JP2008138312A - Ceramic filament fabric using paper tape covered yarn and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which weaving can efficiently be carried out for preparing a ceramic filament knitted fabric and to provide an alumina filament fabric having excellent performances while eliminating rusting because hydrogen chloride having strong corrosiveness is contained in an alumina filament precursor and rust is formed in a part such as a latch needle or a guide of a knitting machine which is one cause of damaging the knitting machine when the alumina filament precursor is woven and baked into the alumina filament knitted fabric. <P>SOLUTION: The rusting of knitting machine parts contacting a yarn during the knitting can be suppressed and even fluffing can be eliminated by adopting a covering step of helically winding a paper tape in a non-twist state around a ceramic filament or an alumina filament precursor, a step of knitting the paper tape covered yarn and a baking step of removing the paper tape by incineration and converting the alumina filament precursor into an alumina filament. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ceramic long fiber and an alumina long fiber knitted fabric obtained by firing a knitted fabric made of ceramic long fibers or alumina long fiber precursors covered with a paper tape.

  Ceramic fibers, alumina fibers, and alumina silica fibers are excellent fibers having excellent heat resistance, high strength, and electrical insulation, and are used in a wide range of fields as high temperature heat resistant materials. In addition, these fibers can be knitted and woven to be processed into knitted fabrics. However, these ceramic fibers have extremely low elongation, and because they are hard, knitting machine parts such as knitting machine guides and spatula needles can be used. Since it is damaged, the fabric can be processed relatively easily, but it is difficult to process it into a knitted fabric.

  On the other hand, the present inventors have studied to obtain an alumina long fiber knitted fabric excellent in stretchability and heat resistance, and the alumina long fiber precursor and the reinforcing yarn having a fiber diameter of 30 μm or less in an atmosphere having a relative humidity of 50% or less. Has already proposed a method for producing an alumina continuous fiber knitted fabric having excellent stretchability by twisting, knitting and firing.

However, when trying to knit the alumina long fiber precursor knitted fabric, the strength of the alumina long fiber precursor was weak, so that fluff was easily generated at the time of knitting even though the reinforcing yarn was reinforced. In addition, since aluminum oxychloride is used as a raw material for producing the alumina long fiber precursor, rust is formed on the part where the yarn of the knitting machine passes, for example, a vellus needle, etc., by hydrogen chloride emitted from the precursor fiber surface. Occurred, causing damage to the equipment and poor knitting.
JP 2006-22430 A JP 2006-22431 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an alumina long fiber knitted fabric using a ceramic long fiber precursor that does not cause fuzz and does not damage a device such as a spatula needle of a knitting machine during knitting.

  In order to solve the above-mentioned problems, the present inventors have intensively studied, and as a result, covered the entire fiber surface with a ceramic long fiber or alumina long fiber precursor with paper tape, and knit the resulting cover link yarn into a knitted fabric. After that, the ceramic long fiber knitted fabric can be obtained by burning and removing the paper tape by firing, or at the same time when the paper tape is burned and removed by heating and firing at a higher temperature to transform the precursor fibers into alumina long fibers. The present inventors have found that a fiber knitted fabric can be obtained with high productivity and completed the present invention.

  That is, the gist of the present invention is that (Claim 1) a knitted fabric made of a paper tape covering yarn in which a paper tape is spirally wound around the entire surface of the semi-long filament fiber in a non-twisted state is heated at a temperature of 500 ° C. or less. Ceramic long fiber knitted fabric characterized by (Claim 2) A knitted fabric made of a paper tape covering yarn in which a paper tape is spirally wound around the entire surface of a ceramic long fiber in an untwisted state, and further, the fiber is wound in a spiral shape in the opposite direction to the paper tape. A ceramic long fiber knitted fabric heated at a temperature of 500 ° C. or lower. (Claim 3) A covering process in which a paper tape is spirally wound around the entire surface of a ceramic long fiber, a process of knitting a paper tape cover link yarn, and heating at a temperature of 500 ° C. or less to remove the paper tape by incineration. The method for producing a ceramic long fiber knitted fabric according to claim 1 or 2, comprising a heating step. (Claim 4) An alumina long fiber knitted fabric obtained by firing a knitted fabric comprising a paper tape covering yarn in which a paper tape is spirally wound around the entire surface of an alumina long fiber precursor in an untwisted state. (Claim 5) A paper tape covering yarn in which a paper tape is spirally wound around the entire surface of the alumina long fiber precursor in an untwisted state, and further, the fiber is spirally wound in an opposite direction to the paper tape. An alumina long fiber knitted fabric obtained by firing a knitted fabric. (Claim 6) A covering step in which a paper tape is spirally wound around the entire surface of the alumina long fiber precursor in a non-twisted state, a step of knitting a paper tape cover link yarn, an incineration removal of the paper tape and an alumina long fiber precursor. 6. The method for producing an alumina long fiber knitted fabric according to claim 4 and 5, further comprising a firing step for transforming into alumina long fibers.

  According to the present invention, since the surface of the precursor fiber containing highly corrosive hydrogen chloride is covered with the paper tape over the entire surface, damage to the contact portion with the yarn of the knitting machine can be prevented. In addition, strength reduction due to moisture absorption of the precursor fiber can also be prevented. Further, fluff can be prevented from being scattered. By covering with paper tape, hygroscopicity can be suppressed and a reinforcing effect can be expected. Furthermore, since it is a paper tape, the paper tape can be easily disassembled in a subsequent firing step, and therefore shrinkage of the precursor fibers that occurs during firing can be suppressed to a small extent. In addition, since the covering material is paper, the generation of combustion debris at the time of firing is extremely small, so there is almost no effect on the strength reduction of the alumina long fibers.

  The ceramic long fiber as used in the field of this invention means a silica fiber, an alumina fiber, an alumina silica fiber, etc., and what was heat-fired at the temperature of 1000 degreeC or more. Since the ceramic long fiber is hard and has low bending strength, in the present invention, a paper tape is wound in a spiral shape in a non-twisted state on the entire surface around the yarn. Since the paper tape is wrapped around the entire surface, it is possible to prevent the occurrence of fluff from the yarn during the knitting of the ceramic fiber, and it is also possible to prevent the Bella needle and the guide from being damaged. A ceramic long fiber knitted fabric can be obtained by knitting a covering yarn of a ceramic long fiber paper tape and incinerating the paper tape or the upper winding yarn.

  Further, in order to obtain flexibility in the covering yarn and facilitate knitting, an alumina long fiber precursor can be used instead of the ceramic long fiber. When an alumina long fiber precursor is used, an alumina long fiber knitted fabric can be continuously obtained from the precursor fiber through a knitting and firing process, which is more advantageous than using an already fired ceramic long fiber. However, energy costs are high. Therefore, either method may be adopted depending on the raw material fiber to be used.

  When using the alumina long fiber precursor, the covered paper tape and the upper winding yarn are incinerated and removed in the combustion process, and then the precursor fiber is fired at a temperature of 1000 ° C. or higher to obtain an alumina long fiber knitted fabric.

  When these two types of fibers are used, the same process is adopted until the covering process, which is the greatest feature of the present invention, and the paper tape and the upper winding thread are incinerated and removed. The present invention will be described with reference to FIG. In order to carry out the present invention, it is first necessary to make a paper tape covering yarn of an alumina long fiber precursor (hereinafter sometimes referred to as a core fiber). The alumina long fiber precursor used in the present invention can be obtained by a known method of dry spinning a spinning stock solution comprising aluminum oxychloride, silica sol and polyvinyl alcohol. It is preferable to use a precursor in which the alumina / silica component ratio of the alumina long fiber obtained after the firing step is 40 to 99.5% alumina and the silica is about 0.5 to 60%.

  The diameter of the precursor fiber is 30 μm or less, and the finer the fineness of the yarn, the more preferable. When a thin precursor fiber is used, the amount of paper tape used for the cover link is relatively large, so that the combustion residue is reduced during subsequent firing. This is not preferable since the amount of the generated alumina may be increased, and the strength of the resulting alumina continuous fiber may be lowered. Therefore, yarns of about 50 to 1000 tex are often used, preferably 100 to 300 tex, more preferably about 150 to 250 tex.

  The paper tape used in the present invention is, for example, a paper made of pulp cut into a tape shape, and as the raw material pulp, a long fiber length is preferable from the point of strength, coniferous trees such as pine, leaf vein fibers such as hemp, Pulp made of bast fibers such as kouzo and mitsumata is usually used. In particular, a wide and thin paper tape that can suppress the number of twists of covering and has as little ash as possible when burned is preferably used.

If the basis weight of the paper tape is small, the tensile strength of the paper tape is reduced, so that the tape is likely to be cut in the covering yarn manufacturing process, whereas if it is too large, combustion debris is likely to occur during firing of the precursor fiber knitted fabric, The tensile strength of the alumina long fiber after firing decreases. Basis weight of the order paper tape is preferably 5 to 50 g / m ^2, the range of 8~30g / m ² is more preferably used.

  In addition, the width of the paper tape and the number of covering twists vary depending on the fineness of the precursor fiber that becomes the core fiber, but when the core fiber is as thick as 200 tex, if the width of the paper tape is too narrow, the twist that winds the tape around the core fiber in a spiral shape The tape width is 1 mm or more, preferably in the range of 2 to 6 mm because the number increases, the flexibility is low, and the tensile strength tends to be insufficient, and if the width is wide, winding defects are likely to occur in the covering process. It is.

The number of twists in which the paper tape is spirally wound around the core fiber is preferably in the range of 100 to 600 T / m, particularly 200 to 400 T / m, in view of the tensile strength, texture and covering state of the knitted fabric after firing.

  The method for producing the covering yarn of the present invention is not particularly limited. For example, a double covering device having two hollow spindles as shown in FIG. 2 is preferably used. The bobbin attached to the second hollow spindle has nothing wound or a bobbin wound with normal fibers. The rotation direction of the second hollow spindle is opposite to the rotation direction of the first hollow spindle.

  The core fiber, which is a precursor fiber, is delivered at a constant tension from the delivery device 3 and guided to the first hollow spindle 7. A bobbin dedicated to paper tape is fixed to the first hollow spindle, and rotates simultaneously with the hollow spindle so that the paper tape can be wound spirally around the entire core fiber coming out of the hollow portion without twisting. The untwisted state here means a state in which the paper tape is wound around the core fiber without being twisted.

  The precursor fibers completely covered with the paper tape are guided to the second hollow spindle 8. A normal fiber bobbin is fixed to the hollow spindle, and the fiber rotates in a form that rotates in the opposite direction to the first hollow spindle at the same time as the hollow spindle, and holds the paper tape around the outer periphery of the covering thread coming out of the hollow part. It is wound into a shape. As the upper wound fiber used at this time, any fiber can be used as long as it is thermally decomposed at the time of subsequent firing, but a fiber that does not melt and ashes, such as rayon, is preferable. FIG. 1 shows a schematic diagram of the covering yarn. If nothing is attached to the second hollow spindle, a covering thread is formed by winding a paper tape around the core fiber in a non-twisted state.

  By supplying the core fiber at a constant tension in this way, the generation of fluff due to the core fiber swinging can be suppressed, and the covering yarn of the present invention can be continuously wound without causing yarn breakage. When winding the paper tape, if the rotation speed of the spindle is slowed, the winding stress of the tape is reduced, and an excess portion is generated on the tape, which is crushed by the roller to become a flat yarn. On the other hand, when the rotational speed of the spindle is increased, the winding stress increases and the paper tape tends to be cut. It is preferable to set the spindle rotation speed at which the covering yarn obtained by spirally winding a paper tape around the alumina long fiber precursor is rounded and continuously wound.

