KR100436217B1 - Manufacturing method of polypropylene bottle for sterilize - Google Patents

Abstract

The present invention relates to a method for manufacturing a sterile polypropylene container, which can minimize deformation during high temperature sterilization while using polypropylene in the manufacture of a plastic container, so that it is possible to replace a PET container of heat and pressure resistance conventionally used for sterilization. It is an object of the present invention to provide a method for producing a sterilized polypropylene container, and in order to achieve the above object, the present invention is to cool the polypropylene injection molded product obtained by setting the temperature of the injection cylinder at 200-220 ° C for 4 seconds. After obtaining the base material, the base material was placed on the mold and heated for 6 seconds by varying the temperature of the upper and lower subdivisions, and the upper side and the middle side were heated to 140 ± 5 ° C. and the lower side to 130 ± 5 ° C., followed by 6 seconds After primary blow molding by pre-blowing at an air pressure of 3 to 4 kg / cm 3 over, the primary molded product was blown twice for 8 seconds at an air pressure of 14 to 16 kg / cm 3 at 60 ° C. Poly Sterilization characterized in that is can be achieved by providing a method for producing a propylene container.

Description

Manufacturing method of polypropylene bottle for sterilize

The present invention relates to a method for manufacturing a sterile polypropylene container, and more particularly, to replace the PET container of heat and pressure resistance used for conventional sterilization and at the same time to minimize the deformation during high temperature sterilization poly A method for producing a propylene container.

In general, a plastic container can be molded into two methods, a direct blow molding ("DBM") method and a stretch blow molding ("SBM") method. A representative product manufactured by the milk container is, and a representative product manufactured by the SBM method is a beverage container.

The DBM method has a disadvantage in that the transparency of the produced product is inferior and heavy, but in the case of the SBM method, there is an advantage in that the product is excellent in transparency due to high stretching and the weight of the product is relatively low, resulting in relatively low unit cost. The molding method of plastic container is gradually moving from DBM method to SBM method.

The general method of molding the plastic container by the SBM method is a process of injecting and melting raw materials, injecting the molten raw materials, a pre-blow process of forming the first injection molded product, the final molding of the first molded product Blowing process and taking out the final molded product. Plastic containers, which are the final molded product thus manufactured, are used through a separate sterilization process as necessary.

In this case, when manufacturing the plastic container by the SBM method, the container is manufactured using ordinary PET as a raw material, because PET is suitable for plastic container products requiring high transparency.

PET is generally used because of its low heat and pressure resistance, so it cannot be used for products that require high temperature sterilization, so it is limited to products that do not require high temperature sterilization such as bottled water. Plastic containers are also manufactured using PET having heat and pressure resistance characteristics that can be applied to products.

However, recently, a problem has been raised that environmental hormones are generated in plastic containers made of PET as a raw material, which is known to be due to acetaldehyde generated during the processing of PET.

In addition, PET has a disadvantage in that it needs to be sufficiently dried and then injected at a high temperature due to the nature of the material, and also undergoes a pre-blow blow or blow process using high pressure air after injection. As a result, the production cost of the product is increased to increase the price of the product.

In particular, even in a plastic container manufactured using heat and pressure resistant PET, there is a problem of causing deformation without maintaining the original shape in the sterilization process at a high temperature due to the plastic properties.

Due to the problems of PET described above, a plastic container is manufactured using polypropylene instead of PET, and when polypropylene is used, there is an advantage that the container can be used with confidence because environmental hormone is not generated. It is expanding.

In addition, since polypropylene is a thermoplastic resin, the recycling degree is very high, the specific gravity is low, and the price is low, and thus the production cost can be lowered. As a result, it is possible to economically perform a pre-blow or blow process.

However, polypropylene has a disadvantage of causing severe deformation when the sterilization process at high temperature due to the absence of heat and pressure resistance characteristics, and thus has a disadvantage that its application range is limited despite the excellent properties of polypropylene.

Therefore, the present invention is to solve the above-mentioned problems, it is possible to minimize the deformation during high temperature sterilization while using polypropylene in the manufacture of plastic containers can replace the heat- and pressure-resistant PET containers used for conventional sterilization It is an object of the present invention to provide a method for producing a sterilized polypropylene container.

