Pressure-sensitive adhesive tape

Abstract

Provided are a pressure-sensitive adhesive tape, a polishing pad, a method of manufacturing the same, a polishing device and a method of manufacturing a glass substrate. The illustrative pressure-sensitive adhesive tape may be a pressure-sensitive adhesive tape for a polishing material. The pressure-sensitive adhesive tape may be effectively fixed to a surface plate without bubbles, and have excellent resistance to water and a polishing solution and shear strength applied in a polishing process. In addition, the pressure-sensitive adhesive tape may be easily removed from a carrier or surface plate for a polishing pad without residues after polishing.

Claims

1. A polishing pad, comprising: a pressure-sensitive adhesive tape comprising a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer; and a polishing material attached to the first pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape, wherein the polishing material includes a polyurethane-based polishing layer, wherein the pressure-sensitive adhesive tape comprises: a base layer; the first pressure-sensitive adhesive layer located on one surface of the base layer; and the second pressure-sensitive adhesive layer located on the other surface of the base layer, the second pressure-sensitive adhesive layer including an acid-free pressure-sensitive adhesive resin consisting of a lipophilic monomer represented by a compound of Formula 1 at 10 to 30 parts by weight, a (meth)acrylic acid ester monomer other than the lipophilic monomer represented by the compound of Formula 1 at 50 to 99 parts by weight, and a crosslinkable monomer not having a carboxyl group at 0.1 to 10 parts by weight, in a polymerized state, wherein the first pressure-sensitive adhesive layer includes a pressure-sensitive adhesive resin consisting of a (meth)acrylic acid ester monomer other than the lipophilic monomer represented by the compound of Formula 1: ##STR00003## where R.sub.1 to R.sub.3 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms, R.sub.4 is an aryl group having 6 to 25 carbon atoms or —C(═O)—O—X, where X is a methyl group, a tert-butyl group, or a cycloalkyl group having 6 to 12 carbon atoms, at 50 to 99 parts by weight and a crosslinkable monomer at 0.1 to 10 parts by weight in a polymerized state, wherein the acid-free pressure-sensitive adhesive resin is a pressure-sensitive adhesive not having a carboxyl group, wherein the acid-free pressure-sensitive adhesive resin has a molecular weight (Mw) of from 800,000 to 2,000,000, and wherein according to Equation 1:
Gel fraction (%)=B/A×100  [Equation 1] where A is a weight of the pressure-sensitive adhesive layer, and B is a dry weight of an insoluble content obtained after the pressure-sensitive adhesive layer having the weight A is precipitated in ethyl acetate at room temperature for 48 hours, the first pressure-sensitive adhesive layer has a gel fraction according to Equation 1 of 40 to 48%, and the second pressure-sensitive adhesive layer has a gel fraction according to Equation 1 of 65 to 76%.

2. The polishing pad according to claim 1, wherein the first pressure-sensitive adhesive layer includes a pressure-sensitive adhesive resin and a tackifier having a glass transition temperature or softening point of 85° C. or more.

3. The tape polishing pad according to claim 2, wherein the first pressure-sensitive adhesive layer includes the tackifier at 1 to 70 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive resin.

4. The polishing pad according to claim 2, wherein the tackifier is a hydrocarbon resin or hydrogenated product thereof, a rosin resin or hydrogenated product thereof, a rosin ester resin or hydrogenated product thereof, a terpene resin or hydrogenated product thereof, a terpene phenol resin or hydrogenated product thereof, a polymerized rosin resin, or a polymerized rosin ester resin.

5. The polishing pad according to claim 2, wherein the first pressure-sensitive adhesive layer further includes a multifunctional crosslinking agent at 0.001 to 7 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive resin.

6. The polishing pad according to claim 1, wherein the second pressure-sensitive adhesive layer further includes a multifunctional crosslinking agent at 0.01 to 10 parts by weight with respect to 100 parts by weight of the acid-free pressure-sensitive adhesive resin.

7. The tape polishing pad according to claim 1, wherein the second pressure-sensitive adhesive layer further includes a plasticizer at 0.5 to 30 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive resin.

8. A polishing device, comprising: a stand on which a target to be polished is loaded; and a carrier or surface plate for a polishing pad to which the polishing pad of claim 1 is attached by the second pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape.

9. A method of manufacturing a polishing pad, comprising: attaching a polishing material to the first pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the polishing pad of claim 1 at 50° C. or more.

10. The method according to claim 9, wherein the attaching of the first pressure-sensitive adhesive layer to the polishing material is performed by a hot-roll lamination method.

11. A method of manufacturing a polished glass substrate, comprising: polishing a surface of a glass substrate using the polishing pad of claim 1.

12. The method according to claim 11, wherein the polished glass substrate is a glass substrate manufactured in a floating type.

13. The method according to claim 11, wherein the polished glass substrate is a glass substrate for a liquid crystal display (LCD).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of an illustrative pressure-sensitive adhesive tape; and

(2) FIG. 2 is a schematic diagram of a configuration of a polishing device.

ILLUSTRATIVE EMBODIMENTS

(3) Hereinafter, a pressure-sensitive adhesive tape will be described in further detail with reference to Examples and Comparative Examples, but the scope of the pressure-sensitive adhesive tape is not limited to the following Examples.

(4) In the specification, physical properties are evaluated by the following methods.

(5) 1. Evaluation of Initial Adhesive Strength

(6) A sample was prepared by cutting a pressure-sensitive adhesive tape manufactured in Example or Comparative Example to have a horizontal length of 2.54 cm and a vertical length of 12.7 cm. In evaluation of an adhesive strength, as an adherent, an aluminum plate washed with ethyl acetate was used after it was maintained in a constant temperature and constant humidity container at 25° C. and a relative humidity of 50% for 24 hours. A second pressure-sensitive adhesive layer of the sample was attached to the aluminum plate and peeled off at a peel angle of 180 degrees and a peeling rate of 300 mm/min after 30 minutes of the attachment, and a peel strength was measured. The peel strength was defined as an initial adhesive strength.

(7) 2. Change in Adhesive Strength with Elapsed Time

(8) A second pressure-sensitive adhesive layer of the sample used in the manufacture of the initial adhesive strength was attached to the same adherent used in the measurement of the initial adhesive strength, a peel strength was measured by the same method as described above after 7 days of the attachment, and then the measured peel strength was defined as a late adhesive strength. A change with elapsed time was measured by substituting the initial and late adhesive strengths into Equation 2. Conventionally, if the change with elapsed time is within 20%, there can be considered to be no change.
Change in adhesive strength according to time=100×ΔP/P.sub.i  [Equation 2]

(9) In Equation 2, ΔP is an absolute value of a difference between the initial adhesive strength and the late adhesive strength, and P.sub.i is the initial adhesive strength.

(10) 3. Measurement of Gel Fraction

(11) Approximately 0.3 g of a first or second pressure-sensitive adhesive layer manufactured in Example or Comparative Example was taken and added to a stainless 200 mesh iron net, precipitated in ethyl acetate, and maintained in a dark room at room temperature for 2 days. Subsequently, the pressure-sensitive adhesive layer (insoluble content) which was not insoluble in ethyl acetate was taken, and dried in an oven at 70° C. for 4 hours. A weight (dry weight, unit: g) of the resulting product was measured, and substituted into the following Equation, thereby measuring a gel fraction.
Gel fraction(%)=(Measured dry weight)/0.3×100  [Equation 1]

(12) 4. Evaluation of Holding Power

(13) A sample was prepared by cutting a pressure-sensitive adhesive tape manufactured in Example or Comparative Example to have a horizontal length of 25 mm and a vertical length of 50 mm. In evaluation of holding power, as an adherent, an aluminum plate washed with ethyl acetate was used after being maintained in a constant temperature and constant humidity container at 25° C. and a relative humidity of 50% for 24 hours. A first pressure-sensitive adhesive layer of the sample was attached to the aluminum plate, and a 1 kg weight was given to the pressure-sensitive adhesive tape, and then the tape was maintained in a constant temperature container at 80° C. for 1 hour. A holding power was evaluated by measuring a distance the pressure-sensitive adhesive tape slid from the adherent. The holding power can be considered as a criterion of durability and reliability of the pressure-sensitive adhesive tape.

(14) 5. Evaluation of Reworkability

(15) A sample was prepared by cutting a pressure-sensitive adhesive tape manufactured in Example or Comparative Example to have a horizontal length of 440 mm and a vertical length of 500 mm. A second pressure-sensitive adhesive layer of the sample was attached to an aluminum plate, and maintained in a constant temperature and constant humidity container at 80° C. and a relative humidity of 85% for 72 hours. Afterward, the pressure-sensitive adhesive tape was peeled off from the aluminum plate, and then reworkability was evaluated according to the following criteria under the same condition as used in the measurement of the initial adhesive strength.

(16) [Criteria of Evaluating Reworkability]

(17) ◯: when contamination such as a residue of the pressure-sensitive adhesive layer was not observed on the aluminum plate with the naked eye

(18) Δ: when contamination such as a residue of the pressure-sensitive adhesive layer was somewhat observed on the aluminum plate with the naked eye

(19) x: when severe contamination such as a residue of the pressure-sensitive adhesive layer was observed on the aluminum plate with the naked eye

(20) 6. Evaluation of Water Resistance

(21) A sample was prepared by cutting a pressure-sensitive adhesive tape manufactured in Example or Comparative Example to have a horizontal length of 2.54 mm and a vertical length of 12.7 mm. A second pressure-sensitive adhesive layer of the sample was attached to an aluminum plate, and immersed in water at 23° C. for 24 hours. The pressure-sensitive adhesive tape was peeled off from the aluminum plate taken out of water, and a peel strength was measured under the same condition as used in measurement of the initial adhesive strength.

(22) 7. Peel in Polishing

(23) A first pressure-sensitive adhesive layer of a pressure-sensitive adhesive tape manufactured in Example or Comparative Example was stacked and laminated to a porous polyurethane polishing pad using a laminator. Afterward, a second pressure-sensitive adhesive layer was attached to a surface plate for fixing a polishing device. After a glass for an LCD was stacked on a polishing pad, polishing was performed by spraying polishing a slurry onto the glass at a pressure of 50 kPa and 100 rpm for 5 minutes, which is defined as one cycle. Peeling in polishing was evaluated according to the following criteria.

(24) [Evaluation Criteria]

(25) ◯: when peeling was not observed at an interface between the pressure-sensitive adhesive tape and the surface plate even when polishing was repeated 10 cycles

(26) Δ: when peeling was not observed on an edge of the interface between the pressure-sensitive adhesive tape and the surface plate even when polishing was repeated 10 cycles

(27) x: when peeling was not observed at the interface between the pressure-sensitive adhesive tape and the surface plate when polishing was performed 1 cycle

Preparation Example 1

Synthesis of Acrylic Resin (A1)

(28) 95 parts by weight of n-butyl acrylate (n-BA) and 5 parts by weight of acrylic acid were put into a 2 L reactor refluxing nitrogen gas and equipped with a cooling device to facilitate control of temperature. Subsequently, as a solvent, 120 parts by weight of ethyl acetate (EAc) was put thereinto, and nitrogen gas was purged for 60 minutes to remove oxygen. Afterward, a temperature was maintained at 70° C., and 0.02 parts by weight of azobisisobutyronitril (AIBN) was put thereinto as a reaction initiator, and reacted for 8 hours, thereby synthesizing an acrylic resin (A1). A molecular weight of the synthesized resin (A1) was measured by GPC, and the results are summarized in Table 1.

Preparation Example 2

Synthesis of Acrylic Resin (B1)

(29) An acrylic resin (B1) was prepared by performing polymerization as described in Preparation Example 1, except that 49 parts by weight of 2-ethylhexyl acrylate (2-EHA), 30 parts by weight of n-butyl acrylate (n-BA), 10 parts by weight of methyl acrylate, 10 parts by weight of isobornyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate (4-HBA) were put into a reaction vessel as monomers.

Preparation Examples 3 to 7

Synthesis of Acrylic Resins (B2), (B3), (C1) and (C2)

(30) Each resin was prepared by a method as described in Preparation Example 1, except that the weight ratio of the monomer and the ratio of a solvent were changed as shown in Table 1.

(31) TABLE-US-00001 TABLE 1 Preparation Example 1 2 3 4 5 6 7 A1 A2 B1 B2 B3 C1 C2 Composition BA 95 45 30 30 30 44 48 of monomer EHA — 50 49 49 48 52 50 IBOA — — 10 15 10 — — MA — — 10 5 10 — — AA 5 5 — — — 4 — HBA — — 1 1 2 — 2 AIBN 0.02 0.02 0.02 0.02 0.02 0.02 0.02 EAc 120 120 100 100 100 120 140 Mw 78 65 90 85 95 88 60 BA: n-butyl acrylate EHA: 2-ethylhexyl acrylate IBOA: isobornyl acrylate MA: methyl acrylate AA: acrylic acid HBA: 4-hydroxybutyl acrylate AIBN: azobisisobutyronitrile EAc: ethyl acetate Mw: weight average molecular weight(unit: 10,000) Content unit: parts by weight

Example 1

Preparation of Pressure-Sensitive Adhesive Composition

(32) A composition (A) for forming a first pressure-sensitive adhesive layer was prepared by mixing 100 g of an acrylic resin (A1), 0.08 g of N,N,N′,N′-tetraglycidylethylenediamine and 25 g of rosin ester-based tackifier (Foral 85, Hercules), putting 30 g of ethyl acetate, and uniformly stirring to mix the resulting mixture for 10 to 20 minutes. In addition, a composition (B) for forming a second pressure-sensitive adhesive layer was prepared by blending 100 g of acrylic acid (B1) and 0.1 g of a tolylene diisocyanate of trimethylol propane, and uniformly mixing the resulting blend with the composition (A).

(33) Preparation of Pressure-Sensitive Adhesive Tape

(34) A second pressure-sensitive adhesive layer was formed by performing corona treatment on one surface of a poly(ethylene terephthalate) (PET) base layer (thickness: 188 μm, Torei), coating a coating solution prepared by diluting the pressure-sensitive adhesive composition (B) at a suitable concentration in consideration of coatability on the corona-treated surface to have a thickness after drying of 35 μm, and aging the coated solution to suitably perform a crosslinking reaction. Afterward, a first pressure-sensitive adhesive layer was prepared by also performing corona treatment on the other surface of the PET base layer, coating a coating solution prepared by diluting the pressure-sensitive adhesive composition (A) at a suitable concentration in consideration of coatability on the corona-treated surface to have a thickness after drying of 55 μm, and aging the coated solution to suitably perform a crosslinking reaction, thereby manufacturing a pressure-sensitive adhesive tape.

(35) Manufacture of Polishing Pad

(36) A polishing pad was manufactured by thermally laminating the first pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape to a porous polyurethane-based polishing material using a heating laminator.

Examples 2 to 7 and Comparative Examples 1 to 4

(37) Pressure-sensitive adhesive tapes and polishing pads according to Examples 2 to 7 and Comparative Examples 1 to 4 were manufactured by the same method as described in Example 1, except that components of pressure-sensitive adhesive compositions for forming first and second pressure-sensitive adhesive layers were changed as shown in Tables 2 and 3.

(38) TABLE-US-00002 TABLE 2 Example 1 2 3 4 5 6 7 First Kind of resin A1 A1 A1 A2 A2 A2 A1 pressure- Content of 100 100 100 100 100 100 100 sensitive resin adhesive Content of 0.08 0.05 0.08 0.08 0.05 0.08 0.08 layer crosslinking agent Content of 25 20 30 20 20 30 25 tackifier Gel fraction 50% 47% 45% 51% 46% 47% 48% Second Kind of resin B1 B2 B3 B1 B2 B3 B1 pressure- Content of 100 100 100 100 100 100 100 sensitive resin adhesive Content of 0.1 0.1 0.1 0.1 0.1 0.1 0.1 layer crosslinking agent Content of — — — — — — 3 plasticizer Gel fraction 68% 70% 75% 67% 71% 76% 65% Content unit: parts by weight crosslinking agent (first pressure-sensitive adhesive layer): N,N,N′,N′-tetraglycidylethylenediamine crosslinking agent (second pressure-sensitive adhesive layer): tolylene diisocyanate addition of trimethylol propane tackifier: rosin ester-based tackifier (Foral 85, Hercules) plasticizer: poly(ethyleneglycol) bis(2-ethyl hexanoate)

(39) TABLE-US-00003 TABLE 3 Comparative Example 1 2 3 4 First Kind of resin A1 A1 A2 A2 pressure- Content of resin 100 100 100 100 sensitive Content of 0.1 0.1 0.1 0.1 adhesive crosslinking agent layer Gel fraction 78% 75% 50% 45% Second Kind of resin C1 C2 C1 C2 pressure- Content of resin 100 100 100 100 sensitive Content of 0.1 0.1 0.05 0.05 adhesive crosslinking agent layer Gel fraction 66% 66% 60% 58% Content unit: parts by weight crosslinking agent(first pressure-sensitive adhesive layer): N,N,N′,N′-tetraglycidylethylenediamine crosslinking agent (second pressure-sensitive adhesive layer): tolylene diisocyanate addition of trimethylol propane

(40) The physical properties measured in Examples and Comparative Examples are summarized and listed in Tables 4 and 5.

(41) TABLE-US-00004 TABLE 4 Example 1 2 3 4 5 6 7 Initial adhesive 200 220 180 200 180 180 150 strength (g/in) Change in adhesive  15  17  12  15  16  13  10 strength with elapsed time (%) Holding power 0.2 m 0.2 m 0.2 m 0.4 m 0.4 m 0.4 m 0.4 m or less or less or less or less or less or less or less Reworkability ◯ ◯ ◯ ◯ ◯ ◯ ◯ Water resistance (g/in) 180 200 170 175 170 160 140 Peeling in polishing ◯ ◯ ◯ ◯ ◯ ◯ ◯

(42) TABLE-US-00005 TABLE 5 Comparative Example 1 2 3 4 Initial adhesive 270 150 350 170 strength (g/in) Change in adhesive  50  29  45  26 strength with elapsed time (%) Holding power detached detached detached detached Reworkability X ◯ X Δ Water resistance (g/in) 280 100 340 150 Peeling in polishing X X X X Detached: the state that the pressure-sensitive adhesive tape was peeled off from the aluminum plate during evaluation of the holding power.