<PAGE>   1
                                                                   Exhibit 10.19

                                    SUPPLEMENT NO. 1, dated as of July 19, 2001,
                                    to the PLEDGE AGREEMENT dated as of
                                    September 30, 1997, as amended and restated
                                    as of May 31, 2000, among PLIANT CORPORATION
                                    (f/k/a Huntsman Packaging Corporation), a
                                    Utah corporation (the "Borrower"), and each
                                    subsidiary of the Borrower listed on
                                    Schedule I thereto (each such subsidiary
                                    individually a "Subsidiary Pledgor" and
                                    collectively, the "Subsidiary Pledgors"; the
                                    Borrower and the Subsidiary Pledgors are
                                    referred to collectively herein as the
                                    "Pledgors") and BANKERS TRUST COMPANY, a New
                                    York banking corporation ("Bankers Trust"),
                                    as collateral agent (in such capacity, the
                                    "Collateral Agent") for the Secured Parties
                                    (as defined in the Credit Agreement referred
                                    to below)

         A. Reference is made to (a) the Credit Agreement dated as of September
30, 1997, as amended and restated as of May 31, 2000 (as amended, supplemented
or otherwise modified from time to time, the "Credit Agreement"), among the
Borrower, the lenders from time to time party thereto (the "Lenders"), Aspen
Industrial, S.A. de C.V., a Mexico corporation, and Bankers Trust, as
administrative agent (in such capacity, the "Administrative Agent") for the
Lenders and (b) the Guarantee Agreement dated as of September 30, 1997, as
amended and restated as of May 31, 2000 (as amended, supplemented or otherwise
modified from time to time, the "Guarantee Agreement"), among the Borrower, the
Subsidiary Pledgors and the Collateral Agent.

         B. Capitalized terms used herein and not otherwise defined herein shall
have the meanings assigned to such terms in the Credit Agreement.

         C. The Pledgors have entered into the Pledge Agreement in order to
induce the Lenders to make Loans and the Issuing Bank to issue Letters of
Credit. Pursuant to Section 5.12 of the Credit Agreement, each Subsidiary Loan
Party that was not in existence or not a Subsidiary Loan Party on the date of
the Credit Agreement is required to enter into the Pledge Agreement as a
Subsidiary Pledgor upon becoming a Subsidiary Loan Party. Section 24 of the
Pledge Agreement provides that such Subsidiaries may become Subsidiary Pledgors
under the Pledge Agreement by execution and delivery of an instrument in the
form of this Supplement. Each of the undersigned Subsidiaries (the "New
Pledgors") is executing this Supplement in accordance with the requirements of
the Credit Agreement to become a Subsidiary Pledgor under the Pledge Agreement
in order to induce the Lenders to make additional Loans and the Issuing Bank to
issue additional Letters of Credit and as consideration for Loans previously
made and Letters of Credit previously issued.

         Accordingly, the Collateral Agent and each of the New Pledgors agree as
follows:

         SECTION 1. In accordance with Section 24 of the Pledge Agreement, each
of the New Pledgors by its signature below becomes a Pledgor under the Pledge
Agreement with the same force and effect as if originally named therein as a
Pledgor and each of the New Pledgors hereby agrees (a) to all the terms and
provisions of the Pledge Agreement applicable to it as a Pledgor


<PAGE>   2
thereunder and (b) represents and warrants that the representations and
warranties made by it as a Pledgor thereunder are true and correct on and as of
the date hereof. In furtherance of the foregoing, each of the New Pledgors, as
security for the payment and performance in full of the Obligations (as defined
in the Pledge Agreement), does hereby create and grant to the Collateral Agent,
its successors and assigns, for the benefit of the Secured Parties, their
successors and assigns, a security interest in and lien on all of such New
Pledgor's right, title and interest in and to the Collateral (as defined in the
Pledge Agreement) of such New Pledgor. Each reference to a "Subsidiary Pledgor"
or a "Pledgor" in the Pledge Agreement shall be deemed to include the New
Pledgors. The Pledge Agreement is hereby incorporated herein by reference.

         SECTION 2. Each of the New Pledgors represents and warrants to the
Collateral Agent and the other Secured Parties that this Supplement has been
duly authorized, executed and delivered by it and constitutes its legal, valid
and binding obligation, enforceable against it in accordance with its terms.

         SECTION 3. This Supplement may be executed in counterparts, each of
which shall constitute an original, but all of which when taken together shall
constitute a single contract. This Supplement shall become effective when the
Collateral Agent shall have received counterparts of this Supplement that, when
taken together, bear the signatures of each of the New Pledgors and the
Collateral Agent. Delivery of an executed signature page to this Supplement by
facsimile transmission shall be as effective as delivery of a manually signed
counterpart of this Supplement.

         SECTION 4. Each of the New Pledgors hereby represents and warrants that
set forth on Schedule I attached hereto is a true and correct schedule of all
its Pledged Securities.

         SECTION 5. Except as expressly supplemented hereby, the Pledge
Agreement shall remain in full force and effect.

