JPS623192B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive, and more particularly to a hot-melt powder adhesive for electrostatic gravure printing that allows good printing by electrostatic gravure printing.

Conventional adhesives include (1) chemical reaction type, (2) solvent evaporation or diffusion type, (3) hot melt type, (4) delayed adhesive type,
(5) film type, (6) pressure sensitive type, etc. Among these, hot melt type adhesives are generally ethylene-based adhesives.
Examples include vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ionomer, phenoxy, polyamide, polyester, polyethylene, polyvinyl acetate, and polyvinyl butyral.

On the other hand, powder adhesives include polyethylene, polyvinyl chloride, polyvinyl acetate, copolymers thereof, acrylic resin, etc., and are used for adhering interlining in sewing and joining webs in the production of nonwoven fabrics. It's being used. One method of dispersing adhesive powder is to supply the powdered adhesive from a hopper to a grooved drum rotating at high speed, and then use the centrifugal force of the rotation of the drum to spread it onto the web through a gap provided at the bottom. Alternatively, a grooved drum at the bottom of the hopper rotates and a bristled brush cylinder brushes the powdered adhesive from the grooves onto the web.

Further, as a method for applying the powder adhesive, a method using electrostatic gravure printing may also be considered.
The electrostatic gravure printing method used here uses powder ink instead of the liquid ink used in conventional gravure printing, and this powder ink is electrostatically transferred to the printing material to create the desired image. More specifically, powder ink is placed on a gravure printing plate (conventional gravure plate or mesh gravure plate), filled into the cells with a doctor, ink in non-image areas is removed, and then corona discharge After charging the ink with
In this method, the ink in the cell is electrically attracted and adhered to the printing material by contacting an electrode with an opposite charge to the ink from the back side or by applying a corona discharge.

Therefore, if a powder adhesive obtained from the adhesive described above is used instead of powder ink in electrostatic gravure printing, printing (application) of the powder adhesive can be performed using the electrostatic gravure printing method.

However, simply using powdered adhesive obtained from adhesives instead of powdered ink in electrostatic gravure printing does not provide the fluidity required for the ink, and the ink tends to stick to the doctor blade, etc. A problem arises. In view of the above points, the present inventors conducted intensive research and completed a polyamide-based hot-melt powder adhesive for electrostatic gravure printing that can be printed (coated) favorably by an electrostatic gravure printing method. That is, the present invention
Electrostatic gravure characterized by being mainly made of polyamide resin produced by the reaction of dimer acid, which is a dimer of linoleic acid, and polyamine, and to which finely powdered silicon dioxide and finely powdered solid lubricant are added. This is a powder adhesive for printing.

The present invention will be explained in detail below.

In general, the general characteristics required for powder ink used in electrostatic gravure printing are chargeability,
There are four points: particle size distribution, fluidity, and fixability, but fluidity and resistance to sticking to the doctor blade are particularly important for powder adhesives for electrogravure printing. When filling gravure plate cells at high speed, fluidity must be good. Also, if the fluidity is poor, it tends to stick to the doctor. Flowable particles are determined by particle shape, particle size, and surface properties. Further, powder ink for electrostatic gravure printing needs to have appropriate charging properties, and powders that are strongly triboelectrically charged are not suitable for filling cells.

The present inventors investigated various adhesives and auxiliary agents that can constitute a powder adhesive for electrostatic gravure printing that can perform good printing (coating) using the electrostatic gravure printing method, and found that dimerization was found. Among the various polyamides produced by reacting fatty acids with diamines and polyamines, as shown in the reaction formula below, the combination of dimer acid, which is a dimer of linoleic acid, and polyamines, mainly diamines. We have found that a powder adhesive that is mainly composed of polyamide produced by a condensation reaction and to which finely powdered silicon dioxide and finely powdered solid lubricant are added is particularly excellent.

The polyamine that can be used in the present invention is mainly diamine, and various aliphatic diamines, alicyclic diamines, aromatic diamines, etc. can be used. Specifically, ethylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, etc. , hexamethylene diamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1.
9-diaminononane, 1,10-diaminodecane,
Examples include 0-phenylenediamine, m-phenylenediamine, and P-phenylenediamine.

Incidentally, the structural formula of dimer acid is as follows.

The polyamide resin produced by the reaction of a dimer acid, which is a dimer of linoleic acid, and a polyamine according to the present invention has a narrow softening point range, and is almost unaffected by temperature up to a temperature very close to the softening point. Conversely, when the temperature is slightly lower than a certain point, it solidifies rapidly. Also,
Water resistance and moisture resistance are good, and frictional electrification is not too strong. It also has excellent flexibility, including cellulose derivatives, paper, glassine, cloth, metal, glass, cork, etc.
It exhibits excellent adhesion to certain rubber, polyethylene, polyester, and other plastic surfaces. Furthermore, it has excellent properties such as good storage stability, stability during long-term storage, and no blocking even under fairly severe conditions.

However, polyamide having the above composition alone lacks fluidity and also tends to stick to the doctor blade. Therefore, in the present invention, in order to deal with such a phenomenon, finely powdered silicon dioxide is mainly used to impart appropriate fluidity, and finely powdered solid is mainly used to prevent sticking to the doctor blade. Add lubricant. Nitrogen boron and talc are particularly excellent as fine powder solid lubricants. If the powder adhesive for electrogravure printing has such a composition, the temperature required for adhesion can be lowered, and it is also possible to provide the fluidity necessary for electrogravure printing and prevent it from sticking to the doctor blade. Therefore, printing (coating) using a powder adhesive for electrogravure printing can be carried out satisfactorily.

