DE1604684B2 - Method and device for producing a hollow object from thermoplastic, crystallizable plastic - Google Patents

Description

The invention relates to a method for producing a hollow object made of thermoplastic, crystallizable plastic by extrusion of a

tubular preform and its stretching

,, .. for molecular orientation, whereby the: preform brought into a blow mold and by relative internal overpressure until it rests on its inner wall is inflated, and a device for performing this method.

In such a method, generally known, for example, from DT-Gbm 1 821 021, the preform is formed inflated in a molten or plastic state.

An extruded plastic pipe is also known from German Auslegeschrift 1 157 378 to cool for the production of hollow profiles. The related device has facilities for Extruding the material in the molten state through an annular nozzle, a forming sleeve attached to attached to the nozzle, means for quenching at least the surface of the preform that is exposed to the mold sleeve are connected, a cooling bath, which is directly connected to the mold sleeve for further Cooling of the preform is provided, means for conveying the preform, the can close around this, and means for expanding the preform against the inner wall a blow mold with the help of an internal fluid pressure.

With the known method, hollow objects made of thermoplastic material at high speed. The on this Well-made hollow objects, however, are cloudy and, moreover, do not have a very high height Firmness on.

It is therefore the object of the invention to provide a method for producing a very solid, almost crystal-clear, hollow object made of thermoplastic, crystallizable plastic.

According to the invention, this object is achieved in that, in the method mentioned at the beginning, the preform for crystallizing the material is cooled and ^{heated to a temperature within 8 °} C. below the crystalline melting point of this material immediately before stretching and inflation.

The hollow articles made by this process have a strength that makes them suitable for use makes them suitable as containers, and are almost as clear as glass containers.

A device of the type mentioned at the beginning is suitable for carrying out this method, in which, according to the invention a heating bath is provided between the cooling bath and the blow mold.

In the following, for example, preferred embodiments of the invention are given with reference to the drawings explained in more detail. It shows

F i g. 1 shows a section of the cooling and heating device of an embodiment of the device,

F i g. 2 schematically shows an embodiment of FIG Apparatus that can be used to manufacture containers, and

F i g. 3 shows a modified embodiment of the device.

Polymers such as B. polystyrene, polyvinyl chloride, nylon and various cellulose derivatives can be used in the process, preferably with the normally solid polymers of the mono-1-olefins worked that contain up to 8 carbon atoms, and especially with high polymers Degree of crystallization, e.g. B. those with high

specific gravity, such as ethylene polymers and isotactic polypropylenes, poly-4-methylpentene-1, Polybutene and the like.

Preferably, the method with the olefin is carried out, which have a degree of crystallization of at least 70% and preferably at least 80% at 25 ⁰ C. The homopolymers of ethylene and the copolymers of ethylene with higher mono-1-olefins, which have a specific gravity of about 0.940 to 0.990 g / cm ³ at 25 ° C., are particularly suitable.

The higher crystalline olefin polymers do not have a single solidification and melting point, but they have a crystal solidification point at which maximum crystal formation occurs when the molten polymer is cooled, and separately therefrom a crystal melting point at which crystallization disappears when a polymer sample is heated from a cooled crystal state. Usually the latter temperature is several degrees above the crystal freezing point. When polyethylene having a specific gravity of about 0.960 g / cm ^3, the crystal solidifying point at about 122 ⁰ C. is polyethylene having a specific gravity of about 0.960 g / cm ^3, the crystalline melting point is usually about 133 ° C.

The temperature at which these highly crystalline polymers are stretched is very important when making a maximum orientation and solidification of the polymer should be achieved. It is necessary, for example, that the Polymer has a practically crystalline state. If the temperature of the polymer is too low, the Elongation become uneven, and the thin wall of the structure formed is prone to cracking. It is therefore it is desirable that at least a part of the polymer wall is brought to a certain temperature so that they are in a crystalline state very close to that Melting point of the polymer crystallites is located. A device that is used to carry out this temperature adjustment can be used is shown in FIG. 1 shown. ,

In Fig. I, the cross-head mold 10 has a mold head 11 to which a mold sleeve is attached so that the extruded tube is guided directly into the mold sleeve. The mold sleeve has an elongated cylindrical section 12 against which the extruded tube is pressed by internal pressure. A jacket 13 completely surrounds the cylindrical section 12 and, between the jacket 13 and the section 12, encloses a number of annular chambers 14, 19, 21, 22. The chamber 14 is arranged towards the entrance of the mold sleeve and via a line 16 with a source connected for the cooling fluid. When extruding 1-olefin polymers, such as. B. ethylene polymers or polypropylene, in which one works at press temperatures in the range of about 177 to 204 ⁰ C, water at room temperature, ie about 21 ⁰ C, is suitable for this purpose. This cooling water flows through the line 16, through the chamber 14 and exits through a line 17. The cooling water circulates through the part of the mold sleeve located at the entrance of the mold sleeve and is at a sufficiently low temperature that at least the surface of the extruded tube is cooled so that the polymer in the vicinity of the outside of the tube attains a crystalline state. When the pipe is guided through this cooling section of the molded sleeve, a temperature gradient is created in the wall of the pipe. In order to keep the temperature of the tube more uniform, the tube is then passed through the exit part of the mold sleeve where the temperature is regulated by a heating fluid introduced through line 18, circulated through chamber 19 and through a conduit 20 exits. Hot pressurized water can be used for this purpose.

