JPS6017301B2 - Reinforced polyvinyl chloride resin molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyvinyl chloride resin molding material reinforced with gypsum needle crystal fibers and impact-improving rubber.

In recent years, research has been conducted in various fields aimed at improving mechanical strength, heat resistance, etc. by combining thermoplastic resins with fibrous reinforcing agents.

However, when a short fiber reinforcing agent is combined, although the tensile strength in the fiber direction is improved, there is a drawback that the impact strength, which is very important in terms of practical physical properties, is significantly reduced.

It is already known to mix and disperse rubber particles such as Amo and MSB in order to improve the impact resistance of molded products made of vinyl chloride resin.

In addition, it is reported in Japanese Patent Publication No. 15457/1983 that a composition with excellent impact resistance can be obtained by using surface-treated fine calcium carbonate in combination with ABS or MBS, but in this case, the tensile strength There is a significant decrease in or,
When combining fiber reinforcing materials such as short glass fibers with vinyl chloride resin, as shown in the comparative example, it is not possible to improve the impact strength simply by mixing and dispersing rubber such as ABS or MBS. This has the drawback that it requires a large amount of expensive rubber, which is not only economically unviable, but also involves a decrease in tensile strength. On the other hand, large amounts of calcium sulfite or gypsum are produced as byproducts from flue gas desulfurization.
The effective use of gypsum has been raised as an important issue, and its use as an inexpensive and fire-resistant filler is being considered in various fields. A method of using it as a filler has been proposed, but it has the drawback of decreasing impact strength.

As a result of intensive studies on gypsum fiber-filled vinyl chloride resin composite materials, the present inventors found that at least one kind of acicular crystal fibers of Q-hemihydrate gypsum, M-type anhydrous gypsum, or O-type anhydrous gypsum is contained in an amount of about 5% by weight. By containing desirably 5 to 7% by weight, more preferably 10 to 5% by weight, and 1 to 10% of impact-improving rubber, a molding material with a balance between tensile strength and impact strength can be obtained. This discovery led to the present invention.

According to the present invention, by using an inexpensive material called gypsum, the tensile strength is balanced, which has not been achieved with short fiber reinforced composite materials, and in addition, polyvinyl chloride is used, which does not cause wear on the molding machine or molding die, and has little dislocation. It is possible to provide a molding material based on resin.

Why is it that some glass fiber-filled vinyl chloride resin composites do not have improved impact strength even after adding impact-improving rubber?
It is not clear whether impact strength can be improved by using gypsum fibers and impact-improving rubber without reducing tensile strength too much.
The size of the gypsum fibers appears to play an important role. The acicular gypsum crystal fiber used in the present invention has a diameter of about 6 mm or less, but it is preferable to use one with a diameter of 2 mm or less. It may be any type of fiber or a mixture.

As shown in Example 1, gypsum fibers were produced by dispersing calcined gypsum in water, adding dihydrate gypsum powder if necessary to adjust the aqueous slurry concentration to 35% by weight or less, and producing hemihydrate gypsum needle crystals. While heating until fibers are obtained, the slurry is heated under pressure to form a slurry containing hemihydrate gypsum needle crystals, and dried in an oven to obtain Q-hemihydrate gypsum needle crystal fibers.

Furthermore, if necessary, it may be dried at 170 qo or more to obtain M-type anhydrous or sintered O-type anhydrous gypsum needle crystals.
Also, a mixture of these may be used, and if necessary, surface treatment may be performed to improve adhesion to polyvinyl chloride resin. Further, the impact resistance improving rubber used in the present invention includes A mottled, M mottled, NBR, chlorinated polyethylene, and EV, which are generally used as impact modifiers for pinyl chloride resin.
A (ethylene-acetic acid pi copolymer), acrylic modifier, etc., and is not particularly limited. There are no particular restrictions on the molding method; the gypsum needle crystal fibers, impact-improving rubber, polyvinyl chloride resin, and compounding agents such as stabilizers, lubricants, and processability improvers are mixed, and the mixture is extruded using two rolls and a single screw. machine・
Either obtain the molding material directly using a twin-screw extruder or a special compound mixer, or manufacture pellets using a two-roll extruder, Banbury mixer, single-screw extruder, Nito extruder, or a special compound mixer, and then inject the material. The molding material may be obtained by molding, blow molding, extrusion molding, calendar molding, melt spinning processing, etc. In order to realize the effects of the present invention, it is necessary to take measures to improve the dispersibility of the reinforcing material and rubber, since kneading the fibrous reinforcing material and rubber at the same time tends to result in poor dispersibility of the reinforcing material and rubber.

