JP2891803B2 - Swellable structure and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet laid in a food container for absorbing sap and dew water from foods, and a wrapping sheet used for absorbing dew water to maintain freshness of fruits and vegetables. A sheet for absorbing dew condensation by attaching it to the ceiling, wall, or inner wall of a container of a building, or as a source of water vapor by absorbing water in advance when heating food with a microwave oven It can be used for various purposes such as packaging, absorbing moisture for freshness of meat and fish, and is formed into a sheet that absorbs moisture and swells while retaining its original form, and forms other than sheets. And a method for producing the same.

[0002]

2. Description of the Related Art Fresh food products are displayed in a film tray pack system, which is placed on a tray made of a material such as expanded polystyrene and covered with a transparent film. However, blood juice from meat fish or the like impairs the appearance. It has been practiced to lay a sheet that absorbs moisture between the tray and the food while holding the sheet. In addition, a swellable sheet is used to absorb dew water such as fruits and vegetables for dehumidifying cooked rice and preserving various foods. Further, it is desired that a sheet to be attached to a ceiling or a wall for absorbing dew water in a room is suitable for interior decoration. Conventionally, as a swellable sheet used for these applications, a sheet-shaped water absorbent obtained by applying a water-absorbent resin powder to a nonwoven fabric or a plastic sheet together with a binder, or a dry nonwoven fabric comprising a highly water-absorbent fiber is known. However, in the former case, the swollen gel particles easily fall off and the coating amount cannot be increased, or the swelling property is hindered by the binder, and the water absorption amount cannot be increased. limited.

[0003] As a proposed absorbent sheet for food packaging, a laminated material of a gas-permeable foamed molded article of polyethylene and a sheet of cellulose fiber (Japanese Utility Model Publication No. 54-534) has been proposed.
No. 9) has a small water absorption and a small holding power of the absorbed liquid. A sheet (Japanese Utility Model Application Laid-open No. 58-49779) in which one or both sides are made of a gas-permeable layer such as paper, cloth, or perforated sheet, and a water-absorbent resin is laminated as an intermediate layer between the sheets requires holding and joining with an adhesive. Difficult to manufacture,
Further, an absorbent sheet (Japanese Utility Model Laid-Open No. 1-163123) in which a protective sheet is integrated on both sides of a water-absorbent nonwoven sheet is a porous protective sheet on both sides of a water-absorbent nonwoven fabric made of an acrylonitrile-acrylate copolymer or the like. It is necessary to laminate and bond a film made of a thermoplastic resin and a non-woven fabric formed of fibers of the thermoplastic resin using an adhesive or a thermocompression bonding as a protective sheet.

[0004]

The above-mentioned conventional swellable sheet has insufficient swelling performance, avoids contact with food, protects the water-absorbent resin and water-absorbent nonwoven fabric of the water-absorbing layer, and protects the surface. It requires a surface layer to prevent slimming and is generally limited to sheet form.

[0005] When a polyfunctional agent such as epichlorohydrin is added to a water-soluble salt of fibrous carboxymethylcellulose (hereinafter, abbreviated as "fibrous CMC" as necessary) to form crosslinks, The phenomenon that water solubility is lost and a swollen gel body is formed is known, and a water-absorbing fibrous structure based on this phenomenon has been proposed (JP-A-54-5).
No. 2189). However, in this case, the strength of the swollen sheet is low, so that the sheet cannot be used for such applications as it is. In addition, the fibrous CMC is cross-linked with a polyfunctional resin such as a polyamide polyamine epichlorohydrin-based resin, and after papermaking, is alkali-treated to form a water-soluble salt of the fibrous CMC, thereby having a certain degree of wet strength. Although it can be made, since the pH of the paper surface becomes alkaline due to the last alkali coating, it is not suitable for applications directly in contact with food or human body without a protective layer,
Further, since the absorbed water is mainly taken into the swollen gel of the water-soluble salt of fibrous CMC, slimming of the surface is unavoidable, and a surface layer is required to prevent slimming.

The present invention is a neutral swellable structure having excellent liquid absorption and wet strength, which does not require a surface layer.
The present invention has been made to provide a structure that can be used in a single layer of a swollen body and that can be formed into various forms, not limited to a sheet form.

The present invention provides a swellable structure comprising a fibrous carboxymethylcellulose salt, wherein the repeating unit has at least one selected from primary nitrogen, secondary nitrogen, tertiary nitrogen and quaternary nitrogen atoms. Containing, other than these nitrogen atoms, a cationic water-soluble polymer substantially free of a functional group generating a cross-linking bond,
Ri Na and polyelectrolyte complex is formed on at least a portion of the salt of the fibrous carboxymethyl cellulose, absorbed
Swellable structure water is characterized Rukoto cormorants discharged by an external force.

[0008] Here, the primary nitrogen atom is a nitrogen atom having a bond bonded to one carbon atom and two hydrogen atoms, and is an amino group or what is conventionally called a primary amino group. . Compounds containing a primary nitrogen atom are primary amines. The secondary nitrogen atom is a nitrogen atom having a bond bonded to two carbon atoms and one hydrogen atom, and may be conventionally called a secondary amino group. Compounds containing a secondary nitrogen atom are secondary amines. A tertiary nitrogen atom is a nitrogen atom having a bond bonded to three carbon atoms, and may be conventionally called a tertiary amino group. Compounds containing a tertiary nitrogen atom are tertiary amines. The quaternary nitrogen atom is a nitrogen atom having a bond bonded to four carbon atoms, and forms a quaternary ammonium salt by ionic bond with an anion.

In the present invention, a polyamine resin, a polyethyleneimine, an ionene polymer, or a polyamine resin is used without using a polyfunctional agent or a polyfunctional resin for crosslinking a salt of fibrous CMC.
It is characterized in that a polyelectrolyte complex is formed on at least a part of the salt of fibrous CMC using another cationic polymer.