If, for example, polyethylene with a specific

ίο weight of about 0.960 g / cm ^{3 is to be} temperature conditioned, pressurized water with a temperature of about 113 to 116 ⁰ C can be used. The annular chambers 21 and 22, which are provided between the jacket 13 and the section 12 of the mold sleeve, are connected to means for generating a vacuum so that the space between the inner wall of the mold sleeve and the extruded tube can be evacuated. As in Fig. 1, the chamber 22 with the space between the ferrule and the tube is represented by a number of

Openings 23 connected. These vacuum connections, 'those on the part of the mold sleeve located towards the entrance and are located at their center, allow during extrusion and temperature .conditioning, to hold the pipe wall firmly against the inner surface of the molded sleeve, thereby reducing the heat transfer is improved. Other vacuum connections can be provided. An opening on the The output part of the molded sleeve is for the Commissioning useful.

The temperature-conditioned tube emerges from the cylindrical section 12 of the mold sleeve and runs between guide rollers 24. In many cases the desired stretching temperature is slightly higher than the temperature at which the polymer begins to soften. In these cases it is desirable, as in FIG. 3, can be changed by the The inner diameter of the wall section is enlarged at its part located towards the entrance. There one

40 'vacuum tapping is not provided at this point, the pipe does not come into contact with it . ' Part of the inner wall of the mold sleeve, and the final reheating is carried out by radiation, guided. This section with an enlarged diameter is denoted by the reference numeral 29 in FIG. 3. It was also found that the hot plastic passed over a sharp edge ;. can be, preferably made of an insulating. Material exists without sticking at temperatures, where sticking would normally occur on contact with a larger area. An annular plate 30 is therefore on the exit side the mold sleeve, as shown in FIG. 3 shown, provided. This annular plate 30 serves as a guide for the polymer tube as it leaves the mold sleeve. Instead of the hot, circulating liquid In the section 29 of the molded sleeve located towards the exit, electrical resistance heaters can be used be used.

The device described above is useful in the conditioning of comparable polymer pipes and [reversible during conditioning of preforms

be used in blow molding. In the course of the process, reheating of the extruded Tube are regulated so that the outer part of the tube is in the crystalline state and solidified by orientation, while the inside of the tube is relatively sticky and in one

5 6

fusible state is maintained so that when forming device 46, which a plurality of forms, the pipe is tightly enclosed by the mold sleeve, halves 47, which are attached to endless belts 48 and 49 a firm, tight connection with the part of the pipe. The belt 48 rests on pulleys 50 which are clamped together. A device 51, while the belt 49 on pulleys 52 and device, which is used to manufacture solidified containers 5 53. If these disks 50, 51, 52, 53 rotate, can be used, which are brought into one by blow molding the belts 48, 49 to form the mold halves 47, is shown in FIG. 2 shown. The thermo position, as represented by the mold halves 47 a plastic polymer, is made from a Kreuzkopfpreßf orm. When these mold halves 47 are brought together 31 extruded through an opening 32 in a mold sleeve 33, they close a part by clamping. In this arrangement, the mold sleeve 33 io of the extruded pipe, as between the two, does not have the task of reheating the pipe, as shown by mold halves 41b. If the closed in connection with the form sleeves of the F i g. 1 and 3 mold halves 47 move forward, the tube is described, but only serves to pierce by a needle 54, through the air in the extruded tube or at least its exterior to cool the enclosed portion of the preform so that the tube in a Cooling bath 34 15 is blown as it can be passed between the mold halves 47 c, where the entire polymer is shown. The tube thereby conforms to the tube in a uniformly crystalline state of the cavity of the blow mold as it is brought between the. The tube is then removed from the cooling mold halves 47 c / is shown. Since the blow molding bath 34 move out through endless belts 36 and 37 in the extrusion direction, the tube is pulled and placed in a heating bath 38. This section between the blow molds by a knife heating bath 38 can have a porous bronze sleeve 56 cut off. The mold halves 47 are. through which high-pressure steam is blown or through when the belts 48 and 49 run over the pulleys, which run a hot .Wärrne Transferrnedium pumped 51 or 53, and the shaped bottles are, or it can be a bath of a heating fluid, ejected from the blow mold and fall into a z. B. ethylene glycol. Becomes a bath of these 25 receptacles. In the operation of this type of apparatus, the ethylene glycol is kept under pressure, it is desirable to move the belts 48 and 49 so as to relieve any internal pressure that when the mold halves 47 come together, the same that is maintained in the tube in order to pull the preform so that it is inflated with this behind the heating bath 38. By moving one speed forward, the heating bath 38 raises the tube to a temperature within 30 which is slightly greater than the extrusion speed. half a few degrees, for example within about 8 ^° C. As a result, a longitudinal tension is exerted on the conditioned preform below the crystalline melting point of the polymer, and it is brought about. This is the preferred temperature for longitudinal molecular orientation in the parison in order to achieve maximum consolidation orientation prior to blow molding. Get started through this. 35 borrowed longitudinal extension, the tube is solidified so that

