WO2015014953A1

WO2015014953A1 - Sulphur cement products

Info

Publication number: WO2015014953A1
Application number: PCT/EP2014/066527
Authority: WO
Inventors: Guy Lode Magda Maria Verbist; Cornelis Pieter Hamelink; Edward Ross DIXON; Arianne Elisabeth HOMMES
Original assignee: Shell Internationale Research Maatschappij B.V.; Shell Oil Company
Priority date: 2013-08-01
Filing date: 2014-07-31
Publication date: 2015-02-05
Also published as: EA030417B1; EP3027577A1; EA201690313A1; EA030417B9

Abstract

A sulphur cement product comprising sulphur and the reaction product of particulate inorganic material and an oligomeric organosilane is disclosed.

Description

SULPHUR CEMENT PRODUCTS

Field of the Invention

The present invention provides a process for the preparation of sulphur cement products. The invention also provides sulphur cement products including sulphur cement, sulphur mortar and sulphur concrete. The

invention also provides modified sulphur that can be used in the preparation of sulphur cement products. The invention also provides modified particulate inorganic material that can be used in the preparation of sulphur cement products.

Background of the Invention

Elemental sulphur or modified sulphur can be used to bind aggregate and filler, thereby providing sulphur cement products such as sulphur mortar and sulphur concrete . Sulphur concrete can be used in a variety of pre-cast concrete applications such as marine defences, paving slabs, road barriers and retaining walls.

WO 2008 148804 discloses that polysulphide- containing organosilanes can be used as stabilising agents to prepare sulphur cement products having improved water uptake behaviour. The sulphur cement products additionally have advantageous mechanical properties.

Additional stabilising or coupling agents are disclosed in WO 2011 000837 and WO 2012 101127.

When used in sulphur cement production, many of the organosilane coupling agents known in the prior art produce ethanol or methanol as a byproduct . Methanol and ethanol are volatile organic compounds (VOCs) and it is desirable to limit the amount of VOCs that are released during the manufacture of sulphur cement products. The inventors have sought to provide a process for

manufacturing sulphur cement products wherein the generation of VOCs is reduced and wherein the sulphur cement product retains satisfactory water uptake

behaviour and mechanical properties.

Summary of the Invention

The present inventors have found that by using a different type of organosilane in a process for the preparation of sulphur cement products it is possible to have reduced VOC production but still produce sulphur cement products having satisfactory water uptake

behaviour and mechanical properties.

Accordingly, the invention provides a process for the preparation of a sulphur cement product comprising the steps of:

(a) admixing sulphur, particulate inorganic material and an oligomeric organosilane having one or more terminal groups of general formula (I)

(I)

wherein R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms, and

(b) solidifying the molten sulphur cement product. In a further aspect, the present invention provides a sulphur cement product comprising sulphur and the reaction product of particulate inorganic material and an oligomeric organosilane having one or more terminal groups of general formula (I)

(I)

wherein R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms

In a yet further aspect, the present invention provides modified sulphur comprising sulphur and an oligomeric organosilane having one or more terminal groups of general formula (I)

(I)

wherein R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms. The modified sulphur is suitably used in a process for the preparation of the sulphur cement products of the invention .

In a yet further aspect, the present invention provides modified particulate inorganic material which is the reaction product of particulate inorganic material and an oligomeric organosilane having one or more terminal groups of general formula (I)

(I) wherein R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms. The modified particulate inorganic material is suitably used in a process for the preparation of the sulphur cement products of the invention.

Detailed Description of the Invention

The term "sulphur cement product" refers to a composite comprising sulphur, filler and optionally aggregate. Fillers and aggregate are particulate

inorganic materials. Fillers have an average particle size in the range of from 0.1 μπι to 0.1 mm. Fine

aggregate has an average particle size in the range of from 0.1 to 5mm. Coarse aggregate has an average particle size in the range of from 5 to 40mm. Average particle sizes are based upon mean averages. Sulphur cement of the invention comprises sulphur and filler, but no aggregate. Sulphur mortar of the invention comprises sulphur, filler and fine aggregate, but does not comprise coarse

aggregate. Sulphur concrete of the invention comprises sulphur, filler, coarse aggregate and optionally fine aggregate .

