JPH0442343B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a glass bottle that indicates the deterioration of the contents, which is suitable as a container for foods and drinks that are easily deteriorated by ultraviolet rays, such as sake.

(Conventional technology) Glass bottles do not allow oxygen or moisture to pass through, and there is no risk of elution of metal ions that can affect food and drink products. It is an extremely excellent container for packaging products. However, this transparency has the disadvantage that it is easy for light to pass through it, making it easy for the contents to be deteriorated by light, especially ultraviolet rays. For this reason, there are glass bottles, such as beer bottles, that sacrifice transparency and are colored dark brown to prevent the transmission of ultraviolet rays, but it is almost impossible to see the contents. On the other hand, when a transparent glass bottle is used to clearly see the contents, it is impossible to avoid the possibility that the contents will gradually change in quality due to exposure to ultraviolet rays during the distribution stage and the taste will deteriorate. However, since it is difficult for consumers to distinguish this from the appearance, they sometimes mistakenly purchase products that have deteriorated in taste.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems and prevents consumers from deteriorating the contents due to ultraviolet rays during the distribution stage without sacrificing the advantage that the contents are clearly visible from the outside. This was done in order to provide a glass bottle that displays the possibility of deterioration of the contents.

(Means for Solving the Problems) The present invention provides V ₂ O ₅ of 0.01 to 1.0% by weight and 0.05
It is made of soda lime glass containing ~0.5% CeO ₂ and is characterized by the fact that only the surface layer gradually changes color to purple depending on the amount of ultraviolet irradiation, alerting consumers to the possibility of deterioration of the contents. It is something to do.

In the present invention, a glass containing V ₂ O ₅ and CeO ₂ , which are components that cause a change in color tone due to ultraviolet rays, is added to a normal soda lime glass composition. Vanadium and cerium usually exist in glass as V ⁵⁺ , V ³⁺ , Ce ³⁺ , and Ce ⁴⁺ ions, but when exposed to ultraviolet light, only the surface layer exposed to ultraviolet light undergoes a chemical change as shown in the following formula. arise.

Ce ³⁺ +V ³⁺ →Ce ⁴⁺ +V ²⁺ and V ³⁺ exhibits a faint pale green color, while V ²⁺ exhibits a purple color, and moreover, the color changes depending on the cumulative amount of ultraviolet light.
As the amount of V ²⁺ gradually increases, the glass gradually becomes darker purple in color. This phenomenon has been known to those skilled in the art for a long time as solarization of glass, but it has traditionally been understood as an undesirable phenomenon that causes discoloration of glass. I felt that the purpose of the research was focused on whether it was possible to prevent the progression of re-growth. The present invention is novel in that it effectively utilizes solarization and serves as a means for consumers to know the cumulative amount of ultraviolet light that a glass bottle has received before reaching the consumer's hands. It is something.

In order to display the integrated light amount as described above, V ₂ O ₅ must be present in the soda lime glass composition.
It is necessary to use a glass having a composition range of 0.01-1.0% and 0.05-0.5% of _CeO2 . Here V ₂ O ₅
When V 2 O 5 is less than 0.01%, the discoloration does not appear clearly, and conversely, when V ₂ O ₅ is more than 1.0%, the original glass has a strong yellow-green color, and the change in color tone upon irradiation with ultraviolet rays becomes visually difficult to distinguish. Furthermore, if CeO ₂ is less than 0.05%, the discoloration will be unclear, and conversely, if CeO ₂ is more than 0.5%, the absorption of ultraviolet rays will be too large.
The discoloration occurs only in a very shallow part of the surface layer of the glass bottle, making the apparent discoloration even more difficult to notice.

Further, in the present invention, the basic glass composition is limited to soda lime glass because other glasses lack practicality as glass bottles. The thickness of the body of the glass bottle is preferably within the range of 1 to 10 mm. This is because if it is less than 1 mm, it will not be possible to maintain the required strength as a glass bottle, and if it is more than 10 mm, the discoloration in the entire wall thickness direction will not be noticeable.

As described above, the glass bottle of the present invention can be manufactured by melting, forming, and slowly cooling a glass containing a predetermined amount of V ₂ O ₅ and CeO ₂ in a normal soda lime glass composition using a conventional method. It has the function of informing consumers of the cumulative amount of ultraviolet rays received during the subsequent distribution process as a change in surface area. Therefore, by being careful not to purchase discolored glass bottles, consumers can avoid products whose contents may have deteriorated in quality and taste. Note that such discoloration can be reversed by heating, so when reusing glass bottles collected from the market, it is sufficient to heat them.

(Example) Example 1 SiO ₂ 71.5% (weight %, same hereinafter), Al ₂ O ₃ 2.0%,
Fe ₂ O ₃ 0.05%, CaO 10.5%, Na ₂ O 14.0%, K ₂ O 1.5
%, CeO ₂ 0.30%, and V ₂ O ₅ 0.12% soda lime glass was melted and molded by a conventional method to produce a glass bottle with a body wall thickness of 3.0 mm. This glass bottle shows A in Figure 1 before being irradiated with ultraviolet light.
As shown in , it shows uniform transmittance over most of the wavelength range of visible light, and a slight decrease in transmittance in the wavelength range of 590 to 680 nm gives it a pale green color tone. Therefore, the contents can be clearly seen from the outside, similar to a colorless and transparent glass bottle. Next, this glass bottle is exposed to ultraviolet irradiation equipment.
When ultraviolet rays were irradiated to give an integrated light intensity of 15 J/cm ² to 280 J/cm ² and the transmittance of the light was measured in the same way, the transmittance was 500 to
A selective decrease in transmittance occurred around the wavelength range of 550 nm, and the color gradually changed to purple. In this way, the glass bottle of the present invention can display the cumulative amount of ultraviolet light received as a change in color tone.

Example 2 SiO ₂ 71.5%, Al ₂ O ₃ 2.0%, Fe ₂ O ₃ 0.05%,
CaO10.5%, _Na2O10.5 %, _K2O5.0 %, _CeO2 0.20
%, V ₂ O ₅ 0.16% was melted and a glass bottle having a body wall thickness of 3 mm was formed by a conventional method. This glass bottle was irradiated with ultraviolet rays in the same manner as in Example 1, and the resulting change in light transmittance is shown in FIG. It can be seen that the glass bottle of this example also selectively absorbs light as the cumulative amount of ultraviolet light received increases, and is colored purple.

(Effects of the Invention) As explained above, the glass bottle of the present invention allows the contents to be clearly seen from the outside, and can be easily manufactured using conventional processes. Since the color changes to purple, consumers can easily know the possibility of the contents being deteriorated by ultraviolet rays during the distribution stage. Furthermore, since glass bottles collected from the market can be returned to their original color by reheating, they also have the advantage of being able to be used as recycled bottles. Therefore, the present invention greatly contributes to the development of industry as a glass bottle that can eliminate the problems of the conventional glass bottles and indicate the deterioration of the contents.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the amount of ultraviolet light received and the light transmittance characteristics in the first embodiment, and FIG. 2 is a graph showing the relationship between the amount of ultraviolet light received and the light transmittance characteristics in the second embodiment. be.

Claims (1)

[Claims] 1 0.01-1.0% _V2O5 and _0.05-0.5 % by weight
The content is made of soda lime glass containing CeO ₂ and is characterized in that only the surface layer gradually changes color to purple depending on the amount of ultraviolet irradiation, thereby informing the consumer of the possibility of deterioration of the content. A glass bottle displaying the alteration of.