CN114341225A

CN114341225A - Flame-retardant polyurethane foams with improved processability containing an optional blowing agent

Info

Publication number: CN114341225A
Application number: CN202080058268.4A
Authority: CN
Inventors: 徐建锋; S·E·梅农; 张红波; D·海尔斯曼; 赵连江; 聂祖宝
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2019-08-20
Filing date: 2020-08-12
Publication date: 2022-04-12
Also published as: JP2022546309A; WO2021032549A1; KR20220051846A

Abstract

The present invention relates to flame retardant Polyurethane (PU) foams having improved processability compared to conventional foams having similar flame retardant properties, or having better flame retardant properties compared to conventional foams at similar NCO-index. The invention also discloses a flame-retardant (FR) rigid foam prepared by the flame-retardant (FR) rigid foam, a preparation method thereof, a composite material containing the polyurethane foam and application of the composite material as a plate or a panel in the application of clean room refrigerators, cold storage boxes, roof plates, laminated plates and insulating plates; or as pipe insulation in injection pipe applications and injection pipe applications.

Description

Flame-retardant polyurethane foams with improved processability containing an optional blowing agent

Technical Field

The present invention relates to Polyurethane (PU) foam systems with improved processability; flame Retardant (FR) rigid foams prepared therefrom and methods of making the same; composite materials comprising the polyurethane foam and the use of the composite materials as boards or panels in clean room freezers, cold storage boxes, roof boards, laminates and insulation boards; or as pipe insulation in injection pipe applications and injection pipe applications.

Background

Polyurethane (PU) foams are suitable for a large number of applications, such as cushioning materials, thermal insulation materials, packaging, automobile dashboards or building materials.

In the foaming process of PU foam materials, physical and chemical foaming agents are used to achieve a certain foam material density. Physical blowing agents and chemical blowing agents differ in that physical blowing agents have a very high vapor pressure and evaporate in the polyurethane reaction of the polyol (present in the A component (C-A)) and the polyisocyanate (present in the B component (C-B)).

In most cases, the physical blowing agent is either dissolved in C-A or added separately at the customer end (customer side). Since many physical blowing agents have very high vapor pressures and are also flammable, premixing a larger amount of blowing agent in C-A or C-B can lead to safety risks. On the other hand, some customers do not have the ability to safely add combustible materials alone in the production process on their production line. Thus, only a limited number of customers can, for example, handle cyclopentane (cP) or n-pentane (nP).

In addition, conventional foaming agents widely used in the market at present are not environmentally friendly. Many blowing agents consist of chlorofluorocarbons (CFCs) or Hydrochlorofluorocarbons (HCFCs) which have been formed or may form tapes in the near future due to their contribution to ozone depletion. Therefore, solutions without CFC/HCFC are very advantageous.

HFCs (hydrofluorocarbons), especially HFOs (hydrofluoroolefins), are physical blowing agents which are more environmentally friendly. Therefore, they are not prohibited from entering the market. However, blowing agents such as LBA (trans-1-chloro-3, 3, 3-trifluoropropene) and 245fa (1,1,1,3, 3-pentafluoropropane) are not widely accepted in the market because of their price, and therefore their market acceptance is not high, for example, in the panel market which is driven by very high price.

In addition to physical blowing agents, chemical blowing agents are also used in PU foams. For example, Formic Acid (FA) and water (H)₂O) is the most common chemical blowing agent. FA and H₂And reacting the O with isocyanate groups to generate amine groups. Carbon dioxide (CO) is produced during this reaction₂) It acts as a true blowing agent. The newly generated amine groups can be further polymerized with another isocyanate group to form a urea structure. No chain termination occurs during the foaming reaction.

The acid groups being reactive with isocyanate groups to form anhydride intermediates and being reacted in CO₂Separation ofThe next reaction produces an amide structure. Also in this case, CO₂Will act as the actual blowing agent.

Monobasic acids will terminate the polymer chain, while diacids will extend the chain. The polyacid will cause further crosslinking of the PU structure.

The acid-based chemical blowing agent may be added to C-A or, if viscosity is suitable, may be added separately on-line. Some diacids and polyacids are on the market, but their acceptance is not high because they do not have any additional benefits over traditional blowing agents, nor are they cost competitive. In addition, some di-and polyacids have stability problems due to poor compatibility with C-A.

However, premixing of flammable blowing agents with high vapor pressure is a safety issue. The need to use alternative blowing agents that can be blended in C-a is more flexible to both the supplier and the customer who cannot handle flammable blowing agents or cannot add blowing agents separately on the production line.

Therefore, alternative blowing agents which are soluble in C-A and do not have any tendency to phase separate in C-A are very advantageous. In addition to good C-a compatibility, the development of alternative blowing agents also provides additional benefits to the resulting foam properties, such as better fire performance and processability, e.g., flow of liquid foams.

US5527876 describes the preparation of amides containing and elimination of CO by reacting polyfunctional isocyanates, carboxylic acids and optionally alcohols in the presence of tertiary amines, more particularly heteroaromatic amines₂The method of (3) plastic. By this solution, low density foams can be prepared at low processing temperatures (RT) in the presence of tertiary amines.

