RU2395827C2 - Liquid photopolymerised composition for laser stereolithography - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: proposed composition comprises meta-acrylic oligomers and initiating system. Said meta-acrylic oligomers represent a mix of multifunctional meta-acrylic derivatives of hydroxyl-containing oligo-ether(meta)-acrylates, while photoinitiator comprises compounds from the group of α-hydroxy ketones, α-amino ketones, α-di-ketones, aryl-alkil ketals, alkoxy aryal alkyl phosphine oxides.

EFFECT: higher efficiency of laser stereolithography units.

4 cl, 3 dwg, 1 tbl, 11 ex

Description

The invention relates to liquid photopolymerizable compositions (FPK) for use in technologies for the rapid manufacture of prototype models (rapid prototyping), especially by laser stereolithography (LSL).

Known liquid FPK have a typical composition:

- photopolymerizable resin containing reactive oligomers and (or) monomers;

- photoinitiating system containing photoinitiators and activators of their decomposition (reducing agents);

- additives, including inert and active fillers, regulators, stabilizers, inhibitors, plasticizers, etc.

Suitable reactive oligomers and monomers are:

- compounds with unsaturated carbon-carbon bonds in the molecule, most often vinyl and (meth) acrylic;

- heterocyclic compounds with strained cycles, often epoxy.

Depending on the type of reactive groups and the source of radiation, a photoinitiating system is selected - radical or ionic, usually cationic.

The introduction of various additives into liquid FPKs makes it possible to obtain polymers with a certain set of properties — physicochemical, biological, etc.

From the point of view of photoinitiation efficiency, energy consumption and the influence of various factors on the initiation process, radical photoinitiators with minimal use of sensitizers, activators, chain transfer agents, etc. are the winning ones. The energy of a quantum of light in the range of 240-410 nm is enough to break the chemical bond in the molecule and form a pair of free radicals. The use of radiation sources in this range seems to be fundamental. In contrast, compositions that polymerize in the visible range with wavelengths above 410 nm should have a very high threshold polymerization energy to avoid unwanted spontaneous polymerization from ambient light. Such compositions are not suitable for work, especially for such operational technology as LSD.

According to the radical mechanism, polymerization of vinyl and (meth) acrylic compounds occurs. In this case, (meth) acrylic compounds in comparison with vinyl have significantly higher speeds and degree of polymerization.

Known compositions that are a mixture of acrylic and epoxy oligomers and, accordingly, two different types of photoinitiating systems. The curing energy of such compositions is determined by a more energy-intensive component.

Conventional FPKs are not designed for LSL technology. Formulations according to the following patents of Russia may be considered suitable for the LSL FPK: RU 2244335, RU 2269416, RU 2127444; USA: US 7211368, US 7232850; international application WO 2006107759. All of the claimed compositions have a number of limitations and disadvantages when used in modern LSL installations.

Russian patent No. 2127444 describes a composition based on OKM-2 oligocarbonate dimethacrylate and TGM-3 triethylene glycol dimethacrylate. Both monomers have a large shrinkage during polymerization, a low polymerization rate and insufficient viscosity for a number of applications. As a result of using such a FPK, it is not possible to observe the necessary dimensional accuracy and the required operational characteristics of the manufactured model.

US patent No. 7232850 describes a number of compositions for laser stereolithography, which in addition to acrylic oligomers and radical photoinitiators also contain epoxy oligomers and, accordingly, cationic photoinitiators. The claimed FPKs allow to obtain accurate prototypes with good physicochemical characteristics, but they are not optimal in terms of performance and are limited in application. Most models manufactured using LSL technology have priority in manufacturing efficiency, for example, models of biological objects created using computed tomography data.

US patent No. 7211368 and international application No. 2006107759 describe a class of photopolymerizable compositions containing acrylic oligomers with urethane groups in an oligomeric block and other (meth) acrylates as a base. The compositions provide the ability to obtain certain physical and mechanical characteristics of the final stereolithographic models. However, the use of urethane compositions makes it possible to obtain mainly flexible models, while often the stereolithographic model must have a certain rigidity. Flexible prototypes are inconvenient for cases when prototypes are used in conjunction with parts made of structural materials, such as metal, substantially harder than the urethane prototype, and capable of causing undesirable deformation of a malleable plastic part.

