Flame-retardant polyurethane mixture capable of being mixed at normal temperature for tunnel pavement and preparation method of flame-retardant polyurethane mixture

Abstract

The invention discloses a flame-retardant polyurethane mixture capable of being mixed at normal temperature for tunnel pavement. The flame-retardant polyurethane mixture comprises the following raw materials in parts by weight: 4-12 parts of a polyurethane prepolymer, 0.5-3 parts of a curing agent, 1-3 parts of a reactive diluent, 0.3-2 parts of a hydrolysis-resistant stabilizer, 0.5-3 parts of a special flame retardant and 100 parts of mineral aggregate, the mineral aggregate is composed of aggregate, mineral powder and a photocatalytic material according to the mass ratio of (94-97): (1-5): (1-3). In addition, the invention also discloses a preparation method of the mixture. The polyurethane mixture disclosed by the invention has the characteristics of high strength, good flame retardance, excellent water stability and high and low temperature performance, capability of degrading tail gas and the like, can be mixed, paved and the like under the condition of normal temperature, is particularly suitable for construction in a relatively closed space such as a tunnel, and has a wide application prospect. Due to the excellent flame-retardant property, the safety of driving in the tunnel is greatly improved, and a brand new technical scheme is provided for pavement of a tunnel pavement.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel paving materials, and in particular relates to a flame-retardant polyurethane mixture mixable at room temperature for tunnel paving and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of my country's road transportation industry, the mileage of highways has continued to increase. Many highways under construction and planned to be built inevitably have to pass through deep mountains and valleys, which has led to the continuous breaking of the record of bridge-tunnel ratio, and the number and scale of tunnels have reached unprecedented heights. Pavement is an important part of tunnel construction, and the development of new materials related to tunnel pavement is an important part of improving the quality of highway tunnel construction.

[0003] The traditional tunnel pavement is mainly divided into asphalt concrete pavement and cement concrete pavement, and each of these two pavement forms has its own advantages and disadvantages. The cement concrete pavement has high strength, strong resistance to water damage and can improve the overall brightness of the pavement. However, due to the presence of joints, the smoothness of the cement pavement is affected, the driving comfort is poor, and the anti-skid ability decays quickly, which is not conducive to driving safety. The asphalt concrete pavement is generally paved in the form of a combination of an asphalt mixture upper layer and a concrete lower layer. Asphalt pavement is a flexible pavement that can absorb the vibration generated by the vehicle load, and there is no expansion joint in the asphalt pavement. Compared with the cement concrete pavement, it has the advantages of high flatness, good driving comfort, low noise, and easy maintenance. It is currently the most commonly used tunnel pavement. However, the asphalt concrete pavement is black, which will have a certain impact on the driver's driving vision in the tunnel. In addition, the production process of the asphalt mixture adopts hot mixing technology, and the mixing and compaction temperatures are high, which consumes a lot of energy. A large amount of smoke and harmful gases will be released during the construction process, which has a stronger impact on construction personnel and equipment in a relatively closed space such as a tunnel. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature and a preparation method thereof in view of the deficiencies of the above-mentioned prior art. The polyurethane mixture has the characteristics of high strength, good flame retardancy, excellent water stability and high and low temperature performance, and can degrade tail gas, and can be mixed and spread at room temperature. It is particularly suitable for construction in relatively closed spaces such as tunnels. Its excellent flame retardant properties also greatly improve the safety of driving in tunnels, providing a new technical solution for paving tunnel roads.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A room-temperature mixable flame-retardant polyurethane mixture for tunnel paving, characterized by comprising the following raw materials in parts by weight: 4-12 parts of polyurethane prepolymer, 0.5-3 parts of curing agent, 1-3 parts of active diluent, 0.3-2 parts of hydrolysis-resistant stabilizer, 0.5-3 parts of special flame retardant, and 100 parts of mineral aggregate; the mineral aggregate consists of aggregate, mineral powder, and photocatalytic material in a mass ratio of (94-97):(1-5):(1-3); the special flame retardant is an inorganic-organic composite flame retardant.

[0006] For the above-mentioned room-temperature mixable flame-retardant polyurethane mixture for tunnel paving, it is characterized in that the polyurethane prepolymer is a polyether-type polyurethane prepolymer, with a dynamic viscosity at 25°C less than or equal to 2500 mPa·s, an isocyanate group content range of 2.5% - 5.5%, and an R value [n(-NCO) / n(-OH)] range of 1.2 - 3.

[0007] For the above-mentioned room-temperature mixable flame-retardant polyurethane mixture for tunnel paving, it is characterized in that the curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate mixed in a mass ratio of (5-10):1.

