JPS639526B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an acrylic resin having excellent permanent antistatic properties. Acrylic resin has a reputation for its elegant luster, outstanding transparency and weather resistance, and good mechanical properties and workability, and is used in a wide range of applications such as signboards, lighting equipment, covers, nameplates, and various decorative items. However, since acrylic resin has a strong electrostatic property, it can easily become electrostatically charged due to friction, etc., and dirt and dust may adhere to the surface, spoiling the beautiful appearance, and causing the instrument panel pointer to become misaligned. Problems may arise depending on the application. In the past, many methods have been proposed for imparting antistatic properties to such acrylic resins that are easily charged, but they can be broadly classified into the following. 1. A method of adding and kneading surfactants, fatty acid esters of polyhydric alcohols, etc. 2 A method of applying a silicone compound, etc. to the surface of a molded product. 3 A method in which a monomer having a hydrophilic group is polymerized into a resin to chemically modify the structure of the resin. First, as a method for adding and kneading a surfactant etc., for example, a method using higher fatty acid monoglyceride (Japanese Patent Application Laid-open No. 112949/1983) or a method of adding an alkyl diethanolamine derivative (Japanese Patent Publication No. 112949/1989),
53-21023) have been proposed. However, these methods have the disadvantage that the antistatic effect is easily lost by washing with water or rubbing because the surfactant etc. are not chemically bonded to the acrylic resin. Adding and kneading in large amounts not only impairs the mechanical properties of the resin, but also causes surfactants, etc. to easily bleed onto the resin surface, creating stickiness, which in turn allows dirt and dust to stick to the resin, impairing its appearance. It has disadvantages such as being damaged. JP-A-50-109944 describes that an acrylic resin is given antistatic properties by mixing a compound having a sulfonic acid group, a polyoxyalkylene glycol, and a phosphite compound. However, the compounds having a sulfonic acid group described in this publication are only exemplified by benzenesulfonic acid and para-toluenesulfonic acid, and these sulfonic acids are not chemically bonded to the acrylic resin. Because of its poor compatibility with acrylic resins, it has the disadvantage of impairing its surface gloss and transparency, which are the original characteristics of acrylic resins. Furthermore, as a method for surface coating a silicon compound, for example, a method for surface coating a solution of a partial hydrolyzate of ethyl silicate (Japanese Patent Publication No. 6533/1983) has been proposed. This surface coating method has an excellent antistatic effect and is expected to have a long-lasting effect, so it has been put into practical use to some extent, but it requires a process of applying and drying the antistatic agent to the final product, which poses a cost problem. Moreover, the coating film is damaged due to impact, friction, etc., and the antistatic effect is lost. Furthermore, as a method of chemically modifying the structure of the resin itself, for example, a method of copolymerizing polyalkylene glycol monomethacrylate with an acrylic monomer to impart an antistatic effect (Japanese Unexamined Patent Publication No. 1983-1996-1)
139516) etc. have been proposed. This method can be expected to prevent elution by chemically bonding a nonionic monomer to the resin, but
In general, the antistatic effect is low, and when a large amount of nonionic monomer is introduced, the mechanical properties and heat resistance of the resin decrease, resulting in a significant loss of properties of the acrylic resin, so this method is still insufficient. Nothing satisfactory has been found. Therefore, in view of this situation, the inventors of the present invention
Regarding a resin composition that has excellent permanent antistatic properties without impairing the original appearance characteristics of acrylic resin,
As a result of extensive studies, it was discovered that a copolymer of an acrylic monomer and a small amount of a special sulfonate satisfies this purpose, leading to the present invention. That is, the present invention provides 100 parts by weight of an acrylic monomer containing methyl methacrylate as a main component to or (However, in the formula, R ¹ is a hydrocarbon group having 1 to 18 carbon atoms, R ² is hydrogen or a methyl group, and X is a carbon number 2
~4 alkylene oxide groups, m and n are numbers from 0 to 35 on average, and M represents an alkali metal, ammonium, organic amine base, or organic quaternary ammonium base) 0.5 ~15 parts by weight, and general formula [] (However, in the formula, R ³ is an alkyl group having 1 to 18 carbon atoms,
Dissolving and polymerizing 0.5 to 5 parts by weight of an acidic phosphoric acid ester represented by an allyl group, an aryl group, an aralkyl group, an acryloxyalkyl group, a methacryloxyalkyl group, or a derivative thereof (q represents 1 or 2). A method for producing an antistatic acrylic resin characterized by the following. The present invention will be explained in detail below. The acrylic monomer mainly composed of methyl methacrylate used in the present invention refers to methyl methacrylate alone or 50% by weight or more, preferably 70% by weight or more of methyl methacrylate and other copolymerizable vinyl monomers. It is a mixture of Examples of copolymerizable vinyl monomers include ethyl methacrylate, propyl methacrylate,
Methacrylic acid esters such as butyl methacrylate, methyl acrylate, ethyl acrylate,
Propyl acrylate, butyl acrylate, 2
- Acrylic acid esters such as ethylhexyl acrylate, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, acid anhydrides such as maleic anhydride and itaconic anhydride, 2-hydroxyethyl acrylate, 2-hydroxy Propyl acrylate, tetrahydrofurfuryl acrylate, monoglycerol acrylate, 2-
Hydroxy group-containing monomers such as hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate, monoglycerol methacrylate, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetone acrylamide,
Nitrogen-containing monomers such as dimethylaminoethyl methacrylate, epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate, styrene monomers such as styrene and α-methylstyrene, ethylene glycol diacrylate, allyl Examples include crosslinking agents such as acrylate, ethylene glycol dimethacrylate, allyl methacrylate, divinylbenzene, and trimethylolpropane triacrylate. The types and amounts of copolymerizable vinyl monomers are as follows:
