MXPA97002981A - Perfluoropolimeros love - Google Patents

Abstract

The use of amorphous perfluoropolymers based on TTD dioxol homopolymers or their amorphous copolymers to prepare solutions in fluorine-containing solvents, to obtain solutions for coatings, in which the TTD has the formula: CF = C-ORf -OO- CX1X2 in which RF is a perfluoroalkyl radical with 1-5 carbon atoms, linear or branched when possible, X1 and X2 are equal to or different from one another being F or CF3, the amount of TTD is on the scale of 40 to 100 mol%

Description

PERF UQRQPOLIIIERQS AMORFOS II DESCRIPTIVE The present invention relates to amorphous polymers based on fluorine-containing monomers usable in particular for coatings. More speci fi cally refers to furnace polymers or copolymers having solubility in fluorine-containing solvents, which are also preferably non-aggressive to ozone (low ODP) and which also have a low global warming impact (GUP) of at least 15% by weight, most preferably greater than 20% by weight, combined with good mechanical properties. It is well known that in coating applications it is desirable that the polymer concentration in the solvent be as high as possible. This leads to operate with less amount of solvent and therefore with reduced problems of recovery and environmental impact. Moreover, the solvents that will be used should not be toxic and should preferably have the characteristics indicated above, since the laws of several countries have prohibited the use of many solvents used so far, due to problems of impact on the layer of ozone. As examples of solvents that can no longer be used because of their impact on the ozone layer, we can mention solven + es that contain chlorine, chlorofluorocarbons (CFCs). In particular CFC 113 (CClaF-CClFa, normally used as a solvent for preparing solutions for coatings can not be used anymore) More particularly, the invention relates to perfluoropolymers which, as is well known, can be crystalline or amorphous. Crystalline polymers are characterized by high thermal stability and high chemical resistance, however, these polymers are insoluble in any solvent at room temperature, therefore they can not be used to prepare solutions for coatings. They are characterized by low optical properties, since the presence of cpstalites gives rise to the dispersion of light.The amorphous perfluorocarbons can be subdivided into two classes: those that have a transition temperature Tg lower than the ambient temperature and those that have a temperature Tg greater than the ambient temperature. interlacing to confer to the material the required mechanical properties that a coating must have. The latter are in the vitreous state up to the Tg of the material and therefore have mechanical properties up to the Tg of the material without the need for any interlacing. The present invention relates to this latter group of amorphous perfluoropolymers.

Amorphous perfluoropolymers of this kind are known in the art, see for example the US patent. No. 3,865,845 in which the opium oxides of a specific dioxole, i.e.? Erfluoro-2,2-d? Met? L? L, 3-d? Oxol (PDD) and PDD copolymers with -tetrafluoroethylene (TFE) are described . In this patent, PDD homopolymers and crystalline copolymers having a melting point of 255 ° C are exemplified. Crystalline copolymers have been obtained using lower amounts < 1e 12% molar of PDD. It is well known, according to the teaching of the patent, that the copolymers between PDD / TFE with any ratio of the two monomers can be prepared. In the patent it is mentioned that the examples are given only for illustrative purposes, but the skilled person is able to carry out several other examples to prepare the copolyes with various PDD / TFE ratios. In particular, the skilled person can prepare crystalline and amorphous copolymers also with the absence of residual stability to obtain a product with good optical properties. In fact, in the description it is mentioned that the homopolymers and copolymers of the invention can be used to cast in the form of films, that is to say to prepare solutions for coating. Solubility in solvents non-aggressive to ozone, for example FLUORINE T FC 75, results ba and much lower than the limits indicated above, as reported in patent UO 95/07306 described below.

