JPH0139908B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for continuously producing a laminate and a metal foil-clad laminate in which sheet-like substrates impregnated with a thermosetting resin are stacked one on top of the other. It is particularly aimed at metal foil clad laminates used in laminated insulating boards and printed circuit boards used in electrical applications. In the present invention, the term "laminate" refers to both a laminate, which is often used as an insulating plate without a metal foil laminated on the surface, and a metal foil-clad laminate. The laminate has excellent heat resistance against soldering temperatures up to 260℃, excellent electrical insulation properties, dielectric properties, punching processability, chemical resistance, peel strength of metal foil, and surface smoothness of the laminate. It is required that no harmful volatile substances with odor or toxicity are emitted during heating. Furthermore, it has many advantages, such as not causing troublesome large warps during printing or heating processes, not containing air bubbles that impair thermal conductivity and degrading quality, excellent dimensional stability under various environments, and low cost. characteristics are required. The shape of the laminate is, for example, about 0.5 mm to 5 mm thick.
mm, and the practical dimensions are usually approximately 1 meter square.
It is a plate-like object with a smooth surface. Conventionally, these laminates were made by impregnating the base material with a varnish made by dissolving resin components in a solvent, then drying the solvent to create a prepreg, which was then cut to a certain size, and then stacked in multiple layers and pressurized using a batch method. It was manufactured using methods such as heating. In this conventional method, the prepreg must be non-adhesive due to workability and process constraints, which limits the resin component and requires a solvent, resulting in a complicated manufacturing process. The reality is that there is a big problem with productivity. In addition, conventional metal foil clad laminates are made by impregnating the base material with a varnish in which a resin component is dissolved in a solvent.
Next, the solvent is dried to make a prepreg, which is cut to a certain size, which is stacked in multiple layers.On top of that, an adhesive-coated metal foil that has been previously coated with adhesive and baked to state B is added. It was manufactured using the batch method of stacking layers and then applying heat and pressure. These products are used, for example, as circuit boards for printed wiring, but the actual situation is that the process is complicated and that they are produced in batches, which requires manpower and poses a major problem in productivity. In recent years, from this point of view, several proposals have been made to continuously produce laminates or metal foil clad laminates (U.S. Pat. No. 3,236,714, U.S. Pat. No. 4,012,267, Japanese Patent Application Laid-Open No. 1988-88872). Publication No.). However, all of them have the following problems, and the advantages of continuous production methods cannot be fully utilized in terms of cost and characteristics, and the current situation is that they have not been fully put into practical use. That is, a. When using a solvent-based resin varnish that requires a drying step, the resin component that is attached to the substrate after drying usually becomes an extremely highly viscous semi-fluid or solid. Since the surface of the base material to which such a resin component is attached is not a mirror surface, when multiple layers of base materials are stacked, voids or air bubbles are created between the layers. Eliminating these voids and air bubbles requires extremely difficult equipment that requires heating and considerable pressure during lamination, and that such high pressure must be maintained during the curing process. Additionally, the drying process requires a drying oven and solvent recovery equipment, reducing its advantages over conventional methods. b. Furthermore, when using a thermosetting condensation resin that generates reaction by-products such as gas and liquid during the curing reaction process, even if it is a resin liquid that does not require the drying process as described above, the generation will occur. A similar difficulty exists in that pressurization must be maintained during the curing process in order to avoid adverse effects such as foaming due to by-products. c. To solve the difficult problem of maintaining pressure during the curing reaction process for continuously conveyed molded products, localized application methods such as installing many pairs of heated pressure rolls in series can be used. It is easy to come up with a compromise solution that involves a list of pressures. However, according to experiments conducted by the present inventors, in such a method, the pressure applied to any fixed point of the molded body fluctuates greatly periodically, causing internal air bubbles to swell, etc. No laminate is obtained.
Furthermore, applying pressure periodically when the resin component is uncured in a fluid or semi-fluid state due to heating causes unnecessary flow of the resin component.
For example, the surface becomes corrugated, making it almost impossible to obtain a desirable product. Therefore, a highly rigid plate-like material such as an iron plate was continuously supplied between the compact and the pressure roll to solve the problems of localized pressure and pressure fluctuations, but this had the disadvantage of requiring complicated equipment. The weight ratio of the thermosetting resin liquid impregnated and adhered to the base material to the base material is an important issue in quality design of the laminate. However, in the present invention, as described later, the curing or molding of the laminated base material is performed under no pressure conditions, so unlike the conventional pressure press method, excessive resin is It is not possible to remove the portion. However, at the time when sheet-like or film-like coatings are laminated on both sides of the resin liquid-impregnated base material laminate, the weight ratio of the resin liquid amount of the resin liquid-impregnated base material before curing is less than 10% of the base material. In this case, the plurality of sheet-like base materials do not bond well even during curing, and as a result, local peeling occurs after curing, or the base materials sometimes separate into pieces. Even in cases other than such extreme cases, many products were unsatisfactory in terms of heat resistance and mechanical strength due to insufficient effectiveness as a composite laminated material of resin and base material. Note that the weight ratio of the resin liquid amount of the resin liquid-impregnated base material is expressed by the ratio of the weight of the impregnated resin liquid to the weight of the resin liquid-impregnated base material. Weight ratio of thermosetting resin liquid to base material is 90%
In the case of an excess of more than This may cause a certain amount of resin liquid to flow out from both edges of the film-like or sheet-like coating, making it impossible to secure the necessary weight ratio of the resin liquid amount, and the flowing resin liquid may harden. This caused the inconvenience of contaminating the inside of the furnace. In addition, such a high resin liquid ratio causes uneven distribution of the base material in the resulting laminate, making it difficult to obtain a homogeneous product. If a highly porous base material is used to achieve a higher resin ratio, such a base material often has poor mechanical strength, and in a continuous manufacturing method such as the present invention, a long base material is continuously conveyed. The inconvenience of frequent breakage during the process occurred, and even if a temporary product was obtained, the reinforcing effect of the base material inside the laminate was insufficient, and in many cases, the mechanical strength was particularly insufficient. The method of the present invention essentially involves impregnating a sheet-like base material with a thermosetting resin liquid that does not require drying and generates almost no reaction by-products such as gas or liquid during the curing reaction process. A laminate is continuously produced by continuously conveying a plurality of sheets of material, then continuously laminating (overlapping) them, and curing them continuously and under no pressure. Furthermore, in the method of the present invention, the weight of the resin liquid relative to the impregnated base material (i.e., the base material impregnated with the resin liquid) at the time when the film-like or sheet-like covering is laminated on the resin liquid-impregnated base material laminated pair. It is characterized by carrying out a step of adjusting the ratio to a range of 10 to 90%, preferably a range of 20 to 80%, particularly preferably a range of 30 to 70%. As a means of adjusting the weight ratio of the thermosetting resin liquid,
There are the following methods. a When impregnating a film-like or sheet-like substrate with a thermosetting resin liquid, an excessive amount of liquid is supplied in advance in the impregnating device, and the excessive amount of resin is applied to the surface of the substrate to form multiple substrates. In the process of continuously conveying materials, slits 33 corresponding to the thickness of each base material are formed.
(Fig. 1) By adjusting the slit interval, the excess resin is scraped off and the amount of adhering resin is adjusted appropriately, and then sent to the laminating device 3 to laminate the base material. Do this. b A squeezing roller 34 (Fig. 4) is provided between the impregnating device 2 and the laminating device 3, and the squeezing roller 34 squeezes out the excess resin liquid from the base material that has been impregnated with the resin liquid in excess. After adjusting the amount appropriately, it is sent to a laminating device 3 to laminate the base materials. c When multiple resin liquid impregnated base materials are laminated using a laminating device composed of a pair of rollers or a combination of a roller and a blade (see Figures 1, 4 to 6).
(Figure), the roller interval or the interval between the roller and the blade can be adjusted, and by adjusting the lamination interval, excess resin liquid in the resin liquid impregnated base material is removed, and the resin liquid is laminated while maintaining an appropriate amount of resin liquid. d A laminating device 23 (Fig. 4) consisting of a pair of rollers is provided on the exit side of the laminating device 3, so that the interval between the rollers of the laminating device 23 can be adjusted when laminating the coating on both sides of the laminated base material. , the coating is laminated while removing excess resin liquid from the laminated substrate by adjusting the spacing. e By combining methods a to d above, excess resin liquid is removed in several stages, and a laminate with an appropriate amount of resin liquid is finally obtained. f Continuously transporting the resin liquid impregnated base material, continuously laminating the base material, continuously transporting the laminated base material to a laminating device, and laminating the coating onto the laminated base material. In one or more of the steps, a thermosetting resin liquid is applied to the surface of the film-like or sheet-like base material or the surface on which the laminated base material and the coating are to be laminated by a supply device 35 (FIG. 4). The weight ratio of the resin liquid to the base material is adjusted appropriately. By combining one or more of the methods g a to e with the method f, the amount of resin liquid impregnated into the laminate is finally adjusted to the optimum amount. The above-mentioned thermosetting resin liquid does not contain a solvent component that is essentially unnecessary for curing, and is mainly composed of a type of thermosetting resin in which the entire resin liquid component becomes a component of the thermoset product. , and refers to a resin liquid that does not substantially generate reaction by-products such as condensed water or carbon dioxide gas during curing. For example, they are radical polymerization type or addition reaction type resins such as unsaturated polyester resins, vinyl ester resins, epoxy acrylate resins, diallylphthalate resins, and epoxy resin liquids. Therefore, condensation type resin liquids containing, for example, phenolic resins, melamine resins, etc. as main components are excluded in the present invention. Note that thermosetting resins contain materials for curing, as is usually done. For example, if the resin liquid is an unsaturated polyester resin liquid,
It contains polymerizable monomers and curing catalysts for crosslinking, and in the case of epoxy resins and other resin liquids, it contains a curing agent. The method of the present invention is used to obtain a good finish on the surface layer of the laminate, especially when the thermosetting resin is of a radical polymerization type and contains a curing catalyst, in order to block oxygen in the atmosphere and perform good curing. At the same time as the lamination or after the lamination, film-like or sheet-like coverings are laminated on both sides of the resin liquid-impregnated laminated base material. The coating laminated onto the surface of the laminate is peeled off by winding or the like after the resin liquid has hardened, if necessary.
It is preferable to collect and reuse the peeled coating because it can reduce the manufacturing cost of the laminate. When producing a single-sided or double-sided metal foil-covered laminate, by laminating a metal foil that is not intended to be peeled off as a coating on one or both sides of the laminate, the coating accelerates curing by coating the surface of the laminate. Not only does it work, but it is also very rational as a component of a product. In the continuous production of laminates, the present invention allows the sheet-like base material to be modified according to the characteristics, intended use, and manufacturing conditions of the product before impregnating the sheet-like base material to be used with a thermosetting resin liquid. This is a method in which the material is subjected to an appropriate press impregnation process and, if necessary, a drying process is added after the pre-impregnation process. In particular, when impregnating a cellulose base material with an unsaturated polyester resin liquid in the impregnation process, the base material is simply pre-impregnated with a solution of an N-methylol compound and dried to remove the solvent. However, it is possible to create an electrical laminate with excellent properties. In the method of the present invention, when impregnating a sheet-like substrate with a thermosetting resin liquid, the resin liquid is exposed to an environment below atmospheric pressure and subjected to a reduced pressure treatment, and then the resin liquid is applied to the sheet-like substrate under reduced pressure. This method shortens the impregnation time with the resin liquid and almost completely eliminates the incorporation of air bubbles into the product. The present invention further makes it possible to cut the laminate with a cutter when heating the sheet-like substrate impregnated with the thermosetting synthetic resin liquid and proceeding with the curing process continuously and under virtually no pressure. In addition, the laminate can be cured as it hardens by cutting it into practical dimensions in the initial cured state in which the coating laminated on the surface of the laminate is cured to the extent that it can be peeled off without any problem, and further curing after cutting. This is a method that can reduce warpage and residual strain to a level that is practically acceptable. The present invention uses a thermosetting resin liquid that essentially does not require drying and generates almost no reaction by-products such as gas or liquid during the curing reaction process. Compared to the method that uses resin varnish, drying equipment and solvent recovery equipment for resin varnish are not required, and the properties of the resin liquid remain virtually unchanged from the impregnation process to the lamination process (the process of stacking multiple sheets of impregnated base material). It is. Therefore, for example, when sheet-like substrates sufficiently impregnated with a resin liquid are stacked together and the resin liquids come into contact with each other, since the resin liquid has a low viscosity, the incorporation of air bubbles during stacking can be minimized. In addition, there is no need to apply special heating or pressure in the stacking process. Furthermore, since there are virtually no trapped air bubbles or gases generated during curing, there is no need for difficult and unrealistic equipment to apply and maintain high pressure as described above. It has the advantage that it can be cured by heating and that products with excellent properties can be manufactured at low cost. The present invention is groundbreaking in that it has made it possible to continuously manufacture products with excellent properties by impregnating a sheet-like base material with a thermosetting resin liquid and curing it under no-pressure conditions. Therefore, unnecessary distortion of the product due to molding pressure during curing can be eliminated, and a product with excellent dimensional stability during heating, especially in the thickness direction, can be manufactured. If pressure is applied during curing, the resin impregnated into the base material will flow out, disrupting the uniform distribution of the base material and resin layer in the laminate, resulting in a decrease in electrical insulation performance. Since the process is carried out under pressure-free conditions, there is no need for special equipment to apply pressure, and the above-mentioned local pressure peeling method is unnecessary, making it possible to produce products with excellent surface smoothness. There are advantages. The term "no pressure" as used in the present invention means that the process is carried out under normal atmospheric pressure without any artificial pressurization operation. Strictly speaking, when laminating a film-like or sheet-like covering, the pressure of the weight of the covering is applied. However, in reality, such weight pressure does not exceed 0.01Kg/ ^cm2 , and is usually 0.01Kg/cm2.
