Aerosol container

Abstract: An aerosol container in which a valve cap of the aerosol container is fitted into an opening of the container, wherein a raw material for forming the aerosol container is a high molecular compound having a glass-transition temperature of 74°C to 100°C, is provided. Thereby, the valve cap and the contents are not scattered out of the aerosol container, event if the internal pressure of the aerosol container is elevated.

Description: BACKGROUND OF THE INVENTION Field of the Invention: The present invention relates to an aerosol container in which a valve cap is fitted into an opening at the neck and particularly, to a raw material which is used for producing the aerosol container. Prior Art: Conventionally, an aerosol container in which a valve cap is fitted into an opening at the neck, the one having such a structure as shown in a cross-sectional view of Figure 2 is disclosed in, for example, Japanese Patent KOKAI (Laid-Open) No.76993/88. This structure is the one in which ring recess (3) is formed on the neck of the container body (1); and valve cap (7) is fitted into the above-mentioned neck region (2) and the lower end (8) of the valve cap (7) is narrowed down into the above-mentioned recess (3), wherein valve housing (5) for valve (4) extending into the inside of the container, is airtightly supported with sealing member (6). Regarding such an aerosol container, a high pressure-resistant property is requested for the container in itself, so that a resin such as polyethylene terephthalate is commonly used in the form of a single substance for a raw material of the container. However, since such an aerosol container is produced taking into consideration only the pressure-resistant property of the container in itself, the pressure-resistant effect of the container in itself is elevated rather than the engagement force of the valve cap. There has been the disadvantage that when the aerosol container was left as it is, for example, in a car as parked under the blazing sun, the container in itself is not bursted, but the engagement region is broken, so that the contents are jetted out from the container body while the valve cap is explosively scattered out. SUMMARY OF THE INVENTION It is an object of the present invention to provide an aerosol container, out of which a valve cap and contents therein are not explosively scattered even if an internal pressure of the aerosol container is elevated, while a high pressure-resistant property of the container in itself is maintained. According to the present invention, there is provided an aerosol container in which a valve cap is fitted into an opening at the neck of the aerosol container, characterized in that the raw material forming the aerosol container is a high molecular compound having a glass-transition temperature of 74°C -100°C. In the aerosol container of the present invention, when the internal pressure thereof has come up to such a degree as the contents would be exploded, the aerosol container is expanded in itself to lower the internal pressure, so that a burst of the container can be avoided. In order to provide such a function, the glass-transition temperature of a raw material for the aerosol container is set in the range of 74 °C to 100°C, preferably 75°C to 85°C. When this glasstransition temperature is less than 74°C, the container is easily expanded in itself, while when the temperature is more than 100°C, the container is not expanded since the container is hard in itself. In this respect, when the container is produced, the bottom region thereof is little drawn, so that the bottom region is provided with a lower strength as compared with other regions, and thus, it causes the result that the bottom region having a lower pressure-resistant property is exploded. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic elevation view of an aerosol container which is used for working examples and comparative examples of the present invention; and Figure 2 is a longitudinal section view in which elements in and around the opening of a conventional aerosol container are shown on an enlarged scale. DETAILED DESCRIPTION OF THE INVENTION As a raw material forming the aerosol container of the present invention, a high molecular compound having the above-mentioned glass-transition temperature can be properly selected and employed. For example, polycarbonate, poly(ethylene naphthalate), polysulfone, polyethersulfone, a mixture of polyethyleneterephthalate (PET) and polyarylate (PAr) and the like can be exemplified. Preferably, it is the mixture of PET and PAr, wherein a mixture ratio of PET to PAr by weight % is preferably 60:40 to 95:5, more preferably 80: 20 to 95:5 by weight %. If the compounded content of PAr is too little, the ability to engage between the aerosol container and the valve cap thereof is decreased, while if the compounded content of PAr is too much, the container comes to be difficult to expand in itself, so that the bottom region having a low pressure-resistant property is bursted out. Then, as a method of forming the aerosol container of the present invention, a biaxial stretching blow-molding hot-parison method is commonly used. This method comprises feeding a parison obtained through an injection molding while its hot state, to a rcheating process without staying, followed by forming and thereafter, mechanically drawing the parison in a longitudinal direction while the parison is maintained at a constant temperature in a blow-die; and at the same time or in succession, blowing a pressed air into the blow-die so as to expand the parison in a circular direction (or in a transverse direction). Furthermore, there is a method of forming an aerosol container which comprises forming the engaged region of the valve cap on the periphery of the opening according to a non-stretching injection molding; and forming a body of the container which is filled with contents, according to a stretch blow-molding. According to such a stretch blow-molding, the longitudinal drawing of the body and the transverse drawing thereof are controlled to a low stretch ratio of 1.00 to 1.15 times and 1.90 to 2.20 times, respectively, and thereby, the container can be deformed and expanded under a high pressure following a temperature elevation of the contents and thus, the thickness thereof can be thinned so as to lower the internal pressure. With respect to the contents which an aerosol container of the present invention can be filled with, conventionally known ones can be employed. As the contents, for example, human-body articles, domestic articles, industrial articles can be exemplified. As for human-body articles, there are hair articles, cosmetics, odor-removing/sweat-repressing agents and other human-body articles; as for domestic articles, there are insecticides, coating agents, cleaners, foods and other domestic articles; and as for industrial articles, there are automobile articles and other industrial articles. As for the above-mentioned hair articles, there are hairsetting sprays, hairdressing conditioners, hair shampoos, rinses, acid wool-dyeing agents, oxidizing two-agent type permanent wool-dyeing agents, color sprays, decoloring agents, permanent-wave agents, hair-growing agents and the like. As cosmetics, there are shaving creams, aftershave lotions, perfumes, eau de Cologne, face-cleansing agents, anti-suntan agents, foundations, dehairing/decoloring agents, bath agents, dentifrice agents and the like. As the odor-removing/sweat-repressing agents, there are odor-removing agents, sweat-repressing agents, body shampoos and the like. As other human-body articles, there are muscle-antiflash agents, skin-trouble agents, medicines for a dermatophytosis, other medicines, injurious-insect repellents, cooling agents, cleaning-wiping agents, agents for oral-cavity and the like. As insecticides, there are space insecticides, insecticides for a cockroach, gardening insecticides, insecticides for a tick, insecticides for an uncomfortable insect and the like. As coating agents, there are domestic paints, automobile paints, undercoating agents and the like. As cleaners, there are domestic cleaners for glass, lens cleaners, carpet cleaners, bath cleaners, lustering cleaners for a floor/furniture, shoe/leather cleaners, wax lustering agents and the like. As other domestic articles, there are indoor odor-removing agents, toilet odor-removing agents, waterproofing agents, washing starches, herbicides, clothing insecticides, flameproofing agents and the like. As automobile articles, there are defogging agents, thawing agents, engine-starting agents, puncture-repairing agents, engine cleaners and the like. As other industrial articles, there are lubricating/anti corrosive agents, adhesive agents, metal deep-cut agents, mold releasing agents and the like. As the forms of the above-mentioned contents, a liquid, a fluid state, a semi-solid state, a foam state, a gaseous state, as well as a mixture of each of the above-mentioned states and a little solid in a powder state or a particle state, and the like can be properly selected and employed. The above-mentioned contents can include a material which has been conventionally employed as an additive agent. As such an additive agent, alcohol; a synthetic resin; a propellant (a simple substance selected from the group consisting of LPG (liquefied petroleum gas), DME (dimethyl ether), N 2 CO 2 and the like, or a mixture thereof); cellulose; ammonium; water; perfumes; dyes; surface active agents; pigments are properly selected and added thereto. For example, some of the above-mentioned hair sprays include a denatured alcohol and LPG for the propellant as main components, to which an acrylic resin alkanolamine liquid, polyoxyethyleneoleyl ether, a perfume and the like are added, while some of the above-mentioned hair treatments include the denatured alcohol and LPG for the propellant as main components, to which a liquid paraffin, propylene glycol, methylphenyl polysiloxane and a perfume are added. [Working Examples] Hereinafter, Working Examples of the present invention will be in detail explained referring to the Drawings and Tables. Working Examples 1-5 and Comparative Examples 1-2: An aerosol container shown in Figure 1 has a content volume of 97ml and a weight of 30g, wherein reference numeral (10) is an opening of the aerosol container, which is an engagement region for engaging a valve cap (which is not shown in Figure 1), and reference numeral (11) is a body for retaining contents therein. The aerosol containers were formed according to a biaxial stretching blow-molding hot-parison method, after mixing PET and PAr in mixing ratios as shown in Table 1. As the stretching conditions in the parison, a preheating temperature of 140 °C to 165°C and a heating time of 20 seconds were employed at a heating position, while a blow-die temperature of 20°C, a blow-pressure of 20 to 35kgf/cm 2 and a blow-time of 10 to 15 seconds were employed at a stretching position. The stretch ratio of the body of each of bottles were 1.1 times in the longitudinal direction and 2.0 times in the transverse direction. With respect to the item "Evaluation at Temperature Elevated to 80°C " in Table 1, each of the aerosol containers was filled with contents and an aqueous solution containing LPG (liquefied petroleum gas) under the conditions of an ordinary temperature (about 25°C ) and an internal pressure of 6kg/cm 2 and then, a valve cap as shown in Figure 2 was fitted into the opening. Supposing the inside of an automobile car as parked under the blazing sun, an environmental temperature was elevated from an ordinary temperature (about 25 °C ), and after the temperature reached 80°C, the temperature of 80°C was maintained for a period of eight hours, and then it was visually evaluated whether an engagement region which is positioned on the periphery of the opening of each of the aerosol containers had been broken or not. The composition of contents used here are as follows: <Hair Spray> Weight% Acrylic Resin Alkanolamine Liquid (3%) 4.00 Polyoxyethyleneoleyl Ether 0.01 Triethanolamine 0.50 Perfume 0.17 Denatured Ethyl Alcohol of 99% 55.32 LPG 40.00 100.00 PET wt.% PAr wt.% Glass Transition Temperature Evaluation at Temperature Elevated to 80°C Comparative Examples 1 100 0 73 Engagement Region was Broken at 75°C in Middle of Elevation Working Examples 1 95 5 75 Not Broken 2 88 12 78 Not Broken 3 80 20 81 Not Broken 4 68 32 88 Not Broken 5 60 40 95 Not Broken Comparative Examples 2 50 50 102 Occurrence of Burst at Container Bottom As shown in Table 1, when the ratio of PET:PAr by weight % is in the range of 60:40 to 95:5, the above-mentioned engagement region was not broken, and the containers were not burst as well, while when the ratio of a polyarylate is 50% (Comparative Example 2), the container's bottom having a low pressure-resistance was bursted. Working Example 6 and Comparative Example 3: Aerosol containers which were produced in the same mixing ratios as the ones in the Comparative Example 1 and Working Example 1 were filled with the same contents under an internal pressure of 6 kg/cm 2 , respectively, and the environmental temperature was elevated. At this time, the temperature of vapor phase in the aerosol containers, the temperature of liquid-phase in the aerosol containers, the internal pressure in the aerosol containers, and the visual evaluation as to whether the engagement regions were broken are shown in Table 2. PET/PAr Mixing Ratio Temperature-Elevating Time (min.) Environmental Temperature (°C) Vapor-Phase Temperature (°C) Liquid-Phase Temperature (°C) Internal Pressure (kg/cm 2 ) Evaluation of Engagement Region Comparative Example 3 0 33 29 25 6.2 All Right 70 75 69 57 13.3 All Right 75 76 71 59 12.3 Engagement Region was Broken Working Example 6 0 36 35 33 6.9 All Right 70 72 65 57 12.8 All Right 80 76 71 61 13.6 All Right 90 80 75 66 10.8 All Right 120 80 76 73 5.5 All Right As shown in Table 2, the engagement region was not broken by using a aerosol container-forming raw material composed of a mixture of polyarylate with polyethylene terephthalate, even if a vapor-phase temperature is 71°C, and an internal pressure is in the range of 12 to 13kg/cm 2 . This is, because the container was expanded in itself, and its thickness was thinned, and thereby, the internal pressure was decreased. [Effect of the Invention] According to the present invention, an aerosol container in which a valve cap is fitted into an opening of the container, is produced to have a glass transition temperature of a raw material of the aerosol container in the range of 74 °C to 100°C, and thereby, such an effect that the aerosol container in itself maintains a high pressure resistance, while even if the internal pressure of the aerosol container is increased, the valve cap or the contents there of are not explosively scattered out of the container can be provided.

Claims: An aerosol container in which a valve cap (7) is fitted into an opening (10) at the neck of the container, characterised in that the raw material for forming said aerosol container is a high molecular compound having a glass-transition temperature of 74° C to 100° C. The aerosol container according to claim 1, wherein said high molecular compound is selected from the group consisting of polycarbonate, poly(ethylene naphthalate), polysulfone, polyethersulfone, and a mixture of polyethylene terephthalate and polyarylate. The aerosol container according to claim 1, wherein said high molecular compound is a mixture of polyethylene terephthalate and polyarylate. The aerosol container according to claim 3, wherein a mixing ratio of a mixture of polyethylene terephthalate and polyarylate by weight % is in the range of 60:40 to 95:5. An aerosol container according to claim 1, wherein the body (11) of said aerosol container is formed under the conditions of a longitudinal drawing of 1.00 to 1.15 times, and a transverse drawing of 1.90 to 2.20 times according to a stretch blow-molding.

Inventors: HABU YOSHITAKA, HACHINOHE YUKIO, HIRATA MITSUTO, KISHIDA KOJI, MITSUI TOSHIYUKI, SATO TETSUYA, TSUNODA SHINICHI, YAMAMOTO KATSUHIKO, HABU, YOSHITAKA, HACHINOHE, YUKIO, HIRATA, MITSUTO, KISHIDA, KOJI, MITSUI, TOSHIYUKI, SATO, TETSUYA, TSUNODA, SHINICHI, YAMAMOTO, KATSUHIKO
Applicants: TOYO AEROSOL IND CO, TOYO KAGAKU KK, TOYO AEROSOL INDUSTRY CO., LTD., TOYO CHEMICAL CO., LTD.
Application year: 1998
Main classification: B65D83
IPC codes: B65D83, B05B9