The cationic water-soluble polymer is a polymer compound having a basic group in the molecule and is a repeating compound having at least one selected from primary, secondary, tertiary and quaternary nitrogen atoms. It is a water-soluble polymer consisting of units. Examples of such a cationic water-soluble polymer include chitosan, a natural polymer compound, and a synthetic polymer includes a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom, 4
There are a polymer (1) having a quaternary nitrogen atom and a polymer (2) having a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom or a quaternary nitrogen atom in the main chain of the polymer.

One example of the polymer (1) having a primary, secondary, tertiary or quaternary nitrogen atom in the side chain of the polymer is as follows: (1-a) Primary, secondary, tertiary or quaternary A homopolymer of a monomer having a secondary nitrogen atom and a polymerizable group such as a vinyl group in addition thereto, that is, a homopolymer of the following monomers. N, N-dialkylvinylamine, vinyltrialkylammonium, N-alkylaminoalkyl acrylate, N-alkylaminoalkyl methacrylate, N
-Alkylaminoalkylacrylamide, N-alkylaminoalkylmethacrylamide, N, N-dialkylaminoalkylacrylate, N, N-dialkylaminoalkylmethacrylate, N, N-dialkylaminoalkylacrylamide, N, N-dialkylaminoalkylmeth Acrylamide, acryloyloxyalkyltrialkylammonium, methacryloyloxyalkyltrialkylammonium, acrylamidoalkyltrialkylammonium, methacrylamidoalkyltrialkylammonium, vinyloxyalkylamine, N-alkylvinyloxyalkylamine, N, N-dialkylvinyloxyalkyl Amine,
Monomers such as N, N, N-trialkylvinyloxyalkylammonium. In these monomers, the alkyl group has 1 to 4 carbon atoms, and an alkanol group may be introduced in place of the alkyl group.
An alkoxycarbonylalkylene group may be introduced instead of one alkyl group bonded to the nitrogen atom of the ammonium salt. A specific example of the homopolymer of the above monomer is poly (methacryloyloxyethyltrimethylammonium chloride).

Other examples of the polymer (1) having a primary, secondary, tertiary or quaternary nitrogen atom in the side chain of the polymer include: (1-b) primary, secondary, tertiary or quaternary A copolymer of a monomer having a graded nitrogen atom and another polymerizable group with another monomer, that is, a copolymer of the monomer described in (1-a) with another monomer. Other monomers include acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, alkyl acrylate, alkyl methacrylate, vinyl acetate, styrene,
α-methylstyrene, 4-vinylpyridine, 2-vinylpyridine and the like. One specific example of the copolymer is poly (3-acrylamido-3-methylbutyltrimethylammonium chloride-CO-acrylamide).

Still another example of the polymer (1) having a primary, secondary, tertiary or quaternary nitrogen atom in the side chain of the polymer is as follows: (1-c) A homopolymer such as polyacrylamide is modified by Mannich. Alternatively, some are cationized by a Hoffman decomposition reaction.

The polymer (2) having a primary, secondary, tertiary or quaternary nitrogen atom in the main chain of the polymer includes (2)
-A) ionene polymer, (2-b) polyethyleneimine, (2-c) polyamine resin in a narrow sense, (2-d) other condensation polymers.

(2-a) Ionene polymer is a polymer having an ionic amino group, especially a quaternary ammonium group in the main chain, and most of the nitrogen atoms are quaternized. 2-ai) Polyadduct of dihalo compound having halogen atoms at both ends of molecule and ditertiary amine having tertiary nitrogen atoms at both ends of molecule (general formula (I))

[0016]

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(In the above general formula (I), R is a group having 1 to 4 carbon atoms including a substituent such as a hydroxyl group, a hydroxymethyl group, a hydroxyethyl group, etc. Y represents a hydroxyl group, a hydroxymethyl group, a carbon number of 1 to 10 including a substituent such as an alkyl group of 1 to 3 carbon atoms (however, the carbon number of the substituent is not included) ) Alkylene group, arylene alkylene group (eg, ethylenephenethylene group, etc.)
Represents X represents a halogen atom. A is a methylene group,
Or hydroxyl group, hydroxymethyl group, carbon number 1
Represents a methylene group having a substituent such as an alkyl group of 3 to 3, and k and f are integers of 1 to 10. B is 2
Any of the valence groups.

[0018]

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M is a positive integer. ),

(2-a-ii) A polymerizable precursor (tertiary amine having chlorine groups at both ends of the molecule) formed by ring-opening addition of 2 moles of epichlorohydrin to 1 mole of the primary amine; With a tertiary amine having a tertiary nitrogen atom (general formula (II))

[0021]

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(In the general formula (II), R ¹ has 1 to 20 carbon atoms including those having a substituent such as a hydroxyl group, a hydroxymethyl group, a hydroxyethyl group. A), wherein R ² is
It represents an alkyl group having 1 to 6 carbon atoms (but not including the number of carbon atoms of the substituent) including those having a substituent such as a hydroxyl group, a hydroxymethyl group, and a hydroxyethyl group.
Y represents a hydroxyl group, a hydroxymethyl group, a carbon atom of 1
Represents an alkylene group having 1 to 10 carbon atoms (however, not including the carbon number of the substituent) and an arylenealkylene group (eg, an ethylene phenethylene group and the like), including those having a substituent such as an alkyl group of 1 to 3; m is a positive integer. ),

(2-a-iii) 1 mol of epichlorohydrin is added to 1 mol of secondary amine by ring-opening addition. A chlorine atom is provided at one molecular end and a tertiary nitrogen atom is provided at the other molecular end. Polymer obtained by polyaddition of a compound having the general formula (II
I))

[0024]

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(In the general formula (III), R ¹ and R ² each have 1 to 10 carbon atoms including those having a substituent such as a hydroxyl group, hydroxymethyl group, hydroxyethyl group, etc. R ¹ and R ² may be the same or different, and m is a positive integer.)