The amounts of sulphur, filler and aggregate in the sulphur cement products of the invention can be chosen by the skilled person in view of the proposed application of the sulphur cement product. The skilled person will seek to ensure that sufficient sulphur is incorporated to bind the filler and aggregate, that sufficient filler and aggregate are incorporated to provide mechanical strength and that the balance of components provides a mixture with suitable workability for the proposed application. Sulphur cement preferably comprises from 25 to 80wt% sulphur and from 20 to 75wt% filler. Sulphur mortar preferably comprises from 5 to 40wt% sulphur, from 45 to 90wt% fine aggregate and from 1 to 10wt% filler; more preferably from 5 to 30wt% sulphur, from 55 to 75wt% fine aggregate and from 3 to 8wt% filler. Sulphur concrete preferably comprises from 5 to 40wt% sulphur, from 25 to

50wt% coarse aggregate, from 20 to 40wt% fine aggregate and from 1 to 10wt% filler; more preferably from 5 to 30wt% sulphur, from 30 to 40wt% coarse aggregate, from 25 to 35wt% fine aggregate and from 3 to 8wt% filler.

The particulate inorganic material may be any particulate inorganic material known to be suitable as sulphur cement filler or aggregate. Preferably, the particulate inorganic material has oxide or hydroxyl groups on its surface. Examples of suitable particulate inorganic materials are silica, fly ash, limestone, quartz, iron oxide, alumina, titania, carbon black, gypsum, talc or mica, sand, gravel, rock or metal- silicates. More preferably the particulate inorganic material is a silica or a silicate. Examples of such silica or silicates are quartz, sand and metal-silicates

(e.g. mica) .

In the process of the invention, sulphur,

particulate inorganic material and an oligomeric

organosilane having one or more terminal groups of general formula (I) are admixed.

(I)

R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms. The oligomeric organosilane is suitably prepared by a process wherein a silane of formula (II) is reacted with a polyhydrox -containing compound of formula (III) :

(ID (in) wherein X is a hydrolysable leaving group, preferably Ci-₆ alkoxy and most preferably ethoxy. In a particular embodiment, more than one silane may be used, e.g. two silanes may be used:

R^2a R^2b

I I

XO— Si-OX XO— Si-OX

I I OX OX

This will lead to an oligomeric organosilane with a mixture of R^2a and R^2b groups .

The organosilane is oligomeric in that it will have resulted from the reaction of a number of organosilane monomers . The structure of the oligomeric organosilane is preferably according to formula (IV) :

(IV)

wherein n is an integer. The oligomer will have at least two terminal groups. At least one of the terminal groups, possibly more, will be of formula (I) .

R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms. Preferably R¹ has from 2-16 carbon atoms, more preferably from 2-8 carbon atoms.

Preferred groups include 2-methylpropyl and l-methyl-3,3- dimethylpropyl . Preferably the carbon chain between the linked oxygen atoms is three carbon atoms long. R¹ is preferably not functionalised .

R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms. Preferably R² has from 2-24 carbon atoms, more preferably from 2-16 carbon atoms. R² is optionally functionalised with one or more groups chosen from thiol, thioester, alcohol, ester, carboxylic acid, carbonyl amine or amide groups . In a preferred embodiment, R² is functionalised with a thiol or

thioester group.

Suitable oligomeric organosilanes and methods for making them are disclosed in WO 2006 86375 and WO 2008 21308. Oligomeric organosilanes are available from

Momentive Performance Materials Inc. under the brand name

NXT* Z.

The sulphur cement products of the invention are suitably prepared by a process wherein all the components are admixed at a temperature at which the sulphur is molten, i.e. typically above 120°C, preferably in the range of from 120 to 150°C, more preferably in the range of from 125 to 140°C. The admixture is preferably poured into a mould. The sulphur cement product is then

solidified by cooling to a temperature at which the sulphur solidifies. After cooling, the sulphur cement product can be demoulded.

The amount of oligomeric organosilane that is admixed with the sulphur and the particulate inorganic material is preferably from 0.05 to lwt%, based upon the weight of the sulphur, preferably from 0.1 to 0.4wt%.

When less than 0.05wt% of oligomeric organosilane is used then the modification may provide insufficient

improvement in water uptake and mechanical properties. It is typically unnecessary to use in excess of lwt% of oligomeric organosilane because all of the possible improvement in water uptake and mechanical properties will have been achieved by using lwt%.

