DE2620284A1 - PROCESS FOR THE POLYMERIZATION OF TETRAFLUORAETHYLENE AND MODIFIED TETRAFLUORAETHYLENE POLYMER PRODUCED BY THE PROCESS - Google Patents

Description

Process for the polymerization of tetrafluoroethylene and modified tetrafluoroethylene polymer made by the process

The invention relates to a modified high molecular weight Tetrafluoroethylene polymer, which is used in particular for paste extrusion by nozzles at an increased reduction ratio, and a method for producing the polymer.

Fine powder of tetrafluoroethylene polymer (hereinafter referred to as "TPE polymer") is produced by that one coagulates an aqueous dispersion of a TPE polymer produced by emulsion polymerization of tetrafluoroethylene (hereinafter referred to as "TPE"). The fine powder of the TPE polymer is mixed with liquid lubricants, e.g. with high-boiling hydrocarbons having a carbon number of 9 to 12, and the resulting mixture becomes thin rods or tubes according to a usual one

76- (DKG 515-064) -Bo-HÖ

609847/0934

Paste extrusion method deformed by nozzles called paste extrusion referred to as. The extrudate becomes a belt with calender rolls for use as a green belt Calendered. If the extrudate is in the shape of a tube, it is finally processed into the end product by sintering.

riei the paste extrusion method, it is necessary that the Operation is carried out with the highest possible efficiency, so that a high productivity is achieved and that molded product finally obtained by sintering the extrudate has high mechanical strength.

The productivity largely depends on the reduction ratio in the extrusion process, the extrusion pressure and the extrusion speed away. The reduction ratio is given by the ratio of the cross-sectional area (S) of the cylinder, into which the paste material is added is expressed in relation to the cross-sectional area (s) of the nozzle of the extruder. Preferably that is Reduction ratio (S / s) large; with a high reduction ratio, a large amount of TFE polymer paste can be in the Extruding cylinder given each time during the extrusion cycle will. Furthermore, in practice, high reduction ratios are often required without exception, e.g. for extruding a Object with a very small cross-sectional area when the coating of an insulated electric wire by paste extrusion will be produced.

The paste extrudability of the fine powder of the TFE polymer largely depends on the conditions under which the fine powder of the TFE polymer is produced. For example, when comparing the extrudability of various TFE polymers under constant extrusion conditions such as constant speed, constant temperature and the same amount of lubricant, the allowable upper limit of the reduction ratio (hereinafter referred to as "limit reduction ratio") of the powder depends of the TFE polymer largely from powder to powder depending on the conditions

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the production of the I ¹ FE polymer. If the powder is extruded at a reduction ratio above the limit reduction ratio of the powder, a corrugated or screw-shaped extrudate is obtained, or cracks occur on the surface or inside of the extrudate due to the shear force, and in extreme cases the product is broken during extrusion. Accordingly, the desired extrudate is not obtained.

In view of productivity, the extrusion pressure should not become too large even if the reduction ratio is high aspired or achieved. The limit reduction ratio of the fine powder of the TFE polymer and the extrusion pressure are influenced by the extrusion speed. The higher the Extrusion speed, the higher the extrusion pressure and the lower the required limit reduction ratio of the polymer.

In paste extrusion, it is also necessary that the extrudate, after sintering, a product with good mechanical properties Properties there. When the paste of the fine powder of the TFE polymer through nozzles at a high reduction ratio is extruded, the TFE polymer particles are in the extrusion direction oriented and subject to high shear stress. Accordingly, the shaped Product obtained during the subsequent sintering has a high tensile strength in the directions at right angles to the direction of extrusion (in the extrusion directions at right angles to the extrusion direction). Molded products for the one high mechanical strength is required, or molded products, such as pipes, that are "subjected to high internal pressure however, are required to have improved strength in the directions perpendicular to the extrusion direction.

It is also desirable that the extrudate can be sintered with good dimensional stability. That is an essential one Requirement in the production of coatings for electrical

609847/0934

Wires rait TPL polymer.

This paste extrudability depends almost entirely on the Properties of the TFL polymer used, including from the conditions under which it is produced.

Although fine powder of TFE homopolymer provides an extrudate showing generally satisfactory mechanical strength after sintering, it is capable of improvement in productivity, that is, the limit reduction ratio of the polymer and the extrusion pressure. To improve these properties, it is known to modify homopolymers of TFE according to Ub-PS 3 1 ^ 2 663 and GB-PS 1 253 59S. In the US-PS 3 1 ^ 2 665 high molecular weight dispersion polymers of at least 90 % TFE polymers are proposed, which can be extruded in the form of a paste at a high reduction ratio and are obtained by polymerizing TFE in the presence of so-called modifying agents. In this method, perfluoroalkyl and perfluoroalkoxyethylene compounds are used as modifiers, which can be polymerized under the polymerization conditions. However, these polymers have a problem that high-speed extrusion involves an increase in the extrusion pressure. Furthermore, the extrudates made from the modified TFE polymers have a low mechanical strength after sintering, especially in the directions at right angles to the extrusion direction, which means a serious disadvantage of sintered products in the form of tubes or hoses.

The extrudate, which is made from the modified TFE polymer according to U.S. Patent 3,126,665 is poor in dimensional stability during sintering, i.e. in the case of processes for coating electrical wires, the inside diameter falls of the TFE polymer coating after sintering is larger than the wire diameter, and only wires with poorly fitting covers received.

