Long fiber nonwoven fabric, method for producing the same, and process protection material

Abstract

The present invention provides a long fiber nonwoven fabric which is excellent in surface smoothness and followability to a conveyor or the like, and which can be used continuously. The present invention relates to a long fiber nonwoven fabric which is a long fiber nonwoven fabric composed of fibers in which a thermoplastic resin is a main component, and which has a surface roughness Rz of 25.0 μm or more and 50.0 μm or less on both surfaces z , and an absolute value of a difference between the surface roughness Rz of one surface and the surface roughness Rz of the other surface is 4.0 μm or more and 10.0 μm or less. The present invention also relates to a method for manufacturing a long fiber nonwoven fabric, and a process protection material including the long fiber nonwoven fabric. z z ​​

Description

[0001] This application is based on Japanese Patent Application No. 2023-025789 filed on February 22, 2023, the entire contents of which are hereby incorporated by reference. In addition, all references cited herein are incorporated by reference in their entirety. TECHNICAL FIELD

[0002] The present application relates to a long fiber nonwoven fabric and a manufacturing method thereof, and to a process protection material including the long fiber nonwoven fabric. BACKGROUND

[0003] Generally, in the manufacturing process, a belt conveyor or the like is often used when an intermediate product is carried in the horizontal direction. Among them, in the case of a precision part or the like that must be prevented from being damaged during the carrying, in order to prevent the carried member from slipping due to vibration or the like during the carrying, a sheet member as a process protection material can be arranged between the conveyor and the member, or the surface of the conveyor itself can be used as a sheet member, and the like, so that the member is carried while being fixed by suction. For such a sheet member, surface smoothness for not damaging the carried member, and followability to the conveyor or the like for not floating the sheet member during the carrying are required.

[0004] As a material used in such a sheet member, synthetic paper is sometimes used, and as such synthetic paper, for example, in Patent Literature 1, a synthetic paper in which a first layer including polyester fibers and a second layer including fibers having at least a portion of a low-melting-point component and polyester fibers are integrated is proposed, and in the synthetic paper, both the first layer and the second layer include a certain amount of low-orientation polyester fibers having a birefringence of a certain value or less.

[0005] Prior Art Documents

[0006] Patent Literature

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 59-228100 SUMMARY

[0008] Problems to be Solved by the Invention

[0009] However, the synthetic paper as disclosed in Patent Literature 1 is sometimes composed of short fibers, so that the number of fiber sticking points increases. Therefore, there is a problem that fluffing is easy, and sometimes dust or the like thereof is mixed in the manufacturing process, and causes damage to precision parts or the like.

[0010] Therefore, the present application is completed in view of the above-described circumstances, and an object thereof is to provide a long fiber nonwoven fabric that is excellent in surface smoothness and followability to a conveyor or the like, and can be used continuously.

[0011] Technical Means to Solve the Problem

[0012] The inventors have conducted repeated research to achieve the aforementioned objective, and have obtained the following insights: By producing a long-fiber nonwoven fabric in which the surface roughness of both sides of the long-fiber nonwoven fabric is set within a specific range, and the absolute value of the difference between the surface roughness of one surface and the surface roughness of the other surface is set within a specific range, the long-fiber nonwoven fabric not only exhibits smoothness and excellent mechanical strength, but also improves its tracking ability to conveyors and the like. Furthermore, it has been determined that process protective materials containing this long-fiber nonwoven fabric also exhibit excellent wear resistance and can be reused without linting.

[0013] This invention is based on these insights, and the following invention is provided according to this invention.

[0014] [1] A long-fiber nonwoven fabric, which is a long-fiber nonwoven fabric composed of fibers with thermoplastic resin as the main component, wherein the surface roughness R of both sides of the long-fiber nonwoven fabric is... z The surface roughness R of one of the surfaces is greater than 25.0 μm and less than 50.0 μm. z The surface roughness R of the other surface z The absolute value of the difference is greater than 4.0 μm and less than 10.0 μm.

[0015] [2] According to the long fiber nonwoven fabric described in [1], the area ratio of the fiber void portion of the long fiber nonwoven fabric is more than 1.0% and less than 15.0%.

[0016] [3] According to the long fiber nonwoven fabric of [1] or [2], wherein the fiber is a composite fiber of a low melting point polymer arranged around a high melting point polymer, the low melting point polymer having a melting point lower than that of the high melting point polymer.

[0017] [4] The long-fiber nonwoven fabric according to any one of [1] to [3], wherein the apparent density of the long-fiber nonwoven fabric is 0.40 g / cm³. 3 Above and 0.75g / cm 3 the following.

[0018] [5] The long-fiber nonwoven fabric according to any one of [1] to [4], wherein the unit area weight of the long-fiber nonwoven fabric is 40 g / m². 2 Above and 75g / m 2 the following.

[0019] [6] A method of manufacturing a long fiber nonwoven fabric according to any one of the [1] to [5], which is a method of manufacturing the long fiber nonwoven fabric according to any one of the [1] to [5], and which sequentially performs: a process of spinning a thermoplastic resin from a spinning hole of a spinneret, further performing suction stretching, thereby obtaining a long fiber; a process of capturing the long fiber onto a moving net conveyor, thereby forming a fiber web; a process of preheating by bringing a heating surface into contact with only one surface of the fiber web, thereby obtaining a preheated fiber web; and a process of heat-bonding the preheated fiber web by a pair of flat rolls, wherein a spinning speed in the suction stretching is 3,000 m / min or more and 6,000 m / min or less, in the preheating, a temperature of the heating surface is a temperature of 30°C or more and 110°C or less lower than a melting point of the thermoplastic resin, and a line pressure of the heating surface is 1 N / cm or more and 100 N / cm or less, and in the heat-bonding, a surface temperature of the pair of flat rolls is a temperature of 30°C or more and 70°C or less lower than the melting point of the thermoplastic resin, and a line pressure of the pair of flat rolls is 100 N / cm or more and 900 N / cm or less.

[0020] [7] A method of manufacturing a long fiber nonwoven fabric according to any one of the [1] to [5], which is a method of manufacturing the long fiber nonwoven fabric according to any one of the [1] to [5], and which sequentially performs: a process of spinning a high-melting-point polymer and a low-melting-point polymer having a melting point of 10°C or more and 110°C or less lower than a melting point of the high-melting-point polymer from a spinning hole of a composite spinneret, further performing suction stretching, thereby obtaining a composite fiber, i.e., a long fiber, in which the low-melting-point polymer is provided around the high-melting-point polymer; a process of capturing the long fiber onto a moving net conveyor, thereby forming a fiber web; a process of preheating by bringing a heating surface into contact with only one surface of the fiber web, thereby obtaining a preheated fiber web; and a process of heat-bonding the preheated fiber web by a pair of flat rolls, wherein a spinning speed in the suction stretching is 3,000 m / min or more and 6,000 m / min or less, in the preheating, a temperature of the heating surface is a temperature of 30°C or more and 110°C or less lower than a melting point of the low-melting-point polymer, and a line pressure of the heating surface is 1 N / cm or more and 100 N / cm or less, and in the heat-bonding, a surface temperature of the pair of flat rolls is a temperature of 30°C or more and 70°C or less lower than the melting point of the low-melting-point polymer, and a line pressure of the pair of flat rolls is 100 N / cm or more and 900 N / cm or less.

[0021] [8] A process protection material comprising the long fiber nonwoven fabric according to any one of the [1] to [5].

[0022] Effects of the Invention

[0023] According to the present invention, a long-fiber nonwoven fabric with excellent surface smoothness and conformability to conveyors, etc., and which can withstand continuous use, can be provided. Attached Figure Description

[0024] Figure 1 This is a cross-sectional conceptual diagram illustrating the structure of an apparatus for evaluating a long-fiber nonwoven fabric as a process protection material in accordance with one embodiment of the present invention.

