JPS61197656A - Forming material based on polyamide having reduced properties - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to molding compositions based on polyamides which have reduced properties and therefore have important advantages with respect to their handling during production and processing.

Conventional technology polymers are above the glass transition point! It is known that "r!" has a rather pronounced tendency in the properties. It describes the properties of the particles of the molding material, in particular the tendency of the granules or powders to stick to each other. This property increases with increasing temperature. ,
If not stopped by suitable measures, it will proceed until nodules are formed.

This property is directly related to the softening properties of the polymer.

As the polymer softens, it will become sticky (t#)
Adhesion increases with increasing temperature. Therefore, the greater the difference between the glass transition temperature and the respective production temperature, the more pronounced this property and thus, for example, the tendency to agglomerate the granules or powder.

Furthermore, the extent of this property is significantly influenced by the crystallinity of the polymer. In an amorphous polymer, tackiness can be observed at a temperature already above the glass transition point (1), but the corresponding temperature is clearly higher than this in a crystalline polymer. Polymers with a very high degree of crystallinity are only observed at the beginning of the melting range.

During the production and processing of polymeric molding materials, it is often advantageous, and sometimes even unavoidable, to treat the molding materials to temperatures above their glass transition temperature. Particle agglomeration or agglomeration has an adverse effect on processing; for example, the drying of polymers often takes steps below the glass transition temperature to achieve an economically acceptable drying time and the required moisture content. For molding materials whose glass transition temperature is in the range of room temperature or below, countries with particularly hot climates (here) may be exposed to temperatures above 40 °C. Undesirable agglomeration can occur during storage (as is normally the case).

In order to reduce this property, and with it the tendency towards nodule formation and the resulting difficulties in processing the molding materials, various measures are known.

First, in the case of crystallizable molding materials, for example, the already mentioned fact is utilized, namely that the properties decrease as the degree of crystallinity increases. The crystallinity of the molding material is increased by heat treatment, in which case it is operated according to a specific temperature program, so that the temperature is increased in a time-dependent manner to such an extent that it allows the properties to decrease with increasing crystallinity. For Copolymer 1, this heat treatment takes a very long time.

This is because the copolymers have a distinctly lower crystallization rate than the corresponding homopolymers as well as a lower maximum achievable crystallinity, and the temperature during the heat treatment can be adjusted very slowly without agglomeration. There is only an increase of 1, so there is f.

Another means of reducing this property is to add substances to the molding compound that act as separating agents. For this purpose, the molding material present in the form of granules, powder, etc. is superficially sprinkled with a separating agent in a separate working step. However, this separating agent has the disadvantage that it loses its effect when the molding material is melted and the separating agent is mixed into the molding material. If the separating agent is not homogeneously miscible with the polymeric molding material, the molding material may be affected in an undesirable manner.

here! The properties and related matters described for polymeric molding compositions in general also apply in particular to polyamide-based molding compositions.

The object of the invention was to reduce, by suitable measures, the properties of polyamide-based molding compositions without the disadvantages mentioned above.

The molding composition based on polyamide according to the invention, the properties of which are significantly reduced, has a
It is characterized in that 5 to 5% by weight of a hydrophilic silicone compound is added.

Polyamides according to the invention include all homopolyamides and copolymers which can be prepared by known methods from aminocarzenic acids or, to the extent possible, the corresponding lactams and/or diaminocarzenic acids or their salts. Polyamides may be mentioned.The molding materials according to the invention may contain additives such as stabilizers, plasticizers, pigments, fluorescent brighteners, reinforcing agents and fillers.

As hydrophilic silicone compounds according to the invention, in particular silicone surfactants are used. This is primarily a silicone polyalkylene oxide copolymer, in which case a distinction is made in principle between hydrolyzable silicone surfactants (according to formula 1) and non-hydrolyzable silicone surfactants (according to formula 2). However, R represents an alkyl group, and R/ represents an alkyl group. Polyalkylene oxide group -(CnH2
nO)z- may be composed of polyethylene oxide or a block polymer composed of a polyethylene oxide block and a polypropyleneoxy P block.

Products of this type are available on the market, and representative examples include, among others, Silwet L-720O! Bi L-75
00, Baysl Ion 0F1
0H-OR603 as well as silicone oil LO50 from Watzker Hiemi GmbH, Munich.

The addition of hydrophilic silicone compounds to polyamides
This can be done during or after its manufacture. The silicone compound can therefore be mixed with the polyamide in the melt state before, during or after the polymerization, or else in solid form, especially in the form of granules or powder! It is also possible to spray the existing polyamide superficially.

The hydrophilic silicone compound is 0, OO with respect to the polymer.
It is added in an amount between 5 and 5% by weight, in particular between 0.05 and 2% by weight. The optimum amount in this case depends on the type of addition.

