KR20110072121A - Uv curing resin having good adhesion and products using the same - Google Patents

Abstract

PURPOSE: A UV curable resin composition is provided to improve shrinkage according to UV curing, adhesive property to a substrate, and durability of a product, and to realize products as a thin film. CONSTITUTION: A UV curable resin composition comprises a urethane acrylate oligomer, a reactive monomer, and a photoinitiator. The UV curable resin composition further includes one or more kinds of homopolymers or heteropolymers as an adhesion promoter, selected from the group consisting of ethyl acrylate, butyl acrylate, and 2-ethyl hexyl acrylate.

Description

UV curable resin with excellent adhesion and product using the same {UV CURING RESIN HAVING GOOD ADHESION AND PRODUCTS USING THE SAME}

 The present invention relates to an ultraviolet curable resin composition and a molded article thereof, and more particularly, to include a specific adhesion promoter of the ultraviolet curable resin composition, to significantly remove the shrinkage rate due to ultraviolet curing, to improve adhesion and to extend the life of the product. To provide a composition, the composition can be applied to electronic products, such as keypads, windows.

  In general, the trend toward miniaturization and slimming of electronic products and mobile phones is dominant. Accordingly, the demand for flat exteriors is increasing, and the application of the printing method increases the added value by providing functions such as various colors and touches. Accordingly, the demand for UV-curable resins that do not use organic solvents is increasing. An ultraviolet curable resin composition consists of an oligomer, a monomer, a photoinitiator, an additive, etc. When ultraviolet rays are irradiated to the ultraviolet curable paint, radicals are generated from the photoinitiator, and the generated radicals attack the double bonds of the oligomer and the monomer to cure while forming crosslinks of a three-dimensional network. Since the UV cured paint hardens in a short time compared to other paints to form a film, the time required for the process is short, productivity is excellent, and there is less environmental pollution because no volatile solvent is used.

However, UV curable resins have various advantages in environmental, productive, and aesthetic fields, but their shrinkage due to UV curing is necessarily involved in the manufacturing process, and shrinkage exhibits a limit in retaining durability by lowering the adhesion between the substrate and the UV curable resin. .

In order to improve the adhesion, conventional coating, corona discharge, plasma treatment was performed. While these methods increase adhesion, primer coating has problems with process increase, lot-to-lot performance variation, price increases, and corona discharge is expensive equipment, uneven quality control and plasma treatment are expensive equipment and process risks. Have

Therefore, the conventional ultraviolet curable resin composition reduces the adhesion between the substrate and the ultraviolet curable resin due to shrinkage due to ultraviolet curing, and solves the disadvantages of inferior durability, thereby reducing the shrinkage of the ultraviolet curable resin and improving the adhesion. There is still a need to provide compositions with an extended lifetime.

 The present invention improves the durability of the product by improving the adhesion of the substrate (PET, PC, PMMA) and the ultraviolet curable resin due to the shrinkage accompanying the manufacture of the exterior parts to improve the durability of the product and realized the UV curable resin composition To provide.

Another embodiment of the present invention is to provide an ultraviolet curable resin composition having excellent adhesion even without a pretreatment step for increasing the adhesion to the substrate such as primer coating, corona discharge, plasma discharge.

One embodiment of the present invention to provide a flat product that constitutes the appearance of the electronic products and mobile phone components to which the ultraviolet curable resin composition containing the adhesion promoter is applied.

One embodiment of the present invention is to provide a method for producing the ultraviolet curable resin composition.

The present invention relates to an ultraviolet curable resin composition comprising a urethane acrylate oligomer, a reactive monomer and a photoinitiator, wherein ethyl acrylate (EA), butyl acrylate (BA) and 2-ethylhexyl acrylate (2 -EHA, 2-Ethyl hexyl acrylate) relates to an ultraviolet curable resin composition comprising at least one homopolymer or heteropolymer selected from the group consisting of adhesion promoters.

Conventional UV curable resins have poor adhesiveness due to shrinkage that occurs during UV curing. Since this is closely related to the durability of the product, it has been pretreated to improve adhesion. However, the pretreatment process has problems such as an increase in the process, a risk of the process, and a price increase.

In order to solve the problems of conventional UV curable resins, the present invention adds the adhesion promoter to urethane acrylate, reactive monomer having two or three functional groups, photoinitiator, and additives. 2-EHA and EA added act as adhesion increasing oligomers to increase the durability of the product by increasing the adhesion and do not require a pretreatment process to increase the adhesion of existing UV-curable resins. It can solve the problem of price increase.

