JPS5819378A - Water-base adhesive - Google Patents

Abstract

PURPOSE:To provide a water-base adhesive which contains a cationic water-base polyurethane, a polyvinyl acetate emulsion and an epoxy resin, has excellent heat-resistant adhesiveness, thermal creep resistance resistance to solvent and water, etc. and is suitable for bonding plastic sheets, etc. CONSTITUTION:The adhesive is obtained by mixing (a) cationic water-base polyurethane, (b) polyvinyl acetate emulsion and (c) epoxy resin (e.g. bisphenol A type epoxy resin) in the blend ratio of 1-60:98.5-20:0.5-20 by solid weight and adjusting the pH value to 7 or lower. (a) is obtained, e.g., by adding an alkylating agent to a solvent solution of a polyurethane consisting of a polyol, a polyisocyanate and a tertiary N atom-contg. chain extender, for quaternization and mixing the quaternized polyurethane solution with water. USE:Bonding of cellulosic materials such as paper, fiber and wood, inorganic materials such as concrete, plastic materials, metals such as Al, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new and useful water-based adhesive, and more particularly, it has excellent solvent resistance, water resistance, adhesion, and heat creep properties; The present invention relates to an aqueous adhesive mainly composed of aqueous cationic polycrethane, polyvinyl acetate emulsion, and epoxy resin in a specific mixing ratio, which has excellent other adhesion properties such as initial adhesion. - Polyvinyl acetate emulsions, especially ethylene-vinyl acetate copolymer emulsions, are widely used as adhesives for adherends such as paper, plastic films, and plastic sheets, but the use of adhesives is becoming more widespread. As adhesives become more demanding, the performance requirements for adhesives become more severe, and conventional ethylene-vinyl acetate copolymer emulsions are no longer able to satisfy these performance requirements. For example, recent attempts have been made to manufacture high-grade painted decorative plywood by coating the surface of PVC plywood with solvent-diluted polyurethane resin, unsaturated polyester resin, etc., but conventional ethylene-vinyl acetate conjugate Emulsions are still impractical because the adhesive layer is damaged by the solvent in the paint or the styrene monomer in the unsaturated polyester resin, causing peeling or blistering at the interface between the PVC sheet and the plywood. .

In addition, plywood laminated with embossed PVC sheets is often used as an interior material, and in areas where there is a lot of water or humidity around the washing area, adhesiveness is likely to decrease and blisters may occur. The current situation is that a problem is occurring. However, in view of the above circumstances, the present invention provides a water-based adhesive that has excellent heat-resistant adhesive properties, heat-resistant creep properties, solvent resistance, water resistance, etc. for adherends such as plastic coats or films. As a result of intensive research, it was found that a water-based adhesive with a pH of 7 or less, which is mainly composed of a mixture of cationic water-based polyurethane, polyvinyl acetate emulsion, and epoxy resin in a specific ratio, is extremely effective. This discovery led to the completion of the present invention.

That is, the present invention is a water-based adhesive mainly composed of cationic water-based polyurethane, polyvinyl acetate emulsion, and epoxy resin, and the solid content ratio of these kings is 1.
~60:9&5~20:Q, 5~20, and p
The present invention provides a so-called acidic aqueous adhesive having H of 7 or less.

Here, the above-mentioned cationic water-based polyurethane, which is the first component of the adhesive of the present invention, is a general term for water-soluble or water-dispersible water-based polyurethanes containing one or more types of cationic nitrogen atoms. For example, ionizable nitrogen atoms are introduced into the main chain, side chains, or terminals of polyurethane, and some or all of these nitrogen atoms are cationized with an acid or an alkylating agent. Possible nitrogen atoms are 3
Class or quaternary nitrogen atoms are particularly advantageous in the production process of the aqueous polyurethane.

Next, typical examples of the production method of the cationic water-based polyurethane used in the present invention will be given, but the production method is not limited to these.

Dennatsu) A method of obtaining a water-based polyurethane by adding an alkylating agent to a solvent solution of a polyurethane consisting of a polyol, a polyincyanate, and a tertiary nitrogen-containing chain extender to quaternize it, and then mixing this with water.

