WO2004069908A2

WO2004069908A2 - Zinc phosphate internal mold release agents

Info

Publication number: WO2004069908A2
Application number: PCT/US2004/001971
Authority: WO
Inventors: Lawrence A. Munie; James A. Faunce; Christopher A. Gariepy
Original assignee: Stepan Company
Priority date: 2003-01-28
Filing date: 2004-01-22
Publication date: 2004-08-19
Also published as: WO2004069908A3

Abstract

Zinc phosphate internal mold agents are disclosed. Methods of making the zinc phosphate internal mold release agents are also disclosed. The zinc phosphate internal mold release agents are made by reacting phosphate ester with zinc oxide.

Description

ZINC PHOSPHATE INTERNAL MOLD RELEASE AGENTS

RELATED APPLICATIONS

[0001] Priority is claimed from provisional application U.S. Serial No. 60/442,987, filed January 28, 2003, now pending. The entire specification and all the claims of the provisional application referred to above are hereby incorporated by reference to provide continuity of disclosure.

BACKGROUND OF THE INVENTION [0002] Internal mold release agents are typically used in the molding of composite materials. Typically, during the molding process the internal mold release agents migrate to the external surfaces of the composite molded material and provide the lubricity necessary to allow the composite to release from the mold. Phosphate esters and zinc stearates have been used as mold release agents.

[0003] Phosphate esters perform very well as mold release agents due to their acidic nature and their ability to navigate through the polymerizing resin and migrate to the surface to perform release functions. One drawback of phosphate esters, however, is that their acidity may cause an increase in metal die corrosion. Neutralization with amines is a common route to neutralize the acidity, but these and other additives only dilute the effectiveness of the phosphate ester as a release agent.

[0004] Zinc stearates are used as internal mold release agents in the manufacture of pultruded bulk molded and sheet molded components. The main reason for their use is low cost. Zinc stearate, however, has several inherent problems. Zinc stearate is a solid high melting temperature product which has to melt within the composite material, then migrate to the surface in order to be effective as an internal mold release agent. This limits the use of zinc stearate at lower temperatures. Also, since zinc stearate is a powder, there are issues usually associated with dusting (irritation). Additionally, high levels of powders such as zinc stearate mold release agents could cause concerns with explosions. BRIEF SUMMARY OF THE INVENTION

[0005] The present invention provides a zinc phosphate release agent, hi particular, the present invention is directed to the zinc salts of phosphate esters as internal mold release agents. The zinc phosphate has proven to be a superior release agent to amine neutralized products while maintaining good die corrosion resistance. The zinc phosphates of the present invention may be useful as internal mold release agents for the composite industry, specifically pultrusion and sheet and bulk molding compounds. Additional uses could range from metal working additives as a cleaner and lubricating agent. They may also be useful as antistatic agents in textiles.

BRIEF DESCRIPTION OF THE DRAWING

[0006] Figure 1 illustrates the results of the pultrusion dynamics pull force test and demonstrates that the zinc phosphate of the present invention reduced the pull force by 20% versus an industry standard of TECHLUBE CP-250.

DETAILED DESCRIPTION OF THE INVENTION [0007] The zinc phosphate release agent of the present invention can generally be described as a zinc neutralized phosphate ester or zinc salt of a phosphate ester. Typically, a phosphate ester is produced by the reaction of an alcohol and phosphorus pentoxide. The starting alcohol may be any alcohol having from 8 to 16 C atoms. The preferred alcohol is Cι₆H₃ OH which when reacted with phosphorus pentoxide produces a phosphate ester known by the tradename Zelec® UN manufactured and sold by Stepan Company of Northfield, Illinois. This reaction can be described as follows.

O

X — P-OH OH

ZELEC UN

[0008] The addition of zinc oxide to the phosphate ester can be described by the following reaction.

[0009] This reaction results in the following zinc phosphate release agents of the present invention.

O

II

~O — P- -O-Zn

OH and /or

and /or

Di Stuctures

O -P-O— Zn

O

Zn

[0010] The above-described reaction can be performed in the following way. A reaction vessel may be charged with the phosphate ester, preferably ZELEC® UN phosphate ester. The contents of the reaction vessel may then be mixed and sparged with nitrogen to drive off any water generated by the reaction. The contents of the reaction vessel may then be heated. The zinc oxide may then be added in an amount of about 4% to about 7%, preferably 5%, by weight based¹ on the weight of the phosphate ester, while continuing to heat and mix the contents of the reaction vessel. The reaction may proceed until the product is clear and possibly slightly yellow, but with no suspended particles visible to the naked eye.

[0011] For example, the reaction vessel may be charged with 932.5 grams of ZELEC® UN phosphate ester. The ZELEC® UN phosphate ester may be mixed and the mixture sparged with nitrogen to drive off any water generated by the reaction. The temperature may then be raised to approximately 125°C. At this point, 67.5 grams of zinc oxide may be added slowly to the reaction vessel. The temperature is held for one hour.

