JP4155886B2 - Method for producing wax composition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a composition mainly composed of wax.
[0002]
[Prior art and problems to be solved by the invention]
As means for obtaining a composition mainly composed of wax such as a moisture-proof coating agent, conventionally, a method of mechanically mixing components of the composition mainly in a molten state (for example, see Patent Document 1 below), a wax emulsion is used. The method of using and mixing (for example, refer to the following Patent Document 2) has been used. However, the above method has the following problems.
[0003]
In the method of mechanically mixing in the molten state, since the viscosity of the wax in the molten state is low, when mixing with a solid or high-viscosity substance, sufficient shearing force is not applied to these materials to be mixed. It was difficult to obtain a uniform dispersion state of each component. In the method using a wax emulsion, since it is impossible to disperse the component below the particle size of the component constituting the emulsion, it is difficult to obtain a composition in a uniform dispersed state.
[0004]
[Patent Document 1]
JP-A-7-278510 [Patent Document 2]
JP 59-66598 A
Accordingly, an object of the present invention is to provide a continuous and efficient method for producing a wax composition, which can produce a composition mainly composed of a wax having a uniform dispersion of constituent components at a low cost.
[0006]
[Means for Solving the Problems]
The inventors have found that the above object can be achieved by mixing a composition mainly composed of wax at a temperature lower than the melting completion temperature of the wax.
[0007]
The present invention has been made on the basis of the above knowledge, and is a method for producing a composition mainly composed of wax, which is a mixture to be mixed with the wax and the wax at a temperature lower than the melting completion temperature of the wax. The present invention provides a method for producing a wax composition, characterized in that an external force is applied and mixed in a continuous kneader. Examples of the continuous kneader include a kneading extruder having a single axis or a plurality of axes, but a biaxial kneading extruder is preferable in consideration of kneading effects and equipment costs.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on preferred embodiments thereof.
[0009]
The wax composition of the present invention is mainly composed of wax, and polymer materials such as thermoplastic resins and elastomers, organic and inorganic powders, and the like can be selected as a mixture. Specifically, the production method of the present invention is particularly suitable when a viscous polymer substance having a viscosity higher than the melt viscosity of the wax is mixed or when a solid substance such as a powder is dispersed in the wax. Demonstrate the effect. This is because, by applying the production method of the present invention, a high shearing force can be applied to the mixture through the unmelted high-viscosity wax.
[0010]
The production method of the present invention can obtain a high effect when the composition ratio of the wax is 40 wt% or more, preferably 50 wt% or more, more preferably 60 wt% or more, and higher in a system in which the wax phase is a matrix. An effect can be obtained. Considering the case of inorganic powder having a high specific gravity of the mixture, a high effect can be obtained when the wax volume fraction is 40% or more, preferably 50% or more, more preferably 60 wt% or more. A higher effect can be obtained in a system in which the wax phase becomes a matrix.
[0011]
As the wax, vegetable wax, animal wax, mineral wax, petroleum wax, synthetic wax and the like can be used. (The wax described in Kenzo Fusegawa, “Characteristics and Applications of Wax”, Koshobo, 1993, 2nd revised edition, 1st page, 2nd page, Table 1.0.1 can be used.)
Examples of the plant wax include rice wax, carnauba wax, wood wax, and candelilla wax. Examples of the animal wax include beeswax, lanolin, and whale wax. Examples of the petroleum wax include microcrystalline wax and paraffin. Examples of the synthetic wax include polyethylene wax and Fischer-Tropsch wax, and examples of the mineral wax include montan wax, ozokerite, and ceresin. Any of these waxes can be preferably used. However, when a mixer having sufficient cooling capacity cannot be used, the low melting point component in the wax melts due to the temperature rise due to shear heat generation during mixing, and the wax It is preferable to use a wax having a low low-melting-point component because the viscosity decreases and sufficient shearing force may not be applied to the mixture. For the same reason, it is preferable to use a wax with less amorphous components. However, depending on the use of the wax composition, a certain amount of tackiness may be required in the living temperature range, so an appropriate amount of low melting point component or amorphous component is contained within a range that does not greatly affect the mixing. It may be preferable to do this. From this viewpoint, the melting point measured by the method described in JIS K2235-5.3.2 is preferably 40 ° C or higher, more preferably 60 ° C or higher.
