JP3450160B2 - Method for producing antistatic polycarbonate resin sheet - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an antistatic polycarbonate resin sheet. More specifically, it relates to a method for producing an antistatic polycarbonate resin sheet in which a melamine-based cured film exhibiting excellent antistatic properties is firmly adhered.

[0002]

2. Description of the Related Art Polycarbonate resins are widely used for electric parts, building material parts, automobile parts, etc. because they are excellent in transparency, heat resistance, heat and humidity resistance, workability and mechanical strength. Polycarbonate resin sheet with a cured film made of
Various window materials and side walls due to the fact that they are easy to thermoform and that it is easy to add non-reflective coating agents made of fluorine compounds, infrared cut agents, electromagnetic wave shielding agents, antifouling agents, etc. It is widely used in the fields of boards and displays. In recent years, it has begun to be used in the field of front panels of projection televisions and plasma displays by taking advantage of such characteristics.
However, when a polycarbonate resin sheet provided with a cured film made of a melamine-based resin is used for such a front plate, there arises a problem that an image becomes hard to see due to adhesion of dust and the like.

Various proposals have heretofore been made regarding methods for preventing the adhesion of dust and dirt. For example, dip a polycarbonate resin sheet in a tetrahydrofuran solution,
Then, a method of immersing in a tetrahydrofuran / cyclohexane solution in which LiAlH ₄ is dispersed, further immersing in a hydrochloric acid aqueous solution, followed by washing with water and drying (JP-A-58-79028), an organic solvent for dissolving or swelling a synthetic resin is used. A method has been proposed in which an electrically conductive surface layer is formed on the surface of this synthetic resin molded article by treatment with an electrolyte solution (JP-A-63-61031). However, with a polycarbonate resin sheet provided with a cured film made of a melamine resin, it is difficult for chemical treatment to proceed sufficiently, and it is difficult to obtain the desired antistatic effect.

On the other hand, a method in which an antistatic agent having at least three methyl groups in a phosphorus atom directly or via oxygen is mixed with a coating material and applied to a sheet and dried (JP-A-5-5).
Japanese Patent No. 1575) has been proposed. However, when an antistatic agent is added to the melamine-based resin coating composition, when it is applied to a polycarbonate resin sheet, an adverse effect of poor adhesion occurs, and effective antistatic properties cannot be obtained. Further, as a method of preventing the adhesion of dust and dust, a method of spraying a commercially available antistatic spray or a method of wiping the screen with a solution of a surfactant is known,
In these methods, the antistatic effect is lost with the passage of time, and therefore, the appearance of a polycarbonate resin sheet provided with a cured film made of a melamine resin having durability and antistatic property has been desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an antistatic polycarbonate resin sheet in which a cured film made of a melamine resin exhibiting excellent antistatic properties is firmly adhered. The inventors of the present invention have an interface that is easily dissolved in a melamine-based resin coating, retains excellent adhesion even after being applied to a polycarbonate resin sheet and cured, and exhibits an excellent antistatic effect in which dust and dust do not adhere. As a result of various studies on the active agent, it was found that there is an effect on the incorporation of a specific amount of the cationic surfactant, and the present invention has been accomplished.

[0006]

The present invention SUMMARY OF THE INVENTION, when at least a polycarbonate resin sheet by applying a melamine resin coating on one surface to form a cured film, the cured film 1 m ² per a cationic surfactant 0. A melamine resin paint containing 003 to 0.5 g is applied, and the thickness of the cured film is 1
10 μm, the surface resistance of the formed cured film is 1
The method for producing an antistatic polycarbonate resin sheet is characterized by setting the resistance to 0 ¹⁴ Ω or less.