Closest to the proposed composition is a photopolymerizable composition for lithography using visible light, including acrylic oligomers, as it contains hexanediol diacrylate or trimethylolpropane triacrylate and ethoxylated diphenylolpropane diacrylate and a initiating system - a mixture of Bengal rose with dimethyl-ethanol-2-ethanol 2 pyrrolidone (RF Patent No. 224335, MKI ⁷ G03F 7/004, C08F 291/06, 2002). Additionally, the composition may contain polymethylmethacrylate (PMMA). Despite the claimed FPK, cured by radiation of the visible range of the spectrum, i.e. ~ 380-780 nm, in fact, the FPK of monochrome radiation of the “green” spectral region with a wavelength of 532 nm was proposed. There are no such industrial stereolithographic installations on the market. The creation of industrial plants for LSL with a working radiation range above 530 nm will require special light protection measures: cameras or rooms that are opaque to visible light, devices for filling the installations, and for storage and transportation of FPK. This can significantly increase the cost of such installations.

The FPK declared in the prototype is distinguished by a new photoinitiating system, which works exclusively in the "green" region of the spectrum. The curing characteristics presented in the application do not satisfy the requirements for modern FPK for LSD. In comparative example 11 of patent No. 224335, the results of the curing of the known UV-based FPK based on oligoester methacrylate MDF-2 and the combined Darocur 4265 photoinitiator, which without any additives offer the best characteristics of all those given in the application, are shown. Meanwhile, the FPK indicated in Example 11 is practically not used in modern LSL installations due to low operational characteristics (low speed and degree of polymerization, low sensitivity to radiation, high shrinkage, strength and sanitary characteristics unsatisfactory for a number of applications). Effective photoinitiators for the polymerization of FPK by radiation in the range of 380-410 nm (visible blue light) are currently available. Their cost is comparable to traditional UV photoinitiators.

The composition of the polymerization-capable oligomers and low viscosity diluents claimed in patent No. 2244335 is typical for the LSL of the UV range, and when using the appropriate photoinitiating system, such a FPK can satisfy the requirements of a number of industries using this technology. However, due to the fact that the claimed composition contains exclusively acrylic (and not methacrylic) derivatives, it cannot be applicable, for example, in the manufacture of biomedical products. All declared polymerizable components of FPK: hexanediol diacrylate or trimethylolpropane triacrylate and diphenylolpropane ethoxylated diacrylate are classified as moderately hazardous compounds (hazard class 3 according to GOST 12.1.007). Similar methacrylates belong to low-hazard compounds (hazard class 4 according to GOST 12.1.007). In addition, methacrylic analogues of the claimed composition have a lower viscosity and higher strength characteristics of the polymerizates. In the description of patent No. 224335, the main oligomer - ethoxylated diphenylol propane diacrylate - is erroneously called the abbreviation of the well-known oligomer "Bis-GMA" and the structural formula corresponding to "Bis-GMA" is given, and not the declared ethoxylated diphenylol propane diacrylate. It is also known that the Bis-GMA oligomer is not an individual compound of constant composition, but consists of a mixture of 3 main isomers, the type and ratio of which depends on the preparation method. For example, “Bis-GMA”, obtained by the interaction of methacrylic acid with bisphenol-A and obtained by the interaction of glycidyl methacrylate (GMA) with bisphenol-A, have 2 completely different in structure, ratio and properties of the isomeric product (Surovtsev MA Synthesis derivatives and analogues of glycidyl methacrylate and their conversion to polymeric sorbents and ion exchangers. Diss. Candidate of Chemical Sciences. - Yaroslavl, 2001. - 180 p.). Accordingly, the uncured oligomer Bis-GMA synthesized from various starting components and the products of its polymerization have different physicochemical and operational characteristics. This explains the variety of brands and properties of oligomers, united by the common abbreviation "Bis-GMA".

The present invention is the creation of a storage stable liquid photopolymerizable composition, providing high performance operating stereolithographic installations of domestic and foreign production.

