KR0159915B1 - Process for the preparation of rigid polyurethane foam - Google Patents

Abstract

FIELD OF THE INVENTION The present invention relates to a process for producing rigid polyurethane foams from polyols and polyisocyanates, the process comprising the use of an aqueous polymer emulsion comprising a polymer of ethylenically unsaturated monomers, thereby providing chlorofluoro The amount of carbon may be reduced or the species may be excluded.

Description

Process for producing rigid polyurethane foam

The present invention relates to a process for producing rigid polyurethane foams, and more particularly to a method for improving the physical properties of rigid polyurethane foams.

Rigid polyurethane foams have been prepared by reaction between polyfunctional isocyanates and polyols (eg, polyester polyols, polyether polyols, etc.) using foaming agents in the presence of amine catalysts, metal catalysts and the like. Useful rigid foams typically have good thermal and lightweight structural properties. Therefore, rigid foams can be widely used as materials for thermal insulation materials, building materials, structural materials and the like.

Conventionally, when producing rigid polyurethane foams, chlorofluorocarbons such as CFC-11 or CFC-12 and water have been used as blowing agents. Recently, due to environmental destruction problems, the use of chlorofluorocarbons has been limited. The blowing agent comprises only water, or when combining chlorofluorocarbons and water, it is preferred to include a large amount of water and a very small amount of chlorofluorocarbons.

However, when only water is used as the blowing agent, or when a large amount of water is used, instead of the reaction between the isocyanate and the polyol required, water preferentially reacts with the isocyanate to form high crystalline urea bonds. This results in degradation of properties such as dimensional stability, crushability, thermal insulation properties and adhesive properties. Japanese Patent Nos. 90 / 281,021, 91 / 287,639 and 92 / 239,516 describe methods using polymer polyols prepared by polymerizing ethylenically unsaturated monomers in polyols to overcome these problems. However, the method does not satisfactorily suppress deterioration of physical properties.

The present invention relates to a process for producing rigid polyurethane foams by reacting polyols and polyisocyanates in the presence of catalysts, blowing agents and, optionally, surfactants. Rigid polyurethane foams with good physical properties can be prepared by using, as blowing agents, water comprising polymers of ethylenically unsaturated monomers in emulsified or dispersed form. Advantageously, deterioration of the physical properties that occur when using water as blowing agent can be avoided.

Accordingly, the present invention relates to a method for alleviating the deterioration of physical properties that occur when water is used as a blowing agent in the manufacture of rigid polyurethane foams.

The present invention relates to a process for improving the properties of rigid polyurethane foams by using an aqueous polymer emulsion comprising a polymer of ethylenically unsaturated monomers as blowing agent in the manufacture of rigid foams.

The process according to the invention is a conventional rigid polyurethane foam except that the preparation of conventional rigid polyurethane foam using water as blowing agent is carried out using an aqueous polymer emulsion comprising a polymer of ethylenically unsaturated monomers instead of water. It can be easily carried out by the manufacturing method of.

Suitable aqueous polymer emulsions for use in the present invention can be readily prepared by well known emulsion polymerization techniques by polymerizing the emulsified ethylenically unsaturated monomers dispersed in water with an emulsifier such as a surfactant or protective colloid. Can be. For example, emulsion polymerization may be achieved by dispersing one or more emulsifiable monomers in water at a concentration of 20 to 70% by weight in the presence of 0.1 to 10 parts by weight of an emulsifier per 100 parts by weight of monomer, and then 1 to 2 per 100 parts by weight of monomer. It can be easily carried out by addition in parts by weight.

The polymerization can typically be carried out at a temperature of 40 to 90 ° C., and the time required for the polymerization is usually in the range of 2 to 10 hours. The reaction may also be carried out under pressure when using monomers having a high vapor pressure. If desired, the reaction can be carried out using pH adjusters, polymerization modifiers and other well known additives. Alternatively, an aqueous polymer emulsion comprising polymers of ethylenically unsaturated monomers used in the present invention is prepared by polymerizing ethylenically unsaturated monomers in an organic solvent and then dispersing and emulsifying the resulting polymer in water with a surfactant. can do.

There is no particular limitation on the type of ethylenically unsaturated monomer used, and any monomer can be used as long as it can form an aqueous polymer emulsion containing a polymer. Thus, deterioration of the physical properties of rigid polyurethane foams made using water as blowing agent can be improved by selecting the appropriate monomers.

