Described herein is a method for joining a first metal pipe with a second metal pipe, the pipes being joined together in an overlapping area by use of a two-component polyurethane adhesive that encapsulates the overlapping area, where the method includes the steps of:

(1) applying the two-component polyurethane adhesive onto an inner surface of a fixture;
(2) inserting one end of the first metal pipe into one end of the second metal pipe so as to form a pipe assembly having the overlapping area between the two ends, and putting the overlapping area of the pipe assembly into the fixture; (3) closing the fixture such that the overlapping area of the pipe assembly is fixed in the fixture, and such that the adhesive therein encapsulates the overlapping area of the pipe assembly; (4) curing the two-component polyurethane adhesive; and (5) optionally, removing the fixture from the pipe assembly.

Described herein is a method for joining a first metal pipe with a second metal pipe, the pipes being joined together in an overlapping area by use of a two-component polyurethane adhesive that encapsulates the overlapping area, where the method includes the steps of:

(1) applying the two-component polyurethane adhesive onto an inner surface of a fixture;
(2) inserting one end of the first metal pipe into one end of the second metal pipe so as to form a pipe assembly having the overlapping area between the two ends, and putting the overlapping area of the pipe assembly into the fixture; (3) closing the fixture such that the overlapping area of the pipe assembly is fixed in the fixture, and such that the adhesive therein encapsulates the overlapping area of the pipe assembly; (4) curing the two-component polyurethane adhesive; and (5) optionally, removing the fixture from the pipe assembly.

A polyurethane composition includes, based on the total weight of the composition, A) 20-35 wt % of polyurethane prepolymer PU-1 which is a reaction product of ethylene oxide (EO)-terminated polyether triol with an aromatic polyisocyanate, and B) 0.2-3 wt % of polyurethane prepolymer PU-2 which is a reaction product of polyester polyol with an aromatic polyisocyanate. The composition has a low TVOC content, has a good adhesion without the need of primer, can cure rapidly with a high initial bonding strength, while keeping good mechanical properties.

A polyurethane composition includes, based on the total weight of the composition, A) 20-35 wt % of polyurethane prepolymer PU-1 which is a reaction product of ethylene oxide (EO)-terminated polyether triol with an aromatic polyisocyanate, and B) 0.2-3 wt % of polyurethane prepolymer PU-2 which is a reaction product of polyester polyol with an aromatic polyisocyanate. The composition has a low TVOC content, has a good adhesion without the need of primer, can cure rapidly with a high initial bonding strength, while keeping good mechanical properties.

A urethane-based adhesive composition includes a urethane prepolymer, a carbon black A having a dibutyl phthalate oil absorption number of 30 to 40 ml/100 g, a carbon black B having a dibutyl phthalate oil absorption number of 98 to 108 ml/100 g, a calcium carbonate C, a plasticizer D, a modified product E of an aliphatic diisocyanate, and a catalyst, and the urethane-based adhesive composition is configured to satisfy all of the following (1) to (6): (1) 25≤a≤35, (2) 55≤b≤75, (3) 197≤a+3b≤251, (4) 30≤c≤35, (5) 35≤d≤45, and (6) 9≤e≤13.

A urethane-based adhesive composition includes a urethane prepolymer, a carbon black A having a dibutyl phthalate oil absorption number of 30 to 40 ml/100 g, a carbon black B having a dibutyl phthalate oil absorption number of 98 to 108 ml/100 g, a calcium carbonate C, a plasticizer D, a modified product E of an aliphatic diisocyanate, and a catalyst, and the urethane-based adhesive composition is configured to satisfy all of the following (1) to (6): (1) 25≤a≤35, (2) 55≤b≤75, (3) 197≤a+3b≤251, (4) 30≤c≤35, (5) 35≤d≤45, and (6) 9≤e≤13.

Disclosed is a polyurethane hot-melt adhesive including: a thermoplastic polyurethane that is a reactant of a raw material including a polymer polyol, a polyisocyanate, and a chain extender, wherein X−Y≥15, where X represents a temperature (° C.) at which the polyurethane hot-melt adhesive has a melt viscosity of 2.0×10.sup.3 Pa.Math.s, and Y represents a temperature at which the polyurethane hot-melt adhesive has a melt viscosity of 1.0×10.sup.5 Pa.Math.s, and the polyurethane hot-melt adhesive has a 100% modulus of 2.5 MPa or more.

Disclosed is a polyurethane hot-melt adhesive including: a thermoplastic polyurethane that is a reactant of a raw material including a polymer polyol, a polyisocyanate, and a chain extender, wherein X−Y≥15, where X represents a temperature (° C.) at which the polyurethane hot-melt adhesive has a melt viscosity of 2.0×10.sup.3 Pa.Math.s, and Y represents a temperature at which the polyurethane hot-melt adhesive has a melt viscosity of 1.0×10.sup.5 Pa.Math.s, and the polyurethane hot-melt adhesive has a 100% modulus of 2.5 MPa or more.

The present invention provides a resin composition for an adhesive, being useful as a component of an adhesive having a favorable adhesion property to glass and giving favorable appearance after adhesion. The resin composition for an adhesive contains a polyhydroxyurethane resin. This polyhydroxyurethane resin contains a structural unit formed by polymerizing a compound (A) having at least two five-membered cyclic carbonate structures and a compound (B) having at least two primary amino groups, the polyurethane resin contains a urethane bond, a hydroxy group, and a secondary amino group in the structural unit. Further, this polyhydroxyurethane resin has an amine number of 1 to 50 mgKOH/g and has a hydroxyl number of 10 to 230 mgKOH/g.

A two-component composition is described which comprises A) an isocyanate component comprising an isocyanate-terminated urethane prepolymer, B) a water component comprising water, and at least one latent amine hardener in component A). The two-component composition of the invention is suitable as a sealant, in particular as a joint sealant. Particular advantages are that primerless application is possible with good adhesion, even at low temperatures, such as 4.4° C. or below. The substrate to be sealed are preferably concrete substrates.