The polycarbonate resin referred to in the present invention is
It is an aromatic polycarbonate resin obtained by reacting a dihydric phenol with a carbonate precursor. As the dihydric phenol used here, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A) is mainly used, but a part or all of it may be replaced with another dihydric phenol. . Other dihydric phenols include, for example, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-). Examples thereof include 3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone and the like. Examples of the carbonate precursor include phosgene, diphenyl carbonate, and bischlorophenol of the above dihydric phenols.
And di-p-tricarbonate, and phosgene and diphenyl carbonate are particularly preferable. The polymerization degree of the polycarbonate resin is preferably about 15,000 to 35,000, which is usually expressed as a viscosity average molecular weight.

Any method can be used for producing such a polycarbonate resin, but for example, a solution method using phosgene as a carbonate precursor or a melting method using diphenyl carbonate as a carbonate precursor is preferably used.

The solution or phosgene method using phosgene is carried out in the presence of an acid binder and an organic solvent. An alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine is used as the acid binder, and a halogenated hydrocarbon such as methylene chloride or chlorobenzene is used as the solvent. A catalyst such as a tertiary amine or a quaternary ammonium salt may be used to accelerate the reaction. The reaction temperature is usually 0 to 40 ° C., and the reaction time is several minutes to 5 hours.

Further, in the melting method using diphenyl carbonate, that is, the transesterification method, the dihydric phenol component in a predetermined ratio is stirred while heating with diphenyl carbonate in an inert gas atmosphere to distill the alcohol or phenols produced. Method. The reaction temperature will differ depending on the boiling point of the alcohol or phenol to be produced, but is usually in the range of 120 to 300 ° C. The reaction is completed by depressurizing from the initial stage while distilling off the produced alcohol or phenols. Further, a usual transesterification catalyst can be used to accelerate the reaction.

In the production of such a polycarbonate resin, if necessary, a suitable molecular weight regulator, a branching agent for improving processability, a stabilizer such as phosphite ester, phosphate ester, phosphonate ester, etc., tetrabromobisphenol A , A low molecular weight polycarbonate such as tetrabromobisphenol A, a flame retardant such as decabromodiphenol, a coloring agent, a lubricant and the like can be added.

The polycarbonate resin sheet used in the present invention is produced by any method using the above polycarbonate resin, but is usually produced by a melt extrusion method. The thickness of the polycarbonate resin sheet is not particularly limited, but if it is too thin, the flexure will be large, and if it is too thick, the mounting jig will be unnecessarily large because of the weight.
The range of 10 mm is preferable.

The melamine resin coating used in the present invention is a melamine resin and a glycol as a crosslinking agent crosslinked with a curing agent, and the melamine resin in the present invention means methylated methylolmelamine and propyl. Methylol melamine, butylated methylol melamine, melamine resin such as isobutyl methylol melamine alone, or a mixture of a modifier such as an acrylic resin, polyether, polyester, silicone resin, etc. within a range that does not impair the characteristics of the present invention. is there.

The method for preparing the melamine-based resin coating material used in the present invention is as follows: a short-chain glycol such as ethylene glycol, diethylene glycol, butanediol, hexanediol, etc. 1 or 2 or more of these are blended, and then p-toluenesulfonic acid, oxalic acid, maleic acid or the like is selected as a curing agent, and a lower alcohol such as methanol, ethanol, isopropyl alcohol or isobutyl alcohol, ethylene is selected as a solvent. After adding cellosolves such as glycol monomethyl ether and diethylene glycol monobutyl ether, and hydrocarbons such as toluene and xylene, a cationic surfactant is added. It is also possible to mix various additives as needed. For example, it is an ultraviolet absorber, a leveling agent, an antifoaming agent, or the like.

The amount of the cross-linking agent and the curing agent to be blended in the melamine-based resin coating material is appropriately determined depending on the purpose. Usually, in the cross-linking agent, the functional group of the melamine resin and the functional group of the cross-linking agent are equimolar amounts. Is used as a guide. The amount of curing agent is 1 with respect to the amount of melamine resin.
10 to 10% by weight, preferably 2 to 7% by weight.