EP0711799a2 describes chlorofluorocarbon-free, urethane-containing moldings having a cellular core and an integral surface having a substantially nonporous surface, i.e. Polyurethane (PU) integral foams which are prepared by reacting the conventional starting components in the presence of blowing agents, catalysts and at least one substance selected from the group consisting of: (1) partially or fully neutralized homopolymers of monoethylenically unsaturated monocarboxylic acids, dicarboxylic acids, or their internal anhydrides; (2) a copolymer of (2i) a monoethylenically unsaturated monocarboxylic acid, dicarboxylic acid or its internal anhydride and (2ii) a carboxyl-free, monoethylenically unsaturated monomer copolymerizable with (2 i); and (3) (3i) a monoethylenically unsaturated monocarboxylic acid and/or a salt thereof, (3ii) a monoethylenically unsaturated dicarboxylic acid, a salt thereof and/or an internal anhydride thereof, and (3iii) a copolymer or graft copolymer of a carboxyl group-free monoethylenically unsaturated monomer copolymerizable with (3i) and (3ii), if necessary.

However, these documents do not show any benefits in terms of processability and other properties of the foam, whereas the current innovations can clearly show improvements in final foam properties (e.g. fire resistance) and processability (e.g. flowability).

Disclosure of Invention

It is an object of the present invention to overcome the above-mentioned problems of the prior art and to provide a flame retardant polyurethane foam system which shows better processability (fluidity of liquid foam) than conventional foams having similar flame retardant properties, or which has better flame retardant properties than conventional foams at similar NCO index. The LOI index of the flame retardant polyurethane in rigid form is at least 26%, preferably from 26% to 35%, more preferably from 27% to 31%, measured according to ISO4589-2: 1996.

Surprisingly, the inventors have found that the above object can be achieved by a polyurethane foam system consisting of:

A. a polyol composition; and

B. an isocyanate component;

wherein the polyol composition (A) comprises

a) Polyether polyols, polyester polyols, or mixtures thereof;

b) a catalyst;

c) at least one blowing agent, wherein the blowing agent comprises a carboxyl-terminated copolymer of diacid and alcohol (carboxyl-terminated copolymer of diacid and alcohol);

d) a flame retardant;

e) additives and/or auxiliaries.

For embodiments, the polyol composition (B) comprises from 5 to 40 weight percent, preferably from 10 to 30 weight percent, more preferably from 10 to 20 weight percent, of the carboxyl-terminated copolymer of diacid and alcohol, wherein the weight percent values of the polyol composition are based on the total weight of the polyol composition.

Further, the diacid component forming the carboxyl end copolymer is selected from the group consisting of C4 to C12 aliphatic carboxylic diacids, and in a preferred embodiment, the diacid component forming the carboxyl end is oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid.

Furthermore, the alcohol component forming the carboxyl end copolymer is selected from the group consisting of C2 to C6 diols or triols, and in a preferred embodiment the carboxyl end forming diol component is ethylene glycol, 1, 3-propanediol, propylene glycol, 1, 4-butanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 5-pentanediol, 1, 2-pentanediol, 1, 3-pentanediol or 1, 4-pentanediol; in another preferred embodiment, the triol component forming the carboxyl end-group copolymer is triethanolamine, glycerol or trimethylolpropane or a modification of the foregoing having a low degree of alkoxylation of up to 10.

The present disclosure also provides a method of making a polyurethane foam from the polyurethane foam system of the present invention. The process comprises providing a polyol composition (a); providing an isocyanate component (B); the polyol composition (a) and the isocyanate component (B) are reacted in a weight ratio such that the isocyanate (NCO) index is 200 to 400, preferably 220 to 330, more preferably 230 to 300.

In a preferred embodiment, the preparation process is a discontinuous system, while in another preferred embodiment, the preparation process is a continuous system.

In another aspect, the present disclosure provides flame retardant rigid polyurethane foams prepared according to the present invention.

In another aspect, the present disclosure provides a composite material comprising a flame retardant rigid polyurethane foam prepared according to the present invention.

The flame retardant composite can be used as a sheet or panel in clean room freezers, cold storage boxes, roof sheets, laminates, insulation sheets, and the like; or as pipe insulation in injection pipe applications and injection pipe applications.

Surprisingly, it has been found in the present application that by adding specific amounts of a carboxyl-terminated copolymer of a diacid and an alcohol to a polyurethane foam system, the polyurethane foam system exhibits good processability, while exhibiting good flame retardancy and mechanical properties.

Detailed Description

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein, the following terms have the meanings assigned to them below, unless otherwise indicated.

The articles "a" and "an" as used herein refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. For example, "an element" refers to one element or a plurality of elements.

All percentages (%) are "weight percent" unless otherwise indicated.

Unless otherwise indicated, temperature refers to room temperature and pressure refers to ambient pressure.

Unless otherwise indicated, solvents refer to all organic and inorganic solvents known to those skilled in the art, excluding any type of monomer molecule.

In various embodiments, a polyurethane foam system is provided. Typically, the system consists of a polyol composition (a) and an isocyanate component (B), wherein the polyol composition comprises

a) Polyether polyols, polyester polyols, or mixtures thereof;

b) a catalyst;

c) at least one blowing agent, wherein the blowing agent comprises a carboxyl-terminated copolymer of a diacid and an alcohol;

d) a flame retardant;

e) additives and/or auxiliaries.

The preparation of polyurethane foams has been described elsewhere but primarily involves polyether or polyester polyols and promoting the reaction of catalysts with isocyanates in the presence of suitable blowing agents.

The polyol composition comprises at least one compound having at least two isocyanate-reactive hydrogens, a urethane promoting catalyst, and at least one blowing agent comprising a carboxyl-terminated copolymer of a diacid and an alcohol. Preferably, the polyhydroxy compound having a functionality of 2 to 8, more preferably 3 to 6 and a hydroxyl number of 150 to 850, more preferably 200 to 600 is an example of a higher molecular weight compound having at least two reactive hydrogen atoms.

