JPS63159082A - Color developer sheet for pressure sensitive paper - Google Patents

Abstract

PURPOSE:To enhance the stability of a developed color image to nitrogen oxide and light, by applying salicylic acid, an alpha,alpha'-dialkoxy-p-xylene and a metallic compound of a specified general formula to a base, thereby producing a color developer sheet. CONSTITUTION:Salicylic acid, an alpha,alpha-dialkoxy-p-xylene and a 1,2,3-or 1,2,4- trialkylbenzene of formula I (wherein each of R1, R2 and R3 is independently an up to 4C alkyl) are brought into reaction at a temperature of at least about 110 deg.C in the presence of a catalyst to obtain a salicylic acid-trialkylbenzene co-condensation resin. An alkali metal salt of the co-condensation resin and a water-soluble multivalent metal salt are brought into reaction with each other in water to obtain a metallic compound, which is used as a color developer. An aqueous suspended liquid of the color developer is prepared, and is applied to a base such as a paper to obtain a color developer sheet for a pressure sensitive paper.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a color developing sheet for pressure-sensitive copying paper, and more specifically, to a color developing sheet for pressure-sensitive copying paper. Developing sheet for pressure-sensitive copying paper used as a coloring agent (prior art) Pressure-sensitive copying paper, also called carbonless paper, develops color under mechanical or impact pressure, such as when writing or using a typewriter. There are copying papers that can make multiple copies, called transfer-type paper, or single-coloring paper.The coloring mechanism is an electron-donating colorless dye and an electron-accepting developer. It is based on a color reaction with a coloring agent. Taking a transfer type pressure-sensitive copying paper as an example, this will be explained as shown in FIG. 1 as follows.

On the back side of the bottom paper 1 and the middle paper 2, microcapsules 4 with a diameter of several microns to more than ten microns are coated with a colorless color-forming pressure-sensitive dye dissolved in non-volatile oil and wrapped in a polymer film such as gelatin. has been done. The surfaces of the middle paper 2 and the bottom paper 3 are coated with a paint containing a color developer 5 which has the property of causing a reaction and color development when it comes into contact with the above-mentioned pressure-sensitive dye. To make a copy, press top - (middle) - (middle)
- If you stack them in the order shown below (the dye-containing coated surface and the developer-containing coated surface face each other) and apply local pressure such as writing pressure 6 or typing pressure, the capsule 4 in that area will break and the pressure-sensitive dye A copy record is obtained by transferring the solution to the color developer 5.

As an electron-accepting color developer, (I) υSP 2,712.
(2) Substituted phenols and diphenols disclosed in Japanese Patent Publication No. 40-9309, (3)
p-substituted phenol-formaldehyde polymer disclosed in Japanese Patent Publication No. 42-20144, (4) Japanese Patent Publication No. 49-1989
Aromatic carboxylic acid metal salts disclosed in Japanese Patent Publication No. 10856 and Japanese Patent Publication No. 52-1327 have been proposed, and some of them have been put into practical use.

The performance conditions that a color developer sheet should have include not only excellent coloring properties that remain unchanged immediately after sheet production and even after long-term storage, but also little yellowing during storage and exposure to sunlight and other radiation, and a color image that is robust and resistant to radiation. Examples include not easily disappearing or discoloring due to water or plasticizers.

Conventionally proposed color developers and sheets coated with them have advantages and disadvantages in terms of performance. For example, inorganic solid acids are inexpensive, but they absorb gas and moisture in the air during storage, resulting in yellowing of the paper surface. p-phenylphenol-novolac resin, which is most commonly used as a p-substituted phenol-formaldehyde polymer, has poor color-forming properties. Although excellent, the coated paper turns yellow when exposed to sunlight or during storage (particularly due to nitrogen oxides in the air), and the colored image fades significantly. Further, although aromatic carboxylic acid metal salts have good coloring properties, yellowing properties, and fading properties due to light, their resistance to water or plasticizers is still not sufficient.

(Problems to be Solved by the Invention) An object of the present invention is to provide a color developer sheet for pressure-sensitive copying paper using a novel color developer that improves the above-mentioned drawbacks.

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

That is, the present invention provides salicylic acid, α, α゛-dialkoxy p
-xylene and the 1,2.3-
or 1.2.4-) A color developing sheet for pressure-sensitive copying paper, characterized in that it contains a metallized co-condensed resin made of realkylbenzene.

