KR101049623B1 - Dry pulp nonwoven fabric with integrated layer structure - Google Patents

Abstract

20/80 to 60 / of the surface layer portions on both sides including heat-adhesive synthetic fibers, wherein the synthetic fibers are heat-bonded, and the basis weight is more than 5 g / m 2 and not more than 12 g / m 2. It consists of the inner-layer part of 8-240 g / m <2> of the basis weight which the synthetic fiber and / or the synthetic fiber and the pulp fiber heat-bonded in the ratio of 40 weight%, and also the said synthetic fiber between the front and back surface and the inner layer part as a whole It is integrated by thermal bonding of each other, the ratio of longitudinal and transverse strength is 0.8 to 1.2 in both drying and wetting, the ratio of strength in drying and wetting is 0.6 to 1.1, and the water absorption is It is a dry pulp nonwoven fabric having a layered structure of 8 to 20 g / g and a total basis weight of 20 to 250 g / m 2. The resulting dry pulp nonwoven fabric is free of fibers, has good water absorbency, has high wet strength, and is suitable for wipers, kitchen sheets, and the like used in a wet state.

Nonwovens, Pulp, Dry, Layered, Integral

Description

DRY-PROCESS NONWOVEN PULP FABRIC COMPOSED OF UNITED LAYER STRUCTURES}

The present invention relates to a dry pulp nonwoven fabric that is wet even strong. More specifically, kitchen sheets such as floor wipers used in a wet state, kitchen wipers, etc., kitchen utensils for cleaning cooking utensils, cleaning food, and absorbing drip coffee. The present invention relates to a nonwoven fabric suitable for adult wipers such as hand, body, and the like. In addition, even when used in a dry state, the present invention can be expected to have the same effect because water is often present in such applications, and the same suitable non-woven fabric is also suitable for sanitary materials such as sanitary products, diapers, and medical applications. It is about.

BACKGROUND ART Conventionally known dry pulp nonwoven fabrics form a fiber-to-fiber bond by spraying, applying, or impregnating a chemical binder resin, such as polyacrylic ester or polyvinyl acetate, onto the surface layer, based on the pulp fiber layer.

In such a nonwoven fabric, increasing the amount of the binder causes the resin to form a film to harden or cause a decrease in the water absorption capacity, and furthermore, not only increases the dropping of the pulp fibers, but also increases the strength, especially when wet. Deterioration of power is inevitable.

Moreover, although the method of giving a powdery binder resin is also considered, in this case, although a film is difficult, the number of adhesion points of a pulp fiber and a binder becomes small, and a fallout fiber tends to increase. Therefore, it is difficult to make a dry pulp nonwoven fabric having excellent wet strength while ensuring a texture that is not too hard, adequate water absorption, low fiber dropping, and strong strength to withstand practical use.

It is a dry pulp nonwoven fabric and is used for absorbent inserts for sanitary products or for cleaning applications for home or industrial use, and has a basic weight of 1 to 5 g / m 2 and a combined fiber of the inner layer at 2 to 5 g / m 2. A dry pulp nonwoven fabric of 10% by weight is proposed (JP-A No. 2000-504792).

Regarding the strength of this nonwoven fabric, it can be said that the general strength is sufficient for use of hygiene products such as absorbent inserts of sanitary products, and it is not mentioned at all about the wet point which is a big point of the present invention. not. The nonwoven fabric of the technical content falling within the scope of this disclosure is less than 2 to 10% by weight of the binding fiber in the inner layer, hardly to be wet, and causes very strong deterioration when wet, and is difficult to wipe off. It is not suitable and is completely different from the intention of the present invention.

In addition, air-laid nonwoven fabrics having a particular tear strength, which are formed by thermally bonding the intersection points of binder fibers, have also been proposed (see Japanese Patent Application Laid-Open No. 2000-345454), but they are composited with pulp. In this case, there is no reference to the wet strength or the absorbency, and there is no description suggesting the technique as the layered structure of the present invention.

The conventional nonwoven fabric had the above problems.

