CN111635597A

CN111635597A - Polystyrene heat-insulating material and preparation method thereof

Info

Publication number: CN111635597A
Application number: CN202010534493.2A
Authority: CN
Inventors: 潘鸽; 丁明明; 许东华; 石彤非
Original assignee: Changchun Institute of Applied Chemistry of CAS
Current assignee: Changchun Institute of Applied Chemistry of CAS
Priority date: 2020-06-12
Filing date: 2020-06-12
Publication date: 2020-09-08

Abstract

The invention provides a polystyrene heat-insulating material and a preparation method thereof. The polystyrene thermal insulation material provided by the invention is a coated flame-retardant thermal insulation material, the surface of polystyrene foam is coated with a flame retardant layer, the flame retardant layer comprises expandable graphite, a cationic adhesive, an inorganic flame retardant, inorganic nanoparticles and positively charged magnetic nanoparticles which are matched in a certain proportion, wherein the cationic adhesive is prepared from water-based polyurethane, acrylamide, a cationic monomer, an initiator, a cross-linking agent and water in a certain proportion, and the prepared cationic adhesive is introduced into the flame retardant layer in a certain proportion and is matched with other components of the flame retardant layer, so that the flame-retardant capability of the polystyrene foam can be effectively improved, and the mechanical property of the polystyrene foam can be improved.

Description

Polystyrene heat-insulating material and preparation method thereof

Technical Field

The invention relates to the field of composite materials, in particular to a polystyrene thermal insulation material and a preparation method thereof.

Background

Polystyrene is a common polymer material, and the yield of polystyrene is only second to that of polymers such as polyolefin, polyvinyl chloride and the like. And can be widely applied to the fields of home decoration, packaging materials, automobile interior decoration, building heat preservation, aviation and the like. In the field of building heat preservation, polystyrene foam materials are often used for building roofs, pipelines, walls and floors, and are low in cost and excellent in performance. The polystyrene foam material has large specific surface area, the internal structure of the material is in a cellular shape, the material is extremely easy to burn, flame quickly diffuses after burning, and a large amount of toxic gas can be released in the burning process. Therefore, it is necessary to prepare an environment-friendly polystyrene insulation board with high flame retardancy, which meets the requirement of environment protection and also meets the standard of flame retardancy grade.

The traditional halogen-containing flame retardant has large smoke amount during combustion, emits toxic gas and seriously endangers the life safety of people, and the Intumescent Flame Retardant (IFR) has the characteristics of no halogen, no toxicity, no pollution and the like, and is a novel and efficient environment-friendly flame retardant. Intumescent flame retardants include P-N intumescent flame retardant systems and intumescent graphite flame retardants (EG). The expanded graphite is a flame retardant with good plastic material, and has the characteristics of obvious flame retardant effect, good heat preservation effect, high expansion rate, good waterproofness and the like. The flame retardant can achieve ideal flame retardant effect when used alone or mixed with other flame retardants. When a fire disaster occurs, the intumescent flame retardant suffocates the flame through the instantaneous increase of the volume, and simultaneously absorbs a large amount of environmental heat in the expansion process, so as to achieve the effect of reducing the temperature of the system and further achieve the purpose of flame retardance and fire prevention. However, because the expandable graphite has low strength and very weak adhesion, how to improve the strength and adhesion of the intumescent graphite flame retardant is a problem to be solved in industrial production. At present, methods for improving the adhesion force are in the forms of clamping grooves, surface concave-convex, connecting blocks and the like, but the methods cannot fundamentally solve the problems.

In order to improve the flame retardance of the polystyrene foam insulation board, the matrix material can be improved in the modes of flame retardance of the body, coating flame retardance, surface coating flame retardance and the like. Wherein, the bulk flame retardant is to form a microscopic multiphase dispersion system by the flame retardant in a dispersed phase form and polystyrene base; for example, patent application CN 104895205 a adopts a bulk flame retardant method, polystyrene and graphite powder are mixed and foamed to prepare a graphite polymer insulation board, however, the product obtained by the method has the problems of uneven graphite distribution, higher thermal conductivity, unsatisfactory expansion coefficient, difficulty in controlling product quality and the like. The surface-coated flame retardant is to coat a flame retardant layer on the surface of a substrate to improve flame retardancy; for example, patent CN 20529446U adopts a surface coating method, and a layer of flame retardant material is coated on the surface of the polystyrene board, although a certain flame retardant effect can be achieved, the limitation is large because the surface coating is damaged or fails under the action of long-term flame. The coating flame-retardant process is originally developed by Monsanto company and Shell company in the United states, the flame retardant is coated on the surface of Expanded Polystyrene (EPS) beads in a blending mode, and the method is simple to operate, high in flame-retardant efficiency and strong in adjustability. By adjusting the material type, content, proportion and the like of the coating layer, the flame retardant property, mechanical property and thermal insulation property of the polystyrene flame retardant foam material can be effectively regulated and controlled, so as to meet the requirements of the market and practical application.

For example, patent application CN 106117856 a utilizes a coating flame retardant method to prepare a fireproof polystyrene insulation board, which adopts materials such as urea-formaldehyde resin, alkyd resin, aluminum hydroxide, ammonium polyphosphate and the like as flame retardants, the flame retardant performance is obviously improved, but the flame retardants will undergo a curing reaction at room temperature, so that problems of non-uniform coating of the flame retardants, large energy consumption of mixing process and the like can be generated in actual production. The patent application CN 102391588A prepares a high-flame-retardant heat-preservation polystyrene foam heat-preservation plate by a method of coating polystyrene particles with a flame retardant; the flame retardant is an inorganic-organic composite flame retardant, phenolic resin, expandable graphite and red phosphorus are used as flame retardant coatings and are coated on the surface of polystyrene foam, but the flame retardant is poor in binding property with polystyrene, so that the mechanical property of a product is poor, and the problems of crushing, falling and the like of the flame retardant can occur in the combustion process. The above prior arts are polystyrene foams prepared by a coating flame retardant method, but the problems of flame retardancy, environmental protection, mechanical properties, curing rate and the like are not well solved in the patent.

