SOLVENT-FREE ADHESION-PROMOTING CHAIN EXTENDER, PREPARATION METHOD THEREFOR, AND APPLICATION THEREOF

Abstract

A solvent-free adhesion-promoting chain extender, a preparation method therefor, and an application thereof are disclosed. The method includes the following steps: mixing an aromatic vinyl monomer, an acrylate-based monomer, an initiator, and water, then heating the mixture for polymerization, and subjecting the product to a secondary reaction by a twin-screen extruder for granulation, to prepare the extender. The obtained epoxy functionalized chain extender can be applied to a recycled material of a polyester structure and can be used for the repair and growth of molecular chains of biobased and biodegradable plastics of a polyester structure. The method features no use of a solvent in a process route, low investment, easily available apparatuses, low emission in the process route, and simple process control; in addition, the product has stable composition and is easy to use, and thus can be widely used, such as medical treatment, packaging, home appliances, automobiles, and aviation.

Claims

1. A solvent-free adhesion-promoting chain extender, wherein the solvent-free adhesion-promoting chain extender is prepared by a method comprising the following steps: mixing an aromatic vinyl monomer, an acrylate monomer, an initiator, a molecular weight regulator and water, heating and polymerizing to prepare the solvent-free adhesion-promoting chain extender; when a mass percentage of the aromatic vinyl monomer and the acrylate monomer is 100%, a mass percentage of the aromatic vinyl monomer is 76-99%

2. The solvent-free adhesion-promoting chain extender according to claim 1, wherein when a mass percentage of the aromatic vinyl monomer and the acrylate monomer is 100%, a mass percentage of the aromatic vinyl monomer is 80-95%; an amount of the initiator is 0.1-2% of the mass of the aromatic vinyl monomer; and a weight average molecular weight of the solvent-free adhesion-promoting chain extender is 30,000-150,000.

3. The solvent-free adhesion-promoting chain extender according to claim 2, wherein the amount of the initiator is 0.1-1% of the mass of the aromatic vinyl monomer; and the weight average molecular weight of the solvent-free adhesion-promoting chain extender is 50,000-100,000.

4. The solvent-free adhesion-promoting chain extender according to claim 1, wherein the adhesion-promoting chain extender has a multi-branched structure, and a functional group having a reactivity is located on a side chain thereof.

5. The solvent-free adhesion-promoting chain extender according to claim 1, wherein a temperature of the heating and polymerizing is 65-110° C., and a reaction time is 2-10 hours.

6. The solvent-free adhesion-promoting chain extender according to claim 5, wherein the heating and polymerizing is performed at 65-80° C. for 2-6 hours, and then at 90-110° C. for 0.5-2 hours.

7. The solvent-free adhesion-promoting chain extender according to claim 1, wherein after the heating and polymerizing is completed, the solvent-free adhesion-promoting chain extender is subjected to a double-screw secondary reaction granulation.

8. (canceled)

9. A method for preparing a chain-extended polyester polymer, comprising the following steps: mixing an aromatic vinyl monomer, an acrylate monomer, an initiator, a molecular weight regulator and water, heating and polymerizing to prepare a solvent-free adhesion-promoting chain extender; mixing a polyester polymer raw material and the solvent-free adhesion-promoting chain extender, and extruding to obtain the chain-extended polyester polymer; and when a mass percentage of the aromatic vinyl monomer and the acrylate monomer is 100%, a mass percentage of the aromatic vinyl monomer is 76-99%.

10. The method according to claim 9, wherein an amount of the solvent-free adhesion-promoting chain extender is 0.5-2% of an amount of the polyester polymer raw material.

11. A method for preparing a solvent-free adhesion-promoting chain extender, comprising the following steps: mixing an aromatic vinyl monomer, an acrylate monomer, an initiator, a molecular weight regulator and water, heating and polymerizing to prepare the solvent-free adhesion-promoting chain extender; when a mass percentage of the aromatic vinyl monomer and the acrylate monomer is 100%, a mass percentage of the aromatic vinyl monomer is 76-99%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects, and advantages of the present invention will become more apparent upon implementing the detailed description of non-limiting embodiments with reference to the following drawings.

[0025] FIG. 1 is a TGA analysis comparison between Example 1 and Example 2.

[0026] FIG. 2 is a capillary rheological data comparison of Example 1 and Comparative Example 6 at 250° C. and 270° C.

EMBODIMENT OF THE INVENTION

[0027] The present invention will be described in detail below with reference to specific embodiments. The following examples will be helpful for a person skilled in the art to further understand the invention, but do not limit the invention in any form. It should be noted that a person of ordinary skill in the art can make several variations and improvements without departing from the concept of the present invention. These are all within the protection scope of the present invention.

[0028] The preparation method of the solvent-free adhesion-promoting chain extender includes the following steps: putting an aromatic vinyl monomer, an acrylate monomer, an initiator, a molecular weight regulator and water into a reaction kettle, reacting at 65-80° C. under stirring for 2-8 hours, continuously reacting at 90-110° C. for 0.5-2 hours, discharging, filtering and drying to obtain the solvent-free adhesion-promoting chain extender; and carrying out secondary reaction granulation on the double-screw rod to obtain the solvent-free adhesion-promoting chain extender The preparation process does not need an organic solvent, does not need to be pressurized, and does not need special atmosphere protection.

[0029] The preparation method of the chain extender polyester polymer includes the following steps: mixing an aromatic vinyl monomer, an acrylate monomer, an initiator, a molecular weight regulator and water, heating and polymerizing to prepare a solvent-free adhesion-promoting chain extender; and mixing the polyester polymer raw material, the solvent-free adhesion-promoting chain extender and extruding to obtain a chain extender polyester polymer. Preferably, the amount of the solvent-free adhesion-promoting chain extender is 0.5-2% of the mass of the polyester polymer raw material. The polymer raw material can be pure particles or recycled plastic; can be applied to recycled polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and other polyester recycled materials, and can be applied to repair and growth of unused bio-based and biodegradable plastic molecular chains such as polylactic acid (PLA), butylene adipate and butylene terephthalate (PBAT), polypropylene carbonate (PPC) and the like.

[0030] Test conditions are as follows

[0031] The weight average molecular weight (Mw): using PS as a standard sample, adopting GPC test; RTVM: testing according to ASTM D790 standard and adopting GC-MS.

[0032] The terminal carboxyl concentration is tested according to GB/T-14190-2008 and acid-base titration

[0033] The melt index is tested according to ASTM D 1238 standard, and the test condition is 270° C.*2.16 Kg.

[0034] The intrinsic viscosity is tested according to the standard of GB/T-14190-2008.

[0035] The crystallinity is tested according to ASTM E793 standard, and DSC testing is adopted.

[0036] The glass transition temperature/Tg test is tested according to ASTM E 1356-98 standard, and DSC test is used.

[0037] Thermal weight loss is carried out according to ASTM D 6370-99, and TGA is used.

[0038] The reaction activity is tested according to ASTM D1652 standard.

[0039] Functional group density: the number of epoxy functional groups per 1000 molecular weight length molecular chain is obtained by combining molecular weight and molecular weight distribution.

TABLE-US-00001 TABLE 1 Compositions of Examples and Comparative Examples, Mass Percentage Com Com Com Com Com Com Materials Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 7 Styrene 80 80 90 85 95 80 99 75 80 80 GMA 20 20 10 15  5 20  1 25 100    20 20 Initiator   0.4   0.4   0.8   0.6   0.9   0.4   0.4   0.4 0.4   0.4   0.4 NW regulator   0.7   0.7   0.1   0.3   0.1   0.7   0.7   0.7 0.7   0.7   0.7 Process  (1)  (2)  (1)  (1)  (1)  (3)  (2)  (2) (2)    (4)  (5)

[0040] Preparation process is as follows:

[0041] (1) Mixing styrene, glycidyl methacrylate GMA, an initiator azobisisobutyronitrile, a molecular weight regulator dodecyl mercaptan and 200 parts by mass of deionized water in a reaction kettle, reacting for 5 hours at 70° C. under conventional stirring, heating to 110° C., continuing to react for 2 hours, then discharging the obtained particles in a discharging groove, adding the obtained particles into a twin-screw extruder at 95° C., extruding and granulating at 190° C. to obtain the solvent-free adhesion-promoting chain extender. A long-diameter ratio of the twin-screw extruder is 35, and the double-screw extruder has multi-stage vacuum.

[0042] (2) Mixing styrene, GMA, initiator azobisisobutyronitrile, molecular weight regulator dodecyl mercaptan and 200 parts by mass of deionized water in a reaction kettle, reacting for 5 hours at 70° C. under conventional stirring, raising the temperature to 110° C., continuing to react for 2 hours, discharging in a discharging groove, carrying out conventional filtration, and drying the obtained particles at 95° C. to constant weight to obtain the solvent-free adhesion-promoting chain extender.

[0043] (3) Mixing styrene, GMA, an initiator azobisisobutyronitrile, a molecular weight regulator dodecyl mercaptan and 200 parts by mass of deionized water in a reaction kettle, reacting at 85° C. under conventional stirring for 7 hours, discharging the mixture in a discharging groove, carrying out conventional filtration, and drying the obtained particles at 95° C. to constant weight to obtain the solvent-free adhesion-promoting chain extender.

