JPS58138735A - Surface modification of molded plastic article - Google Patents

Abstract

PURPOSE:To obtain a coating film prepared from a curable substance, and having high adhesivity to the substrate and excellent surface state, by forming a modified layer to the surface of a molded plastic article by plasma treatment, and washing the modified layer with a solvent. CONSTITUTION:A molded plastic article (e.g. molded article of polymethacrylate resin) is subjected to the plasma treatment (e.g. in the mixture of oxygen and inert gas under the following conditions: flow rate, 10-300ml/min; pressure, 0.5-2Torr; power of electric discharge, 50-500W; and treatment time, 0.2- 10min). After washing the produced modified layer with a solvent (e.g. methanol) using an ultrasonic cleaner, etc., the surface is coated with a curable substance (e.g. curable acrylic composition), and the coating layer is cured to obtain the objective coating film.

Description

[Detailed description of the invention] related.

In recent years, the development of plastic has progressed, and it has attracted attention as a lightweight wood alternative to materials such as metal and inorganic glass. It became so. For example, glass molded products such as polymethacrylic esters, polyacrylic esters, polycarnates, and polyallylcarnates, which have excellent JFC transparency, can be used in optical applications such as AM lenses and heavy machinery glass instead of inorganic glasses. It has come to be used as a product. However, plastic molded products generally have the disadvantage of poor properties such as scratch resistance and chemical resistance. Therefore, in order to improve the scratch resistance, it is common to use a hardening substance such as melamine resin, acrylic resin, or silicone resin to form a coat on the surface of a plastic molded product. I'm doing it. However, the problem with surface modification of plastic molded products by the above method is that the n. This is the adhesion between the coating film and the glass molded product. Conventionally, the dense vIcI
As a method of increasing J, a method of forming a coat through an undercoat layer, or adding a third component to the curable material to form a dense layer! Improvement methods have been proposed.

However, the former method may have an adverse effect on the smoothness and weather resistance of the coated film in which the undercoat is formed from a curable substance. However, the latter method may cause discoloration of the coat group and deterioration of performance due to the third component added. These problems are fatal to the above-mentioned transparent glass molded products, and seriously reduce their commercial value.

Therefore, it has been desired to develop a method for improving the adhesion between a coating film formed of a curable substance and a plastic molded product without causing the above-mentioned problems.

The non-inventors have conducted extensive research to solve the above problems.

As a result, by applying VF plasma treatment to a plastic molded product to form a modified layer on its surface, and washing the modified layer with a solvent, the adhesion to the coating film formed by the curable substance is improved and improved. The present invention was proposed based on the fact that the surface condition of the coated film is extremely good.

In the present invention, a plastic molded product is treated with plasma to form a modified layer on its surface! This is a method for surface modification of plastic molded products, in which the modified layer is formed, and then the modified layer is washed with a solvent, and then a curable substance is applied and hardened to form a mold and V% mold.

In the present invention, plasma treatment of the modified layer and the Fif plastic product results in molecular chain scission, modification, etc. in the layer portion! say.

In the present invention, there is no particular restriction on plastic if-type products. Generally, plastic molded products with good scratch resistance are targeted. For example, polyunsaturated esters such as polymethyl methacrylate, polymethacrylate, polyethylene terephthalate, polyacrylate, polymethyl acrylate; polystyrene; polyvinyl chloride: epoxy resin; polyamides: polycarnate; polydiethylene glycol bisallyl carbonate etc.; Polymers such as cellulose acetate plastics, or molded products made of heptamers forming a single union of these or co-electric combinations of the heptamers and other monomers. I will. Among others, the transparency of polymethacrylic esters, polyacrylic esters, polycarnates, and polyallyl carmenate-based polymers has a tRr
For plastic molded products with +
0 and 1 are particularly effective.
1. The most important feature of the present invention is that a gelastec molded product is plasma-treated to form a modified layer on its surface, and then the modified layer is washed with a V solvent.

In the past, there have been examples in which plasma treatment has been used for the purpose of improving the adhesion of plastic molded products, such as plastic films. However, the adhesion of the coating film formed by the curable substance described below is similar to that of a plastic molded product! Mere plasma treatment is not fully satisfactory. In addition to this, gelastec molded products simply subjected to plasma treatment have the problem that the coat formed by the curable substance has uneven thickness and the surface condition is extremely poor.

In the present invention, an NFC formed by plasma treatment is used.
p1 plastic lR by washing the modified layer with a solvent.
The adhesion between the molded product and the coating film can be significantly improved, and the surface quality is extremely good! ! ! Coat film with 1! It becomes possible to form.

