JPH08131045A - Liquid absorbing core and its production - Google Patents

Abstract

PURPOSE: To obtain a liquid absorbing core for a suction type heating transpiration device, applicable to an aqueous chemical solution, causing neither deterioration nor clogging of a core material by heating, having high traverse strength, by blending rayon and/or flax with a phenol resin and thermally curing the resin by heating under pressure. CONSTITUTION: A mixture of 5-500 pts.wt. of rayon and/or flax having 1-50mm, preferably 3-25mm average fiber length as reinforcing fibers and 100 pts.wt. of a phenol resin is heated under pressure, the phenol resin is thermally cured to give a porous sheet having open cells. The sheet is readily subjected to cutting processing, is applicable to an aqueous chemical solution due to no use of a binder and has excellent liquid absorbing properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid absorbent core used in a wicking type heating and vaporization device, and more specifically, one end of the liquid absorbent core is immersed in a liquid chemical to absorb the liquid, and the other end is heated to form the liquid chemical. The present invention relates to a liquid-wicking core used in a wicking type heating-transpiration device that evaporates to kill insects, aroma and the like.

[0002]

2. Description of the Related Art A wicking type heating evaporation device represented by an electric mosquito catcher is a device which sucks up a chemical solution by a liquid absorption core and heats it to evaporate it. Things have been devised. As the liquid absorbent core, felt, non-woven fabric, asbestos, etc. were used in the past, but when these were used, only the solvent in the chemical solution was volatilized first, or the liquid core was burnt. Therefore, it has been difficult to stably evaporate the drug over a relatively long period of time.

In order to solve this problem, in recent years, it is assumed that the absorbent core does not smolder even when heated for a long time, clogging due to thermal decomposition of the drug is prevented, and stable evaporation of the drug is performed. Inorganic powders such as silica, talc, and clay, and wood powders, charcoal powders, and the like, to which a sizing agent is added, and the mixture is molded by extrusion molding and then dried to have a specific oil absorption rate (for example, Japanese Patent Publication No. -40409 and JP-A-63-63330) have been devised and used. Further, in Japanese Patent Laid-Open No. 4-117303, an inorganic powder, which is applicable to an aqueous chemical solution,
Mix a mixture of organic substances and inorganic binder at 600 ° C
Liquid absorbent cores obtained by firing at 2000 to 2000 ° C. are shown.

[0004]

However, after adding a sizing agent to inorganic powders such as silica, talc, and clay and wood powder, carbon powder, etc., and molding the mixture by extrusion molding, etc., it is dried to obtain a specific oil absorption rate. The liquid-wicking core that has the complicated mixing ratio of various materials to achieve a constant oil absorption speed,
In addition, there is a problem in that it is difficult to set manufacturing conditions for manufacturing a product of stable quality because it is likely to be deformed during drying, and an inexpensive liquid absorbent core cannot be easily provided. Further, the bending strength of the liquid absorbent core is not always sufficient, and there is a problem that attention must be paid during handling. Further, as a sizing agent for solidifying the absorbent core, a water-soluble one such as starch or CMC is often used, and when the liquid to be absorbed is an aqueous liquid, the sizing agent by elution of the sizing agent is used. Deterioration of the core was unavoidable.

Further, a liquid absorbent core obtained by firing a mixture of an inorganic powder, an organic substance and an inorganic binder at 600 ° C. to 2000 ° C. can be applied to an aqueous chemical solution, but the cost and labor are further increased. There is a problem in that it is necessary to perform such a firing process, and dimensional changes due to firing must be controlled, and high quality control is required in order to obtain one having a certain performance and shape.

The present invention is intended to solve such a problem and does not cause deterioration or clogging of the core material due to heating.
It has a high bending strength, and since it does not use a sizing agent, it can be applied to aqueous chemical solutions, and its purpose is to provide an absorbent core of stable quality in a simple process. is there.

