JPS6210546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a waterproof film-forming material made by mixing cement with a synthetic resin.

Conventionally, attempts have been made to mix synthetic resin emulsion or synthetic rubber latex into cement compositions, but the mixing ratio of polymer to cement is 2 to 40% as solid resin content.
% by weight (practically 5 to 20% by weight), and its main purpose was to improve the properties and performance of cement compositions, such as adhesiveness, waterproofness, and chemical resistance. Although such a method can be expected to slightly improve the properties of the cement composition, it cannot be said to be a method that actively utilizes the properties of the polymer itself.

For this reason, the present invention was created with the aim of actively utilizing the properties of the polymer itself.

Since synthetic resin emulsions use water as a medium, they have many advantages such as being free from fire hazards and toxicity, and are the most anticipated form of polymer utilization in various fields. However, compared to the case where the medium is an organic substance, the evaporation rate of water as a medium is slow, the room-temperature film forming property is lacking, and the water resistance of the formed film is low.

In order to improve the room-temperature film forming properties and water resistance, the present invention attempted to incorporate cement as a desiccant and water resistance imparting agent into the synthetic resin emulsion. Furthermore, in order to take full advantage of the flexibility, waterproofness, chemical resistance, etc. of the polymer itself, the mixing ratio of the polymer was set in the range of 45 to 200% by weight of the solid resin content relative to the cement.

When examining whether various synthetic resin emulsions could be used in the polymer cement composition targeted by the present invention, it was found that not all synthetic resin emulsions could be used.

Ca ⁺⁺ eluted from cement is currently mixed into synthetic resin emulsion or synthetic rubber latex as a modifier in cement compositions.
The chemical stability of the polymer is not destroyed by Al ⁺⁺⁺ or Al+++, and conversely, the polymer itself or the emulsifiers and stabilizers contained therein do not inhibit the hydration reaction of cement. The polymer has stability against mechanical effects such as
Properties such as not causing phenomena such as coagulation are required.

Next, the following things were found from the experimental results. In a polymer cement composition in which the mixing ratio of polymer is in the range of 40 to 200% by weight of resin solid content based on the cement, acrylic ester emulsion using a surfactant as an emulsifier, ethylene-
Vinyl acetate emulsion or styrene-butadiene-based synthetic rubber latex does not cause destructive phenomena such as coagulation of the emulsion when mixed with cement, but it does not harden even after 24 hours or more.
On the other hand, it has been found that vinyl acetate resin emulsions using polyvinyl alcohol as an emulsifier or ethylene-vinyl acetate copolymer resin emulsions solidify 15 to 30 minutes after kneading the cement and harden over time.

Therefore, it has been found that a vinyl acetate resin emulsion or an ethylene-vinyl acetate copolymer emulsion using polyvinyl alcohol as an emulsifier can be used in the polymer cement composition targeted by the present invention.

However, the film formed from vinyl acetate resin emulsion is poor in water resistance and flexibility, so its use is not preferred.

On the other hand, films formed using ethylene-vinyl acetate copolymer emulsions have excellent water resistance, alkali resistance, oil resistance, and solvent resistance, and therefore have a wide range of uses.

In addition, since ethylene is a soft component, there is no need to add a plasticizer, and the dry film has excellent flexibility, so it can be used on concrete that easily cracks, plywood that undergoes large dimensional changes due to drying and moistening, or thermal expansion. It is effective for coating substrates that require good followability, such as large iron plates.

However, a polymer cement composition consisting of two components, ethylene-vinyl acetate copolymer emulsion and cement, coagulates in 15 to 30 minutes as described above, making it difficult to use in actual sites.
Therefore, various additives were investigated in order to extend the pot life of polymer cement compositions, and the following were found to be effective.

(1) Blast furnace water slag (5-99% by weight relative to cement) (2) Gypsum dihydrate (5-90% by weight relative to cement) (3) Gypsum hemihydrate (5-90% by weight relative to cement) ) (4) Set retardant for cement mainly composed of lignin sulfonate, oxycarboxylate, etc. (0.01-2% by weight based on cement) However, among the above additives, dihydrate gypsum and hemihydrate Gypsum has poor water resistance, so their use is not recommended. Furthermore, if cement setting retarders, especially lignin-based ones, are added in large amounts, they will significantly inhibit the hydration reaction of cement, so sufficient care must be taken when adding them. The amount added is preferably in the range of 0.01 to 2% by weight based on cement.

As the synthetic resin emulsion used in the present invention, (1) ⁵ to 5
Although it is chemically stable for 60 minutes, the emulsion has the property of being destroyed and solidified after that time; (2) The materials that make up the synthetic resin emulsion do not inhibit the hydration reaction of cement; (3) The synthetic resin emulsion shall not be affected by the additives used to extend the pot life of the polymer cement composition; (4) The formed film of the synthetic resin emulsion shall have water resistance, alkali resistance, oil resistance, It is required to have excellent solvent resistance and flexibility, and to satisfy the above four conditions.

The current technology that satisfies these requirements is limited to ethylene-vinyl acetate copolymer emulsions using polyvinyl alcohol as an emulsifier and having a vinyl acetate content of 60 to 90% by weight.

