JP3778881B2 - Method for producing antibacterial wood composite molding - Google Patents

Description

【００４０】
この表から分るように、メカノケミカル反応を行わせることにより、引張強さは９９％、弾性率は２７％、破断伸びは１３％向上する。
【００４１】
実施例２，３、比較例２，３
実施例１と同様にして、１６０℃又は１９０℃でメカノケミカル反応させることにより、表２に示す組成の木質系複合成形体を調製し、これを用いて実施例１と同様にして、板状成形体を作製した。
この板状成形体の機械的性質を測定し、表２示す。
【００４２】
【表２】

１）酸変性低分子ポリプロピレン系樹脂（三洋化成工業社製、分子量４００００）
２）低密度ポリエチレン「Ｌ５０２」（三菱化学社製、メルトインデックス：１．０）
３）ポリプロピレン「ＭＧ０５ＢＳ」（日本ポリケム社製、メルトインデックス：４５）
４）ゼオライト（和光純薬工業社製）
【００４３】
この表から分るように、メカノケミカル反応生成物を用いることにより、機械的性質の良好な複合体が得られる。
【００４４】
参考例１
実施例１で作製した板状成形体を５０ｍｍ四方の正方形に裁断したのち、オートクレーブ処理により滅菌して試験片（以下Ａという）３枚を準備した。
また、比較のためにポリピロピレンのみで板状成形体を作製し、同じく５０ｍｍ四方の正方形に裁断したのち、オートクレーブ処理により滅菌して試験片（以下Ｂという）６枚を準備した。
【００４５】
次に、大腸菌（Ｅｓｃｈｅｒｉｃｈｉａ ｃｏｌｉ ＩＦＯ３９７２）と黄色ブドウ球菌（Ｓｔａｐｈｙｌｏｃｏｃｃｕｓ ａｕｒｅｕｓ ＩＦＯ １２７３２）をそれぞれ、普通寒天培地に接種し、３５℃で２４時間前々培養したのち、これを普通ブイヨン培地に移し、３５℃で２０時間前培養した。
【００４６】
このようにして培養した菌液０．５ｍｌを、前記３枚の試験片Ａ及び６枚の試験片Ｂにそれぞれ接種し、試験片Ｂの中の３枚については、直ちに接種菌液を洗い落として、この接種菌液中の菌数を測定した。
残りの試験片Ａの３枚と試験片Ｂの３枚については、菌液接種後、３５℃、相対湿度９０％で２４時間培養したのち、接種菌液を洗い落して、この中における菌数を測定した。
このようにして得た各試験片３枚についての平均菌数を求め、表３に示す。
【００４７】
【表３】

【００４８】
この表から分るように、本発明の木質系複合材料は、大腸菌、黄色ブドウ球菌のいずれに対しても抗菌効果を示す。
【００４９】
参考例２
実施例１におけるポリプロピレンの代りに、同量の低密度ポリエチレンを用いた場合について、参考例１と同様の試験を行った結果を表４に示す。
【００５０】
【表４】

