CN109422862B

CN109422862B - Rigid polyurethane foam systems and their use

Info

Publication number: CN109422862B
Application number: CN201710740383.XA
Authority: CN
Inventors: 魏文平; 郑春雷; 韦业奋
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Deutschland AG
Priority date: 2017-08-25
Filing date: 2017-08-25
Publication date: 2021-11-16
Anticipated expiration: 2037-08-25
Also published as: CN109422862A

Abstract

The invention relates to a rigid polyurethane foam system, comprising the following components: A) an isocyanate-reactive component; B) an organic polyisocyanate; C) a flame retardant; D) a catalyst; and E) a chemical blowing agent. The polyurethane rigid foam system has good fluidity, panel adhesion and flame retardance, and is very suitable for preparing discontinuous panels, especially refrigerated containers.

Description

Rigid polyurethane foam systems and their use

Technical Field

The invention belongs to the field of polyurethane. More particularly, the present invention relates to a rigid polyurethane foam system and its use.

Background

The polyurethane composite material prepared by the discontinuous process usually comprises a shell and polyurethane foam filled in the shell, adopts a processing process of firstly manufacturing plates and then assembling the plates, has high flexibility, and is widely applied to the fields of heat insulation and heat preservation plates such as containers, refrigeration houses, board houses, pipelines, air-conditioning heat insulation plates and the like.

The existing polyurethane composite material prepared by the discontinuous process is prepared by the following discontinuous process: and (3) placing the prefabricated shell in a mold, injecting polyurethane resin into the mold, closing the mold, foaming the polyurethane resin to form polyurethane foam, and demolding to obtain the polyurethane composite material. Polyurethane resins are typically formed from the reaction of an isocyanate component and a polyol component.

In the discontinuous plate preparation process, the fluidity and the adhesiveness of a foam system are technical focuses all the time. If the fluidity of the foam system is not good, the foam density distribution of the product is poor, and the defects of cell deformation, bubbles and the like are easy to occur at the flowing end of the foam. The adhesive property of the foam system directly influences the occurrence probability of bubbles of the foam composite material, the service life of a product and the like.

HCFC141b is commonly used as a foaming agent in the current discontinuous sheet preparation process, but HCFC141b will be gradually eliminated due to ODP (potential for ozone layer damage) and GWP (potential for greenhouse effect).

CN101044180A proposes a method for preparing rigid polyurethane foam, which aims at improving the compatibility of cyclopentane in composite polyether, thereby improving the applicability of foam system. In this patent, high hydroxyl number, high functionality polyethers are used in large amounts in combination with low hydroxyl number TDA or TMP initiated polyethers to improve the compatibility of the system with pentane. But there is no mention of how to improve the problems of adhesion, bubbles, etc. in the practical use of the foam system.

US5895792A discloses a process for the preparation of rigid polyurethane foams using cyclopentane as the blowing agent, in which an aromatic amine-initiated polyether is used in combination with a high functionality polyether, primarily for the purpose of increasing the thermal degradation temperature of the foam, but this patent does not mention how to increase the flow and adhesion of non-HCFC 141b blowing agent systems.

Flame Retardants generally act as Flame Retardants in Rigid Polyurethane foams, and the impact of different Flame Retardants and the amount of Flame retardant on the Flame retardant effect of the Foam is reported in the literature (composite of different Phosphorus based Flame Retardants in a formed Polyurethane Foam for the Production of Insulation Materials, Heiko rubber, John Sawaya, CPI 2011). However, there is no mention in these reports of how various flame retardants help to improve foam bonding.

Therefore, from the industrial practice, a rigid polyurethane foam system is needed, which has excellent fluidity and cohesiveness, thereby having better practical production process performance, and meanwhile, the foam system has good flame retardant effect, and meets the requirements of subsequent welding and installation of a discontinuous composite structure.

Disclosure of Invention

The invention aims to provide a polyurethane rigid foam system which has excellent fluidity, adhesiveness and flame retardancy.

