<PAGE>

                                                           EXHIBIT 4.20

                   SUBSIDIARIES' PATENT SECURITY AGREEMENT

          SUBSIDIARIES' PATENT SECURITY AGREEMENT, dated as of December 11,
1997, made by each corporation identified on Schedule A hereto (each such
entity, a "Grantor"), in favor of STATE STREET BANK AND TRUST COMPANY, a
Massachusetts trust company, as trustee (in such capacity, the "Trustee") for
holders of the Notes (as hereinafter defined) (the "Noteholders"), pursuant to
the Indenture, dated as of December 11, 1997 (as amended, supplemented or
otherwise modified from time to time, the "Indenture"), among RBX Corporation,
a Delaware corporation, as issuer (the "Company"), Groendyk Manufacturing
Company, Inc., Hoover-Hanes Rubber Custom Mixing Corp., Midwest Rubber Custom
Mixing Corp., OleTex Inc., Rubatex Corporation, Universal Polymer & Rubber
Inc., Universal Rubber Company and Waltex Corporation, as guarantors (the
"Subsidiary Guarantors"), and the Trustee.

                                  WITNESSETH
                                  ----------
          WHEREAS, the Company will issue 12% Senior Secured Notes due 2003 in
the aggregate principal amount of $100,000,000 (the "Notes") pursuant to the
Indenture;

          WHEREAS, it is a requirement of the Indenture that each Grantor
guarantees payment and performance of the Company's obligations under the
Indenture, the Notes and the other Collateral Documents (as defined);

          WHEREAS, in satisfaction of such condition, each Grantor has entered
into a Subsidiary Guarantee of even date herewith (as amended, supplemented or
otherwise modified from time to time, the "Subsidiary Guarantees") for the
benefit of the Trustee and the Noteholders;

          WHEREAS, each Grantor has executed and delivered the Subsidiaries'
Security Agreement, of even date herewith (as amended, supplemented or
otherwise modified from time to time, the "Subsidiaries' Security Agreement"),
in favor of the Trustee for the benefit of the Noteholders;

          WHEREAS, each Grantor owns, or is licensed to use, the Patents and
Patent Licenses (each as hereinafter defined) described on Schedule 1 hereto;

          WHEREAS, pursuant to the terms of the Subsidiaries' Security
Agreement, each Grantor has mortgaged, pledged and granted to the Trustee, for
the benefit of the Trustee and the Noteholders, a security interest in all
right, title and interest of each Grantor in, to and under the Collateral (as
hereinafter defined), including the property described on Schedule 1 hereto,
whether presently existing or hereafter arising or acquired, and all Proceeds
thereof, including, without limitation, any and all causes of action which may
exist by reason of infringement thereof for the full term of the Patents, to
secure the payment of the Obligations (as hereinafter defined);

          WHEREAS, for convenience of reference and recordation, but with no
intention to supersede the terms of the Subsidiaries' Security Agreement, the
parties hereto have entered into this Patent Security Agreement; and

          WHEREAS, it is a further requirement of the Indenture that each
Grantor shall have executed and delivered this Patent Security Agreement to
the Trustee for the benefit of the Trustee and the Noteholders.

          NOW, THEREFORE, in consideration of the premises, each Grantor
hereby agrees with the Trustee, for the benefit of the Trustee and the
Noteholders, as follows:
<PAGE>

          1.     Defined Terms.  (a)  Unless otherwise defined herein, terms
defined in the Indenture and used herein shall have the meanings given to them
in the Indenture.  The following terms which are defined in the Uniform
Commercial Code in effect in the State of New York on the date hereof are used
herein as so defined:  Accounts, Chattel Paper, Documents, Equipment, General
Intangibles, Instruments, Inventory and Proceeds.

               (b)     The following terms shall have the following
        meanings:

               "Closing Date":  the date of the Indenture.

               "Code":  the Uniform Commercial Code as from time to time in
effect in the State of New York.

               "Collateral":  as defined in Section 2 of this Patent Security
Agreement.

          "Governmental Authority":  any nation or government, any state or
other political subdivision thereof and any entity exercising executive,
legislative, judicial, regulatory or administrative functions of or pertaining
to government.

