JP2022125894A - Water-swelling water stop composition - Google Patents

Abstract

To provide a water-swelling water stop composition from which a seal material excellent in flexibility, water-stopping property, and stability can be produced.SOLUTION: The present invention provides the water-swelling water stop composition containing (1) a crosslinkable rubber, (2) a water-absorbing resin, (3) a dehydrating agent, (4) a softening agent, and (5) a crosslinking agent and a crosslinking accelerator. The content of the water-absorbing resin is 5-200 pts.mass, the content of the dehydrating agent is 2-20 pts.mass, the content of the softening agent is 10-60 pts.mass, the total content of the crosslinking agent and the crosslinking accelerator is 0.5-15 pts.mass, and the content of the crosslinking accelerator is 0-1.5 pts.mass based on 100 pts.mass of the crosslinkable rubber.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a water-swellable waterproof composition from which sealing materials can be produced.

Patent Literature 1 discloses a sealing material produced using a water-swellable waterproof composition.

JP-A-4-304251

A sealing material produced using a water-swellable water-stopping composition absorbs water and expands in volume when in contact with water, thereby exhibiting water-stopping properties. Such a sealing material is desired to have a certain degree of flexibility in terms of usability, in addition to being excellent in waterproof performance. Further, it is desired that stable waterproofing performance is exhibited even after long-term use.

The present invention has been made in view of such circumstances, and provides a water-swellable water-stopping composition that can produce a sealing material having excellent flexibility, water-stopping properties, and stability.

According to the present invention, a water-swellable rubber containing (1) a cross-linkable rubber, (2) a water-absorbing resin, (3) a dehydrating agent, (4) a softening agent, (5) a cross-linking agent and a cross-linking accelerator. A water stopping composition comprising 5 to 200 parts by mass of the water-absorbing resin, 2 to 20 parts by mass of the dehydrating agent, and 10 to 60 parts by mass of the softening agent per 100 parts by mass of the crosslinkable rubber, A water-swellable waterproof composition is provided in which the total amount of the cross-linking agent and the cross-linking accelerator is 0.5-15 parts by mass, and the cross-linking accelerator is 0-1.5 parts by mass.

As a result of extensive studies, the inventors of the present invention have found that the composition having the above composition can solve the above problems, and have completed the present invention.

The schematic diagram of the steel water stoppage tester used for water stoppage performance evaluation is shown.

1. Composition of water-swellable water-stopping composition The water-swelling water-stopping composition according to the present invention comprises (1) a crosslinkable rubber, (2) a water-absorbing resin, (3) a dehydrating agent, (4) a softening agent, ( 5) It contains a cross-linking agent and a cross-linking accelerator.

(1) Cross-linkable rubber The cross-linkable rubber is not particularly limited as long as it can be cross-linked with a cross-linking agent and the strength is improved. rubber (CR), nitrile-butadiene rubber (NBR), acrylic rubber, ethylene-propylene-diene rubber (EPDM), butyl rubber and the like. Among these, chloroprene rubber is preferable from the viewpoint of water resistance.

(2) Water-absorbing resin Water-absorbing resins include, for example, a partially neutralized crosslinked product of polyacrylic acid, a hydrolyzate of starch-acrylonitrile graft polymer, a neutralized product of starch-acrylic acid graft polymer, vinyl acetate- saponified acrylic acid ester copolymer, carboxymethylcellulose crosslinked product, hydrolyzate of acrylonitrile copolymer or acrylamide copolymer or crosslinked product thereof, crosslinked product of cationic monomer, crosslinked isobutylene-maleic acid copolymer, A crosslinked product of 2-acrylamide-2-methylpropanesulfonic acid and acrylic acid, a sodium salt of carboxymethylcellulose, an ammonium salt of carboxymethylcellulose, and the like are known. Among these, the partially neutralized polyacrylic acid crosslinked product is preferable because the water swelling property is not easily lowered even when the water swelling and shrinkage due to drying are repeated.

