JPH04327256A - Stretchable nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain the subject nonwoven fabric, having specific extension recovery ratio, compressive bending resistance and apparent density value and excellent in stretchability, flexibility, etc., by using polypropylene-based crimped fiber and heat bonding fiber and providing dot fused areas and nondot fused areas. CONSTITUTION:(A) Polypropylene-based crimped fiber composed of two components having different melting points is blended with (B) heat bonding fiber composed of two components of a component (e.g. polyethylene) having a lower melting point than that of the low-melting component in the component (A) and a component (e.g. polypropylene) having a higher melting point than that at 100:(5-400) ratio by pts.wt. and >=6% of the whole area of the nonwoven fabric is dot fused by melting and solidifying. The others are formed into a nondot fused area to crimp the blended fiber with heat. Thereby, the objective nonwoven fabric having >=25% extension recovery ratio at 30% extension for both the longitudinal and transverse directions, <=80g compressive bending resistance and <=0.1g/cm<3> apparent density is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretchable nonwoven fabric with excellent stretchability, bulkiness and flexibility, and more particularly to a stretchable nonwoven fabric with excellent stretchability, ie, stretchability and stretch recovery.

0002

BACKGROUND OF THE INVENTION Conventionally, nonwoven fabrics whose constituent fibers are crimped fibers have been used as base fabrics for medical and sanitary materials such as poultices and supporters. This nonwoven fabric has good elasticity due to the elasticity of the crimped fibers that are its constituent fibers, and is preferable as a base fabric for medical hygiene materials applied to the human body. It is also preferable as a surface material for disposable diapers, sanitary napkins, etc.

Various types of nonwoven fabrics have been proposed as such stretchable nonwoven fabrics. For example, Special Publication No. 1-21257
The publication describes a nonwoven fabric that can be suitably used as a base fabric for medical hygiene materials, and is made by heat-treating a fiber web made of latent crimpable composite fibers to cause the latent crimpable composite fibers to develop crimps. Non-woven fabrics have been proposed. However, this nonwoven fabric uses heat-adhesive conjugate fibers together with latent crimp conjugate fibers, and the crimped fibers are fused together over the entire area of the non-woven fabric using the heat-adhesive conjugate fibers. However, the stretchability, that is, the stretchability and stretchability were still insufficient. That is, since the crimped fibers are fixed, they are difficult to stretch, and once the crimped fibers are stretched to such an extent that they are no longer fixed, it is difficult to recover.

[0004] Furthermore, JP-A-2-191757 discloses that a fibrous web made of latent crimpable fibers is heat-treated to form latent crimpable fibers as a nonwoven fabric that can be suitably used as a base fabric for medical hygiene materials. A nonwoven fabric that is crimped has been proposed. This nonwoven fabric also uses heat-adhesive conjugate fibers together with latent crimpable fibers, but unlike the nonwoven fabrics described above, a point fusion area is provided not over the entire area of the nonwoven fabric, but in that area. The compressed fibers are fused together using heat-adhesive conjugate fibers. Therefore, although it has excellent elasticity to some extent, the nonwoven fabric obtained by the method described in JP-A-2-191757 actually has an elongation recovery rate of about 15% when elongated by 30%, and is medically hygienic. It did not have sufficient elasticity as a base fabric for materials. The reason for this is not clear, but due to lack of sufficient consideration in setting the crimp onset temperature and the temperature (emboss temperature) when creating the point welding area, crimped fibers are It is thought that this is because they are fused together by the heat-adhesive conjugate fibers. Therefore, it had the same drawbacks as the stretchable nonwoven fabric described in Japanese Patent Publication No. 1-21257.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a nonwoven fabric that is composed of crimped fibers and heat-adhesive fibers and has a point-fused area, but has no crimping in areas other than the point-fused area. The purpose is to provide a nonwoven fabric with great elasticity by hardly fusion bonding the shrink fibers and the heat-adhesive fibers.

[0006]

[Means for Solving the Problems] That is, the present invention provides a nonwoven fabric having the following structure, in which the elongation recovery rate at 30% elongation is 25% or more in both length and width, and the compression stiffness is 80 g.
It relates to a stretchable nonwoven fabric characterized by having an apparent density of 0.1 g/cm 3 or less. Note (a) The nonwoven fabric contains polypropylene crimped fibers (hereinafter referred to as "A fibers") and thermal adhesive fibers (hereinafter referred to as "B fibers").
It is called "fiber". ), and the weight ratio of both is A fiber: B fiber = 100 (parts by weight): 5 to 400 (
(parts by weight). (b) A fiber is a composite fiber consisting of a first component (hereinafter referred to as "A1 component") and a second component (hereinafter referred to as "A2 component"), and the melting point of the A1 component (hereinafter referred to as "A2 component"). "A1
m”. ) should be lower than the melting point of the A2 component (hereinafter referred to as "A2m"). (c) B fiber is a composite fiber consisting of a first component (hereinafter referred to as "B1 component") and a second component (hereinafter referred to as "B2 component"), and the melting point of the B1 component (hereinafter referred to as "B2 component"). “B1
m”. ) is lower than A1m, and the melting point of the B2 component (hereinafter referred to as "B2m") is higher than B1m. (d) The nonwoven fabric is provided with point-fused areas intermittently, and in the point-fused areas, the A fibers and the B fibers are bonded together by melting and solidifying the B1 component of the B fibers. It must be fused and retain its nonwoven form. (e) In non-fused areas other than the point fused area, the A
The fibers, the B fibers, and the A fibers and the B fibers each do not have a melting point. (f) The crimping of the A fibers is caused by applying heat at the same time or immediately after providing a point fusion zone to the polypropylene latent crimpable fibers.

