阅读说明：本技术 一种高密度高导热系数聚氨酯泡棉及其制备方法 (High-density high-thermal conductivity polyurethane foam and preparation method thereof ) 是由 唐勇军 于 2020-08-04 设计创作，主要内容包括：本发明提供一种高密度高导热系数聚氨酯泡棉及其制备方法。所述制备方法包括以下步骤：步骤一、将纯化的单壁碳纳米管和大孔分子筛混合均匀；步骤二、将多元醇、扩链剂、水加入到反应釜中,搅拌均匀后,将所述反应釜升温至50～62℃,然后将步骤一得到的纯化单壁碳纳米管和大孔分子筛加入到反应釜中,并搅拌直至分散均匀；步骤三、将反应釜降至常温,再依次将催化剂、加入到反应釜中混合均匀；步骤四、称取重量份数为100份的二苯甲烷二异氰酸酯加入到反应釜中,搅拌5～10min得到预聚体；步骤五、将所述预聚体加入到超声微波协同萃取设备中进行反应得到高密度高导热系数聚氨酯泡棉。采用本发明的方法制备的聚氨酯泡棉具有高密度和高导热性。(The invention provides high-density high-thermal conductivity polyurethane foam and a preparation method thereof. The preparation method comprises the following steps: step one, mixing the purified single-walled carbon nanotube and the large-pore molecular sieve uniformly; adding polyol, a chain extender and water into a reaction kettle, uniformly stirring, heating the reaction kettle to 50-62 ℃, adding the purified single-walled carbon nanotube and the large-pore molecular sieve obtained in the step one into the reaction kettle, and stirring until the single-walled carbon nanotube and the large-pore molecular sieve are uniformly dispersed; step three, cooling the reaction kettle to normal temperature, and then sequentially adding the catalyst and the catalyst into the reaction kettle to be uniformly mixed; step four, weighing 100 parts by weight of diphenylmethane diisocyanate, adding into the reaction kettle, and stirring for 5-10 min to obtain a prepolymer; and step five, adding the prepolymer into ultrasonic microwave synergistic extraction equipment for reaction to obtain the high-density high-thermal conductivity polyurethane foam. The polyurethane foam prepared by the method has high density and high thermal conductivity.)

1. A preparation method of high-density high-thermal conductivity polyurethane foam is characterized by comprising the following steps:

step one, adding 22-40 parts of purified single-walled carbon nanotubes obtained by pretreatment and 10-20 parts of large-pore molecular sieve into a three-dimensional mixer for fully mixing until 40% -50% of the purified single-walled carbon nanotubes are positioned in the large-pore molecular sieve;

step two, adding 50-80 parts of polyol, 4-7 parts of chain extender and 3-8 parts of water into a reaction kettle, uniformly stirring at normal temperature, heating the reaction kettle to 50-62 ℃, adding the purified single-walled carbon nanotube and the large-pore molecular sieve obtained in the step one into the reaction kettle, and stirring at a first stirring speed for 1-2 hours until the single-walled carbon nanotube and the large-pore molecular sieve are uniformly dispersed;

step three, cooling the reaction kettle to normal temperature, sequentially adding 1-3 parts of catalyst and 2-5 parts of foam stabilizer into the reaction kettle, and uniformly mixing at a second stirring speed;

step four, cooling the reaction kettle to 1-3 ℃ under the stirring state, then weighing 100 parts by weight of diphenylmethane diisocyanate, adding the diphenylmethane diisocyanate into the reaction kettle, and stirring at a third stirring speed for 5-10 min to obtain a prepolymer;

and step five, adding the prepolymer obtained in the step four into ultrasonic microwave synergistic extraction equipment for reaction to obtain the high-density high-thermal conductivity polyurethane foam, wherein the reaction is divided into two stages, the ultrasonic microwave reaction time is set to be 0.5-1 h in the first stage, the ultrasonic microwave reaction temperature is 1-3 ℃, the ultrasonic output power is 700-900W, the ultrasonic microwave reaction time is set to be 13-20 min in the second stage, the ultrasonic microwave reaction temperature is 40-50 ℃, and the ultrasonic output power is 80-120W.

2. The method for preparing high-density high-thermal conductivity polyurethane foam according to claim 1, wherein the weight ratio of the purified single-walled carbon nanotubes to the large-pore molecular sieve is (1.3-2.5): 1.

