JPS6345686B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a composition of an amino-based resin initial condensate, and more specifically, when an amino compound and an aldehyde are subjected to a condensation reaction, cationized polyvinyl alcohol is added to the system before, during, or after the condensation reaction. The present invention relates to a method for producing an amino-based resin initial condensation composition, which comprises adding. Initial condensates of amino resins, such as urea resins and melamine resins, are used in a wide range of applications such as adhesives, molding materials, paper processing agents, fiber processing agents, paints, civil engineering and decorative boards, and are inexpensive. It is also known as a material with excellent water resistance. Among these uses, for adhesive uses, there are particularly high demands on adhesive performance after adhesion, as well as stability and workability as an adhesive. That is, a product obtained by simply condensing an amino compound and an aldehyde has poor stability during the reaction, low temporary adhesive strength during bonding work, and extremely poor storage stability. In order to improve these drawbacks, carboxymethyl cellulose or polyvinyl alcohol (hereinafter simply referred to as
However, although carboxymethylcellulose has a thickening effect, the effect of improving temporary adhesive strength is small;
In addition, although the addition of PVA has excellent improvement effects such as improved adhesive strength and water washability, it also has disadvantages such as thickening when left unused and poor fluidity at low temperatures in winter. Sexuality is still not at a satisfactory level. From this point of view, in order to obtain PVA with better performance than in recent years, acrylamide modification, carboxylic acid modification,
Methods have been proposed for producing amino resin adhesives using PVA that has been chemically modified such as acrolein modification or hydrophobic group modification, but these methods have different stability during reaction, storage stability, and low temperature stability. All of them have advantages and disadvantages in terms of fluidity, temporary adhesive strength, water-resistant adhesive strength, water washability, etc., and it cannot be said that they are at a fully satisfactory level in terms of performance balance. Among these chemically modified PVAs, carboxylic acid-modified PVAs such as crotonic acid-modified, maleic anhydride-modified, and itaconic acid-modified PVAs have relatively good effects in terms of washability, stability, and adhesive strength, but on the other hand, they have poor water-resistant adhesion. The disadvantage is that power is lost. The present inventors conducted a more extensive study on chemical modification of PVA, and obtained many modified PVA.
As a result of producing amino-based resins using PVA, it was discovered that cationized PVA provides excellent performance for such uses, and the present invention was completed by establishing an industrially advantageous method for cationic modification of PVA. It is something. The technology of cationically modifying water-soluble polymers such as starch or polyacrylamide has been known and has been produced industrially, but the concept of using PVA modified with cationic groups for the production of amino resins is still unclear. completely unknown. Several methods have been proposed for imparting cationic groups to PVA, but all of them have problems in their modification methods and are difficult to produce industrially, so it has not been possible to apply them to the production of amino resins. This is thought to be because it was impossible to think of it. The present invention will be explained in more detail below. The cationic group contained in the cationized PVA used in the present invention refers to at least one type selected from primary amine, secondary amine, tertiary amine, quaternary ammonium salt, pyridine, pyridinium, imidazole, or imidazolinium. Indicates a cationic group.
These are chemical structural units that dissociate in an aqueous solution and become positively charged. The methods for producing cationically modified PVA that have been reported so far include copolymerizing vinyl pyridine and vinyl acetate followed by saponification;
A method in which N-vinylphthalimide or N-vinylsuccinimide and vinyl acetate are copolymerized and then saponified, and the imide group is further decomposed with an alkali or hydrazine. A method in which PVA is converted into aminoacetal or aminobenzacetal under an acid catalyst. , PVA with alkoxydimethylamine, glycidyltrimethylammonium hydrochloride or 3-
Known methods include a method in which chloro-2-hydroxypropyltrimethylammonium hydrochloride is reacted, and a method in which acrylamide is added to PVA and then an amino group is introduced by Hofmann decomposition. Cation-modified compounds synthesized by these methods
Although PVA can also be used in the production of the amino resin composition of the present invention, the above-mentioned method for producing cation-modified PVA has various problems in the cationization step itself in order to be carried out industrially. In contrast, the following general formulas (), (),
Modified polyvinyl alcohol containing the copolymerized units shown in () or () not only exhibits cationic activity, but also has a stable and easy industrial method for introducing cationic groups and obtaining a desired degree of saponification. It is possible. (Here, R ¹ and R ² are hydrogen atoms or lower alkyl groups, and B is

