JPH06255645A - Bottle of regenerated polyethylene terephthalate resin - Google Patents

Abstract

PURPOSE:To provide a bottle of high transparency and mechanical strength using regenerated polyethylene terephthalate resin. CONSTITUTION:A regerenated PET resin bottle 4 is made by a solid phase polymerization of flake members and biaxially stretched a regenerated PET resin 1 which is formed in pellet. It is also possible that the bottle 4 is made by placing the regenerated PET resin 1 as an internal layer and a new PET resin 2 as an external layer in lamination, and then biaxially stretched. It is further possible that the bottle is obtained by mixing the regenerated PET resin 1 and the new PET resin 2 and then biaxially stretchd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottle obtained by biaxially stretching a polyethylene terephthalate resin reclaimed from a molded product such as a polyethylene terephthalate resin bottle used for food and drink containers.

[0002]

2. Description of the Related Art A bottle formed by biaxially stretching a polyethylene terephthalate resin (hereinafter sometimes abbreviated as PET resin) is superior in mechanical strength, transparency and gas barrier property to other plastic containers. Further, it is not only excellent in mechanical strength as compared with a glass container but also light in weight, so that it is favorably used for food and drink containers and the like.

However, since the PET resin bottle is bulky and does not easily weather, it may cause pollution when used as a food and drink container and then dumped improperly. It is possible to incinerate it after collecting it, but PET
Regarding the so-called thermal cycle in which the resin is incinerated and the thermal energy is recovered, a consensus as an appropriate treatment method is not necessarily obtained at present. Therefore, it has been considered to recover the PET resin bottle and regenerate the PET resin to use it as a raw material for a molded product.

Conventionally, as the PET resin regenerated from the PET resin bottle, for example, a flake material obtained by forming a recovered PET resin bottle into a flake shape, or a pellet obtained by pelletizing the flake material with an extruder. Known is a crushed material, or a crushed material obtained by crushing the above flake material with a crusher mixer and granulating it with frictional heat. The recycled PET resin is used, for example, as a resin for injection molding together with a new PET resin. As shown in FIG. 1, the recycled PET resin 1 is used as an inner layer, and a new PET resin 2 is laminated as an outer layer sandwiching the inner layer. Three
Is manufactured. This multi-layer preform 3 is molded into a remolded product 4 such as a bottle shown in phantom in FIG. 1 by a normal biaxial stretch blow molding method.

However, in the multi-layer preform 3 shown in FIG. 1, a regenerated PET which is simply molded into flakes from the recovered PET resin bottle and is not solid-phase polymerized.
When the resin 1 is used, the intrinsic viscosity (IV value) of the obtained bottle tends to decrease as the usage amount increases, as shown in Table 1 below.

When the IV value decreases, the haze increases as shown in Table 1, and the damage rate increases.

[0007]

[Table 1]

The increase in haze of the bottles shown in Table 1 indicates a decrease in transparency, and the increase in the breakage rate indicates a decrease in drop strength. In addition, the above-mentioned damage rate is 1 drop from a height of 1.8 m after dropping 3 times from a height of 1.2 m.
Shows the rate of bottle breakage when repeated. Further, the relationship between the usage amount of the recycled PET resin 1 shown in Table 1 and each characteristic of the bottle is graphed and shown in FIGS. 3 to 5.

As is apparent from Table 1, conventional recycled PE
The bottle obtained by biaxially stretching the T resin has a disadvantage that the characteristics of the PET resin such as transparency and mechanical strength cannot be sufficiently obtained.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate such inconveniences and provide a bottle which uses a recycled polyethylene terephthalate resin and has excellent transparency and mechanical strength.

[0011]

In order to achieve the above object, the bottle of recycled polyethylene terephthalate resin of the present invention is characterized by biaxially stretching a recycled polyethylene terephthalate resin obtained by solid-state polymerization of a flake material. And

As the flake material, for example, a flake material formed by collecting PET resin bottles used for food and drink containers after use and forming them into flakes can be used.

For the solid-phase polymerization of the flake material, the solid-phase polymerization method conventionally used for reducing the acetaldehyde content of a polyester resin can be used as it is. For example, the flake material of 130 to 150 can be used. After being crystallized by heating in an inert gas of ℃ for 1 to 2 hours, the crystallized PET resin is heated in an inert gas of 150 to 160 ℃ for 5 hours.
Recycled PET resin having a high IV value, which is obtained by heating for 7 hours to dry and further heating in an inert gas at 210 to 230 ° C. for 12 to 17 hours for solid-phase polymerization to polymerize and then cooling. Can be obtained in a short time and at low cost. The heating is performed by using an inert gas such as nitrogen,
Oxidation of the PET resin heated to a high temperature is prevented. In addition, the drying removes water from the crystallized PET resin and prevents hydrolysis of the PET resin when heated to a high temperature for solid phase polymerization.

