WO2004067825A1

WO2004067825A1 - Dry-process nonwoven pulp fabric composed of united layer structures

Info

Publication number: WO2004067825A1
Application number: PCT/JP2004/000108
Authority: WO
Inventors: Yasuji Yasumitsu; Yasuyuki Yamazaki; Shoji Nishigawa
Original assignee: Kinsei Seishi Co., Ltd.
Priority date: 2003-01-20
Filing date: 2004-01-09
Publication date: 2004-08-12
Also published as: CN1738934A; JP4225408B2; JP2004263307A; TWI324195B; KR101049623B1; KR20050096108A; US20060194498A1; TW200417644A

Abstract

A dry-process nonwoven pulp fabric composed of united layer structures, which comprises: a surface layer part, on each side, comprising heat-bondable synthetic fibers which have been heat-bonded to one another and having a basis weight of 5 to 12 g/m2, excluding 5 g/m2; and a core layer part comprising 20 to 60 wt.% heat-bondable synthetic fibers and 80 to 40 wt.% pulp fibers, the synthetic fibers having been heat-bonded to one another and/or the synthetic fibers and the pulp fibers having been heat-bonded to one another, and having a basis weight of 8 to 240 g/m2. The front and back surface layers and the core layer part as a whole also have been united by the heat bonding of the synthetic fibers to one another. The ratio of the fabric strength in the lengthwise direction to that in the cross direction is from 0.8 to 1.2 in each of a dry state and a wet state. The ratio of the fabric strength in a dry state to that in a wet state is from 0.6 to 1.1. The fabric further has a water absorption of 8 to 20 g/g and a total basis weight of 20 to 250 g/m2. The dry-process nonwoven pulp fabric obtained is free from fiber shedding, satisfactorily absorbs water, and has a high wet strength. It is hence suitable for use as a wiper, kitchen sheet, etc. which are used in a wet state.

Description

Description. Dry pulp nonwoven fabric with integrated layered structure

TECHNICAL FIELD The present invention relates to a dry pulp nonwoven fabric which is strong even when wet. In more detail, we use objective wipers for floors, kitchens, and cars used in wet conditions, kitchen sheets for cleaning utensils, wiping food, absorbing drip, face, hand, and body. The present invention relates to a nonwoven fabric suitable for personal wipers and the like. Furthermore, the present invention can be expected to have the same effect even when used in a dry form, since moisture is often present in these applications, and it can be used for sanitary materials such as sanitary products and diapers. The present invention also relates to a nonwoven fabric which is similarly suitable for medical use. Background art

Dry pulp nonwoven fabric known in the prior art, or sprayed or coated Kemi force Rupainda first resin in the surface layer of such Poriatariru acid ^¾ ester Ya polyvinyl acetate Bulle based pulp fiber layer as a base, or by impregnating the entire To form inter-fiber bonds.

In such a nonwoven fabric, when the binder amount is increased, the resin forms a film to become hard and the water absorption capacity is reduced, and when the binder amount is reduced, not only the pulp fiber is dropped off but also the strength is increased. A decrease in wet strength is inevitable.

A method of applying a powdery binder resin is also conceivable, but in this case, it is difficult to form a film, but the adhesion point between the pulp fiber and the binder is determined. The number decreases and the number of dropped fibers tends to increase. Therefore, it is difficult to produce a dry pulp nonwoven fabric that is excellent in wet strength while ensuring a feeling that is not too hard, a moderate water absorption, a small amount of fiber falling off, and a strength that can withstand practical use.

Dry a pulp nonwoven fabric, catamenial absorbent insert material Ya home Oh Rui as those used in the cleaning application for industrial, consists only of binding the fibers of the surface layer having a basis weight 1 to 5 g / m ² of A dry pulp nonwoven fabric in which the bonding fiber in the inner layer portion is 2 to 10% by weight has been proposed (Japanese Patent Application Laid-Open No. 2000-504792).

