A tetraene-terminated polyether adhesive and a synthesis method thereof

Abstract

The invention discloses a terminal tetraene polyether adhesive and a synthesis method thereof. The method uses 2,7-octadienol and propylene oxide as raw materials, boron trifluoride ether complex as a catalyst, and obtains octadienyl polypropylene oxide alcohol through cationic ring-opening polymerization; then uses octadienyl polypropylene oxide alcohol and hexamethylene diisocyanate as raw materials, dibutyltin dilaurate as a catalyst, and obtains terminal tetraene polypropylene oxide through addition reaction, that is, terminal tetraene polyether adhesive. The present invention can improve the mechanical properties of an elastomer, and the polyisoxazoline elastomer prepared using the terminal tetraene polyether adhesive of the present invention as a raw material has a tensile strength of 1.6MPa at 20°C and an elongation at break of 126%.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a terminal tetraene polyether adhesive. The compound can be used as an adhesive for solid propellants. Background Art

[0002] Adhesives such as terminal hydroxyl ethylene oxide-tetrahydrofuran random copolyether (PET), terminal hydroxyl polytetrahydrofuran and polyethylene glycol block copolyether (HTPE) have been widely studied and applied in composite solid propellants. This type of terminal hydroxyl polyether adhesive has the advantages of good physical and chemical properties, low glass transition temperature and viscosity, good process and mechanical properties, and can accommodate a relatively high solid content. It is generally used in combination with isocyanate curing agent to cure to form polyurethane elastomer. However, when curing with isocyanate curing agent, there are problems such as harsh curing conditions, water sensitivity, and high curing temperature.

[0003] In order to solve the above problems existing in the curing of hydroxyl-terminated polyether adhesives, researchers have developed a polyisoxazoline cross-linking curing system based on olefinic adhesive / nitrile oxide curing agent curing, and designed and prepared a new type of olefinic polyether adhesive. For example, Mo Hongchang et al. reported a olefinic polyether adhesive in "Synthesis and Characterization of Hydroxyl-Terminated PAGE-PTMEG-PAGE Block Copolyethers" Energetic Materials, 2018, 26(9): 749-752, namely, hydroxyl-terminated polyallyl glycidyl ether polytetrahydrofuran polyallyl glycidyl ether triblock copolyether (PAGE-PTMEG-PAGE for short), and its structural formula is as follows:

[0004]

[0005] The glass transition temperature of the PAGE-PTMEG-PAGE adhesive is -80.3°C, and it is a low-viscosity liquid at room temperature, with good low-temperature and process performance. However, the tensile strength of the polyisoxazoline elastomer film obtained after the PAGE PTMEG PAGE adhesive is cured with tetramethylterephthalonitrile oxide (TTNO) curing agent is 1.2MPa at 20°C, and the elongation at break is 83%, and the mechanical properties such as tensile strength and elongation at break are all low. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a tetraene-terminated polyether adhesive and a synthesis method thereof, so as to overcome the problem that the mechanical properties of the above-mentioned elastomer film are relatively low.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0008] A tetraene-terminated polyether adhesive, the structural formula of which is as follows:

[0009]

[0010] Wherein, n=10 to 60, which is an integer.

[0011] A method for synthesizing a tetraene-terminated polyether adhesive comprises the following steps: using 2,7-octadienol and propylene oxide as raw materials, using boron trifluoride·ethyl ether complex as a catalyst, and obtaining octadienyl polypropylene oxide alcohol through a cationic ring-opening polymerization reaction; and then using octadienyl polypropylene oxide alcohol and hexamethylene diisocyanate as raw materials, using dibutyltin dilaurate as a catalyst, and obtaining tetraene-terminated polypropylene oxide through an addition reaction, namely, the tetraene-terminated polyether adhesive.

[0012] The present invention also includes the following technical features:

[0013] Specifically, the molar ratio of the 2,7-octadienol, propylene oxide and boron trifluoride·ethyl ether complex is 1:10-60:0.2-0.6.

[0014] Specifically, the molar ratio of the octadienyl polypropylene oxide alcohol to hexamethylene diisocyanate is 2:1, and the mass ratio of the octadienyl polypropylene oxide alcohol to dibutyltin dilaurate is 1:0.0001-0.01.

[0015] Specifically, the method comprises the following steps:

[0016] Step 1, synthesis of octadienyl polypropylene oxide alcohol: add dichloromethane, 2,7-octadienol and boron trifluoride·ether complex into a reaction flask, stir, cool to 0°C in an ice-water bath, start to drop propylene oxide, continue to react after the dropwise addition is complete, add Na2CO3 aqueous solution to neutralize and terminate the reaction, wash the organic phase with water until neutral, and concentrate to obtain a colorless viscous liquid, which is octadienyl polypropylene oxide alcohol;

[0017] Step 2, synthesis of tetraene-terminated polypropylene oxide: at room temperature, add octadienyl polypropylene oxide alcohol, dibutyltin dilaurate and hexamethylene diisocyanate into a reaction bottle, heat and react to obtain a light yellow viscous liquid, which is the tetraene-terminated polyether adhesive.

