KR100484302B1 - Conductive acrylic-urethane aqueous dispersion and pressure-sensitive adhesive films made therefrom - Google Patents

Abstract

Provided are a conductive acryl-urethane aqueous adhesive which has a surface resistance of 10^10 Ф/cm2 or less and shows an antistatic property, its preparation method and a conductive pressure sensitive adhesive film prepared by using the adhesive. The method comprises the steps of preparing a (meth)acryl group-terminated urethane polymer dispersant represented by the formula 1; mixing 2-85 wt% of the urethane polymer dispersant, 10-97.99 wt% of a C4-C18 alkyl (meth)acrylate monomer and 0.01-5 wt% of a crosslinked oligomer, dispersing the mixture in deionized water, adding a radical initiator to polymerize them to prepare an acryl-urethane water dispersion containing 10-70 wt% of a solid part; and dissolving 0.1-10 parts by weight of a metal in 100 parts by weight of the water dispersion, to prepare a conductive acryl-urethane aqueous adhesive. Preferably the urethane polymer dispersant is prepared by reacting is a polyol having a carboxyl group and a polyol having a molecular weight of 300-5,000 with a polyisocyanate, and reacting the obtained one with a hydroxyalkyl acrylate.

Description

Conductive acrylic-urethane aqueous dispersion and pressure-sensitive adhesive films made therefrom

The present invention relates to a pressure-sensitive adhesive having an excellent antistatic function by adsorbing metal ions on the surface of the acrylic-urethane dispersion particles, the surface resistance of 10 ¹⁰ Ω / ㎠ or less to provide a water-based pressure-sensitive adhesive having an excellent antistatic function The purpose. In addition, to provide an adhesive film of the antistatic function using the same.

The present invention relates to a conductive acrylic-urethane aqueous dispersion and a pressure-sensitive adhesive film produced therefrom, and more particularly, to spherical, conductive, and tacky polymer particles used for the purpose of imparting conductivity or removing chargeability. In addition, another object of the present invention is to provide a pressure-sensitive adhesive film manufacturing technology that is contained in the pressure-sensitive adhesive polymer particles with ion conductivity excellent performance in preventing static charge accumulation.

A pressure-sensitive adhesive is defined as a substance that is tacky at room temperature and adheres to the adherend with a small pressure. Products using these pressure-sensitive adhesives are widely used in our real life, such as various forms of labels, sealants, double-sided tape because of the adhesiveness and convenience. In addition, the adhesive film has been widely applied as a protective material for various liquid crystal monitors, mobile phones, prism sheets, and thin film semiconductor liquid crystal polarizers. In general, pressure-sensitive adhesives are prepared by applying a solvent-type or emulsion pressure-sensitive adhesive to a release sheet having a low surface energy and drying, and laminating the dry pressure-sensitive adhesive to a label base paper. The part with the adhesive component is protected by the release sheet, and the upper part is shaped by a suitable printing method, and then cut into a suitable size. To attach the label to another deposit, remove the release sheet and apply some force to the deposit. When removing the release sheet, the surface energy of the release sheet must be much smaller than the surface energy of the adhesive in order for the adhesive component to fall cleanly without residue.

In general, pressure-sensitive adhesives are classified into solvent-based adhesives, water-based adhesives and hot-melt adhesives depending on the dispersion medium. Hot melt pressure sensitive adhesive has many advantages because it is a solvent-free type, but commercialization is not yet established because it is competing in comparison with the solvent type and the aqueous type in terms of quality and price. Therefore, the pressure-sensitive adhesive is the solvent type and the water-based pressure-sensitive adhesive is the most widely used. Recently, due to environmental regulations, the conversion from the solvent-type adhesive to the water-based adhesive is sought, but the aqueous adhesive is still inferior to the solvent-type adhesive. Recently, a technique of using a polymer emulsifier to induce crosslinking in particles by two-step polymerization process to improve water resistance, which is a disadvantage of an aqueous adhesive, exhibits high adhesive strength and cohesive force without containing an external crosslinking agent and overcomes water resistance. [Polymer Science and Technology, 1995, 6, 585, 'Recent Trends in Adhesive Development']

