JPS6221608B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing glass fiber reinforced polyamide resin. Specifically, the present invention provides an intermediate material and a manufacturing method for making more effective use of the toughness of nylon and the rigidity of glass fiber in composite materials. It is already known that not only polyamides but also thermoplastic resins in general can be reinforced with glass fibers, and various methods have been adopted. The most common method is to use thermoplastic resin pellets or powder and approximately 3-6 mm
In this method, glass fiber bundles cut into glass fibers are mixed at a predetermined ratio and fed to an extruder for melt kneading. Although this method is widely practiced because it does not require any special steps, it has the following problems. Separation of resin and glass fiber occurs in the hopper of the extruder, making it difficult to obtain a product with a uniform composition. When blending pellets and glass fiber bundles, the glass fiber bundles become single fibers and bulky, making it difficult to uniformly supply them to the extruder, especially when the glass fiber bundles are highly filled. In order to solve the above problem, if the glass fiber binding agent is strengthened or the length of the cut is increased, uniform dispersion into the resin cannot be achieved, and the expected physical properties cannot be obtained. Binding agents used to improve kneading operability impede adhesion between glass fibers and resin and reduce physical properties. The glass fibers are crushed and the expected physical properties cannot be obtained. Equipment wear is significant, running costs are high, and stable physical properties are difficult to obtain. In order to solve these problems, resin pellets and glass fibers must be simultaneously fed in fixed amounts to the hopper. A special twist is made to the extruder supply section. Two or more supply ports are provided in the direction of movement of the extruder cylinder, and glass fiber is supplied after melting the resin. Two extruders are connected, and the resin and glass fibers melted in the first extruder are supplied to the second extruder for kneading and extrusion. There are the following methods, but all of them are complicated in terms of equipment and do not necessarily produce satisfactory effects. There is also a method for producing glass fiber reinforced materials in which a crosshead is installed at the tip of an extruder, the glass fiber bundles are continuously passed through the molten resin, the resin is directly coated, and then the material is cut into pellets. High resin viscosity (usually 2000~
4000poise), it is difficult for the resin to penetrate into the glass fiber bundles, and the glass fiber bundles tend to remain during remelting and molding, and the adhesion between the glass fibers and resin is poor.
Performance is also not satisfactory. Furthermore, there is a method in which glass fiber is added in advance to the raw material monomer during resin polymerization, but it is easy to separate due to the difference in specific gravity, requires special equipment and ingenuity, and is not suitable for manufacturing a wide variety of materials in small quantities. is not a preferable method because it causes a lot of switching loss. In view of the above-mentioned current situation, the present inventors have conducted extensive research and discovered that master pellets with a high glass fiber content can be manufactured in advance using a solution of solvent-soluble polyamide, and We have found a way to easily obtain high-performance glass fiber-reinforced polyamide resin materials or directly molded products by diluting and melt-mixing them with base polyamide resins. In other words, the main component is master pellets for manufacturing glass fiber reinforced polyamide resin, which are made by cutting glass fiber bundles (rovings) fixed with solvent-soluble polyamide resin into approximately the same size. A glass fiber bundle is continuously impregnated with a solution of a solvent-soluble polyamide resin, the excess resin solution is removed through a squeeze bushing, the shape is maintained in a rod shape, and the solvent component is scattered under tension to firmly bind the fibers. A method for producing master pellets for producing glass fiber-reinforced polyamide resin, characterized in that the master pellets are then cut into particles with approximately the same size using a cutter. Glass fiber bundles fixed by solvent-soluble polyamide resin are finely cut to approximately the same size, and the master pellets are mixed with base polyamide resin pellets, and extrusion or injection molding is performed to obtain the desired glass fiber content. A method for producing a glass fiber-reinforced polyamide resin molding material or molded article. It is. Glass fiber-reinforced polyamide resin combines the toughness of polyamide resin with the rigidity of glass fiber, and exhibits excellent performance as a composite material, but its performance is significantly affected by the manufacturing method. It is something that will be done. An essential requirement for exhibiting the generally expected physical properties is that there are no bundles of glass fibers in the resin, and that they are uniformly dispersed. The glass fibers in the resin do not become fine powder and have a certain length. (For example, the ratio L/D of fiber length to single fiber diameter is preferably 10 or more.) The interface between the resin and the glass fiber is in close contact and adhesion. It is said that According to the method of the present invention, the glass fibers are immersed in a solvent-soluble polyamide resin solution and the resin solution is impregnated between the single fibers, so that the resin and the surface of the glass fibers are in close contact with each other. Moreover, since a coupling agent can be added to the resin liquid, even stronger adhesion can be obtained. Furthermore, solvent-soluble polyamides generally have a low melting point or softening point and are highly compatible with the base polyamide resin. softens and melts,
Because the glass fiber bundles are loosened and uniformly dispersed in the base polymer, harsh kneading is not required, and as a result, the glass fibers are less likely to become fine powder.
