GB2059430A - A hot melt thermo-plastic road- marking compound - Google Patents

Abstract

The invention provides a hot melt thermoplastic road-marking composition which consists of the following components: (1) 7 to 38 weight percent of a synthetic hard resin, (2) 1 to 10 weight percent of a plasticizer, (3) 0 to 10 weight percent of an elastomer, (4) 1 to 15 weight percent of pigments, (5) 0 to 35 weight percent of glass beads, (6) 10 to 50 weight percent of a mineral aggregate, (7) 10 to 50 weight percent of an extender and (8) 0 to 5 weight percent of a stabilizer. The compositions are particularly readily applied and of high durability.

Description

SPECIFICATION A hot melt thermoplastic road-marking compound The invention relates to a novel composition suitable for use in road-surface marking, and in addition provides a method whereby road surfaces may be marked using the novel composition.

A composition to be used in road marking must have sufficient durability to enable it to withstand weathering and the constant passage of traffic over it, and be capable of good adhesion to the road surface so as not to be loosened and chipped away in use. In addition it must be able to provide clear distinct lines in white, yellow or any other desired colour. It is advantageous to apply the marking composition to the road in the form of a hot melt from a suitable apparatus; it is particularly convenient to use in this connection a screed type applicator (also known as an extrusion type applicator). By careful selection of components, we have developed novel compositions capable of meeting the above criteria, and which have advantages over compositions previously used.In particular, the novel compositions of the invention have a lower viscosity in the molten state than the compositions of the prior art, and are thus more easily applied to the road surface, and may be applied in a thinner coat, but without comparative. loss in durability. For example, conventional hot applied road marking materials as specified in British Standard BS3262: 1976 must be applied in a layer at least 3 mm in thickness, whereas the compositions of the invention may be applied in thin layers of less than 1.5 mm thickness without substantial loss in durability.

Accordingly this invention provides, in one aspect, a composition for use in marking the surfaces of roads and which is applied thereto in the form of a hot melt, which composition consists of the following ingredients: (1) from 7 to 38 percent by weight of a synthetic hard resin binder component; (2) from 1 to 10 percent by weight of a plasticiser, (3) from 0 to 10 percent by weight of an elastomer, (4) from 1 to 1 5 percent by weight of a pigment, (5) from 0 to 35 percent by weight of glass beads, (6) from 10 to 50 percent by weight of a mineral aggregate, (7) from 10 to 50 percent by weight of an extender and (8) from 0 to 50 percent by weight of a stabilizer.

As the binder component (1), one or more kinds of hard-resin components such as rosin modified alkyd resin, rosin modified maleic resin, styrol resin, saturated polyester resin, petroleum resin, cumaron resin or terpene resin can be used. The plasticiser component (2) may be composed of one or more compounds commonly used as plasticisers such as phalate plasticisers, (for example dibutyl phthalate and dioctyl phthalate), phosphate ester plasticisers such as TCP, low molecular weight hydrocarbon resins, mineral oils, vegetable oils, paraffin waxes, and low molecular weight polyolefin wax, or mixtures of such plasticisers. The elastomer (3) may be a rubber such as butyl rubber, an elastomeric polyester, a polyamide or an ethylene vinyl acetate copolymer.As the pigment (4), a white pigment such as titanium dioxide or zinc oxide, yellow pigments such as chrome yellow, titanium yellow or cadmium yellow, and/or phthalocyanine green and phthalocyanine blue, which are of high heat resisting properties, can be used. Suitable mineral aggregates (6) include granular calcite, silica sand and glass chips. Examples of suitable extenders (7) are limestone powder, precipitated calcium carbonate, white silica powder, kaoline and barium sulphate powder. As stabilizers (8), anti-oxidants, ultraviolet absorbers, anti precipitators and dispersoids may be included.The binder components listed above use hard, brittle materials which would be unsuitable for use as constituents of a road marking compositions without the addition of the plasticisers and elastomers which give the compositions the required fluidity when molten and durability after setting. The hard resin binders are particularly advantageous since they can be made very clear and transparent so that the colours of the pigments and the reflectance of the glass beads (when these are used) are not obscured. The particularly preferred resins used as binders are or or C2C9 C5/C9 hydrocarbon hard resins as described below.

A suitable C5 hydrocarbon hard resin may be produced by polymerisation of 5-carbon fractions such as isoprene, piperylene or cyclopentadiene obtained from the cracking of petroleum naphtha.

