DE1795005C3 - Stabilization of a prepolymer with terminal isocyanate groups - Google Patents

Description

The binding concerns the stabilization of \ Orpolymerisaten, which contain unreacted isoeyanai groups. Leave the stabilized prepolymers is particularly suitable for the production of one-component products Two-component reaction products based on polyurethane use when fast-curing products with very high stability are to be obtained.

VorpoKmensjie. the unreacted isocyanate groups contain and isocyanate by reacting an organic PoKoIs with an organic poly have been produced in such quantities, d.ii. '· Isocyanate groups in excess in the prepolymer are often used in the manufacture of polyurethane reaction products. Lin A particular disadvantage of these prepolymers is that they are very reactive or with water are very sensitive to water. Another disadvantage is that the unreacted, extremely reactive isocyanate groups often with the urea and or U ret modules of the Vorpolvmerisate with the formation of different Biuretuml Allophanate derivatives react. These derivatives affect the strength, the stability and the color of these prepolymers produced PoK ureihan products.

To the disadvantages of the terminal Isocvan.itgruppcn to switch off adhering prepolymers. became the isoeyanate groups with a compound. which contains an active hydrogen atom, blocked. This method does solve the problem of responsiveness the isocyanate groups. but the blockage must of the isocvanate groups before the prepolymers are used, especially in paint and Coating compounds based on polyurethane repealed will.

In addition, stabilizers have already been used for prepolymers containing terminal isocvanate groups some of which are effective in suppressing the reactivity of the isocvanate groups. Prepayment. containing these stabilizers, however have not been used for the production of PoK urethane reaction products, because these stabilizers, even in very small amounts, cure those produced in their presence Prevent products completely or inhibit them very strongly, while on the other hand stabilizers, which do not affect the hardening speed, the prepolymers do not have a sufficient shelf life for technical use or Lend useful life, so d;>, ß these must be used shortly after their manufacture, if they opt for coating compounds based on polyurethane should be suitable, hs thus sees a need for terminal prepolymers containing lsoc. \ anate groups. which have increased stability and used in one-component or two-component polyurethane reaction products allow the products to cure quickly without affecting the physical properties of the cured products to affect.

It has been found that this problem has been solved

ίο can be if you üortrilluoiid. preferred in the form of compounds or complexes that are liquid at room temperature, to stabilize a prepolymer obtained by reacting an organic polyisocyanate with an organic polymer oil with terminal isocyanate groups in amounts of about 0.002 to 0.2 percent by weight, based on the solids content of the Vorpoiymerisats. used. This results in stabilized prepolymers containing terminal isocvanate groups obtained, the improved shelf life when used in one-component poly urethane reaction products or usability without significant inhibition of the curing speed of the Products and when used as one component in two component polyurethane reaction products improved service life without deterioration in the rate of aging of the products exhibit.

As liquid compounds or complexes of boron trifluoride. which facilitate its use are ether compounds and complexes of boron trilium chloride preferred those in "Boron Trifluoride and its Derivatives" by Harold Simmons Booth and Donald Ray Martin. Pp. 68 to 71, John Wiley and Sons,

js Inc., New York, 1949. In general, the use of compounds and complexes of the lower ethers is preferred because they introduce higher levels of BF _: , into the compound or complex. The boron trifluoride compounds or complexes of dimethyl ether are particularly preferred. Diethyl ether, methyl ethyl ether or tetrahydrofuran. A suitable product that is readily available. is the commercial product known as boron trifluoride etherate, which primarily consists of the boron trifluoride complex of diethy 1-ether. The boron trifluoride is used in an amount of preferably 0.02 to 0.2 percent by weight, based on the solids content of the prepolymer containing isocvanate. used.

It is already known in the case of the polymerization carried out in the presence of a tertiary amine of compounds with isocvanate groups to use acidic compounds to get the effect of the tertiary amine and interrupt the polymerization. Apart from the fact that boron trifluoride is not mentioned under these compounds. of course also has this procedure nothing to do with the use of boron trifluoride or liquid compounds or complexes in particular of boron trifluoride to stabilize a prepolymer with terminal isocvanate groups. The person skilled in the art also knows from the relevant literature that low concentrations of acids are present in Polyurethanes generally accelerate the chain extension reaction only slightly, at higher rates Concentrations even slow down noticeably, while they react strongly to the crosslinking reaction have a decelerating effect. Surprisingly it was

in contrast to this behavior of acidic avoidance for the stabilized prepol

Applications have been made when using according to the invention, show a much longer period of time

