CS238663B1 - Photopolymer mixture for silk-screen printing - Google Patents

Abstract

The solution relates to a photopolymer composition, the essence of which is that it contains olefinic ester compounds and polyester resin mixed with photoinitiator pigment, dye, thixotropic agent, flow agent, thermal stabilizer polymerization, plasticizer and active diluent. The composition can be used preferably for hand made by machine screen printing.

Description

The invention relates to photopolymers for screen printing inks.

In the petent literature (US pst. 2453769, US pst. 2453770, US pat. 3013895, US pat. 3051591, US pat. 33226710, US pat. 3511710, US pat. 3772062, US pat. 3804735, US pat. 3759807. US U.S. Pat. No. 3,715,293, U.S. Pat. No. 3673140, U.S. Pat. No. 3528844, U.S. Pat. No. 3700643) discloses solvent-free photopolymer sealants, paints and coatings that can be cured by ultraviolet radiation. These photopolymerizable sealants, paints and coatings are usually a mixture of pigments, carrier polymer resins and unsaturated olefinic high-boiling esters. By adding photoinitiators and photosensitizers, these liquid compositions can be cured at high speed (20 to 30 ms ^-1 ) using UV radiation of appropriate wavelength. The use of photopolymers eliminates the use of volatile solvents, enables energy savings in drying ovens, reduces the degree of oxidation, for example unprotected copper surface due to low curing temperature, saves space and time, reduces labor, provides better work hygiene and environmental protection, more economical production and reducing the proportion of physical labor.

In addition to the high curing speed of the formulated photopolymer composition, it is important to ensure the desired properties of the cured sealant, paint and coating when formulating the composition. These are especially hardness of the curing layer, adhesive properties of the cured layer to the substrate or substrate. and the like, especially for applications where there is an increased thermal and mechanical stress on the cured layer of sealant, paint or coating. Important for screen printing is the question of the viscosity of the formulated composition and its thixotropic properties, which allow good resolution to be obtained while maintaining the smooth surface of larger areas. Otázka Last but not least, the storage stability of the formulated photopolymer blend is also significant, mainly related to the change in viscosity of the athixotropic properties.

In order to obtain the optimum properties of the photopolymer composition for screen printing, it is advantageous if the photopolymer composition contains, in addition to a carrier resin, which in principle allows appropriate viscosity and resulting properties of the cured layer and additives to influence the thixotropic and flow properties of the composition. that occur during storage of the photopolymer composition due to time-dependent physical pigmeit-resin interactions as well as theraic initiated radical reactions.

The photopolymer composition according to the invention fulfills the above-mentioned requirements, characterized in that it contains 20 to 80% by weight of olefinic ester compounds which contain functional groups in their molecule

R.

(CH _{2 •} C - C00) ₂ - R ₂ or (CH _g - C - 000) _{χ r} where χ = 1, 2, 3, 4, ch ₃

R. = H or CM, -, R, = -CH, --C - CH, -,

AND

CH,

-CH ₂ -CH ₂ -CH ₂ -CH ₂ -, -CH ₂ -CH ₂ -CH ₂ -,

- (CH ₂ -CH ₂ -O) _y -CH ₂ -CH ₂ -, where y = 0, 1, 2,

_{-CH2 -CH2} -OH, or R ₃ = CH ₃ -CH ₂ -C? / ^CH 2 ° ^H) 3-z, where z = 1, 2, 3, or C <CH ₂ OH) _{4th x} (CH ₂ O) - (CH ₂ -o);

up to 20% by weight of polyester resins containing 50 mol% of functional groups in their molecule

coocoonebo

ρ.Η

CH- = C-COO-CH-CH-CH-O-

0.05 to 10% by weight of photoinitiator, 5 to 30% by weight of pigment, 0.1 to 5% by weight of dye, 0.05% to 4% by weight of thixotropic agent, 0.05 to 4% by weight of flowing agent, 0.01 to 0.1% by weight of thermal polyaerece stebilizer, 0 to 5% by weight of plasticizer, and 0 to 10% by weight of active diluent containing 3 to 8% by weight of photoinitiator, 40 to 50% by weight of olefinic ester compounds, 10 to 30% by weight of solvent; up to 30% by weight of ether compounds containing functional groups in their molecule

R ₄ -O-CH ₂ -CH ₂ -O-, wherein _{4 4} = CHy, C 1-4 -, ^C 3 ^H 7 or

Ο ^ Η, θ-, β 0.05% by weight of the thermic polymerization stabilizer.