The recycled polyethylene terephthalate resin bottle of the present invention has a constitution in which the recycled polyethylene terephthalate resin is placed in the inner layer and new polyethylene terephthalate resin is placed in both outer layers of these layers and laminated.
Biaxially stretched.

The recycled polyethylene terephthalate resin bottle of the present invention is formed by mixing a recycled polyethylene terephthalate resin obtained by solid-phase polymerization of the flake material and a new polyethylene terephthalate resin and biaxially stretching them.

The recycled polyethylene terephthalate resin bottle of the present invention is formed by molding the recycled polyethylene terephthalate resin into a pellet material and biaxially stretching the pellet material.

[0017]

According to the present invention, a recycled PET resin having a high IV value obtained by solid-phase polymerization of a flake material is biaxially stretched to obtain a bottle excellent in transparency and mechanical strength.

According to the present invention, the recycled PET resin obtained by solid-phase polymerizing the flake material is placed in the inner layer, and the new polyethylene terephthalate resin is placed in the outer layer, laminated and biaxially stretched to obtain the recycled PET resin. Since it does not directly contact the contents, a bottle suitable for food and drink containers can be obtained.

According to the present invention, since the recycled PET resin having a high IV value obtained by solid-phase polymerization of the flake material is used, the recycled PET resin and new PET are mixed and biaxially stretched. A bottle having excellent transparency and mechanical strength can be obtained.

Further, according to the present invention, the flowability is improved by molding the recycled PET resin obtained by solid-phase polymerizing the flake material into a pellet material.

[0021]

EXAMPLES The recycled PET resin bottle of the present invention will be described in more detail with reference to the accompanying drawings.
FIG. 1 is an explanatory cross-sectional view showing the structure of the recycled PET resin bottle of this embodiment, and FIG. 2 is a schematic explanatory view showing the manufacturing process of the recycled PET resin.

As shown in FIG. 1, recycled PET of this embodiment.
In the resin bottle 4, recycled PET resin 1 obtained by solid-state polymerization of flake material and further molded into pellet material is placed in the inner layer, and new PET resin 2 is placed in the outer layer so as to sandwich the recycled PET resin 1 therebetween. The laminated multi-layer preform 3
It is molded by biaxial stretching blow. Recycled PET of this embodiment
Since the new PET resin 2 is placed in the outer layer of the resin bottle 4 and the recycled PET resin 1 does not come into contact with the contents, it can also be used as a container for food and drink, etc. that are sensitive to flavor. You can

The recycled PET resin 1 used in the recycled PET resin bottle 4 of the present embodiment is obtained as follows.

First, the PET bottles for soy sauce thus recovered were formed into flakes to produce flaky flakes having a maximum length of about 10 mm. The formation of the flake material was performed until the flake material completely passed through a screen having an opening of 8 mm so that an excessively large flake material was not mixed.

When a content having a strong smell like soy sauce is filled for a long time as compared with a general drink, the smell component becomes PE.
It is known that it will be transferred to T bottles, and if such a bottle is made into flakes as described above, the odor adsorbed in the PET bottle will remain in the flake material, and it is expected that its use will be restricted. To be done. Therefore, the soy sauce odor adhering to the PET bottle for soy sauce recovered by washing the flake material with a hot alkaline solution was deodorized.
The flake material obtained as described above has a density of 0.648 (d
It had an IV value of 1 / g).

Next, the flake material was replaced with recycled PE shown in FIG.
The solid-state polymerization was carried out by charging the T-resin manufacturing apparatus 21.

In the apparatus 21 for producing recycled PET resin, the flake material is put into the raw material storage tank 23a from the hopper 22, and continuously passes from the preheating tank 24 to the heating tank 25 and the cooling tank 26 via the raw material storage tank 23b. The recycled PET resin supplied and produced is continuously discharged from the discharging rotary valve 31.

First, from the hopper 22 to the raw material storage tank 23a
The flake material charged in the above is continuously supplied to the raw material storage tank 23b by the valve 27. At this time, the raw material storage tanks 23a and 23b themselves are not provided with a structure for heating the supplied flake material, but since they receive radiant heat from the preheating tank 4 provided below, they have a flaky shape with a maximum length of about 10 mm. The flake materials tend to be heated and tend to fuse together. Therefore, in the raw material storage tanks 23a and 23b,
The stirring device 32 is provided with a stirring blade 32a that gently rotates so as to stir the flake materials so that they are not fused to each other.