[0018] Specifically, in step 1, the stirring time is 30 min to 1 h.

[0019] Specifically, in step 1, the dripping time of propylene oxide is 6 hours to 12 hours, and the reaction is continued for 6 hours to 15 hours after the dripping is completed.

[0020] Specifically, in step 2, the mixture is heated to 60° C. to 70° C. and reacted for 6 h to 12 h.

[0021] Compared with the prior art, the present invention has the following technical effects:

[0022] The tetraolefin-terminated polyether adhesive of the present invention has four reactive double bond groups introduced at both ends of the molecular chain, and has high functionality. On the other hand, a carbamate group with strong hydrogen bonding between groups is introduced in the middle of the main chain. The adhesive is used for synthesizing polyisoxazoline elastomers, which increases the content of hard segments and the regularity of the network structure, promotes the microphase separation of the elastomer, and thus improves the mechanical properties.

[0023] The polyisoxazoline elastomer prepared using the tetraene-terminated polyether adhesive of the present invention as raw material has a tensile strength of 1.6 MPa at 20° C. and an elongation at break of 126%, while the polyisoxazoline elastomer prepared using the PAGE PTMEG PAGE adhesive in the comparative literature has a tensile strength of 1.2 MPa at 20° C. and an elongation at break of 83%. DETAILED DESCRIPTION

[0024] The concept of the present invention is that the mechanical properties of the PAGE PTMEG PAGE based polyisoxazoline elastomer are low because the reactive double bond groups in the PAGE PTMEG PAGE adhesive are distributed on the side chains at both ends of the polyether molecular chain, but the number of the double bond groups is large, and the randomness of the olefinic group reaction during curing is large and difficult to control. In order to improve the mechanical properties of the elastomer, the present invention synthesizes a terminal tetraolefinic polyether adhesive, wherein the number of olefinic groups is controllable and distributed at both ends of the polyether molecular chain, which can improve the integrity of the cross-linked network structure formed after curing.

[0025] The tetraene-terminated polyether adhesive of the present invention has the structural formula shown below:

[0026]

[0027] Wherein, n=10 to 60, which is an integer.

[0028] The synthesis route of the tetraene-terminated polyether adhesive of the present invention is as follows:

[0029]

[0030] Wherein, n=10 to 60, which is an integer.

[0031] The method for synthesizing the tetraene-terminated polyether adhesive of the present invention comprises the following steps:

[0032] (1) Octadienyl polypropylene oxide alcohol is obtained by cationic ring-opening polymerization using 2,7-octadienol and propylene oxide as raw materials and boron trifluoride·ethyl ether complex as catalyst.

[0033] (2) Using octadienyl polypropylene oxide alcohol and hexamethylene diisocyanate as raw materials and dibutyltin dilaurate as a catalyst, a terminal tetraene polypropylene oxide is obtained through an addition reaction, which is the terminal tetraene polyether adhesive of the present invention.

[0034] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0035] Test equipment:

[0036] (1) The infrared spectrum was measured using a Nexus 870 Fourier transform infrared spectrometer from Nicolet, USA.

[0037] (2) The hydroxyl value was tested using the phthalic anhydride-pyridyl acylation method.

[0038] (3) Number average molecular weight

[0039] Equipment: GPC-50 gel permeation chromatograph from PL Company, UK;

[0040] GPC test conditions: chromatographic columns are PLgel MIXED-E in series; mobile phase is THF; column temperature is 40°C; detector is a differential refractometer.

[0041] (4) Mechanical properties

[0042] Equipment: Instron 4505 universal material testing machine from Instron, USA;

[0043] Test method: According to GB / T770B-2005 method 413.1.

[0044] Embodiment 1:

[0045] This embodiment provides a tetraene-terminated polyether adhesive and a synthesis method thereof, the synthesis method comprising the following steps:

[0046] Step 1, Synthesis of Octadienyl Polypropylene Oxide Alcohol

[0047] Add 15 mL of dichloromethane, 1.26 g of 2,7-octadienol and 0.43 g of boron trifluoride·ether complex into the reaction flask. After stirring for 30 min, cool to 0°C in an ice-water bath and begin to dropwise add 14.5 g of propylene oxide for 10 h. After the dropwise addition is complete, continue the reaction for 8 h. Add Na2CO3 aqueous solution to neutralize and terminate the reaction. Wash the organic phase with water until it is neutral and concentrate to obtain a colorless viscous liquid.

[0048] Structure identification:

[0049] IR (KBr, cm-1 ): 3460(-OH), 1646(C=C), 1123(COC).

[0050] Molecular weight and distribution: Mn=1560, Mw=2371, Mw / Mn=1.52.

[0051] Hydroxyl value: 35.24 mgKOH / g.

