JPS63315699A - Heat resistant sheet like article - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention has low heat shrinkage even at high temperatures above the melting point.
A heat-resistant sheet with excellent legal stability is obtained by mixing short fibers of aromatic polyamide fibers with excellent shape stability and aromatic polyamide pulp grains F-(fibrids), and then heating and pressurizing the paper. It is related to things like this. The heat-resistant sheet material according to the present invention has excellent high-temperature stability, and exhibits the excellent properties of aromatic polyamides, such as heat resistance, flame retardance, electrical properties, chemical stability, and mechanical properties. Because it is equipped with
It can be widely used as a heat insulating board, heat-resistant cushion material, or honeycomb-like structural material.

[Conventional technology]

It is known that aromatic polyamide fibrids and short ya fibers are mixed into a heat-resistant sheet-like material, and that the sheet is made into a honeycomb-like structure. In particular, poly(metaphenylene isophthalamide) (PM (abbreviated as A)),
Paper-like materials made of v-short fibers and fibrids are useful as heat-resistant insulating papers, making it possible to reduce the size and weight of electric motors and transformers. It is also used as a heat-resistant gasket or heat insulating sheet, and honeycomb structures are also made by secondary cutting of the sheet. These PMIA and v-sheets have excellent thermal oxidation resistance and can maintain their physical properties for a long period of time even at high temperatures of 200°C, but the glass transition temperature (Tg, approx. 2
80℃) or high temperatures close to the melting point (Tm, approximately 425℃), short fibers or fibrids undergo rapid thermal contraction and thermal agglutination, deforming the paper-like material, and also decreasing mechanical properties, thermal insulation properties, There were problems such as a decrease in electrical insulation or flexibility.

For this reason, sheets of para-aromatic polyamide fibers such as poly(para-phenylene terephthalamide) or fibrids obtained by beating these fibers are also produced, or due to the rigidity of short fibers or fibrids, Mechanical strength or electrical properties were also insufficient.

[The problem that the invention attempts to solve]

In view of the problem of the aromatic polyamide sheet described above, the present inventors have discovered that the aromatic polyamide sheet has good texture, is homogeneous, and has sufficient mechanical properties.
In order to produce a sheet-like product with excellent shape stability at high temperatures, we conducted various studies from the viewpoint of polymer structure and fiber properties.
This has led to the present invention.

[Means for solving problems]

That is, the present invention Tm2350℃, Tn+-Tex230℃.

×c≧lO%, De≧10%.

Dsr (Tm) 515%, and Dsr (Tm + 55° C.) /Dsr (Tm)≦3 Here, the characteristic values and physical property values respectively represent values obtained with the measuring equipment and measurement conditions described below.

Tm: Melting point [using PerkinElmer's DSC-2G, place an approximately long sample into an An sample dish and heat from room temperature to a specified temperature at a heating rate of 10°C per minute in a nitrogen gas stream (30ml/n+in). 080 curve is obtained, and its endothermic peak temperature is set as Tra. ], Tex: exotherm onset temperature [DSC manufactured by PerkinElmer
-2C, put about 10 mg of sample into a He2 sample dish and heat it in a nitrogen gas stream (JOml/min) at 1 minute per minute.
A 080 curve from room temperature to a predetermined temperature is obtained at a heating rate of 0° C., and its exothermic start temperature is defined as Tex. ], Xc: Crystallinity [Rotating anticathode ultra-strong X-ray generator R manufactured by Rigaku Denki Co., Ltd.
X-ray diffraction intensity in the range of diffraction angles from 2θ-5” to 35° was obtained by using an AD-R8 (40 Vroom 8, 2 lines Cu) and rotating the sample in a plane perpendicular to the X-ray beam. curve, and then divide the diffraction curve into crystalline regions (Ac) and amorphous regions (Aa
), the value x c calculated by the following formula is the crystallinity, Xc = (heC/hec + Aa) 10cm, tensile speed 5cm 15 minutes, initial load 0°05
It was determined by conducting a tensile test under the condition of g/d.

Dsr (Tm): Dry heat shrinkage rate at melting point (%)
Dsr (Tm + 55°C): Dry heat shrinkage rate (%) at melting point + 55°C, and Dsr was measured using the following formula.

