JPH02281909A - Multi-layered preformed item - Google Patents

Abstract

PURPOSE:To obtain the multi-layered preformed item of a bottle, which has a mouth part especially excellent in heat resistance, by a structure wherein the mouth part at its lower part has nine layered structure, in which heat resistant resin layer and polyester layer lie alternately from outside, and the outermost heat resistant resin layer is continuously formed from the opening end of the mouth part to a support ring. CONSTITUTION:The multi-layered preformed item concerned consists of a mouth part 1, a shoulder part 2, a support ring 5, which is provided between the mouth part and the shoulder part, a cylindrical part and a bottom part. Over the domain ranging from the mouth part 1 through the support ring 5 to the shoulder part 2, the preformed item has multi-layered structure consisting of heat resistant resin layers 6 are polyester layers 7. The mouth part 1 having the shape as mentioned above has multi-layered structure, in which the heat resistant resin layers 6 and the polyester layers 7 are alternately produced. Concretely, the heat resistant resin layers 6 consist at least at the lower part of the mouth part 1 of five layers 6a-6e from outside in order. On the other hand, the polyester layers 7 lie between the respective heat resistant resin layers and consist of four layers of 7a-7d. Thus, the multi-layered preformed item of a bottle, which has a mouth part especially excellent in heat resistance, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a preformed product for a polyester multilayer bottle that has excellent heat resistance.

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

Under these circumstances, various attempts have been made to impart heat resistance to polyester bottles.

The widely used method for imparting heat resistance to polyester bottles is to co-inject polyester and heat-resistant resin to create a multi-layered preform, which is then stretch-blow molded. A typical example is disclosed in JP-A No. 63-19208. However, in this example, one heat-resistant resin layer is co-injected between the polyester layers, and the opening of the preform is It has only three heat-resistant resin layers at the open end.

Therefore, it cannot be said that the entire mouth portion has sufficient heat resistance.

For this reason, we conducted intensive research on preformed products for polyester bottles that have multiple layers of heat-resistant resin, especially in the mouth area, and first developed a multilayer container that has three or four layers of heat-resistant resin over the entire mouth area. I filed an application (Patent Application 1986-1)
25586) However, when applying batherizing by hot fill or hot shower, it is desirable to have a mouth with even better heat resistance. Development is desired.

Therefore, an object of the present invention is to provide a preformed product that can be used to form a multilayer bottle with excellent heat resistance, and in particular to provide a multilayer preformed product for a bottle that has excellent heat resistance in the mouth part. It is.

[Means to solve the problem]

As a result of intensive research in order to solve the above problems, the inventors of the present invention have found that if a multilayer preformed product having five heat-resistant resin layers is formed at the mouth and stretch blow molded, hot fill or hot shower The present invention was completed based on the discovery that it is possible to produce a heat-resistant bottle that can sufficiently withstand pasteurization.

That is, the multilayer preform for a bottle of the present invention is composed of a polyester layer and a heat-resistant resin layer, and includes a mouth, a support ring provided at the lower end of the mouth, and a shoulder following the support ring. It has a body part and a bottom part, and the mouth part has a heat resistant resin layer/polyester layer/heat resistant resin layer/polyester layer/heat resistant resin layer/polyester layer/heat resistant resin layer/polyester layer/
It has a nine-layer structure of heat-resistant resin layers, and is characterized in that the outermost heat-resistant resin layer is formed substantially continuously from the open end of the mouth to the support ring.

Further, in a preferred embodiment of the multilayer preformed product of the present invention, the shoulder portion of the multilayer preformed product is formed of polyester layer/heat resistant resin layer/polyester layer/heat resistant resin layer/polyester layer/heat resistant resin layer/polyester layer. It has a 7-layer structure.

The present invention will be explained in detail below.

First, the resin constituting the multilayer preformed product of the present invention will be explained.

As the polyester resin, a thermoplastic resin consisting of a saturated dicarboxylic acid and a saturated dihydric alcohol can be used. Saturated dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalene to 1°4- or 2,6-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyldicarboxylic acids, diphenoxyethane diethane. Aromatic dicarboxylic acids such as dicarboxylic acids, adipic acid, cepatic acid, azelaic acid, decane-1,10
- Aliphatic dicarboxylic acids such as dicarboxylic acid, ring dicarboxylic acids such as cyclohexane dicarboxylic acid, and the like can be used. Saturated dihydric alcohols include aliphatic alcohols such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol, and neopentyl glycol. Glycols, aliphatic glycols such as cyclohexane dimetatool, 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 those produced by melt polymerization and heat treated under reduced pressure or an inert gas atmosphere at a temperature of 180 to 250 °C, or those produced by face phase polymerization 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 or more of the above heat-resistant resins. A blend polymer of resin and polyethylene terephthalate, U polymer (manufactured by Unitika, a blend polymer of polyarylate and polyethylene terephthalate), etc. can 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, the structure of the multilayer preform of the present invention will be explained.

FIG. 1 is a schematic cross-sectional view showing a multilayer preform according to an embodiment of the present invention (however, the layer structure is omitted).

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.

FIG. 2 is a partially enlarged sectional view showing an example of this multilayer structure in detail. The mouth part 1 consists of a screw tightening part 11 and a part of the support ring part 12, and the screw tightening part 11 has an open end 16.
and the first thread 17, and a screw/locking ring part 14 between the first thread 17 and the locking ring part 8.

Further, the partial opening portion 1+support ring 5), which is a combination of the screw tightening portion 11 and the support ring portion 12, is called a head pressure applying 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 portion 1 having such a shape has a multilayer structure in which heat-resistant resin layers 6 and polyester H7 are alternately formed. (61-6e). 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 portion 2 includes, in order from the outside, a polyester layer 7a1, a heat-resistant resin layer 6b, a polyester layer 7b, and a heat-resistant resin layer 6O.
N polyester layer 7c, heat-resistant resin layer [3d, and polyester layer 7d on the right].

Here, there are three heat-resistant resin layers.

Note that 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 support 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 the opening end 16 is approached. The weight ratio of the heat-resistant resin layer 60 is preferably as follows.

Mouth end sealing part 13 (from opening end 16 to first thread 17) 70% or more screw tightening part 11 (from opening end 16 to lower end of locking part 18) 40% or more head pressure applying part 15 (opening Support ring 5 from end 16
) ・30% or more Shoulder 2 ・・3% or more
Hot fill filled with liquid at 0~95℃, 70~8℃
The bottle can be made to sufficiently withstand batherizing, which is performed from above in a hot shower at 0°C for 30 minutes. In addition, the more preferable ratio of the heat-resistant resin layer 6 is 80 to 90% and 50 to 6% in the above four parts, respectively.
0%, 40-50%, and 5-10%.

As explained above, by providing multiple heat-resistant resin layers on the mouth portion 1 and the shoulder portion 2, a bottle with excellent heat resistance can be obtained. 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, it is sufficient to withstand the temperature conditions of 60° C. for about 20 minutes even in the above treatment. 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.

The above 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 the injection timing as illustrated in FIG.

First, the hot runner nozzle 30 shown in FIG.
, and a cylindrical flow path A2 provided on the outside thereof. Also, flow path B is the same as the above two flow paths ^1 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 A, and the check valve 31 is movable up and down depending on the difference in resin pressure between the flow path ^1 and the flow path B. Channel B can be opened when the pressure is high. Flow path B opens into flow path A, and flow path A1 and flow path A2 merge above to exit hot runner nozzle 30 and communicate with cavity 41 of injection mold 40.

The manufacturing process of a multilayer preformed product using such a hot runner nozzle 30 is illustrated by the co-injection program shown in FIG. 4 and the schematic diagrams showing the co-injection states shown in FIGS. 5(a) to (6). I will explain along. 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 chatter 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. 3, the flow passes between two polyester resin layers 70a and 70b injected from channels A and A2.