[0025] Figure 2 This is a cross-sectional conceptual diagram illustrating and explaining the structure of a long fiber nonwoven fabric manufacturing apparatus according to an embodiment of the present invention.

[0026] Explanation of icon numbers

[0027] 1: Test piece

[0028] 2: Transporting components

[0029] 3: Belt Conveyor

[0030] 4: Sending organization

[0031] 5: Spinneret

[0032] 6: Injector

[0033] 7: Mesh Belt Conveyor

[0034] 8: Heated surface

[0035] 9: Flat roller

[0036] 10: The thermoplastic resin produced

[0037] 11: Fiber mesh

[0038] 12: Long-fiber nonwoven fabric

[0039] 13: Arrow indicating the direction of fiber web transport. Detailed Implementation

[0040] According to one embodiment of the present invention (hereinafter also referred to as "this embodiment"), the long-fiber nonwoven fabric is a long-fiber nonwoven fabric containing fibers with thermoplastic resin as the main component, wherein the surface roughness R of both sides of the long-fiber nonwoven fabric is... z The surface roughness R of one of the surfaces is greater than 25.0 μm and less than 50.0 μm. z The surface roughness R of the other surface zThe absolute value of the difference is 4.0 μm or more and 10.0 μm or less. Hereinafter, its constituent components will be described in detail, but the present invention is not limited to the scope of the following description as long as it does not depart from its spirit, and various modifications can be made without departing from the spirit of the present invention.

[0041] (Fibers with thermoplastic resin as the main component)

[0042] The long-fiber nonwoven fabric of this embodiment is a long-fiber nonwoven fabric containing fibers with thermoplastic resin as the main component. Here, in this embodiment, "with thermoplastic resin as the main component" means that the mass of the thermoplastic resin is more than 50% by mass relative to the total mass of the fiber.

[0043] Examples of thermoplastic resins include polyesters, polyamides, polyolefins, or mixtures or copolymers thereof. Polyesters are preferred due to their superior durability, including mechanical strength, heat resistance, water resistance, and chemical resistance.

[0044] Polyesters contain dicarboxylic acid and diol components. As dicarboxylic acid components, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and phthalic acid can be used; aliphatic dicarboxylic acids such as adipic acid and sebacic acid can be used; and alicyclic dicarboxylic acids such as cyclohexanecarboxylic acid can be used. As diol components, ethylene glycol, diethylene glycol, and polyethylene glycol can be used.

[0045] Specific examples of polyesters include: polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polylactic acid (PLA), polybutylene succinate (PBS), and their copolymers.

[0046] Within the scope of not impairing the effects of the present invention, additives such as crystallizing nucleating agents, matting agents, lubricants, pigments, mildew inhibitors, antibacterial agents, flame retardants, and hydrophilic agents may be added to the thermoplastic resin of this embodiment.

[0047] Furthermore, if the thermoplastic resin of this embodiment contains metal oxides such as titanium oxide, the thermal conductivity of the fiber web is enhanced during the manufacturing stage when the preheated fiber web is thermally bonded, as described later. This improves the adhesion within the fiber web, thereby enabling the production of long-fiber nonwoven fabrics with superior mechanical strength.

[0048] Furthermore, if the thermoplastic resin of this embodiment contains aliphatic diamides such as ethylene bis-stearamide and / or alkyl-substituted aliphatic monoamides, then during its manufacturing stage, the demolding property between the pair of flat rollers used in the thermal bonding of the preheated fiber web described later and the preheated fiber web becomes higher, which can improve the bonding stability within the fiber web and further increase the softness, thereby producing a long-fiber nonwoven fabric with excellent followability to conveyors, etc. when used as a process protection material.

[0049] Furthermore, these additives can be in the form of adhering to the surface of the fiber, which is mainly composed of thermoplastic resin as described later.

[0050] The melting point of the thermoplastic resin in this embodiment is preferably in the range of 100°C or higher and 320°C or lower. The lower limit of this range is preferably 100°C or higher, more preferably 120°C or higher, even more preferably 140°C or higher, and particularly preferably 160°C or higher, thereby obtaining the desired thermal adhesion and forming a high-density, smooth long-fiber nonwoven fabric. On the other hand, the upper limit of this range is preferably 320°C or lower, more preferably 300°C or lower, even more preferably 280°C or lower, and particularly preferably 250°C or lower, thereby making the composite fibers softer and forming a long-fiber nonwoven fabric that is easier to follow conveyors, etc.

[0051] The fiber used in this embodiment is preferably a composite fiber consisting of a high-melting-point polymer surrounded by a low-melting-point polymer, wherein the low-melting-point polymer has a melting point lower than that of the high-melting-point polymer. By employing this type of composite fiber, the fibers can be further bonded together to form a smooth and excellent long-fiber nonwoven fabric, which, when used as a process protective material, can prevent damage to the transported components.

[0052] The difference between the melting point of the high-melting-point polymer and the melting point of the low-melting-point polymer (hereinafter sometimes simply referred to as the "melting point difference") is preferably 10°C or more and 110°C or less. In other words, it is preferable to use a low-melting-point polymer with a melting point that is 10°C or more and 110°C lower than the melting point of the high-melting-point polymer. The melting point difference is preferably 10°C or more, more preferably 20°C or more, and even more preferably 30°C or more, thereby forming a long-fiber nonwoven fabric with sufficiently excellent adhesion. In addition, the melting point difference is preferably 110°C or less, more preferably 100°C or less, and even more preferably 90°C or less, so that the low-melting-point polymer will not fuse to the rollers used for thermal bonding, thus reducing productivity, thereby forming a long-fiber nonwoven fabric with excellent breathability.

[0053] In this embodiment, the melting point of the high-melting-point polymer in the composite fiber is preferably in the range of 160°C or higher and 320°C or lower. The melting point of the high-melting-point polymer in the composite fiber is preferably 160°C or higher, more preferably 170°C or higher, and even more preferably 180°C or higher, thereby forming a long-fiber nonwoven fabric with excellent morphological stability or durability. Furthermore, if the melting point of the high-melting-point polymer in the composite fiber is 320°C or lower, more preferably 300°C or lower, and even more preferably 280°C or lower, the composite fiber becomes softer, forming a long-fiber nonwoven fabric that is easier to follow conveyors, etc.

[0054] On the other hand, regarding the melting point of the low-melting-point polymer in the composite fiber, it is preferably in the range of 100°C or higher and 250°C or lower, while ensuring the difference in melting points. The melting point of the low-melting-point polymer in the composite fiber is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher, thereby obtaining the desired thermal adhesion and forming a high-density and smooth long-fiber nonwoven fabric. Furthermore, the melting point of the low-melting-point polymer in the composite fiber is preferably 250°C or lower, more preferably 240°C or lower, and even more preferably 230°C or lower, thereby making the composite fiber softer and forming a long-fiber nonwoven fabric that is easier to follow conveyors, etc.

[0055] Furthermore, in this embodiment, regarding the melting point of the thermoplastic resin, the temperature at which an extreme value is obtained in the melt endothermic curve is defined as the melting point of the thermoplastic resin. This melt endothermic curve is obtained using a differential scanning calorimeter (e.g., a PerkinElmer "DSC-2" type) at a heating rate of 20°C / min and a measurement temperature range of 30°C to 350°C. Additionally, for resins whose melt endothermic curves do not show extreme values ​​in the differential scanning calorimeter, the resin is heated on a hot plate, and the melting temperature is determined by microscopic observation and defined as the melting point.

[0056] When the thermoplastic resin is polyester, combinations of high-melting-point polymers and low-melting-point polymers (sometimes described below in the order of high-melting-point polymer / low-melting-point polymer) can be listed, for example: combinations of PET / PBT, PET / PTT, PET / polylactic acid, and PET / copolymer PET, etc. Among these, the combination of PET / copolymer PET is preferred in terms of excellent spinnability. Furthermore, isophthalic acid copolymer PET is preferred as the copolymer component of copolymer PET in terms of particularly excellent spinnability.

