KR20060130397A - UV curable pressure-sensitive adhesive composition containing silicone acrylate and article cured photocured with the composition - Google Patents

Abstract

The present invention relates to a UV-curable pressure-sensitive adhesive composition and an article photocured and bonded with the composition, 100 parts by weight of the acrylic monomer, 0.1-10 parts by weight of the silicone acrylate based on 100 parts by weight of the acrylic monomer and may participate in the polymerization. There is provided an ultraviolet curable pressure-sensitive adhesive composition comprising 0.1-10 parts by weight of a photopolymerization initiator having a functional group, and an article photocured and bonded with the ultraviolet curable pressure-sensitive adhesive composition.

The present invention is polymerized to include a silicone acrylate with a photoinitiator in the acrylic monomer to compensate for the disadvantages of the acrylic pressure-sensitive adhesive so that no residue remains after curing, and the advantages of the acrylic pressure-sensitive adhesive and low price and the ability to change the characteristics according to the functional group and Easily polymerized at room temperature and the advantages of the silicone pressure-sensitive adhesive to have a weather resistance, heat resistance, excellent peel force. In addition, it has the advantage of having an environmentally friendly and fast production speed using ultraviolet curing.

Description

UV-curable pressure sensitive adhesives containg silicone acrylate and the article bonded by radiation curing with the composition

The present invention relates to an ultraviolet curable pressure-sensitive adhesive composition containing a silicone acrylate and an article photocured and bonded with the composition. More specifically, ultraviolet curing is possible by polymerizing a silicone acrylate component and a photoinitiator component to an acrylic monomer. And a peelable and reactivateable transparent UV curable pressure-sensitive adhesive composition and an article photocured to the composition.

UV-curable pressure-sensitive adhesive is an active and permanent adhesive material by applying at room temperature and crosslinking using ultraviolet light, and adheres strongly to various dissimilar surfaces when light pressure is applied such as pressing with a finger. For this property, the adhesive should have good initial adhesion, cohesion and cohesion and a good balance between them, and should not cause surface damage and contamination of the adhesive when peeled for removal after prolonged adhesion. have.

In addition, the pressure-sensitive adhesive should exhibit a low level of acceptable increase in adhesion over time even at high temperatures, so that the peeling should be possible even after long-term stay.

In addition, the pressure-sensitive adhesive should be able to be used for outdoor use because it exhibits high resistance to water and ultraviolet rays.

Another requirement is to have sufficient cohesion and tensile strength so that the adhesive can be repeatedly attached to the substrate even after one or several peels. In general, the adhesive force increases as the thickness of the pressure-sensitive adhesive increases, so it has to have sufficient cohesive strength to limit the room temperature fluidity of the pressure-sensitive adhesive on the surface.

It is not easy to combine the above desirable properties. Peelable pressure-sensitive adhesives disclosed at the state of the art do not conform to a desirable extent to the properties as described above.

U.S. Patent No. 4,710,536 discloses a peelable pressure sensitive adhesive whose precursor is based on alkyl acrylates. Further contains hydrophobic silica in a weight of 2-15 phr as filler. However, the pressure-sensitive adhesive disclosed in the patent can only be peeled off at an initial stage but not within a few days. In addition, the pressure-sensitive adhesive disclosed in the patent is relatively inferior in reactivation characteristics.

The precursor of the pressure sensitive adhesive disclosed in German Patent No. 42 14 507 is based primarily on alkyl acrylates. This precursor further contains a filler component of natural polysaccharide. But. The adhesive material disclosed in this patent is white-opaque and therefore undesirable from an aesthetic point of view.

European Patent No. 684,295 or Japanese Patent No. Hei 6-322355 simply by plasticizing the polyol in the acrylic pressure-sensitive adhesive to promote adhesion to increase the shear resistance of the adhesive.

Many examples of acrylic adhesives with this patent are described in Pressure Sensitive Adhesives Technology, 1 ^st Edition, 1996, Istvan Benedek and Luc J. Heymans.

As a result of combining all the above examples, the acrylic pressure-sensitive adhesive generally has two disadvantages. The first is very good adhesion to high surface energy materials but relatively poor adhesion to low surface energy materials. This is because acrylic pressure sensitive adhesives generally have high surface energy and high polarity. The second disadvantage is that the adhesive force is too high and the heat resistance is poor due to the high shear resistance.

