JPH10273538A - Production of polyolefin composition containing woody material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. which does not exhibit discoloration, is excellent in moldability, and gives a molded article excellent in mechanical strengths by kneading a woody material and a polyolefin in a molten state so that the resultant compsn. has a specified specific energy. SOLUTION: This compsn. is given a specific energy of 0.20-0.30 kW/g. A known olefin homo- or copolymer or a blend of at least two polyolefins can be used here; for instance, a blend comprising 80 wt.% polypropylene and 20 wt.% polyethylene is suitable. The woody material is a lignocellulosic substance such as a wood flour or a wood pulp. A pref. compounding ratio of the polyolefin to the woody material is (90/10)-(30/70). Various kneader can be used, a twin-screw extruder being pref. The specific energy is adjusted by changing a screw arrangement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyolefin composition containing a wood material by melt-kneading a wood material and a polyolefin.

[0002]

2. Description of the Related Art A composition comprising a woody material and a polyolefin is conventionally known and used for furniture, building materials and the like. Wood flour is often used as a wood material. This is because a large amount of waste material is generated when cutting and using wood, and wood powder obtained by crushing the waste material can be obtained at low cost. By the way, the technique of using a wood material as a filler of a thermosetting resin such as a melamine resin or a phenol resin to improve the appearance and elasticity of these thermosetting resins has already been industrially established. The technology of blending materials with thermoplastics such as polyolefins still has problems to be improved. That is, when the wood material is mixed with the thermoplastic resin, the fluidity of the thermoplastic resin at the time of melting is reduced, which causes a reduction in molding processability, and in some cases, a reduction in mechanical properties such as impact strength of the molded product. . Furthermore, when the woody material is sufficiently melt-kneaded with the thermoplastic resin, the resulting composition is discolored to dark brown, which has a fatal problem of impairing commercial value.

[0003]

As means for solving the above-mentioned problems, for example, it is conceivable to chemically treat a woody material to increase the affinity between the woody material and the thermoplastic resin. Japanese Patent Publication No. 59-30176 discloses a wood powder-containing composite resin composition using a polyolefin modified with maleic anhydride or the like as a part of the polyolefin. However, the compositions disclosed in these prior arts have improved affinity between wood flour and thermoplastic resin,
This is a very significant technique in that properties such as moldability and strength are improved, but has not yet solved the problem of discoloration.

Accordingly, an object of the present invention is to provide a method for producing a woody material-containing polyolefin composition having good hue, in which discoloration is effectively prevented. Another object of the present invention is to provide a method for producing a wood material-containing polyolefin composition in which the problem of discoloration is solved and mechanical properties such as impact strength are improved.

[0005]

According to the present invention, there is provided a method for producing a polyolefin composition containing a woody material by kneading the woody material and a polyolefin using a kneader under conditions in which the polyolefin is melted. Is 0.2
A manufacturing method is provided, wherein the kneading is performed so as to be in a range of 0 to 0.30 KW / kg.

In the present invention, the specific energy of kneading indicates the kneading energy required per unit weight of the kneaded material, and can be calculated from the power consumption of the kneading machine. For example, taking a case where a continuous kneader such as an extruder is used as an example, the kneading composition is put into an extruder hopper, and the extruder is operated in a steady state, and the power consumption per hour A (KW / hr)
And the extrusion rate B (kg / hr) per unit time are measured.
The power consumption can be read from an integrating wattmeter provided in the extruder. Next, the extruder is operated idle, and the power consumption A ₀ (KW / hr) per hour at this time is measured. From these values, the specific energy of kneading S (KW / kg) is determined by the following equation. S = (A−A ₀ ) / B When kneading is performed in a batch manner using a kneader or the like, the power consumption A of the kneading machine when one batch is kneaded.
(KW) Power consumption of the kneader when one batch is run idle A
₀ (KW), and from the kneaded composition amount B (kg) of one batch,
By the same equation as above, the specific energy of kneading S (KW / k
g) can be obtained.

That is, in the present invention, when kneading a woody material such as wood flour and a polyolefin, by controlling the specific energy of kneading, not only the kneaded material but also the heat of the ordinary thermoforming degree is kneaded. Even when a history is given, the discoloration of the kneaded composition or the molded product has been effectively prevented. If the specific energy exceeds 0.30 KW / kg, discoloration of the kneaded composition will occur during kneading, and discoloration will occur due to subsequent thermoforming, even if discoloration does not occur during kneading. The specific energy is 0.20
If it is less than KW / kg, the wood material and the polyolefin are not kneaded sufficiently, and the wood material is not uniformly dispersed.
Mechanical properties such as impact strength of the finally obtained molded body are impaired.

