WO1981000715A1

WO1981000715A1 - A method for the manufacture of monocomponent polyurethane foam

Info

Publication number: WO1981000715A1
Application number: PCT/DK1980/000034
Authority: WO
Inventors: B Scholten
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-09-14
Filing date: 1980-06-04
Publication date: 1981-03-19
Anticipated expiration: 1982-03-14
Also published as: DK155674C; DE3049834C2; DK385779A; BE885205A; EP0035534A1; NL190850B; DK155674B; NL190850C; CH648047A5; DE3049834T1; NL8020343A

Abstract

Monocomponent polyurethane foam is prepared by adding to a pressure container which contains the pre-polymer of polyol and excess of polyisocyanate together with blowing and propelling agent shortly before use an activator which is an organic hydroxy compound with a molecular weight lower than 200 and at least two primary hydroxyl groups or a mixture of such hydroxy compounds which is liquid at 20 C. The activator can be added from a pressure container in which it is present under a gas pressure higher than the pressure in the container with the pre-polymer. A packing of activator consists of a pressure container in which the activator is present under a pressure of an inert gas of at least 5 atmospheres.

Description

A method for the manufacture of monocomponent polyurethane foam. Technical Field

The present invention concerns a method for the manufac¬ ture of a monocomponent polyurethane foam by discharge of a pre-polymer of a polyol and an excess of polyiso= cyanate from a pressure container in which the pre-poly= er is present together with a blowing and propelling agent.

Background Art

This method for the manufacture of polyurethane foam is very .advantageous compared to methods for the manu¬ facture of two-component polyurethane foam because it does not require a complicated equipment consisting of two containers, a mixing unit with associated spray gun and means for apportioning the components in a definite proportion but may be practised simply by operating a valve on the pressure container holding the pre-polymer. The pressure container may be a so-called aerosol can which is easily operated with one hand seeing that dis¬ charge of the foam is started and stopped at will, and the method is therefore especially suited for use in the building industry where the foam is used for insulation, glueing, as a mortar substitute, to secure door frames and window frames, and for the repair of cracks and crevices and to^' fill cavities.

However, a method of the said kind has the drawback that the pre-polymer in the pressure container must have such composition that curing of the discharged foam, which takes place by means of the moisture of the atmosphere, takes a long time. Moreover, foams hitherto made by this method have the drawback that they exhibit an e -?" pansion pressure after gelation of the foam with the result that it has been necessary to use stayings of e.g. door frames until the polyurethane foam is cured through .

Disclosure of Invention

The method according to the invention relieves the for¬ mer of these drawbacks and in preferred embodiments also the latter drawback because it is characterized in that shortly before use there is added to the pre-poly= mer in the pressure container an activator consisting of an organic hydroxy -compound having a molecular weight lower than 200 and at least two primary hydroxyl groups or a mixture of such hydroxy compounds which, is liquid at 20°C.

Hereby it is made possible to shorten the curing time of the polyurethane foam from the traditional 5-24 hours down to a few minutes or any other desired curing time within these two extremes, and this result can be ob¬ tained even with monocomponent polyurethane foam with¬ out amine catalyst in the activator portion so that by the method according to the invention one can avoid the danger of handling poisonous catalysts. Addition of an activator of the said kind is also advantageous compared to the addition of catalysts because the mix¬ ture of pre-polymer and activator will get a longer potlife, i.e. the period within which, the mixture re¬ tains such consistency that it can be sprayed, becomes longer.

The method according to the invention is. different, from the 2-component system in that the added amount of activator is small seeing that it may vary from zero to any desired small amount determined by th.e desired effect. The amount is usually under 15%, typically of the order of 5%, and it can therefore easily be intro¬ duced into the pressure container with, the pre-poly=

O P meric monocomponent polyurethane foam mixture. Use of a 2-component system requires exact apportioning of the two components within a margin of error of - 2%.

The activator may be for instance an aminoalcohol be- cause such compound has an especially strong influence on the curing time, but according to the invention the activator is preferably a glycol because by means of some glycols it can be obtained that the polyurethane foam becomes pressure-less, i.e. does not show any sub- stantial expansion after gelation so that putting up stayings before discharge of the foam can be dispensed with. Glycols which are particularly suited for this purpose are according to the invention ethylene glycol, dieth lene glycol, propylene glycol-1,3, butanediol-1,4, pentanediol-1,5, triethylene glycol, tetraethylene gly= col and glycerol. Ethylene glycol, propylene glycol- 1,3, butanediol-1,4, and glycerol are especially pre.- ferred.

It is surprising that it is possible to obtain a pres- sure-less foam by adding such glycols as activators to a. monocomponent polyurethane foam immediately before use seeing that the same effect is not obtained by letting the glycols form part of the polyol constituent initial¬ ly in the reaction with polyisocyanate.

