NL7903369A - Thermoplastic polyester with improved dimensional stability - comprises polybutylene terephthalate, and clay, metasilicate, polyester, polycarbonate and novaculite-modifier - Google Patents

Abstract

A thermoplastic compsn (I) comprises (a) a mixt. of poly-(1,4-butylene terephthalate) (PBT) and poly(ethylene terephthalate) and (b) =60 pts. wt. of a modifier per 100 pts (I). The modifier comprises >=1 of (i) (amino)silane-treated clay, (ii) acicular Ca metasilicate, (iii) segmented copolyester and aromatic polycarbonate and (iv)novaculite. Also claimed is a compsn. comprising PBT and modifier of aminosilane-treated clay and a segmented copolyester. Compsns. (I) are useful for moulding e.g. injection compression and transfer and have low warp after moulding and excellent impact strength.

Description

5, *, 1 * 1 S 2348-945 Ned.

#

General Electric Company of Schenectady, New York, USA.

Modified, polyester-containing composition.

The invention relates to modified, thermoplastic, polyester-containing compositions that are more easily moldable into articles with improved dimensional stability.

More particularly, the invention relates to compositions containing a poly (1,4-butylene terephthalate) resin and optionally a poly (ethylene terephthalate) resin and modified with an effective amount of a mineral filler or a combination of resins.

Linear polyesters and copolyesters of glycols and terephthalic acid or isophthalic acid have been available for a number of years. These materials are described, inter alia, in U.S. Patents 2,465,319 and 3,047,539. These patents disclose that the polyesters are particularly advantageous as film and fiber-forming materials.

With the development of molecular weight control and the use of nucleating agents and two-step molding operations, poly (ethylene terephthalate) has become an important constituent of injection moldable compositions. Due to its very fast crystallization from the melt, poly (1,4-butylene terephthalate) is particularly suitable as a constituent in these compositions. Workpieces formed from these polyester resins have a high degree of hardness and abrasion resistance, a strong gloss and a low surface friction, compared to other thermoplastic materials.

Stable mixtures of poly (1,4-butylene terephthalate) and poly (ethylene terephthalate) with or without reinforcing agent can be formed into useful articles, see U.S. Patent 3,953,394.

It has now been found that the processability and dimensional stability of these polyesters and blends of polyesters can be greatly improved by intimately mixing these materials with certain modifiers.

In one aspect, the invention provides thermoplastic compositions suitable for molding operations, for example, injection molding, compression molding, compression molding, and the like. The present compositions contain: a) an intimate blend of a poly (1,4-butylene terephthalate) resin and a 7903369 <I>.

2 poly (ethylene terephthalate) resin; and * b) a modifier for this in an amount of up to 60 parts by weight per 100 parts by weight. din (a) and (b), namely (i) a silane-treated clay; (ii) acicular calcium metasilicate; (iii) a combination of a segmented copolyester and an aromatic polycarbonate; or (iv) novaculite; or a mixture of 2 or more of these materials.

In a second aspect, the invention provides thermoplastic compositions containing a) a poly (1,4-butylene terephthalate), and b) a modifier therefor, namely a combination of an aminosilane-treated clay and a segmented copolyester.

The polyester resins of the compositions of the invention are commercially available or can be prepared by known methods, for example, by alcoholysis of esters of terephthalic acid 15 with ethylene glycol or butanediol and subsequent polymerization, by heating glycols with the free acids or with halide derivatives thereof, and similar methods. These methods are described, inter alia, in U.S. Patents 2,465,319 and 3,047,539.

These high molecular weight polyesters have, for example, an intrinsic viscosity of at least about 0.4 dl / g and preferably ...............

of at least 0.6 dl / g, determined at 30 ° C in a mixture of phenol and tetrachloroethane (60:40).

When high melt strength is important, especially branched poly (1,4-butylene terephthalate) resins with high melt viscosity are suitable, which resins, a small amount, for example up to 5 mol% (based on the terephthalate units) , of a branching component with at least 3 ester-forming groups.

The branching component may provide branching in the acid units or in the glycol units of the polyester or it may be a hybrid.

