JP2007145893A - Antistatic agent for pressure-sensitive adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antistatic agent for a pressure-sensitive adhesive forming a pressure-sensitive adhesive layer having good antistatic properties and hardly sticking foreign materials such as dirt onto the surface by compounding the antistatic agent in the pressure-sensitive adhesive. <P>SOLUTION: The antistatic agent for the pressure-sensitive adhesive is composed of a compound as follows. A diol compound to which an alkali metal atom is added is bonded to a diisocyanate compound with a urethane bond (-NHCO-). The compound has an isocyanate group (-NCO) at the end. The diol compound is preferably a condensate of a 2-100C straight-chain or branched alkylene glycol. The alkali metal atom is preferably a lithium atom. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an antistatic imparting agent for pressure-sensitive adhesives, and more particularly to an antistatic agent for pressure-sensitive adhesives that provides a stable antistatic effect and is less likely to bleed out from the surface of the pressure-sensitive adhesive layer.

  Conventionally, as a surface protective film (sheet) imparted with antistatic properties, (1) an antistatic agent layer containing a quaternary ammonium salt is formed on one or both sides of a sheet-like substrate, and an adhesive layer is formed thereon. (For example, refer to Patent Document 1), and (2) a low molecular surfactant added to an adhesive layer provided on one or both sides of a sheet-like base material.

However, in (1), since the antistatic agent layer is thin and between the substrate and the adhesive layer and exhibits an antistatic effect via the adhesive layer, there is a problem that the antistatic effect on the surface of the adhesive layer is inferior. . In (2), since a low molecular surfactant is present on the surface of the pressure-sensitive adhesive layer, the surface of the pressure-sensitive adhesive layer has a low resistance, and a good antistatic effect can be obtained initially. There is a problem that bleed out from the surface of the adhesive layer and foreign matter such as dust adheres to the surface of the adhesive layer or the antistatic effect is lowered.
JP 2000-273417 A

  In view of the above circumstances, the problem to be solved by the present invention is to form an adhesive layer that has an excellent antistatic effect by mixing with an adhesive, and that the antistatic effect is unlikely to decrease. An antistatic agent for pressure-sensitive adhesives is provided.

  As a result of diligent research to achieve the above object, the inventors of the present invention incorporated a modified urethane polymer obtained by adding a diisocyanate to a diol to which an alkali metal atom was added and performing a urethanization reaction into the adhesive. It has been found that an adhesive layer having a sufficiently low surface resistance can be formed, and that the low surface electric resistance is maintained even when the surface is exposed to heat or moisture, and the present invention has been completed.

That is, the present invention
(1) An antistatic agent for pressure-sensitive adhesives comprising a polymer compound in which a diol compound to which an alkali metal atom is added and a diisocyanate compound are bonded by a urethane bond (-NHCO-) and having an isocyanate group (-NCO),
(2) The antistatic agent according to (1) above, wherein the diol compound is a condensate of a linear or branched alkylene glycol having 2 to 100 carbon atoms,
(3) The antistatic agent according to (1) or (2) above, wherein the weight average molecular weight is 500 to 100,000.
(4) The antistatic agent according to any one of the above (1) to (3), wherein the alkali metal atom is a lithium atom, and (5) the above (1) to ( It relates to the antistatic agent as described in any one of 4).

  According to the antistatic agent of the present invention, since it exhibits high conductivity and has an isocyanate group at the terminal, the isocyanate group reacts with the hydroxyl group of the adhesive to be integrated with the adhesive (chemically). To join). Therefore, when the adhesive layer is formed with an adhesive containing the antistatic agent of the present invention, it is possible to suppress problems due to bleedout of the antistatic agent (foreign substances such as dust attached, deterioration of antistatic performance, etc.), which is excellent. An adhesive layer having both adhesiveness and antistatic properties can be formed.

Hereinafter, the present invention will be described in more detail.
The antistatic agent for pressure-sensitive adhesives of the present invention comprises a polymer compound in which a diol compound to which an alkali metal atom is added and a diisocyanate compound are bonded by a urethane bond (-NHCO-) and has an isocyanate group (-NCO). Become.