[expression] or

[Formula] R ³ , R ⁴ , R ⁵ are hydrogen atoms or lower alkyl groups (which may contain substituents),
represents an anion, and A represents a group that connects with the nitrogen atom in B and the nitrogen atom of the amide group, respectively. ) (Here, R ⁶ , R ⁷ , and R ⁸ each represent a hydrogen atom, a lower alkyl group, or a phenyl group, R ⁹ represents a lower alkyl group, and X represents an anion.) (Here, B is

[expression] or

[Formula] R ³ , R ⁴ , R ⁵ are hydrogen atoms or lower alkyl groups (which may contain substituents),
represents an anion, and D represents an alkylene group connecting the nitrogen atom in B and the oxygen atom of the ether group. ) Modified PVA containing copolymerized units represented by the above general formulas () to () can be produced using vinyl esters, especially vinyl acetate, and the following formulas (a) to (d). (Here, the meanings of R ¹ , ² , R ⁶ to R ⁹ , X, A, B, and D are the same as above.) in the presence of a radical polymerization initiator. After copolymerization, the alcohol solution of the copolymer is treated with an alkali or acid catalyst to partially or highly saponify the vinyl ester units in the copolymer, depending on the purpose, to form vinyl alcohol units. It can be produced effectively and easily by. In the monomer represented by general formula (a), R ¹ is a hydrogen atom or a lower alkyl group, but a hydrogen atom or a methyl group is usually preferred, and furthermore, the polymerization rate in the copolymerization reaction with vinyl acetate is high. In this respect, a hydrogen atom is preferable. R ² is also a hydrogen atom or a lower alkyl group, but usually a hydrogen atom or a methyl group is preferred. B is an amino group