Regarding the strength of this non-woven fabric, although it is sufficient for use in sanitary products such as absorbent insert materials for sanitary products, the strength of ordinary nonwoven fabrics is not so great as to whether it is strong even when wet, which is a major point of the present invention. No mention was made. The nonwoven fabric of the technical content falling within the scope of this published patent has an inner layer having a binding fiber content of 2 to 10 weight. / ₀ , it is difficult to say that it is strong even when wet, and it causes a considerable decrease in strength when wet, and is not suitable for wiping, which is completely different from the intention of the present invention.

An air-laid nonwoven fabric having a specific tearing strength, which is formed by heat bonding the intersections of binder fibers, has also been proposed (Japanese Patent Application Laid-Open No. 2000-345454). There is no mention of the wet strength or water absorption when combined with the above, and there is no description suggesting the technology as a layered structure of the present invention.

The conventional nonwoven fabric has the above-mentioned problems. Disclosure of the invention

In view of the above situation, the present inventors have made intensive studies and as a result, optimized the basis weight of the front and back layers containing the heat-adhesive synthetic fiber, and The present inventors have found that by increasing the amount of the synthetic synthetic fibers, it is possible to obtain a dry nonwoven fabric that does not fall off the fibers, has good water absorption, and is strong, and particularly has a sufficient wet strength, and has completed the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention provides a thermoadhesive synthetic fiber, comprising a thermoadhesive synthetic fiber, wherein the synthetic fibers are heat bonded to each other, and have a basis weight of more than 5 g Zin ² and not more than 12 g Zm ^2. Pulp fiber is mixed at a ratio of 20 to 80% by weight, and the synthetic fiber and the pulp fiber are thermally bonded to each other. There consists inner layer portion is 8~2 4 0 g / m ^2, as a whole, between the front and rear surfaces and the inner layer portion also being integrated by thermal bonding of each other the synthetic fibers, strong vertical and ® co Is between 0.8 and 1.2 for both dry and wet conditions, the ratio of strength between dry and wet conditions is between 0.6 and 1.1, and the water absorption is 8 to 2 O g is / g, and wherein the total basis weight is ^{2 0~ 2 5 0 g Zm 2} , dry pulp nonwoven fabric layered structure are integrated (hereinafter, simply Also referred to as a dry nonwoven fabric ") on.

Hereinafter, embodiments of the present invention will be described.

The nonwoven fabric of the present invention has a three-layer structure of an inner layer made of a heat-adhesive synthetic fiber and a pulp fiber, and a surface layer containing the heat-adhesive synthetic fiber sandwiching the inner layer, and is integrated by heat bonding.

In the present invention, the thermoadhesive synthetic fibers which are the main component forming the surface layer or mixed with the pulp may be any as long as they are melted by heat and bonded to each other. The pulp is fixed in a network structure by bonding, and fibers using a polymer having a high affinity for pulp fibers are particularly preferable. For example, polyolefins, unsaturated Examples include polyolefins grafted with carboxylic acids, polyesters, and polybutyl alcohol.

Among them, as the polyolefin-based thermoadhesive synthetic fiber, a core-sheath type or an eccentric side-by-side type composite fiber is preferable. Examples of the polyolefin that forms the sheath or the outer periphery of the fiber include polyethylene and polypropylene. As the polymer constituting the core component or the fiber inner layer, a polymer having a higher melting point than the sheath and not changing at the temperature of the heat bonding treatment is preferable. Such combinations include, for example, polyethylene / polypropylene, polyethylene / polyester, polypropylene / polyester, and the like. These polymers may be modified as long as the effects of the present invention are not impaired. Furthermore, fibril-like fibers may be used. For example, SWP of Mitsui Chemicals, Inc. and the like can be mentioned.

If the heat-bondable synthetic fiber is thin, the number of constituent fibers increases, so the number of dropped fibers decreases and the texture becomes soft. If it is thick, the voids between the fibers will be large, resulting in a bulky nonwoven fabric, and a stripping effect can be expected. Accordingly, the thickness of the fiber may be selected according to the application, but the preferred fineness is 0.5 dt to 50 dt, and more preferably 0.5 dt.

8 dt to 30 dt. If it exceeds 50 dt, it is not preferable because pulp shedding cannot be suppressed. On the other hand, if it is less than 0.5 dt, the productivity of the nonwoven fabric is lacking, so that it is not practical.

Further, the length of the heat-adhesive synthetic fiber is preferably from 1 to 15 mm. If the fibers are short, the mixing with the pulp becomes better and a more uniform nonwoven fabric is easily formed, but if it is less than 1 mm, it becomes powdery, making it difficult to form a mesh structure due to inter-fiber bonding, making it impossible to prevent pulp from falling off It is not preferable because the strength and strength of the nonwoven fabric are reduced, and the practicability is lacking. While 1 If the length is longer than 5 mm, the strength of the nonwoven fabric is increased, but the fibers are apt to be entangled in pneumatic transportation of the nonwoven fabric at the time of production, which is not preferred because the fiber mass defect increases. Particularly preferred is 3 to 10 mm.

On the surface layer, in addition to the above-mentioned heat-adhesive synthetic fibers, recycled fibers such as rayon, semi-synthetic fibers such as acetate, synthetic fibers such as polyester, polypropylene, polyamide, and vinylon, pulp, cotton, hemp, etc. Other fibers such as natural fibers of the present invention may be included. In this case, the proportion of the heat-adhesive synthetic fiber in the surface layer is preferably 70 to 100% by weight, and more preferably 85 to 100% by weight. If the content is less than 70% by weight, the other fibers mentioned above are likely to fall off, and the effect of suppressing the falling off of the pulp in the inner layer is reduced. Occurs.

These fibers forming the surface layer are thermally bonded, and the pulp is fixed in a network structure by the inter-fiber bonds. Weight per unit area must be 1 ² gZm 2 below by more than 5 _g Zm ^2. At S gZm ² or less, the amount of synthetic fibers having water resistance and the number of bonding points between the fibers are small, so that it is not possible to ensure a sufficient wet strength enough to withstand wiping, so that the number of fibers falling off tends to increase. Unlike applications that emphasize absorbency, such as sanitary materials, fibers tend to fall off when used for wiping, and such nonwoven fabrics are not practical for applications such as wipers and kitchen sheets. On the other hand, if it exceeds 12 g / m 2, the water-resistant heat-bonding layer becomes too thick, the water absorption into the inner layer becomes insufficient, and the texture becomes hard, which is also lacking in practicality . As the basis weight increases, the strength increases but the water absorption decreases. However, within the scope of the present invention, it is possible to obtain a nonwoven fabric which has sufficient water absorption, has strength even when wet, has no fibers falling off, and has a soft texture. PT / JP2004 / 000108

6

In addition, since the amount of synthetic fiber is large, oil absorption is good, and it is well compatible with oil, so there is an advantage that dirt is easily removed.

In the inner layer, the heat-adhesive synthetic fiber and the pulp fiber are integrated by heat bonding. The same or different thermoadhesive synthetic fibers may be used as the surface layer. As the pulp fiber, a ground pulp having a length of 0.2 mm to 5 mm is preferable.

As for the mixing ratio of the heat-adhesive synthetic fiber and the pulp fiber in the inner layer portion, if the ratio of the heat-adhesive synthetic fiber is less than 20% by weight of the total of the adhesive synthetic fiber and the pulp fiber, the dropped fibers increase. The strength, especially when wet, is reduced. Although such a material can be used for applications that do not have strength but emphasize water absorption and softness, such as sanitary products, it can be used as a nonwoven fabric for wiping, which is the object of the present invention. I can't stand it. On the other hand, if it exceeds 60% by weight, the amount of pulp fibers contributing to the absorption is reduced, the water wiping properties and the absorption are not only poor, but the strength is also hard and the practicality is poor.

As the ratio of the heat-bondable synthetic fiber increases, the strength increases, but the water absorption decreases.

Therefore, it was difficult to achieve both sufficient strength, especially when wet, and water absorption.

