JPH04238017A - Manufacture of saturated polyester bottle - Google Patents

Abstract

PURPOSE:To effectively prevent crack from developing at the bottom part of the bottle concerned by a method wherein only the bottom part of the bottle is subjected to heat setting treatment after the bottle is formed by blow- stretching saturated polyester preform. CONSTITUTION:The saturated polyester bottle consists of a stopper part 2, an upper shoulder part 3, a cylinder part 4 and a bottom part 5. In order to manufacture the bottle, firstly, preform is formed out of resin by means of, for example, injection molding, extrusion molding or the like. Next, only the bottom part of the bottle is subjected to heat setting treatment under the mold temperature of 140-20 deg.C for 10-50sec. By applying heat setting treatment only to the bottom part of tire bottle as mentioned above, the degree of crystallization of the surface layer part, the crystallization at which is insufficient, of the bottom part of the bottle becomes larger, resulting in obtaining a bottle excellent in stress crack resistance. As the saturated polyester resin, polyethylene terephthalate resin, polyethylene naphthalate resin, copolymer polyester resin or the like is used.

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a saturated polyester bottle, and more particularly to a method for manufacturing a saturated polyester bottle with excellent stress crack resistance. [Technical Background of the Invention] In recent years, various plastic materials have been used as materials for bottles for carbonated drinks such as juice and cola, and among these plastic materials, saturated polyesters such as polyethylene terephthalate are transparent It is widely used because of its excellent gas barrier properties, heat resistance, and mechanical strength. [0003] Such a saturated polyester bottle is
If it is the round bottom type shown in Figure 1 (B), there will be almost no problems such as cracks occurring at the bottom.
) In the case of free-standing bottles such as the petaloid bottles shown in (), greater stress is applied to the bottom than in the case of round-bottomed bottles, so there is a risk of cracks occurring at the bottom during the distribution stage from filling to sales. Ta. [0004] The reason why such cracks occur at the bottom of free-standing bottles is that the shape of the bottom of free-standing bottles is more complicated than that of round-bottomed bottles, and there are parts that are difficult to stretch.
This is thought to be because residual stress during molding tends to remain around the boundary between the stretched part and the unstretched part, and the strength of the material decreases mainly due to external influences, and the residual stress is released. Temperature, moisture, chemicals, solvents, etc. can be considered as such external factors. [0005] The inventors of the present invention have conducted extensive studies based on the above knowledge, and have found that in order to prevent the occurrence of such cracks, it is necessary to improve the crystallinity of the unstretched amorphous portion. The present invention has been completed based on this discovery. OBJECT OF THE INVENTION The present invention aims to solve the problems associated with the prior art as described above. It is an object of the present invention to provide a method for manufacturing a saturated polyester bottle that does not cause cracks to occur at the bottom due to various factors. Summary of the Invention The method for manufacturing a saturated polyester bottle according to the present invention includes stretching and blowing a saturated polyester preform to form a bottle, and then heat-setting only the bottom of the bottle. It is characterized by DETAILED DESCRIPTION OF THE INVENTION The method for manufacturing a saturated polyester bottle according to the present invention will be explained below, but first the saturated polyester resin used in the present invention will be explained. The saturated polyester resins used in the saturated polyester bottle according to the present invention include polyethylene terephthalate resin, polyethylene naphthalate resin, and the following copolymerized polyester resins (1) to (
7), etc. Each resin will be explained in more detail below. Polyethylene terephthalate resin The polyethylene terephthalate resin used in the saturated polyester bottle according to the present invention is produced using terephthalic acid and ethylene glycol as raw materials,
This polyethylene terephthalate resin may be copolymerized with 20 mol% or less of other dicarboxylic acids and/or other dihydroxy compounds. In addition to terephthalic acid, specific dicarboxylic acids used in copolymerization include phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyldicarboxylic acid,
Examples include aromatic dicarboxylic acids such as diphenoxyethanedicarboxylic acid; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and decanedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. In addition to ethylene glycol, dihydroxy compounds used in copolymerization include aliphatic glycols such as trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, and dodecamethylene glycol; cyclohexane; Alicyclic glycols such as dimethanol; bisphenols; hydroquinone, 2,
Examples include aromatic diols such as 2-bis(4-β-hydroxyethoxyphenyl)propane. [0013] Such a polyethylene terephthalate resin can be made into a substantially linear polyester by ethylene terephthalate component units alone or by randomly arranging the ethylene terephthalate component units and dioxyethylene terephthalate component units to form ester bonds. is forming. The fact that the polyethylene terephthalate resin is substantially linear is confirmed by dissolving the polyethylene terephthalate resin in o-chlorophenol. [0014] Such polyethylene terephthalate resin has an intrinsic viscosity [η] (25
It is desirable that the value (measured at °C) is usually 0.6 to 1.5 dl/g, preferably 0.7 to 1.2 dl/g. In addition, the melting point is usually 210°C to 265°C, preferably 210°C to 265°C.
