DE2311896A1 - LIGHT SENSITIVE POLYMER MATERIALS AND THEIR USE FOR THE PRODUCTION OF PRINTING FORMS - Google Patents

Description

PATENT LAWYERS

DR. ING. A. VAN DERWERTH DS. FRANZ LEATHER

21 HAMBURG 9O O MONCHEfI 8O

WILSTORFER STR. 32 ■ TEL. (04 11) 77 OS 61 LUCILE-GRAHN-STR. 22 - TEL. (08 11) 47 29 47

Munich, March 9, 1973 Kutner Case 20

Hercules Incorporated, 910 Market Street, Wilmington, Delaware, USA

Photosensitive polymer compositions and their use for the production of printing forms

The invention "relates to water-soluble, light or photosensitive Polymer compositions which are suitable for the production of printing forms.

Light or photosensitive polymer compositions, which under the Influence of actinic light can be converted into structures which are suitable as printing forms or letterpress forms are generally described in U.S. Patent 2,760,863. The described in this US patent, polymerizable layers are made from polymeric components that are soluble in organic solvents. The use of such volatile solvents is dangerous; in U.S. Patent 2,927,023 is an improvement on the Compositions described in US Pat. No. 2,760,863, namely photosensitive compositions which are exposed and, by means of an aqueous processing solution, for the production of polymeric printing forms or letterpress forms can be developed. However, the materials own

309840/1083

DEUTSCHE BANK AC. HAR (URC 93 / SO8I3 POSTSCHECK., HAMtURG 11733 (1 TtLECRAMME: L E D E R E R P A T E N T MÖNCHEN

A- -

einneonnnen m ..A ± pl ^. ' 2311896

US Pat. No. 2,927,023 has the disadvantage that it does not are thermoplastic. This means that they are not made with the most readily available and appropriate facilities which are usually used for the mixing and molding of thermoplastic polymers "are used as Banbury mixers, two-roller mills, and with equipment for compression deformation and extrusion.

The object of the invention is to eliminate the disadvantages of these known, photosensitive polymer compositions.

According to the invention this becomes photopolymerizable by a Mass enables which is a water-soluble. Cellulose derivative

, an addition of poly-

merizable, ethylenically unsaturated monomer and one Includes photoinitiator, this composition being characterized in that the cellulose derivative is a thermoplastic hydroxypropyl cellulose with an MS value of at least 2 is that the

Monomers its unsaturation in the form of at least 2 CH »C - C ·

Has radicals, where H is hydrogen or a C ^ - C ^ -alkyl radical and that the photoinitiator is ^{thermally stable up to 180 0} C, the mass of 0.5 to 25 wt. ~% Of the monomer and 0.5 " up to 10% by weight of the photoinitiator, based in each case on the weight of the cellulose derivative.

The invention also relates to a method of production a letterpress form, wherein a film made of a photopolymerizable Mass is produced, the film is coated on a carrier, selected areas of the film are exposed to actinic light and the unexposed areas are washed away or washed out, the The process is characterized in that the mass described above is used as the mass and the film was thermoformed.

09840/108

2311836

The invention "also relates to the material obtained, which a photopolymerizable layer consisting of that previously described Mass insists on one. Includes carrier.

The thickness of the photopolymerizable layer can be from 0.076 mm to 6.35 ram and it can be an intermediate layer a resin or polymer may be present, which adheres to the support and the photopolymerizable layer. Advantageously this intermediate layer absorbs actinic light. As such, the absorbent layer preferably contains one Pigment like carbon black that light over a broad spectral range absorbed, whereby the light energy absorbed therein is converted into heat energy, thereby increasing the effective Photosensitivity results. Such an absorbent Layer can also advantageously act as an antihalation layer by reducing reflectivity, when the substrate reflects light, e.g. B. in the case of metal plates or foils, which because of their desired physical or mechanical properties are very useful.

The invention is explained in more detail below with the aid of examples; In these examples, all parts are based on weight, unless stated otherwise. The terms "MS value" and "DS- ¥ ert ⁿ used in the description have the following meanings: The MS value denotes the molecular substitution and is the average number of moles of the reactant that is combined with the cellulose per anhydroglucose unit and the DS Value denotes the degree of substitution and is the average number of hydroxyl groups substituted per anhydroglucose unit in the cellulose. Since there are three hydroxyl groups in each anhydroglucose unit in the cellulose molecule, the maximum DS value is 3 »and the DS and MS values are for the alkyl -, carboxyalkyl or acyl derivatives of cellulose. For the hydroxy alky Ideriva te the MS value can be

309840/1083

■ - 4 - ■ ■

must be greater than 3, since every hydroxyalkyl radical in the Cellulose molecule is introduced, provides an additional hydroxyl group, which in turn undergoes a hydroxyalkylation is accessible. As a result, side chains can be sizable Length to be formed on the cellulose molecule.

example 1

A 10% solution of hydroxypropyl cellulose (DP * '*' 24-0, Mol.Gew. * 100,000, HS value - 4) was prepared in methanol, which was 5 phr (parts per 100 parts, based on the hydroxypropyl cellulose) N, N ¹ -methylene bis (acrylamide) and 5 ^T pH benzophenone. With the aid of a doctor blade, a 0.635 mm thick film of this solution was poured onto a sheet of grained aluminum. After allowing the solvent to evaporate for an hour, a negative, which had both a line image and a halftone image, was placed over the film and exposed to a 275 W GE (daylight lamp at a distance of 5.1 cm for a period of 15 minutes) During this period of time, the polymer which was exposed through the transparent surface areas of the negative was made insoluble.

*) DP * degree of polymerization

Example 2 '

A castex ¹ film was produced as described in Example 1, using a hydroxypropyl cellulose with a lower molecular weight and a lower MS value, namely mol "wt. «= ^ 80,000 and MS value« 3.1 _{3 were} used. The film was exposed through a negative with a 275 W GE daylight lamp at a distance of 12.7 cm for a period of 10 minutes. After removing the soluble polymer in

3098-0 / 1083

running tap water, an image of the negative with good resolution was obtained.

Examples 5 to 8

A series of films of hydroxypropyl cellulose on grained aluminum were prepared as described in Example 1. They were passed through a 21-stage photosensitive filter (Stouffer Graphic Arts Equipment Co., South Bend, Ind .), which was produced according to the information in GATE ¹ RESEARCH BULLETIN No. 215 "The Sensitivity Guide", Verlag Graphic Arts Technical Foundation. The soluble polymer was washed away with water using a sponge suitable for such photographic material. A summary of these tests and the highest fixed level achieved are shown in Table I below:

Tabel bis- (acryl I. Sensitivity filter transparency example Benzophenone methylene amide) TpH highest (%) No. TpH 1.0 step 6th 0.5 9 50 3 0.5 1.0 3 3 4- 1.0 5.0 11 2.2 5 1.0 5.0 12 · 0.56 6th 1.0 5.0 " 16 0.40 7th 2.5 17th 8th 5.0 Examples 9 to 14-

A series of 0.127 mm thick films was made from the hydroxypropyl cellulose of Example 1 according to the general in Example 1 specified procedure using the

309840/1083

in the following Table II listed photoinitiators and Monomers produced. The films were passed through the sensitivity filter as used in Examples 3 to 8 while a period of 1 minute with a 275 w * GE daylight lamp exposed at a distance of 8 inches. After washing away the soluble polymer with water, the highest, solid level was determined. It is listed in Table II below.

Table II

At- photoinitiator monomeric sensitivity filter

spiel Typ TpH Typ TpH highest transparency

No level. (%)

Benzophenone 2.5 N, N '- (Oxydi ~ 5

methylene; bisacrylamide

Benzophenone 2.5 "10

Benzoin 2.5 "" 5 methyl ether

Benzoin 2.5 "10 methyl ether

Benzophenone 2.5 K ", N'-trimethyl-5

lenbisacrylamide

Benzophenone 2.5 "10

12th

2.2

15th 0.8 14th 1.1 16 0.56 9 6.0

1.1

Example 15

A warm solution of 1.0 g of benzophenone and 1.0 g of N, N'-methylenebis (acrylamide) in 30.8 g of benzene and 11.9 g of methanol was mixed with 40 g of the hydroxypropyl cellulose from Example 1. The polymer obtained, highly swollen was left under a hood and finally dried in a vacuum oven at 40 ⁰ C to dry. The mixture was then verforjnt under pressure while it was held in einem.0,635 now thick frame on a grained aluminum sheet in a press at 110 ⁰ C for a period of 5 minutes. The plate with the photosensitive

309 8 4 0/1083

Polymer was irradiated through a negative with a 275 W GE daylight lamp at a distance of 10.2 cm for a period of 3 minutes. The image was developed by washing with water for 20 minutes with the aid of a sponge, and the insoluble polymer was dried in a stream of air. An image was obtained with a relief height of 0.635 mm with good resolution, which was suitable for use as a printing plate for letterpress or letterpress printing.

Example 16

Example 15 was repeated except that 0.04 g 2,6-di-tert-butyl-p-cresol and 0.1 g dilauryl thiodipropionate entered in the approach. Substantially the same result as in Example 15 after the irradiation and the Wash out or "etch" with water obtained.

Example 17

Example 16 was repeated except that the dried Mix on a grained aluminum foil at 175 ° C for a Was deformed under pressure for a period of 3 minutes. Substantially the same result as in Example 15 according to FIG Obtained irradiation and washing out with water.

Example 18

Example 16 was made with a hydroxypropyl cellulose with a molecular weight of ~ 150,000 and a. Repeated MS value of 4.8. After irradiation and washing with water, substantially the same result as in Example 15 was obtained.

Example 19

Example 15 was made using a lower molecular weight, lower MS, hydroxypropyl cellulose, viz DP "60, Mol.Gew." 25,000, MS value ■ 3.4, repeated. The The polymer was irradiated through a negative as in FIG

309840/1083

Example 15 for a period of 10 minutes, then washing was carried out with water. A result similar to that in Example "15 was obtained. ■,

Example 20

100 parts of the hydroxypropyl cellulose from Example 1, 2.5 parts of benzophenone, 2.5 parts of N, K'-methylenebis (acrylamide), 0.1 part 2,6-di-tert-butyl-p-cresol and 0.25 part of dilauryl thiodipropionate were intimately mixed together dry. This mixture was then placed on a two roll mill for 5 minutes at a temperature of 120 C and rolled at 135 C for a period of 3 minutes under compression molding on a grained aluminum foil Formation of a 0.635 mm film of photosensitive polymer, that adhered to the substrate. After irradiation and washing out, this mass was used as a printing plate for, as in Example 15 Letterpress.

Examples 21 to 25

The following compositions were prepared as described in Example 20. Irradiation through a transparent original, which consisted of a line copy and halftone images, using a GE 275 W daylight lamp at a distance of 20.3 cm for a period of 10 minutes, followed by washing out with water yielded solid letterpress forms Ink provided and used to print on a Vandercook No. M clearing press manufactured by Vandercook & Sons, Inc., Chicago, 111., USA. Ink transfer was excellent and the copy had good resolution in both the bar areas and the halftone areas. The masses are listed in Table III below.

309840/1083

Table III N, N ¹ -methylene brass (acryl
amide) TpH Di-t-butyl
p-cresol
TpH at
game
No. Benzophenone Monomer
TpH type N, H'-ethylidene-bis
(acrylamide) 7.5 0.1 21 1.0 N, N'-propylidene-bis
(acrylamide) 10.0 0.1 22nd 2.5 N, N ¹ -benzylidene-bis
(acrylamide) 10.0 0.1 23 2.5 1,3,5-triacryloylhexa- 10.0 0.1 24 2.5 10.0 0.1 25th 2.5

hydro-1,3,5-triazine
(Primafix p-100, commercially available product
of BASF)

Example 26

A photosensitive hydroxypropyl cellulose photopolymer composition which had been prepared according to the procedure given in Example 20 and which was composed of 100.0 parts of hydroxypropyl cellulose (DP ~ 120, Mol.Gew. «50,000, MS value 3.6), 1.0 Parts of benzophenone, 10.0 parts of N, N ¹ -methylene-bis (acrylamide), 0.1 part of 2,6-di-tert.-butyl-p-cresol and 0.25 part of dilauryl thiodipropionate resulted in a 0.635 mm film compression molded adhered to a sheet of grained aluminum. Two rectangles of this laminate, approximately 2.5 x 5.1 cm, were weighed out and exposed for 5 minutes under a 275 W GE daylight lamp, one sample at room temperature and the other while on its Surface was heated ^{to 90 0 C.} The samples were then immersed in water for 10 minutes, pounded dry from surface water, and reweighed. The polymer irradiated at room temperature had a weight increase of 35%, while the polymer irradiated at elevated temperature had gained 15% in weight. This shows that the latter had achieved a higher crosslink density.

309840/1083

Example 27

Solutions of the hydroxypropyl cellulose from Example 1, (10%), were made in methanol containing 5 phr Njlf'-methylene-bis- (acrylamide) and $ TpH of the following photo initiators contained in the respective solutions: Benzoin, Benz ο inme thy läther, Benzoin ethyl ether, benzoin isopropyl ether, 9 »10-phenanthrenequinone, Benzil and 1,4-naphthoquinone. Films of this polymer solution were made as in Example 1 and under a 275 W GE daylight lamp at a distance of 8 inches for 10 minutes exposed. Attempts to dissolve these films in water indicated that they had become insoluble. A similar one Film made in exactly the same way but without a photoinitiator was as before after exposure indicated, completely soluble in water.

Example 28

Solutions of the hydroxypropyl cellulose from Example 1 (10%), were prepared in methanol containing 2.5 phr of benzophenone and 5 phr of the following monomers in the respective solutions Contains: tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, Pentaerythritol trimethacrylate, trimethylolpropane triacrylate, Pentaerythritol triacrylate and pentaerythritol tetraacrylate. Films prepared and exposed as in Example 27 were placed in water insoluble. One in exactly the same way, but without anything Similar film produced by monomers was completely soluble in water after the irradiation carried out as before.

Example 29

The following ingredients were ground together in a mortar: 1.5 g benzophenone, 6.0 g N, N ¹ -methylene bis (acrylamide), 0.15 6 dilauryl thiodipropionate and 0.06 g 2,6-di-tert, .-butylp-cresol. This mixture was with 60.0 g of the hydroxypropyl cellulose from Example 1 and 3.6 g of a water-soluble polyethylene oxide with an average molecular weight of 400

309840/1083

(Trade name Carbowax 400 from Union Carbide) and mixed briefly in a Waring mixer. 107ϊ7 S Ludox AS (trade name of DuPont for 30% solids colloidal silica gel having a particle size of 13-14 millimicrons) was then added and the pasty mixture was hand stirred, spread into a thin sheet and air dried at room temperature . The resulting film was placed on a two roll mill and rolled for 5 minutes at 121 ⁰ C.

A plate of 101.6 mm × 101.6 mm × 0.635 mm on a 0.152 mm base made of grained aluminum was formed under pressure from 9 S of the rolled mass. A photographic negative was then placed over the plate, which was then placed under a 275 W GE daylight lamp at a distance of 22.9 cm for 10 minutes. The exposed plate was then exposed to a jet of water from a nozzle for 5 minutes. The surface areas not exposed to light were completely removed, the exposed surface areas remaining in relief. The plate was dried in a stream of air at 50 ^° C. for 1 minute.

Example 50

A photosensitive polymer plate was made as in Example with the exceptions that the Ludox AS through 120.0 g Ludox TM (trade name DuPont, colloidal silica gel with 4-9% solids) and the content of water-soluble Poly (ethylene oxide) with an average molecular weight of 400 (trade name Carbowax 400) was increased to 7 * 2 g. A photographic negative was placed over the plate with a 275 W GE daylight lamp at a distance of 8 inches irradiated for 5 minutes. It became a printing plate for letterpress printing after washing out with water, as described in Example 29, obtain.

309840/1083

Example 51

A composition was prepared as described in Example 29, with the exception that half of the N, N'-methylenebis (acrylamide) by 1,3,5-triacryloylhexahydro-i, 3,5-triazine was replaced. The rolled mass was compression molded to a thickness of 0.635 nm on a steel plate, the surface of which was roughened by sanding. A high pressure image was obtained by irradiating with a 275 W GE daylight lamp through a Negative followed by water spray etching. Images produced in this way were successful in Printing on a Hoe rotary press operating at a speed of 25,000 prints per hour.

Example 52

A composition as described in Example 29 was prepared with the exception that a quarter of the Ν, Ν'-methylenebis (acrylamide) replaced by N, N'-ethylidene-bis-acrylamide) became. Printing plates were made and successfully used as described in Example 31.

Example 35

A composition as described in Example 29 was prepared using three times the amount of the reagents given herein. The mixture was spread on a sheet of polytetrafluoroethylene (trade name Teflon) and allowed to dry to a moisture content- "of about 10%. The partially dried sheet was cut, then chopped in a Waring mixer and passed to a Brabender extruder at 100 ^° C supplied which had an injection molding tool having a hole. the pellet-shaped rod was then mm again at 120 ⁰ C by a slot die of 0.51 extruded. the film obtained was coated on an aluminum substrate by passing the film was placed on a grained aluminum sheet ,

309840/1083

which had been "moistened" with a thin film of water and then the composite body is placed in a press at room temperature and a pressure of 4-2.2 kg / cm is applied. A satisfactory lamination was also obtained by wetting the aluminum sheet with methanol instead of water became. Alternatively, the lamination was carried out by spraying the aluminum sheet with a pressure-sensitive resin-rubber adhesive in a hydrocarbon solvent, laying down the extruded film of photosensitive polymer composition the adhesive-coated surface of the aluminum and applying pressure to the composite. In all cases High-performance relief printing plates were made following the procedure of Example 29.

Example 34-

A composition comparable to that of Example 29 except that the poly (ethylene oxide) had an average The molecular weight of 400 (trade name Carbowax 400) was omitted using three times the amounts of the remaining components. This mass was then further treated according to the procedure of Example 33, wherein a satisfactory letterpress plate was obtained.

Example 35

A plate made of photosensitive polymer as described in Example 29 described was prepared. The plate was in a vacuum frame through a negative with a medium pressure mercury arc lamp (Ascor Addalux 1406-02) at a nominal distance of 50.8 cm from the lamp (real distance about 101.6 cm) irradiated for a period of 10 minutes. When etched with water, a letterpress shape was obtained.

309840/1083

Example -36

A vacuum frame was preheated to about 70 ⁰ C by being exposed to the lamp described in Example 35 for about 10 minutes. A plate as described in Example 29 was exposed through a negative with this lamp at a nominal distance of 7/62 cm (actual distance about 58.4 cm) for a period of 30 seconds. When washed with water, a letterpress form was obtained.

Examples 37 to 41

The compositions of these examples were each made from 60.0 g of the hydroxypropyl cellulose from Example 1, 1.5 g of benzophenone, 6.0 g of N ^ N'-methylenebisiacrylamide, 0.15% of mlauryl thiodipropionate, 0.06 g of 2 , 6 M-terte-butyl-p-cresol, 3 * 6 g of poly (ethylene oxide) with an average molecular weight of (trade name Carbowax 400) and the amount of filler indicated in Table IV below. In each case the ingredients were mixed briefly in a Waring blender and · the resulting compositions processed 15 minutes for a two roll mill at 110 ⁰ C, then compression molded to a 0.635 mm film that was adhered to a sheet of grained aluminum. As described in Example 29, relief molds were made.

Table IV

example
No.

filler

Supplier and quantity particle size

37 -silica gel (Hi-SiI 233)

38 calcium carbonate (Purecal SC)

39 talc

(Mistron Superfrost)

32.0 grams of Columbia-Southern Chemical Corp. j 22 millimicrons

Wyandotte Chemical Corp., 32.0 grams, 50-60 millimicrons

32.0 g United Sierra, 97% less than 5 microns, 58 % less than 1 micron

3 0 9 8 4 0/1083

Table IY (port setting)

By-supplier and

match filler amount (particle size

talc

(Mistron Superfrost) 90.0 g

Clay (UC540), chemically 52.0 g United Sierra, 97% less modified kaolin than 10 microns, 55% less

than 1 micron

Example 42

40 g of N, N'-methylenebis (acrylamide), 10 g of benzophenone, 0.4 g of 2,6-di-tert-butyl-p-cresol and 1.0 g of dilauryl thiodipropionate were ground together in a mortar, then briefly mixed with 400 g of hydroxypropyl cellulose (Mol.Gew. = 100,000, MS value «5.6) in a Waring mixer. The combined solids were then added to 540 grams of Ludox AS (50% solids, colloidal silica gel having a particle size of 15-14 millimicrons) and 18.0 grams of poly (ethylene oxide) having an average molecular weight of 400 (trade name Carbowax 400) in a Hobart Mixer (made by The Hobart Manufacturing Co., Troy, Ohio, USA) and mixed together until a uniform paste is formed. The paste was spread out on a sheet of polytetrafluoroethylene (trade name Teflon) and air-dried to a moisture content of about 10%. This material was then processed on a two roll mill at 121,1 ⁰ C for a period of 5 minutes. The rolled material was at 121.1 ⁰ C compression molded 4 minutes a 0.655 inm film which was adhered to a 0.152 min foil of granulated aluminum which had been previously primed with a solution consisting of 25 »g of hydroxypropylcellulose O, 1.25 g of dimethylolurea, 125.0 g of water and 0.5 g of buss had been prepared. Before the addition

309840/1083

The pH of the carbon black was adjusted to 2 using p-toluenesulfonic acid set.

The plate was passed through a photographic negative while held in a vacuum frame using a ' 275 W GE daylight lamp at a distance of 22.9 cm for 9 minutes exposed. The exposed film was sprayed with water below 4.2 kg / cm from nozzles which were about 6.35 cm removed from the plate, developed over a period of 5 minutes. The pressure plate was on the bearings attached to a Hoe-Eotationspress, which with Iformwalzen a durometer hardness of 4-5 (Shore A) and pressure felt rollers one Hardness of 85 - 90. Adjusting the strip at 9 »5 mm to the cylinder and 7.94 mm to the plate became the indentation set to 0.18 mm. Printing tests were carried out with the press at a speed of 40,000 prints performed per hour. Both the bar and halftone areas had good resolution. After more than 28,000 Once prints had been made, there was no noticeable change in print quality, nor any sign of wear and tear of the image on the potopolymer plate.

Example 45

A mass was produced which contained 200.0 g of hydroxypropyl cellulose (mol. Weight - 100,000, MS value = 3.9), 5.0 g of benzophenone, 20.0 g of N, F-methylenebis (acrylamide ), 0.5 g of dilauryl thiodipropionate, 0.2 g of 2,6-di-tert-butyl-p-cresol and 270 g of a 40% dispersion of colloidal silica gel in water. This mass was spread in a thin layer and allowed to dry. The dried mass was processed on a Zweiwalζenstuhl 5 minutes at 121 ⁰ C and then molded than 0.635 mm layers on 15 x 17 "8 cm aluminum materials with a thickness of 0.15 mm. The resulting plates were passed through a negative for various times ranging from 1 minute to 20 minutes using a 250 W GE daylight lamp at a distance

309840/1083

exposed from 22.9 cm. The plates were then treated with water "

about 4.6 kg / cm "sprayed, the non-exposed areas the plates have been removed. The panels were then allowed to dry. Using a commercially available In a mat press, a Burgess Color Tex mat was pressed with heating against the surface of an array of these panels. The mat was dried in a curved configuration using a commercially available mat dryer. Molten lead was poured against the mat surface, forming a conventional stereographic lead printing form became. This plate performed well on a Goss rotary press in terms of print quality comparable to the original plates when mounted and used for direct printing on the same press.

Example 44

It became a solution of 10.0 parts of hydroxypropyl cellulose (DP - 300, mole weight - 120,000, MS value - 3.8), 0.50 parts N, N * -methylene bis (acrylamide) and 0.25 part of benzophenone in 79> 2 parts of methanol produced. This solution was poured onto a sandblasted copper plate with a 0.254 mm blade and air-dried to obtain a smooth picture became. This PiIm was covered by a negative for 5 minutes Placed in a vacuum frame and using a 2000 W mercury lamp (Berkey) at a nominal distance of 5.1 cm exposed. The exposed film was developed by washing under running water, giving a good image revealed. The film was dried in an oven and the plate was then coated with a red lithographic ink emulsion coated. The copper turned red from the color, while the image area did not take on the color.

309840/1083

Example 45

A mass was produced which contained 585 »O g of hydroxypropyl cellulose (Mol.Gew.» 100,000, MS value = 3.8), 58.5 g of Ν, Ν'-methylenebis (acrylamide), 14.6 g Benzophenone, 1.5 g of dilauryl thiodipropionate, 0.59% of 2,6-di-tert-butyl-p-cresol and 990.0 g of a 40% dispersion of colloidal silica gel in water. A portion of this mass was diluted to about 10% solids with water. The diluted mass was coated on a silk screen with the aid of a color brush and allowed to dry. The dried screen was exposed for 10 minutes through a transparent positive using a 250 W GE daylight lamp at a distance of 22.9 cm. After exposure, the screen was washed with a weak stream of cold water. The areas of the coating which had been protected from the action of light by the dark sections of the transparent original had remained soluble and were removed in the washing step, while the exposed areas of the coating had been made insoluble and were not removed during the washing step. After drying, the resulting stencil, supported by the silk screen, was used to print reproductions of the original artwork by printing a commercially available screen printing ink through the surface onto paper *

Example 46

Solutions of the hydroxypropyl cellulose from Example 1, methyl cellulose (DS value "■ 1.8, methoxyl content» 29.8%), hydroxyethyl cellulose with an MS value of 1.5 and hydroxyethyl cellulose with an MS value of 2.5 in Concentrations of 2% prepared in water, which, based on the respective polymers, contained 2 parts of N ₁ N ¹ -methylene bis (acrylamide) and 2 parts of benzophenone, the latter being added in the form of an alcoholic solution about 0.635 buh thick films cast on panels of grained aluminum

309840/1083

These polymer films of a 275 W GE daylight lamp became solvent exposed through a sensitivity filter at a distance of 22.9 cm for a period of 10 minutes. After briefly washing out with water, the following results were obtained:

1) The hydroxypropyl cellulose mass yielded a solid polymer through step no. 5;

2) the methyl cellulose mass was completely washed away;

3) the hydroxyethyl cellulose mass with MS value = 1.5 provided a slight shadow of the negative, but the mass was completely washed away and

4 ·) delivered the hydroxyethyl cellulose mass with an MS value = 2.5 a slight hint of an insoluble film, but nothing was retained during washing, even in the lowest, most permeable level.

The iOtopolymer masses according to the invention can be based on solutions a suitable support such as granulated aluminum or steel plates or cast on polyester film. Alternatively, they can preferably be equipped with equipment for the production of plastics on such substrates made of metal or plastic resins be deformed by heat. When working via the solution, a methanolic or aqueous solution of the Hydroxypropyl cellulose in concentrations of 5 to 20% by weight produced and the ethylene-like unsaturated monomer and the photoinitiator are added. The solution is then on the carrier is poured onto its surface with the help of a Spread the squeegee and let the solvent evaporate. Films with a thickness of 0.076 mm or more are on this Way conveniently made. In the preferred mode of operation of the heat deformation, the constituents of the mass can first dry on a Henschel mill, in a Waring mixer or a tumbling device to be mixed intimately with each other mixed, dry mass. The ingredients are then further melted on a two-roll mill

309840/1083

or mixed by extrusion at temperatures between approximately 90 ^° C. and 180 ^{° C.} This mixture is then processed by molding or extrusion on a support made of metal or a plastic resin at temperatures between about 90 ⁰ C and about 180 ⁰ C to the Rohdruckformen. During the melt mixing and preparation steps, the presence of small amounts of water, e.g. B. about 5 to · about 10 wt .-%, based on the total mass, facilitate the processing of the mass and ^{enable the use of lower temperatures in the range of 90 to 180 0} C, z. B. Temperatures from about 90 to about 120 ⁰ C and preferably from about 100 to about 120 ⁰ C. Films with a thickness of z. B. 0.635 minutes or more are easily made by the heat deformation technique.

The hydroxypropyl cellulose which is the major organic component of the photopolymer composition of the invention possesses at least two bound propylene oxide molecules (MS value = 2) per anhydroglucose unit and preferably 3 "to 5 and more, particularly preferably 3j2 to 4-, O-bonded propylene oxide molecules. When the masses are made using the preferred heat deformation technique, especially when they are by extrusion are formed, the hydroxypropyl cellulose should have an MS value of at least 3 * 4 and preferably an MS value from about 3 »8 to about 5> 0. The molecular weight of the Hydroxypropyl cellulose can vary from about 20,000 to 1,200,000. However, preferred materials for making letterpress plates or forms are those having a molecular weight in the range from about 25,000 to about 200,000 because of the easier etching off or washing away of the unexposed areas with water. The hydroxypropyl cellulose can be prepared by the methods described in U.S. Patents 3,278,520 and 3,278,521 will. This hydroxypropyl cellulose can be modified to some extent by other substituents. So can

30 9 8 40 /. 108 3

a low degree of substitution by benzyl residues (DS value = 0.2 to 0.8) to improve an even more satisfactory resistance of the crosslinked surface areas to water contribute during the development stage. A modification by allyl residues (DS »0.1 to 0.5) can also lead to the formation of a somewhat more densely networked system can be used.

The components of the ethylene-type unsaturated monomers of the compositions according to the invention have their unsaturation in J? Orm

of at least two η

CHp "C - C - radicals, in which R is hydrogen

or a C. to C.sub.1 alkyl radical. One of the preferred monomers is 1,3,5- ^ iacryloylhexahydro-1,5 »5-triazine. This connection and related compounds such as the corresponding methacrylol derivatives have the structural formula:

C - C »CH ₀ R

₀ N NO

CH _p . C - fi / ™ { ^X C - C = CH ₂ (I)

R R

wherein R is hydrogen or a C 1 -C 4 alkyl radical.

Other suitable monomers can have the following structural formula: _QQ

CH ₀ »C - C ■ - X - A - X - C - C = CH ₀ '(II)

R R

0 9 8 4 0/1083

in which R is in turn hydrogen or a C.sub.1 -C.sub .-- alkyl radical and X is each either -NH- or -0- and A is alkylene, substituted alkylene, or alkyleneoxyalkylene. Examples of the latter compounds are those having the following formula:

0 0

CH ₀ - -C - C - HH - CH ₀ OCH ₀ - MHC -C = CH ₀ (III) c. ι cd ι cL

B ■ - R

A preferred monomer with this formula is N, N'-oxydimethylene-bis (acrylamide).

If X in the formula (II) given above is -HH-, however, A ■ is an alkylene or substituted alkylene radical, it is a further preferred monomer, namely Ν, Ν'-methylenebis (acrylamide). This compound is one of the valuable group of monomers identified by compounds of the following Formula is reproduced:

0. 0

CH ₀ »C - C - NH - (CHR ') -.HH-CO-OH ₀ (IV) RR

wherein R is hydrogen or a C.sub.1 -C.sub.1 -alkyl radical, R ^{1 is} hydrogen, one C.sub.1. - is 0, -alkyl or phenyl, η is 1 to 6 and the total number of carbon atoms in - (CHR ¹ ) - is not higher than 10.

Typical and advantageous compounds of the formula IV given above are N, N'-methylene-bis (acrylamide), Ν, Ν'-methylene-bis (methacrylamide), N, N'-methylene-bisialpha-ethyl acrylamide), N ₅ N ¹ -Methylene-bis (alphapropylacrylamide), N, N'-ethylene-bis (acrylamide) N, N'-ethylene-bis (methacrylamide), N, N ^l - (i, 6-hexamethylßn) -bis (acrylamide), N , N '- (1,6-hexamethylene) -bis (methacrylamide), Ν, Ν ¹ -Ä'thylidene-bis (acrylamide), NjN'-ethylidene-bisCmethacrylamide),

309840/1083

N ₁ N ¹ -benzylidene-bis-acrylamide), H ₅ Ii ¹ -butylidene-bis-methacrylamide) and N 1, N'-propylidene-bis-acrylamide). These compounds can be prepared by means of conventional reactions known per se, e.g. As described in U.S. Patent 2,475,846.

Further useful monomers are those in which X in formula II given above is -0-. When A is an alkylene or substituted alkylene, the compounds are di-, tri- and tetraacrylates of certain polyhydric alcohols. These Acrylates can be represented by the following general formula:

O -O- (CE ¹ E ¹ O - 0 0 - C η n η ι C. - C - G E. I. E.

CH ₀ = C - C - 0 - (CE ¹ E ") - 0 - G - C - CH ₀ (V)

C. τη j

where E is hydrogen or a C ^ - C, -alkyl radical, R ¹ is hydrogen, a C ^ - C, -alkyl radical,

-OH, -CH ₂ OH or -CH ₂ OC-C = CH ₂ ,

R "hydrogen, a C ^ - C ^ -alkyl radical,

- CH ₀ OH or -CH ₀ OC-C = CH ₀

η 1 to 6 and the total number of carbon atoms "in - _{n are} not more than 11. Typical and advantageous compounds hereof are: ethylene glycol diacrylate, ethylene glycol dimethacrylate, ethylene glycol di (alpha-ethyl acrylate), ethylene glycol di (alpha-propyl acrylate), 1, 3-propylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,5-pentanediol dimethacrylate, glycerol diacrylate, glycerol triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, eentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol ethyl acetate and pentaerythritol triacrylate, pentaerythritol ethacrylate acrylate, pentaerythritol ethylacrylate

309840/1083

Closely related to the aforementioned acrylates are those compounds derived from di-, tri- and tetraethylene glycol and di- and tripropylene glycol. These connections correspond of formula II, wherein X is -0- and A is an alkylene oxyalkylene group is. More specifically, they can be represented by the following formula:

0 0

CH ₀ «= C - C - 0 - (CHR ¹¹¹ CH ₀ O) - C - C = CH ₀ (VI)

C. I CU \ C.

R. R.

wherein R is hydrogen or a C.sub.1 -C.sub.1 -alkyl radical, R ¹ "is hydrogen or the methyl radical, η 2 to 4 if R" is hydrogen, and 2 to 3 if R ' ^{M is} the methyl radical. Typical and advantageous of these compounds are diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, dipropylene glycol diacrylate, dipropylene. glycol dimethacrylate, tripropylene glycol diacrylate and tripropylene glycol dimethacrylate.

The amount of monomer used to cause crosslinking the hydroxypropyl cellulose component in the compositions according to the invention can be from about 0.5 to about 25% by weight, based on the Hydroxypropyl cellulose. However, that is required to achieve effective crosslinking of the hydroxypropyl cellulose Amount of monomers! usually no more than about 10%. A preferred range is from about 2 to about 10 weight percent based on on the hydroxypropyl cellulose. The efficiency of such comparatively low concentrations (0.5 "to 10%) Monomers! on the hydroxypropyl cellulose is unique and surprising and it is believed that this is the fact It is attributable that this cellulose derivative has a high value

on oxypropyl substituents,

CJH ₃

-0-CH ₂ CH-

309840/1083

possesses, each of which has a tertiary hydrogen atom, which can enter into chain transfer with the monomer during the polymerization of the latter. More accurate said it is believed that irradiation of the photoinitiator raises it to an excited state in which it causes a scavenges tertiary hydrogen from the hydroxypropyl cellulose, forming a hydroxypropyl cellulose free radical which forms attaches to the monomer and the polymerization thereof starts. Then the growing polymer chain draws a tertiary hydrogen from another hydroxypropyl cellulose molecule and the resulting hydroxypropyl cellulose free radical reacts with the other end of the growing polymer chain, so that a Crosslinking occurs between hydroxypropyl cellulose molecules and a free radical remains on the growing polymer chain. The repetition of these hydrogen splitting and crosslinking steps results in a conversion of the hydroxypropyl cellulose into an insoluble form.

The photoinitiators of the compositions of the invention are generally known per se and they are considered photo-reducible in the art designated. They represent compounds which absorb actinic light very strongly and thereby up to activated at a point where they withdraw hydrogen atoms from compounds that are hydrogen donors. This reduces the photo initiator itself and the

Hydrogen donor converted to a free radical, typical compounds are benzophenone, 2-chlorobenzophenone, 4-methoxybenzophenone, 4-methylbenzophenone, 4,4'-dimethylbenzophenone, 4-bromobenzophenone, 2,2 ', 4,4'-tetrachlorobenzophenone, 2-chloro -V-methylbenzophenone, 4-chloro-4 ^l -methyrbenzophenone, 3-methylbenzophenone, 4-tert.-butylbenzophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzhroin acetate, benzil, benzilic acid, methylene blue, acetophenone, 9,10-phenantone and 1,4-naphthoquinone. Benzophenones are particularly suitable

309840/1083

and the substituted benzophenones, in which the substituting radical halogen, hydroxyl, carboxyl ^ carboalkoxy, alkyl, alkoxy-amino or are mono- or di-alkyl substituted amino groups.

The alkyl group in any of these substituents can have 1 to 5 carbon atoms. In general, the photoinitiator should be thermally stable at temperatures up to about 180 ⁰ C. The stability at such temperatures prevents premature crosslinking when the compositions of the invention are prepared by heat deformation procedures. Such stability also minimizes any crosslinking in the unexposed areas during exposure caused by the heat generated in the crosslinking reaction and by the heat transmitted through the opaque portions of the transparency. The amount of photo-irritant can be from about 0.5 to about 10% by weight based on the hydroxypropyl cellulose in the photopolymer composition.

In order to prevent premature crosslinking during the heat processing of the photosensitive polymer compositions according to the invention, the incorporation of a phenolic stabilizer is advantageous. Such stabilizers are also known per se, examples these are di-tert-butyl-p-cresol, hydroquinone monomethyl ether, Pyrogallol, quinone, hydroquinone, methylene blue, tert-butyl catechol, Hydroquinone monobenzyl ether, methyl hydroquinone, amylquinone, Amyloxyhydroquinone, n-butylphenol, phenol and hydroquinone monopropyl ether. When used in an amount within the range of about 0.001 to about 1 percent by weight of the hydroxypropyl cellulose are, these stabilizers are to prevent the crosslinking of the photosensitive polymer composition during the thermal Processing completely effective. In this way, such amounts of stabilizer delay and prevent the exposure during exposure Crosslinking as a result of scattered light in the unexposed surface areas of the mass, but they disrupt the crosslinking of the

309840/1083

Mass in strongly exposed areas not strong or delay this, which supports the production of a printing form with an optimal depth and surface configuration will.

The photosensitive polymer compositions can also be up to Contain 55% by weight of an inert, particulate filler, which is practically transparent to actinic light. Typical and advantageous examples of such fillers are the organophilic silica gels, the bentonites, silica gel and powdered glass, all of which have a particle size of less than 10 yum for the maximum dimension. Particle with 0.1 micron or less in size are preferred. Such fillers can be added to the masses and reliefs or letterpress forms give advantageous properties according to the invention. For example, the use of silica gel in the Submicron area a printing form with a harder and more durable one Image, with the photopolymer mass etched away in the unexposed areas in a shorter period of time or can be washed away as if this mass did not contain any filler. In addition, the widened by The particulate fillers caused light scattering the image towards the lower part or base of the plate or mold so that the halftone dots take on the appearance of truncated cones in cross section. Such Points are stronger and have less tendency to break off than points that are more cylindrical in cross-section.

When the photopolymer elements of the invention are actinic light exposed by a photomechanical negative or positive, the hydroxypropyl cellulose polymer will be below the exposed Areas made insoluble, while the polymer underneath the unexposed areas is water-soluble remain. The following washing of the plate removes the soluble polymer, leaving a duplicate of the negative or positive in the Keli'ef

309840/1083

remains behind. The washing is normally carried out only with water, generally at temperatures from 25 to 30 ^° C. The development can often be accelerated by brushing or rubbing. When working on a large scale, the treatment with the water solvent is advantageously carried out by means of blasting or spraying. In some cases it may be advantageous to use smaller amounts of organic solvents such as the short-chain aliphatic alcohols and ketones Suitable solvents of this type include methanol, ethanol and acetone and they are generally used in amounts of no more than 25 to 35 %, and preferably less than about 1 to 5% of the water developer The plate or mold can remove the remaining surface water and any organic solvent that may be present by passing a stream of hot air over the relief or the high pressure mold.

The letterpress forms which were produced according to the invention can be used for all types of printing, but are they are best applicable to those species in which a definite one Difference in height between the printing and non-printing areas is required. to these types include processes in which the ink is carried through the raised portions of the relief, e.g. B. in dry offset printing and in ordinary letterpress printing. The letterpress forms are also used as sample plates in the production of conventional stereographic lead printing plates or forms applicable. In addition to their application in the The photopolymer compositions according to the invention can also be used as light-sensitive cover material to produce letterpress forms (photoresists) can be used over an etchable metal. In this case a thin layer of the mass is exposed in the " Surface areas made insoluble and protects the underneath

309840/1083

lying metal before etching or in procedures for "Photo Etching". Likewise, these masses can be used for production used by lithographic plates. They can also be used in the production of screen printing stencils.

309840/1083

Claims (22)

Pat e η t a n sp r ü c h e \ Photosensitive polymer mass, thereby geke η η - ζ eich η et that it is a thermoplastic hydroxypropyl cellulose which is soluble in cold water and has an MS value of at least 2, from 0.5 to 25% by weight, based on the hydroxypropyl cellulose Ethylene-like unsaturated monomers, the unsaturation of which in the form of at least 2 CH ₂ = O - CO - radicals, R where R is hydrogen or a C -C -alkyl radical, is given and from 0.5 to 10% by weight, based on the hydroxypropyl cellulose, a thermally stable photoinitiator at temperatures up to 180 C. 2. Composition according to claim 1, characterized in that that the hydroxypropyl cellulose has an MS value of 3 to 5. 3. Mass according to claim 2, characterized in that that the hydroxypropyl cellulose has an MS value of about 4 owns. 4. Composition according to claim 1, characterized marked, that the ethylene-like unsaturated monomer is a compound of the following formula: CC = CH ₀
ι ι 2 Γ E. CHX """" CH ₀ . , 2, 2 CH ₀ = C - C ^ - ^ CH ₀ - ^ ^ C - C ■ - CH E E 3098 L Π / 1083 c. wherein R is hydrogen or a C ^. - is C 1-4 alkyl radical. 5. Composition according to claim 4-, characterized in that the ethylene-like unsaturated monomer 1,3> 5-triacryloylhexahydro-i ^^ - triazine is. 6. Composition according to claim 1, characterized in that the ethylene-like unsaturated monomer is a compound of the following formula is: 0 .0 CH ₀ -.CC-HH- CH ₀ OCH ₀ -NHC -C- CH ₀ RR is C ^ alkyl - wherein R is a hydrogen atom or a 0. 7 mass according to claim 6, characterized that the ethylene-like unsaturated monomer N, N'-oxydimethylene bis (acrylamide) is. 8. Composition according to claim 1, characterized in that the ethylene-like unsaturated monomer is a compound of the following formula is: CH ₂ where R is hydrogen or a C, ^{-C ^ -alkyl radical, R 1 is} hydrogen, a C ^ -C ^ -alkyl radical or a phenyl radical, η 1 to 6 and the total number of carbon atoms in - (CHR ¹ ) - is not more than 10 are. 9. Composition according to claim 8, characterized in that that the ethylene-like unsaturated monomer Ν, Ν'-methylene-bis (acrylamide). 309840/1083 0
M. -HH- (CHR ') _n - NH 0
It - C C. H
- C - C R. t
R. 23T1896 10. Composition according to claim 1, characterized in that g e kenn ζ e i chn et, that the ethylene-like unsaturated monomer is a compound of the following formula: 0 .0 CH ₀ - C - C - 0 - (CR ¹ E ") ,, - 0 - C - C -« CH ₀ B ■. R wherein R is hydrogen or a C.-C ^ -alkyl radical, R ^{1 is} hydrogen, a C ₁ -C ₃ -alkyl radical, -OH, -CHgOH or 0
-CH ₀ OC-C = CH ₀ d. \ c. a R "-hydrogen, / C ₁ -C ₃ -alkyl radical, -CH ₂ OH or -CH η is 1 to 6 and the total number of carbon atoms in - (CR ¹ R ") is not more than 11. 11. Composition according to claim 11, characterized in that that the ethylene-like unsaturated monomer is pentaerythritol tetraacrylate. 12. Composition according to claim 1, characterized marked, that the ethylene-like unsaturated monomer is a compound of the following formula: CH ₂ ■ - C - C - ^{O - (CHR 111} CH ₂ O) _n - CC = CH ₂ R R where R is hydrogen or a C.-C ^ alkyl radical, R " ^{1 is} hydrogen or the methyl radical, η 2 to 4 if R" ^{1 is} hydrogen, and 2 to 3 if R " ^{1 is} the methyl radical. 309840/1083 ' 13 mass according to claim 12, characterized in that that the ethylene-like unsaturated monomer tetraethylene glycol dimethacrylate is. 14. Composition according to claim 1, characterized in that the mass is up to 55 wt .-% of an inert, particulate Filler, which is substantially transparent in the mass, contains. 15 photopolymer element, characterized that it comprises a carrier and a layer containing the composition according to claim 1. 16. Photopolymer element according to claim 15 j, characterized in that the composition according to claim 1 containing Layer is a layer forming a height relief. 17- photopolymer element according to claim 16, characterized in that the carrier is a metal and a Layer of antihalation layer material between the metal and the layer forming the height relief is arranged. 18 «photopolymer element according to claim 16, characterized in that the layer up to 55 wt .-% of one inert, particulate filler which is substantially transparent in the layer. marked 19. Method of making a letterpress form / by mixing together the constituents of the mass according to claim 1, heat deformation of the mixture obtained into the form of a film, Layering the film on a carrier to form a photopolymer element, exposing selected surface areas of this element with actinic light to one 309840/1083 substantial cross-linking in the exposed areas occurs without noticeable crosslinking in the unexposed areas and removal of the unexposed areas Areas of the photopolymer mass by washing the photopolymer element with water « 20. The method according to claim 19, characterized in z- ei without t that the heat deformation stage by extrusion molding is carried out. 21. The method according to claim 19? characterized, that the remaining surface water is removed by passing a stream of warm air over the relief. 22. Crosslinked composition, produced by exposing the composition according to claim 1 to actinic light. 23 · Use of the masses according to one of claims 1 to 14-for Production of a photopolymer element, which forms a layer of these masses in a height relief Layer on a support, optionally with the interposition of an antihalation layer. ' 0/1083