[0007]

The present invention achieves the above objects. First, the first invention is to use one or more reinforcing fibers 5 of rayon and hemp having an average fiber length of 1 to 50 mm. ~ 500 parts by weight is bonded to 100 parts by weight of the phenol resin in a uniform dispersed state, and has an open pore, the following invention, the following invention is based on 100 parts by weight of the phenol resin powder. Average fiber length 1 to 50
mm rayon and hemp one or more reinforcing fibers 5-5
A first step of dispersing and mixing 00 parts by weight in water to form a sheet, a second step of heating one sheet or a laminate of the above sheets under pressure to heat-set it to form a porous sheet, the above-mentioned porous And a third step of forming a liquid absorbent core by cutting the flexible sheet to form a liquid absorbent core.

The present invention will be described in detail below. The absorbent core of the present invention is a porous one having continuous pores composed of a phenol resin and rayon and / or hemp reinforcing fibers. In the liquid absorbent core of the present invention, the reinforcing fiber is bonded to the phenol resin in a uniformly dispersed state, and has a large number of small holes at the interface between the reinforcing fiber and the phenol resin. As the phenol resin used here, various phenol resins can be used. As the reinforcing fiber, one or more of rayon and hemp, which have a relatively low elastic modulus and absorb water, are used. The average fiber length of the reinforcing fibers must be 1 to 50 mm,
It is particularly preferably 3 to 25 mm. When the average fiber length is shorter than 1 mm, it is difficult to obtain a porous body and sufficient strength cannot be obtained. Even when the average fiber length exceeds 50 mm, it is difficult to obtain a porous body and it is difficult to obtain sufficient homogeneity of the fiber and the resin. The average fiber diameter of the reinforcing fibers is 2
˜100 μm, especially 5˜50 μm
It is preferred that

The mixing ratio of the phenol resin and the reinforcing fiber in the present invention must be 5 to 500 parts by weight, preferably 10 to 300 parts by weight, with respect to 100 parts by weight of the phenol resin. Particularly preferably 2
It is 0 to 200 parts by weight. If the mixing ratio of the reinforcing fibers is less than 5 parts by weight with respect to 100 parts by weight of the phenol resin, it is difficult to secure continuous pores. If it exceeds 500 parts by weight, it is difficult to mold or process it into a shape suitable for the liquid absorbent core.

The absorbent core of the present invention can also contain various other components. For example, in order to adjust strength and water absorption, inorganic fibers such as glass fibers and carbon fibers, and synthetic fibers such as polyester fibers may be added to a part of the reinforcing fibers. Further, in order to give coloring, carbon powder, pigment or the like may be added. In addition, antioxidants,
Various chemical additives such as fungicides can also be added. Since the absorbent core of the present invention uses rayon and / or hemp having a relatively low elastic modulus as a reinforcing fiber, it can be easily cut after molding, and is similar to the case of cutting wood normally. The method can be applied. Moreover, since the fibers of rayon and hemp have water absorbency, the liquid absorbent core of the present invention has a property of absorbing water and therefore can be applied to an aqueous drug solution.

The liquid absorbent core of the present invention can be manufactured, for example, by the following method. First, phenol resin powder 1
5 to 500 parts by weight of rayon and / or hemp reinforcing fibers are dispersed and mixed in water with respect to 00 parts by weight to form a sheet. As a result, the phenol resin and the reinforcing fiber are sufficiently dispersed and mixed, and a composite state is obtained in which the reinforcing fiber is uniformly dispersed in the phenol resin. The phenol resin is preferably used in the form of powder, and the particle size of the powder is preferably 48 mesh or less according to JIS standard. When dispersing and mixing the reinforcing fiber and the phenol resin powder in water, for example, it is preferable to use a binder, and the binder is a solid component of 1 to 1.
It is preferable to add 10% by weight, especially 3 to 5% by weight
It is preferable to add. Such binders include:
Bound anionic or cationic charges such as acrylic polymers or styrene / butadiene polymers containing, for example, bound sulfonium groups, isothiouronium groups, pyridinium groups, quaternary ammonium groups, sulfate groups, sulfonate groups or carboxylate groups. A polymer latex composed of a substantially water-insoluble organic polymer having

