Chain extender with autocatalytic performance as well as preparation method and application thereof

Abstract

The invention provides a chain extender with autocatalytic performance and a preparation method and application thereof. The chain extender comprises an epoxy group and a tertiary amine group; the tertiary amine group has the effect of catalyzing the reaction of an epoxy group and an active hydrogen group, so that the chain extender has the effect of catalyzing the ring opening of the epoxy group, and can react with a high-molecular polymer in a short time (several minutes to dozens of minutes) to improve the molecular weight of the high-molecular polymer or enable the high-molecular polymer to generate a branched structure; or enabling two different types of high-molecular polymers to form a block copolymer through a chain extender so as to increase the compatibility.

Description

Technical Field

[0001] The invention belongs to the technical field of high molecular polymerization and relates to a chain extender with autocatalytic performance and a preparation method and application thereof. Background Art

[0002] Polymers such as polyesters, polyamides, polycarbonates, and polyurethanes are widely used to manufacture plastic products such as films, bottles, and foams. The mechanical, physical, and foaming properties of these polymers are highly dependent on their molecular weight, molecular weight distribution, and branching structure. Processing these polymers into profiles, sheets, films, or fibers typically involves compounding, extrusion, and then injection molding or other methods of molding in a high-temperature molten state.

[0003] In recent years, with increasing demands for resource recycling and environmental protection, the recycling and regeneration steps involve high-temperature operations. However, during these high-temperature operations, the molecular weight of the polymer decreases to some extent, typically through high-temperature hydrolysis or alcoholysis. Studies have found that this molecular weight decrease negatively impacts the mechanical, thermal, and rheological properties of the polymer. For example, due to this molecular weight decrease, polyethylene terephthalate (PET) obtained from recycled bottle waste can only be used in fibers and other low-end applications; and polycarbonate obtained from recycled compact disc (CD) waste is primarily used in low-end applications. In other words, the reduction in molecular weight significantly reduces the application range of the recycled polymer.

[0004] In addition, under the demand for lightweight materials, foaming materials are used more and more. During the foaming process, the polymer needs to have high melt strength to better support the growth of bubbles and reduce bubble rupture, collapse and other phenomena. The melt strength of the polymer is closely related to the branched structure; however, the condensation reaction can generally only produce linear polymer materials, and cannot produce polymers with branched structures.

[0005] In recent years, the research on environmentally friendly materials has gradually increased, among which polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are two common biodegradable materials. PLA has good biological source and can be completely biodegraded, but its brittleness and slow biodegradation rate limit its application in packaging materials, disposable plastic products and films. PBAT has good toughness and fast biodegradation rate, but its low strength and poor gloss limit its application. If PLA and PBAT are compounded, the advantages of the two can be complementary. However, due to the large difference in solubility between PLA and PBAT, the two are typical incompatible systems, which leads to poor performance of the PLA and PBAT blend prepared by simple melt blending. In order to improve the comprehensive performance of the PLA and PBAT blend, a chain extender is usually introduced during the blending process to reduce the interfacial tension between the two phases of PLA and PBAT, improve the adhesion of the interface, and thus achieve the purpose of improving the compatibility of the two-phase system.

[0006] The chain extender reported so far is mainly a polymer containing epoxy groups. During the melt processing of the polymer, multiple epoxy groups on the molecular chain of the chain extender can react with -OH, -NHR (R is hydrogen or an organic group), -COOH and other groups containing active hydrogen on the end group of the high molecular polymer to increase the molecular weight, produce branching or form a block copolymer through the chain extender to increase the compatibility of two different kinds of polymers. However, due to the short time of melt processing, usually a few minutes to tens of minutes, only a small part of the epoxy groups on the molecular chain of the chain extender can participate in the reaction, which makes it difficult to increase the molecular weight of the polymer, produce branching of the polymer or form a block copolymer through the chain extender to increase the compatibility of two different kinds of polymers. SUMMARY

[0007] In order to promote the reaction of the epoxy groups on the molecular chain of the chain extender with the end group of the polymer, fully play the role of the chain extender (increase the molecular weight of the high molecular polymer, produce branching structure of the high molecular polymer, or form a block copolymer through the chain extender to increase the compatibility of two different kinds of high molecular polymers), while reducing the amount of chain extender and production cost, the present application provides a chain extender with self-catalytic performance and its preparation method and application. The chain extender comprises epoxy groups and tertiary amine groups. The tertiary amine groups have the function of catalyzing the reaction of epoxy groups and active hydrogen groups, which enables the chain extender to have the function of catalyzing the ring opening of epoxy groups, and can react with high molecular polymers in a short time (a few minutes to tens of minutes) to increase the molecular weight of high molecular polymers, produce branching structure of high molecular polymers, or form a block copolymer through the chain extender to increase the compatibility of two different kinds of high molecular polymers.

[0008] The object of the present application is achieved by the following technical solutions:

[0009] A chain extender with self-catalytic performance, the chain extender comprising at least one copolymer; the polymerized monomers of the copolymer comprising an (alkyl) acrylate polymerized monomer containing an epoxy group, an (alkyl) acrylate polymerized monomer containing a tertiary amine group, and a styrene polymerized monomer.

[0010] According to an embodiment of the present application, the polymerized monomers of the copolymer further comprise an (alkyl) acrylate polymerized monomer.

[0011] <An (alkyl) acrylate polymerized monomer containing an epoxy group>

[0012] According to an embodiment of the present application, the (alkyl) acrylate polymerized monomer containing an epoxy group comprises at least one of glycidyl acrylate and glycidyl methacrylate.

[0013] According to an embodiment of the present application, the (alkyl) acrylate polymerized monomer containing an epoxy group can introduce an epoxy group in the chain extender, the introduction of the epoxy group can react with a high molecular polymer containing a terminal group with active hydrogen, thereby increasing the molecular weight of the high molecular polymer, or making the high molecular polymer have a branched structure, or making two different kinds of high molecular polymers form a block copolymer through the chain extender to increase the compatibility.

[0014] <An (alkyl) acrylate polymerized monomer containing a tertiary amine group>

[0015] According to an embodiment of the present application, the (alkyl) acrylate polymerized monomer containing a tertiary amine group comprises at least one of dimethylaminoethyl acrylate, diethylaminoethyl acrylate, diisopropylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diisopropylaminoethyl methacrylate. Preferably, it is at least one of dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate.

[0016] According to an embodiment of the present application, the (alkyl) acrylate polymerized monomer containing a tertiary amine group can introduce a tertiary amine group in the chain extender, the introduction of the tertiary amine group can catalyze the ring-opening reaction of the epoxy group, i.e. catalyze the reaction of the epoxy group with a high molecular polymer containing a terminal group with active hydrogen, thereby increasing the molecular weight of the high molecular polymer, or making the high molecular polymer have a branched structure, or making two different kinds of high molecular polymers form a block copolymer through the chain extender to increase the compatibility.

[0017]

[0018] According to embodiments of the present application, the styrenic polymeric monomer includes at least one of styrene, methylstyrene, t-butylstyrene, and o-chlorostyrene. Preferably, styrene.

[0019] According to embodiments of the present application, the styrenic polymeric monomer is used to adjust the compatibility of the chain extender in the polymer.

[0020] <(Alkyl)acrylate polymeric monomer>

[0021] According to embodiments of the present application, the (alkyl)acrylate polymeric monomer includes at least one of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, sec-butyl acrylate, isobutyl acrylate, t-butyl acrylate, amyl acrylate, isoamyl acrylate, isobornyl acrylate, hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, amyl methacrylate, hexyl methacrylate, isoamyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, crotyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, and isobornyl methacrylate. Preferably, at least one of methyl acrylate, butyl acrylate, methyl methacrylate, and butyl methacrylate.

[0022] According to embodiments of the present application, the (alkyl)acrylate polymeric monomer is used to adjust the compatibility of the chain extender in the polymer.

[0023] <Chain extender>

[0024] According to an embodiment of the present invention, the mass of the (alkyl) acrylate polymerization monomer containing an epoxy group accounts for 20wt%-45wt% of the total mass of all polymerization monomers, for example, 20wt%, 25wt%, 30wt%, 35wt%, 40wt% or 45wt%; the mass of the (alkyl) acrylate polymerization monomer containing a tertiary amine group accounts for 5wt%-20wt% of the total mass of all polymerization monomers, for example, 5wt%, 10wt%, 15wt% or 20wt%; the mass of the styrene polymerization monomer accounts for 50wt%-75wt% of the total mass of all polymerization monomers, for example, 50wt%, 55wt%, 60wt%, 65wt%, 70wt% or 75wt%; the (alkyl) acrylate polymerization monomer accounts for 0wt%-30wt% of the total mass of all polymerization monomers, for example, 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%.

[0025] According to an embodiment of the present invention, the weight average molecular weight Mw of the chain extender is 5,000-100,000 g / mol, preferably 5,000-50,000 g / mol, for example 5,000 g / mol, 6,000 g / mol, 7,000 g / mol, 8,000 g / mol, 9,000 g / mol, 10,000 g / mol, 12,000 g / mol, 15,000 g / mol, 18,000 g / mol , 20,000g / mol, 22,000g / mol, 25,000g / mol, 28,000g / mol, 30,000g / mol, 35,000g / mol, 40,000g / mol, 45,000g / mol, 50,000g / mol, 60,000g / mol, 70,000g / mol, 80,000g / mol, 90,000g / mol or 100,000g / mol.

[0026] According to an embodiment of the present invention, the molecular weight distribution PDI of the chain extender is 1.5-5, preferably 2-3.5, for example, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5.

[0027] According to an embodiment of the present invention, the chain extender has an epoxy equivalent weight of 2000-100 g / mol, preferably 1400-150 g / mol, and more preferably 500-150 g / mol, such as 500 g / mol, 450 g / mol, 400 g / mol, 350 g / mol, 300 g / mol, 250 g / mol, 200 g / mol, or 150 g / mol. The epoxy equivalent weight refers to the mass of the chain extender containing 1 mol of epoxy groups.

[0028] Chain Extender

[0029] The present application also provides a chain extender comprising at least one copolymer; the copolymer comprising repeating units of Formula 1, repeating units of Formula 2, and repeating units of Formula 3:

[0030]

[0031] In Formula 1, R1is selected from C 1-6 alkyl or H; * is a point of attachment;

[0032] In Formula 2, R2is selected from C 1-6 alkyl or H; R3is selected from C 1-12 alkylene; R4and R5are the same or different and are independently selected from substituted or unsubstituted C 1-12 alkyl; if substituted, the substituents are halogen or C 1-12 alkyl; * is a point of attachment;

[0033] In Formula 3, R6is selected from C 1-6 alkyl or H; R7, R8, R9, R 10 and R 11 are the same or different and are independently selected from halogen, substituted or unsubstituted C 1-12 alkyl; if substituted, the substituents are halogen or C 1-12 alkyl; * is a point of attachment.

[0034] According to embodiments of the present application, in Formula 1, R1is selected from C 1-5 alkyl or hydrogen. Preferably, in Formula 1, R1is selected from C 1-4 alkyl or hydrogen. Also preferably, in Formula 1, R1is selected from C 1-3 alkyl or hydrogen. Further preferably, in Formula 1, R1is selected from C 1-2 alkyl or hydrogen.

[0035] According to embodiments of the present application, in Formula 2, R2is selected from C 1-4 alkyl or H; R3is selected from C 1-6 alkylene; R4and R5are the same or different and are independently selected from substituted or unsubstituted C 1-6 alkyl; if substituted, the substituents are halogen or C 1-6 alkyl. Preferably, in Formula 2, R2is selected from C 1-3 alkyl or H; R3is selected from C 1-3 alkylene; R4and R5are the same or different and are independently selected from substituted or unsubstituted C 1-3 alkyl; if substituted, the substituents are halogen or C 1-3 alkyl. Also preferably, in Formula 2, R2is selected from C 1-2 alkyl or H; R3is selected from C1-2 Alkylene; R4 and R5 are the same or different and are independently selected from substituted or unsubstituted C 1-2 Alkyl; if substituted, the substituent is halogen or C 1-2 alkyl.

[0036] According to an embodiment of the present invention, in Formula 3, R6 is selected from C 1-4 Alkyl or H; R7, R8, R9, R 10 and R 11 the same or different, independently selected from halogen, substituted or unsubstituted C 1-6 Alkyl; if substituted, the substituent is halogen or C 1-6 Preferably, in formula 3, R6 is selected from C 1-3 Alkyl or H; R7, R8, R9, R 10 and R 11 the same or different, independently selected from halogen, substituted or unsubstituted C 1-3 Alkyl; if substituted, the substituent is halogen or C 1-3 Also preferably, in formula 3, R6 is selected from C 1-2 Alkyl or H; R7, R8, R9, R 10 and R 11 the same or different, independently selected from halogen, substituted or unsubstituted C 1-2 Alkyl; if substituted, the substituent is halogen or C 1-2 alkyl.

[0037] According to an embodiment of the present invention, the copolymer further comprises a repeating unit represented by Formula 4:

[0038]

[0039] In formula 4, R 12 Selected from C 1-6 Alkyl or H; R 13 Selected from C 1-40 Aliphatic group or C 3-40 Alicyclic group; * is the connecting end.

[0040] According to an embodiment of the present invention, in Formula 4, R 12 Selected from C 1-5 Alkyl or H; R 13 Selected from C 1-30 Aliphatic group or C 3-30 Preferably, in Formula 4, R 12 Selected from C 1-4 Alkyl or H; R 13 Selected from C 1-20 Aliphatic group or C 3-20 Also preferably, in Formula 4, R12 selected from C 1-3 alkyl or H; R 13 selected from C 1-12 aliphatic group or C 3-12 cycloaliphatic group.

[0041] According to an embodiment of the present application, the mass of the repeating unit of formula 1 accounts for 20wt%-45wt% of the total mass of the copolymer, for example 20wt%, 25wt%, 30wt%, 35wt%, 40wt% or 45wt%; the mass of the repeating unit of formula 2 accounts for 5wt%-20wt% of the total mass of the copolymer, for example 5wt%, 10wt%, 15wt% or 20wt%; the mass of the repeating unit of formula 3 accounts for 50wt%-75wt% of the total mass of the copolymer, for example 50wt%, 55wt%, 60wt%, 65wt%, 70wt% or 75wt%; the mass of the repeating unit of formula 4 accounts for 0wt%-30wt% of the total mass of the copolymer, for example 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%.

[0042] According to an embodiment of the present application, the chain extender comprises at least one copolymer; the copolymer has a structural formula as shown in the following formula i:

[0043]

[0044] wherein R1-R 11 are defined as above, a, b and c are the polymerization degrees of the three repeating units constituting the copolymer, and a+b+c=1.

[0045] According to an embodiment of the present application, the chain extender comprises at least one copolymer; the copolymer has a structural formula as shown in the following formula ii:

[0046]

[0047] wherein R1-R 13 are defined as above, a, b, c and d are the polymerization degrees of the four repeating units constituting the copolymer, and a+b+c+d=1.

[0048] <Method for preparing chain extender>

[0049] The present application also provides a method for preparing the chain extender as described above, which comprises the following steps:

[0050] The (alkyl) acrylate polymer monomer containing a tertiary amine group, the styrene polymer monomer, the (alkyl) acrylate polymer monomer, the solvent and the free radical initiator are added into a reaction kettle, the reaction kettle is deoxygenated under vacuum, then inert gas is filled, and the polymerization reaction is initiated by heating. After the polymerization reaction is completed, the solvent and the unreacted polymer monomer in the reaction system are removed, and the chain extender is prepared.

[0051] According to an embodiment of the present application, the solvent is selected from aromatic hydrocarbons, alkanes or ester organic solvents; and exemplarily, the solvent includes at least one of xylene, toluene, ethylbenzene, ethyl acetate, propyl acetate and butyl acetate.

[0052] According to an embodiment of the present application, the solvent is added in an amount of 0.5-5 times, preferably 0.5-2 times, such as 0.5 times, 1 times, 1.5 times or 2 times, of the total mass of the polymer monomers.

[0053] According to an embodiment of the present application, the free radical initiator is selected from free radical initiators having a half-life period of about 1 hour at a temperature higher than or equal to 90℃; and exemplarily, the free radical initiator includes at least one of 1-tert-amylazo-1-cyanocyclohexane, azobisisobutyronitrile, 2,2,-azo-bis(2-methyl)butyronitrile, tert-butyl peroctoate, tert-butyl perbenzoate, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-amyl peroxide and tert-butyl peroxy-2-ethylhexanoate.

[0054] According to an embodiment of the present application, 0.0005-0.06 moles of the free radical initiator are added per 1 mole of the polymer monomers, including the (alkyl) acrylate polymer monomer containing an epoxy group, the (alkyl) acrylate polymer monomer containing a tertiary amine group, the styrene polymer monomer and the (alkyl) acrylate polymer monomer.

[0055] According to an embodiment of the present application, the temperature of the polymerization reaction is 60-180℃, preferably 80-150℃, such as 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃; and the time of the polymerization reaction is 1-15h, preferably 1-6h, such as 2h, 3h, 4h or 5h.

[0056] According to an embodiment of the present application, after the polymerization reaction is completed, the polymerization system can be heated to 150℃ or above, and the solvent and the unreacted polymer monomer are removed under vacuum until the content of the residual monomer and the solvent in the polymer is less than 0.1wt%. After the unreacted polymer monomer and the solvent are removed, the polymer can be pelletized by a screw to prepare the chain extender in the form of particles, which is convenient for use.

[0057] According to the embodiments of the present application, after the polymerization reaction, the polymer can be precipitated by adding an alcohol solvent, such as methanol or ethanol, into the polymerization system by cooling, and the unreacted polymerization monomer and solvent can be removed by washing, and the chain extender in the form of granules can be obtained by screw granulation, which is convenient for use.

[0058] <Applications of the chain extender>

[0059] The present application also provides applications of the chain extender described above, which is used for chain extension of a high molecular polymer containing active hydrogen at the end group.

[0060] According to the embodiments of the present application, the chain extender is used for recycling, branching modification and blending modification of a high molecular polymer containing active hydrogen at the end group.

[0061] According to the embodiments of the present application, the high molecular polymer containing active hydrogen at the end group includes at least one of polyester (including polylactic acid (PLA)), polyamide (PA), polycarbonate (PC), polyurethane (PU), polyacetal, polysulfone, polyphenylene ether (PPE), polyether sulfone, polyimide, polyetherimide, polyether ketone, polyether ether ketone, polyaryletherketone or polyphenylene sulfide.

[0062] The present application also provides a composition including the chain extender described above and a high molecular polymer containing active hydrogen at the end group.

[0063] According to the embodiments of the present application, the mass of the chain extender accounts for 0.5-5 wt% of the total mass of the composition, for example, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt% or 5 wt%.

[0064] <Method for recycling a high molecular polymer>

[0065] The present application also provides a method for recycling a high molecular polymer, which includes the following steps:

[0066] The high molecular polymer containing active hydrogen at the end group and the chain extender described above are mixed, and melt extrusion granulation is performed by an extruder to achieve recycling of the high molecular polymer.

[0067] According to the embodiments of the present application, the mass ratio of the high molecular polymer containing active hydrogen at the end group and the chain extender is 95-99.5:5-0.5; for example, 95:5, 95.5:4.5, 96:4, 96.5:3.5, 97:3, 97.5:2.5, 98:2, 99:1 or 99.5:0.5.

[0068] According to embodiments of the present application, the temperature of the melt extrusion granulation is 130-180°C; the time of the melt extrusion granulation is 5-20 min, such as 8 min, 10 min, 12 min, 15 min, or 18 min.

[0069] <Method for branched modification of high molecular polymer>

[0070] The present application also provides a method for branched modification of high molecular polymer, which comprises the following steps:

[0071] The high molecular polymer with active hydrogen at end groups and the chain extender are mixed, and melt extrusion granulation is performed by an extruder to achieve branched modification of the high molecular polymer.

[0072] According to embodiments of the present application, the mass ratio of the high molecular polymer with active hydrogen at end groups and the chain extender is 95-99.5:5-0.5; for example, 95:5, 95.5:4.5, 96:4, 96.5:3.5, 97:3, 97.5:2.5, 98:2, 99:1, or 99.5:0.5.

[0073] According to embodiments of the present application, the temperature of the melt extrusion granulation is 130-180°C; the time of the melt extrusion granulation is 5-20 min, such as 8 min, 10 min, 12 min, 15 min, or 18 min.

[0074] <Method for blended modification of high molecular polymer>

[0075] The present application also provides a method for blended modification of high molecular polymer, which comprises the following steps:

[0076] The high molecular polymer with active hydrogen at end groups and the chain extender are mixed, and melt extrusion granulation is performed by an extruder to achieve blended modification of the high molecular polymer.

[0077] According to embodiments of the present application, the mass ratio of the high molecular polymer with active hydrogen at end groups and the chain extender is 95-99.5:5-0.5; for example, 95:5, 95.5:4.5, 96:4, 96.5:3.5, 97:3, 97.5:2.5, 98:2, 99:1, or 99.5:0.5.

[0078] According to embodiments of the present application, the temperature of the melt extrusion granulation is 130-180°C; the time of the melt extrusion granulation is 5-20 min, such as 8 min, 10 min, 12 min, 15 min, or 18 min.

[0079] In the present invention, the term (alkyl) acrylate monomer may refer to an acrylate monomer or an alkyl acrylate monomer.

[0080] Beneficial effects of the present invention:

[0081] The present invention provides a chain extender with autocatalytic properties, a preparation method thereof, and an application thereof; the chain extender comprises an epoxy group and a tertiary amine group; the tertiary amine group has the function of catalyzing the reaction between the epoxy group and the active hydrogen group, so that the chain extender has the function of catalyzing the ring opening of the epoxy group. The chain extender can react with a high molecular weight polymer within a short time (several minutes to more than ten minutes) to increase the molecular weight of the high molecular weight polymer, or generate a branched structure in the high molecular weight polymer, or form a block copolymer of two different types of high molecular weight polymers through the chain extender to increase compatibility. DETAILED DESCRIPTION

[0082] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0083] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the reagents, materials, etc. used in the following examples are all commercially available unless otherwise specified.

[0084] The molecular weight and molecular weight distribution of the chain extender of the present invention are measured and calculated by GPC.

[0085] The epoxy equivalent of the chain extender of the present invention is measured and calculated according to GB / T 1677-2008 “Determination of Epoxy Value of Plasticizers”.

[0086] Examples 1-4 and Comparative Example 1: Preparation of Chain Extender

[0087] (1) Add xylene, styrene, methyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, and tert-butyl peroxy-2-ethylhexanoate to a 500 ml three-necked flask equipped with a thermometer and a condenser. Stir, evacuate to remove air, and fill with nitrogen. Repeat this process three times.

[0088] (2) The mixture was heated to 130°C and stirred at this temperature for 5 h to obtain a colorless viscous solution;

[0089] (3) After the reaction is completed, the reaction solution is added to a large amount of anhydrous ethanol for precipitation and washed with ethanol three times;

[0090] (4) The product was vacuum dried in a vacuum oven at 60°C for 6h, and became transparent solid after cooling;

[0091] (5) The transparent solid was granulated into granules by twin-screw, and the chain extender was obtained and ready for use.

[0092] The adding amount (unit: g) of each component (polymerization monomer, initiator and solvent) in the polymerization process of the chain extender prepared in Examples 1-4 and Comparative Example 1 is shown in Table 1, and the test results of the properties of the chain extender prepared are shown in Table 2.

[0093] Table 1 Adding amount (unit: g) of each component in the polymerization process of the chain extender prepared in Examples 1-4 and Comparative Example 1

[0094]

[0095] Table 2 Molecular weight, molecular weight distribution and epoxy equivalent of the chain extender prepared in Examples 1-4 and Comparative Example 1

[0096]

[0097] Examples 5-9: Chain extender used for PLA and PBAT blending

[0098] First, PLA and PBAT were dried in a forced air drying oven at 80°C for 12h, and 400g of PLA and PBAT, 200g of talcum powder, and 0, 0.25%, 0.5%, 0.75%, 1%, 1.25% of the chain extender (the chain extender prepared in Examples 1-4 and Comparative Example 1) by mass fraction of the total polymer mass (800g) were weighed and placed in a high-speed mixer to mix uniformly, and the obtained mixture was melted and extruded into granules in a co-rotating twin-screw extruder, the barrel temperature was 130°C, 150°C, 165°C, 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, and the screw rotation speed was 180r / min, the obtained granules were injected into standard bars in an injection molding machine, the shaft temperature of the injection molding machine was 175°C, 185°C, 185°C, and the modified polymer after blending was obtained, and the melt index of the modified polymer after blending was tested, and the results are shown in Table 3.

[0099] Table 3 Test results of the influence of the type and adding amount of the chain extender on the melt index of PBAT / PLA blend (unit: g / 10min)

[0100]

[0101] As can be seen from Table 3, compared with Examples 1-4, the chain extender of Comparative Example 1 has a smaller effect on reducing the melt index of the PLA and PBAT blend, because the chain extender of Comparative Example 1 does not contain a tertiary amine group, and the ring-opening reaction efficiency of the epoxy group is low; the chain extenders of Examples 1-4 contain a tertiary amine group, which can more efficiently catalyze the ring-opening reaction of the epoxy group and the end group of the polymer.

[0102] The mechanical properties of the blend obtained after adding the chain extender of Example 2 to the blend were tested, and the test results are shown in Table 4.

[0103] Table 4 Effect of addition amount of chain extender of Example 2 on mechanical properties of PBAT / PLA blend

[0104]

[0105] As can be seen from Table 4, with the addition of the chain extender, the mechanical properties of the obtained PBAT / PLA blend show a trend of first increasing and then decreasing, because the chain extender plays a good compatibilization effect.

[0106] Examples 10-14: Chain extender for PLA chain extension modification

[0107] First, the PLA was dried in a forced air drying oven at 80°C for 12h, the amount of PLA was 1000g, and the mass fraction of the chain extender was 0, 0.5%, 1.0%, 1.5%, 2%, and 2.5% of the mass of the polymer (1000g), respectively, which was placed in a high-speed mixer to mix uniformly, and the obtained mixture was melted and extruded into granules in a co-rotating twin-screw extruder, the barrel temperature was 130°C, 150°C, 165°C, 170°C, 180°C, 180°C, 180°C, 180°C, and 180°C, respectively, and the screw rotation speed was 350r / min, the obtained granules were injected into a standard sample bar in an injection molding machine, the shaft temperature of the injection molding machine was 175°C, 185°C, and 185°C, respectively, to obtain the chain extension modified polymer, and the melt index of the chain extension modified polymer was tested, and the results are shown in Table 5.

[0108] Table 5 Effect of type and addition amount of chain extender on melt index of chain extension modified PLA (unit: g / 10min)

[0109]

[0110] As can be seen from Table 5, compared with Examples 1-4, the chain extender of Comparative Example 1 has a smaller effect on reducing the melt index of PLA, because the chain extender of Comparative Example 1 does not contain a tertiary amine group, and the ring-opening reaction of the epoxy group is weak, that is, the content of the epoxy group actually participating in the reaction in the chain extender of Comparative Example 1 is small, and the effect of chain extension modification is poor; while the chain extenders of Examples 1-4 contain tertiary amine groups, which can more efficiently catalyze the ring-opening reaction of the epoxy group and the end group of the polymer.

[0111] The chain extender of Example 3 has a more uniform and regular polymer chain because the content of glycidyl methacrylate is reduced, which effectively improves the utilization rate of the chain extender, and thus has the best effect on reducing the melt index of PLA.

[0112] Table 6 Effect of different amounts of the chain extender of Example 3 on the mechanical properties of PLA

[0113]

[0114] Table 7 Effect of different amounts of the chain extender of Comparative Example 1 on the mechanical properties of PLA

[0115]

[0116] Table 6 and Table 7 are the data of the effect of different amounts of the chain extenders of Example 3 and Comparative Example 1 on the mechanical properties of PLA. As can be seen from the test results, compared with Example 3, Comparative Example 1 has a smaller effect on improving the impact strength of modified PLA, indicating that its effect on improving the toughness of PLA is not as good as that of Example 3. The improvement in other mechanical properties such as tensile strength, elongation at break and bending strength is also not as good as that of Example 3.

[0117] Examples 15-21: Exploration of the chemical foaming performance of the chain extender for PLA

[0118] First, the PLA was dried in a forced air drying oven at 80°C for 12h, and the PLA was 20g. The chain extender was 0.5%, 1%, 1.5%, 2.5% of the mass of the polymer (20g), and the chemical foaming agent was 5%. The mixture was mixed uniformly in a high-speed mixer, and the obtained mixture was mixed and kneaded in a torque rheometer, the barrel temperature was 180°C, and the screw rotation speed was 20r / min. The obtained granules were subjected to foaming experiment in an oven, and the foaming time was 15min. The foaming ratio of the PLA foaming sample is shown in Table 8.

[0119] Table 8 Specific test scheme and process conditions of foaming PLA sample

[0120]

[0121] From the test results of Examples 15-18 in Table 8, it can be seen that as the amount of chain extender added increases, the melt strength of polylactic acid PLA continues to increase, thereby better supporting the growth of bubbles and reducing phenomena such as bubble rupture and collapse. Therefore, the foaming ratio shows a trend of gradually increasing.

[0122] From the test results of Examples 18-21 in Table 8, it can be seen that with the increase of the foaming temperature, the foaming ratio of the polylactic acid foam material shows a trend of first increasing and then decreasing; this is because the foaming temperature changes the melt strength and viscosity of the polylactic acid. At a suitable foaming temperature, the polylactic acid foam material can obtain a higher foaming ratio, while if the temperature is too high or too low, the bubble size and distribution will become uneven.

[0123] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A chain extender having autocatalytic properties, wherein: The chain extender comprises at least one copolymer; the polymerization monomers of the copolymer comprise (alkyl) acrylate polymerization monomers containing epoxy groups, (alkyl) acrylate polymerization monomers containing tertiary amine groups and styrene polymerization monomers.

2. The chain extender according to claim 1, wherein The polymerization monomers of the copolymer further include (alkyl) acrylate polymerization monomers; The (alkyl) acrylate polymerization monomer includes at least one of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, pentyl acrylate, isopentyl acrylate, isobornyl acrylate, hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, pentyl methacrylate, hexyl methacrylate, isopentyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, crotyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate and isobornyl methacrylate. Preferably, it is at least one of methyl acrylate, butyl acrylate, methyl methacrylate and butyl methacrylate.

3. The chain extender according to claim 1, wherein The (alkyl) acrylate polymer monomer containing an epoxy group includes at least one of glycidyl acrylate and glycidyl methacrylate; The (alkyl) acrylate polymer monomer containing a tertiary amine group includes at least one of dimethylaminoethyl acrylate, diethylaminoethyl acrylate, diisopropylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and diisopropylaminoethyl methacrylate. Preferably, it is at least one of dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate. And / or, the styrene-based polymerizable monomer includes at least one of styrene, methyl styrene, tert-butyl styrene and o-chlorostyrene, preferably styrene.

4. The chain extender according to claim 2, wherein The mass of the (alkyl) acrylate polymer monomer containing an epoxy group accounts for 20wt%-45wt% of the total mass of all polymer monomers; the mass of the (alkyl) acrylate polymer monomer containing a tertiary amine group accounts for 5wt%-20wt% of the total mass of all polymer monomers; the mass of the styrene polymer monomer accounts for 50wt%-75wt% of the total mass of all polymer monomers; and the (alkyl) acrylate polymer monomer accounts for 0wt%-30wt% of the total mass of all polymer monomers. Preferably, the chain extender has a weight average molecular weight Mw of 5,000-100,000 g / mol, preferably 5,000-50,000 g / mol. Preferably, the molecular weight distribution PDI of the chain extender is 1.5-5, preferably 2-3.

5. Preferably, the epoxy equivalent weight of the chain extender is 2000-100 g / mol, preferably 1400-150 g / mol.

5. A chain extender comprising at least one copolymer; the copolymer comprising a repeating unit represented by Formula 1, a repeating unit represented by Formula 2, and a repeating unit represented by Formula 3: In formula 1, R1 is selected from C 1-6 Alkyl or H; * is the connection end; In formula 2, R2 is selected from C 1-6 Alkyl or H; R3 is selected from C 1-12 Alkylene; R4 and R5 are the same or different and are independently selected from substituted or unsubstituted C 1-12 Alkyl; if substituted, the substituent is halogen or C 1-12 Alkyl; * is the connecting end; In formula 3, R6 is selected from C 1-6 Alkyl or H; R7, R8, R9, R 10 and R 11 the same or different, independently selected from halogen, substituted or unsubstituted C 1-12 Alkyl; if substituted, the substituent is halogen or C 1-12 Alkyl; * is the connecting end.

6. The chain extender according to claim 5, wherein The copolymer further comprises a repeating unit shown in Formula 4: In formula 4, R 12 Selected from C 1-6 Alkyl or H; R 13 Selected from C 1-40 Aliphatic group or C 3-40 Alicyclic group; * is the connecting end.

7. The chain extender according to claim 5, wherein The mass of the repeating unit represented by formula 1 accounts for 20wt%-45wt% of the total mass of the copolymer; the mass of the repeating unit represented by formula 2 accounts for 5wt%-20wt% of the total mass of the copolymer; the mass of the repeating unit represented by formula 3 accounts for 50wt%-75wt% of the total mass of the copolymer; the mass of the repeating unit represented by formula 4 accounts for 0wt%-30wt% of the total mass of the copolymer.

8. A method for preparing the chain extender according to any one of claims 1 to 7, comprising the steps of: An epoxy group-containing (alkyl) acrylate polymerization monomer, a tertiary amine group-containing (alkyl) acrylate polymerization monomer, a styrene polymerization monomer, an optionally added (alkyl) acrylate polymerization monomer, a solvent, and a free radical initiator are added to a reaction kettle. The reaction kettle is vacuum deoxygenated, then filled with an inert gas, and heated to initiate a polymerization reaction. After the polymerization reaction is completed, the solvent and unreacted polymerization monomers in the reaction system are removed to prepare the chain extender. Preferably, the polymerization reaction temperature is 60-180° C., preferably 80-150° C.; and the polymerization reaction time is 1-15 h.

9. Use of the chain extender according to any one of claims 1 to 7, wherein the chain extender is used for chain extension of a polymer having active hydrogen at its terminal group. Preferably, the chain extender is used for the recovery, branching modification and blending modification of high molecular polymers containing active hydrogen at the end groups. Preferably, the polymer containing active hydrogen at the end group includes at least one of polyester (including polylactic acid (PLA)), polyamide (PA), polycarbonate (PC), polyurethane (PU), polyacetal, polysulfone, polyphenylene ether (PPE), polyethersulfone, polyimide, polyetherimide, polyetherketone, polyetheretherketone, polyaryletherketone or polyphenylene sulfide.

10. A composition comprising the chain extender according to any one of claims 1 to 7 and a high molecular polymer having active hydrogen at its terminal group. Preferably, the mass of the chain extender accounts for 0.5-5 wt% of the total mass of the composition.

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