JPH03269199A - Bulky pulp sheet and production thereof - Google Patents

Abstract

PURPOSE:To obtain a bulky pulp sheet having excellent hydrophilic properties and liquid absorbing properties by mixing pulp with a specific polyester composite fiber and thermally fusible binder fiber using a high speed mixer and dispersing these ingredients and laminating the mixed fiber and thermally treating the laminate. CONSTITUTION:The aimed mixed fiber obtained by mixing (A) 40-90wt.% cellulose pulp with (B) 5-60wt.% eccentric core-sheath type or side by side type polyester composite fiber whose crimp form is three-dimensional and (C) 5-50wt.% thermally fusible binder fiber and dispersing these components, laminating the mixed fiber and drying or thermally treating the laminate at 80-180 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a bulky pulp sheet with excellent hydrophilicity and liquid absorbency.

<Prior art> A method of forming a sheet using cellulose pulp using a dry molding method is described on page 27 of the Nonwoven Fabric Technology Seminar Textbook (Kagaku Fraen Co., Ltd., Osaka, 62.2.17). However, the essential drawback is that the cellulose bulb must be laminated with a binder, so the pulp fibers are wetted by the binder and the bent pulp fibers are inevitably laminated in a two-dimensional manner. On the other hand, pulp fibers have a short fiber length, so there is less intertwining among fibers, so a large amount of binder is required, 10 to 40 inches per sheet weight, which makes the sheet hard, and the properties of the binder become stronger. There is a problem with its hygiene.

Anyway, there is a limit to the bulkiness of that sheet, and it is 2.5 f.
No sheet with an apparent density of 0.04f or less measured under a /cli load was obtained. In addition, from the viewpoint of productivity, they must be laminated quietly in order not to lose their bulkiness, which has the disadvantage that an improvement in production speed cannot be expected.

<Problems to be Solved by the Invention> The present invention further improves the bulkiness, which is limited by the conventional pulp dry sheet forming method, and by mixing binder fibers, it can be made with a small amount of organic binder or even without using an organic binder. The object of the present invention is to provide the sheet with bulkiness, strength, flexibility, high water absorption, and stiffness when water is absorbed, and to provide a manufacturing method thereof.

Means for Solving the Problems> That is, the present invention provides an eccentric core-sheath type or side pie-side type polyester composite fiber with 40 to 90 weight % cellulose pulp and a three-dimensional crimp form - 5 to 60 weight % cellulose pulp. % and heat-fusible binder fiber from 5 to 50% by weight? ), 2.5
The apparent density determined from the thickness under f/- load is 0.04f
/c1d or less, and it is particularly preferable to use a polyolefin-based, polyvinyl acetate-based, acrylic-based,
At least one thermoplastic or thermosetting resin selected from phenol, evo, xy, and vinyl chloride resins, or at least one water-soluble polymer selected from polyvinyl alcohol, starch, and cellulose. This is a sheet to which 5% by weight or less of an organic binder is attached.

And, such a bulky pulp sheet contains 40~90ii% of cellulose valve and 05~90ii% of polyester composite fiber.
60 East 1% and heat-fusible binder fiber 5-5ajt'
It can be produced by mixing and dispersing 1kes with a high-speed stirring mixer, laminating the mixed fibers on a net, for example, while spraying an organic binder as necessary, and drying or heat-treating the fibers at 80 to 180°C.

