WO2007094654A1

WO2007094654A1 - Process for the preparation of segmented copolymers containing polyamide segments

Info

Publication number: WO2007094654A1
Application number: PCT/NL2006/000077
Authority: WO
Inventors: Reinoud Jaap Gaymans; Debby Husken; Edwin Biemond
Original assignee: Stichting Dutch Polymer Institute
Priority date: 2006-02-14
Filing date: 2006-02-14
Publication date: 2007-08-23

Abstract

The invention relates to a process for the preparation of segmented copolymers having segments comprising 4 or more amide groups, comprising the steps of [i] mixing a component A having a segment comprising 4 or more amide groups and one or more reactive endgroups with a component B, having one or more endgroups that may react with the reactive endgroups of component A, [ii] heating the mixture to a reaction temperature which is above the melting temperature of component A, whereby a reaction starts between component A and B, wherein the process is carried out in the absence of a solvent and wherein the component A has a melting temperature between 100 and 270 °C.

Description

PROCESS FOR THE PREPARATION OF SEGMENTED COPOLYMERS CONTAINING POLYAMlDE SEGMENTS.

The invention relates to an improved process for making segmented copolymers containing polyamide segments.

A process for making segmented copolymers containing polyamide segments is known from WO 03/070807. This reference discloses the synthesis of copolymers containing polyamide segments, wherein the polyamide segments contain between 3 and 7 amide groups. These copolymers are prepared by mixing reactive components in the presence of a solvent (for example N-methylpyrolidon (NMP)), heating the mixture, and continuing the polymerization in the melt, after evaporation of the NMP. The copolymer in WO 03/070807 has polyamide segments that are rather uniform in length. This has the advantage that crystallization is fast and complete, which results in good polymer properties. The process as disclosed in WO 03/070807 has the disadvantage of providing copolymers having a brownish color.

It is an object of the present invention to provide an improved method of preparation for copolymers having uniform polyamide segments of at least 4 amide groups per segment. The present invention solves the problems by providing a process for the preparation of segmented copolymers having segments comprising 4 or more amide groups, comprising the steps of

[i] mixing a component A having a segment comprising 4 or more amide groups and one or more reactive end groups with a component B, having one or more end groups that may react with the reactive end groups of component A,

[ii] heating the mixture to a reaction temperature which is above the melting temperafeare of component A, whereby a reaction starts between component A and B, wherein the process is carried out in the absence of a solvent and wherein the component A has a melting temperature between 100 and 270 ⁰C.

The process of the present invention has the advantage of providing polymers in an excellent yield, with an improved color. An additional advantage is that copolymers are obtained having a high molecular weight (or high intrinsic viscosity). Another advantage is that the process is very simple, due to the fact that no solvent is used, and the process is therefore also more environmentally friendly. The invention also relates to a copolymer represented by formula I

-(-Y-Amide- (R-Amide-) n-) m- (I)

wherein each amide represents an N (H) C (O) or C (O) N (H) group, wherein each R is independently chosen from the group consisting of alkylene moieties, alicyclic moieties and arylene moieties, wherein n has an average value of at least 3, wherein m has a value of at least 1 , wherein Y represents a chain segment and wherein the copolymer has a L-value between 87 and 100 in the L*a*b colorspace. The reaction temperature in step [ii] of the process of the invention is preferably 0-30 ⁰C above the melting temperature (Tm) of the component A, more preferably 5-20 ⁰C above the Tm of component A.

The process of the invention may contain additional steps, like for example a reaction step [Hi], that takes place at a temperature between 200 and 270 ⁰C and wherein a vacuum may be applied to the reaction mixture to remove volatile reaction products, like for example methanol. Preferably the temperature in reaction step [iii] is between 220 and 260 ⁰C.

The reaction of component A with component B is preferably carried out in the presence of a catalyst. The catalyst may be any condensation catalyst known in the art, like for example organometallic compounds. Non-limiting examples of such catalysts are Titanium isopropoxide, Titanium isobutoxide, Lanthanum trisacetylacetonate and Tin acetate.

The process of the invention preferably relates to the synthesis of copolymers represented by formula I

- (-Y-Amide- (R-Amide-) n-) m- (I)

wherein each Amide represents an N (H) C (O) or C (O) N (H) group wherein each R is independently chosen from the group consisting of alkylene moieties, alicyclic moieties and arylene moieties, wherein n has an average value of at least 3, more preferably from 3-6, wherein m has a value of at least 1 , preferably an average value of at least 2, more preferably of at least 3. Preferably 30-100 mol %, preferably 50-100 mol % and more preferably 70-100 mol% of the Amide- (R-Amide-)" segments are uniform in length. Preferably the amide is based upon an aliphatic or alicyclic amine. Each Y represents a chain segment. The glass transition temperature of the polymer is preferably below 0 ⁰C, more preferably below -30 ⁰C.

The copolymers are prepared by copolymerizing component A having on average 4 or more amide groups and one or more reactive end groups with a component B, which contains a chain segment and reactive end groups, that will react with the reactive end groups of component A. The chain segment Y defined above comprises the chain segment of component B and the reacted end groups of component B and component A.

