KR820001053B1 - Process for preparing rigid polyurethane foams using latent catalysts - Google Patents

Abstract

Diorganotin S compds. are latent catalysts for prepn. of polyurethane foams, allowing sufficient cream and rise times for the compn. to completely fill the mold. The ter-amine (I; R3, R4, R5 = C1-20 alkyl, C2-4 hydroxyalkyl, cycloalkyl, aryl, aralkyl) are also used in catalyst. Thus, 32.8 parts of a mixt. of sorbitol-based polyol 100, surfactant 1.5, and blowing agent 30 parts was combined with polymethylenepolyphenylene polyisocyanate 30.5, diethanolamine 0.15, and dibutyltin sulfide 0.1 part to give cream time 78 sec and rise time 156 sec compared with 35 sec and 113 sec, resp., for a compn. contg. dibutyltin bis (lauryl mercaptide).

Description

Process for producing rigid polyurethane foam

The present invention relates to a process for the production of rigid polyurethane foams, and more particularly to the production of rigid polyurethane foams in which certain diorganotin compounds are used in combination with tertiary amines as gel catalysts in order to delay the initiation of the polymerization reaction. This delay can be beneficial for many applications.

Rigid rigid polyurethane foams can be prepared using a variety of well known methods. In some cases, it may be desirable to manufacture this foam where it will be used. The rigid polyurethane foam can be used on the outer surface of the storage tank or between the roof of the building or the inner and outer walls of the building to achieve an insulation effect, and the polyurethane foam can be sprayed for this purpose. Polyurethane foam, which is directly sprayed on site, is very economically advantageous because it is easy to spray.

For this use, it is most preferable to use two components, one is polyfunctional isocyanate such as polyurethane polyphenylisocyanate and the second component is to mix polyol, gelling catalyst and blowing agent with denaturing agent or additive. Surfactants, such as siloxane polymers, are also typically included to give a uniform bubble structure to the final product. The second component is used as a premix prepared weeks or months before reacting with isocyanates.

Organotin compounds are representative of high activity catalysts for the reaction of isocyanates with polyols. This reaction usually proceeds very quickly, so that the liquid composition used to make the foam has a viscosity such that it does not enter all parts of the mold or other container into which it is injected. If incomplete filling of the mold occurs, the foam product will fail because the shape of the final foam does not match the shape of the mold or other container used to form it. The value of rigid polyurethane foams as insulation is significantly reduced if the space of the inner and outer walls of the container or building used to maintain the temperature of the stored solid or liquid while suppressing heat transfer is not completely filled.

An object of the present invention is to delay the cream time of a rigid polyurethane foam prepared by using a mixture of a tetravalent organotin compound and a tertiary amine as a gelling catalyst. Surprisingly, it can be seen that this object can be achieved by using sulfur-containing diorganotin compounds as one component of the gelling catalyst.

Therefore, the present invention relates to a polyol having at least two active hydrogen atoms measured by the Jerevynov method in the production of rigid polyurethane foams by reacting polyols with isocyanates in the presence of blowing agents, surfactants and gelling catalysts. As a catalyst, a diorganotin compound represented by the formula: R ¹ R ² SnSx, R ¹ R ² n (SCN) ₂ , (R ¹ R ² SnSCN) ₂ Sx and (R ¹ R ² SnSCN) ₂ O and a formula: R By using a latent catalyst composed of tertiary amine of ³ R ⁴ R ⁵ N or heterocyclic tertiary amine, it is possible to extend the cream time when preparing the rigid polyurethane foam. Provide the recipe.

Wherein R ¹ and R ² each represent an alkyl group having 1-20 carbon atoms, cycloalkyl, aryl, alalkyl and an alkali group, and R ³ , R ⁴ and R ⁵ each having 1-20 carbon atoms Alkyl group, hydroxy alkyl group having 2-4 carbon atoms, cycloalkyl, aryl, alalkyl and alkaryl group, x is an integer of 1-4)

Diorganotin compounds which are one of the catalysts used in the present invention are diorganotin sulfides, diorganotin dithiocyanates, bis (thiocyanato diorganotin) sulfides or bi (thiocyanatodiorganotin) oxides.