[0057] Regarding the composite morphology of the composite fibers, examples include concentric core-sheath type, eccentric core-sheath type, and island type, among which the concentric core-sheath type is preferred for uniformly and firmly fusing the fibers together. Furthermore, as for the cross-sectional shape of this composite fiber, examples include circular cross-section, flat cross-section, polygonal cross-section, multi-leaf cross-section, and hollow cross-section, among which the circular cross-section is the preferred shape for the composite fiber.

[0058] Furthermore, regarding the content ratio of high-melting-point polymers to low-melting-point polymers in fibers with thermoplastic resins as the main component, the preferred mass ratio is in the range of 90:10 to 30:70, and more preferably in the range of 83:17 to 40:60. The mass percentage of high-melting-point polymers relative to the total mass of high-melting-point and low-melting-point polymers contained in the fiber (abbreviated as high-melting-point polymer content ratio) is preferably 30% by mass or more and 90% by mass or less, more preferably 40% by mass or more and 83% by mass or less, thereby forming a long-fiber nonwoven fabric with excellent thermal stability. On the other hand, the mass percentage of low-melting-point polymers relative to the total mass of high-melting-point and low-melting-point polymers contained in the fiber (abbreviated as low-melting-point polymer content ratio) is 10% by mass or more and 70% by mass or less, more preferably 17% by mass or more and 60% by mass or less, thereby forming a long-fiber nonwoven fabric with excellent thermal adhesion, smoother surface, and higher density.

[0059] The average single fiber diameter of the fiber, which is mainly composed of thermoplastic resin, is preferably 10 μm or more and 24 μm or less. The average single fiber diameter is preferably 10 μm or more, more preferably 12 μm or more, and even more preferably 14 μm or more, thereby forming a long fiber nonwoven fabric with excellent mechanical strength.

[0060] On the other hand, the average single fiber diameter is preferably 24 μm or less, more preferably 22 μm or less, and even more preferably 20 μm or less, thereby forming a denser long fiber nonwoven fabric. As a result, the minute irregularities are reduced, and when used as a process protective material, damage to the transported components can be prevented.

[0061] Furthermore, even when multiple fibers are mixed, the single fiber diameter of the fibers, as determined by the following sequence, is preferably within the aforementioned range.

[0062] Furthermore, in this embodiment, the average single fiber diameter (μm) of the fiber with thermoplastic resin as the main component is set to a value calculated in the following order.

[0063] (1) Randomly collect 10 small samples (100mm×100mm) from long fiber nonwoven fabric.

[0064] (2) Take surface photographs at magnification of 500x or higher and 3000x or lower using a microscope (e.g., “VHX-D500” manufactured by KEYENCE Inc.), and randomly measure the diameter of 10 single fibers from each sample, for a total of 100 fibers.

[0065] (3) The arithmetic mean of the 100 measured values ​​is rounded to the nearest whole number to calculate the average single fiber diameter (μm).

[0066] Fibers with thermoplastic resin as the main component may contain not only thermoplastic resin, but also additives such as lubricants, mildew inhibitors, antibacterial agents, flame retardants, and hydrophilic agents.

[0067] (Long-fiber nonwoven fabric)

[0068] The long-fiber nonwoven fabric of this embodiment is composed of the aforementioned fibers. Furthermore, the surface roughness R of both sides of the long-fiber nonwoven fabric of this embodiment is... z The surface roughness R of both sides is greater than 25.0 μm and less than 50.0 μm. z The thickness is 25.0 μm or more, preferably 30.0 μm or more, and more preferably 35.0 μm or more, thereby forming a long-fiber nonwoven fabric with moderate unevenness on the surface. When used as a process protection material, it can fully absorb the conveyed components and transport the components without slippage between the conveyor and the conveyed components.

[0069] On the other hand, the surface roughness R of both sides z The micrometer is 50.0 μm or less, preferably 45.0 μm or less, and more preferably 40.0 μm or less, thereby forming a long-fiber nonwoven fabric with a denser surface. When used as a process protective material, it can prevent fuzzing caused by friction with the transported components.

[0070] To improve the surface roughness R of both sides of the long fiber nonwoven fabric z The range can be achieved by adjusting the surface temperature or linear pressure of a pair of flat rollers in the thermal bonding process of the manufacturing method of long fiber nonwoven fabric to the range described later.

[0071] In addition, the surface roughness R of one surface of the long fiber nonwoven fabric in this embodiment is... z Surface roughness R of another surface zThe absolute value of the difference (hereinafter sometimes simply referred to as "the absolute value of the surface roughness difference") is 4.0 μm or more and 10.0 μm or less. The absolute value of the surface roughness difference of the long fiber nonwoven fabric is 4.0 μm or more, preferably 5.0 μm or more, and more preferably 6.0 μm or more, thereby forming a long fiber nonwoven fabric with sufficient surface roughness difference. When used as a process protection material, it can transport components without slippage between the conveyor and the component being transported.

[0072] On the other hand, the absolute value of the difference in surface roughness is 10.0 μm or less, preferably 9.0 μm or less, and more preferably 8.0 μm or less, thereby forming a long-fiber nonwoven fabric with a moderate surface roughness difference. When used as a process protective material, it can suppress the fuzzing or cracking of the process protective material and prevent lint from getting into the conveyed components.

[0073] The absolute value of this surface roughness difference can be achieved by adjusting the temperature or linear pressure of the heating surface that contacts only one surface of the fiber web in the process of obtaining the preheated fiber web in the manufacturing method of long fiber nonwoven fabric, and the surface temperature or linear pressure of a pair of flat rollers in the thermal bonding process to the ranges described later.

[0074] Furthermore, the surface roughness (μm) and the difference in surface roughness (μm) of the long-fiber nonwoven fabric are calculated in the following order.

[0075] (1) Randomly collect 20 long fiber nonwoven fabrics of 10cm×10cm from each location.

[0076] (2) In any sampled nonwoven fabric, a surface roughness meter (e.g., the Surftest SJ-210 manufactured by Mitutoyo Co., Ltd.) was used to measure the surface roughness over a 21mm range relative to the width of the long-fiber nonwoven fabric sheet, according to the Japanese Industrial Standards (JIS) B0610:2001 "Geometrical Product Specification (GPS) - Surface Shape: Profile Curve Method - Definition and Representation of Rolling Circular Wavyness". The measurement was performed under the conditions of λc = 2.5mm, λs = 8μm, and a measurement speed of 0.5mm / s. The maximum height R at 20 points on each surface was measured in units of 0.1μm. z The determination.

[0077] (3) For the measured values, the values ​​are calculated by arithmetic mean on each surface, the second decimal place is rounded off, and the difference is set as the difference in surface roughness.

[0078] (4) In addition, the surface roughness of each surface is calculated by arithmetic average, and the second decimal place is rounded to obtain the surface roughness of the long fiber.

[0079] The area ratio of the fiber void portion of the long-fiber nonwoven fabric is preferably 1.0% or more and 15.0% or less. More preferably, it is 3.0% or more, and even more preferably 5.0% or more. This results in a long-fiber nonwoven fabric that simultaneously contains areas with a large amount of fiber and areas with a small amount of fiber. When used as a process protection material, this material can be fully drawn into a conveyor or similar device and transported without shifting the transported components. Conversely, the area ratio of the fiber void portion of the long-fiber nonwoven fabric is preferably 15.0% or less, more preferably 13.0% or less, and even more preferably 10.0% or less. This results in a long-fiber nonwoven fabric with homogeneous fiber density. When used as a process protection material, this prevents the process protection material from pilling or cracking, and also prevents damage to the transported components.

[0080] Furthermore, the area ratio of the fiber voids in the long-fiber nonwoven fabric is calculated in the following order.

[0081] (1) Randomly collect 10 long fiber nonwoven fabrics with a length of 30cm and a width of 21cm.

