摘要:
A pre-expanded particle suitable for foaming in a mold comprising polyolefin which has a characteristic property that an inclination of slope line obtained on a graph when logarithmic values of melt tension of the polyolefin are plotted as ordinate and reciprocals of absolute temperature at which the melt tension is measured are plotted as abscissa is less than 1,500 is provided. A foamed article produced from the pre-expanded particles has an excellent appearance, a flat surface and good mechanical strength, and is useful for wrapping material, insulating material, a container or a fender of cars.A process for preparing the above-mentioned pre-expanded particles is also disclosed.
摘要:
The mixture of water and the polyolefin resin particles impregnated with a volatile blowing agent are released from the interior of the pressure-resistant container under a constant temperature and constant pressure preferably keeping the partial pressure of the blowing agent constant, through at least one orifice having an area of 0.07 to 300 mm.sup.2, into a low-pressure zone.This invention gives various advantages when applied to the practical process resulting in expanded particles with superior properties which are free of blocking and remarkably uniform in the degree of expansion, and are useful for molding.
摘要:
A pre-expanded particle suitable for foaming in a mold comprising non-crosslinked linear low density polyethylene which has a characteristic property that an inclination of slope line obtained on a graph when logarithmic values of melt tension of the polyolefin are plotted as ordinate and reciprocals of absolute temperature at which the melt tension is measured are plotted as abscissa is not more than 1,500 is provided. A foamed article produced from the pre-expanded particles has an excellent appearance, a flat surface and good mechanical strength, and is useful for wrapping material, insulating material, a container or a fender of cars.
摘要:
A pre-expanded particle made of a blend of 10 to 90% by weight of a polypropylene resin having a melt index of 6 to 10 g/10 minutes and 90 to 10% by weight of a polypropylene resin having a melt index of 0.5 to 3 g/10 minutes. The melt index of the blend being within the range of 2 to 5 g/10 minutes. The pre-expanded particles can be molded by an in-mold foaming method in a short time without causing sink to give polypropylene resin cellular molded articles having good surface property and good melt adhesion of the particles.
摘要:
An injection-molding process including kneading functional particles with a binder resin in a kneader, temporarily storing the kneaded material supplied from the kneader in a reservoir device and feeding the kneaded material stored in the reservoir device to an injection device, the reservoir device including a pair of reservoirs, the kneaded material stored in one reservoir device is fed to the injection device where the kneaded material is then injection-molded, and simultaneously the kneaded material is fed from the kneader to another reservoir device and stored in it. Then, the kneaded material stored in the other reservoir device is fed to the injection device where the kneaded material is then injection-molded, and simultaneously the kneaded material is fed from the kneader to the one reservoir device and stored in it, so that the injection molding process is conducted by alternately repeating the above steps by switching operations. This injection-molding process is capable of producing a molded product of uniform quality by preventing feed pressure of the kneaded material fed to an injection device from being transmitted to the kneader.
摘要:
An injection-molding device including an injection machine, a mold unit connected to the injection machine having separable molds defining a cavity for forming a molded product, and chucks next to the mold unit for removing a molded product from the mold. The molded product is initially coolied in the mold cavity then again cooled after removal from the mold unit. Plural chucks are advanced into and retreated from a region defined by the open molds, the chucks being a pair of blocks grasping the surface of the molded product, each block having a circulating path through which a heating medium is passed to cool the grasping surface. The injection-molding apparatus produces articles having high dimensional accuracy, for example, electronic parts such as a magnet roll or the like.
摘要:
In a process for preparing pre-expanded particles of a thermoplastic resin which comprises releasing into a low pressure zone an aqueous dispersion of thermoplastic resin particles containing a volatile blowing agent, the dispersion being maintained at an elevated temperature under pressure in a pressure vessel, the improvement which comprises releasing the dispersion through an orifice having a ratio of the length to the average diameter of 4 to 100. According to the present invention, the pre-expanded particles having cells which are uniform in diameter and have an average dimeter of not less than 200 .mu.m can be obtained, and therefore the articles molded in a mold from the pre-expanded particles are small in the shrinkage and strain, are excellent in the appearance, and are increased in the productivity. Accordingly, the molded articles are utilizable for use of shock absorbing, wrapping materials or structural material such as impact-absorbing materials for cars which requires excellent dimensional precision and heat insulating building materials.
摘要:
The present invention provides polypropylene resin pre-expanded beads formed by shrinking polypropylene resin pre-expanded beads originally having a bulk density of not higher than 0.0930 g/cc to give then a bulk volume ratio of 10-75% at the normal temperature and the normal pressure, a manufacturing method thereof and an expansion-molding method with the aforementioned pre-expanded beads. According to this invention, it is possible to greatly reduce storing and transporting costs per unit weight of pre-expanded beads.
摘要:
A pre-expanded particle of a propylene resin having two melting temperatures as determined by DSC, the heat of fusion for the peak based on the higher melting temperature being 0.5 to 2.3 cal/g. By using the pre-expanded particles of the propylene resin of the invention, foamed articles having excellent surface appearance, small dimentional shrinkage can be easily obtained without the procedure for giving the internal pressure.
摘要:
A process and apparatus for preparing pre-expanded particles of a thermoplastic resin which comprises; heating under an elevated pressure an aqueous dispersion comprising thermoplastic resin particles containing a volatile foaming agent and an aqueous medium in a pressure vessel; releasing the dispersion from the pressure vessel into a space within a sealed low-pressure vessel wherein the pressure is lower than that in the pressure vessel, whereby expanding the thermoplastic resin particles to give pre-expanded particles; and simultaneously recovering the foaming agent volatilized from the thermoplastic resin particles by discharging the foaming agent out of the space in the low-pressure vessel with controlling the pressure in the low-pressure vessel to substantially a given pressure. According to the process, the release of the volatile foaming agent into the air is prevented.