609847/0934

In üer Gb Pü 1 2 ^^ b9ö a method is bescnrieben, in the step, a dispersion with a solids content of 5 ois Ib wt .-% by frischpolymerisieren of TPE with Äthylennalogenia is prepared una then TFE in a second vessel in the presence of the resulting Polymers as "Keimpoiymeres" to achieve a concentration of 15 to 40 wt .-; g of the i'FE polymer is homopolymerized.

Cugleieu the polymer obtained by this process has a better limiting reaction ratio than TFE homopoly meres, this polymer is still unsatisfactory because a very low extrusion pressure to extrude this polymer uat a high speed is required and an extrusion Dei a high reduction ratio of about lüüü or more cannot be performed. The procedure also has the disadvantage that the desired polymer is obtained in low yield.

The object of the invention is to provide a modified TFE polymer with high productivity and to provide a process for making aes polymer. In particular, it is the task of r-invention, a modified TFE polymer with a high Limiting Reaction Ratio and a Process for Making the Polymer, a modified TFE polymer that is used in low extrusion pressure is extrudable, and a process for the production of aes polymer and a modified TFE polymer, which is extrudieroar at low extrusion pressure even at high iixtrujionagesch SPEED, and a process to provide for the production of such a TFE polymer.

It is also an object of the invention to provide a modified TFE polymer for producing an extrudate which can provide articles with good mechanical properties after sintering, and a method for producing the modified TI ⁵¹ E polymer.

furthermore it is the task of the invention, a modified one

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xFE polymer to produce an extrudate that is extremely low shrinkage, and provide a method for making the TFE polymer.

According to the invention, it is an object of the invention to provide a process for fixing a modified I ¹ FL polymer with high yields.

The tasks and characteristics of the invention are in the explained in more detail below.

r> ei the modified ^r ± FE polymer according to the invention is uia a polymer, which is obtained by polymerizing tetrafluoroethylene with a mischpolymerisieroaren modifier in an aqueous medium which contains a polymerization initiator and a dispersant ₃ so that the resulting polymer 0.001 contains up to 2% by weight of the copolymerizable i * iodifier based on the weight of the polymer, the polymer being characterized as follows:

(1) Lei the copolymerizable modifier is at least one compound selected from chlorotrifluoroethylene, hexafluoropropylene and omega-hydroperfluoroolefin of the formula CF ₂ = CF (CF ₂ CF ₂ ) _n il (where η is an integer from 1 to 5) geo-educated group and

(2) at least 10 % by weight of the copolymerizable modifier which is incorporated into the polymer, are introduced into the polymerization system after 70% by weight of the polymer which is ultimately formed, with at least 50% by weight having been formed. -% of the copolymerizable modifier, which is incorporated into the polymer, are contained in the shell regions of the particles of the polymer.

In the process according to the invention, an emulsion polymerization is used carried out in the presence of a dispersant. That Polymer is obtained in the form of colloidal particles in an aqueous dispersion and the average particle size of the polymer is in the range from about 0.2 to about 0.5 wm.

609847/0934

ORIGINAL l ^ SF ^ CTZD

The fine powder of the modified ¹ TFE polymer is obtained after coagulating the dispersion and drying the resulting solid.

In general, in the emulsion polymerization of the TPE, the number of particles of the polymer does not increase or decrease in the course of the polymerization with the exception of the first stage of the polymerization, in which the cores of the particles of the polymer are formed, inter alia, after the first stage, the polymerization takes place only with an increase in particle size, but without changing the number of particles. It follows from this fact that at least 50% by weight of the interpolymerizable vodification agent incorporated in the polymer according to the invention is present in the outer dumbbell regions, which make up at most 30% by weight of the total weight of the particles.

The TFE polymer obtained by the process according to the invention contains 0.001 to 2 Άοΐ-yö, preferably 0.01 to 1.0 mol-Å of modifier based on the total weight of the polymer. If the modifier is the omega-hydroperfluoroolefin listed above, the preferred amount of the modifier is 0.01 to 0.05 I ^v iol / fc based on the total weight of the polymer. Since the surfactant is mainly contained in the outer shell portions of the particles, the modified TFE polymer according to the invention ensures high productivity because it is produced at a high reduction ratio and at a high speed under a relatively low pressure without deteriorating excellent physical and mechanical properties is extrudable, and has particularly excellent resistance to heat and chemicals that TFE homopolymers have; it provides molded articles with excellent mechanical strength.

In the modified TFE polymer powder according to the invention does not have the disadvantage of the known powder in which

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it is difficult to achieve a continuous relationship with the current: Obtain extrudate with a small reduction ratio, e.g. with a ratio of less than 100.

In accordance with the invention, it is preferred that in the above process the copolymerizable modifier in the polymerisation system in a concentration of at least 0. Cl KoI-Jo based on the total amount of TFE and des Modifier is present after 90 wt Finally formed polymers have been formed. When the modifier in the polymerization system in the above Manner, the molded article made from the resulting TFE polymer powder has a high mechanical strength after sintering, especially high tear strength in the directions perpendicular to the extrusion direction.

According to the invention, in the above method, the polymerizable modifier in the polymerization system be introduced so that at least 0.001 weight percent of the modifier (based on the weight of the polymer formed in the end) are contained in the core area, which is 30 wt .- ^ des corresponds to polymers formed in the end. This will reduce the shrinkage of the extrudate from the resulting TFE polymer powder is produced when the extrudate is sintered.

