JPS58173627A - Method and apparatus for preparation of polyester container - Google Patents

Abstract

PURPOSE:To efficiently prepare a polyester container which is excellent in thermal shrinkability and uniform capacity by such an arrangement wherein a container is heated and blow molded by introducing pressurized steam into the passage of a metal mold, and the container is then cooled by introducing cooling water into the passage to reduce the pressure inside the container, and then the container is taken out. CONSTITUTION:A drum part metal mold 1 is provided with valves 5, 7 for introducing steam and cooling water, and a shoulder part metal mold 2 is provided with a flowrate control valve 9 for introducing cooling water and a bottom part metal mold 3 is provided with a flowrate control valve 10 for introducing heat medium, and all metal molds, the drum 1, shoulder 2 and bottom 3, are provided with passages 11, 12, 13 of steam and cooling water. All valves 5-8 are equipped with electromagnetic valves which are capable of opening or closing valves at desired time by electrical sequence. In the blow metal mold, preform of polyester resin is elongated in the axial direction at a temperature at which elongation can be made, and then it is caused to expand laterally by blowing to form a container.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyester container having good heat shrinkage resistance and an apparatus therefor. More specifically, the present invention provides a method and apparatus for efficiently manufacturing polyester containers having excellent heat shrinkage resistance, customer volume uniformity, transparency, mechanical properties, etc.

Polyester, especially polyethylene terephthalate, is a polymer with excellent physical and chemical properties, and has traditionally been widely used in fibers, films, and machinery. Strength, gas barrier properties.

Because it has excellent properties such as transparency and chemical resistance, it is attracting attention as a container for beverages, foods, cosmetics, etc. In particular, biaxially oriented polyethylene terephthalate containers formed by biaxially stretched blow molding have extremely good mechanical strength and transparency, and are widely used as containers for the above-mentioned purposes.

However, although such biaxially oriented polyethylene terephthalate containers have excellent mechanical strength, they have the drawback of poor heat shrinkage resistance.In order to improve this drawback, many proposals have been made in recent years. For example, Japanese Patent Publication No. ll85
Publication No. 1-82316, Publication No. 126376/1976 1% Disclosure No. 53-246, Special Publication No. 11853-21
A method of heat-treating the container after molding as described in Japanese Patent Application Laid-open No. 153-741i70.

JP-A-54-66968, JP-A-54-7767
No. 2, JP-A-54-86659.

JP-A-54-133563, JP-A-54-137
A method of manufacturing a container by heating a blown gold layer to a high temperature as described in Publication No. 060 etc.: I! # Kaisho 56-1040
As stated in Publication No. 32 +? A method is known in which glue molding is performed using a special liquid while controlling the temperature of the metal.

Although these methods improve the heat shrinkage resistance of polyethylene terephthalate containers, it takes a long time to obtain sufficient heat resistance, resulting in defects such as appearance defects such as cloudy appearance of the container. Moreover, when the heat treatment time is shortened, there are disadvantages such as insufficient improvement in heat resistance, the content of the container obtained is not constant, and the operation is complicated. have.

As a result of repeated studies on a method and apparatus for manufacturing polyester containers with good heat shrinkage resistance and without such drawbacks, the present inventors have discovered that containers can be manufactured under specific conditions and using a blowing mold having a specific structure. It has been discovered that the desired container can be efficiently manufactured by manufacturing the container, and the present invention has been achieved.