The term polyfunctional olefinic ester compound as used herein refers to esters of N, N-ethylenically unsaturated acids with monofunctional and polyfunctional alcohols, and N, N-ethylenically unsaturated acids can be acrylic acid and methacrylic acid. Typical examples of multifunctional alcohols are ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethlene glycol, tetramethylene glycol, neopentyl glycol, pentaethylene glycol, trimethylolpropane, t-imethylethine, pentaerythritol, dipentaerythritol, and polypentaerythritol.

Typical polyfunctional olefinic ester compounds include, but nevertheless they are curtailed, trimethylpropentriakrylát, trimetb 'lolpropandiakrylát, trimethylolpropantrimethakrylét, trimethylolpropendimethakrylót, neopentyl glycol diacrylate, neopentylglykoldimethekrylát, trimethyloethantriakrylát, triaethylolethantrimethakrylát, tetramethylenglykoldiakrylát, tetramethylenglykoldimethekrylát, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol, diethylene glycol dimethacrylate, triethylene glycol, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate , tetraethylene glycol, pentaerythritdiakrylét, pentaerythritol, pentaerythrittetreakrylát, pentaerythritdimethakrylát, pentaerythrittrlmethakrylát, pentaerythrittetramethakrylát, dipentaerythritdiakrylát, dipen taerythrittriakrylát, dipentaerythrittetraakrylát, dipentaerythritpentakrylát, dipentaeryth.rithexakrylét, dipentaerythritdimethakrylát, dipentaerythritol aerythrittrimethacrylate, dipentaerythrittetraaethacrylate, dipentaerythritpentaaethacrylate, dipentaerythrithexine methacrylate and the like.

The photopolymer composition preferably comprises as photoinitiator benzyl dimethyl ketal or 2-chloro thioxanthone, or a mixture of benzyl dimethyl ketal with mercaptothiazole in a weight ratio of 1: 0.1 to 1: 2. The photopolymer composition as polyester resin preferably contains the reaction product of methecrylic acid epoxy resin with acid number. less than 5 mg KOH per g, optionally the reaction product of phthalic anhydride and 1,2-propylene glycol in a 1: 1 molar ratio with an acid number of 80 to 110 mg KOH per g. The olefinic ester compound contains the photopolymer blend of the invention preferably trimethylol propane triacrylate or a mixture of 2-hydroxyethyl methacrylate with trimethylol propane triacrylate in a weight ratio of 1: 0.9 to 1: 1.1. As a plasticizer, said mixture preferably comprises pentaerythritol tetrekis (1'-mercaptopropionate) or itaconic acid, respectively. The photopolymer composition of the invention may also contain as a photoinitiator a mixture of benzyldimethyl ketal, aercaptobenzthiazole and dimethylaminoethenol in an i: 0.1: 0.1 to 1: 1 ratio by weight,

C.

The term polyester resins useful in the practice of the invention is understood to include the reaction products of phthalic anhydride with polyhydric alcohols, the resulting polyester having an acid number of 80-110 mg KOH / g resin, typical multifunctional alcohols include, but are not limited to, ethylene glycol. , diethylene glycol, triethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, tetramethylene glycol, neopentyl glycol, trimethylolpropane, penta238663 erythritol and the like, or reaction products of epoxy resins with acrylic acid or methacrylic acid with an acid number of <15 mg KOH.

Examples of suitable pigments and dyes for printing inks based on photopolymerizable esters include copper polychlorophthalocyanine blue, copper polychlorophthalocyanine green, copper bromochlorophthalocyanine green, carbon black, iron oxide, chrome yellow, npphtochinone dark red, orange, ruby red, yellow, ruby red light chestnut color, phthalocyanine blue, barium sulphate white, TiOg, PaliofaSt blue, red and others. Pigmented photopolymer inks are produced in a conventional manner for inks, whereby 0.5 to 70% by weight of the pigment is not added to 30 to 95.5% by weight of the photopolymerizable composition.

To accelerate UV curing in the region of 200 to 400 nm, it is necessary to add a photoinitiator to the pigmented and unpigmented photopolymer blend. A typical photoinitiation system comprises the addition of 0.05-10% by weight of benzophenone, benzoin, alkoxybenzoin such as methoxybenzoin, ethoxybenzoin, iso-propoxybenzoin, benzilmethyl ketalem and others. Increased air cure rates can be achieved by using 0.05 to 5% by weight of tertiary amine, especially in conjunction with benzophenone, benzildimethyl ketal, preferably diaethylaminoethanol, methylaminoethanol, mercaptobenzthiazole and 2-halothioxantone.

By thixotropic agent is meant herein substances whose addition in an amount of 0.05 to 4% by weight adjusts such properties of the photopolymer composition in dependence on the shear stress. Typical examples are inorganic natural substances of the bentonite type and activated silica known as Siloxide, Aerosil 200, Aeroail 380 and the like.

The term &quot; flow agent &quot; as used herein refers to flow modifiers and to remove the orange silk screen structure in the area, a typical example being a Modaflow composition having a concentration of 0.05 to 4% by weight.

In order to increase the thermal stability of the photopolymer composition, it is preferred to use a thermal polymerization stabilizer, preferably p-methoxyphenol, at a concentration of 0.005 to 0.5% by weight.

The term emollient herein refers to substances which modify the hardness and flexibility of the resulting cured layer. Typical examples of emollients are phthalic acid esters of alkyl alcohols such as dibutyl phthalate, dioctyl phthalate, trlreeyl phosphate, pentaerythritol tetrakis (n-mercaptopropionate), itaconic acid and the like.

As used herein, the term ether compound refers to the alkyl and ester derivatives of ethylene glycol known as cellosolve acetate, methylcellosolve, ethylcellosolve, propylcellosolve, butylcellosolve, butylcellosolveacetate, ethylcellosolveaetate, methylcellosolveacetate and the like.

As a UV radiation source, a mercury lamp, pulsed mercury lamp, xenon-mercury lamp, arc lamp, deuterium discharge, and the like can be used to cure the photopolymers, paint or coating, i.e. sources that provide intense radiation in the region of 200-400 nm.

Exposure is effected by allowing the photopolymer mixture to be irradiated with a source of UV radiation to dry and cure the ink. In most cases, the UV radiation is between 1.25 and 15 em from the cured substrate. The drying rate when using a 40 W / cm source is less than 30 to 60 s, depending on the intensity and spectral range of the source used. A medium pressure mercury lamp in the range of 180 to 400 nm is preferred. The power of these types of lamps is usually rated at 60 W / c and the lamp surface length ·

The photopolymerizable screen printing compositions of the present invention have a wide range of viscosities, and the addition of an active diluent makes it possible to adjust the viscosity and change the viscosity required during storage and aging. The thixotropic index ranges from up to 6, allowing both manual and machine screen printing. These compositions have improved copper surface adhesion, high heat resistance, and acid resistance.

The invention is illustrated by the following examples.

Example 1

25 ° g of resin A was dissolved in 121.5 g of trimethylolpropanetriacrylate stabilized with 0.06% by weight of p-methoxyphenol at 70 ° C. After this liquid mixture, 10 g of mercaptobenzothiazole, 10 g of benzildimethyl ketal, 5 g of flow agent, 10 g of Aerosil 200, 10 g of dimethylaminoethenol and 100 g of titanium dioxide were added to a three-cylinder laboratory. Showed perfectly homogenized mixture at 20 ° C a viscosity of 33,660 Pa.s at a shear rate of 29.2 s ¹ and 43 975 Pa.s at a shear rate ', 355 ^-1 »compositions was screen-printed on the surface of copper and the laminate in a conventional manner. The screened surface was exposed from a distance of 15 cm using a 200 W mercury medium pressure lamp. The surface reached a pencil hardness of F, H within 30 s exposure, the smoothness of the surface was satisfactory as well as the opacity of the mixture.

Resin A was prepared by reacting 1057.8 g of epoxy resin containing 0.498 g eq. epoxide groups per 100 g resin, viscosity 32.3 Pa.s with 482.6 g methecrylic acid in the presence of 15.4 g triethylbenzylammonium chloride and 0.72 g p-methoxyphenol at 90 ° C. The resulting product showed an acid number of 7.4 mg KOH / 1 g after a reaction time of 8 h and a viscosity of 2.800 Pa.s at 20 ° C. Determination of thermal degradation of the cure of the mixture by thermogravimetric analysis at a heating rate of 10 ° C / 60 s yielded a 1.5% weight loss over a temperature range of 250 to 260 ° C.

Example 2

To the photopolymer blend of Example 1 was added 25 g of active diluent prepared by mixing 50 g of trimethylolpropane triacrylate, 7 g of benzildimethyl ketal, 23 g of white spirit, 20 g of butylcellosolve and 0.05 g of p-methoxyphenol. The diluted photopolymer mixture exhibited a viscosity of 19.600 Pa.s at a shear rate of 29.2 s ¹ and 31.700 Pa.s at a shear rate of 1.355 s ¹ . The surface of the impression of the diluted photopolymer composition under the exposure conditions of Example 1 was perfectly smooth and exhibited pencil hardness F, H.

Example 3

264 g of resin A were dissolved in 116 g of trimethylolpropane triacrylate, stabilized with 0.06% by weight of p-methoxyphenol at 70 ° C. To this liquid mixture was added 2.5 g of mercaptobenzothiazole, 5 g of a flowing agent, 1.5 g of Hostapermgrun 8G green, 2.5 g of bezildimethyl ketal, 10 g of Aerosil 200 and 100 g of Blanc fixe on a 3-cylinder laboratory cylinder. Perfectly homogenized, the mixture exhibited a viscosity of 58,000 Pa.s at shear rate at 20 ° C

-1 * -1 2.92 s and 70.360 Pa.s at a shear rate of 1.355 s. Under the printing and curing conditions of Example 1, the surface was non-sticky in 26 seconds, exhibited satisfactory smoothness, good adhesion to the copper and laminate surfaces and a thermal stress loss of 1.5% by weight of the 250-260 ° C temperature range at 10 ° C heating rate. 60 s.

Example 4

The photopolymer composition of Example 3 was diluted with 35 g of the active diluent of Example 2. The diluted photopolymer composition exhibited a viscosity of 37,000 Pa.s at a shear rate of 29.2 s - and 52,300 Pa.s at a shear rate of 1.355 s. perfectly smooth and exhibit a pencil hardness of F, H. The thermal stress loss of Example 1 was ·5% by weight.

Example 5

750 g of resin A was dissolved in 405 g of trimethylolpropanetriacrylate containing 0.06% by weight of p-methoxyphenol at 70 ° C. 245 g of Blanc fixe, 7.5 g of mercaptobenzothiazole, 25 g of a flow agent, 0 g of Hostepermount 8G green, 7.5 g of benzildimethyl ketal, 30 g of Aerosil 200 and 40 g of pentaerythritetetrais (40 g of pentaerythritethetetris) were added to this liquid mixture on a three-cylinder laboratory. (<-mercaptopropionate). The perfectly homogenized mixture exhibited a viscosity of 43.975 Pe.s at a shear rate of 1.355 s ^-1 and 31.200 Pa.s at a shear rate of 29.2 29.2 s -1. Exposure to the imprint with the conditions of Example t provided a surface with satisfactory smoothness, improved adhesion to the medium surface, and improved flexural flexibility.

Example 6

The photopolymer mixture of Example 5 was diluted with 70 g of the active diluent of Example

2. The diluted photopolymer mixture exhibited a viscosity of 29,300 Pa.s at a shear rate of 1.355 s and 18.450 Pa · s at a shear rate of 29.2 s -1. The surface of the impression was perfectly smooth after exposure according to Example 1 and exhibited pencil hardness F. The thermal stress loss of Example 1 was 1.5% by weight and the surface exhibited increased edhezl at 300 ° C.

Example 7

142 g of resin B were dissolved in a mixture of 88.5 g of trimethylol propane triacrylate and 88.5 g of hydroxyethyl methacrylate containing 0.08% by weight of p-methoxyphenol at 70 ° C. To this liquid mixture was added 143.5 g of Blanc fixe, 13.5 g of itaconic acid, 3 'benzildimethyl ketal, ¹ g of blue pigment Turchesesegnaleluca MCO, 5 g of flowing Sinid ¹ and 10 g of Aerosil 200 on a laboratory triple cylinder. a viscosity of 11.274 1 &quot; s &quot; at a rate of 29.7 s &quot; and 48.854 &quot; s at a shear rate of 1.355 s ^& quot ;. The screening impression was reasonably viscous after exposure to 60 sec under translation conditions 1, exhibited a pencil st F and excellent resistance in the electrolytic bath. Resin B was prepared by polylfondensation of 2 moles of phthalic anhydride and 2 moles of 1,2-propylene glycol in the presence of 0.1% by weight of zinc vinegar. The resulting polyester had an acid number ^r 2 mg KOH / 1 g, a color <12 mg Ig.

