JP2015145488A - water-absorbing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-absorbing resin composition having excellent workability and initial wettability.SOLUTION: A water-absorbing resin composition comprises, based on thermoplastic resin 100 pts.mass, water-absorbing polyalkylene oxide modified product 10-50 pts.mass, ethylene (meth) acrylic acid copolymer 10-80 pts.mass and crystal nucleating agent 0.1-1.0 pts.mass.

Description

  The present invention relates to a water absorbent resin composition having excellent wettability.

  Conventionally, inexpensive olefin-based resins have been widely used after being processed into various forms. However, since olefin-based resins are inherently hydrophobic materials, it has been necessary to improve antistatic properties, surface printability, and wettability. For this purpose, various methods such as a method of chemically treating the surface of a polyolefin molded body with a chemical agent, a method of oxidizing the surface of the molded body by a technique such as corona discharge treatment, plasma treatment, or flame treatment have been tried. ing. However, these methods require a special apparatus and are not always sufficient in improving paintability and adhesion by improving wettability of the surface.

  Also, in order to make the effect of imparting hydrophilicity permanent, various hydrophilic resins are mixed with polyolefin resin, melt-kneaded with a kneader, Banbury mixer, extruder, etc., and then molded into pellets or the like. Proposed. As a hydrophilic resin used at that time, for example, a water-soluble resin typified by polyethylene oxide having thermoplasticity has been proposed (Patent Document 1). However, when used repeatedly, water-soluble components flow out, and the effect may not be permanent. Therefore, it has also been proposed to use a water-absorbing resin excellent in moisture retention. For example, a method of mixing a thermoplastic water-absorbent resin obtained by modifying polyalkylene oxide with polyisocyanate, a polyolefin resin, and polyamide or polyoxymethylene having a melting point of less than 200 ° C. has been proposed (Patent Document 2). Furthermore, a method using an ethylene (meth) acrylic acid copolymer instead of polyamide or polyoxymethylene has been proposed in order to improve processability (Patent Document 3).

JP-A-6-25541 JP-A-1-163229 JP 7-173385 A

  The water-absorbent resin compositions obtained by the methods described in Patent Documents 2 and 3 have long-lasting hydrophilic effects, but have low initial water absorbency and wettability, and have a problem that it takes time to develop the effects. In order to increase the initial water absorption rate, it is effective to increase the amount of the thermoplastic water-absorbing resin added, but with the increase of the amount added, the melt viscosity of the composition itself increases and the processing characteristics deteriorate, There were problems such as a large dimensional change during maximum water absorption.

  An object of the present invention is to provide a water absorbent resin composition having excellent initial wettability and excellent processing characteristics without increasing the amount of thermoplastic water absorbent resin added.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a water-absorbing resin comprising a thermoplastic resin, a water-absorbing polyalkylene oxide-modified product, an ethylene (meth) acrylic acid copolymer, and a crystal nucleating agent. The composition was found to be excellent in initial wettability and processing characteristics, and further investigations were made to complete the present invention.

That is, the present invention includes, for example, the subject matters described in the following sections.
Item 1.
(A) 100 parts by mass of a thermoplastic resin,
(B) 10 to 50 parts by mass of a water-absorbing polyalkylene oxide modified product,
(C) ethylene (meth) acrylic acid copolymer 10-80 parts by mass, and (D) crystal nucleating agent 0.1-1.0 part by mass,
A water-absorbent resin composition comprising:
Item 2.
Item 2. The water-absorbent resin composition according to Item 1, wherein the thermoplastic resin is at least one polyolefin resin selected from the group consisting of polyethylene and polypropylene.
Item 3.
Item 3. The water absorbent resin composition according to Item 1 or 2, wherein the water absorbent polyalkylene oxide modified product is a water absorbent polyalkylene oxide modified product obtained by reacting a polyalkylene oxide compound, a diol compound, and a diisocyanate compound.
Item 3a.
The polyalkylene oxide compound is polyethylene oxide, polypropylene oxide, polybutylene oxide, ethylene oxide / propylene oxide copolymer, ethylene oxide / butylene oxide copolymer, propylene oxide / butylene oxide copolymer, and ethylene oxide / propylene oxide / butylene oxide. Item 4. The water-absorbent resin composition according to Item 3, which is at least one selected from the group consisting of copolymers.
Item 3b.
The diol compound is ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, Item 3. The water absorbent resin composition according to Item 3 or 3a, which is at least one selected from the group consisting of 1,5-pentanediol, 1,6-hexanediol, and 1,9-nonanediol.
Item 3c.
The diisocyanate compound is 4,4′-diphenylmethane diisocyanate (MDI), 1,6-hexamethylene diisocyanate (HDI), dicyclohexylmethane-4,4′-diisocyanate (HMDI), 3-isocyanatomethyl-3, It is at least one selected from the group consisting of 5,5-trimethylcyclohexyl isocyanate (IPDI), 1,8-dimethylbenzole-2,4-diisocyanate, and 2,4-tolylene diisocyanate (TDI) The water-absorbent resin composition according to Item 3, 3a, or 3b.
Item 4.
Item 4. The water absorbent resin composition according to any one of Items 1, 2, 3, 3a, 3b, and 3c, wherein the water absorbent ability of the modified water absorbent polyalkylene oxide is 10 to 40 [g / g].
Item 5.
The crystal nucleating agent is selected from the group consisting of 1,3: 2,4-bis-O-benzylidene-D-glucitol, 1,3: 2,4-bis-O- (4-methylbenzylidene) -D-sorbitol Item 5. The water-absorbent resin composition according to any one of Items 1, 2, 3, 3a, 3b, 3c or 4, which is at least one sorbitol-based nucleating agent.

