JP2002347770A - Returnable glass bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a returnable glass bottle that does not cause any change in the appearance of the content therein after being coated with one layer of colorless transparent film, superior in alkaline cleaning resistance and damage resistance, withstanding repeated use, with the coating film being of minimal thickness and formed only on the necessary portion eliminating fear of coloring even when reused as glass cullet, and effectively reusable as is capable of being minutely crushed. SOLUTION: A glass bottle body 1 has its contact point on the outer surface treated with primer and further has a resin coating film 2 formed in a belt form made of a mixture of urethane resin having alkali resistance and styrene- butadiene rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a returnable glass which has a resin coating film formed on the outer surface, has excellent scratch resistance and alkali resistance, can be repeatedly used, and can be effectively reused as a glass cullet. It is about bottles.

[0002]

2. Description of the Related Art Conventionally, glass bottles have been widely coated with ceramics or resins for the purpose of coloring, or for preventing destruction or damage. For example, milk bottles, beer bottles, etc. are called returnable bottles and are used repeatedly and repeatedly. During repeated use, circumferential scratches (scuffs) occur at the contact points where adjacent bottles come into contact. ), Which may cause problems such as reduced strength and poor appearance quality. For this reason, a coating film of ceramics or resin is formed on the entire outer surface of the glass bottle,
Attempts have been made to solve the above problems.

[0003] More specifically, chemical vapor deposition those scratch resistance surface protective coating by applying the SnO _2, TiO ₂ or ZrO ₂ or the like ceramic film by chemical vapor deposition (CVD) and, these SnO
_2. There is a so-called dual coat in which a slip layer such as polyethylene is further coated on a ceramic film such as TiO ₂ or ZrO ₂ . In addition, polyurethane resin, polyethylene resin, acrylic resin, polypropylene resin, and other resin coatings are also performed. Returnable bottles such as milk bottles are undercoated with styrene butadiene rubber (SBR) and then polyurethane resin. Is also known that is overcoated with two layers.

However, a ceramic film such as SnO ₂ , TiO _2, or ZrO _{2 formed} by chemical vapor deposition (CVD) has a high refractive index and a large surface reflectivity. When applied to a colorless or transparent bottle, the transmittance of the glass is reduced and the transparency of the bottle may be impaired.Especially when milk is added, the contents appear dark and the product image deteriorates. Problems. In addition, SnO ₂ , TiO ₂ , ZrO ₂
In the case of a dual coat in which a slippery layer of polyethylene or the like is further coated on a ceramics film such as that described above, the effect on the appearance is small because the ceramics layer is as thin as 20 nm or less, but the alkali cleaning used in a returnable bottle ( For example, there is a problem that durability under conditions of immersion in a 4% NaOH solution at 80 ° C. for 5 hours is small), and the scratch resistance is not long-lasting. Further, in the case of a resin coating film such as a polyurethane resin, there is no sufficient adhesiveness, interface peeling or whitening of the film occurs at the end face of the coating film by alkali washing, and there is a problem in scratch resistance.

On the other hand, styrene butadiene rubber (SBR)
With a two-layer coating film of polyurethane and a polyurethane resin, there is no problem in appearance because a transparent resin having high alkali resistance is used, but the resin coating process is complicated because it is a two-layer coating (SBR coating → drying → urethane coating → drying) → curing), and since the coat film has a two-layer structure, if the positions of the SBR and the urethane at the end do not match, there is a problem that peeling from the end occurs. Furthermore, since it is a two-layer coating, the film thickness becomes as thick as 70 to 150 μm, which makes it difficult to grind it finely when reused as a glass cullet. There was also a problem such as there is.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and the resin coating film formed on the outer surface of the glass bottle comprises a single colorless and transparent coating film. It does not change the appearance of the glass, and is excellent in alkali washing resistance and scratch resistance so that it can be used repeatedly.The coating film has a minimum thickness and is formed only in the necessary parts. It is an object of the present invention to provide a returnable glass bottle which is free from coloring even when reused as a cullet, can be finely ground, and can be effectively reused.

[0007]

In order to solve the above-mentioned problems, a returnable glass bottle according to the present invention has a contact point on the outer surface of a glass bottle body in which styrene-butadiene rubber is mixed with urethane resin having alkali resistance. The resin coating film thus formed is formed in a belt shape.

The resin coating film formed in a belt shape is formed by applying a resin coating liquid in which a styrene-butadiene rubber is mixed in a weight ratio of 0.5% to 50% in a urethane resin liquid, and then heat-curing. The invention according to item 2, wherein the viscosity of the resin coating liquid is 5 to 80 mPa ·
The invention as claimed in claim 3 is defined as S, and the resin coating film having a thickness of 5 to 100 μm is defined as claim 4.
The invention according to claim 5, wherein the width of the resin coating film formed in a belt shape is 3 to 25 mm. Further, the invention is characterized in that a primer treatment layer is formed on the outer surface of the glass bottle main body, and a resin coating film is formed on the primer treatment layer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. The coating solution for glass bottles proposed in the present invention is a solution obtained by mixing styrene-butadiene rubber (SBR) conventionally used for the above-described two-layer coating and a polyurethane resin having alkali resistance into one solution. The styrene-butadiene rubber (SBR) and the polyurethane resin are preferably dispersed in water in terms of handling, but may be dissolved in an organic solvent. Styrene-butadiene rubber (SBR) is inferior in alkali resistance and scratch resistance, but has an effect of imparting appropriate elasticity to a film and adhesion to glass. Polyurethane resin has low adhesion to glass, There is an effect of imparting alkalinity and scratch resistance, and by mixing them, mutual defects can be compensated.

The amount of styrene-butadiene rubber (SBR) added to the polyurethane resin is 0.5 to 5 by weight.
0% is preferable, and if it is 0.5% or less, interfacial peeling during alkali cleaning cannot be suppressed, and if it is 50% or more, alkali resistance is reduced due to SBR that is weak to alkali, and peeling from the end occurs. More preferably 1.5 to 10%,
Most preferred is 3-10%.

The viscosity of the coating solution is 5 to 80 m
It is preferable to use it after adjusting to Pa · S. If it is 5 mPa · S or less, a constant film thickness after coating cannot be ensured, and the coating film does not have a sufficient damage suppressing effect. On the other hand, 80
If the pressure is higher than mPa · S, it is difficult to control the film thickness, and the film becomes unnecessarily thick. Further, more preferably, it is in the range of 10 to 35 mPa · S.

The resin coating film of the present invention preferably has a thickness after curing of 5 to 100 μm. If it is 5 μm or less, the scratch resistance is low, and the effect of suppressing the damage is not sufficient. On the other hand, if the thickness is 100 μm or more, a large amount of resin material is used, so that the material cost is increased, and the drying time becomes longer in the resin coating process. More preferably, it is in the range of 10 to 50 μm.

The curing temperature after coating the resin is preferably in the range of 150 to 250 ° C. 150 ° C
In the case below, the curing of the resin is insufficient, so that the alkali resistance and the scratch resistance cannot be sufficiently exhibited. If the temperature is higher than 250 ° C., the resin undergoes partial thermal denaturation, causing a problem of yellow discoloration, which also increases energy costs.

As the method of resin coating of the present invention, a known spray method, electrostatic coating method, brush coating method, brush coating method and the like can be used. In the present invention, the outer surface of the glass bottle main body is used. The brush-coating method or the brush-coating method is suitable for applying the belt-shaped coating only to the contact points of the above.

Before forming the resin coating film, a primer treatment layer may be formed on the outer surface of the glass bottle main body, and the resin coating film may be formed on the primer treatment layer. In this case, the resin coating film is more firmly adhered to the outer surface of the glass bottle via the primer treatment layer, which is preferable. Further, it is preferable that the primer treatment layer is formed in a belt shape only at the contact points on the outer surface of the glass bottle main body,
Of course, it may be formed on the entire surface. The type of the primer treatment liquid is not particularly limited, and for example, a mixture of alcohol, water, and a silane coupling agent can be used. The formation of the primer treatment layer may not be necessary depending on the type of the resin coating film.

Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a case where the present invention is applied to a milk bottle, wherein 1 is a glass bottle main body,
Reference numeral 2 denotes a strip-shaped resin coating film formed at the contact point. The contact point here is
When a plurality of bottles are conveyed and handled at the same time, it means a portion where adjacent bottles come into contact with each other, and is usually the maximum diameter portion at the shoulder portion and the lower portion of the trunk, depending on the bottle shape. In the present invention, only the contact point has a width of about 3 to 25 mm (preferably 5 to 25 mm).
7 mm), a resin coating film 1 in the form of a belt is formed at two locations, a shoulder portion and a lower portion of the trunk.

As described above, the one-component resin coating liquid obtained by mixing the styrene-butadiene rubber (SBR) with the urethane resin liquid becomes a colorless and transparent resin film after drying and curing. Is possible without impairing the coating. It is naturally possible to add a dye or a pigment as a coloring agent to the resin coating solution to perform color coating, or to add a finely pulverized ceramic or silica to give a frost-like appearance. And, by performing the resin coating of the present invention, it is possible to effectively suppress scratches generated when bottles rub against each other on a filling line or the like in a factory for filling contents.
Furthermore, by limiting the coating range in a strip shape to the contact point of the glass bottle main body, the cost of the resin material can be reduced, and when it is reused as a glass cullet, it is easy to grind it finely. It is suitable for recycling glass bottles without any risk of coloring the glass substrate by the coating film.

[0018]

Example 1 A solution was prepared by adding 0.12 g of a fluorine-based surfactant, 0.5 g of a silane coupling agent, and 20 g of an epoxy- and melamine-based curing agent as leveling agents to 100 g of a urethane resin liquid. In addition, the SBR is 0, 0.5, 1, 1.5, 2,.
SB to be 5, 5, 10, 30, 50, 100%
Mix the R latex liquid. When the liquid viscosity of the liquid thus prepared was large, the viscosity was appropriately adjusted by adding water. On the other hand, a bottle (standard I-300: manufactured by Ishizuka Glass Co., Ltd.) was prepared by priming the contact points on the outer surface with a liquid in which 10 parts of water and 2 parts of a silane coupling agent were mixed with 88 parts of denatured alcohol. Forming a strip-shaped resin coating film on the primer-treated layer;
After drying with warm air at a temperature of 4 ° C. for 4 minutes, a curing treatment was performed at 170 ° C. for 20 minutes. The coating film thus formed was coated with 1.2% Eclin 110 M (alkaline detergent:
Washed by immersion in 75 ° C liquid for 10 minutes,
A test in which a wound test using a line simulator manufactured by AGR Co., Ltd. for one minute was set as one trip, and a test in which 30 trips were repeatedly performed was performed. After 30 trips, the appearance of the coat film was visually observed, and the interface between the resin and the glass bottle was observed with a microscope to confirm the presence or absence of peeling. Table 1 shows the results.

[0019]

[Table 1]

As is clear from Table 1, it was confirmed that the one according to the embodiment in which the specific resin coating film was formed can suppress the generation of scratches even after repeated washing as used in a returnable bottle. did it. In addition, it was confirmed that by adding a small amount of SBR to the urethane resin, the state of separation at the interface was improved, and it was found that the interface was sufficiently practical.

Example 2 A solution was prepared by adding 5% SBR to a urethane solution prepared in the same manner as in Example 1. Water was appropriately added to this solution to adjust the viscosity, and a sample was prepared in which a band-shaped resin coating film having a different film thickness was formed at each contact point on the outer surface of the bottle by the same primer treatment as in Example 1. Table 2 shows the results of evaluation of this bottle by performing the same wound test as in Example 1.

[0022]

[Table 2]

[0023]

As is apparent from the above description, the resin-coated glass bottle of the present invention has excellent scratch resistance, can be used repeatedly, and has a minimum thickness as a strip-shaped coating film. Since it is formed only in the portion, there is no risk of coloring due to the coating film even when it is reused as glass cullet, and it can be finely ground and can be effectively reused. Further, there is an advantage that the amount of the coating liquid used can be reduced to 1/10 or less as compared with the conventional whole-surface coating, and the productivity can be greatly improved. Therefore, the present invention greatly contributes to the development of industry as a returnable glass bottle that has eliminated the conventional problems.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

[Explanation of symbols]

 1 glass bottle main body 2 belt-shaped resin coating film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3E062 AA09 AB02 AC06 JA04 JA08 JB23 JC02 JD08 4G059 AA04 AB01 AB05 AB11 AC16 FA16 FA17 FA30 FB05

Claims (6)

[Claims] 1. A returnable glass bottle wherein a resin coating film obtained by mixing styrene-butadiene rubber with urethane resin having alkali resistance is formed in a belt shape at a contact point on an outer surface of a glass bottle main body. 2. The resin coating film formed in a belt shape,
The returnable glass bottle according to claim 1, wherein a resin coating solution in which a styrene-butadiene rubber is mixed in a weight ratio of 0.5% to 50% in a urethane resin solution is applied and then cured by heating. 3. The returnable glass bottle according to claim 2, wherein the viscosity of the resin coating liquid formed in a belt shape is 5 to 80 mPa · S. 4. The returnable glass bottle according to claim 1, wherein the resin coating film formed in a belt shape has a thickness of 5 to 100 μm. 5. The returnable glass bottle according to claim 1, wherein the width of the strip-shaped resin coating film is 3 to 25 mm. 6. The returnable glass bottle according to claim 1, wherein a primer treatment layer is formed on an outer surface of the glass bottle main body, and a resin coating film is formed on the primer treatment layer.