JP2733177B2 - Manufacturing method of laminated board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminate having excellent dimensional stability and small warpage.

[0002]

2. Description of the Related Art In recent years, in a consumer electronic device, the thickness of a paper-based phenolic resin laminate has been reduced. However, as the laminate becomes thinner, warpage occurs due to variations in dimensional changes in the laminate. It has become. This is because paper-based phenolic resin laminates have excellent water resistance as a property of phenolic resin, but because of the inherent water absorption of paper, dimensional changes occur due to moisture absorption, and these dimensional changes vary within the laminate. Causes wavy warping. Therefore, various improvements have been attempted for the purpose of improving the performance of this kind. For example, a method in which a paper base material is previously treated with a low-condensation phenol resin or a melamine resin to improve moisture resistance, and a normal phenolic resin is added thereto by using a paper-containing paper mixed with a resin during paper-making. Although a method for improving moisture resistance by impregnation has been proposed, dimensional stability and warpage have not yet been sufficient.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper-based phenolic laminate which has good dimensional stability and is less likely to be warped even when thinned.

[0004]

According to the present invention, a melamine resin-made base paper is used as a base paper for a laminate, a mixture of a phenol resin having a low degree of condensation and a melamine resin is impregnated, dried by heating, and then dried. And producing a prepreg which is dried by heating, stacking a plurality of the prepregs, and forming the prepreg by heating and pressurizing, and a method for producing a laminate having excellent dimensional stability and warpage. The base paper for a laminate used in the present invention is a melamine resin-made paper in which a melamine resin is formed at the time of paper-making such as kraft paper and cotton linter paper. Preferably, a mixture of the paper base material and the melamine resin in a ratio of 3 to 10 parts by weight with respect to 10 parts by weight of the phenol resin having a low degree of condensation is added so that the resin adhesion amount is 5 to 25% by weight. The paper-based phenolic resin laminate is manufactured by impregnating and drying, and then impregnating again with a phenolic resin such as a dry oil-modified phenolic resin and laminating and molding.

[0005] Since the production method of the present invention has the above characteristics, a paper-based phenol laminate having excellent dimensional stability and small warpage can be obtained. That is, in the conventional production method, the impregnating property of the undercoat phenolic resin on the paper base material was insufficient, so that the adhesiveness between the paper fibers of the laminated board was weak, which caused a decrease in dimensional stability. Therefore, by using an undercoating resin composed of a low-condensation phenol resin and a melamine resin having good compatibility and a high impregnation effect on a base paper made of melamine resin having a large adhesive force between paper fibers, the adhesion between paper fibers is improved. The force can be increased, the dimensional stability of the laminate can be improved, and a paper-based phenol laminate having less warpage can be obtained.

In the present invention, the melamine resin to be laid on the base paper is a water-soluble melamine resin (for example, monomethylol melamine or nisimimethylol melamine), and is added in an amount of 0.1 to 5 parts by weight based on pulp. You. The phenolic resin used for the undercoat varnish is a water-soluble phenolic resin having a low degree of condensation, which can be obtained by reacting phenols such as phenol, cresol, and nonylphenol with an aqueous formaldehyde solution or paraformaldehyde using a tertiary amine catalyst or the like. The melamine resin is mainly composed of a methylolated melamine resin, and is obtained by reacting melamine with an aqueous formaldehyde solution or paraformaldehyde with a tertiary amine catalyst or the like.

[0007]

EXAMPLES Examples of the present invention will be described together with comparative examples. Example 1 A 10-mils cotton linter paper incorporating 0.5% melamine resin (formaldehyde / melamine reaction molar ratio 2.5, molecular weight 300) was mixed with a phenol resin having a low degree of condensation (formaldehyde / phenol reaction mole). Ratio 2.0, molecular weight 200) 10 parts and melamine resin (formaldehyde / melamine reaction molar ratio 3.0, molecular weight 300) 5
Varnish (resin content 25%) mixed in the ratio of parts is applied and impregnated so that the resin adhesion amount becomes 12 to 15%, and then heated and dried.
Further, a tung oil-modified resol type phenol resin was applied and impregnated, and dried by heating to prepare a prepreg having a resin content of 45 to 50%. Four prepregs at 160 ° C., 100 kg / cm
^2. Forming was performed in 100 minutes to obtain a laminate having a thickness of 0.8 mm.

Comparative Example 1 A cotton linter paper containing no melamine resin was primed with only the low-condensation phenol resin used in Example 1. Thereafter, in the same manner as in Example 1, the tung oil-modified phenol resin was applied and impregnated, followed by lamination molding to obtain a laminate. << Comparative Example 2 >> Only the phenolic resin used in Example 1 was undercoated on the melamine resin paper used in Example 1. Hereinafter, a laminated board was obtained in the same manner as in Example 1. Comparative Example 3 An undercoat varnish composed of a phenol resin and a melamine resin not incorporating the melamine resin of Comparative Example 1 was also impregnated. Hereinafter, a laminated board was obtained in the same manner as in Example 1.

Table 1 shows the results of the characteristic tests of the laminate.

[Table 1]

[0010]

As is clear from the above results, according to the method for manufacturing a laminated board of the present invention, the dimensional stability due to moisture absorption caused by the inherent water absorption of the paper base which is a defect of the conventional laminated board. It was possible to significantly improve the poor quality and to minimize the wavy warpage.

Claims (1)

(57) [Claims] 1. A melamine resin-made base paper is used as a base paper for a laminate, impregnated with a mixture of a phenol resin and a melamine resin having a low degree of condensation and dried by heating, and then impregnated with a phenol resin and dried by heating. A method for producing a laminate having excellent dimensional stability and warpage, comprising preparing a prepreg, stacking a plurality of the prepregs, and subjecting the prepregs to heat and pressure molding.