JPH07108148A - Production of aerosol - Google Patents

Abstract

PURPOSE:To dissolve a compressed gas in a stock soln. without increasing the pressure of aerosol at the time of producing an aerosol consisting of a gas having a specified Ostwald coefficient and a liq. by filling the gas in a vessel and injecting at least a part of the liq. into the vessel. CONSTITUTION:The upper opening of the vessel 2 of an aerosol device 1 is sealed by a mountain cap 4 holding a valve assembly 3, and a gas selected from the gases having 0.5-3.0 Ostwald solubility coefficient, e.g. CO2, is filled in the vessel 2 as the compressed gas, i.e., a propellant. When the stock soln. is injected, a stem rubber 8 us pressed and yielded, and the soln. is introduced into the vessel 2 in the form of fog through the valve housing 7 and a slit 10 by utilizing a gap S between the perphery of the stem 5 and the opening of the mountain cap 4. Consequently, The compressed gas is efficiently dissolved in the stock soln. without increasing the pressure in the vessel.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aerosol. More specifically, it relates to a method for producing an aerosol, for example, in which a compressed gas such as a propellant is dissolved in an aerosol stock solution in a container.

[0002]

2. Description of the Related Art A propellant to be filled with an undiluted solution in an aerosol container is particularly a solution as an aerosol (hereinafter referred to as
When spraying (referred to as contents) or discharging in a foamed state, it is necessary to dissolve it in the stock solution. Also,
Dissolving the propellant in this manner is preferable because the propellant in the undiluted solution separates when the pressure in the aerosol container decreases as the contents are used, and the pressure drop is compensated to some extent. The effect of compensating for the gas pressure increases as the later-described Ostwald coefficient increases, and conversely, if it is 0, there is no compensating effect.

Conventionally, when an propellant is dissolved in an undiluted solution at the time of manufacturing an aerosol, a method of injecting a predetermined amount of undiluted solution into a container and then injecting the propellant into the container at high pressure has been adopted. ing. In that case, since the dissolution rate is too low if the stock solution is dissolved only from the free surface, the container is shaken for a while from the start of injection of the propellant to the completion of the injection. Therefore, when the stock solution is first injected, part of the volume of the container is left as a space for the propellant.

[0004]

SUMMARY OF THE INVENTION In the above conventional method,
In order to obtain an aerosol with the desired propellant solubility under a given pressure, it is necessary to inject the propellant at a high pressure well above said given pressure. This is because the pressure decreases as the propellant is dissolved in the stock solution.

This is composed of a propellant having an Ostwald solubility coefficient (hereinafter, simply referred to as Ostwald coefficient) of 1 and a stock solution, and a solution having a container internal pressure of 6.0 kg / cm ² (hereinafter, all gauge pressure). A typical aerosol product having a volume of about 60% of the container volume and a propellant volume of about 40% will be described.

[0006] Here, the Ostwald coefficient is, in short, a gas volume (unit: ml) that can be dissolved in 1 ml of the stock solution under standard conditions (0 ° C and 1 atm), and is represented by only a numerical value. Below the dissolution rate is proportional to the pressure.

Therefore, first, about 6 in the container under atmospheric pressure.
Inject 0% volume of stock solution, then 15.0 kg / c
m ² of propellant must be injected. This is because if the equilibrium pressure (40% volume of propellant and 60% volume of aerosol) in the container is 6.0 kg / cm ² , it will be 40% at first.
The gas pressure P to be injected into the volume is P × 0.4 = 6.0 × 0.4 + (6.0 × 0.6) × 1 to 15.0 kg / cm ² . This can be expressed by the general formula (1) below.

P ₁ = P ₂ × {χ + β (1-χ)} / χ (1) This is because it is assumed that the propellant does not dissolve in the stock solution until the injection of the propellant is completed. Actually, since it slightly dissolves in the stock solution when the propellant is injected, the maximum pressure in the above example is about 14 kg / cm ² which is slightly lower than 15.0 kg / cm ² . However, even a pressure of this level cannot withstand the current general aerosol container. Even if it can withstand, there is a problem such as loosening of the attachment (crimp) of the aerosol valve. Further, even if an attempt is made to use a container that can withstand such high pressure, the manufacturing cost will be greatly increased, and the legal regulations will be further impaired. Moreover, even if the propellant is injected while shaking, the above high pressure (14 kg / c
m ² ). Further, the surface area of the stock solution occupying 60% of the volume in the container does not increase enormously, but the dissolution time becomes long.

Therefore, under the present circumstances, there is also a method in which an aerosol solution is separately prepared by using a large pressure-resistant container and the aerosol solution is sequentially filled into each aerosol container.
Even with this method, there are problems that the facility cost is significantly increased and the number of steps is increased.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a method for producing an aerosol capable of dissolving a compressed gas in a stock solution without significantly exceeding the pressure of the aerosol in the final equilibrium state. Has an aim.