  The water-absorbent resin composition of the present invention is superior in initial wettability and processing characteristics as compared with conventional water-absorbent resin compositions. This is because, since the water-absorbent resin composition of the present invention contains a crystal nucleating agent, the crystal growth is suppressed when the thermoplastic resin is crystallized at the time of melting and cooling, and the crystal becomes smaller. It is considered that the compatibility between the water-absorbing polyalkylene oxide-modified product and the thermoplastic resin is improved because crystallization is not hindered when the modified product is melted and cooled, and the crystal grows.

Measurement results of melt viscosities of the water-absorbent polyalkylene oxide modified product obtained in Production Example 1, the water-absorbent resin composition obtained in Example 1, the water-absorbent resin composition obtained in Comparative Example 1, and the polypropylene resins are shown. It is a graph to show. It is a photograph which shows the evaluation result of the initial wettability immediately after water dripping in the water absorbing resin composition obtained in Example 1. It is a photograph which shows the evaluation result of the initial wettability after 1 minute of water dripping in the water absorbing resin composition obtained in Example 1. It is a photograph which shows the evaluation result of the initial wettability immediately after water dripping in the water-absorbent resin composition obtained in Comparative Example 1. It is a photograph which shows the evaluation result of the initial wettability 60 minutes after the water dripping in the water absorbing resin composition obtained in Comparative Example 1.

  The water absorbent resin composition of the present invention comprises a thermoplastic resin, a water absorbent polyalkylene oxide modified product, an ethylene (meth) acrylic acid copolymer, and a crystal nucleating agent. More specifically, 10 to 50 parts by mass of a water-absorbing polyalkylene oxide modified product, 10 to 80 parts by mass of an ethylene (meth) acrylic acid copolymer, and 0.1 to 1 of a crystal nucleating agent with respect to 100 parts by mass of a thermoplastic resin. 0.0 part by mass.

The thermoplastic resin used in the water-absorbent resin composition according to the present invention is not particularly limited, but is particularly preferably used because the polyolefin resin is inexpensive, has a wide variety of structures and physical properties, and is highly recyclable. It is done. As the polyolefin resin, for example, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, and copolymers thereof (for example, ethylene-propylene copolymer) are preferable, and polyethylene and polypropylene are preferable. More preferably, polypropylene is more preferable. As the polypropylene, polypropylene having a melt flow rate (MFR) of 1,000 to 2,000 g / 10 minutes is more preferable, and polypropylene having a melt flow rate of 1,000 to 1,500 g / 10 minutes is more preferable. In addition, a polypropylene having a melt viscosity of 20 to 30 [Pa · s] at a shear rate of 200 [cm ⁻¹ ] is preferable. As the polyethylene, polyethylene having a melt flow rate of 5 to 15 g / 10 min is preferable. Further, a polypropylene having a melt viscosity of 200 to 400 [Pa · s] at a shear rate of 200 [cm ⁻¹ ] is preferable. For the measurement of the melt flow rate, the test machine uses an extrusion plastometer defined in JIS K6760, and the measurement method uses the method defined in JIS K7210.

  In addition, a thermoplastic resin (preferably polyolefin resin) can be used individually by 1 type or in combination of 2 or more types.

  As the water-absorbing polyalkylene oxide-modified product used in the water-absorbing resin composition according to the present invention, for example, a water-absorbing polyalkylene oxide-modified product obtained by reacting a polyalkylene oxide compound, a diol compound and a diisocyanate compound is preferable. . Such a modified polyalkylene oxide has better compatibility with thermoplastic resins than water-soluble resins such as polyalkylene oxide.

  Examples of the polyalkylene oxide compound include polyethylene oxide, polypropylene oxide, polybutylene oxide, ethylene oxide / propylene oxide copolymer, ethylene oxide / butylene oxide copolymer, propylene oxide / butylene oxide copolymer, and ethylene oxide / propylene oxide / butylene. An oxide copolymer etc. can be illustrated. Among these, polyethylene oxide, polypropylene oxide, and ethylene oxide / propylene oxide copolymer are preferable. A polyalkylene oxide compound can be used individually by 1 type or in combination of 2 or more types. Here, “/” is a symbol used to indicate a copolymer of each oxide. For example, an ethylene oxide / propylene oxide copolymer represents a copolymer of ethylene oxide and propylene oxide.

  Moreover, as said polyalkylene oxide compound, the polyalkylene oxide compound which has 90 mass% or more of ethylene oxide groups is preferable, and the polyalkylene oxide compound which has 95 mass% or more of ethylene oxide groups is more preferable. When the ethylene oxide group is 90% by mass or more, the initial wettability of the obtained water absorbent resin composition is further improved, which is preferable.

  The polyalkylene oxide compound is preferably a polyalkylene oxide compound having a number average molecular weight of 5,000 to 50,000, and more preferably a polyalkylene oxide compound having a number average molecular weight of 10,000 to 30,000. When a polyalkylene oxide compound having a number average molecular weight of 5,000 or more is used, the water absorbing ability of the resulting water absorbent resin composition can be further increased, which is preferable. Further, when a polyalkylene oxide compound having a number average molecular weight of 50,000 or less is used, the melt viscosity of the resulting water-absorbing polyalkylene oxide modified product does not become too high, and the compatibility with the thermoplastic resin becomes even better. It is preferable because the initial wettability is good. These polyalkylene oxide compounds can be used alone or in combination of two or more.

  Examples of the diol compound include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,3-butanediol, 2,3-butanediol, and 1,4-butanediol. 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol and the like. Among these diol compounds, ethylene glycol and 1,4-butanediol are from the viewpoint of excellent water absorption ability of the resulting water-absorbing polyalkylene oxide modified product, from the viewpoint of controlling the elution of water-soluble components, and from the viewpoint of excellent stability. Preferably used. These diol compounds may be used alone or in combination of two or more.

  The use ratio of the diol compound is preferably 0.8 to 2.5 mol, more preferably 1.0 to 2.0 mol, with respect to 1 mol of the polyalkylene oxide compound. When the usage ratio of the diol compound is 0.8 mol or more, the water absorbing ability of the water absorbent resin composition containing the resulting water absorbent polyalkylene oxide-modified product can be preferably improved. Moreover, when the usage-amount of a diol compound is 2.5 mol or less, the initial wettability of the water-absorbing resin composition containing the water-absorbing polyalkylene oxide modified product obtained can be preferably improved. The number of moles of the polyalkylene oxide compound can be determined by dividing its mass by the number average molecular weight.

  The diisocyanate compound is not particularly limited as long as it is a compound having two isocyanate groups (—NCO) in the same molecule. For example, 4,4′-diphenylmethane diisocyanate (MDI), 1,6-hexamethylene diisocyanate ( HDI), dicyclohexylmethane-4,4′-diisocyanate (HMDI), 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate (IPDI), 1,8-dimethylbenzool-2,4 -Diisocyanate, 2,4-tolylene diisocyanate (TDI), etc. are mentioned. Among these diisocyanate compounds, dicyclohexylmethane-4,4′-diisocyanate (HMDI) and 1 are used from the viewpoints of compatibility with thermoplastic resins, control of elution of water-soluble components, and excellent stability. , 6-hexamethylene diisocyanate (HDI) is preferably used. These diisocyanate compounds may be used alone or in combination of two or more.

  The ratio of each of the polyalkylene oxide compound, diol compound, and diisocyanate compound used is the ratio of the number of moles of isocyanate groups of the diisocyanate compound to the total number of moles of terminal hydroxyl groups of the polyalkylene oxide compound and hydroxyl groups of the diol compound [R value = (-NCO group / -OH group)] is preferably determined to be in the range of 0.7 to 1.2, more preferably 0.8 to 1.05. When R value is 0.7 or more, the water absorbing ability of the water absorbent resin composition containing the resulting water absorbent polyalkylene oxide modified product can be preferably improved. Moreover, when R value is 1.2 or less, the melt viscosity of the water-absorbing polyalkylene oxide modified product to be obtained does not become too high, the compatibility with the thermoplastic resin becomes good, and the initial wettability can be preferably improved. The number of moles of the polyalkylene oxide compound can be determined by dividing its mass by the number average molecular weight, and the number of moles of the terminal hydroxyl group of the polyalkylene oxide compound is equal to twice this.