Examples of these branching components are tri- and tetracarboxylic acids, such as trimesinic acid, pyromellitic acid and lower alkyl esters thereof, and the like, or (preferably) polyols and especially preferably tetrols such as pentaerythritol; triplets such as trimethylol propane; or dihydroxycarboxylic acids and hydroxydicarboxylic acids and derivatives thereof, such as dimethyl hydroxy terephthalate and the like.

The branched poly (1,4-butylene terephthalate resins and their preparation are described in U.S. Patent 3,953,404.

7903369 * »* 3

In certain preferred aspects, the composition contains reinforcing glass fibers. The glass fiber material to be used as reinforcement in these embodiments of the present compositions is known and can be obtained from a number of manufacturers. For compositions that are ultimately used for electrical purposes, it is preferable to use fibrous glass filaments consisting of calcium aluminum borosilicate glass which is relatively free of sodium.

This material is known as "E" glass. However, other types of glass are also suitable when the electrical properties are not so important, eg the low sodium glass known as "C" glass. The threads are manufactured according to standard methods, for example by steam or air blowing, flame blowing and mechanical stretching. The preferred wires for reinforcing plastics are made by mechanical stretching. The diameter of the wires ranges from about 9 to about 19 microns, but this is not critical to the invention.

Also, the length of the glass filaments is not critical, nor is it critical whether or not the filaments are bundled into fibers and these fibers are in turn woven into yarns, cords or slivers, or mats and the like. In the preparation of the present mold materials, however, it is convenient to use the fibrous glass in the form of chopped strands about 3.2 to 51 mm in length.

In contrast, even shorter pieces occur in articles formed from these materials, since significant breakage occurs during assembly. However, this is desirable since the best properties are exhibited by thermoplastic injection molded articles in which the length of the fibers is between about 13 microns and about 6.4 mm.

The amount of reinforcing glass can vary within wide limits, depending on the composition and the requirements imposed on the composition in question; it is only essential that an amount that is at least sufficient to provide reinforcement is used. Preferably, however, the amount of glass fibers serving as reinforcement material is 1-60% by weight of the total of glass fibers, (a) and (b).

It has also been found that the polyester materials of the invention, which contain modifiers and inorganic fillers, for example, talc, clay, and the like, and glass fibers, exhibit improved impact properties and flexural properties when the glass is dispersed in the resin.

It was further found that even a relatively small amount of the modifier (b) provides a significant improvement in processability, etc. Generally, however, the modifier (b) is present in an amount of at least about 1% by weight and preferably about 2.5-50% by weight of the total of (a) and (b). At amounts greater than 50% by weight, some degradation may occur in the ease of processing the material.

Modifier (b) (i), a silane-treated clay, can be obtained by treating finely divided reinforcing clay, for example, kaolin clay, a hydrophilic hydrous aluminum silicate, with a silane, for example, vinyl tris-2-methoxyethoxysilane to obtain a silane-treated, easily dispersible clay. A preferred silane-treated clay is obtained by reacting kaolin with Ϋ-aminopropylethoxysilane to yield an aminosilane-treated clay.

Modifier (b) (ii), acicular calcium metasilicate, also referred to as wollastonite, is commercially available as a filler for polyesters, melamine resins, epoxy resins, urethane resins, polyamides, and vinyl resins. The effectiveness can be improved by using silanes, as mentioned above for clay.

Modifier (b) (iii) is a combination of a segmented block polyester, for example a block-polybutene-polypropylene-glycol terephthalate resin, in combination with an aromatic polycarbonate, for example a resinous reaction product of bisphenol-A and phosgene.

These materials can be prepared by known methods and are commercially available, for example the former material as "Hytrel 4055" (a product of DuPont Company) and the latter material as "Lexan" (a product of General Electric Company). The relative amounts of the constituents of modifier (b) (iii) may vary within wide limits, for example, 1-99 parts by weight of the former component and 99-1 parts by weight of the second component, but generally contain 100 parts by weight. parts (b) (iii) 60-40 parts by weight of segmented copolyester and 40-60 parts by weight of aromatic polycarbonate.