In addition, the currently developed method of curing the pressure-sensitive adhesive is prepared by applying the adhesive solution to the appropriate backing plate and removing the solvent by a volatile removal process, but there is a problem due to the increased cost and production speed of the solvent.

Therefore, in order to compensate for the disadvantages of the acrylate pressure-sensitive adhesive as described above and to reduce the additional cost required for pressure-sensitive adhesive production, it is necessary to increase productivity through curing with ultraviolet rays.

Accordingly, the present invention polymerizes the silicone acrylate and photoinitiator to the acrylic monomer to take advantage of the acrylic and silicone-based to provide a UV-curable pressure-sensitive adhesive composition excellent in easy modification and excellent peelability and stability according to the introduction of functional groups at room temperature, atmospheric pressure. The purpose is to.

In addition, an object of the present invention is to provide an article that is photocured and bonded with the UV-curable pressure-sensitive adhesive composition.

According to the first aspect of the present invention, an ultraviolet ray including 100 parts by weight of an acrylic monomer, 0.1-10 parts by weight of a silicone acrylate based on 100 parts by weight of the acrylic monomer, and 0.1-10 parts by weight of a photopolymerization initiator having a functional group capable of participating in polymerization. A curable pressure-sensitive adhesive composition is provided.

According to the second aspect of the present invention, there is provided an article that is photocured and bonded with the ultraviolet curable pressure-sensitive adhesive composition.

Hereinafter, the present invention will be described in more detail.

The acrylic monomer, which is a main component of the pressure-sensitive adhesive used in the present invention, becomes a polyacrylate during polymerization, and its advantage is an aliphatic polymer having no double bond in the molecule, and excellent resistance to oxidation in terms of its inherent properties.

In addition, it is easy to modify due to the change of the composition of the polymer or the introduction of the functional group according to the required physical properties, and in terms of productivity, the emulsion or solution polymerization can be made relatively easily at room temperature and atmospheric pressure.

Disadvantages are very good adhesion to high surface energy materials but relatively poor adhesion to low surface energy materials. This is because acrylic adhesives generally have high surface energy and high polarity.

The second disadvantage is that the adhesive force is too high due to the high shear resistance.

In order to overcome these shortcomings and to create a pressure-sensitive adhesive having excellent peelability, silicon acrylates were used to introduce advantages of silicone resins.

The silicone acrylate group was introduced into the silicone pressure-sensitive adhesive resin. Since these resins have low surface energy and excellent viscosity retention, they exhibit excellent adhesion even upon reattachment without showing surface damage or contamination of the adherend upon removal, and thus have been widely used as an easy peelable pressure-sensitive adhesive. .

The main component of the present invention is an acrylic monomer that uses 4-17 carbon atom alkyl acrylate and methacryl as an acrylic ester capable of synthesizing a soft and sticky polymer having a low glass transition temperature so as to be -30 ° C. or less at room temperature for excellent adhesion. It was. The acrylic monomers include methyl methacrylate, styrene, 2-ethylhexyl methacrylate, lauryl methacrylate, methyl acrylate, n-butyl acrylate, 2-ethylhexyl methacrylate, and ethyl acryl having an acryl group. At least one is selected from the group consisting of rates.

The main monomer of the acrylic monomer which is the main component of the present invention should be about 50-90 parts by weight of the acrylic monomer. When the content of the main monomer is too high, unreacted materials that do not participate in the polymerization reaction remain in the pressure-sensitive adhesive, leaving a residue upon peeling. The modified monomer should be about 10-14 parts by weight, and the functional group should not exceed 2-20 parts by weight. In the case of a large number of functional groups, the adhesive force increases rapidly, making it difficult to remove the adhesive from the adherend and leaving a residue after peeling.

Silicone acrylate should not exceed about 0.1-10 parts by weight. As the content of the silicone acrylate increases, the molecular weight of the pressure-sensitive adhesive decreases and the viscosity becomes too low.

The photoinitiator should be present in an amount of 0.1-10 parts by weight. As the content of the photoinitiator increases, gelation of the polymer occurs in the polymerization process.

Based on the above composition, 2-ethylhexyl methacrylate, lauryl methacrylate, methyl acrylate, n-butyl acrylate, 2-ethylhexyl methacrylate having soft properties as main monomers in the polymerization composition table of Table 1 Etc. may be used, and vinyl acetate, methyl methacrylate or styrene having hard properties may be used as the non-functionally modified monomer.

