TW201341159A - Container manufacturing method and container - Google Patents

Abstract

A method for manufacturing containers that use a polypropylene resin composition as resin starting material, wherein the method comprises: an injection molding process of placing a melted polypropylene resin composition in a prescribed injection molding die to form a preform and after cooling said preform to 110 DEG C or less inside the injection molding die, releasing same from the injection molding die; and a stretch blow molding process of stretch-blow molding the preform to form the container.

Description

Container manufacturing method and container

The present invention relates to a method for producing a container and a container, and more particularly to a method and a container for producing a container obtained by molding a polypropylene resin composition.

Various containers for storing cosmetics, beverages, and the like have been provided, and plastic containers excellent in strength, impact resistance, corrosion resistance, light weight, moldability, and economy have been used. In particular, for the purpose of confirming the color or state of the contents from the outside, a transparent plastic container capable of confirming the storage amount is often used. Among the transparent plastic containers, containers in the shape of cans, bottles, pots, and the like (hereinafter referred to as "clear bottles") are widely used.

In order to correctly confirm the contents filled in the transparent bottle from the outside, it is necessary to increase the transparency of the transparent bottle. On the other hand, in order to achieve protection of the contents, it is necessary to make the transparent bottle have a specific strength. In this way, both the transparency and the specific strength of the transparent bottle are required. Therefore, as a container which can satisfy the above requirements, a transparent bottle made of polyethylene terephthalate (PET, polyethylene terephthalate) (hereinafter referred to as " PET transparent bottle").

PET transparent bottles can achieve a haze value of less than 5% as a transparency index, thereby achieving higher transparency. Further, the PET transparent bottle can obtain a buckling strength of 100 N or more in the longitudinal direction (up and down direction) in a bottle having a capacity of 200 ml (a wall thickness of about 0.7 mm) without providing a rib to increase the hardness. When the buckling strength is 100 N or more, when the transparent bottle is placed in a corrugated box or the like for transportation and storage, it can be operated without special attention. Work.

Recently, in view of solvent resistance, economy, easiness of conversion to biological materials, and the like, a transparent bottle containing a composition containing a polypropylene resin (hereinafter sometimes abbreviated as PP resin) has been disclosed. Document 1).

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2006-307122

However, in the case where a transparent bottle was produced from a polypropylene resin composition in place of PET, a structure having a high degree of transparency such as a transparent bottle made of PET was not realized.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a container which can achieve high transparency from a polypropylene resin composition, and a container.

According to one embodiment, there is provided a method of producing a container using a polypropylene resin composition as a resin material, and comprising: an injection molding step of introducing the melted polypropylene resin composition into a specific one Forming a preform in the injection molding die, and releasing the preform from the injection molding die after cooling the preform to 110 ° C or lower in the injection molding die; and extending the blow molding step, which is The molded body is stretch blow molded to form a container.

According to another aspect, a method of manufacturing a container using a poly The propylene resin composition is a resin raw material, and includes an injection molding step of introducing the melted polypropylene resin composition into a specific injection molding die to form a preform, and the injection molding die Thereafter, the preform is cooled to a temperature not exceeding the crystallization temperature of the polypropylene resin composition, and then released from the injection molding die; and an extension blow molding step of stretching the preform Blow molding to form a container.

According to another aspect, there is provided a container in which a polypropylene resin composition is formed as a resin material, and a wall thickness of the main body portion is 0.7 mm or more, and a haze value of the main body portion is less than 5%.

Further, any combination of the above constituent elements and the conversion of the present invention between the method, the device, and the like are also effective as an aspect of the present invention.

Embodiments of the present invention will be described with reference to the drawings.

Hereinafter, embodiments of the present invention will be described using the drawings. In the drawings, the same components are denoted by the same reference numerals, and the description is omitted as appropriate.

In this embodiment, the container may be a transparent bottle.

(transparent bottle)

Fig. 1 is a three-side view showing an example of the configuration of the transparent bottle 10 in the present embodiment. (A) is a front view of the transparent bottle 10, (B) is a side view of the transparent bottle 10, and (C) is a plan view of the transparent bottle 10.

The transparent bottle 10 shown in Fig. 1 is used to store liquids such as cosmetics and refreshing drinks. A container for the shape of a bottle (can, bottle, pot, etc.). The transparent bottle 10 includes a main body portion (container body) 11 and a neck portion 12, and is formed integrally. In the present embodiment, the transparent bottle 10 is a resin molded article produced by the injection stretch blow molding method.

The main body portion 11 has a substantially elliptical column shape, and a concave portion 17 is formed in the upper half portion. The main body portion 11 may have any shape such as a substantially cylindrical shape, a substantially rectangular column, a substantially hexagonal column, or a substantially eight-corner column, and may have a rib or a concave-convex pattern. The boundary portions 15 and 16 of the main body portion 11 and the bottom portion 14 and the shoulder portion 13 are respectively chamfered or curved. Further, in the neck portion 12, a screw for mounting the top cover is formed.

Further, the shape of the transparent bottle in the present invention is not limited to the shape shown in Fig. 1.

The transparent bottle 10 of the present embodiment is formed by using a polypropylene resin, that is, a resin composition containing a polypropylene homopolymer and/or a polypropylene copolymer as a resin material. Specifically, for example, a resin containing a polypropylene homopolymer or a propylene-ethylene random copolymer can be used. Further, the resin composition may contain a small amount of additives such as a weather resistance improver, an ultraviolet absorber, an antioxidant, and a crystal nucleating agent.

The resin material used in the transparent bottle 10 of the present embodiment will be described.

As the resin raw material, a polypropylene-based resin or a small amount of a additive is added thereto. The polypropylene resin (hereinafter sometimes abbreviated as PP resin) may be a mixture of a polypropylene homopolymer (polypropylene monomer) and a propylene copolymer alone or in plural. Here, the propylene monomer in the monomer unit contained in the propylene copolymer-based copolymer is the copolymer most in a weight-to-weight ratio.

In the present embodiment, an isotactic polymer can be used as the polypropylene homopolymer. In the present embodiment, a random copolymer, a block copolymer or the like can be used as the propylene copolymer. Examples of the monomer to be copolymerized with the propylene monomer in the propylene copolymer include ethylene or an aliphatic unsaturated hydrocarbon (olefin) monomer having a C ₄ to C ₁₀ degree, a styrene monomer, an acrylic monomer, and the like. More often, for example, an aliphatic unsaturated hydrocarbon (olefin) monomer can be used. As the resin material of the present embodiment, a propylene-ethylene random copolymer-based resin can be used. The propylene-ethylene random copolymer-based resin may be not only a propylene-ethylene random copolymer but also a small amount of a third aliphatic unsaturated hydrocarbon (olefin) monomer unit in a propylene-ethylene random copolymer. A copolymer of the above components. The third aliphatic unsaturated hydrocarbon (olefin) monomer may be an aliphatic unsaturated hydrocarbon monomer having a C ₄ to C ₁₀ degree.

In the present embodiment, a propylene-ethylene random copolymer is used as a resin raw material of the transparent bottle 10, but a propylene homopolymer or a mixed resin of a propylene copolymer and a propylene homopolymer may be used. , manufacturing transparent bottle 10.

Further, as the material of the transparent bottle 10, a polypropylene resin produced from a vegetable material may be used instead of the petroleum-derived propylene-based resin. The polypropylene resin is more easily produced from a plant material, and the use of the polypropylene resin produced from the plant material can suppress the generation of carbon dioxide in a broad sense, thereby preventing global warming.

