KR20060076627A - Plastic for reheat blowing with improved infrared heat-up times - Google Patents

Abstract

The present invention relates to a plastic for reheating molding having improved infrared heating rate, and more particularly, to a plastic for reheating molding except polyester, wherein the primary particle size of primary particles is 0.1 to 500 nm. It relates to a plastic for reheat molding in which the infrared heating rate including carbon black of 0.1 to 20.0 ppm relative to the weight of the plastic is improved.

According to the present invention, the primary molded article is infrared ray by adding a certain amount of carbon black during polymerization or extrusion / injection molding of plastics requiring reheating, including polypropylene (PP) for bottles. It is possible to improve the productivity of the final product by improving the rate of temperature rise by the heater.

Plastic, Polypropylene, Carbon Black, Infrared, Heating Rate, Reheat, Forming

Description

Plastic for reheat blowing with improved infrared heat-up times}

1 is a graph showing the changes in the pre-heating Col-L and preform reheating temperature according to the carbon black content according to Examples 1 to 4 and Comparative Example 1 of the present invention.

The present invention relates to a plastic for reheat forming with improved infrared heating rate. More specifically, infrared polymerization can improve the productivity of the final product by increasing the rate at which the primary molded product is heated by the infrared heater by adding a certain amount of carbon black during polymerization or extrusion / injection molding of the plastic for reheating molding. The present invention relates to a plastic for reheat molding with improved speed.

Re-heating plastics are applied to applications requiring a process of heating with an IR heater after extrusion / injection molding in plastics for forming films, sheets, etc., including bottles. The use encompasses extrusion and injection molded articles (including preforms, also called parisons), and stretch blow molded articles (bottles are representative examples) made of the plastics in question.                         

Currently, the amount of plastic used as a bottle material as a substitute for heavy and fragile glass bottles is increasing at a rapid rate every year. Its main uses are blister packaging and sheets for packaging containers such as carbonated beverages, bottled water, fruit juices, tools, and the like.

Many plastic bottles are molded in an injection-blowing process. Polyethylene terephthalate (hereinafter referred to as 'PET'), which is the most representative of the plastics, has gone through two processes of injection-blowing in one machine but in the past two-stage method of producing injection and blow separately as the demand grows rapidly. The trend is to change to (2-Stage system). In the two-step method, the PET resin is melted and then injected into an injection mold to make a preform. In the blow process, the preform is heated using an infrared heater to a glass transition temperature (abbreviated as Tg) or more and then heated. Into a blow mold to apply a high pressure into a bottle. Other materials including PP other than PET also undergo the same injection and blow process when the two-stage method is applied.

On the other hand, when making a bottle from the preform, when the preform is black, it is known that the temperature increase rate is increased, so that the productivity tends to be high. In this regard, studies have been actively conducted to improve the temperature increase rate during reheat molding for polyesters including PET, but other methods have not been proposed for other plastic materials that are currently capable of two-step molding.

 Accordingly, in the present invention, as a result of extensive research to solve the above-mentioned problems of the prior art, it was found that the use of a specific carbon black can compensate for the disadvantages of other reheating plastics having a slower heating rate of the preform than polyester. The present invention has been completed based on this.

Accordingly, an object of the present invention is to improve the infrared heating temperature increase rate of the primary molded product by adding a certain amount of specific carbon black during polymerization or extrusion / injection molding of plastics requiring reheat molding except polyester, thereby improving the final plastic product. An object of the present invention is to provide a plastic for reheating molding having an improved infrared heating speed, which can improve productivity.

In order to achieve the above object, the plastic for reheat molding having improved infrared heating rate is:

Group consisting of polyethylene (PE), polypropylene (PP), polyethersulfone (PES), polycarbonate (PC), polymethylmethacrylate (PMMA), polyacrylonitrile (PAN) and polyvinyl chloride (PVC) In the polymerization or extrusion / injection molding of the re-heating plastic selected from the carbon black having a primary particle size (primary particle size) of 0.1 to 500nm characterized in that it is added to 0.1 to 20.0ppm relative to the weight of the plastic .