On the other hand, with the development of the information industry, it is becoming more functional and miniaturized, and advanced technology is required for the management and protection of various electronic components. The materials and components used to make ultra-precision parts or products such as semiconductors and optical transmission devices must be protected from static electricity and dust. In order to prevent dust generation, clean room of less than 1,000 class is used, but if the protective film of electronic parts is not charged, the static electricity generated from the detaching process and labeling process of the protective film is prevented. It cannot be removed. In addition, semiconductor devices that react sensitively from static electricity are defined as so-called ESD sensitive items, and attention is required from production to follow-up. For example, the constant voltage generated from a protective film using a solvent-type or emulsion adhesive is from 100,000 volts (V) to thousands of volts. Locally high heat is generated and the junctions are destroyed.

Therefore, there is a demand for development of an adhesive having an antistatic function. The method of imparting an antistatic function to the pressure-sensitive adhesive is widely known by introducing and mixing a substance having a conductive component such as metal powder or carbon particles (US Pat. No. 4,749,612). However, since the pressure-sensitive adhesive using conductive particles must be used at a high concentration in order to exhibit the charging performance, the pressure-sensitive adhesive performance is not only lowered, but also has the disadvantage of leaving a residue on the adherend during desorption.

Water-based pressure-sensitive adhesives have not only an environmentally friendly point of view, but also have various functions using adsorption performance on the surface. In the present invention, in order to solve the above problems, it was conceived that a pressure-sensitive adhesive excellent in imparting conductivity and antistatic performance by combining metal ions on the surface of the aqueous particles.

In order to achieve the above object, the conductive acrylic-urethane water dispersion of the present invention is a (meth) acryl group represented by the following formula (1) 2 to 85% by weight of the urethane polymer dispersant, the alkyl (meth) having 4 to 18 carbon atoms 10 to 97.99% by weight of the acrylate monomer and 0.01 to 5% by weight of the crosslinked oligomer are mixed and dispersed in deionized water, followed by polymerization with a radical initiator to prepare an acrylic-urethane dispersion having a solid content of 10 to 70% by weight. It is characterized by being prepared by dissolving 0.1 to 10 parts by weight of the metal salt with respect to 100 parts by weight.

[Formula 1]

(Where X is hydrogen or methyl group, Z is alkylene group, Y is alkylene oxide, alkylene ester, alkylene carbonate, R 'is selected from methyl group or ethyl group, R is selected from hydrogen or methyl group and n is Any one selected from an integer of 1 to 100.)

The conductive urethane-acrylic water dispersion of the present invention synthesizes a urethane polymer having a molecular weight of 1,000 to 10,000 terminal (meth) acrylate introduced in the first step, and then performs a water dispersion polymerization reaction to impart tackiness in the second step. It is to provide a water-based pressure-sensitive adhesive having an excellent antistatic function, including the process of increasing the conductivity by dissolving the metal salt in the third step.

Looking at the present invention in more detail as follows.

The conductive acrylic-urethane water dispersion of the present invention is 2 to 85% by weight of the urethane polymer dispersant in which the (meth) acryl group represented by Chemical Formula 1 is end-bonded, and 10 to 97.99 weight of the alkyl (meth) acrylate monomer having 4 to 18 carbon atoms. % And 0.01 to 5% by weight of the crosslinked oligomer are mixed and dispersed in deionized water, followed by polymerization with a radical initiator to prepare an acrylic-urethane dispersion having a solid content of 10 to 70% by weight, and 0.1 to 100 parts by weight of the aqueous dispersion. It is characterized in that it is prepared to dissolve and adsorb 10 parts by weight of the metal salt.

The conductive acrylic urethane aqueous dispersion is synthesized in one step a urethane polymer dispersant in which a terminal (meth) acrylate group having a molecular weight of 1,000 to 10,000 is introduced, two steps of an acrylic-urethane dispersion polymerization reaction to impart tackiness, And it is obtained by a three step process of dissolving the metal salt to adsorb on the surface in order to increase the conductivity.

In the first step, a urethane polymer is synthesized by reacting a polyol having a carboxyl group and a polyol having a molecular weight of 300 to 5,000 with a polyisocyanate in order to introduce a (meth) acrylate group and hydrophilicity at a terminal thereof. And neutralized with tertiary amine.