For wipers and kitchen sheets, balancing these is very important. Only when the ratio is within the range according to the present invention, a nonwoven fabric having sufficient water absorbency and sufficient strength even when wet can be obtained. In addition, the amount of the dropped fibers is small, and such a nonwoven fabric has sufficient strength to be washed, squeezed and dried even if it becomes dirty, and can be used several times. In addition, since the ratio of thermosynthetic fibers is large, the bulk is small and it can be made thin, so that it has excellent handling properties and saves energy. Also useful for space.

In the inner layer, the heat-adhesive synthetic fibers and the heat-adhesive synthetic fibers and the pulp fibers are heat-bonded. Basis weight of the inner layer 8~ ² 4 0 gZm 2 is preferred. If it is less than 8 gZm ² , the amount of pulp is too small and the water absorption is insufficient. On the other hand, if it exceeds 24 Og / m ² , the whole becomes plate-like and is not suitable for this application.

Further, the entire nonwoven fabric is also integrated between the front and back surfaces and the inner layer portion by heat bonding of the heat-bondable synthetic fibers. Furthermore, it has sufficient heat sealing properties.

Such a nonwoven fabric may be manufactured by any method as long as it is a dry nonwoven fabric, but a nonwoven fabric formed by an airlaid method is preferable. Nonwoven fabrics manufactured by the airlaid method are preferred because the fibers forming the nonwoven fabric are randomly and three-dimensionally oriented in the longitudinal, width and thickness directions of the nonwoven.

Here, the nonwoven fabric by the airlaid method can be obtained as follows.

A predetermined amount of defibrated heat-adhesive synthetic fibers are transported while being uniformly dispersed in the airflow, and the fibers blown out from a screen having pores provided in the discharge section are installed at the bottom. The fiber is deposited on the net while dropping it on a metal or plastic net that has been dropped and sucking air at the bottom of the net. Next, a mixture of the heat-adhesive synthetic fiber and the pulp fiber is similarly deposited on the above-mentioned deposition sheet. Further, fibers mainly composed of thermo-adhesive synthetic fibers are deposited on these sheets.

Next, the whole is heat-treated to a temperature at which the heat-adhesive synthetic fiber sufficiently exhibits its adhesive effect, whereby the dry pulp nonwoven fabric of the present invention can be obtained. In order to sufficiently exhibit the bonding effect, a heat treatment at a temperature higher by 15 to 40 ° C than the melting point of the bonding component of the heat-bondable synthetic fiber is necessary.

Thus, the nonwoven fabric manufactured by the airlaid method can randomly orient the fibers three-dimensionally in the flow direction, width direction, and thickness direction of the nonwoven fabric. Since these are thermally bonded, delamination does not occur. In addition, nonwoven fabrics manufactured by the airlaid method have good uniformity, so that the dispersion in performance is reduced.

If necessary, further calendering or embossing can be applied.

In the nonwoven fabric of the present invention, the ratio of the strength of warp to the width must be 0.8 to 1.2, preferably 0.85 to 1.2, both when dry and when wet. If one of the strengths is low, practical problems are likely to occur. Also, the ratio of strength between dry and wet should be 0.6-1.1, preferably 0.7-1.1. A nonwoven fabric having a strength of less than 0.6 greatly reduces wet strength compared to dryness, that is, weakens when wetted, which deviates from the intended purpose of the present invention and causes practical problems. Also, when wet, the strength increases due to the surface tension between the fibers due to the presence of moisture, which may exceed 1, which is also within the scope of the present invention. It is not usually more than one.

Wipers, kitchen sheets, sanitary materials, and the like to which the nonwoven fabric of the present invention is applied need to have an appropriate water absorbing property, and the water absorbing property is 8 to 2 OgZg, preferably 10 to : 18 g Z g must be. If it is less than 8 g / g, the wiping property and the water retention property in practical use are lacking, and there is a problem in practical use. On the other hand, if it exceeds 20 g / g, the amount of moisture retained by the nonwoven fabric itself is too large, and there is a problem in handleability. The basis weight of the whole nonwoven fabric is preferably ^{2 0~2 5 0 g / / m} , depending on APPLICATIONS, it is possible to select an appropriate basis weight.

