Process for the adhesive bonding of plastics pipes by means of (meth)acrylate adhesive

Abstract

A process for the adhesive bonding of plastic pipes with and without a fitting by use of a (meth)acrylate adhesive and also corresponding pipe connections, are described.

Claims

1. A method for cohesively connecting plastic pipes to a fitting, comprising the steps of: (a) applying a (meth)acrylate-containing adhesive onto at least one joining surface of the fitting and/or onto at least one joining surface of the pipe ends to be connected without swelling or dissolution of at least one joining surface therewith, (b) sliding together the pipes and fitting, and (c) allowing the adhesive to cure between the joining surface(s).

2. A method for cohesively connecting plastic pipes according to claim 1, wherein the pipe connection is achieved by joining a first pipe end together with a second pipe end, wherein one pipe end represents a receiving pipe part and the other pipe end represents an insertion pipe part, wherein prior to sliding the pipe ends together, an adhesive is applied onto at least one of the joining surfaces to be connected together, and after the pipe ends have been slid together, the adhesive is allowed to cure.

3. The method according to claim 1, characterized in that the adhesive is applied by an application tool, in particular by brush coating.

4. The method according to claim 1, characterized in that the adhesive film thickness on the joining surface before assembly ranges from 0.1 mm to 3 mm.

5. The method according to claim 1, characterized in that the pipe and fitting or pipe and pipe are slid together without twisting.

6. The method according to claim 1, wherein the plastic pipes are made from thermoplastics.

7. The method according to claim 1, wherein the parts to be joined are made of different plastic materials.

8. The method according to claim 1, wherein the adhesive comprises less than 10 wt % solvent.

9. The method according to claim 1, wherein the plastic pipes are pressure pipes.

10. The method according to claim 1, wherein the pipe connection is used for one or more of potable water lines, industrial water lines, or for pressure drainage.

11. The method according to claim 1, wherein the adhesive comprises at least 40 wt % methyl acrylate.

12. The method according to claim 1, wherein the adhesive comprises at least 50 wt % methyl acrylate.

13. The method according to claim 1, wherein the adhesive comprises at least 60 wt % methyl acrylate.

14. The method according to claim 1, wherein the adhesive comprises at least 70 wt % methyl acrylate.

15. The method according to claim 1, wherein the adhesive comprises at least 90 wt % methyl acrylate.

16. The method according to claim 1, wherein the adhesive comprises less than 10 wt %, less than 5 wt %, less than 2 wt %, or no solvent.

17. The method according to claim 1, wherein the (meth)acrylate containing adhesive comprises: a) methyl methacrylate in quantities of 30 to 60 wt %, b) hydroxyethyl methacrylate, hydroxypropyl methacrylate or combinations thereof in a quantity of 5 to 15 wt %, c) methacrylic acid in quantities of 0.5 to 10 wt %, d) one or more tougheners, e) a peroxide-based curing agent in a quantity of 0.1 to 5 wt %, f) a catalyst, and g) stabilizer in a quantity of 0.1 to 15 wt %, and h) optionally thickening agents, wherein the wt % indication is based in each case on the overall composition.

18. The method according to claim 17, wherein the composition of the (meth)acrylate-containing adhesive is in a two part format in which, a first component (a) comprises: (i) methyl methacrylate in quantities of 20 to 60 wt %, based on component (a), (ii) a peroxide-based curing component in a quantity of 0.1 to 5 wt %, based on component (a), (iii) stabilizer in a quantity of 0.1 to 5 wt %, based on component (a), (iv) a toughener in a quantity of 5 to 50 %, based on component (a), (v) a thickening agent in a quantity of 0.5 to 20 wt %, based on component (a), and (vi) methacrylic acid in quantities of 1 to 5 wt %, based on component (a), and a second component (b) comprises: (i) methyl methacrylate in quantities of 10 to 90 wt %, based on component (b), (ii) a catalyst in a total quantity of 0.01 to 5 wt %, based on component (b), (iii) a stabilizer in a quantity of 0.1 to 5 wt %, based on component (b), (iv) a toughener in a quantity of 5 to 50 wt %, based on component (b), and (v) a thickening agent in a quantity of 0.5 to 20 wt %, based on component (b).

19. A pipe network made up of at least two plastic pipes with or without a fitting insert between the pipe ends, suitable for potable water lines, industrial water lines, and/or for pressure drainage, wherein the joined surfaces of the joined parts connected to one another are attached with a (meth)acrylate-containing adhesive without swelling or dissolution of the joined surfaces.

20. The pipe network according to claim 19, wherein the (meth)acrylate-containing adhesive comprises a) methyl methacrylate in quantities of 30 to 60 wt %, b) hydroxyethyl methacrylate, hydroxypropyl methacrylate or combinations thereof in a quantity of 5 to 15 wt %, c) methacrylic acid in quantities of 0.5 to 10 wt %, d) one or more tougheners to impact resistance improving components, e) a peroxide-based curing agent in a quantity of 0.1 to 5 wt %, f) a catalyst, and g) stabilizer in a quantity of 0.1 to 15 wt %, and h) optionally thickening agents, wherein the wt % indication is based in each case on the overall composition.

Description

EXAMPLE

(1) The shear strength of bonded PVC-U pipe connections was tested according to DIN EN ISO 9311-2. According to DIN EN 14814 the minimum requirement for the shear strength of the pipe connection at a test temperature of 23 C., 1 h after bonding is 0.4 MPa, 24 h after bonding 1.5 MPa and 480 h after bonding 7.0 MPa.

(2) A 75 mm long pipe section (material: PVC-U; 40 mm external diameter) was firstly bonded with an inventive 2-component (meth)acrylate adhesive to a fitting made of the same material over a length of 20 mm, and the shear strength of the connection was subsequently tested according to DIN EN ISO 9311-2. The inventively employed 2-component (meth)acrylate adhesive had the following frame formulation: a) methyl methacrylate in an amount of 30-60 wt %, b) hydroxyethyl methacrylate in an amount of 5-15 wt %, c) methacrylic acid in an amount of 1-5 wt %, d) components for improving the impact resistance in a total amount of 10 to 60 wt %, e) peroxide based-curing agents in an amount of 0.1 to 5 wt %, f) catalytic component for catalysing the curing reaction in an amount of 0.01 to 5 wt %, g) stabilizer in a total amount of 0.1 to 15 wt %, h) thickener in an amount of 0.5-20 wt %,
wherein each wt % indication is relative to the total composition.

(3) The shear strength of the connection determined according to DIN EN 14814 at a test temperature of 23 C., 1 h after bonding was 5.0 MPa, 24 h after bonding 16 MPa and 480 h after bonding 20.0 MPa. The final strength value can be taken as the 480 h value. Consequently, the invention already after 24 h enables a strength that is more than double that required by DIN EN 14814. Already after lh the connection exhibits a very high strength that is a multiple of the 24 h requirement of DIN EN 14814.

(4) In comparison, the same experiment was repeated, wherein this time a conventional solvent-based adhesive for PVC-U pipes was employed instead of the inventive 2-component (meth)acrylate adhesive. The shear strength of the bonded connection determined according to DIN EN 9311-2 1 h after bonding was 0.8 MPa, 24 h after bonding 2.5 MPa and 480 h after bonding 13 MPa. The bonding technology according to the invention is consequently clearly far superior in all respects to that based on the conventional solvent-based adhesive in regard to the obtained strength of the connection as well as the speed of the bonding effect.