  In addition, a covering thread can be manufactured without any trouble by winding the paper tape flat on the paper tape dedicated bobbin with a constant tension and a constant winding pressure. The paper tape dedicated bobbin here refers to a bobbin that can be wound evenly around the bobbin without being twisted by the paper tape dedicated bobbin winder. By using this special bobbin winder for paper tape, it became possible to wind the paper tape flat with a constant tension and a constant winding pressure. When a conventionally used thread bobbin winder is used, biting occurs between the wound paper tapes, making it difficult to supply the paper tape with uniform tension.

  As described above, the alumina long fiber precursor contains liberated hydrogen chloride, so that rust is generated at the contact portion of the knitting machine. The corrosivity of the alumina long fiber precursor before covering and the covering yarn obtained in the present invention was examined. Bella needles were brought into contact with each other in an atmosphere of 20 ° C. and 65% RH and left for 11 days. A large amount of rust was observed at the contact area of the Bella needle in contact with the precursor fiber. On the other hand, the generation of rust was not observed in the covering yarn, and it was found that the anti-rust effect was perfect by covering. This is because covering the entire surface of the core fiber with a paper tape has an effect of shielding hydrogen chloride contained in the precursor fiber.

  When the strength and elongation of the precursor fiber and the covering yarn were compared, the tensile strength increased by 40% or more, although the elongation was slightly decreased by covering the precursor fiber with a twist number of 300 T / m. It was found that a reinforcing effect on the precursor fiber was obtained.

  The present invention will be described below with reference to the drawings and examples. FIG. 1 is a schematic diagram of a covering yarn in which a paper tape is spirally wound around a ceramic long fiber or alumina long fiber precursor in an untwisted state, and a normal yarn is wound in the opposite direction. It is a schematic diagram of an example apparatus which manufactures the covering yarn of invention.

A paper tape having a basis weight of 15 g / m ² and a width of 4 mm was wound around a bobbin for covering paper tape using a bobbin winder for paper tape. In the double covering apparatus shown in FIG. 2, a 200 tex alumina long fiber precursor is used as a core fiber, the above paper tape is wound in a spiral shape at a twist number of 300 T / m, and a 20 tex rayon is twisted at a twist number of 70 T / A covering yarn wound with m was obtained. Table 1 shows the evaluation results of the alumina continuous fiber obtained by firing the obtained covering yarn. Table 2 shows the evaluation results of the alumina continuous fiber knitted fabric obtained by firing the knitted fabric obtained by knitting the covering yarn with a knitted knitting machine.

The firing conditions are as follows. The knitted fabric knitted from the paper tape covering yarn is heated to 350 ° C. at a heating rate of 100 ° C./hr in the furnace to decompose the paper tape and the upper winding yarn, and then heated to 1150 ° C. at 300 ° C./hr. Alumina long fiber knitted fabric was obtained by firing for 1 hour. Table 2 also shows the physical properties of the knitted fabric made of stainless fiber. This knitted fabric is an example of one used as a heat-resistant buffer material for processing tempered glass.

  A covering yarn was obtained in the same manner as in Example 1 except that the paper tape and the alumina long fiber precursor used in Example 1 were used and the numbers of twists were set to 200 T / m, 400 T / m, and 600 T / m. The obtained covering yarn was fired under the same conditions as in Example 1, and the evaluation results of the obtained alumina continuous fiber are shown in Table 1.

  A covering yarn was obtained in the same manner as in Example 1 except that the width of the paper tape was changed to 2 mm and the number of twists was changed to 600 T / m. Table 1 shows the evaluation results of the alumina continuous fiber obtained by firing the obtained covering yarn.

  Paper tape and rayon yarn were covered in the same manner as in Example 1 using alumina long fibers of alumina: silica = 70: 30. A knitted fabric obtained by knitting the covering yarn with a knit knitting machine was fired at 400 ° C. to obtain an alumina continuous fiber knitted fabric. Further, the alumina long fiber after firing the covering yarn at 400 ° C. had no physical property change at a temperature of about 400 ° C., and had the physical properties of the original alumina long fiber. Further, during the knitting, the entire surface of the alumina long fiber was covered with a paper tape, so that the knitting machine parts were not damaged.