For example, polythioether polyols, polyesteramides, hydroxyl group-containing polyacetals, hydroxyl group-containing aliphatic polycarbonates, and polyester polyols and polyether polyols are preferred. Furthermore, a mixture of at least two of the above-mentioned polyhydroxy compounds may be used as long as their average hydroxyl value is within the above-mentioned range.

Suitable polyester polyols can be prepared, for example, from: organic dicarboxylic acids having 2 to 12 carbon atoms, preferably aliphatic dicarboxylic acids having 4 to 6 carbons, and polyhydric alcohols, preferably diols having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms. Examples of dicarboxylic acids include succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. The dicarboxylic acids can be used individually or in the form of mixtures. Instead of the free dicarboxylic acids, it is also possible to use the corresponding dicarboxylic acid derivatives, for example dicarboxylic acid monoesters or diesters of alcohols having 1 to 4 carbon atoms, or dicarboxylic anhydrides. Preference is given to dicarboxylic acid mixtures of succinic, glutaric and adipic acids, especially adipic acid, in a ratio of from 20 to 35:35 to 50:20 to 32 parts by weight. Examples of diols and polyols, especially diols, include ethylene glycol, diethylene glycol, 1, 2-and 1, 3-propanediol, dipropylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 10-decanediol, glycerol, and trimethylolpropane. Preference is given to ethylene glycol, diethylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol or mixtures of at least two of these diols, in particular mixtures of 1, 4-butanediol, 1, 5-pentanediol and 1, 6-hexanediol.

The polyester polyols can be prepared by polycondensation of organic polycarboxylic acids (for example aromatic or preferably aliphatic polycarboxylic acids and/or derivatives thereof) and polyols under the following conditions: the desired degree of polymerization, preferably less than 10, in particular less than 5, is achieved without catalyst or preferably in the presence of an esterification catalyst, preferably in an inert gas (e.g. nitrogen, carbon dioxide, helium, argon, etc.) atmosphere, at a temperature of from 150 ℃ to 250 ℃, preferably from 180 ℃ to 220 ℃, optionally under reduced pressure. In a preferred embodiment, the esterification mixture is subjected to polycondensation at the above-mentioned temperatures so that an acid number of from 80 to 30, preferably from 40 to 30, the polycondensation being carried out under normal pressure and then under a pressure of less than 500mbar, preferably from 50 to 150 mbar. Examples of suitable esterification catalysts include iron, cadmium, cobalt, lead, zinc, antimony, magnesium, titanium and tin catalysts in the form of metals, metal oxides or metal salts. However, the polycondensation can also be carried out in the liquid phase in the presence of diluents and/or entrainers (entraining agents), such as benzene, toluene, xylene or chlorobenzene, for azeotropic distillation of the condensed water.

For the preparation of the polyester polyols, the organic polycarboxylic acids and/or derivatives thereof are preferably polycondensed with the polyols in a molar ratio of 1:1 to 1.8, preferably 1:1.05 to 1.2.

The polyester polyols obtained preferably have a functionality of from 2 to 3 and a hydroxyl number of from 150 to 500, in particular from 200 to 400. However, polyether polyols obtainable by known processes are particularly preferably used as polyhydroxy compounds. For example, polyether polyols may be prepared by anionic polymerization of one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical: using an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an alkali metal alkoxide such as sodium methoxide, sodium ethoxide or potassium isopropoxide as catalyst and adding at least one initiator molecule containing from 2 to 8, preferably from 3 to 8, reactive hydrogens; alternatively, the polyether polyol may be prepared by cationic polymerization of one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene group: lewis acids (e.g., antimony pentachloride, boron trifluoride etherate, etc.) or bleaching earth are used as catalysts.

Suitable cyclic ethers and alkylene oxides include, for example, tetrahydrofuran, 1, 3-propylene oxide, 1, 2-and 2, 3-butylene oxide, styrene oxide, and preferably ethylene oxide and 1, 2-propylene oxide. The alkylene cyclic ethers and oxides can be used individually, alternately, one after the other or as mixtures. Examples of suitable initiator molecules include water, organic dicarboxylic acids such as succinic acid, adipic acid, phthalic acid and terephthalic acid, aliphatic and aromatic, optionally N-mono-, N-and N, N' -dialkyl-substituted diamines (having from 1 to 4 carbon atoms in the alkyl radical), for example optionally mono-and dialkyl-substituted ethylenediamine, diethylenetriamine, triethylenetetramine, 1, 3-propylenediamine, 1, 3-and 1, 4-butylenediamine, 1,2-, 1,3-, 1,4-, 1, 5-and 1, 6-hexamethylenediamine, phenylenediamine, 2,3-, 2, 4-and 2, 6-toluenediamine and 4,4' -, 2,4' -and 2,2' -diaminodiphenylmethane.

Suitable initiator molecules also include alkanolamines, such as ethanolamine, diethanolamine, N-methyl-and N-ethylethanolamine, N-methyl-and N-ethyldiethanolamine and triethanolamine, and ammonia.

Preference is given to polyhydric, in particular dihydric and/or trihydric alcohols, such as ethylene glycol, 1, 2-and 1, 3-propanediol, diethylene glycol, dipropylene glycol, 1, 4-butanediol, 1, 6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose.