[0082] (2) Use a scanner (e.g., the DocuCentre-VI4471 multifunction printer manufactured by Fujifilm Business Innovation Co., Ltd.) to scan any collected nonwoven fabric at 300 dpi.

[0083] (3) Use image editing software (e.g., “GIMP Ver.2.10.30”, etc.) to binarize the scanned image with a threshold of 175 (when set to 256 levels of black: 0 ~ gray ~ white: 255, below 175 means black and above 176 means white).

[0084] (4) Using image analysis software (such as "Image J Ver.1.53e") after binarization, calculate the area ratio of blackening (fiber voids) at each measurement location.

[0085] (5) For the values ​​measured at each part, the arithmetic mean is calculated, the second decimal place is rounded off, and the result is set as the area ratio of the fiber voids of the long fiber nonwoven fabric.

[0086] The apparent density of the long-fiber nonwoven fabric is preferably 0.40 g / cm³.3 Above and 0.75g / cm 3 The apparent density is preferably 0.40 g / cm³. 3 The above, more preferably 0.42 g / cm³ 3 The above, and more preferably 0.45 g / cm³ 3 This process results in a long-fiber nonwoven fabric with minimal fuzzing, and its mechanical strength can be further improved. Furthermore, the apparent density of the long-fiber nonwoven fabric is 0.75 g / cm³. 3 The preferred value is 0.72 g / cm³. 3 The following is more preferably 0.70 g / cm³. 3 Therefore, a long-fiber nonwoven fabric with excellent process passability is formed, which will not float up when used as a process protection material during transportation.

[0087] Furthermore, the apparent density (g / cm³) of the long-fiber nonwoven fabric 3 The following values ​​are used: the unit area weight (g / m²) of the long-fiber nonwoven fabric, after unit conversion, is set to... 2 In addition to the thickness (mm) of the long-fiber nonwoven fabric mentioned later, the result (g / cm) 3 The value is calculated by rounding to the third decimal place. Here, the thickness (mm) of the long-fiber nonwoven fabric is calculated in the following order.

[0088] (1) Collect three long-fiber nonwoven fabrics with a width of 10cm in the length direction.

[0089] (2) Using a pressure head with a diameter of 10 mm, the thickness is measured at 10 points every 1 m along the width direction of the long fiber nonwoven fabric at equal intervals of 0.01 mm under a load of 10 kPa.

[0090] (3) Calculate the arithmetic mean of the measured values ​​obtained for the three long-fiber nonwoven fabrics. Then, round the arithmetic mean to the fourth decimal place for the three long-fiber nonwoven fabrics.

[0091] The preferred unit area weight of the long-fiber nonwoven fabric is 40 g / m². 2 Above and 75g / m 2 The preferred weight per unit area is 40 g / m². 2 The above, more preferably 45g / m 2 The above, and more preferably 50g / m 2 The above results in a long-fiber nonwoven fabric with excellent mechanical strength, which can prevent damage to the transported components when used as a protective material in the process.

[0092] On the other hand, the preferred weight per unit area is 75 g / m². 2 The following is more preferably 70g / m 2 The preferred value is 65g / m³. 2 The resulting long-fiber nonwoven fabric, which suppresses the decrease in air permeability, provides excellent suction and fixation of the transported components when used as a process protection material.

[0093] In addition, the unit area weight (g / m²) of the long fiber nonwoven fabric 2 The following steps are used to calculate it.

[0094] (1) Collect three 30cm×50cm long fiber nonwoven fabrics.

[0095] (2) Measure the mass of each sample separately, and convert the average value obtained into the mass per unit area (g / m²). 2 Round the first decimal place to the nearest whole number and calculate the weight per unit area.

[0096] The preferred air permeability of the long-fiber nonwoven fabric is 5cm. 3 / (cm 2 (seconds) or more and 30cm 3 / (cm 2 (seconds) or less. The preferred ventilation volume is 5 cm. 3 / (cm 2 • seconds or more, preferably 10 cm 3 / (cm 2 • seconds or more, and preferably 15cm 3 / (cm 2 (·seconds) or more, thus forming a long-fiber nonwoven fabric with a certain air permeability, which can make the conveyed components have excellent suction and fixation properties when used as a process protection material.

[0097] On the other hand, the ventilation volume is preferably 30 cm. 3 / (cm 2 · seconds or less, preferably 27cm 3 / (cm 2 (seconds) or less, and preferably 25cm 3 / (cm 2 The air permeability is less than 1 second, thus forming a long-fiber nonwoven fabric without excessive air permeability. When used as a process protection material, it can prevent damage to the conveyed components caused by excessive suction force on the conveyor.

[0098] (Process protection material)

[0099] The process protection material in this embodiment includes the long-fiber nonwoven fabric of this embodiment. Here, the process protection material refers to the material placed between the conveyor and the component during component handling to protect the component from direct contact with the conveyor, which could cause contamination, breakage, or damage, or to prevent chemicals or other substances applied to the component from adhering to the conveyor and contaminating subsequent components.

[0100] In this embodiment, the width of the process protection material is preferably the same as the width of the conveyor or a few centimeters narrower. By using this width, it is possible to prevent the process protection material from being rolled into the drive section of the conveyor.

[0101] (Manufacturing method of long fiber nonwoven fabric)

[0102] Next, the manufacturing method of the long-fiber nonwoven fabric of this embodiment will be described. The long-fiber nonwoven fabric of this embodiment is preferably manufactured by performing the following steps (a) to (d) in sequence.

[0103] (a) The process of spinning thermoplastic resin from the nozzle of a spinneret and then further drawing and stretching it to obtain long fibers.

[0104] (b) The process of collecting the long fibers onto a moving mesh belt conveyor to form a fiber web.

[0105] (c) A process of preheating the fiber web by making the heating surface contact only one of the surfaces of the fiber web.

[0106] (d) The process of thermally bonding the preheated fiber web using a pair of flat rollers.

[0107] Alternatively, the long-fiber nonwoven fabric of this embodiment is preferably manufactured by performing the following steps (a) to (d) in sequence.

[0108] (a) The process of spinning high-melting-point polymer and low-melting-point polymer from the nozzle of a composite spinneret and then further drawing and stretching them to obtain composite fibers, i.e. long fibers.

[0109] (b) The process of collecting the long fibers onto a moving mesh belt conveyor to form a fiber web.

[0110] (c) A process of preheating the fiber web by making the heating surface contact only one of the surfaces of the fiber web.

[0111] (d) The process of thermally bonding the preheated fiber web using a pair of flat rollers.

[0112] The following provides a more detailed description of each of the aforementioned processes.

[0113] (a) Process for obtaining long fibers

[0114] First, in this process, the thermoplastic resin is spun out from the nozzle of the spinneret.

[0115] Furthermore, when the fibers constituting the long-fiber nonwoven fabric are composite fibers consisting of a high-melting-point polymer surrounded by a low-melting-point polymer having a melting point lower than that of the high-melting-point polymer, the high-melting-point polymer and the low-melting-point polymer having a melting point 10°C or more but less than 110°C lower than that of the high-melting-point polymer are spun out from the extrusion orifice of the composite spinneret. In this case, it is preferable to melt each of the high-melting-point polymer and the low-melting-point polymer at a temperature above but below (melting point + 70°C) and melt-extrude them from a spinneret with a die temperature above but below (melting point + 70°C) to form a composite fiber, i.e., a long fiber, consisting of a high-melting-point polymer surrounded by a low-melting-point polymer. Furthermore, the high-melting-point polymer and the low-melting-point polymer can be controlled at different temperatures during melting and then controlled at the same temperature midway through melting.

[0116] Furthermore, the shape of the nozzle of the spinneret that extrudes molten thermoplastic resin is consistent with the cross-sectional shape of the fiber, and examples include: circular, elliptical, polygonal, multi-lobed, or combinations thereof. Among these, from the viewpoint of efficiently obtaining the bonding points between fibers and firmly bonding the fibers together by thermal bonding, a spinneret with a circular cross-section is a more preferred form.

