CN111171705A

CN111171705A - UV gloss oil and preparation method and application thereof

Info

Publication number: CN111171705A
Application number: CN202010070299.3A
Authority: CN
Inventors: 孙世超; 崔鸿雁
Original assignee: Shandong Brett Ink Co ltd
Current assignee: Shandong Brett Ink Co ltd
Priority date: 2020-01-21
Filing date: 2020-01-21
Publication date: 2020-05-19

Abstract

The invention relates to UV gloss oil and a preparation method and application thereof, wherein the gloss oil comprises the following raw materials, by weight, 25-50% of oligomer; 39% -60% of monomer; 5-8% of a leveling agent; 3-6% of photoinitiator; wherein the number of the functionalities of the oligomer is 2-3, the leveling agent is selected from cellulose acetate leveling agents, and the monomer is selected from one or more of trimethylolpropane triacrylate, tripropylene glycol diacrylate and 1, 6-hexanediol diacrylate. According to the UV gloss oil provided by the invention, the oligomer is used as one of the main film forming raw materials, and the number of the functionalities of the oligomer and the use of the matched monomer are adjusted, so that a paint film formed by the prepared gloss oil can have a good release effect and a good recoating effect; in addition, the cellulose acetate substance is adopted as the leveling agent, so that the gloss oil has a good leveling effect, and the release effect of a paint film formed by the gloss oil can be further improved.

Description

UV gloss oil and preparation method and application thereof

Technical Field

The invention relates to the field of printing ink, in particular to UV gloss oil and a preparation method and application thereof.

Background

Flexography is a direct printing method, called flexography, because of the use of an elastic, raised image plate. The flexography is beneficial to environmental protection, meets the hygienic standard of food packaging presswork, and is developed rapidly abroad. However, in the domestic packaging printing industry, flexography starts later than offset printing and gravure, but with the national emphasis on environmental protection, flexography is rapidly developed. Especially for printing of some label products, there is a great demand.

In the flexographic printing, gloss oil is usually required to be printed to form a paint film to protect a printed pattern, and meanwhile, the paint film is endowed with good release property to meet the printing requirements of some labels and even anti-counterfeiting information. The UV gloss oil is a novel gloss oil, and a formed paint film has extremely high fullness, brightness and excellent wear resistance and oil resistance.

However, the existing UV gloss oil mainly adopts solvent type gloss oil, and the solvent type gloss oil also adopts benzenes, esters and alcohols as solvents or diluents, so that the realization of the gloss oil preparation process is facilitated. The gloss oil product has high solvent content, the printing and curing processes are carried out on the printing surface, and the volatilization of the solvent causes certain pollution to the environment and damages the health of operators. In addition, the gloss oil layer (i.e. paint film) formed by the solvent-based UV gloss oil through the flexography is poor in release effect on the base material, so that the application effect of a printed product is influenced, and the UV gloss oil and the further application thereof in the flexography are also hindered.

Disclosure of Invention

The UV gloss oil provided by the invention can enable a formed paint film to have a good release effect and have the advantage of environmental friendliness through matching of raw material compositions, selection of the functionality quantity of film-forming substances, selection of monomer types and selection of flatting agents.

The invention further provides a preparation method of the UV gloss oil, which controls the process conditions according to the characteristics of the selected raw materials to obtain the UV gloss oil which has no pollution to the environment and better release effect.

The invention further provides a use method of the UV gloss oil.

The UV gloss oil is prepared from the following raw materials in percentage by weight:

oligomer, 25-50%;

39-60% of monomer;

5-8% of a leveling agent;

3-6% of photoinitiator;

wherein the number of the functionalities of the oligomer is 2-3, the leveling agent is selected from cellulose acetate leveling agents, and the monomer is selected from one or more of trimethylolpropane triacrylate, tripropylene glycol diacrylate and 1, 6-hexanediol diacrylate.

The UV gloss oil is one or two selected from urethane acrylate oligomer and epoxy acrylate oligomer;

the UV gloss oil as described above, said oligomer having a molecular weight of 2200 to 4100.

The UV gloss oil is characterized in that the cellulose acetate leveling agent is selected from cellulose acetate butyrate.

UV gloss oil as described above, the photoinitiator being selected from one or more of 1-hydroxy-cyclohexyl-phenyl-methanone, 2-hydroxy-methylphenyl propane-1-one and 2, 4, 6-trimethylbenzoyl-diphenylphosphine oxide.

