AU673691B2 - Water-containing aromatic polyamide pulp and process for producing the same - Google Patents

Abstract

A water-containing aromatic polyamide pulp which has been surface-treated with an epoxy resin and has a water-content of 30 to 95 % by weight. This pulp is produced by dispersing an aromatic polyamide pulp in an aqueous epoxy resin emulsion, filtering the mixture and then dehydrating the pulp separated.

Description

DPI DATE 29/03/94 APPLN. ID 49823/93 AOJP DATE 23/06/94 PCT NUMBER PCT/JP93/01237 AU9349823

(PCT)

(51) International Patent Classification 5 (11) International Publication Number: WO 94/05854 D21H !3/26, 17/52, D06NI 15/55 Al (43) International Publication Date: 17 March 1994 (17.03.94) (21) International Application Number: PCT/JP93/01237 (74) Agents- ASAMURA, Kiyoshi et al.; Room 33 1, New Ohternachi Bldg., 2-I, Ohternachi 2-chome, Chiyoda-ku, (22) International Filing Date: I September 1993 (01.09,93) Tokyo 100 (JP).

Priority data: (81) D~esignated States: AU, CA, KR, US, European patent 4/234428 2 September 1992 (02.09.92) JP (AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, LU, APkz' Z 0 ,1 -Z MC, NL, PT, SE).

(71) Applicant (for all designated States exrcept tJSp.-A444-N- [NL/NL]; Velperveg 76, NL-6824 BM Arnhem Published l{it/t international search report.

(72) Inventors; and Inventors/Applicants (far US only) :ASAGI, Kosaku [JP/ JP]; 4-5-68, Ninomniva, T-ukuba-shi, Ibaraki 305 (JP).

HATA, Shigenao [JP/JP), Parkside Tokiwadaira 302, 3-21-12, Tokiwadaira, Matsudo-shi, Chiba 270 (JP).

KOIZUMI, Tatsuya IJP/JP]; Sumitomo Kagaku Katsuragi-yo 301, 2-40-1, Kasuga, Tsukuba-shi, Ibaraki 305 (54)Title: WATER-CONTAINING AROMATIC POLYAMIDE PULP AND PROCESS FOR PRODUCING THE SAME (57) Abstract A water-containing aromatic polyamide pulp which has been surface-treated with an epoxy resin and has a water-content or 30 to 95 9b by weight. This pulp is produced by dispersing an aromatic polyamide ptulp in an aqueous epoxy resin emulsion, filtering the mixture and then dehydrating the pulp separated.

E350 31/4 -1

DESCRIPTION

WATER-CONTAINING AROMATIC POLYAMIDE PULP AND PROCESS FOR PRODUCING THE SAME 1 Technical Field anr This invention relates to ."stane g aromatic polyamide pulp surface-treated with an epoxy resin and to a process for producing the same. More S 5 particularly, it relates to a water-containing aromatic polyamide pulp which is suitable to uses requiring a step of dispersing aromatic polyamide pulp in water to make paper as in the production of wet type clutch facing, insulating paper and the like, and gives a product which can be easily handled and has excellent mechanical characteristics, and to a process for producing the same.

Background Art Aromatic polyamides such as poly(paraphenylene terephthalamide), poly(metaphenylene isophthalamide) and the like (referred to hereinafter as aramides in some cases) have been known to be useful for fiber, pulp, film and the like which are excellent in heat resistance, mechanical characteristics, electric characteristics and the like. In particular, aramid pulp obtained by fibrillating aramid+ fibers is useful as asbestos-substitutes.

AMIENDED SHET L-I-O~-C q 1 Processes for producing aramidi pulp have here-tofore been proposed. As an example, Japanese Pat.

Appln. Kokoku No. 59-603 discloses a process for producing aramidL pulp by forming a film-like material or a monofilament from an optically anisotropic dope of paraaromatic polyamide and then fibrillating the film-like material or monofilament by a mechanical shear force.

Japanese Pat. Appln. Kokai No. 2-200,809 discloses a process for producing aramidt pulp directly from a solution of a polymer of a meta-aromatic polyamide, and apparatus to be used therein.

When aramidt fibers are to be used as reinforcing fibers, it is important that the aramid i fibers are excellent in wettability and adhesiveness to a resin or rubber which is a matrix, and hence, various methods have been proposed for the purpose of improving the wettability and adhesiveness between aramid4 fiber and matrix.

Japanese Pat. Appln. Kokai No. 62-218,425, for example, discloses a method of improving the adhesiveness between an aramidi fiber and an epoxy resin by immersing or spray-coating an aramid4 material (short fiber, long fiber, woven fabric, sheet or the like) in or with an organic solvent solution of an epoxy resin and also subjecting the same to heat-treatment to apply the epoxy resin to the surface of the aramid± material.

In addition, Japanese Pat. Appln. Kokai No. 62-225,539 discloses a method of improving the adhesiveness of an P!DE: iE SHEET

L_

3 1 aramidj material to an epoxy resin by heat-treating the aramidi material in the presence of an ammonia gas before applying an epoxy resin to the aramidt material.

However, all these rethods are concerned with treatment of aramid4 fibers having a fiber diameter of about 12 m, and when these methods are applied to highly fibrillated aramidt pulp having a fiber diameter of 1 p.m or less the fibrils are adhered to one another to impair the dispersibility in water and fiberseparability of the aramidi pulp, so that it is difficult to apply the above methods as they are to the aramidl pulp.