          "Material Adverse Effect":  a material adverse effect on (a) the
business, assets, operations, property or condition (financial or otherwise)
of the Company and the Subsidiary Guarantors, taken as a whole, (b) the
ability of the Company or any of the Subsidiary Guarantors to perform their
respective obligations under the Indenture, the Notes, the Subsidiary
Guarantees, the Registration Rights Agreement and the Collateral Documents,
(c) the validity or the enforceability of the Indenture, the Notes, the
Subsidiary Guarantees, the Registration Rights Agreement and the Collateral
Documents or (d) the rights or remedies of the Trustee, for the benefit of the
Trustee and the Noteholders, hereunder or thereunder.

               "Obligations": as defined as "Guarantee Obligations" in the
Indenture.

          "Patents":  (i) all letters patent of the United States and all
reissues and extensions thereof, including, without limitation, those listed
in Schedule 1 hereto, and (ii) all applications for letters patent of the
United States or of any other country and all divisions, continuations and
continuations-in-part thereof, including, without limitation, those listed in
Schedule 1 hereto.

          "Patent Security Agreement":  this Patent Security Agreement, as the
same may be amended, supplemented or otherwise modified from time to time.

          "Patent Licenses":  all agreements, whether written or oral,
providing for the grant by each Grantor of any right to manufacture, use or
sell any invention covered by a Patent, including, without limitation, those
listed in Schedule 1 hereto.

          "RBX Parties":  the Company, the Subsidiary Guarantors and any new
Subsidiary complying with Section 4.14 of the Indenture; individually, a "RBX
Party."

                                       2
<PAGE>

          "Requirement of Law":  as to any Person, the certificate of
incorporation and by-laws or other organizational or governing documents of
such Person, and any law, treaty, rule or regulation or determination or an
arbitrator or a court of other Governmental Authority, in each case applicable
to or binding upon such Person or any of its material property (including the
properties subject to the Mortgages and Deeds of Trust) or to which such
Person or any of its material property is subject.

          2.     Security Interest.

          (1)     Grant of Security Interest.  As collateral security for the
prompt and complete payment and performance when due (whether at the stated
maturity, by acceleration or otherwise) of the Obligations, each Grantor
hereby grants to the Trustee for the benefit of the Trustee and the
Noteholders, and their successors and assigns, a security interest in all of
the following property now owned or at any time hereafter acquired by each
Grantor or in which each Grantor now has or at any time in the future may
acquire any right, title or interest (collectively, the "Collateral"):

               (1)     all Patents;

               (2)     all Patent Licenses;

               (3)     all General Intangibles relating to Patents and Patent
Licenses; and

               (4)     to the extent not otherwise included, all Proceeds and
products of any and all of the foregoing,

to have and to hold, together with all rights, titles, interests, powers,
privileges and preferences pertaining or incidental thereto for the benefit of
the Noteholders.

          (2)     No Assumption of Liability.  The security interest in the
Collateral is granted as security only and shall not subject the Trustee to,
or in any way alter or modify, any obligation or liability of any Grantor with
respect to or arising out of the Collateral.

          3.     Representations and Warranties.  Each Grantor hereby
represents and warrants that:

          (1)     Patents.  Schedule 1 hereto includes all registered U.S.
Patents owned by each Grantor on the date hereof and all other Patents and
Patent Licenses owned by each Grantor in its own name as of the date hereof
which are material to the business of the Company and its Subsidiaries, taken
as a whole.  To the best of each Grantor's knowledge, each Patent is valid,
subsisting, unexpired, enforceable and has not been abandoned, except to the
extent that the failure to be valid, subsisting, unexpired or enforceable or
the abandonment thereof would not be reasonably likely to have a Material
Adverse Effect.  Except as set forth in such Schedule, none of such Patents is
the subject of any licensing or franchise agreement.  No holding, decision or
judgment has been rendered by any Governmental Authority which would limit,
cancel or question the validity of any Patent except for such holdings,
decisions or judgments that would not be reasonably likely to have

                                       3
<PAGE>

a Material Adverse Effect.  No action or proceeding is pending seeking to
limit, cancel or question the validity of any Patent, which, if adversely
determined, would be reasonably likely to have a Material Adverse Effect.

          (2)     Chief Executive Office.  As of the Closing Date, each
Grantor's chief executive office and chief place of business is located at
5221 ValleyPark Drive, Roanoke, VA 24019.