Here, the plastic is in the form of a preform or sheet.

The plastic can also be reheat molded to be used as a molded article, such as a sheet or a bottle.

Hereinafter, the present invention will be described in more detail.

As described above, in the present invention, by incorporating a specific carbon black during polymerization or extrusion / injection molding of the plastic for reheating molding, the temperature increase rate of the primary molded product by the infrared heater can be improved, thereby improving productivity of the final product. Provided is a plastic for reheat forming with improved infrared heating rate.

In general, the most commonly used plastic for reheat molding is polyester such as PET used in the manufacture of bottles, etc., but the present invention aims to improve physical properties of other plastics except for such polyester. In other words, plastics other than polyester, including PET or polyethylene naphthalate (PEN), are intended for all plastics that go through the steps of injection / extrusion molding-IR heating-final product.

Preferably, the plastics for reheating molding used in the present invention include polyolefin-based polyethylene (PE) and polypropylene (PP), and in particular, polyether sulfone (PES), polycarbonate (PC), polymethyl methacrylate. (PMMA, also known as acrylic), polyacrylonitrile (PAN), polyvinyl chloride (PVC), and the like.

Most preferably, PP or PC is used.

According to the present invention, the productivity of the final molded product manufactured by improving the temperature increase rate of the preform by adding a small amount of carbon black as a material absorbing IR when polymerizing the reheat-forming plastic or the extrusion / injection molding as described above. To increase.

Carbon black, which is a key additive used to improve the infrared heating rate in the present invention, has an average particle diameter of 0.1 to 500 nm. When the average particle diameter of the primary particles of the carbon black is less than 0.1 nm, it is very difficult to disperse it in a solvent or plastic in practice, and when it exceeds 500 nm, it is possible to increase haze and damage the appearance and properties of the product. This is high.

At this time, the amount of the carbon black is preferably 0.1ppm or more relative to the weight of the final polymer, that is, plastic, in order to see a significant effect, preferably 0.1 to 20.0ppm, more preferably 0.5 to 20.0ppm, the most good range Is 1.0-10.0 ppm. When the amount of the carbon black is less than 0.1 ppm, the increase in visible light absorption of the injection and extruded products is not sufficient, and when the amount of the carbon black exceeds about 20.0 ppm, the colors of the polymer and the molded article are biased to be too black.

The carbon black may be added at any stage of the polymerization process of plastics, and in some cases, a small amount of a master batch containing a large amount of carbon black may be added during primary molding of the plastic. However, it is preferable to add just before reheating molding in order to obtain the maximum improved characteristics of the rate of temperature rise by the infrared heater. In particular, in the case of PP or PC, it is preferable to add the powdered polymer recovered in the granular form after the polymerization process is completed.

According to the present invention, the amount of carbon black actually put into the reheating plastic and the productivity increase of the plastic product can be easily estimated and evaluated by measuring the Col-L of the product, thereby making it possible to use the current operating method of a commercial production process. It can be used to provide a plastic for reheat molding in which the infrared heating rate is improved.

On the other hand, the plastic for reheating molding having an improved infrared heating rate as described above is used for molding bottles, films, sheets, and the like, and is used for applications requiring a process of heating with an infrared heater after extrusion and injection molding.

That is, the plastic for reheat molding is prepared by injecting a specific amount of the specific carbon black as described above in the polymerization or extrusion / injection molding thereof to make a primary molded article such as a preform or a sheet containing carbon black, and then heated in infrared light. By the process of manufacturing the final molded product.

Typical processes include stretch-blow molding to make bottles from preforms, thermocrystallization to crystallize the screw necks of the preforms when making heat-resistant bottles, and thermoforming processes to make blister packaging products from sheets. Etc. can be mentioned.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

The Minolta CR-410 colorimeter was used for the color measurement of the granular polymer in the Example, and the Nippon Denshoku COH-300A haze meter was used for the color measurement of the molded article. Here, Col-L means larger white and smaller is black. The detailed definition of Col-L is based on the American Standard Test Method (ASTM).

