<PAGE>
 
                                                                     EXHIBIT 2.3
                                                                                
                           STOCK PURCHASE AGREEMENT
                                        

     This Stock Purchase Agreement (this "Agreement") dated as of September 10,
1998, is by and among IMPAC Group, Inc., a Delaware corporation (the "Company");
and each of the Investors listed in column 1 of Schedule 1 hereto (the
"Investors", and each individually, an "Investor").

     Concurrently with the execution and delivery of this Agreement, the
Company's subsidiary, IMPAC Europe PLC, an English public limited company
("IMPAC Europe") will complete the purchase (the "Acquisition") of a majority of
the outstanding share capital of Tinsley Robor plc, an English public limited
company ("Tinsley Robor"), pursuant to and in accordance with the Recommended
Cash Offer, dated July 22, 1997, made by BT Wolfensohn on behalf of IMPAC Europe
for the whole of the issued share capital of Tinsley Robor (the "Offer
Announcement").

     The parties desire that the Investors, in exchange for the investments
described herein which are to be used to partially finance completion of the
Acquisition, receive certain shares of the Company's Series A Common Stock (as
defined herein).

     Accordingly, subject to the terms and conditions herein and based upon the
respective representations and warranties set forth below, the parties hereto
hereby agree as follows:

     1.   Definitions.

     1.1. Certain Defined Terms.  As used in this Agreement, the following terms
have the following respective meanings:

     "Affiliate" means, with respect to a specified Person, (i) any Person that
directly, or indirectly through one or more intermediaries, controls or is
controlled by, or is under common control with, the specified Person and (ii)
any Person that is an officer, director, trustee, member or general partner of,
or serves in a similar capacity with respect to, the specified Person, or of
which the specified Person is an officer, director, trustee, member or general
partner, or with respect to which the specified Person serves in a similar
capacity or (iii) any Person who is a spouse, parent, sibling or lineal
descendant of such Person or any Person described in clauses (i) or (ii).  For
purposes of this definition the term "control" when used with respect to a
Person means (a) the beneficial ownership (as defined in Rule 13d-d promulgated
under the Securities Exchange Act of 1934, as
<PAGE>
 
                                      -2-

amended) of 50 percent or more of the voting interests in such Person, or (b)
the possession, direct or indirect, of the power to direct or cause the
direction of the management and policies of such Person, whether through the
ownership of voting securities, by contract or otherwise.

     "Amended and Restated Stockholder Agreement" means that certain First
Amended and Restated Stockholder Agreement of the Company in the form attached
hereto as Exhibit A, among the Company and each of its stockholders (after
giving effect to the purchase of shares described herein), dated as of March 12,
1998, and amended and restated as of the Closing Date, as amended and in effect
from time to time.

     "BofA Credit Agreement" means the Amended and Restated Multicurrency Credit
Agreement, dated as of March 12, 1998, and as amended and restated as of July 7,
1998, by and among the Company, certain of its Subsidiaries, the Lenders
referred to therein, and Bank of America National Trust and Savings Association,
as Agent, Letter of Credit Issuing Bank and Swing Line Lender, as amended and in
effect from time to time.

     "Equity Recapitalization Agreement" means the letter agreement in the form
attached hereto as Exhibit B, dated as of the Closing Date, among the Company
and each of its stockholders (after giving effect to the purchase of shares
described herein), with respect to a proposed equity recapitalization of the
Company.

     "Existing Stockholder Agreement" means the Stockholder Agreement of the
Company, among the Company and each of its stockholders, dated as of March 12,
1998.

     "Heritage Funds" means Heritage Fund I, L.P., and Heritage Fund II, L.P.,
together, each a Delaware limited partnership, and individually a "Heritage
Fund".

     "Indebtedness", as applied to any Person, means (a) all indebtedness of
such Person for borrowed money, whether current or funded, or secured or
unsecured, (b) all indebtedness of such Person for the deferred purchase price
of property or services represented by a note or other security, (c) all
indebtedness of such Person created or arising under any conditional sale or
other title retention agreement (even if the rights and remedies of the seller
or lender under such agreement in the event of default are limited to
repossession or sale of specific property), (d) all indebtedness of such Person
secured by a purchase money mortgage or other Lien to secure all or part of the
purchase price of property subject to such mortgage or other Lien, (e) all
obligations of such Person under leases that have been or must be, in accordance
with generally accepted accounting principles, recorded as capital leases in
respect of which such Person is liable as lessee, (f) any liability of such
Person in respect of banker's acceptances or letters of credit, and (g) all
indebtedness referred to in clauses (a), (b), (c), (d), (e), or (f) above that
is directly or indirectly guaranteed by such Person or which such Person has
agreed (contingently or otherwise) to purchase or otherwise acquire or in
respect of which such Person has otherwise assured a creditor against loss.
<PAGE>
 
                                      -3-

     "Lien" means any lien, claim, mortgage, security interest, charge,
encumbrance, or restriction on transfer of any kind.