Moreover, in the case of producing a wet type clutch facing and the like, aramidi pulp and other components such as inorganic filler are subjected to paper-making to prepare a composite paper; however, it is necessary in this case that fillers are uniformly dispersed in the paper. However, this is difficult because of a specific weight difference, and hence, it is intended to achieve the uniform dispersion by applying a dispersing aid or the like. However, at present, a satisfactory result is not always obtained, and the development of aramidf pulp having so good a filler retaining property as to make the uniform dispersion possible has been desired.

Disclosure of the Invention An object of this invention is to provide a AM8~O SHEET ~-1~1191 4 1 water-containing aramidi pulp which is applied to uses requiring a step of dispersing pulp in water to make paper as in the production of wet type clutch facing, insulating paper and the like and which is suitable for producing a product which is excellent in wettability and adhesiveness to a matrix and also in inorganic filler retaining property and exhibits high mechanical properties without impairing the dispersibility in water and fiber-separability of the aramid! pulp.

Another object of this invention is to provide a process for producing a water-containing aromatic polyamide which does not cause any environmental pollution problems resulting from waste water and the like in the treatment of aramidl pulp because the epoxy resin is 100% adsorbed on the pulp.

Other objects and advantages of this invention will become apparent from the following description.

According to this invention, there is provided a water-containing aromatic polyamide pulp which has been surface-treated with an epoxy resin and has a water content of 30 to 95% by weight.

This invention further provides a process for producing the above-mentioned water-containing aromatic polyamide pulp which comprises dispersing an aromatic polyamide pulp in an aquecus epoxy resin emulsion, filtering the resulting dispersion and dehydrating the pulp separated.

AmE1DEO .SKET i est Mode for CarryVing out the invention The aramidi used in this invention, that is, the wholly aromatic polyamide, is such that 85 mole or more o~f the amide bonds are obtained from an aromatic ring diamine and aromatic ring dicarboxylic acid components.

Specific examples thereof include poly(paraphenylene terephthalamide), poly(metaphenylene terephthalamide), polyparabenzamide, poly(4, 4'-diaminobenzanilide), poly(paraphenylene-2,6-na~hthalenedicarboxamide), co~oly(paraphenylene/4,4'-(3, 3'dimethyl-biphenylene) terephthalamide), copoly(paraphenylene/2, 5-pyridylene terephthalamide), poly(orthophenylene phthal-amide), poly(metaphenylene phthalamide), poly(parapheny-lene phthalamile), poly(orthopheny2lene isophthalamide), poly(metaphenylene isophthalamide), poly(paranhenylene isophthalamide), poly(orthophenylene terephthalamide), poly( naphthalene phthalamide), poly( 4,4' -dinhenviene orthophthalamide), poly(4,4'-dinhenylene isopohthalamide), poly(1,4-naphthalene phthalamide), poly(1, 4 naohthalene isophthalamide), poly( 1, isophthalanide) and the like; aromatic polyamides containing alicyclic amine, representatives of which are the above-mentioned aromatic diamtines whose benzene nucleus has been partially replaced with piperazine, 1, 5-dimethylpiperazine or 2, copolymers of aromatic polyamide containing two phenyl AMENDED SHEET 1 I -1L L--d I 6 1 groups in which the aromatic diamines are bonded through an ether linkage such as 3,3'-oxydiphenylenediamine, 3,4'-oxydiphenylenediamine or the like, or a group such as -SO 2 -NH- or the like, for example, poly(3,3'-oxydiphenylene tere-phthalamide)/poly(paraphenylene terephthalamide) copolymer, poly(3,4oxydipbhnylene terephthalamide)/poly(paraphenylene terephthalamide) copolymer; and the like.

The term "aramidi pulp" used herein means that having the form that aramidi fibers are highly fibrillated, whose specific surface area as measured by the BET method is preferably 3 to 25 m 2 and whose freeness as measured by the Canadian standard method in the "Pulp Freeness Test Method" of JIS P 8121 is preferably 100 to 700 ml, more preferably 150 to 700 ml.

The process for producing the aramidj pulp is not critical and such processes as mentioned above can be applied.

The epoxy resin for preparing the aqueous epoxy resin emulsion used in this invention may be any epoxy resin as far as it can achieve the purpose of this invention, and the following can be used: Bisphenol A type liquid epoxy resins such as Sumiepoxy ELA-128 (trade name of Sumitomo Chemical Co., Ltd.) and the like; bisphenol A type solid epoxy resins such as Sumiepoxy ELA-012 (trade name of Sumitomo Chemical Co., Ltd.) and the like; orthocresol novolak type epoxy resins such as Sumiepoxy ESCN-220L (trade

SS'E

WO 94/05854 PCT/JP93/01237 7 1 name of Sumitomo Chemical Co., Ltd.) and the like; triglyci-dylamine type epoxy resins such as Sumiepoxy ELM-120 (trade name of Sumitomo Chemical Co., Ltd.) and the like; tetraglycidylamine type epoxy resins such as Sumiepoxy ELM-434 (trade name of Sumitomo Chemical Co., Ltd.) and the like; etc.

