Conjugate nonwoven fabric

Abstract

To provide a conjugate nonwoven fabric that uses polylactic acid (PLA) as biodegradable biomass material and has low environmental load and good use feeling when wiping and getting wet with water, and sufficient oil-absorbing speed.SOLUTION: A conjugate nonwoven fabric is formed by laminating a spunbonded nonwoven fabric including polylactic acid (PLA) and a pulp fiber web, and integrating them by a water jet entanglement. Content ratio of the polylactic acid (PLA) in the spunbonded nonwoven fabric is 10% or more. A basis weight of the conjugate nonwoven fabric is 40.0 g / m2 or more and less than 160.0 g / m2. An elongation rate at break in a horizontal direction is less than 75%. An oil-absorbing speed of a pulp fiber web lamination surface is less than 95.0 seconds.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composite nonwoven fabric obtained by hydroentangling a pulp fiber web and a spunbond nonwoven fabric. [Background technology]

[0002] Paper towels, towel sheets, wipers, cloths, etc. are often used to clean oil stains around the kitchen, wipe with water, drain food, and wipe away dirt and dust from the surfaces of precision machinery such as cars and computers.

[0003] The materials used for these sheets and wipers may vary depending on the application, but are often paper made from pulp fibers or nonwoven fabric made from synthetic fibers.

[0004] In recent years, sheets and wipers made of so-called composite nonwoven fabrics, in which pulp fibers and synthetic fibers are laminated or mixed, have also become well known.

[0005] One method for producing such composite nonwoven fabrics is to hydroentangle a spunbond nonwoven fabric made from pulp fibers, which have excellent absorbency for aqueous and oily liquids, and synthetic fibers, which have excellent strength, to produce a sheet that combines strength and absorbency. In this case, the pulp fiber web can be supplied by a general wet papermaking method or dry airlaid, or can also be supplied as a sheet made by wet papermaking.

[0006] Furthermore, polypropylene resin fibers are widely used as a raw material for spunbond nonwoven fabrics, but in recent years, there has been an increasing demand for nonwoven fabrics made from biomass raw materials that are biodegradable, in view of environmental impact.

[0007] For example, Patent Document 1 discloses a nonwoven fabric for wipers, which has a first surface and a second surface opposite the first surface, and contains water-repellent cellulose fibers in a proportion of 10% to less than 75% by mass, based on the total mass of the nonwoven fabric, and other fibers in a proportion of more than 25% to 90% by mass, and at least one of the first surface and the second surface is a surface of a fibrous layer A containing water-repellent cellulose fibers in a proportion of 10% by mass or more and 90% by mass or less of other fibers, and the fibers are integrated by entanglement with each other. The water-repellent cellulose is biodegradable, and the "other fibers" are described as synthetic fibers containing biomass materials and biodegradable synthetic fibers. It is disclosed that a wiper can be provided which has excellent dirt collection properties and also has less shedding. Furthermore, for example, Patent Document 2 discloses a method for producing a nonwoven fabric using only biomass raw materials, which comprises mixing a layered silicate with a polylactic acid polymer so that the layered silicate is 1 to 5 parts by mass per 100 parts by mass of the polylactic acid polymer, melt-spinning the polylactic acid polymer mixed with the layered silicate by a spunbonding method, accumulating the obtained long fibers into a web, and then passing the obtained web through a thermal embossing device to partially thermocompress the web. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2023-101408 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-81902 Summary of the Invention [Problem to be solved by the invention]

[0009] However, conventional nonwoven fabrics made from biomass raw materials have problems, such as large sheet deformation due to friction during wiping, resulting in poor wiping performance, and differences in elongation between the machine and cross directions. For example, when wetted with water, they shrink significantly in the cross direction, resulting in dimensional changes during product use, resulting in a poor user experience. Furthermore, they may not have a sufficient oil absorption rate for wiping away oily materials such as machine oil. The present invention has been made in light of these circumstances, and aims to provide a composite nonwoven fabric made from polylactic acid (PLA), a biodegradable biomass material, that has a low environmental impact, provides a good user experience during wiping and when wetted with water, and has a sufficient oil absorption rate. [Means for solving the problem]

