FR2503719A1 - PROCESS FOR MANUFACTURING POLYLAURINELACTAM MOLDED BODIES AND MOLDED BODIES OBTAINED BY CARRYING OUT SAID METHOD - Google Patents

Abstract

POLYLAURINELACTAM OBTAINED BY POLYMERIZATION BY MELTING LAURINELACTAM, MIXING THE MELT MASS WITH A CATALYST AND ADDING THE MIXTURE OF AN ACTIVATOR, THEN FLOWED TO FORM WIRES OR BLUGS, IS FRACTIONED, IN ACCORDANCE WITH THE PELLETS OR CHIPS, AND IS MOLD BY INJECTION AT TEMPERATURES BETWEEN 220 AND 255C UNDER PRESSURES BETWEEN 50 AND 100KGFCM. THE MOLDED BODY THUS OBTAINED IS CHARACTERIZED BY SUPERIOR PHYSICAL PROPERTIES.

Description

i Process for manufacturing molded bodies made of polylaurinelactam

  and molded bodies obtained by implementing this process.

  The invention relates to a method for manufacturing molded bodies made of polylaurinelactam, as well as the molded bodies.

obtained by this process.

  There is known from United States Patent No. 3,793,255 a process for manufacturing molded bodies by activated anionic polymerization of laurinelactams, in

  which two lactam melts are added separately

  ment of a catalyst and an activator, being

  supplied with nitrogen and then brought to a device

  tif mixer by separate pipes brought to the

  same temperature as the melt to flow in

  following in a mold; on the route to the device

  Mixer, partial melts are brought through

  pour respectively a system of coils analogous to

  a siphon. Characteristics of the polymer are thus obtained.

  risat totally deviating from the usual polycaprolactam.

  The drawback of this process lies in the fact that it is certainly possible to obtain polymerized cast products which can be used at the start, but whose properties deteriorate very strongly at

after a short time.

  We know, from German Patent Application DE-OS 25 07 549, a process for manufacturing bodies molded in

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  polylactams, in particular polylaurinelactam, in which the monomeric lactam is melted, the melt is first

  mixed with a catalyst, the mixture thus obtained is added

  activated and the polymerized product is then immediately poured into molds. A modification of this process is described in German Patent Application DE-OS 25 59 749, according to which molded bodies made of polylaurinelactam are produced by adding a polymerization catalyst to a partial melt of lactam held in a separate tank and stirring at a temperature above 1600 C and below 1700 C; then the mixture is stirred and, with a time difference, an activator is added, while mixing, to an equivalent partial melt of lactam held in a separate tank and at a temperature a few degrees lower than that of the first mass melted, but also included in a range below 1700 C and above 160 C; we stir, then the molten masses are drawn from their tanks

  by a gear pump while maintaining

  naked at their temperature; from there they are brought, by

  slightly inclined pipes with a volu-

  mique at least 1/3 higher than the pump flow, at a mixing zone where they are mixed between 1700 and 1750C, then injected without pressure or at low pressure by

  an injection head, or else they are cast.

  The polylaurinelactam products obtained according to German Patent Applications DE-OS 2 507 549 and 2 559 749 have the following physical characteristics:

  an elastic limit aS measured according to DIN 53 455 included in

  be around 470 and 520 kgf / cm2; an elongation at the elastic limit Es, measured according to DIN 53 455 of between 17 and 25%;

  a tensile strength aR # measured according to ISO R 527,

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  catch between 500 and 630 kgf / cm2; an elongation at break ER, measured according to ISO R 527, of between 200 and 300%; a modulus of elasticity E, measured according to DIN 53 457 Ab. 2.3, between approximately 19,000 and 22,000 kgf / cm2; a bending limit stress aB measured according to ISO R 178, between 750 and 1000 kgf / cm2; an impact resistance on ak notched bar measured according to DIN 53 453 between 55 and 65 kgf.cm/cm2; a 10 "ball hardness measured according to DIN 53 456 C scale, between 1000 and 1050 kgf / cm2; an abrasion resistance measured by means of a tabler abrasion device between 158 and 129 mm3 / turns min .; an elongation over time to 1/1000 (23 C / 95%) measured according to DIN 53 444 between 50 and 60 kgf / cm2 approximately; and a creep modulus Ec / 1000 (a20.0) measured according to DIN 53 444,

  between approximately 13,000 and 14,000 kgf / cm2.

  We know, on the other hand, from the German Patent Application

  mand DE-OS 26 02 312, a wire casting installation, in which the mentioned polylaurinelactam melts

  higher can be cast in the form of wires.

  The object of the invention is to provide a simple and easy-to-implement process which makes it possible to obtain molded bodies of polylaurinelactam having physical properties.

improved.

  We were surprised to find that if the polylaurinelactam known from the previously cited patents, which does not melt

  when heated, but decomposes in air in a range

  taken between 217 and 271'C and can no longer be regenerated, is

  distributed to form granules and if this granular material

  the strips are injection molded to form molded bodies, products having new improved properties are obtained.

  The invention provides a method for manufacturing soft bodies.

  strips of polylaurinelactam, in which the laurinelactam is melted, the melt is first mixed with a catalyst,

  and then the mixture is added with an activator and poly-

  merited, this process being characterized by the fact that the ma-

  material during polymerization is poured in the form of wires or tubes, made up of a polymer which does not melt when heated, but decomposes in air between 217 and 2710C and can no longer be regenerated, only the wires or tubes are fractionated in a known manner into granules or chips and the fractionated material is injection molded

  at a temperature between 220 and 2550C under a pressure

  sion between 50 and 100 kgf / cm2.

  Another object of the invention relates to bodies molded in

  polylaurinelactam obtained according to the above process.

  The molded bodies of polylaurinelactam of the invention pre-

  feel the following physical properties: an elastic limit as measured according to DIN 53 455 of between 480 and 500 kgf / cm2, approximately; an elongation at the elastic limit Es measured according to DIN 53 455 of between 28 and 36%, approximately; a tensile strength aR measured according to ISO 527 of between 550 and 670 kgf / cm2, approximately; an elongation at break sR measured according to ISO R 527 of between 220 and 330%, approximately;

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  a modulus of elasticity E measured according to DIN 53 457 Ab. 2.3, between 20,000 and 24,000 kgf / cm2, approximately; a bending limit stress aB measured according to ISO R 178 of between 750 and 920 kgf / cm 2 approximately, an impact resistance on a notched bar a k measured according to DIN 53 453 of between 70 and 84 kgf.cm / cm 2, approximately; a 10 "ball hardness measured according to DIN 53 456 scale C,

  between 1030 and 1060 kgf / cm2, approx.

  The starting material used to carry out the process of the invention is the polylaurinelactam obtained according to German Patent Application DE-OS 2 507 549 or

DE-OS 2 559 749.

  To make the starting material, we first melt

  laurinelactam and mix the cataly-

  sister. After carefully mixing, the activa-

  mixture. Adding the catalyst to the laurin lactam melt, then mixing the activator and

  polymerization is preferably carried out at constant temperature

  aunt, suitably between 150 and 2000C, a temperature

  ture of 1601C having proved optimal.

  We can also proceed, according to the German Patent Application.

  mand DE-OS 2 559 749, by putting equivalent quantities of laurinelactam in two separate tanks and making them

  melt with stirring. Maintaining a lower temperature

  re at 1700C and above 1600C, a catalyst is introduced into a tank and stirred. With a time difference from this operation, we add in a separate tank

  containing an equivalent amount of laurinel melt-

  activates an activator, with stirring, at a lower temperature

  from a few 'C to that of the first melt, but always

  however below 1700C and above 160'C. The two contents of the containers are then respectively withdrawn

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  of their tanks, while being kept at their temperature, by a gear pump and are sent by the two pumps, via pipes inclined horizontally at most 10, to a mixing zone, the pipes having a volume dimension greater by at least a third than that corresponding to the flow rate of the pump. The material is briefly mixed in the mixing zone.

  In accordance with the invention, the material being polymerized

  rization is immediately poured to form threads or

  sausages. For this operation, you can use the installation

  yarn casting described in German patent DE-PS 2 602 312. The yarns or strands are then split

  to form pellets or chips.

  For example, the wires or strands may first be trans-

  formed by cylinders in ribbons which are then cut into strips, then finally fractionated into granules. To grind the starting polymer, it is possible to use the usual mills or pellet machines. The granules can, at will, have regular or irregular shapes. For example, the granules used have a rectangular, more especially square, cross section. Preferably, the granules used have an average particle diameter of 2 to mm. Dice-shaped granules with 3 mm sides

  have proven to be particularly favorable.

  The polylaurinelactam granules obtained in the context of the invention are then injection molded. Temperatures from 220 to 2551C are used here as well as pressures from 50 to 100 kgf / cm2. The molding operation can

  be carried out with conventional injection molding machines

  tion with heated nozzles and extrusion screws. Preferably, the rear area of the screw is heated to 2400C,

  while the anterior area of the screw is heated to 250 ° C.

  The heating of the nozzle is preferably done at 250 ° C.

  The manufacture of the molded body in polylaurinelactam can

  for example, proceed as follows.

  A polymerization product as obtained according to the process described in German Patent Applications DE-OS 2 507 549 or DE-OS 2 559 749, from laurinelactam, is brought to the state during polymerization, preferably between 1600 and 1680C, at a wire casting installation. Appropriately, the material being polymerized is brought by a pump to the installation produced in the form of a flow crosspiece for the continuous casting of wires or

  sausages. From the casting plant, the, product of

  the polymerization is then in the form of a flowable fluid material

  forms and passes over a semi-open gutter, for example in the form of a fluid plastic wire with a round profile, and goes to a cylinder mixer, the interval between cylinders of which can vary continuously, and it is brought there to the desired thickness and width. The strip leaving the interval between cylinders by a guide groove is then cut into parallel strips during its passage

  on knife cylinders, which are then split

  operated by a knife head from a knife cylinder

  assembled afterwards, to form granules or shavings.

  For example, if the strips have a square cross section, the granules have a cubic shape. The granules or shavings, after passing through a dedusting device,

  are brought to an injection molding machine. The material

  The granulated riau is then injection molded using extrusion screws and heated nozzles and putting in

  pressured. The temperatures used are inclusive

  its between 220 and 2550C and the pressures used are com-

  taken between 50 and 100 kgf / cm2. The granules can be soft

  strips by injection to form all the desired molded bodies.

  The molded polylaurinelactam bodies obtained with the process

  dice of the invention are characterized by remarkable properties

  quables which are far superior to that of materials in

  polylaurinelactam known until now.

  In the following Tables I and II are grouped the

  mechanical and thermal properties of the product of the invention.

TABLE I

  Mechanical properties Measurement method Dimension Elastic limit CS

Elongation at the limit

  elastic elastic ES Tensile strength R Elongation at break óR Modulus of elasticity E Bending limit stress B Notch resistance ak Ball hardness 10 "

DIN 53 455

DIN 53 455

ISO R 527

ISO0 DIN Ab. R 527

53,457

2.3

ISO0 R 178

DIN DIN

53,453

53,456

  step C kgf / cm2 kgf% / cm2 kgf / cm2 kgf / CM2 kgf / cm2 / kgf / cm2 kgf / cm / cm2 kgf / cm2

480-500

28-36

550-670

220-330

20000-2400

730-920

- 84

1030-106 (

)

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TABLE II

  The molded bodies of polylaurinelactam of the invention are available

  advantageously feature properties of the polyamides known hitherto. In the appended figures 1 to 9, the properties

  of the new product are compared on the one hand with those of the pro-

  polylaurinelactam product used as starting material according to Patent Application DE-OS 25 07 549 and on the other hand, to those of other known polyamides such as polyamide 12, polyamide 11, polyamide 6.6 and polyamide 6. As we have seen, the product of the invention combines an elongation at the elastic limit, a tensile strength, a modulus of elasticity, an impact resistance on a notched bar and a remarkable ball hardness with a good limit. elastic, good elongation at break and good bending stress, as well as material shrinkage Thermal properties Measurement method Unit Value Temperature of des- according to the formula oc 200-260

truction in the-

  mosphere VICAT B DIN oC 194 melting temperature

53,460

  Coefficient of expansion - 60 to 10 / C 0.3-0.5 linear tation a + 300C Coefficient of conductive- kcal / 0.24 thermal activity --.h.grd Temperature limits Up to a few 0C 210 d ' use according to the preceding hours Up to 4 months 00C 160 Up to years 0C 135

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extremely weak.

  The molded bodies of the invention are further characterized

  by remarkable resistance to compression. On the fi-

  gure 10 attached is reproduced as a result of

  compression, a crushing diagram as a function of the

  these exercises for the polylaurinelactam product of the invention

  tion. To carry out the tests,

  vettes five cubes of 25 mm c8té obtained from a molded body in polylaurinelactam manufactured according to the invention

  which are tested using a universal testing machine-

  200 kN, maintaining a test atmosphere of 231C / 50% relative air humidity and a deformation rate

  2.0 mm / minute. Compression results are collected

wheat in Table III.

TABLE III

  Compression tests 1) compression stress for 1% crushing; 2) compressive stress at the crushing limit, the

  crush limit being obtained as an inter-

  Sample NI 'i% 1) as 2) a 10% 3) Es 4) N / mm2 N / mm2 N / km2%

1 17.01 45.76 58.73 2.71

2 15.95 45.23 56.74 2.91

3 17.44 49.58 61.81 2.91

4 17.21 50.60 64.09 2.95

17.68 46.73 57.97 2.91

Average 17.06 47.58 59.87 2.88 il

  section of the two main balancing lines or tan-

  main slopes at the curve (see diagram in figure 10); 3) compression stress for 10% crushing;

  4) dilation to the crushing limit.

  The result of the compression tests is that no

  tee neither collapse nor rupture, during or after the tests,

on no test piece.

  The compression test was completed at a compression force

  of 60 kN, and a compression stress of around 96 N / mm2.

  The new molded bodies of the invention in polylaurinelacta-

  me are also characterized by high resistance to

high energy radiation.

  We were surprised to note, moreover, that the pro-

  mechanical properties of the material of the invention in polylaurine-

  lactam are improved by high energy irradiation.

  As can be seen in the following table IV, we have irradiated by

  Y radiation four samples of the material of the invention.

TABLE IV

  Irradiation of the material of the invention in polylaurinelactam by y-rays Material according to the invention irradiated Energy dose 1 not irradiated (1) 2 40. 104 J / kg 3 100. 104 J / kg 4 200. 104 J / kg

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1) base value for comparison.

  The irradiated samples 2 to 4, as well as the non-irradiated comparative samples, were subjected to tests to determine their mechanical properties. The values obtained

  are reproduced in Table V below.

TABLE V

  Mechanical properties of the material of the invention in polylau-

  rinelactam after irradiation with y-rays.

  Test Standard Unit 1 2 3 4 Comparison

D 69 71 71 72

  Tensile strength creep limit DIN 53455 N / mm2 50 52 55 54 Expansion at creep limit DIN 53455% 38 20 18 14 Tensile strength DIN 53455 N / mm2 50 52 55 53 1 long break DIN 53455 % 38 20 18 14 at break Bending module DIN 53452 N / mm2 1230 1425 1615 1735 Bending limit stress DIN 53452 N / mm2 81 85 86 92

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  The increased mechanical properties of the material

  the invention in polylaurinelactam after irradiation with ra-

  yons is reproduced in Figure 11 as a diagram

  depending on the radiation dose.

Claims (5)

Claims.   1. Process for manufacturing molded bodies of polylaurinelac-   tame, according to which laurin lactam is melted, then the melt is mixed with a catalyst, the mixture then being added with an activator and polymerized, characterized in that the material being polymerized is poured to form threads or tubes formed by a polymer which does not melt under heat, but which decomposes in air in the range from 217 to 2710C and cannot   no longer be regenerated, in that the wires or strands are broken   worked in a manner known per se to form granules or chips and the fractionated material is injection molded   at temperatures between 220 and 2550C under pres-   sions between 50 and 100 kgf / cm2.   2. Method according to claim 1, characterized in that the granules used have an average particle diameter between 2 and 5 mm.   3. Method according to claim 1 or claim 2, characterized in that one works at a temperature of 2401C in the rear region of the screw of the molding machine by   injection and at a temperature of 2500C in the anterior zone machine screw.   4. Polylaurinelactam molded body obtained by processing   of the method according to any one of claims 1 to 3.   5. Molded body of polylaurinelactam obtained by processing   the method according to any one of claims 1 to 3,   and having the following physical characteristics: an elastic limit aS measured according to DIN 53 455 of between approximately 480 and approximately 500 kgf / cm2; an elongation at the elastic limit ES measured according to DIN 53455 of between 28 and 36%, approximately; a tensile strength cR measured according to ISO 527 of between 550 and 670 kgf / cm2, approximately;   an elongation at break FR measured according to ISO R 527 com-   taken between 220 and 33 (c / 0, approximately; a modulus of elasticity E measured according to DIN 53 457 ab. 2.3 between 20 and 24,000 kgf / cm2, approximately; a limiting bending stress aB measured according to ISO0 R 178 included between 750 and 920 kgf / cm2, approximately; an impact resistance on ak notched bar measured according to DIN 53 453 between 70 and 84 kgf.cm / cm2, approximately; a 10 "ball hardness measured according to DIN 53 456 scale C ,   between 1030 and 1060 kgf / cm2, approx.