As the functional monomer group, acrylic acid, methacrylic acid or maleic acid, acrylamide, glycidal methacrylate, or the like may be used.

As the silicone acrylate used in the present invention, product names FM 0711, 0721, 0725, 7711, 7721, 7725 and TM 0701, TM-0701T, and Gold Schmidt's AF-PDMS may be used. The silicone acrylate group may use monofunctional silicone acrylate, but polyfunctional silicone acrylate and silicone acrylate having a molecular weight of 500,000 or less according to each functional group may also be used.

The silicone acrylate used in the present invention has a functional group of carbon double bonds of acrylic in the molecular structure, so that double bonds open during polymerization to bond with the main chain to form an adhesive.

The photoinitiator is at least one selected from the group consisting of benzophenone or benzophenone derivatives and thioxanthone or thioxanthone derivatives. Preference is given to 4-benzophenone diethyleneglucol acrylate. The acrylate group in the molecular group of the photoinitiator is capable of binding to the polymer chain during polymerization, and the benzophenone group is a group that allows crosslinking through hydrogen substitution reaction to occur during UV curing.

The composition of the present invention is polymerizable through free radical polymerization using a thermal initiator in solvent type polymerization. Although ethyl acetate was used as a solvent, cyclohexane, toluene, n-heptane, etc. can also be used. The photocurable pressure-sensitive adhesive composition has a molecular weight of 1,000,000 or less upon polymerization.

The present invention will be described in more detail with reference to the following examples.

<Example>

The form used for the physical property evaluation in the present invention used a tape form by applying an adhesive to one side of the support of the polyethylene terephthalate film with an adhesive tape and UV-cured.

And the physical properties were measured according to the following measurement method is shown in Table 2, 3, 4, 5.

[Measurement Items and Methods]

1. 180 ° Peel Adhesion (FINAT FTM1): Based on the pressure-sensitive tape test criteria, the width should be 25.4mm, the minimum length should be 175mm, the room temperature should be 23 ℃ ± 2 ℃, the relative humidity 50% ± 5 It was. The base material was coated with a pressure-sensitive adhesive on polyethylene terephthalate and UV-cured, and after 20 minutes to 24 hours, the substrate was measured by pressing with a roller of 2 kg on a stainless steel sheet. The measuring device was a universal material tester of Reputation Trading Corp., and was measured at a peel rate of 300 mm per minute.

2. Rolling Ball Test (PSTC-6)

The initial adhesive force is to find the adhesion force at the moment of adhering the tape to the adherend. Therefore, the adhesion of the surface becomes a problem. This method displays the adhesive force by the size of the maximum diameter of the ball, which is fixed by sticking the adhesive tape on a 30 ° inclined plate and rolling the ball from the top of 100 mm. For example, if a ball with a 20/32 inch radius is broken, the adhesive force is set to Ball No. 20. This experiment was measured three times or more and averaged.

3. Weather resistance test

A UVB-313 lamp (313 nm) of a Q-panel Accelerated Weathering Tester (QUV / se) was used to irradiate UV light at a temperature of 40 ° C. to test adhesion at different time zones.

4. Heat resistance test

The thermal stability was measured by leaving the coated adhesive under a temperature condition of 130 ° C. and measuring the adhesive force for each time zone.

Polymerization Example

Example 1-4 and Comparative Example 1

The ultraviolet curable pressure sensitive adhesive according to the present invention was polymerized in a composition as shown in Table 1.

The total polymerization was made of a solvent-type free radical reaction by a thermal initiator, and polymerization was carried out in two stages to prevent gelation due to excessive viscosity increase due to exothermic reaction, that is, excessive molecular weight.

In the polymerization composition shown in Table 1, about 70 parts by weight (monomer, modified monomer, solvent, functional group, photoinitiator) was raised to 75 ° C. using a four-necked reactor equipped with a stirrer, and then the initiator was 2 The reaction is carried out while stirring while stirring. The polymerization was carried out while gradually adding the remaining 30 parts by weight over 1 hour. Thereafter, the reaction was carried out for 4 hours to polymerize the ultraviolet curable pressure sensitive adhesive.

