Internal Mould Release Agent Research Articles

Synthesis and Conformational Relationship of New Fluorinated Acrylate Polymer‐Based Internal Mold Release Agents

ABSTRACTThis study employed short fluorocarbon chain perfluorohexylethyl methacrylate (PFOL, Rf = 6) and long hydrocarbon chain Stearyl acrylate (SA, R = 18) to synthesize a series of fluorinated acrylate polymers (FAP) via solution polymerization. The copolymerization rates of PFOL and SA were calculated, and the copolymer composition curves were plotted to produce FAP with uniform composition and varying PFOL ratios. Experiments revealed that these FAP demonstrated significant dissolution and migration behaviors during the processing of fluoroelastomers, influenced by the PFOL to SA ratio. The optimized FAP (PFOL ratio of 0.7), with a weight‐average molecular weight between 23,000 and 26,000, significantly reduced the demolding force of fluoroelastomer O‐rings from 49 to 20 N. Water contact angle and demolding force tests further verified the internal mold release effects of the FAP. Predictions from the CISOC‐PSAT program indicate that the FAP synthesized in this study is less toxic compared to the copolymer of perfluorooctylethyl methacrylate (POEMA) and SA, with negative results for carcinogenic and mutagenic toxicity, demonstrating its potential as an environmentally friendly, green fluorine‐containing internal mold release agent.

The adhesion of aluminium inserts in epoxy composites: The role of surface pre-treatment

Aluminium inserts are frequently embedded within the composite sandwich structures used in modern sports cars. Since the inserts are used for attaching safety-critical components to the structure, the adhesion between the metal and composite needs to be strong and durable. The bond is achieved through an epoxy resin system. However, when the resin includes an internal mould release agent (IMR) to facilitate the demoulding process of the structure, the adhesion between the inserts and the composite structure can be compromised. In addition, inserts can be exposed to high treatment temperatures. As such, to ensure that high adhesion performance can still be achieved, an appropriate surface treatment should be applied on the inserts.In this paper, four commercially available surface treatments for aluminium inserts were assessed using single lap joint (SLJ) and double cantilever beam (DCB) tests. Moreover, to investigate the influence of the IMR and the high-temperature process on the joint properties, four sample manufacturing methods were used to prepare the SLJ samples: without IMR and without high-temperature process (Method 1), with IMR (Method 2), with high-temperature process (Method 3) and with both IMR and high-temperature process (Method 4). The DCB samples were only prepared using Method 4. The locus of failure for the SLJ samples prepared with Method 4 was evaluated by using X-ray photoelectron spectroscopy (XPS) and optical microscopy. It was found that a silane-based primer was sensitive to the use of both the IMR and high temperature (31% drop in the lap joint strength when both applied). A cataphoretic electrocoat was also investigated and only deteriorated when exposed to high temperature (up to 40% decrease in the lap joint strength). An epoxy-based primer did not show a significant sensitivity to the IMR, however, when exposed to high-temperatures, the joint became even stronger (up to 15% increase in the lap joint strength).

Effect of internal mold release agent on flexural and inter laminar shear properties of carbon and glass fabric reinforced thermoset composites

The study is focused on thermoset composites reinforced with carbon and glass woven fabrics. Two types of thermoset resins, for example, epoxy and vinyl ester were used as the matrix. Varying concentrations of internal mold releasing (IMR) agent was used in the resin. The composites were cured both at room temperature and at 80°C. The flexural properties were studied using 3‐point bending test method. Further theinter‐laminar shear strength (ILSS) was investigated using the short beam shear strength test based on 3‐point bending. The flexural modulus of room temperature cured epoxy resin is higher than that of high temperature cured epoxy resin and cured vinyl ester resin. The flexural modulus is lowest for 1% IMR sample in epoxy system and the modulus for 0% and 2% epoxy are not significantly different. Lowest flexural strength and modulus can be observed for the combination of reinforcement and curing conditions for samples containing 1% IMR for the epoxy systems. Carbon fiber is found to be less compatible with the vinyl ester resin system and the addition of IMR to the resin degraded the properties further. Inter‐laminar shear strength for epoxy‐based composites is not much affected by presence of IMR, but in case of vinyl ester based composites there is a decrease in ILSS on addition of IMR agent. The study explains variation in flexural properties on addition of IMR and change of curing conditions. These results can be used for ascertaining variation in mechanical properties in real use.

