JPH0615055B2 - Adhesive coating method and device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive application method and apparatus for preventing skin-based adhesiveness and deterioration of a water-based adhesive in a roll coater which is used for an adhesive work. Is.

(B) Conventional technology A roll coater is widely used when applying a water-based adhesive to an adherend. However, while the roll coater is in operation, water in the water-based adhesive gradually evaporates, resulting in water-based adhesive. An increase in the evaporation residue of the agent occurs.

Along with the increase of the evaporation residue, the viscosity of the water-based adhesive also gradually increases, and in some cases, the adhesive becomes gel in the roll coater and cannot be applied to the adherend.

Further, as the viscosity of the water-based adhesive increases, skinning occurs in a roll, but the skin of the water-based adhesive generated on the roll does not dissolve even when dispersed again in the water-based adhesive, and becomes coarse particles. A lot of unevenness will occur on the coated surface.

In particular, when bonding thin paper, these irregularities appear on the surface of the product as they are, and thus the commercial value is significantly impaired.

Therefore, when using a roll coater, how to suppress the deterioration of the adhesive on the roll is an important point.

The increase in viscosity and skinning due to water evaporation of this water-based adhesive increase as the temperature rises and the humidity decreases. It is relatively small and increases as the evaporation residue of the water-based adhesive increases.

Furthermore, when the alteration of the adhesive on the roll was examined, the following was found.

First, the substrate to which the adhesive is applied is usually of various sizes, and when purchasing a roll coater, the effective width of the roll is determined by the widest substrate used. Therefore, in normal operation, a part of the effective width of the roll is used, and the portion on the roll surface where the base material does not pass is particularly easily skinned.

Second, the water-based adhesive is constantly consumed during the bonding operation and new adhesive is added, but usually the newly added water-based adhesive is added to a portion on the roll by a piped nozzle or dipper. Therefore, it takes time for the aqueous adhesive remaining in the roll coater and the newly added aqueous adhesive to be uniformly mixed, rather than being applied uniformly over the entire effective width of the roll. Therefore, as the distance from the position where the water-based adhesive is supplied increases, it becomes easier to skin.

Therefore, conventionally, in the bonding work, a water-based adhesive having a relatively low evaporation residue is used, and pressing is performed for a long time.
In such an operation, the viscosity increase of the water-based adhesive itself on the roll is relatively small, the water-based adhesive is constantly consumed by the bonding operation, and a new water-based adhesive is added, so that it remains in the roll coater. The water-based adhesive and the newly added water-based adhesive were well mixed and kept in good condition.

However, in recent years, water-based adhesives having a high evaporation residue have been used for the purpose of improving workability due to demands such as reduction of pressing time after application of the adhesive. A water-based adhesive having a high residue causes a significant increase in viscosity in a relatively short period of time, making it impossible to apply it uniformly, and causing a large number of coarse particles as described above due to skinning.

Therefore, in order to prevent such deterioration of the water-based adhesive,
So-called "water casting" has been performed in which water is added to the water-based adhesive in the roll coater in advance. However, the amount of water evaporated from the water-based adhesive varies greatly depending on the weather, temperature, and humidity of the day. The fact is that the amount of water added to the water-based adhesive is determined by experience.

Therefore, when the amount of water to be added is small, it is not possible to prevent the deterioration of the water-based adhesive. On the contrary, when the amount of water is too large, the viscosity of the water-based adhesive is extremely decreased and the adhesion speed is decreased, resulting in poor adhesion. .

Attempts have also been made to prevent the evaporation of water from the water-based adhesive by blowing high-heat steam, but the equipment becomes large-scale and the temperature around the roll rises because the steam itself has a high temperature. It ’s also very dangerous because
Moreover, when the steam was blown out from the tip of the nozzle, it became a strong wind, and a good result was not obtained.

As described above, since the deterioration of the water-based adhesive in the roll coater has a great influence on the bonding work, it is necessary to prevent the deterioration of the water-based adhesive, and in this case, a simple and safe method is required. .

