JPH01259937A - Base of good dimension stability for laminate and laminate using it - Google Patents

Abstract

PURPOSE:To enhance punching properties, heat resistance and dimension stability by impregnation a base for laminating using linters of specific flex degree of sulfate pulp, or else sulfite pulp with resin for laminating, and heat- laminating. CONSTITUTION:A base for laminating with its fiber flex degree reduced down to 50 or less is prepared by correcting the fiber shape by means of heating treatment for high fiber flex degree of linters, unbeaten sulfate pulp, or else unbeaten sulfite pulp. Thermoplastic resin such as phenol resin, melamine resin or the like is used for the resin for laminating, and prepregs are prepared by impregnating the base for laminating with said resin, and then the same are laminate molded under heat to manufacture a laminate. The range of 40-65wt.% of the volume of impregnated resin to the base is suitable. Thus, the dimension stability can be enhanced by said constitution without lowering purchasing properties and heat resistance of the laminate.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a base paper for laminates used for manufacturing laminates having excellent punching workability, heat resistance, and dimensional stability, and the base paper. This relates to the laminate used.

(Prior Art) Base paper for laminates is impregnated with synthetic resin such as phenol resin, and then formed into laminates, which are used in a wide range of industrial and consumer electronic devices.

Sulfate pulp is often used as base paper for laminates, which is currently widely used as a raw material and is made from wood pulp.

In addition, Kotton linter paper is a base paper for laminated boards made of materials other than wood pulp, although the amount used is small.

(Problems to be Solved by the Invention) With the remarkable development of the electronics industry in recent years, the usage conditions for printed wiring boards have become harsher, and there is a growing tendency for the physical properties required of laminate substrates to become more sophisticated.

In particular, laminates with excellent dimensional accuracy are required to accommodate high-density wiring.

In addition to the requirement for dimensional accuracy, punching workability is also required.

A base material that also has heat resistance and the like is desired.

Sulfate valve paper, which is currently widely used as a base paper for laminated boards, has relatively good dimensional stability, but its punching workability and heat resistance are inferior to linter paper.

On the other hand, linter paper has relatively good punching workability.

Although it has heat resistance, its dimensional stability is inferior to sulfate valve paper.

Furthermore, when using a base paper for laminates made of wood pulp with an α-cellulose content of 87.0% or more as shown in JP-A-60-79952, it has punching workability comparable to that of linter paper and good heat resistance. However, like linter paper, it does not have sufficiently satisfactory properties in terms of dimensional stability.

Among these, one of the major factors contributing to poor dimensional stability of laminates made of laminate base paper using linter paper and wood bulbs with a high α-cellulose content is the influence of fiber morphology.

(Means for solving the problem) Regarding the dimensional stability of the laminate, for example, linter paper or α-
The reason for poor dimensional stability when using pulp paper with a high cellulose content (87.0% or more) is that the shape of the resulting fibers is generally bent in the unbeaten state, so when it is made into a sheet, the straight fibers are not as stable. It can be said that it is more susceptible to changes in thermal history than aggregates.

Therefore, the present inventors focused on the fiber morphology of cellulose fiber pulp used as base paper for laminates, quantified the fiber morphology, and used it for management to obtain the target dimensional stability of laminates. It has been found that for fibers with bent bulbs, the dimensional stability can be improved by straightening the fiber shape by mechanical treatment using a beating machine, for example.

The degree of correction of the fiber morphology at this time is quantitatively quantified and managed using the degree of fiber bending.

The degree of fiber bending is expressed as the ratio of the actual length of one fiber to the short distance (straight line distance) connecting both ends of the long axis of the fiber, and is calculated using the following formula.

At this time, Lt: Actual fiber length Ls: Straight line distance connecting both ends of the fiber long axis, that is, for a completely straight fiber, Lt=Ls, and the fiber bending degree is 0 (zero). Furthermore, if both ends of the fiber are bent to the extent that they are close to each other, the degree of bending of the fiber becomes infinitely large.

There are no particular restrictions on the method for measuring the degree of fiber curvature;
00 or more] and find a representative value for the whole.

The degree of fiber bending of unbeaten raw materials for various cellulosic fiber pulps varies widely depending on the material type and valve manufacturing method, but the linter, sulfate dissolving valve, and sulfite dissolving pulp used in the base paper for laminates covered by this patent are Due to the refining process, the fiber form of unbeaten pulp is greatly bent, so the degree of fiber bending is as high as 50 to 80.

Therefore, it is disadvantageous in terms of dimensional stability when made into a laminate.

There are no restrictions on the method of reducing the degree of fiber bending in improving the dimensional stability of laminates and quantitatively controlling the fiber morphology. It is necessary to correct this.

As a method for this, for example, a beating machine can be used as one of the mechanical treatments.

However, the beating treatment to improve dimensional stability is a treatment to correct the bent fiber morphology, and it is inappropriate to control it only by the degree of beating, and it must also be controlled by the degree of fiber curvature. is important.

Even if the bulbs have the same beating degree, the dimensional stability of the resulting laminate will vary greatly if the fiber bending degree differs.

Beating treatment to correct the fiber morphology suppresses strong effects that prioritize cutting as much as possible, and uses small effects that cause deformation to loosen the internal structure of the fibers and soften the fiber bends, thereby correcting the fiber morphology. It is desirable to use a beating treatment that causes

In addition, in the beating process, in order to improve the permeability of the synthetic resin in the base paper for laminates, the r main shock of the pulp is
It is desirable that it is 00m/csF or more.

A pulp whose fiber curvature was reduced to less than 50 by correcting the fiber morphology through mechanical treatment, which previously demonstrated the high fiber curvature of linter and unbeaten sulfate-dissolving pulp and unbeaten sulfite-dissolving pulp, was used. The laminate made from the base paper for laminates has excellent punching workability and heat resistance, as well as greatly improved dimensional stability.

In the present invention, there are no particular restrictions on the basis weight and density of the base paper for laminates, but considering workability and productivity when processing into laminates, the basis weight and density of the base paper for laminates are 300g/1Wffi and 0.
, about 4 to 0.6 g/cm' is preferable.

Fillers, pigments, dyes, paper strength enhancers, flame retardant aids, flame retardants, etc. can be blended or added to the base paper for laminates of the present invention, if necessary. Moreover, there is no particular restriction on the method, and it is possible to select an appropriate method such as internal addition to paper stock and/or use of a size press.

The base paper for laminates using linter or dissolving pulp with reduced fiber bending degree thus obtained is then impregnated with a synthetic resin and laminated to form a laminate.

Resins for laminates include phenolic resin, melamine resin,
Thermosetting resins such as epoxy resins and unsaturated polyester resins, and thermoplastic resins such as fluororesins, polyester resins, and polyamide resins can be used.

A base paper for a laminate is impregnated with these resins to form a prepreg, which is then laminated and molded under heat to obtain a laminate. Known methods can be used for impregnation and hot lamination. The amount of resin impregnated is preferably in the range of 40 to 65% by weight based on the base paper.

Incidentally, a metal foil laminated laminate can be obtained by placing a metal foil on the surface of the laminate in which the prepregs are laminated and performing heating lamination molding.

Copper foil or aluminum foil can be used as the metal foil, and is not particularly limited. Further, if necessary, an adhesive may be applied to the back surface of the metal foil in advance.

(Function) The present invention focuses on the morphology of cellulose fibers and uses linter and dissolving pulp with reduced fiber bending to improve the dimensional stability of the laminate without reducing its punching processability and heat resistance. This is what we discovered.

Although there are many unknowns about the details of the effect of reducing the degree of fiber bending, in addition to the swelling of the fiber by water, the internal structure of the fiber is loosened by mechanical force, which softens the bending part of the fiber as well as the entire fiber. It is thought that the fiber morphology causes the correction.

It is believed that when the thus obtained linter and dissolving pulp paper with a low degree of fiber bending are used as a base paper for a laminate, the dimensional stability of the laminate is improved.

(Example) The fiber morphology is quantified by the degree of fiber bending, and by further reducing the degree of fiber bending, it is specifically explained by examples that a base paper for a laminate and a laminate with excellent dimensional stability can be obtained. However, the present invention is not limited thereto.

In the Examples and Comparative Examples, "%" means "% by weight" unless otherwise specified.

Example 1 The fiber tortuosity was reduced to 25 by beating unbeaten sulfate-dissolved hardwood pulp having a fiber tortuosity of 62.

Pulp at this time? The main shock was 550m/csF. The basis weight of base paper made using this raw material without adding any additives is 125g/ls''.

The density was 0.5 g/cta.

This base paper for laminates was impregnated with phenolic resin prepared with methanol to a solid content of 50%, dried to produce a prepreg with a resin adhesion of 50%, and 8 sheets of this prepreg were stacked at 160°C for 100 kg. / cm' = 60
The mixture was heated and pressure-molded for a minute to obtain a laminate having a thickness of 1.6 mm.

As shown in Table 1, the resulting laminate had excellent dimensional stability and other properties as well.

Example 2 The fiber tortuosity was reduced to 30 by beating unbeaten sulfite-dissolving softwood pulp having a fiber tortuosity of 74. The valve f main shock at this time was 600m/csF.

Thereafter, a laminate with a thickness of 1.6111 m was obtained in the same manner as in Example 1.

As shown in Table 1, the obtained laminate had good dimensional stability and other properties.

Comparative Example 1 Pulp unbeaten sulfate-dissolved hardwood pulp with fiber bending degree of 62? The main shock caused the ground to collapse to 560m/csF. The fiber bending degree at this time was 52. Thereafter, a laminate having a thickness of 1.6 a+m was obtained in the same manner as in Example 1.

The physical properties of the obtained laminate are also listed in Table 1, and the dimensional stability was inferior to that of Example 1.

Comparative Example 2 Pulp from unbeaten sulfite-dissolving pulp of softwood material with fiber bending degree of 74? During the main shock, it was beaten to 605a+/csF. The fiber bending degree at this time was 55. Thereafter, a laminate with a thickness of 1.6 nua was obtained in the same manner as in Example 2.

The physical properties of the obtained laminate are shown in Table 1, and the dimensional stability was inferior to that of Example 2.

Comparative Example 3 A laminate with a thickness of 1.6 mm was obtained in the same manner as in Example 1 using an unbeaten sulfate pulp of hardwood with a fiber bending degree of 18 and r of 580 m/csF in the same manner as in Example 1.

As shown in Table 1, the physical properties of the obtained laminate were very good in dimensional stability, but poor in punching workability.

(Left below) *l Using a push rod type thermal dilatometer, the load was 5g and the heating rate was 5℃/
Expansion from 50℃ to 150℃ under the conditions of 50℃ (cooling is allowed)
, cooling was carried out in the temperature range from 150°C to 50°C. The evaluation was expressed as an average value in the vertical and horizontal directions of the base paper.

*2 Die hole wall spacing is 0.8, 1.0.1.2゜1
．． 6mm diameter 1.0, 1.2, 1.7゜2, 1
Equipped with a pair of round holes of mm and a pair of square holes of 211111 mm, the clearance on one side between the punch and die is 0.05
The laminated board was punched using a test mold having a diameter of 1.5 mm and the surface temperature was varied, and the condition of the surface holes and cut edges after punching was judged according to ASTM D617 and evaluated in 4 stages.

*3 JIS C6481 and JIS K69
According to 11.

*4 The laminate was heated in a blow dryer for 5 minutes, and the maximum temperature at which no blistering occurred was indicated.

(Effect of the invention) In order to improve the dimensional stability of the laminate, we focused on the fiber morphology of the cellulose fibers used in the base paper for the laminate, and by controlling the fiber morphology by the degree of fiber bending, we improved the dimensional stability of the laminate. In addition, the degree of fiber bending can be improved by straightening the bent fiber morphology of high α-cellulose content pulps such as sulfate-dissolved pulp, sulfite-dissolved pulp, and linter paper in the unbeaten state. 50
By reducing the amount below, it became possible to produce base paper for laminates and laminates with excellent dimensional stability.

Patent Applicant President and Director of Sanyo Kokusaku Pulp Co., Ltd. Nagatsugu Kuramochi Procedural Amendment August 24, 1988 Commissioner of the Patent Office Yoshi 1) Takeshi Moon 1, Indication of Case Patent Application No. 1988-88243 2, Name and Dimensions of Invention Laminate base paper with good stability and laminate 3 using the same, relationship with the case of the person making the amendment Patent applicant address: 1-4-55 Marunouchi, Chiyoda-ku, Tokyo, scope of claims of the specification subject to amendment Column 6 of the detailed description of the invention,
Contents of amendment (1) The scope of claims is amended as shown in the attached sheet.

(2) Page 4, line 3, ``When I made a sheet.'' It says, ``When I made a sheet.'' (3) Page 4, line 8, ``Quantify and aim.'' It says, ``Quantify and aim.'' and (4) Page 4, line 17, “The shortest distance connected” is replaced by “The shortest distance connected” and (5) Page 9, line 4, “Decreased degree of bending” is replaced by “Decreased degree of bending.” (6) Page 9, line 14, "Dissolving pulp paper was used as a base paper for laminate boards.""Dissolving pulp paper was used as a raw material for base paper for laminate boards." (7) @ Page 14, line 2 says, ``Cooling is adjourned'', instead of ``cooling is left to cool,'' (8) Page 15, line 5, ``Like linter paper,'' says ``Linter's 5.''
and (9) page 15, line 8, ``reduced to less than 1'', respectively.

Attachment 2, Claim 1, A base paper for laminated boards with good dimensional stability using fiber flexure of less than 50/tar or sulfite dissolving valve and sulfite dissolving pulp.

2. The base paper for laminate boards according to claim 1, wherein the fiber bending degree is reduced by beating treatment.

3. A laminate having excellent punching workability, heat resistance, and dimensional stability, which is obtained by impregnating the base paper for laminates according to claim 1 or 2 with a resin for laminates and then heating and laminating the same.

Claims (1)

[Claims] 1. A base paper for laminated boards with good dimensional stability using linter, sulfate-dissolving pulp, or sulfite-dissolving pulp with a fiber bending degree of less than 50. 2. The base paper for laminate boards according to claim 1, wherein the fiber bending degree is reduced by beating treatment. 3. A laminate having excellent punching workability, heat resistance, and dimensional stability, which is obtained by impregnating the base paper for laminates according to claim 1 or 2 with resin for laminates and laminating the same under heating.