WO2003037936A1

WO2003037936A1 - Visible-light curable composition

Info

Publication number: WO2003037936A1
Application number: PCT/CN2002/000777
Authority: WO
Inventors: Yingwu Yin; Haoya Tan; Wenchao Zhao; Zhenlou Zhong
Original assignee: Insight High Technology Co., Ltd.; Zhuhai Dongcheng Chemical Co. Ltd.
Priority date: 2001-11-02
Filing date: 2002-11-01
Publication date: 2003-05-08
Also published as: CN1415679A

Abstract

The invention relates to a visible-light curable composition comprising: (1) 30-75% by weight of at least one prepolymer containing olefinic unsaturated group; (2) 20-65% by weight of at least one monomer containing olefinic unsaturated group; (3) 0.1-10% by weight of at least one free-radical type photoinitiaor; (4) 0-10% by weight of at least one coinitiator; (5) 0-20% by weight of adjuvants; it can not only substitute for present available ultraviolet-light curable products, and can further widely used in furniture coating as well as large-area indoor and outdoor building coating, and can make it very easy for the promotion and application of the photocurable coatings and inks.

Description

Visible light curing composition

Technical field

The invention relates to a composition containing a radical photoinitiator which is cured by irradiation with a visible light source, and the composition can be widely used in furniture coating and large-area indoor and outdoor coating projects. Background technique

The previous UV curing polymerization technology has been applied in many fields, such as printing cover light used on wood, paper, metal and plastic for decoration and protection; used in optical information field for optical fiber, optical disc, electronic circuit board Manufacturing, etc. However, there are two disadvantages to ultraviolet rays: First, short-wave rays are harmful to the human body, and they need to be well shielded during use. In particular, ultraviolet rays in the 200-315nm band have a fast effect. Inadvertent contact can cause skin redness, inflammation, and corneal burns. Sometimes short-term blindness occurs. The second is that the ozone produced by the ultraviolet rays can cause headaches, fatigue, irritation to the eyes and lungs, and certain harm to operators in this environment for a long time. These problems have limited the application and development of UV-curable polymerization technology to a wider range to some extent. The visible light curing composition does not contain short-wave ultraviolet rays in the light source, does not generate ozone, has no burn effect on the skin, and is easy to use and operate safely. The movable light source can be applied to a larger area and can be used in places where people are active; Visible light has a long wavelength and strong penetrating power, which is more favorable for curing the underlying layer.

Therefore, people have been trying to research and develop compositions that can be cured by visible light. For example, US6106999 discloses a visible light curable resin composition in which an organic boron compound is used as a photoinitiator and Ar or YAG laser vibration light is used as a light source; JP10-17604A discloses a visible light sensitive resin composition in which titanium is used. Compounds and coumarin compounds as photoinitiators; US6110987 discloses a photocurable composition using a quaternary boron salt and a radical ultraviolet photopolymerization initiator; US5368990A discloses a photocurable composition containing a diaryl Iodine compounds act as polymerization initiators. These visible light-initiated cations are examples of curing of photoinitiators. The initiators are expensive and difficult to promote. In addition, CN1215421A discloses a visible light polymerizable composition containing a combination of a polythiol and an acylphosphine oxide initiator. The storage period of the composition is only about one week, which is very inconvenient to use.

Therefore, there is a need for a visible light curing composition that combines the advantages of low cost, good stability, fast curing, and the like with the safety and visible penetration of visible light. The present invention satisfies the above requirements by providing a visible light curing composition as described in detail below. Disclosure of invention

The invention provides a composition containing a photoinitiator which is cured by irradiation with a visible light source, which can replace the existing ultraviolet curing products, and can be widely used in large-area indoor and outdoor coating projects.

The present invention provides such a visible light curable composition, which includes:

(1) 30 to 75% by weight of at least one prepolymer containing ethylenically unsaturated groups;

(2) 20 to 65% by weight of at least one monomer containing an ethylenically unsaturated group;

(3) at least one free radical photoinitiator from 0.1 to 10% by weight;

(4) 0-10% by weight of at least one co-initiator;

(5) 0-20% additive by weight.

