CN104761263A - Adhesive for powder injection molding and preparation method of adhesive - Google Patents

Abstract

The invention provides an adhesive for powder injection molding and a preparation method of the adhesive. The adhesive is composed of the following components in percentage by weight: 60-85% of polyethylene glycol, 10-35% of polymethyl methacrylate and 1-10% of stearic acid. The preparation method comprises the following steps: (a) dissolving a proper amount of polymethyl methacrylate in acetone at room temperature; (b) adding the polymethyl methacrylate acetone solution into a kneading machine for mixing the same with powder, and stirring uniformly; (c) heating up the kneading machine to 60-120 DEG C to completely volatilize acetone; (d) heating up the kneading machine to 120-160 DEG C, adding polyethylene glycol, and stirring until obtaining a uniform feed; (e) injecting the feed, and removing organic matters from a blank body through a siphon heat degreasing process, wherein the surfactant stearic acid can be added in a ball milling or wet mixing process of the powder or added with the polyethylene glycol. According to the adhesive provided by the invention, special polymethyl methacrylate micropowder with ultra-high molecular weight is replaced by universal polymethyl methacrylate micro powder, so that the cost of the adhesive is lowered, and thus the adhesive is suitable for industrial production.

Description

A kind of powder injection forming binding agent and preparation method thereof

Technical field

The invention belongs to Powder Injection Molding Technology field, more particularly, the present invention relates to a kind of powder injection forming binding agent and preparation method thereof.

Background technology

Powder injection forming is the near net shape technology developed rapidly in the world in recent years, it is advantageous that and high-level efficiency can manufacture the finding of high shape complexity in large quantity.The key of this technology is the selection of binding agent and its feedstock preparation and degreasing method.Uniformity wanted by desirable feeding, meets zero defect injection and degreasing performance requriements.

The commercial binder system of wax-based binder system and polyoxymethylene base obtains large-scale application but technique relates to poisonous harmful operations.Along with the enhancing of environmental consciousness, water degreasing binding agent obtains the concern of Chinese scholars with its environmental friendliness.Polyoxyethylene glycol (PEG)+polymethylmethacrylate (PMMA)+stearic acid (SA) system of Univ Sheffield UK's exploitation, by adopting the special ultra-high molecular weight polymethylmethacrylate micro mist produced, solve the swelling problem during degreasing of base substrate water, but ultra-high molecular weight polymethylmethacrylate micro mist is external particular vendors adopts special process to produce, be difficult to obtain and expensive, make it to be difficult to obtain heavy industrialization application.

Summary of the invention

The object of the present invention is to provide a kind of powder injection forming binding agent and preparation method thereof, solve the problems of the technologies described above.The present invention substitutes the special polymethylmethacrylate micro mist of ultra-high molecular weight with general polymethylmethacrylate micro mist, adopts a step siphon thermal debinding method degreasing, reduces binding agent cost, make it to be applicable to suitability for industrialized production.

A kind of powder injection forming binding agent of the present invention, this binding agent is composed of the following components by weight percentage:

Polyoxyethylene glycol 60% ~ 85%

Polymethylmethacrylate 10% ~ 35%

Stearic acid 1% ~ 10%

In above-mentioned binding agent, polyoxyethylene glycol is mobility constituent element, provides feeding mobility; Polymethylmethacrylate is aggregate, provides blank strength; Stearic acid is tensio-active agent, improves powder and binding agent bonding strength.

The molecular weight polyethylene glycol that binding agent of the present invention is selected is between 1,000 6000, and the polymethylmethacrylate molecular weight selected, between 40,000 600000, is universal polymethylmethacrylate micro mist.

A kind of powder injection forming binding agent preparation method of the present invention is made up of following steps:

By appropriate polymethylmethacrylate acetone solution under (a) room temperature;

B polymethylmethacrylate acetone soln adds in kneader and mixes with powder and stir by ();

C () kneader is warming up to 60 120 ° of C makes acetone volatilize completely;

D () kneader is warming up to 120 160 ° of C, add polyoxyethylene glycol and stir until obtain uniform feeding;

E after the injection of () feeding, base substrate removes organism by siphon thermal debinding process.