The reactive end groups present in component A and B (not shown in I) can have any structure. The end groups may for example be chosen from the group consisting of hydroxyl groups, amines, acids, ester groups, groups as defined for Y and/or amide groups.

The shear modulus (G') as used herein is defined as the torsion storage modulus determined by Dynamic Mechanical Analysis(DMA) at 1 Hz and measured in a temperature sweep of 1 °C/min according to DIN 53445 with the exception that 2 mm thick samples are used.

The glass transition temperature (Tg) as used herein is defined as the temperature at which the loss modulus G" has a maximum as determined by DMA according to the above indicated modified DIN 53445 method. Unless indicated otherwise, when referred to Tg of a polymer or composition having more Tg's, the primary Tg is meant, the transition with the highest loss modulus (G") value.

The compression set as used herein is the value as determined according to ISO 815 with a 25% compression is and the relaxation time of 30 minutes.

The Tm as used herein is defined as the melting temperature as measurable by differential scanning calorimetry (DSC) at a scan rate of 20 °C/min. For polymers, the Tm is determined in the second heating scan which is taken after first warming the sample to 20 ⁰C above the melting temperature, cooling with 20 °C/min down to 50 ⁰C and reheating at 20 °C/min. The peak maximum is taken as the melting temperature. A copolymer prepared according to the process of the invention has a high uniformity. The uniformity of the amide segment (-Amide- (R-Amide-) n-) is found to be important for the phase structure. It is known that very short segments are easily miscible with the Y segment and somewhat longer segments phase separate in the melt. The presence of dissolved amide segments in the Y phase increases the Tg of the Y phase and that is not wanted. Phase separated amide segments in the melt, make the synthesis more difficult, gives the polymer an extra Tg (of the polyamide phase), a broad melting transition, a slow crystallization from the melt and a low crystallinity of that segment, all of which are not wanted. By using segments with a high uniformity it has been found possible to allow a higher amide content in the polymer before melt phasing takes place. A higher amide content results in a higher melting temperature and a higher modulus. Another advantage of more uniform segments is a faster and more complete crystallization of the amide segment, which is important for the ease of processing, the effectiveness of the amide segment for increasing the modulus and the modulus sensitivity to temperature.

The uniformity of component A is preferably > 30%, more preferably > 70%, or 90%. The uniformity is determined from 1 H-NMR as explained in the experimental part of the description. A copolymer according to the present invention has been found to have a modulus, which is, very little dependant on temperature in the temperature range between room temperature and the melting temperature.

The copolymer prepared in the process according to the present invention shows an improved color compared to copolymers prepared in a process wherein a solvent is applied. The color of the copolymer may be defined with the aid of the L*a*b colorspace.

Measurement of color can be performed with a Chroma meter. In case the copolymer is opaque (due to for example the presence of a filler), the color of the copolymer is measured with a Chroma meter on the copolymer as such. When the copolymer is transparent, measurement of the color is performed against a white background. A Chroma meter will give three values in the L*a*b color space (CIELAB 1976). The lightness (L) will be 100 for white materials and 0 for totally black materials. The 'a' and 'b' values represent the actual color: The '-a' value represents green, '+a' represents red, '-b' represents blue and '+b' is yellow. The 'a' value is preferably between -10 and +10, more preferably between -5 and +5; the 'b' value is preferably between -10 and +15, more preferably between -5 and +10.

The copolymers of the present invention preferably have L-values between 87 and 100, more preferably between 90 and 100, most preferably between 93 and 100.

The present invention also provides a copolymer which depending on the amide concentration can have a wide range of moduli. In an embodiment the storage shear modulus (G') at room temperature (20 ⁰C) is between 0.1- 500 MPa and preferably between 0.5-250 MPa. A copolymer with a shear modulus of less than 40 MPa, e. g with a shear modulus of 1-20 MPa, is very suitable for applications as in elastic fibers and for providing products with a "soft touch", such as knobs, handles, switches and the like, e. g. for electric equipment, tools, casings, doors, clothing or other products that are touched by hand or skin.

In a preferred embodiment the melting temperature is at least 130 ⁰C, more preferably higher than 150 ⁰C, even more preferably higher than 180 ⁰C. A high melting temperature is important for applications were a high temperature resistance is required, like in the automotive, electrical, electronic and industrial sector. A high temperature resistance is also very important for the elastic fibers as the dying of fibers is often at high temperatures. A much preferred copolymer has both a low shear modulus of less than 20 MPa and a melting temperature of more than 150 ⁰C, or even more than 180 ⁰C. A copolymer prepared according to the process of the invention has amide segments which crystallize fast on cooling from the melt. Even a polymer with a low amide (-Amide- (R-Amide-) n-) content (less than 30 wt. %) is able to crystallize fast.

As a result, a copolymer prepared according to the process of the invention is well processable, e. g. by extrusion, injection molding, blow molding and fiber spinning. A measure for the rate of crystallization is the difference between the melting temperature and the crystallization temperature (Tm-Tc) both measured by DSC at a scan rate of 20 °C/min. For a polymer that is to be processed by extrusion, injection molding or fiber spinning the Tm-Tc value is advantageously less than 50 ⁰C, preferably less than 40 ⁰C and more preferably less than 30 ⁰C. The lower this value the faster the crystallization is and this is very important for fast processing of the materials.

A copolymer prepared according to the process of the invention has one or more amide segments which have a high crystallinity so that the modulus increases with concentration and said polymer is generally substantially stronger than known segmented copolymers. The amide (-Amide- (R-Amide-) n-) content (wt %) has a direct effect on the modulus and can be less than 60 wt%, preferably less than 50 wt. % and more preferably less than 40 wt. %.

For a very soft grade (G' < 20 MPa) the content of amide segments is typically less than 20 wt.%.

A copolymer prepared according to the process of the invention shows a very favorable solvent resistance, in particular against solvents such as hydrocarbons, chlorinated hydrocarbons, petrol, alcohols, ethers, esters, ketones and the like, which is important for automotive and industrial uses.

A copolymer prepared according to the process of the invention shows a good resistance against detrimental influences of inorganic salts, which is for example advantageous when such a polymer is used in an automotive application, because of the possible exposure to salt that has been used to grit roads. The melting temperature for the polymers prepared according to the process of the invention is much sharper than for a polymer wherein the distribution of the amide segment length is random. This is found to be an advantage in the melt processing of the materials.

Surprisingly it has been found that a copolymer prepared according to the process of the invention has a very low compression set compared to known amide-TPE materials both at room temperature and high temperatures. The compression set at 20 ⁰C as function of the shear modulus at 20 °C is less than (10 + 0.5 x Shear Modulus (in MPa)).

A copolymer prepared according to the process of the invention has shown to have very favorable tensile elastic properties. In particular, it has been found that in a preferred embodiment a copolymer prepared according to the process of the invention has a tensile set (TS300%) in a cyclic deformation test after 300 % strain, of less than (30 log (shear modulus (in MPa) ) +0.2).

A polymer prepared according to the process of the invention has these good elastic properties both on unoriented and oriented samples.

A polymer prepared according to the .process of the invention has a high fracture strain and/or a high elasticity. In particular, a polymer displays a homogeneous deformation on straining and a high elongation at break value. The absence of strain softening with the large fracture strain means that the polymer has a ductile deformation behavior and a high fracture energy.

Surprisingly it has been found that, despite a copolymer prepared according to the process of the invention being semi-crystalline-it may still be transparent.

Transparency is for many applications a highly valued property. As can be understood from the properties indicated above, a copolymer prepared according to the process of the invention may have a variety of favorable properties. Thus, the present invention provides a range of polymers, which depending upon their specific properties, may be employed in a variety of application areas, including e. g. automotive (boots, safety hatches, seals, headlight housing), consumer (snow boards, ski shoes, springs, in-line skates), electrical/electronic (protective coverings, water seals) and industrial (low noise gears, pumps, conveyer belts). A copolymer can also be used for fiber applications and for molding. A polymer may also be used as (impact) modifier in blends, such as polyamides, polyesters, polyethylene, polypropylene, polyurethanes, polyacetal, polycarbonate, polystyrene, polycarbonate, poly (phenylene ether), polyesterethers, polyurethanes, polyureas, SBS, SEBS copolymers, PP-EPDM/EPR, PP- EPDM/EPR dynamic vulcanizates, rubbers and/or copolymer and blends of these polymers.

In a preferred embodiment, at least a major part of the amide segments is formed of tetra-amide segments (n=3). Very suitable polymers prepared according to the process of the invention are polymers wherein the amide segments Amide- (R-Amide-) n are chosen from the group consisting of-C (O) N(H)-R2-N (H) C (O)-R3-N (H) C(O)- ;- N (H) C(O)-Ri-C (O) N(H)-R3-C (O) N (H)-C (O) N (H) -R2-N (H) C(O)-RI-C (O) N(H)-R2-N (H) C (O)-; -C(O) N(H)-R3-C (O) N(H)-R2-N (H) C(O)-R3-N (H) C(O)- ;- N (H) C(O)-Ri-C (O) N (H) -R2-N (H) C(O)-Ri-C (O) N (H)- -N (H) C (O)-R3- N (H) C(O)-RI-C (O) N(H)-R3-C (O) N (H)-, wherein each Ri, is independently chosen from the group consisting of alkylene moieties, alicyclic moieties and arylene moieties and each R2 and R3 is independently chosen from the group consisting of alkylene moieties and alicyclic moieties.

Preferably at least the majority of Ri is independently chosen from the group consisting of C1-C20 alkylene, C4-C20 alicyclic moieties and C6-C20 arylene moieties. Much preferred alkylene moieties areC2-C12 alkylene moieties. Much preferred arylene moieties are C6-C12 arylene moieties. Much preferred alicyclic moieties are C6-C12 alicyclic moieties.

In a preferred embodiment at least the majority of the R1's are independently chosen from the group consisting of adipic acid residues, terephthalic acid residues, isophthalic acid residues and naphthalic acid residues.

Preferably at least the majority of R2 and/or R3 are independently chosen from the group consisting ofC1-C20 alkylene andC4-C20 alicyclic moieties. Much preferred alkylene moieties areC2-C12 alkylene moieties. Much preferred alicyclic moieties areC6-C12 alicyclic moieties. The alkylene and alicyclic moieties may contain arylene groups.

Very suitable is a copolymer wherein at least the majority of the alkylene moieties are linear aikylene moieties, e. g. linearC1-C20 alkylene, preferably HnearC2-C12 alkylene. Preferably at least one chain segment Y is a diacid chain segment made of an acid end modified aliphatic, aromatic, or partially aromatic polymeric segment, wherein the polymeric segment is a polyolefin, polyether, polyester, polycarbonate, polysilane, polysiloxanes, polyacrylate or a copolymeric segment comprising moieties selected from the group consisting of olefin moieties, ether moieties, ester moieties, carbonate moieties, acrylate moieties, silane moieties, siloxanes moieties and styrene moieties. If these polymeric segments contain hydroxyl groups than these segments can be reacted with a diacid or diacid derivative to a diacid chain segment.

In an other preferred embodiment at least one chain segment Y is a diamine chain segment made of an amine end modified aliphatic, aromatic, or partially aromatic polymeric segment, wherein the polymeric segment is a polyolefin, polyether, polyester, polycarbonate, polysilane, polysiloxanes, polyacrylate or a copolymeric segment comprising moieties selected from the group consisting of olefin moieties, ether moieties, ester moieties, carbonate moieties, acrylate moieties, silane moieties, siloxanes moieties and styrene moieties.

One or more polymeric segments Y in a polymer prepared according to the process of the invention may comprise one or more polyethers. Suitable polyethers as polymeric segment Y include segments that comprise poly (tetramethyleneoxide) (PTMO), poly(propyleneoxide) (PPO), poly(ethyleneoxide) (PEO), poly(pentamethyleneoxide), or copolymers of any of these polymers. Suitable polyesters include aliphatic polyesters such as poly(hexylene adipate), poly(butylene adipate), polypropylene adipate), poly(ethylene adipate). Also segments comprising acrylic acid, acrylester, styrene, functionalized polystyrene, unsaturated polyols, functionalized polyolefin's like C36-diacid (Uniquema), C36-diol (Uniquema), this for hydroxyl, amine, ester or acid functionalized segments. Also maleic anhydride modified polybutylene, polyisoprene, natural rubber, polyethylene, poly (ethylene-butylene) copolymers, polyethylene copolymers, poly (ethylene-propylene) copolymer, EPDM, SBS and SEBS. Instead of maleic anhydride groups the segments might contain also other acid, anhydride, amine, and hydroxyl groups. In a preferred embodiment at least part of the Y segments are selected from the group consisting of polyvinylalcohol segments, poly(alkyleneoxide) segments (e. g. PTMO, PPO, PEO), aliphatic polyester segments, polysiloxanes segments, poly (ethylene-butylene) segments, C36 segments and acrylic acid polymer segments. In particular a copolymer comprising one or more of these types of segments has been found to combine a low glass transition temperature with a high melting temperature.

For applications wherein a "soft touch" is desired, a copolymer wherein Y at least consists of one or more segments selected from the group consisting of polyether-, aliphatic polyester-, polycarbonate-, polysiloxanes-, poly(ethylene-butylene) -, polybutylene-segments has been found to be particularly suitable.

A polymer prepared according to the process of the invention may comprise one or more chain segments Y that are extended with an ester, polyester, carbonate, polycarbonate, epoxy, poly (epoxy), imide, polyimide or the like. A polymer prepared according to the process of the invention may comprise in the Y segment polyfunctional units like tri and tetra units, leading to some degree of branching and cross-linking. With these units the compression set properties are improved.

Good results have been achieved with a polymer wherein Y is an extended flexible chain segment such as; polyethers extended with esters like terephthalic or isophthalic groups and or polyesters like poly(ethylene terephthalate) and poly(butylene terephthalate). Preferred flexible chain segments include poly(tetramethylene oxide), poly(propylene oxide), poly(ethylene oxide), poly(tetramethylene adipate), polycarbonate, poly(ethylene/butylene), poly(dimethylsiloxane), polycarbonate, polyolefin.

For example a polyether segment with hydroxyl end groups can react with a diacid or diacid derivatives to higher molecular weight segment and very good results have been obtained with a poly(tetramethyleneoxide) extended with terephthalic or isophthalic acid derivative to a higher molecular weight segment resulting in polymers with a very low modulus and excellent elastic properties like tensile set and compression set. This extending of the segments in Y might take place before, after or at the same time as the amide segments are coupled to the other segment.

The segments might be coupled to the amide segments by several types of units, like ester, polyester, carbonate, polycarbonate, epoxy, epoxy polymer, imide and polyimide. These Y segments with functional groups may be prepared first or can be formed during the polymerization process.

Very good results have been achieved with a polymer wherein at least the majority of the segments Y have a molecular weight in the range of 45-40,000 g/mol, preferably 200-20,000 g/mol. In a much preferred embodiment at least the majority of the segments Y have an molecular weight in the range of 300 to 20,000 g/mol. Very suitable is a copolymer wherein at least the majority of the segments Y have a molecular weight of at least 500 g/mol. Very good results have been achieved with a copolymer wherein at least the majority of the segments Y have a molecular weight of more than 4,000 g/mol. The size of a polymer prepared according to the process of the invention may-depending upon its intended use-be chosen within a wide range. For example the number average molecular weight (Mn) of the polymer may be in the range of 1 ,000 g/mol to 1 ,000, 000 g/mol. Preferably, Mn is approximately 2,000 g/mol to 100,000 g/mol. A copolymer prepared according to the process of the invention may in principle be prepared in any way. For example the Amide- (R-Amide-) n segments may be prepared in a condensation reaction, e. g. by reacting diacids with diamines, by reacting polyaminoacids, or by reacting aminoacids with either a diacid or diamine. In this way polyamide segments are formed wherein n is 3-6. Polymers are prepared with these polyamide segments and units that form Y segments in the polymer.

In a preferred embodiment the whole Amide- (R-Amide-)n segment is prepared first, and then a copolymer is formed with a compound providing segment Y. This gives the possibility to obtain a copolymer with a high uniformity of the length of the amide segments. For example a tetra-amide segment with ester end groups can be reacted with a Y segment containing hydroxyl end groups and extending terephthalic groups in the chain.

Good results have been achieved with a polymer wherein the amide segment is made from a diamine and a diacid and used in the polymerization reaction without first isolating the amide compound. For example a diamine can be reacted with an acid compound forming an amide which reacts with a compound Y. In the course of reaction amide segments of a suitable length, e. g. tetra-amides, are formed. Preferably a mixture of acid compounds is use for this reaction with different reactivity's. As diacid derivative several options are possible: e. g. monomethylester acid, dimethylester, monophenylester acid, methylphenylester, diphenylester, monomethylester monoacid chloride, diacid chloride and also dimethylester and water resulting in monomethylester acid. The advantage of this last route is that it can be a "one pot" synthesis. It is also possible to form the methylphenylester and diphenyl ester from terephthalic acid, monomethylester acid and/or dimethylester with diphenyl carbonate.

Examples of suitable diacids, diamines, respectively amino acids are HOOC-Ri-COOH, H2N-R2-NH2, respectively H2N-R3-COOH, wherein Ri, R2, respectively R3 are as identified above.

As a polymer prepared according to the process of the invention crystallizes fast from the melt it is very easily processable, particular by extrusion and injection molding. The markets for these materials are e. g. automotive (boots, safety hatches, seals, headlight housing), consumer (snow boards, ski shoes, springs, in-line skates), electrical/electronic (protective coverings, water seals) and industrial (low noise gears, pumps, conveyer belts). The polymer is also very suitable for overmoulding of another polymer part made of polyamide, polyester, polypropylene, polyacetal, polystyrene, polycarbonate, polyphenylene ether.

A polymer may also very suitably be employed in co-extrusion with one or other polymers, such as polyamides, polyesters, polyethylene, polypropylene, polyurethanes, polyureas, polyacetal, polycarbonate, polystyrene, polycarbonate, poly (phenylene ether), and/or copolymer and combinations thereof.

A polymer prepared according to the process of the invention is strongly orientable and may very suitably be used for manufacturing fibers with good properties, such as high elasticity, strong strain hardening, high fracture stress, high fracture strain and a high melting temperature. A fiber from a polymer prepared according to the process of the invention may be used in textiles (e. g. for the manufacture of garments where comfort and fit are desired: hosiery, swimsuits, aerobic/exercise wear, ski pants, golf jackets, disposable diaper, waist bands, bra straps and bra side panels). These fibers can also be used in compression garments: surgical hose, support hose, bicycle pants, foundation garments and in shaped garments like bra cups.

A very suitable copolymer for the manufacture of a fiber is a copolymer according to the invention, having a tensile set (TS300%) of less than 20 % (measured as is indicated above) and a melting temperature of more than150 ⁰C, preferably more than180 ⁰C. Such a polymer has been found to be very appropriately processable by melt spinning.

The copolymer might also contain an unmodified polymer Z, with which it is blended.

A polymer prepared according to the process of the invention may also very suitably be employed in breathable films, in membranes and in biocompatible materials. Particular polymers containing Y segments that consist mainly of polyethylene oxide (PEO) are very suitable for this as they combine a hydrophilic nature with good elastic properties.

The properties of the polymer prepared according to the process of the invention usually improve by increasing molecular weight. A side effect of higher molecular weight materials is a higher melt viscosity and a lower crystallization rate.

A low molecular weight material has a very low melt viscosity that is good for processability but poor for the elastic properties. It has now been found that if a low molecular weight polymer is made with less Y segments compared to amide segments, with as consequence that the majority of the end groups are amide groups, they have a low viscosity and surprisingly this combined with excellent elastic properties like compression set.

The invention further relates to a composite comprising a polymer according to the invention, preferably a polymer of which at least the majority of the amide segments are tetra-amides (i. e. wherein=3). Particular suitable are composites comprising a polymer prepared according to the process of the invention with reinforcing fillers like mica, kaolin, calcium carbonate, glass fiber, aramide fiber, carbon fiber and the like.

A polymer prepared according to the process of the invention may be employed as such or in a composition further comprising one or more fillers, fibers, colorants, oils, antioxidants and/or other additives typically employed in polymer materials.

A copolymer prepared according to the process of the invention may also be used in combination with an oil. Such a composition may for example be suitable for soft touch applications like: shavers, screwdrivers, tooth brushes.

The invention will now further be illustrated by the following examples, inh) of the polymers was determined at a concentration of 0.1dl/g in a 1 :

Experimental Segmented copolymers with bisester tetra-amide TXAXT and TXTXT rigid segments and an aliphatic polyether like poly(tetramethylene oxide) (PTMO) as a flexible segment were made in a polycondensation reaction. The T stands for a terephthalic unit, the X for a diamine species and the A for an adipic unit. The bisester tetra-amide segments were prepared prior to the polymer synthesis. The XAX and XTX compounds were synthesized from dimethyl adipate (A) or dimethyl terephthalate (T) and an excess of diamine (X) in the melt. The XAX and XTX compound were purified by recrystallization. The TXAXT and TXTXT compounds were synthesized from recrystallized XAX and XTX with an excess of methyl phenyl terephthalate (MPT) to obtain the products TXAXT and TXTXT having methyl ester end groups (TXAXT- dimethyl, TXTXT-dimethyl).

The purity of the XAX and XTX compounds was estimated by ¹H- NMR from the ratio R_p (integral CH₂ amide side (about 3.7 ppm) / integral CH₂ amine side (about 3.3 ppm)). Purity XAX = (2- R_p) x 100%. The uniformity of the T6A6T-dimethyl and T6T6T-dimethyl segments was estimated by ¹H-NMR from the ratio of aliphatic amide ester (3.6-3.7 ppm) over aromatic amide ester (3.7-3.8 ppm). The ratio R₁₁ (integral CH2 aliphatic amide ester side / integral CH2 aromatic amide ester side) is for T6T6T 1.0. The uniformity of T6A6T is approximated by (2-R_u)*100%. The inherent viscosity (η_inh) of the polymers was measured at a concentration of 0.1 g/dl in a mixture of phenol/1, 1,2, 2-tetrachloroethane (1 :1 molar ratio) at 25 ⁰C using a capillary Ubbelohde type 1 B (ASTM D446).

The amide content is calculated on the basis of the -Amide-(-R- Amide)_n- content in the -(Y-Amide-(R-Amide)_n-)_m-. Samples (70x9x2 mm) for the DMTA were prepared on an Arburg H manual injection moulding machine. The test samples were dried in vacuum at 50 ⁰C for 24 h before use. DMTA spectra were recorded with a Myrenne ATM3 torsion pendulum at a frequency of 1 Hz and 0.1% strain. The storage modulus G' and the loss modulus G" were measured as a function of temperature. The samples were cooled to -100 ⁰C and subsequently heated at a rate of 1 °C/min. The glass transition was determined as the peak in the loss modulus. The flow temperature (T_flOw) is defined as the temperature where the storage modulus reaches 1 MPa. The start of the rubbery plateau, the intercept of the tangents, is called the flex temperature (T_flex). The decrease in storage modulus of the rubbery plateau with increasing temperature is quantified by ΔG', which is calculated from:

ΔT is described as the temperature range: (T_fi_ow-50 ⁰C) - T_fleχ.

Samples for compression set were cut from injection moulded bars. The compression set was measured at room temperature according to ASTM 395 B standard. After 24 h the compression was released at room temperature. After relaxation for half an hour, the thickness of the samples was measured. The compression set was taken as the average of four measurements. The compression set is defined as:

Compression set = — x 100% (%)

Where: d₀ = thickness before compression (mm)

= thickness during compression (mm) d₂ = thickness after 0.5 h relaxation (mm)

Example 1

Preparation of diamine-diamide (6A6-diamine)

1 ,6-diaminohexane (500 g, 4.3 mol), was melted in a round bottomed flask and dimethyl adipate (53 g, 0.3 mol) was added. Sodium methoxide (6 ml of a 0.5 M solution in methanol) was added as a catalyst. The reaction was performed at 75 ⁰C for 16 h. After cooling the product was collected over a no. 4 glass filter, washed two times with diethyl ether and dried. The purity determined with NMR was 85% (Equation 1). The 6A6-diamine was recrystallized in hot 1 ,4-dioxane (16 g/l) at 100 ⁰C. After recrystallisation with a yield of 63% the purity was 98% and the T_m was 183 ⁰C as determined with DSC at a scan rate of 20 °C/min).

Preparation of T6A6T-dimethyl

T6A6T-dimethyl was made in a 2 L stirred round bottomed flask. A mixture of 6A6-diamine (34 g, 0.1 mol) and MPT (77 g, 0.3 mol) was dissolved in 1 I NMP and heated to 120 ⁰C. The reaction was kept at 120 ⁰C for 16 h. After cooling the reaction product was collected on a no 4 glass filter and washed with NMP, toluene and acetone consecutively. The T6A6T-dimethyl has a molecular weight of 666 g/mol, a uniformity >98% and a Tm of 255 ⁰C as determined with DSC at a scan rate of 20 °C/min.

Melt polymerization of PTMOinnn with T6A6T-ditnethyl The polymerization was carried out in a 250 ml stainless steel reactor with a nitrogen inlet and magnetic coupling stirrer. The reactor was charged with poly(tetramethylene oxide) with a molecular weight of 1000 g/mol (PTMO₁₀₀₀) (TERATHANE obtained from Dupont) (50 g, 0.05 mol), T6A6T-dimethyl (33.3 g, 0.05 mol), 1 wt% Irganox 1330 (based on PTMO) and catalyst solution (5 ml of 0.05 M Ti(i- OC₃H₇)₄ in m-xylene) under nitrogen flow. The initial reaction temperature was 260 ⁰C, 5 ^GC higher than the melting temperature of T6A6T-dimethyl. After 0.5 h the tetra- amide unit was molten and the reaction temperature was lowered to 250 ⁰C. This temperature was maintained for 4 h. The pressure was then carefully reduced to (P<20 mbar) and then further reduced to (P<0.3 mbar) for 1 h. Subsequently, the reactor was cooled slowly maintaining the low pressure. The so obtained copolymer (PTM0₁₀oo- T6A6T) with an amide content of 34.2 wt%, was only slightly colored and transparent, had an inherent viscosity of 2.2 dl/g, a glass transition of -58 °C, a flow temperature of 185 °C and a shear modulus at 25 ⁰C of 52 MPa. The compression set CS₂₅-_G was 9%.

Example 2

Polymers were prepared of PTMO and T6A6T-dimethyl with PTMO segment length of 650 to 2900 g/mol in the method described in example 1. The properties of these copolymers are summarized in table 1. All these copolymer were transparent and colorless to lightly yellow.

Table 1: Properties of melt synthesized PTMO-T6A6T

Amide Hlnh G' 25 'C T₈ Tflex ΔG¹ *10^"3 Tfiow CS 25 °C Color content

(%) (di/g) (Mpa) (⁰C) (⁰C) (⁰C-¹) CC) (%)

PTMO650-T6A6T 43.8 1.2 85 -46 10 5.6 195 20 Transparant, colorless

PTMO₁000-T6A6T 34.2 2.2 52 -58 -10 5.2 185 9 Transparant, colorless

PTMO1400-T6A6T 27.1 1.9 30 -65 0 4.0 180 11 Transparant, colorless

PTMO2000-T6A6T 21.1 1.3 18 -69 15 3.4 170 14 Transparant, colorless

PTM0₂₉oo-T6A6T 15.7 2.1 6 -71 30 3.9 150 14 Transparant, colorless

Comparative Example 3

Solution/melt polymerization (PTMOimn-T6A6T)

The polymerization was carried out in a 250 ml stainless steel reactor with a nitrogen inlet and magnetic coupling stirrer. The reactor was charged with PTMO₁OO₀ (50 g, 0.05 mol), T6A6T-dimethyl (33.3 g, 0.05 mol), 100 ml NMP, 1 wt% Irganox 1330 (based on PTMO) and catalyst solution (5 ml of 0.05 M Ti(i-OC₃H₇)₄ in m- xylene) under nitrogen flow. The stirred reaction mixture was heated to 180 ⁰C in 0.5 h and subsequently in 2 h to 250 ⁰C. This temperature was maintained for 2 h. Subsequently, the pressure was carefully reduced (P<20 mbar) to distil off the NMP and then further reduced (P<0.3 mbar) over 1 h. The reactor was cooled slowly, maintaining the low pressure. The so obtained copolymer (PTMO₁₀₀₀-T6A6T) with an amide content of 34.2 wt%, was brown colored and was transparent, had an inherent viscosity of 2.5 dl/g, glass transition of -70 ⁰C, a flow temperature of 185 ⁰C and a shear modulus at 25 °C of 51 MPa. The compression set CS₂₅»c was 14%. In a similar way were other PTMOx-T6A6T block copolymers prepared with PTMO length 650 to 2900 g/mol (Table 2). All these copolymers were transparent brown materials. Table 2: Properties of solution/melt synthesized PTMO-T6A6T

PTMO-tetra- Amide ηinh G' 25 "C Tg TflθX ΔG' Tfiow CS 25°C Color amide content (MPa) *10^"3 (%)

(%) (dl/g) CC) (⁰C) (°c-¹) (⁰C)

PTMO65₀-T6A6T 43.8 1.8 102 -45 35 5.0 200 17 Opaque, brownish

34.2 2.5 51 -60 -15 4.9 185 14 Transp, brownish T6A6T

PTMO1400- Transparant,

27.1 1.5 33 -67 0 3.9 180 14 T6A6T brownish

21.1 2.9 18 -70 10 2.9 180 9 Transp, brownish T6A6T

15.7 3.5 9 -70 20 1.8 175 7 Transp, brownish T6A6T

Example 4

Segmented copolymers of polyether and TXAXT-dimethyl or TXTXT- dimethyl were synthesized with PTMO segment length of 1000 g/mol. The length of the diamine X in the TXAXT-dimethyl and TXTXT-dimethyl was varied.. The melting temperatures of the used TXAXT-dimethyl and TXTXT-dimethyl compounds are given in Table 3. As example of the melt synthesis of these polyether-tetra-amide block copolymers the synthesis of PTMO_{1 OO}o-T8T8T is given.

Melt polymerization of PTMOinnn with T8T8T-di methyl

The polymerization setup was used as the same as described in example 1. The reactor was charged with PTMO₁₀₀₀ (50 g, 0.05 mol), and T8T8T- dimethyl (37.1 g, 0.05 mol), 1 wt% Irganox 1330 (based on PTMO) and catalyst solution (5 ml of 0.05 M Ti(i-OC₃H₇)₄ in m-xylene) under nitrogen flow. The initial reaction temperature was 280 (5-10 ⁰C higher than the melting temperature of the tetra-amide unit). After 0.5 h the T8T8T-dimethyl unit was molten and the reaction temperature was lowered 20 ⁰C. This temperature was maintained for 4 h. The pressure was then carefully reduced to (P<20 mbar) and then further reduced to (P<0.3 mbar) for 1 h. Subsequently, the reactor was cooled slowly maintaining the low pressure. The properties of the bisester tetra-amides and copolymers are summarised in Table 3. The copolymers (PTM0₁₀oo-tetra-amide), were transparent and slightly colored. The inherent viscosities of the melt synthesized copolymers were in the range of 1.2 to 2.2 dl/g. For the copolymers with a melting temperature of bisester tetra-amide segment of less than 260 ⁰C the inherent viscosities were higher than 2.0 dl/g.

Table 3: Properties of PTMO_{1 O}oo-tetra-amide synthesized in the melt

ΔH_m Melting Initial linh tetra-amide temperature Polym. melt

(J/g) Bisester tetra- temperature (dl/g) amide CC)

CC)

Comparative

PTMO₁₀₀₀-T6T6T 150 303 - - example

Comparative

PTMO₁₀₀₀-T4A4T 138 287 290 1.6 example

Comparative

PTMO₁₀₀₀-T8T8T 184 275 280 1.2 example

Example PTM0₁₀oo-T6A6T 161 255 260 2.2

Example PTMO₁₀₀₀-T10T1 OT 114 244 255 2.0

Comparative example 5

PTMO-iooo-tetra-amide copolymers were prepared by the solution/melt procedure as given in example 3 with PTMO_10Oo and TXAXT-dimethyl or TXTXT- dimethyl (Table 4). The solution/melt synthesized polymers of PTMO₁₀Oo with TXTXT and TXAXT have a brown color. Table 4: Properties of PTM0₁₀oo-tetra-amide synthesized by solution/melt route

Solution/melt polymerization color Hinh

(di/g)

PTMO₁₀₀₀-T6T6T Transparent / brown 2.2

PTM0₁₀oo-T8T8T Transparent / brown 1.6

PTMO_1Q00-T10T1 OT Transparent / brown 2.4

PTMO₁₀₀₀-T4A4T Transparent / brown 2.0

PTMO₁₀₀₀-T6A6T Transparent / brown 2.5

Claims

1. A process for the preparation of segmented copolymers having segments comprising 4 or more amide groups, comprising the steps of [i] mixing a component A having a segment comprising 4 or more amide groups and one or more reactive endgroups with a component B, having one or more endgroups that may react with the reactive endgroups of component A,

[ii] heating the mixture to a reaction temperature which is above the melting temperature of component A, whereby a reaction starts between component A and B, wherein the process is carried out in the absence of a solvent and wherein the component A has a melting temperature between 100 and 270 ⁰C.

2. The process according to claim 1 , wherein the reaction temperature of step [ii] is between 0 and 30 ⁰C higher then the melting temperature of component A.

3. The process according to claim 1 or 2, wherein the process comprises a reaction step [iii], wherein the reaction temperature is between 220 and 270 ⁰C.

4. Process according to anyone of the preceding claims, wherein the reactive endgroups of component A and/or B are selected from protons, hydroxy groups, amines, acids, ester groups and/or amide groups.

5. Process according to anyone of the preceding claims, wherein the uniformity of component A is > 70%.

6 A copolymer represented by formula (I)

-(-Y-Amide- (R-Amide-) n-) m- (I)

wherein each amide represents an N (H) C (O) or C (O) N (H) group, wherein each R is independently chosen from the group consisting of alkylene moieties, alicyclic moieties and arylene moieties, wherein n has an average value of at least 3, wherein m has a value of at least 1 , wherein Y represents a chain segment and wherein the copolymer has a L-value between 87 and 100 in the L*a*b colorspace.

7. The copolymer according to claim 6, wherein the copolymer has an 'a' value between -5 and +5 and a 'b'-value between -5 and +10 in the L*a*b colorspace.

8. The copolymer according to claim 6 or 7, wherein the L-value is between 90 and 100.

9. The copolymer according to anyone of claims 6-8, wherein 70-100 mol% of the Amide- (R-Amide-)" segments are uniform in length.

10. The copolymer according to anyone of claims 6-9, wherein the copolymer has a glass transition temperature below -30 ⁰C.

11. The copolymer according to anyone of claims 6-10, wherein the copolymer has a melting temperature higher than 150 ⁰C.