JPH0350209A - Acid-absorbing and swelling resin - Google Patents

Abstract

PURPOSE:To obtain an acid-absorbing and swelling resin which can be stably used in an acid solution for a long time by using a resin having a structure formed by combining two specified vinyl monomers. CONSTITUTION:This acid-absorbing and swelling resin is composed of 30-95wt.% units of at least one vinyl monomer of formula l [wherein R1 is a hydrogen atom or a methyl; and X is COOR2 (wherein R2 is a hydrogen atom or a 1-4C alkyl), formula II or CN] and 5-70wt.% units of at least one vinyl monomer of formula III [wherein R3 is a hydrogen atom or a methyl; R4 and R5 which may be the same or different are each a 1-4C alkyl; Y is O-CnH2n or NH-CnH2n (wherein (n) is an integer of 2-5)]. It cain be obtained by polymerizing the above monomers by using a radical generator such as a peroxide as a polymerization initiator according to a general polymerization process.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to acid-absorbing swelling resins, and relates to resin materials used for improving lead-acid batteries, sealing materials for acid solutions, acid absorbing materials, etc. It is.

<Prior Art> Acid-absorbing swellable resins as resin materials that are easy to manufacture and have excellent processability are desired for use in lead-acid batteries and sealing materials for acid solutions. Particularly in lead-acid batteries, the volume of the plate active material changes during charging and discharging, and this repeated volume change may cause the plate active material to fall off or the contact between the active material and the lattice to deteriorate, resulting in poor battery performance. gradually decreases. In order to improve this problem, for example, in sealed lead-acid batteries, a method is used in which a mat made of fine glass fibers is charged as a sulfuric acid support under pressure.

However, even with these measures, the glass fiber mat shrinks during long-term use, so improvements are desired.

Furthermore, a method of combining glass fiber and a super absorbent resin (Japanese Unexamined Patent Publication No. 60-205963) has been proposed, but this method has drawbacks such as the stability of the super absorbent resin against sulfuric acid.

Furthermore, a method using a copolymer of ethylene and an ethylenically unsaturated comonomer having an amine (JP-A-64-77
No. 882) has also been proposed, but there are constraints on production, such as limitations on polymerization methods and equipment.

<Problems to be Solved by the Invention> The purpose of the present invention is to solve the problems of the conventional methods and to provide an easy-to-manufacture acid-absorbing swelling resin that can be stably used in acid solutions for a long period of time. This is what we provide.

<Means for Solving Problem ii> From this viewpoint, the present inventors have intensively studied a new material that absorbs acid and swells, and is stable in acid, and as a result, has arrived at the present invention.

That is, the present invention provides a monomer unit R8 CHz -C-X (A) represented by the general formula (A) having a vinyl group [wherein R1
is a hydrogen atom or a methyl group, -XhaCOORz (R
z represents a hydrogen atom, carbon or -CN] Monomer units represented by general formula (B) containing 30 to 95% by weight of one or more of the following and a vinyl group [wherein R1 is a hydrogen atom or a methyl group , R4 and R
3 is the same or different and is an alkyl group having 1 to 4 carbon atoms, -
Y- is -0-C, H, -2 to 5 (n is an integer of ←-4=)]
The present invention provides an acid-absorbing swelling resin containing up to 70% by weight as a constituent component.

Monomers with a vinyl group represented by the general formula (A) used in this resin include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, and acrylic. Glycidyl acid, glycidyl methacrylate, vinyl acetate,
Examples include vinyl propionate, styrene, and acrylonitrile. Particularly preferred compounds are methyl acrylate, methyl methacrylate, styrene, and n-butyl acrylate.

Further, as specific examples of the monomer having a vinyl group represented by the -a formula (B), dimethylaminoethyl acrylamide, dimethylaminopropylacrylamide, dimethylaminobutylacrylamide, diethylaminoethyl acrylamide, diethylaminopropylacrylamide, diethylaminobutylacrylamide, dimethylaminobutylacrylamide, Propylaminoethyl acrylamide, dipropylaminopropylacrylamide, dipropylaminobutylacrylamide, N-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide, and their corresponding methacrylamide derivatives, dimethylaminomethylacrylate, dimethyl Aminoethyl acrylate, dimethylaminoisopropylacrylate, dimethylamino normal butyl acrylate, N-methyl-N-ethylaminoethyl acrylate, N-methyl-N-normalbutylaminoethyl acrylate, diethylaminoethyl acrylate, diisopropylaminoethyl acrylate,
These include acrylic acid esters such as di-normal propylamino normal propyl acrylate, di-normal butylaminoethyl acrylate, and di-normal butylamino normal propyl acrylate, and methacrylic acid esters corresponding to these.