A constant fiber length is maintained. Furthermore, since the glass fibers are coated with resin in advance, there is less equipment wear in the supply section and compression section of the extruder during melt kneading. The glass fiber bundle used in the present invention is commercially available.
Glass roving for FRP is fine, and for FRTP blend kneading, it is better not to have a reinforced binder. It is preferable to use a grade that has enough cohesiveness to prevent single filament breakage when being pulled out from the roving cake, and is rather focused on a coupling agent treatment for interfacial adhesion. The solvent-soluble polyamide used in the present invention is a polyamide multi-component copolymer, such as 6/66/
6I, 6/66/610, 6/66/12, 6/66/PACM6
etc., which are water and lower alcohol soluble copolyamides. Water soluble copolyamides such as 6/66/6I/6SLPE can also be used. Here 6 is ε-
Caprolactam, 66 is a polycondensation component of hexamethylene diamine and adipic acid, 610 is a polycondensation component of hexamethylene diamine and sebacic acid, 6I is a polycondensation component of hexamethylene diamine and isophthalic acid,
12 is ω-laurolactam, PACM6 is bis(4-
6SIPE is a polycondensation component of methane (aminocyclohexyl) and adipic acid, and 6SIPE is a polycondensation product of mexamethylene diamine and 5
- Refers to the polycondensation component of sodium dimethyl sulfoisophthalate. The base polyamide resin used in the present invention is a polyamide resin whose main component is a homopolymer such as 6, 66, 610, 11, 12, MXDA-6, or a copolymer consisting of these monomers, and a nucleating agent is used. , various modifiers such as inorganic fillers, flame retardants, heat resistant agents, weathering agents, and antistatic agents, and/or coloring agents such as pigments and dyes. The melting point or softening point of the solvent-soluble polyamide for producing master pellets of the present invention is preferably lower than the melting point or softening point of the base polyamide resin, and if it is higher, good dispersion of glass fibers may occur during the mixing melt kneading process. is difficult to obtain. In the case of a base resin having a melting point of 200 to 260°C, good results can be obtained if a solvent-soluble polyamide of master pellet having a melting point of 180°C or lower is used. In the present invention, the solution of the solvent-soluble polyamide for producing master pellets is dissolved in a solvent such as water, lower alcohol, or a mixed solvent thereof in an amount of 20% by weight or more, and has a concentration of 0.5 to 50 poise at room temperature, more preferably 30% by weight or more. It is preferable to have a viscosity of ~10 poise; if the viscosity is too low, impregnation into the glass fiber bundle is good, but the cohesion after drying is insufficient, and if it is too high, impregnation will be poor, and the final composition will not have sufficient physical properties. I can't. Next, a process of introducing the glass fiber bundle into a resin liquid tank and impregnating it with resin liquid will be described. Diameter 7~
Glass fiber bundle (roving) consisting of 20μ single yarn
Untwist the fibers so that they are not twisted, introduce them into the resin liquid tank, and connect them to several bar guides (squeeze bars) on the premises.
After removing the excess resin liquid with a bar guide outside the tank if necessary, insert it into a squeeze bush with a hole of an appropriate diameter.
A final squeeze is performed or twice to retain the shape. The roving passes through a W-shaped path using a squeeze bar, but depending on the viscosity of the resin liquid and the line speed, extremely high tension may be required.
