JPH0478669B2 - - Google Patents

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to an antistatic agent, and more specifically, an antistatic agent using a vinylpyridine-based comb copolymer, which is applicable to molding resins. This invention relates to an antistatic agent that has excellent durability compared to other antistatic agents.

"Prior Art" Molding materials used in the manufacture of housings and parts for home appliances such as televisions, radios, electric refrigerators, and office equipment such as typewriters, word processors, and personal computers include polymethyl methacrylate, ABS resin, AS resin, polyvinyl chloride, a composition consisting of polyphenylene ether and rubber-modified polystyrene (so-called Noryl resin), etc. (hereinafter referred to as "thermoplastic resin for molding") are widely used. These thermoplastic resins for molding have excellent electrical insulation properties and are therefore excellent as molding materials for the above-mentioned casings, etc., but they have the drawback of being easily charged with static electricity. When charged with static electricity, it attracts dirt, dust, etc., which not only impairs the appearance, but also causes problems such as poor contact at the contacts of switches.

Traditionally, to solve these problems,
Antistatic ability has been imparted by applying a known antistatic agent to the surface of a molded article, or kneading a known antistatic agent into a thermoplastic resin for molding. As these known antistatic agents, substances are generally used that have the function of imparting hydrophilicity to a thermoplastic resin for molding, thereby lowering the electrical resistance of the resin and preventing static electricity charging.

Examples of these known antistatic agents that have been used in the past include fatty acid esters of polyethylene glycol, surfactants such as alkylbenzene sulfonates, and pyridinium salts of random copolymers of vinyl pyridine and methyl methacrylate. Copolymer, copolymer of acrylamide and acrylic acid ester, comb-shaped copolymer containing SO ₃ M (M=alkali metal) group and/or polyethylene oxide group (Japanese Patent Application Laid-Open No. 59-230057) Hydrophilic polymers such as

"Problems to be Solved by the Invention" However, in the method of applying a known antistatic agent to the surface of a molded product, the antistatic agent peels off due to changes over time or washing, etc., and the antistatic effect is lost. The problem was that the product was easily broken and the productivity of the molded product was low because an antistatic agent coating process was required separately from the molding process.

In addition, the method of kneading a known antistatic agent into a thermoplastic resin for molding solves problems such as peeling off of the antistatic agent and reduced productivity, but it also prevents static electricity from changing over time and due to surface stains. Problems such as decreased effectiveness were not sufficiently improved. That is, the sustainability of the antistatic effect was not sufficiently improved. This is because these conventional antistatic agents are generally relatively low-molecular-weight compounds with polar groups, so they have poor compatibility with thermoplastic resins for molding, and when incorporated in large amounts, they cause a decline in the physical properties of the resin. Therefore, it was not possible to mix in a sufficient amount to obtain the necessary antistatic effect and its sustainability. Incidentally, the comb-shaped copolymer as described in JP-A No. 59-230057 has a so-called micro phase separation structure.
Volume 297-308 (1984)", even if it has a polar group,
Although the compatibility was high, the sustainability of the antistatic effect was still not sufficiently improved.

The present inventors have arrived at the present invention as a result of intensive research aimed at obtaining an antistatic agent with excellent durability.

"Means for Solving the Problems" The above object of the present invention is that the number average molecular weight is 1×
It consists of a polymer part consisting of vinyl monomer residues of 10 ³ to 2 × 10 ⁴ , and furthermore, the polymer part is
At least one selected from the group consisting of 20 to 80% by weight of a high molecular weight monomer residue having a polymerizable vinyl group at one end, a vinylpyridine monomer residue, and a vinylpyridinium monomer residue. 80-20% by weight of species monomer residues and 0 hydrophilic monomer residues
This can be achieved by using an antistatic agent characterized by using a vinylpyridine-based comb copolymer containing ~60% by weight.

In the present invention, the "high molecular weight monomer" used for producing the comb copolymer refers to a polymer compound having a polymerizable vinyl group at one end of the polymer chain.

In the present invention, the term "comb copolymer" refers to a copolymer consisting of the above-mentioned high molecular weight monomer residues and monomer residues copolymerizable with the high molecular weight monomers.

The polymer portion consisting of vinyl monomer residues in the present invention has a number average molecular weight of 1×10 ³ to 2×10 ⁴ ,
Preferably, the polymer portion consists of a vinyl monomer residue in the range of 3×10 ³ to 1.5×10 ⁴ , and the polymer portion is a compound having a polymerizable vinyl group at one end thereof. It is.