In the present invention, plasma treatment can be performed by a known method. For example, as the atmospheric gas, oxygen, a mixed gas of # and an inert gas such as alpane, etc. are suitably used. In particular, a mixed gas of oxygen and an inert gas is preferable because it has a large effect on plasma treatment. Also, the pressure is θ,
The gas flow rate is about S-Torr, but the gas flow rate is lO~J00
About @l/min is reasonable. Furthermore, the discharge power line generally has to be selected within the range of go-so. Furthermore, although the processing time varies somewhat depending on the magnitude of the discharge power and cannot be determined in general, it is generally O,2~
70 minutes is preferred.

Further, in the present invention, the modified layer formed on the surface of the GELASTEC molded product is cleaned to such an extent that a portion of the modified layer remains. In other words, cleaning to remove all the modified layer is
This is not preferable because it is not possible to obtain a sufficiently dense layer Y of the coating film without almost completely losing the effect of the plasma treatment. The solvent used for cleaning can be used without any particular restriction as long as it has the ability to remove at least a portion of the **Y present in the kinetically modified layer. In general, it is preferable to use a solvent that does not substantially dissolve the base material of the plastic molded product, since there is no risk that the entire modified layer will be dissolved.

Examples of typical solvents include methanol, ethanol,
Examples include alcohol solvents such as isopronosol, ketone solvents such as acetone, organic solvents made singly or in combination with aromatic solvents such as benzene and toluene, and aqueous solutions of neutral detergents such as dodecylbenzenesulfonic acid. Ru. Also,
As specific examples of combinations with plastic molded products, for example, methanol is suitable for hard metal fkyl I and IJ v-), and acetone is suitable for pyridethylene glycol pisallyl carcanate. The cleaning method using a solvent is not particularly limited. For example, commonly used methods include immersion in a solvent, a combination of this method and cleaning using an ultrasonic cleaner, a method of spraying a solvent, and a method of wiping with a cloth, paper, etc. containing a solvent.

A combined method of cleaning using an ultrasonic cleaner is preferred because the cleaning can be completed in a single hour.

In the present invention, the surface of the plastic molded product is modified by cleaning it with a modifying layer VM agent, then contacting it with a saponifiable substance and curing it. Of course, before applying the curable substance, any remaining bath agent on the surface should be removed by drying or other means. As the curable substance used in the present invention, a so-called crosslinkable substance that reacts with heat, a catalyst, a curing agent, etc. to form a three-dimensional network structure can be used without particular limitation. For example, melamine thread curable compositions made of melamines and other reactive substances such as formaldehyde, acrylic curable compositions made of acrylic esters, acrylamides, etc., and other reactions such as epoxies and bisphenols. Preferably used are epoxy-based curable compositions made of synthetic materials, silicone-based curable compositions made of organosilicon compounds such as methyltrimethoxysilane, and the like. In addition, these curable compositions do not require high temperatures during curing. Catalysts, curing agents or other reaction conditions Vl are not required.
? It is preferable to set the temperature at I because it can prevent bad effects on the plastic molded product.

For glass molding, known methods can be used without any particular restrictions for applying hardenability to the product.1. Ru. example
For example, a dipping method, a flow coating method, a brushing method, a rotation method, etc. are generally employed. Further, although the thickness of the cover layer is not strictly determined, it is generally 0.7μ to SOμ. Further, the curing of the curable substance may be carried out as appropriate depending on the type thereof.

As can be understood from the above explanation, according to the method of the present invention, it is possible to form a scratch-resistant coating film that has extremely good adhesion to plastic molded products, has a good surface condition, and has excellent scratch resistance. Such an effect is expressed.1. Although the mechanism by which this occurs is not yet clear, it is presumed that the surface of the glass molded product that has been subjected to plasma treatment and cleaning with a solvent has some influence on the hardening of the curable substance on the surface.

Hereinafter, examples will be given to specifically explain the present invention. However, the present invention has the following features:1. The present invention is not limited to these examples.

In the Examples and Comparative Examples, the plasma treatment was performed using a plasma reactor (Model 8%) manufactured by Yamato Scientific. In addition, various test methods were carried out using the following methods.

(1; Adhesion test (a) is a bread test; a cutter knife with a sharp tip is used to cut 100 squares of / vm x / wm on the sample surface.
After attaching each piece, commercially available sellotape was attached and the number of squares remaining when quickly peeled off was displayed.

(bl Hot water resistance test; similar to (a), the sample is
After placing wioo squares of wX/-, it was left in boiling water (gθ℃ warm water for polymethyl methacrylate VC) for 3 hours, cooled to room temperature, and commercially available sellotape was attached to the square 1 and quickly peeled off. Displayed the number of squares remaining.

(2) Koji test outside the coated film: Visually inspected as 0 if the surface of the coated film was smooth without any unevenness, and evaluated as tx if the surface of the coated film had unevenness.