The above specific energy is affected by the melt viscosity of the kneading composition and the like. For example, at the time of melt kneading, the specific energy required for kneading increases when the melt viscosity is high, and the specific energy required for kneading when the melt viscosity is low. Energy is reduced. Therefore, it is theoretically possible to set the specific energy within the above range by adjusting the physical properties and the kneading temperature of the kneading composition. However, the woody material is a natural product and contains various components other than the cellulose component, from those having a high volatility to those having a low volatility. In order to avoid the decomposition and generation of gas, the kneading temperature is set at 200 ° C.
C. or lower, and needless to say, melt-kneading must be performed at a temperature higher than the melting point of the olefin resin. For this reason, the range of the adjustment of the specific energy by adjusting the kneading temperature or the like is scarce. Therefore, in the present invention, the specific energy is set in the above-described range by changing the physical conditions of the kneading in the kneading machine, for example, changing the screw shape or the like. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

Polyolefins: Polyolefins used in the present invention include olefins known per se, such as homopolymers or copolymers of ethylene, propylene, butene, pentene, hexene, methylpentene, heptene, octene, nonene, decene and the like, Typical examples include polyethylene, polypropylene, and ethylene-propylene copolymer. The above homopolymer or copolymer may be used alone or as a blend of two or more. Can be. For example, a blend of polypropylene and polyethylene, in particular, a polyolefin blend containing 20% by weight or more of polypropylene and 80% by weight or less of polyethylene can be suitably used.

In the present invention, it is preferable that at least a part of the polyolefin is graft-modified with an unsaturated carboxylic acid or a derivative thereof in order to enhance the affinity between the wood material and the polyolefin. That is,
In the case where a material having at least a portion of which is graft-modified is used, the interfacial adhesion between the woody material and the polyolefin is good by kneading, and the moldability is particularly good, and the molding is excellent in mechanical strength. Goods can be obtained. Examples of unsaturated carboxylic acids and derivatives thereof used for graft modification include acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid (endosis-bicyclo [2, 2,1] Hept-5-ene-2,3
-Unsaturated carboxylic acids such as dicarboxylic acids, and anhydrides, halides, amides, imides of these unsaturated carboxylic acids,
Esters and the like can be exemplified, and maleic anhydride is particularly preferred. Further, the most preferred as such a graft-modified polyolefin is a graft-modified polypropylene, particularly an unsaturated carboxylic acid or a derivative thereof,
For example, the amount of modification with maleic anhydride is 0.1 to 20% by weight, preferably 0.1 to 10% by weight, more preferably 0.1 to 10% by weight.
5 to 10% by weight. These graft-modified polyolefins may be used in an amount of 0.1 to 10 based on the entire polyolefin.
% By weight, preferably 0.1 to 8% by weight, more preferably
It is preferred that the composition be blended at a ratio of 0.5 to 5% by weight.

The polyolefin described above in the present invention has a melt flow rate (MFR; ASTM D 1238-65T) at 230 ° C. and a load of 2.16 kg of 0.1.
1 to 200 g / 10 min, preferably 0.5 to 100 g /
Those having a range of 10 minutes, most preferably 0.5 to 50 g / 10 minutes are good. If the MFR is lower than the above range,
It becomes difficult to perform melt-kneading at a temperature that does not involve the decomposition of the woody material, and if it is higher than the above range, it tends to be difficult to obtain a molded article having excellent mechanical properties such as impact resistance.

Wood material: In the present invention, the wood material is
It is a lignocellulosic substance, and wood flour, woody pulp and the like are used. The raw wood and tree species are not particularly limited, but wood flour is generally preferably used. It is of course possible to use a material obtained by neutralizing wood acid in woody material with urea or the like. The polyolefin and the wood material may be polyolefin / wood material = 90/10 to 30/70, particularly 80
It is preferable to use them in a ratio of / 20 to 40/60 (weight ratio). If the amount of the wood material used is smaller than the above range, advantages of using the wood material, for example, advantages such as economy, improvement of properties such as appearance and elasticity may be impaired.

