DD271334A1 - STABILIZER AND FLAME PROTECTION FOR POLYAMIDE - Google Patents

Abstract

The invention relates to a stabilizer and a flame retardant for polyamide. The stabilization of polyamide 6 against changes in the viscosity of the melt in the production of large moldings and the equipment of the polyamide with a flame retardant is achieved by adding only one component, if the melt of the polyamide 5 to 10% Benzoesaeuresulfimid added.

Description

Characteristic of the known state of the art According to the increasing safety requirements are increasingly design and Required finished parts, which are flame retardant and have self-extinguishing properties. This will be in case of fire Fire spread prevented. Polyamide 6 molding compounds do not meet these requirements. Therefore, the flammability of Poiyamid-6 molding compounds reduced by the addition of special flame retardants. There are a variety of

technical solutions. The use of halogenated flame retardants, their effectiveness by the addition of

Metalloxidone, z. As antimony trioxide is excreted exudes, since the electrical utility properties (e.g. Tracking resistance) of the molded parts are minimized by these combinations. In case of fire, corrosive forms Hydrogen halide compounds, the other unpleasant 'jhnische consequences to the surrounding or adjacent Cause moldings. Halogen-free flame retardant cambinatiopon are known to comprise five groups of substances, the first group being '- Triazine compounds (melamine) - in particular recommended for polyamides According to DD 74097 or 135207 the Use of up to 60% melamine, based on polyamide. In particular, the achieved mechanical properties are sufficient

They do not meet the new requirements and require close processing levels in the production of molded parts and lead to success

Dyeing, especially in the shade of gray, for considerable reduction of the impact strength. The second group comprises flame retardant combination with red phosphorus. The excellent effect of this However, in addition to the inherent red color combination has the disadvantage that during the thermoplastic ι processing toxic Hydrogen phosphides are formed and released. The third group contains salt-like organophosphorus compounds or combinations with phosphorus salts

(DE 2806049,2915116,2810549,2523145, J 50075657,50085654, EP 37383), whereby the creep resistance is lowered considerably.

The fourth group is based on alkali and alkaline earth salts of organic monornaror and polymeric sulfenic acids (DE 2918534.

2458510, US 3888822), which also affect the performance of the material.

In the fifth group oxides, borates and other organic compounds are detected (US 3985928.4036806, DE 2628902). The flow behavior of polyamide melts, which essentially determines the processing behavior, is determined by temperature, Shear stress, shear rate, mean relative molar mass and polycondensation weight. Essential is the

equilibrium water content calculated from the polycondensation equilibrium and the end group concentration. If the melting is carried out at lower water contents, the equilibrium water content (Z. Faserforschung und Textiltechnik 23 [1972] p.325), did viscosity increases by more than 100% within minutes due to post-polycondensation; at a higher H ₂ O content occurs a hydrolytic Kettenspaltupg. In the automated manufacturing sector, therefore, is the

Maintaining a uniform melt viscosity when large moldings (shot volume> 300 g / part) are sprayed,

required.

Object of the invention

The aim of the invention is the ionic production of polyamide-6 molding compositions which are flame-retardant, self-extinguishing and stable to processing.

Explanation of the essence of the invention

The invention has for its object to improve the polyamide-6-Formroasse both in terms of flame retardance and self-extinguishing and preparation stability using only one additional component. This object is achieved by an additional component which is added in the melt as a stabilizer and flame retardant to a polyamide molding composition which optionally also contains glass fibers, pigments or other additives in an amount of 5 to 10% (mass) based on molding composition , wherein according to the invention, this component is Benzoesäuresulfimid.

Although benzoic acid sulfide is a combustible substance, it causes both a reduction in the combustibility of the polyamide-6 molding compound, as measured by UL-94 tests, and an increase in the oxygen index. The modified polyamide-6-Fornmasse retains the light inherent color and can therefore be colored to all color settings. The oxygen index represents a number that defines the oxygen concentration at which a test specimen is just like a kercenartig from top to bottom

burns down. According to J. Troitzsch, fire behavior of plastics, Carl Hauser Verlag Munich, Vienna, 1980, p.390, is the

Oxygen index test a good tool for material development and material testing, if materials with the same

chemical basis, z. As polyamides, are compared. The execution of the test is standardized. The values found prove the special advantages of the polyamide 6 molding composition of the invention.

The flammability test according to the UL-94 test, according to the test specifications of the "Underwriters Laboratories, Inc., USA"

has prevailed worldwide. The classifications according to this test prove the flame retardancy, preventing one

Fire spread by classification in the field of VO, d. H. no burning dripping when flaming or in the

Fire.

No previous scientific-technical solution has at the same time in addition to the improvement of fire behavior the Processing stability increased. The improvement in processing stability, i. constant Vi? C osity of the melt over

a longer period of time, requires according to Kunststoffhandbuch, Bd. Vl, Prof.Vieweg, Carl Hauser Verlag Munich, 1966, p.224, an exact compliance with the equilibrium water.

The viscosity of the polyamide-6 molding composition according to the invention remains constant over a lye period, too

who ι is working with very low levels of water in the molten product. These properties permit continuous production of large moldings and represent a major technological advance.

It is new and essential that both stabilization and flame retardancy are achieved by a single component

become.

embodiments In a twin-screw extruder with a temperature profile in heating zones 1,2,3,4 and 5 of 533K, 530K, 522K, 512K,

500 K, polyamide δ is melted with a relative solution viscosity of 2.4 to 2.8 and reacted with different proportions of Benioesulfimid and optionally other additives, such as glass fibers, pigments and fluxes.

As a comparative example, the polyamide 6 was used without the addition of benzoic sulfide, only with Zn-borate. The results are

shown in the following table. Examples 2, 3 and 4 are carried out without and with Zn-borate.

ingredients blow Zugfe Angry UI.94 enamel biegefe stigkeit material 2 mm viscometers stigkeit after TGL index wall ty nachTGL 14070 % thickness 25O ⁰ C ' 140068 N / mm ² P mJ / mm ² nachBMjn. 1. 97% polyamide 3% zinc borate br. n. 80 23 HB 1350 2. 92% polyamide 5% benzoic sulph imide 48 74 25 V2 RF70 + 3% zinc borate 42.5 75 26 V2 8EO 3. 39.5% polyamide 7.5% BeiUoe- sulfimide 42.8 73.6 26.5 V1 865 + 3% zinc borate 38.2 72.3 28 V1 855 4. 87% polyamide 10% benzoin sulfimide 38.7 71.8 30 VO 880 + 3% zinc borate 35.6 69.9 32 VO 850

Claims (1)

Stabilizer and flame retardant for polyamide molding compositions, which optionally also contain glass fibers, pigments or other additives, which is added to the polyamide in amounts of 5 to 10% (mass), based on molding composition, in the melt, characterized in that the stabilizer and Flame retardant Benzoesäuresulfiinid is. Field of application of the invention The invention relates to a stabilizer and flame retardants for the rational production of flame-retardant self-extinguishing polyamide S molding mass, which are stable to processing.