JPH0326523A - Method and device for manufacturing heat-resistant multi-layer bottle - Google Patents

Abstract

PURPOSE:To improve heat resistance and control thermal shrinkage, by a method wherein directly after orientation blow molding, heat treatment corresponding to a rate, a degree of orientation and a thickness of heat-resistant resin in each part of a molded product is performed within a mold. CONSTITUTION:A heat-resistant resin layer 6 and polyester layer 7 are formed alternately and an opening end 16 is covered completely with the heat-resistant resin layer 6, in a mouth part 1 of a multi-layer premolded product. Then the heat-resistant resin layer 6 of the outer most layer is continued almost up to the top 5a and an outer end surface 5b of a support ring 5. A polyester layer 7 and the heat-resistant resin layer 6 are formed alternately from the outside and the undersurface 5c of the support ring 5 is comprised almost of a polyester layer 7, in a shoulder part 2. After performance of biaxial orientation blow molding with heated and pressurized air, each part of a bottle is heat-treated at a temperature of a mold while pressing the bottle against an inner wall surface of a mold by holding blown air for 3-50 seconds. Concretely, it is good that temperatures of a mouth part mold 101, shoulder part mold 102, belly part mold 103 and bottom part mold 104 are made respectively 20-60 deg.C, 95-130 deg.C, 85-130 deg.C and 60-80 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method and apparatus for producing a polyester bottle that has excellent heat resistance and extremely low heat shrinkage.

[Problems to be solved by conventional techniques and inventions] In recent years,
So-called hot-filling, in which polyester bottles are filled with liquid at 80 to 95°C, and batherizing using hot showers have come to be used, and as a result, excellent heat resistance has become required near the mouth of the bottle. This is because in a hot fill, the mouth is first exposed to the hot liquid, and in batherizing with a hot shower, the hot shower is generally poured from the top of the bottle.

However, in a polyester bottle obtained by ordinary biaxial stretch blow molding, the mouth part is left unstretched, so it lacks heat resistance and cannot be used for filling with liquid at a temperature of 80 to 95°C.

Under these circumstances, various attempts have been made to impart heat resistance to polyester bottles, and a common method in particular is to impart heat resistance by crystallizing the mouth.

Furthermore, a widely used method for imparting heat resistance to polyester bottles is to co-inject polyester and heat-resistant resin into multilayer preformed products.
This is a method of stretch blow molding, and a typical example thereof is disclosed in JP-A-63-19208. However, in this example, one heat-resistant resin layer is co-injected between the polyester layers, and there are only three heat-resistant resin layers at the open end of the preform. . Therefore, it cannot be said that the entire mouth portion has sufficient heat resistance.

For this reason, we have conducted intensive research on preformed products that can be molded into polyester bottles with multiple layers of heat-resistant resin, especially for cold mouths. The application was filed earlier (Patent Application No. 125586, 1986).

However, when applying pastelizing using hot fill or hot shower, it is desirable to have a mouth with even better heat resistance, and for this reason, it is desirable to develop a bottle that contains more heat-resistant resin near the mouth. It is rare.

In addition, heat-resistant resin is expensive, so for the body part that can be stretched and heat-set to impart heat resistance, and the bottom part that can be thickened and not directly exposed to hot showers, Heat-resistant resin is not used, but heat-resistant resin is concentrated in the mouth that remains unstretched, the transition area from the mouth that is not sufficiently stretched to the shoulder, and the shoulder that is directly exposed to hot showers from above. It is desired to develop a low-cost bottle.

By the way, a heat-resistant bottle is manufactured by stretch-blow molding a preform with a different proportion of heat-resistant resin in each part, such as placing a large amount of heat-resistant resin near the mouth and also placing heat-resistant resin on the shoulder. If you try to do so, the bottle may show a whitening phenomenon, or deformation such as deformation over time or heat shrinkage.

This is thought to be because the proportion of heat-resistant resin in each part of the bottle is different, and the stretching ratio during blow molding is different in each part of the bottle.

Therefore, an object of the present invention is to manufacture a bottle having excellent heat resistance without causing whitening, deformation over time, heat shrinkage, etc. from a preformed product in which a large number of heat-resistant resin layers are arranged especially near the mouth. An object of the present invention is to provide a method and an apparatus thereof.

