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 [Search a list of Patent Appplications for class 528]   CLASS 528,SYNTHETIC RESINS OR NATURAL RUBBERS -- PART OF THE CLASS 520 SERIES
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SECTION I - CLASS DEFINITION

Class 528 provides for all processes of preparing polymers from reactants wherein at least one reactant is devoid of ethylenic unsaturation. In addition, Class 528 provides for processes of removing contaminates or undesirable materials from a polymer, for processes of physically treating polymer-material, or for processes of chemically modifying a polymer without the addition of any extraneous material.

SECTION II - LINES WITH OTHER CLASSES AND WITHIN THIS CLASS

Listed below are rules to be followed in (1) placing patents into Class 528 and in (2) determining the appropriate subclasses to be searched in Class 528.

A. Classification in Class 528, subclasses 1-425 is on the basis of the reactants utilized. Some general rules to be followed in determining such reactants are as follows:

Process claim recites preparing an intermediate which is then reacted in a further step in preparing an additional intermediate

A + BC (Intermediate)

C (Intermediate) + D solid final product.

In this case, the reactants are A, B, and D. If reactant D is first appearing in the schedule array, there is no necessary cross-referencing to A, B, or to the intermediate C; however, if A or B is first appearing then a cross-reference should be placed in the subclass providing for C.

B. Process claim starts with intermediate C (i.e., no positive preparation step claimed for intermediate C). Reaction calls for C (Intermediate) + D solid final product. In this case, reactants are C and D and classification is on the basis of the first reactant appearing in the schedule array. See (M) for classification of an intermediate condensation product.

C. Patentee claims polymer C. Examiner or searcher must look to the disclosure to see reactants utilized.

D. A liquid polymer which is exposed to an after treatment step is classified as a reactant.

E. When the claims and disclosures are silent as to whether the polymer treated is a liquid or solid, the polymeric material is to be regarded as a liquid and therefore as a reactant.

F. When the claims are silent as to whether the polymer prepared is a solid or liquid and the disclosure is alternative, disclosing both solid and liquid materials, original classification is on the basis of general rules of schedule hierarchy and the alternative species is mandatorily cross-referenced.

G. When the claims are drawn to alternative claimed subject matter involving solid and liquid polymers, original classification is appropriate on the basis of general rules of schedule hierarchy and the alternative species is mandatorily cross-referenced.

H. Where there are generic claims presented (i.e., alternative)as well as species claims such species claims will generally control for classification purposes over the generic presented claims.

I. Markush claims of A or B are regarded as individual species and classification is appropriate on the basis of general rules of schedule hierarchy.

J. Claims which are drawn to an intermediate condensation product as a reactant wherein applicant alleges indefinite structure for the condensation product, are classified on the basis of the reactants utilized in preparing the intermediate condensation product.

Urea-formaldehyde, phenol-formaldehyde, and methylol melamine are considered as being indefinite materials and are classified as urea + formaldehyde, phenol + formaldehyde, and melamine + formaldehyde.

The reaction of a urea-formaldehyde condensation material + melamine product to yield product is C is classified on the basis of either urea, formaldehyde, or melamine, depending upon which is the first-appearing reactant provided in the schedule array.

If, however, the intermediate condensation product is of such definiteness as to be definable by applicant as a chemical compound, e.g., ester, polyester, polyether, polyamide, etc., such intermediate will be viewed as a compound and classified accordingly. An example of the aforementioned concept is as follows: Applicant starts with a (C) polyester prepared by reacting A + B. (C)polyester + isocyanate (D)--- polymer (E). Reactants are C and D and claim is cross-referenced to A and B if desired. If applicant identifies the final reactant product only in terms of the reactants necessary to produce such reactant product (e.g., urea-formaldehyde, etc.) classification is to be made on the basis of the reactants recited.

K. In all cases where doubt exists as to whether a material that is present during a reaction is a reactant or a nonreactant (i.e., specified material) such doubt has been resolved by looking at the material as if it were a reactant.

L. Applicants" statements as to functions of materials (e.g., catalyst, reactant, solvent, etc.) are to be taken literally and to be followed. An exception to the preceding rule is in those subclasses where specified rules are enumerated. If the Examiner has any doubts as to statements of functions, such doubts can be resolved by adequate cross- referencing. A specific exception to the rule enumerated above regarding applicants" statements is the question as to whether a material is a solid resin for the particular chemical modification subclasses which are provided in the schedule. In those cases where the claims are silent, the Examiner may resolve the question by looking at the total disclosure of the patent.

