JPS6042566B2 - Method for continuously manufacturing electrical laminated insulation boards or metal foil clad laminates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for manufacturing electrical laminates or metal foil laminates.

Conventionally, laminated insulating boards for electrical or electronic parts, or metal foil-clad laminates for printed circuit boards have been manufactured mainly using phenolic resin and paper as base materials.

This conventional product impregnates paper with a resin varnish made liquid at room temperature by using a solvent, then dries the solvent to form a so-called B stage, which forms a prepreg that does not have adhesiveness at room temperature, and then cuts and laminates the paper. Manufactured using a heated and pressurized press. The reality is that the productivity and product cost of such conventional methods have reached their limits in recent years, and new manufacturing methods with higher productivity are expected. Some conventional products are based on epoxy resin and paper, but this also follows the above conventional method, and also uses a resin varnish made of unsaturated polyester, which is solid at room temperature, and a solvent. Although some proposals have been made to use this method, this method is also based on the above-mentioned conventional method and has not been put into practical use due to the high cost.

Furthermore, Japanese Patent Laid-Open No. 103/1983 discloses a type of continuous manufacturing method for printed circuit boards. In this method, a composite of a resin liquid-impregnated base material and a coating is pulled out through a die having an opening that becomes narrower in the direction of travel, and at the same time the composite passing through the die is heated to form and harden. However, since the composite is pultruded and molded by overcoming the resistance when the composite passes through the inside of the die, the base material must be able to withstand the large tension required for this purpose.
For example, it is limited to glass cloth. In addition, because the composite is strongly pulled in a single direction during molding, the product laminate becomes directional, making it ideal for electrical applications such as printed circuit boards and insulating boards that require extremely high homogeneity. It is not suitable for industrial laminates, so it has not yet been put into practical use industrially. In view of the current situation, the inventors of the present invention conducted intensive research and found that the crosslinking monomer, for example, styrene, is a liquid unsaturated polyester resin that is liquid at room temperature, and is directly impregnated into the base material without using any solvent. , stack them as is,
It was discovered that electrical insulating plates or metal foil-clad laminates with excellent properties could be efficiently produced by subsequent curing, and the present invention was achieved.

The present invention is applied to a plurality of substrates to which an unsaturated polyester resin solution containing a crosslinking vinyl monomer and which is liquid at room temperature and can be cured without producing volatile by-products is continuously supplied in parallel. The impregnated base materials are continuously impregnated individually, the impregnated base materials are continuously laminated, both sides of the laminate are continuously coated with a film air barrier and/or metal foil, and the laminate is continuously impregnated in this state. The gist of the present invention is a method for continuously manufacturing an electrical laminated insulating plate or a metal foil-clad laminated plate, which is characterized by being cured to a state where it can be cut at least under substantially no pressure.

FIG. 1 is a process explanatory diagram showing a typical embodiment of the present invention.

N sheets of long cellulose fiber paper 10-1 to 10-n unwound from n reels 1-1 to 1-n are dried by passing through a dryer 2 as necessary.

The excess adsorbed water contained in the paper will reduce the high heat resistance required for electrical laminated insulating boards and metal foil laminates, such as 26
Under conditions such as 0°C x 6x2 or 200°C x 3x, ``swelling'' often occurs, which is undesirable. It is preferable that paper stored in the atmosphere be dried under dry conditions such as 110°C x 1 powder, and must be dried under conditions that do not cause blistering.
The resin liquid 1 is separated into sheets by the resin liquid supply device 5.
1 is impregnated from one side.

Here, in order to achieve good impregnation and impregnation speed, it is important to appropriately select the viscosity of the resin liquid and the density of the paper. In general, the lower the viscosity of the resin liquid, the higher the impregnating property, and the viscosity can be lowered by increasing the proportion of liquid monomer in the resin liquid or decreasing the molecular weight of the unsaturated polyester chain, but it is important to avoid lowering the viscosity more than necessary. In the invention, it is undesirable because it impairs the heat resistance and mechanical properties of the resulting product. Using paper with a low density also improves impregnability, but lowering the density more than necessary impedes the product's expandability and processability. In the present invention, desirable results are obtained when the viscosity of the resin liquid at 25 DEG C. is 0.5 to 15 poise and the paper density is 0.3 to 0.7 g/d.

More preferably, the viscosity of the resin liquid is 1 to 10 poise,
Paper density is 0.4-0.6g/c! It is i. In addition, in the present invention, it is important to impregnate the paper with the resin liquid from one side, and it is difficult to ensure a good impregnated state using ordinary methods such as dipping the paper in the resin liquid. be.

