JPS6134465B1 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to glass fiber reinforced polyethylene terephthalate resin compositions. In general, molded products made from crystalline polymers such as polyethylene terephthalate naturally have a limit to the degree of crystallinity that they can achieve even if they are molded and crystallized using normal molding methods, and the degree of crystallinity that can be achieved is naturally limited, and the crystallinity is amorphous near the second-order transition temperature of the amorphous portion. As the region transitions from a resin state to a rubber state, rigidity is rapidly lost. At this time, the presence of a highly rigid fibrous reinforcing material in the polymer base material significantly improves the rigidity of the crystalline polymer from the secondary transition temperature to the melting point of the crystal, thereby increasing the heat resistance temperature under a constant load. It is well known that the heat deformation temperature (heat distortion temperature) can be significantly improved. Generally speaking, according to the theory of reinforcement using fibrous substances, it is said that the longer the length of the reinforcing material is, the greater the effect will be. Various ideas have been reported. For example, Special Publication No. 457, Special Publication No. 44-
Publication No. 7542 and the like contain descriptions of glass fiber-reinforced polyethylene terephthalate molding materials, and indicate that the glass fibers present therein must have a length of 0.4 mm or more. Furthermore, British Patent No. 950656 and British Patent No. 988563,
It is generally stated that glass fibers with a length of 1 to 10 mm are required to improve mechanical properties by adding glass fibers to thermoplastic resins. However, when molded products are manufactured from these known glass fiber-reinforced polyethylene terephthalate resin compositions by normal injection molding methods, significant anisotropy occurs in mechanical properties, mold shrinkage rate, etc. The appearance, such as surface gloss and texture, deteriorates. The present inventors have conducted various studies to improve these drawbacks, and have found that in order to obtain a molded product with excellent strength, low anisotropy, and a good gloss appearance, it is necessary to incorporate glass fibers in the molding material. The present invention was arrived at by discovering that distribution plays a major role. The present invention uses polyethylene terephthalate 90-50
% by weight and 10 to 50% by weight of glass fibers with a length of 0.05 mm or more, of which the length is 0.4 mm.
A glass fiber-reinforced polyethylene terephthalate resin composition for molding, characterized in that the amount of the above is from about 1.6% by weight to less than 10% by weight based on the total composition. Reinforced polyethylene terephthalate molding materials with different glass fiber distributions and different glass fiber contents were mixed and shaped in various kneading states, and samples with a thickness of 3.2 mm were prepared using a conventional injection molding method. However, when the die-stud impact strength was measured in directions parallel and perpendicular to the direction of resin flow, it was surprisingly found that specific changes in the properties of the molded product appeared when the glass fiber content exceeded a certain limit length. It was done. In other words, regarding the relationship between the content of glass fibers with a length of 0.4 mm or more in the molding material and the die-stud impact strength of the molded product, as shown in Figure 1, the impact strength in the direction parallel to the flow is
The value increases slightly as the content of glass fibers with a length of 0.4 mm or more increases, but as shown in Figure 2, the value in the direction perpendicular to the flow is 10% by weight when the content of glass fibers with a length of 0.4 mm or more increases. When it exceeds , it drops rapidly.
Furthermore, in order to clarify what meaning this has on the properties of the molded product, we express the anisotropy of the molded product in terms of the strength ratio in the parallel direction and the perpendicular direction. It is recognized that when glass fibers with a length of 10% or more by weight are present in the molding material, the anisotropy increases rapidly. Surprisingly, these relationships hold almost independently of the total glass fiber content in the molding material; for example, even if the content of long fibers is increased, the strength in the parallel direction improves, but the strength in the perpendicular direction decreases. The anisotropy shown in FIG. 3 remains on the extension of the curve shown in FIG. The disadvantages of large molded parts are further exacerbated. Furthermore, molded products made from polyethylene terephthalate resin compositions in which the content of glass fibers of 0.4 mm or more is approximately 1.6% to 10% by weight or less have not only low anisotropy in mechanical strength but also low mold shrinkage and linear The anisotropy of the expansion coefficient was also small, and favorable performances such as improved toughness and improved appearance gloss were also observed. In addition, molding materials containing short glass fibers of 0.4 mm or less are less likely to wear out molding machines and molds during molding than molding materials containing equal weight of long glass fibers. There is also. When the content of glass fibers is less than 10% by weight, the reinforcing effect is small regardless of their length, and too fine glass fibers, such as glass powder, which is at its extreme, have only a mere filling effect. For the purposes of the invention at least 0.05 mm, preferably
Preferably, the total composition contains at least 10% by weight of glass fibers with a length of 0.1 mm or more;
It is preferable that the number of glass fibers having a length of mm or less is as small as possible. If the glass fiber content exceeds 50% by weight, fluidity during molding decreases, which is not preferable. There is no limit to the length of glass fibers of 0.4 mm or more as long as it does not interfere with molding, but generally depending on the shape of the composition, for example, the pellet length,
Limited to about mm or less. Further, as for the thickness of the glass fiber, a thinner one is preferable because a shorter limit length is expected, but a glass fiber of 20 μm or less can be used effectively. Furthermore, as is generally known, it is preferable that the glass fiber be subjected to a surface treatment to obtain an effective reinforcing effect. Therefore, the composition range of the composition of the present invention is determined by the maximum content _of glass fibers with a length exceeding 0.4 mm based on the total glass fibers in the composition. The ratio Y of glass fibers with a diameter of 0.4 mm or more is determined by the curve Y _n
This is an area indicated by the range _ax <1000/X. The compositions of the present invention are prepared by kneading the raw materials using conventional molten polymer kneading equipment. In the present invention, polyethylene terephthalate includes, for example, a polyester produced by a polycondensation reaction of ethylene glycol and terephthalic acid, a copolyester in which a portion of terephthalic acid is replaced with isophthalic acid or other dibasic acid, and a polyester produced by a polycondensation reaction of ethylene glycol and terephthalic acid. Copolyesters in which a portion is diethylene glycol or other glycols, or mixtures of two or more of these are used. In addition, the intrinsic viscosity at 25° C. in a tetrachloroethane-phenol mixed solvent is at least 0.4, preferably 0.5 or more, except in special cases. The composition of the present invention may optionally contain heat and light stabilizers, various dyes and pigments, organic or inorganic fillers containing high polymers other than glass fibers, organic or inorganic fillers, etc. Additives such as crystal nucleating agents and flame retardants can be added. The composition of the present invention can be molded into compositions having various shapes by conventional methods. When using the injection molding method, mold temperatures can range from room temperature to 200℃, and molded products, including injection molded products,
Heat treatment in the temperature range of 100-200℃, surface painting,
Post-processing such as surface metallization and surface dyeing can be performed. In the following examples, % means weight %. Since polyethylene terephthalate resin is easily hydrolyzed due to moisture absorption, the polyethylene terephthalate used was vacuum dried at 160° C. for 4 hours so that the moisture content was 0.01% or less before molding. Examples 1 to 10 Glass fiber-reinforced polyethylene terephthalate resins in which the content of glass fibers with a length of 0.4 mm or more is 10% or less based on the total composition, and the total glass fiber content is 15, 20, 30, and 40%, respectively. From the composition,
Tables 1 to 4 show the physical property values of molded products obtained by the usual injection molding method under the following molding conditions as Examples 1 to 10, respectively. Injection molding conditions Injection molding machine: 50Z, 36φ screw, SJ-35A
(Manufactured by Meiki Seisakusho) Cylinder temperature: 180℃ for front, middle and rear Injection pressure: Shot shot pressure + 100Kg/cm ² Injection speed: 3 seconds Screw back pressure: 80Kg/cm ² Screw rotation speed: 60rpm Molding cycle: Holding pressure 10 seconds, cooling 30 seconds, other 20 seconds
Seconds Mold temperature: 150℃ Molded product shape: 3.2mm thick No. 1 dumbbell, 3.2mm thick thermally deformed specimen and 6.4mm thick thermally deformed specimen For comparison, 10% glass fiber with a length of 0.4mm or more
More and total glass fiber content 15, 20, 30
Comparative Examples 1, 2, and 3 are the results of manufacturing molded products from glass fiber-reinforced polyethylene terephthalate resin compositions of 40% and 40%, and examining their physical properties.
and 4 are shown in Tables 1 to 4. The symbol MF in each table is a milled fiber adjusted to have 50% glass fiber with a length of 0.4 mm or more, CS is a tip strand type glass fiber with a length of 3 mm or 6 mm, and the numbers are for both. Indicates the mixing ratio. Regarding the amount of glass fibers with a length of 0.4 mm or more (GF amount), take a 20x enlarged photograph of the glass fibers extracted from the pellets using a universal projector, and
The weight ratio of glass fibers with a length of 0.4 mm or more was determined from the weight distribution curve of the 1000 glass fibers, and the ratio to the total composition was calculated from this and the content of glass fibers (counting method). For the total glass fiber content (GF content), 0.57 to 0.7 g of the pellets were dissolved in 100 ml of an equal weight mixed solvent of tetrachloroethane and phenol, and a 0.5% solution of polyester was prepared by passing through the glass fibers. The GF content was determined by measuring the weight of the glass fibers (gravimetric method), and the GF content was 0.5 of the polyester.
% solution, the intrinsic viscosity [η] was determined from the following equation by single point measurement at 25°C. [η]=η _sp/c [1/1+0.28η _sp ] Appearance was determined with the naked eye, with symbol A indicating good gloss and texture, B indicating good gloss, and C indicating slightly poor gloss.
Dine stud impact strength is width 12.7mm x length 127mm
× From a 3.2 mm thick molded product, cut out 8 specimens from the direction parallel to the flow and from the direction perpendicular to the flow.
Dine stud impact strength was measured according to the method of DIN53453. Anisotropy was expressed as the ratio (parallel direction/perpendicular direction). The bending stress was determined by the method of ASTMD-790, and the elastic modulus was determined from the initial slope of the bending stress-strain curve, and the toughness of the molded product was determined from the area up to fracture. The heat distortion temperature is determined by the method of ASTMD-648.
Using a specimen of width 12.7 mm x length 127 mm x thickness 6.4 mm,
It was determined using a maximum stress of 18.6Kg/ ^cm2 .

【table】

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[Table] These results show that the composition of the present invention has a superior appearance, less anisotropy, higher toughness and bending strength, and higher rigidity and heat resistance than conventionally known glass fiber reinforced polyethylene terephthalate. It can be seen that this is a well-balanced molding material. Examples 11-12 15 parts of short glass fibers with a thickness of 13 μm and a length of 6 mm were mixed in a tetrachloroethane-phenol mixed solvent at 25°C.
85 parts of polyethylene terephthalate with an intrinsic viscosity of 1.20 was mixed in a V-type blender for 20 minutes, and then the mixture was placed in a regular 40φ single screw extruder (L/D = 24, compression ratio 2.3, rapid compression type screw). and molded into pellets at a cylinder temperature of 270°C. The load of the 200V-5KW motor required for extrusion was 8A. Comparative Example 5 was prepared by molding a mixture having the same composition at a cylinder temperature of 300°C. In this case, the load on the motor required for extrusion was clearly small, about 6A. Using 30 parts of short glass fibers with a thickness of 9μ and a length of 3 mm and 70 parts of polyethylene terephthalate with an intrinsic viscosity of 0.85, the cylinder temperature was adjusted in the same manner as in Example 11.
Example 12 was formed into pellets at 280°C. Comparative Example 6 was prepared by molding a mixture having the same composition at a cylinder temperature of 300°C. The intrinsic viscosity of each pellet obtained, the glass fiber content, the proportion of glass fibers with a length of 0.4 mm or more present in the glass fibers in the pellet, and the proportion of glass fibers with a length of 0.4 mm or more in the total composition. are shown in Table 5.