Novaculite is a known commercially available crystalline micro-form of silicon oxide. The use of this material as a filler for polyesters is disclosed in the United States Patent Nos. 3,740,371 and 4,018,738. A preferred commercially available form of novaculite is a treated type manufactured by Malvern Minerals Co. is supplied under the name "Novakup 174-.05".

Furthermore, other ingredients such as dyes, pigments, flame retardants, dripping dripping agents, and the like may be added.

The compositions of the invention can be prepared by a number of methods. According to one of these methods, the modifying agent and optional reinforcing material (eg glass fibers) are combined with the resin components in an extruder mixer to obtain molding granules. The modifier and reinforcement material (if used) are dispersed in a matrix of the resin. According to another method, the modifier is dry-mixed with the resins, after which the mixture is flowed on a roller and crushed or extruded and chopped. The modifier can also be mixed with the resins and the mixture directly formed, for example, by injection molding or press injection molding.

It is always important to free as much as possible of all components (the resin, the modifying agent, the reinforcing material (if used) and any customary additives used.

Furthermore, the assembly should be carried out such that the residence time in the machine is short, the temperature is carefully controlled, the frictional heat is utilized and an intimate mixture of the resin and the modifier is obtained.

Although this is not essential, the best results are obtained if the ingredients are pre-formulated, granulated and then shaped. The pre-assembly can be performed in conventional equipment. For example, after careful pre-drying of the polyester resin, modifier and reinforcing agent (if used), for example, for 12 hours at 100 ° C under reduced pressure, a dry mixture of the ingredients can be used in a single screw extruder which screw has a long transition portion to ensure proper melting. It is also possible to use a twin screw extruder, for example a 28 mm Werner-Pfleiderer machine, thereby adding the 7903369 6 resin and the additives to the feed opening and the reinforcing material downstream thereof. In both cases, a generally suitable temperature in the machine is approximately 232 ° -238eC.

The pre-formulated mixture can be extruded and crushed into molding materials, such as conventional granules, tablets, etc., by conventional methods.

The composition may be molded in any conventional thermoplastic glass filler equipment, for example, a Newbury type injection molding machine having conventional cylinder temperatures, e.g., about 232 ° -275 ° C, and conventional mold temperatures, e.g., about 54 ° -66 ° C .

Preferred Embodiments

The invention is further illustrated by the following non-limiting examples.

15 EXAMPLES I-IV

Dry mixtures of poly (1,4-butylene terephthalate) resin (PBT), intrinsic viscosity 1.05 dl / g, melt viscosity 6200 poise, poly (ethylene terephthalate) (PET), intrinsic viscosity 0.62 dl / g, and with silane treated clay and mold release agent / stabilizer were formulated and extruded at 27 ° C in an extruder. The extrudate ..... * ..........

was granulated and injection molded at 271 ° C (mold temperature 54 ° C). The compositions and physical properties are listed in Table A: TABLE A - Compositions of polyesters and silane-treated clays.

Example 1A) IIIIII IV

Composition parts)

Poly (1,4-butylene terephthalate) 60 54 48 42 36

Poly (ethylene terephthalate 40 36 32 28 24

Silane-treated clay - 10 20 30 40 30 Properties:

Warp at room temperature <1 <1 <1 <1 <1 rature, mm

Warping after 30 min. At <20 7 2 1 1 177 ° C, mm 35 Impact resistance acc. Izod (without 6.0 4.2 7.7 5.1 3.7 notch), Joule / cm

Notch impact value according to Izod, 0.27 0.21 0.21 0.16 0.16

Joule / cm notch 7

Molding at 50 parts by weight of silane-treated clay per 100 parts by weight. parts of resin proved somewhat difficult. In all examples, the workability was excellent and the stability of the dimensions of the molded articles was greatly improved.

5 EXAMPLES V-IX

The general procedure of Examples I-IV was used to prepare compositions of poly (1,4-butylene terephthalate), poly (ethylene terephthalate) and acicular calcium metasilicate. The compositions used and the properties obtained are set forth in Table B below.