It is desirable that the temperature is 20 to 260°C, and the glass transition temperature is usually 50 to 120°C, preferably 60 to 100°C. Polyethylene naphthalate resin The polyethylene naphthalate resin used in the saturated polyester bottle according to the present invention is an ethylene naphthalate resin derived from 2,6-naphthalene dicarboxylic acid and ethylene glycol.
It is desirable to contain 2,6-naphthalate units in an amount of 60 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, but 40 mol% or more of structural units other than ethylene-2,6-naphthalate. It may be contained in an amount less than mol%. [0016] Constituent units other than ethylene-2,6-naphthalate include terephthalic acid, isophthalic acid, 2,7
-naphthalene dicarboxylic acid, 2,5-naphthalene dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, 4,4
Aromatic dicarboxylic acids such as '-diphenyl ether dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, dibromoterephthalic acid; [0017] Adipic acid, azelaic acid, sebacic acid,
Aliphatic dicarboxylic acid such as decanedicarboxylic acid; 1,4
-Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, cyclopropanedicarboxylic acid, hexahydroterephthalic acid; glycolic acid, p-hydroxybenzoic acid, p-
Hydroxycarboxylic acids such as hydroxyethoxybenzoic acid, propylene glycol, trimethylene glycol, diethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, p-xylene glycol, 1 , 4-cyclohexanedimethanol, bisphenol A, p,p-diphenoxysulfone, 1,4-bis(β-hydroxyethoxy)benzene, 2,2-bis(p-β-hydroxyethoxyphenol)propane, polyalkylene glycol , p-phenylenebis(dimethylsiloxane), glycerin, and the like. The polyethylene naphthalate resin used in the present invention also contains a small amount, for example, 2 mol % or less, of a structural unit derived from a polyfunctional compound such as trimesic acid, trimethylolethane, trimethylolpropane, trimethylolmethane, or pentaerythritol. It may be included in an amount of Furthermore, the polyethylene naphthalate resin used in the present invention contains a small amount, for example 2 moles, of a constituent unit derived from a monofunctional compound such as benzoylbenzoic acid, diphenylsulfone monocarboxylic acid, stearic acid, methoxypolyethylene glycol, or phenoxypolyethylene glycol. % or less. [0021] Such polyethylene naphthalate resins are substantially linear, which is confirmed by their dissolution in o-chlorophenol. The intrinsic viscosity [η] of polyethylene naphthalate resin measured in o-chlorophenol at 25°C is:
0.2-1.1dl/g, preferably 0.3-0.9d
l/g, particularly preferably in the range of 0.4 to 0.8 dl/g. The intrinsic viscosity [η] of the polyethylene naphthalate resin is measured by the following method. That is, polyethylene naphthalate resin was dissolved in o-chlorophenol at a concentration of 1 g/100 ml, and the solution viscosity was measured using an Ubbelohde capillary viscometer at 25°C.