That is, the present invention provides 14 parts of containers by stretching a 1-reduced preform made of a polyester resin containing ethylene terephthalate as a main repeating unit in the axial direction at a temperature within the range that allows for stretching and blowing it in the lateral direction. In a method for manufacturing a polyester container in which at least a portion of the polyester container is biaxially oriented, pressurized steam is introduced into a flow path provided in a gold layer portion that shapes the container body, and the surface of the gold layer portion is oriented biaxially. Heat the temperature to 100°C or higher, perform blow molding while maintaining this temperature, and then introduce cooling water into the flow path to raise the surface temperature of the metal part to 80°C.
After cooling down, reduce the pressure inside the container, open the mold,
2. A method for manufacturing a polyester container that involves taking out the container, and 2. A blow molding wheel W equipped with a blow mold that can adjust the temperature at which the mold engraving part that shapes the container body is fitted.
At t, a heat insulating layer is provided between the carved part and the mold attachment part, a flow path for a surface temperature regulating medium is provided between the heat insulating layer and the carved part, #surface area of the flow path (A) and the thickness of the insulation layer),
Equipped with a mold in which the thermal conductivity (K) of the heat insulation layer, the weight of the mold between the heat insulation layer and the carved part (B), and the specific heat (C) of the mold material satisfy the following formulas I and ■. This is a blow molding device that measures the percentage of

A≧0.3XWXC・・・・・・−IK/TE≦
200...
......-■ However, A: Surface area of the flow path of the direct temperature control medium (aj) W: Weight of the body mold between the heat insulation layer and the carved part CI+) C: Specific heat of the material constituting the cough mold (at/11 ”C) (A and W are values per container and one side of the beef splitting mold) T: Thickness of the heat insulation layer [Rin] K: Thermal conductivity of the heat insulation layer (K”/* -br・'C) The polyester resin in the present invention is mainly a homopolymer of polyethylene terephthalate, but some of the terephthalic acid components are, for example, inphthalic acid, naphthalene dicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethane dicarboxylic acid, etc. Aromatic dicarboxylic acids such as diphenyl ether dicarpon WIl diphenyl sulfone dicarboxylic acid; hexahydroin heptatalic acid.

Alicyclic dicarboxylic acid such as hexahydroin 7-talic acid/@
, adipic acid, sepatic acid, azelaic acid, etc.; other difunctional carboxylic acids such as oxyacids such as P-β-hydroxyethoxybenzoic acid, ξ-oxycaproic acid, etc. , and/or a part of the ethylene glycol component, for example, trimethylene glycol, tetramethylene glycol, hexamelene glycol,
decamethylene glycol, neoventilene glycol,
Diethylene glycol.

1.1--:/Chlohexane dime 1,000 l'-#, 1
．． 4-Cyclohexanedimethylol, 2,2-bis(
41-! -human p-xyethoxyphenyl)propane.

Bis(4'-/-hydroxyethoxyphenyl)sulfonic acid is substituted and copolymerized with one or more polyfunctional compounds of other glycols and functional derivatives thereof within a range of 3 weight. Negative even if it is a copolymer.

The intrinsic viscosity (tV) of such polyester resin is desirably determined in consideration of the appearance of the container and the ease of imparting heat resistance, but it is preferably in the range of O,S~1, and more preferably in the range of O,F~0.85. It is preferable that the In addition, in the case of copolymers,
It is desirable to determine the intrinsic viscosity in relation to the weight ratio (P: wt'%) of the copolymer component; for example, when the weight ratio (P: wt%) of the copolymer component is 1 to 3. Special K 1-
In the case of 2, the intrinsic viscosity (IT) of the copolymer is expressed by the following formula ■ to ■ 0.6≦! V≦1・・・・・・・・・
・・m-0, IXP+ 1.2≧Iv≧-0, IXP+
0.8-・-Pi, and furthermore, the following formula:
...... ■'-0, IXP+1.0≧
IV≧−〇, IXP+0.85 ・−−−−−=−mV
It is preferable to satisfy '. If the intrinsic viscosity (!V) is too low, whitening or clouding of the container will be noticeable, and if it is too high, it will take a long time to impart heat resistance, resulting in poor moldability. Furthermore, if the polymerization ratio (P) of the copolymer components is more than 3 weight, it will take a long time to impart heat resistance.

