JPH11256144A - Antistatic agent and antistatic filler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antistatic agent that has excellent antistatic performance and excellent durability by containing a polymer bearing a specific structural unit and a lithium salt. SOLUTION: This antistatic agent comprises (A) a polymer that has a recurring unit of formula I ((n) is 10 or more; R1 is H, methyl; R2 is an alkyl, an alkyl-substituted phenyl) such as a methacrylate prepared by esterifying the terminal OH groups of a poly ((oligo)-ethylene glycol) having polymerized ethylene oxide of 10 or more polymerization degree with (meth)acryloyl groups and further another recurring unit of formula II (R3 is H, methyl; Q is a divalent linking group; A is a sulfonic acid group, phosphoric acid group, carboxylic acid group or the like) and (B) a lithium salt. In a preferred embodiment, the weight ratio of the component A to the component B is 100/(5-100), particularly 100/(10-50).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antistatic agent which can be used for kneading or coating a plastic, and an antistatic filler whose filler surface is coated with the antistatic agent.

[0002]

2. Description of the Related Art Conventionally, techniques for preventing static electricity on an insulator such as plastic or rubber include a method of applying a conductive substance to the surface of an insulator to impart conductivity to the surface, and a method of applying a plastic to rubber. Knead conductive material into insulator such as rubber,
A method of lowering the volume resistance value or the surface electric resistance value to impart antistatic performance and the like have been performed. Conductive substances used for such purposes include low molecular weight antistatic agents such as surfactants, and high molecular weight polymer type antistatic agents,
Alternatively, examples thereof include metal fine particles, metal oxide fine particles such as titanium oxide, zinc oxide, and tin oxide, conductive carbon black, and various other conductive fillers.

A coating type antistatic agent for coating on the surface of an insulator is mainly used for a sheet material such as a film, and is often required to have transparency. In addition, ultrafine particles of tin oxide doped with antimony and the like are often used, but have problems in adhesion to the sheet surface, durability of the antistatic layer, weather resistance, and the like.

In a method in which a conductive substance is directly kneaded into an insulating plastic, rubber, or the like, an antistatic property may be imparted by adding a relatively small amount of a low-molecular type antistatic agent.
There have been problems such as contamination by the antistatic agent deposited on the surface, and the effect thereof is easily lost by washing with water. The polymer type antistatic agent has a relatively small problem of persistence of antistatic performance after kneading and surface contamination, but a problem that it is difficult to disperse uniformly in plastic, rubber, etc. at the time of kneading, Since a large amount (10% by weight or more) of kneading is required, there is a problem that the properties of the plastic, rubber and the like after kneading are greatly affected by the antistatic agent.

In a method of kneading conductive fillers such as conductive carbon black, metal fine particles, and metal oxide fine particles into plastics, rubber, etc., in order to maintain conductivity, the conductive fillers come into contact with each other in a matrix. In many cases, at least about 30% by volume of the conductive filler is required. At such an introduction rate, the influence of the filler on the physical properties (mechanical and optical properties) of plastic, rubber, etc. was very important.

[0006] Further, when the above filler is kneaded into a plastic, rubber or the like and used, the dispersibility of the filler is very important, and the filler which has been conventionally used as a filler for plastic, rubber or the like is used. In order to improve compatibility or dispersibility with a matrix, a filler whose surface is coated with a hydrophobic substance such as stearic acid is used. However, the filler coated with such a hydrophobic substance loses its own surface conductivity, so that the antistatic performance of plastics, rubber, and the like filled with these fillers may be insufficient. Further, for example, as disclosed in JP-A-56-136849 and JP-A-59-138267,
Attempts have been made to previously treat the filler with an antistatic agent. However, in the case of easily chargeable plastics such as polyethylene and polypropylene, even if an antistatic agent is added, the surface electric resistance and the volume resistance do not decrease, and a sufficient antistatic effect is often not obtained. Even if the surface electric resistance or the like is lowered and the desired antistatic effect is obtained, the migration of the antistatic agent to the surface of the object to be treated is large,
There is a problem that the effect is temporary and has no durability.

