Composition for synthetic stone

1. A composition for synthetic stone comprising:—

a. 3 to 25 wt % acrylic resin, the acrylic resin comprising:—

i. >50 up to 95 wt % methyl methacrylate (MMA) and methyl methacrylate (MMA) monomer residues,

ii. 4 to 40 wt % higher boiling point mono(alk)acrylate monomer,

iii. optionally, 0 to 10 wt % other acrylate or vinyl comonomer residues, and

iv. a crosslinking agent;

b. 70 to 95 wt % filler; and

c. optionally, a coupling agent;

wherein the MMA residues of component (axi) are present in the acrylic resin in the form of a MMA residue containing (co)polymer, comprising at least 80% residues of MMA by weight of the (co)polymer.

2. A kit of parts for forming synthetic stone, the kit of parts comprising:

an acrylic resin part comprising an acrylic resin according to acrylic resin (a) as defined in claim 1 , optionally further comprising coupling agent (c) as defined in claim 1 ; and

a filler part comprising a filler according to filler (b) as defined in claim 1 , wherein the MMA residues of component (a)(i) are present in the acrylic resin in the form of a MMA residue containing (co)polymer, comprising at least 80% residues of MMA by % weight of the (co)polymer.

3. The composition according to claim 1 , wherein the acrylic resin is present in an amount of between 4 and 20% by weight of the composition.

4. The composition according to claim 1 , wherein the filler is present at between 75 and 95 wt % by weight of the composition.

5. The composition according to claim 1 , wherein the MMA and/or MMA residues of component (a)(i) is present in the acrylic resin in an amount of between 55 and 95% by weight of the acrylic resin.

6. The composition according to claim 1 , wherein the MMA monomer component of (a)(i) is present in an amount of between 20 and 75% by weight of the acrylic resin.

7. The composition according to claim 1 , wherein the MMA residue component of (a)(i) is present in an amount of between 20 and 75% by weight of the acrylic resin.

8. The composition according to claim 1 , wherein the MMA residues of component (a)(i) are present in the acrylic resin in the form of a MMA residue containing (co)polymer, the MMA residue containing (co)polymer comprises at least 70% residues of MMA by weight of the (co)polymer.

9. The composition according to claim 8 , wherein the MMA residue containing (co)polymer is PMMA homopolymer.

10. The composition according to claim 1 , wherein a higher boiling point mono(alk)acrylate monomer, component (a)(ii), is present in an amount of between 5 and 40% by weight of the acrylic resin.

11. The composition according to claim 1 , wherein component (a)(ii) is selected from monomers having a higher boiling point than 101° C. at standard atmospheric conditions.

12. The composition according to claim 1 , wherein component (a)(ii) is selected from the monomer(s) (C 3 -C 12 )alkyl acrylate and/or (C 2 -C 12 )alkyl (C 1 -C 8 alk)acrylate.

13. The composition according to claim 1 , wherein the monomer(s) of component (a)(ii) are selected from one or more of the group consisting of ethyl methacrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, cyclohexyl (meth)acrylate and isobornyl(meth)acrylate including all skeletal isomeric forms such as n-, sec-, tert-, and/or iso-forms.

14. The composition according to claim 1 , wherein component (a)(ii) is formed of two or more higher boiling point mono(alk)acrylate monomers.

15. The composition according to claim 1 , wherein the crosslinking agent (a)(iv) is present in an amount of between 0.01 and 10% by weight of the acrylic resin.

16. The composition according to claim 1 , wherein the filler comprises a natural aggregate.

17. The composition according to claim 1 , wherein filler (b) comprises between 0.01 and 5% of pigment by weight of the composition.

18. The composition according to claim 1 , wherein the average size d50 of the filler (b) particles is <50 mm.

19. The composition according to claim 1 , wherein filler component (b) comprises a coarse filler fraction having an average particle size within the range 0.01 mm to 100 mm.

20. The composition according to claim 19 , wherein filler component (b) comprises a fine filler fraction with an average particle size that is smaller than the average particle size of the coarse filler fraction(s).

21. The composition according to claim 20 , wherein the fine filler fraction is present in filler (b) in an amount of between 0 and 40% by weight of the filler component.

22. The composition according to claim 19 , wherein the coarse filler fraction is present in an amount of between 60 and 100% by weight of the filler component.

23. The composition according to claim 1 , further comprising coupling agent, component (c).

24. The composition according to claim 1 , further comprising an initiator system, component (d).

25. The composition according to claim 24 , wherein the initiator system comprises at least a first initiator that has a half-life of up to one hour at below 80° C.

26. The composition according to claim 25 , wherein the initiator system comprises a mixture of two or more initiators.

27. The composition according to claim 24 , wherein initiator system (d) comprises one or more initiators selected from the group consisting of di-(t-butyl-cyclohexyl)peroxydicarbonate, azo-di-isobutyronitrile, dilauroyl peroxide, dibenzoyl peroxide, 2,2′-azodi(2-methylbutryonitrile) and/or Dicetylperoxydicarbonate.

28. A kit of parts for forming synthetic stone, the kit comprising:

an acrylic resin part comprising an acrylic resin according to acrylic resin (a) as defined in claim 1 , optionally further comprising coupling agent (c) as defined in claim 1 ,

a filler part comprising a filler according to filler (b) as defined in claim 1 ; and

an initiator part comprising an initiator system according to initiator system (d) as defined in claim 1 , wherein the MMA residues of component (a)(i) are present in the acrylic resin in the form of a MMA residue containing (co)polymer, comprising at least 80% residues of MMA by weight of the (co)polymer.

29. A method of manufacturing synthetic stone comprising the following steps:

a. mixing an acrylic resin according to acrylic resin (a) as defined in claim 1 , a filler according to filler (b) as defined in claim 1 , and optionally a coupling agent (c) as defined in claim 1 and optionally an initiator system (d) as defined in claim 1 ;

b. adding the mixture to a mould and substantially deaerating the mixture;

c. curing the mixture by heating; and

d. optionally polishing the cured mixture.

30. A method of manufacturing synthetic stone comprising the following steps:

a. mixing an acrylic resin according to acrylic resin (a) as defined in claim 1 , a filler according to filler (b) as defined in claim 1 , and optionally a coupling agent (c) as defined in claim 1 and optionally an initiator system (d) as defined in claim 1 ;

b. substantially deaerating the mixture,

c. adding the mixture to a press;

d. curing the mixture by heating; and

e. optionally polishing the cured mixture.

31. A method according to claim 29 wherein the MMA residue component of (a)(i) may be present, when initially mixed with (b) in step a., in an amount of at least 20% by weight of the acrylic resin.

32. A synthetic stone comprising:—

(a) 3 to 25 wt % acrylic resin, the acrylic resin comprising:—

i. >50 up to 95 wt % methyl methacrylate monomer residues of the MMA and MMA residues as defined in claim 1 ,

ii. 4 to 40 wt % higher boiling point mono(alk)acrylate monomer residues of the higher boiling point mono(alk)acrylate monomer as defined in claim 1 ,

iii. optionally, 0 to 10 wt % other acrylate or vinyl comonomer residues of acrylate or vinyl comonomers as defined in claim 1 , and

iv. crosslinking agent residues of crosslinking agents as defined in claim 1 ;

(b) 70 to 95 wt % filler as defined in claim 1 ; and

optionally, coupling agent residues of coupling agents as defined in claim 1 .