JPH0258621B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a heat-adhesive sealed form that prevents the occurrence of blocking accidents caused by heat-sensitive adhesives. [Prior art] Conventionally, hot melt adhesive or water-soluble heat sensitive adhesive, etc. is applied to the heat sensitive adhesive part of the form base material in advance.
Heat-adhesive sealed forms that are heat-bonded after printing are widely used, but the use of heat-adhesive sealed forms has increased with the rationalization of office work such as the introduction of computers. Heat-adhesive envelope forms can process multiple types of printed matter at high speed using simple and inexpensive equipment, and are easy to operate, do not require special skilled technicians, and are versatile. It has many excellent features, such as being able to print out a large amount of information, and being able to give the original to the customer at a low cost. [Problems to be Solved by the Invention] However, conventional heat-adhesive sealed forms are coated with a hot-melt adhesive or a water-soluble heat-sensitive adhesive before printing, so they are subject to temperature and humidity fluctuations during transportation, storage, etc. Due to load, etc., blocking accidents often occur before thermal bonding, and solving this problem has been a serious problem for those skilled in the art. In addition, the above-mentioned problem is an urgent problem that needs to be solved in view of the current situation where electronic printers are being introduced as printing methods are required to print kanji characters. Incidentally, electrophotographic methods, electrostatic recording methods, ink mist methods, ink jet methods, and the like are conventionally known as electronic printers, and in the electrophotographic methods and electrostatic recording methods, toner is used for printing. In electrophotography, a photoconductor is charged and exposed to a light image to create an electrostatic latent image, which is developed with toner and then transferred to paper and heat-fixed. There are xerography, electrofax, NP methods, etc. for this method, and there are various printers depending on the type of photoconductive material, formation of the photoreceptor, light image irradiation method, etc., but electronic printers can use plain paper. It is the most commonly used method because it has good printing quality, high speed, and can easily output kanji, figures, form overlays, etc. There are two types of toners: powder toners and liquid toners. Powder toners are colored resin powders with adhesive thermoplastic resin as a binder and pigments, dyes, auxiliary agents, etc. dispersed therein. Toner is usually 1~
With a particle size of 10μ, its softening point is adjusted to 100-150℃. Liquid toner is made by dispersing a toner consisting of a fixing agent, a coloring agent, a charge control agent, etc. in a dielectric liquid with a boiling point of 100 to 200°C, and the fixing agent includes alkyd resin, cyclized rubber, fat Group hydrocarbon soluble natural resins, asphalt, acrylic resins,
Copolymers of higher alkyl esters and vinyl monomers are used. The toner image formed by the above is usually 110 ~
Fixed at 140℃. Therefore, in heat-adhesive envelope forms that use an electronic printer such as Xerography as a printing means, the heat-sensitive adhesive layer on the form base material, which has been applied and printed in advance, is applied during the electronic printer's preheating process or It is expected that it will soften and melt due to heating during the fixing process, causing blocking. Therefore, in order to prevent this blocking, it is possible to use a heat-sensitive adhesive that has a softening point and melting point to prevent it from softening and melting during heating in the preheating process and fixing process. It was expected that more heating would be required than in the preheating step and fixing step, and as a result, the printed toner would melt, resulting in blocking. Below, blocking in a general printing process will be explained in more detail. In the preheating process, the heat-adhesive sealed form advances on a plate-shaped heater while maintaining surface contact. The paper temperature rises to around 120℃. In the fixing process, a heating roll whose surface is treated with silicone or the like is used, and the temperature of the heating roll is usually 160~160°C.
The paper temperature of the heat-adhesive sealed form when it passes through the heating roll is approximately 130°C. The heat-sensitive adhesive on the heat-adhesive envelope form melts and softens, causing blocking mainly in the preheating step, and it is presumed that blocking does not occur much in the fixing step. The reason for this is that, as mentioned above, the preheating process uses a surface contact heating method, so the contact area between the heater and the heat-adhesive sealed form is large and the contact time is long, whereas the fixing process uses a line contact/heating method. Because there is
The contact area is small and the contact time is short. In addition, since the roll surface is treated with a resin having good releasability such as silicone, it is assumed that the degree of blocking occurs in the fixing process is lower than that in the preheating process. Rewetting fixing agents used to solve the problems caused by heat fixing in electronic printers are unsuitable because they cause blocking due to, for example, absorption of moisture in the air. . Furthermore, Japanese Patent Application Laid-Open No. 53-134524 (Method for Manufacturing Heat Sealer Foam) discloses a method of applying an electrostatic powder adhesive after fixing the print. In this method, adhesive is applied to the seal part (thermal adhesive part) after the print is fixed, but if the softening point of the electrostatic powder adhesive is not lower than the softening point of the toner of the electronic printer, the form (form) will not be formed. When heat-sealing (thermal bonding) with electrostatic powder adhesive, there is a risk that the toner of an electronic printer may cause blocking, so electrostatic powder adhesives are limited, and the temperature of heat fixing must be strictly controlled. is necessary. Electrostatic powder adhesive is made by mixing a hot-melt adhesive resin and a charge control agent to form a fine powder, and electrostatic screen printing is performed on the thermally bonded part of the printed form base material.
Since it is applied by electrostatic methods such as charged powder gravure printing, zero printing, and electrophotography, the cost is high and the equipment is large and expensive. The purpose of the present invention is to provide a heat-adhesive sealed form in which a heat-sensitive adhesive is pre-applied before printing and prevents blocking, and also to avoid troubles caused by softening of the heat-sensitive adhesive layer even when used in an electronic printer. It is also an object of the present invention to provide a heat-adhesive envelope form that does not generate heat. [Means for Solving the Problems] The specific structure of the heat-adhesive sealed form of the present invention is such that the print is applied onto a heat-sensitive adhesive layer having a softening point lower than the print fixing temperature, which is provided on the form base material. This is a heat-adhesive type envelope form which is prevented from blocking, characterized in that it is coated with an anti-blocking agent that has a melting point higher than the fixing temperature and is removable with water, alcohol, or a mixture thereof. The present invention will be explained in more detail below. The heat-sensitive adhesive of the present invention includes commonly used hot melt adhesives such as vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polyolefin resin, etc. A hot melt adhesive having a softening point lower than the toner softening point, such as a vinyl acetate resin, is preferred. Anti-blocking agents prevent blocking of the heat-sensitive adhesive layer before printing during transportation, storage, etc., and at the same time, when heat-fixing prints using electronic printers, etc., the heat-sensitive adhesive layer softens and causes problems. It is desirable that the adhesive be easily removed after printing and before thermal bonding, and that it not have any adverse effect on thermal bonding. Such antiblocking agents include partially saponified polyresin vinyl, carboxymethyl cellulose,
It is selected from starch, casein, etc., and partially saponified polyvinyl acetate and carboxymethyl cellulose are preferable, and partially saponified polyvinyl acetate is more preferable for use in electronic printers. The heat-sensitive adhesive is applied to the heat-sensitive adhesive part of the form base material by an appropriate method, but it is preferable to apply it in the form of a suspension or emulsion by roll coating, gravure coating, or roll-type part coating. Applied on one or both sides, depending on the situation. The form base material coated with this heat-sensitive adhesive and dried is then coated with an antiblocking agent. The coating method includes roll coating as described above,
It is applied onto the heat-sensitive adhesive layer by gravure coating or roll-type part coating. The anti-blocking agent is applied in the form of a solution of a liquid such as water or alcohol that dissolves the anti-blocking agent but does not or hardly dissolves the heat-sensitive adhesive layer, or a mixture thereof, especially water and alcohol. It is preferable to dissolve it in a mixture of the following and apply it by a roll method, and by evaporating the solvent and drying it, a heat-adhesive sealed form that is prevented from blocking can be obtained. The blocking-prevented heat-adhesive envelope form of the present invention is printed on a form base material by a conventional method, and then the anti-blocking agent is removed and heat-bonded at a temperature below the softening point of the heat-sensitive adhesive. The above solvent can be used to remove the antiblocking agent,
Preferably, the form substrate is passed between rotating rolls, and the anti-blocking agent is dissolved with a roll impregnated with water, alcohol, or a mixture thereof, and wiped off by the rolls. [Example] Polyvinyl acetate emulsion (manufactured by Nippon Fuller Co., Ltd., #3316) was applied onto a form base material and dried to form a heat-sensitive adhesive layer (thickness: 15 μm). Solutions of polyvinyl alcohol (PVA) and carboxymethylcellulose (CMC) dissolved in various liquids shown in the table below at various concentrations are applied onto this heat-sensitive adhesive and dried to form a coating of anti-blocking agent (thick A diameter of approximately 7μ) was formed. A pressure of 1.0 to 1.5 kg/cm ² was applied to the obtained form base material for 0.7 seconds at the temperature shown in the table to examine the presence or absence of blocking. A form base material to which no anti-blocking agent was applied was tested as a control. The results are shown in the table below.

