JPS627227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin reinforced with potassium titanate fibers, and more particularly to a fiber-reinforced resin characterized in that the fiber surface is coated with a metal oxide film for preventing elution of alkali ions.

The purpose of the present invention is to provide potassium titanate fibers that prevent the 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.

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 modulus of elasticity, and electrical conductivity, but it has the same drawbacks as glass fiber, such as anisotropy and surface roughness, and is extremely expensive. It can only be used for specific purposes. 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 for use in reinforcing resins. Potassium titanate fibers are characterized by their extremely small fiber size and relatively long fiber length. Teismo-D is a representative example.
(Product name: Otsuka Chemical Co., Ltd.) has a fiber diameter of 0.2 to 0.5.
μm, average fiber length of 10 to 20 μm, and a high aspect ratio (fiber diameter/fiber length). In addition, regarding mechanical strength, tensile strength is 700Kg/mm2 ^or more, and elastic modulus is 28000.
It is estimated to be over Kg/mm ² . Heat resistance and melting point
Very high temperature 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, the strength and dimensional anisotropy are relatively small, and the surface smoothness is also good. Also, when molded into small articles, the fluidity of filling into minute parts is better than that of other reinforcing fibers. Although this reinforcing fiber is relatively well-balanced, its applications are limited. As mentioned above, potassium titanate fiber is represented by the general formula K ₂ O.nTiO ₂ , but the constituent element potassium (k) is slightly leached. For example, when potassium titanate is dispersed in water, the hydrogen ion concentration (PH) of the water is 7 to 9, making it slightly alkaline. 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 present invention was achieved as a result of intensive research aimed at improving the above-mentioned drawbacks of potassium titanate fibers.

In other words, the present invention coats the surface of potassium titanate fibers with a dense metal oxide film to prevent the diffusion and elution of potassium, and then further performs a silane coupling treatment on the film. This completely solves the disadvantages of fibers. Various methods are used to coat a solid surface with a metal oxide film. For example, physical methods in vacuum such as vapor deposition, sputtering, and ion plating are common. It is extremely difficult to form a metal oxide film on ultrafine acicular 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.
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 can be synthesized through dealcoholization through hydrolysis reactions and dehydration condensation reactions through thermal decomposition reactions. Produces metal oxides.

M(OR)n+nH ₂ O→M(OH)n+nROH (1) M(OH)n→MOn+nH ₂ O (2) M: Metal element Metal alcoholates are usually dissolved in an organic solvent at an appropriate concentration and used as a processing solution. Ru. The treatment method is to immerse the article in a solution, pull it up, heat dry it, immerse it in the solution, evaporate only the solvent, and then spray apply the solution to 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 tetraisobutoxysilane; 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 and ethanol isopropanol, ketones such as acetone methyl ethyl ketone and methyl isobutyl ketone, esters such as methyl acetate and ethyl acetate, polyhydric alcohols, aromatic solvents, etc. used alone or in a mixed state. I can do it. In addition to the above-mentioned components, various catalysts for promoting the reaction may also be used as treatment liquid components.
For example, organic carboxylic acids such as formic acid and acetic acid, hydrochloric acid,
These include inorganic acids such as sulfuric acid, nitric acid, and phosphoric acid, and metal chlorides such as tin chloride and aluminum chloride. Various concentrations are used for the treatment solution depending on the treatment method, but generally the metal alcoholate content is
0.1wt%~50wt%, preferably 0.5wt%~20wt
% range. If it is less than 0.1wt%, the film thickness after reaction will be thin and the effect of preventing 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 preferably 100°C to 600°C. If it is below 50°C, a dense film cannot be obtained, and if it is above 800°C, potassium ions will thermally diffuse into the film from the potassium titanate fiber matrix, weakening the effectiveness of the treatment. The thickness of the metal oxide film obtained in this way is 100 Å to 1 μm, preferably 300 Å to
Used in the 0.2 μm range.

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.

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: Tetramethoxysilane 200ml Acetic acid 10ml Isopropyl alcohol 2 Immersed at room temperature for 5 minutes, and excess treatment solution was drained. After separation, the treated product was heat-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
Pellets were prepared by blending 20 wt% of polycarbonate (Pan Light Tray 1225L, Teijin Kasei Ltd.) using Ikegai Tekko Co., Ltd.). The pellets had a white appearance and were obtained in a glossy state. When the molecular weight of unused polycarbonate was measured by solution viscosity method, M=
Compared to 22,300, 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 γ-glycidoxypropyltrimethoxysilane (SH6040 manufactured by Toray Silicone) was added to potassium titanate fibers treated in the same manner as in Example 1.
A solution of 1.0 wt% isopropanol + 0.1 wt% acetic acid was sprayed on the surface of the sample and dried at 130°C for 1 hour. 2 processed items
Pellets containing 30 wt % of polycarbonate (L-1225L) were prepared using a axial kneading extruder (PCM-30). The bending strength of this material is 1850Kg/ ^cm2 ,
The bending strength of the material obtained in Example 1 was improved to 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.

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.
Further, since a metal oxide film is obtained by the decomposition reaction of the metal alcoholate, it is easy to manufacture and can be processed in large quantities, making it suitable for mass production. Moreover, a metal oxide film having a uniform thickness and good adhesion properties can be obtained.
Furthermore, since the metal oxide film is an insulator, it can also be applied to IC molding materials that require insulation. Moreover, the optimum combination of the metal oxide film and the silane coupling treatment produces the maximum effect and has the effect of further improving the mechanical strength of the resin.

Claims (1)

[Claims] 1. In a fiber-reinforced resin reinforced with potassium titanate fibers, the surface of the potassium titanate fibers is coated with a metal oxide film formed by a thermal decomposition reaction after hydrolyzing a metal alcoholate,
The fiber-reinforced resin is further characterized by being subjected to silane coupling treatment.