The amount of activator to be used in the method accord¬ ing to the invention depends on the desired curing time but is in general much smaller than the amount of pre- polymer, typically 5-10%. The activator can therefore

*N be supplied in a small container which, accompanies the larger pressure container with the pre-polymer of mono- component polyurethane foam as an extra kit, and the user can add the activator if he desires to perform the method according to the invention and obtain the advantages thereby involved, or he can omit to add the

OMPI activator if he desires to use the monocomponent poly= urethane foam in the traditional manner without short¬ ened curing time.

Monocomponent polyurethane foam on pressure containers is normally supplied as so-called aerosol cans, i.e. pressure containers in which the pre-polymer is present together with the blowing and propelling agent which is a liquid having a steep temperature-pressure curve, e.g. a Freon, and which has a valve which is opened by merely'depressing the discharge tube. On account of the security regulations which apply to the use of the blowing and propelling agents used for monocomponent polyurethane foam the pressure in the aerosol cans does not exceed 5 atmospheres, and this fact therefore pro- vides possibility of adding the activator, when car¬ rying out the method according to the invention, in a particulary simple way which does, not call for any special equipment and does not make it necessary that together with the activator other chemical compounds become introduced which may have an effect on the blow¬ ing or the curing. According to the invention the ac¬ tivator is preferably added to the pre-polymer in the pressure container by transfer from another pressure container in which the activator is under a pressure of an inert gas higher than 5 atmospheres. The pres¬ sure container with the activator may be e.g. an aero¬ sol can with a valve similar to that of the aerosol can with, thepre-polymer so that- ransfer of the activ¬ ator can take place merely by pressing the discharge tubes of the two aerosol containers, against each other.

Accordingly, the invention further comprises a packing of activator for use in the method according to the in¬ vention which packing is characterized in that it is a pressure container in which an activator consisting of an organic hydroxy compound with a molecular weight low-

O er than 200 and at least two primary hydroxyl groups or a mixture of such hydroxy compounds which, is liquid at 2 200 CC iiss pprreesseenntt uunnddeer a pressure of an inert gas of at least 5 atmospheres.

According to the invention the pressure container is preferably filled to less than 50% with activator, and most suitable to less than 33%. Hereby it is ob¬ tained that activator can be transferred to the pressure container with the pre-polymer under almost constant pressure and without any substantial increase of the pressure in the pressure container with the pre-polymer.

Addition of the activator can also take place in other ways, e.g. the activator can be in an only partially filled small container without pressure and part of the pre-polymer be transferred from the pressure container to this small container. The heat of reaction will then increase the pressure in the small container so much that the contents of the small container then^'--may be transferred to the larger container in which, mixing of the total amounts of pre—polymer and activator then takes place immediately before the discharge of the foam.

If the method according to the invention is carried out with, the main purpose of obtaining a pressure-less foam a pre-polymer of polyol and polyisocyanate is used having such, excess of isocyanate that the equivalent ratio of isocyanate to hydroxyl is between 3:1 and 6:1 and an activator is added consisting of a glycol in an amount of 5-10% by weight of the pre-polymer.

The pressure container with the pre-polymer of polyol and polyisocyanate may contain the traditional addi¬ tives used for polyurethane foam such as plasticizers, surface active agents and dyestuffs which have no in-

\ OMPI ^" fluence on the reaction of thepre-polymerwith the ac¬ tivator but the object of which only is to control the physical properties of the formed foam or the viscosity of the mixture before curing.

Examples

The invention is illustrated by the following examples in which there is used as pre-polymer various reaction products of a polyol component and a diphenylmethane diisocyanate . The equivalent ratio of the two com- ponents is varied in some examples to illustrate the range within which a pressure- less foam can be obtained when using different activators . The freedom from pres¬ sure is ascertained by measuring the expansion in % of a point around a door frame which is not stayed.

Example 1. Comparison Example.

A monocomponent polyurethane foam on pressure container has the following composition

Qxypropylated glycerol (mol weight 1000) 100 ;^• parts by weight crude diphenylmethane diisocyanate (functionality 2.3) . 168 tris-2-chloroethylphosphate

(plasticizer) 32 - — - copolymer of siloxane and oxyal ylene

(surface active agent) . 2.5 - - - di-πethylaminoethanol 1.5 - - - mixture of Ereon 11 and Freon 12 150 - - -

The mixture is in a pressure container in a standard packing of 1 litre at a pressure of 5 atmospheres at room temperature . The equivalent ratio of isocyanate to hydroxyl is 4.04 : 1. After discharge the foam is touch dry in 20-30 minutes and cures in 5-24 hours , depending on the humidity of the air , in layers 5-10 cm thick . The foam is not pres¬ sure-less but shows an expansion of 24 % measured as in- dicated above.