In the diorgano tin compound, two hydrocarbon groups represented by R ¹ and R ² are alkyl groups having 1-20 carbon atoms, cycloalkyl, aryl (particularly phenyl), alalkyl or alkaryl, and the alkyl group in the alalkyl and alkaryl group is 1 -12 carbon atoms, and an aryl group is preferably phenyl. The most suitable organotin compounds are those wherein R ¹ and R ² are both methyl, butyl, octyl or phenyl, and such compounds are good for use in the present invention. Wherein R ¹ and R ² may be the same or different. The optimal concentration of the diorgano tin compound is determined by various factors such as the reactivity of the polyol and isocyanate and the desired cream time or increase time, but preferably 0.1-10 parts by weight, and most preferably 0.1-5.0 parts by weight of 100 polyols. to be. Diol organotin compounds are used in combination with tertiary amines used as gelling catalysts in hard urethane foams. Suitable amines are dimethyl ethanol amine, N-ethyl morpholine and triethylene diamine. The concentration of the tertiary amine is preferably 0.1 to 4 parts by weight per 100 parts of polyol.

As mentioned above, the tertiary amine component has three monovalent hydrocarbon groups R ³ , R ⁴ and R ⁵ bonded to a nitrogen atom. Also, two carbon atoms bonded to a nitrogen atom generally form a divalent hydrocarbon group representing a 5-6 membered heterocyclic ring. This heterocycle may contain other heteroatoms such as oxygen, nitrogen and sulfur. The ring may also have one or more double bonds, for example pyridine. N-ethylmorpholine, a kind of heterocyclic tertiary amine, is a 6-membered ring of 4 carbon atoms, 1 oxygen atom and nitrogen atom, in which case there is no unsaturated bond in the ring. Tertiary amines that are also commonly used as catalysts for the production of rigid polyurethane foams include triethylamine, diethylethanolamine, bis (dimethylaminoethyl) ether, tetramethylbutane, diaminetetramethylethyleneamine, dimethylpiperazine, trimethylaminoethylpipe Razine, N-methyldicyclohexylamine, N-cyclohexylmorpholine, N- (2-hydroxyethyl) cyclohexylamine, N- (2-cyanoethyl) cyclohexylamine, N- (3-aminopropyl ) Cyclohexylamine and N-phenylcyclohexylamine.

In addition to the polyol diorganotin compounds and tertiary amines of the present invention, precursor compositions typically exhibit gaseous products that form bubbles within the polyol-isocyanate mixtures that react or boil or decompose at elevated temperatures resulting from polyol and isocyanate reactions. Blowing agent and surfactant. Preferred blowing agents are chlorine-containing fluorocarbons having a boiling point of about 35-90 °. The surfactant is preferably a siloxane-alkylene oxide copolymer, which is present in an amount of about 1-5 parts by weight per 100 parts of polyol.

The latent gelling catalyst of the present invention is suitable for use with virtually all known polyurethane alkylene polyols or polyfunctional isocyanates commonly used in making rigid polyurethane foams. Suitable polyalkylene polyols are generally liquid compounds with an average molecular weight of 500-5000, for example hydroxyl-containing polyethers, polyesters, polyamides, alkylglycols, polycapcaptans and polyamines. This polyalkylene polyol has a primary or secondary active hydroxyl group. Examples of hydroxyl-containing polyethers or polyesters are fatty acid glycerides having hydroxyl values of 50-75, such as castor oil, hydrogenated castor oil and natural oils. The hydroxyl terminal group-containing polyethers, which are a preferred type of polyalkylene polyols, include polyalkylene glycols such as polyethylene glycol and polypropylene glycol. The molecular weight of these compounds is preferably 200-500.

