JP2010106049A - Water-absorbing resin particle for water-shielding tape for optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: as conventional water-absorbing resins do not always exhibit satisfactory performances because of poor absorbing performances, particularly a small absorbing rate, a water-shielding tape for an optical fiber obtained using conventional water-absorbing resins has a small water-absorbing rate for seawater and the like to cause deterioration in a cable. <P>SOLUTION: The water-absorbing resin particle (B) for a water-shielding tape for an optical fiber comprises a crosslinked polymer (A) having as essential constituting units a water-soluble vinyl monomer (a1) and/or a hydrolyzable vinyl monomer (a2) and a crosslinking agent (b), wherein the water-absorbing resin has an apparent density of 0.48-0.63 g/ml, a fractal order of 1.87-1.92, a weight-average particle size of 65-500 μm and an artificial seawater-absorbing rate of 0.33-1.67 g/g/s. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water-absorbent resin particle for an optical fiber waterproofing tape.

The optical fiber waterproofing tape absorbs an aqueous solution of high-concentration salt such as water or seawater that has entered the optical fiber cable, thereby preventing deterioration in the cable.
Water-absorbing resins used for water-resistant tapes for optical fibers include neutralized starch-acrylic acid graft polymer (Patent Document 1), partially neutralized polyacrylic acid (Patent Document 2), and amino group-containing water-soluble ethylene. A copolymer of an unsaturated unsaturated monomer-acrylic acid partial neutralized product (Patent Document 3) and the like are known.
Japanese Patent Laid-Open No. 51-125468 JP-A-62-172006 JP 2002-30270 PR

  However, these water-absorbing resins have a low absorption capacity, particularly an absorption rate, and are not necessarily satisfactory. When these water-absorbing resins are used for the optical fiber water-stopping tape, the water absorption speed of seawater or the like is low, which causes deterioration in the cable. Therefore, an object of the present invention is to provide water-absorbing resin particles for an optical fiber waterproofing tape that have an excellent absorption rate, particularly an artificial seawater absorption rate.

  The water-absorbent resin particles for an optical fiber waterproofing tape according to the present invention comprise a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2), and a cross-linked polymer (A ), The apparent density of the water-absorbent resin particles is 0.48 to 0.63 g / ml, and the fractal order of the water-absorbent resin particles is 1.87 to 1. .92, the weight average particle diameter (μm) of the water absorbent resin particles is 65 to 500, and the artificial seawater absorption rate (g / g / s) of the water absorbent resin particles is 0.33 to 1.67. This is the gist.

  The water-absorbent resin particles for an optical fiber waterproofing tape of the present invention have an extremely high absorption rate of water, saline, etc., particularly seawater. In addition, the optical fiber waterproof tape comprising the water-absorbing resin particles for the optical fiber waterproof tape of the present invention is capable of quickly absorbing water, seawater, etc. that have entered the optical fiber cable and preventing deterioration in the cable. Play.

The water-soluble vinyl monomer (a1) means a vinyl monomer having a property of dissolving at least 100 g in 100 g of water at 25 ° C.
The water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2) that becomes the water-soluble vinyl monomer (a1) by hydrolysis are not particularly limited, and examples thereof include water-soluble radicals described in JP-A-2005-075982. A polymerization monomer is mentioned. Of these, water-soluble vinyl monomers (a1) are preferable from the viewpoint of absorption performance and the like, more preferably anionic vinyl monomers, and still more preferably a vinyl group-containing carboxylic acid (salt) having 3 to 30 carbon atoms. Saturated monocarboxylic acid (salt) ((meth) acrylic acid, crotonic acid, cinnamic acid and salts thereof); unsaturated dicarboxylic acid (salt) (maleic acid, fumaric acid, citraconic acid, itaconic acid and salts thereof) ); And monoalkyl (carbon number 1 to 8) ester of the unsaturated dicarboxylic acid (maleic acid monobutyl ester, fumaric acid monobutyl ester, maleic acid ethyl carbitol monoester, fumaric acid ethyl carbitol monoester, Citraconic acid monobutyl ester and itaconic acid glycol monoester), particularly preferably unsaturated Carboxylic acid (salt), most preferably acrylic acid (salt).
In addition, (meth) acrylic acid means methacrylic acid and / or acrylic acid, acrylic acid (salt) means acrylic acid and / or acrylate, and the same applies hereinafter.

Examples of the salt include alkali metal salts such as potassium, sodium and lithium, alkaline earth metal salts such as calcium, and onium salts.
As the onium salt, those described in JP-A Nos. 2003-251178 and 2005-95357 can be used, and examples of the onium cation include a quaternary ammonium cation (I) and a tertiary phosphonium cation ( II), quaternary phosphonium cation (III), tertiary oxonium cation (IV) alkylpyridinium cation (V), ammonium cation (VI) excluding quaternary ammonium cation, etc. (Omitted).

  The quaternary ammonium (I) includes an aliphatic quaternary ammonium (I1) having 4 to 30 or more carbon atoms having an alkyl and / or alkenyl group, an aromatic quaternary having 9 to 30 or more carbon atoms. Quaternary ammonium (I2), alicyclic quaternary ammonium (I3) having 6 to 30 or more carbon atoms, imidazolinium (I4) having 6 to 30 or more carbon atoms, 5 to 30 or more carbon atoms Imidazolium (I5), tetrahydropyrimidinium having 6 to 30 or more carbon atoms (which may be combined with a substituent to form a bicyclo ring), (I6), 6 to 30 or more carbon atoms Dihydropyrimidinium (I7) and guanidinium (I8) having an imidazolinium skeleton having 8 to 30 or more carbon atoms.

  Examples of the aliphatic quaternary ammonium (I1) having 4 to 30 or more carbon atoms having an alkyl and / or alkenyl group include tetramethylammonium, tetraethylammonium, trimethylpropylammonium, dimethylpropylammonium and the like.

  Examples of the aromatic quaternary ammonium (I2) having 9 to 30 or more carbon atoms include trimethylphenylammonium, triethylphenylammonium, benzyltrimethylammonium and the like.

  Examples of the alicyclic quaternary ammonium (I3) having 6 to 30 or more carbon atoms include N, N-dimethylpyrrolidinium, N, N-diethylpyrrolidinium, N, N dimethylmorpholinium and the like. It is done.

  Examples of imidazolinium (I4) having 6 to 30 or more carbon atoms include 1,2,3-trimethylimidazolinium and 1,2,3,4-tetramethylimidazolinium.

  Examples of the imidazolium (I5) having 5 to 30 or more carbon atoms include 1,3-dimethylimidazolium, 1,2,3-trimethylimidazolium, 1,2,3,4-tetramethylimidazolium and the like. It is done.

  Tetrahydropyrimidinium having 6 to 30 or more carbon atoms (a substituent may be bonded to form a bicyclo ring) (I6) includes 1,3-dimethyltetrahydropyridinium, 1,2,3- Examples thereof include trimethyltetrahydropyridinium, 1,2,3,4-tetramethyltetrahydropyridinium and the like.

  Examples of the dihydropyrimidinium (I7) having 6 to 30 or more carbon atoms include 1,3-dimethyl-2,4- or -2,6-dihydropyrimidinium [these are 1,3-dimethyl-2, This is expressed as 4, (6) -dihydropyrimidinium, and the same expression is used hereinafter. 1,2,3-trimethyl-2,4, (6) -dihydropyrimidinium, 1,2,3,4-tetramethyl-2,4, (6) -dihydropyrimidinium and the like. .

  Examples of guanidinium (I8) having an imidazolinium skeleton having 8 to 30 or more carbon atoms include 2-dimethylamino-1,3,4-trimethylimidazolinium and 2-diethylamino-1,3,4-trimethylimidazole. Examples include linium.

Examples of the ammonium cation (VI) excluding the quaternary ammonium cation include tertiary ammonium (VI1), secondary ammonium (VI2), primary ammonium (VI3), and ammonium cation (VI4).
Examples of tertiary ammonium (VI1) include alkylammonium (trimethylammonium, triethylammonium, etc.), alkanol ammonium (trimethanolammonium, triethanolammonium, etc.), pyridinium, and the like.
Secondary ammonium (VI2) includes alkylammonium (dimethylammonium, diethylammonium, etc.) and alkanolammonium (dimethanolammonium, diethanolammonium, etc.).
Examples of the primary ammonium (VI3) include alkyl ammonium (monomethyl ammonium, monoethyl ammonium, etc.) and alkanol ammonium (monomethanol ammonium, monoethanol ammonium, etc.).