In the present invention, a cationic surfactant is used as an antistatic agent. The cationic surfactants provided antistatic effects, but the ethylene oxide-type nonionic surfactants and fluorine-based anionic surfactants did not. Examples of such cationic surfactants include aliphatic amine salts, quaternary ammonium salts, alkylpyridinium salts, and the like.
Higher grade ammonium salts can be preferably used. Such a fourth
Examples of the primary ammonium salts include benzyl type, methosulfate type, ethanol addition type and alkylene glycol chain containing type.

Typical examples of such a quaternary ammonium salt type cationic surfactant include compounds having the following structural formulas.

[0018]

[Chemical 1]

[0019]

[Chemical 2]

[0020]

[Chemical 3]

[0021]

[Chemical 4]

[Where n is a number from 1 to 20]

[0023]

[Chemical 5]

[However, both m and n are numbers from 1 to 20 and may be the same or different from each other]

The amount of the cationic surfactant blended is such that the surface resistance value of the cured film formed on the polycarbonate resin sheet becomes 10 ¹⁴ Ω or less, but if it is too large, the adhesion between the cured film and the polycarbonate resin sheet since sex is not easily maintained, the cured film 1 m ² per 0.00
The range of 3 to 0.5 g is preferable.

No special method is required to form a cured film of a melamine-based resin in which a cationic surfactant is mixed in a polycarbonate resin sheet, and a usual method for applying a melamine-based resin coating, for example, a dipping method is used. It is applied to a polycarbonate resin sheet by a spray coating method or the like, and is usually 0.5 to 100 ° C. to 130 ° C. by hot air drying or infrared drying.
It may be dried by heating for 1 hour. Even if the cured film is formed on only one surface depending on the application of the polycarbonate resin sheet,
You may form on both surfaces. The thickness of the cured film is 1-10 μm
Is preferred. When the thickness of the cured film is less than 1 μm, it becomes difficult to withstand abrasion and friction, and depending on the amount of the cationic surfactant added, a sufficient antistatic effect may not be exhibited. If it is thicker than 10 μm, the effect is saturated sooner, and it is not necessary to further increase the thickness. Further, in forming the cured film, various pretreatments can be performed in order to enhance the adhesion between the cured film and the polycarbonate resin sheet. For example, after treating the surface of the polycarbonate resin sheet with a treatment such as corona discharge or ultraviolet irradiation or applying a mixed solution of monoethanolamine and isobutanol, 9
It is also possible to enhance the adhesion between the cured coating and the polycarbonate resin sheet by a method of heating and drying at 0 to 120 ° C. for several minutes.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be further described below with reference to Examples. The parts in the examples are parts by weight, and the evaluation was performed by the following method.

(1) Surface resistance: JIS K 6 using a hyper-insulator [SME-8000 manufactured by Toa Denpa Kogyo KK]
The surface resistance was measured by the method of 911.

(2) Film thickness of cured film: The film thickness was measured with a refractive index of 1.55 using an optical interference film thickness meter [MCPD-1000 manufactured by Otsuka Electronics Co., Ltd.].

(3) Adhesion of cured film: JIS K 5
Adhesion was measured by the cross-cut tape method according to 400.

(4) Adhesion of dust: Adhesion of dust was visually evaluated by leaving it in a room for 10 days. When there is almost no adhesion of dust, it is indicated by ◯, and when there is much dust, it is indicated by Δ.

(5) Effect Wet heat test of coating: temperature 60
After left in an atmosphere of ℃ and relative humidity of 95% RH for 168 hours, the adhesion of the cured film (3) was measured.

