JPS6011964B2 - Manufacturing method of sealing material - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for manufacturing various sealing materials such as sealing materials for humid pipes and segments, and sealing materials for water leakage and intrusion in general architecture and civil engineering. The present invention relates to a method for producing a sealing material made of an acrylic water-swellable composition that swells in water, has a small amount dissolved in water, and has excellent strength after swelling.

Conventionally, starch, cellulose derivatives, hydrophilic synthetic resins, etc. have been known as water-absorbing polymeric materials, but highly swellable materials with extremely high water absorption, such as starch, have extremely low strength after water absorption. Also, among hydrophilic synthetic resins, those that tend to maintain their strength after absorbing water tend to have inferior water absorbing ability compared to starch, etc., while resins with high water absorbency tend to retain their strength after absorbing water. Each has advantages and disadvantages, such as greater volume loss due to dissolution. Therefore, it is generally difficult to apply such polymeric materials to the above-mentioned sealing materials.For this reason, conventionally, it is possible to swell with a high absorption rate while reducing the amount dissolved when water is absorbed or hydrated. There has been a strong desire for an excellent sealing material that can maintain sufficient strength.

As a result of intensive studies from the above point of view, the inventors have discovered a material that is known to have excellent durability such as heat resistance, weather resistance, and chemical resistance, which are generally required for sealing materials.
Using a meth)acrylic acid alkyl ester polymer, this polymer is further graft-polymerized with a specific ethylenically unsaturated monomer, and then converted into a salt, which has a high water absorption property, dissolved content during water absorption, and after water absorption. They found that it gave very good results in terms of strength and strength, making it suitable for use as a sealing material, and this led to the completion of this invention.

That is, the present invention provides a (meth)acrylic acid alkyl ester polymer (meth) having a water absorption rate of 2% by weight or less in water.
(hereinafter simply referred to as acrylic polymer), the water absorption rate of the homopolymer or copolymer salt in water is 1.
By polymerizing one or more ethylenically unsaturated monomers containing at least one carboxyl group-containing unsaturated monomer that can be 0% by weight or more, and then treating with a basic compound consisting of an alkali metal compound. , to obtain a sealing material made of an acrylic water-swellable composition containing, as one of the polymer components, a salt of an acrylic graft polymer obtained by graft polymerization of the ethylenically unsaturated monomer to the acrylic polymer. The present invention relates to a manufacturing method of a characteristic sealing material.

As described above, in this invention, when one or more specific ethylenically unsaturated monomers are polymerized in the presence of an acrylic polymer and further treated with a specific basic compound after this polymerization, , in addition to salts of homopolymers or copolymers of the acrylic polymer and the ethylenically unsaturated monomer, salts of acrylic graft polymers obtained by graft polymerization of the ethylenically unsaturated monomer to the acrylic polymer; is generated.

In particular, the salt of the above acrylic graft polymer not only reduces the amount dissolved during water absorption, resulting in high water absorption, but also gives good results in terms of strength after water absorption and swelling. It was developed because it was found that it has good water retention properties that do not easily release water even when exposed to water or under a slight pressure, and that these properties make it a suitable material as a sealing material.

At present, it is not necessarily clear what the reason for this effect is.

However, the salt of the homopolymer or copolymer of the specific ethylenically unsaturated monomer used in the present invention, which is obtained by polymerizing the specific ethylenically unsaturated monomer in the absence of an acrylic polymer, alone cannot improve water absorption. Even if this is possible, satisfactory results cannot be obtained in terms of dissolved content during water absorption, strength after water absorption, and water retention. In addition, when the above homopolymer or copolymer salt is blended with an acrylic polymer, problems may arise in the compatibility between the two, and even if they are mixed, the water absorption, the amount dissolved during water absorption, and the strength after water absorption may be affected. It is not possible to satisfy both water retention and water retention properties at the same time.

Furthermore, even when the specific ethylenically unsaturated monomer is added to the polymerization system during synthesis of an acrylic polymer and polymerized, it is difficult to simultaneously improve each property as described above. From these facts, the presence of the salt of the acrylic graft polymer, that is, the coexistence of this salt with the acrylic polymer and the salt of the homopolymer or copolymer, improves water absorption, the dissolved content during water absorption, and the strength after water absorption. It is clear that it plays a major role in improving both water retention and water retention, making it suitable as a sealing material.

