JP2001295191A - Aromatic polyamide fiber paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide new aromatic polyamide fiber paper which has excellent heat resistance, thermal dimensional stability and plybond strength, and does not cause the problem of electric insulation defect under high humidity. SOLUTION: This aromatic polyamide fiber paper in which at least one part of fibrids comprising an organic polymer is melted to bind para type aromatic polyamide staple fibers to each other, characterized in that the aromatic polyamide staple fibers and the fibrids comprising the organic polymer are contained in amounts of 40 to 97 wt.% and 3 to 60 wt.%, respectively, based on the total weight of the paper, in that >=50 wt.% of the total weight of the aromatic polyamide staple fibers comprise the para-type aromatic polyamide staple fibers, and in that at least one part of the para type aromatic polyamide fibers each has two mutually independent circular projections 1, 1 in the longitudinal direction and has a shape satisfying the expression: d1/d2>=1.1 wherein d1 is the maximum diameter of the circular protection portions, and d2 is the average diameter of a thin portion 2 for binding both the projections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic polyamide fiber paper, and more particularly to an aromatic polyamide fiber paper, which is excellent in heat resistance and electrical insulation, and particularly exhibits excellent effects when used in the production of laminates for electric circuit boards. To an aromatic polyester fiber paper.

[0002]

2. Description of the Related Art Heat-resistant, heat-resistant dimensional stability, moisture-resistant dimensional stability, electrical insulation, and deformation resistance (such as twisting, warping, and waving are unlikely to occur) in substrates used for laminates for electric circuit boards. ), And various properties such as lightness are required. Aromatic polyamide fiber paper is superior in terms of heat resistance, electrical insulation, heat-resistant dimensional stability, light weight, etc., compared to paper bases made of other materials. It has also been widely used as a base material for laminates for electrical circuit boards.

[0003] For example, a paper made of polymetaphenylene isophthalamide staple fiber (manufactured by Teijin Ltd., "Cornex") and polymetaphenylene isophthalamide pulp (fibrid): "electrically insulating paper" (Japanese Patent Laid-Open No. 236907/1990) Gazettes and JP-A-2-10684), polyparaphenylene terephthalamide staple fibers (manufactured by DuPont, "Kevlar") and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide staple fibers (Teijin ( Co., Ltd., Technora)
Polyamide fiber paper consisting of a resin and an organic resin binder: "Resin-impregnated sheet" (JP-A-1-92233) and a method for producing an aromatic polyamide paper (JP-A-2-47392)
Has been proposed.

[0004] However, although the former fiber paper is excellent in heat resistance, when heat treated at a high temperature of 250 ° C. or more, it not only shrinks to cause a dimensional change, but also an equilibrium moisture content of the fiber.
(Water content) is high and the content of impurity ions is high, so the electrical insulation is poor especially when held under high humidity for a long time. I can not use it.

On the other hand, the latter aromatic polyamide fiber paper has a low equilibrium moisture content and a relatively low impurity ion content, but uses only an organic resin as a binder component. As a result of the binder component migrating to the front and back sides of the paper and being unevenly distributed in the fiber paper manufacturing process, the amount of the binder component present in the middle layer of the paper becomes minute, and the thickness of the aromatic polyamide fiber paper in the thickness direction is reduced. There is a problem that uniformity is reduced and reliability is reduced.

Accordingly, when such an aromatic polyamide fiber paper is used as a base material for an electrical insulating material, the production process thereof, particularly, a prepreg preparation process of impregnating and drying a compounded varnish such as an epoxy resin, and a prepreg product, Impregnation amount of compounded varnish in the process of lamination molding (particularly in the thickness direction)
Or the amount of adhesion increases, or a part of the binder resin melts to cause a decrease in the adhesive strength between the fibers, causing the paper base material to cut, and furthermore, the short fibers are liable to move mutually. Therefore, there is a problem that the uniformity of the fiber density distribution is deteriorated, and the laminate for an electric circuit board is deformed particularly after the solder reflow process, which is performed at a high temperature, after completion of the process.

In order to solve such a problem, instead of using an organic resin as a binder component, a para-type aromatic polyamide short fiber (for example, manufactured by DuPont, ""Kevlar") and fibrillated para-type aromatic polyamide microfibers (for example, "Kevlar" manufactured by DuPont Co., Ltd.) combined with fiber paper "high-density para-aramid paper" (Japanese Unexamined Patent Publication No. 61-1605).
No. 00 publication) has been proposed. Although this paper has excellent properties such as heat resistance, heat-resistant dimensional stability, moisture-resistant dimensional stability, and deformation resistance (it is unlikely to cause twisting, warping, and waving), the meta-type aromatic used is There is a problem that the content of equilibrium moisture content and impurity ions is high in the production method of polyamide fibrid, and also in the structure of the fiber paper,
The fibril-filled microfibers fill the space between the para-type aromatic polyamide short fibers and are bonded by fibrids. There is a problem that the impregnating property of the varnish is reduced and partial unevenness is liable to occur, and there is a problem that the electrical insulation property under high humidity frequently becomes defective.

[0008]

The present invention is excellent in heat resistance, thermal dimensional stability, delamination strength, electrical insulation under high humidity, etc., and is particularly suitable as a base material for laminates for electric circuits. In addition, the above-mentioned problems which the conventional aromatic polyamide fiber paper had, especially the deformation (torsion, warping, waving, etc.) in the production process of the laminate for an electric circuit board are improved, and the electrical insulation under high humidity is improved. It is to provide a novel aromatic polyamide fiber paper in which the shortage problem is solved.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, as aromatic polyamide staple fibers constituting the aromatic polyamide fiber paper, the aromatic polyamide staple fibers have been formed in the length direction of the staple fibers. A para-type aromatic polyamide short fiber having at least two independent projections is bonded to a fibrid made of an organic polymer having binder properties to make paper, and a fibrid made of an aromatic polyamide is formed under high temperature and high pressure. Partially melted to tightly bond the short fibers constituting the paper into an aromatic polyamide fiber paper, and if necessary for the required characteristics of the application, a small amount of an organic resin binder was added as a bonding aid. The paper improves the paper properties after heating and pressing and the uniformity between paper layers,
The purpose of the present invention is to pay attention to improving the impregnating property and electric insulating property of the compounded varnish, and various properties to be provided in the laminate for electric circuit boards.