Example 2

The same monocomponent polyurethane foam as in example 1 is used butbeforeuse an activator consisting of 25 g. of ethylene glycol is added.

The discharged foam is touch dry in 10-15 minutes and cures in 45 minutes and does not show any expansion during or after curing. After addition of the activa¬ tor it is possible still after about 12 minutes to dis¬ charge foam of the same quality.

Example 3. Comparison Example

A commercial 2-component polyurethane foam is: discharged i and measured under the same conditions as in examples 1 and 2 and shows an expansion of 18%.

Example 4

454 g. of a monocomponent polyurethane foam of the same composition as in example 1 is placed in a standard 530 ml pressure container. 30 g. of propanediol-1,3 is placed in a pressure container with a capacity of 100 ml,and the container is pressurized with nitrogen to a pressure of 12 atmospheres. The contents of the small container is transferred to the large container by con¬ necting the discharge tubes of the containers and press them against each other so that the valves are opened whereby the activator (propanediol-1,3) is forced into the large container by the nitrogen pressure. After

OMPI brief shaking the foam is discharged. It is touch dry in 8 minutes, cures in 50 minutes and shows no expan¬ sion.

Example 5

Example 4 is repeated but the 30 g. of propanediol-1,3 are replaced by 36 g. of butanediol-1,4 and instead of nitrogen compressed air is used. The discharged foam is touch, dry in 8 minutes and cures in 50 minutes and shows no expansion.

Example 6

A monocomponent polyurethane foam on pressure container has- the following composition :

Qxypropylated trimethylolpropane

( mol weight 1000) 100 parts by weight crude diphenyl-methane diisocyanate. 168 - - - tris-ohloropropylphosphate 32 - - - copolymer of siloxane and oxyalkylene 2.5 - - - di-methyldodecylamine 1.1 - - - mixture of Freon 11 and Freon 12 150 - - -

The mixture is in a pressure container in a standard packing of 1 litre at a pressure of 5 atmospheres at room temperature.

An activator consisting of 43.5 g. of diethylene glycol is in a small pressure container having a capacity of 200 ml under a carbon dioxide pressure of 10 atmos¬ pheres at room temperature .

The activator is transferred in the way described in example 4 to the pressure container with, the monocom¬ ponent polyurethane foam whereby the pressure in the larger container rises to 7 atmospheres. After brief shaking the foam is discharged. It is touch dry in 12 minutes and cures in 1 hour.

Example 7

Example 6 is repeated but using as activator 42 g. of pentanediol-1 , 5 . The formed foam is touch, dry after 7 minutes and cured through after 40 minutes. It shows an expansion of 3% .

Examples 8 , 9 , and 10

A monocomponent polyurethane foam mixture is prepared by mixing the following components :

Qxypropylated glycerol (mol weight 1000) 100 ^• parts crude diphenylmethane diisocyanate

(functionality 2.2) 180 - tris-chloropropylphosphate 50 ^■ - copolymer of siloxane and oxyal-kylene 3.0 - diπethylpiperazine 1.0 - mixture of Freons 150 -

The mixture is put on standard pressure containers with a capacity of 300 ml with 250 g . in each, and is acti¬ vated by introducing in the can immediately before use the following activators : 33 g . of triethylene glycol (example 8 ) , 42 g. of tetraethylene glycol (example 9 ) , and 13 .5 g. of glycerol (example 10) . The formed foams have the properties shown in table 1. Table 1

Example touch dry/min cured/min expansion

8 7 50 3

9 10 60 4

10 12 75 0

Ex amp le 11

A pressure container with monocomponent polyurethane foam mixture as in examples 8-10 is connected pressure- proof with, a small pressure container of 50 ml con- taining 14 g. of ethylene glycol which, is not under pressure, in such, manner that the small container is be¬ low and the large one on top. When the valves- of the containers are opened polyurethane foam mixture is for¬ ced into the small container until the latter is full and the pressure has been equalized. The two connected containers are briefly shaken and then placed with the small container on top. The mixture in the small -con¬ tainer will start to react whereby heat is generated so as to make the pressure rise, and the contents of the small container will be emptied into the larger con¬ tainer. After separation of the two containers the ac¬ tivated foam can be discharged from the large container. It is- touch- dry in 15 minutes, cures- in 1 hour, and shows no expansion.

Example 12

Examples: 8-10 are repeated but using as activator 14 g. of a mixture of equal parts- of glycerol and ethylene glycol. The. formed foam cures in 1 hour without expan¬ sion.