     "Other Agreement(s)" means the Amended and Restated Stockholder Agreement,
the Equity Recapitalization Agreement, and all of the other agreements,
instruments, certificates, and documents executed and delivered at the Closing
or otherwise in connection with this Agreement and/or in connection with the
transactions contemplated hereby, and when used with reference to any particular
Person, means all such agreements, instruments, certificates and other documents
executed and delivered by such Person.

     "Person" means any natural person, entity, or association, including
without limitation any corporation, partnership, limited liability company,
government (or agency or subdivision thereof), trust, joint venture or sole or
joint proprietorship.

     "Repurchase Agreement" means any Employment, Non-Competition and Stock
Repurchase Agreement, Agreement relating to Employment and Stock Ownership,
Stock Purchase Agreement or Stock Repurchase Agreement to which any stockholder
of the Company may from time to time be party, pursuant to which the Company
shall have any right or obligation to repurchase shares of the Company's capital
stock beneficially owned by such stockholder.

     "Series A Common Stock" means the Company's Series A Common Stock, $0.001
par value per share.

     "Subsidiary" or "Subsidiaries" means, with respect to any Person, any
corporation a majority (by number of votes) of the outstanding shares of any
class or classes of the capital stock of which shall at the time be owned by
such Person or by a Subsidiary of such Person, if the holders of the shares of
such class or classes of capital stock (a) are ordinarily, in the absence of
contingencies, entitled to vote for the election of at least a majority of the
directors (or persons performing similar functions) of the issuer thereof,
regardless of whether the right so to vote has been suspended by the happening
of such a contingency, or (b) are at the relevant time of reference entitled, as
such holders, to vote for the election of at least a majority of the directors
(or persons performing similar functions) of the issuer thereof, regardless of
whether the right so to vote exists by reason of the happening of a contingency.
<PAGE>
 
                                      -4-

     1.2.  Terms Defined Elsewhere.  The following terms are defined herein in
the sections identified below:

<TABLE>
<CAPTION>
Term                 Section                 Term                         Section
----                 -------                 ----                         -------
<S>                  <C>                     <C>                          <C> 
Acquisition          Preamble                Holding                      Preamble
Act                  4.2(a)                  IMPAC Europe                 Preamble
Agreement            Preamble                Investor                     Preamble
By-Laws              2.5(a)(ii)(3)(B)        Offer Announcement           Preamble
Closing              2.3                     Purchased Securities         2.1
Closing Date         2.3                     Tinsley Robor                Preamble
</TABLE>

2.   Sale And Purchase of Purchased Securities.

     2.1.  Agreement to Sell and Purchase Purchased Securities.  The Company
hereby agrees to issue and sell to each Investor, and, subject to all of the
terms and conditions hereof and in reliance on the representations and
warranties set forth or referred to herein, each Investor severally agrees to
purchase, the number of shares of Series A Common Stock indicated opposite the
name of such Investor on Schedule 1 hereto (the "Purchased Securities").

     2.2.  Purchase Price.  The purchase price for the Purchased Securities will
be $608.60 per share.

     2.3.  Closing.  The closing of the purchase and sale of the Purchased
Securities (the "Closing") will take place at the offices of Bingham Dana LLP,
150 Federal Street, Boston, Massachusetts  02110, simultaneously with the
execution and delivery of this Agreement, or at such other time, date, and place
as the Company and the Investors may agree (the date on which the Closing
actually occurs, the "Closing Date").

     2.4.  Use of Proceeds.  The Company agrees that the net proceeds from the
sale of the Purchased Securities hereunder, after payment of all fees and
expenses incurred by the Company in connection with the sale of the Purchased
Securities and the other transactions contemplated hereby, will be contributed
and/or loaned by the Company to IMPAC Europe for use by it to finance the
Acquisition of shares of the capital stock of Tinsley Robor pursuant to and in
accordance with the Offer Announcement.