TABLE 1

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 n-butyl acrylate 46.5 46 42 37 47 Methyl methacrylate 5 5 5 5 5 Ethyl acetate 45 45 45 45 45 Methacrylic acid 1.5 1.5 1.5 1.5 1.5 Azobisisobutylonitrile 0.14 0.14 0.14 0.14 0.14 4-benzophenone diethylene glycol acrylate 0.5 0.5 0.5 0.5 0.5 Silicone acrylate 0.5 One 5 10 -

Example 5

The polymers according to Examples 1 to 4 and Comparative Example 1 were coated on a polyethylene terephthalate film, and then a little heat was removed to remove the solvent, followed by curing with an ultraviolet curing device. Curing conditions were coated with a bar coater with one 80 watt medium pressure mercury lamp at a fan belt speed of 3.5 meters per minute.

Example 6

The glass transition temperature, viscosity, and pyrolysis temperature of the formulations of Examples 1 to 4 and Comparative Example 1 were measured.

TABLE 2

Glass transition temperature (℃) Viscosity (cps) Pyrolysis Temperature (℃) Example 1 -44.3 6640 394.4 Example 2 -43.8 3960 394.7 Example 3 -42.3 2650 395.7 Example 4 -40.9 1440 396.6 Comparative Example 1 -47.6 12680 391.2

In general, the composition exhibiting adhesion at room temperature should have a glass transition temperature of about −30 ° C. or less of the entire copolymer. As shown in Table 2 it can be seen that the glass transition temperature of the polymer exhibits excellent adhesion at room temperature from -44.3 ° C to -40.0 ° C.

In addition, it was found that the viscosity decreases due to an increase in the content of the silicone acrylate. It is believed that this is because it is bonded to the silicon acrylate group in the molecular chain and serves to suppress the increase in molecular weight.

In pyrolysis temperature measurement, it can be seen that as the content of silicon acrylate increases, the heat resistance, which is a typical advantage of the silicone series, increases, resulting in an increase in pyrolysis temperature.

As a result of the above experiment, as the content of silicon increases, the initial adhesive strength decreases little by little, but the thermal stability increases and the viscosity decreases, making it easy to process and the performance of the adhesive changes stably.

Example 7

After coating curing by the method of Example 5, the peel force by thickness of the ultraviolet curable pressure-sensitive adhesive was measured in accordance with Test Method 1.

TABLE 3

Adhesive Thickness (㎛) Example 1 (gf / in) Example 2 (gf / in) Example 3 (gf / in) Example 4 (gf / in) Comparative Example 1 (gf / in) 9.1 20.2 19.8 14.9 12.4 35.7 32.0 28.9 23.9 18.7 15.0 39.8 50.0 35.5 33.8 27.2 20.3 49.2 77.7 72.2 62.3 57.2 46.7 83.8

Example 8

After coating curing by the method of Example 5, the adhesive strength for each thickness of the ultraviolet curing adhesive according to Test Method 2 was measured.

TABLE 4

Adhesive Thickness (㎛) Example 1 (Ball No.) Example 2 (Ball No.) Example 3 (Ball No.) Example 4 (Ball No.) Comparative Example 1 (Ball No.) 9.14 6 (6.6) 6 (7.1) 5 (9) 4 (4.8) 9 (7.5) 32 6 (5.8) 6 (6.5) 5 (7.5) 4 (4.3) 9 (4.9) 50 6 (2.2) 6 (5.2) 5 (4.3) 5 (8.2) 10 (7.3) 77.7 8 (5.9) 8 (7.3) 7 (6) 6 (4.7) 12 (5.7)

※ The number in the parenthesis is the distance the ball stopped: The unit is cm

In the experimental results of Examples 7 and 8, in the case of Comparative Example 1, as the thickness of the pressure-sensitive adhesive increases, a sudden change in adhesive force and peeling strength was observed, but as the content of silicone acrylate increased, The width gradually decreased. This shows that the silicone acrylate is included in the chain compared to the general acrylic adhesive, so that the peelability and the stability of the adhesive are excellent.

Example 9

After the pressure-sensitive adhesive was uniformly coated to 9.14 μm and cured, the UV-resistant change of the pressure-sensitive adhesive over time was measured according to Test Method 3.

