WO1997048756A1

WO1997048756A1 - Ecological foaming agent for polyurethane resins, particulary for the production of rigid foamed parts

Info

Publication number: WO1997048756A1
Application number: PCT/IT1997/000142
Authority: WO
Inventors: Luigi Granieri
Original assignee: Gn/Pi Di Luigi Granieri E Figli S.N.C.
Priority date: 1996-06-21
Filing date: 1997-06-19
Publication date: 1997-12-24
Also published as: PL324990A1; TR199800279T1; EP0861286A1; JP2000515177A; CA2227530A1; CN1196743A; AU3273097A

Abstract

The use of a water alcohol solution mixed with perchloroethylene as foaming agent for the production of foamed polyurethane is disclosed. Particularly described is the use of an alcoholic distillate mixed with perchloroethylene. The alcoholic content of the solution and the distillate is between 30 and 90 degrees. Also the amounts of such agent to be used in the mixture are indicated as parts by weight with respect to the current components.

Description

Ecological foaming agent for polvurethane resins, particularly for the production of rigid foamed parts

The present invention relates generally to the production of foamed resins or plastic foams as well as the problem of the replacement of products such as HCFC 141b or HCFC 142b which are used as foaming agents today even if they are harmful to the ozonosphere .

More particularly the invention relates to the investigation of new, wholly ecological foaming agents for polyurethane resins which have an ODP (Ozone Depletion Potential) equal to 0, are free of toxic effects, are fully compatible with the environment and capable of providing final products with mechanical characteristics comparable with those of the foamed parts provided by known foaming agents.

It is known that the quick reduction of the ozonosphere has caused the most developed countries to wholly give up using chlorofluorocarbide (CFC) and to replace them with the less harmful HCFC. However, following on international agreements, also such products have to be drastically reduced in a few years, warning sign of a full elimination. Therefore, the problem of finding an effective, not temporary substitute to such products is becoming topical . The use of alternative products, however, is not only requested by the need of protecting the environment. Actually, very binding safety rules for storing, transporting and manipulating HCFC have to be followed in the industry for the production of foamed polyurethane, with the result of an increase in the production cost as well as possible interruptions of the production cycle due to inspections of the sanitary board of control and the authority in charge for the study of industrial accidents. Therefore, the use of non-toxic products compatible with the environment is highly desirable.

The present invention seeks to provide a solution to such problems by finding a foaming agent for the production of polyurethane foams which is ecological, cheap, not dangerous and capable of providing final products with mechanical characteristics comparable with those of the current foaming agents without particular safety arrangements.

As known, polyurethane is a hardening resin characterized by the function: R-NH-CO-R' and produced by the reaction of an isocyanate with a polyol in the presence of a number of additives

(catalysts, surface-active agents, etc.) .

The poly-addition reaction can be carried out according to different methods providing products of different characteristics. If foaming agents are added to traditional components, foams having open- or closed-cell structures or a mixture thereof are produced. Such features determine the final characteristics of the material which is flexible, rigid or semirigid.

For the sake of a better clearness, specific reference is made in the present disclosure to the production of rigid foamed parts, particularly the construction of one-piece panels of sheet-metal and foamed polyurethane which are used in industrial building. It is self-evident that the foregoing is also valid for the use of foamed polyurethane in other industrial sectors . The use of one-piece panels is being spread for the installation ease and quickness as well as for the high performances. The high thermal insulation and the pleasant aesthetics make them of large use in industrial floors as well as in civil building for covers and walls. Said panels are formed of two metal supports of suitable shape which are provided by cold deformation of steel and/or aluminium bands into which foamed polyurethane is injected. In addition to metal bands to form said supports, the most important raw materials are the chemical compositions of the polyurethane, and namely: Isocyanate (M.D.I.) Polyol Activator (Dimethylcyclohexylamine) Foaming agent (HCFC 141b)

Such products are stored in air-conditioned plants and transferred to the site of use via underground pipes. The above panels are produced by a foaming method consisting of a filling and expansion process carried out on the site of final use. This is of course valid also for vessels, refrigerators, etc. The employed methods are two: a) a discontinuous method for the production of a little set of special, miscellaneous panels; b) an automatic, continuous method for homogeneous mass-production.