In a preferred embodiment, the radical type photoinitiator of component (3) and component (4) is combined with a co-initiator.

The visible light-curable composition of the present invention containing an ethylenically unsaturated group-containing prepolymer and a monomer is a substance capable of polymerizing and curing under radical initiation. Suitable such prepolymers and monomers are well known in the art.

Examples of the component (1) prepolymer include polyurethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, or polyether (meth) acrylate.

Examples of the urethane (meth) acrylate include a reaction product prepared by reacting a hydroxyl group-containing (meth) acrylate with a reaction product of a polyol and an organic polyisochlorate. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, butylene glycol and the like. Examples of the organic polyisocyanate include toluene diisocyanate, 4, 4'-diphenylmethane diisocyanate, 4, 4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Examples of the hydroxyl-containing (meth) acrylate include hydroxymethyl (meth) acrylate, such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. —

The polyester (meth) acrylate prepolymer includes a dehydration condensation product of a polyester polyol and (meth) acrylic acid. Examples of polyester polyols include reaction products of polyols and dibasic acids, where the polyols are, for example, ethylene glycol, polyethylene glycol, cyclohexanedimethyl alcohol, 3-methyl-1,5-pentanediol , C Glycols, polypropylene glycols, 1,6-hexanediol and trimethylolpropane or their alkylene oxide addition products, dibasic acids such as adipic acid, succinic acid, phthalic acid, hexahydrophthalic acid, And terephthalic acid, or its anhydride.

Epoxy acrylates are addition products of the reaction of epoxy resins with unsaturated carboxylic acids such as (meth) acrylic acid, including epoxy (meth) acrylates, phenols, or cresols of bisphenol A type epoxy resins. Epoxy (meth) acrylates of type phenolic epoxy resins, and (meth) acrylates of polyethers such as diglycidyl ether.

Examples of polyether (meth) acrylates include polyalkylene glycol di (meth) acrylates such as polyethylene glycol di (meth) acrylate and polypropylene glycol di (meth) acrylate, and their oxidation Olefin modified product.

The component (2) monomer includes styrenes, (meth) acrylates, vinyl ethers, and the like, and mixtures thereof.

Examples of styrenes and their derivatives include styrene, α-methylstyrene, and the like. (Meth) acrylates include hydroxyalkyl (meth) acrylates, such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; (meth) acrylic acid Fluorenyl esters, such as butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate; alicyclic fluorenyl (meth) acrylates, such as (methyl Cyclohexyl acrylate; Substituted aryl (meth) acrylates, such as benzyl (meth) acrylate; Alkoxy (meth) acrylates, such as 2-methoxy, (meth) acrylate Ethyl ester and 2-ethoxyethyl (meth) acrylate; isobornenyl (meth) acrylate; and (meth) acrylates containing alkoxysilyl groups. Acrylates of phenols, such as phenoxyethyl (meth) acrylate, and nucleophilic substitution products of their halogens; mono (meth) acrylates of glycols, such as mono (methyl) of ethylene glycol ) Acrylate, mono (meth) acrylate of methoxyethylene glycol, mono (meth) acrylate of tetraethylene glycol, and mono (meth) acrylate of triethylene glycol

(Meth) acrylates; examples of useful monomers containing two or more ethylenically unsaturated groups include alkylene glycol di (meth) acrylates, such as ethylene glycol di (meth) acrylate Esters and propylene glycol di (meth) acrylates; low molecular weight polyalkylene glycol di (meth) acrylates, such as diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, Dipropylene glycol di (meth) acrylate and tripropylene glycol di (meth) acrylate, and products thereof modified by alkylene oxide; polyol poly (meth) acrylate, such as trimethylolpropane tri (methyl) Acrylate, pentaerythritol di or tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, trimethylolpropane Tetrakis (meth) acrylate, dipentaerythritol penta- or hexa (meth) acrylate, 1,6-hexanediol diacrylate and its alkylene oxide modified products; and isocyanuric acid alkylene oxide modified products Di- or tris (meth) acrylate.

