JPH04261437A - Heat-resistant polyacrylonitrile composite film or fiber - Google Patents

Abstract

PURPOSE:To provide an acrylonitrile film or fiber having excellent heat- resistance and high-temperature dimensional stability and extremely useful as industrial materials, etc. CONSTITUTION:The objective heat-resistant polyacrylonitrile composite film or fiber is composed of a composite of (A) an acrylonitrile polymer having an acrylonitrile content of >=70wt.% and (B) 1-70wt.% (based on the polymer) of a metal oxide derived from a metal alkoxide. The lowering ratio of the elastic modulus at the tandelta peak temperature based on the modulus at 25 deg.C is <=70% by dynamic viscoelasticity measurement. The thermal decomposition initiation temperature of the above composite material is higher than that of the non-composite acrylonitrile fiber by >=10 deg.C.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to films and fibers made of a composite of an acrylonitrile composite and a metal oxide, which have excellent heat resistance and dimensional stability.

0002

[Prior Art] Acrylonitrile copolymers, which have excellent weather resistance and dyeability, are widely used in fibers, films, etc.; Sex is strongly desired. In order to meet this demand, it is generally known that Si02 fine particles are dispersed or inorganic fillers are dispersed. In addition, as a composite using a metal alkoxide, a transparent heat-resistant composition consisting of a composite of a metal alkoxide and a polysiloxane containing a terminal silanol group (Japanese Patent Application Laid-Open No. 2-10222
No. 9) etc. are known.

However, even when an inorganic filler is added to an acronitrile polymer, there are not many examples in which the heat resistance is improved. Furthermore, when adding SiO2, TiO2, etc., it is difficult to add and disperse large amounts. Moreover, in this case, it is only in a dispersed state, and addition causes a decrease in physical properties such as strength of the polymer.

0004

[Problems to be Solved by the Invention] The present inventors have discovered that SiO
2. Eliminates the drawbacks of conventional methods of increasing the heat resistance of acronitrile polymers by adding TiO2, etc. or inorganic fillers, and improves heat resistance without causing a decrease in physical properties such as strength of the polymer. An object of the present invention is to provide a film or fiber composed of a composite of an acrylonitrile polymer and a metal oxide.

[0005]

[Means for Solving the Problems] That is, the present invention consists of a composite of an acrylonitrile polymer containing 70% by weight or more of acrylonitrile and a metal oxide from a metal alkoxide in an amount of 1 to 70% by weight of the polymer. The present invention is a heat-resistant acrylonitrile-based composite film or fiber, characterized in that the reduction rate of the elastic modulus at tan δ peak temperature with respect to the elastic modulus at 25° C. in dynamic viscoelasticity measurement is 50% or less.

The present invention also provides a film or fiber comprising an acrylonitrile polymer composite whose thermal decomposition initiation temperature is 10° C. or more higher than the thermal decomposition initiation temperature of the acrylonitrile polymer that does not form the composite. be.

The metal alkoxide used to form the acrylonitrile polymer complex in the present invention can be synthesized by known synthesis methods, such as a method in which a metal and an alcohol are directly reacted using mercury chloride as a catalyst, or a method in which a metal chloride and an alcohol are directly reacted. It can be produced by various methods such as a method of reacting alcohols, or, when direct synthesis is difficult, a method of synthesis by exchanging alcohols. Further, as the metal, any metal can be used as long as an alkoxide can be synthesized by these methods, but silicon, aluminum, titanium, zirconium, and mixtures thereof are preferable.

[0008] Furthermore, the acrylonitrile polymer used to form the acrylonitrile polymer composite in the present invention must have an acrylonitrile content of 70% by weight or more, and if it is less than 70% by weight, the acrylonitrile The properties of the polymer are lost and the desired composite cannot be obtained. Examples of components that can be copolymerized with acrylonitrile include methyl methacrylate and ethyl methacrylate.
Methacrylic acid esters such as methacrylate, butyl methacrylate, hexyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, fluoroalkyl acrylate, etc. : Vinyl halides such as vinyl chloride, vinyl bromide, vinylidene chloride, etc.: Methacrylic acid, acrylic acid,
Acids such as itaconic acid, crotonic acid, vinyl sulfonic acid and their salts: maleic acid imide, phenylmaleimide, acrylamide, methacrylamide, styrene, α
-Methylstyrene, vinyl acetate, etc., and mixtures thereof may also be used.