The present invention primarily comprises at least one selected from the group consisting of ethyl acrylate (EA), butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA, 2-Ethyl hexyl acrylate). Homopolymers or heteropolymers are first synthesized as adhesion promoters. After that, prior to the existing urethane acrylate (urethane acrylate) by adding an oligomer that can improve the adhesion to prepare a UV-curable resin. Physical performance was evaluated according to the amount of adhesion increase oligomer added at a certain component ratio to determine the optimum amount of addition and the increase of the physical properties accordingly.

The present invention is suitable for flat products among various forms of electronic parts and mobile phone parts, and is particularly excellent in application to parts of the exterior which are subjected to continuous stress of mobile phones or electronic products. The present invention uses an ultraviolet curable resin and significantly improves the adhesion of the substrate (PET, PC, PMMA) and the ultraviolet curable resin due to the shrinkage accompanying the manufacture of the exterior parts, thereby improving the durability of the product and making the product into a thin film. By implementing various functions, it is aesthetically beautiful and suitable for the manufacture of slim products.

The ultraviolet curable resin composition may further include various additives, including a main oligomer, a monomer, and a photoinitiator.

Preferably, the UV curable resin composition may include 50 to 120 parts by weight of reactive monomer, 1.0 to 60 parts by weight of adhesion promoter, and 1.0 to 10.0 parts by weight of photoinitiator, based on 100 parts by weight of the urethane acrylate oligomer.

The present invention may be at least one homopolymer or heteropolymer selected from the group consisting of EA (Ethyl acrylate), BA (Butyl acrylate) and 2-EHA (2-Ethyl hexyl acrylate) as an adhesion promoter to the UV-curable resin composition, Preferably, it may be a heteropolymer of 2-ethylhexyl acrylate (2-Ethylhexyl acrylate, 2-EHA) and ethyl acrylate (Ethyl acrylate, EA).

The adhesion promoter may include 1.0 to 60 parts by weight, preferably 1.5 to 55, more preferably 14 to 30 parts by weight based on 100 parts by weight of the urethane acrylate oligomer, the content of the adhesion promoter is urethane acrylate oligomer 100 If it is less than 1.0 part by weight, it is difficult to expect a change in the physical properties of the ultraviolet curable resin, and if it exceeds 60 parts by weight, it is too soft, so that the physical properties of the adhesion enhancer are expressed so much that it loses the intrinsic properties of the ultraviolet curable resin and is durable. This drastically decreases, making it impossible to use the exterior parts.

The adhesion promoter is at least one selected from the group consisting of ethyl acrylate (Ethyl acrylate, EA), butyl acrylate (Butyl acrylate, BA) and 2-ethylhexyl acrylate (2-EHA, 2-Ethyl hexyl acrylate) It may be a homopolymer or a heteropolymer. The molecular weight of the adhesion promoter is an oligomer of 1,000 to 20,000. It is particularly preferred to have a molecular weight between 4,500 and 10,000. For example, it is an oligomer of 2-ethylhexyl acrylate (2-EHA) and ethyl acrylate (Ethyl acrylate, EA), the preferred molecular weight is 1,000 to 20,000 oligomer, especially molecular weight between 4,500 to 10,000. It is preferable to have. The adhesion promoter may be a copolymer of 25 to 75 parts by weight of 2-ethylhexyl acrylate and 75 to 25 parts by weight of ethyl acrylate, preferably 30 to 70 parts by weight of 2-ethylhexyl acrylate and 70 to 70 parts by weight of ethyl acrylate. 30 parts by weight may be polymerized.

 The reactive monomer can be used in the ultraviolet curable resin composition, for example, preferably two or three functional groups. The content of the reactive monomer is 50 to 120 parts by weight, based on 100 parts by weight of the urethane acrylate oligomer, preferably 70 to 85 parts by weight. The content of the reactive monomer may be determined in consideration of the physical properties of the final product.

Examples of the functional group include, but are not limited to, acrylate, carboxyl group, and the like. Examples of preferred reactive monomers applicable to the present invention include 1, 6-hexanediol diacrylate (1, 6-hexane diol diacrylate (HDDA)), trimethylolpropane triacrylate (TMPTA) It can select from above and can use individually or in mixture. Preferred examples of the reactive monomer may be used by mixing in a weight ratio of HDDA and TMPTA 40-60%: 60 to 40.