[0010] The inventors have conducted extensive research and have found that in a composite nonwoven fabric obtained by laminating a spunbonded nonwoven fabric containing polylactic acid (PLA) with a pulp fiber web and integrating them by hydroentangling, by setting the content ratio of polylactic acid (PLA) in the spunbonded nonwoven fabric, the basis weight and the transverse elongation at break of the composite nonwoven fabric all within predetermined ranges, a composite nonwoven fabric can be obtained that has a low environmental impact, a good feel when wiping and when wetted with water, and a sufficient oil absorption rate, and has thus completed the present invention.

[0011] (1) The first aspect of the present invention is a composite nonwoven fabric obtained by laminating a spunbonded nonwoven fabric containing polylactic acid (PLA) and a pulp fiber web and integrating them by hydroentangling, wherein the content of polylactic acid (PLA) in the spunbonded nonwoven fabric is 10% or more, and the basis weight of the composite nonwoven fabric is 40.0 g / m. 2 More than 160.0g / m 2 The composite nonwoven fabric is characterized by having a cross-directional elongation of less than 75%, an oil absorption rate of the pulp fiber web laminated surface of less than 95.0 seconds.

[0012] (2) A second aspect of the present invention is a composite nonwoven fabric according to (1), characterized in that the ratio of the breaking elongation in the longitudinal direction to the breaking elongation in the transverse direction of the composite nonwoven fabric (breaking elongation in the longitudinal direction / breaking elongation in the transverse direction) is 0.40 or more and 1.00 or less.

[0013] (3) A third aspect of the present invention is the composite nonwoven fabric according to (1), wherein the basis weight of the composite nonwoven fabric is 150.0 g / m 2 It is characterized in that it is less than.

[0014] (4) The fourth aspect of the present invention is a composite nonwoven fabric according to (1), characterized in that the content of polylactic acid (PLA) contained in the spunbond nonwoven fabric is 20% or more.

[0015] (5) The fifth aspect of the present invention is a composite nonwoven fabric according to (1), characterized in that the content of polylactic acid (PLA) contained in the spunbond nonwoven fabric is 50% or more.

[0016] (6) The sixth aspect of the present invention is the composite nonwoven fabric according to (1), wherein the basis weight of the composite nonwoven fabric is 45.0 g / m 2 As described above, the pulp fiber web is characterized in that the oil absorption rate of the laminated surface is less than 90.0 seconds.

[0017] (7) A seventh aspect of the present invention is the composite nonwoven fabric according to (1), characterized in that the thickness of the composite nonwoven fabric is 0.40 mm or more and 1.00 mm or less. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a composite nonwoven fabric that uses polylactic acid (PLA), a biodegradable biomass material, has a low environmental impact, provides a good feel when wiping or when wetted with water, and has a sufficient oil absorption rate. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist. The MD direction of the composite nonwoven fabric is the machine direction in which the composite nonwoven fabric is made, and the CD direction is the cross direction perpendicular to the machine direction.

[0020] <Composite nonwoven fabric> The composite nonwoven fabric according to this embodiment is formed by laminating a spunbond nonwoven fabric containing polylactic acid (PLA) and a pulp fiber web, and integrating them by hydroentangling.

[0021] (Polylactic acid (PLA)) The polylactic acid that can be used in this embodiment is a polymer formed by multiple ester bonds of lactic acid. Lactic acid exists in two forms: L- and D-forms, due to the difference in the configuration of the functional group bonded to one asymmetric carbon. Therefore, polylactic acid can be one in which D- or L-monomer units are bonded almost exclusively, or one in which D- and L-monomer units are bonded together. Furthermore, the D- and L-monomer units can be bonded randomly, alternately, or in blocks. Any of these can be used. However, from the standpoint of strength, heat resistance, etc., polylactic acid containing 95% or more by mass of L-monomer units is preferred. The molecular weight of polylactic acid is not particularly limited as long as it can be used to form a spunbonded nonwoven fabric, but polylactic acid with an Mw of 50,000 or more is preferred.

