JPH0347711A - Structural body of fiber-reinforced thermoplastic resin pellet - Google Patents

Abstract

PURPOSE:To obtain a structural body of a fiber-reinforced thermoplastic resin pellet which can provide an extrusion-molded and injection-molded product superior in surface smoothness or mechanical physical properties, by a method wherein a fiber-reinforced thermoplastic resin sheet, which is comprised of specific thermoplastic resin and a fiber for nonconnection reinforcement and manufactured with a paper making method, is pelletized into a fixed form. CONSTITUTION:A fiber-reinforced sheet, which is comprised of 30-80wt.% thermoplastic resin and 70-20wt.% fiber for nonconnection reinforcement and manufactured with a paper making method, is pelletized into a fixed form. A fiber- reinforced thermoplastic resin sheet is manufactured, for example, of a thermoplastic resin fiber and a fiber for reinforcement with a manufacture of dry type nonwoven fabric, in a paper making technique to be used for manufacturing of a structural body of a fiber-reinforced thermoplastic resin pellet. Then along with melting of a resin fiber by making use of a hot press the resin fiber is integrated with a reinforcing fiber and a pellet structural body in a fixed form is manufactured by processing the sheet with an on-line or off-line hot or cold pelletizer.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fiber-reinforced thermoplastic resin pellet structure that can provide extrusion molded products, injection molded products, etc. with excellent surface smoothness and mechanical properties. It is.

[Prior art]

Various studies have been conducted on fiber-reinforced thermoplastic resin pellet structures with excellent mechanical properties consisting of thermoplastic resin and reinforcing fibers. "A pellet product made by kneading glass fibers with an extruder or the like to form a strand, and then cutting the strand."
Japanese Patent Publication No. 63-37694, Japanese Patent Publication No. 63-2527
No. 24, U.S. Pat. For example, there is a pellet structure j made by the pultrusion method (pultrusion molding method) in which the length is cut.

[Problem to be solved by the invention]

However, in these fiber-reinforced thermoplastic resin pellet structures, the reinforcing fibers are in the form of highly focused chopped strands or rovings, and the reinforcing fibers are uniformly dispersed in the resin, and the molten resin and reinforcing fibers are in the form of chopped strands or rovings. Since there are problems with uniform wettability with fibers, it is difficult to obtain molded products with uniform fiber distribution, and the surface smoothness is still insufficient and unsatisfactory.

Furthermore, in pellet structures obtained by kneading using an extruder, the fibers are often cut during the kneading process, and the mechanical properties of molded articles obtained using the pellets are poor.

[Means to solve problems]

In view of these circumstances, the present inventors have made extensive studies and found that a fiber-reinforced thermoplastic resin pellet structure is obtained by pelletizing a fiber-reinforced thermoplastic resin sheet made by a papermaking method into a predetermined shape. The present invention was completed by discovering scales that provide extrusion molded products and injection molded products with excellent surface smoothness and mechanical properties.

That is, the present invention comprises 30 to 80% by weight of thermoplastic resin,
A fiber-reinforced thermoplastic resin pellet structure is provided by pelletizing a fiber-reinforced resin sheet made by a paper-making method into a predetermined shape and containing 70 to 20% by weight of non-contiguous reinforcing fibers.

Thermoplastic resins used in the present invention include polyolefins such as polyethylene and polypropylene, polystyrene, rubber-reinforced polystyrene, acrylonitrile-styrene copolymers,
Styrene resins such as ABS resins, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon 6, nylon 66 and nylon 46, polyether resins such as polyphenylene ether and modified polyphenylene ether, polyoxymethylene, polycarbonate, Super heat-resistant resins such as polyarylate, polyphenylene sulfide, polysulfone, polyether sulfone, polyether ether ketone, polyether amide, blends of polycarbonate/polybutylene terephthalate, polycarbonate/ABS, polyphenylene ether/polybutylene terephthalate, polyphenylene ether/polyamide, etc. Examples include resin.

Basically, any thermoplastic resin can be used in the present invention, but crystalline thermoplastic resins, especially general-purpose thermoplastic resins, are good because they have a remarkable fiber-reinforcing effect, and they are inexpensive resin materials. In this case, it is preferable to use a powder or granule in the resin polymerization stage.

Preferably, the thermoplastic resin used in the present invention includes: polyolefins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins such as nylon 6, nylon 66, and nylon 46; polyphenylene ether, modified polyphenylene ether, etc. Polyether resin: polyoxymethylene, polycarbonate, polyphenylene sulfide, or a blend resin of these resins.

