JPH0771866B2 - Color-developing sheet for pressure-sensitive copying paper - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color developing sheet for pressure-sensitive copying paper, and more particularly to a novel salicylic acid-1,3,5-trialkylbenzene co-condensation sheet. The present invention relates to a color developing sheet for pressure-sensitive copying paper, which uses a metallized resin as a color developing agent.

(Prior Art) Pressure-sensitive copying paper is also called carbonless paper, and it is a copying paper that is colored by mechanical or shock pressure such as writing, typewriter, etc., and can make multiple copies at the same time. There is a type, a simple color paper, or the like, and the coloring mechanism is based on a color reaction between an electron-donating colorless dye and an electron-accepting color developer. Taking a transfer type pressure-sensitive copying paper as an example and explaining it with reference to FIG. 1, it is as follows.

On the back side of the upper and middle leaf papers 1 and 2, a colorless color-developing pressure-sensitive dye is dissolved in a non-volatile oil, and a microcapsule 4 having a diameter of several microns to a dozen microns is coated with a polymer film such as gelatin. Has been done. The surface of the middle paper 2 and the lower paper 3 is coated with a coating material containing a color developer 5 which has a property of causing a reaction and a color when contacted with the pressure-sensitive dye. To make a copy, top- (middle)-(middle)
-When the local pressure such as the writing pressure 6 and the typing pressure is applied by laminating the dye-containing coating surface and the color-developing agent-containing coating surface in the following order, the capsule 4 at that portion is broken and the pressure-sensitive dye. The solution is transferred to the developer 5 to obtain a copy record.

As an electron-accepting developer, (1) acid clays disclosed in USP 2,712,507, inorganic solid acids such as attapalguide, (2) substituted phenols and diphenols disclosed in JP-B-40-9309, (3) P-Substituted phenol-formaldehyde polymers disclosed in JP-B-42-20144, (4) JP-B-49-10856 and JP-B-52-1327
Aromatic carboxylic acid metal salts and the like disclosed in, for example, have been proposed and partially put into practical use.

As a performance condition that the color developing sheet should have, excellent color development that does not change immediately after sheet production and after long-term storage, of course, does not cause yellowing at the time of storage and exposure to radiation such as sunlight, and the colored image is robust and radiation, For example, it is not easily lost or discolored by water or a plasticizer.

The conventionally proposed developer and the sheet coated with it have advantages and disadvantages in terms of performance. For example, inorganic solid acids are inexpensive, but when stored, gas in the air and moisture are adsorbed to cause yellowing of the paper surface and deterioration in color development performance, and substituted phenols have insufficient color development and the density of a color image is low. Low. The p-phenylphenol-novolak resin, which is widely used as a p-substituted phenol formaldehyde polymer, has excellent color developability, but the coated paper is exposed to sunlight or stored (especially nitrogen oxides in air). ), And the color image remarkably fades. Further, the aromatic carboxylic acid metal salt is good in color developing property, yellowing property and fading property by light, but it is hard to say that the resistance to water or a plasticizer is still sufficient.

(Problems to be Solved by the Invention) An object of the present invention is to provide a color-developing sheet for pressure-sensitive copying paper, which uses a novel color developer in which the above-mentioned drawbacks are improved.

(Means for Solving Problems) The present inventors have completed the present invention as a result of intensive studies for achieving the above object.

That is, the present invention relates to salicylic acid, α, α′-dialkoxy-
p-xylene and general formula (I) (In the formula, R ₁ , R ₂ and R ₃ represent an alkyl group having 4 or less carbon atoms, and these may be the same or different.) 1,3,5-trialkylbenzene A color-developing sheet for pressure-sensitive copying paper, which contains a metallized product of a co-condensation resin.

The color developing sheet using the novel color developing agent of the present invention has a color developability equal to or higher than that of the color developing sheet using the inorganic solid acid or p-phenylphenol novolac resin, and has a color developing property. The image has such a resistance that it is not easily discolored by water, a plasticizer and light.

Further, yellowing due to sunlight irradiation is also improved, and especially yellowing resistance due to nitrogen oxides in the air is greatly improved, and there is an advantage that a color developing sheet extremely advantageous for handling and storage can be provided at low cost.

The salicylic acid-1,3,5-trialkylbenzene co-condensation resin used in the present invention is a novel resin which has never been produced.