M. Classification into subclasses 1-425 is primarily on the basis of reactant utilized. It is possible, however, that polymeric products which may be identical in structure may be prepared from different reactants, and that these reactant may not be claimed or disclosed in the patent being classified. In those instances where a product is claimed which the Examiner believes may be formed from reactants which are not disclosed in the patent at hand, an optional cross-reference into the nonclaimed or disclosed reactant area may be highly desirable and appropriate.

The following rules apply in classifying a claim into Class 528 in those subclasses of the schedule which provide for processes (i.e., in specified material areas).

A. Patents that claim a product and process, wherein both the product and the process are specifically provided for in the schedule, are classified in the process area and cross-referenced to the product area.

B. Patents that claim both a provided for product and a process of polymerizing, and wherein the product is claimed in process terms, are classified on the basis of the process and cross-referenced to the first-appearing reactant in the schedule utilized in preparing the polymer.

C. Patents that claim a product solely in process terms are classified on the basis of the process, when said process is provided in the schedule and cross-referenced to the first-appearing reactant in the schedule utilized in preparing the polymer.

D. Patents that claim a product in process terms, and wherein the process is not provided, are classified on the basis of the first-appearing reactant in the schedule utilized in preparing the polymer.

E. Patents that claim a polymerizable composition or the preparation of a polymerizable composition are classified on the basis of the first-appearing reactant in the schedule that is part of the polymerizable composition.

F. Patents that claim a polymer only are classified on the basis of the first-appearing reactant in the schedule that has been used in preparing the polymer.

G. Patents that claim merely vulcanizing, curing, or cross-linking or a polymer proper for this area, without the presence of a specified vulcanizing, curing, or cross-linking agent, or the amount of the chemical agent or the vulcanized, cured, or cross-linked product of such a reaction are classified on the basis of the first-appearing reactant in the schedule that has been polymerized in the preparing the polymer.

H. Patents that claim a polymer which is the result of a degradation of a polymer proper for this area, and wherein the degradation has been effected in the absence of any chemical agent, are classified on the basis of the initial first-appearing reactant in the schedule that has been polymerized in preparing the previously formed polymer that is degraded.

I. This class provides for a composition of a polymer proper for this class admixed with a broadly claimed nonreactant not identifiable by a chemical atom or amount; or for a process of preparing a composition wherein the nonreactant material is not identified by a chemical atom or amount and wherein the process of forming the composition recites no process condition other than mere polymerizing. (See Class 523, section I of the Class Definition, for a discussion of nonreactant materials and designated nonreactant materials.)

SECTION III - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

525Synthetic Resins or Natural Rubbers,   subclasses 242+ for products resulting from, or involving a polymer proper for this class reacted with an ethylenically unsaturated reactant.

SECTION IV - GLOSSARY

REACTANT

A reactant for purposes of this Class is a material which occurs in a polymer as a repeating unit and is present in at least three units. As used herein, reactant is meant to exclude catalyst residues, chain transfer agents, etc.

WITH

For purposes of this class, the term "with" under a specific reactant subclass requires the presence of the specific reactant with a different reactant which meets the parameters set forth by the "with" definition.

CONTAINS

For purposes of this class, the term "contains" under a specific reactant subclass includes the term "with" and merely requires the presence of the "contains" material. The required moiety, element, etc., may be in the specific reactant or in an additional reactant.

SUBCLASSES

[List of Patents for class 528 subclass 1]    1FROM PLANT MATERIAL OF UNKNOWN CONSTITUTION
 This subclass is indented under subclass 1.  Subject matter under Class 520, ... involving polymers derived from a plant-containing material of unknown constitution or processes of polymerizing; polymerizable compositions containing a plant material of unknown composition or processes of preparing.
(1) Note. The types of plant materials which are proper for this subclass are those whose composition and constitution are not sufficiently determined to enable their classification in the later subclasses on the basis of a particular reactant(s).
(2) Note. Types of materials included herein are nut shell liquors and essential oils. This subclass includes cashew nut shell liquor containing unseparated anacardic acid or Cardanol.
(3) Note. This subclass includes derivatives of plant materials which are undefinable as to chemical identity.
(4) Note. Materials which are substantially known as to chemical composition are excluded from this subclass or indents hereunder and are classified below in the schedule on the basis of the first specific reactant which is part of the chemical composition. If in any claim, any doubt exists as to whether a composition is of sufficient chemical identity so as to be classified as a specific reactant, then such doubt is to be resolved by classifying the claim as an original in this area and cross-referenced to the appropriate reactant subclass.
(5) Note. A chemical agent for purposes of this subclass is material which is added to solid polymer and causes or is present during a process wherein a chemical change of the solid polymer is effected.

SEE OR SEARCH THIS CLASS, SUBCLASS:

86+,for Cardanol, anacardic acid or derivative, tannins, or tannic acid, cresylic acid, or coal tar extracts as reactants.
  
[List of Patents for class 528 subclass 2]    2From cashew material with a sulfur-containing reactant
 This subclass is indented under subclass 1.  Subject matter wherein material derived from a cashew plant and a sulfur-containing material are reactants.
  
[List of Patents for class 528 subclass 3]    3From cashew material with an aldehyde or derivative
 This subclass is indented under subclass 1.  Subject matter wherein material derived from a cashew plant and an aldehyde or derivative are reactants.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for the definition of the terms "aldehyde".
  
[List of Patents for class 528 subclass 4]    4FROM BORON REACTANT HAVING AT LEAST ONE BORON TO HYDROGEN OR BORON TO CARBON BOND
 This subclass is indented under subclass 1.  Subject matter under Class 520, ... involving polymer products derived from a boron-containing reactant wherein at least one atom of boron is bonded directly to a hydrogen or carbon atom or processes of polymerizing; polymerizable compositions containing as a reactant a compound of boron wherein boron is directly bonded to an atom of hydrogen or carbon or processes of preparing.

SEE OR SEARCH THIS CLASS, SUBCLASS:

480+,for processes of preparing a polymer not involving a chemical modification of the polymer, by the addition of a material thereto, and for chemically modifying material other than the polymer. Subclasses 480+ also provide for processes of admixing with a broadly claimed nonreactant material.

SEE OR SEARCH CLASS:

526Synthetic Resins or Natural Rubber,   subclass 239 for a polymer derived from a boron-containing ethylenic reactant as sole monomer, or for a boron-containing interpolymer wherein all of the reactants used in preparing the polymer are ethylenically unsaturated.
  
[List of Patents for class 528 subclass 5]    5Boron reactant contains a silicon atom
 This subclass is indented under subclass 4.  Subject matter wherein the boron-containing reactant having a or bond also contains a silicon atom.
  
[List of Patents for class 528 subclass 6]    6Boron reactant contains a phosphorus atom
 This subclass is indented under subclass 4.  Subject matter wherein the boron-containing reactant having a or bond also contains a phosphorus atom.
  
[List of Patents for class 528 subclass 7]    7Boron reactant contains a nitrogen atom
 This subclass is indented under subclass 4.  Subject matter wherein the boron-containing reactant having a or bond also contains a nitrogen atom.
  
[List of Patents for class 528 subclass 8]    8Boron reactant contains a boron atom bonded to at least one atom of oxygen
 This subclass is indented under subclass 4.  Subject matter wherein the boron-containing reactant having a or bond also contains at least one atom of oxygen directly bonded to the boron atom of the or containing moiety.
  
[List of Patents for class 528 subclass 9]    9FROM HEAVY METAL OR ALUMINUM REACTANT HAVING AT LEAST ONE HYDROGEN-TO-HEAVY METAL OR -ALUMINUM BOND OR AT LEAST ONE CARBON-TO-HEAVY METAL OR -ALUMINUM BOND
 This subclass is indented under subclass 1.  Subject matter under Class 520, ... , involving polymer products derived from a heavy metal or aluminum-containing reactant wherein at least one atom of a heavy metal or aluminum is bonded directly to an atom of hydrogen or carbon or processes of polymerizing; polymerizable compositions containing as a reactant a compound of a heavy metal or aluminum wherein the heavy metal or aluminum atom is directly bonded to a hydrogen or carbon atom or processes of preparing.
(1) Note. Heavy metal denotes a metal atom having a specific gravity greater than four.

SEE OR SEARCH THIS CLASS, SUBCLASS:

395,for a polymer derived from a heavy metal-or aluminum-containing reactant.
480+,for processes of preparing a polymer not involving a chemical modification of the polymer, by the addition of a material thereto, and for chemically modifying material other than the polymer. Subclasses 480+ also provide for processes of admixing with a broadly claimed nonreactant material.