First, fiber A, which is one of the constituent fibers of the nonwoven fabric according to the present invention, will be explained. A fiber is a polypropylene composite fiber consisting of A1 component and A2 component. And A1m is lower than A2m. In the present invention, the melting point refers to the temperature that gives the extreme value of the melting and absorption curve measured using a differential scanning calorimeter DSC-2 manufactured by PerkinElmer at a heating rate of 20° C./min.

[0008] The A fibers are made by applying heat to polypropylene latent crimpable fibers (hereinafter referred to as "original A fibers") to develop crimps. As this raw A fiber, for example, the following fibers can be used.

[0009] This raw A fiber is a state in which the A fiber has not yet developed crimp, and therefore, like the A fiber, the A fiber
It is a composite fiber consisting of A1 component and A2 component. As a raw material for component A1, a polypropylene polymer obtained by random copolymerization of propylene, ethylene, etc. is generally used. This polypropylene polymer has a lower melting point than a polypropylene polymer obtained by polymerizing propylene alone, and is commonly used as a raw material for component A1. In particular, copolymerization of propylene and ethylene lowers the melting point and increases the thermal shrinkage rate, making it preferable as a raw material for the A1 component. When copolymerizing propylene and ethylene, it is preferable that the weight ratio of the two is as follows. That is, it is preferable to copolymerize propylene at 92 to 97% by weight and ethylene at 3 to 8% by weight. The melting point of such a polypropylene polymer, that is, the melting point of the A1 component (A1m) is 130 to 150°C, preferably 132 to 148°C, most preferably 135 to 145°C.
It is ℃. When the weight ratio of ethylene is less than 3% by weight,
The melting point decreases less, the heat shrinkage rate decreases, and the occurrence of crimp tends to decrease. Furthermore, increasing the weight ratio of ethylene to more than 8% by weight tends to reduce the productivity of the polypropylene polymer. That is, when obtaining such a copolymer, the proportion of by-products soluble in the polymerization solvent (hydrocarbon) increases, which tends to reduce productivity and become industrially uneconomical. The forms of random copolymerization of propylene and ethylene include those in which ethylene is copolymerized at random, and block copolymerization in which a certain number of ethylenes are bonded to each other and inserted between propylene. However, in the present invention, it is preferable to use the former type. If the latter type is used, the structure consisting of ethylene exists in block units in the main chain of polypropylene, resulting in non-uniform heat shrinkage properties, extremely poor spinnability, and difficulty in melt spinning. This is because it becomes difficult to form the fiber into a fiber form.

[0010] As a raw material for component A2, it is common to use a polypropylene polymer obtained by random copolymerization of propylene and ethylene, and in particular, a polypropylene polymer obtained by copolymerizing propylene and ethylene. is preferable, but its melting point (A2m) is determined by changing the melting point (A2m) of the A1 component (
It must be higher than A1m). Therefore, A2
The amount of ethylene in the ingredient feed must be less than the amount of ethylene in the A1 component. That is, it is preferable to copolymerize propylene at 97 to 100% by weight and ethylene at 0 to 3% by weight. The amount of ethylene is 3% by weight
If it exceeds this value, the difference between A2m and A1m and the heat shrinkage rate will decrease, and crimp development when heat is applied to the raw A fibers will tend to decrease.

[0011] The A1 component and the A2 component are combined to form the raw A fiber, and this composite form can be a parallel composite type, an eccentric circular core-sheath composite type, or an irregular cross-section composite type. . In particular, in order to emphasize the difference in heat shrinkage rate between A1 component and A2 component and increase crimp development of A fibers,
A parallel complex type is preferred. Further, in the case of an eccentric circular type core/sheath composite type, it is preferable that the eccentricity defined by the following formula is 15 or more. Eccentricity = [(distance between the center of the single fiber diameter and the center of the core component diameter) x 100]/(single fiber radius). When the eccentricity is less than 15, crimp development tends to decrease.

[0012] The raw A fibers as described above generally have a crimp onset temperature of [(A1m)-40°C] or higher. It is preferable that the crimp onset temperature has a small minimum value and a wide range. This is because it becomes easy to set the temperature at which crimping occurs, and a nonwoven fabric with stable quality can be obtained. If the crimp development temperature is less than [(A1m)-40°C], crimp development may occur during the fiber drying process during production of the raw A fiber. In particular, if such crimping occurs, there is a risk that neps (clumps of unsplit fibers) will occur in the fibrous web when the raw A fibers are made into short fibers and opened with a card to obtain a fibrous web. be. In addition, the temperature at which the raw A fibers actually develop crimp is generally A1m or lower. This is because if crimp development is performed at a temperature exceeding A1m, there is a risk that A fibers or A fibers and B fibers may fuse together even in areas other than the point fusion area of the nonwoven fabric. Therefore, in reality, the temperature adopted as the crimp onset temperature of the raw A fiber is [(A1
m)-35°C] to [(A1m)-5°C] are preferred, and furthermore, [(A1m)-30°C] to [(A1m)-10°C] are most preferred.

[0013] When such raw A fibers are used, the general index of the heat shrinkage rate (dry heat shrinkage rate) is as follows. That is, the dry heat shrinkage rate at a temperature of 100°C is 30% or more, and the dry heat shrinkage rate at a temperature of 120°C is 35%.
That's all. When the dry heat shrinkage rate is smaller than this value, the degree of crimp development is small, and the obtained nonwoven fabric tends to be unable to have sufficient stretchability and bulk. The method for measuring the dry heat shrinkage rate is as follows. That is, single fiber total 1
Five fibers were used as samples, and an initial load of 2 mmg/denier was applied to each single fiber, and the length a (cm) at that time was measured, and then heat treated in an air oven type heat treatment machine at 120 ° C. for 15 minutes. The length b (cm) was measured, the shrinkage rate was calculated using the following formula, and the average value was taken as the dry heat shrinkage rate. Shrinkage rate (%)=[(ab)×100]/a. Further, a general index of the degree of crimp development when heat is applied to the raw A fibers is as follows. That is, 40 pieces/25 mm or more at a temperature of 100°C, and 6 pieces/25 mm at a temperature of 120°C.
0 pieces/25mm or more. If the degree of crimp development is less than this, there will be a tendency that sufficient stretchability cannot be imparted to the resulting nonwoven fabric.

Next, B fiber, which is one of the constituent fibers of the nonwoven fabric according to the present invention, will be explained. B fiber is a composite fiber consisting of B1 component and B2 component. B1m is A1m
It is lower. Further, B2m is higher than B1m. Therefore, this B1 component plays a role in adhering each fiber to each other in the point welding area of the nonwoven fabric according to the present invention. The reason for using a composite fiber as the B fiber is as follows. In other words, if the B fibers are composed only of the B1 component, which is a low melting point component, the B fibers will lose their fiber form in the point fused area, and the B fibers will lose their fiber form at the boundary between the point fused area and the non-fused area. becomes easier to cut,
This is because it adversely affects elongation recovery. Furthermore, the fiber strength of the B fibers may be reduced, and the nonwoven fabric strength may also be reduced. Furthermore, when B fibers are passed through a card as short fibers, it is necessary to bend the B fibers in order to improve card suitability, but this bending tends to be difficult.

[0015] The B fiber may be one in which crimping is caused by applying heat to a latent crimpable fiber, or
It may be a non-latent crimpable fiber that does not develop crimp, but the fiber that is the raw material for obtaining this B fiber may be
Hereinafter referred to as "original B fiber". In order to make the raw B fiber into a latent crimpable fiber, as in the case of the raw A fiber, the B1 component and the B
The two components may be combined as a parallel composite type, an eccentric circular core-sheath composite type, or an irregular cross-section composite type. Furthermore, in order to obtain a non-latently crimpable fiber, the B1 component and the B2 component may be combined using a concentric core-sheath composite type, a point-symmetric split type, or the like. Furthermore, crimp may not occur by not providing a difference in heat shrinkage rate between the B1 component and the B2 component, or by adjusting the melt flow rate of the B1 component. As the raw material for component B1, modified thermoplastic polymers such as polyethylene, copolymerized polypropylene, copolymerized polyethylene terephthalate, copolymerized polybutylene terephthalate, nylon, and ethylene-vinyl alcohol copolymer can be used. Further, as the raw material for component B2, thermoplastic polymers such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, copolymerized nylon, ethylene-vinyl alcohol copolymer, and modified thermoplastic polymers thereof can be used.

The A fibers and B fibers described above are the constituent fibers of the stretchable nonwoven fabric according to the present invention. The weight ratio of A fibers and B fibers in the stretchable nonwoven fabric is A fiber: B fiber = 100 (parts by weight): 5 to 400 (parts by weight). Particularly preferably A fiber: B fiber = 100 (parts by weight): 10 to 300 (parts by weight), most preferably A
Fiber: B fiber = 100 (parts by weight): 15 to 250 (parts by weight). When the weight ratio of B fibers is less than 5 parts by weight, the amount of B1 component, which is a fusion component in the point fusion area, becomes relatively small, resulting in insufficient fusion of A fibers and B fibers, resulting in a nonwoven fabric. This is not preferred because the shape cannot be maintained. Furthermore, if the weight ratio of the B fibers exceeds 400 parts by weight, the amount of the A fibers becomes relatively small and the elasticity of the nonwoven fabric due to crimp decreases, which is not preferable. In addition, other types of fibers may be mixed in the stretchable nonwoven fabric according to the present invention in addition to the A fibers and B fibers. For example, wool, cotton,
Natural fibers such as hemp, cellulose fibers such as acetate and rayon, composite conductive fibers kneaded with carbon black, or other modified thermoplastic fibers may be mixed.

The stretchable nonwoven fabric according to the present invention is provided with point fusion areas intermittently. In this point welding area, the A fiber and the B1 component of the B fiber are melted and solidified.
The fibers are fused together. This point fusion allows the stretchable nonwoven fabric according to the present invention to maintain its shape. This point-fused area is formed by forming a fibrous web consisting of raw A fibers and raw B fibers, and introducing this fibrous web into a known embossing roll. The temperature of the embossing roll is preferably [B1m-15°C] to A1m. The temperature of the embossing roll is [B1m-1
5°C], it is difficult for the B1 component to melt and solidify in the point fusion area, making it difficult to fuse the A fibers and B fibers together, and insufficient strength to maintain the nonwoven fabric form. It becomes a trend. On the other hand, if the temperature of the embossing roll is A1
If it is higher than m, there is a risk that the A1 component of the raw A fibers will melt, and the crimp of the raw A fibers will not be sufficiently developed, and the A fibers will not be crimped even in areas other than the point fusion area. There is a risk of fusion. The total area of the point fusion area is
It is preferable that the amount is 6% or more based on the total area of the nonwoven fabric. As mentioned above, since the point fusion area is formed to maintain the nonwoven fabric form, if it is less than 6%, the nonwoven fabric form tends to be insufficiently maintained. On the other hand, if the total area of the point-fused areas is 50% or more, the non-fused areas will be relatively small, the length of the A fibers that can freely expand and contract will become shorter, and the elasticity will tend to decrease. Become. Furthermore, the number of point-fused areas increases relatively, which tends to deteriorate the feel of the nonwoven fabric. Therefore, the total area of the point fused areas is preferably about 8 to 45%, most preferably about 10 to 40%. Incidentally, the total area of the point fused area of the nonwoven fabric is measured by the following measuring method. In other words, several small pieces of nonwoven fabric were photographed under magnification using a scanning electron microscope, and the ratio of the sum of the areas of the point-welded parts to the area of the smallest repeating unit was measured 10 times individually. The average value of the total area of the point fused area of the nonwoven fabric was measured.

In areas other than this point fused area, ie, non-fused areas, A fibers are bonded to each other, B fibers are bonded to each other, and A fibers and B fibers are bonded to each other.
The fibers do not have their own fusion points. Therefore, in the non-fused area, the crimped A fibers exist without bonding points, and when an external force is applied, they are freely extended, and when the external force is removed, they are freely restored to their original state. For example, the unfused area is like a spiral spring that exists in a free state. Both ends of this spiral spring are fixed at the point welding area. Therefore, the presence of this non-fused area provides good stretchability of the stretchable nonwoven fabric according to the present invention. The crimp of the A fibers in this non-fused area was developed by applying heat to the raw A fibers. This crimp development is performed at the same time as or immediately after providing the point welding area. For example, if this crimp development is performed before providing the point fused areas, good stretchability cannot be imparted to the nonwoven fabric. Although the reason for this is not clear, it is thought that a portion of the crimped portions of the A fibers are bonded together by the point welding area, which inhibits the good elasticity associated with the crimping of the A fibers.

The stretchable nonwoven fabric according to the present invention as described above is
The elongation recovery rate at 30% elongation is 25% or more in both length and width. Here, the elongation recovery rate at 30% elongation is determined by the following measurement method. That is, using Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co., Ltd., a sample piece with a sample width of 2.5 cm and a sample length of 10 cm was stretched at a tensile speed of 10 cm/min according to the strip method described in JIS L-1096A. Tested and elongation was 30%
A strength-elongation curve was drawn at that point (line E in Figure 1), and then the tension was released from the sample piece, and a strength-elongation curve was drawn for the sample piece (line R in Figure 1). The area of the dotted line shown in Figure 1 (
X) and the area (Y) of the shaded area were measured and determined by the following formula. In other words, the elongation recovery rate at 30% elongation (%
)=100Y/(X+Y). Furthermore, the lengthwise direction of the nonwoven fabric refers to the direction in which machines are arranged during the production of the nonwoven fabric, and the widthwise direction of the nonwoven fabric refers to the direction perpendicular to the longitudinal direction. If the elongation recovery rate at 30% elongation is less than 25% in either the vertical or horizontal direction of the nonwoven fabric, the desired elasticity of the present invention cannot be obtained.

[0020] Furthermore, the compression stiffness of the stretchable nonwoven fabric according to the present invention is 80 g or less. The compression resistance represents the flexibility of the nonwoven fabric, and the smaller the compression resistance value, the more flexible the nonwoven fabric is. Here, compression stiffness is measured by the following method. In other words, a sample piece with a sample width of 50 mm in the machine direction of the nonwoven fabric (lengthwise of the nonwoven fabric) and a sample length of 100 mm in the direction orthogonal to this direction is divided into 5 pieces.
After preparing a sample piece, bending each sample piece in the sample length direction to make a cylindrical shape, and joining both ends to create a sample, Tensilon UTM-4-1-10 manufactured by Toyo Baldwin Co., Ltd.
The sample was compressed in the width direction of the sample at a compression rate of 50 mm/min using 0, the stress at the maximum load was measured, and the average value was taken as the compression stiffness. If the compression bending strength of the nonwoven fabric exceeds 80 g, the flexibility of the nonwoven fabric will decrease and a rough and hard feeling will appear, which is not preferable. In the present invention, it is particularly preferable that the compression bending strength is 50 g or less, and most preferably 30 g or less.

[0021] Furthermore, the apparent density of the stretchable nonwoven fabric according to the present invention is 0.1 g/cm3 or less. The apparent density indicates the bulkiness of the nonwoven fabric, and the smaller the value, the more bulky the nonwoven fabric is. Here, the apparent density is measured by the following method. That is, the sample width is 10 cm,
After preparing five sample pieces with a sample length of 10 cm and measuring the area weight (g/m2) for each sample piece, a load of 4.5 g/cm2 was applied to the sample piece using a thickness measuring device manufactured by Daiei Kagaku Seiki Seisakusho. was applied, the thickness (t) after being left for 10 seconds was measured, and the apparent density was calculated using the following formula, and the average value was taken as the apparent density of the nonwoven fabric. Apparent density (g/cm3) = [Basic weight (
g/m2)/1000t(mm)]. If the apparent density exceeds 0.1 g/cm3, the bulkiness aimed at by the present invention cannot be achieved.