After that, o-chlorophenol was gradually added, the solution viscosity on the low concentration side was measured, and the concentration was increased to 0%, and the intrinsic viscosity (
[η]). [0024] Furthermore, the crystallization temperature (Tc) of polyethylene naphthalate resin when heated at a rate of 10°C/min using a differential scanning calorimeter (DSC) is usually 150°C or higher, preferably 160-230°C, more preferably 1
It is desirable that the temperature is in the range of 70 to 220°C. The elevated temperature crystallization temperature (Tc) of polyethylene naphthalate resin is measured by the following method. That is, using a PerkinElmer Model DSC-2 running differential calorimeter, a temperature of about 5 mmHg was measured at about 140°C under a pressure of about 5 mmHg.
A sample of about 10 mg of a thin piece taken from the center of a polyethylene naphthalate resin chip that has been dried for more than an hour is sealed in an aluminum pan for liquid under a nitrogen atmosphere and measured. The measurement conditions are: First, the temperature is rapidly raised from room temperature, melted and held at 290°C for 10 minutes, then rapidly cooled to room temperature, and then the temperature is the peak temperature of the exothermic peak detected when the temperature is raised at a rate of 10°C/min. seek. [0026]
Copolymerized polyester resin (1) The copolymerized polyester resin (1) used in the saturated polyester bottle according to the present invention contains a dicarboxylic acid constituent unit including a terephthalic acid component unit and an isophthalic acid component unit, and an ethylene glycol component unit. It is formed from dihydroxy compound structural units. The dicarboxylic acid constituent units constituting this copolymerized polyester resin (1) include terephthalic acid component units in an amount of 85 to 99.5 mol%, preferably 90 to 99.5 mol%, and isophthalic acid component units. Component unit is 0.5-15
Desirably, it is present in an amount of mol %, preferably 0.5 to 10 mol %. Copolymerized polyester resin (1) according to the present invention
), in addition to the above-mentioned terephthalic acid and isophthalic acid, the dicarboxylic acid component is used within a range that does not impair the properties of the resulting copolyester resin (1), such as 1
Other dicarboxylic acids can also be used in amounts up to mole percent. Examples of such dicarboxylic acids include phthalic acid, 2-methylterephthalic acid, and 2,6-naphthalene dicarboxylic acid. In addition, in the copolyester resin (1) according to the present invention, in addition to ethylene glycol as described above, the dihydroxy compound may be added in an amount within a range that does not impair the properties of the resulting copolyester resin (1), for example, 1 mol% or less. Other dihydroxy compounds can also be used. [0030] Such dihydroxy compounds include:
1,3-propanediol, 1,4-butanediol,
Neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, 1,3-bis(2-hydroxyethoxy)benzene, 1,4-bis(2-hydroxyethoxy)benzene, 2,2-bis(4-β-hydroxyethoxyphenyl) ) propane, bis(4-β-hydroxyethoxyphenyl)sulfone, and other dihydroxy compounds having 3 to 15 carbon atoms. Copolymerized polyester resin (2) The copolymerized polyester resin (2) used in the saturated polyester bottle according to the present invention is a dicarboxylic acid constituent unit containing a terephthalic acid component unit and a 2,6-naphthalene dicarboxylic acid component unit. and a dihydroxy compound structural unit containing an ethylene glycol component unit. The dicarboxylic acid constituent units constituting this copolymerized polyester resin (2) include terephthalic acid component units in an amount of 80 to 99.5 mol%, preferably 90 to 99.5 mol%, and 2, It is desirable that the 6-naphthalene dicarboxylic acid component units are present in an amount of 0.5 to 20 mol%, preferably 0.5 to 10 mol%. Copolymerized polyester resin (2) according to the present invention
), in addition to the above-mentioned terephthalic acid and 2,6-naphthalene dicarboxylic acid, other dicarboxylic acid components are used in an amount that does not impair the properties of the resulting copolyester resin (2), for example, 1 mol% or less. Dicarboxylic acids can also be used. Examples of such dicarboxylic acids include isophthalic acid, phthalic acid, and 2-methylterephthalic acid. In addition, in the copolymerized polyester resin (2) according to the present invention, in addition to the above-mentioned ethylene glycol, the dihydroxy compound may be added within a range that does not impair the properties of the resulting copolymerized polyester resin (2), for example, 1
