1
                                                                    Exhibit 3.5
                                          to Registration Statement on Form S-4

                         CERTIFICATION OF INCORPORATION
                                       OF
                                RBX-GROENDYK INC.

       The undersigned incorporator, for the purpose of incorporating or
organizing a corporation under the General Corporation Law of the State of
Delaware, certifies:

       FIRST:    The name of the Corporation is

                   RBX-Groendyk Inc.

       SECOND:   The address of the Corporation's registered office in the State
of Delaware is Corporation Trust Center, 1209 Orange Street, in the City of
Wilmington, County of New Castle. The name of its registered agent at such
address is The Corporation Trust Company.

       THIRD:    The purpose of the Corporation is to engage in any lawful act 
or activity for which corporations may be organized under the General 
Corporation Law of Delaware.

       FOURTH:   The total number of shares of stock which the Corporation shall
have authority to issue is One Thousand (1,000) shares of Common Stock, and the
par value of each such share is One Dollar ($1.00)

       FIFTH:    The name and mailing address of the incorporator is Rory A.
Babich, Paul, Weiss, Rifkind, Wharton & Garrison, 1285 Avenue of the Americas,
New York, New York 10019-6064.

       SIXTH:    Elections of directors need not be by ballot unless the 
By-Laws of the Corporation shall so provide.

       SEVENTH:  The Board of Directors of the Corporation may make By-Laws and
from time to time may alter, amend or repeal By-Laws.

       EIGHTH:    To the fullest extent permitted by the Delaware General
Corporation Law as the same exists or may hereafter be amended, a Director of
the Corporation shall not be liable to the Corporation or its stockholders for
monetary damages for breach of fiduciary duty as a Director.

       IN WITNESS WHEREOF, I have signed this Certificate this 24th day of
September, 1990.

                                  /s/   Rory A. Babich
                              ---------------------------------
                                   Rory A. Babich



   2



                           AMENDMENT OF CERTIFICATE OF
                         INCORPORATION AFTER RECEIPT OF
                                PAYMENT FOR STOCK

                                       OF

                                RBX-GROENDYK INC.



       It is hereby certified that:

       1.    The name of the corporation (the "Corporation") is RBX-Groendyk 
Inc.

       2.    The certificate of incorporation of the Corporation is hereby 
amended by striking out Article 1 thereof and by substituting in lieu of said 
Article the following new Article:

       FIRST:     The name of the Corporation is

                  Groendyk Manufacturing Company, Inc..

       3.    The amendment of the certificate of incorporation of the 
Corporation herein certified was duly adopted, in accordance with the 
provisions of Section 242 of the General Corporation Law of the State of 
Delaware.

Attest:

                                      /s/   Alan W. Wilkinson
                                  -----------------------------------
                                  Name:  Alan W. Wilkinson
                                  Title: Vice President

  /s/  Christine J. Smith
- -----------------------------
Name:  Christine J. Smith
Title:   Secretary



Dated:  December 14, 1990



   3


                       CERTIFICATE OF CHANGE OF REGISTERED

                           OFFICE AND REGISTERED AGENT

                                       OF

                      GROENDYK MANUFACTURING COMPANY, INC.


              -------------------------------------------------

           The Board of Directors of:

                      GROENDYK MANUFACTURING COMPANY, INC.

a Corporation of the State of Delaware, on this 1st day of October, A.D. 1997,
do hereby resolve and order that the location of the Registered Office of this
Corporation within this State be, and the same hereby is:

1013 Centre Road, in the City of Wilmington, in the County of New Castle,
Delaware, 19805. 

           The name of the Registered Agent therein and in charge thereof upon
whom process against the Corporation may be served, is:

CORPORATION SERVICE COMPANY.

                      GROENDYK MANUFACTURING COMPANY, INC.

a Corporation of the State of Delaware, does hereby certify that the foregoing
is a true copy of a resolution adopted by the Board of Directors at a meeting
held as herein stated.

       IN WITNESS WHEREOF, said corporation has caused this Certificate to be
signed by Harry L. Schickling, this 1st day of October A.D. 1997.



                                  /s/ Harry L. Schickling            
                             -------------------------------
                               VP & Secretary
                               Authorized Officer