  Among these, the preferred onium cation is (I), and more preferably (I1), (I4) and (I5). These onium cations may be used alone or in combination of two or more.

Each of the water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2) may be a single structural unit or two or more structural units.
Of the water-soluble vinyl monomer (a1) and vinyl monomer (a2), the water-soluble vinyl monomer (a1) is preferable from the viewpoint of absorbability and the like, and more preferably (a1) is used alone as a structural unit.
When both water-soluble vinyl monomer (a1) and vinyl monomer (a2) are used as constituent units, the molar ratio {(a1) / (a2)} of these vinyl monomer units is preferably 75/25 to 99/1. More preferably, it is 85/15 to 95/5, particularly preferably 90/10 to 93/7, and most preferably 91/9 to 92/8. Within this range, the absorption performance is further improved.

  The crosslinking agent (b) includes at least two polymerizable double bonds and a crosslinking agent (b1) having no functional group having reactivity with a carboxyl group, at least one polymerizable double bond, A crosslinking agent (b2) having a functional group reactive with at least one carboxyl group and a crosslinking agent having a functional group reactive with at least two carboxyl groups without having a polymerizable double bond ( b3).

  Examples of the polymerizable double bond include an acryloyl group, an allyl ether group, and a vinyl ether group. The functional group having reactivity with a carboxyl group is a functional group that reacts with a carboxyl group to form an ester bond or an amide bond, and examples thereof include a hydroxyl group, an epoxy group, and an amino group.

  As the crosslinking agent (b1), a crosslinking agent (b11) having two or more (meth) acryloyl groups, a crosslinking agent (b12) having two or more vinyl ether groups, and a crosslinking agent having two or more allyl ether groups (B13) etc. are mentioned. These crosslinking agents may be used alone or in combination of two or more.

Examples of the crosslinking agent (b11) include N, N′-methylenebisacrylamide, ethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and pentaerythritol di (meth). ) Copolymerizable cross-linking agents having 2 to 10 acryloyl groups in the molecule such as acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate and polyglycerin (degree of polymerization 3 to 13) polyacrylate Can be mentioned.
Among the crosslinking agents (b11), N, N′-methylenebisacrylamide, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meta) are used from the viewpoint of the absorbability of the water absorbent resin particles. ) Acrylates are preferred, more preferably N, N'-methylenebisacrylamide, ethylene glycol di (meth) acrylate and trimethylolpropane tri (meth) acrylate, particularly preferably N, N'-methylenebisacrylamide and trimethylolpropanetri. (Meth) acrylate.

  Examples of the crosslinking agent (b12) include ethylene glycol divinyl ether, 1,4-butanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, 1,6-hexanediol divinyl ether, polyethylene glycol divinyl ether (degree of polymerization of 2 5), bisphenol A divinyl ether, pentaerythritol trivinyl ether, sorbitol trivinyl ether, polyglycerol (degree of polymerization 3 to 13) polyvinyl ether and the like.

  As the crosslinking agent (b13), there are two allyl ether groups in the molecule and no hydroxyl group, and 3-10 allyl ether groups in the molecule and no hydroxyl group. A crosslinking agent (b132) etc. are mentioned.

As the crosslinking agent (b131) having two allyl ether groups in the molecule and having no hydroxyl group, diallyl ether, 1,4-cyclohexanedimethanol diallyl ether, alkylene (2 to 5 carbon atoms) glycol diallyl ether, And polyethylene glycol (weight average molecular weight: 100 to 4000) diallyl ether and the like.
Examples of the cross-linking agent (b132) having 3 to 10 allyl groups in the molecule and having no hydroxyl group include trimethylolpropane triallyl ether, glyceryl triallyl ether, pentaerythritol tetraallyl ether, and tetraallyloxyethane. Can be mentioned.

Examples of the crosslinking agent (b2) having at least one polymerizable double bond and at least one functional group having reactivity with a carboxyl group include JP-A-1-103615 and JP-A-2000-26510. Can be used, and examples thereof include a crosslinking agent (b21) having a nonionic group and a crosslinking agent (b22) having a cationic group. These crosslinking agents may be used alone or in combination of two or more.
As the crosslinking agent (b21), a crosslinking agent (b211) having 2 allyl groups and 1 to 5 hydroxyl groups in the molecule, 3 to 10 allyl groups in the molecule and 1 to 3 hydroxyl groups. Cross-linking agent (b212) having one, cross-linking agent (b213) having no allyl group in the molecule and having a hydroxyl group {N-methylol (meth) acrylamide, etc.} and hydroxyethyl (meth) acrylate, and allyl group in the molecule And a crosslinking agent (b214) having no epoxy and having an epoxy group, such as {glycidyl (meth) acrylate}.

As a crosslinking agent (b211) having two allyl groups and 1 to 5 hydroxyl groups in the molecule, glycerin diallyl ether, trimethylolpropane diallyl ether, pentaerythritol diallyl ether, polyglycerin (degree of polymerization: 2 to 5) Examples include diallyl ether.
As the crosslinking agent (b212) having 3 to 10 allyl groups and 1 to 3 hydroxyl groups in the molecule, pentaerythritol triallyl ether and diglyceryl triallyl ether, sorbitol triallyl ether, polyglycerol (degree of polymerization) 3-13) and polyallyl ether.
Examples of the crosslinking agent (b213) having no allyl group in the molecule and having a hydroxyl group include N-methylol (meth) acrylamide and hydroxyethyl (meth) acrylate.
A glycidyl (meth) acrylate etc. are mentioned as a crosslinking agent (b214) which does not have an allyl group in a molecule | numerator and has an epoxy group.

  As the crosslinking agent (b22), a crosslinking agent having a quaternary ammonium salt {N, N, N-trimethyl-N- (meth) acryloyloxyethylammonium salt (carbonate, carboxylate, etc.) and N, N , N-triethyl-N- (meth) acryloyloxyethylammonium salt (carbonate, carboxylate, etc.)} and a cross-linking agent having a tertiary amino group {dimethylaminoethyl (meth) acrylate and (meth) And diethylaminoethyl acrylate}.

  The crosslinking agent (b2) is preferably (b21), more preferably (b211) and (b212), more preferably (b212), and particularly preferably an allyl group of 3 from the viewpoint of the absorbability of the water-absorbent resin particles. A crosslinking agent having ˜5 and 1 to 3 hydroxyl groups, most preferably pentaerythritol triallyl ether and sorbitol triallyl ether.

Examples of the crosslinking agent (b3) having no polymerizable double bond and having a functional group reactive with at least two carboxyl groups are described in JP-A-1-103615 and JP-A-2000-26510. Can be used. Examples thereof include a polyvalent glycidyl compound (b31), a polyvalent isocyanate compound (b32), a polyvalent amine compound (b33), and a polyhydric alcohol compound (b34). These crosslinking agents may be used alone or in combination of two or more.
Examples of the polyvalent glycidyl compound (b31) include ethylene glycol diglycidyl ether, glycerin diglycidyl ether, and sorbitol polyglycidyl ether.
Examples of the polyvalent isocyanate compound (b32) include 4,4′-diphenylmethane diisocyanate.
Examples of the polyvalent amine compound (b33) include ethylenediamine.
Examples of the polyhydric alcohol compound (b34) include (poly) alkylene glycol, glycerin and sorbitol.
Of the cross-linking agent (b3), a polyvalent glycidyl compound (b31) is preferable, and ethylene glycol diglycidyl ether is more preferable from the viewpoint of the absorbability of the water-absorbent resin particles.
When the crosslinking agent (b3) is used, it is general that the crosslinking reaction is allowed to proceed by heating at 100 to 230 ° C., more preferably 120 to 160 ° C. at any stage after the addition of the crosslinking agent. Further, the crosslinking agent (b3) may be used in combination of two or more in a predetermined amount range, and further in combination with (b1) and (b2).

