JPS5841758B2 - record sheet - Google Patents

Description

[Detailed description of the invention] The present invention relates to a recording sheet.

More specifically, the present invention relates to a recording sheet using an improved color developer.

A colorless organic compound (hereinafter referred to as a color former).

), for example malachite green lactone, benzoylleucomethylene blue, crystal violet lactone, rhodamine-B-lactam, 3-dialkylamino-
7-dialkylaminofluorane, 3-methyl-22-
Spirobi (benzo[f]fucurone) and an adsorbent or reactive compound (hereinafter referred to as a color developer) that develops a color when it comes into contact with this color former.

) Recording sheets that utilize the coloring reaction are well known.

Recording sheets that specifically utilize this phenomenon include pressure-sensitive copying paper (for example, U.S. Pat. Nos. 2,505,470, 2,505,489, and 2,550,47).
Specification No. 1, Specification No. 2,548,366, No. 2
, No. 712,507, No. 2,730,456, No. 2,730,457, No. 348
, 250, etc.), and thermal recording paper (for example,
Japanese Patent Publication No. 43-4160, U.S. Patent No. 2,939.
00'A specification, etc.).

Furthermore, a printing method is also known in which a colored image is obtained by supplying ink containing a color former to a sheet coated with a color developer through a medium such as a stencil (German Patent Publication No. 1).
, 939, 624, etc.).

In many cases, the phenomenon of color-forming reaction with the color-forming agent requires pressure, heat, or other physical conditions from a pen, typewriter, or the like.

The most typical form of recording sheet is pressure-sensitive copying paper.

Pressure-sensitive copying paper is produced by dissolving a coloring agent in a solvent such as alkylated naphthalene, alkylated diphenyl, or alkylated diphenylmethane, dispersing it in a binder or incorporating it into microcapsules, and then printing it on paper, plastic, or resin. It is obtained by coating a support such as coated paper.

On the other hand, the color developer is dissolved or dispersed in water or an organic solvent together with the binder, and the solution is applied or impregnated onto the support.

The color developer can also be applied or impregnated as an ink before recording.

Generally, the color former and developer are applied to the same or opposite sides of the support, or to different supports.

The color developer mentioned above generally includes clays such as acid clay, activated clay, attapulgite, zeolite, and bentonite, organic acids such as succinic acid, tannic acid, gallic acid, and phenolic compounds, and acidic polymers such as phenolic resins. It has been known.

Thermosensitive recording paper is obtained by coating a support with a color former and a color developer together with a heat-fusible substance such as acetanilide.

In this case, the thermofusible substance is one that melts with heat and dissolves the coloring agent.

By using a compound with a low melting point as a color developer, it is also possible to make it serve as a thermofusible substance.

The present inventors used the following general formula [
It was previously proposed that a dimer of the compound represented by [I] (hereinafter referred to as alkenylphenol) is effective.

(Here, R1, R2, and R3 each represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and n is 1
represents an integer from 4 to 4.

) That is, by using an alkenylphenol dimer, the various performances of the color developer were substantially improved.

However, the color developing ability and film surface strength of the coating layer were not sufficient, and there was still room for improvement.

Therefore, an object of the present invention is to provide a recording sheet with improved color developing ability and surface strength.

A second object of the present invention is to improve the coating suitability of a coating liquid in order to produce a recording sheet with improved color developing ability and surface strength.

The present inventors have discovered that when preparing a coating solution containing an alkenylphenol dimer, not only the viscosity of the coating solution increases;
The present invention was developed based on the fact that the color developing ability and film surface strength of the final color developer layer do not reach sufficient values due to the aggregation of alkenylphenol in the form of particles.

That is, the above objects are achieved by allowing a surfactant to coexist in a developer coating solution containing an alkenylphenol dimer.

A coating solution containing an alkenylphenol dimer is produced by dissolving or dispersing at least one kind of alkenylphenol dimer in a solvent, but if a surfactant is not added, the viscosity of the prepared coating solution will be lower than that. It increases during the manufacturing process and sometimes makes proper application impossible.

However, if a surfactant is added during or after preparing the coating solution, no increase in viscosity occurs.

The surfactants used in the present invention are funnel oil, alkyl sulfoacetic acid ester salt, higher alcohol sulfate ester salt, alkylbenzene sulfonate, alkyl sulfonate, soap, alkylaryl sulfonate, dialkyl sulfosuccinate, alkylnaphthalene sulfonic acid. Anionic surfactants such as salts, higher alcohol phosphate ester salts, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl sulfonates, dialkyl sulfates, sulfated olefin salts, sulfated fatty acid ester salts; tertiary Cationic surfactants such as amines, ethanolamine ester salts, nonionic surfactants such as glycericimono fatty acid esters, sucrose fatty acid esters; and mixtures thereof; anionic surfactants are particularly effective; Particularly preferred are alkylbenzene sulfonates, higher alcohol sulfate ester salts, naphthalene sulfonate formalin condensates, and alkylnaphthalene sulfonates.

Although the chemical structures of the above-mentioned surfactants are generally not made public, all of them can be easily obtained as commercial products.

The amount of surfactant added is 0.00 parts by weight per 100 parts by weight of the color developer.
The amount is 5 parts by weight or more, preferably 1 to 20 parts by weight.

The coating liquid produced as above is coated with binders such as latex, polyvinyl alcohol, maleic anhydride-styrene copolymer, starch, and gum arabic (solid content).
It can be contained in an amount of 5 to 50 parts by weight per 100 parts by weight.

In addition, the coating solution may further contain acidic resins such as phenol-formalin resin, other color developers such as acid clay and activated clay, inorganic pigments such as metal oxides and metal hydroxides, or chemical or physical treatments thereof. may be added.

An example of a method for synthesizing the alkenylphenol dimer used in the present invention is shown below.

→ Dimerization Mainly dimers (including monomers and oligomers of trimers and higher) The thermal decomposition method is to convert the compound of general formula (It) into alkali or alkaline earth metal oxides, hydroxides, alcoholades,
Alternatively, it can be obtained by thermal decomposition in an anhydrous state in the presence of a phenolate or the like.

Further, dimerization can be obtained by heating at least one compound of general formula [I] to 15-130°C.

Exemplary compounds of general formula [I] [alkenylphenol] used in the present invention include p-impropenylphenol, 2-(p-hydroxyphenyl)2-butene, 2-(p-hydroxyphenyl)-2 −Pentene, α
-(p-hydroxyphenyl)-styrene, 1-(p-
hydroxyphenyl)-1-isobutyne, p-cyclohexenylphenol, 2-(p-hydroxyphenyl)
-3-Methyl-2-butene, 2-(p-hydroxyphenyl)-2-hexene, 2-(p-hydroxyphenyl)-2-hexadecene, m-methyl-p-isopropenylphenol, 2-(o -isopropyl-p-hydroxyphenyl)-2-butene, 2-(o-phenyl-p-
hydroxyphenyl)-2-pentene, 2(o-ter
Examples include compounds such as t-butyl-p-hydroxyphenyl)-2-pentene, m-isopropenylphenol, and 1-(p-hydroxyphenyl)-1-propylene.

These dimers are generally supplied as a mixture of monomers and trimer or higher oligomers, as described above, but the use of such a mixture is not suitable for the purpose of the present invention. There is nothing wrong with that.

The developer coating solution obtained in this manner is coated on a support such as paper, synthetic paper, film, etc. in an amount of 0.1 to 59/rrl, preferably 0.2 to 3 g as the amount of alkenylphenol dimer.
/rIt1 is particularly preferably applied in a range of 0.3 to 297 Wt.

If the coating amount is below the lower limit, sufficient color developing ability will not be obtained, and the upper limit is determined primarily for economic reasons rather than performance.

The recording sheet of the present invention is characterized in that the developer layer contains an alkenylphenol dimer and a surfactant. Conditions such as the type and form of the color former, the type of solvent, etc., can be determined according to the usual technology for recording sheets.

The recording sheet of the present invention has excellent color developing ability because a uniform fine particle or emulsified developer coating liquid can be obtained by the presence of a surfactant, and the thickness of the coating layer can be reduced. Immediately forms a highly concentrated colored image when it comes into contact with a color former.

Furthermore, since the film surface strength is excellent, the film surface (coating layer surface) is stable regardless of before and after use.

Furthermore, in the process of manufacturing the recording sheet of the present invention, the viscosity of the coating liquid does not increase, so coating suitability can be improved, and therefore, not only on-machine size press coating is advantageous, but also air knife coating is easy. become.

These advantages, along with thin layer coating, lead to lower product costs.

Examples will be shown below, and recording scenes of the present invention will be explained in detail.

In addition, the effects in the examples were obtained by using a top paper in which microcapsules containing a coloring agent were manufactured as described below and applied to a support.
This was confirmed using a combination of lower paper coated with the color developer of the present invention on a support.

Microcapsules containing color formers can be manufactured by various known methods, but here they are described in US Pat. No. 2,800,457.
It was produced as follows according to the specification of the patent.

All "parts" below are "parts by weight." 10 parts of acid-treated pork skin gelatin and 10 parts of gum arabic are dissolved in 400 parts of water at 40°C, 0.2 parts of funnel oil is added as an emulsifier, and 40 parts of color former oil is emulsified and dispersed therein.

The color former oil was prepared by dissolving 2% of crystal violet lactone or 3-benzylamino-7-diethylaminofluorane in diisopropylnaphthalene.

Emulsification is stopped when the size of the oil droplets reaches an average of 5 microns.

Add water at 40°C to make a total of 900 parts and continue stirring.

At this time, care must be taken to ensure that the liquid temperature does not drop below 40°C.

Next, 10% acetic acid is added to adjust the pH of the solution to 4.0 to 4.2 to cause coacervation.

Stirring is continued further, and after 20 minutes, the mixture is cooled with ice water to gel the coacervate film deposited around the oil droplets.

When the liquid temperature reaches 20°C, add 7 parts of 37% formalin.

When the temperature reached 10°C, a 15% aqueous solution of caustic soda was added to adjust the pH to 9.

Subsequently, the mixture was heated for 20 minutes while stirring to bring the liquid temperature to 50°C.

After adjusting the microcapsule dispersion thus obtained to 30°C, the solid content was 59/r on a 40/l/d paper.
It was coated and dried to a coating amount of RL to form a capsule sheet.

Examples 1 to 9 40 parts of p-isopropenylphenol dimer synthesized by the method described in JP-A-50-30852 and 2 parts of the surfactant shown in Table 1 were ball milled for 1 day with 58 parts of water. Next, 100 parts of this dimer dispersion, 160 parts of kaolin, and 80 parts of styrene-butadiene copolymer latex (solid content concentration 50%) as a binder were added to 500 parts of water and mixed with sufficient stirring to prepare the present invention. It was used as a coating liquid.

This coating solution was applied to a 509/rrt base paper using a coating rod and dried so that the solid content was 69/d.

Comparative Example 1 A color developer sheet for comparison was obtained in the same manner as in Example 1 except that the surfactant was not used.

Example 10 In Example 1, the dimer of p-isopropenylphenol was converted into the dimer of 2-(p-hydroxyphenyl)2-pentene.
A developer sheet was obtained in the same manner as in Example 1, except that the colorant was replaced with a colorant.

Comparative Example 2 A color developer sheet for comparison was obtained in the same manner as in Example 10 except that the surfactant was not used.

Example 11 25 parts of p-isopropenylphenol dimer was added to 1
Dissolve in 200 parts of 0% soluble soda solution, add 50 parts of activated clay, and stir vigorously.

Add styrene-butadiene copolymer latex 3 to this dispersion.
0 parts of sodium naphthalene sulfonate were added, and 2 parts of formalin condensate of sodium naphthalene sulfonate were further added and thoroughly stirred to obtain a coating liquid.

The obtained coating liquid was applied and dried in the same manner as in Example 1.

Comparative Example 3 A color developer sheet for comparison was obtained in the same manner as in Example 11 except that the surfactant was not used.

Comparative Test Results A microcapsule sheet containing crystal violet lactone or 3-benzylamino-7-diethylaminofluorane was layered on the sheet coated with the color developer of Examples 1 to 11 and Comparative Examples 1 to 3, and the result was 600 KP. Color was developed under a load pressure of /m.

After leaving it in a dark place for a day and night, the reflection spectrum was measured at a wavelength of 380 to 7007 rLμ using a Beckman spectrophotometer DB type, and the absorbance at the absorption maximum is shown in Table 1 as the color density.

Further, the viscosity of the coating liquids of Examples 1 to 5 and Comparative Examples 1 to 5 was measured and shown in Table 1.

The measurement was performed using a BL type viscometer (60 rpm).

It was also confirmed that the surface strength of the film was sufficiently improved by adding the surfactant.

Furthermore, the other properties required for a recording sheet, such as the light resistance and moisture resistance of the color former, were also comparable.

The above comparative test results show that the present invention provides a recording sheet with excellent color developing ability and film surface strength.

Furthermore, the viscosity of the coating liquid can be kept low, which has great advantages in manufacturing, and it is possible to reduce manufacturing costs.

Claims (1)

[Scope of Claims] 1. A color developer layer that forms a color image by contacting a color former is provided on a support, and the color developer layer is a compound represented by the general formula CI) as a color developer. A recording sheet comprising a dimer of and a surfactant. (Here, R1, R2, Rs each represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and n is 1
represents an integer from 4 to 4. )