Further, as fillers for plastics, rubbers, etc., light calcium carbonate, heavy calcium carbonate, talc, sericite, calcium sulfate, montmorillonite, zeolite, calcium sulfite, aluminum hydroxide, aluminum oxide, zinc oxide, One or a mixture of two or more of various inorganic substances such as titanium oxide, barium sulfate, and kaolin, particularly fillers such as heavy calcium carbonate and titanium oxide are preferably used. When the above filler is kneaded into plastic, rubber, or the like, the kneading dispersibility is usually improved by treating the surface of the filler by some method. None of them provided antistatic properties. For example, a filler whose surface is coated with a low molecular weight antistatic agent such as a surfactant can achieve both the dispersibility of the filler and the antistatic performance after kneading, but the surfactant is applied to the surface. In many cases, a durable antistatic process cannot be performed because of bleed-out and contamination of the surface, or loss of antistatic performance after washing with water. In addition, those in which the filler surface is coated with a polymer type antistatic agent, as shown in Comparative Examples described in Examples described later, the kneading property is extremely deteriorated, and uniform kneading is not performed. There was a problem.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an antistatic agent capable of imparting an antistatic property to a plastic, rubber or the like by applying or kneading a small amount thereof. By coating with an inhibitor, the kneading dispersibility in plastics, rubber, etc. is improved, and the antistatic layer is formed on the filler surface, so that the kneaded plastic,
It is intended to impart good antistatic performance to rubber and the like.

[0009]

Means for Solving the Problems The present invention firstly provides an antistatic agent comprising a polymer having a repeating unit represented by the formula (I) and a lithium salt.

[0010]

Embedded image

[0011] (wherein, n represents an integer of 10 or more, R ₁
Represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an alkyl-substituted phenyl group.

Secondly, the present invention is characterized in that it comprises a polymer having a repeating unit represented by the formula (II) in addition to the repeating unit represented by the formula (I), and a lithium salt. Agent. This is preferable because the resistance value of the antistatic agent can be further reduced.

[0013]

Embedded image

(Wherein, R ₃ represents a hydrogen atom or a methyl group, Q represents a divalent linking group, A represents a sulfonic acid group, a phosphoric acid group, a carboxylic acid group or a neutralized acid group thereof. Represents a group)

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As a preferable example of a monomer giving a repeating unit represented by the formula (I), a poly (ethylene-oxy group having a degree of polymerization of 10 or more having an alkyl group or an alkyl-substituted phenyl group at one terminal, Methacrylates or acrylates in which the terminal group of (oligo) ethylene glycol is esterified with a methacryloyl group or an acryloyl group are particularly preferably used. As the alkyl group for R ₂ , a linear or branched alkyl group having 1 to 25 carbon atoms is preferable because it exhibits good miscibility with plastics, rubber, and the like. The preferable range of n is about 12 to 50, and preferable properties can be exhibited.

The proportion of the repeating unit represented by the above formula (I) in the polymer is preferably in the range of 10% by weight to 100% by weight, more preferably in the range of 50% by weight to 100% by weight.

In the formula (II), the divalent linking group represented by Q is not particularly limited, and may be any group as long as it is a group linking A, which is an acid group, to a radical polymerizable double bond. Linking groups are included in this. Examples of preferred monomers of the formula (II) include, as monomers having a sulfonic acid group, styrenesulfonic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, acrylamidomethylpropanesulfonic acid and salts thereof; The monomers having the following are acid phosphooxyethyl methacrylate, acid phosphooxypropyl methacrylate, and 3
-Chloro-2-acid phosphooxypropyl methacrylate, acid phosphooxy polyethylene glycol monomethacrylate, acid phosphooxy polypropylene glycol monomethacrylate and salts thereof;
Further, examples of the monomer having a carboxylic acid group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride and salts thereof.

In the polymer, those in which the proportion of the repeating unit represented by the formula (II) accounts for 50% by weight or less are preferable because of their good dispersibility when kneaded into plastic, rubber or the like.

