JPS5850177B2 - Method for manufacturing biaxially oriented bottles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a biaxially oriented bottle molded from a thermoplastic polyester having ethylene terephthalate as the main repeating unit and a method for producing the same, and more particularly relates to a bottle having excellent mechanical properties, gas barrier This invention relates to a method for producing biaxially oriented bottles that have excellent properties such as heat resistance, chemical resistance, and excellent protection against the contents, and also have excellent thermal stability with less deformation and shrinkage during filling with high-temperature contents. .

Thermoplastic polyester, which is mainly composed of polyethylene terephthalate, has been attracting attention for its excellent mechanical properties, gas barrier properties, chemical resistance, fragrance retention, transparency, hygiene, etc., and has been used for various containers, films, It is processed into sheets and is widely used as packaging material.

Recent advances in blow molding technology, especially two-wheel stretch blow molding technology, have made remarkable progress in its use in hollow containers such as bottles and cans.

In biaxial stretch blow molding using polyethylene terephthalate, a geometric shape (hereinafter referred to as a parison) having a cylindrical shape with an expandable upper end opening and a bottom (hereinafter referred to as a parison) made of amorphous material is generally formed by injection molding or extrusion molding. The parison is then heated to a temperature range that allows orientation, e.g., above the glass transition temperature (T9) and below the melting point (Tm), and connected to a spindle in a blow mold having the desired volumetric structure of the container. Stretching is carried out in the axial direction using an extruded rod and in the circumferential direction by blowing compressed gas.

During this stretching process, the molecular chains of the crystalline polymer (elongated in both the axial and circumferential directions, and the generation of oriented crystallized substances) improve the physical properties of the bottle, such as mechanical properties such as tensile strength and impact strength, and gas resistance. Permeability etc. are significantly improved.

However, in biaxially oriented sheets obtained by ordinary stretch forming methods, various problems arise due to distortions generated during the stretching process.

For example, when a polyester bottle after molding is stored in a hot and humid atmosphere such as in the summer, the bottle may gradually shrink and the internal volume may fluctuate, or the content may be at a high temperature near the glass transition temperature of polyester, such as 60°C or higher. When filling a product, it has the fatal disadvantage that shrinkage occurs during or after filling, making it impossible to fill the contents accurately, or causing deformation of the bottle, making it impossible to maintain its original shape. The current situation is that the range of applications is severely restricted, as this greatly reduces the commercial value of the product.

Generally, in polyethylene terephthalate molded products such as threads with a one-dimensional structure or films with a two-dimensional structure,
In order to improve heat resistance, a heat treatment called heat setting is performed after stretch forming.

The purpose of this is to change the microcrystals generated during stretching into a crystalline structure that is more stable against heat, fixing it in that alignment state, and alleviating residual strain during stretching. Molded products subjected to this treatment The heat resistance of is significantly improved.

Based on a similar idea, a method of heat setting was developed in the 4th year of the Tokuko Showa era to improve the heat resistance of stretch-oriented bottles.
This is disclosed in JP-A No. 9-3073, Japanese Unexamined Patent Publication No. 52-126376, and the like.

However, with stretch-oriented bottles molded by the normal blow molding method, it is impossible to achieve a uniform stretch ratio over the entire bottle, no matter what shape the bottle is formed into, and the spout part is not stretched at all. , is an integral molded product consisting of the neck, shoulder and bottom parts with a low stretching ratio, and the body part with a high stretching ratio.
Heat setting at 140 to 220°C as described in Publication No. 073 shows a tendency to reduce heat shrinkage, but not only does it not provide a sufficient effect, but the low-stretched areas tend to whiten due to thermal crystallization and deteriorate the aesthetic appearance of the bottle. This has the fatal drawback of impairing the

In addition, the method described in JP-A-52-126376 uses a mold that can provide temperature distribution according to the stretching ratio of each part to heat fixation, that is, low-stretched parts are set at a low temperature, and high-stretched parts are set at a low temperature. tried to prevent the whitening phenomenon by heat-setting at high temperatures, but in particular, for the stretch orientation film where the stretch ratio changes continuously from the unstretched part to the stretched part, a temperature gradient according to the stretch ratio was used. It is nearly impossible to achieve this in terms of equipment, and even if it were possible to provide a certain degree of temperature distribution, the cycle time required to heat and cool the mold would take a long time, which would significantly reduce productivity. However, if you consume a large amount of thermal energy and try to increase the density enough to provide sufficient heat resistance, whitening will occur, and conversely, if you try to avoid whitening, you will increase the density enough to provide sufficient heat resistance. In any case, a satisfactory biaxially oriented bottle cannot be obtained because of the inability to obtain an increase in the temperature, and this method is difficult to commercialize in practice.