     2.5.  Conditions Precedent.

     (a)  The obligation of the Investors to purchase the Purchased Securities
at the Closing is subject to the fulfillment, or the waiver by each Investor, of
each of the following conditions on or before the Closing:

     (i)  The Company will deliver to each Investor one or more stock
     certificates representing the Purchased Securities to be sold to and
     purchased by such Investor 
<PAGE>
 
                                      -5-

     pursuant to this Agreement, free and clear of all Liens, and registered in
     such Investor's name (or if requested by such Investor, his, her or its
     nominee) in the Company's records.

     (ii)  The Company will deliver to each Investor each of the following
     documents:

          (1)  the Amended and Restated Stockholder Agreement and the Equity
     Recapitalization Agreement, duly executed by the Company and each
     stockholder of the Company other than such Investor;

          (2)  (A) a copy of its charter documents, certified as of a date not
     more than ten business days before the Closing Date, by the Secretary of
     State of the State of Delaware, (B) a certificate of the Secretary of State
     of the State of Delaware, dated as of a date not more than ten business
     days before the Closing Date, with respect to the legal existence, charter
     documents on file with such Secretary of State, and good standing of the
     Company in Delaware, and (C) a certificate of the Secretary of State or
     equivalent official of the States of Illinois and North Carolina and the
     Commonwealth of Pennsylvania, dated not more than ten business days before
     the Closing Date, with respect to the qualification and good standing of
     the Company in such jurisdiction; and

          (3)  a certificate of its Secretary, dated the Closing Date,
     certifying (A) the absence of any amendments to its charter documents (or
     proceedings therefor) since the date of the certificate referred to in
     Section 2.5(a)(ii)(2)(B) above, (B) an attached copy of the Company's
     Amended and Restated By-Laws, (C) the resolutions of its board of directors
     with respect to the transactions hereby contemplated or otherwise to be
     effected at the Closing, and (D) the incumbency of its officers and
     directors.

     (iii)  The representations and warranties of the Company contained in
     Section 3 shall be true on and as of the Closing with the same effect as
     though such representations and warranties had been made on and as of the
     Closing.

     (iv)  The conditions precedent set forth in Section 5.02 of the BofA Credit
     Agreement to the making of the initial "Credit Extensions" thereunder,
     other than the condition precedent set forth in Section 5.02(f) thereof
     requiring completion of the "Equity Investment" referred to therein, shall
     have been either fulfilled or waived in accordance with the BofA Credit
     Agreement.

     (v)  The Offer under and as defined in the Offer Announcement shall have
     become or been declared unconditional in all respects.

     (b)  The obligation of the Company to sell the Purchased Securities at the
Closing is subject to the fulfillment, or the waiver by the Company, of each of
the following conditions on or before the Closing:
<PAGE>
 
                                      -6-

     (i) Each Investor will pay for the Purchased Securities set forth opposite
     such Purchaser's name in Schedule 1 hereto by payment to the Company or its
     nominee of the aggregate purchase price therefor by wire transfer of
     immediately available funds to an account designated in writing by the
     Company prior to the Closing Date.

     (ii) Each Investor will deliver to the Company the Amended and Restated
     Stockholder Agreement and the Equity Recapitalization Agreement duly
     executed by such Investor.

     (iii) The representations and warranties of each Investor contained in
     Section 4 shall be true on and as of the Closing with the same effect as
     though such representations and warranties had been made on and as of the
     Closing.

     (iv) The conditions precedent set forth in Section 5.02 of the BofA Credit
     Agreement to the making of the initial "Credit Extensions" thereunder,
     other than the condition precedent set forth in Section 5.02(f) thereof
     requiring completion of the "Equity Investment" referred to therein, shall
     have been either fulfilled or waived in accordance with the BofA Credit
     Agreement.

     (v) The Offer under and as defined in the Offer Announcement shall have
     become or been declared unconditional in all respects.

     3. Representations and Warranties of the Company.

     In order to induce the Investors to enter into this Agreement and to
purchase the Purchased Securities, the Company hereby represents and warrants to
each of the Investors, both as of the date hereof and as of the Closing Date
(immediately prior to the Closing hereunder), as follows, subject in each case
to such exceptions as are specifically contemplated by this Agreement, or as are
set forth in the Schedules hereto:

     3.1. Incorporation; Authority. The Company is a corporation duly organized,
validly existing, and in good standing under the laws of the State of Delaware,
and has all requisite corporate power and authority to own or lease and operate
its properties and to carry on its business as now conducted.

     3.2. Authorization and Enforceability. The Company has all requisite power
and full legal right and authority (including due approval of its Board of
Directors) to enter into this Agreement, to perform all of its agreements and
obligations under this Agreement in accordance with its terms, and to consummate
the transactions contemplated hereby.  This Agreement has been, or upon
execution and delivery as contemplated hereby, will be, duly executed and
delivered by the Company, and constitutes or will constitute its legal, valid,
and binding obligation, enforceable against it in accordance with 
<PAGE>
 
                                      -7-

its terms, except to the extent that (a) enforcement may be limited by or
subject to any bankruptcy, insolvency, reorganization, moratorium, or similar
laws now or hereafter in effect relating to or limiting creditors' rights
generally, and (b) the remedy of specific performance and injunctive and other
forms of equitable relief are subject to certain equitable defenses and to the
discretion of the court or other similar Person before which any proceeding
therefor may be brought.

     3.3. Capitalization.

     (a) Immediately after the Closing, after giving effect to the sale and
purchase of the Purchased Securities provided for in this Agreement, the
authorized and outstanding capital stock of the Company will be as set forth in
Schedule 2 hereto, and all such outstanding shares of capital stock will be
owned (of record and beneficially) by the Persons and in the amounts there
indicated. All such outstanding shares of capital stock will be duly authorized,
validly issued, fully paid, and nonassessable.

     (b) Except as set forth in the Equity Recapitalization Agreement and in the
Repurchase Agreements, the Company does not have, is not bound by, and has no
obligation to grant or enter into, any (i) outstanding subscriptions, options,
warrants, calls, commitments, or agreements of any character calling for it to
issue, deliver, or sell, or cause to be issued, delivered, or sold, any shares
of its capital stock or any other equity security, or any securities convertible
into, exchangeable for, or representing the right to subscribe for, purchase, or
otherwise acquire any shares of its capital stock or any other equity security,
and (ii) outstanding obligations, contractual or otherwise, to repurchase,
redeem, or otherwise acquire any shares of capital stock or other equity
securities of the Company.

     (c) Except for the Existing Stockholder Agreement, the Amended and Restated
Stockholder Agreement and the Equity Recapitalization Agreement, the Company is
not a party to or bound by, and has no knowledge of, any agreement or instrument
relating to the voting of any of its securities, and is not a party to or bound
by any agreement or instrument under which any Person has the right to require
it to effect, or to include any securities held by such Person in, any
registration under the Act.

     3.4. Lawful Issuance. The Purchased Securities have been offered and at the
Closing will be issued and sold in compliance with all applicable provisions of
the Securities Act and the rules and regulations thereunder, and all applicable
state securities laws and the rules and regulations thereunder.

     3.5. Governmental Consents. No consent, approval or authorization of, or
registration, qualification or filing with, any governmental agency or authority
is required for the execution and delivery by the Company of this Agreement, or
for the consummation by the Company of the transactions contemplated hereby.
<PAGE>
 
                                      -8-

     4. Representations and Warranties of the Investors.

     In order to induce the Company to enter into this Agreement and to issue
and sell its securities as contemplated hereby, each of the Investors severally
and not jointly represents and warrants to the Company, as of the date hereof
and as of the Closing Date, as follows:

     4.1. Authorization and Enforceability. Such Investor, if a legal entity,
has all requisite power and full legal right and authority and if a natural
person, has the legal capacity, competence and power, to enter into this
Agreement and each of the Other Agreements to which such Investor is a party, to
perform all of his, her or its agreements and obligations hereunder and
thereunder, and to consummate the transactions contemplated hereby and thereby.
This Agreement and each of such Other Agreements has been duly executed and
delivered by such Investor and constitutes his, her or its legal, valid, and
binding obligation, enforceable against him, her or it, as the case may be, in
accordance with its respective terms, except to the extent that (a) enforcement
may be limited by or subject to any bankruptcy, insolvency, reorganization,
moratorium, or similar laws now or hereafter in effect relating to or limiting
creditors' rights generally, and (b) the remedy of specific performance and
injunctive and other forms of equitable relief are subject to certain equitable
defenses and to the discretion of the court or other similar Person before which
any proceeding therefor may be brought.

