content_image/900151.jpg content_image/900150.jpg
and Rs$_{6 }$ may be bonded to each other to form a ring. However, Rss and Rs$_{6 }$ do not represent a hydrogen atom at the same time in any case. 

General Formula (V) will be described in more detail. 

Examples of the alkyl group of each of Rsi to Rs$_{3 }$ in General Formula (V) preferably include an alkyl group having 20 or less carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a hexyl group, a 2-ethylhexyl group, an octyl group, and a dodecyl group, which may have a substituent, more preferably include an alkyl group having 8 or less carbon atoms, and particularly preferably include an alkyl group having 3 or less carbon atoms. 

The alkyl group included in an alkoxycarbonyl group is preferably the same alkyl group as that in each ofRsi to Rs$_{3 }$ described above. 

The cycloalkyl group may be monocyclic or polycyclic. Preferred examples thereof include a monocyclic cycloalkyl group having 3 to 10 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group, which may have a substituent. 

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, with the fluorine atom being particularly preferable. 

Preferred examples of the substituent in each group described above can include an alkyl group, a cycloalkyl group, an aryl group, an amino group, an amido group, a ureido group, a urethane group, a hydroxyl group, a carboxyl group, a halogen atom, an alkoxy group, a thioether group, an acyl group, an acyloxy group, an alkoxycarbonyl group, a cyano group, and a nitro group, and the substituent preferably has 8 or less carbon atoms. 

Furthermore, in a case where Rs$_{2 }$ represents an alkylene group and is bonded to Ls to form a ring, preferred examples of the alkylene group include an alkylene group having 1 to 8 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a butylene group, a hexylene group, and an octylene group. The alkylene group is more preferably an alkylene group having 1 to 4 carbon atoms, and particularly preferably an alkylene group having 1 or 2 carbon atoms. A ring formed by the bonding of Rs$_{2 }$ and Ls is particularly preferably a 5- or 6-membered ring. 

Rsi and Rs$_{3 }$ in Formula (V) are each more preferably a hydrogen atom, an alkyl group, or a halogen atom, and particularly preferably a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group (----CF$_{3}$ ), a hydroxym› ethyl group (----CH$_{2}$ ---0H), a chloromethyl group (----CH$_{2}$ - Cl), or a fluorine atom (-F). Rs$_{2 }$ is more preferably a hydrogen atom, an alkyl group, a halogen atom, or an alkylene group (which is bonded to Ls to form a ring), and particularly preferably a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group (----CF$_{3}$ ), a hydroxym› ethyl group (----CH$_{2}$ ---0H), a chloromethyl group (----CH$_{2}$ - Cl), a fluorine atom (-F), a methylene group (which is bonded to Ls to form a ring), or an ethylene group (which is bonded to Ls to form a ring). 

Examples of the divalent linking group represented by Ls include an alkylene group, a divalent aromatic cyclic group, -COO-Li-, ---0-Li-, and a group formed by combining two or more thereof. Here, Li represents an alkylene group, a cycloalkylene group, a divalent aromatic cyclic group, and a group formed by combining an alkylene group with a divalent aromatic cyclic group. 

Ls is preferably a single bond, a group represented by -COO-Li-, or a divalent aromatic cyclic group. Li is preferably an alkylene group having 1 to 5 carbon atoms, and more preferably a methylene group or a propylene 

group. The divalent aromatic cyclic group is preferably a 1,4-phenylene group, a 1,3-phenylene group, a 1,2-phe› nylene group, or a 1,4-naphthylene group, and more pref› erably a 1,4-phenylene group. 

Suitable examples of the trivalent linking group repre› sented by Ls in a case where Ls is bonded to Rs$_{2 }$ to form a ring include a group obtained by eliminating arbitrary one hydrogen atom from the above-described specific examples of the divalent linking group represented by Ls- 

The alkyl group of each of Rs$_{4 }$ to Rs$_{6 }$ is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and particularly preferably an alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group. 

The cycloalkyl group represented by each ofRss and Rs$_{6 }$ is preferably a cycloalkyl group having 3 to 20 carbon atoms, may be a cycloalkyl group which is monocyclic, such as a cyclopentyl group and a cyclohexyl group, and may be a cycloalkyl group which is polycyclic, such as a norbomyl group, an adamantyl group, a tetracyclodecanyl group, and a tetracyclododecanyl group. 

Furthermore, the ring formed by the mutual bonding of Rss and Rs$_{6 }$is preferably a ring having 3 to 20 carbon atoms, may be monocyclic, such as a cyclopentyl group and a cyclohexyl group, and may be the ring which is polycyclic, such as a norbornyl group, an adamantyl group, a tetracy› clodecanyl group, and a tetracyclododecanyl group. In a case where Rss and Rs$_{6 }$ are bonded to each other to form a ring, Rs$_{4 }$ is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group. 

The aryl group represented by each of Rss and Rs$_{6 }$ is preferably an aryl group having 6 to 20 carbon atoms, may be monocyclic or polycyclic, or may have a substituent. Examples thereof include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 4-methylphenyl group, and a 4-methoxyphenyl group. In a case where any one ofRss and Rs$_{6 }$ is a hydrogen atom, the other is preferably an aryl group. 

The aralkyl group represented by each ofRss and Rs$_{6 }$ may be monocyclic or polycyclic, or may have a substituent. The aralkyl group preferably has 7 to 21 carbon atoms, and examples thereof include a benzyl group and a 1-naphthyl› methyl group. 

The side chain structure included in the repeating unit (a) is preferably represented by General Formula (S). 

(In the formula, wi represents a group capable of leaving by an acid, and L represents a linking group formed of a polyvalent non-metal atom which is necessary to link a structural unit represented by General Formula (S) to a polymer skeleton.) 

That is, in General Formula (S), the moiety represented by -L-SO$_{3}$ - represents a moiety capable of generating a sul› fonic acid group as the leaving group represented by wi at the terminal leaves, L is a polyvalent linking group formed of a non-metal atom, and more specific examples of the moiety include those configured by the combination of the following structural units. 

<img src='content_image/900151.jpg'>

<img src='content_image/900150.jpg'>