Particularly preferred comonomer units include dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, dimethylaminoethylacrylamide,
Examples include dimethylaminoethyl methacrylamide, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl methacrylate, and dimethylaminopropyl acrylate.

The resin of the present invention includes inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, boric acid, and hydrofluoric acid, formic acid, acetic acid, oxalic acid, tartaric acid, benzoic acid, lactic acid, acrylic acid, maleic acid, methanesulfonic acid, It absorbs benzenesulfonic acid and swells. Utilizing this acid-absorbing swelling property, the resin of the present invention can be suitably used as a pressure-applying material for lead-acid batteries, for example.

In commonly used paste type lead-acid batteries,
"Battery Handbook" (Denki Shoin, Translation Part 4 [) 3-
As shown in Figure 3-56 on page 50, it is known that increasing the pressure applied to the positive electrode plate lengthens the life of repeated charging and discharging. Further, it is said that there is a relationship between the pressure P and the durability N as shown in the following equation.

N, -N, (1+KP'') If the swelling ratio of the resin due to acid is less than 10%, sufficient pressure cannot be applied to the electrode plate.

In addition, when a large amount of resin components are eluted into the acid, the melted components of the resin cover the surface of the active material of the electrode plate, causing problems such as inhibiting the reaction between the active material and the acid and increasing electrical resistance. In order to prevent this, it is preferable to suppress the elution of the resin component into the acid to 5% or less.

In order to obtain a resin having the above-mentioned acid part wettability and non-leaching property in acid, the ratio of each monomer unit of general formula (A) and general formula (B) in the resin should be set to the monomer unit of (A). is 30-9
5% by weight, and the monomer unit of CB) is 70 to 5% by weight.

The method for producing the acid-absorbing swellable resin of the present invention is not particularly specified, but includes a monomer having a vinyl group represented by the general formula (A), a monomer having a vinyl group represented by the general formula (B), and polymerization initiation. It can be produced by general polymerization methods such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization using a radical generator such as peroxide as an agent.

The resin of the present invention may be made into a sheet or a non-woven fabric as fibers, or the resin powder or fibers may be mixed with glass fiber, polyethylene fiber, polypropylene fiber, polyester fiber, etc. and heat-fused by heat treatment. By placing it in a mat-like form between the electrode plate group and the battery case, or by using it as a sulfuric acid holder between the electrode plates, it will swell when sulfuric acid is injected, and the electrode plate will Pressure can be applied to the target. This prevents the active material from falling off and maintains good contact between the electrode plate and the sulfuric acid holder, as well as between the active material and the grid, over a long period of time, and improves performance by extending the life of lead-acid batteries. Improvements can be made.

The acid-absorbing swellable resin of the present invention can be used as a lead-acid battery material as described above, but the resin can also be used as it is, or with other resins or various types, by taking advantage of its ability to absorb acid and swell. By mixing it with rubber and molding it, it can be used for applications such as backing and sealing of equipment and equipment that handle acids.

<Examples> Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 12 Monomers (A), monomers (B), and polymerization initiators shown in Table 1 were mixed in predetermined amounts. After pouring this between two glass plates and sealing and fixing the surroundings with gasket,
It was placed in hot water at 0°C and maintained for 8 hours. A sheet-shaped resin was obtained by taking out the resin and removing the packing and glass plate. The results are shown in Table 1.

The various resins obtained above were heat-pressed into sheets with a thickness of 161 mm, and test pieces of 5 CI 11 x 5 cm were cut from each sheet.

Each test piece was immersed in 200 d of sulfuric acid with a specific gravity of 1.3 at 25°C for 4 hours. After taking it out, the length and thickness of each side were measured to determine the volume, and the volumetric swelling rate was measured. The results are also shown in Table 1.

1 (ld) was collected from each sulfuric acid solution in which various resins were immersed, and each was neutralized with a 2N sodium hydroxide solution.

After further diluting with ion-exchanged water to 1000 d, nitrogen and carbon in the aqueous solution was analyzed using a "total organic carbon measuring device" (manufactured by Sumitomo Chemical Co., Ltd.).