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 70 a and 70 b injected in step 3, new polyester resin layers 70 c and 70 d will advance inside the resin. At this time, the check valve 31 is somewhat closed due to the injection pressure of the polyester resin, so
The heat-resistant resin is injected in a thin layer. Furthermore, since the polyester resin layers 70c and 70d move between the resin layers, they move 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 (FIG. 5(d)).Finally, the pressure inside the mold 40 is adjusted (holding pressure). ) and complete the injection step 6).

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). A resin layer (3 resin layers) is formed. The reason for this will be explained below with reference to schematic diagrams (FIGS. 6(a) to 6(e)) showing the tips of the co-injected resin layers.

In step 3, as shown in FIG. 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(c), the heat-resistant resin layer 60 is a polyester resin layer 70a.
, 70b, and occupies the tip 50 of the resin layer. At this point, the resin layers are polyester resin layer 70a/heat-resistant resin layer 60/polyester resin layer 70b.
As shown in FIG. 6(C), the heat-resistant resin layer 60 springs out from the tip 50 and covers the tips of the polyester resin layers 70a 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(6).

In addition, the fluidity of the heat-resistant resin layer portions that are in contact with the polyester resin layers 70 a and 70 b has decreased due to a slight decrease in temperature, so the polyester resin layers 70 c and
70 d will progress faster than that. Therefore, the outside of the heat-resistant resin layer 60 is the polyester resin layer 7.
Between 0a and 70e, there is also a polyester resin layer 70b and 7
0d, and new heat-resistant resin layers 60d and 60e are finally formed, respectively, as shown in FIG. 6(e). Therefore, the resin layer has a nine-layer structure including five layers of heat-resistant resins 60a to 60e.

In this way, by appropriately setting the amount and timing of the injected resin in consideration of the volume inside the mold, a multilayer structure with a nine-layer structure including five heat-resistant resin layers at least at the lower part of the mouth part 1 can be created. Preforms can be produced. The three heat-resistant resin layers provided on the shoulders of the multilayer preform are the sixth layer.
Heat-resistant resin layers 60 d and 60 b in figure (e)
and 60e.

As is clear from the above explanation, the conditions for molding five heat-resistant resin layers at least at the lower part of the mouth 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, when the injection 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 becomes sufficiently long.

It is not maintained and becomes shorter as it progresses inside the cavity (because the heat-resistant resin layer 60b is located most centrally), so it disappears when it reaches the mouth, leaving a total of four heat-resistant resin layers. .

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 °C, and the temperature of the polyethylene terephthalate should be kept constant. The temperature is preferably 260 to 300°C. A more preferable resin temperature is 2 for U polymer.
It is 80-295°C, and for polyethylene terephthalate it is 270-285°C.

As detailed above, the part where five heat-resistant resin layers are formed is at least the lower part of the mouth, but in other parts of the mouth, adjacent heat-resistant resin layers may fuse depending on the injection conditions. Sometimes. 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 at least the lower part of the mouth part has five heat-resistant resin layers.
It is sufficient to have a heat-resistant resin layer.

〔Example〕

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

Example 1 Mitsui PETJ1 as polyethylene terephthalate resin
25 (manufactured by Mitsui Petrochemicals), and a blend polymer of polyethylene terephthalate and polyarylate (U Polymer 8400, manufactured by Unitika) as a heat-resistant resin.
A multilayer preform was molded using the co-injection molding method.

A hot runner nozzle shown in FIG. 3 was used as the injection molding apparatus, 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. In addition, the injection rate of polyethylene terephthalate was 7.74 g/s in step 1 and 7.74 g/s in step 2.
and 1.8 g/s for step 4 and 1.8 g/s for step 4
/sec to 2.8 g/sec and held at 2.8 g/sec in step 5. The U polymer was given 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, the lower part of the mouth and the shoulder part have 9 layers (5 heat-resistant resin layers) and 7 layers (3 heat-resistant resin layers), respectively, as shown in Figure 2. Admitted. In addition, the proportion of U polymer in each part of the multilayer preformed product is 85% in the mouth end sealing part 13, and 85% in the screw tightening part 1.
1, 44% at the head pressure applying section 15, and 4% at the shoulder section 2.

