DE2631832A1 - Pressure sensitive self-contained and carbonless copying materials - contg. formaldehyde! condensate with phenol! (deriv.) as acid acceptor - Google Patents

Abstract

In press. -sensitive recording paper based on microencapsulated couplers (I) and electron acceptor (II), which can be on the same or opposite sides of the sheet, (II) is a low-mol. condensate (IIa) of hydroxybenzene- or hydroxynapthalene-carboxylic acids, phenol and/or substd. phenols and HCHO, opt. in conjunction with salts (IIb) of Gp. (II) or earth metals. (IIa) pref. has an av. mol. wt. of 300-1200, and is esp. derived from (mixts.) of phenols opt. with 1-2 1-12C alkyl, Cl or Br or one Ph or (hydroxy)phenylsuphony substit., and opt. salicylic acid (III). (IIa) can be applied easily, are completely insensitive to atmos. humidity and stable even on prolonged storage in the warm. They give light-fast intense colours of high density.

Description

BASF Aktiengesellschaft 2631832

Our reference: OZ J> 2 090 Moe / Kl 67OO Ludwigshafen, I2.O7.I976

Pressure sensitive recording papers

The invention relates to pressure-sensitive recording papers which, as acceptors, have low molecular weight condensation products of (Alkyl) phenols and / or hydroxyarylsulfones with hydroxyarylcarboxylic acids and formaldehyde.

Carbon paper-free pressure-sensitive recording materials are coated with microcapsules on the back of the sheets, which contain a solution and / or suspension of a color former. The tops of the backing sheets contain one or more acceptors, on which the color former after destruction the microcapsules, e.g. when writing, is adsorbed and converted into a colored compound.

The acceptor and the microcapsules containing the color former can also be applied to the top of the sheets.

As color formers e.g. crystal violet lactone, M-benzoyl leucomethylene blue, Malachite green lactone, rhodamine lactone, Spiropyrans, spirodipyrans or fluorane derivatives are possible. Suitable color formers are e.g. in DT-OS 24 22 899,

20 25 171, 23 18 403, 23 23 803, the DT-AS 21 56 214, the

DT-PS 22 45 504 and 22 30 225 and GB-PS 14 17 695 described.

Acceptors are e.g. attapulgite, activated clays, aluminum oxide, Bentonite, Silton clays, kaolin and other inorganic Connections used.

From US-PS 3,322,557 and 3,488,207 it is known solid aromatic To use carboxylic acids as aeceptors. In the DT-OS

21 52 765 are salts of aromatic carboxylic acids with polybasic Metals recommended, e.g. magnesium, zinc, calcium, cadmium or aluminum salts of benzoic acid, salicylic acid or β-hydroxynaphthoic acid.

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709883/0408

From DT-PS 22 52 901 and 23 03 405 is the use of mixtures of clays, clay and aromatic carboxylic acids and / or known from their metal salts as acceptors.

In the DT-AS 22 42 250, the BE-PS 784 913 and 802 914 are Metal salts of substituted hydroxyary! Carboxylic acids, e.g. of salicylic acid as acceptors.

DT-OS 2 3 48 639 also discloses mixtures of aromatic compounds Carboxylic acids or their salts with polymers are known for the same purpose. If necessary, the mixture can also contain inorganic oxides, clays or clay.

The acceptors are initially by mixing and grinding and / or Dispersion is processed into an aqueous dispersion, which is then processed with the help of doctor blades or by printing on the paper surface is applied.

With the known inorganic acceptors one obtains copies or copies which are sensitive to light and moisture are. Since the acceptors generally contain electrolytes and grain-hard agglomerates, in the case of Applying by printing there is a risk that corrosion and abrasion will occur on the clichés.

The aromatic carboxylic acids or their salts are often soluble in water, which is why when the aqueous printing paste is applied some of the acids diffuse into the interior of the leaf, resulting in a lower color-forming capacity and thus a lower one Color density results.

Mixtures of active clay and aromatic carboxylic acids can also - especially when applied in the printing process - a show disadvantageous abrasion behavior. In addition, they work Mixtures corrosive on printing plates. The corrosion is intensified by the metal salts.