The α, α′-dialkoxy-p-xylene, which is an essential component of the co-condensation resin used as a color developer in the present invention, gives a corresponding phenol resin by a reaction product with a phenol compound, and the resin is hexamethylenetetramine. It is used as a so-called thermosetting type polymerization composition which is further reacted with such a basic compound to be cured (Japanese Patent Publication No. 47-15).
111).

However, in these thermosetting polymerization compositions, as a phenol compound, carboxylic acid, alkylphenols, phenylphenols, para-aminophenol, pyrogallol, phloroglicinol are used, and those reacted with salicylic acid are used. Is not known at all. This means that phenol compounds and α, α'-
When reacting dialkoxy-p-xylene under an acidic catalyst, alcohol is produced by dealcoholation reaction,
With a phenol compound having an organic carboxylic acid, that is, salicylic acid which is one component of the present invention, it is possible to give salicylic acid esters and a mixture of these resins by reaction with an alcohol formed under an acidic catalyst to obtain an intended product. Since it is easily expected to be difficult, it is considered that it has not been considered yet.

However, surprisingly, the present inventors have reacted salicylic acid-1,3,5-trialkylbenzene and α, α′-dialkoxy-p-xylene in the presence of an acid catalyst at a reaction temperature of 110 ° C. or higher. Almost no side reaction such as esterification reaction corresponding to the above occurs, and salicylic acid-1,3,5 of the present invention
It has been found that a trialkylbenzene co-condensation resin is obtained.

In the present invention, when the reaction is carried out at a temperature of 110 ° C. or higher, when the number of carbon atoms of the alkyl group in various α, α′-dialkoxy-p-xylene is 4 or less, the reaction is fast, and the esterification reaction also occurs. It does not happen and a good resin is easily obtained. In addition, when the number of carbon atoms is 4, that is, in the butyl group, te
The reaction of the rt-butyl group tends to be slow.

Therefore, α, which gives the co-condensation resin used in the present invention,
The α'-dialkoxy-p-xylene is preferably α, α'-dimethoxy-p-xylene and α, α'-.
Diethoxy-p-xylene, α, α′-di-n-propoxy-p-xylene, α, α′-isopropoxy-p-
Xylene, α, α′-di-n-butoxy-p-xylene, α, α′-di-sec-butoxy-p-xylene,
Examples thereof include α, α′-diisobutyl-p-xylene, but are not limited thereto.

The amount of α, α'-dialkoxy-p-xylene used is 0.1 to 1.0 mol ratio, preferably 0.3 to 0.8 mol ratio, per mol of salicylic acid and 1,3,5-trialkylbenzene. is there.

The 1,3,5-trialkylbenzene which gives the co-condensation resin used in the present invention is a compound represented by the above general formula (I), and the three kinds of alkyl groups may be the same or different and have 4 or less carbon atoms. is there.

The 1,3,5-trialkylbenzene used in the cocondensation of the present invention is preferably 1,3,5-trimethylbenzene, 1,
3,5-triethylbenzene, 1,3,5-tri-n-propylbenzene, 1,3,5-triisopropylbenzene, 1,3,5-
Tri-n-butylbenzene, 1,3,5-tri-sec-butylbenzene, 3,5-dimethylethylbenzene, 3,5-diethyltoluene, 3,5-di-n-propyltoluene, 3,5-diisopropyl Toluene, 3,5-di-n-butyltoluene, 3,5-di-sec-butyltoluene, 3,5-diisopropylethylbenzene, 3,5-di-n-butylethylbenzene, 3,5-dimethyl-n- Examples include propylbenzene and 3,5-di-n-butylisopropylbenzene.
It is not limited to these. These 1,3,5-trialkylbenzenes may be used alone or in combination of two or more. In addition, it may contain trialkylbenzene which is a positional isomer other than these.

The amount of these trialkylbenzenes used is 1 salicylic acid.
The molar ratio is 0.1 to 20 mol ratio, preferably 0.5 to 10 mol ratio.

These 1,3,5-trialkylbenzenes are considered to have similar properties because 1,3,5-trimethylbenzene is bifunctional [Industrial Chemistry, 65 (4), 626].
~ 629 (1962)]. Therefore, the co-condensed resin obtained by the method of the present invention may be considered to have a linear structure.

The purpose of co-condensing 1,3,5-trialkylbenzenes with salicyl is to provide a non-volatile oil in the microcapsules applied to the back surface of the upper leaf paper 1 and the middle leaf paper 2 in FIG. Is to improve the compatibility of. As a result, the color-developing component rapidly reacts with the colorless color-forming dye dissolved in the non-volatile oil, and a clear image can be obtained instantly.

