JP2002061057A - Highly heat-conductive heat-resistant felt material having excellent abrasion resistance of surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly heat-conductive heat-resistant felt material comprising a heat-resistant fiber having excellent thermal conductivity. SOLUTION: This highly heat-conductive heat-resistant felt material is a felt material constituted of a heat-resistant organic fiber such as mainly a polybenzazole fiber, etc., having >=0.2 g/cm3 apparent density, >=0.7 W/m.K heat conductivity in the thickness direction and >=4 class abrasion resistance on the surface of the felt measured by JIS L 1913 taber method and excellent surface abrasion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant cushioning material for the purpose of preventing scratches on high-temperature products in the manufacturing process of steel, ceramics, non-ferrous metals and the like.

[0002]

2. Description of the Related Art In a manufacturing process in the fields of steel, ceramics, non-ferrous metals, etc., it is necessary to support a high-temperature product without damaging the product, and a heat-resistant cushion material mainly made of heat-resistant organic fibers is used. . Here, para-aramid fiber, meta-aramid fiber, flame-resistant fiber and the like are generally used as the material of the heat-resistant fiber, and the heat-resistant cushion material is used alone or in combination with the heat-resistant fiber. As an example thereof, a cushioning material made of a high heat-resistant fiber obtained by blending an aromatic polyamide fiber and a ceramic fiber and performing needle punching (for example, JP-A-7-34)
No. 367), a heat-resistant felt for high-temperature products which is needle-punched by blending metal fibers and inorganic fibers (for example, Japanese Patent Application Laid-Open No. 08-296160), and an inorganic material having a basalt fiber as a main material and having bending resistance and wear resistance. Heat-resistant needle felt obtained by mixing fibers, metal fibers, and heat-resistant organic fibers (for example, Japanese Patent Application Laid-Open No. 11-200211).
However, heat-resistant cushion materials made of metal fibers, inorganic fibers, basalt fibers, etc. are fragile and harder than heat-resistant cushion materials made of heat-resistant organic fibers, so they have poor abrasion resistance and also damage high-temperature products. There was a problem of putting it.

Therefore, a heat-resistant cushioning material composed of a mixture of heat-resistant fibers typified by para-aramid fibers alone or oxidized fibers made by heat-treating acrylic fibers (for example, trade name "Pyromex") is used. It has already been put into practical use and has achieved certain results.
However, in the manufacturing processes of steel, ceramics, non-ferrous metals, etc., the temperature of high-temperature products immediately after forming is often used at 350 ° C or higher. There was a problem that had to be done.

[0004] In addition, the heat-resistant cushioning material used in the above applications is often used in a cooling step, and a high thermal conductivity is desired even though it is a heat insulating material. There was a problem that the effect could not be obtained. As a method for solving this problem, a high heat conductive heat resistant felt material (for example, Japanese Patent Application No. 11-259229) has already been filed, and in the case of a needle punch felt made of a high heat conductive heat resistant fiber, the surface of the felt is felt from the thickness direction of the felt. High heat conduction is realized by geometrically utilizing the feature that heat conductivity is extremely high in a parallel direction (in-plane direction). However, it has not been possible to achieve a thermal conductivity of 0.7 W / m · K or more in the thickness direction of the felt without the above-described geometrical utilization. Also, increasing the number of needle punching makes it easier to cut the fiber during needle punching, and the cut fiber has a problem of adversely affecting the abrasion of the felt surface.
Heretofore, a heat-resistant felt material mainly composed of a heat-conductive organic fiber having high heat conductivity, without impairing the abrasion of the felt surface, and having a thermal conductivity of 0.7 W / in the thickness direction of the felt.
mK or more could not be realized.

[0005]

The object of the present invention is to solve the above-mentioned drawbacks, and an object of the present invention is to provide a high thermal conductivity made of a fiber having excellent heat resistance and thermal conductivity and having good surface wear resistance. It is intended to provide a heat-resistant felt material.