Development of a dilatometer for shrinkage analysis of thermosetting resin systems at accurate processing conditions of liquid composite moulding processes and exemplary results of the effects of varying processing conditions on chemical shrinkage of an epoxy resin

The processing of thermosetting resin systems in liquid composite moulding is accompanied by a change in density through chemical and thermal shrinkage during the curing reaction of the resin and cooling of a part from processing to operating temperature. These effects cause residual stresses and an undesired characteristic surface pattern in endless fibre reinforced plastics. However, the accurate measurement of the chemical and thermal shrinkage is challenging with state-of-the-art measurement devices, especially for highly reactive thermosetting resin systems. The main disadvantage is that it is not possible to recreate the processing conditions of modern liquid composite moulding processes during the measurement of the thermosetting resin systems and has therefore limited use for process optimisations. In this paper the development of a dilatometer, which is capable of measuring the shrinkage in highly reactive thermosetting resins providing the processing conditions of liquid composite moulding is presented. The effects of processing pressure and internal mould release agents on chemical shrinkage are analysed with the developed dilatometer for different epoxy resins. The trials demonstrate a significant effect of processing pressure on chemical shrinkage.

New process aids from Croda

UK-based Croda Chemicals has launched a new range of internal mould release agents for injection moulding as well as expanding its Incroslip range of slip additives for plastic closures. The new additions received their debut at the recent NPE 2003 show in Chicago, USA. This is a short news story only. Visit www.addcomp.com for the latest additives and compounding industry news

Mould releases improve surface finish

UK company Croda's new range of internal mould release agents claims to offer improved surface finish, continuous running and increased production output for plastic mouldings. This is a short news story only. Visit www.addcomp.com for the latest additives and compounding industry news.

Phase separation in styrenated polyester resin containing a PVAc low profile additive and metallic stearates

Unsaturated Polyester Resins(UP) that contain compatible low-profile additives (PVAc) are used in BMC composite materials (Bulk Molding Compound). The general morphology of the UP/PVAc matrix is made up of small polyester nodules embedded in a matrix-rich thermoplastic additives. An internal mold-release agent (often a Calcium Stearate) is incorporated into the UP/PVAc mixture to facilitate the extraction of the curing materials. Although used in small quantity, this agent does have an effect on the final morphology of the curing mixture. Some of the internal mould-release agents provoke the formation of a polyester rich phase in the form of large spherical globules (roughly 60 micrometers). The formation of the “globular” polyester phase seems to depend largely on the nature of the metallic ion and the solubility (in the styrene) of the mould-release agent. If this phase occurs, most of the internal mould-release agents are trapped inside the polyester globules. Given its particular affinity for mineral materials, this phase tends to coat filler and glass fibbers. Consequently, this phase strongly conditions the mechanical characteristics of the final composite.

Behavior of internal mold release agent during BMC thermosets composites cure and aging

Behavior of internal mold release agent during BMC thermosets composites cure and aging

Effect of internal mold release agent on the cure and property variation in resin transfer molding composites

Effect of internal mold release agent on the cure and property variation in resin transfer molding composites

Caractérisation de surface de composites de type BMC

The car manufacturing industry tends to replace steel panels by composite materials such as unsaturated polyester matrices reinforced by glass fibers and filled with calcium carbonate. Sheet moulded compounds -SMC- and bulk moulded compounds -BMC- are the two possible types of such composites. Here, we are interested in the knowledge of the surface characteristics of BMC composites in order to predict their behavior in adhesive joints. Different complementary techniques of the surface analysis (SEM, ESCA, TOF-SIMS, SDL and wettability) allowed us to reach the goal. We were particularly interested in the influence of the concentration and the nature of the internal mould release agents (zinc or calcium stearate) introduced in the compounds on the surface properties of the composites.