[Means to solve the problem]

As a result of intensive research in order to solve the above problems, the present inventor has developed a heat-resistant product with five heat-resistant resin layers on the mouth and three heat-resistant resin layers on the shoulder. Immediately after stretch-blow molding, heat treatment is applied in the mold to match the proportion of heat-resistant resin, stretching rate, and wall thickness in each part of the molded product, making it suitable for pastelizing by hot fill or hot shower. We discovered that it is possible to create a bottle that has sufficient heat resistance and has excellent dimensional properties that do not deform when released from the mold, over time, or due to heat.
This invention has been completed.

That is, the method of the present invention for manufacturing a heat-resistant multilayer bottle comprising a polyester layer and a heat-resistant resin layer includes: (a) a mouth portion, a support ring provided at the lower end of the mouth portion, and a shoulder following the support ring; 7, having a nine-layer structure including five heat-resistant resin layers at least below the mouth part, and three heat-resistant resin layers in the shoulder part. forming a multilayer preform having a layered structure; (a) placing the multilayer preform in a blow molding mold; and (c) blowing heated and pressurized air into the multilayer preform for biaxial stretching. Blow molding is carried out, and (a) the blown heated air is held for 3 to 50 seconds, and the temperature of the inner wall of the mold in contact with the body and shoulder of the obtained bottle is 85 to 130°C, and the other parts are kept at 80°C. ℃ or less, (e) cooling the bottle by blowing a cooling fluid into the bottle, and (f) releasing the bottle from the mold.

The multilayer preformed product includes a mouth, a support ring provided at the lower end of the mouth, a shoulder following the support ring, a body and a bottom, and is made of a polyester layer and a heat-resistant resin layer. The apparatus of the present invention for manufacturing a heat-resistant multilayer bottle includes a blow molding mold, a blow mandrel attached to the mold, and a multilayer bottle attached to the center of the blow mandrel for biaxial stretch blow molding. a stretching rod inserted into the preform, the mold is composed of a mouth mold, an M part mold, a body part mold, and a bottom part mold, and the four molds constituting the mold are temperature can be set independently, and the blow mandrel has a heated pressurized air flow path and a cooling fluid flow path separated from the heated pressurized air flow path. The method is characterized in that, after blow molding is performed by blowing pressurized air into the multilayer preform, the resulting bottle is rapidly cooled by flowing a cooling fluid.

The present invention will be explained in detail below.

First, the resin used in the present invention will be explained.

As the polyester resin, a thermoplastic resin made of a saturated dicarboxylic acid and a saturated dihydric alcohol can be used. Saturated dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenyl ether-4. Aromatic dicarboxylic acids such as 4'-dicarboxylic acid, diphenyldicarboxylic acids, diphenoxyshetanediethanedicarboxylic acids, adipic acid, sebacic acid, azelaic acid, decane-i,io
- Aliphatic dicarboxylic acids such as dicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, etc. can be used. Saturated dihydric alcohols include ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol, neobentyl glycol, etc. aliphatic glycols, cyclohexanedimethanol, etc. (7) fatty glycols, 2.2-
Bis(4'-β-hydroxyethoxyphenyl)propane, other aromatic diols, etc. can be used.

A preferred polyester is polyethylene terephthalate consisting of terephthalic acid and ethylene glycol.

The polyester resin used in the present invention has an intrinsic viscosity of 0.5 to
1.5, preferably in the range 0.55 to 0.8. In addition, such polyesters are produced by melt polymerization and heat treated under reduced pressure or an inert gas atmosphere at a temperature of 180 to 250°C, or solid phase polymerized to produce low molecular weight polymers such as oligomers and acetaldehyde. Those with reduced content are preferred.

In addition, heat-resistant resins include polyarylate, polycarbonate, polyethylene naphthalate, polyacetal,
Polysulfone, polyetheretherketone, polyethersulfone, polyetherimide, polyphenylene sulfide, blend polymers of these resins and polyethylene terephthalate, blend polymers between the above heat-resistant resins, and two types of the above heat-resistant resins. A blend polymer of the above resin and polyethylene terephthalate, U Polymer (manufactured by Unitika, a blend polymer of polyarylate and polyethylene terephthalate), etc. may be used.

