JP2002317392A - Method of producing poly-para-phenylene terephthalamide paper and method of producing printed circuit substrate therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing poly-p-phenylene terephthalamide which can utilize the high heat resistance and high Young's modulus intrinsic to this fiber by reducing the Na content on the fiber surface to improve the electric properties and strength properties under the hygroscopic conditions and provide a method of producing printed circuit substrates. SOLUTION: A web for making paper comprising short-cut fibers including >=50 wt.% of poly-p-phenylene terephthalamide is impregnated with a binder and they are cured to make the objective poly-p-phenylene terephthalamide. In this case the poly-p-phenylene terephthalamide is washed with an acid to remove sodium sulfate (mirabilite).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyparaphenylene terephthalamide paper having a high Young's modulus, good dimensional stability, and excellent heat resistance. The present invention relates to a method for producing a polyparaphenylene terephthalamide paper having improved electrical and strength properties under moisture absorbing conditions by reducing the rate, and further relates to a method for producing a printed circuit board using the polyparaphenylene terephthalamide paper. It is.

[0002]

2. Description of the Related Art Conventionally, polyparaphenylene terephthalamide (hereinafter, abbreviated as PPTA) fiber has excellent strength, heat resistance and high Young's modulus, and is used for industrial,
It is used as a short fiber for special clothing.

The PPTA fiber is formed into a liquid crystal state by using concentrated sulfuric acid as a solvent for dissolving the polymer during spinning and then subjected to shearing by a die to form a yarn with a high degree of crystallinity. It is known that concentrated sulfuric acid as a solvent is washed with water and neutralized with an alkali immediately after spinning, dried and heat-treated at 200 ° C. or higher, and then wound up as a filament (US Pat. No. 3,767,756).

[0004] The fiber thus obtained is cut with a cutter or the like, or is processed so as to be fibrillated by applying mechanical shearing, so that chopped fiber of PPTA or fibrillated pulp-like short fiber can be obtained. can get. Then, application of such PPTA short fiber to aramid paper suitable as a base material of a printed circuit board has been attempted.

[0005] However, the short fiber obtained as described above has a salt formed by neutralization incorporated in the fiber, and usually becomes a short fiber containing 0.5 to 3% by weight of salt. I will. For example, when sodium hydroxide is used at the time of neutralization, the salt is Na ₂ SO ₄ , so-called sodium sulfate, and the main constituent ions are Na ⁺ and SO ₄ ^2- , and the molar ratio is about 2: It is one. Moreover, since the surface of the PPTA fiber is in a solidified state of the formed salt and the polymer at the time of neutralization, it cannot be easily removed in the washing step.
When short fibers are used under humid conditions, this salt is ionized by the presence of water, and when electrical insulation is required, it may be an obstacle to energization.

In order to reduce the amount of sodium sulfate contained in the PPTA fiber, JP-A-11-181622 has improved the crystal structure of the polyparaphenylene terephthalamide fiber. That is, the polyparaphenylene terephthalamide fiber is deionized in a state where the crystal size (110 planes) is 50 Å or less, the alkali content is 0.5% by weight or less, and the water content is 15 to 100% by weight. 0.2% by weight of alkali (Na ion)
(2000 ppm) or less, and the crystal size was increased to 50 Å or more by heat treatment. However, even with such improvements, 200 p
pm or more of Na ions remained, which was one of the causes of lowering the performance of electrical characteristics.

