EP0519012A1

EP0519012A1 - Segmented block copolymers

Info

Publication number: EP0519012A1
Application number: EP19910907198
Authority: EP
Inventors: Reinoud Jaap Gaymans; Jeanette Louise Molenaar-De Haan
Original assignee: Dow Benelux BV; Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1990-03-06
Filing date: 1991-03-06
Publication date: 1992-12-23
Also published as: CA2077683A1; AU7660291A; WO1991013930A1; JPH05506680A

Abstract

Copolymère bloc segmenté comprenant des segments non cristallisables et des segments partiellement cristallisables, dans lesquels les segments partiellement cristallisables ont la formule -NH-R2-NH-[C(O)-R1-C(O)-NH-R2-NH]n-C(O)-R1-C(O)-[NH-R2-NH-C(O)-R1-C(O)]n- and/or -NH-R3-C(O)- ou un de leurs produits de réaction avec une diamine ou un acide dicarboxylique ou un dérivé d'un acide dicarboxylique, formule dans laquelle n est un nombre entier égal à 1, 2 ou 3, chacun de R1 et R2 sont indépendamment un groupe aliphatique, alicyclique ou entièrement ou partiellement aromatique, et R3 est un radical d'hydrocarbure pouvant être substituée ou non. Dans lesdits copolymères blocs les segments partiellement cristallisables ont une longueur de bloc sensiblement uniforme.Segmented block copolymer comprising non-crystallizable segments and partially crystallizable segments, in which the partially crystallizable segments have the formula -NH-R2-NH- [C (O) -R1-C (O) -NH-R2-NH] nC (O) -R1-C (O) - [NH-R2-NH-C (O) -R1-C (O)] n- and / or -NH-R3-C (O) - or one of their products of reaction with a diamine or a dicarboxylic acid or a derivative of a dicarboxylic acid, formula in which n is an integer equal to 1, 2 or 3, each of R1 and R2 are independently an aliphatic group, alicyclic or wholly or partially aromatic, and R3 is a hydrocarbon radical which may or may not be substituted. In said block copolymers, the partially crystallizable segments have a substantially uniform block length.

Description

Title: Segmented block copolymers

The invention relates to segmented block copolymers based on non- crystallizable segments and partly crystallizable segments . Depending on the type and properties of the materials constituting the blocks , such blockcopolymers may have different properties .

Block copolymers comprising non- crystallizable segments and partly crystallizable segments exhibit the behaviour of semi - crystalline polymers , the difference being that the T_g/T_m ratio is not invariably 0. 66 (the 2 /3 rule) , but may have a different value.

When this ratio is lower than 0 . 6 the materials usually have a thermoplastic elastomer character. At higher values the materials mostly behave as semi- crystalline polymers , such as PET, PBT, nylon 6 and the like. When the value for T_g/T_m exceeds 0 .7 for the semi - crystalline block copolymers , the materials have an improved balance of properties , since the range between T_g and T_m, in which range the modulus is from 3 - 20 times lower than the modulus below the T_g, is smaller. Thermoplastic elastomers consist in principle of two types of blocks , namely soft or flexible blocks and hard or non- f lexible blocks . The soft blocks are typically formed by amorphous flexible segments with a glass transition temperature of below 0° C . The hard blocks consist of crystallizable segments with a high melting temperature.

Thermoplastic elastomers behave as elastomers at temperatures below the melting temperature , while above that temperature a thermoplastic behaviour is found. Owing to this , these products are easy to process : easier, often, than pure elastomers , which often combine their elastomeric behaviour with difficult processability. Although thermoplastic elastomers possess a suitable property pattern, a decrease of mechanical properties occurs at temperatures approaching the melting temperature of the hard blocks, so that the temperature range within which the products can be used is fairly limited at the upper end.

In the plastics industry a great deal of research is done into engineering plastics, i.e. plastics with a property pattern, which makes it possible to use the plastic for construction purposes or under conditions of extreme temperatures. A number of such semi-crystalline plastics are based on polyesters, such as polybutyleneterephthalate, or on polyamides.

