JP2525704B2 - Manufacturing method of laminated base paper - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base paper for a laminated board using a pulp excellent in suitability for the laminated board.

[0002]

2. Description of the Related Art A base paper for a laminated board is processed with a phenol resin, a polyester resin or the like and is mainly used as a printed wiring board in a wide variety of fields such as consumer electronic devices and industrial electronic devices. In recent years, as the performance of electronic parts has become more sophisticated, the conditions under which printed wiring boards are used have become more severe, and the physical properties required for the base paper for electrical insulating laminates have become even more severe. In particular, in order to cope with higher density of wiring on the substrate, there has been an increasing demand for a base paper for laminated board which has good punching workability, dimensional stability, heat resistance and electrical characteristics. Conventionally, a bleached kraft pulp made of wood or a pulp having a high α-cellulose content has been used as a base paper for laminated boards (Japanese Patent Application Laid-Open No. 64-64-
14398) or cotton linters pulp has been used in many cases.

However, a laminated board using bleached kraft pulp has a problem that when punching is performed at a low temperature, delamination occurs around the punching holes and cracks occur between the holes. On the other hand, the base paper for laminated boards using cotton linter has relatively good punching workability at low temperature, heat resistance, and electrical characteristics compared to the base paper for laminated boards using bleached kraft pulp, but the dimensions during heating It has the drawback of being extremely inferior in stability.
It is also known that pulp having a high α-cellulose content causes problems such as bending of fibers and deterioration of dimensional stability of a laminated plate (Japanese Patent Laid-Open No. 2-175996).

[0004]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a base paper for a laminated board which is excellent not only in dimensional stability but also in punching workability, heat resistance and electric characteristics.

[0005]

The inventors of the present invention have found that the dimensional stability of a laminated sheet depends on the flexibility of the pulp fiber, and other performances such as punching workability, heat resistance, and electrical characteristics depend on the hemicellulose content. As a result of intensive research focusing on the close relationship, hemicellulose is 20% or less and the fiber bending degree is 15 or less by bleaching unbleached kraft pulp with a Kappa number of 12-25 including a specific enzyme treatment. It was found that the objective can be achieved by using the pulp prepared as described above, and the present invention has been completed based on this finding.

Unbleached kraft pulp having a Kappa number of 12-25 is used in the present invention. If the Kappa number is 12 or less, a pulp having a fiber bending degree of 15 or less cannot be obtained, and if the Kappa number is 25 or more, it becomes difficult to reduce the hemicellulose content to 20% or less, and processability becomes
Heat resistance and electrical characteristics deteriorate. The content of hemicellulose of the present invention is measured according to TAPPI T-249hm-85, by hydrolyzing the pulp, and separating and quantifying pentose and hexose which are hydrolysates of the hemicellulose component using a high performance liquid chromatograph. Done. If the hemicellulose content exceeds 20%, heat resistance and electrical characteristics deteriorate, which is not preferable. If the fiber flexibility is 15 or more, the dimensional stability is deteriorated.

[0007] Enzymes used in this invention, hemicellulase, cellulase, esterase, a pectinase or a mixture of this and the like, for example, Trichoderma bi Ride,
Enzymes produced by Trichoderma reesei, Aspergillus niger, etc. are used. For example, xylanase is effective in hardwood because xylose is the main component of hemicellulose. Amount of enzyme added at that time, reaction temperature,
Reaction conditions such as reaction pH differ depending on the enzyme used,
It is desirable to use the conditions under which the enzyme used works most efficiently. For example, D. Miller: J.M. Wood C
hem. Tech. Vol 11 No. 1 (1991)
Conditions such as those shown in 23 can be used. The oxygen treatment of the present invention is preferably performed until the residual hemicellulose content becomes 20% or less.

Oxygen treatment can be incorporated anywhere in the bleaching process, such as unbleached, in the middle of bleaching, at the end of bleaching. The bleaching process applicable at this time is chlorine.
A multi-stage bleaching in the sequence of (C) -alkali (E) -sodium hypochlorite (H) -alkali (E) -chlorine dioxide (D) can be used, but is not limited thereto. As the treatment conditions of each bleaching stage, the chlorine addition amount and the alkali addition amount are the amounts corresponding to the amount of lignin (kappa number) remaining in the unbleached pulp, and sodium hypochlorite, alkali,
It is desirable to add chlorine dioxide in an amount such that the whiteness is about 86 to 92%. For example, in the case of pulp with an unbleached Kappa number of 16, the chlorine stage has a pulp concentration of 3% and a chlorine addition rate of 3.0%.
(Vs pulp), treatment temperature 50 ° C; pulp concentration 10%, alkali addition ratio 2.0% (vs pulp), treatment temperature 60 ° C; sodium hypochlorite stage pulp concentration 10
%, Sodium hypochlorite addition rate 1.1% (vs. pulp),
Treatment temperature 45 ℃; pulp concentration 10%, alkali addition rate 0.5% (vs pulp) in alkaline stage, treatment temperature 60 ℃; pulp concentration 10%, chlorine dioxide addition rate 0.8% in chlorine dioxide stage
Conditions (such as pulp) and processing temperature of 75 ° C can be used. Further, oxygen, hydrogen peroxide, etc. can be used as appropriate.