Among them, the tetrafunctional tetraglycidylamine type epoxy resin is preferred in view of enhancing adhesiveness. Furthermore, the epoxy equivalent of the epoxy resin is preferably 1,000 g/eq. or less. When it exceeds 1,000 g/eq. a sufficient adhesiveness cannot be obtained.

The production of an aqueous emulsion using the above epoxy resin can be effected by a conventional method. That is, an aqueous epoxy resin emulsion is obtained by dispersing an epoxy resin in water by a high speed stirring in the presence of a nonionic surface active agent such as an ether compound of polyoxyethylene and a higher fatty acid alcohol.

In this case, the epoxy resin/surface active agent composition ratio by weight may be varied depending upon the kind of epoxy resin and the kind of surface active agent. However, in view of the stability and adhesiveness of emulsion, the composition ratio is preferably in the range of 97/3 to 70/30. It is also pciible to use commercially available epoxy emulsions which are those of epoxy resins such as ANS-1001, ANS- 1006 (trade names of Takemoto Yushi K. KP-756, KP- _I 1 1011 (trade names of Matsumoto Yushi K. and the like. In view of uniformity of treatment, the particle size of emulsion is preferably 15 4m or less, more preferably 5 u±m or less.

A water-containing aromatic polyamide pulp excellent in adhesiveness to a phenol resin or the like can be prepared by treating aramidi pulp with the above epoxy resin emulsion. In order to increase the amount of the epoxy resin adsorbed on the pulp in the treating solution, it is particularly preferable to hydrolyze a part of the glycidyl groups of the epoxy resin of the epoxy resin emulsion to convert the same to glycol groups, and no other particular means is required because the epoxy resin is 100% adsorbed on the aramid i pulp.

The emulsion of the epoxy resin, the glycidyl groups of which have been partially hydrolyzed to glycol groups, can be produced by a method of preparing an emulsion using as the starting material the hydrolysis product of an epoxy resin by a generally known method.

It is also possible to use a method comprising preparing an epoxy resin emulsion by a conventional method as discussed below and then hydrolyzing the resulting emulsion. According to the latter method, a uniform, stable emulsion can be obtained easily. In order to hydrolyze the emulsion, various methods can be used depending upon the kind of the emulsion and it is the As, simplest to subject the emulsion as such to heat- AMENDED SHEET WO 94/05854 PCr/JP93/01237 9 1 treatment. When the emulsion is allowed to stand at about room temperature for about 3-6 months it has been confirmed that hydrolysis proceeds considerably, from which it is understood that the effect of this invention is substantially obtained by such a method. As a result of hydrolysis, a part of the epoxy groups of the epoxy resin is split to a glycol group. The conversion of the hydrolysis is preferably 10% or more, more preferably or more and less than 90% of the initially existing epoxy groups.

When the hydrolysis is insufficient, the adsorption of the resin on the pulp tends to become insufficient, and when the hydrolysis is excessive, the performance of the treated pulp such as adhesiveness of the pulp to phenol resin or the like is reduced. In the hydrolysis, not only the formation of glycol groups but also increase of the molecular weight of the epoxy resin due to condensation are caused; however, as far as it does not adversely affect the stability of the emulsion it has no particular problem in this invention. The conversion of hydrolysis can be calculated from the following equation by measuring the epoxy equivalent: Conversion 100 x {1 -(WPEi/WPEx)} wherein WPEi is the initial epoxy equivalent and WPEx is the epoxy equivalent after the hydrolysis.

It has been found that by effecting the WO 94/05854 PCT/JP93/01237 10 i hydrolysis treatment, the zeta potential value which indicates the state of static electrification of epoxy resin particles in water is changed from strong negative value to strong positive value including polarity. The reason therefor is not necessarily clear; however, it is known that the zeta potential value of the aramide pulp shows a strong negative value, and hence, this electrical attraction is deemed to be a factor of the epoxy resin being substantially 100 adsorbed on the pulp in the process of this invention.

The suitable hydrolysis conditions may be varied depending upon the epoxy resin used, the kind of surface active agent used, the proportions and concentrations thereof and the like. As an example thereof, a nonionic emulsion [ANS-1006 (manufactured by Takemoto Yushi K. of Sumiepoxy ELM-434 (trade name of Sumitomo Chemical Co., Ltd.) which is a tetraglycidylamine type epoxy resin can be hydrolyzed in the following manner: The emulsion is heat-treated at 65 0 C for 130 hours to hydrolyze a part of the aiming glycidyl groups into glycol groups. By this treatment, the epoxy equivalent is increased from about 120 g/eq. to about 240 g/eq. In this case, the conversion of hydrolysis is about 50%. The zeta potential is changed from -20 mV to +15 mV. Also, as stated above, a similar effect can be obtained by allowing the epoxy resin emulsion to stand at room temperature for 3-6 months. Moreover, a catalyst such as an acid, an alkali, an amine or the ~lq~ 11 1 like can be used to promote the reaction.

The treatment of aramidj pulp with the abovementioned epoxy resin emulsion, the glycidyl groups of which have been partially hydrolyzed, is effected, for example, by the following method: First of all, the aramidj pulp is dispersed in water to the extent that a sufficient fluidity is obtained. The concentration of the aramid4 pulp dispersed in the dispersion is varied depending upon the specific surface area and the freeness of the pulp, and is preferably in the range of to 5% by weight. In order to uniformly disperse the pulp, a conventional propeller type stirrer can be used.

