JP3475234B2 - Aromatic polyamide fiber paper - Google Patents

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 which is excellent in heat resistance and electric insulation under high humidity and can be used particularly for producing a laminate for electric circuit boards. More specifically, it relates to an aromatic polyamide fiber paper mainly composed of aromatic polyamide short fibers and an organic resin binder.

[0002]

2. Description of the Related Art Heat resistance, heat resistance, dimensional stability, moisture resistance, dimensional stability, electrical insulation, and deformation resistance (twisting, warping, corrugation, etc. are unlikely to occur in base materials used for laminates for electric circuit boards. Characteristics, such as lightness, are required. Aromatic polyamide fiber paper is superior to paper base materials made of other materials in terms of heat resistance, electrical insulation, heat-resistant dimensional stability, and light weight. It is being used as a base material for products.

For example, polymetaphenylene isophthalamide short fibers (Conex; manufactured by Teijin Limited) and polymetaphenylene isophthalamide pulp (fibrid).
"Electrically insulating paper (Japanese Unexamined Patent Publication No. 2-236907 and Japanese Unexamined Patent Publication No. 2-106840)", polyparaphenylene terephthalamide short fibers (Kevlar; manufactured by DuPont), and copolyparaphenylene-3,4 '. -Oxydiphenylene terephthalamide short fiber (Technora;
Aromatic polyamide fiber paper consisting of Teijin Ltd. and an organic resin binder "Resin impregnated sheet (JP-A-1-92)
No. 233) and a method for producing an aromatic polyamide fiber paper (Japanese Patent Laid-Open No. 2-47392).

However, although the former fiber paper is excellent in heat resistance, when it is heat-treated at a high temperature of 250 ° C. or higher, it not only shrinks to cause a dimensional change, but also has a high equilibrium moisture content (water content) of the fiber. Since the content of the impure ions is large, the electrical insulating property is poor especially when it is kept under high humidity for a long period of time, so that it cannot be used for an electrical insulating substrate which requires high reliability. On the other hand, the latter fiber paper is excellent in terms of the equilibrium moisture content of fibers and the content of impure ions,
Since only the organic resin is used as the binder component, the binder component migrates to the front and back sides of the paper and becomes unevenly distributed in the manufacturing process of the fiber paper, and as a result, the amount of the binder component present in the middle layer of the paper becomes minute. However, there is a problem that the uniformity of the obtained fiber paper in the thickness direction is reduced and the reliability is deteriorated.

When such a fiber paper is used as a base material for a laminate for an electric circuit board, its manufacturing process, in particular, a prepreg step of impregnating and drying a compounding varnish such as an epoxy resin and a step of laminating and molding the prepreg product, etc. The dispersion of the impregnated amount (particularly in the thickness direction) of the compounded varnish and the adhered amount increases, or a part of the binder resin melts, causing a decrease in the adhesive strength between fibers and cutting of the paper substrate. In addition, since the short fibers easily move to each other, the uniformity of the fiber density distribution deteriorates, and there is a problem that the laminate for electric circuit boards after the solder reflow step, which is processed at a high temperature, is deformed. There was not desirable.

In order to solve such a problem, a meta-type aromatic polyamide fibrid is used instead of an organic resin as a binder component, and a para-type aromatic polyamide short fiber (for example, Kevlar; manufactured by DuPont Co., Ltd.) is used. A fiber paper “high density para-aramid paper (Japanese Patent Laid-Open No. 61-16”, which is combined with fibrillated para-aromatic polyamide microfibers (for example, Kevlar; manufactured by DuPont).
No. 0500) ”has been proposed. This fiber paper is
Although it has excellent properties such as heat resistance, heat-resistant dimensional stability, moisture-resistant dimensional stability, and deformation resistance (it is difficult to cause twisting, warping, waviness, etc.), the meta-type aromatic polyamide fibrid Due to the manufacturing method, there is a problem that the equilibrium moisture content and the content of impure ions are high, and due to the composition of the fiber paper, the fibrillated fine fibers fill the spaces between the para-type aromatic polyamide short fibers, and these are the fibrid. Therefore, when used as a base material for a laminate for an electric circuit board, impregnability of a compounding varnish such as an epoxy resin is lowered, and partial uneven impregnation or impregnation failure is likely to occur, In particular, there is a problem that the electrical insulation properties frequently occur under high humidity, and this improvement is strongly desired.