Patents CN203583688U, CN206495346U, CN208105555U, etc. all adopt a groove mode to add a flame retardant layer on the polystyrene outer layer to improve the flame retardancy of the material, the method is complex to operate, and has the problems of insecure outer layer material, easy falling off, etc., which cannot improve the flame retardancy fundamentally.

Disclosure of Invention

In view of the above, the present invention aims to provide a polystyrene thermal insulation material and a preparation method thereof. The polystyrene heat-insulating material provided by the invention can effectively improve the mechanical strength, flame retardant property and heat-insulating property of the material, and has high environmental protection property.

The invention provides a polystyrene heat-insulating material, which comprises: the flame retardant coating comprises polystyrene foam and a flame retardant layer coated on the surface of the polystyrene foam;

the flame retardant layer comprises the following components in parts by mass:

the cationic adhesive is formed by the following raw materials in parts by mass:

preferably, the cationic monomer is selected from one or more of dimethyl diallyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride and methacryloyloxyethyl trimethyl ammonium chloride.

Preferably, the cationic adhesive is prepared by the following steps:

mixing water-based polyurethane, acrylamide, a cationic monomer, an initiator, a cross-linking agent and water, and heating for reaction to obtain the cationic adhesive.

Preferably, the inorganic flame retardant is selected from one or more of magnesium hydroxide, aluminum hydroxide and red phosphorus;

the inorganic nano particles are selected from one or more of graphene, carbon nano tubes, layered nano montmorillonite, clay, kaolin, cellulose, calcium carbonate, silicon dioxide and carbon black.

Preferably, the positively charged magnetic nanoparticles are selected from one or more of layered nano montmorillonite treated by quaternary ammonium salt, iron-coated modified titanium dioxide, ionic liquid modified carbon nanotubes, graphene oxide and surface cation modified nanocellulose.

Preferably, the polystyrene foam is formed by foaming polystyrene particles;

the polystyrene particles are EPS particles with negative charges on the surface and/or neutral EPS particles.

Preferably, the EPS particles having a negative charge on the surface are prepared by:

s1, mixing water, an emulsifier, a dispersant, a suspending agent, a styrene monomer, an initiator and a plasticizer for reaction to form an intermediate product;

s2, mixing the intermediate product with CaCO₃、Ca₃(PO₄)₂And mixing the emulsifier and the anionic monomer, introducing pentane into the system, and heating for reaction to obtain the EPS particles with negative charges on the surfaces.

Preferably, the first and second liquid crystal materials are,

in the step S1:

the reaction temperature is 80-90 ℃, and the reaction time is 1-2 h;

in the step S2:

the anionic monomer is selected from one or more of sulfonate, carboxylate and phosphate;

the sulfonate is selected from one or more of hydroxyethane sulfonate, aryl alkane sulfonate, lignosulfonate and styrene sulfonate;

the carboxylate is selected from carboxylate with carboxyl, sulfonic group, amino or polyoxyethylene group as side chain group;

the phosphate is selected from one or more of alkyl aryl phosphate, alkylphenol polyoxyethylene ether phosphate, alkyl alcohol amide phosphate, imidazoline phosphate and siloxane phosphate;

the temperature-rising reaction comprises the following steps: firstly heating to 106-108 ℃, controlling the pressure to be 0.6-0.8 MPa, and reacting for 2-3 h; then heating to 110-114 ℃ and reacting for 3-3.5 h.

The invention also provides a preparation method of the polystyrene heat-insulating material in the technical scheme, which comprises the following steps:

a) carrying out primary foaming on the polystyrene particles to obtain polystyrene foam;

b) mixing the polystyrene foam with a flame retardant solution and then drying to obtain polystyrene foam coated with a flame retardant layer;

c) carrying out secondary foaming on the polystyrene foam coated with the flame retardant layer to obtain a polystyrene heat-insulating material;

the flame retardant solution comprises the following components in parts by mass:

preferably, the first and second liquid crystal materials are,

in the step a):

the primary foaming is steam foaming; the steam conditions are: the temperature is 96-120 ℃, the pressure is 0.2-0.4 MPa, and the time is 1-2 h;

in the step b):

the mass ratio of the polystyrene foam to the flame retardant solution is 1: 1-1.5;

the drying temperature is 25-50 ℃;

in the step c):

the secondary foaming is steam foaming; the steam foaming conditions are as follows: the temperature is 96-120 ℃, the pressure is 0.08-0.15 MPa, and the time is 0.5-1 h.

The polystyrene heat-insulating material provided by the invention is a coated flame-retardant heat-insulating material, the surface of polystyrene foam is coated with a flame retardant layer, the flame retardant layer comprises expandable graphite, a cationic adhesive, an inorganic flame retardant, inorganic nanoparticles and positively charged magnetic nanoparticles which are matched in a certain proportion, wherein the cationic adhesive is prepared from water-based polyurethane, acrylamide, a cationic monomer, an initiator, a cross-linking agent and water in a certain proportion, and the cationic adhesive is prepared, introduced into the flame retardant layer in a certain proportion and matched with other components of the flame retardant layer, so that the flame-retardant capability of the polystyrene foam can be effectively improved, and the mechanical property of the material and the adhesive force of the material of the flame-retardant layer are improved.

The experimental result shows that the oxygen index of the polystyrene heat-insulating material provided by the invention reaches more than 35% (standard GB/T2406.93); the fire-proof grade is A grade (standard GB 8624-97); the compression strength reaches more than 0.33KPa, and the tensile strength reaches more than 0.39KPa (standard GB 9641-1988); the thermal conductivity is below 0.033W/(mK) (standard GB/T10801.2-2002).

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of a process for preparing a polystyrene thermal insulation material provided by the present invention;

fig. 2 is an appearance schematic diagram of the polystyrene insulation boards obtained in embodiments 1, 4, and 6.

