DE1025618B - Process for the production of rubber-like moldings - Google Patents

Description

GERMAN

In British Patent 553 733 there are processes for making rubber-like substances by reaction of polyesters or polyester amides with organic polyisocyanates and in the German patent 838 652 Process for the production of crosslinked plastics described. These are linear polyesters reacted with excess diisocyanate and the free isocyanate groups then with polyfunctional Compounds saturated and, before the final deformation, small amounts of polyfunctional isocyanates incorporated. The final design must be carried out immediately after this additional polyisocyanate has been incorporated will.

These prior art processes have the disadvantage that during the second conversion stage, when the low molecular weight products are mixed with the polyisocyanates, due to the at Mixing process occurring high temperatures a premature reaction can occur. This can lead to a premature vulcanization or scorching of the mixture, also cause the mixture to fail is more plastic enough to be pressed into a uniform molded body. In addition, the mixture gradually become tougher and more difficult to deform during storage.

It has now been found that these disadvantages can be avoided or reduced if one of the mixture adds a substance which reacts with the polyisocyanate to form a thermolabile addition compound. In this way one avoids the previous preparation of the addition compound.

The method according to the invention for the production of rubber-like substances consists of a two-stage process Reaction of a polyester or polyester amide with a polyisocyanate or mixtures of these substances, wherein in the first reaction stage, in a known manner, only such an amount of polyisocyanate is used that is sufficient to produce a low molecular weight polymer that is suitable for processing on a Rubber mixing roller and suitable for longer storage, while in the second stage an additional amount of polyisocyanate and also a substance which reacts with the polyisocyanate to form a thermally unstable addition compound is added.

The reaction of the polyester or polyester amide with the polyisocyanate and the selection of the reactants to be considered for this can be carried out according to the state of the art. The polyesters or polyester amides can therefore be prepared by condensing one or more dicarboxylic acids with one or more bifunctional hydroxyl or amino compounds. Acids that can be used are aliphatic dicarboxylic acids, such as succinic acid, glutaric acid, adipic acid, alkyladipic acid, azelaic acid and sebacic acid, or aro-production process
rubber-like molded body

Applicant:

Imperial Chemical Industries Limited,
London

ίο Representative: Dipl.-Ing. A. Bohr, Munich 5,

Dr.-Ing. H. Fincke, Berlin-Lichterfelde, Drakestr. 51,
and Dipl.-Ing. H. Bohr, Munich 5, patent attorneys

Claimed priority:
Great Britain October 22, 1954 and October 5, 1955

Philip Cowey Johnson and Henry George White,
Blackley (UK),

have been named as inventors

matic dicarboxylic acid such as phthalic acid, isophthalic acid and terephthalic acid can be used; aromatic However, acids are generally only of value when they are more aliphatic together with larger molar amounts Acids are used. As bifunctional hydroxyl or amino compounds e.g. Ethylene glycol, 1,2-propylene glycol, butane-1,3-diol, butane-1,4-diol, Diethylene glycol, monoethanolamine, hexamethylenediamine and benzidine into consideration.

Those for the reaction with the polyesters or polyester amides The polyisocyanates used in the known first process stage are, in particular, aliphatic Diisocyanates such as hexamethylene diisocyanate and aromatic diisocyanates such as diphenylmethane-4,4'-diiso ~ cyanate, S.S'-dichlorodiphenylmethane-l ^ '- diisocyanate, diphenyl-4,4'-diisocyanate, Diphenyl ether 4,4'-diisocyanate, naphthylene - 1,5 - diisocyanate, m - phenylene diisocyanate, p-phenylene diisocyanate, tolylene diisocyanate and monochlorophenylene-2,4-diisocyanate.

The first process stage is advantageously carried out in a vessel provided with a stirrer or in one for mixing viscous plastic masses suitable mechanical mixer performed.

It is advantageous to minimize the ingress of atmospheric moisture to the mixture. The mixture of polyester, polyester amide and polyisocyanate is heated according to an expedient method advantageously to a temperature in the range from 120 to 170 °, until the determined from time to time Williams plasticity number of the mass no longer increases.

