Additive manufacturing composition
An additive manufacturing composition for powder bed processes is described. The composition includes at least a first type of impact modified polymer beads. The polymer beads include a) an acrylic or vinyl (co)polymer matrix, and b) an impact modifier in which at least 85% w/w of the first type of impact modified polymer beads have a particle size of between ≥20 μm and ≤200 μm and/or on average the impact modified polymer beads have greater than 5% w/w impact modifier. Also disclosed is an additive manufacturing process for a production of a three dimensional product comprising fused impact modified polymer particles. The use of a composition in additive manufacturing, an additive manufacturing cartridge or replacement hopper and a process for the production of impact modified polymer beads by a suspension polymerization process is also disclosed.
1. An additive manufacturing composition for powder bed processes comprising at least a first type of impact modified polymer beads formed by suspension polymerization, wherein the first type of impact modified polymer beads comprises
a) an acrylic or vinyl (co)polymer matrix, and
b) an impact modifier;
wherein at least 85% w/w of the first type of impact modified polymer beads have a particle size of between ≥20 μm and ≤125 μm; and
wherein in component a) the (co)polymer matrix comprises 70-100% alkyl (alk)acrylate and/or styrene residues by weight of the (co)polymer matrix, and 0-30% by weight of one or more other vinyl monomer residues, wherein, the impact modifier is selected from one or more of (co)polymers, oligomers or reactive oligomers having a Mw of between 1000 and 10000, or core-shell impact modifiers.
2. The composition according to claim 1 , wherein a d50 particle size of the first type of impact modified polymer beads is ≥40 μm and ≤90 μm.
3. The composition according to claim 1 , wherein the impact modifier is selected from the group consisting of acrylic, styrene, silicone, nitrile rubber, isoprene, butadiene, isobutylene and aliphatic polyurethane, polyether oligomer and polyester oligomer modifiers.
4. The composition according to claim 1 , wherein an amount of impact modifier in the first type of impact modified polymer bead is up to 60 wt %.
5. The composition according to claim 1 , further comprising a flow modifier and/or an antistatic agent.
6. The composition according to claim 1 , wherein the impact modifier is crosslinked, or otherwise substantially insoluble or sparingly soluble in the (co)monomers used to form the (co)polymer matrix of part a) or is an oligomer or reactive oligomer with a molecular weight (Mw)≤10000.
7. The composition according to claim 1 , wherein the impact modifier forms elastomeric regions in the first type of impact modified polymer bead and the acrylic or vinyl (co)polymer matrix forms a continuous phase in the first type of impact modified polymer bead.
8. The composition according to claim 1 , wherein the composition includes one or more further types of impact modified polymer beads.
9. The composition according to claim 8 , wherein at least 85% w/w of the one or more further types of impact modified polymer beads have a particle size of between ≥20 μm and ≤200 μm.
10. The composition according to claim 1 , wherein the composition further includes non-impact modified polymer beads.
11. The composition according to claim 10 , wherein at least 85% w/w of the said one or more non-impact modified polymer beads have a particle size of between ≥20 μm and ≤200 μm.
12. An additive manufacturing cartridge or replacement hopper comprising a composition according to claim 1 .
13. An additive manufacturing composition comprising at least a first type of impact modified polymer beads formed by suspension polymerization, wherein the first type of impact modified polymer beads comprises
a) an acrylic or vinyl (co)polymer matrix, and
b) an impact modifier;
wherein at least 85% w/w of the first type of impact modified polymer beads has a particle size of between ≥20 μm and ≤125 μm; and
wherein on average the first type of impact modified polymer beads comprises greater than 5% w/w impact modifier, wherein, the impact modifier is selected from one or more of (co)polymers, oligomers or reactive oligomers having a Mw of between 1000 and 10000, or core-shell impact modifiers.
14. A process for the production of impact modified polymer beads by a suspension polymerisation process comprising the steps of:
a. providing a suspension comprising;
i. impact modifier,
ii. acrylic or vinyl (co)monomer(s),
iii. water, and
iv. a water soluble polymeric dispersing agent such that i and ii form a discontinuous organic phase and iii and iv form a continuous aqueous phase of the suspension;
b. suspension polymerising the discontinuous organic phase of a; and
c. optionally, extracting the impact modified polymer beads,
d. wherein a viscosity of monomer droplets in the discontinuous organic phase is such that at least 90% w/w thereof have a particle size of between ≥20 μm and ≤200 μm,
wherein the impact modified polymer beads comprise:
a) an acrylic or vinyl (co)polymer matrix, and
b) an impact modifier;
wherein at least 85% w/w of the impact modified polymer beads have a particle size of between ≥20 μm and ≤125 μm and the impact modifier is selected from one or more of (co)polymers, oligomers or reactive oligomers having a Mw of between 1000 and 10000, or core-shell impact modifiers.
15. The process according to claim 14 , wherein the impact modifier is non-alkali treated.
16. The process according to claim 14 , wherein a Brookfield viscosity of the discontinuous organic phase prior to polymerization is less than 4,000 centipoise.