Detailed Description

the flame retardant layer comprises the following components in parts by mass:

the polystyrene thermal insulation material provided by the invention is a coated flame-retardant thermal insulation material, the surface of polystyrene foam is coated with a flame retardant layer, the flame retardant layer comprises expandable graphite, a cationic adhesive, an inorganic flame retardant, inorganic nanoparticles and positively charged magnetic nanoparticles which are matched in a certain proportion, wherein the cationic adhesive is prepared from water-based polyurethane, acrylamide, a cationic monomer, an initiator, a cross-linking agent and water in a certain proportion, and the prepared cationic adhesive is introduced into the flame retardant layer in a certain proportion and is matched with other components of the flame retardant layer, so that the flame-retardant capability of the polystyrene foam can be effectively improved, and the mechanical property of the polystyrene foam can be improved.

In the present invention, the polystyrene foam is formed by foaming polystyrene particles. The polystyrene particles are EPS particles with negative charges on the surface and/or neutral EPS particles.

The neutral EPS particles are commercial EPS products, and the commercial EPS products with the particle size of 1.0-3.0mm and the foaming rate of 40-60 times are preferred; more preferably one or more of PKF-301XS, PKF-401XS and PKF-501XS of the PKF-XS series, available from Ningxingda New materials for foam plastics, Inc.

The EPS particles with negative charges on the surfaces are self-made EPS particles and are prepared by the following steps:

Regarding step S1:

the emulsifier is preferably sodium dodecyl benzene sulfonate. The dispersing agent is preferably one or more of calcium phosphate, polyvinyl alcohol, hydroxyethyl cellulose and methyl cellulose. The suspending agent is preferably one or more of diatomite and talcum powder. The initiator is preferably one or more of dibenzoyl peroxide, tert-butyl peroxybenzoate and azobisisobutyronitrile. The plasticizer is preferably tributyl phosphate. During the mixing process, stirring is preferably accompanied; more specifically, under the condition of stirring, respectively adding an emulsifier, a dispersant, a suspending agent, a styrene monomer, an initiator and a plasticizer into water, and uniformly mixing. After the materials are added, heating for reaction; the temperature rise is pre-selected to be 80-90 ℃, and the time of the heat preservation reaction is preferably 1-2 h. In the above treatment process, the monomer is firstly broken into smaller droplets under strong mechanical stirring to form smaller micro-beads, then the smaller micro-beads are gradually polymerized to form larger droplets to be dispersed in an aqueous phase medium, then a dispersing agent is added, solid powder of the dispersing agent is uniformly suspended in the aqueous phase, and finally the smaller droplets can be continuously polymerized into larger droplets among the powder to form an intermediate product.

Regarding step S2:

after the intermediate product is obtained in step S1, CaCO is added in sequence₃、Ca₃(PO₄)₂The particle size and the dispersity of the product are adjusted and controlled by introducing the two and specific adding steps and sequences, and a certain amount of CaCO is added firstly₃The very small suspended particles are brought together and grown to about 1mm size, and Ca is added₃(PO₄)₂The pH value is adjusted to be subacidity and the dispersion effect is exerted, so that the solid powder is uniformly suspended in the water phase.

Thereafter, the emulsifier and the anionic monomer are added. The emulsifier is preferably sodium dodecyl benzene sulfonate. The anionic monomer is preferably one or more of sulfonate, carboxylate and phosphate. Wherein the sulfonate is preferably one or more of hydroxyethane sulfonate, aryl alkane sulfonate, lignosulfonate and styrene sulfonate; the above sulfonate is more preferably a sodium sulfonate salt; in some embodiments, sodium styrene sulfonate or sodium p-styrene sulfonate. The carboxylate is preferably a carboxylate in which a side chain group is a carboxyl group, a sulfonic group, an amino group or a polyoxyethylene group; more preferably one or more of sodium polyoxyethylene ether carboxylate and sodium N-acylaminocarboxylate. The phosphate is selected from one or more of alkyl aryl phosphate, alkylphenol polyoxyethylene ether phosphate, alkyl alcohol amide phosphate, imidazoline phosphate and siloxane phosphate; more preferably one or more of tetrasodium vinylphosphonate and aluminum phosphite. The addition of the above anionic monomers during the polymerization process results in a large amount of negative charges on the surface of the product.

After the materials are added, pentane is pressed into the reaction system by an air compressor to carry out heating reaction. The temperature-raising reaction particularly preferably includes: firstly heating to 106-108 ℃, controlling the pressure to be 0.6-0.8 MPa, and reacting for 2-3 h; then heating to 110-114 ℃ and reacting for 3-3.5 h. In the present invention, it is preferable to further perform cooling, filtration, washing and drying after the above-mentioned reaction, thereby obtaining expandable polystyrene particles having a negative charge on the surface. The obtained polystyrene particles with negative charges on the surface have the particle size of 1.0-1.3 mm and the specific gravity of 80-100 kg/m³The expansion ratio is 60 to 70 times.

For the self-made polystyrene particles with negative charges on the surfaces, the mass ratio of all the raw materials in the preparation process is preferably as follows:

wherein, the emulsifiers are used in the step S1 and the step S2, and the total amount of the emulsifiers is 1-1.5 parts.

In the present invention, for the above two types of EPS particles: the polystyrene heat-insulating material product is prepared by self-made EPS particles with negative charges on the surfaces and commercially-available commercial neutral EPS particles, more preferably by adopting the self-made EPS particles with negative charges on the surfaces, the surfaces of the polystyrene heat-insulating material product have a large amount of negative charges, the polystyrene heat-insulating material product has stronger binding capacity with flame retardant layer components, the flame retardance of the material can be better improved, and compared with the commercial EPS particles, the oxygen index is obviously improved.

In the invention, the flame retardant layer comprises the following components in parts by mass:

the expandable graphite is an organic flame retardant, the source of which is not particularly limited, and the expandable graphite is a general commercial product. The expandable graphite is used in an amount of 10 to 30 parts, and in some embodiments, 25 parts.

The inorganic flame retardant is preferably one or more of magnesium hydroxide, aluminum hydroxide and red phosphorus. The source of the inorganic flame retardant is not particularly limited, and may be a commercially available product. In the present invention, the inorganic flame retardant is used in an amount of 10 to 20 parts, and in some embodiments, 15 or 25 parts.

