JPS5863729A - Manufacture of surface-modified molded resin article - Google Patents

Abstract

PURPOSE:To obtain the titled molded article having durable antifogging property, by applying an organic solvent solution of a water-insoluble anionic polymer electrolyte to the surface of a molded article made of e.g. PE to form a coating film thereon, and adsorbing inorganic colloidal sol having positive charge to the coating film. CONSTITUTION:The surface of a molded resin article (e.g. film, sheet, etc. of PE or PP) is coated with (A) an acetone solution of a water-insoluble and organic solvent-soluble anionic polymer electrolyte obtained e.g. by the copolymerization of a monomer having anionic ionizable group (e.g. sodium styrenesulfonate) and a vinyl monomer free of ionizable group (e.g. styrene) to form a coating film, which is further coated with (B) an aqueous dispersion of inorganic colloidal sol having positive charge (e.g. alumina sol). The inorganic colloidal sol (B) is adsorbed to the coating film of the electrolyte (A) to obtain the objective molded article. USE:Goggles, safety mask, agricultural film, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a surface-modified resin molded article. More specifically, the present invention relates to a method for producing a molded article whose purpose is to impart antifogging properties to the surface of a thermoplastic resin molded article and maintain this antifogging property for a long period of time.

Conventionally, various thermoplastic FA fats have been industrially produced,
It has been used in a wide range of fields. Many of the molded products made from these thermoplastic resins have hydrophobic surfaces, so depending on the conditions such as temperature and humidity in which the molded product is used,
The surface becomes cloudy, causing various inconveniences. For example, goggles, safety masks, etc. that use synthetic resin lenses may become foggy, making it difficult to see, and food packaging films may become cloudy, making it difficult to see the contents. Agricultural films that are used for agricultural purposes are cloudy, which impairs the penetration of sunlight, slowing down plant growth, and causing water droplets to fall on cultivated plants, damaging young buds and causing diseases. It happens.

In order to eliminate such inconveniences, it is known that antifogging properties may be imparted to the surface of the thermoplastic resin molded product 41. In order to impart antifogging properties to the surface of a thermoplastic resin molded product, a hydrophilic substance such as a surfactant may be kneaded into the thermoplastic resin to form a molded product, or the surface of the molded product may be coated with A method of applying a hydrophilic substance or a water-soluble polymer has been adopted.

However, in the former method, the hydrophilic substance kneaded into the thermoplastic resin exudes onto the surface of the molded product and coordinates.
It imparts anti-fog properties to molded products, but it is easily washed away by water, and the anti-fog properties deteriorate over time.
・There are some drawbacks. On the other hand, in the latter method, the applied hydrophilic substance or water-soluble polymer easily dissolves in water, so it exhibits excellent antifogging properties immediately after application, but it is easily washed away by water and deteriorates over time. Along with this, the antifogging property decreases. In order to solve this problem, attempts have been made to reduce the solubility of hydrophilic substances or water-soluble polymers in water, but this also reduces the antifogging properties themselves. This cannot be said to be a satisfactory improvement method. In addition, a method has been proposed in which the water-soluble polymer applied to the surface of the molded product is crosslinked to reduce its solubility in water.However, this method can only be adopted if a specific structure is In addition to being limited to water-soluble polymers, it is necessary to cause a crosslinking reaction on the coated surface after coating it on the surface of the molded article, making the process complicated and therefore not a desirable method.

Under such circumstances, the present inventors have provided an industrially advantageous method for imparting antifogging properties to the surface of a thermoplastic resin molded product and maintaining the antifogging properties for a long period of time. It was completed as a result of intensive study.

The gist of the present invention, however, is that when producing a surface-modified resin molded product, a film of anionic polymeric acid delyte, which is insoluble in water and soluble in organic solvents, is applied to the surface of the molded product. The present invention relates to a method for producing a surface-modified resin molded article, which comprises forming a film and adsorbing a positively charged inorganic colloid sol onto the film.

The following is a detailed explanation of the present invention. In the present invention, resins include polyethylene, polypropylene, polystyrene,
Polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polycarbonate, polyamides, polyacetal,
It refers to thermoplastic resins such as polyesters, but is not limited to these examples.

In the present invention, the molded product may be any molded product made of the above thermoplastic resin, and there are no restrictions on the shape, dimensions, etc. of the molded product. Among the molded products, films, sheets, plastic V-), etc. are preferable because the present invention can be easily applied thereto.

In the present invention, first, a film of an anionic polymer electrolyte that is insoluble in water and soluble in organic solvents is formed on at least one surface of a thermoplastic resin molded article. This anionic polymer electrolyte film has the function of adsorbing a force-strengthening polymer electrolyte, which will be described later.