In the present invention, the polyester resin is stretched in the axial direction and blown in the lateral direction at a temperature within the range that allows stretching in a blowing mold that is a preformed body with a bottom. l
A container in which at least a portion of I411 is biaxially oriented is manufactured, and this bottomed preform is a substantially amorphous bottomed preform (hereinafter sometimes referred to as a preform). The preform can be obtained, for example, by conventional injection molding. At that time, it is preferable that the mold be sufficiently cooled. This preform can also be obtained by extrusion molding. Here, the above-mentioned "temperature within a range that allows stretching" refers to a range in which the outer surface temperature of the preform is from the glass transition temperature (7g) of the polyester resin constituting the preform to (7g+100)C, preferably (7g+20C). The temperature is in the range of 'C to (7g + 50)'C. 1C "Substantially amorphous preform" refers to a preform that is transparent in appearance and has a smooth appearance.
For example, a part thereof has a light transmittance of 50- or more.

The preform heated (preheated) to a temperature in the above-mentioned stretchable range is first placed in a blow mold mold where the surface of the mold part that shapes the container body is heated to 100'C or higher using pressurized steam. Then stretch blow molding is performed to obtain a blow molded product. It is preferable that the six-sided temperature of the part of the blowing mold that shapes the container body (hereinafter sometimes referred to as the body mold) is 100'C or higher, particularly 140°C or higher. This allows heat resistance to be imparted to the container in a short time. If the body surface temperature is lower than 100°C, the heat resistance of the container will be insufficient.

Heating of the body mold is usually done by introducing pressurized steam into a wave path provided in the mold, but if the temperature of the steam is made as high as possible, the rate of temperature rise of the mold can be increased accordingly. It is preferable because L<, for example, 3 klF
/cjc (temperature approx. 135℃'), 6kl? /s
lG (temperature approx. 1g o”c), to1g/aj
It is preferable to use pressurized steam, such as at a temperature of about 190°C.

The time to heat set the molded product in blow molding varies depending on the mold surface temperature, but for example, if the temperature is 140°C or higher, heat setting may be sufficient while cooling the mold to 80°C or lower. In order to proceed to the next step, the introduction of water vapor may be stopped before starting the blowing. In the present invention, after stopping the introduction of water vapor, cooling water is introduced into the same flow path to raise the mold temperature to 80°C.
Take out the container after the temperature is below 8°C.
If you break the container before the temperature drops to 0°C, you can remove it!
, %l K Shrinkage and deformation of the container occurs, and it is impossible to obtain a container with uniform internal volume and shape. The preferred mold temperature when taking out the container is 65° C. or lower.

A pressurized fluid such as compressed air is normally used for the blowing expansion, and conventionally known means can be used for this purpose.

The degree of stretching (in the axial and lateral directions) is such that the refractive index in the thickness direction of the container body portion (i.e., cylindrical portion) after biaxial orientation is 1.48 to 1.53 or the area magnification of stretching is 1.48 to 1.53. It is preferable to increase the amount by 4 to 16 times. At that time, the horizontal direction magnification is 1.2 to 4 times, and the horizontal direction magnification is 2 times.
It is preferable to increase the amount by a factor of 10 to 10 times.

When molding a container, the mold temperature for the part that shapes the shoulder and/or bottom should be the same as the mold temperature for the body if the tightness of the stretching in this part is similar to that of the body. is good. However, the shoulders and/or bottom of the container usually include parts that are not as stretched (or not) as the body, and are therefore preferably at a different temperature than the body. The temperature is controlled by a separately provided mold temperature control medium, that is, a heat wire (heated steam) or a coolant (especially water) flow path (the heat medium and coolant flow paths are the same).In the present invention, The temperature during blow molding of the part is 90°C or higher, and the percentage is 95°C to 11°C.
It is preferable to set it in the range of 0'C. If the temperature is set higher than this range, the appearance will become cloudy and the mechanical strength will decrease, which is undesirable. If the temperature is set lower than this range, the resulting container will have poor heat resistance. Therefore, it is undesirable. Further, the temperature at which the container is taken out is 100° C. or lower, preferably 8 G'C or lower.