[0022]

[Example] First, the following A-1 fibers and A-2 fibers were prepared as raw A fibers. [A-1 fiber] 96% by weight of propylene as A1 component
A polypropylene polymer randomly copolymerized with 4% by weight of ethylene and having a melting point (A1m) of 138°C, a melt flow rate of 10 g/10 minutes, and a Q value of 5.5, As the A2 component, the melting point (
A2m) 162℃, melt flow rate value 30g/10
A polypropylene polymer having a Q value of 6.0 was used in each case and melted in a conventional extruder type extruder. In this example, the method for measuring the melt flow rate value was based on ASTM D1238(L). Thereafter, using a parallel type composite spinneret with a spinning hole diameter of 0.5 mm and a number of holes of 300, the single hole discharge rate was set to 0.5 g/min for each hole, that is, A1
270℃ with the ratio (weight ratio) of component and A2 component to 1/1
Melt spinning was carried out at a spinning temperature of . After melt spinning, the yarn was taken off at a take-off speed of 1000 m/min to obtain an undrawn parallel type composite filament yarn. Several dozen undrawn parallel composite filament yarns were bundled into a tow and then hot stretched. The stretching method used a two-stage hot roller stretching machine at a stretching speed of 100.
m/min, first roller temperature 70℃, second roller temperature 9
The stretching was carried out at 0° C., the third roller temperature was 25° C., and the stretching ratio was 80% of the maximum stretching ratio. This stretched tow is fed to a stuffer box and bent at 12 pieces/25 mm, then a finishing oil is applied and dried at a temperature of 70°C to form parallel composite short fibers with a single fiber fineness of 2 denier and a fiber length of 51 mm. Raw cotton (A-1 fiber) was obtained. This A-1 fiber has a strength of 5.96 g/d and an elongation of 68%,
Further, the dry heat shrinkage rate at a temperature of 100°C was 35%, and the dry heat shrinkage rate at a temperature of 120°C was 53%. In addition,
In this example, the strength and elongation of the fibers was measured using Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co., Ltd., at a tensile rate of 20 mm/min on a sample having a sample length of 20 mm. Furthermore, when the "A-1" fiber was heat-treated at a temperature of 100°C, 62 crimps/25 mm were developed, and when it was heat-treated at a temperature of 120°C, 112 crimps/25 mm were developed.

[A-2 fiber] The A2 component is a polypropylene polymer obtained by random copolymerization of 97.5% by weight of propylene and 2.5% by weight of ethylene, and has a melting point of 1.
49℃, melt flow rate 20g/10min, Q value 5
．． A-2 fibers were obtained in the same manner as in the case of the A-1 fibers, except that the polypropylene polymer No. 7 was used. This A-2 fiber has a dry heat shrinkage rate of 3 at a temperature of 100°C.
9%, and the dry heat shrinkage rate at a temperature of 120°C was 57%. In addition, when heat treated at a temperature of 100℃, 82 pieces/2
A crimp of 5 mm was developed, and when heat treated at a temperature of 120° C., 132 crimp/25 mm were developed.

Next, the following B-1 to B-6 fibers were prepared as raw B fibers. [B-1 fiber] Melting point (B1m) 132 as B1 component
°C, density 0.96g/cm3, melt index 20
The B2 component is polyethylene terephthalate, which has a melting point (B2m) of 258°C and a relative viscosity of 1.38 at 20°C when dissolved in a solvent containing equal amounts of tetrachloroethane and phenol. Each was melted using a conventional extruder type extruder. In addition, in this example, the melt index was measured by the method of ASTM D1238(E). Thereafter, using a core-sheath type composite spinneret with a spinning hole diameter of 0.5 mm and 300 holes, the single hole discharge rate was adjusted to 0.3 g/min, that is, B
280 assuming the ratio (weight ratio) of component 1 and component B2 to 1/1
Melt spinning was carried out at a spinning temperature of °C. In addition, in this melt spinning, the B1 component served as a sheath and the B2 component served as a core. After melt spinning, the yarn was taken off at a take-off speed of 1000 m/min to obtain an undrawn core-sheath type composite filament yarn. Several dozen undrawn core-sheath type composite filament yarns were bundled into a tow and then hot-stretched. The stretching method used a two-stage heated roller stretching machine, with a stretching speed of 100 m/min and a first roller temperature of 6.
5℃, second roller temperature 90℃, third roller temperature 25℃
℃ and a stretching ratio of 3.0. This stretched tow was fed to a stuffer box and bent at 11 bends/25mm, then a finishing oil was applied and dried at a temperature of 70°C.A core-sheath type composite short with a single fiber fineness of 2 denier and a fiber length of 51mm was prepared. Raw cotton of fiber (B-1 fiber) was obtained. 11 pieces of this raw cotton
After heat treatment with a hot air dryer at 0℃ and measuring the number of crimp, it was 9.
There were 8 pieces/25mm.

[B-2 fiber] The B1 component is a polyamide polymer made by copolymerizing nylon 6, nylon 66, and nylon 12, and has a melting point (B1m) of 120°C.
, a polyamide polymer with a relative viscosity of 1.92 at 25°C when dissolved in 96% concentrated sulfuric acid, and as the B2 component, a melting point (B2m) of 225°C and 25°C when dissolved in 96% concentrated sulfuric acid. Nylon 6 with a relative viscosity of 2.60 at
Each was melted using a conventional extruder-type extruder. Then, using a core-sheath type composite spinneret with a spinning hole diameter of 0.5 mm and 96 holes, the single hole discharge rate was 0.33
g/min, that is, the ratio (weight ratio) of B1 component and B2 component to 1/
Melt spinning was carried out at a spinning temperature of 265° C. as Example 1. In addition, in this melt spinning, the B1 component served as a sheath and the B2 component served as a core. After melt spinning, take-off speed 3000
The yarn was drawn at a speed of m/min to obtain a semi-drawn core-sheath type composite filament yarn. Several dozen semi-drawn core-sheath type composite filament yarns were bundled into a tow and fed to a stuffer box to be bent at 15 pieces/25 mm, and then a finishing oil was applied and dried at a temperature of 70°C. , single fiber fineness 2 denier,
Raw cotton of core-sheath type composite short fibers (B-2 fibers) with a fiber length of 51 mm was obtained.