【００５１】
この表から分るように、本発明の木質系複合材料は大腸菌、黄色ブドウ球菌のいずれに対しても抗菌効果を示す。
【図面の簡単な説明】
【図１】 本発明の製造方法の１例の工程図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a wood-based composite molded article having an antibacterial action.
[0002]
[Prior art]
Trees belonging to the cypress family, such as cypress and hiba, contain hinokitiol, and it is known that the essential oil component extracted therefrom has a fragrance and exhibits antibacterial, insecticidal and antifungal properties.
[0003]
Therefore, the lumber produced from these trees is used as high-grade materials such as building materials, furniture, bathtubs, etc., but most of the scraps and sawdust generated during the processing are not used at all. It was only incinerated as wood waste or used for reclamation at best. After that, it was tried to collect bioactive substances and aromatic essential oils from these wastes by steam distillation or solvent extraction, but the operation is complicated, so the collection and transportation are expensive and the cost is high. It was not escaped and was not put into practical use industrially.
[0004]
By the way, hinokitiol (4-isopropyl-2-hydroxy-2,4,6-cycloheptatrien-1-one) is made from Taiwan cypress oil, Aomori hiba oil and Western red ceder oil. Although it is a crystalline substance present in these products, it is currently available as a synthetic product and is used as an additive for cosmetics, hair nourishing agents, toothpastes and the like. In addition, hinokitiol has attracted attention as a fragrance because it has a woody scent unique to cypress, and has antibacterial activity against bacteria such as Salmonella typhi, Escherichia coli, Shigella, Staphylococcus, fungi and caries. It has also been reported to be effective for the treatment of cancer and leukemia (“Fragrance Journal”, Vol. 17, No. 2, pp. 74-79, “Biological and Pharmaceutical Tikal Bulletin (Biol. Pharm. Bull), 16 (5), 521-523).
[0005]
For this reason, hinokitiol may be mixed with plastic and processed into storage containers, packaging films, textile products, etc., but hinokitiol has a low melting point of 52-53 ° C. and has sublimation properties. Because of its lack of miscibility with various plastics, it is difficult to mix and heat-mold into thermoplastic resins, so the desired properties of hinokitiol can be used as molded products with desired shapes and synthetic fibers. There wasn't.
[0006]
On the other hand, the physiologically active substances generally present in natural animals and plants are usually a mixture of a large number of substances, and the natural harmony is maintained so as not to give a strong action to the environment and organisms. If a specific active ingredient is decomposed as a single compound, the bioactive action becomes too strong and the harmony in nature may be disturbed. Therefore, these bioactive substances are in the original mixture state. It is desirable to use it as it is.
[0007]
Therefore, waste materials such as cypress and hiba are also advantageous to utilize the activity inherent to the physiologically active substance in the state of wood without extracting and isolating the physiologically active substance from them. As such a method of use, there has been no known method that can be particularly noticed, except that the waste material is powdered and used as a bath agent.
[0008]
[Problems to be solved by the invention]
Under such circumstances, the present invention provides a technique for effectively using a physiologically active substance existing in wood waste such as cypress and hiba while keeping it in a natural state as much as possible. It was made for the purpose.
[0009]
[Means for Solving the Problems]
The present inventors have incorporated a woody powder derived from a tree belonging to the cypress family into a thermoplastic resin without deteriorating the useful physical properties of the active ingredients contained therein , and molding it into a molded product. As a result of intensive research to develop a wood powder, when the above wood powder is subjected to a mechanochemical reaction with a wood adhesive component in the presence of certain weakly basic substances, the organic acids contained in the wood powder are Partially neutralized, the hydrolysis and denaturation of the wood part caused by organic acids during heating is suppressed, and the cellulose crystal, which is the main ingredient of the wood, is destroyed and amorphized to become a part in the middle of the polymer chain In this case, the molecular arrangement is disturbed, and a physiologically active substance such as hinokitiol is included in the disturbed cellulose molecular chain, and is stabilized against heat and light. It came to an eggplant.
[0010]
That is, the present invention adds at least one stabilizer selected from weakly basic substances to a mixture of a hinokitiol-containing wood powder and a wood adhesive component, and the wood powder becomes the wood adhesive component. It provides a method for producing an antibacterial wood-based composite molded article characterized in that the reaction product is mixed with a thermoplastic resin and molded after the mechanochemical reaction until a uniform wet state is obtained. is there.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The molded product obtained according to the present invention comprises a composite of a mechanochemical reaction product of a hinokitiol-containing wood powder and a wood adhesive component and a thermoplastic resin. For example, hinoki or hiba powder is used. And as woody powder, it is preferable to use waste materials generated during processing such as mill ends, sawdust and sawdust, and pruning waste materials.
[0012]
Sawdust and sawdust obtained immediately after normal processing contains 10% by mass or more of moisture, and thus hydrolyzes and foams during the mechanochemical reaction. It is preferable to dry it. This drying is performed at a temperature of 60 to 120 ° C. in as short a time as possible by, for example, hot air drying, vacuum drying, or vacuum drying. When the particle size of the woody powder is large, it is preferable that the particle size is 1 mm or less, preferably 0.5 mm or less in order to facilitate the subsequent mechanochemical reaction and extrusion molding. For this chopping, for example, a wheelie mill or a cutter mill is used.
[0013]
As the wood adhesive component used in combination with the hinokitiol-containing wood flour, cellulose having a large number of hydroxyl groups is preferable, and those having functional groups having reactivity with respect to the hydroxyl groups are preferable. As such an adhesive component for wood, a thermoplastic resin such as maleic acid or maleic anhydride-modified polyolefin is preferable.
[0014]
Examples of the polyolefin include homopolymers such as polyethylene, polypropylene, polybutylene, and polyisoprene, copolymers of ethylene and propylene, copolymers of ethylene and butylene, and other α-carbons having 5 or more carbon atoms. Copolymers with olefins, that is, copolymers such as low density linear polyethylene are used. These may be used singly or as a mixture of two or more. Furthermore, olefin oligomers can be used in place of these polyolefins.
[0015]
In addition, as the maleic acid or maleic anhydride modified polyolefin, polyolefin obtained by graft copolymerization of maleic acid or maleic anhydride is used. Polyethylene and polypropylene are readily graft copolymerized with maleic acid or maleic anhydride to form modified polyethylene or modified polypropylene. Since this modified polyolefin has a carboxyl group and an acid anhydride group, these portions easily react with a component having a hydroxyl group in the wood flour and develop affinity.
[0016]
In addition, thermoplastic resins such as vinyl acetate resins and ethylene-vinyl acetate copolymer resins that are commonly used as adhesives for wood, urea resins, melamine resins, phenol resins, epoxy resins, urethane resins, aqueous polymers-isocyanates Thermosetting resins such as prepolymers can also be used.
[0017]
The hinokitiol-containing wood powder and wood adhesive component are used in a mass ratio of 100: 1 to 100: 40, preferably 100: 5 to 100: 20. If the amount of the adhesive component for wood is less than this, the strength of the molding material becomes insufficient, and if it is more than this, the temperature rises in the mechanochemical reaction process, and there is a risk of forming a lump when melted. .
[0018]
In the method of the present invention, a masterbatch is first prepared by mixing a hinokitiol-containing wood powder and a wood adhesive component in a predetermined ratio and causing a mechanochemical reaction in the presence of a stabilizer.
[0019]
At this time, when a woody adhesive component is used, it is preferably pulverized in advance to a particle size of 1 mm or less in order to quickly combine it. In particular, when the pressure and shearing force of the pulverizer used for carrying out the mechanochemical reaction are small, it is preferable to further pulverize.
[0020]
If the wood adhesive component is thermoplastic, it can be heated to near its melting point if necessary, and if thermosetting, it must be crushed while raising the temperature to the curing temperature. It is.
[0021]
