DE1032539B - Process for the production of polymers and copolymers - Google Patents

Description

GERMAN

The invention relates to a process for the preparation of a new and valuable group of fluorinated acrylic acid polymers. This consists in that monomeric normal 3-perfluoroalkoxy-2,2,3,3-tetrafluoropropyl ester Acrylic acid from the formula

CH ₂ : CHCOOCH ₂ · CF ₂ CF ₂ O (CF ₂ ) "F,

wherein η is an integer from 1 to 4 obtained by reacting S-perfluoroalkoxy-II-dihydropernuorpropyl alcohol of the formula

F (CF ₂ ) _n OCF ₂ • CF ₂ • CH ₂ OH

with acrylic acid in the presence of an accelerator such as perfluoroacetic anhydride, or with acrylyl chloride or Acrylyl fluoride are produced, are polymerized.

The monomers can be homopolymerized to give rubber-like polymers which, in turn, can be vulcanized will. In this way, vulcanized rubbers can be produced, which have a unique Have a combination of valuable properties, including flexibility at low temperatures, excellent Resistance to oxidation by air, pure oxygen and ozone, excellent Resistance to hydrocarbon fuels, aliphatic and aromatic oils, hydraulic Ester type fluids, synthetic lubricants and common organic solvents, excellent resistance to nitric acid and finally resistance to itself elevated temperatures (up to at least 175 ° C). These homopolymers can be made from polyfunctional Amines existing hardeners or vulcanized in some other way. The monomeric esters can copolymerized with butadiene and other olefinically unsaturated monomers and these copolymers vulcanized with sulfur or in any other suitable manner for homopolymers. The value of the polymers is greatly increased in that they are easily vulcanizable. The swelling in liquids is reduced, and durability, tear strength and elasticity are increased.

The monomeric starting materials are therefore the normal 3-perfluoroalkoxy-2,2,3,3-tetrafluoropropyl ester of acrylic acid, containing 3 to 6 fully fluorinated carbon atoms in the molecule and by the following formulas can be reproduced, the second being an abbreviated form:

CH _2: CHCOOCH ₂ CF ₂ CF ₂ O (CF ₂₎ "F
CH ₂ : CHCOOCH ₂ C ₃ F ₄ OC "F ₂ " + _x

where η is an integer from 1 to 4.

The present compounds contain a "Kthei" oxygen atom in the fluorocarbon chain. The position of this oxygen atom is of critical process

for the production of polymers
and copolymers

Applicant:
Minnesota Mining and Manufacturing

Company,
St. Paul, Minn. (V. St. A.)

Representative: Dr.-Ing. H. Ruschke, Berlin-Friedenau,

and Dipl.-Ing. K. Grentzenberg,
Munich 27, Pienzenauerstr. 2, patent attorneys

Claimed priority:
V. St. v. America December 21, 1953

Frank A. Bovey and Joseph F. Abere,

St. Paul, Minn. (V. St. Α.),
have been named as inventors

for the usability of the polymers produced from these esters. From the above formulas it can be seen that this oxygen atom is connected to the third (γ-) carbon atom, which is the second fluorinated carbon atom, so that it is separated from the alcohol or ester oxygen atom by 3 carbon atoms. The alcohols of the esters can be viewed as derivatives of the normal 2,2,3,3,3-pentafluoropropyl alcohol in which one terminal fluorine atom has been replaced by a perfluoroalkoxy group, F (CF ₂ ) "O-". The ether-like bonded 0 atom does not have "ether" properties in the sense of organic chemistry,

The ether oxygen atom in the fluorocarbon chain changes the properties of the compounds in the desired manner, so that polymers with the properties described can be obtained. The vulcanized homopolymers of the present acrylate are contained at 15 to 3O ⁰ C succumbing low temperatures flexible than the corresponding cured acrylate homopolymers of which no etheric oxygen atom. The good resistance of the polymers at high temperatures is retained. This oxygen atom greatly reduces the refractive index of the polymers.

