KR20180136674A - Anti-static adhesive composition and protective sheet prepared from the same - Google Patents

Abstract

Provided is an antistatic adhesive composition. According to an embodiment of the present invention, the antistatic adhesive composition is composed of a urethane-based resin formed of polyol and an isocyanate-based compound, and an antistatic agent. A storage elastic modulus measured at 25°C is about 2.0×10^5 to 5.0×10^5 Pa, and that measured at 60°C is about 2.0×10^4 to 5.0×10^4 Pa. According to the present invention, it is possible to produce a protective sheet with enhanced low adhesive properties using the adhesive composition.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an antistatic pressure-sensitive adhesive composition and an antistatic pressure-

The present invention relates to an antistatic pressure-sensitive adhesive composition and a protective sheet made therefrom. More particularly, the present invention relates to a pressure-sensitive adhesive composition comprising a pressure-sensitive adhesive resin and an antistatic agent, and a protective sheet produced therefrom.

In the manufacture of an image display device such as a liquid crystal display (LCD) device, an organic light emitting display (OLED) device, etc., the surface of various structures can be protected with a tacky sheet, for example, before a subsequent processing step or a subsequent bonding step.

The adhesive sheet may be peeled off again for subsequent processing, and static electricity may be generated at the time of peeling to cause disturbance of operation of the structure or the display channel. Therefore, the pressure-sensitive adhesive sheet needs to have an appropriate antistatic property.

Also, when the adhesive force or peeling force of the pressure sensitive adhesive sheet is excessively increased, for example, a display structure such as an OLED element may be damaged at the time of peeling off the adhesive sheet, and residues of adhesive components may be generated.

Further, it is preferable that the pressure-sensitive adhesive sheet stably maintain durability and stain resistance on the structure for a long period of time.

Korean Patent Laid-Open Publication No. 2004-0030919 (Apr. 04, 2004) discloses a method for producing a pressure-sensitive adhesive layer having a low surface resistivity by using an organic salt as an antistatic agent. However, the organic salt is expensive, It may not be secured.

Japanese Patent Laid-Open Publication No. 1994-128539 (Apr. 10, 1994) discloses a method of imparting antistatic properties by blending a polyether polyol with at least one alkali metal salt, but it is impossible to secure sufficient adhesion property as described above .

Korean Patent Publication No. 2004-0030919 Japanese Laid-Open Patent No. 1994-128539

An object of the present invention is to provide an antistatic pressure-sensitive adhesive composition having an improved resistance property, a low sticking property and a mechanical stability.

An object of the present invention is to provide a protective sheet having improved resistance characteristics, low adhesion properties and mechanical stability.

1. Urethane-based resins formed from polyol and isocyanate-based compounds; And an antistatic agent,

The storage modulus measured at 25 ℃ 2.0 × 10 ⁵ to 5.0 × 10 ⁵ Pa, and 2.0 × 10 is the storage modulus measured at 60 ℃ ⁴ to 5.0 × 10 ⁴ Pa of, antistatic pressure sensitive adhesive composition.

2. The antistatic pressure-sensitive adhesive composition according to 1 above, wherein the polyol has a weight average molecular weight of 2,000 or less.

3. The antistatic pressure-sensitive adhesive composition according to 2 above, wherein the polyol comprises a silicon (Si) -based polyol.

4. The antistatic pressure-sensitive adhesive composition according to 1 above, wherein the ratio of the weight of the polyol to the weight of the isocyanate-based compound is 4 to 10 times.

5. The antistatic pressure-sensitive adhesive composition according to item 1 above, wherein the antistatic agent comprises a fluorine anion solid.

6. The antistatic pressure-sensitive adhesive composition according to 5 above, wherein said antistatic agent comprises a salt of a metal cation and a fluorine-containing anion.

7. The antistatic pressure-sensitive adhesive composition according to 6 above, wherein said fluorine-containing anion comprises a (bis) fluorosulfonylimide anion.

8. The antistatic pressure-sensitive adhesive composition according to 1 above, further comprising an organometallic catalyst.

9. A protective sheet formed from the antistatic pressure-sensitive adhesive composition according to any one of the above 1 to 8.

10. The protective sheet according to the above 9, which is provided for protecting the display element surface of the display panel.

The antistatic pressure-sensitive adhesive composition according to the embodiments of the present invention described above satisfies a predetermined storage elastic modulus according to the temperature range and can prevent the damage of the object and the residue of the sticky component due to the low sticking property upon peeling. In addition, since it has improved aging stability, it can prevent bubbles and peeling, and can maintain stable durability for a long period of time.