[0008] For the above-mentioned room-temperature mixable flame-retardant polyurethane mixture for tunnel paving, it is characterized in that the active diluent is propylene carbonate or glycidyl alkyl ether, where the alkyl carbon atoms of glycidyl alkyl ether are 12 - 14; the hydrolysis-resistant stabilizer is polycarbodiimide.

[0009] For the above-mentioned room-temperature mixable flame-retardant polyurethane mixture for tunnel paving, it is characterized in that the inorganic flame retardant in the inorganic-organic composite flame retardant is antimony trioxide, and the organic flame retardant is one or more of melamine cyanurate, hexaphenoxycyclotriphosphazene, and triphenyl phosphate, and the mass ratio of the inorganic flame retardant to the organic flame retardant is (1-3):(2-7).

[0010] For the above-mentioned room-temperature mixable flame-retardant polyurethane mixture for tunnel paving, it is characterized in that the preparation method of the inorganic-organic composite flame retardant includes: adding the inorganic flame retardant and the organic flame retardant to a planetary ball mill, grinding at a speed of 300 rpm - 500 rpm for 20 min - 60 min, and then taking out to obtain the inorganic-organic composite flame retardant.

[0011] For the above-mentioned room-temperature mixable flame-retardant polyurethane mixture for tunnel paving, it is characterized in that the aggregate is basalt aggregate, the mineral powder is limestone mineral powder, and the photocatalytic material is anatase-type nano-titanium dioxide.

[0012] The above-mentioned flame-retardant polyurethane mixture for tunnel paving that can be mixed at normal temperature is characterized in that the SiO2 content range of the basalt aggregate is 45% to 50%; the passing mass percentage of the limestone mineral powder through the 0.075mm sieve hole is greater than or equal to 85%, and the plasticity index is less than or equal to 3.5.

[0013] The above-mentioned flame-retardant polyurethane mixture for tunnel paving that can be mixed at normal temperature is characterized in that the grading range of the mineral aggregate is: the passing mass percentage through the 16.0mm sieve hole is 100%, the passing mass percentage through the 13.2mm sieve hole is 90% - 100%, the passing mass percentage through the 9.5mm sieve hole is 65% - 80%, the passing mass percentage through the 4.75mm sieve hole is 35% - 56%, the passing mass percentage through the 2.36mm sieve hole is 22% - 36%, the passing mass percentage through the 1.18mm sieve hole is 12% - 27%, the passing mass percentage through the 0.6mm sieve hole is 8% - 20%, the passing mass percentage through the 0.3mm sieve hole is 5% - 15%, the passing mass percentage through the 0.15mm sieve hole is 3% - 9%, and the passing mass percentage through the 0.075mm sieve hole is 2% - 6%.

[0014] Furthermore, the present invention provides a method for preparing the above-mentioned flame-retardant polyurethane mixture for tunnel paving that can be mixed at normal temperature, which is characterized by including the following steps:

[0015] Step 1: Mix the polyurethane prepolymer, curing agent, and active diluent at normal temperature, and continuously stir at a speed of 200rpm - 300rpm for 10min - 15min to obtain a polyurethane resin binder;

[0016] Step 2: Add the hydrolysis-resistant stabilizer and special flame retardant to the polyurethane resin binder obtained in Step 1, and perform high-speed shearing at a speed of 1000rpm - 3000rpm at normal temperature for 15min - 30min to obtain a flame-retardant polyurethane resin binder;

[0017] Step 3: Under normal temperature conditions, put the aggregate into the mixing pan and stir for 45s - 60s, then add the flame-retardant polyurethane resin binder prepared in Step 2 and continue to stir for 2min - 3min, and finally add the mineral powder and photocatalyst and stir for 2min - 3min to obtain a flame-retardant polyurethane mixture that can be mixed at normal temperature.

[0018] The said parts by weight can be weight measurement units such as grams, liang, jin, kilograms, tons, etc.

[0019] The present invention has the following advantages compared with the prior art:

[0020] 1. The polyurethane mixture of the present invention has the characteristics of high strength, good flame retardancy, excellent water stability, high and low temperature performance, and can degrade exhaust gas. It can be mixed and paved at normal temperature, especially suitable for construction in relatively enclosed spaces such as tunnels. Its excellent flame retardant characteristics also greatly improve the driving safety in tunnels, providing a new technical solution for tunnel pavement paving.

[0021] 2. The present invention uses polyurethane prepolymers, especially polyether-type polyurethane prepolymers, to prepare the mixture. Compared with polyester-type polyurethane, it has stronger water stability. At the same time, the addition of anti-hydrolysis stabilizers further enhances the hydrolysis resistance of polyurethane, making the prepared mixture more suitable for the humid environment of tunnels. At the same time, the durability of polyether-type polyurethane is also better, with stronger stress resistance, and the mixture prepared with it has a longer service life when used for tunnel paving.