[Table] Example 13 30 parts of short glass fibers with a thickness of 9μ and a length of 3mm were mixed with 70 parts of polyethylene terephthalate with an intrinsic viscosity of 0.65, and a 40φ single-screw extruder equipped with a dullage having a kneading effect in the measuring section was used. It was molded into pellets at a cylinder temperature of 280°C. For comparison, the same mixture was molded using an ordinary single screw at a cylinder temperature of 280°C (Comparative Example 7). Its physical properties are shown in Table 6.

【table】

[Table] Example 14 A mixture of 40 parts of glass fiber with a thickness of 9 μm and a length of 3 mm and 60 parts of polyethylene terephthalate with an intrinsic viscosity of 0.58 was molded using a co-rotating twin screw extruder at a cylinder temperature of 280°C. . For comparison, the same mixture was molded using a conventional single screw at the same cylinder temperature of 280°C (Comparative Example 8). Its physical properties are shown in Table 7.

[Table] This result shows that even when low-molecular-weight polyethylene terephthalate with a low intrinsic viscosity is used, glass fibers will be cut if an extruder with shearing force is used, and the glass fiber content of 0.4 mm or more in the composition will be reduced by 10%.
% or less. Examples 15-18 50% glass fiber with a thickness of 9μ and a length of 0.4mm or more
Powder-free milled fiber (MF) prepared to contain powder-free milled fiber (MF) and chopped strand-type short glass fiber (CS) with the same thickness and length of 3 mm,
They were mixed at a ratio of 60/40 and 40/60, respectively. 20 parts of this glass fiber mixture was mixed with 80 parts of polyethylene terephthalate having an intrinsic viscosity of 1.20 and formed into pellets using a single screw extruder at a cylinder temperature of 270°C (Example 15 and Example 16). For comparison, only tipped strand type short glass fibers with a length of 3 mm were used and molded at a cylinder temperature of 300°C (Comparative Example 9). Also, the same MF used in Examples 15 and 16 above
and CS, and set the ratios to 60/40 and 50/, respectively.
Mixed at 50. 20 parts of this glass fiber mixture was mixed with 80 parts of polyethylene terephthalate with an intrinsic viscosity of 0.62, and the cylinder temperature was 280°C using a single screw extruder.
(Example 17 and
18). Only CS is used for comparison, others are examples
It was molded in the same manner as 17 and 18 (Comparative Example 10). The test results are summarized in Table 8.

[Table] From this result, in the mixture before molding, the length
If the proportion of glass fibers larger than 0.4 mm is 16% or less, molding using a single-screw extruder will cut long glass fibers regardless of the intrinsic viscosity of the resin, making it possible to
It can be seen that those with a diameter of 0.4 mm or more are less than 10%. Example 19 and Comparative Examples 11 to 16 Injection molded products were obtained in the same manner as in Examples 1 to 10, with the glass fiber loading amounts being 15% by weight and 30% by weight. Table 9 shows the physical properties of the molded product obtained.

[Table] From these results, molded products with a content of glass fibers of 0.4 mm or more of 0% or less than about 1.6% have good appearance and anisotropy, but have good bending strength, bending modulus, and thermal deformation. Molded products with poor physical property values such as temperature, and containing 10% or more have poor appearance and large anisotropy, as shown in Comparative Examples 1 to 4, and are not suitable for applications that require uniform strength.

[Brief explanation of the drawing]

Figures 1 and 2 show a length of 0.4 in the resin composition.
A graph showing the relationship between the glass fiber content of mm or more and the die-stud impact strength in directions parallel and perpendicular to the flow of the molded product. Figure 3 is a graph showing its anisotropy. Figure 4 is a graph showing the anisotropy of the resin composition. 2 is a graph showing the relationship between the glass fiber content and the proportion of glass fibers with a length of 0.4 mm or more.

Claims (1)

[Claims] 1 90 to 50% by weight of polyethylene terephthalate and glass fiber with a length of 0.05 mm or more with a length of 0.4 mm
About 1.6% by weight of the total composition
A glass fiber reinforced polyethylene terephthalate resin composition for molding, characterized in that it contains less than 10% by weight.