TWI750732B - Preparation method of heat-resistant polyurethane elastomer - Google Patents

Abstract

The present invention provides a method for preparing an anti-moisture-heat polyurethane elastomer. The steps are as follows: (A) providing a polyol and aliphatic diisocyanate to react under a suitable catalyst and heating environment to generate an isocyanate with an active isocyanate end group. Urethane prepolymer; (B) provide hydroxyl-containing hydrophobic diol and/or castor oil-based triol as chain extender; (C) combine urethane prepolymer and chain extender in The addition reaction is carried out in a suitable heating environment to generate a moisture-heat-resistant polyurethane elastomer material that can be used in a warm and humid environment for a long time.

Description

Preparation method of anti-moisture heat polyurethane elastomer

The present invention relates to a preparation method of a polyurethane elastomer, in particular to a preparation method of a damp-heat-resistant polyurethane elastomer material which can be used in a warm and humid environment for a long time.

Polyurethane (PU) is polymerized from raw materials such as polyol (Polyol), isocyanate (Isocyanate) and chain extender (Chain extender). Polyurethane is a urethane prepolymer (Prepolymer) formed by the polymerization of diisocyanate and polyols or low molecular weight polyols, and then adding chain extenders containing amine groups or hydroxyl functional groups. Chain extension reaction is carried out to form high molecular weight polymers. Polyurethane (PU) contains a structure of soft segment and hard segment at the same time, wherein the crosslink density is high to obtain products that tend to be hard, such as rigid foam. The crosslink density Low to obtain soft and elastic products such as soft foam and soft elastomer. The hard segment acts as a reinforcement to provide multifunctional physical crosslinking, while the soft segment is mobile and exhibits soft and flexible properties, and the hard segment is similar to the cross-linking point. The mobile soft segment is bound and fixed, so that the polyurethane material has very broad physical properties under the interaction of the soft segment and the hard segment. ) chemical structure, it can be called a poly Urethane. The chemical functional group structure representation of polyurethane is shown in the first figure.

Polyurethane polymer materials have been widely used in various livelihood and industrial products, including: runway pavement, floors, shoe materials, sealing and covering materials, adhesives, artificial leather, furniture seats, rollers, etc. It occupies a very important position in daily life. The conventional polyurethane elastomer (Elastomer) is made by mixing all raw materials including: polyol, diisocyanate, and chain extender at the same time, and obtaining polyurethane through heating and hardening reaction. acid ester.

Diisocyanates can be divided into two categories: aromatic diisocyanates and aliphatic diisocyanates. Traditionally, aromatic toluene diisocyanate (TDI, Toluene diisocyanate) is used as the starting isocyanate for urethane prepolymers. Due to the high volatility of toluene diisocyanate , the smell is pungent and carcinogenic and highly toxic, so it is eager to find suitable alternative materials to reduce the health hazards of personnel.

In addition to diisocyanates, another important starting material for the preparation of urethane prepolymers is polyols. Polyols can be divided into polyester polyols and polyether polyols. Polyether polyols have the following advantages: Good hydrolysis resistance, UV resistance and low temperature resistance. Polyester polyols have the disadvantage of being easily hydrolyzed, but have the advantages of good abrasion resistance and oil resistance.

In order to meet the characteristic requirements of polyurethane elastomer materials, urethane prepolymers composed of toluene diisocyanate often need to use chain extenders to extend the urethane prepolymers containing terminal isocyanates (Prepolymer) interacts to form polyurethane elastomer materials. In industry, chloroaniline and 4,4'-methylenebis-dichloroaniline (MOCA, 4,4'-Methylenebis-2-chloroaniline) are often used as chain extenders to crosslink the carbamide composed of toluene diisocyanate by heating. The ester prepolymer produces the final polyurethane elastomer material. However, due to the carcinogenicity of chloroanilinium, the EU sunset clause for chloroanilinium was launched in November 2017, so manufacturers of major elastomer materials urgently need alternative materials. In addition, limited by the nature of polyurethane polymer materials, its heat resistance and moisture resistance properties are still insufficient. If used in a high-humidity environment for a long time, the polyurethane elastomer material is prone to hydrolysis, and the As the time increases, the hydrolysis will become more serious, causing the material to collapse and disintegrate. Therefore, it is increasingly urgent to improve the performance of polyurethane elastomer materials in humid and hot environments.

