JPS6310745B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of applying a foamable adhesive. In general, when adhesives are used to bond porous or highly uneven surfaces, such as foamed urethane or cloth, the adhesive strength is not sufficiently exerted. Since the adhesive flows into the gaps and recesses, it usually requires several times the amount to be applied than when bonding a smooth surface, and it also has the disadvantage that it is difficult to spread. Therefore, in recent years, a technology has been proposed in which the adhesive is foamed using a foaming mixer in a stirring container to prevent the adhesive from being absorbed and to make it easier to spread. It is necessary to add a foaming agent, which causes a decrease in adhesive performance.
In addition, it is necessary to foam immediately before application, and it must be stirred repeatedly. Furthermore, although the foamed adhesive is difficult to handle, it must be scooped out of the stirring container and applied, making the application process complicated. Moreover, in this type of foaming method, uneven foaming tends to occur within the stirring container, and uneven adhesion may occur. Particularly when applied to a vertical surface, uneven stirring may cause dripping. Furthermore, when pasting wallpaper onto a wall surface, the surface of the wallpaper will generally become uneven after pasting unless the adhesive layer is thinned. However, in actual practice, it is extremely difficult to apply adhesive thinly enough to give a beautiful finish to a wall or wallpaper, and it requires a great deal of effort and time. For this reason, there are commercially available wallpapers with adhesive or rewetting active adhesive applied to the back side of the wallpaper in advance, but once the adhesive type sticks, it cannot be repaired, and the rewetting active type Things also have to be soaked in water once, which is cumbersome. Under these circumstances, we conducted various research in order to obtain a foaming adhesive that exhibits uniform foamability, can be applied directly and uniformly to the adhered surface, and can be applied thinly or thickly. As a result, they discovered that when an emulsion-type water-based adhesive is sealed in a pressure-resistant container together with a propellant at a fixed ratio, and the propellant is jetted out of the pressure-resistant container together with the adhesive, uniform foaming of the adhesive is formed. The present invention has now been completed. Conventionally, aerosol-type adhesives have been known, but in all of them, the adhesive is sprayed in the form of a mist. In particular, an emulsion-type water-based adhesive and a propellant are sealed in a pressure-resistant container and then sprayed out. It was discovered for the first time by the present inventor that a uniform foamable adhesive can be obtained by this method. An object of the present invention is to provide a method for applying a foamable adhesive, which comprises sealing an emulsion-type water-based adhesive and a propellant, preferably liquefied propane and/or liquefied butane, in a pressure-resistant container. Such foamable adhesives are foamed when the propellant is injected with the adhesive into the outside of the pressure container through the nozzle, so if the adhesive is injected toward the surface to be adhered, the adhesive will be directly exposed. A foamed adhesive can be applied to the surface. Therefore, the present invention involves sealing an emulsion-type water-based adhesive together with a propellant in a pressure-resistant container at a fixed ratio, and spraying the adhesive together with the propellant from a nozzle of the pressure-resistant container to directly apply the adhesive to the surface to be adhered. The present invention provides a method for applying a foamable adhesive by forming and applying it in the form of a foam. In particular, the volume ratio of adhesive and propellant varies depending on the type and viscosity as shown below, but when using commonly used adhesives, in order to form uniform foam, it is necessary to Based on the current propellant, a range of 90:10 to 70:30 is particularly desirable. In this range, the adhesive is ejected from the nozzle in the form of a string or broken strings, adheres to the surface of the adherend, and then foams. In this case, the nozzle can be applied from a distance without having to bring the nozzle close to the adherend, so it is possible to improve the efficiency of coating work on adherends such as walls. It should be noted that if the adhesive component exceeds the above range, sufficient foamability cannot be obtained, and if it is less than this, the adhesive will be sprayed in a mist form, which is not preferable. As the adhesive component used in the present invention, it is possible to use an aqueous solution adhesive in addition to an emulsion-type water-based adhesive. It is easy to obtain uniform foaming and does not