阅读说明：本技术 一种聚氨酯泡沫的制备方法 (Preparation method of polyurethane foam ) 是由 胡远洲 董洋 沈保星 黄立祥 于 2020-07-24 设计创作，主要内容包括：本发明提供一种聚氨酯泡沫的制备方法。所述聚氨酯泡沫的制备方法包括以下步骤：(1)将聚醚多元醇、发泡剂、催化剂和泡沫稳定剂混合搅拌,通入气体,并进行保压,得到混合物；(2)将步骤(1)得到的混合物和异氰酸酯混合反应,得到聚氨酯泡沫。所述聚氨酯泡沫的制备方法通过控制溶液中气泡核数量和气泡核的分布,增加气体吸附量,提高气体利用率,同时使气泡均匀分布,从而使制备得到的聚氨酯泡沫泡孔细密、均匀,密度低,且力学性能优良。(The invention provides a preparation method of polyurethane foam. The preparation method of the polyurethane foam comprises the following steps: (1) mixing and stirring polyether polyol, a foaming agent, a catalyst and a foam stabilizer, introducing gas, and maintaining pressure to obtain a mixture; (2) and (2) mixing the mixture obtained in the step (1) with isocyanate for reaction to obtain polyurethane foam. According to the preparation method of the polyurethane foam, the number of bubble nuclei and the distribution of the bubble nuclei in the solution are controlled, so that the gas adsorption quantity is increased, the gas utilization rate is improved, and the bubbles are uniformly distributed, so that the prepared polyurethane foam has fine and uniform bubbles, low density and excellent mechanical property.)

1. A preparation method of polyurethane foam is characterized by comprising the following steps:

(1) mixing and stirring polyether polyol, a foaming agent, a catalyst and a foam stabilizer, introducing gas, and maintaining pressure to obtain a mixture;

(2) and (2) mixing the mixture obtained in the step (1) with isocyanate for reaction to obtain polyurethane foam.

2. The method of preparing polyurethane foam according to claim 1, wherein the mixing and stirring in step (1) is performed at a rotation speed of 90 to 110 r/min.

3. The method for producing a polyurethane foam according to claim 1 or 2, wherein the time for introducing the gas in the step (1) is 200s or more, preferably 280s and 320 s;

preferably, the flow rate of the introduced gas in the step (1) is 300-400L/h, preferably 350L/h;

preferably, the humidity of the gas in step (1) is below 0.05%;

preferably, the gas in step (1) is air.

4. The production method of a polyurethane foam according to any one of claims 1 to 3, characterized in that the pressure of the dwell pressure in step (1) is 1 to 2 bar.

5. The production method of a polyurethane foam as claimed in any one of claims 1 to 4, wherein the mass ratio of the polyether polyol, the blowing agent, the catalyst and the foam stabilizer in the step (1) is (97-99.5): (0.6-1.0): (0.25-0.5): (0.08-0.11);

preferably, the mass ratio of the mixture in the step (1) to the isocyanate in the step (2) is 100 (41-47).

6. The process for preparing a polyurethane foam according to any one of claims 1 to 5, wherein the polyether polyol in step (1) has a functionality of 2 to 4 and a hydroxyl value of 15 to 120mg KOH/g;

preferably, the polyether polyol in step (1) has a number average molecular weight of 2000-.

7. The method of producing a polyurethane foam according to any one of claims 1 to 6, wherein the blowing agent in step (1) is water;

preferably, the catalyst in step (1) is stannous octoate;

preferably, the foam stabilizer in step (1) is silicone oil.

8. The method of producing a polyurethane foam according to any one of claims 1 to 7, wherein the mixture in step (1) further comprises a chain extender;

preferably, the chain extender is triethanolamine;

preferably, the chain extender is added in an amount of 0.18 to 0.25% of the total mass of the mixture.

9. The method of producing a polyurethane foam according to any one of claims 1 to 8, wherein the isocyanate in the step (2) is diphenylmethane diisocyanate;

preferably, the temperature of the mixing reaction in the step (2) is 35-65 ℃, and the time of the mixing reaction is 16-24 h.