The color developer sheet using the novel color developer of the present invention has the same or better color development property than the color developer sheet using an inorganic solid acid or p-phenylphenol novolac resin, and has color development properties. is resistant to fading easily due to water, plasticizers, and light.

Furthermore, yellowing caused by sunlight irradiation is improved, and in particular, resistance to yellowing caused by nitrogen oxides in the air is greatly improved, and it has the advantage of being able to provide a color developing sheet at a low cost that is extremely convenient for handling and storage.

The salicylic acid-dialkylbenzene cocondensation resin used in the present invention is a novel resin that has not been previously produced.

α,α゛-dialkoxy p-xylene, which is an essential component of the cocondensation resin used as a color developer in the present invention, gives a corresponding phenolic resin by reaction with a phenol compound, and this resin can be It is used as a so-called thermosetting polymer composition, which is cured by further reaction with a basic compound (Japanese Patent Publication No. 47-1
5111).

However, these thermosetting polymer compositions use carbolic acid, alkylphenols, phenylphenols, para-aminophenol, pyrogallol, and phloroglycitol as phenolic compounds;
Nothing is known about the reaction with salicylic acid, which means that when a phenol compound and α, α゛-dialkoxy p-xylene are reacted under an acidic catalyst,
Alcohol is produced by the dealcoholization reaction, but when a phenol compound containing an organic carboxylic acid, i.e., salicylic acid, which is a component of the present invention, reacts with the alcohol produced under an acidic catalyst, salicylic acid esters and a mixture of these resins are produced. It is thought that this has not been considered yet because it is easily expected that it would be difficult to obtain the intended target product.

However, the present inventors surprisingly found that when salicylic acid-trialkylbenzene and α,α''-dialkoxy-p-xylene were reacted at a reaction temperature of 110°C or higher in the presence of an acid catalyst, a corresponding esterification reaction occurred. It has been found that the salicylic acid-trialkylbenzene cocondensation resin of the present invention can be obtained with almost no side reactions such as these occurring.

In the present invention, when the reaction is carried out at a temperature of 110°C or higher, when the number of carbon atoms in the alkyl group is 4 or less in various α,α°-dialkoxy p-xylenes, the reaction is rapid and no esterification reaction occurs. , it is easy to obtain a good resin, and the number of carbon atoms is 4, that is, in a butyl group, t
Art-butyl groups tend to react slowly.

Therefore, α, α giving the cocondensation resin used in the present invention
The °-dialkoxy p-xylene is preferably α,α゛-dimethoxy p-xylene, α,αゝ-jetoxy p-xylene, α,α゛-di-n-propoxy p-xylene, α,α9-isopropoxylene. Poxy p-xylene, α, αゝ-di-n-butoxy p-xylene
α・α゛-di-5ec-butoxyp-xylene, α,
Examples include α°-diisobutyl-p-xylene,
It is not limited to these.

The amount of α,α9-dialkoxy p-xylene to be used is 0.1 to 1.0 molar ratio, preferably 0.3 to 0.8 molar ratio to 1 mole of the combination of two components of salicylic acid and trialkylbenzene. .

The trialkylbenzene used to provide the cocondensation resin used in the present invention is represented by the above general formula (I), and 1,2
．． It has an alkyl group at the 3- or 1-, 2-, or 4-position, and these three types of alkyl groups may be the same or different and have 4 or less carbon atoms.