The acrylic polymer used in this invention has a water absorption rate of 2% by weight or less in water, and such acrylic polymers are conventionally known, and generally contain an alkyl ester of acrylic acid or methacrylic acid. The main monomer is usually used in combination with another vinyl monomer that can be copolymerized with the above main monomer, and these are mixed in an appropriate ratio using a chain transfer agent such as mercaptan if necessary to achieve a predetermined molecular weight. It can be obtained by polymerization as follows. The polymerization means is arbitrary, and conventionally known methods such as solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization can be employed. Specific examples of copolymerizable vinyl monomers that can be used in combination with the main monomer include styrene, acrylonitrile, vinyl acetate, vinyl chloride, vinyl propionate, maleic acid mono- or ester, acrylic acid, methacrylic acid, crotonic acid, maleic acid. Acid, itaconic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, N.
N-dimethylaminoethyl acrylate, N・N-dimethylaminoethyl methacrylate, N-tert-butylaminoethyl acrylate, bis(N・N-dimethylaminoethyl) maleate, acrylamide, methacrylamide, N-methylolacrylamide, glycidyl acrylate, etc. There is.

The proportion of these copolymerizable monomers varies depending on the performance required of the acrylic polymer as a sealing material, but if the homopolymer or copolymer has a high water absorption rate in water, it may be copolymerized with the main monomer. The water absorption rate of the acrylic polymer obtained should be 2% or less. If the water absorption rate is higher than the above, problems will arise in terms of the amount dissolved during water absorption, strength, and water retention when used as an acrylic graft polymer, which is unsuitable. In this invention, the ethylenically unsaturated monomer to be post-polymerized in the presence of the above-mentioned acrylic polymer is one whose water absorption rate in water when made into a homopolymer or copolymer salt is 100% by weight or more. is used selectively.

If the water absorption rate is lower than the above, the water absorption rate or amount of water absorption after forming the salt of the acrylic graft polymer will be low, making it impossible to obtain sufficiently satisfactory water absorption. In addition,
In this specification, water absorption rate means that when a polymer or its salt is immersed in water until its water absorption becomes constant, the initial weight (before dipping) is W, and the weight after immersion (water absorption) is W. When the weight is W2, water absorption rate = (W2 - W,)/W, x 100
It is expressed in (%).

As such an ethylenically unsaturated monomer, an unsaturated monomer containing a carboxyl group as at least one component thereof is used.

Specific examples include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, aconitic acid, monoalkylmaleic acid, monoalkylfumaric acid, and monoalkylitaconic acid.
In addition, as other ethylenically unsaturated monomers, hydroxyl group-containing (meth)acrylates, N-alkyl (meth)acrylates, N-acyl (meth)acrylates, vinylpyrrolidones, vinylpyridines, (meth)acrylates, ) Acrylic acid amides and the like can also be used in combination with the above-mentioned carboxyl group-containing unsaturated monomer.

Specific examples of hydroxyl group-containing (meth)acrylates include 3-hydroxyethyl acrylate, 8-hydroxypropyl acrylate, y-hydroxypropyl acrylate, 8-hydroxyallyl acrylate,
Examples include acrylates such as glycerol monoacrylate, ethylene glycol monoacrylate, propylene glycol monoacrylate, diethylene glycol monoacrylate, and polyethylene glycol monoacrylate, and methacrylates of the same type as above.

As N-alkyl (meth)acrylates, N・N
-dimethylaminoethyl acrylate, N・N-diethylaminoethyl acrylate, N-methylaminoethyl acrylate, N-ethylaminoethyl acrylate,
N-tert-butylaminoethyl acrylate, N.
N-dimethylaminof.

Examples include acrylates such as lopylacrylate and N·N-dimethylaminoptylacrylate, and methacrylates similar to those mentioned above. N-acyl (meth)acrylates include 2-( represented by the following general formula: (wherein, R is hydrogen or a methyl group, and R. and R2 are hydrogen or an alkyl group having 1 to 4 carbon atoms). N-
acyl)aminoethyl (meth)acrylates are typical, and other 2-(N-acyl)aminoalkyl (meth)acrylates can also be used.

Examples of vinylpyrrolidones include 1-vinyl-2-pyrrolidone, 1-vinyl-5-methyl-2-pyrrolidone, 1-vinyl-5-methyl-2-pyrrolidone,
Examples include vinyl-4-methyl-2-pyrrolidone,
In addition, as pinylpyridines, 2-vinylpyridine,
Examples include 4-vinylpyridine, 2-pinyl-4-methylpyridine, and 4-vinyl-2-(2-hydroxyethyl)pyridine.

Furthermore, examples of (meth)acrylic acid amides include acrylamide and methacrylic acid amide. In this invention, other ethylenically unsaturated monomers that can be used in combination with the carboxyl group-containing unsaturated monomer include, in addition to the hydrophilic unsaturated monomers mentioned above, examples include styrene, vinyl acetate, acrylonitrile, Examples include monomers such as alkyl esters of acrylic acid or methacrylic acid and derivatives thereof.

The proportion of these carboxyl group-free unsaturated monomers should be such that when the copolymer is made into a salt, the water absorption in water can be 10% by weight or more. In this invention, the ratio of the ethylenically unsaturated monomer to the acrylic polymer varies depending on the type of acrylic polymer and ethylenically unsaturated monomer, and also depends on the required amount of water absorption, etc., but it is generally For this purpose, the amount is preferably about 20 to 20 parts by weight, preferably about 30 to 10 parts by weight, based on 10 parts by weight of the acrylic polymer.

Post-polymerization of the ethylenically unsaturated monomer is carried out by adding a predetermined amount of the above monomer to the acrylic polymer, and using an appropriate radical polymerization catalyst, by solution polymerization or bulk polymerization according to a conventional method. It can be done by

In some cases, it is also possible to initiate polymerization using energy such as light or electron beams. As the radical polymerization catalyst, azo compounds such as azobisisobutylonitrile may be used, but particularly preferred are benzyl peroxide, cumene hydro/gu oxide, di-tert-butyl peroxide, te Specific butyl/dioxybenzoate, lauroyl/gu oxide,
Organic peroxides such as ketone peroxide, rt-butylperoxy 2-ethylhexanoate, methyl ethyl ketone peroxide, and cyclohexanone peroxide are preferably used.

The amount of these catalysts used is usually 0.01 to 5 parts by weight, preferably 0.01 to 5 parts by weight, based on 10 parts by weight of the ethylenically unsaturated monomer.
．． It is about 0.05 to 3 parts by weight. Examples of organic solvents for solution polymerization include toluene, benzene, xylene, hexane, heptane, n-octane, isooctane, ethyl acetate, acetone, methyl ethyl ketone, methanol, ethanol, and isopropanol.

The most preferable solvent from the viewpoint of polymerization workability is toluene alone or a mixed solvent containing toluene in an amount of 5% by weight or more. The amount of these organic solvents used is usually 5 to 90 parts by weight, preferably 25 to 40 parts by weight, based on 10 parts by weight of the acrylic polymer. On the other hand, when performing bulk polymerization, there is a risk of gelation during the polymerization operation, and this gelation not only makes the polymerization operation difficult but also has a negative effect on the moldability of the resulting acrylic graft polymer salt. .

Therefore, when bulk polymerization is employed, it is generally desirable to use an appropriate chain transfer agent to control the molecular weight. In particular, when selecting and using an acrylic polymer with a relatively high molecular weight, the use of the chain transfer agent is essential. As such chain transfer agents, conventionally known ones such as thioglycol, thioglycolic acid, butyl mercaptazo, lauryl mercaptan, and dodecyl mercaptan can be widely used.

The amount used is generally 0.01 to 1 part by weight, preferably 0.03 to 1 part by weight, per 100 parts by weight of the ethylenically unsaturated monomer.
The amount may be 0.6 parts by weight. The polymerization reaction product thus obtained contains, as one of the polymer components, an acrylic graft polymer obtained by graft polymerization of an ethylenically unsaturated monomer to an acrylic polymer, and this and an acrylic Contains homopolymers and copolymers that do not participate in graft polymerization of polymers and ethylenically unsaturated monomers.

It is desirable that the gel fraction of such a polymer component is suppressed to 1% by weight or less; if it is higher than this, problems may occur in moldability and other problems when used as a sealing material, so it is not preferable. In the present invention, after the above polymerization, the polymer is further treated with a basic compound to form a salt of the acrylic graft polymer and the homopolymer or copolymer not involved in the graft polymerization in the polymerization reaction product. At this time, if the unreacted acrylic polymer has a carboxyl group in its molecule, this polymer is also converted into a salt together with the above-mentioned polymer. As the basic compound used here, an alkali metal compound such as a hydroxide is used. In some cases, alkylamines such as hexylamine and monoethanolamine, ammonia aqueous solutions, and the like may also be used.
The acrylic water-swellable composition of the present invention is mainly composed of a salt of the polymer component as described above, and is generally used as a sealing material in the form of a solvent-free or organic solvent solution. In this case, various additives can be added depending on the purpose of use, and a crosslinking agent is a typical example. This crosslinking agent is added to the composition and crosslinked before or after subjecting it to the molding process necessary for the sealing material, thereby further improving the durability such as heat resistance and oil resistance of the molded sealing material. . In this invention, since acrylic polymer is used as the base material, relatively good strength and durability can be obtained even after water absorption and swelling, but this strength and durability are further improved by the use of a crosslinking agent. Improved. This type of crosslinking agent includes peroxide type, isocyanate type, melamine type,
A wide range of known vulcanizing agents such as thiuram and general rubber vulcanizing agents can be used. Other ingredients that can be incorporated into the sealing material of the present invention include inorganic fillers such as silica, talc, and calcium carbonate, pigments such as red iron,
Examples include various antioxidants and anti-aging agents such as ultraviolet inhibitors.