SEE OR SEARCH CLASS:

526Synthetic Resins or Natural Rubbers,   subclasses 240+ for a polymer derived from a metal-containing ethylenic reactant as sole monomer or for a metal-containing interpolymer wherein all of the reactants used in preparing the polymer are ethylenically unsaturated.
  
[List of Patents for class 528 subclass 10]    10FROM SILICON REACTANT HAVING AT LEAST ONE SILICON-TO-HYDROGEN OR -CARBON BOND
 This subclass is indented under subclass 1.  Subject matter under Class 520, ... , involving polymer products derived from a silicon-containing reactant wherein at least one atom of silicon is bonded directly to an atom of hydrogen or carbon or processes of polymerizing; polymerizable compositions containing as a reactant a compound of silicon wherein a silicon atom is directly bonded to a hydrogen or carbon atom or processes of preparing.

SEE OR SEARCH THIS CLASS, SUBCLASS:

480+,for processes of preparing a polymer not involving a chemical modification of the polymer, by the addition of a material thereto, and for chemically modifying material other than the polymer. Subclasses 480+ also provide for processes of admixing with a broadly claimed nonreactant material.

SEE OR SEARCH CLASS:

526Synthetic Resins or Natural Rubber,   subclass 279 for a polymer derived from a silicon-containing ethylenic reactant as sole monomer or for a silicon-containing inter-polymer wherein all of the reactants used in preparing the polymer are ethylenically unsaturated.
  
[List of Patents for class 528 subclass 12]    12Polymerizing in the pressence of a specified material other than a reactant
 This subclass is indented under subclass 10.  Subject matter wherein a R3SiH or R3Si-CR3 reactant is polymerized in the presence of a specified material.
(1) Note. Silicones or polysiloxanes defined by the formula RnSiO wherein R is C or H are considered to be polymers and are proper for this area.

SEE OR SEARCH THIS CLASS, SUBCLASS:

33+,for organopolysiloxane used as reactants.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "specified material".
  
[List of Patents for class 528 subclass 13]    13Material is a boron-containing material
 This subclass is indented under subclass 12.  Subject matter wherein the specified material is elemental boron or a boron-containing compound.
  
[List of Patents for class 528 subclass 14]    14Material is a metal-containing material
 This subclass is indented under subclass 12.  Subject matter wherein the specified material is an elemental metal or metal-containing compound.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "metals".
  
[List of Patents for class 528 subclass 15]    15Material contains a Group VIII metal atom
 This subclass is indented under subclass 14.  Subject matter wherein the metal atom is a Group VIII metal atom (i.e., Fe, Co, Ni, Ru, Pd, Os, Ir, Pt, Rh).
  
[List of Patents for class 528 subclass 16]    16Material contains a Group IIIA metal
 This subclass is indented under subclass 14.  Subject matter wherein the specified material contains a Group IIIA metal atom in elemental or compound form, i.e., Al, Ga, In, Ti.
  
[List of Patents for class 528 subclass 17]    17Material contains a Group IVB metal atom
 This subclass is indented under subclass 14.  Subject matter wherein the specified material contains a Group IVB metal atom in elemental or compound form, i.e., Ti, Zr, Hf.
  
[List of Patents for class 528 subclass 18]    18Material contains a Group IVA metal atom
 This subclass is indented under subclass 14.  Subject matter wherein the specified material contains a Group IVA metal atom in elemental or compound form, i.e., Ge, Sn, Pb.
  
[List of Patents for class 528 subclass 19]    19Material contains a heavy metal atom
 This subclass is indented under subclass 14.  Subject matter wherein the specified material contains a heavy metal atom in elemental or compound form.
(1) Note. Heavy metal denotes a metal atom having a specific gravity greater than four.
  
[List of Patents for class 528 subclass 20]    20Material contains an alcohol, alcoholate, or ether compound
 This subclass is indented under subclass 12.  Subject matter wherein the specified material contains an ether, alcohol, or salt thereof.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the terms "ether" and "alcohol".
  
[List of Patents for class 528 subclass 21]    21Material is a nitrogen-containing compound
 This subclass is indented under subclass 12.  Subject matter wherein the specified material is a nitrogen-containing compound.
  
[List of Patents for class 528 subclass 22]    22Nitrogen-containign silicon compound
 This subclass is indented under subclass 21.  Subject matter wherein silicon and nitrogen are part of the same compound.
  
