JPH082683B2 - Thermal ink roll - Google Patents

Description

[Detailed Description of the Invention] Industrial field of the invention This invention is for printing tickets, food tickets,
The present invention relates to a heat-sensitive ink roll capable of drawing characters and symbols on labels, stickers, packaging materials, etc.

2. Description of the Related Art Ink rolls and transfer foils are used to print characters and symbols on ticket vending machines such as tickets and food tickets, and on labels, stickers and packaging materials.

However, when printing with an ink roll, if the ink roll is new, the ink will come out well and the ink will be on your hand just by touching the printing surface, and you will not feel uncomfortable with a ticket vending machine. In addition, when used for labels, stickers, packaging materials, etc., the printed surface may not be readable unless the printed surfaces overlap and rub against each other until it is dried (= ink is absorbed by the substrate such as paper). there were.

On the other hand, if the transfer foil is used, it does not get dirty even immediately after printing or even if the printed surface is touched, but if the cost is increased or the transfer foil is cut off, it is not printed at all and maintenance is troublesome.

Therefore, a method of using a thermal ink roll has become popular as an alternative to the above ink roll or transfer foil. When characters and the like are printed using a heat-sensitive ink roll, for example, the method shown in FIG. 1 is often used. In FIG. 1, the ink roll 1 is heated by the heater 2, and the character 3 held by the character holder 4 is alternately pressed by the ink roll 1 and the base 7 every 180 ° rotation, and the base 7 Characters are printed on. Reference numeral 5 is a heater and 6 is a platen roll.

Problems to be Solved by the Invention However, there is nothing that sufficiently satisfies the adhesiveness and heat resistance of a heat-meltable ink to a substrate such as paper or film.

The heat-fusible inks used in conventional heat-sensitive ink rolls are base polymers consisting of ethylene-vinyl acetate copolymer, polyamide resin, nylon resin, polyester resin, polypropylene resin, rosin derivative, terpene resin, and petroleum. Resin, coumarone-indene resin,
Tackifier resin made of styrene resin, isoprene resin, wax such as paraffin wax, microcrystalline wax, synthetic wax, modified wax, polypropylene wax, carbon black, cyanine blue, titanium oxide, lake red, nigrosine. A colorant such as oil black was heated and melted and then heated and dispersed by a disperser such as a roll mill or an attritor.

Such a heat-meltable ink has a melting start temperature (T ₁ ° C)
And melting end temperature (T ₂ ℃) is large (ΔT ℃) and lacks heat resistance. In particular, melting starts at 40 to 50 ℃ and ink strength becomes weak, so rub the printed characters and symbols with your fingertips. And 2
The print may disappear after three times, or the printed characters may become unclear by being rubbed by the guide roll of a ticket vending machine or the guide roll of a packaging line that incorporates a printing machine that prints the date of manufacture. .

Therefore, a heat-sensitive ink roll having excellent adhesiveness to a printed substrate and heat resistance has been desired.

MEANS FOR SOLVING THE PROBLEM The present invention has a melting point of 80 to 120 ° C. in a continuous foam.
And the difference between the melting end temperature and the melting start temperature is 30 ° C or less,
In addition, by impregnating a hot-melt ink having a melt viscosity of 500 to 10,000 cps at 150 ° C, the adhesiveness to a substrate such as paper or film and heat resistance are improved, and the above problems are solved. is there.

Here, the difference between the melting end temperature and the melting start temperature (ΔT
Is a differential scanning calorimeter (DSC-3) manufactured by Shimadzu Corporation.
Type 0) is used as the melting start temperature (T ₁ ° C) at which the temperature starts to shift from the baseline position to the endothermic side, and the temperature that returns to the baseline position is taken as the melting end temperature (T ₂ ° C). Calculated by ℃ = T ₂ ℃ -T ₁ ℃.

If there are many endothermic peaks, the melting energy
The peak obtained by removing the peak of 30% or less is used as the melting end temperature or the melting start temperature.

 The melt viscosity is measured with a B type viscometer.

To embody the invention of the present application, as the heat-meltable ink, a heat-meltable ink mainly composed of a base polymer and a colorant is used, which is produced by heating and melting the components. Next, it is heated and dispersed by a disperser such as a roll mill and an attritor,
A heat-sensitive ink roll is produced by impregnating a continuous foam with heat.

As the base polymer, polyethylene copolymer resin,
The melting end temperature of crystalline polyester resin is 80-120 ℃
And the difference between the melting end temperature and the melting start temperature is 30 ° C or less,
Moreover, the melt viscosity at 150 ° C is 500-1000 with a B type viscometer.
Anything within the range of 0 cps can be used.

As the colorant, a pigment or dye that does not decompose or deteriorate at a temperature of 120 to 160 ° C can be used. By adding this substance in the base polymer in a solid content ratio of 3 to 20 wt%, the melt viscosity of this heat-meltable ink is measured by a B-type viscometer at 150 ° C. to 500 to 1000%.
Make it 0 cps.