To sum up, various synthesis methods currently have their own advantages and disadvantages. The applicant of this case hopes to capture the advantages of various synthesis methods through painstaking research, and develop a kind of synthetic method with the advantages of heat resistance and low pollution, which can be used in offshore wind turbine power generation. , underwater connectors, marine sonar components, submarine cables, underwater remote control vehicles and other high-performance water-tight materials and related water-tight components, a method of making an anti-moisture and heat polyurethane elastomer with great market potential .

In view of the above-mentioned shortcomings of the known technology, the main purpose of the present invention is to provide a method for preparing a polyurethane elastomer with anti-moisture heat, by combining high Hydrophobic castor oil-based hydrocarbons, improve the moisture resistance of polyurethane, and branched hydrocarbon molecular configuration to reduce the polarity of diols, improve the prepolymerization of chain extenders and aliphatic carbamates The compatibility of the material improves the overall performance of the polyurethane elastomer material. It has the advantages of heat resistance and low pollution. It is used in offshore wind turbines, underwater connectors, marine sonar components, underwater sensing components, There is great market potential in the application of high-performance watertight materials and related watertight components such as submarine cables and underwater remote control vehicles.

In order to achieve the above object, according to a scheme proposed by the present invention, there is provided a method for producing an anti-moisture-heat polyurethane elastomer, and a method for producing a polyurethane elastomer with an anti-moisture and heat. The steps include: (A) providing a plurality of The polyol and an aliphatic diisocyanate are reacted under a suitable catalyst and a heating environment to generate a urethane prepolymer with an active isocyanate end group; (B) provide a hydroxyl-containing diol and/ Or a castor oil-based triol as a chain extender; (C) carry out an addition reaction with the urethane prepolymer and the chain extender in a suitable heating environment to generate a polyurethane elastomer material .

Preferably, the molecular weight of the urethane prepolymer is between 1500 and 5000.

Preferably, the aliphatic diisocyanate is isophorone diisocyanate.

Preferably, the polyols are selected from aliphatic polyether polyols with a molecular weight of 750-2300.

Preferably, the dihydric alcohols are selected from dihydric alcohols with branched chain hydrocarbon configuration. Alcohols with a molecular weight of 50 to 500.

Preferably, the weight of the castor oil-based triol does not exceed 9% of the total weight of the polyurethane elastomer.

Preferably, the heating environment refers to a temperature range of 80-90°C.

The above overview and the following detailed description and accompanying drawings are all for the purpose of further illustrating the ways, means and effects adopted by the present creation to achieve the predetermined purpose. The other purposes and advantages of the present creation will be explained in the subsequent descriptions and drawings.

S1, S2, S3: Steps

The first figure is a structural diagram of a conventional polyurethane chemical functional group.

The second figure is the reaction pathway diagram of the urethane prepolymer.

The third figure is the reaction pathway diagram of pure polyurethane material.

The fourth figure is the reaction pathway diagram of the polyurethane material containing castor oil.

The fifth figure is a Fourier transform infrared spectrometer (FT-IR) spectral analysis chart of the urethane prepolymer.

The sixth figure is a spectral analysis diagram of a polyurethane Fourier transform infrared spectrometer (FT-IR).

The seventh figure is a thermogravimetric analysis chart of polyurethane.

The eighth figure is a cleavage curve diagram of polyurethane.

The ninth figure is a hardness test chart of polyurethane.

Figure 10 is a flow chart of the manufacturing method of the anti-moisture-heat polyurethane elastomer of the present invention.

The following describes the implementation of the present invention with specific examples, and those skilled in the art can easily understand the advantages and effects of the present invention from the contents disclosed in this specification.

A method for preparing a damp-heat-resistant polyurethane elastomer according to the present invention, please refer to Figure 10, the steps include: Step S1: provide polyol and aliphatic diisocyanate to react under a suitable catalyst and heating environment to generate an active One of the isocyanate end groups, a urethane prepolymer, is used in this embodiment to have excellent hydrolysis resistance. Polyether polyols, which are less prone to cracking and oxidation in high humidity environments, and aliphatic diisocyanates with excellent UV resistance and weather resistance are used as raw materials. Hydroxyl addition reactions produce liquid aliphatic urethane prepolymers containing reactive isocyanate functional groups. In this embodiment, the aliphatic diisocyanate may be isophorone diisocyanate. The polyols may be selected from aliphatic polyether polyols and may have molecular weights ranging from 750 to 2300. In addition, the molecular weight of the urethane prepolymer may be between 1500 and 5000.