The cellulose bulb used in the present invention is preferably unbleached or bleached pulp from softwood or hardwood, fibrous material such as waste paper, or a powder obtained by crushing fibers in a fist. These fibers have a short length of 10 cm or less and can be uniformly dispersed in the air. The mixing ratio is 40 to 90 inches, preferably V150 to 80 inches. If it is less than 40%, the pulp component will be reduced and the liquid absorption rate will be poor, which is not preferable, and if it exceeds 90%, a bulky pulp sheet will not be obtained. As other cellulose bulbs, bast fibers such as kozo, mitsumata, hemp, and ramie, vegetable fibers such as cotton linters, bamboo, and wheat straw can also be used in the same way. Eccentric core-sheath type or side pie-side type polyester composite fibers (hereinafter simply referred to as polyester composite fibers), which are crimped, are basically composed of polymers with different shrinkage rates of 28[, for example, As the polymer component (A), the main repeating structural unit preferably consists of ethylene terephthalate,
and 1 to 6 mol of isophthalic acid having a metal sulfonate group and 0 to 8 mol of inphthalic acid as copolymer components.
A modified polyester having a mole fraction in the range of 0 can be used. Even if isophthalic acid is not copolymerized,
The polymerization reaction of polyester proceeds moderately, and it is possible to produce polyester composite fibers having a latent crimp ability within the range of the present invention. is preferred. Further, isophthalic acid having a metal sulfonate group to be copolymerized is used to maintain an appropriate melt viscosity and to realize the ability to develop latent crimp within the scope of the present invention. Isophthalic acids having a metal sulfonate group include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, and 5-potassium sulfoisophthalic acid.
Examples include lithium sulfoinphthalate. Polymer (A) can be obtained by copolymerizing an ester-forming compound having a metal sulfonate group such as these ester-forming derivatives with a polyethylene terephthalate polymer by adding isophthalic acid as necessary. In addition to this, a polyethylene terephthalate polymer is prepared in advance by copolymerizing a high proportion of isophthalic acid having a metal sulfonate group, and if necessary, a polyethylene terephthalate polymer is also prepared by copolymerizing a high proportion of isophthalic acid. The copolymerization ratio of these is 1 to 6 mol and 0, respectively.
It can also be obtained by a masterbatch method, etc., in which it is mixed with polyethylene terephthalate so that the concentration ranges from 80 mol. If the copolymerization ratio of isophthalic acid having a metal sulfonate group is less than 1 molar, the development of shrinkage stress during heat treatment is weak and crimp development is poor. If the molar ratio exceeds 6, the melt viscosity of the polymer becomes too high, making it difficult to stably obtain a polymer with an appropriate degree of polymerization in the condensation reaction, and the crystallinity during spinning increases, making it easy to change over time. 0 Preferably 1 to 5 mol, which results in a decrease in drawability and makes it impossible to obtain a composite fiber with sufficient latent crimpability.
More preferably, the amount is 2 to 4 mol. Furthermore, copolymer components other than those mentioned above may be introduced into the polymer (A) as long as the shrinkage properties are not significantly impaired. Moreover, the intrinsic viscosity of the polymer (A) is preferably 0.45 to 0.66.

As the low-shrinkage polymer component (B), for example, polyester consisting essentially of polyethylene terephthalate is used. Of course, the polymer (B) may be copolymerized as long as it does not significantly reduce the crimp effect of the polymer (A). In addition, the intrinsic viscosity of the polymer (B) is 0.60.
A degree of polymerization of ˜0.70 is preferred.

If necessary, inorganic substances such as titanium oxide, zirconium oxide, silicon oxide, alumina, and other ceramics, or flame retardants, antibacterial agents, deodorants, fragrances, and hydrophilic agents such as sodium dodecylbenzenesulfonate may be mixed. It's okay. Additionally, other polymers may be added to the polymers (A) and (B) to the extent that the crimpability of the fibers is not significantly impaired.

The spinneret to be used may be a composite type spinneret having irregular shapes such as a round shape, a triangular shape, a ten shape, an omega shape, a T shape, etc., but is of course not limited to these, and the composite shape is also not particularly limited. However, the side pie-side type is generally preferable to the eccentric core-sheath type because it has better crimp development ability.

The polyester composite fibers used in the present invention are (A), (
B) The two types of polymer components were heated in the range of 270 to 290°C using the above-mentioned die, and the composite ratio (A): (B) = 40.
-60:60-40, it is particularly preferable to use an eccentric core-sheath type or a side pie-side type conjugate fiber, preferably a side pie-side type conjugate fiber as described above. The melt viscosity of the two types of polymer components at the time of spinning is always (A) > (B), and the difference in viscosity at the time of melting is 100 to 1500 poise,
Preferably, the range is from 300 to 1000 poise in order to obtain composite spun fibers having excellent latent crimp ability. As the composite ratio deviates from 50:50, the two-ing phenomenon is more likely to occur at the discharge portion of the nozzle, so a range of (A):(B) = 45-55:55-45 is most preferable.