A pulper for pulp which is used for dispersing usual linter pulp is particularly effective for achieving the uniform dispersion.

Subsequently, with stirring the dispersion, the desired amount of the above-mentioned epoxy emulsion, the glycidyl groups of which have been partially hydrolyzed, is dropwise added. The amount of the emulsion added is such that the amount of the epoxy resin adhered is preferably 0.3 to 10% by weight, more preferably 0.5 to 10% by weight, most preferably 1 to 6% by weight, based on the weight of the dry pulp. When the amount of the epoxy resin adhered is less than 0.3% by weight, the desired mechanical properties are not obtained and a sufficient epoxy resin treating effect is not obtained. When it is more than 10% by weight, there is a tendency of the dispersibility of the pulp becoming AMENDED

SHEET

12 1 bad, and an effect corresponding to the amount of the resin adhered is nor obtained, so that it is inferior in economy.

After completion of the dropwise addition of the emulsion, the stirring as such is continued for 5 to minutes to adsorb the epoxy resin on the pulp surface. According to the process of this invention, the epoxy resin is substantially 100% adsorbed on the aramid pulp surface only by the above treatment.

The aramidj pulp treated with the epoxy resin emulsion can also be heat-treated. The treated pulp subjected to heat-treatment shows a tendency that the increase of freeness due to the emulsion treatment is smaller than that of the pulp on which the same amount of epoxy resin has been merely adsorbed at room temperature. This means that the dispersibility of pulp is not impaired by the heat-treatment, which is a particularly desirable feature.

After the adsorption of the emulsion, the dispersion is filtered in a conventional manner. When the pulp is treated with the epoxy emulsion, the glycidyl groups of which have been partially hydrolyzed, as in this invention, no epoxy resin is detected in the filtrate and the COD value of the filtrate can be controlled to a level of about 10 ppm.

Thereafter, dehydration is effected so that the desired water content is obtained to obtain a surface-treated, water-containing aramid puI,; The AMENDED SHEET 13 1 water content of the pulp is adjusted to 30 to 95% by weight.

The water content referred to above can be determined from the following equation: Water content {(W1 W2)/W1} x 100 wherein WI is the weight of the pulp in the hydrous state, and W2 is the weight of the pulp after drying.

In order to obtain a water content of less than 30%, a particular operation such as a great pressure, heat-drying or the like is required, and hence, this is not economical and, in addition, impairs the dispersibility of the treated pulp. When the water content is more than 95% by weight, the water-containing pulp becomes heavy, and hence, the operability becomes bad. Also, it is not economical in the aspect of transportation and the like. In uses such as wet type clutch facing, paper type gasket, insulating paper and the like which are prepared through the step of paper-making in water, the above-mentioned water content range is particularly preferable in view of easy handling, dispersibility and economy.

This invention is explained in more detail below referring to Examples, which are merely by way of illustration and not by way of limitation. In the Examples, the evaluation of water-containing aramidl pulp was conducted by the methods described below.

AMENDED

SHEET

_L 14 1 [Method of evaluating water-containing aramidj pulp] 1. Evaluation method 1 Evaluation using aramid" pulp/phenol resin impregnated paper Paper-making Water-containing pulp of a weight corresponding to 6.25 g of pulp in terms of absolute dry weight was weighed and dispersed in one liter of water at 3,000 rpm for 3 minutes in a 2-liter standard pulper (manufactured by Kumagai Riki Kogyo K. Subsequently, paper-making was conducted in a conventional manner using a 25-cm square shaped sheet machine (manufactured by Kumagai Riki Kogyo K. and a 80-mesh wire net, and thereafter dried at 120°C for 2 hours to obtain an aramid+ paper 25 cm square having an areal weight of 100 g/m 2 Impregnation with phenol resin Several sheets of a test piece having a size of 50 mm x 100 mm were cut from the above aramidi paper and weighed. Subsequently, a 22.5% methanol solution of a modified resole type phenol resin [PR-SCI-3 (trade name of Sumitomo Durez Co. Ltd.)] was prepared by dilution. The test pieces were uniformly impregn. ad with this solution so that the pulp/resin weight ratio became 44.5/56.5, and then, dried at 50 0 C for 20 minutes to prepare an impregnated prepreg.

Press-molding

AEES

1-61 AMENDED SHEET 15 1 Two sheets of the above prepreg were put one on the other, a spacer of 0.6 mm in thickness was placed and the resulting assembly was press-molded at 180 0 C and 6 kg/cm 2 for 10 minutes and then treated at 180 0 C for 2 hours in an oven to post-cure the resin.