One of the applications of the electrogravure printing powder adhesive of the present invention is a heat sealer form.

Recently, the heat sealer form system has become popular as a method of mailing output forms, but since the conventional heat sealer form is coated with hot melt adhesive before printing, it is difficult to transport or store the form before sealing. When printing with an electronic printer that uses toner, which is prone to problems with blocking due to temperature, humidity, and load, and which is expected to become more popular in the future, the print is fixed using a heating method. The hot melt adhesive softens during fixing, which has the drawback of easily causing trouble. However, the above drawbacks can be overcome by applying the adhesive of the present invention to the heat-sealed portion after printing, instead of using the conventional method of applying a hot melt adhesive before printing.

In addition, when applying the powder adhesive for electrostatic gravure printing of the present invention to a form printed by an electronic printer using toner, the softening point of the powder adhesive for electrostatic gravure printing of the present invention is lower than the softening point of the toner. If the softening point is high, the portion printed with toner will cause blocking during sealing, so it is necessary to set the softening point of the powder adhesive lower than that of the toner.

Examples are shown below.

Example 1 Polyamide resin DPX-985 (manufactured by Japan General Mills Chemical Co., Ltd., softening point 86.5°C) was pulverized using a pulverizer PJM-
100NP jet mill (manufactured by Nippon Neumatic Co., Ltd.)
(particle size: 5 μm to 30 μm). Next, a mixture having the following composition was prepared.

DPX-985 powder 97.5 parts by weight Silicon dioxide (AEROGIL#972, manufactured by Nippon Aerosil Co., Ltd.) 1. Boron nitride (manufactured by Denki Kagaku Co., Ltd.) 1.5. Place it in the concave part of the gravure plate at the point (depth 100μ), and use a doctor to remove the powder adhesive for electrostatic gravure printing in the non-image area. Next, after applying a positive corona discharge (+6KV) to the powder adhesive for electrostatic gravure printing filled in the concave part of the plate, the form base printed using toner with a kanji printer manufactured by Nippon Univac Co., Ltd. The powder adhesive for electrostatic gravure printing was electrostatically transferred to the firm base by superimposing it on top and applying a negative corona discharge (-6KV) from the back side. Next, fold the obtained heat sealer form in half and use the preheater (length 185 mm).
A two-layered envelope was sealed by passing the envelope between a hot plate (heat plate, temperature: 150°C) and two pairs of roll heaters (temperature: 130°C) at a speed of 24 m/min. When I opened this envelope from the perforation, I found that the characters printed with toner by the kanji printer were not blocked on the paper on the other side.

Example 2 Polyamide resin Versamide 950 (manufactured by Japan General Mills Chemical Co., Ltd., softening point 90-100°C) was pulverized using a pulverizer.
It was pulverized (particle size: 10 μm to 40 μm) using a PJM-100NP diet mill (manufactured by Nihon Neumatic Co., Ltd.). Next, a mixture having the following composition was prepared.

Versamide 950 fine powder 97.5 parts by weight Silicon dioxide (AEROGIL #200, manufactured by Nippon Aerosil Co., Ltd.) 1. Boron nitride (manufactured by Denki Kagaku Co., Ltd.) 1.5 The above mixture was used as a powder adhesive for electrostatic gravure printing.

Example 3 Polyamide resin DPX-985 (manufactured by Japan General Mills Chemical Co., Ltd., softening point 86.5°C) was pulverized using a pulverizer PJM-
100NP jet mill (manufactured by Nippon Neumatic Co., Ltd.)
After pulverizing (particle size 10μ to 40μ), a small amount of surfactant (Lipon F manufactured by Lion Oil Co., Ltd.) was added.
The mixture was placed in a hot water vat at 60°C, stirred, then cooled, taken out, and dried to obtain a fine powder.

Next, a mixture having the following composition was prepared.

DPX-985 powder 93 parts by weight Silicon dioxide (AEROGIL #972, manufactured by Nippon Aerosil Co., Ltd.) 5. Talc (manufactured by Kanto Kagaku Co., Ltd.) 2. The above mixture was used as a powder adhesive for electrostatic gravure printing.

Example 4 99 parts by weight of polyamide resin DPX-985 (manufactured by Japan General Mills Chemical Co., Ltd., softening point 86.5°C) and Diamond Navy Blue ER-FS (manufactured by Mitsubishi Kasei Corporation)
After blending 1 part by weight on two heated rolls, coarsely pulverizing the mixture, and then using a jet mill (manufactured by Nippon Neumatic Co., Ltd.)
PJM-100NP) to obtain a powder of 10μ to 40μ.

Next, a mixture having the following composition was prepared.

DPX-985 colored powder 97.5 parts by weight Silicon dioxide (AEROGIL #972, manufactured by Nippon Aerosil Co., Ltd.) 1. Boron nitride 1.5 parts by weight If the above mixture is used as a powder adhesive for electrostatic gravure printing, it will be used when performing electrostatic powder gravure printing. In addition, the area to which the adhesive was applied (printed area) became clear and workability was improved.

Claims (1)

[Claims] 1 An electrostatic product that is mainly composed of a polyamide resin produced by the reaction of dimer acid, which is a dimer of linoleic acid, and diamine, and to which finely powdered silicon dioxide and finely powdered solid lubricant are added. Powder adhesive for gravure printing.