Adjust by the angle of the roving to the squeeze bar and the number of squeeze bars. If the tension is too high, single threads of the roving will break, and the apparent viscosity of the resin liquid in the tank will change, making stable and uniform production impossible, and the glass fibers will be concentrated in the center, making it difficult to maintain the shape. On the other hand, if the angle of the roving with respect to the bar is shallow and the number of squeeze bars is small, sufficient impregnation with the resin liquid cannot be obtained. In order to ensure sufficient impregnation, prevent damage to the roving, and improve shape retention, pass through at least two stages of squeeze bars with shallow angles, and final shape retention with a curvature on the inlet side and a length/diameter ratio of 3 or more. It is better to use Butsuyu. If the viscosity of the resin liquid is low and shape retention is difficult, the viscosity can be increased by adding inorganic fine powder, various synthetic resin powders, etc. to the resin liquid. Further, in order to strengthen the interfacial adhesion between the resin and the glass fibers, a soluble coupling agent can be dissolved in the resin solution. Conventionally, the surface of glass fibers has been treated with a coupling agent, but
This was not sufficient because it was necessary to take into account post-processing performance such as convergence. In addition, with methods such as post-processing the glass fiber bundles into pieces or dry blending when blending with resin pellets, it was difficult to achieve uniform treatment over the entire interface and the effect was not sufficient, but in the present invention, Since it is dissolved, uniform treatment is possible as long as there is sufficient impregnation, and an unprecedented interfacial adhesion effect can be achieved. The rod-shaped body that has been impregnated with resin liquid and maintained its shape is introduced into a drying process. Methods such as heat, hot air, infrared rays, and far infrared rays can be used for drying, but drying using high frequency heating is the most efficient. After the dried rod-shaped body is cooled, it is taken out and sent to a cutter. As a pulling device, a roller pulling device consisting of a drive roller and a nip roller system can be used, but if you use a caterpillar press type pulling device with a large contact area and low contact pressure, there will be less cracking after cutting into small pieces, and the apparent specific gravity will be reduced. It can be kept constant. Also, for the same reason, it is better to use a push cutter with a sharp blade rather than a shear cutter. The apparent specific gravity of the master pellets is preferably in the range of 0.5 to 1.5; if it is too small, it will be blended with the base resin and it will be difficult to stably supply the material during remelting and kneading, requiring special measures in the supply section. If it is too large, separation from the resin pellets will occur at the hopper, making uniform kneading difficult. Strictly speaking, it is ideal that the apparent specific gravity of the master pellet is the same as that of the base resin pellet, but it is necessary that the difference in the apparent specific gravity between the two be at least 0.5 or less. Further, the particle shape is preferably a cylindrical shape close to a spherical shape. The glass fiber content of the master pellets of the present invention is
60 to 95% by weight is preferred; if the glass fiber content is low, not only can it not be used as a master pellet for highly filled glass fiber reinforcement, but the resin content of the final composition will contain too much solvent-soluble polyamide component. However, it is difficult to obtain sufficient physical properties, and the cost is generally high. In addition, if the glass fiber content of the master pellet is too high, it will be difficult to obtain uniform dispersion of the glass fibers during the melt-kneading process of mixing with the base polyamide resin, and if the kneading is strengthened to obtain dispersion, the glass fibers will be crushed and insufficient. Physical properties cannot be obtained, equipment wear becomes severe, and the effect of the present invention is reduced. In order to fully exhibit the effects of the present invention in the production of glass fiber reinforced polyamide resin, the ratio of the solvent-soluble polyamide component to the final composition should be 1 to 30% by weight, preferably 3 to 15% by weight. It is better to make it . If the ratio of solvent-soluble polyamide is too low, good dispersion of glass fibers will not be obtained and the performance of the molded product, especially the impact resistance, will not be improved sufficiently; if it is too high, moldability will deteriorate and rigidity will decrease. descend. When mixing and remelting the master pellets and the base resin, it is necessary to dry the materials sufficiently, and in particular, it is necessary for the master pellets to have a volatilization loss of 0.2% by weight or less at the melting temperature. When the amount of volatilization of master pellets is large, air bubbles may form in the glass fiber reinforced polyamide resin.
