DE1694494B2 - Flame-resistant nylon composition - Google Patents

Description

Although nylon is self-extinguishing when unfilled is. Filled nylon generally exhibits flammability, which is dangerous can. This is particularly the case with fillers 10. which improve the mechanical properties of nylon improve at elevated temperatures, e.g. B. that. Mica and asbestos. It is therefore advisable to use in nylon compositions containing such fillers incorporate flame retardant additives. A flame retardant additive that is suitable for nylon. muli can withstand the processing temperature of nylon without decomposition. For nylon-6 and -610 These are generally in the range from 220 to 230 C and for nylon-66 at about 290 C.

One of the most effective methods of achieving flame resistance in polymers in general is the incorporation of halogenated additives which liberate halogen acids at the firing temperatures. These acids react with the OH radicals. which propagate the burning celiac reaction, and in removing them they tend to extinguish the flame. In most of them, however, sirous substances of halonized additives are required for rapid flame extinction. 1 R-PS 1439 030 states that compounds of arsenic. Bismuth and antimony, especially their oxides, act synergistically with halogenated additives and greatly reduce the concentration required to achieve effective flame resistance of the polymers. A major disadvantage of these materials is their toxicity. For example, in "Dangerous Properties οί Industrial Materials" by N. Imnii Sax (p. 454. 2nd edition. 1963. Reinhold. New Yorki antimony compounds with regard to the chronic as well as acute yellowing hazards are rated with "3" ld. Iv. Cause them an iodine or permanent damage in a short time and in small quantities). This makes handling both difficult and dangerous during manufacture and fabrication. Toxic ' ¹ Vapors also graze' developed when / together. which contain these compounds. .1 u 1 riammcntcmpeuUii en gehrachi be

It has now been found that in nylon instead of the aforementioned arsenic. Bismuth and limestone oxides Zinc oxide can also be used to make nylon compositions with good flame resistance to manufacture. Because zinc oxide is not toxic. this eliminates the disadvantages of antimony. Bismuth and arsenic oxide eliminated. Is striking. that zinc oxide only synergizes with the nylon in nylon shows mentioned halogen compounds. This can be seen from the comparative examples below emerged.

The subject of the invention is therefore <_ ■. flame resistant Nylon fusing. Consists of 45 to 90 percent by weight nylon. 0 to 45 percent by weight Filler. 5 to 30 percent by weight of a metal compound and 5 to 25 percent by weight of one halogenated additive that is thermally stable at the manufacturing temperature of the nylon. but with A halogen acid can release flame temperatures, which is characterized by this. that the metal compound consists of zinc oxide.

The Hamm-resistant according to the invention is preferably used Nylon composition of 50 to 90 weight percent nylon. 20 to 40 percent by weight filler. 5 to 20 percent by weight zinc oxide and 5 to 15 percent by weight halogenated additive.

The filler can be any filler such as e.g. B. Asbestos. Mica or fiberglass, as they are normally used to improve mechanical properties used by nylon.

By nylon is meant a synthetic polyamide, in particular a polymer or mixed polymer of 1 lexamethylene adipamide (nylon-66). Hexamethylene sebacamide (Nylon-610). Caprolactaml nylon-6). Lindecanolactam (Nylon-! 1) or dodecanolactam (nylon-12) od'T a mixture of such materials with one another or with other polyamides, such as. B. Polyhexamethylene decrephalamide.

A number of halogenated additives useful as flame retardant additives are disclosed in US Pat French patent 14 39 030 described. Such an addition has the structure

Cl

/ 'K

Cl \>

Cl Cl

, 'Cl

Cl \

Cn Ci

This addition is in the present description as C, _{K H: denotes:} CI. ₁ This compound has the advantage that it is stable at the temperatures required for nylon processing.

The synergistic effect of zinc oxide au Ci.Jl ^ CI ,, as a lamb retarder in Pohmerzusam Inense'zungen is apparently special for nylon Art. If, for example, zinc oxide mi C'n, 11i -. < "1, -. Was mixed and in a number of voi other synthetic pol ν kidneys was incorporated then this combination did not have a noticeable lanimver / Ögei ung effect on the predominantly ' Number of polymers: in some cases, di> \ Induction scivAindigkeil also enlarged. However, a mixture of zinc oxide is used

CsH ₁₂ Ci _{12 has} a very remarkable lamb-inhibiting effect, although zinc oxide itself has no noticeable effect on the rate of combustion. This combination of C ₁₁₄ H ₁₂ CIp and zinc oxide was a flame-retardant additive that, because it was better acidic than C ₁ ) (H ₁₂ CI, ;; itself.

