JPH0931432A - Stepping stone prevention adhesive - Google Patents

Abstract

(57) [Summary] A glass transition temperature (Tg) is -30 ° C to 5 ° C.
This is an acrylic emulsion of 0.1 to 1.0 parts by weight with respect to 100 parts by weight of the total amount of the monomers, and the amount of toluene eluted is less than 20%, and the tensile strength of the film is the highest. 50 to 150 in breaking strength
An adhesive for preventing flying stones, which is an acrylic emulsion internally cross-linked and has a weight of Kg / cm ² . [Effect] The internally crosslinked acrylic emulsion of the present invention has an excellent binding force in adhering stones even though the Tg is set low in consideration of the film forming property at low temperature in winter. With impact resistance, it is highly useful as a sticking agent for preventing crushed stones or gravel laid on railway lines.

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 that is sprayed for use as an anti-sticking agent for flying stones, such as crushed stones and gravel laid on the roadbed of railway lines.

[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 cars 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, concrete or asphalt is formed without using the track structure itself or crushed stone. A method of covering the road surface with a flying stone prevention net, for example, JP-A-4-296385 and JP-A-52-16810.
And Japanese Patent Application Laid-Open No. 49-32306,
An aqueous emulsion such as synthetic rubber latex or synthetic resin emulsion, reactive resin such as polyester resin, epoxy resin, urethane resin, asphalt emulsion, etc., alone or in combination with several kinds of ballast, and inorganic substances such as cement. The blended resin was sprayed using rain or dew or a spray coater.

[0003]

When the above-mentioned aqueous emulsion system is used, the glass transition temperature (hereinafter abbreviated as Tg) is set in order to improve the film forming property in the winter, though the construction cost is low. Due to the fact that it is designed to be 0 ° C or less, the cohesive force of the resin itself is low, so the stones have a low binding force (adhesive force), and the problem of easy disconnection due to repeated vibrations when passing trains and application with rainwater There was a problem that the emulsion film was whitened and the binding strength was significantly reduced.

In order to improve these drawbacks, a technique of using a curing agent such as an epoxy resin, a urethane resin or a metal salt in the emulsion has been introduced, but the two-component mixing operation is complicated and the mixture is stable. Due to problems such as sex, the actual practical use is extremely low. For the above-mentioned reactive resin and asphalt emulsion, construction is expensive, it is difficult to construct due to high viscosity,
There are problems such as a strong odor and a significant decrease in the curing rate in winter, and the above-mentioned several types of blended products also had the same problems. 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 was reduced.

[0005]

[Means for Solving the Problems] As a result of intensive studies to solve the above problems with an aqueous emulsion which is advantageous in terms of construction cost and also with a one-pack type emulsion, as a result, Tg of -30 to 5 was obtained from the film forming property in winter. In the range of 0 ° C., the decrease in the cohesive force of the formed film due to the decrease in Tg, that is, the decrease in the bond strength between stones, is achieved by internally crosslinking the aqueous emulsion by copolymerizing an internal crosslinking monomer, The present invention has been completed by discovering that it is a one-liquid type but exhibits a high cohesive force and is extremely effective as a sticking agent for preventing flying stones.

That is, the present invention is as follows (1) to (4). (1) An adhesive agent for preventing flying stones, characterized in that it comprises an internally crosslinked acrylic emulsion having a glass transition temperature of -30 ° C to 5 ° C. (2) The sticking agent for preventing flying stones according to (1), wherein the internal crosslinking 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 monomers. (3) The adhesive for preventing flying stones according to (1), wherein the amount of toluene eluted from the internally crosslinked acrylic emulsion film is less than 20%. (4) The tensile strength of the internally crosslinked acrylic emulsion film is 50 to 150 at the maximum strength at break.
An adhesive for preventing flying stones according to (1), which has a Kg / cm ² range.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic emulsion of the present invention includes an aromatic vinyl monomer, an unsaturated carboxylic acid ester monomer as a main component, an acrylic monomer having a hydroxyl group, an acrylic monomer having an amide group, and a monomer having a carboxyl group. The film formed by the copolymerization of an internal cross-linking monomer has a low Tg and a low film forming temperature, but the film thus formed means an acrylic emulsion having a strong strength.

Examples of aromatic vinyl monomers include styrene, α-methylstyrene, acrylonitrile, vinyl acetate, and the like, and examples of unsaturated carboxylic acid ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, i- Examples thereof include butyl 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 internally crosslinked acrylic emulsion 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. If the temperature is lower than -30 ° C, the film-forming film itself, even if the above-mentioned internal crosslinking monomer is copolymerized,
It is difficult to increase the strength, resulting in insufficient adhesive strength and heat resistance. If it exceeds 5 ° C, a problem occurs in the film forming property in winter, and it becomes difficult to form a uniform film, and the desired adhesive strength cannot be obtained.