[B-3 fiber] As the B1 component, the melting point (B
1m) 132°C, density 0.96g/cm3, melt index 20 high-density polyethylene is used, and as the B2 component, polypropylene weight of melting point (B2m) 162°C, melt flow rate value 30g/min, Q value 6.0. Each was melted in a conventional extruder type extruder using a coalesce. After that, using a core-sheath type composite spinneret with a spinning hole diameter of 0.5 mm and a number of holes of 300, the single hole output amount was 0.5 g/
Melt spinning was carried out at a spinning temperature of 230° C., that is, the ratio (weight ratio) of B1 component to B2 component was set to 1/1. In addition, in this melt spinning, the B1 component served as a sheath and the B2 component served as a core. After melt spinning, take-up speed 1000m/
The filament yarn was removed for a minute to obtain an undrawn core-sheath type composite filament yarn. Several tens of undrawn core-sheath type composite filament yarns were bundled into a tow, which was then hot-stretched in the same manner as the B-1 fiber, and further finished with a finishing oil and dried at a temperature of 70°C. The obtained B-3 fiber had a single fiber fineness of 2 denier,
It was a core-sheath type composite staple fiber with a fiber length of 51 mm.

[B-4 fiber] Product name: Melty <4080
> (manufactured by Unitika Co., Ltd.) was prepared. This fiber is a core-sheath type composite fiber in which a modified polyester having a melting point (B1m) of 110° C. is used as a sheath component (B1 component), and polyester is used as a core component (B2 component). In addition, the fineness of this fiber is 2 denier and the fiber length is 51
It is mm.

"B-5 fiber" As the B1 component, the melting point (B
1m) Use high-density polyethylene at 132°C, density 0.96g/cm3, melt index 20, and as B2 component, polypropylene with melting point (B2m) 160°C, melt flow rate 10g/10min, Q value 6.5. Each was melted using a conventional extruder-type extruder. After that, using a parallel type composite spinneret with a spinning hole diameter of 0.5 mm and a number of holes of 300, the single hole output amount was 0.42 g/
Melt spinning was carried out at a spinning temperature of 230° C., that is, the ratio (weight ratio) of B1 component to B2 component was set to 1/1. After melt spinning, the yarn was taken off at a take-off speed of 1000 m/min to obtain an undrawn parallel composite filament yarn. Several dozen undrawn parallel composite filament yarns were bundled into a tow and then hot stretched. The stretching method used a two-stage hot roller stretching machine, a stretching speed of 100 m/min, and a first roller temperature of 65°C.
, second roller temperature 90℃, third roller temperature 25℃,
The stretching was carried out at a stretching ratio of 4.0. After feeding this stretched tow to a stuffer box and imparting 11 bends/25 mm, a finishing oil was applied and it was dried at a temperature of 70°C.
Raw cotton of parallel composite short fibers (B-5 fibers) with a single fiber fineness of 2 denier and a fiber length of 51 mm was obtained. This raw cotton is heated to 110℃
When heat treated with a hot air dryer and measured the number of crimp, it was 7.
It was 5 pieces/25mm.

"B-6 fiber" 40 mol% of isophthalic acid is copolymerized as B1 component, melting point (B1m) 110°C
A copolymerized polyester of 20°C when dissolved in a solvent containing equal amounts of tetrachloroethane and phenol.
A copolymerized polyester with a relative viscosity of 1.36 is used as the B2 component, and the relative viscosity at 20°C when dissolved in a solvent with a melting point (B2m) of 258°C and a mixture of equal amounts of tetrachloroethane and phenol is 1. .38 copolymerized polyesters were used, each melted in a conventional extruder type extruder. Thereafter, raw cotton was obtained under the same conditions as for obtaining "B-5 fiber". This raw cotton is heated to 110℃
When heat treated with a hot air dryer and measured the number of crimp, it was 8.
It was 2 pieces/25mm.

[0030] In addition, as other fibers, the following C-1,
Two fibers were prepared. [C-1 fiber] trade name <C-81> (manufactured by Unitika Co., Ltd.) was prepared. This fiber is a parallel composite fiber, and has a melting point (B1m) of 243°C as a first component (B1 component).
A modified polyester is used, and polyester is used as the second component (component B2). Further, the fineness of this fiber is 2 denier and the fiber length is 51 mm.

[C-2 Fiber] Cotton fiber was prepared.

Examples 1 to 6 and Comparative Examples 1 and 2 As shown in Table 1, raw fiber A, raw fiber B, and other fibers were mixed in a predetermined ratio and fed to a flat card machine. The fibers were opened to produce a carded web with a basis weight of 50 g/m2.

[Table 1] This card web was introduced into a clearance calender machine manufactured by Yuri Roll Co., Ltd. The lower roll of the clearance calendar machine was a steel flat roll, and the upper roll was an embossed roll having many convex portions. The convex portions of this embossing roll have a density of 10 pieces/cm2
The total area of the convex portions relative to the total area of the roll was as shown in Table 1. In addition, the conditions for introducing the card web into the clearance calendar machine are the introduction speed of 5 m/
min, linear pressure between rolls 27 kg/cm, roll temperature [B1
m-5°C]. Note that the roll temperature in the case where the raw fiber B was not used was the same as in Example 3. After embossing with a clearance calender, a relaxation heat treatment was performed for 1 minute using a hot air circulation heat treatment machine at the same ambient temperature as the roll temperature to obtain a stretchable nonwoven fabric. Table 2 shows the physical properties of this stretchable nonwoven fabric.