In view of this situation, the present inventors analyzed the thermal shrinkage behavior of biaxially oriented bottles obtained under various conditions, and
The present invention has been arrived at as a result of intensive research aimed at providing a two-wheel oriented bottle with excellent heat resistance through a stretch-molding process without any heat-setting treatment.

That is, the present invention provides a method for manufacturing a bottle in which a bottomed parison with an open upper end is formed from a thermoplastic polyester having ethylene terephthalate as a main repeating unit, and then the parison is oriented in biaxial directions by blow molding at a stretching temperature. When the parison is brought to a stretching temperature, the temperature of the parison portion corresponding to the neck or neck to shoulder and bottom of the target bottle is 1 to 20°C higher than the temperature of the parison portion corresponding to the body of the bottle. After providing a temperature distribution such that the relationship between the parison structure and the blow split mold structure is in advance, the parison is fitted into the parison fitting part and the split mold is closed. The parison is designed so that at least three parts of the parison corresponding to the neck of the split mold are in close contact with the corresponding part of the split mold, and the blowing temperature is at least lower than the stretching temperature of the parison part corresponding to the body of the split mold. The parison provided with the temperature distribution is biaxially stretched blow-molded using a mold, using a stretching rod whose temperature is at least lower than the stretching temperature of the parison portion corresponding to the body, and a positive flow gas. This is a method for manufacturing axially oriented bottles.

According to the present invention, the biaxially oriented bottle has an unstretched portion, a stretched portion, and an unstretched portion, and in the portion where the stretching ratio continuously changes from the unstretched portion to the stretched portion,
Density ρ.

(g/cIrL) from the stretching start point of the unstretched part to the position of the stretched part where the density ρ(g/i) is exceeded for the first time (cfrL) and the density increase (ρ-ρ).

) d/ρ−ρ. is 100 or less (however, ρ≧ρ.

+0.026 ) biaxially oriented wings can be easily provided.

The biaxially oriented bottle obtained by the method of the present invention is disclosed in Japanese Patent Publication No. 49-3073 and Japanese Patent Application Laid-Open No. 52-126376.
It has excellent mechanical properties, gas barrier properties, chemical resistance, etc. without special heat setting treatment as disclosed in the publication, and has excellent protection performance against contents, and at the same time, it can withstand high temperature contents. These bottles have excellent thermal stability with little deformation or shrinkage when filled with items.

Therefore, it has the characteristic of being able to withstand heat such as high-temperature filling and heat sterilization.

Of course, another major feature is that it does not require heat fixation, has no problems such as whitening, and has excellent transparency.

To explain in more detail the structural and morphological characteristics of the biaxially oriented bottle obtained by the method of the present invention, the biaxially oriented bottle has a stretched portion having a thermally stable structure, as shown in FIG. A is the majority, there are very few thermally unstable stretched parts, that is, parts where the stretching ratio changes continuously from the unstretched part to the stretched part, and the other unstretched parts C.
It has the following characteristics.

Taking as an example the narrow cylindrical cap of the present invention obtained by stretch-blow molding a substantially amorphous polyester parison with an open top and a bottom, the entire body of the bottle, The shoulder and part of the bottom corner are part A above, the neck and center of the bottom of the bottle are part C above, and a small part from the neck of the bottle to the shoulder and from the center of the bottom to the corner. Part b exists only in a small portion.

The stretched part a, which has a thermally stable structure, is a part where crystallization is promoted more than molecular chain orientation during stretching, and there are crosslinking points (microcrystals) that are sufficient to suppress strain relaxation. This part has good heat resistance due to the presence of

Taking polyethylene terephthalate as an example, the density ρ of this part is the density ρ of the unstretched part.

= at least 0.026 or more greater than 1.340-1.3429/ffl, i.e. 1.366-1.36
8g/cI? L or more, preferably 1.368 or more, a test piece cut out in the axial direction and circumferential direction from the side wall in the shape of a triangle is cut in the thickness direction (edge and en).
d view), and the degree of orientation determined by measuring the orientation angle of the (100) crystal plane is usually 8 in the main orientation direction.
It is 0-90, preferably 80-85.

In addition, thermally unstable stretched parts have the following two types of molecular structure.
refers to one part.

One is a low-stretched area in which no microcrystals are observed due to stretching and the molecular chains are slightly oriented, and when heat is applied to this area, the stretched rubber contracts like relaxing.

The other is a region where molecular chain orientation is promoted more than crystallization during stretching, and heat resistance is poor because there are no crosslinking points (microcrystals) sufficient to suppress strain relaxation.

This portion has a density increase of less than 0.026 compared to the unstretched portion, that is, 1.366 to 1.368 g/cal or less, and the degree of orientation determined by the above method is 90 or more in the main orientation direction.

Furthermore, the unstretched portion C is a substantially non-oriented portion, and although it softens when treated for a short period of time at a temperature around 80°C, structural changes such as whitening do not occur, and the softening is similar to that of the unstretched portion. This can be solved by increasing the wall thickness, so the existence of this portion does not pose a problem in terms of heat resistance near 80°C.