Synthesis of urethane polymers in which carboxyl groups and (meth) acrylate groups are introduced at the terminals is well known. For example, US Pat. No. 5,910,536 first obtains an isocyanate terminated prepolymer, followed by reaction of a hydroxy-alkyl (meth) acrylate monomer. Isocyanate terminated prepolymers are synthesized in the urethane reaction with polyols and polyisocyanates having at least two isocyanate groups.

Preferred polyols are polyols having a molecular weight of 300 to 5,000. Examples of the polyol include polyetherdiol, polyesterdiol and the like, and as the polyol having a carboxyl group, bis (hydroxymethyl) propanoic acid, bis (hydroxymethyl) butanoic acid and the like are used.

Preferably, the polyisocyanate has at least two isocyanate groups, and representative polyisocyanates include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, bis (4-isocyanate hexyl) methane, bis (4-isocyanatephenyl) methane, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and the like.

In general, the OH, or NCO / OH molar ratio, of polyols to NCOs of polyisocyanates is suitably from 1 to 1.5. In addition, an organic tin acid ester, ie, dibutyltin dilaurate, dioctyltin dilaurate, or the like is used as a catalyst for smoothing the reaction in the urethane reaction.

2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate is reacted with a prepolymer having an isocyanate end group to synthesize a urethane polymer having a (meth) acrylate group as a end group.

In the second step, the urethane dispersant bonded to the (meth) acrylate group end group synthesized in the first step, an alkyl (meth) acrylate monomer having 4 to 18 carbon atoms, and a small amount of crosslinking oligomer are mixed and dispersed in deionized water. , A radical initiator is added to prepare an acrylic-urethane dispersion.

The alkyl (meth) acrylate has 4 to 18 carbon atoms and includes 2-ethylhexyl acrylate, butyl acrylate, isooctyl acrylate, octadecyl acrylate, and the like.

The crosslinking oligomer is a polyfunctional acrylate including 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and polyethylene oxide dimethacrylate.

 As the radical initiator, thermal initiators and redox initiators may be used, and as radical initiators, water-soluble ammonium peroxide, sodium peroxide, potassium peroxide, benzoyl peroxide, azobisisobutyronitrile, etc. may be used. And redox initiator may be used as a mixture of ammonium persulfate and sodium bisulfite, but is not limited thereto. The polymerization induces monomer polymerization at a temperature between 40 and 80 ° C. while stirring the aqueous dispersion of the mixed solution above depending on the decomposition temperature of the radical initiator.

As a method of confirming the completion of the polymerization of the present invention, the smell of the monomer used in the pressure-sensitive adhesive can be felt as a sense of smell disappears, and by analyzing the IR spectrum is a peak indicating a conjugated (conjugation) double bond The strong absorption band of 1640 ~ 1650 cm ^-1 disappeared to confirm that the conjugated double bond disappeared.

The third step process uses a group of metal ionic salts to impart conductivity to the acrylic-urethane dispersion prepared in the second step. At this time, the ion salt is adsorbed by the electron donating group on the surface of the acryl-urethane dispersion particle. Alkali metal or alkaline earth metal salts are generally used as the ion salt for imparting conductivity. For example, NaI, NaSCN, BaCF ₃ SO ₃ , NaBr, NaClO ₄ , LiCl, LiNO ₃ , LiCF ₃ SO ₃ , LiSO ₄ , LiOH and KOH and the like are used, and double lithium salts are preferred, and lithium nitrate (LiNO ₃ ) is more preferred.

In the target compound, the conductivity increases with the content of the metal ion salt group in the third step, and the surface resistance of the pressure sensitive adhesive is 10 ⁷ Ω / cm 2 or less, thereby showing an excellent antistatic effect.

The present invention may include additives such as a tackifying agent, an antioxidant, a pigment, a thickener, and an organic solvent, which are used in a conventional pressure-sensitive adhesive to improve adhesion performance to a conductive acrylic-urethane aqueous dispersion. And a mixing ratio of the acrylic-urethane aqueous dispersion is 1:99 to 90:10.