          4.     Covenants. Each Grantor covenants and agrees with the Trustee
and the Noteholders that, from and after the date of this Agreement until the
payment in full or Legal Defeasance of all principal of, interest on, premium,
if any, and Liquidated Damages, if any, with respect to the Notes and any
other Obligations for the payment of money then due and owing to any
Noteholder or the Trustee under the Indenture or any Collateral Document:

                  (1)     Further Documentation.  At any time and from time to
        time, upon the written request of the Trustee, and at the sole expense
        of each Grantor, each Grantor will promptly and duly execute and
        deliver such further instruments and documents and take such further
        action as the Trustee may reasonably request for the purpose of
        obtaining or preserving the full benefits of this Patent Security
        Agreement and the rights and powers herein granted.

                  (2)     Indemnification.

                          (1)     Each Grantor agrees to pay, and to save the
                Trustee and the Noteholders harmless from, any and all
                liabilities, costs and expenses (including, without
                limitation, legal fees and expenses) (1) with respect to, or
                resulting from any delay in paying, any and all excise, sales
                or other taxes that may be payable or determined to be payable
                with respect to any of the Collateral, (2) with respect to, or
                resulting from, any delay in complying with any Requirement of
                Law applicable to any of the Collateral and (3) in connection
                with any of the transactions contemplated by this Patent
                Security Agreement.  In any suit, proceeding or action brought
                by the Trustee or any Noteholder for any amounts owed, each
                Grantor will save, indemnify and keep the Trustee and such
                Noteholder harmless from and against all expense, loss or
                damage suffered by reason of any defense, setoff,
                counterclaim, recoupment or reduction or liability whatsoever
                of the account debtor or obligor thereunder, arising out of a
                material breach by such Grantor of any obligation thereunder
                or arising under any other agreement, indebtedness or
                liability at any time owing to or in favor of such account
                debtor or its successors from such Grantor.  The Trustee may
                have separate counsel and the Grantors shall pay the
                reasonable fees and expenses of such counsel.  The Grantors
                need not pay for any settlement made without its consent,
                which consent shall not be unreasonably withheld.

                          (2)     Before the Trustee acts or refrains from
                acting, it may require an Officers' Certificate or an Opinion
                of Counsel or both.  The Trustee shall not be liable for any
                action it takes or omits to take in good faith in reliance on
                such Officers' Certificate or Opinion of Counsel.  The Trustee
                may consult with counsel

                                       4
<PAGE>

                and the written advice of such counsel or any Opinion of
                Counsel shall be full and complete authorization and
                protection from liability in respect of any action taken,
                suffered or omitted by it hereunder in good faith and in
                reliance thereon.

          (3)     Patents.

                  (1)     Each Grantor will not (either itself or through
        licensees), except with respect to any Patent that each Grantor shall
        reasonably determine is not material to the business of the Company
        and its Subsidiaries taken as a whole, do any act or omit to do any
        act, whereby the registration of any such Patent may become abandoned
        or dedicated.

                  (2)     Each Grantor will notify the Trustee of any (A)
        abandonment or dedication of a Patent (other than foreign patents and
        applications with respect thereto) ("U.S. Patent"); or (B)
        determination by a court or tribunal in the country where (1) the
        Patent is registered, or (2) the Patent application is pending, that
        such Grantor does not own all rights, title and interest to the U.S.
        Patent, or of any other adverse determination of such court or
        tribunal relating to any Patent; provided that (x) such Grantor has
        actual notice of such event and (y) such Patent or Patent application
        is material to the business of the Company and its Subsidiaries, taken
        as a whole.