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ir

Acceptor masses, which carboxylic acids, high polymers, clays and / or Clay contain are produced according to an elaborate process: grinding, mixing, precipitating and dispersing in order to achieve a homogeneous to obtain a spreadable or printable preparation. When printing on the ready-to-print acceptor compound, abrasion can also occur appear.

The object of the present invention was to find acceptors which can be easily and safely applied to the papers and which the disadvantages of the acceptors described above State of the art do not have.

It has been found that there are excellent pressure-sensitive recording papers on the basis of parbo formers enclosed in microcapsules and electron acceptors, whereby Color former and electron acceptor on the same side or separately from one another on the lower and upper side of the sheet can be located when, as electron acceptors, low molecular weight condensation products from hydroxybenzene or Hydroxynaphthalenecarboxylic acids, phenols and / or substituted phenols and formaldehyde, optionally in the presence of salts of the 2nd group of the periodic table or the earth metals.

The acceptors according to the invention are against atmospheric humidity completely insensitive and resistant even when stored for a long time in the heat. The ones obtained with these acceptors Colorings have a high color intensity and color density at the same time very good lightfastness.

Hydroxybenzene and hydroxynaphthalenecarboxylic acids for the preparation of the electron acceptors according to the invention are e.g. p-hydroxybenzoic acid, cresotinic acid, 2-hydroxynaphthoic acid-3 and preferably salicylic acid.

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In addition to phenol, phenols in which 1 or 2 hydrogen _{atoms are substituted by C 1} to C ₁₂ alkyl, chlorine, bromine or one Η atom by phenyl, phenylsulphonyl or hydroxypheny / sulphonyl can be used as phenol components. in addition to phenol, C _{1 to C 12} alkylphenols, preferably C 1 to C 1 to C 4 alkyl phenols, such as o-, m-, p-cresol, xylenol, p-tert-butylphenol, p -Hexylphenol, p-octylphenol, p-nonylphenol, p-dodecylphenol; 2-phenylphenol, 4-hydroxydiphenyl ^{sulfone, 4,4 f} -dihydroxydiphenyl sulfone.

The acceptors used are preferably condensation products which contain cresol, C ₁ to C «alkylphenols, chlorophenol, 4,4 · -dihydroxydiphenyl sulfone or mixtures of these phenols as phenolic components«

Particularly preferred condensation products are those produced by condensation of p-tert-butylphenyl and salicylic acid with formaldehyde can be obtained.

The ratio of phenol to hydroxycarboxylic acid to formaldehyde is usually 1 to 2: 0.5 to 2: 0.2 to 1 mol. The condensation products have an average molecular weight between 300 and 1200, preferably from 400 to 800. The acid number of the condensation products is preferably between 100 and 200.

The production of such acceptors is e.g. in DT-PS 714 819, 693 770, 1 124 959, 1 495 176, DT-AS 1 217 409 and the DT-OS 23 19 64l.

The acceptors according to the invention are extremely soluble in organic liquids, such as C ₁ to C 6 alkanols, C ₂ to C ^ alkanediols and / or triols, ethylene glycol monoalkyl ethers, aromatic hydrocarbons, esters and / or ketones. Preferred solvents are methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol, 1,2-propanediol, glycerol, acetone, methylethy! Ketone, toluene, xylene or mixtures thereof.

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Of the solvents mentioned are methanol, ethanol, the monoethyl and monomethyl ethers of ethylene glycol or mixtures these solvents because of their particularly high dissolving power and high evaporation rate and ethylene glycol, Using propylene glycol and glycerin as evaporation regulators higher boiling point particularly preferred. In addition, the solvents mentioned are highly compatible with the binders.

Because of their good solubility, the acceptors can advantageously be used in the form of concentrates.

With the condensation products to be used according to the invention (Acceptors) storage-stable concentrates can be produced, which up to 75 Gew. ^, Preferably 40 to 60 Gew. ^, Based on the concentrate (solution), contain condensation product.

For the production of CF sheets, the acceptor is in the form of a Solution, optionally together with binders, applied. It is preferably applied using a printing process such as flexographic or gravure printing. Suitable binders are, for example: fuel-soluble resins such as shellac, ethyl cellulose, styrene-maleic acid resins, Nitrocellulose, also alkyd resins, polyacrylic acid esters, polyamide resins, rosin resins, vinyl chloride-vinyl acetate resins, Cyclanone resins, urea-formaldehyde resins, urea-melamine resins or mixtures of these resins.