If the temperature is 111 degrees higher than the above temperature range, the shape of the container will be deformed, which is undesirable. If the amount of heat transfer is adjusted by adjusting the thickness of the heat insulating layer provided at the mold, it may be allowed to cool, but preferably a small amount of refrigerant such as cooling water is introduced into the flow path in the mold. The temperature of the mold for the shoulder part can be adjusted by the same temperature theory as for the shoulder part if the mosquito shoulder part is connected to the body part mold. In the case of a structure independent from the body mold, adjustment can be made by heating and cooling the same way as in the case of the body mold, or by continuously introducing a heating medium.

The time for cooling the mold to the temperature of the method of the present invention is preferably kept within the allowable range for the gold layer structure in order to improve the productivity of the container, and is usually within 1 minute. Preferably it is within 30 seconds.

The structure of the blow molding mold used in the apparatus of the present invention has a heat insulating layer between the body carved part and the mold attachment part, and the heat insulating layer has a thickness of 51111 or more and a thermal conductivity of I. Kmlg・h
Materials with a temperature below r°C are preferable, such as inorganic materials such as asbestos, thermosetting resins such as phenolic resin,
A fluororesin resin such as 4-fluoroethylene is used. The space between the mold engraving part and the mounting part may have a minimum necessary high thermal conductivity part such as a bolt for mounting or a metal part for regulating the spacing, and in this case, the high thermal conductivity part and the insulation It is preferable that the area between the layers is within 1/4, and there may be air as a heat insulating layer (・.

As the material constituting the carved portion, metals with good thermal conductivity are preferably used, and in particular, metals with good thermal conductivity are used.
−/a, hr, 'c or more, e.g. U metal and M and Mn
, Mg+ 81 + C- alloy or C
u metal and Cu and Zn * Pbn 8tb8i +
An alloy with metals such as Ni and Be is preferred. The density of the material of this part is preferably 4 II/- or less, such as AJ-based material, so that a polyester container with excellent heat resistance can be efficiently produced.

In the blow mold of the present invention, the dimensions A-) of the heat medium and coolant flow paths provided in the metal body, the thickness T (*) of the heat insulating layer, and the thermal conductivity K (Ktxl/m -br-"C), the weight of the heat insulating layer and the body of the metal lid W Ot> of the mold, and the specific heat C (m79℃) of the material constituting the mold are expressed by the following formula % formula % If it is outside the above range In this case, it becomes difficult to impart heat resistance to the polyester container, and it becomes difficult to efficiently produce the container.Furthermore, the range of wxc≦2 Km/°C is preferable.

The shoulder of the blowing mold is preferably thermally isolated from the body by a heat insulating layer, and the flow path for the heating medium or coolant is also preferably separate from the body.

If the bottom of the blowing mold has a structure connected to the body, it is preferable that the temperature is controlled in the same way as the shoulder and separately from the body, and if it has a structure that operates independently from the body. The same is true. However, the degree of elongation of the shoulder and/or bottom of the container is the same as that of the body, and the refractive index in the thickness direction is 1.48 to 1.
As long as the temperature is within the range of 53, the temperature control may be common to that of the body.

According to the present invention, a container with excellent heat shrinkage resistance, capacity uniformity, etc. can be efficiently obtained.

Hereinafter, the present invention will be explained in detail with reference to Examples. The measurement conditions for the main characteristic values are as follows.

Glass transition temperature (〒g): A sample that was melted at 290°C and then rapidly cooled to 0°C was measured using a differential calorimeter (using PerkinElmer's DSC-1 model).
Measured at a heating rate of 10°C/U.

Intrinsic viscosity (TV): Measured at 35°C using 0-chlorophenol as a solvent.

Orientation degree (z'n): A polarizing plate is installed in an Atsube refractometer, and the refractive index in the thickness direction and plane direction of a sample cut from a container is measured at a temperature of 25°C.
Sodium DllA was kept constant at ~, and the difference between the two values was determined by calculation.