Other dihydroxy compounds can also be used in amounts up to mole percent. [0035] Such dihydroxy compounds include:
1,3-propanediol, 1,4-butanediol,
Neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, 1,3-bis(2-hydroxyethoxy)benzene, 1,4-bis(2-hydroxyethoxy)benzene, 2,2-bis(4-β-hydroxyethoxyphenyl) ) propane, bis(4-β-hydroxyethoxyphenyl)sulfone, and other dihydroxy compounds having 3 to 15 carbon atoms. Copolymerized polyester resin (3) The copolymerized polyester resin (3) used in the saturated polyester bottle according to the present invention contains a dicarboxylic acid constituent unit containing a terephthalic acid component unit and an adipic acid component unit,
It is formed from a dihydroxy compound structural unit containing an ethylene glycol component unit. The dicarboxylic acid constituent units constituting this copolymerized polyester resin (3) include terephthalic acid component units in an amount of 85 to 99.5 mol%, preferably 90 to 99.5 mol%, and adipic acid component units in an amount of 85 to 99.5 mol%, preferably 90 to 99.5 mol%. It is desirable that the component units are present in an amount of 0.5 to 15 mol%, preferably 0.5 to 10 mol%. Copolymerized polyester resin (3) according to the present invention
), other dicarboxylic acids may be used as the dicarboxylic acid component in addition to the above-mentioned terephthalic acid and adipic acid in an amount that does not impair the properties of the resulting copolyester resin (3), for example, in an amount of 1 mol% or less. You can also do it. Examples of such dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, 2,6-
Examples include naphthalene dicarboxylic acid. Moreover, in the copolymerized polyester resin (3) according to the present invention,
In addition to ethylene glycol as a dihydroxy compound,
Other dihydroxy compounds can also be used in an amount that does not impair the properties of the resulting copolyester resin (3), for example, in an amount of 1 mol % or less. [0040] Such dihydroxy compounds include:
1,3-propanediol, 1,4-butanediol,
Neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, 1,3-bis(2-hydroxyethoxy)benzene, 1,4-bis(2-hydroxyethoxy)benzene, 2,2-bis(4-β-hydroxyethoxyphenyl) ) propane, bis(4-β-hydroxyethoxyphenyl)sulfone, and other dihydroxy compounds having 3 to 15 carbon atoms. Copolymerized polyester resin (4) The copolymerized polyester resin (4) used in the saturated polyester bottle according to the present invention contains dicarboxylic acid constituent units including terephthalic acid constituent units, ethylene glycol constituent units, and diethylene glycol constituent units. It is formed from a dihydroxy compound constituent unit containing. The dihydroxy compound constituent units constituting this copolymerized polyester resin (4) contain 93 to 98 mol%, preferably 95 to 98 mol% of ethylene glycol component units.
It is desirable that the diethylene glycol component units are present in an amount of 2 to 7 mol %, preferably 2 to 5 mol %. Copolymerized polyester resin (4) according to the present invention
), other dicarboxylic acids may be used as the dicarboxylic acid component in addition to the above-mentioned terephthalic acid in an amount that does not impair the properties of the resulting copolyester resin (4), for example, in an amount of 1 mol % or less. Examples of such dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, 2,6-
Examples include naphthalene dicarboxylic acid. Moreover, in the copolymerized polyester resin (4) according to the present invention,
In addition to the above-mentioned ethylene glycol and diethylene glycol, other dihydroxy compounds can also be used in an amount that does not impair the properties of the resulting copolyester resin (4), for example, in an amount of 1 mol% or less. [0045] Such dihydroxy compounds include:
1,3-propanediol, 1,4-butanediol,
Neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, 1,3-bis(2-hydroxyethoxy)benzene, 1,4-bis(2-hydroxyethoxy)benzene, 2,2-bis(4-β-hydroxyethoxyphenyl) ) Dihydroxy compounds having 3 to 15 carbon atoms such as propane and bis(4-β-hydroxyethoxyphenyl)sulfone are used.
Copolymerized polyester resin (5) The copolymerized polyester resin (5) used in the saturated polyester bottle according to the present invention is:
a dicarboxylic acid constituent unit containing a terephthalic acid constituent unit;
It is formed from a dihydroxy compound structural unit containing an ethylene glycol component unit and a neopentyl glycol component unit. The dihydroxy compound constituent units constituting this copolymerized polyester resin (5) contain 85 to 99.5 mol% of ethylene glycol component units, preferably 90 to 99.5 mol%.
In an amount of 99.5 mol %, the neopentyl glycol component unit is also 0.5 to 15 mol %, preferably 0.5 to 1
Preferably, it is present in an amount of 0 mol%. Copolymerized polyester resin (5) according to the present invention
), other dicarboxylic acids can be used as the dicarboxylic acid component in addition to the above-mentioned terephthalic acid in an amount that does not impair the properties of the obtained copolyester resin (5), for example, in an amount of 1 mol % or less. Examples of such dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, 2,6-
Examples include naphthalene dicarboxylic acid. Moreover, in the copolymerized polyester resin (5) according to the present invention,
In addition to the above-mentioned ethylene glycol and neopentyl glycol as the dihydroxy compound, a range that does not impair the properties of the resulting copolyester resin (5),
Other dihydroxy compounds can also be used, for example in amounts up to 1 mole percent. [0050] Such dihydroxy compounds include:
1,3-propanediol, 1,4-butanediol,
Cyclohexanediol, cyclohexanedimethanol, 1,3-bis(2-hydroxyethoxy)benzene,
1,4-bis(2-hydroxyethoxy)benzene, 2
, 2-bis(4-β-hydroxyethoxyphenyl)propane, bis(4-β-hydroxyethoxyphenyl)
Dihydroxy compounds having 3 to 15 carbon atoms such as sulfone can be mentioned. Copolymerized polyester resin (6) The copolymerized polyester resin (6) used in the saturated polyester bottle according to the present invention contains a dicarboxylic acid constituent unit containing a terephthalic acid component unit, an ethylene glycol component unit, and cyclohexanedimethanol. It is formed from a dihydroxy compound structural unit containing a component unit. The dihydroxy compound constituent units constituting this copolymerized polyester resin (6) contain 85 to 99.5 mol% of ethylene glycol component units, preferably 90 to 99.5 mol%.
In an amount of 99.5 mol %, the cyclohexanedimethanol component unit is also 0.5 to 15 mol %, preferably 0.5 mol %.
Desirably, it is present in an amount of ~10 mole %. Copolymerized polyester resin (6) according to the present invention
), other dicarboxylic acids may be used as the dicarboxylic acid component in addition to the above-mentioned terephthalic acid in an amount that does not impair the properties of the obtained copolyester resin (6), for example, in an amount of 1 mol % or less. Examples of such dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, 2,6-
Examples include naphthalene dicarboxylic acid. Moreover, in the copolymerized polyester resin (6) according to the present invention,
In addition to the above-mentioned ethylene glycol and cyclohexanedimethanol as the dihydroxy compound, other dihydroxy compounds can also be used in an amount that does not impair the properties of the resulting copolyester resin (6), for example, 1 mol% or less. [0055] Such dihydroxy compounds include:
1,3-propanediol, 1,4-butanediol,
Cyclohexanediol, cyclohexanedimethanol, 1,3-bis(2-hydroxyethoxy)benzene,
1,4-bis(2-hydroxyethoxy)benzene, 2
, 2-bis(4-β-hydroxyethoxyphenyl)propane, bis(4-β-hydroxyethoxyphenyl)
Dihydroxy compounds having 3 to 15 carbon atoms such as sulfone are used. Copolymerized polyester resin (7) The copolymerized polyester resin (7) used in the saturated polyester bottle according to the present invention contains a dicarboxylic acid constituent unit,
It is formed from a dihydroxy compound structural unit and a polyfunctional hydroxy compound structural unit having at least three hydroxy groups. The dicarboxylic acid constituent units constituting this copolymerized polyester resin (7) include isophthalic acid component units in an amount of 20 to 100 mol%, preferably 50 to 98 mol%, and terephthalic acid component units in an amount of 0 to 100 mol%. Desirably it is present in an amount of ~80 mol%, preferably 0.5-50 mol%. [0058] In addition, the dihydroxy compound constituent units include dihydroxyethoxy resol component units in an amount of 5 to 90 mol%.