It goes without saying that as the third component, an ethylene-vinyl acetate copolymer resin emulsion containing several percent of a copolymerizable unsaturated monomer can be used.

The cement used in the present invention has the property of destroying the chemical stability of the synthetic resin emulsion after the required time has elapsed, and furthermore, the setting time is extended by the inclusion of additives that retard the setting of the cement. Preferably something with properties.

Ordinary Portland cement and early-strength Portland cement are effective in the present invention, but with an alumina cement composition containing a large amount of alumina, solidification does not occur until the setting time that occurs when alumina cement undergoes a normal hydration reaction. has been confirmed by experiment. The reason for this is thought to be that, compared to Portland cement, alumina cement does not elute a large amount of Ca ⁺⁺ , which causes the destruction of emulsions. Furthermore, alumina cement is not preferred to be used because it is more expensive, has poorer water resistance, and has poorer adhesion than ordinary Portland cement.

By mixing lime such as slaked lime with alumina cement, the mixed cement causes an instant setting phenomenon, and furthermore, by mixing hemihydrate gypsum or dihydrate gypsum into the mixture, the setting time can be extended to about 20 minutes. is generally known.

Experiments have confirmed that polymer-rich films can be obtained by mixing these mixed cements with vinyl acetate resin emulsions that use water-soluble polymers as emulsifiers, or ethylene-vinyl acetate copolymer emulsions. Since the cement composition has a short pot life, it is effective for use as a rapid setting material, but this is not the intention of the present invention.

Furthermore, even if a Ca ion sequestering agent such as calcium 2-ketogluconate is added to the composition,
Experiments have confirmed that it is not possible to significantly extend the pot life.

For other types of cement that harden very quickly, if vinyl acetate resin emulsion or ethylene-vinyl acetate copolymer emulsion that uses a water-soluble polymer such as polyvinyl alcohol as an emulsifier is mixed, the emulsion will break immediately after kneading. Therefore, it is difficult to use.
Jet cement is ordinary Portland cement.
Compared to early strength cement and ultra early strength cement,
The chemical composition is high in alumina (Al ₂ O ₃ ) and sulfuric anhydride (SO ₃ ), the amount of silica (SiO ₂ ) is low, and the mineral composition is high in activated calcium aluminate. It is estimated that this causes a phenomenon.

The chemical composition of ultra-early strength cement is almost the same as that of ordinary Portland cement, only the powderiness is increased in order to exhibit early strength, so it can be applied to the polymer cement composition of the present invention. .

It goes without saying that in blast furnace cement, blast furnace water slag, which is a necessary component of the present invention, can be used in the same way since it has been mixed with ordinary Portland cement in advance.

The present invention uses polyvinyl alcohol as an emulsifier,
By mixing an ethylene-vinyl acetate copolymer resin emulsion with a vinyl acetate content of 60 to 90% by weight with Portland cement, the emulsion becomes chemically unstable due to Ca ⁺⁺ etc. leached from the cement. A polymer-rich polymer cement composition characterized by the addition of blast furnace water slag and a cement setting retarder, which have the ability to appropriately extend the breakage time of the emulsion in consideration of workability. The aim is to use this material as a waterproofing material for structures.

The reason why the present invention particularly emphasizes the adjustment of the coagulation (rupture) time of the emulsion is that it is necessary to have a sufficient pot life during application, and that it solidifies and hardens immediately after application to form a film. This is because it is an important property in construction on wet concrete surfaces, and it is also an effective means for improving water resistance.

Therefore, the composition obtained by the present invention can be applied to wet concrete surfaces, which are drawbacks of organic materials, and at the same time, since it contains a large amount of polymer, it has good waterproofness, adhesiveness, and chemical resistance. Due to its excellent properties, it can be applied as waterproofing material, coating material and adhesive.

Examples are shown below (the experiment was conducted indoors under environmental conditions of 20±2° C. and 65±5% RH).

Example 1 (comparative example) 50 parts by weight of ordinary Portland cement is mixed with 100 parts by weight of ethylene-vinyl acetate copolymer emulsion (vinyl acetate component: 80%, resin solid content: 56%) using polyvinyl alcohol as an emulsifier. As a result, a highly fluid polymer cement composition was obtained, but it solidified after 20 minutes of kneading.

Example 2 (comparative example) 50 parts by weight of ultra early strength cement for 100 parts by weight of ethylene-vinyl acetate copolymer emulsion (vinyl acetate component: 70%, resin solid content: 56%) using polyvinyl alcohol as an emulsifier. When mixed, a polymer cement composition with high fluidity was obtained, but as in Example 1, it solidified after 20 minutes of kneading.

Example 3 (Comparative Example) 50 parts by weight of ordinary Portland cement was added to 100 parts by weight each of styrene-butadiene synthetic rubber latex, acrylic synthetic resin emulsion, and ethylene-vinyl acetate copolymer emulsion using a surfactant as an emulsifier. When mixed, a highly fluid polymer cement composition was obtained, but it did not solidify even after 24 hours. It was found that the hydration reaction of cement was significantly inhibited. The solids content of the emulsions used was 45%.