The taeki Purifying agent may use a Ficoll light (Piccolyte ^TM), poral (Foral ^TM), pen Tallinn (pentalyn ^TM), etc. to be produced in a hydrogenated rosin ester, heokyul Manresa (Hercules Co.).

The antistatic film is produced by applying the conductive acrylic-urethane water dispersion of the present invention to a film such as polyimide, polyphenylenesulfide, polyethylene terephthalate, polyethylene, polypropylene, or the like. The coating process is carried out by knife coating, mayer coating, roll coating processes which are commonly used, followed by an appropriate drying process.

Hereinafter, the present invention will be described in more detail with reference to the following Examples, which are not intended to limit the scope of the present invention.

[Production Example 1]

(Meth) acrylate terminal urethane polymer synthesis.

120.46 g of polyethyleneglycol-b-polypropyleneglycol-b-polyethyleneglycol (Aldrich Chemical, molecular weight 2900, ethyleneglycol 40% by weight), 66.2g methyl Add ethyl ketone, 6.34 g polypropylene glycol (Aldrich Chemical, Molecular Weight 425), 2.83 g bis (hydroxymethyl) propionic acid, 28.0 g isoprone diisocyanate, 0.1 g dibutyne dilaurate, and add 80 The temperature is raised to ° C. After reacting for 48 hours in a nitrogen atmosphere, 3.0 g of 2-hydroxyethyl acrylate is added and the reaction is maintained for 4 hours. In order to neutralize, 2.05 g of triethylamine was added and the reaction was carried out for 1 hour. The prepared dispersant molecular weight was 6300 in number average molecular weight.

[Production Example 2]

Manufacture of acrylic urethane dispersion

114 g of the (meth) acrylate-terminated urethane polymer oligomer, 40 g of 2-ethylhexyl acrylate, and 0.5 g of 1,6-hexanediol diacrylate were mixed well, and then added to 300 g of deionized water with stirring to disperse the aqueous dispersion. Manufacture. 1.0 g of ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), a redox initiator, 40 g of red bisulfite (NaHSO ₃ ) 0.8 g, and 3.0 g of sodium bicarbonate (NaHCO ₃ ) were added to the reaction mixture. The polymerization was induced. The prepared water dispersion was 350 micron particle diameter measured by the Marlbourne particle sizer, the solid content was 28.0%.

Hereinafter, the effects of the present invention will be described through examples and comparative examples according to the present invention. First, look at the analysis method of the physical properties according to the composition of the present invention.

1. Measurement of surface resistance

The resulting antistatic adhesive was applied to a polyethylene terephthalate film at 75 microns and dried at 120 ° C. for 7 minutes. The specimen measured at 25 microns in thickness was used with an ultra-insulating resistance meter under conditions of 25 ° C. and 55% humidity of ASTM D conditions. The surface resistance value (ohm / cm <2>) after pressure 500V and 1 minute is measured.

2. Peel Strength Test

Prepare specimens by cutting them to 25 mm and 250 mm in width and length using kraft paper by the method according to Korean Industrial Standard KS A1107. The surface of the test plate is lightly ground with water-resistant abrasive paper and then thoroughly washed with isopropanol. Apply the adhesive on the washed test plate using an auto coater and apply it to the test piece with an automatic coater, coat it with a roller five times, and then dry it for 3 minutes at 100 ° C. One reciprocation was pressed at a speed of 30 cm / min. After about 30 minutes, the average value of the adhesive strengths measured on three specimens at a speed of 300 ± 30 mm / min at room temperature using a 180-degree peel test instrument is obtained.

3. Holding Strength

According to the Korean Industrial Standard KS A1107, the specimens are cut to 25 mm and 250 mm and 3 pieces are prepared. Apply the polymer to the test piece using a pressure-sensitive adhesive and coat it with a roller for 5 round trips, and then dry it for 3 minutes at 100 ° C. After about 30 minutes, one end of the test plate is fixed with a detent and the test plate and the test piece are folded so that the test piece is suspended vertically, and a weight of 1 kg is suspended at the end of the folded portion and the time until the test piece is dropped from the test plate is measured at room temperature.

