JPH041772B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a polyester container with improved dimensional stability, and more specifically, it prevents deformation at high temperatures, high pressures, vacuuming, etc., and has excellent dimensional stability and appearance characteristics. The present invention relates to a polyester container having the following properties. Prior Art and Technical Problems of the Invention A bottomed preform in an amorphous state is manufactured from a thermoplastic polyester such as polyethylene terephthalate, and this bottomed preform is stretched in the axial direction of the container at a polyester stretching temperature. Containers made by blow stretching in the circumferential direction have excellent properties such as transparency, impact resistance, gas barrier properties, rigidity, and pressure resistance, as described in U.S. Pat. No. 3,733,309, and have various It has come to be widely used as a packaging container for containing liquids. However, this polyester container still has problems with heat resistance; for example, even when left in an atmosphere of 60 to 70°C for 3 to 5 minutes, it has been observed that the volumetric shrinkage rate reaches 1 to 3%. It is also recognized that at higher temperatures, thermal deformation occurs to the extent that it cannot be used practically. This tendency is also noticeable in the neck of the container, where the polyester remains substantially unoriented and in an amorphous state. In other words, the container neck is provided with a threaded portion or a stepped portion to engage with the container in order to ensure a seal with the lid, but if these do not have sufficient rigidity or If dimensional stability is lacking, a problem arises in that the desired sealing pressure cannot be secured. In order to prevent these drawbacks, methods for heat setting stretch-blown containers are disclosed, for example, in Japanese Patent Application Laid-open Nos. 51-82366, 51-107357, and 53-78268.
Although many proposals have been made, as seen in Publications No., No. 53-78267, No. 54-71, and No. 54-41973, etc., the effect of thermal stabilization obtained is relatively low, and complicated treatments are required. In this respect, it is still unsatisfactory. Additionally, as a method for improving the rigidity and dimensional stability of the neck of a container, a method is known in which an amorphous neck is whitened (crystallized) by heat treatment, as disclosed in, for example, Japanese Patent Laid-Open No. 51-53566. However, with this method, only the neck of the container turns white and loses its transparency, resulting in a significantly inferior commercial value. It is also known to irradiate polyester containers with radiation as disclosed in JP-A No. 53-125184, but simply irradiating polyester containers with radiation is insufficient to achieve sufficient dimensional stability. It is not allowed. OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a polyester container which has significantly improved heat resistance and pressure resistance, and which eliminates the above-mentioned drawbacks of the prior art. Another object of the present invention is to provide a polyester container whose heat resistance is significantly improved by chemical means. Still another object of the present invention is to provide a polyester container that has improved heat resistance, hot water resistance, pressure resistance, etc., without impairing the inherent transparency of the polyester container. According to the present invention, there is provided a container made of thermoplastic polyester, which contains at least two ethylenically unsaturated groups per molecule on the outer surface of the container, which is to be prevented from being deformed by heat and pressure. A polyester container with improved dimensional stability is provided, which is characterized by being provided with a polymerized crosslinked layer of a compound, a compound containing at least one ethylenically unsaturated group, and at least one oxirane ring per molecule, or a prepolymer thereof. According to the present invention, a compound containing at least two or more ethylenically unsaturated groups per molecule and an ethylenically unsaturated A compound containing at least one group and at least one oxirane ring per molecule, or a prepolymer thereof, is applied as a crosslinking agent, and the crosslinking agent coated polyester is irradiated with ionizing radiation or ultraviolet rays to polymerize and harden the crosslinking agent layer. A method for manufacturing a polyester container with improved dimensional stability is provided. In the present invention, the outer surface of the container whose thermal deformation is to be prevented may be any location on the outer surface of the container. For example, this location may be the outer surface of the container. In addition, if the