(Comparative Example 1)
A paper tape having a basis weight of 15 g / m ² and a width of 2 mm was wound around a bobbin for covering paper tape with a bobbin winder for paper tape. In the double covering apparatus shown in FIG. 2, a 70 tex alumina long fiber precursor is used as a core fiber, the above paper tape is wound in a spiral shape at a twist number of 400 T / m, and a 20 tex rayon is twisted at a twist number of 70 T / m A covering yarn wound with m was obtained. Table 1 shows the evaluation results of the alumina continuous fiber obtained by firing the obtained covering yarn.

(Comparative Example 2)
A covering yarn was obtained in the same manner as in Example 1 except that 30 tex cotton yarn was used instead of the paper tape and the twist number was 1200 T / m. Table 1 shows the evaluation results of the alumina continuous fiber obtained by firing the obtained covering yarn.

  In this way, when a yarn such as cotton yarn is covered instead of paper tape, the surface of the precursor fiber is not sufficiently covered even if the number of twists is 1200 T / m, and moisture absorption of the precursor fiber is prevented. It cannot be done, and the fiber surface was damaged by rubbing with a guide is considered to be a cause of a decrease in strength retention.

  The ceramic long fiber knitted fabric or the alumina long fiber knitted fabric obtained by the present invention has no fluff and has both stretchability and bulkiness, so that it can be attached to an object having a complicated shape. For example, it can be used as a tempered glass molding protective material used when producing curved glass. As shown in Table 2, even when compared with a stainless steel knitted fabric used as a heat-resistant cushioning material for tempered glass processing, it has excellent physical properties, does not generate rust, is light, and is easy to handle. It has the characteristics such as.

The schematic diagram of the covering thread | yarn obtained by this invention. The schematic diagram which shows an example of the double covering apparatus for implementing this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic long fiber or Alumina long fiber precursor 2 Paper tape 3 Yarn supply roller 4 Guide 5 Supply guide tube and spindle 6 Balloon guide 7 Paper tape bobbin 8 Upper wound thread bobbin 9 Upper wound fiber
10 Winding yarn

Claims (6)

  A ceramic long fiber knitted fabric, wherein a knitted fabric made of a paper tape covering yarn in which a paper tape is spirally wound in an untwisted state around the ceramic long fiber is heated at a temperature of 500 ° C. or lower.   A knitted fabric made of a paper tape covering yarn in which a paper tape is spirally wound around the entire surface of a ceramic long fiber in an untwisted state, and the fiber is spirally wound in the opposite direction to the paper tape on the upper winding at a temperature of 500 ° C. or lower. Ceramic long fiber knitted fabric characterized by being heated in   It comprises a covering process in which a paper tape is spirally wound around the entire surface of the ceramic long fiber in an untwisted state, a process of knitting a paper tape covering yarn, and a heating process in which the paper tape is incinerated and removed by heating at a temperature of 500 ° C. or lower. The method for producing a ceramic long-fiber knitted fabric according to claim 1 or 2, characterized in that.   An alumina long fiber knitted fabric obtained by firing a knitted fabric made of a paper tape covering yarn in which a paper tape is spirally wound around an entire surface of an alumina long fiber precursor in an untwisted state.   A knitted fabric made of a paper tape covering yarn in which a paper tape is spirally wound around the entire surface of the alumina long fiber precursor in a non-twisted state, and the fibers are spirally wound in the opposite direction to the paper tape. Alumina long fiber knitted fabric characterized by   Covering process in which paper tape is spirally wound around the entire surface of the alumina long fiber precursor in a non-twisted state, a process of knitting the paper tape covering yarn, the paper tape is incinerated and removed, and the alumina long fiber precursor is transformed into alumina long fibers. The method for producing an alumina continuous fiber knitted fabric according to claim 4 or 5, comprising a firing step.

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