KR20000011377A - Uv curable pressure sensitive adhesive - Google Patents

Abstract

PURPOSE: A UV curable decompressive adhesive composition is provided, which is a liquid in atmospheric temperature, and has good peel strength at a temperature between 85 to -40°C. CONSTITUTION: The UV curable adhesive composition comprises polyacrylate having photosensitive pendent functional groups in a range of 60-90 weight parts; vinyl ether in a range of 10-40 weight parts; and an onium salt initiator in a range of 1-4 weight parts based on the weight of the polyacrylate and vinyl ether. The polyacrylate is preferably selected from the group consisting of ACRONAL 3429 and ACRONAL 3458 (BASF corporation). The vinyl ether has low viscosity and Tg between -50 to +10°C. The vinyl ether is preferably selected from the group consisting of butyl vinyl ether, ethylhexyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, cyclohexyl vinyl ether, isobutyl vinyl ether, and hydroxybutyl vinyl ether. The initiator is preferably sulfonium hexafluoroantimonate of the formula 1.

Description

ＵＶ Curable Pressure Sensitive Adhesive {UV CURABLE PRESSURE SENSITIVE ADHESIVE}

The present invention relates to a UV curable pressure sensitive adhesive.

Pressure sensitive adhesives are used in a variety of applications because of their ease of handling and immediate adhesion. The adhesive materials are suitable for use at either high or low temperatures, but it is not yet possible to make one material available for both high and low temperature environments. For example, the pressure sensitive adhesive may be provided as an adhesive for use in the hood of an automobile. However, materials that can provide sufficiently strong bonding at elevated temperatures can also break or lose adhesion at low temperatures, and adhesives with strength and flexibility at low temperatures can also break or weaken at high temperatures.

The present invention is a UV curable adhesive composition comprising a polyacrylate, vinyl ether and onium salt photoinitiator containing photosensitive pendant functional groups. The composition is a pressure sensitive adhesive that is liquid at environmental temperatures and has good peel strength in the temperature range of 85 ° C. to −40 ° C. and is cured by UV irradiation.

Polyacrylates are chains of saturated polymers prepared from acrylate monomers, which also contain photosensitive pendant functional groups. This photosensitive pendant functional group is attached to a polyacrylate having a binding force of sufficient length to promote intramolecular bonding. The polymer usually has an average molecular weight of 2,000 to 10,000. Preferred polyacrylates are those sold under the trade names ACRONAL 3429 and ACRONAL 3458 by BASF. The polyacrylate will be present in 60 to 90 parts by weight in 100 parts by weight of the composition.

Preferred vinyl esters have low viscosity and have Tg values of -50 ° C to + 10 ° C. Particularly preferred vinyl esters are C ₄ to C ₁₀ ethers. This ether may also contain hydroxyl groups. Examples of vinyl ethers are butyl vinyl ether, ethylhexyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, cyclohexyl vinyl ether, isobutyl vinyl ether and hydroxy-butyl vinyl ether. More preferred vinyl ethers are butyl vinyl ethers. Vinyl ether will be present in 10 to 40 parts by weight per 100 parts by weight of the composition.

Preferred onium salt photoinitiators are known to initiate cationic curing with diaryliodonium, triarylsulfonium, and ferrocenium salts. Such salts are disclosed in detail in US Pat. Nos. 4,069,055 and 4,058,401 to Crivello. Preferred onium salts are sulfonium hexafluoroantimonates purchased from Union Carbide having the structure:

These initiators will be present in an amount effective to initiate the curing process but will typically be present in an amount of 0.1 to 10 parts by weight, preferably 1 to 4 parts by weight, per 100 parts by weight of polyacrylate and vinyl ether.

Example

Samples of various adhesive compositions in accordance with the present disclosure were prepared and compared with conventional UV curable adhesives for peel strength in the following manner. Each composition was applied to a Mylar substrate and irradiated with UV light for 3 seconds with a D-shaped bulb from a 300 watt Fusion UV system. The substrate was 6 cm away from the light source. The cured coating films were then joined in pairs and applied together by a five pound rubber roller to bond together. This laminate was cut into 2.54 cm (1 inch) wide and 15.24 cm (6 inch) lengths for 180 ° peel test. The peel test was performed on an Instron Tensile Unit.

The composition of the sample and the results of the peel strength test are reported in the following table. The composition of the sample is provided in parts by weight. Irgacure is a basic photoinitiator purchased from Ciba Geigy. Peel strength values are reported in n / m. Sample Compositions A and B are samples of the present invention and Compositions C and D are standard formulations of UV curable adhesives.

Composition (parts by weight) A B C D Acronal 3429 75 75 75 75 Butyl vinyl ether 25 Ethylhexyl vinyl ether 25 Ethylhexyl acrylate 25 Tetrahydrofurfuryl acrylate 25 Sulfonium hexafluoroantimonate One One Irgacure 1173 One One Peel strength value of N / meter -40 ℃ 400 550 400 350 22 ℃ 800 850 250 300 85 ℃ 530 450 50 70

The data show that sample compositions A and B have superior peel strength values than those of other standard formulations.

Claims (5)

(Iii) polyacrylates having from 60 to 90 parts by weight of photosensitive pendant functional groups; (Ii) 10 to 40 parts by weight of vinyl ether; And (Iii) 1 to 4 parts by weight of the onium salt photoinitiator based on the weight of the polyacrylate and vinyl ether UV curable adhesive composition comprising a. The method of claim 1, Wherein said polyacrylate is selected from the group consisting of polyacrylates sold under the trade names ACRONAL 3429 and ACRONAL 3458 of BASF Corporation. The method of claim 1, Wherein the vinyl ether has a low viscosity and a Tg value of -50 ° C to + 10 ° C. The method of claim 1, Wherein said vinyl ether is selected from the group consisting of butyl vinyl ether, ethylhexyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, cyclohexyl vinyl ether, isobutyl vinyl ether, and hydroxybutyl vinyl ether. The method of claim 1, UV curable adhesive composition wherein the photoinitiator is sulfonium hexafluoroantimonate.