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Priority claimed from US07/031,317external-prioritypatent/US4900633A/en
Priority claimed from US07/031,315external-prioritypatent/US4920006A/en
Priority claimed from US07/031,319external-prioritypatent/US4861669A/en
Application filed by Ppg Industries IncfiledCriticalPpg Industries Inc
Priority claimed from EP88104212Aexternal-prioritypatent/EP0283923B1/de
Application grantedgrantedCritical
Publication of ATE54953T1publicationCriticalpatent/ATE54953T1/de