Therefore, the biaxially oriented bottle having excellent heat resistance as used in the present invention has a structure in which the majority of the bottle consists of the above-mentioned part a, and there is very little part b, especially the low-stretched part. Another major feature is that the above-mentioned portions are fixed only in the areas that have the least effect on the volume of the hinge, that is, in extremely narrow areas near the top of the neck and the center of the bottom.

In this case, it is more preferable that the bottom of the hinge be a self-supporting bottom with a concavely curved bottom at the center as shown in FIG. 1, since this makes it easy to fix the part b.

On the other hand, the biaxially stretched orientation plate molded by a normal molding method is d/ρ-ρ.

exceeds 100 and there are many portions that are the same as described above, so even if the density of the body portion satisfies the value of ρ+0.026 or more according to the present invention, it cannot be a material with excellent heat resistance with little heat shrinkage or thermal deformation.

Note that d/ρ−ρ. is particularly preferably 80 or less.

The thermoplastic polyester having ethylene terephthalate as a main repeating unit as used in the present invention usually has an acid component of 80 mole or more, preferably 90 mole or more of terephthalic acid, and a glycol component of 80 mole or more, preferably 90 mole or more. The above refers to a polyester that is ethylene glycol, and the remaining acid components include isophthalic acid, diphenyl ether 4,4'-dicarboxylic acid, and naphthalene 1,4
- or 2,6-dicarboxylic acid, adipic acid, sebacic acid, decane 1,10-dicarboxylic acid, hexahydroterephthalic acid, and as other glycol components propylene glycol, 1,4-butadiol, neopentyl glycol, diethylene glycol, cyclohexane Dimethatol, 2,2-bis(4-hydroxyphenyl)furopane, 2,2-bis(4-hydroxyethoxyphenyl)
Furopane, or P-oxybenzoic acid as oxyacid,
It means a polyester containing P-hydroethoxybenzoic acid or the like.

In addition, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol can also be used as copolymerization components if their molecular weight is about 3,000 or less, but since using a large amount will reduce the heat resistance of the compound. It is usually preferable to use less than 2 to 3 moles of the glycol component.

The polyester in the present invention may contain additives such as colorants, ultraviolet absorbers, antistatic agents, thermal oxidative deterioration inhibitors, antibacterial agents, and lubricants in appropriate proportions, if necessary.

The thermoplastic polyester of the present invention needs to have an intrinsic viscosity of 0.55 or more, preferably 0.6 or more,
More preferably, it has an intrinsic viscosity of 0.7 to 1.4.

Intrinsic viscosity is a solution of polyester dissolved in a mixed solvent of phenol/tetrachloroethane (6/4 weight ratio).
Intrinsic viscosity measured at °C.

If the intrinsic viscosity is less than 0.55, it will be difficult to obtain a transparent amorphous molded product during parison molding, and the mechanical strength will also be insufficient.

The influence of intrinsic viscosity on the thermal shrinkage of bottles is unknown until now, but polyesters with high intrinsic viscosity shift the appropriate temperature for parison stretching to higher temperatures than polyesters with low intrinsic viscosity, and polyesters made of low viscosity Even under temperature conditions where the parison is not oriented due to the super draw phenomenon during stretching, it is possible to form biaxially oriented sheets.
In addition, polyester having a high intrinsic viscosity makes it possible to obtain bottles with high heat resistance.

The biaxially oriented hinge of the present invention can be produced by stretch blow molding under specific conditions from a substantially non-oriented and amorphous bottomed parison with an open top end obtained by a commonly known method.

That is, first, a substantially non-oriented and amorphous parison with an open top is molded from polyester by injection molding, or by cutting an extruded pipe and sealing it by heating and pressing one end. Ru.

Next, the known method is to heat the parison in a heating device to a stretching temperature, for example, in a temperature range above the glass transition temperature (Tg) and below the melting point (Tm), and then insert the drawing rod and ball into a blow mold having a desired volumetric structure. Bottles are produced by stretch blow molding with flowing gas.

On the other hand, in the present invention, when the parison is heated to the stretching temperature in manufacturing by such a known method, the neck or the part of the parison corresponding to the neck and the bottom of the desired bottle shape is After giving a temperature distribution such that the temperature is ~20℃ higher than the temperature of the parison part corresponding to the body of the bottle, the relationship between the parison structure and the blow-split mold structure is determined in advance by placing the parison in the parison fitting part. A blower designed so that when the mold is fitted and the split mold is closed, at least 3 or more parison parts of the part corresponding to the neck of the bottle are brought into close contact with the corresponding part of the split mold before stretching blowing is performed. It is manufactured by biaxially stretching blow molding a parison with the temperature distribution using a split mold using a stretching rod and a ball flow gas.