Tensile test The impregnated paper obtained by the abovementioned method was measured for tensile strength :-der the following conditions: Test piece size: 10 mm x 100 mm Gauge length: 50 mm Crosshead speed: 5 mm/min 2. Evaluation method 2 Evaluation using aramid4 pulp/inorganic filler/ phenol resin clutch facing model molded article Paper-making Water-containing pulp of a weight corresponding to 6.25 g of pulp in terms of absolute dry weight and 4.2 g to 8.0 g of diatomaceous earth (controlled so that the pulp/diatomaceous earth weight ratio after paper-making became 6/4 depending upon the filler retaining property of pulp) were weighed, and then dispersed in one liter of water at 3,000 rpm for 3 minutes in a 2-liter standard pulper (manufactured by Kumagai Riki Kogyo K. Subsequently, the dispersion was subjected to paper-making in a conventional manner in a square shaped sheet machine 25 cm square (manufactured by Kumagai Riki Kogyo K. using a I L I I 16 1 wire net, and thereafter dried at 120 0 C for 2 hours to obtain a 25-cm square aramidj/diatomaceous earth composite paper (aramidi/diatomaceous earth weight ratio: about 60/40) having an areal weight of about 167 g/cm 2 Diatomaceous earth (filler)-retention The diatomaceous earth-retention of the treated pulp was determined from the following equation: Diatomaceous earth retention {(W3 W1)/W2} x 100 wherein W1 Absolute dry weight of pulp (including the amount of treating agent adhered) W2 Weight of diatomaceous earth charged W3 Dry weight of aramid±/diatomaceous earth composite paper Impregnation with phenol resin Several sheets of a sample of a size of 50 mm x 100 mm were cut from the above aramidi paper and weighed. Subsequently, a 11.25% methanol solution of a modified resole type phenol resin [PR-SCI-3 (trade name of Sumitomo Durez Co., Ltd.)] was prepared by dilution.

The above paper sample sheets were uniformly impregnated with this resin solution so that the pulp/diatomaceous earth/resin weight ratio became 60/40/35, and then dried at 50 0 C for 20 minutes to prepare an impregnated prepreg.

Press-molding AMENDED SHEET r LI L __II 17 1 Two sheets of the above prepreg were put one on the other, a spacer of 0.6 mm in thickness was placed and the resulting assembly was press-molded at 180 0 C and 6 kg/cm 2 for 10 minutes, and thereafter treated in an oven at 180'C for 2 hours to post-cure the resin, thereby obtaining a clutch facing model molded article having a porosity of Tensile test The tensile strength of the molded article obtained by the above method was measured under the following conditions: Test piece size: 10 mm x 100 mm Gauge length: 50 mm Crosshead speed: 5 mm/min 3. Evaluation method 3 (measurement of freeness) The freeness of water-containing aramidi pulp was measured according to the Canadian standard method in the "Pulp Freeness Test Method" of JIS P 8121.

4. Evaluation method 4 (Measurement of epoxy resin content) The epoxy resin content (amount of resin adhered) of the water-containing aramide pulp was determined by calculation from the weight of the dry pulp obtained by extracting the epoxy resin adhered to pulp with dichloromethane by a Soxhlet extractor, and the weight of the extract.

1- 4, S' '18 1 Example 1 At 80 0 C, 15 g of Sumiepoxy ELM-434 (trade name of Sumitomo Chemical Co., Ltd.), 1.5 g of Leodol SP-010 (trade name of Kao K. K. for a nonionic surface active agent) and 3.5 g of Leodol TW-L120 (trade name of Kao K.

K. for a nonionic surface active agent) were stirred for minutes to obtain a mixture. This mixture was cooled to room temperature, and then 80 cc of deionized water was dropwise added in one minute while the mixture was stirred at a high speed by a homogenizer, after which the stirring was continued for 3 minutes to obtain a stable epoxy resin emulsion. The particle size of the emulsion as measured by an optical microscope was 1 to pm.

In one liter of deionized water was dispersed g of poly(paraphenylene terephthalamide) pulp Ak.z obe /VI [T waron 1097 (trade name of Nippen- Aamide e-ge Ka-ei); speci-fic surface area by the BET method: m2/g; water content: 6% by weight] in a flask. To the resulting dispersion was dropwise added 6.7 g of the above emulsion while the dispersion was stirred, and thereafter, the stirring was continued at room temperature for 30 minutes. Subsequently, the dispersion was filtered and the pulp separated was dehydrated so that the water content became about 70% by weight to obtain a water-containing aramidt pulp which had been surfacetreated with an epoxy resin. The performance of this water-containing aramidj pulp was evaluated by the AMENDED SHEET 19 1 above-mentioned methods to obtain the results shown in Table 1. The dispersibility in water and fiberseparability of the water-containing aramidi pulp were good.

Example 2 The same procedure as in Example 1 was repeated, except that 4 g of Emulgen B-66 (trade name of Kao K. K. for a nonionic surface active agent) and 1 g of Kota-min B86P (trade name of Kao K. K. for a cationic surface active agent) were substituted for the surface active agent, to obtain an emulsion having a particle size of 0.5 to 3 p m. Furthermore, in the same manner as in Example 1, a water-containing pulp which had been surface-treated with an epoxy resin was obtained. This was evaluated in the same manner as in Example 1 to obtain the results shown in Table 1. The dispersibility in water and fiber-separability of the water-containing aramide pulp were good.

Example 3 The same procedure as in Example 1 was repeated, except that 5 g of Emulgen B-66 (trade name of Kao K. K. for a nonionic surface active agent) was substituted for the surface active agent, to obtain an emulsion having a particle size of 0.5 to 1 p m. Moreover, a water-containing aramide pulp which had been surface-treated with an epoxy resin was obtained in the AMENDED

SHEET

20 1 same manner as in Example 1. This was evaluated in the same manner as in Example 1 to obtain the results shown in Table 1. The dispersibility in water and fiberseparability of the water-containing aramidj pulp were good.