Other Compounding Agents In the present invention, besides the above-mentioned polyolefin and wood material, various known compounding agents can be used depending on the use. For example, inorganic fillers such as talc and calcium carbonate; organic fillers such as polyester and polyamide fibers; fluororesin oligomers, metal montanates,
Stearic acid, its metal salts, polyolefin wax,
A lubricant such as an acid-modified polyolefin wax; a flame retardant; a stabilizer; an ultraviolet absorber; an antioxidant; a plasticizer; a coloring agent such as a pigment or a dye;

Kneading method: In the present invention, as described above, the polyolefin, the woody material, and the various compounding agents used if necessary have a specific energy of 0.20 to 0.30.
Kneading is performed so as to be in the range of KW / kg. Examples of the kneading machine include a blender, a kneader, a mixing roll, a Banbury mixer, a single-screw or twin-screw extruder, and it is particularly preferable to use an extruder, especially a twin-screw extruder. The adjustment of the specific energy is performed by changing the screw arrangement in the case of a twin-screw extruder as an example. That is, the screw is configured by connecting fine blocks, and the specific energy can be adjusted by replacing the screw block and changing the screw shape. For example, in a forward pitch block, the specific energy is small, but in the case of a reverse screw shape, the specific energy increases. If the screw shape is tapered or a seal ring is provided, the specific energy increases. Therefore, since the length of the screw is constant, the specific energy can be adjusted to the above range by adjusting the length of the block where the specific energy is increased as described above. Also in the case of a single screw extruder, it is possible to adjust the specific energy by changing the screw shape and the like in the same manner as described above, but the degree of freedom in adjusting the specific energy is extremely small because there are few types of screw shapes. small. In this sense, it is advantageous in the present invention to use a twin-screw extruder having a large degree of freedom in adjustment. Furthermore, in the case of a batch-type kneader such as a kneader, the specific energy can be adjusted by changing the number of revolutions of the screw. In this case, the specific energy increases as the rotation speed of the screw increases.

[0015] In the present invention, the kneading temperature using the above kneader is 150 ° C to 200 ° C, preferably 160 ° C to 200 ° C.
The temperature is preferably set to 200 ° C, more preferably in the range of 160 ° C to 190 ° C. If the temperature becomes higher than this range,
Gas may be generated by decomposition of the woody material. Therefore, for example, when kneading using a twin screw extruder,
The temperature (barrel temperature) of the kneading zone is set in the above range, and the die exit temperature must be set to 200 ° C. or less. . Prior to kneading with an extruder, etc.,
If necessary, each kneading component is pre-mixed, and this pre-mixing is preferably performed at room temperature using a Henschel mixer or the like. This is because, if a large shearing force is applied or the film is exposed to a high temperature, discoloration may occur at this point.

Uses: The woody material-containing polyolefin composition thus obtained can be used as a molded article of various shapes by secondary molding such as press molding, or by extrusion molding using an extruder used for kneading. It is used in many fields such as industrial parts and building materials.
Typical applications are as follows. Baseboards, decorative veneers, door materials, exterior wall materials, vanities, countertop materials, foundation backing plates, window frames, wall materials, surrounding margins, handrails, handles, structural materials, civil engineering timber, pillars, floor pillars, decorative pillars , Seismic materials, wallpaper, joinery ceiling materials, base materials, tatami mats, floors, concrete panels, scaffolding materials, shielding boards, sound insulation boards, furniture box ceilings, doors, front board back boards, shelves, sleeve boards, curtain boards, Deck, backboard, seat plate, heating member, waterproofing material, antifungal material, antiseptic material, shutter plate, sleeve plate, waistboard, side plate, bath unit floor pan, bus ceiling, bus wall, bus, tub, sanitary ware, Housing materials and building materials such as toilet seats and toilet lids. Home appliances, radio TV receivers, cabinets, stereo cabinets, amplifier cabs, speakers, piano organ master boards, large roofs, rolled roofs, upper and lower scroll boards, etc.

