JPH0585591B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a road antifreeze point depressant for the purpose of preventing or delaying freezing of road surfaces, etc., and a road antifreeze agent and antifreezing road pavement using this freezing point depressant. Concerning materials and anti-icing paving methods for roads. [Prior art] As a method for preventing road icing using antifreeze agents,
There are two main types. One is the spraying of substances that lower the freezing point of water, such as agents such as sodium chloride (NaCl) and calcium chloride ( _CaCl2 ) (hereinafter collectively referred to as freezing point depressants), or mixtures containing them, on the road surface. The other method is to impregnate an antifreeze agent inside the road pavement layer (for example, an asphalt layer) (hereinafter referred to as a road-embedded type). The present invention relates to a road-embedded antifreeze agent comprising a novel freezing point depressant and a particulate mixture in which the same is added and impregnated, a road antifreezing paving material in which the antifreezing agent is added to a road paving material, and a road antifreezing agent using this paving material. This invention relates to a method for preventing paving. Spraying agents are in a completely different technical field from the present invention, but since they are somewhat related, a brief explanation will be provided. Sodium chloride (NaCl) and calcium chloride (CaCl ₂ ) are commonly used as spraying agents, but due to pollution problems such as metal corrosion and environmental pollution, chlorine ions (Cl ^- ) are often used. Various inorganic and organic substances are being researched as drugs that do not contain
Proposed. (Example: Japanese Patent Application Publication No. 58-11578,
58-19717) Many methods have also been proposed for mixing and adding metal anticorrosive agents and other substances. (Example: Japanese Patent Application Publication No. 1983
-195178, JP-A-61-28576) In addition, there are methods to fix the spray agent on the road surface and make it difficult to scatter (e.g., JP-A-56-59904), and additives to improve the sustainability of the antifreeze effect ( Example: Tokukai Akira
58-11577). On the other hand, regarding road-embedded antifreeze agents, Japanese Patent Publication No. 60-4220 is known in Japan. This involves covering an antifreeze component (freezing point depressant, etc.) with an outer coating and encapsulating it, and then mixing the particles into the pavement layer at a rate of several percent. As the pavement layer wears down, new capsules are gradually exposed and crushed on the surface.
Since the freezing point depressant inside is leached out, the effect lasts for the life of the pavement layer itself. West German Patent No. 2512691 relates to a similar road-embedded antifreeze agent. This is the above-mentioned special public service in 1986.
This is an attempt to solve the high cost and other problems of the encapsulating agent proposed in No. 4220, by filling the pores of a naturally occurring porous aggregate such as lava with a freezing point depressant, and applying the particles to the pavement layer. It is mixed in at a rate of several percent. The purpose and action are similar to those of an encapsulating agent, but it is inexpensive, and the porous aggregate itself has the advantage of being a substitute for aggregate used as an additive in ordinary paving. The invention of West German Patent No. 2512691 has been further improved in European Patent No. 0153269. i.e. West German Patent No. 2512691
The problem of stickiness due to the hygroscopicity of the antifreeze component of the invention of No. 1 is improved, which causes problems in storage, antifreeze production, and mixing during paving.