Next, in order to impart bulkiness, flexibility, stretchability, and elongation recovery to the sheet, it is important to heat-treat the polyester composite fibers to develop three-dimensional crimp, especially spiral crimp. Furthermore, the number of spiral crimps and the shape of the crimps at that time (
It is important that the curvature) is sharp, and specifically, the number of crimps is 30/2 by dry heat treatment at 80 to 180°C.
It is preferable that spiral crimp is developed at 5 wm or more. If the number of crimps is less than 30 crimps/25 m, bulkiness, flexibility and stretchability will be significantly reduced, resulting in a sheet with high bulk density. In addition, the shrinkage rate during heat treatment has an important relationship with the texture, bulkiness, and elasticity of the sheet, and the preset temperature and final dry heat treatment temperature, which are general processing conditions, are 80 to 80℃.
It is best to choose a temperature that satisfies 180°C.

Polyester composite fibers having such latent crimp ability and heat shrinkability are characterized by a difference in melt viscosity between the polymer (A) on the high shrinkage side and the polymer (B) on the low shrinkage side, and It can be obtained by appropriately selecting the copolymerization ratio in , the composite ratio of (A) and (B), and the stretching conditions and tension heat treatment conditions in the post-spinning stretching step.

The stretching conditions are such that latent crimp ability can be maximized by stretching the fiber after spinning at a maximum stretching ratio of 60 to 75 inches, and in this state, tension heat treatment is performed in the range of 130 to 180°C. As a result, high crystallinity can be maintained and high potential crimp force can be cultivated.

However, uncrimped polyester composite fibers may be used for dry molding, but in order to further improve crimpability and dispersibility, they are uncrimped during dispersion using a push-type crimper, which is a common method. Mechanical crimp to the extent that dispersion does not occur, number of crimp is 3 to 20
It is also possible to use raw cotton to which a weight of /25m has been applied. The number of crimps is 20
Care: If the length exceeds 25 m, it is not preferable because the mixer or disperser will not be able to sufficiently disperse it. The fineness of the polyester composite fiber is preferably 0.5 to 15 deniers, more preferably 2 to 6 deniers. If it is less than 0.5 denier, the ability to develop spiral crimp is good, but the ability to develop crimp is weak, and it is difficult to obtain bulkiness. Further, in a region exceeding 15 denier, the sheet becomes stiff and lacks flexibility, and furthermore, the strength of the sheet becomes weak, which is not preferable. Fiber length is 3~
If the fiber length is less than 30 cm, the fibers are too short and there is little entanglement between the fibers, which is not preferable. On the other hand, if the length exceeds 30 m, the entanglement of the fibers during dispersion becomes too strong, causing fluffing, making it impossible to obtain a uniformly dispersed flocculent.

The high performance effect is small and undesirable. Moreover, if it exceeds 60 inches, it is not suitable because of problems such as poor water absorption speed and lack of playability.

The heat-fusible binder fibers used in the present invention include, for example, polyolefin fibers such as polyethylene and polypropylene, modified polyesters and polyamides whose melting points or softening points have been lowered by copolymerization, and ethylene-vinyl alcohol fibers. Synthetic fibers made of a single component selected from polyvinyl alcohol copolymers such as ethylene-vinyl acetate-vinyl alcohol copolymers, or sheath components are made of components selected from the above polymers, and the core component is not present. Core-sheath type composite fibers made of modified polyester, polypropylene, polyamide, or other polymers can be used.

In addition, *i of the heat-fusible binder fiber is preferably 1 to 6 deniers; if it is less than 1 denier, the dispersibility will deteriorate, which is undesirable; if it exceeds 6 denier, it will not be resistant to 20 denier.
A crimp of 25 vm or less may be provided. 20 pieces/25■
If the crimping exceeds 0 or more fiber length, threads are likely to become entangled during dispersion! An i of 2 to 60 is good; if it is less than 2, it is difficult to obtain a binder effect, and if it is more than 60, it will pill and the dispersion will deteriorate.

The blending ratio of the heat-fusible binder fiber is required to be 5 to 50% by weight, preferably 10 to 40% by weight. If it is less than 5% by weight, it will not be effective in improving sheet strength and elasticity recovery when mixed with polyester composite fibers and cellulose pulp, and preventing the occurrence of fuzz on the sheet surface.

