Exhibit 5.1

Paul, Weiss, Rifkind, Wharton & Garrison LLP

1285 Avenue of the Americas

New York, New York 10019-6064

212-373-3000

212-757-3990

April 13, 2012

Hexion U.S. Finance Corp.

180 East Broad Street

Columbus, Ohio 43215

Hexion Nova Scotia Finance, ULC

180 East Broad Street

Columbus, Ohio 43215

Registration Statement on Form S-1

(Registration No. 333-176961)

Ladies and Gentlemen:

In connection with the Registration Statement on Form S-1 (the “Registration Statement”) of Hexion U.S. Finance Corp., a Delaware corporation (“Hexion U.S.”), Hexion Nova Scotia Finance, ULC, an unlimited liability company organized under the laws of Nova Scotia (“Hexion Nova Scotia” and, together with Hexion U.S., the “Issuers”), the persons listed on Schedule I hereto (each, a “Delaware Corporate Guarantor”), the persons listed on Schedule II hereto (each, a “Delaware LLC

1

Guarantor” and, together with the Delaware Corporate Guarantors, the “Delaware Guarantors”) and the person listed on Schedule III hereto (the “New Jersey Corporate Parent Guarantor” and, together with the Delaware Guarantors, the “Guarantors”) filed with the Securities and Exchange Commission pursuant to the Securities Act of 1933, as amended (the “Act”), and the rules and regulations thereunder (the “Rules”), you have asked us to furnish our opinion as to the legality of the securities being registered under the Registration Statement. The Registration Statement relates to the registration under the Act of $134,016,000 aggregate principal amount of the Issuers’ 9.00% Second-Priority Senior Secured Notes due 2020 (the “Notes”) and the guarantees of the Notes by the Guarantors (the “Note Guarantees” and, collectively with the Notes, the “Securities”) that may be offered from time to time by Euro VI (BC) S.à r.l., a noteholder of the Issuers. The Notes and the Note Guarantees were issued pursuant to an indenture, dated as of November 5, 2010 (the “Indenture”), among Hexion U.S., Hexion Nova Scotia, the Guarantors and Wilmington Trust Company, as trustee.

In connection with the furnishing of this opinion, we have examined originals, or copies certified or otherwise identified to our satisfaction, of the following documents (collectively, the “Documents”):

1. the Registration Statement;

2. the Indenture, including the form of the Notes attached thereto, included as Exhibit 4.8 to the Registration Statement; and

3. the Registration Rights Agreement, dated as of November 5, 2010 (the “Registration Rights Agreement”), between Hexion U.S., Hexion Nova Scotia, the Guarantors and Euro VI (BC) S.à r.l., included as Exhibit 4.9 to the Registration Statement.

2

In addition, we have examined (i) such corporate records of the Issuers and the Guarantors as we have considered appropriate, including, as applicable, a copy of the certificate of formation or incorporation, as amended, and the limited liability company operating agreement or by-laws, as amended, of Hexion U.S. and each Delaware Guarantor, certified by Hexion U.S. and each Delaware Guarantor as in effect on the date of this letter, and copies of resolutions of the board of managers, the sole member or the board of directors, as applicable, of Hexion U.S. and each Delaware Guarantor relating to the issuance of the Securities, certified by Hexion U.S. and each Delaware Guarantor and (ii) such other certificates, agreements and documents as we deemed relevant and necessary as a basis for the opinions expressed below. We have also relied upon the factual matters contained in the representations and warranties of the Issuers and the Guarantors made in the Documents and upon certificates of public officials and the officers of the Issuers and the Guarantors.

In our examination of the documents referred to above, we have assumed, without independent investigation, the genuineness of all signatures, the legal capacity of all individuals who have executed any of the documents reviewed by us, the authenticity of all documents submitted to us as originals, the conformity to the originals of all documents submitted to us as certified, photostatic, reproduced or conformed copies of valid existing agreements or other documents, the authenticity of all the latter documents and that the statements regarding matters of fact in the certificates, records, agreements, instruments and documents that we have examined are accurate and complete. We have also assumed that the Securities, when issued, were duly executed, delivered and authenticated in accordance with the terms of the Indenture. With regard to certain matters of state and Canadian provincial law, we have relied, with the Issuers’

3

permission, upon the opinions of Connell Foley LLP and Stewart McKelvey, filed as Exhibits 5.2 and 5.3, respectively, to the Registration Statement.

Based upon the above, and subject to the stated assumptions, exceptions and qualifications, we are of the opinion that:

1. The Notes constitute valid and legally binding obligations of the Issuers, enforceable against the Issuers in accordance with their terms, except that the enforceability of the Notes may be subject to bankruptcy, insolvency, reorganization, fraudulent conveyance or transfer, moratorium or similar laws affecting creditors’ rights generally and subject to general principles of equity (regardless of whether enforceability is considered in a proceeding in equity or at law).

2. The Note Guarantee of each Guarantor is a valid and legally binding obligation of such Guarantor, enforceable against such Guarantor in accordance with its terms, except that the enforceability of the Note Guarantees may be subject to bankruptcy, insolvency, reorganization, fraudulent conveyance or transfer, moratorium or similar laws affecting creditors’ rights generally and subject to general principles of equity (regardless of whether enforceability is considered in a proceeding in equity or at law).

The opinions expressed above are limited to the laws of the State of New York, the General Corporation Law of the State of Delaware and the Limited Liability Company Act of the State of Delaware. Our opinion is rendered only with respect to the laws, and the rules, regulations and orders under those laws, that are currently in effect.

We hereby consent to use of this opinion as an exhibit to the Registration Statement and to the use of our name under the heading “Legal Matters” contained in the prospectus included in the Registration Statement. In giving this consent, we do not

4

thereby admit that we come within the category of persons whose consent is required by the Act or the Rules.

Very truly yours,

/s/ Paul, Weiss, Rifkind, Wharton & Garrison LLP

PAUL, WEISS, RIFKIND, WHARTON &

GARRISON LLP

5

SCHEDULE I

DELAWARE CORPORATE GUARANTORS

Name	State of Incorporation / Organization
Momentive Specialty Chemicals Investments Inc.	Delaware
HSC Capital Corporation	Delaware
Lawter International Inc.	Delaware
Momentive International Inc.	Delaware
Oilfield Technology Group, Inc.	Delaware

SCHEDULE II

DELAWARE LLC GUARANTORS

Name	State of Incorporation / Organization
Borden Chemical Foundry, LLC	Delaware
Momentive CI Holding Company (China) LLC	Delaware
NL Coop Holdings LLC	Delaware

SCHEDULE III

NEW JERSEY CORPORATE PARENT GUARANTOR

Name	State of Incorporation / Organization
Momentive Specialty Chemicals Inc.	New Jersey