[0033]

[Table 2] As is clear from the results in Table 2, it can be seen that the stretchable nonwoven fabric according to the example has excellent stretch recovery properties, bulkiness, and flexibility. However, the stretchable nonwoven fabric according to Example 6 had a relatively large amount of other fibers and a small amount of B fibers, so the KS strength was low and it was difficult to use it for applications requiring strength. In addition, the nonwoven fabric according to Comparative Example 1 had a relatively small amount of A fibers, so it was inferior in stretchability, bulkiness, and flexibility. In the nonwoven fabric according to Comparative Example 2, since the B fibers, which are heat bondable fibers, were not present, it was not possible to provide point fusion areas in the nonwoven fabric using a clearance calender machine.

Examples 7 to 9 and Comparative Example 3 50% by weight of A-1 fibers as raw A fibers and 5% by weight of B-1 fibers as raw B fibers.
0% by weight was mixed and fed to a carding machine and opened to create a carded web with a basis weight of 50g/m2. This card web was introduced into a clearance calendar machine manufactured by Yuri Roll Co., Ltd. The lower roll of the clearance calendar machine was a steel flat roll, and the upper roll was an embossing roll or flat roll shown in Table 3. The conditions for introducing the carded web into the clearance calender machine were an introduction speed of 5 m/min, a linear pressure between the rolls of 27 kg/cm, and a roll temperature of 125°C. Table 3 shows the physical properties of the stretchable nonwoven fabric obtained as a result.

[Table 3] As is clear from Table 3, the stretchable nonwoven fabric according to the example is excellent in stretch recovery, bulkiness, and flexibility. On the other hand, the nonwoven fabric according to Comparative Example 3 was inferior in stretchability, bulkiness, and flexibility because no point fusion area was provided and the entire surface of the nonwoven fabric was thermocompression bonded.

Comparative Example 4 A blend of 50% by weight of A-1 fibers as raw A fibers and 50% by weight of B-3 fibers as raw B fibers was fed twice to a flat card machine and opened, and the basis weight was A parallel web of 20 g/m2 was created. This parallel web was introduced into a hot air circulation dryer set at an ambient temperature of 140°C,
Thereafter, it was introduced between an embossed metal roll and a flat rubber roll at room temperature at the outlet of a dryer to obtain a nonwoven fabric shaped into an embossed mold. Table 4 shows the physical properties of the obtained nonwoven fabric.

[Table 4] As is clear from Table 4, this nonwoven fabric has A fibers mutually, B fibers mutually, and A fibers mutually in areas other than the patterned areas.
The fibers and the B fibers were bonded to each other, and the elasticity and flexibility were poor. This is considered to be because the parallel web was introduced into the hot air circulation dryer, which was set at a temperature higher than A1m. Furthermore, this nonwoven fabric had unevenness in area due to shrinkage of each fiber, and was extremely poor in texture and quality. Therefore, this nonwoven fabric is unsuitable as a surface material for medical hygiene materials such as disposable diapers and sanitary napkins.

Examples 10 to 13 and Comparative Example 5 70% by weight of A-1 fibers as raw A fibers and 30% by weight of B-2 fibers as raw B fibers were mixed and fed to a carding machine and opened. A card web with a basis weight of 50 g/m2 was prepared. This card web was introduced into a clearance calendar machine manufactured by Yuri Roll Co., Ltd. The temperature of the embossing roll (processing temperature) was changed as shown in Table 5, and the other processing conditions were the same as in Example 1. Table 5 shows the physical properties of the nonwoven fabric obtained as a result.

[Table 5] As is clear from Table 5, the nonwoven fabrics according to Examples are excellent in stretch recovery properties, bulkiness, and flexibility. However, since the stretchable nonwoven fabric according to Example 13 had a low processing temperature, its KS strength was low and it was difficult to use it for applications requiring strength. In addition, in the nonwoven fabric according to Comparative Example 5, the processing temperature was too high during the manufacturing process, and each fiber partially melted or softened even in areas other than the point fusion area, resulting in a flat nonwoven fabric immediately after embossing. It got wrapped around the roll and could not be realistically produced.

Examples 14 to 19 and Comparative Example 7 Stretchable nonwoven fabrics were obtained using the fiber blends shown in Table 6 under the same conditions as Examples 1 to 6. Therefore, the embossing roll temperature is [B1
m-5°C].

Table 6 Table 7 shows the physical properties of the stretchable nonwoven fabric obtained.

[Table 7] As is clear from the results in Table 7, it can be seen that the stretchable nonwoven fabric according to the example has excellent stretch recovery properties, bulkiness, and flexibility. However, the stretchable nonwoven fabric according to Example 19 had a relatively large amount of other fibers and a small amount of B fibers, so the KS strength was low and it was difficult to use it for applications requiring strength. In addition, the nonwoven fabric according to Comparative Example 7 had a relatively small amount of A fibers, so it was inferior in stretchability, bulkiness, and flexibility.

Examples 20 to 22 and Comparative Example 8 Examples 7 to 9 except that B-5 fiber was used instead of B-1 fiber.
A stretchable nonwoven fabric was obtained in the same manner as in Comparative Example 3. The results are shown in Table 8.