The polyester resin or heat-resistant resin used in the present invention may contain stabilizers, pigments, antioxidants, heat deterioration inhibitors, ultraviolet deterioration inhibitors, antistatic agents, and antibacterial agents to the extent that the purpose of the present invention is not impaired. Appropriate amounts of additives such as and other resins can be added.

Next, in order to clearly illustrate the multilayer structure of the bottle produced by the method of the present invention, the multilayer structure will be explained using a preform that can be molded into the bottle of the present invention.

FIG. 1 is a schematic cross-sectional view showing an example of a multilayer preform to which the method of the present invention can be applied (however, the layer structure is omitted), and FIG. 2 is a multilayer preform shown in FIG. FIG. 2 is a partially enlarged view showing in detail an example of a multilayer structure of a molded product.

The multilayer preform consists of a mouth part 1, a shoulder part 2, a support ring 5 provided between them, a body part 3, and a bottom part 4. The mouth part 1, the support ring 5, and the shoulder part 2 are It has a multilayer structure consisting of a heat-resistant resin layer and a polyester layer.

As shown in detail in FIG.
L consists of a mouth end sealing part 13 between the open end l6 and the first thread 17B, and a thread/locking ring part l4 between the first thread l7 and the locking ring l8. Further, the combined portion of the screw tightening portion Ill and the support ring portion l2 (mouth portion 1 + support ring portion 5) is called a head pressure addition portion 15, and a large head pressure is applied during capping. Note that the head pressure applying portion 15 is a portion that is not stretched even by stretch blow molding.

The mouth II having such a shape has a multilayer structure in which heat-resistant resin layers 6 and polyester layers 7 are alternately formed. (6a to 6e). On the other hand, the polyester layer 7 exists between each heat-resistant resin layer, and
It is layered.

The open end 16 is entirely covered with the heat-resistant resin layer 6. Further, the outermost heat-resistant resin layer 6a is substantially continuous to the upper surface 5a and outer end surface 5b of the support ring 5.

On the other hand, the shoulder IS2 includes, in order from the outside, a polyester layer 7a, a heat-resistant resin layer 6b, a polyester layer 7b, and a heat-resistant resin layer 6.
c, a polyester layer 7c, a heat-resistant resin layer 6d, and a polyester layer 7d, and here there are three heat-resistant resin layers.

Incidentally, the bottom surface 5c of the support ring 5 and the root portion of the ring are substantially made of a polyester layer. Since there is no relatively fragile heat-resistant resin layer at the base of the IJ ring 5 that is subjected to stress in this way, it is possible to prevent the support ring 5 from breaking.

Although there is no particular restriction on the thickness of the heat-resistant resin layers 6a to 6e,
The proportion occupied by the heat-resistant resin layer 6 increases as it approaches the opening end l6. The proportion of the heat-resistant resin layer 6 is preferably as follows in terms of weight ratio.

Mouth end seal part 13 (first screw thread l7 from open end 16
) - 70% or more screw tightening part 11 (from open end l6 to the lower end of locking R18) - 40% or more head pressure applying part 15 (from open end 16 to support) IJ
By defining the proportion of the heat-resistant resin layer 6 in this way, the ratio of the heat-resistant resin layer 6 is 8.
Hot fill filled with liquid at 0~95℃, 70~8℃
The bottle can be made to be able to sufficiently withstand batherizing, which involves applying a hot shower at 0°C for about 30 minutes from above the bottle. In addition, the more preferable ratio of the heat-resistant resin layer 6 is:
80-90% and 50-60% in the above four parts respectively
%, 40-50%, and 5-10%.

Note that the multilayer preformed product described above can be molded by the following method.

The multilayer preform can be molded by a co-injection molding method, which uses a hot runner nozzle schematically shown in FIG. This can be done by setting as illustrated in FIG.

First, the hot runner nozzle 30 shown in FIG. 3 has two channels A and B, and the channel A is further connected to a central linear channel A
1 and a cylindrical flow path A2 provided on the outside thereof. In addition, the flow path B is connected to the above two flow paths A1 and A.
It is provided in a cylindrical shape between the two.

