Polylactic acid polyol as well as preparation method and application thereof

Abstract

The invention discloses polylactic acid polyol as well as a preparation method and application thereof. The preparation method comprises the following steps: performing a heating reaction on zinc salt, organic ammonium salt and bis (ethylene carbonate) ether to prepare an in-situ catalyst; anions of the organic ammonium salt are selected from any one of bromide ions, chloride ions and iodide ions; and adding a lactide monomer, and carrying out polymerization reaction to obtain the polylactic acid polyol. The polylactic acid polyol prepared by the invention has a flexible chain segment, can provide better flexibility, and can be applied to preparation of a polyurethane material.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polylactic acid polyol and a preparation method and application thereof. Background Art

[0002] Polylactic acid, also known as polylactide, is a widely used bio-based chemical that is derived from the fermentation of natural starch (such as rice and corn) or prepared from kitchen waste and cellulose. Polylactic acid polyol prepared by ring-opening polymerization of lactic acid has excellent biocompatibility and degradability, and can eventually be completely degraded into CO 2 and H 2 O, in line with the needs of sustainable development.

[0003] At present, the preparation method of polylactic acid polyol is mostly to use different alcohols as initiators, and to use lactide as the main raw material to carry out lactide ring-opening polymerization under the action of a catalyst. For example, CN109265660 A, CN109293901A, etc. reported that lactide monomer and other materials were used as raw materials, and metal catalysts such as magnesium and neodymium were used to catalyze lactone ring-opening polymerization to prepare polylactic acid polyol. However, these methods are difficult to remove harmful metals, and the catalytic system used has low reaction activity and low yield, and has high requirements on equipment. The cost of the final prepared product is high and the safety is low, which limits its application in the fields of biomedicine, packaging and microelectronics.

[0004] In addition, polylactic acid polyols with flexible segments can be used to prepare flexible materials, which can expand the application scenarios of polylactic acid polyols. However, the current polylactic acid polyols are relatively few in variety and not flexible enough, which limits the application of polylactic acid polyols to a certain extent. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a polylactic acid polyol and a preparation method and application thereof. The polylactic acid polyol has low preparation cost, high safety and good flexibility.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In one aspect, the present invention provides a method for preparing polylactic acid polyol, comprising the following steps:

[0008] Step 1, preparing an in-situ catalyst by heating a zinc salt, an organic ammonium salt and bis(ethylene carbonate) ether; the anion of the organic ammonium salt is selected from any one of bromide ion, chloride ion and iodide ion;

[0009] Step 2: adding lactide monomer to obtain the polylactic acid polyol through polymerization reaction.

[0010] In the technical solution of the present invention, the in-situ catalyst obtained by ring-opening bis(vinyl carbonate) ether can initiate the polymerization reaction of lactide.

[0011] As a preferred embodiment, the zinc salt is selected from at least one of zinc chloride and zinc bromide; the organic ammonium salt is selected from at least one of tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylammonium iodide compounds.

[0012] In the technical solution of the present invention, the structural formula of the bis(ethylene carbonate) ether is:

[0013]

[0014] Preferably, the mass ratio of the zinc salt, the organic ammonium salt and the bis(ethylene carbonate) ether is 1:10-50:30-50.

[0015] Preferably, in step 1, the temperature of the heating reaction is 180-220° C., and the time of the heating reaction is 1-3 hours;

[0016] In the technical solution of the present invention, the heating reaction will produce gas and needs to be carried out in a pressure-resistant device; the pressure that the pressure-resistant device can withstand is ≥1MPa.

[0017] As a preferred embodiment, the mass ratio of the bis(vinyl carbonate) ether in step 1 to the lactide monomer in step 2 is 1:30-60.

[0018] Preferably, in step 2, the polymerization reaction temperature is 130-180° C. and the time is 1-2 hours.

[0019] In some specific embodiments, step 2 further comprises the step of adding a precipitant to separate and obtain the polylactic acid polyol, and the specific process is: adding a precipitant, removing the solvent, and drying; the precipitant is selected from any one of methanol and ethanol.

[0020] In another aspect, the present invention provides polylactic acid polyol obtained by the above preparation method.

[0021] In the technical solution of the present invention, the general structural formula of the polylactic acid polyol is as shown in formula (1):

[0022]

[0023] In formula (1), m is 3 to 20, n is 3 to 20, and X is a halogen atom.

[0024] In the technical solution of the present invention, the halogen atom is selected from any one of bromine, chlorine and iodine.

[0025] In another aspect, the present invention provides use of the polylactic acid polyol in preparing a polyurethane material.

[0026] In another aspect, the present invention provides a polyurethane material prepared from the above-mentioned polylactic acid polyol, wherein the preparation comprises the following steps:

[0027] The polylactic acid polyol and polyisocyanate are reacted under the action of a catalyst to obtain the polyurethane material.

[0028] As a preferred embodiment, the polyisocyanate is selected from at least one of toluene diisocyanate and diphenylmethane diisocyanate;

[0029] Preferably, the catalyst is a tin catalyst, specifically dibutyltin dilaurate, stannous octoate, stannous chloride, tin lactate, stannous octoate, etc.;

[0030] Preferably, the reaction is carried out at room temperature, and the reaction time is 1 to 2 hours;

[0031] Preferably, the mass ratio of the polylactic acid polyol to the polyisocyanate is 28-65:100;

[0032] In some specific embodiments, a blowing agent is added to the reaction; the blowing agent is water.

[0033] The beneficial effects brought by the present invention are as follows:

[0034] In order to solve the technical problems of high preparation cost, low safety, poor flexibility and complex preparation method of polylactic acid polyol, which is not conducive to promotion and application, the present invention prepares polylactic acid polyol with a specific structure by using a catalytic system and initiator with high catalytic activity.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] (1) The polylactic acid polyol provided by the present invention has an ether bond in the chain segment, the molecular chain is easy to rotate, and the molecular structure has two hydroxyl groups, which can provide a more suitable cross-linking degree and improve the flexibility of the material prepared using the polylactic acid polyol, and has a good application prospect;

[0037] (2) The polylactic acid polyol provided by the present invention has a high reaction activity of the catalytic system, is non-toxic, safe and low-cost, can improve the yield, reduce the preparation cost, expand its application range, and has large-scale production;

[0038] (3) The polylactic acid polyol provided by the present invention contains both polylactic acid long chain segments of appropriate length and short side chains with halogen, which can improve its compatibility with other systems; the polylactic acid segments of appropriate length can enhance the tensile strength of the prepared polylactic acid polyol, which is conducive to obtaining better mechanical properties; in addition, the polylactic acid segments are biodegradable, and the polyol structure helps it to further decompose in the environment, so the prepared polylactic acid polyol has good environmental protection.

[0039] (4) The polyurethane material prepared by the polylactic acid polyol of the present invention has a lower indentation hardness and has higher softness when used as a biomaterial or packaging material, thereby improving user comfort and cushioning capacity. DETAILED DESCRIPTION

[0040] The following embodiments are only some embodiments of the present invention, rather than all embodiments. Therefore, the detailed description in the embodiments of the present invention provided below is not intended to limit the scope of the present invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the protection scope of the present invention.

[0041] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0042] Example 1

[0043] This embodiment prepares a polylactic acid polyol, and the preparation method is as follows:

[0044] Step 1, 0.5 g of bis(vinyl carbonate) ether, 0.01 g of zinc chloride, and 0.3 g of tetrabutylammonium chloride are mixed, and reacted at 200° C. and a pressure-resistant container of 1 MPa for 1 h to obtain an in-situ catalyst;

[0045] Step 2, adding 18 g of purified lactide (LA) monomer to the above in-situ catalyst, and reacting at 160° C. for 1 h;

[0046] Step 3: After the reaction is completed, methanol is added to the reaction system for precipitation. After removing the solvent, the mixture is vacuum dried at 40° C. for 48 hours to obtain polylactic acid polyol.

[0047] After characterization, the structural formula of the polylactic acid polyol prepared in this example is:

[0048]

[0049] Example 2

[0050] This embodiment prepares a polylactic acid polyol, and the preparation method is as follows:

[0051] Step 1, 0.4 g of bis(vinyl carbonate) ether, 0.01 g of zinc bromide, and 0.1 g of tetrabutylammonium bromide were mixed, and reacted at 200° C. and a pressure-resistant container of 1 MPa for 1.5 h to obtain an in-situ catalyst;

[0052] Step 2, adding 18 g of LA monomer to the above in-situ catalyst and reacting at 180° C. for 1 h;

[0053] Step 3: After the reaction is completed, methanol is added to the reaction system for precipitation, and then the solvent is removed and vacuum dried at 40° C. for 48 hours to obtain polylactic acid polyol.

[0054] After characterization, the structural formula of the polylactic acid polyol prepared in this example is:

[0055]

[0056] Example 3

[0057] This embodiment prepares a polylactic acid polyol, and the preparation method is as follows:

[0058] Step 1, 0.3 g of bis(vinyl carbonate) ether, 0.01 g of zinc chloride, and 0.3 g of tetrabutylammonium chloride are mixed, and reacted at 200° C. and a pressure-resistant container of 1 MPa for 1.5 h to obtain an in-situ catalyst;

[0059] Step 2, adding 16.2 g of LA monomer to the above in-situ catalyst and reacting at 130° C. for 2 h;

[0060] Step 3: After the reaction is completed, methanol is added to the reaction system for precipitation, and then the solvent is removed and vacuum dried at 40° C. for 48 hours to obtain polylactic acid polyol.

