DE2454002A1 - THERMOPLASTIC POLYBUTYLENE TEREPHTHALATE MOLDING COMPOUNDS WITH INCREASED TOUGHNESS - Google Patents

Description

Our reference: O.Z. 30 974 Ka / lSun 6700 Ludwigshafen, November 13th, 1974

The invention relates to thermoplastic polybutylene terephthalate molding compositions with increased impact strength, especially at low temperatures.

However, moldings of polybutylene terephthalate have not only excellent for many applications mechanical properties, high surface hardness and good gloss "For a number of applications, the impact resistance at room temperature and especially because of the relatively high glass transition temperatures of 75 ° C or 6O ⁰ C below 20 ⁰ C insufficient. It is therefore desirable for many areas of application to have higher-impact polybutylene terephthalate form materials available both at room temperature and at low temperatures. In doing so, however, the other mechanical properties, such as rigidity, should not be impaired or should only be impaired to an acceptable extent.

The invention relates to thermoplastic molding compositions of high impact strength which are characterized in that they exist the end

A) 100 parts by weight of a polybutylene terephthalate with a relative viscosity of 1.3 to 2.0, measured in a phenol / o-dichlorobenzene mixture at 25 ^° C. and

B) 0.5 to 35 parts by weight of a graft polymer of ύ (-olefin-vinyl ester copolymers and 0.5 to 10 percent by weight, based on the copolymer polymerizable unsaturated carboxylic acids or polymerizable unsaturated Carboxylic acid esters and / or

0.5 to 35 parts by weight of a graft polymer from oC-olefin-acrylic acid ester copolymers and

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0.5 to 10 percent by weight, based on the copolymer, polymerizable unsaturated carboxylic acids or polymerizable unsaturated carboxylic acid esters as well

C) optionally 10 to 8Ό parts by weight of fillers as well as other additives, if applicable.

The fact that special graft polymers are the polybutylene molding compounds impart outstanding advantageous properties is surprising to the person skilled in the art and was in no way foreseeable.

That used for the production of the molding compositions according to the invention Polybutylene terephthalate as component A usually has a relative viscosity of 1.5 to 1.8, preferably 1.5 to 1.7. the relative viscosity was in 0.5 $ solution at 25 ° C in one Phenol / o-dichlorobenzene mixture (3; 2 parts by weight) determined. the thermoplastic polybutylene terephthalate molding compositions contain polybutylene terephthalate, which is up to 20 mol percent with other dicarboxylic acids or alcohols may be modified, as modifiers for example, aliphatic, cycloaliphatic or aromatic dicarboxylic acids, sebacic acid, dodecanedioic acid, Cyclohexanedlcarboxylic acid, isophthalic acid or naphthalenedicarboxylic acid in question, alcoholic modifying components can, in particular, be aliphatic or cycloaliphatic glycols with 2 to 10 carbon atoms, such as ethylene glycol, propylene glycol, Pentamethylene glycol, hexamethylene glycol, neopentyl glycol and diethylene glycol.

An essential feature of the new molding compositions is their content of component B, a graft polymer made from of-olefin-vinyl ester copolymers and polymerizable unsaturated carboxylic acids or polymerizable unsaturated carboxylic acid esters and / or of a graft polymer from q <-olefin-acrylic acid ester copolymers and polymerizable unsaturated carboxylic acids or polymerizable unsaturated carboxylic acid esters. o <-olefins in the context of the invention are in particular ethylene and propene (T).

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Particularly suitable vinyl esters are vinyl acetate and vinyl propionate, alone or in combination with one another. As carboxylic acids Acrylic acid is particularly suitable for the purposes of the invention and methacrylic acid. Acrylic acid esters are, in particular, esters of acrylic acid and methacrylic acid with alcohols 1 to 18 carbon atoms are used. The preparation of the graft polymers used according to the invention is described below and in Examples a and b illustrated;

Homogeneous graft polymers without homopolymer formation from Ck .'-olefin-vinyl ester copolymers or O ( -olefin-acrylic ester copolymers with polymerizable, unsaturated carboxylic acids or polymerizable unsaturated carboxylic acid esters are obtained, for example, if moldings made from ethylene-vinyl ester copolymers are obtained, for example. B. Granulate at room temperature in a mixer with liquid, polymerizable, unsaturated carboxylic acids or their esters containing free radical initiators in dissolved form, until the carboxylic acid is homogeneously distributed in the moldings by diffusion an extruder, extruders and screws are used which bring in less than 50% of the required heat by shear heat.The necessary free radical initiators are in amounts of 0.002 to 0.5 percent by weight, based on the copolymer, in the monomeric acids or esters solved and on applied the molded body. Free-radical initiators are all common peroxides, such as dibenzoyl peroxide, dicumyl peroxide and di-tert-butyl peroxide and azo compounds.

To produce the graft polymers, for example, molded articles made from copolymers, e.g. B. granules, as in the Production of the copolymers is obtained by packaging, at room temperature with the carboxylic acids or esters and see the radical! initiators mixed and after a dwell time heated in an extruder from 2 to 10 hours. The residence time after mixing depends on the amount of comonomers in the copolymer and according to the amount of carboxylic acid or ester. With a high proportion of comonora and with low amounts of carbonic acid

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the residence time can be low. The residence time should ensure a homogeneous distribution of carboxylic acid and / or carboxylic acid ester and allow initiator in the polymer ;, It is essential for the appearance of the graft polymer. Will the mix in one Melted extruder under mild mechanical conditions, the carboxylic acid is grafted onto the copolymer. Included It is important that as little shear as possible is introduced into the polymer by the screw. The required heat should predominantly be introduced by external heating. Screws of the same flight depth, so-called conveyor screws, have proven to be favorable Screws, as proven for rubber compounds or those with low core progression. The speed of the screw is expediently chosen as small as possible.