The content of the modifier in the TFE polymer, which according to obtained by the method according to the invention can be determined by IR absorption analysis. If e.g. chlorotrifluoroethylene is used as a modifier, it can be determined using the absorption band at 957 cm (C-CT). Further can distribute the modifier from the core to the outer cladding the polymer particles - as will be described later according to the vapor phase analysis in the course of the polymerization for Preparation of the polymer or, alternatively, can be determined by the fact that one of the polymer several times during the polymerization

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tion samples are taken and the i-iodifying agent content of each Measure sample by IR absorption analysis.

The polymerization of the TPE according to the invention is carried out according to known general procedures carried out «

For polymerization, deionized water is placed in a reactor equipped with a temperature control device. Thereafter, a dispersant and a polymerization initiator are charged into the reactor. Set the temperature TF _s £ added until the pressure reaches a certain value _s and the mixture _stirred} thereby starting the polymerization.

The polymerization temperature is advantageously maintained at a fourth in the range of O to 100 ⁰ G. The polymerization

p ρ

pressure is ί to 100 kg / cm (overpressure; kg / cm G), preferably 3 to 50 kg / cm ^ (overpressure). The internal pressure of the reactor is maintained by the vapor of the TFE "As TPE is consumed with the progress of the reaction and the pressure drops, fresh TFE _s is introduced under pressure into the reactor by the predetermined pressure to maintain each time the internal pressure to a certain value ( eg with every decrease of

ρ
1 kg / cm) drops below the initial pressure. The amount of polymer formed can then be calculated from the amount "of each TPE batch (pressure difference) and the frequency of loading. It is then easily possible _{to determine 9} the time for adding the modifying agent, if the amount of polymer, that should finally be formed _s and the time j at which the i-iodif iziermittel should be added to polymers are given.

The modifier can be introduced into the polymerization system by various suitable methods. For example, a small vessel in which the required amount Modif is iziermittel _s are provided between the TFE Behalter- and the reactor sur same time is inserted into the aas Mocifizieraiittel when the IFE aingessts-i is,

609847/0934

ORIGINAL WSPECTED

Jas insert zveri.ältnis νοϊ. Modifying agent to Trb is determined on the basis of the polymerisation reactivity ratio. For example, when the f-iodifiziermittel chlorotrifluoroethylene is essentially the same Folymerisatiansreaktivitatwie TFE has _s can be the monomer composition in the rolymerteilchen in such a manner are regulated so that the foononerzusammensetzung is genalten in Folymerisationssystem so, the composition AASS the desired PoIymerteilchen is the same. Intended in particular to at least 50 parts by weight of the S Chlortrifiuoräthylens that incorporated into the polymers are introduced into the polymerization xerden _{s 3} after, preferably immediately after, IQ wt -.% TFE formed in the end polymerized v / are orden!. Ba Chlortrifluoräthyien is highly reactive, is the Chlortrifiuoräthylens _s which was used in the polymerization system, immediately after the polymerization has expired to 70%, incorporated großer- a proportion in the formed polymers. If, after the formation of SQ Gev; "- £ of the polymer ultimately formed, the concentration of the miscible polymerizable modifier is at least C - ,, 01 mol- :! EASIS on the total amount of TPE and Kcdifiz-iermittei is maintained in the polymerization system, Contains the outermost region of the 'particles at most 10 parts by weight DER _s ife of the polymer obtained at the end corresponding to the ffiischpolymericisrbare r-iodifiziermittel in a Eonsentration of at least 0 _s 0i KoI- ^.

Be introduced Y.enn further comprises at least 0 _r 00i QeVc-% of copolymerizable r-Iodifiziermitteis EASIS on the weight of the polymer formed at the end in the polymer-ionssystem _s before 30 wt -.% Of the polymer formed at the end have been formed, at least 0 _: 00i Gew ^ -Z of the misehpolj / merisable I-oliifisiermittel based on the weight of the polymer-en formed at the end in the core area of the particles of the polymer contain.

the Koclifisisriritiel in the Polymerisatioassystem in the

: .- t '-is. : ii: rjn'i: - dis polymes irnnit ^ slbar afterwards with the

Γ; ". '; - te Ce : ?? OljKrii-" thn eincef'ih: .- t ' -ist. : ii: rjn'i: - dis polymer-

Result that the reaction takes more time. However can a major influence on the total polymerization time can be avoided by introducing the modifier largely delayed or reduced the required amount of the modifier.

Examples of compounds of the formula CF ₂ = CF (CF ₂ CF ₂ ) _n H according to the invention as copolymerizable modifiers are CF ₂ = CFCF ₂ CF ₂ H, CF ₂ = CF (CF ₂ CF ₂ ) ₂ H, CF ₂ = CF (CF ₂ CF ₂ KH, CF ₂ = CF (CF ₂ CF ₂ ) ^ H and CF ₂ = CF (CF ₂ CF ₂ ) H ₃ where CP ₂ = CFCF ₂ CF ₂ H and CF ₂ = CF (CF ₂ CF _{2) 2} H are preferred.

Polymerization initiators which can be used according to the invention, are ammonium persulfate, potassium persulfate, sodium bisulfite, Disuccinic acid peroxide and various other known ones. Starter. You can use them alone or in a mixture of e.g. more can be used as two connections. The polymerization can also be started by ionizing radiation.