The perfluoro "ether" chain is both oleophobic and hydrophobic. The homopolymers of acrylic acid

809 557/498

Esters are both water and oil repellent and non-flammable in the sense that they are burned is not entertained. These homopolymers contain at least 49 percent by weight bound Fluorine.

The carboxyl group in the polymeric molecule additionally imparts desirable properties. Particularly these active groups increase the adhesiveness when the polymer is applied as a coating to a surface and bring about the adhesiveness in the rubbery polymeric composition. The polymers form tough films on a large number of substrates, including fabrics, papers, Cellulose films and metals, probably due to the binding capacity of the carboxyl groups and the molecular ones Orientation when applying the surface coatings.

Although the homopolymers are insoluble in the usual organic solvents, they are insoluble in others Solvent soluble, which is very important for the application of coatings from these solutions. as The alkyl esters of fluorocarbon monocarboxylic acids can be used as solvents and plasticizers for these polymers and perfluoroalkyl alcohols with unfluorinated 1-C atom and their esters are used.

The homopolymerization and the heteropolymerization of the monomeric esters can easily be carried out in bulk, in solution, be carried out in suspension or in emulsion (cf. US Pat. No. 2,642,416). The emulsion polymerization in aqueous medium is preferred and gives permanent, translucent latices. Persistent Latices with 25 to 35% solids content can easily be produced.

The structure of the homopolymers is given by the following basic formula of the repeating ester units specified:

HCH

HC-C '

, 0

0-CH ₂ CF ₂ CF ₂ - 0 - (CF ₂₎ "F

The polymeric molecule contains a large number of such units, the vinyl groups being linked to one another to form a linear chain. The 3-perfluoroalkoxy-2,2,3,3-tetrafluoropropyl groups provide terminal fluorocarbon ether side chains with 3 to 6 completely fluorinated carbon atoms and a terminal trifluoromethyl group. Heteropolymer, which is formed by copolymerization of the present esters with other polymerizable monomers containing an ethylene bond, contains the chain of the polymer both from acrylic acid ester units of the above constitution as well as units originating from the other monomeric component. Examples of such mixed components are butadiene, styrene, acrylonitrile, isoprene, vinyl ethers, acrylic methacrylic acid esters and halogenated derivatives of such monomers, e.g. B. perfluorobutadiene and fluoroprene. It is also possible to use acrylic acid esters of perfluoroalcohols which are unsubstituted in the 1-position and contain no ether oxygen atom (CH ₂ : CHCOOCH ₂ C "F _{2; l} + J.

Copolymers obtained using dienes (e.g. butadiene) can be mixed in the usual way with sulfur, the homopolymers of monomeric acrylates with oxides of divalent metals (e.g. magnesium and lead oxide) and with a hydrate of an alkali silicate (e.g. B. Na ₂ SiO ₃ · 9H ₂ O) together! with a base (e.g.

Calcium hydroxide) are hardened. Preference is given to vulcanizing with a polyfunctional amine (e.g. triethylenetetramine) mixed with a reinforcing pigment (e.g. carbon black).

The perfluoromethoxy, ethoxy, propoxy and butoxy alcohols, which are used to produce the monomeric acrylic acid esters used as starting materials, have approximately the properties given in the following table:

formula

CF ₃ OC ₂ F ₄ CHoOH
C ₂ F ₅ OC ₂ F ₄ CH ₂ OH
C ₃ F ₇ OC ₂ F ₄ CH ₂ OH
C ₄ F ₉ OC ₂ F ₄ CH ₂ OH

boiling point

in ⁰ C
(at 740 mm)

98
106
120
136

1.289 1.287 1.289 1.292

1.595 1.600 1.650 1.698

These 3-perfluoroalkoxy-2,2,3,3-tetranuoropropyl alcohols

can be achieved by reducing the methyl (and ethyl) esters of the normal perfluoro - (/? - alkoxypropion) acids by means of Lithium aluminum hydride can be produced as follows:

F (CFa) _n OCF ₂ CF ₂ COOCH ₃

TiAlTT

> - F (CF ₂ ) "OCF ₂ CF ₂ CH ₂ OH

The perfluoro (ß- alkoxypropion) acids used to produce the methyl (and ethyl) esters can easily be produced by hydrolyzing the corresponding sodium or potassium salts with the aid of concentrated sulfuric acid and distilling off the perfluoric acids. The salts can easily be prepared by hydrolysis of the corresponding acid fluorides in aqueous NaOH or KOH solution.