The photoinitiator may be used in an amount of 1.0 to 10.0 parts by weight, preferably 2 to 6 parts by weight, based on 100 parts by weight of the urethane acrylate oligomer, and may be determined in consideration of the reaction rate, production efficiency, and the concern of generation of unreacted material. When the photoinitiator is excessively used, it is difficult to produce a uniform product having a certain performance by instant curing with a very fast reaction rate.

Examples of the photoinitiator include 1-hydroxy cyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl propane-1-ketone (2-Hydroxy-2-methyl-1 -phenyl propane-1-ketone), 2-chlorothioxantone and 2-isopropyl thioxanthone-based compounds may be used alone or in combination. However, the present invention is not particularly limited thereto. For example, the photoinitiator may use 1-hydroxy cyclohexyl phenyl ketone in consideration of reaction rate and physical properties, productivity to maintain uniform quality, and cost. .

In addition, the composition of the present invention may include 0.1 to 5.0 parts by weight of one or more additives selected from the group consisting of antifoaming agents, pigments and labeling agents based on 100 parts by weight of the urethane acrylate oligomer.

In addition, the present invention is to provide a product produced by applying the ultraviolet curable resin composition to a resin substrate. The resin substrate may include PET, PC, PMMA, and the like, and the coating thickness of the ultraviolet curable resin composition may be a thickness applied to the appearance of a conventional flat product. The product may be a flat product among various forms of electronic parts and mobile phone parts, and in particular, may be a part of an exterior product that receives continuous stress of a mobile phone or an electronic product. The product of the present invention can significantly improve the adhesion of the resin substrate and the ultraviolet curable resin to improve the durability of the product and implement the product in a thin film, while providing a variety of functionality, while providing aesthetically beautiful and slim product. Specifically, the UV-curable resin with improved adhesion is applied to flat products such as mobile phones, windows, keypads, logos, refrigerator front panels, and touch pad windows. It is possible to put a logo on the surface of the product by adhering or applying UV-curable resin to the surface of the product in letter or desired shape and irradiating it with UV rays.

The present invention improves the durability of the product while increasing the adhesion by changing the properties of the ultraviolet curable resin without any pre-treatment, it can be usefully applied to electronic products such as keypads, windows.

The present invention will be described in more detail with reference to the following examples, but the following examples are provided by way of example only, and are not intended to limit the protection scope of the present invention.

Example 1

1-1 Selection of Candidate Enhancer

In order to increase the adhesion with the substrate (PET, PC, PMMA), first, the adhesion increasing oligomer is synthesized. The monomers used in the synthesis of the oligomer are EA (Ethyl acrylate), BA (Butyl acrylate), 2-EHA (2-Ethyl hexyl acrylate), EMA (Ethyl methacrylate), BMA (Butyl methacrylate), 2-EHMA ( 2-Ethyl hexyl methacrylate), AA (Acrylic acid), MAA (Methacrylic acid) and the like can be used to prepare oligomers and to measure the reaction rate, adhesion and hardness.

[Table 1] Adhesion Promoter

division AA MAA EA BA 2-EHA EMA BMA 2-EHMA Reaction speed ○ ○ ○ ○ ○ x x x Adhesive ○ ○ ○ ○ ○ ○ ○ ○ Hardness Destruction Destruction Soft Soft Soft Destruction Destruction Destruction

As a method of measuring the reaction rate, the contents of the reactants explode while initially forming bubbles, and after a certain time, bubbles disappear and the reaction tends to stabilize. If the reaction is continuously maintained, the reactant becomes viscous and the molecular weight increase can be visually confirmed. After the completion of the termination reaction by cooling and odor was measured by the sensory method to check the reaction rate. The methacrylate series was not suitable for use due to the slow reaction rate due to the large amount of unreacted monomers.

As a measuring method of adhesion, a specimen was prepared by coating a synthetic adhesion promoter on a 28 micrometer PET film with a dry basis of 100 μm. The produced PET film is kept for 10 minutes in an oven at 110 ℃. After standing at room temperature for 4 hours, the adhesiveness was measured by a crosscut method using 3M Scotch tape. After peeling 5 times, it was confirmed that there was no damage and the adhesion was excellent.

The hardness was measured using a shore hardness tester. According to Table 1, AA, MAA, EMA, BMA, and 2-EHMA were too hard to be destroyed when measured, and EA, BA, and 2-EHA were too soft to measure numerical values. The exact figures were not known, but they were able to distinguish between soft and hard.