     4.2. Investment Representations.

     (a) Such Investor represents that the Purchased Securities to be acquired
by him, her or it as contemplated hereby shall be acquired for his, her or its
own account, for investment, and not with a view to the distribution thereof.
Such Investor understands that the Purchased Securities have not been registered
under the Securities Act of 1933, as amended (the "Act"), on the ground that the
offer and sale of the Purchased Securities to him, her or it are exempt from the
registration requirements of the Act under Section 4(2) thereof as a transaction
not involving any public offering of such securities. Such Investor understands
that the Company's reliance on such exemption is predicated in part on the
representations of such Investor contained herein.

     (b) Such Investor is an "accredited investor" as defined in Rule 501(a) of
Regulation D promulgated under the Act and has such knowledge and experience in
financial and business matters that he, she or it is capable of evaluating the
merits and risks of the transactions contemplated under this Agreement. Such
Investor's financial condition is such that he, she or it is able to bear all
economic risks of investment in the Purchased Securities, including a complete
loss of the investment therein. Such Investor acknowledges that the Company has
provided such Investor with adequate access to financial and other information
concerning the Company as requested, and such Investor has had the opportunity
to ask questions of and receive answers from the Company concerning the
transactions contemplated by this Agreement and to obtain therefrom any
additional information necessary to make an informed decision regarding an
investment in
<PAGE>
 
                                      -9-

the Company. Such Investor believes that he, she or it has received all the
information such Investor considers necessary or appropriate for deciding
whether to purchase the Purchased Securities. Such Investor is acquiring the
Purchased Securities solely for investment purposes, with no present intention
of distributing or (other than to the limited extent set forth in the Equity
Recapitalization Agreement) reselling any of the Purchased Securities or any
interest therein. Such Investor resides (in the case of an individual) or has
its principal place of business (in the case of any other entity) in the
jurisdiction set forth opposite such Investor's name on Schedule 1 hereto.

     (c) Such Investor understands that he, she or it must bear the economic
risk of his, her or its investment in the Purchased Securities to be acquired by
him, her or it hereunder for an indefinite period of time because such Purchased
Securities have not been registered under the Act, and therefore cannot be sold
unless they are subsequently registered under the Act or an exemption from such
registration is available. Such Investor agrees that he, she or it shall not
offer to sell or otherwise transfer any of the Purchased Securities, in addition
to and without limiting any restrictions or requirements in the Amended and
Restated Stockholder Agreement, except after the Company has received an opinion
of counsel, reasonably acceptable to the Company in form and substance, that
such offer, sale, and/or transfer is not in violation of the registration
requirements of the Act or other applicable law.

     (d) Such Investor acknowledges and agrees that each certificate
representing the Purchased Securities acquired by him, her or it hereunder shall
bear a restrictive legend substantially in the following form:

     "The securities evidenced by this certificate have not been registered
     under the Securities Act of 1933, as amended. No transfer, sale, or other
     disposition of these securities may be made unless a registration statement
     with respect to these shares has become effective under said act, or the
     issuer has been furnished with an opinion of counsel, satisfactory to the
     issuer in form and substance, that such registration is not required."

     (e) Such Investor acknowledges and agrees that the Company shall make a
notation regarding the restrictions on transfer of the Purchased Securities
acquired by such Investor hereunder in the stock books of the Company, and any
purported transfer of such Purchased Securities shall be reflected in the stock
books of the Company only if and when transferred in compliance with all of the
terms and conditions of this Agreement.

     (f) Such Investor acknowledges and agrees that, before the issuance of any
Purchased Securities to him, her or it pursuant to this Agreement, he, she or,
as the case may be, it shall execute and deliver the Amended and Restated
Stockholder Agreement, pursuant to which the Purchased Securities to be issued
to such Investor pursuant to this Agreement shall be subject to the restrictions
set forth therein, including without limitation certain restrictions on the
voting and transfer of such securities.
<PAGE>
 
                                      -10-

     4.3. Governmental Consents. No consent, approval or authorization of, or
registration, qualification or filing with, any governmental agency or authority
is required for the execution and delivery by such Investor of this Agreement
and each of the Other Agreements to which such Investor is party, or for the
consummation by such Investor of the transactions contemplated hereby and
thereby.