  (B) is preferably (b1) and (b3), more preferably (b11), (b13) and (b3) from the viewpoint of the absorbability of the water-absorbent resin particles. These crosslinking agents may be used alone or in combination of two or more.

  The ratio of the crosslinking agent (b) constituting the crosslinked polymer (A) is 0 with respect to the total weight of (meth) acrylic acid (salt) and (b) from the viewpoint of the absorbability of the water-absorbent resin particles. 0.05 to 1% by weight is preferable, more preferably 0.1 to 0.8% by weight, and particularly preferably 0.1 to 0.6% by weight.

  The crosslinked polymer (A) is prepared by using a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) and a crosslinking agent (b) by a conventionally known method (JP-A-1-103615, JP-A-2000-26510). For example, Japanese Patent Laid-Open No. 2001-220415) and the like. The crosslinked polymer (A) is dried and / or pulverized in (1) a drying step and (2) a pulverizing step to obtain water-absorbing resin particles. If necessary, before the step (1), (3) a step of neutralizing the cross-linked polymer of (A), after the step of (2), (4) a step of performing a surface cross-linking treatment, (6) You may implement the process of performing additional drying, and the process of performing (7) additional grinding | pulverization. Further, if necessary, (5) the step of mixing various additives is performed either before the step (1), between the steps (1) and (2), or after the step (2). May be.

The crosslinked polymer (A) can be obtained by polymerizing the water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2) and the crosslinking agent (b) as essential constituent units.
A known polymerization method can be applied as the polymerization method, and examples thereof include aqueous solution polymerization, suspension polymerization, bulk polymerization, reverse phase suspension polymerization, and emulsion polymerization.
Among these polymerization methods, aqueous solution polymerization, suspension polymerization, reverse phase suspension polymerization and emulsion polymerization are preferable from the viewpoint of the absorbability of the water absorbent resin particles of the present invention, and more preferably aqueous solution polymerization, reverse phase suspension polymerization and Emulsion polymerization, particularly preferably aqueous solution polymerization. For these polymerizations, known polymerization initiators, chain transfer agents, solvents and the like can be used.

  Most preferred is an aqueous solution polymerization method in which a crosslinking agent (b) is added and dissolved in an aqueous monomer solution mainly composed of (meth) acrylic acid (salt). With this polymerization method, water-absorbing resin particles having excellent absorbability can be obtained.

The method for polymerizing the water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2) by an aqueous solution polymerization method may be a normal method, for example, a method of polymerizing using a radical polymerization initiator, radiation, ultraviolet rays, electron beam, etc. The method of irradiating is mentioned.
When a radical polymerization initiator is used, examples of the initiator include azo compounds [azobisisovaleronitrile, azobisisobutyronitrile, 4,4′-azobis (4-cyanovaleric acid), 2,2′- Azobis [2-methyl-N- (2-hydroxyethyl) propionamide, 2,2′-azobis (2-amidinopropane) hydrochloride, etc.], inorganic peroxides [hydrogen peroxide, potassium persulfate, ammonium persulfate, Sodium persulfate, etc.], organic peroxides [di-t-butyl peroxide, cumene hydroperoxide, etc.], redox initiators [alkali metal sulfites or bisulfites, ammonium sulfites, ammonium bisulfites, L- Reducing agents such as ascorbic acid and alkali metal persulfate, ammonium persulfate, hydrogen peroxide Like Combination, etc. of peroxide is. Two or more of these may be used in combination.

The polymerization temperature varies depending on the type of initiator used, but is preferably −10 ° C. to 100 ° C., more preferably −10 ° C. to 80 ° C. from the viewpoint of the degree of polymerization.
The amount of the initiator is not particularly limited, but is preferably from the viewpoint of the degree of polymerization with respect to the total weight of the unsaturated monomers {ie, (a1), (a2) and (b)}. It is 000001 to 3.0%, more preferably 0.000001 to 0.5%.

  In the case of aqueous solution polymerization, the polymerization concentration (% by weight) of the unsaturated monomer {that is, the water-soluble vinyl monomer (a1) and / or vinyl monomer (a2) (salt), and (b)} 10 to 40% by weight, more preferably 10 to 30% by weight, from the viewpoint of the ability to adjust the water absorption resin particles and the polymerization temperature. The amount of dissolved oxygen during polymerization depends on the amount of radical initiator added and the like, but is preferably 0 to 2 ppm, more preferably 0 to 0.5 ppm from the viewpoint of the degree of polymerization.

  When a salt is used as (a1), there is no particular limitation as long as a predetermined amount of (b) can be completely dissolved in the monomer aqueous solution, but the water solubility of (b) is poor, and in particular, the water-soluble vinyl monomer (a1) ) And / or vinyl monomer (a2) has a very low solubility in an aqueous solution, and even if a predetermined amount of (b) is added, (b) may be separated from the aqueous monomer solution and may not be subjected to predetermined crosslinking. The neutralization degree of the functional vinyl monomer (a1) and / or the vinyl monomer (a2) is 0 to 30 mol%, and is preferably further neutralized after the polymerization, if necessary, after the polymerization in an unneutralized state. If necessary, it is more preferable to neutralize after polymerization.

  In addition, when the water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2) is polymerized under the same conditions, the degree of polymerization tends to increase when the degree of neutralization is low, so that the degree of polymerization of the polymer is increased. In addition, it is preferable to carry out the polymerization in a state where the degree of neutralization is low.

When neutralizing the water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2), an alkali (C) is mixed to obtain a neutralized product. The alkali (C) includes alkali metal hydroxides, alkali metal carbonates, onium cation hydroxides and onium cation carbonates.
Examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide, lithium hydroxide and the like. Examples of the alkali metal carbonate include sodium carbonate and sodium bicarbonate. Examples of the onium cation hydroxide include tetraethylammonium hydroxide. Examples of the onium cation carbonate include 1,2,3,4-tetramethylimidazolinium monomethyl carbonate.

In the production of the crosslinked polymer (A), the average degree of polymerization of the polymer when the polymer is produced under exactly the same polymerization conditions except that no crosslinking agent is used, is preferably 5,000 to 1,000,000. It is more preferred to polymerize under polymerization conditions (type of initiator, amount of initiator, polymerization concentration of unsaturated monomer, polymerization temperature, dissolved oxygen amount, etc.) that are preferably 10,000 to 1,000,000.
When the polymerization is performed under the condition that the average degree of polymerization is 5,000 or more, the absorbability of the water-absorbent resin particles is further improved by using an appropriate amount of the crosslinking agent. The average degree of polymerization can be measured by gel permeation chromatography (GPC).

The crosslinked polymer (A) obtained by aqueous solution polymerization is obtained as a gel containing water (hydrous gel). The hydrogel is neutralized and broken if necessary, and is usually dried and then used as water absorbent resin particles.
When neutralizing the hydrogel, alkali (C) is mixed into the hydrogel of (A) to obtain a neutralized product of the hydrogel. The neutralization degree of the hydrogel obtained in this step is preferably 60 to 80 mol% of the carboxyl group in (A) from the viewpoint of the adhesiveness of the hydrogel and the safety of the water-absorbent resin particles to the human skin, More preferably, it is 65-78 mol%.
As a method of neutralizing the hydrogel of (A) with alkali (C), an aqueous solution of alkali (C) or (C) is added while chopping the hydrogel of (A) into small pieces of about 1 cm ³ or less. The method of mixing is mentioned.

As a mixing device with (C), a vertical slitting machine equipped with a cutter blade conventionally used in this step, a horizontal slitting machine equipped with a cutter blade, a cutter type crusher equipped with a rotary blade, a predetermined diameter A meat chopper equipped with an eye plate and a rotating blade can be used.
The temperature at the time of mixing may be a range conventionally used in this step, and is preferably 10 to 80 ° C. Moreover, the shearing to mix may be a conventionally well-known method, and the rotation speed of an apparatus becomes like this. Preferably it is 20-100 rpm.

When breaking the hydrous gel, a vertical slitting machine equipped with a cutter blade conventionally used in this process, a horizontal slitting slitter equipped with a cutter blade, a cutter type crusher equipped with a rotary blade, a predetermined diameter A meat chopper equipped with an eye plate and a rotating blade can be used.
The temperature at the time of fracture may be in the range conventionally used in this step, and is preferably 10 to 80 ° C. Moreover, the shearing to mix may be a conventionally well-known method, and the rotation speed of an apparatus becomes like this. Preferably it is 20-100 rpm.

