JP2000226789A - Aromatic polyamide fiber paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aromatic polyamide fiber paper excellent in heat resistance and dimensional stability against heat and especially suitable as a substrate of laminate for electric circuits, in which deformation (e.g. twisting, warping or waving) in production process of the laminate is solved, having good laser processing property. SOLUTION: In this aromatic polyamide fiber paper consisting essentially of a para-aromatic polyamide short fiber and a thermoplastic resin short fiber having >=220 deg.C softening temperature and an organic binder, an amount of para-aromatic polyamide short fiber occupied in total weight of the paper is 50-95 wt.% and the para-aroamtic polyamide short fiber is composed of 5-95 wt.% homopolymer and 5-95 wt.% copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an aromatic polyamide fiber paper which has excellent heat resistance and dimensional stability and can be suitably used particularly for producing a laminate for an electric circuit board.

[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. That is, various properties such as laser workability and light weight during via formation are required. Aromatic polyamide fiber paper is superior in heat resistance, electrical insulation, heat resistance dimensional stability, light weight, etc., compared with paper base made of other materials. Is being used as a base material.

For example, polymetaphenylene isophthalamide staple fiber (Cornex; manufactured by Teijin Limited) and polymetaphenylene isophthalamide pulp (fibrid)
"Aromatic polyamide fiber paper (Japanese Unexamined Patent Publication No. 2-23)
6907 and JP-A-2-106840) ",
Polyparaphenylene terephthalamide staple fiber (Kevlar; manufactured by DuPont) and copolyparaphenylene
Aromatic polyamide fiber paper consisting of 3,4'-oxydiphenylene / terephthalamide staple fiber (Technola; manufactured by Teijin Limited) and an organic resin binder such as "resin impregnated sheet (JP-A-1-92233)" and aromatic polyamide A method for producing fiber paper (Japanese Patent Laid-Open No. 2-47392) and the like have been proposed.

However, when the fiber paper is heat-treated at a high temperature of 250 ° C. or higher, it not only shrinks to cause dimensional change, but also has a high equilibrium moisture content (water content) and a high impurity ion content. Because of its large amount, it is inferior in electrical insulation, especially when held under high humidity for a long period of time, and therefore cannot be used as an electrical insulating base material that requires high reliability.

On the other hand, the latter fiber paper is excellent in terms of the equilibrium moisture content of the fiber and the content of impurity ions, but uses only an organic resin as a binder component, and thus is not used in the fiber paper manufacturing process. As a result of the binder component migrating to the front and back sides of the paper and being unevenly distributed, the amount of the binder component present in the middle layer of the paper becomes very small, and the uniformity in the thickness direction of the obtained fiber paper is reduced, and the reliability is deteriorated. There is a problem of doing.

When such a fiber paper is used as a base material of a laminate for an electric circuit board, its manufacturing process, particularly, a prepreg process of impregnating and drying a compounded varnish such as an epoxy resin and a process of laminating the prepreg product, etc. As a result, the dispersion of the impregnation amount (particularly in the thickness direction) and the adhesion amount of the compounded varnish increases, or a part of the binder resin is melted to lower the adhesive strength between the fibers, thereby causing the paper base material to cut. In addition, the short fibers tend to move easily with each other, so that the uniformity of the fiber density distribution is deteriorated. In particular, there is a problem that the laminate for an electric circuit board is deformed after the solder reflow process which is performed at a high temperature. It was not preferred.

In addition, instead of using an organic resin as a binder component, a meta-type aromatic polyamide fibrid is used, and para-type aromatic polyamide short fibers (for example, Kevlar; manufactured by Dupont KK) are fibrillated and para-type aromatic. Fiber paper "high-density para-aramid paper (Japanese Patent Application Laid-Open No. 61-160500)" which has been bonded to microfibers of aromatic polyamide (for example, Kevlar; manufactured by DuPont) has been proposed.

[0008] The fiber paper has heat resistance, heat-resistant dimensional stability,
Although properties such as moisture-resistant dimensional stability and deformation resistance (it is unlikely to cause twisting, warping, and waving) are improved, since the constituent short fibers are short fibers made of a homopolymer,
When a via is formed using a carbon dioxide gas laser or the like, there is a problem that many irregularities are formed on the inner wall of the via, and the irregularities remain as they are even after the plating process. This improvement is strongly desired.