When the oligomeric organosilane is admixed with the inorganic particulate material, there is reaction of the terminal groups of the oligomeric organosilane with surface groups of the inorganic particulate material. During the process, compounds of formula HO-R¹-OH will be produced and such compounds tend to have boiling points that are sufficiently high that they are not considered to be VOCs.

In the process of the invention, a selection of the components may be supplied to the mixing step in the form of a pre-composition or masterbatch. In one embodiment, sulphur and the oligomeric organosilane may be supplied as modified sulphur. Therefore, in a further aspect, the present invention provides modified sulphur, comprising sulphur and an oligomeric organosilane having one or more terminal groups of general formula (I)

(I)

wherein R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms. The modified sulphur preferably comprises less than lwt% filler and less than lwt% aggregate; and most preferably comprises no filler and no aggregate. The modified sulphur preferably comprises from 0.01 to 20wt% of oligomeric organosilane, more preferably from 0.01 to 10wt%, most preferably from 0.01 to lwt%, wherein weight percentages are based upon the weight of the modified sulphur. The modified sulphur preferably comprises at least 80wt% sulphur. In one embodiment, the modified sulphur may comprise higher quantities of oligomeric organosilane, e.g. from 5 to 20wt%, and may also comprise higher quantities of filler, e.g. from 5 to 20wt%, wherein weight percentages are based upon the weight of the modified sulphur. In this embodiment, the modified sulphur is a "concentrated" modified sulphur and such a "concentrated" modified sulphur can be used in small quantities to provide significant amounts of oligomeric organosilane .

In another embodiment, particulate inorganic material and the oligomeric organosilane may be supplied as modified particulate inorganic material. Therefore, in a further aspect, the present invention provides modified particulate inorganic material which is the reaction product of particulate inorganic material and an

oligomeric organosilane having one or more terminal groups of general formula I)

(I)

wherein R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms. The modified particulate inorganic material is suitably prepared by combining particulate inorganic material with from 0.001 to 5wt% of oligomeric organosilane, more preferably from 0.01 to lwt%, most preferably from 0.01 to 0.1wt%, wherein weight percentages are based upon the weight of the particulate inorganic material. Sulphur cement products produced according to the invention can be used in a variety of applications .

Sulphur concrete may be used in pre-cast concrete applications such as marine defences, paving slabs, road barriers and retaining walls .

Examples

The invention is further illustrated by means of the following non-limiting examples.

Examples 1-6:

Sulphur mortar samples (Fly Ash/Normsand) were made using the following method:

Sulphur (25% (w/w)), pre-heated to approximately 65°C, and pre-heated sand (150°C, 60% (w/w)) were mixed at 140°C until a homogenous mixture was obtained. If appropriate, 0.06% (w/w) of bis (3- triethoxysilylpropyl) tetrasulphide (TESPT) was added to the mixture and continuously stirred for 5 minutes. The appropriate quantity of NXT Z 100 modifier (see Table 1) was then added and mixed in for another 5 minutes. Pre- heated Fly Ash (150°C, 15% (w/w)) was then added to the mixture and stirred for another 10 minutes. Finally the mixes were poured into pre-heated (150°C) 4 cm x 4 cm x 16 cm silicon moulds and allowed to cool to ambient temperature in a fume-hood. The mortars were allowed to cure for a minimum of 48 hours.

Table 1

NXT Z 100 is an oligomeric organosilane available from Momentive Performance Materials Inc. Three samples of the organosilane were used: sample [1] was a fresh bottle of the organosilane, sample [2] was a two-week-old bottle of the organosilane and sample [3] had been exposed to atmospheric conditions in a fume-hood

overnight. NXT Z 100 is prone to moisture uptake as indicated by 9.20% mass gain when exposed to atmospheric conditions overnight in a fume-hood.

During all experiments there were no detectable emissions of H₂S and S0₂ using handheld detectors (lower detection limit - 0.2 ppm) .

The durability of the sulphur mortars was determined by measuring flexural strength retention and water intrusion after two months submersion in water. Results are shown in Figures 1 and 2. The sulphur mortars prepared according to the process of the invention have better strength retention and water intrusion properties than a sulphur mortar that does not contain organosilane (comparative example 1) . They have similar, but slightly worse, strength retention and water intrusion properties than a sulphur mortar that comprises a TESPT organosilane (comparative example 2) .