The required physical properties of the adhesion promoter are to improve the adhesion of the ultraviolet curable resin, which is a hard viscoelastic material at room temperature. AA, MAA having a carboxyl group showed a solid state at room temperature. It was found that the glass transition temperature of each monomer was much higher than room temperature, indicating the physical properties of the solid. In addition, the methacryl-based compound has a very strong odor of the unreacted monomer due to the slow reaction rate due to the steric hindrance possessed by the monomer itself. In addition, homopolymers exhibited a solid character at room temperature. It was confirmed that the glass transition temperature of its own originates from room temperature or higher.

Thus, at least one homopolymer selected from the group consisting of ethyl acrylate (EA), butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA, 2-Ethyl hexyl acrylate) or A heteropolymer may be used as an adhesion promoter, and a heteropolymer of EA (Ethyl acrylate) and 2-EHA (2-Ethyl hexyl acrylate) is preferable.

Preparation and Properties of Heteropolymers of 1-2-2EHA and EA

By adjusting the heteropolymer ratio of 2-EHA (2-Ethyl hexyl acrylate) and EA (Ethyl acrylate) in various ways at 85 ° C. for 4 hours, heteropolymers A, B, and C were prepared. The compatibility, storage stability, and physical properties of were measured and the results are shown in Table 3 below.

 Methods of measuring compatibility, storage stability and physical properties are as follows. Compatibility and storage stability were visually confirmed, and physical properties were measured by tack test method. A 38 μm PET film was coated with a dry polymer of 100 μm on a dry basis to prepare a specimen. Rolling balltack was measured by j-dow method to measure balltack. The molecular weights of heteropolymers A, B, and C were 5540, 7860, and 9650 of heteropolymers A, B, and C, respectively. As the molecular weight increased, Ball No increased to 4, 8, and 15, respectively, of heteropolymers A, B, and C. It was confirmed that the adhesion is excellent.

TABLE 2 Heteropolymers of 2-EHA and EA

2-EHA (wt%) EA (wt%) Compatibility Storage stability Physical properties
(Ball No) Heteropolymer A 30 70 Yellow and transparent No phase separation 4 Heteropolymer B 50 50 transparent No phase separation 8 Heteropolymer C 70 30 transparent No phase separation 15

Considering the stability of the reaction and the compatibility with the UV-curable resin after the reaction rate, storage stability, physical properties, it was found that the heteropolymer C, Ball No 15, which is colorless and transparent, has no phase separation, and has the best adhesion.

Examples 2-4

 As shown in Table 3 below, the main urethane acrylate oligomer, the adhesion promoter (heteropolymer C prepared in Example 1), the reactive monomer and the photoinitiator were combined and reacted at 85 ° C. for 4 hours in an ultraviolet curing device for UV curing. Resin was prepared.

The prepared UV curable resin was coated with a UV curable resin having a thickness of 300 μm on a square PET film having a width of 200 mm, a length of 200 mm, and a thickness of 120 μm to prepare a specimen. Adhesion test, reliability test for continuous stress, and hardness test were performed on the specimen.

(1) Adhesion Test (Cross Cut)

The number of hard coating layers remaining in the substrate when 100 cross-hatches of 1 mm ㅧ 1 mm were put on the surface of the hard coating layer and the cellophane adhesive tape was attached and then removed.

(2) Reliability test by continuous stress

 After 24 hours of storage in an oven at 80 ° C and 80% humidity, remove for 3 hours at room temperature, and cross-test.

(3) hardness measurement

Hardness was measured using a Shore hardness tester.

Table 3 Formulation of UV Curable Resin Composition

division Kinds Comparative Example 1 Example 2 Example 3 Example 4 Topic oligomers Urethane acrylate 100 100 100 100 Adhesion promoter 2-EHA (70wt%): EA30wt%) 1.66 9.09 20 50 Reactive monomer HDDA (50wt%:
TMPTA (50 wt% 66.66 72.72 80 100 Photoinitiator 1-Hydroxy cyclo hexyl phenyl ketone) 5 5.54 6 7.5 additive modified polysiloxanes 0.33 0.36 0.4 0.5

a) 1, 6-hexanediol diacrylate (1, 6-hexane diol diacrylate (HDDA)) and trimethylolpropane triacrylate (TMPTA) as a reactive monomer when used alone or in combination to improve the soft properties If you want to increase the content of bifunctional 1, 6-hexane diol diacrylate (1, 6-hexane diol diacrylate (HDDA) and hard properties if you want to increase the trifunctional functional trimethylolpropane triacrylate (TMPTA) You can adjust the mixing ratio according to the desired properties of the product you want to make by increasing the amount.