709 908/440

The measurement of the Williams plasticity number is in British standard specification No. 1637 (British standard Institute, London). The addition of diisocyanate is chosen so that the maximum when heated Williams plasticity number achieved is between 200 and 550, preferably from 300 to 450. The for this The amount required is usually so large that for each isocyanate-reactive terminal group des Polyesters or polyester amides 0.9 to 1.5, generally work dried on a two-roll mill at 140 ° C, then chilled and poured on cold mixing rolls with 3.15 parts of finely ground mercaptobenzothiazole for 4 minutes mixed. 4 parts of naphthylene-1,5-diisocyanate are used and distribute them intimately in the mixture.

This mixture can be milled on the mixing roller for an additional 150 minutes before it scorches and thereby falls off the rollers, while a similarly produced without the addition of mercaptobenzothiazole

1.0 to 1.3 isocyanate groups are necessary. The mixture produced is scorched after just 27 minutes. To

The reaction product retained and used according to the method can be processed on a rubber mixing roller and under normal storage conditions without any noticeable change in its workability for many months keep for a long time.

In the second process stage claimed according to the invention, this low molecular weight product is mixed with a further amount of a polyisocyanate. This polyisocyanate can either be one of the other methods for determining the scorching using the Mooney plastometer (British Standard No. 1673, Part 3, Section 1, 1951) scorches the mixture with mercaptobenzothiazole in 28 minutes at 110 ^° C., while without mercaptobenzothiazole all other things being equal, a scorching time of 10 minutes is measured.

The mixture containing mercaptobenzothiazole can be satisfactorily made into skins or other

be those polyisocyanates that compress and vulcanize products molded in the first process, level have been applied, or you can e.g. with the mixture below 18 days before vulcanization work with an aromatic triisocyanate such as triphenylmethane-4,4 ', 4 "-triisocyanate. At this stage

the other ingredients are mixed in and ground for unvulcanized natural rubber mixtures Manufacture of rubber products can be kept under normal conditions. From the without mercapto

then heats up e.g. in a press. The unvulcanized mixture produced in the second benzothiazole compound

Step required amount of polyisocyanate is usually about 5% of the amount by weight of the low molecular weight intermediate or less. According to the invention, one sets during the second could not be satisfactory in storage under the same conditions as early as 4 days after mixing Shaped body can be obtained more.

The rubber type used in this example

Stage of the process prior to the addition of the polyisocyanate is a ₃₀ diisocyanatmodifizierte polyester is to a known substance that produced with the polyisocyanate a thermolabile way, by forming by a mixture of addition product, by which is meant a compound which not more than one free isocyanate

group contains and when heated to 100 to 180 ⁰ C a 2336 parts of adipic acid and 1115 parts of ethylene glycol in the course of 3 hours with stirring a stream of carbon dioxide passed through, the temperature

Connection sets free, which allows at least two free 35 to rise ^{from 150 to 25O 0 C.} After further contains isocyanate groups in the molecule. Suitable thermally 5 _^1/2 StundenlangemRührenbei250 ° Csind592TeileWasser

Forming substances are distilled off and a waxy product is obtained

with an acid number of 2.7 mg KOH / g and a hydroxyl number corresponding to 61.9 mg KOH / g. 600 parts of this polyester are then ^{stirred for 7 minutes at 140 °} C. with 68.8 parts of naphthylene-1,5-diisocyanate, and the

Substances forming molabile addition compounds are e.g. phenol, succinimide, mercaptobenzothiazole, caprolactam, Phenyl-ß-naphthylamine, diphenylamine and triphenylcarbinol.

The amount of these to be added to the ground material is preferably ^a / ₄ to 2 ^χ / ₂ moles per mole of added in the second stage diisocyanate. If you work with isocyanates which contain more than two isocyanate groups, you can add correspondingly larger amounts of the agent blocking the isocyanate groups.

If one one or more of these substances to the mixture, preferably before or during the addition of the mixture is heated for ₂ hours at 150 ⁰ C I ¹ Z to give a rubbery material at 82.5 ° C a Williams plasticity number of 511 has.

