JPS61283629A - Plastic composite material - Google Patents

Abstract

PURPOSE:To obtain a plastic composite material to which antistatic property, selective transmission of light, light interference, etc., are imparted, by forming a transparent film of a titania hydrosol-based coating composition on the surface of a plastic. CONSTITUTION:A plastic composite material prepared by foaming a transparent film of a titania hydrosol-based coating composition on the surface of a plastic. Especially, when the titania hydrosol is reduced in a sol particle diameter so that its mean diameter may be 0.1mu or below, preferably, 0.05mu or below, the sol component in the titania hydrosol can show a strong affinity for the plastic surface and excellent adhesion and can form a homogeneous titania thin film. In order to obtain a titania hydrosol in the form of fine particles, a process comprising hydrolyzing an aqueous solution of a titanate, preferably, titanium tetraalkoxide in the presence of a stabilizer such as a chelating agent such as acetic acid by using an OH-form anion exchange resin can be advantageously carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a composite material in which an inorganic film is formed on the surface of plastic. Specifically, the present invention relates to a glass composite material in which a strong and transparent film is formed on a plastic surface using a coating composition containing titania hydrosol as a main component. This plastic composite material provides plastic with antistatic properties, selective light transmittance, antifogging properties, light interference properties, heat resistance, chemical resistance, and functions as an immune carrier in the biomedical field. By compounding the titania hydrosol with other metals to form a coating film, it is possible to give plastics more advanced functions, such as conductivity, piezoelectricity, dielectricity, and other functions as sensor materials or photocatalysts. ,
It will also be of industrial significance.

<Conventional technology> Plastic is a material that has excellent features such as being lightweight, easy to process, can be colored freely, and is removable, but on the other hand, it is easily charged with static electricity, has a soft surface that is easily scratched, and has poor chemical resistance. There are also disadvantages.

Particularly in the case of transparent plastics, surface treatment using cyblastic has been conventionally used to compensate for these drawbacks, but depending on the treatment method, the original transparency of the plastic can be easily lost, which can be a serious problem depending on the application. becomes. On the other hand, various surface treatment methods are being studied to improve the functionality of plastics, and it has been proposed to form an oxide-based inorganic coating film with desired properties on the plastic surface ( For example, Japanese Patent Publication No. 1982-21336 ``Method for Forming Cured Film'', JP-A-59-
No. 152850 "Transparent plate for windows", JP-A-59-8393
No. 5 "Processing method for titanium oxide film", JP-A-59-213
No. 603, ``Method for producing thin film-like composite materials,'' various publications and Kagaku Kogyo, July 1984 issue, P581-584, ``Coating by sol-gel method,'' Mr. Masao Sakuhana). However, all of these conventionally known coating films use organic metal compounds, especially metal alkoxides, and generally when they are applied to plastic surfaces, the film becomes cloudy or powdery when dried. There was a problem that it easily peeled off and fell off the substrate.

Other methods include applying chelates such as metal acetylacetonate, organometallic compounds such as metal soap, and then thermally decomposing them, but these organometallic compounds are relatively expensive and are a constraint for industrial use. There is. On the other hand, in addition to these organometallic compounds, metal oxide hydrosols such as alumina sol and silica sol can be used to form a film on the plastic surface. For example, JP-A-60-6918
The specification of Publication No. 1 proposes its use as an antifogging agent, and describes that titania hydrosol can also be used. However, this invention does not disclose any specific example of the use of titania hydrosol as an antifogging agent. According to the findings of the present inventors, titania hydrosol has a particle size? It has been found that by combining titania with titania, it is possible to improve the adhesion with the plastic surface, and that it can be suitably used to produce a plastic composite material that takes advantage of the functions of titania.

In addition to the above-mentioned thin film formation techniques, there are also known techniques such as sputtering, vacuum evaporation, and CVD, but all of these require a large amount of equipment and are unsuitable for creating large-area films. It is known.

<Problems to be Solved by the Invention> The present invention overcomes these drawbacks of the prior art, and uses a coating composition containing titania sol as a main component on reeds and plastic surfaces at low cost and with good workability. By forming a transparent titania film with good adhesion, the plastic has antistatic properties, selective light transmission properties, antifogging properties, light interference properties, heat resistance, chemical resistance, and functions as an immune carrier in the biomedical field. It comes from giving.

Measures to solve these problems> Originally, it was thought that organic polymeric materials such as plastics and inorganic materials such as metal oxide hydrosols had poor affinity, so it was necessary to form a homogeneous coating film with good adhesion on the plastic surface. was considered difficult to form. However, the present inventors have discovered that by miniaturizing titanium to 2 μm or less, the sol component in the titania hydrosol has a strong affinity for the plastic surface, has excellent adhesion, and is capable of forming a homogeneous titania-based thin film. The present invention was completed based on the discovery that

<Function> The reason why the coating composition mainly composed of titania hydrosol having the above-mentioned fine particle size has good adhesion to the plastic surface and forms a strong film is not clear, but the inventor of the present invention They think as follows. In other words, since the colloidal particles in titania hydrosol are minute, the surface area is large, and the many titanium hydroxyl group bonds present on the surface of the colloidal particles are chemically active. It is thought that the adhesion is enhanced by bonding or strong adsorption to polar groups caused by oxygen, nitrogen, etc. present in the plastic substrate, especially on the surface thereof. Furthermore, although a film is formed by dehydration condensation between particles, active titanium hydroxyl group bonds remain, so it is thought that the film exhibits antistatic ability, which is one of the functionalities aimed at by the present invention. Further, the formed titania film exhibits ultraviolet reflecting ability reflecting the hiding power, high refractive index, etc. of titania particles, and also has the property of exhibiting interference color depending on the film thickness. Also, since it is inorganic, it has improved heat resistance and chemical resistance. The average particle size of the colloidal particles of the titania hydrosol disclosed in the present invention is 0.1 μm or less, preferably 0.005 μm or less, in order to improve the adhesion of the titania film to the plastic substrate and further increase the light transmittance. More preferably 0.01 μm
It is prepared and used as follows.

There are no restrictions on the method for producing titania hydrosol described above, but for example, after hydrolyzing a salt such as titanium tetrachloride or titanyl sulfate to form orthotitanic acid particles, the method is decomposed with barium chloride, hydrochloric acid, nitric acid, etc. Methods such as glue and dialysis to remove contaminating impurity ions such as chloride ions,
Furthermore, in order to obtain a finely divided titania hydrosol, a titanium salt aqueous solution such as titanium tetrachloride or titanyl sulfate is preferably mixed with a KOH type anion exchange resin in the presence of a stabilizer such as a chelating agent such as acetic acid or acetylacetone. A method of hydrolysis is advantageously carried out. In some cases, titania may also include aluminum, zirconium,
Although it is possible to combine other metals such as tin, nickel, cobalt, and vanadium, this combination can also be easily performed by applying the above two methods.

The coating composition containing titania hydrosol as a main component disclosed in the present invention is a water solution, and if it contains titania colloidal particles as a titania hydrosol, it will adhere to the plastic surface by itself. It has excellent sexual properties, but in order to enhance its effect,
This hydrosol contains carboxylic acids such as acetic acid, alcohols such as methanol, esters such as ethyl acetate and methyl acrylate, and ethers such as ethyl ether.
Ketones such as acetone, lower hydrocarbons such as LPG and LNG, their halides, and reactive monomers such as acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate or their methacrylates, vinyl acetate, maleic acid, and ethylene oxide. Single or copolymeric water-soluble compositions or emulsions can be added.

In addition, a small amount of other surfactants and the like may be additionally added.

Applicable plastics include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polycarbonate, polymethyl methacrylate, nylon, Bakelite, epoxy resins, unsaturated and saturated polyester resins,
These are conventionally known resins such as AB8 resin, polyamide resin, and polyimide resin. Among these, resins containing oxygen or nitrogen atoms in their polymer chains have a particularly high affinity with the hydroxyl groups possessed by titanium atoms in the hydrosol and give favorable results. The shape of the plastic may be any shape such as plate, film, fiber, granule, or molded body.

When actually applying a coating composition containing titania hydrosol to plastic, spraying method,
Conventionally known methods such as dipping, bar coater, applicator, and brush coating can be applied. After forming a coating film on the plastic surface in this way, it is air-dried, heated to 200°C, dried under reduced pressure at room temperature, etc. to form a film that has high adhesion to the plastic surface and high film strength. It is formed.

Example I A) Production of titania hydrosol (5) Titanium ditetrachloride aqueous solution (Ti content 16.8%) 5611 was added to 260 ml of 7% by weight acetic acid aqueous solution to form a homogeneous solution.

Next, an anion exchange resin (Amberlite ■ IRA-6
8. Manufactured by Rohm Antonose Co., Ltd.) with wet resin for 300!
After adding 50% of the ion exchange resin and contacting the mixture at 25° C. for 5 minutes, the ion exchange resin was added to the mixture to produce a titania hydrosol. This sol contained 5.0% by weight of titania in Tie terms and 0.032% by weight of chlorine ions (Cl-). The particle size of the colloid was measured using a dynamic light scattering photometer (DLS-7).
00, manufactured by Union Giken), the average particle size is 3OA.
(0,003 μm).

B) Production of titania hydrosol (): Before adding the ion exchange resin in the production of titania hydrosol (5), put the above mixed solution of titanium tetrachloride aqueous solution and acetic acid aqueous solution into a flask equipped with a condenser and a stirring device. 50
Titania hydrosol (
Titania hydrosol (2) was produced in the same manner as in 5). The titania in this sol is TiO.

It contained 5.0% by weight (J-) and 0.28% by weight (J-).The particle size of the colloid was measured using the above-mentioned dynamic light scattering photometer, and the average particle size was 80A (o, oosμ77
L).

C) Heat treatment at 60° to 65°C in the production of titania hydrosol (Production of Q: titania hydrosol CB)
Titania hydrosol (q) was produced in the same manner as in the production of titania hydrosol (5), except that it was carried out for 30 minutes.This sol contained 5.4% by weight of titania in terms of TiO2 and 0% of C1-. The average particle size of the colloid was 120A (0.012 μm) when measured using the above-mentioned dynamic light scattering photometer.

Furthermore, these three types of titania sols did not gel or thicken and remained stable even after being left at room temperature for 3 months.

Three types of titania hydrosols (5) obtained above, however)
, 200 g of ethanol was added to 100 g of each of 0 to make a homogeneous solution, which was then applied to various plastic substrates using a bar coater and air-dried.

After that, heat treatment was performed at a temperature of 80 to 120° C. for 3 minutes to form a titania film on the plastic substrate.

At this time, it was found that when the thickness of the film was 0.2 μm or less, the titania film was transparent, but when it was 0.2 μm or more, it began to exhibit optical interference and the coating took on a reddish color. As a result of X-ray diffraction, all of these films showed no clear peaks and were amorphous. The surface resistivity, film formability, film strength, visible light transmittance, and antifogging properties of various film-treated plastic substrate surfaces were measured. The results are shown in Table-1. Note that each measurement method is as follows. Further, the film thickness was adjusted to approximately 0.1 μm.

・Surface specific resistance-YHP-4329A high re
sistance meter 16008A resi
The measurement was carried out using a stivity cell (manufactured by Hewlett Packard Co., Ltd.) at 25°C and a relative humidity of 30°C.

- Film forming property - The homogeneity of the coating film was visually observed and evaluated in four stages.

◎...Very good homogeneity ×...Does not form a film/Film strength-adhesion and peel test JIS-K 5
A cross-cut was prepared according to the method specified in 400.6.15, adhesive cellophane tape was applied to the surface, and the residual rate of the coating film was measured when it was rapidly peeled off.

- Visible light transmittance - Visible light transmittance (H) was measured using a total light transmittance measuring device (Model ND-1001DP) manufactured by Nippon Denden Industries.

・Anti-fogging property - The surface of the plastic coated with titania is facing the inside of the aquarium, and the outside temperature is maintained at 20°C and the temperature inside the aquarium at 30°C. After 30 minutes, the anti-fogging property of the plastic surface is checked with the naked eye. It was observed and evaluated.

The water droplets adhering to the surface did not form droplets and were spread in a thin film shape, and were marked as "○"; those that did not spread into a film and existed in droplets were marked as "△".

Comparative Example 1 In Example 1, the surface resistivity, visible light transmittance, and antifogging property of the polymethyl methacrylate substrate before forming the titania film were measured and found to be "1o16Ω or more", r9211, and "Δ", respectively.

Example 2 Figure 1 shows the measurement results of visible and ultraviolet absorption of the coating film formed on the polyethylene terephthalate substrate of Example 1.
Shown below. There is a large absorption peak at 310 nm, and this coating has ultraviolet absorption ability.

Comparative Example 2 Ethanol solution of titanium tetraisopropoxide (Ti
When 2.5% by weight (calculated as 0□) was applied to the same polymethyl methacrylate substrate as used in Example 1 and 1 and air-dried, it became gelled and became cloudy, resulting in poor film formability and film strength.

[Brief explanation of the drawing]

FIG. 1 shows the visible light and ultraviolet light absorption curves of the coating film observed in Flat 3 of Example 1.

Claims (4)

[Claims] (1) A plastic composite material formed by forming a transparent film on a plastic surface using a coating composition containing titania hydrosol as a main component. (2) The average diameter of colloid particles in the hydrosol is 0.0
Claims (1) characterized in that the diameter is 5 μm or less
) listed plastic composite materials. (3) The plastic composite according to claim (1) or (2), wherein the hydrosol is produced by hydrolyzing an aqueous titanium salt solution using an OH-type anion exchange resin. material. (4) Claim (1), (2) or (3), characterized in that the plastic is produced from a starting material composition containing nitrogen-containing and/or oxygen-containing monomers. plastic composite material.