  As the diol compound referred to in the present invention, a linear or branched alkylene glycol having 2 to 100 carbon atoms (for example, ethylene glycol, propylene glycol, tetramethylene glycol, 1,3-butanediol, 1,4-butanediol, Neopentyl glycol, 1,6-hexanediol, 1,9-nonanediol, etc.), bisphenol A, etc. or condensates thereof (for example, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol) Polymer, ethylene oxide ring-opening adduct of bisphenol A, propylene oxide ring-opening adduct of bisphenol A, etc., and polyester diol (for example, polyadipate diol, A carbonate diol, a polycaprolactone diol, etc.). Among them, a condensate of a linear or branched alkylene glycol having 2 to 100 carbon atoms is preferable, and polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol are particularly preferable. It is a copolymer.

  The said diol compound may be 1 type, or 2 or more types may be used together. The molecular weight is preferably 50 to 10,000, more preferably 100 to 5,000, and particularly preferably 500 to 2,000.

  Examples of the alkali metal atom in the present invention include lithium, sodium, potassium, rubidium, cesium and the like, preferably lithium, sodium, potassium, more preferably lithium.

  Examples of the diisocyanate compound used in the present invention include hexamethylene diisocyanate, isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate, tolidine diisocyanate, xylylene diisocyanate, bis (isocyanate methyl) cyclohexane, Examples include 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate are preferable.

  The antistatic agent of the present invention can be obtained by adding an alkali metal atom to a diol compound and then adding a diisocyanate compound to the diol compound to which the alkali metal atom has been added to carry out a urethanization reaction.

The addition reaction of an alkali metal atom to a diol compound is, for example, a perchlorate represented by MClO ₄ (M is an alkali metal atom) in the diol compound, toluene, benzene, acetate ester, methyl ethyl ketone, acetone, etc. It can carry out by making it react at normal temperature or a heating in a solvent of no or no solvent. At this time, the amount of perchlorate (MClO ₄ ) used is preferably approximately equimolar to the diol compound (that is, about 1 ± 0.01 to 0.5 mol relative to 1 mol of the diol compound). Moreover, 30-100 degreeC is preferable for the temperature at the time of heating. The reaction time is usually about 1 hour to 20 hours. After the reaction, the target product is obtained by distilling off the solvent.

  Moreover, the urethanation reaction between a diol compound to which an alkali metal atom is added and a diisocyanate compound is usually carried out in an organic solvent such as toluene or acetate ester or without solvent at room temperature or under heating (about 30 to 100 ° C.). Is called. The amount of the diisocyanate compound used is preferably about 1 + 0.01 to 0.5 mol and more preferably about 1 + 0.05 to 0.2 mol with respect to 1 mol of the diol compound. The reaction time is usually about 1 hour to 10 hours. Moreover, as a catalyst used for a urethanation reaction, what is necessary is just to use the general thing used as a catalyst for urethanation reaction, However, Dibutyltin laurate, a triethylamine, a triethanolamine etc. are preferable among these.

  The antistatic agent of the present invention (that is, a polymer compound in which a diol compound to which an alkali metal atom is added and a diisocyanate compound are bonded by a urethane bond (-NHCO-) and has an isocyanate group (-NCO)), From the product after the urethanization reaction, the solvent is distilled off, washed, etc., and collected as a solid and used for blending into an adhesive, or the product after the urethane reaction is further diluted with a solvent. , It may be mixed with an adhesive solution to form a coating solution for forming an adhesive layer. In that case, the solution obtained by diluting the product after the urethane reaction with a solvent is preferably prepared to a solid content concentration of about 10 to 90% by weight.

  In the antistatic agent of the present invention, the content of isocyanate groups (—NCO) is preferably 0.05 to 50% by weight, more preferably 1 to 10% by weight. If the isocyanate group (-NCO) content is less than 0.05% by weight, sufficient reactivity with the pressure-sensitive adhesive is difficult to obtain, and if it exceeds 50% by weight, this is blended into the pressure-sensitive adhesive. Since the (liquid) pot life of an adhesive composition becomes short, it is not preferable.