[Table 8] As is clear from Table 8, the stretchable nonwoven fabric according to the example is excellent in stretch recovery, bulkiness, and flexibility. On the other hand, the nonwoven fabric according to Comparative Example 8 was inferior in stretchability, bulkiness, and flexibility because no point fusion area was provided and the entire surface of the nonwoven fabric was thermocompression bonded.

Comparative Examples 9 to 12 As shown in Table 9, raw fiber A, raw fiber B, and other fibers were mixed in a predetermined ratio, fed to a flat card machine, opened, and fabricated. A card web of 80 g/m2 was produced.

[Table 9] This card web was introduced into a hot air circulation dryer set at an ambient temperature of 130°C and heat-treated for 1 minute to develop crimp in both raw fibers A and B, and the basis weight was 100 g.
/m2 of the crimped fiber web. Next, with a spot embossing machine, the point fusion density is 1 piece/cm2, and the spot fusion area is 1 m2.
A nonwoven fabric was obtained by subjecting it to point fusion at a rate of m2/piece. Table 10 shows the physical properties of this nonwoven fabric.

[Table 10] As can be seen from Table 10, the nonwoven fabrics according to each comparative example were
Since point fusion occurred after crimping occurred, the crimped portion of the crimped fiber was fixed and had poor elasticity. In addition, after crimping occurs and the apparent density increases, point fusion occurs, so
This nonwoven fabric had a large apparent density and poor flexibility. Moreover, this nonwoven fabric has visible spots due to crimping of the raw A fibers and raw B fibers, and is extremely inferior in both texture and quality, and is not suitable for use as a surface material for medical hygiene materials such as disposable diapers and sanitary napkins. was inappropriate.

Example 23 and Comparative Examples 13 and 14 50% by weight of A-2 fibers as raw A fibers and B-2 fibers as raw B fibers
A carded web having a basis weight of 50 g/m2 was prepared by mixing 50% by weight of fibers and supplying the mixture to a carding machine and opening it. This card web was introduced into a clearance calendar machine manufactured by Yuri Roll Co., Ltd. The temperature of the embossing roll (processing temperature) was changed as shown in Table 11, and the other processing conditions were the same as in Example 1. Table 11 shows the physical properties of the nonwoven fabric obtained as a result.

[Table 11] As is clear from Table 11, the nonwoven fabrics according to Examples are excellent in stretch recovery, bulkiness, and flexibility. On the other hand, the nonwoven fabric according to Comparative Example 13 was unable to form a point fusion part due to the low processing temperature, and broke due to slight elongation.
It was not possible to measure the elongation recovery rate. In addition, in the nonwoven fabric according to Comparative Example 14, the processing temperature was too high during the manufacturing process, and each fiber partially melted or softened even in areas other than the point fusion area, resulting in a flat nonwoven fabric immediately after embossing. It got wrapped around the roll and could not be realistically produced.

[0041]

Effects of the Invention As explained above, the stretchable nonwoven fabric according to the present invention is made by mixing specific amounts of specific A fibers and specific B fibers, and the A fibers and B fibers are in a specific form. Since it is adhesive and the physical properties of this nonwoven fabric are within a certain range, it has excellent elasticity, flexibility, and bulkiness, and can be used as a base fabric for medical sanitary materials such as poultices and supports, or for disposable diapers and menstrual hygiene products. It can be suitably used as a surface material for sanitary products such as sanitary napkins.

[Brief explanation of the drawing]

FIG. 1 is a strength-elongation curve for explaining the definition of elongation recovery rate used in the present invention.

Claims (4)

[Claims] Claims: 1. A nonwoven fabric having the following structure, which has an elongation recovery rate of 25% or more in both length and width at 30% elongation, a compression stiffness of 80g or less, and an apparent density of 0.
A stretchable nonwoven fabric characterized by having a weight of 1 g/cm3 or less. Note (a) The nonwoven fabric contains polypropylene crimped fibers (hereinafter referred to as "A fibers") and thermal adhesive fibers (hereinafter referred to as "B fibers").
It is called "fiber". ), and the weight ratio of both is A fiber: B fiber = 100 (parts by weight): 5 to 400 (
(parts by weight). (b) A fiber is a composite fiber consisting of a first component (hereinafter referred to as "A1 component") and a second component (hereinafter referred to as "A2 component"), and the melting point of the A1 component (hereinafter referred to as "A2 component"). "A1
m”. ) should be lower than the melting point of the A2 component (hereinafter referred to as "A2m"). (c) B fiber is a composite fiber consisting of a first component (hereinafter referred to as "B1 component") and a second component (hereinafter referred to as "B2 component"), and the melting point of the B1 component (hereinafter referred to as "B2 component"). “B1
m”. ) is lower than A1m, and the melting point of the B2 component (hereinafter referred to as "B2m") is higher than B1m. (d) The nonwoven fabric is provided with point-fused areas intermittently, and in the point-fused areas, the A fibers and the B fibers are bonded together by melting and solidifying the B1 component of the B fibers. It must be fused and retain its nonwoven form. (e) In non-fused areas other than the point fused area, the A
The fibers, the B fibers, and the A fibers and the B fibers each do not have a melting point. (f) The crimping of the A fibers is caused by applying heat at the same time or immediately after providing a point fusion zone to the polypropylene latent crimpable fibers. 2. The stretchable nonwoven fabric according to claim 1, wherein the B fibers are crimped fibers, and the crimp of the B fibers is developed by applying heat to latent crimpable fibers. 3. The stretchable nonwoven fabric according to claim 1, wherein the B fibers are non-crimped fibers. 4. The stretchable nonwoven fabric according to claim 1, wherein the total area of the point-fused areas is 6% or more of the total area of the nonwoven fabric.