JPH07329090A - Manufacture of laminated sheet - Google Patents

Abstract

PURPOSE:To manufacture a laminated sheet without using a solvent, by a method wherein a fixed number of sheets on which dihydro-1, 3-benzoxazines having a specific group in a molecule are watermarked are piled upon each other, heated and pressurized. CONSTITUTION:Dihydro-1, 3-benzoxazines (hereinafter referred to as dihydrobenzoxazine resin) having at least two groups, which is shown by the formula, in a molecule is pulverized, dispersed into water together with a fiber, which is watermarked by wire cloth and made into a sheetlike state. A cellulose fiber is preferable as the fiber. A constituent body which is obtained by piling up a fixed number of the sheets to each other are coated with a release film, heated. pressurized and a laminated sheet is obtained. Hereupon, R<1> represents a phenyl group, a substituted phenyl group, a methyl group or a cyclohexyl group and R<3> represents hydrogen, a methyl group, an ethyl group or a phenyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electric insulating plate, particularly a laminated plate used as an insulating substrate for a printed wiring board.

[0002]

2. Description of the Related Art A laminated board (hereinafter simply referred to as a laminated board) used as an electrical insulating board, particularly as an insulating substrate for a printed wiring board, has a sheet-like fiber base material coated and impregnated with an insulating material resin and heated to produce a prepreg. Is obtained by stacking a predetermined number of these prepregs and heating and pressing. As the insulating material resin, thermosetting resins such as phenol resin, epoxy resin and unsaturated polyester resin are mainly used. A large amount of solvent is used in the step of coating and impregnating the sheet-shaped fiber base material with the insulating material resin.

[0003]

However, since a large amount of solvent is used in the step of coating and impregnating the insulating fiber resin on the sheet-shaped fiber base material, it prevents the occurrence of disasters such as fire and explosion and vaporizes the solvent vapor. A large amount of cost is required for the installation and maintenance of equipment in consideration of the prevention of environmental pollution due to the production cost.

It is known that dihydro-1.3-benzoxazines are polymerized and cured by heating without producing a volatile by-product component (see JP-A-49-47378). ), A method of using a solvent such as methyl ethyl ketone is used for manufacturing the laminated plate. For this reason, due to the peculiarities of the materials, a laminated plate using a cured product of dihydro-1.3-benzoxazines as a matrix has not been put to practical use. The present invention provides that when dihydro-1.3-benzoxazines cure
It is an object of the present invention to provide a method for producing a laminated plate without using a solvent, taking advantage of the fact that the volatile by-product components are polymerized and cured.

[0005]

The present invention provides a compound having
Dihydro-1.3-benzoxazines having two or more groups shown in (hereinafter referred to as dihydrobenzoxazine resin)
Is a method for producing a laminated plate, characterized in that a predetermined number of sheets obtained by making the above are stacked and heated and pressed.

[0006]

[Chemical 2] In the chemical formula 2, R ¹ is a phenyl group, a substituted phenyl group, a methyl group or a cyclohexyl group, and R ² is hydrogen, a methyl group, an ethyl group or a phenyl group.

The dihydrobenzoxazine resin comprises a compound having two or more hydroxyphenylene groups in which at least one of the ortho positions of the hydroxyl group is hydrogen in one molecule, a primary amine and formaldehyde, and an ortho group of the hydroxyphenylene group. To 1 mol of a hydroxyl group in which at least one of the positions is hydrogen, a primary amine of 0.2 to
0.9 mol and formaldehyde of primary amine 2
It is produced by reacting in a molar ratio of at least twice.

Specifically, a compound having two or more hydroxyphenylene groups in which at least one ortho-position of a hydroxyl group is hydrogen in one molecule (hereinafter referred to as a compound having a reactive hydroxyphenylene group) and 1
The mixture with a primary amine is added to an aldehyde heated to 70 ° C. or higher to 70 to 110 ° C., preferably 90 to 110 ° C.
React at 100 ° C for 20 minutes to 2 hours, then 120 ° C
The dihydrobenzoxazine resin is obtained by drying under reduced pressure at the following temperature.