In EP 73087, the PDD / TFE copolymers are described in which the TFE can be in the range from 1 to 99% by weight. In practice, this patent characterizes the copolymers already described in the previous patent. It is mentioned that if the amount of PDD is less than 11 mol%, the crystalline copolymers are obtained, moreover, different Tg are obtained depending on the amount of PDD. For example, with 11.2% molar PDD there is a Tg of 57 ° C, while with 56.9% there is a Tg of 119 ° C. As for the solubility, the concentrations made for the previous patent are valid. Additional characterization data are given in EP 645406 and it is mentioned that the PDD amorphous copolymers are soluble in FLUORINERTR FC 75 produced by 3M Company (? Erfluoro (n-but? L-tetrahydrofuran)), because the copolymers are particularly suitable for reverses. A 5% solution of a copolymer with a PDD content of 72 mol% is exemplified. Amorphous copolymers having a combination of optimum properties have a PDD content in the range of 65 to 99 mole%. Also in this case the solubilities in the exemplified solvent are very low. From USP 4,594,399, the TFE polymer and copolymer ovens are known with another specific dioxole in which the carbon attached to the oxygen atoms, instead of two per-chloroalkyl groups of C -C ", consider the case in which q? One of these groups is F or Cl. It is mentioned in the patent that said opolimeroe and copolymers can be used to prepare solutions for coatings. Solubility values in the aforementioned solvents are not given. Moreover, it is known from the patent EP 80187? Dioxol (PD) having the two carbon valencies linked to oxygen saturated with two fluorine atoms. The crystalline and amorphous copolymers of this specific dioxol are described, and the latter are obtained when the amount of PD is greater than 12 mol%. Coatings with FC 75 solutions, which have imipene concentrations of about 3% by weight, are described. From EP 95077 the fl orodioxoles are known in which at least one hydrogen or chlorine atom is present in the carbon in the double bond. It is mentioned in the description that the amorphous copolymers are soluble in FC 75 and therefore usable for coatings. The experimental solubility data are not reported. UO patent 95/07306 describes functional fluoropolymers, which are obtained by the use of functional monomers introduced in homopolymers or copolymers based on PDD. The amounts of the functional monomer are preferably in the range of 0.5 to 5 mol%. This functional inonomer has the purpose of increasing the solubility, since the amorphous PDD copolymers, in particular with TFE, have low solubility. In particular the solubility is 2% by weight when the PDD is present in amounts of approximately 95 mol%; if the amount of PDD is 65 mol% the solubility in FC 75 is 10% by weight. With the addition of the functional monomer, the solubility is slightly increased. The Applicant has surprisingly and unexpectedly discovered a particular and specific class of amorphous perfluoropolymers based on a particular and specific dioxole which has high solubility in solvents as defined above, for example FC 75, without using additional functional monomers. An object of the present invention is the use of homopolymers of TTD dioxol or its amorphous copolymers to prepare solutions in fluorine-containing solvents, preferably also non-aggressive to the ozone layer and also with a low impact of GUP, in order to obtain solutions for coatings, in which the TTD has the formula: C \ / CX Xa¡ in which R is a perfluoroalkyl radical with 1-5 carbon atoms, linear or branched when possible; X and X2 are equal to or different from each other with F or CFa; the amount of TTD is on the scale of 40 to 100% molar; the other coronary, in the case of the copolymers, is chosen from one or more of the following: tetraf.1 uoroetiene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropene (HFP), perfl? oroalkylvinyl ether (PfiVE) of formula CFa = CFOR 'in which R' F is a perfluoroalkyl radical of 1 to 3 carbon atoms. Other co -omers that can be used are the PDX and PD dioxoles indicated above. The solubility in the aforementioned solvents of the TTD polymers or their amorphous copolymers with the cornonomers indicated above is found to be greater than 15% by weight, in particular greater than 20% by weight, and can also reach values of 60% by weight or more . Copolymers can be prepared with