In addition, the antistatic pressure-sensitive adhesive composition may include, for example, a fluorine anion solid, and may have an improved antistatic property.

The antistatic pressure-sensitive adhesive composition according to the exemplary embodiments can be applied to, for example, an organic light-emitting display (OLED) panel to provide a protective sheet with improved low sticking and antistatic performance.

1 to 3 are sectional views for explaining a display panel or an image display device to which a protective sheet according to exemplary embodiments is applied.

According to the embodiments of the present invention, the antistatic pressure-sensitive adhesive composition includes a urethane-based resin and an antistatic agent and can satisfy a predetermined storage elastic modulus range according to a temperature range. The antistatic pressure-sensitive adhesive composition can be effectively applied to, for example, a low-adhesion, antistatic protective sheet of an image display apparatus.

Hereinafter, embodiments of the present invention will be described in detail.

≪ Antistatic pressure-sensitive adhesive composition >

The antistatic pressure-sensitive adhesive composition according to the embodiments of the present invention (hereinafter abbreviated as pressure-sensitive adhesive composition) may include a urethane-based resin and an antistatic agent.

The urethane-based resin can be obtained by curing a polyol and an isocyanate-based compound.

According to exemplary embodiments, the polyol may comprise a polyfunctional polyol having a weight average molecular weight (Mw) of 2,000 or less. In some embodiments, the polyol may comprise a bifunctional polyol having a weight average molecular weight (Mw) of 2,000 or less. As a result, the pressure-sensitive adhesive composition is reinforced with low-sticking properties, and it is possible to suppress damage to the residue and the object in the re-peeling process.

Non-limiting examples of the polyol include a polycarbonate polyol, a polyester polyol, and a polyether polyol. These may be used alone or in combination of two or more.

For example, the polycarbonate polyol may comprise a condensate of a polyol compound and a carbonic acid diester-based compound. The polyol compound may be at least one selected from the group consisting of ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl- Propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, , 8-octanediol, 1,8-decanediol, octadecanediol, and the like. These may be used alone or in combination of two or more.

The carbonic acid diester-based compound may include dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate and the like. These may be used alone or in combination of two or more.

The polycarbonate polyol may also comprise a copolymer with the condensate and additional compounds.

The polyester polyol may include, for example, a condensate with the polyol compound and the organic acid-based compound described above.

For example, the organic acid-based compound is selected from the group consisting of succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, terephthalic acid, phthalic acid, isophthalic acid, 4-naphthalene dicarboxylic acid, anhydrides thereof, and the like. These may be used alone or in combination of two or more.

The polyether polyol may include, for example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.

In some embodiments, a silicone (Si) series polyol may be used as the polyol. In this case, as the main chain is extended by the silicon atoms, the peeling property of the pressure-sensitive adhesive composition or the protective sheet can be further improved.

For example, the silicone-based polyol may include a compound having a repeating unit represented by the following formula (1) and having a hydroxyl group at both terminals. For example, the molecular weight of the polyol can be adjusted by controlling the number of repeating units of formula (1).

[Chemical Formula 1]

In Formula 1, R ₁ and R ₂ each independently represent an alkyl group having 1 to 5 carbon atoms. In one embodiment, R ₁ and R ₂ may each be a methyl group.

The isocyanate-based compound may include a polyfunctional isocyanate compound that can be used for the urethanization reaction, for example, a polyfunctional aliphatic isocyanate compound, a polyfunctional alicyclic isocyanate, and a polyfunctional aromatic isocyanate compound. These may be used alone or in combination of two or more.

Examples of the polyfunctional aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3 -Butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and the like.

Examples of the polyfunctional alicyclic isocyanate compound include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane Diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanate methyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane and the like.

Examples of the polyfunctional aromatic isocyanate compound include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4 Tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, and 4,4'-diphenyl ether diisocyanate.

In some embodiments, the ratio of the weight (e.g., weight) of the polyol to the weight (e.g., weight) of the isocyanate-based compound in the urethane-based resin may be about 4 to 10 times .

When the weight of the polyol is less than 4 times the weight of the isocyanate compound, the low adhesion property of the protective sheet produced from the pressure-sensitive adhesive composition may not be sufficiently realized and the durability may be lowered. If the weight of the polyol exceeds 10 times the weight of the isocyanate-based compound, the adhesion of the protective sheet may be excessively reduced.

The antistatic agent may comprise a metal-containing ionic solid. In exemplary embodiments, the antistatic agent may comprise a fluorine anion solid.

In this case, the antistatic agent may include a metal cation and a salt of a fluorine-containing anion. Examples of the metal cations include alkali metal cations such as lithium cations.