That is, according to the present invention, the aromatic polyamide staple fiber and the fibrid composed of an organic polymer are the main components, and at least a part of the fibrid composed of the organic polymer is melted. In an aromatic polyamide fiber paper obtained by bonding between the para-type aromatic polyamide short fibers, the aromatic polyamide short fibers are 4% of the total weight of the paper.
0 to 97% by weight of the fibrid comprising the organic high molecular weight polymer is in the range of 3 to 60% by weight of the total weight of the paper, and 50% by weight or more of the total weight of the aromatic polyamide short fibers is para-type aromatic. At least a portion of the para-aromatic polyamide short fibers is composed of polyamide short fibers and has at least two independent annular projections in its length direction, and the maximum diameter of each annular projection is d ₁ An aromatic polyamide fiber paper characterized in that the ratio of the average diameter of the thin portion connecting the protrusion to the projection: d ₂ has a shape satisfying d ₁ / d ₂ ≧ 1.1.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The aromatic polyamide fiber paper in the present invention is mainly made of an aromatic polyamide staple fiber and a fibrid composed of an organic high-molecular polymer, and is formed by adding an organic resin binder as an auxiliary as necessary. Paper-like material, non-woven fabric-like material or sheet-like material.

The aromatic polyamide staple fiber used in the present invention means that at least 80 mol% (preferably at least 90 mol%) of the repeating unit constituting the polyamide is an aromatic homopolymer represented by the following formula (1). It is a short fiber made of polyamide or aromatic copolyamide. Where Ar ₁ ,
Ar ₂ represents an aromatic group, particularly preferably an aromatic group composed of the same or different aromatic groups selected from the following formula (2). However, the hydrogen atom of the aromatic group may be substituted with a halogen atom, a lower alkyl group, a phenyl group, or the like.

[0013]

Embedded image

[0014]

Embedded image

The production method and fiber characteristics of such an aromatic polyamide fiber are described in, for example, British Patent No. 1501.
948, U.S. Patent Nos. 3,733,964, 3,767,756, 3,869,429,
JP-A-49-100322, JP-A-47-10863, JP-A-58-144152, JP-A-4-65513 and the like can be used.

Among the aromatic polyamide staple fibers, para-type aromatic polyamide staple fibers which are excellent in heat resistance include those in which the aromatic polyamide has coaxial or parallel chain bonds. And a short fiber made of polyamide facing in the opposite direction, for example, the Ar ₁ ,
A short fiber in which 80 mol% or more of Ar ₂ is an aromatic group represented by the following formula (A) and / or an aromatic group represented by the following formula (B) is exemplified.

[0017]

Embedded image

Specifically, polyparaphenylene terephthalamide staple fibers (for example, "Kevlar" manufactured by DuPont), copolyparaphenylene-3,4'-oxydiphenylene terephthalamide staple fibers (for example, Teijin (stock)
And "Technola"), and the like, and the latter is particularly preferable because it has a low content of impurity ions and thus has excellent electrical insulation.

In the present invention, meta-type aromatic polyamide short fibers may be included in a part of the aromatic polyamide short fibers. The meta-type aromatic polyamide short fibers used here are, among the aromatic polyamides described above, 50 of chain-bonded chains.
A mole% or more is a non-coaxial and non-parallel aromatic polyamide. For example, one or two or more of terephthalic acid and isophthalic acid as dicarboxylic acids and metaphenylenediamine and 4,4-diaminophenyl as diamines Short fibers made of homopolymers or copolymers using one or more of ether, 4,4'-diaminodiphenylmethane, xylylenediamine and the like can be mentioned. A typical example is polymetaphenylene. Short fibers of isophthalamide, polymeta-xylene terephthalamide, or copolymers obtained by copolymerizing isophthalic acid chloride, terephthalic acid chloride, metaphenylenediamine, etc., and among these, 80 mol% or more of the repeating unit , More preferably 90
It is preferable that the aromatic polyamide staple fiber whose mole% or more is metaphenylene isophthalamide is easily melted partially under high temperature and high pressure, and easily exerts a binder effect.

The proportion of the para-type aromatic polyamide short fiber used in the aromatic polyamide fiber paper of the present invention is such that the amount of the para-type aromatic polyamide short fiber is 50 to the total weight of the aromatic polyamide short fiber. It is important to make the weight% or more. When the amount of the para-type aromatic polyamide short fiber is 50,
When the amount is less than the weight percentage, the effect of the short fiber having the protrusion cannot be sufficiently obtained.

When the meta-type aromatic polyamide short fibers are used in the present invention, the draw ratio of the fibers in the production process of the meta-type aromatic polyamide short fibers is set to maximize the role as a binder. Desirably, the ratio is less than 5.0 times, and more preferably, less than 2.8 times, or an undrawn fiber is used. Among them, drawn fibers having a draw ratio in the range of 1.1 to 1.5 are most preferable.

In addition, it is desirable that the heat history is not given as much as possible in the process of producing the meta-type aromatic polyamide short fiber. The reason is that the higher the draw ratio in the manufacturing process, the more the heat history is received, the more the crystallization of the fiber proceeds, the more the above-mentioned softening, the tendency to melt becomes difficult to be exhibited, and the role as the binder is hardly exhibited. Because it becomes.

Some of the above-mentioned aromatic polyamide fibers show a tendency to shrink in the fiber axis direction and a tendency to elongate when water (moisture) contained in the fibers is subjected to dehydration (dehumidification) treatment by heating or the like. When the amount of these aromatic polyamide fibers is well controlled, dimensional changes hardly occur even after repeated washing and drying, and aromatic polyamide fiber paper excellent in heat-resistant dimensional stability and moisture-resistant dimensional stability is obtained. be able to.

Next, it is important that the para-type aromatic polyamide short fibers used in the present invention include those having a shape having two or more independent projections in the longitudinal direction. . Such protrusions can be formed by various methods.For example, spinning, drawing conditions (e.g., spinning discharge amount, spinning tension, drawing ratio, etc.) may be intermittently changed, or short fibers may be used. When cutting into pieces, the pieces can be cut while applying tension, and a projection can be formed using snapback at the time of cutting.

It is necessary that at least two protrusions are formed in one short fiber, and the maximum diameter of the protrusion is the average of the short fibers in the thin portion not including the protrusion. Those having a diameter 1.1 times or more are used.

FIG. 1 is a side view showing an example of a para-type aromatic polyamide short fiber used in the present invention. In FIG. 1, FIG. 1 (a) shows an example in which protrusions 1 are provided at both ends of a short fiber, and a thin portion of the short fiber connecting the protrusions 1 is shown.
The average diameter of the short fibers of No. 2 (hereinafter, referred to as a portion other than the protrusions):
d ₂ and the maximum diameter of the protrusion 1: ratio of d _1, as the d ₁
/ D ₂ ≧ 1.1 is satisfied.

The projections may be formed on portions other than the ends of the short fibers, but preferably formed near the ends of the short fibers (preferably near both ends). for example, the protrusions 1, as shown in the illustrated shown in FIG. 1 (b) distance from the end of the short fibers: are formed at the position of L _1, those wherein L ₁ is within 20% of the short fibers the overall length L is preferably .

The para-type aromatic polyamide short fibers having such protrusions may be mixed with a part of the para-type aromatic polyamide short fibers. It preferably accounts for at least 30% by weight of the weight. If the amount of the para-type aromatic polyamide short fibers having such projections is less than 30% by weight, a sufficient bonding effect may not be obtained, which is not preferable.

The single fiber fineness of such an aromatic polyamide short fiber is 0.33 to 5.56 dtex (0.3 to 5.5 dtex).
0de). The single fiber fineness is 0.3
If it is less than 3 dtex, there are many difficulties in the yarn-making technology, and not only is it difficult to stably produce fibers of good quality due to yarn breakage and fluff, but also the cost is high, which is not preferable. On the other hand, if it exceeds 5.56 dtex, the mechanical properties of the fiber, particularly the strength, are greatly reduced, which makes the fiber impractical. These aromatic polyamide staple fibers may be partially fibrillated mechanically, but if the proportion is too large, the impregnating property of the compounded varnish is impaired. So that
It is preferable to reduce the ratio as much as possible.

The fiber length of the aromatic polyamide short fibers is preferably in the range of 1 to 60 mm. Particularly, when the paper is formed by a wet method, the fiber length is 2 to 60 mm.
Those within the range of 12 mm are optimal. When the fiber length is less than 1 mm, the obtained aromatic polyamide fiber paper
It is not preferable because the mechanical properties of the (fiber aggregate) tend to be insufficient. On the other hand, when the fiber length exceeds 60 mm,
The uniformity of the fiber aggregate obtained by deteriorating the openability and dispersibility of the short fibers is impaired, and the mechanical properties tend to be insufficient.

It should be noted that other materials such as glass, polyether ether ketone, polyetherimide, polyphenylene sulfide, and ceramic short fibers are mixed within a range that does not impair the inherent properties of the aromatic polyamide short fibers. You may. In this case, the proportion of the aromatic polyamide short fibers in all the constituent fibers is 80% by weight or more, more preferably 90% by weight or more.

The fibrid comprising an organic high molecular polymer used in the present invention is a thin leaf-like or scale-like small piece having fine fibrils having a binder property, or a fibrillation at random in a wet papermaking process. Is a collective term for micro-short fibers, for example, Japanese Patent Publication No. 35-118.
No. 51, JP-B-37-5732, etc., by mixing an organic polymer solution with a precipitant of the polymer solution in a system having shearing force. Or a mechanical shearing force such as beating of a molded article having molecular orientation formed from a polymer solution having optical anisotropy by a method described in Japanese Patent Publication No. 59-603 or fibrid. And fibrids which are randomly fibrillated by applying the above method are preferable, and among them, the former method is most suitable.

As such an organic high molecular polymer,
Any fiber or a heat-resistant high-molecular polymer having a film-forming ability and having a thermal decomposition initiation temperature of 330 ° C. or higher can be used.

For example, aromatic polyamide, aromatic polyester, tehro-ring-containing aromatic polymer and the like can be used. Among them, polymetaphenylene isophthalamide ("Nomex", manufactured by DuPont) is particularly preferable. Preferably, copolyparaphenylene-3,4'-oxydiphenylene terephthalamide (manufactured by Teijin Limited, "Technola") having a low impurity ion content, p-hydroxybenzoic acid having a small equilibrium moisture content and 2 Polyester comprising a copolymer of 2,6-hydroxynaphthoic acid
(Kuraray Co., Ltd., "Vectran") is suitable, and especially when heat resistance is required, polyparaphenylene benzobisoxazole (Toyobo Co., Ltd., "PBO") is most suitable. is there.

The ratio of the fibrid comprising the organic high molecular polymer to the fiber paper of the present invention is 3 to 60.
%, Preferably 4 to 45% by weight, more preferably 5 to 30% by weight. When the mixing ratio of the fibrids is set relatively low, for example, Japanese Patent Publication No. 35-11851 or Japanese Patent Publication No.
It is preferable to use a fibrid obtained from the production method described in JP-A-7-5732, etc. In addition, when the mixing ratio is set relatively high, Japanese Patent Publication No. 59-603 is used.
It is preferable to use fibrids manufactured by the method described in Japanese Patent Application Laid-Open No. H10-209, and it is also possible to mix and use fibrids formed by both of these manufacturing methods.

The use of the fibrid according to the former method makes it possible to prepare an aromatic polyamide fiber paper having a high bulk density. Conversely, the use of the fibrid according to the latter method allows the preparation of an aromatic polyamide fiber paper having a low bulk density. Is possible, which fibrid to use, or
The mixing ratio of the two can be determined while checking the required characteristics of the intended laminate for an electric circuit board. In any case, if the mixing ratio of the fibrids is less than 3%, the tensile strength required for paper formation in the wet papermaking process cannot be maintained, and if it exceeds 60% by weight, the bulk density of the obtained aromatic polyester fiber paper will be increased. (The upper limit of the preferred range of the bulk density shown below: 1.13 g / cm ³⁾
), Which impairs the impregnation of the compounded varnish, which is not preferred.

As described above, some aromatic polyamide fibers have a tendency to elongate or shrink in the fiber axis direction when dehydrating (dehumidifying) water (moisture) contained in the fibers by heating or the like. Although there are fibers that show, among the fibrids made of organic polymer, among the fibrids that show a tendency to shrink or elongate in the lengthwise direction of the thin leaf-like or scaly shape under the same treatment, By combining both well, similarly to the above, an aromatic polyamide fiber paper which is hardly changed in dimensions even after repeated washing and drying, and is excellent in heat-resistant dimensional stability and moisture-resistant dimensional stability can be obtained.

The fibrid made of the organic high molecular polymer has a function as a binder for binding short fibers in a wet papermaking process, and its binding force (adhesive force) is a thermosetting resin, For example, epoxy resin,
Since it is inferior to phenolic resins, polyurethane resins, melamine resins, formaldehyde resins, fluoropolymer resins, etc., a small amount of a water-dispersed binding aid selected from the group consisting of these thermosetting resins is added to form a wet papermaking process. Papermaking performance can be improved. (In this case, since the binding aid is used as a substitute for fibrids,
Reduce the amount of fibrids by the amount of binding aid added). In particular, a resin using a water-dispersible epoxy resin having an epoxy functional group in the molecule has a good compatibility with the compounding varnish used in the prepreg process and is optimal.

The ratio of the binding aid in the aromatic polyamide fiber paper of the present invention is not more than 1/3, more preferably not more than 1/4, of the weight of the fibrid comprising the organic polymer. Those used in the following ranges are preferred. The ratio of the binding aid is 1/3 of the weight of the fibrid.
If it exceeds, the fibrid may not be able to suppress the migration phenomenon in the wet papermaking process, which may cause the interlayer adhesion between the front and back sides of the paper and the middle layer to become non-uniform. This is not preferable because the short fiber orientation or the uniformity of the fiber density distribution may be reduced.

The aromatic polyamide fiber paper described above can be produced by a conventionally known method.
The aromatic polyamide short fibers are weighed so as to have a predetermined ratio, and are charged and uniformly dispersed in water such that the fiber concentration is in a range of about 0.15 to 0.40% by weight. In addition, if necessary, after adding a dispersing agent and a viscosity modifier, a wet papermaking method is performed by a wet papermaking method using a paper machine such as a long net or a round net, and if necessary, an organic if necessary. -Based binder resin is applied to a weight of a predetermined solid content ratio by a spray method or the like, and then the dried paper obtained by drying is heated and pressed so as to be in a predetermined bulk density range to obtain an aromatic polyamide. Fiber paper can be obtained.

For example, when the heating and pressurizing process is performed by using a calender, one hard surface roll having a diameter of about 15 to 80 cm and one surface deformable elastic roll having a diameter of about 30 to 100 cm are used. Or more preferably between two hard surface rolls having a diameter of about 20-80 cm. In that case, in order to soften or partially melt the fibrid comprising the meta-type aromatic polyamide short fiber or the organic polymer to sufficiently exhibit the function as a binder component, it is necessary to use 220 to 400.
C. is carried out in a temperature range of, preferably, 250 to
Excellent bonding results can be obtained by performing at a temperature of 350 ° C, more preferably 280 ° C to 330 ° C. The pressure is 147 to 245 daN / cm (150 to 25
0 kg / cm), and preferably at a linear pressure in the range of 176.4 to 245 daN (180 to 250 kN).
g / cm). The heating and pressurizing process using the calender may be performed in a single-stage process of a calendering machine. However, in order to obtain a more uniform paper in the thickness direction, a two-stage process of a calendering machine that performs preliminary heating and pressurizing process may be performed. You can do it.

By the heating and pressurizing treatment, the bulk density of the aromatic polyamide fiber paper is 0.45 to 1.13 g.
/ Cm ³ , preferably 0.50 to 0.88 g / cm ³ ,
More preferably, the bulk density of the paper can be adjusted and controlled in the papermaking process so as to fall within the range of 0.55 to 0.75 g / cm ³ .