Particularly preferred polyethers are obtained by polymerizing propylene oxide in the presence of sucrose or other compound having at least three hydroxyl groups. The obtained product exhibits the multifunctionality necessary to obtain the crosslinking properties of the rigid polyurethane foam. Hydroxyl end group-containing polyesters, the second type of polyalkylene polyols, are esterified condensations of aliphatic dibasic carboxylic acids with glycols, triols or compounds thereof in proportions where most or all of the polymer chains contain hydroxyl groups. Can be prepared by reaction. Dibasic carboxylic acids suitable for polyester production include aliphatic and aromatic acids such as adipic acid, fumaric acid, sebacic acid and phthalic acid isomers. Diacid reacts ethylene glycol, recalled diethylene glycol or trimethyl with polyhydroxylated compounds such as propane. Multifunctional isocyanates used in the manufacture of rigid polyurethane foams include both polyisocyanates and polyisothionates.

Although the invention specifically describes only the reaction of any kind of polyfunctional isocyanate, it is generally applicable to the reaction of any compound containing two or more -N = C = G groups, where G is oxygen or sulfur. have. Compounds having such conditions include polyisocyanates and polyisothiocyanates having the formula R (NCG) _x , where the average value of x is greater than 2, preferably 2.1-3.0, and R is alkylene, substituted Alkylene, arylene, substituted arylene or other polyvalent hydrocarbon groups containing one or more aryl-NCG bonds and one or more alkyl-NCG bonds.

Suitable isocyanates include polyfunctional by-products obtained in the preparation of polyylene diisocyanate isomers, and polymethylene polyphenyl isocyanate is an example of such by-products. For example, triisocyanate obtained by reacting 1 mol of triol and 3 mol of arylene diisocyanate is also suitable as a reaction product obtained by 3 mol of polyylene diisocyanate and 1 mol of hexane triol. Oligomeric and polymeric isocyanates of the general formula (RNCG) _x and [R (NCG) _x ] _y (where x and y are 2.1-10) are also of the general formula M (NCG) _x where x is a number greater than 2 Is a difunctional or polyfunctional atom or group).

과 요소결합

이 형성된다. 형성된 우레탄폼의 원하는 밀도와 가교결합도에 따라 이소시아네이트대 활성수소의 당량비는 0.8-1.2이고, 바람직하기는 0.9-1.1일 때이다. 이소시아네이트이외의 모든 성분을 함유하는 프리커서는 경질유레탄폼을 사용할 장소에서 제조하는 경우에 바람직하다. 이것은 해당 프리커서의 각 성분을 개량하여 균일하게 혼합하는 시설이 없는 현장에서 행한다. 이때 프리커서조성물과 다관능가 이소시아네이트의 예비계량양을 표의 제조직전에 혼합한다. 얻은 혼합물을 각 용도에 따라 물체의 표면에 분사시키거나 용기에 주입시켜 반응시켜서 경질 폼을 생성시킨다.The amount of isocyanate is usually used in excess of the stoichiometric amount required for the reaction with the active water generated by the polyol and the water present, and the urethane bond in the polymer chain.

And element bonding

Is formed. The equivalent ratio of isocyanate to active hydrogen is 0.8-1.2, preferably 0.9-1.1, depending on the desired density and degree of crosslinking of the urethane foam formed. Precursors containing all components other than isocyanate are preferable when produced at the place where the hard urethane foam is to be used. This is done at the site where there is no facility to improve and uniformly mix each component of the precursor. At this time, the preliminary amounts of the precursor composition and the polyfunctional isocyanate are mixed immediately before the preparation of the table. The resulting mixture is sprayed onto the surface of the object or injected into a container for reaction to produce a rigid foam.

The following example compares its activity which clarifies the latentness peculiar to the gelling catalyst used of the present invention with that of a known organotin catalyst using the same amine catalyst. Examples include representative sulfur-containing diol organotin compounds, and do not limit the scope of the invention. The parts or percentages used herein in the examples are by weight.