, preferably in an amount of 10 to 85 mol%, and ethylene glycol component units in an amount of 10 to 95 mol%, preferably 1
Preferably, it is present in an amount of 5 to 90 mol%. [0059] This copolymerized polyester resin (7) contains:
A polyfunctional hydroxy compound unit having at least three hydroxy groups is present. This polyfunctional hydroxy compound structural unit is 0.05 to 1.0 mol part, preferably 0.1 mol part per 100 mol parts of dicarboxylic acid component units.
Preferably, it is present in an amount of ~0.5 mole part. Such polyfunctional hydroxy compound structural units are derived from compounds such as trimethylolmethane, trimethylolethane, and trimethylolpropane, among which trimethylolpropane is preferred. Copolymerized polyester resin (7) according to the present invention
), in addition to the above-mentioned isophthalic acid and terephthalic acid as the dicarboxylic acid component, a range that does not impair the properties of the resulting copolyester resin (7), such as 1
Other dicarboxylic acids can also be used in amounts up to mole percent. Examples of such dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, 2,6-
Examples include naphthalene dicarboxylic acid. Moreover, in the copolymerized polyester resin (7) according to the present invention,
In addition to dihydroxyethoxyresol and ethylene glycol as described above, other dihydroxy compounds can also be used in an amount that does not impair the properties of the resulting copolyester resin (7), for example, 1 mol% or less. [0063] Such dihydroxy compounds include:
1,3-propanediol, 1,4-butanediol,
Neopentyl glycol, cyclohexanediol, cyclohexanedimethanol, 1,3-bis(2-hydroxyethoxy)benzene, 1,4-bis(2-hydroxyethoxy)benzene, 2,2-bis(4-β-hydroxyethoxyphenyl) ) Dihydroxy compounds having 3 to 15 carbon atoms such as propane and bis(4-β-hydroxyethoxyphenyl)sulfone are used. Note that the above copolymerized polyester resin (1
The molecular weights of ) to (7) are not particularly limited as long as they are within a range that allows various molded articles, such as bottles, to be produced from the resulting saturated polyester resin composition, but usually copolymerized polyester resins in an o-chlorophenol solvent are used. It is desirable that the intrinsic viscosity [η] of is in the range of 0.5 dl/g to 1.5 dl/g or more, preferably 0.6 to 1.2 dl/g. [0065] Each of the resins constituting the saturated polyester bottle as described above can be manufactured by conventionally known manufacturing methods. In addition, various compounding agents such as cross-linking agents, heat-resistant stabilizers, weather-resistant stabilizers, antistatic agents, lubricants, mold release agents, inorganic fillers, pigment dispersants, pigments, or dyes are added to each of the above resins. It can be added within a range that does not impair the purpose of the present invention. Next, a method for manufacturing a saturated polyester bottle according to the present invention will be specifically explained. The saturated polyester bottle according to the present invention includes a spout 2, an upper shoulder 3, a body 4, and a bottom 5, as illustrated in FIG. 1(A). [0067] To manufacture such a bottle, first,
A preform is manufactured from the resin as described above, and the preform can be manufactured by a conventionally known method such as injection molding or extrusion molding. The heating temperature of the saturated polyester for forming the preform is preferably 90 to 110°C when the saturated polyester resin is polyethylene terephthalate resin, for example. [0068] Heat setting treatment conditions vary greatly depending on the type of polyester resin used, but the case of polyethylene terephthalate resin will be described below. The molded preform is heated to the appropriate temperature for stretching, and stretch blow molded in a mold. [0069] Next, only the bottom of the bottle was heated to 140 to 200
at a mold temperature of 10-50 seconds, preferably 10-3
Heat set treatment is performed for 0 seconds. By applying the heat setting treatment only to the bottom of the bottle in this way, the degree of crystallinity of the surface layer of the bottom of the bottle, which is insufficiently crystallized, increases, and a bottle with excellent stress crack resistance can be obtained. Note that the density of the polyethylene terephthalate resin that forms the bottle varies depending on the degree of stretching even in the bottom part, and if no heat setting is performed, the density will be 1.