In addition, the above-mentioned PPTA fiber, a paper web mainly composed of aramid fiber such as polyparaphenylene phenyl ether terephthalamide fiber and polymetaphenylene sophthalamide fiber is used as a material utilizing heat resistance and dimensional stability. However, in order to obtain aramid paper from these fibers, a binder for strengthening the bond between the fibers is required. For example, Tokiko Sho 52
-39474 and JP-A-6-310823, that is, an epoxy resin is reacted with an aliphatic amine, and an acid is added to the reaction product in the middle to obtain a weakly acidic water-soluble or water-dispersible compound. It is conceivable to apply the obtained epoxy binder. However, the above-mentioned epoxy binder has caused a specific problem when used for PPTA. In other words, this type of resin becomes an excellent cured epoxy resin only after the neutralizing acid such as acetic acid volatilizes in the drying process, but the non-volatile epoxy resin reacts with the acid remaining on the surface or inside of the fiber of PPTA. , For example, a sodium acetate salt. When such a non-volatile salt is formed, the curing of the epoxy is insufficiently completed, and the hygroscopic acetate remains in the web, so that the electrical properties are significantly reduced. Further, since the acetic acid is concentrated and boiled in the drying process in the binder impregnated on the fiber surface, even Na fixed to the fiber in a solidified state is ionized and eluted.
In such a state, the curing of the binder is hindered and the strength is insufficiently exhibited, and further, for example, in the reaction with the epoxy resin of the printed wiring board, the curing is hindered to deteriorate the performance. Therefore, in the combination of the PPTA fiber and the binder, it is particularly necessary to completely remove Na.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to improve the electrical properties and strength properties under moisture absorbing conditions by reducing the Na content on the fiber surface in order to solve the above-mentioned drawbacks of the prior art. It is another object of the present invention to provide a method for producing polyparaphenylene terephthalamide paper and a method for producing a printed circuit board, which make it possible to effectively utilize the inherent high heat resistance and high Young's modulus of the fiber.

[0009]

According to the present invention, there is provided a method for producing a polyparaphenylene terephthalamide paper for achieving the above-mentioned object, comprising the steps of producing a paper web comprising short fibers containing 50% by weight or more of polyparaphenylene terephthalamide fibers. A method for producing polyparaphenylene terephthalamide paper by impregnating and curing a binder, wherein the polyparaphenylene terephthalamide fiber is subjected to a washing treatment with an acid, and sodium sulfate attached to the polyparaphenylene terephthalamide fiber, more specifically, the fiber It is characterized in that the free or solidified sodium sulfate is eluted and removed on the surface and inside the fiber.

In the present invention, it is preferable that the polyparaphenylene terephthalamide fiber is washed with an acid to convert the SO ₃ Na group of the polyparaphenylene terephthalamide fiber into an SO ₃ H group.

The polyparaphenylene terephthalamide fiber has a crystal size (110 planes) of 50 Å or less, an alkali content of 0.5% by weight or less, and a water content of 15 to 100% by weight. It is preferable that the alkali content is 0.2% by weight or less and the crystal size is increased to 50 Å or more by heat treatment.

The polyparaphenylene terephthalamide fiber has a thickness of not less than 0.5 denier and not more than 3 denier,
A chop fiber having a length of 1 mm or more and 25 mm or less, and at least one type of staple fiber selected from fibrillated pulp-like material, and the polyparaphenylene terephthalamide fiber is formed into an acid after forming the staple fiber. It is preferable to carry out a washing treatment.

Further, in the above-mentioned washing treatment with an acid, it is preferable that the polyparaphenylene terephthalamide fiber is washed with sulfuric acid of 0.1 N or more.

As a binder for reinforcing a papermaking web,
It is preferable to use a resin which is made water-soluble or water-dispersible by reacting an epoxy resin with an amine and neutralizing with a volatile acid. In the present invention, a remarkable effect can be obtained when a binder of the above type is combined with polyparaphenylene terephthalamide fiber.

On the other hand, a method of manufacturing a printed circuit board according to the present invention comprises the steps of: bonding at least one prepreg obtained by impregnating the polyparaphenylene terephthalamide paper obtained by the above-described manufacturing method with a thermosetting resin; The printed circuit board is integrally molded by laminating and heating and compressing.