Next, as an effect of improving the strength and imparting hardness to the obtained sheet, an emulsion or aqueous solution of thermoplastic, thermosetting, water-soluble, etc. can be attached as an organic binder.

Preferred thermoplastic emulsions include polyolefins such as polyethylene and polypropylene, polyvinyl acetate, and polyvinyl chloride, and polyvinylidene chloride, polyamide, polyurethane, and polyester emulsions can also be used.

As thermosetting emulsions, acrylic, phenol, and epoxy emulsions are preferred, but amine-based resins such as urea, ethylene urea, melamine, and benzoguanomine produced by reaction with formalin, resol-based emulsions, etc. Novolak-based, furan-based, polyisocyanate-based, etc., and copolymers thereof can also be used.

Water-soluble resins for imparting hydrophilic properties to the sheet include natural starch-based resins, and modified starches such as dextrin, acid-modified starch, oxidized starch, and other starch derivatives are preferred.

Examples of cellulose-based materials include complex polysaccharides such as gum arabic, gum tragacanth, guar gum, and alginic acid, and other protein-based materials such as casein, soybean protein, albumin, glue, and gelatin can also be used. On the other hand, polyvinyl alcohol and copolymers thereof are preferable as synthetic materials, and other materials such as inbutene-maleic anhydride copolymer, polyacrylamide, polyethylene oxide, polyvinylpyrrolidone, polyvinyl acetate copolymer, acrylic copolymer, etc. may be used. I can do it.

Examples of methods for applying such an organic binder to fibers include a method in which the organic binder is uniformly sprayed onto the fibers dispersed in the air before the lamination process, and a method in which the organic binder is sprayed or impregnated after the fibers are laminated. It will be done. The amount of the organic binder attached is preferably 5% by weight or less based on the weight of the sheet. In consideration of texture and bulkiness, it is not necessary to use an organic binder. If more than 5 inches of binder is used, not only will the bulkiness not be obtained, but the properties of the binder will become stronger, which is not preferable.

When producing bulky pulp sheets, cellulose pulp is kept in a dry state to maximize its dispersibility even when the pulp is made into a sheet with fibrous materials or when pulp fibers are crushed into powder. For this purpose, the material is put into a blade-like pulper or mixer that can be pulverized or disintegrated at high speed in the air, and disintegrated until it becomes a single fiber or individual particles.
Spread. Separate with an air cyclone or vibrating mesh to remove undispersed or impurities.

A predetermined amount of dry polyester composite fibers having a moisture content of 0 to 10% is added and mixed into the obtained cellulose pulp. The input amount is 15 to 60% of the sheet weight, and the rate is 10,000 to 20,000 rpm, similar to cellulose pulp.
Mix and stir at m. Alternatively, it may be defibrated with mixed cotton.

Furthermore, the heat-sealable binder effect fibers specified in the present invention are added to the mixed fibers and mixed and stirred in the same manner to obtain a mixed fiber flocculent. In order to prevent undefibrated matter and lumps from being mixed into the mixed cotton material and to further improve the uniformity of mixing, a roller card may be passed through the entire length, or a clothed roller such as a card roller may be used. In between, it may be used as crushed sliver or mixed cotton. A predetermined amount of mixed cotton is transported by air into a collection box by a rotary pulp that discharges a predetermined amount of mixed cotton.

Preferably, the box is equipped with an organic binder spraying device, a movable net for laminating sheets at the bottom, and a certain amount of air vent.

The mixed cotton material laminated to a predetermined basis weight or thickness is taken out from the net conveyor, placed in a radiant air bath at 80 to 250°C, and subjected to dry heat treatment at a substantially fiber temperature of 80 to 180°C. By carrying out this process, the bulky pulp sheet of the present invention can be obtained.

In order to impart strength to the obtained bulky pulp sheet, to harden the surface, and to prevent the occurrence of fluff, treatment may be carried out by spraying an organic binder.

The bulky pulp sheet thus obtained is characterized by its extremely high bulk, with an apparent density of 0.04 f/al or less when the thickness is measured under a load of 2.5 g/cm2.