When the melting end temperature (T ₂ ° C) is 80 ° C or less, printed characters and symbols are easily erased by rubbing with your fingertips, and are easily blurred by rubbing with a guide roller in the machine.

When the melting end temperature (T ₂ ° C) is 120 ° C or higher, impregnation into the continuous foam becomes difficult.

The difference between the melting end temperature and the melting start temperature (ΔT ° C) is 30 ° C
When the above temperature is reached, even if the melting end temperature (T ₂ ℃) is in the range of 80 to 120 ℃, the melting start temperature (T ₁ ℃) will be low, resulting in poor adhesion and rubbing stains when passing through the guide roller. .

Further, if the melt viscosity is 500 cps or less at 150 ° C, the heat-meltable ink comes out quickly from the continuous foam, the durability is poor, and the excess heat-meltable ink causes stains and unclear printing. . On the contrary, at a melt viscosity of 150 ° C, 1
If it exceeds 0000 cps, it will be difficult to impregnate the continuous foam with the hot-melt ink, and the durability will be poor and the printing clarity will be poor.

Example 1 Melting end temperature by randomly copolymerizing various ratios of terephthalic acid, sebacic acid and dihydric alcohol
Difference ΔT = T ₂ -T ₁ and T ₂ and the onset of melting temperature T ₁ of at the 20-25 ° C.,
A crystalline polyester resin having a melting end temperature T ₂ of 60 to 130 ° C. was obtained. Using this crystalline polyester resin, carbon black 5 parts (Printex 25, made by Degussa) 95 parts of crystalline polyester resin were mixed and heated to melt, and heated and dispersed at 120 ° C using a three-roll mill. , Dispersed hot-melt ink with continuous foam urethane sponge (Bridgestone Co., PF-
20) was heat-impregnated with 25 g to obtain eight kinds of heat-sensitive ink rolls having different T ₂ as follows. This was attached to a hot printer HR-40 manufactured by EDM, and printed on polyester packaging material, cellophane laminate packaging material, OPP packaging material and CPP packaging material. The results are shown below.

As a result of the evaluation, the thermal ink roll having a T ₂ temperature of 80 ° C. to 120 ° C. gave good results.

Example 2 Copolymerizing a dibasic acid and a dihydric alcohol and changing the molecular weight thereof, a crystalline polyester having V _S150 = 300 cps (Almatex TTR-3) and a crystalline polyester having V _S150 = 10000 cps (Almatex TTR-1) Got By mixing and using these two types of crystalline polyesters, 9 types of thermal ink rolls having different melt viscosities were obtained at a weight ratio of 90:10 with carbon black (Printex 25).

As a result of the evaluation, the thermal ink roll impregnated with the hot-melt ink having V _S150 of 500 cps to 10,000 cps gave good results.

Example 3 Six types of thermal ink rolls having ΔT of 11 ° C. to 40 ° C. were obtained by changing the ratios of the crystalline polyester resin, paraffin wax and carbon black. The evaluation results are shown below.

As described below, a heat-sensitive ink roll having a ΔT of 30 ° C. or more did not have sufficient heat resistance, a product having practicality was obtained at 30 ° C. or less, and a very good product was obtained at 20 to 27 ° C. .

EFFECTS OF THE INVENTION By using the heat-sensitive ink roll of the present invention, regardless of the characteristics of the base material such as paper or film, heat resistance can be obtained, and clear printing that is strong against rubbing stains can be performed. Adhesion and heat resistance, which are drawbacks, were improved. At the same time, it is possible to print regardless of the characteristics of the base material, so it can be used for printing the manufacturing place, product name, etc., the base material such as paper and film can be unified, and various kinds of paper and film etc. can be stored. The effect of eliminating the need was obtained.

[Brief description of drawings]

FIG. 1 shows an example of a method for printing characters and the like using a thermal ink roll. 1 ... Ink roll, 2 ... Heater, 3 ... Type, 7 ... Base material.

Claims (3)

[Claims] 1. A heat-melting property, wherein the melting end temperature is 80 to 120 ° C., the difference between the melting end temperature and the melting start temperature is 30 ° C. or less, and the melt viscosity is 500 to 10,000 cps at 150 ° C. A heat-sensitive ink roll characterized in that continuous foam is impregnated with ink. 2. The heat-meltable ink comprises a base polymer and a coloring material, and the base polymer has a melting end temperature of 80 to 120 ° C. and a difference between the melting end temperature and the melting start temperature is 3 °.
If the melt viscosity is below 0 ℃ and the melt viscosity is 150 ℃, it is 500 to 10,000
The thermal ink roll according to claim 1, which is cps. 3. The heat-sensitive ink roll according to claim 2, wherein the base polymer is a crystalline polyester resin.