Boron trilluoride found that with such a stahili- period of use again without impairment

ized prepolymers in spite of their "content of the curing rate of the coating compositions

this liquid compound or its complexes 5 or the physical properties of the paints

neither the hardening speed nor coatings. Here, too, the paintings have or

Π Li Ii t will still deteriorate in physical exertions an exceptional resistance to

discoloration can be observed in the end products,

pay attention is a result that could not have been foreseen. In the production of two-component over-

According to the invention, the boron trinuoride and the tensile masses can be produced using the inventive method

preferred liquid compounds and complexes stabilized prepolymers is generally

To stabilize prepolymers, boron trifluoride is used to add the terminal isocvanal groups

«Earth, given aromatic, aliphatic prepolymer when they are obtained, which is then added

liM-he or cycloaliphatic polyisocyanates or one containing terminal hydroxyl groups

the combinations of which were used, namely 15 components and one solvent

Diisocyanates such as m-phenylene diisocyanate. Toluylene is given. However, it is also possible to use the boron

2.4-diisocyanate, hexamethylene-l / i-diisocyanate, tetretritluoride to form a terminal hydroxyl group

meth \ len-1,4-diisoc> anat. To give cyclohexylene-M-diisocva-containing component and then this

nat, Naphthylc-US-diisocyanate, I-Meihox \ phenvlen- mixture with one terminal isocvanal group

2.4-diisocyanate, diphenv.! Methane-4,4'-diisocyanate, 20-containing prepolymer. Further

4.4 '- biphenslene diisocyanate, 3,3' - dimethoxy-4,4'-bi- can be a polymeric isocyanate such as polymethylene

phenylene diisocyanate, 3,3'-dimethyl-4,4'-biphen \ - phenylene isocyanate, containing isocyanate groups

Lene disocvanate or 3.3'-dimethyldiphen> imethane component of the paint or coating

4.4'-diisoc> anat, as well as Triisocyanaie, such as 4,4 ', 4 "-Tri- mass can be used.

phenylmeihandiisocvanat, Polvmethylenpolyphenv- 25 The paints or coatings mentioned

icnisocvanate or toluene-2,4,6-triisocyanate. or mixtures based on polyurethane can be applied to the

iraisücyanate. such as 4,4'-DimethyIdiphenylmethan- various documents by customary methods.

2.2 -fo'-tetraisocyanate. Particularly advantageous because by brushing, spraying or immersing

their ready availability are ^u and their properties moved together applied with solvents

are toluene diisocyanate, diphenylmethane-4,4'-diiso- 30. Furthermore, heated parts for the squeegee

cyanate or polyphenylene isocyanate. application through the powdery coating masses

Can be used as organic polyols in the extraction of the. The coating compositions turned out to be terminal isocyanate groups containing prepoly as particularly advantageous for the production of Merisate are those that have at least two coating compositions for leather or floors. Inactive Contain hydrogen atoms, namely Hv- 35 dem can the most varied of elastomeric overdroxyl groups polyesters containing polyesters, polyveneers are produced from the coating compounds, Polyether polyols, terminal hydroxyl groups, except for coatings or paints, are suitable Retaining polyurethanes, polyvalent polyethioethers, products stabilized according to the invention also for Alkylene oxide adducts of acids of phosphorus, poly sealants or spreading agents. Elastomers or acetal, aliphatic polyols, aliphatic thiols, foams.

finally alkane, alkene and alinthiols with two In the following examples all parts are

or more - SH groups, diamines, namely parts by weight, unless otherwise stated,

aromatic, aliphatic or heterocyclic di-. 11th

amines and their mixtures, as well as compounds, P

containing two or more different groups from 45 A terminal isocyanate group

the classes defined above, such as prepolymer was prepared as follows:

Amino alcohols, which have an amino group and an In a reaction vessel, 626.4 parts of ToIu-