(C) Disclosure of the Invention As a result of studying a method for preventing deterioration of the water-based adhesive due to water evaporation, the present inventor covered the roll portion of the roll coater and humidified it toward the roll portion. It has been found that extremely excellent stability can be obtained by arranging the outlet of the container and humidifying at room temperature by the humidifier.

The following four are considered to be features of preventing the deterioration of the water-based adhesive due to water evaporation.

That is, firstly, in order to prevent the roll coater from being skinned on the roll, it is most effective to directly humidify the adhesive portion under the most severe conditions of the roll portion. By arranging one or more outlets of the humidifier provided on the outside toward the roll part, it is possible to effectively suppress skinning on the roll.

Secondly, the roll portion is covered, but this cover does not try to seal the roll portion to a high humidity state, and the portion through which the substrate passes is left open. The purpose of the cover is to prevent the influence of external wind, etc., so that the mist-like water passage from the humidifier can be stably sent to the roll part, and it is also effective to slightly blow air from the humidifier. It is for sending mist-like water droplets to.

Thirdly, since the humidifier is used at room temperature, the temperature in the cover can be kept low, and the evaporation of water can be effectively suppressed.

Fourth, the humidifier is so compact that it can be installed easily, is easy to handle, and is highly safe.

FIG. 2 shows (a) to (d) in a range 11 through which the water-based adhesive supply port 12 and the base material (adhered material) of the coating roll pass.
And the range S in which skinning is likely to occur,
The farther it is from the adhesive supply port 12, the easier it is to skin,
The degree becomes worse.

For example, when the water-based adhesive is supplied from the center of the roll, it becomes easier to skin the both ends of the roll (Fig. 2 (a)), and the water-based adhesive is supplied from the right end toward the roll. When it is attached, it is easier to skin the closer it is to the left end (Fig. 2 (b) (c)). Further, when the water-based adhesive is supplied from both the left and right ends of the roll, the central portion is likely to be skinned (FIG. 2 (d)).

Therefore, if one or more humidifier outlets 8 are provided toward the above-mentioned skin-prone portion S of the coating roll surface, skinning can be prevented, and when the effective width of the roll is wide, the humidifier outlet 8 8 may be further provided.

There are various types of humidifiers such as ultrasonic type, vaporization type, etc., but the humidifier used here has an extreme internal temperature of the cover (covering material) provided around the roll portion of the roll coater. The form of humidification is not particularly limited as long as the form is not raised.

Generally, a humidifier called an ultrasonic humidifier vibrates an ultrasonic vibrator in water and sends very fine mist-like water droplets generated on the water surface with the wind from a blower and blows it out from a blowout port. It is a thing.

Further, a humidifier called a vaporization type humidifier or a filter type humidifier sends air to a filter soaked with water, and blows out the moist air to increase the humidity.

Next, an embodiment of the present invention will be described with reference to the drawings and tables.

(D) Example FIG. 1 is an explanatory view of a coating portion of a water-based adhesive double-sided coating machine used as an example of the present invention. Two large and small rubber rolls 2 and 3 sandwiching a guide table 4 are provided. Are arranged side by side so as to be rotatable in contact with each other, and the large upper and lower coating rolls 2 and 2 are arranged so as to approach each other and face each other.

Reference numeral 1 denotes a water-based adhesive, which is filled in a groove formed between the large and small rolls 2 and 3, and an adherend (not shown) is forcibly slid on the table 4 in the direction of the arrow in the drawing. The adherend comes into contact with the upper and lower large rolls 2, 2 and
By rotating the large roll 2 or rotating the large roll 2, the adhesive 1 is applied to both front and back surfaces of the adherend.

Therefore, in the present invention, for example, the upper and lower rolls 2 and 3 are covered with a cover 6 made of a material such as a polyethylene sheet that does not allow air to pass through, and the inside thereof is kept in a windless state. The side surface of the body 6 is provided with an opening sufficient for the adherend to pass through the inside of the coating chamber 9, and
A commercially available humidifier 7 that blows out mist-like water droplets at room temperature is prepared outside, and one or more blowout ports 8 are arranged toward the portion S of the roll surface where the above-mentioned skinning is likely to occur.