Examples of preferred ethylenically unsaturated monomers include ethylene, butadiene, isoprene, 1,4-pentadiene, 1,6-hexadiene, 1,7-octadiene, styrene, α-methylstyrene, 2,4-dimethylstyrene, ethyl Hydrocarbon monomers such as styrene, isopropyl styrene, butyl styrene, phenyl styrene, cyclohexyl styrene and benzyl styrene; Substituted styrenes such as chlorostyrene, 2,5-dichlorostyrene, bromostyrene, fluorostyrene, trifluorostyrene, iodostyrene, cyanostyrene, nitrostyrene and N, N-dimethylaminostyrene; Methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isopropyl (meth) acrylate, octyl (methyl ) Acrylate, phenyl (meth) acrylate, dimethylaminoethyl methacrylate, glycidyl acrylate, (methyl) acrylonitrile, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) Acrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl (meth) acrylate, mono- or di- (meth) acrylate of propylene glycol, mono of polypropylene glycol Or alkylene articles prepared from di- (meth) acrylates, mono- or di- (meth) acrylates of polybutylene glycol, two or more alkylene oxides containing from 2 to 4 carbon atoms Mono- or di- (meth) acrylates of the recall, (meth) acrylic monomers such as (meth) acrylic acid, ie acrylic and methacryl monomers; Vinyl acetate, vinyl chloroacetate, vinyl butyrate, isopropanol acetate, vinyl formate, vinyl methacrylate, vinyl methoxyacetate, vinyl benzoate, vinyl naphthalene, vinylidene bromide, vinyl methyl ether, vinyl ethyl ether, vinyl propylene ether Vinyl ethers or vinyl esters such as vinyl butyl ether, vinyl 2-ethylhexyl ether, vinyl phenyl ether, vinyl 2-methoxyethyl ether, vinyl ethyl ketone or vinyl phenyl ketone; And organic acids having double bonds and derivatives thereof such as dimethyl maleate, dimethyl fumarate, monomethyl itaconate, maleic acid, itaconic acid or fumaric acid. Styrene, methyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate or methacrylate, mono-acrylate or -methacrylate of polyethylene glycol, acrylic acid, methacrylic acid, and the like. Particularly preferred. These monomers may be used alone or in combination with two or more monomers.

Aqueous polymer emulsions having 20 to 70% by weight, preferably 30 to 50% by weight, of solids are 0.5 to 20 parts (pphp), preferably 1 to 15 pphp, most preferably 1 to 10 pphp per 100 parts of polyol. In amounts it is used as blowing agent in rigid polyurethane foam formulations. When the polymer emulsion is used below the lower limit, the physical properties of the rigid polyurethane foam to be produced are not improved, and when used above the upper limit, it is not sufficiently mixed with the polyol.

Suitable polyisocyanates for use in preparing rigid polyurethane foams using the aqueous polymer emulsions according to the invention are those typically used in the manufacture of rigid polyurethane foams. Examples of suitable isocyanates include tolylene 2,4-diisocyanate, tolylene 2,6-diisocyanate, diphenylmethane 4,4'-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate and the like. . Preferably, the polyisocyanate is used at an isocyanate index in the range of 80 to 300.

There is no particular limitation on the kind of polyol used in the present invention, and conventionally well-known polyether polyols and polyester polyols may be used. Suitable polyols include, for example, polyether polyols which can be prepared by addition reactions of polyhydric alcohols such as glycols, glycerin, pentaerythritol, trimethylol propane, sucrose and the like with ethylene oxide or propylene oxide; Amine polyols which may be prepared by addition reaction of amines such as ethylenediamine, diethylenetriamine, tolylenediamine, diphenylmethanediamine, triethanolamine and the like with ethylene oxide or propylene oxide; Polyester polyols, preferably polyether polyols, which may be prepared from polybasic organic acids and polyhydric alcohols; There are polymeric polyols that can be prepared by polymerizing ethylenically unsaturated monomers in polyether polyols and / or polyester polyols.