Example 4 (Comparative example) 50 parts by weight of ultra-fast hardening cement was added to 100 parts by weight of ethylene-vinyl acetate copolymer emulsion (vinyl acetate component: 60%, resin solid content: 56%) using polyvinyl alcohol as an emulsifier. When mixed, the emulsion immediately coagulated abnormally and could not be kneaded. Even when 0.3% of a setting retarder for ultra-fast hardening cement was added to the same mixture as the above-mentioned mixture, abnormal setting occurred immediately after kneading.

Example 5 (Comparative Example) 50 parts by weight of commercially available alumina cement was added to 100 parts by weight of ethylene-vinyl acetate copolymer emulsion (vinyl acetate component: 80%, resin solid content: 56%) using polyvinyl alcohol as an emulsifier. When mixed, a highly fluid polymer cement composition was obtained, but it did not solidify until 3 hours or more after kneading. However, this mixture had hardened after 24 hours.

Example 6 (Comparative Example) To 100 parts by weight of ethylene-vinyl acetate copolymer emulsion (vinyl acetate component: 90%, resin solids content: 56%) using polyvinyl alcohol as an emulsifier, 25 parts by weight of ordinary Portland cement, half a When 25 parts by weight of hydrogypsum was mixed, the polymer cement composition solidified in about 45 minutes. When 0.2% by weight of citric acid was added to the cement, the solidification time was approximately 1 hour.

Example 7 (Comparative Example) To 100 parts by weight of ethylene-vinyl acetate copolymer emulsion (vinyl acetate component: 80%, resin solid content: 56%) using polyvinyl alcohol as an emulsifier, 35 parts by weight of ordinary Portland cement, When 15 parts by weight of hydrogypsum was mixed, the polymer cement composition solidified in about 30 minutes. When 0.1% and 0.3% of lignin-based cement setting retarders were added to the cement in the same formulation as the above mixture, the setting times were 45 minutes and 60 minutes, respectively.

Example 8 (Example) For 100 parts by weight of ethylene-vinyl acetate copolymer emulsion using polyvinyl alcohol as an emulsifier (vinyl acetate component: 80%, resin solid content: 56%), 25 parts by weight of ordinary Portland cement, blast furnace When 25 parts by weight of water slag was mixed, the polymer cement composition solidified in about 60 minutes. When 0.3% of an oxycarboxylic acid-based cement setting retarder was added to the cement, the setting time was approximately 80 minutes.

Example 9 (Example) For 100 parts by weight of ethylene-vinyl acetate copolymer emulsion using polyvinyl alcohol as an emulsifier (vinyl acetate component: 60%, resin solid content: 56%), 20 parts by weight of ordinary Portland cement, blast furnace When 80 parts by weight of water slag was mixed, the polymer cement composition solidified in about 60 minutes. When 0.3% by weight of an oxycarboxylic acid-based cement setting retarder was added to the same mixture as the above mixture, the setting time was approximately 90 minutes.

Example 10 A concrete block 1 measuring 300 mm x 300 mm x 50 mm (length x width x thickness) was immersed in water for 48 hours, and then placed in water 3 of tank 2 as shown in Figure 1. Next, a foam polystyrene plate 4 with a thickness of 40 mm was attached to the exposed surface of the concrete block using the polymer cement composition shown in Table 1 as an adhesive, and a tensile adhesion test was carried out after 3 days, 7 days, and 28 days. As a result, the adhesive strength shown in Table 2 was obtained. The failure state after 28 days of age all showed cohesive failure of the foam polystyrene plates.

Example 11 A film of the polymer cement composition of the formulation shown in Table 3 was made, and a dumbbell No. 3 test piece specified in the Physical Test Method for Vulcanized Rubber (JIS K 6301) was made after 7 days of age. When a tensile test was conducted using a test tube (manufactured by Shimadzu Corporation) at a test speed of 50 mm/min, the results shown in Table 4 were obtained.

Example 12 (Example) For 100 parts by weight of ethylene-vinyl acetate copolymer emulsion using polyvinyl alcohol as an emulsifier (vinyl acetate component: 60%, resin solid content: 56%), 20 parts by weight of ordinary Portland cement, blast furnace Mix 80 parts by weight of water slag and apply it to a thickness of about 1 mm on the surface of a test specimen (φ15 cm x 4 cm thick) specified in the test method for architectural cement waterproofing agents (water permeability test; JIS A1404). , and cured for 28 days at 20°C in a 65% atmosphere. Next, a water permeability test (water pressure 3Kg/cm ² /1
As a result, the water permeability ratio {=water permeability (g) of waterproofed test piece ÷ water permeability (g) of untreated test piece}) was 0.05 (2 g ÷ 38 g).

[Brief explanation of the drawing]

FIG. 1 is a longitudinal section through the test of Example 10.

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Claims (1)

[Claims] 1. An ethylene-vinyl acetate copolymer resin emulsion using polyvinyl alcohol as an emulsifier and having a vinyl acetate component content of 60 to 90% by weight has a composition of Portland cement and blast furnace slag or blast furnace cement. A waterproof film-forming material that is mixed in a proportion of not less than 200% by weight.