Weight control of copolymerized components ((C) vts): Measured by gas chromatography after decomposing the polymer with methanol.

Shown below. Figure 1 shows that the body mold is heated with steam when the mold is open, and Figure 2 shows that the K111 part mold is cooled with cooling water when the mold is closed. FIG.

In FIGS. 1 and 2, 1 is a body mold.

2 is a shoulder mold, 3 is a bottom mold, 4 is a heat insulator between the body and the shoulder, 5 is a valve for introducing steam into the mold, and 6 is a valve for discharging cooling water. .

7 is a valve for introducing cooling water, 8 is a valve for discharging steam drain, 9 is a 14-section valve for flow rate when introducing cooling water into the shoulder S mold, 10 is for introducing the bottom gold WK heat medium The flow rates 111, 11, 12 and 13 are simplified diagrams of the steam and/or refrigerant water flow paths provided in the body, shoulder and bottom molds, respectively.

Valves 5 to 8 are all electromagnetic valves that can be opened and closed at predetermined times according to an electrical sequence.

Figures 3 to 1 are diagrams that explain blowing 41tm in more detail.
See Figure 3.

Insulation between, +1 on the torso and 12 on the shoulders.

13 is a part of the heat medium and/or coolant flow path at the bottom.

14 is the mold attachment part, 15 is the connection part thereof, 16 is the number between the gold part and the attachment part; a heat insulating layer provided between the mold attachment part and the connection part, 17 is the gold part and the connection part of the mold to the other parts.

The thickness of the heat insulating layer 4 is 1 cm, the thickness of the heat insulating layers 16 and 17 is each 10 cm, and the heat insulating material has a thermal conductivity of Q and 22 Ka.
A 4-fluoroethylene resin of t/*-br-''C was used.

In addition, the material of the body, shoulder, and bottom of the mold, as well as the connection to the mold attachment part, has a density of 2.74 g/d and a specific heat of 0.23 m/d.
fi, a U alloy with a thermal conductivity of 10 s Km/lbr''C was used, and the mold attachment part was made of 545C steel.

The heat medium and coolant flow paths (both have a simple diameter of lO).

rV=0.71. Tg=77℃, 75p=
Polyethylene terephthalate at 259°C was dried at 160°C for 4 hours in a dehumidifying dryer until the moisture in the chips was 0.
．． Dry chips of less than 0.01% were obtained. Using this dry chip, an 8-ounce injection molding machine (M-100 model manufactured by Meiki Seisakusho) and a hot runner set zgA mold were used to mold the straight body with an outer diameter of 25 mm, a length of 130 tll, and a wall thickness of 3. .5 g and weight 40 gr were molded. The molding conditions are cylinder set temperature 265-270℃ (resin temperature at nozzle 285℃), injection pressure soo~hooky.
/d.

The molding cycle was 35 seconds, the temperature of the gold layer cooling water was 10 to 20°C, and the residence time of the resin in the cylinder of the injection molding machine was about 2 minutes. The obtained preform was substantially amorphous with good transparency. Using this preform, the height 2 as shown in Fig. 14 to Fig.
75g.

A molded body having a prismatic bottle-like shape with a body diameter of 75 to 80 m was molded. The blow molding equipment, molding conditions, and container performance at this time were as shown in I-1 and Table-2.

In addition, the temperature of the shoulder mold was 105 to 110 °C when heating of the body mold was completed, and 70 to 90 °C when the container was taken out in Examples 1 to 8 and Comparative Examples 2 to 4 due to the passage of a small amount of 20 °C cooling water. It was adjusted so that In Comparative Examples 1 and 5, the temperature was 60 to 80°C throughout the molding.

From the results of Examples 1 to 5 and Comparative Examples 1 to 2, the heat resistance of the container is poor when the temperature at the time of blowing the body mold is 100°C or less, and the temperature at the time of unloading the container is higher than 80°C. It can be seen that the molding shrinkage rate worsens when the temperature increases. Furthermore, from the results of Examples 6 to 8 and Comparative Examples 3 to S, it is clear that if the blowing mold is outside the scope of the present invention, the molding cycle will be longer, and the benefits of the container having good appearance or heat resistance will be reduced. I understand.