The polypropylene resin has high strength, no hygroscopicity, and exhibits a strong resistance to chemicals. Therefore, it is suitable as a material of the transparent bottle 10 of this embodiment. The transparent bottle 10 of the present embodiment is a polypropylene resin. Since the composition is produced, it can be preferably used as a container for a cosmetic container or a food container in which impurities are prevented from being mixed, a solution which is easily reacted with a chemical substance or a chemical substance is dissolved. In this case, in the resin material of the transparent bottle 10 of the present embodiment, it is preferable that the resin is not contained in the storage bottle, and the additive which bleeds out to the storage contents or causes chemical changes due to light or the like. Or, add as little as possible. As described above, the transparent bottle 10 of the present embodiment can be used for a wide range of applications in which the properties of the polypropylene-based resin are utilized.

(Method of manufacturing transparent bottle)

In the present embodiment, the transparent bottle 10 is produced by an injection stretch blow molding method ("also referred to as a biaxial stretch blow molding method"). The injection stretch blow molding method includes an injection molding step of first producing a preform of a specific shape, and an extension blow molding step of producing a final resin molded article by performing stretch blow molding on the preform. (transparent bottle 10). In the injection stretch blow molding method, there is a hot parison type which directly performs stretch blow molding on the preform produced by the injection molding step, and a cold parison type which is in the injection molding step. The manufacture of the preform is carried out separately from the stretch blow molding step of the preform.

Since the polypropylene resin has high strength, no moisture absorption, and chemical resistance, the material of the transparent bottle 10 is relatively good. However, if the resin raw material is changed from a PET resin to a PP resin by using a PET transparent bottle manufacturing method which has been used as a transparent bottle having a relatively high transparency, it is impossible to produce a polypropylene having a desired transparency or strength. A transparent bottle made of resin.

The present inventors have made an effort to study a transparent bottle 10 using a polypropylene resin. The manufacturing method has been found to increase the transparency of the transparent bottle 10.

(First embodiment)

A method of manufacturing the transparent bottle 10 in the present embodiment will be described.

2 and 3 are views for explaining a method of manufacturing the transparent bottle 10 of the injection stretch blow molding method in the first embodiment. In the present embodiment, a case where the transparent bottle 10 is manufactured by a cold parison type will be described as an example.

2 is an explanatory view showing a step of producing a preform from a propylene resin composition as a resin material by an injection molding machine, and FIG. 3 is a preform obtained by using an injection molding step by an extension blow molding machine. An explanatory diagram of the steps of manufacturing the transparent bottle 10.

The cold parison type injection stretch blow molding method is performed by separately performing the production of the preform in the injection molding step from the stretch blow molding step of the preform.

First, the injection molding step will be described.

In the present embodiment, the injection molding machine 20 shown in Fig. 2 is prepared. The injection molding machine 20 includes an injection molding machine main body 21, an injection molding die 25 disposed at an end portion of the resin injection nozzle of the injection molding machine main body 21, a fixed die plate 26 fixed to the injection molding machine main body 21, and a configuration The fixed template 26 moves the moving template 27.

The injection molding machine main body 21 includes a heating cylinder 22, an extrusion screw 23 provided inside the heating cylinder 22, and a raw material hopper 24 that supplies the raw material to the extrusion screw 23.

The injection molding die 25 is disposed between the fixed die plate 26 and the moving die plate 27. A mold that exhibits the shape of the preform is provided in the injection molding die 25. Hole 28. The injection molding die 25 can be configured, for example, as a water-cooling type cooling mechanism.

In the injection molding machine 20 having the above-described configuration, the particulate material 30 of the polypropylene resin composition as the resin material is first placed in the raw material hopper 24 of the molding machine main body 21, and is heated and melted in the heating cylinder 22 to be produced. The resin 31 is melted. The molten resin 31 is sent to the side of the injection molding die 25 in accordance with the rotation of the extrusion screw 23. The molten resin 31 which is emitted from the injection molding machine main body 21 is introduced into the injection molding die 25 via the flow path portion of the fixed die plate 26. The molten resin 31 introduced into the injection molding die 25 is filled in the cavity 28.

The molten resin 31 filled in the cavity 28 of the injection molding die 25 is solidified from the surface by the cooling mechanism of the injection molding die 25, and is cooled to a temperature at which the shape of the preform can be maintained. Thereby, the molten resin 32 which exhibits the shape of the preform is formed in the cavity 28. Thereafter, the moving die plate 27 that has been injected out of the forming die 25 is detached from the fixed die plate 26, and the preform 28 is released from the cavity 28 of the injection molding die 25.

The conventional cold parison type injection stretch blow molding method is a method in which the preform is cooled in the injection molding die 25 to maintain a self-standing shape in order to shorten the cycle time of molding the preform (forming time of the preform). At the time point, the mold is removed from the injection molding die 25. The temperature of the preform when the injection molding die 25 is released is a temperature at which the preform can maintain its own shape, and is, for example, about 120 ° C or higher. Thereby, the production efficiency of the preform can be made good, so that it can be regarded as optimum.

However, in the present embodiment, the preforming system is in the cavity 28 of the injection molding die 25, and the preforming system is in the cavity 28 of the injection molding die 25, After cooling to 110 ° C or lower, preferably 100 ° C or lower, and more preferably 60 ° C or lower, the mold is released from the injection molding die 25 . In the following, the preform which has just been released from the injection molding die 25 is referred to as "preformed body during demolding" (in the present embodiment, "preformed body 33 at the time of demolding"). Here, the temperature of the preform is expressed by the surface temperature thereof, and the "temperature of the preform at the time of demolding" is the measurement result of the surface temperature of the preform 33 at the time of demolding immediately after the injection molding die 25 is released. .

That is, in the present embodiment, as described below, the preforming system is released from the injection molding die 25 after cooling to a temperature that does not reach the crystallization temperature of the resin raw material described below. Here, the "crystallization temperature" is a temperature at which the calorific value at the time of cooling the molten resin of the resin raw material reaches a peak by a differential scanning calorimeter (DSC) apparatus as described below.

The temperature of the molten resin 32 is lowered in the injection molding die 25, and the temperature of the preform 33 at the time of demolding is lowered, whereby the transparency of the transparent bottle 10 can be made higher. For example, when the temperature of the preform 33 at the time of demolding is 60° C. or lower, the body portion 11 of the transparent bottle 10 can be made even if the thickness of the main body portion 11 of the transparent bottle 10 is about 1.45 mm. The haze value is less than 5.0%. The reason for this is that the molten resin 32 (preformed body 33 at the time of mold release) is quenched in the injection molding die 25 to 60° C. or less by the cooling mechanism of the injection molding die 25, and therefore, a transparent bottle having particularly high transparency is obtained. In order to change the temperature of the molten resin 32 (preformed body 33 at the time of mold release) to 60 ° C or less in the injection molding die 25, for example, the cooling time in the injection molding die 25 can be about 2 to 5 minutes.

Thereafter, the cooling treatment at room temperature is further carried out. In the cooling treatment, the preform 33 is cooled to room temperature during demolding, and becomes a normal (non-heat) preform 35, and is stored for the next step, that is, the stretch blow molding step.

Next, the extension blow molding step will be described.

The preform 35 which is formed and stored in the above-described injection molding step is subjected to stretch blow molding in accordance with the stretch blow molding step shown in Fig. 3 .