  The antistatic agent of the present invention has a weight average molecular weight of preferably 500 to 100,000, more preferably 1,000 to 5,000, and particularly preferably 1,000 to 2,000. When the weight average molecular weight exceeds 100,000, the isocyanate equivalent becomes too small, so that the reactivity becomes low and the viscosity tends to increase remarkably. Since the equivalent becomes too large, the reactivity becomes too high, and the (liquid) pot life of the pressure-sensitive adhesive composition blended with the pressure-sensitive adhesive is shortened, which is not preferable.

  The antistatic agent of the present invention preferably has an alkali metal atom content of 0.01 to 20% by weight, more preferably 1 to 10% by weight. If it is less than 0.01% by weight, a sufficient antistatic effect is hardly exhibited. If it exceeds 20% by weight, a perchlorate or the like is added to the diol compound so as to contain such a large amount of alkali metal atoms. In this case, the exotherm becomes intense and the reaction cannot be controlled.

  In the antistatic agent of the present invention, a pigment, an organic filler, an inorganic filler, a lubricant, an antiblocking agent and the like can be blended as long as the object of the present invention is not impaired.

  When the antistatic agent of the present invention is blended with a pressure-sensitive adhesive having a hydroxyl group, the terminal isocyanate group (—NCO) reacts with the hydroxyl group (—OH) of the pressure-sensitive adhesive to chemically form the polymer chain of the pressure-sensitive adhesive. Combine and integrate with adhesive. Examples of the pressure-sensitive adhesive having a hydroxyl group include an acrylic pressure-sensitive adhesive, a phenol resin-based adhesive, and a rubber-based pressure-sensitive adhesive, and an acrylic pressure-sensitive adhesive is preferable. When the antistatic agent of this invention is mix | blended with an acrylic adhesive, the adhesion layer which has especially favorable antistatic property can be formed.

  As used herein, the acrylic pressure-sensitive adhesive is obtained by copolymerizing a vinyl monomer having a hydroxyl group (hereinafter referred to as “hydroxyl group-containing vinyl monomer”) with a main monomer composed of (meth) acrylic acid alkyl ester. It is a polymer. Specific examples of the (meth) acrylic acid alkyl ester as the main component (main monomer) include primary to tertiary alcohols having 2 to 18 (preferably 4 to 12) carbon atoms in the alkyl group and acrylic acid or Mention may be made of esters with methacrylic acid, and these may be used alone or in combination. The hydroxyl group-containing vinyl monomer has at least one addition-polymerizable unsaturated double bond (vinyl group) in the molecule, and has a hydroxyl group-containing functional group such as a carboxyl group or a hydroxyl group in the side chain. The functional monomer possessed by Examples of the functional monomer in which the hydroxyl group-containing functional group is a carboxyl group include (meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, etc., and the functional monomer having a hydroxyl group-containing functional group is a hydroxyl group. Examples of the monomer include (meth) acrylic acid hydroxyethyl ester, (meth) acrylic acid hydroxypropyl ester, and the like. The functional monomer is also used alone or in combination of two or more. In addition to the above functional monomers, for example, (meth) acrylonitrile, vinyl acetate, vinyl propionate, N-vinyl-2-pyrrolidone, N-vinylacetamide, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine , Vinyl piperazine, vinyl pyrrole, vinyl imidazole, vinyl caprolactam, vinyl oxazole, vinyl morpholine and the like may be further copolymerized.

  In the present invention, the copolymer composition ((meth) acrylic acid alkyl ester / hydroxyl group-containing vinyl monomer) in the acrylic pressure-sensitive adhesive (copolymer) ranges from 50 to 98% by weight / 2 to 50% by weight. In general, it has a copolymer composition, but preferably has a hydroxyl value in the range of 5 to 100 mgKOH / g, and a hydroxyl value in the range of 15 to 30 mgKOH / g. Is more preferable.

  The amount of the antistatic agent used in the present invention is preferably about 0.1 to 50 parts by weight, more preferably about 1 to 10 parts by weight per 100 parts by weight of the pressure-sensitive adhesive (solid content). Further, the ratio (NCO / OH) of the isocyanate group (—NCO) in the antistatic agent to the hydroxyl group (—OH) in the pressure-sensitive adhesive is 1/10 within the range of the weight ratio. -50 (molar ratio) is preferable, and 1 / 20-50 (molar ratio) is more preferable.

