JPS5930666B2 - water repellent composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to water-repellent compositions.

Specifically, the present invention relates to a composition that imparts water repellency to building materials by drying at low temperatures.

Conventionally, products using plaster, such as plasterboard, lath board, decorative board, and sound-absorbing board (hereinafter collectively referred to as boards), have divine characteristics due to the characteristics of plaster.
On the other hand, it has the tendency to easily absorb water and become brittle.

Therefore, despite the remarkable characteristics of gypsum-based building materials such as fireproofing properties, soundproofing properties, strength, and low prices, the range of use of gypsum-based building materials is currently limited.

Boards using gypsum as described above usually consist of a core containing gypsum and base paper on both sides of the core.

In the past, various experiments have been conducted to make boards water resistant.
The following methods have been proposed.

(1) One or both sides of the board are covered with a hydrophobic material, such as cloth,
Cover with paper, etc.

(2) Apply a water repellent such as paraffin, metal soap, or siamite to one or both sides of the board.

(3) Cover the surface of the board with a water-impermeable film.

(4) A water repellent as described in 2) above is mixed into the core.

However, as shown in (1) and (2), the water resistance of the board may be incomplete depending on the application or coating of hydrophobic substances or water repellents, making it extremely difficult to install in practice.

In the case of (3), the board can be provided with sufficient water resistance, but when the board is cut and used, the cut surface cannot be provided with sufficient water resistance.

Furthermore, it is necessary to add decorations to the surface of the board, resulting in high costs.

Furthermore, regarding (4), although it is possible to improve water resistance,
Adhesion between the base paper and the core is poor, making it impractical.

Furthermore, it is difficult to use conventionally known hydrophobic substances and water repellents.

In addition, conventional water-resistant boards are generally inferior to general-purpose boards in terms of physical properties, particularly board strength and adhesion between the core and base paper, and when water is absorbed, the above-mentioned physical properties deteriorate significantly.

Therefore, it has sufficient water resistance so that it can be used as interior and exterior materials for areas that come into contact with water, such as roof bases and water areas, and it is easy to work with when manufacturing boards, and post-processing is also possible. Therefore, it has been desired to create a board that is also satisfactory in terms of the above-mentioned physical properties.

As a result of intensive research aimed at creating a board that satisfies all of the above points, the inventors of the present invention have found that a paraffinic hydrocarbon emulsion using a nonionic surfactant and an emulsion polymer using a nonionic surfactant are simultaneously mixed into a gypsum slurry. The present inventors have discovered that when added to the base paper, a remarkable synergistic effect appears on the water resistance, the physical properties are also improved, and the adhesion between the core and the base paper is improved, and the present invention has been achieved.

That is, the gist of the present invention is (a) a melting point of 40°C to 80°C;
An emulsion in which a paraffinic hydrocarbon (hereinafter referred to as paraffin) is emulsified with a nonionic surfactant; and (a)
The water-repellent composition contains the solids in the component to the solids in the component (b) in a weight ratio of 2:8 to 8:2.

In addition to boards, the composition of the present invention can be widely used as a water repellent for cement, building materials, etc., but it gives particularly good results when used for boards.

The present invention will be explained in detail below.

In the present invention, it is necessary to use paraffin having a melting point of 40°C to 80°C as a water repellent.

If the melting point of paraffin is lower than 40°C, deterioration of the quality of the board will occur in summer.

If the melting point of the paraffin is higher than 80°C, it is not preferable because the drying temperature of the board will be 80°C or higher and a board with good water resistance will not be obtained.

It is well known that when boards are dried at high temperatures, the gypsum dehydrates and deteriorates, reducing its water resistance.
This is because it is preferable to dry at a temperature of °C or lower.

The nonionic surfactant used for emulsifying paraffin is not particularly limited, and any known nonionic surfactant can be used.

Specifically, for example, ether derivatives of polyalkylene glycol such as polyethylene glycol lauryl ether, polyethylene glycol nonylphenyl ether, polyphenylpheptyrene glycol polyethylene glycol ether, polyalkylene glycols such as polyethylene glycol monolaurate, polyethylene glycol monostearate, etc. sorbitan fatty acid esters such as sorbitan monostearate, polyoxyalkylene turbicun fatty acid esters such as polyoxyethylene sorbitan monolaurate, and mixtures thereof.

These nonionic surfactants are usually paraffin 100
It is used in an amount of 5 to 20 parts by weight.

To emulsify paraffin with a nonionic surfactant, any of the well-known mechanical emulsification methods, phase inversion emulsification methods, etc. can be used, and a combination of these methods is also possible.

Mechanical emulsification methods include a homomixer, a bulb homogenizer, a colloid mill, an ultrasonic method, and the like, and in the present invention, any method can be used as long as it can produce a uniform paraffin emulsion.

