Polyester-based filament nonwoven fabric

Abstract

To obtain a polyester-based filament nonwoven fabric for which formability can be improved further than a case of using copolyester, without using copolyester in which a third component is copolymerized in polyester such as polyethylene terephthalate.SOLUTION: A nonwoven fabric is a polyester-based filament nonwoven fabric constituted of a core-sheath type conjugate fiber in which polyester-based polymer A is provided in a core part, and polyester-based polymer B is provided in a sheath part. The sheath part contains the polyester-based copolymer B as well as copolyester in which terephthalic acid, as acid component, and tetramethylcyclobutanediol and cyclohexane dimethanol, as glycol components, are copolymerized.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester long-fiber nonwoven fabric, and more particularly to a polyester long-fiber nonwoven fabric suitable for molding applications. [Background technology]

[0002] Polyester long-fiber nonwoven fabrics are used in a variety of fields due to their high strength and excellent durability. Among them, molded products made from the nonwoven fabric alone or composites with other materials into a specific shape take advantage of the properties of continuous fiber nonwoven fabrics.

[0003] An example of a polyester-based long-fiber nonwoven fabric suitable for such molding applications is given in Patent Document 1. Patent Document 1 proposes using a combination of an aromatic polyester and a low-melting point copolymer polyester as the polyester, which is the constituent polymer of the nonwoven fabric. That is, the continuous fibers constituting the long-fiber nonwoven fabric used for molding are a combination of an aromatic polyester and an aromatic copolymer polyester. Specific combination methods include conjugated spinning of two polyesters to form a core-sheath composite fiber or a side-by-side fiber, blend spinning of two polyesters to form a blend fiber, and blending a low-melting point thermal adhesive fiber with a high-melting point fiber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-62084 A, paragraph number 0015 Summary of the Invention [Problem to be solved by the invention]

[0005] However, copolymerized polyesters obtained by copolymerizing a third component with a polyester such as polyethylene terephthalate have a low melting point and therefore have poor dimensional stability at high temperatures, resulting in problems such as poor thermoformability at high temperatures and poor heat resistance.

[0006] Therefore, an object of the present invention is to obtain a polyester-based long-fiber nonwoven fabric that can improve moldability compared to when a copolymer polyester is used, without using a copolymer polyester in which a third component is copolymerized with polyethylene terephthalate. [Means for solving the problem]

[0007] To achieve this object, the polyester long-fiber nonwoven fabric of the present invention is characterized in that it comprises core-sheath composite fibers in which a polyester polymer A is disposed in the core and a polyester polymer B is disposed in the sheath, and the sheath contains, in addition to the polyester polymer B, a copolymer polyester obtained by copolymerizing terephthalic acid as an acid component with tetramethylcyclobutanediol and cyclohexanedimethanol as glycol components.

[0008] According to the polyester long-fiber nonwoven fabric of the present invention, it is preferable that the polymer constituting the sheath contains 1.0 to 10% by mass of a copolymer polyester.

[0009] According to the polyester long fiber nonwoven fabric of the present invention, it is preferable that the melting point of the polyester polymer A is 240 to 270°C.

[0010] In the polyester long-fiber nonwoven fabric of the present invention, it is preferable that both the polyester polymer A and the polyester polymer B are polyethylene terephthalate.

[0011] In the polyester long-fiber nonwoven fabric of the present invention, the mass ratio of the core to the sheath is preferably (sheath) / (core)=10 / 90 to 50 / 50.

[0012] The method for producing a polyester long-fiber nonwoven fabric of the present invention is characterized in that the drawing speed when obtaining the constituent fibers for the polyester long-fiber nonwoven fabric is 3000 to 4500 m / min. [Effects of the Invention]

[0013] According to the present invention, the sheath portion is composed of polyester polymer B and copolymer polyester, and this copolymer polyester is a copolymer of terephthalic acid as the acid component and tetramethylcyclobutanediol and cyclohexanedimethanol as glycol components. Therefore, although the reason is not clear, it is possible to obtain an excellent molding nonwoven fabric that is easily stretched when pulled and is resistant to fracture or breakage. DETAILED DESCRIPTION OF THE INVENTION

[0014] In the constituent fibers of the polyester long-fiber nonwoven fabric of the present invention, the polyester polymer A of the core and the polyester polymer B of the sheath can be the same. As such a polyester polymer, conventionally known polyesters such as aromatic polyesters and aliphatic polyesters can be used. Polyethylene terephthalate is particularly suitable for use because it has good heat resistance and excellent mechanical strength.

[0015] The sheath must contain, in addition to polyester polymer B, a copolymerized polyester obtained by copolymerizing terephthalic acid (TPA) as an acid component with tetramethylcyclobutanediol (TMCD) and cyclohexanedimethanol (CHDM) as glycol components. The content of this copolymerized polyester in the polymer constituting the sheath is preferably 1.0 to 10 mass%. By configuring the polymer constituting the sheath in this way, an excellent nonwoven fabric for molding can be obtained that is easily stretched when pulled and is resistant to breakage or rupture.

[0016] The reason for this is unclear, but it can be considered as follows. In the present invention, the sheath contains a copolymerized polyester obtained by copolymerizing terephthalic acid (TPA) as the acid component with tetramethylcyclobutanediol (TMCD) and cyclohexanedimethanol (CHDM) as the glycol components. This copolymerized polyester does not exhibit crystallinity, is amorphous, has no melting point, and has excellent extensibility. In producing a continuous-fiber nonwoven fabric, when the polymers contained in the core and sheath are melt-spun and then taken up at high speed, the polyester polymer A and polyester polymer B contained in the core and sheath undergo molecular orientation and crystallize. However, the copolymerized polyester of TPA, TMCD, and CHDM contained in the sheath is amorphous and does not crystallize. Since the sheath contains the amorphous copolymerized polyester of TPA, TMCD, and CHDM, it is thought that the polyester polymer B in the sheath is less likely to crystallize than the polyester polymer A in the core. Therefore, by combining polymers of this configuration and taking them up at high speed after melt spinning, oriented crystallization of the core is promoted, while the sheath is composed of the amorphous copolyester and polyester polymer B, in which oriented crystallization is suppressed. Therefore, the sheath functions well as a thermal adhesive component for forming a nonwoven fabric. That is, the sheath softens well at temperatures lower than the melting point of polyester polymer B, resulting in excellent thermal adhesiveness. Furthermore, since the polyester long-fiber nonwoven fabric of the present invention can be thermally bonded at temperatures lower than the melting point of polyester polymer B (temperatures approximately 100°C lower than the melting point of the polyester polymer), and the sheath contains an amorphous copolyester, it is easily stretched when pulled and is less likely to break or fracture, which is thought to result in good conformability during molding.

[0017] In order for the sheath to function well as a thermal adhesive component for forming a nonwoven fabric as described above, the glass transition temperature of the copolymer polyester contained in the sheath is preferably 90°C to 120°C, more preferably 100°C to 120°C, and even more preferably 110°C to 120°C.

[0018] The content of the copolymer polyester in the polymer constituting the sheath is preferably 1.0 to 10% by mass in order to exert the above-mentioned functions.

[0019] As the copolymer polyester, commercially available products can be suitably used, such as "Tritan (registered trademark)" sold by Nagase & Co., Ltd.

[0020] The polyester polymer A of the core has a melting point of 240 to 270°C, which can contribute to heat resistance for thermoforming.

[0021] In the polyester long-fiber nonwoven fabric of the present invention, the sheath functions as a thermal adhesive component for forming the nonwoven fabric, and the core functions as a fiber-constituting component for forming the nonwoven fabric. To ensure that both functions are satisfactorily exerted, it is preferable that the mass ratio of the core to the sheath is (sheath) / (core) = 10 / 90 to 50 / 50.

[0022] The single fiber fineness of the constituent fibers of the nonwoven fabric may be appropriately selected depending on the application of the nonwoven fabric, and is not particularly limited, but is generally about 0.5 to 12 decitex (dtex).

[0023] The basis weight of the nonwoven fabric may be selected appropriately depending on the application, but is generally 10 to 200 g / m 2 Good condition. Weight is 10g / m 2 If the weight is less than 200 g / m, the fabric may have poor texture and mechanical strength, making it impractical. 2 If the weight exceeds this, it may be disadvantageous in terms of cost. Considering thermoformability, the weight should be 10 to 80 g / m 2 is good.

[0024] Next, a preferred method for producing the nonwoven fabric of the present invention will be described.

[0025] The nonwoven fabric of the present invention can be efficiently produced by the spunbonding method. First, chips of polyester polymer A for the core portion described above, and chips of the copolymer polyester and polyester polymer B for the sheath portion are prepared. Then, both are melt-metered separately, and melt-spun using a core-sheath bicomponent spinneret, with polyester polymer A supplied to the nozzle hole forming the core portion and a predetermined amount of copolymer polyester and polyester polymer B supplied to the nozzle hole forming the sheath portion. The spun yarn spun from the spinneret is cooled using a conventionally known cooling device such as a horizontal or annular blower, and then pulled and thinned using a suction device.

[0026] The drawing speed during drawing and thinning is set to 3000 to 4500 m / min. If the drawing speed is less than 3000 m / min, molecular orientation is not sufficiently promoted in the yarn, and the dimensional stability of the resulting nonwoven fabric tends to be poor. On the other hand, if the drawing speed exceeds 4500 m / min, a large stress is applied to the yarn, and crystallization of the sheath polymer also progresses, making it difficult to obtain the nonwoven fabric intended by the present invention.

[0027] The drawn and attenuated core-sheath composite fibers are opened using a known opening device, and then opened and deposited on a moving collecting surface such as a screen conveyor to form a nonwoven web. This nonwoven web is then partially thermocompressed using a thermocompression bonding device such as a thermal embossing device to integrate the constituent fibers, thereby obtaining the nonwoven fabric of the present invention.

[0028] The heat treatment temperature (roll setting temperature of the hot embossing device) during partial heating and pressurization is preferably set to 100°C or higher and 200°C or lower. As described above, the core-sheath composite fiber of the present invention can have the same polyester polymer in both the core and sheath. However, the polymer constituting the sheath contains a copolymerized polyester obtained by copolymerizing terephthalic acid (TPA) as the acid component with tetramethylcyclobutanediol (TMCD) and cyclohexanedimethanol (CHDM) as glycol components. This copolymerized polyester is amorphous. This amorphous copolymerized polyester contributes to adhesiveness and moldability. Furthermore, the presence or absence of this copolymerized polyester results in differences in the ease of crystal orientation between the core and sheath. It is believed that when such polymers are combined and taken up at high speed after melt spinning, oriented crystallization is promoted in the core but suppressed in the sheath. [Example]

[0029] Various physical properties in the following examples and comparative examples were evaluated as follows.

[0030] Glass transition temperature of polyester resin [Tg]: Measurements were performed using a power compensation differential scanning calorimeter (Diamond DSC model manufactured by PerkinElmer) in accordance with JIS-K 7121, at a temperature rise rate of 10°C / min from -60°C to 120°C. The temperature at the intersection of a straight line extending the low-temperature baseline toward the high-temperature side in the obtained temperature rise curve and a tangent drawn at the point where the gradient of the curve in the stepwise change portion of the glass transition is maximum was determined, and this intersection was taken as the glass transition temperature.

[0031] Intrinsic viscosity of polyester resin [dL / g]: The measurement was carried out in accordance with a conventional method using a mixture of equal masses of phenol and tetrachloroethane as a solvent at a temperature of 20°C.

[0032] Weight [g / m 2 ]: Ten 10 cm x 10 cm test pieces were cut from the obtained nonwoven fabric. Each test piece was weighed under standard conditions (20°C, 65% RH), and the average value of the weights was calculated. This average value was converted into mass per unit area to determine the basis weight (g / m) of the nonwoven fabric. 2 ) was decided.

[0033] Fineness [dtex]: From the deposited web, 50 constituent fibers were randomly extracted and their fiber diameters were measured under a microscope. These measurements were corrected for density to calculate the fineness of each fiber, and the average value was calculated to determine the fineness.

[0034] 5% stronger [N / 5cm]: The stress at 5% elongation when measured under the same conditions as the tensile strength below was defined as the 5% strength.

[0035] Tensile strength [N / 5cm]: Ten specimens, each 20 cm long and 5 cm wide, were prepared. Each specimen was stretched at a grip distance of 10 cm and a tensile speed of 20 cm / min using a constant-rate extension tensile tester (Orientec Co., Ltd., "Tensilon UTM-4-1-100") to measure the breaking load (N / 5 cm) at break. The average value of the breaking load was taken as the tensile strength. Measurements were performed in the machine direction (MD) and the direction crossing the machine direction (CD).

[0036] Breaking elongation [%]: The tensile strength was calculated using the following formula, where the length of the sample piece before evaluation was L0 and the length of the sample piece at the time of cutting was L. (Breaking elongation) (%) = {(L-L0) / L0} × 100

[0037] Tear strength [N]: Measurement was performed based on the pendulum method of JIS L1913. The measurement direction was the machine direction (MD), which is the direction in which tear strength is low.

[0038] Fluff [grade]: The nonwoven fabric was placed in a Gakushin-type abrasion fastness tester with the ER side in contact with the ER side under a load of 200 g and subjected to 75 abrasion cycles. After that, the samples were visually evaluated. The number of samples was set to 5. Evaluation was based on the following criteria. Grade 5: No fluffing or pilling Grade 4: A little fluff, no pilling Grade 3: Only small pills (10mm or less) occur Grade 2: Two or fewer hairballs (10mm or larger) occur Grade 1: 3 or more large hairballs

[0039] 200℃×5min dry heat shrinkage rate [%]: Five 15cm x 15cm test pieces were prepared. Each test piece was left at 180°C for 5 minutes, and the shrinkage was calculated using the following formula. The average of the calculated values ​​was taken as the dry heat shrinkage. (Shrinkage rate) (%) = [(15-Lx) / 15] x 100 In the above formula, Lx represents the length of the sample after being left for 5 minutes.

[0040] Moldability: The obtained nonwoven fabric was preheated at 200°C for 1 minute, the periphery of which was fixed, and a mold with a rectangular pillar-shaped protrusion (approximately 50 mm long, 50 mm wide, and 20 mm high) was pressed against it to thermoform it. The molded product was visually observed and evaluated according to the following criteria. ⊚: The molding was excellent, the four corners of the square pillar were perfectly rounded, and there were no wrinkles. Good: The molding was mostly successful, but it was not possible to completely follow the curves of the four corners of the square prism. ×: The film could not be made to fit the rectangular pillar, and tears or the like occurred.

[0041] Example 1 The polyester polymer used was polyethylene terephthalate with a melting point of 258°C and an intrinsic viscosity of 0.65 dL / g. This polyester polymer was individually weighed to a sheath / core ratio of 30 / 70 (mass ratio), then melted using individual extruder-type extruders and melt-spun to obtain a core-sheath composite cross section. The sheath contained 5.0 mass% of a copolymer polyester (Eastman's "Tritan TX1001") with a glass transition temperature of 110°C and a specific gravity of 1.18, which was copolymerized with terephthalic acid (TPA) as the acid component and tetramethylcyclobutanediol (TMCD) and cyclohexanedimethanol (CHDM) as the glycol components.

[0042] The spun yarn was cooled in a known cooling device, then pulled and thinned by an air sucker installed below the spinneret at a pulling speed of 4000 m / min, and then spread using a known fiber spreader. The yarn was then collected and deposited as a web on a moving screen conveyor. The single fiber fineness of the deposited conjugated continuous fiber was 3.1 dtex.

[0043] Next, the web was passed through a heat embossing device consisting of an embossing roll and a smooth-surfaced metal roll to be heat-treated, and the weight of the web was reduced to 15 g / m 2 The heat embossing conditions were a surface temperature of 140°C for both rolls. 2 The hexagonal engraved pattern has a pressure contact density of 20 points / cm 2 The pressure contact area ratio was 15%.

[0044] The physical properties of the obtained polyester long fiber nonwoven fabric are shown in Table 1.

[0045] [Table 1]

[0046] Example 2 Under the same conditions as in Example 1, the basis weight was 20 g / m 2The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0047] Example 3 Under the same conditions as in Example 1, the basis weight was 30 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0048] Example 4 Under the same conditions as in Example 1, the basis weight was 40 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0049] Example 5 Under the same conditions as in Example 1, the basis weight was 50 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0050] Example 6 Under the same conditions as in Example 1, the basis weight was 70 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0051] Example 7 Compared with Example 1, the sheath / core mass ratio in the conjugated continuous fiber was changed to 25 / 75. Other conditions were the same as in Example 1, and the basis weight was 15 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0052] Example 8 Under the same conditions as in Example 7, the basis weight was 20 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0053] Example 9 Under the same conditions as in Example 7, the basis weight was 30 g / m 2The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0054] Example 10 Under the same conditions as in Example 7, the basis weight was 40 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0055] Example 11 Under the same conditions as in Example 7, the basis weight was 50 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0056] Example 12 Under the same conditions as in Example 7, the basis weight was 70 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0057] Comparative Example 1 As the first polyester polymer, polyethylene terephthalate with a melting point of 258°C and an intrinsic viscosity of 0.65 dL / g was prepared. As the second polyester polymer, the following was prepared. That is, 92 mol% of terephthalic acid (TPA) and 8 mol% of isophthalic acid (IPA) were used as the dicarboxylic acid component, and 100 mol% of ethylene glycol (EG) was used as the diol component to copolymerize them, resulting in a low-melting point polyester (intrinsic viscosity 0.79 dL / g, melting point 230°C). Each polyester polymer was weighed individually (mass ratio of the first polyester polymer to the second polyester polymer = 7:3), melted using individual extruder-type extruders, and melt-spun to form a mixed fiber with a round cross section.

[0058] The spun yarn was cooled in a known cooling device, then pulled and thinned by an air sucker installed below the spinneret at a pulling speed of 5000 m / min, and then spread using a known fiber spreader. The yarn was then collected and deposited as a web on a moving screen conveyor. The single fiber fineness of the deposited mixed continuous fibers was 3.0 dtex for the first polyester polymer and 2.5 dtex for the second polyester polymer.

[0059] Next, the web was passed through a heat embossing device consisting of an embossing roll and a smooth-surfaced metal roll to be heat-treated, and the weight of the web was reduced to 25 g / m 2 The heat embossing conditions were a surface temperature of 210°C for both rolls. 2 The hexagonal engraved pattern has a pressure contact density of 20 points / cm 2 The pressure contact area ratio was 15%.

[0060] The physical properties of the obtained polyester long fiber nonwoven fabric are shown in Table 1.

[0061] Comparative Example 2 Under the same conditions as in Comparative Example 1, the basis weight was 30 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0062] Comparative Example 3 Under the same conditions as in Comparative Example 1, the basis weight was 50 g / m 2 The physical properties of the obtained polyester long-fiber nonwoven fabric are shown in Table 1.

[0063] The nonwoven fabrics of Examples 1 to 12 had high elongation under low load compared to the nonwoven fabrics of Comparative Examples 1 to 3, and showed excellent moldability.

[0064] Regarding moldability, when a mold with convex portions was pressed against the sample to perform thermoforming, all of the nonwoven fabrics of Examples 1 to 12 conformed well to the convex portions (approximately 2 cm in height) of the mold, and were able to be molded well, particularly to the corners of the convex portions, which had a square cross-sectional shape.

[0065] On the other hand, the nonwoven fabrics of Comparative Examples 1 to 3 were unable to follow the corners of the convex parts of the mold, and the nonwoven fabrics were partially pulled by the convex parts.

Claims

1. A polyester long-fiber nonwoven fabric comprising core-sheath composite fibers in which a polyester polymer A is disposed in the core and a polyester polymer B is disposed in the sheath, and the sheath contains, in addition to the polyester polymer B, a copolymerized polyester obtained by copolymerizing terephthalic acid as an acid component and tetramethylcyclobutanediol and cyclohexanedimethanol as glycol components.

2. 2. The polyester long-fiber nonwoven fabric according to claim 1, wherein the polymer constituting the sheath contains 1.0 to 10% by mass of a copolymer polyester.

3. 3. The polyester long-fiber nonwoven fabric according to claim 1, wherein the polyester polymer A has a melting point of 240 to 270°C.

4. 3. The polyester long-fiber nonwoven fabric according to claim 1, wherein both the polyester polymer A and the polyester polymer B are polyethylene terephthalate.

5. 3. The polyester long-fiber nonwoven fabric according to claim 1, wherein the mass ratio of the core to the sheath is (sheath) / (core)=10 / 90 to 50 / 50.

6. A method for producing a polyester-based long-fiber nonwoven fabric according to claim 1 or 2, characterized in that the pulling speed when obtaining constituent fibers for the long-fiber nonwoven fabric is 3,000 to 4,500 m / min.

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