Improvements have also been made to prevent deterioration in the strength of the pavement layer due to contamination. That is, in order to improve hygroscopicity, the entire fine particle mixture as an antifreeze agent is made hydrophobic (hydrophilic), while the freezing point depressant (hydrophilic) filled in the pores of a porous component such as lava is made hydrophobic. The anti-freeze effect is still not fully satisfactory, especially at low temperatures. The reality is that the antifreeze effect does not meet the needs of users. [Problems to be Solved by the Invention] The present invention uses an antifreeze agent containing a novel freezing point depressant as an active ingredient to dramatically improve the antifreeze performance and solve all of the drawbacks of the prior art described above. Specifically, the antifreeze agent of the present invention exhibits an extremely excellent antifreeze effect even in extremely cold regions. In addition, the antifreeze agent of the present invention has a hydrophobic (water repelling) property as a whole of the fine particle mixture, but the freezing point depressant filled in the pores of the porous component gradually melts when it comes into contact with rain and snow. It is important that it maintains its ability to leach out and exhibit its antifreeze function. [Means and effects for solving the problems] The present invention provides: 1. A freezing point product for road anti-freezing which contains as an active ingredient a reaction product obtained by adding phosphoric acid and organic carboxylic acid to dolomite and reacting the mixture. Depressants. 2 The ratio of phosphoric acid and organic carboxylic acid used is 1:1 or more
10. The freezing point depressing agent for road anti-freezing according to claim 1. 3 a Hydrophilic particles; b one or two or more selected from the group consisting of calcined hydrophobic pearlite particles, expanded mica particles, shirasu balloon particles, and synthetic resin porous particles;
A road comprising a mixture of hydrophilic particles and hydrophobic particles consisting of hydrophobic porous particles and the freezing point depressant for road anti-freezing according to claim 1 or 2, which is incorporated into the pores of the hydrophobic porous particles. Antifreeze. 4. The road antifreeze agent according to claim 3, wherein the hydrophilic particles are quartz powder. 5 The hydrophilic particles are one or more selected from the group consisting of lava powder, pumice powder, and foamed glass powder.
The road antifreeze agent according to claim 3, which is a hydrophilic porous particle. 6. The road antifreeze agent according to any one of claims 3 to 5, wherein the particle size of the mixture is 0.2 mm or less, preferably 0.1 mm or less. 7. The compounding ratio of the hydrophobic particles is 5 to 75% by weight per 100% of the hydrophilic particles or quartz powder, according to any one of claims 3 to 6.
Road anti-icing agent. 8 1 or 2 selected from cement and carbon powder
The road antifreeze agent according to any one of claims 3 to 7, which contains the above. 9. A road paving material for preventing freezing, which is obtained by blending the freezing point depressant for road antifreezing according to claim 1 or 2 into the road paving material. 10 A road paving material containing the road antifreeze agent according to any one of claims 3 to 8,
Road paving material for freezing prevention. 11. A road anti-freezing paving method, which comprises coating a road with the anti-freezing road paving material according to claim 9 or 10. ” related. In order to achieve the above-mentioned objectives and tasks, the present inventors conducted research on the compositional components of the previous antifreeze agent from various angles, and as a result, among the compositional components, the present inventors found that among the compositional components, the present invention was mainly used as a freezing point depressant. We discovered that salt, etc., have limited effectiveness, and that using such freezing point depressants would not achieve our goals, so we conducted research and development to create a new freezing point depressant in order to use a higher performance freezing point depressant. invented. Furthermore, when a freezing point depressant is directly mixed into road paving materials, unnecessary moisture is brought into the road paving material due to the hygroscopicity of the freezing point depressant, which tends to reduce pavement strength. The present invention was completed based on the discovery that the function as an antifreeze agent can be dramatically improved by incorporating the agent into the pores of special porous particles. According to the research conducted by the present inventors, the most effective way to prevent roads from freezing is to include freezing point depressants in road paving materials and gradually dissolve them, but all freezing point depressants are water-soluble. As they are highly hygroscopic, they can dissolve due to moisture in the air during storage, or aggregate due to moisture absorption, so it is necessary to prevent this from occurring.As a result of studying various moisture-proofing measures, we found that the pores of hydrophobic porous particles It was found that it is very effective to store and contain the The freezing point depressant contained in the pores of hydrophobic porous particles is mixed into road paving materials and paved on the road, but as the road wears down, the porous particles are worn away or destroyed and gradually eluted onto the road surface. Although it has the effect of preventing roads from freezing, there is a problem in that the porous particles are hydrophobic and the rate of elution of the freezing point depressant contained in the pores is low because the porous particles are hydrophobic. Therefore, a means is needed to elute an effective amount of the freezing point depressant onto the road surface. However, as mentioned above, when a freezing point depressant is directly mixed into road paving materials, the hygroscopicity of the freezing point depressant tends to bring in more water than necessary into the road paving materials, which tends to reduce pavement strength. On heavy roads, it is not advisable to mix freezing point depressants directly into road paving materials. The present inventors conducted further research and found that when hydrophilic particles are mixed, the hydrophilic particles distributed along the circumference of hydrophobic porous particles containing a freezing point depressant in their pores attract water, which lowers the freezing point. The present invention was completed by discovering that the agent was well eluted. Furthermore, we are proceeding with research to increase the content of freezing point depressants, and by making hydrophilic particles distributed along the circumference of hydrophobic porous particles into porous particles, these particles also contain freezing point depressants in their pores. By doing so, we succeeded in improving the antifreeze effect even further. First, the novel freezing point depressant of the present invention will be explained. This new freezing point depressant is made from naturally occurring dolomite (a calcium and magnesium carbonate mineral).