The UV gloss oil is prepared by respectively dissolving the photoinitiator and the leveling agent by using the monomers and then mixing.

The UV gloss oil comprises the following raw materials:

2-10% of active amine photosensitive promoter.

The invention also provides a preparation method of any one of the UV gloss oil, which comprises the following steps:

mixing part of monomers with a photoinitiator, heating and stirring to dissolve the photoinitiator to obtain a mixture A;

mixing and stirring the leveling agent and part of monomers to dissolve the leveling agent to obtain a mixture B;

and mixing the mixture A, the oligomer, the mixture B and the balance of monomers, and filtering to obtain the UV gloss oil.

In the preparation method, when the mixture A, the oligomer, the mixture B and the balance of monomers are mixed, the active amine photosensitive promoter is also added.

The invention also provides a using method of the UV gloss oil, which is characterized in that the UV gloss oil is printed on the surface of a base material and is cured to form a paint film; preferably, the printing is flexographic printing.

According to the UV gloss oil provided by the invention, the oligomer is used as one of the main film forming raw materials, the number of the functionalities of the oligomer is 2-3, and the oligomer is matched with the monomer for use, so that a paint film formed by the prepared gloss oil can have a good release effect and a good recoating effect; in addition, the cellulose acetate substance is adopted as the leveling agent, so that the gloss oil has a good leveling effect, and the release effect of a paint film formed by the gloss oil can be further improved.

Therefore, the novel UV gloss oil provided by the invention does not need to add a solvent or a diluent in a preparation raw material, so that the novel UV gloss oil is high in solid content, has good release, recoat and other properties, and greatly reduces organic matter emission no matter in the preparation, storage and transportation processes or in the printing and curing processes, namely, the novel UV gloss oil provided by the invention is excellent in performance and environment-friendly.

Furthermore, the invention also sets a corresponding preparation process for the gloss oil, and the process is simple to operate, reduces the production cost and is suitable for industrial production.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The UV gloss oil provided by the invention comprises the following raw materials in percentage by weight:

oligomer, 25-50%;

39-60% of monomer;

5-8% of a leveling agent;

3-6% of photoinitiator.

In some embodiments of the present invention, no diluent or solvent is used in the composition of the raw materials of the gloss oil, so the main raw materials (oligomers and monomers) are used directly as raw materials without dilution.

The oligomer serves as a matrix resin in the UV gloss oil of the present invention and constitutes the basic skeleton thereof. Under light conditions, the oligomer has further reactive or polymeric groups such as C ═ C double bonds, epoxy groups, and the like. In the embodiment of the invention, the inventor finds out through experiments that the functionality quantity of the oligomer can be used for adjusting the hardness of the gloss oil after film forming, and also can be used for adjusting the release effect and the recoating effect of the gloss oil after film forming. "release" as used herein and hereinafter means that the varnish-formed paint film is attached to the substrate and separated therefrom when necessary; "recoat" refers to the ease and effectiveness of recoating with the same varnish or different varnishes after the paint film surface has dried.

In the embodiment of the present invention, the oligomer has a functionality number of 2 to 3, and the oligomer having a functionality number within this range makes it difficult for the varnish-formed paint film to crack, and can further improve the release effect and recoat effect. If the number of the functionalities of the oligomer exceeds 3, a paint film formed by the gloss oil prepared from the oligomer is brittle and easy to crack, and the release effect and the recoating effect are also reduced; if the number of the functional groups of the oligomer is less than 2, the prepared varnish forms a varnish film with strong adhesion to a substrate, and the release effect of the varnish film is reduced.

In some embodiments, the oligomer may be an acrylate oligomer. Further, the acrylate oligomer is selected from the group consisting of urethane acrylate oligomer and epoxy acrylate oligomer. These may be used alone or in combination of two.

In some embodiments, the functionality number of the urethane acrylate oligomer or the epoxy acrylate oligomer is 2.

Furthermore, the mixture of the two is used as the oligomer raw material, so that a paint film formed by the gloss oil has better release effect, recoating effect and performance of difficult cracking, and the production cost can be reduced and the water resistance can be improved.