The inorganic nano particles are inorganic particles with unmodified surfaces, and are preferably one or more of graphene, carbon nano tubes, layered nano montmorillonite, clay, kaolin, cellulose, calcium carbonate, silicon dioxide and carbon black. Wherein, the graphene is preferably 1-3nm thick, 3-5um in diameter, 2-5 layers in number and 500m in specific surface area²Multilayer graphene per gram. The carbon nano-tube is preferably a carbon nano-tube with the diameter of 6-8nm and the length of 50 um. The layered nano montmorillonite is preferably the layered nano montmorillonite with the granularity of 400 meshes. The clay is preferably nano clay with the particle size of 1-2 um. The kaolin is preferably kaolin with a particle size of 1-2 um. The cellulose is preferably nano-cellulose with the particle size of 100 nm. The calcium carbonate is preferably nano calcium carbonate with the particle size of 60-80 nm. The silica is preferably a hydrophilic fumed silica, more preferably a fumed silica having a particle size of 5 to 10 nm. The carbon black is preferably nano carbon black particles with the particle size of 5-10 nm. In the present invention, the inorganic nanoparticles are used in an amount of 0 to 10 parts, preferably more than 0 part, and in some embodiments, in an amount of 5 parts or 10 parts.

The positively charged magnetic nanoparticles are inorganic particles with positive charges on the surfaces of the inorganic particles, and are preferably one or more of layered nano montmorillonite treated by quaternary ammonium salt, iron-coated modified titanium dioxide, ionic liquid modified carbon nanotubes, graphene oxide and surface cation modified nanocellulose. The quaternary ammonium salt treated layered nano montmorillonite can be obtained by the following specific method: melting and blending the layered nano montmorillonite and a quaternary ammonium salt polymer matrix with certain molecular mass by a melting and blending method; wherein the weight average molecular weight of the quaternary ammonium salt is preferably 1400-5000; the quaternary ammonium salt is preferably one or more of dimethyl diallyl ammonium chloride, glycidyl trialkyl quaternary ammonium salt and Gemini quaternary ammonium salt; the mass ratio of the quaternary ammonium salt to the layered nano montmorillonite is (1.5-2) to 1. The preparation method of the iron-coated modified titanium dioxide is not particularly limited, and may be a conventional coating process well known to those skilled in the art. The ionic liquid modified carbon nanotube can be obtained by the following specific method: melting and blending the carbon nano tube, the polyvinylidene fluoride and the ionic liquid by a melting and blending method; wherein the ionic liquid is preferably one or more of 1-butyl-3-methylimidazole hexafluorophosphate, 1-ethyl-3-methylimidazole tetrafluoroborate and 1-allyl-3-methylimidazole hexafluorophosphate. The mass ratio of the polyvinylidene fluoride to the carbon nano tubes is preferably (1-1.5) to 1, and the mass ratio of the ionic liquid to the carbon nano tubes is preferably (1-1.5) to 1. The surface cation-modified nanocellulose can be obtained by: treating the nano-cellulose by an esterification, etherification or addition reagent to introduce a tertiary amine, quaternary ammonium salt or quaternary phosphonium salt structure into a chain segment of the nano-cellulose. In the present invention, the amount of the positively charged magnetic nanoparticles is 0 to 5 parts, more preferably greater than 0 part, and in some embodiments of the present invention, 5 parts. The inorganic nanoparticles and the positively charged magnetic nanoparticles are introduced, so that the interface effect with a polymer matrix can be enhanced, the plasticizing enhancement effect is achieved, the compatibility of the flame retardant and polystyrene foam can be improved, meanwhile, the nanoparticles and the intumescent flame retardant have extremely strong synergistic effect, and the flame retardant efficiency of the intumescent flame retardant is effectively improved.

wherein, the cation monomer is preferably one or more of dimethyl diallyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride and methacryloyloxyethyl trimethyl ammonium chloride. The initiator is preferably one or more of azobisisobutyronitrile and dimethyl azobisisobutyrate. The cross-linking agent is preferably one or more of diethanolamine, monoisopropanolamine and diisopropanolamine.

The preparation method for preparing the cationic adhesive by adopting the raw materials comprises the following steps: mixing water-based polyurethane, acrylamide, a cationic monomer, an initiator, a cross-linking agent and water, and heating for reaction to obtain the cationic adhesive. The temperature is preferably raised to 80-85 ℃, and the time of the heat preservation reaction is preferably 2-3 h; and after the reaction, forming the cationic adhesive with a polyurethane-acrylamide composite structure. The preparation method is more preferably as follows: uniformly mixing water, waterborne polyurethane, acrylamide and an initiator, adding a cross-linking agent and a cationic monomer, and heating for reaction.

According to the invention, the specific cationic adhesive is introduced into the flame retardant layer, so that the binding property between the flame retardant and polystyrene foam can be effectively enhanced, and the flame retardant effect is improved; when the polystyrene foam is prepared from the self-made EPS particles with the surface to be negatively charged, the bonding property of a flame retardant system and the polystyrene foam can be further enhanced through the attraction effect of positive and negative charges, so that the flame retardant effect is further improved; the cationic adhesive is non-toxic and environment-friendly (does not contain harmful substances such as benzene, toluene, formaldehyde and the like), has stable chemical properties at room temperature, can be stored for a long time, and has excellent comprehensive performance.

The polystyrene heat-insulating material provided by the invention is introduced with the cationic adhesive, and the inorganic nano particles and the positively charged magnetic nano particles, and the environment-friendly polystyrene heat-insulating material with high strength, high flame retardance and high heat insulation is obtained through the combination characteristic of the cationic adhesive between the intumescent flame retardant and the polystyrene foam and the synergistic effect of the nano particles and the intumescent flame retardant.

with respect to step a):

the types of the polystyrene particles are the same as those in the above technical scheme, and are not described again here. The primary foaming is preferably steam foaming. The steam conditions are preferably: the temperature is 96-120 ℃, the pressure is 0.2-0.4 MPa, and the time is 1-2 h. After primary foaming, the polystyrene foaming body is obtained.