Further, when the reinforcing fiber and the resin powder are compounded in water, it is also preferable to use an organic coagulant. Examples of such an organic coagulant include aluminum polychloride (aluminum hydroxy chloride), Various organic flocculants such as partially hydrolyzed polyacrylamide, modified cationic polyacrylamide, diallyldiethyl ammonium chloride and the like can be mentioned. The amount of the aggregating agent added is preferably less than about 3% by weight,
It is particularly preferable to contain less than about 1% by weight. In addition, a viscosity modifier such as xanthan gum may be used for the purpose of adjusting the viscosity of the slurry in which the reinforcing fiber and the resin powder are dispersed in water.

A sheet is formed after forming a composite slurry of reinforcing fiber and phenol resin in water. To form a sheet, it is desirable to perform solid-liquid separation using a paper machine or the like in the same manner as in papermaking, so that the solid content in water becomes a sheet. The resulting moist sheet is dried in a dryer. By adjusting the amount per unit area of the sheet, it is possible to easily obtain a sheet having a desired weight within a range of 100 to 1000 g / m ² after drying.

Next, the dried one sheet or a laminate of two or more sheets is heated under pressure to cure the resin and then opened to obtain a porous composite sheet. At this time, pressurization brings the degree of thermal expansion to a desired range,
Although it is performed to suppress excessive thermal expansion, the condition at this time is that the sheet has a predetermined thickness set in advance, that is, pressure is applied so that pressure is not applied to the sheet beyond the predetermined thickness. desirable. Thus, in order to press the thickness of the sheet to a predetermined thickness, for example, between the two pressing flat plates made of metal such as a press machine, the sheet and the pressing flat plates around the sheet are provided. Place a spacer to prevent the gap from becoming narrower than the specified thickness and pressurize it, or put a sheet between the upper mold and the lower mold with a predetermined interval and pressurize. You can

Regarding the temperature and the holding time when heating under pressure, when the resin is cured and when two or more sheets are laminated, the adhesion between the sheets is quickly achieved, and the resin is not deteriorated. It is set within a range. When obtaining the porous composite sheet as described above,
It is not limited to the method of performing directly from the dried sheet,
A method in which one sheet or a laminate of two or more sheets is heated and pressed in advance and densified is used, and the sheet is thermally expanded to a predetermined thickness between press flat plates or dies as described above and then cured. It can be taken. This thermal expansion is caused by the fact that the reinforcing short fibers bent in the dense sheet return to their original state by the elastic recovery force when the resin is softened. Therefore, as a heating condition for forming a dense sheet in advance, it is necessary to perform the heating in a range of temperature and time such that the resin is made to flow while curing does not proceed.

Since the porous composite material comprising the thus obtained phenol resin and rayon and / or hemp reinforcing fibers is excellent in processability, it is usually processed in the same manner as wood or the like. The liquid absorbent core of the present invention is obtained by cutting into a shape suitable for a liquid absorbent core such as a round bar.

In the manufacturing method of the present invention, the bulk density of the porous composite material after hot pressing can be freely controlled by adjusting one or more of the weight of the sheets, the number of laminated sheets, the thickness at the time of molding, and the like. It is possible, and the continuous porosity of the liquid absorbent core obtained thereby can easily obtain a desired one in the range of 20 to 90%.