The present invention thoroughly removes salts such as sodium sulfate and alkali (Na) ions at the time of PPTA fiber formation, and further reduces the SO ₃ H group generated when the PPTA polymer raw material is dissolved in concentrated sulfuric acid to NaOH. By changing the SO ₃ Na group into a SO ₃ H group again by neutralization such as neutralization, alkali (Na) ions can be reduced to a level at which there is almost no problem. The SO ₃ Na group, which has a significant effect on electrical characteristics, especially under moisture absorbing conditions, can be converted into an SO ₃ H group to form a binder for reinforcing a papermaking web or an epoxy for processing into a printed circuit board. Since it reacts with a thermosetting resin such as a resin, the adhesion between the fiber and the resin is improved, and the moisture absorption resistance, the interlayer strength of the laminate, the peel strength with the copper foil, and the like are improved.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION PPTA used in the present invention is a polymer obtained by polycondensation of terephthalic acid and paraphenylenediamine, but may be a copolymer obtained by copolymerizing a small amount of a dicarboxylic acid and a diamine. The molecular weight of these polymers or copolymers is usually preferably from 20,000 to 25,000.

The PPTA fiber is prepared by dissolving PPTA in concentrated sulfuric acid, extruding a viscous solution from a spinneret, spinning into air or water to form a filament, and neutralizing with an aqueous sodium hydroxide solution. , Eventually 12
It is obtained by drying and heat treatment at 0 to 500 ° C. Further, by controlling the alkali ion content to 1.0% or less, use in the electric and electronic fields becomes possible.

The water content of PPTA short fiber is 15-100.
It is preferably maintained at a weight percent. To achieve such a water content, the spun PPTA fiber is heated to 100 to 150 ° C.
For 5 to 20 seconds. If the drying temperature is lower than 100 ° C., it is difficult to remove water, and if the drying temperature is higher than 150 ° C., crystallization proceeds, and subsequent deionization tends to be impossible. The fiber thus obtained is cut by a cutter or the like so as to have an aspect ratio of 50 to 5000,
Alternatively, it is machined so as to be fibrillated to obtain a desired chopped fiber of PPTA or a short fiber composed of pulp. Typically, a material having a thickness of about 1.5 denier and cut to 3 to 10 mm is easy to apply.

Since Na is solidified and adhered to the surface of the thus obtained PPTA short fiber in the form of NaSO ₄ salt (Glauber's salt), it is used after an operation of removing the Na salt in advance. The conditions of the Na removal treatment may be acidic, and the acidic bath for the treatment is not particularly limited as long as it is an acid such as an inorganic acid such as sulfuric acid or hydrochloric acid, or an organic acid such as acetic acid, citric acid or lactic acid. Among them, sulfuric acid is preferred. The concentration of the acid depends on the temperature and the contact time, and should be appropriately selected. For example, in the case of sulfuric acid, it may be 0.1 normal or more. After the treatment, the fibers are thoroughly washed with ion-exchanged water and
Removal of acidic components such as a ions and sulfate ions. In particular, when used for a printed circuit laminate, it is necessary to sufficiently clean the cleaning liquid so that the conductivity of the cleaning liquid is 5 μS / cm or less in order to exhibit excellent electrical characteristics. P
The effect of the acid treatment can be obtained from the PTA short fiber in the form of chopped fiber cut to a length of 1 mm to 25 mm, or a fibrillated pulp having a fine fiber structure by machining.

In the present invention, the effect of the acid treatment is as follows.
At the same time, the conversion of the SO ₃ Na groups formed by partially sulfonating the PPTA fibers and further neutralization into SO ₃ H groups is also achieved. In particular, it is of great significance to convert SO ₃ Na groups, which greatly affect electrical properties under moisture absorbing conditions, into SO ₃ H groups. This H reacts with the epoxy binder as active hydrogen and further reacts with a thermosetting resin such as an epoxy resin when processed into a printed circuit board, so that the adhesion between the fiber and the resin is improved, and the moisture absorption property and the like are improved. In addition, the interlayer strength of the laminate, the peel strength with the copper foil, and the like are improved. Originally, the SO ₃ Na group is a functional group that hinders the uniformity of the polymer composition of the PPTA fiber, but is inversely activated by the reactive group on the fiber surface, and has a weak adhesive force with the matrix resin. It improves the weakness of PPTA fiber.