UV-curable resins are inferior in adhesion even if they are too soft and poor in adhesion even if they are too hard. Therefore, the mixing ratio of HDDA and TMPTA is 50wt%: 50wt% to make the intermediate state between soft and hard, which is the property of viscoelastic material with the best adhesion. It was set as.

As the additive, A-3030 (modified polysiloxanes) of Poschem Co., Ltd. was used. The main oligomer was SU5020 (aliphatic urethane diacrylate with buthyl acetate) manufactured by POS Chemical.

Comparative Example 1

The ultraviolet curable resin was prepared in the same manner as in Example 2, except that the anti-adhesive agent was not included. The contents of the main urethane acrylate oligomer, the reactive monomer, the photoinitiator and the additive are shown in Table 3. The adhesion test, the reliability test for continuous stress, and the hardness measurement test of the prepared UV curable resin were performed, and the results are shown in Table 4.

[Table 4] Properties of UV Curable Resin

division Comparative Example 1 Example 2 Example 3 Example 4 Adhesion 4 peels damaged No damage after 5 peels No damage after 5 peels No damage after 5 peels responsibility 4 peels damaged No damage after 5 peels No damage after 5 peels No damage after 5 peels Hardness 80 70 65 55

In the adhesive force test (crosscut) test, the resin of Comparative Example 1 containing no adhesion promoter was only 4 times when 100 1 mm 칭 1 mm cross hatching was put on the surface of the hard coating layer, and then peeled off five times after attaching the cellophane adhesive tape. On the other hand, the newly developed ultraviolet curing resins of Example 2, Example 3, and Example 4 did not cause any damage.

In the reliability test by continuous stress, after 24 hours of storage in an oven at 80 80C and 80% humidity, it was taken out and left for 3 hours at room temperature. Then, 100 cross-hatches of 1mm ㅧ 1mm were put on the surface of the hard coating layer, and cellophane adhesion was performed. When the adhesive was removed 5 times after attaching the tape, Comparative Example 1, in which the adhesion promoter was not damaged, was damaged twice, whereas in Example 2, Example 3, and Example 4, which were newly developed UV curing resins, 5 times were removed. There was no problem afterwards.

Through the above examples, it was confirmed that the adhesion was improved when the adhesion increase oligomer was added without any pretreatment, and according to Table 3, Example 6 having 10 weight parts of the adhesion increase oligomer added had the most ideal physical properties. Could know.

Claims (10)

UV-curable resin composition comprising a urethane acrylate oligomer, a reactive monomer and a photoinitiator, comprising ethyl acrylate (Ethyl acrylate, EA), butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA, UV-curable resin composition comprising at least one homopolymer or heteropolymer selected from the group consisting of 2-Ethyl hexyl acrylate) as an adhesion promoter. The ultraviolet curable resin composition of claim 1, wherein the ultraviolet curable resin composition comprises 50 to 120 parts by weight of reactive monomer, 1.0 to 60.0 parts by weight of adhesion promoter, and 1.0 to 10.0 parts by weight of photoinitiator, based on 100 parts by weight of the urethane acrylate oligomer. Resin composition. According to claim 1, wherein the adhesion promoter UV curable resin composition comprising 1.5 to 55 parts by weight based on 100 parts by weight of the urethane acrylate oligomer. According to claim 1, wherein the adhesion promoter UV-curable resin composition having a molecular weight of 1,000 to 20,000. The UV curable resin composition according to claim 1, wherein the adhesion promoter is a copolymer of 25 to 75 parts by weight of 2-ethylhexyl acrylate and 75 to 25 parts by weight of ethyl acrylate. The ultraviolet curable resin composition according to claim 1, wherein the reactive monomer is 1, 6-hexanediol diacrylate or TMPTA, wherein the functional group is an acrylate or a carboxyl group and has two or three functional groups in one molecule. The UV curable resin composition according to claim 6, wherein the reactive monomer is a mixture of 1,6-hexanediol diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA). . The ultraviolet curable resin composition according to claim 1, wherein the photoinitiator is 1-hydroxy cyclohexyl phenyl ketone. The ultraviolet curable resin composition of claim 1, wherein the ultraviolet curable resin composition comprises 0.1 to 5.0 parts by weight of at least one additive selected from the group consisting of an antifoaming agent, a pigment, and a labeling agent based on 100 parts by weight of the urethane acrylate oligomer. A product having a resin coating layer prepared by applying the ultraviolet curable resin composition according to any one of claims 1 to 9 on a resin substrate.