[0012]
Further, when biodegradability is required for the wax composition, it is preferable to use a component having a biodegradability (as defined in JIS K6950) of 50% or more as a constituent component of the composition. It is more preferable to use the above.
[0013]
Prior to supplying the wax to a continuous kneader, the wax is appropriately sized pellets or powder (for example, having an average diameter of 2) by a pulverizer, an extruder, or a method of cooling droplets after melting. 10 mm pellets, powder having an average particle size of 1 mm or less). However, the wax is cooled after being supplied in a molten state at a temperature equal to or higher than the melting completion temperature without being formed into pellets or powder. You may mix at the temperature below melting completion temperature.
[0014]
The polymer substance can be used for the purpose of modifying physical properties or adding functions in a solid or molten state of wax. For example, solid state mechanical strength (breaking strength, impact strength, bending strength, flexibility, etc.), improvement of adhesion to other materials, improvement of melt viscosity in the molten state, and the like.
[0015]
Examples of the polymer substance include crystalline polymers such as polyolefin resins, polyester resins, and polyamide resins, uncrosslinked rubber, polyester, polyamide, polystyrene, and poly (meth) acrylic copolymers. Noncrystalline polymer or low crystalline polymer. However, in order to finely disperse the polymer material to be mixed, in the case of a crystalline polymer, it is preferable to melt at a desired mixing temperature that is not higher than the melting end temperature of the wax. In this case, those having a glass transition temperature not higher than the desired mixing temperature which is not higher than the melting end temperature of the wax are preferable.
[0016]
Specifically, the crystalline polymer includes ethylene-α olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, polycaprolactone, polybutylene terephthalate adipate, polybutylene succinate adipate. Examples of the polymer having a low melting point such as an amorphous polymer include isoprene rubber, natural rubber, poly d, l-lactic acid and the like, and these can be used alone or in combination.
[0017]
When biodegradability is required for the wax composition, natural rubber or synthetic isoprene rubber is particularly preferably used as the biodegradable polymer having a high effect on property modification. In the mixing of wax and natural rubber or synthetic isoprene rubber, the production method of the present invention exhibits a very high effect, and a composition having a physical property-modifying effect that has not been obtained conventionally can be used without using a solvent or the like. Obtainable. By mixing the wax and natural rubber or synthetic isoprene rubber by the method of the present invention, it becomes possible to mix the natural rubber or synthetic isoprene rubber very uniformly in the wax, and the melt viscosity of the wax is made very high, Effects such as greatly improving the brittleness of the wax below the wax melting point can be obtained.
The polymer substances can be used alone or in combination of two or more.
Prior to supplying the polymer substance to a continuous kneader, pellets or powders of an appropriate size (for example, pellets having an average diameter of 2 to 10 mm, average particle diameter of 1 mm or less) are obtained by a pulverizer or a crusher. (Powder).
[0018]
In addition, when the production method of the present invention is used, organic powders such as corn starch, starch, various polymer powders, and inorganic powders such as titanium oxide, talc, mica, smectite, and silica are also uniformly dispersed in the wax. be able to. In particular, when a relatively hydrophilic powder is dispersed in a highly hydrophobic wax, the powder agglomerates above the melting point of the wax and fine dispersion is impossible. It is possible to obtain high dispersibility by using.
[0019]
The wax composition of the present invention may contain an antioxidant, a colorant, a dispersion aid, and other additives as necessary as long as they do not affect the mixing.
[0020]
The continuous kneader used in the present invention is preferably a twin-screw kneading extruder having two screws that can rotate in the same direction or in different directions.
[0021]
Next, the manufacturing method of the wax composition of this invention is demonstrated.