[List of Patents for class 528 subclass 23]    23Material contains a phosphorus or sulfur atom
 This subclass is indented under subclass 12.  Subject matter wherein the specified material contains at least one atom of phosphorus or sulfur.
  
[List of Patents for class 528 subclass 24]    24Material contains a compound having an O-O group, e.g., peroxide, etc.
 This subclass is indented under subclass 12.  Subject matter wherein the specified material contains a compound having at least one -O-O (peroxy) group.
  
[List of Patents for class 528 subclass 25]    25With organic silicon-free reactant
 This subclass is indented under subclass 10.  Subject matter wherein a polymer has been derived from at least one or containing material and at least one reactant which is an organic compound and which organic compound is devoid of any silicon atom.
(1) Note. This subclass, for example, would include the reaction between two or containing reactants and at least one organic silicon-free reactant.
  
[List of Patents for class 528 subclass 26]    26Organic Si-free reactant is a carboxylic acid or derivative
 This subclass is indented under subclass 25.  Subject matter wherein at least one silicon-free organic reactant contains a carboxylic acid group or is a derivative thereof.

SEE OR SEARCH THIS CLASS, SUBCLASS:

520,Synthetic Resins or Natural Rubbers, see the Glossary for a definition of the term "carboxylic acid or derivative".

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "carboxylic acid or derivative".
  
[List of Patents for class 528 subclass 26.5]    26.5Reactant which is a fatty acid glycerol ester, a fatty acid or salt derived from a naturally occurring glyceride, tall oil, or a fatty acid derived from tall oil:
 This subclass is indented under subclass 26.  Subject matter wherein said silicon-free reactant is a fatty acid glycerol ester, a fatty acid or salt derived from a naturally occurring glyceride, tall oil, or a fatty acid derived from tall oil.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the definition of "fatty acid" in the Glossary for discussion of terms used herein.
  
[List of Patents for class 528 subclass 27]    27Organic Si-free reactant contains a heterocyclic ring
 This subclass is indented under subclass 25.  Subject matter wherein at least one silicon-free organic reactant contains a heterocyclic ring.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "heterocyclic".
  
[List of Patents for class 528 subclass 28]    28Organic Si-free reactant is a nitrogen-containing compound
 This subclass is indented under subclass 25.  Subject matter wherein at least one silicon-free organic reactant is a nitrogen-containing compound.
  
[List of Patents for class 528 subclass 29]    29Organic Si-free reactant is an alcohol or alcoholate
 This subclass is indented under subclass 25.  Subject matter wherein at least one silicon-free organic reactant is an alcohol or alcoholate thereof.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "alcohol".
  
[List of Patents for class 528 subclass 30]    30From silicon-containing reactant having at least one polyvalent atom other than carbon, oxygen, or nitrogen
 This subclass is indented under subclass 10.  Subject matter wherein at least one or containing reactant having a polyvalent atom which is other than carbon, oxygen, or nitrogen (e.g., sulfur, phosphorus, etc.).
  
[List of Patents for class 528 subclass 31]    31Silicon reactant contains a silicon-to-hydrogen bond
 This subclass is indented under subclass 10.  Subject matter wherein the silicon-containing reactant possesses at least one bond.
  
[List of Patents for class 528 subclass 32]    32Silicon reactant contains an ethylenically unsaturated group
 This subclass is indented under subclass 10.  Subject matter wherein the containing reactant possesses at least one ethylenically unsaturated group.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "ethylenically unsaturated".
526Synthetic Resins or Natural Rubbers,   subclass 279 for a polymer derived from an ethylenically unsaturated silicon-containing reactant as sole monomer or for a silicon-containing interpolymer wherein all of the reactants used in preparing the polymer are ethylenically unsaturated.
  
[List of Patents for class 528 subclass 33]    33Silicon reactant contains two or more silicon atoms
 This subclass is indented under subclass 10.  Subject matter wherein a containing reactant possesses at least two silicon atoms.
  
[List of Patents for class 528 subclass 34]    34With silicon reactant containing a single silicon atom
 This subclass is indented under subclass 33.  Subject matter wherein a containing compound possessing at least two silicon atoms is reacted with a silicon compound containing a single silicon atom.
  