Examples of vinyl ethers include cyclohexanedimethyl alcohol divinyl ether, hydroxyethyl vinyl ether, and triethylene glycol divinyl ether.

Examples of other monomers include N-vinylpyrrolidone, N-vinylcaprolactam, acrylmorpholine, N-vinylformamide and N-vinylacetamide.

A composition containing an ethylenically unsaturated group-containing monomer may be added to the composition of the present invention to adjust the adhesiveness and flexibility of the cured film. Examples of these useful monomer compounds include hydroxyalkyl (meth) acrylates, such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; ethylene oxide of phenol (Meth) acrylates of alkane adducts, such as phenoxyethyl (meth) acrylate; mono (meth) acrylates of glycols, such as ethylene glycol mono (meth) acrylate, 'methoxy Ethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate; and N-vinyl compounds such as N vinylpyrrolidone and N-ethylene Based on caprolactam.

Polyol poly (meth) acrylates such as difunctional 1, 6-hexanediol diacrylate and trifunctional trimethylolpropane triacrylate are preferably used. 1,6-Hexanediol diacrylate is a straight-chain structure that gives good flexibility to the coating film. Trimethylolpropane triacrylate contains 3 double bonds, which can increase the curing speed of the coating film.

The free radical photoinitiator in the component (3) is a type of compound capable of photochemical reaction and generating free radicals or hydrogen ions upon receiving light. Free radicals generated by free-radical photoinitiators can cause radical polymerization of the system to cure. Photoinitiators with different structures have different absorption spectra and free radical activities. Selecting a photoinitiator that matches the light source's spectral energy distribution will greatly increase the curing speed. When designing a product formula that determines the use and method of use, screening photoinitiators and different photoinitiator combinations may produce synergistic effects from various aspects such as the light source used, curing time requirements, film performance requirements, and economics. Some initiators are Some that are resistant to light aging will yellow and smell, which must be avoided for products with special requirements such as white inks, food packaging adhesives and printing inks.

Examples of photoinitiators include benzoin and its fluorenyl ethers, such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenones, such as acetophenone Ketone, 2, 2-di Methoxy-2-phenylacetophenone (BDK), 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxyacetophenone, 1 -Hydroxycyclohexylphenyl ketone (184), 2-hydroxy-2-methyl-1 -phenylpropan-1-one (1173), 1- (4-isopropylphenyl) -2-hydroxy-2 -Methylpropan-1-one (1116), 1-[4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methylpropan-1-one (2959), 2-methyl -1- [4- (methylmercapto) phenyl] -2-morpholinyl-propane-1-one (907) and 2-benzyl-2-dimethylamino- 1- (4-morpholinyl Phenyl) -butan-1-one (369); anthraquinones, such as 2-tert-butylanthraquinone, 1-chloroanthraquinone, and 2-pentylanthraquinone; thioxanthone, such as 2,4-dimethyl Thiothanone (DMTX), 2, 4-diethylthioxanthone (DETX), 2 (or 4)-isopropylthioxanthone (ITX), 2-chlorothioxanthone (CTX), and 2, 4 -Diisopropylthioxanthone; ketals, such as acetophenone dimethyl ketal, and acetoyl dimethyl ketals; benzophenones, such as benzophenone and 4-benzoyl-4 ' -Methyldiphenyl sulfide (DMS); and glutanone; acylphosphine oxide compounds such as 2, 4, 6-trimethylbenzoyl diphenyl Phosphine oxide (TP0), bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide (819), bis (2, 6-dimethylbenzoyl) -2, 4, 4- Trimethylpentylphosphine oxide (BAP0), 2, 4, 6-trimethylbenzoylphenylethoxyphosphine oxide (TP0-L).

For transparent varnish systems, the amount of the above-mentioned photoinitiator or mixture added is preferably 5 parts or less, more preferably 2-3 parts or less, based on 100 parts of the visible light curing composition.

