DE2120920C3 - Sensitized sheet for pressure-sensitive recording materials - Google Patents

Description

The invention relates to a sensitized Sheets for pressure sensitive recording materials, which is capable of color formation when coming into contact with an essentially colorless color former, ordered from a carrier, with a layer applied thereon, containing a phenolic resin as an acid color reaction component contains.

In the pressure- and heat-sensitive copier papers, such as those in US patents 27 12! 507. 27 30 465, 27 30 457 and 34 18 250 are, microcapsule-containing solutions of a practically colorless organic compound that hereinafter referred to as color former, with electron donating properties and coloring reactivity and an electron attractive adsorbent, hereinafter referred to as a sensitizer is used.

Typical sensitizers are, for example Clays, such as acid clays, active clays, attapulgite, zeolites or bentonites, organic acidic compounds, such as elucinic acid, tannic acid or bile acid and the like.

Recently, a phenolic resin has been used to increase the stabilities of these Sensitizer suggested.

In British patent 10 65 587 the use of an oil-soluble acidic polymer, for example a phenolic resin, together with an acidic material such as attapulgite, as a sensitizer and in Japanese Patent Publication No. 511737, such polymers are, for example Phenolic resins, used as sensitizers. However, although these phenolic resins as sensitizers usually have a distinctive color image, the opposite Water is stable when reacted with a color former, for example crystal violet lactone, benzoyl leucomethylene blue and the like., there are disadvantages that the color image in terms of weatherability what is bad is that it is easily discolored when exposed to sunlight and when left to stand. The object of the invention is to create a sensitized sheet for pressure-sensitive recording materials, that for color formation upon contact with an essentially colorless color former

ίο is capable and made of a carrier with one on it applied layer, which acts as an acid color reaction component contains a phenolic resin, the weather resistance of the sensitizing agent! phenolic resin used is improved.

According to the invention there is provided a sensitized sheet for pressure-sensitive recording materials which is capable of color formation upon contact with an essentially colorless color former, consisting of a carrier with an applied layer containing a phenolic resin as an acid color reaction component contains, created, which is characterized in that this layer also contains an alkali hydroxide or alkali carbonate in an amount of 0.5 to 5 parts per 100 parts of the phenolic resin.

The alkali hydroxide or carbonate is generally used in a solvent such as water, methanol, ethanol and the like. However, when using an oil-soluble phenol halide it can be advantageous to add the alkali metal hydroxide or carbonate to be dissolved in methanol, ethanol and the like.

Examples of suitable alkali hydroxides and carbonates are the hydroxides or carbonates of sodium and potassium.

The phenolic resin solution can be obtained by dissolving the phenolic resin in a solvent such as benzene, Toluene, xylene and the like, the phenolic resins described in the aforementioned GB-PS and Japanese PS, e.g. B. phenol aldehyde resins, phenol acetylene resins and the like.

The above two kinds of solvents are intermediate in terms of quantitative draw the solute and the solvent are not particularly limited as they are after application of the Solutions are dried on a support and evaporated. For the purpose of increasing the ability to absorb Of the phenolic resins, it can also be effective as an adsorbent material, which even when contacted is hardly colored with the color former, for example talc or bauxite or an absorbent Material previously known as a sensitizer, e.g. acid clay, active clay, Attapulgite and the like to be incorporated into the solution of the phenolic resin and the alkaline material.

The activity in the application of these sensitizers is exerted by the alkali hydroxide or alkali carbonate increased, thereby obtaining a valuable pressure-sensitive copier paper that can be used for forming pronounced colorations with high density is suitable. However, the most important thing in the process according to the invention is the weather resistance of the Phenolic resin to enhance color images formed by the alkali hydroxide or alkali carbonate, and a Another advantage is the increase in the activity of the known sensitizers;

The above fact is easily clarified based on the fact that the weather resistance the color image is increased even in the case of adding less coloring adsorbent material to the coating solution.

The practical application of the resulting phenolic resin solution is carried out by individually or together with the microcapsules containing the color former, as indicated below, on one Carrier, such as paper, is mounted.

Another embodiment is also successful with respect to the steps of the previous one Application or coating of the phenolic resin on the carrier and the subsequent mounting of the Solution of the alkali hydroxide or alkali carbonate thereon.