The PPT thus treated to remove Na salt
The Na content of the short fiber A is attributed to sodium sulfate and SO ₃
The total amount of the Na-based substances may be quantified as the total amount of Na in the fiber, but the X-ray photoelectron spectroscopy (ESC
Quantifying the Na content within 10 nm of the fiber surface by measuring in A) is also an effective means. In any case, Na
Is 0.05% by weight or less, more preferably 0.03% by weight
(300 ppm) or less. 0.03
If the content is more than 300% by weight, no significant improvement in quality will be obtained.

As a means for obtaining PPTA fiber, there is a method for facilitating demolding nitrate as disclosed in Japanese Patent Application Laid-Open No. 11-181622. That is, the PPTA fiber has a crystal size (110 planes) of 50 Å or less, an alkali content of 0.5% by weight or less, and a water content of 1% or less.
In the state of 5 to 100% by weight, wash thoroughly with ion-exchanged water, deionize the paper to reduce the alkali content to 0.2% by weight or less, and heat-treat the web after drying the web to reduce the crystal size to 50 Å or more. It is desirable to reduce the water absorption of itself. If the acid treatment of the present invention is applied to this deionization step, it becomes a particularly effective deionization method.

PPTA fiber which can effectively exhibit the effect of the above deionization treatment is, for example, Ketra manufactured by Dupont Toray.
vlar EG type, but Kevlar2
It can be obtained from a product group such as 9, 49, 149, and “Twaron” manufactured by Teijin Twaron Co., Ltd. having almost the same composition, but is not particularly limited.

The low Na PPTA fiber thus obtained is processed into a resin composite, a rubber composite, a spun yarn, a woven fabric using the spun yarn, and a knitted fabric. Aramid paper made of PPTA fiber has improved adhesion and other properties.
It has the excellent properties of A, has improved adhesiveness to epoxy resin, and has excellent insulation properties, and is therefore most suitable for electric and electronic parts.

In order to obtain aramid paper from PPTA fiber thus de-Na-treated, at least 50% of the total fiber is required.
If it is blended in an amount of at least% by weight, aramid fibers and aromatic polyester fibers, such as polyparaphenylene diphenyl ether terephthalamide fibers and polymetaphenylene sophthalamide fibers, as long as the properties are not essentially deteriorated, and other heat resistance Fiber blending is acceptable. However, 50
When the amount is less than the weight percentage, the thermal expansion characteristics of the PPTA fiber cannot be exhibited.

A general method for obtaining PPTA paper is as follows. The above-mentioned acid-treated and washed short fibers mainly composed of PPTA fibers are dispersed in ion-exchanged water to form a slurry.
In this case, it is also effective to increase the suspension stability of the slurry by blending a viscosity agent such as polyacrylic amide and polyethylene oxide in order to make the dispersion uniform and to improve the formation. Papermaking can be performed on inclined machines, long nets, short nets,
This is performed by a round net machine or the like, and after dehydration, the binder is impregnated. The impregnation method is performed by a spray method, a saturator method, a flow coater method, or the like, and the drying is desirably performed by a facility considering mold release properties.

The amount of the binder is selected depending on the purpose, but is usually 5% by weight or more and 30% by weight or less in the whole aramid paper. It is also convenient to increase the web strength of PPTA paper by blending 5-15% of thermoplastic heat-resistant fiber such as unstretched fiber of polymetaphenylene sophthalamide or pulp as a binder with PPTA fiber. The internal addition method and the external addition method for impregnation are appropriately applied alone or in combination. Subsequently, a desired apparent density, for example, 0.68 g / cm ³ , is obtained by a hot-pressure calender, followed by heat curing to obtain PPTA paper. The rice tsubo is selected according to the purpose of use, but is generally 50-72 g / m
Often selected from ^two .

As the binder used for the impregnation, there is a binder obtained by introducing a carboxyl group into a bisphenol A type epoxy resin having a molecular weight of 4,000 to 6,000 by graft polymerization of methacrylic acid and neutralizing with a dimethylethanolamine. However, there is a problem that the solvent resistance and the resistance during heating are weak because the reaction with a crosslinking agent such as trimethylolmelamine is not easy.