Next, the mechanochemical reaction in the present invention needs to be performed in the presence of a weakly basic substance. This weakly basic substance is added to suppress and stabilize the action of acidic substances such as organic acids present in the wood. The weakly basic substance is preferably an alkali hydrogen salt of an inorganic acid such as sulfurous acid, carbonic acid or phosphoric acid, such as sodium hydrogensulfite, sodium hydrogencarbonate, sodium dihydrogenphosphate, ammonium dihydrogenphosphate, etc. Further, alkali salts of organic acids such as acetic acid and lactic acid can also be used.
[0022]
This weakly basic substance is used in a proportion of 1 to 7 parts by mass, preferably 2 to 5 parts by mass, per 100 parts by mass of hinokitiol-containing woody flour, although it varies slightly depending on the type. If this amount is less than this, neutralization of acidic substances in the wood will be insufficient, and denaturation cannot be completely suppressed, and if more than this, the physical properties of the formed material will be reduced. Bring.
[0023]
The mechanochemical reaction in the present invention is carried out by pulverizing hinokitiol-containing wood powder, wood-based adhesive component and stabilizer while applying mechanical energy under dry conditions, that is, in the absence of a solvent. This mechanical energy is usually applied using a ball mill, roll mill, jet mill, attrition mill or high speed mixer. At this time, the temperature rises to 150 to 200 ° C. along with the grinding treatment. The time required for this mechanochemical reaction depends on temperature conditions and the amount of mechanical energy applied, but is usually in the range of 40 to 100 minutes.
[0024]
This mechanochemical reaction is first performed between the hinokitiol-containing wood flour and the stabilizer, and after forming a composite of both, the wood adhesive component is added and the reaction is continued to make the composite. Alternatively, from the beginning, a hinokitiol-containing wood powder may be added with a stabilizer and an adhesive component for wood at the same time and reacted to form a composite.
In addition, this mechanochemical reaction is advantageously performed in a non-oxidizing atmosphere, for example, a nitrogen atmosphere in order to avoid alteration of the reaction product due to oxidation.
[0025]
In this reaction process, the wood adhesive component approaches the hinokitiol-containing wood powder, or a complex of this with a stabilizer, at the molecular level, and coats and surrounds the wood powder particles. As a result, the wood powder is trapped and stabilized in the wood adhesive component.
[0026]
In the mechanochemical reaction in the present invention, when the shape of the added wood powder is not recognized, the wood adhesive component is melted, and the finely divided wood powder is uniformly wetted by the wood adhesive component and becomes wet. finish. At this time, a lump may be formed in the melt. At this time, the shearing force is adjusted by cooling the pulverizer or decreasing the rotation speed or pressure of the cutting blade, thereby eliminating the lump.
[0027]
The molded body is produced by using the mechanochemical reaction product thus obtained as a master batch and mixing it with a thermoplastic resin.
The thermoplastic resin in this case is not particularly limited, and can be arbitrarily selected from conventionally used thermoplastic resins according to the purpose of use. Examples of such thermoplastic resins include polyolefin, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyester, ABS resin, AES resin, poly (meth) acrylate, polycarbonate, and the like, but also silicon resin, fluorine resin, etc. Can also be used as desired.
[0028]
The molded body is a mixture of the mechanochemical reaction product and the thermoplastic resin so that the content of the final mechanochemical reaction product is 1 to 90%, preferably 10 to 50%, based on the total mass, Each component is uniformly dispersed by kneading at a temperature of 100 to 250 ° C. At this time, due to the presence of the stabilizer, it is possible to prevent the decomposition of the wood component due to the organic acid and the carbonization of the wood component due to heating even when using the above high temperature.
The kneaded product thus obtained can then be pelletized using a kneading extruder as desired.
[0029]
Next, the manufacturing method of this invention is demonstrated according to an accompanying drawing.
FIG. 1 is a process chart of an example of the production method of the present invention, in which raw Hiba wood flour is pulverized to a particle size of 0.5 mm or less and dried to a moisture content of 1% by mass or less.
Next, after adding a stabilizer and causing a mechanochemical reaction, an adhesive component for wood is added, and a mechanochemical reaction is further performed to prepare a masterbatch.
[0030]
Next, a thermoplastic resin is blended with this master batch to produce an antibacterial wood-based composite molding material, and then kneaded, extruded, and pelletized as desired.
The above two mechanochemical reactions can be made into one mechanochemical reaction by optionally blending the stabilizer and the wood adhesive component simultaneously.
[0031]
In the wood-based composite molding material thus obtained, if desired, additives commonly used in ordinary thermoplastic resin molding materials, for example, plasticizers such as calcium stearate and zinc stearate, zeolites, etc. In addition to fillers, compatibilizers such as Umex (manufactured by Sanyo Chemical Industries), resin modifiers, filler dispersants, antioxidants, UV absorbers, flame retardants, antistatic agents, lubricants, colorants, etc. Can be blended.
[0032]
【The invention's effect】
The molding material of the present invention has a woody scent specific to hinokitiol, exhibits broad antibacterial and antifungal properties against gram-positive bacteria, gram-negative bacteria, yeasts and molds, and further against termites, ticks, cockroaches, etc. In addition to exhibiting insecticidal properties, it maintains its efficacy over a long period of time, and is therefore suitable as a material for producing antibacterial, antiseptic, insecticidal containers, and packaging materials.
[0033]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
[0034]
The mechanical properties in each example were measured by the following method.
(1) Tensile strength;
Dumbbell-shaped test pieces were prepared according to JIS R1606 and measured according to a method according to JIS K6200.
(2) Elastic modulus;
Using the same test piece as in (1), measurement was performed according to a method according to JIS K6900.
(3) Elongation at break;
Using the same test piece as in (1), the measurement was performed according to a method according to JIS G0202.
[0035]
Example 1
Sawdust generated during processing of hiba wood was pulverized to a particle size of 500 μm or less using a cutter mill, and then dried at 100 ° C. for 30 minutes with a hot air dryer. Thereby, the water content of the Hiba wood flour became 1 mass% or less.
To 100 parts by mass of the dried hiba wood powder thus obtained, 2.5 parts by mass of sodium hydrogen carbonate and 2.5 parts by mass of ammonium dihydrogen phosphate were added, and this mixture was used using a high-speed mixer (2000 rpm). The mechanochemical reaction was performed at room temperature for 30 minutes while passing nitrogen.
[0036]
Next, the periphery of the mixer vessel is heated to 150 ° C., and 5 parts by mass of powdered maleic anhydride grafted polyethylene oligomer (manufactured by Sanyo Kasei Kogyo Co., Ltd., trade name “Yumex CA60”) is further added under the same conditions for 60 minutes The mechanochemical reaction was continued at a rate corresponding to one fifth of the volume of the content of the high speed mixer per minute per minute.
[0037]
Polypropylene is added to the master batch thus obtained to prepare a mixture having a Hiba wood flour content of 50% by mass, and pellets are formed at 170 ° C. by a conventional method using a twin-screw kneading extruder and a water-cooled pelletizer. Turned into.
The pellets were dried with hot air at 150 ° C. for 60 minutes, filled into a square mold (150 × 150 × 1 mm), and press molded at 180 ° C. for 4 minutes using a hot press molding machine to produce a plate-shaped molded body. did. A test piece was produced by punching the plate-like molded body into a dumbbell shape, and its mechanical properties, ie, tensile strength, elastic modulus and elongation at break were measured. The results are shown in Table 1.
[0038]
Comparative Example 1
100 parts by weight of Hiba wood flour used in Example 1, 2.5 parts by weight of sodium bicarbonate, 2.5 parts by weight of ammonium dihydrogen phosphate and the same powdery anhydrous as used in Example 1 After adding 5 parts by mass of maleic acid grafted polyethylene oligomer and mixing, a masterbatch was prepared without performing mechanochemical reaction.
Next, polypropylene was added to this master batch to prepare a mixture having a Hiba wood flour content of 50% by mass. A plate-like molded body was produced in the same manner as in Example 1, and its mechanical properties were measured. The results are shown in Table 1.
[0039]
[Table 1]

