JPH0476859B2 - - Google Patents

Description

[Detailed description of the invention]

The specific nonionic surfactant of the present invention is 0.01~
Contains 5wt% and has acetaldehyde content of
Concerning a carbonated beverage container made of polyester containing 20 ppm or less. More specifically, the present invention relates to a carbonated beverage container that can prevent the contents from blowing out when the polyester container filled with carbonated beverages is opened and troubles such as abnormally continuous bubbles occurring. BACKGROUND ART Polyester, particularly polyethylene terephthalate, has been widely used for fibers, films, sheets, and containers due to its excellent mechanical properties, workability, hygiene, and high-class aesthetics. Container uses include regular oil, salad oil,
It has come to be widely used both domestically and internationally, for seasonings such as sauces, for soft drinks such as juice, cola, and ramune, for draft beer, and for cosmetics. In addition to the excellent performance mentioned above, polyester for containers is lighter than glass, and has important characteristics such as pressure resistance and gas barrier properties for use in carbonated beverages, and is expected to grow even further in the future as an alternative to glass bottles. There is. However, even with such excellent polyester containers, there was one drawback that made them inferior to glass bottles. This is because polyester containers filled with carbonated beverages are generally filled under higher pressure than glass bottles, and the contents tend to blow out when the bottle is opened, or a series of abnormal air bubbles occur frequently. This has been a problem that must be overcome in the industry, as it stains the surface of the skin and causes discomfort. As a result of intensive study to solve this problem, the present inventors found the following conclusion and arrived at the present invention. First of all, when polyester containers are used as carbonated beverage containers, they are more likely to blow out when opened and to generate continuous abnormal air bubbles than glass bottles. In addition to being easily compatible with water, it requires a washing process before filling the carbonated beverage. On the other hand, polyester containers are organic and have little compatibility with the contents (mainly water), are inherently hygienic, and are actually heated and sterilized during container molding, so cleaning is not necessary. Since there is no need for cleaning before filling, as with glass bottles, it is thought that these points conversely make the compatibility with the contents (hydrophilicity) insufficient. It has been found that this causes bubble generation nuclei in carbonated drinks that are filled in a supersaturated state, which causes blowing out when the bottle is opened and abnormal continuous generation of bubbles. The present inventors have arrived at the present invention as a result of studies to solve the above-mentioned problems based on the above reasoning. In other words, it maintains the transparency and no effect on taste that originally exist for carbonated beverage containers,
In addition, a method has been discovered for providing a carbonated beverage container that does not cause any abnormal blow-out or bubble formation when the cap is opened. The gist of the present invention is that the HLB value is 8 to
Contains 0.01-5wt% of 20 nonionic surfactants,
A carbonated beverage container made of polyester with an acetaldehyde content of 20 ppm or less. The present invention will be explained step by step below. In the present invention, polyester refers to polyethylene terephthalate and polyester containing this as a main component, which accounts for 15 mol% of the total acid component.
In the following amounts, dicarboxylic acids such as phthalic acid, isophthalic acid, hexahydrophthalic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid, polycarboxylic acids such as trimellitic acid, pyromellitic acid,
Alternatively, oxybenzoic acid such as p-oxybenzoic acid can be used as the acid component. In addition, in an amount of 10 mol% or less of the total alcohol component,
Glycols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, trimethylolpropane, It is also possible to use polyhydric alcohols such as triethylolpropane and pentaerythritol. The method for producing polyester is a so-called two-step reaction in which a commonly known transesterification reaction or direct esterification reaction is carried out to obtain a polyester oligomer, followed by a polycondensation reaction. In this case, as the transesterification catalyst, one or more types of known compounds such as calcium compounds, manganese compounds, zinc compounds, and lithium compounds can be used, but manganese compounds are preferred from the viewpoint of transparency. Furthermore, one or more phosphorus compounds may be added as a stabilizer after the transesterification reaction or esterification reaction is substantially completed. As the polymerization catalyst, one or more of known antimony compounds, germanium compounds, titanium compounds, cobalt compounds, etc. can be used, but antimony compounds, germanium compounds, and titanium compounds are preferably used, and germanium compounds and titanium compounds are more preferable. is used. Additionally, additives such as color tone improvers and colorants may be included as necessary during the production of polyester. The nonionic surfactant used in the present invention is
