JP-7857237-B2 - Mixtures and curable compositions of polyoxyalkylene polymers

Inventors

• 佐藤 章徳

Assignees

• 株式会社カネカ

Dates

Publication Date

20260512

Application Date

20220124

Priority Date

20210129

Claims (9)

1. Both are mixtures of polyoxyalkylene polymers (A) and (B) having hydrolyzable silyl groups, The polyoxyalkylene polymer (A) has two or more molecular chain ends containing a hydrolyzable silyl group or a reactive group capable of introducing a hydrolyzable silyl group, The average ratio of the number of hydrolyzable silyl groups located at the molecular chain ends of the polyoxyalkylene polymer (A) to the number of molecular chain ends of the polyoxyalkylene polymer (A) is 0.90 or more and 1.00 or less. The number average molecular weight of the polyoxyalkylene polymer (A) is 25,000 or less. The hydrolyzable silyl group in the polyoxyalkylene polymer (A) is of general formula (1): -SiR 1 X 1 2 (1) (In the formula, R 1 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. X 1 represents a hydroxyl group or a hydrolyzable group, either the same or different.) The polyoxyalkylene polymer (B) has one hydrolyzable silyl group or a molecular chain terminal containing a reactive group to which a hydrolyzable silyl group can be introduced in each molecule. The number-average molecular weight of the polyoxyalkylene polymer (B) is smaller than the number-average molecular weight of the polyoxyalkylene polymer (A), The hydrolyzable silyl group of the polyoxyalkylene polymer (B) is of general formula (1'): -SiR 2 a X 2 3-a (1') (In the formula, R 2 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. X 2 represents a hydroxyl group or a hydrolyzable group, either the same or different. a represents 0, 1, or 2. However, the hydrolyzable silyl group having the polyoxyalkylene polymer (B) may be the same as or different from the hydrolyzable silyl group having the polyoxyalkylene polymer (A).) A mixture in which the mixing ratio of the polyoxyalkylene polymers (A) and (B) is 95:5 to 30:70 by weight.
2. The mixture according to claim 1, wherein the polyoxyalkylene polymer (A) has a linear polymer backbone.
3. The mixture according to claim 1 or 2, wherein the viscosity of the mixture at 23°C is less than 15 Pa·s.
4. The mixture according to any one of claims 1 to 3, wherein a in the general formula (1') represents 1.
5. The mixture according to any one of claims 1 to 4, wherein the number average molecular weight of the polyoxyalkylene polymer (B) is 10,000 or less.
6. The mixture according to any one of claims 1 to 5, wherein the average ratio of the number of hydrolyzable silyl groups located at the molecular chain ends of the polyoxyalkylene polymer (B) to the number of molecular chain ends of the polyoxyalkylene polymer (B) is 0.50 or more and 1.00 or less.
7. A curable composition containing the mixture described in any one of claims 1 to 6.
8. A cured product of the curable composition described in claim 7.
9. A method for producing the mixture according to any one of claims 1 to 6, A step of polymerizing an epoxy compound in the presence of a mixture of an initiator having two or more hydroxyl groups in one molecule and an initiator having one hydroxyl group in one molecule, thereby forming a mixture of polyoxyalkylene polymers having hydroxyl groups at the ends of the molecular chains, A method for producing the aforementioned polyoxyalkylene polymer, comprising the step of introducing a hydrolyzable silyl group to the molecular chain terminus.

Description

The present invention relates to a mixture of polyoxyalkylene polymers having hydrolyzable silyl groups, and a curable composition containing the mixture. Polymers containing hydrolyzable silyl groups are known as moisture-reactive polymers and are found in many industrial products such as adhesives, sealants, coatings, paints, and tacks, and are used in a wide range of fields. Known main chain skeletons for such polymers include polyoxyalkylene polymers, saturated hydrocarbon polymers, and (meth)acrylic acid ester polymers. In particular, polyoxyalkylene polymers having hydrolyzable silyl groups (see, for example, Patent Document 1) have relatively low viscosity at room temperature, making them easy to handle, and the cured product obtained after the reaction exhibits good elasticity, thus giving them a wide range of applications. On the other hand, in recent years, the construction market has been seeking sealants that are less prone to bleed-out. Therefore, in curable compositions for sealants containing polyoxyalkylene polymers with hydrolyzable silyl groups, methods are being investigated that do not use conventional phthalate ester plasticizers or PPG plasticizers, but instead incorporate reactive diluents with introduced hydrolyzable silyl groups (see, for example, Patent Documents 2 and 3). Japanese Unexamined Patent Publication No. 52-73998Japanese Patent Publication No. 2018-104670International Publication No. 2020/066551 Embodiments of the present invention will be described in detail below. (A mixture of polyoxyalkylene polymers (A) and (B)) The mixture according to this embodiment comprises a polyoxyalkylene polymer (A) having a hydrolyzable silyl group, and a polyoxyalkylene polymer (B) having a hydrolyzable silyl group. The mixture according to this embodiment refers to a mixture that substantially contains only the polyoxyalkylene polymers (A) and (B). The mixture exhibits curability based on hydrolysis and dehydration condensation reactions of the hydrolyzable silyl groups, as the polyoxyalkylene polymers (A) and (B) each have a hydrolyzable silyl group. Polyoxyalkylene polymers (A) and (B) each have a polyoxyalkylene polymer backbone and molecular chain ends bonded to the polymer backbone. The polymer backbone and the molecular chain ends may be directly bonded or indirectly bonded via an intermediate structure. Examples of the intermediate structure include structures derived from the epoxy compound (G3) described later (i.e., the n structures in parentheses in formula (4) described later). The polymer skeleton refers to the polymer main chain composed of oxyalkylene repeating units. The polymer skeletons of polyoxyalkylene polymers (A) and (B) may be linear or branched. A linear polymer skeleton is preferred in that the cured product of the curable composition has high elongation, while a branched polymer skeleton is preferred in that the cured product of the curable composition has high strength. A linear polymer skeleton can be formed by using an initiator having one or two hydroxyl groups per molecule in the polymerization method for forming the polymer skeleton, and a branched polymer skeleton can be formed by using an initiator having three or more hydroxyl groups per molecule. The polymer skeleton is preferably composed solely of a plurality of interconnected oxyalkylene repeating units, or, in addition to the plurality of oxyalkylene repeating units, a structure derived from an initiator used during polymerization is included, and the polymer skeleton is composed solely of these. Here, the oxyalkylene repeating unit refers to a repeating unit constituting a polyether, and for example, an oxyalkylene unit having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms. The polymer skeleton of the polyoxyalkylene is not particularly limited, but examples include polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymer, and polyoxypropylene-polyoxybutylene copolymer. Polyoxypropylene is preferred. Only one polymer skeleton may be used, or two or more may be used in combination. The aforementioned molecular chain end refers to the region located at the end of a polyoxyalkylene polymer. The molecular chain ends are classified into three categories: molecular chain ends containing a hydrolyzable silyl group, molecular chain ends containing a reactive group capable of introducing a hydrolyzable silyl group, or molecular chain ends that do not contain either a hydrolyzable silyl group or the aforementioned reactive group. The reactive group capable of introducing a hydrolyzable silyl group refers to a reactive group that can be converted to a hydrolyzable silyl group through one or more reaction steps. Specific examples of such reactive groups are not particularly limited, but include, for example, hydroxyl groups and carbon-carbon unsaturated bonds (carbon-carbon double bonds or carbon-carbon triple bonds). Polyoxyalkylene polymers