On the other hand, when using the phase emulsification method, the selection of the emulsifier during phase inversion is important, but by using a nonionic surfactant, a paraffin emulsion suitable for the composition of the present invention can be obtained.

There is no particular restriction on the particle size of this paraffin emulsion, but from the viewpoint of stability of the paraffin emulsion, it is desirable that the particle size of the paraffin in the paraffin emulsion is 10 μm or less.

Furthermore, in the present invention, it is necessary to use an emulsion polymer having a minimum film forming temperature of 80° C. or lower as the water repellent reinforcing agent.

Particularly preferably, one having a minimum film formation temperature of about room temperature is used.

Examples of emulsion polymers include acrylic ester-based and vinyl ester-based emulsion polymers, and specifically, acrylic esters such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, and homogeneous monomers such as vinyl acetate. Emulsion polymers consisting of polymers and copolymers can be used.

Furthermore, by adding a portion of a self-crosslinking modified emulsion polymer to the above emulsion polymer, the physical properties of the board can be improved.

Emulsion polymers with a minimum film-forming temperature exceeding 80°C will not form a film if the board is dried below 80°C, and the board will not have sufficient water resistance. If drying is carried out at a temperature higher than 0.degree. C., the gypsum itself will deteriorate due to dehydration, as described above, and its water resistance will deteriorate.

Here, the term "minimum film-forming temperature" means the lowest temperature necessary for an emulsion polymer having film-forming ability to form a film, and has the same meaning as commonly used in the industry.

When producing emulsion polymers, they are emulsified with nonionic surfactants.

As the nonionic surfactant, the same nonionic surfactant as used for emulsifying paraffin as described above can be used.

Furthermore, polyvinyl alcohol or the like can also be used as a protective colloid.

The amount of nonionic surfactant used is usually 1 to 10 parts by weight per 100 parts by weight of the emulsion polymer raw material.

Emulsion polymers are produced by emulsion polymerization of raw material monomers using a general water-soluble polymerization initiator in the presence of a nonionic surfactant.

Any commonly used water-soluble polymerization initiator can be used without particular restrictions, and specifically, oxidizing agents such as potassium persulfate, ammonium persulfate, and hydrogen peroxide, and these together with L-ascorbic acid, Roncalitto,
Redox catalysts in combination with organic or inorganic reducing agents such as acidic sodium sulfite and ferrous chloride can be used.

In the water-repellent composition of the present invention, the weight ratio of solids in the paraffin emulsion to solids in the emulsion polymer produced as described above is 2:8 to 8:2, preferably 4:6.
They are used in a mixed ratio of ~6:4.

Outside this range, a sufficient mutual effect of the two cannot be obtained.

Although the cause is not clear, the inventors of the present invention think as follows.

That is, the paraffin particles in the paraffin emulsion are
When the volume is constant, it becomes a sphere with the minimum surface area, and the emulsifier is considered to be attached to the surface.

When an emulsion polymer is added to this and dried, when the polymer in the emulsion polymer forms a film, the paraffin particles are deformed and flattened, so the surface area of the paraffin particles increases and the paraffin parts that are not covered with the emulsifier appears, and it is thought that this area exhibits a water-repellent effect.

Note that the solid content in the paraffin emulsion and emulsion polymer refers to the solid content obtained by heating the paraffin emulsion and emulsion polymer according to a conventional method to remove water and other volatile components from each.

There are no particular limitations on the mixing of the paraffin emulsion and the emulsion polymer, and it is sufficient to mix each component before using it as a water repellent, but it is desirable to mix each component uniformly in advance.

Next, a typical method of using the water repellent composition of the present invention is as follows.
The case where it is used for manufacturing a board will be explained.

First, in order to make the core of the board, the water repellent composition of the present invention produced as described above is mixed with calcined gypsum alone or mainly with calcined gypsum, and if necessary, perlite, glass fiber, asbestos, pumice, etc. It is manufactured by adding vermiculite, a setting rate regulator for gypsum, etc. to a mixture with water, curing and drying.

The water repellent composition of the present invention has a solid content of 100% calcined gypsum.
Usually 2 to 20 parts by weight, preferably 2 to 15 parts by weight
Add in parts by weight.

If the solid content is less than the above range, a sufficient effect will not be achieved, and if it is more than the above range, the flame resistance and economic efficiency, which are the characteristics of the board, will be lost, which is undesirable.

Further, the amount of water to be added to the above-mentioned calcined gypsum and mixture thereof may be a well-known amount, and if the amount of water alone in the water repellent composition of the present invention is insufficient, additional water may be added. may be added to adjust the amount of water mixed with calcined gypsum and mixtures thereof.

