JP2922973B2 - Multilayer preform made of saturated polyester resin and multilayer bottle obtained from this preform - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multilayer preform made of a saturated polyester resin and a multilayer bottle obtained from the preform. More specifically, the present invention relates to a multilayer preform in which whitening is suppressed in a bottle forming step, and The present invention relates to a multilayer bottle excellent in transparency obtained by molding the preform.

Technical Background of the Invention Conventionally, glass has been widely used as a material for containers such as seasonings, oils, juices, carbonated drinks, beer, sake, cosmetics, and detergents. However, since the production cost of the glass container is high, a method of collecting an empty container after normal use and circulating and reusing the container has been adopted. Further, since the glass container is heavy, the transportation cost is increased, and the glass container is liable to be broken and is inconvenient to handle.

For this reason, the conversion from glass containers to various plastic containers has been rapidly progressing recently. As the plastic material, various plastics are adopted according to the kind of the filling content and the purpose of use, and among these plastic materials, saturated polyester resins such as polyethylene terephthalate have mechanical strength, heat resistance, and transparency. Because of its excellent properties and gas barrier properties, it is used as a material for containers for juices, soft drinks, carbonated drinks, seasonings, detergents, and cosmetics. Among these applications, bottles for filling juices, soft drinks and carbonated drinks, in particular, are required to be sterilized and hot-filled, thus forming heat-resistant bottles that can withstand high-temperature filling. And all of these filling bottles are required to have transparency.

By the way, in particular, a saturated polyester resin such as polyethylene terephthalate is supplied to a molding machine such as an injection molding machine to form a preform for a hollow molded body. However, there is a serious problem in that the resulting bottle is whitened and the transparency of the bottle is reduced. For this reason, bottles with reduced transparency have to be discarded, and the yield has been greatly reduced.

The present inventors have intensively studied to obtain a bottle made of a saturated polyester resin such as polyethylene terephthalate excellent in transparency and heat resistance, and found that the bottle made of a saturated polyester resin is whitened and the transparency is reduced. One is that when a preform obtained from a saturated polyester resin is blow-molded, oligomers such as cyclic trimers contained in the saturated polyester resin increase and adhere to a blow-molding mold. (Referred to as mold stains), and found that the mold stains are caused to adhere to the surface of the saturated polyester resin bottle or to form irregularities on the bottle surface. Investigations based on the above findings have revealed that the above problems can be solved by reducing the oligomer content in the saturated polyester resin.

However, a resin having a low oligomer content tends to increase the production cost, and a bottle obtained by using the resin has a new problem that the cost is high. The present inventors have further examined these points and found that the preform having a laminate structure including a general-purpose saturated polyester resin layer and a saturated polyester resin layer having a low oligomer content has the above-described problems. Have been solved at once, and it has been found that a bottle having excellent transparency and heat resistance can be obtained by using this preform, and the present invention has been completed.

Object of the Invention The present invention is intended to solve the problems in the prior art as described above, and is excellent in transparency without whitening, excellent in heat resistance, and economical and excellent in saturated polyester. It aims to provide a resin bottle.

The saturated polyester resin multilayer preform according to the present invention is formed from at least two different saturated polyester resin layers, and the oligomer content in the saturated polyester resin forming the outer peripheral surface layer of the multilayer preform is 0.5. % By weight or less.

The saturated polyester resin bottle according to the present invention is obtained by molding the above-mentioned multilayer preform with a blow mold.

The bottle thus obtained is excellent in transparency without whitening, excellent in heat resistance, and excellent in economy.

DETAILED DESCRIPTION OF THE INVENTION First, the saturated polyester resin multilayer preform according to the present invention will be specifically described.

The saturated polyester resin preform according to the present invention is formed from at least two different saturated polyester resin layers. As the saturated polyester resin forming such a resin layer, a general-purpose saturated polyester resin (a) and a low oligomer amount saturated polyester resin (b) are used.