(2-b) Polyethyleneimine is a polymer formed by ring-opening polymerization of ethyleneimine,
It has primary, secondary and tertiary nitrogen atoms in the main chain branched from the main chain.

(2-c) Although the academic definition of the polyamine resin has not been established, in a narrow sense, for example, primary, secondary, and
And quaternary nitrogen atoms are defined as containing less than half of the total number of nitrogen atoms, and are distinguished from the above-mentioned ionene polymers in that they have less quaternary nitrogen atoms.

For example, (2-ci) primary amine 1
A polyamine (general formula (IV)), which is a polymer obtained by polycondensation of a compound obtained by ring-opening addition of one mole of epichlorohydrin to a mole thereof while suppressing the formation of quaternary nitrogen atoms. Equation (V)).

[0029]

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(In the above general formulas (IV) and (V), R represents 1 to 20 carbon atoms including those having a substituent such as a hydroxyl group, a hydroxymethyl group, a hydroxyethyl group, etc. Not including a number)
m is a positive integer. )

(2-c-ii) Polyamine resin which is a polycondensate of alkylenediamine and epichlorohydrin

[0032]

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(In the above general formula (VI), Y has 1 to 10 carbon atoms including those having a substituent such as a hydroxyl group, hydroxymethyl group, hydroxyethyl group, etc. ) Represents an alkylene group, and m is a positive integer.),

(2-c-iii) Polyamine resin which is a polycondensate of alkylenediamine and alkylenedihalide

[0035]

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(In the above general formula (VII), Y and Y 'each have 1 to 10 carbon atoms including those having a substituent such as a hydroxyl group, a hydroxymethyl group and a hydroxyethyl group. ), And m is a positive integer.).

(2-d) Other condensation polymers include (2-di) a polyamine polyamide which is a polycondensate of an alkylene polyamine and a dicarboxylic acid, for example, a polycondensate of diethylene triamine and adipic acid; d
-Ii) When epichlorohydrin and dimethylamine are further added to this polyamine polyamide, the chloro group of epichlorohydrin is added to the amide group of the polyamine polyamide to quaternize and epichlorohydrin is opened to dimethylamine. Cycloaddition results in a polymer having secondary, tertiary and quaternary nitrogen atoms in the main chain and tertiary nitrogen atoms in the side chains.

Further, in the above-mentioned chitosan, homopolymer, copolymer and modified products, a polymer obtained by quaternizing a primary, secondary or tertiary nitrogen atom with a quaternizing agent is also a cationic water-soluble polymer. It is. The quaternizing agent is capable of introducing an alkyl group or an alkoxycarbonylalkylene group into a primary, secondary, or tertiary nitrogen atom, and includes alkyl halides such as methyl chloride, ethyl chloride, and methyl bromide, dimethyl sulfate, and chlorosulfate. Methyl acetate and the like. The quaternization reaction may be carried out at the stage where the repeating unit is a monomer, followed by polymerization, or after polymerization, the repeating unit in the polymer may be subjected to quaternization by a polymer reaction.

The cationic water-soluble polymer used in the present invention has a highly reactive functional group capable of forming a cross-linking bond other than a primary, secondary, tertiary or quaternary nitrogen atom, for example, a glycidyl group, an aldehyde group, Carboxyl group, vinyl group, allyl group, N-methylol group, thiol group, isocyanate,
It is necessary that it does not substantially contain isothiocyanate or the like. This is because the cationic water-soluble polymer is a fibrous CM.
This is for preventing the formation of a crosslink of a covalent bond other than the formation of a polymer electrolyte complex on C. The term “substantially free” means that the covalent cross-linking is not included to such an extent that the formation of the polyelectrolyte complex is inhibited or reduced, and as a result, the water-absorbing swellable structure becomes slimy.

The cationic water-soluble polymer used in the present invention has a cation equivalent of 0.1 to 20 meq / g, preferably 1 to 15 meq / g, more preferably 2 to 15 at a pH of 3 to 9. -10 to 10 meq / g, and the (number) average molecular weight is 5,000 to 100,000, preferably 5,000 to 70,000, and more preferably 5,000.
~ 20,000.

The salt of fibrous CMC is a lithium salt, a sodium salt, a potassium salt, a calcium salt, a magnesium salt, an ammonium salt, or an amine salt such as methylamine and ethanolamine. The degree of etherification of the fibrous CMC is 0.1 to 1.0, preferably 0.3 to 0.8, more preferably 0.4 to 0.6, and the base saturation of the fibrous CMC salt ( The proportion of carboxyl groups that have become salts) is 50 to 100%, preferably 80 to 100%,
More preferably, it is 90 to 95%.

The amount of the cationic water-soluble polymer to be added to the salt of the fibrous CMC is within the range corresponding to the cation equivalent of 0.1 to 100% of the anion equivalent of the fibrous CMC. An appropriate amount is selected according to the type of the polymer. The addition of the cationic water-soluble polymer forms a polyelectrolyte complex in the fibrous CMC salt. The polymer electrolyte complex is a complex which is considered to be formed mainly through Coulomb force between a fibrous CMC salt having the opposite charge and a cationic polymer. Although the details of the structure are not clear, the cationic water-soluble polymer ionically cross-links between the molecules of the fibrous CMC or the fibrous CM.
A structure in which a cationic water-soluble polymer is close to the molecular chain of C may be considered.

The swellable structure according to the present invention comprises a dispersion obtained by dispersing a fibrous carboxymethylcellulose salt in water , a primary nitrogen atom, a secondary nitrogen atom, and a tertiary nitrogen atom. And a cation-type water-soluble polymer containing at least one type of repeating unit selected from quaternary nitrogen atoms and substantially free of a functional group capable of forming a cross-linking bond other than these nitrogen atoms. It can be produced by preparing a stock having at least a portion of a salt of carboxymethyl cellulose formed with a polyelectrolyte complex, dehydrating and shaping the stock.