[0061] After characterization, the structural formula of the polylactic acid polyol prepared in this example is:

[0062]

[0063] Example 4

[0064] This embodiment prepares a polylactic acid polyol, and the preparation method is as follows:

[0065] Step 1, 0.5 g of bis(vinyl carbonate) ether, 0.01 g of zinc chloride, and 0.5 g of tetrabutylammonium iodide were mixed, and reacted at 200° C. and in a 1 MPa pressure-resistant container for 1 h to obtain an in-situ catalyst;

[0066] Step 2, adding 18 g of LA monomer to the above in-situ catalyst and reacting at 160° C. for 2 h;

[0067] Step 3: After the reaction is completed, methanol is added to the reaction system for precipitation, and then the solvent is removed and vacuum dried at 40° C. for 48 hours to obtain polylactic acid polyol.

[0068] After characterization, the structural formula of the polylactic acid polyol prepared in this example is:

[0069]

[0070] Example 5

[0071] This embodiment prepares a polylactic acid polyol, and the preparation method is as follows:

[0072] Step 1, 0.5 g of bis(vinyl carbonate) ether, 0.01 g of zinc bromide, and 0.1 g of tetrabutylammonium bromide were mixed, and reacted in a container at 210° C. and 1 MPa pressure for 1 h to obtain an in-situ catalyst;

[0073] Step 2, adding 18 g of LA monomer to the above in-situ catalyst and reacting at 160° C. for 1 h;

[0074] Step 3: After the reaction is completed, ethanol is added to the reaction system for precipitation, and then the solvent is removed and vacuum dried at 40° C. for 48 hours to obtain polylactic acid polyol.

[0075] After characterization, the structural formula of the polylactic acid polyol prepared in this example is:

[0076]

[0077] Example 6

[0078] This embodiment prepares a polylactic acid polyol, and the preparation method is as follows:

[0079] Step 1, 0.5 g of bis(vinyl carbonate) ether, 0.01 g of zinc bromide, and 0.5 g of tetrabutylammonium iodide were mixed, and reacted in a container at 220° C. and 1 MPa pressure for 2 h to obtain an in-situ catalyst;

[0080] Step 2, adding 15 g of LA monomer to the above in-situ catalyst and reacting at 160° C. for 1 h;

[0081] Step 3: After the reaction is completed, methanol is added to the reaction system for precipitation, and then the solvent is removed and vacuum dried at 40° C. for 48 hours to obtain polylactic acid polyol.

[0082] After characterization, the structural formula of the polylactic acid polyol prepared in this example is:

[0083]

[0084] Comparative Example 1

[0085] In this comparative example, a polylactic acid polyol was prepared. The preparation method was the same as that in Example 1, except that the bis(ethylene carbonate) ether added in step 1 was replaced by 0.5 g of ethylene glycol diglycidyl ether.

[0086] Comparative Example 2

[0087] In this comparative example, a polylactic acid polyol was prepared. The preparation method was the same as that in Example 1, except that LA monomer was replaced by butyrolactone.

[0088] Comparative Example 3

[0089] This comparative example prepared a polylactic acid polyol, and the preparation method is as follows:

[0090] Step 1, 0.5 g of bis(vinyl carbonate) ether, 0.005 g of zinc chloride, and 0.3 g of tetrabutylammonium chloride are mixed, and reacted at 200° C. and a pressure-resistant container of 1 MPa for 1 h to obtain an in-situ catalyst;

[0091] Step 2, adding 18 g of purified LA monomer to the above in-situ catalyst, and reacting at 160° C. for 1 h;

[0092] Step 3: After the reaction is completed, methanol is added to the reaction system for precipitation, and then the solvent is removed and vacuum dried at 40° C. for 48 hours to obtain polylactic acid polyol.

[0093] Application Examples

[0094] The polylactic acid polyol prepared in the above examples and comparative examples and toluene diisocyanate (TDI) were prepared into a polyurethane material, and the preparation process was as follows:

[0095] 10 g of toluene diisocyanate (TDI), 6 g of polylactic acid polyol, 0.2 g of dibutyltin dilaurate and 0.8 g of water were mixed evenly, and reacted at room temperature for 1.5 hours to obtain a reaction liquid; the reaction liquid was foamed and aged at normal pressure for 24 hours to obtain the polyurethane sponge material.

[0096] The catalytic activity of the catalytic system in the process of preparing polylactic acid polyol in the above examples and comparative examples (the higher the output in the same time, the higher the activity), the preparation yield of polylactic acid polyol were tested, and the flexibility of the prepared polyurethane material was tested. The test results are shown in Table 1. The flexibility of the polyurethane material can be characterized by measuring the indentation hardness, and the indentation hardness is tested according to the GB10807-2006 standard.

[0097] Table 1

[0098] Test items Yield TOF value Indentation hardness Example 1 85.3％ <![CDATA[3034h -1 ]]> 1.53 Example 2 71.2％ <![CDATA[2543h -1 ]]> 1.55 Example 3 57.8％ <![CDATA[1026h -1 ]]> 1.50 Example 4 98.0％ <![CDATA[3485h -1 ]]> 1.52 Example 5 72.1％ <![CDATA[2464h -1 ]]> 1.48 Example 6 69.8％ <![CDATA[3357h -1 ]]> 1.46 Comparative Example 1 10.1％ <![CDATA[359h -1 ]]> 1.58 Comparative Example 2 13.7％ <![CDATA[487h -1 ]]> 1.65 Comparative Example 3 38.7％ <![CDATA[1375h -1 ]]> 1.67

[0099] It can be seen from the test results in Table 1 that Comparative Example 1 replaces bis(ethylene carbonate) ether with ethylene glycol diglycidyl ether, and Comparative Example 2 replaces LA monomer with butyrolactone during the preparation process, resulting in lower catalytic activity of the catalytic system in Comparative Example 1 and Comparative Example 2, lower preparation yield, and due to the shorter molecular chain of the prepared polylactic acid polyol, the flexibility of the polyurethane material prepared using it is poor; the polylactic acid polyol prepared in Comparative Example 3 has a reduced catalyst content, a higher degree of polymerization, a longer chain length, and relatively poor segment flexibility, and the polylactic acid polyol prepared using it has a relatively high indentation hardness.

[0100] In summary, the preparation method provided by the present invention has a high catalytic activity of the catalytic system and a high preparation yield; and the polylactic acid polyol provided by the embodiment of the present invention has a flexible chain segment, which can provide a suitable degree of crosslinking when used to prepare a polyurethane material, and the prepared polyurethane material has a small indentation hardness and good flexibility. In addition, the production cost of the existing polylactic acid polyol is 50 to 70 yuan / kg, and the production cost of the polylactic acid polyol of the present invention is 40 to 60 yuan / kg. It can be seen that the method of the present invention greatly reduces the preparation cost of polylactic acid polyol.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing polylactic acid polyol, characterized in that: The following steps are involved: Step 1, preparing an in-situ catalyst by heating a zinc salt, an organic ammonium salt and bis(ethylene carbonate) ether; the anion of the organic ammonium salt is selected from any one of bromide ion, chloride ion and iodide ion; Step 2: adding lactide monomer to obtain the polylactic acid polyol through polymerization reaction.

2. The preparation method according to claim 1, characterized in that: The zinc salt is selected from at least one of zinc chloride and zinc bromide; the organic ammonium salt is selected from at least one of tetrabutylammonium chloride, tetrabutylammonium bromide and tetrabutylammonium iodide compounds.

3. The preparation method according to claim 1, characterized in that: The structural formula of the bis(ethylene carbonate) ether is: Preferably, the mass ratio of the zinc salt, the organic ammonium salt and the bis(ethylene carbonate) ether is 1:10-50:30-50; Preferably, in step 1, the temperature of the heating reaction is 180-220° C., and the time of the heating reaction is 1-3 h.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the bis(ethylene carbonate) ether in step 1 to the lactide monomer in step 2 is 1:30-60; Preferably, in step 2, the polymerization reaction temperature is 130-180° C. and the time is 1-2 hours.

5. The polylactic acid polyol obtained by the preparation method described in any one of claims 1 to 4.

6. The polylactic acid polyol according to claim 5, characterized in that The general structural formula of the polylactic acid polyol is shown in formula (1): In formula (1), m is 3 to 20, n is 3 to 20, and X is a halogen atom.

7. The polylactic acid polyol according to claim 6, characterized in that The halogen atom is selected from any one of bromine, chlorine and iodine.

8. Use of the polylactic acid polyol according to claim 5 in the preparation of polyurethane materials.

9. A polyurethane material prepared from the polylactic acid polyol according to claim 5, characterized in that: The preparation comprises the following steps: The polyurethane material is obtained by reacting the polylactic acid polyol and polyisocyanate under the action of a catalyst.

10. The polylactic acid polyol according to claim 9, characterized in that The polyisocyanate is selected from at least one of toluene diisocyanate and diphenylmethane diisocyanate; Preferably, the catalyst is a tin catalyst; Preferably, the reaction time is 1 to 2 hours; Preferably, the mass ratio of the polylactic acid polyol to the polyisocyanate is 28-65:100.

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