低熔点聚酯生产工艺探讨

Discussion of production process of low-melting point polyester

利用现有装置设施,采用共聚法,将第三单体、乙二醇、钛系催化剂加入浆料罐,与精对苯二甲酸经酯化、缩聚生产熔点为250℃的低熔点聚对苯二甲酸乙二醇酯(PET)切片,探讨了其生产工艺。结果表明:第三单体的加入对酯化、缩聚反应有较大的抑制作用;与常规PET切片相比,低熔点PET切片的色度b值升高0.5～1.0,但均控制在指标值(4.6)以下,端羧基含量降低2～3 mol/t,二甘醇质量分数升高0.40%～0.60%;低熔点PET切片用于纺粘针刺无纺布生产时,热轧温度降低4℃,得到的无纺布纵向和横向强力分别由410,395 N提高至500,475 N。

Low-melting point polyethylene terephthalate(PET)chips with the melting point of 250℃were prepared by polymerization process comprising esterification and condensation of purified terephthalic acid with the third monomers,ethylene glycol and titanium catalysts in slurry tanks on existing facilities.The production process was discussed.The results showed that the addition of the third monomer had a great inhibition on the esterification and condensation reactions;compared with conventional PET chips,the chroma b value of low-melting point PET chips had a growth of 0.5-1.0 but should be controlled below 4.6,the carboxyl end group content decreased by 2-3 mol/t,and the mass fraction of diethylene glycol increased by 0.40%-0.60%;and the longitudinal and transverse strength of the obtained nonwoven fabric increased from 410 and 395 N to 500 and 475 N,respectively,when low-melting point PET chips were used for preparing nonwoven fabric by spun-bonding needle-punching process and the hot-rolling temperature was decreased by 4℃.