Step S2: providing hydroxyl-containing diol and/or castor oil-based triol as a chain extender, in this embodiment, the chain extender may include: branched chain aliphatic diol, or high hydrophobicity of castor oil-based hydrocarbons, while Chain-type aliphatic diols are carbon-branched using non-toxic chloroaniline (none-MOCA), 4,4'-methylenebis-dichloroaniline (MOCA, 4,4'-Methylenebis-2-chloroaniline). The low-polarity hydroxyl hydrocarbons of the chain are used as chain extenders to improve the compatibility of the chain extenders with aliphatic urethane prepolymers, while the castor oil-based hydrocarbons with high hydrophobicity and active hydroxyl groups are used as the chain extenders. Chain extender to further improve the moisture resistance of polyurethane.

In this embodiment, the diol may be selected from diols with branched hydrocarbon configuration, and the molecular weight may be 50 to 500. In addition, the weight of the castor oil-based triol does not exceed 9% of the total weight of the polyurethane elastomer.

Above, the polyurethane is interspersed with soft segments (soft segments) composed of polyols and hard segments (hard segments) composed of isocyanates and chain extenders, and the polarity of the diols is reduced by the branched chain configuration, Improve the compatibility of chain extenders and aliphatic urethane prepolymers, and avoid the regular arrangement and stacking of straight-chain hydrocarbons, resulting in a decrease in the flexibility of the material after long-term use, resulting in the gradual stiffness of the elastomer. The potential disadvantage is to maintain the flexibility of the soft segment, and use the hard segment as a cross-linking point to connect each soft chain block to generate an elastomer material with good physical properties.

Step S3: The urethane prepolymer and the chain extender are subjected to an addition reaction in a suitable heating environment to generate a polyurethane elastomer material. The hydroxyl group of the chain extender reacts fully with the residual diisocyanate of the urethane prepolymer. It is made into a high molecular weight polyurethane elastomer, the shrinkage of the finished product is low, and the moisture and heat resistance of the material is improved.

In this embodiment, the heating environment is in the temperature range of 80-90°C. In the present invention, under the heating environment of 80-90 DEG C, the urethane prepolymer and the chain extender are uniformly mixed and poured into the heated mold, and the isocyanate at the end of the urethane prepolymer and the chain extender are active functional The base undergoes a cross-linking and hardening reaction, thereby fully reacting to generate a high-molecular-weight polyurethane elastomer, and the shrinkage of the finished product is low, which can improve the moisture and heat resistance of the material.

Above, the present invention is different from the traditional one-step process. The polyurethane elastomer (elastomer) is produced by a two-step process. First, an excess of diisocyanate and polyol are used as starting materials to carry out addition polymerization. After the reaction, a urethane prepolymer with regular molecular arrangement is obtained. Then, a cross-linking and hardening reaction is carried out by a chain extender and the residual diisocyanate in the prepolymer to obtain a polyurethane with extremely high molecular weight and good physical properties. Ester elastomer material, high reproducibility between batches and stable quality, the advantages of the two-step process include: low viscosity of liquid prepolymer, easy processing, low heat release of cross-linking reaction, low shrinkage of finished product, solving the conventional one The process method is to mix all raw materials including: polyol, diisocyanate, and chain extender at the same time for hardening reaction. The molecular structure of the product is randomly arranged, the reaction heat is large, the temperature control is not easy, and the diisocyanate monomer is exposed. The amount of material is harmful to human health, the shrinkage rate of hardening is large, and the physical properties of materials between batches vary greatly.

A kind of anti-moisture heat polymerization of the present invention will be described below by way of examples. Preparation of urethane elastomers.

For the preparation method of the urethane prepolymer (Pre-polymer) of the present invention, firstly, 10 g of polypropylene glycol (polypropylene glycol 1000) (PPG for short) is placed in a four-neck separation reaction tank, and the temperature is set to 80° C. Stirrer to stir. Then, 9g of isophorone diisocyanate (IPDI) was slowly dropped into the four-neck separation reaction tank, reacted with polypropylene glycol (PPG1000), and 0.3g of metal catalyst (Dibutyltin dilaurate, DBTDL) was added. ), the temperature is set to 80°C, and the reaction time is 2 hours, that is, the urethane prepolymer is completed. The reaction pathway is shown in the second figure.

For the preparation method of the pure polyurethane CO-PU 0% (without castor oil (CO)) material of the present invention, firstly, 10 g of polypropylene glycol (polypropylene glycol 1000, PPG1000) is placed in a four-necked bottle , then 9g of isophorone diisocyanate (Isophorone diisocyanate, IPDI) is slowly introduced into the bottle, and the metal catalyst (Dibutyltin dilaurate, DBTDL) of 0.3g is added, and a magnetic stirrer is used to stir to make it evenly mixed, The reaction was carried out under the experimental conditions that the time was 2 hours and the temperature was 80 °C. When the aforementioned reaction time was reached, 2.93 g of the chain extender 2-ethylhexane-1,3-diol (2-ethylhexane-1 ,3-diol), continue to react at a temperature of 80 ℃, stir for 0.5 hours, observe whether the viscosity rises and whether the liquid level drops during the experiment, then pour it into a Teflon mold, and put it into a vacuum oven with a temperature of 80 ℃ After 1 day of defoaming, put it into a circulating oven with a temperature of 80 °C for 1 day, that is, take out the finished product and place it After cooling at room temperature, pure polyurethane CO-PU 0% material without castor oil CO can be completed. The reaction pathway is shown in the third figure.

The preparation method of the polyurethane CO-PU 2%, 4%, 6% of the present invention (containing the weight percentage of the castor oil-based trihydric alcohol in the total weight of the polyurethane elastomer) is as follows: 10g of polypropylene glycol (polypropylene glycol 1000, PPG1000) is placed in a four-necked bottle, then 9g of isophorone diisocyanate (Isophorone diisocyanate, IPDI) is slowly introduced into the bottle, and 0.3g of metal catalyst (Dibutyltin dilaurate, DBTDL), stir with a magnetic stirrer to make it evenly mixed, and carry out the reaction under the experimental conditions that the time is 2 hours and the temperature is 80 ° C. When the aforementioned reaction time is reached, slowly drop 2.4g of chain extender 2- Ethylhexane-1,3-diol (2-ethylhexane-1,3-diol), and an appropriate amount of castor oil (Castor oil, CO) as shown in Table 1, react at a temperature of 80 °C, and stir After 0.5 hours, when the viscosity increases significantly, it can be poured into a Teflon mold, put into a vacuum oven with a temperature of 80 °C for deaeration for 1 day, and then placed in a circulating oven with a temperature of 80 °C for 1 day, that is, take out the finished product and place it After cooling at room temperature, the castor oil-containing polyurethane CO-PU 2%, 4%, 6% material can be completed. The reaction pathway is shown in Figure 4.

CO: Castor oil (Castor oil, CO)

The results obtained by the testing procedures illustrating the present invention are provided below.

In the present invention, the polyurethane Fourier transform infrared spectrometer (FT-IR) spectral analysis, polypropylene glycol (polypropylene glycol 1000, PPG) and isophorone diisocyanate (Isophorone diisocyanate, IPDI) react to obtain the carbamate Pre-polymer, it can be seen from the fifth figure that polypropylene glycol (PPG) has obvious -OH hydroxyl groups located at 3600~3500cm ^-1 , and isophorone diisocyanate (IPDI) also has obvious The -NCO isocyanate group peak is located at ^{the position of 2270cm -1} . After a period of time -OH reacts with -NCO, it can be found that the urethane prepolymer (pre-polymer) shows a new peak -NH amine group.

The sixth figure shows the functional group change of urethane prepolymer (pre-polymer) and chain extender diol (diol) and castor oil (castor oil) to form polyurethane (CO-PU), After the -NCO of the urethane prepolymer (pre-polymer) reacts with the -OH of the chain extender, the resulting polyurethane (CO-PU) has no -NCO functional group peak, which proves that the preparation of polyurethane acid ester (CO-PU).

Polyurethane was evaluated by thermogravimetric analysis (TGA) instrument to evaluate the performance of thermal properties of polyurethane with different castor oil (Castor oil, CO) content, as shown by the seventh and eighth figures and Table 2, With the increase of castor oil (CO) content from 0% to 6%, the initial cracking temperature at which the material loses 30% in weight increases from 300°C to 334.7°C, and the maximum cracking temperature (Tmax) also increases from 322°C to 364°C. ℃, and DTG (Derivative thermo-gravimetry) curve cleavage The rate (Rmax) is also retarded from -24 (wt%/min) of pure polyurethane (PU) to -18 (wt%/min) of castor oil-containing polyurethane (CO-PU 6%) ), the overall properties From the cracking curve, it can be clearly observed that the content of castor oil (CO) increases from low to high, and the cracking rate tends to slow down, indicating that the polyurethane containing castor oil (CO-PU) can indeed improve the polyamino Thermal properties of formate esters.

In addition, according to the hardness characteristics of polyurethane, according to ASTM D2240, the hardness test was carried out on the experimental sample with a thickness of 6 mm using a Shore A hardness tester. After the needle was in close contact with the surface of the sample for one second, For the maximum value of the hardness of the sample, continue to repeat the test 5 times at different positions at least 6mm apart according to the previous steps and obtain the average value. As shown in Figure 9, the polyurethane (CO-PU) material is tested for The average hardness was Shore A 79.

Furthermore, in view of the water absorption properties of polyurethane, the polyurethane material will absorb water in water or in a humid environment and increase its weight. This property is called water absorption. The polyurethane water absorption test is carried out according to ASTM D570. The sample is first dried in an oven at 50 °C, then the sample is taken out and weighed, and then the sample is placed in a beaker and soaked in deionized water for 24 hours. Then take it out to remove excess water and weigh it, and use the formula to calculate its water absorption rate. The data in Table 3 shows that, compared with the pure polyurethane material, the castor oil-containing polyurethane (CO-PU6%) has a lower water absorption rate.

Water absorption %=[(weight of absorbed water-weight of dried sample)/weight of dried sample] x 100

To sum up, the preparation method of the anti-moisture heat polyurethane elastomer of the present invention adopts a two-step process, uses excess diisocyanate and polyol as starting materials, and conducts addition polymerization to obtain a regular molecular arrangement. Urethane prepolymer, and then, through the chain extender and the residual diisocyanate in the prepolymer, cross-linking and hardening reaction is carried out to obtain a polyurethane elastomer material with good physical properties, and the material is reproduced between batches High performance, stable quality, low viscosity of liquid prepolymer, easy processing, low heat release of cross-linking reaction, low shrinkage of finished product, and improved heat and humidity resistance of polyurethane elastomer material. The present invention utilizes environmentally friendly low-polarity carbon branched dimethicone by abandoning the toxic chloroaniline (MOCA) chain extender. The alcohol chain extender can improve the compatibility between the chain extender and the aliphatic polymer prepolymer, and use the castor oil-based hydrocarbon with high hydrophobicity and active hydroxyl as the chain extender to further improve the polyurethane The moisture resistance of esters improves the overall performance of the elastomeric material. In the present invention, through the hardening reaction after heating, the hydroxyl group of the chain extender and the residual diisocyanate of the urethane prepolymer are fully reacted to form a high molecular weight polyurethane elastomer, the shrinkage of the finished product is low, and the quality of the material is improved. Moisture and heat resistance. The present invention combines high hydrophobicity castor oil-based hydrocarbons, improves the moisture resistance of polyurethane, and the branched chain hydrocarbon molecular configuration reduces the polarity of dihydric alcohols, improves chain extenders and aliphatic carbamates The compatibility of the ester prepolymer improves the overall performance of the polyurethane elastomer material, and has the advantages of heat and humidity resistance and low pollution. It is used in offshore wind turbines, underwater connectors, marine sonar components, underwater It has great market potential in the application of high-performance watertight materials and related watertight components such as sensing components, submarine cables, and underwater remote control vehicles.

The above-mentioned embodiments are only illustrative of the features and effects of the present creation, and are not intended to limit the scope of the substantial technical content of the present creation. Anyone skilled in the art can modify and change the above-mentioned embodiments without departing from the spirit and scope of creation. Therefore, the protection scope of the rights of this creation should be listed in the patent application scope described later.

S1, S2, S3: Steps

Claims (5)

A preparation method of an anti-moisture-heat polyurethane elastomer, the steps comprising: (A) providing a polyol and an aliphatic diisocyanate to react under a suitable catalyst and a heating environment to generate one with an active isocyanate end group A urethane prepolymer; (B) providing a hydroxyl-containing diol and a castor oil-based triol as a chain extender; (C) the urethane prepolymer and the chain extension The addition reaction of the agent is carried out in a suitable heating environment to generate a polyurethane elastomer material, wherein the hydroxyl-containing diol is 2-ethylhexane-1,3-diol, wherein , the weight of the castor oil-based triol is 6% of the total weight of the polyurethane elastomer. According to the method for producing the anti-moisture heat polyurethane elastomer described in item 1 of the patent application scope, the molecular weight of the urethane prepolymer is between 1500 and 5000. The method for producing a damp-heat-resistant polyurethane elastomer as described in the first item of the patent application scope, wherein the aliphatic diisocyanate is isophorone diisocyanate. The method for producing a moisture-heat-resistant polyurethane elastomer as described in the first item of the patent application scope, wherein the polyol is selected from aliphatic polyether polyols, and the molecular weight is 750-2300. The method for producing an anti-moisture heat polyurethane elastomer as described in item 1 of the claimed scope, wherein the heating environment refers to a temperature range of 80-90°C.

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