Here, the dehydration and molding means not only the case where the sheet is formed by drying and forming the sheet by the ordinary papermaking technique, but also the step of dipping a convex-shaped wire mesh for molding into the raw material dispersion, Including the case where the inside of the wire mesh is depressurized to deposit fibers on the wire mesh, pressed, dried, and then the mold is removed, so as to be formed into various shapes by a so-called molding method.

In the production of the swellable structure of the present invention,
In addition to the above raw materials, wood pulp, non-wood pulp, dissolving pulp, semi-synthetic fiber for papermaking, synthetic fiber for papermaking, inorganic fiber for papermaking, etc. are used in order to reduce costs and improve papermaking properties.
You may mix | blend in the range of 25 weight% or less by weight. Further, a small amount of a wet paper strength imparting agent may be added.

[0046]

In the swellable structure according to the present invention, a primary,
At least a portion of the fibrous CMC salt forms a polyelectrolyte complex by a cationic water-soluble polymer substantially free of a functional group that forms a cross-linking bond other than a secondary, tertiary or quaternary nitrogen atom. The swollen structure has a high wet strength. This is considered to be because the fibrous CMCs are bonded to each other via the cationic water-soluble polymer, and the type of the bond is the COO 2 ^— group of the fibrous CMC and the quaternary cationic water-soluble polymer. Ionic bond with nitrogen atom, COO ^- group and 1
Amides formed by dehydration of primary or secondary nitrogen atoms (primary or secondary amino groups) in the drying process, and COOH groups remaining on the fibrous CMC even after the formation of the polymer electrolyte complex, these may be Acid anhydrides formed by dehydration in the drying process.

It is considered that the fibrous CMC salt swells and gels while maintaining the fibrous form, and retains water in a large number of voids between the fibers. When cross-linking is performed with a cationic polymer containing a highly reactive functional group such as a glycidyl group, cross-linking due to a covalent bond between fibrous CMC molecules is generated, and the generation of a polymer electrolyte complex is suppressed. Thus, while the absorbed water is mainly absorbed in the swollen gel of the fibrous CMC salt, in the swellable structure according to the present invention, the water is absorbed in the swollen gel of the fibrous CMC salt. In addition, it is held inside the void structure of the fiber. The water absorbed in the swollen gel of the fibrous CMC salt is not discharged even when an external force is applied, and when the amount of the absorbed water is large, it causes slimming. However, the water retained in the voids of the fiber is In other words, since it is taken into the pores of the sponge structure, even if it is held in a large amount, the structure surface does not feel slimy and is discharged by external force. Therefore, the swellable structure according to the present invention does not cause swelling on the surface of the swelled body despite having an absorption amount of 7 to 15 times its own weight. For this reason, the swellable structure of the present invention,
It does not require a surface layer for slimming, can be used as a single layer, and can be formed into various structures other than sheets. Further, since the absorbed water is discharged by an external force, it can be used repeatedly depending on the application.
Also, since alkali coating is not performed at the end of the manufacturing process,
It has a neutral pH and can be used in direct contact with food and the human body.

Further, in addition to producing a single-layer sheet by papermaking, a plurality of wet papers are produced from the same raw material by a paper machine having two or more nettings and are laminated to produce a sheet having a large basis weight. It is also possible to manufacture various types of laminated structures by laminating with sheets of different kinds of raw materials or laminating with a synthetic resin film.

[0049]

EXAMPLES Examples of the swellable structure according to the present invention will be described below. In each example, the water absorption of the swellable structure,
Wet tensile strength, degree of slimming in wet state, paper p
H was evaluated as follows.

<Amount of Water Absorption> A test piece of 10 cm × 12 cm was immersed in 1000 ml of tap water for 30 minutes, pulled up, suspended for 1 minute with one end thereof up, dropped the excess water, and then weighed. The water absorption was calculated by the following equation. Water absorption (g / g) = ｛(test specimen weight g after removal of excess water)
-(Test piece air dry weight g) {Test piece air dry weight g}

<Wet tensile strength> Width 15 mm, length 2
After a test piece of 00 mm was immersed in tap water at 20 ° C. for 30 minutes, excess water was wiped off with a filter paper, and the tensile strength was measured with a Shopper type tensile tester.

<Slimming in wet condition> 10cm × 12c
After immersing the test piece of m in 1000 ml of tap water for 3 minutes, the test piece was pulled up, and the feel of the test piece surface was organoleptically evaluated.

<PH on paper surface> A pH indicator solution was applied to the test piece, and the coloration was observed by comparing with a standard plate.

Example 1 A fibrous CMC Na salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 90%) was dispersed in water to give a 1.5% concentration dispersion. Prepared. A polyamine resin (trade name Sumirezu Resin FR-2P, manufactured by Sumitomo Chemical Co., Ltd., number average molecular weight 10,000), cation equivalent of 5.8 meq / g at pH 6, quaternized nitrogen atom and tertiary nitrogen atom Containment: Hereinafter, "FR"
-2P ") was added at a ratio of 2.0% by weight to the Na salt of the fibrous CMC, and stirred to prepare a paper stock. 70g /
to produce a sheet of m ^2.

With respect to the obtained swellable sheet, the water absorption,
The wet tensile strength and the sliminess in a wet state were evaluated, and the results are shown in Table 1. For comparison, the evaluation results of the tissue paper are also shown in Table 1 as comparative products. Table 1
As can be seen from the above, the product of the present invention based on Example 1 absorbed 12 times the amount of its own weight of tap water and had high wet strength even after absorbing water, so that it could maintain the sheet form. Since the fibrous CMC in the sheet that absorbed water had high gel strength and elasticity, the entire sheet also had elasticity and no slimming was felt. The pH of the paper surface was 6-7, which was in the neutral range.