(A method for obtaining an aqueous polyurethane by adding anhydrous acid to a urethane prepolymer having a terminal incyanate group consisting of a 215th grade nitrogen-containing polyol and a polyincyanate to neutralize it, and then mixing it with water to obtain an aqueous polyurethane, Nishiki) Polyol, A method for obtaining an aqueous polyurethane by mixing a urethane polymer consisting of a polyincyanate and a tertiary nitrogen-containing chain extender with an acid aqueous solution, (4) a method consisting of a polyol, a partially blocked polyincyanate, and a tertiary nitrogen-containing chain extender. A urethane prepolymer is reacted with an alkylating agent to quaternize it, and then mixed with an aqueous diamine solution. A method for obtaining an aqueous polyurethane by mixing an acid aqueous solution with a polyurethane consisting of a polyol and a polyincyanate, and (6) reacting a urethane prepolymer consisting of a polyol and a polyincyanate with an excess of polyamine, and further producing a quaternary polyurethane with an ebihalohydrin and a trialkylamine. Examples include a method in which nitrogen atoms are introduced and mixed with water to obtain water-based polyurethane.

A small amount of emulsifier may be added during the production of such cationic aqueous polyurethane. The emulsifier is preferably a nonionic surfactant such as an alkylene oxide adduct, or a cationic surfactant such as a long-chain alkylamine salt. Further, a solvent that dissolves in polyurethane, such as acetone, ethyl acetate, methyl ethyl ketone, or toluene, may be included as long as the aqueous properties of the cationized polyurethane are not impaired.

As shown in the above-mentioned production method example, when obtaining a cationic water-based polyurethane, first, a compound containing an ionizable nitrogen atom and also a reactive hydrogen atom is used as a component of the polyurethane.

Representative examples of such compounds include the following.

(a) N--r alkyl dialkoxylated amines: such as tfN-methylgetanolamine, N-ethylgetanolamine, N-propylgetanolamine, N-
Improvir diethanolamine, N-butylgetanolamine, N-imbutylgetanolamine, N-
Oleylgetanolamine, N-stearylgetanolamine, ethoxylated amine of coconut oil, N-allylgetanolamine, N-methyldiimpropanolamine, N-ethyldiinpropanolamine, N-butyldiinpropanolamine or N -Cyclohexyldiynepropanolamine (b) N,N-jethoxyaniline, N,N-jethoxy-α-aminopyridine, N,W-diethoxybipe2dine, dimethyl-bis-ethoxy-hydrazine, N,N'
-bis-(β-hydroxyethyl)-N,N'-diethyl-hexahydro-P-phenylenediamine or N-
β-Hydroxyethylbipetudine (-) Polyalkoxylated amines: e.g. propoxylated methyljetanolamine (d) N-methyl-N, N-bis-γ-aminopropylamine, N-(r-aminobouyl)-N , N'-
Dimethylethylenediamine, N-(r-aminobouvil)-N-methylethanolamine, N,N'-bis-
(r-aminopropyl)-hiverazine, N,N'-bis-ethoxypropylenediamine, 2,6-diamitubiridi/, jetanolamine acetamide, jetanolamine propionamide, N,N-bis-ethoxyphenyl-thio Semicarbazide, N,N-bis-ethoxymethyl semicarbazide or P-P'-bis-aminomethyl dibenzylamine (.) Tertiary nitrogen-containing monools: e.g. dimethylethanolamine, diethylethanolamine, dimethyl imp, lovanolamine or diethyl inpropanolamine O. On the other hand, as the polyincyanate, any aromatic,
Aliphatic and cycloaliphatic diincyanates are also applicable, and the following are typical among them.

1.5-Naphthylene diincyanate, 4,4
'-diphenylmethane diincyanate, 4,4'-diphenyldimethylmethane diincyanate, di- and tetra-alkyldiphenylmeth/diincyanate),
Each isomer of 4.4'-dibenzyl diincyanate, 1,3-phenylene diincyanate, 1.47 phenylene diincyanate, and toluylene diincyanate (
and optionally a mixture of said isomers); 1-methy)v-2,
4-diincyanatocyclohexane, 1,6-cyincyanate)-2,2,4-)limethylhexane, cyclohexane-1,4-diincyanate, dicyclohexylmethane diisocyanate, 1-incyanatomethyl-3-incyanate) -1,5,5-trimethylcyclohexane: chlorinated and brominated diincyanate; phosphorus-containing diincyanate: 4,4'-diincyanate-phenyl-perfluoroethane; tetramethoxybutane-1,4-diincyanate, Butane-1
, 4-diincyanate, hexane-1,6-diincyanate, ethylene diisocyanate; p-xylylene diisocyanate, m-xylylene diisocyanate, and hydrogenated products of each of the above aromatic diisocyanates. , reaction products of excess amounts of these diisocyanates with water, diamines, glycols, polyalcohols or aminoalcohols, or compounds containing a tertiary nitrogen atom and also having a reactive hydrogen atom.