                  (3)     Whenever each Grantor, either by itself or through
        any agent, employee, licensee or designee, shall file an application
        for the registration of a Patent with the United States Patent and
        Trademark Office (the "PTO") or any, similar office or agency in any
        other country or any political subdivision thereof, such Grantor shall
        report such filing to the Trustee and the Noteholders within five
        Business Days after the last day of the calendar year in which such
        filing occurs (or, if the Trustee reasonably so requests in writing,
        more often).  Upon request of the Trustee, each Grantor shall execute
        and deliver any and all agreements, instruments, documents, and papers
        as the Trustee may reasonably request to evidence the Trustee's
        security interest (for the benefit of the Trustee and the Noteholders)
        in any Patent and the Goodwill, Proceeds and General Intangibles, if
        any, of such Grantor relating thereto or represented thereby, and each
        Grantor hereby constitutes the Trustee its attorney-in-fact to execute
        and file all such writings for the purposes of so evidencing the
        Trustee's security interest (and the Trustee agrees to notify each
        Grantor that any such filing has been made, provided that any failure
        to so notify shall not invalidate any such actions by the Trustee),
        all lawful acts of such attorney-in-fact being hereby ratified and
        confirmed; such power being coupled with an interest is irrevocable
        until the Obligations are paid in full and have been terminated.

                  (4)     Each Grantor will, except with respect to any Patent
        application or registration that is not material to the business of
        the Company and its Subsidiaries, taken as a whole, take all
        reasonable and necessary steps, as it shall deem appropriate under the
        circumstances, in accordance with its reasonable business judgment,
        including, without limitation, in any proceeding before the PTO, or
        any

                                       5
<PAGE>

        similar office or agency in any other country or any political
        subdivision thereof, to maintain and pursue each Patent application
        (and to obtain the relevant registration and to maintain such
        registration), including, without limitation, where appropriate filing
        of applications for renewal, affidavits of use and affidavits of
        incontestability.

                  (5)     In the event that any Patent included in the
        Collateral is materially infringed or misappropriated, each Grantor
        shall promptly notify the Trustee after it learns thereof and shall,
        unless each Grantor shall reasonably determine that such Patent is not
        of material economic value to each Grantor, take such actions as such
        Grantor shall reasonably deem appropriate under the circumstances to
        protect such Patent.

          5.     Limitation on Duties Regarding; Preservation of Collateral.
The Trustee's sole duty with respect to the custody, safekeeping and physical
preservation of the Collateral in its possession, under Section 9-207 of the
Code or otherwise, shall be to deal with it in the same manner as the Trustee
deals with similar property for its own account.  Neither the Trustee, any
Noteholder, nor any of their respective directors, officers, employees or
agents shall be liable for failure to demand, collect or realize upon all or
any part of the Collateral or for any delay in doing so or shall be under any
obligation to sell or otherwise dispose of any Collateral upon the request of
any Grantor or any other Person.

          6.     Severability.  Any provision of this Patent Security
Agreement that is prohibited or unenforceable in any jurisdiction shall, as to
such jurisdiction, be ineffective to the extent of such prohibition or
unenforceability without invalidating the remaining provisions hereof, and any
such prohibition or unenforceability in any jurisdiction shall not invalidate
or render unenforceable such provision in any other jurisdiction.

          7.     Section Headings.  The section and subsection headings used
in this Patent Security Agreement are for convenience of reference only and
are not to affect the construction hereof or be taken into consideration in
the interpretation hereof.

          8.     No Subrogation.  Notwithstanding anything to the contrary in
this Patent Security Agreement, each Grantor hereby irrevocably waives all
rights which may have arisen in connection with this Patent Security Agreement
to be subrogated to any of the rights (whether contractual, under the
Bankruptcy Code, including Section 509 thereof, under common law or otherwise)
of the Trustee or the Noteholders against the Company or against any
collateral security or guarantee or right of offset held by the Trustee or the
Noteholders for the payment of the Obligations until all amounts owing to the
Trustee and the Noteholders on account of the Obligations are paid in full and
have been terminated.  Each Grantor hereby further irrevocably waives all
contractual, common law, statutory or other rights of reimbursement,
contribution, exoneration or indemnity (or any similar right) from or against
the Company or any other Person which may have arisen in connection with this
Patent Security Agreement until all amounts owing to the Trustee and the
Noteholders on account of the Obligations are paid in full and have been
terminated.  So long as the Obligations remain outstanding, if any amount
shall be paid on or on behalf of the Company to any Grantor on account of any
of the rights waived in this Section 8, such amount shall be held by such
Grantor in trust, segregated from other funds of such Grantor, and shall,
forthwith upon receipt by such Grantor, be turned over to the Trustee for the
benefit of the Trustee and the

                                       6
<PAGE>

Noteholders in the exact form received by such Grantor (duly endorsed by each
Grantor to the Trustee, if required), to be applied against the Obligations,
whether matured or unmatured, in such order as the Trustee may determine.

