JP2741919B2 - Hollow molded body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hollow molded article having excellent properties such as gas barrier properties, transparency, moldability, and mechanical strength.

Technical Background of the Invention Conventionally, a so-called PET (polyester terephthalate) resin has been known as a polyester resin composition having gas barrier properties. PET resins are generally excellent in mechanical strength and transparency, and have good moldability such as melt moldability and stretchability, and are also lightweight. Therefore, molded articles made of PET resin are widely used, for example, as containers for sparkling beverages such as carbonated beverages or beer, or containers for seasonings, detergents, and cosmetics.

By the way, in containers for seasonings, detergents, cosmetics, and the like, the mechanical strength and the transparency may be a problem, but the gas barrier properties are rarely a problem.

However, for example, a container for sparkling beverage such as carbonated beverage or beer is filled with high-pressure carbon dioxide or the like, and therefore has a very high gas barrier property to prevent leakage of the internally-filled gas. Is required. In applications requiring such strict gas barrier properties, in order to use polyethylene terephthalate resin, gas barrier properties must be ensured by a method such as increasing the thickness of the container, which is disadvantageous in terms of cost. is there.

At present, the demand for polyester resin containers is increasing year by year. Therefore, in order to use a polyester resin container in the above-mentioned applications, it is necessary to impart a high gas barrier property to the polyethylene terephthalate resin without impairing the excellent properties of the currently used polyethylene terephthalate resin.

Under such demands, polyethylene terephthalate resin compositions in which various improvements have been made to polyethylene terephthalate resins have been proposed.

For example, Japanese Patent Application No. 62-20573 previously filed by the applicant of the present application
No. 9 proposes, as a PET resin composition having gas barrier properties that can withstand storage and transportation of carbonated beverages and the like, a resin composition in which a polyhydroxy polyether resin is blended with a PET resin. PET described in the above specification
Containers molded from the resin composition have better gas barrier properties than conventional PET resin containers.

Japanese Patent Application Laid-Open No. 61-72051 discloses a PE having excellent transparency.
As the T resin, a resin composition obtained by mixing a copolyester resin with a PET resin has been proposed by the present applicant.

Not limited to the above proposals, conventional research on improving the transparency and gas barrier properties of PET resin compositions has been
The emphasis has been placed on the composition of the resin composition, and attention has not been paid to the draw ratio when a PET resin preform is drawn to produce a hollow molded article such as a container.

An object of the present invention is to provide a hollow molded article having improved gas barrier properties of a polyester resin. More specifically, an object of the present invention is to provide a hollow molded body having improved gas barrier properties without impairing the transparency and mechanical properties of polyethylene terephthalate.

The first hollow molded article according to the present invention comprises more than 95% by weight of polyethylene terephthalate resin and 99% by weight or less, and 1% by weight or more and less than 5% by weight of a copolymerized polyester resin. The resin is composed of a dicarboxylic acid structural unit consisting of 20 to 100 mol% of an isophthalic acid component unit and 0 to 80 mol% of a terephthalic acid component unit, and 5 to 90 mol%.
A dihydroxyethoxyresorcinol component unit of
A dihydroxy compound constituent unit composed of 10 to 95 mol% of an ethylene glycol constituent unit and a dicarboxylic acid constituent unit 10
A polyester resin composition comprising a polyfunctional hydroxy compound constituent unit having at least three hydroxy groups with respect to 0 mole parts and 0.05 to 1.0 mole parts, and a stretch index defined as follows is as high as 130 cm or more. It is characterized by being.

The second hollow molded article according to the present invention comprises more than 95% by weight and less than 99% by weight of the polyethylene terephthalate resin and 1% by weight or more and less than 5% by weight of the copolymerized polyester resin. Is a dicarboxylic acid structural unit consisting of 20 to 100 mol% of an isophthalic acid component unit and 0 to 80 mol% of a terephthalic acid component unit;
Polyester resin comprising a 1,3-bis (2-hydroxyethoxy) benzene component unit or a 1,4-bis (hydroxyethoxy) benzene component unit and a dihydroxy compound constituent unit of 10 to 95 mol% of ethylene glycol component unit The composition is characterized in that it is highly stretched to a stretching index of 130 cm or more as defined below.

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

The hollow molded article according to the present invention comprises a polyester resin composition containing polyethylene terephthalate and a copolymerized polyester resin.

Polyethylene terephthalate resin The polyethylene terephthalate resin used in the present invention is a polyester having an ethylene terephthalate unit as a main constituent unit.

It is desirable that the content of the ethylene terephthalate composition unit in the polyethylene terephthalate resin is usually 50 mol% or more, preferably 70 mol% or more. The polyethylene terephthalate resin containing such an ethylene terephthalate structural unit is composed of a diol component unit and a dicarboxylic acid component unit. As the dicarboxylic acid component unit constituting the polyethylene terephthalate resin, a small amount of another aromatic dicarboxylic acid component unit may be contained in addition to the terephthalic acid component unit. Examples of such aromatic dicarboxylic acid component units include component units derived from isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and the like.

In ethylene terephthalate constituting the polyethylene terephthalate resin, the terephthalic acid component unit is usually
In an amount of 50 to 100 mol%, preferably 70 to 100 mol%, the aromatic dicarboxylic acid component unit other than the terephthalic acid component unit is usually in the range of 0 to 50 mol%, preferably 0 to 30 mol%. The amount of the ethylene glycol component unit, which is the diol component unit, is usually 50 to 100 mol%, preferably
The diol component unit other than the ethylene glycol component unit is usually in an amount of 0 to 50 mol%, preferably 0 to 30 mol%, and the polyfunctional compound component unit is usually 1 to 100 mol%. ２2 mol%, preferably 0-1 mol%.

The intrinsic viscosity [η] (value measured in a phenol-tetrachloroethane mixed solvent (weight ratio 1/1)) of the polyethylene terephthalate resin is usually 0.5 to 1.5 dl /.
g, preferably in the range of 0.6 to 1.2 dl / g, and the melting point is usually in the range of 210 to 265C, preferably 220 to 260C,
The glass transition temperature is usually 50 to 120 ° C., preferably 60 to 1
It is desirably in the range of 00 ° C.

Copolymerized Polyester Resin The first copolymerized polyester resin used in the present invention is composed of a dicarboxylic acid structural unit, a dihydroxy compound structural unit, and a polyfunctional hydroxy compound structural unit having at least three hydroxy groups.

In the first copolymerized polyester resin used in the present invention, of the dicarboxylic acid structural units, the isophthalic acid component unit is contained in an amount of 20 to 100 mol%, preferably 50 to 98 mol%,
It is desirable that the terephthalic acid component unit is present in an amount of 0 to 80 mol%, preferably 0.5 to 50 mol%.

When the amount of the isophthalic acid component unit in the dicarboxylic acid structural unit is within the above range, the obtained high-stretch molding polyester resin composition has particularly excellent gas barrier properties.

In the first copolymerized polyester resin used in the present invention, the dihydroxy ethoxy resorcinol component unit in the dihydroxy compound constituent unit is 5-90 mol%, preferably 10-85 mol%, and the ethylene glycol component is Desirably the units are present in an amount of 10-95 mol%, preferably 15-90 mol%.

When the amount of the dihydroxyethoxyresorcinol component unit in the dihydroxy compound constituent unit is less than 5 mol%, the generation of the oligomer tends to be unable to be suppressed,
On the other hand, if it exceeds 90 mol%, the rate of polycondensation tends to decrease.

This copolyester resin contains a polyfunctional hydroxy compound constituent unit having at least three hydroxy groups. This polyfunctional hydroxy compound structural unit is used in an amount of 0.05 to 1.0 based on 100 mol parts of the dicarboxylic acid component unit.
Desirably it is present in a molar part, preferably in an amount of 0.1 to 0.5 molar part. When the amount of the polyfunctional hydroxy compound constituent unit is less than 0.05 part by mole, the thickness unevenness of a molded article such as a container made of the polyester resin composition tends to be not sufficiently improved, and when the amount exceeds 1.0 part by mole, The resulting polyester resin composition tends to gel and become insoluble. Therefore, when producing a biaxially stretched hollow molded article using this resin composition, a preform (preliminary hollow molded article) is preliminarily obtained from this polyester resin composition.
Is difficult to mold, or the shrinkage rate of the obtained hollow molded article is undesirably increased.

Such polyfunctional hydroxy compound constituent units are derived from compounds such as trimethylolethane, trimethylolpropane and trimethylolmethane. Of these, trimethylolpropane is preferred.

Further, in the present invention, instead of the first copolymerized polyester resin as described above, a second copolymer composed of a dicarboxylic acid structural unit and a dihydroxy compound structural unit is used.
Can also be used.

Of the dicarboxylic acid constituent units constituting the copolymerized polyester resin, the isophthalic acid component unit is in an amount of 20 to 100 mol%, preferably 50 to 100 mol%, and the terephthalic acid component unit is 0 to 80 mol%. Preferably 0 to 50 mol%
Is preferably present in an amount of

When the amount of the isophthalic acid component unit in the dicarboxylic acid structural unit is within the above range, the obtained high-stretch molding polyester resin composition has particularly excellent gas barrier properties.

Further, among the dihydroxy compound constituent units constituting the copolymerized polyester resin, 1,3-bis (2-hydroxyethoxy) benzene component unit or 1,4-bis (hydroxyethoxy) benzene component unit is 5-90 mol%. It is preferred that the ethylene glycol component units be present in an amount of from 10 to 95 mol%, preferably from 10 to 85 mol%, and preferably from 15 to 90 mol%.

1,3-bis (2-hydroxyethoxy) benzene component unit in the dihydroxy compound structural unit or
When the amount of the 1,4-bis (hydroxyethoxy) benzene component unit is less than 5 mol%, the generation of oligomer tends not to be suppressed, while when it exceeds 90 mol%, the rate of polycondensation tends to decrease. Occurs.

The molecular weight of the first and second copolymerized polyester resins used in the present invention is not particularly limited as long as it is within a range in which various molded articles such as containers can be produced from the obtained polyester resin composition. It is desirable that the relative viscosity (IV) of the polyester resin in the chlorophenol solvent is 0.6 dl / g or more, preferably in the range of 0.8 to 0.85 dl / g.

In the polyester resin composition used in the present invention, the polyethylene terephthalate resin is more than 95% by weight and 99% by weight or less, preferably 96% by weight, based on the total weight of the composition.
The copolymerized polyester resin is present in an amount of 1% by weight or more and less than 5% by weight, preferably 2-4% by weight.

By adjusting the blending amount of the polyethylene terephthalate resin and the copolymerized polyester resin to an amount within the above range, a polyester resin composition having improved gas barrier properties without impairing the transparency and mechanical properties of polyethylene terephthalate is provided. can get.

To produce the polyester resin composition used in the present invention, a method of mixing a polyethylene terephthalate resin and a copolymerized polyester resin with, for example, a Henschel mixer, a V blender, a ribbon blender, a tumbler blender, etc. A method of melt-mixing or pulverizing with an extruder, a twin-screw extruder, a kneader, a Banbury mixer or the like can be employed.

In the polyester resin composition used in the present invention, various compounds usually used in addition to polyester, such as a heat stabilizer, a weather stabilizer, an antistatic agent, a lubricant, a release agent, a pigment dispersant, a pigment or a dye. Agents can be added within a range that does not impair the purpose of the present invention.

Hollow molded article The hollow molded article according to the present invention is composed of the polyester resin composition as described above, and has a stretching index defined as follows, which is as high as 130 cm or more, preferably 140 to 220 cm, more preferably 150 to 200 cm. Have been.

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 manufactured from the polyester resin as described above. This preform can be manufactured 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.

The hollow molded article thus obtained is a polyester resin that forms a bottle at four locations on the periphery S at 1/2 the height L from the bottom (support ring 8) to the bottom of the hollow molded article (bottle). The average value of the density value of the composition is 1.368 g
/ cm ³ or more, preferably 1.370 g / cm ³ or more.

Effect of the Invention Since the hollow molded article according to the present invention is obtained by stretching a polyester resin composition containing a polyethylene terephthalate resin and a specific copolymerized polyester resin at a specific ratio at a specific stretching index, buckling strength, dropping It has excellent mechanical properties such as strength and transparency, and also has excellent gas barrier properties.

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

Example 1 In producing the polyester resin composition for high-stretch molding according to the present invention, the following resins were used.

Polyethylene terephthalate resin: J 135 manufactured by Mitsui Pet Resin Co., Ltd. (The relative viscosity (IV) measured in o-chlorophenol at 25 ° C. is 0.85 dl / g.) Copolymerized polyester resin: Isophthalic in dicarboxylic acid constituent unit The acid component unit is 90 mol% and the terephthalic acid component unit is 10 mol%, the dihydroxy ethoxy resorcinol component unit is 15 mol% and the ethylene glycol component unit is 85 mol% in the dihydroxy compound constitution unit, and the dicarboxylic acid constitution unit is further included. This is a copolymerized polyester resin containing 0.3 mol part of a trimethylolpropane structural unit per 100 mol parts. The relative viscosity (IV) measured at 25 ° C. in o-chlorophenol is 0.85 dl / g.

After mixing 1% by weight of the copolymerized polyester resin and 99% by weight of the polyethylene terephthalate resin, the resulting polyester resin composition (I) was mixed with Meiki Seisakusho Co., Ltd.
A preform for bottle formation was obtained by molding with a molding machine M-100A. The molding temperature at this time was 270 to 290 ° 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 measured 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. Was. The measurement was performed three times (n = 3) in each case, and the average value was adopted.

 Table 1 shows the results.

Example 2 In Example 1, as a copolymerized polyester resin,
Using the following resin, 4% by weight of copolyester resin
A preform for a biaxially stretched molded article was produced in the same manner as in Example 1 except that the polyethylene terephthalate resin and 96% by weight of the polyethylene terephthalate resin were used, and a biaxially stretched bottle was produced using this preform.

Copolyester resin: 90 mol% of isophthalic acid component unit and 10 mol% of terephthalic acid component unit in dicarboxylic acid constitutional unit, 7.5 mol% of dihydroxyethoxyresorcinol component unit and ethylene glycol component unit in dihydroxy compound constitutional unit 92.5 mol%, and based on 100 mol parts of the dicarboxylic acid structural unit,
It is a copolymerized polyester resin containing 0.3 mol part of a trimethylolpropane structural unit. The relative viscosity (IV) measured at 25 ° C. in o-chlorophenol is 0.85 dl / g.

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.

Comparative Example 3 A biaxially stretched bottle was produced in the same manner as in Comparative Example 1 except that only the polyethylene phthalate resin was used without using the copolymerized polyester resin, and the transparency and gas barrier properties of the bottle were measured. evaluated.

 Table 1 shows the results.

Comparative Example 4 In Comparative Example 1, a biaxially stretched bottle was produced in the same manner as in Example 1 except that only the polyethylene phthalate resin was used without using the copolymerized polyester resin, and the transparency and gas barrier properties of the bottle were measured. evaluated.

 Table 1 shows the results.

Example 3 Polyester resin composition [I] used in Example 1
Using a molding machine ASB-50HT manufactured by Nissei ASB Co., Ltd.
A bottle forming preform was obtained. The molding temperature at this time is
260-270 ° 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 2 shows the results.

Example 4 A biaxially stretched preform was produced in the same manner as in Example 3 using the polyester resin composition 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 2 shows the results.

Comparative Example 5 A biaxially stretched preform was produced in the same manner as in Example 3, except that the stretching index was 92 cm and the total weight of the preform was increased by 11%. A biaxially stretched bottle was manufactured.

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

 Table 2 shows the results.

Comparative Example 6 A biaxially stretched preform was produced in the same manner as in Example 4, except that the stretching index was set to 92 cm and the total weight of the preform was increased by 11%. A biaxially stretched bottle was manufactured.

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

 Table 2 shows the results.

Comparative Example 7 Using only the polyethylene terephthalate resin, a biaxially stretched preform was manufactured in the same manner as in Comparative Example 5 except that the stretching index was 92 cm and the total weight of the preform was increased by 11%.

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

 Table 2 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 Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI B29K 67:00 B29L 22:00 (56) References JP-A-2-217222 (JP, A) JP-A-59-230022 (JP) JP-A-62-232451 (JP, A) JP-A-53-115394 (JP, A)

Claims (2)

(57) [Claims] 1. A 95% by weight polyethylene terephthalate resin.
More than 99% by weight and more than 1% by weight and less than 5% by weight of the copolymerized polyester resin, wherein the copolymerized polyester resin contains 20 to 100% by mole of isophthalic acid component unit and 0 to 80% by mole of terephthal A dicarboxylic acid structural unit composed of an acid component unit, 5-90 mol% of a dihydroxyethoxyresorcinol component unit, and 10
A dihydroxy compound structural unit consisting of ~ 95 mol% of ethylene glycol component units, and a dicarboxylic acid structural unit of 100
It comprises a polyester resin composition comprising a polyfunctional hydroxy compound constituent unit having at least three hydroxy groups with respect to a molar part of 0.05 to 1.0 mole part, and a stretch index defined as follows is highly stretched to 130 cm or more. A hollow molded article, characterized in that: 2. A 95% by weight polyethylene terephthalate resin.
More than 99% by weight and more than 1% by weight and less than 5% by weight of the copolymerized polyester resin, wherein the copolymerized polyester resin contains 20 to 100% by mole of isophthalic acid component unit and 0 to 80% by mole of terephthal A dicarboxylic acid constituent unit consisting of an acid component unit and 5-90 mol%
Polyester resin composition comprising a 1,3-bis (2-hydroxyethoxy) benzene component unit or a 1,4-bis (hydroxyethoxy) benzene component unit and a dihydroxy compound constituent unit composed of 10 to 95 mol% of an ethylene glycol component unit A hollow molded article, characterized by being stretched at a high stretch index of 130 cm or more as defined below.