For colored systems, the amount of photoinitiator added is preferably from 0.1 to 10 parts, more preferably from 2 to 8 parts or less, based on 100 parts of the composition. 'These photoinitiators can be used in combination with co-initiators such as amines and dimethylaminobenzoates. Dimethylaminobenzoates, such as ethyl-p- (dimethylamino) benzoate (EDAB), octyl-p- (dimethylamino) benzoate (0DAB); fluorenyl hydroxyl Ethylamines, for example: triethanolamine, triisopropanolamine, methyldiethanolamine; amine-modified acrylate monomers or prepolymers. It is well known that the co-initiator has a good promotion effect on the hydrogen-initiating initiator, and at the same time, it has the effect of overcoming the inhibition of oxygen by radical polymerization.

The amount of the co-initiator added is preferably 0.1 to 10 parts or less, more preferably 0.5 to 5 parts based on 100 parts of the photocurable composition.

In addition to the above-mentioned essential components (1) to (3), an auxiliary component (4) may be included.

The auxiliary component (4) is, for example, a pigment is an essential component for manufacturing an ink, and all pigments suitable for manufacturing an ink can be used in the present invention. Colors other than the basic colors of white, black, red, yellow, and blue You can directly choose the appropriate pigment or mix the basic colors to achieve the color requirements. begging. When the particle size of the selected pigment fails to meet the requirements, the particle size can be further reduced by the grinding equipment to meet the requirements for use.

The pigment is selected in consideration of its adverse effect on curing speed, and storage stability is also a serious issue.

Suitable black pigments can be carbon black; examples of white pigments are titanium dioxide; blue pigments can be phthalocyanine blue; yellow pigments can be benzidine yellow; red pigments can be naphthol red, rissol red, and the like. The amount of each pigment is preferably from 2 to 20%, more preferably from 3-15%.

Sometimes fillers can be added as additives, such as: barium sulfate, silica, talc, clay, and calcium carbonate, which can effectively reduce the cost of ink or impart other properties.

Another special filler is a nano material that can improve toughness and wear resistance. It will be effective in special requirements, although it will increase the cost of the product.

Depending on the products used, the additives can also be other types of additives. For example, in order to further improve product stability and cured film durability, one or more polymerization inhibitors and durability improvers may be added. Examples of polymerization inhibitors are hydroquinone, hydroquinone monomethyl ether, phenothiazine, and N-nitrophenylhydroxylamine aluminum salt, and their addition amount should be based on 10 ppm-2% of the composition. Durability improvers include ultraviolet absorbers, light stabilizers, and antioxidants. 01-5%。 They are preferably added in an amount of 0.01-5%.

Additives such as film-forming aids, thickeners, leveling agents, and defoamers that are effective in ensuring product performance are used in the usual way.

The composition of the present invention can be cured with an ultraviolet light source and a visible light source, and it is more preferable to use a visible light source because it is safer, more reliable, and versatile. If the compositions of the invention are used in outdoor coatings, they can also be cured by sunlight.

The present invention preferably uses a visible light source having a spectral range of 350-780 nm. They include sunlight, fluorescent lamps, metal halide lamps, xenon lamps, and the like. It is preferred to use metal halide lamps, especially krypton lamps and indium lamps, whose spectrum is in the range of 350-650 dishes, and the more effective spectral range is 380-480nm.

The composition of the present invention can be stably stored in a packaging container for more than six months.

The hairpin composition can be applied or brushed on a substrate by a known method. The best way to implement the invention

Examples The following examples and comparative examples can further illustrate the features of the present invention, but are not limited to these examples.

In the embodiment, a 400W torch lamp or an indium lamp is used as a light source, and the distance between the test piece and the filament is 20 cm, but the present invention is not limited thereto.

The comparative example uses a 500W UV lamp as the light source, and the distance between the test piece and the filament is 20cm.