When the number average molecular weight of the polymer portion of the high molecular weight monomer is less than 1×10 ³ , microphase separation of the obtained comb-shaped copolymer is difficult to occur, and as a result, it is difficult to cause microphase separation from the thermoplastic resin for molding. This is not preferred because the compatibility decreases. Furthermore, if the above number average molecular weight exceeds 2×10 ⁴ , the solubility of the high molecular weight monomer in organic solvents will decrease and the viscosity of the obtained solution will also increase. It is difficult to produce a comb-shaped copolymer using this method, so it is not preferred.

The high molecular weight monomer is suitably one in which the polymer portion consists of vinyl monomer residues.

If the above polymer part is made of monomer residues other than vinyl monomer residues, for example, if it is made of a polycondensation polymer part such as polyester, polyether, or polyamide, molding is possible. This is not preferred because of its low compatibility with the thermoplastic resin for use and the lack of a suitable solvent for producing the comb copolymer.

Vinyl monomer residues include esters of acrylic acid or methacrylic acid and alcohols having 1 to 10 carbon atoms, styrene, α-methylstyrene, o-, m-, or p-vinyl Examples include toluene, a mixture of o-, m-, and p-isomers of vinyltoluene, the halogenated styrene, and residues such as α- or β-vinylnaphthalene.

The high molecular weight monomer residue of the comb copolymer of the antistatic agent of the present invention is preferably one in which the polymer portion consists of a residue of an ester of acrylic acid or methacrylic acid, particularly methyl methacrylate. This is because a high molecular weight monomer can be produced by a radical polymerization method suitable for industrial production.

The high molecular weight monomer needs to have one polymerizable vinyl group at the end of its molecular chain. If it does not contain a polymerizable vinyl group, it cannot be copolymerized with a monomer such as vinylpyridine, and if it contains two or more polymerizable vinyl groups, it cannot be copolymerized with a monomer such as vinylpyridine. This is not preferred because it causes crosslinking.

The polymerizable vinyl group may be any group as long as it can be copolymerized with other copolymers constituting the comb copolymer of the present invention.

As the polymerizable vinyl group, an acrylic group, a methacrylic group, or a functional group containing an acrylic group or a methacrylic group can be easily introduced during the production of a high molecular weight monomer, and can be copolymerized. It is preferable because it is excellent.

The polymer portion of the high molecular weight monomer is produced by radical polymerization or anionic polymerization.

In the case of radical polymerization, use of persulfates, organic peroxides such as benzoyl peroxide and di-t-butyl peroxide, azo compounds such as azobisisobutyronitrile, and other commonly used radical initiators, or , a vinyl monomer is polymerized by thermal polymerization to form a polymer portion of a high molecular weight monomer. At that time, a chain transfer agent is used to adjust the number average molecular weight, and by using a compound having a reactive functional group such as a carboxyl group or a hydroxyl group as a chain transfer agent, the polymerizable vinyl group can be quantified. It can be introduced as follows. That is, the chain transfer agent binds to the terminal end of the polymer moiety and terminates the polymerization, but as a result, the reactive functional group bound to the chain transfer agent binds to the terminal end of the high molecular weight monomer. A polymeric portion is formed. A high molecular weight monomer is obtained by reacting the obtained polymer portion having a reactive functional group with a compound having a polymerizable vinyl group.

Examples of the chain transfer agent having a reactive functional group include hydroxyalkyl mercaptans such as hydroxyethyl mercaptan and hydroxypropyl mercaptan (the number of carbon atoms in the alkyl group is preferably in the range of 1 to 12), thioglycolic acid, propane sultone, etc. can be mentioned.

In addition, examples of the compound having a polymerizable vinyl group include acrylic acid, methacrylic acid, glycidyl acrylate, glycidyl methacrylate, and monoesters of acrylic acid and methacrylic acid with polyethylene glycol or alkylene glycol (degree of polymerization 1 to 70). Can be mentioned.

When producing a high molecular weight monomer by an anionic polymerization method, an alkyl alkali metal compound such as an alkyl lithium compound such as n-butyl lithium or sec. butyl lithium is used as a polymerization initiator.
In this case, the number average molecular weight of the polymer portion can be controlled by the amount of initiator used.