As the dispersant, anionic surface active agents are suitable, of which polyfluoroalkyl type compounds are preferred. Examples are alkali metal salts and ammonium salts, for example of perfluorooctanoic acid and omega-hydroperfluorononanoic acid. The amount of these dispersants is generally in the range from 0.01 to 10% by weight, preferably 0.05 to 5% by weight , based on the aqueous medium. In the present invention, it is preferred to use a dispersion stabilizer together with the dispersant in order to improve the dispersion stability of the resulting polymer. Typical compounds for such stabilizers are saturated hydrocarbons with at least 12 carbon atoms. However, when the polymerization reaction is carried out under ionizing radiation, it is expedient to add a saturated hydrocarbon to the polymerization system, which is liquid under the polymerization conditions, in order to prevent the formation of a non-dispersible polymer (by-product) in the vapor phase and also to increase the rate of the polymerization reaction.

6098 47/0934

The polymerization reaction is complete when the concentration of the polymer in the aqueous medium is 25 to 40% by weight ;? has reached. If the concentration of the polymer is above this range, coagulation will occur and a polymer of uniform quality will not be obtained. After completion of the polymerization, the monomers, mainly the TPE _{3, are driven} out of the reactor; the reactor is cooled, whereby an aqueous dispersion of the modified TFE polymer is obtained. When properly diluted with water, coagulated and dried, the dispersion provides a fine powder of the TFE polymer. During or after the coagulation step, the polymer can be granulated by a known method to produce a product which can be conveniently handled.

The invention is explained in more detail below by means of examples in which all parts and percentages are expressed on a weight basis.

The paste extrusion of the polymer is carried out by the following method. The polymer powder (83 parts by weight) is thoroughly mixed with 17 parts by weight of a hydrocarbon stoffgLeitmittels ( "Isoper-E", trade name of Esso Standard Petroleum Co., Ltd., KP. About 125 ⁰ C), which mainly consists of isoparaffin (isopallafin). The mixture is placed in a cylinder with an inner diameter of 31.8 mm, which is provided with a pressing tool at its lower end. The pressing tool has a flattening angle of 30 ° and is provided at its lower end with an opening with an inner diameter of 0.8 mm and a length of 7 mm (land length). The mixture is then extruded from the opening with a piston which moves downwards at a speed of 50 mm / min, the extrusion pressure being automatically recorded on paper. First, the extrusion pressure increases rapidly to a maximum value and then gradually decreases to a constant value in a few minutes. The constant value is measured as the extrusion pressure of the powder. The pressing tool

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has a reduction ratio of 1,600. The powder can be used at different reduction ratios using different Press tools are tested. In the following examples, for example, the extrusion tests are carried out according to this Method carried out at reduction ratios of 36 and 910

Example 1 (experiments 1 to 9)

15 l of deionized, deoxidized water and 750 g of paraffin wax were placed in an autoclave with a V / water capacity of 40 l _5, a stirrer and a temperature regulating jacket. Ammonium perfluorooctanoate, which served as a dispersant, and disuccinic acid peroxide (hereinafter referred to as "DSP"), which served as a polymerization initiator, were also added to the autoclave in the amounts shown in Table 1. The inner atmosphere of the autoclave was displaced several times by gaseous nitrogen, the temperature being set to the value given in Table 1. Thereafter, TPE was added to the autoclave until the internal pressure reached 8.0 kg / cm (gauge pressure). At the same time, chlorotrifluoroethylene (hereinafter referred to as "CTPE") was added in the amounts shown in Table 1. One hour after the addition of DSP, ammonium persulfate (hereinafter referred to as "APS") in the amount shown in Table 1 was added to the mixture while stirring the mixture. The addition of APS started the polymerization substantially and the pressure began to decrease. as

When the internal pressure dropped to 7.0 kg / cm (gauge), TPE was added to the autoclave until the pressure rose to 8.0 kg / cm (gauge). In this way, the reaction system was pressurized repeatedly when a pressure drop was observed. CTPE was added to the system in the amounts shown in Table 1 when the system was pressurized with TPE for the 50th time (on two trials only) and the 63rd time. The time instants at which CTFE was added in between, corresponding to the instants in which about 70 wt -.% And about 85 wt -.% Of the polymer based on the amount of

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polymers ultimately formed had been formed.

The polymerization reaction was stopped when the pressure decreased after the system was pressurized for the 71st time. When the gas in the autoclave was examined by gas chromatography at the end of the polymerization, GTFE was found in a sufficient amount of more than 0.01 'Ao 1% .

The same procedure outlined above was repeated for Runs 1 through 9 to make TFE polymer dispersions with the concentrations given in Table 2. The average particle size of the polymers measurements were carried out in the dispersions, the results also being given in Table 2.

Each dispersion was coagulated to produce a powder, washed and dried, following an IR analysis for determination the CTFE content of the polymer, the results being given in Table 2.

The powder was tested for paste extrusion processability at reduction ratios of 36, 910 and 1600. The results are given in Table 2. In addition, the extrudates were produced at a constant extrusion pressure were obtained, examined for their appearance. The results evaluated according to the following criteria are also the same given in Table 2.

A: extrudate with a smooth surface without warping; B: extrudable with slight distortions; C: extrudate with fragments or distinct warps.