[0117] Then, the thermoplastic resin spun by melt extrusion as described above is drawn and stretched through an ejector to form fibers. For drawing and stretching, air is generally used, and the spinning speed is preferably 3000 m / min or more and 6000 m / min or less. Making the spinning speed preferably 3000 m / min or more, more preferably 3500 m / min or more, and even more preferably 4000 m / min or more, allows for a higher degree of orientation and crystallization of the long fibers constituting the fiber web, preventing fiber shrinkage and wrinkling during preheating or heat bonding in subsequent processes, or reducing productivity by fusing thermoplastic resin, especially low-melting-point polymers, on heated rollers or the like.

[0118] On the other hand, the spinning speed is preferably 6000 m / min or less, more preferably 5500 m / min or less, and even more preferably 5000 m / min or less, thereby suppressing excessive orientation crystallization of the fibers and thus obtaining thermal adhesion that helps improve the mechanical strength of the spunbond nonwoven fabric.

[0119] (b) The process of forming a fiber web

[0120] In this process, the long fibers obtained through the aforementioned process are collected onto a moving mesh belt conveyor to form a fiber web. At this time, it is preferable to collect the long fibers by restricting their arrangement using a fiber opener. Specifically, it is more preferable to eject the fibers drawn in by the ejector from a slit-shaped fiber opener located at the bottom of the ejector. Furthermore, it is preferable to form the fiber web by accumulating the fibers on the moving mesh belt conveyor.

[0121] (c) Process for obtaining preheated fiber web

[0122] In the manufacturing method of long fiber nonwoven fabric of this embodiment, the heating surface is preheated by contacting only one surface of the fiber web obtained in the process to obtain a preheated fiber web.

[0123] For preheating, it is preferable to use a method that fuses the captured fiber web using a pair of upper and lower flat rollers, or to place a flat roller or heating plate above the mesh belt conveyor and fuse it between the mesh belt conveyor and this flat roller or heating plate. By setting the surface-back difference in this manner, good process passability is achieved when used as a process protection material.

[0124] The term "flat roller" used in these methods refers to a metal roller or elastic roller with a smooth surface. Furthermore, a pair of flat rollers refers to rollers that are paired with metal rollers, or rollers that are paired with elastic rollers. Here, "elastic roller" refers to a roller that incorporates a material with elasticity compared to a metal roller. Examples of elastic rollers include paper rollers (made of paper, cotton, or aramid paper), and resin rollers containing urethane resins, epoxy resins, silicone resins, polyester resins, and hard rubber, or mixtures thereof.

[0125] Furthermore, in this preheating process, when welding is performed using a pair of flat rollers, only one of the flat rollers becomes the heating surface. In one embodiment, this occurs when only one flat roller has a heating mechanism such as a heater and is heated to the temperature described later (the hot roller), while the other flat roller either does not have such a heating mechanism or, even if it does have a heating mechanism, has its heater switched off. In this embodiment, the term "heating surface" refers to the surface of the hot roller.

[0126] Furthermore, in this preheating process, when the flat roller is positioned above the mesh belt conveyor and preheating is performed between the mesh belt conveyor and the flat roller, the flat roller is preferably made of metal, and a heating mechanism such as a heater is provided only on the flat roller, and it is heated to the temperature described later. Moreover, this flat roller is a hot roller, and the surface of this hot roller is the "heating surface".

[0127] Furthermore, in this preheating process, when the heating plate is placed above the mesh belt conveyor and preheating is carried out between the mesh belt conveyor and the heating plate, the heating plate is preferably made of metal, and a heating mechanism such as a heater is provided only on the heating plate to heat it to the temperature described later. Moreover, the surface of the heating plate that contacts the fiber web is the "heating surface".

[0128] In the preheating process of this step, the temperature of the heating surface is 30°C to 110°C lower than the melting point of the thermoplastic resin (in the case where the fiber is a composite fiber of a high-melting-point polymer surrounded by a low-melting-point polymer having a lower melting point than the high-melting-point polymer, the melting point of the low-melting-point polymer is the value of the low-melting-point polymer). Furthermore, the linear voltage of the heating surface is 1 N / cm to 100 N / cm. By preheating under these conditions, heat is applied only to the fiber web on the heating surface, and crystallization of the fibers is promoted only at the fiber contact surfaces. After thermal bonding as described later, a surface roughness R can be achieved. z Nonwoven fabric with sufficient surface-back difference.

[0129] In particular, regarding the temperature range, it is preferably 30°C or more (set to [melting point - 30]°C or less) lower than the melting point of the thermoplastic resin (in the case where the fiber is a composite fiber of a high-melting-point polymer surrounded by a low-melting-point polymer having a melting point lower than that high-melting-point polymer, the melting point of the low-melting-point polymer is specified). This prevents the surface temperature of the fiber web on the heating surface from becoming too high, which would cause the fiber web to be removed by a pair of flat rollers during thermal bonding, allowing it to be transported to the next process. Furthermore, it is preferably 110°C or less (set to [melting point - 110]°C or more) lower than the melting point, and preferably 100°C or less (set to [melting point - 100]°C or more), thereby ensuring sufficient preheating of the fiber web on the heating surface.

[0130] On the other hand, regarding the range of the linear compression, the lower limit is set to 1 N / cm or more, preferably 5 N / cm or more, thereby ensuring sufficient preheating of the fiber web on the heating surface. On the other hand, regarding the range, the upper limit is set to 100 N / cm or less, preferably 50 N / cm or less, thereby suppressing heat transfer to the interior of the fiber web on the heating surface and preventing thermal crystallization, thus ensuring sufficient compression during thermal bonding.

[0131] (d) Thermal bonding process

[0132] In the method for manufacturing long-fiber nonwoven fabric according to this embodiment, a pair of flat rollers are used to thermally bond the preheated fiber web obtained in the process. In this thermal bonding, the surface temperature of the pair of flat rollers is 30°C to 70°C lower than the melting point of the thermoplastic resin (in the case where the fiber is a composite fiber of a high-melting-point polymer surrounded by a low-melting-point polymer having a melting point lower than that high-melting-point polymer, the melting point of the low-melting-point polymer is specified), and the linear pressure of the pair of flat rollers is 100 N / cm to 900 N / cm. By performing thermal bonding under these conditions, the preheated fiber web can be sufficiently thermally bonded, resulting in a desired smooth surface roughness, and the surface roughness R... z Nonwoven fabric with full face-back difference.

[0133] In particular, regarding the temperature range, it is preferably 30°C or more (set to [melting point - 30]°C or less) lower than the melting point of the thermoplastic resin (in the case where the fiber is a composite fiber of a high-melting-point polymer surrounded by a low-melting-point polymer having a lower melting point than the high-melting-point polymer, the melting point of the low-melting-point polymer is specified). This prevents the surface temperature of the pair of flat rollers from becoming too high, causing the preheated fiber web to wind onto the flat rollers, thus allowing it to be conveyed to the subsequent process. It is preferably 70°C or less (set to [melting point - 70]°C or more) lower than the melting point, preferably 60°C or less (set to [melting point - 60]°C or more), thereby ensuring that the preheated fiber web is sufficiently thermally bonded, resulting in a long-fiber nonwoven fabric with sufficient mechanical strength.

[0134] On the other hand, regarding the range of the linear pressure, the lower limit is set to 100 N / cm or more, preferably 500 N / cm or more, thereby allowing the preheated fiber web to be sufficiently thermally bonded, resulting in a long-fiber nonwoven fabric with the desired surface roughness. On the other hand, regarding the range, the upper limit is set to 900 N / cm or less, preferably 800 N / cm or less, thereby enabling less secure thermal bonding and suppressing partial film formation in the long-fiber nonwoven fabric.

[0135] (e) Manufacturing apparatus for long-fiber nonwoven fabrics

[0136] at last, Figure 2 An example of a manufacturing apparatus is shown for carrying out the manufacturing methods of long-fiber nonwoven fabrics illustrated in (a) to (d).

[0137] Long fibers are obtained by drawing and stretching thermoplastic resin 10 (which, as described above, can also be a high-melting-point polymer and a low-melting-point polymer) spun from the nozzle of spinneret 5 (as described above, spinneret 5 can also be a composite spinneret) using ejector 6. The long fibers are then collected onto a moving mesh conveyor 7 to form a fiber web 11. The fiber web 11 is then conveyed in the direction of arrow 13, indicating the conveying direction of the fiber web, so that the heating surface 8 contacts only one surface of the fiber web 11 for preheating, forming a preheated fiber web. This preheated fiber web is then thermally bonded using a pair of flat rollers 9 to finally obtain a long-fiber nonwoven fabric 12.

[0138] Of course, the device described is merely a preferred embodiment and is not limited to the scope described. Moreover, various modifications are naturally possible without departing from the spirit of the invention.

[0139] [Example]

[0140] Next, the nonwoven roller and its manufacturing method according to this embodiment will be specifically described based on examples. However, the present invention is not limited to these examples. In the determination of various physical properties, unless otherwise specified, the determinations are performed based on the methods described above.

[0141] [Determination Method]

[0142] (1) Inherent viscosity IV:

[0143] The intrinsic viscosity IV of polyethylene terephthalate resin was determined using the following method. 8 g of the sample was dissolved relative to 100 mL of o-chlorophenol, and the relative viscosity η was calculated using an Ostwald viscometer at 25°C using the following formula. r

[0144] η r =η / η0=(t×d) / (t0×d0)

[0145] (Here, η represents the viscosity of the polymer solution, η0 represents the viscosity of o-chlorophenol, t represents the drop time of the solution (seconds), and d represents the density of the solution (g / cm³).) 3 ), t0 represents the falling time of o-chlorophenol (seconds), and d0 represents the density of o-chlorophenol (g / cm³). 3 ))

[0146] Next, based on the relative viscosity η r The intrinsic viscosity IV is calculated using the following formula.

[0147] Intrinsic viscosity IV = 0.0242η r +0.2634.

[0148] (2) Melting point (°C):

[0149] Regarding the melting point of the thermoplastic resin used, it was measured under the stated conditions using a differential scanning calorimeter (TA Instruments "Q100"), and the average value of the endothermic peak temperature was calculated and set as the melting point of the measured object.

[0150] (3) Average single fiber diameter (μm)

[0151] The average single fiber diameter (μm) was measured and calculated using the method described above, using a "VHX-D500" microscope manufactured by KEYENCE Inc.

[0152] (4) Weight per unit area (g / m²) 2 ), thickness (mm), apparent density (g / cm³) 3 ):

[0153] The unit area weight, thickness, and apparent density of the long fiber nonwoven fabric were measured and calculated using the methods described above.

[0154] (5) Ventilation volume (cm) 3 / (cm 2 ·Second))

[0155] Regarding the air permeability of long-fiber nonwoven fabrics, the test was conducted according to JIS L1913:2010 "General Nonwoven Fabrics Test Methods" "6.8.1 Frazer Method", using a Textest FX3300 air permeability testing machine at a test pressure of 125 Pa on 10 sheets of fiber cut into 15 cm squares. The average value was then rounded to the second decimal place.

[0156] (6) Surface roughness R z (μm), surface roughness R z The absolute value of the difference

[0157] Surface roughness R of long fiber nonwoven fabric z (μm), surface roughness R z The absolute value of the difference is calculated using the method described above.

[0158] (7) Area percentage of fiber voids (%)

[0159] The percentage of the area of ​​the fiber voids in the long-fiber nonwoven fabric was calculated using the method described above, with a DocuCentre-VI4471 multifunction printer manufactured by Fujifilm Business Innovation Co., Ltd. as the scanner, GIMP Ver.2.10.30 as the image editing software, and ImageJVer.1.53e as the image analysis software.

[0160] (8) Evaluation as a process protection material

[0161] The long-fiber nonwoven fabric (comparative example 4 is short-fiber nonwoven fabric) was cut along the width direction. Test pieces with a width of 25 cm and a length of 55 m were collected from 2 points at both ends and 2 points in the center. The transport operation (8-1) was carried out, and the evaluation of its use as a process protection material was carried out according to the following 3 viewpoints (8-2) to (8-4).

[0162] (8-1)Transportation operation

[0163] Regarding transport, use Figure 1 The device shown in the cross-sectional conceptual diagram was evaluated. Specifically, a polyester plain fabric belt conveyor 3 with a conveyor length of 30cm, a width of 30cm, and a curvature radius of 0.5cm was used. A test piece 1 was placed on the belt conveyor 3, and a plastic conveying component 2 with a bottom surface of 150mm and a mass of 260g was adsorbed onto the belt conveyor 3. At an air velocity of 5.0m / min, suction was applied to the inside of the belt conveyor 3 by a suction mechanism (not shown). Figure 1 The right-side delivery mechanism 4 moves to the left to transport the conveying component 2. Furthermore, the coefficient of dynamic friction between the conveying component 2 and the test piece 1 is 0.35, and the operation of transporting 50 pieces is repeated 5 times at a conveying speed of 1 piece per second.

[0164] (8-2) Whether there is sheet loosening

[0165] After the transfer operation, check whether there is any loose sheet material at both ends of the process protective material.

[0166] (8-3) Suction and fixing of conveying components

[0167] After the transfer operation, check whether the transfer components have shifted in the width direction, and check whether there are any transfer components with a shift of more than 1cm.

[0168] (8-4) Hairiness

[0169] Before and after handling, the surface of the long-fiber nonwoven fabric was visually observed at three points on each roll, and then observed using a scanning electron microscope (SEM, KEYENCE VHX-950H). Cases where no change in surface condition was observed before and after handling were marked with "5"; cases where the surface was unclear to the naked eye but showed slight fuzzing under SEM were marked with "4"; cases where the surface was unclear to the naked eye but showed significant fuzzing under SEM were marked with "3"; cases where fuzzing was visible to the naked eye were marked with "2"; and cases where the sheet shape could not be maintained were marked with "1".

[0170] [Resin used]

[0171] Next, details of the resins used in the examples and comparative examples will be described.

[0172] • High melting point polymer: Polyethylene terephthalate (labeled as PET in Tables 1 and 2) dried to a moisture content of less than 50 ppm by mass, with an intrinsic viscosity (IV) of 0.65 and a melting point of 260°C.

[0173] • Low melting point polymer: copolymerized polyethylene terephthalate (labeled as co-PET in Tables 1 and 2) with a moisture content of less than 50 ppm by mass, an intrinsic viscosity (IV) of 0.64, a copolymerization rate of 11 mol% of isophthalic acid, and a melting point of 230 °C.

[0174] [Example 1]

[0175] (Process for obtaining long fibers)

[0176] The high-melting-point polymer and the low-melting-point polymer are melted at temperatures of 295°C and 280°C, respectively. Then, with the high-melting-point polymer as the core component and the low-melting-point polymer as the sheath component, the polymer is spun out from the nozzle of a circular spinneret at a core-to-sheath mass ratio of 80:20, under the condition of a die temperature of 295°C.

[0177] Then, the spun thermoplastic resin is pulled and stretched using an ejector at a spinning speed of 4900 m / min to form long fibers with a circular cross-section.

[0178] (The process of forming a fiber web)

[0179] For the long fibers, after restricting their arrangement using a fiber opener, they are collected onto a moving mesh belt conveyor to form a composite fiber containing an average single fiber diameter of 12.3 μm and a unit area weight of 50 g / m². 2 Fiber web.

[0180] (The process of obtaining preheated fiber web)

[0181] The fiber web formed is transported by a mesh belt conveyor, and a heating plate (made of metal, with a heating surface temperature of 155°C) located above the mesh belt conveyor contacts the surface of the fiber web that is not in contact with the mesh belt conveyor with a linear pressure of 10 N / cm. This preheats only one surface of the fiber web, thus obtaining a preheated fiber web.