[0009]

The present invention is excellent in heat resistance and electrical insulation under high humidity, and is particularly suitable as a base material for laminates for electric circuit boards. Problems, especially deformation (torsion, warping, waving, etc.) in the manufacturing process of laminates for electric circuit boards
It is an object of the present invention to provide a novel aromatic polyamide fiber paper which can solve the problem of insufficient electrical insulation under high humidity and laser workability.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, as a para-type aromatic polyamide short fiber constituting an aromatic polyamide fiber paper,
It has been clarified that a desired aromatic polyamide fiber paper can be obtained by mixing a short fiber composed of a homopolymer and a short fiber composed of a copolymer.

Thus, according to the present invention, there is provided an aromatic polyamide fiber paper containing a para-type aromatic polyamide short fiber, a thermoplastic resin short fiber having a softening temperature of 220 ° C. or higher, and an organic binder as main components. The amount of the para-type aromatic polyamide staple fiber in the total weight is 50 to 95% by weight, and the para-type aromatic polyamide staple fiber is 5 to 5% of the total weight of the aromatic polyamide staple fiber. 9
An aromatic polyamide fiber paper is provided, which comprises 5% by weight of short fibers composed of a homopolymer and 5 to 95% by weight of short fibers composed of a copolymer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The aromatic polyamide fiber paper according to the present invention includes a para-type aromatic polyamide short fiber, a thermoplastic resin short fiber having a softening temperature of 220 ° C. or higher, a paper-like material made of an organic binder, a nonwoven fabric, and the like. Alternatively, it includes a sheet-like material.

Here, the para-type aromatic polyamide short fiber is an aromatic homopolyamide represented by the following formula (I) in which at least 80 mol%, preferably at least 90 mol% of the repeating units constituting the polyamide are: Alternatively, it is a short fiber made of an aromatic copolyamide.

Here, Ar ₁ and Ar ₂ represent aromatic groups, and among them, the same or different aromatic groups selected from the following formula (II) are preferable. However, the hydrogen atom of the aromatic group may be substituted with a halogen atom, a lower alkyl group having 1 to 3 carbon atoms, a phenyl group, or the like.

[0015]

Embedded image

[0016]

Embedded image

Specifically, para-type wholly aromatic polyamide fibers such as polyparaphenylene terephthalamide fiber and copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide fiber are exemplified.

The production method and fiber properties of such wholly aromatic polyamide fibers are described in, for example, British Patent No. 150
No. 1948, U.S. Pat. No. 3,733,964, U.S. Pat. No. 3,767,756, U.S. Pat. No. 3,869,429, Japanese Patent Application Laid-Open Nos. 49-100322, 47
JP-A-10863, JP-A-58-144152, JP-A-4-65513, and the like.

The proportion of the para-aromatic polyamide short fibers in the total weight of the paper must be 50 to 95% by weight. If the ratio is outside the above range, the heat resistance and dimensional stability of the resulting aromatic polyamide fiber paper will be poor.

The above-mentioned para-type aromatic polyamide staple fiber is 5 to 5% based on the total weight of the aromatic polyamide staple fiber.
A short fiber consisting of 95% by weight of a homopolymer;
It is necessary to include by weight short fibers of the copolymer.

When the ratio of short fibers composed of a homopolymer to short fibers composed of a copolymer is out of the above range, it is difficult to achieve both dimensional stability and laser workability of the resulting aromatic polyamide fiber paper.

The thermoplastic resin short fibers having a softening temperature of 220 ° C. or higher are particularly soft fibers which are softened at 220 ° C. or higher and can bond the para-type aromatic polyamide short fibers with an organic binder described later. There is no limitation, but among them, meta-type aromatic polyamide short fibers are preferred. The ratio of the short thermoplastic fibers to the total weight of the paper is preferably 2 to 30% by weight. When the ratio is out of the above range, heat resistance and dimensional stability of the obtained aromatic polyamide fiber paper may be poor.

The meta-type aromatic polyamide staple fiber is a staple fiber composed of non-coaxial and non-parallel aromatic polyamide in which at least 50 mol% of the extended bonds are non-coaxial and non-parallel. As dicarboxylic acids, terephthalic acid,
A homopolymer or copolymer using one or more of isophthalic acid or the like and one or more of diamines such as metaphenylenediamine, 4,4-diaminophenyl ether, 4,4'-diaminodiphenylmethane, xylylenediamine, etc. Short fibers made of a polymerized polymer can be given.