The stretch blow molding machine 40 includes a heater 41, a blow molding die 42 having a cavity 43, and an extension rod 44. The cavity 43 is formed into the shape of the final product, that is, the transparent bottle 10.

First, as shown in (A), the preform 41 is reheated by the heater 41 of the stretch blow molding machine 40 to a temperature at which the shape of the preform 35 can be kept self-standing, for example, before and after 120 ° C. The heated preform 36 is heated. After the reheating treatment is completed, as shown in (B), the heated preform 36 is attached to the blow molding die 42. At this time, the portion of the preform 36 that is heated to be lower than the neck portion 12 is housed in the cavity 43 of the blow molding die 42.

Then, as shown in (C), the upper opening portion (as a portion of the neck portion 12) of the preform 36 after self-heating is inserted into the extension rod 44, and the heated preform 36 is extruded into the mold of the blow molding mold 42. Below the hole 43 (in the depth direction of the preform 36 after heating), it is longitudinally extended to form a longitudinally extending preform 37. The longitudinally extending preform 37 is extended as shown in (D) and extends longitudinally to the lower portion of the cavity 43 to form a longitudinally extending preform 38. The longitudinally extending preform 38 is blown by air from an air hole 45 provided at a side portion of the extension rod 44 as shown in (E), and is lateral (the side of the cavity 43) Direction) to extend (blow extension). The longitudinally and transversely extending preform 39 which is stretched by blow molding is brought into contact with the wall surface of the cavity 43 of the blow molding die 42, and is formed into a shape along the cavity 43.

(F) is a state in which the preform 30 is cooled in the cavity 43 to form the transparent bottle 10, and then the blow molding die 42 is opened to release the transparent bottle 10.

As such, in the present embodiment, the stretch blow molding step of the preform 35 can be transferred to the stretch blow molding step of the preform for the previous bottle manufacture. In the present embodiment, it is preferable that the temperature of the preform 35 is not excessively raised in the heating step of the preform 35 or the like. Preferably, the heating temperature of the preform 35 is not higher than the crystal melting temperature of the resin material, for example, 130 ° C or higher.

By performing the above-described stretching treatment (extension blow molding treatment), the wall thickness of the main portion (container body) of the preform 35 is reduced.

The transparent bottle 10 manufactured by the manufacturing method of the present embodiment is subjected to transparency measurement according to JIS K7105, and has the same degree as the transparent bottle made of PET, as described below (refer to Example 1 and Example 3 of Fig. 9). Thick and high transparency.

In the present embodiment, in the state in which the transparent bottle 10 is finally formed, the lower limit of the wall thickness of the main body portion 11 of the transparent bottle 10 can be set according to the required buckling strength of the transparent bottle 10, and for example, the buckling strength can be set to 100 N. The above wall thickness. As an example, the thickness of the main body portion 11 of the transparent bottle 10 can be, for example, 0.7 or more.

Moreover, the upper limit of the wall thickness of the main body portion 11 of the transparent bottle 10 can be based on the transparent bottle 10 is set to have transparency required. For example, the haze value of the main portion of the transparent bottle 10 may be 6% or less, more preferably 5% or less.

Further, the ratio of the equivalent diameter (equivalent diameter) to the height of the main body portion 11 of the transparent bottle 10 can be, for example, 1:0.5 to 1:5. The transparent bottle 10 can have a capacity of, for example, 100 ml or more and 2000 ml or less, preferably 200 or more and 500 ml or less. By making such a configuration, the same strength as that of the above can be secured.

Further, the strength or transparency required for the transparent bottle 10 can be appropriately set depending on the purpose, and the shape or size of the transparent bottle 10 can be appropriately changed depending on the required strength or transparency.

(Second embodiment)

Also in the present embodiment, as in the first embodiment, a case where the transparent bottle 10 is manufactured by a cold parison type will be described as an example. In the method of manufacturing the transparent bottle 10 of the present embodiment, after the injection molding step, the method further includes a quenching step of quenching the preform 33 when the mold is released from the injection molding die 25.

The quenching step includes a process of cooling the preform 33 by spraying cooling water, or immersing it in ice water, or forcibly cooling it by cold air, and cooling it more rapidly than usual in room temperature. Also in the present embodiment, the preform is released from the injection molding die 25 after being cooled in the cavity 28 of the injection molding die 25 to 110 ° C or lower, preferably 100 ° C or lower. In other words, in the present embodiment, as described below, the preform is cooled to a temperature that does not reach the crystallization temperature of the resin material, and then released from the injection molding die 25.

Thereafter, in the quenching step, the preform 33 at the time of demolding can be cooled to, for example, 80 ° C or lower, more preferably 60 ° C or lower by quenching treatment. Further, in the present embodiment, the preform may be cooled to a temperature of 60 ° C or lower in the cavity 28 of the injection molding die 25, and then subjected to rapid cooling in the quenching step to pre-release the mold. The molded body 33 is cooled to a lower temperature, for example, about room temperature.

In the present embodiment, the step of stretch blow molding may be the same as that described in the first embodiment.

In the present embodiment, the shape, size, and the like of the transparent bottle 10 may be the same as in the first embodiment in a state in which the transparent bottle 10 is finally formed.

The transparent bottle 10 manufactured by the molding method of the present embodiment is subjected to transparency measurement according to JIS K7105, and as described below (see Example 2 of Fig. 9), has the same thickness and thickness as that of the transparent bottle made of PET. High transparency. Obviously, the transparency of the transparent bottle 10 can be made better by performing the quenching step on the preform 33 at the time of demolding.

(Third embodiment)

In the present embodiment, the transparent bottle 10 will be described by taking a case where the preform produced in the injection molding step is directly subjected to stretch blow molding immediately. In the present embodiment, the difference from the first embodiment and the second embodiment is that the transparent bottle 10 is not subjected to the cooling treatment at room temperature after the injection molding step.

Fig. 4 is a view for explaining a method of manufacturing the transparent bottle 10 of the injection stretch blow molding method in the third embodiment. In FIG. 4, the same components as those shown in FIGS. 2 and 3 are denoted by the same reference numerals, and the description thereof is omitted. Description.

The cold parison type injection stretch blow molding method of the embodiment described above completely separates the manufacture of the preform 35 in the injection molding step from the stretch blow molding step of the preform 35. Therefore, the preform 35 is temporarily cooled to room temperature after being released from the injection molding die 25, and thereafter, reheating is performed from room temperature in the stretch blow molding step to the vicinity of the softening temperature of the preform 35.

On the other hand, in the injection stretch blow molding method of the present embodiment, the stretch blow molding step is performed by the heat of fusion of the resin applied in the injection molding process step. In other words, in the injection stretch blow molding method of the present embodiment, the preform which has been released from the injection molding die 25 of the injection molding machine 20 is directly subjected to stretch blow molding by the stretch blow molding machine 60 as it is. The injection stretch blow molding method in the present embodiment is carried out in the same manner as the hot parison type injection stretch blow molding method. As shown in FIG. 4, the stretch blow molding machine 60 includes a fixing portion 66, a heater 61, and an extension rod 64.

First, the conventional hot parison type injection stretch blow molding method will be described.

Referring to Fig. 4, previously, in the stretch blow molding step, the preform formed by the injection molding machine 20 is cooled to a state in which the shape as the preform can be self-supporting without being deformed, and the self-ejection molding die 25 demoulding. Then, the preform which is released from the injection molding die 25 is attached to the stretch blow molding machine 60 without being cooled, and the additional heat treatment and the stretch blow molding process are continuously performed. In the case of the injection stretch blow molding method using the hot parison type, the temperature of the preform immediately after demolding is exhausted. The stretch blow molding is performed directly at a high level, whereby the addition of heat to the additional heat treatment is reduced, and the energy use efficiency is improved.

