JPH0129813B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a resin reinforced with potassium titanate fibers, and is particularly characterized in that the fiber surface is coated with a metal oxide film that prevents the elution of alkali ions. The present invention relates to a method for producing fiber reinforced resin.

[Conventional technology]

Traditionally, a typical method for improving the strength of resins has been to fill them with reinforcing fibers such as glass fibers, carbon fibers, mica, alumina fibers, silicon carbide fibers, aromatic nylon fibers, etc., either singly or in combination. . Among them, glass fiber is used in various fields because of its low price and relatively high reinforcement efficiency. However, when glass fibers are dispersed in a resin, there are many disadvantages such as decreased fluidity, increased anisotropy in strength and shrinkage, roughened surfaces of molded products, and increased wear on processing machines and molds. On the other hand, carbon fiber can be expected to have improved properties such as low friction and wear, high elastic modulus, and electrical conductivity, but it has the same drawbacks as glass fiber, such as anisotropy and surface roughness, and its price limits its use. It can only be used. Other reinforcing materials also have advantages and disadvantages in terms of physical properties and cost, making it difficult to expand their use. Potassium titanate fibers can be used to improve the drawbacks of each reinforcing fiber. Potassium titanate fibers are represented by the general formula K ₂ O.nTiO ₂ , and various types with different n have been synthesized. Among them, the representative compound is K ₂ O.bTiO _{2 ,} which is currently being investigated as a material for reinforcing resins.

As a known example, as seen in JP-A-43-8936, potassium titanate fibers are prepared in a slurry obtained by hydrolyzing metal oxides, sulfates, halides, nitrates, aluminates, and zircolates. There is a description to process it. However, these methods require large-scale equipment or are difficult to uniformly distribute the hydrolyzed slurry over the potassium titanate fibers.

Also, as seen in Japanese Patent Application Laid-open No. 43-38792,
Although there is a description of using alcoholate titanate for glass fibers, there is no description that it can be applied to materials from which alkali easily elutes, such as potassium titanate fibers.

Potassium titanate fibers are characterized by their extremely small fiber size and relatively long fiber length. A typical example is Teismo D (trade name, manufactured by Otsuka Chemical Co., Ltd.), which has a fiber diameter of 0.2 to 0.5 μm and an average fiber length of 10.
It has a high aspect ratio (fiber diameter/fiber length) of ~20 μm. Also, regarding mechanical strength, tensile strength is 700
It is estimated that the elastic modulus is more than Kg/mm ² and the elastic modulus is more than 28000 Kg/mm ² . It also has very high heat resistance, with a melting point of 1300-1350℃. On the other hand, the price is almost the same as that of engineering plastics, and the price increase due to compounding is generally within an acceptable range. When a resin reinforced with such potassium titanate fibers is made into a molded product, its strength and dimensional anisotropy are relatively small.
Good surface smoothness. Also, when molded into small articles, the fluidity of filling into minute parts is better than that of other reinforcing fibers.

[Problem that the invention seeks to solve]

However, although it is a relatively well-balanced reinforcing fiber, its applications are limited. As mentioned above, potassium titanate fiber has the general formula K ₂ O.
Potassium (K), which is a constituent element of nTiO ₂ , is slightly leached. For example, when potassium titanate is decomposed in water, the hydrogen ion concentration (PH) of the water becomes weakly alkaline at 7 to 9. This property prevents the compounding of potassium titanate fibers into resins that are easily hydrolyzed. Furthermore, resins containing potassium titanate fibers are difficult to apply to applications where ionic impurities are a concern.

The purpose of the present invention is to provide potassium titanate fibers that prevent elution of alkali ions at a low cost, so that the fibers can be applied to all kinds of resins, especially resins that easily cause decomposition reactions with alkali ions. It is possible.

Another object of the present invention is to enable the above-described potassium titanate fibers of the present invention to be incorporated into resins that require high electrical insulation.