The reaction temperature for producing the resin used in the present invention is required to be 110 ° C. or higher, and if it is lower than 110 ° C., the reaction becomes extremely slow and side reactions such as esterification reaction are increased. Further, in order to shorten the reaction time as much as possible, a temperature range of about 130 to 240 ° C is desirable. Reaction time is 1
~ 20 hours. As an acid catalyst, an inorganic or organic acid,
In particular, mineral acids such as hydrochloric acid, phosphoric acid, sulfuric acid or formic acid, or Friedel-Crafts catalysts such as zinc chloride, stannic chloride, ferric chloride, methanesulphonic acid or p-toluenesulphonic acid. The organic sulfonic acids may be used alone or in combination. The amount of the catalyst used is about 0.01 to 5% by weight of salicylic acid, 1,3,5-trialkylbenzene and α, α'-dialkoxy-p-xylene based on the total weight.
Is.

As a general method for producing the resin used in the present invention,
A predetermined amount of salicylic acid, 1,3,5-trialkylbenzene,
The α, α′-dialkoxy-p-xylene and the catalyst are added at the same time, and the temperature is raised as it is to react at a predetermined temperature.
The alcohol produced as the reaction proceeds is trapped outside the system. If necessary, a trace amount of alcohol remaining in the system is removed with nitrogen to the outside of the system.

After completion of the reaction, the contents are discharged, cooled and pulverized to obtain the desired product. If unreacted salicylic acid remains in the resin, the method of removing it is to wash the resin with hot water or to dissolve it in an organic solvent such as benzene, toluene, xylene, monochlorobenzene, methyl isobutyl ketone, and cyclohexanone. The method of doing is taken.

The weight average molecular weight of the co-condensed resin of the present invention is in the range of 500 to 30,000, preferably 500 to 10,000, and the salicylic acid content, xylene content and trialkylbenzene content in the resin composition are 5 to 50 mol% and 30 to 50 mol%, respectively. And is 20-65 mol%
Is.

The salicylic acid resin of the present invention has the general formulas (II) and (III) (In the formula, each of R ₁ , R ₂ and R ₃ independently represents an alkyl group having 4 or less carbon atoms.), And the structural unit (I
The ratios of I) and (III) vary depending on the amounts of salicylic acid and trialkylbenzene used.

Several known methods can be applied to produce the metallized product from the salicylic acid co-condensed resin. For example, it can be produced by reacting the alkali metal salt of the present resin with a water-soluble polyvalent metal salt in water or a solvent in which both are soluble.

That is, an alkali metal hydroxide, carbonate, alkoxide, or the like of a resin is reacted with a resin to obtain an alkali metal salt of a resin or an aqueous solution, alcohol solution, or water-alcohol mixed solution thereof, and then a water-soluble polyalcohol. It is a method of producing a valent metal salt by reacting it. It is desirable to react about 0.5 to 1 gram equivalent of water-soluble polyvalent metal salt with respect to 1 mol of salicylic acid in the resin.

Further, the resin can be produced by mixing the resin with a polyvalent metal salt of an organic carboxylic acid such as formic acid, acetic acid, propionic acid, valeric acid, caproic acid, stearic acid or benzoic acid and heating and melting. In some cases, a basic substance such as ammonium carbonate, ammonium bicarbonate, ammonium acetate or ammonium benzoate may be further added and the mixture may be melted by heating.

Furthermore, resin and polyvalent metal carbonates, oxides, and hydroxides are used and heated with basic substances such as ammonium formate, ammonium acetate, ammonium caproate, ammonium stearate, ammonium benzoate, and other organic carboxylates. It can be manufactured by melting.

When producing a metallized resin by heating and melting, the melting temperature is usually 100-180 ℃, the reaction time is the resin composition,
Depending on the melting temperature, the type of polyvalent metal salt, and the amount used, it is about 1 to several hours. Regarding the amount of polyvalent metal salt used,
It is desirable to use organic carboxylates, carbonates, oxides, and hydroxides of polyvalent metals such that the metal is present at 1 wt% to about 20 wt% based on the total weight of the resin.

The amount of the basic substance used is not particularly limited, but is usually 1 to 15% by weight based on the total weight of the resin. When using a basic substance, it is more preferable to mix it with a polyvalent metal salt in advance.

The softening point (JIS
-Measurement with a ring and ball softening point measuring device according to K-2548)
60 to 150 ° C.