Comparative Example 1

Using a PP material for injection molding, a preform for 1.5 liter bottles having a weight of 46 g and a body thickness of 4 mm was injected into a Nissei ASB-150 2 cavity injection machine.

Col-L of the preform was 91.0. The preform was heated in a Krupp LB-01E infrared blower to find the temperature of the preform at 140 ° C.

The following is the infrared heating condition of the bottle.

Infrared heating condition; Calories 95%, heating time 120 seconds, equilibrium time 10 seconds

Meanwhile, the reheating temperature and Col-L of the preform are shown in FIG. 1, respectively.

Example 1

Carbon black was added to the injection-molded PP material, followed by mixing in a twin screw extruder by adding 0.5% by weight of Raven 1170 (average primary particle diameter: 21 nm) of the Columbia Chemicals Company. The mixture from the extruder was cut into granules of 2.3 × 1.7 × 2.6 mm. This granular mixture is evenly mixed with the original injection PP material by dry blending to 1 ppm on a carbon black basis.

Preforms were injected in accordance with the method described in Comparative Example 1 using a Nissei ASB-150 2 cavity injection machine using an injection-molded PP material mixed with carbon black.

The preform Col-L was 88.5. The temperature of the preform was 144 degreeC when this was heated in the infrared blower on the conditions of the comparative example 1.

Meanwhile, the reheating temperature and Col-L of the preform are shown in FIG. 1, respectively.

Example 2

The preform was injected through the same procedure as in Example 1 except for blending the granulated mixture ground to 5 ppm on a carbon black basis.

Col-L of the preform was 83.2. As a result of heating this in the infrared blower on the conditions of the comparative example 1, the temperature of the preform was 160 degreeC.

Meanwhile, the reheating temperature and Col-L of the preform are shown in FIG. 1, respectively.

Example 3

The preform was injected through the same procedure as in Example 1 except for blending the granulated mixture ground to 10 ppm on a carbon black basis.

The preform Col-L was 70.7. This was heated in an infrared blower under the conditions of Comparative Example 1, the temperature of the preform was 178 ℃.

Meanwhile, the reheating temperature and Col-L of the preform are shown in FIG. 1, respectively.

Example 4

The preform was injected through the same procedure as in Example 1 except that the pulverized granular mixture was blended to 15.0 ppm on a carbon black basis.

The Preform's Col-L is 57.6, which is quite black in appearance. The temperature of the preform was 199 degreeC when this was heated in the infrared blower on the conditions of the comparative example 1.

Meanwhile, the reheating temperature and Col-L of the preform are shown in FIG. 1, respectively.

As described above, according to the present invention, primary molded products such as preforms and sheets may be formed by adding a specific amount of specific carbon black during polymerization or extrusion / injection molding of plastics that require reheat molding other than polyester. It is possible to improve the productivity of the final polyester product by increasing the rate of temperature rise by the infrared heater.

It is apparent that modifications and improvements are possible by those skilled in the art within the spirit or scope of the present invention. Accordingly, the simple modifications and variations of the present invention are all within the scope of the present invention, and the specific scope of protection of the present invention will be clarified by the appended claims and their equivalents.

Claims (4)

Group consisting of polyethylene (PE), polypropylene (PP), polyethersulfone (PES), polycarbonate (PC), polymethylmethacrylate (PMMA), polyacrylonitrile (PAN) and polyvinyl chloride (PVC) Characterized in that the carbon black having a mean particle size of 0.1 to 500 nm of primary particles is added at a concentration of 0.1 to 20.0 ppm relative to the weight of the plastic during polymerization or extrusion / injection molding of the plastic for reheat molding selected from Plastic for reheat molding with improved infrared heating rate. The plastic of claim 1, wherein the plastic is in the form of a preform or a sheet. A molded product formed by reheat molding a plastic according to claim 1. 4. The molded article of claim 3, wherein said molded article is a sheet or a bottle.

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