In some embodiments, the fluorine containing anion may comprise a (bis) fluorosulfonylimide anion.

By using the above-described fluoro anion solids, excellent resistance characteristics and antistatic properties can be realized even in a small amount. In some embodiments, the antistatic agent in the total weight of the pressure-sensitive adhesive composition solids may be included in an amount of about 0.1 to 5% by weight.

If the content of the antistatic agent is less than about 0.1% by weight, sufficient antistatic properties may not be realized. If the content of the antistatic agent exceeds about 5% by weight, precipitation, bubbling or peeling of the antistatic agent may be caused.

In addition, the use of the solid salt containing the (bis) fluorosulfonylimide anion can improve the compatibility with the urethane-based resin including the polyol. In addition, it is possible to prevent side effects such as leakage and denaturation in a high-temperature / high-humidity environment generated when a liquid type ionic compound is used.

In some embodiments, the pressure sensitive adhesive composition may further comprise a catalyst for promoting the cure or crosslinking reaction of the polyol and the isocyanate-based compound.

The catalyst may include an organometallic compound in consideration of compatibility with a polyol. Non-limiting examples of such catalysts include iron acetylacetonate, iron 2-ethylhexanoate, dibutyl tin dichloride, dibutyl tin oxide, dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin Sulfite, tributyltin methoxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, dioctyltin dilaurate, tributyltin chloride, tributyltin trichloroacetate, di Butyl titanyl dichloride, tetrabutyl titanate, butoxy titanium trichloride, zirconium naphthenate, and zirconium acetylacetonate. These may be used alone or in combination of two or more.

The catalyst may be included in an amount of about 0.01 to 0.1% by weight based on the total weight of the solid content of the pressure-sensitive adhesive composition. When the content of the catalyst is less than 0.01% by weight, sufficient crosslinking or hardening may not be obtained. If the content of the catalyst exceeds about 0.1% by weight, precipitation or sheet peeling may occur.

According to exemplary embodiments of the present invention, the pressure-sensitive adhesive composition may have a storage elastic modulus at 25 캜 of about 2.0 10 ⁵ to 5.0 10 ⁵ Pa. For example, the storage modulus can be measured at a frequency of 1 Hz.

The storage elastic modulus at 25 ℃ is about 2.0 × 10 ⁵ Pa less than. The durability and peel resistance of the pressure-sensitive adhesive sheet or protective sheet formed from the pressure-sensitive adhesive composition at room temperature may be excessively lowered. When the storage elastic modulus at 25 캜 exceeds about 5.0 × 10 ⁵ Pa, the low adhesive property at room temperature of the pressure-sensitive adhesive sheet or the protective sheet may not be substantially realized.

According to an exemplary embodiment, the pressure-sensitive adhesive composition can have from about 2.0 × 10 ⁴ to 5.0 × 10 ⁴ Pa of a storage modulus at 60 ℃ (e.g., at 1 Hz frequency condition). By satisfying the storage elastic modulus within the above range at 60 캜, it is possible to maintain an appropriate adhesive strength at a high temperature while realizing a low adhesive property at room temperature. Therefore, lifting and peeling of the pressure-sensitive adhesive sheet or the protective sheet during prolonged use in a high-temperature and high-humidity environment can be prevented, and the stability over time can be improved.

The pressure-sensitive adhesive composition may further include additional agents within a range not lowering the antistatic property and the low-pressure-sensitive property.

For example, the pressure-sensitive adhesive composition may further include additional agents such as a solvent, an antioxidant, a corrosion inhibitor, a leveling agent, a surface lubricant, a dye, a pigment, a defoamer, a filler and a light stabilizer.

As described above, the pressure-sensitive adhesive composition according to the exemplary embodiments has an improved low-adhesive property, so that it is possible to prevent damage to the object and occurrence of residue of adhesive residue during re-peeling. In addition, it is possible to appropriately secure the required aging stability and mechanical reliability when applied as a protective sheet.

<Protective sheet, display panel, image display device>

1 to 3 are sectional views for explaining a display panel or an image display device to which a protective sheet according to exemplary embodiments is applied.

Referring to FIG. 1, the above-described pressure-sensitive adhesive composition is applied on at least one side of the base layer 60, and the pressure-sensitive adhesive layer 70 may be formed through, for example, a drying and / or curing process. The pressure-sensitive adhesive composition may be formed, for example, by a coating method such as roll coating, gravure coating, reverse coating, spray coating, air knife coating or die coater.

