CA2093188A1

CA2093188A1 - Polyurethane molding composition

Info

Publication number: CA2093188A1
Application number: CA002093188A
Authority: CA
Inventors: Harald Kiesel; Jan-Peter Piesold; Franz-Leo Heinrichs
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1992-04-02
Filing date: 1993-04-01
Publication date: 1993-10-03
Also published as: ZA932354B; JPH069868A; EP0563918A1; TW281685B

Abstract

Abstract Polyurethane molding composition Sticking of polyurethane molding compositions to machine parts of processing machines and molds can be reduced if a compound of the formula (R1)n-N-(CH2-CH2-OR2)3-n is added as release agent to the molding compositions.
The release agent is a reaction product of long-chain carboxylic acids, preferably technical grade montanic acid, with amino alcohols.

Description

2 ~
HOECHST AKTIENOE SELLSC~AFT ~OE 92/F 095 Dr. DA/b De~cription Polyurethane molding composition The invention relate~ to a polyurethane molding composition which, in order to achieve better mold releace properties, contains a specific organic amide having increa~ed reeistance to migration.

Both foamed polyurethane molding compositions and polyurethane molding compo ition~ which can be proces~ed thermoplastically have a very severe tendency to stick to machine parts and to the molds. In order to prevent this sticking, use i~ frequently made of externally applied release agents, which are usually sprayed onto the machine part~ or into the mold. In order to provide the plastic components produced with mutual protection against sticking together, the~e component~ are also treated with external release agents.

Since, however, the application of an external release agent signifies an additional and expensive operation, attempts are i.ncreasingly being made to work with so-called internal relea~e agents, which are incorporatedhomogeneously into the polymer matrix. However,~because of incompatibilities, the adver~e effect of unde~ired blooming from the polymer matrix at the surface of the pla~tic component produced arises with thi~ type of release agent. Con~equently, grea~y film~ can form on the surfaces and enable sub equent proce~ing ~tep~, ~uch as, for example, coating, to be carried out only with additional expenditure on cleaning.

It i8 known that all of the relea~e ayent~ di~clo~ed hitherto, for example including conventional montan waxes and low molecular wei~ht fatty acid derivativeq, tend to form depo~its (cf. US 4,889,908). Polyethers, which can be obtained by reacting a sub~ituted 1,2-epoxyalk~ne with a polyol~ have therefore been proposed as relea~e ~ 0 9 ~ 3 agentY.

The object was now to find release agents which have a good effect and a very low tendency to migration.

It has been found that the object can be achieved by montan wax derivatives which are obtainable by reacting amino alcohols with montanic acids.

The invention therefore relates to a polyurethane molding composition comprising 90 to 99.99~ by weiqht, with respect to the molding composition, of a polymer which ha~ been obtained by reaction of a bifunctional higher molecular weight polyhydroxy compound with a bifunctional chain extender and an or~anic diisocyanate and 0.01 to 10% by weight, with respect to the molding composition, of a compound of the formula ( Rl ~ n~N~ ( CH2-CH2-OR2 ) 3-n r in which the R1s can be identical or different and are a hydrogen atom, a C1 to C1a-alkyl group or the group R3-Co-, in which R3 is an alkyl group having 23 - 35 carbon atoms, the R2s can be identical or different and are a hydrogen atom or the group R3-Co-, in which R3 has the abovementioned meaning, n i~ 0, 1 or 2 and at least one R3-Co- group is present in the moleculeO

The polyurethane molding composition according to the invention comprises a polymer which is formed by reaction of A) essentially bifunctional, higher molecular weight compounds essentially having two active hydrogen atoms and a molecular mass of from 400 to 20,000, preferably higher molecular weight polyhydroxy compounds, ~) es~entially bifunctional chain extenders, ~uch a~
diols or diamines having a molecular mass of from 32 to 399, and C) organic dii~ocyanates, preferably aromatic diiqocyanate~, 3 ~ ~

