JPH08309833A - Manufacture of polyester hollow vessel with transparency - Google Patents

Abstract

PURPOSE: To obtain a polyester hollow vessel having excellent transparency by specifying a molten resin temperature and a cylinder molten resin staying time and kneading and injection molding specific aromatic polyester intimate mixture. CONSTITUTION: An aromatic polyester intimate mixture contains two types of polyethylene terephthalate and polyethylene naphthalene dicarboxylate polymer. The intimate mixture of the state for satisfying at least one of formulae I and II is kneaded and injection molded under the conditions of melting resin temperature of 260 to 340 deg.C and cylinder molten resin staying time of 100 to 220 seconds by using an injection molding machine. [η]A in the formula is the intrinsic viscosity of the polyethylene terephthalate, [η]A is the intrinsic viscosity of polyethylene naphthalenedicarboxylate polymer, Tm A is the melting point of the polyethylene terephthalate, and Tm B is the melting point of the polyethylene naphthalenedicarboxylate polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent polyester blend hollow container and a method for producing the same.
More specifically, 2 of polyethylene terephthalate and polyethylene naphthalene dicarboxylate type polymer
The present invention relates to a polyester hollow container having excellent transparency, which is obtained by uniformly mixing a mixture of various aromatic polyesters by an injection molding machine, and then performing injection molding and, if necessary, orientation blow treatment, and a method for producing the same.

[0002]

2. Description of the Related Art Polyethylene terephthalate has come to be widely used as a container for food and cosmetics because of its excellent mechanical properties and chemical properties.

Among polyesters, polyethylene terephthalate is mentioned as a material generally used for hollow moldings, that is, bottles, and is used for juices, soft drinks and the like. However, in recent years, in order to cope with the quality required for the material, that is, the filling method of the contents is sterilization, high temperature, etc. Materials having excellent barrier properties and transparency are desired.

On the other hand, polyethylene naphthalene dicarboxylate (hereinafter sometimes abbreviated as polyethylene naphthalate) is more heat resistant than polyethylene terephthalate,
It is known as a material with excellent gas barrier properties, and its application to bottles and films is being investigated. For example, Japanese Unexamined Patent Publication No. 52-45466 describes that polyethylene terephthalate alone is a hollow container having excellent heat resistance and gas barrier properties.

Although polyethylene terephthalate is a transparent plastic, further improvement in heat resistance and gas barrier properties is desired. For example, by blending polyethylene terephthalate with polyethylene naphthalate, heat resistance, Obtaining a packaging material having excellent gas barrier properties is disclosed in JP-A-50-122549, JP-A-2-276855, and JP-A-2-2.
It is shown in Japanese Patent No. 74757.

[0006]

However, in any of these cases, since polyethylene terephthalate and polyethylene naphthalate have poor compatibility with each other, the means for melt kneading both using an extruder or the like is A pelletized polyester hollow container is produced by two plasticizing steps in which pellets are granulated by blending, and then a preform (referred to as a preform) for the hollow container is injection-molded.

On the other hand, the method of obtaining a molded product by blending polyethylene terephthalate and polyethylene naphthalate with an injection molding machine has the advantage that the kneading and extrusion step can be omitted and the blending ratio can be easily changed. With.

However, by simply blending polyethylene terephthalate and polyethylene naphthalate in an injection molding machine, a normal molding cycle (for example, L / D =
With a molding machine of about 20 and a residence time of about 30 seconds for a molding cycle, the blended molded product exhibits a milky white color, and transparency cannot be obtained.

[0009]

Means for Solving the Problems Accordingly, the present inventors have:
In order to solve such a problem, as a result of intensive studies, polyethylene terephthalate and polyethylene naphthalate prepared so as to have transparency have specific intrinsic viscosity and melting point are blended under specific injection molding conditions. By doing so, they have found that a polyester hollow container having transparency can be obtained, and have reached the present invention.

