DE2439429A1 - LIGHT SENSITIVE POLYMER MATERIALS AND THEIR USE FOR THE PRODUCTION OF PRINTING FORMS - Google Patents

Description

Photosensitive polymer compositions and their use for Production of printing forms

Addendum to patent (patent application P 23 11 '896.9)

The patent (patent application P 23 11 896.9 concerns

a photosensitive polymer mass, which is characterized by that they are a cold water soluble, thermoplastic hydroxypropyl cellulose with an MS value of at least 2, from 0.5 "to 25% by weight, based on the hydroxypropyl cellulose, an ethylene-like unsaturated monomer, the unsaturation of which in the form of at least 2

= C - CO residues,

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

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and from 0.5 to 10% by weight, based on the hydroxypropyl cellulose, of a ^{photoinitiator which is thermally stable at temperatures up to 180 °} C., as well as the use of these compositions for the production of a photopolymer element. . -

As described in the main application, these photopolymer compositions from solutions on a suitable support such as granulated aluminum or steel plates or be poured onto polyester film.

In the main application it is stated that in this procedure a methanolic or aqueous solution is added to the solution the hydroxypropyl cellulose in concentrations of 5 to 20 wt .-% prepared and the ethylene-type unsaturated monomers and the photoinitiator can be added.

It has now been found that in addition to the solvents mentioned in the main application, water and methanol, other solvents can be used for this purpose, namely ethanol, formic acid, acetic acid, dimethyl sulfoxide, dimethylformamide, Ethylene chlorohydrin, chloroform, pyridine and a methylene chloride-methanol mixture, which contains 10% by volume of methanol.

As described in the main application, this solution can then poured onto the carrier, spread on its surface with the help of a doctor blade and then evaporate the solvent be left. Films with a thickness of 0.076 mm or more can be conveniently made in this manner.

As described in the main application, the hydroxypropyl cellulose, which is the major organic component of the photopolymer composition of the invention, at least two -Bound propylene oxide molecules (MS value = 2) per anhydroglucose unit and preferably 3 to 5 and more, particularly preferred

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3.2 to 4.0 attached propylene oxide molecules. When the registers can be made using the preferred heat deformation technique, particularly if 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. Preferred materials for making letterpress plates however, forms are those with a molecular weight in the range of about 25,000 to about 200,000 owing the easier etching off or washing away of the unexposed areas with water. The hydroxypropyl cellulose can as described in U.S. Patents 3,278,520 and 3,278,521 described method are produced. This hydroxypropyl cellulose can to some extent be replaced by others Substituents are modified. 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 during the Contribute to the development stage. Also a modification by Allyl residues (DS = 0.01 to 0.5) can be used to form a somewhat more densely crosslinked system.

It has now been found that a modification by tertiary aminoalkyl radicals (DS = 0.01 to 1.0) can also be used for reduction the exposure time of the photopolymer mass and to reduce it the amount of time required to etch away the unexposed areas may, apparently, be beneficial attributed to the greater solubility of the modified hydroxypropyl cellulose in water, especially when acidified is. The modification with aminoalkyl radicals continues to give greater thermoplasticity of hydroxypropyl cellulose, whereby the heat deformation operations are facilitated.

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Mixtures of hydroxypropyl cellulose modified with aminoalkyl radicals and unmodified hydroxypropyl cellulose, which contain only 30% of the modified material, also show the aforementioned advantageous properties.

Suitable modifications with tertiary aminoalkyl radicals are those in the applicant's US Pat. Nos. 3,357,971 and 3,431,254 connections described. The tertiary aminoalkyl radicals, which are described in US Pat. No. 3,357,971 are dialkylaminoalkyl radicals such as dimethylaminoethyl, Diethylaminoethyl, dimethylaminoisopropyl and ethylmethylaminoethyl radicals.

The products of U.S. Patent 3,357,971 are those in which have reacted some of the cellulose hydroxyl radicals with propylene oxide and others with a dialkylaminoalkyl halide implemented. A modified cellulose therefore has the following simplified structure, the modification with Aminoalkyl residues took place through dialkylaminoalkyl residues:

0 OH 0 R ₁

CH _n -CH-CH, (CH ₀ ) -N

EAR

The tertiary aminoalkyl radicals of U.S. Patent 3,431,254 have the following structure:

CH -.- CH-CH _o

OH N-CH-CH-

/ ι ι

R R R

wherein R ₁ and Rp can each be hydrogen or a methyl or ethyl radical, and K, either another

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2-hydroxy-n-propyl radical or a methyl, ethyl, phenethyl, Aminoäthyl-, Cyanoäthyl- or Hydroxyäthylrest can be.

In the process of that US Pat. No. 3,431,254, a more complex one occurs Reaction with the aziridine compounds, of which ethylimine is the simplest representative and this one first is quaternized with propylene oxide, according to the following general scheme:

CH ₀ - CH ₀ + 2 CH ₀ - CH - CH-, + H ₀ O

V ² ^ ² - ³

CH ₀ - CH ₀

OH "+ N - CH ₀ - CH - CH-,

I ² I ³

CH OH CHOH

This gives an intermediate compound A, which then under the basic conditions of the process with some the cellulose hydroxyl radicals reacts, while at the same time the excess propylene oxide with some other cellulose hydroxyl radicals reacts. The product has the following simplified structure:

0 OH 0

1 I.

CH ₀ - CH - CH ₂ CH ₀ CH ₀ - N - CH ₀ CH - CH,

OH <f ^H 2 ^0H

CHOH

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wherein the modification by aminoalkyl radicals from mono- or Di- (2-hydroxypropyl) aminoethyl consists.

Likewise suitable are products which have been produced by hydroxypropylation of cellulose derivatives which contain certain dialkylaminohydroxypropyl substituents. The latter substituents are derived from the corresponding 5-alkylamino-1-halogeno-2-hydroxypropanes, which were prepared by reacting a secondary amine, RpNH, with an epihalohydrin, CH ₀ -CH-CH ₀ X. The reaction can be in a ^N o '

Solvent such as dioxane can be carried out and results in the formation of R ₂ N-CH ₂ -CH-CH ₀ . That formed in the reaction

0
HX is neutralized by excess amine.

The reaction mixture is then acidified with a sufficient amount of acid, HX, to convert the dialkylamino epoxide compound to R ₂ N-CH ₂ -CH-CH ₂ X.
OH

In the foregoing formulas, R usually denotes the methyl or ethyl radical and X is a halogen atom, usually Cl, Br or J.

A typical derivative which was produced by reacting cellulose and R N-CH ₂ -CH-CH ₂ X is 3-diethylamino-OH

2-hydroxypropyl cellulose.

The simplified structural formula of this is with 3-dialkylamino-2-hydroxypropyl modified cellulose is

OH

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In the general formula of the remainder

the substituents can have the following meanings:

η = 2 to 4,

R ₁ = R ₂ = C ₁ -C, -alkyl or -hydroxyalkyl, when η = 2, R ₁ or R _? or both radicals of the hydroxy

be propyl substituent,
if η = 3, the 2-methylene radical can be -QH-, but must

• ^R 3 R ₁ and Rp are alkyl radicals,

if η = 2, both methylene radicals can be -CH-, where R _x = H, '

ι ->

Is methyl or ethyl and one of the substituents R ₁ and R "is 2-hydroxypropyl and the other is 2-hydroxypropyl, methyl, ethyl, phenethyl, airinoethyl, cyanoethyl or hydroxyethyl.

^! .O ■ <;] [> 9/109: ·!

Furthermore, it is stated in the main application that the amount of the photoinitiator in the photopolymer composition according to the invention from 0.5 "to 10% by weight, based on the weight of the cellulose derivative it should be.

It has now been found that the amount of photoinitiator also ranges from 0.1 to about 10 weight percent, and preferably from about 1.0 to about 5.0% by weight, based on the hydroxypropyl cellulose in the photopolymer mass.

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-Vert" 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 the _{same for the alkyl r} , carboxyalkyl or acyl derivatives of cellulose. For the hydroxyalkyl derivatives, the MS value can be greater than 3, since every hydroxyalkyl radical which is introduced into the cellulose molecule provides an additional hydroxyl group which in turn is amenable to hydroxyalkylation. As a result, side chains of considerable length can be formed on the cellulose molecule.

In addition, for details, in particular with regard to the ethylene-like unsaturated monomers and photoinitiators,

on the main patent (patent application P 23 11 896.9)

referenced.

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The invention is illustrated in more detail by means of the following examples.

Example 1 "'

20 grams of glycerol triacetate and 36.0 grams of pigment (trade name Silcron G640, silica with an average particle size of 4 microns from Glidden Pigments) were intimately mixed together. A separate mixture was then prepared by adding together 100.0 g of a hydroxypropylcellulose modified with ethyleneimine (MW = etv / a 150,000, hydroxypropyl-MS = about 3.5, aminoethyl-DS, = about 0.2), 15.0 g of pentaerythritol triacrylate, 0.25 g of dilauryl thiodipropionate and 0.10 g of 2,6-di-tert-butyl-p-cresol were mixed together. The two mixtures were mixed together together with 2.0 g of benzophenone in a Waring mixer, and the mixture obtained was ^{pressed into a cake at 70 °} C. and 42.2 kgf / cm pressure. This cake was placed in a two-roll mill and ^{triturated for 3 minutes at 55 0} C, and the ground material was in the form of a layer with a thickness of 0.635 mn ¹ grained or roughened aluminum supports of 152 178 mm, the thickness of 0.15 mm, molded by pressure.

One of the plates obtained was in strips of 31.8 χ 178 mm cut, and one of these strips was exposed by covering it with a negative and using a 46 cm mercury arc tube lamp (75 W power per 25.4 mm length) in one Distance of 76.2 mm was exposed for 12 seconds. After removing the negative, the exposed strip was with Sprayed water from a nozzle arrangement for 8 minutes. The areas not exposed to light were complete removed, leaving the exposed areas as a relief. After drying in a flow of air, a obtained a satisfactory letterpress plate.

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Example 2

A photopolymer plate was prepared as in Example 1 except that the ethyleneimine modified hydroxypropyl cellulose used had a molecular weight of approximately 500,000. The plate was exposed to light and washed with water as described in Example Λ , whereby a printing plate was obtained.

Example 5

It became a photopolymer plate as in Example 2 with the exception made that 40.0 g of the ethyleneimine modified hydroxypropyl cellulose in conjunction with 60.0 g of a non modified hydroxypropyl cellulose which had a molecular weight of approximately 65,000 were used. the The mass could easily be molded onto an aluminum base and the plate obtained delivered after exposure and washing with water a printing plate with sharp boundaries.

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Claims (8)

Claims 1. Photosensitive polymer mass, this one in cold Water-soluble, thermoplastic hydroxypropyl cellulose with an MS value of at least 2, from 0.5 to 25% by weight, ■ based on the hydroxypropyl cellulose, an ethylene-like unsaturated monomer, its unsaturation in the form of at least 2 CH ₀ = C - CO residues,
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, one thermally at temperatures up to 180 ⁰ C stable photoinitiator contains according to the patent. (Patent application P 23 11 896.9), characterized by ge k e η η, that the hydroxypropyl cellulose is a hydroxypropyl cellulose modified with tertiary aminoalkyl radicals is. 2. photopolymer composition according to claim 1, characterized in that the modified with tertiary aminoalkyl radicals hydroxypropyl cellulose with dimethylaminoethyl, diethylaminoethyl, dimethylaminoisopropyl or ethylmethylaminoethyl radicals is modified. 3. photopolymer composition according to claim 1, characterized in that that the modified with tertiary aminoalkyl radicals hydroxypropyl cellulose with remnants of the following structure CH ₂ -CH-CH ₀ OH N-CH-CH- / I! ^R 3 ^R 1 ^R 2 SU98Ü9 / 1Ö93 2439A29 is substituted in which IL and Rp are each hydrogen or the methyl or ethyl radical and R * is another 2-hydroxy-n-propyl radical or a methyl, ethyl, phenethyl, aminoethyl, cyanoethyl or hydroxylethyl radical. 4. photopolymer composition according to claim 1, characterized in that the modified with tertiary aminoalkyl radicals Hydroxypropyl cellulose is substituted with residues of the following formula: R ₀ N-CH ₀ -CH-CH ₀ -OH wherein R is the methyl or ethyl radical. 5. Modification of the photopolymer composition according to one of the preceding claims, characterized in that the total initiator amount from 0.1 to 10 wt .-%, based on the Hydroxypropyl cellulose in the photopolymer composition. 6. photopolymer composition according to claim 5, characterized in that the amount of photoinitiator is 1.0 to 5.0 wt .-%. 7. Method for producing a letterpress form by mixing together of the components of the mass according to claim 1 by casting from solution according to patent (patent application P 25 11 896.9), characterized in that the solvent Ethanol, formic acid, acetic acid, dimethyl sulfoxide, Dimethylformamide, ethylene chlorohydrin, chloroform, pyridine or a mixture of methylene chloride-methanol containing 10% by volume Contains methanol is used. 8. Use of the photopolymer mass according to one of the claims 1 to 6 for the production of potopolymer elements, v / elche are suitable as printing forms. 5D9809 / 1 093