Example 13

OMPI Example 12 is repeated but using as activator 15 g. of a mixture in the ratio 1:2 of trimethylolpropane^'and ethylene glycol. The formed foam cures in 50 minutes without expansion.

Examples 14-20

From a basic polyol mixture of the following composi¬ tion:

Qxypropylated glycerol (mol weight 1000) 100 parts tris (chloropropyl) phosphate 50 copolymer of siloxane and oxyalkylene 3.0 - di-methylhexadecylamine 1.3 -

a series of pre-polymers are prepared with, varying ex¬ cess of diphenylmethane diisocyanate* as shown in table 2, and these pre-polymers are poured into standard pres- sure cans with, a capacity of 300 ml together with a constant amount of propellant which, is a mixture of Freon 11 and Freon 12.

Table 2

Exam- basic . isocya= : ^~. -.propel¬ NC0/α-I ^"ratio in pie No. polyol g.. nate z^~- lant g. pre-polymer.

14 85 80 85 3 :.4 : 1

15 80 85 85 3.8:1

16 75 90 85 4-3:1

17 70 95 85 4-9:1 18 65 100 85 5.6:1

19 60 105 85 6.3:1 ^"

20 55 110 85 7.2:1

Then foam is produced from these mixtures after addi¬ tion of an activator consisting of ethylene glycol from

OMPI 12

a pressure can with a capacity of 60 ml. The amounts of activator used and the properties of the foams are shown in table 3.

Table 3 -

5 Exam¬ Activa¬ Touch Expan¬ Remarks ple No . tor g . dry/min . sion

14 11.5 5 0 Foam a bit soft

15 12.5 7 0 Excellent foam

16 13 .5 11 0 Excellent foam

3 17 15 12 0 Excellent foam

18 16.5 21 0 Excellent foam

19 18 .0 23 0 Foam slightly brittle

20 19 .0 35 0 Foam very brittl

i ^' Example^' 21

The same monocomponent polyurethane foam as in example 1 is used but before use an activator is added consisting of 9 g. of diethanolamine and 18 g. of ethylene glycol. The discharged foam is touch dry in 5 minutes and cures in 20 minutes.

Example 22

Example 21 is repeated but the activator is replaced by 10 g. of triethanolamine and 20 g. of propanediol-1,3. The discharged foam is touch dry in 4 minutes and cures in 15 minutes. 13

Example 23

Example 2 is repeated but the dimethylolaminoethanol is omitted from the monocomponent polyurethane foam mixture and is instead added together with the 25 g. of ethylene glycol. Similar results as in example 2 are obtained.

OMPI

Claims

" Claims:

1. A method for the manufacture of a monocomponent polyurethane foam by discharge of a pre-polymer of a polyol and a polyisocyanate from a^'pressure container in which the pre-polymer is present together with a blowing and propelling agent, c h a r a c t e r i s e d in that shortly before use there is added to the pre-polymer in the pressure container an activator consisting of an organic hydroxy compound having a molecular weight lower than 200 and at least two primary hydroxyl groups or a mixture of such hydroxy compounds which is liquid at 20 C.

2. A method as claimed in claim 1, c h a r a c t e r - i s e d in that the activator is a glycol.

3. A method as claimed in claim 2, c h a r a c t e r - i s e d in that the glycol is ethylene glycol, diethylene glycol, propylene glycol-1,3, butanediol-1,4, pentanediol- 1,5, triethylene glycol, tetraethylene glycol or glycerol.

4. A method as claimed in claim 3, c h a r a c t e r ¬ i s e d in that the glycol is ethylene glycol, propylene glycol-1,3, butanediol-1,4 or glycerol.

5. A method as claimed in claims 1-4 for the manufacture of a pressure-less foam, c h a r a c t e r i s e d by the use of a pre-polymer having such excess of isocyanate that the equivalent ratio of isocyanate to hydroxyl is between 3:1 and 6:1, and by addition of a glycol in an amount of 5-10% by weight of the pre-polymer.

6. A method as claimed in claims 1-5, c h a r a c ¬ t e r i s e d in that the activator is added to the pressure container with the pre-polymer by transfer from a pressure container in which the activator is present under a pressure of an inert gas higher than the pressure in the container with the pre-polymer.

7. A packing of activator for use in the method accord¬ ing to claim 6, c h a r a c t e r i s e d in that it is a pressure container in which an activator consisting of an organic hydroxy compound with a molecular weight lower than 200 and at least two primary hydroxyl groups or a mixture of such hydroxy compounds which is liquid at 20 C is present under a pressure of an inert gas of at least 5 atmospheres.

8. A packing as claimed in claim 7, c h a r a c t e r ¬ i s e d in that the pressure container is filled to less than 50% with activator, preferably to less than 33%.