Impregnation process for a fibrous substrate, a liquid monomer syrup for the impregnation process, its method of polymerization and structured article obtained thereof

1. An impregnation process for impregnating a fibrous substrate, wherein said fibrous substrate is made of long fibres having an aspect ratio of at least 1000, said fibers having a diameter between 0.005 micrometers and 100 micrometers, and said process comprises a step of impregnating said fibrous substrate with a liquid monomer syrup comprising:

a) a (meth)acrylic polymer,

b) at least one monomer (A) chosen from a (meth) acrylic monomer or a vinyl monomer or mixture thereof,

c) at least one initiator or initiating system for starting the polymerization of the (meth) acrylic monomer,

d) optionally another (meth) acrylic monomer (B)

wherein the at least one monomer (A) chosen from (meth) acrylic monomer or vinylic monomers has a boiling point of at least 115° C. at 1013 mbar and/or a vapour pressure of less than 25 mbar at 20° C. and

wherein the other (meth)acrylic monomer B has a boiling point less than 115° C. at 1013 mbar and/or a vapour pressure of more than 25 mbar at 20° C.,

and wherein said liquid monomer syrup has a dynamic viscosity of a value in the range from 10 mPa*s to 10000 mPa*s,

wherein monomer (A) is present at more than 50 wt % and (meth)acrylic monomer (B) presents less than 50 wt % of the total sum of monomers (A) and (B) present in the liquid monomer syrup, and wherein monomer (A) is selected from the group consisting of cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, heptyl methacrylate, n-octyl acrylate, 2-octyl acrylate, iso-octyl acrylate, 2-ethylhexyl methacrylate, butyl diglycol methacrylate, dicyclopentenyloxyethyl methacrylate, ethoxy ethyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, hydroxyl propyl methacrylate, styrene, alpha methyl styrene, ortho-, beta- or para-methyl styrene, tert-butyl styrene, nitro styrene, N-vinylpyrrolidone, and mixtures thereof.

2. The impregnation process according to claim 1 , wherein monomer (A) has vapour pressure of less than 10 mbar at 20° C.

3. The impregnation process according to claim 1 , wherein monomer (A) has boiling point of at least 135° C. at 1013 mbar.

4. The impregnation process according to claim 1 , wherein the monomer syrup comprises the (meth) acrylic monomer (B).

5. The impregnation process according to claim 4 , wherein the (meth)acrylic monomer (B) is chosen from alkyl acrylic monomers the alkyl group having from 1 to 4 carbons either linear or branched, methyl methacrylate and mixtures thereof.

6. The impregnation process according to claim 4 , wherein the (meth)acrylic monomer (B) is chosen from methyl methacrylate, methyl acrylate, ethyl acrylate and mixtures thereof.

7. The impregnation process according to claim 1 , wherein the (meth)acrylic polymer is a homo- or copolymer of methyl methacrylate (MMA) or a mixture thereof.

8. The impregnation process according to claim 7 , wherein the copolymer of methyl methacrylate (MMA) comprises at least 70% by weight of methyl methacrylate (MMA).

9. The impregnation process according to claim 1 , wherein the copolymer of methyl methacrylate (MMA) comprises from 70% to 99.7% by weight of methyl methacrylate and from 0.3 to 30% by weight of at least one monomer having at least one ethylenic unsaturation that can copolymerize with methyl methacrylate.

10. The impregnation process according to claim 9 , wherein the comonomer is chosen from methyl acrylate or ethyl acrylate and a mixture thereof.

11. The impregnation process according to claim 1 , wherein said initiator or initiating system for starting the polymerization of monomer (A) and the (meth) acrylic monomer (B) is generating radicals.

12. The impregnation process according to claim 1 , wherein said initiator or initiating system for starting the polymerization of monomer (A) and the (meth) acrylic monomer (B) is chosen from diacyl peroxides, peroxy esters, dialkyl peroxides, peroxyacetals, hydroperoxides, azo compounds and mixtures thereof.

13. The impregnation process according to claim 1 , wherein the (meth)acrylic polymer in the liquid monomer syrup present at least 5% by weight of total weight of compounds a)+b)+c)+d) of the liquid monomer syrup.

14. The impregnation process according to claim 1 , wherein the (meth)acrylic polymer in the liquid (meth) acrylic syrup present at most 60% by weight of total weight of compounds a)+b)+c)+d) of the liquid monomer syrup.

15. The impregnation process according to claim 1 , wherein the monomer (A) and the monomer (B) in the liquid monomer syrup present at least 30% by weight of total weight of compounds a)+b)+c)+d) of the liquid monomer syrup.

16. The impregnation process according to claim 1 , wherein the liquid monomer syrup comprises:

a) from 5 wt % to 59.99 wt % (meth)acrylic polymer,

b) from 30 wt % to 89.99 wt % sum of monomer (A) and monomer (B),

c) from 0.01 wt % to 5 wt % one initiator or initiating system for starting the polymerization of the monomer or monomers,

d) from 0 wt % to 1 wt % activator,

e) from 0 wt % to 60 wt % filler, and

f) from 0 wt to 20 wt % additives.

17. A manufacturing process for manufacturing mechanical or structured parts or articles comprising following steps:

a) impregnating a fibrous substrate with a liquid monomer syrup according to claim 1 , and

b) polymerising the liquid monomer syrup impregnating said fibrous substrate.

18. The process according to claim 17 , wherein the impregnation of the fibrous substrate in step a) is made in a mold.

19. The process according to claim 17 , wherein in step a) and step b) are made in the same mold.

20. The process according to claim 17 , wherein the process is chosen from pultrusion, hand lay up, spray-up, resin transfer molding and infusion.

21. The process according to claim 17 wherein the temperature of the polymerization is step b) is below 120° C.