US 4,946,922 Internal mould release agent for polyisocyanurate foams

US 4,946,922 Internal mould release agent for polyisocyanurate foams

Internal mould release agent for use in reaction injection moulding

Additive Manufacturing (AM) has the potential to facilitate the limitless design and fast fabrication of silicone structures with controllable internal features and heterogeneous properties. The challenging task of developing AM systems able to handle viscous thermosetting silicones is reviewed in this work, with a focus on their use for biomedical applications. Moreover, the development of silicone tailored for AM is reviewed by examining three areas of curing mechanisms, rheological properties, and mechanical performance.

Internal mould release agent for use in moulding polyurethanes and/or polyurea

Internal mould release agent for use in moulding polyurethanes and/or polyurea

Internal mould release agent for use in reaction injection mouldings

Internal mould release agent for use in reaction injection mouldings

Fabrication of Microstructures of Extreme Structural Heights by Reaction Injection Molding

Abstract For the fabrication of microstructures with minimum lateral dimensions in the micrometer range and structural heights of up to several hundred micrometers a new microfabrication technique has been developed by the Karlsruhe Nuclear Research Center. The so-called LIGA method is based on a combination of deep-etch X-ray-lithography, electroforming and plastic molding. High-quality micromold inserts can be prepared by deep-etch X-ray lithography and electroforming allowing an arbitrary choice of cross section of the microstructures. By optimization of the process parameters of the reaction injection molding process using casting resins on a methyl methacrylate base it has been shown that a yield of 100% can be achieved. For molding microstructures without any flaws, the mold material has to be degassed, the cavity of the mold must be evacuated and the shrinkage due to polymerization has to be compensated by applying a holding pressure. With an internal mold release agent which is a special salt of an organic acid, cycle times of about 12 min have been achieved in the micromolding process step which are very much shorter than the exposure and development times in the direct lithographic production of microstructures. Such plastic structures can represent the final product or, if microstructures are to be made of metal, they are used as templates in a subsequent electroforming process. Depending on the geometrical configuration of the microstructures, either a metallic gate plate or an electrically conducting plastic layer are used as the electrode for electroforming.

Fabrication of microstructures with extreme structural heights by reaction injection molding

AbstractFor fabrication of microstructures with extreme structural heights a reaction injection micromolding process has been developed. It uses mold inserts produced by deep‐etch X‐ray lithography and electroforming which have superior surface quality with a surface roughness Rmax of less than 0.02 μm. For methyl methacrylate base casting resins in combination with an internal mold release agent the molding conditions have been optimized on a laboratory‐scale reaction injection molding machine and correlated with thermomechanical measurements. It has been demonstrated by many experiments that in spite of minimum lateral dimensions of only some micrometers and structural heights of some hundred micrometers a yield of approximately 100 % can be obtained in the micromolding process. This new process may be applied for producing innovative microstructure products, e.g. in the fields of sensors, packaging and interconnection in microelectronics, filtration, microoptics and synthetic fibers.

Fabrication of microstructures with high aspect ratios and great structural heights by synchrotron radiation lithography, galvanoforming, and plastic moulding (LIGA process)

Under the LIGA process for fabricating microstructures having high aspect ratios and great structural heights, synchrotron radiation lithography produces a primary template which is filled with a metal by electrodeposition. The metallic structure so produced is used as a mould insert for fabricating secondary plastic templates which, in mass production, replace the primary template. This is a report about the status of work performed by the Karlsruhe Nuclear Research Center with the cooperation of Siemens AG and the Fraunhofer Institute for Solid State Technology: By irradiation and development of polymethyl methacrylate (PMMA) plates, primary templates were produced which, for structural heights of several hundred μm, exhibit deviations in critical dimensions of less then some 0.1 μm. The best results were obtained with an X-ray mask consisting of a 25 μm thick beryllium foil and 18 μm thick absorber structures consisting of copper and gold. Practically perfect metallic replicas were obtained by electrodeposition of nickel in the PMMA microstructures and even details in structure of less than 0.1 μm size were reproduced. Moulding was done with a methacrylate-based casting resin with an internal mould release agent. By electrodeposition of nickel in the secondary templates, secondary metal structures were produced which practically do not differ from the primary structures. The LIGA process can be expected to be superior to other methods for fabricating microstructures with high aspect ratios if, in series production of microstructures with complex shapes, stringent requirements are imposed on the resolution, the aspect ratio, the structural height, and the parallelism of the structural walls.