problem is a decrease in independence due to the deformation of the bottom, the problem is the bottom, if the volumetric contraction of the body is the problem, then the body is the problem, and if the problem is deformation or lack of rigidity in the neck, the problem is the neck. It's fine. Effects of the Invention The polyfunctional compound used in the present invention has the property of being easily polymerized and crosslinked by the action of ionizing radiation, a chemical initiator, ultraviolet rays, or the like. In the present invention, by forming a layer of this polymerized crosslinked product on the outer surface of the polyester container that is to be prevented from thermal deformation, the corresponding portion of the polyester container has extremely excellent rigidity and dimensional stability. These drawbacks can be effectively eliminated. At this time, since interactions such as grafting and entanglement of molecular chains generally occur between the polymerized crosslinked layer of the compound and the base polyester layer, it is clear that the improvement in the properties is more remarkable. Moreover,
Another advantage of the present invention is that the polymerized cross-linked layer present on the outer surface of the polyester substrate only needs to be extremely thin, and the resulting improvement effect is remarkable, without losing the original excellent properties of polyester such as transparency and gas barrier properties. Never. Moreover, the treatment according to the present invention has the advantage that it can be easily carried out by applying the compound to the outer surface of the polyester substrate and polymerizing and crosslinking it in a short time. Preferred Embodiments of the Invention The present invention will be described in detail below with respect to its preferred embodiments. Polyester Container The thermoplastic polyester container to which the present invention is directed refers to thermoplastic polyester or a combination of thermoplastic polyester and other thermoplastic resin, such as a high gas barrier thermoplastic resin, which can be formed by thermoforming, stretch molding, or the like. means a packaging container obtained by combination. In the present invention, polyethylene terephthalate (PET) is preferably used as the thermoplastic polyester, but copolyesters mainly composed of ethylene terephthalate units and containing other polyester units may also be used as long as the essence of polyethylene terephthalate is not impaired. Can be used. Copolymerization components for forming such a copolyester include isophthalic acid, P-β-oxyethoxybenzoic acid, naphthalene 2,6-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, and 5-sodium. Dicarboxylic acid components such as sulfoisophthalic acid, adipic acid, sepacic acid or their alkyl ester derivatives, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, cyclohexanedimethanol, bisphenol A Examples include glycol components such as ethylene oxide adducts, diethylene glycol, and triethylene glycol. The molecular weight of the thermoplastic polyester should be sufficient to form a film, and from the mechanical strength of the container etc. Viscosity [η] is 0.01/g or more, especially
It is desirable that it is 0.05/g or more. Although the container can be manufactured by thermoforming such as extrusion molding, injection molding, melt sheet molding, melt blow molding, etc., the present invention is particularly useful for stretch molded containers. Stretch molding is the combination of the above-mentioned polyester or polyester with a gas barrier resin such as ethylene-vinyl alcohol copolymer.
At the stretching temperature, generally 85 to 115°C, the container shape is formed by blow molding, stretch blow molding, vacuum forming, plug assist molding, pressure forming, compression molding, drawing forming, drawing/iron forming, bulge forming, impact forming, etc. By utilizing the orientation effect of polyester molecules, it has the advantage of being superior in transparency, mechanical strength, and gas permeation resistance compared to ordinary thermoformed containers. A particularly suitable container is produced by stretching an amorphous bottomed preform formed by an injection molding method, an extrusion pre-blowing method, etc. in the axial direction in a blow mold at a stretching temperature, and in the circumferential direction (loop direction). This is a container obtained by expanding and stretching the material. In FIG. 1 showing an example of a suitable container (bottle), this bottle 1 has a body 2, a bottom 3 extending to the lower end of the body, and a frustum-shaped shoulder 4 extending to the upper end of the body.
and a neck portion (nozzle portion) 5 that continues to the upper end of the shoulder portion. The polyester constituting the body 2 of this bottle 1 is made by stretch blow molding in two axial directions.