As a method of reacting the polyalkylene oxide compound, the diol compound, and the diisocyanate compound, a known method can be used. For example, a method in which these are dissolved or dispersed in a reaction solvent such as toluene, xylene, or dimethylformamide; a method in which both are uniformly mixed in a powder or solid state, and then heated to a predetermined temperature to react. Is mentioned. From the viewpoint of industrial implementation, a method in which each raw material is continuously supplied in a molten state and mixed and reacted in a multi-screw extruder is preferable. In this case, the reaction temperature is preferably 70 to 210 ° C.

  Further, when producing a modified water-absorbing polyalkylene oxide, a catalyst may be added to the reaction system from the viewpoint of promoting the reaction. For example, an appropriate amount of triethylamine, triethanolamine, dibutyltin dilaurate, dioctyltin dilaurate, tin 2-ethylhexanoate, triethylenediamine, or the like can be added as a catalyst.

  By such a method, a polyalkylene oxide compound, a diol compound, and a diisocyanate compound can be reacted to obtain a modified water-absorbing polyalkylene oxide. According to such a method, the polyalkylene oxide-modified product is usually obtained in the form of, for example, a pellet, a sheet, or a film. These may be finely pulverized by a pulverizer or the like, and can be easily dissolved in water by pulverization. Although it does not specifically limit as a grinder, For example, an atomizer, a pin mill, a jet mill, a pulverizer etc. are mentioned as a grinder suitably used for a fine grinding. In addition, the water-absorbing polyalkylene oxide-modified product can be used alone or in combination of two or more.

In the present specification, the melt viscosity of the water absorbent resin composition according to the present invention, and the thermoplastic resin, water absorbent polyalkylene oxide modified product, and ethylene (meth) acrylic acid copolymer used in the resin composition are: It is a value measured by continuously changing the shear rate from 50 to 3000 [cm ⁻¹ ] with a capillary rheometer (measurement conditions: using a die having a diameter of 1 mm and a length of 10 mm at 190 ° C.). In particular, when the water-absorbent resin composition according to the present invention is used for general extruder processing, a shearing force of about 200 [cm ⁻¹ ] is usually applied in general, so The measurement value at a shear rate of 200 [cm ⁻¹ ] is preferably used as an index.

For the water-absorbing polyalkylene oxide-modified product, the melt viscosity at a shear rate of 200 [cm ⁻¹ ] is preferably 100 to 1000 [Pa · s], and more preferably 150 to 500 [Pa · s]. preferable. When the said melt viscosity is 100 [Pa * s] or more, the water absorption ability of the water-absorbent resin composition obtained can improve preferably. When the melt viscosity is 1000 [Pa · s] or less, the compatibility between the water-absorbing polyalkylene oxide-modified product and the thermoplastic resin is preferably improved, and the initial wettability of the resulting water-absorbing resin composition can also be preferably improved. .

  Moreover, the water absorbing ability of the water-absorbing polyalkylene oxide-modified product used in the water-absorbing resin composition according to the present invention is preferably 10 to 40 [g / g], more preferably 15 to 35 [g / g]. It is. When the water-absorbing ability of the water-absorbing polyalkylene oxide-modified product is 10 [g / g] or more, the water-absorbing ability of the resulting water-absorbing resin composition can be preferably improved. When the water-absorbing ability of the water-absorbing polyalkylene oxide-modified product is 40 [g / g] or less, the initial wettability of the water-absorbing resin composition can be improved. In addition, the water absorption ability of the water-absorbing polyalkylene oxide-modified product in the present invention is a value measured by the following method. That is, after weighing (A [g]) about 1 [g] of the water-absorbing polyalkylene oxide-modified product, this was added to 100 [mL] ion-exchanged water, and at room temperature (22 ° C.), After stirring and immersing for 24 hours to absorb water and preparing a gel, the gel is filtered through a wire mesh of 200 mesh (pore diameter: 75 μm), its mass (B [g]) is measured, and the value calculated by the following formula is used. is there.

  Water absorption capacity [g / g] = B / A

  The water absorption capacity of the water absorbent resin composition according to the present invention described below is a value measured in the same manner except that the water absorbent resin composition is used in place of the modified water absorbent polyalkylene oxide in the method. .