[0010]

OBJECTS OF THE INVENTION The object of the present invention is to solve the problem of opacity associated with the mixing of two aromatic polyesters as described above. And according to this invention, the polyester hollow container excellent in transparency and its manufacturing method are provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a mixture of two aromatic polyesters of (A) polyethylene terephthalate and (B) polyethylene naphthalene dicarboxylate type polymer, represented by the following formulas (1) and (2): It is characterized in that the mixture, which satisfies at least one of the conditions, is kneaded and injection-molded by using an injection molding machine at a molten resin temperature of 260 to 340 ° C. and a cylinder molten resin residence time of 100 to 220 seconds. It is a method for producing a transparent polyester hollow container. However,

[0012]

[Equation 3] 0.53 [η] _A −0.03 <[η] _B <0.53 [η] _A +0.16 (1)

[0013]

[ _Equation 4] −5 <T _mA −T _mB <5 (2) (where [η] _A is the intrinsic viscosity of polyethylene terephthalate, [η] _B is the intrinsic viscosity of the polyethylene naphthalene dicarboxylate polymer, T _mA represents the melting point of polyethylene terephthalate, and T _mB represents the melting point of the polyethylene naphthalene dicarboxylate polymer.) The present invention will be described.

The term "polyethylene terephthalate" as used in the present invention means that ethylene terephthalate units are 85 mol% or more,
A polymer composed of a substantially linear polyester, preferably composed of a polyethylene terephthalate homopolymer. Examples of the component that can be copolymerized at a ratio of 15 mol% or less with respect to the ethylene terephthalate unit include, for example, diethylene glycol, alkylene glycols excluding ethylene glycol having 1 to 10 carbon atoms, cyclobutanediol, hexahydro-P-xylene glycol and the function thereof. Alcohols such as organic derivatives, or aromatic dicarboxylic acids such as isophthalic acid, P-diphenyl-4,4'-dicarboxylic acid, hexahydroterephthalic acid, 1,5-naphthalenedicarboxylic acid, sulfoisophthalic acid, and the like And functional derivatives of dicarboxylic acid of the above.

The polyethylene naphthalate-based polymer referred to in the present invention has a constitutional unit of ethylene-2,6-
The main component consisting of naphthalene dicarboxylate units,
If necessary, copolymerization is carried out using a dibasic acid or dihydric alcohol as the third component of 15 mol% or less, and the melting point is adjusted to a predetermined temperature. That is, when polycondensing 2,6-naphthalenedicarboxylic acid or a functional derivative thereof and ethylene glycol or a functional derivative thereof in the presence of a catalyst, as a third component of 15 mol% or less, preferably 10 mol% or less, For example, dicarboxylic acids such as oxalic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,7-dicarboxylic acid, succinic acid and diphenyl ether dicarboxylic acid, or alkyl esters provided therewith, P-oxybenzoic acid , A polymer obtained by copolymerizing an oxycarboxylic acid such as P-oxyethoxybenzoic acid or an alkyl ester provided therewith, or a compound such as a dihydric alcohol such as propylene glycol and trimethylene glycol, or benzoic acid, benzoylbenzoic acid,
Substantially modified by a monofunctional compound such as benzyloxybenzoic acid or methoxyalkylene glycol, which is modified with a polymer having a terminal hydroxyl group and / or carboxyl group blocked or a polyfunctional ester-forming compound such as glycerin or pentaerythritol in a very small amount. Examples thereof include linear copolymers.

The "mixing ratio" of (A) polyethylene terephthalate and (B) polyethylene naphthalate polymer is not particularly limited, but (A) / (B) is 90/10 to 10/90 by weight. Preferably 30/70 to 70
/ 30 is particularly preferable.

The manufacturing method is such that (A) and (B) set to the above mixing ratio are dried in advance with a hot air dryer or the like,
Preferably, (A) and (B) are mixed in a state where the water content of each pellet is set to 0.004% or less, and the pellet mixture is formed into a preform by an injection molding machine or the like.

As a condition for manufacturing the preform, the temperature of the resin is set to be in the range of 260 to 340 ° C. by heating the barrel or the hot runner of the injection molding machine or the like. Here, the resin temperature refers to a temperature at which the resin injected from the tip of a nozzle of an injection molding machine or the like is immediately measured with, for example, a thermocouple thermometer. In the resin temperature range of 260 to 340 ° C., it is possible to injection-mold mixed pellets of polyethylene terephthalate and polyethylene naphthalate polymer. And preferably 290
To 310 ° C., more preferably 295
It is a temperature range of ˜305 ° C. However, if the temperature is lower than 260 ° C., the torque load of the injection molding machine or the like is large and molding becomes difficult, and if the temperature is 340 ° C. or higher, the molecular weight of the obtained molded product is largely reduced, and thus the hollow molding performed after the production of the preformed body is performed. Blow molding for body manufacture becomes difficult.

The residence time is the time when the resin is melted in the molding machine, specifically, the time when the resin is melted and held in the cylinder and the hot runner in the molding machine. . Residence time is the cycle time of injection molding machine, etc., measuring stroke (screw back amount)
Is set to a range of 100 to 220 seconds. If the residence time is t, then t
Is given by the following equation (3).

[0020]

[Equation 5] t = W · s / P (3) where W: weight of resin melted in cylinder and hot runner of injection molding machine (g) S: time of one molding cycle (second) P : Weight of molded product in one shot of molding (g) Under conditions where either one or both of the above formulas (1) and (2) are satisfied and the resin temperature is set in the range of 260 to 340 ° C. 100 to 220 hours
By setting it in the range of seconds, a preform having good transparency can be produced by using a mixed pellet of polyethylene terephthalate and polyethylene naphthalate polymer using an injection molding machine or the like.

However, even under the above conditions, the residence time is 10
If the time is less than 0 seconds, it becomes difficult to obtain transparency of the preform. On the other hand, when the residence time is 220 seconds or more, the transparency of the preform is obtained, but the molding cycle becomes long, the productivity of the preform is reduced, and the preform is retained for a long time. As a result, the physical properties such as a decrease in the molecular weight are deteriorated, and it becomes difficult to perform blow molding for producing the hollow molded article after the production of the preformed article.

Next, when the hollow molded body is, for example, a bottle, a method of producing the hollow molded body by blow molding the above-mentioned preformed body with a blow molding machine or the like can be adopted. Also, a method of producing a preformed body from the blended pellets and continuously blowing it into a blowing die to produce a hollow formed body can be adopted.

[0023]

The present invention will be specifically described with reference to the following examples. The polymer intrinsic viscosity, SDC measurement, resin temperature measurement, residence time measurement and haze measurement were carried out with the following devices and conditions.

1. Intrinsic viscosity [η] (1) Polyethylene terephthalate [η] Determined from the solution viscosity obtained by measurement in an orthochlorophenol solvent at 35 ° C. (2) It was determined from the solution viscosity obtained by measurement at 35 ° C. in a 3: 2 mixed solvent of [η] phenol of polyethylene naphthalate polymer and 1,1,2,2-tetrachloroethane.

2. Melting point DuPont USA 910 scanning calorimeter (Differential S
canning Calorimeter) and 2100 thermal analyzer (thermal
Analyzer). The sample amount was 10 mg, the temperature rising rate was 5 ° C./min, and the melting point was determined from the melting point peak.

3. Molding of preformed body Using an injection molding machine (M-100DM, manufactured by Meiki Seisakusho Co., Ltd.), the outer shape is 30 mm, the length is 155 mm, and the wall thickness is 4.0 mm.
A preform having a weight of 55 g is changed in a cylinder and a hot runner at 255 to 350 ° C. in a molding cycle of 30 to 120 seconds, an injection pressure is 30 kg / cm ² , and a mold temperature is 1.
It was molded under the condition of 5 ° C.

4. Molding of Hollow Molded Body
nati Milacron) RHB-L was used to mold a 1500 ml bottle by blow molding with an infrared heater output of 50% and a heating time of 110 seconds.

5. Measurement of Resin Temperature The molten resin injected from the tip of the nozzle of the injection molding machine was measured with a thermocouple thermometer.

6. Residence Time It was obtained from the above-mentioned weight melted in the injection molding machine, the weight of the molded product for one shot, and the molding cycle time using the formula (3).

7. Transparency measurement 5 cm x 5 c on the body of the molded bottle (wall thickness about 0.4 mm)
MOD made by Nippon Denshoku Industries Co., Ltd.
Haze was measured with an EL101DP haze meter.

[Examples 1 to 3 and Comparative Examples 1 to 5] Blends of polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) polymer modified with an ethylene terephthalate component as shown in Table 1 were used, and the blend ratio was 7: 3 constant, the resin temperature is 300 ° C. under the condition that one or both of the formula (1) and the formula (2) are satisfied,
Molding conditions in which the residence time was 170 seconds were set to Examples 1 to 3, whereas conditions in which the formulas (1) and (2) were not satisfied at the same resin temperature and residence time were set as Comparative Example 1, and the formula ( The conditions for satisfying both 1) and the formula (2) and out of the temperature range of 260 to 340 ° C. or the residence time range of 100 to 220 seconds are Comparative Examples 2 to 5, and the haze of the bottle body is determined. The characteristics were compared.

[0032]

[Table 1]

As can be seen from Table 1, Example 1 has the lowest haze and the best transparency. Also in Examples 2 and 3, the haze is 5% or less, and the transparency is good. On the other hand, in Comparative Example 1, the haze was 9% and the transparency was inferior, and in Comparative Example 2, the torque of the injection molding machine increased significantly and molding was impossible. Further, in Comparative Example 3, the molecular weight of the molded product was lowered, the glow molding was difficult, and the hollow molded product could not be obtained. In Comparative Example 4, the haze was 10% and the transparency was poor. Furthermore, Comparative Example 5 was considered to be inferior in productivity because it was a hollow molded body which was difficult to blow mold and had a significantly uneven thickness at the bottom, and the injection molding cycle was long.

As described above, preforming obtained by mixing and kneading a pellet mixture of polyethylene terephthalate and polyethylene naphthalate polymer under various conditions as shown in Examples 1 to 3 by an injection molding machine. It has been found that the blow-molded polyester hollow container has excellent transparency.

Claims (2)

[Claims] 1. A mixture of two aromatic polyesters of (A) polyethylene terephthalate and (B) polyethylene naphthalene dicarboxylate polymer,
The mixture, which satisfies at least one of the following formulas (1) and (2), is melted using an injection molding machine at a molten resin temperature of 260 to 340 ° C. and a cylinder molten resin residence time of 10:
A method for producing a polyester hollow container having transparency, which comprises kneading and injection molding under conditions of 0 to 220 seconds. [Equation 1] 0.53 [η] _A −0.03 <[η] _B <0.53 [η] _A +0.16 (1) [Equation 2] −5 <T _mA −T _mB <5 (2) (where [η] _A is the intrinsic viscosity of polyethylene terephthalate, [η] _B is the intrinsic viscosity of polyethylene naphthalene dicarboxylate polymer, T _mA is the melting point (° C.) of polyethylene terephthalate, and T _mB is polyethylene naphthalene. The melting points of dicarboxylate polymers are shown.) 2. Polyethylene terephthalate 90 to 10
A polyester hollow container having a transparency, in which the haze of the body part is 5% or less, which is a hollow molded product composed of 10 parts by weight to 10 parts by weight of a polyethylene naphthalene dicarboxylate polymer.