Kg/cm ² to 0.001 Kg/cm ² , and such a slight pressure can be ignored in the present invention without impairing molding conditions such as flow and outflow of the resin. Furthermore, since the present invention does not require a complicated device that continuously performs heating and pressurization, the heating method and continuous transport method during curing can be selected quite freely. For example, a. Hot air is blown onto one or both sides of rolls arranged at 1 m intervals as supports for the object to be heated. b. A method well known as a floating dryer, in which a jet stream of heated air is sprayed from the upper and lower surfaces of the object to be heated, and the object is conveyed while floating in the air. c Transported on a heating plate using a heating medium or electric heat, and heated by heat transfer. d) Heating using a heating medium, electric heating plate, or radiant heat from a heated object. All of these are preferred methods that eliminate unnecessary pressure, heat cure, and allow continuous conveyance. The laminate produced by the method of the present invention has superior product thickness accuracy compared to products produced by the conventional batch method. For example, in the case of a laminate with a thickness of 0.5 mm, the range of thickness variation reaches 70 to 160 μ using the conventional method, but generally, the range of thickness variation of the laminate according to the present invention is at most 20 μ to 160 μ.
Within 30μ. Moreover, the coefficient of thermal expansion in the thickness direction is 40 to 60% of the coefficient of thermal expansion of the laminate manufactured by the conventional method. Furthermore, it is significantly superior in terms of lower manufacturing costs, higher manufacturing speeds, and simpler equipment. As shown in FIG. 1, the present invention applies a continuous drying device 12, an impregnating device 2, a laminating device 3, a continuous thermosetting furnace 4, and a drawing device to a sheet-like substrate 6 that is continuously fed from a substrate supply section 1. 13. The cutting devices 5 are arranged in sequence, and the continuous thermosetting furnace 4 is not provided with any pressurizing means,
The laminate 7 is manufactured continuously. The sheet-like base material 6 referred to in the present invention can be the same as the base materials used in conventional laminates, such as glass fiber cloth, glass fiber-based materials such as glass nonwoven fabric, kraft paper, linter paper, etc. Refers to sheets or strips of inorganic fibers such as paper and asbestos cloth, which are mainly made of cellulose fibers. When using paper as a sheet-like base material, from the viewpoint of impregnability and quality, the density (bulk specific gravity) when air-dried is 0.3 to 0.7 g/cm ³
Paper mainly composed of cellulose fibers, such as kraft paper, is preferred. Before impregnating the sheet-like base material with the thermosetting resin liquid, an appropriate pre-impregnation process and, if necessary, a drying process are performed depending on the characteristics, intended use, manufacturing conditions, etc. required for the product. Alternatively, a sheet-like base material that has undergone pre-impregnation treatment may be stored in the base material supply section 1. Alternatively, the pre-impregnation device 14 and, if necessary, the continuous drying device 12 are directly connected to the front stage of the thermosetting resin liquid impregnation device 2, and pre-impregnation is continuously performed on the sheet-like substrate 6 sent from the substrate supply section 1. I can do it. The continuous drying device 12 is installed to remove the solvent when the pre-impregnation device 14 performs pre-impregnation with a solution using a solvent. If the pre-impregnation is carried out by impregnation of liquid compounds without solvent or adsorption of gaseous compounds, the drying device 12 may be omitted if not required. The pre-impregnation process includes the following treatments, but is not limited to these, and of course may be changed depending on the characteristics required of the base material and the intended use. (1) If the base material is a glass cloth base material, pretreatment of the base material with various coupling agents and surfactants, such as treatment with a silane coupling agent (2) Various polymerizable monomers and thermosetting resin liquid (3) Impregnation of various thermoplastic resins into the substrate for the purpose of modifying the physical properties of the resulting laminate (4) Pre-impregnation with various thermosetting resin solutions (5) Pre-impregnation with various unsaturated fatty acids (6) Impregnation and reaction of reactive compounds with the substrate surface, such as acetylation of cellulose (7) One solution when using a resin liquid with a short pot life in the impregnation process Catalysts, reaction aids,
Pre-impregnation with hardening agent only (8) Impregnation with inorganic filler slurry liquid Among the various pre-impregnations mentioned above, in (1), the glass cloth substrate is pretreated with vinyl alkoxysilane, and then the impregnation step is performed. By impregnating the laminate with an unsaturated polyester resin liquid, it is possible to continuously produce a laminate with a bending strength 1.5 times that of one without pre-impregnation. In (3), kraft paper is coated with 10% polyethylene glycol in advance, and then impregnated with unsaturated polyester resin liquid in the impregnation process, making it resistant to impact against untreated materials. The performance will be doubled. In (7), a commercially available polyamide resin for curing epoxy resin is pre-impregnated onto a glass cloth base material so that the adhesion amount is 30% of the epoxy resin, dried, and then commercially available in the impregnation process. By impregnating with the epoxy resin liquid, the problem of pot life of the resin liquid in the storage tank or impregnation bath can be solved. It is desirable that the amount of impregnation deposited on the sheet-like base material in these pre-impregnation processes should be 50% or less of the base material. may be damaged. The pre-impregnation step is important for the following reasons. When paper mainly composed of cellulose fibers is impregnated with an unsaturated polyester resin liquid, the resulting paper-based unsaturated polyester resin laminate has various properties under normal conditions, such as electrical insulation, soldering heat resistance,
Although the copper foil peeling strength, punching workability, mechanical strength, etc. are extremely good, it has the drawback that the properties as a laminate may deteriorate due to moisture absorption. Although the unsaturated polyester resin itself has excellent electrical insulation, heat resistance, moisture resistance, and water resistance, it has poor adhesion to cellulose, which is the main component of the paper base material, and the resin and cellulose fibers do not adhere well due to moisture absorption. This is thought to be because the interface peels off, resulting in an increase in the amount of moisture absorbed, which in turn leads to a decline in various performances. Attempts to improve these drawbacks include a method of treating paper base materials with methylolmelamine or methylolguanamine (Japanese Patent Publication No. 38-13781), a method of formalizing paper base materials with formaldehyde (Japanese Patent Publication No. 40-29189), An example is known in which a base material is converted into acrylamide methyl ether with N-methylol acrylamide, washed with water, and then applied to a diallyl phthalate resin (Japanese Patent Publication No. 39-24121). However, methods of treating paper substrates with methylolmelamine or methylolguanamine and formalizing paper substrates with formaldehyde require the use of large amounts of these treating agents in order to obtain a sufficient effect, resulting in hard boards. It has the disadvantage of reducing punching workability. In addition, the method of converting cellulose into acrylamide methyl ether, as disclosed in Japanese Patent Publication No. 39-24121, requires a long time for the methyl etherification reaction, and also requires complex post-processing steps such as washing with water to synthesize acrylamide methyl etherified cellulose. , which is used as a base material to produce a laminate, and has the disadvantage that the punching properties of the resulting laminate are not good. As a result of repeated research, the inventors of the present application have invented a method that can prevent the deterioration of properties due to moisture absorption. The method involves using a polymerizable monomer used together with an unsaturated polyester resin, such as a vinyl monomer, to obtain N-N, which has a copolymerizable unsaturated bond as a functional group.
- An unsaturated polyester resin laminate is produced using cellulose as a base material, which is simply impregnated with a solution of a methylol compound and dried. As a result, an electrical laminate with excellent properties not only under normal conditions but also when absorbing moisture was completed. Moreover, this laminate can eliminate the various drawbacks of the conventional unsaturated polyester resin laminate described above. The drying process is characterized in that it is only necessary to remove water, alcohol, etc., which are the solvents of the N-methylol compound, and there is no need for any reaction between the cellulose and the N-methylol compound. The unsaturated polyester resin used in the present invention may be either liquid or solid at room temperature, but one that is liquid at room temperature is particularly preferred. The molecular structure of unsaturated polyester resin liquid is, for example, Generally well-known materials such as ethylene glycol, propylene glycol, diethylene glycol, etc. can be used.
1,4-butanediol and 1,5pentanediol, saturated polybasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, azelaic acid, unsaturated polybasic acids such as maleic anhydride, fumaric acid, etc. It is a mixture of glycols and a crosslinking monomer with these glycols. The polymerizable monomer used as a crosslinking monomer is generally styrene, but other examples include α-methylstyrene, vinyltoluene, chlorostyrene,
Monomers such as divinylbenzene, alkyl acrylates having 1 to 10 carbon atoms, alkyl methacrylates having 1 to 10 carbon atoms, diallyl phthalate, and triallyl cyanurate can also be used. The amount of these polymerizable monomers used is 20 to 50% by weight of the unsaturated polyester resin. In particular, a mixture of styrene and divinylbenzene gives good results when copolymerizability is good or for the purpose of reinforcing the mechanical strength of the resulting product. Furthermore, a general-purpose organic peroxide is added as a curing catalyst, and a curing accelerator is added as necessary during curing.
When curing an unsaturated polyester resin liquid, a curing catalyst (polymerization initiator) is usually added. In the case of thermosetting unsaturated polyester resins, organic peroxides are generally used, and the following are preferred. However, the following are not limited to:
Of course, known curing catalysts such as light-sensitive curing catalysts or radiation-sensitive curing catalysts can be used together with peroxide or alone. Although many organic peroxides for curing unsaturated polyester resins are known, the selection of the polymerization initiator is important since the invention relates to the production of new electrical laminates by pressureless molding. Decomposition products of organic peroxides remain in the product, albeit in small amounts. Electrical laminates and copper-clad laminates are usually heated at various temperatures between 100°C and 260°C during the processing process, and the above-mentioned decomposition products volatilize during the processing process, and in some cases, It emits an odor, and this odor is undesirable as it spoils the working environment. According to the research of the present inventor, when organic peroxides selected from aliphatic peroxides, particularly preferably aliphatic peroxyesters, are used alone or in combination, It was possible to produce an electrical laminate with significantly reduced odor. Aliphatic peroxides have the following general formula: ROOH, RmM(OOH)n, ROOR′, RmM
(OOR′)n, RnMOOMR′n, R(CO ₂ H)n,
RSO ₂ OOH, (However, R, R′, R″, R are aliphatic hydrocarbons, M
is a metal or metalloid. ) Specifically, for example, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, acetyl peroxide, isobutyryl peroxide, t-butylperoxy- 2-ethylhexanoate and the like. Odor is something that people sense and there are some individual differences, so it is necessary to give due consideration to the evaluation method. The present inventor conducted a detailed analysis by employing odor tests conducted by a large number of people, analysis of odor components using gas chromatography, and the like. Aliphatic peroxyesters have the following general formula: (However, R and R are aliphatic hydrocarbons, and n is an integer from 1 to 4 determined by the structure of R.) For example, t-butyl peroxyacetate, t
-Butylperoxyisobutyrate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaureut, etc. It is considered that the reason why aliphatic peroxides or peroxy esters are preferable is that aromatic catalytic decomposition products are not present among the volatile components generated during heating. If aromatic organic peroxides are used, aromatic decomposition products will volatilize, causing odor. The temperature and time conditions for curing the resin liquid vary depending on the organic peroxide used, but in the present invention, since molding is carried out under pressureless conditions,
In order to eliminate foaming due to vaporization of the liquid copolymerizable monomer at an early stage, curing is preferably started at a temperature of 100°C or lower, and thereafter at a temperature of 50 to 150°C.