In the formula, 10: Length of the m-group sample when a load of 0.1 g/d is applied, ul: The above sample is dried in a hot air dryer at a predetermined temperature.
Treated free for 0 minutes, then 0.1 again after 30 minutes.
Sample length measured with a weight of g/d. ] The present invention relates to a sheet-like product having excellent high-temperature dimensional stability obtained by mixing aromatic polyamide short fibers and aromatic polyamide pulp particles, which are characterized by the following formula, and then heating and pressurizing the paper.

That is, the short fibers used in the sheet material of the present invention have a crystallinity (Xc) of 10% or more and a melting point (Tm) of 350°C.
It is a non-rigid fiber with the following high-temperature properties and an elongation (De) of 10% or more.
Tex) is 30°C or more lower than the melting point, and the fiber has an extremely low thermal shrinkage rate at high temperatures above the melting point.The bulb particles are made from the same or different aromatic polyamide as the short fiber. This is a manufactured amorphous fibrin.

Preferably, the short fibers used for forming the sheet-like article of the present invention are aromatic polyamides satisfying the above-mentioned characteristic values, particularly at the ortho position of the phenylene group directly connected to the nitrogen atom and/or carbon atom of the amide bond. The fibers are preferably made of an aromatic polyamide having a specific structure having a functional group selected from a lower alkyl group having 1 to 4 carbon atoms, an amino group, a sulfone group, a carboxyl group, a hydroxyl group, or a halogen atom.

The aromatic polyamide of the present invention can be easily produced by a known production method. That is, aromatic diamine and aromatic dicarboxylic acid halide can be produced by low-temperature solution polymerization, low-temperature interfacial polymerization, or melt polymerization. It can also be produced from aromatic diisocyanate and aromatic dicarboxylic acid halide by high-temperature solution polymerization.

Examples of raw materials for producing the aromatic polyamide of the present invention include the following, but the raw materials are not limited to these. Examples of aromatic diamines include l,3-phenylenediamine, 1,4-phenylenediamine, tolylene-2,4-diamine, tolylene-2,6-diamine,
2-methyl-1,4-phenylenediamine, 4-chloro-1,3-phenylenediamine, 2-chloro-1,4-
Phenylenediamine, 4-hydroxy-1,3-phenylenediamine, 2-hydroxy-1,3-phenylenediamine, 2-hydroxy-1,4-phenylenediamine, 1,2.4-triaminobenzene, 2.4 -Diaminobenzenesulfonic acid, 2,5-diaminobensenesulfonic acid, 2,4-diamino-benzoic acid, 2,5-diamino-benzoic acid, 2,4-diaminotoluene-5-3,3-
Examples include dichloro-4,4"-diphenyldiamine. Examples of aromatic dicarboxylic acid halides include isophthalic acid dichloride, terephthalic acid dichloride, and 4-
Examples include chloro-isophthalic acid dichloride, 2-bromo-terephthalic acid dichloride, 2,5-dichloroterephthalic acid dichloride, and the like.

Examples of paternal Group 6 diisocyanates include l,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, 2-methyl-1,
4-phenylene diisocyanate, 4-chloro-1,3
-phenylene diisocyanate, 4-bromo-1,3-
Phenyl diisocyanate, 2-chloro-1,4-phenylene diisocyanate, 4-methyl-6-bromo-
1,3-phenylene diisocyanate, 3.3-dimethyldiphenyl-4,4-diisocyanate, 3.3-
Examples include dichlorodiphenyl-4,4-diisocyanate. Examples of aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, and 4-croic acid. In these combinations, either the base component or the acid component contains at least one lower alkyl group, a functional group selected from amino, a sulfone group, a carboxyl group, a hydroxyl group, or a halogen atom. It is essential to use a monomer substituted with , for example, when using a carboxylic acid without a substituent such as isophthalic acid or terephthalic acid, it is necessary to use an isocyanate with the above-mentioned substituents. be.

Further, among the aromatic polyamides produced by these methods, an aromatic polyamide having a particularly preferable structure as short fibers used for producing the sheet-like article of the present invention has the following formula (8) (-11N-^rl -1INO[; -8r2-)
...(8) N remainder J, 1:. xl
represents a lower alkyl group having 1 to 4 carbon atoms or a halogen atom, and the position of the nitrogen atom directly connected to the phenylene residues J and H is the 2.4th or 2.6th position with respect to xl,
And note 2, 4 position: 2. 6 position is 100: O~BG+2
0 or O: It has a turning unit in the range of 100 to 20:80. Ar2 is a divalent phenylene residue represented by phenylene J, 11. The carbonyl group directly connected to is at the 1,4 or 1.3 position, and the 1.4 position - 1,3 position 7) 100:Q to 80:20
Hit the Engaeshi unit within the range of . ) is a y6 group polyamide containing repeating units specified by ). One of these days,
Particularly preferred specific monoaromatic polyamides include 95 mol% or more of repeating units, 4-methyl-1,3-phenylene terephthalamide, or 4-chloro-1,3-
Phenylene terephthalamide, 2-methyl-1,4-phenylene isophthalamide, 3,3゛-dimethyl-4,
Examples include 4°-diphenylisophthalamide.

Next, the production of aromatic polyamide staple fibers used in the sheet-like article of the present invention will be described. A polymerization solution prepared by the method disclosed in Japanese Patent Application No. 60-030529, which was separately invented by the present inventors, is used as a spinning stock solution.
30~too℃, coagulation bath composition; CaCl230~50
% aqueous solution, coagulation bath temperature; wet spinning under conditions of 50 to 100°C, then wet heat stretching 1.1 to 5 times in an aqueous solution bath with almost the same composition as the coagulation bath, and then 50 to 100°C
After thorough washing in hot water, dry with hot air at 100-200°C, and then dry-heat stretch by 1.1-5 times in air at 300-450°C or in an inert gas bath. This makes it possible to produce homogeneous heat-resistant aromatic polyamide fibers with excellent shape stability at high temperatures.

And the fiber is 5 to 20 mm, preferably 5 to 1 Omm.
Cut to length. The shape of the short fibers used in paper making also reflects the physical properties of the sheet material, and must be determined to satisfy the physical properties suitable for the purpose of the sheet material. The short fibers must be manufactured by controlling their thickness, length, cross-sectional shape, surface texture, etc. so that the fibers are entangled with each other in a good fractional state and the sheet-like product has good uniformity.

The aromatic polyamide bulb particles used in the present invention have a glass transition temperature of 220°C or higher, preferably 250°C or higher,
More preferably, it is manufactured from an aromatic polyamide having a temperature of 280° C. or higher, and all known aromatic polyamides can be used for this purpose. Bulb particles are produced by precipitating a solution of polyamide in a polar solvent into fine fibrillar particles by introducing it into a precipitating agent under high shear forces.

As the polar solvent, 3n or cyclic amides such as N-methyl-pyrrolidone, dimethylacetamide, dimethylformamide, r-butyrolactone, hexamethylphosphoric triamide, and N,N'-dimethyl-ethyleneurea are used. These organic polar solvents can also be used after being diluted with other neutral solvents such as benzene, toluene, cyclohexane, pentane, heptane, methylene chloride, and tetrahydrofuran. Further, it may contain a metal salt such as lithium chloride or calcium chloride.

Of course, this polymer solution can be used directly or concentrated to a desired concentration depending on the case, but in some cases the polymer cake or particles obtained by separating it from the polymer thread can be used as described above. You may use what was redissolved in a solvent.

Although the precipitants listed above are miscible with the solvent of the polymer solution, a liquid or solution that is a non-solvent for the polymer is preferred. For example, water, glycerin, ethylene glycol,
It may be a single liquid or a mixed liquid of alcohol, hydrocarbon, etc. Furthermore, solutions in which metal salts such as lithium chloride, lithium chloride, lithium bromide, and lithium nitrate are dissolved in these non-solvent systems may also be used.

The valve particle manufacturing device can be any device that introduces a polymer solution into a precipitant under high shear force, removes the solvent from the solution, and simultaneously generates a shearing action or beating action, and is equipped with high-speed rotary blades. It is common that there are. For example, a pipe agitation device or a tank-type agitation device with a set of Waring blenders may be used.

The shape of the manufactured valve is reflected in the physical properties of the sheet-like molded product, and must be determined so that it satisfies the physical properties suitable for the paper-like product, but basically it must be determined to have good intertwining with the short fibers to be made. The fiber length of the bulb grains; the degree of fine branching of the QF, ya fibers or thin film ribbons, etc. are must be manufactured under controlled conditions. However, generally, the bulb particle size has a distribution in the range of 24 to 80 meshes as a main component.

Next, when manufacturing a sheet-like product using short fibers manufactured from the aromatic polyamide with a specific structure of the present invention and aromatic polyamide pulp particles, the amounts of the valve particles and short fibers will depend on the target physical properties of the intended use of the sheet to be manufactured. It can be selected arbitrarily, but usually the ratio of bulb particles to short fibers is 20 to 80 wt%.
/80~20wt% preferably 40~60wt%/60
~40wt%. If the amount of bulb particles is less than 20w%, the dielectric breakdown strength, strength and elongation of the paper will deteriorate, and 80w
If it exceeds t%, strength and elongation and impregnation properties will deteriorate.

The sheet is manufactured from a mixed water-dispersed slurry of bulb particles and short yaa fibers using a paper machine similar to that used for making natural bulb paper, such as a fourdrinier or cylinder paper machine.

After drying the obtained wet sheet, a high-quality sheet-like product can be obtained by subjecting it to heating and pressure treatment through a hot press or hot rolls. Short fibers used in papermaking together with valves have a fineness of 0.5 to 10 denier and a length of 1 to 20 denier.
The person who uses fighting things according to [] is the one who uses it. The hot press or hot roll conditions vary somewhat depending on the composition ratio of the bulb and short fibers, the J+7 size of the target sheet, etc., but the temperature is 150 to 450°C, preferably 250°C.
-350 DEG C., the pressure is preferably 50-350 Kg/cm2, preferably 200-300 g/cm'.

[Examples] Next, aspects of the present invention will be illustrated by examples, but the present invention is not limited only by these examples.

Example 1 Preparation of polymer solution [poly(4-methyl-1,3-phenylene terephthalamide)]: 50.5 g (40.03 mol) of terephthalic acid 6fi, 20.50 g of potassium fluoride, N',N-dimethyl −
A mixture of ethylene urea + 61 was heated to 200°C, and 6970.1 g of 2,4-tolylene diisocyanate was added to it.
(40.02 mol) was added in 2 hours. Furthermore, 30
After continuing the reaction for a minute, the mixture was filtered through a 200-mesh wire mesh.

Manufacture of ya fiber: Concentrate the polymer polymerization solution mentioned above to obtain a solid mass of about 12.5w.
A spinning dope of t% was prepared. This stock solution was kept at 50°C, and then subjected to moist heat stretching for about 1 hour in a bath with the same composition as the Lucium chloride coagulation bath maintained at 80°C through a nozzle with a hole diameter of 0.11 mm and 600 holes (each hole was circular). .6 times, and then thoroughly washed with water in a washing bath consisting of 80° C. warm water, followed by applying an oil agent and drying through a hot air bath at 150° C. to obtain a moist heat drawn spun yarn.

The spinning yarn has an oval cross section but is homogeneous and has a diameter of 2900
It was a denier/600 filament.

Next, this spun yarn was subjected to dry heat stretching at a draw ratio of about 2.4 times using a nitrogen flow dry heat drawing machine maintained at 400°C. 3-
phenylene terephthalamide)] fiber was produced.

The physical properties of the obtained fiber were as follows: single yarn denier = 2, strength = 5.
8g/cl, elongation -25.4%, Young's modulus = 88g/
d, Tm (melting point) -125°C, Xc = 24%, Dsr
(Tm) = Dsr (425°C) = 13%, Dsr (T+n+ 55°C) = Dsr (480°C)
= 18%, indicating that the fiber has extremely good dimensional stability even at high temperatures above the melting point.

Manufacture of valve particles: N-methylpyrrolidone solution (solid content: 10
% by weight) to produce valve particles. A 5% by weight aqueous NMP solution was prepared as a precipitant.