A check valve 31 is provided at the upper end of the central flow path A1, and the check valve 31 is movable up and down depending on the difference in resin pressure between the flow path A1 and flow path B. When the temperature is high, the flow path B can be opened. The flow path B opens into the flow path A1, and the flow path island and the flow path ^2 merge above and exit the hot runner nozzle 30, communicating with the cavity 41 of the injection mold 40.

The manufacturing process of a multilayer preformed product using such a hot runner nozzle 30 is shown in the co-injection program shown in FIG. 4 and the schematic diagrams showing the co-injection states shown in FIGS. I will explain along. Note that in this example, polyester resin is flowed in channel A, and heat-resistant resin is flowed in channel B.

First, in step 1, polyester resin is injected from channel A. At this time, the check valve 3 of the hot runner nozzle 30
1 is closed by the injection pressure of the polyester resin, as shown in FIG. 5(a), and only the polyester resin is injected from the channels A and A2.

Next, in step 2, the injection rate of the polyester resin is lowered. Further, in step 3, heat-resistant resin is injected from channel B while continuing injection of polyester resin in the same manner as in step 2. At this time, since the injection pressure of the heat-resistant resin is higher than the injection pressure of the polyester resin, the chuck valve 31 opens according to the difference, and the heat-resistant resin is injected by that amount.

The heat-resistant resin injected in step 3 is shown in Figure 5 (b).
As shown in FIG. and A2, two polyester resin layers 70a, ? Proceed between Obs.

At this time, the heat-resistant resin layer 60 advances between the two polyester resin layers 70a and 70b without coming into contact with the inner wall of the mold, so the resin temperature decreases little and fluidity is high. Therefore, it moves at a faster speed than the polyester resin layers 70a and 70b.

Furthermore, in step 4, the injection rate of the polyester resin is increased without stopping the injection of the heat-resistant resin. Then, in Figure 5 (
As shown in c), in addition to the polyester resin layers 70a and 70b injected in step 3, new polyester resin layers 70C and 70d advance inside the resin.

At this time, the check valve 3l is somewhat closed due to the injection pressure of the polyester resin, so that the heat-resistant resin is injected thinly. In addition, polyester resin layers 70C and 70d
Because it moves between the resin layers, it moves at a faster speed than the polyester resins 70a and 70b.

Next, in step 5, the injection of heat-resistant resin is stopped, and enough polyester resin is injected to fill the mold ((a) in Figure 5), and finally the pressure inside the mold 40 is adjusted (maintenance is maintained). pressure) (Step 6) and complete the injection.

If a multilayer preform is molded using the co-injection program described above, at least the lower part of the mouth part 1 will have a 9-layer structure (5 layers of heat-resistant resin), and the shoulder part 2 will have a 7-layer structure (5 layers of heat-resistant resin). Three resin layers are formed. The reason for this will be explained below with reference to schematic diagrams (FIGS. 6(a) to 6(e)) showing the tip of the co-injected resin layer.

In step 3, as shown in FIG. 5(b), when the heat-resistant resin is injected between the two polyester resin layers 70a and 70b, the heat-resistant resin layer 60 is formed between the two polyester resin layers 70a and 70b. However, since the speed of the heat-resistant resin layer 60 flowing in the center is faster, the heat-resistant resin layer 60 approaches the tip 50 of the polyester resin, as shown in FIG. 6(a). As shown in FIG. 6(b), the heat-resistant resin layer 60 is made of polyester resin layers 70a and 70b.
and comes to occupy the tip 950 of the resin layer.

At this point, the resin layer has a three-layer structure of polyester resin layer 70a/heat-resistant resin layer 60/polyester resin layer 70b, but as shown in FIG. Gushing polyester resin layer 7
It comes to cover the tips of 0a and 70b. That is, the two polyester resin layers 70a and 70b advance inside the heat-resistant resin 60, and therefore a portion of the heat-resistant resin 60 remains near the inner wall surface of the mold. At this point, the resin layer has a five-layer structure of heat-resistant resin layer 60a/polyester resin layer 70a/heat-resistant resin layer 60b/polyester resin layer 70b/heat-resistant resin layer 60c.