Example 4 In one liter of deionized water was dispersed g of Tjwaron 1097 in a flask. While the dispersion was stirred, 5.56 g of an epi-bis type epoxy emulsion [KP-756 (trade name of Matsumoto Yushi K. was dropwise added to the dispersion in one minute, after which the stirring was continued at room temperature for minutes. Subsequently, the resulting mixture was filtered and the pulp separated was then dehydrated until the water content became about 70% by weight to obtain a water-containing aramid pulp which had been surface-treated with an epoxy resin. This pulp was evaluated in the same manner as in Example 1 to obtain the results shown in Table 1. The dispersibility in water and fiber-separability of the water-containing pulp were good.

Example In one liter of deionized water was dispersed of Tiwaron 1097 in a flask, and with stirring this dispersion, 76.25 g of a polyglycidyl type epoxy emulsion [ANS-1006 (trade name of Takemoto Yushi K. K.) AMENDED SHEET "IIIL~bll- 9_ 21 1 allowed to stand for 6 months at room temperature; epoxy equivalent: 271 g/eq.; conversion: 68%; zeta potential: mV)] was dropwise added to the dispersion in one minute, after which the stirring was continued at room temperature for 30 minutes. Subsequently, the resulting mixture was filtered, and the pulp separated was then dehydrated until the water content became about 70% by weight to obtain a water-containing aramidj pulp which had been surface-treated with an epoxy resin. The performance of this pulp was evaluated in the abovementioned evaluation method to obtain the results shown in Table 1. The dispersibility in water and fiberseparability of the water-containing aramid± pulp were good.

Example 6 In one liter of deionized water was dispersed g of Tjwaron 1097 in a flask, and with stirring this dispersion, 6.25 g of a polyglycidyl type epoxy emulsion [ANS-1006 (trade name of Takemoto Yushi K. was dropwise added to the dispersion in one minute, after which the stirring was continued at room temperature for minutes. Thereafter, the temperature of the solution was elevated to 95 0 C and the stirring was continued for a further 2 hours. Subsequently, the resulting mixture was filtered and the pulp separated was then dehydrated until the water-content became about 70% by weight, to obtain a water-containing aramide pulp which had been AMENDED S1-EET -a LLILBL~ 22 1 surface-treated with an epoxy resin. The performance of this pulp was evaluated by the above-mentioned evaluation method to obtain the results shown in Table 1.

The dispersibility in water and fiber-separability of this water-containing aramidj pulp were good.

Example 7 In one liter of deionized water was dispersed g of T waron D1099 [trade name of .ip.p4 Aramide /20' :r ig~n-Kinh Q for poly(paraphenylene terephthalamide) pulp; specific surface area by the BET methjd: 16 m 2 /g; water content: 6% by weight] in a flask. With stirring this dispersion, 6.25 g of a polyglycidyl type epoxy emulsion (ANS-1006 (trade name of Takemoto Yushi K. allowed to stand at room temperature for 6 months; epoxy equivalent: 371 g/eq.; conversion: 68%; zeta potential: mV] was dropwise added to the dispersion in one minute, and the stirring was continued at room temperature for 30 minutes. Subsequently, the resulting mixture was filtered and the pulp separated was then dehydrated until the water content became about 70% to obtain a water-containing aramide pulp which had been surface-treated with an epoxy resin. This pulp was evaluated by the above-mentioned evaluation method to obtain the results shown in Table 1. The dispersibility in-water and fiber-separability of this water-containing aramide pulp were good.

SL AMENDED SHEET l:2r F 1 23 1 Examole 8 In a flask, 12 g of Tlwaron 1097 and 8 g of Tjwaron D1099 were dispersed in one liter of deionized water. In the same manner as in Example 7, a watercontaining aramide pulp which had been surface-treated with an epoxy resin was obtained. Evaluation was effected in the same manner as in Example 7 to obtain the results shown in Table 1. The dispersibility in water and fiber-separability of this water-containing aramide pulp were good.

Comparative Example 1 T waron 1097 (water content: about 6% by weight) was used without being subjected to treatment with an epoxy resin emulsion and evaluated by the abovementioned evaluation method to obtain the results shown in Table 1.

Comparative Example 2 T waron D1099 was used without being subjected to treatment with an epoxy resin emulsion and evaluated by the above-mentioned evaluation method to obtain the results shown in Table 1.

Comparative Example 3 A mixed pulp of 60 parts by weight of Tkwaron 1097 which had not been subjected to treatment with an epoxy resin emulsion and 40 parts by weight of T waron AMENDED SHEET brllP ra IPI__C__ NVO 914/05854 PCT/J P93/01237 24 1 D1099 which had not been subjected to treatment with an epoxy resin emulsion was used and evaluated by the above-mentioned evaluation method to obtain the results shown in Table 1.