Table 2 shows that all of the polymers made by the above method had satisfactory paste extrusion processability because they are extrudable at moderate pressures and products with uniform properties deliver.

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Comparative example 1 (experiments 10 to 14)

Under the same conditions as in Example 1, TPE underwent emulsion polymerization without any modifier subjected (Trial 10); or modifying agent was used, but the modifying agent could be extreme Coating of the particles are incorporated in a much smaller amount than is provided according to the invention (experiments 11 and 12); or the modifier got only into the cores of the particles and essentially not into the shells incorporated (experiment 13); or hexafluoropropylene (HFP) was used as a modifier instead of CTPE (experiment 14) used.

The polymerization reaction was carried out under essentially the same conditions as in Example 1 with the exceptions carried out, which are given in Table 3. In the experiment it was found that the residual gas in the autoclave at the end of the polymerization contained 0.001 mole SS CTPE. In experiment 14 hexafluoropropylene was used as a modifier according to the method of US Pat. No. 3,142,665.

Table 4 shows the paste extrusion processability of the resulting Polymers which require high extrusion pressures. Experiments 10 to 12 were discontinuous Extrudates at a reduction ratio of 1600 with very fluctuating, largely varying extrusion pressures obtain. The powder of test 14 required - although it could be extruded at all of the reduction ratios mentioned was - a very high extrusion pressure, and the extrudate obtained at a reduction ratio of 36 possessed poor strength, a tendency to break and poor handleability.

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^ equivalent game 2 (attempts I'd up to 17)

TFE was made under the conditions of Table 5 in the same Polymerized manner as in Example 1 with the exception that a 1.5 liter glass reactor containing 750 ml of water was used and that in the experiment 15 TFE was added to the reactor only 24 times. The resulting polymer was smaller in size Particle sizes than those of the previous examples, as can be seen in Table 6.

In experiments 16 and 17, an aqueous dispersion, containing 25 g of modified TFE polymer obtained in Run 15 in the same as noted above Given reactor. TFE was added to the reactor 46 times; the polymerization was carried out under the conditions of Table 5 carried out in the same way as in Experiment 15.

The polymers obtained in experiments Ib and 17 were tested for their extrusion processability with the results of Table 6.

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Table 1
Polymerization conditions

Ver Folymerization APS
(S) Temp. Disper Modifi Amount of modifier used 0.100 search
(At
game
1) initiator 0.15 (° c) greed
middle
(G) ornamental
middle begin
(Mole) Intermediate time
Time (56) amount (mole) 0.100 1 DSP
(G) 0.15 85 23 CTPE 0.010 85 0.050
0.050 2 1.50 0.15 85 23 CTFF 0 85 0.200 3 1.50 0.10 85 23 CTFE 0.010 70 1,000 4th 1.50 0.10 85 23 CTFE 0.020 85 0.500 O
CO 5 1.00 0.15 85 25th CTFE 0.100 85 0.500 CO 6th 1.00 0.15 85 23 CTFE 0.050 35 0.250
0.250 ** · 7th 1.50 0.15 83 23 CTFE 0 85 0.050 O 8th 1.50 0.15 83 23 CTFE 0.050 70
85 CO
CO
■ tv 9 1.50 87 23 CTFE 0.050 85 1.50

Tabel

attempt
(Example
D.

product

Conc. Avg. Modified) mean particle size (ium) hold

'(Weight Si)

Paste extrusion

Extrusion pressure (kg / cm)

Reduction-Reduction-Reduction Ratio Ratio ratio 910 1600

Exterior

of

Extrudate

CD
O
CO

1
2

31.7 33.0

31.1 33.0 31.0 31.0 31.0 31.0 32.0

0.260 0.290 0.261 0.240 0.205 0.225 0.280 0.230 0.246

0.17 0.15 0.18 0.33 1.71 0.85 0.77 0.86 0.08 18.7
17.8
18.4
17.0

17.4

400
380
410
38O

3 ^ 5
360
330
365
460

560 530

567

510 500 505 480 500 650

A A A A B A E A A

Table 3

Experiment (comparative example D.

Polymerization conditions

Polymerization initiator

DSP

Temp,
( ⁰ C)

Dispersant (g)

Modifier

Amount of modifier used

Start (mole)

Intermediate point in time

Time {%) amount (mole)

CD O CO OO

10 11 12 13 14

.1.0 1.5 1.5 1.5 1.5

85
35
85
85
85

23 23 23 22

23

CTPE CTPE CTFE HFP

0.010 0.100 0.010

85 60

62

O I. 0.003 Μ · 0.1 ι 0 0.170

CD Q

OQ

Table 4

Trial (comparative example 1)

product

Conc. Avg.

{%) Particle size (µm)

Codifying agent content (wt. %)

Paste extrusion

Extrusion pressure (kg / cm)

Reduction-Reduction-Reduction Ratio Ratio ratio
910 1600

Exterior of the extrudate

co 10 OO 11 12th O
co 13th co 14th

32.6 0.290 0 20.9 905 Broken C. 31.0 0.290 0.005 - 800 Il C. 30.8 0.240 0.170 21.2 710 t! C. 31.3 0.208 0.170 26.7 850 It C. 30.0 .0.195 0.104 25.1 588 780 A.

cn ro

CD K)

OO

Table 5

Polymerization conditions

attempt
(Ver
equal
example
2) Polymerization
initiator APS Temp.
( ⁰ C) Disper
greed
middle
(G) Modifi-
ornamental-
md ttel Amount of used
Modifier 15th DSP
(G) 0.10 85 1.5 CTPE Start intermediate time
(Get) 16 0 O ₅ O5 85 1.5 - Time (%) amount (mole) 35
O 17th 0 O ₅ Ob 85 1.5 - 0.046-0 CO 0 0 - 0 -C-
-4 0 - 0 '093

Tabel

Trial (comparative example 2)

Product paste extrusion

Conc. Through chn.