Producing the above polymer valve using a pipe agitator equipped with a stator with baffles on the outside and a turbine blade-shaped rotor on the inside, and also equipped with a precipitant, a solution supply port, and a precipitated valve slurry discharge [1] did. 250g/min of the above polymer solution, 2500g of precipitant
The valve slurry thus produced was continuously filtered, and the separated valve cake was washed with distilled water at 80°C. The basic physical properties of the produced valve were as follows.

Average specific filtration resistance: 9 X IQ” (cm/g
), water retention rate = 560% Sieving residual rate = 2.3% remaining on 24 mesh, 29.1% remaining on 48 mesh, 33.7% remaining on 80 mesh, 26.5% remaining on +50 mesh, 8. 4% Production of sheet-like product: A sheet-like product is produced using the valve particles and fibers produced from the above [poly(4-methyl-1,3-phenylene terephthalamide)]. Valve particles (solid content) 800
A water dispersion prepared by mixing 1 m3 of an aqueous polymer containing 400 g of short fibers cut into 7 mm pieces was continuously formed into paper using a 150-mesh inclined mesh, and then dried to obtain a well-formed sheet-like roll. This is introduced between heating rolls at a temperature of 270.
A good sheet was obtained by hot pressing at a temperature of 300 Kg/cm at a linear pressure of 300 Kg/cm. The physical properties of the obtained sheet were as shown in Table 1.

As is clear from the table, the general mechanical properties and dielectric breakdown voltage are good, almost equivalent to those of the PMIA type sheet, and the sheet according to the present invention has significantly better dimensional stability at chilly high temperatures. Recognize.

Example 2 Preparation of polymer solution: Poly(4-chloro-1,3-phenylene terephthalamide) was prepared using the same equipment as in Example 1.

Terephthalic acid chloride 200.5 g (0,9875
mole), N,N'-dimethyl-ethyleneurea (hereinafter DM
1500 mJZ (abbreviated as r) was added, dissolved at 100°C, and while maintaining the contents at this temperature, from the dropping funnel, 1=chloro-2,4-phenylenediamine 251.5
g (0,9875 mol) to 150ml! A solution dissolved in DMI was added for about 10 minutes. Thereafter, the reaction was continued for about 1 hour while suctioning from the top of the condenser to a reduced pressure of 100 m+n11 g. It was then cooled to room temperature.

A portion of the obtained polymerization liquid was taken and treated in the same manner as in Example 1. The logarithmic viscosity of the obtained polymer was 1.5. The polymer concentration of this polymerization solution was about 12.5% by weight, and the viscosity of this solution was 450 voids (B-type viscometer: 50° C.).

Manufacturing of fibers: Fibers were produced under the same conditions as in Example 1.

Fiber performance: M yarn denier = 2, strength 5.3 g/d, elongation 28%,
Young's modulus = 90g/d, Tm = 420°C, T
ex = 340°C, Tm-Tcx = 80°C, Xc = 25
%, Dsr (T+++) = Dsr (425°C) = 12
%, indicating good general fiber physical properties, a strong shape at high temperatures above the melting point, and hood stability.

Production of valve particles: Poly(metaphenylene-isophthalic-terephthalamide) was mixed with meta-phenylenediamine and isophthalic acid chloride/terephthalic acid chloride (
50150 mixture). Bulb particles were produced in the same manner as in Example 1.

The basic physical properties of the obtained valve particles were as follows.

Tg: 295℃ Average specific filtration resistance: 8.5 x 10' (cm/
g), water retention: 520%, residual 34.2%, +50 mesh residual 28.0%, 150 mesh passing 4.0% Production of sheet-like product: Paper was made under the same conditions as Example 1 to produce a sheet-like product. Obtained. The physical properties of the obtained sheet were as shown in Table 1.

As is clear from the table, the general mechanical properties and dielectric breakdown voltage are good, almost equivalent to those of the PMIA type sheet, and the sheet according to the present invention has significantly better dimensional stability at high temperatures. Recognize.