In addition, regarding flexibility, although cellulose pulp has a large amount of 40 to 90 cm, the eccentric core-sheath type or side pie-side type polyester composite fiber that causes spiral crimp has a high flexibility in the thickness direction of the sheet, that is, in the three-dimensional direction. The polyester composite fibers and heat-fusible binder m-fibers have a spring-like shape and are flexible due to the sheet structure, and the synthetic fibers have a lower elastic modulus than cellulose pulp, making them flexible. It seems that there is.

Furthermore, regarding super absorbency, the apparent density is 0.04F15.
This is due to the bulkiness of 1 or less. In terms of stiffness when water is absorbed, cellulose pulp has an extremely low Young's modulus when wet, but since polyester composite fibers and heat-fusible binder fibers are hydrophobic, they are not affected by water and their Young's modulus is It is strong enough to hold and has a good texture.

As described above, the bulky sheet of the present invention is highly hydrophilic and has excellent liquid absorption amount and speed, so it is widely used in the field of disposable materials due to its texture.For example, it is used in sanitary materials. Absorbent material for sanitary napkins, disposable diapers, cooking oil absorbent material for household and industrial wipes, drip absorbent material to maintain freshness, moisture absorbent material for fresh vegetables, interlining for clothing,
It is used in slippers, shoes, etc., and can be used in a wide range of applications, including packaging materials, cushioning materials, and agricultural seeding sheets.

<Examples> Hereinafter, the present invention will be specifically explained with examples, but the present invention 8A is not limited to these in any way.

Examples 1 to 4 and Comparative Examples 1 to 2 Bleached softwood pulp sheets (Canadian Freeney,
760m)' Bulb-like material disintegrated and dispersed in a mixer at 16,000 rpm, polyester composite fiber with latent spiral crimp performance and arranging modified PET and PET in a side pie-side pattern (@Kuraray Co., Ltd.■ Sofit N- 7902.5 denier fiber length 5W crimps number 16/inch) and heat-fusible binder fiber,
The sheath part is a modified polyester that can be fused at 110°C, and the core part is a regular polyester. ■Made by Kuraray■ Sofit N720 (2 denier, fiber length 5 m)
) and Nisso gEA chop (3 denier fiber length, 5 days), which is a composite fiber with polyethylene sheath and polypropylene core, were mixed at 16,000 rpm for 2 minutes at the blending ratio shown in Table 1. Stir to obtain a homogeneous mixed floc.

A fixed amount of these mixtures is discharged between card-type needle rolls using air, and sent to a collection box equipped with a Teflon mesh that moves at a constant speed, while only air is exhausted through the Teflon mesh. Laminated. In addition, some (Examples 2 to 4, Comparative Examples 1 and 2) were sprayed with a predetermined amount of organic binder in spray form.
A bulky sheet as shown in Table 1 was obtained by drying at 0° C. for 2 minutes and heat treatment at the same time.

Examples 5 to 8 and Comparative Examples 3 to 5 Cellulose pulp made by dispersing powder pulp (crushed pulp) with a mixer of 1600 Orpm, and side pie side having the same spiral irrigation performance as Examples 1 to 4. type polyester composite fiber (Kuraray Sofit N790 2.5 denier fiber length 5 wm) and Kuraray Soffit N720 as a heat-fusion binder fiber
2 denier and R fiber length 5 cm) was mixed and stirred at 16,000 rpm for 2 minutes at the blending ratio shown in Table 2 to obtain a uniform mixed flocculent.

A bulky pulp sheet was otherwise obtained in the same manner as in Examples 1 to 4. Example 5 using only cellulose pulp for comparison
A sheet was formed in the same manner as in 8 to 8, and some (Examples 6 and 8, Comparative Example 4) were sprayed with a predetermined amount of organic binder, dried at 160° C. for 2 minutes, and heat treated at the same time. The results are shown in Table 2.
In the following, the method for measuring each characteristic value in the present invention is as follows.

(1) Intrinsic viscosity: Measured at 30°C in a mixed solution of equal weights of phenol and tetracyclized ethane.

(2) Fineness: JISL-1015-7-5-IA
Measured by the method.