drip easily when applied to vertical surfaces. Furthermore, with the same viscosity, emulsion-type water-based adhesives can have a higher solids content, making it easier to control the discharge amount and making it easier to spread when applied. From these points of view, it is preferable to use an emulsion type water-based adhesive. As the emulsion type water-based adhesive, polyacrylic emulsion or polyvinyl acetate emulsion is used. These water-based emulsion-type water-based adhesives may optionally contain various surfactants, rosin, modified phenolic resins, terpenes, petroleum resins, tackifiers such as coumaron indene resin, calcium carbonate, clay, silica, and asbestos. fillers, higher alcohols, glycols, plasticizers such as phthalate esters, colorants such as titanium white and other dyes and pigments, antioxidants, antifungal agents, and the like may be added. Usually, solid content including these additives
15-75% is used. Examples of propellants used in the present invention include propane, butane, chlorofluorocarbons, carbon dioxide, dimethyl ether, nitrogen, and mixtures thereof, but the propellant and adhesive can separate into two layers in a pressure-resistant container. Therefore, in order to discharge the adhesive to the end without wasting it, it is better that the specific gravity of the liquefied propellant is lower than that of the adhesive, and in order to maintain the stability of the adhesive and increase bubble generation, the propellant should be water-resistant. It is better not to blend in. From this point on, liquefied propane, liquefied butane or liquefied Freon or mixtures thereof are used. A foamable adhesive can be constructed by appropriately combining the above adhesive and a propellant at the above-mentioned volume mixing ratio. The foamable adhesive is sealed in a pressure-resistant container as shown in FIG. 1 in a conventional manner. FIG. 2 is a top sectional view of the pressure-resistant container shown in FIG. 1. The aluminum container 1 is formed by wrapping a lid 1b around the opening of a barrel 1a. An injection member 2 is attached to the center of the lid 1b. The injection member 2 has a stem rubber 4 attached to the upper end opening of an annular housing 3, and a stem 5 having a flow path 5a through a central hole of the rubber.
is inserted into the housing 3 and urged upward by a spring 6 provided at the inner bottom of the housing. A push button 7 having an open beak-shaped nozzle portion 7a is attached to the upper end of the stem 5. On the other hand, there is an opening at the bottom of the housing 3, which communicates with a stand pipe 8 extending below the container. Therefore, when the push button 7 is pressed down, the inlet of the flow path 5a of the stem 5 is released from contact with the stem rubber 4, and the injection member 2 is placed in an open state (see FIG. 3). The adhesive A is foamed by the propellant B and is sprayed to the outside through the nozzle portion 7a. After applying the foamed adhesive to the surface to be adhered, the adhesive layer can be flattened using a cap 10 that also serves as a spatula, as shown in FIG. The cap 10 which also serves as a spatula includes a spatula section 12 on the upper part of a cap section 11, and a wide wave-shaped end section 12a is formed at the upper end of the spatula section 12. In use, the cap part 11 can be used as a gripping part (see FIG. 4). FIG. 5 shows the state of foam application using another embodiment of the pressure container, in which the nozzle portion 7a of the press button 7 has a small diameter, and this allows the adhesive to foam on the application surface, making it possible to apply from a distance. It has the advantage of being able to According to the present invention, a foaming adhesive can be constructed by sealing a water-based emulsion type adhesive together with a propellant in a pressure-resistant container. There is no need for the complicated work of putting the adhesive in a stirring container, foaming it with a foam mixer, scooping it out, and applying it. Simply point the nozzle of the pressure container toward the surface to be adhered, and press the press button. The foamed adhesive is discharged and applied to the adhered surface, making the application process extremely simple. Furthermore, since the adhesive is applied in a foamed state, it will not absorb into porous, fibrous, or uneven surfaces. Furthermore, since it can be easily spread, a thin and wide adhesive layer can be formed with a small amount of adhesive. Furthermore, since the adhesive forms a foam, the drying speed can be adjusted appropriately, and even if the adhesive is applied thickly or unevenly, the air bubbles will occupy most of the volume, making it completely unnoticeable after drying. Suitable for bonding a wide range of surfaces such as
Furthermore, even if it protrudes during application, since it is a foam, it is easy to remove and becomes unnoticeable once it dries.