[0018]

In the liquid absorbent core of the present invention, when the phenol resin and the reinforcing fiber are heated under pressure to be thermoset, a porous sheet having continuous pores can be obtained by the function of the reinforcing fiber. Since the liquid-absorbent core has continuous pores, the liquid-absorbent core has a very good liquid-absorbing property, so that deterioration or clogging of the core material due to heating does not occur. Further, since it is heat-cured under pressure, it has appropriate porosity and high bending strength. Since the liquid absorbent core of the present invention uses rayon or hemp having a relatively low elastic modulus as the reinforcing fiber, cutting processing etc. can be easily performed after molding,
Further, since rayon and hemp have water absorbency, they are excellent in water absorbency and can be applied to aqueous chemical solutions.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 0.25 g of xanthan rubber as a viscosity modifier was added to 17.5 liters of water with stirring, and then rayon fibers having an average fiber length of 3 mm and a fiber diameter of 11 μm (Daiwabo) were used as reinforcing fibers. (Manufactured by [Co.]) (87.5 g) was added to this water and stirred for 5 minutes to disperse well. Then, 87.5 g of powder (manufactured by Unitika [Co.]] having a particle diameter of 30 to 50 μm as a phenol resin and 6 g of solid acrylic polymer latex as a binder were added to this dispersion, and then 0.5% by weight of cation aggregation was performed. 63 g of the agent (manufactured by Betz Laboratories, trade name: Betz 1260) was gradually added to cause coagulation to obtain a slurry. A sheet machine containing this slurry containing 17.5 liters of water [Kumagaya Riki Kogyo Co., Ltd.]
In addition to the above, a wet sheet was obtained by dehydration on a 0.18 mm screen, and then the obtained sheet was lightly compressed,
A rayon fiber reinforced phenolic resin sheet having a base weight of 325 g / m ² was obtained by drying at 110 ° C. At this time, the rayon fiber was 100 parts by weight with respect to 100 parts by weight of the phenol resin.

This sheet was made into 21 rectangular (185 × 7
0 mm), 21 sheets are laminated, and the periphery thereof is surrounded by a stainless steel spacer (length 200 mm, width 25 mm) having a thickness of 8 mm, and two stainless steel flat plates (250 mm × 250 mm × 5 mm) Sandwiched between
It was heated at 175 ° C. for 40 minutes under a pressure of 3 kgf / cm ² and then taken out to obtain a flat porous composite material having a thickness of 8 mm. The bulk density of this material was 0.85 g / cm ³ and the porosity was calculated to be 38%. This porosity can be calculated from the following formula, with the theoretical density being Ag / cm ³ and the bulk density being Bg / cm ³ . Porosity = [(A−B) / A] × 100 Next, this flat plate-shaped material was cut to obtain a cylindrical liquid-wicking core having a diameter of 7 mm and a length of 70 mm. The liquid absorption time of the liquid absorbent core was measured and found to be 3.5 hours. To measure the liquid absorption time, a commercially available oil-based insecticide (Earth Pharmaceutical Co., Ltd.)
15 mm from the lower end of the absorbent core was vertically soaked in the liquid, and the time required for the liquid to be sucked up and reach the upper end of the core was measured.

Example 2 0.25 g of xanthan rubber was added to 17.5 liters of water with stirring, and the fiber diameter of the reinforcing fiber was 1
0 to 14 μm hemp fiber (Brazil REMIE NOIL) 5 mm
87.5 g of the product cut to length was added to this water and stirred for 5 minutes to disperse well. Next, to this dispersion, 87.5 g of powder (manufactured by Unitika [Co.]] having a particle size of 30 to 50 μm as a phenol resin and 6 g of solid acrylic polymer latex were added, and then 0.5% by weight of a cationic flocculant (Betz). Laboratories, product name: Betz 1260) 63
The slurry was obtained by aggregating by gradually adding g. 0.18 m of this slurry was added to a sheet machine containing 17.5 liters of water [Kumagaya Riki Kogyo Co., Ltd.].
A hemp fiber reinforced phenolic resin sheet having a basis weight of 325 g / m ² was obtained by dewatering on a m screen to obtain a wet sheet, then lightly compressing the obtained sheet and drying at 110 ° C. . At this time, the hemp fiber was 100 parts by weight with respect to 100 parts by weight of the phenol resin.