In the method of the present invention, in which the impregnated base material is continuously laid up while the impregnated resin is still in a liquid state, and then continuously cured under virtually no pressure, first of all, the resin liquid is applied internally to the base material. The main premise is that the base material is sufficiently impregnated with the resin liquid, and if there are any areas in the base material that are not impregnated with the resin liquid or where air bubbles are formed, it will adversely affect the electrical and mechanical properties of the product.

For this reason, it goes without saying that careful attention should be paid to the apparent density of the substrate, the viscosity of the resin liquid, the impregnation method, etc., but it is difficult to obtain a sufficient impregnation effect if the substrates are piled up and impregnated at the same time, so it is important to impregnate each sheet one by one. , preferably before laminating the impregnated base material,
The substrates are preferably conveyed independently for as long as possible and then laminated. The unsaturated polyester chains used in the present invention include, for example, unsaturated dibasic acids such as maleic acid, maleic anhydride, and fumaric acid; saturated dibasic acids such as succinic acid, adipic acid, phthalic anhydride, isophthalic acid, and terephthalic acid; It is synthesized using glycols such as ethylene glycol, diethylene glycol, and propylene glycol as raw materials.

In the present invention, the vinyl monomer for crosslinking is preferably liquid, and styrene is most suitable for the continuous production method of the present invention in terms of curing speed, product homogeneity, and product cost.

Vinyltoluene, diallyl phthalate, and vinyl acetate also show good results if some inconveniences are eliminated. Such an unsaturated polyester resin liquid is liquid at room temperature, and does not produce volatile byproducts such as water or carbon dioxide upon curing.

Furthermore, as is generally accepted, there are resins that undergo three-dimensional crosslinking during the curing reaction and harden to an insoluble and infusible state. This does not necessarily mean that heat is required for curing, but rather that resins that harden at room temperature. It also includes light- or radiation-curable resins. The resin-impregnated paper 14 is continuously laminated by the clearance provided between the roll 6 and, for example, the blade-like material 7, and at the same time, the film-like material unwound from the reels 3 and 4 is laminated.

Here, the above clearance is the thickness of the product! substantively determines the Therefore, in response to this clearance,
The thickness of the paper to be used and the number of sheets of resin-impregnated paper to be laminated are set. In the present invention, for example, 0.25Tr
By using paper with a thickness of $L, the thickness is approximately 0.2
5? By sequentially increasing the number of sheets of paper, the thickness can be determined by increasing the number of sheets. It is possible to easily manufacture products that are Furthermore, in the production of laminated insulating plates, the film-like materials 12 and 13 to be laminated as air barriers are preferably films having surface smoothness, such as cellophane or polyester films, from the viewpoint of product performance. If necessary, especially when using cellophane, it is desirable to dry it before laminating. In the present invention, after laminating the impregnated paper and the film-like material or metal foil, a blade-like material may be used to squeeze out the excess resin impregnated onto the paper and at the same time eliminate air bubbles in the resin. Depending on the situation, a roll-shaped material may be used, or both may be used in combination.

Curing is performed, for example, in a heating furnace 8.

It is preferable that the heating furnace 8 is always heated to 50°C to 100°C. Curing conditions vary depending on the type and amount of the catalyst and auxiliary agent used, and the type and amount must be set in consideration of the pot life of the resin liquid and the properties of the product. Too low a curing temperature will sacrifice the pot life of the resin solution, while too high a temperature will promote the generation of bubbles due to vaporization of the vinyl monomer, a decrease in crosslinking density, and oxidation of the vinyl monomer.
In the present invention, among the many organic peroxides, in particular,
0.5 to 3 parts of cumene hydroperoxide or t-butylperoxy-2-ethylhexanoate and 0.005 parts of auxiliary agent such as cobalt naphthenate.
When ~0.02 part is blended and the curing time is 1 to 9 times at the above curing temperature, an electrical laminated insulating board or a copper-clad board with excellent properties can be obtained. The state of curing has a large effect on the properties of the product.

In the present invention, it is important to control the degree of unsaturation of the unsaturated polyester chain in advance using saturated dibasic acids, and the hardness of the resin alone is 9 on the Rockwell hardness scale.
It is preferable to use one having a molecular weight of 0 to 120, especially in view of the mechanical properties and processing properties of the product. Phthalic acid is common as the saturated dibasic acid, but isophthalic acid and terephthalic acid are more preferred in the present invention. The cured laminate 17 is continuously taken off by a take-off machine 9.