With respect to step b):

the types, the using amounts, the sources and the like of the expandable graphite, the cationic adhesive, the inorganic flame retardant, the inorganic nanoparticles and the positively charged magnetic nanoparticles are consistent with those in the technical scheme, and are not repeated herein. The mass ratio of the polystyrene foam to the flame retardant solution is preferably 1 to (1-1.5). The mixing is preferably stirring mixing, and specifically, stirring mixing can be performed by a mixer; the stirring speed is preferably 500-1000 rad/min; the stirring time is preferably 10-20 min. After stirring and mixing, attaching a layer of uniform and compact flame retardant shell on the surface of the polystyrene foam, and then drying; the drying temperature is preferably 25-50 ℃. And drying to obtain the polystyrene foam coated with the flame retardant layer.

With respect to step c):

and b) obtaining the polystyrene foam coated with the flame retardant layer, and foaming the polystyrene foam, namely performing secondary foaming. The secondary foaming is preferably steam foaming. The steam conditions are preferably: the temperature is 96-120 ℃, the pressure is 0.08-0.15 MPa, and the time is 1-2 h. In the secondary foaming process, the foam particles are extruded and bonded into a whole plate by using the adhesive in the flame retardant and the pressure formed by secondary foaming to obtain the polystyrene heat-insulating material, and the polystyrene heat-insulating material can be cut and processed into a heat-insulating plate finished product with a specific size. The technical process of the preparation method provided by the invention is shown in figure 1, and figure 1 is a schematic diagram of the preparation process of the polystyrene heat-insulating material provided by the invention.

The preparation method provided by the invention adopts a twice foaming process, the first foaming is carried out before the flame retardant is coated, the second foaming is carried out after the flame retardant is coated, the two times of foaming both adopt a critical fluid intermittent microcellular foaming technology, water vapor is selected as a physical foaming agent to replace a traditional organic foaming agent, and the particles obtained after foaming have uniform cell size, thicker cell wall and higher rebound resilience, higher foaming multiplying power, environmental protection and no pollution.

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

Example 1

S1 preparation of expandable polystyrene particles with negative charges on surface

Raw materials:

preparation:

injecting pure water into a clean reaction kettle, starting stirring, adding an emulsifier (0.5 part), a dispersing agent, a suspending agent and a styrene monomer, then adding an initiator and a plasticizer, heating to 85 ℃, and carrying out heat preservation reaction1 h; thereafter, a quantity of CaCO is added₃Observing the reaction, and adding a certain amount of Ca₃(PO₄)₂And (3) making the pH value to be weakly acidic (the pH value reaches 5-6.5), adding the residual emulsifier (0.5 part) and the anionic monomer, pressing pentane into the reaction kettle by using an air compressor, raising the temperature to 107 ℃, controlling the pressure to be 0.6MPa, reacting for 2 hours, continuing to raise the temperature to 112 ℃, preserving the temperature, reacting for 3.5 hours, and finishing the reaction. And cooling and filtering the product, fully washing the product with deionized water, and drying the product to obtain EPS particles with negative charges on the surface.

S2 flame retardant solution

Raw materials:

firstly, pouring the cationic adhesive and deionized water into a mixer, stirring at the speed of 1000rad/min, then sequentially adding sodium magnesium hydroxide, aluminum hydroxide and expandable graphite, and uniformly stirring to obtain a flame retardant solution.

The cationic adhesive is prepared by the following method: sequentially adding 30 parts of deionized water, 20 parts of waterborne polyurethane, 10 parts of acrylamide and 0.5 part of initiator (azobisisobutyronitrile) into a three-neck flask provided with a thermometer and a stirring rod, and stirring for 20min at 700 r/min; then adding 0.3 part of cross-linking agent (diethanolamine) and 0.5 part of cationic monomer (dimethyl diallyl ammonium chloride), heating to 75 ℃ and reacting for 6 hours; and naturally cooling to 40 ℃ to obtain the cationic adhesive with the polyurethane-acrylamide composite structure.

S3 preparation of polystyrene insulation board

(1) Primary foaming: and (3) placing the EPS particles prepared in the step (S1) into a foaming agent for steam foaming, wherein the conditions are as follows: introducing high-temperature steam of 100 ℃, controlling the pressure to be 0.2MPa, and curing for 1.5 hours to obtain the foamed polystyrene foam.

(2) Coating: adding the polystyrene foam and the flame retardant solution into a stirrer according to the mass ratio of 1: 1, stirring at the rotating speed of 500rad/min for 15min, and then transferring into a dryer to dry at the temperature of 45 ℃ to obtain the polystyrene foam coated with the flame retardant layer.

(3) And (3) secondary foaming: adding the polystyrene foam particles coated with the flame retardant layer obtained in the step (2) into a forming machine for secondary foaming, wherein the conditions are as follows: introducing high-temperature steam of 100 ℃, controlling the pressure to be 0.15MPa, curing for 1h, and drying to obtain the polystyrene insulation board.

The various properties of the obtained polystyrene insulation board were tested, and the results are shown in table 1.

Table 1 properties of polystyrene insulation board obtained in example 1

Item	Standard of merit	Example 1
			Density (kg/m)³)	GB/T 1033.3-2010	65
Thermal conductivity (W/(m.k))	GB/T 10801.2-2002	0.033
			Oxygen index (%)	GB/T2406.93	36
Compressive Strength (KPa)	GB/T 8813-2008	0.331
			Tensile strength (KPa)	GB9641-1988	0.438
Fire rating	GB8624-2006	Grade A2
			Density of smoke	GB8627-2007	8.06
Phenomenon of combustion	GB8624-2006	No melting and dropping, self-extinguishing when away from fire

The results show that the polystyrene insulation board obtained in the embodiment 1 has good flame retardant property, and the oxygen index is up to 36%; the flame-retardant polyurethane foam material has high flame retardance, lower heat conductivity coefficient, high compressive strength and high tensile strength. The appearance of the polystyrene insulation boards obtained in the embodiments 1, 4 and 6 is shown in fig. 2, and fig. 2 is a schematic view of the appearance of the polystyrene insulation boards obtained in the embodiments 1, 4 and 6.