The present invention to achieve the above object

In the method of manufacturing a sterile polypropylene container for melting and injecting polypropylene to obtain a preform, and then pre-blowing the base material to be molded first, and then blow the primary molded product to obtain a plastic container ,

After cooling the polypropylene injection molding product obtained by setting the temperature of the injection cylinder at 200-220 ° C. for 4 seconds to obtain a base material, the base material was placed in a mold and heated at different temperatures in the upper and lower parts for 6 seconds, The intermediate side was heated to 140 ± 5 ° C. and the lower side to 130 ± 5 ° C., followed by pre-blowing at an air pressure of 3 to 4 kg / cm 3 for 6 seconds, and the primary molded product was molded at 60 ° C. 14 It can be achieved by providing a method for producing a sterilized polypropylene container, which is blown twice over 8 seconds at an air pressure of ˜16 kg / cm 3.

The polypropylene container manufactured through such a method causes deformation of about 1% to 2% even through high temperature and high pressure sterilization process, so that it is possible to use a PET container of heat and pressure resistance used for conventional sterilization.

As can be seen from the above method, the present invention enables the production of a container in which deformation can be minimized at high temperature sterilization by varying various conditions in the process of manufacturing an existing polypropylene container, and the method is more specifically described below. Explained as follows.

According to the present invention, in order to provide a container which can minimize deformation during high temperature sterilization while using polypropylene, first, a polypropylene resin is added to a melter, melted, and then injected to obtain a polypropylene injection molding, and cooled to obtain a base material. .

Melting and injection of polypropylene for obtaining a base material can be carried out by applying a conventional method. In the present invention, a polypropylene injection product was obtained at a temperature of an injection cylinder of 200 to 220 ° C.

When the thus obtained polypropylene injection product is cooled, a base metal can be obtained. Since polypropylene has good crystallinity, crystallization proceeds relatively quickly. At this time, when the crystallization of the polypropylene is too fast, it is important to prevent the crystallization from progressing too fast because the container is broken during the pre-blowing process and the blowing process. In this invention, the obtained polypropylene injection molded product was cooled at 8 degreeC for 4 second, and the base material was obtained.

The obtained base material is primarily molded through a pre-blowing process, and in order to obtain the base material, a process of cooling the polypropylene injection molding is performed. In this process, a temperature difference between the inside and the outside of the base material occurs, thus preventing pre-blowing. do. That is, due to the temperature difference between the inner side and the outer side of the base material, the drawing of the base material does not proceed evenly during the pre-blowing process, resulting in a problem of product defects.

Therefore, in order to uniformize the inside and outside temperature of the base material so that the pre-blowing can be easily performed, the base material is placed on the mold just before the pre-blowing, and the base material is heated.

According to the present invention, the base metal is placed in a mold and heated at different temperatures of the upper and lower parts for 6 seconds, but the upper and middle sides are heated to 140 ± 5 ° C. and the lower side is 130 ± 5 ° C., followed by preblowing.

In this way, heating the base material by changing the temperature of the upper and lower subdivisions in order to improve the flow of the base material so that the pre-blowing and blowing can proceed easily, and it is important to heat at a temperature higher than the VICAT softening point of the polypropylene resin. It is important to heat above 130 ℃ because it can prevent deformation of the molded product. The temperature of the lower side should be lower than the temperature of the upper and middle to make a uniform product while preventing the raw materials from pushing towards the bottom. The difference is 10 ℃, and as a result, the upper and middle sides are 140 ± 5 ℃ and the lower side. It is important to heat this to 130 ± 5 ° C.

The base material is placed in a mold and heated for 6 seconds, followed by a preliminary blowing process. In the present invention, the pre-blowing is carried out at an air pressure of 3 to 4 kg / cm 3 for 6 seconds, so the transverse stretching ratio is about 38%. The primary molded product of about degree was obtained.

The primary molded product through the pre-blowing as described above is subjected to a blowing process for the final molding, in the present invention is carried out twice blown for 8 seconds at an air pressure of 14 ~ 16kg / ㎠ at 60 ℃ by the longitudinal draw ratio A polypropylene container having 54.5% and a lateral stretch ratio of 250% was obtained.

The propylene container can be used to replace the heat- and pressure-resistant PET container used for conventional sterilization by causing deformation of about 1 to 2% even after high temperature autoclaving at 121 ° C. for about 30 minutes.

At this time, it is very important to maintain a constant temperature of the mold in the pre-blowing or blowing process described above, in the present invention, in order to control the temperature of the mold, oil having a higher accuracy than water is used as a medium.

Polypropylene containers which can be manufactured by the above method include a chemical container, a detergent container, a cosmetic container, a juice container, a beverage container, and the like, and are easily regenerated by using polypropylene and are very environmentally friendly because no environmental hormones are detected. It is a phosphorus product.