The substrate layer 60 may include, for example, plastic, paper, metal film, non-woven fabric, and the like. In one embodiment, the substrate layer 60 may comprise a plastic film such as a polyester-based resin, a polyamide-based resin, a polyimide-based resin, a polyolefin-based resin, a polyethylene terephthalate (PET)

Accordingly, a protective sheet in which the base layer 60 and the adhesive layer 70 are laminated can be produced, and the protective sheet can have low adhesion and antistatic property through the pressure-sensitive adhesive composition.

In some embodiments, on the upper and lower surfaces of the adhesive layer 70 of the substrate layer 60, respectively. For example, after removing the base layer 60 formed on the lower surface of the adhesive layer 70, the exposed surface of the adhesive layer 70 can be adhered to the display panel 50. Accordingly, the protective sheet may be provided as a surface protective sheet of the display panel 50. [

The display panel 50 may include, for example, a thin film transistor (TFT) substrate and a display element (for example, an OLED element or an LCD element) formed on the TFT substrate.

Referring to FIG. 2, the protective sheet may be peeled from the display panel 50 to laminate additional optical members or functional layers on the display panel 50.

As described above, the pressure-sensitive adhesive composition has an excellent antistatic property and a low adhesive peeling property, so that the pressure-sensitive adhesive composition can be peeled off without damaging the display device of the display panel 50. Further, since the pressure-sensitive adhesive composition has an improved stability over time, the display panel 50 can be protected by blocking the occurrence of lifting, bubbles, and the like after adhering to the display panel 50.

Referring to FIG. 3, the functional structure 80 may be laminated on one side of the display panel 50 from which the protective sheet is peeled off. The functional structure 80 may include optical structures such as a polarizing plate, a retardation film, a hard coating layer, a window film, and the like. In some embodiments, the functional structure 80 may include a touch sensor or touch screen panel.

When the protective sheet is directly applied to the display panel 50 as described with reference to FIGS. 1 to 3, in order to prevent disturbance or damage of the display device due to static electricity or adhesive residue, for example, An improved low adhesion property may be required compared to a protective sheet.

Accordingly, a protective sheet having both an antistatic property and a low adhesive property can be manufactured and applied using a pressure-sensitive adhesive composition that satisfies the storage elastic modulus and composition according to the exemplary embodiments.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. It will be apparent to those skilled in the art that various changes and modifications can be made to the embodiments within the spirit and scope of the appended claims.

Examples and Comparative Examples

A polyfunctional isocyanate compound, a polyfunctional polyol, dibutyltin dilaurate and an antistatic agent as catalysts were added to a 2 L three-necked flask equipped with an electronic stirrer, a heating mantle, a cooling tube and a temperature controller, ) And stirred. During the stirring, the reaction temperature was raised to 60 DEG C through self-heating and the reaction was maintained for 5 hours to prepare a pressure-sensitive adhesive composition.

The prepared pressure-sensitive adhesive composition was coated on one side of a PET film (75 μm), dried in an oven at 80 ° C. for 2 minutes, and then a PET film (50 μm) treated with a silicone release treatment was bonded on the coating layer to form a protective sheet .

Example
One Example
2 Example
3 Comparative Example
One Comparative Example
2 Comparative Example
3 Isocyanate
System compound 22 22 22 22 22 22 Polyol 85
(KF-6000) 95
(KF-6000) 180
(KF-6001) 70
(KF-6000) 320
(KF-6002) 510
(KF-6003) catalyst 0.04 0.04 0.04 0.04 0.04 0.04 Antistatic agent 5 5 10 5 17 26 solvent 120 120 200 120 350 530 1) Isocyanate compounds:
Isophorone diisocyanate (IPDI, molecular weight = 220)
2) Polyol
KF-6000 (molecular weight = 933, Shin-Etsu)
KF-6001 (molecular weight = 1800, Shin-Etsu)
KF-6002 (molecular weight = 3200, Shin-Etsu)
KF-6003 (molecular weight = 5090, Shin-Etsu)
3) Catalyst: dibutyl tin dilaurate
4) Antistatic agent: Lithium bis-fluorosulfonylimide
5) Solvent: methyl ethyl ketone

Experimental Example

1) Measurement of storage modulus

Circular test pieces having a diameter of 25 mm and a thickness of 1 mm were prepared from the adhesive layer side of the protective sheet of Examples and Comparative Examples. The storage elastic modulus (G ') at 25 ° C and 60 ° C was measured (frequency: 1 Hz) through a torsional shear method using a dynamic viscoelasticity meter (MCR300, PSICA).

2) Glass peel force

The protective sheets of Examples and Comparative Examples were cut into a size of 25 mm x 250 mm using a super cutter. Thereafter, a release film (PET film) was peeled off and specimens bonded to a glass plate were prepared. The specimen was fixed to a universal material testing machine (UTM), and then peeled off at 180 ^{° C} at a speed of 300 m / min to measure the peeling force against the glass.

3) Liner (liner) Peel force

The protective sheets of the examples and comparative examples were cut using a super cutter to a size of 25 mm x 250 mm. The release film of the prepared specimen was partially peeled off, fixed on a universal testing machine (UTM), peeled off at 180 ° at a speed of 300 m / min, and peel strength was measured.

4) Surface resistivity

Three points of the adhesive layer included in the protective sheet were measured ten times each using a surface resistivity meter (MCP-HT450, manufactured by Mitsuishi Chemical Co., Ltd.), and the surface resistivity was measured by the average value.

5) Durability over time

The protective sheets of the examples and comparative examples were cut to a size of 300 mm x 220 mm, and a pressure of 5 kg / cm &lt; ² &gt; was applied to a glass of Corning # 1737 to form bubbles or foreign matter. The specimens were allowed to stand in an oven at 60 ° C for 7 days, and then bubbles or peeling occurred. The durability was evaluated according to the following criteria.

<Evaluation Criteria>

Ⓞ: No bubbles or peeling.

○: Bubbles or peeling <5

?: 5 pieces? Bubbles or peeling <10 pieces

X: 10 pieces &lt; bubble &

The evaluation results are shown in Table 2 below.

division Storage elastic modulus (Pa) Glass peel force
(g / 25 mm) Liner peel force
(g / 25 mm) Surface resistivity
(Ω / □) Durability over time 25 ℃ 60 ° C Example 1 2.13 x 10 ⁵ 2.51 x 10 ⁴ 3.2 0.8 8.33 x 10 ⁸ ○ Example 2 3.82 x 10 ⁵ 4.67 x 10 ⁴ 4.9 1.3 8.25 x 10 ⁸ Ⓞ Example 3 4.21 x 10 ⁵ 3.74 x 10 ⁴ 5.6 2.2 6.48 x 10 ⁸ Ⓞ Comparative Example 1 1.61 x 10 ⁵ 1.73 x 10 ⁴ 2.1 0.5 8.56 x 10 ⁸ X Comparative Example 2 7.21 x 10 ⁵ 1.83 x 10 ⁵ 10.5 4.7 8.83 x 10 ⁸ △ Comparative Example 3 8.82 x 10 ⁵ 7.91 x 10 ⁵ 14.2 6.4 5.85 x 10 ⁸ △

Referring to Table 2, in the case of the embodiments satisfying the storage elastic modulus range according to the above-described exemplary embodiments, it was evaluated to have a low peel strength (low sticking property) and an improved durability in time.

In the case of Comparative Example 1 in which the storage elastic modulus was excessively reduced, the peeling force was reduced, but the durability at the time deteriorated excessively. In the case of Comparative Examples 2 and 3 in which the storage elastic modulus was excessively increased as compared with the Examples, the peeling force was remarkably increased and sufficient low adhesive property was not secured.

50: Display panel
60: substrate layer
70: Adhesive layer
80: Functional structure

Claims (10)

Urethane-based resins formed from polyol and isocyanate-based compounds; And an antistatic agent,
The storage modulus measured at 25 ℃ 2.0 × 10 ⁵ to 5.0 × 10 ⁵ Pa, and 2.0 × 10 is the storage modulus measured at 60 ℃ ⁴ to 5.0 × 10 ⁴ Pa of, antistatic pressure sensitive adhesive composition.
The antistatic pressure-sensitive adhesive composition according to claim 1, wherein the polyol has a weight average molecular weight of 2,000 or less.
The antistatic pressure-sensitive adhesive composition according to claim 2, wherein the polyol comprises a silicon (Si) -based polyol.
The antistatic pressure-sensitive adhesive composition according to claim 1, wherein the ratio of the weight of the polyol to the weight of the isocyanate-based compound is 4 to 10 times.

The antistatic pressure-sensitive adhesive composition according to claim 1, wherein the antistatic agent comprises a fluorine anion solid.
The antistatic pressure-sensitive adhesive composition according to claim 5, wherein the antistatic agent comprises a salt of a metal cation and a fluorine-containing anion.
The antistatic pressure-sensitive adhesive composition according to claim 6, wherein the fluorine-containing anion comprises a (bis) fluorosulfonylimide anion.
The antistatic pressure-sensitive adhesive composition according to claim 1, further comprising an organometallic catalyst.
A protective sheet formed from the antistatic pressure-sensitive adhesive composition according to any one of claims 1 to 8.
The protective sheet according to claim 9, which is provided for protecting a display element surface of a display panel.

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