JPS6326133B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a resin-impregnated sheet for producing a laminate, a so-called prepreg. To manufacture laminates using thermosetting resins,
The resin is dissolved in a solvent or monomer to form a varnish-like resin liquid (sometimes called resin varnish), which is impregnated into a base material, heated and dried, and the resin is B-staged to form a prepreg, which is then used as required. This method involves stacking a number of sheets, press-molding them under heat, and curing them. By the way, the process of impregnating the base material with resin liquid is an extremely important process, and if the impregnation state is insufficient, the performance of the product laminate (water absorption rate, insulation resistance, etc.) will deteriorate, so impregnation is necessary. Sufficient care was required in setting the conditions. The manufacturing method of prepreg that has been widely used in the past is
The impregnation of the resin liquid into the base material relied solely on the penetrating power of the resin liquid itself. Therefore, in conventional methods, if the concentration of the resin liquid is high, impregnation does not proceed well, and a large amount of solvent must be used to prepare the resin liquid, which makes exhaust gas treatment difficult in the subsequent drying process. was. In view of the above circumstances, the inventors conducted various studies to establish a method that can efficiently perform impregnation even when using a highly concentrated resin liquid, and as a result, they found that the resin liquid can be retained. The present invention was completed based on the discovery that impregnation of the resin liquid into the base material can be significantly accelerated by exposing the base material to appropriately heated steam. That is, in the present invention, after a resin-retaining base material is obtained by retaining a resin liquid containing a thermosetting resin as a main component, the resin-retaining base material is heated and dried to obtain a prepreg. After obtaining a resin holding base material using a non-volatile content of 60% by weight or more,
A prepreg manufacturing method characterized by exposing this resin-retaining base material to heated solvent vapor and then heating and drying it. The base materials used in this manufacturing method are:
There are various sheet materials such as paper, cloth, glass cloth, synthetic fiber cloth, mat, mixed paper, glass nonwoven fabric, and synthetic fiber nonwoven fabric. Examples of resin liquids mainly composed of thermosetting resins include epoxy resins, unsaturated polyester resins, polyimide resins, alkyd resins,
There are thermosetting resins such as diallyl phthalate resin, phenolic resin, and amino resin, or modified products thereof dissolved in a suitable solvent. Even if no particular solvent is added, these resins may contain monomers and the monomers may serve as a solvent. Any resin that exhibits a liquid state can be used as is. Furthermore, in the case of an epoxy resin, it may contain a so-called diluent, and the diluent may serve as a solvent.
Solvents for dissolving the resin include water, methanol, ethanol, propyl alcohol, butyl alcohol, acetone, methyl ethyl ketone, methyl cellosolve, butyl cellosolve, dioxane,
There are various types such as benzene, toluene, xylene, phenol, and cresol. In some cases, two or more of these solvents may be mixed. If water is selected as the solvent, the resin may not be sufficiently dissolved, resulting in an emulsion, but in some cases, even such an emulsion can be used. be. In this invention, the resin liquid as described above is used, and a high concentration one having a nonvolatile content (resin content) of 60% by weight or more is used. Practically 60-90
% by weight is preferred. Various methods can be used to hold the resin liquid on the base material, such as a roll coater method, a dipping method, and a brush coating method. Here, retention of the resin liquid refers not only to a state in which the resin liquid is merely attached to the surface portion of the base material, but also to a state in which the resin liquid is impregnated inside to a small extent. The resin liquid may be applied to only one side of the base material, or may be applied to both sides. The amount of resin liquid retained in the base material is determined when the resin content of the prepreg after drying is 10 to 60.