In addition, the polypropylene container according to the present invention has the advantage of excellent transparency and excellent impact strength and surface smoothness in terms of the properties of the material, inexpensive compared to the conventional PET container, and low in specific gravity of the resin The weight can be reduced by about 34%, which is very economical.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are only presented to aid the understanding of the present invention, but the present invention is not limited thereto.

<Examples 1 to 4>

After cooling the polypropylene injection molded product obtained by setting the temperature of the injection cylinder at 220 ° C. for 4 seconds to obtain a base material, the base material was placed on a mold and the temperature of the upper and lower subdivisions for 6 seconds was set to the temperature shown in Table 1 below. And pre-blown with air pressure of 4 kg / cm &lt; 3 &gt; over 6 seconds, followed by primary molding, and the primary molded product is blown twice for 8 seconds with air pressure of 15 kg / cm &lt; 3 &gt; Got courage.

Comparative Example 1

After cooling the polypropylene injection molded product obtained by setting the temperature of the injection cylinder at 215 ° C. for 6 seconds to obtain a base material, the base material was placed on a mold and the temperature of the upper and lower parts for 6 seconds was set to the temperature shown in Table 1 below. After heating, primary molding was performed by pre-blowing with an air pressure of 4 kg / cm &lt; 3 &gt; over 2 seconds, and the primary molded product was blown twice for 5 seconds with an air pressure of 15 kg / cm &lt; 3 &gt; to obtain a plastic chemical container.

Experimental Example

The polypropylene containers obtained in Examples 1 to 4 and Comparative Example 1 were preheated at room temperature for 15 minutes and then sterilized for 28 minutes at a pressure of 1.8 bar at 121 ° C., and then cooled, before and after sterilization. The length of was measured and the measurement is shown in Table 1 below.

division Upper temperature (℃) Middle side temperature (℃) Lower temperature (℃) Inner diameter (mm) Outer diameter (mm) Tokyo (mm) Overall length (mm) Example 1 Before sterilization 140 140 130 30.40 35.80 87.20 221.00 After sterilization 30.25 35.52 85.53 217.87 Example 2 Before sterilization 138 135 130 30.40 35.80 87.20 221.00 After sterilization 29.78 35.32 85.33 217.64 Example 3 Before sterilization 135 135 125 30.40 35.80 87.20 221.00 After sterilization 29.84 35.31 85.21 217.38 Example 4 Before sterilization 130 130 120 30.40 35.80 87.20 221.00 After sterilization 29.78 35.43 85.25 217.52 Comparative Example 1 Before sterilization 90 110 110 30.40 35.80 87.20 221.00 After sterilization 28.81 35.12 85.24 226.31

As shown in Table 1, in Examples 1 to 4, the polypropylene container was manufactured under the preferred conditions of the present invention. It can be seen that the amount of change in the inner diameter, outer diameter, diameter and total length before and after sterilization at high temperature and high pressure is very small.

However, in the case of Comparative Example 1 in which the polypropylene container was manufactured under the conventional conditions, it can be confirmed that the amount of change in inner diameter, outer diameter, diameter and electron before sterilization and sterilization at high temperature and high pressure was very large compared with Examples 1 to 4.

Therefore, in the present invention, it is possible to manufacture a polypropylene container capable of minimizing deformation during high temperature sterilization by changing the conditions while using polypropylene in the manufacture of a plastic container, thereby sufficiently replacing the heat-resistant and pressure-resistant PET containers conventionally used for sterilization. Can be used.

As described above, the present invention can minimize deformation during high temperature sterilization while using polypropylene in the manufacture of a plastic container, so that a polypropylene container for sterilization can be replaced with a PET container of heat and pressure resistance used for conventional sterilization. It is a useful invention to provide a method for preparing.

Claims (1)

In the method of manufacturing a sterile polypropylene container for melting and injecting a polypropylene to obtain a preform, and then pre-blown the base material to be molded first, and then blow the primary molded product to obtain a plastic container, After cooling the polypropylene injection molding product obtained by setting the temperature of the injection cylinder at 200-220 ° C. for 4 seconds to obtain a base material, the base material was placed in a mold and heated at different temperatures in the upper and lower parts for 6 seconds. The intermediate side was heated to 140 ± 5 ° C. and the lower side to 130 ± 5 ° C., followed by preliminary molding by pre-blowing at an air pressure of 3 to 4 kg / cm 3 over 6 seconds, and then the primary molded product at 60 ° C. A method for producing a sterilized polypropylene container, which is blown twice in 8 seconds at an air pressure of 14 to 16 kg / cm 3.