In the first case, the support metal sheets shaped and cut to measure are placed in pairs at a suitable distance from one another so as to form a die between the plates of a press, into which liquid polyurethane is injected by foaming machines. After curing the polyurethane fills the volume between the two support metal sheets. After some minutes of stabilization within the press, the formed panels are extracted and manually stacked in packs.

In the second case, the different processing steps (shaping of the supports, foaming of the polyurethane, stabilization of the polyurethane, cutting and stacking of the panels) are carried out at the same time. The bands of metal sheets are placed on two unwinding reels; the two metal sheets are fed to the two forming machines which give the desired form. Downstream, a homogeneous layer of polyurethane is deposited on the lower metal sheet by the foaming machine. After some seconds the produced foam expands and its expansion is held by the plates of the double- plate press. At the output of the press the polyurethane is stabilized and then the panel is shaped in its final form and size. A standard formulation of the mixtures currently used for providing the polyurethane foams used in the panels, expressed in parts by weight, is as follows: Isocyanate 143 Polyol 100 HCFC 141b 20

Activator 4

Such formulation may be changed according to the desired thickness and density of the panels. During experiments directed to find substitutes of HCFC 141b it was surprisingly found that the admixture of a solvent such as perchloroethylene (or tetrachloroethylene) with an alcoholic distillate of alcoholic content between 30 and 90 degrees produces a liquid substance which can be used as foaming agent giving the same results as HCFC 141b.

It is known that the term alcoholic distillates includes all of the alcoholic beverages prepared by distillation of an alcoholic liquid of lower concentration and fermentative nature. Such distillates can be classified according to the raw material of the fermentative process and the following treatments whereby the distillate is processed so as to be given flavour and taste . Thus, whisky, gin and vodka are originated from the fermentation of cereals, other kinds of gin and vodka from potatoes, brandy from fruit, rum from sugar cane, and the relative distillates are aged but nothing is added thereto. A number of tests were carried out with distillates obtained by condensation of vapours from the boiling of alcoholic solutions originated from the fermentation of sugar-liquids of different origin. Tests were carried out with distillates of wine, marcs, beets, plums, as well as distillates of fermented sugar-cereals, thereby achieving comparable results relative to the actual alcoholic content. It was then ascertained that a certain amount of water is necessary to facilitate the expansion: the alcoholic content should not be too high and in any case between 30 and 90 degrees.

By way of example the amounts of the two products which replace the foaming agent are indicated below as parts by weight related to the other components currently used in the production of foamed polyurethane according to a preferred formulation. Isocyanate 158

Polyol 100

Distillate (ale. cont . 60) 6.5

Perchloroethylene 4.5 Activator 4

Such amounts, however, were found susceptible of being changed within the following ranges, thereby providing final products which were different in density and rigidity: Isocyanate 130 to 180 parts by weight

Polyol 70 to 130

Distillate 3 to 12

Perchloroethylene 3 to 12 " Activator 3 to 7 " It is self-evident from the foregoing that the object of the present invention solves all of the problems relative to the environment, is not toxic, easily available on the market and cheap. To this regard it should be appreciated that the base product, i.e. the alcoholic distillate, can also be obtained from the recovery and the processing of city-waste. In a first phase, the inventor directed his investigation particularly to eau-de-vie which is originated as known from the distillation of marcs. Eau-de-vie of less refined quality is rich of methyl alcohol (however, not greater by law than 1% related to the total alcohol content) and upper alcohols. After filtration, clarification and dilution with water, a 60% alcohol volume eau-de-vie was used. During the experiments any alcohol, in addition to alcohol distillates, diluted in water and having alcoholic content between 40 and 100% was found utilizable as foaming agent in combination with perchloroethylene. Actually, any water alcoholic solution comprising aliphatic monovalent alcohols mixed in any proportion with water may be used with perchloroethylene. Such alcohols are mainly originated from chemical synthesis using hydrocarbons from petroleum and natural gases, greases and oils as well as from the fermentation of natural products.