Comparative Example 1 Production of poly(metaphenylene isophthalamide): 250.2 g (1,232 mol) of isophthalic acid chloride, anhydrous tetrahydrofuran in 21 jacketed separable flasks equipped with a stirrer, a thermometer, and a jacketed dropping funnel. 600 m11. was charged and dissolved, and the contents were cooled to 20°C by passing a refrigerant through the jacket. 133.7 g (1°237 mol) of metaphelene diamine was added to 400 ml of anhydrous tetrahydrofuran with strong stirring.
was added dropwise over about 20 minutes. The resulting white emulsion was added to water containing 2.464 mol of anhydrous soda (water-cooled).
The mixture was quickly poured into the container while stirring vigorously. Immediately, the slurry temperature rose to near high temperature. Followed by caustic soda pl
After adjusting the + to 11, the slurry was filtered, and the resulting cake was thoroughly washed with % j, i of water.
The logarithmic viscosity of the polymer obtained by drying overnight under reduced pressure at 0° C. was 1.4.

Manufacture of poly(metaphenylene isophthalamide) fiber: The poly(metaphenylene isophthalamide), namely PMIA polymer powder, was mixed with N-methyl-2-pyrrolidone (NMP) and 2% LiC1 based on NMP. It was dissolved in the containing solvent at a concentration of 22% by weight and degassed under reduced pressure at 80°C to prepare a spinning stock solution containing no air bubbles. Then, while maintaining the temperature at 80°C, CaCl2 was injected from a nozzle with a hole diameter of 0.08 mm and a number of holes of 100 (outer holes are circular).
It was discharged at 5.2 g/min into an aqueous coagulation bath containing 40%, passed through a roller rotating at IOm/min, passed through an 80°C hot water bath, and rinsed thoroughly with water. Moist heat stretching was carried out using rollers at a ratio of 2.88 times, and after applying an oil agent, the fibers were dried by passing through a hot air tank at 150° C. to obtain a wet heat drawn spun yarn. The spun yarn had a homogeneous cocoon-shaped cross section and was 358 denier/100 filaments.

Next, this spun yarn was subjected to dry heat stretching 1.88 times on a plate at 310°C to obtain poly(metaphenylene isophthalamide>tpa fibers).

The physical properties of the obtained fibers are: single yarn denier = 2, strength 4.9
g/d, elongation = 28.5%, Young's modulus = 80g/d
, Tg=280℃, Tm=425℃, Tex=405℃
, Tm-Tex=20℃, Xc=25%, Dsr(T
m) = Dsr (425° C.) = 16%, and although this PMIA fiber, which is outside the scope of the present invention, exhibits good general fiber physical properties, the shape stability at high temperatures above the melting point of Example 1, which is outside the scope of the present invention. , which was clearly inferior to Example 2.

Production of valve particles: The valve particles produced in Example 1 using the above PMIA were used.

Manufacture of a sheet-like product: A sheet-like product was obtained by making paper using the same dye as in Example 1 using the short fibers and bulb particles produced from PMIA described above.

The physical properties of the obtained sheet were as shown in Table 1.

At high temperatures of 280°C or higher, dimensional changes in the sheet were noticeable, and particularly after 450°C IO minutes, the sheet significantly shrank while being cured as a whole, and lost its supple sheet state.

Table 1 Kuraray Co., Ltd.

Claims (2)

[Claims] (1) Tm≧350℃, Tm-Tex≧30℃, Xc≧
10%, De≧10%, Dsr(Tm)≦15%, and Dsr(Tm+55°C)/Dsr(Tm)≦3 [where Tm: melting point (°C), Tex: exothermic onset temperature (°C), Xc
: Crystallinity (%), De: Fiber elongation (%), Dsr (T
i): Dry heat shrinkage rate (%) at melting point, Dsr (Tm+
55°C): represents the dry heat shrinkage rate (%) at melting point + 55°C. ] A heat-resistant sheet material having excellent high-temperature dimensional stability obtained by mixing aromatic polyamide short fibers and aromatic polyamide pulp particles to form a paper, followed by heating and pressing. (2) The short fiber is selected from a lower alkyl group having 1 to 4 carbon atoms, an amino group, a sulfone group, a carboxyl group, and a hydroxyl group in the ortho position of the phenylene group directly connected to the nitrogen atom and/or carbon atom of the amide bond. The heat-resistant sheet material according to claim 1, which is a short fiber made of aromatic polyamide having a functional group or a halogen atom.