The preparation of these compounds is described in detail in U.S. Patent 2,713,593.

The polymerizable monomeric acrylic acid esters used in practicing this invention can only be easily produced by esterifying acrylic acid with the fluorinated alcohol if a suitable accelerator is used, for which perfluoroacetic anhydride is well suited. After a Another method is to react the acrylyl chloride with the alcohol. Both procedures are described below explained:

The apparatus used was a dry four-necked flask with a capacity of 50 cm and fitted with a thermometer, a dropping funnel, a water-cooled reflux condenser connected to a calcium chloride tube, a gas inlet tube, a magnetic stirrer and an electric heating jacket i ¹ The whole apparatus was dried at 120 ° C and composed hot ■. Dry nitrogen was slowly introduced through the inlet tube (one bubble per second).

The sr flask was charged with 13.6 g (0.150 mol) of acrylic acid _{chloride, CH 2} : CHCOCl, and 0.3 g of hydroquinone (as a polymerization inhibitor). The mixture was stirred and refluxed with constant bubbling of nitrogen. Then 13.3 g (0.052 mol) of 3-perfluoroethoxy-2,2,3,3-tetrafluoropropyl alcohol, C ₂ F ₅ OC ₂ F ₄ CH ₂ OH, were added dropwise over the course of 7 hours, after which the refluxing was reduced Stirring was continued for a further 2 hours.

The reaction mixture was distilled in a column with five theoretical plates and resulted in AW5 separate the unreacted acid chloride into two main parts factions. The first fraction (14.2 g) boils between and 54 ° C and 30 mm and has the refractive index 1,

5 6

at 24 ° C. The second fraction (1.6 g) boils at 54 ° C. and filtered, the filtrate (49.3 g) with 0.2 g of hydroquinone

30 to 35 mm and has the refractive index 1.3736 when mixed and in the above-mentioned column with five and

24 ° C. The first fraction was distilled four times with 5 ecm of a twenty trays.

5% sodium carbonate solution and once with 5 ecm. The fraction from bp ₉ 44 to 45 ° C fell in an amount

washed distilled water, each time from 5 of 45.6 g. It had a refractive index of 1.3190 and

the aqueous layer was separated. The latter was determined by analysis to be the desired monomer

The organic layer obtained was practically over 0.5 g of water-fluorinated propoxypropyl ester of acrylic acid

dried free magnesium sulfate and then filtered. identified in pure form. The yield was 85%.

(The washing water and the solid desiccant were

successively extracted with ether, which after drying io The analysis showed:

and evaporating an additional 0.8 g of the desired mono- Found. C 29 1 ° / F 56 4 ° / ·

meren ethoxy ester in a purity of 90 to 95% calculated ... C 29, '2 ⁰ L, F 56.5 ° / °.'

revealed.)

The dried organic filtrate was added carefully for the preparation of the 0.1 g hydroquinone described above in a column with five starting materials, no protection is sought,
and twenty theoretical trays containing small copper coils (to prevent polymerization), production of the ester polymers
divided into three fractions. The second fraction (9.4 g)

boils at 53 to 54 ⁰ C and 30 mm, has the refractive For the production of a latex dispersion is generally

index 1.3183 at 25 ⁰ C and was determined by analysis as the 20 mean the emulsion polymerization in an aqueous

desired monomeric ethoxyacrylate in relatively carrier liquid is preferred. The following are two

identified in pure form. typical recipes given:

