Patent Application
20160096958
1. Field of Invention
This invention is related to a thermosetting material, and is more particularly to a shape memory thermosetting epoxy.
2. Description of the Related Art
Epoxy became popular in commercial use in 1950. Epoxy was commonly used to spray on circuit boards and electronic components because epoxy has stable material properties. Chemical bonds of epoxy like epoxide groups, amino group and hydroxyl group were linked into a rigid 2-D or 3-D structures in curing processes that leads epoxy became more stable and resistible.
First material being known to have shape memory properties is shape memory metal alloy (SMA) been discovered by Chang et al. in 1952. TiNi (Nitinol), CuZnAl and FeNiAl alloys are three major type of SMAs. These materials have been proposed for various uses in aeronautical, electronic and mechanical industry. SMAs were limited to be used on specific products because of high cost issues. Shape memory polymer (SMP) has been successfully developed and widely used because of lower costs and easier for production. Polyvinyl methyl ether (PVME), polyvinyl acetate (PVA), 1,4-trans polyisoprene (TPI), polyethylene (PE), polystyrene (PS) and polyurethane (TPU) are some of SMP being discovered. The above mention of SMP still can't widely used in industry because of weak intensity and rigidity.
In order to solve the disadvantages and shortcoming of the SMP such as weak intensity and rigidity, the present invention provides a producing method of a shape memory thermosetting epoxy including steps of:
mixing a modifying material and a cross-linking agent to form a pre-polymer;
mixing epoxy, the pre-polymer and a functional material to form a first mixed agent;
mixing a curing agent and the major blending agent to form a fluid shape memory thermosetting material; and
molding the fluid shape memory thermosetting material into required shape.
Thus, the present invention achieves advantages as below.
1. The present invention is shape memory thermosetting material which is deformable in certain range of temperature and is shape memorable under room temperature.
2. The present invention may be shaped as required shape by demand with very simple method.
3. The present invention is fluid before shaping as required shape and may be deformed under wide range of temperature by adjusting the content of the cross-linking agent.
4. The present invention is suitable for various molding process like compression molding process or injection molding process which is able to reduce at least 70% of mould costs for producing large product items.
With reference to
STEP 1. mixing a modifying material and a cross-linking agent for about 2˜4 hours to form a pre-polymer. The modifying material may be polyester polyol, polyether polyol, aromatic diamine or silicone compounds. The cross-linking agent may be a polyamine cross-linking agent.
Producing the pre-polymer may have steps comprising of (1) stirring the modifying material in a reaction flask in low speed by a blender; (2) heating to a certain temperature (e.g. 80° C.+/−); and (3) adding the cross-linking agent slowly and stirring continually to form the pre-polymer. Stirring time thereof may be 2˜4 hours.
STEP 2: mixing epoxy, the pre-polymer and a functional material uniformly to form a major blending agent. Mixing time thereof may be but not limited to 3˜7 minutes. The functional material may be but not limited to boron trifleoride, terminal carboxyl group, calcium carbonate, unsaturated polyester, phenolic resin, pigment, polyamine, antifoaming agent, surfactant or phenyl solvent. The phenolic resin is selected from a group consisted of bisphenol-A phenolic resin, novolac resin, methylphenyl novolac resin, bisphenol-A novolac resin, phenol aralkyl resin, dicyclopentadiene phenolic novolac resin, amino triazine phenolic novolac resin, polybutadiene phenolic novolac resin, biphenyl type resin and mixture thereof.
The major blending agent may be prepared by blending the epoxy with the pre-polymer and the functional material in a container for few minutes such like 5˜10 mins by a blender with 1000 RPM+/−10% to form the major blending agent.
STEP 3. mixing a curing agent and the major blending agent to form a fluid shape memory thermosetting material. The curing agent may be fatty amine, polyamide or aromatic amino compound.
STEP 4. molding the fluid shape memory thermosetting material into required shape. The fluid shape memory thermosetting material can be molded by an infusion process, a spray process, a blade coating process, a hot-pressing process and a resin transfer molding process.
In a preferred embodiment, the fluid shape memory thermosetting material consists in the major blending agent for 30 wt %˜95 wt %, the modifying material for 2 wt %˜50 wt % and the functional material for 0.1 wt %˜10 wt %. The fluid shape memory thermosetting material is able to be reshaped as a required shape under a temperature range around 80° C.˜160° C.
Shape memory ability mechanism of the present invention may be stated as followings. The cross-linking agent and the curing agent are respectively selected to have different reaction rates with the major blending agent. The cross-linking agent is first added to activate a cross-link reaction with the major blending agent. The cross-link reaction may be a substitution reaction with side-chains to the major blending agent. The curing agent acts like an inhibitor being added to terminate the cross-link reaction. Because molecular weight of the curing agent is smaller than the cross-linking agent, the curing agent has faster reaction rate than the cross-linking agent. The major blending agent then comprises a network structure for shaping as required shape at designed temperature range.
Step 1. Mixing 20 wt % of the modifying material and 5 wt % of the cross-linking agent for 20 minutes to form the pre-polymer;
Step 2. mixing 50 wt % of the major blending agent, 0.5 wt % of antifoaming agent, 0.5 wt % of surfactant and the pre-polymer for 5˜10 minutes;
Step 3. mixing 30 wt % of the curing agent and the major blending agent then stirring continually for 3 minutes to form the fluid shape memory thermosetting material;
Step 4. pouring the fluid shape memory thermosetting material into a mould and a shape memory thermosetting epoxy is formed after curing.
The present invent also provide an automatic shape memory film which is able to be mounted smoothly on skin surface of human's body. The automatic shape memory film is able to attach with other material and has centimeter to millimeter of thickness.
According to the above mentioned, the invention has advantages listed as below:
1. The present invention is shape memory thermosetting material which is deformable in certain range of temperature and is shape memorable under room temperature.
2. The present invention may be reshaped by demand.
3. The present invention is fluid before shaping as required shape and may be deformed under wild range of temperature by adjusting the content of the cross-linking agent.
4. The present invention is suitable for various molding process like hot-pressing process or injection molding process which is able to reduce at least 70% of mould costs for producing large product items.
