WO2008151993A1

WO2008151993A1 - Transparent, thermoplastic, processable elastomeric polymer composition with uv stability and good adhesion properties

Info

Publication number: WO2008151993A1
Application number: PCT/EP2008/057083
Authority: WO
Inventors: Holger Wickel; Jens Dieter Erler
Original assignee: Kraiburg Tpe Gmbh & Co. Kg
Priority date: 2007-06-13
Filing date: 2008-06-06
Publication date: 2008-12-18
Also published as: DE102007027156A1

Abstract

The invention relates to a transparent, thermoplastic, elastomeric and UV-stable polymer composition which, as a two-component injection molding system, adheres to industrial thermoplasts, particularly to such thermoplasts with polar groups. This composition comprises three components: (a) an elastomeric block copolymer with at least two end blocks A of polymerized monoalkenyl aromatic compounds and at least one middle block B of polymerized and subsequently hydrogenated conjugated dienes and polymerized monoalkenyl aromatic compounds; (b) an end block-compatible resin; and (c) a middle block-compatible oil.

Description

description

Transparent, thermoplastically processable, elastomeric polymer composition with UV stability and good adhesion properties.

Subject of the invention

The invention relates to a transparent, thermoplastically processable, elastomeric polymer composition with UV stability and good adhesion properties on engineering thermoplastics, as well as the use of this composition for the production of composite parts.

State of the art

Various types of polymer compositions containing thermoplastic elastomers (TPE) based on alkenyl aromatic block copolymers are known.

Usual are styrene block copolymers (TPE-S), in particular triblock copolymers of the type ABA, consisting of two styrene end blocks A and a middle block B, for example, of a polymerized diene (polydiene) such as 1,3-butadiene { Styrene-butadiene-styrene, SBS) or isoprene (styrene-isoprene-styrene, SIS). The preparation of such triblock copolymers is disclosed, for example, in US 3,149,182. Also known MuItiblock polymers such as ABABA or radial polymers such as (AB) _n X with n> 2, wherein X is derived from a coupling reagent such as divinylbenzene or a silane (US 3,985,830).

The blndblöcke A different ABA polymer chains form below their glass transition temperature amorphous domains, - since the blndblöcke A are connected by the middle blocks B arises in this way a network structure of hard polystyrene domains and a soft B matrix, which causes the elastomeric character. Upon heating above its glass transition temperature, the A domains are reversibly softened and the polymer becomes thermoplastically processable. Since the indices of refraction of the polystyrene blocks and the center block are generally different per se, the optical properties such as transparency and light scattering are essentially determined by the size of the polystyrene moraines, which is essentially determined by the length of the blocks.

The polydiene midblocks can also be selectively hydrogenated to produce polymers with a saturated midblock. Such polymers are disclosed, for example, in US 3,595,942. For example, hydrogenation of SBS results in SEBS {styrene-ethylene / butylene-styrene}. In practice, more than 90% of the double bonds are reduced, as a side reaction even a small proportion (<10%) of the aromatic rings can be partially hydrogenated.

In addition to polydiene, which may optionally also be hydrogenated, the middle blocks can also contain polymerized styrene; For example, the distribution of styrene and diene in the midblocks may be randomly "C", "random", or "tapered." U.S. Patent No. 7,169,848 B2 discloses a specific type of monoalkenyl aromatic / diene distribution one or more regions of the B blocks adjacent to the A blocks have an above-average content of diene, while one or more regions not adjacent to the A blocks contain an above-average monoalkenyl aromatic content, moreover, the distribution is not blocky, which means that at most 40% of the monoalkenyl aromatic units in the B block have two monoalkenyl aromatic moieties as neighbors, the remainder having at least one diene moiety as neighbor The measurement of this property can be made by ¹ H-NMR as in US Pat No. 7,169,848 B2. Polymer compositions containing thermoplastic elastomers of the type alkenyl aromatic block copolymer and in the two-component injection molding on engineering thermoplastics, in particular those with polar groups such as PC, ABS, PC / ABS mixtures, PBT, PETG, Zylar or PMMA adhere also known. For adhesion to thermoplastics having polar groups, a further component which imparts adhesion is generally also required.

For example, US Pat. No. 5,149,589 discloses thermoplastic elastomer compositions of styrene block copolymers (TPE-S) which contain thermoplastic elastomeric co-polyesters (TPE-E) as a component which promotes adhesion. From 0S 5,472,782 also known compositions with thermoplastic elastomeric polyurethanes (TPE-U) as adhesion promoters. However, all of these compositions are opaque and not transparent.