Further, as the polyamine, compounds having amino groups at both ends and an -NH- group in the main chain can be used, typical examples of which include diethylenetriamine,
Polyalkylene polyamines such as dipropylene triamine or tetraethylene diamine.

Furthermore, the polyol has a relatively high molecular weight having a reactive hydrogen atom at the end; for example, a molecular weight of 200 to 20.
Examples include polyethers, polyesters, polyester amides, polyacetals, polythioethers, polyamides, and polybutadiene glycols in the ODD range. Further, as a tertiary nitrogen-containing polyol, a compound containing a tertiary nitrogen atom and also a reactive hydrogen atom is reacted in combination with a relatively high molecular weight polyol, or, for example, an ester reaction, an ether reaction, etc. It may also be obtained by incorporating it into a polymer polyol by applying an elementary reaction such as chemical reaction or amidation reaction.

For chain extension stabilization, relatively low molecular weight compounds having reactive hydrogen atoms can be used, such as glyconyls, aliphatic, cycloaliphatic and aromatic diamines, amino alcohols, etc. , water or a compound containing a 5th class nitrogen atom and also having such a reactive hydrogen atom.

Examples of alkylating agents used for cationizing polyurethane include the following.

Methyl chloride, methyl bromide, methyl iodide, ethyl bromide,
Propyl bromide, butyl bromide, dimethyl sulfate, diethyl methyl sulfate/chloromethyl ether, methyl-1,2-dichloroethyl ether, ethyl chloromethyl ether, benzyl chloride, benzyl bromide, ethylene chlorohydrin, epichlorohydrin, ethylene oxide , propylene oxide, styrene oxide, ethyl benzenesulfonate, chloroacetic acid, glycol monobromoacetic acid esters, glycerin monochloroacetate, bromoethyl ester of acetic acid, 1゜4-dibromobutane or p-
Examples include cycrylene dichloride.

Similarly, as the acid used for cationization of polyurethane, ordinary acids can be used, but representative ones include hydrochloric acid, sulfuric acid, sulfurous acid, hydrobromic acid,
Inorganic acids such as hydrofluoric acid, phosphorous acid, hypophosphorous acid, fluoroboric acid, amidosulfonic acid, phosphoric acid and its derivatives; and organic acids such as tartaric acid, oxalic acid, lactic acid, formic acid, acetic acid and acrylic acid. Carboxylic acids can be given.

On the other hand, the polyvinyl acetate emulsion which is the second component of the adhesive of the present invention is a vinyl acetate polymer emulsion; or a combination of vinyl acetate monomer and one or more other monomers. It is also possible to use copolymer emulsions in which the vinyl acetate monomer accounts for 50% or more in the weight composition; it is also possible to use mixtures of these emulsions. Here, typical examples of the above-mentioned other monomers include alkyl esters of (meth)acrylic acid, ethylene, propylene, vinyl chloride, and (meth)acrylic acid.

The polyvinyl acetate emulsion can be obtained by emulsion polymerization using a conventional method. As the surfactant or protective colloid used in this case, it is preferable to use a nonionic or cationic surfactant, but on the contrary, a surfactant or an anionic surfactant will impair the stability of the aqueous adhesive of the present invention. This is not desirable.

Next, the epoxy resin which is the third component of the adhesive of the present invention includes compounds having two or more epoxy groups in the molecule, which are usually commercially available, and there are no particular restrictions on the epoxy resin. Any known and commonly used resins can be used, among which typical examples include bisphenol large epoxy resins, polyalkylene ether type epoxy resins, glycerin type epoxy resins, and alicyclic epoxy resins.

The composition ratio of the water-based adhesive of the present invention is mainly composed of cationic water-based polyurethane, polyvinyl acetate emulsion, and epoxy resin, as described above, in terms of solid content weight ratio.
'MSO: 98.5-20: α5-20, preferably 5
A suitable range is 50:94 to 40:1 to 10.

Among these, if the composition ratio of cationic water-based polyurethane and epoxy resin is smaller than 1 and 0.5, respectively, the desired adhesive performance such as solvent resistance, water resistance, adhesion, or heat-resistant creep cannot be obtained. On the other hand, if the viscosity of the adhesive is greater than 60 or 20, it becomes difficult to control the viscosity of the adhesive, the initial adhesion properties may actually deteriorate, and it is also economically disadvantageous, which is undesirable. .

Among the main components of the present invention, cationic water-based polyurethane and polyvinyl acetate emulsion are generally mixed as is in a specific ratio, but cationic water-based polyurethane prepared in advance can be used as a mixture. The epoxy resin, which is the third component of the adhesive of the present invention, can also be added to a polyvinyl acetate emulsion to cause a grafting reaction between them. If mixed with the system emulsion, the stability of the blended liquid itself will deteriorate, so it is preferable to mix it before use.