Next, in step 4, the heat-resistant resin and polyester resin are co-injected as shown in FIG. 5(c). Since the new polyester resin layers 70c and 70d advance between the resin layers, they advance faster than the two preceding polyester resin layers 70a and 70b, as shown in FIG. 6(d). Furthermore, since the fluidity of the heat-resistant resin layer portions in contact with the polyester resin layers 70a and 70b has decreased due to a slight decrease in temperature, the polyester resin layers 70c and 70d will progress faster than that. Therefore, the outside of the heat-resistant resin layer 60 is left between the polyester resin layers 70a and 70c and between the polyester resin layers 70b and 70d, and finally, as shown in FIG. 6(e),
New heat-resistant resin layers 60d and 60e are respectively formed. Therefore, the resin layer consists of 5 layers of heat-resistant resin 60
It has a nine-layer structure including layers a to 60e.

In this way, by appropriately setting the amount and timing of the injected resin in consideration of the volume of each part of the cavity in the mold, it is possible to include five heat-resistant resin layers at least in the lower part of the mouth part 1. Multilayer preforms with a nine-layer structure can be produced. The three heat-resistant resin layers provided on the shoulders of the multilayer preform are the heat-resistant resin layer 6 in FIG. 6(e).
0d, 60b and 60e.

As is clear from the above explanation, the conditions for forming five heat-resistant resin layers at least on the lower part of the sore throat are to perform the process of step 4 in FIG. By increasing the injection rate of the polyester resin without stopping the injection of the resin, the phenomena shown in FIG. 6 (6) to (e) are caused. On the other hand, if the injection rate of the heat-resistant resin is stopped and the injection rate of the polyester resin is increased, the heat-resistant resin layer 60b in the center will not be maintained long enough and will become shorter as it progresses inside the cavity. (Because the heat-resistant resin layer 60b is located at the most central position), it will disappear when a cold sore has been reached, and the number of heat-resistant resin layers will be four in total.

In addition, in manufacturing such a multilayer preformed product, it is necessary to firmly specify the cylinder temperature, cylinder pressure, viscosity difference between the polyester resin and the heat-resistant resin, etc. at the time of injection. In particular, the viscosity of resin is greatly affected by temperature, so
It is important to keep the temperature of the resin constant. For example, when using U polymer as the heat-resistant resin and polyethylene terephthalate as the polyester resin, the resin temperature of the U polymer should be 270 to 310 t, and the temperature of the polyethylene terephthalate should be kept constant. It is preferable to set it as 260-300 t:. More preferred resin temperatures are 280-295°C for U polymer and 270-285°C for polyethylene terephthalate.

As explained above, first, apply 50% to at least the lower part of the sore throat.
By molding a multilayer preformed product having a 9-layer structure with two heat-resistant resin layers and a seven-layer structure with three heat-resistant resin layers on the shoulders, and then stretch-blow molding this. , manufactures heat-resistant multilayer bottles.

FIG. 7 is a cross-sectional view schematically showing an example of a stretch blow molding apparatus that can be used to carry out the method for manufacturing a heat-resistant multilayer bottle of the present invention. This device has a mouth type 101
A stretch blow molding mold 100 consisting of a shoulder mold 102, a body mold 103, and a bottom mold 104; a blow mandrel 105 that can be attached to the mouth mold 101 in a sealed state; stretched rod 10
6, a fixing block 116 attached to the upper end, and a stretching rod fixing block 117. Here, the stretching rod 106 is positioned at the center of the blow mandrel 105 by the stretching rod slide sleeve 112. In addition, the Broman Drel 105 has a cylindrical shape taB105a extending from the mouth mold 101 into the cavity of the mold 100.
The cylindrical portion 105a has a length that reaches near the top of the shoulder of the bottle. by this,
The blown air flows into the preform without directly hitting the shoulder of the multilayer preform, so even if the blown air undergoes so-called adiabatic expansion, the area around the shoulder of the molded product will not be cooled. This prevents whitening near the shoulder of the bottle being molded.

A stretching rod 106 passes through the center of the blow mandrel 105, and flow channels 108 and 109 are formed around the stretching rod 106. A sheath heater 110 is provided in the flow path 108, and a separation sleeve 10 is provided between the flow paths 108 and 109.
7 is provided. Further, the stretching rod l06 has a tubular shape through which a cooling fluid can flow, and a plurality of holes 111 for blowing out gas are provided in the portion that projects into the mold. Note that the stretching rod 1
06 has an opening 113 in a fixed block 117, and the opening 113 is connected to a cooling fluid source (not shown) via a vibrator or the like (not shown) having a valve. have openings 115 and 1.14 in the fixed block 116, respectively, and the opening 114 is connected to a relief valve (not shown) via a pipe or the like (not shown) having a valve at its end. The 115 is connected to a pressurized air source (not shown) via a vibrator or the like (not shown) having a valve.Inflow of heated pressurized air and cooling fluid;
When venting air, a gas flow path is established by appropriately opening and closing a plurality of valves attached to each pipe.

A multilayer preform is placed in the mold 100 of such an apparatus, and stretch blow molding is performed as follows.

First, pressurized air flows into the flow path 108 from the opening 115, and is discharged from the hole in the sleeve 112 while being heated to a predetermined temperature by the sheath heater 110, thereby stretching the multilayer preform. At this time, as the multilayer preform expands, the stretching rod 106 moves into it. In addition, at this time,
The temperature of the heated and pressurized air for biaxial stretch blow molding is 50°C or higher, preferably about 80-100°C, and the pressure is 15-100°C.
50kg/cd, preferably 2(]-40kg
/ctl.

The reason why the stretch blow molding is performed using heated air is to prevent the whitening phenomenon of a portion such as the M portion that is made up of a polyester layer and a heat-resistant resin layer.

After performing biaxial stretch blow molding with heated and pressurized air, each part of the bottle is heat-treated at the temperature of the mold while holding the blown air for 3 to 50 seconds to press the bottle against the inner wall surface of the mold. do. Specifically, the mouth part mold 101 of the mold 100 contacts the mouth part of a multilayer preform that contains a large amount of heat-resistant resin and is hardly stretched, and the N part mold 102 contains some heat-resistant resin and has a middle part that is not stretched. The body part mold 103 contacts the body part of the multilayer preform which does not contain heat-resistant resin and is stretched the most, and the bottom part mold 10
4 does not contain a heat-resistant resin, has a low stretching rate, and comes into contact with the bottom of the thick multilayer preform. Here, each 8 of the mold 100 (
The mouth mold, shoulder mold, paulownia part mold, and bottom mold are each held at a predetermined temperature, and the bottle is heat-treated at four different temperatures. The temperature of each mold is set in consideration of the difference in the proportion of heat-resistant resin and the stretching rate in each part of the multilayer preform used. Specifically, although it varies somewhat depending on the type of heat-resistant resin used, the temperature of the mouth mold is 20 to 60 °C, the temperature of the shoulder mold is 95 to 130 °C, and the temperature of the body mold is 85 to 130 °C. The temperature of the bottom mold is 60-8
It is preferable to set the temperature to 0°C. Here, the temperature of the shoulder mold is preferably set to be equal to or higher than the temperature of the body mold in order to prevent whitening of the heat-resistant resin layer.

In the next step, heated air is passed through the opening 1 through the flow path 109.
Air is evacuated from 14 and the bottle is quenched by blowing cooling fluid through the stretching rod. This rapid cooling makes it possible to significantly reduce deformation of the molded bottle when it is released from the mold, thereby making it possible to obtain dimensional stability of the bottle.

The cooling fluid flows into the stretching rod 106 through the opening 113 at a constant pressure. As mentioned above, the stretch rod 106
A large number of holes 111 are provided at the tip (the part inserted into the multilayer preform), so that cooling air is discharged into the stretch-blow-molded bottle to cool the bottle. The temperature of the cooling fluid is below 50°C, preferably between 5 and 20°C.
℃, and the pressure is 0 to 30 kg/cal, preferably 5 to 15 kg/cd.

Note that as the cooling fluid, either cooling air, liquid nitrogen, or a gas obtained by vaporizing it can be used.

After cooling, the cooling fluid flows through the flow path 10 in the mandrel 105.
9 and exits through the opening 114, the stretch blow molded bottle is always in contact with fresh cooling fluid and is rapidly cooled. At this time, the pressure level of the cooling fluid is kept constant by the relief valve connected to the opening 114. Usually, the cooling time is about 1 to 10 seconds in the case of cooling air, and about 1 to 5 seconds in the case of liquid or vaporized nitrogen gas.

The temperature of the molded container is cooled down to about 60 to 90°C by rapid cooling.

