Adhesive composition

Abstract

The present invention provides an adhesive composition that exhibits excellent adhesive force, and can be easily separated by photocuring during a peeling step, in which foaming and lifting are not generated even after a high temperature process.

Claims

1. An adhesive composition comprising: (a) a binder resin comprising a (meth)acrylate resin having a silicon-based functional group and a photoreactive functional group; (b) a photoinitiator; and (c) a multifunctional crosslinking agent, wherein the (meth)acrylate resin comprises a first repeat unit derived from a (meth)acrylate monomer having a silicon-based functional group, and a second repeat unit derived from a crosslinkable monomer having one or more reactive functional groups selected from the group consisting of a hydroxyl group, a carboxy group and a nitrogen-containing functional group, and based on the total weight of the second repeat unit, 20 to 95 wt % of the second repeat unit comprises a photoreactive functional group at side chains, and wherein the first repeat unit is comprised in an amount of 20 to 80 wt %, based on the total weight of the (meth)acrylate resin having the silicon-based functional group and photoreactive functional group.

2. The adhesive composition according to claim 1, wherein the photoreactive functional group is a vinyl group, an allyl group, or a (meth)acryloyl group.

3. The adhesive composition according to claim 1, wherein the (meth)acrylate monomer having a silicon-based functional group comprises at least one of silicone (meth)acrylate represented by Chemical Formulae 2a to 2d: ##STR00003## in the Chemical Formulae 2a to 2d, R.sub.1 to R.sub.4 are each independently, a hydrogen atom, or a C1-10 alkyl group, R.sub.a to R.sub.e are each independently, hydrogen or a methyl group, x, y, z, w and v are each independently, an integer of 1 to 3, and n1 to n4 are each independently, an integer of 1 to 200.

4. The adhesive composition according to claim 1, wherein the crosslinkable monomer having one or more reactive functional groups comprises one or more selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, 2-hydroxy propylene glycol (meth)acrylate, (meth)acrylic acid, crotonic acid, isocrotonic acid, maleci acid, fumaric acid, itaconic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, (meth)acryloylonitrile, N-vinyl pyrrolidone, N-vinyl caprolactam, and 3-(N-methylaminopropyl) methacrylamide.

5. The adhesive composition according to claim 1, wherein the (meth)acrylate resin having a silicon-based functional group and a photoreactive functional group further comprises a third repeat unit derived from a (meth)acrylate-based compound having a C1-12 alkyl group.

6. The adhesive composition according to claim 5, wherein the (meth)acrylate resin having a silicon-based functional group and a photoreactive functional group comprises, based on the total weight of the (meth)acrylate resin, 20 to 40 wt % of the first repeat unit, 20 to 40 wt % of the second repeat unit, and 40 to 60 wt % of the third repeat unit, and based on the total weight of the second repeat unit, 70 to 95 wt % of the second repeat unit comprises a photoreactive functional group at the side chain.

7. The adhesive composition according to claim 1, wherein the (meth)acrylate resin has a weight average molecular weight of 50,000 g/mol to 2,000,000 g/mol, and a glass transition temperature of −100° C. to −5° C.

8. The adhesive composition according to claim 1, wherein the photoinitiator is at least one selected from the group consisting of thioxanthone, 2-chlorothioxanthone, 2-methyl thioxanthone, 2,4-dimethyl thioxanthone, isopropyl thioxanthone, 2,4-dichloro thioxanthone, 2,4-diethyl thioxanthone, 2,4-diisopropyl thioxanthone, dodecyl thioxanthone, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethylester, oxy-phenyl-acetic acid 2[2-hydroxy-ethoxy]ethylester, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide.

9. The adhesive composition according to claim 1, wherein the multifunctional crosslinking agent comprises at least one compound selected from the group consisting of isocyanate compounds, aziridine compounds, epoxy compounds, and metal chelate compounds.

10. The adhesive composition according to claim 1, wherein the composition comprises, based on 100 parts by weight of the binder resin, 0.1 to 40 parts by weight of the photoinitiator, and 0.01 to 30 parts by weight of the multifunctional crosslinking agent.

11. The adhesive composition according to claim 1, further comprising a tertiary amine compound.

12. The adhesive composition according to claim 11, wherein the tertiary amine compound is selected from the group consisting of ethyl-p-dimethyl amino benzoate, methyl-p-dimethyl amino benzoate, 2-ethylhexyl-p-dimethyl amino benzoate, octyl-p-dimethyl amino benzoate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, N,N-dihydroxyethyl-p-toluidine, and a mixture thereof, and is comprised in an amount of 100 to 2000 parts by weight, based on 100 parts by weight of the photoinitiator.

13. An adhesive sheet for temporary fixing comprising a base film, and an adhesive layer, wherein the adhesive layer comprises the adhesive composition according to claim 1.

14. The adhesive composition according to claim 1, wherein the first repeat unit is comprised in an amount of 20 to 40 wt %, based on the total weight of the (meth)acrylate resin having the silicon-based functional group and photoreactive functional group.

15. The adhesive composition according to claim 1, wherein the (meth)acrylate resin has a glass transition temperature of −70° C. to −10° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1a to 1b and FIGS. 2a to 2b respectively show the structure of the cross section of the adhesive sheet for temporary fixing (10) according to one embodiment of the present invention.

(2) FIG. 3 is a photograph observing the appearance of the adhesive sheet for temporary fixing according to Example 1, after heat treatment.

(3) FIG. 4 is a photograph observing the appearance of the adhesive sheet for temporary fixing according to Comparative Example 1, after heat treatment.

EXPLANATION OF REFERENCE NUMERALS AND SYMBOLS

(4) 10: adhesive sheet for temporary fixing 100: base film 200: adhesive layer 300: release film

Detailed Description of the Embodiments

(5) Hereinafter, preferable examples are presented for better understanding of the present invention. However, these examples are presented only as the illustrations of the invention, and the present invention is not limited thereby.

(6) <Preparation of an Adhesive Composition>

Preparation Example 1

(7) Into a reactor in which nitrogen gas is refluxed and a cooling device is installed so as to facilitate temperature control, a monomer mixture consisting of 62.5 g of ethylhexyl acrylate (EHA), 20 g of silicone (meth)acrylate (Silaplane™ FM-0721 manufactured from JNC Corporation), and 17.5 g of hydroxyethyl acrylate (HEA) was introduced. Subsequently, based on 100 g of the monomer mixture, 200 g of ethylacetate (EAc) was introduced as a solvent, and while nitrogen was introduced so as to remove oxygen in the reactor, the mixture was sufficiently mixed at 30° C. for more than 60 minutes. Thereafter, a temperature was raised to and maintained at 65° C., 0.1 g of an initiator of azobisisobutylonitrile (V-60™ manufactured from Wako Pure Chemical Industries) was introduced portionwise to initiate a reaction, and then, polymerization was progressed for 6 hours to prepare a primary reaction product.

(8) To the primary reaction product, 20 g of methacryloyl isocyanate (MOI) (85.5 mol %, based on HEA in the primary reaction product) and 0.08 g of a catalyst (dibutyltin dilaurate, DBTDL) were added, and reacted at 40° C. for 24 hours to introduce UV curable groups at the side chain of the polymer in the primary reaction product, thus preparing binder resin (a-1).

(9) 100 g of the binder resin (a-1) was mixed with 2.0 g of toluene diisocyanate (TDI) as a multifunctional crosslinking agent, 1.2 g of isopropyl thioxanthone (ITX) as a photoinitiator, and 6.0 g of ethyl-p-dimethyl amino benzoate as an amine-based compound to prepare an adhesive composition.

Preparation Example 2

(10) Into a reactor in which nitrogen gas is refluxed and a cooling device is installed so as to facilitate temperature control, a monomer mixture consisting of 52.5 g of ethylhexyl acrylate (EHA), 30 g of silicone (meth)acrylate (Silaplane™ FM-0721 manufactured from JNC Corporation), and 17.5 g of hydroxyethyl acrylate (HEA) was introduced.