The above is a blow molding method using a so-called cold parison, but in a blow molding method using a hot parison, the above temperature distribution may be given to the parison during the cooling process to the stretching temperature.

The feature of this manufacturing method is that in order to improve the stretching effect of the shoulder and bottom parts of the bottle where the stretching ratio is small, it is best to create a clear stretching start point between the unstretched part and the stretched part. As a result of further intensive research based on the knowledge of researchers and others, we have discovered a practical manufacturing method that makes this possible.

It is known that when drawing yarn, which is a one-dimensional structure, a temperature gradient is easily created by local heating at the point of contact with the bottle or roll, and the drawing point is fixed.

However, in the case of a parison, which is a three-dimensional structure, it is technically extremely difficult to do so, and there is no knowledge to date of fixing the stretching point on the parison before stretching.

When actually heating a parison, since the heat transfer area is large, it is not possible to obtain a sudden temperature change point with just the temperature gradient that can be applied during heating. However, it is difficult to clearly fix the stretching point.

However, as in the present invention, the parison portion corresponding to the neck and bottom of the bottle is 1 to 20°C, preferably 1 to 20°C.
The parison heated to a temperature of 15°C higher than the part corresponding to the body of the bottle is preferably at least 3 degrees higher than the part corresponding to the neck of the bottle when the blow mold is closed, even if there is no sharp temperature gradient change point. By bringing the parison part of 5 or more parts into contact with the water-cooled neck of the blow mold, a significant temperature gradient can be created at the boundary between the contact surface and the non-contact surface, and the boundary surface on the non-contact side can be Since the vicinity is still at a higher temperature than the torso, the stretching point of the neck can be clearly fixed.

If the temperature difference between the neck and bottom portion and the body portion equivalent portion is less than 1° C., it will be impossible to clearly fix the stretching point, making it impossible to achieve the object of the present invention.

Furthermore, if the temperature difference exceeds 20°C, the stretch formability will be impaired, the boundary will become thinner than the body, and the physical properties of the container will deteriorate, and the shoulders and bottom will be easily stretched, causing uneven stretching on the body. This results in drawbacks such as the formation of unstretched portions and reduced thermal stability.

Also, at the bottom of the parison, after the blow mold is closed, the stretching rod contacts the bottom of the parison and stretches in the axial direction, so the contact area between the tip of the stretching rod and the bottom of the parison is rapidly cooled, and the contact area is still not in contact with the bottom of the parison. A significant temperature gradient occurs at the interface between the parts and the stretching point can be fixed in the same way as the neck.On the other hand, if a parison heated to a uniform temperature as in the conventional method is stretch-blow molded using this method, The temperature of the neck, which comes into contact when the mold is closed, and the bottom, which comes into contact with the stretching rod during stretching, decreases in temperature, and the area near the boundary on the non-contact area also becomes lower than other non-contact areas, making the stretching start point closer to the contact interface. It becomes completely impossible to come back.

For this reason, it is necessary to heat the parison part, which corresponds to the neck part that comes into contact with the mold when the blow mold is closed and the bottom part that comes into contact with the stretching rod during stretching, to a higher temperature in advance than the non-contact parts.

In this way, the biaxial stretch blow molded bottle has the same stretching effect as the body in the region from the neck to the shoulder where the stretching ratio is small and in the region from the center of the bottom to the curved portion.

Therefore, it has the advantage that not only excellent heat resistance is obtained, but also mechanical strength, gas barrier properties, etc. are improved in the portion where the drawing ratio is small.

In the present invention, the substantially amorphous bottomed parison with an open top end formed by injection molding or extrusion molding is heated in a heating oven equipped with a conventional heating element such as a block heater or an infrared heater. It takes place inside.

Furthermore, various methods are used to impart temperature distribution to the parison by heating.

For example, a parison is loaded onto a spindle that rotates and moves in a heating oven, and the parison is moved while rotating in the oven.

At that time, an auxiliary heater may be installed in addition to the normal heating element only in the heating section of the oven that corresponds to the part of the parison where a temperature gradient should be created, so that only that section can be heated to a higher temperature than other sections, or vice versa. There are various methods such as a method of adjusting the heating by installing a heat shield plate or a heat reflection plate in the oven section corresponding to the body of the parison, which has a relatively low temperature distribution, and a method of locally applying high frequency heating or dielectric heating. However, there are no restrictions on the method of providing temperature distribution to the parison.

Furthermore, the temperature distribution of the parison is given in the axial direction, and it is desirable that the temperature on the same circumference is uniform in the circumferential direction. It is desirable to heat it while rotating it by a drive device.

Stretching temperature of the parison (if stretch blow molding is performed immediately after heating, it is equal to the heating temperature.

) is usually in the temperature range of T9 or higher and Tm or lower of the polyester used, but the appropriate stretching temperature varies depending on the stretching speed, intrinsic viscosity of the polyester used, etc., and is usually 80 to 17.
0°C is preferred.

However, in order to obtain a bottle with better heat resistance, it is not necessary to apply a uniform stretching temperature; instead, the stretching temperature (' [It is more preferable to apply 5'C.

60V+85〉T-poor 60V+45... (II
) That is, the appropriate temperature for stretching is shifted to the higher temperature side as the intrinsic viscosity of the polyester increases, and it is preferable to carry out stretch blow molding as high as possible within the temperature range that allows oriented crystallization during stretching.

Therefore, in the present invention, the parison portion corresponding to the neck, shoulder and bottom of the bottle is stretch blow molded at a temperature higher than the stretching temperature (1) by 1 to 20°C, preferably 1 to 15°C.

Next, the relationship between the parison structure and the stretch blow split mold used in the present invention will be described.

FIG. 2 illustrates the relationship between the two using an example.

FIG. 2 is an explanatory view showing the state when the parison is fitted into the parison fitting portion and the split mold is closed.

Furthermore, FIG. 3 is an enlarged view of the opening, neck, and shoulder of the parison and split mold in FIG. 2.

As seen in the figure, the feature of the present invention is that at least three sections of the parison neck below the collar are already in complete contact with the closed mold before stretch blowing.

On the other hand, FIGS. 4 and 5 show an example of the relationship between the parison structure and the split mold structure, which does not apply to the present invention, that is, the conventional method.

In FIGS. 4 and 5, there is no contact between the neck and the closed split mold.

Biaxial stretch blow molding machines have two directions in which the parison is gripped during the process of heating the parison and stretching the parison in a blow mold.

That is, one type has the parison fitting portion facing upward, and in this case, the parison is fitted with the opening facing downward.

It is a so-called inverted type. The other type is a so-called suspension type fitting in which the parison fitting part faces downward and the parison opening faces upward.

When the blow split mold is closed, which is a component of the present invention, at least three spaces of the parison portion corresponding to the bottle neck are already in close contact with the blow split mold before stretching blowing is started. In order to achieve this, it is also important to appropriately select the settings of the parison and/or the blow-splitting mold for the part to be brought into close contact, depending on the above-mentioned gripping direction of the parison.

For example, in the case of a suspended type gripping direction, even if the outer diameter of the parison is designed to match the diameter of the neck of the split mold so that it comes into close contact with the blow split mold, the parison will soften when heated to the appropriate temperature for stretching. Because of this, large parisons tend to sag downwards, albeit slightly, due to the parison's own weight, and as a result, when the heated parison is inserted into the blow split mold and the mold is closed, the parts that are supposed to come into contact no longer come into contact. is normal.

For this reason, in the case of suspension type fitting, it is preferable to take measures such as designing the outer diameter of the parison at the neck part to be contacted in advance to be thicker than the corresponding part of the blow splitting mold.

On the other hand, in the case of inverted fitting, the parison tends to become thicker due to its own weight during the heating stage, so even if the outside diameter of the neck of the parison that comes into contact with it and the diameter of the corresponding blow mold neck are the same, good.

Further explaining the stretch blow molding method, the parison, which has the above temperature and has been adjusted to the stretching temperature by heating or cooling, is fitted into the parison fitting part of the stretch blow molding machine,
Close the blow mold.

At least three or more parts of the parison neck that come into contact with the mold are rapidly cooled at that point.

Immediately thereafter, the parison is stretched in the axial direction by extrusion of a stretching rod connected to the parison fitting, preferably by a factor of 2 or more, and subsequently or almost simultaneously, preferably by 5k.
It is stretched in the circumferential direction preferably by at least 3 times (the circumference ratio to the parison) using a ball flow gas of at least y/hi, especially at least 10 kg/i.

Further, the area magnification of the stretching is usually 2.5 times or more, preferably 3 times or more, relative to the parison.

In this method, the temperature distribution in the parison immediately after the drawing rod reaches the bottom of the parison is different from the temperature distribution in the temperature control stage by heating or cooling the parison, and the temperature distribution in the non-contact area immediately adjacent to the neck in contact with the mold and the drawing The temperature of the non-contact area near the bottom that is in contact with the rod is the highest, and the temperature of the contact area of the mold and the stretching rod is rapidly cooled, resulting in a large temperature at the interface between the contact area and the non-contact area. A gradient is generated, and the material is stretched around this boundary surface in a state similar to a necking phenomenon, and at the same time, it is also stretched in the circumferential direction due to the blowing of the ball flow gas.

In other words, the boundary surface having a steep temperature gradient at this time becomes the stretching fixing point.

The temperature of the blow mold and the stretching rod must be at least lower than the stretching temperature of the parison portion corresponding to the body of the hin, and preferably the Tg of the polyester.
It is as follows.

When continuously molding, the temperature of the mold also increases, so it is preferable to cool the mold with water.

