JPS6036952B2 - Capsule-containing pressure-sensitive coloring fiber sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capsule-containing pressure-sensitive color-forming fiber sheet, and more specifically to a capsule-containing pressure-sensitive color-forming fiber sheet in which a color developer is microencapsulated with a melamine-formalin resin. It concerns the seat.

From the background, in the known manufacturing method of capsule-containing pressure-sensitive coloring fiber sheets, it is possible to fix the capsules with cellulose fibers during the paper-making process and make the paper under normal conditions, or to make the paper using a so-called wet-end method. A method of adding capsules alone or a cellulose fiber slurry containing capsules to paper has been adopted. Regarding the encapsulation method of microcapsules used for these and the manufacturing method of capsule-containing sheets, there is an example of capsules using urea-formalin in Japanese Patent Publication No. 44-3495, and a gelatin-gum arabic complex coacervation method of Samurai Publication No. 51-14602. Examples of capsules, etc. are known. In addition to the method of incorporating capsules into a fiber sheet on a paper machine, methods for manufacturing capsule-applied sheets include applying the capsules onto general paper, etc. using a coater, or placing the capsules on the surface of the paper by printing with a printing machine. However, when capsules are made on a paper machine, the capsules are not on the surface of the paper and are protected by cellulose fibers inside, so there is very little chance of capsules breaking during normal handling. There is an inherent advantage. Of course, the advantage of reducing the number of coating steps is important in various industrial respects. Conventional gelatin-gum arabic capsules are widely known and most widely used in carbonless copying paper and other applications, and can be said to be quite excellent in terms of protecting the internal phase.

However, the encapsulation process for this capsule is complicated, and since the membrane is mainly composed of gelatin, the characteristics of the membrane are
It also has a major drawback: poor water resistance. For this reason, when used in a normal papermaking process, there is a corresponding drawback that the microcapsules are destroyed during the drying process. On the other hand, capsules using urea-formalin resin as the pus material are excellent in terms of water resistance, but because they do not use dispersants or emulsifiers (Japanese Patent Publication No. 44-3495), they cannot be made into a desired particle size. However, since it is inferior in terms of protecting the internal phase, for example, when applied to fiber sheets containing capsules, undesirable colored stains are likely to occur during handling, and the film must be made thicker, which is why it is necessary. It has drawbacks such as not being able to sufficiently destroy the capsule at any time.

In addition, as a method using a film material similar to this method,
Encapsulation with a urea-formalin resin described in No. 1-9179 has also become known, but has similar drawbacks.

Another effective microencapsulation method is the interfacial polymerization method (Japanese Patent Publications No. 44-27257, No. 42-771, No. 46-18127, No. 5
0-22507) This method is generally difficult to control the film thickness due to the problem of solubility of monomers or polymers, requires ingenuity in equipment because it uses highly reactive and toxic monomers, and has problems with active hydrogen and Because reactions with water (side reactions, decomposition) occur during emulsification, it is difficult to make the particle size of emulsified particles uniform. Compounds with active hydrogen, such as various compounds useful as color developers. The content of the capsule is limited due to undesired reactions between organic acids and monomers.

It has various drawbacks such as poor heat resistance compared to urea-formalin resin. Due to the inconvenient properties of these capsules, even though the benefits of applying capsules to paper by paper-making are known, it is currently only being put into practical use in extremely limited fields. It is.

In addition, there are many descriptions of high boiling point oils that are widely used in carbonless copying paper, but based on the data on properties and safety (toxicity) for various carbonless papers, especially in Japan, 1-phenyl-1- xylylethane, poly(1
~4) Currently, only two types of propylnaphthalylenes are used industrially. In recent years, phenolic compounds have come to be used as acidic color developers instead of inorganic activated clay.

As the phenol compound, P-substituted phenol resin described in Japanese Patent Publication No. 42-20144, Japanese Patent Publication No. 49-10850
Salicylic acid derivatives and metal salts thereof described in Japanese Patent Publication No. 51-25174 are representative examples, and compared to inorganic color developers,
It has features such as extremely high color developing ability, stable quality, and the ability to form color images that are stable in water. P-phenylphenol resin is commonly used as a color developer, but it has drawbacks such as being prone to yellowing when left indoors and slow color development. In the case of color-forming carbonless paper, problems were found during the course of research, such as when it was incorporated into a fiber sheet along with dye capsules, color fogging could occur.

In order to improve this P-phenylphenol resin, modification with substituted phenol has been considered, for example, in Japanese Patent Publication No. 50-29364.

Although there are some improvements made by this method, there is still little difference in practical use. An object of the present invention is to produce a capsule-containing pressure-sensitive color-forming fiber sheet with little yellowing and rapid color development.

