JPS60145881A - Heat-resistant stilt material for pressure-sensitive copying paper - Google Patents

Abstract

PURPOSE:To obtain a stilt material for pressure-sensitive copying paper which shows a high performance, has an excellent heat resistance and is easy to prepare and inexpensive, by forming same of high-amylose corn starch of specified particle size containing a specified quantity of amylose. CONSTITUTION:This is a heat-resistant stilt material for pressure-sensitive copying paper which is formed of high-amylose corn starch of particle size 3-10mu, as a component, obtained by sorting high-amylose corn starch containing 50% or more amylose in a quantity by a sorting method. Starch grains of particle size 3-10mu which is contained about 50% in the high-amylose corn starch have spherical shapes and excellent fluidity, are unbreakable, and have an especially- high gelatinization temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stilt material for pressure-sensitive copying paper, which is made of bias-loose cornstarch and has a particle size of 3 to 10 μm.
The object is to provide a stilt material for pressure-sensitive copying paper that has high performance and excellent heat resistance, is easy to manufacture, and is inexpensive.

Since pressure-sensitive copying paper was developed as a method of copying and recording to replace wax carbon paper, it has rapidly become popular as it is convenient and suitable for streamlining office processing.

Pressure-sensitive recording paper is made up of three sheets of paper, and the back side of the top paper contains microcapsules of 3 to 15μ containing an oil in which a coloring agent called KFi colorless leuco dye is dissolved, and the capsules also have a slightly smaller particle size. A mixture of other stilt materials, such as starch with a large grain size or finely powdered cellulose, is uniformly applied along with a binder.

A mixture of a color developer that develops color by contacting a leuco dye solution on the surface of the paper Fi in the middle layer, and color developer particles such as acid clay or oil-soluble 7-enol resin of 5 to 20μ is used as latex or water-soluble polymer. It is evenly applied with the binder of
Also, the back side of the paper is coated with microcapsules, similar to the top layer of paper.

The lower layer paper is coated with a color developer in the same way as the surface of the middle layer paper.

Needless to say, the key to the coloring mechanism of pressure-sensitive recording paper lies in the coloring agent, the microcapsules containing the coloring agent, and the coloring agent layer that develops the coloring agent, but in order to make this coloring mechanism appear more effectively, The properties of the stilt material that holds the microcapsules and the developer particles that hold the color developer are important.

In particular, the physical and chemical properties of the particles of the stilt material, such as the size, shape, physical properties of the particle surface, water absorption, oil absorption, and heat resistance, greatly affect the coloring performance.

Currently, the stilt material for pressure-sensitive copying paper that is commonly used is mainly made of untreated # material such as wheat starch, as described in, for example, t#i Special Publication No. 1178/1983. is.

The use and amount of pressure-sensitive copying paper used has been increasing year by year due to the recent development of pressurizers and the spread of on-line systems that connect them to communication lines.

Along with this, expectations regarding the performance of pressure-sensitive copying paper have become increasingly sophisticated and diversified.

One of these is the increasing demand for heat-resistant pressure-sensitive copying paper.

Heat resistance in pressure-sensitive copying paper is required from both the manufacturing and usage standpoints.

One of the reasons why heat resistance is necessary in manufacturing is because of the limited use of heat in the process of applying the inder to the base paper and drying it, resulting in poor performance and productivity. This is to improve the decline.

The reason for the need for heat resistance in terms of use is that hot melt adhesives are used when bundling pressure-sensitive copying paper into notebooks, and when printing and embroidering after copying and mailing. This is to prevent the pressure-sensitive copying paper from being contaminated by the heat it receives.

Due to these demands, heat-resistant microcapsules were first developed (for example, Japanese Patent Publication No. 49-45155).
Next is heat-resistant pressure-sensitive paper! Development of the Am method is underway (for example, Japanese Patent Publication No. 49-26848).

As a result, the microcapsules containing a color former were changed from heat-resistant gelatin to heat-resistant microcapsules made of heat-resistant synthetic polymer.

However, the development of a heat-resistant stilt material that holds heat-resistant microcapsules has been delayed, and the above-mentioned problems have not yet been completely solved.

Furthermore, in recent years there has been an increasing need for high-speed, high-sensitivity, and clear copying of pressure-sensitive copying paper set in large numbers, and countermeasures such as reducing the particle size of microcapsules have been taken, and along with this, the performance of stilt materials has improved. The development of starch-based stilt materials with high performance and heat resistance is now in great demand.

Considering these circumstances, the inventors of the present invention conducted extensive research to develop 1) Il+ powder-based stilt material that has high performance, excellent heat resistance, is easy to manufacture, and is inexpensive. The present invention was completed based on the discovery that 3 to 10 μm of iaamylose cornstarch satisfies this purpose.

That is, 1) the present invention has an amylose content of 50% or more)
This is a heat-resistant stilt material for pressure-sensitive copying paper, which is obtained by dividing I-I loin cornstarch by a classification method and has a particle size of 6 to 10 μm.

When selecting the stilt material, the AI type of starch to be used is selected according to the particle size of the microcapsules.

Rice starch, which has the smallest particle size among starches, is not suitable for this purpose because its particles are not spherical but dice-shaped, so it not only has poor fluidity but also breaks easily and is expensive.
do not have.

The present inventors have thoroughly investigated the properties of starch used as stilt material, and have clarified that it is essential to use heat-resistant starch for heat-resistant stilt material.