In preparing the rigid polyurethane foam according to the present invention, any catalyst conventionally used to prepare a urethane polymer can be used. Typical examples of useful catalysts include triethylenediamine, dimethylcyclohexylamine, tetramethylhexanediamine, bis (dimethylaminoethyl) ether, tri (dimethylaminopropyl) hexahydrotriamine, 1-isobutyl-2-methylimidazole And 1,2-dimethylimidazole, dimethylaminoethanol, diethylaminoethanol, pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, methylmorpholine, ethylmorpholine, quaternary ammonium salts, salts of organic acids Such as amine catalysts, and tin catalysts such as stanus acetate, dibutyltin dilaurate.

In preparing rigid polyurethane foams, surfactants such as organopolysiloxanes, ignition retarders such as halogenated organophosphorus compounds, and other commonly used additives can be used. The process according to the invention can be easily carried out by using hydrochlorofluorocarbons such as HCFC-141b, HCFC-22 or HCFC-123 as blowing agents.

In the examples below, parts are parts by weight.

Production Example A

650 g deionized water, 10 g of surfactant (Newool 271A, product of Nippon Nyukazai Co., Ltd.) and monomer mixture (33.3 parts of styrene, n- After charging 15 g) consisting of 66.7 parts of butyl acrylate and 2 parts of acrylic acid, the mixture was left at 80 ° C. under a stream of nitrogen. A solution of 1 g of ammonium persulfate in 50 g of deionized water was added and then reacted at 80 ± 1 ° C. for 30 minutes. 285 g of a monomer mixture consisting of the same components as described above were added to the reaction mixture at 80 ± 1 ° C. for 1 hour and then reacted at 80 ± 1 ° C. for 4 hours. After the reaction was completed, the pH of the reaction mixture was adjusted to 7.5 with aqueous ammonia to yield a milky white liquid aqueous polymer emulsion having a viscosity of 70 cps at 20 ° C. The liquid included 30 wt% solids and 70 wt% water.

Production Examples B to H

The procedure of Preparation A was repeated, but the milky white liquid aqueous polymer emulsions (B) to (H) having the viscosity shown in Table 1 were calculated using the monomer mixtures listed in Table 1.

Example 1

Rigid polyurethane foams having the physical properties shown in Table 3 were prepared using the rigid foam formulations listed in Table 2 and the aqueous polymer emulsion (A) prepared in Preparation Example A. The results show that the dimensional stability of the foams obtained in this way was significantly higher than any of the foams of the comparative examples. Rigid polyurethane foams were prepared as follows and their physical properties were also measured.

The mixture comprising the polyol, silicone surfactant, amine catalyst and aqueous polymer emulsion was mixed with stirring to yield 112 g of the mixture. After adding 209.2 g of isocyanate maintained at the same temperature to the mixture maintained at 20 ± 1 ° C., the resulting mixture was stirred at about 5,000 rpm for 5 seconds, which was then connected to a wooden box (20 cm × 20 cm) connected with a polyethylene sheet. ) Quickly poured to form a urethane foam (the top of the wood box was opened).

The cream time, gel time, rise time, and tacky scavenging time were measured as follows. The term cream time means the time that elapses from mixing the MDI CR-200 and other chemicals until the foam mixture begins to swell; Gel time means the time required to improve the viscosity of the foam compound; The rise time means the time required for the height of the foam to maximize; Sticky erasure time means the time that elapses until the foam becomes non-tacky. According to JIS K S401, the foam density of the polyurethane foam prepared above was measured. Polyurethane foam was cut to make a core foam of size 8 × 8 × 2.5 cm to measure the dimensional stability rate, which was left for 48 hours at a temperature of 23 ± 1 ℃ and a humidity of 50 ± 5% and then of The change was measured.

[Examples 2 to 9]

The procedure of Example 1 was repeated but the amount of isocyanate and aqueous polymer emulsion shown in Table 3 was used. A foam with improved dimensional stability was obtained. The results are also summarized in Table 3.

EXAMPLES 10 AND 11

The procedure of Example 1 was repeated, using aqueous polymer emulsions (D) and (G), and the rigid foam formulations shown in Table 4, respectively. The physical properties of the rigid foams are summarized in Table 5. The results show that the dimensional stability of the foams prepared according to the invention is significantly higher than the foams of the comparative examples.

The types of aqueous polymer emulsions used are listed in Table 6.

Polyol: Amine polyether (a mixture of 30 parts by weight of AE-302 (manufactured by Chiba Polyol Co., Ltd.) and 70 parts by weight of SU-450L (manufactured by Mitsui Toatsu Chemicals, Inc.)]

Silicone Surfactant: B-8404 from Goldschmidt Co., Ltd.

Amine Catalyst: Tetramethylhexanediamine

Amine catalyst: 13 parts by weight of aminoalcohol 2Mabs (manufactured by Nippon Nyukazai Co., Ltd.) and 22 parts by weight of DABCO DC-2 (manufactured by Air Products and Chemicals, Inc.) and DABCO TMR (manufactured by Air Products and Chemicals, Inc.) 65 parts by weight of the mixture)

HCFC-141b: dichloromonofluoromethane

Comparative Example 1

Rigid polyurethane foams were prepared according to Example 1 using 5.6 parts of water instead of 8.0 parts of an aqueous polymer emulsion (A) yielding a polyurethane foam having the physical properties shown in Table 3.

Comparative Example 2

Rigid polyurethane foams were prepared according to Example 4, using 6 parts of water instead of 10 parts of the aqueous polymer emulsion (D) yielding a polyurethane foam having the physical properties shown in Table 3.

Comparative Example 3

Rigid polyurethane foams were prepared according to Example 10, using 1 part water instead of 1.7 parts of an aqueous polymer emulsion (D) yielding a polyurethane foam having the physical properties shown in Table 5.

Thus, in preparing rigid polyurethane foams according to the invention, aqueous polymer emulsions comprising polymers of ethylenically unsaturated monomers emulsified in water can be used in place of water as blowing agents and the resulting polyurethane foam It has good physical properties compared to any of the foams made using water as blowing agent.

In addition, the method of the present invention can be carried out by using no chlorofluorocarbons or reducing the amount thereof, which is thought to destroy the ozone layer. Thus, rigid polyurethane foams can be produced by processes that do not adversely affect the environment.

Claims (20)

A process for preparing rigid polyurethane foams by reacting an organic polyisocyanate with a polyol in the presence of a blowing agent and, optionally, a surfactant, comprising using an aqueous polymer emulsion comprising a polymer of ethylenically unsaturated monomer as a blowing agent. How to. The method of claim 1 wherein the emulsion comprises 20 to 70 weight percent of the polymer and is used at 0.5 to 20 parts of polymer per 100 parts of polyol. The process of claim 2 wherein said emulsion is used in 1-15 parts of polymer per 100 parts of polyol. The method of claim 3, wherein the emulsion comprises 30 to 50 weight percent of the polymer. 3. The polymer of claim 2 wherein the polymer is styrene, methyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate or methacrylate, mono-acrylate or -methacryl of polyethylene glycol A method comprising an ethylenically unsaturated monomer selected from the group consisting of latex, acrylic acid, methacrylic acid, and mixtures thereof. The method of claim 4, wherein the polymer is selected from the group consisting of styrene, acrylic acid, butyl acrylate, 2-hydroxy ethyl methacrylate, polyethylene glycol monomethacrylate, 2-ethylhexyl acrylate, and mixtures thereof. A method comprising an ethylenically unsaturated monomer. 6. The process of claim 5 wherein said aqueous polymer emulsion is used in 1-15 parts of polymer per 100 parts of polyol. 8. The process of claim 7, wherein the emulsion is used in 1 to 10 parts of polymer per 100 parts of polyol. The method of claim 8, wherein the emulsion comprises 30 to 50 weight percent of the polymer. The method of claim 9, wherein the polymer is selected from the group consisting of styrene, acrylic acid, butyl acrylate, 2-hydroxy ethyl methacrylate, polyethylene glycol monomethacrylate, 2-ethylhexyl acrylate, and mixtures thereof. A method comprising an ethylenically unsaturated monomer. Rigid polyurethane foam prepared by the method according to claim 1. Rigid polyurethane foam prepared by the method according to claim 2. Rigid polyurethane foam prepared by the method according to claim 3. Rigid polyurethane foam prepared by the method according to claim 4. Rigid polyurethane foam prepared by the method according to claim 5. Rigid polyurethane foam prepared by the method according to claim 6. Rigid polyurethane foam prepared by the method according to claim 7. Rigid polyurethane foam prepared by the method according to claim 8. Rigid polyurethane foam prepared by the method according to claim 9. Rigid polyurethane foam prepared by the method of claim 10.