The key is to make the neck and bottom of the parison cooler than the body portion as quickly as possible.

The contact between the parison part corresponding to the bottle neck and the mold not only creates a rapid temperature gradient in the neck part, but also mechanically grips the parison in the contact area (to fix the stretching point more clearly). It also has an effect.

In this case, it is preferable for the bottom of the pin to have a concave shape at the center as shown in FIG. 1, since this makes it easier to fix the stretching point.

In the biaxially oriented bottle thus obtained, the wall thickness suddenly becomes thinner immediately near the part that was in contact with the mold and the stretching rod, and the boundary between the stretched part and the unstretched part is clearly formed. .

In addition, because the transition from the unstretched part to the highly stretched part is steep,
A biaxially oriented sheet that satisfies the object of the present invention can be obtained with good reproducibility and high productivity, with almost no low-stretched parts that are most unstable against heat shrinkage.

The above has described a particularly preferable stretch blow molding in which the neck and the split mold are in contact with each other, but even if the parison structure and the split mold structure shown in FIGS. This objective can be achieved by fitting a ring made of aluminum or the like in advance to the parison portion corresponding to the neck portion of the parison and performing stretch blow molding.

The point is that the stretching points are clearly fixed at the neck and bottom, and the stretching is done in a state close to the necking phenomenon.

Hereinafter, the present invention will be explained in detail with reference to Examples.

The evaluation and measurement methods for the characteristic values of the biaxially oriented bottles listed in the Examples and Comparative Examples are as follows.

(1) Cut the bottle in the axial direction along the parting line of the blow mold attached to the numbered bottle.

1.2.3. from just below the flange of the cut bottle along the shape of the bottle at intervals of 1 crfL as shown in FIG.・・・・・・
・Add a number.

In the bottles manufactured in the examples, 0 to 8 are neck to shoulder, and 9 is
23 to 23 are the body parts, 23 to 27 are the bottom parts, and 28 is the center of the bottom part.

(II) Wall Thickness Measure the thickness at each position using a micrometer.

011) Density The density at each position number of the bottle was measured using a calcium nitrate-water density gradient tube on test pieces cut from each position of the bottle and measuring 1 to 5 fi on a side.

The measurement temperature is 30°C. 4v) Cut out a strip-shaped specimen with a width of 1 inch in the axial and circumferential directions from the side wall of the orientation bottle, and irradiate X-rays from the thickness direction (ed).
ge and end view) The degree of orientation was calculated from the measurement of the orientation angle of the (100) crystal plane in each direction.

(■) Heat shrinkage: Fill a bottle with 80°C hot water and leave it for 5 minutes.

After 5 minutes, remove the hot water, fill with 20°C water, measure the internal volume (1) after treatment, and compare it with the internal volume (VO) before treatment to determine the volumetric shrinkage rate Vs (%). Calculate using the following formula.

o-V Vs (related) = ×100 ■.

(vi) Tensile properties A dumbbell 3 arcuate test piece specified in JISK-6301 was punched out from the cylindrical part of the maximum diameter of the bottle, and tested at a tensile speed of 10 πm/min at yield and rupture using "Tensilon" manufactured by Toyo Side Cover Co., Ltd. Measure the tension and convert it into stress per unit cross-sectional area of the original sample or material.

~11) Drop test Fill a container with water from step 11 and repeatedly drop it from a height of 1.2 m onto a concrete floor with the mouth plugged and the back bent facing downwards, and check the number of falls until it breaks. .

Example 1 Pellets of polyethylene terephthalate with an intrinsic viscosity of 0.62 were dried at 130° C. under a reduced pressure of O, lmmHg for 16 hours to a moisture content of o, o]% or less, and then dried with N-95 manufactured by Nippon Steel Corporation. Using an injection molding machine, the cylinder temperature is set to 250°C - 270'C - 280°C from the hopper side,
Injection pressure is 40kg/Makoto gauge pressure, mold temperature 20℃,
A bottomed parison with an open top end was molded under molding conditions with injection and cooling cycle times of 15 seconds and 25 seconds.

The parison has the shape shown in Figure 2, and has an outer diameter of 30 m and an inner diameter of 26 m from the opening A to the lower end of the neck C.
m, and the flange B protrudes between them.

The outer diameter of the parison gradually decreases from C to the curved surface starting point E at the bottom, and the outer diameter of E is 24mm.

The total length of the parison is 140 threads, the length from A to the lower end of the collar B is 23 mm, and the length of the neck from the lower end of the collar B to C is 10 mm.

This parison is fitted into an upwardly facing parison fitting part equipped with an autorotation drive device, with the parison opening end facing downwards, and an oven equipped with a far-infrared heater and a heat reflector on 10 sides that can freely adjust the heating distribution. The parison was heated while rotating in the oven, and when the temperature distribution of the parison reached 115°C at the 0 point of the neck, 100°C at the D point of the body, and 115°C at the F point of the bottom, the parison was removed from the heating oven and stretch-blow molded. It was immediately transferred to the aircraft.