After quenching, the bottle is quickly released from the mold before being reheated using a blow mold, and a heat-resistant multilayer bottle 120 as shown in FIG. 7 can be obtained.

According to the method described above, it is possible to manufacture a bottle with excellent heat resistance, which has multiple heat-resistant resin layers on the mouth B1 and the shoulder portion 2. This is because the hottest parts during the hot fill or busterizing process are the mouth and shoulder of the bottle. On the other hand, although the heat-resistant resin layer is not substantially formed on the body and bottom of the bottle, the heat treatment described above is sufficient because they can withstand the temperature conditions of hot fill or busterizing. Furthermore, since heat-resistant resin is relatively expensive, the cost of the entire bottle can be reduced by not forming a heat-resistant resin layer on the body and bottom.

In the above explanation, the part with five heat-resistant resin layers is at least the lower part of the sore, but in other parts of the sore, adjacent heat-resistant resin layers may fuse together depending on the injection conditions. Sometimes there are. However, even in that case, since the proportion of the heat-resistant resin layer is large, it is clear that the mouth portion has sufficient heat resistance. Therefore, it is not necessary that the entire mouth part has five heat-resistant resin layers, but it is sufficient to have five heat-resistant resin layers at least at the lower part of the sore mouth.

〔Example〕

The present invention will be explained in further detail by the following examples.

Example 1 Mitsui PET as polyethylene terephthalate resin
J 125 (manufactured by Mitsui Petrochemicals) and a blend polymer of polyethylene terephthalate and polyarylate (U-polymer 8400, manufactured by Unitika) as a heat-resistant resin (hereinafter referred to as U-polymer), multi-layer molding was performed by co-injection molding. The preform was molded.

The injection molding equipment is ASB650 manufactured by Nissei ASB Machinery.
Using an NHT type, a hot runner nozzle shown in FIG. 3 was connected, and a multilayer preform was molded according to the co-injection program shown in FIG. 4.

At this time, the injection barrel temperature on the polyethylene terephthalate side was 272°C, and the injection barrel temperature on the U polymer side was 284°C. The injection rate of polyethylene terephthalate was increased from 7.74 g/sec in step 1 to 1.8 g/sec in steps 2 and 3, from 1.8 g/sec to 2.8 g/sec in step 4, and to 2.8 g/sec in step 5. 8g/
held seconds. The U polymer was adjusted to a maximum of 2.8 g/sec in steps 3 and 4.

The obtained multilayer preform was cut in the axial direction and its cross section was observed. As a result, as shown in Figure 2, the lower part and the shoulder part of the bad mouth have 9 layers (5 heat-resistant resin layers) and 7 layers (3 heat-resistant resin layers), respectively. Admitted. In addition, the proportion of U polymer in each part of the multilayer preform is 85% in the mouth end sealing part 13, and 85% in the screw tightening part l.
1, 44% at the head pressure applying section 15, and 4% at the shoulder section 2.

Next, the obtained multilayer preform was placed in a stretch blow molding mold 100 shown in FIG. Mouth mold 1 of this mold
The temperatures of the 0l1 shoulder mold 102, body mold 103, and bottom mold 104 were set to 40°C, 120°C, 105°C, and 70°C, respectively.
℃, and while inserting the stretching rod 106 into the preform, heated compressed air at 80° C. and 30 kg/cut was blown out to carry out stretch blow molding. The air blown at this time is 1
After holding for 8 seconds, the air was vented. After that, 25℃, 10k
Cooling air of g/cj was blown out from the stretching rod 106 to perform cooling and obtain a heat-resistant multilayer bottle.

The obtained heat-resistant multilayer bottle was subjected to hot filling at 83 to 87°C and batherizing at 65 to 70°C, and it was found that the bottle had good heat resistance at the mouth and shoulder. Ta.

〔Effect of the invention〕

As detailed above, in the method of the present invention, the mouth, shoulder, body, and bottom of a blow-molded bottle are heat-treated at different temperatures, so the proportion of heat-resistant resin varies in each part of the bottle. Even with such a structure, a bottle with excellent heat resistance that does not undergo thermal deformation or deformation over time can be manufactured without causing any whitening phenomenon.