Next, the injection stretch blow molding method in the present embodiment will be described. In addition, in FIG. 4, the preform which has just been released from the injection molding die 25 of the injection molding machine 20 is shown as the preform 55 at the time of mold release.

In the present embodiment, as in the case of the first embodiment and the second embodiment, the preform is cooled to 110 ° C or lower, preferably 100 ° C or lower, in the cavity of the injection molding die 25 . Further, after the temperature is preferably 60 ° C or lower, the injection molding die 25 is released from the mold. In other words, in the present embodiment, as described below, the preform is released from the injection molding die 25 after being cooled to a temperature at which the crystallization temperature of the resin material is not reached.

When the mold is released in this manner, the preform 55 is immediately placed on the fixing portion 66 of the stretch blow molding machine 60 (Fig. 4(a)), and is heated by the heater 61 (Fig. 4(b) ). The heated preform 56, which has been heated to a specific temperature, is subjected to 2-axis stretch forming by the stretching rod 64 and the air from the air holes 65 (Fig. 4 (c)). Further, the two-axis extension molding can be set in the same order as described with reference to (C) to (E) of Fig. 3 . The preform 59 formed by the two-axis stretch is cooled by the stretch blow mold 62 of the stretch blow molding machine 60, and is released from the mold to form the transparent bottle 10 ((d) of Fig. 4).

The conventional hot parison type injection stretch blow molding method considers the energy use efficiency so that the temperature of the preform at the time of demolding can be maintained at a shape of, for example, 120 ° C or more. However, in the present embodiment, although the energy use efficiency is slightly inferior, the temperature of the preform 55 at the time of demolding is 110 ° C or lower, preferably 100 ° C or lower, and more preferably 60 ° C or lower. borrow Thus, a transparent bottle 10 having a higher transparency can be obtained.

The transparent bottle 10 produced by the molding method of the present embodiment has a wall thickness and a high transparency similar to those of a transparent bottle made of PET after being measured in accordance with the transparency of JIS K7105.

On the other hand, as described below (refer to the comparative example of Fig. 9), the temperature of the preform at the time of demolding is a transparent bottle manufactured at a temperature of 116 ° C or higher, i.e., 116 ° C to 120 ° C, which is a crystallization temperature of the resin material. Become the result of lower transparency.

According to these results, even when the same polypropylene resin composition is used as the resin material, the preform is cooled to a specific temperature in the injection molding die 25, and then released from the injection molding die 25. Thereby, a transparent bottle having a high transparency can be manufactured.

(crystallization temperature of polypropylene resin and cooling temperature of preform)

A study was conducted to clarify the relationship between the cooling temperature of the preform and the transparency of the obtained resin molded article.

First, the crystallization temperature of the molten resin (melted PP resin) of the polypropylene resin (PP resin) which is the resin raw material of the transparent bottle 10 is measured and analyzed by a differential scanning calorimeter (DSC) apparatus, and Crystal melting temperature. The results of differential scanning calorimetry (DSC) are shown in Figure 5. In addition, in FIG. 5, the graph of the differential scanning thermal analysis result of the molten resin cooling curve and the crystal melting curve twice is shown superimposed.

In Fig. 5, the graph shown in Fig. 5 is a graph showing the crystallization temperature distribution (melted resin cooling curve) of the molten PP resin, which is shown by the height of the heat generation of 0 mW in the DSC. Molten PP resin exhibits a large temperature of heat generation The area is approximately 129 ° C to 111 ° C. This region is referred to as a temperature region of a crystallized region or a crystal growth region of the PP resin (referred to as a "crystallization temperature region"), and a crystal region is formed from the molten PP resin, or a crystal region in which the generated crystallites are crystal grown. Further, the peak value of the calorific value was 116 °C. Here, the temperature at which the peak value of the calorific value is referred to as "crystallization temperature". When the molten PP resin is not more than 110 ° C in the crystallization temperature region, crystallization or crystal growth is less likely to occur, and the uncrystallized portion is almost directly cured (glass state).

On the other hand, the melting temperature distribution (crystal melting curve) caused by the heating of a part of the crystallized resin after curing is represented by (B), which is higher than the calorific value of 0 mW of FIG. 5 and higher than the lower side (endothermic region). The curve is roughly convex. From the DSC measurement results of Fig. 5, it was judged that the melting temperature of the crystal had a peak near 130 ° C to 160 ° C, and became a broad curve as compared with the molten resin cooling curve, and the peak was located at around 150 ° C. This region is a melting temperature region of the PP resin, and when the PP resin reaches 130 ° C or higher, the crystallized or solidified portion is melted to become a molten resin. Thus, it was judged that the crystallization temperature region (crystal growth region) of the PP resin deviated from the melting temperature region, and the crystallization temperature region was higher than the melting temperature region.

Next, the temperature change of the preform in each step in the extension blow molding process of the cold parison type extrusion blow molding method is shown. Fig. 6 is a view showing changes in temperature of a PP resin or a molded article thereof in a cold parison type injection stretch blow molding method. Hereinafter, description will be made also with reference to FIGS. 2 and 3.

As shown in Fig. 6, in the injection molding machine 20, when the preform 35 is molded from the PP resin, the pelletized or powdered PP resin at room temperature is heated and melted in the heating cylinder 22 of the injection molding machine body 21. After the kneading, the injection molding temperature t _{1 is} reached, and the injection molding die 25 is injected. The injected molten resin 32 is introduced into the cavity 28 of the shape of the preform 35 in the injection molding die 25, and is cooled in the cavity 28 to reach a temperature t ₂ , which is a preform when the surface is sufficiently cured. Body 33 (the above steps are indicated by "(A)" in the figure). In the present embodiment, the surface temperature t ₂ when the preform 33 is released from the injection molding die 25 at the time of mold release is 110 ° C or lower, preferably 100 ° C or lower, and more preferably 60 ° C or lower.

In the cold parison type extrusion stretch blow molding method described in the first embodiment, the demolded body 33 is released from the injection molding die 25 when the surface is sufficiently cured, and is taken along the line from FIG. The position of the solid line temperature t ₂ is cooled toward the solid line a which is gently inclined to the lower right side, and is formed into a preform 35 at room temperature (the above step is indicated by "(B)" in the figure).

Then, when it is required to manufacture a transparent bottle from the preform, as described with reference to Fig. 3, the room temperature preform 35 is attached to the stretch blow molding machine 40 to perform heating, longitudinal stretching, and blow molding (lateral). Extend and manufacture a transparent bottle 10. At this time, the preform 35 is heated to the stretch blow molding temperature t ₃ as shown by the temperature distribution of the solid line of the trapezoid on the right side in FIG. 6, and is subjected to stretch blow molding, and then cooled to form the transparent bottle 10. Further, the stretch blow molding temperature t ₃ is less than 130 ° C (the above step is indicated by "(C)" in the figure).

The position of the temperature t ₂ from the solid line shown in Fig. 6 toward the obliquely lower right side is indicated by the second embodiment, and it is shown that the preform 33 is quenched to room temperature when the mold is released by ice water. An example of additional quenching treatment.

Then, it represents an extension of the hot parison type injection stretch blow molding method. The temperature change of the preform in each step of the plastic forming process. Fig. 7 is a view showing changes in temperature of a PP resin or a molded article thereof in a hot parison type injection stretch blow molding method. Hereinafter, description will be made also with reference to FIG. 4.