Next, two disposable lunch boxes made of polystyrene foam and comprising a container and a lid are prepared, and a hot-melt type pressure-sensitive adhesive (Topco P618A, manufactured by Toyo Peterlight Co., Ltd.) is provided inside one of the lids. Was applied, and the above-mentioned swellable sheet was adhered. Immediately after cooking, 300 g of cooked rice was put into two lunch boxes, each of which was left with a lid to which a swellable sheet was attached and a lid to which no swelling sheet was attached. After 4 hours, the lid was opened, and the state of the cooked rice was observed, and when the swelling sheet was attached to the lid, the water content of the cooked rice did not increase because the water vapor of the condensed cooked rice was absorbed in the swellable sheet, The cooked rice did not become watery. On the other hand, in the case where the swellable sheet was not stuck on the lid, the cooked rice absorbed dew water and became watery, and the commercial value of the food was significantly reduced.

From these results, it can be seen that the swellable sheet according to the present invention can prevent the condensation water from adhering to foods such as cooked rice by absorbing the water condensation of the water vapor, and is used for packaging containers of various foods. It turns out that it is effective.

Example 2 A fibrous CMC Na salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 100%) was dispersed in water to prepare a 1.5% concentration dispersion. did. Polyethyleneimine resin (Nippon Shokubai Kagaku Kogyo Co., Ltd. brand name Epomin SP200, number average molecular weight 20,000, branched structure, containing primary, secondary and tertiary nitrogen atoms) was added to this fibrous CMC
Stirring was added in a proportion of 1% by weight relative -Na salt stock was prepared to prepare a handsheets having a basis weight of 60 g / m ² according to JIS P8209 using this stock.

For the obtained swellable sheet, the amount of water absorption,
The wet tensile strength and the sliminess in a wet state were evaluated, and the results are shown in Table 1. As shown in Table 1, the product of the present invention based on Example 2 absorbs 13 times the amount of its own weight of tap water and has a high wet strength even after absorbing water, so that it can maintain a sheet form. Was. Fibrous CM in water-absorbed sheet
Since C had a high gel strength, slimming was hardly felt. The paper surface pH was in the range of 6 to 8, and the same swellable sheet as in Example 1 was obtained.

Example 3 A fibrous CMC Na salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 95%) was dispersed in water to give a 1.5% concentration dispersion. Na of this fibrous CMC
2% by weight of polyamine resin (FR-2P) based on salt
And 80 parts by weight of the stirred dispersion, and 20 parts by weight of a 1.5% -concentrated dispersion obtained by disintegrating dissolving pulp (manufactured by Sanyo Kokusaku Pulp Co., Ltd.) to obtain a papermaking raw material. A sheet having a basis weight of 30 g / m ² was produced using a paper machine.

The obtained swellable sheet was evaluated for water absorption, wet tensile strength, and sliminess in a wet state, and the results are shown in Table 1. As can be seen from Table 1, the product of the present invention based on Example 3 absorbs 10 times its own weight of tap water and has high wet strength even after absorbing water, so that it can maintain the sheet form. Was. Fibrous CMC in water-absorbed sheet
Since the gel had high gel strength and elasticity, the entire sheet also had elasticity and no slimming was felt. Paper pH is 6
〜7 was in the neutral region.

On the swellable sheet, 15 superabsorbent resins (Aquakeep 10SH, trade name, manufactured by Sumitomo Seika Co., Ltd.) were added.
g / m ² after spraying, the same sheet is stacked and embossed to obtain a swellable sheet / highly water-absorbent resin / swellable sheet.
A laminate composed of layers was produced. The three-layer structure has a lower absorption rate of tap water dropped on the laminate than the laminate composed of tissue paper / high water-absorbent resin / tissue paper (basis weight of tissue paper: 18 g / m ² ). It was quick. Further, water droplets dropped on the swellable sheet constituting the three-layer laminate are quickly diffused and absorbed by the swellable sheet, and then water in the voids of the swellable sheet is absorbed by the superabsorbent resin to swell. In order to make the permeable sheet close to a dry state, even if water droplets are dropped again on the swellable sheet, the swellable sheet can be quickly absorbed.

Accordingly, the three-layer laminate using the swellable sheet is used in conventional feminine hygiene products, disposable diapers, etc., in combination with conventional fluff pulp (defibrated cotton-like pulp) and tissue paper / high water-absorbent resin / tissue. It could be suitably used in place of the combination of paper laminates, and because bulky fluff pulp was not used, the overall size and thickness could be reduced.

Example 4 A two-layer laminated paper comprising a water-absorbing layer and a heat-sealing layer was produced as follows.

Na salt of fibrous CMC (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 90%)
Was dispersed in water to a concentration of 1.5%, and 2% by weight of a polyamine resin (FR-2P) based on the Na salt of the fibrous CMC was added thereto. 20 parts by weight of a dispersion obtained by disintegrating a core-sheath type heat-fusible conjugate fiber (manufactured by Daiwa Spinning Co., Ltd., trade name NBF-E: hereinafter abbreviated as “NBF”) to a concentration of 1.5%. Was prepared and used as a first papermaking raw material for forming a water-absorbing layer. Here, NBF was blended for bonding with the heat seal layer and for reinforcing the wet strength of the water absorbing layer.

On the other hand, softwood bleached wood pulp (hereinafter referred to as “NB
KP) at 550 ml CSF in Canada
After beaten to the paper, wet strength imparting agent for papermaking (Dick Hercules Co., Ltd., trade name Caimen 557H) was added in a solid content of 0.3% by weight based on the absolute dry weight of NBKP, and then NBF was added to NBKP with respect to NBKP. : NBF = 40: 60 (weight ratio) to prepare a second papermaking raw material for forming a heat seal layer.