[0022] 3. The present invention uses a special flame retardant composed of a compound of organic and inorganic flame retardants to modify the flame retardancy of polyurethane. Its flame retardant effect is more significant than that of single-type inorganic or organic flame retardants. It is preferably to use a planetary ball mill to mix and grind the organic and inorganic flame retardants, so that the composite flame retardant has good compatibility with polyurethane. In addition, the preferred organic flame retardant of the present invention is a halogen-free nitrogen-phosphorus-based or phosphorus-based flame retardant, which will generate non-toxic incombustible gases when burning, dilute oxygen, and at the same time generate free radicals to inhibit the progress of oxidation reactions, and can form a carbonized layer on the polymer surface, thus playing a role in flame retardant protection. This type of flame retardant has the advantages of environmental protection.

[0023] 4. The present invention adds photocatalytic materials to the polyurethane mixture in a way of partially replacing mineral powder. Utilizing the photocatalytic characteristics of the photocatalytic materials, preferably anatase-type nano-titanium dioxide, can efficiently convert gaseous pollutants into harmless compounds such as carbon dioxide, water, nitrates, and sulfates. When used, it can purify the vehicle exhaust in tunnels, with good environmental and economic benefits.

[0024] 5. The flame-retardant polyurethane mixture of the present invention has a certain fluidity at normal temperature, and can adjust the curing speed of polyurethane by adjusting the ratio of polyurethane prepolymer, curing agent, and active diluent to meet the requirements of mixing, transportation, paving, etc. at the construction site, with good construction flexibility. This mixture can be mixed at normal temperature, without special construction equipment, and no large amounts of toxic gases and dust will be generated during the construction process, which is very suitable for tunnel pavement paving.

[0025] The following combines with examples to make a further detailed description of the technical solution of the present invention. Specific Embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0027] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are for illustrative purposes only and do not limit the content of this application.

[0028] In the present invention, the flame-retardant polyurethane mixture that can be mixed at normal temperature is composed of polyurethane prepolymer, curing agent, active diluent, hydrolysis-resistant stabilizer, special flame retardant, and mineral aggregate.

[0029] The polyurethane prepolymer is a polyether-type polyurethane prepolymer with different viscosities, different isocyanate group contents, and different R values; the curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate; the active diluent is propylene carbonate or glycidyl alkyl ether, where the alkyl carbon atoms of glycidyl alkyl ether are 12 - 14; the hydrolysis-resistant stabilizer is polycarbodiimide; the special flame retardant is an inorganic-organic composite flame retardant prepared using a planetary ball mill, where the inorganic flame retardant used is antimony trioxide, and the organic flame retardant is one or several of melamine cyanurate, hexaphenoxycyclotriphosphazene, and triphenyl phosphate; the mineral aggregate is obtained by mixing basalt aggregate, limestone powder, and anatase-type nano-titanium dioxide. All materials used are conventional products that can be obtained through commercial purchase.

[0030] Example 1

[0031] The flame-retardant polyurethane mixture for tunnel paving in this example, which can be mixed at normal temperature, includes the following raw materials in parts by weight: 4 parts of polyurethane prepolymer, 0.5 part of curing agent, 1 part of active diluent, 0.3 part of hydrolysis-resistant stabilizer, 0.5 part of special flame retardant, and 100 parts of mineral aggregate; among them, the mineral aggregate is composed of basalt aggregate, limestone powder, and anatase-type nano-titanium dioxide in a mass ratio of 97:1:2.

[0032] The polyurethane prepolymer is a polyether-type polyurethane prepolymer, with a dynamic viscosity of 1050 mPa·s at 25°C, an isocyanate group content of 2.5%, and an R value [n(-NCO) / n(-OH)] of 1.2.

[0033] The curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate, and the mass ratio of the two is 9:1; the reactive diluent is propylene carbonate; the hydrolysis-resistant stabilizer is polycarbodiimide.

[0034] The special flame retardant is an inorganic-organic composite flame retardant, and its preparation method is: adding antimony trioxide and melamine cyanurate to a planetary ball mill at a mass ratio of 1:2, grinding at a speed of 350 rpm for 30 min and then taking out to obtain the inorganic-organic composite flame retardant.

[0035] The SiO2 content range of the basalt aggregate is 45% - 50%; the passing mass percentage of the limestone powder through a 0.075 mm sieve hole is greater than or equal to 85%, and the plasticity index is less than or equal to 3.5.