[0007]

DISCLOSURE OF THE INVENTION The present invention is excellent in heat resistance and electric insulation under high humidity, and is particularly suitable as a base material for laminates for electric circuit boards. Problems, especially deformations in the manufacturing process of electrical circuit board laminates (twisting, warping, waviness, etc.)
It is an object of the present invention to provide a novel aromatic polyamide fiber paper which solves the problems of generation and lack of electrical insulation under high humidity.

[0008]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that as aromatic polyamide short fibers constituting aromatic polyamide fiber paper, they are independent from each other in the length direction. When using a para-aramid staple fiber having at least two annular protrusions, and the maximum diameter of each annular protrusion is 1.1 times or more the average diameter of the small diameter portion connecting these annular protrusions, It was determined that the aromatic polyamide fiber paper of

Thus, according to the present invention, in an aromatic polyamide fiber paper containing aromatic polyamide short fibers and an organic resin binder as main components, the amount of the short fibers in the total weight of the paper is 70 to 70%. 96% by weight, the amount of the organic resin binder is 4 to 30% by weight, and the aromatic polyamide short fibers have at least two independent annular protrusions in their length direction. However, 30 para-aramid short fibers whose maximum diameter of each annular protrusion is 1.1 times or more of the average diameter of the small diameter portion connecting these annular protrusions is used.
An aromatic polyamide fiber paper is provided which is characterized by occupying at least wt%.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The aromatic polyamide fiber paper in the present invention includes a paper-like material, a nonwoven fabric, or a sheet-like material composed of aromatic polyamide short fibers and an organic resin binder.

The aromatic polyamide short fibers used in the present invention are represented by the following formula (Formula 1) in which 80 mol% or more, preferably 90 mol% or more of the repeating units constituting the polyamide are used.
Is a short fiber composed of an aromatic homopolyamide or 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 (Formula 2) are preferable. 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.

[0012]

[Chemical 1]

[0013]

[Chemical 2]

The method for producing such aromatic polyamide and the fiber characteristics are described in, for example, British Patent No. 1501948.
U.S. Pat. No. 3,733,964, and No. 3767.
No. 756, No. 3869429, Japanese Patent Laid-Open Nos. 49-100322 and 47-108.
63, JP-A-58-144152 and JP-A-4-65513.

The aromatic polyamide short fibers used in the present invention are preferably para-type aromatic polyamide fibers such as polyparaphenylene terephthalamide fibers and copolyparaphenylene.3,4'-oxydiphenylene terephthalamide fibers. . In the meta-type aromatic polyamide fiber,
In some cases, the heat resistance is insufficient and the desired performance may not be obtained.

Among them, copolyparaphenylene containing terephthalic acid as an acid component and paraphenylenediamine and 3,4'-oxydiphenylenediamine as an amine component.
A fiber made of a 3,4′-oxydiphenylene / terephthalamide polymer is preferable because it has excellent heat resistance and the like.
The copolymerization molar ratio of para-phenylenediamine and 3,4'-oxydiphenylenediamine is 1: 3 to 3: 1, preferably about 1: 1.

The above aromatic polyamide short fibers have at least two annular protrusions independent of each other in the length direction, and the maximum diameter of each annular protrusion is a small diameter connecting these annular protrusions. It is necessary to occupy 30% by weight or more of para-aramid short fibers whose average diameter is 1.1 times or more.

That is, in the above-mentioned aromatic polyamide fiber paper, it is very important that the aromatic polyamide short fibers are uniformly and strongly bonded to each other, and in order to increase the bonding force, at least two aromatic polyamide fiber fibers are used. It is effective to use para-aramid short fibers having annular protrusions and having the maximum diameter of each annular protrusion of 1.1 times or more the average diameter of the small diameter portion connecting these annular protrusions.

That is, compared with short fibers having a uniform thickness, short fibers having at least two annular protrusions described above significantly increase the pull-out resistance of the fibers in the paper, and therefore have a large reinforcing effect. improves.

Here, "the maximum diameter is 1.1 times or more of the average diameter of the small diameter portion connecting these annular protrusions" means the annular protrusions DS1, DS2, DS3 and D in FIG.
DL1 having a diameter of 1.1 times or more the average diameter of S4,
It means DL2 and DL3.