There is also a great need for plastics for the manufacture of fibers with improved properties. Although the known products for applications as engineering plastics and the manufacture of fibers have a suitable property pattern, a decrease of mechanical properties occurs at temperatures above the glass transition temperature, so that the temperature range within which the products can be used is fairly limited at the upper end.

An important problem which severely restricts the usability of engineering plastics resides in the fact that a decrease of the modulus occurs far below the melting temperature, so that at a low temperature a decrease of the properties and the usability occurs.

For amorphous engineering plastics a problem is that at temperatures a little above the glass transition temperature the melt processability is not yet optimal, which makes it necessary for the plastic to be processed at temperatures far above the glass transition temperature. This is -undesirable in view of polymer degradation and in view of energy consumption. It also means the cycle time is extended.

For the processing of polymers in general and of the present type of block copolymers it is of great importance that the crystallization rate during cooling is high. For crystallization to take place rapidly, a length of at least 4 recurring units in the crystallizable segment is known to be desirable (R.K. Adams, G.K. Hoeschele in Thermoplastic Elastomers ed. N.R. egge, G. Holden and H.E. Schroeder, Publ. Hanser ϋnchen, Chapter 8, page 163 (1987)). . With a length of more than 20 units, it is not possible anymore to obtain a homogeneous melt (melt-phasing) .

The object of the invention is .to provide new block copolymers, which do not possess the disadvantages described hereabove and which do have a number of advantageous properties hitherto not available.

These novel block copolymers can, among other things be used as fibre material or as an engineering plastic and exhibit a minor decrease of the modulus above the glass transition temperature, and a good melt processability at temperatures just above the melting temperature.

Block copolymers comprising hard, crystallizing segments and soft segments, having thermoplastic and elastomeric properties, can be employed advantageously in the automobile industry. The present invention is based on the surprising insight that by using short, uniform segments for the crystallizable blocks, the materials possess unusual high crystallization rates and the engineering plastics have improved properties.

Accordingly, the present invention relates to segmented block copolymers comprising non-crystallizable segments and partly crystallizable segments, in which the partly crystallizable segments have the following formula: -^•NH-R2-NH- [C(O) -Ri"C(0) -NH-R -NH]n" -C(O) -Rι-C(O) - [NH-R₂-NH-C(0) -R_x-C(0) ]_n- and/or

-NH-R₃-C (0) - or a reaction product thereof with a diamine or a dicarboxylic acid or a derivative of a dicarboxylic acid, in which formula n is an integer which equals 1 , 2 , or 3 , each of Ri and R₂ are independently an aliphatic , an alicyclic , or a wholly or partly aromatic group , and R₃ is a hydrocarbon radical which may or may not be substituted, and in which block copolymers the partly crystallizable segments have a substantially uniform block length.

In this connection 'a substantially uniform block length" means that virtually all partly crystallizable segments in the polymer have the same value for n. In practice, preferably a proportion of at least 70%, preferably at least 85% of all segments have the same length. More preferably, this proportion is at least 90%, and yet more preferably at least 97.5%. Such uniform block length can be obtained by a proper selection of the starting materials for the preparation of the block copolymer. This will be further explained when these materials are discussed.

Depending on the nature of the blocks used in the block copolymer, various products can be obtained. More in particular the block copolymers of the invention are thermoplastic elastomers and/or engineering plastics.

It is observed that in principle the products according to the invention have the following structures as regards the partly crystallizable segments: -NH-R₂-NH- [C(O) -Rj_.-C(0) -NH-R₂-NH]_n-

-C(O) -Ri-C(O) - [NH-R₂-NH-C(0)-Rι-C(O)]_n-

However, it is possible to replace these in whole or in part with -NH-R₃-C(0)- or a reaction product thereof with a diamine or a dicarboxylic acid or a derivative of a dicarboxylic acid.

Surprisingly, it turned out that a segmented block copolymer which meets these conditions exhibits a much higher degree of crystallization, and the crystallization itself takes place much faster, which is a great advantage from process- economical considerations.