[0011]

The method for producing an aerosol according to the present invention is a method for producing an aerosol comprising a gas and a liquid having an Ostwald coefficient selected from the range of 0.5 to 3.0. After filling the specified amount of gas into
At least a part of the liquid in which the gas is to be dissolved is injected into the container.

When the liquid is injected into the container, it is preferable that the liquid be sprayed and injected. The droplets in the claims include small particles such as fog to water droplets having a normal size. What is gas?
A gas having a critical temperature of 0 ° C. or higher, or a gas that does not liquefy at room temperature (0 to 40 ° C.) and normal pressure (15 atm or less) even if the temperature is 0 ° C. or higher. For example CO ₂ gas,
It is N ₂ O gas, O ₂ gas, N ₂ gas, air or a mixed gas thereof. The liquid means a liquefied gas, a liquid in which an active ingredient is dissolved in a solvent or the like (so-called undiluted liquid), or a mixture thereof.

[0013]

[Function] If a container is filled with gas at a final equilibrium pressure or slightly higher than the equilibrium pressure and then liquid is injected, the volume ratio of liquid to gas is very small at first and the surface area to volume of liquid is small. The gas is easily dissolved because it is extremely large. Therefore, even if the Ostwald coefficient is small and the partial pressure of the gas is not decreased with the dissolution of the gas, the solubility is not significantly decreased.

As described above, since the gas is efficiently dissolved with the injection of the liquid, the pressure does not rise significantly in the process.

Further, when the liquid is injected in the form of droplets, the surface area of the liquid is larger than that of the liquid, so that the dissolution rate is increased, the filling process is shortened, and the pressurization pressure is suppressed very easily. It

By using this production method, an aerosol can be directly produced in a short time in an ordinary aerosol container used as a product by the above-mentioned action.

[0017]

EXAMPLES Next, the manufacturing method of the present invention will be described in detail based on the following examples.

FIG. 1 is a sectional view showing the principal part of an example of an aerosol device used in an embodiment of the manufacturing method of the present invention.
1 is a perspective view showing a valve housing in the aerosol device of FIG. 1, and FIG. 3 is a graph showing an Ostwald coefficient for a mixed solution of CO ₂ gas of ethyl alcohol-water.

A method for directly and efficiently dissolving the propellant in the stock solution and filling the stock solution directly in the aerosol container will be described below.

In FIG. 1, reference numeral 1 is an aerosol device, and an upper end opening of a container 2 is sealed by a mountain cap 4 holding a valve assembly 3.

CO ₂ used as a propellant is contained in the container 2.
And compressed gas (pressure is 6.0 kg / cm ² ) is filled. Of course, it is not limited to 6.0 kg / cm ² , and it can be changed according to the purpose of use and the injection form. A known method may be used to fill the compressed gas. For example, an injection valve may be provided at the bottom of the container 2 to fill from there, or may be pressed through the gap between the periphery of the stem 5 and the opening of the mountain cap 4, and further pressed through the passage 6 of the stem 5. You may.

Next, the stock solution is press-fitted through the gap S between the periphery of the stem 5 and the opening of the mountain cap 4 as described above.

As shown in FIG. 2, the housing 7 of the valve assembly 3 has a plurality of vertical slits 10 formed in the outer peripheral edge of a circular recess 9 for accommodating a ring-shaped packing (hereinafter referred to as a stem rubber) 8. . Therefore, FIG.
Normally, the stem rubber 8 as shown by the solid line in
Is pressed against the lower surface of the mountain cap 4 and is sealed. However, when the stock solution is pressed in from above as described above, the portion of the stem rubber 8 corresponding to the slit 10 is changed as indicated by the chain double-dashed line in FIG. Bend down. As a result, the undiluted solution is poured into the container 2 in a shower-like manner through the narrow gap S between the stem rubber 8 and the outer peripheral edge of the housing 7. When injecting, the pressure of the stock solution upstream of the stem rubber 8 is the pressure inside the container (6.0 kg / cm ² ).
Although it is made higher, when it enters the container 2 through the gap S, it expands and its pressure is 6.0 kg / cm.
It drops to about ² . Moreover, since the undiluted solution is in the form of a large number of small droplets, the surface area with respect to its volume is extremely large (compared to the free surface of the undiluted undiluted solution), and the volume ratio of undiluted solution to the compressed gas in the container 2 is extremely large. Since it is small, the compressed gas dissolves in each droplet in a short time.

Therefore, the dissolution rate is extremely high even without shaking, and the internal pressure of the container does not rise much when the stock solution is injected. Of course, it is preferable to perform the shaking at the same time because the dissolution rate further increases when the stock solution injection amount increases.

Finally, about 6.0 kg / c, which is almost the same as the pressure immediately after gas filling (hereinafter referred to as the initial gas pressure).
An equilibrated aerosol is obtained at m ² . Thus, when the Ostwald coefficient is 1, the initial gas pressure and the final equilibrium pressure are theoretically the same. However, if the Ostwald coefficient is different, this relationship is also different. The relational expressions are shown below.

P ₁ = P ₂ {χ + (1-χ) β} (2) where P ₁ is the initial gas pressure (kg / cm ² ), P ₂ is the final equilibrium pressure (kg / cm ² ), χ Is the final volume ratio of the gas in the container, and β is the Ostwald coefficient.

In the relational expression (2) and the relational expression (1) in the conventional manufacturing method, for example, the equilibrium pressure (P ₂ ) usually used as an aerosol device is 6.0 kg / cm ² , and the final gas volume ratio is 0.4. And the Ostwald coefficient β is 0, 0.5, 1.0, 1.5, 2.0, 2.
Table 1 shows the initial gas pressures in the cases of 5 and 3.0.

[0028]

[Table 1]

As shown in Table 1, according to the manufacturing method of this embodiment, the initial gas pressure can be suppressed to be extremely low as compared with the conventional manufacturing method. This effect becomes even greater when the final gas volume ratio is small.

Therefore, according to such a manufacturing method, the propellant can be dissolved in the stock solution directly in the aerosol container, and in a very short time.

In the above embodiment, the compressed gas for propellant was described as an example of the gas to be injected, but the method of using the gas is not limited to the propellant. For example, the action of producing the injection pressure and adjusting the pH of the stock solution using, for example, CO ₂ may be performed.

In the present invention, the Ostwald coefficient is 0.5 to
Although it is limited to the range of 3.0, the reason is that when the Ostwald coefficient exceeds 3.0, the initial gas pressure becomes high even by the production method of the present invention, and the aerosol is generated using the existing aerosol container. This is because it is not preferable to manufacture it, and on the other hand, if the Ostwald coefficient is less than 0.5, it is not necessary to increase the initial gas pressure even by the conventional manufacturing method.

The stock solution to be injected after filling the compressed gas does not have to be all of them. For example, a method may be used in which a small amount of the stock solution is first injected, then a compressed gas is filled, and finally the remaining stock solutions are all injected. As such a manufacturing method, for example, when using a stock solution mainly consisting of water and ethyl alcohol, such as a hair restorer, water in which CO _{2 as a} propellant is difficult to dissolve is first injected, and then the propellant is injected. For example, when injecting ethyl alcohol in the form of a shower later, this applies.

The numerical values shown in Table 1 above are theoretically calculated. Next, an example in which a compressed gas is dissolved in a stock solution by the manufacturing method according to the above-described example will be described.

[0035] Using 60 wt% of ethyl alcohol and 40% by weight of water as an example stock, the CO ₂ is used as the compressed gas, at ambient temperature of 25 degrees Celsius, CO ₂ in the aerosol container volume shown in Table 2 Was injected at the pressure shown in Table 2, and
A test was carried out in which the stock solution having the volume shown in was injected in a shower shape.

[0036]

[Table 2]

CO _{2 at} a test temperature of 25 ° C.
The Ostwald coefficient for the above-mentioned undiluted solution was 1.3 when read from the graph of FIG. 3 obtained by the inventors' experiments.
It is a degree. According to the test, the pressure in the container reached the equilibrium pressure without exceeding the initial gas pressure during the process of injecting the stock solution.

[0038]

According to the production method of the present invention, when a gas is dissolved in a liquid, the final equilibrium pressure is not significantly exceeded and the gas is dissolved in a short time to reach an equilibrium state. Therefore, for example, the aerosol can be manufactured in an aerosol container used as a product, and a separate large pressure-resistant container is not required.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part showing an example of an aerosol device used in a manufacturing method of the present invention.

FIG. 2 is a perspective view showing a valve housing in the aerosol device of FIG.

FIG. 3 CO ₂ for ethyl alcohol-water mixture
It is a graph which shows the Ostwald coefficient of gas.

[Explanation of symbols]

 1 Aerosol Device 2 Container 3 Valve Assembly 4 Mountain Cap 5 Stem 6 Passage 7 Housing 8 Stem Rubber 10 Slit S Gap

Claims (2)

[Claims] 1. A method for producing an aerosol comprising a gas and a liquid having an Ostwald coefficient selected from the range of 0.5 to 3.0, the method comprising: filling a container with a predetermined amount of gas; A method for producing an aerosol, which comprises injecting at least a part of a liquid in which a gas is to be dissolved into a container. 2. The method for producing an aerosol according to claim 1, wherein when the liquid is injected into the container, the liquid is sprayed and injected.