In the production of a laminate for an electric circuit board, there is usually a step of heat treatment at a high temperature of about 220 ° C. Therefore, a heat history not lower than the heat treatment temperature is given to the aromatic polyamide fiber paper in advance. Otherwise, a change in the thermal dimensions and internal strain of the aromatic polyamide fiber paper will occur during the heat treatment step, and this will undesirably cause a problem of lowering the dimensional stability under heat and the resistance to deformation. Therefore, in the present invention, the temperature: 280 ° C. to 330
° C, linear pressure: 176.4 to 245 daN (180 to 250
(kg / cm) is optimally calendered. The aromatic polyamide fiber paper produced under these conditions has a thermal dimensional change rate of, for example, 280 ° C. × 5 minutes after heat treatment. 0.30% or less, excellent in heat-resistant dimensional stability, bulk density is in the range of 0.55 to 0.75 g / cm ³ , and tensile strength and delamination strength are higher than the above-mentioned properties. Aromatic polyamide fiber paper that can sufficiently satisfy various properties required in a laminate for use and its manufacturing process. The heating and pressurizing condition is 400 ° C., 245
If it exceeds daN / cm (250 kg / cm), the bulk density of the obtained paper exceeds 1.13 g / cm ^3, which is not preferable. Further, by the heating and pressurizing treatment, crystallization of the short fibers constituting the paper proceeds, and the water absorption of the obtained aromatic polyamide fiber paper is reduced, and the equilibrium water content can be reduced to 3% or less. is there.

When the equilibrium moisture content of the aromatic polyamide staple fiber is too high (for example, 7% or more), the equilibrium moisture content of the aromatic polyamide fiber paper obtained even when subjected to the heat and pressure processing exceeds 3%. (If the equilibrium moisture content exceeds 3%, the electrical properties such as insulation are adversely affected, which is not preferable.) For use as a base material for laminates for electric circuit boards, aromatic polyamide short fibers or fibrids are required. Care must be taken in the selection and blending ratio.

The equilibrium moisture content of the aromatic polyamide fiber paper is measured by the following method according to JIS, L-1013. That is, an aromatic polyamide fiber paper obtained by wet papermaking and then subjected to heat and pressure processing is treated at a temperature of 12 ° C.
After being absolutely dried in an atmosphere of 0 ° C., the weight of the aromatic polyamide fiber paper in the absolutely dried state was measured, and further prepared for 72 hours in an atmosphere of a temperature of 20 ° C. and a relative humidity of 65% RH. The weight of the aromatic polyamide fiber paper is measured to calculate the ratio to the weight of the aromatic polyamide fiber paper in the absolutely dry state, and this is expressed as a percentage (%) to obtain an equilibrium moisture content.

[0046]

The aromatic polyamide fiber paper of the present invention has at least two protruding portions in which at least a part of the para-type aromatic polyamide short fibers among the short fibers constituting the paper are independent of each other in the longitudinal direction. Therefore, the short fibers are strongly bonded to each other. That is, in comparison with the conventional short fiber having a uniform thickness, in the case of using the short fiber having the protruding portion, the pulling resistance of the fiber in the paper is significantly increased, and the reinforcing effect is greatly improved. It is inferred that

The aromatic polyamide fiber paper of the present invention has a relatively low bulk because both the fibrid having a relatively short length and the water-dispersing type binding agent have a function as a binder. It has high tensile strength and high delamination strength even at high densities, and its dimensional change with respect to heat, temperature, and humidity in the thickness and plane directions of the paper is small, despite its low bulk density. It is good for the bulk density, and enables the formation of a highly uniform laminate with little movement of short fibers in the press lamination molding process.

[0048]

As described above, the aromatic polyamide fiber paper of the present invention thus obtained has various properties which were obtained when the aromatic polyamide fiber paper produced by the prior art was used for laminates for electric circuit boards. Aromatic polyamide fiber with high tensile strength and high delamination strength, in which problems, especially dimensional changes due to changes in temperature and humidity, are reduced, and water absorption (equilibrium moisture) is reduced to improve electrical insulation. I got the paper.
The laminate for an electric circuit board using the aromatic polyamide fiber paper as a base material has little twisting, warping, waving, or the like in its manufacturing process or application, so that a fine circuit can be designed and lead can be obtained. It is an epoch-making product that can maintain high reliability for a long time even when soldering electronic components with a small coefficient of temperature and humidity expansion such as a ceramic chip carrier (LCCC) and a bare chip directly.
The aromatic polyamide fiber paper of the present invention is suitable as a base material of a laminate for an electric circuit board in applications requiring a high degree of lightness, a high degree of heat resistance, moisture resistance, and dimensional stability, and electrical insulation.

[0049]

The present invention will be described in more detail with reference to the following examples. In addition, the preparation method of the test piece used in the Example and the evaluation method thereof were based on the following methods.

<Method for Preparing Specimen> (1) Production of Para-Type Aromatic Polyamide Fiber Having Protrusion A predetermined fiber diameter (fineness: 0.33 to 5.56 dtex (0.
The aromatic polyamide fibers spun in the range of 3 to 5.0 de) are drawn together while applying water to a total fineness of about 11.
It is bundled to 10,000 dtex (100,000 de), and the desired length (2
１２12 mm) by cutting at both ends (cut portion) of the cut end of the short fiber, or near the both ends, the maximum diameter of the annular protrusion: d ₁ and the average of the thin portion of the short fiber connecting the protrusion. An aromatic polyamide short fiber on which two annular protrusions were formed such that the ratio to the diameter: d ₂ : d ₁ / d ₂ was 1.1 or more was obtained.

On the other hand, the ratio of the end of the cut end of the short fiber: d ₃ to the average diameter of the center of the short fiber: d ₂ : d ₃ / d ₂ is 1.0.
In order to obtain short fibers of less than 5, a predetermined fiber diameter
(Fineness: 0.33 to 5.56 dtex) The aromatic polyamide fibers spun to a density of 0.33 to 5.56 dtex are aligned while applying water, and bundled so that the total fineness is about 111,000 dtex (100,000 de). An aromatic polyamide short fiber (for comparison) was obtained by cutting to a target length (2 to 12 mm) with a cutter rotating at a high speed (blade edge speed: 5 m / min or more).

(2) Preparation of fiber paper The aromatic polyamide staple fiber prepared in the above (1),
Dispersed in water using an aromatic polyamide short fiber and a fibrid composed of an organic high-molecular polymer described in each of the following examples, and formed by a known method, and the paper was dried at a temperature of 110 ° C. Further, with a calender device having a pair of metal rolls, the temperature: 200 ° C. to 350 ° C.,
A calendar treatment was performed under the conditions of a linear pressure of 196 daN / cm (200 kg / cm) and a calendar speed of 4 m / min to obtain an aromatic polyamide fiber paper.

(3) Preparation of Prepreg The aromatic polyamide fiber paper obtained in the above (2) is used as a base material, and the base material is impregnated with a resin varnish. As the impregnated resin varnish, a thermosetting resin is used as a main component of the resin, and a curing agent, a catalyst, and the like are dissolved and mixed in a solvent to adjust the viscosity to an appropriate level. As an impregnation method, the base material is continuously impregnated with the resin varnish, and dried using a coating machine for drying a solvent to obtain a prepreg.

(4) Preparation of Printed Wiring Board An electrolytic copper foil having a thickness of 35 μm is laminated on both sides of the prepreg obtained in the above (3), pressure: 20 to 50 kg / cm ² , lamination temperature: 0 to 260 ° C. Perform thermocompression treatment for 60 minutes in the range,
The lamination temperature at this time is changed according to the type of the impregnated resin used and the difference in the curing temperature.

<Evaluation Method of Test Piece> (5) Ratio of Maximum Diameter of Protrusion Portion A 100 aromatic polyamide short fibers were observed with an optical microscope, and for each short fiber, the maximum diameter of the annular protrusion: d ₁ . diameter thin portion connecting the annular projections: measure and d _2, obtains the d ₁ / d _2, calculate the average from 100 d ₁ / d _2.

(6) Bulk density of paper Measured according to JIS C-2111 6.1.

(7) Tensile Strength of Paper The tensile strength was measured by a method according to JIS C-2111-7 using a constant-speed elongation type tensile tester.

(8) Paper delamination strength A 200 mm length and 15 mm width were measured using a constant speed elongation type tensile tester.
The strength (9.8 mN / 15 mm) when the intermediate layer portion of the mm sample was peeled in a T-shape was measured.

(9) Rate of thermal dimensional change of paper Using a high-precision two-dimensional coordinate measuring machine (manufactured by Mutou Kogyo Co., Ltd.), the length direction of a sample having a length of 250 mm and a width of 50 mm was measured at a temperature of 280 ° C. before heat treatment. The length after the heat treatment for 5 minutes was measured, and the thermal dimensional change was calculated by the following formula. In addition, the sample for measurement was taken from the length direction and the width direction of the continuous paper and measured, and the average value was compared and determined.

[0060]

(Equation 1)

(10) Amount of Warpage of Printed Wiring Board The above-mentioned three prepregs were stacked and subjected to hot press treatment, and then a cured board from which the copper foil of a 200 mm square double-sided copper-clad laminate was removed was placed on a surface plate. Then, the amount of warpage at the point where the amount of lift is the largest at the four corners of the cured substrate is measured.

(11) Insulation resistance value under high humidity High purity brominated bisphenol A type epoxy resin and orthocresol novolak type epoxy resin are added with dicyandiamide as a curing agent and 2-ethyl- as a curing accelerator.
After dissolving an epoxy resin composition containing 4 methyl imidazole in a mixed solution of methyl ethyl ketone and methyl cellosolve and impregnating the aromatic polyamide fiber paper with the varnish, a temperature of 110 to 120 ° C. and a temperature of 5 to 10 ° C. After drying for minutes, a B-stage prepreg paper having a resin content of 55% by volume was prepared. Thickness of the prepreg paper: 1
Laminated on both sides of an 8μ copper foil, and further laminated the same copper foil on the outside, and 170 ° C. under reduced pressure by hot pressing
Pressing was performed under the conditions of × 40 kg / cm × 50 minutes, the resin was cured to form a laminate for an electric circuit board, and further subjected to a curing treatment in a hot air dryer at a temperature of 200 ° C. for about 20 minutes. On one surface of the laminate for an electric circuit board, a comb electrode pattern at an interval of 0.15 mm is formed by etching, and a DC voltage of 35 V is applied between the comb electrodes in an atmosphere at a temperature of 60 ° C. and a relative humidity of 95% RH. It was stored for 1000 hours while applying voltage. Next, the comb-shaped electrode is stored for 1 hour in an atmosphere at a temperature of 20 ° C. and a relative humidity of 60% RH, and a DC voltage (35 to 90 V) is applied between the comb-shaped electrodes for 60 seconds to obtain an insulation resistance value (Ω / Ω). cm).

Example 1 Single-fiber fineness of copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide as aromatic polyamide short fiber: 1.67
dtex (1.5 de), cut length: 3 mm, equilibrium moisture content: 1.8%, short fiber (manufactured by Teijin Limited, "Technola"): 9
Polymetaphenylene isophthalamide (Dupont) as a fibrid composed of 0% by weight and an organic polymer.
Fibrid consisting of "Nomex" manufactured by Co., Ltd .: 10
% By weight, disintegrated and dispersed in water with a pulper, and dispersant (Matsumoto Yushi Co., Ltd.) so that the concentration becomes 0.03%.
(YM-80)) was added to prepare a papermaking slurry liquid in which short fibers for papermaking having a fiber concentration of 0.20% by weight and fibrids were dispersed.

However, the short fiber composed of copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide, which is an aromatic polyamide short fiber, is obtained by using a guillotine cutter as described in (1) above to obtain d ₁ / d. Those cut so that ₂ = 1.15 were used.

