HYDROPONICS GROWING MEDIUM

Abstract

A hydroponics growing medium comprising mineral fibres and an organic binder, the growing medium has a Weathered Interlaminar Strength of at least 4 kilopascals and a phenol content of less than or equal to 0.01% by weight.

Claims

1. A hydroponics growing medium comprising mineral fibres and an organic binder, the growing medium having a Weathered Interlaminar Strength of at least 4 kilopascals and a phenol content of less than or equal to 0.01% by weight.

2. A hydroponics growing medium in accordance with claim 1, in which the Weathered Interlaminar Strength is at least 5 kilopascals.

3. A hydroponics growing medium in accordance with claim 1, in which the phenol content is less than 0.005 by weight, preferably less than 0.001% by weight.

4. A hydroponics growing medium in accordance with claim 1, in which the binder is substantially phenol free.

5. A hydroponics growing medium in accordance with claim 1, in which the binder content is in the range 2 to 10% by weight.

6. A hydroponics growing medium in accordance with claim 1, in which the binder content is greater than 4% by weight.

7. A hydroponics growing medium in accordance with claim 1, in which the binder is based on a reducing sugar.

8. A hydroponics growing medium in accordance with claim 1, in which the binder comprises at least one Maillard reaction product.

9. A hydroponics growing medium in accordance with claim 1, in which the binder is based on reaction products obtained by curing an aqueous solution comprising citric acid, ammonia and dextrose.

10. A hydroponics growing medium in accordance with claim 1, in which the binder is derived essentially from natural and/or sustainable raw materials.

11. A hydroponics growing medium comprising mineral fibres and an organic binder, the growing medium having a Weathered Interlaminar Strength of at least 4 kilopascals and the binder being derived essentially from natural and/or sustainable raw materials.

12. A plant grown in a hydroponics growing medium according to proceeding claim 1.

13. Use of a mineral fibre product comprising mineral fibres and an organic binder and having a Weathered Interlaminar Strength of at least 75 g/g and a phenol content of less than or equal to 0.01% as a hydroponics growing medium.

Description

[0033] A non-limiting example of the invention is described below.

[0034] An aqueous binder was prepared by mixing together:

TABLE-US-00001 Approximate % by weight Powdered dextrose monohydrate 29.8% Powdered anhydrous citric acid 5.3% 28% aqueous ammonia 6.0% Silane A-1100 1.0% Surfactant 6.2% Water 52.5%

[0035] This phenol free binder was used in the manufacture of a growing medium of rock wool on a standard rock wool manufacturing line, the binder being sprayed onto the fibres just after fiberising and the coated fibres being collected, assembled in to a mat, compressed and cured in the usual way.

[0036] The phenol free growing medium had: [0037] a binder content of about 5% by weight as determined by loss on ignition [0038] a thickness of about 65 mm [0039] a density of about 75 kg/m.sup.3

[0040] Desired characteristics and results achieved are set out in Table 1:

TABLE-US-00002 TABLE 1 Accep- More Most tance Pre- Pre- pre- Result Units limit ferred ferred ferred achieved Weathered Kilopascals 4 5 7.5 10 9.2 Interlaminar strength

Testing of Weathered Interlaminar Strength:

[0041] The test is carried out on mineral fibre mats which have been subjected to the following accelerated weathering procedure: five samples to be tested are placed in a preheated autoclave and conditioned on a wire mesh shelf away from the bottom of the chamber under wet steam at 35 kN/m.sup.2 for one hour. They are then removed, dried in an oven at 100 C. for five minutes and tested immediately for interlaminar strength.

[0042] The interlaminar strength is the tensile strength of the mineral fibre material in the direction substantially perpendicular to the principle plane in which the fibres have been deposited or are orientated. It is determined in accordance with European Standard EN1607 of November 1996 (incorporated herein by reference) with the following details and/or variations: [0043] the thickness of the samples is the thickness as commercialised [0044] the dimensions of the faces secured to the tensile testing machine are preferably 100 mm150 mm; samples having these dimensions are cut from the hydroponics growing medium as commercialised. Smaller dimensions may be used if the hydroponics growing medium is only commercialised in smaller dimensions. [0045] The adhesive used to secure the samples to the testing apparatus is preferably a hot melt adhesive

[0046] The Interlaminar strength is calculated as the mean average of the tensile strength of the five samples tested.