This sheet is divided into 22 rectangular (185 × 7
It is cut into 0 mm) and 22 sheets are laminated, and the circumference is 8
mm stainless steel spacer (length 200 mm, width 2
5 mm) and surround it with a stainless steel flat plate (2
50mm x 250mm x 5mm) sandwiched between 2 sheets, 3k
It was heated at 175 ° C. for 40 minutes under a pressure of gf / cm ² and then taken out to obtain a flat porous composite material having a thickness of 8 mm. The bulk density of this material is 0.89 g / cm ³ ,
The porosity was calculated to be 35%. Next, this flat plate-shaped material was cut to obtain a cylindrical liquid absorbent core having a diameter of 7 mm and a length of 70 mm. When the liquid absorption time of this liquid absorbent core was measured,
It was 6 hours.

Example 3 A set of commercially available heat evaporation type insecticides (manufactured by Earth Pharmaceutical Co., Ltd.,
(Arsnow mat for 30 days) was prepared, the liquid absorbent core of the device was removed, and the liquid absorbent cores of Example 1 and Example 2 were attached instead. Each of these devices was installed in a room equivalent to 6 tatami mats, and it was heated for 12 hours a day, and stopped for 12 hours, and was used for 30 days. I was able to show the effect.

Example 4 Liquid absorbent wicks of Example 1 and Example 2 (diameter 7 mm, length 7)
The 3-point bending fracture load (0 mm) was measured. A universal testing machine (Shimadzu Autograph AG-5000) is used as the measuring device, and the distance between fulcrums is 40 mm and the crosshead speed is 3 mm.
The load immediately before the absorbent core was broken at / min was measured. Table 1 shows the results.

[0026]

[Table 1]

Comparative Example Five kinds of liquid absorbent cores (diameter 7 mm, length 70 mm) attached to a commercially available insecticidal liquid for a heat evaporation type insecticidal device were sufficiently dried,
The three-point bending fracture load was measured in the same manner as in Example 4. Table 1 shows the results. In addition, the commercial products A to D in the table are used for insecticidal liquids using a third petroleum as a solvent, and the commercial products E are liquid absorbent wicks used for aqueous insecticidal liquids. As is clear from Table 1, since the liquid absorbent core of the present invention has excellent breaking strength and has some flexibility, it is extremely unlikely to be broken during mounting.

Example 5 The same liquid absorbent core as in Examples 1 and 2 was immersed in water at room temperature for 1 hour and then taken out, and water drops were cut off to measure the weight. Further, the amount of water absorption was measured from the difference between the weight of the absorbent core and the weight of the absorbent core after it was sufficiently dried.
It absorbed 0.35 g and 0.32 g of water per m ^3, respectively.

Example 6 Liquid absorbent wicks similar to those in Examples 1 and 2 were immersed in water at room temperature for 30 days, then taken out and thoroughly dried. These absorbent wicks had no change in appearance and weight before immersion in water, and there was no difference in the three-point bending fracture load as compared with the case of Example 4. As the results of Example 5 and Example 6 show, the absorbent core of the present invention can sufficiently absorb water and does not deteriorate even in water for a long time, so that it can be applied to an aqueous chemical solution. It is a thing.

[0030]

As is apparent from the above description, the liquid absorbent core of the present invention is porous having continuous pores and has very excellent liquid absorbency, and deterioration or clogging of the core material due to heating. Does not occur, has a high transverse rupture strength, and can be applied to an aqueous drug solution.

Front page continuation (72) Inventor Yoshiaki Iwaya 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. Rayon having an average fiber length of 1 to 50 mm and 5 to 500 parts by weight of one or more reinforcing fibers of hemp are bonded to 100 parts by weight of a phenol resin in a uniformly dispersed state and have continuous pores. Liquid-wicking wick. 2. An average fiber length of 1 per 100 parts by weight of the phenol resin powder in the following three steps.
A first step of dispersing and mixing 5 to 500 parts by weight of one or more reinforcing fibers of rayon and hemp of -50 mm in water to form a sheet; heating one or more laminates of the sheets under pressure; A method for producing a liquid absorbent core, comprising: a step of thermosetting to form a porous sheet; and a third step of cutting the porous sheet to form a liquid absorbent core.