CN1153102A - Process for injection stretch blow molding - Google Patents
Process for injection stretch blow molding Download PDFInfo
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- CN1153102A CN1153102A CN 96122777 CN96122777A CN1153102A CN 1153102 A CN1153102 A CN 1153102A CN 96122777 CN96122777 CN 96122777 CN 96122777 A CN96122777 A CN 96122777A CN 1153102 A CN1153102 A CN 1153102A
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- parison
- injection
- temperature
- mould
- stretch blow
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Abstract
An improved method for injection stretch blowing is provided. In the process, a molten resin is injected into an injection cavity defined by an injection mold, a lip mold and an injection core to form a desired preform, the cooling time for this preform being positively reduced to form a rigid skin layer on the outer surface of the preform without increasing the thickness. It is then released from the injection mold and transferred into the blow mold with a mouth portion being held with the lip mold while the skin layer keeps the configuration of the preform and the interior is in a high temperature state, and is stretch blow molded into a hollow molded article, at the moment when the surface temperature of the preform that rises due to its own interior temperature is significantly higher than a glass transition temperature (Tg) and is expected to reach to a peak temperature. Through strenching and blowing, it becomes completed hollow piece, e.g. bottles, most parts of which are ultrathin.
Description
The present invention relates to a kind of preformed parison that injection moulding is formed by synthetic resin that carries out continuously, stretch blow-molded then is a kind of forming method of hollow molding goods, and the major part of these goods for example bottle partly is ultra-thin.
As a kind of forming method that is referred to as to annotate stretch blow (injection drawing blow) moulding, this method comprises with a die lip mould delivers to blow molding die with it then immediately at its oral area clamping one injection moulding parison, carries out stretch blow-molded.
The 3 station type forming methods of in open 4-214322 of Japan Patent or the open 454997A1 of European patent, narrating, comprise that injection one molten resin to injection die cavity forms desirable parison, with the die lip die clamp holding oral area with this parison from injection mould from mould, this moment, this parison was in such state, can keep profile on the parison surface owing to cooling off the cortex that forms fast, and be in the condition of high temperature, wherein inner cooling is not finished as yet, with the die lip mould it is sent to blow molding die from the injection mould tale quale, own inner heat raises and reaches in the time durations before the peak temperature owing to it in the surface temperature of parison then, with its stretch blow-molded be a thin-gage goods.
This forming method is significantly effectively for the such moulded products of stretch blow-molded for example bottle (it comprises that average thickness is the bottle part of 0.2-0.35mm), but thinks and can give rise to trouble with the stretch blow-molded ultra-thin moulded products of higher draw ratio (0.15mm or thinner bottle part are arranged).
Need high draw ratio with the stretch blow-molded moulded products of thick and short parison.Yet under PET or analog situation, when parison thickness is big, need the regular hour to come the parison of chilled injection molding, and parison continue crystallization and causes and turn white by injection molding.Under cold mould base technical situation, for the stretch blow-molded parison that will be cooled to room temperature heats again, or use temperature control technology, before stretch blow-molded, in order to control its temperature, the high temperature parison further to be heated, this crystallization can not cause trouble especially, because carried out heat treatment in the past immediately at stretch-blow, and caused this thickness to be defined as up to 4.0mm.Yet standing immediately in the stretch blow-molded method with the parison of high temperature from mould, because the very big influence of crystallization, this thickness is limited to 3.0mm.Therefore be difficult to improve draw ratio for thick and short parison.
In addition, carry out in the stretch blow-molded method at high temperature immediately from the parison of mould, forming temperature is lower than the forming temperature that uses in cold mould base technology or the temperature control technology forming method, because stretch blow-molded is that heat is brought up under the situation that is higher than its glass transition temperature (tg) and carried out in the parison surface temperature is own by it, and just when parison was stretched blow molding, the temperature of parison was because the surface area as a result of drawn expanded increases and decline rapidly.Therefore, when draw ratio was such, when promptly the final stage temperature of drawn expanded was significantly less than glass transition temperature, thickness deviation or crazing were tending towards causing bad shape of formation.
This forming temperature can be 95 ℃ or higher, is being 70 ℃ or higher rapidly behind mould by minimizing control surface temperature cool time.However peak temperature does not still reach 100 ℃.Interior heat 100 ℃ or more low temperature be not enough, and be not enough to parison be stretched and expand 13 times or more.
In stretch blow-molded, it is believed that according to the thickness of injection moulding parison and temperature for example most of thickness of bottle can be lowered by improving draw ratio.The reduction of this thickness is very useful for saving material and reducing waste material, and its influence economically with society on all very big.The reduction of thickness greatly reduces axial bending intensity, and therefore limits the use as single bottle, yet can be used as a kind of packing container development of novelty when combining with paper container or analog.On the other hand, accept immediately in the stretch blow-molded forming method,, be difficult to improve stretching formation recently and have the ultra-thin bottle of major part owing to the restriction of uniting of above-mentioned parison thickness and forming temperature at injection molding parison.
Therefore, an object of the present invention is to provide a kind of notes stretch blow novel molding method, this method allows to produce hollow molding goods so ultra-thin so that can fold, and even accepting immediately the stretch blow-molded method from the parison of mould from mould with high temperature, also increase the thickness of parison unlike conventional method.
Have been found that at moulding material be under the PET situation, the hollow molding goods for example folding thickness of be easy to craft of bottle are 0.15mm or littler, and when the surface temperature of parison in stretch blow-molded be 105 ℃ or when higher, for PET, even with high temperature from mould under the situation of the parison that mould and thickness are limited, can the above-mentioned ultra-thin bottle of moulding.Yet demonstrate not is all will be at 105 ℃ or higher high-temperature area yet, and only under given conditions can moulding yet.
" ultra-thin " expression wall thickness is 0.15mm or littler than the bottle wall thickness (approximately 0.25-0.35mm) partly of commercial commercially available PET bottle in the present invention.
Therefore, an object of the present invention is to provide a kind of notes stretch blow forming method, this method may further comprise the steps: molten resin is expelled in the injection die cavity that is limited by injection mould, die lip mould and injection cores forms desirable parison; By positively reducing the cool time of parison, form [and do not improve its thickness at the outer surface of parison; From mould, meanwhile this cortex keeps the profile of parison and inside is in the condition of high temperature to the parison that will have a notch portion (being held by the die lip die clamp) from injection mould; Send it to blow molding die; In the surface temperature of parison since its own in heat raise and reach this moment of peak temperature apparently higher than glass transition temperature (Tg) and expectation, with its stretch blow-molded be the hollow molding goods, the major part of these goods is ultra-thin.
Specifically, stretch blow-molded is to be higher than at least 20 ℃ of its glass transition temperatures owing to heat in himself is increased to or more that carries out constantly in the surface temperature of parison.
In addition, the present invention's direct gas with desirable pressure after molten resin is injected the injection die cavity fully is pressed into the interface between molten state parison and the injection cores, with its air pressure with the inner surface of parison and the surface isolation of injection cores, thereby the surface that parison is pressed to injection mould is positively cooled off fast the outer surface of parison.
In addition, the present invention is exactly in the about 70 ℃ temperature range of parison surface temperature behind mould, the parison that PET is formed carries out from injection mould from mould, when expection reaches peak temperature, with this parison stretch blow-molded be the hollow molding goods, its major part is ultra-thin, thickness is 0.07-0.15mm, meanwhile, the surface temperature of parison reaches 105 ℃ or higher high temperature range owing to the interior heat of himself raises.
Fig. 1 is with PET injection molding parison, high temperature from mould behind mould, hull-skin temperature is schemed over time; And
Fig. 2 is the view that is used to narrate parison and stretch blow-molded bottle.
At first, the temperature of mould is set, its upper temp is minimum, and its underpart temperature is lower than the intermediate portion The temperature of dividing. Closure is in injection mould and the die lip mould of such control and stationary state. And with temperature The injection cores that degree arranges slightly highlyer than injection mould is inserted injection mould from die lip mould top, forms an injection Die cavity.
After the close die, with the PETG of molten condition at the bottom of annotate mouth and run through mould Section injects and is cooled to 13-17 ℃ above-mentioned injection mold cavities, is formed with the type of back cover drum Base, it wants the thickness average out to 2.5-3.0mm (except neck and the bottom) of stretched portion, The height of stretched portion is about 90mm. After injection filling mould is finished, immediately from the top of injection cores Or the sidepiece of neck applies about 8kg/cm2Compressed air, beginning pressurize or be in pressure maintaining period In.