{%) Particle size (μΐη)

Modifier content (wt. %)

Extrusion pressure (kg / cm '"')

Reduction-Reduction-Reduction Ratio Ratio ratio 36 910 16ΟΟ

Exterior of the extrudate

O CO CO

O CO OJ

15 16 17

11 , 2 O , 100 ■ 4th , 00 21 O , 312 O , 51 22nd , 0 O , 400 O , 47

819

Broken

C C

CD CD

OO

Test 1

The powders of the polymers in Experiment 4 (Example 1) and in Experiments 10 to 14 (Comparative Example 1) became pipes under the following conditions extruded; the molded articles obtained were tested for their tear strength.

The polymer powders were mixed with 17 parts by weight of a hydrocarbon lubricant (trade name "Isopar-E"), and the resulting mixture was mixed at a rum speed of 40 ^; mm / min and at a reduction ratio of 274 to form a tube with an inner diameter of 6 mm and an outer diameter of 8 mm. The extrudate was continuously sintered at 3Ö0 ⁰ C in an oven, which was connected to the extruder for the production of the finished tube.

A 700 mm long section of the pipe was cut off, one end of the pipe was cut into two parts in the longitudinal direction, and the cut end sections were clamped in the clamps of a tensile tester and pulled apart at a speed of 200 mm / min to measure the tensile strength of the pipe. The results are shown in Table 7.

Table 7

Polymer tear strength (kg / cm ² ) Experiment 4 (Example 1) 4.0

Experiment 10 (comparative example 1) 3 »2

Experiment 14 (Comparative Example 1) 3.1

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Example 2 (experiments 18 to 20)

15 l of deionized, deoxygenated water, 750 g of paraffin wax, which served as a dispersion stabilizer, and 22 g of ammonium perfluorooctanoate, which served as a dispersant, were placed in an autoclave with a water capacity of 40 l, a stirrer and a temperature regulating jacket. The inside atmosphere of the autoclave was replaced with nitrogen gas several times, the temperature was adjusted to 85 ⁰ C. There was TFE in the autoclave

until the internal pressure reached 8.0 kg / cm (gauge). By keeping the temperature at 85 ^° C. with stirring, 1.5 g of DSP and 0.1 g of APS were added to the mixture for starting the

2 polymerization added. As the internal pressure to 7.0 kg / cm

(gauge pressure) dropped, TFE was added to the autoclave until the pressure rose to 8.0 kg / cm (gauge pressure). In this way, the reaction system was pressurized repeatedly when a pressure drop was observed. When the system was pressurized for the 54th time, 0.2 mol of hexafluoropropylene (hereinafter referred to as "HFP") was added. The time was added in between to the HFP in this manner, corresponding to the time when about 72 wt -.% Based on the total amount of the polymer formed at the end of the polymer had been formed. The polymerization was stopped after the system was pressurized 75 times. The remaining HFP gas in the autoclave was determined by gas chromatography; the HFP content of the resulting polymer was calculated from the difference between the determined value and the amount of HFP added. The calculated value for the HFP content agreed with the value which was determined directly by IR analysis of the polymer. The concentration of the polymer emulsion was calculated based on its specific gravity.

Thereafter, the emulsion was coagulated to produce a powder, washed and dried; it was considered in terms of paste extrusion processability at reduction ratios

609847/0934

tested from 910 to 1600.

The same procedure as outlined above was followed was repeated, except that the amounts of the polymerization initiator and the dispersant, the Polymerization temperature, the type and amount of modifier and the time of the addition of the modifier according to Table O were varied. Table 9 shows the properties and paste extrusion processability of the polymers obtained. The modifier used for Experiment 20 is omega-hydroperfluorobutene, referred to as "omega-HB" in Table B.

Table 9 shows that the modified TPE polymers at Reduction ratios of 910 and 1600 under relatively low Extrusion prints are extrudable and provide satisfactory molded articles. A low extrusion pressure means that the ratio of the amount of lubricant (Isopar-E) to the polymer can be reduced.

Comparative Example 3 (Experiments 21 to 22)

Modified TFE polymers were made using the same reactor as in Example 2 under the same conditions as in Example 2 with the modified conditions which are given in Table 8. Specifically, for Run 21, the same amount of modifier was used as for the experiment lo in the system at the beginning of the polymerization added without later addition of a modifier. For Run 22, the same amount of modifier was used as for Run 19 was added to the system after 60% by weight of the TFE to be polymerized had been polymerized, instead of add the modifier at the beginning of the reaction.

The paste extrusion processability of the obtained polymers is shown in Table 9, which shows that it is high

60984.7 / 0934

1620284

Require extrusion prints and extrudates with poor quality Deliver exterior.