[0182] (Thermal bonding process)

[0183] The preheated fiber web was passed through a pair of metal flat rollers, including two flat rollers with a surface temperature of 185°C and a linear pressure of 700 N / cm, for thermal bonding to obtain a long-fiber nonwoven fabric. The results are shown in Table 1.

[0184] The apparent density of this long-fiber nonwoven fabric is 0.58 g / cm³. 3 Ventilation volume is 25cm 3 / (cm 2 • seconds), surface roughness R of each surface z The diameters are 35.8 μm and 43.4 μm, and the area ratio of the fiber voids is 5.0%.

[0185] The result of using this long-fiber nonwoven fabric as a process protection material is that there is no loosening of the sheet, there are no problems with the suction and fixation of the conveying components, and the fuzziness is 5.

[0186] [Example 2]

[0187] In the process of obtaining the preheated fiber web, a metal heating plate was used for preheating, and the linear pressure was 10 N / cm. Except that a metal flat roller was used to change the linear pressure to 50 N / cm, the same method as in Example 1 was used. The results are shown in Table 1.

[0188] The obtained long-fiber nonwoven fabric has a unit area weight of 50 g / m². 2 The apparent density is 0.61 g / cm³. 3 Ventilation volume is 18cm 3 / (cm 2 • seconds), surface roughness R of each surface z The diameters are 36.2 μm and 43.6 μm, and the area ratio of the fiber voids is 10.0%.

[0189] The result of using this long-fiber nonwoven fabric as a process protection material is that there is no loosening of the sheet, there are no problems with the suction and fixation of the conveying components, and the fuzziness is 5.

[0190] [Example 3]

[0191] In the process of forming the fiber web, the speed of the moving mesh belt conveyor is adjusted to achieve a unit area weight of 50 g / m². 2 The long-fiber nonwoven fabric, in addition to being adjusted to obtain a unit area weight of 70g / m², 2 Except for the long-fiber nonwoven fabric, the same method as in Example 2 was used. The results are shown in Table 1.

[0192] The apparent density of the obtained long-fiber nonwoven fabric is 0.59 g / cm³. 3 Ventilation volume is 7cm 3 /

[0193] (cm 2 • seconds), surface roughness R of each surface z The diameters are 32.1 μm and 39.8 μm, and the area ratio of the fiber voids is 0.2%.

[0194] The result of using this long-fiber nonwoven fabric as a process protection material is that there is no loosening of the sheet, there are no problems with the suction and fixation of the conveying components, and the fuzziness is 5.

[0195] [Table 1]

[0196]

[0197] [Comparative Example 1]

[0198] In the process of obtaining the preheated fiber web, the heating plate is removed without preheating (i.e., the fiber web is directly transported using a moving mesh belt conveyor). In the process of thermal bonding, the fiber web is thermally bonded by passing it through a pair of metal flat rollers, including two flat rollers with a surface temperature of 195°C and a linear pressure of 700 N / cm. Otherwise, the process is carried out using the same method as in Example 1. The results are shown in Table 2.

[0199] The obtained long-fiber nonwoven fabric has a unit area weight of 50 g / m². 2 The apparent density is 0.81 g / cm³. 3 Ventilation volume is 7cm 3 / (cm 2 • seconds), surface roughness R of each surface z The diameters are 32.3 μm and 32.9 μm, and the area ratio of the fiber voids is 0.1%.

[0200] Using this long-fiber nonwoven fabric as a process protection material resulted in no problems with the suction and fixation of the conveying components, and the fuzziness was 5, but sheet loosening occurred.

[0201] [Comparative Example 2]

[0202] In the process of obtaining the preheated fiber web, the heating plate is removed without preheating (i.e., the fiber web is directly transported using a moving mesh belt conveyor). In the process of thermal bonding, the fiber web is passed through a pair of metal flat rollers with a surface temperature of 150°C and a linear pressure of 700 N / cm, and then through another pair of metal flat rollers with a surface temperature of 195°C and a linear pressure of 700 N / cm, thereby performing a two-stage thermal bonding. Otherwise, the process is carried out using the same method as in Example 1. The results are shown in Table 2.

[0203] The obtained long-fiber nonwoven fabric has a unit area weight of 50 g / m². 2 The apparent density is 0.57 g / cm³. 3 Ventilation volume is 22cm 3 / (cm 2 • seconds), surface roughness R of each surface z The diameters are 36.2 μm and 37.1 μm, and the area ratio of the fiber voids is 2.1%.

[0204] Using this long-fiber nonwoven fabric as a process protection material resulted in no problems with the suction and fixation of the conveying components, and the fuzziness was 5, but sheet loosening occurred.

[0205] [Comparative Example 3]

[0206] (Process for obtaining long fibers)

[0207] The high-melting-point polymer and the low-melting-point polymer are melted at temperatures of 295°C and 280°C, respectively. Then, with the high-melting-point polymer as the core component and the low-melting-point polymer as the sheath component, the polymer is spun out from the nozzle of a circular spinneret at a core-to-sheath mass ratio of 80:20, under the condition of a die temperature of 295°C.

[0208] Then, the spun thermoplastic resin is pulled and stretched using an ejector at a spinning speed of 4900 m / min to form long fibers with a circular cross-section.

[0209] (The process of forming a fiber web)

[0210] The long fibers are constrained by a fiber opener and then collected onto a moving mesh belt conveyor to form a composite fiber containing an average single fiber diameter of 11.4 μm and a unit area weight of 35 g / m². 2 Fiber web.

[0211] (The process of obtaining preheated fiber web)

[0212] The fiber web formed is transported by a mesh belt conveyor, and a heating plate (made of metal, with a heating surface temperature of 135°C) located above the mesh belt conveyor contacts the surface of the fiber web that is not in contact with the mesh belt conveyor with a linear pressure of 10 N / cm. This preheats only one surface of the fiber web, thus obtaining a preheated fiber web.

[0213] (Thermal bonding process)

[0214] The preheated fiber web is thermally bonded by passing it through a pair of metal flat rollers (two flat rollers with a surface temperature of 135°C and a linear pressure of 490 N / cm) to obtain a nonwoven sheet. Then, the obtained nonwoven sheet is overlapped twice and passed through three sections of flat rollers (upper, middle, and lower) in the order of middle-to-lower section rollers and middle-to-upper section rollers for further thermal bonding. Finally, it is brought into contact with a metal cooling roller with a surface temperature of 45°C for one second to obtain a long-fiber nonwoven fabric. The details of the three sections of flat rollers are as follows.

[0215] The upper section flat roller is a resin-made elastic roller with a hardness (Shore D) of 91 and an average surface roughness Ra of 4 μm (surface temperature: 130℃).

[0216] The middle section flat roller: metal roller (surface temperature: 195℃)

[0217] The lower section's flat roller: a resin-made elastic roller with a hardness (Shore D) of 91 and an average surface roughness Ra of 4 μm (surface temperature: 130℃).

[0218] Linear pressure between the upper and middle flat rollers: 1850 N / cm

[0219] Linear pressure between the middle section flat roller and the lower section flat roller: 1850 N / cm

[0220] The results are shown in Table 2.

[0221] The result of using this long-fiber nonwoven fabric as a process protection material is that although there is no sheet loosening and the fuzziness is 5, the suction and fixation of the conveying components is weak, resulting in the displacement of the conveying components.

[0222] The obtained long-fiber nonwoven fabric has a unit area weight of 70 g / m². 2 The apparent density is 0.83 g / cm³. 3 Ventilation volume is 1 cm 3 / (cm 2 • seconds), surface roughness R of each surface z The diameters are 24.8 μm and 30.0 μm, and the area ratio of the fiber voids is 0.1%.