A preferable range is % by weight. In this invention, a high concentration resin liquid can be used because the resin liquid is only attached to the surface of the base material or Although the resin liquid has only penetrated into the interior a little, and no substantial impregnation has occurred, when such a resin-retaining base material is exposed to heated solvent vapor, the resin liquid impregnates the base material. This is because the impregnation of the resin liquid is substantially accelerated at this point. Next, the resin holding base material holding the resin liquid is
Exposure to heated solvent vapors. The solvents that are the source of the solvent vapor include those listed above (those with a boiling point of 50°C or higher and 150°C or lower are preferred), and these solvent vapors can be used alone or as a mixed vapor with water vapor. used. The solvent in this case does not need to be the same as the solvent for making the resin liquid. The temperature of the solvent vapor in this solvent vapor treatment is generally the boiling point temperature of the solvent forming the solvent vapor, and the treatment is performed until the temperature of the substrate rises to 50° C. or higher. It goes without saying that the solvent vapor may be accompanied by a gaseous medium at room temperature, such as air. The resin-impregnated base material that has been subjected to the solvent vapor treatment (at this stage, the resin has sufficiently penetrated into the base material) is heat-dried by, for example, hot air drying, infrared radiation heat drying, high-frequency heat drying, or the like. In this way, the desired prepreg can be obtained. FIG. 1 shows an embodiment of an apparatus used for the manufacturing method according to the present invention. In the figure, a base material 1 that has passed through a resin liquid tank 11 becomes a resin holding base material 2 and is sent to a solvent vapor treatment chamber 13 via a squeeze roll 12. Heated solvent vapor is held in the solvent vapor treatment chamber 13, and the resin holding base material 2 is subjected to the solvent vapor treatment here. Through this treatment, impregnation of the resin liquid into the base material rapidly progresses. Further, when the solvent in the resin liquid evaporates, the vapor is led to the solvent recovery device 15 through the vapor exhaust duct 14 together with the solvent vapor for solvent vapor treatment. However, this solvent recovery device 15 is not essential. The resin holding base material 2 leaving the solvent vapor treatment chamber 13 is sent to a drying chamber 16. In the figure, 17
18 is a steam heating erofine for heating the air sucked into the dryer 16, and 18 is an exhaust duct. In the solvent vapor treatment, impregnation of the resin progresses, but in some cases, B-stage conversion of the resin does not progress. In the dryer 16, heating and drying is performed to make the prepreg 3 into a complete prepreg. In this case, since the solvent vapor treatment has been carried out first, drying can be carried out very simply and easily. In FIG. 1, reference numeral 19 denotes a partition wall, which is provided with, for example, a slit-like passage, so that the base material can pass therethrough but the solvent vapor cannot pass therethrough as much as possible. As mentioned above, since drying is easy, the amount of heat required for this is small. As is clear from the above explanation, if this manufacturing method is used, the impregnation state of the resin will be good even if a high concentration resin liquid is used, so the quality of the product will be stabilized and the productivity will improve (conventionally, in some cases, This eliminates the need for repeated impregnation treatments.) Furthermore, since a highly concentrated resin liquid is used, the amount of solvent for preparing the resin liquid can be reduced. Therefore, it is possible to reduce raw material costs and simplify exhaust gas treatment. Next, examples and comparative examples of the present invention will be described. [Example 1] An impregnating resin having the following composition was prepared. Brominated epoxy resin (Epicron 153 manufactured by Dainippon Ink Chemical Industries, Ltd.)
27 parts by weight (hereinafter abbreviated as parts) Chain epoxy resin (Epicron 1600 manufactured by the same company)
10 parts Curing agent Paravinylphenol 10 parts Accelerator Benzyldimethylamine 0.005 parts This impregnating resin was diluted with methyl ethyl ketone to obtain a resin liquid with a resin content of 90% by weight (hereinafter abbreviated as %). Dip-coat this resin liquid onto glass cloth,
Then, as a solvent vapor treatment, it was exposed to water vapor at 100°C for 10 seconds according to the temperature rise curve B in FIG. After that, it was dried to obtain a prepreg with a resin content of 60%. A predetermined number of sheets of this prepreg are stacked together, one sheet of copper foil with adhesive is added with a thickness of 35 μm, sandwiched between metal plates, and molded using a conventional method (molding conditions: 160-170℃, 50Kg/cm ² , 40-90cm) (min.) to create a single-sided copper-clad plate with a thickness of 1.6 mm ± 0.1 mm. [Example 2] An impregnating resin having the following composition was prepared. Bisphenol A type solid epoxy resin (epoxy equivalent: 475) 70 parts Liquid epoxy resin (epoxy equivalent: 180) 18 parts Curing agent: dicyandiamide 4 parts Accelerator: benzyldimethylamine 0.1 part Dilute this impregnating resin with acetone to determine the resin content. It was made into an 85% resin liquid. Hereinafter, a prepreg with a resin content of 60% was obtained in the same manner as in Example 1 above,
A single-sided copper-clad board similar to Example 1 was created. [Example 3] An impregnating resin having the following formulation was prepared. Bisphenol A type epoxy resin (Epicote
828） 37 parts Curing agent Paravinylphenol 10 parts Accelerator Benzyldimethylamine 0.005 parts This impregnating resin (liquid) is used as the resin liquid,
A prepreg with a resin content of 60% was obtained in the same manner as in Example 1, and a single-sided copper-clad board similar to that in Example 1 was produced. [Example 4] The same resin liquid as in Example 1 above was used. Dip-coat this onto glass cloth and use the resulting resin-retaining base material.
When exposed to xylene vapor at 140°C, the substrate temperature was 90°C.