  The pressure-sensitive adhesive containing the antistatic agent of the present invention can be used as a pressure-sensitive adhesive layer for various articles in which a pressure-sensitive adhesive layer is formed on at least a part of the surface of the pressure-sensitive adhesive. In particular, the pressure-sensitive adhesive sheet (film) obtained by applying to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (film) is suitable as a surface protective sheet (film). That is, during use, dust and the like can be prevented from adhering to the surface of the adhesive, and since the adhesive layer can be prevented from being charged, static electricity generated when the surface protective sheet (film) is peeled off can be prevented. , And the problem of getting around the surroundings does not occur. Therefore, the surface of the protection target object can be protected without impairing the beauty of the protection target object.

  When producing a surface protective sheet (film) having an adhesive layer formed of an adhesive composition in which the antistatic agent of the present invention is mixed with an adhesive, the support is made of a highly transparent synthetic resin sheet (film). Are used, and examples thereof include sheets of polyethylene, polypropylene, polyimide, polycarbonate, polyvinyl chloride, polyester, polyurethane, and the like.

  The pressure-sensitive adhesive layer is formed by preparing a pressure-sensitive adhesive solution containing an antistatic agent together with a pressure-sensitive adhesive, and applying the pressure-sensitive adhesive solution to a general coating apparatus such as a roll coater method, a reverse coater method, or a doctor blade method. It is used by coating on a support and heating the coating film at a temperature of 30 to 120 ° C. for about 1 to 5 minutes. By the heating, the solvent is volatilized (evaporated), and the isocyanate group (—NCO) in the antistatic agent reacts with the hydroxyl group (—OH) in the adhesive, so that the adhesive and the antistatic agent are integrated. Turn into. When the heating temperature is less than 30 ° C., the solvent tends to remain, and when the heating temperature exceeds 120 ° C., the surface of the coating film is colored and the support is likely to deteriorate, which is not preferable.

  About 1-100 micrometers is preferable and, as for the thickness (thickness after drying) of the adhesion layer, about 1-20 micrometers is more preferable. When the thickness of the adhesive layer is less than 1 μm, it is difficult to obtain a sufficient adhesive force, and when it exceeds 100 μm, the solvent may remain in the layer, which is not preferable.

  In the pressure-sensitive adhesive sheet (film), a release sheet (liner) can be provided on the pressure-sensitive adhesive surface. As the release sheet (liner), synthetic resin, paper, all kinds of cloth, metal foil, and the like can be used. Specific examples include polyethylene, polypropylene, polyimide, polycarbonate, polyvinyl chloride, polyester, polyurethane, cellophane, impregnated paper, coated paper, fine paper, craft paper, cloth, acetate cloth, non-woven cloth, glass cloth, and metal foil. However, it is not limited to these. Various release treatment agents (silicone-type release treatment agent, fluorine-type release treatment agent, long-chain alkyl release treatment agent, etc.) can also be applied to the surface of the release sheet (liner).

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

  The viscosity, hydroxyl value, weight average molecular weight and alkali metal atom content in the present specification were measured by the following methods.

1. Viscosity Viscosity measurement was performed at 25 ° C. using a BL type viscometer.

2. Hydroxyl value A sample of 2 to 5 g was precisely weighed, saponified with pyridine-acetic anhydride, and titrated with 0.1 N KOH to determine the hydroxyl value.

3. Weight average molecular weight Measured by gel permeation chromatography (GPC) (polystyrene conversion).
Measuring device: TSK Multipore H _VL -M
Solvent: Tetrahydrofuran

4). Alkali metal atom content Measured with an atomic absorption spectrophotometer AA-6800 manufactured by Shimadzu Corporation.

[Production of alkali metal atom addition diol compound]

Production Example 1
Polyethylene glycol (100 g) having a molecular weight of 1000 and lithium perchlorate (10 g) were reacted in methyl ethyl ketone (500 ml) at 60-80 ° C. for 18-20 hours. After confirming the completion of the reaction with FT-IR (620 cm ⁻¹ ), methyl ethyl ketone was removed at 50 ° C. under reduced pressure (10 mmHg). The product had a viscosity of 2,500 mPa · s / 25 ° C. and a hydroxyl value of 78 mgKOH / g.