3. the preparation method of the polyurethane foam with high density and high thermal conductivity according to claim 1, wherein the step one of pretreating to obtain the purified single-walled carbon nanotube comprises mixing 100 parts of single-walled carbon nanotube and 200-250 parts of dimethylformamide, performing ultrasonic dispersion for 1.5-2.5 h at an ultrasonic power of 800W, and drying to obtain the purified single-walled carbon nanotube.

4. The method of claim 3, wherein the single-walled carbon nanotubes are hydroxyl-functionalized carbon nanotubes.

5. The method for preparing the polyurethane foam with high density and high thermal conductivity according to claim 1, wherein the polyol comprises polyol 1 and polyol 2, and the weight ratio of the polyol 1 to the polyol 2 is 1 (0.6-1); wherein the polyol 1 is polyvinyl alcohol with the average molecular weight of 8-13 ten thousand and the pH value of 5.5-6.8; the polyol 2 is prepared by ring-opening polymerization of a mixture of sucrose, sorbitol and glycerol and oleic acid serving as an initiator and propylene oxide serving as a polymerization monomer, and the hydroxyl value is 520-640 mgKOH/g.

6. The method for preparing high-density high-thermal-conductivity polyurethane foam according to any one of claims 1 to 5, wherein the first stirring speed is 1500 to 1800r/min, the second stirring speed is 900 to 1200r/min, and the third stirring speed is 2000 to 2200 r/min.

7. The method for preparing high-density high-thermal-conductivity polyurethane foam according to claim 1, wherein the catalyst is a mixture of amine catalyst diethanolamine and tin catalyst dibutyltin dilaurate, and the weight ratio of the diethanolamine to the dibutyltin dilaurate is (0.2-0.4): 1.

8. the method for preparing the polyurethane foam with high density and high thermal conductivity according to claim 1, wherein the chain extender is one or more of ethylene glycol, 1, 4-butanediol and glycerol.

9. The method as claimed in claim 1, wherein the foam stabilizer is polydimethylsiloxane.

10. A high-density high-thermal conductivity polyurethane foam, which is prepared by the preparation method of the high-density electric conduction polyurethane foam as claimed in any one of claims 1 to 9.

Technical Field

The invention relates to a polyurethane foam product, in particular to high-density high-thermal conductivity polyurethane foam and a preparation method thereof.

Background

The polyurethane foam material is an organic polymer material which is obtained by reacting polyisocyanate and polyol and contains a plurality of urethane chain segments. The polyurethane material has excellent mechanical, acoustic, electrical and chemical medium resistance, wide hardness range, good flexibility, bonding performance, wear resistance, low temperature resistance, radiation resistance and the like. The polyurethane material is widely applied in the fields of automobiles, machinery, electronics, packaging, buildings, medical treatment, aerospace and the like.

As is well known, along with the development of scientific technology, the variety of electronic components is increasing, and the connection of circuits tends to be fine and dense, so that great requirements are made on the connection stability of each component of an electronic device. Polyurethane foam tapes are often used for connection among electronic devices in electronic equipment such as mobile phones, and if the heat conductivity is poor, the effective functions of the electronic devices can be influenced, and even when the electronic devices work in an overload state, electronic components can be damaged due to overhigh temperature.

In addition, the polyurethane foam tapes used in electronic components also need to have sufficient density to ensure compression resistance and durable stability in long-term use.

Therefore, in order to meet the application of the polyurethane foam material in various different scenes, it is necessary to develop a polyurethane foam material with high density and good heat-conducting property.

Disclosure of Invention

According to the invention, the polyurethane foam with high density and good heat conductivity is provided, so that the prepared polyurethane foam product has better shock absorption performance, buffering performance and performance, and the requirement of updating and upgrading electronic products can be met.

The embodiment of the invention provides a preparation method of high-density high-thermal conductivity polyurethane foam, which comprises the following steps:

step one, adding 22-40 parts of purified single-walled carbon nanotubes obtained by pretreatment and 10-20 parts of large-pore molecular sieve into a three-dimensional mixer for fully mixing until 40% -50% of the purified single-walled carbon nanotubes are positioned in the large-pore molecular sieve;

step two, adding 50-80 parts of polyol, 4-7 parts of chain extender and 3-8 parts of water into a reaction kettle, uniformly stirring at normal temperature, heating the reaction kettle to 50-62 ℃, adding the purified single-walled carbon nanotube and the large-pore molecular sieve obtained in the step one into the reaction kettle, and stirring at a first stirring speed for 1-2 hours until the single-walled carbon nanotube and the large-pore molecular sieve are uniformly dispersed;

step three, cooling the reaction kettle to normal temperature, sequentially adding 1-3 parts of catalyst and 2-5 parts of foam stabilizer into the reaction kettle, and uniformly mixing at a second stirring speed;

step four, cooling the reaction kettle to 1-3 ℃ under the stirring state, then weighing 100 parts by weight of diphenylmethane diisocyanate, adding the diphenylmethane diisocyanate into the reaction kettle, and stirring at a third stirring speed for 5-10 min to obtain a prepolymer;

and step five, adding the prepolymer obtained in the step four into ultrasonic microwave synergistic extraction equipment for reaction to obtain the high-density high-thermal conductivity polyurethane foam, wherein the reaction is divided into two stages, the ultrasonic microwave reaction time is set to be 0.5-1 h in the first stage, the ultrasonic microwave reaction temperature is 1-3 ℃, the ultrasonic output power is 700-900W, the ultrasonic microwave reaction time is set to be 13-20 min in the second stage, the ultrasonic microwave reaction temperature is 40-50 ℃, and the ultrasonic output power is 80-120W.

The single-walled carbon nanotube has larger length-diameter ratio, larger specific surface and stronger mechanical property, and can enhance the conductivity of the polymeric composite material. However, the inner diameter of the single-walled carbon nanotube is small, and the structure of the single-walled carbon nanotube has certain dispersibility, so that the single-walled carbon nanotube cannot be fully dispersed and filled into the foam pores of polyurethane foam, and cannot completely and effectively support the foam pore structure. In order to further improve the strength and the heat conductivity of the polyurethane foam, a certain amount of macroporous molecular sieve material is added. The macroporous molecular sieve material has extremely high specific surface area and a regular and ordered pore structure, the pore diameter of the macroporous molecular sieve material can generally reach hundreds of nanometers, and the macroporous molecular sieve material has very high mechanical strength and good heat conductivity.

The invention disperses the single-walled carbon nano-tube and the large-pore molecular sieve in the closed foam pores of the foam, and the single-walled carbon nano-tube and the large-pore molecular sieve can be mutually nested and contacted, thereby reducing the aperture ratio of polyurethane foam, increasing the contact area of the polyurethane foam and improving the heat conductivity coefficient of the polyurethane foam. In addition, the materials have higher density, can further enhance the density and have better strength. Can achieve the double effects of high heat conductivity coefficient and high density at the same time.

Further, the weight ratio of the purified single-walled carbon nanotube to the large-pore molecular sieve is (1.3-2.5): 1.

by further limiting the weight ratio of the single-walled carbon nanotube to the large-pore molecular sieve, on one hand, enough single-walled carbon nanotubes need to be ensured to form a stable structure with the large-pore molecular sieve, so that the heat conductivity is good, and on the other hand, the single-walled carbon nanotubes which do not enter the large-pore molecular sieve can be inserted between the large-pore molecular sieve, so that the agglomeration is effectively prevented. Of course, if the single-walled carbon nanotubes are not uniformly dispersed when being added in excess, aggregation can occur, which leads to stress concentration at the aggregated part and reduces the index of the prepared polyurethane foam.

In the embodiment, the diameter of the single-walled carbon nanotube is 0.4-1 nm.

Further, the method for obtaining the purified single-walled carbon nanotube by the pretreatment in the first step comprises the steps of mixing 100 parts of the single-walled carbon nanotube with 200-250 parts of dimethylformamide, performing ultrasonic dispersion for 1.5-2.5 hours at the ultrasonic power of 800W, and drying to obtain the purified single-walled carbon nanotube.

The prepared single-walled carbon nanotubes mostly include impurities such as catalyst metal particles, amorphous carbon and graphite particles, which affect the dispersibility of the single-walled carbon nanotubes in the polyol polymer, and thus, in this embodiment, purified single-walled carbon nanotubes are used.

Further, the single-walled carbon nanotube is a hydroxyl-functionalized carbon nanotube.

Further, the polyol comprises polyol 1 and polyol 2, and the weight ratio of the polyol 1 to the polyol 2 is 1 (0.6-1); wherein the polyol 1 is polyvinyl alcohol with the average molecular weight of 8-13 ten thousand and the pH value of 5.5-6.8; the polyol 2 is prepared by ring-opening polymerization of a mixture of sucrose, sorbitol and glycerol and oleic acid serving as an initiator and propylene oxide serving as a polymerization monomer, and the hydroxyl value is 520-640 mgKOH/g.

The single-walled carbon nanotube has better dispersion performance in polyvinyl alcohol, the polyol 2 has higher hydroxyl value, and the high-density polyurethane foam can be obtained by the reaction with diphenylmethane diisocyanate.

Further, the first stirring speed is 1500-1800 r/min, the second stirring speed is 900-1200 r/min, and the third stirring speed is 2000-2200 r/min.

Further, the catalyst is a mixture of amine catalyst diethanolamine and tin catalyst dibutyltin dilaurate, and the weight ratio of the diethanolamine to the dibutyltin dilaurate is (0.2-0.4): 1.

the invention limits the weight ratio of the diethanol amine to the dibutyltin dilaurate so as to enable the gelation rate and the foaming rate to reach a balance value, and the foam has stable size and good smoothness.

Further, the chain extender is one or more of ethylene glycol, 1, 4-butanediol and glycerol.

The chain extenders have 2 hydrogen atoms which are reactive toward isocyanates and can be used individually or in the form of mixtures.

Further, the foam stabilizer is polydimethylsiloxane.

The polydimethylsiloxane can stabilize the foam performance, can also improve the extensibility of polyurethane foam, and is also synergistic in flame retardance.

The embodiment of the invention also provides the high-density high-thermal conductivity polyurethane foam prepared by the preparation method of the high-density conductive polyurethane foam

The invention has the following beneficial effects:

firstly, the single-walled carbon nanotube and the large-pore molecular sieve are added into the raw materials for preparing the polyurethane foam, so that the single-walled carbon nanotube and the large-pore molecular sieve can enter the closed cells of the foam to occupy a certain pore space, and the amount of foaming agent gas in the closed cells is reduced, so that the polyurethane foam has higher heat-conducting property. Because the large pore molecular sieve and the single-wall carbon nano tube are uniformly mixed, the single-wall carbon nano tube can preferentially enter the inside of the large pore molecular sieve, the density and the mechanical strength of the large pore molecular sieve are increased, and the heat conductivity of the large pore molecular sieve is improved. The macroporous molecular sieve is fully contacted with the closed foam pores, and plays a good role in structural support and heat transfer. And the single-walled carbon nano-tube in the large-pore molecular sieve has excellent heat-conducting property, so that the good heat-conducting property of the polyurethane foam is ensured to a certain extent. And the innermost single-walled carbon nanotube has excellent heat-conducting property, so that the polyurethane foam has excellent heat-conducting property from inside to outside. The structural stability and strength of the single-walled carbon nanotube and the large-pore molecular sieve per se ensure that the polyurethane foam has enough strength and stability to a certain extent. Thereby finally achieving the double effects of high heat conductivity coefficient and high density.

Secondly, putting a prepolymer obtained by uniformly mixing the material A and the material B into ultrasonic microwave synergistic extraction equipment to perform ultrasonic-microwave multiple circulation to prepare polyurethane cotton, wherein the ultrasonic microwave reaction is provided with two stages, and the first stage aims to ensure that the single-walled carbon nanotube and the large-pore molecular sieve can be uniformly dispersed in the prepolymer through ultrasonic dispersion; the second stage aims at increasing the closed cell rate of the foam and improving the density of the polyurethane foam by the mechanical disturbance and cavitation of the ultrasonic waves; on the other hand, the specific thermal effect and the non-thermal effect of the microwave field are combined together, so that the reaction is more sufficient, the reaction activation energy is reduced, and the reaction temperature can be further reduced; and the microwave field heating can rapidly and uniformly heat molecules directly to promote the chemical reaction, so that the single-walled carbon rice tubes and the large-pore molecular sieve can be uniformly distributed in the inner part and the edge part of the polyurethane foam simultaneously, and the density and the heat conductivity of the polyurethane foam are improved.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention is further described below with reference to specific embodiments.