JPH0931434A - Freezing-stable anti-sticking adhesive - Google Patents

Abstract

(57) Abstract: An internal cross-linking monomer is added in a total amount of 100
Freeze of 0.5 to 10 parts by weight, based on 100 parts by weight of an acrylic emulsion having 0.1 to 1.0 parts by weight of copolymerized and internally crosslinked Tg of -30 ° C to 5 ° C. An anti-sticking agent that contains an inhibitor. [Effect] There is no fear of freezing at low temperatures in winter, and even if it freezes, it will easily return to its original properties by heating, the film formation speed will be fast, and a uniform film will be formed in a short time. Has a tough strength, so it also has adhesive strength between stones, water resistance, heat resistance, etc. Furthermore, it is a 1-liquid, inexpensive, etc. High practical value.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a stepping stone preventing adhesive. More specifically, the present invention relates to an acrylic emulsion excellent in freezing stability, which is sprayed for use as an anti-sticking agent for crushed stones, gravel, etc. laid on the roadbed of railroad tracks.

[0002]

2. Description of the Related Art Conventionally, a railroad track has been laid with a ballast such as crushed stone or gravel, which is commonly called ballast, and sleepers have been laid on it to run rails. In recent years, as the speed of railway vehicles has increased, flying stones due to wind pressure when passing trains and ice blocks containing stones adhere to the underfloor of the train in the winter, which suddenly fell during operation due to rising temperatures, causing human injury. The danger of connection was a problem.

As a solution to these problems, there is a method of converting concrete to asphalt without using the track structure itself or crushed stone. As described in a method of covering the road surface with a flying stone prevention net, or as described in, for example, JP-A-4-296385, JP-A-52-16810, JP-A-49-32306, synthetic rubber latex or synthetic resin emulsion is added to the ballast. Aqueous emulsion such as, polyester resin, epoxy resin,
Reactive resins such as urethane resins, asphalt emulsions and the like, alone or in combination of several kinds, and resins in which inorganic substances such as cement are further mixed, have been sprayed by rain or spray using a spray applicator or the like.

[0004]

When the above-mentioned aqueous emulsion system is used, the construction cost is low, but as a drawback of the aqueous emulsion, freezing in winter work is a major problem, and at the time of low temperature. The glass transition temperature (hereinafter abbreviated as Tg) is designed to be 0 ° C. or lower in order to improve the film forming property of, and the cohesive force of the resin itself is low, so that the binding force (adhesive force) between stones is low. There were problems such as easy disconnection due to repeated vibrations when passing trains, problems that did not form a film until the first train passed, and environmental pollution problems such as undried emulsion flowing out in rainwater. A technique has been proposed in which a curing agent such as an epoxy resin, a urethane resin, and a metal salt is used in combination with the emulsion for the purpose of improving these drawbacks, but it is more practical than the problems such as the complexity of the two-liquid mixing operation and the stability of the mixture. The achievement record is extremely low. Regarding the above-mentioned reactive resin and asphalt emulsion, construction is expensive, it is difficult to construct with high viscosity, odor pollution, there is a problem that the curing rate is significantly reduced in winter, etc. there were. In addition, the inorganic compound resin represented by cement in these compounds is difficult to control the curing rate, and the film after curing is hard and lacks in impact resistance, and the bond is broken by the vibration during train passage, resulting in an extremely short period of time. There was a problem that the effect disappeared.

[0005]

[Means for Solving the Problems] An aqueous emulsion that is advantageous in terms of construction cost and imparts freeze stability, which is a drawback of the aqueous emulsion, and has a Tg of 0 ° C. or less from the viewpoint of film formation of the emulsion in winter. Even in this case, as a result of earnestly studying to provide a binding force between stones, Tg
The internally cross-linked acrylic emulsion having a temperature range of -30 ° C to 5 ° C has excellent film-forming properties in winter, and it is necessary to add an antifreezing agent that does not impair the film-forming property to the freezing-stabilized stepping stone. They have found that they are extremely effective as an anti-sticking agent and have completed the present invention.

That is, the present invention provides the following (1) and (2)
It is as follows. (1) 0.5 to 10 parts by weight of an antifreezing agent is added to 100 parts by weight of an acrylic emulsion having a glass transition temperature of −30 ° C. to 5 ° C. and internally crosslinked with an internal crosslinking monomer. Characteristic flying stone prevention adhesive. (2) The sticking agent for flying stone prevention according to (1), wherein the internal cross-linking monomer is used in an amount of 0.1 to 1.0 part by weight based on 100 parts by weight of the total amount of the monomers.

BEST MODE FOR CARRYING OUT THE INVENTION

The acrylic emulsion internally crosslinked with an internal crosslinking monomer having a Tg of -30 to 5 ° C. according to the present invention is:
Aromatic vinyl-based monomers and unsaturated carboxylic acid ester monomers are the main components, and acrylic monomers having hydroxyl groups, acrylic monomers having amide groups, monomers having carboxyl groups, and internal crosslinking monomers are copolymerized, resulting in low Tg. The film formed means an acrylic emulsion having a strong strength despite the low film temperature. Examples of the aromatic vinyl-based monomer include styrene, α-methylstyrene, acrylonitrile, vinyl acetate and the like, and examples of the unsaturated carboxylic acid ester monomer include methyl acrylate, methyl methacrylate, ethyl acrylate and i-butyl. Examples thereof include methacrylate, tert-butyl methacrylate, i-butyl acrylate, n-butyl acrylate, 2 ethylhexyl acrylate, 2 ethylhexyl methacrylate and lauryl methacrylate.

Examples of the acrylic monomer having a hydroxyl group include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and the like, and examples of the acrylic monomer having an amide group include acrylamide, methacrylamide, maleimide, N-methylolacrylamide. Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic acid and fumaric acid. Further, examples of the internal crosslinking monomer include divinylbenzene and acrylic monomers having a glycidyl group, and divinylbenzene is preferable as the monomer effective for improving the crosslinking density with a small amount of copolymerization.

The Tg of the acrylic emulsion internally crosslinked with the internal crosslinking monomer of the present invention is in the range of -30 ° C to 5 ° C. It is preferably in the range of -20 ° C to 0 ° C. -3
If the temperature is lower than 0 ° C, it is difficult to increase the strength of the formed film itself even if the above-mentioned internal cross-linking monomer is copolymerized.
Insufficient heat resistance. If it exceeds 5 ° C, a problem occurs in the film forming property at low temperatures in winter, and it becomes difficult to form a uniform film, and the desired adhesive strength cannot be obtained. Further, in order to improve the film forming property at low temperature, when a polyhydric alcohol derivative typified by commonly used ethyl cellosolve, butyl cellosolve, butyl carbitol, etc., or a petroleum residue is blended, Although it is effective in forming a film, the object of the present invention cannot be achieved because the film forming rate is significantly reduced.

The copolymerization ratio of the internally crosslinked monomer used in the acrylic emulsion of the present invention, which is internally crosslinked, is in the range of 0.1 to 1.0 parts by weight, preferably 0.2 parts by weight, based on 100 parts by weight of the total amount of the monomers. By using ~ 0.5 parts by weight, the crosslink density is increased and the toughness of the formed film is imparted. When the copolymerization ratio is less than 0.1 parts by weight, the toughness of the film formed cannot be expected to be improved, and the adhesive strength is low and the object of the present invention cannot be achieved. If it exceeds 1.0 part by weight, there is a high risk of gelation during emulsion synthesis, and the film formed is too hard to easily cause brittle fracture by applying a light impact, and the object of the present invention cannot be achieved.

Examples of the antifreezing agent of the present invention include lower alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, polyhydric alcohols such as ethylene glycol and derivatives thereof, and sodium chloride as an inorganic system. In order to obtain the antifreezing effect without impairing the film formation rate at low temperatures in winter, a combination of two or more of these is preferable, and a combination of methyl alcohol and ethylene glycol is particularly preferable. The content of the antifreezing agent is 0.5 to 10 parts by weight based on 100 parts by weight of the acrylic emulsion internally crosslinked with the internal crosslinking monomer.
It is in the range of parts by weight. A range of 3 to 6 parts by weight is preferred.

When the amount is less than 0.5 parts by weight, the antifreezing effect is low, and when the amount is more than 10 parts by weight, problems such as stability during storage and risk of ignition occur. As above, Tg is -30 ℃
An anti-freezing agent mixed with an acrylic emulsion internally cross-linked by copolymerization of internal cross-linking monomers at ~ 5 ° C does not cause freezing at low temperatures in winter, and even if frozen It easily returns to its original properties due to the temperature,
It forms a uniform film in a short time with a fast film formation rate, and has strong film formation strength, so it also has stone-to-stone adhesion, water resistance, heat resistance, etc. It has high practical value as an adhesive agent for preventing flying stones due to its superior properties such as low cost and low cost.

[0013]

EXAMPLES In order to explain the present invention more specifically,
The production examples, examples, and comparative examples will be described, but the present invention is not limited to these examples. In the following, parts or% are based on weight unless otherwise specified.

Production Examples 1 to 5 Mixing monomers in the proportions shown in Table 1 were prepared as a pre-emulsified monomer by dropping under forced stirring in 0.5 part of sodium dodecylbenzenesulfonate dissolved in 50 parts of distilled water. did. Separately, 100 parts of distilled water and 0.3 part of sodium dodecylbenzenesulfonate were charged into a 1 liter flask, and the temperature was raised to 85 ° C. under a nitrogen stream, and then 0.5 parts of potassium persulfate and the core of the emulsion were prepared. A mixed monomer having a mixing ratio of n-butyl acrylate / methyl methacrylate / hydroxyethyl acrylate of 1/1/1 was administered and reacted at the same temperature for 20 minutes to form a core of the acrylic emulsion of the present invention.

Then, the pre-emulsified monomer is continuously added dropwise over 3 hours, after the completion of the addition, the residual monomer is reacted at the same temperature for 3 hours and then cooled to 40 ° C. or lower, and the pH is adjusted to 7 with 14% ammonia water. The mixture was adjusted and filtered through a 100-mesh wire mesh to obtain the internally crosslinked acrylic emulsion of the present invention.
By the way, this emulsion has a solid content of 40% and a viscosity of 100.
cps (BM type rotational viscometer / manufactured by Tokyo Keiki Co., Ltd.) and average particle size 80 nm (submicron particle analyzer / manufactured by Nozaki Sangyo Co., Ltd.).

Examples 1 to 9 The antifreezing agent shown in Table 2 was added to 100 parts by weight of the internally crosslinked acrylic emulsion of the present invention obtained in Production Examples 1 to 5, and the mixture was subjected to the following tests and evaluated. The results are shown in Table-3.

Evaluation Test 1) Freeze Stability Test The formulations obtained in Examples 1 to 9 were taken in 500 cc polyethibin and allowed to stand in a thermostatic chamber at -10 ° C. for 24 hours. displayed. If freezing is further confirmed, dip it in a constant temperature bath at 40 ° C for 1 hour, visually observe whether it returns to the original emulsion on the appearance, and further filter with a 100 mesh wire mesh to check for residue and check as shown below. displayed. a) Presence / absence of freezing × Partially frozen or viscosified △ Not frozen × 2) Adhesive strength of mortar As an alternative to stone, manufactured by Nippon Test Panel Co., Ltd., vertical × horizontal ×
100 g / m ² of the acrylic emulsion of the present invention was applied to the thickness side of a JIS mortar of thickness = 70 × 70 × 20 mm, and immediately another mortar was laminated, and the mortar was kept at room temperature for 1 hour.
After curing for a week, the tensile strength was measured with an Intesco tensile tester at a pulling speed of 50 mm / min (Kg / c
m ² ).

3) Dryability A wire net is laid on the bottom 20 mm of a polyethylene cup having a diameter of 150 mm and a depth of 200 mm, and about 50 is placed on the wire net.
Crushed stones of mm square were spread to a thickness of 150 mm, the acrylic emulsion of the present invention was sprayed with rain and dew in a constant temperature room of 5 ° C., and the dried state of the crushed stone surface after visually standing for 1 hour in the same room was visually observed and displayed as shown below. . ○ Transparent film formation △ Partly undried × Not fully dried 4) Impact resistance The crushed stone bonded body prepared in 2) above was aged at room temperature for 1 week and dropped from a height of 500 mm to destroy crushed crushed lumps. Displayed in number. A large number indicates a lack of impact resistance.

Comparative Example 1 The antifreezing agent was removed from Example 1, the same test as in Example 1 was carried out, and the results are shown in Table-5. Comparative Example 2 The amount of the antifreezing agent of Example 1 was increased 2.5 times at the same ratio, and the same test as in Example 1 was performed below. The results are shown in Table-5. Comparative Example 3 The antifreeze agent of Example 2 was reduced to 1/2 amount at the same ratio, and the same test as in Example 1 was performed below. The results are shown in Table-5. Comparative Examples 4 and 5 Acrylic emulsions were synthesized with the monomer compositions shown in Table 4 according to the production examples and subjected to the same tests as in Example 1 and the results are shown in Table 5.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

[Table 5]

[0025]

As shown in Table 3 and Table 5, the Tg
The anti-sticking adhesive compounded with an anti-freezing agent in an acrylic emulsion internally cross-linked by copolymerization of an internal cross-linking monomer at -30 ° C to 5 ° C does not have a risk of freezing at low temperatures in winter, and should be frozen. Even if it is heated, it will easily return to its original properties, the film formation speed will be fast, and a uniform film will be formed in a short time. It also has strength, water resistance, heat resistance, etc., and it is highly practical as a stepping stone prevention adhesive because of its superiority such as being one-liquid and inexpensive.

Claims (2)

[Claims] 1. An acrylic emulsion 1 having a glass transition temperature of -30 ° C. to 5 ° C. and internally crosslinked with an internal crosslinking monomer.
A sticking agent for preventing flying stones, characterized in that 0.5 to 10 parts by weight of an antifreezing agent is mixed with 100 parts by weight. 2. An internal cross-linking monomer is added in a total amount of 100
The adhesive for preventing flying stones according to claim 1, which is used in an amount of 0.1 to 1.0 parts by weight based on parts by weight.