As shown, in the formula of the emitted hot parison blow molding method 7 extends, and injection blow-molding method of a cold parison type that extends in the same manner, by injection molding temperature t ₁ is emitted to the melt in the injection molding die 25 The resin 32 is introduced into the cavity of the shape of the preform 35 in the injection molding die 25. Thereafter, as shown by a broken line b in Fig. 7, in the injection molding blow molding method of the hot parison type, in the injection molding die 25, the preform is cooled to a stretch blow molding temperature t ₃ at the time of demolding. The mold release was carried out at the same time point (about 120 ° C). When demolded, the preform 55 is directly attached to the stretch blow molding machine 60 as shown in Fig. 4, heated to a stretch blow molding temperature t ₃ , longitudinally stretched, blow stretched, and formed into a transparent shape. bottle.

On the other hand, in the injection stretch blow molding method of the third embodiment, the molten resin 32 introduced into the cavity of the shape of the preform 35 in the injection molding die 25 is cooled in the cavity of the injection molding die 25, Further, the mold is released from the injection molding die 25 at a temperature t ₂ (lower than the temperature t _{4 of the} previous hot parison) (the above step is indicated by "(A)" in the figure). Thereafter, the preform 55 is directly attached to the stretch blow molding machine 60 at the time of demolding, heated to the stretch blow molding temperature t ₃ , and the extension (longitudinal extension) and blow extension (lateral extension) of the extension rod are performed. A transparent bottle 10 is produced (the above steps are indicated by "(C)" in the figure) (refer to Fig. 4).

In the injection stretch blow molding method described in the third embodiment, the surface temperature t ₂ when the preform 55 is released from the injection molding die 25 during demolding is 110 ° C or lower, preferably 100 ° C or lower, and further Good is below 60 °C.

This temperature distribution is indicated by the solid line a.

Fig. 8 is a view showing the cold parison type injection stretch blow molding method according to the first embodiment and the conventional hot parison type injection stretch blow molding method in the injection molding die 25 of the injection molding machine 20, which is cooled. A graph of temperature change in the vicinity of the crystallization temperature region (crystal growth region) of the PP resin. The horizontal axis represents about 30 seconds on the time axis, and the vertical axis represents the temperature of the resin (or the surface of the molded article thereof) of 150 ° C to 90 ° C. In addition, the temperature region (111 ° C to 129 ° C) in the vicinity of the crystallization temperature region (crystal growth region) described with reference to Fig. 5 is indicated by oblique lines (referred to as "C" in the figure).

The solid line (A) of Fig. 8 shows an example of the temperature change of the molten resin 32 (PP resin) and the preform 33 at the time of demolding in the cold parison type extrusion blow molding method according to the first embodiment.

Here, the molten resin 32 cooled to 150 ° C or lower in the injection molding die 25 is directly cooled to the temperature t ₂ (100 ° C), and then released from the injection molding die 25 (time b). Then, at the time of demolding, the preform 33 is cooled to 90 ° C or lower.

Here, the temperature t ₂ of the preform 33 at the time of demolding immediately after demolding is 100 ° C and 110 ° C or less, and the resin temperature at the time of demolding (the surface temperature of the preform 33 at the time of demolding) has become crystallized. Temperature.

As shown by the solid line (A) in Fig. 8, in the injection stretch blow molding method, the molten resin 32 is rapidly cooled in the injection molding die 25, but after the ejection molding die 25 is released (after time b), the temperature The reduction becomes extremely slow. Therefore, as described in the above embodiments, the molten resin can be used The 32 (preform) is cooled in the injection molding die 25 to a temperature that is less than the crystallization temperature, more preferably not in the crystallization temperature region, and the time during which the molten resin 32 stays in the crystallization temperature region becomes extremely short. It is considered that the preform 33 is solidified in a state in which crystals are generated, in particular, crystal growth is small, during the mold release which is cooled to a temperature at which the crystallization temperature is not reached in the injection molding die 25. When the mold is released, the resin in the preform 33 is substantially solidified, and almost no more crystallization or crystal growth is caused.

Further, the temperature of the preform 33 after the mold release is slightly increased after the mold release, but it is considered that the reason is that in the present embodiment, since the resin temperature of the surface of the preform 33 at the time of demolding is measured, The heat inside the preform 33 was released to the surface at the time of demolding after demolding, and the surface temperature was slightly raised. The release temperature of the preform 33 at the time of demolding is also considered to affect the temperature rise. For example, the resin temperature at the time of demolding (the surface temperature of the preform 33 at the time of demolding) is preferably about 100 ° C or less. . In this manner, the resin inside the preform 33 at the time of demolding immediately after demolding can be made almost at most 110 °C. With such a configuration, the preform 33 is cooled to room temperature at the time of demolding, and does not reach 110 ° C or higher.

As explained with reference to Fig. 5, once the temperature is lowered to around room temperature, the cured (after freezing) PP resin does not cause melting of the crystal in the region where the melting temperature is not reached (130 to 160 ° C). Therefore, it is considered that the molten resin is not present in the region where the melting temperature is not reached (130 to 160 ° C), and therefore, the generation or growth of crystals is not caused. In the present embodiment, the treatment temperature in the stretch blow molding may be, for example, about 120 ° C or so and is not set to 130 ° C or higher. Therefore, it does not cause the generation or growth of crystals in the stretch blow molding. The molded body is directly stretched in a state where the crystals are less or crystallized, and the transparent body 10 is formed. In this way, the transparent bottle 10 in the present embodiment becomes a container having extremely high transparency.

On the other hand, the broken line (B) of Fig. 8 shows an example of the temperature change of the molten resin (PP resin) in the injection stretch blow molding method of the prior hot parison type and the preform at the time of demolding.

Here, in the same manner as the cold parison type extrusion blow molding method of the solid line (A), the PP resin cooled to 150 ° C in the injection molding die 25 is further cooled to reach the temperature t ₄ (120). At °C), the molding die 25 is released from the mold (time a). The preform which was demolded during demolding was directly mounted in the stretch blow molding machine 60 (time c).

As described above, previously, in order to achieve the energy and time saving of the heating in the stretch blow molding in the next successive step, the preform is cooled to a degree that can be self-supporting without being deformed as a shape of the preform. In the state, the injection molding die 25 is released from the mold, and the temperature t ₄ of the preform at the time of demolding is about 120 ° C or more.

Further, the broken line (B) of Fig. 8 will be further described. When the mold is released from the injection molding die 25 at a temperature t ₄ of about 120 ° C (in the crystallization temperature region), the preform is placed on the stretch blow molding machine 60. (Fig. 3 (a)), heating is performed by the heater 61 (Fig. 3 (b)). The preform 56 (time d) which is heated to a specific temperature t ₃ is subjected to 2-axis stretch forming by stretching of the rod and air (Fig. 3 (c)). Further, the two-axis extension molding can be the same as that described with reference to FIGS. 3(B) to (F). The preform formed by the 2-axis stretch molding is cooled (time e) by the stretch blow mold 62 (Fig. 3 (d)), and is released into a transparent bottle after demolding.

In the conventional hot parison type injection stretch blow molding method, the time from the time of demolding to the formation of a transparent bottle by stretch blow molding is approximately 30 seconds. In the injection molding and blow molding method of the conventional hot parison type, the molten resin (PP resin) melted in the injection molding die 25 is at a temperature of a crystallization temperature region of a temperature of about 129 ° C or lower, and crystal formation and crystal growth are performed. Start. In addition, the partially crystallized PP resin is directly released from the injection molding die 25 while remaining in the crystallization temperature region, and is directly subjected to stretch blow molding after being released as a preform. Therefore, the PP resin stays in the crystallization temperature region for 20 seconds or more, and during this period, crystal formation and crystal growth are performed. If crystal formation, particularly crystal growth, is carried out before the resin is subjected to extension cooling, the transparency of the transparent bottle formed by stretch blow molding tends to be deteriorated due to the difference in refractive index between the crystal portion and the amorphous portion. In this respect, the method for producing a transparent bottle of a PP resin under the above-described conventional hot parison type injection stretch blow molding method is compared with the cold parison type injection stretch blow molding method of the present embodiment. Poor.

On the other hand, although not shown here, in the injection stretch blow molding method of the third embodiment, the molten resin 32 (preform) is cooled in the injection molding die 25 to a temperature at which the crystallization temperature is not reached. Temperature (below 110 ° C). As described above, the molten resin 32 is rapidly cooled in the injection molding die 25. Therefore, when the molten resin 32 (preform) is rapidly lowered in the injection molding die 25 to a crystallization temperature (110 ° C or lower), the crystal formation and the crystal growth are stopped, and the preform is released at the time of demolding. 55 is demolded. According to this configuration, even if the preform 55 is released and deformed by the stretch blow molding machine 60, the preform 55 is not heated and formed as in the prior hot draft. Crystal formation and crystal growth of the plastic molding method.

When the temperature t ₂ of the preform 55 at the time of demolding is 110° C. or lower, preferably 100° C. or lower, and more preferably 60° C. or lower, the resin in the preform 55 is released due to freezing at the time of demolding. Curing does not cause crystallization or growth, and the resulting transparent bottle 10 can be a container having high transparency.

Further, although not shown in the drawings, in the cold parison type extrusion blow molding method, the temperature t ₄ of the temperature in the crystallization temperature region is, for example, about 120 ° C (in the crystallization temperature region). When the injection molding die 25 is released from the mold release, the preform is retained in the crystallization temperature region for a long period of time at this temperature. Therefore, the formation of crystals and the growth of crystals will occur during this period. If crystal formation, particularly crystal growth, is carried out before the resin is subjected to extension cooling, the transparency of the transparent bottle formed by stretch blow molding tends to be deteriorated due to the difference in refractive index between the crystal portion and the amorphous portion.

(Example)

In the first to third embodiments, the production method of the injection stretch blow molding of the transparent bottle 10 of the present embodiment is shown. In each of Examples 1 to 3, the method of cooling the preform was changed, and a plurality of transparent bottles having different wall thicknesses were produced, and the haze value was measured for each.

Example 1 is a transparent bottle 10 manufactured by a cold parison injection stretch blow molding process. Corresponding to the manufacturing order described in the first embodiment.

As a polypropylene resin composition as a resin raw material, propylene-ethylene is used. Random copolymer (J-721GR (trade name) manufactured by Prime Polymer Co., Ltd.). No additives such as additives are added to J-721GR. The injection molding temperature (cylinder portion temperature) was set to 220 ° C, and the temperature of the cooling water of the injection molding die 25 was set to 15 ° C. The injection molding die 25 is held for approximately 15 seconds, and after the surface temperature of the preform is cooled to 100 to 110 ° C, the molding die 25 is released from the molding die 25 . The preform 33 was allowed to cool at room temperature when demolded.

The blow molding temperature in the stretch blow molding was 120 ° C, and after the blow molding, the transparent bottle 10 was released from the mold and allowed to cool at room temperature. The shape of the transparent bottle 10 is a substantially cylindrical shape having a shape shown in Fig. 1 and having a capacity of 200 ml or 500 ml.

The wall thickness of the transparent bottle 10 is approximately 0.7 to 1.37 mm. The relationship between the wall thickness (mm) of each transparent bottle 10 and the haze value (%) is shown in FIG. The result of Example 1 is indicated by the ◆ (black diamond) mark (a).

The transparent bottle 10 has a haze value of a minimum of 1.34% (wall thickness 0.7 mm) to a maximum of 5.74% (wall thickness 1.37 mm). The approximate straight line showing the relationship between the wall thickness d mm and the haze value of the main body portion 11 of the transparent bottle 10 obtained by the production method of Example 1 is indicated by a solid line. Here, the approximate straight line is set to t mm in the wall portion of the main body portion 11 according to the least square method, and h@5.80*t-2.55 (R ² =0.89) when the haze value of the main body portion 11 is h%. Said.

Further, in the manufacturing method of the first embodiment, the haze value of the main body portion 11 can be made less than 5% in the range of the wall thickness t of the main body portion 11 of the transparent bottle 10 of 0.7 mm ≦ t ≦ 1.3 mm.

In the second embodiment, the same resin material as in the first embodiment was used, and the preform 33 was immersed in ice water at the time of demolding and quenched to 60 ° C or lower at room temperature. The transparent bottle 10 was produced in the same manner as in Example 1 except that the preform 33 was allowed to cool at room temperature when the mold was released from the injection molding die 25 in the first embodiment.

The wall thickness of the transparent bottle 10 is approximately 1.08 to 1.24 mm. In Fig. 9, the relationship between the wall thickness (mm) of each transparent bottle 10 and the haze value (%) is shown. The result of Example 2 is represented by a □ (hollow quadrilateral) mark (b).

The transparent bottle 10 has a haze value of a minimum of 3.33% (wall thickness 1.2 mm) to a maximum of 3.62% (wall thickness 1.24 mm). In Example 2, a transparent bottle 10 having a higher wall thickness and higher transparency was obtained as compared with Example 1.

In the third embodiment, the same resin material as in the first embodiment is used, and the surface temperature of the preform is cooled to 60° C. or less after being held in the injection molding die 25 for about 120 seconds, and then the mold is removed from the injection molding die 25 to A transparent bottle was produced in the same manner as in Example 1.

The wall thickness of the transparent bottle 10 is approximately 1.15 to 1.44 mm. In Fig. 9, the relationship between the wall thickness (mm) of each transparent bottle 10 and the haze value (%) is shown. The result of Example 3 is represented by a Δ (hollow triangle) mark (c).

The transparent bottle 10 has a haze value of 2.75% (wall thickness 1.15 mm) to a maximum of 4.54% (wall thickness 1.44 mm). In Example 3, a transparent bottle 10 which was substantially the same as Example 2 was obtained, and the transparency was higher than that of Example 1 as compared with Example 1.

In Fig. 9, after the results of Example 2 and Example 3 are collected, the approximate straight line of the haze value is indicated as a broken line. Here, the approximate straight line is set to t mm by the minimum flat method, and when the haze value of the main body portion 11 is h%, h≒4.48×t−1.92 (R ² =0.70). Said.

Further, by the manufacturing method of the second embodiment or the third embodiment, the haze value of the main body portion 11 can be made not to be within the range of the wall thickness t of the main body portion 11 of the transparent bottle 10 of 0.7 mm ≦ t ≦ 1.45 mm. Up to 5%.

As a comparative example, a transparent bottle was produced by the same hot preform type injection stretch blow molding method using the same resin material as in Example 1. Here, the injection molding temperature (cylinder temperature) of the preform is 204 ° C, and the temperature (surface temperature) of the preform immediately after the mold is released from the injection molding die 25 is 116 to 120 ° C, and the stretch blow molding temperature is extended. It is implemented at 120 °C.