The inventors have also found that, for the selected oligomer raw material, it is advantageous to have a suitable molecular weight to provide flexibility to the paint film, thereby further ensuring printability for further printing and integrity of the pattern on the article. For example, too low a molecular weight (smaller polymeric molecules) may affect the release effect of the paint film due to its strong adhesion to the substrate, and too high a molecular weight may also result in a cured paint film that is brittle, easily cracks, and is not conducive to the release effect.

In some embodiments, it may be advantageous to select oligomers having a molecular weight in the range of 2200 to 4100.

In some embodiments, difunctional urethane acrylate oligomers are selected that meet the above molecular weight ranges, with molecular weights of about 2800, 3000, 4100, and the like, difunctional epoxy acrylate oligomers are selected with molecular weights of about 2200, which may be, but are not limited to, Changxing 6151, Changxing 6152A-80. The above oligomer starting materials are all commercially available.

In some embodiments, the monomer is present in an amount of 39% to 60% by weight, based on 100% by weight of the sum of the raw material contents in the gloss oil, and the monomer in this range can further improve the release effect of the paint film formed from the gloss oil.

Further, in some embodiments, the monomer may be an acrylate monomer, and in particular may be selected from trimethylolpropane triacrylate, tripropylene glycol diacrylate, and 1, 6-hexanediol diacrylate. These may be used alone or in combination of two or more.

In a particular embodiment, the monomer is a mixture of trimethylolpropane triacrylate, tripropylene glycol diacrylate and 1, 6-hexanediol diacrylate, which not only further increases the release effect of the varnish-forming paint film, but also increases the flexibility of the paint film.

Furthermore, in order to meet the requirements of different customers on the release effect and the flexibility of the photo-oil formed paint film, the release effect and the flexibility can be realized by adjusting the proportions of different types of monomers. For example 49% by weight of trimethylolpropane triacrylate and 7% by weight of tripropylene glycol diacrylate, 35% by weight of trimethylolpropane triacrylate and 7% by weight of tripropylene glycol diacrylate, 24% by weight of trimethylolpropane triacrylate and 27% by weight of tripropylene glycol diacrylate, 44% by weight of trimethylolpropane triacrylate and 7% by weight of tripropylene glycol diacrylate and 25% by weight of trimethylolpropane triacrylate, 15% of tripropylene glycol diacrylate and 6% of 1, 6-hexanediol diacrylate.

In an embodiment of the present invention, the leveling agent is selected from cellulose acetate-based leveling agents including common cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate. The specific specification of the cellulose acetate is not limited. Based on the fact that the sum of the weight percentages of the raw materials in the gloss oil is 100 percent, and the weight percentage of the cellulose acetate leveling agent is 5-8 percent, the prepared gloss oil has good leveling property, and surprisingly, the release effect of the prepared gloss oil after a paint film is formed can be further improved.

In a specific embodiment, the cellulose acetate leveling agent is cellulose acetate butyrate, which may be, but is not limited to, the eastman CAB-551 series products, such as CAB-551-0.01, CAB-551-0.2, and the like.

In the embodiment of the invention, the weight percentage of the photoinitiator is 3-6% based on the sum of the weight percentage of the raw materials in the gloss oil being 100%, so that the photoinitiator not only can absorb ultraviolet light to generate free radicals and further initiate polymerization reaction, but also can improve the curing and surface drying effects of a paint film formed by the gloss oil.

In some embodiments, the photoinitiator is selected from the group consisting of 1-hydroxy-cyclohexyl-phenyl-methanone, 2-hydroxy-methylphenyl propane-1-one, and 2, 4, 6-trimethylbenzoyl-diphenyl phosphine oxide. These may be used alone or in combination of two or more.

In some embodiments, in view of the high cost of the photoinitiator, a photoinitiator accelerator is added to the raw materials of this embodiment to reduce the amount of the photoinitiator or to increase the reaction efficiency of the photoinitiator, thereby reducing the production cost. In some embodiments, the photosensitizing accelerator is a reactive amine photosensitizing accelerator.

Oxygen inhibition can also occur during the preparation of the gloss oil in the embodiments of the present invention, and can cause a large amount of oxidative structures such as hydroxyl, carbonyl, peroxy, etc. on the surface of the paint film, thereby affecting the long-term stability of the paint film, and even possibly affecting the properties such as hardness, glossiness and scratch resistance of the cured paint film. Therefore, the addition of the active amine photosensitive promoter can effectively inhibit oxygen inhibition and can also accelerate the surface drying rate of a paint film. In the embodiment, the weight percentage of the active amine photosensitive promoter is 3-5% based on the total 100% of the weight percentage of the raw material content in the gloss oil, so that the weight percentage content of the photoinitiator can be reduced by 1-2%, and the aim of reducing the production cost is fulfilled.