The abbreviations in the examples have the following meanings-

TP0-L: 2, 4, 6-trimethylbenzoylphenylethoxyphosphine oxide (TP0-L) TP0: 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide (TP0)

1173: 2-hydroxy-2-methyl-1 phenylpropan-1-one (1173) 'ITX: 2 (or 4)-isopropylthioxanthone (ITX)

907: 2-methyl-1- [4- (methylmercapto) phenyl]-2-morpholinyl-propane-1-one (907)

184: 1-hydroxycyclohexylphenyl ketone (184)

BDK: 2,2-dimethoxy-2 -phenylacetophenone (BDK)

CN972: Amino acrylate, product of SART0MER

CN120: Epoxy acrylate, product of SART0MER

CN292: Polyester acrylate, product of SART0MER Example 1

Bisphenol A epoxy acrylate 60 parts

Trimethylolpropane triacrylate (TMPTA) 25 parts

Hexylene glycol diacrylate (PE DA) 12. 5 parts

TP0-L 2.5

Triethanolamine 0.85 parts

Curing time 20s Comparative Example 1

The formulation sample of Example 1 was cured for 20 seconds under a UV lamp. Example 2

Bisphenol A epoxy acrylate 60 parts Trimethylolpropane triacrylate (TMPTA) 25 parts Hexylene glycol diacrylate (HDDA) 12. 5 parts

TP0 0.63

1173 1. 90 parts triethanolamine 0.85 part curing time 20s comparative example 2

The formulation sample of Example 2 was cured in a UV lamp for 10 seconds.

CN972 (SART0MER) 9. 6 parts CN120 (SARTOMER) 29 parts CN292 (SARTOMER) 19 parts trimethylolpropane triacrylate (TMPTA) 29 parts hexanediol diacrylate (HDDA) 9. 6 parts ITX 2. 9 parts of triethanolamine 0.96 parts curing time 30s Comparative Example 3

The formulation sample of Example 3 was cured for 30 seconds under a UV lamp. Example 4

CN120 (SARTOMER) 48 parts CN292 (SARTOMER) 19 parts trimethylolpropane triacrylate (TMPTA) 29 parts BDK 2. 9 parts p-dimethylaminobenzoate 0.96 parts Curing time 60s, flexibility 15mm

60. Gloss 131 Hardness 0.67 Comparative Example 4

The formula sample of Example 4 has a curing time of 20s under UV light and a flexibility of 15mm.

60. Gloss 132 Hardness 0.69 Example 5

CN120 (SARTOMER) 48 servings

CN292 (SARTOMER) 19 parts Trimethylolpropane triacrylate (TMPTA) 29 parts

907 2. 9 servings

ITX 0.48 part Triethanolamine 0.96 part Curing time 20s Flexibility 15mm

60 ° gloss 131 hardness ◦ 67 comparative example 5

The sample of the formula of Example 5 has a curing time of 10s under UV light, and has a flexibility of 15mm.

60. Gloss 132 Hardness 0.72 Example 6

CN120 (SARTOMER) 48 servings

CN292 (SARTOMER) 19 parts trimethylolpropane triacrylate (TMPTA) 29 parts Ti02 5 servings

4 TPO

ITX 0.48

907 0. 8 servings

Triethanolamine 0.96 parts

Curing time 20s Comparative example 6

The formulation sample of Example 6 was cured in a UV lamp for 20 seconds.

The amount of the raw materials in the above examples is parts by weight.

Examples 7-12

A total of 8 g of prepolymer and monomer were added to the triethanolamine 0.1 g mixture, and the initiator was applied to the corresponding test panel. After curing, the cured film performance test results were obtained.

Table 2: Photoinitiators, contents and test results of each example

Notes: 1) 1000 is a mixture of 80% (weight) 1173 and 20% 184;

2) 4265 is a mixture of 50% by weight 1173 and 50 TP0.

From the disclosure of the present invention, other embodiments of the present invention will be apparent to those skilled in the art. The description and examples herein are intended as exemplary only, and the true scope and spirit of the invention will be indicated by the claims of the invention. Industrial applicability

The invention provides a visible light curing composition which combines the advantages of low price, good stability, fast curing, etc. of ultraviolet light curing initiator, and the safety of visible light, and good penetrability. It can replace the existing UV curing products, and can be widely used in large area indoor and outdoor coating projects.