It is about 335 to 1.370 g/cm3, but when heat set it is 1.370 to 1.385 g depending on the temperature.
It is preferable to control it to about /cm3. [0071] In the method for manufacturing a saturated polyester bottle according to the present invention, only the bottom of the bottle is heat-set, so the degree of crystallinity of the unstretched amorphous part of the bottom of the bottle increases, and the Since the strength is improved, it is possible to prevent cracks from forming at the bottom due to the internal pressure of the gas-containing bottle. Furthermore, it is possible to reduce the dissolution of moisture, chemicals, solvents, etc. into the material, and it is possible to prevent cracks from occurring at the bottom of the bottle due to external factors such as temperature, moisture, chemicals, solvents, etc. Effects of the Invention: The method for manufacturing a saturated polyester bottle according to the present invention involves stretching and blow-molding a saturated polyester preform to form a bottle, and then heat-setting only the bottom of the bottle. Because of this, it has excellent stress crack resistance, and no cracks will occur at the bottom due to external factors such as temperature, moisture, chemicals, and solvents. [0073] The present invention will be explained below with reference to Examples.
The present invention is not limited to these examples. In this specification, the stress crack resistance of the bottle is evaluated as follows. [Evaluation of stress/crack resistance] After filling a bottle with 1480 ml of water, the water was diluted with citric acid.
The CO2 concentration was adjusted to 4 gas volume using the baking soda method. Thereafter, the bottle was left in an oven at 38° C. and 50% relative humidity, and cracks occurring at the bottom of the bottle were visually observed every 1 day, 3 days, 7 days, and 30 days. [Example 1] Polyethylene terephthalate [J135 manufactured by Mitsui Pet Resin Co., Ltd.] was converted into M-70 manufactured by Meiki Seisakusho Co., Ltd.
A preform was obtained by molding with B injection molding machine. The molding temperature at this time was 290°C. Next, the preform is heated to a surface temperature of 90 to 100 at the center of the preform body using the attached infrared heater.
℃ and heat it to CORPOPLAST L
A petaloid bottle as shown in FIG. 1 was molded by stretch blowing using a B-01 molding machine. [0077] During stretching, only the bottom of the blow mold was heated to 170°C to 1
The bottle was heated to 80° C. and was brought into contact with the mold for 20 seconds to perform a heat setting treatment, and then the bottle was cooled to below 40° C. and then taken out from the mold. Regarding the bottle made in this way,
The stress crack resistance defined in the specification was evaluated. The results are shown in Table 1. [Example 2] A bottle was made in the same manner as in Example 1, except that the temperature at the bottom of the mold during heat setting was 180 to 200°C, and the heat setting time was 10 to 15 seconds. Created. Regarding the bottle made in this way,
The stress and crack resistance as defined in the specification was evaluated. The results are shown in Table 1. [Comparative Example 1] A bottle was prepared in the same manner as in Example 1 except that the heat setting treatment was not performed. [0082] This bottle was evaluated for stress and crack resistance as defined in the specification in the same manner as in Example 1. The results are shown in Table 1. [Table 1]

[Brief explanation of the drawing]

FIG. 1 (A) is a schematic explanatory diagram of a petaloid bottle. (B) is a schematic explanatory diagram of a round bottom bottle.

[Explanation of symbols]

1 bottle 2. Spout part 3 Upper shoulder 4 Torso 5 Bottom

Claims (1)

[Claims] 1. A method for manufacturing a saturated polyester bottle, which comprises forming a bottle by stretch-blowing a saturated polyester preform, and then heat-setting only the bottom of the bottle.