The reinforcing fibers used in the present invention may be of any type as long as they have a tensile modulus higher than the tensile modulus of the thermoplastic resin used in the present invention, such as inorganic fibers such as glass fibers, carbon fibers, ceramic fibers, and mineral fibers. Fibers, metal fibers such as stainless steel and brass, ultra-high molecular weight polyethylene fibers, polyoxymethylene fibers, polyvinyl alcohol fibers, liquid crystalline aromatic polyester fibers, polyethylene terephthalate fibers, poly-p-phenylene terephthalamide fibers, poly-m-phenylene Examples include aramid fibers such as isophthalamide fibers, organic fibers such as polyphenylene benzothiazole fibers, polyacrylonitrile fibers, and cellulose fibers.

The reinforcing fibers used in the present invention are selected in consideration of the mechanical properties and heat resistance required for the pellet structure of the present invention, the combination with the thermoplastic resin constituting the pellet structure, etc. Inorganic fibers such as glass fibers, carbon fibers, ceramic fibers, mineral fibers, metal fibers such as stainless steel and brass, liquid crystal aromatic polyester fibers, poly p-phenylene terephthalamide m fibers, poly-m-phenylene isophthalamide fibers, polyphenylene benzo fibers Thiazole fibers and the like are preferred.

The diameter of the reinforcing fibers is 3 to 20 μm, but if it is less than 3 μm, it is difficult to disperse the fibers in the process of making pellets.
When the length exceeds 20 μ-, it is undesirable because it is easy to break. The length of the reinforcing fibers is 3 to 20 mm. If the length of most of the reinforcing fibers is less than 3 mm, no fiber reinforcing effect is observed in the molded product, or , 20III11 is meaningless since it exceeds the maximum length of the pellet.

The amount of reinforcing fibers is between 20 and 70% by weight, preferably 30% by weight.
If the content is less than 20% by weight, no significant effect of reinforcing the fibers will be observed, and if it exceeds 70% by weight, the molded product such as an extrusion molded product will become brittle, which is not preferable.

The unconnected reinforcing fibers referred to in the present invention refer to fibers having a predetermined length (3 to 20 min) in a thermoplastic resin that are not present in a bundle, but are substantially unraveled. More preferably, the fibers are present in a state in which the fibers are substantially separated one by one, but the fibers may be present in a state in which the fibers are at least partially entangled.

The shape of the fiber-reinforced thermoplastic resin pellet structure is generally a columnar shape with a circular or elliptical cross section, or a so-called columnar shape with a triangular, rectangular, or polygonal cross section, but if necessary, it may have a plurality of cylinders etc. It may have a shape with combined openings, but its equivalent sphere equivalent diameter is 3 to 8 mm, preferably 4 to 6III+11, and its length is 3 to 20III, preferably 5 to 10+ nm.

In addition, the equivalent volume sphere diameter as used in the present invention refers to the diameter of a sphere when the volume of the pellet structure is converted to the volume of the sphere.

When the equivalent sphere diameter and its length, which are factors that determine the size of the pellet structure, are outside the above range, when melting and kneading the structure using an extruder, injection molding machine, etc.,
Depending on the conditions, pellet clogging or discharge fluctuations may occur in the screw part, and especially when the equal volume sphere equivalent diameter and length are both large, the molding special reinforcing fibers tend to break easily. It is desirable to select melting and kneading conditions.

The pellet structure of the present invention has mechanical properties and/or
Various fillers can be added for the purpose of improving surface smoothness and the like.

Examples of fillers include calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum silicate, talc, wollastonite, silicic acid, calcium silicate, mica, glass balloons, quartz balloons, graphite, Inorganic powders such as boron, alumina, silicon carbide, boron carbide, boria, boron nitride, silicon nitride, silica, beryllium, beryllium oxide, aluminum nitride, and surface-treated products of these powders, asbestos, potassium titanate, carbon, graphite , boron, alumina, silicon carbide, boron carbide, boria, boron nitride, quartz, silica, inorganic whiskers such as beryllium, microcellulose, thermosetting resin powder, aramid bulbs, and the like. Two or more types of these fillers may be mixed.

Furthermore, for the purpose of improving mechanical properties, a necessary amount of a thermoplastic resin to which a functional group has been introduced by maleation treatment or the like to impart adhesiveness may be blended.

Furthermore, as another means of improving mechanical properties, a coupling agent such as silane may be used during the pellet molding process.

Mechanical properties are affected by the degree of orientation of the reinforcing fibers in the molding pellet, and uniaxially oriented pellets have better mechanical properties than randomly oriented pellets.

In order to impart surface smoothness to the molded article, reinforcing fibers shorter than the main reinforcing fibers may be used in combination within a range that does not impair mechanical properties.

The fiber-reinforced thermoplastic resin pellet structure of the present invention includes flame retardants, heat stabilizers, antioxidants, ultraviolet absorbers (inhibitors),
Various stabilizers such as lubricants and colorants can be added to the extent that they do not impair the surface smoothness and mechanical properties of the molded product using the pellet structure.

The papermaking technology used to manufacture the fiber-reinforced thermoplastic resin pellet structure of the present invention includes, for example, manufacturing a fiber-reinforced thermoplastic resin sheet from thermoplastic resin fibers and reinforcing fibers by a dry nonwoven fabric manufacturing method, Next, there is a method of manufacturing a pellet structure of a predetermined shape by melting the resin fibers using a hot press and applying the sheet integrated with reinforcing fibers to a hot or cold pelletizer online or offline.

Also, JP-A-57-28135, JP-A-58-5
As described in Japanese Patent Application No. 9224, etc., a fiber-reinforced thermoplastic resin sheet is manufactured from a powdered thermoplastic resin and reinforcing fibers by a wet-laid nonwoven fabric manufacturing method, and then heated online or offline using a belt press or the like. There is a method of manufacturing a pellet structure of a predetermined shape by melting the resin using a press and applying a sheet formed by bonding and integrating reinforcing fibers to a hot or cold beletizer, either online or offline. Wet-processed nonwoven fabric manufacturing methods include horizontal fourdrinier (short 1i1) method and inclined fourdrinier (short mesh) method.
Examples include the cylinder type, cylinder type, suction type cylinder type (for example, rotoformer), and combinations thereof.

Regardless of which manufacturing method is adopted, for example, 0.5
When producing a sheet with a thickness of m or more, a plurality of original sheets are laminated and passed through a hot press.

When laminating sheets, it is possible to change the blending ratio of reinforcing fibers in the skin layer and core layer, or to use different thermoplastic resins in the skin layer and core layer.

In order to provide extrusion molded products, injection molded products, etc. with excellent surface smoothness and mechanical properties, the better the dispersibility of the reinforcing fibers in the fiber-reinforced thermoplastic resin pellet structure, the better.

In order to produce fiber-reinforced thermoplastic resin pellets with excellent dispersibility of reinforcing fibers, (1) completely remove the sizing agent used to increase the bulk density of reinforcing fibers;
For example, in the case of chopped strands of reinforcing fibers that have been hardened with a water-soluble sizing agent, the chopped strands are first immersed in a highly concentrated sizing agent removal solution, and then filtered through a deck or valveless filter. An example of this method is to dehydrate and concentrate the slurry using a high-speed mixer, thin-blade beater, etc., then dilute the concentrated and dehydrated chopped strand slurry with water, and then defibrate it using a high mixer, thin-blade beater, etc. , to select conditions that do not cause fiber cutting, reagglomeration, or entanglement.

What is even more important is (2) maintaining the defibrated reinforcing fibers and thermoplastic resin (usually powder) in a uniformly dispersed state until the web is formed. In the papermaking process, the slurry concentration is generally lowered in the later stage, but the concentration of papermaking aids such as dispersants and thickeners is preferably maintained at a constant concentration so as not to decrease; The slurry concentration at the time of formation should be kept as low as possible, and (1) measures should be taken to prevent reinforcing fibers from agglomerating or entangling in the slurry transport line, including pumps, piping, etc.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited thereto.

Example 1 (a) Polypropylene powder with an MFI of 14 and 3.0% by weight slurry water prepared by adding 0.2% by weight of an amine-type nonionic surfactant to the polypropylene;
(b) A reinforcing fiber made of glass fiber with a fiber diameter of 10 μm and a fiber length of 13 mm, and 0.15% by weight of a polyethylene glycol ester type dispersant based on the reinforcing fiber.
After preparing 1 and 0% by weight of reinforcing fiber slurry water, (a) and (b) were mixed in a ratio of 1=3 to obtain 50% by weight of polypropylene and 50% by weight of reinforcing strong fibers.
Create a 1.5% by weight slurry water consisting of
Next, this slurry water was diluted with water containing 0.03% by weight of a polyethylene glycol ester type dispersant to obtain a slurry concentration of 0.4% by weight, and then a web with a basis weight of 260 g was created using a hand sheet machine. did.

Note that the reinforcing fibers were defibrated in the following manner.

Add 10% by weight of glass fibers with a fiber diameter of 1Op and a fiber length of 13mm to water containing 0.5% by weight of a lauryl ether type penetrant (removal of sizing agent) to create a 10% by weight reinforcing fiber slurry water. Then, the slurry water is dehydrated and concentrated using a valveless filter to create a cake of reinforcing fibers containing about 50% by weight of water, and the cake is diluted with water to again contain 10% by weight of reinforcing fibers. The fiber slurry water was treated for a short time with a high mixer, and then further diluted with water to make the concentration of the slurry water 5% by weight, and then defibrated using a thin-blade beater.

Based on this slurry water, a 1.0% by weight reinforcing fiber slurry water containing 0.15% by weight of a polyethylene glycol ester type dispersant based on the reinforcing fibers was prepared. At this time, three types of webs with different textures were created by adjusting the degree of agitation in the sheet machine.

Next, 10 sheets of this web were laminated and dehydrated using a press, and then dried at 120'C for 1 hour, and then heated at a temperature of 200'C1 pressure of 10kg/ct using a sheet forming press.
It was heated for 16 minutes under the conditions of A, and then cooled for 20 minutes at a temperature of 15° C. and a pressure of 15 kg/c to produce a fiber-reinforced thermoplastic resin sheet with a thickness of 2 mm.

Hang this sheet on a cold sheet pelletizer,
A pellet structure of 6nuX 6nuX 2no++ (thickness) was made. Next, using this pellet structure,
120mm x 80mm x under the injection conditions shown in Table 1
3 m.

A molded plate of (thickness) was created.

The characteristics of the pellet structure used here, and the surface smoothness and mechanical properties of the injection molded plate are shown in Table 2.

A sheet and pellet structure were molded under exactly the same conditions as in Example 1, except that a blank space was added, and then an injection molded plate was created. The characteristics of the pellet structure used here, and the surface smoothness and mechanical properties of the injection molded plate are shown in Table 3.

Table 3 Example 3 In Example 2, when 10 webs were laminated and dehydrated using a press, 2 parts of the silane coupling agent was added by spraying based on the combined weight of the resin and glass fibers. The sheet and pellet structures were molded under the same conditions as in Example 1, except for the following conditions, and then an injection molded plate was created.

The characteristics of the pellet structure used for this, and the surface smoothness and mechanical properties of the injection molded plate are shown in Table M4. The reflection angle was 45 degrees and the width of the optical comb was 0.5 mm.

The surface smoothness of the injection molded plate is 9 to 12%, but the surface smoothness of the injection molded plate of Comparative Example 1, which will be described later, is 6%. The surface smoothness of the plate is improved by 50-100% compared to conventional plates.

Example 2 The polypropylene powder of MF114 of Example 1 was converted into MF1
MF16 adhesive polypropylene (trade name: ADMER) is 25 parts per 100 parts of polypropylene powder of MF14.

Example 4 The polypropylene powder of MF114 of Example 1 was converted into MF1
Except that 10 parts of silanized aluminum hydroxide was added to 100 parts of polypropylene powder of No. 14.
After molding the sheet and pellet structures under exactly the same conditions as in Example 1, an injection molded plate was created.

The characteristics of the pellet structure used here, and the surface smoothness and mechanical properties of the injection molded plate are shown in Table 5.

Table 5 Table Example 5 Sheet and pellet structures were produced under exactly the same conditions as in Example 1, except that the web was produced using a long paper machine instead of the hand sheet machine in Example 1. After molding, an injection molded plate was created.

Incidentally, MD/T of the tensile strength of the sheet after forming press
The D ratio was 2.7.

The properties of the pellet structure used here, the surface smoothness and mechanical properties of the injection molded plate are shown in Table 6.

Comparative Example 1 Comparative example 1 was carried out using a commercially available pellet structure of glass fiber reinforced polypropylene (glass fiber diameter 13 μm, same length 4.5 mm, blending amount (nominal) 30% by weight, product kneaded by an extruder). An injection molded plate was produced under exactly the same conditions as in Example 1. The properties of the pellet structure used here, and the surface smoothness and mechanical properties of the injection molded plate are shown in Table 7.

Comparative Example 2 Commercially available polypropylene and glass fibers made by the pultrusion method (fiber diameter 19μ■, fiber length 13II)
1ml, blending amount (nominal) 50% by weight), under the injection conditions shown in Table 8, 120mm
A molded plate of x 80 mm x 3 ttm (thickness) was created.

Table 8 The properties of the pellet structure used here, the surface smoothness and mechanical properties of the injection molded plate are as shown in Table 9.

〔Effect of the invention〕

As explained above, the fiber-reinforced thermoplastic resin pellet structure made by the papermaking method of the present invention can provide extrusion molded products, injection molded products, etc. with excellent surface smoothness and mechanical properties, so the surface It is useful as a product in fields where the balance between smoothness and mechanical properties is important, such as automobile parts, home appliance parts, and other parts that are exposed to the outside of industrial and consumer equipment, and its industrial use The value is high.

Claims (1)

[Claims] 1. Fiber-reinforced thermoplastic made by pelletizing a fiber-reinforced thermoplastic resin sheet made by a papermaking method into a predetermined shape, consisting of 30-80% by weight of thermoplastic resin and 70-20% by weight of non-contiguous reinforcing fibers. Resin pellet structure.