[Formula] or quaternary ammonium salt

[Formula] where R ³ , R ⁴ and R ⁵ represent a hydrogen atom or a lower alkyl group which may contain a substituent, and X represents an anion. R ³ , R ⁴ , and R ⁵ are all preferably methyl groups for normal purposes, but for special purposes, lower alkyl groups such as ethyl or propyl groups, or methylol groups or cationic groups are used for special purposes. Lower alkyl groups containing substituents such as aminoalkyl groups are also used for the purpose of improving density. X is a halogen atom such as chlorine, silium, iodine, or
CH ₃ OSO ₃ or CH ₃ C ₆ H ₄ SO ₃ is preferred, but
In particular, a chlorine atom is preferable from the viewpoint of economy, safety, or physical properties of modified PVA. When B is in the form of a quaternary ammonium salt, the effects of the present invention can be exhibited even with primary to tertiary amines, which are preferable for ease of handling in the production of modified PVA. As the group A that connects the nitrogen atom in the amino group B and the nitrogen atom of the amide group, any group containing a stable bond can be used, but a linear or branched aliphatic group is usually used. . Among the monomers represented by the above general formula (A), the following are specific examples of monomers in the form of tertiary amines. N-(2-dimethylaminoethyl)acrylamide, N-(2-dimethylaminoethyl)methacrylamide, N-(3-dimethylaminopropyl)acrylamide, N-(3-diethylaminopropyl)acrylamide, N-(3-dimethyl aminopropyl) methacrylamide, N-(3-
diethylaminopropyl) methacrylamide, N
-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide, N-(1,1-dimethyl-3-dimethylaminopropyl)methacrylamide, N-(1,1-diethyl-3-dimethylaminobutyl)acrylamide ,N-(1-methyl-
1,3-diphenyl-3-diethylaminopropyl)methacrylamide, N-(3-dimethylaminohexyl)acrylamide, N-(3-methylethylaminopropyl)methacrylamide, N-
Methyl-N-(3-dimethylaminopropyl)acrylamide. Among the monomers represented by the above general formula (a), those in the form of quaternary ammonium can be easily obtained by quaternizing the above-mentioned tertiary amine type monomer with the following quaternizing agent. be able to. Dialkyl sulfate, e.g. dimethyl sulfate, diethyl sulfate, dipropyl sulfate, C ₁ ~ of alkyl or arylsulfonic acid
C ₄ -esters, such as methyl-, ethyl-, propyl- or butyl esters, such as methanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid, benzyl halides, such as benzyl chloride or benzyl bromide, alkyl halides, such as methyl chloride. , methyl bromide, methyl iodide, ethyl chloride, ethyl bromide or ethyl iodide. The following four types of monomers among the various examples mentioned above as monomers represented by the above general formula (A). N-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide Trimethyl-(3-acrylamide-3,3-
dimethylpropyl) ammonium chloride N-(3-dimethylaminopropyl)methacrylamide Trimethyl-(3-methacrylamidopropyl)ammonium chloride is superior in producing the modified PVA of the present invention from the viewpoints of polymerization rate, stability of the amide group, and economic efficiency during monomer production. Further, examples of the monomer shown in (b) above include the following. 1-vinylimidazole, 1-vinyl-2-methylimidazole, 1-
Vinyl-2-ethylimidazole, 1-vinyl-
2-phenylimidazole, 1-vinyl-2,
4,5-trimethylimidazole. Further, the monomer represented by the above general formula (c) can be easily obtained by quaternizing the monomer represented by the above general formula (b) with the above-mentioned quaternizing agent. Examples of the monomer represented by the above general formula (2) include dimethylaminoethyl vinyl ether, dimethylaminopropyl vinyl ether, quaternized products thereof, and vinyloxyethylamine. The amount of cationic groups in the cationized PVA used in the present invention is required to be 0.01 to 10 mol%. The preferred range is 0.1-5 mol%. The saponification degree or polymerization degree is appropriately selected depending on the purpose and is not particularly limited, but the saponification degree is usually selected from the range of 60 to 100 mol%, and the polymerization degree is selected from the range of 300 to 3000. The cationized PVA used in the present invention is usually added to the resin component before or during the condensation reaction between the amino compound and the aldehyde.
It is effective to add 0.1 to 15% by weight. It is also effective to add cationized PVA to the amino resin solution after the condensation reaction, but in this case, compared to the method of adding it before the condensation reaction, it is necessary to add a larger amount to obtain the same effect. Generally speaking, it is economically disadvantageous. In the present invention, examples of the amino compound to be subjected to the condensation reaction include melamine, urea, thiourea, dicyandiamide, benzoguanamine, and acetoguanamine, and these may be used alone or in combination of two or more. can.