According to a first embodiment the flexible segments have a glass transition temperature <0° C. These block copolymers possess thermoplastic properties and the degree and the rate of crystallization of these copolymers is higher than of block copolymers not according to the invention. To obtain an optimally segmented block copolymer, in a preferred embodiment of the invention one starts from a hard block, which as such, i.e. as an oligomer with amide groups, exhibits a crystalline structure at temperatures below the melting point.

The melting temperature of the segmented block copolymer of this embodiment is preferably > 100°C, more preferably > 150°C, so as to guarantee optimum usability. The melting temperature can be set through the appropriate selection of n, Ri, R , and optionally R₃.

It turned out that owing to the low concentration^' of non-flexible segments, which are dissolved in the soft or non- crystalline phase, the segmented block copolymer according to the invention exhibits a very good phase separation, i.e. a very good separation of the flexible and the non-flexible phases, while a low glass transition temperature of the soft or flexible phase is retained. Further, a high degree of ordering of the hard phase occurs. However, one of the most important properties of the products of the invention is that the course of the modulus at temperatures above the glass transition temperature of the soft phase depends on the temperature to a minor extent only. In practice it has been shown possible to employ service temperatures which are fairly close to the melting temperature of the hard, non-flexible phase. To achieve a good impact resistance of the block copolymers according to this first embodiment of the invention, especially at low temperatures, it is essential for the glass transition temperature of the soft blocks to be < 0°C, preferably < -25°C, and more preferably < -45°C. The flexible block is formed by the usual flexible segments, which consist of a, preferably difunctional, linear polymer having a molecular weight of 200-4000. This polymer has rubbery properties after incorporation into the block copolymers according to the invention, which is reflected in its glass transition temperature, among other things. Particularly suitable are segments of polyesters and polyethers , preferably based on ethylene oxide , propylene oxide, butyl ene oxide, copolymers , or block copolymers of two or more of those , or hydrogenated or unhydrogenated polybutadiene and polyisobutylene . In general the flexible segments may be hydroxyl - , carboxyl- , or amine - terminal . Naturally, the nature of these terminal groups of the flexible block may affect the choice of the hard block, because certain combinations of terminal groups need not necessarily be reactive with all hard blocks . In another embodiment of the invention the glass transition temperature of the block copolymer is > 0°C.

These materials have typical engineering plastic properties and can also be used as fiber material .

It turned out that the segmented block copolymers according to this embodiment of the invention, i . e. . with short uniform blocks and short non- crystallizable blocks , have a combination of a T_g > 0°C , a T_g/T_m > 0 . 6 and a high crystallization rate .

The non- crystallizable segment pref erably has a molecular weight of 20 to 400 , more preferably of 40 to 250 . Particularly suitable are aliphatic or alicyclic diols , diamine , aminoalcohσls , diacids , amino acids hydroxy acids hydroxyl -terminal chains and the like.

The melting temperature of the segmented block copolymer of this embodiment of the invention is preferably > 160°C so as to guarantee optimum usability. The melting temperature can be set by the appropriate selection of n, R_{i f} R₂ and R₃.

In a third embodiment of the invention the glass transition temperature of the block copolymer is > 130°C. It turned out that such segmented block copolymers according to the invention exhibit very good mechanical properties such as tensile strength, impact resistance , dimensional stability, good tribologic properties and a good solvent - resistance . Further, these products have a high modulus up to the glass transition temperature and a reasonably high modulus between the glass transition temperature and the melting temperature if it is higher. Furthermore, the block copolymers according to this embodiment exhibit a good melt processability at temperatures which are only some tens of degrees above these two transition temperatures.

In practice it has been shown possible to employ service temperatures which come fairly close to the melting temperature of the block copolymer.