The amount of the water-absorbing resin used is 5 to 200 parts by mass, preferably 15 to 145 parts by mass, more preferably 25 to 90 parts by mass, based on 100 parts by mass of the crosslinkable rubber. If the amount of the water-absorbing resin is too small, the water-swelling property may be insufficient and the water-stopping property may be deteriorated. The amount of the water-absorbent resin used relative to 100 parts by mass of the crosslinkable rubber is, for example, 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130. , 140, 145, 150, 160, 170, 180, 190, 200 parts by weight, and may be within a range between any two of the numerical values exemplified here.

(3) Dehydrating agent By heating in the cross-linking process in which the cross-linkable rubber is cross-linked, the water contained in the material becomes water vapor, and the water vapor generates air bubbles in the cross-linked rubber. A dehydrating agent is used for this purpose. Examples of dehydrating agents include, but are not limited to, calcium oxide, silica gel, molecular sieves, activated alumina, barium oxide, strontium oxide, and the like. Among these, calcium oxide is preferred because of its good dehydration properties.

The dehydrating agent is used in an amount of 2 to 20 parts by mass, preferably 3.5 to 13 parts by mass, more preferably 4 to 9 parts by mass, per 100 parts by mass of the crosslinkable rubber. If the amount of the dehydrating agent is too small, the suppression of the generation of air bubbles may be insufficient, and if the amount of the dehydrating agent is too large, the water swellability may deteriorate. The amount of the water-absorbing resin used relative to 100 parts by mass of the crosslinkable rubber is, for example, 2, 3, 3.5, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. , 16, 17, 18, 19, 20 parts by weight, and may be within a range between any two of the numerical values exemplified herein.

(4) Softeners Softeners include paraffinic or naphthenic process oils, vegetable oils, paraffins such as liquid paraffin, waxes, phthalic acid, adipic acid, sebacic acid or phosphoric acid ester plasticizers, Liquid rubbers such as stearic acid or its esters, polybutadiene, polyisoprene and polybutene can be used.

Examples of vegetable oils include linseed oil, perilla oil, olive oil, grape sheet, corn oil, sesame oil, rice bran oil, soybean oil, rapeseed oil, palm oil, sunflower oil, safflower oil, cottonseed oil, and peanut oil.

When the crosslinkable rubber is chloroprene rubber, the softening agent is preferably rapeseed oil from the viewpoint of the amount of elution into water.

The content of the softener is 10 to 60 parts by weight, preferably 21 to 52 parts by weight, more preferably 30 to 46 parts by weight, based on 100 parts by weight of the crosslinkable rubber. Too little softening agent may result in insufficient flexibility, and too much softening agent may result in increased elution into water. The amount of the softener used is, for example, 10, 15, 20, 21, 25, 30, 35, 40, 45, 46, 50, 52, 55, 60 parts by weight with respect to 100 parts by weight of the crosslinkable rubber, It may be in a range between any two of the numerical values exemplified here.

(5) Cross-linking Agent and Cross-linking Accelerator The cross-linking agent and cross-linking accelerator are used for the purpose of cross-linking the cross-linkable rubber and promoting the cross-linking.

Examples of cross-linking agents include, but are not limited to, sulfur compounds such as sulfur and polysulfides, metal oxides such as zinc oxide and magnesium oxide, p-quinonedioxime, and p,p'-dibenzoylquinone. Examples include oxime compounds such as oxime, organic peroxide compounds such as t-butyl hydroperoxide, acetylacetone peroxide and cumene hydroperoxide. Among these, sulfur-based compounds are preferred, and the sulfur-based compounds may be used in combination with other compounds.

The following crosslinkers are particularly preferred for the following rubbers:

・Chloroprene rubber: sulfur compounds, metal oxides, oxime compounds, organic peroxide compounds ・Ethylene, propylene, diene rubber: sulfur compounds, oxime compounds, organic peroxide compounds ・Butyl rubber: sulfur compounds, oxime compounds

Examples of cross-linking accelerators include thiuram-based compounds such as tetramethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, and dipentamethylenethiuram tetrasulfide, and thiazole-based compounds such as 2-mercaptobenzothiazole and dibenzothiazole disulfide. , carbamate compounds such as zinc dimethyldithiocarbamate and zinc dibutyldithiocarbamate, aldehydeamine compounds such as n-butyraldehyde aniline, sulfenamide compounds such as N-cyclohexyl-2-benzothiazylsulfenamide, Examples include guanidine compounds such as diorthotriylguanidine and diorthonitrileguanidine, thiourea compounds such as ethylenethiourea, thiocarbanilide, diethylthiourea and trimethylthiourea, and compounds such as zinc oxide. The cross-linking accelerator may be used alone or in combination of two or more.

For the following rubbers, the following cross-linking accelerators are particularly preferred. In chloroprene rubber, metal oxides act as cross-linking agents, so it is preferable to use a cross-linking accelerator other than metal oxides.

・Chloroprene rubber: thiuram compounds, thiazole compounds, guanidine compounds, thiourea compounds ・Ethylene/propylene/diene rubber: thiuram compounds, thiazole compounds, carbamate compounds, aldehydeamine compounds, sulfenamide compounds , zinc oxide/butyl rubber: thiazole compounds, carbamate compounds, zinc oxide

The total amount of the cross-linking agent and cross-linking accelerator used is preferably 0.5-15 parts by mass, more preferably 7.5-10.2 parts by mass, and 8.7-9. 9 parts by weight is most preferred. If the total amount of the cross-linking agent and the cross-linking accelerator used is too small, the shape retention property when swollen with water may be poor, and the water stoppage, extraction rate and repeatability may also be poor. Also, if the total amount of the cross-linking agent and the cross-linking accelerator used is too large, the water swellability may be insufficient. The total amount of the cross-linking agent and the cross-linking accelerator used with respect to 100 parts by mass of the cross-linkable rubber is, for example, 0.5, 1.0, 3.0, 5.0, 7.5, 8.0, 8.0. 7, 9.9, 10.2, 14.0 and 15.0 parts by mass, and may be within a range between any two of the numerical values exemplified here.

The amount of the cross-linking agent used is, for example, 0.5 to 15.0 parts by mass with respect to 100 parts by mass of the crosslinkable rubber, specifically 0.5, 1.0, 3.0, 5.0, 7.0, 9.0, 11.0, 13.0, 14.0, 15.0 parts by mass, and may be within a range between any two of the numerical values exemplified here. The amount of the cross-linking accelerator used is, for example, 0 to 1.5 parts by mass with respect to 100 parts by mass of the crosslinkable rubber. 2, 1.5 parts by mass, and may be within a range between any two of the numerical values exemplified here.

(6) Additives In the water-swellable waterproof composition of the present invention, if necessary, inorganic fillers, antioxidants, UV inhibitors, tackifying resins, lubricants, and dispersants that are used in ordinary rubber Various additives such as agents and cross-linking accelerators can also be used in combination.

The inorganic filler is used in an amount of, for example, 1 to 50 parts by mass with respect to 100 parts by mass of the crosslinkable rubber. 50 parts by mass, and may be within a range between any two of the numerical values exemplified here. Silica is preferred as the inorganic filler.

2. Production method and use of water-swellable water-stopping composition The water-swelling water-stopping composition of the present invention can be produced by blending the necessary components and then kneading the blend. Moreover, a molded article can be produced by molding the obtained composition into a desired shape and then crosslinking the composition by heating at a temperature equal to or higher than the crosslinking initiation temperature. This molded body can be used as a sealing material.

Apparatuses for kneading the compound include known kneading apparatuses such as mixers, Banbury mixers, kneader mixers, and two-rollers. As an apparatus for molding the kneaded compound, there are conventionally known molding apparatuses such as press molding, extrusion molding, and calender molding. In general, crosslinking can be accomplished by extruding the compound into the product form in a rubber extruder and then heating in a press. Further, the shape of the molded body may be designed appropriately according to the application, such as sheet-like or tape-like.

The sealing material produced using the water-swellable water-stopping composition of the present invention is resistant to elution of the water-absorbing resin even after long-term use, and the sealing material is less likely to lose its wall thickness, thereby reducing the water-stopping effect. Since it is suppressed, it is extremely useful in the fields of civil engineering and construction using pipes and concrete products used in water-conducting parts. In addition, the sealing material produced using the water-swellable water-blocking composition of the present invention can be sufficiently It can exhibit a good water stopping effect.

EXAMPLES The present invention will be described in more detail below with reference to examples. In addition, below, the unit of the usage amount of each substance is parts by mass or % by mass.

1. Preparation of water-swellable waterproof composition A mixture of the components shown in Tables 1 to 4 at the ratios shown in Tables 1 to 4 was mixed at 100 ° C. using a 3 L pressure kneader (manufactured by Moriyama, model: DS3-10MWB-S). By kneading for 10 minutes, water-swellable waterproof compositions of Examples and Comparative Examples were obtained.

Details of each component in the table are as follows.
<Crosslinkable rubber>
・Chloroprene rubber (manufactured by Denka Co., Ltd., “ES-70”)
・Ethylene-propylene-diene rubber (manufactured by Sumitomo Chemical Co., Ltd., "Esprene 505")
・Butyl rubber: "Butyl 268" manufactured by JSR Corporation
<Water absorbent resin>
・ Polyacrylic acid partially neutralized crosslinked product: “Aqualic CS-6S” manufactured by Nippon Shokubai Co., Ltd.
・Carboxymethylcellulose sodium salt: manufactured by Hayashi Pure Chemical Industries, Ltd. ・Carboxymethylcellulose ammonium salt: manufactured by Nichirin Chemical Industry Co., Ltd., “Kikkolate NA-H”
<Dehydrating agent>
・ Calcium oxide: “VESTA-18” manufactured by Inoue Lime Industry Co., Ltd.
<Softener>
・ Rapeseed oil-based softener: “J Rapeseed White Oil” manufactured by J-Oil Mills Co., Ltd.
・ Naphthenic process oil: “NP-24” manufactured by Idemitsu Kosan Co., Ltd.
<Crosslinking agent>
・Sulfur powder (manufactured by Hosoi Chemical Industry Co., Ltd.)
・Zinc oxide (manufactured by Sakai Chemical Co., Ltd., "Zinchua No. 3")
・ Magnesium oxide ("Kyowamag 150" manufactured by Kyowa Chemical Industry Co., Ltd.)
<Crosslinking accelerator>
・Zinc oxide (manufactured by Sakai Chemical Co., Ltd., "Zinchua No. 3")
・Ethylene thiourea (manufactured by Sanshin Chemical Industry Co., Ltd., "Suncellar 22C")
<Inorganic filler>
・ Silica: “Nipsil VN3” manufactured by Tosoh Silica Co., Ltd.

2. Manufacture of Molded Body for Evaluation Each component of the compositions of Examples and Comparative Examples was uniformly kneaded with a roll machine (temperature: 40° C., time: 10 minutes), and processed into a sheet. Next, the obtained sheet material was crosslinked at 170° C. for 16 minutes to obtain a 2 mm-thick molded product for evaluation.

3. Evaluation Various evaluations shown below were performed using the molding for evaluation. Among the following evaluations, "flexibility" is an index of the flexibility of the molded body, and "water swelling", "water stoppage", "shape retention after water swelling", and "non-bubble" are , is an index of the water stoppage of the molded article, and "dissolution into water" and "water swelling repeatability" are indexes of the stability of the molded article.

Evaluation results are shown in Tables 1 to 4. As shown in the table, the molded articles produced using the compositions of the examples gave good results in all evaluation items, indicating that they are excellent in flexibility, waterproofness, and stability. Do you get it. On the other hand, it was found that the molded articles produced using the compositions of Comparative Examples did not have good results in at least one evaluation item, and were not good in at least one of flexibility, water stoppage, and stability.

