JPH0542474B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to aqueous adhesives. More specifically, it relates to an aqueous viscosity whose viscosity changes depending on temperature. Conventional technology and its problems: Conventionally, water-soluble polymers such as polyethylene glycol and polyacrylamide exhibit non-Newtonian viscous flow in aqueous solutions, and specifically, the phenomenon that the viscosity decreases as the shear rate of the aqueous solution increases shows. Taking advantage of such properties, attempts have been made to use the water-soluble polymers described above as friction reducing agents by adding them to fire fighting water and the like. On the other hand, recently, various water-based adhesives have been developed to replace petroleum-based lubricating oils, focusing on their high heat removal ability and excellent flame retardancy or non-combustibility. However, since these water-based adhesives are based on water, they cannot fully reproduce the excellent properties of petroleum-based lubricating oils; Currently, various modification aspects such as systems are being investigated. Means for Solving the Problems: In view of the above points, the present inventors conducted intensive studies focusing on the viscous flow of water-soluble polymers in aqueous solutions, and found that certain N-alkyl or N-alkylene substitutions The present invention was achieved by discovering that by using (meth)acrylamide alone or a copolymer or a copolymer with other copolymerizable monomers, the viscosity of an aqueous solution of these polymers can be controlled by temperature. . That is, the present invention is based on the general formula () (However, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom, methyl group, or ethyl group, and R ₃ represents a methyl group, ethyl group, or propyl group.), or the general formula () (R ₁ is a hydrogen atom or a methyl group, A is (-CH ₂
) _-o , and n is 4 to 6 or ( _-CH2 ) _-2O ( _-CH2 )-
₂
represents. ) This is an aqueous adhesive containing a single or copolymer of N-alkyl- or N-alkylene-substituted (meth)acrylamide, or a copolymer with other copolymerizable monomers. Specifically, the above-mentioned "control of viscosity" referred to in the present invention is defined by the following general formula: S = ηD ⁿ (In the above formula, S is shear stress, D is shear rate, η is a constant, and n is viscosity. ) means that the viscosity index n changes. In general, n=1 in Newtonian viscous flow, and as the non-Newtonian property increases, n becomes smaller than 1. In non-Newtonian viscous flow, the higher the shear rate, the lower the viscosity. Specifically, the N-alkyl- or N-alkylene-substituted (meth)acrylamide represented by the general formulas () and () in the present invention includes, for example, N-n-propylacrylamide (the cloud point of the polymer is 32 ), N-n-propylmethacrylamide, N-isopropylacrylamide (polymer cloud point 29°C), N-isopropylmethacrylamide, N-ethylacrylamide, N,N-
Diethylacrylamide, N-ethylethacrylamide, N,N-dimethylacrylamide, N,
Examples include N-dimethylmethacrylamide, N-acryloylpyrrolidine (polymer cloud point 51°C), N-methacryloylpyrrolidine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylmorpholine, N-methacryloylmorpholine, etc. . In addition, monomers that can be copolymerized with the above monomers include hydrophilic monomers, ionic monomers, lipophilic monomers, etc., and one or more of these monomers are applicable. can. Specifically, as a hydrophilic monomer,
For example, acrylamide, methacrylamide, N
- Methylacrylamide, diacetone acrylamide, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, various methoxypolyethylene glycol methacrylates, various methoxypolyethylene glycol acrylates, N-vinyl-2-pyrrolidone, etc. You can also use vinyl acetate,
Glycidyl methacrylate or the like can also be introduced by copolymerization and hydrolyzed to impart hydrophilicity. Examples of the ionic monomer include acrylic acid, methacrylic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid, and 2-acrylamide-2-
Acids such as methyl-propanesulfonic acid and their salts, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropylmethacrylamide, N , N-dimethylaminopropylacrylamide, and salts thereof. It is also possible to introduce various acrylates, methacrylates, acrylamide, methacrylamide, acrylonitrile, etc. by copolymerization and hydrolyze them to impart ionicity. Examples of lipophilic monomers include N-n-butylacrylamide, N-butylmethacrylamide, N-tert.-butylacrylamide, N-
tert.-butyl methacrylamide, N-n-hexyl acrylamide, N-n-hexyl methacrylamide, N-n-octylacrylamide, N-
N-alkyl (meth)acrylamide derivatives such as n-octyl methacrylamide, N-tert.-octylacrylamide, N-n-dodecyl acrylamide, N-n-dodecyl methacrylamide, ethyl acrylate, methyl methacrylate, butyl methacrylate, butyl acrylate , (meth)acrylate derivatives such as lauryl acrylate, 2-ethylhexyl methacrylate, and glycidyl methacrylate, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, olefins such as ethylene, propylene, butene, styrene, α-methylstyrene, etc. be able to. Next, as a specific method for producing an aqueous adhesive by polymerizing the above monomers, (1) polymerizing in an aqueous solution,
(2) Polymerization in a solvent and then distilling off the solvent after polymerization or adding it to a negative solvent that does not dissolve the polymer. , a method of obtaining a polymer by operations such as precipitation of the polymer, (3) a method of obtaining an aqueous polymer solution by emulsion polymerization at a temperature higher than the cloud point of the polymer, (4) a method of obtaining a polymer as an aqueous solution.