several Tg by varying the percentage of TTD. The intrinsic viscosities of the polymers are generally in the range of 20 to 200 cc / g, preferably 40-100 cc / g, measured for example in FLUORINERT * FC 75 (per luoro (n-butyl-tetrahydrofuran)) at 25 ° C. ° C. Preferred copolymers according to the present invention are the copolymers of TTD with tetra fluoroenene. The other comonomers when present are generally in amounts between 0.1 mol% and 20 mol%, preferably less than 10 mol%. The comonomers are generally chosen so as to preferably give a Tg greater than 100 ° C. Preferably the amount of TTD is in the range of 50 to 95 mol%. The preferred TTD is that in which Rp- is equal to CFa and Xi and X2 are equal to F. In this case among the other co-operators, you can also use the TTD, in the ue Xa. and Xa are CF3, or at least one of the two is CFa. The TTD dioxols and the corresponding homopolymers and copolymers according to the present invention are prepared and obtained in accordance with USP 5,498,682. The useful solvents which have the above characteristics are those solvents, optionally containing ethereal oxygen in the ring or heteroatoms such as nitrogen; perfluoropolyethers which contain perfluorooxyalkylenic units and with final groups, optionally the hydrogen-containing terminals, such as -OCFs-H, -0CF (CFa) H, -OCFaCFaH and -0CF (CF2H) CFa. The boiling points of perfluoropolyether products are generally in the range of 60 to 300 ° C, preferably 80 to 160 ° C. As solvents there may be mentioned in particular the? Erfluoro (n-but? I-tetrahydrofuran), perfluoropolyethers with perfluorinated end groups, for example GftLDEN D80 marketed by RU? IMONT, having boiling temperatures of 82 ° C and molecular weight average of 390, perfluoropolyethers in which at least a final perfluorinated group contains a hydrogen atom. Perfolyopolyethers are polymers containing the following randomly distributed units along the chosen chain of: (C = .F. D), (CaF ^ .O), (CFXO) where X is equal to F or CFa , (CR R2CF? CFaO) where Rx is equal to or different from Rs »is H, F, perfl? Oroalkyl of C -Ca. In particular, the following perfluoropolyethers can be mentioned: a) -0 (CaF < sO) m, (CFXO) n, - wherein the unit (CaFA0) and (CFXO) are perfluorooxyalkénic units distributed randomly along the chain; m 'and n' are integers to give products with boiling points generally from 60 ° to 300 ° C, and m '/ n' are comprised from 5 to 40, when n 'is different from 0; X is equal to F or CFa; n 'can also be 0; b) where p ', q' and t 'are integers to give products with a boiling point indicated in a), p' / q 'are in the scale of 5 to 0.3, preferably of 2.7-0.5; t 'can be 0 and q' / íq '+ p' + t ') less than or equal to 1/10 and the relation t' / p 'is from 0.2 to 6; c) - (CRxRaCFaCFsjOn- where Rx and R2 have the meaning indicated above, and n is an integer to give products with melting point indicated in a); the final groups are chosen from -CF3, -C2Fa, ~ CaF7, -CF2H and -CFHCFa. The mentioned fluropolyethers are obtained by methods well known in the art, for example see the patents of E.U.fl. Nos. 3,665,041, 2,242,218, 3,715,378, 4,954,271 and European patents Nos. EP 239,123, EP 148,482 as well as international patent application UP 95/26218. The hydrogen-containing terminals of the perforopolyethers can be prepared, for example, in accordance with EP 695,775. Perfluoropolyethers or hydro-luo-polyethers (perfluoropolyethers with perfluorinated end groups containing at least one hydrogen atom) are formed by a mixture of components having different molecular weights with boiling points included in the aforementioned scales. The solutions of the polymer or copolymer furnaces of the present invention in perfluorinated or perfluoropolyether solvents can be used for coatings, for example by centrifugal coating / casting, injection, spray and brush coating. Very thin films are obtained by the centrifugal coating. As already mentioned above, the polymers of the present invention show a combination of a high solubility in the aforementioned solvents and good mechanical properties, in particular stress to relaxation and elongation at break. The solubility limits according to the present invention have been determined by the method indicated hereinafter. Table 2 reports the maximum solubility values measured in several solvents for different amorphous polymers, obtained by copolyzing TFE with TDD.

