JPH0312267A - Pattern coating method of hot melt type adhesive - Google Patents

Abstract

PURPOSE:To uniformize the thickness of a coating film by making a coating pattern precise by applying a hot melt type adhesive to the surface of a base material by a roll to which a mesh like intaglio pattern is applied by transfer coating and heating the coated material to level the adhesive layer and subsequently pressing said adhesive layer to flatten the same. CONSTITUTION:An adhesive HM is heated and melted by a hot melt applicator 9 to be supplied to a pan 3 and transferred to the surface of a fed object O to be coated in a mesh like state by the action of an intaglio roll 1 to which a mesh like pattern is applied and a scraper 2 to be applied thereto. Continuously, the coated object O is heated to predetermined temp. by a heater 5 to lower the viscosity of the adhesive and the granular adhesive is leveled to convert the granular HM1 to the tray-like HM2. Further, the adhesive layer is pressed by pressure rolls 7, 8 to become flat. By this method, a pattern coating article of a hot melt type adhesive having a precise pattern contour and high uniformity in a required thickness is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to pattern coach-in of hot-melt adhesives [Prior Art] At present, the types and quantities of adhesive paper products are enormous. Adhesive paper products include adhesive tapes, labels affixed to release paper, office label paper, delivery slips, adhesive paper for fixing wall materials, medical bandages, and many other products.

Originally, adhesives were solution-type (water-soluble or solvent-type).
There are two types: hot melt type and hot melt type.The former is applied by dissolving the adhesive in water or a solvent to lower the viscosity, and the latter is applied by heating to lower the viscosity. What are the advantages and disadvantages of these?

The solution type can freely adjust the viscosity to make it easier to apply, but after application, the water or solvent is blown off, resulting in a large waste of material and being uneconomical. In addition, the hot melt type has drawbacks such as restrictions on heating temperature, making it difficult to freely adjust the viscosity, and making coating work difficult. However, its adhesive strength is much greater than that of the solution type, and its material costs are also relatively low.

Conventionally, both of these coating operations have been carried out using a roll method to uniformly coat the entire surface of a long piece of paper.

However, recently, demand for pattern application (coating) has increased.

What is pattern coating?1 For example, Fig. 10A, Fig. 10
Figure B.

As shown in FIG. 10C, this is a method of continuously applying a certain pattern. The chevron-shaped pattern in FIG. 10B shows an example of use in applying adhesive to envelopes.

In order to pattern coat the adhesive, the inventor conducted the following experiment.

(1) Letterpress roll coating A, case of using a solution-type adhesive A vinyl acetate emulsion adhesive was used as the solution-type adhesive in an experiment. Please refer to FIG.

In the case of a solution type, the hot melt applicator (19) shown by the phantom line in the figure is of course unnecessary.

The dipping roll (11), the letterpress roll (12), and the impression roll (I4) were used in the same way as before, and after coating the base material (Oa) with a solution-type adhesive, a release paper was attached to the base material (Oa) using a pressure roll (16). The letterpress pattern is rectangular (182,4■×
Here are the results of an experiment with 56 intestines) (see Figures 6 and 7).

1) The outline of the coating pattern is disordered.

2) The coating film thickness is non-uniform.

3) Especially the periphery of the pattern becomes thick.

4) The coating film becomes thinner in proportion to the increase in coating speed.

5) The coating film thickness is unstable over time.

6) Dipping roll (11) and letterpress roll (12)
The adjustment between 11A and 11A is very delicate, and it is difficult to set a stable coating film thickness.

7) It is difficult to uniformly obtain the minimum necessary thickness (10 microns or more) for an adhesive film.

8) After the base material (paper) was attached to the female pattern, many shadings occurred in the print on the base material (because the coating film thickness was uneven).

As mentioned above, it has been found that it is not possible to obtain a pattern with a precise outline, and it is extremely difficult to obtain the minimum thickness and uniformity required for an adhesive film.

B. When using a hot-melt adhesive When using a hot-melt adhesive, first apply the hot-melt adhesive in the hot-melt applicator (19) as shown by the imaginary line in Figure 5. It is heated and melted, then supplied into a small heat insulating tank (13A), and transfer coating is performed.The subsequent steps are the same as in the conventional method as shown in the figure. The experimental results are similar to those for the solution type described above, but their degree is slightly better. Rather, it was easy to maintain the minimum thickness of the coating film. However, there was considerable non-uniformity in the thickness. (2) Intaglio roll coating A, when using a solution-based adhesive This intaglio roll transfer coating device is almost the same as the conventional one, and the intaglio pattern is a rectangle (18
2.4 am x 56 m) (see Figures 8 and 9).

1) The outline of the coating pattern is disturbed (however, the main term (1) -
Slightly better than A-1)).

2) The coating film thickness is non-uniform (however, main term (1)-A
-2) slightly better).

3) The coating film becomes thinner in proportion to the increase in coating speed (however, it is slightly better than main item (1)-A-4) 4) After pasting the base material (paper) on the release paper, Many shadings (unevenness) occurred in printing on the base material (same as main item (1)-A-8).

As mentioned above, it appears to be slightly better than the main solution type, but it is still not sufficient.

B. In the case of using a hot-melt adhesive, the experimental results tended to be better overall than in the case of using the above-mentioned solution-type adhesive, and in particular, although the thickness of the coating film was uniform, It was possible to maintain a minimum thickness (10 μm) or more necessary for an adhesive film.

Results of the above-mentioned scaled experiment 9 The present inventor studied improvement measures based on the experiment (2)-B above.