Table 1 Tensile Tensile Freeness strength of strength of phenol- clutch impregnated facing model paper molded (kg/mm 2 article (kg/mm 2 (ml) Example 1 9.0 Example 2 8.9__ Example 3 8.5 Example 4 9.2 2.9 630 Example 5 9.7 2.7 675 Comp. Ex. 1 6.5 2.1 625 Example 6 8.8 2.8 645 Example 7 4.5 175 Comp. Ex. 2 6.1 2.9 325 Example 8 3.9 315 Comp. Ex. 3 2.5 500 I 1 Example 9 In an oven, 2 kg of a polyglycidyl type epoxy emulsion [ANS-1006 (trade name of Takemoto Yushi K. was allowed to stand at 65 0 C for 130 hours to heat-treat the emulsion. The epoxy equivalent of the epoxy emulsion as measured by the hydrochloric acid-dioxane titration method was increased from 123 g/eq. to 238 g/eq. by this treatment. Therefore, the conversion of hydrolysis was 48%. Also, the zeta potential of the emulsion particles as measured by an ELS-800 electrophoretic light-scattering photometer was changed from mV to +15 mV. No change in appearance such as settlement of particles or the like was found.

Example In one liter of deionized water was dispersed g of T waron D1099 [trade name of NTppn =mie- Yge4n-4ai&sha for a poly(paraphenylene terephthalamide) pulp; specific surface area by the BET method: 16 m2/g; water content: 6% by weight] in a flask. With stirring this dispersion, 3.125 g of the epoxy emulsion prepared in the same manner as in Example 9 was dropwise added to the dispersion in 30 seconds, and the stirring was continued at room temperature for 30 minutes. Subsequently, the resulting mixture was filtered and the pulp separated was then dehydrated until the water content became about 70% by weight to obtain a water-containing aramid pulp which had been surface-treated with an AMENDED

SHEET

II I- I I 26 epoxy resin, the glycidyl group of which had been partially hydrolyzed. The performance of the watercontaining aramidj pulp was evaluated by the abovementioned evaluation method to obtain the results shown in Table 2. The dispersibility in water and fiberseparability of the water-containing aramida pulp were good.

Example 11 In 150 liters of deionized water was dispersed 1.4 kg of Tiwaron D1099 in a 200-liter reactor. With stirring this dispersion, 440 g of an epoxy emulsion prepared in the same manner as in Example 9 was dropwise added to the dispersion in two minutes, and the stirring was continued at room temberature for 30 minutes. Subseqcently, the resulting mixture was filtered and the pulp separated was then dehydrated until the water content became about 70% by weight to obtain a watercontaining aramid pulp which had been surface-treated with an epoxy resin, the glycidyl groups of which had been partially hydrolyzed. The performance of the pulp was evaluated by the above-mentioned method to obtain the results shown in Table 2. The dispersibility in water and fiber-separability of the water-containing pulp were good. Also, the amount of the epoxy resin in the filtrate after filtration was measured by the GPC analysis using a 254 nm ultraviolet ray detector in a 150-C type GPC analyzer manufactured by Waters in which AMENDED SHEET LI~LIIIIIOI III~ -LL L Il-~ _I 27 1 the separating columns were Shodex KF 803, KF 802 and KF 801 (in series, each has a diameter of 8 mm and a length of 300 mm) manufactured by Showa Denko K. however, no epoxy resin was detected in the filtrate. Moreover, according to the 100°C potassium permanganate method described in JIS K 0102.17, the COD of the filtrate after the dehydration was measured to obtain a value of mg/liter.

Example 12 In one liter of deionized water was dispersed g of Thwaron D1099 in a flask, and with stirring this dispersion, 3.125 g of an epoxy emulsion (ANS-1006; conversion: substantially was dropwi'e added thereto in 30 seconds, after which the resulting mixture was stirred at room temperature for 30 minutes. Subsequently, the mixture was filtered and the pulp separated was then dehydrated until the water content became about by weight to obtain a water-containing aramidl pulp which had been surface-treated with an epoxy resin.

The performance of this pulp was evaluated by the abovementioned evaluation method to obtain the results shown in Table 2. Moreover, in the same manner as in Example 11, the epoxy resin content and COD in the filtrate after the above filtration were measured to obtain values of 53 ppm and 110 mg/liter, respectively.

AMENPED SHEET AMtD SNEET CIL-I _I~~L1 p ll~rLI 2'8 1 Comparative Example 4 An aramidi pulp (Twaron D1099; water content: about 6% by weight) which have not been subjected to any surface treatment was used as such in place of the surface-treated water-containing aramide pulp and evaluated by the above-mentioned evaluation method to obtain the results shown in Table 2.

Table 2 Example Example Example Comp. Ex.

11 12 4 Pulp 190 190 415 325 free'ess (ml) Amount of 5.0 5.0 treating agent adhered (wt. Epoxy Not 53 content detected of filtrate (ppm) COD of 10 110 filtrate (mg/l.) Diatoma- 90 85 80 ceous earthretention Tensile 4.0 3.8 3.3 strength of impregnated paper (kg/mm 2 /TR 0 II~ h MzgoE SHEEg I-e

Claims (8)

1. An aromatic polyamide pulp which has been surface-treated with an epoxy resin, wherein the pulp has a water content of 30 to 95% by weight.

2. An aromatic polyamide pulp according to claim 1, in which the pulp has a surface area between 3 and 25m2/g and a freeness between 100 and 700 ml.

3. An aromatic polyamide pulp according to claim 2 in which the pulp has a freeness between 150 and 700 ml.

4. An aromatic polyamide pulp according to any one of claims 1 to 3, in which the epoxy resin is an epoxy resin having glycidyl groups which have been partially hydrolyzed.