The tube can be further in a porous sleeve 39, it tears less easily or thin spots when blowing conditioned, which supports the pipe when it forms to. The gas pressure in the pipe at the time the blow mold 40 is passed. The blow mold 40 is where the blow molds are closed two mold halves that surround the heated tube, part of the tube that is enclosed by the blow mold, Can be brought together if it is sustained by the 40, so that by evacuating the porous sleeve 39 comes. One end of the tube becomes space between the blow mold and the preform by clamping with the aid of the bottom piece 41 of this part of the preform against the walls of the Blow mold 40 closed, through which the bottle bottom blow mold is pressed. Shaped by a suitable combination will. Heating elements 42 can in this part nation of these features can provide sufficient pressure The blow mold 40 can be placed around the portion of 45 continuous in the extruded parison To heat the tube, which can be maintained by disconnecting, so that only a slight is closed so that an effective, dense compression of pressure around the parison in the blow Conclusion is formed. The remainder of the blow mold 40 is used to achieve the desired inflation of the mold cooled by bringing about a coolant through windings of the preform.

43 circulates. After the blow mold 40 has around the tube 50 objects, such as e.g. B. Bottles that have closed after this is pressurized using a process of oriented polymers from 1-olefins. Gases produced by the cross-head mold 31, in particular polypropylene, will have pressed the tube against the walls of the blowing properties which pressed it into the mold 40 for numerous purposes and formed the bottle. Make an air technology usable. These properties ring or jacket 44 can be provided, which surrounds 55, among other things, a high orientation porous sleeve 39 in order to further stress the temperature conduction stress, high impact / tear resistance of the pipe before blow molding and a high modulus of elasticity,
support. Instead of using compressed air R- ¹ Ii
inside the tube can devices in Example I.
Blow mold 40 can be provided to pre-60 polyethylene with a specific gravity between the space. see tube and the walls of the blow mold 40 to 0.960 g / cm ³ at 25 ° C was continuously evacuated so that the conditioned tube pressed inside in the form of a preform of about 5 cm of the blow mold 40 is vacuum deformed. . Diameter and a thickness of about 1.19 mm

F i g. 3 shows an embodiment, the preferred This tube was directly in a form sleeve

wise for the continuous production of relatively smaller 65 out, as in F i g. 3 shown where it immediately byc!

Container is used. The extruded tube, water cooled with a temperatu

that circulates inside the sleeve, as described above, from about 21 ° C through the jacket of the sleeve)

suitable has been conditioned, runs directly to a The surface of the tube quickly became under dii

Bred softening temperature and then heated the tube again to about 121 ⁰ C in the heating section of the mold sleeve. As the tube emerges from the sleeve, it is stretched longitudinally and then trapped between mold halves which completely tightly enclose the tube and seal both ends of the tube which are in the blow mold. A bottle is then made by evacuating the space between the blow mold and the preform; so that the preform is pressed against the inner surface of the mold. The bottle produced in this way has a molecular orientation in its walls and is much stronger than a bottle which is produced directly from the hot, extruded preform without the temperature conditioning described.

Example 2

Blow molded bottles of approximately 296 cm ³ were made from homopolymer polypropylene and homopolymer linear polyethylene. The extruded preforms of each of the two plastics were blow molded to make both hot blown blow molded bottles from the preform which was in the hot melt state just after it came out of the extruder and oriented blow molded bottles from the preforms initially at ambient temperature cooled and then reheated to a temperature slightly below the melting point, whereupon they were blow molded into bottles.

The following table gives the main extrusion conditions and the equipment used to:

Table I.
Conditions for extrusion molding the preform

The main extrusion conditions and equipment used are summarized below. -, ..:.

A) General

Extrusion press: 38mm screw press (manufactured by Modem Plastik Machinery Corporation), Die: 90 ° cross head die, die opening: 10.6 τη τη diameter, Die end: 8.2mm diameter, screw: nylon type.

B) Preforms for oriented bottles

C) preforms for hot-blown bottles

Pipe temperature, front
Pipe temperature, rear
Die temperature ....
Connector and

Screw speed

Polypropylene

YlTQ

166 ° C

. 182 ° C

20 rpm

Polyethylene

YlTC
166 ⁰ C
215 ° C,

: 43% ,:

32 rpm

Pipe temperature, front
Pipe temperature, rear
Die temperature ...
Discharge speed

Head pressure

Internal pressure in the preform

Resulting average wall thickness of the preform

Screw speed

Cooling the preform

Molding process

Polypropylene

221 ° C

204 ⁰ C

199 ° C

41 cm / min

151 kg / cm ²

0.07 kg / cm ²

3.1 mm 44 rpm

Water spray internal pressure

Polyethylene

221 ° C

204 ⁰ C

199 ° C

48 cm / min

183 kg / cm ²

0.42 kg / cm ²

3.2 mm 44 rpm

Water spray internal pressure .. The following table gives the main conditions for bottle blow molding :; » · ■■■ '■' ■ -

Tables'^; \ '

Conditions and method ¹ for blow molding
of bottles

The main conditions for bottle blow molding are as follows:

A) hot-blown _bottles:; . . ■ .. · ■.

Preform condition: as extruded
Mold construction: mold, for 296 cm ³ bottle from the Standard Phillips Petroleum Company, using 15 cm cylinders. for the closing pressure.

1. Polypropylene bottles ·. '' ■ ...

a) Preform extruded in shape and stopped.

b) 85 l / h air supplied and closed at the front.

c) pause for 4 seconds, then apply a pressure of 2.1 kg / cm ² for a further 4 seconds.

d) Remove the bottle and repeat the procedure.

Note: shape kept at room temperature by water cooling.

2. Polyethylene bottles

a) Preform extruded in shape and stopped.

b) 283 l / h air supplied and closed at the front. : c) 1 second pause and then for more

A pressure of 14 kg / cm ^{a is} applied for 4 seconds.

d) Remove the bottle and repeat the procedure.

Note: shape kept at 13 ° C by tap water cooling. '■: ·

B) Oriented bottles

1. Temperature conditioning block for the preform

55

60 material: aluminum .;

Heating method: steam passed through hollowed-out block.

ID block: 2.2 cm.

Inner lining: Teflon.

2. Conditions for preheating and blow molding

Preform length: 7.6 cm.
Form: Standard 296-cm ³ shape of Phillips Petroleum Company.
Molding tension: 150%.

409 538/244

9 Polyethylene "- 'polypropylene 2.1 kg / cm ²
7 min Steam pressure on the block.
Preform condi-
tion time '' ... ·. ': ... ^: . 5.6 kg / cm ²
, 6 min

On bottles made according to the above conditions The following attempts were made. for Comparative evaluation carried out:. .

Experiments carried out

The experiments performed for this comparative test evaluation were the following:

A) Molding compound, pellets as received

1. Flow rate: ASTM D 1238-62 T.

23O ⁰ C "';■' .-.

a) 2160 g load. ... .

^{! :} b) 21,600 g load. . :. ·. ■

B) Bottles, test samples from the side wall

1. Specific gravity: ASTM D 792-60 T, process: method A, water immersion. ■ 2. Thickness of the side walls of the bottles used for,. the experiment were used. ^:

3. Shrinkback, maximum in both main directions.

, 4. Orientation relief tension; · Maximum in both main directions; ASTM D 1504-61; 5. Orientation relief temperature at. Maximum stress in both main directions; .5 ASTM. D1504-61. '■':.

. 6. Flip ultimate tensile ¹ in two main directions at 23 ⁰ C, 4 ^o C, und.-18 ° C; DeBeIl and Richardson Incorporated, parallel ^{strip 1} film material - attempt, short sample. . ..., .. ■>. ·

7. Modulus of elasticity when flexed in both main directions; ASTM D. 790-63, \; 8. Light transmission: ASTM D 1003-61, Method B (recording spectrophotometer using visible wavelengths at ... range of 400 to 700 millimicrons). :; ^;

C) Bottles shaped like ^: ' ^: ' ■ ■

1. Drop tear strength at 23 ° C for _: all: bottle types except for those made of oriented

. Polyethylene, if dropped on the floor, on its side and under. 45 ° against the ground. Also became a test carried out with a drop on the floor at 4 ° C for all types of bottle; ASTM D 20 Committee, proposed preliminary test method for measuring the FaIl-ZeD tear strength of blow molded containers. ..;. ■ ·

2. Water vapor transfer: 38 ° C ,. 9.0 % relative humidity, with a desiccant inside the bottle. ·. ■■■■■■::

; Table III

Summary of the flow velocity tests. ASTM D 1238, 23O ⁰ C, 4 g batch

material

Flow velocity in ^: '■ -
g / 10 min area Extruded diameter in
mm. . ■. . . .1 , 74 Area;· average 0.9 to 1.0
123 to 131- average , 30. 2.7 to 2.77 : 0.95
127 1.05 to 1.15
96 to 99 ■ 2 3.23 to 3.35 1.1
98 3

Polypropylene, Profax 6723

21 600 g load

Polyethylene, Marlex 6009
. 2160 g load .: .. '■:

21,600 g load . · ..,

Table IV Summary of test results on test samples from the side walls of the bottles

