May 5, 2011  11  US 2011/0104454 Al  [0122]  Regarding the polymerization degree, the specific  polymer according to the invention is preferably a 20-mer or  more, more preferably a 30-mer or more. Further, the specific  polymer according to the invention is preferably a 1,500-mer  or less, more preferably a 1,000-mer or less.  [0123]  In the composition for forming a layer to be plated  according to the invention, a mixed solvent of water and  water-soluble flarmnable liquid is used as a solvent, as  described below.  [0124]  The specific polymer described above is preferably  contained in the range of from 1 % by mass to 20% by mass,  and more preferably from 2% by mass to 10% by mass, with  respect to a total amount of the composition.  [0125]  Mixed Solvent Containing from 20% By Mass to  99% By Mass ofWater-Soluble Flammable Liquid and Water  [0126]  The composition for forming a layer to be plated  according to the invention contains, as well as a specific  polymer described above, a mixed solvent containing both a  water-soluble flammable liquid and water, which is capable  of dissolving the specific polymer.  It  is necessary that the  mixed solvent containing the water-soluble flammable liquid  and water used in the invention contains from 20% by mass to  99% by mass of the water-soluble flarmnable liquid in terms  of a total solvent. Herein, a mixed solvent in which the  remainder other than the water-soluble flammable liquid is  water is preferred. The content of the water-soluble flam› mable liquid in the mixed solvent is preferably in the range of  from 30% by mass to 80% by mass, and more preferably from  35% by mass to 60% by mass.  [0127]  The water-soluble flammable liquid used in the  mixed solvent of the water-soluble flammable liquid and  water is not specifically limited, so long as the flammable  liquid dissolves 1 % by mass or more thereof in water at  ordinary temperature (25°  C.). Further, the flammable liquid  described in the present specification refers to flammable  liquids as recited in the Fire Services Act.  Water-Soluble Flammable Liquid  [0128]  Examples of the water soluble flammable solvent  include organic solvents such as ketone-based solvents, ester› based solvents, alcohol-based solvents, ether-based solvents,  amine-based solvents, thiol-based solvents and halogen› based solvents.  [0129]  Examples of the ketone-based solvents include  4-hydroxy-4-methyl-2-pentanone,  y-butyrolactone  and  hydroxyacetone.  [0130]  Examples of the ester-based solvents include 2-(2- ethoxyethoxy)ethyl acetate, ethylene glycol monomethyl  ether acetate, diethylene glycol monoethyl ether acetate,  methyl cellosolve acetate, 2-hydroxyethyl acrylate, hydrox› ypropyl acrylate, methyl glycolate and ethyl glycolate.  [0131]  Examples of the alcohol-based solvent include  methanol, ethanol, l-methoxy-2-propanol, isopropyl alco› hol, normal propyl alcohol, 3-acetyl-1-propanol, 2-(allyloxy)  ethanol, 1-pentanol, 3-methyl-1-butanol, n-hexanol, 1-hep› tanol, 2-ethyl-1,3-hexanediol, 2-aminoethanol, 2-amino-2- methyl-1-propanol,  (–)-2-amino-l-propanol,  3-amino-1- propanol, 2-dimethylaminoethanol, 2,3-epoxy-l-propanol,  ethylene glycol, 2-fluoroethanol, diacetone alcohol, 2-meth› ylcyclohexanol, 4-hydroxy-4-methyl-2-pentanone, glycerin,  2,2’,2"-nitrilotriethanol, 2-pyridine methanol, 2,2,3,3-tet› rafluoro-l-propanol, 2-(2-aminoethoxy)ethanol, 2-[2-(ben› zyloxy)ethoxy]ethanol,  2,3-butanediol,  2-butoxyethanol,  2,2’-thiodiethanol, 1,3-butanediol, 1,4-butanediol, 2,3-bu- tanediol, 2-methyl-2,4-pentanediol, 1,3-propanediol, diglyc› erin, 2,2’-methyliminodiethanol and 1,2-pentanediol. In addi› tion, the alcohol-based solvent includes alcohol derivatives  such as 3-amino-1-propanol, trifluoroethyl methacrylate, and  pentadecafluoro octanol.  [0132]  Examples of the ether-based solvent include bis(2- ethoxyethyl)ether, bis[2-(2-hydroxyethoxy)ethyl]ether, 1,2- bis(2-methoxyethoxy )ethane,  bis [2-(2-methoxyethoxy)  ethyl]ether, bis(2-methoxyethyl)ether, 2-(2-butoxyethoxy)  ethanol,  2-[2-(2-chloroethoxy )ethoxy ]ethanol,  2-ethoxyethanol, 2-(2-ethoxyethoxy)ethanol, 2-isobutoxy  ethanol, 2-(2-isobutoxyethoxy)ethanol, 2-isopropoxyetha› nol, 2-[2-(2-methoxyethoxy)ethoxy]ethanol, 2-(2-methoxy› ethoxy)ethanol,  l-ethoxy-2-propanol,  l-methoxy-2-pro› panol, tripropylene glycol monomethyl ether, methoxy  acetate and 2-methoxy ethanol.  [0133]  Examples of the glycol-based solvents include  diethylene glycol, triethylene glycol, ethylene glycol, hexa› ethylene glycol, propylene glycol, dipropylene glycol and  tripropylene glycol.  [0134]  Examples of the amine-based solvent include  N-methyl-2-pyrolidone and N,N-dimethyl formamide.  [0135]  Examples of the thiol-based solvent include mer› captoacetic acid and 2-mercaptoethanol.  [0136]  Examples of the halogen-based solvent include  3-bromobenzylalcohol, 2-chloroethanol and 3-chloro-1,2- propanediol.  [0137]  Examples of the solvent contained in the water› soluble flammable liquid other than the above-described sol› vent include methyl lactate, ethyl lactate, morpholine,  N-ethyl morpholine, formic acid, and acetic acid.  [0138]  The water-soluble flammable liquid contained in the  mixed solvent may be used singly or by mixing two or more  kinds so long as a total content of the water-soluble flam› mable liquid is in the aforementioned range.  [0139]  Water-Alcohol Mixed Solvent  [0140]  Examples of the optimal embodiment of the mixed  solvent containing both water and a water-soluble flammable  liquid includes a water-alcohol mixed solvent using an alco› hol-based solvent as the water-soluble flammable liquid.  [0141]  It  is necessary that the water alcohol solvent con› tains 20% by mass to 99% by mass of alcohol in the total  solvent. Herein, a mixed solvent is preferred in which the  remainder other than alcohol is water. The content of alcohol  in the mixed solvent is preferably in the range from 30% by  mass to 80% by mass, and more preferably from 35% by mass  to 60% by mass.  [0142]  The alcohol-based solvent used in the mixed solvent  includes the alcohols and alcohol derivatives described  above, and preferable examples include alcohol-based sol› vents such as methanol, ethanol, propanol, ethylene glycol,  glycerine, propylene glycol monomethyl ether, and l-meth› oxy-2-propanol.  [0143]  The alcohol-based solvent contained in the mixed  solvent may be used singly or by mixing two or more kinds  [0144]  Further, in a water-alcohol mixed solvent containing  alcohol and water that is an optimal solvent in the invention,  the alcohol may be used together with acids such as acetic  acid; or a ketone-based solvent such as acetone, methyl ethyl  ketone and cyclohexanone; an amide-based solvent such as  formamide, dimethyl acetamide, andN-methylpyrrolidone; a  nitrile-based solvent such as acetonitrile and propyronitrile;  an ester-based solvent such as methyl acetate and ethyl  acetate; or a carbonate-based solvent such as dimethyl car-