[0040]
As can be seen from this table, by performing a mechanochemical reaction, the tensile strength is improved by 99%, the elastic modulus is improved by 27%, and the elongation at break is improved by 13%.
[0041]
Examples 2 and 3 and Comparative Examples 2 and 3
In the same manner as in Example 1, a woody composite molded body having the composition shown in Table 2 was prepared by a mechanochemical reaction at 160 ° C or 190 ° C. A molded body was produced.
Table 2 shows the measured mechanical properties of the plate-like molded body.
[0042]
[Table 2]

1) Acid-modified low-molecular-weight polypropylene resin (manufactured by Sanyo Chemical Industries, molecular weight 40000)
2 ) Low density polyethylene “L502” (Mitsubishi Chemical Corporation, melt index: 1.0)
3 ) Polypropylene “MG05BS” (manufactured by Nippon Polychem, melt index: 45)
4 ) Zeolite (Wako Pure Chemical Industries)
[0043]
As can be seen from this table, a composite having good mechanical properties can be obtained by using a mechanochemical reaction product.
[0044]
Reference example 1
The plate-shaped molded body produced in Example 1 was cut into a 50 mm square and then sterilized by autoclaving to prepare three test pieces (hereinafter referred to as A).
For comparison, a plate-like molded body was prepared only with polypyropylene, cut into a square of 50 mm square, and then sterilized by autoclaving to prepare six test pieces (hereinafter referred to as B).
[0045]
Next, E. coli (Escherichia coli IFO 3972) and Staphylococcus aureus IFO 12732 were each inoculated on a normal agar medium, cultured at 35 ° C. for 24 hours in advance, and then transferred to a normal bouillon medium. For 20 hours.
[0046]
Inoculate 0.5 ml of the thus cultured bacterial solution into each of the three test pieces A and six test pieces B, and immediately wash off the inoculated bacterial solution for three of the test pieces B. The number of bacteria in this inoculum was measured.
For the remaining three specimens A and B, after inoculating the bacterial solution and culturing for 24 hours at 35 ° C. and 90% relative humidity, the inoculated bacterial solution is washed off and the number of bacteria in this Was measured.
The average number of bacteria for each of the three test pieces thus obtained was determined and shown in Table 3.
[0047]
[Table 3]