Therefore, even a bottle that has five heat-resistant resin layers on the mouth and three heat-resistant resin layers on the shoulder, but no heat-resistant resin layers on the body or bottom, can be easily manufactured by stretch blow molding. can. Due to the heat-resistant resin layer disposed at the mouth and shoulder, such a bottle has sufficient heat resistance to be applied to pasteurizing by hot fill or hot shower.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a multilayer preform to which the method of the present invention can be applied, and FIG. FIG. 3 is a cross-sectional view showing an example of a hot runner nozzle used to produce a multilayer preform; FIG. 4 is a partially enlarged sectional view showing an example in detail; FIG. 5 is a graph schematically showing the process, and FIGS. 5(a) to 5(d) are partial schematic cross-sectional views showing a state in which heat-resistant resin and polyester resin are co-injected;
Figures (a) to (e) are schematic diagrams showing how a multilayer structure is formed by heat-resistant resin and polyester resin, and Figure 7 shows an apparatus for manufacturing a heat-resistant multilayer bottle according to an embodiment of the present invention. FIG. 1...Mouth 2...Shoulder 3...Body 4...Bottom 5...Support rings 6.6a to 6e...Heat-resistant resin layer 7. 7a to 7d...Polyester layer 11...Screw tightening part 12...Support ring part Mouth seal part Screw Locking ring part Head pressure applying part Hot runner nozzle Check valve Injection mold cavity Stretch blow molding metal Mold mouth mold Shoulder mold Body mold Bottom mold Blow mandrel Stretching rod, channel, sheath heater, hole 114. 115 ・Opening part・Blow mandrel fixing block・Stretching rod fixing block 13・ 14・ l5・ 30・ 31・ 40・ 41・ 100 101 102 103 104 105 106 108 . 109 110 111 113. 116 117 120 A,,A. , B. Heat-resistant multi-layer bottle/hot filler flow route application agent Dainichi

Claims (4)

[Claims] (1) In a method for manufacturing a heat-resistant multilayer bottle comprising a polyester layer and a heat-resistant resin layer, (a) a mouth, a support ring provided at the lower end of the mouth, and a shoulder following the support ring; , having a body part and a bottom part, and having a 9-layer structure including 5 heat-resistant resin layers at least below the mouth part, and a 7-layer structure including 3 heat-resistant resin layers in the shoulder part. (b) placing the multilayer preform in a blow molding mold; (c) biaxially stretching blowing by blowing heated and pressurized air into the multilayer preform. (d) Hold the blown heated air for 3 to 50 seconds and heat-treat the bottle by raising the temperature of the inner wall of the mold in contact with the body of the obtained bottle to 85 to 130 °C, (e ) quenching the bottle by blowing a cooling fluid into the bottle; and (f) demolding the bottle. (2) In the method according to claim 1, a blow molding mold consisting of a mouth mold, a shoulder mold, a body mold, and a bottom mold is used, and the temperature of the mouth mold is set to 20 to 60°C. ℃, the temperature of the shoulder mold is 95-130℃, and the temperature of the torso mold is 85-13℃.
0° C., and the temperature of the bottom mold is 60 to 80° C., and a biaxial stretch blow-molded bottle is heat-treated in the molding die. (3) A multilayer preform comprising a mouth part, a support ring provided at the lower end of the mouth part, a shoulder part following the support ring, a body part and a bottom part, and made of a polyester layer and a heat-resistant resin layer. An apparatus for manufacturing a heat-resistant multilayer bottle from a product, including a blow molding mold, a blow mandrel attached to the mold, and a multilayer preform attached to the center of the blow mandrel for biaxial stretch blow molding. a stretching rod inserted into the product, the mold consists of a mouth mold, a shoulder mold, a body mold, and a bottom mold, and each of the four molds constituting the mold has a The temperature can be set independently, and the blow mandrel has a heated and pressurized air flow path and a cooling fluid flow path that is separated from the heated and pressurized air flow path. An apparatus characterized in that air is blown into the multilayer preform to rapidly cool the bottle obtained after blow molding by flowing a cooling fluid. (4) The apparatus according to claim 3, wherein the blow mandrel has a cylindrical portion extending into the cavity of the mold, and the cylindrical portion reaches a position substantially corresponding to the upper part of the shoulder of the bottle. A device characterized in that it has a length.