Next, the flake material is used as a raw material storage tank 23.
b and the preheating tank 24 so as not to be fused to each other,
The raw material storage tank 23b is forcibly sent to the preheating tank 24 by the rotary valve 28.

The preheating tank 24 is taken out from the nitrogen gas discharge port 25b of the heating tank 25 and is heated by the heating means 36b.
The nitrogen gas reheated to 0 ° C. is circulated by the compressor 35b to heat the introduced flake material. The flake material charged into the preheating tank 24 is heated by the nitrogen gas while passing through the preheating tank 24, crystallized in the first 2 hours, and the water content contained in the next 5 hours becomes 30 ppm or less. It is dried so that it is sent to the rotary valve 29.

In the preheating tank 24, stirring is provided with stirring blades 32a so that the flake materials are not fused to each other as described above, and that the nitrogen gas blown in can flow between the flake materials. It is agitated by the device 32. The stirring device 32 is rotated at an extremely low speed so as not to hinder the flow of the flake material from the preheating tank 24 toward the rotary valve 29. Further, the nitrogen gas is blown from the nitrogen gas blowing port 24a provided at the bottom of the preheating tank 24, so that the preheating tank 24
The flake materials crystallized inside do not adhere to each other and block the inlet of the rotary valve 29. still,
The nitrogen gas heats the flake material in the preheating tank 24 and then is discharged from the nitrogen gas discharge port 24b.

Next, the crystallized flake material is compulsorily heated by the rotary valve 29 from the preheating tank 24 so as not to be fused to each other between the preheating tank 24 and the heating tank 25. Sent to.

In the heating tank 25, the nitrogen gas supplied from the nitrogen gas supply source 34 and heated to 220 ° C. by the heating means 36a is circulated by the compressor 35a, and the charged crystallized flake material is heated. It is supposed to do. The crystallized flake material charged in the heating tank 25 is heated by the nitrogen gas while passing through the heating tank 25 for 10 hours, polymerized by solid phase polymerization, and sent to the rotary valve 30. To be

In the heating tank 25, the crystallized flake material is stirred by the stirring device 32 having the stirring blades 32a as in the preheating tank 24. Stirrer 32
Is rotated at an extremely low speed so as not to disturb the flow of the crystallized flake material from the heating tank 25 toward the rotary valve 30. Further, the nitrogen gas is used in the heating tank 2
The flake material solid-phase-polymerized in the heating tank 25 is prevented from fusing with each other by being blown from the nitrogen gas blowing port 25a provided at the bottom of the rotary valve 30. . The nitrogen gas heats the crystallized flake material in the heating tank 25, is discharged from the nitrogen gas discharge port 25b, and is reheated by the heating means 36b as described above, and then the preheating tank 24 is heated. It is used for heating.

Next, the solid-state polymerized flake material is
The heating tank 25 is forcibly fed into the cooling tank 26 by the rotary valve 30 so that the heating tank 25 and the cooling tank 26 do not fuse with each other.

In the cooling tank 26, the gas cooled to 40 ° C. by the cooling means 39 is circulated by the compressor 38, and about 6 parts of the solid-phase polymerized flake material is charged.
The recycled PET resin is cooled to 0 ° C. and sent to the rotary valve 31.

In the cooling tank 26, the solid-phase polymerized flake material is stirred by the stirring device 32 having the stirring blades 32a as in the preheating tank 24. Stirrer 3
2 does not hinder the flow of the solid-phase polymerized flake material from the cooling tank 26 toward the rotary valve 31,
It is rotating very slowly. Further, the cooling gas is blown from a cooling gas blowing port 26a provided at the bottom of the cooling tank 26, so that the regenerated PET resins cooled to the temperature in the cooling tank 26 are fused to each other and the rotary valve The entrance of 31 is not blocked. The cooling gas cools the solid-phase polymerized flake material in the cooling tank 26, is then discharged from the cooling gas discharge port 26b, and is circulated to the cooling means 39 by the compressor 38.

Then, the rotary PET valve 3 for discharging the recycled PET resin from the cooling tank 26 so as not to be fused with each other.
It is forcibly discharged by 1.

The flake material obtained by solid phase polymerization as described above is then pelletized by an extruder to obtain a pellet material. Since the flake material has better fluidity by being pelletized, when it is fed to an extrusion molding machine or the like for molding the multi-layer preform 3, it is not clogged with a hopper, a valve, a screw, etc. It will be easier.