[0006]

Means for Solving the Problems The present inventors have found that in the case of a felt material using an organic fiber having a high thermal conductivity comparable to that of a metal in the fiber axis direction, such as a polybenzazol fiber or a high-strength polyethylene fiber, The thermal conductivity is governed by the orientation of the fibers in the felt, and by setting the needle depth to the optimum value in the needle punch manufacturing conditions, the surface wear resistance of the felt surface opposite to the punched side The inventors have found that the properties have been greatly improved, and have completed the invention.

That is, the present invention relates to a felt material mainly composed of heat-resistant organic fibers and having an apparent density of 0.2 g / cm ³ or more. Is a high heat conductive heat-resistant felt material having good surface wear resistance, characterized in that the material has a class 4 or higher and a thermal conductivity in the thickness direction of 0.7 W / m · K or more. Is a high heat conductive heat resistant felt material as described above, wherein the heat resistant organic fiber is a polybenzazole fiber. Hereinafter, the present invention will be described in detail.

[0008] The polybenzazole fiber refers to a fiber made of a polybenzazole polymer, and the polybenzazole (hereinafter, also referred to as PBZ) is a polybenzoxazole (hereinafter, also referred to as PBO) homopolymer, a polybenzothiazole (hereinafter, referred to as PBO). (Hereinafter also referred to as PBT) homopolymer and random, sequential or block copolymer of PBO and PBT. Where PBO, PB
T and their random, sequential or block copolymers are disclosed, for example, in Wolfe et al.
ystalline Polymer Compositions, Process and Produc
ts "U.S. Pat. No. 4,703,103 (October 2, 1987)
7) "Liquid Crystalline Polymer Compositions,
Process and Products, US Patent No. 4,533,692 (August 6, 1985), "Liquid Crystalline Poly"
(2,6-Benzothiazole) Compositions, Process and Produ
cts "U.S. Pat. No. 4,533,724 (August 6, 1985)
Sun), "Liquid Crystalline Polymer Compositions, P
"Rocess and Products" U.S. Pat. No. 4,533,693 (August 6, 1985); Evers, "Thermooxidatively
Stable Articulated p-Benzobisoxazole and -Benzobis
thiazole Polymers "U.S. Pat. No. 4,539,567 (1.
November 16, 982), “Method formaking” by Tsai et al.
Heterocyclic Block Copolymer '' U.S. Pat.
432 (March 25, 1986) and the like.

The structural unit contained in the PBZ polymer is preferably selected from a lyotropic liquid crystal polymer. The polymer is selected from the monomer units described in Structural Formulas (a) to (h), and more preferably consists essentially of the monomer units selected from Structural Formulas (a) to (d).

[0010]

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[0011]

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The polybenzazole fiber is produced from a dope containing a PBZ polymer. Suitable solvents for preparing the dope include cresol and a non-oxidizing acid capable of dissolving the polymer. . Examples of suitable non-oxidizing acids include polyphosphoric acid, methanesulfonic acid and concentrated sulfuric acid or mixtures thereof. Among them, polyphosphoric acid and methanesulfonic acid, particularly polyphosphoric acid, are preferred.

[0013] The polymer concentration in the dope is preferably at least about 7% by weight, more preferably at least 1% by weight.
It is 0% by weight, particularly preferably at least 14% by weight. The maximum concentration is limited by practical handling properties such as, for example, polymer solubility and dope viscosity. Because of these limiting factors, the polymer concentration usually does not exceed 20% by weight.

[0014] Suitable polymers, copolymers or dopes are synthesized by known techniques. See, for example, Wolfe et al., US Pat. No. 4,533,693 (August 6, 1985);
U.S. Pat. No. 4,772,678 to S. bert et al. (September 20, 1988); U.S. Pat.
(July 11, 1989). P
BZ polymers are described in US Pat. No. 5,085,959 to Gregory et al.
According to No. 1 (February 8, 1992), it is possible to increase the molecular weight at a high reaction rate under a relatively high temperature and high shear condition in a dehydrating acid solvent. From the dope thus prepared, a known method (for example, US Pat.
5,702 (January 31, 1995)) to produce polybenzazole fibers. The obtained polybenzazole fiber is further subjected to a normal crimping step and a cutting step, and is processed into a short fiber of polybenzazole fiber.