Containing hydroxyl group, or also compounds, ylene diisocyanate and 182 parts of toluene. then

the one - SH group and one OH group was a mixture of 426 parts of a tri

hold or compounds containing an amino group 50 methylolpropane and propylene oxide produced tri-

and a - SH group. ols, which had a molecular weight of 426. 766 part

According to the invention, the stable polypropylene glycol containing a molecular sieve prepolymer can preferably be added to the vessel for the weight of 766, 0.38 parts of lead octoate and the production of paints or coatings, or 1636 parts of xylene, mixtures based on polyurethane 55 where the reaction temperature between 4> and and have, as the following examples show. 60'C was held. After the addition, there was increased stability. Typical one-component Cberman the reaction about 1 hour at about 49 to draw compounds or paints on polyurethane 60 ⁰ C proceed. The Vorbasis thus formed, which under use of the invention for the stabilized polymer prepolymers, the 2.8 °, _'o unreacted isocyanate was cooled to room temperature, made 60 a terminal isocyanate group-containing Vorsind have polymer significantly prolonged inventory levels, speed. In addition, the cure rate was obtained.

abilities of the coating compounds and the physical _rc , .. " _c . ....

_. ,,, * ■. , fs, .. · .. u · Stabilization according to the invention

Properties of the coatings obtained are not affected. ^{E 6 e}

pregnant. Furthermore, the paints and coatings 65 show two comparison samples of 150 parts each of the prepolymer friction material produced in the manner described with an exceptional resistance to discolouration. Typical two-component paints or sats (solids content 50 °; ₀ ) were as follows under coating compositions that were tested in accordance with the invention: No stabilizer was added to part A

Donor Part B included 0.02 percent by weight of boron triiluoride, based on the solids content of the prepolymer, given. The stability of the prepolymers was determined by the viscosity the prepolymerization was measured periodically. The results of this investigation are in Table 1 given.

Table 1

Time, days

10

54

Viscosity at 50 ^E C

1.6

Gel formation
Gel formation

1.6 2.7 2.5 3.9

Physical Properties

Tensile strength, kg / cm ²

Yield strength, kg'cm ²

Module at 100 °, "elongation,

kg, cm ²

Strain. ° ' _o

Elongation at the yield point,%

Tear Strength, kg, 'cm

Dry to the touch in hours.

Dust dry, hours

Dried through, hours

302 278 196 182 188 177 247 205 10 10 2.86 3.04 1.5 2.5 3.5 4.5 7.5 8th

Different amounts of boron trifluoride were given to parts. The stability of the prepolymers was determined by periodically measuring its viscosity.

The results of this determination are given in Table 3.

The values in the table show that the unstabilized prepolymer gelled in 6 days while the prepolymers stabilized according to the invention still essentially: borrowed were stable.

To ensure the effectiveness of the inventively stabilized, prepolymers containing terminal isocyanate groups when used in one-component floor coatings To illustrate, JOO parts of the above prepolymers were 35 parts Diluted toluene and 25 parts of xylene. Coatings were then applied by pouring and through the Hardened humidity. The physical properties of the coatings are shown in Table 2 below called.

Table 2

Table 3 IO Amount of stabilizer in 30th after 6 days ... Λ B. C. £ Weight percent, be after 54 days ... went to the festival 15 material content of the Vor polymers Viscosity in p at 50'C. .. 0.01 0.2 0.4 after 4 days ... 1.6 1.6 1.1 » 1.6 half gelled 1.9 2.0 5.1 gelled 2.2 2.2 7.3 - 5.3 6 ^ 9 gelled

The values in Table 2 show that the physical properties of the stabilized Coatings produced by prepolymer do not deteriorate due to the presence of the stabilizer. More importantly, the cure rate of the coatings was also not affected, as the time to hardening shows.

Example 2

A prepolymer containing terminal isocyanate groups was prepared for the wine described in Example 1 using the same ingredients in the same amounts. The Vorpolyraerisat obtained contained 2.8 ° / ₀ unreacted isocyanate.

Four comparative samples of 100 parts each of the produced Prepolymer were tested in the manner described below. Part Λ served as a comparison post. To the other three

The values in Table 3 show that small amounts of boron trifluoride etherate effectively stabilized the prepolymer, while the unstabilized prepolymer converted to gel within 6 days was. After 2 months, prepolymers 3 and C were still stable.

One component floor coverings have been prepared from the prepolymers mentioned above. As in Example 1, a fast-curing coating composition was obtained without the physical properties of the coatings produced were significantly impaired.