Calculated before added to polyester
It is necessary to satisfy the HLB value in the range of 8 to 20. The HLB value referred to in the present invention is the HLB value invented by Mr. Griffin (WCGriffin, J.Soc.Cosm.
Chem, Vol. 1, p. 311 (1949)) and is expressed by the following formula (1). HLB value = weight of hydrophilic group / weight of hydrophobic group + weight of hydrophilic group x 1
00/5... (1) As a nonionic surfactant with an HLB value in the range of 8 to 20, the general formula (In the formula, R ¹ and R ² represent a hydrogen atom, an alkyl group, or an alkylphenyl group, R ³ and R ⁴ represent a hydrogen atom or an alkyl group, and n ₁ and n ₂ are determined by the HLB value. The HLB value is 8 to 8 and is selected from polyalkylene glycol derivatives and/or ethylene oxide adducts of fatty acid monoesters, diesters, and triesters of sorbitan shown in 20 nonionic surfactants are preferred. Specifically, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polyoxyethylene-polyoxypropylene block polymer, polyalkylene glycols such as polyethylene glycol laurate monoester, polyethylene glycol stearate monoester, and polyethylene glycol oleate monoester are used. Glycol monoester, polyalkylene glycol diester such as polyethylene glycol laurate diester, polyethylene glycol stearate diester, polyethylene glycol oleate diester, alkylphenol polyoxyalkylene such as nonylphenol polyoxyethylene, dodecylphenol polyoxyethylene, lauryl alcohol polyester Higher alcohol polyoxyalkylene such as oxyethylene, oleyl alcohol polyoxyethylene, Matsukou alcohol polyoxyethylene, sorbitan lauric acid monoester polyoxyethylene, sorbitan palmitic acid monoester polyoxyethylene, sorbitan stearic acid monoester polyoxyethylene, Examples include polyhydric alcohol ester polyalkylene such as sorbitan oleate monoester polyoxyethylene and sorbitan oleate triester polyoxyethylene. The content of the above nonionic surfactant in the polyester is 0.01 to 5 wt%, preferably 0.01 to 5 wt%.
3wt%, more preferably 0.01 to 1wt%.
If the amount is less than 0.01 wt%, the effect of the present invention is insufficient. Moreover, if it exceeds 5 wt%, it is not preferable because it causes a decrease in the thermal stability of the polyester itself and a decrease in physical properties due to a decrease in molecular weight. The nonionic surfactant used in the present invention
The HLB value must be in the range of 8 to 20,
More preferably it is in the range of 10-16. HLB value 8
If it is less than that, when it is made into a molded product, its compatibility with water is insufficient, and the effects of the present invention cannot be achieved. There are no particular restrictions on the timing or order of blending the nonionic surfactant into the polyester. It may be added during the polycondensation, or may be blended in the molten state after the completion of the polycondensation, in the pellet state, or at a stage before molding. The polyester containing a nonionic surfactant in the present invention has a low acetaldehyde content.
It needs to be 20ppm or less. Exceeding 20 ppm of acetaldehyde is subject to the present invention. It is not preferred as a composition for carbonated beverage containers because it impairs the taste of the contents. The content of acetaldehyde in polyester can be generally reduced by producing the polyester by the method described above and then subjecting it to solid phase polymerization. The solid phase polymerization treatment is usually carried out at a temperature of 120°C to just below the melting point of polyester for several tens of hours or less, but in order to achieve an acetaldehyde content of 20 ppm or less, it is carried out at a temperature of 195°C to 230°C for 5 hours or less. It is preferable to do it for more than an hour. Further, the intrinsic viscosity of the polyester in the present invention needs to be 0.60 or more, preferably 0.70 to 0.90. If the intrinsic viscosity is less than 0.60, not only the transparency of the container will be insufficient, but also the mechanical properties will be impaired. A carbonated beverage container can be obtained by biaxial stretching blowing. A method for obtaining a biaxially stretched blown container is to produce a preform, which is a preform, by injection molding, and then heat stretch blow molding to make a biaxially stretched blown container, or to produce a pipe-shaped intermediate material by extrusion molding. After molding, the tip is welded to form the bottom of the container, the top (rear end) is pressed and deformed to form the mouth, and this is biaxially stretched and blown. Even if it is heat-set by a known method, the effects of the present invention will not be lost. As a specific method for manufacturing these biaxially stretched blow containers, conventional methods and conditions can be used as appropriate. As for the biaxial stretching ratio, it is desirable that the volume ratio of the preform (intermediate) before biaxial stretching to the container after biaxial stretching blowing is at least 3 times, preferably 5 times or more. The present invention will be explained below with reference to Examples. In addition, "parts" in the examples represent "parts by weight",