     4.4. Repurchase Agreements. Each Investor who is, as of the date hereof,
party to a Repurchase Agreement hereby confirms that the Purchased Securities
acquired or to be acquired by such Investor pursuant to this Agreement
constitute and shall constitute "Shares" under and as defined in such Repurchase
Agreement for all purposes thereof.

     5. Register and Transfer of Shares.

     (a) Register of Shares. The Company shall keep at its principal office a
register in which shall be recorded the names and addresses of the record
holders of shares of Series A Common Stock, and all transfers of such shares.
References to the "holder" or "holder of record" of any shares of Series A
Common Stock shall mean the holder thereof unless the holder shall have
presented stock certificates evidencing such shares of Series A Common Stock to
the Company for transfer, and the transferee shall have been entered in said
register as a subsequent holder, in which case such terms shall mean such
subsequent holder. The ownership of any shares of the Series A Common Stock
shall be proven by such register and the Company may conclusively rely upon such
register.

     (b) Transfer of Shares. Upon surrender at such office of any certificate
representing shares of Series A Common Stock for registration of transfer, duly
endorsed, or accompanied by a written instrument of transfer duly executed by
the holder of such certificate or such holder's attorney duly authorized in
writing, then subject to compliance with the applicable provisions of this
Agreement, the Amended and Restated Stockholder Agreement, and applicable
securities laws, the Company shall issue, at its expense, one or more new
certificates, in such denomination or denominations as may be requested, for the
transferred shares of Series A Common Stock, and registered as the presenting
holder may have requested. The Company shall pay shipping and insurance charges,
from and to each holder's principal office, upon any transfer pursuant to this
section.

     (c) Replacement of Certificates. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction, or mutilation of
any certificate representing any shares of Series A Common Stock, and, in the
case of any such loss, theft, or destruction, upon delivery of an indemnity bond
in such reasonable amount as the Company may determine (or, in the case of any
such security held by Heritage or any other institutional holder, of an
unsecured indemnity agreement from such holder reasonably satisfactory to the
Company), or, in the case of any such mutilation, upon the surrender of such
certificate to the Company at its principal office for cancellation, the
Company, at its own expense, shall execute and deliver, in lieu thereof, a new
certificate of like tenor. Any lost, stolen, destroyed, or mutilated certificate
in lieu of which any
<PAGE>
 
                                     -11-

such new certificate has been so executed and delivered by the Company shall not
be deemed to be outstanding for any purpose.

     6. Confidential Information.

     Each of the Investors shall maintain the confidentiality of all
confidential, sensitive, or proprietary information of the Company and/or any of
its Subsidiaries and/or any of the other stockholders of the Company, including
without limitation with respect to their respective businesses, finances,
affairs and technology, which shall be and remain the exclusive property of the
Company or such Subsidiary or such stockholder, as the case may be, and unless
previously authorized in writing by the Company or such stockholder, and except
with respect to information that has otherwise become public through no action
or omission on the part of any such Investor, shall not disclose any such
information to any third party or use it for any purpose, other than in the
discharge of any such Investor's respective employment responsibilities (if any)
in the ordinary course of the Company's or any of its Subsidiaries' business.

     Notwithstanding the foregoing, if any of the Investors is required by law
or regulation to disclose any confidential, sensitive, or proprietary
information of the Company and/or any of its Subsidiaries and/or any of the
other stockholders of the Company, such Investor will provide the Company or
such stockholder, as the case may be, with prompt notice of such disclosure
obligation, so that the Company or such stockholder may seek a protective order
or take other appropriate action and/or waive compliance with this Section 6 to
the extent of such required disclosure. In the absence of such a waiver, if any
Investor is, in the opinion of his or its counsel, compelled to disclose any
such information upon pain of liability for contempt or other censure or
penalty, such Investor may disclose such information to the relevant court or
other tribunal or governmental authority without liability hereunder, but
notwithstanding such disclosure, such information shall remain confidential
under this Section 6 after such disclosure.

     7. General.

     7.1. Co-operation. Each of the parties hereto agrees to use his, her or its
commercially reasonable efforts to fulfill the conditions precedent to the
effectiveness of this Agreement. Each of the parties shall cooperate with the
others and use commercially reasonable efforts to prepare all necessary
documentation, to effect all necessary filings, and to obtain all necessary
permits, consents, approvals, and authorizations of all third parties and
governmental bodies necessary to consummate the transactions contemplated by
this Agreement. Each party shall have the right to review and approve in advance
all descriptions of or with respect to it that appear in any filing with any
governmental body made in connection with the transactions contemplated by this
Agreement. In exercising the foregoing right, the parties shall act reasonably
and as promptly as practicable.

     7.2. Survival of Representations and Warranties. The representations and
warranties of the parties hereto contained in this Agreement or otherwise made
in writing
<PAGE>
 
                                     -12-

in connection with the transactions contemplated hereby shall be deemed
material, and, notwithstanding any investigation by the Company or any of the
Investors, as the case may be, shall be deemed to have been relied on by them,
and shall survive the Closing and the consummation of the transactions
contemplated hereby.

     7.3. Expenses. Except as expressly provided otherwise in this Agreement,
each of the parties shall be responsible for and shall pay his, her or its own
expenses in connection with the negotiation and preparation of this Agreement
and the consummation of the transactions contemplated hereby.

     7.4. Benefits of Agreement; No Assignments; No Third-Party Beneficiaries.

     (a) This Agreement shall bind and inure to the benefit of the parties
hereto and their respective heirs, successors, and permitted assigns.

     (b) No party shall assign any rights or delegate any obligations hereunder
without the consent of the other parties, and any attempt to do so shall be
void.

     (c) Nothing in this Agreement is intended to or shall confer any rights or
remedies on any Person other than the parties hereto and their respective heirs,
successors, and permitted assigns.

     7.5. Notices. All notices, requests, payments, instructions, or other
documents to be given hereunder shall be in writing or by written
telecommunication, and shall be deemed to have been duly given if (i) delivered
personally (effective upon delivery), (ii) mailed by registered or certified
mail, return receipt requested, postage prepaid (effective five business days
after dispatch), (iii) sent by a reputable, established courier service that
guarantees next business day delivery (effective the next business day), or (iv)
sent by telecopier followed within 24 hours by confirmation by one of the
foregoing methods (effective upon receipt of the telecopy in complete, readable
form), addressed as follows (or to such other address as the recipient party may
have previously furnished to the sending party in accordance with this section):

     (a) If to the Company, to or in care of:

         IMPAC Group, Inc.
         1950 North Ruby Street
         Melrose Park, Illinois  60160-1178
         Attention:  Richard Block and David Underwood
         Telecopier No.  (708) 344-9113

         and in each case with copies to the other addresses specified in
         paragraphs (b) - (e) below.

 
<PAGE>
 
                                     -13-

     (b) If to either of the Heritage Funds, to or in care of:

          Heritage Partners Management Company, Inc.
          30 Rowes Wharf, Suite 300
          Boston, MA 02110
          Attention: Michael F. Gilligan, Managing Director
          Telecopier No. (617) 439-0689

          with a copy sent at the same time and by the same means to:

          David L. Engel, Esq.
          Bingham Dana LLP
          150 Federal Street
          Boston, Massachusetts 02110
          Telecopier No. (617) 951-8736

     (c) If to any Investor identified on the signature pages hereto as a
Klearfold Investor, to or in care of:

          Klearfold, Inc.
          364 Valley Road
          Warrington, Pennsylvania  18976
          Attention: H. Scott Herrin
          Telecopier No. (215) 343-0491

          with a copy sent at the same time and by the same means to:

          Richard Braemer, Esq.
          Ballard Spahr Andrews & Ingersoll
          1735 Market Street, 51st Floor
          Philadelphia, PA 19103-7599
          Telecopier No.: (215) 864-8999

     (d) If to any Investor identified on the signature pages hereto as an AGI
Investor, to such Investor in care of:

          AGI Incorporated
          1950 North Ruby Street
          Melrose Park, Illinois 60160-1178
          Attention:  Richard Block and David Underwood
          Telecopier No. (708) 344-9113
<PAGE>
 
                                      -14-

          with copies sent at the same time and by the same means to:

          Linda Chaplik Harris, Esq.
          Sonnenschein Nath & Rosenthal
          Suite 8000 Sears Tower
          233 South Wacker Drive
          Chicago, Illinois  60606
          Telecopier No. (312) 876-7934

     7.6. Counterparts. This Agreement may be executed by the parties in
separate counterparts, each of which when so executed and delivered shall be an
original, but all of which together shall constitute one and the same
instrument. In pleading or proving this Agreement, it shall not be necessary to
produce or account for more than one such counterpart.