The lower end of the upper cover 6 may be bent in a U shape, and a water drop removing unit 9 may be provided so that the water drops attached to the inner surface of the cover can be removed.

Therefore, a polyethylene sheet is used as the covering object 6, and an ultrasonic humidifier made by Toshiba Corporation is used as the humidifier 7, and the upper and lower sides of the compact double-sided glue KD-350 (trade name) made by Kindai On the rolls 2 and 3 of 62% evaporation residue, viscosity 45000cps (2
(5 ° C.) 800 g of vinyl acetate resin emulsion was placed thereon, the coating amount was adjusted to 180 g / m ² , and the system was operated at 25 ° C.

Then, while continuously humidifying, the adhesive 1 on the rolls 2 and 3 was taken out every 20 minutes, and the viscosity at 25 ° C. and the evaporation residue were measured. The results are shown in the table below.

For comparison, the results of measuring the viscosity and the evaporation residue at 25 ° C. of the adhesive under the same conditions as in the above-described examples without using the polyethylene sheet covering 6 and the humidifier 7 (Comparative Example 1 ) And without using the humidifier 7, instead, a high-temperature steam of 100 ° C. or higher generated from the boiler was visually fed into the shield 6 little by little, and the same test as in the above example was conducted. Comparative Example 2) is also shown in the table.

As can be seen from the above table, the increase in viscosity as well as the evaporation residue is very slow in the process of the invention. According to the present example, the temperature inside the shield 6 remained at approximately 25 ° C. even after 120 minutes had elapsed.

Further, in Comparative Example 2, the temperature inside the shield 6 rises to 80 ° C. in only about 1 minute after the start of the test, then rises slightly and reaches 90 ° C. after 10 minutes, and the adhesive on the roll The same bad condition as when the viscosity increased was observed in a part of the rolls, and skin was observed in a part of the rolls, so the test was stopped.

(E) Effect of the Invention The present invention is configured as described above, and can prevent the skin adhesive from being skinned or deteriorated by an extremely simple method, and can cause a decrease in viscosity of the adhesive and a decrease in adhesion speed. Since there is no,
It has good workability and has advantages such as reduction in bonding cost.

[Brief description of drawings]

FIG. 1 is an explanatory view of a coating portion of a double-sided adhesive coating machine as an example of an apparatus used in the present invention, and FIG.
(D) is an explanation showing the relationship between the range through which the adhesive supply port and the adherend (base material) pass and the range S where skinning is likely to occur in the adhesive coating roll, and the position where the humidifier blowout port is arranged. It is a figure. Explanation of symbols 1 ... Water-based adhesive, 2 ... Large roll for coating 3 ... Small roll, 4 ... Guide table 5 ... Rinsing tank, 6 ... Covering object, 7 ... Humidifier 8 ... Humidifier Vessel outlet, 9 ... Water drop removing part 10 ... Pad, 11 ... Adhering material passing range 12 ... Adhesive supply port S ... Part where skinning is likely to occur

Claims (2)

[Claims] 1. When applying a water-based adhesive to an adherend, a roll coater is covered with a non-air-permeable cover around the roll portion, and the portion through which the adherend passes is left open. , At least 1 towards the adhesive-coated surface of the roll in the enclosure
One or more humidifier outlets are provided to prevent the adherend of the roll from passing through at the normal temperature and to directly moisturize the part, thereby preventing the adhesive from being skinned and deteriorated. A method for applying an adhesive, characterized by: 2. A non-air-permeable covering material such as a polyethylene sheet is used to cover the periphery of the coating roll part of a roll coater for applying the water-based adhesive, and the part through which the adherend passes is in an open state. In this case, at least one blowout port of the humidifier provided outside is provided toward the portion of the roll inside the cover that does not pass the adherend, and the lower end of the cover is inside. An adhesive application device, characterized in that it is bent to form a water drop removing portion.