JPH0232305B2 - CHITANIAKEIHIDOROZORUOFUKUMUTAIDENBOSHIZAI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a novel inorganic antistatic agent. Specifically, the present invention relates to an antistatic agent containing at least one titania-based hydrosol selected from the group of titania hydrosol, titania sol-alumina sol mixed hydrosol, and titania alumina composite hydrosol. Synthetic resin products such as fibers, sheets, and films made from synthetic resins are easily charged with static electricity, and the damage caused by this has become a variety of problems. The inorganic antistatic agent disclosed in the present invention exhibits an excellent antistatic effect that is not affected by humidity or changes over time when used as a surface treatment agent for the above synthetic resin products, and is of industrial significance. . <Conventional technology> In recent years, there has been a rapid increase in the number of products requiring antistatic properties such as clean benches, clean rooms, other electronic and electrical equipment, building materials such as flooring and wall materials, and textile products such as clothing and seat covers. ing. As a countermeasure, there is a method of kneading large amounts of conductive substances such as carbon fiber and metal powder into synthetic resin and molding it, but the purpose is to prevent the generation and accumulation of static electricity on the surface of synthetic resin products. Surface treatment with antistatic agents has attracted attention, and its use in small amounts is effective and has been widely applied. The surface treatment methods can be roughly divided into two: First, conductive paint mixed with carbon powder, carbon fiber, metal powder, metal fiber, fine powder of inorganic oxide such as tin oxide, indium oxide, etc. is applied to make the surface conductive. The second method is to apply ionically conductive organic substances such as quaternary ammonium salts and sulfonate salts, and the third method is to hydrolyze and condense metal alkoxides in the coating film (Japanese Patent Publication No. 36-4740). Publication specification),
Alumina hydrosol, silica sol (Special Publication 1969-
A method of applying an inorganic paint or the like that forms a glassy substance has been proposed, such as (Japanese Patent No. 6533 specification). However, these methods have the following drawbacks. That is, in the first method, the treated film becomes colored, such as gray or black, and a transparent coating film cannot be obtained. The second method is easily affected by humidity, and not only does it not have a sufficient antistatic effect in a low-humidity atmosphere, but it also loses its effectiveness after washing with water, the surface becomes sticky, and it is susceptible to ultraviolet rays. There are problems such as instability and coloring. Similar to the second method, the third method conventionally has problems such as not having a sufficient antistatic effect in a low-humidity atmosphere, and poor adhesion to the synthetic resin surface and easy peeling. Various attempts have been made to coexist with esters and the like as essential components, but they have drawbacks such as complicated processing after coating film formation, and are still not satisfactory. It is also known that films made from metal chlorides such as titanium tetrachloride and aluminum chloride have antistatic properties [Kobunshi, Vol. 10, pp. 371-373 (1961)]; However, it is said that it cannot be put into practical use due to drawbacks such as film strength. <Problems to be Solved by the Invention> The present invention is a method that falls within the scope of the third method described above, but it has problems with the complicated processing of conventional silica sol-based antistatic agents and the problems of alumina sol-based antistatic agents. This solves the drawbacks of known methods, such as poor adhesion to the resin surface and antistatic effect, as well as poor transparency and film strength in systems made from titanium tetrachloride and aluminum chloride, and achieves antistatic effect even at low humidity. , has excellent adhesion to synthetic resin surfaces, and does not deteriorate over time.
The object of the present invention is to provide an antistatic agent that stably protects the surface of a synthetic resin and is easy to process. <Means for Solving the Problems> The present invention was discovered while investigating the antistatic effects of many inorganic materials in order to solve the various problems of the existing antistatic agents mentioned above. Its feature is that it is an antistatic agent containing at least one titania hydrosol selected from the group of titania sol, titania sol-alumina sol mixed hydrosol, and titania alumina composite hydrosol. <Function> The antistatic agent containing the titania-based hydrosol described above has better adhesion to the synthetic resin surface than other inorganic agents, forms a firm film, and exhibits sufficient antistatic effect even in a low-humidity atmosphere. Although the reason for this is not clear, the present inventors think as follows.
In other words, since the colloidal particles in the titania-based hydrosol are minute, the surface area is large, and the titanium hydroxyl groups present in large numbers on the surface of the colloidal particles are chemically active, resulting in strong bonding through a small amount of adsorbed water on the surface of the synthetic resin. It is thought that the adhesion is high due to strong adsorption to polar groups such as oxygen and nitrogen present in the synthetic resin and on the surface.
In addition, regarding the antistatic ability, the colloidal particles applied to the surface of the synthetic resin form a film through dehydration and condensation between the particles while water and other solutions in the system scatter, but ultimately the cross section of the film is porous. It is thought that there is a space corresponding to the colloid particle size, around which a large amount of active titanium hydroxyl groups are distributed, and these groups provide a strong antistatic ability. The titania sol-alumina sol mixed hydrosol is simply a mixture of titania hydrosol and alumina hydrosol. When producing both sols,
The titania colloid particles in titania hydrosol tend to be nearly spherical, while the alumina colloid particles in alumina hydrosol tend to be feather-shaped, but if we look only at their physical shape, Aggregates with irregular shapes such as feathers are more effective in entangling the particles during film formation, resulting in a stronger film, but alumina alone has a weak affinity with the synthetic resin surface, resulting in easy peeling. There is. The titania sol-alumina sol mixed hydrosol maintains the strong adhesion of titania colloid particles to the synthetic resin surface and utilizes the shape specificity of alumina colloid particles to improve film strength. Furthermore, a synergistic antistatic effect is expected by controlling the valences by bonding two metals with different valences via oxygen atoms. Titania alumina composite hydrosol is produced by using titanium compounds such as titanium tetrachloride, titanyl sulfate, titanyl nitrate, titanium oxalate, and titanium tetraisopropoxide, and aluminum such as aluminum chloride, aluminum nitrate, aluminum acetate, and aluminum isopropoxide. It is a composite hydrosol that simultaneously hydrolyzes both components from a mixed solution of the compound and has titanoxane bonds and aluminoxane bonds in the molecular chain. In this case, the shape of the composite colloidal particles changes depending on the composition ratio of titanium and aluminum, but it is possible to increase the condensation rate of the two metals with different valences through the oxygen atoms mentioned above. It is thought that this results in a synergistic antistatic effect. In these titania sol-alumina sol mixed hydrosols and titania alumina composite hydrosols according to the present invention, the content ratio of titanium and aluminum therein is such that the titanium/(aluminum + titanium) atomic ratio is 0.1 or more, especially for the reasons mentioned above.
The range is preferably 0.2 or more. There are no restrictions on the method for producing the above hydrosol, but in the case of titania hydrosol, for example, salts such as titanium tetrachloride and titanyl sulfate are hydrolyzed to form orthotitanic acid particles, and then barium chloride, hydrochloric acid, etc. Either by peptizing and removing contaminating impurity ions such as chloride ions by dialysis, or by partially hydrolyzing titanium alkoxide such as titanium tetraisopropoxide in an alcohol solution, adding a stabilizer and adding water as a solution. Preferably, a method in which an aqueous solution of a titanium salt such as titanium tetrachloride or titanyl sulfate is hydrolyzed using an OH-type anion exchange resin in the presence of a stabilizer such as acetic acid is industrially advantageous. be done. The titania alumina composite sol can also be produced in the same manner as the titania hydrosol, except that the aluminum raw material is uniformly dissolved in the titanium raw material. Conventionally known methods are applied to aluminum hydrosol, for example, the method described in JP-A-59-223223,
The method described in JP-A-59-78925 can be used, but commercially available methods may also be used as they are. As mentioned above, the smaller the colloid particle size in the titania hydrosol, titania sol-alumina sol mixture, and titania alumina composite sol produced by the above method, the better the antistatic effect, adhesion, and film strength. Since the synthetic resin becomes transparent after antistatic treatment, it is preferable to use a synthetic resin having an average diameter of 0.1 μm or less. The antistatic agent disclosed in the present invention uses water as a solvent, and if it contains titania-based colloidal particles as a titania-based hydrosol, it alone has a high antistatic effect when used as a treatment agent, and it can be used as a treatment agent for synthetic resins. It has excellent adhesion to the surface, but in order to further enhance the effect, in some cases carboxylic acids such as acetic acid, alcohols such as methanol and ethanol, esters such as ethyl acetate and methyl acrylate, ethyl ether, etc. ethers, ketones such as acetone, lower hydrocarbons such as LPG and LNG, their halides, and (meth)acrylic acid, 2-hydroxyethyl (meth)acrylate, vinyl acetate, maleic acid, ethylene oxide, etc. Water-soluble or emulsified mono- or copolymers of reactive monomers can be added. Small amounts of commonly used organic antistatic agents such as quaternary ammonium salts, cationic, anionic or amphoteric surfactants may also be added. Applicable synthetic resins include conventionally known resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polycarbonate, polymethyl methacrylate, nylon, Bakelite, epoxy, unsaturated and saturated polyesters, ABS, polyamide, and polyimide. Among these, resins containing oxygen or nitrogen atoms in their polymer chains are particularly preferred because they have a particularly high affinity with the hydroxyl groups strongly held by the titanium element in the hydrosol. Its shape is plate-like, film-like,
It may be in any shape such as fibrous or molded body. When actually antistatically treating a synthetic resin using the antistatic agent of the present invention, conventionally known methods such as spraying, dipping, bar coater, applicator, and brushing can be applied. After forming a coating film of antistatic agent on the synthetic resin surface in this way, it is air-dried, heated to 200℃, dried under reduced pressure at room temperature, etc. to improve the adhesion to the synthetic resin surface and increase the film strength. An antistatic coating is formed. Next, the present invention will be explained in more detail with reference to Examples. Example 1 59g of titanyl sulfate (TiOSO _{4.2H 2} O) at 55℃
After dissolving the solution in 600 ml of hot water, the solution was cooled to 10° C., and 50 ml of 28% ammonia water was added to precipitate titanium hydroxide. The precipitate was washed with 800 ml of pure water to obtain a titanium hydroxide cake. The cake obtained above was placed in an ice-cooled 500 ml glass beaker, and while stirring, 53 g of concentrated nitric acid was gradually added dropwise to peptize the titanium hydroxide and form a transparent titania sol solution. This transparent liquid was placed in a cellophane dialysis membrane and dialyzed for 3 hours against a 5% by weight acetic acid aqueous solution to replace the counter ion nitrate ion with acetate ion, yielding a stable titania hydrosol with a low impurity content. The composition of this sol is 8.5% by weight of titania (calculated as _TiO2 ), 4.8% by weight of acetic acid, 1.0% by weight of _NO3 , and 1.0% by weight _of ^SO2-4 .
The particle size of the colloid was 20 to 40 Å when observed with a transmission electron microscope. Furthermore, this sol remained stable without gelling or thickening even after being left at room temperature for 3 months. The titania hydrosol obtained above was applied to a polyethylene terephthalate resin (hereinafter abbreviated as PET) film with a thickness of 50 μm using a No. 8 bar coater, and air-dried overnight or with hot air at 120°C.
A titania film was formed on PET film.
As a result of X-ray diffraction, these films were all found to be amorphous. The surface resistivity, film formability, and film strength of the coated PET surface were measured. The results are shown in Table-1. In addition, each measurement method is as follows.・Surface specific resistance - YHP-4329A high resistance
Measurement was performed at 25° C. and relative humidity of 30% using meter 16008A resistivity cell (manufactured by Yokogawa Heuretsu Patscard Co., Ltd.).・Film forming property - The homogeneity of the coating film was visually observed and evaluated in four stages. ◎…Very good homogeneity〇…Almost homogeneous △…Relatively many areas that are not homogeneous×…Does not form a film ・Film strength - Adhesiveness was tested using a square peel test JIS-
A cross-section was prepared according to the method specified in K5400 6.15, an adhesive tape was attached to the surface of the cross-section, and after the adhesive tape was rapidly peeled off, the number of coatings remaining on the cross-section was measured. Example 2 The titania hydrosol and alumina hydrosol (Nissan Chemical Co., Ltd. Alumina Sol-200 particle size 100 x 1000 Å) obtained in Example 1 were mixed with titanium/aluminum =
They were mixed at a 1/1 (atomic ratio) to obtain a titania hydrosol-alumina hydrosol mixture. Example 1 was carried out in the same manner as in Example 1, except that the above mixed sol was used instead of the titania sol, and a polymethyl methacrylate resin (PMMA) plate was used instead of the PET film, and the results shown in Table 1 were obtained. Example 3 28 g of titanium tetrachloride (titanium content 16.8% by weight) and 110 g of _aluminum nitrate (Al(NO ₃ ) 3.9H ₂ O)
was added to 600 ml of a 7% by weight acetic acid aqueous solution to form a homogeneous solution. Next, add ion exchange groups to the solution in advance by adding OH
470 g of an anion exchange resin (Amberlite IRA 68, manufactured by Rohm and Haas) which had been converted into a mold was added and allowed to contact at 25° C. for 1 minute, and then the ion exchange resin was separated to produce a titania alumina composite hydrosol. The composition of this composite sol is Ti/Al = 1/3 (atomic ratio), and the titania-alumina composite colloid is TiO ₂
-Calculated as Al ₂ O ₃ , it is 3.2% by weight, and Cl ^- is 0.7% by weight.
NO ^- ₃ was 1.0% by weight and acetic acid was 5.3% by weight. The particle size of the composite colloid is 50~150Å x 500~
It had an irregular shape of 1000 Å. Example 1 was carried out in the same manner as in Example 1, except that the composite sol obtained above was used instead of the titania sol and a polycarbonate (PC) plate was used instead of the PET film, and the results shown in Table 1 below were obtained. Example 4 A composite sol of Ti/Al=3/1 (atomic ratio) was obtained in the same manner as in Example 3, and a coating film was formed using the composite sol. I got the results. Comparative Example 1 The same procedure as in Example 1 was carried out except that only the alumina hydrosol used in Example 2 was used as an antistatic agent, and the measurement results shown in Table 1 below were obtained. Comparative Example 2 An ethanol solution of titanium tetraisopropoxide (titanium content 8% by weight in terms of TiO ₂ ) was prepared in Example 1.
When it was similarly applied onto a PET film and air-dried, it turned into a gel and became cloudy, resulting in very poor film formability and film strength. 【table】

Claims (1)

[Scope of Claims] 1. An antistatic agent characterized by containing at least one titania hydrosol selected from the group of titania hydrosol, titania sol-alumina sol mixed hydrosol, and titania alumina composite hydrosol. 2 The average diameter of colloidal particles in the hydrosol is
The antistatic agent according to claim 1, wherein the antistatic agent has a particle size of 0.1 μm or less.