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Polymers Division

A processing guide for

INJECTION MOLDING

T E X I N AND D E S M O P A N
T H E R M O P L A S T I C P O LY U R E T H A N E S

TABLE OF CONTENTS

INTRODUCTION 5 5 6 6 6 7 7 8 8 Product Description Product by Grade Type Product by Market Nomenclature Grade Designation Color Designation Coloring the Resin Coloring Molded Parts Packaging and Labeling

INJECTION MOLDINGPROCESS 20 20 20 21 22 22 22 22 23 23 23 Typical Processing Temperatures Barrel Heating Zones Nozzle Melt Temperature Machine Conditions Injection Pressures Hold Pressure Injection Speed Injection Cushion Back Pressure Screw Speed Clamp Tonnage Mold Temperature Shot Weight Cycle Time Mold Release Agents Part Ejection Using Regrind Machine Preparation Purging and Cleaning Starup Procedure ShutdownProcedure Temporary Shutdown Short-Term Shutdown Long-Term Shutdown Changing from Texin or Desmopan Resins to Another Material 27 Post-Mold Conditioning

MACHINE SELECTION 9 9 Machine Type and Design Screws: Material, Configuration, and Wear 10 10 11 11 12 13 13 13 Non-Return Valves Nozzle Types and Tips Nozzle Temperature Control Process Controls Temperature Time and Pressure Shot Size andMachine Capacity Machine Ventilation

24 24 25 25 25 25 25 26 26 27 27 27 27 27

DRYING 14 14 14 16 Material Handling Drying Equipment Desiccant Hopper Drying Hot Air Oven Drying

27

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TABLE OF CONTENTS, continued

TOOLING 29 29 29 29 29 30 30 30 30 30 32 32 32 32 32 33 33 33 34 34 35 35 35 35 35 36 Mold Shrinkage Mold Design Material Selection Surface Finish Venting Part DraftTexturing Weld Lines Undercuts Tolerances Mold Cooling Mold Types 2- or 3-Plate Molds Single- and Multiple Cavity Molds Sprue Bushings Sprue Pullers Runners and Runner Systems Hot Runner Molds Gating Sprue Gate Edge Gates Disc and Ring Gates Pinpoint Gates Insert Molding Metal Inserts Nonmetal Inserts /Over-Molding

SAFETY CONSIDERATIONS 46 46 General Health and Safety Precautions

GENERALINFORMATION 47 47 47 47 48 48 Developmental Product Information Regulatory Compliance Medical Grade Information Sterilization Information Biocompatibility Information Technical Support

APPENDIX A 49 List of Tables

APPENDIX B 50 List of Figures

INDEX 51 Index

TROUBLESHOOTING GUIDE 38 39 40 41 42 43 44 45 Blisters and Splay Marks Burn Marks Flash Short Shots Sinks Sticking Parts Voids Warpage

3INTRODUCTION

PRODUCT DESCRIPTION Texin and Desmopan resins are thermoplastic polyurethane elastomers (TPUs) based on polyesters, polyethers, special copolymers, and blends of polyurethane and polycarbonate, which exhibit a wide range of properties suitable for many different applications. Finished parts made from Texin and Desmopan resins possess all the excellent properties which arenormally associated with polyurethane elastomers. These properties include:

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High tensile and tear strength. Excellent abrasion resistance. Excellent resistance to fuels, oils, ozone, and oxygen. High elasticity and resilience combined with high load-bearing capacity and hardness. Hydrolysis and microbe resistance.

Product by Grade Type

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Texin and Desmopan resins areavailable in unreinforced general-purpose grades of various hardness. Desmopan KU2-8651 resin, the softest grade available, is used in applications where high flexibility is required. Desmopan 453 resin, a harder and more rigid grade, is used for low-deflection, loadbearing applications. Texin 390 resin has intermediate hardness and modulus. Several modifications of the general Texin and Desmopanresin grades which have been designed to meet

Table 1

Texin and Desmopan TPU Injection Molding Resins

Resin Type Old Name New Name
Polyesters – Specialty Texin 345D Texin 355D Texin 360D Desmopan 445 Desmopan 453 Desmopan 459

Shore Hardness

Resin Type Old Name
Polyethers, continued

New Name

Shore Hardness

45D 53D 60D

Texin DP7-1047 Texin DP7-1051 Texin DP7-1052 Texin...