In addition to the monomers according to the present invention, styrene derivatives such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene and 4-methoxystyrene; methyl methacrylate , Ethyl methacrylate,
Alkyl methacrylates such as butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, aryl methacrylates or alkyl aryl esters such as phenyl methacrylate and benzyl methacrylate; methacrylic acid Amino group-containing methacrylates such as 2-dimethylaminoethyl and 2-diethylaminoethyl methacrylate; or similar examples of the corresponding methacrylates as acrylates; or p-vinylbenzyltrimethylammonium chloride Monomers having a quaternary ammonium base; Amino group-containing monomers such as allylamine and diallylamine; or 4-vinylpyridine, 2-vinylpi Jin, N- vinylimidazole,
Monomers having a nitrogen-containing heterocycle such as N-vinylcarbazole; or acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, N-isopropylacrylamide, diacetoneacrylamide, N
Acrylamide or methacrylamide derivatives such as methylol acrylamide and N-methoxyethyl acrylamide; and vinyl esters such as acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate and vinyl benzoate. And methyl vinyl ether,
Vinyl ethers such as butyl vinyl ether;
Various monomers such as N-vinylpyrrolidone, acryloylmorpholine, tetrahydrofurfuryl methacrylate, vinyl chloride, vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, and glycidyl methacrylate can be used as a copolymerization monomer.

When such other copolymerizable monomer is further introduced into the polymer, if the other monomer is introduced in a proportion exceeding 50% by weight in the polymer, the antistatic performance is impaired. In some cases, this is not preferable.

Preferred lithium salts to be added to the polymer having a repeating unit of the above formula (I) or the formulas (I) and (II) include lithium chloride, lithium sulfate, lithium acetate, lithium phosphate, lithium carbonate, Examples thereof include lithium perchlorate and lithium trifluoromethanesulfonate. The lithium salt is preferably added to the polymer in a form dissolved in water or another suitable solvent, and several oxyethylene units in the repeating unit represented by the formula (I) in the polymer and an ionic complex are added. Which is a factor for imparting good conductivity.

A feature of the present invention is that a polymer having an ionic complex exhibits extremely good conductivity because such a repeating unit forming an ionic complex is present in a side chain of the polymer. There is also a feature. Normally, when an ionic complex is formed with a lithium salt or the like, plasticity, kneading property to rubber or the like is reduced, and uniform kneading may be difficult. At the same time as the kneading is carried out without hindrance, after kneading, the antistatic agent of the present invention having formed the ionic complex is transferred to the vicinity of the surface of plastic, rubber, etc., and even if a small amount is added, the surface resistance is increased Effectively lowers the
It is very effective as a kneading type antistatic agent.

The antistatic agent of the present invention containing a polymer having a repeating unit represented by the formula (I) or the formulas (I) and (II) and an appropriate lithium salt is used for both application and kneading. Can exhibit good antistatic performance, but the mixing ratio of the polymer and the lithium salt is
The lithium salt is preferably used in an amount of 5 to 100 parts by weight, particularly preferably 10 to 50 parts by weight, per 100 parts by weight.
The molecular weight of the polymer is preferably in the range of several thousand or more to several million or less, and within this range, the stability after forming a complex with the lithium salt is high. For example, the polymer is kneaded into a plastic or rubber for kneading. It is particularly effective because it shows a very preferable property that the surface resistance does not change even if the water washing treatment is repeated when used.

In addition to the kneading method, the surface coating method can be preferably used. However, when the antistatic performance is required to be continuous, the kneading use improves the sustainability. When used as a kneading type, excellent antistatic performance can be exhibited with an addition amount of about several percent based on the total weight of plastic or rubber, but when used as a coating type when applied to sheets. The effect is effective when the thickness of the surface coat layer is about 0.1 μm.

The antistatic agent of the present invention can also be used as a surface treatment agent for various fillers for producing an antistatic filler kneaded into plastic, rubber, or the like.