Physically, the result is also unsatisfactory. Next, the present invention will be explained in more detail based on Examples, but the present invention is not limited thereto. Example 1 ε-caprolactam (6 monomers) 60 mol%,
Hexamethylene diammonium adipate (66
salt) 20 mol% and equimolar salt of hexamethylene diamine and dimethyl isophthalate (6I salt) 20 mol%
was placed in an autoclave with a small amount of water and stirred at 130°C for 2 hours under normal pressure in a nitrogen stream for initial condensation, and then continued heating at 270°C for 5 hours to form a polyamide with an intrinsic viscosity of 1.1 and a softening point of 155°C. A copolymer resin (6/66/6I) was obtained. This resin was pulverized and dissolved in methanol to obtain a stable resin solution with a concentration of 33% by weight and a viscosity of 7 poise at 20°C (as measured by a BH type viscometer manufactured by Tokyo Keiki Co., Ltd.). Next, three commercially available glass rovings with a single yarn diameter of 13 μm and a basis weight of 2.3 g/m were each introduced into the resin solution without twisting and unwinding, and the rovings were placed in a tank so that they passed through a W-shaped path. Impregnation and shape retention were carried out at a speed of 6 m/min by passing through a book bar guide through a squeeze bush having a hole of 2.5 mm in diameter and 10 mm in length with a curvature at the entrance. Although the roving was immersed in the resin solution for a distance of approximately 50 cm, the shape-retaining rod-like body became translucent, confirming that the resin solution was sufficiently impregnated between the single fibers. This rod-shaped material was introduced into a hot air drying furnace with a furnace length of 5 m and an atmospheric temperature set in stages from 80°C to 130°C, and after drying, it was cooled by blowing cold air, and then introduced into a caterpillar press type take-up machine with a contact length of 70 cm. The pellets were taken up and fed to a rotary cutter placed behind the pellets, and cut into approximately 3 mm length to produce master pellets. The resulting pellets had a glass content of 90% by weight, a volatilization loss at 255°C of 0.1%, and an apparent specific gravity of 0.68. This master pellet was mixed with nylon 6 resin pellets (diameter 2.2 mm, length 2.0 mm) having an intrinsic viscosity of 1.2.
Double diluted blend, cylinder diameter 65mm, L/
The material is put into the hopper of a D25 vented extruder, melt-extruded at a cylinder temperature of 270°C, and re-pelletized using a conventional method to obtain a glass fiber-reinforced polyamide resin molding material with a glass content of 30% by weight in a stable and highly efficient manner. Ta. The obtained molding material was molded into various test pieces using an injection molding machine with a cylinder diameter of 40 mm and a L/D of 15.
The physical properties were evaluated based on. In addition, a part of the molded product was dissolved in formic acid and photographed using a microscope to measure the average fiber length of the glass fibers in the molded product. Table 1 shows the results.
Shown below. Example 2 The master pellet obtained in Example 1 was diluted 3 times and blended with nylon 6 resin pellets with an intrinsic viscosity of 1.2, and a test piece was molded using the same molding machine as in Example 1 without re-pelletizing. , similarly evaluated. The results are shown in Table 1. Comparative Example A commercially available 6 mm cut roving (chopped strand) for FRTP and the same nylon 6 resin used in the example were mixed at a weight ratio of 3:7, and melt-extruded using the same extruder as in Example 1. A molding material with a glass fiber content of 30% by weight was made. A ribbon blender was used for mixing, but when blended for more than 10 minutes, the chopped strands turned into single fibers and became fluffy, making uniform blending difficult. In addition, during extrusion re-pelletization, the material was not stably fed into the extruder, causing irregularities and breakage of the strands. The same evaluation as in Examples 1 and 2 was also performed for the comparative example. Further, the molded pieces of Examples 1 and 2 and Comparative Example were decomposed with sulfuric acid and nitric acid, and trace amounts of iron contained in the resins were measured by atomic absorption spectrometry. Both results are also listed in Table 1.