The technical problem to be solved by the invention is solved by the following technical scheme:

according to a first aspect of the present invention, there is provided a rigid polyurethane foam system comprising the following components:

A) an isocyanate-reactive component comprising the following polyether polyols:

a1) a first polyether polyol: a difunctional polyether having a hydroxyl value of less than 200mgKOH/g, a viscosity of less than 200mPa.s at 25 ℃ and a content of 5 to 20 parts by weight;

a2) a second polyether polyol: a high functionality low hydroxyl value polyether having a functionality of >4, a hydroxyl value of <400mgKOH/g, a viscosity at 25 ℃ of <15000mPa · s, in an amount of 15 to 65 parts by weight;

a3) a third polyether polyol: a high-functionality high-hydroxyl-value polyether having a functionality of >4, a hydroxyl value of >400mgKOH/g, a viscosity of >15000 mPa.s and <25000 mPa.s at 25 ℃, in an amount of 10 to 40 parts by weight;

a4) a fourth polyether polyol: an aromatic ammonia-initiated polyether having a functionality of <4.5, a hydroxyl value of <400mgKOH/g, a viscosity at 25 ℃ of <30000mPa · s, in an amount of 10 to 35 parts by weight;

the total amount of the polyether polyol is 100 parts by weight;

B) the organic polyisocyanate takes polyether polyol and moisture contained in the polyurethane rigid foam system as references, and the isocyanate index of the organic polyisocyanate is 1.10-1.40;

C) the flame retardant comprises 5-25 parts by weight of halogen flame retardant and non-halogen flame retardant, wherein the non-halogen flame retardant accounts for 5-40% by weight of the whole flame retardant;

D) a catalyst comprising one or more of a foaming catalyst, a gelling catalyst and a trimerization catalyst in an amount of 0.80 to 2.00 parts by weight; and

E) a chemical blowing agent in an amount of 1.00 to 3.00 weight percent based on the weight of the A) isocyanate-reactive component.

According to a second aspect of the present invention, there is provided a rigid polyurethane foam obtained by the reaction of the above rigid polyurethane foam system.

According to a third aspect of the present invention, there is provided a process for producing the above rigid polyurethane foam, comprising the steps of:

i) the following components were mixed and stirred uniformly to obtain a polyol premix composition:

A) an isocyanate-reactive component comprising the following polyether polyols:

the total amount of the polyether polyol is 100 parts by weight;

E) a chemical blowing agent in an amount of 1.00 to 3.00 wt% based on the weight of A) the isocyanate-reactive component;

ii) mixing the following B) organic polyisocyanate with the polyol premix composition to obtain a polyurethane rigid foam system:

B) an organic polyisocyanate, wherein the isocyanate index of the organic polyisocyanate is 1.10-1.40 based on polyether polyol and water contained in the polyol premix composition;

iii) reacting the rigid polyurethane foam system to obtain a rigid polyurethane foam.

According to a fourth aspect of the present invention, there is provided a polyurethane composite material comprising a shell and the above polyurethane rigid foam filled in the shell.

According to a fifth aspect of the present invention, there is provided a method for preparing the above polyurethane composite, comprising the steps of:

i) providing a housing having a cavity;

ii) supplying the above polyurethane rigid foam system into the cavity of the housing; and

iii) subjecting the rigid polyurethane foam system to a foaming reaction to obtain a polyurethane composite.

The polyurethane rigid foam system has good flowing property, has good bonding property with metal (such as iron, aluminum and the like), FRP, PS, ABS and other panels, can reach the C-grade flame retardant standard of GB 8410-2006, and is very suitable for preparing discontinuous panels, especially refrigerated containers. The core density of the polyurethane rigid foam can reach 35-70kg/m³The foam closed-cell rate can reach 85-98%.

Detailed Description

The following describes specific embodiments for carrying out the present invention.

A) an isocyanate-reactive component comprising the following polyether polyols:

a1) a first polyether polyol: a difunctional polyether having a hydroxyl value of less than 200mg KOH/g, a viscosity of less than 200mPa.s at 25 ℃ and a content of 5 to 20 parts by weight;

the total amount of the polyether polyol is 100 parts by weight;

B) the organic polyisocyanate takes polyether and moisture contained in the polyurethane rigid foam system as references, and the isocyanate index of the organic polyisocyanate is 1.10-1.40;

E) 1.00 to 3.00 wt.% of a chemical blowing agent, based on the weight of A) the isocyanate-reactive component.

When used in the present invention, the "polyether polyol" has a definition well known to those skilled in the art and can be prepared by known processes, for example, by reacting an olefin oxide with an initiator in the presence of a catalyst.

The first polyether polyols a1) useful in the present invention have a functionality of 1.6 to 2.4, preferably a hydroxyl number of 60 to 140mgKOH/g, preferably in an amount of 5 to 15 parts by weight.

When used in the present invention, unless otherwise indicated, functionality and hydroxyl number refer to average functionality and average hydroxyl number.

Methods for measuring hydroxyl number are well known to the person skilled in the art, for example in Houben Weyl, Methoden der Organischen Chemie, vol.XIV/2Makromolekulare Stoffe, p.17, Georg Thieme Verlag; as disclosed in Stuttgart 1963, the entire contents of which are incorporated herein by reference.

In some embodiments of the present invention, the first polyether polyol is selected from 1, 2-propanediol, 1, 3-propanediol-initiated polyether polyols.

In a preferred embodiment, the first polyether polyol is selected from 1, 2-propanediol initiated propylene oxide based polyether polyols.

The second polyether polyol a2) useful in the present invention preferably contains 30 to 50 parts by weight of a high-functionality low-hydroxyl-number polyether.

The third polyether polyol a3) useful in the present invention preferably contains 25 to 35 parts by weight of a high functionality high hydroxyl number polyether.

In some embodiments of the present invention, the third polyether polyol is selected from sucrose, sorbitol initiated polyether polyols.

More preferably, the second and third polyether polyols are selected from sucrose-initiated propylene oxide-based polyether polyols.

In one embodiment of the present invention, the first polyether polyol, the second polyether polyol, and the third polyether polyol are each selected from propylene oxide based polyether polyols.

The fourth polyether polyol a4) which can be used in the present invention is preferably selected from polyether polyols starting from diphenylmethanediamine and/or toluenediamine having a functionality of from 3.6 to 4.4 and a hydroxyl value of 290-370mgKOH/g, preferably in an amount of from 15 to 25 parts by weight.

In one embodiment of the present invention, the fourth polyether polyol is selected from propylene oxide based polyether polyols starting with diphenylmethane diamine. The isocyanate-reactive composition comprising the above polyether polyol has a functionality of from 3.5 to 6, preferably from 4.0 to 5.5, a hydroxyl value of from 280-450mgKOH/g, preferably from 290-350 mgKOH/g.

The isocyanate-reactive component may also include a polyol selected from polyester polyols, polycarbonate polyols, and mixtures thereof in an amount of 0 to 30 parts by weight.

The polyester polyol is prepared by reacting dicarboxylic acid or dicarboxylic anhydride with polyhydric alcohol. The dicarboxylic acids are preferably, but not limited to, aliphatic carboxylic acids having 2 to 12 carbon atoms, such as: succinic acid, malonic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, mixtures thereof. The dibasic acid anhydride is preferably, but not limited to, phthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, and a mixture thereof. The polyhydric alcohol is preferably, but not limited to, ethylene glycol, diethylene glycol, 1, 2-propanediol, 1, 3-propanediol, dipropylene glycol, 1, 3-methylpropanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, neopentylglycol, 1, 10-decanediol, glycerol, trimethylolpropane, and a mixture thereof. The polyester polyol also comprises polyester polyol prepared from lactone. The polyester polyol prepared from lactone is preferably, but not limited to, epsilon-caprolactone.

The polycarbonate polyol is preferably, but not limited to, a polycarbonate diol. The polycarbonate diol may be prepared by reacting a diol with a dialkyl or diaryl carbonate or phosgene. The diol is preferably, but not limited to, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, diethylene glycol, trioxymethylene glycol, and mixtures thereof. The dialkyl or diaryl carbonate is preferably, but not limited to, diphenyl carbonate.

The organic polyisocyanates of component B) include organic diisocyanates which may be any aliphatic, cycloaliphatic or aromatic isocyanates known for the preparation of polyurethanes.

The organic polyisocyanate of component B) has an index of 1.10 to 1.40, preferably 1.15 to 1.30.

The index of the organic isocyanate referred to in the specification of the present application means an isocyanate index, which is generally based on the polyether polyol and water contained in the polyurethane rigid foam system or the polyol premix composition. It should be understood that since the organic isocyanate is moisture sensitive, the organic isocyanate raw material is substantially free of moisture, and the polyether polyol and moisture contained in the polyurethane rigid foam system are substantially the same as the polyether polyol and moisture contained in the polyol premix composition.

As examples of organic diisocyanates there may be mentioned: 2,2 '-diphenylmethane diisocyanate, 2, 4-diphenylmethane diisocyanate, 4' -diphenylmethane diisocyanate; diphenylmethane diisocyanate homologues having three or more rings (polymeric MDI); hydrogenated diphenylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), oligomers of isophorone diisocyanate; 2, 4-toluene diisocyanate (2,4-TDI), 2, 6-toluene diisocyanate; tetramethylene diisocyanate, oligomers of tetramethylene diisocyanate; hexamethylene Diisocyanate (HDI), oligomers of hexamethylene diisocyanate; naphthalene Diisocyanate (NDI).

In embodiments of the present invention, the organic polyisocyanate includes isocyanates based on diphenylmethane diisocyanate, especially those containing polymeric MDI.

The functionality of the organic polyisocyanate is preferably from 1.9 to 3.5, particularly preferably from 2.5 to 3.3.

The organic polyisocyanate preferably has a viscosity of 100-600 mPas, particularly preferably 150-300 mPas.

The viscosity described in the present specification was determined at 25 ℃ in accordance with DIN 53019-1-3.

The organic isocyanate may be present in an amount of 20 to 60% by weight, relative to the total weight of the rigid polyurethane foam system.

Organic polyisocyanates polyisocyanate prepolymers may also be used. These polyisocyanate prepolymers can be obtained by reacting an excess of one or more of the above organic polyisocyanates with a compound having at least two isocyanate reactive groups at a temperature of, for example, 30 to 100 c, preferably 80 c.

The NCO content of the polyisocyanate prepolymers of the invention is preferably from 20 to 33% by weight, particularly preferably from 25 to 32% by weight.

The flame retardant used in the present invention includes halogen flame retardants and non-halogen flame retardants.

As halogen flame retardants that can be used, there may be mentioned, for example: TCPP (tris (2-chloropropyl) phosphate), TCEP (trichloroethyl phosphate), and the like.

As non-halogen flame retardants that can be used, mention may be made of, for example: TEP (triethyl phosphate), DMPP (dimethyl propylphosphonate), and the like.

The inventors have found through extensive studies that a composite flame retardant comprising a halogen flame retardant and a non-halogen flame retardant may change the strength of the foam, thereby affecting the adhesive properties of the foam.

The gel catalyst used in the present invention may be a gel catalyst commonly used in the field of polyurethane rigid foams, and there may be mentioned, for example: dimethylcyclohexylamine and dimethylbenzylamine.

The trimerization catalyst used in the present invention may be a trimerization catalyst commonly used in the field of rigid polyurethane foams, and examples which may be mentioned are: methyl ammonium salt, ethyl ammonium salt, octyl quaternary ammonium salt, hexahydro triazine and organic metal alkali.

The blowing catalyst used in the present invention may be a blowing catalyst commonly used in the field of rigid polyurethane foams, and there may be mentioned, for example: pentamethyldiethylenetriamine, bis-dimethylaminoethylether, N, N, N '-tetramethylethylenediamine, N, N, N' -tetramethylbutanediamine and tetramethylhexanediamine.

The skilled person will be able to select the type of catalyst used and to adjust the amount of catalyst used according to the intended use of the rigid polyurethane foam of the invention and the content of the isocyanate-reactive component and the organic isocyanate component in the formulation.

The chemical blowing agents which can be used in the present invention can be selected from various chemical blowing agents commonly used in the field of rigid polyurethane foams, such as water.

The content of chemical blowing agents is from 1.00 to 3.00% by weight, preferably from 1.30 to 2.50% by weight, based on the weight of A) the isocyanate-reactive component.

The polyurethane rigid foam system of the present invention may further comprise a physical blowing agent in an amount of 8 to 25 parts by weight based on 100 parts by weight of the polyether polyol.

The physical blowing agents which can be used in the present invention can be selected from various physical blowing agents commonly used in the field of rigid polyurethane foams, preferably but not limited to halogenated hydrocarbons (e.g., monochlorodifluoromethane, dichloromonofluoromethane, dichlorofluoromethane, trichlorofluoromethane, monofluorodichloroethane, pentafluorobutane, pentafluoropropane, chlorotrifluoropropene, hexafluorobutene), hydrocarbon compounds (e.g., butane, pentane, cyclopentane, hexane, cyclohexane, heptane), gases (e.g., air, carbon dioxide, nitrogen). The physical blowing agent is present in an amount of 8 to 25 parts by weight, preferably 9 to 20 parts by weight, based on 100 parts by weight of the isocyanate-reactive component.

The components that may be used to prepare the polyurethane foams of the present invention may also contain other adjuvants or additives commonly used in the art, such as surfactants and the like.

The surfactant is preferably, but not limited to, an ethylene oxide derivative of siloxane. The surfactant is used in an amount of 0.01 to 5% by weight based on the amount of all polyols (including both the polyol as a reaction component and the polyol used as a chain extender and the polyol used in other components) in the reaction system for preparing the polyurethane.

The core density of the polyurethane foam according to the invention can be up to 35-70kg/m³，

The closed cell rate of the polyurethane foam can reach 85-98%.

Among the components that can be used to prepare the polyurethane foams of the present invention, the isocyanate-reactive component A) has good compatibility with physical blowing agent components such as cyclopentane, thereby producing a foam having a uniform distribution. Meanwhile, the prepared polyurethane rigid foam also has good demolding performance and good surface quality.

According to a second aspect of the present invention, there is provided a rigid polyurethane foam obtained by reaction of the rigid polyurethane foam system.

A) an isocyanate-reactive component comprising the following polyether polyols:

the total amount of the polyether polyol is 100 parts by weight;

F) a chemical blowing agent in an amount of 1.00 to 3.00 wt% based on the weight of A) the isocyanate-reactive component;

B) an organic polyisocyanate, wherein the isocyanate index of the organic polyisocyanate is 1.10-1.40 based on polyether and moisture contained in the polyol premix composition;

The types and amounts of the above components are the same as those described above for the rigid polyurethane foam system.

The reaction of the rigid polyurethane foam system is generally carried out in an environment of 0 to 50 c, preferably 25 to 40 c.

The shell can be made of panel materials such as metal, plastic and composite boards.

The polyurethane composite may be selected from: a container top plate, side plates, bottom plate or door plate; a movable plate roof plate, a side plate or a bottom plate or a door plate; a top plate, a side plate or a bottom plate or a door plate of the refrigeration house; an air-conditioning heat insulation plate; a heat preservation pipeline.

i) providing a housing having a cavity;

iii) subjecting the polyurethane rigid foam system to a foaming reaction to obtain a polyurethane composite.

The temperature of the shell is usually kept between 28 and 40 ℃, and the temperature of the polyurethane rigid foam system raw material is 18 to 25 ℃. The method for preparing the polyurethane composite material is a discontinuous method.

In some embodiments of the invention, the cavity has a plate-like or hollow cylindrical shape.

In some embodiments of the present invention, a shell is prefabricated from panel materials such as metal, plastic, composite board, etc., then the joint of the shell is sealed, and the material injection hole and the exhaust hole are reserved, finally the shell is placed in a foaming mold, the rigid polyurethane foam system is injected into the cavity of the shell through the material injection holes of the mold and the shell, and after the foaming reaction of the rigid polyurethane foam system is completed, the foamed part is taken out of the mold, and then the polyurethane composite material is obtained.

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. In the event that a definition of a term in this specification conflicts with a meaning commonly understood by those skilled in the art to which the invention pertains, the definition set forth herein shall govern.

The present invention is illustrated by the following examples, but it should be understood that the scope of the present invention is not limited to these examples.

Examples

Description of the raw materials used in the examples:

difunctional polyether:

GR 210: polyether polyol, available from high bridge petrochemicals ltd, hydroxyl number: 100, viscosity: 160 mPas, functionality: 2.0;

high functionality low hydroxyl number polyethers:

desmophen 4030M: polyether polyol, available from kostew polymers ltd, hydroxyl number: 380, viscosity: 11250 mPas, functionality: 5.8;

GR 8231: polyether polyol, available from high bridge petrochemicals ltd, hydroxyl number: 310, viscosity: 1200 mPa · s, functionality: 4.3;

high functionality high hydroxyl number polyethers:

NJ 4502: polyether polyol, purchased from sentence, content, Ningwu New Material development Co., Ltd, hydroxyl value: 450, viscosity: 17000 mPas, functionality: 5.2;

NJ 6207: polyether polyol, purchased from sentence, content, Ningwu New Material development Co., Ltd, hydroxyl value: 460, viscosity: 16000 mPas, functionality 5.3;

aromatic ammonia-initiated polyethers:

z450: polyether polyol, available from taiwan ltd, china, science, having a hydroxyl value: 345, viscosity: 12000 mPas, functionality: 4.0;

flame retardant:

TCPP: halogen flame retardants available from yake science and technology ltd, Jiangsu;

TEP: non-halogen flame retardants available from yake science and technology ltd, Jiangsu;

surfactant (b):

l6920: purchased from mai-chu-gao-new materials (china) ltd;

foaming agent:

cyclopentane: purchased from maylon, guangzhou;

HFC 245 fa: purchased from Honeywell corporation;

LBA: purchased from Honeywell corporation;

catalyst:

dabco Polycat 41 (abbreviated as pc 41): polyurethane trimerization catalysts, available from air chemical products (china) ltd;

dabco polycat 8 (abbreviated pc 8): polyurethane gel catalysts, available from air chemical products (china) limited;

dabco polycat 5 (abbreviated pc 5): polyurethane foaming catalysts, available from air chemical products (china) limited;

organic polyisocyanate:

44v 20L: NCO content 31.5% by weight, available from Corcission polymers (China) Ltd.

The test methods used in the examples illustrate:

and (3) testing the fluidity: in the experiment, the fluidity of the foam system is tested by using the HSR flow pipe, and the higher the final height of the foam is, the better the fluidity of the system is.

And (3) testing the adhesion: and (3) adhering the steel plate (50 x 50mm) sprayed with the epoxy paint on a mould, foaming, taking out after foam molding, cutting along the edge of the steel plate, and testing the bonding strength of the foam and the plane material according to GB 9641.

And (3) testing the compressive strength: testing according to the GB8813 standard.

And (3) testing the heat conductivity coefficient: testing according to GB 3399.

And (3) testing the flame retardant property: testing according to GB8410 standard.

Examples 1 to 7 and comparative examples 1 to 7

Mixing the white components according to the formula shown in the table 1 by a premixing device, then mixing the white components with a physical foaming agent by a high-pressure premixing machine, finally carrying out closed-mold mixing and pouring with organic polyisocyanate (Desmodur 44V20L) by a high-pressure machine, and after the demolding time (about 30 minutes), opening the mold and taking out the foamed and molded discontinuous product.

Before pouring, a steel plate is prefabricated into a shell to form a plate-shaped cavity, then the joint part of the shell is sealed, a material injection hole and an exhaust hole are reserved, finally the shell is placed into a foaming forming die, a polyurethane rigid foam system is applied into the cavity of the shell through the die and the material injection hole of the shell, and after the foaming reaction of the polyurethane rigid foam system is completed, a foamed product is taken out of the die to obtain a discontinuous product.

Table 1

As can be seen from Table 1 above, the foam system of example 1 exhibited the best combination of flow, adhesion, foam strength, and thermal conductivity.

Table 2

It can be seen from table 2 that the formulation of example 4 performs best in terms of adhesion and other overall properties of the foam system, among the selection ratios of the different flame retardants.

Table 3

As can be seen from Table 3, the rigid polyurethane foam of the present invention is excellent in foam adhesion properties.

Through comparison of different foaming agents, the halogen flame retardant and the non-halogen flame retardant are used in combination in different foaming agent systems, so that the bonding strength of the foam system can be effectively improved.

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims

1. A rigid polyurethane foam system, characterized in that it comprises the following components:

A) an isocyanate-reactive component comprising the following polyether polyols:

the total amount of the polyether polyol is 100 parts by weight;

C) the flame retardant comprises 5-25 parts by weight of halogen flame retardant and non-halogen flame retardant, wherein the non-halogen flame retardant accounts for 5-50% by weight of the whole flame retardant;

2. The rigid polyurethane foam system according to claim 1, wherein the organic polyisocyanate is one or more components selected from the group consisting of: 2,2 '-diphenylmethane diisocyanate, 2, 4-diphenylmethane diisocyanate, 4, 4' -diphenylmethane diisocyanate; diphenylmethane diisocyanate homologues having three or more rings; polymeric MDI; hydrogenated diphenylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), oligomers of isophorone diisocyanate; 2, 4-toluene diisocyanate (2,4-TDI), 2, 6-toluene diisocyanate; tetramethylene diisocyanate, oligomers of tetramethylene diisocyanate; hexamethylene Diisocyanate (HDI), oligomers of hexamethylene diisocyanate; naphthalene Diisocyanate (NDI); and compounds obtained by reacting the above organic polyisocyanate with a compound having at least two isocyanate-reactive groups.

3. The rigid polyurethane foam system according to claim 1 or 2, wherein the first polyether polyol, the second polyether polyol and the third polyether polyol are each selected from propylene oxide-based polyether polyols.

4. The rigid polyurethane foam system according to claim 1 or 2, wherein the isocyanate-reactive component further comprises one or more polyols selected from the group consisting of polyester polyols, polycarbonate polyols, and mixtures thereof.

5. A rigid polyurethane foam obtained by the reaction of the rigid polyurethane foam system according to any one of claims 1 to 4.

6. A process for preparing the rigid polyurethane foam of claim 5, comprising the steps of:

A) an isocyanate-reactive component comprising the following polyether polyols:

the total amount of the polyether polyol is 100 parts by weight;

B) an organic polyisocyanate, wherein the isocyanate index of the organic polyisocyanate is 1.10-1.40 based on the polyether polyol and the moisture contained in the polyol premix composition;

7. A polyurethane composite material comprising a shell and the rigid polyurethane foam according to claim 5 filled in the shell.

8. The polyurethane composite of claim 7, wherein the housing is prepared from a panel material selected from the group consisting of metal, plastic, and composite sheet.

9. The polyurethane composite of claim 7, wherein the polyurethane composite is selected from the group consisting of: a container top plate, side plates, bottom plate or door plate; a movable plate roof plate, a side plate or a bottom plate or a door plate; a top plate, a side plate or a bottom plate or a door plate of the refrigeration house; an air-conditioning heat insulation plate; a heat preservation pipeline.

10. A process for preparing the polyurethane composite of any one of claims 7 to 9, characterized in that it comprises the following steps:

i) providing a housing having a cavity;

ii) supplying the rigid polyurethane foam system of any one of claims 1-4 into the cavity of the shell; and