Reverse-phase suspension polymerization in which monomers or their aqueous solutions are dispersed in oil, salting-out suspension polymerization in which a large amount of electrolyte is dissolved in an aqueous solution to suppress monomer solubility, and polymerization at high temperatures. (5) A method in which the polymer is obtained in the form of particles or powder by precipitation polymerization, etc., in which the polymer is precipitated, and (5) a method in which the monomer is directly polymerized without being diluted with a solvent to obtain a polymer block. . At this time, the polymerization can be initiated by heating alone, but better results are usually obtained by using a polymerization initiator. The polymerization initiator is not limited as long as it has the ability to initiate radical polymerization, and includes, for example, inorganic peroxides, organic peroxides, combinations of these peroxides and reducing agents, and azo compounds. Specifically, there are ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl peroxide, benzoyl peroxide, cumene hydroxy peroxide, tert-butyl peroxy-2-ethylhexanoate, butyl perbenzoate, etc. Examples of reducing agents used in combination with these include sulfites, hydrogen sulfites, salts with low ionic valences such as iron, copper, and cobalt, organic amines such as aniline, and reducing sugars such as aldose and getose. can. Examples of azo compounds include azobisisobutyronitrile, 2,2'-azobis-2-amidinopropane hydrochloride, 2,2'-azobis-2,
4-dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleic acid, etc. can be used. It is also possible to use two or more of the above polymerization initiators in combination. In this case, the amount of the polymerization initiator to be added is sufficient to be within a commonly employed quantitative range, for example, from 0.01 to 5% by weight, preferably from 0.05 to 2% by weight, based on the monomer. Among the polymers obtained in this way, block-shaped ones or polymers obtained by distilling off the solvent can be pulverized into powder, or melted and molded into granules, flakes, fibers, or films. However, particulate polymers can be provided as they are, and latex polymers can be provided as an aqueous gel or diluted with water to provide an aqueous polymer solution after being returned to a temperature below the clouding point. The aqueous adhesive provided by the above method is used as it is or diluted with water when it is an aqueous solution, and when it is in the form of powder, granules, flakes or film it is dissolved to a predetermined concentration. When using the aqueous adhesive of the present invention for various purposes,
The concentration of the polymer in the aqueous solution varies depending on the application, but in order to exhibit the high heat removal ability and excellent flame retardant and non-combustible properties as an aqueous adhesive, the water content is preferably at least 40% by weight. is 60% by weight or more, more preferably 70% by weight or more. The aqueous adhesive of the present invention generally becomes hydrophobic in an aqueous solution by heating, and in many cases, the aqueous solution becomes cloudy and exhibits a cloud point, and the hydrophilicity and hydrophobicity of the polymer change depending on the temperature. It is thought that there is a synonymous relationship between this and the change in the viscosity of the aqueous solution. Next, regarding specific methods for measuring viscosity and viscosity index, a wide variety of measurement methods are adopted for viscosity itself, but when the viscous flow of an aqueous solution is non-Newtonian, it depends on the shear rate. Since the viscosity changes, the absolute value of the viscosity itself becomes meaningless. Therefore, in such cases, an expression method is used in which the shear rate is also written, or the viscosity index n, etc. is also written. As a specific method for measuring the viscosity index, any method that can measure the viscosity by changing the shear rate may be used, such as a rotational viscometer, capillary viscosity, rheometer, etc. The viscosity when the aqueous viscous agent of the present invention is dissolved in water is:
Although it cannot be generalized because it varies depending on the type of polymer, concentration, and temperature, at a sticky agent concentration of about 5% by weight, it is 1 to 100,000 centipoise, preferably 1 to 100,000 centipoise.