At this time, even if the annular protrusions are present, the maximum diameter is 1. The average diameter of the small diameter portions connecting the annular protrusions is 1.
If it is not more than 1 time, it is not included in the annular projection portion in the present invention.

The short fibers in the present invention may have two or more annular projections in the length direction thereof, and in particular, both ends of the fiber (see FIG. 2) or the vicinity thereof (see FIG. 3). )
It is preferable to have an annular protrusion on the fiber because the fiber pullout resistance is further increased and a good reinforcing effect can be obtained. Here, the vicinity of both ends means a portion in which the distance L1 from the end portion E is within 20% of the total length L of the short fibers in FIG. 3, and it is desirable that the annular protrusion portion DL exists in this portion.

Further, in the present invention, it is necessary that the short fibers having at least two annular protrusions as described above account for 30% by weight or more of the whole aromatic polyamide short fibers. If the amount of the short fibers is less than 30% by weight, a sufficient binding effect cannot be obtained.

The short fibers used in the present invention, which have at least two annular protrusions in the lengthwise direction as described above, are, for example, spinning and drawing conditions (for example, discharge amount during spinning, spinning tension, draw ratio, etc.). ) Is intermittently changed, or when cutting into short fibers, it can be easily manufactured by a method such as cutting while applying tension and using a snapback during cutting to form an annular protrusion. it can.

The single fiber fineness of the above aromatic polyamide short fibers is preferably 0.3 to 5.0 denier.
If it is less than 0.3 denier, there are many difficult points in the spinning technology,
Not only is it difficult to stably produce good quality fibers due to yarn breakage and fluff, but also the cost is high, which is not desirable. On the other hand, when it exceeds 5.0 denier, the mechanical properties of the fiber, particularly the strength decrease, become large, which is not practical. The aromatic polyamide short fibers may be partially fibrillated mechanically, but if the proportion becomes too large, impregnation of the compounded varnish will be impaired and the object of the present invention will be impaired. Therefore, it is desirable to reduce the ratio as much as possible.

The fiber length of the aromatic polyamide short fibers is 2 to
12 mm is optimal. If the fiber length is less than 2 mm, the mechanical properties of the resulting aromatic polyamide fiber paper (fiber assembly) are likely to be insufficient. On the other hand, the fiber length is 12 mm
If it exceeds the above range, the openability and dispersibility of the short fibers are deteriorated and the uniformity of the obtained fiber assembly is impaired, and the mechanical properties tend to be insufficient.

Further, short fibers made of other materials, for example, glass, polyetheretherketone, polyetherimide, polyphenylene sulfide, ceramics, etc. may be mixed within a range that does not impair the inherent properties of the aromatic polyamide short fibers. Good. In this case, the proportion of the aromatic polyamide short fibers in all the constituent fibers is 80% by weight or more, preferably 90% by weight or more.

As the binder component (binder) other than the fibers in the aromatic polyamide fiber paper used in the present invention, an organic resin, particularly a thermosetting organic resin such as an epoxy resin, a phenol resin, a polyurethane resin or melamine is used. Resin and the like are suitable. Among them, a water-dispersible epoxy resin having an epoxy functional group in the molecule has the best compatibility with the compounded varnish to be impregnated in the prepreg manufacturing process and is most suitable.

The proportion of such an organic resin binder in the aromatic polyamide fiber paper should be 4 to 30% by weight, preferably 6 to 15% by weight. If the proportion of the binder is less than 4% by weight, for example, the binding force and adhesive force between short fibers at the time of papermaking become too small and sufficient tensile strength cannot be expressed, and the subsequent calendering step and compounded varnish are impregnated. It is not preferable because it is easy to cut in the prepreg manufacturing process. On the other hand, if it exceeds 30% by weight, impregnation of the compounded varnish is impaired, resulting in impregnation failure and uneven impregnation.
Since the properties of the compounded varnish cannot be sufficiently exhibited, it becomes unsuitable as a base material for a laminate for an electrically insulating circuit board, which is not preferable.

