JP2741915B2 - Hollow molded body - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a hollow molded article excellent in transparency, moldability, gas barrier properties, economy and the like.

Technical Background of the Invention Conventionally, glass has been widely used as a material for containers such as seasonings, oils, beer, alcoholic beverages such as sake, soft drinks such as carbonated beverages, cosmetics, and detergents. However, although the glass container is excellent in gas barrier properties, the manufacturing cost is high, so that a method of recovering an empty container after normal use and circulating and reusing it has been adopted. However, since the glass container is heavy, there is a problem that the transportation cost is high, and the glass container is easily broken, which is inconvenient to handle.

In order to solve such problems, various plastic containers are used instead of glass containers. Various plastics are employed as the material according to the type of storage item and the purpose of use. Among these plastics, polyethylene terephthalate is used as a material for containers of seasonings, soft drinks, detergents, cosmetics, etc. because of its excellent gas barrier properties and transparency. However, in the case of beer containers or carbonated beverage containers requiring the strictest gas barrier properties among these, it is difficult to say that polyethylene terephthalate is still sufficient, and in order to use polyethylene terephthalate in these containers, The gas barrier properties had to be improved by increasing the wall thickness.

However, thick bottles, compared to thin bottles,
There is a problem that the amount of polyethylene terephthalate required to form a bottle increases, and therefore the cost of the bottle increases.

For this reason, there is an attempt to obtain a bottle excellent in gas barrier properties and economical by stretching polyethylene terephthalate at a high stretch. However, to obtain a highly drawn polyethylene terephthalate bottle,
The preform may be made thicker and stretched, but when the thickness of the preform becomes thicker, the preform is gradually cooled in the process of manufacturing the preform,
The high draw bottle obtained from this preform has a problem that it is whitened and the transparency is reduced.

On the other hand, such a problem can be solved by manufacturing a preform using polyethylene terephthalate having a high intrinsic viscosity, but polyethylene terephthalate having a high intrinsic viscosity is inferior in stretchability or moldability and also expensive. There is a problem.

JP-A-59-64624 discloses a polyalkylene isophthalate such as polyethylene isophthalate and a copolymer thereof and a molded article formed therefrom as a packaging material having good gas barrier properties against oxygen and carbon dioxide gas. ing. JP-A-59-67049
Japanese Patent Application Laid-Open Publication No. H11-157, discloses a multi-layer packaging material comprising a layer comprising the above-described polyalkylene isophthalate or a copolymer thereof and a layer comprising a polyalkylene terephthalate such as polyethylene terephthalate or a copolymer thereof, and a molded article such as a bottle comprising the same. ing.

Furthermore, a method of blending polyethylene isophthalate with polyethylene terephthalate or the like (JP-A-59-64658)
Publication).

A copolyester obtained by using isophthalic acid as a dicarboxylic acid and copolymerizing 1,3-bis (2-hydroxyethoxy) benzene together with ethylene glycol as a dihydroxy compound is disclosed in
-167817.

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, excellent in moldability and gas barrier properties, and also excellent in economical efficiency. It is intended to provide.

The hollow molded article according to the present invention is formed by esterification of terephthalic acid and a dihydroxy compound, and 85 to 99.5 mol% of the dihydroxy compound is ethylene glycol, and 0.5 to 15 mol% is cyclohexane dimethanol. Yes, it is made of a copolyester having an intrinsic viscosity [η] of 0.5 to 1.5 dl / g, and is characterized by being highly stretched to a stretching index of 130 cm or more as defined below.

DETAILED DESCRIPTION OF THE INVENTION The hollow molded article according to the present invention will be specifically described below.

First, the copolyester constituting the hollow molded article according to the present invention will be described.

Copolyester The copolyester constituting the hollow molded article according to the present invention is obtained by a co-condensation reaction between terephthalic acid and a dihydroxy compound as described below.

The dihydroxy compound used in the present invention is 85 to 99.5
Mole%, preferably 90 to 99.5 mol% is ethylene glycol, and 0.5 to 15 mol%, preferably 0.5 to 10 mol% is cyclohexane dimethanol.

When the amount of cyclohexanedimethanol is 0.5 to 15 mol%, a copolyester excellent in transparency and excellent in moldability or stretchability can be obtained.

In the present invention, when forming a copolyester, other dicarboxylic acids may be used as the dicarboxylic acid in addition to the above-mentioned terephthalic acid in an amount that does not impair the properties of the obtained copolyester, for example, 1 mol% or less. it can. Such other dicarboxylic acids include isophthalic acid, phthalic acid, 2-methylterephthalic acid, 2,6
-Dinaphthalenedicarboxylic acid and the like.

The dihydroxy compounds used in the present invention are ethylene glycol and cyclohexane dimethanol, but other dihydroxy compounds can be used in an amount that does not impair the properties of the obtained copolyester, for example, 1 mol% or less. Such dihydroxy compounds include 1,3-propanediol, 1,4-butanediol,
Neopentyl glycol, cyclohexanediol, 1,
3-bis (2-hydroxyethoxy) benzene, 1,4-bis (2-hydroxyethoxy) benzene, 2,2-bis (4-β-hydroxyethoxyphenyl) propane, bis (4-β-hydroxyethoxyphenyl) A dihydroxy compound having 3 to 15 carbon atoms such as sulfone is used.

The copolyester used in the present invention as described above,
Intrinsic viscosity [η] measured at 25 ° C in o-chlorophenol
Is preferably 0.5 to 1.5 dl / g, more preferably 0.6 to 1.2 dl / g. When the intrinsic viscosity [η] is 0.5 to 1.5 dl / g,
Excellent mechanical strength and excellent melt moldability.

The copolyester used in the present invention includes various compounding agents that are usually used by adding to the polyester, such as heat stabilizers, weather stabilizers, antistatic agents, lubricants, release agents, pigment dispersants, pigments or dyes. Can be added within a range that does not impair the purpose of the present invention.

The copolyester as described above can be produced according to a conventionally known polycondensation method employed in the production of polyethylene terephthalate. The dicarboxylic acid can be supplied to the reaction system as a dicarboxylic acid, can be supplied as a dialkyl ester thereof, or can be supplied as a diol ester of dicarboxylic acid.

Further, the dihydroxy compound can be supplied as a dihydroxy compound or can be supplied to the reaction system in the form of a dihydroxy ester of a carboxylic acid.

As the catalyst at the time of the copolycondensation, a conventionally known catalyst used in the production of polyethylene terephthalate can be used. As these catalysts, metals such as antimony, germanium and titanium or compounds thereof can be used. Compounds include oxides, hydroxides,
Halides, inorganic acid salts, organic acid salts, complex salts, double salts, alcoholates, phenolates and the like are used. These catalysts can be used alone or as a mixture of two or more. These catalysts can be supplied to the reaction system from the initial stage of the esterification reaction or transesterification reaction, or can be supplied to the reaction system before proceeding to the polycondensation reaction stage.

In addition, at the time of co-condensation, various additives such as a transesterification catalyst, a diethylene glycol production inhibitor, a heat stabilizer, a light stabilizer, a lubricant, a pigment, and a dye used in the production of polyethylene terephthalate can be used.

As a catalyst for these transesterification reactions, metal compounds such as calcium, magnesium, lithium, zinc, cobalt, and manganese can be used. These compounds may be in the form of oxides, hydroxides, halides,
Inorganic acid salts and organic acid salts are used. In addition, triethylamine, tri-n
Amines such as -butylamine, and quaternary ammonium compounds such as tetraethylammonium hydroxide and tetrabutylammonium hydroxide can be used. As a stabilizer such as a heat stabilizer, a phosphorus compound such as phosphoric acid, phosphorous acid, hypophosphorous acid, or an ester thereof can be used.

The copolyester used in the present invention is produced by a conventionally known melt polycondensation method, and in some cases, by employing a solid polycondensation method after the melt polycondensation method.

In the above-described melt polycondensation method, a so-called direct polycondensation method can be employed, and a so-called transesterification polycondensation method can also be employed. That is,
The melt polycondensation method will be described in more detail.For example, terephthalic acid or a dicarboxylic acid or its ester derivative containing the same as a main component, and a condensate of ethylene glycol with cyclohexanedimethanol or its dicarboxylic acid, A polyfunctional compound containing three or more carboxyl groups or hydroxyl groups is subjected to esterification or transesterification simultaneously or sequentially at a temperature of preferably 100 to 280 ° C. to form these initial polycondensates, Examples of the method include polycondensation at a temperature equal to or higher than its melting point, preferably at 200 to 300 ° C., while stirring or under a vacuum or under an inert gas flow.

Further, the copolyester used in the present invention can also be produced by extending the molecular weight by further solid-phase polycondensation of the copolyester obtained by the above-mentioned melt polycondensation method. Specific description of such a solid-phase polycondensation method includes, for example, refining a copolyester by a melt polycondensation method, and heating it at a temperature lower than its melting point, preferably at 180 to 240 ° C. under vacuum or an inert gas. A method of keeping under circulation can be adopted.

Hollow molded article The hollow molded article according to the present invention is made of the copolyester as described above, and has a stretching index defined as follows.
130 cm or more, preferably 140 to 220 cm, more preferably 150 to
It is stretched to 200cm.

Hereinafter, the stretching index of the hollow molded article according to the present invention will be described with reference to FIG. As shown in FIG. 1, a hollow molded body 1 according to the present invention includes a plug 2, an upper shoulder 3, a trunk 4, a lower shoulder 5, and a bottom 6.

When manufacturing such a hollow molded article 1, a preform 7 is used, and the preform 7 is shown by a dotted line in FIG.

The internal volume of the stretched hollow molded body as described above is the internal volume of the stretched hollow molded body 1 excluding the plug 2, and specifically,
This is the internal volume below the support ring 8 of the hollow molded body 1, more specifically, the volume of the hollow molded body below the virtual straight line 9.

The internal volume of the unstretched preform is the internal volume of the preform 7 excluding the plug 2, specifically, the internal volume below the support ring 8 of the preform 7, and more specifically. Means the volume of the preform below the virtual straight line 9.

Further, the inner surface area of the stretched hollow molded body is the inner surface area of the stretched hollow molded body 1 excluding the plug 2, and specifically, the inner surface area of the stretched hollow molded body below the support ring 8 of the hollow molded body 1. Surface area, more specifically, the inner surface area of the hollow molded body below the virtual straight line 9.

Inner surface area (excluding inner surface of plug) of stretched hollow molded body S
Can be measured by a fine division method in which a hollow molded body is divided, the inner surface shape is detected by a three-dimensional measuring machine, divided into minute parts, and the area of the minute parts is integrated. When the stretched hollow molded body has a simple shape, the body of the hollow molded body is assumed to be a cylinder, the lower and upper parts of the hollow molded body are each assumed to be a hemisphere, and the inner surface area is approximated. You can also ask.

The stretching index of the above-mentioned stretched hollow molded article is determined by the inner surface area of the stretched hollow molded article (excluding the cap part volume) and the inner volume of the unstretched hollow molded article (plug) together with the inner surface area of the stretched hollow molded article. (Excluding the partial volume) can be calculated. The internal volume of the hollow molded body can be easily measured by adding a liquid such as water. The units of the f value and the stretching index are cm ⁻¹ and cm, respectively.

In such a hollow molded body according to the present invention, the thickness of the body is the same as that of a conventionally known hollow molded body, and is usually 0.1 to
It is about 0.5 mm, preferably about 0.2 to 0.4 mm.

Next, a method for producing a hollow molded article according to the present invention will be described.

First, a preform is produced from the copolyester as described above, and this preform can be produced by a conventionally known method.

Such a preform is manufactured by a conventionally known method, but in the present invention, since the stretched portion of the preform is stretched higher than the conventionally known method, the length of the preform is smaller than that of the conventional preform. It is desirable to be formed shorter than the reform. If necessary, the diameter of the preform can be smaller than that of the conventional preform.

In the present invention, a hollow molded body is manufactured by blow molding the preform for forming a hollow molded body as described above.

At this time, the stretching index defined as described above of the obtained hollow molded body is 130 cm or more, preferably 140 to 220 cm,
More preferably, it is blow-molded to have a size of 150 to 220 cm.

The temperature during blow molding of the preform is 80 to 110
The temperature is preferably 90 to 105 ° C.

Effect of the Invention Since the hollow molded article according to the present invention is obtained by stretching a specific copolyester with a specific stretching index, it is excellent in transparency, moldability, gas barrier property, and economical efficiency. .

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

Example 1 Terephthalic acid and a dihydroxy compound in which 97 mol% of the dihydroxy compound is ethylene glycol and 3 mol% is cyclohexanedimethanol are esterified according to a conventional method, and [η] is 0.80 dl / g. A copolyester was produced.

The copolyester obtained as described above was molded using a molding machine M-100A manufactured by Meiki Seisakusho Co., Ltd. to obtain a preform for bottle formation. The molding temperature at this time was 250 to 270 ° C.

Next, the preform obtained as described above is CORPOP
A biaxially stretched bottle was obtained by molding with a LAST-01 LB-01 molding machine. The stretching temperature at this time was 80 to 110 ° C.

Unstretched preform inner volume (excluding spout) is 19cm
³ , and the internal volume (excluding the stopper) of the obtained stretched bottle was 1469 cm ³ .

The inner surface area of the stretched bottle (excluding the inner surface of the spout)
It was 678 cm ² .

 Therefore, the stretching index is calculated as follows.

The gas barrier property is evaluated based on the carbon dioxide gas permeability coefficient and the oxygen gas permeability coefficient. Using a PERMATRARC-IV carbon dioxide permeation tester (model: MODERN CONTROL, USA), the temperature is 23 ° C and the relative humidity is 0% by the PERMATRAN method. Under the conditions described above, the carbon dioxide permeability coefficient of a sample consisting of a section at the center of the bottle body having a thickness of 300 to 450 μm was measured.
Using the OXTRAN 100 model from TROL (USA), the thickness is 300 to 400μ by the OXTRAN method under the conditions of a temperature of 23 ° C and a relative humidity of 0%.
The oxygen gas permeability coefficient of a sample consisting of a section at the center of the body of the m bottle was measured.

The transparency was measured by cutting the body of the bottle and using a haze meter NDH-20D manufactured by Nippon Denshoku Co., Ltd.
The haze of the test piece was measured three times by a method according to 03, and the average value was evaluated.

Pressure strength is determined by using a pipe hydraulic pressure tester, placing the bottle in a 30 ° C constant temperature water bath, applying water pressure at a flow rate of 500 cc / min, measuring the pressure at breakage, and setting this value as the pressure strength. Done. Measurement was performed three times in each case (n = 3)
And averaged.

 Table 1 shows the results.

Example 2 Terephthalic acid and a dihydroxy compound in which 90 mol% of the dihydroxy compound is ethylene glycol and 10 mol% is cyclohexanedimethanol are esterified according to a conventional method, and [η] is 0.81 dl / g. A copolyester was produced.

In the same manner as in Example 1 using this copolyester,
A preform for a biaxially stretched molded article was manufactured, and a biaxially stretched bottle was manufactured using the preform.

The transparency and gas barrier properties of the obtained biaxially stretched bottle were evaluated in the same manner as in Example 1.

 Table 1 shows the results.

Comparative Examples 1-2 A biaxially-stretched bottle was produced in the same manner as in Examples 1-2, except that the stretching index was 95 cm and the total weight of the bottle (preform) was increased by 11%. Then, the transparency and gas barrier properties of the bottle were evaluated.

 Table 1 shows the results.

Example 3 Using the copolyester used in Example 1,
A preform for forming a bottle was obtained by molding with a molding machine ASB-50HT manufactured by ASB Corporation. The molding temperature at this time was 250 to 270 ° C.

Next, the preform obtained as described above is CORPOP
A biaxially stretched bottle was obtained by molding with a LAST-01 LB-01 molding machine. The stretching temperature at this time was 80 to 110 ° C.

Unstretched preform volume (excluding spout) is 4.9c
m ³ , and the internal volume (excluding the stopper) of the obtained stretched bottle was 519 cm ³ .

The internal surface area (excluding the stopper) of the stretched bottle was 345 cm ² .

 Therefore, the stretching index is calculated as follows.

The transparency and gas barrier properties of the obtained biaxially stretched bottle were evaluated in the same manner as in Example 1.

 Table 1 shows the results.

Example 4 A biaxially stretched preform was produced in the same manner as in Example 3 using the copolyester used in Example 2, and a biaxially stretched bottle was produced using this preform.

The transparency and gas barrier properties of the obtained biaxially stretched bottle were evaluated in the same manner as in Example 1.

 Table 1 shows the results.

Comparative Example 3 Example 3 was the same as Example 3 except that the stretching index was 92 cm and the total weight of the bottle (preform) was increased by 11%.
A biaxially stretched preform was produced in the same manner as described above, and a biaxially stretched bottle was produced using this preform.

The transparency and gas barrier properties of the obtained biaxially stretched bottle were evaluated in the same manner as in Example 1.

 Table 1 shows the results.

Comparative Example 4 Example 4 was repeated except that the stretching index was 92 cm and the total weight of the bottle (preform) was increased by 11%.
A biaxially stretched preform was produced in the same manner as described above, and a biaxially stretched bottle was produced using this preform.

The transparency and gas barrier properties of the obtained biaxially stretched bottle were evaluated in the same manner as in Example 1.

 Table 1 shows the results.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a hollow molded article according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Hollow molded object, 2 ... Plug part 3 ... Upper shoulder part, 4 ... Body part 5 ... Lower shoulder part, 6 ... Bottom part

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 22:00 C08L 67:02

Claims (1)

(57) [Claims] 1. A dihydroxy compound formed by esterification of terephthalic acid with a dihydroxy compound, wherein 85 to 99.5 mol% of the dihydroxy compound is ethylene glycol, 0.5 to 15 mol% is cyclohexane dimethanol, and the intrinsic viscosity [η] Is a copolyester having a stretch index of 0.5 to 1.5 dl / g, and has a stretch index defined as follows, which is highly stretched to 130 cm or more.