The indicated result is achieved by a liquid photopolymerizable composition for laser stereolithography using light radiation containing a photopolymerizable resin comprising (meth) acrylic oligomers, and a photoinitiating system comprising a mixture of radical initiators and reducing agents, which according to the invention contains polyfunctional (meth) acrylic produced hydroxyl-containing compounds selected from the group:

oligomer 1, which is the products of the interactions of glycidyl (meth) acrylate with bisphenols and / or their hydroxyalkyl derivatives of the general formula:

[CH ₂ = C (R) -C (O) O-] _n -Q- (OH) _m and / or [CH ₂ = C (R) -C (O) O-] _n -Q

where R = CH ₃ , H;

n≥2;

m is an integer from 1 to 4;

Q is an arylene or alkyleneoxyarylene organic residue of a polyol (hydroxyl-containing compound from the group of polyhydric alcohols and polyphenols, polyether polyols),

oligomer 2, which is the product of the interactions of glycidyl (meth) acrylate and / or methyl (meth) acrylate and / or (meth) acrylic acid with polyhydric alcohols, polyether polyols of the general formula:

[CH ₂ = C (R) -C (O) O-] _n -Q- (OH) _m and / or [CH ₂ = C (R) -C (O) O-] _n -Q

where R = CH ₃ , H;

n≥2;

m is an integer from 1 to 5;

Q is an alkylene or cycloalkylene organic residue of a polyol (hydroxyl-containing compound from the group of polyhydric alcohols, heteropolyols, polyether polyols),

oligomer 3, which is the product of the interactions of glycidyl (meth) acrylate and / or methyl (meth) acrylate and / or (meth) acrylic acid with di- and polycarboxylic acids, their esters or anhydrides of the general formula:

[CH ₂ = C (R) -C (O) O-] _n -Q- (OH) _m and / or [CH ₂ = C (R) -C (O) O-] _n -Q

where R = CH ₃ , H;

n≥2;

m is an integer from 1 to 5;

Q is an alkylene, arylene or alkylene arylene organic residue of a polyol (a hydroxyl-containing compound from the group of polyhydric alcohols, polyphenols, simple and complex polyether polyols, di- and polycarboxylic acids, their esters or anhydrides);

or mixtures thereof in the following ratio of the main parts:

photopolymerizable resin 90-99% photoinitiation system 1-10%

Preferably, as the (meth) acrylic derivative, the liquid photopolymerizable composition comprises glycidyl derivatives of (meth) acrylate and / or methyl (meth) acrylate or (meth) acrylic acid.

Preferably, as a reducing agent for the radical photoinitiators of the initiating system, the liquid photopolymerizable composition contains monomers with tertiary amine groups or mixtures thereof.

Preferably, as the monomeric reducing agent, the liquid photopolymerizable composition comprises alkyl (aryl) aminoalkyl (meth) acrylates.

Preferably, as a radical photoinitiator, the liquid photopolymerizable composition contains compounds from the groups of α-hydroxyketones, α-aminoketones, α-diketones, arylalkyl ketals, alkoxy arylalkylphosphine oxides and mixtures thereof having light absorption maximums in the region of 240-410 nm.

Possible ways of synthesizing polyfunctional (meth) acrylic derivatives of hydroxyl-containing compounds are:

1. addition of GMA to the polyol under conditions of alkaline catalysis or (meth) acrylic acid with polyglycidyl ethers of polyphenols (Surovtsev MA Synthesis of derivatives and analogues of glycidyl methacrylate and their conversion into polymer sorbents and ion exchangers. Diss. Candidate of Chemical Sciences. - Yaroslavl , 2001. - 180 p.: Pp. 11-16, 41-58, 131-132);

2. transesterification of GMA and / or MMA with a polyol (Surovtsev MA Synthesis of derivatives and analogues of glycidyl methacrylate and their conversion into polymer sorbents and ion exchangers. Diss. Candidate of Chemical Sciences. - Yaroslavl, 2001. - 180 p .: p.19 -21, 68-74, 132-136);

3. esterification of MAA with a polyol (described in: Surovtsev MA Synthesis of derivatives and analogues of glycidyl methacrylate and their conversion into polymeric sorbents and ion exchangers. Diss. Candidate of Chemical Sciences. - Yaroslavl, 2001. - 180 pp .: p.11- 16, 41-58, 133-135);

4. condensation telomerization (described in: Berlin A.A., Korolev G.V., Kefeli T.Ya. - Acrylic oligomers and materials based on them. M: Chemistry, 1983, 232 pp.: 13-46 ;

Berlin A.A., Kefeli T.Ya., Korolev G.V. Polyester acrylates. M .: Nauka, 1967, 372 p.: P. 37-77) and other well-known methods (described in: Chemical Encyclopedia, vol. 3, M .: BRE, 1992, p. 744-746; Alfred Anisimovich Berlin. Selected Proceedings, Memoirs of Contemporaries, Moscow: Nauka, 2002 .-- 362 pp., pp. 15-17).