A temperature range of . In electrical laminates and copper-clad laminates,
Heat resistance, dimensional stability under heating or moisture absorption conditions,
Advanced properties are required, such as punching properties, adhesive strength between the laminate and copper foil, and electrical insulation properties. Therefore,
For the purpose of these improvements, various additives, mixtures, fillers, etc. may be added to the unsaturated polyester resin liquid, and this does not limit the present invention in any way. The epoxy resin liquid to be impregnated into the sheet-like base material is a bisphenol A type epoxy resin, a novolak type epoxy resin, or a mixture thereof, and a mixture of these with a reactive diluent added as necessary, in combination with a curing agent. Can be used.
It is preferable to use a liquid type epoxy resin. As the curing agent, any well-known acid curing type or amine curing type can be used. In particular, in the present invention, when an epoxy resin liquid consisting of an epoxy resin and an acid anhydride curing agent is used,
Adjust the viscosity of the resin liquid to the appropriate viscosity for impregnating the base material, i.e. 25
The viscosity at °C is 0.5 to 30 poise, preferably 1
~15 poise is suitable. Hardeners commonly used as hardeners for epoxy are:
There are various amine-based, amido-amine-based curing agents, dicyandiamide curing agents, imidazole-based curing agents, etc., but when using bisphenol A type epoxy resin, which has good physical properties, it seems that the physical properties will be significantly deteriorated. It is difficult to adjust the viscosity to an appropriate range unless a large amount of diluent is used, and amine and amidoamine curing agents have short pot lives. On the other hand, dicyandiamide curing agents and imidazole curing agents have long pot lives;
It has the disadvantage of requiring a long period of time at high temperatures for curing. When using an acid anhydride curing agent, such a drawback does not exist, and the curing agent is suitable for the present invention. More specifically, regarding the epoxy resin liquid of the present invention, as the epoxy resin, bisphenol A type liquid epoxy resin is suitable, but other epoxies such as bisphenol F type and novolak type can also be used. If necessary, a solid epoxy resin or diluent may be mixed. As the acid anhydride curing agent, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylenditic anhydride, etc. can be used, as well as mixtures of these. Of course you can use it. Among them, methyl tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylendicic anhydride, which are liquid at room temperature, are suitable for the method of the present invention. As the curing aid, commercially available curing aids such as 2-
Ethyl-4-methylimidazole, boron trifluoride complex compounds, tertiary amines, benzylmethylamine, benzylmethylammonium chloride, tertiary amine salts, etc. can be used. Further, the sheet-like base material is preferably a long glass cloth. In particular, it is preferable to perform silane coupling treatment by pre-impregnation as described above. The N-methylol compound having an unsaturated bond as a functional group copolymerizable with the vinyl monomer used in the pre-impregnation of the present invention includes the following. Modified aminotriazine methylol compound. In other words, methylol compounds of aminotriazines such as guanamines or melamine (or compounds in which part or all of their methylol groups are etherified with lower alcohols such as methanol) have functional groups that can be copolymerized with vinyl monomers. This is a modified aminotriazine methylol compound with an unsaturated bond introduced. For example, a partial ester compound of an unsaturated carboxylic acid such as acrylic acid or itaconic acid and a methylol compound of aminotriazine; or a partial ether compound of an unsaturated alcohol such as allyl alcohol and a methylol compound of aminotriazine; or acrylamide, methacrylamide, etc. A condensation product of an unsaturated carbonamide and a methylol compound of aminotriazine; or a condensation product of an epoxy compound having an unsaturated group such as glycidyl methacrylate and a methylol compound of aminotriazine. general formula (However, R ₁ = H or CH ₃ R ₂ = H or a C _1-3 alkyl group) is an amidomethylol compound represented by
Among them, N-methylolated acrylamide, N-methoxymethylol acrylamide,
N-butoxymethylol acrylamide, N-
Methylol methacrylamide, N-methoxymethylol methacrylamide, N-butoxymethylol methacrylamide and the like are preferred for use.
One or a mixture of two or more of these or a co-condensate of two or more of these may be used. Furthermore, in addition to the above () and (), the above ()
In place of the modified aminotriazine methylol compound described in 1., mixtures of the following a and b are also included. a N-methylol compounds such as aminotriazine methylol compounds that do not have unsaturated bonds copolymerizable with vinyl monomers as a functional group b Modifiers for N-methylol compounds, i.e. condensation or addition with the N-methylol compounds in item a Compounds that have as a functional group an unsaturated bond copolymerizable with a vinyl monomer and a vinyl monomer, such as unsaturated carboxylic acids such as acrylic acid and itaconic acid, unsaturated alcohols such as allyl alcohol, or acrylamide and methacrylic acid. It is also an embodiment of the present invention to impregnate and dry a paper base material with an unsaturated carbon amide such as amide, or an epoxy compound having an unsaturated group such as glycidyl methacrylate.
(). Almost the same effect as when impregnated with the type of treatment agent () can be achieved. This is because a reaction occurs between the methylol compound of aminotriazine described in item a above and the modifier described in item b above during drying of the treated paper or during subsequent impregnation and curing of the unsaturated polyester resin. it is conceivable that. The main purpose of the present invention is to improve the adhesion between the unsaturated polyester resin and the paper base material and to prevent the deterioration of various properties when moisture is absorbed.In order to fully demonstrate the effect, it is necessary to The above () is used as a treatment agent for paper base materials. As shown in (), a compound having as a functional group an N-methylol group that can bond with cellulose and an unsaturated bond that can copolymerize with a polymerizable vinyl monomer that is a crosslinking agent for unsaturated polyester resin is used. Or, as shown in (),
It is necessary to use a mixture of an N-methylol compound that does not have as a functional group an unsaturated bond copolymerizable with the vinyl monomer a and a modifier for the N-methylol compound that has an unsaturated bond b. On the other hand, when the treatment is performed with a compound having only one functional group, either an N-methylol group or an unsaturated bond copolymerizable with a vinyl monomer, the effect is not sufficient. For example, if the treatment is performed only with methylolmelamine, which has only N-methylol groups, or if it is treated with acrylamide, which has only unsaturated bonds, the resulting laminate will not have sufficient performance when absorbing moisture. Nakatsuta. The concentration of the treated solution shown in () to () above used in the present invention is such that the amount of adhesion to the paper base (i.e., paper base only) after drying is 3 to 30 parts by weight, preferably 6 to 20 parts by weight. It is desirable to adjust the amount so that the adhesion amount is less than 3 parts by weight, and the effect is not sufficient, and if it exceeds 30 parts by weight, the plate becomes brittle when made into a laminate and the punching workability deteriorates. Solvents such as water, alcohols, ketones, and esters can be used as solvents for making these processing agents into solutions. Furthermore, in order to efficiently advance the etherification reaction between cellulose and the treated N-methylol groups, it is effective to add an acidic condensation catalyst or to increase the curing temperature of the paper after impregnation treatment. By such a method, it is possible to partially induce the etherification reaction of the cellulose prior to the subsequent impregnation and curing reaction of the unsaturated polyester resin, but no special effect of this reaction prior to curing is observed. . In the present invention, it is not necessarily necessary to proceed with the above-mentioned etherification reaction during the paper processing process.
Simply attaching a treatment agent to paper without adding a catalyst can sufficiently improve various performances during moisture absorption. On the other hand, depending on the type of catalyst added, the electrical insulation properties of the resulting laminate may be reduced, or the plate may become hard and its punching workability may be reduced. Note that, if desired, additives such as a polymerization inhibitor, a polymerization catalyst, a surfactant, and a plasticizer can be appropriately combined and added to the processing agent solution. The solvent is removed by impregnating paper base materials normally used for laminates such as kraft paper and linter paper, or in some cases cloth base materials, with these solutions using a dipping bath, roll coater, spray, etc., and then drying them. is removed to obtain a treated substrate. The drying mentioned here only needs to be carried out with the purpose of removing the used solvent, and there is no need to react the base cellulose with the processing agent. In addition, the paper base material was pre-impregnated with methylolmelamine, methylolguanamine, etc. (i.e., only methylol compounds that do not have as a functional group an unsaturated bond that can be copolymerized with a vinyl monomer) disclosed in the above-mentioned literature. A laminate was created using unsaturated polyester resin using the method of the present invention using a paper base material, and its performance was investigated. It was found that the electrical insulation due to moisture absorption and the soldering heat resistance were improved compared to the case without pretreatment. Although there was little deterioration and a considerable improvement was seen in terms of moisture resistance and water resistance, on the other hand, it was easy to crack due to impact, and therefore the punching workability of this material was not suitable for practical use. . It is believed that the punching processability is greatly influenced by the physical properties of the unsaturated polyester resin used, and the present inventor used paper that had undergone the above-mentioned pretreatment and examined a large number of unsaturated polyester resins on the market. However, there were none that had good punching workability and were of practical use. In view of the current situation, the present inventors conducted intensive research and found that known methylol does not have as a functional group an unsaturated bond that can be copolymerized with the vinyl monomer used for pretreatment of cellulose base materials. Even if the compounds methylolmelamine and methylolguanamine are used, in addition to the methylol compound, groups such as hydroxyl groups, carboxyl groups, amino groups, and amide groups that can be condensed with methylol groups are added to the molecule for the purpose of imparting flexibility. By mixing or condensing higher aliphatic derivatives having at least one of I found it. This will be explained in detail below. In the present invention, methylolmelamine and methylolguanamine (that is, methylol compounds that do not have as a functional group an unsaturated bond copolymerizable with a vinyl monomer) include melamine, formoguanamine, acetoguanamine, probioguanamine, and benzoguanamine. , initial condensation products of guanamines such as adipodiguanamine and formaldehyde, or those obtained by etherifying some or all of their methylol groups with lower alcohols such as methanol or butanol. Examples of higher aliphatic derivatives that are mixed or condensed with the above-mentioned methylolmelamine and methylolguanamine for the purpose of improving punching processability include the following. Namely, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid,
Saturated fatty acids such as stearic acid; oleic acid,
Unsaturated fatty acids such as erucic acid, linoleic acid, eleostearic acid, and linolenic acid; and esters of the above fatty acids and polyhydric alcohols such as ethylene glycol, polyethylene glycol, propylene glycol, glycerin, pentaerythritol, and sorbitol; aliphatic amides which are derivatives from fatty acids such as those mentioned above; and caprylic alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol,
Examples include saturated or unsaturated higher alcohols such as oleyl alcohol and linoleyl alcohol, ethers of higher alcohols and polyhydric alcohols; and aliphatic amines that are derivatives of higher alcohols. Also, oxyfatty acids and derivatives thereof such as ricinoleic acid can be used for the same purpose. In short, a group that can be condensed with the methylol group of methylolmelamine or methylolguanamine, such as a hydroxyl group, carboxyl group, amino group, or amide group, and a long-chain alkyl group that functions to weaken the cohesive force of methylolmelamine or methylolguanamine. It is a necessary condition for a punching processability modifier to have the following.
The number of higher aliphatic derivatives that meet these conditions is extremely large, but according to the results of studies conducted by the present inventors, when the number of carbon atoms is 8 or more, they are effective as punching processability modifiers. When using oleic acid, oleyl alcohol, and their derivatives, such as oleic acid monoglyceride, oleic acid diglyceride, oleic acid amide, and oleylamine, which have 18 carbon atoms and one unsaturated group, the performance of the resulting laminate becomes more balanced. It was also clear that the film could be removed easily and was a preferred embodiment of the present invention. By the way, the optimum amount of such a modifier to be used varies depending on the glass transition temperature of the unsaturated polyester resin used in the laminate, but it is usually 3 to 40 parts per 100 parts of methylolmelamine or methylolguanamine. within the scope of the department. The method for using it may be either by mixing the modifier and methylolmelamine or methylolguanamine in the form of a solution or suspension, or by condensing the two in advance. In this case, water, alcohols, ketones, esters, etc. are used as the solvent. In addition, the concentration of these processing agent systems is the same as the above-mentioned N-
As in the case of methylol acrylamide, the total adhesion amount on the cellulose fiber substrate after drying is 3.