Although curing may be completed at this stage, it is at least in a cuttable state, that is, it does not deform when cut, and the metal foil does not move even slightly and cause wrinkles, that is, it has self-shape retention. After curing continuously to a state where the barrier can be peeled off and cut, it may be after-cured for a suitable period of time, for example, for the purpose of reducing the odor of the crosslinking vinyl monomer. Also,
The thickness accuracy can be finely adjusted by adjusting the clearance of the roll-shaped material 15 installed in the heating furnace. After continuous curing, the film-like air barrier on both sides is continuously peeled off to obtain an electrical laminated insulating board. When a film-like air barrier is used on one side and a metal foil is used on the other surface, a single-sided metal foil-covered laminate is obtained by peeling off the film-like air barrier after curing. As shown in the figure, the laminate 16 is cured under substantially no pressure, except for a slight pressure due to the weight of the laminate, without being subjected to side pressure by a press or the like during the curing reaction.

Therefore, it is necessary that the resin liquid does not contain a solvent and is liquid at room temperature, and that it can be cured without producing volatile by-products. Unlike general-use corrugated boards, electrical laminated insulation boards and metal foil laminates can be heated to 1260°C or 200°C.
It is required to have advanced properties such as heat resistance at ℃, 2. low heat shrinkage, 3. high thickness accuracy, 4. surface smoothness, 5. low moisture absorption properties, 6. good punching workability, and 7. high electrical insulation properties.

We have discovered that it is possible to satisfy these characteristics by carefully implementing the manufacturing method described above, which was previously only possible using the pressurized press method. It's amazing if you think about it. The case where cellulose fiber paper is used as the base material has been described above, but by using, for example, glass fiber cloth as the base material, it is possible to create an electrical laminated insulating board or a metal foil-clad laminate made of glass cloth and unsaturated polyester resin. can be manufactured similarly.

Also in the present invention, all additives and the like that are normally mixed into laminates can be used. For example, flame retardants, flame retardant aids, fillers, colorants, etc. may be used as appropriate. The present invention will be explained in more detail with reference to Examples below. Example 1 An unsaturated polyester chain was synthesized using maleic acid, isophthalic acid, and ethylene glycol as raw materials, and styrene was blended to form an unsaturated polyester resin. To 100 parts of an unsaturated polyester resin, 2 parts of cumene hydroperoxide and 0 cobalt naphthenate were added. When 0.01 part was added and the resin was cured alone, the Rockwell hardness of the cast product was 106, and the flexural modulus was 283k9/n! An unsaturated polyester resin liquid having a viscosity of 5 poise at 25° C. was obtained.

This material has a density of 0.53 when air-dried under 65% RH.
g/Cjl and thickness 0.25? Yes, width is 500
One side of long cellulose fiber paper of gourd is impregnated, two sheets of resin-impregnated paper are laminated, and both sides are covered with cellophane.
After curing continuously at a line speed that allows 3-powder heating at a temperature of 70°C and continuously peeling off the cellophane,
After cutting every D71rm, after-curing with 6 pieces at 60°C, the thickness was 0.5mm. And it’s 50077!
77! A square laminated insulation board was obtained. This one is 1260
Blisters at ℃×w seconds or 200℃×3 times,
It has heat resistance with no abnormalities such as delamination, foaming, cracking, and discoloration, and the heat shrinkage rate at 2180°C for 10 minutes is 0.
3% or less, thickness accuracy of 331100, 4
It had excellent surface smoothness. In addition, the moisture absorption properties of the paper were actually 112 to 113 compared to the conventional paper-phenol product. 6. Punching workability: room temperature punching is possible, 7JI
The surface electrical resistance specified in S-C-6481 is 3 x 101
It had excellent properties such as 4Ω.

Example 2 In Example 1, six sheets of resin-impregnated paper are laminated, and the thickness is 1.6? A laminated insulating board was obtained.

This material showed good workability by heating punching at 50 DEG C. to 70 DEG C., and other properties were the same as in Example 1.

Example 3 In Example 2, cellophane was used on both sides of the air barrier film, but in Example 2, the bottom surface was not coated with an adhesive having a long thickness of 35) Pm. Electrolytic copper foil (Fukuda Metals CF-T3) is used to prevent peeling.
A copper-clad laminate for printed circuit boards having a thickness of 1.6 TfUTL was obtained.

The peel strength of copper specified in JIS-C-6481 was 1.1k9/Cln.

Although the peel strength was slightly inferior to that of the conventional paper-phenolic copper board, there was no problem in practical use. Unlike conventional methods, the resin is in a liquid state when the copper foil is laminated, so a delicate bond between the resin liquid and the surface of the copper foil is achieved, and no special adhesive is required as in conventional methods.