General-purpose saturated polyester resin (a) used in the present invention
Specifically, the following saturated polyester resins are used.

Terephthalic acid or its ester-forming derivatives (eg lower alkyl esters, phenyl esters, etc.)
And polyethylene terephthalate obtained from ethylene glycol or an ester-forming derivative thereof (for example, monocarboxylic acid ester ethylene oxide). The polyethylene terephthalate may be copolymerized with less than about 20 mole% of other dicarboxylic acids or glycols. Such dicarboxylic acid components include, for example, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, and fatty acids such as adipic acid, sebacic acid, azelaic acid, and decanedicarboxylic acid. Derived from alicyclic dicarboxylic acids such as aromatic dicarboxylic acids and cyclohexanedicarboxylic acids. Glycol components include trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, aliphatic glycols such as dodecamethylene glycol, alicyclic glycols such as cyclohexanedimethanol, bisphenols, hydroquinone, 2, It is derived from aromatic diols such as 2-bis (4-β-hydroxyethoxyphenyl) propane.

Hereinafter, polyethylene terephthalate particularly preferably used in the present invention will be described. That is, preferred polyethylene terephthalate is represented by the general formula [I] The content of the ethylene terephthalate component unit (1) represented by the formula is in the range of 95.0 to 98.6 mol%, preferably 97.0 to 98.5 mol%, particularly preferably 97.3 to 98.3 mol%, and the general formula [II] The content of the dioxyethylene terephthalate component unit (2) represented by the formula is 1.4 to 5.0 mol%, preferably 1.5 to 3.0 mol%.
Mol%, particularly preferably in the range from 1.7 to 2.7 mol%.

Such preferred polyethylene terephthalate is
The ethylene terephthalate component unit (1) represented by the general formula [I] and the dioxyethylene terephthalate component unit (2) represented by the general formula [II] are randomly arranged to form an ester bond. To form polyester. The fact that the polyethylene terephthalate is substantially linear is confirmed by the fact that the polyethylene terephthalate dissolves in o-chlorophenol.

The o of such preferred polyethylene terephthalate
-Intrinsic viscosity [η] measured in chlorophenol at 25 ° C
Is in the range of 0.60 to 0.90 dl / g, preferably 0.70 to 0.87 dl / g, particularly preferably 0.72 to 0.85 dl / g.

Further, such a preferred polyethylene terephthalate has a temperature-increasing crystallization temperature (Tcc ₁ ) of 140 ° C. or higher when the temperature is raised at a rate of 10 ° C./min by a differential scanning calorimeter (DSC).
It is preferably in the range from 150 to 185 ° C, particularly preferably from 168 to 180 ° C. Also, the preferred heating crystallization temperature of polyethylene terephthalate (Tcc _1), in the relationship between the intrinsic viscosity [eta _1], the following equation _{52.6 [η 1] + 119.0 ≦} Tcc 1 ≦ 67.5 [η 1] +133. 5, more preferably 67.5 [η ₁ ] + 122.5 ≦ Tcc ₁ ≦ 67.5 [η ₁ ] +128.5.

Note that the above-mentioned elevated crystallization temperature (Tcc ₁ ) is measured by the following method. That is, DSC manufactured by PerkinElmer
Using a type-2 differential scanning calorimeter at about 140 ° C under a pressure of about 5 mmHg, a sample of about 10 mmg from the center of a saturated polyester chip dried for about 5 hours or more under a nitrogen atmosphere in a liquid aluminum pan. Measured by enclosing with. The measurement conditions were as follows: first, the temperature was rapidly raised from room temperature, melted and held at 290 ° C for 10 minutes, then rapidly cooled to room temperature, and then the peak temperature of the exothermic peak detected when the temperature was raised at a rate of 10 ° C / min. Ask for.

Next, a low-oligomer saturated polyester resin (b)
Will be described.

This saturated polyester resin (b) is mixed with terephthalic acid or an ester-forming derivative thereof with ethylene glycol under conditions such that the oligomer content does not exceed 0.5% by weight, for example, under conditions such as prolonging the solid phase polymerization time. Alternatively, it can be produced by reacting with an ester-forming derivative thereof. Further, the saturated polyester resin (b) is the same as the above-mentioned saturated polyester resin (a).
To a process for reducing the oligomer content or a process for suppressing an increase in the oligomer content.

The multilayer preform made of a saturated polyester resin according to the present invention first comprises a saturated polyester resin (a) as described above.
And (b) are laminated. And the bottle which concerns on this invention is obtained by shape | molding this multilayer preform with a blow mold.

The multilayer preform is obtained by supplying a saturated polyester resin (a) and (b) to a molding machine such as an injection molding machine, an extrusion molding machine, a compression molding machine, and a hollow molding machine. During the formation of the multilayer preform, a resin raw material is supplied so that the outer peripheral surface layer of the multilayer preform is formed of a low oligomer amount saturated polyester resin (b). In the blow molding in the next step, the outer peripheral surface layer of the preform becomes a layer on the side in contact with the blow mold.

Further, the saturated polyester resins (a) and (b) for forming a preform may contain a stabilizer, an antistatic agent, an inorganic filler and the like.

When forming a multilayer preform, saturated polyester (a)
It is preferable to minimize the mechanical shear applied to (b) and (b). In order to minimize the mechanical shear applied to the saturated polyesters (a) and (b) in the heat-melted state, the following method may be used.

For example, when supplying the saturated polyester resin (a) and (b) to a molding machine such as an injection molding machine, the resin was heated in advance and supplied to the molding machine in a molten state, or the resin was supplied to the molding machine. After that, before reaching the compression part of the molding machine, the resin is heated sufficiently, such as by increasing the heating set temperature of the molding machine, and the resin is almost completely melted before reaching the compression part of the molding machine, What is necessary is just to make it reach | attain the compression part of a molding machine in this state, and shape it in a desired shape. This way,
Since the resin has been sufficiently melted by the time it reaches the compression section of the molding machine, it has a low viscosity and can reduce mechanical shear in the compression section.

In the multilayer preform obtained in this way,
The oligomer content in the low-oligomer content saturated polyester resin (b) forming the preform outer peripheral surface layer is 0.5
%, Preferably not more than 0.4% by weight.

This oligomer content is measured as follows, for example, when the saturated polyester resin is polyethylene terephthalate.

That is, a predetermined amount of polyethylene terephthalate is o-
After dissolving in chlorophenol, reprecipitating with tetrahydrofuran and filtering to remove linear polyethylene terephthalate, then supplying the obtained filtrate to liquid chromatography (LC7A, manufactured by Shimadzu Corporation) to be contained in polyethylene terephthalate The amount of oligomer (cyclic trimer) is determined, and this value is divided by the amount of polyethylene terephthalate used in the measurement to obtain the amount of oligomer (% by weight) contained in polyethylene terephthalate.

In the multilayer preform as described above, the thickness of the layer made of the low oligomer amount saturated polyester resin (b) is preferably 0.2 to 2 mm.

The multilayer preform thus obtained is blow molded in a blow mold at a blow mold temperature of 100 to 180 ° C. according to a conventional method, and then heat-set for 1 to 30 seconds, according to the present invention. A saturated polyester resin bottle having a laminated structure is obtained.

In the above-described multilayer preform made of a saturated polyester resin according to the present invention, the blow mold generated during blow molding has very little dirt, and thus the obtained bottle has high transparency and does not whiten. Moreover, since the frequency of cleaning the blow mold can be reduced, the productivity of the bottle is high. In addition, since the above-mentioned effects can be obtained using only a small amount of a low-oligomer saturated polyester resin (b) having a high production cost as compared with a general-purpose saturated polyester resin (a), excellent economical efficiency is obtained. I have.

Further, the bottle according to the present invention may be a multilayer laminated bottle comprising a saturated polyester resin (a), (b) layer and a resin layer having further excellent gas barrier properties. When manufacturing such a multilayer laminated bottle, a resin layer having excellent gas barrier properties may be formed as one layer in the preform.

Effect of the Invention The multilayer preform made of a saturated polyester according to the present invention does not cause whitening in the bottle molding process, and thus the obtained bottle is excellent not only in transparency and heat resistance but also in economical efficiency. Is also excellent.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 Polyethylene terephthalate (a) having an oligomer (cyclic trimer) content of 0.55% by weight and intrinsic viscosity [η]
Is 0.79 dl / g, the dioxyethylene terephthalate component unit is 2.30 mol%, and the oligomer content is 0.3
% Of polyethylene terephthalate (b) was dried under reduced pressure at 150 ° C. for about 16 hours, and then each barrel temperature was 270 ° C. using an ASB50T type two-layer molding machine manufactured by Nissei ASB Machine Co., Ltd. The above (a) and (b) are melted at a pressure of 70 ° C. in a preform mold cooled to 10 ° C.
A two-layer preform having a diameter of 38 mm, a body diameter of 28 mm, and a body thickness of 4.5 mm and a weight of 64 g was produced in a molding cycle of 60 seconds by injection molding at 0 kg / cm ² . The preform consists of polyethylene terephthalate (b) with an outer layer of 1 mm and an inner layer of 3.5 mm.
mm is made of polyethylene terephthalate (a). The oligomer content of the outer layer of this preform was 0.40% by weight, and the oligomer of the inner layer was 0.60% by weight. For this measurement, isolation is difficult when a preform is molded, and therefore, a resin injected from each cylinder to the outside of the mold was used. Next, a preform in which only the plug portion was crystallized in an oil bath at 160 ° C. was produced. The crystallization preform of the plug is converted into a biaxial stretch blow molding machine [COPOPLAST (CORPOP
LAST) LB010], a blowing pressure of about 20 kg / cm ² ,
Preform heating time about 60 seconds, under the condition of a stretching temperature of 105 ℃, biaxially stretched about 2.2 times in length and 3.0 times in width, and further 160
After holding in a mold having a surface temperature of 60 ° C. for 60 seconds, heat setting was performed by cooling the mold with water for 20 seconds.
A biaxially-stretched bottle having a body part having an inner volume of 1.5, six decompression panels on a body part, and a bottom part raised up was prepared.

The heating (heat setting) for 60 seconds after the stretching is for accelerating the whitening of the bottle for evaluation, and the heating (heat setting) time of 1 to 30 seconds during the production of the bottle is sufficient.

When 500 bottles were molded, all transparent bottles were obtained, and no whitened bottle was observed.

Comparative Example 1 Polyethylene terephthalate (a) used in Example 1
Molding was performed in the same manner as in Example 1 except that only the inner and outer layers were used. Although 500 bottles were formed, a bottle having a cloudy pattern occurred from the 300th bottle.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FIB29L 9:00 22:00 (56) References JP-A-2-30512 (JP, A) JP-A-58-144573 (JP, A) JP-A-56-80429 (JP, A) JP-A-56-80428 (JP, A) JP-A-61-279553 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) B29B 11/00-11/16 B29C 49/00-49/80 B65D 1/00

Claims (2)

(57) [Claims] 1. A saturated polyester resin multilayer preform formed of at least two different saturated polyester resin layers, wherein an oligomer (cyclic trimer) in the saturated polyester resin forming an outer peripheral surface layer of the multilayer polyform is provided. A) a multilayer preform made of a saturated polyester resin having a content of 0.5% by weight or less. 2. A saturated polyester resin multilayer bottle obtained by molding the saturated polyester resin multilayer preform according to claim 1 with a blow mold.