CA1168819A

CA1168819A - Method of producing shaped bodies from polylaurinlactam, as well as the shaped bodies obtained in accordance therewith

Info

Publication number: CA1168819A
Application number: CA000397249A
Authority: CA
Inventors: Werner Hartmann
Original assignee: Harwe AG
Current assignee: Harwe AG
Priority date: 1981-04-08
Filing date: 1982-02-26
Publication date: 1984-06-12
Also published as: NL8200595A; GB2096047A; ES509971A0; DE3114217A1; SU1111687A3; IT8202905A0; BR8201581A; ES8306642A1; AU8072582A; ZA821677B; FR2503719A1; SE8202121L; AU547362B2; DD202038A5; FR2503719B1; IT1158361B; DK150482A; GB2096047B; CS233725B2; ATA122382A

Abstract

ABSTRACT OF THE DISCLOSURE

Polylaurinlactam which is obtained by melting laurin-lactam, intermixing the melt with a catalyst and subsequent mixing of the mixture with an activator with polymerisation and which is east into threads or strands is in accordance with the invention comminuted into granulated material or chips and is injection moulded at temperatures from 220 to 255°C at pressure from 50 to 100 kp/cm2. The shaped body obtained in accordance therewith has superior physical proprieties.

Description

~ ~3~ 3 The present invention relates to a metho~ of pro-ducing shaped bodies from polylaurinlactam as well as the shaped bodies obtained in accordance therewith.
Uni-ted States Paten-t No. 3,793,255 discloses a method of producing shaped bodies by -the activa-ted anion:i.c poly-merisation of la.urinlactam in which two lactam melts are mixed separately with a ca-talyst and an activator under nitro-gen respectively and are passed to a mixing arrangement through separate pipelines maintained at the same temperature as the melts, and subsequently flow into a mould. The melts, on their way to the mixing arrangement, flow th.rough respectively a spiral tube system in siphon-like manner. By this process a polymer with properties which differ completely from convention-al polycaprolactam are obtained. The disadvantage of this method is however, tha-t serviceable polymerised cast products can lndeed be initially obtained, but the properties thereof ~ deteriorate very severely after a short space of time.
; German Offenlegungsschrift No. 2,507,549 discloses ` a method of p~oducing shaped bodies from polylactams, more especially polylaurinlactam, in which the monomeric lactam is melted, the melt is initially intermixed with a catalyst, the mixture obtained is mixed with an activator and the polymerised ; product is cast immediately afterwards into molds.
A modification of this method is described in German Offenlegungsschrift No. 2,559,749, according to which polylaurinlactam shaped bodies are produced by the method in which together with stirring, a polymerisation catalyst is added, at a temperature above 160C and below 170C, to a , ~ .
partial lactam melt in a separate boiler and the mixture is stirred. An activator is then added, with stirrin~, at a temperature which lies a few C lower than that of the first melt but which likewise lies in the range from below 170 C to above 160C, to an equivalen-t par-tial lactam melt whlch is in a separate boiler, and is stirred. The melts obtained are, with maintenance of their temperatures, in each case drawn off by a gear pump from their xespective boilers and axe passed through gently inclined pipelines, which have a volume which is greater by at least 1/3rd than that which corresponds to the delivery capacity of the pump, to the mixing zone, where they are mixed at a temperature from 170 C to 175 C and are injection moulded or cast through a spraying head without pressure or at low pressure. The polylaurinlactam products obtained in accordance with German Offenlegungsschrifts Nos.

2,507,549 and 2,559,749 have the following physical character-istics:
'; (a) a yield stress ~, measured in accordance with DIN 53,455, '~ from approximately 470 to about 520 kp/cm2;
' (b) an elongation, measured in accordance with DIN 53,455, :' upon yield stress ES from approximately 17 to approximately '' 25 percent;
(c) a -tear strength 6R, measured in accordance with ISO R 527, ' 20 from approximately 500 to approximately 630 kp/cm2;
~' (d) a tear elongation ~R~ measured in accordance with ISO R
527, from approximately 200 to 350 percent;
(e) a modulus of elasticity E, measured in accordance with DIN 53,457 Para 2.3, from approximately 19,000 to approxi-mately 22,000 kp/cm2;
(f) a limiting bending stress ~B' measured in accordance with ISO R 178, from approximately 750 to approximately 1,000 kp/cm ;
(g) a notched bar impact strength aK, measured in accordance with DIN 53,453, from approximately 55 to 65 kpcm/cm ;
(h) a ball thrust hardness 10", measured in accordance with ; DIN 53,456 stage C, from approximately 1,000 to approxi-.~ - 2 -`` 3 ~

mately 1,050 kp/cm ;
(i) an abrasion resistance, measured by means of Taber-Abrazer, from approximately 158 to approxima-tely 129 mm3/Upm;
(j) a creep rate stress ~1/1,000 (23C/95 percent), measured in accordance with DIN 53,444, from approximately 50 to approximately 60 kp/cm ; and (k) a creep modulus EC/1,000 (~20.0), rneasured in accordance with DIN 53,44~, from approximately 13,000 to approximately . 1~,000 kp/cm2.
Furthermore, German Offenlegungsschrift No. 2,602, 312 discloses a thread casting installation in which the aforesaid polylaurinlactam melts above can be cast into threads.
The present invention provides a method which is simple and which is smoothly feasible and which yields poly-laurinlactam shaped bodies having improved physical properties.
It has now been surprisingly found that, when the polylaurinlactam material of the above-mentioned Offenlegungs-schrifts and which does not melt upon the heating, but decom-poses in air at a temperature in the range from approximately 20 217 to 271 C and is no longer regenerable is distributed into a granulated materlal and this granulate-shaped material is shaped in the injection moulding process into shaped bodies, products having improved properties are obtained.
The present invention thus provides a method of producing shaped bodies from polylaurinlactam in which laurin-i~ lactam is melted, the melt is initially intermixed with a catalyst and then the mi~ture is mixed with an activator and is polymerised, the polymerising material is cast into threads or strands of a polymer which does not melt upon the heating, but decomposes at temperatures in the range from approximately 217 to 271C in air and is no longer regenerable, the threads or strands are comminuted into granulated material or chips

- 3 -:

and the comminu-ted ma-terial is injection moulded at temperatures from 220 to 255C at pressures from 50 to 100 kp/cm2.
The present invention also provides the polylaurin-lactam shaped bodies obtained by the method of the present in-vention. The polylaurinlactam shaped bodies of the invention have the following physical properties:
(a) a yield stress ~S' measured in accordance with DIN 53,455, from approximately 480 to approximately 500 kp/cm2;
(b) an elongation, measured in accordance with DIN 53,445, upon yield stress S from approximately 28 to 36 percent;
(c) a tearing strength ~R~ measured in accordance with ISO R
.~ 527, from approximately 550 to approximately 670 kg/cm ;
(d) A tearing elongation ER me sured in accordance with ISO R
~ 527, from approximately 220 to approximately 330 percent;
~ (e) a modulus of elasticity E, measured in accordance with DIN 53,457 Para 2.3, from approxima-tely 20,000 to approxi-mately 24,000 kp/cm2;
(f) a limiting bending stress 6B, measured in accordance with ISO R 178, from approximately 730 to approximately 920 kp/cm2;
(g) a notched bar impact strength aK, measured in accordance with DIN 53,453, from approximately 70 to approximately 85 kpcm/cm2; and . (h) a ball thrust hardness from (of?) 10", measured in accord-ance with DIN 53,456 stage C, from approximately 1,030 : to 1,060 kp/cm .
The polylaurinlactam obtained in accordance with German Offenlegungsschrift No. 2,507,54g or German Offenlegungs-`. schrift No. 2,559,749 may be used as starting material for effecting the method in accordance with the invention.
To produce the starting material, initially laurin-lactam is melted and the catalyst is mixed into this melt. After

- 4 -;

33~3 :, -thorough intermixing, the ac-tivator is added to the mixture.
The addi-tion oE -the catalyst -to -the laurinlactam melt, the subsequent admix-ture of the activator and the polymerisa-tion are preferably effected at a constant temperature, advantageous-ly in the range from 150 to 200C, in which respect a tempera-.~`; ture of 160C has proved to be optimum.
One may also in accordance with German Offenlegungs-schrift No. 2,559,749 proceed in such a way that equivalent ~. . quantities of laurinlactam are introduced into two separate boilers and are melted with s-tirring. Whilst maintaining a temperature below 170C and above 160 C, a catalyst is intro-. duced into one boiler and stirred. Subsequent to this an : activator is added with stirring to a separate boiler, which ; has an equivalent quantity of lactam melt, at a temperature which lies a few C below that of the first melt, but also within the range from below 170 C to above 160 C. The contents of two containers are then drawn off, with maintenance of their temperatures, in each case through a gear pump out of their boilers and passed from the two gear pumps through pipelines : 20 with a maximum inclination to the horizontal of 10 to a mixing zone, the pipelines have a volume which is greater by at least one-third than the delivery capacity of the pump. The material ~ is briefly intermixed in the mixing zone.
.. ~ In accordance with the invention, the polymerising material is cast immediately into threads or strands. For example the thread casting apparatus disclosed in German Patent No. 2,602,312 can be used for this operation. The threads or strands are then comminuted into a granulated material or into chips. For example the threads or strands can initially be processed by ro:Lling into bands which are then cut into strips and finally comminuted into granulated material. Conventional mills or granulating machines can be used for comminuting the

- 5 , polymer. The ~ranulated materials can have any desired, uniform or non-uniform shapes~ For example, the granulated material used may have a rectangular, more especially square cross-section. Preferably the granulated material used has an average particle diameter of 2 to 5 mm. A cubic granulated ma-terial having edge lengths of 3 mm proved to be particularly Eavour-able.
The polylaurinlactam granulated material intermediate product is then injection moulded. In this respect, -tempera-10 tures from 220 to 255C as well as pressures from 50 to 100 kp/cm are used. The moulding operation can be effected in conventional injection moulding machines having heated extruder worms and nozzles. Preferably the rear region of the worm is - heated to a temperature of 240 C, whilst the front re~ion of ~-~ the worm is heated to a temperature of 250 C. The nozzle heating lies preferably at a temperature of 250 C.
The production of the polylaurinlactam shaped body '~
in accordance with the invention can be effected, for example, in the following manner.
In accordance with the method described in German Offenlegungsschrift No. 2,507,549 or German Offenlegungsschrift No. 2,559,749, from laurinlactam there is produced a polymerisa-tion product which is supplied in the polymerising state, advan-tageously at temperatures from 160 to 168 C, to a thread cast-ing installation. Advantageously the polymerising material is conducted by a pump into a thread casting installation includ-ing a discharge traverse for the continuous casting of threads or strands. The polymerisation product then emerges as a liquid, thread-shaped material from the thread casting installa-tion and passes over a half-open guide channel, for example as an approximately round-profiled liquid plastics thread, to a set of mixing rollers, the roll gap of which is continuously vari-.~

able and is rolled to the desired thickness and wid-th. The band passing ou-t oE the roll gap by way of a guide channel is then cut upon passage through cutter rollers into parallel strips, which are then comminuted by a subsequently-arranged cutter head of a cutter roller into granulated material or chips. For example, the granulated materials have, by virute - of a square cross-section of the strips, the shape of a cube.
The granulated materials or chips are, after passage through a dust removal device, passed to an injection moulding machine.
Where granulated material is injection moulded, using heated extruder worms and heated nozzles, with application of pressure.

The temperatures used are between 220 and 255C, whilst pres-sures are from 50 to 100 kp/cm . The granulated material can be injection moulded into any desired shaped bodies.
The polylaurinlactam shaped bodies obtained in accordance with the method of the invention have excellent prop-erties, in which they are superior to the previously-known ~ polylaurinlactam materials.
- The mechanical and thermal properties of the material .
in accordance with the invention are collated in the following Tables I and II.

Table , Mechanlcal properties Measuring Dirnension Method ~ . . ... _ Yield stress ~S DIN 53,455 kp/cm 480 - 500 Elongation upon DIN 53,455 percent 28 - 36 yield stress ~S
Tearing strength ~R ISO R 527 kp/cm 550 - 670 ; Tearing elonqa-tion ER ISO R 527 percent 220 330 Modulus of elastlci-t~ E DIN 53,457 kp/cm 20000 - 24000 ; lO Para. 2.3 Limiting bending ISO R 178 kp/cm730 - 920 stress ~B

Notched bar impact DIN 53,453 kpcm/cm 70 - 84 I strength aK
Ball thrus-t hardness lO" DIN 53,456 kp/cm1030 - 1060 ¦
; _ Stage C _ l - --- -J

Table II
.

Thermal properties Measuring Me-thod I Dimension __._ _ _ ._ ._ Decomposition temp-lerature in the Depending on C~200 ~ 260 atmosphere recipe Melting tempera- VICAT ~ DIN C 194 ture 53,46 n Coefficient of linearat -600to 10 / C0.3 - 0.5 expansion ~ ~30 C

Coefficient of ther- kcal/m.h. 0.24 mal conductivity ~ - grd Temperature limits up to some hours o 210 of the use up to 4 months C 160 ¦up~7ards up to years C 135 ._ . _ __ . . _ .
The polylaurinlactam shaped bodies in accordance - 30 with theinvention stand out in an advantageous manner from the properties of previously know~ polyamides. In the Figs. 1 to 9 of the accompanying drawings, the properties of the product ~.:.il.ti&.~ ~

of Ihe presen-t lnvention are compared on the one hand with those of the polylaurinlactam product, us~d as starting ~t material, in accordance with German OffenlegungsschriEt No.
2,507,5~9 and on the other hand with those of other known polyamides such as polyamide 12, polvamide 11, polyamide 6.6 and polyamide 6. As can be seen , the product in accordancc ~ith the invention combines excellent elonclation upon yield stress, tearing strength, excellent modulus of elasticity, .. notched bar impact strength and ball thrust hardness with good yield stress, tearing elongation and limiting bending stress with extremely slight shri.nkage of the ma-terial.
Furthermore, the polylaurinlactam shaped bodies in accordance with the invention have excellent compressive strength. As shown in rig. 10 which, as the result of compression tests, is a force - upsetting diagram of the polylaurinlactam material in accordance with the invention.
To carry out the compression tests, five cubes obtained from the polylaurinlactam shaped body produced in accordance with the invention and having an edge length of 25 mm were used as test bodies which were tested using a universal testing machine 200 kN whilst adhering to a test climate of 23 C/50 percent relative air moisture and a deformation speed of 2.0 mm/min. The compression tests are reproduced in Table III.

3~ 9 Table III
Compression Tests _ I -- ---------r----------Test piece ~i /o 1~ ~s 2) ~10 o/o 3) 1 ~ s 4) No. N/mm N/mmN/mm i O/O
" . ._ _ .. __ _ ~; 1 17.01 45.76 ~8.73 2.71 2 15.95 45.23 56.74 2.91 3 17.44 49.5~3 61.81 2.91 4 17.~1 50.6t) 64.09 ~.95 ~ 5 17.68 46.73 57.97 2.91 - Average ]7.06 47.58 59.87 2.83 1) Compressive stress at 1 percent upsetting.
2) Compressive stress at upsetting limit, in which respect the upsetting limit was ascertained as the point of intersection of the two main equalising straight lines onto the curve (see Fig. 10).
` 3) Compressive stress at 10 percent upsetting.
.. ~
4) Elongation at upsetting limit.
As result of the compressive tests, in no test body was a failure or breakage ascertained during and after the tests.
The compressive test was terminated at a compressive force of 60 kN, or respectively at a compressive s-tress of about 96 N/mm .
The new polylaurinlactam shaped bodies in accordance with the invention are also distinguished by a high resistance to light energy radlation.
In a surprising manner it has furthermore been ascertained that the mechanical propertles of the polylaurin-lactam meterial in accordance with the invention are improved , by irradiation with light energy radiation. As can be seen from the following Table IV, four test pieces of the material in accordance with the invention were irradiated with Y-radia-tion.
-- 1.0 --Table IV
Irradiation of the polylaurinlactam material in accordance with the invention with Y-rays.

~ J
Irradiated material in accordance Energy dose with the invention ,~ I 1 not irradiated (1) 2 40 ~ 10 J/kg ~ 3 100 ~ 104 J/kg 4 200 ~ 10 J/kg :' !
(1) as comparison base value The irradiated test pieces 2 to 4 as well as the non-irradiated reference sample were tested with respect to their mechanical properties. The values obtained are reproduced in the following Table V.
Table V
Mechanical properties of the polylaurinlactam material in accord-ance with the invention after irradiation with Y-radiation.

Test Standard ¦ Unit ¦Reflerl 2 3 ~ 4 . _ _ I l , I
Shore D DIN 53505 _ 69 71 71 72 Tensile strength 2 at the flow limit DIN 53455 N/mm 50 52 55 54 Elongation at the flow limit DIN 53455 o/o 38 20 18 14 Breaking 2 strength DIiN 53455 N/mm 50 52 55 53 Breaking elongation DIN 53455 o/o 38 20 18 14 Bending-E-modulus DIN 53452N/mm21230 1425 1615 1735 Limiting bend- 2 ing strengthDIN 53452N/mm81 85 86 92 .. .__ .. _ .. _ ...

The increase in the mechanical properties of the poly-; aurinlactam material, in accordance with the invention, after erradiation with Y-rays is reproduced as a graph as a function of the ray dose in Fig. 11.

'~

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of producing shaped bodies of polylaurin-lactam, in which laurinlactam is melted, the molten mass is initially intermixed with a catalyst and then the mixture is mixed with an activator and is polymerised, the polymerised material is cast into threads or strands which consist of a polymer which does not melt upon the heating, but in the range from about 217 to 271°C decomposes in air and is no longer regenerable, the threads or strands are comminuted into granu-lated material or chips and the comminuted material is injec-tion moulded at temperatures from 220 to 255°C at pressures from 50 to 100 kp/cm2.

2. A method as claimed in claim 1, in which the injection moulding is effected at a temperature of 240°C in the rear region of a worm of a injection moulding machine and at 250°C in a front region of the worm of the injection mould-ing machine.

3. A method as claimed in claim 1, in which the addition of the catalyst and the subsequent admixture of the activator and the polymerisation are effected at a constant temperature from 150°C to 200°C.

4. A method as claimed in claim 3, in which the temperature is 160°C.

5. A process as claimed in claim 1, 2 or 3, in which equivalent quantities of the lactam are introduced into two separated boilers and melted at temperatures in the range below 190°C to above 160°C, a catalyst is introduced into the melt in one boiler and at a temperature below that of the first melt in the first boiler, an activator subsequently introduced into the melt in the other boiler with stirring, and mixing said melts while maintaining said temperature by pumping them through pipes with a maximum inclination to the horizontal of 10° to a mixing zone, said pipes having a volume which is at least one third greater than the delivery capacity of the pump.

6. A method as claimed in claim 1, 2 or 3, in which materials have an average particle diameter of 2 to 5 mm.

7. Polylaurinlactam shaped bodies having the follow-ing physical characteristics: a yield stress 6S, measured in accordance with DIN 53,455, from approximately 480 to approxi-mately 500 kp/cm2; an elongation, measured in accordance with DIN 53,455, upon yield stress .epsilon.S, from approximately 28 to approximately 36 percent; a tearing strength 6R, measured in accordance with ISO R 527, from approximately 550 to approxi-mately 670 kp/cm2; a tearing elongation .epsilon.R, measured in accord-ance with ISO R 527, from approximately 220 to approximately 330 percent; a modulus of elasticity E, measured in accordance with DIN 53,457 Para 2.3, from approximately 20,000 to approxi-mately 24,000 kp/cm2; a limiting bending stress 6B, measured in accordance with ISO R 178, from approximately 730 to approxi-mately 920 kp/cm2; a notched bar impact strength aK, measured in accordance with DIN 53,453, from approximately 70 to approxi-mately 84 kpcm/cm2; and a ball thrust hardness 10", measured in accordance with DIN 53,456 stage 6, from approximately 1,030 to 1,060 kp/cm2.