[0036] The grading range of the mineral aggregate is: the passing mass percentage through a 16.0 mm sieve hole is 100%, the passing mass percentage through a 13.2 mm sieve hole is 100%, the passing mass percentage through a 9.5 mm sieve hole is 80%, the passing mass percentage through a 4.75 mm sieve hole is 35%, the passing mass percentage through a 2.36 mm sieve hole is 25%, the passing mass percentage through a 1.18 mm sieve hole is 15%, the passing mass percentage through a 0.6 mm sieve hole is 8%, the passing mass percentage through a 0.3 mm sieve hole is 5%, the passing mass percentage through a 0.15 mm sieve hole is 3%, and the passing mass percentage through a 0.075 mm sieve hole is 2%.

[0037] The preparation method of the flame-retardant polyurethane mixture for tunnel paving at normal temperature in this embodiment includes the following steps:

[0038] Step 1: Add methylcyclohexanediamine and dibutyltin dilaurate to a reaction kettle in sequence and stir for 20 min - 30 min at a stirring speed of 300 rpm to obtain the curing agent;

[0039] Step 2: Mix the polyurethane prepolymer, the curing agent and the reactive diluent proportionally at normal temperature and continuously stir at a speed of 200 rpm for 15 min to obtain the polyurethane resin binder;

[0040] Step 3: Add the hydrolysis-resistant stabilizer and the special flame retardant to the polyurethane resin binder obtained in Step 2, and perform high-speed shearing at a speed of 1500 rpm for 20 min at normal temperature to obtain the flame-retardant polyurethane resin binder;

[0041] Step 4: Under normal temperature conditions, put the prepared basalt aggregates of each grade into a mixing pot and stir for 50 s in sequence, then add the flame-retardant polyurethane binder prepared in Step 3 and continue to stir for 3 min, and finally add the limestone powder and anatase-type nano-titanium dioxide and stir for 2 min to obtain the flame-retardant polyurethane mixture that can be mixed at normal temperature.

[0042] Example 2

[0043] The flame-retardant polyurethane mixture for tunnel paving in this example, which can be mixed at normal temperature, comprises the following raw materials in parts by weight: 6 parts of polyurethane prepolymer, 1 part of curing agent, 1.5 parts of active diluent, 0.4 part of hydrolysis-resistant stabilizer, 0.8 part of special flame retardant, and 100 parts of mineral aggregate; wherein, the mineral aggregate is obtained by mixing basalt aggregate, limestone powder and anatase-type nano titanium dioxide in a mass ratio of 94:5:1.

[0044] The polyurethane prepolymer is a polyether-type polyurethane prepolymer, with a dynamic viscosity of 900 mPa·s at 25°C, an isocyanate group content of 2.8%, and an R value [n(-NCO) / n(-OH)] of 1.9.

[0045] The curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate, and the mass ratio of the two is 10:1; the active diluent is propylene carbonate; the hydrolysis-resistant stabilizer is polycarbodiimide.

[0046] The special flame retardant is an inorganic-organic composite flame retardant, and its preparation method is: adding antimony trioxide and hexaphenoxycyclotriphosphazene to a planetary ball mill in a mass ratio of 2:3, grinding at a speed of 300 rpm for 40 min and then taking out to obtain the inorganic-organic composite flame retardant.

[0047] The SiO2 content range of the basalt aggregate is 45% to 50%; the passing mass percentage of the limestone powder through a 0.075 mm sieve hole is greater than or equal to 85%, and the plasticity index is less than or equal to 3.5.

[0048] The grading range of the mineral aggregate is the same as that in Example 1.

[0049] The preparation method of the flame-retardant polyurethane mixture for tunnel paving in this example comprises the following steps:

[0050] Step 1: Add methylcyclohexanediamine and dibutyltin dilaurate to a reaction kettle in sequence and stir for 20 - 30 min at a stirring speed of 300 rpm to obtain a curing agent;

[0051] Step 2: Mix the polyurethane prepolymer, the curing agent and the active diluent at normal temperature in proportion, and continuously stir at a speed of 250 rpm for 15 min to obtain a polyurethane resin binder;

[0052] Step 3: Add the hydrolysis-resistant stabilizer and the special flame retardant to the polyurethane resin binder obtained in Step 2, and perform high-speed shearing at a speed of 2000 rpm at normal temperature for 20 min to obtain a flame-retardant polyurethane resin binder;

[0053] Step 4: Under normal temperature conditions, put the prepared basalt aggregates of each grade into the mixing pot in sequence and stir for 45 s, then add the flame-retardant polyurethane binder prepared in Step 3 and continue stirring for 3 min, and finally add limestone powder and anatase-type nano-titanium dioxide and stir for 2 min to obtain a flame-retardant polyurethane mixture that can be mixed at normal temperature.