AWAY

The analysis showed: _. ,,,.,

^{J b Place by} Weight Found ... C 29.8%, F 53.6%; 25th

calculated ... C 30.0 <V ₀ , F 53.4%. Monomeier ester. . 00 100

Water (deoxygenated) 180 180

In a three-necked flask with a capacity of 100 ecm filled with emulsifier (sodium lauryl sulfate) 3 J3

a thermometer, a drip funnel, one with ■ J ^3T ^ ⁱ _r) 7

Water-cooled reflux condenser and a stirrer 30 £ ^a | * ⁸ ~ "

was provided and contained 0.2 g of hydroquinone, ¹ ^ a ⁰ S 0.5

Added 11.0 g (0.153 mol) of acrylic acid. The mixture

was cooled from 6 to 15 ^{0 C with water.} Then the reaction vessel becomes with the aqueous phase

charged at 15 ⁰ C 1 ecm perfluoroacetic anhydride in 4 parts, displaced the air with nitrogen and then added the. The mixture was ^{cooled to 13 °} C. and 35 monomeric esters were added. After closing the anhydride then further up to the total amount of 33.6 g of the vessel, the mixture is heated to 5O ⁰ C and 2.5 added to (0.160 mol) at such a rate that was stirred for 6 hours or shaken, the higher the temperature 13 up to 15 ° C. The solution ester will take longer to implement. The entwurde stirred another 15 minutes at 14 to 16 ⁰ C, Toggle standing latex is stable and can be stored closing cooled to 10 ° C and then rapidly within 4 °. It can be used as such, for example as an impregnation agent, for 5 minutes with 46.0 g (0.1455 mol) of normal 3-perfluoro coating or pouring agent.
propoxy-2,2,3,3-tetrafluoropropyl alcohol, the latex can be diluted and frozen out,

wherein the rubber-like polymer flocculates, the

C ₈ F ₇ OC ₂ F ₄ CH ₂ OH, then washed with water and 24 hours at 5O ⁰ C

45 is dried, a dry polymeric mass

offset. After removing the cooling, the temperature rose, which was sticky and hung on a glass container the solution remains in 15 minutes as a result of the exothermic.

Reaction at 33 ⁰ C. Using a warm water bath The homopolymers of the methoxy and Äthoxyester

it was further increased to 4O ⁰ C; These temperatures have good resilient-elastic properties. This was maintained by heating the bath with the flame of a homopolymer of propoxy and butoxy ester micro-burner during the entire 4-hour reaction time (counting from the addition of the alcohol), but is greatly improved by vulcanization, obtain. Heteropolymers can be found in a similar manner

The solution was cooled to 1O ⁰ C and produce a cold emulsion polymerization process. Thus, aqueous 10% sodium chloride solution (45 ecm, a mixed polymer of the present alkoxy monomers corresponding to about half the weight of the reaction mixture with corresponding fluorine-containing acrylic acid esters, the corresponding amount) slowly at a maximum of 15 ⁰ C to contain no ether oxygen atom (cf. the USA. -Patent hydrolysis of excess anhydride added. It figuration 2 642 416), can be produced by two layers. The lower (organic) recipes above, but using one layer, was separated in a separatory funnel and worked in 60 other polymerizable monomers. Mixing the flask returned, ^{cooled to 10 to 15 0} C, polymers with butadiene can be produced, with 22 ecm (one ^{cooled to below 15 0} C) 10% by adding butadiene to the vessel, treating the entire NaCl solution, whereupon the organic layer, the charge of monomers in the following recipe, was separated off in a separatory funnel. This treatment is given 100 parts. In this case, the fluctuation was repeated four times. Finally, the product was 65 reaction times at 50 ⁰ C between 3 and 24 hours. In order to achieve the best results with a mixture of 15 ecm of 13% Na ₂ CO ₃ - the conversions of solution and 10 ecm of 5% NaCl solution should not exceed 65 to 70%. It is also said to be an antioxidant wash. The resulting, not dried organic dationsmittel, z. B. Phenyl- / 3-naphthylamine, either layer (50.6 g = 94.1% crude yield) was added over 1.0 g of the latex or dried in the dry mixed poly anhydrous magnesium sulfate, the mixture 70 merisat are rolled.