When the split mold of the stretch blow molding machine is closed, the BC of the parison neck is set in advance to be in complete contact with the split mold, and after the mold is closed, the BC of the parison neck is set in advance to be in close contact with the split mold. Stretching was performed.

The cavity structure of the blow mold is shaped like a beer bottle, and as shown in Fig. 2, the total length is 265 mm, the outer diameter of the body is 80 mm, and the internal volume is 1000 TLl.

In addition, the forming conditions for biaxial stretching blowing are stretching rod oil pressure 30k.
g/cIrL, compressed gas pressure 20kg/cr? L and the blow mold temperature are 20°C.

The bottle obtained in this way appears to have stretching fixation points near the boundary between the neck part that originally contacted the blow mold and the non-contact part, and the bottom part near the boundary between the contact part and the non-contact part of the stretching rod. A sharp wall thickness displacement point was also observed from the outside.

In addition, the density ρ of the unstretched part.

is 1.342, and ρ of the unstretched part.

ρ from the position with . +0.026 or 1.368
The distance from the neck unstretched part to the position of the stretched part having the density ρ is 1.5 crfL.

The corresponding distance from the bottom unstretched part is 1.2 CrrL,
Therefore, when this biaxially oriented bottle was filled with hot water at 80° C. and the volumetric shrinkage rate was measured after being left for a minute, it was found to be 1.35%.

Examples 2 to 4 Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.80, 1.00 and 1.21 was used, and the injection molding conditions shown in Table 1 were used to form a bottomed mold with an opening at the upper end as in Example 1. After the parison was molded, the temperature distribution shown in Table 2 was imparted to the parison in a parison heating oven.

Thereafter, biaxial stretch blow molding was performed in the same manner as in Example 1.

The characteristic values of the obtained bottle are shown in Table 2, and the high viscosity PET can be stretched at high temperatures, and a bottle with a small shrinkage rate was obtained.

Furthermore, in each bottle, a sharp wall thickness change point was observed at a position that appeared to be the stretching start point near the boundary between the unstretched part and the stretched part.

This can also be confirmed by the measurement results of wall thickness, density, and degree of orientation at each site of the bottle obtained in Example 3 shown in Table 3.

The mechanical properties are shown in Table 4.

Comparative Examples 1 to 4 Intrinsic viscosities are 0, 62.0.80.1.00 and 1, respectively
．． A bottomed parison was molded from polyethylene terephthalate No. 21 under the injection molding conditions shown in Table 1, and then each parison was heated in a heating oven to the parison temperature shown in Table 2, and biaxial stretch blow molding was performed in the same manner as in Example 1. went.

The characteristics of the obtained bottle are shown in Table 2.

Comparative Examples 1 to 4 correspond to Examples 1 to 4, respectively, and show examples in which the temperature of the parison before stretch blowing is uniform.

When the parison temperature distribution is uniform, even if one of the requirements of the present invention is met, that the parison neck is in close contact with the mold surface for at least 3 spaces, small deformation occurred in the shoulders and shrinkage was observed in the bottom.

Furthermore, as is clear from Table 3, the wall thickness of these bottles changes gently from the unstretched part to the stretched part.
No abrupt change in wall thickness was observed as in the bottle of the present invention.

Examples 5 and 6 and Comparative Examples 5 and 6.7 Polyethylene terephthalate having an intrinsic viscosity of 1.0 was injection molded under the conditions shown in Table 1, and 5 parisons having the same shape as in Example 1 were made.
I got the book.

These parisons now have a diameter of 10 mm at the neck BC of the parison in the mold closed state shown in Figures 2 and 3.
The pile is set in contact with the mold.

Of these five parisons, one parison leaves 5 points below the brim B, another one leaves 37n7IL below Suzune's, and the other parison leaves 1 distance below the brim, and the outer diameter It was cut in the outer circumferential direction using a lathe so that the 30-inch section became 29-inch sections.

In addition, the remaining two have an outer diameter of 30 by cutting the entire outer circumference of the neck BC.
The battle was set at 29van.

These parisons were used as parisons of Examples 5 and 6 and Comparative Examples 5 and 6°7, respectively.

Next, these parisons were subjected to biaxial stretch blow molding under the same stretching conditions as in Example 1, except that they were heated to have the temperature distribution shown in Table 5.

The characteristic values of the biaxially oriented bottle thus obtained are shown in Table 5, and the characteristic values of Example 3 are also listed again.

As is clear from this result, bottles whose thermal characteristics do not meet the conditions of the present invention have a large shrinkage rate, and even if the manufacturing conditions simply provide a temperature distribution when heating the parison, the mold and parison neck will close when the blow mold is closed. At least 3 contacts
It can be seen that it is difficult to prevent small deformation and contraction of the shoulder portion unless it is greater than MWt.

