<PAGE>

                                                           EXHIBIT 4.15

                      COMPANY PATENT SECURITY AGREEMENT

          COMPANY PATENT SECURITY AGREEMENT, made by RBX CORPORATION, a
Delaware corporation (the "Company"), in favor of STATE STREET BANK AND TRUST
COMPANY, a Massachusetts trust company, as trustee (in such capacity, the
"Trustee") for the 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 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 the Company shall
have executed and delivered the Company Security Agreement of even date
herewith (as amended, supplemented or otherwise modified from time to time,
the "Company Security Agreement") to the Trustee for the benefit of the
Trustee and the Noteholders;

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

          WHEREAS, pursuant to the terms of the Company Security Agreement,
the Company has 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 the Company 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 Company Security Agreement, the
parties hereto have entered into this Patent Security Agreement; and

          WHEREAS, it is a further requirement of the Indenture that the
Company 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, the Company hereby
agrees with the Trustee, for the benefit of the Trustee and the Noteholders,
as follows:

          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, Equipment, General Intangibles, Inventory
and Proceeds.

          (b)     The following terms shall have the following meanings:
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          "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 or 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 "Company 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 the Company 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."

          "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
<PAGE>

          2.     Security Interest.

                  (a)     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, the Company 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 the Company or in which the Company 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.

                  (b)     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 the Company or the Subsidiary Guarantors with respect to
        or arising out of the Collateral.

          3.     Representations and Warranties.  The Company hereby
represents and warrants that:

                  (a)     Patents.  Schedule 1 hereto includes all registered
        U.S. Patents owned by the Company on the date hereof and all other
        Patents and Patent Licenses owned by the Company 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 the Company'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 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.

                                       3
<PAGE>

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

          4.     Covenants.  The Company covenants and agrees with the Trustee
and the Noteholders that, from and after the date of this Patent Security
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:

                  (a)     Further Documentation.  At any time and from time to
        time, upon the written request of the Trustee, and at the sole expense
        of the Company, the Company 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 of
        the rights and powers herein granted.

                  (b)     Indemnification.

                          (1)     The Company agrees to pay, and to save the
                Trustee and the Noteholders harmless from, any and all
                liabilities, costs and expenses (including, without
                limitation, reasonable legal fees and expenses) (i) with
                respect to, or resulting from, any delay or failure by the
                Company in paying any and all excise, sales or other taxes
                which may be payable or determined to be payable with respect
                to any of the Collateral, (ii) with respect to, or resulting
                from, any delay in complying or failure to comply with any
                Requirement of Law applicable to any of the Collateral or
                (iii) 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 sum
                owing thereunder, the Company 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 the Company 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 the Company.  The Trustee may
                have separate counsel and the company shall pay the reasonable
                fees and expenses of such counsel.  The Company 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 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.

                                       4
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                  (c)     Patents.

                          (1)     The Company will not (either itself or
                though licensees), except with respect to any Patent that the
                Company 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)     The Company 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 the Company does not own all
                right, 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) the Company 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 the Company, either by itself or
                through any agent, employee, licensee or designee, shall file
                an application for the registration of a patent with the
                Untied States Patent and Trademark Office (the "PTO") or any
                similar office or agency in any other country or any political
                subdivision thereof, the Company 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,
                at such other times). Upon request of the Trustee, the Company
                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 the
                Company relating thereto or represented thereby, and the
                Company 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 the Company 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)     The Company 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 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

                                       5
<PAGE>

                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, the
                Company shall promptly notify the Trustee after it learns
                thereof and shall, unless the Company shall reasonably
                determine that such Patent is not of material economic value
                to the Company, take such actions as the Company 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
the Company or any other Person.

          6.     Severability.  Any provision of this Patent Security
Agreement which 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.     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 the Company 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 8(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

                                       6
<PAGE>

        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.

          9.     Notices.  All notices, requests and demands to or upon the
Trustee or the Company 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 or (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:

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

                  (b)     if to the Company, at its address or transmission
        number for notices provided in Section 13.02 of the Indenture.

The Trustee and the Company may change their addresses and transmission
numbers for notices by notice in the manner provided in this Section.

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

          11.     Submission To Jurisdiction; Waivers.  The Company hereby
irrevocably and unconditionally:

                  (a)     submits for itself and its property in any legal
        action or proceeding relating to this Patent Security Agreement, the
        Company 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;

                  (b)     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;

                  (c)     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 the Company at its address set forth in Section 13.02 of

                                       7
<PAGE>

        the Indenture or at such other address of which the Trustee shall have
        been notified pursuant thereto;

                  (d)     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

                  (e)     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 11 any special, exemplary,
        punitive or consequential damages.

          12.     Acknowledgments.  The Company hereby acknowledges that:

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

                  (b)     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 Company 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

                  (c)     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.

          13.     WAIVER OF JURY TRIAL.  THE COMPANY 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.

          14.     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.

          15.     Authority of Trustee.  The Company 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 the Company, 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 the

                                       8
<PAGE>

Company shall not be under any obligation, or entitlement, to make any inquiry
respecting such authority.

          16.     Incorporation of Company Security Agreement Provisions.  The
Company 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 Company 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 or any security interest in the Collateral
covered by the Company Security Agreement that would attach or be perfected
pursuant to the terms thereof without action by the Company or any other
Person.

          17.     Release of Collateral and Termination.  (a) 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 any other
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 the Company 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 the Company. Upon request of
the Company following any such termination, the Trustee shall deliver (at the
sole cost and expense of the Company) to the Company any Collateral held by
the Trustee hereunder, and execute and deliver (at the sole cost and expense
of the Company) to the Company such documents as the Company shall reasonably
request to evidence such termination.

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

          18.     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.

                                       9
<PAGE>

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

RBX CORPORATION



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

                                       10
<PAGE>

                               RBX CORPORATION


STATE OF                         )
                                   : ss.:
COUNTY OF                        )




          On the 11th 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 instruments as __________________
of ___________________ ________________________, who, being by me duly sworn,
did depose and 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]

                                       11
<PAGE>

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


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

                                     None

                                       1