EX-10.28





 Exhibit 10.28 

PATENT SECURITY AGREEMENT, dated as of July 31, 2020 (this “Agreement”), among STERIGENICS U.S., LLC (the
“Grantor”) and WILMINGTON TRUST, NATIONAL ASSOCIATION, in its capacity as First Lien Notes Collateral Agent under the Indenture (as defined below) (in such capacity, together with its successors and assigns, the “First Lien
Notes Collateral Agent”). 
 Reference is made to (a) the Indenture dated as of July 31, 2020 (as amended, restated,
supplemented or otherwise modified from time to time, the “Indenture”) among SOTERA HEALTH TOPCO, INC., a Delaware corporation (“Holdings”), SOTERA HEALTH HOLDINGS, LLC, a Delaware limited liability company (the
“Issuer”), WILMINGTON TRUST, NATIONAL ASSOCIATION, as Trustee and the First Lien Notes Collateral Agent and (b) the First Lien Collateral Agreement dated of July 31, 2020 (as amended, restated, supplemented or otherwise modified from
time to time, the “First Lien Collateral Agreement”) among the Issuer, the other Grantors from time to time party thereto, Holdings, and the First Lien Notes Collateral Agent. Accordingly, the parties hereto agree as follows: 

SECTION 1. Terms. Capitalized terms used in this Agreement and not otherwise defined herein have the meanings specified in the First
Lien Collateral Agreement. The rules of construction specified in Section 1.01(b) of the First Lien Collateral Agreement also apply to this Agreement. 

SECTION 2. Grant of Security Interest. As security for the payment or performance, as the case may be, in full of the Notes
Obligations, the Grantor hereby grants to the First Lien Notes Collateral Agent, its successors and assigns, for the benefit of the Secured Parties, a security interest (the “Security Interest”) in all of such Grantor’s right, title
and interest in, to and under the United States Patents listed on Schedule I attached hereto (the “Patent Collateral”). This Agreement is not to be construed as an assignment of any patent or patent application. 

SECTION 3. First Lien Collateral Agreement. The Grantor hereby acknowledges and affirms that the rights and remedies of the First Lien
Notes Collateral Agent with respect to the Patent Collateral are more fully set forth in the First Lien Collateral Agreement, the terms and provisions of which are hereby incorporated herein by reference as if fully set forth herein. In the event of
any conflict between the terms of this Agreement and the First Lien Collateral Agreement, the terms of the First Lien Collateral Agreement shall govern. 

SECTION 4. Termination. Subject to Section 5.13 of the First Lien Collateral Agreement, upon the occurrence of a Termination Event
(other than those provisions in the Indenture expressly contemplated to survive a Termination Event and any contingent obligations not yet due and owing under Sections 7.07 and 8.06 of the Indenture and Article 2 of the Indenture), the security
interest granted herein shall terminate and the First Lien Notes Collateral Agent shall, without recourse, representation or warranty of any kind, execute, acknowledge, and deliver to the Grantors all instruments in writing prepared by or on behalf
of the Grantor in recordable form to evidence and release the collateral pledge, grant, assignment, lien and security interest in the Patent Collateral under this Agreement. 












 SECTION 5. Counterparts. This Agreement may be executed in counterparts (and by
different parties hereto on different counterparts), each of which shall constitute an original but all of which when taken together shall constitute a single contract. Delivery of an executed signature page to this Agreement by facsimile or other
electronic transmission shall be effective as delivery of a manually signed counterpart of this Agreement. 
 SECTION 6. Governing
Law. This Agreement shall be construed in accordance with and governed by the laws of the State of New York. 
 SECTION 7. Concerning
the First Lien Notes Collateral Agent. The First Lien Notes Collateral Agent makes no representations as to the validity or sufficiency of this Agreement. Wilmington Trust, National Association is executing this Agreement not in its individual
or corporate capacity, but solely in its capacity as First Lien Notes Collateral Agent under the Indenture. In acting hereunder, the First Lien Notes Collateral Agent shall be entitled to all of the rights, privileges, immunities and indemnities
granted to it under the Indenture, including without limitation those set forth in Articles 7 and 12 of the Indenture, as if such rights, privileges, immunities and indemnities were set forth herein. 

[Remainder of Page Intentionally Left Blank] 

  
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 IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement as of the day and
year first above written. 
  

			
	STERIGENICS U.S., LLC, as Grantor
		
	By	 	/s/ Scott J. Leffler 
		 	Name: Scott J. Leffler
		 	Title:   Chief Financial Officer & Treasurer


 [Signature Page Patent Security Agreement] 












 
			
	WILMINGTON TRUST, NATIONAL ASSOCIATION, as First Lien Notes Collateral Agent
		
	By:	 	/s/ W. Thomas Morris II
		 	Name: W. Thomas Morris II
		 	Title:   Vice President


 [Signature Page Patent Security Agreement]