Evaluating moisture resistance reliability of phosphonium borate catalyst

A method of evaluating the moisture resistance reliability of a latent catalyst to determine whether the latent catalyst is suitable for thermosetting resin compositions, the method comprising:

• (1) providing a latent catalyst, derived from at least one proton donor, which latent catalyst corresponds to a member selected from the group consisting of:
• (a) the general formula (I):
• wherein R1, R2, R3 and R4 may be the same as or different from one another and each is a monovalent organic group having an aromatic ring or a heterocyclic ring or a monovalent aliphatic group, and is bonded to the phosphorus atom to form a P—C bond, and
• wherein X1, X2, X3 and X4 may be the same as or different from one another, and at least one of which is a group formed when a proton donor having at least one proton capable of being liberated out of the molecule has liberated one proton, and each of the others is a monovalent organic group having an aromatic ring or a heterocyclic ring or a monovalent aliphatic group;
• (b) the general formula (II):
• wherein R5, R6, R7 and R8 may be the same as or different from one another and each is a monovalent organic group having an aromatic ring or a heterocyclic ring or a mono-valent aliphatic group, and is bonded to the phosphorus atom to form a P—C bond,
• Z1 is an organic group bonding to Y1 and Y2, and Z2 is an organic group bonding to Y3 and Y4,
• each of Y1 and Y2 is a group formed when a monovalent, proton-donor has liberated a proton, and the substituents Y1 and Y2 in the same molecule are bonded to the boron atom to form a chelate structure,
• each of Y3 and Y4 is a group formed when a monovalent, proton-donor has liberated a proton, and the substituents Y3 and Y4 are bonded to the boron atom to form a chelate structure,
• Z1 and Z2 are the same as or different from each other, and Y1 and Y2, and Y3 and Y4 may be the same as or different from one another, and
• wherein the formulas H Y1 Z1 Y2 H and H Y3 Z2 Y4H correspond to proton donors before the ligands Y1 Z1 Y2 and Y3 Z2 Y4 of boron are formed by liberation of the respective protons;
• (c) the general formula (III):
• wherein R9, R10, R11 and R12 may be the same as or different from one another, and each is a monovalent organic group having an aromatic ring or a heterocyclic ring or a monovalent aliphatic group, and is bonded to the phosphorus atom to form a P—C bond,
• Z3 is an organic group bonding to the substituents Y5 and Y6, Y5 and Y6 may be the same as or different from each other, and each is a group formed when a monovalent proton-donor has liberated a proton, and the substituents Y5 and Y6 in the same molecule are bonded to the boron atom to form a chelate structure, and
• X5 and X6 may be the same as or different from each other, and each is a group formed when a proton donor having at least one proton capable of being liberated out of the molecule has liberated one proton, or is a monovalent organic group having an aromatic ring or a heterocyclic ring or a monovalent aliphatic group, and
• wherein the formula H Y5 Z3 Y6 H corresponds to a proton donor before the ligand Y5 Z3 Y6 of boron is formed by the liberation of the protons, and wherein HX5 and HX6 are proton donors in the case where each of X5 and X6 is a group formed when a proton donor having at least one proton capable of being liberated out of the molecule has liberated one proton;
• and
• (d) a compound having a structure of recurring units in which the recurring unit is a phosphonium borate consisting of a monovalent cation portion in which four groups are bonded to the phosphorus atom and a monovalent anion portion in which four groups are bonded to the boron atom,
• wherein at least two of the recurring units are connected through at least one of the four groups bonding to the boron atom, and wherein the group through which the recurring units are connected is a group formed when a proton donor has liberated at least two protons,
• wherein the groups bonding to the phosphorus atom may be the same as or different from one another, and each is a monovalent, organic group having an aromatic ring or a heterocyclic ring or a monovalent aliphatic group, and is bonded to the phosphorus atom to form a P—C bond;
• and
• wherein, among the groups bonding to the boron atom, those which do not participate in the connection of the recurring units are each a group formed when a proton donor having at least one proton capable of being liberated out of the molecule has liberated one proton, or a monovalent organic group having an aromatic ring, or a heterocyclic ring or a monovalent aliphatic group, which groups may be the same as or different from one another;
• (2) mixing 1 gram of the proton donor from which the latent catalyst is derived with 50 grams of purified water to obtain an aqueous mixture;
• (3) subjecting the aqueous mixture to pressure cooker treatment at a temperature of 125° C. for 20 hours in a pressure cooker vessel to obtain an extraction mixture;
• and
• (4) measuring the electrical conductivity of the extraction mixture to determine whether the electrical conductivity of the extraction mixture is greater than 1,000 μS/cm,
• wherein the electrical conductivity of an extraction mixture obtained from a proton donor of a catalyst suitable for thermosetting resin compositions is no greater than 1,000 μS/cm.