For example, the ways of synthesis of storage-stable and highly sensitive to photopolymerization polyfunctional (meth) acrylic derivatives of hydroxyl-containing compounds are the following interactions:

- glycidyl (meth) acrylate with bisphenols and / or their alkoxylated derivatives;

- glycidyl (meth) acrylate and / or methyl (meth) acrylate with polyhydric alcohols, polyether polyols and their alkoxylated derivatives;

- glycidyl (meth) acrylate, and / or methyl (meth) acrylate, and / or (meth) acrylic acid with di- and polycarboxylic acids, their esters or anhydrides.

Specific examples of the above multifunctional (meth) acrylic derivatives of hydroxyl-containing compounds include the following main types of polymerization oligomers:

Oligomer 1

where X = C (CH ₃ ) ₂ ; S (O) ₂ ; ABOUT; C (O); C (CF ₃ ) ₂

Oligomer 2

Oligomer 3

where MA — CH ₂ = C (R) —C (O) -; R-CH ₃ , H; l≥1

It should be noted that all of the above multifunctional (meth) acrylic derivatives of hydroxyl-containing compounds obtained by the above methods are mixtures of oligomers, the main components of which are represented by the above structural formulas.

The photopolymerizable composition may additionally contain inert and reactive compounds (additives) for the correction of physical and technical characteristics, including active diluents of photopolymerizable resins (low viscosity monomers and oligomers), plasticizers, inhibitors, stabilizers and other modifiers. The polymerization (active) diluents may be any known monomers without particular limitation. Preferred active diluents are low viscosity (meth) acrylates with at least two reactive groups in the molecule: low viscosity oligourethane (meth) acrylates, oligocarbonate (meth) acrylates, oligopolyether (meth) acrylates. A number of active diluents can simultaneously serve as internal plasticizers and shrink modifiers. More preferred active diluents are GMA and low viscosity derivatives of GMA (and / or MMA) and polyhydric alcohols, polyphenols, polyether polyols, polycarboxylic acids, their esters or anhydrides.

As a photoinitiating system, the composition contains a mixture of one or more radical photoinitiators and one or more monomeric reducing agents (activators).

Preferred photoinitiators are derivatives of benzoin, phenons, quinones, phosphine oxides having light absorption maximums in the region of 240-410 nm.

More preferred photoinitiators are compounds from the following groups: α-hydroxyketones, α-diketones, α-aminoketones, alkoxyarylalkylphosphine oxides, arylalkyl ketals, and mixtures thereof.

In contrast to the prototype, the claimed FPK as reducing agents (activators) of radical photoinitiators of the initiating system contains monomers with groups of tertiary amines or mixtures thereof, which allows them to participate in the (co) polymerization reaction and not migrate from the cured products, worsening their sanitary and operational characteristics. Preferred monomeric reducing agents are alkyl (aryl) aminoalkyl (meth) acrylates selected from the group of reaction products of GMA and / or MMA with alkyl (aryl) aminoalkanols. More preferred monomeric reducing agents are dimethyl and / or diethylaminoethyl methacrylate, morpholinoethyl and / or morpholinohydroxypropyl methacrylate, triethanolamine trimethacrylate, and mixtures thereof.

The inventive composition allows the manufacture of three-dimensional products using laser stereolithography technology using a UV laser or other light radiation source with a wavelength of not higher than 410 nm. For the case of using a HeCd laser (wavelength λ = 325 nm), the characteristics are determined that make it possible to obtain films of a fixed thickness at a fixed exposure dose of UV radiation (see the absorption spectrum of the proposed FPK in Fig. 1). For other radiation sources, such characteristics can be determined experimentally.

The invention is illustrated by the following examples.

