ISO 16862:2003 塗料とワニス—たるみ耐性の評価 | ページ 2

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 16862 was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 9, General test methods for paints and varnishes.

Introduction

When a wet coat of paint is applied to an inclined surface, the coat will flow down the surface under its own weight with cohesive forces opposing this flow. The balance of rheological and gravitational forces will allow a certain wet-film thickness to be applied without this unwanted flow becoming objectionable. Flow down an inclined surface is normally unstable, particularly if the coat is of uneven thickness, and it is this instability that leads to unsightly sags and tears. For a vertical surface, the gravitational force per unit area of surface, i.e. the stress, is given by h × d × g, where h is the film thickness in micrometres, d is the density of the coat of paint in kilograms per cubic metre and g is the gravitational constant in metres per second squared. The cohesive force per unit area of the surface is given by V × dv/dl, where V is the Newtonian viscosity in pascal seconds and dv/dl is the shear rate in reciprocal seconds. This International Standard describes two methods for determining the maximum wet-film thickness of a coating which can be applied to a vertical surface without giving rise to sagging or similar phenomena. The first method is carried out on a small scale using sag index applicators and the second is a larger-scale, practical test.

1 Scope

This International Standard describes test methods for evaluating the sag resistance (resistance to sagging) of paints, varnishes and similar coating materials (coatings) when applied to a substrate and held in a vertical position.

Evaluation of the sag resistance can be carried out after the coating has been applied as follows:

• a) using a sag index applicator on a horizontally placed test panel which is afterwards put into a vertical position,or
• b) using a spray gun for application on a substrate in a vertical position.

This International Standard is applicable to liquid coatings only.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

Bibliography