4. Initial Adhesion

Four specimens of 10-15 mm in width and 300 mm in length were used for the test piece. The ball was made of two kinds of high-carbon chromium bearing steel specified in KS D 3525. The nominal size of the ball is used from 1/16 to 1, and the angle of the inclined plate is 30 degrees. The polymerized adhesive was applied to the test piece, coated with a roller five times, and then dried for 3 minutes at 100 ° C. The test piece was placed on a ball rolling test device, and then the polyester film was attached to the auxiliary runway. The ball is washed with isopropanol, and then the size of the ball is changed to find the largest ball in the measuring section that stops completely (the ball will not move for more than 5 seconds). Roll the ball three times in total to find the largest ball. The measurement was carried out at room temperature and the initial adhesive force (ball number) can be calculated as 32 times its nominal ball.

The following describes the examples and comparative examples and the physical properties thereof.

[Examples 1 to 6 and Comparative Examples]

Conductive Acrylic-Urethane Dispersion Adhesive Composition

In Examples 1 to 6, only the concentration of lithium ions is changed as shown in Table 1 below to prepare and evaluate the conductive acrylic-urethane dispersion and pressure-sensitive adhesive film, and the comparative example does not add a lithium compound.

Table 1

¹ Acrylic Carbide Thickener of Union Carbide

In the above examples and comparative examples, before adding the aqueous lithium ion solution, polyfob 104 ^TM was added to a solution of an acrylic urethane aqueous dispersion to adjust viscosity. Lithium nitrate and lithium hydroxide were added to the aqueous solution to have the above concentration, and slowly stirred. The conductive acrylic urethane water dispersible adhesive thus prepared was applied to a polyethylene terephthalate film at 75 microns and dried at 120 ° C. for 7 minutes. The antistatic film obtained by the above Examples and Comparative Examples was measured using the following test method and the results are summarized in Table 2.

TABLE 2

(In the coating test of Table 2, after applying the antistatic adhesive obtained in the polyethylene terephthalate film using # 12 Meyers bar, and left at room temperature for 20 seconds, if no pinhole occurs ◎, pinhole within 10 seconds to 20 seconds ○ when it occurs, and when a pinhole occurs as soon as coating occurs, it is indicated by △.)

In Examples 1 to 6 according to the above composition according to the present invention, as shown in the table, it is possible to obtain an adhesive product having excellent antistatic performance and excellent coating property, adhesive force, holding force, etc. and having various functionalities. When the lithium salt of the comparative example was not added, the surface resistance, adhesive strength, etc. were generally inferior.

Therefore, the present invention forms an acrylic-urethane water dispersion adhesive adsorbed on the surface by dissolving a metal ion salt on the surface, thereby having an antistatic function having a surface resistance of 10 ¹⁰ Ω / ㎠ or less, and having coating property, adhesive force, holding force, and the like. This excellent and versatile adhesive product can be obtained.

The present invention is not limited to the above-described embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (15)