The antistatic filler of the present invention has the formula (I)
Or a polymer having a repeating unit represented by the formula (I) and the formula (II), or a filler coated with an antistatic agent containing the polymer and a lithium salt, wherein the coated filler is a plastic, It is possible to improve the kneading dispersibility in rubber and the like, and to remarkably enhance the antistatic performance of plastic, rubber and the like after kneading the filler. In plastics and rubbers filled with fillers, in order to maintain the uniformity of the fillers, it is preferable to use a finely pulverized filler having a particle size of several tens to several microns, and a size of one micron or less. What is finely ground is more preferably used. In order to pulverize to such a size, use a pulverizer such as a sand mill, ball mill, attritor, etc.
What is wet-ground is usually used. As a method of surface coating the filler with an antistatic agent, for example, in the wet grinding step of the filler, a liquid in which the polymer is dispersed in a slurry in advance is added to the filler, and the filler is dried after the wet grinding. This makes it possible to coat the surface with an antistatic agent. Or
It is also preferable to add the polymer to a wet-milled or dispersed filler liquid and then dry it to coat the surface. Alternatively, it is also preferable to apply a surface coating to the dried filler after the pulverization by a method such as spray coating. In addition, in order to add the lithium salt together, either a method of adding a lithium salt to the polymer in advance or a method of adding a lithium salt to a filler coated with the polymer may be used. The ratio of the polymer as the antistatic agent to the filler is preferably in the range of 0.5 to 10 parts by weight of the antistatic agent with respect to 100 parts by weight of the filler. It is preferable that the amount of the plastic or rubber is 100 to 300 parts by weight based on 100 parts by weight of the filler.

The antistatic filler of the present invention, the surface of which is coated with the polymer or the polymer and a lithium salt by the above method, has good dispersibility in various plastics and rubbers.
There is no particular problem in kneading, and the resistance value can be further reduced because the lithium salt is firmly fixed in the polymer, and the resistance value can be reduced even if the plastic or rubber after kneading is washed with water. No major change is observed.

[0028]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Parts in Examples are parts by weight.

Synthesis Examples 1 and 2 Using methacryloyl chloride in an equimolar amount to polyethylene glycol monostearate (degree of polymerization of ethylene oxide n = 25, Tokyo Kasei), using THF as a solvent,
A methacrylic acid ester monomer (M-1) was synthesized in the presence of pyridine at 0 ° C. according to a conventional method. In exactly the same way, a monomer (M-2) was synthesized from polyethylene glycol-4-nonylphenyl monoether (n = 15) and methacryloyl chloride. Using the monomers M-1 and M-2 obtained as described above, corresponding polymers P-1 and P-2 were synthesized as follows. Take 20 parts of sodium styrenesulfonate and 80 parts of monomer M-1 or M-2, and add 45 parts of distilled water
0 parts and 50 parts of ethanol, and heated and stirred at 60 ° C. in a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux condenser tube, and V-50 (2 , 2'-azobis (2-amidinopropane) dihydrochloride, manufactured by Wako Pure Chemical Industries, Ltd.) to initiate polymerization. Polymerization was performed at this temperature for 5 hours to obtain polymer solutions P-1 and P-2 having a weight average molecular weight of about 300,000.

Synthesis Examples 3 to 6 and Comparative Synthesis Examples 1 to 3 The compositions shown in Table 1 were polymerized in the same manner as in Synthesis Examples 1 and 2 to obtain respective polymer solutions.

[0031]

[Table 1]

MAA = methacrylic acid, SSS = sodium p-styrenesulfonate, QBm = p-vinylbenzyltrimethylammonium chloride, NK-230G = methoxypolyethylene glycol # 1000
Methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester M-230G, n = 23), NK-20G = methoxydiethylene glycol methacrylate (〃, n = 2), NK-60G = methoxypolyethylene glycol # 230 methacrylate (〃, n) = 4), NF-N177E (alkylphenyl polyethylene glycol methacrylate, ethylene oxide polymerization degree n = 16-1)
7. New Frontea N-177, manufactured by Daiichi Kogyo Seiyaku
E), PM-M = acid phosphooxyethyl methacrylate (Phosmer M manufactured by Unichemical Co., Ltd.), and PM-PE = acid phosphooxy polyethylene glycol methacrylate (Δ, phosmer PE).

Example Using the polymer solutions obtained in the above synthesis examples and comparative synthesis examples, a kneading test was carried out on a plastic (here, low-density polyethylene was used). In Table 2, Samples 1 and 2 and Comparative Sample 1 were prepared by mixing a lithium salt with a polymer solution at a solid content weight ratio shown in the table and evaporating to dryness to obtain a polymer mixture. Other samples were obtained by wet grinding heavy calcium carbonate or titanium oxide.
A polymer solution was added to a 0% by weight aqueous dispersion together with a lithium salt at a solid content ratio shown in the table (however, the lithium salt was not added in Sample 3) and evaporated to dryness to prepare a filler. . A kneading test of the polymer mixture or filler obtained as described above into low-density polyethylene at a solid content ratio shown in the table was carried out using a Labo Plastomill manufactured by Toyo Seiki. The stirring speed at the time of addition to the polyethylene was 10 rpm, and the melting temperature was 150 ° C. After the addition, the stirring speed was further increased to 60 rpm, and the mixture was further mixed at 150 ° C. for 5 minutes. The sample after kneading was formed into a film sample under the conditions of a pressing pressure of 30 kg / cm ² and a temperature of 150 ° C. using a hot press machine. Table 3 summarizes the evaluations of the obtained film samples.

[0034]

[Table 2]

[0035]

[Table 3]

In Table 3, the resistance value of the fresh sample was measured by humidifying the sample in a 20 ° C., 30% temperature and humidity atmosphere for 24 hours, and then measuring the high-resistivity meter Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd. Measured using After the water washing in the measurement of the resistance value, the sample was washed with hot water of 40 ° C. for 1 hour, dried and then conditioned for 24 hours in a temperature and humidity atmosphere of 20 ° C. and 30%. Similarly, the resistance value was measured.
Evaluation of the dispersibility is visually determined the state of the film sample,
When the film was a homogeneous film, it was evaluated as ○, and when the presence of aggregates or the like was clearly recognized, it was evaluated as ×.

[0037]

By kneading the antistatic agent and the filler containing the same according to the present invention into plastics, rubber, etc., good antistatic performance with excellent durability can be imparted.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C08K 9/04 C08K 9/04 C08L 33/14 C08L 33/14 (72) Inventor Akira Nakayama Akira Marunouchi 3-chome, 4-chome, Chiyoda-ku, Tokyo No. 2 Mitsubishi Paper Mills Co., Ltd. (72) Inventor Yumiko Takase 2-8-6 Nishi-Shimbashi, Minato-ku, Tokyo Sumitomo Realty & Development, Hibiya Building 12th Floor, FIMATECH Co., Ltd. (72) Inventor Ryoji Ito, Nishi-Shimbashi, Minato-ku, Tokyo 2-8-6 Sumitomo Realty & Development, Hibiya Building 12F

Claims (4)

[Claims] 1. An antistatic agent comprising a polymer having a repeating unit represented by the formula (I) and a lithium salt. Embedded image (In the formula, n represents an integer of 10 or more, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an alkyl-substituted phenyl group.) 2. An antistatic agent comprising a polymer having both the repeating unit represented by the formula (I) and the repeating unit represented by the following formula (II), and a lithium salt. Embedded image (Wherein, R ₃ represents a hydrogen atom or a methyl group, and Q represents 2
Represents a valent linking group, and A represents a sulfonic acid group, a phosphoric acid group, a carboxylic acid group or a group in which these acid groups are neutralized) 3. An antistatic filler having a filler surface coated with the polymer according to claim 1. 4. An antistatic filler, wherein the filler surface is coated with the polymer according to claim 1 and a lithium salt.