[0044] (4) Mixing styrene, GMA, initiator azobisisobutyronitrile, molecular weight regulator dodecyl mercaptan and 200 parts by mass of anhydrous toluene in a three-necked flask, reacting at 110° C. under conventional stirring for 5 hours, recovering a solvent, discharging, and drying the obtained particles at 95° C. to constant weight to obtain a solvent type adhesion-promoting chain extender.

[0045] (5) Mixing styrene, GMA, an initiator azobisisobutyronitrile and a molecular weight regulator dodecyl mercaptan into a three-necked bottle, vacuumizing, introducing nitrogen for protection, condensing under condensation at 80° C. for 2 hours, and reacting at 50° C. for 12 hours to obtain a chain extender.

[0046] The present application discloses that styrene and GMA are copolymerized to synthesize ST-GMA. The GMA group can preferentially react with the end group of the polyester material, especially the small molecule group generated by the degradation reaction is reacted, so that the effect of repairing the molecular chain is achieved, so that the material has good adhesion and chain extension effects on the returned polyester or the degradable polymer. Meanwhile, the mechanical property of the material can be improved; and in addition, the degradable polymer can also play a role in controlling the degradation speed. According to the conventional test conditions, the molecular weight (Mw) and residual monomer content (RTVM) of the control chain extender are tested according to the conventional test conditions, and the test results are shown in Table 2. The adhesion-promoting chain extender has high reaction activity and high Tg, wherein the epoxy functional group with the reactivity is located on the side chain, the intrinsic viscosity of the polyester material can be effectively improved, the end group concentration is reduced, and the fusion finger is reduced; and meanwhile, due to the molecular structure of the chain extender, the Tg and the crystallinity of the polyester material are also helped.

TABLE-US-00002 TABLE 2 Molecular Weight and Residual Monomer of Examples and Comparative Examples Com Com Com Com Com Com Materials Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 7 Nw/10,000 8 8 8.5 8 7.8 1 12 5   0.1 7.8 2.5 Functional 0.75 0.74 0.73 0.76 0.72 0.65 0.37 0.61 / 0.73 0.53 Group Density Reactivity/% 96 91 95 98 93 84 74 78 14 82 80 RTVM (styrene/ 700 3670 820 720 790 4356 4710 3986 / 4000 4898 ppm) RTVM (GMA/ 1000 3460 580 680 410 4080 1258 5380 5200  4231 5087 ppm) Tg/° C. 94 94 93 95 92 86 70 82 / 85 83

[0047] Examples 1-5 are compared to Comparative Examples 1-5, commercially available BASF ADR 4370 (Comparative example 6), and Comparative Example 7 as chain extender and recycled PET at 240° C., respectively, and pelletized by a high vacuum twin screw. Specifically, the chain extender and the recycled PET are added into a twin-screw extruder (the amount of the chain extender is 1% of the mass of recycled PET), and granulation is performed on the double-screw rod under the condition of 240° C. to obtain polymer particles; and the particle test end group concentration, the melt index (MI), the crystallinity, the glass transition temperature and the test result are shown in Table 3. The extrusion result shows that the comparative example has the phenomena of charging port aggregate, melt pressure change, strip breakage and the like, and are stable in melt pressure, few in feeding port and free of gel phenomenon when the chain extender is used for granulation. The chain extender of the present invention has a plurality of reactive functional groups on a single molecular chain, the reaction activity is high, the end group concentration of the material can be remarkably reduced, or the material can be degraded, and the thermal stability and viscosity of the material are improved.

TABLE-US-00003 TABLE 3 Comparison of the liquidity and appearance of the chain extension effect of examples and comparative examples on the recovery of PET Terminal carboxyl Melt Index (MI) Crystallinity Glass transition Viscosity Items Mmol/Kg 270° C. * 2.16 Kg % temperature ° C. dL/g Recycled PET 31.1 156.78 22.55 80.46 0.584 New PET 25.2 74.68 24.82 81.34 0.642 Example 1 13.7 39.6 24.88 83.38 0.907 Example 2 15.87 52.7 23.48 81.99 0.705 Example 3 16.7 47.3 26.43 82.32 0.878 Example 4 12.82 41.2 26.73 83.86 0.910 Example 5 17.7 58.6 25.24 83.22 0.866 Com. Ex. 1 22.7 68.6 23.24 80.12 0.686 Com. Ex. 2 22.0 20.7 25.30 81.16 0.548 Com. Ex. 3 22.8 76.7 25.52 81.27 0.622 Com. Ex. 4 13.2 94.68 22.90 76.40 0.536 Com. Ex. 5 19.98 65.7 23.18 80.67 0.623 Com. Ex. 6 14.2 30.5 23.55 81.73 0.751 Com. Ex. 7 19.76 65.4 22.38 80.52 0.619

[0048] As shown in Table 2, the molecular weight of the chain extender is close to the density of the functional groups when comparing example 1 with comparative example 5 and comparative example 7, but the difference of the reaction activity measurement data is large, and the process is combined with the RTVM test result.

[0049] The obtained chain extender is more complete in reaction degree, has the advantages that the reaction activity is greatly improved, and as shown in FIG. 1, the thermal stability of the chain extender is improved, and later processing and downstream use are facilitated. The chain extension effect of the sample of Comparative Example 5 and Comparative example 7 is also significantly less than that of Example 1. This is because the residual GMA of the small molecule will preferentially react with the end group of the polyester. Although the end group concentration of the return polyester is decreased, the reaction does not increase the viscosity.

[0050] As shown in Table 1 to Table 3, the chain extender has a relationship with a molecular weight, a GMA concentration, a residual monomer amount of GMA, a reaction condition, etc. Although the content of GMA is the same as that in Comparative Example 1, the content of GMA is different, and the difference of functional groups density is different, thereby affecting the reaction activity. The chain extension effect of Examples 1-2 is more obvious, and the terminal carboxyl concentration is lower. Tt can be seen that the appropriate molecular weight facilitates the chain extension reaction.

[0051] The content of GMA is different. For example, the density of GMA is too low, the density of GMA is low, the reaction activity is low, the chain extension effect is poor, as the content of GMA is increased, the chain extension effect is poor, but not linear growth, the appropriate GMA density is more important (as in Example 1 and Example 4), the chain extension effect of Example 4 is further superior to that of Example 1. When the GMA content is too high (as for Example 3 and 4), the effect is negative.

[0052] In combination with the data of FIG. 2 and Table 1 to Table 3, compared with Comparative Example 6, the terminal carboxyl concentration and MI of the Example 1 are relatively close, but the characteristic viscosity increase of the Example 1 is more obvious, and the combined crystallinity and the glass transition temperature are also more advantageous, which has a certain relationship with the own molecular weight of the Example 1. In particular, the glass transition temperature of the recycled PET with the chain extender of the comparative example 6 is obviously low. It can be seen that the design of the molecular structure of the chain extender also influences the production of the recycled polyester and the degradable polyester.

[0053] In FIG. 2, the viscosity of the same type of degradable polyester material is observed in the capillary rheometer in a direct blending manner, and analysis is performed. Under the condition of 250° C., the shear viscosity of Example 1 and Comparative Example 6 is close, but the shear viscosity of Comparative Example 6 is significantly reduced when the processing temperature is raised to 270° C.

[0054] The specific embodiments of the present invention are described above. It should be understood that the present invention is not limited to the specific embodiments described above, and various changes or modifications can be made by a person skilled in the art within the scope of the claims, which does not affect the essence of the present invention.

[0055] Compared with the prior art, the chain extender has the following beneficial effects: 1, The chain extender has high molecular weight and a plurality of reactive functional groups on a single molecular chain. The functional groups do not interfere with each other, and have high reaction activity. The chain extender significantly reduces the end-group concentration, improves the viscosity of the material, and is not prone to forming gel. 2, The reaction process is controllable, the reaction activity is high, the thermal stability is good, and makes it easy to obtain material with high intrinsic viscosity and high melt strength. 3, The process route does not need to use solvent, the investment is small, the equipment and the raw materials are easy to obtain, the process step is few, the mass ratio is simple, and the obtained composition is stable. 4, The chain extender disclosed by the invention has high molecular weight, is thermally stable, has a high softening point and is easy to feed. It is suitable for various processing technologies and conditions, and avoids the problem of softening and caking problems or equipment selectivity in the production process. 5, The monomer has the characteristics of no toxicity or low toxicity, the raw material monomer is easy to obtain, the process route can further improve the degree of polymerization, and the residual order is reduced. The method is suitable for high-end application related to medical instruments and food medicine packaging.

[0056] According to the invention, the technical progress and the green production of the technical field of the leading collar can be smoothly implemented, the supporting capability and the innovation capability of the circulating economic technology are improved, and a positive pushing effect is achieved in the development of fine refining and high-added-value direction development in the chemical industry. Meanwhile, the technical scheme of the invention is a synthetic line capable of realizing industrial production, environmental protection and high yield.