Production Example 2
The same treatment as in Production Example 1 was performed except that polypropylene glycol having a molecular weight of 1000 was used instead of polyethylene glycol having a molecular weight of 1000. The product had a viscosity of 3,600 mPa · s / 25 ° C. and a hydroxyl value of 80 mgKOH / g.

Production Example 3
The same treatment as in Production Example 1 was performed except that a polyethylene glycol-polypropylene glycol block copolymer (120 g) having a molecular weight of 1200 was used instead of polyethylene glycol (100 g) having a molecular weight of 1000 and lithium perchlorate was changed to 12 g. . The product had a viscosity of 3,900 mPa · s / 25 ° C. and a hydroxyl value of 80 mgKOH / g.

[Production of antistatic agent (modified urethane polymer)]

Example 1
The product obtained in Production Example 1 (200 g), isophorone diisocyanate (44.4 g) and dibutyltin dilaurate (0.01 g) were added to a 1 liter four-necked flask, and a urethanization reaction was performed at 80 ° C. for 4 hours. As a result, a modified urethane polymer was obtained. Then, 104.7 g of ethyl acetate was added and diluted (solid content: 70% by weight, viscosity: 340 mPa · s / 25 ° C.). The weight average molecular weight of the modified urethane polymer was 1880, the isocyanate group content was 3.13 wt (%) / solid content, and the Li atom content was 7.4 wt%.

Example 2
Instead of the product obtained in Production Example 1, the same procedure as in Example 1 was carried out except that the product obtained in Production Example 2 was used, and a modified urethane polymer diluted solution (solid content: 70% by weight) , Viscosity: 460 mPa · s / 25 ° C.).
The modified urethane polymer had a weight average molecular weight of 1890, a terminal isocyanate group content of 3.10% by weight / solid, and a Li atom content of 7.3% by weight.
Met.

Example 3
Instead of the product obtained in Production Example 1, the same procedure as in Example 1 was carried out except that the product obtained in Production Example 3 was used, and a modified urethane polymer diluted solution (solid content: 70% by weight) , Viscosity: 620 mPa · s / 25 ° C.).
The weight average molecular weight of the modified urethane polymer was 1860, the isocyanate group content was 3.10 wt (%) / solid content, and the Li atom content was 7.2 wt%.
Met.

Example 4
The same procedure as in Example 1 was carried out except that 46.7 g of hexamethylene diisocyanate was used instead of 44.4 g of isophorone diisocyanate, and a diluted solution of a modified urethane polymer (solid content: 70.1 wt%, viscosity: 280 mPa · s). s / 25 ° C.).
The weight average molecular weight of the modified urethane polymer was 1780, the isocyanate group content was 4.70% by weight / solid, and the Li atom content was 7.3% by weight.

Example 5
The same procedure as in Example 2 was carried out except that 46.7 g of hexamethylene diisocyanate was used instead of 44.4 g of isophorone diisocyanate, and a diluted solution of a modified urethane polymer (solid content: 70.1 wt%, viscosity: 280 mPa · s). s / 25 ° C.).
The weight average molecular weight of the modified urethane polymer was 1736, the isocyanate group content was 4.80% by weight / solid, and the Li atom content was 7.2% by weight.

Example 6
The same procedure as in Example 3 was carried out except that 46.7 g of hexamethylene diisocyanate was used instead of 44.4 g of isophorone diisocyanate, and a diluted solution of the modified urethane polymer (solid content: 70.1 wt%, viscosity: 360 mPa · s). s / 25 ° C.).
The weight average molecular weight of the modified urethane polymer was 1740, the isocyanate group content was 4.80% by weight / solid, and the Li atom content was 7.2% by weight.

Comparative Example 1
Instead of the product obtained in Production Example 1, the same operation as in Example 1 was performed except that polyethylene glycol (200 g) having a molecular weight of 1000 was used, and a urethane polymer diluent (solid content: 70.1% by weight, Viscosity: 200 mPa · s / 25 ° C.).
The weight average molecular weight of the urethane polymer was 1340, and the isocyanate group content was 6.3 weight (%) / solid content.

