JP2924980B2 - Base paper for laminated board - Google Patents

Description

The present invention relates to a base paper for a laminate of the present invention, and more particularly to a base paper for a laminate having excellent dimensional stability.

[Prior art] Conventionally, laminated boards were made of glass cloth impregnated with synthetic resin such as epoxy resin and compression-cured, and cotton linter paper was impregnated with synthetic resin such as epoxy resin and phenol resin and compression-cured. And paper (usually bleached kraft paper) impregnated with a synthetic resin such as phenolic resin and compression-cured. Among them, those obtained by impregnating a paper with a phenolic resin and compression-hardening are relatively inexpensive and have good performance, and thus are widely used mainly in household electric appliances.

When this paper phenolic resin laminate is used as a printed wiring board, an electric circuit is formed by etching the copper foil attached to the surface thereof, and various electric components such as ICs, capacitors, The wiring board is completed by mounting resistors and soldering. 2. Description of the Related Art In recent years, electric products have become high-performance and small, and the mounting density of ICs, capacitors, resistors, and the like has increased, and the conductor pattern of wiring has been reduced in thickness.

For this reason, besides electrical properties such as insulation properties,
Demands for improved dimensional stability in the process of processing printed wiring boards have become increasingly severe. In order to improve the dimensional stability, the resin used, the molding conditions, and the like have been improved. However, it is considered that the improvement in the dimensional stability of the laminated base paper greatly contributes.

Various proposals have hitherto been made to improve the dimensional stability of the laminated base paper. For example, a method of adjusting the fiber orientation in a wire part of a paper machine to make the tensile strength of length / width appropriate (Japanese Patent Application Laid-Open No. 57-176788), or a method of producing fibers with a specific range of orientation angle (Japanese Patent Application 59−49959
Is known. The pulp usually used as a raw material for laminated base paper is bleached kraft pulp, but the grade also affects the dimensional stability, and so-called rigid pulp such as those with a thick cell membrane, those with a small fiber diameter, and those with a high elastic modulus are also used. Fiber is said to be good.

However, since pulp absorbs and desorbs due to environmental humidity, there is a limit in terms of dimensional stability. To compensate for this drawback, a method of blending glass fibers without moisture absorption and desorption (Japanese Patent Laid-Open No.
-16653, JP-A-59-201855, JP-A-60-1
No. 79244) has also been proposed. In addition, a method of adding a thermosetting resin such as a melamine resin, an epoxy resin, and a phenol resin to form a cross-linking or impregnation (Japanese Patent Laid-Open No.
No. 56-166055, JP-A-61-296037, JP-A-61
JP-296199, JP-A-63-211400) and the like have been proposed.

However, there is a problem that the mixing rate of the glass fiber cannot be increased so much because the mixing cost of the glass fiber is high, and the addition or impregnation of the resin deteriorates the recoverability of the damaged paper and lowers the efficiency.

[Problems to be solved by the invention]

Various proposals have been made to improve the dimensional stability of the laminated base paper, but there are still advantages and disadvantages in terms of quality, operability and cost, and a satisfactory method has not yet been found.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pulp obtained by compressing a laminated base paper that is inexpensive, efficiently and highly dimensionally stable by using a pulp that has been subjected to a compression treatment.

[Means for solving the problem]

The present invention relates to the following: 1. A pulp slurry is dehydrated through a wire to form a sheet, and then the sheet is compressed by a roll press to a moisture content of 65% or less, or a pulp further dried as necessary. Base paper for laminates, characterized in that pulp containing at least 50% of pulp is made into paper.

2. Laminated base paper characterized in that the density of the base paper sheet is 0.45 to 0.55 g / cm ³ and the pulp having an average lumen porosity of 3% or less contains at least 50%.

It is.

The present invention is characterized in that pulp which has been subjected to a compression treatment by a roll press after forming a wet sheet on a wire is used.

The roll press treatment may be performed separately from the formation of the wet sheet, but is preferably performed by a paper pulp machine.

The pulp subjected to the roll press treatment is preferably used in a wet pulp state. This is because the pulp that has once been subjected to the drying treatment has a poor binding property, and thus the strength and elastic properties of the paper tend to deteriorate.

In the present invention, the pulp used may be obtained from any tree species. Further, the present invention can be applied to both bleached pulp and unbleached pulp.

The mesh of the wire when forming a sheet from the pulp slurry used in the present invention is not particularly limited, but 20 to 70
Mesh is preferred. If the mesh size is less than 20 mesh, the amount of fibers in the wastewater to be dehydrated increases, contaminating the wastewater, and the pulp yield decreases. On the other hand, if the mesh size is 70 mesh or more, the wire is easily clogged, and the dewatering property is reduced. The type of the wire may be any of a cylinder type, a twin wire type, a long net type, and the like.

The basis weight of the sheet is not particularly limited, but is preferably in the range of 500 to 1500 g / m ² .

Roll press linear pressure is 70kg / cm ~ 250kg as normal pressure
/ cm, but is preferably 100 kg / cm or more, at which a higher result is obtained as the linear pressure is higher.

The number of processing steps in the roll press may be either one-step processing or multi-section processing of two or more steps.

The type of the roll may be any of a group roll (grooved roll), a suction roll, and a plain roll.

The mixing ratio of the pulp subjected to the roll press treatment is not limited, but it is preferable to mix the pulp by 50% or more.

When a laminated base paper is made from pulp treated according to the present invention, the morphology of the pulp fibers in the paper has remarkable characteristics. Laminated board paper has a density of 0.
Although it is generally adjusted to ^{45g / cm 3 ~0.55g / cm 3} ,
In the case of papermaking using ordinary pulp, in this density range, the ratio of the lumen (lumen) of pulp fibers in paper, that is, the lumen porosity becomes 3.0% or more, When the pulp treated according to the present invention is used, it has a feature that the lumen opening ratio is 3.0% or less.

The present inventors have studied the relationship between the lumen opening ratio and the dimensional stability of the laminated base paper and the laminated board. By reducing the lumen opening ratio of the pulp fiber in the base paper to 3.0% or less, the laminated base paper was examined. And that the dimensional stability of the laminate was significantly improved. This has a lumen opening rate of 3.0%
It is presumed to be a phenomenon caused by the following because the dimensional stability of the single fiber itself is improved and the fiber network structure formed in the papermaking stage is significantly different.

 The lumen opening ratio is measured as follows.

First, a photograph of the cross section of the laminated base paper sheet taken in a direction perpendicular to the flow direction of the paper machine is taken. The paper section is formed by embedding a resin and cutting with a sharp razor or microtome so as not to damage the form of the paper or fiber at the time of cutting. A cross-sectional photograph is taken using a scanning electron microscope because a magnification of about 1000 times is required in terms of measurement accuracy. Cross section area of single fiber (including lumen) from photographed paper cross section
The ratio of the lumen cross-sectional area to the ratio was expressed as a percentage, and this was defined as the lumen opening ratio. This lumen opening ratio varies depending on the fiber to be measured, so it should be at least 20%.
It is necessary to take the average of the lumen porosity of 00 or more fibers. In this way, the measured lumen porosity shows a very good correlation with the degree of pulp treatment and the dimensional stability of the laminate or laminate base paper.

Example-1 An unbeaten LBKP suspension having a concentration of 1.5% was dehydrated with a wire cylinder (vacuum type wire mesh 25 mesh) and a sheet of LBKP having a water content of 72% (1300 g / abs in absolute dry weight in terms of solid content) m ²⁾ was obtained. This sheet is processed in three stages by a roll press (grooved roll) (both rolls are grooved rolls, linear pressure 80 kg / cm for the first stage, 160 kg / cm for the second stage, 130 kg for the third stage)
/ cm) to produce a sheet of LBKP with a water content of 50%.

70% of LBKP treated in this way and 100%
From the above, a laminate base paper was formed by a conventional method.

The base paper containing 70% LBKP thus treated contains 70% pulp having a lumen opening ratio of 2.56%, and 100% pulp having a lumen opening ratio of 2.56% has a pulp content of 100%.

Comparative Example-1 A laminate base paper was produced by a conventional method using the ordinary LBKP of Example 1 which was not subjected to the roll press treatment. The lumen opening ratio of the pulp contained in this paper was 4.28.
Table 1 shows the measurement results of the elongation in liquid of the base paper and the heat shrinkage of the laminate for each base paper of Example-1 and Comparative Example-1.

(Note) Measurement method of heat shrinkage ratio Laminate base paper is impregnated with phenolic resin in two stages (first stage water-based resin Showa Polymer Showa BRL-2854 resin content 7%, second stage oil-based resin Showa Polymer) Manufactured by Shaunol BLS-3122 (resin content: 47%) and dried to produce impregnated paper called prepreg. Eight prepregs are stacked, heated and pressed by a hot press (temperature 165 ° C, pressure 100kg / c
(m ² , time 30 minutes) The laminate is manufactured by natural cooling at room temperature.

The laminated board (20cm x 20cm) molded in this way is subjected to heat treatment (after treatment at 80 ° C for 30 minutes and then at 120 ° C for 15 minutes), and the length in the vertical (T) direction and the horizontal (Y) direction before and after heating Is measured with a high-precision secondary coordinate measuring device (Digital Japan Screen Manufacturing Co., Ltd., digital reader DR-550), and is obtained by the following equation.

Measurement method of elongation in liquid J.TAPPI No.27 Paper and paperboard are measured by the immersion elongation test B method. (Methyl alcohol was used in place of water) Example 2 A wet sheet was produced in the same manner as in Example 1 except that the roll press treatment was performed in one step at the linear pressure shown in Table 2 in Example 1. Four types of pulp were collected from the obtained four types of wet sheets, and hand-made paper having a rice scale of 130 g / m ² and a density of 0.5 g / cm ³ was prepared by a conventional method. (1st stage press line pressure 85kg / cm, 125kg / c
m, .165 kg / cm, 205 kg / cm) Comparative Example 2 Hand paper similar to that of Example 2 was prepared using LBKP without a roll press treatment. The elongation in liquid was measured for the handmade paper samples of Example-2 and Comparative Example-2. (Table 2) As shown by the measurement results, it can be seen that, as compared with Comparative Example-2, Example-2 was good, the press linear pressure was high, and the lumen opening ratio was small.

[Effect of the Invention] A laminate having high dimensional stability according to the present invention can be provided at low cost.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 1/03 610 H05K 1/03 610T (72) Inventor Isao Odaka 1-10-6 Shinonome, Koto-ku, Tokyo Oji Paper Co., Ltd. Central Research Laboratory (72) Inventor Taketo Okutani 1-10-6 Shinonome, Koto-ku, Tokyo Oji Paper Co., Ltd. Product Research Laboratory (56) References JP-A-64-14398 (JP, A) JP-A-2-175996 (JP, A) JP-A-1-246499 (JP, A) JP-A-46-3936 (JP, A) JP-A-56-128388 (JP, A)

Claims (2)

(57) [Claims] 1. A wet pulp obtained by dehydrating a pulp slurry through a wire to form a sheet, and then compressing the sheet by a roll press to a water content of 65% or less.
Alternatively, a base paper for a laminated board characterized in that papermaking is performed using a pulp containing 50% or more of pulp further dried as necessary as a raw material. 2. Pulp having a base paper sheet density of 0.45 to 0.55 g / cm ³ and an average lumen porosity of 3% or less.
% Or more.