The elution amounts of monomer A and monomer B were calculated from the ratio of carbon and nitrogen in the hexamer and the analytical values of carbon and nitrogen in the solution, and the amount of dissolved components relative to the initial amount of sample resin was calculated. The results are also shown in Table 1.

Comparative Examples 1-2 A sheet-shaped resin was obtained in the same manner as in Example 1, except that the monomer (A), monomer (B), and polymerization initiator shown in Table 1 were mixed in the prescribed amounts, and a sulfuric acid immersion test was conducted. Ta. The results are shown in Table 1.

Example 13 The resin (Na 1 ) shown in Table 1 was freeze-pulverized to obtain powder with an average particle size of 150 μm. After stirring 18 g of this powder and 9 g of glass fibers with an average fiber diameter of 0.8 μm with water in a mixer with a capacity of 3 N, mixed papermaking was carried out, and after drying, the mixture was heated at 160°C into a 1.6-thick mold. A paper-made porous mat of 25CIIX251 with a thickness of 1.61 mm was obtained by hot pressing using a 25CIIX251 material.

From this, a sample piece of 2.5 CII x 4 crs was cut out, a load of 200 g/cj was placed on it, and the thickness was measured. Then, after immersing in 100 d of 40% sulfuric acid for 5 minutes,
As a result of measuring the thickness and side length with a load of 00 g/c4 applied, it was confirmed that swelling occurred only in the thickness direction.

Examples 14 to 25 Samples of paper-made porous mats obtained in the same manner as in Example 13 except that the resin powder and fiber shown in Table 2 were used were immersed in sulfuric acid to measure the swelling ratio. The results are summarized in Table 2.

Examples 26 to 28 The produced resin was supplied to a spinning machine equipped with a 20-hole nozzle with a hole diameter of 0.8 at the tip of a 30 mmφ extruder (L/D=15), and the resin fibers were cut into 5 pieces. did. The cut resin fiber samples and other fibers shown in Table 3 were made into paper in the same manner as in Example 13, and heat treated. Then, it was immersed in sulfuric acid to measure the swelling ratio. The results are summarized in Table 3.

Example 29 A test piece with a width of 2.5 cm and a length of 3C'11 was cut out from the sample of mat 2-2 prepared in Example 14.

This test piece was sandwiched between two acrylic resin plates of the same size as the test piece and 31 m thick, and pressed to a pressure of 200 g/aJ while measuring the pressure with a load cell.
Fixed thickness.

Next, sulfuric acid with a specific gravity of 1.3 and 25° C. was injected into the mat test piece using a dropper to allow the mat to absorb the sulfuric acid. The injection amount was 0.9d.

As a result of measuring the pressure applied to the load cell after 10 minutes had passed, it was found to be 830 g/d, indicating that the pressure was applied due to swelling.

Similar measurements were carried out using a glass fiber mat made of glass fibers W having a diameter of 0.8μ, and the pressure was reduced to 130 g/d by injecting sulfuric acid.

<Effects of the Invention> The acid-absorbing swelling resin of the present invention is easy to manufacture, has excellent processability, and can be used stably for a long period of time in an acid solution. Utilizing this property, the resin is suitably used as a separator for lead-acid batteries, a sealing material for acid solutions, or an acid absorbing material.

Claims (3)

[Claims] (1) Monomer unit represented by the general formula (A) having a vinyl group ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (A) [In the formula, R_1 is a hydrogen atom or a methyl group, and X is -CO
30 to 95% by weight of one or more of OR_2 (R_2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), ▲a mathematical formula, chemical formula, table, etc.▼, or -CN], and a vinyl group. A monomer unit represented by the general formula (B) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B) Alkyl group, -Y- is -O-CnH_2_m-, -NH-C_n
H_2_n-, (n is an integer of 2 to 5)] An acid-absorbing swelling resin containing 5 to 70% by weight of one or more of the following as a constituent component. (2) The acid-absorbing swellable resin according to claim 1, wherein the monomer unit represented by the general formula (A) is one or more types selected from methyl methacrylate, methyl acrylate, n-butyl acrylate, and styrene. (3) The monomer unit represented by general formula (B) is selected from dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, dimethylaminoethyl acrylamide, dimethylaminoethylmethacrylamide, dimethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate. The acid-absorbing swelling resin according to claim 1, which is at least one type of acid-absorbing swellable resin.