The primary amine is reacted in an amount of 0.2 to 0.9 mol, and formaldehyde is reacted in a ratio of at least twice the molar amount of the primary amine with respect to 1 mol of the hydroxyl group of the compound having a reactive hydroxyphenylene group. It is essential to let them do it. If the amount of the primary amine is less than 0.2 mol, the number of dihydrooxazine rings will be small, so that when the obtained compound is cured, only a cured product having a low crosslink density and a low strength can be obtained. If it is more than 0.9 mol, the degree of extension of the molecular chain will be small and the crosslink density will be small, so the temperature will be 200 ° C.
If it exceeds, softening or heat deterioration is not preferable.

The blending amount of the primary amine with respect to the compound having a reactive hydroxyphenylene group can be determined as follows. That is, 1 mol of the same molar amount as all hydroxyl groups of the compound having a hydroxyphenylene group
The amount of the reacted hydroxyl group, that is, the amount of the reactive hydroxyl group in the compound having the hydroxyphenylene group is estimated from the weight of the product actually obtained by reacting the primary amine, and calculated as the above molar ratio. To do.

As the compound having two or more reactive hydroxyphenylene groups in one molecule, various compounds partially having a phenol nucleus can be used. Specifically, phenol novolac resin, resol resin, phenol-modified xylene resin, alkylphenol resin,
Examples include melamine phenol resin and phenol-modified polybutadiene. These are not particularly limited, but those in which the ortho position of the hydroxyl group serving as a cross-linking point is unsubstituted are desirable in terms of the properties of the cured product. Therefore, for example, in the case of phenol novolac resin, the ortho ratio is small and the molecular weight is relatively small. It is preferred to use small so-called random novolacs. The above resin is a set of compounds having different numbers of hydroxyphenylene groups capable of reacting in one molecule, and some of the thermosetting compounds produced during the production are polymerized with each other.

Specific examples of the primary amine include methylamine, cyclohexylamine, aniline and substituted aniline. If it is an aliphatic amine, the obtained thermosetting compound cures quickly, but the heat resistance of the cured product is slightly inferior,
When the aromatic amine such as aniline is used, the cured product obtained by curing the obtained thermosetting compound has good heat resistance but slows curing.

The dihydrobenzoxazine resin thus obtained is preheated to 80 to 180 ° C., preferably 12
By heat-treating at 0 to 160 ° C., a part of it is prepolymerized to adjust the curing speed and melt viscosity during molding.

After synthesizing the dihydrobenzoxazine resin, it is crushed, dispersed in water together with the fiber, made up with a net, and dried to form a sheet. Cellulose fibers are suitable as the fibers, but inorganic short fibers such as glass are also used. The fibers may be mixed with a powder of dihydrobenzoxazine resin to form a dry sheet.

The particle size of the dihydrobenzoxazine resin powder is 300 μm or less, preferably 50 μm or less.
The amount of dihydrobenzoxazine resin powder in the sheet is 30 to 75% by weight. If it is less than 30% by weight, molding cannot be carried out, and if it is more than 75% by weight, the strength required as a laminate cannot be obtained.

A laminate obtained by covering a predetermined number of sheets containing dihydro-1.3-benzoxazines having two or more groups represented by Chemical Formula 1 in the molecule with a release film, heating and pressurizing the laminate, To get If a metal foil, for example, a copper foil is stacked instead of the release film, a metal foil-clad laminate can be obtained. Copper foil is usually used as the metal foil, but metal foil such as nickel foil and aluminum foil may be used depending on the required characteristics.

[0017]

【Example】

Example 1 1.9 kg phenol, formalin (37% water soluble)
1.0 kg and 4 g of oxalic acid were placed in a 5 liter reaction kettle and reacted at reflux temperature for 6 hours. Subsequently, the inside pressure was reduced to remove unreacted phenol and water. The obtained resin has a softening point of 84 ° C. (ring and ball method) 3 to a polynuclear body ratio of 82/18.
(Peak area ratio by gel-vermi- chromatography).

1.70 kg (corresponding to 16 mol of hydroxyl group) of phenol novolac resin synthesized above and 0.93 kg (corresponding to 10 mol) of aniline were mixed and stirred at 80 ° C. for 5 hours to prepare a uniform mixed solution. 1.62 kg of formalin was charged into a 5 liter reaction kettle and heated to 90 ° C., and the mixed solution of the phenol novolac resin and aniline was added thereto, and the mixture was kept at reflux temperature for 30 minutes, then at 2 ° C. at 100 ° C. The condensed water was removed by depressurizing for a time. A resin composition was obtained in which 71% of the reactive hydroxyl groups were dihydro-1.3-benzoxazinized.

The method for calculating the amount of hydroxyl groups that can react is as follows. 1.70 kg of the phenol novolac resin
(Corresponding to 16 mol of hydroxyl group) 1.49 kg (1
6 mol) and 2.59 kg of formalin are reacted in the same manner to remove all the reactive hydroxyl groups from dihydro-1.3.
-Becomes benzoxazine. The unreacted aniline and formalin and the water remaining in the reaction system, ie, the yield of the dihydrobenzoxazine resin, was 3.34 kg. This corresponds to dihydro-1.3-benzoxazinized by reacting 14 mol of the hydroxyl groups of the phenol novolac resin. From this, the resin composition obtained in this example has a reactive hydroxyl group of 14 mol.
It can be seen that, of these, 10 mol (71%) was dihydro-1.3-benzoxazinated.

Example 2 1,2-Butadiene (Nippon Soda Co., Ltd., B-100
0) 0.92 kg, phenol 3.30 kg, and p-toluenesulfonic acid 1 g were charged in a 5 liter reaction kettle, and 8
The reaction was carried out at 0 ° C for 5 hours. After cooling and washing with water, unreacted phenol was removed by steam distillation to obtain 1.41 kg of polybutadiene-modified phenol resin. From the weight of the added phenol, the hydroxyl group equivalent is 270.

2.70 kg (corresponding to 10 mol of hydroxyl groups) of the obtained polybutadiene-modified phenol resin, 0.56 kg (corresponding to 6 mol) of aniline and 0.97 of formalin.
Using kg, a resin composition in which 73% of the hydroxyl groups capable of reacting were dihydro-1.3-benzoxazinized was obtained in the same manner as in Example 1.

Example 3 Tung oil 0.50 kg, m-cresol 4.00 kg, p-
4 g of toluenesulfonic acid was charged into a 5 liter reaction kettle and reacted at 80 ° C. for 5 hours. After cooling and washing with water, unreacted m-cresol was removed by steam distillation to obtain tung oil / m-
0.82 kg of a cresol reaction product was obtained. The hydroxyl equivalent is 280 from the weight of the added m-cresol.

Tung oil / m-cresol reaction product obtained 2.
80 kg (corresponding to 10 mol of hydroxyl groups) of 0.56 aniline
A resin in which 66% of the hydroxyl groups capable of reacting with dihydro-1.3-benzoxazine was obtained by the same operation as in Example 1 was obtained using kg (corresponding to 6 mol) and 0.97 kg of formalin.

Example 4 Xylene resin (using Mitsubishi Gas Chemical Co., Ltd. trade name Nikanol H, average molecular weight 557, reactive group equivalent 96)
Charge 0.96 kg, phenol 4.00 kg, and p-toluenesulfonic acid 4 g into a 5 liter reaction kettle and keep at 80 ° C.
And reacted for 5 hours. After cooling and washing with water, unreacted phenol was removed by steam distillation to obtain 1.12 kg of a phenol-modified xylene resin. 0.31 kg of phenol substituted with oxymethylene group from unreacted phenol remaining amount
Met. The hydroxyl equivalent of the xylene resin synthesized from this is 340.

The xylene-modified phenolic resin obtained 3.
40 kg (corresponding to 10 mol of hydroxyl groups), aniline 0.28
By using the same amount of kg (corresponding to 3 mol) and 0.49 kg of formalin, the same procedure as in Example 1 was carried out to obtain a resin composition in which 79% of hydroxyl groups were dihydro-1.3-benzoxazinized.

Production of Laminated Plates 1 to 4 The obtained four kinds of dihydrobenzoxazine resins were added to 1
It was crushed to a size of not more than 00 μm, dispersed in water at a ratio of 30% by weight with respect to pulp, and paper was made. In addition, the laminated board 1 is the same as that of the first embodiment.
Resin, the laminated plate 2 uses the resin of Example 2, the laminated plate 3 uses the resin of Example 3, and the laminated plate 4 uses the resin of Example 4. 7 sheets thus obtained and 1 sheet of copper foil having a thickness of 18 μm were superposed, set between end plates, and heated at a temperature of 17 with a multi-stage press.
It was heated and pressurized at 0 ° C. and a pressure of 11 MPa for 60 minutes.