By maximum solubility it is intended to say the maximum concentration at which the polymer-solvent solution no longer flows when the container is turned over. This measurement is expressed with a weight ratio considering the polymer weight as a percentage of the weight of the solvent. The maximum solubility is measured using the following procedure: In a 50 ml glass flask equipped with a stirrer, the polymer powder and the solvent are introduced. The polymer and the solvent introduced are exactly known, since they are weighed in an analytical balance that has an accuracy of up to the third decimal figure. Once the components are introduced, the flask is closed and the agitator is ignited by means of a mechanical ignition engine. The agitation is comprised between 10 and 20 rprn. The system is stirred at room temperature until complete solubilization of the powder is observed. When the powder is completely dissolved, stirring is stopped and the container is flipped. If flowability is noted, an exactly known amount of polymer is again introduced and the stirring is repeated until full solubilization is observed. At this point the agitation is stopped again and the flow ability of the solution is evaluated again. If flowability still exists, it is operated as previously indicated, unless the last value is considered to be the maximum solubility of the polymer in the solvent.

The solvents used in the examples are the following: - FLUORINERT * FC 75 perfluoroin-butyltetrahydrofuran), marketed by 3M Company, boiling temperature (T »to) of 103 ° C, molecular weight (MW) of 416; - GALDEN® D80 (perfluoropolyether), marketed by flueinont, and with a Tβ of 82 ° C, average molecular weight (MW) of 390 (perfluoropolyethereal structure a) with final perf1uroa1k1.l groups); - GflLDEN H (perfluorpolieter of the type GfiLDEN BOD in which a final group is perfluorinated and the other is -CFHCFa or -CFssH), the content of H is approximately 120 ppm, the T & t > of 110 ° C, the average molecular weight (MW) of 500 (perfluoropolyethereal structure a)). The dioxol used in the examples is TTD 2,2,4-trifluoro-5-trifluoromethoxy-l, 3-dioxol with the formula indicated above. The following examples are given for illustrative purposes only and are not limiting of the present invention. EXAMPLE 1 A vertical RISI 316 steel autoclave of 5 liters equipped with an agitator that works at 650 rpm is used. After the vacuum, 2960 cc of demineralized water and an aqueous perfluoropolyether mixture prepared in accordance with Example 1 of the U.S. Patent. No. 4,864,006, are introduced in sequence into the autoclave in an amount such that 6.6 g of microemulsion / 1 of Hs.0. The reactor is brought to the temperature of 75 ° C and then 86.3 g of TTD / 1 Ha0 (initial charge of TTD) are introduced and the pressure of 17 bar absolute with TFE is reached. After 40 cc of an initiator solution (potassium persulfate) with a concentration of 0.925 mol / 1 H ^ O are introduced. The reaction pressure is restored to the initial value after each decrease of 0.5 bar with a semicontinuous feed of liquid TTD and gaseous TFE, in the ratio of 2.5 TTD / TFE by weight between the two rnonomers. 1036 g of TTD (excluding the initial load) are fed in total. After 450 minutes the reaction is stopped, a latex characterized by a solids content of approximately 27% by weight is discharged from the reactor. The latex is coagulated with HNOa at a concentration of 65% by weight and dried in an oven at 95 ° C for 40 hours. The white powder thus obtained is used for all chemical-physical measurements: glass transition temperature (Tg), intrinsic viscosity, NMR and solubility measurements. The same powder is extruded in a BRABENDER extruder, fixing a temperature in the melted product of 250 ° C. The obtained granules are used for the compression molding of the plates used for the mechanical properties. In table 1 chemical-physical and mechanical properties are reported; in table 2 the solubility data in the aforementioned solvents are reported.

EXAMPLES Iñ AND 2A (COMPARATIONS? Example 1 is compared with literature data referring to TEFLON AF 1600 (eg IA) and 2400 (eg 2A) reported in Macromolecular Syrnp. 82, 61-65 (1994) for the mechanical and rheological properties (see Table 1); and with the solubility data reported in TEFLON AF - Technical Information - Properties of Amorphous Flo? Ropolyrners Based on 2,2-Bistrifluoromethyl-4,5-Difluoro-1, 3 ~ Dioxole, U.H. Buck and P.R. Resnick, presented at the 183rd Meeting of the Electrochemical Society, Honolulu, HI, May 17, 1993, pages 1-11 (see table 2). The dioxol used in these comparative examples is 2.2 per luoroethyl, 4,5-difl? Oro-l, 3-dioxol of PDD.