It can be appropriately selected depending on the properties of the desired antistatic resin. The sulfonate used in the present invention has the following general formula: or (However, in the formula, R ¹ is a hydrocarbon group having 1 to 18 carbon atoms, R ² is hydrogen or a methyl group, and X is a carbon number 2
-4 alkylene oxide groups, preferably ethylene oxide groups, m and n are number averages of 0 to 35
M represents an alkali metal, ammonium, an organic amine base, or an organic quaternary ammonium base). Specific examples thereof are represented by the following formulas (a) to (d). Preferably, in the formula, R ¹ is a hydrocarbon group having 1 to 18 carbon atoms, m and n are integers having a number average of 3 to 23, and M is an alkali metal. These sulfonate salts are required in an amount of 0.5 to 15 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of the acrylic monomer component containing methyl methacrylate as a main component. If the content is less than 0.5 parts by weight, the desired permanent antistatic property cannot be obtained, and if it is contained in excess of 15 parts by weight, the mechanical strength and water resistance of the resulting resin will decrease, resulting in poor practicality. So I don't like it. Note that water resistance means that the resin composition does not deteriorate in surface gloss, antistatic property, or transparency when it comes into contact with water. Next, the acidic phosphoric acid ester used in the present invention has the general formula [] (However, in the formula, R ³ is an alkyl group having 1 to 18 carbon atoms,
Compounds represented by an allyl group, an aryl group, an aralkyl group, an acryloxyalkyl group, a methacryloxyalkyl group, or a derivative thereof (where q represents 1 or 2), such as monomethyl phosphate, dimethyl phosphate, monoethyl phosphate , diethyl phosphate, monopropyl phosphate, dipropyl phosphate, monobutyl phosphate, dibutyl phosphate, monohexyl phosphate, dihexyl phosphate, mono 2-ethylhexyl phosphate, di(2-ethylhexyl) phosphate, monooctyl Phosphate, dioctyl phosphate, monodecyl phosphate, didecyl phosphate, monotridecanol phosphate, ditridecanol phosphate, monostearyl phosphate, distearyl phosphate, monooleyl phosphate, dioleyl phosphate, Examples include monophenyl phosphate, diphenyl phosphate, nonylphenyl phosphate, di(nonylphenyl) phosphate, mono(2-hydroxyethyl) methacrylate phosphate, di(2-hydroxyethyl) methacrylate phosphate, and the like. Among these, monoethyl phosphate, diethyl phosphate, monopropyl phosphate, dipropyl phosphate, monobutyl phosphate, and dibutyl phosphate can be particularly preferably used. The acidic phosphoric acid ester is contained in an amount of 5 parts by weight or less per 100 parts by weight of the acrylic monomer whose main component is methyl methacrylate. Preferably, it is used in a range of 0.5 to 5 parts by weight. If it is contained in an amount exceeding 5 parts by weight, the mechanical strength of the resulting resin may be lowered or it may bleed onto the resin surface, which is not preferable. Acidic phosphoric acid ester has the effect of improving water resistance by containing it. Furthermore, additives such as heat stabilizers, ultraviolet absorbers, colorants, plasticizers, and various fillers may be mixed with the monomers as necessary, as long as the amount is within the range that achieves the purpose of the present invention. It can be used as In the present invention, an acrylic monomer containing methyl methacrylate as a main component has the general formula []
Or, the sulfonate represented by [], the acidic phosphate ester, and other additives as necessary are mixed and dissolved in advance, and a well-known polymerization method such as bulk polymerization or emulsion polymerization is carried out in the presence of a radical polymerization initiator. to make a resin. Among acidic phosphoric acid esters, polymerizable ones such as mono(2-hydroxyethyl) methacrylate phosphate and di(2-hydroxyethyl) methacrylate phosphate are copolymerized and contained. The resin obtained in this way has extremely excellent antistatic properties without impairing the original characteristics of the resin, such as transparency, surface gloss, mechanical properties, weather resistance, and processability. are doing. Moreover, the antistatic effect hardly changes with washing with water or friction, and also shows excellent performance with almost no change over time, making it extremely practical. Among the sulfonate-containing monomers that have been conventionally recognized to have an antistatic effect, those that are difficult to dissolve in methyl methacrylate monomers, such as sodium allylsulfonate, sodium methacrylsulfonate, sodium vinylsulfonate, and alkenyl aromatics. When sodium sulfonate, sodium methacryloxyalkyl sulfonate, etc. are included in an acrylic resin whose main component is methyl methacrylate, their affinity with the resin is low and transparency is significantly impaired, which is a characteristic of acrylic resins. The quality of the surface gloss is significantly reduced, making it impractical and not suitable for the purpose of the present invention. The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples. Note that parts in the examples indicate parts by weight. Example 1 100 parts of methyl methacrylate and formula 2 parts of the sulfonate represented by
0.2 parts of lauroyl peroxide was added as a polymerization initiator. Pour this mixture into a polyvinyl chloride gasket and
Injected into a polymerization cell consisting of two glass plates and heated to 67°C.
for 6 hours, then heated and polymerized at 110℃ for 1 hour.
A colorless and transparent resin plate with a thickness of mm and a good surface gloss was obtained. The obtained resin plate was subjected to the following tests, and a general methacrylic resin plate (manufactured by Sumitomo Chemical Industries, Sumipex) was used.
000), and the results are shown in Table 1. (1) Antistatic property ○A Surface resistivity: After being left in the standard conditions of 23℃ and 50% humidity for 3 days, it was measured using a super megohmmeter (manufactured by Toa Denpa Kogyo, model SM-10E) in the same atmosphere. It was measured. ○B Half-life: Using a static meter (manufactured by Shishido Shokai), after applying a voltage of 10 KV in the same atmosphere as ○B, the applied voltage was set to zero and the time until the charged voltage was reduced by half was measured. (2) Transparency Total light transmittance in accordance with ASTM D-1003,
The haze value was measured.