You can also polymerize in bulk and in solution; also use mercaptan or other linking agents to produce polymers with a low average Molecular weight, e.g. B. to obtain liquid polymers. The latter can become solid rubbery ones or non-rubber-like materials are vulcanized.

The following processing formula for the vulcanization of the present acrylate homopolymers and copolymers of the ester monomers with butadiene sees the use of an alkali silicate in conjunction with a Base before:

Parts

Polymer 100

Parts

Polymer 100

Stearic acid 1

ZnO 5

Accelerator (benzothiazyl disulfide) 1.5

Sulfur 2

Gas black (easily processable carbon black) 35

The ingredients were mixed at 6O ⁰ C in a mill and at the vulcanization of the test strips in a press at 126 and from 150 ⁰ C in 45 minutes. These strips were firm, highly elastic and springy. The following physical properties were determined on them.

Na ₂ SiO ₈ -9H ₂ O

6.72

₂₈₂
Ca (OH) ₂ 2.72

~ The hardeners were tested on a small two-tensile strength (kg / cm)

roller mill at 60 ° C into the rubber-like polymer so ±! ^enmm £ ^{m zu} ™ / f ^ucü I '<"·

incorporated. The samples were in the form of experimental £, ^orm ^ ^üerUBg <■ ^{/ o)}

strip in a press at 126 at pressure 1 hour at ¹⁰ ^ '

Hardened at 150 ^{° C.} The measurement of the percentage swelling at 70 hours

The resistance of the vulcanized test subjects dipping test strips in sebacic acid dioctyl

strip against solvents was determined by measuring 25 esters at 100 ^° C. for the vulcanized 38:52 mixed

Butadiene copolymer 48:52 I 20:80

24.5 40 0 41

115.5 140 3 56

the percentage increase in volume (swelling) after immersion for 48 hours at 25 ° C. in a a mixture of 70 parts isooctane and 30 parts toluene, b isooctane and c benzene. Flexibility at low temperatures was determined by measuring the torsional modulus in a Gehman apparatus at 25 ° C and measuring the modulus at reduced temperatures to determine the temperature at which the modulus reached 10 times that obtained at 25 ° C. (This temperature is the Gehman value " _TIQ ".)

The following table shows the values for vulcanized rubber-like homopolymers of methoxy, Ethoxy, propoxy and butoxy esters indicated:

polymer the value 15% and for the 20:80 mixed * polymer 79 ° / ₀ .

There were now samples for 48 hours at 25 ° C in the The following organic fuels and solvents are immersed and the percentage swelling of the strips measured:

solvent

Isooctane toluene (70:30)

benzene

toluene

Isooctane

Methyl isobutyl ketone ...

Mixed polymer 20:80 i: 51 130 50 130 50 130 45 85 30th 90 45

Ester

Methoxy
Ethoxy.
Propoxy.
Butoxy ..

% Swelling (48 hours at 25 ⁰ C) m benzene Isooctane Isooctane 16 toluene 7 to 12 70:30 7th 13th 10 29 10 to 15 7th 12th 13th 2

T ₁₀ ( ⁰ C)

-32 -23

QC

-31

Comparative tests have shown that the resistance to swelling is about as good as in the case of the corresponding vulcanized rubber-like

40 The two vulcanized copolymers then have good properties. The copolymer with the higher butadiene content is stronger, more elastic and has better properties at low temperatures; the 48:52 copolymer resists fuels and solvents better.

A rubber-like 54:46 copolymer of the fluorinated methoxypropyl ester of acrylic acid with butadiene was vulcanized with sulfur in the manner described above. Test strips from him had the following Characteristics:

Tensile Strength (kg / cm ² ) 143.5 '

Elongation to break (%) 450

T ₁₀ ( ⁰ C) -38 °

Homopolymers of the earlier perfluoroacrylates are 55 _percent swelling after 48 hours at 25 ° C

contain no ether oxygen atom; but the T ₁₀ values according to Gehman are 15 to 30 ° C lower.

The vulcanized butadiene copolymers are less resistant to solvents (i.e. they show a larger swelling volume), but the T ₁₀ values according to Gehman are lower. There was obtained values down to -50 to -6O ⁰ C for copolymers, which (according to analysis of the polymers) containing 20 mole percent of the acrylate.

The following describes the vulcanization of two butadiene copolymers explained with sulfur. The polymers were made of rubber-like copolymers fluorinated ethoxypropyl ester of acrylic acid and butadiene in a molar ratio of 48:52 and 20:80, respectively. The processing formula was the following:

Isooctane-toluene (70:30) 60

Isooctane 20, ·.

Benzene 60

The preferred method of achieving good flexibility at low temperatures and the greatest resistance to fuels, oils, solvents and hydraulic fluids is to ^; Use of the homopolymers of fluorinated Me- ;; thoxy and ethoxypropyl esters of acrylic acid and the; Vulcanization with a polyfunctional amine (e.g. triethylenetetramine) as a hardening agent mixed with a reinforcing pigment (e.g. carbon black). ,1:

Such recipe # | explained. " ■ '' ■ '"'"%

Claims (1)

9 10 A B test strips were placed in light at 25 ° C for 1 week Parts by weight of fuming nitric acid immersed; they just oozed Polymer 100 100 30 to 40%. They did not show deterioration, but rather Stearic acid 11 remained solid and rubber-like. A sample of the Q _asru ß 35 35 5 vulcanized polymer B was 100 hours in air Sulfur 1 1 ^{heated at 177 0} C and suffered only 35% strength Triethylenetetramine '. ".' ................. 1 1.75 loss without changing the final elongation to show. Another sample was 100 hours in a Using a rubbery methoxy synthetic homopolymer prepared from dioctyl sebacate, samples were immersed at 177 ° C. by mixing the lubricants. Swelling joined components in a rubber mill at 6O ⁰ C and VuI- not paid, the strength loss was only 18% and kanisationsstreifen in a press for 1 hour at 150 ⁰ C and the elongation experienced no change. Another made. The vulcanization converted the polymer sample was immersed in boiling water for 70 hours; in each case from a thermoplastic to one it swelled by 47%, but was otherwise not attacked,
strong and elastic rubber around; In the above curing process with the amine, however, product B does not serve as strong or elastic as carbon black as a reinforcing pigment which increases the tensile strength of product A. The vulcanized polymers had considerably increased; Sulfur prevents premature chasing properties: wetting during processing and increases the A B reversibility at elevated temperatures, while the Tensile strength (kg / cm ⁸ ) 74.2 43.4 20 stearic acid facilitates processability and closes Elongation to break (%) 270 90 Hch also catalytically promotes the crosslinking reaction. Change in shape until breakage (%) 8 4 T ₁₀ ( ⁰ C) -25 -22 Embrittlement point ( ⁰ C) -37-39 Claim: Percentage swelling after 48 hours 25 at 25 ° in processes for the production of polymers and Isooctane-toluene (70:30) 23 14 copolymers, characterized in that Benzene 26 18 monomeric normal S-Perfhioralkoxy - ^^ SjS-tetra- Acetone 59 61 fluoropropyl ester of acrylic acid of the formula Ethyl acetate 69 73 30 Isooctane - 9 CH ₂ : CHCOOCH ₂ CF ₂ CF _a O (CF _a ) "F, Methyl isobutyl ketone - 33 Methyl ethyl ketone - 62 where η is an integer from 1 to 4, in solution, in Ethyl alcohol - 9 suspension, in bulk or in emulsion on its own Sodium hydroxide (10%) - 160 35 or with other polymerizable monomers Sulfuric acid (10 ° / _o solution) - are polymerized. 3 © 809 557/498 6.58