The details of the evaluation are as follows.

[Flexibility]
According to JIS K-6253, the hardness of the molded product (durometer: type A) was measured and evaluated according to the following criteria.
◎: 50 or more and less than 61 ○: 45 or more and less than 50, or 61 or more and less than 66 ×: less than 45, or 66 or more

[Water swelling]
According to JIS K-6258, a 20 mm × 20 mm × 2 mmt compact was immersed in tap water at 23°C for 7 days, the volume change rate was calculated by the following formula, and the water swellability was evaluated according to the following criteria.
Volume change rate (%) = ((cd) - (ab)) / (ab) x 100
a: weight in air before immersion in water, b: weight in water before immersion in water c: weight in air after immersion in water, d: weight in water after immersion in water ×: less than 10% ○: 10% or more and less than 100% ◎: 100 %that's all

[Dissolution into water]
After immersing a 20 mm × 20 mm × 2 mmt molded body in tap water at 23 ° C. for 7 days, it was dried in an oven at 100 ° C. until the weight of the sample did not change, and the mass was measured and calculated by the following formula. rice field.
Elution rate (%) = (1-mass of molded article after drying/mass of molded article before water immersion) x 100
◎: less than 5% ○: 5% or more and less than 7% ×: 7% or more

[Water stopping]
A molded product with a thickness of 2 mm is placed in a steel water stoppage test machine with an outer diameter of 50 cm shown in FIG. It was soaked for 7 days. After immersion, pressure was applied at intervals of 0.2 MPa and held for 3 minutes, and the presence or absence of water leakage was visually observed to measure the water leakage stop pressure.
◎: Water leakage at 1.2 MPa or more ○: Water leakage at 0.6 MPa or more and less than 1.2 MPa ×: Water leakage at less than 0.6 MPa

[Shape Retention after Water Swelling]
After a molded body of 20 mm×20 mm×2 mmt was immersed in tap water at 23° C. for 7 days, the shape retention of the molded body was visually observed and evaluated according to the following criteria.
◎: No cracks ○: Cracks occur but do not collapse even when taken out of water ×: Disassembled into pieces in water

[Water swelling repeatability]
A compact of 20 mm×20 mm×2 mmt is immersed in tap water at 23° C. for 7 days, and after measuring the water swellability, it is dried in an oven at 80° C. for 1 day and immersed in water again. This operation was repeated three times, and the retention was calculated from the water swellability measured at the first time.
◎: 45% or more ○: 30% or more and less than 45% ×: less than 30%

[No-foaming]
The number of air bubbles of 1 mmφ or more generated on the surface of the 20 mm × 20 mm × 2 mmt compact was visually observed.
◎: Less than 1 ○: 1 or more and less than 3 ×: 3 or more

1 molded body 2 water stop pressure tester 3 bolt 4 water inlet 5 outlet 6 water pressure gauge 7 spacer used at 10% compression

Claims (5)

A water-swellable waterproof composition comprising (1) a crosslinkable rubber, (2) a water-absorbing resin, (3) a dehydrating agent, (4) a softening agent, (5) a cross-linking agent and a cross-linking accelerator. hand,
With respect to 100 parts by mass of the crosslinkable rubber, 5 to 200 parts by mass of the water-absorbing resin, 2 to 20 parts by mass of the dehydrating agent, 10 to 60 parts by mass of the softening agent, and the combination of the cross-linking agent and the cross-linking accelerator A water-swellable waterproof composition containing 0.5 to 15 parts by mass in total and 0 to 1.5 parts by mass of a cross-linking accelerator. 2. The water-swellable waterproof composition according to claim 1, wherein the water-absorbent resin is a partially neutralized crosslinked product of polyacrylic acid. The water-swellable waterproof composition according to claim 1 or 2, wherein the crosslinkable rubber is chloroprene rubber. The water-swellable waterproof composition according to any one of claims 1 to 3, wherein the softener is rapeseed oil. The water-swellable waterproof composition according to any one of claims 1 to 4, which is used as a sealing material.

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