It is necessary to select an anionic polymer electrolyte that is insoluble in water but soluble in organic solvents. If it is soluble in water, it will be dissolved in water and washed away, making it impossible to maintain the antifogging properties of the molded product, which is undesirable.If it is not soluble in organic solvents, a film will form on the surface of the molded product. This is because it is difficult to do.

In general, what is called a polymer electrolyte is a polymer substance that has many ionizable groups, and it dissolves in water.
Dissociates into charged polymer ions and low molecular ions.

Polyelectrolytes with many ionizable groups are soluble in water but insoluble in common organic solvents. When such a polymer electrolyte is applied to the surface of a molded article, it dissolves in water adhering to the surface of the molded article and is washed away.

Even with polymer electrolytes, if the number of ionizable groups is reduced,
This also causes a large change in its solubility in α refrigerants, showing the property that it is insoluble in water but soluble in certain organic solvents, such as polar solvents and mixtures of polar solvents and water. Now, we will show the characteristics of polymer electrolytes.

Anionic polymer electrolytes that are insoluble in water and soluble in organic solvents can be produced by any of the following methods.

+11 7 A method of copolymerizing a monomer with an ionizable group and a vinyl monomer without an ionizable group.

For example, styrene sulfone hydrated sodium and vinyl-based 1*
A method of copolymerizing with polymers.

Examples of copolymerizable vinyl monomers include acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, 1-propyl acrylate, 1-butyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate; Methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, 1-propyl methacrylate, 1-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate: 2-hydroxyethyl Hydroxyl group-containing acrylic acid alkyl esters such as acrylate, 2-hydroxypropyl acrylate, diethylene glycol monoacrylate, triethylene glycol monoacrylate, and tetraethylene glycol monoacrylate; acrylic acid, methacrylic acid,
Examples include itaconic acid, fumaric acid, acrylonitrile, methacrylonitrile, styrene, vinyl chloride, etc., but are not limited to these examples.

To produce the copolymer, conventionally known methods such as suspension method, emulsion polymerization method, solution polymerization method, and bulk polymerization method can be employed.

(2+ A method in which a vinyl monomer that does not have an ionizing group is subjected to a craft reaction with an anionic polymer electrolyte.

Examples of anionic polymer electrolytes include sodium alginate,
carboxymethyl cellulose salt, cellulose sulfate salt, polyacrylic acid and its sodium salt,
Examples include polymethacrylic acid and its sodium salt, sodium salt of maleic acid copolymer, sodium salt of polystyrene sulfonic acid, and sodium salt of polyacrylamide partial hydrolyzate. These are dissolved and dispersed in an organic solvent or a mixture of an organic solvent and water to graft the vinyl monomers listed in (1).

(3) A method of introducing a carboxyl group, a sulfonic acid group, or a sulfate ester group into a breast molecule that does not have an ionizable group.

(4) A method of neutralizing carboxyl groups and sulfonic acid groups in the molecular chains of polymer needles.

In the method of the present invention, an anionic polymer electrolyte film produced by the above method that is insoluble in water and soluble in organic solvents is formed on the surface of a molded article. The film formed on the surface of the molded article may cover the entire surface or may be formed on a part of the surface.

To form a film on the surface of a molded article, the anionic polymer electrolyte that is insoluble in water and soluble in an organic solvent is dissolved in an organic solvent and applied to the molded article. Organic solvents that can be used at this time include tetrahydrofuran, dioxane, methylene chloride, cyclohexanone, isopropyl alcohol,
Examples include dimethylformamide and acetone. These can be used alone or mixed with water.

As a method for forming a film on the surface of a molded product, a method can be employed in which coating is applied using a technique normally employed for forming this type of film, and an organic solvent is scattered. The coating method can be appropriately selected from roll coating, spray coating, dip coating, knife coating, etc. depending on the shape and size of the molded product. To scatter the organic solvent, a hot air drying method, a drying method using infrared irradiation, or the like can be employed.

The thickness of the film thus formed on the surface of the molded article is preferably in the range of several microns to several tens of microns.

In the present invention, a positively charged inorganic colloidal sol is adsorbed onto the film formed on the surface of the molded article by the above method. This is because the anionic polymer electrolyte previously formed on the molded product is insoluble in water, and this alone cannot impart optical antifogging properties to the surface of the molded product.

Generally, when particles having a diameter of 1 mμ to 100 mμ are dispersed in a dispersion medium to create a stable dispersion system, this dispersion system is called a colloid or colloid sol. The reason why such ultrafine particles can be stably dispersed in a dispersion system is thought to be because the surfaces of the ultrafine particles (referred to as colloidal particles) have an electric charge. Colloidal particles have either a positive or negative charge (are charged), and which charge they have depends on the composition of the colloidal particles and the method of preparing the particles. Which charge a colloidal particle has can be easily determined by electrophoresis.

Among inorganic colloids, colloids of inorganic oxides and inorganic hydroxides are preferable as colloid particles that can be used in the present invention.

This is because colloids of these materials are highly hydrophilic and help improve the wettability of the surface of the molded product.

The above-mentioned inorganic colloidal sol may be prepared by any known method. Among positively charged inorganic colloidal sol,
Alumina sol is the most common.

In order to adsorb the above-mentioned positively charged inorganic colloidal sol onto the film formed on the surface of the molded product, this colloidal sol is dispersed in a medium such as water or alcohol, and then coated using a roll coating method, a spray coating method, or a tube coating method. law,
It may be applied by a knife coating method or the like, and the medium may be scattered by drying.

The ionizable groups of the positively charged inorganic colloid particles and the anionic polymer already formed on the surface of the molded article are not necessary, and the former may be overwhelmingly present.

The present invention has the following effects, and its industrial utility value is extremely significant.

(1) The method of the present invention involves forming a film of an anionic polymer electrolyte that is insoluble in water and soluble in organic solvents on the surface of a thermoplastic resin molded product, and on top of this film, a positively charged inorganic colloid sol is applied. Since the method of adsorbing is adopted, the manufacturing process is not complicated and is industrially advantageous.

(21) The surface of the molded product obtained by the method of the present invention is modified by a combination of an anionic polymer electrolyte and a positively charged inorganic colloid, so the wettability of the surface of the molded product is significantly improved. The water droplets adhering to the surface of the molded product are formed into a thin film, resulting in excellent antifogging properties.

(3) On the surface of the molded article obtained by the method of the present invention, the film formed as a base is made of an anionic polymer electrolyte that is insoluble in water, so this film will not be washed away by water. In addition, since the positively charged inorganic colloid vine adsorbed on this film is ionically adsorbed with the anionic polymer electrolyte, this material is also easily washed away by water.・. As a result, the antifogging property of the molded product surface is maintained for a long period of time.

Hereinafter, the present invention will be explained in detail based on examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof. The anionic polymer electrolyte used in the following examples was synthesized according to the synthesis example shown below.

Synthesis Example 1゜(Synthesis of acrylic anionic polymer electrolyte) Reflux vessel,
Capacity 5 [IQme three-loaf flask with a stirrer, 2
5019 of isopropyl alcohol was added. To this, methyl methacrylate 60g butyl methacrylate 601! 10 g of methacrylic acid was added, and the mixture was reacted at 80 C for 8 hours with stirring under a nitrogen blanket.

After the reaction was completed, sodium hydroxide was added in an amount to neutralize half of the methacrylic acid component, and the resulting polymer was made into an electrolyte.

The chemical compound is insoluble in water, and is compatible with acetone, alcohols,
It was soluble in ethyl acetate.

The product was prepared as a 2% by weight solution in alcohol.

Synthesis Example 2 (Synthesis of maleic anhydride-based anionic polymer electrolyte) A commercially available styrene-maleic anhydride copolymer (maleic anhydride content 25% by weight) was dissolved in acetone,
Sodium hydroxide was added to electrolyte the copolymer so that 20% of the maleic anhydride groups were neutralized.

This product was insoluble in water and soluble in acetone, dimethylformamide 3, tetrahydrofuran, and dioxane.

The product was dissolved in a mixed solvent with a weight ratio of tetrahydrofuran and water of 8:10 to form a 2% by weight solution.

Synthesis Example 3 (Synthesis of styrenic anionic polymer electrolyte) A monomer mixture of 95% by weight of styrene and 5% by weight of sodium styrene sulfonate was polymerized by emulsion polymerization to obtain a copolymer.

This copolymer was insoluble in water and soluble in acetone, dimethylformamide, tetrahydrofuran, dioxane, and the like.

The product was dissolved in a mixed solvent with a weight ratio of tetrahydrofuran and water of 8:1 to form a 2% by weight solution.

Examples 1 to 3 On one side of a soft polyvinyl chloride film (manufactured by Mitsubishi Monsanto Chemical Co., Ltd., right vinyl) with a thickness of 0.1 mti,
The anionic polymer electrolyte shown in the synthesis example (all solutions were 2% by weight) was applied by roll coating and dried at a temperature of 120 t:'.

As above, a film of anionic polymer electrolyte is formed on one side of the film, and on this film, a water bath solution of alumina 100) is applied at one time by spray coating method.
It was dried at a temperature of c.