Furthermore, since it becomes a mist and does not scatter, there are no health and safety problems. In addition, the size of the nozzle discharge port can be freely selected depending on the discharge amount, from a narrow spray type to a wide-mouth type for shaving cream, and a relatively large amount of propellant is sealed in a pressure-resistant container. It has various advantages, such as almost no nozzle clogging unlike conventional aerosol adhesives. Hereinafter, the present invention will be explained in more detail based on Examples. Example 1 Polyacrylic emulsion (Acronal 80D manufactured by Yuka Vadish Co., Ltd.) 90 parts (volume) Liquefied propane-butane mixture (volume ratio 40:60)
10 parts Each of the above components is placed in the same aluminum pressure container and shaken well for 5 minutes to obtain a foamable adhesive. (Foaming ratio: 16 times) Example 2 Polyvinyl acetate emulsion (Vinizol #210 manufactured by Daido Kasei Kogyo Co., Ltd.) 77 parts Water 13 parts Liquefied Freon 10 parts The above components were placed in the same aluminum pressure-resistant container and shaken well for 5 minutes. to obtain a foamable adhesive. (Foaming ratio: 18 times) Example 3 Example 1 was applied on one side of plywood (100 x 100 x 5 mm).
Discharge the foaming adhesive of 2 from a pressure container, apply a foaming adhesive layer with a width of 3 cm in a single strip,
A canvas (100 x 100 mm) was pressed onto it and left as is for 24 hours, and the peel adhesion strength of the canvas was measured. On the other hand, Acronal 80D
Then apply Vinizol #210 to one side of the same plywood with a brush, press the same canvas as above on top of it, leave it as it is for 24 hours, measure the peel adhesion strength of the canvas, and report the results below. It is shown in Table 1.

[Table] From the above results, when the coating amount is the same, the foamable adhesive exhibits approximately twice the adhesive strength. This is because absorption of the adhesive between the fibers is prevented, and the amount of adhesive substantially involved in adhesion is greater than when foaming is not performed. Example 4 The foamable adhesive of Example 1 was applied onto mortar (100 x 100 x 10 mm) by discharging it from a pressure container, and
Wallpaper (100 x 100 mm) was pressed onto it and adhered in the same manner as in Example 3. Meanwhile, apply Acronal 80D to the same mortar with a brush and press the same wallpaper to adhere. The peel adhesion strength of both was measured. The results are shown in Table 2 below.

[Table] As is clear from the above results, in the case of foam application of the foamable adhesive of Example 1, there was no difference in adhesive strength depending on the difference in application amount, whereas Acronal 80D
In the case of brush application, the adhesive strength increases as the application amount increases, but even an application amount of 150 g/m ² does not reach the adhesive strength of the foam coating of the present invention with an application amount of 100 g/m ² . This is because in the case of brush application, the adhesive is absorbed into the mortar surface and the amount of adhesive involved in adhesion is substantially reduced, whereas in the case of foam application, the amount absorbed by the mortar surface is hardly reduced. This is because it can be spread thinly and efficiently on the mortar surface, making it easy to obtain maximum adhesive strength with the minimum amount of application.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a pressure-resistant container used in the present invention;
2 and 3 are sectional views of the top of the pressure vessel shown in FIG. 1 with the cap removed; FIG. 2 shows the injection member in the closed state, and FIG. 3 shows it in the open state. FIG. 4 is a perspective view showing the state in which the spatula cap of the pressure container shown in FIG. 1 is used. FIG. 5 is a diagram showing a state of foam coating using another embodiment of the pressure container. 1...Pressure container, 2...Injection member, 7a...
Nozzle part, 10... Cap that also serves as a spatula, A... Adhesive, B... Spraying agent.

Claims (1)

[Claims] 1. An emulsion-type water-based adhesive selected from polyacrylic emulsion or polyvinyl acetate emulsion and a propellant selected from liquefied propane, liquefied butane, liquefied fluorocarbon, or a mixture thereof, in a volume mixing ratio of a propellant in a liquid state. 90:10 to 70:30 based on the ratio of 90:10 to 70:30, and the adhesive is sprayed from the nozzle of the pressure container together with the propellant to form a foam directly on the surface to be applied. A method for applying a foamable adhesive, characterized by: