EP1438345A1

EP1438345A1 - Pure or mixed grafted thermosetting thermoplastic polyurethane, and thermoset polyurethane obtained after crosslinking

Info

Publication number: EP1438345A1
Application number: EP02796825A
Authority: EP
Inventors: Didier Lagneaux; Jean-Pierre Pascault; Michel Dumon; Françoise MECHIN
Original assignee: Noveon IP Holdings Corp
Current assignee: Lubrizol Advanced Materials Inc
Priority date: 2001-10-26
Filing date: 2002-10-24
Publication date: 2004-07-21
Also published as: FR2831542A1; CN1575307A; BR0213147A; NO20041963L; CA2464684A1; FR2831542B1; KR20040047970A; WO2003035711A1; US20040236035A1; JP2005506416A

Abstract

The invention concerns a pure or mixed grafted thermosetting thermoplastic polyurethane obtainable by direct grafting on a pure or mixed thermoplastic polyurethane, of a crosslinking agent selected in the group comprising diisocyanate trimers capable of initiating the crosslinking reaction at a temperature higher than 85 DEG C and blocked isocyanates, whereof the reactivation temperature is higher than 85 DEG C.

Description

THERMOSETTING THERMOPLASTIC POLYURETHANNE GRAFT, PURE OR MIXTURE, AND THERMODURCI POLYURETHANNE OBTAINED AFTER CROSSLINKING

The invention relates to a grafted thermosetting thermoplastic polyurethane (TPU), pure or mixed, which has the advantage of self-crosslinking in the presence of water or not, only under high temperature conditions (at least above 85 ° C. , advantageously greater than 90 ° C.) and in the absence of a catalyst. It also relates to pure polyurethane or theπnodurci mixture after self-crosslinking of said thermosetting TPU.

Different thermoplastic materials are used for the development of certain products such as hot fluid transport tubes, electric cables, solid wheels, seals, silent blocks, shoe soles, etc.

Thermoplastic polyurethanes are used in these different applications, in particular for their ease of implementation and their exceptional quality at room temperature, their flexibility and their mechanical resistance. However, these materials have the disadvantage of being not very resistant to heat so that the products obtained from these materials, depending on their use, have a short lifespan when used in an atmosphere with a temperature relatively high. On the contrary, thermosetting polyurethane resins, if they are actually intended to resist heat, remain very difficult to shape, so that their use is limited.

In view of these various problems, the objective has therefore been to develop polyurethanes having the physical characteristics and the ease of transformation of thermoplastic polyurethanes and the characteristics thermomechanics of thermosetting polyurethanes, and in particular their temperature resistance.

To do this, it was necessary to make the TPU crosslinkable so that they can be further processed, that is to say shaped, then only then, crosslinked to obtain a thermoset finished product.

To solve this problem, the Applicant has proposed in document FR-A-2 794 759 to graft hydrolyzed organosilanes on thermoplastic polyurethanes using a diisocyanate acting as a bridging agent between the polymer chain and the organosilane. This bridging agent also makes it possible to attach the aminosilane and prevents it from breaking the main chains of the polyurethane.

Even if this process makes it possible to make the TPU effectively crosslinkable by polycondensation of the silanoic groups, the Applicant has found that the crosslinking begins at ambient temperature and in the presence of moisture, thus prohibiting the storage of the TPU in a sustainable manner. In addition, the crosslinking phenomenon accelerates during drying (around 80 ° C) making the TPU unfit to be transformed. It is known in fact that this heating phase, before transformation, is essential because a tiny presence of water would cause crosslinking in the extruder at the time of transformation, leading to mechanical breakages of great importance. This process also has the disadvantage of requiring a high content and number of reagents, thereby creating an additional cost, which limits the volume of final applications. Finally, the Applicant has found that the TPU thus grafted could not be transformed at a temperature higher than approximately 180 ° C. insofar as, beyond this temperature, the bonds allowing the subsequent crosslinking created were quickly broken.

In other words, the objective which the invention proposes to solve is to provide a TPU having the following characteristics: - inability to self-crosslink in the presence of water at a temperature below at least 85 ° C, that is to say at a temperature of at least 5 ° C, advantageously 10 ° C above the drying temperature (approximately 80 ° C) of TPU grafted before transfoimation, - reduced number of constituents,

- possible transformation of the grafted TPU before crosslinking at a temperature above 180 ° C without destruction of the bonds allowing the crosslinking created in the grafted TPU.

To do this, the Applicant sought to graft directly on the TPU a diisocyanate (for example MDI), in the absence of silane. The reaction rates of diisocyanates with thermoplastic polyurethanes in reactors of the internal or external mixer type were then studied. It has been found that the grafting reaction of one of the two functions (NCO) of the diisocyanate was very rapid under pressure and at temperature, in the absence of water. The function (NCO) remaining free became less reactive. Concretely, a thermoplastic polyurethane sees its MVR (MELT VOLUME RATE) reduced by 2 after its grafting with diisocyanate. The grafted TPU then becomes very sensitive to water due to the presence of the free (NCO) function. This material in the form of granules cannot be stored for a long time, cannot be easily handled by the final transformer because it cannot be transported by suction and wait for its implementation in the open air, without being dried at the last moment as all commercially available thermoplastic polyurethanes. The final drying crosslinks the polyurethane in its granulated form and does not allow its thermoplastic transformation. As already said, it is especially important not to transform the grafted polyurethane diisocyanate without drying it because a tiny presence of water would cause crosslinking, which would lead to mechanical breakages of great importance during the transformation.

The grafted TPU proposed by the invention solves all of these problems. More specifically, the invention relates to a thermosetting thermoplastic polyurethane grafted, pure or as a mixture, capable of being obtained by direct grafting onto a pure thermoplastic polyurethane or as a mixture, of a crosslinking agent chosen from the group comprising trimers of suitable diisocyanates. initiating the crosslinking reaction at a temperature above 85 ° C and blocked isocyanates, solid or liquid, whose release point is above 85 ° C

In the following description and in the claims, “pure or mixed TPU” means a TPU alone or in mixture with at least one thermoplastic polymer chosen from the group comprising, without limitation, the

PP (polypropylene), PET (polyethylene terephthalate), POM

(polyoxymethylene), PBT (polybutylene terephthalate), HDPE (high density polyethylene), PS (atactic, isotactic and syndiotactic polystyrene), ABS (acrylonitrile / butadiene / styrene), PMMA (polymethyl methacrylate), PC

(polycarbonate), PVC (polyvinyl chloride), PEEK (polyether ether ketone), PPE (polyphenylene ether), PSU (polysulfone), aliphatic polyketone, their ho o-, co- and terpolymers. PE (polyethylene), PP

(polypropylene) metallocene, SBS (styrene butadiene styrene), SEBS (styrene ethylene butadiene styrene), COPE (copolyester block ester), EPDM

(ethylene propylene diene), their homo-, co- and terpolymers.

Of course, the TPU / thermoplastic polymer ratio will vary depending on the desired mechanical characteristics of the final mixture, in practice between 100/00 and 40/60, advantageously 70/30.

Such a thermosetting polyurethane is new with regard to the state of the art known to the Applicant, not only by its structure (limited number of constituents and specific crosslinking agent), but also by its behavior. The Applicant has in fact found that, quite surprisingly, the selection of the crosslinking agent, in the absence of silane, avoids the triggering of a crosslinking phenomenon at room temperature despite the presence of water and it was necessary, to initiate crosslinking, to increase the temperature to around at least 85 ° C, or up to a temperature above the drying temperature (80 ° C), in the absence of a catalyst. In practice, the crosslinking is carried out at a temperature above 100 ° C, between 110 and 130 ° C or more, depending on the release temperature of the diisocyanate, for 2 hours, after an initial moisture recovery of the polymer for 24 hours. At room temperature, it is possible to crosslink the thermosetting TPU of the invention, but only in the presence of a catalyst of the tin or bismuth type and in several days. In other words, the grafted thermoplastic polyurethane of the invention does not react or very little with water at temperatures below 85 ° C, advantageously 100 ° C, which allows it to be stored in the open air in standard poly bags. In addition, this allows the final processor to handle the grafted product without special precautions, respecting only the usual precautions of standard thermoplastic polyurethanes. As already said, it is thus possible, before crosslinking, to dry the polyurethane for at least 2 hours, advantageously 6 hours, without the grafted TPU starting to crosslink. In addition, the Applicant has found that the viscosity of the thermoplastic polyurethane, after grafting, was only reduced by a factor of 1.5 instead of 2 when the polyurethane is grafted with a diisocyanate, which makes it possible to widen the working range. In addition, during the final transformation, the MVR of the material is further reduced by a factor of 2, which improves the rheology of the polymer in the extrudeυse and calibrators, and reduces the formation of rotassures during injection into molds. Ultimately, it appears that the grafted polyurethane has a behavior closer to that of polyethylenes than standard thermoplastic polyurethanes. Finally, the Applicant has observed that the crosslinking bonds have a much higher temperature resistance than the bonds obtained with the diisocyanates used alone or in the presence of silanes. This characteristic makes it possible, in the event of a mixture of TPU with other polymers, not to break the crosslinking bonds, and therefore not to lose the mechanical, thermal and chemical characteristics of the mixture during final processing, at elevated temperatures above 180 ° C.

According to a first characteristic of the invention, the crosslinking agent is a diisocyanate trimer or a blocked isocyanate, the basic molecules of which are each chosen from the group comprising FIPDI (5-isocyanato-1 (isocyanatomethyl) -1,3, 3-trimethyicycioexane), HDI (1,6-diisocyanatoexane), TDI (1-3 diisocyanatomethylbenzene), 2,4'-MDI (1 isocyanato-2 (4-isocyanatophenyl) methyl-benzene), 4.4 'MDI (1,1-methylene bis (4-isocyanatobenzene)), 2,4-TDI (2,4 diisocyanato-1-methylbenzene) and PPDI (1,4-diisocyanatobenzene), Hj ₂ MDI (1, 1 -m ethylene bis (4-isocyanatocyclohexane)), CHDI (trans-1,4-diisocyanatocyclohexane), TMDI (1,6-diisocyanato-2,2,4 (or 2 ₃ 4,4) -trimethyllιexane), -TMXDI (1,3-bis (1-isocyanato-1-methylethylbenzene), p-TMXDI (1,4-bis (1-isocyanato-1-methylethylbenzene), NDI (1,5-diisocyanatonaphthalene), Polymeric MDI (isocyanic acid, polyethylene polyphenylene ester), Desmodur R (1,1 ' , 1 "- ethyllidynetris (4-isocyanatobenzene)) _; Desmodur RI (4-isocyanatophenol phosphorothioate (3: 1) ester).

In the case of blocked isocyanates, which can be dimers, trimers, etc., the blocking molecule is any molecule usually used (caprolactam, oxime, etc.) and perfectly known to those skilled in the art, in particular molecules. described in the publications: .Wicks Prog. Org. Coat. 9, p3, 1981 and L.TLPhai et al Makromol. Chem. 186, 1189, 1984.

According to another characteristic, the crosslinking agent represents between 0.5 and 20% by mass of the grafted polyurethane, alone or as a mixture.

In a preferred embodiment, the crosslinking agent is a trimer of IPDI and represents between 1 and 6% by mass of the polyurethane grafted alone or as a mixture. In practice, the grafted TPU of the invention is in the form of granules which can be stored in the state and subsequently transformed directly by the transformer by extrusion, calendering, injection, etc., and as already said, at temperatures high above 180 ° C due to the choice of crosslinking agent.

In another embodiment, the TPU is grafted then transformed directly continuously so as to obtain profiles of determined shape.

The invention also relates to the process for manufacturing the grafted polyurethane previously described, which consists in reacting, at a temperature of at least 85 ° C., a thermoplastic polyurethane, pure or in mixture, with one of the crosslinking agents previously described, advantageously a trimer of IPDI, then recovering the grafted thermosetting thermoplastic polyurethane obtained.

The selection of the aforementioned crosslinking agents, because of their structure, makes it possible to slow down the grafting reaction and indeed to avoid the complete crosslinking of the TPU during the manufacture of the grafted polymer at a temperature above 85 ° C.

The invention also relates to the thermoset polyurethane capable of being obtained after self-crosslinking of the thermosetting thermoplastic polyurethane graft previously described.

The invention and the advantages which result therefrom will emerge more clearly from the following exemplary embodiments. Example 1

Subjects:

- NONEON polyurethane: Estane 58447 ester type,

Hardness 90 Shore A,

Fusion Kofler around 185 ° C

- Trimer of DEGUSSA's IPDI: Vestanat Tl 890/100

Material 58447 witness: viscosity measured on melt indexer at 210 ° C under 8.16 kg = 40.

Material 58447 + 4 pcr of Vestanat T1890 / 100 extradited at 185 ° C on a single-screw 40 L 40 diameter extender at 56 rpm: viscosity measured on melt indexer at 210 ° C under 8.16 kg = 30.

Material 58447 + 4 pcr of Vestanat T1890 / 100 extradited at 185 ° C on a single-screw 40 L 40 diameter extender at 56 rpm, then re-extruded at 200 ° C on the same extruder: viscosity measured on melt indexer at 210 ° C under 8.16 g = 15.

Material 58447 + 4 pcr of Vestanat Tl 890/100 extradited 2 times, then put under heating press at 200 ° C for 10 minutes under 11 tonnes of pressure to obtain a test piece of 100 mm x 100 mm x 2 mm:

the viscosity of the material constituting the test piece is no longer measurable by the indexing melt,

- matter no longer dissolves in THF,

- the Kofler melting point goes from 185 ° C for the controls to 240 ° C for the material of the test piece,

- the value of the "compression set" at 70 ° C for 24 hours goes from 65% for the control to 25% for the test piece. Example 2

Subjects:

- NOVEON polyurethane: Estane 58315 ether type, Hardness 85 Shore A, Kofler Fusion around 150 ° C

Trimer of DEGUSSA's IPDI: Vestanat Tl 890/100

A mixture of 58315 with 4 pcr of Vestanat was carried out in a single screw extruder of the same type as that of Example 1, to obtain granules of 58315 grafted. After storage for one month, the grafted granule was dried in a ventilated oven at 80 ° C for two hours, then transformed on a calender at 190 ° C to obtain a sheet 1 millimeter thick. The same calendering operation was carried out with the control 58315.

In each of the two sheets, test pieces were cut to carry out a "hot set test" specific to the cable manufacturer. In an oven at 200 ° C, the material is subjected to a stress of 0.2 MPA. The test piece broke before two minutes. The crosslinked test piece has passed the 15-minute limit.

Example 3

Subjects:

- NOVEON Estane 58277 polyurethane ester type. Hardness 95 Shore A, Fusion Kofler about 150 ° C

- SBS from ASAHI Tufprene A, Hardness 88 Shore A Fusion 120 ° C

MDI from BAYER Desmodur 44 M

Trimer of the IPG of DEGUSSA Vestanat Tl 890/100

Mixing carried out 3 times on an extruder identical to the previous examples. Then manufacture of 2 mm thick test pieces in a heating press at 200 ° C for 11 minutes. 58277; 70% compounding 1: 150 ° C

Fusion Kofler compounding 2: 150 ° C

Tufprene A 30% compounding 3: 150 ° C

70% compounding 1,220 ° C

30% Fusion Kofler compounding 2 220 ° C

3 pcr compounding 3 220 ° C

58277: - | 70% compounding 1,200 ° C

Tufprene A> 30% Fusion Kofler compounding 2 180 ° C

^: MDI 3 pcr compounding 3 160 ° C

Claims

1 / Thermosetting thermoplastic polyurethane grafted, pure or in mixture, capable of being obtained by direct grafting on a pure ihermoplastic polyurethane or in mixture, of a crosslinking agent chosen from the group comprising diisocyanate trimers capable of initiating the crosslinking reaction at a temperature above 85 ° C and blocked isocyanates, solid or liquid, whose release point is above 85 ° C.

2 / Polyurethane according to claim 1, characterized in that the crosslinking agent is a diisocyanate trimer or a blocked isocyanate, the basic molecules of which are each chosen from the group comprising IPDI (5-isocyanato-1 (isocyanatomethyl) -1,3,3-trimethylcycloexane), HDI (1,6-diisocyanatoexane), TDI (1-3 diisocyanatomethylbenzene), 2,4'-MDI (1 isocyanato-2 (4-isocyanatophenyl) methyl-benzene) , 4.4 'MDI (1,1-methylene bis (4-isocyanatobenzene)), 2,4-TDI (2,4 diisocyanato-1-methylbenzene) and PPDI (1,4-diisocyanatobenzene), H _{] 2} MDI (1, 1 -methylene bis (4-isocyanatocyclohexane)), CHDI (trans-1,4-diisocyanatocyclohexane), TMDI (1,6-diisocyanato-2,2,4 (or 2,4,4 ) -trimethylhexane), m-TMXDI (1,3-bis (1-isocyanato-1-methylethylbenzene), p-TMXDI (1,4-bis (1-isocyanato-1-methylethylbenzene), NDI (1, 5-diisocyanatonaphthalene), polymeric MDI (isocyanic acid, polymeethylene polyphenylene ester), Desmod ur R (1,1 ', 1 - methyllidynetris (4-isocyanatobenzene)), Desmodur RI (4-isocyanatophenol phosphorothioate (3: 1) ester). 3 / Polyurethane according to one of the preceding claims, characterized in that the crosslinking agent represents between 0.5 and 20% by mass of polyurethane grafted alone or as a mixture.

4 / Polyurethane according to claim 2, characterized in that the crosslinking agent is a trimer of IPDI and represents between 1 and 6% by mass of the grafted polyurethane, alone or as a mixture.

5 / Polyurethane according to claim 1, characterized in that the TPU is mixed with a thermoplastic polymer chosen from the group comprising, without limitation, PP (polypropylene), PET (polyethylene terephthalate), POM (polyoxymethylene) , PBT (polybutylene terephthalate), HDPE (high density polyethylene), PS (atactic, isotactic and syndiotactic polystyrene), ABS (acrylonitrile / butadiene / styrene), PMMA (polymethyl methacrylate), PC (polycarbonate ), PVC (polyvinyl chloride), PËEK (polyether ether ketone), PPE (polyphenylene ether), PSU (polysulfone), aliphatic polyketone, their homo-, co- and terpolymers. PE (polyethylene), PP (polypropylene) metallocene, SBS (styrene butadiene styrene), SEBS (styrene ethylene butadiene styrene), COPE (copolyester block ester), EPDM (ethylene propylene diene), their homo- , co- and terpolymers.

6 / Polyurethane according to one of the preceding claims, characterized in that it is in the form of granules.

7 / A method of manufacturing the grafted polyurethane which is the subject of one of claims 1 to 6, characterized in that it consists in reacting, at a temperature of at least 85 ° C, the pure TPU or in mixture with the crosslinking agent then recovering the grafted thermosetting thermoplastic polyurethane obtained.

8 / Thermoset polyurethane capable of being obtained after self-crosslinking of the polyurethane which is the subject of one of claims 1 to 6.