As color formers, crystal violet lactone, beiizoylleucomethylene blue, malachite green lactone, Rhodamine-ß-lactam, 3-dialkylamino-7-dialkylaminofluorane, 3-MethyI-2 \ 2-spirobi- (benzo- [f] -chromen) and other known compounds are used will.

In general, the color formers for the pressure-sensitive copying papers can generally be used as mixtures to complete the instantaneous color formation and the lightfastness of the color image be used.

There are e.g. B. the well-known combination of one High-speed color former, such as crystal violet lactone, as a primary color former with a low speed color former with excellent light resistance, such as benzoyl leucomethylene blue.

However, if the combined color formers are contacted with the phenolic resin and pressed, the crystal violet lactone rapidly forms color on the phenolic resin layer while it takes a long time for the benzoyl leucomethylene blue to color and the color image formed from the crystal violet lactone is easily discolored.

In the case of using a sensitizer according to the invention, the above shortcomings become apparent eliminated, as can be seen from the following examples.

While pressure-sensitive copier papers that form a black color image, by using a Mixture of different color formers, which give different company tints, is produced the pressure-sensitive copier paper according to the invention suitable for forming a pure black image, which is not changed under sunlight.

The usual process for the production of microcapsules containing the color former can according to the in U.S. Patent 2,800,457 be carried out: an embodiment of this is given below:

10 parts of an acid-treated pigskin gelatin and 10 parts of gum arabic were dissolved in 400 parts of water at 40 ⁰ C. After adding 0.2 parts of Turey oil ata emulsifier, 40 parts of the color former oil were emulsified and dispersed therein. The color former oil was prepared by dissolving 2% crystal violet lactone and 1.5% benzoyl leucomethylene blue in an oil composed of 4 parts of chlorinated diphenyl and 1 part of kerosene

After the oil droplets had reached an average particle size of 5 microns, the emulsification was interrupted and ^{water heated to 40 °} C. was added so that 900 parts were obtained with stirring. Here, the temperature must be kept as the Lösurg that it does not fall below 40 ⁰ C. Then the pH of the solution is adjusted to 4.0 4.2 bit stopped by the addition of 10% acetic acid to cause coacervation.

After 20 minutes of stirring the system, the coacervate gels around the oil droplets.

7 parts of 37% formaldehyde were added

when the temperature of the solution reached 20 ° C, and when they reached 10 ⁰ C, the mixture was adjusted to pH 9 adjusted by the careful addition of a 15% aqueous solution of caustic soda.

Then the resulting mixture was heated to 50 ° C with stirring for 20 minutes,
ίο The thus obtained microcapsules were C to 30 ⁰ is unlocked and on a paper of 40 g / m ² in an amount of 6 g / m ^2, based on solids content, raised and then dried

The following examples serve to further illustrate the invention without limiting it.

example 1

A phenolic resin was obtained by the following polymerization:

170 g of p-phenylphenol, 65 g of a 3 "" aqueous

1 VJI! 1101111.! 1JrUIUaUIIg, IUWIl IWJl IÄ.V.11 Il l \ -tt » \ * lt / U j OU-I *. ' acid, 19 g of oxalic anhydride and 40 cm ^{3 of} water were placed in a reactor and refluxed for 10 hours at the boiling point of water Was 130 ° C. The resin was placed in a stainless steel vessel and cooled to obtain the phenolic resin.

10 g of the phenolic resin, dissolved in 40 cm ^J xylene were mixed with 0.1 g of sodium hydroxide dissolved in 10 cm ³ of methanol, mixed, and on a paper of 40 g / m ² in an amount of 5 g / m ^2, based on phenolic resin , applied with a spreading stick and dried.

Comparative example 1

For comparison purposes, a solution of 10 g of the phenolic resin in 50 cm ^{3 of} xylene was applied to the paper of 40 g ^{.n 2} , so that 40 g / m ^{2 of} the phenol was drawn up by means of a draw-up stick, and dried.

Comparison test result '

A capsule sheet with a peeled-on layer of microcapsules containing crystal violet lactone was stacked on each of the sheets according to Example 1 and Comparative Example 1 and ^{pressed with a pressure of 60 kg / cm 2} to develop a pronounced color.