In some embodiments, the active amine photosetting promoter may be a tertiary amine photosetting promoter, such as triethylamine, triethanolamine, methyldiethanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, ethyl (2-dimethylamino) benzoate, michelson, 4-diethylaminobenzophenone, and the like. The tertiary amine photosensitive accelerator can generate photosensitive synergistic effect with the photoinitiator, can improve the photocuring rate of the colored ink system, and can also reduce the dosage of the photoinitiator.

In a specific embodiment, the active amine photostimulable agent used may be, but is not limited to, Boxing B-21 in Guangdong and Dada 1113D in Zhongshan.

mixing part of monomer and photoinitiator, heating and maintaining stirring until the photoinitiator is fully dissolved in the monomer, wherein in actual operation, the heating temperature and stirring conditions can be controlled according to the property of the used photoinitiator, for example, stirring at 500rpm/min for about 30min, and heating to 120 ℃ to fully dissolve the photoinitiator to obtain a mixture A;

and mixing the leveling agent with part of the monomers, maintaining stirring to fully disperse the leveling agent, and stirring at 600rpm/min for about 30min to obtain a mixture B.

And mixing the oligomer, the mixture A, the mixture B and the balance of monomers, stirring at the speed of 400r/min for 20min, and filtering by using a 200-mesh filter screen to obtain the UV gloss oil product.

In another embodiment, when the raw material comprises the photosensitive promoter, the preparation method further comprises adding the photosensitive promoter when the mixture A, the oligomer, the mixture B and the balance of the monomers are mixed, and preparing the UV gloss oil.

The invention also provides a using method of the UV gloss oil, which is used for printing the UV gloss oil on the surface of a base material to form a paint film through curing.

Specifically, the UV varnish is printed on the surface of a base material by a printing method known in the art, and is cured by ultraviolet irradiation with the wavelength of 200nm-400nm, so that the surface is hardened to form a paint film, and then a pattern is printed on the surface of the paint film to form a finished product. In particular, flexographic printing processes may be used. The varnish in the invention forms a varnish film with better release effect by flexographic printing, and makes better bedding for subsequent pattern printing operation, thus greatly improving the working efficiency.

The material of the substrate may be, but is not limited to, polyethylene terephthalate (PET), laminated paper, and an aluminum-plated film.

Hereinafter, the present invention is further illustrated by examples, but the present invention is not limited thereto.

Example 1

Based on the total amount of the raw materials, the raw material composition, the weight percentage of each component and the molecular weight of part of the components of the UV gloss oil are as follows:

oligomer: 35 percent of

A difunctional urethane acrylate oligomer having a molecular weight of 4100;

monomer (b): 56 percent

49% of trimethylolpropane triacrylate, 7% of tripropylene glycol diacrylate;

leveling agent: 3 percent of

Cellulose acetate butyrate (Istman CAB-551-0.01);

photoinitiator (2): 6 percent of

5% of 2-hydroxy-methylphenylpropanophenone, 1% of 2, 4, 6-trimethylbenzoyl-diphenylmethylphosphine oxide.

The preparation method of the UV gloss oil comprises the following steps:

1) mixing the monomers with a photoinitiator according to the following ratio of 1: 1, stirring at 500rpm/min for about 30min, and heating to about 120 ℃ to fully dissolve a photoinitiator to obtain a mixture A;

2) and (3) mixing the flatting agent and the monomer according to the ratio of 1: 2, and stirring at 600rpm/min for about 30min to fully dissolve the leveling agent to obtain a mixture B.

3) And mixing the oligomer, the mixture A, the mixture B and the balance of monomers, stirring at the speed of 400r/min for 20min, and filtering by using a 200-mesh filter screen after stirring to obtain the UV gloss oil.

Example 2

oligomer: 40 percent of

A difunctional urethane acrylate oligomer having a molecular weight of 2800;

monomer (b): 42 percent of

35% trimethylolpropane triacrylate, 7% tripropylene glycol diacrylate;

leveling agent: 3 percent of

Cellulose acetate butyrate;

photoinitiator (2): 5 percent of

3.5% of 2-hydroxy-methylphenylpropanophenone, 1.5% of 2, 4, 6-trimethylbenzoyl-diphenylmethylphosphine oxide;

active amine photosensitizing accelerator: 10 percent.