          9.     Amendments in Writing;  No Waiver; Cumulative Remedies.  (a)
None of the terms or provisions of this Patent Security Agreement may be
waived, amended, supplemented or otherwise modified except by a written
instrument executed by each Grantor and the Trustee, provided that any
provision of this Patent Security Agreement may be waived by the Trustee and
the Noteholders in a letter or agreement executed by the Trustee or by telex
or facsimile transmission from the Trustee.

               (b)     Neither the Trustee nor any Noteholder shall by any act
(except by a written instrument pursuant to paragraph 9(a) hereof), delay,
indulgence, omission or otherwise be deemed to have waived any right or remedy
hereunder or to have acquiesced in any Default or Event of Default or in any
breach of any of the terms and conditions hereof. No failure to exercise, nor
any delay in exercising, on the part of the Trustee or any Noteholder, any
right, power or privilege hereunder shall operate as a waiver thereof. No
single or partial exercise of any right, power or privilege hereunder shall
preclude any other or further exercise thereof or the exercise of any other
right, power or privilege. A waiver by the Trustee or any Noteholder of any
right or remedy hereunder on any one occasion shall not be construed as a bar
to any right or remedy which the Trustee or such Noteholder would otherwise
have on any future occasion.

               (c)     The rights and remedies herein provided are cumulative,
may be exercised singly or concurrently and are not exclusive of any other
rights or remedies provided by law.

          10.     Notices.  All notices, requests and demands to or upon the
Trustee or any Grantor to be effective shall be in writing (or by telex, fax
or similar electronic transfer confirmed in writing) and shall be deemed to
have been duly given or made (1) when delivered by hand; (2) if given by mail,
three days after deposited in the mails by certified mail, return receipt
requested, postage prepaid or (3) if by telex, fax or similar electronic
transfer, when sent and receipt has been confirmed, addressed as follows:

                  (1)     if to the Trustee, at its address or transmission
        number for notices provided in Section 13.02 of the Indenture; and

                  (2)     if to a Grantor, at the address or transmission
        number for notices to the Company as provided in Section 13.02 of the
        Indenture.

The Trustee and each Grantor may change their addresses and transmission
numbers for notices by notice in the manner provided in this Section 13.02 of
the Indenture.

          11.     Successors and Assigns.  This Patent Security Agreement
shall be binding upon the successors and assigns of each Grantor and shall
inure to the benefit of the Trustee and the Noteholders and their successors
and assigns.

                                       7
<PAGE>

          12.     Submission To Jurisdiction; Waivers.  Each Grantor hereby
irrevocably and unconditionally:

                  (1)     submits for itself and its property in any legal
        action or proceeding relating to this Patent Security Agreement, the
        Subsidiaries' Security Agreement and the other Collateral Documents to
        which it is a party, or for recognition and enforcement of any
        judgment in respect thereof, to the non-exclusive general jurisdiction
        of the courts of the State of New York, the courts of the United
        States of America for the Southern District of New York, and appellate
        courts from any thereof;

                  (2)     consents that any such action or proceeding may be
        brought in such courts and waives any objection that it may now or
        hereafter have to the venue of any such action or proceeding in any
        such court or that such action or proceeding was brought in an
        inconvenient court and agrees not to plead or claim the same;

                  (3)     agrees that service of process in any such action or
        proceeding may be effected by mailing a copy thereof by registered or
        certified mail (or any substantially similar form of mail), postage
        prepaid, to each Grantor at its address set forth in Section 13.02 of
        the Indenture or at such other address of which the Trustee shall have
        been notified pursuant thereto;

                  (4)     agrees that nothing herein shall affect the right to
        effect service of process in any other manner permitted by law or
        shall limit the right to sue in any other jurisdiction; and

                  (5)     waives, to the maximum extent not prohibited by law,
        any right it may have to claim or recover in any legal action or
        proceeding referred to in this Section any special, exemplary,
        punitive or consequential damages.

          13.     Acknowledgments.  Each Grantor hereby acknowledges that:

                  (1)     it has been advised by counsel in the negotiation,
        execution and delivery of this Patent Security Agreement, the
        Subsidiaries' Security Agreement and the other Collateral Documents to
        which it is a party;

                  (2)     neither the Trustee nor any Noteholder has any
        fiduciary relationship with or duty to it or any other RBX Party
        arising out of or in connection with this Patent Security Agreement,
        the Subsidiaries' Security Agreement or any of the other Collateral
        Documents, and the relationship between the Trustee and Noteholders,
        on one hand, and the RBX Parties, on the other hand, in connection
        herewith or therewith is solely that of debtor and creditor; and

                  (3)     no joint venture is created hereby or by the other
        Collateral Documents or otherwise exists by virtue of the transactions
        contemplated hereby among the Noteholders, the Trustee or the RBX
        Parties.

                                       8
<PAGE>

          14.     WAIVER OF JURY TRIAL.  EACH GRANTOR HEREBY IRREVOCABLY AND
UNCONDITIONALLY WAIVES TRIAL BY JURY IN ANY LEGAL ACTION OR PROCEEDING
RELATING TO THIS PATENT SECURITY AGREEMENT OR ANY OTHER COLLATERAL DOCUMENT
AND FOR ANY COUNTERCLAIM THEREIN.


          15.     GOVERNING LAW.  THIS PATENT SECURITY AGREEMENT SHALL BE
GOVERNED BY, AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE
STATE OF NEW YORK WITHOUT REGARD TO CONFLICTS OF LAWS PROVISIONS THEREOF.

          16.     Authority of Trustee.  Each Grantor acknowledges that the
rights and responsibilities of the Trustee under this Patent Security
Agreement with respect to any action taken by the Trustee or the exercise or
non-exercise by the Trustee of any option, right, request, judgment or other
right or remedy provided for herein or resulting or arising out of this Patent
Security Agreement shall, as between the Trustee and the Noteholders, be
governed by the Indenture, but, as between the Trustee and each Grantor, the
Trustee shall be conclusively presumed to be acting as agent for the
Noteholders with full and valid authority so to act or refrain from acting,
and each Grantor shall not be under any obligation, or entitlement, to make
any inquiry respecting such authority.

          17.     Incorporation of Subsidiaries' Security Agreement
Provisions.  Each Grantor hereby acknowledges and affirms that the rights and
remedies of the Trustee with respect to the security interest in the
Collateral made and granted hereby are more fully set forth in the
Subsidiaries' Security Agreement, the terms and provisions of which are
incorporated by reference herein as if fully set forth herein.  Nothing in
this Patent Security Agreement shall defer or impair any attachment or
perfection of any security interest in the collateral covered by the
Subsidiaries' Security Agreement which would attach or be perfected pursuant
to the terms thereof without action by such Grantor or any other Person.

          18.     Release of Collateral and Termination.

                  (1)     Upon the payment in full or Legal Defeasance of all
        principal of, interest on, premium, if any, and Liquidated Damages, if
        any, with respect to the Notes and all Obligations for the payment of
        money then due and owing to any Noteholder or the Trustee under the
        Indenture and the Collateral Documents, the Collateral shall be
        released from the Liens created hereby, and this Patent Security
        Agreement and all obligations (other than those expressly stated to
        survive such termination) of the Trustee and each Grantor hereunder
        shall terminate, all without delivery of any instrument or performance
        of any act by any party, and all rights to the Collateral shall revert
        to each Grantor.  Upon request of any Grantor following any such
        termination, the Trustee shall deliver (at the sole cost and expense
        of such Grantor) to each Grantor any Collateral held by the Trustee
        hereunder, and execute and deliver (at the sole cost and expense of
        such Grantor) to such Grantor such documents as such Grantor shall
        reasonably request to evidence such termination.

                                       9
<PAGE>

                  (2)     If any of the Collateral shall be sold, transferred
        or otherwise disposed of by any Grantor in a transaction permitted by
        the Indenture, then the Trustee shall execute and deliver to such
        Grantor (at the sole cost and expense of such Grantor) all releases.
        termination statements or other documents reasonably necessary for the
        release of the Liens created hereby on such Collateral.

          19.     Contradictory Provisions.  In the event any one or more of
the provisions of this Patent Security Agreement shall be found in a final
judgment of any New York State court or Federal court of the United States of
America sitting in New York City, and any appellate court from any thereof, to
contradict or otherwise limit any provision in the Indenture, the provision in
the Indenture shall control.

                                       10
<PAGE>

          IN WITNESS WHEREOF, the undersigned have caused this Patent Security
Agreement to be duly executed and delivered as of the date first above
written.

                                  GROENDYK MANUFACTURING COMPANY, INC.

                                  By:     /s/ John C. Cantlin
                                     ---------------------------------
                                  Name:   John C. Cantlin
                                  Title:  Chief Financial Officer


                                  HOOVER-HANES RUBBER CUSTOM MIXING CORP.


                                  By:     /s/ John C. Cantlin
                                     ---------------------------------
                                  Name:   John C. Cantlin
                                  Title:  Chief Financial Officer


                                  MIDWEST RUBBER CUSTOM MIXING CORP.


                                  By:     /s/ John C. Cantlin
                                     ---------------------------------
                                  Name:   John C. Cantlin
                                  Title:  Chief Financial Officer


                                  OLETEX INC.


                                  By:     /s/ John C. Cantlin
                                     ---------------------------------
                                  Name:   John C. Cantlin
                                  Title:  Chief Financial Officer


                                  RUBATEX CORPORATION


                                  By:     /s/ John C. Cantlin
                                     ---------------------------------
                                  Name:   John C. Cantlin
                                  Title:  Chief Financial Officer


                                  UNIVERSAL POLYMER & RUBBER INC.

                                       11
<PAGE>

                                  By:     /s/ John C. Cantlin
                                     ---------------------------------
                                  Name:   John C. Cantlin
                                  Title:  Chief Financial Officer

                                       12
<PAGE>

                                  UNIVERSAL RUBBER COMPANY


                                  By:     /s/ John C. Cantlin
                                     ---------------------------------
                                  Name:   John C. Cantlin
                                  Title:  Chief Financial Officer


                                  WALTEX CORPORATION


                                  By:     /s/ John C. Cantlin
                                     ---------------------------------
                                  Name:   John C. Cantlin
                                  Title:  Chief Financial Officer

                                       13
<PAGE>

[NAME OF GRANTOR]

 STATE OF                 )
                          )  ss.:
 COUNTY OF                )

          On the [] day of December, 1997 before me personally came
______________, ___________________, to me personally known and known to me to
be the person described in and who executed the foregoing instrument as
_________ of ________________________, who, being by me duly sworn, did depose
and say that he resides at ____________________; that he is _________ of
_________________________, one of the corporations described in and which
executed the foregoing instrument; that he knows the seal of said corporation:
that the seal affixed to said instrument is such corporate seal; that said
instrument was signed and sealed on behalf of said corporation by order of its
Board of Directors; that he signed his name thereto by like order; and that he
acknowledged said instrument to be the free act and deed of said corporation.



                                   ---------------------------------------
                                   Name:


[NOTARIAL SEAL]

                                       14
<PAGE>

                                                                 Schedule 1
                                               to Patent Security Agreement
                                               ----------------------------


                          PATENT AND PATENT LICENSES
                          --------------------------


                               DOMESTIC PATENTS
                               ----------------


U.S. PATENT NO.
OWNER                             PATENT
---------------                   ------
4,976,902                         Molding Method
Rubatex Corporation

4,479,269                         Athletic Padding
Rubatex Corporation

4,602,792                         Dual Function Gasket
Universal Polymer & Rubber Inc.

4,602,793                         Gasket with Locking Ring
Universal Polymer & Rubber Inc.

D,300,404                         Telescopically Extendible
Rubatex Corporation
                                  Hole Cutter


                               FOREIGN PATENTS
                               ---------------
                                     None


                               PATENT LICENSES
                               ---------------
                                     None

                                      S-1
<PAGE>

                                                                 Schedule A
                                               to Patent Security Agreement
                                               ----------------------------

                                   GRANTORS
                                   --------


Groendyk Manufacturing Company, Inc.
Hoover-Hanes Rubber Custom Mixing Corp.
Midwest Rubber Custom Mixing Corp.
OleTex Inc.
Rubatex Corporation
Universal Polymer & Rubber Inc.
Universal Rubber Company
Waltex Corporation

                                      S-2