That is, the molecules are oriented in the axial direction of the bottle and in the circumferential direction of the bottle. On the other hand, the neck portion (nozzle portion) 5 of the bottle 1 has an opening 6 at the upper end, and is provided with an engaging portion, a screwing portion, or a locking portion for the lid, such as a screw 7 or an engaging step portion 8, around the periphery. Furthermore, a support ring 9 is provided to support the bottle during filling and sealing. The polyester constituting the neck portion 5 is substantially unoriented. In addition, the shoulder section 4 between the neck and the torso is
It is either made of fully oriented polyester or it is made of polyester that gradually changes from a biaxially oriented state to an unoriented state from the body to the neck. The bottom portion 3 gradually changes from a biaxially oriented state to an unoriented state from the periphery toward the center. In FIG. 2, which shows an enlarged cross-sectional structure of the container wall of this bottle 1, the bottle container wall includes a polyester base 11 and an ethylenically unsaturated group provided on the outer surface of the base at least 2 times per molecule. Compounds containing at least one oxirane ring and at least one ethylenically unsaturated group per molecule, or their prepolymers (hereinafter also simply referred to as crosslinking agents)
It consists of a layer 12 of a polymerized crosslinked product. Base 1
At the interface 13 between 1 and the polymerized crosslinked product 12, the molecular chains of both may exist intertwined with each other or may form a graft bond. Crosslinking agent The crosslinking agent used in the present invention is a compound containing at least two polymerizable ethylenically unsaturated groups per molecule, a compound containing at least one oxirane ring and at least one ethylenically unsaturated group per molecule, or It is the prepolymer. Compounds containing at least two or more polymerizable ethylenically unsaturated groups per molecule include, but are not limited to, the following. () Divinyl compound divinylbenzene, () Allyl compound General formula R (--OCH ₂ CH=CH ₂ ) _o In the formula, R is a divalent to tetravalent organic group, and n is a number from 2 to 4. compound. For example, diallyl phthalate (DAP), diallyl isophthalate, diallyl adipate, diallyl glycolate, diallyl maleate, diallyl sebacate, triallyl isocyanurate, triallylphosphate, triallyl aconitate, trimellistate allyl ester,
Pyromellitic acid aryesters, etc. () Acrylic compound general formula In the formula, R ¹ is a divalent to hexavalent organic group, and R ²
is a hydrogen atom or a methyl group, m is 2 to 6
A compound that is the number of . For example, 1,6-hexanediol acrylate (HDDA), 1,6-hexanediol dimethacrylate (HDDMA), neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, ethylene glycol diacrylate (EGDA), ethylene glycol dimethacrylate ( EGDMA), polyethylene glycol diacrylate (PEGMA-A), polyethylene glycol diacrylate (PEGMA), polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, butylene glycol diacrylate, butylene glycol dimethacrylate, pentaerythritol diacrylate, 1,4 -butanediol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, tetramethylolmethanetetraacrylate, N,N,N',N'-tetrakis (β-hydroxy ethyl) ethylenediamine acrylic acid ester, etc. () Allyl-acrylic compounds Allyl acrylate, Allyl methacrylate. () Acrylamide compounds N,N'-methylenebisacrylamide, N,N'-methylenebismethacrylamide, other compounds constituting the crosslinking agent of the present invention, each containing an oxirane ring and an ethylenically unsaturated group per molecule. Compounds containing at least one () oxirane compound General formula In the formula, R ³ is an organic group having a valence of p+q, R ² is a hydrogen atom or a methyl group, and Y
is a -COO- group or a _-CH2O- group, p and q are an integer of 1 or more, and p+q is 2
and above, each is a positive integer. compound. For example, acrylic glycidyl ether, glycidyl methacrylate, glycidyl (2-methyl acrylate), glycidyl (2-butyl acrylate), glycidyl crotonate, 2,
2-bis(3-allyl-4-glycidyloxyphenyl)propane, 1,1-bis(3-allyl-4-glycidyloxyphenyl)cyclohexane, (2-allylphenyl)-glycidyl ether, (2,6- Diallylphenyl)-glycidyl ether, 1,4-diglycidyloxy-
2,6-diallylbenzene, 2,2-bis(3,5-diallyl-4-glycidyloxyphenyl)propane, (2,4,6-tri-allylphenyl)glycidyl ether, 3,3'-diallyl-4 , 4'-diglycidyloxybenzophenone, bis(3-allyl-glycidyloxyphenyl) ether, bis(3,5-diallyl-4-glycidyloxyphenyl) sulfone, and the like. There are no particular restrictions on the blending ratio of the compound containing at least two polymerizable ethylenically unsaturated groups per molecule and the compound containing at least one oxirane ring and ethylenically unsaturated group per molecule. However, compounds containing ethylenically unsaturated groups/compounds containing oxirane rings
It is preferably within the range of 10:90 to 90:10. () Prepolymer As the prepolymer which is the crosslinking agent of the present invention, a prepolymer derived from the above-mentioned compound is used, and examples thereof include epoxy acrylate. These crosslinking agents can be used alone or in combination of two or more, and can also be used in combination with monofunctional monomers to form a polymerized crosslinked product phase. Suitable examples of monofunctional monomers include, but are not limited to: Acrylic acid (AAc) Methacrylic acid (MAAc) Methyl acrylate (MA) Methyl methacrylate (MMA) Ethyl acrylate (EA) Ethyl methacrylate (EMA) Butyl acrylate (BA) Butyl methacrylate (BMA) Hexyl acrylate 2- Ethylhexyl acrylate 2-ethylhexyl methacrylate Isooctyl acrylate Lauryl methacrylate 2-hydroxyethyl acrylate (HEA) 2-hydroxyethyl methacrylate (HEMA) 2-hydroxypropyl acrylate 2-hydroxypropyl methacrylate 3-chloro-2-hydroxypropyl methacrylate N,N '-Dimethylaminoethyl acrylate N,N'-dimethylaminoethyl methacrylate N,N'-diethylaminoethyl acrylate N,N'-diethylaminoethyl methacrylate Glycidyl acrylate (GA) Glycidyl methacrylate (GMA) Carbitol acrylate Tetrahydrofurfuryl acrylate Tetrahydrofuryl acrylate Furyl methacrylate Dicyclopentadienyl acrylate Dihydrodicyclopentadienyl methacrylate Isobornia acrylate Acrylamide (AAm) Methacrylamide (MAm) N-methylol acrylamide (N-
MAM) N-diacetone acrylamide (DAAM) N-vinylpyrrolidone maleic acid itaconic acid Styrene (ST) Acrylonitrile (AN) Vinyl acetate (VAc) Vinyl toluene (VT) Polymerization curing method According to the present invention, the above-mentioned crosslinking agent , applied to the outer surface of polyester containers to prevent deformation due to heat, pressure, etc. The thickness of this coating layer is not particularly limited, but generally speaking, it is 50 to 1 μm,
In particular, a remarkable feature of the present invention is that the effect of preventing deformation due to heat, pressure, etc. can be obtained even with an extremely thin thickness such as 30 to 5 μm. If the crosslinking agent or crosslinking agent composition is a liquid with appropriate viscosity, it can be applied without dilution, or if the crosslinking agent is a highly viscous liquid or semisolid, it can be applied without dilution. It can be applied after being diluted with a solvent known per se, such as a hydrocarbon solvent or an ether solvent. Any method known per se may be used as the coating means, such as dip coating, roller coating, spray coating, brush coating, electrostatic coating, or the like. Although it is possible to polymerize and harden the crosslinking agent or crosslinking agent composition immediately after coating it on the polyester substrate, it is generally possible to polymerize and harden the crosslinking agent or crosslinking agent composition after it has been applied onto the polyester substrate, but generally after the surface layer of the polyester substrate has been thoroughly blended with the crosslinking agent or crosslinking agent composition. ,
It is desirable to carry out polymerization curing. For example, among the crosslinking agents mentioned above, those having an aromatic ring or an ester group have a property of being particularly compatible with polyester. It is recognized that when the crosslinking agent component is well compatible with the polyester, or when the surface layer of the polyester is somewhat swollen with the crosslinking agent, the grafting of the crosslinking agent onto the polyester polymer chain proceeds efficiently. In order to make the crosslinking agent familiar with the surface layer of the polyester substrate, the crosslinking agent or the crosslinking agent-containing composition is brought into contact with the crosslinking agent or the composition containing the crosslinking agent for 0.5 to 5 minutes at a temperature of 50 to 80° C. prior to the polymerization and curing operation. It is better. In the present invention, polymerization and curing of the crosslinking agent can be performed using a chemical catalyst, ultraviolet rays, etc.