[0022]
The method for producing the wax composition of the present invention is such that the wax and the mixture are continuously at a temperature lower than the melting completion temperature of the wax, preferably at a temperature equal to or lower than the melting peak temperature obtained from a melting curve obtained by DSC measurement. Mix continuously with a kneader to obtain a composition. When there are a plurality of melting peaks, it is preferable to mix them at a peak temperature or less at the peak with the largest heat of fusion. When the wax and the mixture are mixed at a temperature equal to or higher than the melting point of the wax, the viscosity of the wax rapidly decreases due to the melting of the wax, so that sufficient shearing force is not applied to the mixture, so that the mixing is insufficient. Thus, it becomes difficult to obtain a uniform composition. By mixing at a temperature lower than the melting completion temperature of the wax, unmelted wax crystals remain, so the wax can be treated as a fluid with high viscosity apparently, which is generally done The wax and the mixture can be mixed by the same method as the compound of the plastic material.
[0023]
As a method for selecting a preferable mixing temperature, there are the following methods. From the melting curve obtained by DSC measurement, the total endotherm of the molten wax component is ΔH and the temperature range where the ratio ΔH ′ / ΔH of the endotherm on the lower temperature side than the mixing temperature is preferably 0.7 or less, Good mixing is possible in a temperature range of more preferably 0.5 or less, and even more preferably in a temperature range of 0.3 or less. There is no problem in performing the mixing at a temperature lower than the melting start temperature of the wax, but in the case of a hard wax with high crystallinity, it may be preferable to have a viscosity at the mixing temperature in order to obtain a uniform mixture. In this case, the lower limit temperature of ΔH ′ / ΔH is preferably selected to be 0.03 or higher, more preferably 0.05 or higher. As a similar concept, when mixing at a temperature near or lower than the melting start temperature of the wax, an appropriate amount (preferably 20 wt% or less, more preferably 10 wt% or less) of an oil component having a plasticizing effect of the wax is used. It is also possible to add.
[0024]
The optimum mixing temperature can be appropriately selected from the above mixing temperatures in accordance with the physical properties of the mixture. For example, when the mixture is an amorphous polymer, it is preferable to mix at or above the glass transition temperature of the amorphous polymer. When the mixture is a crystalline polymer, the temperature is preferably equal to or higher than the melting point of the crystalline polymer. When the mixture is an inorganic or organic powder, mixing is performed at a temperature sufficiently lower than the melting completion temperature of the wax (for example, a temperature lower than the melting start temperature of the wax) to facilitate uniform dispersion of the powder. It is preferable to do. However, mixing at a temperature lower than the glass transition temperature of the wax may cause adverse effects such as deterioration of the dispersion state or excessive load on the mixing device because the wax is too hard. It is preferable to mix above the transition temperature. In addition, considering the temperature dependence of the wax and the mixture, it is preferable to adjust the mixing temperature so that the physical properties of the two are optimal for mixing.
[0025]
The melting completion temperature, melting peak temperature, and ratio ΔH ′ / ΔH of ΔH and ΔH ′ in the present invention can be determined by, for example, the following method.
Measuring machine: Model DSC220 of Seiko Electronics Industry Co., Ltd.
Sample container: product number PN / 50-020 (aluminum open sample container, capacity 15 μl) and product number PN / 50-021 (aluminum open sample container crimp cover)
Sample weight: about 10mg
Temperature increase rate, temperature decrease rate: 5 ° C / min
Measurement temperature range: The optimum range is selected according to the wax used. The melting completion temperature and melting peak temperature are determined using data obtained by once melting, crystallizing at a rate of 5 ° C./min, and then increasing the temperature again at a rate of 5 ° C./min.
Specific examples include: [First heating process] from 30 ° C. to 130 ° C., [Temperature cooling process] from 130 ° C. (held for 5 minutes) to 30 ° C., [Second heating process] from 30 ° C. to 130 ° C. The measurement is performed continuously and the data of the second heating process is used.
Melting completion temperature: As shown in FIG. 1, the temperature at the point where the tangent of the base line on the high temperature side of the melting peak intersects with the tangent of the point located at 1/5 peak height of the high temperature side inclined line of the peak. Let it be the melting completion temperature. When there are a plurality of peaks, the peak located on the highest temperature side is selected to determine the melting completion temperature.
Main peak temperature: The peak temperature of the melting curve is determined from the above data. In the case of having a plurality of peaks, the peak having the largest heat of fusion is selected and used as the melting peak temperature.