The block- copolymers according to this embodiment of the invention, which are built up from blocks with amorphous segments and with semi-crystalline segments have a glass transition temperature of at least 130°C, more preferably at least 150°C. The melting temperature of the segmented block copolymer according to this embodiment is preferably > 200°C so as to guarantee optimum usability. The melting temperature can be set by the appropriate selection of n, R_lf R₂,and/or R₃. The T_g/T_m ratio (in K) is preferably at least 0.6, more in particular at least 0.7, because then the temperature range, i.e. between T_g and T_m, where the modulus decreases, is minimized.

The block copolymers according to this embodiment can be obtained with copolymers built up from segments with an irregular chain pattern and segments with a regular chain pattern. At service temperature these block copolymers have a multiphase structure, comprising one or more amorphous phases and a partly crystalline phase.

As segments for the amorphous phase, i.e. the phase with a low degree of order, one may use, for example, alicyclic/aromatic diols, diamines, aminoalcohols, diacids aminoacids and/or hydroxyacids with a molecular weight between 70 and 5000.

As amorphous segments, for example, segments with a molecular weight of at least 70 are used, for example polyamides, polyesters, amorphous esters, hydroxyl-terminal ketones,imides, amides, for instance semi-aromatic ketones, wholly or partly aromatic esters, amides and imides. In general it is advantageous to use segments which yield a high glass transition temperature.

Although for each embodiment disclosed hereabove the choice of the various components for preparing the block copolymer has to be made independently, some general remarks about materials and conditions to be used can be made. Materials and conditions mentioned below apply only in so far as they are not defined differently hereabove for the various embodiments. The value of n is preferably 1 or 2, because that permits the best possible uniform packing of the chain parts in the crystal. For Ri one can choose from an aliphatic, alicyclic or wholly or partly aromatic group, such as a paraphenyl or a naphthyl group, depending on the dicarboxylic acid chosen. A paraphenyl or a 2,5-, or a 2,6-naphthyl group is preferable.

R₂ is an aliphatic, alicyclic or wholly or partly aromatic group and preferably a lower, linear alkyl group with 2-8 carbon atoms. More preferably, ethylene, butylene, hexylene or octylene groups are used because they yield the best results. For R₃ preferably an aliphatic, aromatic, cycloaliphatic, aralkyl or alkaryl radical which may or may not be substituted is used.

In this connection the term 'aromatic group or wholly or partly aromatic group' includes groups in which two or more aromatic rings are connected with each other by a non-aromatic group, including non-hydrocarbon groups, such as ether bonds and the like.

The preparation of the starting products for the segments can be carried out in known manner, by reacting the diamine and the dicarboxylic acid or derivative thereof. In a preferred embodiment, as a diamine preferably 1,2- diaminoethane, l,4-diaminobutane, 1, 6-diaminohexane, 1,8-diaminooctane or paraphenylenedia ine is used. The dicarboxylic acid to be used is preferably terephthalic acid, but it is also possible to use 2,6-naphthalenecarboxylic acid. In a first variant of the invention, which concerns the use of an ester-terminal block, a diester-diamide is prepared by reacting a diamine with a molar excess of diester of a dicarboxylic acid, such as dimethylterephthalate. In general it will be preferable to use at least a double excess. The^' reaction is preferably carried out in the presence of a catalyst, such as Li(OCH₃). The use of a catalyst is not requisite, but generally does promote the reaction positively. When the reaction is carried out starting from a mixture of all components, which is supplied to the reactor prior to the beginning of the reaction, if desired, a fairly large excess of diester can be used, optionally followed by a fractioning of the product obtained. However, it is also possible to initially supply the diester and to gradually add the diamine, so that in principle there will always be an excess of diester present in the reactor. In such a case, it will be sufficient to use a small excess in the total amounts to be used. It is also possible to start from the diamine and p-carboalkoxy-benzoyl chloride. To prepare the starting product for an amide-terminal crystallizable block in a second variant of the invention, a similar procedure may be followed, except that the diamine and the dicarboxylic acid are changed round.

A mixture of this starting product for the crystallizable block, and the starting product for the amorphous segment is then condensed to form a prepolymer. This prepolymer can finally be after-condensed to form a segmented block copolymer with the desired properties.

For the prepolymerisation the conditions known from the literature can be used. When the amorphous segment is hydroxyl- terminal, the methods of preparing polyester-based segmented block copolymers can be used. When the amorphous segment is amine-terminal, the methods of preparing polyamide-based segmented block copolymers can be used. Preferably the prepolymerisation is carried out for 15- 60 min at a temperature < 225°C, at a pressure > 0.75 bar, followed by maintaining the temperature at a value of ≥ 200°C for at least 60 min, at a^' pressure < 0.1 bar. More preferably, this second phase can be carried out in such a way that first the temperature is raised to a value between 200 and 300°C, at a^* pressure between 10 and 50 mbar, for 10-45 min, and then is carried out at a temperature ≥ 220°C and at a pressure ≤ 5 mbar, for 45-120 min.

In a conventional manner the prepolymer thus obtained is after-condensed in solid state at a temperature between 150°C and a temperature of some degrees below the melting point of the polymer, in the presence of a noble gas.

The segmented block copolymers according to the invention can be processed into objects in the conventional manner, for example by injection moulding at a temperature above the melting point. The conventional techniques are also used for processing the present copolymers, where appropriate, to form fibres. Also, the conventional additives may be incorporated into the polymer, such as colouring matter, pigments, UV stabilizers, heat stabilizers, as well as fillers, such as soot, silicic acid, clay or glass fibers. It is also possible to mix the products according to the invention with one or more other plastics.

The invention will now be illustrated in and by the following Examples without prejudice to the scope of the invention.

EXAMPLE 1

A segmented block copolymer was prepared starting from a hydroxyl-terminal polytetramethylene glycol having a molecular weight of 250, and a diester-diamide prepared in the following manner.

A mixture of l mol 1, -diaminobutane and 2.5 mol dimethylterephthalate was initially supplied to a reactor and then reacted in the presence of Li(OCH₃). Thus a diester- diamide with one diamide block was obtained, terminated with two diester blocks. The segmented block copolymer was prepared from these two components by polycondensation for 30 min at 160°C and 1 bar. Then the reaction product was heated to 250°C and at that temperature condensed for 10 min by means of a vacuum created by a water jet pump and for 60 min by means of a vacuum created by an oil vacuum pump (0.05 mm Hg) .

The block copolymer obtained had an ηin in m-cresol

(0.5% solution at 25°C) of 0.65, a τ_g (G'max) at 39°C, a τ_m at

179°C (measured in DSC at a heating rate of 20°C/min, second heating) and a (T_m-T_c) (difference in melting and crystallization temperature at heating and cooling rates- of 20°C/min) of 10°C.

EX MPLE 2

A segmented block copolymer was prepared in the manner described in Example 1 using the same diester-diamide and a mixture of diols. Per mole diester-diamide 0.5 mol hexanediol and 0.5 mol octanediol were used, dissolved in ethanediol. The block copolymer thus obtained had an m-n of 0.42, and one of

0.49 after 24 h of after-condensation at 150°C in the solid phase under nitrogen.

The block copolymer had a T_g of 103°C, a T_m of 229°C and a T_m-T_c of 32°C.

EXAMPLE 3

A segmented block copolymer was prepared in the manner described in Example 1 using the same diester-diamide and l mol

1,4-bis (hydroxymethyl)cyclohexane dissolved in ethanediol per mol diester-diamide. The block copolymer thus obtained had a ηin_h of 0.29, and one of 0.47 after 24 h of after-condensation at 200°C in the solid phase under nitrogen. The block copolymer had a T_g of 114°C, a T_m of 231°C and a T_m-T_c of 19°C. EXAMPLE 4 anr^*! Comparative Examples 1 and 2

A segmented block copolymer was prepared starting from a hydroxyl-terminal polytetramethylene glycol having a molecular weight of 700, and a diester-diamide prepared in the following 5 manner.

A mixture of l mol l,4- ia inobutane and 2.5 mol dimethylterephthalate was initially supplied to a reactor and then reacted in the presence of i(OCH₃). Thus a diester- diamide with one diamide block was obtained, terminated with

10. two diester blocks.

The segmented block copolymer was prepared from these two components by polycondensation for 30 min at 160°C and l bar. Then the reaction product was heated to 250°C and at that temperature further condensed for 10 min by means of a 15 vacuum generated by a water jet pump and for 60 min by means of a vacuum generated by an oil vacuum pump (0.05 mm Hg) .

The block copolymer (A) obtained had the properties listed in the Table.

For the purpose of comparison a product was prepared 20 starting from the same diol, but with dimethylterephthalate only. The properties of the resultant polymer (B) are also listed in the Table. (Comparative Example 1)

Further, a segmented block copolymer was made with 1 mol of the same polyether, 5 mol dimethylterephthalate and excess 25 1,4-butanediol (12 mol). This is the comparative polymer C. (Comparative Example 2)

Further, torsion damping curves were made for these products. These curves are represented as Figs 1, 2 and 3, where Fig. l concerns the product according to the invention, 30 and Figs 2 and 3 concern the comparative products B and C. These Figures clearly show what the advantages are of the segmented block copolymer A according to the invention. TABLE

* G'₂₀/G'ιoo;^Decrease in the modulus of shear between 20 and

100°C

** Crystallization temperature; cooling rate 20°C/min

*** Melting temperature; 2^nd heating curve; heating curve 20°C

**** Not perceptible

@ Calculated on the hard phase

Claims

LAIMS

1. A segmented block copolymer comprising non- crystallizable segments and partly crystallizable segments, in which the partly crystallizable segments have the following formula: -NH-R₂-NH- tC(O) -Ri-C(O)-NH-R₂-NH]_n-

-C(O) -Ri-C(O) - [NH-R₂-NH-C(0) -Rι-C(O) ]_n- and/or

-NH-R₃-C(0)- or a reaction product thereof with a diamine or a dicarboxylic acid or a derivative of a dicarboxylic acid, in which formuia n is an integer which equals 1, 2, or 3, each of Ri and R₂ are independently an aliphatic, an alicyclic, or a wholly or partly aromatic group, and R₃ is a hydrocarbon radical which may or may not be substituted, and in which block copolymers the partly crystallizable segments have a substantially uniform block.length.

2. A block copolymer according to claim l, wherein that at least 70%, and preferably at least 85% of all partly crystallizable blocks have the same length.

3. A block copolymer according to claim 2, wherein that at least 90%, and preferably at least 97.5% of all partly crystallizable blocks have the same length.

4. A block copolymer according to claim 1-3, wherein it is a fast crystallizing material.

5. A block copolymer according to claim 1-4, wherein the melting point is at least 100°C, and preferably at least 150°C.

6. A block copolymer according to claim 1-5, wherein the melting point is at least 160°C, preferably at least 200°C.

7. A block copolymer according to claim 1-6, wherein the glass transition temperature of the flexible blocks is < 0°C.

8. A block copolymer according to claim 7, wherein the glass transition temperature of the flexible block is < -25°C, and preferably < -45°C. lb

9. A block copolymer according to claims 1-8, wherein R_x is a paraphenyl or a naphthyl group.

10. A block copolymer according to claims 1-9, wherein R₂ is a C₂-C₈-alkyl group.

11. A block copolymer according to claims 10, wherein R₂ ^■ is an ethylene, a butylene, a hexylene or an octylene radical.

12. A block copolymer according to claims 1-6, wherein its glass transition temperature is > 0°C.

13. A block copolymer according to claim 12, wherein its glass transition temperature is > 40°C.

14. A block copolymer according to claim 12 or 13, wherein the non-crystallizable block has an average molecular weight of 20 to 400, preferably of 40 to 250.

15. A block copolymer according to claims 1-6, wherein its glass transition temperature is > 130°C.

16. A block copolymer according to claim 15, wherein the T_g/T_m ratio (in K) is at least 0.6, preferably at least 0.7.