  The mixing ratio of the water-absorbing polyalkylene oxide-modified product is 10 parts by mass or more, preferably 15 parts by mass or more with respect to 100 parts by mass of the thermoplastic resin. The mixing ratio of the water-absorbing polyalkylene oxide-modified product is 50 parts by mass or less, preferably 30 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. That is, the mixing ratio of the water-absorbing polyalkylene oxide-modified product is 10 to 50 parts by mass, particularly preferably 15 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

  When the mixing ratio of the water-absorbing polyalkylene oxide-modified product is less than 10 parts by mass with respect to 100 parts by mass of the thermoplastic resin, the initial wettability of the resulting water-absorbing resin composition is deteriorated. Moreover, when the mixing ratio of the water-absorbing polyalkylene oxide-modified product exceeds 50 parts by mass with respect to 100 parts by mass of the thermoplastic resin, gel detachment is likely to occur. In this case, the detachment of the gel is likely to occur because the melt viscosity of the water absorbent resin composition becomes too high, and the compatibility between the water absorbent polyalkylene oxide modified product and the thermoplastic resin becomes poor. This is probably because the water-absorbing polyalkylene oxide-modified product in the product has a low dispersibility, and is dispersed as a large lump and easily peels off from the composition when the water is absorbed and the portion gels.

  In the present invention, in order to improve the compatibility between the modified water-absorbing polyalkylene oxide and the thermoplastic resin, an ethylene (meth) acrylic acid copolymer (that is, an ethylene acrylic acid copolymer and / or ethylene methacrylic acid) is used. Copolymer).

  The mixing ratio of the ethylene (meth) acrylic acid copolymer is 10 parts by mass or more, preferably 15 parts by mass or more with respect to 100 parts by mass of the thermoplastic resin. The mixing ratio of the ethylene (meth) acrylic acid copolymer is 80 parts by mass or less, preferably 50 parts by mass or less, with respect to 100 parts by mass of the thermoplastic resin. That is, the mixing ratio of the ethylene (meth) acrylic acid copolymer is 10 to 80 parts by mass, preferably 15 to 50 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

  When the mixing ratio of the ethylene (meth) acrylic acid copolymer is less than 10 parts by mass with respect to 100 parts by mass of the thermoplastic resin, the dispersibility of the water-absorbing polyalkylene oxide modified product is poor in the resulting water-absorbent resin composition. This is not preferable because the water absorption capacity is lowered. Moreover, when the mixing ratio of the ethylene (meth) acrylic acid copolymer exceeds 80 parts by mass with respect to 100 parts by mass of the thermoplastic resin, the wettability of the resulting water-absorbent resin composition is unfavorable.

The ethylene (meth) acrylic acid copolymer preferably has a melt viscosity of 20 to 100 [Pa · s] at a shear rate of 200 [cm ⁻¹ ], and is preferably 30 to 70 [Pa · s]. It is more preferable.

  As the crystal nucleating agent (nucleating agent) used in the present invention, known ones can be used. For example, commonly used sorbitol nucleating agents, organophosphate compounds, quinacridone, cyanine blue, talc, and the like can be preferably used. From the viewpoint of ease of handling and ease of melting, it is particularly preferable to use a sorbitol nucleating agent. More specifically, for example, 1,3: 2,4-bis-O-benzylidene-D-glucitol or 1 , 3: 2,4-bis-O- (4-methylbenzylidene) -D-sorbitol and the like are optimally used. The structural formulas of these compounds are as follows.

<1,3: 2,4-bis-O-benzylidene-D-glucitol (dibenzylidene sorbitol)>

<1,3: 2,4-bis-O- (4-methylbenzylidene) -D-sorbitol>

  The addition amount of the crystal nucleating agent is 0.1 parts by mass or more, preferably 0.15 parts by mass or more with respect to 100 parts by mass of the thermoplastic resin. The addition amount of the crystal nucleating agent is 1.0 part by mass or less, preferably 0.8 part by mass or less with respect to 100 parts by mass of the thermoplastic resin. That is, the addition ratio of the crystal nucleating agent is 0.1 to 1.0 part by mass, and particularly preferably 0.15 to 0.8 part by mass with respect to 100 parts by mass of the water-absorbing polyalkylene oxide-modified product. Part.

  When the addition amount of the crystal nucleating agent is less than 0.1 parts by mass with respect to 100 parts by mass of the thermoplastic resin, the effect of improving wettability is not recognized, which is not preferable. Moreover, when the mixing ratio of the crystal nucleating agent exceeds 1 part by mass, the odor of the crystal nucleating agent tends to remain, such being undesirable.