Reinforcing fillers in the sense of component C are those which increase the rigidity of the polyester is increased. Fibrous substances are preferred, in particular Glass fibers made of low-alkali Ε-glass with a fiber diameter between 8 and 14 / U and a glass fiber length in the injection molded part between 0.01 mm and 0.5 mm. The glass fibers can be as continuous fibers or as cut or ground glass fibers are used, the fibers with a suitable sizing system and an adhesion promoter or adhesion promoter system can be equipped on a silane basis.

However, other fibrous reinforcing materials such as carbon fibers, K-titanate single crystal fibers, gypsum fibers, Alumina fibers or asbestos are incorporated. Non-fibrous Fillers such as B. glass spheres, hollow glass spheres or chalk, quartz, natural and calcined kaolins are also preferred as combinations of these materials with glass fibers. These fillers can, like the glass fibers, also with a Sizing and / or an adhesion promoter or adhesion promoter system be provided.

The production of the thermoplastic polybutylene terephthalate molding compositions according to the invention takes place according to the usual processes for melt processing, such as those used in plastics

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Handbuch, Volume VII, Polyamide, Munich, 1966, are described.

The polybutylene terephthalate molding compositions according to the invention can still flame retardant additives z. B. on the basis of elementary red phosphorus, phosphorus compounds, halogen, antimony and nitrogen compounds, furthermore dyes and color pigments, Stabilizers against thermal, thermo-oxidative and UV damage, waxes, lubricants and processing aids, the ensure trouble-free extrusion and injection molding and contain antistatic agents.

Principle of the production of the graft polymers (component B)

Example a: Example b:

100 parts contains dissolved a copolymer in granular form from 88 parts with 12 parts ethylene vinyl acetate with a melt index (19O ⁰ C, 2.16 kg) of 6 and 3 parts of acrylic acid, 0.03 part of dibenzoyl peroxide, are mixed for 10 minutes. After a residence time of 4 hours, the mixture is melted in an extruder with a screw of the same flight depth and a screw length of 27 D at a speed of 12 rpm and a temperature of 140 ° C. is maintained. A shear heat of less than 30 f was determined from the energy absorption. A product with an acid number of 32 is obtained.

Dissolved 100 parts of a copolymer in granular form of 80 parts ethylene and 20 parts of n-butyl acrylate having a melt index (19O ⁰ C, 2.16 kg) of 18, a softening point of 102 ⁰ C and 4 parts acrylic acid 0.04 part of dibenzoyl peroxide are mixed for 15 minutes. After a residence time of 2 hours, the doped pellets is heated with exclusion of air in a tube at 8O ⁰ C and held for 5 hours at this temperature. A product with an acid number of 30.9 is obtained.

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Production of thermoplastic polybutylene terephthalate molding compounds

Examples 1 to 3

2,000 g of a polybutylene terephthalate with a relative viscosity of 1.655 and 222 g of a graft polymer B were intimately mixed in a fluid mixer at room temperature. Subsequently, the mixture was melted in a heated to 25O ⁰ C twin-screw extruder (type ZDSK 28 of the Fa. Werner and Pfleiderer, Stuttgart). The extruded mixture was granulated, dried and processed mm on an injection molding machine at an injection temperature of 24O ⁰ C. to give standard small bars with dimensions of 4 χ β χ 50th The test specimens were provided with a J5 mm hole in the middle. Subsequently, the notched impact strength was determined in as described in "Kunststoffe" 57 (I967), pp 825-828 + 23 ⁰ C and - 30 ⁰ C determined.

Comparative example

2000 g of a polybutylene terephthalate having a relative viscosity of 1.655 (28 Fa. Werner & Pfleiderer, Stuttgart type ZDSK) were melted in a heated at 250 ⁰ C twin-screw extruder. The procedure described in Examples 1 to 3 was then followed.

The results are shown in Table 1.

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co example Table 1 Graft component colour Hole impact resistant ■ ■ O Graft polymer B (Weight #) of speed (KJ / m ² ) CD _ Spray +23 ⁰ C -3O ⁰ C OO Copolymer lings ΓΟ Comparison
example 1 White 37.5 26.7 ro 4 acrylic acid O co
O 1 White 54.1 45.4 Ethylene vinyl acetate 3O methacrylic (33 wt. ^) acid methyl 2 ester White 47.5 36.6 Ethylene vinyl 4 acrylic acid acetate ■, 3 (33 wt. ^) White 40.0 34.2 Ethylene acrylic acid-n-butyl- ester (15 wt. ^)

OO I

VD

Ni

Claims (1)

- 8 - ο.ζ. 30 97 ^ Claim Thermoplastic polybutylene terephthalate porous masses with high toughness, characterized in that they consist of A) 100 parts by weight of a polybutylene terephthalate
with a relative viscosity of 1.3 to 2.0,
measured in a phenol / o-dichlorobenzene mixture
at 25 ° C and B) 0.5 to 35 parts by weight of a graft polymer composed of o * -olefin-vinyl ester copolymers and 0.5 to 10 percent by weight, based on the copolymer, polymerizable unsaturated carboxylic acids or polymerizable unsaturated carboxylic acid esters and or 0.5 to 35 parts by weight of a graft polymer of oC-olefin-acrylic acid ester copolymers and
0.5 to 10 percent by weight, based on the copolymer, polymerizable unsaturated carboxylic acids or unsaturated carboxylic acid esters
as C) optionally 10 to 80 parts by weight of fillers
and, if necessary, other additives. BASF Aktiengesellschaft 609822/0807