Representative examples are polymetaphenylene isophthalamide, polymetaxylene terephthalamide,
Alternatively, it is a short fiber or the like made of a copolymer obtained by copolymerizing isophthalic acid chloride, terephthalic acid chloride, metaphenylenediamine and the like.
Aromatic polyamide short fibers in which 0 mol% or more is metaphenylene isophthalamide are preferred.

The single fiber fineness of the above-mentioned aromatic polyamide short fibers and thermoplastic resin short fibers having a softening temperature of 220 ° C. or higher is as follows:
Preferably, it is 0.3 to 5.0 denier. 0.3
If it is less than denier, 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 fluffing, but also the cost is high, which is not desirable. On the other hand, if it exceeds 5.0 denier, the mechanical properties of the fiber, particularly the strength, are greatly reduced, so that it is not practical. In addition, the aromatic polyamide short fibers may be partially fibrillated mechanically, but if the ratio is too large, the impregnating property of the compounded varnish is reduced and the object of the present invention is hindered. Therefore, it is desirable to reduce the ratio as much as possible.

The short fiber has a fiber length of 2 to 12 m.
m is preferable. If the fiber length is less than 2 mm, the resulting aromatic polyamide fiber paper (fiber aggregate) tends to have insufficient mechanical properties. On the other hand, if the fiber length exceeds 12 mm, the fiber opening properties and dispersibility of the short fibers are deteriorated, so that the uniformity of the obtained fiber aggregate is impaired, and the mechanical properties also tend to be insufficient.

As the binder component (binder) in the aromatic polyamide fiber paper used in the present invention, a water-dispersible organic resin binder is preferable, and examples thereof include an epoxy resin, a phenol resin, a melamine resin, and a fluororesin. Above all, a water-dispersible epoxy resin having an epoxy functional group in a molecule is optimal because it has good compatibility with the compounded varnish impregnated in the prepreg production process.

Another example of the binder component is a fibrid made of an organic polymer. Here, fibrid is a general term for thin leaf-like, scaly small pieces or fine short fibers that are randomly fibrillated, having fine fibrils exhibiting binder performance in a wet papermaking process. For example, Japanese Patent Publication No. 35-118
No. 51, JP-B-37-5732, etc., fibrids produced by mixing an organic polymer solution in a system in which a precipitant of the polymer solution and a shear force are present, As described in JP-B-59-603, a molded article having molecular orientation molded from a polymer solution exhibiting optical anisotropy is randomly fibrillated by applying a mechanical shearing force such as beating. An example is a fibrid that has been made, and the former is most suitable.

The proportion of the organic binder in the aromatic polyamide fiber paper should be 3 to 30% by weight, preferably 5 to 15% by weight. When the proportion of the binder is less than 3% by weight, for example, the bonding strength and adhesive strength between short fibers during papermaking are too small to exhibit sufficient tensile strength, and the prepreg impregnated with a subsequent calendering step or compounding varnish. It is not preferable because it is easy to cut in a manufacturing process or the like. On the other hand, when the content exceeds 30% by weight, impregnation of the compounded varnish is impaired to cause impregnation failure and impregnation unevenness,
Since the properties of the compounded varnish cannot be sufficiently exerted, it becomes unsuitable as a base material for a laminate for an electrically insulated circuit board, which is not preferable.

The above-mentioned aromatic polyamide fiber paper of the present invention may be produced by any conventionally known method. For example, an aromatic polyamide short fiber and a thermoplastic resin short fiber having a softening temperature of 220 ° C. or more are defined. Weighed so as to have a prescribed ratio, and the fiber concentration was about 0.15 to 0.40% by weight.
In the aqueous slurry prepared by uniformly dispersing and adjusting the slurry by adding it to water so that it becomes as necessary, after adding a dispersant and a viscosity modifier, if necessary, a wet papermaking method using a long-mesh or round-mesh paper machine. A wet paper is formed by applying an organic binder resin to the wet paper by a spray method or the like so as to have a weight of a predetermined solid content ratio, and then heating and pressing the dried paper obtained by drying. Thus, a desired aromatic polyamide fiber paper can be obtained.

Alternatively, after aromatic polyamide short fibers are randomly laminated on a belt while being opened with a high-speed fluid,
A desired amount of an organic polyamide resin paper can also be obtained by applying a required amount of an organic binder resin by a spray method, heating and pressing, and drying.

[0032]

The present invention will be described in more detail with reference to the following examples. In addition, the manufacturing method of the test piece used in the Example and the measuring method of physical properties are as follows.

<Method for Preparing Specimen> (1) Preparation of Prepreg High-purity brominated bisphenol A type epoxy resin and orthocresol novolak type epoxy resin were used as dicyandiamide as a curing agent and 2-ethyl- as a curing accelerator.
After impregnating an aromatic polyamide fiber paper with a compounded varnish obtained by dissolving an epoxy resin composition containing 4 methylimidazole in a mixed solution of methyl ethyl ketone and methyl cellosolve, for 5 to 10 minutes at 110 to 120 ° C After drying, a B-stage prepreg paper having a resin content of 55% by volume was produced.

(2) Preparation of Laminate for Electric Circuit Board Five prepregs were laminated, and copper foil having a thickness of 18 μm was laminated on both sides, pressure was 20 to 50 kg / cm ² , temperature was 170 to ²
The resin was cured by heating and pressing at 60 ° C. for 60 minutes to obtain a laminate for an electric circuit board, and further subjected to a post-curing treatment in a hot-air dryer at 230 ° C. for about 20 minutes.

(3) Preparation of Via for Laminated Body for Electric Circuit Board After etching and removing the surface copper foil of the laminated body for an electric circuit board, a via having a diameter of 200 μm was fabricated using a carbon dioxide laser.

<Measurement Methods of Physical Properties> (1) Tensile Strength of Paper It was measured by a method according to JIS C-2111-7 using a constant-speed elongation type tensile tester.

(2) Paper delamination strength Using a constant-speed elongation type tensile tester, length 200 mm, width 15
mm (mm)
/ 15 mm).

(3) Thermal dimensional change rate 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 300 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.

[0039]

(Equation 1)

(4) The amount of warpage of the laminate for an electric circuit board The laminate for an electric circuit board is cut, and 2 mm from the end of the laminate.
Leave the copper foil on both sides in a frame shape with a width of
The copper foil is removed by etching all portions corresponding to 0 mm square to prepare a sample for evaluation. The partially etched laminate for an electric circuit board was placed on a surface plate, and the lift amount at the point where the lift was greatest at the four corners of the laminate was measured.

(5) Accuracy of via of laminated body for electric circuit board The laminated board is cut so as to pass through the center of the via, and the inner diameter of the via is measured every 5 μm with an electron microscope, and the via accuracy is calculated by the following equation. Calculated. ○ If via accuracy is less than 5%, 5% or more 1
Less than 0% was rated as Δ, and 10% or more was rated as ×.

[0042]

(Equation 2)

[Examples 1 to 7] As para-type aromatic polyamide short fibers, single fiber fineness 1.5 denier, fiber length 3 m
m of a fiber comprising copolyparaphenylene / 3,4'-oxydiphenylene / terephthalamide (manufactured by Teijin Limited:
Technora) and single fiber fineness 1.4 denier, fiber length 3
mm of polyparaphenylene-terephthalamide (Kevlar 49 manufactured by DuPont), and as a thermoplastic short fiber having a softening temperature of 220 ° C. or more, polymetaphenylene having a single fiber fineness of 3.0 denier and a fiber length of 6 mm・
Using a fiber made of isophthalamide (manufactured by Teijin Limited: Conex), the mixture was mixed at the ratio shown in Table 1 and then disintegrated and dispersed in water with a pulper to obtain a dispersant having a concentration of 0.02%. (Matsumoto Yushi Co., Ltd .: YM-80)
Was added to prepare a papermaking slurry liquid having a fiber concentration of 0.15% by weight.

Next, using a tapping type square hand machine, papermaking is performed using the slurry for papermaking, and after dehydrating lightly under pressure, a water-dispersible epoxy resin binder having a solid concentration of 2% by weight (Dainippon Ink Co., Ltd.) Chemical Industry Co., Ltd .: Dick Fine EN-027
0) was applied by a spray method so that the resin content was as shown in Table 1, and then dried in a hot air dryer at 160 ° C. for about 20 minutes to obtain an aromatic polyamide fiber paper having a basis weight of 60 g / m ^2. I got Table 2 shows calendering conditions of the obtained aromatic polyamide fiber paper, and Table 3 shows physical properties of the aromatic polyamide fiber paper and a laminate for an electric circuit board produced therefrom.
Shown in

[Conventional Example 1] Single fiber fineness 1.5 denier,
A fiber made of copolyparaphenylene / 3,4′-oxydiphenylene / terephthalamide having a fiber length of 3 mm (manufactured by Teijin Ltd .: Technora) is disintegrated and dispersed in water by a pulper at a ratio shown in Table 1 and then dissolved in water. A dispersant (YM-80, manufactured by Matsumoto Yushi Co., Ltd.) was added to a concentration of 02% to prepare a papermaking slurry liquid having a fiber concentration of 0.15% by weight.