The preparation of example 2 is essentially the same as that of example 1, except that when the oligomer, mixture a and mixture B are mixed, an active amine photosensitizing accelerator is added.

Example 3

oligomer: 35 percent of

A difunctional urethane acrylate oligomer having a molecular weight of 3000;

monomer (b): 51 percent

24% trimethylolpropane triacrylate, 27% tripropylene glycol diacrylate;

leveling agent: 3 percent of

Cellulose acetate butyrate;

photoinitiator (2): 5 percent of

active amine photosensitizing accelerator: 6 percent.

The preparation method of example 3 is the same as that of example 2.

Example 4

oligomer: 35 percent of

Difunctional urethane acrylate oligomer with molecular weight of 4100 and 20 percent and difunctional epoxy acrylate oligomer with molecular weight of 2200 and 15 percent;

monomer (b): 51 percent

44% trimethylolpropane triacrylate, 7% tripropylene glycol diacrylate;

leveling agent: 3 percent of

Cellulose acetate butyrate;

photoinitiator (2): 5 percent of

2% of 2-hydroxy-methylphenylpropanophenone, 1.5% of 2, 4, 6-trimethylbenzoyl-diphenylmethylphosphine oxide, 1.5% of 1-hydroxy-cyclohexyl-phenylmethanone;

active amine photosensitizing accelerator: 6 percent.

The preparation method of example 4 is the same as that of example 2.

Example 5

oligomer: 35 percent of

A bifunctional urethane acrylate oligomer with a molecular weight of 3000 and 20 percent, and a bifunctional epoxy acrylate oligomer with a molecular weight of 2200 and 15 percent;

monomer (b): 51 percent

24% trimethylolpropane triacrylate, 27% tripropylene glycol diacrylate;

leveling agent: 3 percent of

Cellulose acetate butyrate;

photoinitiator (2): 5 percent of

active amine photosensitizing accelerator: 6 percent.

The preparation method of example 5 is the same as that of example 2.

Example 6

oligomer: 40 percent of

A difunctional urethane acrylate oligomer having a molecular weight of 2800;

monomer (b): 46 percent

25% trimethylolpropane triacrylate, 15% tripropylene glycol diacrylate, 6% 1, 6-hexanediol diacrylate;

leveling agent: 3 percent of

Cellulose acetate butyrate;

photoinitiator (2): 5 percent of

3.5% of 2-hydroxy-methylphenylpropanemethanone, 1.5% of 2, 4, 6-trimethylbenzoyl-diphenylphosphine oxide;

active amine photosensitizing accelerator: 6 percent.

The preparation method of example 6 is the same as that of example 2.

Comparative example 1

oligomer: 38 percent of

Tetrafunctional epoxy acrylate oligomer, molecular weight 3200;

monomer (b): 49 percent of

15% trimethylolpropane triacrylate, 34% tripropylene glycol diacrylate;

leveling agent: 3 percent of

Cellulose acetate butyrate;

photoinitiator (2): 5 percent of

2% of 2-hydroxy-methylphenylpropanophenone, 1.5% of 1-hydroxy-cyclohexyl-phenylmethanone, 1.5% of 2, 4, 6-trimethylbenzoyl-diphenylphosphine oxide;

active amine photosensitizing accelerator: 5 percent.

The preparation method of comparative example 1 was the same as that of example 2.

Comparative example 2

oligomer: 40 percent of

A difunctional urethane acrylate oligomer having a molecular weight of 2800;

monomer (b): 46 percent

40% trimethylolpropane formal acrylate and 6%, 1, 6-hexanediol diacrylate;

leveling agent: 3 percent of

Cellulose acetate butyrate;

photoinitiator (2): 6 percent of

4.5% of 2-hydroxy-methylphenylpropane-1-one, 1.5% of 2, 4, 6-trimethylbenzoyl-diphenylphosphine oxide;

active amine photosensitizing accelerator: 5 percent.