609847/0934

Table 8

Polymerization conditions

attempt
(Example
2) Polymerization
initiator APS
(G) Temp. Disper
greed 85 Modifi
ornaments Amount of used
Modifier Intermediate time
Time (%) amount
(Mole) 0.20 I.
ro ·. 18th DSP
(G) Cg) 90 begin
(Mole) 0.04 I. <7> 19th 85 0.10 I. O
CO
oo 20th 0.1 72 -α attempt
(Comparative
example 3) 1.5 0.4 22nd 85
88 IiPP 0 80 0.04 O 21
22nd 4.0 0.1 20th HF ¹ P 0 90 approx
* · » 1.0 22nd omega-HB 0 0.1
0.4 60 1.5
4.0 ro ro
ο ro HPP
HPP 0.2
0

CD N> OO

Table 9

product

Paste extrusion

O CD OO

O CD Ca>

Conc.

avg. Particle size (µm)

Modifier content (weight?)

attempt
(Example 2) 33.5 0.281 18th 33.2 0.286 19th 33.0 0.225 20th attempt
(Comparative
example 3) 34.0 0.170 21 33.2 0.292 22nd

Extrusion pressure (kg / cm * ¹ )

Reduction-reduction ratio ratio 910 1600

0.115 0.007 0.01

320 410 365

400 504

0.198 0.007

at least 1000

520

not extrudable

590

Exterior

of

Extrudate

A A A

cn ro

CD

^{+ determined} after a gas chromatographic analysis of the gas in the autoclave.

The other modifier content values were obtained directly from IR analysis of the FolymgJDen certainly.

Example 3 (Trials 23 and 24) Trial 23

There were 15 l deionized, deoxygenated Water j 750 g paraffin wax, which acts as a dispersion stabilizer and 22 g of ammonium perfluorooctanoate, which served as a dispersant, in an autoclave with a water capacity given by 40 1, a stirrer and a temperature regulating jacket. The internal atmosphere of the autoclave was Replaced several times with gaseous nitrogen, whereby the temperature was regulated. Eventually, TPE was in the Autoclave until the internal pressure reached 8.0 kg / cm (gauge); the temperature was adjusted to 85 ° C. Simultaneously with the addition of TFE, 0.013 mol of KPP was added to the autoclave.

By keeping the temperature always at 35 ^° C. with stirring, 1.5 g of DSP and 0.1 g of APS were added as polymerization initiators to the mixture to start the polymerization.

give p. When the internal pressure dropped to 7.0 kg / cm (overpressure), TPE was again added to the autoclave until the pressure rose to 8.0 kg / cm (overpressure). In this way, the reaction system was pressurized repeatedly when there was a pressure drop. When the system was pressurized for the 54th Shark, HPP in the amount shown in Table 10 was added to the system. The time was added in between to the HPP in this manner, corresponding to the time when about 72 wt -% polymer had been formed based on the amount of the polymer formed at the end..

The polymerization was stopped after the system had been pressurized to the 75th May, after which the amount of des remaining HPP gas in the autoclave was determined by gas chromatography; the KFP content of the resulting polymer was calculated from the difference between the determined value and the amount of HPP added. The calculated value

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-30- 262028A

agreed with the value obtained immediately by IR analysis of the polymer was determined. The concentration of the polymer emulsion was calculated based on the specific gravity of the emulsion. To determine the average particle size of the obtained polymer, the opacity of the emulsion was measured with a opacimeter utilizing light scattering measured. The particle size was calculated from an equation showing the relationship between turbidity and particle size reproduced 3 which had previously been determined by electron microscopic examinations.

Table 10 shows the conditions of the polymerization reaction. Table 11 shows the properties of the polymer; and Table 12 shows the paste extrusion processability and the pipe molding processability of the polymer. The pipe forming workability was tested by a method shown below. Table 11 also shows the modifier content of the polymer; to do this, iran collected the polymer when the system was pressurized 23 times (corresponding to when the polymerization was about 29 % complete).

Attempt 2k

The same procedure outlined above was followed under the conditions of Table 10 to prepare a modified one TFE polymers except that omega-HB was used in place of HFR. Table 11 shows the properties of the polymer obtained and Table 12 shows the properties Paste extrusion processability and pipe forming processability of the polymer.

Tables 11 and 12 show that the polymers obtained were both in terms of paste extrusion processability as well as pipe forming workability.

609847/0934

Comparative example 4 (experiments 25 and 26)

Modified TFE polymers were made using the same reactor as in example 3 under the same conditions as in example 3 with the different conditions manufactured according to table 10. In particular, in Experiment 25, the same amount of humectant was used as in Experiment 23 (Example 3) Added to the system when 72% by weight of the TFE to be polymerized had been polymerized without a modifier was added at the beginning of the reaction. For Experiment 26, 0.2 moles of HFP were added to the system at the start of the Polymerization added without a modifier thereafter was added.

Tables 11 and 12 show the paste extrusion processability and the pipe molding processability of the obtained polymers. The pipe forming processability was determined according to the same method as in example 3 tested. It can be seen that the reaction system to which no modifier was added at the beginning of the reaction, yields a polymer, this in terms of paste extrusion processability, but not in terms of pipe forming processability satisfied. Furthermore, provides a method in which the modifier is combined at the beginning of the reaction without subsequent addition will ,. a polymer with a significantly inferior paste extrusion processability, so that there is no coherent pipe due to breaks occurring during extrusion can be obtained.

The pipe-forming processability of the polymers was after tested using the following method.