[0054] Example 3

[0055] The flame-retardant polyurethane mixture for tunnel paving in this example includes the following raw materials in parts by weight: 8 parts of polyurethane prepolymer, 1.8 parts of curing agent, 2.1 parts of active diluent, 0.9 part of hydrolysis-resistant stabilizer, 1.5 parts of special flame retardant, and 100 parts of mineral aggregate; wherein, the mineral aggregate is obtained by mixing basalt aggregate, limestone powder and anatase-type nano-titanium dioxide in a mass ratio of 94:3:3.

[0056] The polyurethane prepolymer is a polyether-type polyurethane prepolymer, with a dynamic viscosity of 750 mPa·s at 25°C, an isocyanate group content of 3.3%, and an R value [n(-NCO) / n(-OH)] of 2.1.

[0057] The curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate, and the mass ratio of the two is 5:1; the active diluent is glycidyl alkyl ether, wherein the alkyl carbon atom number of the glycidyl alkyl ether is 12-14; the hydrolysis-resistant stabilizer is polycarbodiimide.

[0058] The special flame retardant is an inorganic-organic composite flame retardant, and its preparation method is: adding antimony trioxide and triphenyl phosphate to a planetary ball mill in a mass ratio of 2:5, grinding at a speed of 400 rpm for 40 min and then taking out to obtain the inorganic-organic composite flame retardant.

[0059] The SiO2 content range of the basalt aggregate is 45%-50%; the mass percentage of the limestone powder passing through the 0.075 mm sieve hole is greater than or equal to 85%, and the plasticity index is less than or equal to 3.5.

[0060] The grading range of the mineral aggregate is: the mass percentage passing through the 16.0 mm sieve hole is 100%, the mass percentage passing through the 13.2 mm sieve hole is 95%, the mass percentage passing through the 9.5 mm sieve hole is 75%, the mass percentage passing through the 4.75 mm sieve hole is 56%, the mass percentage passing through the 2.36 mm sieve hole is 36%, the mass percentage passing through the 1.18 mm sieve hole is 27%, the mass percentage passing through the 0.6 mm sieve hole is 20%, the mass percentage passing through the 0.3 mm sieve hole is 15%, the mass percentage passing through the 0.15 mm sieve hole is 9%, and the mass percentage passing through the 0.075 mm sieve hole is 6%.

[0061] The preparation method of the flame-retardant polyurethane mixture for tunnel paving at normal temperature in this embodiment includes the following steps:

[0062] Step 1: Add methylcyclohexanediamine and dibutyltin dilaurate to the reaction kettle in sequence and stir for 20 - 30 min at a stirring speed of 300 rpm to obtain the curing agent.

[0063] Step 2: Mix the polyurethane prepolymer, curing agent, and active diluent at normal temperature in proportion and continuously stir at a speed of 300 rpm for 10 min to obtain the polyurethane resin binder.

[0064] Step 3: Add the hydrolysis-resistant stabilizer and special flame retardant to the polyurethane resin binder obtained in Step 2, and perform high-speed shearing at a rotation speed of 1500 rpm at normal temperature for 30 min to obtain the flame-retardant polyurethane resin binder.

[0065] Step 4: Under normal temperature conditions, put the prepared basalt aggregates of each grade into the mixing pot and stir for 45 s in sequence, then add the flame-retardant polyurethane binder prepared in Step 3 and continue to stir for 3 min. Finally, add limestone powder and anatase-type nano-titanium dioxide and stir for 2 min to obtain the flame-retardant polyurethane mixture that can be mixed at normal temperature.

[0066] Example 4

[0067] The flame-retardant polyurethane mixture for tunnel paving in this embodiment includes the following raw materials in parts by weight: 10 parts of polyurethane prepolymer, 2.6 parts of curing agent, 2.5 parts of active diluent, 1.5 parts of hydrolysis-resistant stabilizer, 2.2 parts of special flame retardant, and 100 parts of mineral aggregate; among them, the mineral aggregate is obtained by mixing basalt aggregate, limestone powder, and anatase-type nano-titanium dioxide in a mass ratio of 94:4.5:1.5.

[0068] The polyurethane prepolymer is a polyether-type polyurethane prepolymer, its dynamic viscosity at 25 °C is 500 mPa·s, the isocyanate group content is 4.3%, and the R value [n(-NCO) / n(-OH)] is 2.3.

[0069] The curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate, and the mass ratio of the two is 9:1; the active diluent is glycidyl alkyl ether, and the alkyl carbon atoms of glycidyl alkyl ether are 12 - 14; the hydrolysis-resistant stabilizer is polycarbodiimide.

