POM Zhonghao Chemical K90

POM Zhonghao K90 is medium‑viscosity copolymer‑acetal(POM‑C) injection grade. Balanced mechanical property, standard flowability, good dimensional‑stability, broad service‑temperature window, good chemical‑resistance, excellent wear‑resistance & self‑lubrication, widely used for general‑purpose mechanical components。

Note: K90 is base grade；K90‑A is enhanced thermal‑stabilized version, adding high‑efficiency thermal stabilizer, less formaldehyde precipitation & mold deposit during long‑time production；mechanical parameters are basically consistent, K90‑A is more suitable for continuous mass production。

Main Applications

Automotive: gears, bearings, fuel‑system components, seat‑belt parts. Electrical & electronic: electrical components, connectors, structural & transmission parts for printer / copier OA‑equipment. Precision machinery & industrial parts: high‑precision gears, bearings, cams, screws, levers, pulleys with low‑friction & wear‑resistance requirement. Consumer goods: toys, sports‑equipment, zippers, fasteners, lighters; pipe fittings, conveyor accessories, water‑boiler parts, pump housing, strainers, faucet components。

Physical‑Mechanical‑Thermal Properties

Property Category	Item	Test Standard	Value	Unit
Physical Properties	Density	ASTM D‑792	1.41	g/cm³
	Water absorption (23 ℃,24 h)	ASTM D‑570	0.22	%
	MFR (190 ℃ / 2.16 kg)	ASTM D‑1238	9.0	g/10 min
	Molding shrinkage	—	2.0	%
Mechanical Properties	Tensile strength (yield)	ASTM D‑638	62	MPa
	Elongation at break	ASTM D‑638	60	%
	Flexural strength	ASTM D‑790	91.5	MPa
	Flexural modulus	ASTM D‑790	2650	MPa
	Izod notched impact (23 ℃)	ASTM D‑256	6.5	kJ/m²
	Tensile impact strength	ASTM D‑1822	110	ft·lb/in²
	Rockwell hardness M‑scale	ASTM D‑785	M80	—
Thermal Properties	HDT (1.8 MPa)	ASTM D‑648	110	℃
	HDT (0.45 MPa)	ASTM D‑648	158	℃
	Melting temperature	DSC	165	℃
	CLTE (20‑80 ℃)	ASTM E‑831	13×10⁻⁵	cm/cm/℃
Flammability	UL94 (0.8 mm)	UL 94	HB	—

Injection‑Molding Parameters

Process Stage	Parameter	Recommended Range	Unit	Remarks
Pre‑drying	Drying temperature	80‑90	℃	Drying recommended, avoid bubble & silver‑streak, improve dimension & surface quality。
	Drying time	2‑4	h
Barrel temperature	Rear zone	150‑180	℃	Narrow thermal window. Melt temperature ≤220 ℃, overheat causes formaldehyde decomposition。
	Middle zone	170‑190	℃
	Front zone	180‑200	℃
	Nozzle temperature	170‑190	℃	Slightly lower than front‑zone temperature to prevent drooling。
	Melt temperature(POM‑C)	190‑210	℃	Typical working range for copolymer POM。
	Mold temperature	80‑100	℃	Higher mold‑temperature improves crystallization, gloss and reduces sink‑marks。
Injection parameters	Injection pressure	40‑130	MPa	Higher for thin‑wall parts。
	Hold‑up pressure	Close to injection pressure	MPa	Sufficient hold‑pressure compensates shrinkage。
	Back pressure	0.5‑2.0(minimum preferred)	MPa	High back‑pressure brings shear‑overheat degradation。
	Injection speed	Medium‑fast	—	Too‑slow: flow marks; too‑fast: jetting & shear heat。
	Screw speed	100‑150	rpm	Avoid excessive screw‑speed; keep small cushion。
	Barrel residence time	＜20	min	Only 7 min maximum retention under 240 ℃。
Shutdown procedure	Short‑term stop	Cool barrel below 150	℃	Long‑term shutdown: fully purge with PE / PP。
	Purge note	PE / PP	—	Must purge halogen‑containing polymers before POM processing to prevent violent reaction。
Post‑treatment	Annealing(optional)	—	—	Relieve residual stress for high‑precision non‑ambient‑service parts。

Note: All data for reference only, subject to official TDS and COA。