Example 7 After drying pellets with an intrinsic viscosity of 0.85 made of copolymerized polyethylene terephthalate/isophthalate containing 10 moles of isophthalic acid as an acid component by a conventional method, the pellets were heated to one temperature in a cylinder using an injection molding machine manufactured by Nippon Steel Corporation. Example under molding conditions: 2408C-260'C-270℃ from the hopper side, injection pressure 50 to 9/i in gauge pressure, mold temperature 20℃1, injection and cooling cycle times 15 seconds and 25 seconds. A parison having the same shape as No. 1 was molded.

This parison was heated in a heating oven to give the temperature distribution shown in Table 6, and then a biaxially oriented sheet was formed under the same stretch blowing conditions as in Example 1.

The characteristic values of the obtained bottles are shown in Table 6.

Comparative Examples 8 to 10 In the same manner as in Example 7, three parisons of copolymerized polyethylene terephthalate/isophthalate were made by injection molding.
The actual molding was done.

One of them was used as Comparative Example 8, and for the remaining two parisons as Comparative Examples 9 and 10, the outer diameter of the parison neck was cut in the outer circumferential direction in the same manner as Comparative Example 6, and the outer diameter was changed from 30 mttt to 29 mttt.

Next, these three parisons were heated to the parison temperature shown in Table 6, and then biaxially stretched and blown under the same stretching and blowing conditions as in Example 1.

The characteristic values of the obtained bottles are shown in Table 6.

Even with copolymerized polyester, bottles that do not meet the requirements of the present invention have a large shrinkage rate, and bottles with no parison temperature distribution during stretching and blowing, and bottles with no parison neck contact with the mold are accompanied by deformation. Comparative examples that did not meet the requirements were significantly deformed.

Examples 8 to 11 and Comparative Example 11 The parison obtained in Example 1 was heated in the same manner as in Example 1 to give a temperature distribution, and when blow molded and given an excessive temperature difference, the shoulders and bottom were preferentially Due to the stretching, uneven stretching occurs in the body, and unstretched portions are formed in some parts, resulting in poor hot water resistance.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal cross-sectional view taken along the parting line of a blow mold for a bottle manufactured in an embodiment according to the present invention, and a, b, and c are drawings defined in the present invention. The approximate location corresponding to the segment, and 1, 2, 3.・・・
..., 28 is numbered at intervals of 1 (1771) from just below the flange of the bottle, and is the number of the part where the physical property values were measured. In addition, Figure 2 shows the parison structure used in the present invention and the stretch-blow split. It is a schematic diagram illustrating the relationship with the mold, and is an explanatory diagram showing the state when the parison is fitted into the parison fitting part and the split mold is closed. This is an enlarged view of the opening, neck, and shoulders of the test mold.Furthermore, Fig. 4 is a schematic diagram showing the relationship between the conventional parison structure and the stretch-blow split mold corresponding to Fig. 2. can be,
FIG. 5 is an enlarged view of the opening, neck, and shoulder of the parison and split mold in FIG. 4. a: thermally stable stretched portion, b: thermally unstable stretched portion (portion where the stretching ratio changes continuously), C: unstretched portion, 29: parison, 30: fixed base, 3L32: split Mold,
33: Stretching rod, 34: Parison fitting part, A: Parison opening sound doctor B: Flange part, C: Neck part, D: Center of body, E: Bottom curved surface starting position F: Center of bottom part.

Claims (1)

[Claims] 1. After molding a bottomed parison with an open top end from a thermoplastic polyester containing ethylene terephthalate as a main repeating unit, the parison is blow-molded at a stretching temperature to produce a biaxially oriented bottle. In the method, when the parison is brought to a stretching temperature, the temperature of the parison portion corresponding to the neck or neck to shoulder and bottom of the target bottle is 1 to 20 times higher than the temperature of the parison portion corresponding to the body of the bottle. After providing a temperature distribution that increases the temperature distribution, the relationship between the parison structure and the blow split mold structure is determined in advance. The parison part, which is at least 3N or more in length corresponding to the neck of the bottle, is designed to be in close contact with the corresponding part of the split mold, and the stretching temperature is at least lower than the stretching temperature of the parison part corresponding to the body of the bottle. Using a blow mold,
A two-wheel oriented bottle characterized in that the parison provided with the temperature distribution is biaxially stretch blow molded using a stretching rod whose temperature is at least lower than the stretching temperature of the parison portion corresponding to the body of the bottle, and a positive flow gas. Production method. 2 Stretching temperature Te of the parison portion corresponding to the body of the bottle
A method for producing a biaxially oriented bottle according to claim 1, characterized in that biaxial stretch blow molding is carried out in a temperature range that satisfies the formula: "Q is a draft." 60V+852T〉60■+450.110. OI″l
(However, ■: Intrinsic viscosity of polyester)