The nonwoven fabric of the present invention may be integrated with other sheets as long as the intention of the present invention is not impaired. For example, if it is to be integrated with a breathable sheet, the nonwoven fabric of the present invention can be easily formed into a composite sheet by placing the breathable sheet on a wire mesh and depositing fibers on the wire mesh. be able to.

Examples of the sheet to be integrated include commonly known dry nonwoven fabric, wet nonwoven fabric, paper, spunbond, melt-pro, plastic net, perforated film, split yarn cloth, coarse woven knitted fabric, and cold gauze. However, a sheet made of a heat-adhesive material is preferable, and the air permeability is preferably high.

According to the present invention, the basis weight of the front and back layers containing the heat-adhesive synthetic fibers is optimized, and the amount of the heat-adhesive synthetic fibers in the inner layer is increased, so that the fibers are prevented from falling off and the non-woven fabric is not impaired. It has become possible to increase the strength of the product to withstand wet use and repeated use. In addition, water and oil wiping properties were good, there was no delamination, and a nonwoven fabric very suitable for wiping applications could be obtained. Further, the nonwoven fabric of the present invention has a sufficient heat sealing property. It is also suitable for sanitary products, sanitary materials such as diapers, and medical applications.

In addition, the nonwoven fabric of the present invention has no concern about residual monomer due to the chemical binder resin, and is hygienic.o

Furthermore, no wastewater is produced during the nonwoven fabric manufacturing process, and there is no chemical piner monomer in the exhaust air, so the environmental load is small. Example The present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1

A core-sheath composite fiber (Teijin Fiber Co., Ltd.'s F6.2.2 dt, length 5 mm) with a core of polyethylene terephthalate and a sheath of polyethylene is used as the heat-adhesive fiber for the front and back layers. Is a composite fiber with a core of polypropylene and a sheath of copolymerized polyethylene (Nisso Polypro Fiber Co., Ltd., Intac. 1.7 dt, length 5 mm) and pulp (W eyerhaeuser * NB 4 16 K raft) ) Were mixed at a ratio of 30% by weight and 70% by weight, respectively, and the nonwoven fabric was manufactured by an air laid method at a heating temperature of 144 ° C.

The weight of the front and back layers was 6 g / m ² , and the weight of the inner layer was 33 g / m ² . The thickness was 0.54 mm.

Table 1 shows the properties of vertical and horizontal strengths, their ratios, their ratios when dry and wet, and their water absorption.

The strength and water absorption were measured by the following methods.

(1) Strong: According to JISL—1913. However, the width of the test piece was 25 mm, and the grip distance was 100 mm.

(2) Water absorption: A 100 mm x 100 mm test piece, which was previously weighed, was immersed in water at 20 ° C for 1 minute, and then placed on a glass plate inclined at 45 degrees. Leave for 1 minute, then weigh again and calculate the water absorption by the following formula.

① area per absorbent (gZm ^2): the weight of the water-absorbing water, divided by the area of the test piece, displayed as g / m ^2.

(2) Water absorption per own weight (g / g): Divide the weight of the absorbed water by the weight of the test piece and display as g / g. P2004 / 000108

11 Example 2

Front and back layers of the adhesive composite fibers and a ratio of 9 0 1 0 pulp, the attached eye 8 g Zm ^2, the ratio of the adhesive composite fibers and pulp of the inner layer portion 2 5/7 5, 4 basis weight 9 g / A non-woven fabric was manufactured by the air laid method in the same manner as in Example 1 except that m ² was used.

The thickness was 0.68 mm.

Example 3

Air-laid in the same manner as in Example 1 except that the basis weight of the front and back layers was 10 g / m ² , the ratio of the adhesive conjugate fiber to pulp in the inner layer was 40/60, and the basis weight was 100 gZm ^2. Nonwoven fabric was manufactured by the method.