The metal of the metallized salicylic acid-1,3,5-trialkylbenzene co-condensed resin used in the present invention is lithium,
Although metals excluding alkali metals such as sodium and potassium are included, preferable polyvalent metals include magnesium, aluminum, copper, calcium, zinc, tin, barium, cobalt and nickel. Of these, zinc is particularly effective. These polyvalent metals form a metal salt with an intramolecular or intermolecular carboxy group of the salicylic acid co-condensed resin.

The developer used in the present invention can be used in combination with a known developer, that is, an inorganic solid acid such as activated clay, an organic polymer such as a phenol-formaldehyde resin, or a metal salt of an aromatic carboxylic acid. .

The color developer used in the present invention is at least an oxide, hydroxide or carbonate of a polyvalent metal selected from the group consisting of zinc, magnesium, aluminum, lead, titanium, calcium, cobalt, nickel, manganese and barium. 1
You may use together with 1 or more types.

The method for preparing the color-developing sheet for pressure-sensitive copying paper of the present invention includes (1) a method of applying an aqueous paint using an aqueous suspension of a color developer to a support such as paper, and (2) a papermaking process. Any of a method such as a method of filtering a developer and a method of (3) a method in which the developer is dissolved or suspended in an organic solvent and applied to a support can be used.

When preparing a paint, kaolin clay, calcium carbonate, starch, synthetic and natural latex, etc. are distributed to obtain a paint having suitable clay and coating suitability. The proportion of the developer component in the paint is preferably 10 to 70% of the total solid content, and if the proportion of the developer component is 10% or less, sufficient color development cannot be exhibited, and if it is 70% or more. The paper surface characteristics of the color developing sheet deteriorate. The coating amount of the coating dry weight 0.5 g / m ² or more, preferably 1 to 10 g / m ^2.

In the color-developing sheet for pressure-sensitive copying paper of the present invention, the amount of the developer component and the coating material required is small, and since the concentration, viscosity, etc. of the coating material can be changed in a relatively wide range, on-machine coating, Both off-machine coatings are possible, which brings great advantages not only in performance but also in the pressure-sensitive paper manufacturing process.

(Functions and Effects) The present invention is a pressure-sensitive paper containing a metallized product of a novel co-condensation resin composed of salicylic acid, 1,3,5-trialkylbenzene and α, α′-dialkoxy-p-xylene as a developer. Providing a developer sheet.

The color-developing sheet of the present invention does not cause yellowing due to light and gases such as nitrogen oxides in the air, has a stable color image with respect to light and a plasticizer, does not cause a decrease in color density, and is water resistant. Since it is also good, long-term storage stability is required, so that it is possible to expand the use to applications that were unsuitable for conventional products, and its practical significance is extremely large.

(Example) Hereinafter, the method of the present invention will be described in detail with reference to Examples.

The method for measuring the performance of the pressure-sensitive copying paper color developing sheet was as follows.

1. Color development speed and density (Implemented in a constant temperature and humidity room at 20 ° C and 65% RH) (1) Commercially available blue coloring top paper with crystal violet lactone (CVL) as the main pressure-sensitive dye (Jujo Paper NW-
40T) (2) Apply a water-based paint using a commercially available black color-developing paper (KW-40T made by Tojo Paper Co., Ltd.) that uses 3-diethylamino-6-methyl-7-phenylamino-fluorane (ODB) as the main pressure-sensitive dye. The coated surface of the developed color sheet (bottom paper) is made to face each other and overlapped, and the pressure is developed by an electronic typewriter.

The reflectance is measured with a Σ80 color difference meter (manufactured by Tokyo Denshoku Industries Co., Ltd.) at two points, 1 minute 30 seconds after stamping and 24 hours after stamping, and displayed as Y value.

2. Lightfastness of color image The color development sheet developed by the method of 1 is exposed to a carbon arc fade meter (manufactured by Suga Test Instruments) for 2 hours (and 4 hours) and the reflectance after irradiation is measured with a Σ80 color difference meter. Display Y value.

The lower the Y value and the smaller the difference from the value before the test, the less brown due to light, which is preferable.

3. Plasticizer resistance Dioctyl phthalate (DOP) is used as a core substance, and melamine-formaldehyde resin film microcapsules with an average particle size of 5.0μ are prepared, and a coating liquid containing a small amount of starch-based binder is applied to high-quality paper with an air knife coater. Dry coating amount is 5g / m
Prepare DOP microcapsule coated paper by coating and drying so that it becomes ² . The DOP microcapsule coated paper and the color development surface of the color development sheet colored in 1 are opposed to each other, and then passed through a super calender roll having a linear pressure of 100 kg / cm to uniformly permeate DOP into the color development surface.

The reflectance one hour after the test is measured with a Σ80 color difference meter and displayed as a Y value. The lower the Y value and the smaller the difference from the pre-test value, the better the plasticizer resistance of the color image.

4. Water resistance of color image The color developing sheet developed by the method 1 was immersed in water for 2 hours, and the density change of the color image was visually observed.

5. Yellowing of the color developing sheet (5-1) Yellowing due to NO _X JIS L-1055 [Based on the nitric oxide gas fastness test method for dyes and dyes, the color developing sheet was changed to NaNO ₂ (sodium nitrite). It is stored for 1 hour in a closed container in a NO _X gas atmosphere generated by the reaction with H ₃ PO ₄ (phosphoric acid), and the degree of yellowing is examined.

One hour after the end of the test, the WB value is displayed using a Σ-80 color difference meter. The larger the WB value and the smaller the difference from the WB value of the untested sheet, the less the yellowing under NO _X atmosphere.

(5-2) Yellowing due to light A carbon arc fade meter (manufactured by Suga Test Instruments Co., Ltd.) was irradiated with a color-developing sheet for 4 hours, and a Σ-80 color difference meter was used after the test.
Display as WB value. WB with large WB value and untested sheet
The smaller the difference from the value, the smaller the yellowing due to light irradiation.

The co-condensation resins of salicylic acid, 1,3,5-trialkylbenzene, α, α′-dialkoxy-p-xylene and metallized products thereof in the present invention were produced by Synthesis Examples 1-26.

Synthesis Example 1 Salicylic acid 13.8 g (0.1 mol), 1,3,5-trimethylbenzene 36.1 g (0.3 mol) α, α'-dimethoxy-
33.2 g (0.2 mol) of p-xylene was charged, and 0.2 g of p-toluenesulfonic acid and 0.2 g of anhydrous zinc chloride were added to the catalyst. Then, the mixture was heated with stirring and reacted at a temperature of 150 to 160 ° C. for 4 hours, and 13.3 g of methanol was distilled. After completion of the reaction, 200 ml of toluene was added to dissolve the reaction composition, 400 ml of warm water was added thereto, and the mixture was stirred under reflux for 30 minutes, and the lower aqueous layer was separated and removed. The extraction and separation operation of the unreacted monomer with 400 ml of warm water was repeated twice more, and the solvent toluene was distilled off under reduced pressure. Then, the molten resin was discharged and cooled to obtain a reddish brown transparent resin. The weight average molecular weight of this resin is 2400, and the softening point is JIS-K
When measured with a ring and ball softening point measuring device according to −2548, 83
It was ℃. The tetrahydrofuran solution of the resin was titrated with N / 10 sodium carbonate to find the salicylic acid content in the resin composition, which was 14.3% by weight.

Synthesis Examples 2 to 12 With respect to salicylic acid, the type and amount of 1,3,5-trialkylbenzene, the type and amount of α, α′-dialkoxy-p-xylene, the type and amount of catalyst, and the reaction conditions are shown in Table 1. The procedure of Synthesis Example 1 was repeated except that the above procedure was carried out to obtain various salicylic acid-1,3,5-trialkylbenzene co-condensed resins shown in Table 1.

Synthesis Example 13 10 g of salicylic acid-1,3,5-trimethylbenzene co-condensation resin obtained in Synthesis Example 1 was placed in a flask and heated to 150
Melted at a temperature of ~ 160 ° C. Then, a mixture of 3.2 g of zinc benzoate and 2.0 g of ammonium bicarbonate in advance was gradually added to the molten resin with stirring over 30 minutes. Then, the reaction was terminated by stirring at a temperature of 155-165 ° C for 1 hour. After the reaction was completed, the molten resin was discharged, cooled, and then pulverized to obtain 12.5 g of a zinc oxide powder. The softening point of this zinc oxide was 104 ° C.

Synthesis Examples 14 to 24 Similar to Synthesis Example 13 except that the types of the metal chlorinating agent and the auxiliary agent were changed for the co-condensation resin of salicylic acid and 1,3,5-trialkylbenzene obtained in Synthesis Examples 2 to 12. Then, various metal chlorides shown in Table 2 were produced.

Synthesis Example 25 10 g of salicylic acid-1,3,5-trimethylbenzene co-condensation resin obtained in Synthesis Example 1 was pulverized and dispersed in 100 g of a 0.8% caustic soda aqueous solution. While stirring this dispersion, the temperature
When it was heated to 70 ° C, it dissolved. Next, while maintaining the temperature of this solution at 30 to 35 ° C., a solution of 1.5 g of anhydrous zinc chloride dissolved in 30 ml of water was added dropwise over 30 minutes while stirring. A white precipitate was deposited, and the mixture was stirred at the same temperature for 2 hours, filtered, washed with water and dried to obtain 10.4 g of white powder. This was a zinc salt of a salicylic acid-mesitylene co-condensation resin, and the zinc content was 5.1%.

Synthesis Example 26 10 g of salicylic acid-1,3,5-triethylbenzene co-condensation resin obtained in Synthesis Example 7 was crushed and dispersed in 100 g of an aqueous solution containing 0.5 g of caustic soda. When this dispersion was heated to a temperature of 70 ° C. with stirring, it dissolved. Then, while maintaining the temperature of this solution at 30 to 35 ° C., a solution prepared by dissolving 1.0 g of anhydrous zinc chloride in 30 ml of water was added dropwise over 30 minutes while stirring. A white precipitate was deposited, and the mixture was stirred at the same temperature for 2 hours, filtered, washed with water and dried to give a white powder 10.4.
got g. This was a zinc salt of salicylic acid-1,3,5-triethylbenzene co-condensation resin, and the zinc content was 3.9%.

Examples 1 to 14 Using salicylic acid-1,3,5-trialkylbenzene co-condensation resin metallized compounds obtained in Synthesis Examples 13 to 26 as a developer, dispersed with a sand grinding mill at the following composition.
A suspension was created.

Developer 6 parts by weight 10% aqueous polyvinyl alcohol solution (Kuraray # 117) 3
22.5 parts by weight of water Next, a coating material having the following composition was prepared using the suspension.

Suspension 10 parts by weight Light calcium carbonate 10 parts by weight Starch 0.8 parts by weight Synthetic rubber latex 0.8 parts by weight Water 32.5 parts by weight Applying these paints to high-quality paper at a dry amount of 5.0 to 5.5 g / m ² Application and drying were performed to obtain a color developing sheet.

Examples 15 to 18 Using the suspensions of the color developers obtained in Synthesis Examples 13, 19, 25 and Synthesis Example 26, paints having the following compositions were prepared.

Suspension 10 parts by weight Zinc oxide 2 parts by weight Calcium carbonate 8 parts by weight Starch 0.8 parts by weight Synthetic rubber latex 0.8 parts by weight Water 32.5 parts by weight The coating amount of these paints on high-quality paper when dry is 5.0 to 5.5 g / m ² And dried to obtain a color-developing sheet.

Comparative Example 1 p-phenylphenol 170 g, 80% paraformaldehyde 22.5 g, p-toluenesulfonic acid 2.0 g and benzene 2
00 g is charged in a glass reactor and heated with stirring to distill the water produced by the reaction out of the system by azeotroping with benzene, and react at 70-80 ° C for 2 hours. After the reaction, 320 g of a 10% aqueous sodium hydroxide solution was added, and benzene was distilled off by steam distillation. Then, the mixture was cooled, diluted sulfuric acid was added dropwise, and the precipitated p-phenylphenol formaldehyde polymer was collected by filtration, washed with water and dried to obtain 176 g of a white powder.

Using this p-phenylphenol formaldehyde polymer, a color developing sheet was obtained in the same manner as in the examples.

Table 3 shows the performance evaluation results of the color developing sheets obtained in Examples 1 to 18 and Comparative Example 1.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of pressure-sensitive copying paper. In FIG. 1, the symbols are as follows. 1 ... Top paper, 2 ... Medium paper, 3 ... Bottom paper 4 ... Microcapsule, 5 ... Developer 6 ... Writing pressure

Claims (1)

[Claims] 1. Salicylic acid, α, α′-dialkoxy-p
-Xylene and the general formula (I) (In the formula, R ₁ , R ₂ and R ₃ represent an alkyl group having 4 or less carbon atoms, and these may be the same or different.) 1,3,5-trialkylbenzene A color-developing sheet for pressure-sensitive copying paper, which contains a metallized product of a co-condensation resin.