EXAMPLE 2 The procedure is the same as in Example 1 except for the following modifications: the amount of TTD initially introduced turns out to be 65.3 g / 1 water, the polymerization pressure reached with the TFE results in 14 bar absolute, the reaction pressure ( 14 bar absolute) is reestablished after each decrease of 0.5 bar by the semi-continuous feeding of liquid TTD and gaseous TFE in the weight ratio TTD / TFE = 2.58. 493 g of liquid TTD (excluding the initial charge) are fed in total. After 333 minutes the reaction is stopped and a latex with a solids content of 1.1% is discharged from the reactor. The latex is coagulated with 65% nitric acid and dried in an oven at 95 ° C for 40 hours. The chemical-physical characteristics of the polymer are reported in table 2.

EXAMPLE 3 It is operated as in example 1 with the following modifications: the amount of water introduced turns out to be 3276 cc, the initial TTD amount turns out to be 299 g (TTD) / l (Ha0), the polymerization pressure reached with TFE is 14 bar absolute, the amount of initiator introduced turns out to be 24 ce. The initiator solution has the same molar concentration as that of Example 1. the reaction pressure is kept constant throughout the synthesis by means of the liquid, liquid TTD and gaseous TFE feed, in the TTD / TFE ratio = 12 by weight between the two monomers. 960 g of liquid TTD (initial charge excluded) are fed in total. After 170 minutes the reaction stops, the degree of solids achieved turns out to be 7%. The polymer is coagulated with 65% HNOa and oven-dried at 100 ° C for 24 hours.

EXAMPLE 4 The procedure is the same as in Example 1, except for the following modifications: the initial amount of water introduced is 2672 cc, the amount of TTD initially introduced is equal to 161.8 g / 1 water; the polymerization pressure reached with the TFE turns out to be 12 bar absolute, the amount of initiator introduced (ammonium persulfate) turns out to be 48 ce. The initiator solution has the same molar concentration of Example 1, the reaction pressure (12 bar absolute) is re-established after each decrease of 0.5 bar by the semicontinuous feeding of liquid TTD and gaseous TFE, the weight ratio TTD / TFE = 13.8 between the two rnonómeros. 504 g of liquid TTD (initial charge excluded) are fed in total. After 380 minutes the reaction is stopped and a quantity of latex corresponding to 1.2% solids is discharged. The polymer is coagulated with 65% HNOa and dried in an oven at 110 ° C for 24 hours. The chemical-physical characteristics of the polymer are reported in table 2.

EXAMPLE 5 The procedure is the same as in Example 1 with the following modifications: the amount of demineralized water initially introduced turns out to be 2457 ce, the amount of TTD initially introduced is equal to 280 g / 1 water, the polymerization pressure reached with TFE turns out to be of 12 bar absolute, the amount of initiator (ammonium persulfate) initially introduced turns out to be 43 ce. The initiator solution has the same nominal concentration as that of Example 1. The reaction pressure (12 bar absolute) is reestablished after each decrease of 0.5 bar by the feeding of liquid TTD and gaseous TFE in the weight ratio TTD / TFE = 18.9 between the two rnonomers. 494 g of liquid TTD (excluding the initial charge are fed in total) After 500 minutes the reaction stops and the latex has an amount of solids corresponding to approximately 5% The polymer is coagulated with 65% HNOa and dried in an oven at 120 ° C for 24 hours.The chemical-physical characteristics of the polymer are reported in table 2.