In order to form a composite of an acrylonitrile polymer and a metal oxide derived from a metal alkoxide in the present invention, the acrylonitrile polymer is homogeneously dissolved in a solvent to form a solution, and the metal alkoxide is added to the acrylonitrile polymer. It is preferable to adopt a method of mixing, then hydrolyzing the metal alkoxide and causing a polycondensation reaction to form a composite of the acrylonitrile polymer and the metal oxide. The mixing ratio of these acrylonitrile polymers and metal alkoxides is as follows:
1% by weight or more, preferably 10% by weight or more, based on the acrylonitrile polymer as the metal oxide after hydrolysis, 7
This is the ratio necessary to contain 0% by weight or less. If the content of metal oxide after hydrolysis is less than 1% by weight,
If the heat resistance effect does not appear and the amount exceeds 70% by weight, the physical properties of the acrylonitrile-based composite will deteriorate, for example, flexibility will be lost.

[0010] Any solvent may be used to form the above-mentioned complex as long as it dissolves the acrylonitrile polymer and also dissolves the metal alkoxide, such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, γ- Examples include butyrolactone and ethylene carbonate. Further, in forming this composite, it is preferable to use an appropriate amount of water for hydrolyzing the metal alkoxide, and an acid or base as a catalyst.

Various methods can be used to form a film or fiber composed of a composite of an acrylonitrile polymer and a metal oxide derived from a metal alkoxide. For example, a film can be formed by adding a metal alkoxide to an acrylonitrile polymer solution, casting the solution in which the metal alkoxide is reacted, and evaporating the solvent. In addition, from the above reaction solution with an appropriate viscosity, dry method,
Fibers can be formed by wet or dry-wet spinning.

The composite of the acrylonitrile polymer and the metal oxide derived from the metal alkoxide in the present invention has a network of the metal oxide intertwined with the polymer molecular chain, and is a molecularly dispersed composite. It has become a body. Films or fibers made of this composite exhibit a reduction rate of 70% or less in the elastic modulus at the Tan δ peak temperature in dynamic viscoelasticity measurements compared to the elastic modulus at 25°C, and even at high temperatures. It has the property of ensuring elastic modulus.

[0013] Furthermore, the composite of the acrylonitrile polymer and the metal oxide derived from the metal alkoxide in the present invention has a thermal decomposition initiation temperature (weight loss initiation temperature) of 10°C or more compared to the original acrylonitrile polymer. It has high heat resistance.

Further, preferred embodiments of the present invention are as follows. 1. The heat-resistant acrylonitrile composite film or fiber according to claim 1 or 2, wherein the metal oxide component is contained in an amount of 10% by weight or more based on the acrylonitrile polymer. 2. The metal of metal alkoxide is silicon, aluminum,
Claim 1, Claim 2, or 1 above, which is one or more metals selected from the group consisting of titanium and zirconium.
The heat-resistant acrylonitrile composite film or fiber described above.

[0015]

[Example] Next, an example of the present invention will be shown. The dynamic viscoelasticity in each example was measured under the following conditions. Measuring device: Orientec Leovibron DDV-
2 Measurement conditions Measurement frequency 110Hz Heating rate
2° C./min Furthermore, in each Example, the weight loss onset temperature of the film or fiber in nitrogen was measured by TG-DTA (thermogravimetry-differential thermal analysis) under the following conditions. Measuring device TG-DTA measuring device manufactured by Rigaku Denki Co., Ltd. Measuring conditions Sample amount 10 mg Heating rate 10° C./min The exothermic peak temperature observed at the start of weight loss was defined as thermal decomposition start temperature (TD).

Example 1 4 g of tetraethoxysilane [Si(OC2H5)4],
4 g of polyacrylonitrile (molecular weight 400,000),
Dimethylformamide 46g, water 0.35g, hydrochloric acid (3
(containing 5%) was heated at 80° C. for 2 hours to cause a heating reaction of tetraethoxysilane. The solution after this reaction was cast onto a glass plate and vacuum dried at 80° C. for 24 hours. The obtained cast film had a thickness of 30 μm. In addition, the above polyacrylonitrile (molecular weight 400,000
A cast film having a thickness of 27 μm consisting only of 0) was similarly obtained by the solvent evaporation method.