The aromatic polyamide fiber paper of the present invention described above may be produced by any conventionally known method. For example, the aromatic polyamide short fibers are weighed so as to have a predetermined ratio, Fiber concentration is about 0.15-0.40
If necessary, add a dispersant and a viscosity modifier to an aqueous slurry that has been uniformly dispersed and adjusted by pouring it into water so that the weight% of the product becomes wet. A wet paper is formed by a papermaking method, and an organic binder resin is applied to the wet paper by a spray method or the like so as to have a predetermined solid content ratio, and then the dried paper obtained is dried by heating and pressing. As a result, a desired aromatic polyamide fiber paper can be obtained. Alternatively, the aromatic polyamide short fibers are randomly laminated on the belt while opening with a high-speed fluid, and then the required amount of organic binder resin is applied by a spray method, followed by heating, pressurizing, and drying to obtain the target aromatic compound. It is also possible to obtain polyamide fiber paper.

[0031]

EXAMPLES The present invention will be specifically described below with reference to examples. The method for producing the test piece used in the examples, and
The evaluation method is as follows.

<Method for producing test piece> • Method for producing aromatic polyamide short fibers: Aromatic polyamide fibers spun to an excessive fiber diameter (fineness: 0.3 de to 5.0 de) are sprinkled with water while being added, Bundling to a total fineness of about 100,000 de, and then using the guillotine cutter, the target length is 2 mm to 12 mm.
Ratio of the maximum diameter R of the cut portion in the length direction or the vicinity of the cut portion to the minimum diameter r of the short fiber central portion R /
An aromatic polyamide short fiber having an r of 1.05 or more was obtained. Aromatic polyamide short fibers having a ratio R / r of less than 1.05 were produced as follows. Aromatic polyamide fibers spun to an appropriate fiber diameter (fineness 0.3 de to 5.0 de) are aligned while making them water, and bundled to a total fineness of about 100,000 decelerating, and then high speed (5 m / mi).
n. By applying pressure from the portion to the cutter rotating in the above), the target length was cut to 2 mm to 12 mm.

Preparation of fiber paper Aromatic polyamide short fibers cut by the above method were dispersed in water and made into paper by a known paper making technique. The paper making is 1
After being dried at 10 ° C., the temperature was 200 ° C. to 350 ° C. with a calendering device having a pair of metal rolls;
200 kg / m, calendar speed; 4 m / min. Calendar processing was performed for the calendar item.

Preparation of prepreg (impregnation with resin varnish) The base material is impregnated with resin varnish. When the resin-impregnated varnish is a thermosetting resin, a resin component main agent, a curing agent, a catalyst, and the like are dissolved and mixed in a solvent, and the viscosity is appropriately adjusted to be used. As the impregnation method, the fiber varnish was continuously impregnated into the resin varnish and the solvent was dried to prepare a coating machine. The prepreg used in the production of the printed wiring board is obtained by impregnating the resin varnish and then drying.

Preparation of printed wiring board (lamination) After impregnation with the resin varnish, electrolytic copper foil having a thickness of 35 μm is laminated on both surfaces of the prepreg, and thermocompression bonding is performed at a pressure of 20 to 50 k.
It was carried out under conditions of g / cm ² and temperature of 170 to 260 ° C. for 60 minutes. At this time, the lamination temperature is changed according to the type of impregnated resin and the difference in curing temperature.

<Evaluation Method> For the printed wiring board manufactured as described above, the bulk density of fiber paper, tensile strength, delamination strength, thermal dimensional change rate, and amount of warp of printed wiring board were measured. It was The measuring method is as follows.

Aromatic polyamide short fibers Ratio of maximum diameter R to minimum diameter r X = R / r 100 pieces of the obtained aromatic polyamide short fibers were observed with an optical microscope, and each of the aromatic polyamide short fibers The maximum value Rn (n = 1 to 100) of the diameter and the minimum diameter rn (n = 1 to 100), and the ratio Xn (n =
1 to 100). The average of the obtained Xn is Xn.
(Av.). Xn (Av.) = (Xl + X2 + ... + X100) / 1
00

-Bulk density of paper It was measured according to 6.1 of JIS C-2111.

Tensile strength of paper Using a constant speed elongation type tensile tester, JIS C-2111 7
It was measured according to.

Delamination of paper Using a high-strength high-speed extension type tensile tester, length 200 mm, width 15
The strength at the time of peeling the middle layer portion of the 0 mm sample into a T shape was measured.

Thermal dimensional change rate of paper Using a high-precision two-dimensional coordinate measuring machine (Mutoh Kogyo Co., Ltd.), a sample having a length of 250 mm and a width of 50 mm is heat-treated before heat treatment and at 280 ° C. for 5 minutes. After that, the length was measured, and the thermal dimensional change rate was calculated by the following calculation formula. Thermal dimensional change rate [%] = {(| length after heat treatment−length before heat treatment |) / length before heat treatment} × 100

-Amount of warp of printed wiring board: The above-mentioned three prepregs are superposed, and the hardened board from which the copper foil of the double-sided copper-clad laminate of 200 mm square after hot pressing is removed is placed on the surface plate, and the four corners of the hardened board are placed. The area with the largest amount of floating was measured as the amount of warpage.

Example 1 As an aromatic polyamide fiber, a single fiber fineness of 1.5d consisting of copolyparaphenylene.3,4'-oxydiphenylene.terephthalamide.
e, an aromatic polyamide short fiber having a fiber length of 3 mm (Teijin Corp. Technora) 77% by weight (the ratio of the aromatic polyamide short fiber in the total weight is 83.7% by weight) and polymetaphenylene isophthalamide, Aromatic polyamide short fiber 1 with single fiber fineness of 3.0 de and fiber length of 6 mm
5% by weight (the ratio of aromatic polyamide short fibers to the total weight is 16.3% by weight) was used to make paper, and bisphenol A epichlorohydrin type water-dispersible epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc.) Dicfine EN-0270) water diluted solution (solid content concentration 2% by weight) was sprayed and then dried and hardened in a hot air dryer at 160 ° C. for about 20 minutes to give an aromatic polyamide short fiber amount of 92% by weight, An aromatic polyamide fiber paper containing 8% by weight of an epoxy resin binder was obtained.

However, as shown in the method for producing the test piece, among the aromatic polyamide short fibers, aromatic polyamide short fibers (copolyparaphenylene.3,4'-oxydiphenylene.terephthalamide) ( Teijin Ltd. Technora) 77% by weight (ratio of aromatic polyamide short fibers to the total weight of 83.7% by weight) is cut to R / r = 1.15 by a guillotine cutter and consists of polymetaphenylene isophthalamide 15% by weight of aromatic polyamide short fibers (the ratio of aromatic polyamide short fibers to the total weight is 16.3% by weight) has a speed of 8 m / min. Aromatic polyamide short fibers cut to R / r = 1.02 by a cutter rotating at 10 ° C. were used.

The constitution of the obtained fiber paper is shown in Table 1, and the results of evaluation of the paper property and the substrate property of this fiber paper according to the above measuring method are shown in Table 2.

[Example 2] As aromatic polyamide short fibers, the same copolyparaphenylene.3,4'-as in Example 1 was used.
The same procedure as in Example 1 was carried out except that 55% by weight of aromatic polyamide short fibers made of oxydiphenylene terephthalamide and 37% by weight of aromatic polyamide short fibers made of polymetaphenylene isophthalamide were used. A polyamide fiber paper was obtained. The constitution of this fiber paper is shown in Table 1, and various properties (paper properties, substrate properties) evaluated in the same manner as in Example 1 are as shown in Table 2.

[Example 3] As the aromatic polyamide short fibers, 77% by weight of aromatic polyamide short fibers (Kevlar 49, DuPont Co., Ltd.) having a single fiber fineness of 1.5 de and a fiber length of 3 mm made of polyparaphenylene terephthalamide were used. The procedure of Example 1 was repeated except that the aromatic polyamide fiber paper was obtained. The constitution of this fiber paper is shown in Table 1 and various characteristics (paper characteristics,
The substrate characteristics) were as shown in Table 2.

Example 4 As the aromatic polyamide short fiber, 77% by weight of aromatic polyamide short fiber (Dupont Kevlar 49) having a single fiber fineness of 1.42 de and a fiber length of 3 mm made of polyparaphenylene terephthalamide was used. The procedure of Example 1 was repeated except that the aromatic polyamide fiber paper was obtained. The constitution of this fiber paper is shown in Table 1 and various characteristics (paper characteristics,
The substrate characteristics) were as shown in Table 2.

Example 5 As aromatic polyamide short fibers, the same copolyparaphenylene.3,4'-as in Example 1 was used.
Short fibers from oxydiphenylene terephthalamide 80
% By weight and 15% by weight of aromatic polyamide short fibers made of polymetaphenylene isophthalamide, and the same procedure as in Example 1 was conducted except that the amount of the epoxy resin binder deposited was 5% by weight. A fiber paper was obtained. The composition of this fiber paper is shown in Table 1 and in Example 1.
Various properties (paper properties, substrate properties) evaluated by the same method as in Table 2 are shown in Table 2.

[Example 6] As aromatic polyamide short fibers, the same copolyparaphenylene.3,4'-as in Example 1 was used.
Short fibers from oxydiphenylene terephthalamide 72
Wt% and 13 wt% of aromatic polyamide short fibers made of polymetaphenylene isophthalamide are used, except that the amount of the epoxy resin binder attached is 15 wt%.
The same procedure as in Example 1 was carried out to obtain an aromatic polyamide fiber paper. The composition of this fiber paper is shown in Table 1 and in Example 1.
Various properties (paper properties, substrate properties) evaluated by the same method as in Table 2 are shown in Table 2.

[Example 7] As aromatic polyamide short fibers, the same copolyparaphenylene-3,4'-as in Example 1 was used.
Oxydiphenylene terephthalamide short fibers 64
Wt% and 11 wt% of aromatic polyamide short fibers made of polymetaphenylene isophthalamide, and except that the amount of the epoxy resin binder attached is 25 wt%.
The same procedure as in Example 1 was carried out to obtain an aromatic polyamide fiber paper. The composition of this fiber paper is shown in Table 1 and in Example 1.
Various properties (paper properties, substrate properties) evaluated by the same method as in Table 2 are shown in Table 2.

[Example 8] As aromatic polyamide short fibers, the same copolyparaphenylene.3,4'-as in Example 1 was used.
Example 1 except that an aromatic polyamide short fiber in which the fiber length of the short fiber made of oxydiphenylene terephthalamide was changed to 5 mm and the fiber length of the short fiber made of polymetaphenylene isophthalamide was changed to 10 mm was used.
The same procedure was followed to obtain an aromatic polyamide fiber paper. The constitution of this fiber paper is shown in Table 1, and various properties (paper properties, substrate properties) evaluated in the same manner as in Example 1 are as shown in Table 2.

Example 9 Copolyparaphenylene 3,
Example 1 except that aromatic polyamide short fibers made of 4'-oxydiphenylene terephthalamide (Teijin Co., Ltd. Technora) were cut with a guillotine cutter to R / r = 1.25. The same procedure was followed to obtain an aromatic polyamide fiber paper. The constitution of this fiber paper is shown in Table 1, and various properties (paper properties, substrate properties) evaluated in the same manner as in Example 1 are as shown in Table 2.

Example 10 Copolyparaphenylene
The single fiber fineness of the aromatic polyamide composed of 3,4'-oxydiphenylene terephthalamide was changed to 0.75 de, and aromatic polyamide short fibers cut to R / r = 1.12 by a guillotine cutter were used. Except for this, the same procedure as in Example 1 was carried out to obtain an aromatic polyamide fiber paper.

The constitution of this fiber paper is shown in Table 1 and
Various properties (paper properties, substrate properties) evaluated by the same method as in Example 1 are as shown in Table 2.

[0056]

[Table 1]

[0057]

[Table 2]

[Comparative Example 1] As an aromatic polyamide fiber, as in Example 1, copolyparaphenylene.3,4 '
-77% by weight of oxydiphenylene terephthalamide short fibers (the ratio of aromatic polyamide short fibers to the total weight is 79.4% by weight) and 20% of aromatic polyamide short fibers made of polymetaphenylene isophthalamide. % (The ratio of the aromatic polyamide short fibers in the total weight is 20.6% by weight) was used to obtain an aromatic polyamide fiber paper in the same manner as in Example 1. The configuration of this fiber paper is shown in Table 3, and various properties evaluated by the same method as in Example 1 (paper properties, substrate properties) are as shown in Table 4.