As a method for producing a felt containing polybenzazole fibers, a known method for producing a nonwoven fabric can be applied. Generally, the felt is produced by forming a web from short fibers and performing needle punching. The needle punch method is adopted.

The felt material can mix different types of fibers, and it is effective to increase the mixing ratio of polybenzazole fibers as the requirement for thermal conductivity increases and as the requirement for heat resistance increases. . The weight fraction of the polybenzazole fiber is preferably at least 50%. If it is less than 50%, the excellent high thermal conductivity and heat resistance of the polybenzazole fiber may not be sufficiently exhibited. Specific examples of the fiber to be mixed include para-aramid fiber (trade name “Kevlar”, etc.), meta-aramid fiber (trade name “Nomex”, etc.), polyimide fiber (trade name “P84”, etc.), and oxidized fiber (trade name “ Pyromex "), and heat-resistant fibers having softness are preferred,
Heat-resistant fibers such as carbon fiber, glass fiber, stainless steel fiber, and basalt fiber can also be mixed. As a mixing method, a fiber that is uniformly mixed is made into a felt, or the fibers to be mixed with the polybenzazole fiber are separately made into felts, and then these are laminated in two or more layers, or any shape can be formed as a felt. A method is also acceptable.

A first feature of the felt material according to the present invention is that the felt material contains a high heat conductive organic fiber as a composition. High heat conductivity heat-resistant organic fibers are those having a thermal conductivity of 10 W / m · K or more in the fiber axis direction and a residual weight of less than 90% when subjected to thermogravimetric analysis at a heating rate of 20 ° C./min. Organic fiber whose temperature is 500 ° C or higher. In addition to polybenzazole fiber, for example, poly
[2,6-diimidazo [4,5-b: 4'5'-e] pyridinylene-1,4 (2,5-d
Fibers composed of a polymer having a rigid molecular structure such as [ihydroxy) phenylene]. High heat conductivity Unless heat-resistant organic fibers are used, sufficient heat resistance of the felt material cannot be obtained, and even if the fiber orientation in the felt material is controlled, the apparent density is low. Cannot greatly improve the quality.

The second feature of the felt material according to the present invention is that the apparent density is 0.2 to 0.5 g / cm ³ . This is because if the apparent density is less than 0.2 g / cm ³ , the air layer increases and the thermal conductivity decreases. And 0.5g / c in consideration of cushioning
m ³ or less is desirable. Preferably 0.3 to 0.4 g / c
m is ^3.

A felt produced by forming a web from short fibers and performing needle punching can increase the number of needle punches so that polybenzazole fibers having high thermal conductivity can be oriented in the thickness direction of the felt. FIG. 1 shows the correlation between the thermal conductivity in the thickness direction of the felt and the number of needle punching in a needle punch felt made of polybenzazole fiber. By increasing the number of needle punching, the number of needle punching felts according to the present invention can be improved. The thermal conductivity in the thickness direction of the felt, which is the third feature, can be 0.7 W / m · K or more. As a result, compared to a material having a thermal conductivity of 0.15 W / m · K or less, which is generally called a heat insulating material, the material has excellent heat conductivity and receives heat received from a high-temperature product during transportation. It is easy to release to the outside, which allows the heat-resistant felt material to have a long life.

The thermal conductivity referred to here is JIS-A-
1412, steady GHP based on ASTM-C-177
Method (GuardedHotPlate method)
It refers to the value of the thermal conductivity when measured by sandwiching a heat-resistant felt between two hot plates having a temperature difference under a high temperature condition of 00 ° C.