For example, it is also possible to knead and mold a pellet made by pre-kneading impact-improving rubber and vinyl chloride resin with gypsum fiber and vinyl chloride resin, or to mix and mold impact-resistant improving rubber with gypsum fiber and vinyl chloride resin. It is also possible to use a method of mixing and dispersing latex, drying this, and then performing cross-wire molding. Regarding the dispersibility of gypsum fibers in more detail, it is desirable that no aggregates of 100 r or more are present in the molded article 1 willow 3 when measured with N25 using an optical microscope.
The dispersibility of the rubber for improving impact resistance may be the same as that normally used for vinyl chloride resins, such as MBS.
Then, it is sufficient to disperse the rubber particles to a diameter of about 1600A. This can be measured using an electron microscope. The dispersion method is not limited to the methods exemplified above. The most appropriate dispersion method should be used to ensure good dispersion of the fibrous reinforcement and rubber in the polyvinyl chloride to ensure the desired physical properties. The polyvinyl chloride resin in the present invention refers to polyvinyl chloride resin, polyvinylidene chloride resin, vinyl chloride/vinylidene chloride copolymer, vinyl chloride/vinyl acetate copolymer, vinyl chloride/maleic anhydride copolymer, It includes copolymers such as vinyl chloride/ethylene copolymer, vinyl chloride/propylene copolymer, and modified resins such as chlorinated polyvinyl chloride resin, and these may be used alone or in combination. It is also possible.

Further, there are no particular limitations on the stabilizer for the polyvinyl chloride resin. The method of the present invention will be described in more detail by way of examples. In addition, the tensile strength is determined by the ASTM method, and the half height at failure is determined by a DuPont impact strength test piece with a thickness of 2.5 to 2.7 ribs and a uniform load of 300. Next, examples will be shown.

Example 1 Calcined gypsum LK9 was added to 9K9 water at 25°C and stirred for about 30 minutes to create a fine dihydrate gypsum slurry. This slurry was put into a reaction tank and heated at 12 pm for 13 minutes.
After heating at 0 qo for 5 minutes, steam was released, the liquid temperature in the reaction tank was cooled to 150 o'clock, the slurry was discharged, immediately passed through a furnace, washed with methyl alcohol, and heated to 110 o
It was dried at a temperature of o.

The obtained Q1-hemihydrate gypsum needle-like crystal fibers have a diameter of 0.5~
It is 1.5 Buddhas long and 80 to 150 Buddhas long. When this Q-1 anhydrous gypsum needle-like crystal fiber is dried for 700 minutes CI hr, an O-type anhydrous needle-like crystal fiber having a diameter of 0.5 to 1.5 mm and a length of 80 to 1,50 mm is obtained. This gypsum needle-like crystal fiber, polyvinyl chloride resin (degree of polymerization, looo), and M spots (Kanesu B-22, manufactured by Kaneka Yobuchi Chemical ■) were mixed as shown in Table 1 (lead was added as a stabilizer), After the belt was extruded and press-molded, test pieces were cut out and their physical properties were determined. For comparison, glass fiber diameter 10 inch chopped strands are shown in Table 1.
Mix as follows, create a molded product using roll press,
We sought physical properties. Table 1 Glass fibers do not improve impact strength despite a decrease in tensile strength, but gypsum fibers show a dramatic improvement in impact strength with only a slight decrease in tensile strength.

Example 2 In Example 1, the M spots were blended and molded in the same manner as in Table 1 using double the amount of vinyl chloride resin that had been mixed with vinyl chloride resin, and the physical properties were determined.

Table 2 Compared to Example 1, the impact strength was further improved and the effect of improved dispersion was observed.

Example 3 O-type anhydrous gypsum fiber 2 t% vinyl chloride 71M% impact-improving rubber shelf t% (mixed in advance with 6 wt% PVC) was extrusion molded and its physical properties were measured.

It is clear that the present invention is effective regardless of the type of rubber used to improve impact resistance. Table 3 Concubine/Shoden Elasuren 351A *2 Sumika Evatate R5011 Concubine 3 Kane Ace/FM Example 4 As shown in Table 4, O-type anhydrous gypsum fiber, vinyl chloride resin (degree of polymerization 1000), and M porridge (Kane Ace B-22) were used. It was mixed and molded, and its physical properties were determined.

For M old S, a material that had been mixed in advance with double the amount of vinyl chloride resin was used. As a comparative example, the physical properties of a sample not containing MBS are also shown. Table 4 It can be seen that impact strength was improved for all gypsum fiber filling amounts, and there was little decrease in tensile strength.

Claims (1)

[Claims] 1. 5% or more by weight of at least one kind of acicular crystal fibers of α-hemihydrate gypsum, type III anhydrite, or type II anhydrite, and 1 to 10% of impact-improving rubber. A reinforced polyvinyl chloride resin molding material that contains 2. The reinforced polyvinyl chloride resin molding material according to claim 1, which contains 5 to 70% by weight of gypsum needle crystal fibers. 3. The reinforced polyvinyl chloride resin molding material according to claim 1, which contains 10 to 50% by weight of gypsum needle crystal fibers.