JPH0558017B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a granulated glass milled fiber used as a reinforcing material for thermosetting synthetic resins or thermoplastic synthetic resins. [Prior Art] Glass fibers used as reinforcing materials for thermosetting synthetic resins or thermoplastic synthetic resins include glass powder with a fiber length of 0.01 to 0.05 mm obtained by cutting and pulverizing glass fibers. However, although molded products using this glass powder as a reinforcing material have extremely smooth surfaces, they do not have sufficient strength. On the other hand, chopped glass fiber strands with a fiber length of about 3 mm have been widely used as reinforcing materials for thermosetting synthetic resins and thermoplastic synthetic resins, but as molded products become smaller and more sophisticated, The use of glass fibers with short fiber length has come to be desired, and in order to shorten the fiber length and obtain the desired strength of the molded product, the fiber length of the glass fiber is set to about 0.05 to 1.0 mm, and the aspect ratio, that is, the fiber length Attempts have been made to use glass milled fibers with a fiber diameter ratio of 10 to 50. In addition, when manufacturing a molded product by reinforcing thermoplastic synthetic resin with glass fiber by injection molding, pellets of thermoplastic synthetic resin and glass fiber are thoroughly kneaded in an extrusion molding machine and once pelletized, Furthermore, a two-step method is adopted in which the material is fed into an injection molding machine to obtain the desired molded product. [Problems to be Solved by the Invention] Glass milled fibers with a fiber length of 0.05 to 1.0 mm and an aspect ratio of 10 to 50 are used as reinforcing materials for thermosetting synthetic resins and thermoplastic synthetic resins. Therefore, if you try to use it as it is in a piled state, the fibers will cross and overlap each other and form a lump, making it impossible to automatically feed a fixed amount from a hopper or chute, making it difficult to apply it to continuous automatic molding. Moreover, mixing and uniform dispersion with the thermosetting synthetic resin or thermoplastic synthetic resin were often insufficient. In addition, when handling the glass fibers, undesirable phenomena such as glass fibers scattering, resulting in a decrease in yield, deterioration of the environment due to scattering, and accumulation on factory equipment, etc., are observed. In particular, it is difficult to further shorten the fiber length while retaining the chopped strand morphology, resulting in a state where chopped strands and filaments are mixed, such as the chopped strands separating into filaments. It has a negative effect on the strength and appearance of the product. In particular, it is desirable to simplify the two-step injection molding of thermoplastic synthetic resin reinforced with glass fibers to a one-step method from the viewpoint of productivity. The present invention has been made to solve these problems. [Means for solving the problems] The present invention has a fiber length of 0.05 to 1.0 mm and an aspect ratio of 10.
Glass milled fibers crushed and shredded into ~50 mm and separated into fibers are bonded and granulated in the presence of a trace amount of binder, bulk specific gravity 0.5~0.8 g/cm3, particle size
By making the granulated glass milled fiber 0.3 to 4.0 mm, it was possible to obtain a granulated glass milled fiber suitable as a reinforcing material for thermosetting synthetic resins and thermoplastic synthetic resins. The binder used here has a fiber length of 0.05 to 1.0
When glass milled fibers separated into fibers with a diameter of 10 mm and an aspect ratio of 10 to 50 are granulated, the intersection points of the fibers are temporarily bonded to the minimum amount necessary to maintain the granule shape, and the glass is bonded and bonded. When the milled fiber is mixed into the thermosetting synthetic resin or thermoplastic synthetic resin to be reinforced, it moves while rolling in a hopper or chute, and is supplied continuously or intermittently in a fixed amount. is mixed with the thermosetting synthetic resin or thermoplastic synthetic resin, and as the synthetic resin flows during molding, the particles lose their granularity and are uniformly distributed in the form of fibers. That is, water can be used as a bonding agent to bond separated glass milled fibers in a crosswise or parallel state to form granules, but water can be used to temporarily bond fibers together at their intersection points. , a thermoplastic resin binder such as polyvinyl acetate resin, polyacrylic ester resin, polyurethane resin, or a thermosetting resin binder such as polyester resin, epoxy resin, phenolic resin, melamine resin, etc. Alternatively, it is used in the form of a solvent solution, and the amount of the binder attached to the glass milled fiber is suitably about 0.4 to 0.6% by weight. The type of binder to be used is selected in consideration of the use of the granulated glass milled fiber, that is, the type of thermosetting synthetic resin or thermoplastic synthetic resin to be reinforced, and the molding method. When the thermosetting synthetic resin to be used is an unsaturated polyester resin, by using a polyester resin binder that is compatible with it, the impregnation of the unsaturated polyester resin into the granulated glass milled fiber is improved, and the binder Due to mutual compatibility between the resin and the synthetic resin, the granulated glass milled fibers lose their granularity as the resin flows during molding, and are uniformly distributed in the form of fibers in the molded product. In addition, when these binders are used in combination with known glass fiber surface treatment agents such as aminosilane, epoxysilane, and methacrylic silane, the bonding strength between the glass milled fiber and the thermosetting synthetic resin or thermoplastic synthetic resin to be strengthened can be improved. This is more preferable because it improves. The glass milled fiber provided with the binder is granulated by a granulating device. Various methods are known for granulating materials having a fiber form, but the granulated glass milled fiber of the present invention has a fiber length of 0.05 to 1.0 mm before granulation,
Since it is made of fibers having an aspect ratio of 10 to 50, it is necessary to take care to prevent the glass milled fibers from being further crushed during the granulation process. Therefore, the device used for granulation in the present invention is preferably a rolling type granulator, and in the present invention, granulation is performed using a rotating plate type granulator, which is a type of rolling type granulator. Ivy. The particle size distribution can be changed by variously changing the granulation conditions. Regarding the granulated glass milled fiber obtained in this way, we investigated the influence of the particle size and bulk specific gravity of the granulated product on the molding of synthetic resin, and found that the bulk specific gravity appears to gradually increase as the particle size increases, but the mobility of granulated glass milled fibers due to rolling and the dispersibility of fibers in synthetic resins are within the particle size range of 1.4 to 2.4 mm. It is known that granulated glass milled fibers with granulated glass milled fibers have a lower particle size than this, even if they have a larger or smaller particle size. This is thought to be the cause of defects such as partial insufficient kneading and non-dispersion when mixed with plastic synthetic resins. Therefore, considering the fluidity of the milled fiber during synthetic resin molding and the dispersibility of the fiber into the synthetic resin, the bulk specific gravity is 0.5.
Granulated glass milled fibers of ~0.8 g/cm3 and particle sizes of 0.3 to 4.0 mm were found to be most preferred. If the bulk specific gravity is outside the range of 0.5 to 0.8 g/cm3, whether the bulk specific gravity is large or small, the granulated glass milled fiber is likely to cause bridging in the hopper or chute, causing problems in process efficiency. be. In addition, for particles having a particle size outside the range of 0.3 to 4.0 mm, the fibers intersect and overlap without getting entangled, so they can be returned to the initial separation process into fibers and reused. [Example] A glass fiber filament with a diameter of 10 μm was
The assembled glass fiber strands are 3 mm in fiber length.
The chopped strands are cut, crushed, and shredded into lengths of 0.05 to 0.5 mm using a centrifugal crusher to obtain glass milled fibers separated into fibers with an aspect ratio of 10 to 50. Ta. Next, the glass milled fiber 3 that has undergone the treatment
Kg into a stirring device with high-speed rotating blades,
While stirring at a speed of 5000 revolutions per minute, a binder solution containing 0.1% by weight of epoxy silane and having a solid content of 0.7% by weight of polyvinyl acetate as a binder was added to a solution corresponding to 70% by weight of the glass milled fiber weight. The amount was applied at a rate of 200 g/min. Next, the glass milled fibers are granulated using a rotating plate granulator (trade name: Marmerizer, manufactured by Fuji Paudal Co., Ltd.), and heated and dried at a temperature of 125 to 135°C for about 5 hours to obtain granulated glass milled fibers. Got fiber. The amount of binder deposited on the granulated glass milled fiber was 0.5% by weight. The obtained granulated glass milled fiber was passed through a sieve and
The particles were classified into the six particle size ranges shown in the table, and the relationships among particle size distribution, particle size, bulk specific gravity, and mobility were measured. The results are shown in Table 2. The bulk specific gravity and mobility were measured by the following method.

[Table] ◎Bulk specific gravity: Granulated glass milled fiber 200g
was poured into a 100 ml measuring cylinder, and the volume was read and expressed in g/cm3. ◎Mobility: Granulated glass milled fiber 50g
, width 75mm, depth 30mm, length 200mm, slope angle 20
Place the thickness evenly in a square gutter with an amplitude of 1.5
It is expressed as the time it takes for half of the input amount, 25g, to move and fall from the gutter by rolling when vibration was applied at a frequency of 3000 times/min. Table 2 also shows the particle size of the granulated glass milled fibers and the number of undispersed glass milled fibers in the molded product. The undispersed number was measured by the following method.

〔Effect of the invention〕

As described in detail above, the granulated glass milled fiber of the present invention is obtained by crushing and shredding the glass milled fiber into fibers with a fiber length of 0.05 to 1.0 mm and an aspect ratio of 10 to 50, and separating the glass milled fibers into fibers with a bulk specific gravity of 0.5 to 1.0 mm.
In order to make it into granules with a particle size of 0.8g/cm3 and a particle size of 0.3 to 4.0mm,
Not only does it have good mobility, making it possible to automatically feed a fixed amount continuously or intermittently from a hopper or chute, but glass milled fibers can be granulated without entanglement and are separated into fibers. The small amount of binder used has compatibility with thermosetting synthetic resins and thermoplastic synthetic resins, so it is easy to knead with synthetic resins, and it is possible to mix from granulated glass milled fibers to milled fibers in synthetic resins. As a result, the molded products have excellent surface smoothness, no undispersed glass milled fibers, and excellent quality performance such as strength and other physical properties. A thermoplastic synthetic resin molded product could be obtained, and in particular, thermoplastic synthetic resin pellets and granulated glass fibers could be directly fed into an injection molding machine at the same time, thereby realizing molding in a one-step method. In addition, the individual fibers in the granulated glass milled fibers do not intertwine, but simply intersect,
Since they are overlapped and bonded with a small amount of binder, defective products can be recycled and used as milled fibers, and the yield of milled fibers into products is extremely high, and the economic effect is extremely large.

Claims (1)

[Claims] 1 Glass milled fibers are crushed and shredded into fibers with a fiber length of 0.05 to 1.0 mm and an aspect ratio of 10 to 50, separated into fibers, and bonded in the presence of a small amount of binder.
Granulated, bulk specific gravity 0.5~0.8g/cm3, particle size 0.3~
4.0mm granulated glass milled fiber.