As the aldehyde, formaldehyde is used in the form of an aqueous solution or an alcoholic solution, and other compounds that can generate formaldehyde under condensation reaction conditions, such as paraformaldehyde, are also used. When the amino resin adhesive produced by the method of the present invention is made into a paste, conventionally known extenders and fillers, such as wheat flour, defatted soybean flour, and wood flour, may be mixed. The amino resin composition produced according to the method of the present invention has excellent storage stability when used as an adhesive, shows good fluidity even in winter, has excellent temporary adhesion during cold pressing, and has excellent adhesive properties when heated. It does not form a gel when heated, has excellent water resistance through heat curing, and has good washability of the size solution with water, so it has excellent cleaning workability. The reason why such excellent effects are obtained is not fully understood, but the cationized PVA, which is a feature of the present invention, constitutes one component of the amino-based resin, and has excellent stability, adhesive strength, and cleanability. This is thought to be because it has an effective effect. The above explanation has focused on adhesive applications, but the amino resin composition produced by the method of the present invention can be used in paper processing agents, fiber processing agents, paints, etc. by taking advantage of its stability and cationic activity. It is useful in a wide range of applications such as civil engineering and molded products. EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples in any way. Moreover, parts mean parts by weight. Example 1 (Urea-formalin resin) Trimethyl-(3-acrylamide-3,3-
Saponifying a copolymer of dimethylpropyl) ammonium chloride and vinyl acetate to form trimethyl-
(3-acrylamide-3,3-dimethylpropyl) Contains 2 mol% of ammonium chloride units, and the degree of saponification of vinyl acetate units is 98.5 mol%.
Cationized PVA with a viscosity of 30 cP (centipoise) in an aqueous solution at 20°C (as measured by a Bruckfield viscometer; the same applies hereinafter) was synthesized. Next, add 3 parts of the above cationized PVA powder to 268 parts of formalin (35.52%) and 45 parts of water, mix 1 part of urotropin and 100 parts of urea, and add aqueous solution of caustic soda (10%) at room temperature. After adjusting the pH of the mixture to 7.5, the mixture was heated with stirring and raised to 90°C over 30 minutes to start the condensation reaction. After raising the temperature to 90℃ and continuing the reaction at this temperature for another 80 minutes, the system (PH4 at this point)
A 10% aqueous sodium carbonate solution was added to adjust the pH to 7.5, and the mixture was cooled to room temperature to obtain a urea resin liquid. The stability test results of this resin liquid are shown in Table 1. Next, add 100 parts of the above urea resin solution, 20 parts of flour, and 13 parts of water.
A glue for adhering plywood was prepared by adding and mixing 1 part of ammonium chloride and 1 part of ammonium chloride, and the wood-to-wood adhesion strength and washability of the glue were evaluated and measured. The results are shown in Table 1. Examples 2 to 4 A urea resin liquid was produced in the same manner as in Example 1, except that the following cationized PVA was used in place of the cationized PVA in Example 1, and a sizing agent was also prepared in the same manner as in Example 1. . The evaluation results are shown in Table 1. The cationized PVA used in Example 2 contains 0.5 mol% of trimethyl-(3-methacrylamidopropyl)ammonium chloride units, and the degree of saponification of vinyl acetate units is 86 mol% and 4%.
Cationization of aqueous solution with viscosity of 27cP at 20℃
PVA. The cationized PVA used in Example 3 contains 1 mol% of 1-vinyl-2,3-dimethylimidazolinium chloride units, the degree of saponification of vinyl acetate units is 90 mol%, and the viscosity at 20°C of a 4% aqueous solution Cationized PVA with 29cP. The cationized PVA used in Example 4 contains 0.4 mol% of trimethyl-(vinyloxyethyl) ammonium chloride units obtained by saponifying a copolymer of trimethyl-(vinyloxyethyl) ammonium chloride and vinyl acetate, and saponified vinyl acetate units. 99.9 mol%, 4% aqueous solution of 20
Cationized PVA with a viscosity of 29 cP at °C. Comparative Examples 1 to 3 The following PVA was used in place of the cationized PVA of Example 1.
Alternatively, a urea resin liquid was produced in the same manner as in Example 1, except that modified PVA was used, and a sizing agent in the same manner as in Example 1 was also prepared. The evaluation results are shown in Table 1. The PVA used in Comparative Example 1 had a degree of saponification of 98.5 mol% and a 4% aqueous solution with a viscosity of 28 cP at 20°C. The PVA used in Comparative Example 2 had a saponification degree of 88 mol% and a 4% aqueous solution with a viscosity of 22.5 cP at 20°C. Modified PVA used in Comparative Example 3 A modified PVA containing 3 mol% of crotonic acid units, 99 mol% of saponification of vinyl acetate units, and a 4% aqueous solution having a viscosity of 25 cP at 20°C.