Stirring, casting, and drying of the gypsum slurry to which the water repellent composition of the present invention has been added can be performed using methods commonly used in the art for manufacturing boards, and gypsum boards can be easily manufactured.

It goes without saying that it can also be used for so-called foamed gypsum in which the apparent specific gravity of the board core is 0.7 or less.

The present invention has the following effects due to the features detailed above.

First, compared to when paraffin emulsion or emulsion polymer is added alone or in combination with other water repellents, significantly higher water resistance can be obtained due to the mutual effect when both are added at the same time.

Secondly, compared to the case where the water repellent composition of the present invention is not used, when the water repellent composition of the present invention is used, the physical properties when wet are good and the water resistance is high.

Thirdly, it has better physical properties such as water resistance, strength, and workability than conventional water repellents, especially asphalt-based water repellents that are considered suitable for boards. .

Fourth, compared to using conventionally known water repellents,
Good adhesion between base paper and core, no peeling.

The present invention will be further explained below using Examples, but the present invention is not limited by the Examples unless the gist of the invention is exceeded.

In the examples, "part" means 1 part by weight.

Reference Example 1 Preparation of water repellent i) Paraffin emulsion a A flask containing the following raw materials was heated to 70°C, and 200 parts of deionized water was added dropwise while stirring vigorously with a homomixer, phase inversion was performed, and the mixture was heated for 30 minutes. A paraffin emulsion was obtained in the entire time required.

100 parts of paraffin with a melting point of 57°C 4.4 parts of sorbitan monostearate 5.6 parts of polyoxyethylene sorbitan monostearate related.

Reference Example 2 Preparation of Water Repellent Auxiliary Agent 1) Emulsion Polymer A The following raw materials were placed in a 300 d four-loaf flask equipped with a stirrer, and heated to 50°C in a nitrogen atmosphere while stirring at 300 rpm.
Polymerization was carried out for 6 hours.

Deionized water 100 parts Methyl methacrylate 30 parts n-butyl acrylate 70 parts Potassium persulfate
0.5 parts Polyoxyethylene sorbitan monostearate 1-2.5 parts Polyethylene glycol monolaurate 2.5 parts Sodium bisulfite 0.1 part 11) Emulsion polymer B Emulsion polymer A and the following raw materials were substituted. An emulsion polymer was prepared in exactly the same manner.

Deionized water 100 parts Vinyl acetate - 100 parts Potassium persulfate 0.2 parts Polyvinyl alcohol 2 parts Polyoxyethylene sorbitan monostearate 2.8 parts Sodium hydrogen carbonate 0.4 parts Paraffin emulsion a of Reference Examples 1 and 2 , water repellent, and emulsion polymers A and B all had good stability.

The solid content in each is paraffin emulsion a
33% water repellent b 60% emulsion polymer A 50% B 50%.

Furthermore, the minimum film formation temperature for both emulsion polymers A and B was about 10°C.

Example 1 Paraffin emulsion a1 prepared in Reference Example 1-i)
20.5 parts were added together with 80 parts of emulsion polymer A prepared in Reference Example 2-1) to a mixed slurry consisting of 800 parts of Sakura A grade calcined gypsum manufactured by Yoshino Gypsum Co., Ltd. and 519 parts of deionized water. After stirring thoroughly and uniformly, pour it into a mold.
It was dried at 30 to 40°C and used as an evaluation sample.

In addition, the water resistance test sample and the sample for evaluating the adhesion between the base paper for gypsum board and the core were made of a core and the base paper for gypsum board on both sides.For the bending property test, the base paper for gypsum board was used. First, only the core was sampled.

The water resistance test of the sample was carried out by placing the sample in water at 20℃ for 1 hour.
The sample was immersed for a period of time and the change in weight of the sample was measured.

In the bending property test upon water absorption, the sample was immersed in water at 20° C. for 2 hours, and the bending strength was directly measured in accordance with JISA-6904.

Furthermore, the adhesion test between base paper for gypsum board and core was conducted by J.
It was carried out in accordance with ISA-6901.

These results are shown in Table 1.

From these results, it was found that the gypsum board using the water-repellent composition of the present invention has a significant difference compared to the comparative example in not only water resistance but also physical properties upon water absorption and adhesion between the core and base paper. I understand.

Incidentally, a scanning electron micrograph (magnification: 3000 times) of the fractured surface of the sample is shown in FIG.

This photo shows that the acicular crystals of gypsum dihydrate are growing well.

Examples 2 to 5 Example 1 except that the water-repellent composition having the composition shown in Table 1 was used.
Samples were manufactured and tested exactly as required.

The amount of water mixed with the calcined gypsum was adjusted so that the sum of the water in the water-repellent composition of the present invention and the additional deionized water added was 80 parts per 100 parts of the calcined gypsum.