[Means for solving problems]

The method for producing a fiber-reinforced resin of the present invention includes the steps of: wetting the potassium titanate fibers with a solution obtained by hydrolyzing metal alcoholate; and titanic acid wetted with the solution. a step of separating the potassium fibers by filtration; a step of heating and drying the filtered potassium titanate fibers to form a metal oxide on the surface; and a step of applying a silane cup to the surface of the potassium titanate fibers on which the metal oxides have been formed. The method is characterized by comprising a step of forming a ring agent.

In other words, the present invention coats the surface of potassium titanate fibers with a dense metal oxide film to prevent potassium from spreading and eluting, and then further performs a silane coupling treatment on the film to coat the surface of the potassium titanate fibers. It completely solves the drawbacks of having potassium fiber. Various methods are used to coat a solid surface with a metal oxide film. For example, vapor deposition,
Physical methods in vacuum such as sputtering and ion plating are common. It is extremely difficult to form a metal oxide film on extremely fine needle-like powder such as potassium titanate fibers using the above method. The present invention is characterized in that a metal oxide film is formed by a decomposition reaction of a metal alcoholate. Metal alcoholates were used because of their easy availability, stability of decomposition products, ease of forming into thin films, advantages in formation when combined with other metals, and uniform dispersibility. . Various types of metal alcoholates can be synthesized at room temperature, from low viscosity liquids to sticky liquids, and as shown in equations (1) and (2), they are synthesized through dealcoholization through hydrolysis reactions and dehydration condensation reactions through thermal decomposition reactions. Produces metal oxides.

M.(OR)n+nH ₂ O→M(OT)n+nROH (1) M(OH)n→MOn+nH ₂ O (2) M: Metal element Metal alcoholate is usually dissolved in an organic solvent at an appropriate concentration and used as a processing solution. be done. The processing method is to immerse the item in a solution and then pull it up and heat dry it, immerse it in the solution and evaporate only the solvent and then heat dry it, or spray coat the solution and then heat dry it.

Various mass-production methods can be selected, such as spray coating on a heated workpiece or treating a heated workpiece in metal alcoholate vapor.

Any metal alcoholate can be used in the present invention as long as it forms an oxide film through a decomposition reaction. Typical compounds include tetraalkyloxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetrasoptoxysilane; tetraalkyloxytitaniums such as tetrapropoxytitanium, tetraptoxytitanium, and tetra-2-ethylhexyltitanium; and tetraalkyl. Examples include oxytins, tetraalkyloxyzirconiums, and trialkyloxyindiums. They may be used alone or in a mixed state. Organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone methyl ethyl ketone and methyl isobutyl ketone, esters such as methyl acetate and ethyl acetate, polyhydric alcohols, and aromatic solvents, either alone or in a mixed state. It can be used. In addition to the above-mentioned components, various catalysts for promoting the reaction may also be used as treatment liquid components. Examples include organic carboxylic acids such as formic acid and acetic acid, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and metal chlorides such as tin chloride and aluminum chloride. The concentration of the treatment liquid varies depending on the treatment method, but generally the metal alcoholate content is 0.1 wt% to 50 wt%, preferably 0.5 to 50 wt%.
It is in the range of 20wt%. If it is less than 0.1wt%, the film thickness after the reaction will be thin and the effect of preventing the elution of alkali ions will be small, and if it is more than 50wt%, the film will become too thick and cracks will occur and the treatment effect will be lost. The heating temperature is not particularly limited as long as it is within the melting point of potassium titanate, but it is generally within the range of 50°C to 800°C and is preferably 100°C to 600°C. 50
If the temperature is below 800℃, a dense film cannot be obtained.
℃ or higher, potassium ions from the potassium titanate fiber matrix will thermally diffuse into the film, weakening the effect of the treatment. The thickness of the metal oxide film obtained in this way is 100 Å to 1 μm, preferably 300 Å to 1 μm.
It is used in the range of Å to 0.2 μm.

