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Syntactic foam plugs

a technology of syntactic foam and thermoplastic matrix, which is applied in the field of thermoplastic matrix syntactic foam plugs, can solve the problems of affecting the stretching of the molten web to be formed into a high quality part, increasing the operating cost, and adding complexity to the device, so as to reduce or avoid the need for additional operations, reduce the undesirable characteristics of thermoset syntactic plugs, and reduce the effect of glass transition temperatur

Inactive Publication Date: 2006-08-03
CAMPBELL RICHARD W +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The thermoplastic syntactic foam plugs exhibit improved mechanical toughness, reduced thermal conductivity, and easier machining, leading to increased tool life, reduced operational costs, and simplified manufacturing, while maintaining low thermal conductivity benefits, enabling the production of high-quality, uniform thermoformed parts.

Problems solved by technology

Primarily each of these suffer from their relatively high thermal conductivity which removes heat from the molten web and thus adversely affects the stretching of the molten web to be formed into a high quality part.
These deficiencies may be at least partially overcome through the use of internal or external heating of the plug or employing a multi-component plug but this adds complexity to the device, to the operation and increases the operating cost.
However, these plug assists lack the mechanical toughness desired for the application.
They are easily damaged during the operation or during the frequent tool changes typical of their usage and once a dent or chip occurs in a critical area, the tool is unacceptable and must be reworked or scrapped.
In addition, it is difficult to machine a brittle epoxy form.
The thermoset syntactic foam can chip during machining and the removed materials turn to dust.
Once this occurs, machine wear issues are created.
Also, most often the machinist must wear protective equipment to avoid dust inhalation and spend additional time to clean up the area after machining.
Although there are recognized advantages and disadvantages to using syntactic materials for plugs, it was believed that the relatively high operating temperature demands of thermoforming operations limited the selection of syntactic materials to thermoset matrix syntactic materials.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 5

[0028] Syntactic foam plugs were prepared on an industrial scale from the formulation set forth in Table 2-A. The industrial scale process for the poymerization included adding melted caprolactam (monomer) to a closed mixer maintained under nitrogen. The microspheres filler, initiator, stabilizer and pigment were added under nitrogen in such a manner that excludes moisture and air. The temperature of the mixture was then raised to 145° C. and the vessel evacuated to less than 25 mm Hg to remove entrained air and other volatiles. The vacuum was broken with nitrogen and the evacuation cycle was repeated 2-3 times. The mixture was then transferred to a mold preheated to 160-170° C. for polymerization. The catalyst was added to and mixed with the monomer mixture as the material was being transferred into the mold. After polymerization, the solid object was removed from the mold and annealed for stress relief.

TABLE 2-AWeight, lbs. (Kg)Weight (%)Caprolactam56.65 (25.72)79.78K20 Glass 9....

example 6

[0031] Industrial scale plugs were prepared in a thermoforming process from a formulation corresponding to Example 4 (45 Vol. % of S22 microspheres) having properties as shown in Table 3.

TABLE 3PropertyExample 5ASTMDensity (ρ)43-47 lb / ft3D-792[740 kg / m3]Specific Heat (Cp)0.43 BTU / lb ·° F.E-1530per mass[1.80 kJ / (kg ·° C.)]Coefficient of28 × 10−6 in / in / ° F.E-831Thermal Expansion[50 × 10−6 m / m / ° C.](CTE) (21-150° C.)Compressive6,300 psiD-645Strength[43.4 Mpa]Compressive180 KpsiD-645Modulus[1.24 Gpa]Service350° F.N / ATemperature[180° C.]

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Abstract

The present invention provides an improved syntactic foam plug for plug assist thermoforming wherein such plug is composed of a thermoplastic material having a relatively high melting and / or glass transition temperature. Accordingly, the subject invention encompasses diminishing or removing the undesirable characteristics of thermoset syntactic plugs while increasing the ease by which these articles may be constructed for a given use, by forming such plugs from syntactic foams containing thermoplastics.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This is a Continuation of International Application No. PCT / NL00 / 00536 filed Jul. 27, 2000 which which designated the U.S. and was published in the English language. This application also claims the benefit of U.S. provisional application 60 / 145,821 filed Jul. 27, 1999. The contents of both the PCT application and the provisional application are incorporated in their entirety by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to thermoplastic matrix syntactic foam plugs for use in plug assist thermoforming and the process of making and using the same. In particular, the present invention relates to forming syntactic foam plugs from thermoplastic matrix material having a melting temperature and / or glass transition temperature at least 5° C. higher than the operating design temperature of the thermoforming process. [0004] 2. Background Art [0005] A plug, or plug assist, is a male tool u...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B29C33/40B29C49/04B29C51/04C08J9/32
CPCB29C49/04B29C51/04B29K2023/06B29K2023/12B29K2025/00B29K2027/06B29K2033/26B29K2069/00B29K2075/00B29K2077/00B29K2101/12B29K2105/0085B29K2105/04B29K2105/16B29K2105/165B29L2031/7132C08J9/32C08J2203/22C08J2377/02Y10T428/249953
Inventor CAMPBELL, RICHARD W.TESSIER, NOEL J.
Owner CAMPBELL RICHARD W