The 1,2,3- or 1,2,4-trialkylbenzene used in the present invention is preferably 1,2,3-trimethylbenzene, 1,2,4-)limethylbenzene,
2.3-dimethylethylbenzene, 2.6-dimethylethylbenzene, 3.4-dimethylethylbenzene, 2.
5-dimethylethylbenzene, 2.4-dimethylethylbenzene, 1,2.3-triethylbenzene, 1.2.
4-) ethylbenzene, 2.3-dimethylisopropylbenzene, 2.3-diethylisopropylbenzene, 2,3-dimethyl-n-propylbenzene, 2.6-
Dimethylisopropylbenzene, 2,6-diethylisopropylbenzene, 3,4-dimethylisopropylbenzene, 3,4-diethyl-1-propylbenzene, 2.
5-dimethylisopropylbenzene, 2.5-diethylisopropylbenzene, 2.4-dimethylisopropylbenzene, 2゜4-diethylisopropylbenzene, 1
, 2.3-triisopropylbenzene, 1.2.4-
) lyisopropylbenzene, 1.2.4- ) two n-
Butylbenzene, 2.3-dimethyl-n-butylbenzene, 3.4-dimethylisobutylbenzene, 3.4-diethyl-n-butylbenzene, 2.3-di-n-butyltoluene, 1.2.4- tri-n-butylbenzene, 2
-ethyl-4-n-butyltoluene, 2-ethyl-3-
These 1.2.3- or 1.
2.4-Trialkylbenzene, even when used alone,
You may use more than one species in combination.

The amount of trialkylbenzene used is 1 salicylic acid.
0.1 to 20 molar ratio to moles, preferably 0.5 to 20
The molar ratio is 10.

These 1.2.3- or 1.2.4-trialkylbenzenes are thought to have similar properties since 1.3.5-)limethylbenzene is difunctional [
Industrial Chemistry Magazine, (4), 626-629 (I962
)).

Due to the ortho and para orientation of the alkyl group and the hyperconjugation of the alkyl group, 1.2.3-trialkylbenzene has the 4th and 6th positions, and 1.2.4-)realkylbenzene has the 3rd and 5th positions, respectively. It is thought to be involved in the condensation reaction. Therefore, the cocondensation resin obtained by the method of the present invention can be considered to have a linear structure.

1.2.3- or 1.2.4-) The purpose of co-condensing realkylbenzene with salicylic acid is to co-condense the non-volatile oil in the microcapsules applied to the back surfaces of the top paper 1 and middle paper 2 in Figure 1. The objective is to improve the compatibility of the metal compound in the co-condensed resin. As a result, the color-developing component quickly reacts with the colorless color-forming dye dissolved in a non-volatile oil, resulting in an instantaneous clear image change.

The reaction temperature for producing the resin used in the present invention needs to be 110°C or higher; if it is lower than 110°C, the reaction will be extremely slow and side reactions such as esterification reactions will be generated significantly. Become. Further, in order to shorten the reaction time as much as possible, the temperature range is preferably about 130 to 240°C, and the zero reaction time is between 1 and 20+1ty. Acid catalysts include inorganic or organic acids, in particular mineral acids, such as hydrochloric acid, phosphoric acid, sulfuric acid or formic acid, or zinc chloride, tin chloride,
Free sol fluorine catalysts such as ferric chloride may be used alone or in combination with organic sulfonic acids such as methanesulfonic acid or p-toluenesulfonic acid.

The amount of catalyst used is salicylic acid, trialkylbenzene,
Approximately 0 of the total weight of α, α9-dialkoxy p-xylene
．． 01 to 5% by weight.

A general method for producing the resin used in the present invention is as follows:
Predetermined amounts of salicylic acid, trialkylbenzene, α, α9
- Dialkoxy p-xylene and a catalyst are added at the same time, the temperature is raised as it is, and the reaction is carried out at a predetermined temperature. As the reaction progresses, the alcohol produced is trapped outside the system. If necessary, trace amounts of alcohol remaining in the system are removed from the thread using nitrogen. After the reaction is completed, the contents are discharged, cooled, and then pulverized to obtain the desired product. If unreacted salicylic acid remains in the resin, methods for removing it include washing the resin with hot water or dissolving the resin in an organic solvent such as benzene, monochlorobenzene, methyl isobutyl ketone, or cyclohexanone and washing with hot water. is taken.

The weight average molecular weight of the cocondensation resin of the present invention is 500 to 300
00 is preferably in the range of 500 to 10,000, and the salicylic acid content, xylene content, and trialkylbenzene content in the resin composition are respectively 5 to 50 mol%, 30 to 50 mol%, and 20 to 65 mol%.

The salicylic acid resin of the present invention has general formulas (If) and (Il
1) (wherein R, , R, and R3 are each independently,
It has a structural unit represented by ), which represents an alkyl group having 4 or less carbon atoms, and the ratio of the structural units (U) and (m) in the resin structure varies depending on the amount of salicylic acid, trialkylbenzene, etc. used.

Several known methods can be applied to produce the metallized product from the salicylic acid cocondensation resin. For example, an alkali metal salt of the resin and a water-soluble polyvalent metal salt are reacted in water or a solvent in which both are soluble. It can be manufactured by

That is, a resin is reacted with an alkali metal hydroxide, carbonate, alkoxide, etc. to form an alkali metal salt of the resin, an aqueous solution thereof, an alcohol solution, or a water-alcohol mixture. This is a method in which ffl is obtained and then reacted with a water-soluble polyvalent metal salt. It is desirable to react about 0.5 to 1 gram equivalent of water-soluble polyvalent metal salt per mole of salicylic acid in the resin.

It can also be produced by mixing a 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 the mixture. In some cases, a basic substance such as ammonium carbonate, ammonium bicarbonate, ammonium acetate, or ammonium benzoate may be further added and melted by heating.

Furthermore, we use resins and polyvalent metal carbonates, oxides, and hydroxides, and combine basic substances such as ammonium formate, ammonium acetate, ammonium caproate, ammonium stearate, and ammonium organic carboxylates such as ammonium benzoate. Can be manufactured by heating and melting.

When producing a metallized resin by heating and melting, the melting temperature is usually 100 to 180"C, and the reaction time depends on the resin composition, melting temperature, type of polyvalent metal salt, and amount used, but The amount of polyvalent metal salt to be used is 1% to about 20% by weight based on the total weight of the resin. It is preferable to use compounds, hydroxides.

There is no particular restriction on the amount of the basic substance used, but it is usually used in an amount of 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 beforehand.

The softening point (JI
Measured using a ring and ball softening point measuring device using S-ni-2548)
The range is 60-150°C.

The metal compound of the salicylic acid-trialkylbenzene cocondensation resin used in the present invention includes metals other than alkali metals such as lithium, sodium, and potassium. Preferred polyvalent metals include magnesium, aluminum, copper, Examples include calcium, zinc, tin, barium, cobalt and nickel. Among these, zinc is particularly effective. These polyvalent metals form metal salts with the intramolecular or intermolecular carboxyl groups of the salicylic acid cocondensation resin.゛The color developer used in the present invention may be used in combination with known color developers, such as inorganic solid acids such as activated clay, organic polymers such as phenol-formaldehyde resin, or metal salts of aromatic carboxylic acids. .

The color developer used in the present invention further comprises at least one of oxides, hydroxides or carbonates of polyvalent metals selected from the group consisting of zinc, magnesium, aluminum, lead, titanium, calcium, cobalt, nickel, manganese and barium. 1
You may use more than one species together.

The method of preparing the color developer sheet for pressure-sensitive copying paper of the present invention includes (I) a method of applying an aqueous paint using an aqueous suspension of a color developer to a support such as paper; Any method can be used, such as a method in which a color developer is strained, and (3) a method in which a solution or suspension of a color developer in a solvent is coated on a support.

When preparing a paint, kaolin clay, calcium carbonate, starch, synthetic and natural latex, etc. are distributed to create a paint with appropriate clay and coating suitability. The proportion of the color developer component in the VI material is 10-7% of the total solid content.
0% is preferable; if the proportion of the color developer component is less than 10%, sufficient color development cannot be achieved, and if it is more than 70%, the paper properties of the color developer sheet deteriorate. The amount of paint applied is 0.5g/r+f or more in terms of dry weight, preferably 1 to 10g/rrl
It is.

In the color developer sheet for pressure-sensitive copying paper of the present invention, the amount of color developer component and paint applied is small, and the concentration, viscosity, etc. of the paint can be changed over a relatively wide range, so on-machine coating, Off-machine coating is also possible, which brings great benefits not only in terms of performance but also in the pressure-sensitive paper manufacturing process.

(Action and Effect) The present invention provides salicylic acid, trialkylbenzene and α,
Provided is a color developer sheet for pressure-sensitive paper containing a metallized product of a novel co-condensed resin consisting of α1-dialkoxy p-xylene as a color developer.

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

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

The performance of the pressure-sensitive copying paper developer sheet was measured as follows.

1. Color development speed and density (conducted in a thermostatic chamber at 20°C and 65χRH) (Commercially available blue coloring paper (Jujo Paper Seisin-40T) containing I1 crystal violet lactone (CVL) as the main pressure-sensitive dye ( 2) Color development using a commercially available black coloring paper (KW-40T manufactured by Jujo Paper Industries) containing 3-diethylamino-6-methyl-7-phenylamino-fluoran (ODB) as the main pressure-sensitive dye and applying a water-based paint. Place the recoated side of the sheet (lower paper) facing each other, and press it with an electronic typewriter to develop the color.

The reflectance was measured at two points, 1 minute 30 seconds after stamping and 24 hours later, using an 880 color difference meter (manufactured by Tokyo Denshoku Kogyo ■).
Display by value.

2. Light fastness of color image The color developing sheet developed using method 1 was exposed to a carbon arc fade meter (manufactured by Suga Test Instruments) for 2 hours (and 4 hours), and the reflectance after irradiation was measured using an 880 color difference meter. and expressed as Y value.

The lower the Y value and the smaller the difference from the pre-test value, the less fading caused by light, which is preferable.

3. Prepare melamine/formaldehyde resin film microcapsules with an average particle size of 5.0 µm containing plasticizer-resistant dioctyl phthalate (DOP) as the core material, and coat the coating solution with a small amount of starch binder using an air knife coater. DOP microcapsule-coated paper is prepared by coating and drying it on paper so that the dry coating amount is 58/d.-txo.

The P microcapsule-coated paper and the coloring surface of the color developing sheet colored in step 1 were placed opposite each other, and then passed through a super calendar roll having a linear pressure of 100 kg/co+ to uniformly infiltrate the coloring surface with DOP.

The reflectance one hour after the test was measured using an 880 colorimeter and expressed 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 colored image. It means that.

4. Water resistance of colored image The color developing sheet developed by the method of 1 was immersed in water for 2 hours, and changes in the density of the colored image were observed with the naked eye.

5. Yellowing of color developer sheet (5-1) Yellowing due to No.
The sample was stored for 1 hour in a sealed container in an NOI gas atmosphere generated by the reaction between sodium nitrite) and uapo* (phosphoric acid), and the degree of yellowing was examined.

One hour after the end of the test, the -B value is displayed using a Σ-80 color difference meter. -B of large WB value and untested sheet
The smaller the difference from the value, the less yellowing under the NOx atmosphere.

(5-2) Yellowing due to light The color developing sheet is irradiated with a carbon arc fade meter (manufactured by Suga Test Instruments) for 4 hours, and after the test, it is displayed as a WB value using a Σ-80 color difference meter. The larger the same value and the smaller the difference from the WB value of the untested sheet, the smaller the yellowing caused by light irradiation.

Salicylic acid, trialkylbenzene, α in the present invention
, αゝ-dialkoxy p-xylene and metallized products thereof were produced according to Synthesis Examples 1 to 13.

Synthesis Example 1 13.8 g (0.1 mol) of salicylic acid was placed in a reactor, 1.
2.4-trimethylbenzene 36.1g (0.3 mol)
α, α°-dimethoxy p-xylene 33.2 g (0,
2 mol) and 0.0 mol of p-toluenesulfonic acid to the catalyst.
2 g and 0.2 g of anhydrous zinc chloride were added. Then, the reaction mixture was heated while stirring and reacted at a temperature of 150 to 160° C. for 4 hours, and 12.0 g of methanol was distilled out. After the reaction was completed, 200 ml of toluene was added to dissolve the reaction composition.

400 d of warm water was added to this, and after stirring for 30 minutes under reflux,
The lower aqueous layer was separated and removed. After repeating this extraction and separation operation of unreacted monomers using 400 d of hot water two more times, 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 was 2380, and the softening point was 81°C when measured using a ring and ball softening point measuring device according to JIS-To 2548.

A tetrahydrofuran solution of the resin was titrated with N/10 sodium carbonate to determine the salicylic acid content in the resin composition.1
It was 4.3% by weight.

Synthesis Examples 2 to 6 Type and amount of trialkylbenzene for salicylic acid,
Synthesis Example 1 was repeated except that the type and amount of α, α°-dialkoxy p-xylene, the type and amount of catalyst, and the reaction conditions were changed as shown in Table 1.
A trialkylbenzene cocondensation resin was obtained.

Synthesis Example 7 10 g of the salicylic acid-1,2,4-trimethylbenzene cocondensation resin obtained in Synthesis Example 1 was placed in a flask and heated to melt at a temperature of 150 to 160°C. Next, add 3.2 g of zinc benzoate and 2 g of ammonium bicarbonate in advance.
．． A mixture of 0 g was gradually added to the molten resin over 30 minutes while stirring. After this, 155-165°
After stirring for 1 hour at a temperature of C to complete the reaction,
After the molten resin was discharged and cooled, it was pulverized to obtain 12.5 g of zincide powder. The softening point of this galvanized product was 98°C.

Synthesis Examples 8 to 12 The same procedure as Synthesis Example 7 was performed except that the metal chloride agent and the type of auxiliary agent were changed for the cocondensation resin of salicylic acid and trialkylbenzene obtained in Synthesis Examples 2 to 6, and the results are shown in Table 2. Various metal chlorides were produced.

Synthesis Example 13 10 g of the salicylic acid-trimethylbenzene cocondensation resin obtained in Synthesis Example 1 was ground 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 while stirring, it was dissolved.

Next, while maintaining the temperature of this solution at 30 to 35°C and stirring, 1.0 g of anhydrous zinc chloride was added in advance to 30 d of water.
was added dropwise over 30 minutes. A white precipitate was deposited, and after continued stirring at the same temperature for 2 hours, it was filtered, washed with water, and dried to obtain 10.4 g of a white powder. This was a zinc salt of salicylic acid-1,2,4-)limethylbenzene cocondensation resin, and the zinc content was 3.7%.

Examples 1 to 7 Using the metallized salicylic acid-trialkylbenzene cocondensation resin obtained in Synthesis Examples 7 to 13 as a color developer, suspensions were prepared by dispersing the following compositions using a sand grinding mill.

Color developer 6 Parts by weight 10χ Polyvinyl alcohol aqueous solution (Kuraray 111?) 3
311 parts water 22.5
Parts by Weight Next, a paint having the following composition was prepared using the suspension.

Suspension 10 parts by weight Light calcium carbonate 10 parts by weight Powder
0.8 parts by weight synthetic rubber latex
0.8 parts by weight water 32.5
Parts by weight These paints are coated on high-quality paper with a dry coating amount of 5.0~
It was coated and dried to give a color developing sheet of 5.5 g/nf.

Examples 8 to 9 Using the developer suspensions obtained in Synthesis Examples 7 and 13, paints having the following compositions were prepared.

Suspension 10 parts by weight zinc oxide 2 parts by weight calcium carbonate
8 parts by weight powder 0.
8 parts by weight Synthetic rubber latex 0.8 parts by weight Water 32.5 parts by weight These paints were coated on high-quality paper at a dry coating amount of 5.0 to 5.5 g/rrr.
It was coated and dried to obtain a color developing sheet.

Comparative example 1 p-phenylphenol 170g, 80% paraformaldehyde 22.5g, p-)luenesulfonic acid 2
．． 0g and 200g of benzene were charged into a glass reactor, heated while stirring, and heated at 70 to 80°C while distilling the water produced by the reaction out of the system by azeotrope with benzene.
After reacting for 0 hours, add 320 g of IJum aqueous solution and distill off benzene by steam distillation. Next, cool and add dilute sulfuric acid dropwise and collect the precipitated p-phenylphenol formaldehyde polymer by filtration. , washed with water, and dried to obtain 176 g of white powder.

A color developer sheet was obtained using this p-phenylphenol formaldehyde polymer in the same manner as in the example.

Table 3 shows the performance evaluation results of the color developing sheets obtained in Examples 1 to 9 and Comparative Example 1.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of pressure-sensitive copying paper. In FIG. 1, each symbol is as shown. L... Upper layer paper 2... Middle paper 3... Lower paper 4... Microcapsules 5... Color developer 6... Pen pressure patent applicant Mitsui Toatsu Chemical Co., Ltd. Figure 1

Claims (1)

[Claims] 1) Salicylic acid, α,α'-dialkoxyky-p-xylene and general formula (I) ▲There are numerical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1, R_2 and R_3 are each 1,2 independently represents an alkyl group having 4 or less carbon atoms.
, 3- or 1,2,4-trialkylbenzene.