D ) with the addition of, if appropri~te, ~tabilizer~ and other additives known per se.
Starting components A), i.e. es~en$ially ~traight-chain higher molecular weight compounds having predominantly two active hydrogen atom~, ~uitable for the preparation of the polyurethanes are virtually all essentially straight-chain higher molecular weight compound~ known per se which have about two reactive groups ~uch as hydroxyl, primary and~or secondary amino, 5H, carboxyl 10 and/or other reactive groups, for example hydrazide groups. Such compounds are, for instance, bifunctional hydroxypolyesters, hydroxypolylactones, hydroxypolyethers, hydroxypolythioether~, hydroxypolye~ter amide~, hydroxypolycarbonate~, hydroxy 15 acetals or vinyl polymers containing hydroxyl groups or other end groups or compounds which already contain urethane and/or urea groups. These compound correspond to the prior art and, for example, are de cribed in detail in the literature.

20 These hydroxyl group-containing, higher molecular weight compounds are preferably, for example, polyesterdiols obtained from straight-chain or branched aliphatic and/or cycloaliphatic diols and aliphatic dicarboxylic acids, in particular adipic acid. Higher molecular weight polyamino 25 compounds, preferably having primary aromatic amino groups, can optionally also be used. Particularly prefexred polyols P.) are adipic acid polyester~ or caprolactone diols or polycarbonate-diol~, optionally as a mixture with polyether~.

30 The chain extenders B) to be u~ed are known per ~e and widely described. The~e are in particular low molecular weight polyalcohol~, preferably diols, and diamines, in particular ( cyclo ) aromatic diamines . Diamines which may be mention~d are 4, 4-diamino-dicyclohexylmethane, 35 isophoronediamine, ethylenediamine and 1, 3- or 1, 4 diaminocyclohexane. Preferred chain extender~ are diols ~93~ 8~

~uch as, for example, ethylene glycol, hexane-1,6-diol and hydroquinone di-~-hydroxyethyl ether, as well as butane-1,4-diol~ optionally in mixtures with other diols, in p~rticular hexan~-1,6-diol~ The molecular mas~ of the chain extender~ i~ from 32 to 399.

In addition, it is possible to u~e monofunctional compounds as ~o-called chain terminator~, in amount~ of from about 0.01 to 3% by weight, with re pect to PU
solid. Examples are monoalcohols, such as butanol, 2-ethylenehexanol, isobutanol, l~octanol, and 3tearylalcohol, or monoamines, such as aniline, dibutylamine, N-methylstearylamine or piperidine.

Dii~ocyanates C) to be used are the aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic diisocyanate~ of the prior art known per se. Preferred diisocyanates are hexamethylene diisocyanate, i60phorone diisocyanate, naphthylene 1,5-diisocyanate, tetramethyl-xylylene diisocyanate, 3,3-dimethyl-4,4-diisocyanato-diphenyl (TODI~, 1,4-diisocyanatobenzene and the corresponding hydrogenated product, toluylene diisocyanates and, in particular, the diphenylmethyl diisocyanate isomers and the corresponding hydrogenatsd products. 4,4-diisocyanatodiphenylmethanP or the mixture of it~ isomers may be mentioned. The said diisocyanate~
can optionally be used together with a polyisocyanate of higher functionality; the amount of the polyi~ocyanate of higher functionaliky must, however, ~e ~o restricted that a polyurethane ela~tomer is obtained which iB ~till meltable or thermoplastic. Example~ of i~ocyanates of higher functionality and monofunctional compounds are al~o described in the literature. Examples which may be mentioned are monoamine~, such a~ butylamine or dibutylamine, hydroxylamine, ~tearylamine, N-methylstearylamine, pyrrolidone or tetrahexylamine or butanone oxime, and al o monoalcohol~, such a~ l~butanol, 2-ethyl-1-hexanol, 1-dodecanol, i~obutanol or t-butanol, cyclohexanol or ethylene glycol monomethyl ether.

Catalysts which can be used are, for example, tertiary amines or organic metal compounds, in particular organic tin, lead and titanium compounds, for example tin(II) acetate, tin(II~ ethylhexoate, dibutyltin dilaurate or lead acetate.

The amounts of reactants A~ to C) for the polyurethane3 are a3 a rule 80 cho~en that the NCO/OH equivalent ratio of isocyanate to OH compounds is between 0.9 and l.2.