It is desirable to adjust the amount to ~30 parts by weight, preferably 6 to 20 parts by weight. If the amount is less than 3 parts by weight, the effect will not be sufficient, and if it exceeds 30 parts by weight, the board will be brittle when made into a laminate. This results in poor punching workability. A solution or suspension of the treatment agent prepared under the above conditions is coated with a cellulose paper base such as kraft paper or linter paper, or in some cases a cellulose cloth base such as cotton or rayon, using a dipping bath, roll coater or After impregnation using a spray or the like, a treated base material from which the solvent has been removed is obtained by drying. Desirable drying temperature is usually 70 to 150°C, and drying time is about 1 to 60 minutes. Note that the unsaturated polyester resin liquid used may be the one described above. The two types of paper pre-impregnation treatments (paper pre-treatment) related to the present invention have been described above. The punching workability of the laminate obtained by this method is excellent, but in order to provide excellent low-temperature punching workability, the glass transition temperature of the cured product of the unsaturated polyester resin must be 20 to 80°C. It is desirable to use a resin of However, this is not limited to the case of paper pretreatment mentioned above.
In the present invention, the glass transition temperature is generally 20~
The present inventors have discovered that it has excellent punching workability at 80°C. When electrical laminates and copper-clad laminates are put into practical use, they are often stamped and punched, and therefore, excellent punching characteristics are required. Particularly in recent years, with the miniaturization of electronic components and the increase in the density of circuits, the current situation is that more advanced processing characteristics are desired. Conventionally, base material laminates impregnated with unsaturated polyester are made by impregnating crystalline polyester or polyester that is solid at room temperature as a solution with a crosslinking agent using a solvent, drying it to form a prepreg, and then molding it under heat and pressure. Laminated bodies have been created. Although the laminate produced by this method has a high glass transition temperature and excellent heat resistance, it has problems with punching workability, particularly during low-temperature punching, which is usually performed at about 50 to 80°C. As a result of intensive research to solve this problem, the present inventors have determined the glass transition temperature of a cured product of an unsaturated polyester resin composition and the optimum punching method for a laminate made of such a resin composition. It was found that there is a close relationship between processing temperature. The punching temperature of the laminate is the glass transition temperature of the cured resin composition or 20°C above the glass transition temperature.
It has been found that a temperature range of up to 10°C, particularly preferably a temperature range of about 10°C from the glass transition temperature, is suitable. The glass transition temperature of the cured product of the unsaturated polyester resin composition is 20 to 80℃, preferably 30 to 70℃
When a laminate is formed using the unsaturated polyester resin composition, the processing temperature during punching is in the range from the glass transition temperature of the cured resin composition to 20°C, particularly preferably in the range of 10°C. At the time, they discovered that it has excellent low-temperature punching workability, and arrived at the present invention. The punching workability referred to in the present invention is based on ASTM D617
-44, and evaluated based on the scoring criteria. The punching workability was determined to be "good" when evaluations in the range of excellent to fair were obtained for all evaluation items of the end face, surface, and hole. When placing emphasis on low-temperature punching properties, the glass transition temperature of the cured unsaturated polyester resin composition should be
An unsaturated polyester resin composition having a temperature of 20 to 80°C, preferably 30 to 70°C is used. Glass transition temperature is 80
If a material with a temperature exceeding 100°F (°C) is used, low-temperature punching may result in undesirable chipping or worm-eaten edges, cracks or clear bulges on the edges or around the hole, severe chipping on the hole wall, significant bulges around the hole, or holes. Significant tapering occurs, and when punching is performed at temperatures below 20°C, bulges or tapering around the holes will occur. In the latter case, although it is possible to perform a good punching process by cooling the test piece as the case may be, it is not practical. glass transition temperature
When an unsaturated polyester resin composition having a temperature in the range of 30 to 70°C is used, a product with particularly excellent low-temperature punching processability can be obtained. The punching temperature for low-temperature punching type products is usually around 50 to 80 degrees Celsius in related industries, but the present invention can perform good punching in a wide processing temperature range of about 30 to 80 degrees Celsius. Enables us to offer a variety of products. For unsaturated polyester resins when low-temperature punching characteristics are important, the raw materials used, such as the type of glycols, the copolymerization ratio of these with saturated dibasic acids or unsaturated dibasic acids, and the type and blending ratio of crosslinking monomers Therefore, the properties of the cured resin change, and therefore the properties of the produced laminate also change. The unsaturated polyester resins used for this purpose may be those mentioned above, but the glass transition temperature of the one mixed with a crosslinking monomer and cured is preferably in the range of 20 to 80 degrees Celsius, preferably 30 to 70 degrees Celsius. All such combinations are applicable. For example, specifically, unsaturated polyester with the following composition (molar ratio)

[Table] Inic acid = 2:1:1
65% unsaturated polyester and 35% styrene as above
Examples include resin liquids made of Among the above resin liquids, propylene glycol:
The resin liquid using resin with isophthalic acid: maleic anhydride = 2:1:1 has a glass transition temperature of approximately 70.
℃, but as a result of low-temperature punching evaluation of this resin liquid at 75℃, it showed very excellent low-temperature punching processability. In addition, the polymerizable monomer as a crosslinking monomer is
Styrene is generally used, but substituted styrenes such as vinyltoluene, chlorostyrene, dichlorostyrene, and divinylbenzene, vinyl acetate,
Acrylic esters, methacrylic esters (e.g. butyl acrylate, etc.), diallyl phthalate,
Polymerizable esters such as triallyl cyanurate or mixtures of these and styrene may be used, and the glass transition temperature of the cured product of the unsaturated polyester resin composition containing these polymerizable monomers is 20 to 20.
What is necessary is just to mix|blend so that it may fall in the range of 80 degreeC, preferably 30-70 degreeC. For example, a resin liquid prepared by mixing an unsaturated polyester resin with a composition of diethylene glycol, isophthalic acid, and maleic anhydride (3:2:1), styrene, and butyl acrylate in a weight ratio shown in Table 1 below can be used.

[Table] It is also possible to blend rubber, plasticizers, fillers, and other additives, but the cured resin composition obtained by blending these and curing is adjusted so that it falls within the scope of the present invention. There is a need. Rubbers include polybutadiene and/or maleated copolymers thereof. Plasticizers include commercially available ester plasticizers made from adipic acid or phthalic acid and glycols, epoxidized soybean oil, and the like. Examples of inorganic substances include calcium carbonate, silicic anhydride, and titanium oxide, which are used as fillers for unsaturated polyester resins. As the base material, the above-mentioned well-known materials can be used, but particularly desirable products can be obtained when paper is used as the base material. The laminates and copper-clad laminates produced in this way exhibit favorable punching properties at processing temperatures of 30 to 80°C, and the present invention overcomes the drawbacks of conventional unsaturated polyester base laminates. In addition to solving this problem, we were also able to obtain a product with better punching workability than conventional phenol laminates. In the present invention, when impregnating a sheet-like base material with a resin liquid, sufficient consideration must be given to the fact that the viscosity of the resin liquid to be impregnated is higher than when impregnating with a so-called varnish, which is a mixture with a solvent, as in the conventional method. is necessary. The impregnating device 2 has two methods: as shown in FIGS. 4 to 6, the base material 6 is impregnated with the resin liquid while being passed through a bath containing the resin liquid, and as shown in FIG. There are curtain flow methods and others in which resin liquid is supplied from a nozzle to the upper surface of the shaped substrate 1. Care must be taken when using the dip type impregnation method as it tends to leave air bubbles inside the base material. A method of impregnating from one side, such as a curtain flow method, has the mechanical advantage of being able to impregnate a large number of sheet-like substrates at the same time, and is superior in that air bubbles can be easily removed. However, with this method, even at the stage where the resin liquid starts to wet the top surface of the base material and macroscopically impregnates the bottom surface, especially when the base material is paper, microscopically it contains many air bubbles. . However, the bubbles gradually disappear, and it usually takes 7 to 20 minutes until they are almost gone. Some of the air bubbles seem to disappear during the curing process, but if the layers are laminated and cured before the air bubbles disappear as mentioned above, the product will contain small air bubbles inside. This impairs the thermal conductivity of the laminate, thereby causing undesirable overheating of electronic components mounted on the product, and impairing the transparency and quality of the laminate. Of course, the impregnating properties vary depending on parameters such as pressure, viscosity, wettability (contact angle) between the base material and the resin liquid, time, etc., but generally exhibit the above-mentioned aspects. As mentioned above, the fact that the impregnation time usually takes about 7 to 20 minutes means that the distance that the impregnated substrates must be transported individually from the start of impregnation until the resin liquid-impregnated substrates are laminated (overlaid) is increased. The need for a longer line or the overall line speed (conveying speed) may be limited to a low speed. However, for practical use, it goes without saying that it is preferable to secure a faster impregnation rate. Air bubbles in products produced by conventional methods are largely correlated with impregnation conditions and heating and pressure conditions during curing; the longer the impregnation time, the fewer air bubbles inside the impregnated base material, and the higher the molding pressure. , is said to be advantageous because it dissolves residual air bubbles into the resin layer during curing. However, long impregnation times and high molding pressures are disadvantageous because they reduce productivity and increase the size of the equipment. In the present invention, by treating the resin liquid under reduced pressure,
It is characterized by the ability to almost completely eliminate air bubbles in the product even with a short impregnation time and virtually no molding pressure during curing. According to this method, the impregnation time could be shortened to 1/3 to 1/10 compared to other methods that use the same impregnation method and the same manufacturing method but do not apply reduced pressure treatment. The term "reduced pressure treatment" as used in the present invention means a treatment in which a resin liquid is exposed to an environment at atmospheric pressure or lower. Therefore, for example, a resin liquid containing a curing catalyst is placed in a pressure-resistant container, and the space inside the container is depressurized. Alternatively, the resin liquid is injected into a vacuum container at any time. Alternatively, the resin-impregnated base material may be once treated in a reduced pressure container, but the present invention is not limited thereto. In the case of the first two, there is no problem in contacting the atmosphere during impregnation. Once the liquid is depressurized, it is released into the atmosphere in the container.
Even if you leave it for 30 to 60 minutes, the effect will not be lost. The reduced pressure conditions are determined by the vapor pressure of the solvent and monomer in the resin liquid, and are preferably about 2 to 100 mmHg. Although the treatment time varies depending on the treatment method, a few minutes is sufficient for the method of dropping the resin liquid into a vacuum container. Decompression treatment is suitable for resin liquids that do not require large amounts of easily volatile solvents, can be impregnated, do not substantially generate reaction by-products such as gas or liquid during the curing reaction process, and can be molded without pressure. It is more effective. This is because it is not limited by the reduced pressure treatment conditions caused by solvents and can be virtually pressureless molded, but the risk of bubble generation under these molding conditions can be safely avoided, and pressurization is not required during curing. do not. In particular, an unsaturated polyester resin that is liquid at room temperature is one of the most preferred embodiments of the present invention, and any commercially available resin having a viscosity of about 0.1 to 15 poise can be used. Styrene is generally used as a crosslinking monomer for unsaturated polyester resins, but the vapor pressure of styrene at room temperature is about 6 mmHg, and it is preferable to use styrene in the present invention as well. The proportion of styrene in the resin liquid is 30~
The amount is generally about 50% by weight. In this case, a method of injecting into a container with a pressure of about 2 to 30 mmHg can sufficiently achieve the purpose. The apparatus shown in Fig. 1 continuously performs the above-mentioned vacuum treatment on the impregnating resin liquid, and further supplies the vacuum-treated resin liquid continuously to a large number of sheet-like substrates being transported. be. The resin liquid storage section 8 is connected through a pipe 15 to the upper part of a pressure reducing device 9 formed of a cylindrical closed container. The pipe 15 has one end opened at the bottom of the resin liquid storage section 8 and the other end connected to a nozzle provided at the top of the pressure reducing device 9.
The resin liquid is extracted from the reservoir 8 and is ejected through the pipe 15 into the pressure reducing device 9 . The amount of ejection may be controlled by providing a stop 16 in the nozzle of the pressure reducing device 9 or by using a liquid supply pump (not shown). The pressure reducing device 9 is provided with a degassing port on the side, and is connected to an oil rotary vacuum pump 19 via a leak valve 17 and a cold trap 18, so that the inside of the pressure reducing device 9 is reduced to negative pressure, preferably to 30 mmHg or less. The degree of vacuum is controlled by a manometer 20. The lower part of the pressure reducing device 9 is connected to the impregnating device 2 via a resin liquid supply pump 21. The resin liquid extracted from the resin liquid storage section 8 and spouted into the pressure reducing device 9 falls into the cylindrical closed container of the pressure reducing device. Reduce the falling distance in decompression device 9 to 50~
The decompression process usually ends when the distance is about 100 cm.
If a certain amount of the fallen resin liquid is always present at the bottom of the container, the reduced pressure treated resin liquid can be stably supplied. When it is necessary to adjust the back pressure according to the capacity of the resin liquid supply pump 21, place a cylindrical sealed container above the supply pump, or place the reduced pressure treated liquid in a storage tank (not shown). figure)
May be stored in Next, the resin liquid is supplied to the impregnation device 2 by the supply pump 21, but when an impregnation bath is used, an apparatus in which the resin liquid remains in the bath for a long time is not preferable. A method of supplying the resin liquid from a plane, such as a curtain flow method, in which the resin liquid can be directly supplied to the base material is suitable. The overflowing resin liquid is collected in the resin liquid storage section 8 and subjected to the depressurization treatment again. A large number of base materials impregnated with resin liquid are continuously conveyed, and then they are stacked on top of each other using a laminating device 3 composed of, for example, a pair of rolls, and at the same time, coating films or metal foils to be bonded are laminated on both sides. Then, it is transported into the thermosetting furnace 4 in a pressureless state. After curing, it is cut into a predetermined length to obtain a laminate 7 or a metal foil clad laminate. Decompression treatment can be applied to any material used in conventional methods, such as paper whose main component is cellulose fiber, glass cloth, glass fiber non-woven fabric, asbestos cloth or synthetic woven fabric, and synthetic fiber non-woven fabric. Cloth is especially effective. This method is surprising in that it can ensure excellent productivity, and although the inventor has not fully elucidated the reason for this fact, As a result of the reduction in the amount of dissolved air in the resin solution, the amount of air that can be dissolved in the resin solution increases after treatment, so that the air trapped in the substrate during impregnation can be dissolved into the impregnated resin solution at a sufficient rate to cure. It is assumed that the bubbles inside will disappear before the end of the process. Although the reduced pressure treatment is thought to have the effect of removing air bubbles that are trapped when a catalyst, modifier, etc. are mixed into the resin liquid, this is not the main focus of the present invention. It is well known that a resin liquid that can be allowed to stand still is treated under reduced pressure for the purpose of defoaming the viscous resin liquid. The conventional depressurization process for defoaming is
It is considered that this is not the same as the depressurization treatment carried out in the present invention. This is because even if paper is impregnated with a 4-poise unsaturated polyester resin liquid that has been left to stand still and sufficiently defoamed, the impregnation speed is the same as that before it was left to stand still. However, if the resin liquid is subjected to the reduced pressure treatment described in the present invention,
It is presumed that if the paper is then intentionally stirred to impregnate the paper containing air bubbles, the time for the air bubbles to disappear inside the impregnated paper will be significantly shortened. In any case, by carrying out the vacuum treatment according to the present invention, the time required for the bubbles in the impregnated paper to disappear is usually clearly 7 minutes or less, and 2 to 5 minutes. A similar effect can be obtained when a glass cloth base material is impregnated with an epoxy resin liquid. In the reduced pressure treatment method of the present invention, rather than exposing the resin liquid that can be allowed to stand under reduced pressure as described above, it is preferable to increase the surface area of the resin liquid to be treated, such as by ejecting it into a reduced pressure container. According to this method,
The effects of the present invention will not be lost even if the temporary treatment liquid contains air bubbles and the air bubbles are further drawn in during supply. The reduced pressure treatment according to the method of the present invention has the effect of reducing dissolved oxygen, thereby eliminating the influence of oxygen on the radical reaction during curing of the unsaturated polyester resin. In the case of unsaturated polyester resins that are liquid at room temperature, common commercially available products contain about 0.03 to 0.1% water. This can be achieved by the depressurization process of the present invention.
Setting the content to 0.04% or less, preferably 0.02% or less is preferable in terms of manufacturing and product performance since it eliminates bubbles caused by moisture and does not inhibit the curing reaction. In the lamination process, multiple sheets of resin liquid-impregnated base materials converge, forming rolls, blade-like objects,
Alternatively, it is laminated using two rolls. On this occasion,
The distance between the roll and the blade-like material or between the rolls is adjusted according to the desired product thickness so that excess resin impregnated or attached to each impregnated substrate can be removed. At the same time as the lamination or afterwards, a covering is laminated using a laminator installed separately, but the width of this covering is such that it protrudes from both ends of the laminated resin liquid-impregnated base material. Good. When such a coating is used, even if an excess resin liquid is squeezed out from the end of the resin liquid-impregnated substrate laminate during lamination, it is possible to retain the resin liquid, which is preferable. In the present invention, sheet-like base materials are laminated, and film-like or sheet-like coverings (hereinafter simply referred to as "coverings") are applied to the upper and lower surfaces.
After lamination (sometimes abbreviated as ), continuous pressure is essentially unnecessary during the curing process, so that a wide variety of coatings can be selected depending on the purpose. For example, if the resin to be impregnated is unsaturated polyester resin or epoxy resin, the thickness is 10~
Various release papers of about 200 μm, cellophane, various synthetic resin films such as Teflon and polyester, and various metal foils such as aluminum, copper, stainless steel, iron, and phosphor bronze can be used. As shown in the embodiment of FIG. 4, the coating 10 is peeled off from the laminate after the resin liquid has hardened, and
If it is rolled up, the coating can be reused, which is desirable from a cost standpoint. For this purpose, it is preferable that the coating is easily peeled off from the cured laminate, and the thermosetting resin and the coating are appropriately combined, and a release agent is used if necessary. In the present invention, it is preferable to use the coating in the form of an endless belt, as this allows the coating to be continuously peeled off and reused. In this case, a sheet material with a thickness of about 1 mm can be used, and the material is stainless steel,
Phosphor bronze and Teflon are preferred. The mold release agent is applied in advance to the entire surface or both edges of the surface of the coating that is in contact with the surface of the laminate before laminating the coating. If a mold release agent is applied to the entire surface of the coating, the mold release agent may migrate to the product laminate, which may impair the printing performance of various pastes or resists on the product, which may be undesirable. In such a case, it is preferable to apply the mold release agent to both edges of the laminate. This is because the laminate is in the thermosetting furnace 4.
By peeling off the coating and removing both edges of the product after passing through the mold release agent, the area to which the mold release agent has been applied will not become a product, so the unfavorable effects mentioned above can be eliminated. A suitable mold release agent is a silicone mold release agent, such as Daifree MS743.
(trade name, manufactured by Daikin Industries, Ltd.) gives good results. Among the product characteristics, smoothness is important for printing resistive pastes and resists on products, and transparency is important for the shape of these printed patterns and as described below.
This is significant because it makes it easier to see the circuit pattern on the printed circuit board from the back side. In the present invention, the required number of base materials impregnated with resin liquid are laminated, but at this time, a roll or blade-like object is used to remove excess resin liquid or air bubbles that are mixed in during lamination. However, it is desirable to control the amount of resin required. At the same time as the sheet-like base materials are laminated (Fig. 1), or laminated by a laminating device 23 (Fig. 4) comprising a pair of rolls installed downstream of the laminating device, at this time Compressive force acts on the laminate of resin liquid-impregnated base materials. Generally, the surface of the base material is not macroscopically or microscopically smooth at this point, so if a coating with low rigidity is used, the coating will follow these microscopic and macroscopic irregularities, and in the present invention, However, because the product is cured under no-pressure conditions, the surface properties of the product may not be sufficient. According to the research of the present inventor, the rigidity value of a film or sheet material defined by E・d ³ Kg・cm (where E is the modulus of elasticity Kg/cm ² and d is the thickness cm) is 3× 10 ^-3 Kg・
cm or more, a practically preferable surface smoothness was obtained. Furthermore, more desirable results are obtained when the stiffness value is 5×10 ⁻¹ Kg·cm or more. The present invention is achieved by covering both sides with such a coating and curing the resin liquid. In the present invention, as a base material, the thickness is 200~
Linter paper or kraft paper with a diameter of 300μ and a basis weight of around 150g/m ² is suitable. These papers usually have microscopic irregularities as shown in Figure 2, but they cannot be coated with a stiffness value of less than 3 × 10 ^-3 Kg cm, such as a thickness of 35 μm.
polyester film (flexural modulus is 28100)
Kg/cm ² and therefore the stiffness value is 1.54×10 ^-3 Kg・cm
As shown in FIG. 2, if a film is used, the film will follow the unevenness of the paper, resulting in a product with poor surface smoothness. The rigidity value of the coating is 3Kg×10 ^-3
If it exceeds Kg/cm, the ability to follow the irregularities of the base material will be reduced. For example, when a polyester film with a rigidity value of 2.81×10 ⁻² Kg·cm and a thickness of 100 μm is used, as shown in FIG. 3, the following of the unevenness of the base material is slight. More preferably, a coating with a stiffness value of 5×10 ⁻¹ Kg·cm or more, such as an aluminum foil with a thickness of 100 μm (flexural modulus of elasticity of 0.67×10 ⁶ Kg·cm ² and therefore a stiffness value of 6.7×10 ^-1 Kg·cm) or stainless steel foil with a thickness of 100 μm (flexural modulus is 18600 Kg/cm ² , therefore, rigidity value is 1.86 Kg·cm), etc. are suitable in the present invention. The coating may be a single film or sheet, or a composite film or sheet. In general, stiffness decreases with increasing temperature, but in the present invention the stiffness value at room temperature is applied, since covering the laminate with the coating is usually possible at room temperature, but especially at the curing temperature for plastic films. It is not preferable that the stiffness value decreases significantly. Also, those that have high adhesiveness to cured unsaturated polyester resins, epoxy resins, etc. are not preferred. From this point of view, cellophane, polyester, polypropylene, Teflon, polyamideimide film, etc. are suitable. Also, aluminum foil, rolled copper foil, and stainless steel foil are suitable. As described above, in the present invention, the coating can be easily peeled off without using a special release agent or release paper between the coating and the laminate, and there is no need to insert release paper. be. If a film-like material is inserted for the purpose of mold release, it is preferably a composite sheet-like material bonded to a coating. The coating is desirably long so that it can be continuously fed out from a roll and recovered while being rolled up after peeling. Furthermore, if the coating is formed into an endless belt, it can be used continuously and repeatedly. For such use, the stiffness value of the coating is 3
It is preferable to have a weight of ×10 ⁻³ Kg·cm or more and flexibility. If the rigidity is too high, the flexibility will be reduced, so a range of 3×10 ⁻³ Kg·cm to 3×10 ⁺¹ Kg·cm is suitable. As can be easily inferred from FIG. 3, the surface and geometric properties of the product are influenced by the surface roughness and geometric surface properties of the coating. The surface condition of a product is one of the extremely important characteristics, especially for laminates for electrical applications. For example, when manufacturing a film-type composite carbon resistor by applying resistance paste to an insulating substrate, if the surface roughness of the insulating plate is large, abnormal protrusions or pinholes may occur in the applied resistor. ,
The protrusions and pinholes cause noise during use and shorten the service life. The preferred surface smoothness is Rmax (maximum height of surface roughness) of approximately 5
It is less than a micron, more preferably less than about 4 microns. On the other hand, if Rmax becomes significantly small, the adhesive force between the resistor paste and the surface of the insulating substrate decreases, and the applied resistor may peel off. The adhesiveness between the resistance paste and the insulating substrate is determined by chemical factors, ie, the compatibility or polarity of the resistance paste and the insulating substrate, and physical factors, ie, the surface roughness of the insulating substrate. If it is approximately 0.4 microns or more, the adhesiveness between the coated resistor and the substrate and the transferability of the paste are good. Surface smoothness conformed to JIS-B0601. The measurement was carried out using a stylus type surface roughness measuring machine under the conditions of a stylus tip radius of 2.5 microns and a measuring force of 0.1 g. In the present invention, the above-mentioned laminate can be obtained by using a film or sheet-like coating having a surface roughness of 0.4 microns or more and about 5 microns or less. Although the case where the base material is paper has been described above, the same applies to the case where other base materials are used. For example, in the case of glass cloth, there are irregularities due to the texture, but this is not a problem.