It was processed until it reached ℃. Then, drying was performed to obtain a prepreg with a resin content of 60%. A similar single-sided copper-clad board was created using the obtained prepreg in the same manner as in Example 1. [Example 5] Using the same resin liquid as in Example 2 above, Example 4
A prepreg with a resin content of 60% was obtained in the same manner as above. Using this, a similar single-sided copper-clad board was created in the same manner as in Example 1. [Example 6] The same impregnating resin as in Example 3 above was used as the resin liquid. After dipping this onto glass cloth,
The obtained resin-retaining base material was brought into contact with a mixed vapor of methanol vapor and water vapor at 78°C, and the base material temperature was 70°C.
It was treated until it reached ℃. Then, drying was performed to obtain a prepreg with a resin content of 60%. Using this, a similar single-sided copper-clad board was created in the same manner as in Example 1. [Example 7] A resin liquid with a resin content of 73% was prepared using the following formulation. Unsaturated polyester resin (synthesized from maleic anhydride: phthalic anhydride: isophthalic acid: propylene glycol = 2:1:1:4.3, acid value 28,
(polyester with a softening point of 65°C) 70 parts Diallyl orthophthalate polymer 30 parts tert-butyl perbenzoate 1 part Acetone 37 parts This resin solution was dip-coated on kraft paper with a unit weight of 13.3 g/ ^m2 , and then soaked in steam at 100°C. Then, treatment was carried out for 10 seconds according to curve B in FIG. Then 70°~120
Hot air drying was performed at ℃ to obtain a prepreg with a resin content of 53%. Layer multiple sheets of this prepreg and adhesive-coated copper foil, sandwich them between metal plates, and heat at 150℃ and 100℃.
It was molded under conditions of Kg/cm ² and 30 minutes to obtain a laminate with a thickness of 1.6 mm. [Example 8] A glass cloth was dip-coated with the same resin solution as in Example 7 above, treated in acetone vapor at 56°C for 10 seconds, and then dried with hot air at 70° to 120°C to reduce the resin content to 51. % prepreg was obtained. A plurality of sheets of this prepreg and one sheet of copper foil coated with adhesive were stacked, sandwiched between metal plates, and molded at 140° C. and 20 kg/cm ² for 15 minutes to obtain a laminate with a thickness of 1.6 mm. [Example 9] The following formulation was thoroughly stirred to obtain a resin content of 74.
% resin liquid was obtained. Kelimide #601 (manufactured by Mitsui Petrochemicals) 100 parts N-methylpyrrolidone 35 parts This was dip coated onto a glass cloth treated with aminosilane, and then treated in steam at 100°C for 15 seconds. Then, hot air drying was performed at 150℃,
A prepreg with a resin content of 53% was obtained. Layering multiple sheets of this prepreg and 35 μm thick raw copper foil,
Sandwiched between metal plates, 170℃, 40Kg/cm ² ,
Molding was carried out for 90 minutes, followed by after-curing at 200°C for 60 minutes to obtain a laminate with a thickness of 1.6 mm. [Example 10] Prepreg was prepared in the same manner as in Example 9, except that instead of performing the steam treatment at 100°C for 15 seconds in Example 9, the treatment was performed in dimethylformamide vapor at 150°C for 10 seconds. A similar laminate was obtained. [Example 11] 94 g of phenol (equivalent to 1 mole), 60 g of 80% formaldehyde (equivalent to 1.6 mole), 2 g of magnesium hydroxide, 17.1 g of toluenesulfamide (equivalent to 0.1 mole), and 25 g of water were placed in a three-necked flask with a stirrer. put in,
The reaction was carried out at a temperature of 100°C for 60 minutes. Next, dehydrate and add 30g of methanol to make the resin content 70%.
A resin liquid was obtained. This resin liquid was dip-coated onto kraft paper with a unit weight of 200 g/m ² , and then treated in water vapor at 100°C for 20 seconds according to curve B in Figure 2, and then dried with an infrared heater to reduce the resin content to 35. % phenolic resin impregnated paper was obtained. Next, melamine 126g (equivalent to 1 mol), formaldehyde (55% aqueous solution) 109g (equivalent to 2 mol)
into a three-necked flask and add caustic soda to adjust the pH.
10 and reacted at a temperature of 100°C for 70 minutes to obtain a melamine initial condensate, to which 102.6 g (equivalent to 0.6 mol) of para-toluenesulfamide was added and reacted at 70°C for 30 minutes to form a melamine resin (liquid). Obtained. This was diluted with methanol to obtain a resin liquid with a resin content of 65%. This resin liquid was dip-coated onto patterned paper with a unit weight of 120 g/m ² , and then treated in water vapor at 100°C for 20 seconds according to curve B in Figure 2, and then dried with an infrared heater to reduce the resin content. A patterned paper impregnated with 45% melamine resin was obtained. Five sheets of the phenol resin-impregnated paper obtained as above were stacked, and one sheet of melamine resin-impregnated patterned paper was stacked thereon and molded by a conventional method to obtain a melamine decorative board. [Example 12] The following formulation was thoroughly stirred and the resin content was 67.