Example 2

100 parts of the diisocyanate-modified described in Example 1 Polyesters are ground by grinding on a two-roll mill for 10 minutes

last portion of the isocyanate added, the
Mixture without risk of toughening for a long time - ^{dried 50 140 0} C, then cooled and rolled in cold mixing rooms under the conditions prevailing in the factory, mixed with 1.8 parts of phenol for 4 minutes, stored. The mixture can also, preferably
below 8O ⁰ C, for example, on a rubber mill or in a high-performance mixing device
Process without the risk of scorching or a premature mixing roller before scorching occurs, reaction thoroughly mixed during the mixing process while the measurement in the Mooney plastometer takes place

Then 4 parts of naphthylene-1,5-diisocyanate are added and intimately distributed in the crowd. A sample of the mixture can be left on for an additional 60 minutes

will.

In the known processes, when using polyisocyanates in the form of addition compounds, which decompose when heated, but to a certain extent hold back the toughening or the scorching. However, the inventive method makes a separate operation for producing the Addition connection superfluous.

HO ⁰ C results in a scorching time of 19 minutes.

The unvulcanized mixture can still be deformed into pelts in a satisfactory manner after 21 days.

Example 3

100 parts of the diisocyanate-modified described in Example 1 Polyesters are dried for 10 minutes by processing on a two-roll mill at 140 ° C.

The invention is illustrated by the following examples, in which the parts relate to 65 net, then chilled and 4 minutes by weight on cold mixing rollers. _w ith 3.8 parts succinimide mixed. Then 4 parts are _. . . Naphthylene-1,5-diisocyanate added and on a

^ice P ^ie mixing roller intimately distributed in the mixture. A sample

100 parts of a rubbery diisocyanatmodifi- the mixture results in a Mooney Plastometer at ed polyester are carried for 10 minutes comparison 70 110 ⁰ C a scorch time of 19 minutes. The un-

Vulcanized mixture can be shaped into good pelts even after 8 days of storage.

Example 4

100 parts of the diisocyanate-modified polyester according to Example 1 are mixed with 4 parts of naphthylene-1,5-diisocyanate and 3.2 parts of diphenylamine, and the mixture is mixed thoroughly on a mixing roll mill. Immediately after mixing, and 28 skins are subsequently vulcanized from this mixture, and long in both cases by 10 minutes compression at 150 ⁰ C. The resistance of the diphenylamine mixture containing, in comparison with a processed in the same manner, but no diphenylamine mixture containing results from the physical test values compiled in the following table.

With
Diphenylamine
vulcanized 28 days Without
Diphenylamine
vulcanized 28 days 0 days 243 OTage 100 Breaking strength (kg / cm ² ) 270 950 323 475 Elongation at break (° / ") ... 1050 104 850 Load at 700 ° / ₀ iger
Elongation (kg / cm ² ) .. 104 214

25th

Example 5

100 parts of the diisocyanate-modified polyester described in Example 1 are mixed with a mixture of 4 parts of naphthylene-1,5-diisocyanate and 2.65 parts of p-nitrophenol and the mixture is mixed thoroughly on a mixing roller. The measurement of the scorch time of this mixture in the Mooney Plastometer at 110 ⁰ C resulting in 32 minutes. A corresponding mixture without p-nitrophenol scorched, as indicated in Example 1, within 10 minutes.

Example 6

Replacing the employed in Example 5 p-nitrophenol by o-nitrophenol, the scorch time of the mixture at 110 ⁰ C is 56 minutes.

Claims (3)

PATENT CLAIMS: 1. A process for the production of rubber-like moldings by the two-stage reaction of a polyester and / or polyester amide with a polyisocyanate, characterized in that the low molecular weight polymer produced in the first stage in a known manner with a deficit of polyisocyanate is mixed with a polyisocyanate to form thermolabile Addition compounds reacting substance, then incorporates further polyisocyanate, deforms the mass and hardens ^{at temperatures above 100 ° C.} 2. The method according to claim 1, characterized in that substances forming the addition compound Phenol, succinimide, mercaptobenzothiazole, caprolactam, phenyl-ß-naphthylamine, diphenylamine and Triphenylcarbinol can be used. 3. The method according to claim 1 and 2, characterized in that one ^{uses of the substance reacting with the polyisocyanate to form a thermolabile addition compound 1} I ₁ to 2 ¹ Z ₂ moles per mole of the diisocyanate used in the second stage. Considered publications:
German Patent Nos. 838 652, 916 225;
»Angewandte Chemie, 64 (1952), pp. 523 to 531. © 709 908/440 2.