[0070] The special flame retardant is an inorganic-organic composite flame retardant, and its preparation method is: add antimony trioxide, melamine cyanurate, and hexaphenoxycyclotriphosphazene to a planetary ball mill in a mass ratio of 2:3:4, grind at a rotation speed of 450 rpm for 50 min and then take out to obtain the inorganic-organic composite flame retardant.

[0071] The gradation range of the mineral aggregate is the same as that in Example 3.

[0072] The preparation method of the flame-retardant polyurethane mixture for tunnel paving in this example, which can be mixed at normal temperature, includes the following steps:

[0073] Step 1: Add methylcyclohexanediamine and dibutyltin dilaurate to the reaction kettle in sequence and stir for 20 - 30 min at a stirring speed of 300 rpm to obtain a curing agent;

[0074] Step 2: Mix the polyurethane prepolymer, curing agent and active diluent proportionally at normal temperature and continuously stir at a speed of 300 rpm for 15 min to obtain a polyurethane resin binder;

[0075] Step 3: Add the hydrolysis-resistant stabilizer and special flame retardant to the polyurethane resin binder obtained in Step 2, and perform high-speed shearing at a rotation speed of 2500 rpm for 20 min at normal temperature to obtain a flame-retardant polyurethane resin binder;

[0076] Step 4: Under normal temperature conditions, put the prepared basalt aggregates of each grade into the mixing kettle and stir for 50 s in sequence, then add the flame-retardant polyurethane binder prepared in Step 3 and continue to stir for 2.5 min, and finally add limestone powder and anatase-type nano-titanium dioxide and stir for 2.5 min to obtain the flame-retardant polyurethane mixture that can be mixed at normal temperature.

[0077] Example 5

[0078] The flame-retardant polyurethane mixture for tunnel paving in this example includes the following raw materials in parts by weight: 10 parts of polyurethane prepolymer, 2.5 parts of curing agent, 2.7 parts of active diluent, 1.3 parts of hydrolysis-resistant stabilizer, 2.2 parts of special flame retardant, and 100 parts of mineral aggregate; among them, the mineral aggregate is obtained by mixing basalt aggregate, limestone powder and anatase-type nano-titanium dioxide in a mass ratio of 96:2.5:1.5.

[0079] The polyurethane prepolymer is a polyether-type polyurethane prepolymer, its dynamic viscosity at 25 °C is 750 mPa·s, the isocyanate group content is 3.3%, and the R value [n(-NCO) / n(-OH)] is 2.1.

[0080] The curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate, and the mass ratio of the two is 9:1; the active diluent is propylene carbonate; the hydrolysis-resistant stabilizer is polycarbodiimide.

[0081] The special flame retardant is an inorganic-organic composite flame retardant, and its preparation method is as follows: Antimony trioxide, hexaphenoxycyclotriphosphazene and triphenyl phosphate are added to a planetary ball mill in a mass ratio of 1:2:3, ground at a speed of 450 rpm for 60 minutes and then taken out to obtain the inorganic-organic composite flame retardant.

[0082] The SiO2 content range of the basalt aggregate is 45% to 50%; the mass percentage of the limestone powder passing through the 0.075 mm sieve hole is greater than or equal to 85%, and the plasticity index is less than or equal to 3.5.

[0083] The gradation range of the mineral aggregate is as follows: the mass percentage passing through the 16.0 mm sieve hole is 100%, the mass percentage passing through the 13.2 mm sieve hole is 90%, the mass percentage passing through the 9.5 mm sieve hole is 65%, the mass percentage passing through the 4.75 mm sieve hole is 50%, the mass percentage passing through the 2.36 mm sieve hole is 22%, the mass percentage passing through the 1.18 mm sieve hole is 12%, the mass percentage passing through the 0.6 mm sieve hole is 9%, the mass percentage passing through the 0.3 mm sieve hole is 6%, the mass percentage passing through the 0.15 mm sieve hole is 4%, and the mass percentage passing through the 0.075 mm sieve hole is 3%.

[0084] The preparation method of the flame retardant polyurethane mixture for tunnel paving at normal temperature in this embodiment includes the following steps:

[0085] Step 1: Add methylcyclohexanediamine and dibutyltin dilaurate to the reaction kettle in sequence and stir for 20 - 30 minutes at a stirring speed of 300 rpm to obtain the curing agent;

[0086] Step 2: Mix the polyurethane prepolymer, curing agent and active diluent in proportion at normal temperature and continuously stir at a speed of 250 rpm for 12 minutes to obtain the polyurethane resin binder;

[0087] Step 3: Add the hydrolysis-resistant stabilizer and the special flame retardant to the polyurethane resin binder obtained in Step 2, and perform high-speed shearing at a speed of 3000 rpm for 15 minutes at normal temperature to obtain the flame retardant polyurethane resin binder;

[0088] Step 4: Under normal temperature conditions, put the prepared basalt aggregates of each grade into the mixing pot and stir for 60 s in sequence, then add the flame retardant polyurethane binder prepared in Step 3 and continue to stir for 2 minutes, and finally add the limestone powder and anatase nano-titanium dioxide and stir for 3 minutes to obtain the flame retardant polyurethane mixture that can be mixed at normal temperature.

[0089] Example 6

[0090] The flame-retardant polyurethane mixture for tunnel paving in this embodiment, which can be mixed at normal temperature, comprises the following raw materials in parts by weight: 12 parts of polyurethane prepolymer, 3 parts of curing agent, 3 parts of active diluent, 2 parts of hydrolysis-resistant stabilizer, 3 parts of special flame retardant, and 100 parts of mineral aggregate; wherein, the mineral aggregate is obtained by mixing basalt aggregate, limestone powder and anatase-type nano-titanium dioxide in a mass ratio of 97:2:1.

[0091] The polyurethane prepolymer is a polyether-type polyurethane prepolymer, with a kinematic viscosity of 400 mPa·s at 25°C, an isocyanate group content of 5.5%, and an R value [n(-NCO) / n(-OH)] of 3.

[0092] The curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate, with a mass ratio of the two being 9:1; the active diluent is glycidyl alkyl ether, wherein the alkyl carbon atoms of the glycidyl alkyl ether are 12 - 14; the hydrolysis-resistant stabilizer is polycarbodiimide.

[0093] The special flame retardant is an inorganic-organic composite flame retardant, and its preparation method is: adding antimony trioxide, melamine cyanurate, hexaphenoxycyclotriphosphazene and triphenyl phosphate to a planetary ball mill in a mass ratio of 3:6:1, grinding at a speed of 500 rpm for 20 min and then taking out to obtain the inorganic-organic composite flame retardant.

[0094] The SiO2 content range of the basalt aggregate is 45% - 50%; the mass percentage of the limestone powder passing through a 0.075 mm sieve hole is greater than or equal to 85%, and the plasticity index is less than or equal to 3.5.

[0095] The grading range of the mineral aggregate is the same as that in Example 5.

[0096] The preparation method of the flame-retardant polyurethane mixture for tunnel paving in this embodiment comprises the following steps:

[0097] Step 1: Add methylcyclohexanediamine and dibutyltin dilaurate to a reaction kettle in sequence and stir for 20 - 30 min at a stirring speed of 300 rpm to obtain the curing agent;

[0098] Step 2: Mix the polyurethane prepolymer, the curing agent and the active diluent proportionally at normal temperature and continuously stir at a speed of 300 rpm for 15 min to obtain the polyurethane resin binder;

[0099] Step 3: Add the hydrolysis-resistant stabilizer and the special flame retardant to the polyurethane resin binder obtained in Step 2, and carry out high-speed shearing at a speed of 1000 rpm for 30 min at normal temperature to obtain the flame-retardant polyurethane resin binder;

[0100] Step 4: At room temperature, put the prepared basalt aggregates of various grades into a mixing pot in turn and stir for 60 seconds, then add the flame-retardant polyurethane binder prepared in step 3 and continue stirring for 3 minutes, finally add limestone powder and anatase nano-titanium dioxide and stir for 2 minutes to obtain a flame-retardant polyurethane mixture that can be mixed at room temperature.

[0101] The present invention measures the tensile strength, elongation at break, surface drying time, actual drying time, oxygen index and smoke density level of the flame retardant polyurethane resin binder prepared in the above six embodiments. The test results all meet the technical requirements of tunnel pavement materials. The relevant data are shown in Table 1:

[0102] Table 1 Performance measurement of flame retardant polyurethane resin binder in various examples

[0103]

[0104]

[0105] The present invention measures the dynamic stability, low temperature bending limit strain, freeze-thaw splitting strength ratio, fatigue performance, Marshall stability and flow value of the flame-retardant polyurethane mixtures mixable at room temperature obtained in the above six embodiments, and compares them with the commonly used SBS modified asphalt mixture. The results are shown in Table 2:

[0106] Table 2 Comparison of road performance of various embodiments and SBS modified asphalt mixture

[0107]

[0108]

[0109] It can be seen from Table 1 and Table 2 that the polyurethane resin binder prepared by the present invention has good flame retardant properties, low smoke density level, high tensile strength and good elongation at break. The high temperature performance, low temperature performance, water stability, fatigue resistance and Marshall strength of the polyurethane mixture prepared therefrom are better than the currently commonly used SBS modified asphalt mixture, and is suitable for use in tunnel pavement.

[0110] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature, characterized in that: The invention comprises the following raw materials in parts by weight: 4 to 12 parts of polyurethane prepolymer, 0.5 to 3 parts of curing agent, 1 to 3 parts of active diluent, 0.3 to 2 parts of anti-hydrolysis stabilizer, 0.5 to 3 parts of special flame retardant and 100 parts of mineral material; the mineral material is composed of aggregate, mineral powder and photocatalytic material in a mass ratio of (94 to 97):(1 to 5):(1 to 3); the special flame retardant is an inorganic-organic composite flame retardant.

2. The flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature according to claim 1, characterized in that: The polyurethane prepolymer is a polyether polyurethane prepolymer, and its 25°C dynamic viscosity is less than or equal to 2500mPa·s, the isocyanate content ranges from 2.5% to 5.5%, and the R value is The range of [n(-NCO) / n(-OH)] is 1.2~3.

3. The flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature according to claim 1, characterized in that: The curing agent is a mixture of methylcyclohexanediamine and dibutyltin dilaurate in a mass ratio of (5-10):

1.

4. The flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature according to claim 1, characterized in that: The active diluent is propylene carbonate or glycidyl alkyl ether, wherein the alkyl carbon number of the glycidyl alkyl ether is 12 to 14; and the anti-hydrolysis stabilizer is polycarbodiimide.

5. The flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature according to claim 1, characterized in that: The inorganic flame retardant in the inorganic-organic composite flame retardant is antimony trioxide, the organic flame retardant is one or more of melamine cyanurate, hexaphenoxy cyclotriphosphazene and triphenyl phosphate, and the mass ratio of the inorganic flame retardant to the organic flame retardant is (1-3):(2-7).

6. The flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature according to claim 5, characterized in that: The preparation method of the inorganic-organic composite flame retardant comprises: adding the inorganic flame retardant and the organic flame retardant into a planetary ball mill, grinding at a rotation speed of 300 rpm to 500 rpm for 20 minutes to 60 minutes, and then taking out to obtain the inorganic-organic composite flame retardant.

7. The flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature according to claim 2, characterized in that: The aggregate is basalt aggregate, the mineral powder is limestone mineral powder, and the photocatalytic material is anatase nano titanium dioxide.

8. The flame-retardant polyurethane mixture for tunnel pavement that can be mixed at room temperature according to claim 7, characterized in that: The SiO2 content of the basalt aggregate is in the range of 45% to 50%; the mass percentage of the limestone powder passing through a 0.075 mm sieve hole is greater than or equal to 85%, and the plasticity index is less than or equal to 3.

5.

9. The flame-retardant polyurethane mixture for tunnel paving that can be mixed at room temperature according to claim 1, characterized in that: The grading range of the mineral material is: the mass percentage passing through the 16.0mm sieve hole is 100%, the mass percentage passing through the 13.2mm sieve hole is 90%-100%, the mass percentage passing through the 9.5mm sieve hole is 65%-80%, the mass percentage passing through the 4.75mm sieve hole is 35%-56%, the mass percentage passing through the 2.36mm sieve hole is 22%-36%, the mass percentage passing through the 1.18mm sieve hole is 12%-27%, the mass percentage passing through the 0.6mm sieve hole is 8%-20%, the mass percentage passing through the 0.3mm sieve hole is 5%-15%, the mass percentage passing through the 0.15mm sieve hole is 3%-9%, and the mass percentage passing through the 0.075mm sieve hole is 2%-6%.

10. A method for preparing a flame-retardant polyurethane mixture for tunnel pavement that can be mixed at room temperature as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Mix the polyurethane prepolymer, curing agent and reactive diluent at room temperature, and stir continuously at a speed of 200 rpm to 300 rpm for 10 min to 15 min to obtain a polyurethane resin binder; Step 2: adding an anti-hydrolysis stabilizer and a special flame retardant to the polyurethane resin binder obtained in step 1, and high-speed shearing at a rotation speed of 1000 rpm to 3000 rpm at room temperature for 15 min to 30 min to obtain a flame-retardant polyurethane resin binder; Step 3: At room temperature, put the aggregate into a mixing pot and stir for 45s to 60s, then add the flame-retardant polyurethane resin binder prepared in step 2 and continue stirring for 2min to 3min, finally add the mineral powder and photocatalyst and stir for 2min to 3min to obtain a flame-retardant polyurethane mixture that can be mixed at room temperature.

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