When the hydrophilic silicone compound is mixed into the polyamide in a molten state, a t'''1%'1% of 0.5 to 2% by weight is best obtained, and when it is superficially sprinkled onto the solid polyamide, a t''. Amounts of 0.05 to 0.5% by weight are advantageous.

Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 In a stirring autoclave, 40 parts by weight of laurin lactam, 60 parts by weight of caprolactam, 2 parts of water, and 290°C for 5 hours after closing.
Heat to ℃. The pressure is kept at a maximum of 20 par with possible relief. Thereafter, within one hour, the pressure is reduced to atmospheric pressure by venting the autoclave, and at the same time the temperature of the reaction mixture is reduced to 260.degree. Silicone surfactant Silwet L-75000 from Union Carnoy P Co., Ltd.
．． 8 parts by weight are added and the polymerization is continued by passing in nitrogen. After 8 hours, the desired degree of polymerization was obtained, corresponding to a solution viscosity of 1.83 (measured as a 0.5% solution in m-cresol at 20 DEG C.).

The polymer is removed from the autoclave in strand form, solidified by passing through a water bath, and granulated. The granules are fed into a silo where they are stored for 24 hours. The temperature of the granules is reduced from an initial 35°C to 30°C during storage. The granules are then introduced into a rocking dryer whose heating medium has been cooled to room temperature. No difficulties arise in this case due to agglomeration of the granules. 20) After applying a vacuum, heat the rocking dryer. After about 1 hour the heating medium reached a temperature of 90° C. and after about 2 hours the product was warm. When the granules are removed from the oscillating dryer after drying, no granule agglomeration or adhesion to the wall of the dryer can be observed.

Example LA (Comparative Example) Polyamide granules according to Example 1 are prepared without addition of silicone compounds. The granules are fed into a silo as in Example 1, but in order to avoid agglomeration, approximately 15
Must be cooled through air at ℃. After storage for 24 hours, the granules are placed in a rocking dryer and dried as in Example 1. In order to avoid sticking between granules or to the peripheral wall of the dryer, the temperature of the heating medium is adjusted in stages to
℃, 65°C after 1 hour, and 85°C after another hour. In order to obtain the required moisture content of the granules of 0.02% H2O, an additional drying time of 8 hours is required.

A comparison of the descriptions in Example 1 and Example IA shows that due to the addition of the silicone compound according to the invention and due to the reduced nature of the resulting polyamide, in particular, it has not yet been heat treated.
It also clearly shows that a problem-free storage of crystallized granules as well as a fast and efficient method of operation in drying these granules is possible.

Example 2 In a stirred autoclave, 40 parts by weight of caprolactam,
20 parts by weight of AH salt, 16 parts by weight of hexamethylene diamine, 14 parts by weight of azelaic acid, 15 parts by weight of dodecanedioic acid and 3 parts by weight of water were added, and after exchanging air, the mixture was heated to 260° C. for 1 hour. In this case, the pressure in the autoclave is reduced to atmospheric pressure and the polymerization is continued by passing in nitrogen until a degree of polymerization corresponding to a solution viscosity of 1.55 is reached. The polymer is removed from the autoclave, granulated and dried as described in Example 1.

100 parts by weight of the granules thus obtained were mixed with 1 part by weight of silicone oil LO500 from Warakah Hiemi,
This is then simultaneously ground in a pin mill while cooling with liquid nitrogen. From the crushed material, a fraction having a particle size of 80 to 200 μm was sieved, and 0.1% of magnesium stearate was extracted. -Jt
Mix with %. A sample of the powder thus obtained was
-r! Store for 3 days and subsequently determine nodule formation. The results are listed in Table 1.

Example 2A (Comparative Example) It is carried out as in Example 2, but no hydrophilic silicone compound is added to the granules before milling.

Table 1 1 Judgment of nodule formation 0 = No nodule formation 1 = Mild nodule formation, nodule is easily crushed by hand 2 =
Moderate nodule formation, nodules are crushed only with strong hand pressure

Claims (1)

[Claims] 1. A polyamide-based molding material with significantly reduced properties, characterized in that it contains a hydrophilic silicone compound. 2 The hydrophilic silicone compound is 0.0% relative to the polyamide.
Molding material according to claim 1, added in an amount of 0.005 to 5% by weight. 3. The molding material according to claim 1, wherein the hydrophilic silicone compound is mixed with the polyamide by adding it before, during or after polymerization. 4. Claim 1, wherein the hydrophilic silicone compound is dispersed on the polyamide present in the form of granules or powder.
Molding materials listed in section. 5. The molding material according to claim 1, wherein a silicone surfactant is used as the hydrophilic silicone compound.