For the parison in the injection mould, after the beginning pressurize, because the relation of thickness, immediate precedence is cold Thin oral area and bottom. With the surfaces externally and internally of injection mould surface and injection cores Surface Contact owing to cold But begun to form cortex. Mid portion still is in high temperature attitude and melting or semi-molten state. So this type Base integral body is in soft condition not yet can stand external pressure. Like this, air enters parison along injection cores Between the interface, push away said parison to the next door.
As a result, be cooled and the inner surface of the parison neck that solidifies and bottom from the surface of injection cores (from This place produces and separates) separate. In addition, parison is because the air pressure that is pressed between injection cores and parison And be compressed against the surface of injection molding. The air of boundary exists until stop its confession as separating layer Till answering. This so that the inner surface of parison separate with the surface of injection cores, and the outer surface of parison with The surperficial close contact of injection mould, this is opposite with typical injection moulding. Therefore, the cooling of outer surface Carry out energetically, although depend on thickness cool time, generally in the cool time in 3 seconds, form Desirable cortex.
Because positive cooling and the cortex hardening that forms at the parison outer surface. Along with continuous cooling skin Layer extends to the inside of parison, has increased thickness and has reduced interior heat. In this, work as outer surface Cortex reach stop air feed when keeping the Parison Shape state and with parison from mould from mould. Stop cold Carry out from mould from mould in the time of but. In addition, the ejecting prior to injection cores from mould from mould. Then The above-mentioned die lip mould of the eck part by being used for forming parison ejects parison from injection molding.
Although the parison that forms owing to quick hardening by cooling, immediately the surface temperature behind the mould equal or Be lower than glass transition temperature (about 70 ℃), but because its internal temperature height, so surface temperature Still raise in a short time, as shown in Figure 1. Reaching before the peak temperature, holding with the die lip die clamp Neck is sent to blow molding die with this parison. Use the stretching bar at axial tension parison, and reach in expection In the moment of the peak temperature on parison surface (190 ℃), carry out air blowing stretching and expand 14 Doubly or more.
This drawn expanded is carried out under such state, and namely the inside of high temperature is by inside and outside cortex Encapsulation is at the no molecular orientation of this stage expection. Being accompanied by the drawn expanded surface area increases and the thickness quilt Attenuate, therefore because as the drawn expanded process of in the past discussion in, parison is cooled off rapidly, type The temperature of base becomes near glass transition temperature. As a result, the drawn expanded of final step is near glass The glass transformetion range is carried out, even the temperature when therefore moulding begins is 105 ℃ or highlyer is Molecularly oriented completely. Even from low temperature to high temperature, have small for PET in addition The temperature difference all stretch. Do not cause even therefore stretch and expand in high drawn expanded multiplying power yet Thickness deviation. Therefore parison 1 is formed the firm and ultra-thin bottle of the about 0.13mm thickness of tool Son 2, as shown in Figure 2.
The bottle 2 of moulding like this, the thickness of bottom approaches, although it is thin not resemble the bottle part, therefore can easily becomes flat (except the bottleneck portion), and can easily revert to original state when air blowing in it.In addition, it easily can be folded or rolls, therefore it can be converted into the stampings transportation.
[embodiment]
Moulding material: PET
(production number 9921W can buy from Easstm an Kodak Company)
The parison size
The height (mm):
Bottleneck portion 10.8
Stretched portion 88.0
2. the cross section external diameter (mm) of Zhan Pinging:
Bottleneck portion 19.0
Stretched portion 18.9
3. thickness (mm)
Bottleneck portion 1.0
Stretched portion 2.5
4. the thickness range (mm) of the part that is stretched:
(2.6 bottleneck portion side) to 1.8 (bottle bottom side) product size 1. volumes: 1028cc2. shape: rectangle bottle 3. height (mm): bottleneck portion 16.0
The cross section external diameter (mm) that bottle part 251.54. flattens:
Bottleneck portion 19.0
Bottle part 70 (turning) is thickness (mm) 5.:
Bottleneck portion 1.0
Bottle part 0.136. draw ratio (axially): 2.86 times of area ratios: 19.2 times of parison formation condition barrel zone temperatures (on average): 280 ℃ of forming temperatures (measured value): 17.5 ℃ of injection filling times of 16.8 ℃ of core rods of die cavity: 3.3 seconds from mould air pressure: 8kg/cm
2Cool time (after the pressurize): the parison temperature of 2.4 seconds stretch blow-molded conditions when mould; 68 ℃ of peak temperatures: 109 ℃ of time to peaks (behind mould): the parison temperature during 5 seconds stretch-blows: 109 ℃ from from the time of mould to blow molding: 5 seconds blowing air pressure (kg/cm
2): initial pressure 5,
Secondary pressure 26, blow molding die temperature: normal temperature.