  In addition, a crystal nucleating agent can be used individually by 1 type or in combination of 2 or more types.

  As a method for producing the water absorbent resin composition according to the present invention, for example, the thermoplastic resin, the water absorbent polyalkylene oxide modified product, the ethylene (meth) acrylic acid copolymer, and the crystal nucleating agent are mixed with a Henschel mixer, Examples thereof include a method in which the components are mixed using a blender such as a blender and then melt-mixed, or a method in which these components are supplied to a kneader, a roll, an extruder, etc. with a quantitative feeder or the like and melt-mixed.

  As an apparatus for performing melt mixing, a twin-screw extruder is preferably used from the viewpoint of excellent mixing of the above components.

  After melt mixing, it may be formed into a desired shape such as a pellet, sheet, rod, or fiber by injection molding or extrusion.

The obtained water-absorbent resin composition preferably has a melt viscosity at a shear rate of 200 [cm ⁻¹ ] of 10 to 100 [Pa · s], preferably 20 to 80 [Pa · s]. More preferably, it is 30-60 [Pa * s]. The melt viscosity of the water-absorbent resin composition is the melt viscosity of the thermoplastic resin (preferably polyolefin resin) used in the water-absorbent resin composition (measured value at a shear rate of 200 [cm ⁻¹ ]). Is preferably 1.5 to 4 times, more preferably 1.8 to 3 times, and even more preferably 2 to 2.5 times.

  When the melt viscosity of the water-absorbent resin composition is 10 [Pa · s] or more, the water-absorbing performance of the resulting water-absorbent resin composition can be further improved. Moreover, when the said melt viscosity is 100 [Pa * s] or less, wettability is more preferable.

  Moreover, the water absorption capacity of the water absorbent resin composition is preferably 1 to 8 [g / g], more preferably 2 to 5 [g / g].

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[Evaluation method]
The water-absorbing ability, initial wettability, and melt viscosity of the water-absorbing polyalkylene oxide-modified product described in each production example described below and the water-absorbing resin composition described in each example were measured and evaluated according to the following methods. did.

  As for water absorption ability and initial wettability, after 10 g of pellets of a polyalkylene oxide modified product or a water absorbent resin composition were immersed in 100 ml of liquid nitrogen for 5 minutes and then used in a pulverizer to form a powder having an average particle size of 100 μm The measurement was performed on the powder.

(1) Water-absorbing capacity After weighing (A [g]) a pulverized product of polyalkylene oxide-modified product or water-absorbing resin composition of about 1 [g], it was poured into 100 [mL] ion-exchange water at room temperature (22 (° C.) for 24 hours with stirring and immersion. Thereafter, the gel was filtered with a wire mesh of 200 mesh (pore diameter: 75 μm), the mass (B [g]) was measured, and the water absorption capacity was calculated according to the following formula. In addition, regarding the water-absorbing resin composition, it can be said that the water-absorbing performance is particularly excellent if the water-absorbing ability is in the range of 2 to 5 [g / g].
Water absorption capacity [g / g] = B / A

(2) Initial wettability A 0.2 [g] pulverized product of the water-absorbent resin composition was placed on a filter paper, and 0.1 ml of colored water was dropped from above to observe changes in water droplets over time. The results were evaluated as follows.

○: Water permeates within 3 minutes and the lower filter paper gets wet △: Water penetrates after 30 minutes and the lower filter paper gets wet ×: Water drops remain on the pulverized product and do not penetrate even after the passage of 1 hour .

(3) Melt viscosity Melt viscosity measurement object (water-absorbing resin composition, thermoplastic resin, water-absorbing polyalkylene oxide modified product, or ethylene (meth) acrylic acid copolymer) 30 g is twin capillary rheometer (manufactured by Chiast Corp.) It was measured under the following conditions with Smart Leo 2000), and the melt viscosity at 200 [cm ⁻¹ ] was read. In addition, regarding a water-absorbent resin composition, if the melt viscosity is 100 Pa · s or less, it can be said that the processing characteristics are excellent.

Temperature: 190 ° C
Die diameter: 1mm
Die length: 10mm
Shear rate: 50 to 3,000 [cm ⁻¹ ]

  In addition, the water-absorbing polyalkylene oxide modified product obtained in Production Example 1 below, the water-absorbing resin composition obtained in Example 1, the water-absorbing resin composition obtained in Comparative Example 1, and polypropylene (melt flow rate [MFR]) = 1100 g / 10 min) The measurement results of the melt viscosity of each resin are collectively shown in FIG.