TABLE 5

Hour Example 1 (Ball No.) Example 2 (Ball No.) Example 3 (Ball No.) Example 4 (Ball No.) Comparative Example 1 (Ball No.) 0 6 (6.6) 6 (7.1) 5 (9) 4 (4.8) 9 (7.5) 2 7 (5.3) 7 (9.8) 5 (2) 5 (8.9) 10 (4.2) 6 8 (6.4) 7 (5.7) 6 (3.8) 5 (5) 10 (2) 12 8 (8.7) 7 (5.3) 6 (4) 5 (5.4) 9 (8) 24 8 (9.8) 7 (6.1) 6 (6) 5 (6.5) 8 (7)

※ The number in the parenthesis is the distance the ball stopped: The unit is cm

As a result of testing the UV resistance, the adhesive force was increased by the heat of the UV lamp in the early stage, and in Comparative Example 1, the adhesive strength was decreased due to the photoaging of the adhesive chains as time passed. Examples 1 to 4 In the it was confirmed that as the content of the silicone acrylate increases, the adhesion to the ultraviolet rays is excellent.

Example 10

According to Test Method 4, the change in adhesion with time was measured.

Table [6]

Hour Example 1 (Ball No.) Example 2 (Ball No.) Example 3 (Ball No.) Example 4 (Ball No.) Comparative Example 1 (Ball No.) 0 6 (6.6) 6 (7.1) 5 (9) 4 (4.8) 9 (7.5) 2 8 (8.7) 7 (4) 5 (4.5) 5 (7.5) 10. (7) 6 8 (5.3) 8 (4.2) 6 (8) 5 (4.7) 11 (8) 12 9 (8.4) 8 (1.5) 6 (7.9) 5 (3.5) 11 (6) 24 10 (9.7) 9 (7) 6 (5.7) 5 (3) 11 (1.2)

※ The number in the parenthesis is the distance the ball stopped: The unit is cm

As the temperature increased, the fluidity of the adhesive chains increased, resulting in an increase in stickiness. In Comparative Example 1, although the increase in adhesive strength was increased, it was confirmed that the adhesive strength was more stable as the silicon acrylate content was increased in Examples 1 to 4.

The present invention is polymerized to include a silicone acrylate with a photoinitiator in the acrylic monomer to compensate for the disadvantages of the acrylic pressure-sensitive adhesive so that no residue remains after curing, and the advantages of acrylic-based low price and functional properties free of changes in properties and room temperature In addition, it is easy to polymerize and has the advantages of silicon-based weather resistance, heat resistance, and excellent peeling force. In addition, it has the advantage of having an environmentally friendly and fast production speed using ultraviolet curing.

Claims (7)

An ultraviolet curable pressure-sensitive adhesive composition comprising 100 parts by weight of an acrylic monomer, 0.1-10 parts by weight of a silicone acrylate based on 100 parts by weight of the acrylic monomer, and 0.1-10 parts by weight of a photopolymerization initiator having a functional group capable of participating in polymerization. The method of claim 1, wherein the acrylic monomer is methyl methacrylate, styrene, 2-ethylhexyl methacrylate, lauryl methacrylate, methyl acrylate, n- butyl acrylate, 2-ethylhexyl partially having an acrylic group UV curable pressure-sensitive adhesive composition, characterized in that at least one selected from the group consisting of methacrylate and ethyl acrylate. The method of claim 1, wherein the acrylic monomer comprises at least one main monomer selected from the group consisting of vinyl acetate, methyl methacrylate and styrene in 50 to 90 parts by weight of the acrylic monomer, 2-ethylhexyl methacrylate, At least one modified monomer selected from the group consisting of lauryl methacrylate, methyl acrylate, n-butyl acrylate and 2-ethylhexyl methacrylate as 10-14 parts by weight of the acrylic monomer, and acrylic acid, meta An ultraviolet curable pressure-sensitive adhesive composition comprising at least one functional monomer selected from the group consisting of acrylic acid, maleic acid, acrylamide, and glycidal methacrylate in an amount of 2-20 parts by weight of the acrylic monomer. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the silicone acrylate has a monofunctional or polyfunctional functional group and a molecular weight of 500,000 or less per functional group. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the photoinitiator is selected from at least one selected from the group consisting of benzophenone or benzophenone derivatives and thioxanthone or thioxanthone derivatives. The UV-curable pressure-sensitive adhesive composition of claim 1, wherein the photocurable pressure-sensitive adhesive composition has a molecular weight of 1,000,000 or less upon polymerization. An article cured by photocuring with the ultraviolet curable pressure-sensitive adhesive composition of claim 1.