The spectral absorption curves of the color images after one hour were at a wavelength of 700 to 38ϋηιμ determined and the curves of the color images continued after exposure to sunlight determined over 1 hour or 3 hours; the results are shown in FIG. 1 listed.

The spectral absorption curves were determined using an eir.js spectrophotometer.

In FIG. 1 is the product of Example 1 with I and the product of Comparative Example 1 with II, while A is the fresh density, B is the density after exposure to sunlight for one hour and C is the density after exposure to sunlight for 3 hours indicate, these designations being used in the same way in the following examples and comparative examples.

The lightfastness values calculated according to the following equation are given in Table I.

Lightfastness value =

Table I.

Maximum absorption density after exposure to sunlight
fresh density of maximum absorption

Comparative example 2

sunlight
(1 hour)

Sunlight (3 hours)

Example 1 67.1% 60.8%

Comparative example 1 54.5% 48.5%

It turns out that by incorporating the caustic soda in the phenolic resin, the authenticity of the Crystal Violet Lactone is remarkably improved against light according to the table above and from the absorption curve of FIG. 1. that the Change in color tone is reduced.

Further, a sheet coated with microcapsules containing crystal violet lactone and benzoyl leucomethylene blue was piled up on the above sensitizing sheet and pressed with a pressure of 600 kg / cm ² to form a color image. The change in the image density at the maximum absorption (610πιμ) after storage in an interior is shown in Table II.

Table II

Days during the
Storage in one
space

example 1

Comparative example t

OTage

5 days

10 days

20 days

0.750
0.680
0.630
0.560

0.747
0.510
0.470
0.430

As in the case of a sensitized sheet containing no caustic soda, the formed color image of crystal violet lactone was noticeably discolored on storage for 5 days under room conditions, and the benzylleucomethylene blue after storage in was not discolored in a room for 5 days, the color image faded remarkably after 5 days. On the other hand, in the case of a sensitized sheet with the caustic soda, there was discoloration of the crystal violet lactone difficult, and therefore the density of the color image was not lowered after storage for 5 days.

From the above values, it can be seen that the disadvantages of Comparative Examples 1 by the inventive Procedures were remarkably improved.

Example 2

To a dispersion of 10 g of talc dispersed in 40 cm ^{3 of} xylene, 10 g of the same gradually became

Phenolic resin as in Example 1, dissolved in 50 cm ^{3 of} xylene, was added with stirring to produce the paint. The paint was applied to a paper of 40 g / m ³ in an amount of 10 g / m ² , based on the solids content, by means of a spreading stick and

dried

Comparative test result 2

The experiment was carried out in the same manner as in Comparative Experiment Result 1 and the absorption curve of the color image after exposure to sunlight in the same spectrophotometer as determined above, which is reproduced in Fig.2 is. The light fastness value is given in Table III.

25th

Table III

45

50

sunlight
(1 hour)

Sunlight (J hours)

Example 2 66.4% 56.5%

Comparative example 2 473% 38.5%

As in the case of Comparative Test Result 1, it was found in the above results found that the fastness to light of crystal violet lactone was remarkably improved.

Further, a sheet coated with microcapsules containing crystal violet lactone and benzoyl leucomethylene blue was piled up on the above sensitized sheet and printed with a pressure of 600 kg / cm ² to form the color image.

The change in the image density at the maximum absorption (610 ιτιμ) after storage under room conditions can be found in Table IV.

table IV

Days of storage
in the room

Example 2

Comparative example 2

OTage 1.003 0.995 5 days 0.910 0.860 10 days 0.850 0.590 20 days 0.780 0.530

As with comparative test result 1, the effect of the incorporation of the caustic potassium into the results Phenolic resin clearly.

To a dispersion of 10 g of talc, dispersed in 40 cm ^{3 of} xylene, 10 g of the same phenolic resin as in Example 1, dissolved in 40 cm ^{3 of} xylene, were gradually added with stirring

Then 0.2 g of caustic potash, dissolved in 20 cm ^{3 of} methanol, were gradually added to produce the

t »!« $ «■ iH.iw uühvuvluw κ * -νϊ *» ιϊΰνΐ ivil Ii u> U ^ UUl Witt V UL / ld of 40 g / m ² in an amount of 10 g / m ² , based on the solids content pulled up by means of a spreading stick and dried

60

Example 3

To 0.2 g of caustic soda, dissolved in 40 cm ^{3 of} water, 10 g of acidic clay were added and gradually a solution of the same phenolic resin as in Example 1, dissolved in 50 cm ^{3 of} the mixed solvent xylene / methyl alcohol! (!:!), with a stirrer, added to the system. Finally, a styrene-butadiene rubber latex was added in an amount of 4 g based on the solid content to prepare the application solution.

The solution was applied to a paper of 40 g / m ² in an amount of 8 g / m ² , based on the solids content, by means of a coating stick and dried.

Comparative example 3

10 g of acid clay were gradually added to 50 cm ^{3 of} water while stirring and then gradually mixed with 10 g of the same phenolic resin as in Example 1, dissolved in a mixed solvent of xylene / methanol (1: 1).

Eventually it became a styrene-butadiene rubber latex in an amount of 4 g, based on the solids content, added to prepare the solution

The solution was applied to a paper of 40 g / m ² in an amount of 8 g / m ² , based on the solids content, using a spreading stick and dried.

Comparative test results 3

The test was carried out in the same manner as in Comparative Test Result I, and the Results are shown in Figure 3 and Table V. brought.

Table V

sunlight
(1 hour)

Sunlight (3 hours)

Example 3 61.5% 48.5%

Comparative example 3 47.3% 39.1%

From the above values, it can be seen that the fastness to light of crystal violet lactone such as in the comparative test results 1 and 2 was remarkably improved.

Further, a sheet coated with microcapsules containing crystal violet lactone and benzoyl leucomethylene blue was piled up on the above sensitized sheet and ^{pressed with a pressure of 600 kg / cm 2} to form the color image. The change in the image density at the maximum absorption (610 ιτιμ) after storage under room conditions is shown in Table VI.

Table VI

Days storage in
a room

Example 3

Comparative example 3

0 days

5 days

10 days

20 days

1.26
1.12
0360
0.910

1.02
0.780
0.710
0.65

The same effects as Comparative Experiment Result 1 could be obtained.
, A sheet covered in microcapsules containing a compound according to the formula

contained, was sensitized on the above nectar * «es'a ^ gij and with a pressure of 600 k ^ / cjy. ² pressed to form an image.

The spectral absorption curve c of the test piece Mach One hour was determined, and then that of the test piece after exposure to sunlight for 1 hour or 3 hours; the results are shown in FIG.

From the spectral absorption curves, it was confirmed that the maximum absorption is according to Example 3 of initially 600 ιτιμ to 590 ιτιμ on exposure Sunlight for 1 hour and continue on

jo 580 ηιμ when exposed to sunlight during 3 Hours changed.

However, in the sensitizing sheet according to Comparative Example 3, the maximum absorption changed From initially 600 Γπμ to 570 on exposure

Jj sunlight for 1 hour and continued to 560 Γπμ when exposed to sunlight for 3 Hours.

The compound according to the formula

so showed little change in tint in that sensitized sheet according to Example 3.

For this purpose 4 sheets of drawings

Claims (3)

Patent claims: 1. Sensitized sheet for pressure sensitive Recording materials capable of forming color on contact with an essentially colorless Color former is capable, consisting of a carrier with a layer applied thereon, which is a Contains phenolic resin as an acid color reaction component, characterized in that this layer also includes an alkali hydroxide or alkali carbonate in an amount of 0.5 to 5 parts contains on 100 parts of the phenolic resin. 2. Modification of the sensitized sheet after Claim t with a carrier and a phenolic resin applied thereon as an acid color reaction component containing layer, characterized in that it has a further layer with an alkali hydroxide or an alkali carbonate in an amount of 0.5 to 5 parts based on 100 Parts of the f * ßenol resin in the phenolic resin layer, contains. 3. Sensitized sheet according to claim 1 or 2, characterized in that the layer or at least one of the layers also has a further sensitizing agent as an adsorbing substance! or contains a material which when contacted with a substantially colorless Color former does not form any color.