In this example, in the multilayer preform 3 shown in FIG. 1, the flake material was solid-phase polymerized as described above,
Next, the regenerated PET resin 1 obtained by pelletizing is placed in the inner layer, and the amount of the recycled PET resin 1 used is 10
4 kinds of recycled PET resin bottles 4
Was manufactured. IV of the obtained recycled PET resin bottle 4
Table 2 shows the values, haze, and breakage rate. Also, for comparison, a preform 3 made only of new PET resin
Of a PET resin bottle obtained by biaxially stretching
Table 2 shows the V value, cloudiness (haze), and breakage rate.

[0041]

[Table 2]

From Table 2, it is clear that the recycled PET resin bottle 4 of this example has the same transparency and mechanical strength as the PET resin bottle obtained only from the new PET resin. In Table 2, the damage rate is
1.8m after dropping from 1.2m height 3 times
The breakage rate of the bottle when dropped once from the height is shown.

Further, the IV value of the recycled PET resin bottle 4 of this example is PE obtained only from the new PET resin.
It is higher than that of T resin bottles, and tends to increase as the amount of recycled PET resin 1 used increases. Therefore, recycled PE obtained by solid-phase polymerization of the flake material
According to the T resin, even if it is mixed with a new PET resin at an arbitrary ratio, or even if the recycled PET resin is used alone,
It is clear that a bottle made of recycled PET resin having a higher IV value can be obtained than a bottle made of PET resin obtained only from new PET resin.

In this embodiment, in order to improve the moldability of the recycled PET resin bottle 4, the solid-state polymerized flake material is further molded into a pellet material for use. However, the flake material is used as it is. May be used.

[0045]

As is apparent from the above, according to the present invention, the recycled PET resin is biaxially stretched by solid-phase polymerizing the flake material, whereby the recycled PET excellent in transparency and mechanical strength is obtained. A resin bottle can be obtained.

Further, according to the present invention, the recycled PET resin obtained by solid-phase polymerization of the flake material is arranged in the inner layer, and the new polyethylene terephthalate resin is arranged in the outer layer and laminated, and biaxially stretched to obtain the recycled PET resin. Since the PET resin does not come into direct contact with the contents, it is possible to obtain a bottle suitable for a food and drink container with a sharp flavor.

Further, according to the present invention, since the recycled PET resin obtained by solid-phase polymerizing the flake material is used, the recycled PE resin is used.
A bottle excellent in transparency and mechanical strength can also be obtained by mixing T resin and new PET and biaxially stretching.

Further, according to the present invention, the recycled PET resin obtained by solid-phase polymerization of the flake material is molded into a pellet material so that the flowability is improved, so that clogging of the hopper, the valve and the like can be prevented. It is possible to easily form a preform or the like.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view of a recycled polyethylene terephthalate resin bottle according to the present invention.

FIG. 2 is a schematic diagram showing a configuration example of a solid-state polymerization apparatus for recycled polyethylene terephthalate resin.

FIG. 3 is a graph showing the relationship between the amount of recycled polyethylene terephthalate resin used in a conventional bottle made of recycled polyethylene terephthalate resin and the intrinsic viscosity of the bottle.

FIG. 4 is a graph showing the relationship between the amount of recycled polyethylene terephthalate resin used in a conventional bottle made of recycled polyethylene terephthalate resin and the amount of fogging generated in the bottle.

FIG. 5 is a graph showing the relationship between the amount of recycled polyethylene terephthalate resin used in a conventional bottle made of recycled polyethylene terephthalate resin and the breakage rate of the bottle.

[Explanation of symbols]

 1 ... Recycled polyethylene terephthalate resin, 4 ... Recycled polyethylene terephthalate resin bottle.

Claims (4)

[Claims] 1. A bottle made of recycled polyethylene terephthalate resin, which is obtained by biaxially stretching a recycled polyethylene terephthalate resin obtained by solid-state polymerization of a flake material. 2. The regenerated polyethylene according to claim 1, wherein the regenerated polyethylene terephthalate resin is disposed in an inner layer, and new polyethylene terephthalate resin is disposed in both outer layers, laminated and biaxially stretched. Bottle made of terephthalate resin. 3. A bottle made of recycled polyethylene terephthalate resin according to claim 1, wherein the recycled polyethylene terephthalate resin and new polyethylene terephthalate resin are mixed and biaxially stretched. 4. The bottle made of recycled polyethylene terephthalate resin according to claim 1, wherein the recycled polyethylene terephthalate resin is molded into a pellet material and the pellet material is biaxially stretched.