Next, using a tappy type square hand machine, papermaking was performed using the slurry for papermaking, lightly dewatered under pressure, and dried in a hot air dryer at a temperature of 160 ° C. for about 15 minutes. An aromatic polyamide fiber paper was obtained. Then, about 400mm in diameter
After heating and pressurizing at a temperature of 230 ° C. and a linear pressure of 160 kg / cm using a calender comprising a pair of hard surface metal rolls, the above-mentioned fibrid made of polymetaphenylene isophthalamide is softened and partially melted. Then, in order to strengthen the adhesion with copolyparaphenylene / 3,4'-oxydiphenylene / terephthalamide short fiber, a high-temperature high calender machine consisting of a pair of hard surface metal rolls having a diameter of about 500 mm was used. : 32
It was heated and pressed under the conditions of 0 ° C. and a linear pressure of 200 kg / cm to obtain an aromatic polyamide fiber paper having a desired basis weight of 72 g / m ² .

The equilibrium water content of the aromatic polyamide fiber paper was 1.9%. In addition, various characteristics evaluated by the above-described measurement methods for other characteristics are as shown in Table 3. Further, using the aromatic polyamide fiber paper, a varnish is impregnated with the compounded varnish according to the method described above to prepare a prepreg paper, and the laminate for an electric circuit board prepared using the prepreg paper is subjected to a long-term operation under high humidity. The insulation resistance after storage for a time was measured. Table 3 shows the results.

Example 2 As an aromatic polyamide short fiber, single fiber fineness composed of polyparaphenylene terephthalamide: 1.58 dtex (1.42 de), cut length:
An aromatic polyamide fiber paper was obtained in the same manner as in Example 1 except that 3 mm short fibers (manufactured by DuPont, "Kevlar"): 90% by weight were used.

The properties of this paper evaluated in the same manner as in Example 1 are shown in Table 3. Also,
Using the aromatic polyamide fiber paper, the varnish is impregnated with the compounded varnish according to the method described above to prepare a prepreg paper, and the laminate for an electric circuit board prepared using the prepreg paper is subjected to high humidity for a long time. The insulation resistance value after storage was measured. The results are shown in Table 3.

Example 3 As an aromatic polyamide short fiber, single fiber fineness of copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide: 1.67
dtex (1.5 de), cut length: 3 mm, equilibrium water content: 1.8%, short fiber (manufactured by Teijin Limited, "Technola"): 7
Consists of 5% by weight and polymetaphenylene isophthalamide, the draw ratio in the production process is 1.4 times, and the single fiber fineness is:
3.33 dtex (3.0 de), cut length: 6 mm, short fiber (manufactured by Teijin Limited, “Cornex”): 15% by weight, and further from the organic polymer used in Example 1. A fibrid composed of polymetaphenylene isophthalamide (manufactured by DuPont, "Nomex") was used in the same manner as in Example 1 except that 10% by weight of the fibrid was used to obtain a target aromatic polyamide fiber paper. Was.

The properties of this paper evaluated in the same manner as in Example 1 are as shown in Table 3. Further, for the laminate for an electric circuit board prepared by using the aromatic polyamide fiber paper in the same manner as in Example 1, the deformation amount and the insulation resistance under high humidity evaluated by the same method as in Example 1 are as follows. As shown in Table 3.

Example 4 In Example 3, 8% by weight of a fibrid made of polymetaphenyleneisophthalamide ("Nomex", manufactured by DuPont) was used as a fibrid made of an organic polymer. further,
At the time of papermaking, a water diluent (solid content: 2% by weight) of a bisphenol A epichlorohydrin type water-dispersible epoxy resin binder (manufactured by Dainippon Chemical Co., Ltd.) is used, and the solid content of the resin becomes 2% by weight. An aromatic polyamide fiber paper was obtained in the same manner as in Example 3 except that the spraying was carried out as described above.

The properties of this paper evaluated in the same manner as in Example 1 are as shown in Table 3. Further, using the aromatic polyamide fiber paper, by the method described above,
A prepreg paper was prepared by impregnation with the compounded varnish, and the insulation resistance value of the laminate for an electric circuit board prepared using the prepreg paper after being stored for a long time under high humidity was measured. The results are shown in Table 3.

Example 5 As an aromatic polyamide short fiber, single fiber fineness of copolyparaphenylene / 3,4′-oxydiphenylene terephthalamide: 1.67
dtex (1.5 de), cut length: 3 mm, equilibrium moisture content: 1.8%, short fiber (manufactured by Teijin Limited, "Technola"): 9
0% by weight, as a fibrid composed of an organic high molecular polymer, 7% by weight of a fibrid composed of polymetaphenylene isophthalamide (manufactured by DuPont, "Nomex"), and bisphenol A epichlorohydrin was used during papermaking. Water Dispersion Solution (Solid Content: 2)
(% By weight) was sprayed such that the solid content of the resin was 3% by weight, to obtain the desired aromatic polyamide fiber paper.

The properties of this paper evaluated in the same manner as in Example 1 are as shown in Table 3. Further, using the aromatic polyamide fiber paper, by the method described above,
A prepreg paper was prepared by impregnation with the compounded varnish, and the insulation resistance value of the laminate for an electric circuit board prepared using the prepreg paper after being stored for a long time under high humidity was measured. The results are shown in Table 3.

Example 6 As an aromatic polyamide short fiber, single fiber fineness of copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide: 1.67
dtex (1.5 de), cut length: 3 mm, equilibrium moisture content: 1.8%, short fiber (manufactured by Teijin Limited, "Technola"): 9
Example except that 8% by weight of fibrid (manufactured by Teijin Limited) composed of copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide was used as the fibrid composed of 2% by weight and the organic polymer. In the same manner as in Example 1, an aromatic polyamide fiber paper was obtained.