It is obvious that the present invention is applicable. The above describes an electrical laminate in which both sides are covered with a coating.The coating described above is laminated on one side of the laminate of impregnated base materials and is peeled off after the resin liquid hardens, but the other side of the laminate is By laminating metal foil for lamination, which is a type of coating but not intended to be peeled off, or by laminating metal foil for lamination on both sides of the laminate for the purpose of bonding. Electrical laminates with excellent surface smoothness can be manufactured. Electrolytic copper foil for use in printed circuit boards is widely available on the market as metal foil for lamination.
It is preferable to use this from the viewpoints of corrosion resistance, etching properties, adhesion properties, etc. Next, electrolytic copper foil intended for printed circuit boards,
A single-sided metal foil-clad laminate and a double-sided metal foil-clad laminate in which electrolytic iron foil, aluminum foil, or the like is laminated on one or both sides will be described. When using a commercially available electrolytic copper foil of, for example, 1 oz/ft ² , the smoothness of the surface of the copper foil may be slightly lower than that of a conventional press-formed product, especially if the base material is paper, for the reasons mentioned above. Although it may be inferior in some cases, according to studies by the present inventors, this does not have any adverse effect on screen printability, etching, or other properties. For example, in the present invention, when an unsaturated polyester resin is used, even if electrolytic copper foil or the like is directly bonded by the method described above, a practical product can be manufactured if carefully carried out. In order to obtain a product with even higher performance, adhesive is continuously supplied between the metal foil and the laminate when laminating the resin-impregnated base material or when continuously laminating the metal foil to the laminate after lamination. By doing so, a more preferable metal foil clad laminate can be obtained. In the conventional batch production method that requires pressurization, for example, in the production of paper-based phenolic resin copper clad boards, adhesive-coated electrolytic copper foil with a phenol-modified butyl rubber adhesive baked into the B state is used. However, in the continuous manufacturing method, rather than using a commercially available metal foil with adhesive, as in the apparatus shown in FIG.
In the configuration in which 0 is laminated, productivity and productivity are improved by continuously supplying an appropriate adhesive stored in the adhesive tank 27 between the laminated base material and the metal foil using the adhesive supply device 28. It was found to be favorable in terms of quality. More preferably, it is applied to the metal foil immediately before lamination, followed by a suitable heat treatment of the intermediate film. In order to effectively achieve adhesion between the metal foil and the resin-impregnated substrate, the adhesive must not contain components that should be removed, such as solvents, and must not generate unnecessary reaction by-products during the curing process. Adhesives that are liquid or semi-liquid, ie, have a viscosity of preferably 5000 poise or less, are suitable. From this viewpoint, for example, unsaturated polyester adhesives, epoxy resin adhesives, polyisocyanate adhesives, or various modified adhesives thereof are suitable. By introducing such an adhesive, it is possible to continuously produce a metal foil-clad laminate that has excellent adhesive strength of metal foil, and excellent solder heat resistance and electrical insulation properties. The method of supplying between the metal foil and the laminate may be by coating the metal foil immediately before laminating the metal foil, or by coating the surface of the laminate.
The metal foil may be laminated or may be injected into the bonding surface during lamination. However, in the above method, depending on the method of supplying the adhesive, air bubbles may be introduced into the interior, and certain combinations of resin liquid and adhesive may cause abnormal curing or classification of the mixture. There were cases where the yield and quality were reduced. Therefore, the present invention also proposes a further improved method. Immediately before laminating the metal foil 10 drawn out from the metal foil supply device 11, the sixth
As shown in the figure, an adhesive coating device 25 and an adhesive heat treatment device 26 are arranged, and a process of continuously applying an adhesive to metal foil and heat-treating the coating film is added. As the adhesive coating device 25, a normal roll coater, blade coater, wire bar coater, comma coater, etc. can be used. The first purpose of heat treating a coating film is to dry the solvent when a solution-based adhesive is used, and in the present invention, it is not necessary that the coating film be non-tacky after drying as in conventional methods. The second purpose is to control the degree of cure of the thermosetting adhesive during lamination. At this time, it is not preferable to advance the curing too much, and it is generally best to control the curing to an extent that it has some tackiness. The third purpose is that, especially when using a two-component mixed type epoxy resin adhesive, the viscosity of this adhesive is relatively high, and therefore air bubbles may be introduced during mixing, resulting in the coating film containing air bubbles. This can be removed by such heat treatment. Below, we will explain a paper-based copper-clad laminate using an unsaturated polyester resin and an epoxy adhesive as an example. As the adhesive, a mixture of a bisphenol A type epoxy resin and a polyamide resin is suitable. be. The paper unwound from the paper unwinding reel comes into contact with a resin liquid in an impregnating bath and becomes resin-impregnated paper. For example, seven sheets of resin-impregnated paper are stacked on top of each other using a stacking device 3 consisting of a pair of rolls. Electrolytic copper foil is then laminated onto the combined material. The foil is coated with adhesive as described above. When using epoxy adhesive, heat treatment is 100%
It is best to do this at a temperature of ~150°C for about 2 to 7 minutes.
It may be cooled to room temperature during lamination. At this time, it is best to perform heat treatment to the extent that some stickiness remains when touched with the finger. If it is completely dry to the touch, the adhesion with the paper impregnated with polyester resin will be impaired, and if it is too tacky, there will be a large amount of mixing of the resin liquid and adhesive during the subsequent curing process, and in some cases, the adhesive will performance may deteriorate. The thickness of the adhesive coating may be about 10 to 100 μm, and preferably about 20 to 40 μm. Then, it is transported to the curing furnace 4. At this time, if necessary, a cover film such as cellophane or polyester film is laminated on the opposite side of the surface to which the metal foil is bonded. It is also possible to use metal foil instead of the cover film to produce a double-sided metal foil laminate. Curing conditions must be selected in accordance with the catalyst, conveyance speed, etc., and, for example, 100° C. for 1 hour is good. By using the above method, the peel strength of copper foil can be increased.
Copper-clad laminates of XP to XXXPC (Triex PC) according to the NEMA standard, which is 1.6 to 2.0 Kg/cm, can be manufactured with excellent productivity. As described above, the present invention has made possible the continuous production of metal foil-clad laminates, which has not yet been put into practical use industrially. The thermosetting resin liquid to be impregnated into the base material is preferably liquid at room temperature, but is not limited thereto, and any resin that is solid at room temperature but becomes liquid when heated can be used for the purpose of the present invention. Of course. Next, an example will be described in which the adhesive effect of the present invention is further improved. When using an unsaturated polyester resin and an epoxy resin as an adhesive, it is preferable to use an amine-curing epoxy resin from the viewpoint of matching the curing speed of both. Rather than using peroxydicarbonates, ketone peroxides, hydroperoxides, or diacyl peroxides as peroxides,
Use of one or more peroxides selected from peroxyketals, dialkyl peroxides, and peroxyesters provides particularly favorable results in terms of solder heat resistance, electrical insulation properties, and adhesive properties. A good blending amount is about 0.5 to 2.0 parts based on the resin liquid. The reason for this has not been fully elucidated by the inventors, but in general, solder heat resistance, electrical insulation properties, and adhesive properties depend on the properties of the cured adhesive. It can be assumed that during the curing process, peroxide diffuses into the adhesive layer or mixes the resin liquid and adhesive, and peroxydicarbonates, ketone peroxides, hydroperoxides, or When diacyl peroxides are used, it is thought that these substances may cause abnormal curing of the epoxy resin, and the resulting cured product may not have sufficient properties. Therefore, preferred catalysts include peroxyketals such as 1-1-bis(t-butylperoxy)3.3.5-trimethylcyclohexane,
1-1-bis(t-butylperoxy)cyclohexane, n-butyl-4.4-bis(t-butylperoxy)valerate, dialkyl peroxides such as di-t-butylperoxide, 2.5-dimethyl-2.5 -di(t-butylperoxy)hexyne-3, as peroxy esters, for example, t-butylperoxyacetate, t
-Butylperoxy 2-ethylhexanoate,
These include t-butyl peroxylaurate and t-butyl peroxybenzoate. The unsaturated polyester may be a well-known one synthesized from an unsaturated dibasic acid, a saturated dibasic acid and a glycol, a bisphenol A type polyester resin, or a vinyl ester type resin. Styrene is commonly used as a crosslinking monomer and is also suitable for the present invention. As the epoxy resin, bisphenol A type is suitable, and as the amine curing agent, any well-known ones such as aliphatic amines and aromatic amines can be used. Furthermore, polyamide resins, amino-terminated polybutadiene nitrile rubber, etc. may also be used as this type of curing agent. Alternatively, a mixture of the above curing agents may be used. By carefully implementing the method described above, it is possible to efficiently produce a metal foil-clad laminate with excellent performance. By interposing a compound having both an unsaturated double bond and an epoxy group such as glycidyl methacrylate, glycidyl allyl ether, partially epoxidized soybean oil, etc., the unsaturated polyester resin layer and the epoxy resin layer can be separated. The affinity is further improved, and it is effective in suppressing the occurrence of defective products due to peeling at the interface caused by fluctuations in manufacturing conditions. In addition, when impregnating the base material with epoxy resin, especially when the base material is a commercially available glass cloth surface-treated for epoxy resin and a commercially available electrolytic copper foil for printed circuits is used, the epoxy resin is a copper foil. Since the adhesion with the copper foil is good, it is possible to obtain a product with excellent adhesion strength to the copper foil without introducing the above-mentioned adhesive. When the substrate is impregnated with unsaturated polyester resin or epoxy resin, better results can be obtained by applying a surface treatment agent, especially a silane coupling agent, to the surface of the copper foil. This surface treatment agent is applied prior to applying an adhesive to the surface of the metal foil. Any silane coupling agent that is generally used for joining surfaces between inorganic and organic substances can be used, but Union Carbide A-
1100 and A-187 were suitable. It is preferable to continuously apply a 0.1-1% alcohol solution or aqueous solution of the silane coupling agent to the metal foil, and then dry it continuously. In the present invention, regardless of whether or not a surface treatment agent is used, the metal foil is passed through a hot air oven and heated to 100°C.
It is best to dry it with hot air for a few minutes. The substrate is also dried at 100° C. for a few minutes to 20 minutes in a hot air or steam heated cylinder just before the impregnation step. Drying removes adhering moisture and improves adhesion with adhesives and resins. In order to minimize warping, twisting, and other deformations of the product, we have arrived at the following invention. Generally, curable resins shrink in volume as they harden, causing residual strain inside the resin and warping or twisting of the product. Furthermore, if the resin has not completely cured, new warping or twisting will occur if the product is subsequently placed in a heated environment. Incomplete curing also significantly reduces heat resistance, chemical resistance, and mechanical properties. In addition, if the resin has not completely cured, if the product is subsequently placed in a heated environment, not only will new warpage and twisting occur, but incomplete curing may cause problems with heat resistance, Chemical resistance, mechanical properties and properties are significantly reduced. According to research conducted by the present inventors, there is a problem in that when continuously manufacturing a laminate, an extremely large curing device or extremely slow line speed is required in order to complete curing. In the present invention, the laminate is cut at a stage where the curing has progressed to a certain extent, and then the cut pieces are stacked in multiple layers and placed in a heating chamber to proceed with curing. curing can proceed at the same time. Therefore, it is sufficient to cure the laminate in the continuous manufacturing process to a state where the laminate can be sufficiently cut with a guillotine cutter and the laminated coating can be peeled off without any problem. As a result, it has become possible to manufacture laminates using economical and practical curing equipment and line speeds. For example, when using unsaturated polyester resin, even if it normally takes 10 hours at 100℃ to fully cure, it is possible to cut it.