Another object of the present invention is to obtain a capsule-containing pressure-sensitive color-forming fiber sheet which has a deep color and is free from color fog.

The present invention is characterized in that the membrane agent of the microcapsule containing the modified P-phenylphenol resin contained in the pressure-sensitive coloring fiber sheet together with the dye is a melamine/formalin resin.

By dissolving the modified P-phenylphenol resin in a high-boiling point oil for carbonless use and encapsulating it, we are able to eliminate the disadvantages of conventional P-phenylphenol resins such as easy yellowing, slow color development, and color fogging. We were able to improve all of the shortcomings such as the tendency to easily cause problems.

Conventionally, there has been a concept of encapsulating P-phenylphenol resin, for example, but ordinary P-phenylphenol resin does not dissolve very well in the above-mentioned high boiling point oil for carbon, so P-phenylphenol resin Resin capsules have not been obtained practically.

The modified P-phenylphenol resin used in the present invention has the characteristic that it is soluble in the above-mentioned high boiling point oil at a concentration of 40% Wt or more.

The modified P-phenylphenol resin used in the present invention contains 10 kg (by weight) of P-phenylphenol and P-phenylphenol resin.
It is obtained by adding 2.5 parts to 30 parts of alkylphenol and condensing it with formalin under normal conditions under acidic conditions.

Specific examples of P-alkylphenols include P-octylphenol, P-r-butylphenol, P-nonylphenol, and P-sec-butylphenol. The most preferable ratio is 10 parts of P-finylphenol to 1 to 2 parts of P-sec. -Butylphenol.

The amount of formalin relative to phenol is important and needs to be 0.5 to 1 mole per mole of phenol. Considering the effect of this modified resin, that is, regarding yellowing, it is thought that the yellowing of P-phenylphenol is mainly due to air oxidation.
This will be a major improvement as it will be protected from the outside air as a microcapsule.

Conventional methods such as resin modification and ultraviolet absorbers,
The present inventor has found that the effect is much greater than that of adding an antioxidant. Regarding the speed of color development, in the case of conventional powder resins, the high boiling point oil for carbonless resin dissolves the resin and becomes a solution, where the color develops for the first time. In the case of the invention, color development is thought to occur instantaneously because the induction period required for dissolution is zero. As for color fog, since the resin is isolated by microcapsules, there is no problem, and P-phenylphenol resin, which could not be used in the past, can now be used as a color developer for self-coloring fiber sheets. The color developer microcapsules used in the present invention are basically made of a melamine-formalin resin material.

Melamine-formalin resin has better properties than urea resin, such as higher water resistance, higher heat resistance, higher tensile strength and compressive strength, and resistance to chemicals, key acids, and weak alkali. These properties are extremely favorable during the dehydration and drying processes when paper is made with cellulose fibers, and it has been found that capsule destruction during paper making is extremely small and the subsequent protection of the internal phase is excellent. Furthermore, since the melamine-formalin resin capsules of the present invention bond extremely easily with cellulose fibers, it was found that capsule-containing fiber sheets could be easily obtained at a good yield by simply adding them to the same machine as ordinary papermaking fillers. . Urea-formalin resin (initial condensate) is not normally used as a water-proofing agent for paper because it has poor fixation to cellulose fibers, but fixation can be done in the form of cation-modified urea-formalin resin or anion-modified urea-formalin resin. It is well used.

On the other hand, melamine-formalin resin (initial condensate) is easily fixed to cellulose fibers in paper making, so it is even used as a water-proofing agent. It is thought that something similar occurs when it is used as a waist material for capsules, and in fact it can be fixed at a high yield under normal papermaking conditions. The method for producing melamine-formalin capsules of the present invention is disclosed in Japanese Patent Application Laid-Open No. 52-11102, which is filed by the same applicant as the present application.
Specification No. 11624y (title of invention "Microcapsule")
According to the method described in. That is, after dispersing and emulsifying a hydrophobic substance (inner phase) in an acidic aqueous solution of a copolymer containing maleic anhydride as one constituent unit, a melamine-formalin initial condensate is added, and the reaction is carried out under acidic conditions and heating. By doing so, the melamine-formalin resin is formed as a film material. Preferred polymerization conditions include a pH of 4.0 to 6. The temperature is 40°C or higher. The ratio of the internal phase of the capsule to the membrane material can be arbitrarily selected depending on the application, but usually the internal phase is 100% (
5 to 5 parts (weight) of the membrane material is appropriate. Among copolymers containing maleic anhydride as one constituent unit, the most preferred is a styrene-maleic anhydride copolymer. The capsules obtained in this way are filled with the usual filler (
Similarly to clays, etc., it can be easily fixed on cellulose by adding it to the pulse slurry after beating.