TABLE 1 TABLE 2 ID

Claims (10)

NQVEPñP PE Lñ INVENCIÓN REINFORCEMENTS

1. The use of amorphous perfluoropolymers based on furnace polymers of TTD dioxol or their amorphous copolymers to prepare solutions in fluorine-containing solvents, to obtain solutions for coatings, in which TTD has the formula: wherein RF is a perfluoroalkyl radical with 1-5 carbon atoms, linear or branched when possible; X and X2 are equal to or different from each other with F or CF; the amount of TTD is in the range of 40 to 100 mole%.

2. The use of amorphous perfluoropolymers based on TTD dioxol honopolymers or their amorphous copolymers according to claim 1, wherein the other comonornero, in the case of the copolymers, is chosen from one or more of the following: tetrafluoroethylene (TFE), chlorotnfluoroethylene (CTFE), hexafluoropropene (HFP), perfluoroalkylvinyl ethers (PfiVE) of formula CFa = CF0R ', - in which is a perfluoroalkyl radical of 1 to 3 carbon atoms.

3. The use of amorphous perfluoropolymers based on TTD dioxole homopolymers or their amorphous copolymers according to claim 2, wherein the comonomer is tetrafluoroethylene, optionally in the presence of one or more comonomers in amounts of from 0.1% -20. % rnolar

4. The use of amorphous perfluoropolymers based on OTC polymers dioxol or its amorphous copolymers according to the indications 1-3, in which the formula of the TTD RF is CFa and Xa. V Xa are fluoride.

5. ~ The use of amorphous perfluoropolymers based on TTD dioxol homopolymers or their amorphous copolymers according to claims i-4, wherein the amount of TTD is in the range of from 50% to 95 mol%.

6. The use of amorphous perfluoropolymers based on TTD dioxol homopolymers or their amorphous copolymers according to claims 1-5, wherein the solvents are chosen from perfluorinated, optionally containing ethereal oxygen in the molecule or heteroatoms such as a nitrogen perfluoropolyethers containing perfluorooxyalkylene units and having perfluorinated end groups, optionally containing hydrogen.

7. The use of amorphous perfluoropolymers based on TTD dioxole homopolymers or their amorphous copolymers according to claim 5, wherein the melting point of the perfluoropolyether products is in the range of 60 ° C to 300 ° C .

8. - The use of perfl uoropol amorphous írneros based on ?? Oxygen copolymers of TTD dioxol or its amorphous copolymers according to claim 7, wherein the melting point of the perfluoropolyether products is in the range of 80 ° C to 160 ° C.

9. The use of amorphous perfluoropolymers based on copolymer furnaces of TTD dioxol or their amorphous copolymers according to claims 5-8, wherein the perfluoropolyethers contain the following units randomly distributed along the chosen chain of (CaF ^). O), (CaF-vO), (CFXO) wherein X is equal to F or CF3, (CR: LRs_CFsiCFí20) where R is equal to or different than 2 is H, F, perfluoroalkyl, Ca.-Ca.

10. The use of amorphous perfluoropolymers based on TTD dioxole homopolymers or their amorphous copolymers according to claim 9, wherein the perfluoropolyethers are chosen from: a) -0 (C3F <!, 0) m '( CFX0) n--, in which the unit (CaFß0) and (CFXO) are perfluorooxyalkylene units distributed randomly along the chain; m 'and n' are integers such that they give products with a melting point generally of 60 ° to 300 ° C, and m '/ n' is from 5 to 40, when n 'is different from 0; X is equal to F or CFa; n 'can also be 0; b) -OtCa-F ^ 0), -, - (CFXO) < _, - (CaF «iO) t- _, where p ', q' and t 'are integers in such a way that they give products with melting point indicated in a), p' / q 'are in the scale of 5 to 0.3, preferably 2.7-0.5; t 'can be 0 and q' / í '+ p' + t ') less than or equal to 1/10 and the relation t' / p 'is from 0.2 to 6; c) ~ (CR R¡: iCFs »CF: 20) r? - in the. that R and R2 have the meaning indicated above, and n is an integer such that it gives products with melting point indicated in a); the final groups are chosen from -CFa, -C2F3, -CaFv, -CF2H, -CFHCFa.