83 parts by weight of polymer powder were mixed with 17 parts by weight of lubricant; the mixture was poured into an extrusion cylinder with a die for extruding a pipe with an outer diameter of 2.5 mm and an inner diameter of 1.5 μ given a reduction ratio of 910.

609847/0934

Much like in the extrusion test, the piston for extruding a pipe was detected, the extrusion pressure being automatically recorded on paper. The Lxtrudat vrurde out for 3 minutes by an electric furnace at 330 ⁰ C under no load; the sintered tube was then cooled in air. The inside diameter and the shrinkage of the pipe in the extrusion direction were measured.

609847/0934

'i'abelle IC

Folyüier-i sat ions bedinfunpen

Polymerisation

initiator

DlT ⁵ λΖΓΓ

V Yy 1 V iV /

Temp. ( ⁰ C)

Pressure ₀ disper- / iodifi-]>. Enp; e of the used

(kf / crn ¹ -, fier- ornamental il odifying agent

^ÜD ^ ^r "m ± tteX medium _gtart Intermediate point in time

pressure)

(Mole)

Time (Si) r-feriRe (mol)

cn
ο
co

attempt
(Example 3)

23 1

1.0

22nd HFP Ü , 013 72 22nd omega- O , 005 90

0.190 U,

attempt
(Comparative example A)

25 1
2G 1

ο τ

22 22

HPP

0 0.200

72

0.190

Tabel

σ> ο co οο

ca ■ *> ■

product

Kon ζ. (%) avg. Modifying

Particle average content

size (um) 'of the whole

'Polymers

(Wt%)

attempt
(Example 3) 34.0 23 33.0 24 attempt
(Comparative
example 4) 34.1 25th 34.0 26th

Modifier free of the polymer

2Q % polymerization (wt.-ft)

0.230 0.225

0.270 0.170

0.112 0.010

0.101 0.193 0.004 0.001

0
0.075

Modifier content of the polymer obtained, as 29 wt .- # des
polymers ultimately formed had been formed

attempt
(Example Paste extrusion attempt
(Comparative
example 4) 520 Table 12 (kg / cm ² ) Pipe forming .. final shrinkage I. 23 Extrusion printing 25th at least
1000 Reduction
ratio 1600
(Rod extrusion) Exterior of the Inside
knife (mm) in extru-
sionsrich * ·
tion {%) VJI
I. 24 Reduction
ratio 910
(Pipe extrusion) 26th Extrudate 485 1.47 23.1 60! 570 5O4 Well 1 * 50 25.5 CO 600 dd 420 1.54 30.1 O at least
1000 »T - ⁺ bad
(broken)

The extrudate was broken and did not provide a coherent tube,

Claims (11)

Claims \ y. Process for the polymerization of tetrafluoroethylene with a copolymerizable modifier in an aqueous medium with a content of Fclyn crisis initiator and dispersant for the production of a modified tetrafluoroethylene polymer with a content of 0.001 to 2 wt , (1) that there is at least one compound from the formula CBV = CF (CF ₀ CF-J H, in which η is an integer from 1 to 5) as a codifying agent that can be polymerized into the unit. formed group used unü (2) that at least 50 weight lS, introducing the copolymerisable modifier which is incorporated into the polymer in the polymerization system after 70 weight -% of the formed have been formed at the end of the polymer, and that at least 50 wt.. - % of the copolymerizable modifier incorporated into the polymer is provided on the periphery of the particles of the polymer. 2. The method according to claim 1, characterized in that - after 90 wt .-% of the polymer formed at the end have been formed - the concentration of the copolymerizable modifier at at least 0.01 mol $ based on the total amount of tetrafluoroethylene and the modifier holds in the polymerization system and that in the outermost region of the particles of more than 10 wt -% equivalent of the finally obtained polymer, the copolymerizable modifier provides at a concentration of at least 0.01 mol $.. 3. The method according to claim 1, characterized in that at least 0.001 wt .- $ introduces the copolymerisable modifier into the polymerization system before 30 wt -.% Formed of the polymer formed at the end 609847/0934 and at least 0.001 weight percent of the mis-dhpolymerizable Modifier based on the weight of the polymer formed on the tnae in the core area of the particles of the Provides polymers. 4. The method according to claim 1, characterized in that that the copolymerizable modifier used is chlorotrifluoroethylene used. 5. The method according to claim 1, characterized in that that the copolymerizable modifier is hexafluoropropylene used. L. Process according to Claim 1, characterized in that omega-hydroperfluoroolefin of the formula CP ₂ = CF (CF ₂ CF ₂ ) H, in which η is an integer from 1 to 5, is used as the copolymerizable modifier. 7. The method according to claim 2, characterized in that that the copolymerizable codifier is chlorotrifluoroethylene used. ü. Process according to Claim 2, characterized in that omega-hydroperfluoroolefin of the formula CF ₂ = (CF ₂ CF ₂ ) H, in which η is a whole number from 1 to 5, is used as the copolymerizable modifier. 9. The method according to claim 3, characterized in that that chlorotrifluoroethylene is used as the copolymerizable moistening agent used. lü. Process according to Claim I _{5, characterized in that CF 2} = CFCF ₂ CF ₂ H is used as the omega-hydroperfluoroolefin 11. Modified tetrafluoroethylene polymer, prepared according to the method according to one of the preceding claims. 609847/0934 BAD OR! GfN _AL