Example 3

A prepolymer containing terminal isocyanate groups was prepared as follows: 382.8 parts of tolylene diisocyanate and 628 parts of toluene were placed in a reaction vessel. A mixture of 170.4 parts of a triol prepared from trimethylolpropane and propylene oxide, which had a molecular weight of 426, 459.6 parts of a polypropylene glycol, which had a molecular weight of 766, 242.1 parts of a condensation product of 2.2- (4, 4'-Hydroxyphenyl) propane and propylene oxide, which had a molecular weight of 538, one part of dibutyltin dilaurate and 628 parts of toluene were then slowly added to the vessel, the reaction mixture being kept between 49 and 60.degree. After the addition was complete, the reaction was allowed to proceed at 49 to 6C / C for about 1 hour. The obtained prepolymer was cooled to room temperature. An isocyanate-terminated prepolymer enthallendes (solid content 50%), which contained 3.2 ° / ₀ unreacted isocyanate was obtained.

Stabilization according to the invention

The prepolymer prepared in the manner described was used in two samples of 250 parts each divided. Some of them did not receive any added stabilizer. The other part was 0.02 percent by weight (based on the solids content of the prepolymer) boron trifluoride added as a gas into the solution of the prepolymer was introduced. The stability of the prepolymer was determined by periodically

distil clic viscosity of the solution was measured. The results of this evaluation are given below mentioned in Tiibcllc 4.

Tiibellc 4

Line. months Viscosity at 24.4 C. Ii Λ 4.4 (i 0 4.94 5.16 1 5.22 5.20 5..Vi MO 6th 8.H0 P.50 12th (jclbildiing in 8 months

The values in this table indicate that, in the case of non-sensitive prepolymers, gel formation within of 8 months occurred, while the prepolymer stabilized according to the invention itself remained essentially stable after one year.

To ensure the effectiveness of the stabilized according to the invention, prepolymer containing terminal isocyanate groups when used in one-component floor coverings To illustrate, 100 parts of the above prepolymers were mixed with 35 parts Diluted toluene and 35 parts of xylene. Then coatings were poured and allowed to cure through Leave humidity. The physical properties of the coatings are given in Table 5.

Table 5

Physical Ligensc adhere

Tensile strength, kg cm-

Yield point, kg cm-

Module "at 100 °" elongation.

kg / cm ⁸

Strain, ".'"

Elongation at the yield point.

Tear strength, kg cm

Sward hardness

after 2 days

after 6 days. . "

finally

393 204

200 210

7 5.57

10 16

338 165

162

214 S 4.57

6 12 16

The values in Table 5 show that the physical Properties of the coatings produced from the stabilized prepolymer as a result of Presence of the stabilizer did not deteriorate. More important is. that also the speed the hardening of the coatings was not impaired, as the values of the Sward hardness indicate.

Example 4

A polyurethane reaction product suitable as a sealant was prepared as follows:

A prepolymer was prepared from 522 parts of toluene diisocyanate and 1535 parts of a trio which had a molecular weight of 1535 and was obtained from trimethylolpropane and propylene oxide using one part of lead octoate as a catalyst. A prepolymer containing terminal isocyanate groups. having the 100 ° "solids and 6.1 ⁰ ₀ Z contained unreacted IsocyanRtgruppen was obtained.

Invention scope stabilization

The prepayment was divided into two equal parts divided, / ti one part was 0.02 percent by weight Boron trifluoride acetate given. Cast from each part Foils cured at the same rate. Stability tests were also carried out by viscosity measurement carried out at 49 ° C. In the case of the unstabilized prepolymer, Gcl formation occurred in-I alh from 6 days. while that according to the invention stabilized prepolymer was still stable after 3 weeks.

Example 5

Two terminal prepolymers containing isocyanate groups, the 4.4 °; _O contained unreacted isocyanate were prepared in the manner described in Example 1 from the following ingredients:

ao parts

PoKäthertriol from Trimethylolpropane
and propylene oxide (molecular weight

426). . . . ' 352.5

Polypropylene Glycol 310.7

"5 toluene." '366.2

Xylene 1100.2

DibuUl / innmercaptide 0.3

HxansethslenendiisoLyanat 803.5

In addition to the above ingredients, 0.9 parts (0.02 percent by weight) of boron trifluoride was used added to the constituents during the production of a prepolymer). The physical properties of coatings made from the two PoK-kidneys and the curing speed the coatings were not affected by the presence of the stabilizer. The freshly made, unstabilized prepolymer exhibited a Gardner viscosity of "E" while that stabilized Prepolymer had a Gardner viscosity of "G". After 2 months it had not stabilized Prepolymer has a viscosity of »L <\ while the stabilized prepolymer has a viscosity of "Ic had.