The properties of this paper evaluated in the same manner as in Example 1 are as shown in Table 3. Further, using the aromatic polyamide fiber paper, by the method described above,
A prepreg paper was prepared by impregnation with the compounded varnish, and the insulation resistance value of the laminate for an electric circuit board prepared using the prepreg paper after being stored for a long time under high humidity was measured. The results are shown in Table 3.

Example 7 As an aromatic polyamide short fiber, single fiber fineness of copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide: 1.67
dtex (1.5 de), cut length: 3 mm, equilibrium moisture content: 1.8%, short fiber (manufactured by Teijin Limited, "Technola"): 9
2% by weight, and 5% by weight of a fibrid (manufactured by Teijin Limited) composed of copolyparaphenylene / 3,4′-oxydiphenylene / terephthalamide as a fibrid composed of an organic polymer. At the time of papermaking, a water diluent (solid content: 2% by weight) of a bisphenol A epichlorohydrin type water-dispersible epoxy resin binder (manufactured by Dainippon Chemical Co., Ltd.) was reduced to 3% by weight of the resin. The same procedure as in Example 1 was carried out except that spraying was performed so as to obtain a target aromatic polyamide fiber paper.

The properties of this paper evaluated in the same manner as in Example 1 are as shown in Table 3. Further, using the aromatic polyamide fiber paper, by the method described above,
A prepreg paper was prepared by impregnation with the compounded varnish, and the insulation resistance value of the laminate for an electric circuit board prepared using the prepreg paper after being stored for a long time under high humidity was measured. The results are shown in Table 3.

Comparative Example 1 As an aromatic polyamide fiber, single fiber fineness of copolyparaphenylene / 3,4′-oxydiphenylene terephthalamide: 1.67
dtex (1.5 de), cut length: 3 mm, equilibrium water content: 1.8%, short fiber (manufactured by Teijin Limited, "Technola"): 7
5% by weight and polymetaphenylene isophthalamide, the draw ratio in the production process is 1.4 times, short fiber fineness: 3.33 dtex (3.0 de), cut length: 6 mm
15% by weight of staple fiber (manufactured by Teijin Limited), and as a fibrid made of an organic polymer, polymetaphenylene isophthalamide (manufactured by DuPont, "Nomex") ) Consisting of:
When preparing a papermaking slurry using 10% by weight, as a short fiber composed of the copolyparaphenylene / 3,4'-oxydiphenylene / terephthalamide, a d is rotated by a cutter rotating at a cutting edge speed of 8 m / min. ₁ / d ₂ = 1.0
Aromatic polyamide fiber paper was obtained by using the material cut to be 2.

The properties of this paper evaluated in the same manner as in Example 1 are as shown in Table 3. Further, for the laminate for an electric circuit board prepared by using the aromatic polyamide fiber paper in the same manner as in Example 1, the deformation amount and the insulation resistance under high humidity evaluated by the same method as in Example 1 are as follows. As shown in Table 3.

Table 1 shows the main components of the aromatic polyamide fiber paper shown in Examples 1 to 7 and Comparative Example 1, and Table 2 shows Examples 1 to 7 and Comparative Example 1. for aromatic polyamide staple fibers used in the aromatic polyamide fiber sheet as shown, the maximum diameter of the projections: d ₁ and the diameter of the portion other than the protruding portion: shows the ratio of d _2.

[0082]

[Table 1]

[0083]

[Table 2]

[0084]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a side view showing an example of a para-type aromatic polyamide short fiber used in the present invention.

[Explanation of symbols]

 1 annular protrusion 2 part connecting annular protrusion

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Torukei Matsui 3-4-1, Amihara, Ibaraki-shi, Osaka Teijin Limited Osaka Research Center F-term (reference) 4L055 AF35 AF46 AG69 AG78 AG79 AG81 AG87 EA15 FA13 FA18 FA19 GA02

Claims (4)

[Claims] 1. An aromatic polyamide short fiber and an organic polymer
A fibrid comprising a polymer as a main component;
At least a part of the fibrid composed of a high-molecular polymer is
By melting and bonding between the para-type aromatic polyamide short fibers
The aromatic polyamide fiber paper
Mid staple fiber is 40-97% by weight of the total weight of paper, organic high
The fibrid composed of a molecular polymer is 3 to 6% of the total weight of the paper.
0% by weight, and the total weight of the aromatic polyamide short fibers
50% by weight or more of the amount is para-type aromatic polyamide short fiber
And a small amount of said para-type aromatic polyamide short fibers.
At least some are independent from each other in the length direction.
And the maximum diameter of each annular projection: d₁And rush
Average diameter of the thin part connecting the starting parts: d_TwoAnd d is ₁/ D
_TwoHaving a shape satisfying ≧ 1.1
Aromatic polyamide fiber paper. 2. The fiber length of the aromatic polyamide short fiber is 2
The aromatic polyamide fiber paper according to claim 1, which is in a range of from 12 mm to 12 mm. 3. The staple fiber of para-type aromatic polyamide is a staple fiber composed of polyparaphenylene terephthalamide or a staple fiber composed of copolyparaphenylene / 3,4′-oxydiphenylene terephthalamide.
Or the aromatic polyamide fiber paper according to 2. 4. A group consisting of an epoxy resin, a phenol resin, a melamine resin, a formaldehyde resin and a fluoropolymer resin, wherein not more than one-third of the total weight of the fibrid comprising the organic polymer in the aromatic polyamide fiber paper is used. The aromatic polyamide fiber paper according to any one of claims 1 to 3, wherein the aromatic polyamide fiber paper is formed by replacing with at least one kind of a water-dispersion type binding aid selected from the group consisting of: