Triply curable optically clear adhesive

Abstract

The present invention provides an adhesive composition, which can be cured through three ways: UV-radiation curing, thermal-radiation curing and moisture-curing. The adhesive composition comprises a) an oligomer having an isocyanate group and a (meth)acryloxy group; b) a (meth)acrylic monomer and/or oligomer not having an isocyanate group; c) a photoinitiator; and d) a peroxide.

Claims

1. An adhesive composition, comprising: a) an oligomer having an isocyanate group and a (meth)acryloxy group; b) a (meth)acrylic monomer and/or oligomer not having an isocyanate group; c) a photoinitiator; and d) a peroxide.

2. The adhesive composition according to claim 1, wherein said composition further comprises an organometal catalyst.

3. The adhesive composition according to claim 2, wherein said organometal catalyst is selected from stannous octoate, dibutyltin dilaurate and dibutyltin diacetate.

4. The adhesive composition according to claim 1, wherein said component a) is an aliphatic urethane having an isocyanate group and a (meth)acryloxy group.

5. The adhesive composition according to claim 1, wherein said component b) is an aliphatic (meth)acrylate monomer.

6. The adhesive composition according to claim 1, wherein said photoinitiator is selected from hydroxyketones initiators and acyl phosphine peroxides initiators.

7. The adhesive composition according to claim 1, wherein said peroxide is selected from peroxyesters and alkyl peroxides.

8. The adhesive composition according to claim 1, comprising 20 wt. % to 80 wt. % of an oligomer having an isocyanate group and a (meth)acryloxy group; 20 wt. % to 80 wt. % of a (meth)acrylic monomer and/or oligomer not having an isocyanate group; 0.1 wt. % to 3.0 wt. % of a photoinitiator; 0 wt. % to 3.0 wt. % of an organometal catalyst; and 0.1 wt. % to 3.0 wt. % of a peroxide; the total weight percents of the components in the adhesive composition add up to 100 wt. %.

9. A method for bonding and sealing using the adhesive composition according to claim 1, said method comprises: irradiating the region to be bonded or sealed that is coated with the adhesive composition of the invention with UV-light; placing the parts to be bonded or sealed under a heat-curing condition; and/or placing the parts to be bonded or sealed under a moisture-curing condition.

10. A liquid crystal display product assembled with the adhesive composition according to claim 1.

Description

EXAMPLES

(1) The examples as well as data of effects shown as below are used to detailedly describe the advantages of the present invention and how to carry out the present invention. However, the protection scope of the present invention is not limited to these examples.

(2) Materials for Experiments

(3) Desmolux D 100 (Bayer, AG) CN9021 (Sartomer Chemical Ltd.) Desmolux VP LS 2396 (Bayer, AG)
Test Methods

(4) To testify the excellent performances of the adhesive composition of the invention, properties of UV-curing, moisture-curing, thermal-curing, adhesion strength and transmittance were tested.

(5) UV-Curing Test

(6) The UV-curing test was carried out at room temperature at a wavelength of about 200 nm to about 400 nm using a UV light source (Loctite UVALOC 1000, Henkel AG) which has a radiation energy of about 3000 mJ/cm.sup.2. For example, irradiation to each adhesive composition was carried out about 30 seconds or more at a radiation power of about 100 mW/cm.sup.2.

(7) Moisture-Curing Test at Room Temperature

(8) After bonded with the adhesive composition, the samples were put into a room with absolutely no light at a constant temperature (23±2° C.) and constant moisture (50±10% RH). To ensure no light, the samples may be covered by aluminium foil. According to predetermined target time, the result of moisture curing was checked.

(9) Thermal-Curing Test

(10) The thermal curing test was carried out for the adhesive composition between glass and polycarbonate (PC) in a temperature-adjustable oven with a highest temperature of not lower than 200° C. under no light condition. The specific curing temperature and time depend on the specific formulation of the adhesive composition.

(11) Test of Adhesion Strength

(12) The adhesion strength is used to characterize the bonding strength between two substrates brought by fully cured adhesive composition. Normally the thickness of curing layer was around 100 μm according to requirements. The substrates were chosen from glass plates, PMMA plates and polyester plates. The equipment for test was Universal tensile test machine (Instron 5569, Instron Inc.). During this test, the two sample plates bonded together were pulled apart in an opposite direction. The adhesion strength (MPa) was obtained by dividing the force value tested by the bonded area.

(13) Test of Transmittance

(14) The transmittance of the cured adhesive composition in visible light region was tested by a UV and visible light spectrophotometer. The curing thickness of the adhesive composition was controlled by two glass layer to around 100 μm. Test method refers to ASTM D1005-2007. According to the test method, the adhesive composition between two glass plates was irradiated for 30s by a UV light with a radiation power of 100mW/cm.sup.2, and the transmittance of the cured adhesive composition was tested.

(15) Preparation of the Adhesive Composition

Example 1

(16) At room temperature, 50.75 parts by weight of Desmolux D 100, 45 parts by weight of isobornyl acrylate and 2 parts by weight of 2-hydroxyl-2-methyl-1-phenyl-1-acetone were weighted separately into a stirred tank to conduct stirring, and the stirring rate was set at about 60 rpm and the stirring time was about 60 min. Subsequently, 1 parts by weight of (2,4,6-trimethylbenzoyl)-diphenyl-phosphine oxide, 0.25 parts by weight of dibutyltin dilaurate and 2 parts by weight of 1,1-ditertbutylperoxy-3,3,5-trimethyl-cyclohexane were weighted separately into the stirred tank, and the stirring rate was set at about 100 rpm and the stirring was further carried out about 60 min. After all components were mixed evenly, the mixture was filtered. During the whole process of feeding and mixing, keep away from light and keep a constant temperature.

(17) The formulation of the adhesive composition according to Example 1 is as below:

(18) TABLE-US-00001 Components Parts by weight Desmolux D 100: aliphatic urethane (meth)acrylate 50.75 oligomer having an isocyanate group isobornyl acrylate 45 2-hydroxyl-2-methyl-1-phenyl-1-acetone 2 (2,4,6-trimethylbenzoyl)-diphenyl-phosphine oxide 1 dibutyltin dilaurate 0.25 1,1-ditertbutylperoxy-3,3,5-trimethylcyclohexane 2

(19) The inventive adhesive compositions of Examples 2 to 5 and the adhesive compositions of Comparative Examples 1 to 4 were prepared in the same manner as in Example 1 except that the formulation of the adhesive composition was changed.

(20) The formulations of Example 1 and Comparative Examples 1 to 4 as well as their performance data of UV curing, moisture curing and thermal curing are shown in Table 1.

(21) TABLE-US-00002 TABLE 1 Contents of components in different Examples (wt %) Component Comparative Comparative Comparative Comparative type Component name Example 1 Example 1 Example 2 Example 3 Example 4 (Meth)acrylate Desmolux D 100: aliphatic urethane (meth)acrylate 50.75 50.75 50.75 75.75 / oligomer oligomer having an isocyanate group (Meth)acrylate CN9021: aliphatic urethane (meth)acrylate / / / / 75 oligomer (Meth)acrylate isobornyl acrylate 45 40 46 24   20 monomer (Meth)acrylate hydroxypropyl (meth)acrylate / 6 / / / monomer Photoinitiator 2-hydroxyl-2-methyl-1-phenyl-1-acetone 2 2 / /  3 Photoinitiator (2,4,6-trimethylbenzoyl)-diphenyl-phosphine oxide 1 1 / /  2 Organometal dibutyltin dilaurate 0.25 0.25 0.25  0.25 / catalyst Peroxide 1,1-ditertbutylperoxy-3,3,5-trimethylcyclohexane 2 / 2 / / Peroxide tert-butyl peroxybenzoate / / 1 / / Performance UV-curing (room temperature; glass to PC), Cured Cured Not cured Not cured Cured test 1 30 s@UVA (100 mW) within 30 s within 30 s within 30 s Performance Moisture curing (room temperature and keep away Cured Cured Cured Cured Not cured test 2 from light, glass to PC), 23° C., 60% RH within 24 hours within 24 hours within 24 hours within 24 hours Performance Thermal curing (keep away from light, glass to PC), Cured Not cured Cured Not cured Not cured test 3 80° C. oven after 1 hour after 1 hour

(22) Table 1 shows that the adhesive compositions of the invention can be cured via three ways, and have excellent curing properties in each way of UV-curing, moisture-curing and thermal-curing.

(23) Table 2 shows five Examples of the inventive adhesive composition. All of them can be cured via three ways. Through adjusting proportions of each component, different thermal-curing effects and adhesion strengths can be achieved after curing.

(24) TABLE-US-00003 TABLE 2 Component Contents of components in different Examples (wt %) type Component name Example 1 Example 2 Example 3 Example 4 Example 5 (Meth)acrylate Desmolux D 100: aliphatic urethane (meth)acrylate 50.75 50.75 50.75 15.75 / oligomer oligomer having an isocyanate group (Meth)acrylate Desmolux VP LS 2396: aliphatic urethane (meth)acrylate / / / 35 50.75 oligomer oligomer having an isocyanate group (Meth)acrylate isobornyl acrylate 45.5 44.5 22 22 22 monomer (Meth)acrylate hydroxypropyl (meth)acrylate / / 22 22 22 monomer Photoinitiator 2-hydroxyl-2-methyl-1-phenyl-1-acetone 2 2 2 2 2 Photoinitiator (2,4,6-trimethylbenzoyl)-diphenyl-phosphine oxide 1 1 1 1 1 Organometal dibutyltin dilaurate 0.25 0.25 0.25 0.25 0.25 catalyst Peroxide 1,1-ditertbutylperoxy-3,3,5-trimethylcyclohexane 1.5 1.5 2 2 2 Peroxide tert-butyl peroxybenzoate / 1 1 1 1 Performance UV curing (room temperature, glass to PC), Cured Cured Cured Cured Cured test 1 30 s@UA (100 mW/cm.sup.2) within 30 s within 30 s within 30 s within 30 s within 30 s Performance Moisture curing (room temperature and keep away Cured Cured Cured Cured Cured test 2 from light, glass to PC), 23° C., 60% RH within 24 h within 24 h within 24 h within 24 h within 24 h Performance Thermal curing (keep away from light, glass to PC), oven 2 hr 1 hr 2 hr 2 hr 2 hr test 3 (temperature-adjustable and the highest temperature being @80° C. @80° C. @70° C. @70° C. @70° C. not lower than 200° C.) Performance Adhesion strength (glass plate to glass plate, curing >0.4 Mpa >0.4 Mpa >0.6. Mpa >0.6 Mpa >0.6 Mpa test 4 conditions: UVA with power 100 mW/cm.sup.2, 30 s) Performance Transmittance (glass plate to glass plate, curing condition: >92% >92% >92% 92% 92% test 5 UVA with power 100 mW/cm.sup.2, 30 s)

(25) The present invention is illustrated in details in the embodiments; however, it is apparent for those skilled in the art to modify and change the embodiments without deviating from the spirit of the invention. All the modifications and changes should fall in the scope of the appended claims of the present application.