(Issue to be solved) In addition to the experimental problems mentioned above, in the case of solution-type adhesives.

The production line becomes expensive because a drying process is required.

Environmental pollution due to the use of organic solvents, difficulty in controlling the degree of dilution of the concentration used, the need for humidity control work to correct curling of the coated material, especially in the case of water-soluble solvents, and adhesives whose viscosity changes depending on the season. There were drawbacks such as difficulty in controlling the temperature at which the agent was used. However, in the case of hot melt adhesives, these drawbacks can be eliminated.

Therefore, the motive of the present invention was to carry out intaglio roll transfer coating using a hot-melt adhesive to make the coating pattern more precise and the coating film thickness more uniform.

[Means to solve the problem]

The gist of the present invention is to apply a hot-melt pressure-sensitive adhesive onto a substrate surface using a roll provided with a mesh-like intaglio pattern, and then to heat and level the mesh-like coated material.

Immediately after that, pressure is applied using a roller or the like to flatten the surface.

The method will be explained with reference to the drawings. Please refer to FIG.

Adhesive (HM) with hot melt applicator (9)
is heated and melted to an appropriate temperature and supplied into a pan (3), and by the action of an intaglio roll (1) with a mesh pattern and a scraper (2) that are immersed in the pan and rotated, The above adhesive (HM) is applied to the object to be coated (O)
Transfer coated onto the surface in a mesh pattern. As shown in Fig. 2A and Fig. 2B (II D I+ arrow view), the applied state is that the melted adhesive forms a network, that is, a large number of small particles (HMx), and is spread under a certain pattern. It is attached to. Subsequently, they are heated to the required temperature by means of a heater (5, a hot air device is shown in FIG. 1) and the viscosity is reduced. Then, the granular adhesive is leveled as shown in FIGS. 3A and 3B (11E 11 arrow view), that is, the granular shape (HM 1 ) becomes dish-shaped (HMi).

Furthermore, these are pressed by pressure rolls (7, 8) into a flat shape. FIGS. 4A and 4B (view from arrow "F") show a state in which pressure is applied through the M pattern paper (R) to flatten it.

According to this method, there is no disturbance in the outline of the pattern as in the conventional letterpress or intaglio transfer shown previously (Fig. 6, Fig. 7, Fig. 8, Fig. 9, etc.), and the pattern No unevenness is observed inside, and a hot-melt adhesive pattern coating with precise pattern contours and high uniformity in the required thickness (10 to 30 microns) can be obtained.

In addition, experimental data obtained using an experimental apparatus based on the method of the present invention will be listed below.

(1) Intaglio roll diameter x @ 58.7mφ x 56■ width intaglio
Mesh etching intaglio intaglio pattern size 182.4 m length x 56 am width (pattern interval 2 m) Intaglio mesh dot size 0.5 ■ φ Long item) Thickness 80μ (80g/proof) (3
) Release paper (long) thickness 80μ (80g/I) (4
) Adhesive used Nippon Fuller Model number JHL-10
3-85G Melt viscosity 22,000cps/ 160℃ Softening point
109℃ (5) Capacity and temperature of adhesive in pan 70cc-1
85℃ (6) Feeding speed of base paper and release paper 50m/win (
7) Hot near blower air volume, speed and temperature 500Q/
win-9,3m/5ac-200℃ (8) Temperature of pressure roller and pressure 80℃-10kg/j (9) Size of adhesive particles immediately after transfer 0.4-φXSOμ high The above experimental results are It is as follows.

a. Coating film thickness Roll center part 22μ Right side of roll (with respect to the flow direction) 23μ Roll Left side (with respect to the flow direction) 23μb, Smoothness Good with no visible irregularities.

In the above experiment, it should be noted that the amount of molten hot-melt adhesive in the pan (3) should be kept as small as possible. Although it depends on the application speed, it is important to limit the amount of application to about 1 minute, or at most 3 minutes. The reason is to prevent changes in the physical properties of the adhesive.

〔effect〕

According to the method of the present invention, a hot melt adhesive can be coated even more uniformly with a certain required pattern and thickness (10μ to 30μ).

[Brief explanation of the drawing]

Figure 1 is a detailed explanation of the present invention. Figure 2A is the same as above.
Figure 2B is an enlarged view of section A″, above II p Figure 4B is an enlarged view of section ``'C'' in Figure 1. Figure 4B is the upper II F of the same figure.
I+ arrow view Figure 5 is an explanatory diagram of the conventional letterpress type roll coating method and structure. Figure 6 is a diagram showing the adhesive attached to the letterpress portion of the conventional letterpress roller. Figure 8 is a diagram of the adhesive being embedded in the intaglio part of a conventional intaglio roller. Figure 9 is a diagram of the state of transfer coating from the above-mentioned intaglio roller to the target. 1OA, IOB, IOC diagrams are examples of patterns in pattern coating Explanation of main symbols

Claims (2)

[Claims] (1) A heated and melted hot melt adhesive (HM) is transferred onto the supplied substrate (O) surface while scraping with a roll (1) provided with a mesh intaglio,
Next, the granular materials (HM_1) transferred in a mesh pattern are further heated and melted to level them (HM_2), and then the leveled materials are pressed with pressure rolls (7, 8) to make them more flat ( HM_3) A pattern coating method for a hot melt adhesive, which is characterized by forming a hot melt adhesive. (2) When pressurizing with the pressure rolls (7, 8), a release paper (R) is inserted between the pressure rolls (7, 8) and the pressure is applied to flatten the surface and the release paper is attached. 2. A method for pattern coating a hot melt adhesive according to item 1.