The above two types of papermaking raw materials are introduced into individual cylinders of a mesh type paper machine provided with two mesh cylinders, and a first wet paper web formed from the first papermaking material is provided. Second
A second wet paper web formed from the papermaking raw material of
A two-layer laminated paper having a basis weight of 70 g / m ² and having water absorption on one side and heat sealing on the other side was prepared. First
The basis weight of the water-absorbing layer formed from the wet paper is 50 g / m ² , and the basis weight of the heat seal layer formed from the second wet paper is 20 g
/ M ² .

With respect to the obtained swellable two-layer laminated sheet, the water absorption, the wet tensile strength and the slickness in a wet state were evaluated. The results are shown in Table 1. As can be seen from Table 1, the laminated body including the layer composed of the swellable structure according to the present invention absorbs eight times its own weight of tap water and has a high wet strength even after water absorption. The form could be maintained. Since the fibrous CMC in the sheet that has absorbed water has a high gel strength, it does not feel slimy at all, and the paper surface pH is 6-7.
And was in the neutral region.

The heat-seal surfaces of the swellable two-layer laminated sheet were put together at 160 ° C., 2 kg / cm ² (0.
Heat sealing under the condition of 196 MPa) for 2 seconds,
The heat seal strength of a test piece having a width of 15 mm measured by a T-peel tester was 500 g / 15 mm (327 N /
m), and had sufficient strength for practical use. From the above, it is clear that a sheet having heat-sealing properties on one side and a water-absorbing swelling property on the other side can be obtained, and the swellable structure according to the present invention can be combined with another material such as a synthetic film. And bag making can be performed very easily.

Example 5 A fibrous CMC Na salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.35, base saturation: 95%) was dispersed in water to give a 1.5% concentration dispersion. Na of this fibrous CMC
3% by weight of polyamine resin (FR-2P) based on salt
Was added and the stirred dispersion was used as a mold raw material.

Length × width × depth = 20 cm × 20 cm × 10
A convex mold for molding for molding a cm tray was prepared. The molding die is formed of a porous metal plate having a 150 mesh mesh at the side contacting the side and bottom surfaces of the tray, and fitted with a suction pipe capable of depressurizing the inside. After immersion, the inside of the mold was depressurized to deposit fibers on the surface of the wire mesh to a thickness of 2 to 3 mm, dewatered by press, and then dried to take out the molded product from the mold.

The obtained molded product was evaluated for water absorption and slimming in a wet state. The molded product absorbed 10 times the amount of tap water of its own weight, and was able to maintain the form of the molded product even after absorbing water. The fibrous CMC in the molded article that has absorbed water has high gel strength and elasticity, so the entire molded article has elasticity, no sliminess is felt, and the paper surface pH
Was in the range of 6-7.

Example 6 A 1% concentration dispersion of fibrous CMC Na salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 95%) was prepared by dispersing in water. Then, a cationic polyacrylamide resin (manufactured by Meisei Chemical Industry Co., Ltd., trade name: AG Fix M15, cation equivalent: 4.5 meq / g, containing quaternary nitrogen atom) was added to Na of the fibrous CMC.
2.0 wt% or 4.0 wt% was added to the salt and stirred to prepare two types of stock. Using these stocks, two types of basis weight 60 based on JIS P8209
A g / m ² handsheet was prepared.

About the obtained swellable sheet, the water absorption,
The wet tensile strength and slimming in a wet state were evaluated, and the results are shown in Table 2. For comparison, the evaluation results of a cellulose-based dry nonwoven fabric having a basis weight of 68 g / m ² are also shown in Table 2 as comparative products. As can be seen from Table 2, the product of the present invention based on Example 6 absorbs 10 to 11 times its own weight of tap water, and after absorbing water, 90 to 120 g / 15 mm (59 to 78).
N / m), the sheet form could be maintained. Since the fibrous CMC in the water-absorbed sheet had a high gel strength, the entire sheet was hardly smeared. The paper pH was 6-7, in the neutral range.

Example 7 A fibrous CMC Na salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 95%) was dispersed in water to prepare a dispersion having a concentration of 1%. 1. concentration of chitosan
A chitosan solution (manufactured by Katakura Tikkalin Co., Ltd., containing primary and secondary nitrogen atoms, cation equivalent of 4.2 meq / g) dissolved in an aqueous lactic acid solution to 5% with respect to the Na salt of the fibrous CMC was used. Then, 2.5% by weight or 10% by weight was added and stirred to prepare two types of stock. Using these stocks, two types of basis weight 60 based on JIS P8209
A g / m ² handsheet was prepared.

For the obtained swellable sheet, the water absorption,
The wet tensile strength and slimming in a wet state were evaluated in the same manner as in Example 6, and the results are shown in Table 2. As can be seen from Table 2, the product of the present invention based on Example 7 absorbs 7 to 9 times its own weight of tap water, and even after absorbing water, 210 to 450 g / 15 mm.
(137 to 294 N / m), the sheet form could be maintained. Since the fibrous CMC in the water-absorbed sheet had a high gel strength, almost no slimming was felt on the entire sheet as in Example 6. The paper pH was 6-7, in the neutral range.

Example 8 50% by weight of methacryloyloxyethyltrimethylammonium chloride and 50% by weight of acrylamide were dissolved in water to a concentration of 10% by weight, and ammonium persulfate was used as an initiator and heated to 70 to 75 ° C. to carry out polymerization. After that, purification was carried out by fractional precipitation in a water-methanol system to prepare a copolymer. This copolymer had a quaternized nitrogen atom and had a cation equivalent of 3.2 meq / g at pH 6. Next, Na salt of fibrous CMC (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, degree of base saturation: 95%)
Was dispersed in water to prepare a dispersion having a concentration of 1%. 4.0% by weight of the above copolymer was fractionated with respect to the fibrous CMC Na salt, dissolved in water to a concentration of 1%, added to the fibrous CMC Na salt, and stirred to obtain paper. From this paper material, a handsheet having a basis weight of 60 g / m ² was prepared based on JIS P8209.