Example 2

Raw materials:

preparation:

injecting pure water into a clean reaction kettle, starting stirring, adding an emulsifier (0.5 part), a dispersing agent, a suspending agent and a styrene monomer, then adding an initiator and a plasticizer, heating to 90 ℃, and carrying out heat preservation reaction for 1 h; thereafter, a quantity of CaCO is added₃Observing the reaction phenomenon, andadding a certain amount of Ca₃(PO₄)₂And (3) leading the pH value to be weakly acidic (the pH value reaches 5-6.5), adding the residual emulsifier (0.5 part) and the anionic monomer, pressing pentane into the reaction kettle by using an air compressor, raising the temperature to 106 ℃, controlling the pressure to be 0.6MPa, reacting for 2 hours, continuing to raise the temperature to 114 ℃, preserving the temperature, reacting for 3.5 hours, and finishing the reaction. And cooling and filtering the product, fully washing the product with deionized water, and drying the product to obtain EPS particles with negative charges on the surface.

S2 flame retardant solution

Raw materials:

firstly, pouring the cationic adhesive and deionized water into a mixer, stirring at the speed of 1000rad/min, then sequentially adding the inorganic nano particles, the aluminum hydroxide and the expandable graphite, and uniformly stirring to obtain a flame retardant solution.

The cationic adhesive is prepared by the following method: adding 35 parts of deionized water, 25 parts of waterborne polyurethane, 13 parts of acrylamide and 0.5 part of initiator (azobisisobutyronitrile) into a three-neck flask provided with a thermometer and a stirring rod in sequence, and stirring for 20min at 700 r/min; then adding 0.3 part of cross-linking agent (diethanolamine) and 0.5 part of cationic monomer (acryloyloxyethyl trimethyl ammonium chloride), heating to 75 ℃ and reacting for 6 hours; and naturally cooling to 40 ℃ to obtain the cationic adhesive with the polyurethane-acrylamide composite structure.

S3 preparation of polystyrene insulation board

(1) Primary foaming: and (3) placing the EPS particles prepared in the step (S1) into a foaming agent for steam foaming, wherein the conditions are as follows: introducing high-temperature steam with the temperature of 96 ℃, controlling the pressure to be 0.4MPa, and curing for 2 hours to obtain the foamed polystyrene foam.

(2) Coating: adding the polystyrene foam and the flame retardant solution into a stirrer according to the mass ratio of 1: 1.5, stirring at the rotating speed of 500rad/min for 20min, and then transferring into a dryer to dry at the temperature of 45 ℃ to obtain the polystyrene foam coated with the flame retardant layer.

(3) And (3) secondary foaming: adding the polystyrene foam particles coated with the flame retardant layer obtained in the step (2) into a forming machine for secondary foaming, wherein the conditions are as follows: introducing high-temperature steam of 110 ℃, controlling the pressure to be 0.1MPa, curing for 1h, and drying to obtain the polystyrene insulation board.

The various properties of the obtained polystyrene insulation board were tested, and the results are shown in table 2.

Table 2 properties of polystyrene insulation board obtained in example 2

The results show that after the inorganic nanoparticles are added, the compression strength of the material is as high as 0.962KPa, the tensile strength is as high as 1.365KPa, the mechanical property of the material is obviously improved, and meanwhile, the material is endowed with better flame retardance and heat preservation.

Example 3

Raw materials:

preparation:

injecting pure water into a clean reaction kettle, starting stirring, adding an emulsifier (0.5 part), a dispersing agent, a suspending agent and a styrene monomer, then adding an initiator and a plasticizer, heating to 80 ℃, and carrying out heat preservation reaction for 1 h; thereafter, a quantity of CaCO is added₃Observing the reaction, and adding a certain amount of Ca₃(PO₄)₂Adjusting pH to weakly acidic (pH 5-6.5), adding the rest emulsifier (0.5 part) and anionic monomer, and adding waterThe pentane is pressed into the reaction kettle by the press, the temperature is raised to 108 ℃, the pressure is controlled to be 0.6MPa, the temperature is continuously raised to 110 ℃ after the reaction is carried out for 2 hours, the temperature is kept for reaction for 3.5 hours, and the reaction is finished. And cooling and filtering the product, fully washing the product with deionized water, and drying the product to obtain EPS particles with negative charges on the surface.

S2 flame retardant solution

Raw materials:

firstly, pouring the cationic adhesive and deionized water into a mixer, stirring at the speed of 1000rad/min, then sequentially adding the inorganic nanoparticles, the magnetic nanoparticles, the aluminum hydroxide and the expandable graphite, and uniformly stirring to obtain a flame retardant solution.

The cationic adhesive is prepared by the following method: adding 40 parts of deionized water, 30 parts of waterborne polyurethane, 20 parts of acrylamide and 0.5 part of initiator (azobisisobutyronitrile) into a three-neck flask provided with a thermometer and a stirring rod in sequence, and stirring for 20min at 700 r/min; then adding 0.5 part of cross-linking agent (diethanolamine) and 0.5 part of cationic monomer (methacryloyloxyethyl trimethyl ammonium chloride), heating to 75 ℃ and reacting for 6 hours; and naturally cooling to 40 ℃ to obtain the cationic adhesive with the polyurethane-acrylamide composite structure.

The magnetic nano particle-quaternary ammonium salt treated layered nano montmorillonite is prepared by the following method:

1 part of nano-layered montmorillonite and 1.5 parts of quaternary ammonium salt (dimethyl diallyl ammonium chloride, molecular weight of 5000) are melted and blended at 50 ℃ to obtain the modified layered nano-montmorillonite.

S3 preparation of polystyrene insulation board

(1) Primary foaming: and (3) placing the EPS particles prepared in the step (S1) into a foaming agent for steam foaming, wherein the conditions are as follows: introducing high-temperature steam of 110 ℃, controlling the pressure to be 0.6MPa, and curing for 1 hour to obtain the foamed polystyrene foam.

(2) Coating: adding the polystyrene foam and the flame retardant solution into a stirrer according to the mass ratio of 1: 1.3, stirring at the rotating speed of 500rad/min for 20min, and then transferring into a dryer to dry at the temperature of 45 ℃ to obtain the polystyrene foam coated with the flame retardant layer.

(3) And (3) secondary foaming: adding the polystyrene foam particles coated with the flame retardant layer obtained in the step (2) into a forming machine for secondary foaming, wherein the conditions are as follows: introducing high-temperature steam with the temperature of 96 ℃, controlling the pressure to be 0.08MPa, curing for 1h, and drying to obtain the polystyrene insulation board.

The various properties of the obtained polystyrene insulation board were tested, and the results are shown in table 3.

Table 3 properties of polystyrene insulation board obtained in example 3

Item	Standard of merit	Example 3
			Density (kg/m)³)	GB/T 1033.3-2010	73
Thermal conductivity (W/(m.k))	GB/T 10801.2-2002	0.030
			Oxygen index (%)	GB/T2406.93	40
Compressive Strength (KPa)	GB/T 8813-2008	1.382
			Tensile strength (KPa)	GB9641-1988	1.743
Fire rating	GB8624-2006	Grade A2
			Density of smoke	GB8627-2007	5.32
Phenomenon of combustion	GB8624-2006	No melting and dropping, self-extinguishing when away from fire

The results show that the polystyrene insulation board obtained in the embodiment 3 has good flame retardant property, and the oxygen index is as high as 40%; the compressive strength is as high as 1.382KPa, and the tensile strength is as high as 1.743 KPa; the magnetic nano particles can generate a positive and negative charge attraction effect with polystyrene foam with a large amount of negative charges on the surface, so that the binding property of the flame retardant and the polystyrene foam is further improved, the flame retardance of the material is improved, and the mechanical property of the material is enhanced.

Example 4

S1 EPS particles

Is a commercial PKF-301XS particle, the particle diameter is 1.0-3.0mm, and the foaming ratio is 40-60 times.

S2 flame retardant solution

Raw materials:

pouring the cationic adhesive and deionized water into a mixer at a stirring speed of 1000rad/min, sequentially adding magnesium hydroxide, aluminum hydroxide and expandable graphite, and uniformly stirring to obtain a flame retardant solution.

The cationic adhesive is prepared by the following method: sequentially adding 30 parts of deionized water, 20 parts of waterborne polyurethane, 20 parts of acrylamide and 0.5 part of initiator (azobisisobutyronitrile) into a three-neck flask provided with a thermometer and a stirring rod, and stirring for 20min at 700 r/min; then adding 0.3 part of cross-linking agent (diethanolamine) and 0.5 part of cationic monomer (methacryloyloxyethyl trimethyl ammonium chloride), heating to 75 ℃ and reacting for 6 hours; and naturally cooling to 40 ℃ to obtain the cationic adhesive with the polyurethane-acrylamide composite structure.

S3 preparation of polystyrene insulation board

(1) Primary foaming: placing commercial EPS particles into a foaming agent for steam foaming, wherein the conditions are as follows: introducing high-temperature steam of 100 ℃, controlling the pressure to be 0.6MPa, and curing for 1.5 hours to obtain the foamed polystyrene foam.

The various properties of the polystyrene insulation board were tested, and the results are shown in table 4.

Table 4 properties of polystyrene insulation board obtained in example 4

Example 5

S1 EPS particles

Is a commercial PKF-401XS particle, the particle diameter is 1.0-3.0mm, and the foaming ratio is 40-60 times.

S2 flame retardant solution

Raw materials:

The cationic adhesive is prepared by the following method: adding 50 parts of deionized water, 30 parts of waterborne polyurethane, 20 parts of acrylamide and 0.5 part of initiator (azobisisobutyronitrile) into a three-neck flask provided with a thermometer and a stirring rod in sequence, and stirring for 20min at 700 r/min; then adding 0.5 part of cross-linking agent (diethanolamine) and 1 part of cationic monomer (methacryloyloxyethyl trimethyl ammonium chloride), heating to 75 ℃ and reacting for 6 hours; and naturally cooling to 40 ℃ to obtain the cationic adhesive with the polyurethane-acrylamide composite structure.

S3 preparation of polystyrene insulation board

(1) Primary foaming: placing commercial EPS particles into a foaming agent for steam foaming, wherein the conditions are as follows: introducing high-temperature steam of 110 ℃, controlling the pressure to be 0.6MPa, and curing for 1 hour to obtain the foamed polystyrene foam.

(2) Coating: adding the polystyrene foam and the flame retardant solution into a stirrer according to the mass ratio of 1: 1, stirring at the rotating speed of 500rad/min for 20min, and then transferring into a dryer to dry at the temperature of 45 ℃ to obtain the polystyrene foam coated with the flame retardant layer.

(3) And (3) secondary foaming: adding the polystyrene foam particles coated with the flame retardant layer obtained in the step (2) into a forming machine for secondary foaming, wherein the conditions are as follows: introducing high-temperature steam of 110 ℃, controlling the pressure to be 0.15MPa, curing for 1h, and drying to obtain the polystyrene insulation board.

The various properties of the obtained polystyrene insulation board were tested, and the results are shown in table 5.

Table 5 properties of polystyrene insulation board obtained in example 5

Item	Standard of merit	Example 5
			Density (kg/m)³)	GB/T 1033.3-2010	64
Thermal conductivity (W/(m.k))	GB/T 10801.2-2002	0.031
			Oxygen index (%)	GB/T2406.93	36
Compressive Strength (KPa)	GB/T 8813-2008	0.618
			Tensile strength (KPa)	GB9641-1988	0.832
Fire rating	GB8624-2006	Grade A2
			Density of smoke	GB8627-2007	11.36
Phenomenon of combustion	GB8624-2006	No melting and dropping, self-extinguishing when away from fire

Example 6

S1 EPS particles

Is a commercial PKF-501XS particle, the particle diameter is 1.0-3.0mm, and the foaming ratio is 40-60 times.

S2 flame retardant solution

Raw materials:

The cationic adhesive is prepared by the following method: adding 50 parts of deionized water, 30 parts of waterborne polyurethane, 20 parts of acrylamide and 0.5 part of initiator (azobisisobutyronitrile) into a three-neck flask provided with a thermometer and a stirring rod in sequence, and stirring for 20min at 700 r/min; then adding 0.5 part of cross-linking agent (diethanolamine) and 2 parts of cationic monomer (methacryloyloxyethyl trimethyl ammonium chloride), heating to 75 ℃ and reacting for 6 hours; and naturally cooling to 40 ℃ to obtain the cationic adhesive with the polyurethane-acrylamide composite structure.

Wherein, the preparation of the magnetic nano particle-quaternary ammonium salt treated layered nano montmorillonite is shown in example 3.

S3 preparation of polystyrene insulation board

(3) And (3) secondary foaming: adding the polystyrene foam particles coated with the flame retardant layer obtained in the step (2) into a forming machine for secondary foaming, wherein the conditions are as follows: introducing high-temperature steam with the temperature of 96 ℃, controlling the pressure to be 0.1MPa, curing for 1 hour, and drying to obtain the polystyrene insulation board.

The various properties of the obtained polystyrene insulation board were tested, and the results are shown in table 6.

Table 6 properties of polystyrene insulation board obtained in example 6

Item	Standard of merit	Example 6
			Density (kg/m)³)	GB/T 1033.3-2010	70
Thermal conductivity (W/(m.k))	GB/T 10801.2-2002	0.035
			Oxygen index (%)	GB/T2406.93	38
Compressive Strength (KPa)	GB/T 8813-2008	1.065
			Tensile strength (KPa)	GB9641-1988	1.243
Fire rating	GB8624-2006	Grade A2
			Density of smoke	GB8627-2007	9.96
Phenomenon of combustion	GB8624-2006	No melting and dropping, self-extinguishing when away from fire

Comparative example 1

S1 EPS particles

S2 flame retardant solution

Raw materials:

25 parts of a commercial flame retardant (Doher-605 available from Dalton chemical industry);

30 parts of adhesive (epoxy resin adhesive EP-1700 purchased from complexing high-tech materials (Shanghai));

and 35 parts of deionized water.

Pouring the adhesive, the flame retardant and the deionized water into a mixer, stirring at a speed of 1000rad/min, and uniformly stirring to obtain a flame retardant solution.

S3 preparation of polystyrene insulation board

The various properties of the resulting polystyrene insulation board were tested and the results are shown in table 7.

Table 7 properties of polystyrene insulation board obtained in comparative example 1

Item	Standard of merit	Example 6
			Density (kg/m)³)	GB/T 1033.3-2010	35
Coefficient of thermal conductivity(W/(m·k))	GB/T 10801.2-2002	0.036
			Oxygen index (%)	GB/T2406.93	34
Compressive Strength (KPa)	GB/T 8813-2008	0.23
			Tensile strength (KPa)	GB9641-1988	0.38
Fire rating	GB8624-2006	Class B
			Density of smoke	GB8627-2007	13.64
Phenomenon of combustion	GB8624-2006	With molten dripping

Comparative example 2

S1 EPS particles

S2 flame retardant

Commercial flame retardant Doher-601, available from Dalton chemical.

S3 preparation of polystyrene insulation board

(1) Adding the commercial EPS particles and the flame retardant into a stirrer according to the mass ratio of 1: 1, stirring at the rotating speed of 500rad/min for 20min, and then transferring into a dryer for drying at the temperature of 45 ℃.

(2) Adding the master batch dried in the step (1) into a forming machine for steam foaming, wherein the conditions are as follows: introducing high-temperature steam of 100 ℃, controlling the pressure to be 0.15MPa, curing for 1h, and drying to obtain the polystyrene insulation board.

The various properties of the resulting polystyrene insulation board were tested and the results are shown in table 8.

TABLE 8 Properties of polystyrene insulation boards obtained in comparative example 2

Item	Standard of merit	Example 6
			Density (kg/m)³)	GB/T 1033.3-2010	28
Thermal conductivity (W/(m.k))	GB/T 10801.2-2002	0.039
			Oxygen index (%)	GB/T2406.93	32
Compressive Strength (KPa)	GB/T 8813-2008	0.15
			Tensile strength (KPa)	GB9641-1988	0.22
Fire rating	GB8624-2006	Class B
			Density of smoke	GB8627-2007	15.06
Phenomenon of combustion	GB8624-2006	With molten dripping

A summary of the properties of examples 1-6 and comparative examples 1-2 is shown in Table 9:

TABLE 9 summary of the properties of the examples and comparative examples

Compared with the comparative examples 1-2, the polystyrene insulation boards obtained in the examples 1-6 of the invention have the advantages of obviously improved oxygen index, improved fire-proof grade and better flame retardance; meanwhile, the compressive strength and the tensile strength are obviously improved; moreover, the heat conductivity coefficient is reduced, and the heat preservation performance is improved; the smoke density is reduced, the environment is protected, and the combustion phenomenon is obviously improved.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polystyrene insulation material, comprising: the flame retardant coating comprises polystyrene foam and a flame retardant layer coated on the surface of the polystyrene foam;

the flame retardant layer comprises the following components in parts by mass:

2. the polystyrene thermal insulation material according to claim 1, wherein the cationic monomer is selected from one or more of dimethyldiallylammonium chloride, acryloyloxyethyltrimethylammonium chloride and methacryloyloxyethyltrimethylammonium chloride.

3. The polystyrene insulation of claim 1 or 2, wherein the cationic adhesive is prepared by:

4. The polystyrene thermal insulation material according to claim 1, wherein the inorganic flame retardant is selected from one or more of magnesium hydroxide, aluminum hydroxide and red phosphorus;

5. The polystyrene thermal insulation material according to claim 1, wherein the positively charged magnetic nanoparticles are selected from one or more of layered nano montmorillonite treated by quaternary ammonium salt, iron-coated modified titanium dioxide, ionic liquid modified carbon nanotubes, graphene oxide and surface cation modified nanocellulose.

6. The polystyrene insulation of claim 1, wherein the polystyrene foam is formed from polystyrene particles;

7. The polystyrene thermal insulation material of claim 6, wherein the EPS particles with negative charges on the surface are prepared by the following method:

8. The polystyrene insulation of claim 7,

in the step S1:

the reaction temperature is 80-90 ℃, and the reaction time is 1-2 h;

in the step S2:

9. A preparation method of the polystyrene heat insulation material as claimed in any one of claims 1 to 8, characterized by comprising the following steps:

10. the production method according to claim 9,

in the step a):

in the step b):

the drying temperature is 25-50 ℃;

in the step c):