The polyether polyols preferably have a functionality of from 3 to 8, in particular from 3 to 6, and a hydroxyl number of from 300 to 850, preferably from 350 to 800.

Also suitable as polyether polyols are melamine polyether polyol dispersions according to U.S. patent No. 4,293,657; a polymer polyether polyol dispersion according to U.S. Pat. No. 4,305,861, prepared from a polyepoxide and an epoxy resin curing agent in the presence of a polyether polyol; dispersions of aromatic polyesters in polyols according to U.S. Pat. No. 4,435,537; dispersions of organic and/or inorganic fillers in polyols according to U.S. Pat. No. 4,243,755; polyurea polyether polyol dispersions according to DE a 312402, tris- (hydroxyalkyl) isocyanurate polyether polyol dispersions according to U.S. Pat. No. 4,514,526, microcrystalline suspensions according to U.S. Pat. No. 4,560,708, the details of which are to be regarded as part of the disclosure of this patent and are incorporated herein by reference.

As with the polyester polyols, the polyether polyols may also be used individually or in the form of mixtures. Furthermore, they can be mixed with the above-described dispersion, suspension or polyester polyols and also hydroxyl-containing polyesteramides, polyacetals and/or polycarbonates.

Examples of hydroxyl-containing polyacetals which may be used include, for example, the compounds which can be prepared from glycols such as diethylene glycol, triethylene glycol, 4' -dihydroxyethoxydiphenyldimethylmethane, hexanediol and formaldehyde. Suitable polyacetals can also be prepared by polymerizing cyclic acetals.

Suitable hydroxyl-containing polycarbonates include those of the known type, for example those obtained by reaction of diols, for example 1, 3-propanediol, 1, 4-butanediol and/or 1, 6-hexanediol, diethylene glycol, triethylene glycol or tetraethylene glycol and diaryl carbonates (for example diphenyl carbonate) or phosgene.

Polyesteramides include the predominantly linear polycondensates obtained from polybasic saturated and/or unsaturated carboxylic acids and their anhydrides and aminoalcohols or mixtures of polyols and aminoalcohols and/or polyamines.

Polyurethane foams may be prepared with or without chain extenders and/or crosslinkers. Suitable chain extenders and/or crosslinkers preferably include alkanolamines, more preferably diols and/or triols. Typical examples are alkanolamines such as ethanolamine and/or isopropanolamine; dialkanolamines, such as diethanolamine, N-methyl-diethanolamine, N-ethyldiethanolamine, diisopropanolamine; trialkanolamines, such as triethanolamine, triisopropanolamine; and addition products of ethylene oxide or 1, 2-propylene oxide; alkylenediamines having 2 to 6 carbon atoms in the alkylene group such as N, N '-tetrakis (2-hydroxyethyl) -ethylenediamine and N, N' -tetrakis (2-hydroxypropyl) ethylenediamine; aliphatic, cycloaliphatic and/or araliphatic diols having from 2 to 14, more preferably from 4 to 10, carbon atoms, such as ethylene glycol, 1, 3-propanediol, 1, 10-decanediol, o-, m-, p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol, preferably 1, 4-butanediol, 1, 6-hexanediol and bis (2-hydroxyethyl) hydroquinone; triols, such as 1,2, 4-and 1,3, 5-trihydroxycyclohexane, glycerol and trimethylolpropane; low molecular weight, hydroxyl-containing polyalkylene oxides based on ethylene oxide and/or 1, 2-propylene oxide and aromatic diamines such as tolylenediamine and/or diaminodiphenylmethane together with the aforementioned alkanolamines, diols and/or triols as initiator molecules.

If chain extenders, crosslinkers or mixtures thereof are used in the preparation of the polyurethane foams, these are advantageously used in amounts of up to 20% by weight, more preferably from 2 to 10% by weight, based on the weight of the polyol composition.

Suitable catalysts (b) include, in particular, compounds which greatly accelerate the reaction of the hydroxyl-containing compound component and optionally with the polyisocyanate. Examples include organometallic compounds, preferably organotin compounds, for example tin (II) salts of organic carboxylic acids, such as tin (II) acetate, tin (II) octoate, tin (II) ethylhexanoate and tin (II) laurate, and dialkyltin (IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate. Another preferred metal compound, such as a potassium compound, is selected from the following: potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium benzoate, potassium formate, potassium acetate, potassium propionate, potassium butyrate, potassium valerate, potassium hexanoate, potassium octanoate, potassium 2-ethylhexanoate, potassium neodecanoate, potassium decanoate, potassium salicylate, potassium laurate, potassium oleate, potassium maleate, potassium citrate, potassium diacetate, potassium methoxide, potassium cellulose, potassium carboxymethylcellulose, potassium hyaluronate, potassium alginate, potassium gluconate, and any combination thereof.

The metal compounds are used alone or preferably in combination with strongly basic amines. Examples include amines such as 2, 3-dimethyl-3, 4,5, 6-tetrahydropyrimidine, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, N, N, N ', N' -tetramethylethylenediamine, N, N, N ', N' -tetramethylbutanediamine or-hexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethylether, bis (dimethylaminopropyl) urea, dimethylpiperazine, 1, 2-dimethylimidazole, 1-azabicyclo [3.3.0] octane, preferably 1, 4-diaza-bicyclo [2.2.2] octane, and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyl-and N-ethyldiethanolamine, and dimethylethanolamine.