According to anionic polymerization, a so-called living polymer is obtained in which an alkali metal such as lithium is bonded to the end of the polymer moiety, and a halogen compound containing a desired polymerizable vinyl group, such as acryl chloride or methacryl chloride, is added to this. , vinyl chloride, etc., a high molecular weight monomer can be obtained.

The monomer residue copolymerized with the high molecular weight monomer to form the comb copolymer is selected from the group consisting of vinylpyridine monomer residues and vinylpyridinium salt monomer residues. At least one monomeric residue is suitable. This is due to the long-lasting antistatic effect of the comb copolymer containing vinylpyridinium monomers, and the fact that these monomers are mixed with high molecular weight monomers and other materials during the production of the comb copolymer. This is because it is easy to copolymerize with a copolymer. Furthermore, vinylpyridine monomer residues can be easily converted to vinylpyridinium monomer residues by the method described below.

As vinylpyridine monomer residues, 4-vinylpyridine and 2-vinylpyridine residues are preferred, but 3-vinylpyridine, 2-methyl-5
-Residues such as derivatives of the above-mentioned vinylpyridine isomers in which the pyridine nucleus is substituted with an alkyl group having 1 to 5 carbon atoms, such as vinylpyridine, are also included.

As the vinyl pyridinium salt monomer, the above vinyl pyridine monomer residue can be replaced with a mineral acid such as hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid or a salt thereof, a carboxylic acid such as acetic acid or a salt thereof, methyl Examples include those obtained by pyridinium chloride using a vinylpyridinium chloride reagent such as alkyl halides having 1 to 5 carbon atoms such as chloride, methyl bromide, ethyl chloride, and ethyl bromide.

When producing a comb-shaped copolymer containing a vinylpyridinium salt monomer residue, copolymerization may be performed using a vinylpyridinium salt monomer synthesized in advance; The monomer may be unstable as a monomer, so after copolymerizing a high molecular weight monomer, a vinylpyridine monomer, and, if necessary, a hydrophilic monomer, It is more preferable to react the obtained comb-shaped copolymer with a pyridinium chloride reagent such as the above-mentioned hydrochloric acid to convert the vinylpyridine monomer residue into pyridinium chloride because production is easier.

The vinyl pyridine comb copolymer containing no vinyl pyridinium salt monomer residue is dissolved in a polar solvent such as dimethylformamide or nitromethane, or is formed into pellets or
The vinylpyridine monomer residue contained in the comb copolymer can be converted into pyridinium salt by reacting it with a liquid or gaseous pyridinium chloride reagent in powder form. Also,
After blending with the thermoplastic resin for molding, pyridinium chloride may be formed.

The comb-shaped copolymer of the present invention improves the antistatic effect by containing a hydrophilic monomer residue.

In the present invention, a hydrophilic monomer residue refers to a vinyl monomer residue having a hydrophilic group.

Hydrophilic groups include carboxyl groups, amide groups, lactone groups, lactam groups, polyether groups,
Examples include alcoholic hydroxyl groups.

Specific examples of hydrophilic monomer residues include acrylic acid, methacrylic acid, or alkali metal salts or amide derivatives thereof, or those having a degree of polymerization of 1 to 70.
esters with polyethylene glycols in the range of
and residues such as p-styrene sodium sulfonate, ethylene sodium sulfonate, and 2-sulfoethyl methacrylate.

The content of each monomer residue contained in the comb copolymer of the present invention is 20 to 80% by weight of high molecular weight monomer residue, preferably 40 to 60% by weight, and vinylpyridine monomer residue. 80 to 20% by weight, preferably 50 to 30% by weight, of at least one monomer residue selected from the group consisting of vinylpyridinium salt monomer residues and hydrophilic monomer residues 0-60% by weight,
Preferably, 10 to 30% by weight is appropriate.

If the content of high molecular weight monomer residue is less than 20% by weight, the compatibility between the comb copolymer and the thermoplastic resin for molding will decrease, and if it exceeds 80% by weight, the antistatic effect will decrease. So I don't like it.

Antistatic effect when the content of at least one monomer residue selected from the group consisting of vinylpyridine monomer residues and vinylpyridinium salt monomer residues is less than 20% by weight. If it exceeds 80% by weight, the compatibility with the thermoplastic resin for molding will decrease, which is not preferable.

As the content of the hydrophilic monomer residue increases, the antistatic effect improves, but if it exceeds 60% by weight, the compatibility with the thermoplastic resin for molding and the sustainability of the antistatic effect decrease, which is not preferable.

The comb copolymer in the present invention can be produced by a radical polymerization method. In that case, the solvent is dimethylformamide, diethylene glycol, methyl ethyl ketone, dimethyl ether,
Using a polar organic solvent such as tetrahydrofuran,
It is preferable to copolymerize each desired monomer mixture using an azo compound, an organic peroxide, such as azobisisobutyronitrile, lauryl peroxide, etc., as an initiator.

The obtained comb-shaped copolymer is used by blending with a thermoplastic resin for molding. At that time, when using a comb-shaped copolymer that does not contain vinylpyridinium salt monomer residues, after blending, the resulting composition or a molded article molded using the composition contains pyridinium. It can be treated with a chlorinating reagent to impart an antistatic effect.

The blending ratio of the comb-shaped copolymer of the antistatic agent of the present invention and the thermoplastic resin for molding is appropriately determined as necessary, but the vinyl pyridine monomer residue and vinyl The total content of pyridinium salt monomer residues is preferably 1 to 10% by weight. In this case, by blending another hydrophilic resin, such as a copolymer of a hydrophilic monomer and methyl methacrylate, the antistatic effect can be further improved. Furthermore, the comb copolymer of the antistatic agent of the present invention may be used by coating it on the surface of a thermoplastic resin molded article.

"Effects of the present invention" The comb-shaped copolymer of the antistatic agent of the present invention contains a high molecular weight monomer residue component that is highly compatible with the thermoplastic resin for molding, so it reduces the physical properties of the resin. Furthermore, since it contains at least one monomer residue component selected from the group consisting of vinylpyridine monomer residues and vinylpyridinium monomer residues, it provides an excellent antistatic effect. It can significantly improve the sustainability of its antistatic effect, so it has great industrial utility value.

〔Example〕

The present invention will be specifically explained based on Examples and Comparative Examples.

In each of the following Examples and Comparative Examples, the antistatic effect was evaluated based on surface resistance and charging half-life.

For surface resistance in the range less than 10 ⁷ Ω/cm, use Sanwa Keiki Seisakusho's Digital Multimeter, 8000 ZM.
Using a sample piece of 8 cm x 8 cm x 1 mm, the resistance value was measured at an inter-electrode distance of 5 cm and was expressed as the value divided by the above-mentioned inter-electrode distance (5 cm). In addition, in order to reduce the influence of contact resistance of the electrode, saline solution was applied to the contact area between the electrode and the sample.

When the surface resistance value was 10 ⁷ Ω/cm or more, it was measured by the compensation electrode method. As a measuring device,
Hewlett-Packard Resistivity Cell/High-
Measured using a Resistance Meter. The sample piece is
A piece measuring 8 cm x 8 cm x 1 mm was used. The half-life of static electricity is measured using the “Static Honestometer” manufactured by Shishido & Co.
Type S-4104''.

Measurement conditions were applied voltage 8000V, temperature 23℃, and humidity.
It was 50%.

Note that the smaller the measured value of the surface resistance and charging half-life, the better the antistatic effect is evaluated.

The sustainability of the antistatic effect is determined by keeping the sample at a temperature of 23°C.
Evaluation was made based on changes in surface resistance and charging half-life after being maintained at 50% humidity for a predetermined period of time.

The number average molecular weight was measured by gel permeation chromatography using tetrahydrofuran as a solvent.

Furthermore, the abbreviations of reagents, etc. used in the following Examples and Comparative Examples are as follows.

AIBN...Azobisisobutyronitrile DMF...Dimethylformamide MEK...Methyl ethyl ketone MMA...Methyl methacrylate THF...Tetrahydrofuran 4VP...4-vinylpyridine Example [Production of high molecular weight monomer] MEK500g, MMA1500g and 52 g of thioglycolic acid were charged into three flasks equipped with a stirring device, and the temperature was raised to 60° C. under a nitrogen stream. When the temperature was raised to 60℃, 10g of AIBN was added as an initiator.
Polymerization started. Three hours after the addition of AIBN, a small amount of hydroquinone was added to stop the polymerization. Further, 500 g of MEK was added to the reaction solution to dilute it, and then poured into a large excess of hexane.
A polymer of MMA with thioglycolic acid bonded to the terminal was obtained. This was purified by reprecipitation twice with MEK/hexane system, and then dried. The yield was 730g. Further, the number average molecular weight was 5.7×10 ³ .

Into a flask with a capacity of 500 ml, 200 g of xylene was charged, followed by 200 g of the above polymer, 9.5 g of glycidyl methacrylate, and 2 g of p-methoxyphenol.
I prepared mg. The above polymer was dissolved while increasing the temperature. When the internal temperature of the flask reached 100°C, N,N-dimethyllaurylamine was added,
The temperature was raised to 130°C and the reaction was continued for 5 hours.

After the reaction was completed, a portion of the reaction solution was collected and acid-base titration was performed to confirm that the -COOH group of thioglycolic acid bonded to the terminal of the polymer had disappeared. Then, after adding MEK and diluting it 3 times,
MMA obtained by adding it to a large excess of hexane
The system high molecular weight monomers were precipitated.

The obtained high molecular weight monomer was further added twice.
It was purified by reprecipitation using MEK/hexane system.

The yield of the MMA-based high molecular weight monomer was 200 g.

[Production of MMA-based high molecular weight monomer-4-vinylpyridine-hydrophilic methacrylate ternary comb copolymer] In a 200 ml flask equipped with a stirring device, 50 g of the above MMA-based high molecular weight monomer, 4 −25 VP
g, as a hydrophilic methacrylate, 25 g of _CH2 =C( _CH3 )CO( _{-OCH2CH2 ) -oOH} (mixture of n=4 and 5) and DMF.
After charging 75g, the temperature was raised to 70°C while stirring. Once the temperature has risen to 70℃, keep it at a constant temperature.
After adding 0.2 g of AIBN and polymerizing for 2 hours,
Polymerization was stopped by adding a small amount of p-methoxyphenol. The reaction solution was diluted 3 times with THF and then poured into a large excess of water to precipitate the comb copolymer. After dehydration and drying, the product was further purified twice by reprecipitation using a THF/water system, and then dried.

The yield was 62g.

As a result of elemental analysis, MMA-based high molecular weight monomer residues
68% by weight, 11% by weight of 4VP residues, and 21% by weight of hydrophilic methacrylate residues.

Using the obtained copolymer, 8cm x 8cm x 1mm
A sample was prepared and treated with hydrochloric acid gas in a desiccator for 24
The surface was pyridinium salted by contacting for a period of time.

The surface resistance of this sample was 1.5×10 ⁵ Ω/cm, and the charging half-life could not be measured because the charging disappeared immediately after the applied voltage was removed.

[Manufacture of composition of ternary comb copolymer and MMA resin] The above ternary comb copolymer was mixed with MMA homopolymer (melt flow index measured at 220°C and 10 kg condition is 3.9) g/10 min) and 4VP residue at a content of 3% by weight (roll kneading at 130°C), and then compression molded at 190°C to a thickness of 1 mm.
A sheet was created. From this sheet, 8cm x 8
A cm sample was cut and exposed to hydrochloric acid gas in a desiccator for 24 hours to form a pyridinium salt. The surface resistance of this sample was 2×10 ⁹ Ω/cm, and the charging half-life was 1 second. This sample was heated to 90℃ and 2mm
After being kept under Hg conditions for 5 hours and after being stored for one month at a temperature of 23° C. and a humidity of 50%, the surface resistance and charging half-life were measured, but no changes were found.

Example 2 [Production of MMA-based high molecular weight monomer-4VP binary comb copolymer] MMA-based high molecular weight monomer 50 produced in Example 1
Polymerization was carried out in the same manner as in Example 1 using 50 g of 4VP.

The obtained rough-shaped copolymer was purified by reprecipitation using a chloroform/hexane system, and then
It was dried under reduced pressure at ℃. Yield of comb copolymer is 69g
It was hot. Hereinafter, this comb-shaped copolymer will be referred to as "comb-shaped copolymer (V)."

Furthermore, the composition according to elemental analysis was 60% by weight of high molecular weight monomer residues and 40% by weight of 4VP residues. The surface resistance measured in the same manner as in Example 1 was 2×10 ⁵
Ω/cm, charging half-life, the charging disappeared immediately after the applied voltage was removed.

[Production of MMA-based high molecular weight monomer-hydrophilic methacrylate binary comb copolymer] MMA-based high molecular weight monomer 25 obtained in Example 1
g and as hydrophilic methacrylate, 25 g of _CH2 =C( _CH3 )CO( _{-OCH2CH2 ) -oOH} (mixture of n=4 and 5), and
Pour 25g of MEK into a 200ml flask with a stirrer,
The temperature was raised to 70°C and maintained at this temperature. AIBN0.05
g was added to start polymerization, and the polymerization was carried out for 2 hours.

After adding a small amount of p-methoxyphenol to stop polymerization, the reaction solution was diluted 3 times with MEK.
This was poured into a large excess of methanol to precipitate a comb copolymer. The comb copolymer was filtered off, washed with methanol, and dried. The yield was 30g. Below, this comb-shaped copolymer is
It is called "comb copolymer (M)."

[Production of composition] 15 g of the comb copolymer (V) and 12 g of the comb copolymer (M) were added to the MMA resin used in Example 1.
It was kneaded with 173g. The 4VP residue content in the composition is
It was 3% by weight. A sheet with a thickness of 1 mm was produced from this composition by press molding, and a sample of 8 cm x 8 cm was cut out.

This sample was treated with hydrogen chloride gas in the same manner as in Example 1, and then the surface resistance and charging half-life were measured.

Surface resistance is 1.5×10 ⁹ Ω/cm, charging half-life is 1
It was less than a second.

This sample was stored for one month under the same conditions as in Example 1, but there was no change in surface resistance or charging half-life.

Example 3 Comb copolymer (V) produced in Example 2,
ABS resin (Mitsubishi Monsanto Chemical Co., Ltd. TFX −
410CB) so that the 4VP residue content was 2% by weight, a sheet with a thickness of 1 mm was prepared using the composition, and quaternized in the same manner as in Example 1. After that, the surface resistance and charging half-life were measured.

As a result, the surface resistance was 1×10 ¹⁰ Ω/cm, and the charging half-life was 2 seconds. Even after one month had passed, there was no change in the above measured values.

Comparative Example 1 A SO ₃ Na comb copolymer-MMA resin composition was produced according to the description in Example 6 of JP-A-59-230057. The surface resistance and charging half-life of the above composition were measured according to the method described in this specification, and the surface resistance was 2×10 ¹² Ω/cm, and the charging half-life was 3.5 seconds.

In the same manner as in Example 1, the surface resistance after one month was 2×10 ¹³ Ω/cm, and the charging half-life was 6 seconds.

That is, the durability of the antistatic effect is lower than that of the comb copolymers according to the present invention (Examples 1 to 3).

Comparative Example 2 [Manufacture of 4VP-MMA random copolymer] 50 g of 4VP, 50 g of MMA, and 50 g of DMF were weighed into a 200 ml flask equipped with a stirrer, and the temperature was raised to 70°C. Next, 0.38 g of AIBN was added to initiate polymerization. After 3 hours, it was stopped by adding a trace amount of hydroquinone.

The polymer was diluted to 3 times its volume with methanol and poured into a large amount of water to recover the polymer, and then purified by reprecipitation using THF/hexane. The yield of dry polymer was approximately 50 g, and the 4VP residue content was 56.3% by weight.

[Production of Composition] The random copolymer and MMA resin were kneaded so that the 4VP residue content was 3% by weight. Using the obtained composition, a sheet with a thickness of 1 mm was prepared and quaternized in the same manner as in Example 1. The surface resistance was 1×10 ¹² Ω/cm, and the charging half-life was 13 seconds.

Compared to the case of using a comb-shaped copolymer containing 4VP residues (Examples 1 to 3), the surface resistance and
Both charging half-lives deteriorated.

Claims (1)

[Scope of Claims] 1. Consists of a polymer portion consisting of vinyl monomer residues having a number average molecular weight of 1×10 ³ to 2×10 ⁴ ,
Moreover, the polymer portion is composed of 20 to 80% by weight of high molecular weight monomer residues having a polymerizable vinyl group at one end, vinylpyridine monomer residues, and vinylpyridinium monomer residues. The use of a vinylpyridine-based comb copolymer consisting of 80 to 20% by weight of at least one monomer residue selected from the group consisting of 0 to 60% by weight of a hydrophilic monomer residue Characteristic antistatic agent. 2. The antistatic agent according to claim 1, wherein the vinyl monomer residue is a methyl methacrylate residue. 3. The antistatic agent according to claim 1 or 2, which contains 10 to 30% by weight of hydrophilic monomer residues.