Example 6

This example illustrates the effectiveness of terminal isocyanate groups stabilized according to the invention containing prepolymers when used for the production of two-component coating compositions based on polyurethane.

Two-component polyurethane coating compositions were made from 100 parts of the described in Example 4 benen prepolymer as a component together with 4.1 parts of Äthylenglykoi as endstän ended component containing hydroxyl groups made ago. One part of the product became 0.02 parti Given boron trifluoride ether. Part of every product

§0 was used for stability tests, the other part as leather Coating used.

Both coating compositions were cured in 8 hours at 76 ° C., a sign that the stabilizer did not adversely affect the curing speed of the polymer. However, the unstabilized Vorpolyinerisat hatt a service life of only 10 minuter while the stabilized prepolymer a Gt life duration of more than 45 minutes hold.

Example 7

This example illustrates the effectiveness of terminal isocyanate groups stabilized according to the invention Enlhaltenden prepolymers when used for the production of two-component polyurethane compositions.

Two-component polyurethane compositions were made from 100 parts of the prepolymer described in Example 4 as a component together with 19 parts of a polyhydric triol from trimethylolpropane and Propylene oxide, which has a molecular weight of 426 had prepared as a terminal hydroxyl group-containing component. Part of the product 0.02 part of boron trifluocide were added. A portion of each product has been tested for stability, the other part used as a cover coating.

Both products were cured in 8 hours at 76 ° C, an indication that the stabilizer was slowing down the cure rate des Polvmcren not affected. The useful life of the unstabilized prepolymer however, it was only 30 minutes while the stabilized prepolymer had a usable life of more than 2 hours.

Example p

A two-component polyurethane-based foot testicle was made using 40.5 parts of a polyether trinl made from propylene oxide and trimethylene propane, which had a molecular weight of 436 and which had terminal hydroxyl groups ; u! c!: u ...:! .. c: ^- ..! - A mixture of 100 parts of the prepolymer containing terminal isocyanate groups prepared according to Example 4 and 51.5 parts of polymethylene polyphylene isocyanate, which serves as a permanent component containing isocyanate groups Boron trifluoride etherate was added, namely 0.1 percent by weight, based on the total solids content of the mixture. The same MasiC was prepared using 0.1 percent by weight of acetyl chloride, which is a common stabilizer. When the masses hardened, the stabilizer was present no negative influence on the hardness rate or the physical properties of the coatings produced Within 2 weeks there was strong discoloration of the coating which had been produced from the coating composition stabilized with ethylene chloride, while the coating which had been produced from the coating composition produced with ßortrilluorid showed no discoloration after 2 months.

> o H c i s ρ i c I 9

This example illustrates the use of a terminal isocyanate group which has been stabilized according to the invention containing prepolymer for the production of polyurethanes by the one-step process. A polyurethane was prepared by reacting X5 parts of a triol from trimethylolpropane and propylene oxide, which had a molecular weight of 1535, with 15 parts of Toluylcndiiso-

ao cyanate in the presence of 0.2 parts of lead octoate. The reaction mixture gelled within 1 minute. The reaction was made using the same ingredients and amounts and with the additional use of 0.02 part of boron fluoride ether repeated.

The reaction mixture remained liquid for more than 10 hours at room temperature. The reaction continued one. when the mixture was heated.

The experiment described above was untci

3η repeated use of 0.2 parts of tin (II) octoate instead of lead octoate. In the unstabilized S., ic -. 'Λ , GJSil.k'.ng occurred within 30 minutes. while the stabilized system more al; Remained stable for 1.5 hours.

The systems described in this example siiu particularly advantageous in cases where it is appropriate is. suppress the urethane reaction for a certain time without reducing the hardness Onset of the reaction to impair. Such cases are found in applications of polyurethane reaction products that require the reaction mixture to pass through relatively narrow passages before use Must be called. and in the manufacture of highly foamed foam blocks.

Claims (1)

Claim: Use of boron fluoride, also in urine of complex compounds that are liquid at room temperature, to stabilize a through Implementation of an organic polyisocyanate with an organic polyol prepolymer obtained with terminal isocvanate groups in amounts of around 0.002 to 0.2 percent by weight, depends on the solids content of the prepolymer sals.