Next, using a tappy type square hand machine, papermaking is performed using the slurry for papermaking, and after light pressure dehydration, a water-dispersible epoxy resin binder having a solid concentration of 2% by weight (Dainippon Ink Co., Ltd.) Chemical Industry Co., Ltd .: Dick Fine EN-027
0) was applied by a spray method so that the resin content was as shown in Table 1, and then dried in a hot air dryer at 160 ° C. for about 20 minutes to obtain an aromatic polyamide fiber paper having a basis weight of 60 g / m ^2. I got Table 2 shows calendering conditions of the obtained aromatic polyamide fiber paper, and Table 3 shows physical properties of the aromatic polyamide fiber paper and a laminate for an electric circuit board produced therefrom.
Shown in

[Comparative Examples 1 to 4] In Example 1, the mixing ratio of para-type aromatic polyamide short fibers comprising a homopolymer and a copolymer and thermoplastic resin short fibers having a softening temperature of 220 ° C. or higher was changed as shown in Table 1. Except for this, the procedure was the same as in Example 1. Comparative Example 3 is an example in which a thermoplastic resin short fiber having a softening temperature of 220 ° C. or higher was not used, and Comparative Example 4 was an example in which an aromatic polyamide short fiber made of a copolymer was not used. The calendering conditions of the obtained aromatic polyamide fiber paper are shown in Table 2, and the physical properties of the aromatic polyamide fiber paper and the laminate for an electric circuit board produced therefrom are shown in Table 3.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Torukei Matsui 3-4-1, Amihara, Ibaraki-shi, Osaka Teijin Limited Osaka Research Center F-term (reference) 4F072 AA02 AB04 AB06 AB31 AD13 AD21 AD23 AG03 AH03 AH21 AJ04 AJ11 AJ36 AK05 AK14 AL12 4F100 AK01A AK47A BA01 DG01A DG10A DG18A DH01 DH02 EH07 EJ82A GB43 JB13A JG04 JJ03 JL03 JL04 4L055 AF35 AG69 AG79 AG80 AG87 AH37 EA04 EA13 EA13 EA13 FA19

Claims (8)

[Claims] 1. An aromatic polyamide fiber paper containing para-type aromatic polyamide short fibers, thermoplastic resin short fibers having a softening temperature of 220 ° C. or higher, and an organic binder as main components, occupying in the total weight of the paper. The amount of the para-type aromatic polyamide short fiber is 50 to 95% by weight, and the amount of the para-type aromatic polyamide short fiber is 5 to 95% by weight based on the total weight of the aromatic polyamide short fiber. Aromatic polyamide fiber paper comprising short fibers consisting of a polymer and short fibers consisting of 5 to 95% by weight of a copolymer. 2. The aromatic polyamide fiber paper according to claim 1, wherein the thermoplastic resin short fibers having a softening temperature of 220 ° C. or higher are meta-type aromatic polyamide fibers. 3. The aromatic polyamide fiber paper according to claim 1, wherein the para-type aromatic polyamide short fiber is a para-type aromatic polyamide short fiber having an equilibrium water content of 5.0% or more. 4. The aromatic resin according to claim 1, wherein the organic binder is at least one water-dispersible organic resin binder selected from the group consisting of an epoxy resin, a phenol resin, a melamine resin, and a fluororesin. Polyamide fiber paper. 5. The fiber length of a para-aromatic polyamide short fiber and a thermoplastic resin short fiber having a softening temperature of 220 ° C. or more is 2 to 5.
The aromatic polyamide fiber paper according to any one of claims 1 to 4, which is in a range of 12 mm. 6. The aromatic polyamide fiber paper has a bulk density of 0.
Aromatic polyamide fiber sheet as claimed in any one of claims 1 to 5 is 35~0.85g / cm ^3. 7. A prepreg formed by impregnating an aromatic polyamide fiber paper with a thermosetting resin, wherein the aromatic polyamide fiber paper is an aromatic polyamide fiber paper according to any one of claims 1 to 6. A prepreg characterized by being a polyamide fiber paper. 8. A laminate formed by heating and pressing an aromatic polyamide fiber paper impregnated with a thermosetting resin, wherein the aromatic polyamide fiber paper is any one of claims 1 to 4. 13. A laminated board characterized in that it is the aromatic polyamide fiber paper according to the above item.