Examples of possible structural formulae for such resins are given in formulae I and II:

wherein n is an integer. Similarly, a C9 hydrocarbon hard resin may be produced by polymeristion of 9carbon fractions such as vinyl toluene or indene obtained by cracking of petroleum naphtha, and examples of structural formulae for such resins are given in formulae III and IV:

wherein n is an integer. A suitable Cs/Cg hydrocarbon hard resin may be produced by polymerisation of a mixture of the aforementioned 5-carbon and 9-carbon fractions.

The plasticisers are included to enable the road marking composition to have the increased fiuidity mentioned above allowing it to be applied in a thinner coat, whilst the elastomer ensures that the composition has the durability necessary for it to function satisfactorily in practice. The remaining components (aggregates, pigments, extenders and glass beads) perform similar functions to the corresponding components in conventional compositions. Stabilizers are included to ensure that the compositions have resistance to deterioration in service.

It is preferred to apply the compositionat a temperature of between 1 80-2000C. By using careful application procedures, it is possible to produce surfaces which are uniform in texture and thickness and appreciably free from blisters and streaks. The compositions according to the invention may be applied to the road surface in the form of a hot melt, and for this purpose it is convenient to use a screed type applicator (also known as an extrusion type applicator) or a spray applicator. They may be used to make traffic lines and symbols such as the centre, side lane and shoulder lines of roads, pedestrian crossings, direction lines at intersections and arrow and word markings.

In a particular preferred embodiment of the method of the invention, the composition is applied to the road surface in the molten state by means of a screed type applicator, and glass beads additional to those which may be incorporated in the composition are applied to the surface of the molten composition by a suitable dispenser, simultaneously with, or just after, the layer of the molten composition on the road surface. The additional beads (so-called drop-on beads) then become attached to the surface of the material as it cools and solidifies and increases its overall reflectancy. It is preferred to apply the drop-in beads at the rate of between 280-500 g per square metre of the marked surface area.

When a hand applicator is used to apply the compositions, the following procedures may be adopted:1) The road surface to be marked is cleaned by sweeping. Any damp spot and oil or grease stain is burned off with a gas burner.

2) Pre-marking is affected with a pre-marking rope or chalk.

3) The adhesive primer, which is diluted with a solvent, is sprayed or roller-coated over the area of road surface to be marked. The solvent in the adhesive primer normally evaporates in 3-5 minutes and the surface looks dull.

4) The thermoplastic marking material of the invention is heated and fused in the liquid state in a melting kettle and is transferred to a hand applicator such as that shown in Fig. 1 of the accompanying drawings.

5) The hand applicator is moved forward immediately after opening the slit gate of the marking shoe, and then additional glass beads are dispensed on the top of the marking surface automatically to produce a reflective road marking as shown diagrammatically in Fig. 4 of the accompanying drawings.

6) Traffic may be allowed over the marked areas 3 minutes after laying.

There are several types of spraying machines, but one standard machine having a spraying system is shown in Fig. 6 of the accompanying drawings.

The following Examples are given to illustrate, but not limit, the invention: EXAMPLE 1 The white road-marking compound blended uniformly with a mixer in the following formula has shown satisfactory performance as given in Table 1: rosin modified maleic resin 15 wt % DBP (dibutyl phthalate) 3 titanium dioxide 10 granular calcite 25 limestone powder 31 EVA (Ethylene vinyl acetate copolymer) 1 glass beads (average particle size 0.4 mm) 15 " TABLE 1

Characteristic of testing Result of testing specific gravity 2.1 softening point ( C) 104 non pick-up time less than 3 min.

whiteness 84 yellowness 0.02 compressive strength (kg/cm) 340 abrasive resistance (mg) 80 resistance to accelerated weathering good water absorption (%) less than 0.01 resistance to alkali good EXAMPLE 2 The white road-marking compound blended uniformly with a mixer in the following formula has shown satisfactory performance as given in Table 2:: C5 petroleum resin as described above 18 wt% DOP (diocyl phthalate) 1 EVA (ethylene vinyl acetate copolymer) 1 titanium dioxide 12 granular calcite 22 glass beads 20 limestone powder 26 TABLE 2

Characteristic of testing Result of testing specific gravity 2.2 softening point (O-C) 100 non pick-up time less than 3 min.

whiteness 86 yellowness 0.02 compressive strength (kg/cm) 380 abrasive resistance (mg) 72 resistance to accelerated weathering good water absorption (%) less than 0.01 resistance to alkali good EXAMPLE 3 The yellow road-marking compound blended uniformly with a mixer in the following formula has shown satisfactory performance as given in Table 3: : C5 and C9 hydrocarbon resin as described above 16 wt % low moleculerpolybutadiene 3 chrome yellow 4.5 EVA 1 silica sand 46 chelex as anti-oxidant 0.5 silica powder 29 TABLE 3

Characteristic of testing Result of testing specific gravity 2.0 softening point (OC) 108 non pick-up time less than 3 min.

whiteness yellowness compressive strength (kg/cm2) 320 abrasive resistance (mg) 86 resistance to accelerated weathering good water absorption (O/o) less than 0.01 resistance to alkali good

Claims (14)

1. A hot melt thermoplastic road-marking composition which consists of the following components: (1) 7 to 38 weight percent of a synthetic hard resin, (2) 1 to 10 weight percent of a plasticizer, (3) 0 to 10 weight percent of a elastomer, (4)1 to 1 5 weight percent of pigments, (5) 0 to 35 weight percent of glass beads, (6) 10 to 50 weight percent of a mineral aggregate, (7) 10 to 50 weight percent cf an extender and (8) 0 to 5 weight percent of a stabilizer.

2. A composition as claimed in claim 1 wherein the synthetic hard resin is a rosin modified alkyd resin, a rosin modified maleic resin, a saturated polyester resin, a petroleum resin, a cumaron resin or a terpene resin.

3. A composition as claimed in either of the preceding claims wherein the synthetic hard resin is a C5 hydrocarbon hard resin, a Cg hydrocarbon hard resin or a C5/Cg hydrocarbon hard resin, those terms denoting resins obtained from polymerisation of 5-carbon, 9-carbon and mixtures of 5- and 9-carbon fractions respectively, obtained from the cracking of petroleum naphtha.

4. A composition as claimed in claim 3 wherein the C5 hydrocarbon hard resin is represented by either of formulae I or II:

wherein n is an integer.

5. A composition as claimed in claim 3 wherein the C9 hydrocarbon hard resin is represented by either of formulae Ill or IV:

wherein N is an integer.

6. A composition as claimed in either of the preceding claims wherein the plasticiser is a phthalate plasticiser, a phosphate ester plasticiser, a low molecular weight hydrocarbon resin, a mineral-or vegetable oil, a paraffin wax or a low molecular weight polyolefin wax, or a mixture thereof.

7. A composition as claimed in either of claims 1 and 2 wherein the plasticiser is dibutyl and/or dioctyl phthalate.

8. A composition as claimed in any of the preceding claims wherein the elastomer is a rubber, an elastomeric polyester, a polyamide or an ethylene vinyl acetate copolymer.

9. A composition as claimed in any of the preceding claims wherein the pigment is titanium dioxide, zinc oxide, chrome yellow, titanium yellow, cadmium yellwo, phthalocyanine green or phthalocyanine blue.

10. A composition as claimed in any of the preceding claims wherein the mineral aggregate consists of granular calcite silica sand or glass chips.

11. A composition as claimed in any of the preceding claims wherein the extender is limestone powder, precipitated calcium carbonate, white silica powder, kaoline or barium sulphate powder.

12. A composition as claimed in any of the preceding claims wherein the stabilizer is an antioxidant, an ultraviolet absorber, an anti-precipitator or a dispersoid, or a mixture thereof.

13. A method of marking a road surface in which a composition as claimed in any of the preceding claims is applied to the surface in the form of a hot melt using a screed type applicator.

14. A method as claimed in claim 1 3 wherein the temperature of the molten material is in the range of 180--2000C.

1 5. A method as claimed in claim 13 wherein glass beads additional to those which mav be ,incorporated in the composition are applied to the surface of the molten composition by a suitable dispenser, simultaneously with, or just after, the laying of the molten material on the road surface.

1 6. A method as claimed in claim 1 5 wherein the additional glass beads are applied at the rate of between 280-500 g per square metre of the marked surface area.

1 7. A road marking composition as claimed in claim 1 substantially as herein described.

1 8. A road marking composition as claimed in claim 1 substantially as herein described in any of Examples 1-3.