Measurements of intrinsic viscosity, acetaldehyde and transparency are as follows. <Intrinsic viscosity> Value measured at 30°C using a mixed solvent with a weight ratio of phenol and tetrachloroethane of 1:1 at a concentration of 1gr/dl. <Acetaldehyde> 5gr polyester made into chips of several meters/m square
Add 10 ml of distilled water per sample, hold at 160°C for 2 hours, and then rapidly cool. The acetaldehyde extracted in the distilled water is determined by gas chromatography and calculated as the concentration in the polyester (unit: ppm). <Transparency> Nippon Denshoku Industries Co., Ltd. haze meter (NDH-
Haze (cloudiness) value measured using 20D model).
(Unit: %) Example 1 <Manufacture of polyester composition> Intrinsic viscosity 0.60, acetaldehyde content
For 100 parts of 118ppm polyester chips, apply Liponox NCI (trade name of Lion Oil Co., Ltd.) (HLB=
12.9 nonylphenyl polyethylene oxide)
After mixing 0.5 parts in a blender, under _N2 flow
140℃-2 hours, 160℃-4 hours, then 200℃-
The temperature was raised stepwise for 18 hours, and solid phase polymerization was performed.
A polyester composition with an intrinsic viscosity of 0.81 and acetaldehyde reduced to 3.8 ppm was obtained. <Manufacture of biaxially stretched blow container> The obtained polyester composition was
280℃ setting cycle using 60B injection molding machine
A threaded preform with a thickness of 4mm, total length of 150mm, and diameter of 28mmφ is molded in 65 seconds, and then with a blow machine,
A biaxially stretched blow container with a capacity of 1 was molded at a blowing pressure of 25 kg/cm ³ . When the body of this container was cut out and the extreme viscosity and haze (cloudiness) were measured, the intrinsic viscosity was 0.79.
The transparency was good at 0.4%. The content of acetaldehyde was 10.5 ppm, which was a fully satisfactory value. <Evaluation of blowing with carbonated drinks> The obtained biaxially stretched blow container with a capacity of 1
Fill 950 ml of commercially available carbonated beverage with 3.3 gas volume at 0℃, tightly stopper it, stir thoroughly, store it in a room at 23℃ and 50% relative humidity all day and night, and then open the bottle.No bubbling was observed after 1 hour. The content loss was 5gr. Further, no abnormal bubble formation from the container wall was observed. Comparative Example 1 A biaxially stretched blow container having a capacity of 1 was obtained in exactly the same manner as in Example 1 except that no nonionic surfactant was added. The haze of this container was 1.0%, which was on par with conventional products. In addition, as a result of filling carbonated drinks and testing in exactly the same manner as in Example 1, a so-called blow-out phenomenon occurred, and the loss of content after 1 hour was 39gr, and even after that, abnormality of air bubbles coming from the container wall and bottom was observed. The outbreak occurred continuously. Examples 2 and 3 and Comparative Example 2 An experiment was conducted in the same manner as in Example 1, except that the nonionic surfactant added was changed, and the results shown in Table 1 were obtained. Examples 4 to 7 and Comparative Examples 3 and 4 To 100 parts of polyester chips with an intrinsic viscosity of 0.74 (Nippon Unipet Co., Ltd., RT-543C), 0.3 parts each of the nonionic surfactants shown in Table 2 was added to a blender. After mixing at 140° C. for 6 hours under N ₂ flow. Similar experiments were conducted using the obtained composition in the same manner as in Example 1, using it as a biaxially stretched blow container with a capacity of 1. The results are shown in Table-2. As is clear from Tables 1 and 2, it can be seen that the method of the present invention is effective against the abnormal generation and blow-out of bubbles in carbonated beverage containers.

[Table] *1 Polyoxyethylene alkyl ether type nonionic surfactant *2 Nonylphenyl polyethylene oxide type nonionic surfactant

【table】

Claims (1)

[Claims] 1 Consisting of a polyester having an intrinsic viscosity of 0.60 or more and containing ethylene terephthalate as a main repeating unit, the polyester contains 0.01 to 5 wt% of a nonionic surfactant with an HLB value of 8 to 20, and the polyester contains Contains acetaldehyde
A container for carbonated beverages, characterized in that the content is 20 ppm or less as measured by a water extraction method at 160°C for 2 hours.