Claims

Rights request

1. A visible light curing composition, comprising:

(3) at least one free radical photoinitiator from 0.1 to 10% by weight;

(4) 0-10% by weight of at least one bow booster I;

(5) 0-20% additive by weight.

2. The visible light curing composition according to claim 1, wherein the prepolymer is selected from the group consisting of polyurethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate Or polyether (meth) acrylate.

3. The visible light curing composition according to claim 1, wherein the monomer is selected from the group consisting of styrenes, (meth) acrylates, and vinyl ethers.

4. The visible light-curable composition according to any one of claims 1 to 3, wherein the radical type photoinitiator is selected from:

Substituted benzoyl phosphine oxides; α-hydroxyphenyl ketones; α-aminophenyl ketones; substituted thia anthrones; benzoates; benzoin ethers; benzoyl ketals; or Phenylethylenedione and its derivatives; benzophenones and mixtures thereof.

5. The visible light curing composition according to claim 4, wherein the radical photoinitiator is selected from:

2, 4, 6-trimethylbenzoyldiphenylphosphine oxide, Satoshi 4, 6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethylbenzoyl)- 2, 4, 4-trimethylpentylphosphine oxide, 2, 4, 6-trimethylbenzoylphenylethoxyphosphine oxide; 2, 4, 6-trimethylbenzoylphenylethoxylate Phosphine oxide (TPO-L), methyl phthaloylbenzoate (0MBB), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl]-2-hydroxy-2-methyl Propyl-1-ketone; 2-benzyl-2-dimethylamino- (4-morpholinylphenyl) -butan-; 1-dimethyl, 2-methyl- [4- (ylthio). Phenyl] -2- (4-morpholinyl) -1-acetone; 2-isopropylthioxanthone, 2,4-dichlorothioxanthone (CTX), 2-chloro-1-4 Isopropoxythioxanthone, 2, 4-diethylthioxanthone, 2, 4-dimethylthioxanthone; benzoin and its ethers, benzoyl, benzoin dimethyl ether; or Benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide; or Compounds.

6. The visible light curing composition according to claim 1, wherein the co-initiator is selected from the group consisting of dimethylaminobenzoates, alkylhydroxyethylamines, and amine-modified acrylate monomers or prepolymers

7. The visible light curing composition according to claim 6, wherein:

The dimethylaminobenzoates are selected from ethyl-p- (dimethylamino) benzoate, octyl-p- (dimethylamino) benzoate; the fluorenyl hydroxyl group Ethylamines are selected from triethanolamine, triisopropanolamine or methyldiethanolamine and mixtures thereof; the amine-modified acrylate monomer or prepolymer is selected from diethylamine-modified trihydroxymethyl Propane triacrylate, diethylamine modified ethoxylated trimethylolpropane triacrylate.

8. The visible light curing composition according to claim 6, wherein when the co-initiator is selected from the group consisting of alkylhydroxyethylamines and dimethylaminobenzoates, the added amount is at most 10 wt% of the visible light curing composition It is preferably 0.5 to 5%; when the co-initiator is an amine-modified acrylate monomer or prepolymer, the added amount is at most 30% of the visible light curing composition, and more preferably 10 to 20%.

9. A use of the visible light curing composition according to claims 1 to 8 for curing under the irradiation of a light source in the visible light spectrum of 350-780 nm.

10. The application of the visible light curing composition according to claim 9, wherein the emission spectrum of the visible light source is mainly concentrated in the range of 350-650 nm.

11. The application of the visible light curing composition according to claim 10, wherein the visible light source includes sunlight, a fluorescent lamp, a metal halide lamp, a xenon lamp, and the like, and a krypton lamp or an indium lamp among metal halides is preferably used.

12. A visible light curing composition according to claim 1, which is used for light curing coatings, inks, adhesives, and the like.