On the other hand, as disclosed in JP-B-52-39474 and JP-A-6-310823, an epoxy resin is reacted with an aliphatic amine, and an acid is added to the reaction product in the middle to form a weak acid. In the present invention, those which have been made water-soluble or water-dispersible can be suitably used. This resin can be used in an aqueous medium without an emulsifier, and since the curing is completed without the need for a particularly long curing time at the same time as drying, it can be applied to an online production process as a binder for a nonwoven fabric, It can also be used as an adhesive. In the case where the papermaking web impregnated with the binder is densified with a calender, stronger strength can be obtained by densifying the papermaking web with a hot calender in a thermoplastic stage that is not completely cured. Thereafter, if necessary, the curing may be completed by heating.

The above epoxy binder is obtained as follows. As the epoxy resin, a polyfunctional epoxy resin such as glycidyl ether of bisphenol A, phenol novolak, and cresol novolak is suitable. If the epoxy resin has two or more glycidyl groups in one molecule, one or two or more kinds of epoxy resins are used. , And is not particularly limited. As the curing agent, an amine compound selected from one or more of an aliphatic amine having an active hydrogen, an alicyclic amine, and an amine compound having an aromatic ring structure is preferable. It is desirable that these are reacted in such a manner that the epoxy equivalent and the active hydrogen equivalent of the amine are approximately 1: 1. However, the reaction is not particularly limited. Further, methyl ethyl ketone (M
It is also appropriate to add a water-soluble organic solvent such as EK). The reaction is carried out with heating and stirring, but is always carried out at a temperature of generally not more than 60 ° C. in a reaction vessel equipped with a cooling function so as not to cause a runaway reaction. And neutralization with a volatile acid such as aqueous formic acid to terminate the reaction. At this time, the pH may be adjusted to 6 or less and the resin concentration may be adjusted to 30% or less. When an organic solvent is contained, the solvent in the tank containing the neutralizing solution is depressurized to remove the solvent, but these are only examples.

The water-solubilized epoxy resin thus obtained has the role of neutralizing acetic acid to form a quaternary amine acetate to make it water-soluble and to stop it in a prepolymer state at the same time. When applied as a binder,
When heated to a boiling point of acetic acid of 118 ° C. or more after the impregnation, the acetic acid evaporates and cures at a stretch to exhibit excellent performance as an original epoxy resin.

However, when impregnating the above binder into the paper PPTA paper, if the deionization treatment is not completed,
Due to the presence of Na ions of Glauber's salt adhering to the PPTA fiber, or sulfonated Na intervening partially on the fiber surface,
Acetic acid and Na ion react with heating for drying and curing to form a non-volatile Na acetate salt.
% The phenomenon of not completely evaporating occurs. When such a phenomenon occurs, PPTA paper may be formed in a state in which the curing and crosslinking reaction does not sufficiently occur, and in addition, solid Na acetate which inhibits electric characteristics remains in the web.

As in the present invention, Na on the surface of PPTA fiber
By removing and reducing the ions, it is possible to obtain high-strength paper because it does not inhibit the curing of the epoxy binder, and it is possible to remove sodium sulfate and sodium acetate which are not preferable for electric materials and cause moisture absorption. This makes it possible to produce a laminate having a low moisture absorption rate, which leads to an improvement in the delamination strength of the laminate, an improvement in the moisture resistance and electrical resistance, or an improvement in the silver migration problem. It should be noted that a decrease in the moisture absorption rate of the laminate leads to an improvement in the delamination strength, as described in
No. 138381, PPTA
Heating at about 180 ° C. in the process of processing the paper into a laminate;
Heat in a reflow oven during component mounting as a printed circuit board causes the water in the PPTA paper to vaporize and expand, causing delamination, so reducing the moisture absorption is extremely effective in improving the delamination strength of the laminate It is.