TABLE B - Compositions of polyesters and acicular calcium metasilicate. Example VA 1) V VI VII VIII IX

Composition (parts by weight)

Poly (1,4-butylene terephthalate 60 54 48 42 36 30 15 Poly (ethylene terephthalate) 40 36 32 28 24 20

Acicular Calcium Metasilicate - 10 20 30 40 50

Characteristics

Distortion temperature below 74 85 87 89 100 126

load of approx. 1820 kPa, ° C

20 Warp at room temperature <1 <1 <1 <1 <1 <1 temperature, mm

Warping after 30 min at <20 3 5 14 13 12 177 ° C, mm

Notched impact value acc. Izod, 0.27 0.27 0.27 0.32 0.37 0.37 Joules / cm

Impact resistance acc. Izod, 6.0 2.1 3.1 3.9 3.7 2.6 (without notch), Joule / cm 1) Control

All of the compositions of Examples V-IX could be molded very easily compared to the control material. In particular, the compositions of Examples V and VI were relatively warp-free and easy to process.

EXAMPLES X-XII

The general procedure of Examples I-IV was used to prepare glass fiber-reinforced compositions of poly (1,4-butylene terephthalate), poly (ethylene terephthalate) and a modifying agent, namely a combination of a segmented copolyester and an aromatic 7903369 - r, 8 pol polycarbonate. The compositions used and the properties obtained are set forth in Table C below: TABLE C - Reinforced compositions of polyesters, a segmented copolyester and an aromatic polycarbonate.

Example X XI XII

Composition (parts by weight)

Poly (1,4-butylene terephthalate 42.5 40 40

Poly (ethylene terephthalate) 30.0 30 30

Talc 15.0 15 15 10 Glass (reinforcement material) 10.0 10 10

Mixture of 60 parts of segmented 2.5% copolyester and 40 parts by weight. parts of aromatic polycarbonate

Mixture of 50 parts by weight of segmented copolyester and 50 parts by weight. parts of aromatic polycarbonate

Distortion temperature below 183 - 181

load of approx. 1820 kPa, ° C

20 Warp at room temperature, mm <. 1 <1 <1

Warp after 30 min. At 177 ° C, mm 9 10 8

Notched impact value according to Izod, Joule / cm 0.53 0.53 0.48

Impact resistance acc. Izdd (without notch) 4.4 4.6 4.5

Joule / cm 25 The compositions were very efficiently modified with the blends of segmented copolyester and aromatic polycarbonate, in particular as regards impact strength.

EXAMPLES XIII-XVII

The general procedure of Examples I-IV was used to prepare compositions of poly (1,4-butylene terephthalate), poly (ethylene terephthalate) and novaculite. The compositions used and properties obtained are given in Table D below.

- Table D - 7903369 9

B

TABLE D - Compositions of polyesters and novaculite.

Example XIIIA1 ^ XIII XIV XV XVI XVII

Composition (parts by weight)

Poly (1,4-butylene terephthalate) 60 54 48 42 36 30 5 Poly (ethylene terephthalate) 40 36 32 28 24 20

Novaculite 0 10 20 30 40 50

Characteristics

Warp at room temperature <1 1 <-1 <1 <1 <1 hour, mm 10 Warp after 30 min at <20 15 5 4 1 1 177 ° C, mm

Distortion temperature at approx. 74 76 75 78 90

1820 kPa, ° C

2)

Impact resistance according to Izod (without 6.0 5.9 4.4 N.B. 8.3 6.5 15 notch), Joule / cm

Notch impact value according to Izod, 0.27 0.27 0.27 0.27 0.27 0.27

Joule / cm 1) Control 2) No breakage. All compositions of Examples XIII-XVII could be easily molded. In particular, using 30 parts of novaculite and 40 parts of novaculite, the degree of warpage was low and good value for Izod impact strength (notched) was obtained.

25 EXAMPLES XVIII-XXV

The general procedure of Examples I-IV was used to prepare compositions containing poly (1,4-butylene terephthalate), aminosilane-treated clay and a segmented copolyester.