(3) Number of crimps: JISL-1015-7-12~
Measured by method 1.

(4) Free shrinkage rate: JISL-1015-7-15
Measured according to the method of 30 minutes in an atmosphere of 170°C and a load of 30011v per denier.

(5) Measurement of sheet physical properties Weight: JISP 8124 bulk density 2 sheets are stacked together, a plastic plate is applied so that the thickness is 252/-, the thickness is measured with a micrometer, and the average value per sheet is Determined from thickness.

Strength and elongation: JISP8113 Liquid absorption amount: Water was used as the liquid substance.

The weight of the sample cut into a size of 10α×103 (wO
) to measure. Leave it immersed in water for 15 minutes and confirm that the air in the sample has been replaced.Pull up the sample into the air and measure the sample weight (Wl) when no droplets fall.

(6) Texture: The texture was determined as follows.

◎ Feels like rabbit fur (slimy and soft) ○ (soft feel)〃 Δ Feels like cloth (rough) X Feels like paper (crispy) (7) Dry The elastic recovery property is approximately 1 when the sheet is cut into 10 crn square sheets.
0c! Place the plastic on this surface and apply a total load of 500 tons. Leave it for 60 minutes, remove the load, and observe the recovery at the original thickness 1 after 60 minutes. did.

◎・・・・・・Recovery of 80 inches or more f8+ ○・・・・・・60-80 inches recoveryΔ・・・・・・40-60% 〃×・・・・・・20-40% 〃×× ...
...20 inches or less The wet elastic recovery was observed in the same manner as the dry elastic recovery under conditions in which sufficient water was contained.

Claims (7)

[Claims] (1) Cellulose pulp 40-90% by weight, eccentric core-sheath type or side pie-side type polyester composite fiber with three-dimensional crimp form; 5-60% by weight and heat-fusible binder fiber 5-50% by weight %, 2.5g/cm^2
The apparent density determined from the thickness under load is 0.04 g/cm^
A bulky pulp sheet with a thickness of 2 or less. (2) At least one thermoplastic or thermosetting resin selected from polyolefin, polyvinyl acetate, acrylic, phenol, epoxy, and vinyl chloride resins, or polyvinyl alcohol, starch, and cellulose resins. The bulky pulp sheet according to claim 1, wherein at least 5% by weight or less of at least one organic binder selected from water-soluble polymers is attached to the weight of the sheet. (3) Claim (1) wherein the cellulose pulp is fibrous or powdered softwood pulp, hardwood pulp, or waste paper pulp.
Or the bulky pulp sheet described in (2). (4) Eccentric core-sheath type or side pie-side type polyester composite fiber whose crimp form is three-dimensional crimp is 80 to 180°C
It has 30 or more spiral crimps per 25 mm when dry heated, the fineness is 0.5 to 15 denier, and the fiber length is 2 to 6.
The bulky pulp sheet according to claim (1), (2) or (3), which has a thickness of 0 mm. (5) The heat-fusion binder fiber is a synthetic fiber consisting of a single component selected from polyolefin, modified polyester, polyamide, and polyvinyl alcohol copolymer, or the sheath component is the above-mentioned polyolefin, modified polyester, polyamide, and polyvinyl alcohol copolymer. It is a composite fiber made of components selected from a combination, and its fineness is 1 to 6 deniers.
The bulky pulp sheet according to any one of claims (1) to (4), having a fiber length of 2 to 60 mm. (6) Cellulose pulp 40-90% by weight, eccentric core-sheath type or side pie-side type polyester composite fiber with a three-dimensional crimp form ●5-60% by weight and heat-fusible binder fiber 5-50% by weight A method for producing a bulky pulp sheet, which comprises laminating mixed fibers in which % is mixed and dispersed using a high-speed stirring mixer, and drying or heat-treating the fibers at 80 to 180°C. (7) At least one thermoplastic or thermosetting resin selected from polyolefin, polyvinyl acetate, acrylic, phenol, epoxy, vinyl chloride resin, polyvinyl alcohol, or starch resin for the mixed fiber. The manufacturing method according to claim 6, wherein at least one organic binder selected from cellulose-based water-soluble polymers is laminated on the net while being sprayed.