It is in the range of 10000 centipoise. Furthermore, the aqueous viscous agent of the present invention has the following properties in an aqueous solution:
The lower the temperature, the higher the viscosity, and the higher the temperature, the lower the viscosity. The temperature range that can be used is as long as water can exist in a liquid state, specifically from 0 to
Although the temperature range is 100°C, it is possible to further widen the temperature range by using it in combination with ethylene glycol, etc. On the other hand, the viscosity index n of the aqueous solution becomes more difficult to become a non-Newtonian viscosity index (n<1) than a Newtonian viscosity index (n=1) at lower temperatures, and returns to Newtonian as the temperature increases. , this process is thermoreversible. In addition, such changes in the viscosity index also occur depending on the composition of the copolymer; generally, in a copolymer with hydrophilic monomers, as the proportion of these monomers in the copolymer increases, their Aqueous solutions of copolymers tend to exhibit more non-Newtonian viscous flow. On the other hand, aqueous solutions of copolymers with lipophilic monomers tend to exhibit Newtonian viscous flow. However, an aqueous solution of a copolymer with an ionic monomer may unexpectedly exhibit Newtonian viscous flow. On the other hand, the viscosity of the aqueous solution of these polymers itself is determined approximately by the molecular weight of the polymer, and can be adjusted by appropriately selecting polymerization conditions such as adjusting the amount of polymerization initiator or polymerization method such as emulsion polymerization. Therefore, by using the aqueous viscous agent of the present invention, the viscous flow of the aqueous solution can be controlled by changing the temperature, and the concentration, temperature, viscosity, and viscosity index that characterize the viscosity of the aqueous polymer solution can be specified. However, by considering the constituent factors of the aqueous adhesive of the present invention described above, it is possible to provide an aqueous adhesive that satisfies those requirements. Function: Specific uses of the water-based adhesive of the present invention include hydraulic fluids used in the operation of hydraulic equipment, lubricating fluids used in various processes such as rolling, cutting, grinding, press working, and wire drawing of metals, etc. It can be applied to applications for which petroleum-based lubricating oils have traditionally been used. In addition, in using the aqueous adhesive of the present invention in the above-mentioned specific applications, glycols such as ethylene glycol, propylene glycol and their polymers, preservatives,
It may be used in combination with rust/corrosion inhibitors, oiliness improvers, surfactants, antifoaming agents, inorganic salts, etc. The present invention will be further explained below with reference to Examples. Example 1 Preparation of polymer: 3.5 N-n-propylacrylamide in 25 ml of water
After adding 0.5 g of sodium 2-acrylamido-2-phenylpropanesulfonate (hereinafter abbreviated as APPS-Na) and replacing the inside of the reactor with nitrogen, the temperature was raised to 40°C to emulsify the reaction solution. did. Next, 1 ml of a 5% aqueous potassium persulfate solution was added to the reaction solution to initiate polymerization, which was continued for 6 hours. During the polymerization, the polymerization solution proceeded in an emulsified state and could be sufficiently stirred. When the polymerization liquid was cooled, it became transparent and could no longer be stirred. <Measurement of Viscosity> Water was added to the above Nn-propylacrylamide polymer to dilute it to a concentration of 5% by weight. Then, using the 5% by weight aqueous solution,
Using a No. 3 rotor with a B-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd.), the viscosity was measured at the rotational speed and temperature shown in Table 1, and each value was calculated from the viscosity and measured value at each measurement point. The viscosity index n at temperature is shown.