Of the manufacturing conditions in the needle punching method, the room temperature surface abrasion resistance of several levels of felt made of polybenzazole fibers obtained by needle punching with only a few changes in the needle depth was evaluated. Room temperature surface wear resistance of the punched surface was not good regardless of the needle depth, but when needle punching was performed at a certain needle depth, the room temperature surface wear resistance of the felt surface opposite to the needle punched surface was very good Met. Thus, the felt material according to the present invention, by setting the needle depth to the optimum value among the needle punch manufacturing conditions and designing the felt so that the felt surface opposite to the needle punched surface becomes the surface of the final finished felt. The fourth feature of the present invention is that the surface of the felt measured by the JIS L 1913 Taber method has a wear strength of class 4 or higher. As a result, the room temperature wear resistance of the felt surface is improved, and the removal of fibers from the felt surface is suppressed, so that the heat-resistant felt material can have a longer life.

The normal temperature surface abrasion resistance referred to herein is JIS.
L 1913 Refers to the abrasion strength of the felt surface measured by the Taber method.

The high heat conductive heat-resistant felt material of the present invention comprises:
It can be used for transporting high-temperature objects in the field of metal forming such as aluminum, iron, copper, etc., and in the field of forming ceramics, and its temperature range and usage are not limited. The effect can be exerted when conveying a high-temperature object of at least ℃.

[0024]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to the embodiments.

(Example 1) Fineness of 1. manufactured by Toyobo Co., Ltd.
5 denier, 44 mm cut length PBO fiber staple is opened with an opener and then weighted with a roller card 4
A web of 00 g / m ² was prepared, and the obtained webs were sequentially laminated to form a needle manufactured by Foster (product number: 15 × 18).
× 40 × 3.5PB-A F20 2-18-3B / LI
/ CC / CONICAL) at a needle depth of 7 mm,
Needle punching number 2 only from one side of felt
Needle punching until 000 / cm ² , thickness 9.5 mm, basis weight 3600 g / m ² , density 0.38 g
/ M ³ of felt. The surface opposite to the punched surface was taken as a felt surface. The thermal conductivity of the formed felt material was evaluated as 3 in accordance with JIS-A-1412.
Thermal conductivity measurement under the condition of 00 ° C (test plate area 100
cm ² and a test plate temperature difference of 10 ° C.), the thermal conductivity was 1.07 W / m · K. In addition, JIS L
As a result of evaluating the abrasion resistance by the 1913 Taber method, the abrasion strength of the felt surface was quaternary. Further, FIG.
Using a high-temperature wear test machine such as that shown in, 50 when the sample is rotated at 300rpm a heated friction element to 400 ° C. in a state of being contact with the sample under a load of 500 g / cm ²
When the abrasion resistance was evaluated based on the weight loss due to abrasion after time, the abrasion amount was 2.0 mg / cm ² .

(Embodiment 2) Changing the needle depth to 9 mm,
Other needle punching conditions were the same as in Example 1, needle punching was performed, the thickness was 9.0 mm, and the basis weight was 360.
A felt having a density of 0 g / m ² and a density of 0.40 g / m ³ was obtained. The surface opposite to the punched surface was taken as a felt surface. When the thermal conductivity was measured and the surface wear resistance and the high-temperature wear resistance test were performed in the same manner as in Example 1, the thermal conductivity was 1.02 W / m ·.
The wear strength of the surface of K and felt was grade 4, and the amount of wear in a high-temperature wear resistance test was 2.3 mg / cm ² .

(Comparative Example 1) Needle punching was performed under exactly the same needle punching conditions as in Example 1, thickness 9.5 mm, basis weight 3600 g / m ² , density 0.38 g /
m ³ of felt was obtained. The punched surface was used as a felt surface. The thermal conductivity was measured and the surface wear resistance and the high-temperature wear resistance test were performed in the same manner as in Example 1. As a result, the thermal conductivity was 1.
07 W / m · K, the wear strength of the felt surface was class 3, and the wear amount by a high-temperature wear resistance test was 6.0 mg / cm ² .