[0012] After one hour, the contents of the reaction vessel may be visually inspected for suspended particles. If particles are present, the temperature may be raised to 130°C for another hour of mixing at the increased temperature. After this additional resident time in the reaction vessel, the product may again be visually inspected for suspended particles. No particles should be present and the product should be clear and possibly slightly yellow. At this point, the product may be used as the mold release agent of the present invention.

Example 1 : Comparative Study Using A Pultrusion Dynamics Pull Force Test

[0013] The zinc phosphate of the present invention as prepared above was evaluated to demonstrate its utility as a mold release agent for composite materials, hi particular, a formulation with the following ingredients in the concentrations shown was prepared.

[0014] As noted in the table, the polymer used was polyester. The IMR - AGENT X-0006- 005 is the zinc phosphate of the present invention and performs the function of an internal mold release agent. The -MR - AGENT X-0006-005 was derived from the addition of zinc oxide to the ZELEC® UN phosphate ester as described above. The Perk 16 was a high reactive precarbonate and performed the function of a low temperature catalyst. The styrene was included to perform the function of diluent and solvent for the PERK 16. The

ESPEROX 10 was a t-butyl peroxybenzoate and performed the function of high temperature catalyst. The ASP-400P was a kaolin clay filler.

[0015] The composite material resulting from this formulation was subjected to a pultrusion dynamics pull force test and compared to other composites using standard internal mold release agents. The standard mold release agents used for comparison were TECHLUBE CP- 250 (Technick Products, hie, Rahway, New Jersey), AGENT 2609-83 (Stepan Company), AGENT 2468-37 (Stepan Company), and AGENT 2609-86 (Stepan Company). Figure 1 illustrates the results of the pultrusion dynamics pull force test and demonstrates that the zinc phosphate of the present invention reduced the pull force by 20%> versus an industry standard of TECHLUBE CP-250.

[0016] The invention has been described with reference to preferred and alternate embodiments. Modifications and alterations will occur to others upon the reading and understanding of the specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or equivalents thereof.

Claims

1. An internal mold release agent comprising a zinc phosphate.

2. An internal mold release agent comprising a zinc phosphate selected from the group consisting of:

O

OH

O II c. RO-P-O-Zn I O-Zn

e. mixtures thereof, wherein R , R , R , R , R , R and R are the same or different and each has from about 8 to about 16 carbon atoms.

3. The internal mold release agent of clahn 2, wherein R¹, R², R³, R⁴, R⁵, R⁶ or R⁷ has 16 carbon atoms.

4. The internal mold release agent of claim 2, wherein R¹, R², R³, R⁴, R⁵, or R⁶ is a Cι₆H₃₃- group.

5. The internal mold release agent of claim 2, wherein the internal mold release agent comprises a compound having the following structural formula:

O

T> — P O-Zn

OH

6. The internal mold release agent of claim 2, wherein the internal mold release agent comprises a compound having the following structural formula:

7. The internal mold release agent of claim 2, wherein the internal mold release agent comprises a compound having the following structural formula:

8. The internal mold release agent of claim 2, wherein the internal mold release agent comprises a compound having the following structural formula:

O II

ΛΛΛΛΛΛΛΛO-P-O-Zn I O-Zn

9. A method of making an internal mold release agent comprising the steps of: a. providing phosphate ester into a reaction vessel; b. sparging the reaction vessel with an inert gas; c. adding zinc oxide to the reaction vessel in an amount of from about 4% to about 7% by weight based on the weight of the phosphate ester to form a reaction mixture;

and d. heating the reaction vessel until the reaction mixture is substantially free of suspended particles.

10. The method of claim 9, wherein the inert gas is nitrogen.

11. The method of claim 9, wherein the zinc oxide is added in an amount of about 5% by weight based on the weight of the phosphate ester.

12. The method of claim 9, wherein the phosphate ester has the following formula:

wherein R has from about 8 to about 16 carbon atoms.

13. The method of claim 12, wherein R has 16 carbon atoms.

14. The method of claim 9, wherein the phosphate ester is added to the reaction vessel at an ambient temperature.

15. The method of claim 9, wherein the phosphate ester is heated less than about 125°C during the sparging of the inert gas prior to the addition of the zinc oxide to the reaction vessel.

16. The method of claim 15, wherein the zinc oxide is added to the reaction vessel to form the reaction mixture when the temperature of the reaction vessel is about 125°C.

17. The method of claim 16, wherein the reaction mixture is heated from about 125°C to about 130°C for a sufficient period of time until the reaction mixture is substantially free of suspended particles..

18. The method of claim 17, wherein the reaction mixture is maintained at a temperature of about 125°C.

19. The method of claim 17, wherein the sufficient period of time is about one hour or greater.

20. The method of claim 18, further comprising the steps of: inspecting the reaction mixture for suspended particles after the reaction mixture is maintained at a temperature of about 125 °C for approximately one hour; and if suspend particles remain, increasing the temperature of the reaction mixture to about 130 °C and maintaining the increased temperature until the reaction mixture is substantially free of suspended particles.