Example 7 :

Sulphur mortar samples (Fly Ash/Normsand) were made using the following method:

Sulphur (25% (w/w) ) pre-heated to approximately 65°C, and pre-heated sand (150°C, 60% (w/w)) were mixed at 140°C until a homogenous mixture was obtained. The appropriate quantity of bis (3- triethoxysilylpropyl) tetrasulphide (TESPT) (0.06 wt%) or

NXT Z 100 modifier (0.02, 0.04, 0.06 or 0.12 wt%) was then added and mixed in for another 5 minutes. Pre-heated Fly Ash (150 °C, 15% (w/w)) was then added to the mixture and stirred for another 10 minutes. Finally, the mixes were poured into pre-heated (150 °C) 4 cm x 4 cm x 16 cm silicon moulds and allowed to cool to ambient temperature in a fume-hood. The mortars were allowed to cure for a minimum of 48 hours.

During all experiments there were no detectable emissions of H₂S and S0₂ using handheld detectors (lower detection limits - 1.6 ppm for H₂S and 2 ppm for S0₂) .

The durability of the sulphur mortars was determined by measuring water intrusion and flexural strength retention after one month submersion in water.

Samples containing NXT Z 100 in all tested

concentrations have considerably lower water intrusion and higher strength retention in comparison to a sample containing no modifier. Water intrusion and strength retention of all NXT samples are comparable to the sample containing 0.06 wt% TESPT.

Example 8 :

Sulphur mortar samples (Fly Ash/Normsand) were made using the following method: Sulphur (25% (w/w) ) pre-heated to approximately 65 °C and pre-heated sand (150 °C, 60% (w/w)) were mixed at 140 °C until a homogenous mixture was obtained. The appropriate quantity of TESPT (0.06 wt%) or NXT Z 100 modifier (0.02, 0.04, 0.06 or 0.12 wt%) was then added and mixed in for another 5 minutes. After this pre-heated Fly Ash (150 °C, 15% (w/w)) was added to the mixture and stirred for another 10 minutes. Finally the mixes were poured into pre-heated (150 °C) 4 cm x 4 cm x 16 cm silicon moulds and allowed to cool to ambient temperature in a fume-hood. The mortars were allowed to cure for a minimum of 48 hours.

During all experiments there were no detectable emissions of H₂S and S0₂ using handheld detectors (lower detection limits - 1.6ppm for H₂S and 2ppm for S0₂) .

The durability of the sulphur mortars was determined by measuring water intrusion and flexural strength retention after submersion in water for approximately eight months .

Samples containing 0.02 and 0.04 wt% NXT Z 100 perform similarly in terms of water intrusion to the sample containing 0.06 wt% TESPT. Also, their strength retention after almost 8 months storage in water is rather high (83.5% and 107.2% for samples containing 0.02 and 0.04wt% NXT Z 100, respectively).

Claims

C L A I M S

1. A process for the preparation of a sulphur cement product comprising the steps of:

(I)

(b) solidifying the molten sulphur cement product.

2. A process according to claim 1, wherein the amount of oligomeric organosilane that is admixed with the sulphur and the particulate inorganic material in step (a) is from 0.05 to lwt%, based upon the weight of the sulphur .

3. A sulphur cement product comprising sulphur and the reaction product of particulate inorganic material and an oligomeric organosilane having one or more terminal groups of general formula (I)

(I) wherein R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms

4. Modified sulphur comprising sulphur and an

oligomeric organosilane having one or more terminal groups of general formula (I)

(I)

wherein R¹ is a linear or branched hydrocarbyl group having from 2-24 carbon atoms and R² is a linear or branched hydrocarbyl group having from 2-40 carbon atoms.

5. Modified particulate inorganic material which is the reaction product of particulate inorganic material and an oligomeric organosilane having one or more terminal groups of general formula I)

(I)

6. A process according to claim 1 or claim 2, wherein in step (a) , modified sulphur according to claim 4 is admixed with particulate inorganic material .

7. A process according to claim 1 or claim 2, wherein in step (a) , modified particulate inorganic material according to claim 5 is admixed with sulphur.