The film thus prepared was spread over a water tank kept at a water temperature of 5 oc, with the coated side facing down, forming an inclination angle of 5 degrees to the water surface. The condensation situation was observed with the naked eye. Table 1 shows the observation results of antifogging properties over time.

In Table 1, the indication of anti-fog durability has the following meanings.

A--Things showing equivalent anti-fogging properties based on the one showing the most excellent anti-fogging properties immediately after stretching.

B--Those exhibiting anti-fogging properties of about 80%, based on those exhibiting the most excellent anti-fogging properties immediately after stretching.

C--Those exhibiting anti-fogging properties of about 60%, based on those exhibiting the most excellent anti-fogging properties immediately after stretching.

D-11 Those exhibiting anti-fogging properties of about 40% based on those exhibiting the most excellent anti-fogging properties immediately after expansion.

E--Things exhibiting anti-fogging properties of about 20% or less based on those showing the most excellent anti-fogging properties immediately after stretching.

Comparative Examples 1 to 3 The same flexible polyvinyl chloride film used in the above examples was coated with an anionic polymer electrolyte film that was insoluble in water and soluble in organic solvents (Comparative Example 1); A film was formed using a 2% by weight aqueous solution of sodium alginate, which is an anionic polymer electrolyte soluble in (Comparative Example 3), and a film was formed using the material shown in Synthesis Example 1 (
Comparative Example 6) was prepared.

Of these six types of films, two types of films, Comparative Example 1 and Comparative Example 2, were further adsorbed with aluminium in the same manner as described in the above example.

These six types of films were also evaluated for antifogging durability using the same method as shown in the above examples.

The results are shown in Table 1.

Table 1 ■ From Table 1, the following is clear.

(1) The molded product obtained by the method of the present invention has significantly superior surface wettability and exhibits excellent antifogging properties.

(2) The antifogging properties of the molded products obtained by the method of the present invention do not deteriorate significantly over time;
Therefore, the anti-fog durability is excellent.

(3) On the other hand, the one shown in the comparative example without a film does not have alumina sol adsorption, so it does not exhibit antifogging properties (Comparative Example 1) and has poor surface wettability (Comparative Example). 6),
Furthermore, anti-fogging durability is poor (Comparative Example 2).

Examples 4 to 6 On one side of a biaxially oriented polystyrene sheet (manufactured by Mitsubishi Monsanto Chemical Co., Ltd., Sand Clear) with a thickness of 0.18+m,
The anionic polymer electrolyte shown in the synthesis example (all 2% solutions) was applied by roll coating and dried at a temperature of 80C.

On the anionic polymer electrolyte film thus formed on one side of the sheet, a 1% by weight aqueous solution of alumina sol was applied by spraying and dried at a temperature of 70C.

The sheet prepared as above was spread on a water tank maintained at 50C in the same manner as described in Examples 1 to 3, with the coated surface facing the water side and tilted at 5 degrees with respect to the water surface. The state of condensation of water droplets on the sheet coating surface was observed with the naked eye. Table 2 shows the observation results of antifogging properties over time.

The indication of anti-fog durability in Table 2 has the same meaning as in Table 1.

Biaxially oriented polystyrene 7-sheets of the same type as used in the above example were prepared without forming a film of an anionic polymer electrolyte that is insoluble in water and soluble in organic solvents (Comparative Example 4), and in cases where a film was formed (Comparative Example 4).
Comparative Example 5) and one in which a film of a 2% by weight water bath solution of sodium alginate, which is a water-soluble anionic polymer electrolyte, was formed (Comparative Example 6) were prepared.

A cationic polymer electrolyte was adsorbed on two types of sheets except for the sheet of Comparative Example 5 in the same manner as described in the above example.

These three types of sheets were also evaluated for antifogging durability using the same method as shown in the above examples. The results are shown in Table 2.

No. 2B Although the type of resin of the molded product was different from that shown in Table 1, the effects of the present invention that were clear from No. 1 were also confirmed by this Table 2.

Patent applicant Mitsubishi Monsanto Chemicals Co., Ltd. agent Patent attorney - (1 other person)

Claims (1)

[Claims] (In producing a resin molded product with modified 11F2 surfaces, a film of an anionic polymer electrolyte that is insoluble in water and soluble in organic solvents is formed on the surface of the molded product. on the membrane,
A method for producing a surface-modified resin molded article, which comprises adsorbing a positively charged inorganic colloid sol. (2) A method for producing a surface-modified resin molded article according to claim 1, wherein the positively charged inorganic colloidal sol is an alumina sol.