(11) Subsequently, based on 100 g of the monomer mixture, 200 g of ethylacetate (EAc) was introduced as a solvent, and while nitrogen was introduced so as to remove oxygen in the reactor, the mixture was sufficiently mixed at 30° C. for more than 60 minutes. Thereafter, a temperature was raised to and maintained at 65° C., 0.1 g of an initiator of azobisisobutylonitrile (V-60™ manufactured from Wako Pure Chemical Industries) was introduced portionwise to initiate a reaction, and then, polymerization was progressed for 6 hours to prepare a primary reaction product.

(12) To the primary reaction product, 20 g of methacryloyl isocyanate (MOI) (85.5 mol %, based on HEA in the primary reaction product) and 0.08 g of a catalyst (dibutyltin dilaurate, DBTDL) were added, and reacted at 40° C. for 24 hours to introduce UV curable groups at the side chain of the polymer in the primary reaction product, thus preparing binder resin (a-2).

(13) 100 g of the binder resin (a-2) was mixed with 2.0 g of toluene diisocyanate (TDI) as a multifunctional crosslinking agent, 1.2 g of isopropyl thioxanthone (ITX) as a photoinitiator, and 6.0 g of ethyl-p-dimethyl amino benzoate as a tertiary amine-based compound to prepare an adhesive composition.

Preparation Example 3

(14) Into a reactor in which nitrogen gas is refluxed and a cooling device is installed so as to facilitate temperature control, a monomer mixture consisting of 37 g of ethylhexyl acrylate (EHA), 25.5 g of butyl acraylte (BA), 20 g of silicone (meth)acrylate (Silaplane™ FM-0721 manufactured from JNC Corporation), and 17.5 g of hydroxyethyl acrylate (HEA) was introduced. Subsequently, based on 100 g of the monomer mixture, 200 g of ethylacetate (EAc) was introduced as a solvent, and while nitrogen was introduced so as to remove oxygen in the reactor, the mixture was sufficiently mixed at 30° C. for more than 60 minutes. Thereafter, a temperature was raised to and maintained at 65° C., 0.1 g of an initiator of azobisisobutylonitrile (V-60™ manufactured from Wako Pure Chemical Industries) was introduced portionwise to initiate a reaction, and then, polymerization was progressed for 6 hours to prepare a primary reaction product.

(15) To the primary reaction product, 20 g of methacryloyl isocyanate (MOI) (85.5 mol %, based on HEA in the primary reaction product) and 0.08 g of a catalyst (dibutyltin dilaurate, DBTDL) were added, and reacted at 40° C. for 24 hours to introduce UV curable groups at the side chain of the polymer in the primary reaction product, thus preparing binder resin (a-3).

(16) 100 g of the binder resin (a-3) was mixed with 2.0 g of toluene diisocyanate (TDI) as a multifunctional crosslinking agent, 1.2 g of isopropyl thioxanthone (ITX) as a photoinitiator, and 6.0 g of ethyl-p-dimethyl amino benzoate as a tertiary amine-based compound to prepare an adhesive composition.

Comparative Preparation Example 1

(17) Into a reactor in which nitrogen gas is refluxed and a cooling device is installed so as to facilitate temperature control, a monomer mixture consisting of 82.5 g of ethylhexyl acrylate, and 17.5 g of hydroxyethyl acrylate (HEA) was introduced. Subsequently, based on 100 g of the monomer mixture, 200 g of ethylacetate (EAc) was introduced as a solvent, and while nitrogen was introduced so as to remove oxygen in the reactor, the mixture was sufficiently mixed at 30° C. for more than 60 minutes. Thereafter, a temperature was raised to and maintained at 65° C., 0.1 g of an initiator of azobisisobutylonitrile (V-60™ manufactured from Wako Pure Chemical Industries) was introduced portionwise to initiate a reaction, and then, polymerization was progressed for 6 hours to prepare a primary reaction product.

(18) To the primary reaction product, 20 g of methacryloyl isocyanate (MOI) (85.5 mol %, based on HEA in the primary reaction product) and 0.08 g of a catalyst (dibutyltin dilaurate, DBTDL) were added, and reacted at 40° C. for 24 hours to introduce UV curable groups at the side chain of the polymer in the primary reaction product, thus preparing (meth)acrylate-based binder resin (b-1).

(19) 100 g of the (meth)acrylate-based binder resin (b-1) was mixed with 2.0 g of TDI-based isocyanate curing agent, 1.2 g of isopropyl thioxanthone (ITX) as a photoinitiator, and 6.0 g of ethyl-p-dimethyl amino benzoate as a tertiary amine-based compound to prepare a composition for forming an adhesive layer.

Comparative Preparation Example 2

(20) Into a reactor in which nitrogen gas is refluxed and a cooling device is installed so as to facilitate temperature control, a monomer mixture consisting of 62.5 g of ethylhexyl acrylate, 20 g of silicone (meth)acrylate (Silaplane™ FM-0721 manufactured from JNC Corporation) and 17.5 g of hydroxyethyl acrylate (HEA) was introduced. Subsequently, based on 100 g of the monomer mixture, 200 g of ethylacetate (EAc) was introduced as a solvent, and while nitrogen was introduced so as to remove oxygen in the reactor, the mixture was sufficiently mixed at 30° C. for more than 60 minutes. Thereafter, a temperature was raised to and maintained at 65° C., 0.1 g of an initiator of azobisisobutylonitrile (V-60™ manufactured from Wako Pure Chemical Industries) was introduced portionwise to initiate a reaction, and then, polymerization was progressed for 6 hours to prepare a primary reaction product.

(21) To the primary reaction product, 10 g of methacryloyl isocyanate (MOI) (42.7 mol %, based on HEA in the primary reaction product) and 0.045 g of a catalyst (dibutyltin dilaurate, DBTDL) were added, and reacted at 40° C. for 24 hours to introduce UV curable groups at the side chain of the polymer in the primary reaction product, thus preparing binder resin (b-2).

(22) 100 g of the binder resin (b-2) was mixed with 2.0 g of toluene diisocyanate (TDI) as a multifunctional crosslinking agent, 1.2 g of isopropyl thioxanthone (ITX) as a photoinitiator, and 6.0 g of ethyl-p-dimethyl amino benzoate as a tertiary amine-based compound to prepare an adhesive composition.

Comparative Preparation Example 3

(23) Into a reactor in which nitrogen gas is refluxed and a cooling device is installed so as to facilitate temperature control, a monomer mixture consisting of 62.5 g of ethylhexyl acrylate, 20 g of silicone (meth)acrylate and 17.5 g of hydroxyethyl acrylate (HEA) was introduced. Subsequently, based on 100 g of the monomer mixture, 200 g of ethylacetate (EAc) was introduced as a solvent, and while nitrogen was introduced so as to remove oxygen in the reactor, the mixture was sufficiently mixed at 30° C. for more than 60 minutes. Thereafter, a temperature was raised to and maintained at 65° C., 0.1 g of an initiator of azobisisobutylonitrile (V-60™ manufactured from Wako Pure Chemical Industries) was introduced portionwise to initiate a reaction, and then, polymerization was progressed for 6 hours to prepare a primary reaction product.

(24) To the primary reaction product, 22.9 g of methacryloyl isocyanate (MOI) (97 mol %, based on HEA in the primary reaction product) and 0.091 g of a catalyst (dibutyltin dilaurate, DBTDL) were added, and reacted at 40° C. for 24 hours to introduce UV curable groups at the side chain of the polymer in the primary reaction product, thus preparing binder resin (b-3).

(25) 100 g of the binder resin (b-3) was mixed with 2.0 g of toluene diisocyanate (TDI) as a multifunctional crosslinking agent, 1.2 g of isopropyl thioxanthone (ITX) as a photoinitiator, and 6.0 g of ethyl-p-dimethyl amino benzoate as a tertiary amine-based compound to prepare an adhesive composition.

Comparative Preparation Example 4

(26) An adhesive composition was prepared by the same method as Preparation Example 1, except that the binder resin (b-1) of Comparative Preparation Example 1 was used as binder resin when preparing an adhesive composition, and silicone (meth)acrylate was further added.

(27) Specifically, 80 g of the binder resin (b-1) prepared in Comparative Preparation Example 1 was mixed with 20 g of silicone (meth)acrylate, 2.0 g of toluene diisocyanate (TDI) as a multifunctional crosslinking agent, 1.2 g of isopropyl thioxanthone (ITX) as a photoinitiator, and 6.0 g of ethyl-p-dimethyl amino benzoate as an amine-based compound to prepare an adhesive composition.

(28) The content of each repeat unit in the binder resin prepared in Preparation Examples 1-3 and Comparative Preparation Examples 1-3, and the properties (Mw and Tg) were analyzed and measured, and the results were shown in the following Table 1.

(29) In the following Table 1, the content of each repeat unit in the binder resin was calculated through NMR analysis. And, Mw is weight average molecular weight converted in terms of polystyrene, measured using GPC, and Tg is a glass transition temperature measured with DSC.

(30) TABLE-US-00001 TABLE 1 Content of repeat unit in the binder resin Silicone Photoreactive (meth)acrylate- HEA- EHA and/or BA- functional group- derived first derived second derived third introduced second repeat units repeat units repeat units repeat units Kind of (wt %, based (wt %, based (wt %, based (wt %, based on total binder on total weight on total weight on total weight weight of HEA-derived Mw Tg resin of binder resin) of binder resin) of binder resin) second repeat unit) (g/mol) (° C.) Preparation a-1 20 20.5 59.5 95 1,100,000 −43.6 Example 1 Preparation a-2 30 20.5 49.5 95 1,070,000 −38.5 Example 2 Preparation a-3 20 20.5 59.5 95 1,200,000 −34.7 Example 3 Comparative b-1 — 20.5 79.5 95 1,200,000 −48.4 Preparation Example 1 Comparative b-2 20 20.5 59.5 15 1,100,000 −49.9 Preparation Example 2 Comparative b-3 20 20.5 59.5 99.9 1,100,000 −41.6 Preparation Example 3
<Preparation of an Adhesive Sheet for Temporary Fixing>

Example 1

(31) The adhesive composition of Preparation Example 1 was coated on a release-treated polyethylene terephthate film (thickness 38 μm, glass transition temperature: 120° C.), and then, dried at 110° C. for 3 minutes to form an adhesive layer of about 30 μm thickness. The formed adhesive layer was laminated to a polyimide base film of 50 μm thickness, and then, aged to obtain an adhesive sheet for temporary fixing.

Examples 2 to 3 and Comparative Examples 1 to 4

(32) Adhesive sheets for temporary fixing were prepared by the same method as Example 1, except that the components and amounts of the following Table 2 were used.

(33) TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 1 Example 2 Example 3 Example 4 Base film polyimide polyimide polyimide polyimide polyimide polyimide polyimide Adhesive Preparation Preparation Preparation Comparative Comparative Comparative Comparative composition Example 1 Example 2 Example 3 Preparation Preparation Preparation Preparation for forming Example 1 Example 2 Example 3 Example 4 adhesive layer

Experimental Example: Evaluation of Adhesive Force and Peel Strength

(34) For the adhesive sheets for temporary fixing prepared according to Examples and Comparative Examples, adhesive force and peel strength according to photocuring were evaluated as follows, and the results were shown in the following Table 3.

(35) Each adhesive sheet for temporary fixing prepared in Examples and Comparative Examples was cut to a width of 25 mm, and then, attached to a silicon wafer using a 2 kg roller, thus preparing a sample A (before heat treatment).

(36) Next, the adhesive sheet for temporary fixing, attached to a silicon wafer, was left in an oven of 250° C. for 10 minutes to prepare a heat-treated sample B (after heat treatment).

(37) To the above prepared non-heat-treated sample A and heat-treated sample B, UV (using a mercuary lamp having a complex wavelength of 200 nm to 500 nm region) was irradiated from the base film at the light quantity of 1000 mJ/cm.sup.2, and adhesive force was measured.

(38) The adhesive force (gf/25 mm) was measured at a speed of 300 mm/min and an angle of 180 degree using a Texture Analyzer of Stable Micro Systems, and the results were shown in the following Table 3.

(39) And, from the measured adhesive force, a rate of change in the adhesive force of the adhesive layer was calculated according to the following Mathematical Formula 1.
Rate of change in the adhesive force of the adhesive layer (%)=A2×100/A1   [Mathematical Formula 1]

(40) (in the Mathematical Formula 1, A1 is the adhesive force of the adhesive layer after heat treating at 250° C. for 10 minutes,

(41) A2 is the adhesive force of the adhesive layer, after irradiating UV of complex wavelength of 200 nm to 500 nm region to the heat-treated adhesive layer at the light quantity of 100 mJ/cm.sup.2 to 2000 mJ/cm.sup.2)

(42) And, foaming and lifting in the heat-treated sample B were observed with the unaided eyes. The results were respectively shown in FIGS. 3 and 4. FIG. 3 and FIG. 4 are photographs observing the appearance after heat treatment of the adhesive sheets for temporary fixing of Example 1 and Comparative Example 1, respectively.

(43) TABLE-US-00003 TABLE 3 Non-heat-treated sample A Heat-treated sample B Evaluation of adhesive Evaluation of adhesive Rate Heat-treated sample B force(gf/25 mm) force(gf/25 mm) of change Evaluation of Before UV After UV Before UV After UV in adhesive appearance property irradiation irradiation irradiation irradiation force(%) (foaming and lifting) Example 1 38 6 135 33 24.4 Not generated Example 2 31 5  98 25 25.5 Not generated Example 3 46 7 152 38 25.0 Not generated Comparative 43 11 347 193 55.6 Generated Example 1 Comparative 67 43 512 381 74.4 Generated Example 2 Comparative transcribed 15 transcribed Transcribed Generated Example 3 Comparative ND ND ND ND ND ND Example 4 In the Table 3, ND means non-measurable.

(44) As confirmed from the experimental results of the heat-treated sample B of the Table 3, the adhesive sheets for temporary fixing of Examples 1 to 3 prepared according to the present invention can be removed without adhesive residue when peeled from a silicon wafer, because adhesive force after high temperature heat treatment was significantly lowered. And, the adhesive sheets for temporary fixing of Examples 1 to 3 did not exhibit deterioration of appearance property such as foaming or lifting even after heat treatment at a high temperature of 250° C.

(45) To the contrary, the adhesive sheet for temporary fixing of Comparative Example 1, which was prepared using (meth)acrylate resin including only photoreactive functional groups without silicon-based functional groups as binder, exhibited high adhesive force even after heat treatment, and thus, adhesive residue was generated when peeled from a silicon wafer, and foaming and lifting were generated on the surface after heat treatment.

(46) And, the adhesive sheet for temporary fixing of Comparative Example 2, wherein (meth)acrylate resin including photoreactive functional groups together with silicon functional groups is used as binder, but the content of the second repeat units in which the photoreactive functional groups are introduced is less than 20 wt % based on the total weight of the second repeat units in the (meth)acrylate resin, exhibited high adhesive force even after heat treatment, and thus, adhesive residue was generated when peeled from a silicon wafer, and like Comparative Example 1, foaming and lifting were generated on the surface after heat treatment.

(47) And, in the case of the adhesive sheet for temporary fixing of Comparative Example 3, wherein the content of the second repeat units in which the photoreactive functional groups are introduced is greater than 95 wt % based on the total weight of the second repeat units in the (meth)acrylate resin, transcription was generated after heat treatment, and like Comparative Examples 1 and 2, foaming and lifting were generated on the surface after heat treatment.

(48) Meanwhile, in the case of the adhesive of Comparative Example 4, which was prepared by simply mixing (meth)acrylate binder resin including only photoreactive functional groups without silicon-based functional groups with silicone (meth)acrylate, due to low compatibility of (meth)acrylate binder resin and silicone (meth)acrylate, phase separation and gelation were progressed during stirring, and thus, could not be prepared into an adhesive sheet.