The wall thickness of the transparent bottle is approximately 0.73 to 0.84 mm. In Fig. 9, the relationship between the wall thickness (mm) of each transparent bottle 10 and the haze value (%) is shown. The result of the comparative example is represented by × mark (d).

The transparent bottle has a haze value of 10.31 (wall thickness 0.76 mm) to 12.1 (wall thickness 0.73 mm)%. In the method for producing a transparent bottle of the comparative example, the mold release temperature of the injection molding die 25 at the time of manufacture of the preform is a temperature in the crystallization temperature region, so that the haze value becomes extremely high. (10% or more).

As shown in Fig. 9, according to the method for producing the transparent bottle 10 of the present embodiment, it is understood that the haze value linearly increases as the thickness of the main body portion 11 of the transparent bottle 10 increases. Further, the results of Example 2 and Example 3 shown by broken lines are shown by a straight line showing a haze value of the same wall thickness as a result of Example 1 shown by a solid line. From the above, it can be seen that the transparency can be made better by rapidly bringing the preform to a temperature of 60 ° C or lower at the time of demolding.

In order to achieve the same degree of transparency as the PET transparent bottle, it is preferred to have a haze value of 5% or less or less than 5%.

For example, in the case of using the production method of the first embodiment, the haze value can be made less than 5% by making the thickness of the transparent bottle 10 1.3 mm or less.

Further, in the case of the first embodiment, when the temperature of the preform 33 at the time of demolding is set to be lower than 60 ° C (Example 3), or in addition, the cooling treatment (quenching treatment) is additionally performed. When the temperature of the mold preform 33 is 60 ° C or lower (Example 2), the haze value in the same wall thickness is reduced by about 1.0 to 0.5% as compared with Example 1. It can be understood that the transparency of the transparent bottle 10 can be improved by rapidly cooling the preform after the injection molding to, for example, 60 ° C or lower. In the case of using the production method of Example 2 or Example 3, the haze value may be less than 5% by making the wall thickness of the transparent bottle 1.45 mm or less.

As described above, according to the method for producing the transparent bottle 10 of the present embodiment, it is possible to manufacture a wall thickness of 0.7 to 1.3 mm, or 0.7 to 1.45 mm, preferably 0.85 to 1.45 mm, and more preferably 1.0 to 1.45 mm. Transparent bottles with a haze value of 5% or less or less than 5%. Further, according to the method for producing a transparent bottle of the present invention, a transparent bottle having a haze value of less than 2% in a region having a wall thickness of 0.7 to 1.0 mm, preferably 0.7 to 0.8 mm, can be produced. Furthermore, the transparent bottle of the present invention can have a haze value of 1.5% or more and less than 2% in a region having a wall thickness of 0.7 to 1.0 mm, preferably 0.7 or more and less than 0.8 mm, and a wall thickness of 1.0 to 1.45 mm. Or the area of 1.0 to 1.3 mm has a haze value of less than 5% and 2.5% or more.

(buckling strength of transparent bottle)

The wall thickness of the body portion 11 of the transparent bottle 10 is also related to the strength of the transparent bottle 10. In general, a buckling strength test is carried out as a test for measuring the strength of a container (especially the strength of a PET bottle). Also for the transparent bottle 10 of the embodiment, This buckling strength test was employed. The buckling strength test was carried out by using a compression tester (Autograph AG-1 manufactured by Shimadzu Corporation) at a test temperature of 30 ° C and compressing at a speed of 20 mm/min from the top of the transparent bottle 10 until the buckling, which is the largest at this time. Strength as buckling strength.

Fig. 10 is a view showing the test results of the buckling test of the transparent bottle produced by the cold parison injection stretch blow molding of the above-mentioned Example 1. As shown in Fig. 10, the buckling strength of the transparent bottle becomes stronger as the wall thickness of the container becomes thicker, and conversely, becomes smaller as the wall thickness becomes thinner. Further, the same results were obtained for the transparent bottles 10 produced in Example 2 and Example 3.

In general, in a container in which a liquid such as a beverage or a cosmetic product is used as a content, a buckling strength of 100 N or more is required. This is because the buckling strength of 100 N or more is required as the strength against deformation of the container when the container is loaded in a corrugated cardboard box or the like.

As is clear from the results of Fig. 10, for example, in order to make the buckling strength 100 N or more, the thickness of the transparent bottle 10 can be made 0.7 mm or more.

Further, in the buckling strength test, a transparent bottle 10 having a volume of 500 ml and a ratio of the equivalent diameter to the height of the main body portion 11 of 1:3 is used, but if the capacity is 100 ml or more and 2,000 ml or less, Further, the ratio of the equivalent diameter to the height of the main body portion 11 is 1:0.5 to 1:5, so that the same strength can be ensured by the same wall thickness. In this manner, a transparent bottle of the present invention which satisfies the buckling strength even without forming a strength reinforcing portion such as a rib can be produced. Needless to say, a container having a strength reinforcing portion such as a rib or an embossed pattern is more preferable.

As is apparent from the results of the first to third embodiments described above, according to the method for producing the transparent bottle 10 of the present embodiment, for example, the use can be performed by injection. The preform produced by the step is rapidly changed to 110 ° C or lower, more preferably 100 ° C or lower, and the haze of the main body portion 11 of the transparent bottle 10 having a wall thickness of about 1.33 mm of the main body portion 11 is less than 5%. To maintain good transparency. Further, for example, the haze value of the main body portion 11 of the transparent bottle 10 having the wall thickness of the main body portion 11 of about 1.45 mm can be made short by changing the preform produced by the injection molding step to 60 ° C or lower. 5% to maintain good transparency.

Further, as a result of measuring the buckling strength of the transparent bottle 10 produced in the first to third embodiments and FIG. 10, when the wall thickness of the main body portion is 0.7 mm or more, the buckling strength is 100 N or more, preferably If the wall thickness of the main body portion is 0.85 mm or more, the unevenness is considered, and the buckling strength is also 100 N or more, so that a transparent bottle can be manufactured.

Therefore, in the present embodiment, in order to make the buckling strength 100 N or more and the haze value of the main body portion 11 of the transparent bottle 10 is less than 5%, the preform produced by the injection molding step is rapidly changed. When the temperature is 110 ° C or lower, more preferably 100 ° C or lower, the thickness of the main body portion 11 of the transparent bottle 10 can be 0.7 mm ≦ t ≦ 1.33 mm, and the preform produced by the injection molding step can be rapidly formed. When the temperature is 60 ° C or lower, the thickness of the main body portion 11 of the transparent bottle 10 can be made 0.7 mm ≦ t ≦ 1.45 mm. The container body 11 can be used as a container for replacing a transparent bottle made of PET by making the haze value of the main body portion 11 of the transparent bottle 10 less than 5%.

Further, the transparent bottle 10 of the present embodiment has a capacity of, for example, 100 ml or more and 2,000 ml or less, and the ratio of the equivalent diameter to the height of the main body portion is 1:0.5 to 1:5.

According to the transparent bottle of the present embodiment and the method for producing the same, a transparent bottle having high transparency and maintaining mechanical strength can be provided.

Furthermore, the present invention also includes the following embodiments.

(1) A method for producing a transparent bottle, which is a resin bottle which comprises a propylene homopolymer and/or a propylene copolymer as a resin raw material by an injection stretch blow molding method. Raw material, and the capacity is 100 ml or more and 2,000 ml or less, the ratio of the equivalent diameter to the height of the main body is 1:0.5 to 1:5, the wall thickness of the main body is 0.7 to 1.3 mm, and the haze value of the main body is not reached. 5%, and the buckling strength of the main body portion is 100 N or more, and the method for producing the transparent bottle includes: an injection molding step of cooling to 110 ° C or lower in the injection molding die to produce a preform; and stretch blow molding In the step, the preform is subjected to stretch blow molding to produce a transparent bottle.

(2) A method for producing a transparent bottle, which is a resin bottle which uses a propylene homopolymer and/or a propylene copolymer as a raw material resin as a resin composition by an injection stretch blow molding method. The raw material has a capacity of 100 ml or more and 2,000 ml or less, the ratio of the equivalent diameter to the height of the main body portion is 1:0.5 to 1:5, the wall thickness of the main body portion is 0.7 to 1.45 mm, and the haze value of the main body portion is not reached. 5%, and the buckling strength of the main body portion is 100 N or more, and the method for producing the transparent bottle includes an injection molding step in which the hot preform is directly released from the injection molding die in the injection molding step. The preform is formed by quenching to 60 ° C or lower, and a stretch blow molding step of stretching and blow molding the preform to produce a transparent bottle.

(3) The method for producing a transparent bottle according to (1) or (2), wherein the injection stretch blow molding method is a cold parison injection stretch blow molding method.

(4) The method for producing a transparent bottle according to any one of (1) to (3), wherein the injection molding step cools the preform to 60 ° C or lower in the injection molding die.

(5) The method for producing a transparent bottle according to any one of (1) to (4) wherein at least one of the propylene homopolymer and/or the propylene copolymer is produced from a vegetable material.

(6) A transparent bottle which uses a propylene homopolymer and/or a propylene copolymer as a resin raw material as a raw material, and has a capacity of 100 ml or more and 2,000 ml or less, and an equivalent diameter and a height of the main body portion. The ratio is 1:0.5 to 1:5, the wall thickness of the main body is 0.7 to 1.45 mm, the haze value of the main body portion is less than 5%, and the buckling strength of the main body portion is 100 N or more.

(7) The transparent bottle according to (6), wherein at least one of the above propylene homopolymer and/or propylene copolymer is produced from a vegetable material.

The preferred embodiments and examples of the present invention have been described in detail above, but the present invention is not limited to the specific embodiments and examples described above, and various modifications may be made within the scope of the spirit of the invention described in the claims. ,change.

The present application is based on the priority of Japanese Patent Application No. 2011-245901, filed on Jan.

10‧‧‧Transparent bottles

11‧‧‧ Main body

12‧‧‧ neck

13‧‧‧ shoulder

14‧‧‧ bottom

15‧‧‧Intersection of the main body 11 and the shoulder 13

16‧‧‧Intersection of the main body 11 and the bottom 14

17‧‧‧ Main body

20‧‧‧ Injection molding machine

21‧‧‧Injection molding machine body

22‧‧‧heating cylinder

23‧‧‧Extrusion screw

24‧‧‧Material hopper

25‧‧‧ Injection molding die

26‧‧‧Fixed template

27‧‧‧Mobile template

28‧‧‧ cavity

30‧‧‧Particles of polypropylene resin composition

31‧‧‧ molten resin

32‧‧‧Molded resin in the shape of preform

33‧‧‧Preformed body during demolding

35‧‧‧Normal (non-thermal) preforms

36‧‧‧heated preforms

37‧‧‧Longitudinal extension preforms

38‧‧‧Longitudinal extension preforms

39‧‧‧Longitudinal extension preforms stretched by blow molding

40‧‧‧Extended blow molding machine

41‧‧‧heater

42‧‧‧Blow molding die

43‧‧‧ cavity

44‧‧‧Extension rod

45‧‧‧Air holes

55‧‧‧Preformed body during demolding

56‧‧‧heated preforms

59‧‧‧Preformed body after 2-axis extension forming

60‧‧‧Extended blow molding machine

61‧‧‧heater

62‧‧‧Extended blow mould

64‧‧‧Extension rod

65‧‧‧Air holes

1(A) to (C) are three side views of a transparent bottle according to an embodiment.

Fig. 2 is a view for explaining an injection molding step in a method of manufacturing a transparent bottle according to an embodiment.

3(A) to (F) are views for explaining an extended blow molding step of producing a transparent bottle from the preform obtained in the injection molding step.

4(A) to 4(D) are views for explaining a method of manufacturing a transparent bottle according to an embodiment.

Fig. 5 is a graph for explaining the crystallization temperature and the crystallization melting temperature of the polypropylene resin by differential scanning calorimetry (DSC analysis).

6(A) to 6(C) are schematic diagrams showing temperature changes of the resin composition or the molded article thereof in the production step of the cold parison type injection stretch blow molding method.

7(A) to 7(C) are schematic diagrams showing temperature changes of the resin composition or the molded article thereof in the production step of the hot parison type injection stretch blow molding method.

Fig. 8 is a schematic view showing changes in temperature of a resin composition or a molded article thereof before and after demolding of an injection molding die in a cold parison type injection stretch blow molding method and a conventional hot parison type injection stretch blow molding method. .

Fig. 9 is a graph showing the relationship between the wall thickness of the main portion of the transparent bottle and the haze value.

Fig. 10 is a graph showing the relationship between the wall thickness of the main body portion of the transparent bottle and the buckling strength.

Claims (13)

A method for producing a container using a polypropylene resin composition as a resin material, and comprising: an injection molding step of introducing the melted polypropylene resin composition into a specific injection molding die to form a preform, which is released from the injection molding die after being cooled to 110 ° C or lower in the injection molding die; and an extension blow molding step of stretching and molding the preform Forming a container. The method for producing a container according to claim 1, wherein after the injection molding step, the step of quenching the preform from the injection molding die immediately after demolding to 60 ° C or lower is further included. The method of manufacturing a container according to claim 1, wherein after the above-described injection molding step, the step of cooling the preform to room temperature is further included. A method of producing a container according to claim 1, wherein in the injection molding step, the preform is cooled to 60 ° C or lower in the injection molding die, and then released from the injection molding die. The method for producing a container according to claim 1, wherein the polypropylene resin composition is produced from a vegetable material. The method of manufacturing a container according to claim 1, wherein in the injection molding step, the preform is cooled to 100 ° C or lower in the injection molding die, and then released from the injection molding die. The method of producing a container according to claim 1, wherein a haze value of the main body portion of the container formed in the injection molding step is 6% or less. The method of producing a container according to claim 1, wherein the body portion of the container formed in the injection molding step has a wall thickness of 0.7 mm or more. The method of producing a container according to claim 1, wherein the body portion of the container formed in the injection molding step has a buckling strength of 100 N or more. A method for producing a container using a polypropylene resin composition as a resin material, and comprising: an injection molding step of introducing the melted polypropylene resin composition into a specific injection molding die to form a preform, and in the injection molding die, the preform is cooled to a temperature not exceeding the crystallization temperature of the polypropylene resin composition, and then released from the injection molding die; and an extension blow molding step The preform is subjected to stretch blow molding to form a container. A container formed by using a polypropylene resin composition as a resin material, wherein a thickness of a main body portion is 0.7 mm or more, and a haze value of the main body portion is 6% or less. The container of claim 11, wherein the body portion has a buckling strength of 100 N or more. The container according to claim 11, wherein the polypropylene resin composition is produced from a vegetable material.