In addition to the polymer, the polyurethane molding composition according to the invention contain~, as release agent, a compound of the formula ( Rl ) n~N~ ( CEI2-C~12-OR2 ) 3-n ~
in which the Rls can be identical or different and are a hydrogen atom, a C1 to Cl3-alkyl group, preferably a hydrogen atom, or the group R3-Co-, in which R3 is an alkyl group having 23-35, preferably 27-31 carbon atoms, the R2s can be identical or different and are a hydrogen atom or the group R3-Co-, in which R3 has the abovementioned meaning, n is 0, 1 or 2, preferably 1 and at least one R3~Co- group is present in the molecule. The R3-Co- group i~ preferably the radical of a technical grade montanic acid which has been obtained by oxidative bleaching of crude montan wax and i8 a mixture of C24-C36-carboxylic acids with the emphasis on C28-C32 and contains about 15% by weight of dicarboxylic acids.

The compound~ to be used according to the invention are prepared by reacting C24-C36-carboxylic acids, preferably technical grade montanic acid, with amino alcohol~ of the formula ( Rl ) n~N~ ( CEi[z-CHz-OH ) 3-n in which Rl and n have the abovementioned meanings, in accordance with conventional esterification and amidation method~.

~3~

Suitable amino alcohols are ethanolamine, diethanolamine, triethanolamine and the alkyl derivatives thereof.
Suitable C24-C36-carboxylic acids are, for example, tetracosanoic acid, cerotic acid, montanic acid and melissic acid, preferably technical grade montanic acid which has been obtained by oxidative bleaching of crude montan wax and is a mixture of C24-C36-carboxylic acids with the emphasis on C2~ ~o C3~ and contains about 15% by weight of di~arboxylic acid~.

~he compounds ~re waxy bodie~ which have drop points of from about 60 to 120C.

The polyurethane molding composition according to the invention comprises 90 to 99.99, preferably 97 to 99.9%
by weight of the polymer and 0.01 to 10, preferably 0.1 to 3.0% by weight of the release agent to be used according to the invention.

In addition, the polyurethane molding ~omposition can contain antioxidants, light stabilizers, metal deactivators, stabilizers, propellants, fillers, reinforcing agents, lubricants, pigments, fluorescent brighteners, flame retardants or antistatic agents.

Mixing of the release agents according to the invention into the polyurethane moldin~ composition is effected in the manner customary in pla~tics proces~ing, for example by mixing the compounds and, optionally, further additives into the melt prior to shaping. Incorporation can also be effected by applying the dissolved or dispersed compounds directly onto the polymer or by mixing into a solution~ suspension or emulsion of the ~0 polymer, allowing the solvent to evaporate ~ubsequ0ntly, if appropriate. The use of extruders or kneaders for compounding or physical mixing, for example in slow-speed mixexs, i~ also possible.

~ o ~

The following examples are intended to illu~trate the pre~ent invention.

Example 1 Reaction of technical grade montanic acid with diethanolamine in a molar ratio of 2.25-1 The technical grade montanic acid was introduced into a reactor and melted under an N2 atmosphere. The diethanolamine was metered in at a temperature of 90 to 100C. The mixture was heated to 140C and ~tirred at this temperature until the acid value had fallen below 15 mg KOH/g. The melt was then cooled and ground.
Drop point about 82C; acid value about 12 mg KOH/g;
saponifisation value about 135 mg KO~/g; drawing hardness about 550 bar.

lS Example 2 Reaction of technical grade montanic acid with tallow fat diethanolamine in a molar ratio of 1.6:1 The technical grade montanic acid was introduced into the reactor and melted under an N2 atmosphere. The tallow fat diethanolamine (Rl = radical of tallow fatty alcohol) was addPd slowly to the hot melt~ which wa~ at a temperature of 90 to 100C. The mixture was then heated to 140C and stirred at thi~ temperature until the acid value had fallen below 15 mg KOH/g. ~he melt wa~ then cooled and ground.
Drop point about 75C; acid value about 12 mg KOH/g;
~aponification value about 100 mg KO~/g; drawing hardnefis about 60 bar.