The thermal decomposition start temperature TD of these films is as follows:
It was as follows. Polyacrylonitrile film TD=275°C Polyacrylonitrile composite film TD=300°C Also, the dynamic viscoelasticity E' at each temperature was as follows. E' at 25°C = 8 x 1010 dyn/cm2 Tan δ peak temperature at 110°C E' = 6.8 x 1010 dyn/c
m2 Therefore, the elastic modulus reduction rate was 15%.

Example 2 Tetra-n-butoxytitanium (Ti(OC4H9)4)
5 parts, 93% by weight of acrylonitrile and methyl acrylate
Copolymer consisting of 7% by weight (molecular weight 200,000
) 20 parts, water 0.5 part, hydrochloric acid (containing 35%) 0.1 part,
80 parts of dimethylacetamide was reacted at 80° C. for 2 hours, and the reaction solution was made into fibers by wet spinning. Further, the above copolymer was dissolved in dimethylacetamide, and fibers were obtained by wet spinning in the same manner.

The TG-DTA of each of these fibers was measured to determine the thermal decomposition onset temperature TD. Unreacted fiber TD=270
°C Composite fiber TD = 310 °C The dynamic viscoelasticity of the composite fiber was also measured. E' at 25℃=2.0×1010dyn/cm2Tan
E' at δ peak temperature 107°C = 1.7 x 1010 dyn
/cm2 Therefore, the elastic modulus reduction rate was 17%.

Comparative Example 1 20 parts of a copolymer (molecular weight 150,000) consisting of 95% by weight of acrylonitrile and 5% by weight of vinyl acetate, 0.4 part of silica (SiO2) fine particles with an average particle size of 1.1 μm,
A mixture of 80 parts of dimethylacetamide was heated and stirred at 80° C. for 2 hours to prepare a cast film. This cast film had a thickness of 32 μm.

The TG-TDA of this composite film and a cast film (27 μm) without silica was measured, and the thermal decomposition onset temperature TD was measured. Silica-free film TD = 272°C Silica-containing film TD = 273°C The dynamic viscoelasticity of the composite film was also measured. E' at 25℃=5.3×1010dyn/cm2Tan
E' at δ peak temperature 106℃=8.0×109dyn/
cm2 Therefore, the elastic modulus reduction rate was 85%.

Comparative Example 2 A mixture was prepared in the same manner as in Comparative Example 1 except that the amount of silica particles was changed to 2 parts, and the mixture was heated and stirred at 80° C. for 2 hours to form a cast film. This cast film is 3
Although the film thickness was 5 μm, the silica was not homogeneously dispersed.
Only a film with low strength and many spots was produced. The thermal decomposition onset temperature (TD) of this film was measured at 274°C.
Met. In addition, the film was brittle and dynamic viscoelasticity could not be measured.

(Effects of the Invention) A composite of the acrylonitrile-based polymer of the present invention and a metal oxide derived from a metal alkoxide has an elastic modulus of tan δ peak temperature of 25° C. in dynamic viscoelasticity measurement. Heat-resistant acrylonitrile polymer films or fibers with a reduction rate of 70% or less have extremely superior heat resistance and high-temperature dimensional stability compared to conventional organic fibers, and are extremely useful for applications such as industrial materials. It is.

Claims (2)

[Claims] Claim 1: Comprised of a composite of an acrylonitrile polymer containing 70% by weight or more of acrylonitrile and a metal oxide from a metal alkoxide of 1 to 70% by weight of the polymer, tan δ in dynamic viscoelasticity measurement. A heat-resistant acrylonitrile-based composite film or fiber, characterized in that the rate of decrease in the elastic modulus at peak temperature relative to the elastic modulus at 25°C is 70% or less. 2. The heat-resistant acrylonitrile composite film according to claim 1, wherein the thermal decomposition initiation temperature of the acrylonitrile polymer composite is 10° C. or more higher than the thermal decomposition initiation temperature of the non-composite acrylonitrile polymer; fiber.