The swellable sheet obtained had a water absorption,
As a result of evaluating the wet tensile strength and the slimming in a wet state, as shown in Table 2, the product of the present invention based on Example 8 absorbed 10 times the amount of tap water of its own weight, and even after absorbing water 100 times.
Since it had a wet tensile strength of g / 15 mm (65 N / m), the sheet form could be maintained, and no slimming was felt. The paper pH was 6-7, in the neutral range.

Example 9 45 g of dimethylamine liquefied by cooling to -20 ° C.
(66 ml, 1 mol) at 15 ° C epichlorohydrin 9
2 g (1 mol) was added dropwise over 2 hours, left at 15 ° C. for 4 hours, added with 20 ml of pure water, heated at 70 ° C. for 24 hours to polymerize, and the secondary amine / epichlorohydrin polyaddition polymer was obtained. Prepared. The reaction solution was poured into acetone, and the precipitate was dried to obtain the polymer as a solid. The cation equivalent of this solid was 6.2 meq / g at pH 6, and the average molecular weight (styrene equivalent) determined by gel permeation chromatography was 8,900. next,
A fibrous CMC Na salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 90%) was dispersed in water to prepare a 1% concentration dispersion. Na of fibrous CMC
The solid matter of 2.0% by weight based on the salt was fractionated, dissolved in water to a concentration of 1%, added to the Na salt of the fibrous CMC, and stirred to prepare a stock. From stock to JIS P
A handsheet having a basis weight of 70 g / m ² was prepared based on 8209.

For the obtained swellable sheet, the water absorption,
As a result of evaluating the wet tensile strength and the slimming in a wet state, as shown in Table 2, the product of the present invention based on Example 9 absorbs 12 times the amount of its own weight of tap water and retains 110% of the water after absorption.
Since the sheet had a wet tensile strength of g / 15 mm (72 N / m), the sheet form could be maintained. Since the fibrous CMC in the sheet that absorbed water had high gel strength and elasticity, the entire sheet also had elasticity and no slimming was felt. The paper pH was 6-7, in the neutral range.

Example 10 62 g (1 mol) of a 50% by weight aqueous solution of monomethylamine was mixed with 175 g of methanol, and 184 g (2 mol) of epichlorohydrin was added to the mixture at a reaction temperature of 30 to 30%.
The solution was added dropwise at such a rate as to keep it in the range of 40 ° C., and kept at 40 ° C. for 12 hours to obtain 51% by weight of partially polymerized bis (3-chloro-2-hydroxypropyl) methylamine.
A methanol solution was prepared. The above methanol solution 2
79 g @ bis (3-chloro-2-hydroxypropyl)
0.5 mol% as methylamine, 67 g (0.6 mol) of N, N, N ', N'-tetramethyl-1,2-diaminoethane and 100 g of pure water were mixed, and the mixture was mixed at 80 to 90 ° C for 20 minutes.
After maintaining for a period of time, 400 g of pure water was added and the mixture was cooled. The pH after the reaction was adjusted to 4 by adding concentrated sulfuric acid, and the primary amine / epichlorohydrin / ditertiary amine represented by the following formula was obtained. An addition polymer was obtained.

[0082]

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The cationic equivalent of this polymer was 4.5 meq / g at pH 6, and the viscosity of a 25% by weight aqueous solution was 1200 centipoise. Next, fibrous C
An MC Na salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 90%) was dispersed in water to prepare a 1% concentration dispersion. An aqueous solution of the polymer was fractionated in terms of solid content in an amount of 2.0% by weight based on the Na salt of the fibrous CMC, added to the Na salt of the fibrous CMC, and stirred to prepare a stock. A handsheet having a basis weight of 70 g / m ² was prepared from the stock based on JIS P8209.

About the obtained swellable sheet, the water absorption amount,
As a result of evaluating the wet tensile strength and the slimming in a wet state, as shown in Table 2, the product of the present invention based on Example 10 absorbs 11 times the amount of its own weight of tap water and retains 90% of water after absorbing water.
Since the sheet had a wet tensile strength of g / 15 mm (59 N / m), the sheet form could be maintained. Since the fibrous CMC in the sheet that absorbed water had high gel strength and elasticity, the entire sheet also had elasticity and no slimming was felt. The paper pH was 6-7, in the neutral range.

Example 11 N, N, N ', N'-tetramethylethylenediamine 116
g (1 mol), 142 g (1 mol) of dichloroethyl ether and 150 g of pure water are mixed,
By heating for an hour, an aqueous solution of a dihalo compound / ditertiary amine polyaddition polymer represented by the following formula and having a concentration of 63% by weight was prepared.

[0086]

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This polymer has almost all nitrogen atoms of 4
The cation equivalent was 7.0 meq / g at pH 6. Next, Na salt of fibrous CMC (manufactured by Nichirin Chemical Co., Ltd., etherification degree 0.43, base saturation degree 9)
(0%) was dispersed in water to prepare a dispersion having a concentration of 1%. The aqueous solution of the above polymer was converted to fibrous C
2.0% by weight based on the Na salt of MC was added to the Na salt of the fibrous CMC and stirred to prepare a stock, and the basis weight was 70 g / m ² based on JIS P8209 based on this stock.
Was manufactured.

For the obtained swellable sheet, the water absorption,
As a result of evaluating the wet tensile strength and the slimming in a wet state, as shown in Table 2, the product of the present invention based on Example 11 absorbed 10 times the amount of its own weight of tap water, and even after absorbing water, 15 times.
Since it had a wet tensile strength of 0 g / 15 mm (98 N / m), the sheet form could be maintained. Since the fibrous CMC in the sheet that absorbed water had high gel strength and elasticity, the entire sheet also had elasticity and no slimming was felt. The paper pH was 6-7, in the neutral range.