In light of the above-described phenomena, the inventors of the present invention have conducted diligent studies to optimize the basis weight of the front and back layer including the heat-adhesive synthetic fibers and to increase the amount of the heat-adhesive synthetic fibers in the inner layer. It has been found that a dry nonwoven fabric can be obtained without falling off, having good water absorbency, and having sufficient strong, particularly wet strength, and has completed the present invention.

The present invention includes a heat-adhesive synthetic fiber, the synthetic fibers are heat-bonded, the surface layer portion of both sides having a basis weight of more than 5g / ㎡ 12g / ㎡ or less, heat-adhesive synthetic fibers and pulp fibers 20/80 ~ It is mixed at a ratio of 60/40% by weight, and the synthetic fibers and / or synthetic fibers and pulp fibers are heat-bonded, and composed of an inner layer having a basis weight of 8 to 240 g / m 2, and the front and back surfaces as a whole. The synthetic fibers are also integrated between the inner and inner layers by thermal bonding, and the ratio of longitudinal and transverse strength is 0.8 to 1.2 in both drying and wetting, and the ratio of strength in drying and wetting is 0.6. Dry pulp nonwoven fabric (hereinafter referred to simply as &quot; dry nonwoven fabric &quot;) having a layered structure characterized by having a water absorption of 8 to 20 g / g and a total basis weight of 20 to 250 g / m2. It is about.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

The nonwoven fabric of this invention consists of a 3-layered structure which consists of an inner layer which consists of a heat-adhesive synthetic fiber and a pulp fiber, and the heat-adhesive synthetic fiber which sandwiches it, and is integrated by heat bonding.

In the present invention, any of the heat-adhesive synthetic fibers, which are the main components forming the surface layer or mixed with the pulp, may be any ones as long as they are melted by heat and bonded to each other, and have a mesh-like structure by the inter-fiber bonding. Although pulp is fixed, fibers using a polymer having a high affinity with pulp fibers are particularly preferred. For example, polyolefins grafted with polyolefins and unsaturated carboxylic acids, polyesters, polyvinyl alcohol, etc. are mentioned.

Among them, sheath-core type or eccentric side-by-side type composite fibers are suitable as the polyolefin-based heat-adhesive synthetic fibers. Examples of the polyolefin constituting the sheath or fiber outer periphery include polyethylene and polypropylene. As the polymer constituting the core or the fiber inner layer, a polymer having a higher melting point than the sheath and which does not change at the heat adhesion treatment temperature is preferable. Examples of such knitting include polyethylene / polypropylene, polyethylene / polyester, polypropylene / polyester, and the like. Such a polymer is not impaired even if it is modified in a range that does not impair the action and effect of the present invention. Fibril-like fibers may also be used. For example, SWP of Mitsui Chemicals, Inc. is mentioned.

Since the heat-adhesive synthetic fiber is thinner, the number of constituent fibers increases, so that there is less dropout fiber and the feel is soft. In the thick case, the space | gap between a fiber becomes large, it becomes a bulky nonwoven fabric, and a scraping effect can also be anticipated. Therefore, although the thickness of a fiber may be selected according to a use, preferable fineness is 0.5dt-50dt, More preferably, it is 0.8dt-30dt. If it exceeds 50dt, the fallout of the pulp is not suppressed, which is not preferable. On the other hand, if it is less than 0.5dt, productivity of a nonwoven fabric is lacking and it is not practical.

In addition, the length of the heat-adhesive synthetic fiber is preferably 1 to 15 mm. The shorter the fiber, the better the admixture with the pulp and the more easily the non-woven fabric becomes, but if it is less than 1 mm, it will be closer to the powder phase, making it difficult to form a mesh structure by the fiber-to-fiber bonding, and it will not be possible to prevent the pulp from falling off. However, since the strength as a nonwoven fabric is low and practicality is inferior, it is not preferable. On the other hand, when it is longer than 15 mm, the strength of the nonwoven fabric increases, but it is not preferable because the fibers tend to get entangled in the air transport of the fibers at the time of manufacturing the nonwoven fabric, thereby increasing the defects of the fiber mass. Especially preferred is 3-10 mm.

In addition to the above-mentioned heat-adhesive synthetic fibers, surface fibers include regenerated fibers such as rayon, semisynthetic fibers such as acetate, synthetic fibers such as polyester, polypropylene, polyamide, and vinylon, and natural fibers such as pulp, cotton, and hemp. It may contain a fiber. In this case, the ratio of the heat-adhesive synthetic fiber in the surface layer is preferably 70 to 100% by weight, more preferably 85 to 100% by weight. In the case of less than 70% by weight, not only the dropping of the other fibers is more likely to occur, but also the effect of suppressing the dropping of the pulp in the inner layer is less, and the wet strength is also lowered, resulting in practical problems.

These fibers forming the surface layer are heat bonded, and the pulp is fixed to the network structure by the interfiber bonding. The basis weight must exceed 12 g / m <2> exceeding 5 g / m <2>. At 5 g / m 2 or less, since the amount of synthetic fibers having water resistance and the number of bonding points between the fibers are small, not only sufficient wet strength to withstand wiping can be secured, but also it is easy to cause an increase in dropping fibers. Unlike the use which emphasizes absorbency like a hygiene material, when used for wiping off, a fiber is easy to fall off, and such a nonwoven fabric is not practical for use, such as a wiper and a kitchen sheet. On the other hand, if it exceeds 12 g / m 2, the water-resistant heat-adhesive layer becomes too thick to insufficiently absorb water into the inner layer, and the texture is also hard, which is also insufficient in practicality. The higher the basis weight, the higher the strength, but the lower the absorbency. However, if it is the scope of the present invention, it is possible to obtain a nonwoven fabric having sufficient absorbency and strength even when wet, without falling off of fibers and having a soft touch.

In addition, since the amount of synthetic fibers is large, the absorption of oil is good and the affinity with the oil component is also good, and there is also an advantage that dirt tends to fall.

The inner layer portion is heat-bonded synthetic fibers and pulp fibers are integrated by heat bonding. The heat-adhesive synthetic fiber may use the same thing as the surface layer, or may use another. As pulp fiber, the grinding pulp of 0.2 mm-5 mm in length is preferable.

The mixing ratio of the heat-adhesive synthetic fiber and the pulp fiber in the inner layer portion is such that when the ratio of the heat-adhesive synthetic fiber is less than 20% by weight relative to the total of the adhesive synthetic fiber and the pulp fiber, the dropping fibers increase and the strength, in particular, when wet Strength decreases. Such materials may be used as nonwoven fabrics for wiping, which is the object of the present invention, even if they can be used for applications that emphasize absorptivity and softness even without strength. On the other hand, if it exceeds 60% by weight, the amount of pulp fibers contributing to the water absorbency decreases, the wiping property and the water absorptivity of the water are insufficient, the texture is also hard, and the practicality is insufficient.

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

Therefore, sufficient strength, in particular, both the strength and the absorbency at the time of wetness were difficult.

This compatibility is very important for the use of wipers and kitchen sheets. Within the range of the ratio of the present invention, a nonwoven fabric having sufficient 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 a strength sufficient to be washed and dried even if it is dirty, and can be used repeatedly several times. In addition, since the ratio of the heat-adhesive synthetic fiber is large, the volume is small and the thickness can be made thin, so the handling property is excellent and the space is also conducive.

In the inner layer, heat-adhesive synthetic fibers and heat-adhesive synthetic fibers and pulp fibers are heat-bonded. As for the basis weight of this inner layer, 8-240g / m <2> is preferable. If it is less than 8 g / m <2>, the quantity of pulp is too small and water absorption is insufficient, On the other hand, when it exceeds 240 g / m <2>, the whole will show plate shape and it is not suitable for this use.

Moreover, the whole nonwoven fabric is also integrated between the front and back surface and an inner layer part by the thermal bonding of heat-adhesive synthetic fibers. It also has sufficient heat seal.

Such a nonwoven fabric may be produced by any method as long as it is a dry nonwoven fabric, but a nonwoven fabric by an air-laid method is preferable. The nonwoven fabric produced by the airlaid method is preferable because the fibers forming the nonwoven fabric are randomly three-dimensionally oriented in the longitudinal direction, the width direction, and the thickness direction of the nonwoven fabric.

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

The fibers mainly composed of a predetermined amount of decomposed heat-adhesive synthetic fibers are conveyed while being uniformly dispersed in an air stream, and blown from a screen having pores provided in the discharge portion. The fiber thus produced is dropped on a metal or plastic net provided in the lower part, and the fiber is deposited on the net while inhaling air from the lower part of the net. Next, a mixture of heat-adhesive synthetic fibers and pulp fibers is made identical and deposited on the deposition sheet. In addition, fibers mainly composed of heat-adhesive synthetic fibers are deposited on these sheets.

Next, the whole pulp nonwoven fabric of this invention can be obtained by heat-processing the whole at the temperature which this heat adhesive synthetic fiber fully exhibits the adhesive effect. In order to fully exhibit the adhesive effect, heat treatment is required at a temperature of 15 to 40 ° C. higher than the melting point of the adhesive component of the heat-adhesive synthetic fiber.

In this way, the nonwoven fabric produced by the airlaid method can randomly orient the fibers in the longitudinal direction, the width direction, and the thickness direction of the nonwoven fabric. And since these are heat bonded, they do not cause delamination. In addition, the nonwoven fabric produced by the airlaid method has a good uniformity, and the performance imbalance is also reduced.

If needed, you can also do calendaring or embossing.

The nonwoven fabric of the present invention should have a longitudinal and transverse strength ratio of 0.8 to 1.2, preferably 0.85 to 1.2, both in drying and in wet. When either one of the strengths is low, practical problems are likely to occur.

In addition, the ratio of the strength at the time of drying and the humidity must be 0.6 to 1.1, preferably 0.7 to 1.1. The thing less than 0.6 greatly reduces the strength at the time of wet compared with the time of drying. That is, it is a nonwoven fabric which becomes weak when wet, and a problem arises practically beyond the intention of this invention. In addition, when wet, strength may increase due to the surface tension between fibers due to the presence of water, which is more than 1, which is also the scope of the present invention, but 1.1 is used unless other means for bonding in the presence of water exist. There is usually nothing to go beyond.

Wipers, kitchen sheets, gastric materials, etc. to which the nonwoven fabric of the present invention is applied require proper water absorption, and the water absorption is not in the range of 8 to 20 g / g, preferably 10 to 18 g / g. Can not be done. If it is less than 8 g / g, there is a problem in practical use, lacking the wiping property and water storage retention property in practical use. On the other hand, when it exceeds 20 g / g, there is too much moisture amount which the nonwoven fabric itself maintains, and there exists a problem in handling handling property.

As a basis weight of the whole nonwoven fabric, 20-250 g / m <2> is preferable and a suitable basis weight can be selected according to a use.

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

In addition, as the sheet to be integrated, a dry nonwoven fabric, a wet nonwoven fabric, a paper, a spun-bond nonwoven fabric, a melt-blown nonwoven fabric, which is generally known, a plastic net, a perforated film, and a split yarn cloth yarn cloth, a loose knit fabric, a cold yarn, and the like, but a sheet made of a heat-adhesive material is preferred, and a higher air permeability is more preferable.

The present invention optimizes the basis weight of the front and back layer including the heat-adhesive synthetic fibers and increases the amount of the heat-adhesive synthetic fibers in the inner layer, thereby suppressing the dropping of the fibers and not impairing the absorbency, thereby increasing the strength of the nonwoven fabric. Can be raised to withstand the use of wet or repeated use. In addition, it was possible to obtain a nonwoven fabric which is well suited for wiping with water and oil, without interlayer peeling, and suitable for wiping applications. In addition, the nonwoven fabric of the present invention has sufficient heat seal. Moreover, it is similarly suitable also for sanitary materials, such as a sanitary goods and a diaper, and a medical use.

Moreover, the nonwoven fabric of this invention is hygienic, without worry of residual monomer by chemical binder resin.

In addition, in the manufacturing process of a nonwoven fabric, wastewater does not come out, exhaust gas does not have the monomer of a chemical binder, and environmental load is small.

Although an Example demonstrates this invention, this invention is not limited to this Example.

Example 1

Sheath-core type composite fiber whose core is polyethylene terephthalate and the sheath is polyethylene, as the heat-adhesive fiber of the front and back layer part (made by Teijin Fiber Co., Ltd., F6.2.2dt, length) 5 mm) and a composite fiber (Nitrogen Polypropylene Fiber Co., Inc .; 1.7dt, 5 mm in length) and pulp (made by Weyerhaeuser) whose core is polypropylene and sheath is copolymerized polyethylene. NB416 Kraft) was mixed at a ratio of 30% by weight and 70% by weight, respectively, and a nonwoven fabric was produced by an airlaid method with a heating temperature of 145 ° C.

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

Table 1 shows physical properties such as longitudinal strength, ratio, dry and wet ratio, water absorption, and the like.

In addition, strongness and water absorption were measured by the following method.

(1) Strongness: It depends on JIS # L-1913. However, the width of the test piece was 25 mm and the holding interval was 100 mm.

(2) Absorbency: The test piece of 100 mm x 100 mm which measured the weight in advance is immersed in 20 degreeC water for 1 minute, and it puts on the glass plate inclined at 45 degree | times for 1 minute, and after that, the weight is measured again and water absorption is carried out as follows. Calculate.

① Absorbency per area (g / m²): The weight of absorbed water is divided by the area of the test piece and expressed as g / m2.

② Absorbency per self weight (g / g): The weight of absorbed water is divided by the weight of the test piece and expressed as g / g.

Example 2

All except the ratio of adhesive composite fibers and pulp at the front and back layers at 90/10, the basis weight at 8 g / m 2, the ratio of the adhesive composite fibers and pulp at the inner layer at 25/75, and the basis weight at 49 g / m 2. A nonwoven fabric was produced in the same manner as in Example 1 by the airlaid method.

The thickness was 0.68 mm.

Example 3

Nonwoven fabrics were prepared 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 composite fibers and pulp of the inner layer was 40/60, and the basis weight was 100 g / m 2. did.

Comparative Example 1

Nonwoven fabrics were produced in the same manner as in Example 1 except that the basis weight of the front and back layers was 4 g / m 2, the ratio of the adhesive composite fibers and pulp of the inner layer was 8/92, and the basis weight was 52 g / m 2. did.

Comparative Example 2

A nonwoven fabric was produced in the same manner as in Example 1 except that the basis weight of the front and back layers was 16 g / m 2, the ratio of the adhesive composite fiber and pulp of the inner layer was 70/30, and the basis weight was 23 g / m 2. did.

Comparative Example 3

Prepare an airlaid nonwoven fabric made of pulp only with a basis weight of 58 g / m 2, impregnating an emulsion of polyacrylic acid ester resin to 8 g / m 2 as a solid content, and drying it at a hot air temperature of 130 ° C. to a resin-type airlaid nonwoven fabric. It was.

Table 1 shows the physical properties of the nonwoven fabric obtained in the above Examples and Comparative Examples.

The dry pulp nonwoven fabric incorporating the layered structure of the present invention is an object wiper for floors, kitchens, automobiles, etc. used in a wet state, cleaning of cooking utensils, cleaning of foodstuffs, and drip coffee. It is suitable for kitchen sheets such as absorption and adult wipers such as face, hands and body. Moreover, it is similarly suitable also for sanitary materials, such as a sanitary goods and a diaper, and a medical use.

Claims (1)

20/80 to 60/40, wherein the surface layer portions on both sides including heat-adhesive synthetic fibers, which are heat-bonded with each other and whose base weight is more than 5 g / m 2 and 12 g / m 2 or less, and heat-adhesive synthetic fibers and pulp fibers It is mixed by the ratio of weight%, the said synthetic fiber is heat-bonded, or the synthetic fiber and the pulp fiber are heat-bonded, and consists of an inner layer part with a basis weight of 8-240g / m <2>, and double-sided as a whole Between the surface layer portion and the inner layer portion of is also integrated by thermal bonding of the synthetic fibers, the ratio of longitudinal and transverse strength is 0.8 to 1.2 in both drying and wetting, the ratio of strength in drying and wetting. The dry pulp nonwoven fabric with a layered structure characterized by the above-mentioned. It is 0.6-1.1, water absorption is 8-20g / g, and a total basis weight is 20-250g / m <2>.