Likewise are styrene-butadiene-styrene block copolymer

(SBS) based compositions on the market which contain as adhesion-conferring component an endblock-compatible resin. Such materials are transparent but only slightly UV stable; they turn yellow quickly under UV radiation.

Hydrogenated styrenic block copolymer compositions, e.g. By contrast, SEBS (styrene-ethylene / butylene-styrene) in combination with an endblock-compatible resin show inadequate adhesion to engineering thermoplastics having polar groups.

The use of hydrogenated styrenic block copolymers with styrene in the middle block for the production of elastomeric products is disclosed in US 2003/0181584 A1 and US 2003/0181585 A1. These are polymers with a controlled distribution of styrene and butadiene in

Middle block, as described in US 7,169,848 B2. The A blocks have number average molecular weights between The total content of monoalkenyl aromatic is 15-75% by weight (US 2003/0181584 A1) and 20-80% by weight, respectively -% (US 2003/0181585 A1).

It is also disclosed in the above references that these polymers have improved adhesion to polar polymers and can be used in conjunction with oils or adhesion-promoting resins. Such resins may be midblock compatible resins or endblock compatible resins. Some of the compositions disclosed in US 2003/0181584 A1 and US 2003/0181585 A1 are also transparent. However, no compositions are disclosed which are transparent at the same time, have good UV stability, and adhere well to polar thermoplastics.

WO 03/066769 A1 and US 2003/0176574 A1 disclose the use of hydrogenated styrene block copolymers with controlled styrene distribution in the middle block in

Combination with midblock and endblock compatible resins for the production of hot melt adhesives that adhere to polar and nonpolar thermoplastics.

task

The problem to be solved by the invention is to provide a thermoplastically processable, elastomeric composition which is transparent, has good UV stability, has very good mechanical properties such as high tensile strength, as well as on engineering thermoplastics, in particular on polar thermoplastics such as PC, ABS, PC / ABS compounds, PBT, PETG, Zylar or PMMA adheres well. invention

The above object is achieved by compositions comprising the following components:

(A) 100 parts by weight of one or more thermoplastic elastomeric block Cαpolymere having at least two end blocks A of polymerized monoalkenyl aromatic and at least one middle block B of polymerized and then hydrogenated conjugated dienes and monoalkenyl aromatic, wherein

the number average molecular weight of component (a) is between 80,000 and 240,000,

the number average molecular weight of the individual endblocks is between 10,000 and 36,000,

the proportion of monoalkenyl aromatic, relative to the weight of component (a), is 35-80%,

the proportion of monoalkenyl aromatic in the end blocks, with respect to the weight of component {a}, is 20-40%, and

the proportion of monoalkenyl aromatic in the middle blocks, in relation to the weight of the middle blocks, is 15-75%,

(b) 25 to 100 parts by weight of one or more endblock-compatible resins, and

(c) 40 to 150 parts by weight of one or more midblock compatible oils.

Such compositions adhere, for example in the

Two-component injection molding, good on engineering thermoplastics and especially on thermoplastics with polar groups. In addition, they are characterized by high transparency and UV stability. Typical are transmission values above 85% and haze values below 50%, preferably below 20%, according to ASTM D 1003, Method A, and at least 500 hours until the first signs of yellowing occur under UV radiation according to DIN EN ISO 4892-2.

The composition is e.g. for the manufacture of medical equipment, razor handles, switches, controls on equipment, mobile phones,

Toothbrush handles or toys and can, depending on the choice of proportions of the ingredients, in hardnesses between 20 and 90 Shore A are produced. Depending on the hardness, the tensile strength values are typically between 8 and 20 MPa.

Component (a)

The component consists of one or more thermoplastic elastomeric block copolymers having at least two end blocks A of polymerized monoalkenyl aromatics and at least one middle block B of polymerized and then hydrogenated conjugated

Serve and polymerized monoalkenyl aromatics,

The diene is, for example, 1,3-butadiene or substituted 1,3-butadienes such as isoprene, piperylene, 2,3-dimethyl-1,3-butadiene, 1-phenyl-1,3-butadiene, or else a mixture of different dienes, - butadiene is preferred. The monoalkenyl aromatic may be, for example, styrene, alpha-methylstyrene, para-methylstyrene, vinylnaphthalene, para-butylstyrene, or else a mixture of different monoalkenylaromatics; Styrene is preferred. The proportion of hydrogenated diene units is preferably 90% or greater; furthermore, up to 10% of the monoalkenylaromatics may also be hydrogenated or partially hydrogenated.