In addition to capsules, the pulse slurry contains the usual known additives (sizing agents, furnace water agents, bands, clays, starches and latexes, wetting agents, strength improvers, softeners, hardeners, gums, yield improvers). agent, antifoaming agent) and run it on a regular paper machine (
Paper can be made using fourdrinier, circular wire, twin wire, etc., and other properties can be added by size press or coating if necessary. Usually pulp 10
0.1 to 15 head coloring agent capsules per 0 (weight) part
part (preferably used in the range of 1 to 1 part).The pH' at the time of paper making may be acidic or neutral alkaline, but it may be because the capsule is negatively charged due to the anionic (anhydrous) maleic acid. In particular, it was found that when a cationic additive was added, the fixation of the capsule became almost 100%.The additives used to fix the capsule were polyethyleneimine, (cationically modified) polyamide, (cationically modified) polyamide, Preferable examples include acrylamide, polyacrylamide*polyethyleneimine, or epichlorohydrin adducts thereof, cationic starch, and cationically modified urea resin.The following examples will specifically explain the examples.Example 1 P-phenylphenol After 850 minutes, 150 minutes of Psec-butylphenol, 30 hours of 37% formalin aqueous solution, and 20 hours of oxalic acid as a catalyst were added, and the mixture was allowed to react for 5 hours while heating under reflux, and the mixture was boiled to 130 points and dehydrated.

The resulting resin is slightly brown in color. p. was 80°C.
Example 2P-phenylphenol 950mg, P-se
Example 1 was prepared by adding c-butylphenol for 50 hours, 37% formalin aqueous solution for 288 hours, and oxalic acid as a catalyst for 20 hours.
The resin was made under the conditions of the same machine.

m. p. was 86qo. Comparative Example 1 A white m.p. 100% P-phenylphenol, 286 ml of 37% formalin, and 20 ml of oxalic acid were added and reacted under the same conditions. p. A resin of 8:0 was obtained.

Measurement of solubility A 1:1 (weight ratio) mixture of KMC oil (dipropylnaphthalene manufactured by Kureha Chemical ■) and SAS oil (1-phenyl-1-xylylethane manufactured by Nisseki Chemical ■) was used as a carbonless paper oil for these resins. An experiment was conducted on the solubility of .

The resin and oil were mixed and heated to dissolve, cooled to room temperature, and the dissolved state was observed after 1 day, 2 days, and 3 days.
Example 3 (Manufacture of dye capsules) Crystal violet lactone was added to KMC--113 (Kureha Chemical).
The internal phase oil was prepared by heating and dissolving 190 g of aromatic high boiling point oil, and the internal phase oil was emulsified in 200 g of a 5% aqueous solution of a styrene-hydro-maleic acid copolymer adjusted to pH 5.0.

Melamine 10 days, 37% formalin aqueous solution 25 days, water 1 day
Adjust the pH to 8.5 with NaOH, heat to 6,000, and stir to prepare a melamine-formalin initial condensate. This initial condensate was added to the above emulsion, the pH was adjusted to 5.6, and the pH was adjusted to 70.
1 at °C. Polymerize by heating for an hour, then cool, and adjust the pH to 8.
Set to 0 and end encapsulation. The average particle diameter was 5.0. Example 4 (Production of complexion agent capsule) Example 2
A 5% aqueous solution of styrene-maleic anhydride copolymer was prepared by thermally dissolving head coloring agent resin 40 in KMC-113 (aromatic high-boiling oil manufactured by Kureha Chemical Co., Ltd.) 40 to obtain an internal phase oil and adjusting the pH to 5.4. Emulsify the internal phase oil above 160 ml.

Melamine 10 times, 37% formalin aqueous solution 20 times, water 1 time
Adjust the pH to 9.0 with NaOH, heat to 70qC, and ship to the ocean to create a melamine-formalin initial condensate. This initial condensate was added to the above emulsion, the pH was adjusted to 5.8, and the pH was adjusted to 7.
After heating and polymerizing at 0 CC for 3 hours, the pH was adjusted to 9.
Set to 0 and end encapsulation. The average particle diameter was 6.5. Comparative Example 2 Rose phenylphenol resin (m.p.870) 100
part to 2% styrene maleic anhydride copolymer aqueous solution (PH
8) The 10 base particles were dispersed and ground in a ball mill to an average particle size of 2 to 3 peaks, which was used as a color developer.

Parts by weight of paper blend (dhi) Pulp 100 Dye-containing capsules 5 Color developer resin
5 average clay
5 Rosin 1 Sulfuric acid band 2 Polyacrylamide 0.5 That is, the mouth water level is 40 degrees S. 50 parts of LBKP and sparse part of NBKP5 beaten to R (Shopper Rigler), 5 parts of the dye-containing microcapsules of Example 3 (dry basis)
Add 5 parts of color developer resin and 5 parts of ordinary clay, then add rosin sodium salt, and finally add sulfuric acid band and cation-modified polyacrylamide to reduce the amount of aqueous slurry to about 0.3.
%, and a self-coloring type carbonless coloring sheet was prepared using a normal feed liner paper machine for 55 minutes per day.

Comparative Example 3 (Manufacture of dye urea/formalin resin capsules) Crystal violet lactone was added to KMC-
113100 was heated and dissolved to make internal phase oil, pH 4.0
Styrene-maleic anhydride copolymer 5% aqueous solution 1
Emulsify the above internal phase oil in 50 ml of water.

Urea 15 minutes, 37% formalin aqueous solution 30 minutes, water 150 minutes
The dissolved material was added and reacted at 6000 for 4 hours to complete the encapsulation. The average particle size of the microcapsules was 5.5 mounds. Comparative Example 4 (Production of Head Color Agent Urea/Forma IJ Soresin Capsules) Color Developer Resin 1 of Example 2
Styrene-Maleic anhydride copolymerization 5
Emulsify the above internal phase oil with a 50% aqueous solution.

Urea 15 times, 37% formalin aqueous solution 30 times, water 200 times
In the evening, the solution was added and reacted at 60° C. for 4 hours to complete the encapsulation. The average particle size of the microcapsules was 3.34. Comparative Example 5 In Comparative Example 2, instead of 5 parts of the developer resin, 1 $ part of the mauve agent-containing urea-formalin resin capsule of Comparative Example 4 was added, and the dye capsule was replaced with 5 parts of the urea-formalin resin capsule of Comparative Example 3. using
A capsule-containing pressure-sensitive color-forming woven sheet was prepared in exactly the same manner as in Comparative Example 2 except for the other conditions.

Example 5 Instead of 5 parts of the complexion agent resin in Comparative Example 2, 1 part of the mauve agent-containing microcapsules of Example 4 was added.

A capsule-containing pressure-sensitive coloring fiber sheet was prepared in the same manner as in Comparative Example 2 except for the other conditions. Comparative Data Table-1 The pressure-sensitive color-forming bound sheets produced in Example 5, Comparative Example 2, and Comparative Example 5 were printed using a ribbonless typewriter, and
When the reflectance of the blank area and colored area was determined, the results shown in Table 1 above were obtained.

That is, Example 5 according to the present invention has a high degree of whiteness, and is less likely to decrease in whiteness (yellowing) over time.
Furthermore, the color development speed was also found to be slow, demonstrating the effectiveness of microencapsulating the color developer. On the other hand, as shown in Comparative Example 5, the membrane of the urea-formalin resin capsule is inferior to the membrane of the melamine-formalin resin capsule in terms of heat resistance and acid resistance, and the color developer is microencapsulated. Although the coloring speed was improved by this method, it was found that the coloring power was easily blurred.

Claims (1)

[Scope of Claims] 1. Microcapsules containing a colorless electron-donating dye and microcapsules containing a color developer of an acidic substance that reacts with the colorless electron-donating dye to color the dye are fixed to cellulose fibers. In the pressure-sensitive color-forming fiber sheet obtained by papermaking, a colorless electron-donating dye and a color developer are each microencapsulated in a solution state, and a colorless electron-donating dye microcapsule and a color developer microcapsule are further added. 1. A capsule-containing pressure-sensitive color-forming fiber sheet, characterized in that both film agents are made of melamine-formalin resin, and the color developer is a modified P-phenylphenol resin. 2. The solution of modified P-phenylphenol resin contained in the microcapsules contains 1-phenyl-1-xylylethane and/or polyprobylnaphthalene as a main solvent containing 40% (by weight) or more of modified P-phenylphenol resin. The capsule-containing pressure-sensitive coloring fiber sheet according to claim 1, which is a solution containing a capsule. 3. The modified P-phenylphenol resin contained in the microcapsules is prepared by adding 2.5 to 30 parts of P-alkylphenol to 100 parts (by weight) of P-phenylphenol and formalinizing it under acidic conditions. The capsule-containing pressure-sensitive coloring fiber sheet according to claim 1 or 2, which is a resin condensed with. 4. The capsule-containing pressure-sensitive coloring fiber sheet according to claim 3, wherein the P-alkylphenol is P-sec-butylphenol.