The compositions used and the properties obtained are shown in Table E below: - Table E - 7903369 i TABLE E - Compositions of polyester, glass fibers, copolyester with aminosilane b <0.

0 Example XVIII XIX | XX XXI XXII

CM i

Composition (w ~ w.dln)

Poly (1,4-butylene terephthalate) 58 48 i30 28 73 CO 30% glass fibers as filler 20 30 ι40 50 - containing poly (1,4-butylene terephthalate)

Clay treated with β-aminopropylsilane 14 14 14 14 14

Segmented copolyester 7 7 7 7 7

Glass fibers - - - - 6 E properties

Distortion temp. at approx. 159 149 171 177 140

1820 kPa, ° C

Warp at room temp. , mm <1 Ü <1 1 1

Warp after 30 min at 4 6 12 19 8 177 ° C, mm

Notched impact value according to Izod, 0.69 0.75 0.75 0.91 0.64

Joule / cm

Impact resistance according to Izod, 7.4 6.5 6.4 6.1 6.6 (without notch), Joule / cm

Flexural strength, kPa 101,350 115,140 {20,660 131,000 93,080 1!

Flexural modulus, kPa 3,385,330 4198,910 4164,440 4,936,650

Claims (17)

A thermoplastic material, comprising: (a) an intimate blend of a poly (1,4-butylene terephthalate) resin and a poly (ethylene terephthalate) resin, and (b) a modifier therefor in an amount of up to 60 parts by weight per 100 parts by weight (a) and (b), namely (i) a silane-treated clay; (ii) acicular calcium metasilicate; (iii) a combination of a segmented copolyester and an aromatic polycarbonate; or (iv) novaculate; or a mixture of two or more of these substances. The material of claim 1, wherein the modifier (b) is present in an amount of at least about 1.0% by weight based on (a) and (b). The material of claim 2, wherein the modifying agent (b) is present in an amount of about 2.5-50 wt% based on (a) and (b). A material according to claims 1-3, also containing reinforcing glass fibers in an amount of about 1-60% by weight, based on the combination of (a), (b). and the glass fibers. 5. The material of claim 4, wherein component (a) is formed by the intimate mixture of a poly (1,4-butylene terephthalate) resin and a poly (ethylene terephthalate) resin in which glass fibers are predispersed. 6. A material according to claims 1-5, wherein the polyester resins (a) have an intrinsic viscosity of at least about 0.4 dl / g, determined at 30 ° C in a solution in a mixture of phenol and trichloroethane (ratio 60 : 40), possess. The material according to claim 6, characterized in that the polyesters have an intrinsic viscosity of at least about 0.6 dl / g, determined at 30 ° C in a solution in a mixture of phenol, at a content of 79 0 33 c · Ί · * - § and trichloroethane (ratio 60:40). The material according to claims 1-7, wherein the poly (1,4-butylene-5 terephthalate) resin is linear or branched. The material of claim 8, wherein the branched polyester is a poly (1,4-butylene terephthalate) resin having a high melt viscosity and containing a minor amount of a branching component having at least three ester-forming groups. The material of claims 1-9, wherein the modifier (b) is a silane-treated clay. 10. CONCLUSIONS: The material of claim 10, wherein the modifier (b) is an aminosilane-treated clay. 12. The material of claims 1-9, wherein the modifier (b) is acicular calcium metasilicate. The material according to claims 1-9, wherein the modifier (b) is a combination of a segmented copolyester and an aromatic polycarbonate. A material according to claims 1-9, wherein the modifying agent (b) is novaculite. A thermoplastic material, comprising: (a) a poly (1,4-butylene terephthalate) resin, and (b) a modifier therefor, namely a combination of an aminosilane-treated clay and a segmented copolyester. Thermoplastic material according to claim 15, also comprising reinforcing glass fibers in an amount of about 1-60% by weight, based on the combination of (a), (b) and the glass fibers. 17. A thermoplastic material according to claim 16, wherein component (a) is formed by a pre-prepared dispersion of the glass fibers in the poly (1,4-butylene terephthalate). 7903369