[0223] [Comparative Example 4]

[0224] A blended fiber web was made by combining 30 parts by weight of drawn filaments containing the high-melting-point polymer (average single fiber diameter 17.0 μm, fiber length 64 mm), 20 parts by weight of drawn filaments containing the high-melting-point polymer (average single fiber diameter 10.0 μm, fiber length 38 mm), and 50 parts by weight of undrawn filaments containing the high-melting-point polymer (average single fiber diameter 22.0 μm, fiber length 38 mm). The blended fiber web was then passed through a pair of metal flat rollers (two flat rollers with a surface temperature of 180°C and a linear pressure of 600 N / cm) to thermally bond the entire surface of the blended fiber web, resulting in a weight per unit area of ​​63 g / m². 2 The short-fiber nonwoven fabric. The results are shown in Table 2.

[0225] The apparent density of the obtained short-fiber nonwoven fabric is 0.60 g / cm³. 3 Ventilation volume is 8cm 3 /

[0226] (cm 2 • seconds), surface roughness R of each surface z The diameters are 40.8 μm and 44.6 μm, and the area ratio of the fiber voids is 0.4%.

[0227] The result of using this short fiber nonwoven fabric as a process protection material is that although there is no sheet loosening and the suction and fixation of the conveying components are not a problem, the fuzziness is 2.

[0228] [Comparative Example 5]

[0229] In the process of obtaining the preheated fiber web, a metal heating plate was used for preheating, and the linear pressure was 10 N / cm. Except that a metal flat roller was used, the temperature of the heating surface was changed to 205°C, and the linear pressure was changed to 50 N / cm, the same method as in Example 1 was used. The results are shown in Table 2.

[0230] The obtained long-fiber nonwoven fabric has a unit area weight of 50 g / m². 2 The apparent density is 0.45 g / cm³. 3 Ventilation volume is 32cm 3 / (cm 2 • seconds), surface roughness R of each surface z The diameters are 24.1 μm and 40.2 μm, and the area ratio of the fiber voids is 16.3%.

[0231] The result of using this long-fiber nonwoven fabric as a process protection material is that although the napping property is 5, there is sheet loosening. The suction and fixation of the conveying components are also too strong, which causes the conveying components to deform.

[0232] [Table 2]

[0233]

[0234] <Summary>

[0235] As described above, the results of using the long-fiber nonwoven fabrics obtained in the Examples and Comparative Examples as process protection materials confirmed that in the long-fiber nonwoven fabrics of Examples 1 to 3, there was no sheet loosening, the suction and fixation of the conveying components were not problematic, the fuzzing properties were good, and the abrasion resistance was excellent. On the other hand, in the long-fiber nonwoven fabrics of Comparative Examples 1 and 2, there was no surface-back difference, the sheet ends were prone to curling and loosening, and some sheet loosening occurred. In addition, in the long-fiber nonwoven fabric of Comparative Example 3, due to its high density and smooth surface, the conveying components could not be adequately suctioned and fixed during conveying, resulting in poor conveyability. Furthermore, for the short-fiber nonwoven fabric of Comparative Example 4, although there were no problems with conveyability, after two identical processing steps, the surface observation using SEM showed fuzzing, and after a total of five identical processing steps, fuzzing was still observed visually, resulting in poor continuous production. Furthermore, in the long-fiber nonwoven fabric of Comparative Example 5, the temperature increased during the preheating process, resulting in a greater difference in surface roughness of the long-fiber nonwoven fabric. This caused the sheet to curl and loosen during transport. In addition, due to the high temperature on the preheated side, crystallization occurred, leading to a decrease in adhesion during thermal bonding and an increase in air permeability. As a result, the suction situation became stronger, as described above, causing deformation of the transport component.

[0236] Based on the results, the long-fiber nonwoven fabric of the present invention is a long-fiber nonwoven fabric with excellent followability to conveyors, excellent transportability and abrasion resistance, and can withstand continuous use.

[0237] Although the present invention has been described in detail with reference to a specific form, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

Claims

1. A long fiber nonwoven fabric that is a long fiber nonwoven fabric composed of a fiber in which a thermoplastic resin is a main component, the thermoplastic resin being polyethylene terephthalate, a polyethylene terephthalate mixture, or a polyethylene terephthalate copolymer, the proportion of the mass of the thermoplastic resin with respect to the mass of the entire fiber being more than 50 mass%, wherein, The surface roughness R z of both sides of the long fiber nonwoven fabric is 25.0 μm or more and 50.0 μm or less z The absolute value of the difference between the surface roughness R z of one side and the surface roughness R of the other side is 4.0 μm or more and 10.0 μm or less.

2. The long fiber nonwoven fabric according to claim 1, wherein The area ratio of the fiber gap portion of the long fiber nonwoven fabric is 1.0% or more and 15.0% or less.

3. The long fiber nonwoven fabric according to claim 1 or 2, wherein The fiber is a composite fiber in which a low-melting-point polymer is provided around a high-melting-point polymer, the low-melting-point polymer having a melting point lower than the melting point of the high-melting-point polymer.

4. The long fiber nonwoven fabric according to claim 1 or 2, wherein The apparent density of the long fiber nonwoven fabric is 0.40 g / cm 3 The apparent density of the long fiber nonwoven fabric is 0.40 g / cm 3 The apparent density of the long fiber nonwoven fabric is 0.40 g / cm 5. The long fiber nonwoven fabric according to claim 1 or 2, wherein The long fiber nonwoven fabric has a weight per unit area of 40 g / m 2 The above and 75 g / m 2 The following.

6. A method of manufacturing a long fiber nonwoven fabric according to claim 1 or 2, comprising, in this order: a step of spinning the thermoplastic resin from a spinning hole of a spinneret, further performing suction stretch, thereby obtaining long fibers; a step of capturing the long fibers onto a moving web belt conveyor, thereby forming a fiber web; a step of preheating the fiber web by bringing a heating surface into contact with only one surface of the fiber web, thereby obtaining a preheated fiber web; and a step of heat-bonding the preheated fiber web using a pair of flat rolls, the spinning speed in the suction stretch is 3,000 m / min or more and 6,000 m / min or less, in the preheating, the temperature of the heating surface is a temperature of 30°C or more and 110°C or less lower than the melting point of the thermoplastic resin, and the linear pressure of the heating surface is 1 N / cm or more and 100 N / cm or less, in the heat-bonding, the surface temperature of the pair of flat rolls is a temperature of 30°C or more and 70°C or less lower than the melting point of the thermoplastic resin, and the linear pressure of the pair of flat rolls is 100 N / cm or more and 900 N / cm or less.

7. A method of manufacturing a long fiber nonwoven fabric according to claim 3, comprising, in this order: a step of spinning a high-melting-point polymer and a low-melting-point polymer having a melting point of 10°C or more and 110°C or less lower than the melting point of the high-melting-point polymer from a spinning hole of a composite spinneret, further performing suction stretch, thereby obtaining a composite fiber in which the low-melting-point polymer is provided around the high-melting-point polymer, i.e., a long fiber; a step of capturing the long fibers onto a moving web belt conveyor, thereby forming a fiber web; a step of preheating the fiber web by bringing a heating surface into contact with only one surface of the fiber web, thereby obtaining a preheated fiber web; and a step of heat-bonding the preheated fiber web using a pair of flat rolls, the spinning speed in the suction stretch is 3,000 m / min or more and 6,000 m / min or less, in the preheating, the temperature of the heating surface is a temperature of 30°C or more and 110°C or less lower than the melting point of the low-melting-point polymer, and the linear pressure of the heating surface is 1 N / cm or more and 100 N / cm or less, in the heat-bonding, the surface temperature of the pair of flat rolls is a temperature of 30°C or more and 70°C or less lower than the melting point of the low-melting-point polymer, and the linear pressure of the pair of flat rolls is 100 N / cm or more and 900 N / cm or less.

8. A process protection material comprising the long fiber nonwoven fabric according to claim 1 or 2.

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