The same applies to the following comparative examples. The results are shown in Table 1, and it can be seen that the sample has characteristics in various aspects compared to the comparative example.

Comparative Example 1 A sample was prepared by casting and drying a slurry consisting of only 800 parts of calcined gypsum and 640 parts of deionized water without using a water repellent, and the same test as in Example 1 was conducted.

Comparative Example 2 A sample was prepared in the same manner as in Example 1, except that in Example 1, only 160 parts of emulsion polymer A was added to a mixed slurry consisting of 800 parts of calcined gypsum and 560 parts of deionized water, without using paraffin emulsion a. was manufactured and tested.

Comparative Example 3 A sample was manufactured and tested in the same manner as in Comparative Example 2, except that emulsion polymer A was replaced with emulsion polymer B.

Comparative Examples 4 to 8 In Example 1, emulsion polymer A was not used, and paraffin emulsion a was used in the amount shown in Table 1, or paraffin emulsion a was replaced with the water repellent agent as shown in Table 1. Samples were prepared and tested as in Example 1, except that the amounts indicated were used and the amount of deionized water added was adjusted.

Comparative Example 9 Example 1 except that paraffin emulsion a was replaced with water repellent agent A and the amount of deionized water added was adjusted.
Samples were manufactured and tested in the same manner.

However, when the gypsum slurry was cast and solidified, organic components oozed out and a uniform sample could not be obtained.

From the results shown in Table 1, it can be seen that the water resistance is poor and the mutual effect of the water repellent and the emulsion polymer becomes apparent only when a paraffin water repellent is used.

Comparative Example 10 Samples were manufactured and tested in the same manner as in Example 4, except that the amounts of paraffin emulsion a and emulsion polymer A were reduced as shown in Table 1.

Comparative Example 11 In Reference Example 2-i), sorbitan monostearate and polyethylene glycol monolaurate were treated with dodecylbenzenesulfonic acid I, an anionic surfactant.
A water repellent auxiliary agent was prepared in the same manner as in Reference Example 2-1) except that -IJum was used, and this was designated as Emulsion Polymer C.

An attempt was made to produce a sample in the same manner as in Example 1, except that emulsion polymer A was replaced with emulsion polymer ○.

However, when paraffin emulsion a and emulsion polymer C were added to a mixed slurry of calcined gypsum and deionized water, the emulsion broke and it was not even possible to obtain a fluid slurry.

After solidification of this mixture, a scanning electron micrograph of the fractured surface was taken and is shown in FIG.

(Magnification: 3000x) Conventionally, when producing paraffin emulsions and emulsion polymers, anionic surfactants and nonionic surfactants are usually used together. It has been found that replacing the nonionic surfactant with an anionic surfactant is undesirable because the growth of acicular crystals of gypsum dihydrate is inhibited and water resistance and properties, especially strength, are reduced.

The evaluation results of the above examples and comparative examples are summarized in Table 1.

Figure 1 shows the water resistance and the amount of solid content added; the horizontal axis shows the amount of solid content added in terms of weight relative to calcined gypsum, and the vertical axis shows the results of the one-hour water resistance test. Absorption amount (weight) was taken.

From this diagram, the remarkable complementary effect of the water-repellent composition of the present invention can be clearly understood, and when the wet strength and adhesion to base paper are also taken into consideration, the present invention is industrially very advantageous. I understand what happened.

[Brief explanation of drawings]

FIG. 1 is a chart showing the water resistance of a board using the water-repellent composition of the present invention and a board using a conventional water-repellent agent and water-repellent aid. FIG. 2 is a scanning electron micrograph of the fractured surface of the sample of Example 1. FIG. 3 is a scanning electron micrograph of the fractured surface of the sample of Comparative Example 11.

Claims (1)

[Scope of Claims] 1(a) An emulsion obtained by emulsifying a paraffinic hydrocarbon with a melting point of 40°C to 80°C with a nonionic surfactant, and (b)
) an emulsion polymer emulsified with a nonionic surfactant and having a minimum film forming temperature of 80°C or less, (a
) Solid objects in the component (b) The weight ratio of the solid objects in the component is 2.
A water-repellent composition containing the water-repellent composition in a ratio of 8 to 8 to 2. 2 (a) an emulsion made by emulsifying a paraffinic hydrocarbon with a melting point of 40°C to 80°C with a nonionic surfactant; and (b)
An emulsion polymer emulsified with a nonionic surfactant and having a minimum film formation temperature of 80°C or less, and (c) gypsum, are combined into a solid mass in component (a) and a solid mass in component (b). A water-repellent composition containing the water-repellent composition in a ratio of 2:8 to 8:2.