【table】

[Table] As is clear from Table 1, the performance of the molded product using the master pellets of the present invention is significantly superior to that of the conventional method. It can be seen that the molding method also fully exhibits its effects. Of course, the chopped strands and nylon 6 used in the comparative example
It has been confirmed that when a blend of resin pellets is directly injection molded as a molding material, not only does it cause molding problems due to poor material penetration, but also that glass fiber bundles remain undispersed in the molded product.
No glass fiber reinforcement effect was observed. Also,
It can be seen that, judging from the iron content in each molded piece, the process according to the invention results in significantly less equipment wear. Example 3 Commercially available alcohol-soluble polyamide resin (Toray Industries, Inc.)
CM8000) was heated and dissolved in a mixed solvent of 9 parts methanol and 1 part water to obtain a polyamide resin liquid having a concentration of 20% by weight and a viscosity of 4 poise at 20°C. Using this resin liquid, pellets having a glass content of 93.5% by weight, a loss on heating at 270°C of 0.1%, and an apparent specific gravity of 0.71 were obtained through the same roving and the same steps as in Example 1. The obtained pellets were diluted 2.8 times and blended with nylon 66 resin pellets having an intrinsic viscosity of 1.3 as a master, and the mixed pellets were directly injection molded to produce molded pieces with a glass fiber content of 33%. The moldability was good, the surface of the molded piece was smooth, and no glass fiber bundles were observed and they were uniformly dispersed. Performance was measured based on ASTM in the same manner as in Example 1, and the average glass fiber length in the molded product was also measured. Table 2 shows the results.
Shown below.

[Table] Examples 4 to 7 Master pellets were produced under the same conditions as in Example 1, except for using the polyamide resin liquid used in Example 1 and using two rovings with a basis weight of 2.3 g/m. did. The resulting pellets have a glass content of 80
%, apparent specific gravity 0.65, heating loss 0.1% at 255℃
It was hot. Using these pellets as a master, they were diluted and blended with nylon 6 resin pellets having an intrinsic viscosity of 1.2, and test pieces with various glass contents were molded from the blend by direct injection molding, and their performance was evaluated in the same manner as in Example 1. The moldability and glass fiber dispersion were good at glass fiber contents of 15%, 30%, 45%, and 60%. The results are shown in Table 3.

【table】

【table】

Claims (1)

[Scope of Claims] 1. A master pellet for producing a glass fiber reinforced polyamide resin, which is obtained by cutting glass fiber bundles (rovings) fixed by a solvent-soluble polyamide resin into approximately the same size. 2. The master pellet according to claim 1, having a glass fiber content of 60 to 95% by weight. 3. The master pellet according to claim 1, having an apparent specific gravity of 0.5 to 1.5. 4 Polyamide resin copolymerized with one selected from the raw material monomers nylon 6, nylon 66, nylon 610, and nylon 12, and a resin solution in which 20% by weight or more is dissolved in a solvent system mainly consisting of methanol. A master pellet for producing a glass fiber-reinforced polyamide resin according to claim 1, wherein the master pellet is fixed with a solvent-soluble polyamide resin that can be stably obtained. 5 Claim 1 characterized in that it is a solvent-soluble polyamide resin with a softening point of 180°C or less
Master pellets as described in section. 6. A glass fiber bundle (glass roving) is continuously impregnated with a solution of a solvent-soluble polyamide resin, the excess resin solution is removed through a squeeze bushing, the shape is maintained in a rod shape, and the solvent component is scattered under tension. A method for producing master pellets for producing glass fiber-reinforced polyamide resin, which comprises binding fibers together and then cutting them finely into particles of approximately the same size using a cutter. 7. The method for producing master pellets according to claim 6, wherein the solvent-soluble polyamide solution is heated to have an apparent viscosity of 0.5 to 50 poise as measured by a single cylinder rotational viscometer. 8 After passing through at least two stages of squeezing equipment,
7. The method for producing master pellets according to claim 6, wherein the pellets are passed through a final shape-retaining bush having a length/diameter ratio of 3 or more and having a curvature on the inlet side. 9. The method for producing master pellets according to claim 6, which uses a resin solution in which a coupling agent soluble in the solvent of the resin solution is added. 10. The method for producing master pellets according to claim 6, characterized in that the glass fiber bundles (glass rovings) are fed to the resin impregnation step so as not to be twisted.