~ ~ 9 ~ 3 Example 3 1 mm shee~s having dimen~ions of 60 x 60 mm were prepared for the migration teQt; plasticizing and homogenization were carried out using a kneader and the subsequent shaping was carried out u~ing a press. The ~pecimens thus obtained were freely suspended in a circulating air oven and conditioned for 24 h at 100C. After this 24 h, the specimens were evaluated according to the criteria of "visible" and "discernakle" deposit.

For characterization of the relea~e action, the release characteri~tics of 1 mm sheets on ~teel sheet~ were assessed. To this end, the specimen obtained after a pressing operation (150C, 100 bar, 180 B) was manually pulled off from the inserted steel ~heet. The evaluation was subjectively determined and classified in accordance with a compari~on ~cale.

The polymer used was a polyester-polyurethane having a Shore A hardness of 93 and a density (23C) of 1.19 g/cm3 and a polyether-polyurethane having a Shore A hardness o 85 and a density (23~C) of 1.12 g/cm3.
The results are summarized in the following table.
Specimens:
1 mm pressed sheets, additive addition 1%
Migration tests after 24 h at 100C, criterium deposit formation ~elea3e action: release characteri~tics o 1 mm sheets from steel ~heet following a preceding pressing operation Table ExPmple Polyester-urethane Polyether-ureth~ne Deposit Release Deposit R21ease formation charact- formation charact-eristics eristics Comp. A none poor none poor Comp. B slight good slight good Comp. C moderate very good moderPte very goDd Comp. D slight good slight moderate 10 Comp. E Rlight moderate slight moderate Ex. 1 none good none good Ex. 2 none good none good Comparison A: Without additive Comparison B: Ethanediol ester of montanic acid Comparison C: Ethylenediamide of stearic acid Comparison D: Trimethylolpropane ester of montanic acid Comparison E: Pentaerythritol eseer of montanic acid Assessment system: none - slight - moderate - severe deposit formation poor - moderate - good - very good release characteristics

Claims

1. A polyurethane molding composition comprising 90 to 99.99% by weight, with respect to the molding composition, of a polymer which has been obtained by reaction of a bifunctional higher molecular weight polyhydroxy compound with a bifunctional chain extender and an organic diisocyanate and 0.01 to 10%
by weight, with respect to the molding composition, of a compound of the formula (R1)n-N-(CH2-CH2-OR2)3-n, in which the R1s can be identical or different and are a hydrogen atom, a C1 to C18-alkyl group or the group R3-CO-, in which R3 is an alkyl group having 23 - 35 carbon atoms, the R23 can be identical or different and are a hydrogen atom or the group R3-CO-, in which R3 has the abovementioned meaning, n is 0, 1 or 2 and at least one R3-CO- group is present in the molecule.

2. The polyurethane molding composition as claimed in claim 1, wherein R3-CO- is a radical of technical grade montanic acid, which is formed on oxidative bleaching of crude montan wax and is a mixture of C24 to C36-carboxylic acids with the emphasis on C28 to C32 and containg about 15% by weight of dicarboxylic acids.

3. The polyurethane molding composition as claimed in claim 1, which additionally contains antioxidants, light stabilizers, metal deactivators, stabilizers, propellants, fillers, reinforcing agents, lubricants, fluorescent brighteners, flame retardants, pigments, colorants or dyes.

4. A process for reducing sticking of polyurethane molding compositions to the processing machines by adding a release agent, wherein from 0.01 to 10% by weight, with respect to the molding composition, of a compound of the formula (R1)n-N-(CH2-CH2-OR2)3-n, in which the R1s can be identical or different and are a hydrogen atom, a C1 to C18-alkyl group or the group R3-CO-, in which R3 is an alkyl group having 23 - 35 carbon atoms, the R2s can be identical or different and are a hydrogen atom or the group R3-CO-, in which R3 has the abovementioned meaning, n is 0, 1 or 2 and at least one R3-CO- group is present in the molecule, is added to the polymer.

5. The process as claimed in claim 3, wherein a compound is added, in the molecule of which, R3-CO-is a radical of technical grade montanic acid, which is formed on oxidative bleaching of crude montan wax and ic a mixture of C24 to C36-carboxylic acids with the emphasis on C28 to C32 and contains about 15% by weight of dicarboxylic acids.