The copolymerization ratio of the internal crosslinking monomer of the present invention is 0.1 to 1.0 based on 100 parts by weight of the total amount of the monomers.
It is in the range of parts by weight, and preferably 0.2 to 0.5 parts by weight is used, whereby 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.

In the internally crosslinked acrylic emulsion of the present invention, the amount of toluene eluted from the formed film is less than 20%. Preferably it is in the range of 5 to 10%. This elution amount serves as a measure of the degree of internal cross-linking of the acrylic emulsion by the above-mentioned copolymerization of divinylbenzene. When it exceeds 20%, the degree of cross-linking is low and thus the adhesive strength is low and the object of the present invention cannot be achieved. In the internally crosslinked acrylic emulsion of the present invention, the tensile strength of the film formed is in the range of 50 to 150 Kg / cm ² at the maximum breaking strength. It is preferably in the range of 80 to 120 Kg / cm ² . 50K
If it is less than g / cm ² , the desired adhesive strength cannot be obtained,
If it exceeds 0 Kg / cm ² , it is too hard and lacks impact resistance, and the object of the present invention cannot be achieved.

By combining the above monomers, Tg
Since the stepping stone preventing adhesive composed of an internally cross-linked acrylic emulsion having a temperature of −30 ° C. to 5 ° C. has a film-forming property at low temperatures in winter and has a tough film-forming strength. , Stone-to-stone adhesion, water resistance, heat resistance,
Excellent impact resistance and extremely high practical value.

[0014]

EXAMPLES In order to explain the present invention more specifically,
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.

Examples 1 to 7 The mixed monomers in the proportions shown in Table 1 were prepared as a pre-emulsified monomer by dropwise addition 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 0.2 part of sodium dodecylbenzenesulfonate were charged into a 1 liter flask, and the temperature was raised to 70 ° 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.

Next, 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, average particle size 150 nm.

Further, this emulsion was treated at 20 ° C. and 65%
A 1 mm thick uniform film was formed on a glass plate in a humidity-controlled room, and the physical properties of the film formed after curing for 1 week were measured by the following methods. The results are shown in Table 1. a) Toluene elution amount The film formed was cut into a 5 × 5 cm square, weighed, placed in a 300 cc Erlenmeyer flask containing 100 g of toluene, immersed at room temperature for 24 hours, and then filtered through a 300 mesh wire mesh. A part of the filtrate is weighed and dried in a hot air dryer at 105 ° C for 2
After drying for a period of time, the residue was weighed, the elution concentration was calculated, and the elution amount relative to the weight of the initial film-forming film was calculated and expressed as (%). b) Tensile strength measurement The film-formed film was cut into a sample for a tensile test with a No. 2 dumbbell, and 50 m using an Intesco tensile tester.
The tensile strength was measured at a tensile speed of m / min, and the strength (Kg / cm ² ) at maximum breaking was displayed.

The internally crosslinked acrylic emulsions of the present invention obtained in Examples 1 to 7 were subjected to the following tests, and the evaluation results are shown in Table 2. 1) Adhesive strength of mortar As an alternative to stone, manufactured by Nippon Test Panel Co., Ltd., vertical x horizontal x
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 ). 2) 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 a wire net of 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 3) 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 lumps of crushed stone. Displayed in number. A large number indicates a lack of impact resistance.

[0019]

[Table 1]

[0020]

[Table 2]

Comparative Examples 1 to 5 Acrylic emulsions having the monomer compositions shown in Table 3 were produced in the same manner as in Examples, and evaluated in the same manner as in Examples, and the evaluation results are shown in Table 4.

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

As is apparent from Tables 2 and 4, the Tg of the internally crosslinked acrylic emulsion of the present invention is set low in consideration of the film forming property at low temperatures in winter. , It has excellent bond strength and impact resistance in adhering stones, and is highly useful as a sticking agent for preventing crushed stones or gravel stones laid on railway lines.

Claims (4)

[Claims] 1. An adhering agent for preventing flying stones, which comprises an internally crosslinked acrylic emulsion having a glass transition temperature of −30 ° C. to 5 ° C. 2. The stepping stone preventing adhesive according to claim 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. 3. The stepping stone preventing adhesive according to claim 1, wherein the amount of toluene eluted from the internally crosslinked acrylic emulsion film-forming film is less than 20%. 4. The tensile strength of the internally crosslinked acrylic emulsion film is 50 to 50 at the maximum strength at break.
The flying stone preventing adhesive according to claim 1, which has a range of 150 kg / cm ² .