2 to 85% by weight of the urethane polymer dispersant in which the (meth) acryl group of Formula 1 is bonded, 10 to 97.99% by weight of an alkyl (meth) acrylate monomer having 4 to 18 carbon atoms, and 0.01 to 5% by weight of a crosslinking oligomer are mixed. After dispersing in deionized water, a radical initiator is added to polymerize to prepare an acrylic urethane dispersion having a solid content of 10 to 70 wt%, and a conductive acrylic prepared by dissolving 0.1 to 10 parts by weight of a metal salt with respect to 100 parts by weight of the aqueous dispersion. Urethane water-based adhesive. The urethane polymer dispersant in which the (meth) acrylic group is end-bonded to synthesize an isocyanate terminated prepolymer by reacting a polyol having a carboxyl group and a polyol having a molecular weight of 300 to 5,000 and a polyisocyanate and A conductive acrylic urethane-based pressure-sensitive adhesive, characterized in that it has a structure of the following [Formula 1] prepared by reacting with a oxy-alkyl (meth) acrylate monomer. [Formula 1] (Where X is hydrogen or methyl group, Z is alkylene group, Y is alkylene oxide, alkylene ester, alkylene carbonate, R 'is selected from methyl group or ethyl group, R is selected from hydrogen or methyl group and n is Any one selected from an integer of 1 to 100.) The polyol according to claim 2, wherein the polyol having a carboxyl group is at least one selected from bis (hydroxymethyl) propanoic acid or bis (hydroxymethyl) butanoic acid, and a polyol having a molecular weight of 300 to 5,000 is a polyether. A conductive acrylic urethane water-based pressure sensitive adhesive, characterized in that any one or more selected from diol or polyester diol. 3. The polyisocyanate uses polyisocyanates having at least two isocyanate groups, and wherein tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, bis (4-isocyanatehexyl) methane, bis (4-isocyanate) Phenyl) methane, 2,6-toluene diisocyanate or 2,4-toluene diisocyanate, at least one selected from the group consisting of a conductive acrylic urethane-based pressure-sensitive adhesive. The conductive acrylic-urethane-based pressure sensitive adhesive according to claim 2, wherein the hydroxy alkyl (meth) acrylate monomer is at least one selected from 2-hydroxyethyl methacrylate or 2-hydroxyethyl acrylate. The conductive-urethane-based pressure-sensitive adhesive according to claim 2, wherein the NCO / OH molar ratio is obtained by a urethane reaction adjusted to be 1 to 1.5. The method of claim 1, wherein the alkyl (meth) acrylate monomer having 4 to 18 carbon atoms is selected from 2-ethylhexyl acrylate, butyl acrylate, isooctyl acrylate, octadecyl acrylate, and the crosslinking oligomer is 1,4 -Butanediol diacrylate, 1,6-hexanediol diacrylate, polyethylene oxide dimethacrylate, conductive acrylic-urethane-based pressure-sensitive adhesive, characterized in that. The conductive acrylic urethane water-based pressure sensitive adhesive according to claim 1, wherein the radical initiator is water-soluble and is selected from ammonium peroxide, sodium peroxide, potassium peroxide, benzoyl peroxide, azobisisobutyronitrile and redox initiator. The conductive acrylic urethane-based pressure-sensitive adhesive according to claim 1, wherein the metal ion salt is an alkali metal or an alkaline earth metal salt. The conductive acryl salt of claim 9, wherein the metal ion salt is selected from NaI, NaSCN, BaCF ₃ SO ₃ , NaBr, NaClO ₄ , LiCl, LiNO ₃ , LiCF ₃ SO ₃ , LiSO ₄ , LiOH, KOH. Urethane water-based adhesive. A conductive pressure-sensitive adhesive film prepared using the conductive acrylic urethane-based pressure-sensitive adhesive of any one of claims 1 to 10. The method according to any one of claims 1 to 10, A tackifying agent, an antioxidant, a pigment, a thickener, and an organic solvent are used alone or in combination of two or more additives, and the mixing ratio of the additive and the acrylic-urethane aqueous dispersion is 1:99 to 90:10. A conductive acrylic urethane water-based pressure sensitive adhesive, characterized in that. The method of claim 11, wherein a tackifying agent, an antioxidant, a pigment, a thickener, and an organic solvent are used alone or in combination of two or more kinds of additives, and the mixing ratio of the additive and the acrylic-urethane dispersion is 1:99 to 12. 90: The conductive adhesive film, characterized in that between 10. (A) preparing a urethane polymer dispersant in which the (meth) acryl group of Formula 1 is end-bonded; (B) 2 to 85 wt% of the urethane polymer dispersant, 10 to 97.99 wt% of an alkyl (meth) acrylate monomer having 4 to 18 carbon atoms, and 0.01 to 5 wt% of a crosslinking oligomer are mixed and dispersed in deionized water, followed by a radical initiator. Put the polymerization to prepare an acrylic-urethane dispersion of 10 to 70% by weight solid content; (C) dissolving 0.1 to 10 parts by weight of the metal salt with respect to 100 parts by weight of the aqueous dispersion; Method for producing a conductive acrylic urethane water-based pressure-sensitive adhesive, characterized in that consisting of. [Formula 1] The method of claim 14, A urethane polymer dispersant is a polyol having a carboxyl group and a polyol having a molecular weight of 300 to 5,000 and then reacted with a polyisocyanate, followed by reacting with a hydroxyalkyl acrylate.