[0048]
As can be seen from this table, the woody composite material of the present invention exhibits antibacterial effects against both Escherichia coli and Staphylococcus aureus.
[0049]
Reference example 2
Table 4 shows the results of the same test as in Reference Example 1 when the same amount of low density polyethylene was used instead of polypropylene in Example 1.
[0050]
[Table 4]

[0051]
As can be seen from this table, the wood-based composite material of the present invention exhibits antibacterial effects against both Escherichia coli and Staphylococcus aureus.
[Brief description of the drawings]
FIG. 1 is a process chart of an example of a production method of the present invention.

Claims (5)

A state in which at least one stabilizer selected from weakly basic substances is added to a mixture of hinokitiol-containing wood powder and wood adhesive component, and the wood powder is uniformly wetted by the wood adhesive component A method for producing an antibacterial wood-based composite molded article , which comprises subjecting a reaction product to a thermoplastic resin and molding after a mechanochemical reaction until it becomes . Method for producing antibacterial wood composite molding according to claim 1, wherein performing the mechanochemical reaction in a non-oxidizing atmosphere. The method for producing an antibacterial wood-based composite molded article according to claim 1 or 2 , wherein a use ratio of the hinokitiol-containing wood powder and the wood adhesive component is 100: 1 to 100: 40 by mass ratio. The ratio is hinokitiol-containing wood powder 100 parts by weight per stabilizer manufacturing method according to claim 1, 2 or 3 antibacterial wood-based composite molded article according from 1 to 7 mass parts. Stabilizer sulfite, at least one of the method for manufacturing the antimicrobial wood composite molded article according to any one of 4 to claims 1 to weakly alkaline salts selected from among carbonates and phosphates.

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