Production of Laminate 5 The dihydrobenzoxazine resin obtained in Example 1 was
It was pulverized to 100 μm or less, and was dispersed in water at a ratio of 30% by weight with respect to the pulp which was previously treated with the water-soluble melamine-modified phenol resin, and paper was made. Seven sheets thus obtained and one sheet of copper foil having a thickness of 18 μm were overlapped with each other, set between end plates, and heated and pressed at a temperature of 170 ° C. and a pressure of 11 MPa for 60 minutes by a multistage press.

Comparative Example Tung oil and phenol were reacted under acidic catalyst, and then 85
% Paraformaldehyde was added and the reaction was carried out in the presence of an alkali catalyst to form a resol, to obtain a tung oil-modified phenol resin having a tung oil modification rate of 39%. This tung oil modified phenolic resin 100
25 parts by weight of tetrabromobisphenol A diglycidyl ether was added to parts by weight and dissolved in methyl ethyl ketone to prepare a varnish for impregnation. A water-soluble melamine-modified phenolic resin is applied to a kraft paper having a thickness of 0.2 mm so as to have a resin content of 15% by weight and dried, and then the impregnating varnish is applied so that the resin adhesion amount becomes 53% by weight. Was impregnated and dried to obtain a prepreg. Seven pieces of the obtained prepreg were combined and combined with one piece of copper foil with an adhesive, and heated and pressed at a temperature of 170 ° C. and a pressure of 8 MPa for 90 minutes to obtain a laminated plate.

The laminated plate thus obtained was examined for heat resistance in air, loss on heating, water absorption and insulation resistance. The results are shown in Table 1. The heat resistance in the air is the time until it is kept in a dryer at 200 ° C. and causes blistering. The weight loss on heating is the change in weight before and after holding in a dryer at 200 ° C. for 10 minutes. Water absorption is 23 after treatment at 50 ° C for 24 hours.
It is the percentage of the weight change before and after holding in water at 0 ° C. for 24 hours. The insulation resistance was measured by removing the copper foil by etching and holding it in boiling water for 2 hours.
It is a reading of the insulation resistance meter when a taper pin of the insulation resistance meter is inserted into two holes with a diameter of 5 mm provided in mm and a direct current of 500 V is applied for 1 minute.

[0030]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Test item Laminated board 1 Laminated board 2 Laminated board 3 Laminated board 4 ─ ────────────────────────────── Air heat resistance (min) 60 45 40 40 Heat loss (%) 0.16 0 .20 0.21 0.22 Water absorption rate (%) 0.65 0.60 0.61 0.61 Insulation resistance (Ω) × 10 ⁸ 5 4 5 5 5 ━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━ Laminate 5 Comparative example ───────────────────── Air heat resistance (minutes ) 42 30 Heat loss (%) 0.20 0.35 Water absorption (%) 0.35 0.75 Insulation resistance (Ω) × 10 ⁸ 5 2 ━━━━━━━━━━━━━━━━ ━━━━━━

[0031]

EFFECTS OF THE INVENTION According to the method of the present invention, since the benzoxazine resin can be molded without using a solvent by utilizing the characteristic that a low molecular weight reaction by-product is not generated when it is cured, it is excellent in safety and environmental hygiene. ing.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B29K 105: 22 (72) Inventor Yasuyuki Hirai 1500 Ogawa, Shimodate-shi, Ibaraki Hitachi Chemical Co., Ltd. Shimodate in the factory

Claims (3)

[Claims] 1. A process for producing a laminated sheet, comprising stacking a predetermined number of sheets containing dihydro-1.3-benzoxazines having two or more groups represented by Chemical formula 1 in the molecule and heating and pressing the sheets. Method. [Chemical 1] In the formula, R ¹ is a phenyl group, a substituted phenyl group, a methyl group or a cyclohexyl group, and R ³ is hydrogen, a methyl group,
It is an ethyl group or a phenyl group. 2. A method for producing a laminate, wherein the dihydro-1.3-benzoxazine is dihydro-1.3-benzoxazine obtained by reacting a phenol resin with formalin and a primary amine. 3. A predetermined number of sheets are superposed, a metal foil is superposed on the outer side of the superposed sheets, and the sheets are heated and pressed.
Or the manufacturing method of the laminated board as described in 2.