Suitable catalysts include tris- (dialkylamino) -s-hexahydrotriazine, especially tris (N, N-dimethylaminopropyl) -s-hexahydrotriazine, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, alkali metal hydroxides such as sodium hydroxide, and alkali metal alcoholates such as sodium methylate and potassium isopropoxide and alkali metal salts of long chain fatty acids having 10 to 20 carbon atoms and optionally OH side groups. One skilled in the art can select a particular catalyst or combination of catalysts.

The blowing agent (C) disclosed herein comprises a carboxyl-terminated copolymer of a diacid, preferably selected from the group consisting of C4-C12 aliphatic carboxylic diacids, and an alcohol, preferably selected from the group consisting of C2 to C6 diols or triols.

Suitable diacids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid, wherein the diacid is preferably adipic acid.

Suitable diols include ethylene glycol, 1, 3-propanediol, propylene glycol, 1, 4-butanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 5-pentanediol, 1, 2-pentanediol, 1, 3-pentanediol, and 1, 4-pentanediol; also, suitable triols include triethanolamine, glycerol or trimethylolpropane or modifications of the foregoing components having a low degree of alkoxylation of up to 10. Preferably, the alcohol is selected from diethylene glycol and trimethylolpropane.

In various embodiments, the carboxyl-terminated copolymer has a molecular weight of from 200 to 2000, preferably from 150 to 1300; the acid number is from 50 to 600, preferably from 90 to 600.

The acid number was determined by titration and calculated as follows,

acid value of ((F)_n×56100gmol))M_n

F_nIs defined as the functionality

M_nIs defined as the number average molecular weight

The polymerization process is a conventional esterification reaction carried out in excess diacid monomer.

In another embodiment, the carboxyl-terminated copolymer may be used alone or in combination with other blowing agents. Other blowing agents include physical blowing agents such as alkanes (e.g., pentane), fluorocarbon-containing hydrocarbons, hydrofluorocarbons, chlorocarbons, chlorofluorocarbons, hydrochlorofluorocarbons and chemical blowing agents such as water.

Suitable flame retardants (d) for the purposes of the present invention are preferably liquid organic phosphorus compounds, for example halogen-free organic phosphates, such as triethyl phosphate (TEP), halogenated phosphates, such as tris (1-chloro-2-propyl) phosphate (TCPP) and tris (2-chloroethyl) phosphate (TCEP), and also organic phosphonates, such as dimethyl methylphosphonate (DMMP), Dimethylpropane (DMPP), or solids, such as ammonium polyphosphate (APP) and red phosphorus. Furthermore, as flame retardants, halogenated compounds such as halogenated polyols and solids such as expanded graphite and melamine are suitable.

Optionally, other additives and/or auxiliaries (e) may be added to the reaction mixture to prepare the polyurethane foam. Examples include surfactants, foam stabilizers, cell regulators, fillers, dyes, pigments, hydrolysis preventers, fungistats and bacteriostats.

Examples of suitable surfactants are compounds which serve to support the homogenization of the starting material and which can also regulate the cell structure of the plastic. Specific examples are sulfonates, for example alkali metal or ammonium salts of fatty acids such as oleic or stearic acid, dodecylbenzenesulfonic or dinaphthylmethanedisulfonic acid and ricinoleic acid; foam stabilizers, for example siloxane-alkylene oxide copolymers and other organopolysiloxanes, oxyethylated alkylphenols, oxyethylated fatty alcohols, paraffin oils, castor oil esters, ricinoleic acid esters, turkey red oil and peanut oil; and cell regulators such as paraffin, fatty alcohol, and dimethylpolysiloxane. The surfactant is generally used in an amount of 0.01 to 5 parts by weight, based on 100 parts by weight of the polyol composition. In addition, oligomeric acrylates having polyalkylene oxide and fluoroalkane side groups are also suitable for improving the emulsifying effect, the cell structure and/or for stabilizing the foam. These surfactants are generally used in amounts of 0.01 to 5% by weight, based on the weight of the polyol composition. For the purposes of the present invention, fillers are conventional organic and inorganic fillers and reinforcing agents. Specific examples are inorganic fillers, such as silicate minerals, for example, phyllosilicates (phyllosilicates) such as antigorite, serpentine, hornblende, amphibole, chrysotile and talc; metal oxides such as kaolin, alumina, titanium oxide and iron oxide; metal salts such as chalk, barite (baryte) and inorganic pigments such as cadmium sulfide, zinc sulfide and glass, etc.; kaolin (china clay), aluminium silicate, coprecipitates of barium sulfate and aluminium silicate, and natural and synthetic fibrous minerals such as wollastonite, metals and glass fibres of various lengths. Examples of suitable organic fillers are carbon black, melamine, rosin, cyclopentadiene resins, cellulose fibers, polyamide fibers, polyacrylonitrile fibers, polyurethane fibers and polyester fibers based on aromatic and/or aliphatic dicarboxylic acid esters, in particular carbon fibers. The inorganic and organic fillers may be used alone or as a mixture, and may be incorporated in the polyol composition or the isocyanate side in an amount of 0.5 to 40% by weight, based on the weight of the components (polyol and isocyanate).

The isocyanate component (B) of the present invention includes essentially all aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyisocyanates known. Specific examples include alkylene diisocyanates having 4 to 12 carbons in the alkylene group, such as 1, 12-dodecane diisocyanate, 2-ethyl-1, 4-tetramethylene diisocyanate, 2-methyl-1, 5-pentamethylene diisocyanate, 1, 4-tetramethylene diisocyanate, preferably 1, 6-hexamethylene diisocyanate; cycloaliphatic diisocyanates, for example 1, 3-and 1, 4-cyclohexane diisocyanate and any mixtures of these isomers, 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 2, 4-and 2, 6-hexahydrotoluylene diisocyanate and the corresponding isomer mixtures, 4,4'-2,2' -and 2,4 '-dicyclohexylmethane diisocyanate and the corresponding isomer mixtures, preferably aromatic diisocyanates and polyisocyanates such as 2, 4-and 2, 6-toluylene diisocyanate and the corresponding isomer mixtures, 4,4' -, 2,4 '-and 2,2' -diphenylmethane diisocyanate and the corresponding isomer mixtures, mixtures of 4,4 '-and 2,4' -diphenylmethane diisocyanate and polyphenylene polymethylene polyisocyanate (polymeric MDI), and mixtures of polymeric MDI and toluene diisocyanate. The organic diisocyanates and polyisocyanates can be used individually or in the form of mixtures.

The polyurethane foams of the present invention can be prepared batchwise (discontinuously) or continuously according to the prepolymer process or more preferably according to the one-pot process with the aid of conventional mixing equipment. The process comprises providing a polyol composition (a); providing an isocyanate component (B); the polyol composition (a) and the isocyanate component (B) are reacted in a weight ratio such that the isocyanate (NCO) index is 200 to 400, preferably 220 to 330, more preferably 230 to 300.

In the context of the present invention, the following terms have the following meanings:

1) isocyanate index or NCO index or index: the ratio of NCO groups to isocyanate-reactive hydrogen atoms present in the formulation, given as a percentage:

[ NCO ] x 100 (%)/[ active hydrogen ]

In other words, the NCO-index represents the percentage of isocyanate actually used in a formulation relative to the amount of isocyanate theoretically required (the amount used to react with the isocyanate-reactive hydrogen used in a formulation).

It should be observed that the isocyanate index as used herein is considered from the point of view of the actual foaming process involving the isocyanate ingredient and the isocyanate-reactive ingredients. Any isocyanate groups consumed in a preliminary step to prepare the modified polyisocyanate (including isocyanate derivatives referred to in the art as prepolymers) or any active hydrogens consumed in a preliminary step (e.g., reacted with isocyanate to form a modified polyol or polyamine) are not taken into account in calculating the isocyanate index. Only the free isocyanate groups and the free isocyanate-reactive hydrogens (including those of the water) present at the actual foaming stage are taken into account.

In another aspect, the present invention provides a flame retardant rigid polyurethane foam prepared according to the above process. Discontinuous systems will be prepared in a discontinuous process by single or two point injection methods and used in applications such as refrigerated containers, roof decks and the like. The liquid foam needs to fill the entire mold before gelation begins. Therefore, a system with a long gel time is needed. A continuous system will be prepared in a continuous process on one double conveyor line. The prepared panel will be used in, for example, freezer applications. The reactivity of such a continuous process is much faster than a non-continuous process, since the panels need to be processed and cut in a short time.

The flame retardant composite can be used as a sheet or panel in clean room freezers, cold storage boxes, roof sheets, laminates, insulation sheeting and other applications; or as pipe insulation in injection pipe applications and injection pipe applications.

Examples

Measuring and testing method

The measurement and test methods are shown in table 1.

TABLE 1 measurement and test standards

Performance of	Unit of	Test standard
			Density of	g/L	DIN EN ISO 845:2006
Compressive strength	N/mm²	ISO 844:2014
			Dimensional stability	％	DIN EN 1604:2007
Fluidity of the resin	cm/g	Inner part
			Fire test B2	Cm	DIN 4102-1:1998
Limiting Oxygen Index (LOI)	％	ISO 4589-2:2017

Furthermore, the flow properties were measured as follows: the liquid foam was applied in a flow die with dimensions of 100cm by 15cm by 3 cm. The liquid foam is placed at one end of a flow die. During the reaction, the temperature inside the mold was maintained at 57 ℃ for 30 minutes. After the foam was held in the mold for 30 minutes, the cured foam was removed from the mold. The average expanded length of the foam and the weight of the foam were measured. The ratio between length and weight was then calculated to determine the flowability in cm/g of each foam composition. Thus, the larger the calculated ratio, the better the flowability of the liquid foam.

Material

The materials used in the examples are as follows.

Polyol 1, polyester polyol (PO group), with Glycerol-EO as initiator, OHV 240

Polyol 2, polyether polyol (PO group), with glycerol as initiator, OHV 230

Polyol 3, polyether polyol (PO based), starting with sorbitol, OHV 490

Polyol 4, polyether polyol (PO group), DEG as initiator, OHV 215

Acid A1, carboxyl-terminated copolymer of adipic acid and diethylene glycol (esterification), acid number 188, Mn 896

Acid A2, carboxyl-terminated copolymer (esterified) of adipic acid and trimethylolpropane (TMP550), acid number 240, Mn 701

PMDI, 4,4' -diphenylmethane diisocyanate (MDI), oligomers containing high functionality and isomers, from Pasteur

M 20S

Synthetic acid A1 (bifunctional)

The chemical route to produce this chemical is a copolymer/esterification reaction of adipic acid and diethylene glycol. The two monomers were copolymerized in a weight ratio of adipic acid to DEG of 2:1 to ensure that all chain ends were terminated with adipic acid. The reaction was catalyzed with 0.0025 wt% titanium butoxide (TTB). The reaction mixture was slowly heated to 200 ℃ in the reactor under a water separator. The water separation was continued after maintaining the temperature at 200 ℃. After a total of about 5 hours (heating and maintaining the temperature at 200 ℃) and after the correct acid number was reached, the vacuum was released and the reaction mixture was cooled to room temperature.

Synthetic acid A2 (trifunctional group)

The chemical route to this chemical is the copolymer/esterification reaction of adipic acid and trimethylolpropane (TMP 550). Two monomers were copolymerized in a weight ratio of 1.433 parts TMP550 to 1 part adipic acid. The reaction was catalyzed with 0.03 wt.% TTB. The reactor was equipped with a Vigreux column and a Dean-Stark type condenser to collect the condensation product. During the first half of the synthesis, the apparatus was continuously purged with nitrogen to limit oxidation and promote the transport of water vapor. While stirring, the mixture was heated to 120 ℃ using a heating mantle. The catalyst was added when the temperature of the mixture reached 120 ℃. The reaction temperature was gradually increased to maintain the by-products formed by distillation. After 8 hours at 230 ℃ the polymer was cooled and discharged from the reactor.

Discontinuous system

The composition of the ester-type discontinuous system with blowing agent acid A1 according to the invention is shown in Table 2 in columns of example 1 and example 1. In the column named control 1 in table 2, the composition of the reference system is shown.

These three compositions were used to prepare box mold (box mold) foams having dimensions of 40cm by 9 cm. During the reaction, after the foam was injected into the mold for 30 minutes, the cured foam was demolded while controlling the in-mold temperature of control 1 at 60 ℃ and the in-mold temperatures of examples 1 and 2 at 55 ℃.

TABLE 2 formulation and Properties of the discontinuous System

Component A	Control group 1	Example 1	Example 2
				Polyol 1	25	21	23
Polyol 2	9	5	5
				Polyol 3	10	10	15
Acid A1	-	20	20
				Polyol 4	5	-	-
Flame retardant TCPP	30	25	25
				Flame retardant TEP	5.3	5	5
Organic silicon surfactant	2.15	2.2	2.2
				2-hydroxypropyl trimethyl ammonium formate	1	1	1
(2- ((2- (dimethylamino) ethyl) methylamino) ethanol	0.1	0.1	0.1
				Potassium salt based catalysts	0.2	1.5	1.1
N- (2-hydroxy-5-nonylphenyl) -methyl-N-methylglycine salt	0.8	0.8	0.8
				Water (W)	1.5	1.6	1.6
Pentane (pentane)	10	5	6
				B component
PMDI	170	194	160
				NCO index	300	300	240
Performance of
				Density (g/L)	40.6	41.2	39.7
Compressive strength (N/mm)²)	0.25	0.25	0.23
				Dimensional stability (%)	<1％	<3％	<1％
Fluidity (cm/g)	0.498	0.512	0.528
				Fireproofing test B2(cm)	13	8	12
LOI(％)	26.6	29.2	27.4

The NCO index is one of the main factors for improving the fireproof performance of PU foam by a foam system. For the composition of control 1, an index of 300 was chosen to achieve a B2 value of 13cm and an LOI value of 26.6%. In the composition of example 1 in table 1, the polymeric acid a1 was used in 20 parts, except for minor changes. The composite index is also 300. Thus, the B2 value can be reduced to 8cm and the LOI value increased to 29.2%. The index was reduced to 240 in example 2. The resulting B2 was similar to the baseline system at 12cm, with an LOI of slightly better 27.4%. However, for example 2 the flowability of 0.528cm/g can be significantly increased compared to the baseline system (0.498 g/cm).

In summary, the fire performance can be improved if the acid A1 (example 1) is used, with the same NCO index. Furthermore, the results of example 2 show that the fire performance can be kept similar or even better, while the index can be greatly reduced. Furthermore, the flowability of the system (example 2) shows excellent properties.

Furthermore, the processing temperature can be lowered by 5 ℃ without causing any defects in the flow or curing of the foam.

The polyol composition (a) is stable in the absence of water if the polymeric acid is present in the range of 0 to 30 wt% based on the total weight of the polyol composition (a).

The mixing ratio was adjusted in table 3, and further, the NCO index was maintained at 240 to 300. The index is designed to be lower as the polymeric acid content increases. The formulation composition and related properties are summarized in table 3.

TABLE 3 formulation and Properties of different acid A1 concentrations in the discontinuous System

In example 3, only 5 parts of acid A1 were used. However, the fire performance may already be improved. In addition, an improvement in flowability was detected.

The NCO index of formulation example 3, example 4 and example 5 was gradually decreased from 273 to 240, while that of control 1 was 300. Even if the index is greatly reduced, the fire-proof performance is still greatly improved. In addition, the fluidity is also improved.

Continuous system

The two compositions were foamed in separate box-shaped moulds measuring 40cm by 9 cm. The mold temperature was 60 ℃. After 30 minutes, the slabstock foam was demolded and used to test all mechanical properties. The composition and properties of the continuous system are shown in table 4.

Table 4: formulation and performance of the continuous system: comparison of systems with and without alternative blowing agents

Similar to the discontinuous system, the index in the continuous system can be reduced from 380 in control 2 to 330 in example 6. Even with a decreasing index, the fire performance is still similar. On the other hand, the fluidity of the reference system increases.

Overall, the benefits of discontinuous systems are more pronounced, but benefits such as improved flow and the possibility of achieving very good fire performance at lower indices can also be detected in continuous systems.

Trifunctional blowing agent acid A2

After evaluation of difunctional blowing agent acid A1, trifunctional acid A2 was also evaluated. The compositions and properties are shown in table 5. The composition of the reference system is shown in column 1 of control and the system with trifunctional blowing agent acid A2 is shown in column 7 of example. Both systems were foamed in box molds (40cm x 9cm) at a mold temperature of 60 ℃ with a demolding time of 30 minutes. These blocks will be used to test all mechanical properties.

TABLE 5 formulation and Properties of trifunctional acid A2

Like acid A1, the trifunctional blowing agent acid A2 also exhibits fire performance and flow benefits.

Claims

1. A polyurethane foam system consisting of:

A. a polyol composition; and

B. an isocyanate component;

wherein the polyol composition (A) comprises

a) Polyether polyols, polyester polyols, or mixtures thereof;

b) a catalyst;

d) a flame retardant;

e) additives and/or auxiliaries.

2. The polyurethane foam system of claim 1 wherein the polyol composition (a) comprises from 5 to 40 weight percent, preferably from 10 to 30 weight percent, more preferably from 10 to 20 weight percent, of the carboxyl-terminated copolymer of diacid and alcohol, wherein the weight percent values of the polyol composition are based on the total weight of the polyol composition.

3. The polyurethane foam system of claim 1 or 2 wherein the diacid is a C4 to C12 aliphatic carboxylic diacid and the alcohol is a C2 to C6 diol or triol.

4. The polyurethane foam system of any one of claims 1-3, wherein the diacid is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

5. The polyurethane foam system of any one of claims 1 to 4, wherein the alcohol is selected from the group consisting of diols including ethylene glycol, 1, 3-propanediol, propylene glycol, 1, 4-butanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 5-pentanediol, 1, 2-pentanediol, 1, 3-pentanediol, and 1, 4-pentanediol.

6. The polyurethane foam system of any one of claims 1 to 4 wherein the alcohol is selected from triols including triethanolamine, glycerol or trimethylolpropane or modifications of the foregoing components having a low degree of alkoxylation of up to 10.

7. The polyurethane foam system of any one of claims 1 to 6, the carboxyl-terminated copolymer having a molecular weight of from 200 to 2000, preferably from 150 to 1300.

8. The polyurethane foam system of any one of claims 1 to 6, the carboxyl-terminated copolymer having an acid number of from 50 to 600, preferably from 90 to 600.

9. The polyurethane foam system of claim 1 wherein the isocyanate component (B) is selected from aliphatic, cycloaliphatic, araliphatic and/or aromatic isocyanates, such as tri-, tetra-, penta-, hexa-, hepta-and/or octamethylene diisocyanate; 2-methylpentamethylene 1, 5-diisocyanate; 2-ethylbutylene 1, 4-diisocyanate; pentamethylene 1, 5-diisocyanate; butylene 1, 4-diisocyanate; 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI); 1, 4-and/or 1, 3-bis (isocyanatomethyl) cyclohexane (HXDI); cyclohexane 1, 4-diisocyanate; 1-methylcyclohexane 2, 4-and/or 2, 6-diisocyanate and/or dicyclohexylmethane 4,4' -, 2,4' -and 2,2' -diisocyanate; diphenylmethane 2,2' -, 2,4' -and/or 4,4' -diisocyanate (MDI); polymeric MDI; naphthalene 1, 5-diisocyanate (NDI); toluene 2, 4-and/or 2, 6-diisocyanate (TDI); 3,3' -dimethyldiphenyl diisocyanate; 1, 2-diphenylethane diisocyanate and/or phenylene diisocyanate.

10. The polyurethane foam system of claim 1 wherein catalyst (b) comprises an amine-based catalyst and an organometallic compound-based catalyst.

11. The polyurethane foam system of claim 1, wherein the blowing agent (c) further comprises other chemical blowing agents and/or physical blowing agents.

12. The polyurethane foam system of claim 11, wherein the chemical blowing agent comprises water, formic acid and the physical blowing agent comprises pentane, HFC.

13. The polyurethane foam system of claim 1, wherein flame retardant (d) comprises at least one phosphorus-containing flame retardant that is a derivative of phosphoric acid, phosphonic acid, and/or phosphinic acid.

14. The polyurethane foam system of claim 1, wherein the component (e) comprises a silicone surfactant.

15. A method of making a polyurethane foam from the polyurethane foam system of any one of claims 1 to 14, the method comprising the steps of:

-providing a polyol composition (a);

-providing an isocyanate component (B); and

-reacting the polyol composition (A) and the isocyanate component (B) in a weight ratio such that the isocyanate (NCO) index is 200-.

16. The method of claim 15, wherein the manufacturing process is a discontinuous system or a continuous system.

17. Flame-retardant rigid polyurethane foam prepared according to the process of claim 15 or 16.

18. The flame retardant rigid polyurethane foam according to claim 17, wherein the foam has an LOI value of at least 26%, preferably from 26% to 35%, more preferably from 27% to 31%, measured according to ISO4589-2: 1996.

19. The flame retardant rigid polyurethane foam according to claim 17, wherein the foam has a flow value (cm/g) of at least 0.4cm/g, preferably at least 0.5 cm/g.

20. A composite comprising the flame retardant rigid polyurethane foam according to any one of claims 17 to 19.

21. Use of the composite of claim 20 as a sheet or panel in clean room cold stores, freezers, roofing, laminating and insulating board applications; or as pipe insulation in injection pipe applications and injection pipe applications.