  Regarding the drying method of the hydrogel, the hydrogel is subdivided to some extent with a meat chopper or cutter type crusher (the level of subdivision is about 0.5 to 20 mm square) or noodles, and if necessary, an alkali metal hydroxide, etc. After neutralizing the water-containing gel by adding air permeation drying (laminate the water-containing gel on the punching metal or screen, forcibly ventilate with hot air of 80-210 ° C) and air drying Examples include a method of putting a hydrogel into a container, aerating and circulating hot air, drying, and further drying the gel while further subdividing the gel with a machine such as a rotary kiln. Among these, air drying is preferable because efficient drying can be performed in a short time.

  Other drying methods of the hydrogel include, for example, a contact drying method in which the hydrogel is compressed and stretched on a drum dryer, and the hydrogel is poor in heat conduction. It is necessary to create a thin film of hydrogel.

In the present invention, the drying temperature at the time of drying the hydrogel varies depending on the dryer used, the drying time, and the like, but is preferably 80 to 210 ° C, more preferably 100 to 180 ° C. When the drying temperature is 210 ° C. or lower, the polymer is difficult to crosslink due to heat at the time of drying, the degree of cross-linking does not increase excessively due to thermal cross-linking, and the amount of absorption does not decrease. When the temperature is 80 ° C. or higher, drying does not take a long time and it is efficient. The drying time also varies depending on the model of the dryer to be used, the drying temperature, and the like, but is preferably 5 to 300 minutes, more preferably 5 to 120 minutes.
The dried product of the crosslinked polymer (A) thus obtained is pulverized and powdered as necessary. The pulverization method may be a normal method, and can be performed by, for example, an impact pulverizer (pin mill, cutter mill, skiller mill, ACM pulverizer, etc.) or an air pulverizer (jet pulverizer, etc.).
The resin particles (A1) obtained by pulverization have a weight average particle diameter of 65 to 500 μm, preferably 100 to 400 μm, and preferably 90% by weight or more of particles are in the range of 10 to 850 μm.

  The resin particles (A1) obtained by pulverization can be further crosslinked with a compound (D) having at least two groups capable of reacting with a carboxyl group and / or a carboxylate salt. In this method, compound (D) is added to A1), mixed, heated, subjected to a crosslinking reaction, and pulverized to obtain particulate water-absorbing resin particles.

  As the compound (D), those described in JP-A-1-103615 can be used. Examples thereof include a compound (D1) having at least two functional groups selected from the group consisting of an epoxy group, a hydroxyl group, an amino group and an isocyanate group, and a polyvalent metal compound (D2) capable of forming an ionic bridge.

As the compound (D1) having at least two functional groups selected from the group consisting of an epoxy group, a hydroxyl group, an amino group and an isocyanate group, a polyepoxy or polyglycidyl ether compound (D11), a polyol compound (D12), (poly ) An alkylene polyamine compound (D13) and the like.
Examples of the polyepoxy or polyglycidyl ether compound (D11) include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerin-1,3-diglycidyl ether, polyethylene glycol diglycidyl ether, and bisphenol A-epichlorohydrin type epoxy resin. Can be mentioned.
Examples of the polyol compound (D12) include glycerin, ethylene glycol, and propylene glycol.
Examples of the (poly) alkylene polyamine compound (D13) include ethylenediamine.

Examples of the polyvalent metal compound (D2) capable of forming ionic crosslinking include hydroxides, salts (halides, sulfates, carbonates) of alkaline earth metals (calcium, magnesium, etc.), zinc, aluminum, titanium, etc. Salt, acetate, etc.).
Specific examples include calcium chloride, zinc diacetate, and aluminum sulfate.

  Among these, preferred are polyglycidyl ether compounds and polyvalent metal compounds capable of forming ionic crosslinks.

  The addition amount of the compound (D) is preferably 0.005 to 3% by weight, more preferably 0.01 to 2% by weight, and particularly preferably 0.01 to 2% by weight with respect to the weight of (A1), from the viewpoint of the absorbability of the water absorbent resin particles. Preferably it is 0.05 to 1 weight%.

  As an example of a method of further crosslinking with the compound (D) having at least two functional groups, for example, the compound (D) is added to and mixed with the resin particles (A1), and the crosslinking reaction is performed by heating as necessary. If necessary, it is pulverized to obtain particulate water-absorbing resin particles.

  Compound (D) is added and mixed as an aqueous solution if necessary, and is usually carried out in a kneader such as a kneader or a universal mixer. The heating method may be a normal method such as a method of heating with hot air at a temperature of 100 to 230 ° C., a thin film drying method using a drum dryer heated to 100 to 230 ° C., a reduced pressure drying method, a freeze drying method, or the like. The water-absorbent resin particles obtained by crosslinking are screened and pulverized to adjust the particle size as necessary. The pulverization method is not particularly limited, and is the same as that described above.

  The weight average particle diameter (μm) of the water-absorbent resin particles of the present invention is 65 to 500 μm, preferably 100 to 400 μm, and 90% by weight or more, from the viewpoint of the absorption rate of artificial seawater suitable for optical fiber waterproofing tape. More preferably, the particles are in the range of 10 to 850 μm. When the weight average particle diameter (μm) is less than 65, blocking occurs when the artificial seawater is absorbed, and when it exceeds 500, the absorption rate of the artificial seawater is slowed.

  The weight average particle size is measured using a conventional method, for example, a low-tap test sieve shaker and a standard sieve (JIS Z8801-1: 2000), Perry's Chemical Engineers Handbook, 6th edition (Mac Glow Hill Book) -It is measured by the method described in Kanbany, 1984, page 21). That is, JIS standard sieves are combined in the order of 850 μm, 710 μm, 500 μm, 300 μm, 250 μm, 150 μm, 106 μm, 75 μm, 45 μm and 32 μm, and a tray from the top. About 50 g of the measured particles are put in the uppermost screen and shaken for 5 minutes with a low-tap test sieve shaker. Weigh the measured particles on each sieve and the pan, and calculate the weight fraction of the particles on each sieve with the total as 100% by weight. This value is the logarithmic probability paper [horizontal axis is sieve aperture (particle size ), The vertical axis is plotted on the weight fraction], and then a line connecting the points is drawn to obtain the particle diameter corresponding to the weight fraction of 50% by weight, which is defined as the weight average particle diameter.

  The water-absorbent resin particles (B) of the present invention have an apparent density of 0.48 to 0.63 g / ml from the viewpoint of the absorption rate of artificial seawater suitable for optical fiber waterproofing tape, preferably 0.50 to 0.62 g / ml, more preferably 0. 52-0.60 g / ml. If the apparent density is less than 0.48, blocking occurs when the artificial seawater is absorbed, and if it exceeds 0.63, the absorption speed of the artificial seawater becomes slow.

The apparent density is measured by the following method.
<Measurement method of apparent density>
The apparent density is measured according to JIS K3362-1998.

From the viewpoint of water absorption, the water absorbent resin particles (B) of the present invention have a fractal order of 1.87 to 1.92, preferably 1.89 to 1.91, more preferably 1.90 to 1.2. 91.
If the fractal order is less than 1.87, blocking occurs when absorbing artificial seawater, and if it exceeds 1.92, the absorption rate of artificial seawater becomes slow.

  In the present invention, the fractal order is one of indices indicating the shape of particles, that is, the irregularities of the particle surface. A small fractal order means that the external surface area of the particles is large. The fractal order is 2 if the resin particles are truly spherical with no irregularities on the surface.

In addition, said fractal order can be measured with the following method described in Unexamined-Japanese-Patent No. 2001-2935.
<Fractal order measurement method>
Using a scanning electron microscope (for example, JSM-7000F manufactured by JEOL Datum), a photograph of one water-absorbent resin particle is taken at each magnification of 25, 30, 50, and 100 times. For each of these photographs, the particle contour length and the particle projected area are determined using image analysis software (WinROOF manufactured by Mitani Corporation). Next, the common logarithm of the particle contour length and the particle projected area of each photograph is obtained. The obtained values are plotted in an XY coordinate diagram with the common logarithm of the particle contour length as the X axis and the common logarithm of the particle projection area as the Y axis, and a straight line is drawn by the method of least squares. The above straight line is drawn for each of the five water-absorbing resin particles taken out at random, and the average value of the slopes is taken as the fractal order.