[0052] The above analytical data confirmed that the synthesized compound was octadienyl polyoxypropylene alcohol.

[0053] Step 2, Synthesis of Tetraene-Terminated Polypropylene Oxide

[0054] At room temperature, 15.6 g of octadienyl polyoxypropylene alcohol, 0.02 g of dibutyltin dilaurate and 0.84 g of hexamethylene diisocyanate were added to a reaction bottle, heated to 65° C. and reacted for 8 h to obtain a light yellow viscous liquid.

[0055] Structure identification:

[0056] IR (KBr, cm -1 ): 3309(-NH-), 1740(C=O), 1646(C=C), 1123(COC).

[0057] Molecular weight and distribution: Mn = 3265, Mw = 5420, Mw / Mn = 1.66.

[0058] The above analytical data confirmed that the synthesized compound is a tetraene-terminated polypropylene oxide.

[0059] Application performance of the tetraene-terminated polyether adhesive of the present invention

[0060] (1) Evaluation of compatibility with nitrile oxide curing agents

[0061] Tetramethylterephthalonitrile oxide (TTNO) was selected as a curing agent, and the miscibility and reactivity of the tetraene-terminated polyether adhesive of the present invention with the curing agent were investigated.

[0062] The tetraene-terminated polyether adhesive and the TTNO curing agent of the present invention have good miscibility in dichloromethane, the mixed liquid is clear and transparent, and the formed mixed liquid can smoothly undergo a curing reaction at 20-30°C.

[0063] (2) Mechanical properties of elastomers

[0064] The TTNO curing agent is reacted with the PAGE PTMEG PAGE adhesive and the tetraene-terminated polyether adhesive of the present invention to generate a polyisoxazoline elastomer, and its mechanical properties are shown in Table 1.

[0065] Table 1 Effect of adhesive on mechanical properties of elastomer (20℃)

[0066]

[0067] It can be seen that the mechanical properties of the elastomer formed by curing the tetraene-terminated polyether adhesive of the present invention are significantly better than those of the elastomer formed by curing the PAGEPTMEG PAGE adhesive.

Claims

1. A polyisoxazoline elastomer, characterized in that The polyisoxazoline elastomer is produced by reacting a tetraene-terminated polyether adhesive and tetramethyl terephthalonitrile oxide; the structural formula of the tetraene-terminated polyether adhesive is as follows: Wherein, n=10~60, is an integer; The synthesis method of the tetraene-terminated polyether adhesive is as follows: the method uses 2,7-octadienol and propylene oxide as raw materials, boron trifluoride·ether complex as a catalyst, and obtains octadienyl polypropylene oxide alcohol through a cationic ring-opening polymerization reaction; then uses octadienyl polypropylene oxide alcohol and hexamethylene diisocyanate as raw materials, dibutyltin dilaurate as a catalyst, and obtains tetraene-terminated polypropylene oxide through an addition reaction, namely, the tetraene-terminated polyether adhesive.

2. The polyisoxazoline elastomer according to claim 1, characterized in that The molar ratio of the 2,7-octadienol, propylene oxide and boron trifluoride·ethyl ether complex is 1:10-60:0.2-0.

6.

3. The polyisoxazoline elastomer according to claim 2, characterized in that The molar ratio of the octadienyl polypropylene oxide alcohol to hexamethylene diisocyanate is 2:1, and the mass ratio of the octadienyl polypropylene oxide alcohol to dibutyltin dilaurate is 1:0.0001-0.

01.

4. The polyisoxazoline elastomer according to claim 3, characterized in that The method comprises the following steps: Step 1, synthesis of octadienyl polypropylene oxide alcohol: add dichloromethane, 2,7-octadienol and boron trifluoride·ether complex into a reaction flask, stir, cool to 0°C in an ice-water bath, start to drop propylene oxide, continue the reaction after the dropwise addition is complete, add Na2CO3 aqueous solution to neutralize and terminate the reaction, wash the organic phase with water until neutral, and concentrate to obtain a colorless viscous liquid, which is octadienyl polypropylene oxide alcohol; Step 2, synthesis of tetraene-terminated polypropylene oxide: at room temperature, add octadienyl polypropylene oxide alcohol, dibutyltin dilaurate and hexamethylene diisocyanate into a reaction bottle, heat and react to obtain a light yellow viscous liquid, which is the tetraene-terminated polyether adhesive.

5. The polyisoxazoline elastomer according to claim 4, characterized in that In step 1, the stirring time is 30 min to 1 h.

6. The polyisoxazoline elastomer according to claim 4, characterized in that In the step 1, the dripping time of propylene oxide is 6 hours to 12 hours, and the reaction is continued for 6 hours to 15 hours after the dripping is completed.

7. The polyisoxazoline elastomer according to claim 4, characterized in that In the step 2, the temperature is heated to 60° C. to 70° C. and the reaction is carried out for 6 h to 12 h.

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