【table】

[Table] ×…Blocking occurred in a considerable portion.
From the above table, PVA can prevent blocking up to 140℃ if conditions are selected appropriately, and CMC can prevent blocking up to 140℃.
It has been shown that blocking can be prevented up to 100°C. Normally, when an electrophotographic copying machine transfers toner, the paper temperature is around room temperature, and during the preheating process, the paper temperature rises to about 120°C, but it is only at the end of the preheating process that the paper temperature reaches 120°C, which is the maximum. Even if blocking can be prevented at 120℃, the blocking prevention effect will be sufficient.Also, taking into consideration the passing time of the preheating process and the time until the heat-sensitive adhesive layer softens, the temperature at 100 to 110℃ is sufficient.
If blocking is prevented (under the experimental conditions shown in the previous table), blocking can be effectively prevented. [Effects of the Invention] The blocking-prevented heat-adhesive envelope form of the present invention has an anti-blocking agent layer formed on the heat-sensitive adhesive layer, so blocking does not occur during storage, transportation, etc. before printing. It is also possible to prevent the occurrence of blocking during heat fixing of prints by electronic printers, thereby easing the temperature control of heat fixing. Moreover, since the anti-blocking agent is easily removed by a simple device before thermal bonding, it does not have a negative effect on subsequent thermal bonding. The above operation is easy, and printing and thermal bonding can be done by attaching a simple and inexpensive device to the conventional device, so the present invention solves the problem of blocking, which was considered an unavoidable drawback in the past. This is an excellent heat-adhesive sealed form that overcomes this problem.

Claims (1)

[Scope of Claims] 1. On a heat-sensitive adhesive layer provided on a form base material and having a softening point lower than the print fixing temperature, the adhesive has a melting point higher than the print fixing temperature and contains water, alcohol, or a mixture thereof. 1. A heat-adhesive sealed form that prevents blocking, characterized in that it is coated with an anti-blocking agent that is removable. 2 The heat-sensitive adhesive is polyvinyl acetate or vinyl chloride.
2. The heat-adhesive sealed form that prevents blocking according to claim 1, which is a vinyl acetate copolymer or a polyolefin, and the antiblocking agent is partially saponified polyvinyl acetate, carbomethoxycellulose, starch, or casein.