  The water-absorbing resin particles (B) of the present invention have an artificial seawater absorption rate of 0.33 to 1.67 g / g / s, preferably 0.35 to 1.67 g / g / s, and more preferably 0.8. 47 to 1.38 g / g / s, particularly preferably 0.57 to 1.38 g / g / s. If the artificial seawater absorption rate is less than 0.33, the inside of the cable deteriorates due to intruded water, seawater, or the like.

The artificial seawater absorption rate is measured by the following method.
<Measurement method of artificial seawater absorption rate>
In the measuring method of 0.9M / vol% saline absorption rate according to JIS K7224-1996, except that 0.9M / vol% saline is used as artificial seawater and the weight of water absorbent resin particles is 3.0g. To measure.
Artificial seawater is prepared as follows using Aquamarine (manufactured by Yashima Pharmaceutical Co., Ltd.).
(Method for producing artificial seawater)
Dissolve Aquamarine A (powder) in about 19 L of pure water, then mix B (Liquid), mix well to make the total volume 20 L. Next, 0.13N sodium hydroxide solution is added and stirred to adjust the pH to 8.2.

  The shape of the water-absorbent resin particles (B) is not particularly limited, and is preferably in the form of particles from the viewpoint of the water absorption speed. Examples of the particles include irregularly crushed shapes, flake shapes, pearl shapes, and rice grains. .

  The content of the crosslinked polymer (A) in the water-absorbent resin particles (B) of the present invention is preferably 80% by weight or more, more preferably 85% based on the weight of (B) from the viewpoint of absorption performance. % Or more, then more preferably 90% by weight or more.

  The water absorbent resin particles of the present invention may contain an inorganic powder in addition to (A). As inorganic powder, silica, alumina, synthetic silicate, magnesium carbonate, magnesium silicate, calcium carbonate, bentonite, kaolinite, carbon black, zeolite, calcium carbonate, activated clay, oxide {silicon dioxide (orthorhombic crystal, cubic crystal) , Hexagonal crystal and monoclinic crystal, etc.), silicon oxide (amorphous, etc.), aluminum oxide, iron oxide, titanium oxide, magnesium oxide, zirconium oxide, etc.}, carbide {silicon carbide, aluminum carbide, etc.}, nitride {titanium nitride, etc. Etc.} or fine particles comprising these composite compositions. The content in each (B) is preferably 20% by weight or less, more preferably 15% by weight or less, and still more preferably 10%, based on the weight of (A), from the viewpoint of absorption performance. % By weight or less.

Examples of the method for producing the water-absorbent resin particles of the present invention satisfying the above conditions are as follows. That is, in the conventionally known method for producing water-absorbent resin particles by aqueous solution polymerization, the foaming agent (E) is obtained by including one step or two or more steps selected from the group consisting of the following first step to fourth step (A). It is a manufacturing method to mix with.
1st process: The process of mixing the hydrogel of (A), and (E) 2nd process: The process of mixing with (E), drying the hydrogel of (A).
Third step: Step of mixing dried (A) with pulverizing (E) Fourth step: Step of mixing resin particles (A1) and (E) comprising (A)

When (E) is heated to a temperature of 70 to 210 ° C., the blowing agent (E) is a gas of 50 to 300 ml (0 ° C., 1 atm) per 1 g of (E) in 1 to 300 minutes. Means a compound that occurs.
From the viewpoint of the absorption performance of the water-absorbent resin particles of the present invention, the temperature at which (E) generates the gas is preferably 80 to 190 ° C, more preferably 90 to 170 ° C. Moreover, it is preferable that (E) generate | occur | produces the said gas by the heating for 2-120 minutes from a viewpoint of the absorption performance of this water absorbing resin particle. Further, from the viewpoint of the absorption performance of the water-absorbent resin particles, the amount of gas generated is preferably 60 to 290 ml / g, more preferably 70 to 280 ml / g, and particularly preferably 80 to 250 ml / g.

  Examples of the foaming agent (E) include a foaming agent (E1) that generates nitrogen by heating, a foaming agent (E2) that generates carbon dioxide by heating, and the like.

Examples of the foaming agent (E1) include an azo compound (E11), a sulfonyl hydrazide compound (E12), and a nitroso compound (E13).
Examples of the azo compound (E11) include azodicarbonamide and azobisisobutyronitrile.
Examples of the sulfonyl hydrazide compound (E12) include p-toluenesulfonyl hydrazine and p, p′-oxybis (benzenesulfohydrazide).
Examples of the nitroso compound (E13) include N, N′-dinitrosopentamethylenetetramine.
Among (E1), (E11) and (E12) are preferable from the viewpoint of the absorption performance of the water-absorbing resin particles, and azodicarbonamide and p, p′-oxybis (benzenesulfohydrazide) are more preferable.

Examples of the foaming agent (E2) include ammonium carbonate and sodium hydrogen carbonate.
Among (E2), sodium hydrogencarbonate is preferable from the viewpoint of the absorption performance of the water absorbent resin particles.

  As the foaming agent (E), (E1) is preferable from the viewpoint of the absorption performance of the water-absorbent resin particles. Moreover, (E1) and / or (E2) may be used alone or in combination of two or more.

  The amount of the foaming agent (E) used is preferably 0.1 to 20% by weight based on the total weight of (a1), (a2) and (b) from the viewpoint of the absorption performance of the water-absorbent resin particles, More preferably, it is 0.5 to 15% by weight, particularly preferably 1.0 to 13% by weight, and most preferably 2.0 to 10% by weight.

  When using the foaming agent (E), it may be used as a dispersion of (E). In this case, water, an aqueous solvent (such as methanol, ethanol, isopropylene, and acetone) can be used as the dispersion medium.

The first step is a step of mixing the hydrogel (A) and (E).
This step may be performed simultaneously with the step (3) of neutralizing the hydrous gel of (A).
In this step, the mixing method of (E) includes a method of adding and mixing the dispersion liquid of (E) or (E) while chopping the hydrogel of (A) into pieces of about 1 cm ³ or less. .
When the step of mixing the hydrogel of (A) and (E) is performed simultaneously with the step of neutralizing the hydrogel of (A), the step immediately before mixing of the hydrogel of (A) and (C) , (A) The water-containing gel may be neutralized, or (A) the water-containing gel may be neutralized immediately after neutralization.

When the dispersion liquid (E) is used, the concentration of (E) is preferably 10 to 70% by weight, more preferably 20 to 60% by weight, and particularly preferably 30 to 30% by weight based on the weight of the dispersion liquid (E). 50% by weight.
As a mixing device, a vertical slitter with a cutter blade used in the process of mixing a conventional hydrogel and (C), a transverse slitter with a cutter blade, a cutter type crusher with a rotary blade A meat chopper equipped with a machine, a pan with a predetermined diameter and a rotary blade can be used.
The temperature at the time of mixing may be a range performed in the step of mixing the conventional hydrogel and (C), and is preferably 10 to 80 ° C. Moreover, the shear to mix may be the same as the case where the conventional hydrogel and (C) are mixed, and the rotation speed of an apparatus becomes like this. Preferably it is 20-100 rpm.

In the present invention, when the hydrogel of (A) is crushed and dried, the hydrogel of (A) is adhered to each other, and the mixer, and for the purpose of preventing the hydrogel of (A) from adhering to the dryer, as necessary. You may mix a well-known mold release agent with the dispersion liquid of (E).
Release agents include inorganic powders [calcium carbonate, aluminum hydroxide, aluminum oxide, silicon dioxide, hydrophobized silicon dioxide, titanium oxide, etc.], natural product-derived powders [wheat flour, rice flour, starch, carboxymethylcellulose] , Hydroxyethyl cellulose, hydroxypropyl cellulose, etc.], synthetic polymer or synthetic resin powder [polyvinyl alcohol, polyester, silicone resin, fluorine resin, polyethylene, polypropylene, acrylic resin, etc.], anionic surfactant [lauryl sulfate] Triethanolamine, sodium lauryloxypolyethyleneoxysulfate, sodium lauryl sulfosuccinate, sodium lauroyl sarcosine, sodium α-olefin sulfonate, sodium lauryl phosphate, N- 椰Oil fatty acid acyl-L-glutamate monosodium, sodium lauryl sulfoacetate, etc.], nonionic surfactant [1: 1 type coconut oil fatty acid diethanolamide, lauryl dimethylamine oxide, glyceryl monostearate, polyethylene glycol monostearate, Polyethylene glycol distearate, sorbitan monolaurate, polyoxyethylene sorbitan monolaurate, nonylphenol polyoxyethylene, octylphenol polyoxyethylene, dodecylphenol polyoxyethylene, etc.], cationic surfactants [stearyltrimethylammonium chloride, distearyldimethylammonium chloride] , Ethyl sulfate lanolin fatty acid aminopropylethyldimethylammonium etc.], amphoteric activator [coconut oil fat Amidopropyldimethylaminoacetic acid betaine, lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, etc.], polymer activator [cationized cellulose, polyethylene glycol, polypropylene glycol, polyacryl Examples thereof include sodium acid surfactants, and known silicon surfactants and fluorine surfactants. Among these release agents, inorganic powders, anionic surfactants and nonionic surfactants are preferred.

  When the release agent is powdery, the addition amount of the release agent is based on the total weight of (a1), (a2) and (b), from the viewpoint of reducing dust generation and absorption performance of the water absorbent resin particles. It is 0 to 50% by weight, preferably 0.001 to 30% by weight. In addition, when a powder-form mold release agent is used, you may isolate | separate and collect | recover an excess mold release agent in the arbitrary steps after gel crushing. The addition amount when the release agent to be added is liquid is 0 to 5% by weight with respect to the total weight of (a1), (a2) and (b), preferably from the viewpoint of the absorbability of the water absorbent resin particles, 0.0001 to 3% by weight.

  In the second step, the hydrogel of (A) is contact-dried (such as by compressing and stretching the hydrogel on a drum dryer), and air-permeable drying (the hydrogel is laminated on a punching metal or a screen to force (For example, dry by blowing hot air at 80 to 210 ° C.) and dry by drying (Put water-containing gel in a container, dry by circulating hot air and dry it, and further dry the gel with a machine such as a rotary kiln) It is a process of mixing with (E) while drying by the method of. Among these, air drying is preferable because efficient drying can be performed in a short time.

  The drying temperature varies depending on the dryer used, the drying time, and the like, but is preferably 80 to 210 ° C, more preferably 100 to 180 ° C, from the viewpoint of the drying time and the absorbability of the water absorbent resin particles. Regarding the drying time, it varies depending on the model of the dryer to be used, the drying temperature, etc., but is preferably 5 to 300 minutes, more preferably 5 to 120 minutes, from the viewpoint of the drying time and the absorbability of the water-absorbent resin particles. .

In this step, examples of the mixing method (E) include a method of adding and mixing (E) or the dispersion liquid (E) while drying the hydrogel of (A).
When mixing (E) with the hydrogel of (A), the stage immediately before drying the hydrogel of (A), the stage of drying the hydrogel of (A), and drying the hydrogel of (A) Mixing may be performed at any of the immediately following stages, and is preferably the stage immediately before drying the hydrogel of (A).
When the dispersion liquid (E) is used, the concentration of (E) is preferably 10 to 70% by weight, more preferably 20 to 60% by weight, and particularly preferably 30 to 30% by weight based on the weight of the dispersion liquid (E). 50% by weight.

As a mixing device, in the case of the stage immediately before drying the hydrogel of (A), it is equipped with a vertical slitting slitter equipped with a cutter blade used in the process of mixing the conventional hydrogel and (C), and a cutter blade. A cross-cut slitter, a cutter-type crusher equipped with a rotary blade, a meat chopper equipped with a pan with a predetermined diameter and a rotary blade can be used. The temperature at the time of mixing may be a range performed in the step of mixing the conventional hydrogel and (C), and is preferably 10 to 80 ° C. Moreover, the shear to mix may be the same as the case where the conventional hydrogel and (C) are mixed, and the rotation speed of an apparatus becomes like this. Preferably it is 20-100 rpm.
The mixing apparatus at the stage of drying the hydrogel of (A) is not particularly limited as long as the dried hydrogel of (A) and (E) can be mixed uniformly. For example, in a conventional drying process, An apparatus such as adding the charging line (E) to the dryer to be used can be used. The temperature at the time of mixing may be in the range used in the conventional drying process.
The stage immediately after drying the hydrogel of (A) is not particularly limited as long as the dried hydrogel of (A) and (E) can be mixed uniformly. For example, in the transfer line immediately after the conventional drying process. An apparatus for adding a preparation line (E) can be used. The temperature at the time of mixing may be in the range used in the conventional drying process.

The third step is a step of mixing dried (A) with (E) while crushing.
The pulverization method may be a conventionally known method, for example, an impact pulverizer (pin mill, cutter mill, skiller mill, ACM pulverizer, etc.) or an air pulverizer (jet pulverizer, etc.).
In this step, the mixing method of (E) includes a method of adding and mixing the dispersion of (E) while pulverizing the dried (A) into small pieces of about 1 mm ³ or less.
When mixing (E) with dried (A) while pulverizing, the stage immediately before pulverizing dried (A), the stage pulverizing dried (A), immediately after pulverizing dried (A) Mixing may be carried out at any of the stages, preferably the stage immediately before pulverizing the dried (A) and the stage pulverizing the dried (A).
The concentration of the dispersion (E) is preferably 10 to 70% by weight, more preferably 20 to 60% by weight, and particularly preferably 30 to 50% by weight based on the weight of the dispersion (E).
The mixing device for mixing at the stage immediately before pulverization is not particularly limited as long as the dried (A) and (E) can be mixed uniformly. For example, in a conventional pulverizer, immediately before pulverizing the dried (A). In this part, a preparation line (E) can be provided and added. The temperature at the time of mixing may be within the range performed in the conventional step of pulverizing the dried (A).
The apparatus for mixing the dried (A) while pulverizing is not particularly limited as long as the pulverized resin particles (A1) and (E) can be mixed uniformly, but the pulverizer used in the conventional pulverization process is not limited. An apparatus such as adding a preparation line (E) can be used. The temperature and shear at the time of mixing may be within a known range performed in the conventional step of pulverizing the dried (A).
As a mixing device for mixing at the stage immediately after pulverization, a Nauter type mixer, a kneader type mixer, a paddle type mixer, a V type mixer, a ribbon type mixer, a screw type mixer, an airflow type mixer, etc. are used. it can. The temperature and shear at the time of mixing may be in a known range conventionally used in the surface crosslinking step.

The fourth step is a step of mixing the resin particles (A1) and (E) made of (A).
This step may be performed simultaneously with the step (4) of performing the surface crosslinking treatment.
In this step, examples of the mixing method (E) include a method in which the resin particles (A1) and (E) made of (A) and the dispersion liquid of (E) are added and mixed.
As the step of mixing (E) with the resin particles (A1) comprising (A), when (A1) is subjected to surface cross-linking, (A1) is subjected to surface cross-linking immediately before (A1) is subjected to surface cross-linking. May be mixed in any of the steps immediately after the surface crosslinking of (A1), preferably the step immediately before the surface crosslinking of (A1) and the step of (A1) surface crosslinking, Preferably, it is the step immediately before surface cross-linking (A1). When (A1) is not surface-crosslinked, it may be carried out at any stage as long as it is a process after obtaining (A1).
When the dispersion liquid (E) is used, the concentration of (E) is preferably 10 to 70% by weight, more preferably 20 to 60% by weight, and particularly preferably 30 to 30% by weight based on the weight of the dispersion liquid (E). 50% by weight.
As a mixing apparatus at the stage of surface cross-linking (A1), a Nauter type mixer, a kneader type mixer, a paddle type mixer, a V type mixer, a ribbon type mixer, a screw type, which are conventionally used in this process. A mixer, an airflow type mixer, etc. can be used. The temperature and shear at the time of mixing may be within a known range in the conventional surface crosslinking step.
The mixing apparatus at the stage immediately before and after the surface crosslinking of (A1) is the same as the mixing apparatus that can be used at the stage of (A1) surface crosslinking, and the conditions for mixing are also the same.

  Among these, from the viewpoint of the absorption performance of the water-absorbent resin particles, the first step and the fourth step are preferable as the step of mixing (A) and (E), more preferably the first step.

After mixing (E), the manufacturing method which passes through the process of heating as needed is preferable because it is easy to obtain the water-absorbent resin particles of the present invention. The step of heating after mixing (E) may be at any timing, and the heating device is not particularly limited, and a normal heating dryer such as a hot air dryer, fluidized bed dryer, nauter dryer, rotary kiln, etc. Etc. can be used. The heating temperature varies depending on the model to be used, the heating time, and the like, but is 70 to 210 ° C., and preferably 80 to 190 ° C. from the viewpoint of the efficiency of generating gas from (E) and the absorbability of the water absorbent resin particles. More preferably, it is 90-170 degreeC. The heating time also varies depending on the model used and the drying temperature, but is preferably 1 to 300 minutes, more preferably 2 to 120 minutes.
When mixing before a drying process, since a drying process can be utilized as this heating process, the process of heating especially is unnecessary.
Moreover, when mixing before the process of surface-crosslinking treatment, since the heating process of surface crosslinking treatment can be utilized as a heating process, the process of heating in particular is unnecessary.

  The water-absorbent resin particles of the present invention exhibit excellent performance as a waterproofing agent for optical fibers and cables for underground and sea floors.

The water-absorbent resin particles are used as a water-stopping agent for optical fiber cables as they are, or after being kneaded with rubber and / or thermoplastic resin, or formed into a non-woven fabric or paper.
The water-absorbing resin particles of the present invention can be used as a water-stopping material for optical fiber cables in the same manner as known water-absorbing resin particles (Japanese Patent Laid-Open Nos. 8-283697 and 9-297248, etc.).

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to this.

Example 1
In a 2-liter beaker, 300 g of acrylic acid, 1.0 g of pentaerythritol triallyl ether and 660 g of ion-exchanged water were mixed with stirring to prepare an aqueous acrylic acid solution, and the temperature was adjusted to 8 ° C.
The acrylic acid aqueous solution was put into a 1.5 liter adiabatic polymerization tank, and the dissolved oxygen amount in the acrylic acid aqueous solution was adjusted to 0.1 ppm or less through nitrogen in the aqueous solution. To this heat insulation polymerization layer, 2.0 wt% 2,2′-azobis {2-methyl-N- (2-hydroxyethyl) -propionamide} (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-086) 4.65 g of aqueous solution, 1.23 g of 1.0 wt% aqueous hydrogen peroxide, 4.65 g of 1.0 wt% L-ascorbic acid aqueous solution and 0.45 g of 0.1 wt% iron (II) sulfate heptahydrate aqueous solution And nitrogen bubbling into the aqueous solution was continued until polymerization started. After confirming that the polymerization started and the viscosity of the acrylic acid aqueous solution started to rise, the nitrogen aeration was stopped and the polymerization was carried out for 6 hours. When the temperature of the aqueous acrylic acid solution was measured with a hot spot thermometer, the highest temperature reached 98 ° C.
After taking out the block-like crosslinked hydrous gel from the adiabatic polymerization tank and using a small meat chopper (Royal) to subdivide the gel into noodles with a thickness of 3 to 10 mm at 60 rpm at room temperature. , 250 g of a 48 wt% sodium hydroxide (reagent grade) aqueous solution (the neutralization degree of the carboxyl group derived from acrylic acid in the cross-linked polymer is 72 mol%) is added, and the meat chopper is mixed and subdivided under the same conditions. The carboxyl group of polyacrylic acid in the crosslinked polymer was neutralized. Further, 36.7 g of p, p′-oxybis (benzenesulfohydrazide) (manufactured by Eiwa Kasei Kogyo: Neocerbon N # 5000) {10% by weight based on the total weight of acrylic acid (salt) and the crosslinking agent} The meat chopper was uniformly mixed and subdivided with the hydrous gel under the same conditions.
This hydrogel was laminated on a SUS screen having an opening of 850 μm with a thickness of 5 cm, and a small air-permeable dryer (manufactured by Yako Electric Manufacturing Co., Ltd.) was used to supply a supply air temperature of 160 ° C. and a wind speed of 1 Under a condition of 0.5 m / sec, the water-containing gel was passed through for 40 minutes, and the water-containing gel was dried by heating to obtain a dried product having a water content of about 4%.
The dried product was pulverized using a home mixer, and a particle having a particle size of 32 to 710 μm (400 to 22 mesh) was collected using a sieve to obtain resin particles.
While stirring 100 g of the obtained resin particles, a solution composed of 0.01 g of ethylene glycol diglycidyl ether, 0.9 g of water and 0.46 g of propylene glycol was used at room temperature using a Nauter mixer (manufactured by Hosokawa Micron Corporation). The mixture was added and mixed under the condition of 50 rpm, and heated reaction at 140 ° C. for 40 minutes using a smooth air dryer (manufactured by Tabai Espec Co., Ltd.) to obtain the water absorbent resin particles (1) of the present invention.

Example 2
The water-absorbent resin particles (1) obtained in Example 1 were pulverized using a household mixer, and the particles having a particle size of 300 μm (50 mesh) or less were collected using a sieve to obtain the water-absorbent resin particles of the present invention. (2) was obtained.

Example 3
In Example 1, p, p'-oxybis (benzenesulfohydrazide) was used in the same manner as in Example 1 except that 73.4 g {20% by weight based on the total weight of acrylic acid (salt) and the crosslinking agent}. Thus, water-absorbent resin particles (3) of the present invention were obtained.

Example 4
In a 1 liter beaker, 100 g of acrylic acid, 272.2 g of ion-exchanged water and 0.13 g of ethylene glycol diglycidyl ether were added and mixed to obtain a uniform solution. While cooling the beaker with an ice bath, 100 g of 40 wt% sodium hydroxide aqueous solution was added to neutralize a part (72 mol%) of acrylic acid. After the neutralized monomer solution was cooled to 5 ° C., 0.2 g of potassium persulfate was added as a polymerization initiator to prepare a monomer aqueous solution.
In a 2 liter separable flask equipped with a stirrer and a condenser (cooler), 1000 ml of cyclohexane and polyoxyethylene octyl phenyl ether phosphate as a dispersant (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf A210G) 2 0.5 g was added and stirred while adjusting the temperature to 60 ° C. using a hot water bath to dissolve the dispersant in cyclohexane.
After reducing the dissolved oxygen of cyclohexane to 0.1 ppm or less through nitrogen in a cyclohexane liquid in a separable flask, stirring the cyclohexane using a stirrer, and then adding 400 g of the monomer aqueous solution at 6.6 g / min using a dropping funnel. The mixture was added dropwise over 1 hour, reverse phase suspension polymerization was performed at a polymerization temperature of 60 ° C., and after completion of the dropwise addition of the monomer aqueous solution, the temperature was further adjusted to 60 ° C. for 2 hours to complete suspension polymerization and then cooled to 30 ° C. Thus, a spherical hydrous gel was obtained in cyclohexane.
After the rotation of the stirrer was stopped and the produced hydrogel was allowed to settle, cyclohexane was removed by decantation, and the remaining hydrogel was washed twice with cyclohexane to remove the dispersant adhering to the hydrogel.
The obtained spherical water-containing gel was spread on a release paper, and dried for 2 hours with a 80 ° C. vacuum dryer (degree of vacuum: 10,000 to 20,000 Pa).
To 100 g of the obtained dried product, 48.3 g of an aqueous dispersion of 30 wt% azodicarbonamide {15 wt% based on the total weight of acrylic acid (salt) and crosslinking agent} was added, and a small air-permeable dryer was used. After air permeation for 30 minutes under the conditions of a supply air temperature of 205 ° C. and a wind speed of 1.5 m / sec, the mixture is pulverized using a home-use mixer, and the particles are 32 to 710 μm (400 to 22 mesh) using a sieve. The thing of a diameter was extract | collected and the water absorbent resin particle (4) of this invention was obtained.

Example 5
In Example 1, 36.7 g of p, p′-oxybis (benzenesulfohydrazide) was added to 1.23 g of azodicarbonamide (manufactured by Eiwa Kasei Kogyo Co., Ltd., trade name: VINYHALL AC # 3) {acrylic acid (salt) and a crosslinking agent The water-absorbent resin particles (5) of the present invention were obtained in the same manner as in Example 1 except that the content was set to 0.5% by weight with respect to the total weight.

Example 6
The water-absorbent resin particles (1) obtained in Example 1 were collected with a sieve using a sieve having a particle size of 150 to 710 μm (100 to 22 mesh) to obtain the water-absorbent resin particles (6) of the present invention. It was.

Example 7
The water-absorbent resin particles (1) obtained in Example 1 were pulverized using a home-use mixer, and those having a particle size of 150 μm (100 mesh) or less were collected using a sieve and the water-absorbent resin particles of the present invention were collected. (7) was obtained.

Example 8
To the water-absorbent resin particles (2) obtained in Example 2, 2% by weight of silicon dioxide {made by Nippon Aerosil Co., Ltd., trade name: Aerosil 200PE} is added to the water-absorbent resin particles, and blended uniformly. As a result, water-absorbent resin particles (8) of the present invention were obtained.

Comparative Example 1
The water-absorbent resin particles (1) obtained in Example 1 were collected using a sieve to obtain a particle size of 500 μm (30 mesh) or more to obtain comparative water-absorbent resin particles (H1).

Comparative Example 2
The water-absorbent resin particles (1) obtained in Example 1 were pulverized using a home-use mixer, and those having a particle size of 32 μm (400 mesh) or less were collected using a sieve to compare the water-absorbent resin particles for comparison. (H2) was obtained.

Comparative Example 3
Comparative water-absorbent resin particles (H3) were obtained in the same manner as in Example 1, except that 36.7 g of p, p′-oxybis (benzenesulfohydrazide) was not added.

Comparative Example 4
It was produced by the method described in JP-A-1-294703, that is, the following method. To a 500 ml four-necked separable flask equipped with a stirrer, reflux condenser, dropping funnel and nitrogen introducing tube, 180 ml of normal heptane was taken, and 3.0 g of erythritol stearate was added. The solution was heated to 60 ° C. while introducing nitrogen gas to dissolve the ester and then cooled to 25 ° C. Separately, 20 g of acrylic acid was neutralized with 41.5 g of a 20.1% by weight aqueous sodium hydroxide solution, and 0.03 g of potassium persulfate was dissolved. After this acrylate aqueous solution was added to the above separable flask and sufficiently dispersed, the temperature was raised to 60 ° C., and then held for 2 hours to carry out a polymerization reaction. After water and normal heptane are azeotroped to remove water, the system temperature is set to 40 ° C. or lower, and the solvent is distilled off by drying under reduced pressure, whereby comparative water-absorbent resin particles having a particle size of 40 to 50 μm (H4 )

Comparative Example 5
It was produced by the method disclosed in JP-A-2001-2935, that is, the following method. To a mixed solution of 207.7 g of acrylic acid and 13.5 g of water, 346.2 g of a 25 wt% aqueous sodium hydroxide solution was added while cooling. A monomer aqueous solution was prepared by adding 0.104 g of potassium persulfate and 0.021 g of sodium hypophosphite to the resulting solution. Into a three-liter four-necked round bottom flask equipped with a stirrer, reflux condenser, thermometer and nitrogen gas inlet tube, 624 g of cyclohexane was placed, and polyoxyethylene octyl phenyl ether phosphate (Daiichi Kogyo Seiyaku Co., Ltd. product) After adding and dissolving 1.56 g of Prisurf A210G), nitrogen gas was introduced while stirring at 400 rpm. Next, the mixture was heated to 75 ° C., and the monomer aqueous solution prepared above was introduced thereto at an almost constant rate over 60 minutes. After completion of the introduction of the monomer aqueous solution, polymerization was further performed at 75 ° C. for 30 minutes, and then water was removed by azeotropy with cyclohexane. When stirring was stopped when the water content of the produced resin reached about 20%, the resin particles settled, and the resin particles and cyclohexane were separated by decantation. 40 g of the obtained resin particles (on a dry basis) and 140 g of cyclohexane are placed in a 300 ml eggplant flask, and a cyclohexane solution 3 containing 0.35% by weight of glycerol polyglycidyl ether (Nagase Kasei Kogyo Co., Ltd., Denacol EX314). After adding 4 g, it was heated at 60 ° C. and held for 30 minutes. It was then heated and held for 30 minutes under reflux of cyclohexane. The resin particles were obtained by filtration and dried under reduced pressure at 80 ° C. to obtain water absorbent resin particles (H5).

Examples 9-16
Resin for urethane-based paint [polyester-based urethane resin, trade name: Samprene IB-1700D, manufactured by Sanyo Chemical Industries Ltd.] 29.0 g, dibutyltin dilaurate 1.0 g, water-absorbent resin particles obtained in Examples 1-8 (1)-(8) 60.0g and methyl ethyl ketone 10.0g were mix | blended, and it heated and mixed at 70 degreeC for 3 hours, and obtained each coating material. This is applied to a polyester-based non-woven fabric [weight per unit area: 40 g / m ² : manufactured by Toray Industries, Inc.] with a bar coater, dried at 105 ° C. for 3 minutes, and a solid content of 50 g / m ² coating and thickness Water-stopping tapes (1) to (8) having a thickness of 500 μm were obtained.

Comparative Examples 6-10
In Example 9, water-stopping tapes (H1) to (H5) were obtained in the same manner as in Example 9 except that the water-absorbing resin particles (H1) to (H5) were used instead of the water-absorbing resin particles (1). It was.

  About the water-absorbent resin particles (1) to (8) and the water-absorbent resin particles (H1) to (H5) obtained in Examples 1 to 8 and Comparative Examples 1 to 5, artificial seawater absorption rate, apparent density, and fractal order And the weight average particle diameter was measured. The results are shown in Table 1.

  The water absorption speed of the water stop tapes (1) to (5) and (H1) to (H5) prepared in Examples 9 to 16 and Comparative Examples 6 to 10 was evaluated. The evaluation method is as follows.

1) Evaluation method of water absorption speed (sec) The water-stopping tape was cut into a size of 10 cm × 10 cm to obtain a test sample. Place this test sample on a horizontal table so that the water-absorbent resin composition application surface is on top, and place 1 ml of artificial seawater [Aquamarine; Yasu Pharmaceutical Co., Ltd. The pipette was dropped within 2 seconds, and the time from the start of dripping until the total amount of artificial seawater was absorbed was measured.

The evaluation results are shown in Table 2.
In Table 2, it turns out that the water stop tape of an Example has the water absorption speed | velocity of the favorable artificial seawater. That is, it can quickly absorb water, seawater and the like that have entered the optical fiber cable to prevent deterioration in the cable, and exhibits excellent performance as a water-stopping agent for optical fibers in the underground and undersea.

  The water-absorbing resin particles for an optical fiber waterproofing tape of the present invention are water-absorbing resin particles having an excellent absorption rate for water, saline, etc., particularly seawater. Therefore, when the water-absorbent resin particles of the present invention are used in a water-resistant tape for optical fibers, it is possible to quickly absorb water, seawater, etc. that have entered the optical fiber cable and prevent deterioration in the cable.

Claims (3)

  Water-absorbing resin for optical fiber waterproofing tape comprising water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and cross-linked polymer (A) having cross-linking agent (b) as essential constituent units In the particles, the apparent density of the water absorbent resin particles is 0.48 to 0.63 g / ml, the fractal order of the water absorbent resin particles is 1.87 to 1.92, and the weight average particle diameter of the water absorbent resin particles is (Μm) is 65 to 500, and the water absorption resin particles for optical fiber waterproofing tape (B) have an artificial seawater absorption rate (g / g / s) of 0.33 to 1.67.   The water-absorbent resin particles according to claim 1, wherein the water-absorbent resin particles are produced by a production method including a mixing step of a crosslinked polymer (A) and a foaming agent (E) that generates gas by heating. Water-absorbent resin particles for optical fiber waterproofing tape.   An optical fiber waterproofing tape comprising the water-absorbent resin particles according to claim 1 or 2.