DE1769231A1 - Thermoplastic molding compounds made from polyesters and polyamides - Google Patents

Description

April 5, 1968 Dr.MD/T

Thermoplastic molding compounds made from polyesters and polyamides

It is known that linear saturated polyesters are more aromatic To process dicarboxylic acids by the injection molding method. Injection molding is of technical importance of polyethylene terephthalate. Injection molded parts made of polyethylene terephthalate show after they have been removed from the mold however, the disadvantageous property that infdfee

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Post-crystallization, especially at higher temperatures, their dimensional stability is not preserved. It has therefore been proposed several times to use polyethylene terephthalate to be mixed with nucleating inorganic substances. These polyester molding compounds are generally injected into heated molds.

The reduced specific viscosities of these polyester molding compounds are in the range of about 1.2 to 1.5 dl / g (measured on 1% solutions in phenol / tetrachloroethane 6o: 4o at 25 C). Polyethylene terephthalate with reduced specific viscosities the essential are above 1.5 dl / g, produce moldings during processing that have considerable warpage.

It has now been found that thermoplastic molding compositions obtained by mixing

(a) linear saturated polyesters of aromatic dicarboxylic acids and optionally small amounts of aliphatic Dicarboxylic acids with saturated aliphatic or cycloaliphatic diols and

(b) 0.5 to 50% by weight, preferably 5 to 3o% by weight, based on based on the weight of the thermoplastic molding compound, linear saturated polyamides

are produced in the melt, are ideally suited for injection molding.

The molding compositions according to the invention - hereinafter referred to as polyester amides - can surprisingly also without the use of an inorganic nucleating agent to crystalline moldings with excellent prostitution

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sion stability can be processed. It was still Surprisingly, that molding compounds whose reduced specific viscosity considerably exceeds 1.5 dl / g, can be processed into distortion-free, dimensionally stable moldings. Those made from these molding compounds Moldings show remarkably good demoldability even without using a wax as well as good impact strength.

The polyester molding compounds are produced by intensive mixing of polyesters and polyamides in the Melt. The mixing times can be 1/2 minute to 15 minutes, preferably 1 to 5 minutes. To the Mixing 'the polyester with the polyamide, an extruder is expediently used.

Polyethylene terephthalate is preferably used as the linear saturated polyester of aromatic dicarboxylic acids. It is also possible to use other polyesters, for example polycyclohexane 1,4-dimethylol terephthalate, ^ Modified polyethylene terephthalates can also be used use which, in addition to terephthalic acid, also contain other aromatic or aliphatic dicarboxylic acids as basic units, e.g. isophthalic acid, naphthalenedicarboxylic acid-2,6 or adipic acid. Can also be modified Polyethylene terephthalates are used which, in addition to ethylene glycol, also contain other aliphatic diols, such as for example neopentyl glycol or 1,4-butanediol as contain alcoholic components. Mixtures of polyesters can also be used.

The polyesters used to produce the polyester amides should expediently have a reduced specific viscosity dl / g (measured on a 1% solution in phenol / tetrachloroethane 6o; 4o at 25 ° C) between o, 6 and 2, o,

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preferably between 1.0 and 1.6.

The usual linear polyamides are used as polyamides, such as, for example, polycaprolactam (6-polyamide), poly-hexamethylene adipamide (6,6-polyamide), poly- (^ jU) -undecanamide (11-polyamide) or poly-O ^ W-dodecane amide (12-polyamide). It is also within the meaning of the invention to use mixtures of polyamides.

The polyamides should expediently have a reduced specific viscosity dl / g (measured on a 1% solution in phenol / tetrachloroethane 6o: 4o at 25 ° cJ) between o, 6 and 6, o, preferably between 1 and 3, ο have.

The polyester amides according to the invention are said to be useful a reduced specific viscosity dl / g (measured on a 1% solution in phenol-tetrachloroethane 6o: 4o at 25 C) between 0.8 and 4.0, preferably between 1.0 and 2.5. They can be prepared as described above Polyester amides, post-condense in the solid phase by known processes.

Pigments such as titanium dioxide or carbon black can be added to the polyester amides. If a very rapid crystallization is important in order to be able to work particularly short mold standing times, the known inorganic nucleating agents can also be added to the molding compound. Inert inorganic solids with a grain size of less than 5 yu, preferably less than 2 yu, are suitable as such, for example calcium carbonates, calcium sulfate, aluminum silicate or talc. The pigments or nucleating agents can be added at various points in the manufacturing process for the molding compounds. For example, these substances can be used in the production of the starting polyester during the polycondensation

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sation- admit. One can use the pigments or nucleating agents also mix with the polyester together with the polyamide. Furthermore, the granulated molding composition can be mixed with the pigment or nucleating agent in a rotating Treat vessel.

The polyester amides should contain as little moisture as possible, preferably less than 0.02% by weight. Man can the granulated polyester amides, with a coating made of an inert hydrophobic material such as wax or paraffin.

In order to obtain moldings with a sufficient degree of crystallization when processing the polyesteramides, it is expedient to keep the mold temperature sufficiently high above the glass transition temperature of the polyester component of the polyesteramide used. If the polyester component of the polyesteramide consists of polyethylene terephthalate, the temperature should
will be.

The temperature of the injection mold is kept at around 12o to 16o C

The polyester anixdf shapes according to the invention allow the production of high-quality moldings such as program disks, clutch disks, gear wheels, water fittings i.a.

Example 1: ■

54oo g of polyethylene terephthalate powder with a reduced specific viscosity of 1.59 dl / g (measured on a 1% solution in phenol / tetrachloroethane 6o: 4o at 25 ° C) were with 600 g of polycaprolactam powder with a reduced specific viscosity of 1.18 dl / g (ge

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measure on a 1% solution in phenol / tetrachloroethane 6o ': 4o at 25 C) intensively mixed in a rotating vessel with exclusion of moisture, in one Vertical extruder melted, homogenized and granulated. The granules were in a tumble dryer 2 Hours at 100 ° C and a pressure of 0.4 mmHg and then Dried for 1 hour at 18o C and a pressure of 0.4 mmHg. The granules that have a reduced specific viscosity of 1.58 dl / g was rolled with 0.4% by weight of polyethylene wax at 18o under nitrogen at normal pressure.

The material was made into plates measuring 6o χ 6o χ 2 mm injected at a mold temperature of 15o C. The plates, which were dimensionally stable, had a mold life a density of 1.336 for Io seconds; the density of the panels increased only insignificantly with longer mold standing times at.

Example 2:

The procedure was as in Example 1, with the difference that instead of polycaprolactam a poly (hexamethylene adipamide) with a reduced specific viscosity of 1.72 dl / g (measured on a 1% solution in phenol / Tetrachloroethane 6o: 4o at 25 ° C) was used. After granulating and drying, the polyesteramide was found a reduced specific viscosity of 1.63 dl / g. That Granules were treated as in Example 1 with polyethylene wax. The ones made from your material at a mold temperature Plates with good dimensional stability (6o χ 6o.x 2 mm) injected at 15 ° C. had a mold standing time of 5 seconds a density of 1.344, which no longer increased even with longer mold service lives.

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In a comparative test 54oo g of polyethylene terephthalate powder (reduced specific viscosity 1.59 dl / g) 600 g of poly (hexamethylene adipamide) "(reduced specific viscosity 1.72 dl / g) and 18 g of aluminum silicate powder (47 % SiO _n ; 38 % Al ₀ O ₀ ; 75 % below 2 μ

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Particle size) mixed / further processed as described above. The panels molded from this material had a density of 1.344. By using a inorganic nucleating agent could therefore not "increase the degree of crystallization of the plates obtained will.

Example 3:

48oo g of polyethylene terephthalate powder with a reduced specific viscosity of 1.59 dl / g (measured on a 1% solution in phenol / tetrachloroethane 6o V 4o at 25 ° C) were with 1200 g of poly (hexamethylene adiparaid) with a reduced specific viscosity of 1.72 dl / g (measured on a 1% solution in phenol / tetrachloroethane 6o: 4o at 25 C) mixed intensively and processed as in Example 1. The dried granules (reduced specific viscosity 1.72 dl / g) was treated with polyethylene wax as in Example 1 and made into plates (6o χ 6o χ 2 mm) processed (mold temperature 15o ° C). The panels made from this material had at a mold standing time of 5 seconds a density of 1.318, which increased only slightly with longer mold standing times.

Example 4:

54oo g of polyethylene terephthalate powder with a reducing agent 209810/1449

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th specific viscosity of 1.64 dl / g (measured on a 1% solution in phenol / tetrachloroethane 6o: 4o at 25 C) were with 600 g of poly-cC, W-undecanamide with a reduced specific viscosity of 1.1 dl / g (measured on a 1% solution in phenol / Tetrachloroethane 6o: 4o at 25 C) in a rotating Vessel intensively mixed with exclusion of moisture, melted in a vertical extruder, homogenized and granulated. The granules were placed in a tumble dryer Dried for 2 hours at 100 ° C. and a pressure of 0.3 mmHg. Then the product was in a tumble dryer for 8 hours 24o C and a pressure of 0.3 mmHg in the solid phase. The material was not treated with wax.

Dimensionally stable plates (6o χ 6o χ 2 mm) were injected from the granulate (reduced specific viscosity I _{5 8 dl / g) at a mold temperature of 150 ° C.} With a mold standing time of 15 seconds, the plates had a density of 1.317, which increased slightly with longer mold standing times. The good demoldability of the panels was remarkable.

The impact strength of the panels was tested by means of a drop test. Here, the test plates were a Exposed to impact stress in such a way that a falling body sliding on low-friction shafts can be found in various Heights dropped vertically onto the panels stretched out on a frame. The drop hammer's syringe turned off represents a hemisphere with the radius Io mm, the weight was 1 kg. 90% 'of the panels were also at a height of fall of 225 cm not broken.

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Claims (1)

Fw 57ol on April 5, 1968 P at en t a η s ρ r u c h: Thermoplastic molding compounds for injection molding, characterized in that it is obtained by mixing (a) linear saturated polyesters of aromatic dicarboxylic acids and optionally small amounts of aliphatic dicarboxylic acids with saturated aliphatic ones or cycloaliphatic diols with (b) 0.5 to 50% by weight, based on the total weight the molding compound, linear saturated polyamides be produced in the melt. 2OSS.1-07 U41 ORiGiNALlNSPEeTED