About 15 minutes is sufficient. Residual strain due to curing shrinkage of the resin layer can be relatively easily removed by releasing it as warp in the width direction, but residual strain in the longitudinal direction cannot usually be removed because the resin layer is a long body. Therefore, anisotropy occurs in the residual strain in the vertical and horizontal directions of the product. This causes increased warpage and twisting when the product is subsequently placed in a heated environment. In the present invention, since curing is further advanced after cutting, warping and residual strain can be made isotropic to a practically acceptable degree during the curing process. The size of warp in a metal foil-clad laminate varies depending on the resin used, and is generally small for epoxy resins and large for unsaturated polyester resins and diallyl phthalate resins. Furthermore, even if the resin is of the same type, the composition varies depending on the composition. For example, a 1.6 mm thick laminate made of unsaturated polyester resin and paper and covered with 35 μm thick copper foil has a warping amount in the range of about 0.5 to 30% as defined in JIS C-6481. However, after cutting the above-mentioned continuous body, it is necessary to proceed with curing at a temperature higher than the temperature of the continuous heat curing furnace, or at a temperature equivalent to the environment to which the product will be exposed in practice, and then mechanically correct the warpage. This made it possible to make it substantially flat. It has been found that this product significantly reduces warpage that occurs in the product in practical use, for example, in a heated environment. The apparatus shown in FIG. 5 is used in the continuous production of laminates.
A second curing device 29 is installed downstream of the cutting device 5, and the laminate 7 is placed on a conveyance device 30 that passes through the device 29, and is cured for a short time at 150° C. for 15 minutes. Two warpage correction devices 31, 31 and a turntable 32 are arranged at the exit. After the long laminate 7 is cut into practical dimensions, it enters the second curing device 29 and is treated at a higher temperature than the curing conditions of the continuous thermosetting furnace 4 for a short period of time, e.g. , 31 are passed. The laminate 7 passes in two directions, vertically and horizontally, between three adjacent rollers provided in the warpage correction device, and warpage is mechanically corrected. In order to obtain high productivity, the coating is not only applied to the upper and lower surfaces of the laminated base material impregnated with resin liquid, but also one or several layers are sandwiched between the layers, and after curing, the intermediate coating is used as the boundary. By separating the layers into upper and lower layers, a large number of laminates could be manufactured at the same time. Since the drying time, impregnating time, and curing time described above in the present invention hardly change, productivity has been dramatically improved. It has been found that the coating plays the role of a separator when the base material is layered in multiple stages. Therefore, the base material can be laminated on both sides of the coating, and the lamination of the coating and the base material can be repeated in multiple stages. If the coating is a metal foil, it can be peeled off after molding, and by adhering the metal foil to either side of the laminate, a single-sided metal foil-clad laminate and a double-sided metal foil-clad laminate can be separated. get at the same time. In this case, if necessary, an adhesive is applied in advance to one side of the metal foil. As an example of implementation, when manufacturing a 35 μm thick copper foil laminate with a thickness of 1.6 mm by laminating paper base materials impregnated with unsaturated polyester resin, the paper base impregnated with unsaturated polyester resin Layer, for example, pre-dried cellophane between the materials,
By laminating base materials of a predetermined thickness on the top and bottom, applying copper foil as a cover film, and laminating, it is possible to simultaneously manufacture two laminates with copper foil on one side, which is a normal continuous manufacturing process. Achieved twice the productivity compared to the conventional method. According to the present invention, products of various types having different thicknesses can be laminated with the coating as a boundary and manufactured simultaneously, which is advantageous in preventing a decrease in productivity due to switching of products. As described above, the present invention dramatically improves the productivity of laminates in a continuous manufacturing method, but compared to manufacturing in a single layer, especially when curing or cutting into practical dimensions, Since the overall thickness of the body is thick, conditions such as heating efficiency during curing, heat transfer of curing reaction heat, heat radiation, etc. change, so consideration is required. A heating furnace that can precisely control heating, heat generation, heat transfer, and heat radiation depending on the number of stages is used, for example, a furnace whose interior is divided into several blocks and whose temperature can be controlled appropriately. In addition, when using a catalyst and a curing agent for unsaturated polyester resin, in consideration of the heat generated during the curing reaction, the impregnated resin liquid of the impregnated substrate located on the outside should be It is desirable to impregnate the resin liquid with a reduced amount of catalyst, etc. If the thickness is difficult to cut with a guillotine cutter, it is best to install a movable slicer to cut it. Next, we will describe the circumstances in which the present invention was implemented under various manufacturing conditions. The characteristics of the products manufactured in each example are as follows:
They are listed together in Table 7. Example 1 The manufacturing apparatus shown in FIG. 4 was used. The unsaturated polyester resin liquid is made from maleic acid, isophthalic acid, and ethylene glycol, with a molar ratio of 82:18:
Styrene was added as a polymerizable monomer to an unsaturated polyester synthesized by a conventional method to give a
% by weight to obtain a product with a viscosity of 5 poise at 25°C. To 100 parts by weight of this product, 1 part by weight of cumene hydroperoxide as a curing catalyst and 0.2 parts by weight of a 6% cobalt naphthenate solution as a curing aid were blended to obtain an unsaturated polyester resin liquid composition. The properties of this cured resin liquid composition were as shown in Table 2.

[Table] Commercially available kraft paper mainly composed of cellulose fibers shown in Table 3 was used as the sheet-like base material.

【table】

【table】

[Table] Note that the polyester film was peeled off using a coating stripping device 24 consisting of a pair of rolls, and wound up using a coating winding device. Immediately after adjusting the spacing of the laminating rollers and laminating the polyester film,
The weight ratio of resin liquid to two sheets of impregnated paper base material is approximately
I set it to 55%. In this way, finally, a laminate having a thickness of 0.50 mm and external dimensions of 1020 mm x 1020 mm was continuously produced. The laminate was subjected to an alkali resistance test by immersing it in a 5% caustic soda aqueous solution at 40° C. for 30 minutes, and a solvent resistance test by immersing it in boiling toluene for 2 minutes, but no abnormalities were found in all the examples. Example 2 In Example 1, a hot air dryer was operated as the substrate dryer 12, and the paper base material was continuously passed through the hot air dryer at 100° C. for 10 minutes. Other conditions are the same as in Example 1. Example 3 In Example 2, the number of continuously conveyed paper base materials was set to 5, and a laminate having a thickness of 1.5 mm was manufactured. The spacing between the laminating rollers was adjusted so that the weight ratio of the resin liquid to the five impregnated paper substrates was approximately 60%. Example 4 In Example 3, commercially available Rigorak 150HRN (manufactured by Showa Kobunshi) was used as the unsaturated polyester resin liquid. The glass transition temperature of the cured product is
It was 120℃. Example 5 In Example 3, the unsaturated polyester was changed to the following. That is, using maleic acid, isophthalic acid, and diethylene glycol as raw materials, an unsaturated polyester resin was synthesized by a conventional method so that the molar ratio of each was 32:68:100, and styrene was added at 37% by weight. Mixed. This resin liquid has a viscosity of 4.5 poise at 25°C and is a liquid unsaturated polyester resin at room temperature. Note that the glass transition temperature of the cured product obtained from this resin liquid was about 55°C. Examples 6, 7, 8 The dip impregnation method employed in Examples 3, 4, and 5 was changed to a single-sided impregnation method using the so-called curtain flow method, in which the resin liquid was allowed to flow down from above the paper base material. As a result, there were almost no microscopic bubbles in the product compared to Examples 1 to 5.
A product with even better cylinder heat resistance was obtained. In addition, the test results of the products were equivalent to the results of Examples 3, 4, and 5, respectively. Example 9 10 and 11 Example 6 In Examples 7 and 8, the resin liquid was previously treated under reduced pressure and the impregnation time was shortened to 4 minutes. An example of depressurization treatment is shown in Figure 1, where resin liquid is jetted into the air at a rate of 10/min from above a sealable cylindrical container with an inner diameter of 30 cm and a height of 100 cm, so that the pressure inside the container is constantly maintained. It was adjusted to 20 mmHg. This resin liquid treated under reduced pressure was extracted from the lower part of the cylindrical container using a pump and supplied above the paper base material. There were almost no air bubbles in the product, and the product properties were the same as those of Examples 3, 4, and 5, respectively, even though the impregnation time was significantly shortened. Example 12 13 and 14 In Examples 3, 4 and 5, the cumene hydroperoxide used as the curing catalyst was changed to t-butyl peroxy-2-ethylhexanoate, which is an aliphatic peroxy ester. did. With this product, the odor generated under heating conditions of 180℃ for 30 minutes was significantly reduced. The laminate obtained after curing was cut and heat-treated in a hot air oven at 100° C. for 10 hours to further promote curing. This laminate had stable qualities such as solder heat resistance, dimensional stability, and insulation properties. Example 15 Unsaturated polyester resin composition used in Example 14 (unsaturated polyester resin synthesized in Example 5)
In Examples 9, 10 and 11, using 1 part by weight of t-butylperoxy-2-ethylhexanoate shown in Example 14 and 0.2 parts by weight of 6% cobalt naphthenate per 100 parts by weight. The vacuum treatment and impregnation methods shown were applied. Impregnation time 5 minutes, curing temperature 100
℃, and the conveyance speed of the substrate was tripled so that the curing time was 22.5 minutes. Other manufacturing conditions were the same as in Example 1. After a curing time of 22.5 minutes, it was cut to obtain a laminate, but the curing was insufficient at this curing time and the quality was not sufficient. After cutting, the pieces were placed in a hot air oven at 100° for 10 hours to further harden them.
By adding a heat treatment step at 160°C for 10 minutes, a product with particularly good solder heat resistance and heat shrinkage was obtained. By simply providing a separate hot air stove and adding a heat treatment process after cutting, the production efficiency of the apparatus of Example 1 was quadrupled at once. Example 16 The paper base material of Example 1 was subjected to the following pre-impregnation treatment. A long piece of paper is coated with N-methylol acrylamide.
% methanol solution for 5 minutes and then taken out, approx.
A continuous process of air drying for 30 minutes and heating drying at 100° C. for 20 minutes was performed to obtain a long N-methylolacrylamide treated paper. At this time, the amount of N-methylol acrylamide attached to the paper was 11.2%.
It was hot. We prepared five rolls of the long treated paper mentioned above, and while conveying them individually and continuously,
A laminate with a thickness of 1.5 mm was obtained in the same manner as in Example 15. Compared to Example 15, the properties are markedly improved in solder heat resistance and electrical properties during moisture absorption treatment. Example 17 In Example 16, the covering film followed the unevenness of the paper base material, and gentle undulations were observed on the surface. In Example 16, this coating was
It was manufactured by changing to a long stainless steel foil (material SUS304) with a so-called BA surface finish of 100 μm. The surface roughness of this stainless steel foil was Rmax = 2.5 microns, and the rigidity value = 1.86 kg·cm. In the product, the above-mentioned undulations disappeared, the surface smoothness was evaluated as excellent, and the surface appearance, printability of foreign resists and pastes, and transferability of these inks were satisfactory. Example 18 The paper substrate described in Example 1 was subjected to the following pre-impregnation treatment. That is, in 50 parts by weight of methanol in which 1.5 parts by weight of oleic acid monoglyceride (Riken Vitamin Oil Rikemar OL-100) was dissolved, methylol melamine (Nippon Carbide Industries, Ltd., Nikaresin S-) was added.
305) A turbid treatment liquid was prepared by pouring 50 parts by weight of water in which 6 parts by weight was dissolved while stirring strongly.
The above-mentioned long paper is continuously immersed in this treatment liquid,
After being taken out, the long treated paper base material was heat-dried at 120° C. for 20 minutes and wound into a roll. In Example 17,
Change the long treated paper to the one above to reduce the thickness.
A 1.5 mm laminate was obtained. Product characteristics are shown in Table 7. This table was approximately the same as the characteristics of the product of Example 17. Example 19 In Example 18, a laminate was produced by laminating stainless steel foil on both sides of a base material impregnated with a resin liquid, and peeling off the foil after curing. / ft ² electrolytic copper foil (manufactured by Fukuda Metal Foil & Powder Industries, T-7). After curing, this electrolytic copper foil was not peeled off, but only the stainless steel foil on the opposite side was peeled off to form a copper foil-clad laminate. Obtained. Other conditions were the same as in Example 18. Example 20 The product of Example 19 has the disadvantage of a large amount of warpage.
Therefore, as shown in the apparatus shown in FIG. 5, a warping process was added, and the gap between the three rolls was adjusted and corrected, thereby greatly improving the amount of warpage. Example 21 In order to improve the copper foil adhesive strength and solder heat resistance test results of the product obtained in Example 19, Example 19 was
Before laminating a long electrolytic copper foil,
As in the apparatus shown in FIG. 6, a step of coating with adhesive was added. The adhesive has the formulation shown in Table 5. The coating thickness on the copper foil was 60 μm.

[Table] The peel strength of the product's electrolytic copper foil satisfies JIS standards. Example 22 In Example 21, immediately after coating the electrolytic copper foil with the adhesive using the apparatus shown in FIG. 6, the electrolytic copper foil was passed through a heat treatment apparatus, and a heat treatment step was added at 100°C for 5 minutes. A single-sided copper foil plate was manufactured. The properties of solder heat resistance and peel strength of electrolytic copper foil have been improved. Example 23 The curing catalyst of Example 23 was replaced with 1-1-bis(t-butylperoxy), which is a peroxyketal.
3.3.5-Trimethylcyclohexane was used. The characteristics of the product are when absorbing heat (conditions are C-96/55/
95) solder heat resistance improved to 10 to 27 seconds. Other properties were the same as in Example 22. Example 24 An experiment was conducted in which a curing aid was not added to Example 23. The characteristics of the product were the same as in Example 23. Example 25 In Example 23, a silane coupling agent (ucc) was applied before coating the adhesive onto the electrolytic copper foil.
A-187) A process of continuously applying an aqueous solution containing 0.5% by weight to a thickness of approximately 10 μm on the surface of electrolytic copper foil, followed by a process of drying at 100°C for 2 minutes to produce a single-sided copper-clad board. was manufactured. In particular, solder heat resistance and electrolytic copper foil peel strength were improved. Example 26 Commercially available long glass cloth (WE18K manufactured by Nittobo Co., Ltd.)
First, while conveying 8 sheets (ZB) continuously, 100
The epoxy resin composition shown in Table 6, which is liquid at room temperature, was dried continuously at 10°C for 10 minutes, and then treated under reduced pressure in the same manner as in Examples 9, 10, and 11 (viscosity: 6.5 at 25°C). Poise) was allowed to flow down from above the glass cloth using a curtain flow method.

[Table] Impregnation time 10 minutes. Laminate 8 glass cloths and apply silane coupling agent (UCC-A-) to both sides in advance.
1100) coated with commercially available electrolytic copper foil (Fukuda Kinzoku T)
-7) were laminated continuously. The spacing between the laminating rollers was adjusted so that the weight ratio of the resin liquid to the impregnated base material was approximately 58%. Then, it was continuously cured at 130℃ for 60 minutes.
It was cut and then further heat treated at 180°C for 2 hours to obtain a product with external dimensions of 1020 mm x 1020 mm and a thickness of 1.6 mm. An excellent laminate with good balance in all properties was obtained.

【table】

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an outline of an apparatus used to implement the present invention. FIG. 2 is a cross-sectional view of a product using a coating with low rigidity. FIG. 3 is a cross-sectional view of a product using a highly rigid coating. FIGS. 4 to 6 are explanatory diagrams showing other examples of devices used to implement the present invention. DESCRIPTION OF SYMBOLS 1... Base material supply part, 2... Impregnation device, 3... Lamination device, 4... Continuous heating furnace, 6... Base material, 7...
Laminate, 10... Covering, 23... Laminating device.

Claims (1)

[Scope of Claims] 1. A thermosetting resin liquid that is liquid at room temperature and which essentially does not require a drying process and generates almost no reaction by-products such as gas or liquid during the curing reaction process is treated under reduced pressure in advance. After that, a step of individually impregnating and adhering the resin liquid to each sheet-like substrate using an impregnating device provided for each sheet-like substrate, and impregnating while continuously conveying a plurality of resin liquid-impregnated substrates in a state where they are individually separated. A step of laminating a film-like or sheet-like coating on both sides of the laminated base material simultaneously with or after laminating a plurality of the resin liquid-impregnated base materials; Method A of either or both of the following methods A and B: The thermosetting resin liquid to be impregnated into the base material is preliminarily applied in excess. A method for removing excess resin liquid when and/or before laminating a sheet-like coating on a laminated base material of the impregnated base material. B. When laminating resin liquid-impregnated base materials and/or when laminating sheet-like coverings on both sides of the laminated base material, the coating is laminated by a method of newly supplying the thermosetting resin liquid. The amount of resin liquid contained in the resin liquid-impregnated laminated base material after the resin liquid-impregnated laminated base material is adjusted to a desired specific amount within the range of 30 to 80% by weight based on the resin liquid-impregnated laminated base material, and the resin liquid-impregnated laminated base material is cured. 1. A continuous manufacturing method for electrical rigid laminates, characterized in that when the sheet-like coating is not adhered to the surface of the laminate substrate, the strength is at least such that it can be peeled off from the surface of the laminate substrate without any hindrance. 2. A patent claim characterized in that one or both of the film-like or sheet-like coverings is metal foil, and after the impregnating resin liquid has hardened, one or both of the coverings is used as a metal foil-clad laminate without being peeled off. A method for continuous production of a laminate according to scope 1. 3. The continuous manufacturing method of a laminate according to claim 2, wherein the metal foil is an electrolytic copper foil for printed circuits. 4. The method for continuously manufacturing a laminate as defined in any one of claims 1 to 3, wherein the thermosetting resin is an unsaturated polyester resin that is liquid at room temperature. 5. The method for continuously manufacturing a laminate as defined in any one of claims 1 to 3, wherein the thermosetting resin is an epoxy resin that is liquid at room temperature. 6. A method for continuously manufacturing a laminate as defined in any one of claims 1 to 3, wherein the sheet-like base material is cellulose-based. 7. A method for continuously producing a laminate as defined in any one of claims 1 to 3, wherein the sheet-like base material is made of glass fiber. 8. According to any one of claims 1 to 3, the sheet-like material is impregnated with a pre-impregnating liquid before impregnating with the resin liquid, and the pre-impregnated base material is dried as necessary. Specified continuous manufacturing method for laminates. 9 The sheet-like base material is cellulose-based, the thermosetting resin is an unsaturated polyester resin that is liquid at room temperature, and the pre-impregnation liquid is an N-methylol compound having an unsaturated bond that can be copolymerized with a polymerization monomer. 9. A method for continuously manufacturing a laminate according to claim 8, which comprises: 10. The continuous production method of a laminate according to claim 9, wherein the N-methylol compound is a modified aminotriazine methylol compound. 11 N-methylol compound has the general formula (However, _R1 is H or _CH2 , _R2 is H or a _C1-3 alkyl group.) The method for continuously producing a laminate according to claim 9, wherein R1 is H or CH2, and R2 is H or a _C1-3 alkyl group. 12 The sheet-like base material is cellulose-based, the thermosetting resin is an unsaturated polyester resin that is liquid at room temperature, and the pre-impregnation liquid is N-methylol that does not have unsaturated bonds that can be copolymerized with the polymerization monomer. Claim 8 includes a polyfunctional compound that has a compound, a) a functional group that can be condensed with or added to the N-methylol compound, and b) an unsaturated bond that is copolymerizable with a polymerizable monomer. A continuous manufacturing method for a laminate. 13 The sheet-like base material is cellulose-based, the thermosetting resin is an unsaturated polyester resin that is liquid at room temperature, and the pre-impregnating liquid is A, which is a mixture of A and B or a condensation product of A and B. Methylolmelamine and/or methylolguanamine B A higher aliphatic derivative having at least one group capable of bonding to a methylol group in the molecule A method for continuously producing a laminate according to claim 8. 14 Groups that can be condensed with a methylol group include a hydroxyl group,
14. The continuous production method of a laminate according to claim 13, wherein the group is selected from the group consisting of a carboxyl group, an amino group, and an amide group. 15 Higher fat derivatives include oleyl alcohol,
14. The method for continuously producing a laminate according to claim 13, wherein the laminate is one or a mixture of two or more selected from the group consisting of oleic acid, oleic monoglyceride, oleic diglyceride, oleamide, and oleylamine. 16 After dipping the mixture or condensation product of the N-methylol compound and higher aliphatic derivative onto the sheet-like substrate and drying, the total amount of the mixture attached to the substrate is 3 to 3.
14. The method for continuously producing a laminate according to claim 13, wherein the amount is 30 parts by weight. 17. Claim 6 or 9, wherein the sheet-like base material is paper mainly composed of cellulose fibers.
A method for continuously manufacturing a laminate as defined in any of Items 1 to 16. 18. The continuous production method of a laminate as defined in claim 4 or any one of claims 9 to 16, wherein the curing catalyst is an aliphatic peroxide. 19. The continuous production method of a laminate according to claim 18, wherein the aliphatic peroxide is an aliphatic peroxyester. 20 The polymerizable monomer used for crosslinking the thermosetting resin is styrene and/or styrene derivatives, or a mixture of these and divinylbenzel. A method for continuously producing a laminate as defined in any of Item 16. 21 The thermosetting resin is an unsaturated polyester resin that is liquid at room temperature, and the cured product thereof has a glass transition temperature of 20 to 80°C. Claims 1 to 3 and 9 to 17 A continuous manufacturing method for a laminate as specified in any of the following. 22 The sheet-like base material is impregnated using a single-sided impregnation method in which the resin liquid flows down from above the base material. Continuous manufacturing method. 23 The rigidity value of a film-like or sheet-like covering is E・d ³ (E is the bending elastic modulus Kg/cm ² and d is the thickness cm)
A method for continuously producing a laminate as defined in any one of claims 1 to 3 and 9 to 17, wherein the weight is 3×10 ^-3 Kg·cm or more. 24. A laminate as defined in any one of claims 1 to 3 or 23, in which the surface roughness of the film-like or sheet-like coating is approximately 0.4 microns or more and approximately 5 microns or less when expressed as Rmax. continuous manufacturing method. 25 Claims 2, 3, and 9 to 17, in which the metal foil is laminated by continuously supplying an adhesive between the metal foil and the base material impregnated with a resin liquid.
Continuous manufacturing method for laminates specified in any of the following paragraphs. 26. The continuous production method of a laminate according to claim 25, wherein the adhesive is supplied by continuously applying it to the surface of the metal foil before laminating the metal foil. 27. The continuous production method of a laminate according to claim 26, wherein the metal foil coated with the adhesive is subjected to a coating film heat treatment step before being laminated. 28 The adhesive does not substantially contain components removed by drying such as solvents, and does not substantially generate gaseous or liquid reaction by-products during the curing reaction process of the adhesive; 26. The continuous production method of a laminate according to claim 25, wherein the molding pressure is substantially no pressure when the resin liquid-impregnated laminate substrate is adhered to the resin liquid-impregnated laminate substrate and cured together. 29 The thermosetting resin liquid is an unsaturated polyester resin that is liquid at room temperature, the adhesive is an amine-oxidized epoxy resin, and peroxyketal,
Claims 25 to 2 use one or more peroxides selected from the group of peroxyesters or dialkyl peroxides.
A method for continuous production of a laminate as specified in any of Clause 8. 30 Claim 25, in which a compound having both a copolymerizable unsaturated double bond and an epoxy group is interposed near the joint between the resin liquid-impregnated laminated base material and the adhesive applied to the metal foil and then cured. The method prescribed in any of paragraphs 28 to 28. 31. The method according to claim 25, wherein the metal foil undergoes a step of continuously drying adhering moisture before applying the adhesive. 32. The method according to claim 25, wherein the metal foil passes through a step of continuously applying a surface treatment agent before the drying step. 33. The method according to claim 32, wherein the surface treatment is a silane coupling agent. 34. The method according to claim 1, wherein the pressure reduction treatment is performed by squirting the resin liquid into a container whose pressure is reduced to 30 mmHg or less and accumulating it at the bottom of the container. 35. The method defined in any one of claims 1 to 3 and 9 to 16, wherein the elongated laminate is cut into practical dimensions during curing and further cured after cutting. 36 Film-like or sheet-like coverings are laminated in multiple stages on both sides of the resin liquid-impregnated laminated base material and sandwiched between the resin liquid-impregnated base materials, cured, and then cut with the intermediate coating as the boundary. A method according to any one of claims 1 to 3, in which a laminate is separated into upper and lower parts and a large number of laminates are obtained at the same time. 37. The method defined in any one of claims 1 to 3, wherein the coating passes through a step of continuously applying a mold release agent to the entire surface or both edges. 38 Claims 1 to 3 in which the coating is continuously peeled off, rolled up and collected after the laminate is cured.
The method prescribed in any of the paragraphs. 39. The method defined in any one of claims 1 to 3, wherein the coating is an endless belt and is continuously peeled off after the laminate is cured. 40 The weight ratio of the resin liquid amount of the resin liquid impregnated base material is:
The method according to claim 1, wherein the amount is 30 to 70% based on the impregnated substrate.