The ink may contain 5 to 50 wt.% Of the inventive acceptor and up to 50 wt.% Of one or more binders. Printing inks, the 10 to Uo wt.% Of acceptor (condensation product), 0 to 30 wt.% Binder and 90 to 30 wt.% Are preferably used, of one or more solvents. In addition, the ink may be from 0 to 5 wt.% By weight of a salt of metals of the 2nd group of the periodic system or of the earth metals, for example salts of magnesium, calcium, aluminum or zinc.

The binding agent is used to produce the CF sheets (i.e. the sheets coated with the acceptor) are not absolutely necessary, since one can also use the acceptor solution alone Receives excellent CF sheets.

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ORIGINAL INSPECTED

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The printing inks which contain the acceptors according to the invention, show no corrosion on the matrices and no abrasion during printing.

A great advantage of the acceptors according to the invention lies in the extremely fine distribution, which is caused by the application of a homo'-gen Solution is achieved. Because of the inventive to be used acceptors achievable high Parb intensity, the acceptor only needs a relatively small amount

2 Area concentration of 0.5 to 10, preferably 1 to 5 g / m 2 be applied.

This also results in economic advantages. Another advantage is that the font obtained with the Parbbildnern on the copy has high fastness properties and a long shelf life.

By using concentrates, the acceptors can easily be processed into the corresponding printing inks without grinding and / or dispersing operations as with the known acceptors are required. In addition, is omitted Application of concentrates dusting.

The pressure-sensitive ones according to the invention are used as color formers Recording papers are all known for such purposes, for example those mentioned above. The color formers are preferably used in the form of microcapsules that dissolve the color former in the organic solvent and / or suspended included.

The microcapsules can be prepared by known methods, e.g. by coacervation of gelatin gum arabic, by polycondensation, Polyaddition or by precipitation of dissolved copolymers at the interface between water and core material (DT-OS 21 19 and 22 37 503).

Particularly preferred are microcapsules which, as a core (i.e. as a solvent for the color former), are phthalic acid dialkyl ester, Adipic acid dialky ester, optionally mixed with aromatic

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such as terphenyl and diphenyl. The core material are the di-n-butyl and di-isobutyl esters and the di- 2-ethylhexyl esters of phthalic acid and mixtures of these esters particularly preferred.

With the acceptors according to the invention, pressure-sensitive acceptors can also be used Recording papers are made in which acceptor and color former are together on the same page are applied (so-called "self-contained paper"). In this case, the color former enclosed in microcapsules is applied to the CF layer applied.

The following examples are intended to explain the invention further. The percentages given below relate to that Weight.

example 1

A 20% ethanolic solution of the condensation product (average molecular weight 570) obtained from p-tert-butylphenol, salicylic acid and formaldehyde according to DT-OS 23 19 641, Example 1, was printed on a paper web (basis weight 60 g / m 2). Application: 1.9 g / m. The acceptor sheet obtained serves as a backing sheet for the production of pressure-sensitive recording papers. The support sheet used was coated on the underside (= transmitter side) with microcapsules, which were produced according to the method described in DT-OS 21 19 933. The core material of the microcapsules contained a solution of 4.5 % crystal violet acetone and 1.5 % N-benzoylleuco-methylene blue in dibutyl phthalate. The order on the

2 2

The donor side was 5 g / m 2 microcapsules (dry) and 2 g / m 2 a mixture of cellulose flour and an acrylate-styrene copolymer dispersion. The application was carried out using an air brush.

Writing gives blue copies which remain unchanged even when stored at 100% relative humidity.

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If you use a paper, the Silton-Clay, as the acceptor sheet contains as acceptor, the copy obtained disappears under the same conditions after a few hours.

Even at 70 to 80 % relative humidity, the last-mentioned acceptor sheet shows a rapid removal of the copy.

Example 2

The acceptor was produced according to DT-PS 11 24 959, Example 1 from o-hydroxydiphenyl, salicylic acid and formaldehyde. Average molecular weight 660.

A 15 # solution of the acceptor in ethanol was made using the gravure coating process applied to paper. Order weight: 2.5 g / m.

A paper coated with gelatin microcapsules was used as the donor. The production of the microcapsules was carried out according to US Pat. No. 2,800,457; Application weight 6 g / m capsules. The capsules contained a solution of 3 % crystal violet lactone and 1% N-benzoyl-leukooxazine (GB-PS 1 417 695) in a terphenyl mixture.

Intense blue copies were obtained which are stable even at higher relative atmospheric humidity.

Example 5

The acceptor was produced according to DT-PS 714 819, Example 1 from o-chlorophenol, salicylic acid and formaldehyde. Mid-

Average molecular weight 410. Application on paper: 1.5 g / m from ethanol solution. With the encoder side specified in example 1 intensely blue and permanent copies are obtained.

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Similar results are obtained if the condensation products obtained according to DT-PS 714 819, Examples 4, 6 and 11 are used as the acceptor. The application weights were 2.4, 3.1 and 3.4 g / m ² .

Example 4

The acceptor was prepared according to DT-PS 714 819, Example 11 from o-chlorophenol, formaldehyde and salicylic acid and with the condensation product a 50 # strength ethanol solution produced (stock solution).

The stock solution was diluted to 25% acceptor content by adding ethanol and 10% ethyl cellulose was added to this solution. The resulting solution was printed on paper by gravure printing. The acceptor sheet obtained gives intensely blue and permanent copies with the donor side described in Example 1.

Very similar results are obtained when using the acceptor solution instead of ethyl cellulose the same amount of shellac, styrene-maleic acid resin or cyclohexanone resin is added as a binder will.

Example 5

Acceptor sheets obtained according to Example 3 were used (backing sheet).

Papers were used as support sheets, the underside of which were coated with microcapsules, which are those in the table specified color formers contained. The colors obtained when copying on the acceptor sheets are given in the table.

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Containing microcapsules as color former (P)

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Of

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in solution

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Copy color

a) 3 ^f -Phenyl-7-diethylamino-2.2 ^t -spirodi- (2H-l-benzopyran)

b) 3 ^t -diethylamino-2 ^l -dibutylamino-8'-methyl-5 ', 7'-diaza-spiro (phthalone-l, 9'-χanthene)

c) 2,6-diphenyl-4- (i | ^f -dimethylaminopheny1) pyridine

blue

Red

yellow

d) Mixture of a)
b)
and c) Hi black e) 2-n-octylamino-6-diethyl
aminofluoran green f) 3-ethylamino-6-chlorofluorane orange

All copies remain unchanged even when stored at high relative humidity.

Example 6

The condensation product used as an acceptor was after DT-OS 23 19 641, example 1 produced.

A 20 # solution of the condensation product in a mixture of 10 % ethylene glycol monoethyl ether and 90 % ethanol was prepared. 0.6 g of zinc chloride (anhydrous) was then added to 100 g of this solution and dissolved. With the solution obtained, receiving sides (“coated front”) were produced by coating paper.

With the encoder sides ("coated back") specified in Example 1, intense blue copies are obtained, which are also used in the Storage at high humidity are stable. In addition, the lightfastness of the copy was improved.

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If magnesium chloride is used instead of zinc chloride, comparable results are obtained. In this case, a mixture of 90 % ethanol and 10 % water is used as a solvent to dissolve the magnesium chloride.

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Claims (3)

ο. ζ. 32,090 claims 1.) Pressure-sensitive recording papers based on color formers enclosed in microcapsules and electron acceptors, where color formers and electron acceptors can be on the same side or separately on the bottom and top of the sheet, characterized in that low molecular weight condensation products of hydroxybenzene as electron acceptors - Or hydroxynaphthalenecarboxylic acids, phenol and / or substituted phenols and formaldehyde, optionally in the presence of salts of the 2nd group of the periodic table or of the earth metals. 2. Recording papers according to claim 1, characterized in that the condensation product has an average molecular weight between 300 and 1200. 3. Recording paper according to claim 1 or 2, characterized in that the electron acceptor by condensation of phenol, phenol in which 1 or 2 hydrogen atoms by C.- to C ₁₂ -alkyl, chlorine, bromine or a hydrogen atom by phenyl, phenylsulfonyl or hydroxyphenylsulfonyl are substituted, or mixtures of these phenols and salicylic acid with formaldehyde is obtained. BASF Aktiengesellschaft 709883/0408 iNSPECTSD