Furthermore, the temperature of the bottom mold was adjusted to be approximately equal to or about 5° C. lower than the temperature of the shoulder portion by flowing a 100° C. liquid heat medium.

Comparative Example 6 A container was molded in the same manner as in Example 1, except for a pond in which cooling water was not allowed to pass through the shoulder. The temperature of the shoulder mold at the time of discharging the container was 110°C. The resulting container has deformed shoulders and a molding shrinkage rate of approx. -It was.

Comparative Example 7 A container was molded in the same manner as in Example 1, except that no heat medium was passed through the bottom. In this case, the bottom mold temperature during blow molding is approximately 80℃.
The temperature was approximately 60° C. when the container was unloaded. When the obtained container was filled with hot water of 9 S'C, the bottom part was deformed and the container became less self-supporting.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams showing an example of heating and/or cooling of the blown metal according to the present invention. Figure 3 is a front view of the blown metal heating and shoulder portion of the present invention.
The figure is a side sectional view of Fig. 3, Fig. 6 is a plan view of the shoulder, and Fig. 6 is a plan view of the shoulder.
Figures to Figures 8 are diagrams showing horizontal cross-sectional views of the Moum Z B-g and c-c' portions of the @S diagram, respectively, and Figures 9 and 10 are front views and cross-sectional views of the bottom gold layer. Fig. 11 shows a gold plate corresponding to part B-1' in Fig. 3 showing another example of the present invention.
FIG. 12 and FIG. 13 are cross-sectional views similar to FIG. 11 showing a comparison with the present invention. FIG. 14 is a half-face view and a half-sectional view showing an example of a container according to the present invention, and FIGS. 15 and 16 are horizontal cross-sectional shapes of each container body and E section in FIG. 14, respectively. FIG. Figure 6 Figure q Figure 9 Figure 10 Figure 11 Figure 1z

Claims (1)

[Claims] 1. A bottomed preform made of a polyester resin containing ethylene terephthalate as a main repeating unit is axially stretched and transversely stretched in a blow mold at a temperature within a range that allows stretching. By blowing in the direction, at least a part of the rope becomes 2
In a method for manufacturing an axially oriented polyester container, pressurized steam is introduced into a flow path provided in a mold section that shapes the container body to raise the am temperature of the gold section to 100"C.
Blow molding is performed while maintaining this temperature, and then cooling water is introduced into the flow path to cool the surface temperature of the mold part to below lIo"c, and then the pressure inside the container is A method for manufacturing polyester containers that involves reducing the temperature, opening the mold, and taking out the container. 2. The surface temperature of the mold part that shapes the shoulder and/or bottom of the container is 90°C during blow molding. A method for manufacturing a polyester container according to claim 1, characterized in that the temperature is maintained at a temperature above 100° C. or below when the container is taken out. 3. A metal carving portion that shapes the container body. In a blow molding device equipped with a blow molding mold that can adjust the surface temperature of A temperature-directing medium flow path is provided, and the surface area of the body flow path (mu), the thickness of the heat insulation layer, the thermal conductivity of the heat insulation layer (phantom), and the weight of the mold between the heat insulation layer and the carved part ( B) and specific heat (C) of the mold material satisfy the following formulas (1) and (2).A≧o, axwxc・kawa I
V-cho ≦ 200
・・・・・・・・・ ■Prompt A Double surface area of flow path of temperature control medium (aj) T: Thickness of heat insulating layer [haze] K: Thermal conductivity of heat insulating layer (i-/＠・hr・℃】W: Body mold weight between the insulation layer and the carved part [l] C: Specific heat of the material that makes up the metalwork (at/#'C) (Gang, the above person, W is one container Hit, value per half of Kinshu one side)