This can advantageously be carried out using ionizing radiation such as electron beam irradiation. The polymerization curing method using radiation such as electron beams does not require special chemicals such as initiators, has a short curing time, and can be cured at low temperatures, so there is no heat effect on the polyester base, and only the necessary areas are irradiated. Advantages such as energy saving and excellent properties of the polymerized cured film can be achieved. As an electron beam source, the accelerating voltage is 100 to
A 3000 KV electron beam accelerator is used, and any device such as a scanning type device such as a Van de Graaf type, a curtain type device, or an electrocurtain can be used. The irradiation dose varies depending on the type of crosslinking agent and the coating thickness, but generally speaking, it is 0.5 to 50 megarads (Mrad), especially 50 megarads.
The dose that produces the desired degree of polymerization curing may be determined from a range of 3 to 3 megarads. Polymerization and curing of the crosslinking agent used in the present invention is a radical reaction. Radicals are generated in the polyester chain and/or the crosslinking agent through excitation and ionization of molecules that are irradiated with an electron beam to the crosslinking agent-coated polyester substrate. These radicals react with the crosslinking agent, and chain growth progresses, resulting in polymerization and curing. In electron beam irradiation,
Because the dose rate, therefore energy, and radical concentration are high, polymerization and curing progresses rapidly and is completed instantaneously, and the resulting polymerized and cured film has an extremely high crosslinking density, making it extremely suitable for containers. It has the advantage of providing dimensional stability and preventing deformation under high heat or high pressure. Other irradiation conditions may vary widely. For example, the dose rate can be varied, for example, in the range of 0.01 to 50 Mrad/sec, and the temperature during irradiation can be varied as appropriate, but room temperature is generally sufficient. Generally, irradiation time of 1 second or less is sufficient. Since polymerization and curing is a radical reaction, it is preferable to carry out the irradiation in an inert atmosphere such as nitrogen, but polymerization and curing may also be carried out by using air as the irradiation atmosphere and heating afterwards. Polymerization curing by electron beam irradiation is desirable from the viewpoint of workability, but gamma rays from radioactive isotopes such as cobalt-60 and cesium-137 can also be used as a radiation source. As the second most important polymerization curing method after electron beam curing,
Examples include ultraviolet curing methods. In this case, a photopolymerization initiator is included in advance in the crosslinking agent applied to the polyester base container, and the polyester coated with the crosslinking agent is irradiated with ultraviolet rays. As the photopolymerization initiator, aromatic carbonyl-containing compounds such as benzophenone, methoxybenzophenone, acetophenone, benzyl, benzoyl, benzoin ethyl ether, benzyl dimethyl ketal, and ethylene bis(benzoylbenzamide) are preferably used, but known All photopolymerization initiators can be used, and are not limited to those exemplified above. The amount of the photopolymerization initiator used may be a so-called catalytic amount, and is preferably 0.01 to 20 parts by weight, particularly 0.1 to 10 parts by weight, per 100 parts by weight of the crosslinking agent or crosslinking agent composition. The light source used for photopolymerization and curing can be any light source that emits ultraviolet rays, such as high-pressure mercury lamps, low-pressure mercury lamps, hydrogen discharge tubes, xenon discharge tubes, arc lamps, and the like. The atmosphere for ultraviolet irradiation may be in the air, and room temperature is sufficient, but in order to accelerate the polymerization curing reaction, it is recommended to heat the polyester container coated with a crosslinking agent to a temperature of 40 to 80°C. can. The duration of ultraviolet irradiation varies depending on the output of the light source and the type of crosslinking agent, but in most cases, exposure for several seconds is sufficient. The method of the present invention has the advantage that since the crosslinking agent layer is extremely thin, such as 1 to 50 μm, the polymerization and curing reaction by ultraviolet rays can be carried out extremely efficiently. In addition, for polymerization curing of the crosslinking agent, a chemical polymerization initiator,
That is, it can also be carried out using a radical polymerization initiator. As polymerization initiators, peroxides such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, and di-tert-butyl peroxide, and azo compounds such as 2,2-azobisisobutyronitrile are used. The initiator is preferably used in an amount of 0.01 to 20 parts by weight, particularly 0.1 to 10 parts by weight, per 100 parts by weight of the crosslinking agent or crosslinking agent composition. Polymerization curing of the crosslinking agent by an initiator can be carried out, e.g.
It can be carried out at a temperature of from 120° C. to a time of several minutes to several tens of minutes. It should be understood that in the present invention, the application of the crosslinking agent and the polymerization curing reaction can not only be carried out on preformed polyester containers, but also on the preform before being formed into the final container. For example, in the case of a bottle-shaped container produced by biaxial stretch blow molding, a method is employed in which a neck of the same size and shape corresponding to the neck of the final bottle is formed in advance on the brifform. It will be understood that by applying the crosslinking agent according to the present invention to the neck of the brifome and subjecting it to a polymerization curing reaction, it becomes possible to stabilize the dimensions and harden the outer surface of the neck in the final container. Characteristics of external container The processing container according to the present invention is provided with a polymerized crosslinked layer, that is, a polymerized and cured layer of a compound having a plurality of ethylenically unsaturated groups and a compound having an oxirane ring and an ethylenically unsaturated group on the outer surface of polyester. This has the advantage that its dimensional stability is significantly improved and deformation due to heat or pressure is significantly prevented. For example, a regular biaxially oriented polyester bottle
When the bottle is immersed in boiling water at 100°C, its volumetric shrinkage rate is 40% and its external shape is significantly deformed, whereas the volumetric shrinkage rate of the bottle whose outer surface has been treated according to the present invention is 40%. is less than 5%, and no external shape is recognized at all. Furthermore, when the buckling force at the bottom of the bottle is measured at a high temperature of 80°C, it is 6.4 kg/cm ² gauge for a normal polyester bottle, but for the bottle treated with the present invention, this deformation pressure is An improvement to 20.0Kg/cm ² was observed. Furthermore, when a metal cap was fastened to the neck of this bottle and the sealing pressure was measured at a temperature of 95°C, it was found that the untreated bottle leaked at a pressure of 1.0 kg/cm ² , whereas the outer periphery of the neck It was observed that the bottles treated according to the present invention maintained a sealed state even at a pressure of 10 kg/cm ² . Moreover, in the present invention, these improvements in properties are achieved when the layer of the polymerized crosslinked product is extremely thin, with a thickness of 1 to 50 μm, particularly 5 to 30 μm. This is related to the fact that the crosslinking agent used in the present invention is radically polymerizable and has a highly crosslinked (reticulated) and chain-elongated structure.
The fact that this layer is highly reticulated is due to the fact that the gel fraction of this layer reaches more than 80%, especially more than 90%, and the fact that the infrared absorption spectrum of this layer shows that C
This is confirmed by the fact that the characteristic absorption of the -C double bond or oxirane ring is hardly observed or is significantly reduced compared to the original crosslinking agent. EXAMPLE The invention is illustrated by the following example. Example 1 A preform (bottomed parison) with a diameter of φ20, a length of 120 m/m, and a thickness of 4.0 m/m was obtained by injection molding using chips of polyethylene terephthalate with an intrinsic viscosity of 0.8, and then the preform was heated to about 100°C. After heating it, it is held in a mold,
After stretching it approximately twice in the longitudinal direction, it expands in the transverse direction by blowing air at a pressure of 20 kg/cm ² , and after adhering to the inner surface of the mold and rapidly cooling it, it is taken out from the mold, with an internal volume of 1010 c.c. and a weight of 36
A stretch blow container of g was obtained. The resulting container was immersed in a divinylbenzene solution in which epoxy acrylate was dissolved and heated in an oven at 50°C. The thickness of the divinylbenzene layer (crosslinked layer) is
It was 10μ. A scanning electron beam irradiation device with an electron beam acceleration voltage of 200 KV was used in the container, and the electron beam was irradiated at 5.0 Mrad.
Irradiated. The container after irradiation was a good transparent container with no phenomena such as cloudiness. The results of the heat resistance and pressure resistance of the container are compared with a stretch-blown container that has not been irradiated with an electron beam (Comparative Example 1) and a stretch-blown container without a crosslinked layer that has been simultaneously irradiated with 5.0 Mrad (Comparative Example 2). (1) Heat resistance Measurement method: Fill a container with water at a specified temperature, and
After standing for a second, water is removed and the change in content is shown. Volume shrinkage rate (%) = Content volume before filling - Content volume after filling / Content volume before filling ×
100

[Table] (2) Compressive strength (at each filling temperature) Measuring method: Fill a container with a notch at the specified temperature to the shoulder, hold for 30 seconds,
The buckling strength of the container is measured using a Tesilon at a compression speed of 50 m/m/min.

[Table] (3) Pressure resistance measurement method: Set the internal pressure of the container to each pressure in about 5 seconds using a water pressure pump using water at a specified temperature, leave it for 15 seconds, and then reset the pressure drop in 5 seconds. and represents the amount of volume change at that time. Volumetric expansion rate (%) = Volume when internal pressure is applied -
Container content at 1 atm/container content at 1 atm x 100

【table】 [Brief explanation of drawings]

Fig. 1 is a side view showing an example of a polyester container, Fig. 2 is a side sectional view showing the cross-sectional structure of the container wall in Fig. 1, and Fig. 3 is a side view showing an example of a polyester container. The explanatory diagram, FIG. 4, is a diagram for explaining the method of measuring compressive strength in Example 2. 1 is the bottle, 2 is the body, 3 is the bottom, 4 is the shoulder,
5 is a mouth part, 11 is a polyester base, and 12 is a crosslinked material layer.

Claims (1)

[Scope of Claims] 1. A container made of thermoplastic polyester, which contains a compound containing at least two ethylenically unsaturated groups per molecule on the outer surface of the container, which is to be prevented from being deformed by heat and pressure; A polyester container with improved dimensional stability, characterized in that it is provided with a polymerized crosslinked layer of a compound or a prepolymer thereof containing at least one ethylenically unsaturated group and at least one oxirane ring per molecule. 2. On the outer surface of the container made of thermoplastic polyester, which should prevent deformation due to heat or pressure,
Coating a compound containing at least two ethylenically unsaturated groups per molecule, a compound containing at least one ethylenically unsaturated group and an oxirane ring per molecule, or a prepolymer as a crosslinking agent, and applying the crosslinking agent. A method for producing a polyester container with improved dimensional stability, comprising irradiating polyester with ionizing radiation or ultraviolet rays to polymerize and harden a crosslinking agent layer.