[0009]

EXAMPLES The effects of the present invention are shown below by examples. Example 1 Unbleached hardwood kraft pulp with a Kappa number of 16 was added at a concentration of 10
% And acetic acid buffer and trade name Cartazyme HS
A diluent (manufactured by Sand Chemical Co., Ltd.) was added to obtain a mixture having 1 U / ml xylanase activity. After reaction at 50 ° C. for 3 hours, bleaching was performed under the conditions shown in Table 1. By this bleaching, bleached pulp having a whiteness of 88% was obtained. This pulp was handmade to prepare a base paper for a laminate having a basis weight of 135 g / m ² and a density of 0.5 g / cm ³ . This base paper is impregnated with a commercially available phenol resin (BLS-3122 manufactured by Showa Highpolymer Co., Ltd.) and dried to make a prepreg with a resin adhesion amount * of 52%. 8 prepregs are stacked and bonded. One piece of the copper foil with the agent (thickness 35 μm) was laminated and heat-pressed at 155 ° C. and 100 kg / cm ² for 60 minutes to obtain a 1.6 mm-thick single-sided copper-clad laminate.

Example 2 An unbleached hardwood kraft pulp having a kappa number of 16 was bleached under the conditions shown in Table 1 to prepare a water slurry having a concentration of 3%.
A xylanase enzyme derived from Trichoderma viride (manufactured by Shin Nippon Chemical Industry Co., Ltd., trade name Sumizyme TXS) and a phosphate buffer were added to obtain a mixture having 0.6 U / ml xylanase activity. Enzymatic hydrolysis at 45 ℃ for 6 hours, whiteness 89%
Of pulp was obtained. This pulp is handmade and the basis weight is 135 g /
A base paper for a laminated plate having m ² and a density of 0.5 g / cm ³ was prepared. Using this base paper, a single-sided copper-clad laminate was obtained in the same manner as in Example 1.

Comparative Example 1 Unbleached hardwood kraft pulp with a Kappa number of 16 was added at a concentration of 10
Prepare a mixture by adding acetate buffer so that
After reacting at 50 ° C. for 3 hours, bleaching was performed under the same conditions as in Example 2 in Table 1. By this bleaching, bleached pulp having a whiteness of 88% was obtained. Using this pulp, a single-sided copper-clad laminate was obtained in the same manner as in Example 1.

Comparative Example 2 Unbleached kraft pulp with a kappa number of 16 was bleached under the same conditions as in Example 2 in Table 1, slurried to a 3% concentration in water and adjusted to pH 6.8 with a phosphate buffer. After that, it was treated at 45 ° C. for 6 hours to obtain a pulp having a whiteness of 86%. This pulp was handmade to prepare a base paper for a laminate having a basis weight of 135 g / m ² and a density of 0.5 g / cm ³ . Using this pulp, a single-sided copper-clad laminate was obtained in the same manner as in Example 1. Table 2 shows the performance of the laminated plates obtained in the above Examples and Comparative Examples.

[0013]

[Table 1]

[0014]

[Table 2]

* 1 Hemicellulose content: TAPPI
It was hydrolyzed according to T-249hm-85, separated by high performance liquid chromatography, and calculated from the sugar composition identified by the fluorescence generated when it was reacted with arginine. * 2 Fiber flexibility: For all fibers projected by enlarging and projecting randomly sampled fibers (total fiber count is 500
Numerical value representing all the measured values was obtained. The fiber bending degree was calculated by the following formula. Lt: Actual fiber length Ls: Linear distance connecting both ends of fiber long axis * 3 Low temperature punching workability: Die hole wall spacing is 0.8, 1.0,
Equipped with a pair of 1.2 and 1.6 mm round holes and a pair of 1 mm x 2 mm square holes,
The surface temperature of the laminated plate is room temperature, 35 ℃, 55 ℃ using a test die with a clearance of 0.05 mm on one side between the punch and the die.
After punching, the surface, holes, and cuts after punching are judged according to ASTM D617. Excellent, good, good, bad
Graded. * 4 Insulation resistance: Measured according to JIS C6481 and JIS K6911. * 5 Warpage and solder heat resistance: Measured according to JIS C6481.

[0016]

As shown in Table 2, the laminated sheet using the laminated base paper of the present invention has improved low temperature punching workability, electrical characteristics and heat resistance while maintaining the dimensional stability, and its industrial significance. Is extremely large.

Claims (2)

(57) [Claims] 1. Use of a pulp having a hemicellulose content of 20% or less and a fiber flexibility of 15 or less by performing bleaching including enzyme treatment in the bleaching process of unbleached kraft pulp having a Kappa number of 12 to 25. A method for producing a base paper for laminated boards, characterized by: 2. The method according to claim 1, wherein the enzyme used is hemicellulase, cellulase, esterase, pectinase, or a mixture thereof.