
C...Metal foil, D...Product, 3...
...Double belt press, 3a...Double belt press outlet, 4...
... Heating furnace, 9 ... Endless belt, IO
...... Pressurized chamber, II... Pressure medium, 12
・・・・・・Cooling room.

Claims (6)

[Claims] (1) Essentially no drying process is required for long base materials;
and is impregnated with a thermosetting resin liquid that does not substantially generate reaction by-products such as gas or liquid during the curing reaction process, and a plurality of substrates impregnated with the resin liquid are stacked and heated to cure the resin liquid. In a method for continuous production of laminates in which the plurality of sheets are stacked together using a double belt press configured with an endless belt that applies substantially uniform pressure over the entire pressure zone, 12 resin liquid impregnated base materials
Pressure and heat at a temperature of 0° C. or higher, further reverse the traveling direction of the base material at the exit portion of the double belt press, and then heat the base material at a temperature higher than the heating temperature in the pressure and heat under normal pressure. A method for continuously manufacturing a laminate, characterized in that curing of the resin liquid in the base material is substantially completed. (2) In the method for continuously manufacturing a laminate according to claim 1,
A method for continuously manufacturing a laminate, characterized in that the laminate is a metal foil-clad laminate formed by laminating a plurality of base materials impregnated with a resin liquid and metal foil simultaneously or in a separate process. (3) In the method for continuously manufacturing a laminate according to claim 1,
A double belt press configured with an endless belt having a substantially uniform pressure over the entire pressure zone, having a pressure chamber having the endless belt as one constituent surface,
A continuous manufacturing method for laminated plates, characterized in that it is a double belt press using a fluid as a pressure medium. (4) In the method for continuously manufacturing a laminate according to claim 1,
The pressure in the pressure heating process is 5 to 100Kg/cm^
A method for continuously manufacturing a laminate, characterized in that the range is 2G. (5) In the method for continuously manufacturing a laminate according to claim 1,
A method for continuously manufacturing a laminate, characterized in that the base material is paper. (6) Essentially no drying process is required for long base materials;
The resin is impregnated with a thermosetting resin liquid that does not substantially generate reaction by-products such as gas or liquid during the curing reaction process, and the metal foil and a plurality of substrates impregnated with the resin liquid are overlapped and heated. A continuous manufacturing method for single-sided metal foil-clad laminates in which liquids are cured and integrated, using a double belt press that is equipped with an endless belt that applies substantially uniform pressure over the entire pressure zone. , heating a laminate in which the metal foil and a plurality of base materials impregnated with a resin liquid are laminated together under pressure at a temperature of 120° C. or higher, and further reversing the traveling direction of the base materials at the exit portion of the double belt press; Subsequently, the base material is heated under normal pressure at a temperature higher than the heating temperature in the pressure heating to substantially complete curing of the resin liquid in the base material, and then the laminate is cooled, and then continuously heated. A method for continuously producing a laminate, comprising: correcting warpage of the laminate.