As detailed above, according to the present invention, the acrylic water can be swollen with a high absorption rate while reducing the dissolved amount during water absorption or hydration, and can also highly satisfy the strength and water retention properties after water absorption. A sealing material made of a swellable composition can be provided.

Examples of this invention will be described below.

In addition, in the following, parts and % shall mean parts by weight and % by weight, respectively. In addition, the water absorption rates below were measured and calculated using the method described above, but the conditions for immersing the polymer or its salt in water until the amount of water absorption becomes constant are as per the 25q0 Underwater Report 4. It was a waste of time. Furthermore, the dissolved content was calculated by the following method. <Dissolved content> The polymer or its salt soaked in water under the conditions for water absorption measurement is taken out, and the weight when dried at 100 oo for 4 hours is defined as W3, and the dissolved content = (W.-
It was expressed as W3/W, )×100(%).

Example 1 A monomer mixture consisting of 3 parts of methyl methacrylate and 70 parts of ethyl acrylate was made into a 50% solution in toluene, and penzoyl peroxide was woven into the solution with a total amount of 10% of the above monomers. 15 parts were added and charged into a 500 ml three-necked flask.

After charging, the atmosphere was replaced with nitrogen for about 2 hours, and then the temperature was raised to 65q0, and a polymerization reaction was carried out for 10 hours. During this time, heat the inner bath,
Cool, control the contents to the above predetermined temperature, and adjust the average molecular weight (
An acrylic polymer having a Mw) of about 350,000 and a water absorption rate of 7% was obtained. The temperature of this polymer solution was raised to 85°C, and 50 parts of n-butyl acrylate was added per 10 parts of polymer solids.
While adding 60 parts of a monomer mixture consisting of % and 50% acrylic acid in portions equivalent to 2 parts every 2 hours,
When the temperature was raised, 10% of the above monomer mixture was added with penzoyl peroxide. The polymerization reaction was carried out for 6 hours by adding the anchor portion all at once.

Next, a solution containing the obtained acrylic graft polymer was added to the theoretical carboxyl group at an o. An organic solvent solution containing a salt of an acrylic graft polymer was prepared by treating it with an aqueous NaOH solution in an amount equivalent to 100 ml, and a sealing material made of the acrylic water-swelling composition of the present invention was prepared. Example 2 The acrylic resin of the present invention was prepared in exactly the same manner as in Example 1, except that a solution containing the acrylic graft polymer was treated using an aqueous NaOH solution of 0.1 equivalent to the theoretical carboxyl group. A sealing material made of a water-swellable composition was obtained.

Comparative Example 1 An organic solvent solution containing an acrylic graft polymer was prepared in exactly the same manner as in Example 1, except that the treatment with the NaOH aqueous solution was not performed, and this was used as a sealing material made of an acrylic water-swellable composition. .

Comparative Example 2 A monomer mixture consisting of 5 parts of n-butyl acrylate and 5 parts of acrylic acid was made into a 30% solution in a 1:1 mixture system of toluene and methanol, and penzoyl peroxide was added to this. 1.0 parts of the above monomer mixture. In addition, 500 samples were added to a three-necked flask.

After the injection, the atmosphere was replaced with nitrogen for about 2 hours, and then the temperature was raised to 60°C and the polymerization reaction was carried out for 6 hours, so that the average molecular weight (M
An organic solvent solution containing an acrylic acid n-butyl-acrylic acid copolymer having a w) of 200,000 was prepared, and this was used as a sealing material comprising an acrylic water-swelling composition. Note that this comparative example corresponds to one obtained by polymerizing the monomer polymer for post-polymerization of Example 1 in the absence of an acrylic polymer. Comparative Example 3 By treating the organic solvent solution containing the n-butyl acrylate-acrylic acid copolymer obtained by the method of Comparative Example 2 with an aqueous NaOH solution having an amount of 0.01 equivalent to the theoretical carboxyl group, An organic solvent solution containing the salt of the above copolymer was prepared, and this was used as a sealing material made of an acrylic water-swellable composition.

Comparative Example 4 A sealing material made of an acrylic water-swollen composition was obtained in exactly the same manner as in Comparative Example 3, except that the treatment was performed using an aqueous NaOH solution of 0.1 equivalent to the theoretical carboxyl group. .

Comparative Example 5 To a solution containing an acrylic polymer with an average molecular weight (Mw) of about 35 and a water absorption rate of 7% obtained in the same manner as in Example 1, the solution in Comparative Example 2 was added to 100 parts of the solid content. A sealing material made of an acrylic water-swellable composition was obtained by mixing the obtained solution containing the n-butyl acrylic acid-acrylic acid copolymer so that the solid content thereof was 6 parts.

Comparative Example 6 Instead of the solution containing the acrylic acid n-butyl-acrylic acid copolymer obtained in Comparative Example 2, acrylic acid n obtained in Comparative Example 3 was used.
A sealing material made of an acrylic water-swellable composition was obtained in exactly the same manner as in Comparative Example 5, except that a solution containing a salt of a -butyl-acrylic acid copolymer was used.

In this comparative example, the monomer mixture for post-polymerization of Example 1 was separately polymerized without post-polymerization in the presence of the acrylic polymer, and the acrylic polymer of Example 1 was polymerized as a salt. It corresponds to a blend of Comparative Example 7 Instead of the solution containing the n-butyl acrylate-acrylic acid copolymer obtained in Comparative Example 2, the n-acrylic acid obtained in Comparative Example 4 was used.
A sealing material made of an acrylic water-swellable composition was obtained in exactly the same manner as in Comparative Example 5, except that a solution containing a salt of a -butyl-acrylic acid copolymer was used.

Comparative Example 8 3 parts of methyl methacrylate, 70 parts of ethyl acrylate,
3 parts of n-butyl acrylate and 3 parts of acrylic acid were made into a 40% solution in toluene, and 0.0 parts of penzoyl peroxide was added to this solution based on 100 parts of the total amount of the above monomers.
Two samples were added and placed in a 500' three-necked flask.

After the addition, the mixture was purged with nitrogen for about 2 hours, and then the temperature was raised to 0.6% to carry out a polymerization reaction for 7 hours. The average molecular weight (Mw
) is about 250,000 acrylic polymer organic solvent solution,
0.01 equivalent of NaO to its theoretical carboxyl group
An organic solvent solution containing a salt of an acrylic polymer was prepared by treatment with an aqueous H solution, and this was used as a sealing material made of an acrylic water-swellable composition. This comparative example is
This corresponds to the case where the monomer mixture for post-polymerization of Example 1 was added to the polymerization system during the synthesis of the acrylic polymer of Example 1 and copolymerized. The sealing materials of Examples 1 to 2 and Comparative Examples 1 to 8 above were applied to one side of template paper, dried, and then peeled off to prepare a test piece with a size of 25 sides x 25 ribs. The results of examining the percentage and dissolved content are shown in the table below.

For reference, the table clearly states whether each sealing material is one-stage polymerization, two-stage polymerization, or a blended product, and also indicates the basic compound used in the case of polymer salts. The types are also listed. As is clear from the above table, it can be seen that the sealing material of the present invention achieves high water absorption with a reduced dissolved amount.

Claims (1)

[Claims] 1. In the presence of a (meth)acrylic acid alkyl ester polymer having a water absorption of 20% by weight or less, the water absorption of a homopolymer or copolymer salt in water is 100% by weight or more. By polymerizing one or more ethylenically unsaturated monomers, including at least a carboxyl group-containing unsaturated monomer, and then treating with a basic compound consisting of an alkali metal compound, it can be used as one of the polymer components. To obtain a sealing material made of an acrylic water-swellable composition containing a salt of an acrylic graft polymer obtained by graft polymerizing the ethylenically unsaturated monomer to the (meth)acrylic acid alkyl ester polymer. Features: Manufacturing method of sealing material. 2. The method for producing a sealing material according to claim 1, wherein a sealing material is obtained from an acrylic water-swellable composition prepared by blending a crosslinking agent with a polymer component containing a salt of an acrylic graft polymer.