Comparative Example 1

Front and back layer portions 4 a basis weight of g / m ^2, the ratio of the adhesive composite fibers and pulp of the inner layer portion 8/9 2, except that the basis weight and 5 2 g / m ² is in the in Example 1 and same as Nonwoven fabric was manufactured by the airlaid method.

Comparative Example 2

The air laid method was the same as in Example 1 except that the basis weight of the front and back layers was 16 gZm ² , the ratio of the adhesive conjugate fiber to pulp in the inner layer was 70/30, and the basis weight was 23 g / m ^2. Produced a nonwoven fabric.

Comparative Example 3

An air-laid nonwoven fabric made of only pulp with a basis weight of 58 g Zm ² was prepared, and impregnated with emulsion of polyacrylic acid ester resin at a solid content of 8 g / m ^2, and hot air temperature was 130 The resin was dried at ° C to form a resin-type air-laid nonwoven fabric.

Table 1 shows the physical properties of the nonwoven fabrics obtained in the above Examples and Comparative Examples. PT / JP2004 / 000108

12

【table 1 】

Item Example Example Example Example Comparative example Comparative example Comparative example

1 2 3 1.2.3 Composition PET / PE duplex 100% 90% 100% 100% 100% Atari synthetic fiber resin (2.2 dt X 8g / surface 5mm) 2

m, pulp 10% — — Nonorep

55g / nf Weight g / m ² 6 8 10 4 16

Composition PP / PE double 30% 25% 40% 8% 70%

Uchigo Fiber

(1.7dt X

5mm)

Pulp 70% 75% 60% 92% 30% Weight g / m 33 49 100 52 32

Weight (g / m ² ) 45 65 120 60 55 63 Thickness (mm) 0.54 0.68 1.30 0.78 0.50 0.73 5.15.07.9 Non (N / 25mm 9.9.9.0 33.8 4.7.15.2.0 weave) Ratio 0.88 0.97 0.98 0.92 1. 01 0. 76

(Hoko

object

ι, ιΐ. / vertical)

'] ±'

Wet strong vertical 9.0 0 7. 9 31. 2 2. 3 14. 8 3.1

(N / 25mra 33 9.2 7.5 30.8 1.9 15.0 2.5

) Ratio 1.02 0.95 0.99 0.83 1.01 0.81

(Cho 3

/ Vertical)

Wet and wet wet 0.80 0.85 0.90 0.45 0.99 0.39 Ratio (Ta / Ni

Te) 4

Water absorption g / m 538 790 1080 960 385 882 g / g 12.0 12.2 9.0 0 16 7 14 Industrial applicability

The dry pulp nonwoven fabric having the layered structure integrated according to the present invention is used for an object-type wiper for floors, kitchens, automobiles, etc., used for cleaning, cooking utensils cleaning, food wiping, drip absorption, etc. It is suitable for use on kitchen seats, personal wipers such as faces, hands, and bodies. Further, it is similarly suitable for sanitary products, sanitary materials such as diapers, and medical applications.

Claims

The scope of the claims

1. includes a thermal bonding synthetic fiber, and the surface layer portion of the duplex the synthetic fibers with each other is the basis weight is heat bonding 5 gZm ² a 1 ² gZm 2 or less than, and the heat-adhesive synthetic fibers and pulp fibers 20 / 80~60Z40 have been engaged mixed at a ratio of weight percent, it consists that the said synthetic fibers to each other and Roh or synthetic fibers and pulp textiles is thermally bonded, the basis weight is at 8~240 g / m ² It consists of an inner layer, and as a whole, the front and back surfaces and the inner layer are also integrated by the thermal bonding of the synthetic fibers, and the strength ratio of vertical and horizontal is wet when dry. At all times, it is 0.8 to 1.2, the ratio of strength between dry and wet is 0.6 to 1.1, the water absorption is 8 to 20 g / g, and the total basis weight is characterized by a 20~250 gZm ^2, dry pulp nonwoven fabric layered structure are integrated.