It is a reaction product obtained by adding a mixed acid of phosphoric acid and acetic acid to and reacting with the mixture. Now, although dolomite occurs naturally, there is no pure dolomite, and its main component is double salt expressed in the form of CaCO ₃ / MaCO ₃ or Ca / Mg (CO ₃ ) ₂ . Phosphoric acid (H ₃ PO ₄ ) and acetic acid (CH ₃
When a mixed acid (COOH) is reacted, a compound having the following formal composition is obtained. MgHPO ₄・Mg (CH ₃ COO) ₂ , and CaHPO ₄・Ca (CH ₃ COO) ₂ (a small amount becomes Mg ₃ (PO ₄ ) ₂ and Ca ₃ (PO ₄ ) _2. ) This reaction product is used as a freezing point depressant in anti-freezing agents, and when a fine particle mixture containing this new freezing point depressant is added to the pavement layer, the road surface temperature decreases by -9.
It exhibits anti-freezing effect even at ℃, and has a -3
It has an excellent effect that far exceeds that of ℃. Moreover, it is easy to handle in terms of storage, manufacturing, and paving work, and does not cause deterioration in the strength of the paving layer. As will be explained in detail later, the present inventors also conducted comparative tests with the present invention on various known freezing point depressants other than common salt, such as calcium chloride and urea. Also, calcium and magnesium acetates, phosphates, and mixtures thereof were similarly tested. However, all of them had the same antifreeze function as common salt, and showed rather unfavorable results in terms of ease of handling and securing the strength of the pavement layer. The reason why the reaction product of dolomite and a mixed acid of phosphoric acid and acetic acid, which is the freezing point depressant of the present invention, exhibits excellent anti-freezing performance at -9°C is not necessarily clear academically.
The present inventors believe as follows based on the findings of the research to date. Earlier, the reaction product between dolomite and a mixed acid of phosphoric acid and acetic acid was formally expressed as MgHPO ₄ · Mg (CH ₃ COO) ₂ CaHPO ₄ · Ca (CH ₃ COO) ₂ , but in reality it is a phosphate radical (PO _4-3 ⁾
When they react together with carboxyl group (COOH ^-1 ), a "complex salt" is formed, and when it comes into contact with rain and snow and ionizes, complex ion example 1 [M(AC) ₃ ] ^- [AC = Acetate group, M = Ca, Mg]

It is thought that it forms simple PO ₄ ^-3 ,
It does not ionize to HPO ₄ ^-2 or COOH ^-1 . Although it is still not possible to completely specify the form of these complex salts and complex ions academically, considering the fact that they always give reproducible results, especially when reacting with mixed acids, complex salts are formed and this complex Ionization is considered to be an important factor in the significant freezing point lowering effect. This will be explained in detail in the performance test section below. According to experiments, a similar reaction product with the same effect can be obtained by using a mixed acid of phosphoric acid and an organic carboxylic acid having a carboxyl group other than acetic acid, such as formic acid, propionic acid, or benzoic acid. The effect is done so. Furthermore, a reaction product with similar effects can be obtained when part or all of acetic acid is replaced with a component containing a carboxyl group extracted from a natural substance such as sawdust and used as a mixed acid with phosphoric acid. A similar effect can be achieved. From this, it is understood that phosphoric acid and an organic carboxylic acid having a carboxyl group may be used together. The ratio of phosphoric acid and organic carboxylic acid having a carboxyl group to be used is preferably 1 to 10 to 1 of phosphoric acid in terms of the freezing point effect of the product. The present inventor believes that when both are used in this ratio, the formation of the above-mentioned complex salt is improved and an excellent freezing point effect is achieved. As understood from the previous explanation, in the present invention, it is sufficient to react phosphoric acid and an organic carboxylic acid having a carboxyl group with dolomite, and there is no need to use a mixed acid in which the two are mixed in advance. Needless to say. Of course, using it as a mixed acid has the advantage of simplifying the operation. As described above, one of the features of the present invention is to react dolomite, a double carbonate salt of calcium and magnesium, with phosphoric acid and an organic carboxylic acid having a carboxyl group, thereby producing a complex salt containing Ca and Mg. ”, and this “reaction product”
(hereinafter referred to as "dolomite reaction product") is used as an active ingredient of a fine particle mixture as a freezing point depressant of an antifreeze agent. Next, the composition, manufacturing method, and application to pavement of the antifreeze agent of the present invention using the novel dolomite reaction product as a freezing point depressant will be explained. Antifreeze consists of two types: hydrophobic porous particles and hydrophilic particles.
A fine particle mixture containing at least one of each of the following types of components has a particle size of approximately 0.2 mm or less, preferably 0.1 mm or less, and exhibits water repellency as a whole. A typical composition is as follows. [Hydrophilic component] A Dolomite reaction product (freezing point depressant) B Lava powder and/or quartz powder A+B 100 parts by weight [Hydrophobic component] C Calcined hydrophobic pearlite and/or foamed polyurethane D Carbon black C+D 5-75 parts by weight The outline of the basic manufacturing procedure is as follows. (1) A, B, C, and D are each manufactured and prepared in advance and stored separately. (2) Each component is taken out from the storage tank and mixed and pulverized together in a dry method to obtain a fine particle mixture having the above mixing ratio and particle size in which the pores of the porous component are filled with the freezing point depressant. During road paving, the fine particle mixture is uniformly mixed into an asphalt pavement layer at a ratio of 6 to 8%. It has excellent handling properties during pavement work, and does not adversely affect the strength, durability, etc. of the pavement. This pavement layer exhibits excellent antifreeze performance even when it snows and the road surface temperature is around -9°C. In the present invention, conventional freezing point depressants such as common salt may be used in combination as long as they do not cause any adverse effects. In the present invention, the reason why the ratio of the total hydrophobic components is set to 5 to 75 parts by weight per 100 parts by weight of the total hydrophilic components is that this range ensures that the fine particle mixture as a whole has appropriate water properties and is suitable for contact with rain and snow. This is because this range is suitable for maintaining a balance with the antifreeze function due to the elution of the freezing point depressant from the hydrophobic porous particles. Further, the particle diameter after pulverization is 0.2 mm or less, preferably 0.1 mm or less. When this fine particle mixture is mixed into an asphalt pavement layer, for example, it is easy to homogenize, there is no air entrainment, it does not cause a decrease in the strength of the pavement layer, and it also prevents freezing when exposed to the surface layer. It also functions efficiently. [Example] Next, the present invention will be specifically explained with reference to Examples,
The effects are demonstrated through comparative examples and performance tests. Example 1 70 g of 15% phosphoric acid and 400 g of 10% acetic acid were gradually added to 1000 g of dolomite (particle size 10 to 15 mm), which is a reaction product of 95% dolomite, 1% phosphoric acid, and 4% acetic acid, and mixed well. , at 110℃~150℃
The reaction is carried out with stirring in a reaction vessel for 30 to 40 minutes to obtain a dolomite reaction product. The obtained dolomite reaction product is mixed in a dry manner with a hydrophilic porous component and a hydrophobic porous component that have been manufactured or prepared in advance and stored separately in the following composition ratio. By pulverization, a fine particle mixture (antifreezing agent) with a particle size of 0.1 mm or less is obtained, in which the pores of the porous component are filled with the dolomite reaction product. Dolomite reaction product 60% by weight Lava powder 20% by weight Quartz powder 3% by weight Calcined hydrophobic pearlite 2% by weight Polyurethane foam 15% by weight Example 2 95% dolomite, 1% phosphoric acid, 4% propionic acid
reaction product, i.e. dolomite (particle size 10
~15mm) Gradually add 70g of 15% phosphoric acid and 400g of 10% propionic acid to 1000g and mix well.
The reaction is carried out at 110°C to 150°C for 30 to 40 minutes with stirring in a reaction vessel to obtain a dolomite reaction product. 60% of the obtained dolomite reaction product was combined with the porous component shown in Example 1 and subjected to dry mixing and pulverization to obtain a particle size of 0.1 in which the pores of the porous component were filled with the dolomite reaction product. Obtain a mixture of microparticles (antifreeze) smaller than mm. Comparative example a ₁ Reaction product of (95% dolomite + 5% acetic acid) a ₂ Reaction product of (95% dolomite + 5% phosphoric acid) b Common salt (NaCl) c Calcium chloride (CaCl ₂ ) d Calcium acetate (CaAC ₂ ) e Magnesium acetate (MgAC ₂ ) f Calcium phosphate (Ca ₃ (PO ₄ ) ₂ ) g Magnesium phosphate (Mg ₃ (PO ₄ ) ₂ ) h Calcium hydrogen phosphate (CaHPO ₄ ) i Magnesium hydrogen phosphate (MgHPO ₄ ) j d+e (same molar ratio) k d+e+h+i (same molar ratio) In the same manner as in Example 1, the freezing point depressants shown in a ₁ to k above were replaced with the dolomite reaction products of Example 1. Particulate mixture (antifreeze)
get. (Performance Test 1) A performance comparison test of Examples 1 to 2 and various comparative examples will be described. The performance of antifreeze agents can be judged by the frictional resistance of the pavement layer during freezing (the higher the resistance value, the better). Find and judge. (1) Preparation of test pieces Create test pieces for various comparative tests. That is, each of the 14 kinds of antifreeze agents obtained in Examples 1 to 2 and Comparative Examples and the raw material for asphalt pavement were mixed in the following standard proportions: Aggregate : 82.6% Stone powder: 2.7% Anti-freezing agent 8.0% and asphalt 6.7% total 100% are mixed, heated and blended to make an asphalt pavement material, which is finished into asphalt pavement layer test pieces with a flat surface (Sample No. 1 to Sample No. 14). (2) Test method Using the aforementioned UK-made SRT, the SRT value (skid resistance value) is measured by setting various conditions such as temperature, surface condition (wetting, drying), repeated freezing and thawing, etc. In addition, the freezing situation can be ascertained by visual inspection and tentacles. (3) Test results Typical test results are shown below. The higher the SRT value, the better the antifreeze effect.

[Table] According to the results in Table 1, there is a remarkable difference in STR value of 11 to 12 between common salt (sample No. 5) and dolomite reaction products (sample No. 1 and No. 2), and the other It's about the same as table salt, but it's quite low depending on the food. Calcium chloride has an STR value only 1 higher than that of common salt, so it is not sufficiently effective as an antifreeze agent, and has problems in storage and production due to its water repellent properties. Under freezing conditions, the dolomite reaction product according to the present invention did not form ice even at -9°C, showing significantly superior results. Dolomite was reacted with acetic acid and phosphoric acid individually (sample No. 3, No. 4), calcium acetate (sample No. 7), magnesium acetate (sample
No. 8), calcium phosphate (Sample No. 9), and magnesium phosphate (Sample No. 10), all of which had values equivalent to or significantly lower than common salt. This is significantly different from the dolomite reaction product of the present invention, which is produced by reacting both phosphoric acid and acetic acid. This is considered to indicate that the dolomite reaction product according to the present invention does not form simple phosphate ions or acetate ions, but is a complex ion-forming substance. Next, Examples 3 to 5 will be shown. Example 3 The dolomite reaction product obtained in Example 1 was
A porous component exhibiting hydrophilicity and a porous component exhibiting hydrophobicity, which have been manufactured or prepared in advance and stored separately, are combined in the following composition ratio and subjected to dry mixing and pulverization to form a porous component. A fine particle mixture (antifreezing agent) with a particle size of 0.1 mm or less is obtained, in which the pores are filled with the dolomite reaction product. Dolomite reaction product 60% Salt 1% Lava powder 20% Quartz powder 3% Calcined hydrophobic perlite 1% Polyurethane foam 15% Example 4 The dolomite reaction product obtained in Example 1 was
A porous component exhibiting hydrophilicity, a porous component exhibiting hydrophobicity, oil smoke, and cement, which have been manufactured or prepared in advance and stored separately, are combined in the following composition ratio and subjected to dry mixing and pulverization, Particle size in which the pores of the porous component are filled with dolomite reaction products
Obtain a fine particle mixture (antifreeze) of 0.1 mm or less. Dolomite reaction product 60% Lava powder 20% Quartz powder 2% Calcined hydrophobic perlite 5% Polyurethane foam 10% Oil smoke (carbon black) 1% Cement 2% Example 5 In place of 400 g of 10% acetic acid in Example 1, % acetic acid
A similar reaction is performed using 200 g of 10% propionic acid to obtain a dolomite reaction product. The obtained dolomite reaction product is combined with a hydrophilic porous component, a hydrophobic porous component, and cement, which have been manufactured or prepared in advance and stored separately, in the following composition ratio and then dry-processed. The mixture is mixed and pulverized to obtain a fine particle mixture (antifreezing agent) with a particle size of 0.1 mm or less in which the pores of the porous component are filled with the dolomite reaction product. Dolomite reaction product 62% Lava powder 21% Calcined hydrophobic perlite 6% Polyurethane foam 10% Cement 1% (Performance test 2) The antifreeze obtained in Examples 3 to 5 was added to the asphalt pavement mix aggregate 82.6% stone powder, 2.7% antifreeze, 8.0% asphalt, and 6.7% asphalt (total 100%) were each mixed into raw materials for asphalt pavement, heated and mixed to form a test piece of asphalt pavement layer with a flat surface, and sprayed with water. I checked the freezing situation. None of the test pieces formed ice at -9°C, and excellent anti-freezing effects were observed. [Effects] As mentioned above, the present invention uses a new freezing point depressant in a special way to prevent roads from freezing at temperatures as low as -9°C, which was previously impossible. Moreover, the antifreeze effect can be maintained intermittently over a long period of time, and the effect should be said to be extremely remarkable.

Claims (1)

[Scope of Claims] 1. A freezing point depressant for road anti-freezing, which contains as an active ingredient a reaction product obtained by adding phosphoric acid and an organic carboxylic acid to dolomite and reacting the mixture. 2 The ratio of phosphoric acid and organic carboxylic acid used is 1:1 ~
10. The freezing point depressing agent for road anti-freezing according to claim 1. 3 a hydrophilic particles, b calcined hydrophobic pearlite particles, expanded mica particles,
The road according to claim 1 or 2 is added to a mixture of hydrophilic particles and hydrophobic particles consisting of one or more hydrophobic porous particles selected from the group consisting of whitebait balloon particles and synthetic resin porous particles. A road anti-icing agent that contains a freezing point depressant for anti-freezing and is contained in the pores of hydrophobic porous particles. 4. The road antifreeze agent according to claim 3, wherein the hydrophilic particles are quartz powder. 5. The road antifreeze agent according to claim 3, wherein the hydrophilic particles are one or more hydrophilic porous particles selected from the group consisting of lava powder, pumice powder, and foamed glass powder. 6. The road antifreeze agent according to any one of claims 3 to 5, wherein the particle size of the mixture is 0.2 mm or less, preferably 0.1 mm or less. 7. The road antifreeze agent according to any one of claims 3 to 6, wherein the blending ratio of hydrophobic particles is 5 to 75% by weight per 100% of hydrophilic particles or quartz powder. 8 1 or 2 selected from cement and carbon powder
Any one of claims 3 to 7, wherein the above is added.
Road anti-icing agents listed in section. 9. A road paving material for preventing freezing, which is obtained by blending the freezing point depressant for road antifreezing according to claim 1 or 2 into the road paving material. 10. The road antifreeze agent according to any one of claims 3 to 8 is blended into a road paving material.
Road paving material for freezing prevention. 11. A road anti-freezing paving method, which comprises coating a road with the anti-freezing road paving material according to claim 9 or 10.