Example 1

A photopolymerizable resin was prepared by mixing: oligomer 1 — the reaction product of GMA with isopropylidene-bis- (hydroxybenzene) 20 parts by weight, oligomer 1 — the reaction product of MAA with isopropylidene-bis- (oxiranylmethyloxybenzene) 20 parts by weight, oligomer 2 — product the interaction of GMA and / or MAK with 1,3-dihydroxy-2,2- (dihydroxymethyl) propane 20 parts by weight, oligomer 3 - the product of the interaction of MMA with dihydroxy-triethylene dioxide 30 parts by weight obtained by known methods was added photoinitiating system consisting of: bis- (dimethoxybenzoyl) trimeth phenyl-phosphine oxide 1 part by weight of 2-hydroxy-2-methylpropiophenone 3 parts by weight, 1 part by weight morfolinoetilmetakrilata and additives (viscosity regulator or active diluent - GMA, inhibitor - ionol, plasticizer - polyglycol) up to 100 parts by weight

The composition was homogenized by thoroughly mixing the photopolymerizable resin, the photoinitiating system, and additives in a light-proof thermostatic mixing reactor by sequential dosing (loading) and mixing the components at a temperature not exceeding 60 ° C.

Preliminary tests of photopolymerization of FPKs were carried out by irradiating a drop of a composition in the form of a fluoroplastic (diameter 15 mm, thickness 1 mm), placed between two glass slides, with a UV lamp with a power of 120 W / cm at a distance of 100 mm for 1 min. Samples were taken with a dense non-sticky film.

The physicochemical characteristics of polymer samples from FPK that have passed preliminary tests for biomedical purposes were determined according to Clause 6 of GOST R 51202-98.

The storage stability of the obtained FPC was tested by keeping the FPC sample at 45 ° C for 14 days. No gelation and polymerization of FPK was observed. Storage of FPK at 45 ° C for 14 days is equivalent to approximately two-year storage at 4 ° C in the refrigerator, which can be considered as an acceptable storage period for the practical use of FPK.

The performance of the LSL installation using the claimed FPK was evaluated by testing operational characteristics.

Testing the operational characteristics of the composition was carried out on the existing experimental prototype laser stereolithographic installation. The first stage of testing consisted in the manufacture of monolayer films by laser shading on the surface of the FPK sections, representing a circle with a diameter of 1 cm. Several samples were drawn, each with its own exposure dose. At the end of the experiment, the thicknesses of the obtained objects were measured and the sensitometric dependence of the thickness of the obtained films on the exposure dose was constructed. The experimentally obtained dependence (figure 2) is described by the equation:

h = D _p ln (E / E _c ),

where h is the film thickness,

E is the exposure dose,

D _p and E _c are experimentally determined constants characterizing the penetration depth of the initiating radiation into the composition and the threshold value of the exposure dose, respectively.

This dependence is used to determine the exposure dose necessary for curing the film of the required thickness in the process of manufacturing a stereolithographic model with the desired step. Underexposure will not allow to obtain a solid model, overexposure will have a negative impact on manufacturing accuracy. Based on the calculated value of the exposure dose, taking into account the value of the diameter of the laser beam and the current power, the speed of drawing by the laser beam is determined, which allows curing the FPK layer of the required thickness.

Examples of compositions of a liquid photopolymerizable composition for laser stereolithography, tested with positive results, are presented in table 1.

The inventive composition has been successfully tested in laser stereolithographs LS 120, LS 250 and LS 350. Figure 3 shows photographs of products made from the claimed composition, commercially available under the brand name FPK LSL-10-325 according to TU 2216-405-05842324-2005.

Liquid photopolymerizable composition for laser stereolithography Table 1. Examples of the preparation of a liquid photopolymerizable composition for laser stereolithography Component Example No., mass fraction one 2 3 four 5 6 7 8 9 10 eleven Oligomer 1 the product of the interaction of GMA with isopropylidene-bis- (hydroxybenzene) twenty 40 twenty 35 44 the product of the interaction of MAA with isopropylidene-bis- (oxiranylmethyloxybenzene) twenty thirty 10 fifty twenty the product of the interaction of MMA and / or GMA, and / or MAA with isopropylidene-bis- (hydroxyalkylene oxybenzene) 10 5 twenty Oligomer 2 the reaction product of MMA and / or GMA and / or MAA with 1,2- and 1,3-dihydroxy (alkyl) propane or 1,2,3-trihydroxypropane 42 60 10 39 10 the reaction product of GMA and / or MAA with 1,1,1-trihydroxyalkylpropane fifty 95 40 80 10 reaction product of GMA and / or MAA with 1,3-dihydroxy-2,2- (dihydroxymethyl) propane twenty twenty 10 10 reaction product of GMA and / or MAA with 2,2,6,6-tetrahydroxymethyl-cyclohexanol 40 10 Oligomer 3 the product of the interaction of MMA, and / or GMA, and / or MAA with bis- (hydroxypolyalkyleneoxycarboxy) benzene 10 fifteen fifteen fifteen 4,5 the product of the interaction of MMA and / or GMA, and / or MAA with dihydroxyalkane and / or dihydroxy- (polyalkylene polyoxide) thirty 12 5 fifteen Radical photoinitiator bis (dimethoxybenzoyl) trimethylphenylphosphine oxide one one 0.5 2,2-dimethoxy-2-phenylacetophenone four four 0.6 4,5 2-hydroxy-2-methylpropiophenone 3 3 2 1,5 2,3-bornandion 2.5 four Benzyldimethylamino (morpholinophenyl) butanone 5 2 1,5 Monomeric reducing agent Dimethylaminoethyl (meth) acrylate one one 0.4 Diethylaminoethyl (meth) acrylate 2 2 Morpholinoethyl (meth) Acrylate one 2 four Morpholinhydroxypropyl (meth) acrylate 5 Triethanolamine tri (meth) acrylate 2.5 0.5 Additives active diluents, plasticizers, inhibitors, stabilizers and other modifiers up to 100 up to 100 up to 100 up to 100 up to 100 up to 100 up to 100 up to 100 up to 100 up to 100 up to 100