[0035]

EXAMPLE PPTA paper was actually produced using PPTA fiber (Kevlar).

The PPTA fiber has a crystal size (110 faces)
Is 50 angstrom or less, the alkali content is 0.5 wt% or less, and the water content is 15 to 100 wt%. The size is 50 Å or more. From this PPTA fiber, chopped fibers of 1.5 d / 3 mm and fibrillated pulp (Fr. 290 cc, Fr. 55
0 cc).

Prior to the production of PPTA paper, a binder for reinforcing the papermaking web was prepared. That is, 237.5 g of a phenol novolak epoxy resin “YDPN638EK” manufactured by Toto Kasei Co., Ltd. (190 g as a resin solid content, 47.5 g of an organic solvent containing methyl ethyl ketone) as an epoxy resin in a closed container, and tetraethylenepentamine 1 activity as a curing agent. 27 g of hydrogen equivalent was added, and 100 g of methyl ethyl ketone was added as an organic solvent for viscosity dilution. The ratio of the methyl ethyl ketone solvent in the reaction solution was 41.2% by weight.
Met. This reaction solution was reacted for a predetermined time while stirring and heating the resin to 45 ° C. and cooling to keep the resin temperature constant.
While sampling occasionally to confirm solubility in 10% acetic acid, 25% of 10% acetic acid aqueous solution was
2 g was added for neutralization, and 232 g of ion-exchanged water was further added to obtain a transparent water-soluble stock solution having a resin solid content of 25%. The temperature of the neutralized reaction solution is maintained at 30 ° C.
The pressure was reduced to 0 mmHg, and methyl ethyl ketone was volatilized and distilled out of the system over 2 hours. Then, ion-exchanged water was added, and a clear or milky pH of 5.9 having a resin solid concentration of 20% was added.
To obtain a water-soluble liquid having a viscosity of 13 mPa · S at 25 ° C.

Here, the acid treatment conditions for PPTA short fibers are shown in Table 1, the Na content after washing the PPTA short fibers under each treatment condition is shown in Table 2, and the fiber composition of the papermaking web is shown in Table 3.
It was shown to. In addition, the physical property in an Example followed the following measuring method.

(1) Na content of fiber surface "ESCALAB" manufactured by VG Scientific, UK
Focusing (150-1000 μm) by using a curved single crystal on the surface of a sample placed in ultra-vacuum using “220iXL”
A soft X-ray is irradiated, and photoelectrons emitted from a surface of 10 nm (nanometer) or less are detected by an analyzer.

(2) Content of Na in the whole fiber About 0.5 g of a sample is collected in a platinum dish, dissolved in sulfuric acid, and ashed with a gas burner and an electric furnace. The obtained ash is decomposed by heating with sulfuric acid, nitric acid and hydrofluoric acid, and dissolved in diluted nitric acid to obtain a constant solution. The measurement of the Na content in the obtained constant solution is performed by atomic absorption spectrometry.

(3) Glass transition temperature (Tg) The dynamic viscoelasticity of PPTA paper was measured, and its tan δ was measured.
The Tg temperature is determined from This Tg temperature is an index of the degree of binder curing.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

Next, as shown in Table 4, a printed circuit board was manufactured according to the following steps 1 to 7 for Examples 1 to 4 and Comparative Examples 1 to 4 in which the fiber blending and acid treatment conditions were changed. , And examined its characteristics.

[Step 1. Preparation of paper-made web, hand-sheeting method] Polyacrylamide as a viscosity agent in ion-exchanged water /
A web obtained by dispersing the fiber composition of Table 4 at a ratio of 0.15 g / L in a solution obtained by dissolving 45 ppm of a sodium polyacrylate copolymer, forming a paper with a 25 cm square hand-making machine, and dehydrating with a filter paper, It was sandwiched between nets and dewatered with a mangle to obtain a papermaking wet web, which was further washed with ion-exchanged water.
The fiber weight of the wet web is 62.
It was 6g / m ^2.