[0022] (Polylactic acid (PLA) content ratio and other fibers in spunbond nonwoven fabric) In this embodiment, the content of polylactic acid (PLA) in the spunbond nonwoven fabric is 10% or more. Preferably, the content is 20% or more, and more preferably, the content is 50% or more. By making the content of polylactic acid (PLA) in the spunbond 10% or more, a composite nonwoven fabric with a low environmental impact can be obtained. The spunbond nonwoven fabric may further contain synthetic fibers such as nylon, vinylon, polyester, acrylic, polyethylene, polystyrene, and polypropylene in addition to polylactic acid.

[0023] <Pulp fiber> Web The pulp fiber web preferably comprises fibers of one or more types of bleached softwood kraft pulp (NBKP) selected from the group consisting of radiata pine, slash pine, southern pine, lodgepole pine, spruce, and Douglas fir. In addition to softwood bleached kraft pulp (NBKP), the web may also contain common pulp fibers such as hardwood bleached kraft pulp (LBKP). However, the web preferably contains both softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP). The NBKP to LBKP ratio in the pulp fiber is preferably 50:50 to 100:0, more preferably 70:30 to 100:0, even more preferably 90:10 to 100:0, and most preferably 100:0. The pulp fiber web may also contain recycled paper pulp, non-wood pulp, deinked pulp, recycled paper from paper cartons for liquid beverages, and the like.

[0024] (Basis weight of hybrid nonwoven fabric and spunbond nonwoven fabric) The basis weight of the composite nonwoven fabric in this embodiment is 40.0 g / m 2 More than 160.0g / m 2 The lower limit of the basis weight of the composite nonwoven fabric is 45.0 g / m 2 It is preferable that the content is 50.0 g / m or more. 2 The upper limit is more preferably 150.0 g / m or more. 2 Preferably, the weight is 145.0 g / m or less. 2By setting the basis weight of the composite nonwoven fabric within the above range, the sheet stretching is suppressed and the composite nonwoven fabric can have a high oil absorption rate. The lower limit of the basis weight of the spunbond nonwoven fabric is 10.0 g / m 2 More than 12.0 g / m is preferable. 2 More preferably, 14.0 g / m or more 2 The upper limit of the basis weight of the spunbond nonwoven fabric is 50.0 g / m 2 Preferably, it is 45.0 g / m or less. 2 More preferably, it is 40.0 g / m or less. 2 It is more preferable that: By ensuring that the basis weight of the spunbond nonwoven fabric is within the above range, the sheet is prevented from stretching and has a good oil absorption rate. The basis weight of both the composite nonwoven fabric and the spunbond nonwoven fabric is measured in accordance with JIS P 8124.

[0025] (Thickness of composite nonwoven fabric) In this embodiment, the thickness of the composite nonwoven fabric is preferably 0.40 mm or more and 1.00 mm or less. The lower limit of the thickness of the composite nonwoven fabric is more preferably 0.42 mm or more, and even more preferably 0.45 mm or more. The upper limit of the thickness of the composite nonwoven fabric is more preferably 0.90 mm or less, and even more preferably 0.80 mm or less. By keeping the thickness within the above numerical range, it is possible to suppress the elongation of the sheet and improve the oil absorption rate. The thickness of the composite nonwoven fabric is 37.85gf / cm using a Peacock paper thickness gauge. 2 The measurement is carried out under a load of .

[0026] (Oil absorption speed) The oil absorption rate of the surface of the composite nonwoven fabric on which the pulp fibers are laminated is less than 95.0 seconds, preferably less than 85.0 seconds, and more preferably less than 75.0 seconds. The oil absorption rate is measured using oil (industrial gear oil: viscosity ISO VG 100) instead of water in the water absorption rate test specified in JIS L 1907. The oil absorption rate can be adjusted to a desired range by adjusting the type of synthetic fiber contained in the spunbond nonwoven fabric, the basis weight of the spunbond nonwoven fabric, and the basis weight of the pulp content.

[0027] (Elongation at break in the cross direction of composite nonwoven fabric) The composite nonwoven fabric has a breaking elongation in the transverse direction of less than 75%, and more preferably has a breaking elongation in the transverse direction of less than 70%. By setting the breaking elongation in the transverse direction of the composite nonwoven fabric within the above range, the sheet is less likely to deform during wiping, making it possible to provide a composite nonwoven fabric that is easy to handle. The tensile strength and elongation at break in the transverse and longitudinal directions of the composite nonwoven fabric are measured using a tensile tester using 25 mm wide test pieces cut from the composite nonwoven fabric. The measurement conditions are a chuck distance of 100 mm, a tensile speed of 300 mm / min, and an average value of four measurements (n=4). In this case, the transverse direction of the composite nonwoven fabric refers to the direction parallel to the CD direction. The desired range of elongation at break in the transverse direction can be achieved by adjusting the type of synthetic fiber contained in the spunbond nonwoven fabric, the basis weight of the spunbond nonwoven fabric, and the basis weight of the pulp content.

[0028] (Elongation at break in the longitudinal direction / Elongation at break in the transverse direction) The ratio of the breaking elongation in the longitudinal direction to the breaking elongation in the transverse direction of the composite nonwoven fabric (breaking elongation in the longitudinal direction / breaking elongation in the transverse direction) is preferably 0.40 or more and 1.00 or less. The lower limit of the ratio of the breaking elongation in the longitudinal direction to the breaking elongation in the transverse direction of the composite nonwoven fabric is more preferably 0.50 or more. Due to the characteristics of the composite nonwoven fabric, the ratio of the breaking elongation in the longitudinal direction to the breaking elongation in the transverse direction is generally 1.00 or less. When the ratio of the breaking elongation in the longitudinal direction to the breaking elongation in the transverse direction of the composite nonwoven fabric is within the above numerical range, the balance of the elongations in the longitudinal and transverse directions is good, and a composite nonwoven fabric can be obtained that exhibits little dimensional change in the transverse direction when wetted and used, and has a good feel when used.

[0029] <Method of manufacturing composite nonwoven fabric> The composite nonwoven fabric according to this embodiment can be manufactured by laminating a spunbond nonwoven fabric and a pulp fiber web together and integrating them by hydroentangling. The hydroentangling integration process is described in detail in, for example, Japanese Patent No. 6758116. As a method for forming a web of pulp fibers, the air-laid method is preferred from the viewpoint of water absorption. I wish.

[0030] The composite nonwoven fabric produced by the above process is preferably used for daily uses such as paper towels and kitchen towels, and for industrial uses such as wipers and cloths. In particular, since the sheet has reduced elongation and an excellent oil absorption rate, it is preferably used for wipers to wipe off oil from machines, etc. However, there are no limitations on the use as long as it is a mass-produced product for which consideration must be given to the environmental impact and is used to wipe off dirt and moisture.

[0031] As described above, according to the present embodiment, it is possible to provide a composite nonwoven fabric that contains polylactic acid (PLA), which has a low environmental impact, a good feel when used for wiping and when wetted with water, and a high oil absorption rate. [Example]

[0032] The present invention will be explained in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples in any way.

[0033] Composite nonwoven fabrics of Examples 1 to 8 and Comparative Examples 1 to 7 were produced under the conditions shown in Tables 1 and 2, and the following evaluations were carried out. Among the abbreviations shown in Tables 1 and 2, "PP" means polypropylene. Measurement of each parameter other than the evaluations below was carried out according to the standards or measurement methods described above. All measurements according to the standards or measurement methods described above were carried out indoors at a temperature of 23°C and a humidity of 50% RH.

[0034] (Feel when wiping) Regarding the feel of the composite nonwoven fabric when wiping, if there was no problem with the fit to the hand and the sheet shape retention when wiping the rubber plate, it was given a rating of "3," if better than this it was given a rating of "4," if slightly worse than 3 it was given a rating of "2," and if worse it was given a rating of "1." The rubber plate used was plain rubber (Matec chloroprene rubber, 300 x 300 mm).

[0035] (Usability when wet) Regarding the feel when the composite nonwoven fabric was wetted with water, if there were no problems with the fit to the hand and the sheet shape retention, it was given a rating of "3", if it was better than this, it was given a rating of "4", if it was slightly worse than 3, it was given a rating of "2", and if it was worse, it was given a rating of "1".

[0036] (Oil absorption performance) Based on the results of the oil absorption rate of the composite nonwoven fabric on the surface on which the pulp fiber web was laminated, evaluation was made according to the following criteria. 5: The oil absorption rate of the composite nonwoven fabric on the surface where the pulp fiber web is laminated is less than 75 seconds 4: The oil absorption rate of the composite nonwoven fabric on the surface where the pulp fiber web is laminated is 75 seconds or more and less than 85 seconds 3: The oil absorption rate of the composite nonwoven fabric on the surface where the pulp fiber web is laminated is 85 seconds or more and less than 95 seconds 2: The oil absorption rate of the composite nonwoven fabric on the surface where the pulp fiber web is laminated is 95 seconds or more and less than 105 seconds 1: The oil absorption rate of the composite nonwoven fabric on the surface where the pulp fiber web is laminated is 105 seconds or more

[0037] Tables 1 and 2 show the conditions and evaluation results for each example and each comparative example.

[0038] [Table 1]

[0039] [Table 2]

[0040] From the above, the nonwoven fabrics of Comparative Examples 1 to 7 received a rating of 1 or 2, whereas the nonwoven fabrics of Examples 1 to 8 received no rating of 1 or 2 and all received a rating of 3 or higher. This confirms that the present invention provides a composite nonwoven fabric using polylactic acid (PLA), a biodegradable biomass material, which has a low environmental impact, a good feel when wiping and when wetted with water, and a sufficient oil absorption rate.

Claims

1. A composite nonwoven fabric obtained by laminating a spunbond nonwoven fabric containing polylactic acid (PLA) and a pulp fiber web and integrating them by hydroentangling, The content of polylactic acid (PLA) in the spunbond nonwoven fabric is 10% or more, and the basis weight of the composite nonwoven fabric is 40.0 g / m ２ 160.0g / m or more ２ a breaking elongation in the transverse direction of less than 75%; and an oil absorption rate of the pulp fiber web laminated surface of less than 95.0 seconds.

2. 2. The composite nonwoven fabric according to claim 1, characterized in that the ratio of the breaking elongation in the machine direction to the breaking elongation in the transverse direction of the composite nonwoven fabric (breaking elongation in the machine direction / breaking elongation in the transverse direction) is 0.40 or more and 1.00 or less.

3. The basis weight of the composite nonwoven fabric is 150.0 g / m ２ The composite nonwoven fabric according to claim 1, wherein the thickness is less than 1 / 2 mm.

4. 2. The composite nonwoven fabric according to claim 1, wherein the spunbond nonwoven fabric contains 20% or more of polylactic acid (PLA).

5. 2. The composite nonwoven fabric according to claim 1, wherein the spunbond nonwoven fabric contains 50% or more of polylactic acid (PLA).

6. The basis weight of the composite nonwoven fabric is 45.0 g / m ２ 2. The composite nonwoven fabric according to claim 1, wherein the pulp fiber web layer has an oil absorption rate of less than 90.0 seconds.

7. 2. The composite nonwoven fabric according to claim 1, wherein the thickness of the composite nonwoven fabric is 0.40 mm or more and 1.00 mm or less.

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