5. A process for producing an aromatic polyamide 15 pulp according to any one of claims 1-3, comprising dispersing the aromatic polymide pulp in an aqueous epoxy resin emulsion, filtering the dispersion so obtained, and dehydrating the pulp so separated so that the pulp has a water conten, ,o from 30 to 95% by weight. 20

6. A process according to claim 4, in which the aqueous, epoxy resin emulsion is an aqueous emulsion of an epoxy resin, having glycidyl groups which have been partially hydrolyzed.

7. An, aromatic polyamide pulp substantially as hereinbefore described with reference to any one of the accompanying examples. S oiRA statuan/keop/49823 93 22.96 k v \V 30

8. A process for producing an aromatic polyamide pulp substantially as hereinbefore described with reference to any one of the accompanying examples. DATED THIS 22ND DAY OF AUGUST 1996. AKZO NOBEL N.V. By its Patent Attorneys: GRIFFITH HACK CO Fellows Institute of Patent Attorneys of Australia e *oO* o stall/uan/keep49823 93 22,8,96 INTERNATIONAL SEARCH REPORT ItratnlApiainN PCT/JP 93/01237 A. CLASSIFICATION OF SUWFCT MATI'ER IPC 5 D21H13/26 D21H17/52 006M15/55 According to lnttemaional Patent Classfication (IPC) or to both national classfication and IPC B3. FIELDS SEARCHED Minimum docuennation searched (classification system followed by classfication symnbols) IPC 5 DJ21H D06M Documentation searched other than numur documentation to the extent tha~t such documents are included in the fields searched Electronic data base consulted during the international search (nime of data base And, where lpratcal, search terms used) C. DOCUMENTS CONSIDERED TO BE RELEVANT Category Citation of document, with indication, where appropniate, of the relevant passges Relevant to claim No. A OE,A,15 20 047 (HERCULES INC.) 13 November 1 1969 see the whole document A OE,B,1O 80 513 DE BATAAFSCHE 1 PETROLEUM MAATSCHAPPIJ) 28 April 1960 see the whole document A EP,A,O 038 295 (CIBA-GEIGY AG.) 21 October 1981 A DATABASE WPI 1 Week 8726, Derwent Publications Ltd., London, GB; AN 87-181530 JP,A,62 110 984 (DAIICHI KOGYO SEIYAKU) 22 May 1987 see abstract ,r-l Furtier documents are listed in v5~e continuation of box C. [l Patent family memnbes; am listed in annex *Special categories of cited dorietnts: T lawe document published after the international filing date c o nt dianot in conflict with the application but *A'docmen deinig the general state or the art which is not ciedt tdrand 1A~e pincsple or theory uidedlyng the consdered to be of particular relevance Lnco Wasier document but publishe on or after the. internsatial document of particular relevance; the claimed invention filing date cannrot be considered novel or cannot be considerd to V document which masy throw doubts on pnort daiurns) or involve an invenstive: stp when the document is taken alone whsich is cited to esablish the publicatio date of another 'Y document of pariscular relevance; the claimed invention citation or other special reason (as specified) cannot be qorsidered to involve an Inventive step when the document referring to an oral disdlosure, use, exhibition or documenctt is combined with one or more other such docu- other meants mcnts. such combna~on being otou to a person silled document published pror to the international Oilng date but in the Vtt later than the priority date claimed W documenmt member of the same patent famil y Date of the actual completion of the international search Date of mailing of the international search report 18 November 1993 7.Z9 Name and mailing address of the ISA Europea Patent Office, P.D3. 5819 Patentlaan 2 NL.-2290 HV Ps'-:'ijk Tel. 31.7DI 4O.2040, Tx. 31 651 epo nl, Faix 3146) 340.3016 Atithonzed officer I BLAS, V Form PCT/ISA/210 (ftad 0140) (iUiY 1993) page 1 of 2 INTERNATIONAL SEARCH REPORT 1IntewA,ionid Appication No PCT/JP 93/01237 C.(Contiouanon) DOCUMENTS CONSIDER~ED TO BE RELEVANT Category Citaton of document, wi indication, where appropriate, of the relevant pamages Relevant to c;,um No. A DATABASE WPII Week 9013, Derwent Publications Ltd., London, GB; AN 90-095564 JP,A,2 047 392 (TEIJN KK) 16 February 1990 see abstract A DATABASE WPI Week 8615, Derwent Publications Ltd., London, GB; AN 86-097049 JP,A,61 041 396 (DENKI KAGAKU KOGYO KK) 27 February 1986 see abstract Form PCTASA/210 (continuaton of tecnd them) (July 1992) page 2 of 2 INTERNATIONAL SEARCH REPORT Iniioa Application No !nfonnauon on patent famly members C/P9013 Patent document Publicatin Patent faMily Publication cited in search report date member(s) date DE-A-1520047 13-11-69 GB-A- 979461 NL-c- 132844 NL-A- 276932 US-A- 3215654 DE-B-1080513 BE-A- 541693 CH-A- 349412 FR-A- 1205112 GB-A- 783740 US-A- 2872427 EP-A-0038295 21-10-81 CA-A- 1165031 i>OZ-8 JP-C- 1626665 28-11-91 JP-B- 2050949 05-11-90 JP-A- 56151721 24-11-81 US-A- 4323490 06-04-82 LIorm PC/3A1210 lpatant farnily aMI) (JulY 1993)