For this reason, it has excellent surface electrical resistance characteristics especially under wet conditions, and the surface electrical resistance during moisture absorption specified in JIS-C-6481 actually showed a value of 1013Ω or more. Example 4 In Example 3, electrolytic copper foil was continuously laminated on both sides to obtain a double-sided copper-clad laminate as an air barrier film.

The properties of this product were similar to those shown in Example 3. As described above, the present invention enables continuous production, which was impossible in conventional methods due to the necessity of a pressurizing process, to be achieved using typical non-containing resins that do not produce any volatile by-products during curing, unlike phenolic resins. This method makes efficient continuous production possible by cleverly applying unsaturated polyester resin liquid, which is a pressure molding resin, and is liquid at room temperature, and its industrial value is extremely high.

That is, since a press cannot be used in the continuous production method of rigid-type laminates, for example, if a phenolic resin is used that generates water as a byproduct during curing, a cavity will be created inside the resin, making it impossible to obtain a completely satisfactory product.

Unsaturated polyester resins are suitable for the purpose of the present invention because they generate volatile byproducts during curing and also have excellent electrical properties. Furthermore, if air bubbles remain inside the base material layer after co-immersion, they cannot be removed unlike compression molding, so substantially all the voids inside the base material layer must be filled with the resin liquid by co-immersion.

For this purpose, an individual one-sided impregnation method is suitable, in which a resin liquid is individually supplied to each base material and substantially all of the voids inside the base material layer are filled with the impregnating resin liquid. Furthermore, it is known that oxygen in the air acts as a polymerization inhibitor on unsaturated polyester resins.

Therefore, during curing, the uncured laminate must be shielded from contact with air. The metal foil of metal foil-clad laminates is also an air barrier, but in the case of single-sided metal foil-clad laminates and unclad laminates, the exposed surface of the resin-impregnated base material is used as a film-like air barrier. It needs to be coated with and peeled off after curing. Such a film-like air barrier also serves as a carrier sheet to prevent uncured resin liquid from adhering to and contaminating the curing device. The present invention, by combining at least these requirements,
This makes it possible to commercialize continuous industrial production of rigid-type electrical laminates and metal foil-clad laminates.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process explanatory diagram of one example of implementing the manufacturing method of the present invention.

2 is a dryer, 5 is a resin liquid supply device, 6 is a roll, 7 is a blade-like object, 8 is a heating furnace, 9 is a take-up machine, 10-1~
10-n is cellulose fiber paper, 11 is resin liquid, 12,1
3 is a film-like material, 14 is resin-impregnated paper, 15 is a roll,
16 is an uncured laminate, and 17 is a cured laminate.

Claims (1)

[Claims] 1. A plurality of sheets of unsaturated polyester resin containing a crosslinking vinyl monomer and which is liquid at room temperature and can be cured without producing volatile by-products are continuously supplied in parallel. Substrates are individually and continuously impregnated, the impregnated substrates are continuously laminated, both sides of the laminate are continuously coated with a film-like air barrier and/or metal foil, and in that state, the impregnated substrates are continuously impregnated. A method for continuously manufacturing an electrical laminated insulating board or a metal foil-clad laminate, comprising curing the laminate continuously under substantially no pressure to at least a state in which it can be cut. 2 Determining the thickness of the covering laminate by the clearance,
The method according to claim 1, wherein the method is transferred and cured under substantially no pressure. 3. The method according to claim 1 or 2, wherein both sides of the laminate are continuously coated with a film-like air barrier, and after continuous curing, the barrier is continuously peeled off. 4. Either one of claims 1 or 2, wherein one side of the coated laminate is the barrier and the other side is a metal foil, and after continuous curing, the barrier on one side is continuously peeled off. the method of. 5. The method according to claim 1 or 2, wherein both sides of the coated laminate are coated with metal foil, and after continuous curing, the coated laminate is intermittently cut into appropriate lengths. 6 The density of the base material when air-dried is 0.3 to 0.7 g/cm^
The method according to any one of claims 1 to 5, wherein the cellulose fiber paper is a cellulose fiber paper as in claim 2. 7. The method according to any one of claims 1 to 6, wherein the unsaturated polyester resin liquid has a viscosity of 0.5 to 15 poise at 25°C. 8. Claims 1 to 7, in which the unsaturated polyester resin liquid is mainly composed of an unsaturated polyester chain made of an unsaturated dibasic acid, a saturated dibasic acid, and a glycol, and a crosslinking vinyl monomer. Either way.