Heat-resistant starch does not cause starch or gelatinization even when heated.
It also refers to starch whose starch granules are difficult to break.

Known methods for making starch heat resistant include crosslinking it or coating it with a synthetic resin or the like to make it insoluble.

However, such treatment not only scratches the surface of the starch grains and makes them more likely to break, but also increases the water absorption and oil absorption properties, impairing the fluidity of the starch grains. This is not preferable because the structure becomes synthetic resin-like and the original length nr of natural fa is lost.

The present inventors have discovered that high amylose corn starch with an amylose content of 50% or more, which is produced from Beazuhachisu corn by normal wet milling, has a high gelatinization temperature without such processing. As a result of analyzing the properties of this starch granule, it was found that the particle size is 3 to 10μ, which is about 50X in non-amylose cornstarch.
The powder grains are spherical in shape and have excellent fluidity, making them difficult to break and having a particularly high gelatinization temperature (around 93°C).
In addition, even with high amylose cornstarch, starch granules with a particle size of 10μ or more have a square shape, have poor flowability, are easily broken, and have a low gelatinization temperature (8
He discovered that starch granules obtained by dividing this high amylose corn starch into particles with a particle size of 6 to 10 microns using a classification method have excellent heat resistance.

First, the remaining Il is produced as a by-product by dividing the starch grains! 1
It was also found that F+0 Kaoru's Baiazu loin corn starch has improved suitability for food applications, and as a result, this treatment does not result in a significant increase in cost.

For these reasons, the present invention requires the use of high azerose corn starch obtained by dividing high amylose corn starch by a classification method and having a particle size of 3 to 10 microns. This was the first time that we were able to solve the problems faced by pressure-sensitive copying paper.

In this case, it is possible to use pulverized large-particle starch of high amylose corn starch, but large-particle starch with a particle size of 10μ or more can be crushed to a particle size of 6 to 10μ without gelatinization temperature. The object of the present invention cannot be achieved because the starch grains are low, the shape of the crushed starch grains is not spherical, the fluidity is poor, and the grains are easily broken.

If the heat-resistant stilt material for thermal copying paper of the present invention is used,
(2) The heat limit used in the production of pressure-sensitive copying paper can be increased from the conventional 50°C to 90°C.

■ Heat resistance is imparted to pressure-sensitive copying paper, which prevents contamination caused by heat when using hot melt adhesives.

■ Because it is made of small-particle stilt material that can accommodate the reduction in the particle size of microcapsules, high-speed, high-performance copying is possible due to the properties of the particles.

■ Due to low oil absorption, the color developer in the color developer layer does not migrate.

In addition, since the water absorption is small, no problem arises in terms of moisture resistance.

■ Low-cost pressure-sensitive copying paper can be provided because it is inexpensive and can be supplied in large quantities.

It has the following effects.

Next, examples of the present invention will be shown.

Example 1 40 parts of diimpurpyrubiphenyl and chlorination degree of 20% by weight
, 3- to 10 parts of chlorinated normal paraffin having 14 carbon atoms
Dissolve 4 parts of diethyl alcohol, 7-dibenzylaminofuran, 10 parts of toluylene diincyanate,
A solution consisting of 6 parts of bisphenol, 5 parts of lead alpha octylate, and 20 parts of methylene chloride was mixed to prepare a -2 solution.

10 parts of gum arabic was dissolved in 40 parts of water at 30 DEG C., and the above primary solution was added thereto and emulsified using a homogenizer to form an oil-in-water dust emulsion having a diameter of 6 to 10 microns.

The emulsion was poured into 40 parts of hot water at 50°C, and the temperature of the system was raised to 80°C while stirring, and this temperature was maintained for 30 minutes to form capsules.

On the other hand, high amylose cornstarch with an amylose content of 70% was processed using an air classifier (manufactured by Nisshin Engineering KK, T
o-4ONW machine) and divided into two parts with a grain size of 10μ as a boundary to obtain high amylose cornstarch in the form of starch granules with a grain size smaller than 10μ. This volume average diameter is &2
It was μ.

10 parts of this high amylose cornstarch was added as a stilt material to the capsule liquid.

The solid content of the obtained capsule liquid was 51%.

10 parts of a 5% sodium alginate aqueous solution was added to and mixed with the capsule liquid before thickening.

This capsule liquid was roll-coated onto copy paper to a thickness of 115 ffld, and then dried to obtain pressure-sensitive copy paper.

In addition, as a control example, instead of the high amylose cornstarch in Example 1, a particle size of 2 to 3 was added to the stilt material.
Pressure-sensitive copying paper was produced in the same manner as in Example 1 except that 5μ wheat starch was used.

The productivity and performance of pressure-sensitive copying paper according to these Examples and Control Examples are shown in the following table.

As is clear from the above results, the productivity and performance of pressure-sensitive copying paper can be greatly improved by using the durable stilt material of the present invention.

Patent applicant: Hoenen Oil Co., Ltd.

Claims (2)

[Claims] (1) Amicus content of 50% or more and particle size of 3 to 10
A heat-resistant stilt material for pressure-sensitive copying paper made of μ high amylose cornstarch. (2) The heat-resistant stilt material for pressure-sensitive copying paper according to claim 1, which is starch granules obtained by dividing high amylose cornstarch having a particle size of 3 to 10 μm by a classification method.