[0017]

【Example】

(Example 1) As a polyolefin, 4 kg of polypropylene (B101W manufactured by Grand Polymer Co., Ltd.) having an MFR of 0.5 g / 10 min at 230 ° C. and M at 190 ° C.
A blend (230) of 3 kg of polyethylene having a FR of 0.03 g / 10 min (8200B manufactured by Mitsui Petrochemical Industries) and 100 g of modified polypropylene (3% by weight of maleic acid added)
(MFR at 10 ° C .: 10 g / 10 min) was used. This blend, 3 kg of wood flour and 50 g of lubricant were uniformly mixed by stirring at room temperature for 3 minutes with a Henschel mixer, and then a twin screw extruder BT40 (barrel setting temperature 180 ° C.) manufactured by Plastics Industrial Research Institute was used. The wood powder-containing polyolefin composition was obtained at an extrusion rate of 20 kg / 1 hour by changing the arrangement and adjusting the specific energy. At this time, the composition temperature at the die outlet was 195 ° C. The specific energy of the kneading was 0.200. The composition was molded by a press sheet molding method, and the obtained molded product was evaluated for hue and other physical properties. The profile extrusion moldability was also evaluated. Table 1 shows the results.

The method for evaluating the molding conditions and physical properties of the press sheet is as follows. [Press sheet molding conditions] 7 manufactured by Shindo Metal Industry Co., Ltd.
Use a 0 ton press molding machine. Heating temperature 180 ° C Preheating time 5 minutes Press pressure 50 kgf / cm ² Heating and compressing time 5 minutes Cooling time 5 minutes 50 kgf / cm ² Temperature 23 ° C Molded product sheet thickness 2 mm [Measurement method for evaluating physical properties] Tensile strength ASTM D 638 Bending Strength ASTM D 638 Flexural Modulus ASTM D 638 Izod Impact Strength ASTM D 256 Color The kneaded product after extrusion was visually observed. [Deformable extrusion property] Extrusion molding conditions: Molding machine: Single screw 50 mmφ extruder VFC-50 (manufactured by Tanabe Plastics Industry) full flight screw, L / D = 2
8, compression ratio = 4 Die die: L type, with sizing Molding conditions: Set temperature: C1 (under hopper) 160 ° C C2 170 ° C C3 180 ° C C4 180 ° C5 180 ° C H (cylinder head) 180 ° C D (die) 185 ° C. Screw rotation speed 22 min ⁻¹ Extruded amount 12 kg / h Take-off speed 1.6 m / min Extrusion molded strip The deformed extrudate was visually inspected for the presence of cracks. ：: No cracks were observed. Δ: Slight blemishes were partially observed. ×: Large creaking is observed. Extruded surface The surface state of the extruded molded product was visually observed. ：: The surface is smooth. ×: The surface is rough.

(Examples 2 and 3, Comparative Examples 1 to 3) Using a twin screw extruder BT40 manufactured by Plastics Industrial Research Institute or a twin screw extruder PCM65 manufactured by Ikegai Co., Ltd., the screw arrangement was changed and kneading was performed. Except for changing the specific energy,
A wood flour-containing polyolefin composition was prepared in exactly the same manner as in Example 1, and the molded product was evaluated in exactly the same manner. Tables 1 and 2 show the results together with the specific energy of kneading.
It was shown to.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

According to the present invention, when kneading a polyolefin and a woody material such as wood flour, by controlling the specific energy of the kneading, there is no change in hue, excellent moldability and excellent moldability. A wood material-containing polyolefin composition having excellent mechanical strength can be obtained.

Claims (8)

[Claims] 1. A method of producing a polyolefin composition containing a wood material by kneading a wood material and a polyolefin using a kneader under conditions in which the polyolefin is melted, wherein the specific energy is 0.20 to 0.30 KW / kg. Wherein the kneading is carried out so as to fall within the range of. 2. The method according to claim 1, wherein the polyolefin is polypropylene. 3. The method according to claim 1, wherein the polyolefin comprises at least 80% by weight of polypropylene and at most 20% by weight of polyethylene. 4. The production method according to claim 1, wherein at least a part of the polyolefin is graft-modified with an unsaturated carboxylic acid or a derivative thereof. 5. The polyolefin and wood material, wherein polyolefin / wood material = 90/10 to 30/70
The method according to claim 1, wherein the kneading is performed at a ratio of (weight ratio). 6. The method according to claim 1, wherein an extruder is used as the kneader. 7. The method according to claim 6, wherein the extruder is a twin screw extruder. 8. The production method according to claim 7, wherein the specific energy is adjusted to the range by changing the screw arrangement of the twin-screw extruder.