10. A process for the preparation of a polyurethane foam as claimed in any one of claims 1 to 9, characterized in that it comprises the following steps:

(1) mixing and stirring polyether polyol, a foaming agent, a catalyst and a foam stabilizer in a mass ratio of (97-99.5): (0.6-1.0): 0.25-0.5): 0.08-0.11) at a rotating speed of 90-110r/min, introducing gas with the humidity of below 0.05% for 300s at a flow rate of 300-400L/h, and maintaining the pressure, wherein the pressure for maintaining the pressure is 1-2bar, so as to obtain a mixture;

(2) mixing the mixture obtained in the step (1) with the mass ratio of 100 (41-47) with isocyanate, and reacting for 16-24h at 35-65 ℃ to obtain the polyurethane foam.

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to a preparation method of polyurethane foam.

Background

The polyurethane foam has the characteristics of high sound absorption coefficient, small density, high elasticity, easiness in processing, simplicity and convenience in construction and the like, and can be used as a filtering material in air conditioning equipment, a ventilation plate in a building, sound insulation equipment or a sound absorption material in the building. In which attention is increasingly paid as a sound absorbing and noise reducing material. However, at present, polyurethane foam products have the problems of coarse and uneven cells, and on one hand, the products have large brittleness, low toughness and poor performance; on the other hand, the product has high density and high material consumption.

Generally, the current methods for foaming polyurethane foams are: stirring and mixing the polyol, the isocyanate and other auxiliary agents by a glue injection machine for reaction to generate CO₂，CO₂Dissolved in solution, CO as the reaction proceeds₂The amount is increased, the solution is in a saturated state, and CO₂The overflow forms initial bubbles, which are dispersed in the solution, and the subsequently generated gas is adsorbed on the surface of the initial bubbles, which are bubble nuclei. Countless bubbles are formed due to continuous generation and expansion of the bubbles, so that the volume and the surface area of a foam system are increased, the thickness of the bubble walls is reduced, the foam system is unstable, the formed bubbles can continue to expand, or the bubbles are combined, or the bubbles collapse and burst, and the foam is stabilized by a foam stabilizer and control of process conditions.

CN104774316A discloses a polyurethane all-water foaming material and a preparation method thereof, wherein the material consists of a material A and a material B; the material A comprises, by mass, 38-53.5% of polyether, 2-5% of an emulsifier, 3-8% of a high-efficiency flame retardant, 1-2% of a foam stabilizer, 0.5-2% of a strongly foaming reactive catalyst and 40-45% of water; the material B comprises 80-90% of polyisocyanate and 10-20% of flame retardant by mass percent, and is prepared by adding the components of the material A into a reaction vessel to be uniformly mixed, adding the material B under stirring, continuously stirring uniformly, pouring the mixed solution into a mould to be foamed after the mixed solution is stirred to be whitish, and adding a strongly foamed reactive catalyst to foam. However, the number of bubble nuclei is too small during foam molding, and the gas adsorption amount is small, resulting in a problem of low gas utilization rate.

CN109575213A provides a dry foaming polyurethane resin, which is prepared from polyalcohol, chain extender, diphenylmethane diisocyanate and N, N-dimethylformamide. The preparation method of the dry foaming polyurethane resin provided by the invention comprises two methods, wherein the one-step method is to directly mix the preparation raw materials for tackifying and diluting, and the dry foaming polyurethane resin can be obtained by controlling the raw material proportion and the viscosity and solid content of the final system; the two-step method is that firstly, diphenylmethane diisocyanate and polyol are prepolymerized to obtain a prepolymer, and then the dry-process foaming polyurethane resin is obtained through chain extension, and the foaming polyurethane resin obtained through dry-process foaming has thick and uneven foam holes, small quantity and poor economic benefit.

Therefore, the development of a polyurethane foam foaming process which increases the number of bubble nuclei and improves the gas utilization rate is the focus of current research in the field.

Disclosure of Invention

In view of the shortcomings of the prior art, the invention aims to provide a preparation method of polyurethane foam. According to the preparation method of the polyurethane foam, the number of the bubble nuclei and the distribution of the bubble nuclei in the solution are controlled, so that the gas adsorption quantity is increased, the gas utilization rate is improved, and the bubbles are uniformly distributed, so that the prepared polyurethane foam has fine and uniform bubbles, low density and excellent performance.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method of preparing a polyurethane foam, comprising the steps of:

(1) mixing and stirring polyether polyol, a foaming agent, a catalyst and a foam stabilizer, introducing gas, and maintaining pressure to obtain a mixture;

(2) and (2) mixing the mixture obtained in the step (1) with isocyanate for reaction to obtain polyurethane foam.

In the invention, polyether polyol, a foaming agent, a catalyst and a foam stabilizer are mixed, gas is introduced into the mixture, and pressure maintaining treatment is carried out on the gas, so that the initial gas is dispersed in the mixture as bubble nuclei, thereby effectively increasing the number of the bubble nuclei; the mixture is stirred to ensure that the cell nuclei are uniformly distributed in the mixture. The preparation method can control the ratio of the total amount of the supersaturated gas to the number of bubble nuclei in the mixture, increase the number of the bubble nuclei, and reduce the number of bubbles obtained by a single bubble nucleus, so that the obtained foam cells are fine and uniform.

Preferably, the mixing and stirring speed in step (1) is 90-110r/min, such as 90r/min, 92r/min, 94r/min, 96r/min, 98r/min, 100r/min, 102r/min, 104r/min, 106r/min, 108r/min, 110 r/min.

The mixing and stirring speed of the invention is 90-110r/min, which is beneficial to the uniform distribution of bubble nuclei in the system, if the speed is too slow, the bubble nuclei can not be uniformly dispersed in the system, and the bubble distribution is nonuniform due to concentration, if the speed is too fast, the material temperature is excessively increased, the reaction speed is accelerated, the fluidity of the material is poor, and the foam density distribution is poor.

Preferably, the time for introducing the gas in the step (1) is more than 200s, for example, 200s, 220s, 240s, 260s, 280s, 300s, 320s, 340s, 380s, 400s, 450s, 500s, etc., preferably 280-320 s.

Preferably, the flow rate of the introduced gas in the step (1) is 300-400L/h, such as 300L/h, 310L/h, 320L/h, 330L/h, 340L/h, 350L/h, 360L/h, 370L/h, 380L/h, 400L/h, and preferably 350L/h.

The invention controls the gas introduction amount by controlling the gas introduction time and flow rate, the initial gases are dispersed in the mixture as bubble nuclei, and finally the number of the bubble nuclei in the solution during foaming is controlled, thereby increasing the gas adsorption amount and improving the gas utilization rate.

Preferably, the humidity of the gas in step (1) is 0.05% or less (sufficiently dry gas is introduced), and may be, for example, 0%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, or the like.

Preferably, the gas in step (1) is air.

Preferably, the pressure of the dwell pressure in step (1) is 1-2bar, and may be, for example, 1bar, 1.1bar, 1.2bar, 1.3bar, 1.4bar, 1.5bar, 1.6bar, 1.7bar, 1.8bar, 1.9bar, 2bar, etc.

In the invention, the number of bubble cores is further ensured to be in a certain range by controlling the pressure of pressure maintaining so as to further ensure that a foam product with fine and uniform foam holes is obtained.

Preferably, the mass ratio of the polyether polyol, the foaming agent, the catalyst and the foam stabilizer in the step (1) is (97-99.5): (0.6-1.0): (0.25-0.5): (0.08-0.11);

wherein "97 to 99.5" may be 97, 97.5, 98, 98.5, 99, 99.5, etc., for example;

wherein "0.6 to 1.0" may be, for example, 0.6, 0.7, 0.8, 0.9, 1.0, etc.;

wherein "0.25 to 0.5" may be, for example, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.;

here, "0.08 to 0.11" may be, for example, 0.08, 0.09, 0.10, 0.11, or the like.

Preferably, the mass ratio of the mixture in the step (1) to the isocyanate in the step (2) is 100 (41-47), and can be 100:41, 100:42, 100:43, 100:44, 100:45, 100:46 and 100: 47.

Preferably, the polyether polyol in step (1) has a functionality of 2 to 4, which may be, for example, 2, 3, 4, and a hydroxyl number of 15 to 120mg KOH/g, which may be, for example, 15mg KOH/g, 20mg KOH/g, 30mg KOH/g, 40mg KOH/g, 50mg KOH/g, 60mg KOH/g, 70mg KOH/g, 80mg KOH/g, 90mg KOH/g, 100mg KOH/g, 110mg KOH/g, 120mg KOH/g, and the like.

Preferably, the polyether polyol in step (1) has a number average molecular weight of 2000-.

Preferably, the blowing agent in step (1) is water.

Preferably, the catalyst in step (1) is stannous octoate.

Preferably, the foam stabilizer in step (1) is silicone oil.

Preferably, the mixture in step (1) further comprises a chain extender.

Preferably, the chain extender is triethanolamine.

Preferably, the chain extender is added in an amount of 0.18 to 0.25% by mass of the total mass of the mixture, and may be, for example, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, etc.

Preferably, the isocyanate in step (2) is diphenylmethane diisocyanate.

Preferably, the temperature of the mixing reaction in the step (2) is 35-65 ℃, for example, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃ and the like, and the time of the mixing reaction is 16-24h, for example, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h and the like.

Preferably, the preparation method of the polyurethane foam comprises the following steps:

(1) mixing and stirring polyether polyol, a foaming agent, a catalyst and a foam stabilizer in a mass ratio of (97-99.5): (0.6-1.0): 0.25-0.5): 0.08-0.11) at a rotating speed of 90-110r/min, introducing gas with the humidity of below 0.05% for 300s at a flow rate of 300-400L/h, and maintaining the pressure, wherein the pressure for maintaining the pressure is 1-2bar, so as to obtain a mixture;

(2) mixing the mixture obtained in the step (1) with the mass ratio of 100 (41-47) with isocyanate, and reacting for 16-24h at 35-65 ℃ to obtain the polyurethane foam.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the preparation method of the polyurethane foam, the number of bubble cores and the distribution of the bubble cores are controlled, so that the gas adsorption quantity is increased, the gas utilization rate is improved, and the bubbles are uniformly distributed, so that the prepared polyurethane foam has fine and uniform cells, low density and excellent performance;

(2) the invention provides polyurethane foams having a foam density of 240-310kg/m³The foam compression strength is 70-110kPa, and the tearing strength is 1.8-2.5 N.mm^-1。

Drawings

FIG. 1 is a sectional view of the polyurethane foam prepared in example 1.

FIG. 2 is a sectional view of the polyurethane foam prepared in example 2.

FIG. 3 is a sectional view of the polyurethane foam prepared in example 3.

FIG. 4 is a sectional view of the polyurethane foam prepared in example 4.

FIG. 5 is a sectional view of the polyurethane foam prepared in example 5.

FIG. 6 is a sectional view of the polyurethane foam prepared in example 6.

FIG. 7 is a sectional view of the polyurethane foam prepared in example 7.

FIG. 8 is a sectional view of the polyurethane foam prepared in example 8.

FIG. 9 is a sectional view of the polyurethane foam prepared in example 9.

FIG. 10 is a sectional view of the polyurethane foam prepared in comparative example 1.

FIG. 11 is a sectional view of the polyurethane foam prepared in comparative example 2.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The sources of the components in the following examples and comparative examples are as follows: polyether polyols were purchased from (manufacturer: hensmei, brand:YO 40067), isocyanates commercially available from (manufacturer: hensmei, brand:3209)。