Wherein tensio-active agent stearic acid can when powder ball milling, wet-mixed time or add together with polyoxyethylene glycol.

The invention has the advantages that:

1. binding agent and preparation and degreasing method belong to environmentally friendly, operate without poisonous and harmful;

2. binding agent adopts universal polymethylmethacrylate micro mist, and cost is low.

Embodiment

Embodiment 1

Binding agent each constituent element molecular weight and massfraction as follows:

	Molecular weight	Weight ratio
			Polyoxyethylene glycol	1500	75%
Polymethylmethacrylate	200000	20%
			Stearic acid		5%

At room temperature by polymethylmethacrylate acetone solution, add in kneader and mix with import alumina powder and stir, kneader is warming up to after 90 ° of C treat acetone evaporated, be warming up to 150 ° of C, add polyoxyethylene glycol and stearic acid and stir until obtain uniform feeding, feeding alumina powder loading capacity is 53%.Be shaped at injection temperature 150 ° of C, injection pressure 90MPa hemostasis, after injection, base substrate removes organism by siphon thermal debinding process, and 1650 ° of C air atmosphere sintering obtain alumina-ceramic relative density and reach 93%, and comprehensive mechanical property is good.

Embodiment 2

Binding agent each constituent element molecular weight and massfraction as follows:

	Molecular weight	Weight ratio
			Polyoxyethylene glycol	4000	80%
Polymethylmethacrylate	500000	15%
			Stearic acid		5%

At room temperature by polymethylmethacrylate acetone solution, add in kneader and mix with domestic alumina powder and stir, kneader is warming up to after 90 ° of C treat acetone evaporated, be warming up to 140 ° of C, add polyoxyethylene glycol and stearic acid and stir until obtain uniform feeding, feeding alumina powder loading capacity is 50%.Be shaped at injection temperature 140 ° of C, injection pressure 90MPa hemostasis, after injection, base substrate removes organism by siphon thermal debinding process, and 1650 ° of C air atmosphere sintering obtain alumina-ceramic relative density and reach 91%, and comprehensive mechanical property is good.

Embodiment 3

Binding agent each constituent element molecular weight and massfraction as follows:

	Molecular weight	Weight ratio
			Polyoxyethylene glycol	2000	60%
Polymethylmethacrylate	300000	33%
			Stearic acid		5%

After domestic alumina powder adds appropriate stearic acid, ball milling obtains ball milling powder, at room temperature by polymethylmethacrylate acetone solution, add in kneader and mix with ball milling powder and stir, kneader is warming up to after 90 ° of C treat acetone evaporated, be warming up to 140 ° of C, add polyoxyethylene glycol and stir until obtain uniform feeding, feeding alumina powder loading capacity is 50%.Be shaped at injection temperature 140 ° of C, injection pressure 90MPa hemostasis, after injection, base substrate removes organism by siphon thermal debinding process, and 1650 ° of C air atmosphere sintering obtain alumina-ceramic relative density and reach 92%, and comprehensive mechanical property is good.

Claims (3)

1. a powder injection forming binding agent, is characterized in that: described binding agent is composed of the following components by weight percentage:

Polyoxyethylene glycol 60% ~ 85%

Polymethylmethacrylate 10% ~ 35%

Stearic acid 1% ~ 10%.

2. powder injection forming binding agent according to claim 1, is characterized in that: described molecular weight polyethylene glycol is 1,000 6000, and polymethylmethacrylate molecular weight is 40,000 600000.

3. a preparation method for powder injection forming binding agent, is characterized in that: described preparation method comprises the following steps:

By appropriate polymethylmethacrylate acetone solution under (a) room temperature;

B polymethylmethacrylate acetone soln adds in kneader and mixes with powder and stir by ();

C () kneader is warming up to 60 120 ° of C makes acetone volatilize completely;

D () kneader is warming up to 120 160 ° of C, add polyoxyethylene glycol and stir until obtain uniform feeding;

E after the injection of () feeding, base substrate removes organism by siphon thermal debinding process;

Wherein tensio-active agent stearic acid can when powder ball milling, wet-mixed time or add together with polyoxyethylene glycol.