【table】

[Table] Example 5 (Urea-melamine-formalin resin) A copolymer of N-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide and vinyl acetate was saponified to produce N-(1,1-dimethyl -3-
A cationized PVA containing 1 mol% of (dimethylaminopropyl) acrylamide, a degree of saponification of vinyl acetate units of 88 mol%, and a 4% aqueous solution having a viscosity of 24 cP at 20°C was synthesized. Next, add 3 parts of the above cationized PVA powder to 317 parts of formalin (35.52%).
Add 1 part of urotropin, 50 parts of urea, and 50 parts of melamine to this mixture, and adjust the pH of the system to 7.5 by adding an aqueous solution of caustic soda (10%) at room temperature.
The temperature was raised to 75°C over 30 minutes with stirring, and the reaction was continued at this temperature for 50 minutes.
Add 10% sodium carbonate aqueous solution to 4.5) to adjust the pH.
After adjusting the temperature to 7.5, the mixture was cooled to room temperature to obtain a urea-melamine cocondensation resin liquid. The stability test results of this resin liquid are shown in Table 2. Next, add 100 parts of the above urea resin solution, 20 parts of flour, and 27 parts of water.
A paste for plywood adhesive was prepared by adding and mixing 1 part of ammonium chloride and 1 part of ammonium chloride, and the wood-to-wood adhesion strength and washability of the paste were evaluated and measured. The results are also shown in Table 2. Note that the bonding conditions, test conditions, etc. were carried out according to the notes in Table 1. Example 6 A resin liquid paste was prepared in the same manner as in Example 5, except that the cationized PVA used in Example 2 was used. The evaluation results are shown in Table 2. Comparative Examples 4 to 6 The following PVA was used in place of the cationized PVA of Example 5.
Alternatively, a resin liquid and a sizing agent were prepared in the same manner as in Example 5 except that modified PVA was used. The evaluation results are shown in Table 2. PVA used in Comparative Example 4: PVA with saponification degree of 98.5 mol%, viscosity at 20°C of 4% aqueous solution is 28 cP PVA used in Comparative Example 5: Saponification degree of 88 mol%, viscosity at 20°C of 4% aqueous solution Modified PVA used in Comparative Example 6: Modified PVA with 3 mol% crotonic acid units, 99 mol% saponification degree of vinyl acetate units, and a 4% aqueous solution with a viscosity of 25 cP at 20°C.

[Table] From the above results, it can be seen that the amino resin composition of the present invention has excellent stability, high adhesive strength, and extremely excellent water washability.

Claims (1)

[Scope of Claims] 1. During or after the condensation reaction between an amino compound and an aldehyde, from a primary amine, secondary amine, tertiary amine, quaternary ammonium salt, pyridine, pyridinium, imidazole or imidazolinium A method for producing an amino resin composition, which comprises adding cationized polyvinyl alcohol containing 0.01 mol% to 10 mol% of at least one selected cationic group. 2. The production method according to claim 1, wherein the cationized polyvinyl alcohol is a modified polyvinyl alcohol containing a copolymerized unit represented by the following general formula (). (Here, R ¹ and R ² are hydrogen atoms or lower alkyl groups, B is [Formula] or [Formula] R ³ , R ⁴ , and R ⁵ are hydrogen atoms or lower alkyl groups (which may contain substituents), is an anion, A is B
and a group connecting the nitrogen atom of the amide group and the nitrogen atom of the amide group, respectively. ) 3. The manufacturing method according to claim 1, wherein the cationized polyvinyl alcohol is a modified polyvinyl alcohol containing a copolymerized unit represented by the following general formula () or (). (Here, R ⁶ , R ⁷ , R ⁸ are hydrogen atoms, lower alkyl groups or phenyl groups, R ⁹ is lower alkyl groups,
Each X represents an anion. ) 4 The manufacturing method according to claim 1, wherein the cationized polyvinyl alcohol is a modified polyvinyl alcohol containing a copolymerized unit represented by the following general formula (). (Here, B is [Formula] or [Formula] R ³ , R ⁴ , R ⁵ is a hydrogen atom or a lower alkyl group (which may contain a substituent),
represents an anion, and D represents an alkylene group connecting the nitrogen atom in B and the oxygen atom of the ether group. )