Method for preparing polyester-polyester blocked copolyester

Abstract

The invention discloses a method for preparing polyester-polyester blocked copolyester, which comprises the following steps: (1) synthesizing an aromatic polyester hard segment to obtain a prepolymer P1 with a number-average molecular weight in the range of 500-10,000g / mol; (2) synthesizing an aliphatic polyester soft segment to obtain a prepolymer P2, wherein the prepolymer P2 can also be obtained by ring-opening polymerization of caprolactone monomer, and the number-average molecular weight of the prepolymer P2 is in the range of 500-10,000g / mol; (3) carrying out polycondensation reaction of the aromatic polyester oligomer and the aliphatic polyester oligomer: mixing the esterified product P1 and the esterified product P2, adding antioxidant, catalyst, passsivator and chain expander, allowing reaction at 220-260 DEG C to obtain a polyester-polyester block polyester elastomer. The catalysts used in the steps (1) and (2) are selected from titanium-containing organic substances. The method disclosed by the invention has the following advantages: (1) because the aliphatic polyester soft segment is introduced, the product has both the mechanical properties of the rigid aromatic polyester hard segment and the flexibility of the soft segment; and (2) because a number of assistants are added, the good chain expansion effect is achieved, and the reaction conditions are controlled.

Description

technical field [0001] The invention relates to a method for preparing copolyester, in particular to a method for preparing polyester-polyester block copolyester. Background technique [0002] Polyester thermoplastic elastomer has the characteristics of both rubber and thermoplastic engineering plastics. It exhibits the characteristics of rubber at room temperature and the characteristics of thermoplastics at high temperature. It can be plasticized and molded, and it is easy to process. Its molecular structure consists of hard segment and soft segment. The hard segment is aromatic polyester (PET or PBT), and the polyether or polyester block with a lower glass transition temperature is used as the soft segment. It is elastic at the use temperature. Partial crystallization of the polyester hard segment of the polyether / polyester forms a crystalline microdomain, and the polyether / polyester soft segment and uncrystallized hard segment form an amorphous phase, and the crystallin...

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Problems solved by technology

[0005] U.S. Patent US 2006 / 0252864A1 uses commercially available polybutylene terephthalate, caprolactone monomer, butanediol and other monomers to pass through and exchange reactions, and then carry out polycondensation to obtain a PBT-PCL Copolymer, but since the caprolactone used is a monomer structure, polybutylene terephthalate will inevitably participate in the transesterification reaction during the reaction, resulting in the soft segment and the hard segment being a randomly distributed structure

[0006] Chinese patent 200910092100.0 discloses a biodegradable aliphatic polyester / aromatic polyester multi-block copolymer and its preparation method and application. The preparation method is to first synthesize aliphatic polyester prepolymer A, and then synthesize aromatic family or alicyclic prepolymer B, and then synthesize the corresponding multi-block copolymer under the effect of chain extender, its advantage is that in crystalline aliphatic polyester, introduce rigid non-crystalline polyester segment, Biodegradable aliphatic polyester / aromatic polyester multi-block copolymers are obtained, which give good mechanical properties, but have the disadvantages of poor processability and poor stability

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