[Table] Example 2 Production of polymer: 45.0 g of distilled water and 5.0 g of N-acryloylpyrrolidine were added to a 100 ml four-necked round-bottomed flask while stirring under nitrogen gas flow. Then ammonium persulfate 0.50g and sodium bisulfite
0.23g was added and polymerized at 15-30°C for 4 hours. Measurement of viscosity: The viscosity of the above polymer aqueous solution was measured using a B-type rotational viscometer using a BL-type adapter at 25°C and the rotational speed shown in Table 2. Table 2 shows the results and the viscosity index calculated from it. n was shown. Comparative Example 1 Production of polymer: N-acryloylpyrrolidine used in Example 2
A polymer was produced in the same manner as in Example 2 except that 5.0 g of acrylamide was used instead of 5.0 g. Measurement of viscosity: Same as Example 2 at 20°C, 40°C and 60°C
The viscosity was measured and the results are shown in Table 3.

[Table] Example 15 A polymer was produced in the same manner as in Example 2 except that N-isopropylacrylamide was used instead of N-acryloylpyrrolidine.
Using the aqueous polymer solution, the viscosity was measured in exactly the same manner as in Example 2 at 25°C while changing the rotation speed of the rotor. At 60 rpm, the viscosity was 3.4 centipoise,
Even at 30 rpm, it was 3.4 centipoise, at 12 rpm it was 3.7 centipoise, and at 6 rpm it was 3.8 centipoise, and the viscosity index was 0.94. Example 16 30% N,N of N,N-diethylacrylamide
- The dimethylformamide solution was transferred to a Dewar bottle, and after the liquid was purged with nitrogen, 1.5% azobisisobutyronitrile was added at 30°C and polymerized adiabatically. The resulting gel was cut into pieces, dried under vacuum at 60°C, and further ground to obtain powder. Using a 10% aqueous polymer solution obtained by dissolving the powder in cold water, the viscosity was measured in exactly the same manner as in Example 2 at 25°C while changing the rotational speed of the rotor. At 60 rpm, the viscosity was 3.8 centipoise, 3.8 centipoise even at 30 rpm,
It was 4.1 centipoise at 12 rpm, 4.2 centipoise at 6 rpm, and the viscosity index was 0.96. Example 17 A polymer was produced in exactly the same manner as in Example 2 except that N-acryloylmorpholine was used instead of N-acryloylpyrrolidine, and the same procedure as in Example 2 was carried out using the aqueous solution of the polymer. When the viscosity was measured at 25°C by changing the rotor rotation speed, it was 3.0 centipoise at 60 rpm,
Even at 30 rpm, it was 3.0 centipoise, at 12 rpm it was 3.2 centipoise, and at 6 rpm it was 3.3 centipoise, and the viscosity index was 0.97.

[Table] Examples 3 to 6 Polymers were produced in the same manner as in Example 2 except for the polymerization conditions shown in Table 2. The viscosity was measured and the results are shown in Table 2. Examples 7 to 14 Polymers were produced in the same manner as in Example 2, except for the polymerization conditions shown in Table 4. The viscosity was measured at 25°C in the same manner as in Example 2, and the results are shown in Table 4. Indicated. In Examples 12 to 14, the polymers were produced by reducing the amount of polymerization initiator to 1/2.

【table】

Claims (1)

[Claims] 1 General formula () (However, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom, methyl group, or ethyl group, and R ₃ represents a methyl group, ethyl group, or propyl group.), or the general formula () (R ₁ is a hydrogen atom or a methyl group, A is (-
_CH2 ) _-o , where n is 4 to 6 or ( _-CH2 ) _-2O (-
CH ₂ ) ₋₂ . ) An aqueous adhesive comprising an N-alkyl- or N-alkylene-substituted (meth)acrylamide, either alone or as a copolymer, or as a copolymer with other copolymerizable monomers.