[Comparative Example 2] As aromatic polyamide fiber, as in Example 1, copolyparaphenylene.3,4 '
-55% short fibers made of oxydiphenylene terephthalamide (84.6% by weight of the total weight of aromatic polyamide short fibers) and 10% by weight aromatic polyamide short fibers made of polymetaphenylene isophthalamide.
(The ratio of aromatic polyamide short fibers to the total weight is 1
5.4% by weight) was used to obtain an aromatic polyamide fiber paper in the same manner as in Example 1. The configuration of this fiber paper is shown in Table 3, and various properties evaluated by the same method as in Example 1 (paper properties, substrate properties) are as shown in Table 4.

[Comparative Example 3] As an aromatic polyamide fiber, as in Example 1, copolyparaphenylene.3,4 '.
-25% of short fibers made of oxydiphenylene terephthalamide (27.2% by weight in the total weight of aromatic polyamide short fibers) and 67% by weight of aromatic polyamide short fibers made of polymetaphenylene isophthalamide.
(The ratio of aromatic polyamide short fibers to the total weight is 7
2.8% by weight) was used to obtain an aromatic polyamide fiber paper in the same manner as in Example 1. The configuration of this fiber paper is shown in Table 3, and various properties evaluated by the same method as in Example 1 (paper properties, substrate properties) are as shown in Table 4.

[Comparative Example 4] As aromatic polyamide fiber, as in Example 1, copolyparaphenylene.3,4 '
-Using copolyparaphenylene-3,4'-oxydiphenylene terephthalamide using 77% of short fibers of oxydiphenylene terephthalamide and 15% by weight of aromatic polyamide short fibers of polymetaphenylene isophthalamide. Aromatic polyamide short fiber made of R / r = 1.
Aromatic polyamide fiber paper was obtained in the same manner as in Example 1 except that it was cut into pieces. The configuration of this fiber paper is shown in Table 3, and various properties evaluated by the same method as in Example 1 (paper properties, substrate properties) are as shown in Table 4.

[Comparative Example 5] As aromatic polyamide fiber, as in Example 1, copolyparaphenylene.3,4 '
Example 1 except that 77% of short fibers made of oxydiphenylene terephthalamide cut to a fiber length of 6 mm and 15% of short fibers made of polymetaphenylene isophthalamide cut to a fiber length of 12 mm were used.
The same procedure was followed to obtain an aromatic polyamide fiber paper. Since the obtained fiber paper has a long fiber length, many fiber lumps were observed in the paper making process, and the fiber paper had large fiber density unevenness. The composition of this fiber paper is shown in Table 3 and in Example 1.
Various properties (paper properties, substrate properties) evaluated by the same method as in Table 4 are shown in Table 4.

[0063]

[Table 3]

[0064]

[Table 4]

[Brief description of drawings]

FIG. 1 is an enlarged side view for explaining the shape of reinforcing short fibers used in the present invention.

FIG. 2 is an enlarged side view showing an example of reinforcing short fibers used in the present invention.

FIG. 3 is an enlarged side view showing another example of the reinforcing short fibers used in the present invention.

[Explanation of symbols]

DL1, DL2, DL3, DL annular protrusion Ds1, DS2, DS3, DS4 small diameter part E Short fiber end Distance from L1 end to annular protrusion

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI H05K 1/03 610 H05K 1/03 610U (56) References JP-A-9-228289 (JP, A) JP-A-53-78319 (JP, A) JP 55-45885 (JP, A) JP 61-201099 (JP, A) JP 59-144609 (JP, A) JP 61-239099 (JP, A) Open 2001-295191 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D21H 11/00-27/42 D01F 1/00-13/04 H05K 1/03

Claims (3)

(57) [Claims] 1. In an aromatic polyamide fiber paper containing aromatic polyamide short fibers and an organic resin binder as main components, the amount of the short fibers in the total weight of the paper is 70 to 70.
96% by weight, the amount of the organic resin binder is 4 to 30% by weight, and the aromatic polyamide short fibers have at least two independent annular protrusions in their length direction. However, the maximum diameter of each annular protrusion is 1.1 times or more the average diameter of the small diameter portion connecting these annular protrusions, and the para-aramid short fibers occupy 30% by weight or more. Polyamide fiber paper. 2. The fiber length of the aromatic polyamide short fibers is 2 to
The aromatic polyamide fiber paper according to claim 1, which is 12 mm. 3. The aromatic polyamide fiber paper according to claim 1, wherein the single fiber fineness of the aromatic polyamide short fibers is 0.3 to 5.0 denier.