Claims (4)

1. A liquid photopolymerizable composition for laser stereolithography using light radiation, containing a photopolymerizable system based on (meth) acrylic oligomers and a photoinitiation system comprising mixtures of radical initiators and reducing agents, characterized in that the composition contains a mixture of one or more polyfunctional (meth) acrylic derivatives of hydroxyl-containing oligomers of the formula 1, 2 and 3:
Oligomer 1, which is the products of the interactions of glycidyl (meth) acrylate with bisphenols and / or their hydroxyalkyl derivatives of the general formula:
[CH ₂ = C (R) -C (O) O-] _n -Q- (OH) _m and / or [CH ₂ = C (R) -C (O) O-] _n -Q,
where R is CH ₃ , H;
n≥2;
m is an integer from 1 to 4;
Q is the residue of polyhydroxy-containing phenyl or alkyloxyphenyl;
Oligomer 2, which represents the products of the interaction of glycidyl (meth) acrylate and / or methyl (meth) acrylate and / or (meth) acrylic acid with a polyhydric alcohol of the formula:
[CH ₂ = C (R) -C (O) O-] _n -Q- (OH) _m and / or [CH ₂ = C (R) -C (O) O-] _n -Q,
where R is CH ₃ , H;
n≥2;
m is an integer from 1 to 5;
Q is an alkylene or cycloalkylene organic residue of a polyhydroxy-containing compound;
Oligomer 3, which is the product of the interactions of glycidyl (meth) acrylate and / or methyl (meth) acrylate and / or (meth) acrylic acid with di- and polycarboxylic acid, or its ether, or anhydride of the formula:
[CH ₂ = C (R) -C (O) O-] _n -Q- (OH) _m and / or [CH ₂ = C (R) -C (O) O-] _n -Q,
where R is CH ₃ , H;
n≥2;
m is an integer from 1 to 5;
Q is an alkylene or alkylene phenyl residue of a hydroxide-containing compound from the group of polyhydric alcohols, polyphenols, ethers and esters, di- and polycarboxylic acids, their esters or anhydrides;
with a mass ratio of oligomers 1, 2 and 3 equal to 20-55: 20-90: 5-30, respectively, and as a photoinitiating system, a mixture of one or more radical photoinitiators with a monomeric reducing agent of a series of (meth) acrylates containing a tertiary amino group when a mass ratio of 0.6-6.0: 0.4-5.0, respectively, with the following ratio of components of the composition, wt.%:
specified photopolymerizable system 90-99 specified photoinitiation system 1-10 2. The liquid photopolymerizable composition according to claim 1, characterized in that the (meth) acrylic derivative contains a glycidyl derivative (meth) acrylate and / or methyl (meth) acrylate. 3. The liquid photopolymerizable composition according to claim 1, characterized in that it contains alkyl (phenyl) aminoalkyl (meth) acrylates as a monomeric reducing agent. 4. The liquid photopolymerizable composition according to claim 1, characterized in that as a radical photoinitiator it contains compounds from the groups of α-hydroxyketones, α-aminoketones, α-diketones, arylalkyl ketals, alkoxyarylalkylphosphine oxides and mixtures thereof having light absorption maximums in the range of 240- 410 nm.

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