Hot blown area Oriented area Hot blown area Oriented area Measured properties Polypropylene Polyethylene Polyethylene Polypropylene By
cut 0.902 to 0.905 By
cut 0.906 to 0.908 By
cut 0.946 to 0.947 By
cut 0.954 to 0.957 Spec. Weight, 23 ° C (g / cm ³ ) 0.903 0.908 0.946 0.956 Wall thickness of the 0.28 to 0.48 0.18 to 0.46 0.20 to 0.33 0.15 to 0.20 used Bottles (well) ..... 0.36 0.28 0.25 0.18 Maximum return 1 to 15 27 to 45 34 to 42 40 to 53 shrinkage (%) 1 to 10 26 to 47 10 to 18 41 to 63 Circumferential direction ... 6.0 37 38 50 Axially 4.0 37 14th 54

11th

Table IV (continued) 12

Measured properties

Hot blown polypropylene

average

area

average

Oriented polypropylene

Area average

Hot blown
Polyethylene

area

average

Oriented polyethylene

area

Maximum orientation relief tension kg / cm ²

scope

Axially

Orientation relief temp. ( ⁰ C) at maximum stress

scope

Axially

Impact tear strength (mkg / cm ³ ) 23 ° C

scope

Axially

4 ° C range

Axially

-18 ° C range

Axially

Spec. Weight,

23 ⁰ C (g / cm ³ ) ......

Wall thickness of the

used

Bottles (mm)

Maximum shrinkback (%)

scope

Axially

Maximum orientation relief tension (kg / cm ² )

scope

Axial: ...

Orientation relief temp. ( ⁰ C) with maximum complaint

scope

Axially

Impact tear strength (mkg / cm ³ )

23 ⁰ C scope

Axially

"4 ° C range

Axially

-18 ° C range

Axially

Modulus of elasticity at bending 105 kg / cm ² )

23 ⁰ C scope

Axially

Light transmission,

visible

Area*) (%)
Violet, 400 m microns green, 500 m microns red, 700 m microns ..

0.55 0.18

163

173

1.35 1.18 1.26 0.92 0.14 0.12

0.903

0.36

6.0 4.0

0.55 0.18

163 173

1.4

1.2

1.28

0.96

0.15

0.12

0.157 0.186

0.53 to 0.56 0.098 to 0.25

162 to 173 to

1.09 to 1.85 0.92 to 1.43 1.09 to 1.60 0.50 to 1.18 0.10 to 0.25 0.04 to 0.27

0.902 to 0.905

0.28 to 0.48

1 to 1 to

5.2 to 5.6 0.10 to 0.25

162 to 173 to

1.14 to 1.9 0.96 to 1.5 1.14 to 1.6. 0.52 to 1.2 0.1 to 0.23 0.04 to 0.28

0.141 to 0.171 0.167 to 0.200

(0.256mm average thickness)

57.3 65.1 68.0

56.3 to 58.3 64.2 to 66.0 66.9 to 69.1

11.3 10.9

161 164

6.55 8.06 7.47 8.40 8.31 10.1

0.908

0.28

37 37

11.2 10.8

161 164

6.7 8.3 7.7 8.6 8.5 10.4

0.264 0.272

: 9.5 to 12.6 10.6 to 11.3

155 to

156 to

5.13 to 7.30 8.47 to 9.57 4.79 to 9.31 3.88 to 10.1 7.05 to 10.1 9.25 to 10.9

0.906 to 0.908

0.18 to 0.46

27 to 26 to

9.5 to 12.6 10.5 to 11.2

155 to

156 to

5.3 to 7.5 6.6 to 9.8 4.9 to 9.6 6.1 to 10.4 7.3 to 10.4 9.5 to 11.3

0.231 to 0.29 0.249 to 0.287

. (0.24mm average thickness)

82.3 86.6

87.5

82.0 to 82.6 86.2 to 87.0 86.9 to 88.1 0.13 0.07 to 0.18
no burden

140 to 142
No attempt

2.27
2.18
1.93
1.68
1.26
1.43

0.946

0.25

1.09 to 3.44
1.35 to 2.94
1.26 to 2.52
1.35 to 2.55
0.92 to 1.68
1.09 to 1.93

0.946 to 0.947

0.20 to 0.33

to 42
until 18

0.12 0.07 to 0.18
, no load

140 to 142
no attempt

2.3
2.2
2.0
1.7
1.3
1.5

0.100
0.186

0.96 to 3.6
1.4 to 3.1

1.3 to 2.6

1.4 to 2.4
0.96 to 1.7

1.1 to 2.0

0.082 to 0.118
0.162 to 0.206

(0.233 mm
average Thickness)

20.4
26.8

27.1

19.1 to 21.7

25.2 to 28.4
25.1 to 29.1

4.6

3.7-

136
139

4.45
3.78
3.36
2.77
5.21
4.79

0.956

0.18

50
54

4.6
3.6

136
139

4.5
3.9
3.4
2.8
5.3
4.9

0.202
0.184

4.5 to 4.6 3.4 to 4.6

132 to 140 137 to 140

2.10 to 5.45 3.53 to 4.88 1.85 to 4.79 1.43 to 4.11 3.78 to 7.48 3.53 to 6.30

0.954 to 0.957

0.15 to 0.20

44 to 53 41 to 63

4.5 to 4.6 3.4 to 4.6

132 to 140 137 to 140

2.2 to 5.6 3.6 to 5.0 1.0 to 4.9 .1.5 to 4.2 3.9 to 7.6 3.6 to .6.4

0.173 to 0.209 0.254 to 0.314

(0.231mm average thickness)

39.1
53.8
60.2

38.5 to 39.7 52.9 to 54.7 59.2 to 61.2

*) In comparison, microscope cover glass, 0.215 mm thick, gives the following permeability: 400 m microns - 92.3%, 550 m microns - 92.4%, 700 m microns - 91.6%.

13 14 ^

Table V ■ Summary of the test results from bottles

attempt Hot blown
Polypropylene Oriented '
Polypropylene Hot blown
Polyethylene ■ Oriented, ^.
Polyethylene Drop tear strength in cm, at
23 ⁰ C waterfall, fall on the
Bottom (10 bottles tested)
Maximum height for
"No damage"
Minimum amount for damage: .....
Type of damage
Fall on its side, 23 ⁰ C
(10 bottles tested)
Maximum height for ^:
"No damage"
Minimum amount for damage
Type of damage
23 ⁰ C, fall to the floor below
45 ° (10 bottles tested)
Maximum height for
"No damage"
: Minimum amount for damage ......
Type of damage
4 ° C, fall to the floor
(10 bottles tested)
Maximum height for
"No damage"....'...........
Minimum amount for damage
Type of damage
Water vapor permeability in g
0.025 mm / 24 h, at 38 ⁰ C, 90%
relative humidity and one
Desiccant in the bottle
average
Individual values 46
^31:;
(b), (c)
92
92
(b), (C)
61
61.
(b), (c)
15 ■
9
(b)
: 0.208
0.207, 0.204, 370
370
(a)
370
210
(a)
340
..240
(a)
370
370
^(a)
0.141
: 0,135,0,160 ,. 61
- ■■■ · ■ ··· 46
(C)
152:
152. ■: ■
. (b), (c) :. v.
215
. ' 152:
(b), (c)
61:.
46
(b), (C)
0.127
0,126,0,136, not examined
370 -
370 ■
(C) - ,,.
0.121
0.127, 0.114, 0.213 0.128 0.120

(a) Torn at the pinch-off point on the bottom.

(b) Torn circumferentially around the floor.

(c) Torn lengthways from the ground up.

■ The following results are obtained from the tests:

1. The treatability of the two compounds used in this assessment is essentially - borrowed the same. The two points lie at the shear rate and the apparent viscosity for each connection on the same curve as those used for Hi-Fax 1400 (melt index - 0.8 g / 10 min) in B e r η h a r d t's "Processing of Thermoplastic Materials". at These compounds should cope with the higher shear rates under normal process conditions show equivalent treatability. Both types of material were oriented in bottles at temperatures just below the corresponding melting points, for maximum orientation to obtain. This orientation was measured by the degree of shrinkback and the Orientation relief tension to establish the fact that a significant orientation is present in the oriented bottles. Orientation in the hot-blown Bottles is negligible as no noticeable

A significant relief stress was obtained, although even a relatively high degree of shrinkback was measured in samples of the hot blown polyethylene bottles. This particular shrinkback directs the normal hot melt memory on regression properties this linear polyethylene, a phenomenon that occurs when polypropylene is hot melted does not occur. This fact is supported by the extruded diameters in the flow velocity tests, which show that polyethylene has a significantly larger diameter (3.3 mm versus 2.7 mm for polypropylene).

3. The impact absorption capacity of polypropylene is very effectively improved by orientation, proven by the blow-tear and the bottle drop tests. Unexpectedly there is a greater improvement in this respect with polypropylene than with polyethylene.

4. The orientation in polypropylene also creates a toughness that allows it at temperatures can be used under normal temperature,

where ordinary unoriented polypropylene cannot be used. Particularly the phenomenon of orientation in polypropylene resulted in a plastic which in certain physical and mechanical properties are essentially different, so that Open up many possible uses for it that are not possible with normal polypropylene are. . ; ..

5. The clarity of the two materials is improved by orientation, but the polypropylene was improved by the orientation to such an extent that its light transmission in the visible spectrum almost reached that of glass.

6. The resistance to water vapor transmission of the oriented polypropylene bottles is considerably better than that of the hot-blown bottles.

20th

The above data were obtained under the following experimental conditions. ASTM test procedures were used where possible. In addition to these, exact comparative tests were carried out using technically valid procedures, so that results were obtained which allow a comparison between the test sample and bottles tested. Unless otherwise specified, all tests were carried out in an environment of 23 ^° C. and 50% relative humidity, with preconditioning of at least 24 hours in the same environment immediately before the test.

A. Flow rate

35

Procedures according to ASTM D 1238 are carried out using a temperature of 230 ° C, a 4 g batch and corresponding loads of 216O..and 21600 g for the two Try. Duplicate tests were carried out in each case. The compounds were examined as obtained in pellet form. The one described in the ASTM number above Standard equipment was used with loading weights to apply the load.

B. Specific weight

Method A according to ASTM D 792-60T was used. Distilled was used as the immersion medium Water was used, and the test sample consisted of the middle bulk one Bottle, about 6 cm long, and using the entire circumference. A small Weight was attached to the test sample so that it sank below the surface of the water, and a small percentage of a wetting agent was added to reduce surface tension to belittle. Five tests were performed on each type of bottle, in each case five different bottles were used.

C. Thickness

All bottles used for this evaluation were checked for profile thickness at three longitudinal points of the Bottles examined. Five measurements were taken at each point in the circumferential direction in the center, 6 mm from the bottom and 6 mm from the top of the side wall. It was a Staridard micrometer '· used with a Ball socket that touched the concave surface.

D. Shrinkback

All test bottles were examined for shrinkback properties using individual test plugs cut from each major direction of the bottle. The De BeIl and Richardson Shrink Back Tester was used with white mineral oil as the immersion medium. These test samples were exposed to temperatures above their respective melting points in total immersion for 10 seconds. In polyethylene, this temperature was 149 ° C and the case of polypropylene 171 ° C. The temperature tolerance during the immersion was ± 1 ° C. Through testing ^and: error experiments it was determined that 10 seconds is an appropriate time for "a maximum return shrinkage in each case, The test samples were 6 mm wide and 50 mm long. The shrinkback was expressed as the percentage change in length that occurred during this high temperature immersion. Mineral oil normally attacks polyethylene and polypropylene, but the time was too short for such an attack to take effect and possibly affect the "shrinkage properties. At least one sample from each major direction of each bottle evaluated was examined. ·

E. Maximum orientation relief tension

This property was measured using the essential ASTM methods D 1504-61. The Instron test device and a test sample consisting of a strip with parallel edges, 6 mm wide, was clamped between the drawing jaws,

: whereupon this experimental arrangement from a cylindrical heater was enclosed, the

. was set so that it generated a heating rate of 10 ° C per minute. the of the. Experimental set load applied was automatically recorded, and the maximum load was taken out of this curve to calculate the maximum orientation stress.

The heating rate was controlled manually by changing the power consumption of the cylindrical heater was adjusted so that it followed a standard heating curve, wherein this was superimposed on the recorder by a thermocouple with low Inertia has been actuated and the thermocouple is within 3 mm of the Center of the test sample was arranged, but this did not touch. In every main direction two values were determined for each type of bottle. ·: '

F. Orientation relief temperature at maximum load or maximum stress

This property was described during the above Determined experiment to determine the orientation relief stress. The temperature at maximum voltage was determined by taking the temperature from the curve recorded on the temperature recorder

409 538/244

at the moment of the maximum exposure the ■ - .: test sample was taken. '■■; ■ ··

G. Impact Tensile Strength. -

: This property was found in both main

Measurements of all bottle types at temperatures. ·, of 23 ⁰ C, 4 ° C and -18 ° C. · The an-:., ■. The applied test method was the De-BeIl and Richardson parallel stripes - impact - tensile test: using the short sample. 10 measurements were made for each bottle type in each main. - .., -; _: direction carried out. A Baldwin shock meter: was used, with liquid CO ₂ injected to obtain test temperatures below normal temperature; The test sample and the jig holding it were complete. permanently enclosed in the detachable environmental chamber and both for a period of. : .3 minutes before the impact, kept at the test: ·· ■ - 'temperature. Before the start of all the test series, the clamping device for the test specimen was cooled to approximately the test temperature ... · ..._. :. ;. :

:: The! Temperature control was carried out, manually: by connecting the inlet of the CO ₂ 'coolant; ■ ·. · Has been adjusted accordingly to set the temperature. within ± 1 ° C of the desired temperature. The test. ·. · Samples were 5 cm long and 6 mm wide. They were carefully made by trimming with a new, sharp razor blade and then examining the edges of the cut under magnification to make sure the edges were not damaged. All experiments were carried out with the 0.55 mkg hammer.

pH. Modulus of elasticity for bending

f.. The ASTM D790-63 procedures were

■ - carried out. The test samples would be 6 mm wide and 25 mm long and with a razor blade out of the bottle in both main directions -

; cut. The span was approximately 12.5 cm using a one-point load, being the tip radius and the radius of the supports were 1.5 mm. For this work it was Instron gauge used on a load

! ■. range from 0 to 0.1 kg. The crosshead speed (Loading speed) was 0.5 mm per minute, and it was assumed that the Deflection of the test sample essentially

; . is identical to the crosshead movement required for the calculations was used. Five measurements were made in each major direction for each Bottle type carried out.

I. Light transmission

The. Light transmission was determined at each bottle type using test samples with approximately the same thickness, with ¹ being the samples were cut directly from the bottle walls. A Bausch and Lomb recording spectrophotometer (Spectronic 505) was used for the experiments, using the visible light range of 400 to 700 mm microns. The light transmittance was expressed as a percentage of light transmitted through the test sample light by use of a reference beam, the X 100% throughput •• \: iässigkeit showed. In order to support the comparative assessment of the test samples, a comparison device made of microscope cover glass was used, the thickness of which is approximately that of the test. ^; search samples corresponded (0.215 mm). The tests were carried out under the conditions of the environment, with double measurements being carried out on individual test samples. The test specimens were examined as they were cut out of the bottles without being brought into a plane or flat shape. Thus, the natural curvature of the bottle wall was present in these light transmission tests. The values taken out for comparison were those obtained at wavelengths at 400, 550 and 700 m microns, that is, violet, green and red.

J. Bottle drop tests

Bottle-drop tensile strength was determined according to the essential procedures proposed by an ASTM D 20 standards committee, entitled "Test Method for Measuring Drop-Impact Resistance of Blow-Molded Containers". This procedure recommends three types of falls, one on the floor; one on its side and one at a 45 ° angle to the floor. Ten bottles of each type, except those made from oriented polyethylene, were tested for tearing in each recommended manner at 23 ° C with the bottles filled with water at the test temperature. Since only a limited number of bottles made of oriented polyethylene were available, these were excluded from this series of tests; '-.' .. ■ "
^: The. Experimental apparatus for regulating the · Auf .-. treffwinkeis and the height consisted of a horizontal trap door arrangement, which could be arranged at any height up to about 3.6 m and which had a holder that held the bottle in the exact fall position, and. which was also provided with a release mechanism by which the trap door could be folded down and away from the test bottle in such a way that the bottle could fall freely and without rotation so that it opened in exactly the same position as it was before, when it was placed on the horizontal trapdoor. The same tests were carried out at 4 ° C, examining all types of bottles, but examining only the case on the bottom.
In each of these tests, 10 test samples were tested for all bottle types in order to obtain the minimum tear height range for each. This rupture height range was determined by determining the maximum height at which no tearing occurred and the minimum height at which tearing occurred. The range formed by these two values is essentially considered to be the minimum tear height range of the bottles. The type of damage was recorded in each case. Each bottle was tightly sealed with a screw cap after it was completely filled with tap water at the test temperature.

K. Water vapor permeability of the bottles

The water vapor transmission rate was measured by taking the whole bottle of an environment of 38 ° C and 90% relative humidity, 150 g of a desiccant (calcium sulfate) placed in the bottle and weight intake over time was examined. Three bottles of each type were so evaluated using weighing methods recommended by ASTM E 96 are, with at least three consecutive daily measurements that make up showed essentially a straight curve of the moisture uptake over time. the

The thickness of the bottles was determined after the test by cutting and measuring with a micrometer and this thickness was included in the calculations for water vapor transmission included, the latter in the

unit

g x 0.025 mm

' 24 hours

is expressed. This inclusion of the thickness in the calculation allows a direct numerical comparison between the bottle types. The bottles were effective sealed under a screw cap, using a resilient rubber seal.

For this purpose 2 sheets of drawings

Claims (1)

Patent claims: 1. A method of making a hollow article from thermoplastic, crystallizable Plastic by extruding a tubular preform and stretching it into a molecular Orientation, whereby the preform is brought into a blow mold and by relative internal overpressure is inflated until it is in contact with the inner wall, characterized in that that the preform is cooled to crystallize the material and immediately before Stretching and inflating to a temperature within 8 ° C below the crystalline melting point this material is heated. 2. Apparatus for performing the method according to claim 1 with means for Extruding the material in the molten state. State through an annular nozzle, a molded sleeve, which is attached to the nozzle, means for quenching at least the surface of the Preforms, which are connected to the mold sleeve, a cooling bath, which is directly connected is provided on the mold sleeve for further cooling of the preform, devices for Conveying the preform which can close around it and means for expanding it of the preform against the inner wall of a blow mold with the help of an internal fluid pressure, characterized in that between the cooling bath (34) and the blow mold (40) a heating bath (38) is provided. .3. Device according to claim 2, characterized in that. that the elongated form sleeve has a cylindrical section (12), one the form sleeve surrounding jacket (13), a number of spaced apart chambers (14,19, 21, 22) formed by the jacket (13) and the walls of the cylindrical section (12) and that at least one opening through the cylindrical section (12) (23), which connects the interior of the mold sleeve and one of the annular chambers (21, 22), a first line which connects the chimney (21, 22) with the openings (23) and a ■ Creation of evacuation facility, second lines (16), an annular chamber (14) and a Connect cooling fluid source and third lines (18) are provided, which the annular chamber (19) located towards the outlet of the mold sleeve and connect a source of heating fluid. 4. Apparatus according to claim 3, characterized in that. the inner diameter of the Mold sleeve in its section (29) in the vicinity of the chamber connected to the heating fluid source (19) is enlarged, and that an annular plate (30) with a relatively sharp inner edge, against which the preform rests, is attached to the output side of the mold sleeve.