The time from the mixing of the polyfunctional isocyanate and other components used in the preparation of the foam to the initiation of the polymerization reaction is called the cream time. Initiation of the polymerization involves an increase in the viscosity of the reaction mixture and a change from the first clear reaction mixture to an opaque mixture. The time from the mixing of all the reagents to the rounding of the foaming reaction is called the increase time.

Example 1

A precursor or masterbatch for producing rigid polyurethane foams was prepared by mixing polyols, surfactants and blowing agents in the following proportions. This polyol is a copolymer of polyhydroxy containing propylene oxide and ethylene oxide with a hydroxy value of 490, which is commercially available as LS-490 from Union Carbide Chemicals. The surfactant is a siloxane-oxyethylene-oxypropylene copolymer sold by Union Carbide Chemical Company LS-5340.

32.8 parts of this precursor were mixed with 30.5 parts of polymethylene polyphenyl isocyanate having an isocyanate equivalent of 133 parts, 0.3 part of mole, 0.15 part of dimethylethanolamine, and about 0.1 part of organotin compound. The resulting mixture was stirred for a few seconds and poured into a suitable vessel to foam. The cream tin and rise times of the evaluated organic tin compounds and the respective compositions are shown in the following table.

The data obtained in the table above demonstrate that the diorganotin catalyst of the present invention is specific in the latentness of activity on rigid polyurethane foams.

Three control compounds actually exhibit shorter cream times. It can be seen that the tin and sulfur bonds of these control compounds are the most reactive as the time required for initiation of the polymerization is shorter.

Example 2

This example mixes 32.8 parts of the catalyst according to the invention, 32.8 parts of the precursor as in Example 1 with 30.5 parts of polymethylene polyphenyl isocyanate and uses a Martin-swapp foamer, using a commercial scale rigid polyurethane foam production apparatus. Was processed in a container.

This device is a representative device used to make foams for large buildings such as insulated buildings or tanks to maintain a constant temperature. The cream time and rise time indicated by the composition containing two diorganotin catalysts and two known catalysts used in the present invention are shown in the following table.

The data demonstrate that the cream time was increased by 20-60% when using the diorganotin compound of the present invention compared to the use of the known organotin catalyst. It takes more time to uniformly inject this composition into a mold or other container, or to remove or spray the foam, before the flow can be disrupted by rapid rise in viscosity due to the polymerization reaction. Since the time required to fill the mold is increased relatively little, a complete failure of filling the foam with the blowing agent avoids the loss of time and energy and material that would otherwise be required to evacuate the product.

It should be noted that the cream time obtained when the diorganotin compound according to the present invention is used in combination with a tertiary amine is significantly longer than the conventional catalyst, and in most cases, the rise time is also constant. This means that it is very beneficial for continuous blowing agent manufacturing operations. Important for such an operation can minimize the time for mixing the reagents to remove the blowing agent from the mold or conveyor forming the blowing agent.

Claims (1)

In preparing a rigid polyurethane foam by reacting a polyol having at least two active hydrogen atoms and a polyfunctional isocyanate measured by the Zerevinov method in the presence of a blowing agent, a surfactant, and a gelling catalyst, the formula R as the gelling catalyst ¹ R ² S _n S | _x , R ¹ R ² S _n (SCN) ₂ , (R ¹ R ² S _n SON) | _{By using a} diorganotin compound represented by ₂ S _x or (R ¹ R ² S _n SCN) ₂ O and a catalyst of a tertiary amine or a heterocyclic tertiary amine of R ³ R ⁴ R ⁵ N, A method for producing a rigid polyurethane foam, characterized in that the time until the reaction of both by mixing the polyol and isocyanate is prolonged. Wherein R ¹ and R ² each represent an alkyl group having 1 to 20 carbon atoms, a cycloalkyl, an aryl, an alalkyl and an alkali group, and R ³ , R ⁴ and R ⁵ each represent an alkyl group having 1 to 20 carbon atoms , Hydroxy alkyl group having 2-4 carbons, cycloalkyl, aryl, alalkyl and alkaryl group, x is 1-4 integer)