Claims (3)
1. a process for injection stretch blow molding may further comprise the steps: molten resin is injected the injection mold cavities that is limited by injection mould, die lip mould and injection cores form desirable parison; By the cool time of certain minimizing parison, form a [at the outer surface of parison and do not increase the thickness of said cortex; With the eck part that the die lip die clamp is being held parison, make parison from injection molding and injection cores from mould, meanwhile the cortex of parison keeps the profile of parison, and the inside of parison is in high temperature; It is transferred to blow molding die; That that is much higher than owing to himself interior heat raises that glass transition temperature (Tg) and expection reach peak temperature in the parison surface temperature constantly, with its stretch blow-molded be the hollow molding goods, the major part of these goods is ultra-thin.
2. one kind as the desired process for injection stretch blow molding of claim 1, after it is characterized in that molten resin injects injection mold cavities, the gas of desired pressure is pressed into the parison of molten condition and the interface between the injection cores, the inner surface of parison is separated with core surface; And facing to the surface pressure parison of injection molding, the outer surface of cooling parison fast really.
3. one kind as claim 1 or 2 desired process for injection stretch blow molding, it is characterized in that formed PET parison carrying out in such temperature from injection molding from mould, be parison immediately the surface temperature behind mould be about 70 ℃, that that is in owing to himself interior heat raises that 105 ℃ or higher high temperature range and expection reach peak temperature in the parison surface temperature constantly, the major part of these goods is ultra-thin, with its stretch blow-molded be the hollow molding goods, thickness is 0.07-0.5mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 96122777 CN1153102A (en) | 1995-09-29 | 1996-09-27 | Process for injection stretch blow molding |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP276774/95 | 1995-09-29 | ||
| CN 96122777 CN1153102A (en) | 1995-09-29 | 1996-09-27 | Process for injection stretch blow molding |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1153102A true CN1153102A (en) | 1997-07-02 |
Family
ID=5127439
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 96122777 Pending CN1153102A (en) | 1995-09-29 | 1996-09-27 | Process for injection stretch blow molding |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1153102A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100355631C (en) * | 2003-04-15 | 2007-12-19 | 雀巢水业管理技术公司 | Thin-walled container for products |
| CN103619562A (en) * | 2011-05-24 | 2014-03-05 | 艾博特心血管系统公司 | Method and system for manufacturing polymer endoprosthesis by injection molding and blow molding |
| CN109352954A (en) * | 2018-11-08 | 2019-02-19 | 广州紫江包装有限公司 | A kind of the pipe embryo forming method and pipe embryo mould of plastic bottle |
-
1996
- 1996-09-27 CN CN 96122777 patent/CN1153102A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100355631C (en) * | 2003-04-15 | 2007-12-19 | 雀巢水业管理技术公司 | Thin-walled container for products |
| CN103619562A (en) * | 2011-05-24 | 2014-03-05 | 艾博特心血管系统公司 | Method and system for manufacturing polymer endoprosthesis by injection molding and blow molding |
| CN103619562B (en) * | 2011-05-24 | 2016-08-31 | 艾博特心血管系统公司 | The method of prosthese in formation polymer |
| CN109352954A (en) * | 2018-11-08 | 2019-02-19 | 广州紫江包装有限公司 | A kind of the pipe embryo forming method and pipe embryo mould of plastic bottle |
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Legal Events
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|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C01 | Deemed withdrawal of patent application (patent law 1993) | ||
| WD01 | Invention patent application deemed withdrawn after publication |