[List of Patents for class 528 subclass 35]    35Silicon reactamt contains only carbon atom, only a carbon chain, or chain of carbon and oxygen atoms only between two silicon atoms
 This subclass is indented under subclass 33.  Subject matter wherein at least two silicon atoms of a containing compound are joined by a single carbon atom, by a carbon chain, or by a chain composed only of carbon and oxygen atoms.
  
[List of Patents for class 528 subclass 36]    36Silicon reactant contains at least one halogen atom bonded to a carbon atom which carbon atom is not an acyl halide carbon atom
 This subclass is indented under subclass 33.  Subject matter wherein a containing compound with at least two silicon atoms contains a carbon-to-halogen bond and which carbon atom is not double bonded to an oxygen atom.
  
[List of Patents for class 528 subclass 37]    37Reactant contains a silicon atom as a ring member of a cyclic compound
 This subclass is indented under subclass 33.  Subject matter wherein a containing compound possesses at least two silicon atoms with at least one silicon atom as ring member of a nonhetero-cyclic ring (e.g., cyclic trisiloxane, etc.).

SEE OR SEARCH THIS CLASS, SUBCLASS:

35,for a cyclic silicon reactant wherein two or more silicon atoms in the ring are joined by carbon atoms.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "heterocyclic".
  
[List of Patents for class 528 subclass 38]    38Silicon reactant contains an amine nitrogen atom
 This subclass is indented under subclass 10.  Subject matter wherein the containing reactant possesses at least one amino-nitrogen atom.

SEE OR SEARCH THIS CLASS, SUBCLASS:

41,for a nitrogen-containing and -Si-C- containing reactant wherein the nitrogen atom exists solely therein either as a carboxylic acid amide or as a carboxylic acid nitrile, (-C=N).

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "amine".
  
[List of Patents for class 528 subclass 39]    39With silicon reactant which is free of any silicon to carbon bond
 This subclass is indented under subclass 10.  Subject matter wherein a containing material is reacted with at least one silicon compound which is devoid of any bond (e.g., SiCl4, Si(OR)4, etc.).

SEE OR SEARCH THIS CLASS, SUBCLASS:

31,for the interaction of a Si-H containing compound and a silicon compound which is devoid of any silicon-carbon bond.
  
[List of Patents for class 528 subclass 40]    40Silicon reactant contains a fused, bridged, or cycloaliphatic ring
 This subclass is indented under subclass 10.  Subject matter wherein a containing compound contains at least one fused or bridged ring system or contains at least one ring composed solely of carbon atoms which is nonaromatic.
(1) Note. A bridged or fused ring system for purposes of this subclass requires that a given ring system be attached at two different nuclear atoms of its system to an atom or chain of atoms which, taken together with the two nuclear atoms, forms an additional ring structure.
  
[List of Patents for class 528 subclass 41]    41Silicon containing carboxylic acid or derivative or from a silicon derivative of a nonsilicon containing carboxylic acid
 This subclass is indented under subclass 10.  Subject matter wherein the containing reactant contains at least one carboxylic acid group or is a derivative thereof.

SEE OR SEARCH THIS CLASS, SUBCLASS:

271,for an additional definition the "carboxylic acid".

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "carboxylic acid or derivative".
  
[List of Patents for class 528 subclass 42]    42Silicon reactant contains at least one halogen atom bonded to a carbon atom which carbon atom is not an acyl halide carbon atom
 This subclass is indented under subclass 10.  Subject matter wherein the containing compound possesses a carbon-to-halogen bond and which carbon atom bonded to the halogen atom is other than as a carbonyl carbon atom (e.g., halo).
  
[List of Patents for class 528 subclass 43]    43Silicon reactant contains an aryl group
 This subclass is indented under subclass 10.  Subject matter wherein the containing reactant possesses at least one aromatic group therein.
  