ΔH: Total value of endothermic amounts of all melting peaks ΔH ′: Endothermic amount below the mixing temperature
There is no particular limitation on the means for supplying the wax and the mixture to the continuous kneader, both can be supplied simultaneously from one hopper provided in the continuous kneader, and two or more hoppers are provided. It is also possible to supply the mixture from the upstream hopper in the extrusion direction and supply wax from the downstream hopper. The wax can be supplied with a pump in a molten state.
[0027]
The kneading conditions of the wax and the mixture are not particularly limited, but it is preferable that the wax is mixed in a state where wax crystals remain. In order to obtain a uniform mixed state, the temperature is preferably set to a temperature equal to or lower than the wax melting completion temperature. Therefore, it is preferable that the kneading part outer cylinder (barrel) of the kneader has a specification capable of arbitrarily controlling the temperature.
[0028]
Since the composition obtained by the above method may contain bubbles during the kneading process, defoaming may be performed to remove the bubbles. A general method can be used for defoaming. For example, a method of maintaining the temperature above the melting temperature of the wax in a thermostatic chamber under reduced pressure, a method of mixing at a temperature equal to or higher than the melting temperature of the wax under reduced pressure using a mixing device such as a kneader having a pressure reducing means, and the like are used.
[0029]
When kneading using a twin-screw kneader extruder as a continuous kneader, a depressurization zone heated above the melting temperature of the wax is provided behind the mixing zone controlled below the wax melting completion temperature for defoaming. You can also select this method. It is also possible to perform kneading and defoaming by combining a plurality of biaxial kneading extruders, or a combination of a biaxial kneading extruder and a single screw kneading extruder. Of course, defoaming may not be necessary depending on the purpose of use or processing after mixing.
[0030]
When natural rubber or isoprene rubber is used as the mixture, it is preferable to heat the composition obtained to make the dispersion state of the wax and the mixture more uniform above the melting temperature of the wax. .
[0031]
According to the production method of the present invention, the wax composition of the present invention can be produced in a high yield in a short time, and the mixture can be uniformly dispersed in the wax. In particular, when the wax is mixed with natural rubber or isoprene rubber, extremely uniform dispersion is possible even when the wax is in an unmelted state.
[0032]
The wax composition obtained by the production method of the present invention is particularly preferably used as a moisture-proof composition or adhesive composition mainly composed of wax. In addition, since a wax composition can be obtained without using any organic solvent in the production process, it is extremely safe in various fields including food packaging materials by using the wax composition obtained by the production method of the present invention. Products can be provided.
[0033]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not restrict | limited to a present Example at all.
[0034]
A wax composition was prepared as in Example 1 and Comparative Examples 1 and 2 below. And about this composition, the uniformity of dispersion | distribution was evaluated as follows. Evaluation of dispersibility is carried out by heating the composition above the melting point of the wax and defoaming it, then extending it to a thickness of about 5 mm in the molten state and visually checking for the presence of a granular mixture. It was. The granular material was judged to be in an undispersed state.
[0035]
[Example 1]
Microcrystalline wax (manufactured by Nippon Seiwa Co., Ltd., product number “Hi-Mic-1070”, melting completion temperature: 86 ° C., main peak temperature: 44 ° C.) was frozen and pulverized by a pulverizer, and pulverized microcrystalline wax was 2 mm to 10 mm. Sieving was performed.
Further, isoprene rubber (manufactured by Nippon Zeon Co., Ltd., product number Nipol-IR2200) was extruded into a strand shape from a Φ3 mm die by a single-screw kneading extruder and processed into a pellet shape. Note that calcium carbonate was used as an anti-blocking agent in order to prevent rubber from sticking to each other during cutting.
[0036]
As shown in FIG. 2, using a twin-screw kneading extruder extruder (“KEX-40S” manufactured by Kurimoto Seiko Co., Ltd.) 1, the microcrystalline wax after sieving pulverized into the first supply port 2 The fixed amount was supplied to the third supply port 5 at a rate of 35 g / min. Also, the pelletized isoprene rubber was charged into the second supply port 3 and quantitatively supplied to the third supply port 5 at a rate of 15 g / min by the quantitative supply machine 14. The microcrystalline wax and isoprene rubber supplied to the third supply port 5 are supplied to the kneading screw portion of the twin-screw kneading extruder extruder 1 and at a rotation speed of 20 rpm, each barrel temperature is a temperature below the completion of melting of the microcrystalline wax. The kneading was performed at a certain temperature of 35 ° C. ΔH ′ / ΔH was 0.09. The weight ratio of the supplied microcrystalline wax and isoprene rubber is 7: 3.
[0037]
The obtained composition was white including bubbles, and it was confirmed that the dispersion of each component was uniform. The obtained composition was defoamed in a dryer at 110 ° C., a nitrogen stream, −500 mmHg, and the dispersion state was confirmed again in the molten state. As a result, the composition was transparent and uniform, and the presence of undispersed natural rubber. Could not be confirmed.
[0038]
[Comparative Example 1]
Production was carried out in the same manner as in Example 1 except that kneading was carried out by controlling each barrel temperature of the twin-screw kneading extruder extruder in Example 1 to 100 ° C., which is around the melting completion temperature of the microcrystalline wax.
[0039]
The obtained composition was translucent and contained bubbles, and an unkneaded isoprene rubber could be confirmed. The obtained composition was defoamed in a dryer at 110 ° C., a nitrogen stream and −500 mmHg, and the dispersed state was confirmed again under a molten state. As a result, the presence of undispersed isoprene rubber was confirmed.
[0040]
[Comparative Example 2]
Using a pressure kneader (DS0.3-3 type) manufactured by Moriyama Seisakusho, 1800 g of microcrystalline wax (manufactured by Nippon Seiwa Co., Ltd., product number “Hi-Mic-1070”) in a kneading container of the pressure kneader And 600 g of isoprene rubber (manufactured by Nippon Zeon Co., Ltd., product number Nipol-IR2200) were added and kneaded for 5 minutes at a rotation speed of 20 rpm, and then 600 g of the same wax was added and kneaded for another 10 minutes. The kneading was performed by flowing cooling water at 10 ° C. through the mixing vessel and the rotor, and with all the heaters turned off. The maximum temperature of the mixture during kneading was 37 ° C. (indicated temperature of the thermometer in the mixing container), and the temperature of the composition after completion of kneading was measured directly with a contact thermometer and found to be 36 to 42 ° C.
[0041]
It was confirmed that the obtained composition was white including bubbles and was in a uniform dispersed state. The obtained composition was defoamed in the same manner as in Example 1, and the dispersed state was confirmed again in the molten state. As a result, it was a transparent and uniform composition, and the presence of undispersed isoprene rubber could not be confirmed.
[0042]
【The invention's effect】
According to the present invention, there is provided a method for producing a composition mainly composed of a wax having a uniform dispersion of each component in a short time and at a low cost with a high yield.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for obtaining a melting completion temperature and a melting peak temperature from a DSC measurement result.
FIG. 2 is a diagram schematically showing a continuous mixer used in the present invention.
[Explanation of symbols]
1 Twin-screw kneading extruder (continuous kneading machine)
2 1st supply port 3 2nd supply port 4 Fixed quantity feeder 5 3rd supply port

Claims (4)

A method of manufacturing a wax composition mainly of wax, which comprises a step of adding and mixing an external force in a continuous kneader object mixture is mixed with the wax and the wax,
The mixing temperature of the wax and the mixture to be mixed is lower than the melting completion temperature of the wax and the mixing temperature with respect to the total endothermic amount ΔH of the molten wax component obtained from the melting curve obtained by differential thermal analysis measurement. A method for producing a wax composition, characterized in that the temperature is 0.7 or less in terms of the ratio of endothermic amount ΔH ′ on the low temperature side (ΔH ′ / ΔH) . Method of manufacturing the mixture comprises an amorphous polymer as the temperature during mixing is not less than the glass transition temperature of the non-crystalline polymer according to claim 1 Symbol placement of wax composition. The method for producing a wax composition according to claim 2 , wherein the amorphous polymer is isoprene rubber or natural rubber. The method for producing a wax composition according to claim 3, wherein the composition obtained by the mixing is heated to a temperature equal to or higher than the melting temperature of the wax.

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