[Step 2. Binder impregnation method] The above-mentioned papermaking wet web sandwiched between nets was spray-impregnated with the above-mentioned 10% concentration solution of the epoxy binder, and then squeezed with a mangle to homogenize.

[Step 3. Drying Method of Web] The above-mentioned binder-impregnated web is coated on a PTFE sheet at a surface temperature of 135 ° C.
Was dried using a cylinder dryer. This drying was performed so that 5% of water remained. The basis weight after drying is 72.
Since it was 0 g / m ² , the amount of the resin adhered to the F1 web and the F2 web was 14.4 g / m ² , which was 20% of the total resin.

[Step 4. Heat Calendering Method] Subsequently, a calender composed of a steel roll having a surface temperature of 200 ° C. and a cotton roll having a surface temperature of 90 ° C. has a substantial linear pressure of 20 ° C.
The web was passed twice at 0 kg / cm and at a processing speed of 4 m / min with a reversal operation. In the case of the fiber blend F1, the change in thickness before and after the calender was as follows.

F1-C1 276 μm → 111 μm F1-C2 257 μm → 104 μm F1-T1 228 μm → 106 μm F1-T2 227 μm → 101 μm [Step 5. Thermosetting Method of Binder] The calendered web was subsequently heat-treated at 160 ° C. for 30 minutes.

[Step 6. Production method of copper foil-clad laminate] 70 parts of the above-mentioned PPTA paper with a flame-retardant epoxy resin ("YL6090" manufactured by Yuka Shell Epoxy) and a novolak type phenol resin ("YHL12" manufactured by Yuka Shell Epoxy)
9 ") 30% MEK 60% containing curing catalyst amine
A prepreg was obtained by impregnation and drying with a varnish solution. The resin amount was 51%. One prepreg and roughened 18
50kg by placing vacuum copper foil of both sides
/ Cm ² while increasing the temperature to 180 ° C.
After holding for 0 minute, a copper foil-clad laminate as a printed circuit board was obtained.

[Step 7. Method for Measuring Interlayer Peeling Strength, Measuring Method for Water Absorption] The copper foil-clad laminate was cut into a width of 10 mm and the peeling strength between layers was measured. Similarly, the copper foil of a copper-clad laminate made by stacking six prepregs was removed by etching, and the water absorption after 4 hours of PCT under a boiling condition of 121 ° C. was measured.

[0053]

[Table 4]

As can be seen from Table 4, all of Examples 1 to 4 had extremely high delamination strength of the copper-clad laminate, and showed good results in terms of water absorption.

Next, it was examined how the washing treatment of PPTA fibers with an acid reduces the amount of ionic substances in the state of the fiber alone and in the state of a dry cured product obtained by impregnating and curing a papermaking web with a binder. However, kevlar chop fiber 1.5d / 3mm was used as PPTA fiber, and the binder prepared as described above was used as the binder. The dried and cured product was composed of 80% by weight of fiber and 20% by weight of binder.

Comparative Example 5: After PPTA fibers were washed with ion-exchanged water, the conductivity of the washing liquid was measured. After forming a papermaking web from the washed PPTA fiber and impregnating and curing the binder, the dried and cured product is inserted into ion-exchanged water and boiled for 1 hour to extract an ionic substance,
The conductivity of the extract was measured.

Example 5: PPTA fiber was immersed in 0.3N sulfuric acid at a liquid ratio of 10 times at room temperature for 12 hours, washed with ion-exchanged water, and the conductivity of the washing liquid was measured. A papermaking web is formed from the thus washed PPTA fiber, and after impregnating and curing the binder, the dried and cured product is inserted into ion-exchanged water and boiled for 1 hour to extract an ionic substance. The conductivity was measured.

Table 5 shows the results of the conductivity. Also,
After the binder alone was cured, the dried and cured product was inserted into ion-exchanged water and boiled for 1 hour to extract an ionic substance. The conductivity of the extract was measured. cm. In the extraction of the ionic substance, the sample amount was 5% by weight of the extract. The conductivity is a value measured at 25 ° C.