(Comparative Example 2) Needle punching was carried out under exactly the same needle punching conditions as in Example 2, thickness 9.0 mm, basis weight 3600 g / m ² , density 0.4 g / m ³
Got the felt. The punched surface was used as a felt surface. Thermal conductivity measurement and surface wear resistance as in Example 1,
A high-temperature wear resistance test showed that the thermal conductivity was 1.02.
W / m · K, the wear strength of the felt surface was grade 3, and the wear amount by a high-temperature wear resistance test was 5.0 mg / cm ² .

(Comparative Example 3) The needle depth was changed to 5 mm,
Other needle punching conditions were the same as in Example 1, needle punching was performed, thickness was 10.5 mm, and basis weight was 36.
A felt having a density of 00 g / m ² and a density of 0.34 g / m ³ was obtained.
The surface opposite to the punched surface was taken as a felt surface.
When the thermal conductivity measurement, the surface wear resistance and the high-temperature wear resistance test were performed in the same manner as in Example 1, the thermal conductivity was 0.95 W / m.
-The wear strength of the surface of K and felt was grade 3, and the amount of wear in a high temperature wear resistance test was 9.5 mg / cm ² .

(Comparative Example 4) Needle punching was carried out in the same manner as in Comparative Example 3, with a thickness of 10.5 mm and a basis weight of 3600 g /
A felt having m ² and a density of 0.34 g / m ³ was obtained. The punched surface was used as a felt surface. When the thermal conductivity was measured and the surface wear resistance and the high-temperature wear resistance test were performed in the same manner as in Example 1, the thermal conductivity was 0.95 W / m · K, the wear strength of the felt surface was grade 3, and the temperature was high. The wear amount by the wear resistance test is 1
It was 0.5 mg / cm ² .

(Comparative Example 5) A thickness of 11.0 mm, a basis weight of 3600 g / m ² , and a density of 0.3 were prepared by needle punching using a staple of 44 mm cut length of para-aramid.
3 g / m ³ of felt was obtained. When the thermal conductivity was measured and the surface wear resistance and the high-temperature wear resistance test were performed in the same manner as in Example 1, the thermal conductivity was 0.24 W / m · K, the wear strength of the felt surface was grade 4, and the temperature was high. The amount of abrasion in the abrasion resistance test was 63.
It was 4 mg / cm ² .

Comparative Example 6 A staple of para-aramid and oxidized fiber was mixed at a ratio of 3: 7, and the resulting mixture was needle-punched to have a thickness of 11.0 mm and a basis weight of 3900 g / m ² .
A felt having a density of 0.35 g / m ³ was obtained. When the thermal conductivity was measured and the surface wear resistance and the high-temperature wear resistance test were performed in the same manner as in Example 1, the thermal conductivity was 0.27 W / m · K, the wear strength of the felt surface was grade 4, and the temperature was high. The abrasion loss in the abrasion resistance test was 119.3 mg / cm ² .

Table 1 summarizes the above experimental results. Compared with the comparative example, the felts of the examples have excellent heat resistance and thermal conductivity,
It is clear that the wear resistance of the felt surface, especially at high temperatures, is by far the best.

[0034]

[Table 1]

[0035]

According to the present invention, it has become possible to provide a high heat conductive heat resistant felt material made of heat resistant fibers having excellent heat conductivity and having good surface wear resistance.

[Brief description of the drawings]

FIG. 1 is a graph showing the correlation between the thermal conductivity in the thickness direction of the felt and the number of needle punching.

FIG. 2 is a schematic diagram showing a high-temperature wear resistance measuring instrument used for measuring wear resistance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High thermal conductive heat resistant felt 2 Heater 3 Friction element 4 Weight 5 Motor 6 Sample folder 7 Sample

Claims (2)

[Claims] 1. A felt material mainly composed of heat-resistant organic fibers having an apparent density of 0.2 g / cm ³ or more, a thermal conductivity in a thickness direction of 0.7 W / m · K or more, and A high heat conductive heat resistant felt material having good surface wear resistance, characterized in that the surface of the felt has a wear resistance of at least class 4 as measured by JIS L 1913 Taber method. 2. The high heat conductive heat resistant felt material having good surface wear resistance according to claim 1, wherein the heat resistant organic fiber is a polybenzazole fiber.