All posts tagged injection moulding

TPU-Silicone TPVs

Patent Title: THERMOPLASTIC POLYURETHANE COMPOSITE MATERIAL COMPOSITION, THERMOPLASTIC POLYURETHANE COMPOSITE MATERIAL AND MANUFACTURING METHOD THEREOF, SHOE MATERIAL AND WEARABLE APPARATUS

Number/Link: US2017 /0015825

Applicant/Assignee: Evermore Chem. Ind.

Publication date: 19-jan-2017

“Gist”: A blend of TPU and unsaturated silicone gum is dynamically vulcanized

Why it is interesting: A thermoplastic polyurethane is blended (in a kneader) with 1 to 5% w/w of double-unsaturated silicone rubber gum. The blend is then dynamically vulcanized by extruding (and pelletizing) it together with a peroxide curing agent like e.g. 1,3-bis-(t-butylperoxyisopropyl)benzene. The resulting thermoplastic is said to have improved slip resistance without reducing the TPU properties like abrasion resitance and is therefore said to be especially useful for the production of shoe-soles. It is ‘contemplated’ that the resulting material is a semi-IPN, but (i.m.o.) it is more likely that a seperate crosslinked silicone phase -and therefore a thermoplastic vulcanizate (TPV)- is formed.

1,3-bis-(t-butylperoxyisopropyl)benzene

Classic PU Patent of the Month: Polyurethane-Polyurea RIM Elastomers (Bayer 1976)

Title: VERFAHREN ZUR HERSTELLUNG VON ELASTISCHEN FORMKOERPERN

Number/Link: DE262295 (German)

Applicant/Assignee: Bayer

Publication date: 24-11-1977

“Gist”: Use of DETDA in one shot PU-PUA RIM.

Why it is interesting: This is the invention that for the first time allowed the production of large reaction injection moulded (RIM) polyurea articles with a very short demould time. Apart from advances in mixing head design which allowed for fast and accurate mixing and advances in mould design, polyurea RIM was made possible by the development of specific diamine chain extenders. Bayer found that aromatic diamines containing one alkyl group in o-postion to a first amino group and two alkyl groups in o-position to a second amine group, where at least two of the alkyl groups contain 2 or more carbon atoms, have the correct reactivity for a one shot RIM process when used together with conventional polyether polyols, MDI and catalysts. A preferred example of such a diamine is diethyltoluenediamine (DETDA). The use of DETDA in one shot RIM allowed for the production of parts up to 10 kg with a demould time of 30 seconds.

DETDA

Thermoplastic PU-PS Graft Copolymers

Title: POLYURETHANE-BASED POLYMER COMPOSITION

Number/Link: WO2014/147194

Applicant/Assignee: BASF

Publication date: 25-09-2014

“Gist”: TPU microparticles react with styrene monomer resulting in a TPU-PS copolymer.

Why it is interesting: Blends of TPU with polystyrene are known, but compatibility is low and PS to TPU ratio therefore needs to be low as well to prevent ‘delamination’ of injection moulded parts. According to this patent application it is however possible to graft the PS onto TPU such that much higher PS/TPU ratio’s can be obtained. The TPU needs to be MDI-based and have a relatively low hardblock content and softening temperature. Apparently the PS grafts onto the MDI methylene groups which form radicals easily. In an example TPU micropellets are swollen in styrene monomer at low temperature together with dicumulperoxide as a radical initiator. The swollen particles are then dispersed in water together with an emulsifier and heated under pressure to form a 60-40 TPU-PS copolymer. A solvent-based process is also exemplified. The resulting polymers are especially useful for injection moulded parts such as spring-aids.

MDI radical

Innovation in Polyurethanes

All posts tagged injection moulding

TPU-Silicone TPVs

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Classic PU Patent of the Month: Polyurethane-Polyurea RIM Elastomers (Bayer 1976)

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Thermoplastic PU-PS Graft Copolymers

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