Production Example 1 Production of Modified Water-Absorbing Polyalkylene Oxide In a storage tank A equipped with a stirrer kept at 80 ° C., 100 parts by mass of fully dehydrated polyethylene oxide having a number average molecular weight of 20,000, 1,4-butanediol 0.9 parts by mass and 0.1 parts by mass of dioctyltin dilaurate were added and stirred under a nitrogen gas atmosphere to obtain a uniform mixture. Separately, dicyclohexylmethane-4,4′-diisocyanate was charged into storage tank B kept at 30 ° C. and stored in a nitrogen gas atmosphere.

  Using a metering pump, the mixture in storage tank A at a rate of 500 [g / min] and the dicyclohexylmethane-4,4′-diisocyanate in storage tank B at a rate of 19.4 [g / min] Continuously supplied to a twin-screw extruder set at 110 to 140 ° C. (R value (-NCO group / -OH group) = 1.0), mixed and reacted in the extruder, and from the extruder outlet The strand was taken out and pelletized with a pelletizer to obtain a modified water-absorbing polyalkylene oxide. The water absorption capacity was 25 [g / g], and the melt viscosity was 450 [Pa · s].

Production Example 2 Production of modified water-absorbing polyalkylene oxide Heated ethylene oxide / propylene oxide (mass ratio: 90/10) copolymer having a number average molecular weight of 15,000 to 40 ° C. at a rate of 250 [g / min]. The ethylene glycol thus obtained was supplied to a 40 mmφ single screw extruder (L / D = 40, set temperature: 90 ° C.) at a speed of 2.1 [g / min], and both were melt mixed.

  A mixture obtained from the discharge port (discharged in a uniform molten state and analyzed by LC and confirmed to be mixed at a charging ratio) was mixed with a 30 mmφ twin-screw extruder (L / D = 41. 5) was continuously supplied to the hopper port (set temperature: 80 ° C.). At the same time, dioctyltin dilaurate was supplied to the hopper port of the twin-screw extruder at a rate of 0.5 [g / min].

  Separately, dicyclohexylmethane-4,4′-diisocyanate adjusted to 30 ° C. at a speed of 12.4 [g / min] is placed on the screw barrel portion located downstream of the hopper port of the twin-screw extruder. (R value (-NCO group / -OH group) = 0.95) and continuously reacted in a nitrogen atmosphere (set temperature: 180 ° C.). The strand obtained from the twin-screw extruder outlet was cooled and then pelletized with a pelletizer to obtain a modified water-absorbing polyalkylene oxide. The water absorption capacity was 20 [g / g], and the melt viscosity was 150 [Pa · s].

Example 1
100 parts by mass of polypropylene (abbreviation: PP, HP461X manufactured by Poy Mirae, MFR = 1100 g / 10 min, melt viscosity 25 [Pa · s]), ethylene acrylic acid copolymer (abbreviation: EAA, Primacol 5980 manufactured by Dow Chemical) MFR = 300 g / 10 min, melt viscosity 50 [Pa · s]) 15 parts by mass, modified water-absorbing polyalkylene oxide obtained in the same manner as in Production Example 1, and 1: 3 as a crystal nucleating agent , 4-Bis-O-benzylidene-D-glucitol (abbreviation: BGS, Nipponol Chemical Co., Ltd., Gelol D) 0.30 parts by mass was mixed with a Henschel mixer, and then a 28 mmφ twin screw extruder (L / D = 40) at 15 (Kg / Hr) to obtain water-absorbing resin composition pellets. Table 1 shows the composition ratio of the resin composition and the measurement results. FIG. 2 shows the evaluation results of the initial wettability immediately after dripping water, and FIG.

Example 2
100 parts by mass of polypropylene (abbreviation: PP, HP461X manufactured by Poy Mirae, MFR = 1100 g / 10 min, melt viscosity 25 [Pa · s]), ethylene acrylic acid copolymer (abbreviation: EAA, Primacol 5980 manufactured by Dow Chemical) MFR = 300 g / 10 min, melt viscosity 50 [Pa · s]) 40 parts by mass, modified water-absorbing polyalkylene oxide obtained in the same manner as in Production Example 2, and 1: 3 as a crystal nucleating agent , 4-bis-O- (4-methylbenzylidene) -D-sorbitol (abbreviation: BMS, Nippon Nippon Chemical Co., Ltd., Gelol MD) 0.8 parts by mass was mixed with a Henschel mixer, and then 28 mmφ 2 set at 170 ° C. It supplied to the screw extruder (L / D = 40) at 15 (kg / hr), and the water absorbent resin composition pellet was obtained. Table 1 shows the composition ratio of the resin composition and the measurement results.

Example 3
100 parts by mass of polyethylene (abbreviation: PE, Chisso UP Polyethylene J110K, MFR = 10 g / 10 min, melt viscosity 300 [Pa · s]), ethylene methacrylic acid copolymer (abbreviation: EMA, High Milan manufactured by Mitsui DuPont Polychemical Co., Ltd.) 1605, MFR = 2.8 g / 10 min, melt viscosity 50 [Pa · s]) 25 parts by mass, 15 parts by mass of the water-absorbing polyalkylene oxide modified product obtained in the same manner as in Production Example 1, crystal nucleating agent BGS After mixing 0.5 parts by mass (Shin Nippon Rika Co., Ltd. Gelol D) with a Henschel mixer, it is fed to a 28 mmφ twin screw extruder (L / D = 40) set at 160 ° C. at 20 (Kg / Hr), Water-absorbent resin composition pellets were obtained. Table 1 shows the composition ratio of the resin composition and the measurement results.

Comparative Example 1
A water-absorbent resin composition was obtained in the same manner as in Example 1 except that the mixing ratio of the crystal nucleating agent BGS (Gerol D, manufactured by Nippon Nippon Chemical Co., Ltd.) was changed to 0.05 parts by mass. Table 1 shows the composition ratio of the resin composition and the measurement results. FIG. 4 shows the evaluation results of the initial wettability immediately after water dripping, and FIG. 5 shows the initial wettability after 60 minutes of water dripping.

Comparative Example 2
Example 2 except that the mixing ratio of the ethylene acrylic acid copolymer (abbreviation: EAA, Primacol 5980, MFR = 300 g / 10 min, melt viscosity 50 [Pa · s]) manufactured by Dow Chemical Company was changed to 150 parts by mass. In the same manner, a water-absorbent resin composition was obtained. Table 1 shows the composition ratio of the resin composition and the measurement results.

Comparative Example 3
A water absorbent resin composition was obtained in the same manner as in Example 3 except that the mixing ratio of the water absorbent polyalkylene oxide modified product was changed to 60 parts by mass. Table 1 shows the composition ratio of the resin composition and the measurement results.

  As is apparent from the results shown in Table 1 and FIGS. 2 to 5, 10 to 80 parts by mass of an ethylene (meth) acrylic acid copolymer and a water-absorbing polyalkylene oxide-modified product with respect to 100 parts by mass of the thermoplastic resin. The water-absorbent resin composition of the present invention containing 10 to 50 parts by mass and crystal nucleating agent 0.1 to 1.0 parts by mass is excellent in initial wettability and processing characteristics represented by melt viscosity.

  Since the water-absorbent resin composition according to the present invention is excellent in processability, it can be easily processed into sheets, films, fibers and the like. The obtained processed product is excellent in initial water absorption rate and wettability, so various products such as separators for batteries, electronic parts, protective equipment for electronic devices, water absorbent sheets for cosmetics, water and aqueous fluid composition Goods such as wet tissues, disposable towels, water-containing sheets (for example, decorative sheets), and clothing (for example, clothing using the moisture absorption and release properties of water-absorbing polyalkylene oxide-modified products) Can be widely used.

Claims (5)

(A) 100 parts by mass of a thermoplastic resin,
(B) 10 to 50 parts by mass of a water-absorbing polyalkylene oxide modified product,
(C) ethylene (meth) acrylic acid copolymer 10-80 parts by mass, and (D) crystal nucleating agent 0.1-1.0 part by mass,
A water-absorbent resin composition comprising: The water absorbent resin composition according to claim 1, wherein the thermoplastic resin is at least one polyolefin resin selected from the group consisting of polyethylene and polypropylene. The water absorbent resin composition according to claim 1 or 2, wherein the water absorbent polyalkylene oxide modified product is a water absorbent polyalkylene oxide modified product obtained by reacting a polyalkylene oxide compound, a diol compound and a diisocyanate compound. The water-absorbing resin composition according to any one of claims 1 to 3, wherein the water-absorbing polyalkylene oxide-modified product has a water absorption capacity of 10 to 40 [g / g]. The crystal nucleating agent is selected from the group consisting of 1,3: 2,4-bis-O-benzylidene-D-glucitol, 1,3: 2,4-bis-O- (4-methylbenzylidene) -D-sorbitol The water-absorbent resin composition according to any one of claims 1 to 4, which is at least one sorbitol-based nucleating agent.

Images