Example 1 As a plastic molded product, a polydiethylene glycol bisallyl carbonate plate (!; Owax 20 sieve x small size) produced by cast polymerization was used. First, the plate-like material was washed with acetone and thoroughly air-dried to a clear state, and then subjected to plasma treatment under the conditions shown in Table 1. Next, using acetone as a solvent, it was washed using an ultrasonic cleaner for 3 minutes, air-dried again, and then washed with 20% methyltrimethoxysilane.
Parts by weight, 770 parts by weight of r-glycidoxytrimethoxysilane, 10 parts by weight of tetraethoxysilane, 0 parts by weight of O0θ3 required for hydrolysis, 4 parts by weight of isopropyl alcohol, and acetic acid as a curing catalyst) It was coated by immersion in a curable substance consisting of 71 parts of a mixture of IJum/acetic acid + /'l/θ), thoroughly air-dried at room temperature, and then heated at 130° C. for 1 hour to cure. An adhesion test and a coated appearance test were conducted on the plate-shaped body whose surface was modified in this way. result! It is also shown in Table 1.

Friend, in the above method, do not perform plasma treatment.
Comparative examples are shown below, including those that were wet and those that were not cleaned with a solvent after plasma treatment.

Example In Example 1, a plastic molded product was formed into J7 pleats by cast polymerization. 2. A copolymer of Corbinu [dar(-1methacryloxy)-ethoxy-3,5-dibutetramophenyl]-propane and styrene (hereinafter referred to as τB-styrene copolymer) with a TB/styrene weight ratio of co/3. The surface was modified in the same way as the company except that a plate-like body was used.
A round plate-like body was obtained.

This plate-shaped body was subjected to a coat group adhesion test and a coat film appearance test. The results are shown in Table V.

Also, cleaning with solvent after plasma treatment! This is also shown as a comparative example of 7t4.

Collection Example 3 As plastic molded products, commercially available polymethyl methacrylate plates and commercially available polycarbonate plates (
30w X Co O ■ × Co ■) were used, respectively. First, the plate-shaped body was washed with methanol and thoroughly air-dried to a clear state, and then plasma-treated using the conditions shown in Table 3. Next, using methanol as a solvent, washing with ultrasonic cleaning for S minutes and air drying again, methyltrimethoxysilane 01 Dobe, r-glycidoxytrimethoxysilane 1
0 parts by weight, 1 part by weight of tetraethoxysilaf, 1 part by weight of O, OS regulated hydrochloric acid required for hydrolysis, 01 parts by weight of Inglobil alcohol, and acetic acid as a curing catalyst) IJ
The sample was immersed in a curable substance consisting of 1 part by weight of a mixture of aluminum and acetic acid <1io>, and then thoroughly air-dried at room temperature and then heated at 730° C. for 1 hour to cure. However, in the case of polymethyl methacrylate, it was cured by heating at 90° C. for 2 hours. An adhesion test and VIt wiping M outside the coating film were performed on the plate-shaped body whose surface was V-modified in this manner.

The results are also shown in Table 3. Furthermore, in the method,
Comparative examples of samples that were not subjected to plasma treatment and those that were not cleaned with a bath agent after plasma treatment are also shown.

EXAMPLES According to the method of Examples 1 to 3, the plastic molded plates shown in the table were treated with VF plasma in a clear state, and then ultrasonically cleaned for S minutes in acetone or methanol according to Examples 1 to 3. After that, it was air-dried. And trimethylol triacrylate! 730°C (polymethyl In the case of methacrylate, the film was cured by heating in an oven maintained at 90° C. for 1 hour (3 hours in the case of polymethyl methacrylate).

In plasma processing, the atmospheric gas is 02(/θMJ)/^r
(JOsu) mixed gas, gas pressure 0.7 Torr.

The test was carried out under conditions of a discharge power of so low and a processing time of 1 minute. The obtained plate-shaped body was subjected to a layer density test and a coat appearance test. The results are shown in Table V.

implementation? 11. In Example Si', a precondensate consisting of 30 parts by weight of hexamethoxymethylmelamine and 41 parts by weight of dibutanediol SO as a curable substance, ammonium thiocyanate/part by weight as a curing catalyst, and isograin as a secret. A coat film was formed on a plate in the same manner except that a curable composition containing 50 parts by weight of tetrapylic alcohol was used. An adhesion test and a coating film appearance test were conducted on this plate-shaped body.

The results are shown in Table 5.

Claims (1)

[Claims] 11) f Plastic molded product vf After plasma treatment to form a modified layer on the surface, and then washing the modified layer with a solvent,
A method for surface modification of glass molded products, characterized by coating and curing with a curable substance.