         SECTION 6. THIS SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

         SECTION 7. In case any one or more of the provisions contained in this
Supplement should be held invalid, illegal or unenforceable in any respect, no
party hereto shall be required to comply with such provision for so long as such
provision is held to be invalid, illegal or unenforceable, but the validity,
legality and enforceability of the remaining provisions contained herein and in
the Pledge Agreement shall not in any way be affected or impaired. The parties
hereto shall endeavor in good-faith negotiations to replace the invalid, illegal
or unenforceable provisions with valid provisions the economic effect of which
comes as close as possible to that of the invalid, illegal or unenforceable
provisions.

         SECTION 8. All communications and notices hereunder shall be in writing
and given as provided in Section 15 of the Pledge Agreement. All communications
and notices hereunder to each of the New Pledgors shall be given to it at the
address set forth under its signature hereto.
<PAGE>   3
         SECTION 9. Each of the New Pledgors agrees to reimburse the Collateral
Agent for its reasonable out-of-pocket expenses in connection with this
Supplement, including the reasonable fees, other charges and disbursements of
counsel for the Collateral Agent.
<PAGE>   4
IN WITNESS WHEREOF, each of the New Pledgors and the Collateral Agent have duly
executed this Supplement to the Pledge Agreement as of the day and year first
above written.


                                        UNIPLAST HOLDINGS INC.,

                                        By    /s/ Larry Shepler
                                          --------------------------------------
                                        Name:     Larry Shepler
                                        Title:    Secretary
                                        Address:  c/o Pliant Corporation
                                                  1515 Woodfield Road, Suite 600
                                                  Schaumburg, Illinois 60173


                                        UNIPLAST U.S., INC.,

                                        By    /s/ Larry Shepler
                                          --------------------------------------
                                        Name:     Larry Shepler
                                        Title:    Secretary
                                        Address:  c/o Pliant Corporation
                                                  1515 Woodfield Road, Suite 600
                                                  Schaumburg, Illinois 60173


                                        TUREX, INC.,

                                        By    /s/ Larry Shepler
                                          --------------------------------------
                                        Name:     Larry Shepler
                                        Title:    Secretary
                                        Address:  c/o Pliant Corporation
                                                  1515 Woodfield Road, Suite 600
                                                  Schaumburg, Illinois 60173

                                        PIERSON INDUSTRIES, INC.,

                                        By    /s/ Larry Shepler
                                          --------------------------------------
                                        Name:     Larry Shepler
                                        Title:    Secretary
                                        Address:  c/o Pliant Corporation
                                                  1515 Woodfield Road, Suite 600
                                                  Schaumburg, Illinois 60173
<PAGE>   5
                                        UNIPLAST MIDWEST, INC.,

                                        By    /s/ Larry Shepler
                                          --------------------------------------
                                        Name:     Larry Shepler
                                        Title:    Secretary
                                        Address:  c/o Pliant Corporation
                                                  1515 Woodfield Road, Suite 600
                                                  Schaumburg, Illinois 60173


                                        BANKERS TRUST COMPANY,
                                        as Collateral Agent,

                                        By     /s/ Robert R. Telesca
                                           -------------------------------------
                                        Name:     Robert R. Telesca
                                        Title:    Vice President
                                        Address:  One Bankers Trust Plaza
                                                  New York, New York 10006
<PAGE>   6
                                                                      Schedule I
                                                             to Supplement No. 1
                                                         to the Pledge Agreement

UNIPLAST HOLDINGS INC.

                                  CAPITAL STOCK

<TABLE>
<CAPTION>
<S>                       <C>                 <C>                     <C>                    <C>
                                                                      Number and
                          Number of           Registered              Class of               Percentage
Issuer                    Certificate         Owner                   Shares                 of Shares
------                    -----------         -----                   ------                 ---------


Uniplast U.S., Inc.       Blank               Uniplast                1,000 shares of        100% of
                                              Holdings Inc.           common stock           common stock

Uniplast Industries Co.                       Uniplast                997,480 shares of      100%(1)
                                              Holdings Inc.           common stock
</TABLE>




                                 DEBT SECURITIES

<TABLE>
<CAPTION>
<S>                      <C>                          <C>              <C>
Issuer                   Principal Amount             Date of Note     Maturity Date
------                   ----------------             ------------     -------------
Uniplast Industries Co.  $8,505,044.01                07/16/01         Demand

</TABLE>

--------

(1) The pledge of shares of Uniplast Industries Co. is limited to 65% of the
outstanding shares of common stock of Uniplast Industries Co.
<PAGE>   7
UNIPLAST U.S., INC.

                                  CAPITAL STOCK

<TABLE>
<CAPTION>
                                                                             Number and
                             Number of               Registered              Class of               Percentage
Issuer                       Certificate             Owner                   Shares                 of Shares
------                       -----------             -----                   ------                 ---------

<S>                          <C>                     <C>                     <C>                    <C>
Pierson Industries, Inc.    5                        Uniplast U.S., Inc.     12,500 shares of       100%
                                                                             common stock

Turex, Inc.                 23                       Uniplast U.S., Inc.     61 shares of common    100%
                                                                             stock

Uniplast Midwest, Inc.      3                        Uniplast U.S., Inc.     1,000 shares of        100%
                                                                             common stock
</TABLE>