[0059]

[Table 5]

As can be seen from Table 5, the PPTA fiber was used as a binder for reinforcing the papermaking web by reacting an epoxy resin with an amine and neutralizing with a volatile acid to make the fiber water-soluble or water-dispersible. When a resin is used, the amount of the ionic substance in the state of the dried and cured product is significantly increased as compared with the state of the fiber alone. However, in Example 5, the amount of the ionic substance in the state of the dried and cured product was significantly reduced as compared with Comparative Example 5. In the use of a printed circuit board that requires a high degree of electrical insulation, the conductivity under the above measurement conditions is required to be 100 μS / cm or less.

[0061]

As described above, according to the present invention, when producing a polyparaphenylene terephthalamide paper by impregnating and curing a binder into a short fiber web made mainly of polyparaphenylene terephthalamide fiber, Since the paraphenylene terephthalamide fiber is washed with an acid to reduce the Na content on the fiber surface, it is possible to improve the electrical properties and strength properties under moisture absorbing conditions, thereby achieving the inherent high heat resistance and high fiber properties. Effective use of Young's modulus is possible.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Tsunoda 1-5-6 Nihonbashi, Chuo-ku, Tokyo, 10th Central Building Toray Dupont Co., Ltd. (72) Inventor Tsutomu Yamamoto 1-chome, Nihonbashi, Chuo-ku, Tokyo 5-6, 10th Central Building Toray Dupont Co., Ltd. (72) Inventor Kazuki Yamada 2-5 Minatomachi, Gamagori-shi, Aichi Takemoto Yushi Co., Ltd. F-term (reference) 4L055 AF35 AF44 AF46 AG87 AH37 BE10 BE11 EA04 FA13 FA18 FA19 FA30 GA01 GA02 GA50

Claims (7)

[Claims] 1. A method for producing a polyparaphenylene terephthalamide paper by impregnating and curing a binder on a papermaking web made of short fibers containing 50% by weight or more of polyparaphenylene terephthalamide fibers. Is washed with an acid to elute and remove the sodium sulfate adhering to the polyparaphenylene terephthalamide fiber, thereby producing a polyparaphenylene terephthalamide paper. 2. The polyparaphenylene terephthalamide fiber is washed with an acid to convert the SO ₃ Na group of the polyparaphenylene terephthalamide fiber into an SO ₃ H group. A method for producing polyparaphenylene terephthalamide paper according to the above. 3. The polyparaphenylene terephthalamide fiber has a crystal size (110 planes) of 50 Å or less and an alkali content of 0.5% by weight or less.
2. The method according to claim 1, wherein the alkali metal content is reduced to 0.2% by weight or less and the crystal size is increased to 50 Å or more by heat treatment when the water content is 15 to 100% by weight. Alternatively, the method for producing the polyparaphenylene terephthalamide paper according to claim 2. 4. The polyparaphenylene terephthalamide fiber has a thickness of not less than 0.5 denier and not more than 3 denier,
A chop fiber having a length of 1 mm or more and 25 mm or less, and at least one type of staple fiber selected from fibrillated pulp-like material, and the polyparaphenylene terephthalamide fiber is formed into an acid after forming the staple fiber. The method for producing polyparaphenylene terephthalamide paper according to any one of claims 1 to 3, wherein the paper is subjected to a washing treatment. 5. The production of polyparaphenylene terephthalamide paper according to claim 1, wherein the polyparaphenylene terephthalamide fiber is washed with sulfuric acid of 0.1 N or more. Method. 6. A water-soluble or water-dispersible resin obtained by reacting an epoxy resin with an amine and neutralizing the same with a volatile acid as a binder for reinforcing the papermaking web. A method for producing the polyparaphenylene terephthalamide paper according to claim 5. 7. At least one material obtained by impregnating a polyparaphenylene terephthalamide paper obtained by the production method according to claim 1 with a thermosetting resin.
A method for manufacturing a printed circuit board, comprising: laminating a plurality of prepregs and a copper foil, and compressing by heating to integrally form the printed circuit board.