Comparative example 3

oligomer: 40 percent of

A difunctional urethane acrylate oligomer having a molecular weight of 2800;

monomer (b): 42 percent of

35% trimethylolpropane triacrylate, 7% tripropylene glycol diacrylate;

leveling agent 3%

An organosilicon;

photoinitiator (2): 5 percent of

active amine photosensitizing accelerator: 10 percent.

The preparation method of comparative example 3 is the same as that of example 2.

Test examples

By adopting a flexography method, the gloss oil of example 1 is transferred to a flexographic printing plate by a 350-mesh anilox roller, and then the gloss oil on the flexographic printing plate is transferred to the surface of a PET substrate under the pressure of an impression cylinder to form a paint film, wherein the thickness of the paint film is 1-3 mu m.

The paint films required for examples 2 to 6 and comparative examples 1 to 3 were obtained in the same manner, and the obtained paint films were subjected to the following tests, the results of which are shown in Table 2.

Curing test

The method comprises the following steps of (1) testing by a dry method (indentation method): placing the PET substrate with the paint film on an ultraviolet lamp curing machine for curing, slightly pressing the paint film with fingers, and judging the paint film to be qualified if no fingerprint trace exists on the surface of the paint film; otherwise, the test piece is regarded as not-qualified.

Recoat test

Printing color ink on the PET substrate with the paint film through a flexo printing proofing machine to form a color ink pattern, and if the color ink pattern is clear and has no shrinkage cavity, judging the color ink pattern to be qualified; otherwise, the test piece is regarded as not-qualified.

Release test

Detecting the peeling force of a paint film peeled from a PET substrate with the width of 25mm by using a peeling strength tester, and if the peeling force is within 0.6-4N/cm, judging that the release effect is qualified; otherwise, the release effect is determined to be unqualified.

Aging test

Placing the paint film in an environment with the temperature of 80 ℃ and the humidity of 80% for 24h for accelerated aging, taking out after 24h, drying, and carrying out a release test, wherein if the adhesive tape can completely peel off the paint film on the PET substrate and the surface of the substrate has no residual paint film, the paint film is qualified; otherwise, the test piece is regarded as not-qualified.

Solid content test

The tests were carried out according to GB 1725-1979.

TABLE 1

As can be seen from Table 1, although the UV gloss oil of the examples and the comparative examples has high solid content, i.e. the environmental pollution caused by volatile organic compounds can be avoided, the high-functionality oligomer is adopted in the comparative example 1, and the release effect and the recoating effect of the formed paint film are difficult to meet the requirements compared with the gloss oil of the example 1; by using the monomer other than the embodiment of the present invention in comparative example 2, the release effect of the varnish-formed paint film was poor compared to examples 1 to 6. Compared with examples 1-6, the leveling agent adopted in the comparative example 3 has the advantages that the cellulose acetate can not only play a leveling effect, but also further improve the release effect after the varnish film is formed by the varnish.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The UV gloss oil is characterized by comprising the following raw materials in percentage by weight:

oligomer, 25-50%;

39-60% of monomer;

5-8% of a leveling agent;

3-6% of photoinitiator;

2. The UV varnish according to claim 1, wherein the oligomer is selected from one or both of urethane acrylate oligomer and epoxy acrylate oligomer.

3. The UV varnish of claim 1, wherein the oligomer has a molecular weight of 2200 to 4100.

4. The UV varnish according to claim 1 or 2, wherein the cellulose acetate leveling agent is selected from cellulose acetate butyrate.

5. The UV varnish according to claim 1, wherein the photoinitiator is selected from one or more of 1-hydroxy-cyclohexyl-phenyl-methanone, 2-hydroxy-methylphenyl propane-1-one, and 2, 4, 6-trimethylbenzoyl-diphenyl phosphine oxide.

6. The UV gloss oil of claim 1, wherein the raw materials of the UV gloss oil further comprise:

2-10% of active amine photosensitive promoter.

7. The UV gloss oil of claim 1, wherein the UV gloss oil is prepared by respectively dissolving a photoinitiator and a leveling agent by using a monomer and then mixing.

8. The method of preparing the UV varnish of any one of claims 1 to 7, wherein the method comprises the steps of:

9. The method of claim 8, wherein a reactive amine light sensitive promoter is added to the mixture of mixture a, the oligomer, mixture B and the balance of the monomers.

10. The method of using the UV varnish according to any one of claims 1 to 7, wherein the UV varnish is printed on the surface of a substrate and cured to form a varnish film; preferably, the printing is flexographic printing.