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Ethylene-vinyl alcohol copolymer resin and particle producing method thereof, the resin particle

A copolymer and vinyl alcohol technology, applied to the preparation of ethylene-vinyl alcohol copolymer resin and its pellets, can solve the problems of thermal stability decline, easy adhesion, poor quality, etc.

Inactive Publication Date: 2004-04-21
KURARAY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As a specific problem, the bridge phenomenon occurs in the feeding hopper, which makes it difficult to supply the raw material resin to the extruder.
Or water is supplied to the extruder on the separated surface of the feeder, and water vapor is generated in the lower part of the hopper, causing the raw material pellets to stick, so the supply of raw materials to the extruder becomes poor.
In particular, when EVOH contains water, the lowering of the melting point is easily affected, and the pellets tend to stick to each other at the lower part of the hopper, and as the influence of poor supply on quality, the supply amount to the extruder fluctuates, so The amount of acid and metal salt added is unstable, which causes problems such as a decrease in thermal stability

Method used

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  • Ethylene-vinyl alcohol copolymer resin and particle producing method thereof, the resin particle
  • Ethylene-vinyl alcohol copolymer resin and particle producing method thereof, the resin particle
  • Ethylene-vinyl alcohol copolymer resin and particle producing method thereof, the resin particle

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0221] The EVOH with ethylene content 32 mol%, saponification degree 99.5 mol%, water content 35% by weight is dropped into such as figure 1 In the recorded twin-screw extruder, set the resin temperature at the outlet to 100°C, from figure 1 In the trace component addition portion at the front end portion on the discharge port side shown, a treatment liquid composed of acetic acid / boric acid / sodium acetate / magnesium acetate / potassium dihydrogen phosphate aqueous solution is added. The input amount of EVOH per unit time is 10kg / hr (including the weight of water contained therein), the input amount of treatment liquid per unit time is 0.65L / hr, and the composition of the treatment liquid is 4.3g / L acetic acid, 15g / L Aqueous solution of boric acid, 4.6g / L sodium acetate, 3.0g / L magnesium acetate, 1.4g / L potassium dihydrogen phosphate. The specifications of the twin-screw extruder are as follows (details are described in figure 1 middle).

[0222] Form Twin-screw extruder

[0...

Embodiment 2-4

[0252] In addition to changes in the ethylene content in EVOH, degree of saponification, resin temperature in the extruder, moisture content before feeding into the extruder, and moisture content immediately after discharge from the extruder as summarized in Table 1, Except that the addition amount of EVOH per unit time and the addition amount per unit time of at least one solution selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt and its composition are changed as shown in Table 2, EVOH pellets were produced in the same manner as in Example 1. The extrusion conditions are shown in Table 1, the composition of the treatment liquid is shown in Table 2, the composition of the obtained EVOH pellets is shown in Table 3, and the evaluation results are shown in Table 4.

Embodiment 5

[0294] EVOH having an ethylene content of 32 mol%, a degree of saponification of 99.5 mol%, a water content of 40% by weight, and a sodium ion content of 1.5% by weight in terms of metals is supplied to such as image 3 Inside the twin-screw extruder shown. The twin-screw extruder consists of a raw material supply part, a cleaning liquid addition part, and a dehydration part, and a wedge-shaped wire-shaped dehydration slit is arranged at the dehydration part. Add 0.5g / L acetic acid aqueous solution from the cleaning solution addition site. The unit time input amount of EVOH is 50kg / hr (including the weight of contained water), the unit time input amount of acetic acid aqueous solution is 600L / hr, and the EVOH residence time is 5 minutes. The EVOH discharged from the wire die installed at the front end of the extruder was cut into pellets with a pelletizer. The specifications of the twin-screw extruder are shown below.

[0295] Form Twin-screw extruder

[0296] L / D 42

[0...

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Abstract

A process for producing an ethylene-vinyl alcohol copolymer resin, including feeding EVOH into an extruder, keeping the temperature of the melting resin in the extruder at 70 to 170 DEG C, adjusting the amount of water in the extruder so that the water content right after being discharged from the extruder is 5 to 40 weight %, and extruding out the EVOH resin. The extruded EVOH resin is cut into EVOH pellets. Thereby, it is possible to obtain resin pellets in which no spherocrystals are observed in the center of the cross section of the resin when the cross section is observed by the use of a polarization microscope, or no lubricant is contained in the resin pellets, and the angle of repose is 23 DEG or less when the resin pellets are laminated. Thus, it is possible to provide an ethylene-vinyl alcohol copolymer (EVOH) resin pellet having a reduced discharging load to the environment and capable of being fed into an extruder smoothly without being blocked, extruding stability, and thermal stability (long-run property).

Description

[0001] This application is a divisional application of the Chinese patent application No. 00128695.1 filed on July 23, 2000 entitled "Method for preparing ethylene-vinyl alcohol copolymer resin and its pellets, and the resin pellets" . technical field [0002] The present invention relates to a method for preparing ethylene-vinyl alcohol copolymer (hereinafter also referred to as EVOH) with good thermal stability and low production cost, a method for preparing pellets thereof, and resin pellets obtained by the method. Background technique [0003] EVOH has high gas barrier properties, excellent oil resistance, organic solvent resistance, fragrance retention, and transparency, so it can be widely used as food packaging. As food packaging materials, various forming processing methods can be used: for example, extrusion forming into films, blow molding into bottles, vacuum forming into various bags, etc. [0004] With these various molding processing methods, the molding proce...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F6/28B29B9/06B29C48/05B29C48/08B29C48/09B29C48/12B29C48/76C08F6/00C08F6/02C08F210/02C08J3/12C08J3/22C08L25/06
CPCC08F6/28B29C47/761B29C47/0004C08K3/38B29C47/003C08J2329/04C08J3/12B29C2793/009C08K3/0083C08F210/02B29K2029/04C08L25/06B29C47/0021B29C47/0014C08F6/02C08K3/32B29B9/06C08K5/09B29C47/762B29C47/0023C08F6/005C08K3/105B29C48/05B29C48/022B29C48/08B29C48/09B29C48/12B29C48/761B29C48/762B29B9/065B29B7/007B29B7/46B29B7/726B29B7/845B29B7/90B29B9/12B29B9/14C08L29/04C08L2666/04C08F216/06C08J3/22
Inventor 川原孝春河合宏坪井俊雄大原行博日笠正雄
Owner KURARAY CO LTD
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