JP2009022747A - Sanitary commodity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-woven fabric which is used for various materials in a sanitary commodity, feels pleasant in texture, and can be disposed with little influence brought on environment. <P>SOLUTION: The sanitary commodity uses a non-woven fabric constituted of a composite long fiber, wherein the composite long fiber is composed of a polylactic acid base polymer and a polyolefin base polymer having a lower melting point than the polylactic acid base polymer; and the polyolefin base polymer forms at least a part of the surface of the composite long fiber. The composite long fiber is preferably a center-sheath type fiber in which the center is formed by the polylactic acid base polymer and the sheath is formed by the polyolefin base polymer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to sanitary products such as disposable diapers and sanitary products, and more particularly to nonwoven fabrics used for various members constituting sanitary products.

  Conventionally, various nonwoven fabrics have been used as members of sanitary products such as disposable diapers and sanitary products. Among these, the long-fiber nonwoven fabric obtained by the spunbond method is recognized as an important material because it has sufficient strength to withstand practical use even with a relatively low basis weight, and also has flexibility. Yes. Currently, a long fiber nonwoven fabric mainly made of polypropylene is often used as a member such as a top sheet of sanitary goods. By the way, with recent serious environmental problems, mass disposal of disposable sanitary goods has become a problem.

In consideration of mass disposal of sanitary products and environmental problems, the present applicant has proposed to use a nonwoven fabric using a polylactic acid polymer, which is a material biodegraded in nature, as a sanitary product member ( Patent Document 1). According to Patent Document 1, it is possible to maintain flexibility as a polylactic acid-based long fiber nonwoven fabric by reducing the single yarn fineness of the fibers constituting the nonwoven fabric and reducing the basis weight. However, for example, since a top sheet of a diaper is a member that directly touches the skin, better touchability is required. However, in the polylactic acid-based long-fiber nonwoven fabric described in Patent Document 1, the polylactic acid polymer itself is Because of the hardness that is caused, it is difficult to wipe off the crispness.
Japanese Patent Laid-Open No. 2002-242068

  An object of the present invention is to provide a nonwoven fabric that is a nonwoven fabric used for various members of sanitary goods, has good touch properties, and has little influence on the environment upon disposal.

  As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention is a sanitary article in which a nonwoven fabric comprising composite long fibers is used as a sanitary member, and the composite long fibers have a polylactic acid polymer and a melting point lower than that of the polylactic acid polymer. The gist of the present invention is a sanitary product characterized in that it is a composite of a polyolefin polymer, and the polyolefin polymer forms at least a part of the surface of the composite long fiber.

  Hereinafter, the present invention will be described in detail.

  In the sanitary article of the present invention, a nonwoven fabric having composite long fibers as constituent fibers is used as a member. The composite long fiber is a composite of a polylactic acid polymer and a polyolefin polymer having a melting point lower than that of the polylactic acid polymer.

  The polylactic acid-based polymer used in the present invention includes poly-D-lactic acid, poly-L-lactic acid, a copolymer of D-lactic acid and L-lactic acid, and D-lactic acid and hydroxycarboxylic acid. Polymers selected from the group consisting of copolymers, copolymers of L-lactic acid and hydroxycarboxylic acid, and copolymers of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, or blends thereof, etc. Is mentioned. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, and the like. Among these, hydroxycaproic acid and glycolic acid are particularly preferable from the viewpoint of decomposition performance and low cost.

  In the present invention, it is preferable to use a polylactic acid polymer having a melting point of 150 ° C. or higher or a blend thereof. Since the polylactic acid polymer having a melting point of 150 ° C. or higher has high crystallinity, shrinkage hardly occurs during heat treatment such as when heat-bonding the constituent fibers or heat sealing the nonwoven fabric, Moreover, it is because heat processing can be performed stably. Furthermore, since the non-woven fabric is excellent in heat resistance, the non-woven fabric performance and form hardly change during transportation and storage.

  The melting point of poly-L-lactic acid and poly-D-lactic acid, which are homopolymers of polylactic acid, is about 180 ° C. When a copolymer is used as the polylactic acid polymer instead of a homopolymer, the copolymerization ratio of the monomer components is preferably determined so that the melting point of the copolymer is 150 ° C. or higher. For example, in the case of a copolymer of L-lactic acid and D-lactic acid, the copolymerization ratio of L-lactic acid and D-lactic acid is (L-lactic acid) / (D-lactic acid) = 5/95 in molar ratio. ˜0 / 100 or (L-lactic acid) / (D-lactic acid) = 95/5 to 100/0 has a melting point of 150 ° C. or higher. When the copolymerization ratio is out of the above range, the melting point of the copolymer becomes less than 150 ° C. and the amorphous property becomes high.

  As the olefin polymer used in the present invention, polyethylene or polypropylene can be suitably used. Further, polyolefin polymerized using either Ziegler-Natta catalyst or metallocene catalyst can be used. Polyolefin polymerized using a metallocene catalyst is easy to control the molecular weight of the polymer and can sharpen the molecular weight distribution, so when heat-bonding the constituent fibers or heat-sealing the nonwoven fabric In the heat treatment such as, it is preferable because the heat treatment temperature can be easily determined.

  In addition, as the polyolefin-based polymer used in the present invention, biomass-derived polyethylene and polypropylene obtained by using ethanol such as sucrose, starch, cellulose and the like by fermentation technology can be suitably used. This is a method of producing ethylene and propylene by a chemical reaction using a catalyst using ethanol obtained from biomass as a raw material. The obtained biomass-derived ethylene and propylene are made into polyolefins such as polyethylene and polypropylene by a known polymerization technique. As a method for producing polypropylene, in addition to the above-described method for producing from ethanol, propanol is obtained by fermentation using biomass as a raw material, and propylene is produced by a chemical reaction using a catalyst. A method of obtaining polypropylene by a technique may be used. Whether the polymer is made from biomass can be identified by measuring whether or not it contains radioactive carbon. The biomass material contains a very small amount of carbon 14 but does not contain it in a polymer made from petroleum. As a measuring method, a carbon 14 concentration measuring method by accelerator mass spectrometry (Method B) described in ASTM-D-6866 may be used.

  If a polyolefin-based polymer used in the present invention is a biomass-based material, the polylactic acid-based polymer is also a biomass-based material. It can be said that it is a material with consideration.

  In a composite long fiber, a polyolefin polymer having a melting point lower than that of a polylactic acid polymer is combined with a polyolefin polymer having a melting point lower than that of the polylactic acid polymer, so that it functions as a thermal adhesive component. This is because it can. It is more preferable that the difference between the melting points of both is 5 ° C. or more. This is because the polylactic acid polymer is hardly affected by heat during heat treatment. In the present invention, for a polymer having no melting point, the softening point is regarded as the melting point.

  In the composite long fiber, the polyolefin-based polymer forms at least a part of the surface of the composite long fiber. As a composite form (fiber cross-sectional form) in which the polyolefin polymer forms at least a part of the surface of the composite long fiber, for example, a side-by-side type in which a polylactic acid polymer and a polyolefin polymer are bonded together A core-sheath type in which a polylactic acid-based polymer forms a core and a polyolefin-based polymer forms a sheath, a split-type in which a polylactic acid-based polymer and a polyolefin-based polymer are alternately present on the fiber surface, Multileaf type etc. are mentioned. Considering that the polyolefin polymer plays a role as a heat bonding component, it is preferable that the polyolefin polymer is a core-sheath type in which the entire surface of the fiber is formed.

  The composite ratio (mass ratio) of the polylactic acid polymer and the polyolefin polymer is preferably polylactic acid polymer / polyolefin polymer = 4/1 to 1/4. By setting the ratio of the core part to 4/1 or less, the polyolefin-based polymer can sufficiently function as a thermal adhesive, and the nonwoven fabric can exhibit good shape retention and flexibility. Moreover, the nonwoven fabric can fully hold | maintain mechanical strength by making the ratio of a core part 1/4 or more.

  Since the nonwoven fabric in the present invention is preferably a spunbond nonwoven fabric obtained by a spunbond method from the viewpoint of productivity and the like, a viscosity suitable for high-speed spinning is selected for the polymer to be used. The viscosity of the polylactic acid-based polymer was measured in accordance with the method described in ASTM-D-1238 at a temperature of 210 ° C. and a load of 20.2 N (2160 gf) (hereinafter abbreviated as “MFR1”). Is preferably 10 to 80 g / 10 minutes, and more preferably 20 to 70 g / 10 minutes. If the MFR1 is 10 g / 10 min or more, the viscosity will not be too high, so that it is possible to produce without producing a large burden on the screw during melting in the production process. Further, when the MFR1 is 80 g / 10 min or less, the viscosity does not become too small, so that yarn breakage hardly occurs in the spinning process, and the operability is improved.

  Polyethylene has a melt index (hereinafter abbreviated as “MI”) measured at a temperature of 190 ° C. and a load of 20.2 N (2160 gf) in accordance with the method described in ASTM-D-1238 at 5 to 90 g / 10. Polyethylene having a range of minutes is preferably used. By using polyethylene having an MI of 5 g / 10 min or more, melt spinning can be carried out at high speed without extremely increasing the melting temperature during melt spinning. When melt spinning is carried out at an extremely high melting temperature, thermal decomposition of the raw material polymer is promoted, dirt is likely to adhere to the spinneret surface, and operability is significantly impaired. On the other hand, a fiber having high strength can be obtained by using polyethylene having MI of 90 g / 10 min or less. For these reasons, it is more preferable to use polyethylene of 20 to 80 g / 10 minutes.

  Polypropylene has a melt flow rate (hereinafter abbreviated as “MFR2”) measured at a temperature of 230 ° C. and a load of 20.2 N (2160 gf) in accordance with the method described in ASTM-D-1238. Ten minutes of polypropylene is preferably used. By using a polypropylene having an MFR2 of 5 g / 10 min or more, it is melted at a high speed even when the melt temperature is not extremely high, as in the case of the above-mentioned polyethylene having an MI of 5 g / 10 min or more. Spinning can be performed. On the other hand, by setting MFR2 to 80 g / 10 min or more, a high-strength fiber can be obtained as in the case of the above-mentioned polyethylene having an MI of 90 g / 10 min or less. For these reasons, it is more preferable to use polypropylene having an MFR2 of 20 to 80 g / 10 min.

  The single yarn fineness of the composite continuous fiber is preferably 5 dtex or less. By setting the single yarn fineness to 5 dtex or less, it is difficult to feel the hardness when it comes into contact with the skin, and it is difficult to remember the discomfort when wearing sanitary goods. For such a reason, it is more preferable that it is 3 dtex or less. Further, the lower the single yarn fineness, the better the touch, so the lower limit is not particularly limited, but about 1 dtex is preferable from the viewpoint of the production method (spun bond method) in which direct spinning is performed.

  The nonwoven fabric used for the sanitary article of the present invention is composed of the above-mentioned composite fiber, but it is preferable that the constituent fibers are integrated by thermal bonding, and it is particularly preferable that they are thermally bonded by hot embossing. . Heat-embossed nonwoven fabric is given heat and pressure at the embossing point (concaves formed in the nonwoven fabric), but the non-thermal embossing point is almost unaffected by heat and pressure, so it feels good to the touch This is because it becomes a non-woven fabric. Moreover, it is because mechanical characteristics are also favorable and it is excellent in form stability.

The basis weight of the nonwoven fabric in the present invention is not particularly limited since it may be appropriately selected according to the site used in the sanitary product, but generally a range of 15 to 30 g / m ² is preferable. When the basis weight is less than 15 g / m ² , since the number of fibers present per unit area is relatively small, a hole is formed. For example, when used for a top sheet of sanitary goods, There is a risk of uncomfortable feelings due to easy rewetting. On the other hand, when the basis weight exceeds 30 g / m ² , the number of fibers present per unit area is relatively large, and thus the flexibility and water permeability tend to be inferior, and the parts used for hygiene products tend to be limited. It becomes.

  The nonwoven fabric in the present invention preferably has a flexibility of 15 cN or more and 60 cN or less measured according to the handle ohmmeter method described in JIS L 1906. When the degree of flexibility exceeds 60 cN, the texture of the nonwoven fabric becomes hard, and the locations used for sanitary goods tend to be limited.

  The nonwoven fabric in the present invention is composed of long fibers formed by combining the above-described polylactic acid polymer and polyolefin polymer in a specific form, and the reason is not clear, but the flexibility and the touch It has excellent properties and texture, and is thermally stable. Therefore, when used for sanitary goods, heat shrinkage hardly occurs during heat treatment such as bonding with other members by heat sealing or heat sealing, and heat treatment processability is excellent. That is, the nonwoven fabric in the present invention has a thermal contraction rate of 2% or less in the vertical direction when left in an atmosphere of (Tm-10) ° C. for 5 minutes, where the melting point of the polyolefin polymer is Tm.

  The sanitary article of the present invention uses a non-woven fabric comprising a composite long fiber in which a polylactic acid polymer and a polyolefin polymer having a melting point lower than that of the polylactic acid polymer are combined. . Since the polyolefin-based polymer forms at least a part of the surface of the composite long fiber, the yarn-forming property and the fiber-opening property are good, so that it can be produced favorably by the spunbond method. Moreover, since it is a composite form mentioned above, a nonwoven fabric is excellent in a softness | flexibility, the touch property, and a texture. Moreover, when it is used as a sanitary product, heat shrinkage hardly occurs in heat treatment processing such as pasting by heat sealing between the nonwoven fabric and other members or heat sealing processing. In addition, the sanitary article of the present invention is a composite of a polylactic acid polymer and a polyolefin polymer, so that it is incinerated when it has been used, compared to the olefin materials that have been used in the past. The combustion calorie at the time of processing by becomes small, and it can be made small to an environmental load.

  Next, based on an Example, this invention is demonstrated concretely. However, the present invention is not limited to only these examples. In addition, the measurement of the various physical-property values in a following example and a comparative example was implemented with the following method.

(1) Melting point (° C.): Using a differential scanning calorimeter (Perkin Elma, DSC-2 type), the sample mass was 5 mg, the heating rate was 10 ° C./min, and the obtained melting The temperature giving the maximum value of the endothermic curve was defined as the melting point (° C.).

(2) Fineness (decitex): The fiber diameter of 50 fibers in the web state was measured with an optical microscope, and the average value obtained by density correction was defined as the fineness.

(3) Tensile strength (N / 5 cm width) and elongation at break (%): Ten sample pieces each having a sample length of 20 cm and a sample width of 5 cm were prepared. Tensilon UTM-4-1-100, manufactured by Tenshiron, stretched at a grip interval of 10 cm and a tensile speed of 20 cm / min, and the average value of the obtained breaking load at break (N / 5 cm width) was determined as the tensile strength (N / 5 cm). Width). Moreover, the average value of the elongation (%) at the time of cutting was defined as the elongation at break.

(4) Flexibility (cN): Measured according to the handle ohm method described in JIS L 1906.

(5) Texture: The sensory evaluation was carried out in the following three stages with respect to the texture when the nonwoven fabric was touched by hand.
◎: Soft and soft to the touch △: Normal ×: Hard

(6) Thermal contraction rate (%): A sample of 20 cm (longitudinal direction) × 20 cm (lateral direction) is prepared, and the melting point of the low melting point polymer in the fibers constituting the sample is Tm (Tm−10) ° C. After leaving the sample in the atmosphere for 5 minutes, the length L (cm) of each side in the vertical and horizontal directions (4 sides) was measured, and the thermal contraction rate was calculated by the following formula. And those having a heat shrinkage rate of 2% or less on all four sides were evaluated as having low heat shrinkability and good dimensional stability. In addition, the thermal contraction rate of Table 1 described the average value of 4 sides.
Thermal contraction rate = {(20−L) / 20} × 100

Example 1
As a core component, polylactic acid (hereinafter abbreviated as PLA1) having a melting point of 168 ° C., an MFR1 of 20 g / 10 min, and an L-lactic acid / D-lactic acid copolymerization ratio of 98.4 / 1.6 was prepared. As the sheath component, high-density polyethylene (hereinafter abbreviated as HDPE) polymerized using a Ziegler-Natta catalyst with a melting point of 130 ° C., MI of 25 g / 10 min, and a density of 0.95 g / m ³ was prepared.

  The polymer is individually weighed so that the composite ratio (mass ratio) of (PLA1) / (HDPE) is 55/45, and then melted at a temperature of 230 ° C. using an individual extruder-type melt extruder, Using a spinneret having a core-sheath composite cross section, melt spinning was performed at a single-hole discharge rate of 1.3 g / min. After cooling this spun yarn using a known cooling device, using an air soccer installed below the base, the traction speed is reduced to 4300 m / min, and the fiber is opened using a known fiber opening device. did. Next, the filaments were spread and deposited as core-sheath composite long fibers having a single yarn fineness of 3.0 dtex on a screen conveyor that moved the opened yarns to obtain long fiber webs.

Next, the web was passed through a hot embossing device composed of an embossing roll and a smooth metal roll to give a heat treatment to obtain a nonwoven fabric as a sanitary article member having a basis weight of 20 g / m ² . As heat embossing conditions, the surface temperature of both rolls is 120 ° C., and the embossing roll is a circular sculpture pattern with an individual area of 0.6 mm ² , the pressure contact density is 20 / cm ² , and the pressure contact area ratio is 15 % Was used.

Example 2
In Example 1, the nonwoven fabric used as the member of sanitary goods was obtained like Example 1 except having the composite ratio (mass ratio) of (PLA1) / (HDPE) of the core-sheath ratio set to 70/30.

Example 3
In Example 1, as the sheath component, polypropylene having an MFR2 of 35 g / 10 min, a melting point of 160 ° C., and a density of 0.91 g / m ³ was used, and the surface temperature of both rolls was set to 135 ° C. as a heat embossing condition. Obtained the nonwoven fabric used as the member of sanitary goods like Example 1.

Examples 4 and 5
In Example 1, the nonwoven fabric used as the member of sanitary goods was obtained like Example 1 except having a basis weight of 30 g / m ² (Example 4) and a basis weight of 15 g / m ² (Example 5). It was.

Comparative Example 1
A polylactic acid (hereinafter abbreviated as PLA2) having a melting point of 168 ° C., an MFR1 of 65 g / 10 min, and an L-lactic acid / D lactic acid copolymerization ratio of 98.4 / 1.6 was prepared. This polylactic acid was melted at a temperature of 210 ° C. using an extruder-type melt extruder, and melt-spun using a spinneret having a circular cross section at a single-hole discharge rate of 1.7 g / min. After cooling this spun yarn using a known cooling device, using an air soccer installed under the base, the tow speed is reduced to 5000 m / min, and the fiber is opened using a known opening device. did. Next, the filaments were spread and deposited as long fibers having a single yarn fineness of 3.3 dtex on a screen conveyor that moved the opened yarns to obtain a long fiber web.

Next, the web was passed through a hot embossing device composed of an embossing roll and a smooth metal roll to give a heat treatment to obtain a nonwoven fabric as a sanitary article member having a basis weight of 20 g / m ² . The hot embossing conditions were the same as in Example 1 except that the surface temperature of both rolls was 130 ° C.

Comparative Example 2
As a core component, polylactic acid (PLA1) having a melting point of 168 ° C., an MFR1 of 20 g / 10 min, and an L-lactic acid / D-lactic acid copolymerization ratio of 98.4 / 1.6 was prepared. Further, as the sheath component, polylactic acid (hereinafter abbreviated as PLA3) having a melting point of 150 ° C., an MFR1 of 56 g / 10 min, and a copolymerization ratio of L-lactic acid / D lactic acid of 95/5 was prepared.

  The polymer is individually weighed so that the composite ratio (mass ratio) of (PLA1) / (PLA3) is 50/50, and then melted at a temperature of 230 ° C. using an individual extruder-type melt extruder, Using a spinneret having a core-sheath composite cross section, melt spinning was performed at a single-hole discharge rate of 1.5 g / min. After cooling this spun yarn using a known cooling device, using an air soccer installed under the base, the tow speed is reduced to 5000 m / min, and the fiber is opened using a known opening device. did. Next, the filaments were spread and deposited as core-sheath composite long fibers having a single yarn fineness of 3.0 dtex on a screen conveyor that moved the opened yarns to obtain long fiber webs.

Next, the web was passed through a hot embossing device composed of an embossing roll and a smooth metal roll to give a heat treatment to obtain a nonwoven fabric having a basis weight of 20 g / m ² . The hot embossing conditions were the same as in Example 1 except that the surface temperature of both rolls was 110 ° C.

  The evaluation results of the nonwoven fabrics of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1. In addition, about the nonwoven fabric of the comparative example 1, it evaluated in 150 degreeC atmosphere in the case of evaluation of a thermal contraction rate.

The nonwoven fabric used for the sanitary goods member obtained in Examples 1 to 5 had a small flexibility value and excellent flexibility, and also had good touch. The thermal contraction rate was also small, and it had thermal dimensional stability, and was suitable as a sanitary article member.

  On the other hand, Comparative Examples 1 and 2 are non-woven fabrics composed of fibers composed only of a polylactic acid polymer, and the value of the touch property is larger than that of the present invention, and in the touch property, the hardness is It was something that was felt. Further, the heat shrinkage rate was larger than that of the present invention.

Claims (6)

  A non-woven fabric comprising a composite long fiber as a sanitary article is used as a sanitary member, and the composite long fiber includes a polylactic acid polymer and a polyolefin polymer having a lower melting point than the polylactic acid polymer. A sanitary product comprising a composite, wherein the polyolefin polymer forms at least a part of the surface of the composite long fiber.   The sanitary article according to claim 1, wherein the composite long fiber is a core-sheath type composite long fiber in which a polylactic acid-based polymer forms a core and a polyolefin-based polymer forms a sheath. Basis weight of the nonwoven fabric is that a 15 to 30 g / ^{m 2,} sanitary wares according to claim 1 or 2, wherein the flexibility of the nonwoven fabric is less than 60cN least 15 cN.   The sanitary article according to any one of claims 1 to 3, wherein the nonwoven fabric is a composite long fiber constituting the nonwoven fabric integrated by thermal bonding.   The sanitary article according to claim 4, wherein the heat bonding is hot embossing.   The nonwoven fabric has a thermal shrinkage rate of 2% or less when left standing in an atmosphere of (Tm-10) ° C for 5 minutes, where the melting point of the olefin polymer is Tm. The hygiene product according to any one of the above.