Preparation of PU binder resin for synthetic leather

Abstract

The invention relates to a method for manufacturing PU adhesive resin for synthetic leather. The method comprises the following steps that: (i) AA and MPD are heated to undergo esterification and polycondensation reaction, when reaction is carried out till acid value is less than or equal to 25 mgKOH / g, reactant is vacuumized, residual water is removed, the acid value is reduced, when the reaction is carried out till the acid value is less than or equal to 2.5mgKOH / g, the vacuum degree is enlarged, and the reaction is continuously carried out to prepare hydroxyl-end capped MPD type polylol; and (ii) the MPD type polylol prepared in step (i) and a chain extender MPD are mixed, added with DMF, evenly stirred, added with MDI, heated and reacted, and polymerized to generate polyurethane; the polyurethane is added with the DMF and MEK; and the viscosity is adjusted between 12*10 MPa.s / 25 DEG C. The adhesive resin prepared by the method is a semiliquid type PU adhesive, has the advantages of high connecting strength, peeling performance, hot dry pasting, good resin permeability, and the like, can be used for common synthetic leather, and is in particular suitable for ultrafine fiber leather and mirror face rear pasting leather.

Description

technical field [0001] The present invention relates to a kind of manufacture method of PU binder resin for synthetic leather, Background technique [0002] Polyols used in PU binder resins are usually polyester polyols such as ethylene glycol, 1,4-butanediol, diethylene glycol, octapentyl glycol, and 1,6-hexanediol. , Only ethylene glycol and 1,4-butanediol are used as chain extenders. The bonding strength of general PU leather can be produced by using PU binder resin of linear polyols, but there are always various kinds of binders for high-grade synthetic leather such as special microfiber leather and mirror-coated leather. Such limitations. [0003] In the production of synthetic leather, a layer of solvent-diluted PU resin is usually applied on the release paper to a viscosity of 3000-6000cps / 25°C, and the dry-process surface layer PU resin is added with coloring material, and dried; and then coated with a layer Solvent dilutes the viscosity to 6000-20000cps / 25℃, and ...

AI Technical Summary

Problems solved by technology

However, the solid content of this type of adhesive is generally only up to 50%. In the winter environment, the resin tends to become turbid or agglomerated, and the produced synthetic leather has low bonding strength and poor elasticity, so it is not suitable for superfiber synthesis. Lamination of leather; and because of its high softening point, usually above 160°C, it is not suitable for the dry lamination process of mirror-like synthetic leather

Japan, South Korea and a small number of domestic large-scale synthetic leather companies usually use two-component PU adhesives. This type of adhesive overcomes the shortcomings of one-component adhesives, and has excellent performance in bonding strength, elasticity, etc., and the resin is transparent. Good performance, can achieve a high solid content of more than 50%, but the two-component PU binder resin has more soft segments, the viscosity stability is poor at the end of the reaction, and the viscosity is easy to drop during storage; use two-component PU for bonding Synthetic leather produced by synthetic resin needs to be placed in a warm room at 60°C to 80°C for 24 to 48 hours before the release paper and synthetic leather can be separated. This usually brings about several problems, one of which is high energy consumption. , it is necessary to build a constant temperature greenhouse, and the larger the output per unit time, the larger the greenhouse area requirement; the second problem is that the turnover of release paper is slow, and more release paper needs to be reserved; the third problem is release paper The use of paper is limited, some release papers that are not resistant to high temperature cannot be used, it is difficult to peel off the release paper and synthetic leather, and the number of times the release paper is used is significantly reduced; the fourth problem is that the product has poor embossing effect