【table】

[Table] From Table 1, it can be seen that the obtained resin plate has excellent transparency like a general methacrylic resin plate, and has much better antistatic properties than a general methacrylic resin plate. In addition, the obtained resin plate has a heat deformation temperature of 105℃,
The tensile strength at break was 722 Kg/cm ² , which did not impair the heat resistance and mechanical properties of general methacrylic resin plates. In addition, the obtained resin plate was immersed in water at 30°C for 2 days, then air-dried, and its transparency and antistatic properties were measured.The total light transmittance was 92.5%, and the haze value was 0.4.
%, and the antistatic properties showed a surface resistivity of 5×10 ¹⁰ Ω, a half-life of 1 second, and the effect hardly changed even when immersed in water. Examples 2 to 4, Comparative Examples 1 to 5 A 3 mm thick resin plate was obtained in the same manner as in Example 1, except that the types and amounts of the sulfonate and acidic phosphate ester were changed as shown in Table 2. Ta. The transparency, antistatic properties, mechanical strength, and water resistance of the obtained resin plate were measured in the same manner as in Example 1, and the results are shown in Table 3.

【table】

[Table] ｜
b○ NaO ₃ S−CHCOO(CH ₂ CH ₂ O) ₉ CH ₂ CH=CH ₂

[Table] (Note) Water resistance measurement method
After being immersed in water at 30°C for 2 days and air-dried, transparency and antistatic properties were measured.
Example 5 100 parts by weight of a monomer consisting of 95 parts of methyl methacrylate and 5 parts of tetrahydrofurfuryl methacrylate, 0.5 parts of potassium methacryl lauryl sulfosuccinate and the formula After mixing and dissolving 2.5 parts of the monomer represented by, 1.5 parts of AP-3 (manufactured by Daihachi Kagaku Kogyo, a mixture of monoisopropyl phosphate and diisopropyl phosphate) and AC Black (manufactured by Tokyo Ink), A 3 mm thick resin plate was obtained in the same manner as in Example 1 by adding 0.2 part of lauroyl peroxide. The obtained resin plate was a glossy black resin plate, and the surface specific resistance was measured in the same manner as in Example 1.
It had an excellent antistatic property with a resistance of 1.2×10 ¹⁰ Ω and a half-life of 1 second. In addition, the obtained resin plate was immersed in water at 30°C for 2 days and then air-dried to examine the surface appearance and antistatic properties of the resin plate, and it was found that the surface maintained a black and glossy surface. It had an excellent resistivity of 2.4×10 ¹⁰ Ω, a half-life of 1 second, and an antistatic effect that hardly changed when immersed in water.

Claims (1)

[Scope of Claims] 1. 100 parts by weight of an acrylic monomer containing methyl methacrylate as a main component and the general formula or (However, in the formula, R ¹ is a hydrocarbon group having 1 to 18 carbon atoms, R ² is hydrogen or a methyl group, and X is a carbon number 2 to 18.
4, m and n are numbers from 0 to 35 on average, and M is an alkali metal, ammonium, an organic amine base, or an organic quaternary ammonium base).
0.5 to 15 parts by weight, and general formula [] (However, in the formula, R ³ is an alkyl group having 1 to 18 carbon atoms,
Dissolving and polymerizing 0.5 to 5 parts by weight of an acidic phosphoric acid ester represented by an allyl group, an aryl group, an aralkyl group, an acryloxyalkyl group, a methacryloxyalkyl group, or a derivative thereof (q represents 1 or 2). A method for producing an antistatic acrylic resin characterized by: