CN1807478A - Polyurethane prepolymer interface coupling agent and its preparation method and uses - Google Patents

Abstract

A polyurethane prepolymer interface coupling agent and its preparation method and application belong to the technical field of chemical interface coupling agents. The number-average molecular weight of the coupling agent is 3000-10000, the dispersion index is 1.6-2.8, and the glass transition temperature is -80-20°C measured by differential scanning calorimetry. The blending ratio is 2:1-20:1, and it is prepared by heating at 60-150°C. Utilizing the coupling agent synthesized by the present invention to pretreat agricultural residue fibers and thermoplastics by blending at room temperature can significantly improve the compatibility and interfacial bonding strength of the agricultural residue fiber/thermoplastic composite interface, and effectively improve the Physical and mechanical properties of composite materials.

Description

A kind of polyurethane prepolymer interfacial coupling agent and its preparation method and application

technical field

The invention relates to a polyurethane prepolymer (hereinafter referred to as polyurethane) interface coupling agent and its preparation method and application, in particular to an interface coupling agent applied to agricultural residue fibers and thermoplastic composite materials.

Background technique

Among the four major materials (steel, cement, wood, plastic) in the world today, wood is the only natural composite biopolymer resource that is renewable, most environmentally friendly, plays an important role in ecological balance, and is easy to recycle and recycle. In the 21st century, when my country's economic construction is developing steadily and people's living standards are constantly improving, the construction industry, manufacturing industry, furniture industry, interior decoration industry, packaging industry and the future wooden house construction industry have a great impact on wood and wood products. The demand for quantity and quality is growing day by day.

However, the supply of timber resources in my country is insufficient, especially the implementation of natural forest protection projects, and the gap between supply and demand of timber is increasing day by day.

my country is a large agricultural country with rich fiber resources of agricultural residues. For example, in 1998, food crops (including rice, wheat, corn, millet, etc.), oil crops (including peanuts, rapeseed, flax, sesame, etc.), cotton, hemp ( The total resources of jute kenaf, ramie, hemp, flax, etc.) and sugar crops (mainly including sugarcane and sugar beet) have reached 1.28 billion tons. Similar to the main components of wood, agricultural residue fibers are also composed of cellulose, hemicellulose and lignin macromolecular polymers. In addition, with the gradual development of the plastics processing industry into a pillar industry of the national economy with a wide variety and complete categories, the consumption of thermoplastics: low-density or high-density polyethylene, polypropylene, polyvinyl chloride, polystyrene, etc. is increasing year by year , waste is also increasing year by year. The characteristics of plastic polymer structure determine its stable physical and chemical properties, large unit mass volume, aging resistance, corrosion resistance, and difficult to be biodegraded. Therefore, a large amount of waste plastic film, plastic The "white pollution" produced by bags and other light-colored plastic wastes has become one of the main sources of environmental pollution.

Therefore, a new type of high-quality agricultural residue fiber/thermoplastic composite material formed by compounding agricultural residue fibers and recycled thermoplastics according to a certain process is an important way to actively expand the raw material resources of the wood industry and develop new wood substitutes. It is one of the important technical measures to alleviate the shortage of wood resources, improve the ecological environment, and solve the contradiction between supply and demand. It meets the requirements of sustainable development of my country's economy and forestry, and is one of the important research directions in the field of wood science and technology.

However, the cellulose, hemicellulose, and lignin contained in agricultural residue fibers are hydrophilic polymers, and thermoplastics are composed of non-polar or weakly polar hydrophobic polymers. Agricultural residue fibers and thermoplastics Compounding, although a macroscopically uniform blending system is obtained by relying on polymer hot melting, the interface compatibility is poor. Therefore, only agricultural surplus fibers are compounded with thermoplastics, and the interface bonding of the composite material is weak. , the weak bond at the interface of the composite material becomes the first damaged area in the process of stress transfer, and the physical and mechanical properties of the composite material are poor.

Contents of the invention

One of the technical tasks of the present invention is to provide a novel polyurethane interfacial coupling agent in order to make up for the deficiencies of the prior art.

The second technical task of the present invention is to provide a preparation method of this interface coupling agent.

The third technical task of the present invention is to provide the application of the coupling agent.

Technical scheme of the present invention is as follows:

1. Polyurethane interface coupling agent

Polyurethane interfacial coupling agent of the present invention, number-average molecular weight is 3000～10000, dispersion index is 1.6～2.8, glass transition temperature (Tg) is measured as-80～20 ℃ by differential scanning calorimetry (DSC), is that It is prepared by blending isocyanate and polyol according to the molar ratio of free isocyanate group (NCO) and hydroxyl group (OH) in the range of 2:1 to 20:1, and heating at 60 to 150°C.

Two, the preparation method of polyurethane interfacial coupling agent

The preparation method of polyurethane interfacial coupling agent, the steps are as follows:

Blend isocyanate and polyol according to the molar ratio of free isocyanate group (NCO) and hydroxyl group (OH) at 2:1-20:1, heat at 60-150°C for 60-240 minutes, and periodically take the reaction Carry out chemical titration or infrared spectrum detection until the percentage of isocyanate group (NCO%) is constant, cool, and discharge to obtain the product polyurethane interfacial coupling agent.

The above-mentioned isocyanate refers to an aromatic or aliphatic compound containing free isocyanate groups with a molecular weight of 100-500, specifically selected from one or a combination of the following: toluene diisocyanate (TDI), modified TDI and TDI trimer, Diphenylmethane diisocyanate (MDI), liquefied MDI, polyphenylpolymethylene polyisocyanate (PAPI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclo Hexamethylene diisocyanate, or water-emulsifiable MDI or PAPI.

The above-mentioned polyol refers to a mixture of polyol polymers having a molecular weight of 300-8000.

The polyol polymer is a polymer of polyether polyol, or a mixture of a polymer of polyether polyol and a polymer of polyester polyol, and the functionality of polyether polyol polymer and polyester polyol polymer both 2 or 3;

The polyether polyol is selected from polyoxypropylene ether polyol, polyoxyethylene ether polyol, polytetrahydrofuran ether polyol or polyoxypropylene ether-tetrahydrofuran polyol.

The polyurethane product as described above has a number-average molecular weight of 3000-10000, a dispersion index of 1.6-2.8, and a glass transition temperature (Tg) of -80-20°C as measured by DSC.

3. Application of polyurethane interfacial coupling agent

The application of polyurethane interfacial coupling agent is used in the preparation of agricultural residue fiber and thermoplastic composite material.

The polyurethane interface coupling agent of the present invention is blended with agricultural residue fibers and thermoplastics at normal temperature, which can realize the pretreatment of agricultural residue fibers/thermoplastic composite materials, and the consumption of polyurethane interface coupling agent accounts for 1/2 of the weight of agricultural residue fibers. 0.2-10%.

The agricultural residue fiber mentioned above refers to rice, wheat, corn or millet grain crops, or peanut, rapeseed, flax or sesame oil crops, or cotton, jute, ramie, hemp or flax crops, or sugar cane or residues of beet sugar crops, or a mixture of one or more of these agricultural residues.

The thermoplastics mentioned above refer to low-density or high-density polyethylene, polypropylene, polyvinyl chloride, polystyrene, or a mixture of two or more. Thermoplastics can be virgin plastics or recycled plastics, or virgin plastics and Mixture of recycled plastics.

The application of the polyurethane interfacial coupling agent of the present invention is to use the coupling agent for the pretreatment of agricultural residue fiber/thermoplastic composite material raw materials, after blending with the polyurethane interfacial coupling agent of the present invention, the blend is then The board of the composite material can be prepared through material laying, pre-pressing, hot pressing and post-treatment, and the obtained board has good physical and mechanical properties, and the industrialization of the composite board will produce higher social and economic benefits.

The outstanding feature of the preparation method of the present invention is that there is no waste gas, waste liquid, and waste solid. Compared with the preparation of traditional silane and titanate coupling agents, it has simple production technology, low synthesis cost, and low energy consumption for raw material pretreatment. Less features.

The polyurethane interfacial coupling agent of the present invention can effectively improve the bonding strength of the interface of the composite material, reduce the interfacial tension, and improve the physical and mechanical properties of the composite material for the pretreatment of the remaining agricultural fiber and the plastic raw material; the composite material has no harmful effects such as formaldehyde. The release of substances, similar to wood, can be sawed, planed, riveted, nailed, degraded, recycled, and also has properties that wood cannot match, such as isotropy, water resistance, insect resistance, corrosion resistance, and excellent durability; It has broad application prospects in construction, transportation, packaging, public facilities, etc.

Description of drawings

Fig. 1 is the FTIR diagram of the polyurethane interfacial coupling agent prepared in Example 1 of the present invention.

Detailed ways

The present invention is further described below in conjunction with embodiment, but protection scope of the present invention is not limited to embodiment, and the change that the technical solution of the present invention is made by the professional of this field all should belong in protection scope of the present invention.

Example 1:

In a reaction kettle equipped with a stirrer, a thermometer and a reflux device, the polyoxypropylene ether triols with a molecular weight of 300 and 3000, and the polyoxyethylene ether diols with a molecular weight of 1000 are mixed according to the molar ratio of free hydroxyl groups of 1:2 : Blending in a ratio of 6, then add liquefied diphenylmethane diisocyanate (MDI), the amount of MDI added is based on the free NCO contained in MDI and the free OH contained in polyoxypropylene ether trihydric alcohol and polyoxyethylene ether glycol. Control the molar ratio of 4:1, heat to 80°C, keep the temperature constant for 60 minutes, then take the content every 15 minutes for chemical titration analysis until the free NCO% is constant, then cool and pack.

Example 2: As described in Example 1, the difference is that the used isocyanate is polyphenyl polymethylene polyisocyanate (PAPI).

Example 3: As described in Example 1, except that the isocyanate used is water-emulsifiable MDI.

Example 4: As described in Example 1, the difference is that the used isocyanate is a blend of MDI and PAPI, and the molar ratio of MDI and PAPI is 3:1.

Embodiment 5: As described in Example 1, the difference is that the polyoxyethylene ether glycol with a molecular weight of 1000 is replaced by a mixture of polyoxyethylene ether glycol and polyoxypropylene ether-tetrahydrofuran glycol, The molar ratio of polyoxyethylene ether diol to polyoxypropylene ether-tetrahydrofuran diol is 1:1.

Embodiment 6:

In a reactor equipped with a stirrer, a thermometer and a reflux device, the polyoxypropylene ether triols with a molecular weight of 300 and 3000, and the polyoxyethylene ether diols with a molecular weight of 600 and 1000 were mixed according to the molar ratio of free hydroxyl groups of 1 : Blending in the ratio of 2:2:4, then add the blend of MDI and PAPI, the molar ratio of MDI and PAPI is 1:1, the free NCO contained in MDI and PAPI is mixed with polyoxypropylene ether triol and polyethylene oxide The molar ratio of the free OH contained in the ether diol is controlled at 12:1, heated to 60° C., kept at a constant temperature for 120 minutes, and the content is taken every 15 minutes for chemical titration analysis until the free NCO% is constant, cooled, and packaged.

Example 7: As described in Example 6, the difference is that the molar ratio of the free NCO contained in the isocyanate blend to the free OH contained in the polyol blend is 20:1.

Example 8: As described in Example 6, the difference is that the polyoxypropylene ether triols with a molecular weight of 300 and 3000 are replaced by polyoxypropylene ether triols with a molecular weight of 2000.

Example 9: As described in Example 6, except that the isocyanate used is water-emulsifiable MDI.

Embodiment 10: the application of polyurethane interfacial coupling agent

Under normal temperature conditions, the polyurethane interface coupling agent of the present invention, which accounts for 2.5% of the weight of agricultural residue fibers, is blended with wheat straw and recycled polyethylene, spread, pre-pressed, hot-pressed, and post-treated to obtain the composite material plate. The mass ratio of agricultural residue fibers to thermoplastics is 80/20. Table 1 compares the physical and mechanical properties of the composite material with the wheat straw/recycled polyethylene composite material without coupling agent.

Table 1 compare items Density (g/cm ³ ) Internal bonding strength (MPa) Bond strength after 2h boiling water (MPa) Static bending strength (MPa) Elastic modulus (MPa) 24h water absorption swelling rate (%) Composite without coupling agent 0.9852 0.1296 0.0123 11.87 1619.20 37.86 Composite material with coupling agent 1.0821 0.8521 0.3428 39.59 4485.30 6.8318

As can be seen from Table 1, the interfacial coupling agent synthesized by the present invention has a remarkable effect on improving the physical and mechanical properties of the wheat straw/recycled polyethylene composite material, and the raw materials and good physical and mechanical properties of the composite material indicate that the composite material The industrialization of the industry will surely produce higher social and economic benefits.

Claims (10)

1. polyurethane interface coupling agent, it is characterized in that this coupling agent number-average molecular weight is 3000～10000, dispersion index is 1.6～2.8, second-order transition temperature is pressed determine with dsc method and is-80～20 ℃, be to be blend in 2: 1～20: 1 with isocyanic ester and polyvalent alcohol by free isocyanate groups and hydroxyl mol ratio, 60～150 ℃ of heating make.

2. the preparation method of a polyurethane interface coupling agent, step is as follows:

Is blend in 2: 1～20: 1 with isocyanic ester and polyvalent alcohol by the mol ratio of free isocyanate groups and hydroxyl, 60～150 ℃ of heating, be 60～240 minutes heat-up time, periodically get reactant and carry out chemistry titration or infrared spectra detection, percentage composition until isocyanate group is constant, cooling, discharging gets product polyurethane interface coupling agent.

3. the preparation method of polyurethane interface coupling agent as claimed in claim 2, it is characterized in that described isocyanic ester, be meant that molecular weight is 100～500 aromatic series that contains free isocyanate groups or fatty compounds, specifically be selected from one of following or combination: tolylene diisocyanate, the tripolymer of modification tolylene diisocyanate and tolylene diisocyanate, diphenylmethanediisocyanate, the liquefaction diphenylmethanediisocyanate, polyphenyl polymethylene polyisocyanates, isophorone diisocyanate, dicyclohexyl methane diisocyanate, methyl cyclohexylene vulcabond, or emulsible tolylene diisocyanate of water or polyphenyl polymethylene polyisocyanates.

4. the preparation method of polyurethane interface coupling agent as claimed in claim 2 is characterized in that described polyvalent alcohol, is meant that molecular weight is the mixture of 300～8000 polyhydric alcohol polymer.

5. the preparation method of polyurethane interface coupling agent as claimed in claim 4, it is characterized in that described polyhydric alcohol polymer is the polymkeric substance of polyether glycol, the perhaps mixture of polymers of the polymkeric substance of polyether glycol and polyester polyol, the functionality of polyether glycol polymkeric substance, polyol polyester polymer is 2 or 3.

6. the preparation method of polyurethane interface coupling agent as claimed in claim 5 is characterized in that described polyether glycol is selected from polyoxytrimethylene ethoxylated polyhydric alcohol, polyoxyethylene ethoxylated polyhydric alcohol, polytetrahydrofuran ethoxylated polyhydric alcohol or polyoxytrimethylene ether-tetrahydrofuran (THF) polyvalent alcohol.

7. the application of the described polyurethane interface coupling agent of claim 1 is used for the preparation of agricultural wastes fiber and thermoplastic plastic composite material.

8. the application of polyurethane interface coupling agent as claimed in claim 7, it is characterized in that under the polyurethane interface coupling agent normal temperature and the blend of agricultural residue fiber peacekeeping thermoplastics, realization is to the pre-treatment of agricultural wastes fiber/thermoplastic plastic composite material, and the consumption of polyurethane interface coupling agent accounts for 0.2～10% of agricultural wastes fiber weight.

9. the application of polyurethane interface coupling agent as claimed in claim 7, it is characterized in that described agricultural wastes fiber is meant paddy rice, wheat, corn or millet food crop, or peanut, rape, flax or sesame oil crops, or cotton, yellow bluish dogbane, ramie, hemp or flax crudefiber crop, or the residuum of sugarcane or beet sugar crop, or above one or more the mixture of agricultural wastes.

10. the application of polyurethane interface coupling agent as claimed in claim 7, it is characterized in that described thermoplastics is one or more the mixture in index and low density or high density polyethylene(HDPE), polypropylene, polyvinyl chloride, the polystyrene, thermoplastics can be new plastic or the mixture that reclaims plastics or new plastic and recovery plastics.