Example 8

The photopolymer may of Example 7 was diluted with 12 g of active diluent according to Example 2. The diluted photopolymer composition exhibited a viscosity of 6.700 Pa.s at a shear rate of 29.2 and ^-1 and 42.270 Pa.β at a shear rate of 1.355 s ^-1 . The exposure characteristics of the diluted mixture did not change compared to the undiluted mixture. The cured proof could be stripped mechanically after activation in 1% aqueous KOH at 40 ° C for 60 s.

Claims (10)

Photopolymer first Smee for screen printing characterized in that it contains 20 to 80% by weight of the olefinic ester compounds, which in its molecule functional groups obsehují? 1 _(CH2 = C - C00) ₂ - or Rg _(CH2 = C - COO) * - R 1, where ch ₃ x = 1, 2, 3, 4, R 1 = H or CH 1 -, R 2 _-; = -CHg -C-CHg-, CH, _{-CH2 -CH2} -OH -CH ₂ -CH ₂ -CH ₂ -CH ₂ -, -CH ₂ -CH ₂ -CH ₂ -, - (CH ₂ -CH ₂ -O) _y -CH ₂ -CH ₂ -, wherein y = 0, 1, 2, and R 1 = CH ₃ -CH ₂ -CH ₂ - or (CH ₂ -OH) _{3 - and} (ch _2- o) _z / ^CH 2 ° H> 4 x where z = 1, 2, 3, or CH ₂ -O) _x resins containing 50 mole% of functional groups in their molecule 80 to 20% by weight of polyester resins CO © - .. coo - or CH = C - C00 - CH, - CH - CH, - O ^{2 2} OH ² 0.05 to 10% by weight of rotoiniclator, 5 to 30% by weight of pigment, 0.1 to 5% by weight of dye, 0.05 to 4% by weight of thixotropic agent, 0.05 to 4% by weight of flow agent, 0.01 to 0%. % by weight of a thermal polymerization stabilizer, 0 to 5% by weight of a plasticizer ε 0 to 10% by weight of an active diluent containing 3 to 8% by weight of a photoinitiator, 40 to 60% by weight of olefinic ester compounds, 10 to 30% by weight of solvent naphtha, 10 to 30% by weight of ether compounds containing functional groups in their molecule R ₄ -O-CH-CH ₂ »O--, where S ₄ * CHY-, CjHj, C- ^ y, legs _θ -, and 0.05 wt% stabilizer, thermal polymerization., 2. A polyaeml mixture according to claim 1, wherein the photoinitiator defines benzyldimethyl ketal or 2 chlorothioxanthone; 3. A photopolymer blend according to claim 1, wherein the photoinitiator comprises a blend of benzyl dimethyl ketal with mercaptobenzothiazole in a weight ratio. 0.1 to 1 2. 4. A photopolymer mixture according to Claims 1 and 3, characterized in that it comprises, as a polyester resin, the reaction product of an epoxy resin with an eethacrylic acid having an acid number of less than 15 mg KOE per g. 5. A photopolymer blend according to claim 1 or 2, characterized in that it comprises, as the polyester resin, the reaction product of phthalic anhydride and 1,2 propylene glycol in a molar ratio i; 1 with an acid number of 80 to 10 mg KOH per g, 6. A photopolymer blend as claimed in claim 1 or claim 4 wherein the olefinic ester compound comprises triaethylolpropentriacrylate. 7. A photopolymer composition according to claim 1 or claim 5, wherein the olefinic ester compound comprises a mixture of 2-hydroxyethyl methecrylate with triaethylol propane triacrylate in a weight ratio of 1: 0.9 to 1: 1. 8. A photopolymer composition according to claim 1, characterized in that it contains pentae rythrit-tetrakis ([beta] -mercaptopropionet) as plasticizer. 9. A photopolymer composition according to claim 1, wherein the photoinitiator comprises a mixture of benzildiaethyl ketal-mercaptobenzthiezol-dimethyleniinoethanol in a weight ratio of 1: OJ: 0.1 to 1: 1.1: 2. 10. The photopolymer mixture of claim 1, wherein the crosslinking agent is iteconic acid.