Using the thus obtained multilayer preform, a multilayer photo) V was produced by a stretch blowing method, and hot fill at 83 to 87°C and busterizing at 65 to 70°C were performed. It was observed that the shoulder part had good heat resistance.

〔Effect of the invention〕

As described in detail above, the multilayer preformed product of the present invention has at least the lower part of the mouth part composed of nine layers including five heat-resistant resin layers, and is almost covered with the heat-resistant resin layer from the open end to the support ring. Therefore, it is possible to provide a bottle whose mouth part has particularly excellent heat resistance. For this reason, thermal shrinkage of the mouth portion due to hot fill etc. is small, and a bottle with good sealing properties can be obtained.

Furthermore, since the multilayer preformed product of the present invention can have a seven-layer multilayer structure including three heat-resistant resin layers at the shoulder portion, the stretched blow bottle obtained from this can be pastelized using a hot shower. It has sufficient heat resistance to

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a multilayer preform according to an embodiment of the present invention; FIG. 2 is a partially enlarged sectional view of the mouth and shoulder of the multilayer preform of FIG. 1; The figure is a sectional view showing a hot runner used to produce the multilayer preform of the present invention, and FIG. 4 is a graph schematically showing the process of producing the multilayer preform of the present invention. 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 a state in which a multilayer structure is formed by a heat-resistant resin and a polyester resin. 1...Mouth 2...Shoulder 3...Body 4...Bottom 5...Support ring 11...Screw tightening part 12...Support ring 13... - Mouth seal part 14... - Screw/locking ring part 15...
・Head pressure application parts 6.6a to 6e ・・Heat-resistant resin layers 7.7a to 7d ・・Polyester layer 30 ・ ・・Hot runner nozzle 31 ・・Chuck valve 40 ・・Injection mold 41 ・・・Cavity

Claims (6)

[Claims] (1) A multilayer preformed product for a bottle consisting of a polyester layer and a heat-resistant resin layer, which includes a mouth, a support ring provided at the lower end of the mouth, a shoulder following the support ring, and a body. and a bottom part, and the mouth part has a heat-resistant resin layer/polyester layer/
It has a nine-layer structure of heat-resistant resin layer/polyester layer/heat-resistant resin layer/polyester layer/heat-resistant resin layer/polyester layer/heat-resistant resin layer, and the outermost heat-resistant resin layer substantially covers the mouth. A multilayer preformed product, characterized in that the multilayer preform is formed continuously from the open end of the support ring to the support ring. (2) In the multilayer preformed product according to claim 1, the shoulder portion has a seven-layer structure of polyester layer/heat-resistant resin layer/polyester layer/heat-resistant resin layer/polyester layer/heat-resistant resin layer/polyester layer. A multilayer preform, characterized in that it has. (3) In the multilayer preformed product according to claim 1 or 2, the proportion of the heat-resistant resin layer increases as it approaches the opening end, and the proportion (weight ratio) of the heat-resistant resin layer increases as it approaches the opening end. A multilayer preformed product characterized in that it is 70% or more in the sealing part, 40% or more in the screw tightening part, and 30% or more in the head pressure applying part. (4) The multilayer preformed product according to any one of claims 1 to 3, wherein the heat-resistant resin layer is not substantially formed on the body portion and the bottom portion. . (5) The multilayer preformed product according to any one of claims 1 to 4, wherein the polyester resin is polyethylene terephthalate. (6) The multilayer preformed product according to any one of claims 1 to 5, wherein the heat-resistant resin is a mixture of polyarylate and polyethylene terephthalate.