% of homogeneous resin liquid was obtained. Diallyl orthophthalate prepolymer 100 parts Diallyl orthophthalate monomer 5 parts tert-butyl perbenzoate 2 parts Internal mold release agent (lauric acid) ³ parts Acetone 50 parts Dip-coated on cellulose paper. The obtained resin-retaining base material was placed in a room adjusted to a temperature of 80°C and a relative humidity of 50%, treated for 10 seconds, and then dried with hot air at a temperature of 70° to 120°C, resulting in a resin content of 62%. prepreg was obtained. This prepreg was placed on a 3.2mm hardboard base plate and pressed at a temperature of 140℃, 15℃.
Pressure molding was carried out for 8 minutes at a pressure of Kg/cm ² to obtain a decorative board. [Comparative Examples 1 to 12] In the examples with the corresponding numbers, the coatings were applied in exactly the same manner as in the corresponding examples, except that after the resin liquid was dip-coated, the solvent vapor treatment was not performed and the coatings were immediately dried. A prepreg was created and a laminate was obtained. When a high concentration resin liquid of 60% by weight or more is used as in this invention, as can be seen from the comparison between Examples 1 to 12 and Comparative Examples 1 to 12, there is a significant difference between exposure to solvent vapor and not exposure. occurs. However, in the case of conventionally used low-concentration resin liquids of less than 60% by weight, a large amount of solvent is used to improve resin impregnation, so substantial resin impregnation has already occurred before exposure to solvent vapor. There is no substantial difference in the performance of the prepreg whether or not it is exposed to solvent vapor. For example, when a laminate is made, its properties hardly change. Comparative example below
Table 3, which shows the performance measurements of the laminates Nos. 13 to 16, illustrates this. [Comparative Example 13] The impregnating resin of Example 1 was further diluted with methyl ethyl ketone to obtain a resin liquid with a resin content of 45% by weight. A single-sided copper-clad board was obtained using this resin liquid in the same manner as in Example 1. [Comparative Example 14] The impregnating resin of Example 1 was further diluted with methyl ethyl ketone to obtain a resin liquid with a resin content of 45% by weight. A single-sided copper-clad board was obtained using this resin liquid in the same manner as in Example 4. [Comparative Example 15] A single-sided copper-clad board was obtained in the same manner as in Comparative Example 13, except that the prepreg was created without being exposed to solvent vapor. [Comparative Example 16] A single-sided copper-clad board was obtained in the same manner as in Comparative Example 14, except that the prepreg was created without being exposed to solvent vapor. The performance of each example and each comparative example is shown in Table 1.
Shown in Tables 2 and 3.

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【table】 [Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus used in this manufacturing method, and FIG. 2 is a graph showing the state of temperature increase. DESCRIPTION OF SYMBOLS 1... Base material, 2... Resin holding base material, 3... Prepreg, 11... Resin liquid tank, 12... Squeeze roll, 13... Solvent vapor treatment chamber, 16... Dryer, 19... Partition wall .

Claims (1)

[Claims] 1. After obtaining a resin-retaining base material by allowing the base material to retain a resin liquid containing a thermosetting resin as a main component, in obtaining a prepreg by heating and drying this resin-retaining base material,
A prepreg manufacturing method characterized by obtaining a resin-retaining base material using a non-volatile content of 60% by weight or more as a resin liquid, exposing this resin-retaining base material to heated solvent vapor, and then heating and drying it. . 2. The method for producing a prepreg according to claim 1, wherein the thermosetting resin is an epoxy resin. 3. The prepreg manufacturing method according to claim 2, wherein the solvent vapor is water vapor, xylene vapor, a mixed vapor of xylene vapor and water vapor, methanol vapor, or a mixed vapor of methanol vapor and water vapor. 4. The method for producing a prepreg according to claim 1, wherein the thermosetting resin is an unsaturated polyester resin. 5. The prepreg manufacturing method according to claim 4, wherein the solvent vapor is water vapor, acetone vapor, or a mixed vapor of acetone vapor and water vapor. 6. The method for producing a prepreg according to claim 1, wherein the thermosetting resin is a diallyl phthalate resin. 7 Claim 6 in which the solvent vapor is water vapor
Prepreg manufacturing method described in section. 8. The method for producing a prepreg according to claim 1, wherein the thermosetting resin is a polyimide resin. 9. The prepreg manufacturing method according to claim 8, wherein the solvent vapor is water vapor and/or dimethylformamide vapor. 10 Claim 1 in which the base material is glass cloth
9. A method for producing a prepreg according to any one of Items 9 to 9. 11. The method for producing a prepreg according to any one of claims 1 to 9, wherein the base material is paper.