     7.7. Captions. The captions of sections or subsections of this Agreement
are for reference only and shall not affect the interpretation or construction
of this Agreement.

     7.8. Equitable Relief. Each of the parties hereby acknowledges that any
breach by it of its obligations under this Agreement would cause substantial and
irreparable damage to the other parties, and that money damages would be an
inadequate remedy therefor, and accordingly, acknowledges and agrees that each
of the other parties shall be entitled to an injunction, specific performance,
and/or other equitable relief to prevent the breach of such obligations (in
addition to all other rights and remedies to which such party may be entitled in
respect of any such breach).

     7.9. Construction. The language used in this Agreement is the language
chosen by the parties to express their mutual intent, and no rule of strict
construction shall be applied against any party.

     7.10. Waivers. No waiver of any breach or default hereunder shall be valid
unless in a writing signed by the waiving party. No failure or other delay by
any party exercising any right, power, or privilege hereunder shall be or
operate as a waiver thereof, nor shall any single or partial exercise thereof
preclude any other or further exercise thereof or the exercise of any other
right, power, or privilege.

     7.11. Further Assurances. From time to time on and after the Closing Date,
each party hereto shall promptly execute and deliver all such further
instruments and other documents, and shall promptly take all such further
actions, as any other party hereto may reasonably request in order more
effectively to effect or confirm the transactions hereby contemplated and to
carry out the purposes of this Agreement.

     7.12. Entire Agreement. This Agreement, together with the exhibits and
schedules hereto, the Other Agreements, and the other agreements, instruments,
certificates and documents referred to herein and/or therein as having been or
to be
<PAGE>
 
                                      -15-

executed and delivered in connection with the transactions contemplated hereby
and thereby, contains the entire understanding and agreement among the parties,
and supersedes any prior understandings or agreements among them, or between or
among any of them, with respect to the subject matter hereof.

     7.13. Governing Law. This Agreement shall to the maximum lawful extent be
governed by and interpreted and construed in accordance with the internal laws
of the State of Delaware, as applied to contracts under seal made, and entirely
to be performed, within Delaware, and without reference to principles of
conflicts or choice of law.

<PAGE>
 
               Signature page 1 of 2 for Stock Purchase Agreement

     IN WITNESS WHEREOF, each of the parties has executed and delivered this
Agreement to the others as an agreement under seal as of the date first above
written.


            IMPAC GROUP, INC.



            By /s/ Signature Unintelligible
              ------------------------------
              Name:
              Title:


            HERITAGE FUND I, L.P.

            By: HF Partners I, L.P.,
                its general partner


            By /s/ Signature Unintelligible
              ------------------------------
              Name:
              Title:


            HERITAGE FUND II, L.P.

            By: HF Partners II, L.L.C.,
                its general partner


            By /s/ Signature Unintelligible
              ------------------------------
              Name:
              Title:


            AGI INVESTORS:

            /s/ Signature Unintelligible
            --------------------------------
            Richard Block
<PAGE>
 
              Signature page 2 of 2 for Stock Purchase Agreement
                                        
                    Signature Unintelligible
                    --------------------------------
                    David Underwood

                    Signature Unintelligible
                    --------------------------------
                    Donald W. Kosterka, as Trustee of
                    the Donald Kosterka Trust dated 5/17/92


                    
                    KLEARFOLD INVESTORS

                    Signature Unintelligible
                    --------------------------------
                    John McInerney
<PAGE>
 
                                  Schedule 1
                                  -------- -

                                   Investors
                                   ---------
                                        
<TABLE>
<CAPTION>
Investors                                   Number of Shares           Total Purchase Price                Jurisdiction
---------                           ------------------------           --------------------                ------------
                                    of Series A Common Stock
                                    ------------------------
 
<S>                                             <C>                          <C>                       <C>
Heritage Fund I, L.P.                              18,074.27                    $11,000,000               Massachusetts
 
Heritage Fund II, L.P.                             72,297.08                    $44,000,000               Massachusetts
 
Richard Block                                       4,929.35                    $ 3,000,000                 Connecticut
 
Donald W. Kosterka, as Trustee                        492.94                    $   300,000
 of the Donald Kosterka Trust
 dated 5/17/92
 
David Underwood                                       246.47                    $   150,000                    Illinois
 
John McInerney                                        205.39                    $   125,000                Pennsylvania
 
</TABLE>