JP2013136851A - Polyester-based conjugate binder fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder fiber that can be used to make paper having a high paper strength and is suppressed in a sticking problem in order to solve such a problem of a polyester binder fiber that can be used to make paper having a high paper strength that a sticking trouble to a roller during a process frequently occurs due to the binder performance in exchange for an improved paper strength.SOLUTION: There is provided an undrawn polyester-based conjugate binder fiber that includes a conjugate binder fiber comprising a crystalline polyester resin having a high crystallization temperature and a crystalline polyester resin having a low crystallization temperature and has at least two crystallization temperatures. The crystallization temperature of the crystalline polyester resin having a low crystallization temperature is at least 100°C, and the difference between the crystallization temperature of the crystalline polyester resin having a high crystallization temperature and the crystallization temperature of the crystalline polyester resin having a low crystallization temperature is 5°C or more.

Description

  The present invention relates to a polyester binder fiber that uses polyester fiber as a main fiber and is suitable for paper production.

  Conventionally, polyethylene fibers, polyvinyl alcohol fibers, and the like have been used as papermaking binder fibers, but in recent years, excellent physical properties such as mechanical properties, electrical properties, heat resistance, dimensional stability, hydrophobicity, and cost advantages From the viewpoint of properties, a paper made by a paper making method using polyester fiber as a part or all of a raw material is often used. Furthermore, as the amount and usage of polyester fiber has been expanded, establishment of various technologies such as establishment of production technology aiming to improve yield and production of binder fiber capable of producing high-strength paper is required. It has been.

  However, polyester binder fibers that can produce high-strength paper as a distinctive fiber often cause problems with sticking to rollers in the process due to the loss of binder performance instead of improving paper strength, or improve troubles. Therefore, when binder fibers that are less sticking to the roller are used, problems such as low paper strength occur instead of reducing trouble.

  For the purpose of improving the yield as a past binder fiber, 0.03% by weight or more of a polyether / polyester copolymer is adhered to the fiber surface, and the moisture content retention is 5 to 40% by weight. The unstretched polyester fiber for papermaking (see Patent Document 1), which has excellent water dispersibility in the papermaking process and has excellent thermal adhesiveness, or ethylene terephthalate unit as a hard segment and ε-caprolactone as a soft segment. A core-sheath type composite binder fiber in which a polyester elastomer such as a random copolymer polyester obtained in the above is disposed in the core and a low melting point polymer having a melting point lower than 200 ° C. such as polyethylene terephthalate / polyethylene isophthalate copolymer polyester is disposed in the sheath. Use non-woven fabric with a soft texture and elasticity, or cushion There was a proposal (see Patent Document 2) to obtain polyester solid cotton which is suitable as an agent and has excellent softness and softness when used in a long-term or high-temperature atmosphere. There have been no reports on polyester binder fibers that reduce sticking problems and improve paper strength.

JP 2002-339287 A JP 7-305233 A

  It is an object of the present invention to provide a binder fiber having conflicting characteristics that reduces a sticking trouble in the process and can produce a fiber structure such as high-strength paper or nonwoven fabric in a polyester composite binder fiber. It is.

  As a result of intensive studies to solve the above problems, the present inventors have found that when a binder fiber is produced, a low-viscosity crystalline polyester resin that exhibits a high crystallization temperature in differential heat measurement, and a low crystallization temperature. A binder fiber composed of a composite fiber using a high-viscosity crystalline polyester resin (hereinafter referred to as a composite binder fiber) having at least two crystallization temperatures and crystallization of the lower resin An unstretched polyester-based composite binder fiber having a temperature of at least 100 ° C. or more and a difference in crystallization temperature from a resin having a higher crystallization temperature of 5 to 40 ° C. The present invention has been completed.

  That is, the present invention is a polyester-based composite binder fiber having at least two crystallization temperatures and a temperature difference of 5 ° C. or more and 40 ° C. in differential heat measurement, preferably at least two kinds of crystalline polyesters. Each of the crystalline polyester resins is made of a resin and has a different crystallization temperature. The crystallization temperature of the polyester resin (X) that exhibits a low crystallization temperature is at least 100 ° C. and the crystallization temperature is The polyester-based composite binder fiber described above, wherein the difference in crystallization temperature from the highly expressed polyester resin (Y) is 5 ° C. or more, and more preferably, the resin component of the polyester resin (X) The above polyester in which the ratio of the resin component of the polyester resin (Y) is X / Y = 20/80 to 80/20 (weight ratio). A ether-based composite binder fibers.

For example, when making paper using the polyester-based composite binder fiber of the present invention, the composite binder fiber is softened in the drying step after paper making, and is crushed and deformed into the main fiber, thereby holding the main fiber together. Usually, the temperature set in the drying process after papermaking is about 120 ° C, so the crystallization temperature of the polyester resin (X) constituting the composite binder fiber is designed to be equal to or lower than this temperature. Keep it. As a result, since it is crystallized in the drying process, the amount of deformation is small, and the force to hold the main fibers is weakened, and as a result, paper strength is hardly developed. Further, since the deformation amount of the binder fiber is small, the sticking force to the drying roller is also reduced, and as a result, sticking troubles are reduced. Here, the crystallization temperature of the other component, the polyester resin (Y), is designed to be higher than the drying temperature after papermaking and is dried at a temperature lower than the crystallization temperature. Exists.

  Furthermore, in the calender process which is the next process, the treatment is usually performed at a high temperature of 200 ° C. or higher. Here, a temperature higher than the crystallization temperature of the crystallized polyester resin (Y) constituting the binder fiber is applied, and the main fiber is crystallized while being held. As a result, high paper strength can be expressed.

  The present invention will be described in detail below. The fiber of the present invention melts two or more kinds of crystalline polyester thermoplastic resins having different intrinsic viscosities (hereinafter sometimes referred to as [η]), and the melt is converted into, for example, a known core-sheath type composite Using a spinning pack equipped with a die, it can be produced by spinning with a known spinning device. In addition, since the fiber is used for a binder, it is unstretched or is subjected to a low-magnification stretching treatment that does not crystallize the fiber. Here, the fineness, the crystallization temperature, and the like are adjusted by various conditions such as the discharge amount, the roller speed, and the temperature. Also, heat fixing and crimping are not performed.

  The binder fiber of the present invention is a polyester composed of 85 mol% or more, preferably 95 mol% or more, more preferably substantially all of ethylene terephthalate, based on all repeating units. A component obtained by copolymerizing a component other than the terephthalic acid component and the ethylene glycol component in a small amount (usually 15 mol% or less based on the terephthalic acid component) may be used. These polyesters may contain known additives, pigments, dyes, matting agents, antifouling agents, antibacterial agents, deodorants, fluorescent whitening agents, flame retardants, stabilizers, UV absorbers, lubricants, etc. good.

  The titanium content contained in the polyester resin used in the binder fiber of the present invention is preferably 20% by weight or less. If it exceeds this range, the spinnability is remarkably inferior and it becomes difficult to form a thread. Therefore, it is more preferably 15% by weight or less, and further preferably 10% by weight or less.

  In the polyester binder fiber of the present invention, the [η] of the resin used is in the range of 0.40 to 0.75, more preferably 0.45 to 0.70. If [η] is too low, the spinnability at the time of spinning deteriorates and spinning becomes difficult, which is not preferable. If [η] is too high, the pressure applied to the spin pack becomes too high, resulting in troubles such as breakage of the equipment and inability to discharge from the hole.

  The crystallization temperature of the polyester resin (X) in the differential heat measurement referred to in the present invention is 100 ° C. or higher, more preferably 105 ° C. or higher. In order to lower the crystallization temperature, it is preferable to use a chip having a higher viscosity (for example, [η] is 0.6 or more) or to lower the temperature condition during spinning. If the crystallization temperature of the polyester resin (X) is too low, spinning becomes difficult due to problems such as nozzle pressure. The crystallization temperature of the polyester resin (Y) is preferably 125 ° C. or higher and 140 ° C. or lower. If it is lower than this temperature, the core component is crystallized at the temperature of the drying step, and the intended effect of the present invention is impaired. For the above reasons, in order to obtain characteristics as a composite binder fiber composed of at least two kinds of polyester resin components, the difference in crystallization temperature between the polyester resins is preferably 5 ° C. or more.

  The composite binder fiber of the present invention is produced by melt spinning the above-described at least two kinds of polyester resins with a known spinning device using a spinning pack provided with the above-described known spinneret. The composite binder fiber of the present invention has at least two crystallization temperatures in differential heat measurement, and the temperature difference is 5 ° C. or more and 40 ° C. or less. Since the fiber is used for a binder, it is unstretched or low-stretched so that the fiber does not crystallize. Here, the fineness, the crystallization temperature, and the like are adjusted by various conditions such as the discharge amount, the roller speed, and the temperature. Also, heat fixing and crimping are not performed.

  The fineness of the conjugate fiber of the present invention is preferably in the range of 0.1 to 10 dtex, more preferably 0.5 to 8 dtex. When the fineness is less than 0.1 dtex, it is difficult to twist the composite fiber, and when the paper exceeds 10 dtex, the binder effect is reduced because the number of binder fiber components per unit area of the paper is reduced. This is not desirable because the paper strength is reduced or a paper with uniform paper strength cannot be manufactured.

  The weight ratio (X) / (Y) of the resin component of the polyester resin (X) and the polyester resin (Y) of the binder fiber of the present invention is preferably 20/80 to 80/20. Outside this range, problems such as sticking troubles occur, or conversely, when paper is produced, problems such as the absence of paper strength are likely to occur, and it may be difficult to achieve the desired performance in the resulting composite fiber. In order to express the target performance of the present invention, (X) / (Y) is more preferably 30/70 to 70/30.

  Moreover, it is preferable that the fiber length of the binder fiber of this invention is 0.5-50 mm, Furthermore, 1-25 mm is more preferable. If the thickness is less than 0.5 mm, the number of main fibers to be connected with one binder fiber is reduced, so that when paper is manufactured, paper strength is hardly exhibited. On the other hand, if it exceeds 50 mm, the fibers will be entangled in the paper making, and the part will appear as a paper defect, resulting in poor paper formation, and binder fibers will concentrate on the defective part, resulting in process troubles and reduced paper strength. You may be invited.

  The cross-sectional shape of the binder fiber of the present invention is particularly preferably a core-sheath type, but may have a shape such as a sea-island type, a side-by-side type, or a split type (radiation type, parallel type). Furthermore, in the case of the core-sheath type, the position of the core part with respect to the sheath part may be either concentric or eccentric.

  Furthermore, the moisture content of the binder fiber of the present invention is preferably 50% or less. If the moisture content is higher than this, the oil agent adhered to the fiber surface will flow out, resulting in problems such as poor dispersion.

  About the oil agent adhesion amount of the binder fiber of this invention, it is preferable that it is 0.01 to 10 weight%. If the oil agent adhesion amount is less than 0.01% by weight, the oil agent cannot be applied uniformly, which leads to deterioration of dispersibility during papermaking, and conversely, if more than 10% by weight is adhered, In addition to problems such as sticking with an oil agent, a foaming phenomenon occurs when fibers are dispersed in water during paper making, which significantly deteriorates processability. Therefore, the oil agent adhesion amount of the binder fiber of the present invention is more preferably 0.1 to 3% by weight.

  The binder fiber of the present invention is used for fiber structures, particularly paper and nonwoven fabric applications. In this case, the binder fiber of the present invention is preferably contained in the fiber structure at 10 to 90% by weight. When the content is less than 10% by weight, the amount of the binder fiber is too small, so that it is impossible to join together. On the other hand, when the content exceeds 90% by weight, the amount of the main fiber decreases, and in this case, the strength is not developed. Preferably it is 20 to 80 weight%.

  Hereinafter, although an example explains in detail, the present invention is not limited at all by the example. In addition, the physical property of each fiber in this invention and the physical property of the paper obtained were measured with the following method.

[Fiber fineness dtex]
Evaluation was made according to JIS L1015 “Testing method for chemical fiber staples (8.5.1)”.

[Preparation of evaluation paper sample]
After separating the fibers using a disaggregator, paper was made using a tappy paper machine. Then, after adjusting the moisture using a press, it was dried with a rotary dryer, and a paper for evaluation was prepared by applying a calendar. The equipment and conditions used here are:
-Disintegrator (manufactured by Tester Sangyo Co., Ltd.): 3000 rpm, 1 minute-Paper machine (manufactured by Kumagai Riken Kogyo Co., Ltd.)
・ Press (manufactured by Kumagaya Riki Kogyo Co., Ltd.): 3.5 kg / cm ² for 30 seconds ・ Rotating dryer (manufactured by Kumagai Rikyu Kogyo Co., Ltd.): 110 ° C., 1 minute ・ Hot press: 220 ° C., gap 0.1mm

[Crystallization temperature ° C]
Measurement was performed using “Thermoplus TG8120” manufactured by Rigaku Corporation. Here, the value of the crystallization temperature was obtained by drawing a tangent line in accordance with the waveform of the mountain as shown in FIG. 2 in the curve of FIG.

[Paper strength kg / 15mm]
The measurement was performed according to the JIS P8113 test method.

[Strong sticky g]
A clip is attached to one end of the paper that has passed through the calendar process, and a spring alone is attached to the clip. The spring alone was pulled slowly and the force when the paper was peeled off from the roller was read and used as the measured value.

[Examples 1 to 11 and Comparative Examples 1 to 3]
The main fiber (“EP053 × 5” manufactured by Kuraray Co., Ltd.) was blended at a ratio of 60% by weight and the binder fiber described in Table 1 at a ratio of 40% by weight, and papermaking was performed. The results are shown in Table 1. As shown in Examples 1 to 11, a paper comprising polyester composite binder fibers having at least two crystallization temperatures in differential heat measurement and having a temperature difference in the range of 5 to 40 ° C. A paper having high paper strength and low stickiness was obtained. On the other hand, the paper containing the homobinder fiber which is not the composite fiber of Comparative Examples 1 and 2 has a poor balance between paper strength and sticking strength, and the binder fiber having a small difference in crystallization temperature of Comparative Example 3 has a high target. A strong, low-stick paper could not be obtained.

ADVANTAGE OF THE INVENTION According to this invention, the binder fiber provided with the conflicting characteristic that a fiber structure, such as a highly powerful paper or a nonwoven fabric, can be manufactured can be reduced, and the sticking trouble in a process can be reduced.
The fiber structure such as paper / nonwoven fabric containing the polyester-based composite binder fiber of the present invention is used in applications such as a support for RO membranes, wallpaper, and tea bags.

The schematic diagram which shows one example of the curve measured by the differential heat measurement of the binder fiber of this invention. The schematic diagram which shows the measuring method of the crystallization temperature of the binder fiber of this invention.

Claims (4)

A polyester-based composite binder fiber characterized in that it has at least two crystallization temperatures in differential heat measurement, and the temperature difference is 5 ° C. or more and 40 ° C. or less. Polyester resin comprising at least two types of crystalline polyester resins having different crystallization temperatures, the polyester resin (X) having a low crystallization temperature and having a crystallization temperature of at least 100 ° C. and a high crystallization temperature. The polyester composite binder fiber according to claim 1, wherein the difference in crystallization temperature from (Y) is 5 ° C or more. The polyester composite according to claim 1 or 2, wherein the ratio of the resin component of the polyester resin (X) and the resin component of the polyester resin (Y) is X / Y = 20/80 to 80/20 (weight ratio). Binder fiber.   The fiber structure containing the fiber in any one of Claims 1-3.

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