It was found that the use of pure high-gradation alcohol diluted in water so as to lower the alcoholic content allows polyols to be used in the mixture for the production of foamed polyurethane without adding water, unlike the current methods. Actually, in addition to a natural water content of 0.15% by weight, a water amount of 2-2.5% by weight is added to industrial polyols for the production of rigid polyurethane foams . Such an amount which tends to evaporate during the process is necessary for forming the foam cavities.

By way of example the amounts of the two products which replace the foaming agent are indicated below as parts by weight related to the other components currently used in the production of foamed polyurethane according to a second preferred formulation of the present invention which has proved to be effective for a large range of polyols. Isocyanate 158 Polyol (without added water) 95

Water alcohol solution

(ale. cont. 60) 6.5

Perchloroethylene 4.5

Activator 4 Such amounts, however, were found susceptible of being changed, also according to the specific characteristics of the used polyols, within the following ranges, thereby providing final products which were different in density and rigidity: Isocyanate 80 to 180 parts by weight

Polyol (without added water) 70 to 130 "

Water alcohol solution 3 to 20 "

Perchloroethylene 2 to 12 " Various Activators 2 to 7 " A significant parameter is given by the boiling point of the foaming agent (alcoholic solution or perchloroethylene) which is between 40 and 93°C. It is self-evident from the foregoing that the object of the present invention solves all of the problems relative to the environment, is not toxic, easily available on the market and cheap. To this regard it should be appreciated that the base product, i.e. an alcoholic distillate or an alcohol, can also be obtained from the recovery and the processing of city- waste.

Some preferred embodiments of the invention are disclosed above. However, it should be understood that a number of changes and modifications can be made by those skilled in the art without departing from the scope of the present invention defined in the following claims.

Claims

1. Use of a water alcohol solution as foaming agent in the production of foamed polyurethane.

2. Use of a water alcohol solution in combination with perchloroethylene (or tetrachloroethylene) as foaming agent in the production of foamed polyurethane.

3. Use of a mixture of a water alcohol solution with alcoholic content between 30 and 90° and perchloroethylene as foaming agent in replacement of HCFC 141b in the production of foamed polyurethane.

4. A mixture for the production of foamed polyurethane characterized by the following components in the following proportions by weight:

Isocyanate 80 to 180

Polyol (without added water) 70 to 130

Alcohol 2 to 20 Water 1 to 3.5

Perchloroethylene 2 to 12

Various Activators 2 to 7

5. The mixture for the production of foamed polyurethane of the preceding claim characterized in that the alcohol has an alcoholic content between 60 and 100 degrees.

6. A foaming agent for foamed polyurethane, wherein it consists of a mixture of a 60° water alcohol solution and perchloroethylene in the amount of 6.5 and 4.5 parts by weight, respectively.

7. The foaming agent for foamed polyurethane of the preceding claim, characterized in that the alcohol is produced by chemical synthesis.

8. Use of an alcoholic distillate as foaming agent in the production of foamed polyurethane.

9. Use of an alcoholic distillate in combination with perchloroethylene (or tetrachloroethylene) as foaming agent in the production of foamed polyurethane.

10. Use of a mixture of an alcoholic distillate with alcoholic content between 30 and 90° and perchloroethylene as foaming agent in replacement of HCFC 141b in the production of foamed polyurethane.

11. A mixture for the production of foamed polyurethane characterized by the following components in the following proportions by weight: Isocyanate 130 to 180

Polyol 70 to 130

Alcoholic distillate 3 to 12

Perchloroethylene 3 to 12

Activator 3 to 7

12 The mixture for the production of foamed polyurethane of the preceding claim characterized in that the alcoholic distillate has an alcoholic content between 30 and 90 degrees.

13. A mixture for the production of foamed polyurethane characterized by the following components in the following proportions by weight:

Isocyanate 158 Polyol 100

Distillate

(ale. cont. 60) 6.5

Perchloroethylene 4.5

Activator 4

14. A foaming agent for foamed polyurethane, wherein it consists of a mixture of a 60° alcoholic distillate and perchloroethylene in the amount of 6.5 and 4.5 parts by weight, respectively.

15. The foaming agent for foamed polyurethane of the preceding claim, characterized in that the distillate is produced by condensation of vapours from the boiling of alcoholic solutions deriving from the fermentation of sugar liquids of any nature.