[Example 1] (A) Preparation of melamine-based resin paint Methylated methylol melamine [Cymel 350 manufactured by Mitsui Cyanamide Co., Ltd.] 100 parts 1,6-hexanediol (reagent) 70 parts Maleic acid (reagent) 5 Part Isopropyl alcohol (reagent) 150 parts Isobutyl alcohol (reagent) 320 parts Ethylene glycol monobutyl ether (reagent) 25 parts are mixed to obtain a melamine-based resin paint, and 100 parts of this melamine-based resin paint is mixed with a cationic surfactant. 0.01 part of a certain polyoxypropylene methyldiethyl ammonium chloride [Adecacol CC-15 manufactured by Asahi Denka Co., Ltd.] was added and mixed to prepare a melamine-based resin paint containing a surfactant.

(B) Production of Antistatic Polycarbonate Resin Sheet The melamine-based resin coating material for coating obtained in (A) is applied to a thickness of 2 m.
m, width 100 mm, length 200 mm polycarbonate resin sheet [Panlite Sheet PC11, Teijin Chemicals Ltd.
11] by a flow coating method, allowed to stand at room temperature for 10 minutes, and then heat-dried for 60 minutes in a hot air circulation dryer at 120 ° C. to have a cured film of 6.3 μm, and a surfactant in the cured film. To obtain an antistatic polycarbonate resin sheet having an amount of 0.003 g / m ² . The surface resistance of the obtained antistatic polycarbonate resin sheet is 2.1 × 10 ¹³ Ω.
The adhesion between the polycarbonate resin sheet and the formed cured coating was also good. In the adhesion test after the wet heat test, the evaluation score was 8 points, and there was no problem in practical use. When this antistatic polycarbonate resin sheet was left indoors for 10 days, there was almost no adhesion of dust, and it was a very useful polycarbonate resin sheet as a front plate of a projection television or the like.
The results are shown in Table 1.

[Examples 2 to 4 and Comparative Examples 1 to 4] The same melamine resin coating material as in Example 1 was mixed with the surfactants shown in Table 1 in the amounts shown in Table 1 to blend the surfactants. A melamine resin coating material was prepared and an antistatic polycarbonate resin sheet was produced in the same manner as in Example 1, and the results are shown in Table 1.

[0036]

[Table 1]

The symbols showing the kinds of the surfactants in Table 1 are as follows. A: ADEKA COL CC-15 (quaternary ammonium salt type cation type) manufactured by Asahi Denka Co., Ltd. B; Electrostriper QN (quaternary ammonium salt type cation type) manufactured by Kao Corporation C: ADEKA Pluronic TR-702 (Non-ion system) Asahi Denka Kogyo Co., Ltd. D; F-top EF-204 (Anion system) Mitsubishi Materials Co., Ltd.

[0038]

EFFECTS OF THE INVENTION According to the present invention, it is difficult for dust and dirt to adhere, and is excellent in antistatic property useful in the field of automobile / vehicle window materials, construction window materials, road side wall boards and display fields such as televisions and personal computers. It becomes possible to provide a polycarbonate resin sheet in which a melamine-based cured film that exhibits
The industrial effect it produces is exceptional.

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Claims (4)

(57) [Claims] 1. A melamine containing a cationic surfactant in an amount of 0.003 to 0.5 g per 1 m ² of the cured film when a cured film is formed by applying a melamine resin coating on at least one surface of a polycarbonate resin sheet. A method for producing an antistatic polycarbonate resin sheet, which comprises applying a resin coating composition, the cured film has a thickness of 1 to 10 μm, and the surface resistance of the formed cured film is 10 ¹⁴ Ω or less. 2. The method for producing an antistatic polycarbonate resin sheet according to claim 1, wherein the cationic surfactant is a quaternary ammonium salt type cationic surfactant. 3. A melamine-based resin coating is a melamine resin and
And glycols as a crosslinking agent were crosslinked with a curing agent
The method for producing an antistatic polycarbonate resin sheet according to claim 1, wherein 4. The thickness of the polycarbonate resin sheet is
It is 1-10 mm, The manufacturing method of the antistatic polycarbonate resin sheet of any one of Claims 1-3.