Example 12 208 g (1.1 mol) of tetraethylenepentamine was dissolved in 50 g of pure water.
g (1.1 mol) was gradually dropped, and 50 g of pure water was added.
The mixture was adjusted to a slight reflux and heated for 3 hours. 90 g (2.2 mol) of sodium hydroxide is dissolved in 100 g of pure water and gradually added to the resulting polyethylene polyamine hydrochloride for neutralization, and sodium chloride produced as a by-product is removed. Of 4
An aqueous solution having a concentration of 6% by weight was obtained. Next, the fibrous CMC N
a salt (manufactured by Nichirin Chemical Co., Ltd., degree of etherification 0.43,
A base dispersion (90% base saturation) was dispersed in water to prepare a 1% concentration dispersion. 2.0% by weight of the aqueous solution of the above-mentioned polyethylene polyamine resin in terms of solid content was fractionated with respect to the Na salt of the fibrous CMC, added to the Na salt of the fibrous CMC, and stirred to prepare a stock. JIS P82 from this stock
09, a handsheet having a basis weight of 70 g / m ² was produced.

About the obtained swellable sheet, the water absorption,
As a result of evaluating the wet tensile strength and the slimming in a wet state, as shown in Table 2, the product of the present invention based on Example 12 absorbed 10 times the amount of its own weight of tap water, and even after absorbing water, 95%.
Since the sheet had a wet tensile strength of g / 15 mm (62 N / m), the sheet form could be maintained. Since the fibrous CMC in the sheet that absorbed water had high gel strength and elasticity, the entire sheet also had elasticity and no slimming was felt. The paper pH was 6-7, in the neutral range.

Example 13 116 g (1.0 mol) of hexamethylene diamine was dissolved in 108 g of pure water, and 92 g of epichlorohydrin was added thereto.
(1.0 mol) was gradually added dropwise at 45 to 50 ° C.
After heating for an hour, acetic acid was added to adjust the pH to 5, thereby obtaining a polyamine resin, a diamine / epichlorohydrin polycondensate. Next, Na salt of fibrous CMC (manufactured by Nichirin Chemical Co., Ltd., degree of etherification: 0.43, base saturation: 90%)
Was dispersed in water to prepare a dispersion having a concentration of 1%. The aqueous solution of the above polyamine resin is converted into fibrous C
2.0% by weight based on the Na salt of MC was added to the Na salt of the fibrous CMC and stirred to prepare a stock, and the basis weight was 70 g / m ² based on JIS P8209 based on this stock.
Was manufactured.

The swellable sheet obtained had a water absorption,
As a result of evaluating the wet tensile strength and the slimming in a wet state, as shown in Table 2, the product of the present invention based on Example 13 absorbed 10 times the amount of tap water of its own weight, and even after absorbing water, 90%.
Since the sheet had a wet tensile strength of g / 15 mm (59 N / m), the sheet form could be maintained. Since the fibrous CMC in the sheet that absorbed water had high gel strength and elasticity, the entire sheet also had elasticity and no slimming was felt. The paper pH was 6-7, in the neutral range.

[0093]

[Table 1]

[0094]

[Table 2]

[0095]

According to the present invention, a swellable structure having a high wet strength, capable of absorbing a sufficient amount of liquid, retaining its original shape even when swollen, and preventing slimming. It does not require a surface layer and has a high liquid absorption rate, and can be used in various applications as a liquid-absorbing swellable structure in various forms. In addition, since it is neutral, it can be used without a surface layer in applications that come into direct contact with food or the like.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI D21H 5/00 Z

Claims (6)

(57) [Claims] 1. A swellable structure comprising a fibrous carboxymethylcellulose salt, comprising a repeating unit having at least one selected from a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom and a quaternary nitrogen atom. A polyelectrolyte complex is not formed on at least a part of the fibrous carboxymethylcellulose salt by a cationic water-soluble polymer substantially free of a functional group capable of forming a cross-linking bond other than these nitrogen atoms. Water is absorbed by external force
Therefore swellable structure characterized Rukoto cormorants discharged. 2. The swellable structure according to claim 1, wherein
A cationic water-soluble polymer, chitosan, a polymer having a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom or a quaternary nitrogen atom in a side chain of a polymer and a primary nitrogen atom in a main chain of the polymer; A swellable structure comprising at least one selected from polymers having a secondary nitrogen atom, a tertiary nitrogen atom or a quaternary nitrogen atom. 3. The swellable structure according to claim 2, wherein
A swellable structure in which the polymer having a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom, or a quaternary nitrogen atom in the main chain of the polymer is an ionene polymer, polyethyleneimine, a polyamine resin, or a polyamine polyamide. 4. A salt of fibrous carboxymethylcellulose.
Is dispersed in water, contains a repeating unit having at least one selected from a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom and a quaternary nitrogen atom, and in addition to these nitrogen atoms, A cationic water-soluble polymer substantially free of a functional group that generates a cross-linking is added to prepare a paper stock in which a polymer electrolyte complex is formed on at least a part of the fibrous carboxymethylcellulose salt, A method for producing a swellable structure, comprising dewatering and shaping the stock. 5. The method for producing a swellable structure according to claim 4, wherein the cationic water-soluble polymer is chitosan, a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom or a primary nitrogen atom in a side chain of the polymer. Swelling characterized by being at least one selected from a polymer having a quaternary nitrogen atom and a polymer having a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom or a quaternary nitrogen atom in the main chain of the polymer. Method for producing a conductive structure. 6. The method for producing a swellable structure according to claim 5, wherein the polymer having a primary nitrogen atom, a secondary nitrogen atom, a tertiary nitrogen atom, or a quaternary nitrogen atom in the main chain of the polymer is selected from the group consisting of: A method for producing a swellable structure which is a linen polymer, polyethyleneimine, polyamine resin or polyamine polyamide.