The potassium titanate fibers treated by the above method can be subjected to a coupling treatment using a known silane coupling agent or the like to improve wettability with resin. The thickness of the coupling film is generally from the monomolecular layer level to about 500 Å, but is not limited to this range.

〔Example〕

The present invention will be further explained below with reference to Examples.

Example 1 1 kg of potassium titanate fiber Teismo D (Otsuka Chemical Co., Ltd.) was stirred into a treatment solution with the following composition: 200 ml of tetramethoxysilane, 10 ml of acetic acid, 10 ml of isopropyl alcohol 2. Soaked at room temperature for 5 minutes, and excess treatment solution was filtered. Separated, the treated product was heated and dried in a closed container with hot air at 80°C while stirring. Thereafter, it was baked at 500°C for 1 hour in a stationary state. This fiber is processed using a twin-screw kneading extruder (PCM-
30 Ikegai Steel Co., Ltd.) was used to prepare pellets containing 20 wt% of polycarbonate (Panlite Tray 1225L Teijin Kasei Co., Ltd.). The pellets had a white appearance and were obtained in a glossy state. When the molecular weight was measured by solution viscosity method, unused polycarbonate was M
= 22,300, whereas the pellet had M = 21,600, and there was no significant decrease in molecular weight.

Example 2 While stirring 1 kg of potassium titanate fiber TEISMO D, a treatment solution having the following composition was sprayed in its entirety.

Tetramethoxysilane 100ml Tetrabutoxytitanium 20ml Trichlorotrifluoroethane 1 The mixture was then calcined at 400°C for 2 hours. A pellet containing 30 wt % of this fiber in polycarbonate was prepared in the same manner as in Example 1, but the pellet had no abnormal appearance and molecular weight.

Comparative Example 1 Pellets containing potassium titanate fiber Teismo D at 20 wt % with respect to polycarbonate were prepared in the same manner as in Example 1 without any surface treatment.
The pellets had a dark yellowish-white appearance and a rough surface. When the molecular weight was measured, it was found that the unused polycarbonate had M=22,600, whereas the pellet had M=12,400, which was an extremely low molecular weight.

Example 3 Potassium titanate fibers treated in the same manner as in Example 1 were further treated with γ-glycidoxypropyltrimethoxysilane (SH6040 manufactured by Toray Silicone).
A 1.0 wt% isopropanol + 0.1 wt% acetic acid solution was sprayed and dried at 130°C for 1 hour. The treated product was blended with polycarbonate (L-1225L) at 30 wt% using a twin-screw extruder (PCM-30) to produce pellets. The bending strength of this material was 1850 Kg/cm ² , which was higher than the strength of the material obtained in Example 1, which was 1620 Kg/cm ² , and it was confirmed that the reinforcement efficiency was improved by the coupling treatment. The bending strength of polycarbonate alone was 910Kg/ ^cm2 .

Although some specific examples of the present invention have been described in the above embodiments,
The type of metal alcoholate, the composition of the treatment liquid, the resin to which the treatment method is applied, etc. are not limited to the scope of the examples.

〔Effect of the invention〕

The present invention has made it possible to incorporate potassium titanate fibers into any resin. In particular, it can be blended with resins that are easily hydrolyzed, such as polycarbonate, without deteriorating physical properties, and can be applied to exterior parts where molded appearance is important, such as watch cases, camera cases, VTR cases, etc. It can also be applied to fields that require high dimensional accuracy.

Claims (1)

[Claims] 1. A method for producing a fiber-reinforced resin using potassium titanate fibers, comprising: wetting the potassium titanate fibers with a solution obtained by hydrolyzing metal alcoholate; and filtering the potassium titanate fibers wetted with the solution. separating the potassium titanate fibers by heating and drying the filtered potassium titanate fibers to form a metal oxide on the surface; and forming a silane coupling agent on the surface of the potassium titanate fibers on which the metal oxides have been formed. A method for producing a fiber-reinforced resin, comprising the steps of: