JP3159387B2 - Heat-resistant light-shielding bottle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resin bottle manufactured by stretch blow molding, and more particularly to a bottle excellent in heat resistance and light shielding properties.

[Problems to be solved by conventional technology and invention]

In recent years, so-called hot fill (heating filling), which fills a polyester bottle with a liquid at 80 to 95 ° C, and pasteurizing (heat sterilization) by a hot shower, have been performed. Sex is required. This is because the hot fill first exposes the mouth to the hot liquid, and the hot shower usually pastes the hot shower from the top of the bottle, even in pasteurizing with a hot shower. Is caused.

Under such circumstances, various attempts have been made to impart heat resistance to polyester bottles.

As such an attempt, JP-A-63-19208 discloses a method of manufacturing a heat-resistant bottle by co-injecting a polyester and a heat-resistant resin to form a multilayered preformed body and stretch-blow-molding it. Is disclosed. In addition, the present applicant has previously proposed that the bottles be further multi-layered by improving the co-injection method (Japanese Patent Application No. Hei 1-1632).
No. 61 and Japanese Patent Application No. 2-16329). These multilayer bottles have many heat-resistant resin layers especially at the mouth, and have good heat resistance.

It has also been proposed to whiten the mouth by crystallization by heat treatment, thereby imparting heat resistance to the mouth (JP-A-57-201631, JP-A-58-217326, JP-A-58-217326).
No. 59-138417, JP-B-59-33101, etc.).

On the other hand, many drinks such as milk drinks and lactic acid drinks deteriorate when exposed to light for a long time. Therefore, from production to consumption, in order to prevent deterioration and guarantee quality,
It is desirable that the bottle enclosing them has a light-shielding property.

Such light-shielding bottles include, for example, colored glass bottles, and bottles further wrapped with paper. However, they are extremely restricted in design and often have poor appearance. In addition, handling is inconvenient because of its heavy weight.

Further, as a blow-molded bottle, a bottle made of a resin in which titanium white (TiO ₂ ) is dispersed in polystyrene has relatively excellent light-shielding properties, and is used in part. However, although the bottle has a high light-shielding property with respect to ultraviolet rays, a large amount of visible light is transmitted therethrough, so that the contents are easily deteriorated, and the shelf life is not sufficiently long.

Accordingly, an object of the present invention is to provide a blow molded bottle having heat resistance and excellent light shielding properties.

[Means for solving the problem]

In view of the above objects, as a result of intensive studies, the present inventor has found that the mouth of a blow-molded bottle is whitened by heat treatment, and the light-reflective pigment, light-absorbing pigment and iron oxide are contained in the polyester forming the mouth and body. It has been found that by simultaneously containing, it is possible to obtain a material having excellent heat resistance and light-shielding properties, and completed the present invention.

That is, the heat-resistant and light-shielding bottle of the present invention is made of a resin having a mouth, a support ring provided at a lower end of the mouth, a shoulder following the support ring, a body and a bottom. The mouth is whitened by crystallization due to heat treatment and has heat resistance, and the resin forming the mouth and body is 100 to 100 parts by weight of polyester, and 2.5 to 6.0 parts by weight of a light-reflective pigment. And light absorbing pigment 0.005 to 0.0
It is characterized by containing 15 parts by weight and 0.05 to 0.1 part by weight of iron oxide and having light shielding properties.

It is preferable to use titanium white as the light reflective pigment and to use carbon black as the light absorbing pigment.

In order to further improve the heat resistance of the mouth of the bottle, it is desirable to provide a heat-resistant resin layer at the mouth.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a bottle according to an embodiment of the present invention. The bottle 10 includes a mouth 1, a shoulder 2, a support ring 5 provided therebetween, a body 3, and a bottom 4. Further, the bottle 10 may be entirely formed of polyester, but preferably has a multilayer structure including the polyester layer 7 and the heat-resistant resin layer 9. That is, in FIG.
The mouth 1 and the support ring 5 are composed of three heat-resistant resin layers 9 and 2
It has a five-layer structure consisting of a polyester layer 7
And the bottom part 4 is composed of a single pigment-containing polyester layer 7.

Further, as shown in an enlarged manner in FIG. 2, the mouth portion 1 and the support ring 5 are crystallized by a heat treatment described later (dotted portion). Therefore, it is whitened and the heat resistance is further improved.

The multi-layer bottle 10 is manufactured by, for example, co-injection molding a polyester resin and a heat-resistant resin by a method exemplified in JP-A-1-146707, and biaxially stretch-blow molding the preformed body. Manufactured by In this case, by changing the number of resin flow paths in the hot runner nozzle for injecting the resin and the timing of starting and stopping co-injection, the number of layers in each part after completion can be appropriately changed.

As the polyester resin constituting the polyester layer 7, a thermoplastic resin comprising a saturated dicarboxylic acid and a saturated dihydric alcohol can be used. As saturated dicarboxylic acids, terephthalic acid, isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyldicarboxylic acids,
Aromatic dicarboxylic acids such as diphenoxyethane diethane dicarboxylic acids, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, decane-1,10-dicarboxylic acid, and cycloaliphatic dicarboxylic acids such as cyclohexane dicarboxylic acid; Can be used. Examples of the saturated dihydric alcohol include ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol,
Aliphatic glycols such as polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol, neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, 2,2-bis (4'-β-hydroxyethoxyphenyl) ) Propane, other aromatic diols and the like can be used. A preferred polyester is polyethylene terephthalate consisting of terephthalic acid and ethylene glycol.

The polyester resin has an intrinsic viscosity of 0.5 to 1.5, preferably 0.55 to 0.85. In addition, such polyesters are produced by melt polymerization and are subjected to a reduced pressure treatment or a heat treatment in an inert gas atmosphere at a temperature of 180 to 250 ° C., or oligomers and acetaldehydes which are low molecular weight polymers by solid phase polymerization. Those having a reduced content are preferred.

2.5 to 6.0 parts by weight of a light reflective pigment is added to 100 parts by weight of the polyester. As the light-reflective pigment, white pigments such as titanium white (TiO ₂ ), aluminum powder, mica powder, zinc sulfide, and zinc white are preferable, and rutile-type titanium white is particularly preferable. When light enters the resin, the light is scattered by the particles of the light-reflective pigment. If it is less than 2.5 parts by weight, a sufficient light scattering effect cannot be obtained, and if it exceeds 6.0 parts by weight, the effect is not significantly improved even if added more, and the moldability of the resin deteriorates. The preferred content of the light reflective pigment is 4 to 5.3 parts by weight.

Further, 0.005 to 0.015 parts by weight of a light absorbing pigment is further added to 100 parts by weight of the polyester. As the light-absorbing pigment, a colored pigment such as carbon black, ceramic black, and bone black is preferable, and carbon black, which is a black pigment, is particularly preferable. Since the light scattered by the particles of the light-reflective pigment is absorbed by the particles of the light-absorbing pigment, the light does not pass through the resin. If the amount of the light-absorbing pigment is less than 0.005 parts by weight, a sufficient light absorbing effect cannot be obtained, and if the amount exceeds 0.015 parts by weight, the effect is not significantly improved even if added more, and the color of the resin becomes dark and the Appearance is impaired. The preferred content of the light absorbing pigment is 0.009 to 0.012 parts by weight.

Further, in the polyester layer of the present invention, iron oxide (Fe ₂ O ₃ ) generally referred to as red iron oxide is used in order to conceal the above-mentioned light-absorbing pigment, suppress the color development thereof, and keep the color of the bottle good. Add 0.05 to 0.1 parts by weight. If the amount is less than 0.05 part by weight, the above effect cannot be obtained. If the amount exceeds 0.1 part by weight, coloring by iron oxide becomes remarkable, and the appearance of the bottle is impaired. The preferred content of iron oxide is 0.07 to 0.09 parts by weight.

Furthermore, in the polyester layer, a lubricant, a stabilizer, an antioxidant, a heat deterioration inhibitor, as long as the object of the present invention is not impaired,
Additives such as an ultraviolet ray deterioration preventing agent, an antistatic agent, and an antibacterial agent and other resins can be added in appropriate amounts.

On the other hand, the resin constituting the heat-resistant resin layer 9 includes polyarylate, polycarbonate, polyethylene naphthalate, polyacetal, polysulfone, polyetheretherketone, polyethersulfone, polyetherimide, polyphenylenesulfide, and these resins and polyethylene. A blend polymer with terephthalate, a blend polymer between the above-mentioned heat-resistant resins, a blend polymer of two or more kinds of the above-mentioned heat-resistant resins with polyethylene terephthalate, a U polymer (manufactured by Unitika, a blend polymer of polyarylate and polyethylene terephthalate) ), Polymer alloys of polyarylate with polycarbonate and polyethylene terephthalate, and the like.

In addition to the polyester layer 7 and the heat-resistant resin layer 9,
A resin layer having excellent gas barrier properties such as oxygen and carbon dioxide may be provided.

The crystallization of the mouth can be performed by heating the mouth 1 from its surroundings. Specifically, after the preformed article is molded, the mold is cooled and released, and then heated in a separate step (off-line method). It can be carried out by any of the crystallization methods (in-line method). In either method, it is preferable to use a heating mold in which a heater is built in a lip mold for gripping the mouth 1 because the apparatus does not become large-scale.

The heating temperature in the off-line method needs to be higher than the crystallization temperature of the polyester layer 7, and it is particularly preferable that the heating temperature is 140 to 210C above the glass transition point. Heating temperature
If the temperature is lower than 160 ° C., the crystallization step takes too much time. If the temperature is higher than 200 ° C., bubbles are generated due to rapid heating of the polyester layer, and the shape of the mouth is broken. The preferred heating temperature is 160-180 ° C. The heating time is 70 to 150 seconds.

On the other hand, in the in-line method, since both the polyester layer and the heat-resistant resin layer are crystallized through a step of gradually cooling from a high-temperature molten state, it is not necessary to heat the lip mold itself to a high temperature. In this method, the heating temperature at which slow cooling and warming can be performed is specifically preferably 90 to 110 ° C. If the heating temperature is lower than 90 ° C., crystallization cannot be sufficiently performed in the in-line molding cycle (usually for 70 to 150 seconds). On the other hand, when the temperature exceeds 130 ° C., crystallization of the polyester layer occurs from the mouth to the trunk, and the shoulder portion becomes opaque after the bottle is formed. The preferred heating temperature is 90-110 ° C. At this heating temperature, a time required for crystallization of 70 to 150 seconds is sufficient as in the above-described in-line molding cycle.

(Operation)

Since the mouth of the bottle of the present invention is whitened by crystallization due to heat treatment, the heat resistance of the mouth is significantly improved.

Also, the bottle of the present invention has a sufficient light-shielding property,
It is thought to be due to the following reasons. That is, as shown in FIG. 3, the incident light is scattered by the particles 20 of the light-reflective pigment dispersed in the polyester layer 7, and the optical path when passing through the polyester layer 7 becomes extremely long. Since the particles 30 of the light-absorbing pigment are also present in the polyester layer 7, the scattered light hits the particles 30 of the light-absorbing pigment, and the probability of absorption is high. For this reason, even if the amount of the light-absorbing pigment is relatively small, the overall absorbance is sufficiently high. By such a principle, sufficient light-shielding properties can be obtained without using a large amount of light-absorbing pigment.

The present invention will be described in more detail with reference to the following specific examples.

Example 1 Polyethylene terephthalate resin (manufactured by Unitika Ltd.)
(NEH-2050) 100 parts by weight, 5.29 parts by weight of titanium white, 0.01 part by weight of carbon black, 0.07 part by weight of iron oxide, and an alkylenebisfatty acid amide 0.
1 part by weight and 0.16 parts by weight of a higher fatty acid salt were added to prepare a polyester resin.

As a heat resistant resin, a blend polymer of polyethylene terephthalate and polyarylate (U polymer 840)
0, manufactured by Unitika Ltd.).

Using the polyester resin and the heat-resistant resin, a preform was molded by coinjection molding.

The opening of the obtained multilayer preform was heated at 170 ° C. for 140 seconds by a heating mold having a heater built in a lip mold to crystallize.

Next, the preform was biaxially stretch blow-molded to have a substantially uniform thickness of about 0.35 mm and a capacity of 90 mm.
A 0 ml milky white bottle was produced. This bottle had a multilayer structure consisting of five layers as shown in FIG.

When the light transmittance of the body of the bottle was measured using a spectrophotometer, it was confirmed that 100% of the light having a wavelength of 600 nm or less was cut, and that the bottle had excellent light-shielding properties.

The bottle was heated and filled with a lactic acid beverage, sealed, stored for one year, and subjected to a sensory test. As a result, it was confirmed that the bottle exhibited good taste and a sufficiently long shelf life was guaranteed.

Comparative Examples 1 to 3 As a comparison, a commercially available colored bottle made of polystyrene (about 0.5 mm in thickness) was used (Comparative Example 1).

2.5 parts by weight of titanium white is added to 100 parts by weight of polyethylene terephthalate resin (NEH-2050),
A polyester resin was prepared. Next, using this polyester resin, injection molding and blow molding were performed in the same manner as in Example 1 to form a bottle having a thickness of about 0.35 mm (Comparative Example 2).

To 100 parts by weight of polyethylene terephthalate resin (NEH-2050), 5.0 parts by weight of titanium white was added,
A polyester resin was prepared. Next, using this polyester resin, injection molding and blow molding were performed in the same manner as in Example 1 to form a bottle having a thickness of about 0.35 mm (Comparative Example 3).

In Comparative Examples 1 to 3, crystallization of the mouth was not performed.

Using the bottles of Comparative Examples 1 to 3, the light transmittance was measured with a spectrophotometer. The result is shown in FIG.

〔The invention's effect〕

As described above, when light enters the bottle of the present invention, the particles of the light-reflective pigment in the polyester layer scatter light, and the optical path in the polyester layer becomes longer. Therefore, the probability that the scattered light is absorbed by the particles of the light-absorbing pigment is increased, and the light-shielding property of the bottle is improved. Therefore, the shelf life of the contents can be significantly lengthened.

Further, when iron oxide is further added to the polyester layer, the coloring of the light-absorbing pigment is suppressed, and the color tone of the bottle can be kept good.

Furthermore, since the mouth is whitened by crystallization, the heat resistance of the mouth is significantly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a bottle according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the mouth of the bottle of FIG. 1, and FIG. FIG. 4 is an enlarged cross-sectional view of a polyester layer for explanation, and FIG. 4 is a graph showing a result obtained by measuring a light shielding property of a bottle using a spectrophotometer. DESCRIPTION OF SYMBOLS 1 ... Mouth part 2 ... Shoulder part 3 ... Body part 4 ... Bottom part 5 ... Support ring 7 ... Polyester layer 9 ... Heat resistant resin layer 10 ... Bottle 20 ... Light reflective pigment particles 30 …… Light absorbing pigment particles

Claims (9)

(57) [Claims] 1. A resin bottle having a mouth portion, a support ring provided at a lower end of the mouth portion, a shoulder portion following the support ring, a body portion and a bottom portion, wherein the mouth portion is formed by heat treatment. The resin which is whitened by crystallization and has heat resistance, and the resin forming the body is made of polyester 100
2.5 to 6.0 parts by weight of a light-reflective pigment, 0.005 to 0.015 parts by weight of a light-absorbing pigment, and 0.05 to 0.
A heat-resistant and light-shielding bottle comprising 1 part by weight and having light-shielding properties. 2. The heat-resistant and light-shielding bottle according to claim 1, wherein the light-reflective pigment is titanium white. 3. The heat-resistant and light-shielding bottle according to claim 1, wherein the light-absorbing pigment is carbon black. 4. A resin bottle having a mouth, a support ring provided at a lower end of the mouth, a shoulder following the support ring, a body and a bottom, wherein the mouth is heat-treated. It is whitened by crystallization and has heat resistance, and has a multilayer structure composed of a polyester layer and a heat-resistant resin layer, and the resin forming the body is 100 parts by weight of polyester, A heat-resistant and light-shielding bottle comprising 2.5 to 6.0 parts by weight of a light-reflective pigment, 0.005 to 0.015 parts by weight of a light-absorbing pigment, and 0.05 to 0.1 part by weight of iron oxide and having light-shielding properties. 5. The heat-resistant and light-shielding bottle according to claim 4, wherein the light-reflective pigment is titanium white. 6. The heat-resistant and light-shielding bottle according to claim 4, wherein the light-absorbing pigment is carbon black. 7. A resin bottle having a mouth, a support ring provided at a lower end of the mouth, a shoulder following the support ring, a body and a bottom, wherein the mouth is formed by heat treatment. The resin which is whitened by crystallization and has heat resistance, and the resin forming the body is made of polyester 100
2.5 to 6.0 parts by weight of titanium white, 0.005 to 0.015 parts by weight of light-absorbing pigment, and 0.05 to 0.05 parts by weight of iron oxide
A heat-resistant light-shielding bottle containing 0.1 parts by weight and having light-shielding properties. 8. The heat-resistant and light-shielding bottle according to claim 7, wherein the light-absorbing pigment is carbon black. 9. A resin bottle having a mouth portion, a support ring provided at a lower end of the mouth portion, a shoulder portion following the support ring, a body portion and a bottom portion, wherein the mouth portion is formed by heat treatment. The resin which is whitened by crystallization and has heat resistance, and the resin forming the body is made of polyester 100
2.5 to 6.0 parts by weight of light-reflective pigment, 0.005 to 0.015 parts by weight of carbon black, and 0.05% by weight of iron oxide
A heat-resistant light-shielding bottle containing 0.1 to 0.1 parts by weight and having light-shielding properties.