[List of Patents for class 528 subclass 44]    44FROM REACTANT HAVING AT LEAST ONE -N=C=X GROUP (WHEREIN X IS A CHALCOGEN ATOM) AS WELL AS PRECURSORS THEREOF, E.G., BLOCKED ISOCYANATE, ETC.
 This subclass is indented under subclass 1.  Subject matter under Class 520 ... involving polymers derived from a reactant containing a -N=C=X group wherein X is a chalcogen atom (i.e., O, S, Se, or Te) or processes of polymerizing; polymerizable compositions containing as a reactant a compound having the general formula R-N=C=X wherein X is a chalcogen or processes of preparing a polymerizable composition.
(1) Note. This subclass also provides for those functional derivatives of isocyanates which are generally known as blocked, masked, or hidden isocyanates. These materials are those which revert on heating to the -N=C=X group (e.g., urethanes or ureides of phenols, alkanols, lactams, oximes, etc.)
(2) Note. Where a -N=C=X group is produced by an in situ reaction or a decomposition reaction (other than blocked, masked, or hidden isocyanates), those patents have been placed as originals in subclasses which provide for the compound prior to its decomposition or on the basis of the reactants undergoing the in situ reaction (e.g., adiponitrile, carbonates, or oxalates).
(3) Note. Polonium is excluded from this subclass as being a chalcogen.
(4) Note. As used throughout this subclass any reference to X (e.g., -XH-C-XH, etc.) connotes oxygen, sulfur, selenium, or tellurium.

SEE OR SEARCH THIS CLASS, SUBCLASS:

370+,
480+,for processes of preparing a polymer not involving a chemical modification of the polymer, by the addition of a material thereto, and for chemically modifying material other than the polymer. Subclasses 480+ also provide for processes of admixing with a broadly claimed nonreactant material.
  
[List of Patents for class 528 subclass 45]    45From at least one blocked -N=C=X group
 This subclass is indented under subclass 44.  Subject matter wherein at least one material having a -N=C=X group which has been rendered inert by conversion to an inactive group (e.g., blocked, masked, or hidden) is utilized as a reactant.
(1) Note. The reaction process usually involves heating the reactant which thereby reverts to a -N=C=X-containing reactant.
(2) Note. The -N=C=X group which has been rendered inert is usually in the form of a urethan group
  
[List of Patents for class 528 subclass 48]    48Process of polymerizing in the presence of a specified material other than reactant
 This subclass is indented under subclass 44.  Subject matter wherein a -N=C=X-containing reactant, wherein X is a chalcogen atom, i.e., O, S, Se, or Te, is polymerized in the presence of a specified material.
(1) Note. For purposes of this subclass, a compound having a single -C-XH, -C-NH2-C-NHR, or (X is chalcogen) is always considered to be a nonreactant. Similarly, a compound having a single group is considered as a nonreactant except where the compound is a fatty acid or salt derived from a naturally occurring glyceride, tall oil, or a fatty acid derived from tall oil, in which case, if the compound is a reactant it is considered proper for Class 528, subclass 74.5.
(2) Note. For purposes of this subclass a compound having two or more or (X is chalcogen) or combination of functional groups is always considered to be a reactant.

SEE OR SEARCH CLASS:

520Synthetic Resins or Natural Rubbers,   see the Glossary for an explanation of the term "specified material".
  
[List of Patents for class 528 subclass 49]    49Material contains only one -C-XH,-C-C(=X)-XH or carbon to -NH or HNH group
 This subclass is indented under subclass 48.  Subject matter wherein the specified material contains a compound having a single C-XH, C-NH2, C-NH-, or group (X is chalcogen).
  
[List of Patents for class 528 subclass 50]    50Material contains compound having a -O-O- group, e.g., peroxide, etc.
 This subclass is indented under subclass 48.  Subject matter wherein the specified material contains a compound having at least one -O-O- group (i.e., peroxide, etc.).
  
[List of Patents for class 528 subclass 51]    51Material contains a phosphorus atom
 This subclass is indented under subclass 48.  Subject matter wherein the specified material contains at least one atom of phosphorus.
  
[List of Patents for class 528 subclass 52]    52Material is organic nitrogen-containing compoud
 This subclass is indented under subclass 48.  Subject matter wherein the specified material contains at least one nitrogen-containing organic compound.
  
[List of Patents for class 528 subclass 53]    53Organic nitrogen compound contains a nitrogen atom bonded to three atoms or carbon
 This subclass is indented under subclass 52.  Subject matter wherein the organic nitrogen-containing compound possesses at least one trivalent nitrogen atom which is bonded to three atoms of carbon i.e., (C )3N
  
[List of Patents for class 528 subclass 54]    54Nitrogen compound wherein nitrogen atom is bonded to three atoms of carbon contains a bridged- or fused-ring system, e.g., triethylene diamine, etc.
 This subclass is indented under subclass 53.  Subject matter wherein the nitrogen compound whose nitrogen atom is bonded to three atoms of carbon, contains a fused- or bridged-ring system (e.g., triethylene diamine, etc.).
(1) Note. A bridged or fused ring system for purposes of this subclass requires that a ring system be attached at two different atoms of its nuclear skeleton to an atom or chain of atoms which, when taken together with the nuclear atoms, forms an additional ring structure.
  
[List of Patents for class 528 subclass 55]    55Material contains at least one metal atom
 This subclass is indented under subclass 48.  Subject matter wherein the specified material contains at least one metal atom.

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520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "metals".
  
[List of Patents for class 528 subclass 56]    56Material contains a transition metal atom
 This subclass is indented under subclass 55.  Subject matter wherein the specified material contains a transition metal atom.
(1) Note. Transition metal is limited to elements of atomic numbers 21-29, 39-47, 57-79, and 89 and higher, but does not include Zn, Cd, or Hg.
  
[List of Patents for class 528 subclass 57]    57Material contains at least one group IA or group IIA metal atom
 This subclass is indented under subclass 55.  Subject matter wherein the specified material contains at least one atom of Group IA or Group IIA metal atom.
(1) Note. Group IA metal atoms are limited to Li, Na, K, Rb, Cs, Fr. Group IIA metal atoms are limited to Be, Mg, Ca, Sr, Ba, Ra.
  
[List of Patents for class 528 subclass 58]    58Material contains at least one atom of tin
 This subclass is indented under subclass 55.  Subject matter wherein the specified material contains tin (At. No. 50).
  
[List of Patents for class 528 subclass 59]    59From N=C=X reactant having at least two -C-NH-C(=X)- groups
 This subclass is indented under subclass 44.  Subject matter wherein the -N=C=X (X is chalcogen) reactant contains at least two groups.
(1) Note. Patents for the most part herein are drawn to the after treatment of a liquid prepolymer having terminal -N=C=X groups.
(2) Note. The addition of materials to a prepolymer intermediate characterized by terms such as chain extenders, chain-lengthening material, cross-linking or curing agents, is not sufficient absent an amount of a material of chemical identity of added material (chemical identity is identical to what is required of a specified material).
(3) Note. For purposes of this subclass a carboxylic acid anhydride is considered as having two free carboxylic acid groups.

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67,through 85, for products and processes where a prepolymer is inherently prepared in an ongoing polymerization reaction and is subsequently modified, but where no intent has been made to recognize or identify the prepolymer intermediate.
  
[List of Patents for class 528 subclass 60]    60With reactant compound containing three or more XH, -C(=X)-XH, -NH, =NH, or HNH groups or combination thereof
 This subclass is indented under subclass 59.  Subject matter wherein a material containing at least one -N=C=X (X is chalcogen) group and two or more groups is reacted with a material which contains a compound having three or more -XH, NH, -NH2, C=NH or groups or contains a compound having a combination of three or more of these groups.
(1) Note. In all cases each of the functional derivatives -XH, NH, -NH2, C=NH, must be directly bonded to a carbon atom. It is permissible, however, for these functional derivatives to be bonded to different carbon atoms or to the same carbon atom. A compound having three functional derivatives bonded to a single carbon atom meets the requirement of this subclass. An anhydride formed from two carboxylic acids is considered for purposes of this subclass as having two groups.
  
[List of Patents for class 528 subclass 61]    61With organic nitrogen reactant which contains two NH, =NH, or HNH groups
 This subclass is indented under subclass 59.  Subject matter wherein a material containing at least one -N=C=X (X is chalcogen) group and two or more groups is reacted with a compound which contains two nitrogen atoms as -NH, -NH2, or =NH groups or a combination thereof.
(1) Note. In all cases each of the functional derivatives (i.e., -NH, =NH, or -NH2) must be directly bonded to different carbon atoms or to the same carbon atom. A single compound having two functional groups bonded to a single carbon atom meets the requirements of this subclass.
  
[List of Patents for class 528 subclass 62]    62Organic NH, =NH, or HNH nitrogen-containing reactant contains a heterocyclic ring
 This subclass is indented under subclass 61.  Subject matter wherein the reactant which contains two -NH, =NH, or -NH2 groups also contains a heterocyclic ring.

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520Synthetic Resins or Natural Rubbers,   see the Glossary for a definition of the term "heterocyclic".
  
[List of Patents for class 528 subclass 63]    63Organic NH, =NH, HNH nitrogen reactant contains at least one halogen atom
 This subclass is indented under subclass 61.  Subject matter wherein the -NH, NH2, or =NH reactant contains at least one halogen atom.