It is true that there is a large range of amounts of CmH ₁₂ Cl ₁ and zinc oxide that give good skin resistance, but the optimal concentrations of any substance ultimately depend on the change in mechanical properties. that can be tolerated. C ₁₈ H ₁₂ Cl ₁ , acts as a plasticizer. Thus, when the amount of C _1x H ₁₂ CI _{12 is} increased, there is a tendency that the melt composition and the tensile strength are reduced but the impact strength of nylon is increased. Zincoid, on the other hand, acts as an inert filler. With an increase in the concentration of zinc oxide, the enamel is increased, while the impact strength and tensile strength are generally reduced, but the reduction in tensile strength with zinc oxide is not as pronounced as with C ₁₁₄ H ₁₂ CI ₁₂ . In general, the preferred composition contains 5 weight percent zinc oxide and 10 weight percent C ₁₁₄ IIpCIp.

A preferred nylon composition contains polymerized caprolactam units of the form!

[NH-CH ₂ -CH ₂ CH ₂ CH ₂ -CH ₂ -CO-]

as well as nylon-66, the units of the following formulas

[NH CU ₂ -CH ₂ CH ₂ CM ₂ -CH ₂ -CH ₂ -NH-]
and

I CO CH ₂ CH ₂ -CH ₂ CH ₂ -CO-]

which can be obtained from hexamethylene adipamide or adipic acid. Such a composition can be a nylon 66 6 mixed polymer, with individual polymer chains caprolactam units as well as hexamethylene adipamideinhciten, or a nylon-66 nylon-6 mixture be described, Polycaprolactam celts are mixed with polyhexamethylene adipamide chains. When the two Homopolymcrcn are mixed together, then can the resulting composition is a blend of nylon 66 homopolymer, nylon 6 homopolymer and Nyion 66/6 Misehpolymer. The exact nature is not essential to the present invention. Contains in particularly preferred compositions the nylon 2 to 5 (preferably 3) percent by weight polymerized caprolactam units and 98 to 95 (preferably 97) percent by weight polymerized ethylene adipamide units.

To enable glass-filled nylon-66 to be extruded, a melt temperature of at least 290 ° C is usually required. This is close to the decomposition temperature of (10 C _1H HpC "lp. By incorporating 2 to 5 percent by weight of polymerized caprolaetamine units into the composition, a melting temperature of 275 C can be obtained, reducing the risk of decomposition of the C ₁₈ H ₁₂ Cl ₁₂ The lower melting temperature is made possible by an amendment of the composition, which is presumably due to a reduction in the crystallinity of the nylon composition.

The incorporation of a small amount of polymerized caprolactam units has other advantages, because of a better surface finish without a significant loss of the high tear strength of Nylon-66 is achieved.

Another advantage of using a low melting temperature is that glass and flame retardant additives can be mixed with the nylon in a single extrusion process. It has been found to be extremely difficult. to achieve this using nylon-66, the normal process of which is to mix in the glass through a first stage extrusion, the temperature of which is normally above 300 ° C, and the flame retardant additive (e.g. C ₁₁₄ H ₁₂ Cl ₁₂ ) and zinc oxide to be added in a subsequent extrusion. While this double extrusion process reduces additive degradation, it is economically undesirable.

It has been found that when using the compositions which contain 2 to 5 percent by weight of polymeric caprolactam units, instead of a composition which is based exclusively on nylon-66, a higher throughput is possible. A 2-3% increase in performance was obtained. It has been found that lubricants (such as ¹ ₂ weight percent stearic acid.) Are useful for reducing the Tempei atur during extrusion of the nylon 66 composition; they can also be used to advantage with the nylon 6,6 copolymers or blends described above.

To illustrate the invention, the following are made Examples are given which represent a number of compositions describe which according to ASTM D-635-56T U956) (standard fiammabilily read for rigid plastics) were tested by burning, whereby however the network specified in the test was not present. Granules of various compositions were processed by injection molding into disks 3.2 mm thick. Samples from 127.0 χ 7/12 χ 3.2 mm were cut from the slices, with the long axis horizontal and the transverse axis in at an angle of 45 to the horizontal with the help of a clamp at one end and in at a distance of 25.4 and 101.6 mm from the free end. A non-luminous Bunscnbrcnnerflainmc (25 mm long) was held on the free end of the sample for 30 seconds and then removed. If the sample has stopped burning, get it The 25.4 mm mark was reached, then the flame was slid down for another 30 seconds. If the burning did not reach the first 25.4 mm mark after both burning attempts, then it was the sample classified as "non-burning". if if the burn reached the first mark, but the second (101.6 mm) mark did not, then the sample was considered to be Classified as "self-extinguishing".

The following examples 1 to 3 and 7 to II illustrate The invention. Examples 4 to 6 are included for comparison.

example 1

A sample of a gas-filled nylon 66 assembly the 1 part fiberglass to 2 parts

Nylon-66 containing was tumbled with the additive (zinc oxide and Ci ₈ H ₁₂ Cl ₁₂ I in the amounts shown in the table. The mixture was then extruded in a 31.8 mm screw extruder at a temperature of 290 ° C. The resulting extrudate was cut into granules. The granules were injection molded according to the ASTM specification mentioned above to prepare test samples. For the self-extinguishing and non-burning samples, the results are averages of 10 samples, and for the burning samples, the mean values of 3 samples.

additive Burn time (Sec.) first / «E-tes Burn ii scorch (Weight. Hexogenic on the Composition) No addition 335 10% zinc oxide 220 - 10% C ₁₈ H ₁₂ Cl ₁₂ 52 49 10% zinc oxide and 6th 6th 10% C ₁₈ H ₁₂ Cl ₁₂

Burning length drip behavior

(mm) Classification by ASTM D-6.15

> 127 frequent drops burning (13.5 mm'min)

> 127 frequent drops burning (20.8 mm min)

30.4 occasional dripping, self-extinguishing

10.2 not a drop not burning

B e i s ρ i e 1

Compositions were prepared and tested as described in Example 1, except that pentabromotoluene was used in place of C ₁₈ H ₁₂ Cl ₁₂ .

additive

Burning time (sec. I burning length T ropf \ -Thalien

Kinstufurm through ASIM D-635

15% pentabromotoluene
15% pentabromotuene
and 5% zinc oxide

first
Scorch / far
Scorch I mm ι ρ i e 1 ge 93 24 27.9 ke 4th 6th 15.2 3 By S

occasional dripping self-extinguishing no dripping non-burning

A composition containing 1 part glass and 2 parts N> Ion-66 was prepared. Ct ₈ H ₁₂ CI ₁₂ and zinc oxide were added in various amounts and the burning test was carried out as above.

additive

% C ₁₁₁ H ₁₂ CI ₁₂

% Zinc oxide

Calorific value (sec.)

first
Scorch

/ far
Burning burners

Drip process

Classification by ASTM D-635

0 0 340 4.3 > 76 frequently burning 10.6 (13.5 mm / min) 0 5 320 11.0 > 76 frequently burning 3.8 (20.8 mm / min) 0 10 210 49 > 76 frequently burning 2.6 (21.9 mm / min) 5 5 25.5 3.2 13.8 none not burning 5 K) 28.2 2.9 12.7 nearly not burning 5 15th 26.4 2.5 11.5 none not burning 5 20th 11.9 6.7 10.2 none not burning IO 0 52 1.9 30.5 nearly self-extinguishing 10 5 8.4 3.2 10.2 none not burning 10 H) 9.6 Ί "1 10.9 none not burning 10 15th 4.7 9.6 none not burning IO 20th 4.0 8.H none not burning 15th 0 44.1 6.0 nearly not burning 15th 5 4.2 10.9 none not burning 15th IO 3.0 10.9 none not burning 15th 15th 3.1 10.2 none not burning

Examples 4 and 5 (Comparative example c)

Test samples were made according to ASTM D-635-62T produced, the polymethyl methacrylate molding powder (Example 4) or a terpolymer made of acrylonitrile. Butadiene

and styrene (Example 5) with various amounts of C ₁₈ H ₁₂ CI ₁₂ and zinc oxide. The samples were prepared by dry drumstick and dried at 80 ° C in an oven overnight before being injection molded. The results of the firing tests are given below.

example

Added percent by weight Ci _{11 HoCI 1} , zinc oxide

O
IO
10

O
10

0
10

0 IO 10

IO

10

Burning shrinkage wedge

(mm mini

33 38 51 46 46

51 56 56 51 liinstufunp
gemüM
ASTM D-635

burning
burning
burning
burning
burning

burning
burning
burning
burning

Color of the pellet

transparent, good

opaque, white

opaque, white

opaque, very pale brown

opaque, white

opaque, very dark yellow / brown
opaque, very yellow / brown
opaque, pale buff
opaque, pale buff

Example 6 (Comparative example)

Test samples were made from compositions containing polypropylene with the following Table contained additives. The results of the burning tests on these samples were as follows:

C ₁₁₁ H ₁₂ Cl ₁₂

additive
Weight percent

Zinc zinc anti

oxj'd chloride mon-

ox vd

Different

Amounts up to
to 20%
23

0
0

10 10 15th IS 20th 0

0
0
0
0

0
0

0 0 0 0 0 10

Burning speed

25-38 mm min. 25-38 mm min

51 mm min 51 mm min 51 mm min 51 mm min 51 mm min self-extinguishing

Example 7

stretched. The results are given in the table below. For comparison, samples that contained no / usiitzc, extruded and processed in the same way as the filled samples.

35

40

45

so

55

A composition comprised 1 part of 2 parts of glass fibers wound nylon, was charged with C ₁₈ H _{12 Cl:} packed in the specified amounts in the table and zinc oxide. The mixtures were then extruded as described in Example 1 and viscosity, tensile strength and unnotched impact strength measurements were made on the samples thus prepared. The sample for the Charpy impact test was an unnotched sample of 50.8 3.2 8.9 mm. The impact occurred on the center of the 8.9 χ 50.8 mm side. The sample for measuring the tensile strength had a stretching zone with the dimensions 63.5 12.7 χ 3.2 mm and was made with a speed of 1.52 msec

Weight percent additive
C ₁₁₁ H ₁₂ CI ₁₂ zinc
oxide 0 viscosity
at
1 (K) see '
285 C
103 poise Tensile strength
wedge
MN m ² Impact resistant
wedge
unguarded
I crrr 0 0 1.7 131 1.66 10 10 1.0 116 2.71 10 20th 1.8 108 1.75 Kl 20th ·> -> 97 1.43 112 1.51

Examples 8-11

The composition contained nylon and glass fibers in a ratio of 2: 1. and the flame retardant additives were 10 percent by weight C ₁₈ H ₁₂ Cl ₁₂ and 5 percent by weight zinc oxide, the total composition being nylon. Glass and additive made up 100 percent. In Examples 8 and 10, as shown in the table, the nylon was nylon 66 homopolymer. while in Examples 9 and 11 the nylon was a copolymer of nylon-66 (97 weight percent) and caprolactam (3 weight percent). The copolymer was prepared by adding the caprolactam to an aqueous solution of hexamethylene diammonium adipate and polymerizing the mixture in an autoclave in the usual manner. The nylon, glass, zinc oxide and C ₁₈ H ₁₂ Cl ₁₂ were mixed using a 3 inch bore, ventilated extruder using one of the following methods as shown in the table.

509527/37

QQII

Method Λ

The fiberglass and nylon were first extruded using a ventilated extruder according to η of British Patent 9 50 656 described method mixed. The glass fibers were the Extruder fed in the form of continuous rovings. The egg extrudate was cut into granules, which were then fed to the extruder together with the flame-retardant additives in order to produce a To produce extrudate that has been reprocessed into granules.

Method B.

In this method, nylon, continuous glass rovings, and the flame retardant additives were all lined up at the same time fed to the feed opening of the extruder. The extrudate was cut into granules as before.

The highest temperatures of the melt were in the compression zone. These temperatures together with the details of screw speed and throughput are in the following Table given.

example

nylon

66
66/6
66
66 6

method

Λ
Λ
B.
B.

Melting temperature Snails Salt through description speed of the product I Cl IIi mini (kg SlI 290 300 100 59 bright color. somewhat porous 275 110 75 bright color, somewhat porous 320 330 145 S6 dark colour. highly porous 285 145 H6 bright color, somewhat porous

The extruded compositions of the above table were then molded in test samples, wherein a tendon injection molding machine was used. The flammability tests were carried out according to ASTM D-635 executed. The results are given below along with the results with tensile strength measurements.

example tensile strenght Burn time second Brennliinge Drip behavior classification first Scorch Scorch (Sec. I IMN no | (Sec.) 6.0 inrnl 8th 114 5.7 5.7 6th not not burning 9 113 6.1 7.5 7th not not burning 11th 116 5.7 7th not not burning

The composition of Example 10 was of such poor quality that no tensile strength wedge or Burn attempts have been carried out.

Claims (2)

Patent claims: 1. A flame retardant nylon composition consisting of 45 to 90 weight percent nylon. 0 to 45 percent by weight, nt filler, 5 to 30 percent by weight a metal compound and 5 to 25 percent by weight of a halogenated additive, which is thermally stable at the manufacturing temperature of the nylon. but at flame temperatures can set a halogen acid free, thereby characterized in that the metal compound consists of zinc oxide. 2. Composition according to claim 1, characterized in that it consists of 50 to 90 percent by weight Nylon. 20 to 40 percent by weight filler. 5 to 20 weight percent zinc oxide and 5 to 15 weight percent halogenated additive consists.