Comparative Example 2
Instead of the product obtained in Production Example 1, the same operation as in Example 1 was carried out except that polypropylene glycol (200 g) having a molecular weight of 1000 was used, and a urethane polymer diluent (solid content: 70.1% by weight, Viscosity: 180 mPa · s / 25 ° C.).
The weight average molecular weight of the urethane polymer was 1450, and the isocyanate group content was 5.8% by weight / solid content.

Comparative Example 3
Instead of the product obtained in Production Example 1, the same operation as in Example 1 was carried out except that a polypropylene glycol-polyethylene glycol copolymer (200 g) having a molecular weight of 1200 was used, and a urethane polymer diluent (solid content: 70.2% by weight, viscosity: 200 mPa · s / 25 ° C.).
The weight average molecular weight of the urethane polymer was 1640, and the isocyanate group content was 5.1 weight (%) / solid content.

[Preparation of test adhesive sheet]
Acrylic adhesive solution (Acrylic adhesive composition: 2-ethylhexyl acrylate (79 wt%) / 2-hydroxy acrylate (20 wt%) / acrylic acid (1 wt%), solid content: 30%, molecular weight: 100 In addition, 1.0 g of a diluted solution of the modified urethane polymer produced in Example 1 was added to 50 g of a hydroxyl value: 96 mg KOH / g, acid value: 6 mg KOH / g, solvent: ethyl acetate), and the mixture was mixed with PET. It was applied to one side of a sheet (thickness: 50 μm) and dried at 80 ° C. for 1 minute to produce a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 10 μm.
Moreover, the compounding quantity of the diluted solution of the modified urethane polymer (antistatic agent) manufactured in Example 1 was changed, and the same adhesive sheet was produced.
Furthermore, using the diluted solution of the modified urethane polymer (antistatic agent) produced in Examples 2 to 4 and the diluted solution of the urethane polymer of Comparative Examples 1 to 3, respectively, a test pressure-sensitive adhesive sheet was prepared by the same operation.

[Evaluation test]
The following evaluation tests were performed on the pressure-sensitive adhesive sheet for testing. The results are shown in Table 1. In addition, the comparative example 4 is the adhesive sheet produced by the operation similar to the above except having used the dodecylbenzenesulfonic acid solution (0.5-38g) as an antistatic agent.

1. Adhesive strength Conforms to JIS K 7128.

2. Antistatic (AS) property Adhesive layer surface resistivity (Ω / □), ADVANTEST, digital ultrahigh resistance / microammeter (trade name: R8340 / 8340A) in 23 ° C x 60% RH And measured.

3. Antistatic maintenance property The pressure-sensitive adhesive sheet was allowed to stand in an environment of 50 ° C. and 10% RH for 20 hours and then immersed in water for 24 hours. Thereafter, the surface resistivity of the adhesive layer was measured by the above method.

  The above test results are shown in Table 1 below.

  From Table 1, when the antistatic agent (Examples 1-6) of this invention is mix | blended with an adhesive and an adhesive layer is formed, even if the adhesive layer surface becomes low resistance enough and is exposed to a heat | fever and a water | moisture content, It can be seen that the low electrical resistance is maintained and good antistatic properties are maintained. Moreover, the liquid pot life of the adhesive solution which mix | blended the antistatic agent (Examples 1-6) of this invention satisfy | fills 24 hours (1 day), and should fully respond to industrial continuous production. I understand.

Claims (5)

  An antistatic agent for pressure-sensitive adhesives comprising a polymer compound in which a diol compound to which an alkali metal atom is added and a diisocyanate compound are bonded by a urethane bond (-NHCO-) and having an isocyanate group (-NCO).   The antistatic agent according to claim 1, wherein the diol compound is a condensate of a linear or branched alkylene glycol having 2 to 100 carbon atoms.   The antistatic agent according to claim 1 or 2, having a weight average molecular weight of 500 to 100,000.   The antistatic agent according to any one of claims 1 to 3, wherein the alkali metal atom is a lithium atom.   The antistatic agent according to any one of claims 1 to 4, which is used for an acrylic pressure-sensitive adhesive.