The middle blocks B preferably contain polymerized conjugated dienes and polymerized monoalkenyl aromatics in a controlled distribution, as in US Pat. No. 7,169,848 B2 described. In this case, one or more regions of the B blocks adjacent to the A blocks contain an above-average proportion of diene, while one or more regions not adjacent to the A blocks contain an above-average monoalkenyl aromatic content. In addition, the distribution is not blocky. Preferably, this means that at most 40% of the monoalkenyl-Aroraat "units in the B block have two monoalkenyl aromatic moieties as neighbors, the remainder having at least one diene moiety as neighbors.

In order to achieve high transparency and to achieve favorable values for softening temperature range and viscosity in terms of production and processing, a number average molecular weight between 80,000 and 80,000

240000, preferably between 100000 and 180000, even more preferably between 110000 and 160000, and most preferably between 120,000 and 140,000. From this weight, the weight of the end blocks accounts for 20-40%, preferably 25-35%. Furthermore, in view of good adhesion, a certain minimum weight of the end blocks is necessary, and a certain maximum weight, in order to ensure high transparency and good processability. Thus, the number average weight of a single endblock is between 10,000 and 36,000, preferably between 15,000 and 28,000, and more preferably between 18,000 and 22,000.

The molecular weights of the polymers can be measured by gel permeation chromatography (GPC) against polystyrene standards with chlorobenzene as the eluent.

The total amount of monoalkenyl aromatic, based on the weight of component (a), is 35-80%, preferably 40-70%, and most preferably 44-60%. Lower levels of monoalkenyl aromatic lead to no longer sufficient adhesion to polar thermoplastics, higher proportions reduce the elasticity. For high transparency and good adhesion to polar thermoplastics, the proportion of monoalkenyl aromatic in the B blocks, based on the weight of the B blocks, should be at least 15%; however, to ensure adequate elasticity and processability, 75% should not be exceeded. Preference is given to a proportion of 18-55%, and particularly preferred are 20-45%.

Suitable polymers are available, for example, from Kraton under the name "Kraton A".

Component (b)

The adhesion-promoting component is an endblock-compatible resin or a mixture of such.

Suitable examples are aromatic resins, such as homo- and co-polymers of vinyl toluene, styrene, alpha-methlystyrene, coumarone or indene. The weight-average molecular weight is preferably from 1000 to 40,000 in view of the hardness of the composition. Examples are coumarone-indene resins, polyindene resins, poly (methylindene) resins, polystyrene resins, vinyltoluene-alpha-methylstyrene resins, and alpha-methylstyrene resins. resins. Such resins are offered under the names "HERCURES", "ENDEX", "KRISTALEX", "NEVCHEM", "PICCOTEX" and "PICCOLASTIC". In particular, ENDEX 155 and KRISTALEX F115 (Eastman) with softening temperatures of about 155 and 115 ⁰ C are preferred.

There are used 25 to 100 parts by weight of the resin component, preferably 30 to 80 parts by weight, and particularly preferably 40 to 60 parts by weight. High resin contents increase the hardness of the composition and its adhesion to polar thermoplastics. For resin contents of less than 25 parts by weight, the adhesion becomes insufficient.

Component (c)

As middle block compatible oils, for example, vegetable oils or mineral oils can be used. Preference is given to paraffinic and / or naphthenic white oils. With regard to the use of the compositions for the

Manufacture of composite parts that must meet specific toxicological specifications, such as handles, particularly toothbrush handles, or food containers, medical white oils are particularly preferred. Such oils are offered, for example, by the company Shell under the name OHDINA.

The oil is contained at 40-150 parts by weight, preferred are 60-120 parts by weight. The larger the oil content, the softer the composition becomes. With more than 150 shares the adhesion decreases.

Other ingredients

Other ingredients may be added as long as they do not adversely affect the properties of the composition. Examples of these are further thermoplastic, monoalkenyl aromatic-block aromatic copolymers such as SBS, SIS or SEBS, as well as pigments, dyes, waxes, additional plasticizers, stabilizers and / or processing aids.

In particular, the composition may contain, in addition to the oil, a polyvinyl plasticizer, typically between 10 and 60 parts by weight. Suitable polymeric plasticizers are midblock-compatible, soft polymers, such as, for example, hydrogenated polydienes or copolymers of diene and monoalkenyl aromatic monomers, preferably of 1,3-butadiene and styrene, or else middle block-compatible resins, such as, for example, aliphatic, cycloaliphatic or hydrogenated aromatic hydrocarbon resins having preferred number average molecular weights between 200 and 1500.

Suitable middle block-compatible resins are commercially available, for example, under the names ESCOREZ, REGALITE or REGALREZ.

Preparation of polymer compositions

The polymer compositions according to the invention can be prepared and processed in the usual way.

The preparation of a granulate of the composition can be carried out, for example, by extrusion. the melt take place; preferred is the use of a

Twin-screw extruder. Typical speeds are between 250 and 450 min ^-1 and temperatures between 160 and 24O ⁰ C.

The granules of the composition can then be further processed, for example by injection molding, typically temperatures between 190 and 250 ⁰ C are used.

In particular, the composition is suitable for two-component injection molding processes for the production of composite parts with technical thermopolasts. Examples 1-4

Examples 1-4 demonstrate an embodiment of the invention. The weight proportions of the individual components are given in Table 1.

In Example 1, a mixture of the polymers "Kraton RP 6935 * and" Kraton RP 6936 "in the ratio 30/70 is used as component (a).

The molecular weight and styrene content averages of this mixture are also given in Table 1. Kraton RP 6935 is a hydrogenated styrene-butadiene triblock copolymer with controlled styrene distribution in the middle block and has a number average molecular weight (Mn) of about 210000. The styrene content is 58%, the end block styrene content is 30%. From these values result a number average molecular weight of each endblock of about 32,000, and a midblock styrene content, based on the number average molecular weight of the midblock, of 40%. The weight average molecular weights (Mw) are 240000 (total) and 36000 {final block, respectively).

Kraton RP 6936, also a hydrogenated styrene-butadiene triblock copolymer with controlled styrene distribution in the middle block, has a number average molecular weight of about 120,000, with a styrene content of 39% and an endblock styrene content of 30% the number-average molecular weight of the individual endblocks, each about 18,000, and a midblock styrene content, based on the molecular weight of the midblock, of 13%. The weight average molecular weights are 140000 (total) and 21000 (final block), respectively. The compositions in Examples 2-4 contain as component (a) the hydrogenated styrene-butadiene triblock copolymer Kraton EDF 8257, which has a controlled styrene distribution in the middle block and the number average molecular weight of which is 120000; the

The respective weight-average values are 130000 and 19500, respectively. The total styrene content is 58% and the middle-block styrene content, based on the weight of the middle block, is 40%.

The molecular weight determination of the polymers was carried out by means of gel permeation chromatography (GPC) from solutions with a concentration of 1 g / L with chlorobenzene as the eluent at a flow rate of 0.55 mL / min.

Calibration was carried out using polystyrene standards from PSS. Separation columns were three SDV Linear XL 20 μ with the dimensions of 8 mm x 300 mm from PSS used, the detection was carried out with a refractive index detector from Knauer.

"EHDEX 155" (Eastman) is an endblock-compatible aromatic hydrocarbon resin having a softening point of 155 ° C and a weight average molecular weight of about 9,000;

Kristalex F115 (Eastman) is an alpha-methylstyrene-based endblock compatible resin having a weight average molecular weight of about 2,000 and a softening point of about 115 ^° C .; the compositions are softer than with Endex 155.

"ONDINA 941" (Shell) is a medicinal white oil.

From the components, with the aid of a co-rotating Berstorff ZE25 twin-screw extruder, the Prepared compositions according to the invention. In this case, rotational speeds between 250 and 450 min ^-1 and temperatures between 160 and 24O ⁰ C were used, the throughput was 8-15 kg / h The resulting, transparent granules were then further processed by injection molding at 190-250 ⁰ C to test specimens for measuring the properties.

The test specimens for measuring the mechanical and optical properties as well as the UV resistance were produced with a Demag injection molding machine and stored for at least 16 hours before being subjected to the tests.

The hardness according to DIN 53505 / ISO868 was determined with conventional hardness testers. Tensile strengths (ZFS) and elongations at break (BD) according to DIN 53504 / ISO 37 and tear propagation resistances (WRW) according to DIN / ISO 34-1, method B (b) were measured with a Zwick ZO10 tensile tester.

Translucency ("transmission") and high-angle scattering

("Haze") of a 2 mm thick specimen of the compositions were determined according to ASTM D 1003, method A. For this purpose, a tester "haze-guard plus" from BYK was used. The UV stability was tested with a "Suntester" from Atlas according to DIN EN ISO 4892-2.

The adhesion of the compositions according to the invention to engineering thermoplastics was determined according to Renault Standard D41 1916. For this purpose, a 2 mm thick composite part with a technical thermoplastic, eg PC, ABS, PC / ABS, PBT, PETG or PMMA, as a hard component was produced on a Ferromatik MILLACRON 2K injection molding machine. The peel resistance was then measured with a Zwick tensile testing machine ZO10. For this purpose, the hard component was clamped in a movable carriage and fixed the consisting of the inventive composition elastomeric component with a clamp. The measurement was made at a pulling speed of 100 mm / min perpendicular to the adhesive surface.

Table 1

Examples 5-8

The compositions of Examples 5-8 (Table 2) were prepared and tested in the same manner as described in Examples 1-4.

Examples 5 and 6 contain a polymeric plasticizer called TSM (Taylored Softening Modifier). It is a hydrogenated copolymer of styrene and butadiene having a number average molecular weight below 80,000 and a weight ratio of styrene / butadiene of 40/60.

"ESCOREZ 5320" is a midblock-compatible resin which also functions as a polymeric plasticizer in Examples 7 and S. It is a cycloaliphatic hydrocarbon resin having a number average molecular weight of about 350 and a softening temperature of about 125 ° C.

Table 2

Claims

claims

A transparent polymer composition comprising the components

(a) 100 parts by weight of one or more thermoplastic elastomeric block copolymers having at least two endblocks A of polymerized monoalkenyl aroma, and at least one midblock B of polymerized and then hydrogenated conjugated dienes and monoalkenyl aromatics, wherein

the number average molecular weight of the individual end blocks is between 10,000 and 36,000, and

the proportion of monoalkenyl aromatic in relation to the weight of the component {a) is 35-80%,

- the proportion of monoalkenyl aromatic in the end blocks, in relation to the weight of component (a) is 20-40%, and - the proportion of monoalkenyl aromatic in the middle blocks in relation to the weight of middle blocks, 15 - 75% is

(b) 25 to 100 parts by weight of one or more endblock-compatible resins, and

(c) 40 to 150 parts by weight of one or more midblock compatible oils.

2. Polymer composition according to claim 1, wherein the middle blocks B of component (a)

contain more than average hydrogenated diene in one or more regions adjacent to the A blocks,

- above average in one or more regions not adjacent to the A blocks

Monoalkenyl-containing aromatics, and - have a non-blocky distribution of monoalkenyl aromatic.

The polymer composition of claim 1 or 2 wherein the number average molecular weight of component (a) is between 100,000 and 180,000.

The polymer composition according to one or more of claims 1 to 3, wherein the number average molecular weight of the individual end blocks of component (a) is between 15,000 and 28,000.

Polymer composition according to one or more of Claims 1 to 4, wherein the total weight fraction of monoalkenyl aromatic in component (a) is 40-70%, in particular 44-60%.

6. Polymer composition according to one or more of claims 1 to 5, wherein the weight proportion of monoalkenyl aromatic in the middle blocks of component (a), based on the weight of the middle blocks, between IS - 55%, in particular 20 - 45% ,

7. Polymer composition according to one or more of claims 1 to 6, wherein the weight proportion of monoalkenyl aromatic in the end blocks of component (a) is between 25-35%, in particular 30%.

8. The polymer composition according to one or more of claims 1 to 7, wherein component (a) consists of one or more linear triblock Compolymeren (ABA).

The polymer composition according to one or more of claims 1 to 8, wherein the diene in component (a) is 1,3-butadiene.

The polymer composition according to one or more of claims 1 to 9, wherein the monoalkenyl aromatic in component (a) is styrene.

The polymer composition according to one or more of claims 1 to 10, wherein component (b) is present in 40 to 60 parts by weight.

12. Polymer composition according to one or more of claims 1 to 11, wherein component (b) contains one or more homopolymers and copolymers of aromatic monomers, in particular vinyltoluene, styrene, methylstyrenes, coumarone or indene.

13. A polymer composition according to one or more of claims 1 to 12, wherein component (c) is present in 40 to 100 parts by weight.

Polymer composition according to one or more of claims 1 to 13, wherein component (c) is a paraffinic and / or naphthenic medicinal white oil.

The polymer composition of one or more of claims 1 to 14, which additionally contains up to 60 parts by weight of one or more midblock-compatible polymeric plasticizers.

16. Polymer composition according to one or more of claims 1 to 15, having a hardness between 20 and 90 Shore A.

17. Use of the polymer composition according to one or more of claims 1 to 16 for the production of composite parts between this polymer composition and engineering thermoplastics.

Use according to claim 17, wherein the engineering thermoplastics contain polar groups.

19. Use according to claim 17 or 18, wherein the composite part is produced in a multi-component injection molding process.