Defoaming agent and lubricating oil composition

1. A defoaming agent comprising:

a polymer obtainable by copolymerization of a first component and a second component;

the first component being at least one polysiloxane macromonomer selected from compounds represented by the following general formula (7) or (8); and

the second component being at least one monomer represented by the following general formula (9):

wherein

in the general formulae (7) and (8), polysiloxane repeating units may be in any order;

each of R 5 and R 6 is independently a C 1-18 organic group comprising no fluorine atom;

each of R 7 and R 8 is independently an organic group comprising no less than 3 fluorine atoms or a C 1-18 organic group comprising no fluorine atom, wherein at least one of R 7 and R 8 is the organic group comprising no less than 3 fluorine atoms;

each of Q 5 , Q 6 , and Q 7 is independently a polymerizable functional group comprising an ethylenic unsaturated group;

Z 5 is a linking group linking the polymerizable functional group Q 5 and a polysiloxane moiety;

Z 6 is a linking group linking the polymerizable functional group Q 6 and a polysiloxane moiety;

Z 7 is a linking group linking the polymerizable functional group Q 7 and a polysiloxane moiety;

T 5 is a non-polymerizable organic group;

g is an integer of no less than 0;

h is an integer of no less than 1; and

g+h is 5 to 2000,

Q 8 -Z 8 —Y 8 (9)

wherein in the general formula (9), Q 8 is a polymerizable functional group comprising an ethylenic unsaturated group;

Y 8 is a substituted or unsubstituted C 1-40 hydrocarbyl group, wherein the substituted hydrocarbyl group is a fluoroalkyl group, a fluoroalkyl (poly)ether group, or a substituted hydrocarbyl group having 1 to 3 heteroatoms,

wherein the substituted hydrocarbyl group having 1 to 3 heteroatoms is a substituted hydrocarbyl group obtainable from an unsubstituted hydrocarbyl group by substituting at least one hydrogen atom with a heteroatom-containing group, substituting at least one methylene group with ether bond, a secondary amino group, or thioether bond, or substituting at least one methine group with a tertiary amino group, or any combination thereof wherein the substituted hydrocarbyl group does not comprise three ether bonds,

wherein the heteroatom-containing group is hydroxy group, mercapto group, primary amino group, an amine residue having 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms, a heterocycle residue having 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms, or a cyclic ether group having 2 to 5 carbons; and

Z 8 is a linking group linking Q 8 and Y 8 .

2. The defoaming agent according to claim 1 ,

wherein in the first component, a ratio of a total number of polysiloxane repeating units comprising fluorine atoms to a total number of all polysiloxane repeating units is 0.01 to 1.

3. The defoaming agent according to claim 1 ,

wherein an amount of the first component in the copolymerization is 0.5 to 80 parts by mass on the basis of the total amount of the first component and the second component as 100 parts by mass.

4. The defoaming agent according to claim 1 ,

wherein Q 5 , Q 6 , and Q 7 comprise (meth)acryloyl group.

5. The defoaming agent according to claim 1 ,

wherein the polymer has a weight average molecular weight of 10,000 to 1,000,000.

6. The defoaming agent according to claim 1 ,

wherein the first component has a weight average molecular weight of 500 to 500,000.

7. A lubricating oil composition comprising:

a lubricating base oil; and

the defoaming agent as in claim 1 , in an amount of 1 to 500 mass ppm in terms of silicon on the basis of the total mass of the composition.

8. A method for lubricating an automobile engine, an automobile transmission, or an automobile transaxle unit, the method comprising:

supplying the lubricating oil composition according to claim 7 to the automobile engine, or to the automobile transmission, or to the automobile transaxle unit.

9. A defoaming agent comprising:

a polymer obtainable by copolymerization of a first component and a second component;

the first component being at least one polysiloxane macromonomer selected from compounds represented by the following general formula (7) or (8); and

the second component being at least one monomer represented by the following general formula (9):

wherein

in the general formulae (7) and (8), polysiloxane repeating units may be in any order;

each of R 5 and R 6 is independently a C 1-18 organic group comprising no fluorine atom;

each of R 7 and R 8 is independently an organic group comprising no less than 3 fluorine atoms or a C 1-18 organic group comprising no fluorine atom, wherein at least one of R 7 and R 8 is the organic group comprising no less than 3 fluorine atoms;

each of Q 5 , Q 6 , and Q 7 is independently a polymerizable functional group comprising an ethylenic unsaturated group;

Z 5 is a linking group linking the polymerizable functional group Q 5 and a polysiloxane moiety;

Z 6 is a linking group linking the polymerizable functional group Q 6 and a polysiloxane moiety;

Z 7 is a linking group linking the polymerizable functional group Q 7 and a polysiloxane moiety;

T 5 is a non-polymerizable organic group;

g is an integer of no less than 0;

h is an integer of no less than 1; and

g+h is 5 to 2000,

Q 8 -Z 8 —Y 8 (9)

wherein in the general formula (9), Q 8 is a polymerizable functional group comprising an ethylenic unsaturated group;

Y 8 is substituted or unsubstituted C 1-40 hydrocarbyl group, wherein the substituted hydrocarbyl group is a fluoroalkyl group, or a substituted hydrocarbyl group having 1 to 3 heteroatoms,

wherein the substituted hydrocarbyl group having 1 to 3 heteroatoms is a substituted hydrocarbyl group obtainable from an unsubstituted hydrocarbyl group by substituting at least one hydrogen atom with a heteroatom-containing group, substituting at least one methylene group with ether bond, a secondary amino group, or thioether bond, or substituting at least one methine group with a tertiary amino group, or any combination thereof wherein the substituted hydrocarbyl group does not comprise three ether bonds,

wherein the heteroatom-containing group is hydroxy group, mercapto group, primary amino group, an amine residue having 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms, a heterocycle residue having 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms, or a cyclic ether group having 2 to 5 carbons; and

Z 8 is a linking group linking Q 8 and Y 8 .

10. The defoaming agent according to claim 9 ,

wherein in the first component, a ratio of a total number of polysiloxane repeating units comprising fluorine atoms to a total number of all polysiloxane repeating units is 0.01 to 1.

11. The defoaming agent according to claim 9 ,

wherein an amount of the first component in the copolymerization is 0.5 to 80 parts by mass on the basis of the total amount of the first component and the second component as 100 parts by mass.

12. The defoaming agent according to claim 9 ,

wherein Q 5 , Q 6 , and Q 7 comprise (meth)acryloyl group.

13. The defoaming agent according to claim 9 ,

wherein the polymer has a weight average molecular weight of 10,000 to 1,000,000.

14. The defoaming agent according to claim 9 ,

wherein the first component has a weight average molecular weight of 500 to 500,000.

15. A lubricating oil composition comprising:

a lubricating base oil; and

the defoaming agent as in claim 9 , in an amount of 1 to 500 mass ppm in terms of silicon on the basis of the total mass of the composition.

16. A method for lubricating an automobile engine, an automobile transmission, or an automobile transaxle unit, the method comprising:

supplying the lubricating oil composition according to claim 15 to the automobile engine, or to the automobile transmission, or to the automobile transaxle unit.