The aqueous adhesive of the present invention needs to have an acidic PR of 7 or less, and more preferably has a pH of 2 to 6. p)
On the so-called alkaline side, where ( is greater than 7), the adhesive may gel after preparation, change in viscosity, or deteriorate adhesive performance due to heat-resistant creep, which is disadvantageous.

Other compounding agents conventionally used in polyvinyl acetate emulsion adhesives can be added to the aqueous adhesive of the present invention thus obtained, if necessary. Typical examples of such compounding agents include solvents such as toluene, xylene, chlorobenzene, trichloroethylene, butyl acetate, or butylselonulp; polyvinyl alcohol, cellulose I conductors such as hydroxyethylcellulose, casein, polyvinylpyrrolidone, and polyvinylalcohol. Water-soluble polymeric substances such as alkylene ether, poly'amide, polyacrylamide or polyamine: DBP
Or plasticizers such as DOP; tackifiers such as terpene resins; or inorganic fillers and pigments.

The water-based adhesive of the present invention can be applied to cellulose materials such as paper, fiber or wood; inorganic materials such as concrete or silica boards; plastic materials such as vinyl chloride and polystyrene; metal materials such as aluminum; and many other materials. Can be used as an adhesive for

EXAMPLES Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 4 and Comparative Examples 1 to 2 Aqueous cationic polycretanes were used as Hytran He-400J (solid content 50%,
BM type viscosity at 25°C (the same applies below) 1,900 cp
s, pH 4.1] was converted into an ethylene-vinyl acetate emulsion using "Evadic EP-11" manufactured by Dainippon Ink & Chemicals (solid content 53%, viscosity 6,000).
ep@, a milky white liquid with a pH of 4.2) was used as an epoxy resin by Dainippon Ink & Chemicals [Evicron 5so-
[
Ebicuron 1050-90XJ (a transparent liquid using Kijiroru as a solvent with a solid content of 90% and a viscosity of ?1-C1, C100 cps) was mixed in the proportions listed in Table 1, and 3% toluene was added to bond. A drug was prepared.

For comparison, a commercially available ethylene vinyl acetate emulsion adhesive (solid content 51%, viscosity 1 to 000 cps,
Using a milky white liquid with a pH of 4.8), apply each of these adhesives to JAS Class I lauan plywood (100 to 120 II).
/ m” and coated with a polyvinyl chloride sheet (hard,
A soft and embossed mold) was pasted, pressed at a pressure of 0.05 to 9/e- for 16 hours, and then the pressure was removed and allowed to cure for one week, before being subjected to the next test. However, regarding the initial adhesion, the test was carried out by simply pressing the same materials together for 5 hours after bonding them together.

Normal adhesion test At room temperature, test piece with width 25111I at speed 200m/
This was determined by conducting a 1806 peel test in minutes.

A test piece of polyvinyl chloride sheet with a width of 25 m x 200 m was first peeled 50 m in the vertical direction, and then the test piece was placed horizontally and the peeled polyvinyl chloride sheet was held vertically at 90°C. A load of 500I was applied to the tip of the polyvinyl chloride sheet, the lid was opened, and the peeled length was measured after 30 minutes. This shows that the heat resistance creep property is good.

Adhesion test The polyvinyl chloride sheet was peeled off at 90° from a test piece with a width of 25 cm at speeds of 2 m/sec and 50 fins/sec, respectively, and observed and determined. If there is no specular peeling between the two, it has good adhesion. In addition, this adhesion test is conducted in two ways: ■ When the test piece is immediately tested at 23°C, and ■ -
Two cases were tested: a case where the sample was left at a temperature of 5° C. for 20 hours; and a case where the sample was left for 20 hours.

■When laminated at 5℃ and pressed for 5 hours at the same temperature and 023
Peeling the polyvinyl chloride sheet at 90 degrees at speeds of 2 m/sec and 50 m/sec, respectively, from test pieces with a width of 25 cm cut from each PVC plywood sheet when laminated at ℃ and pressed at the same temperature for 5 hours. As determined by observation, good adhesion is observed when there is no specular peeling between the polyvinyl chloride sheet and the adhesive layer.

Water resistance test■ This was observed and judged in accordance with the JAS Class I immersion peel test.On the other hand, the adhesive strength after water resistance was determined by applying a 25wM width test piece to 2DCb180 in a wet state after immersion.
°It was determined by performing a peel test.

■ Observations and judgments were made in accordance with the Water Resistance A Test of JAS Ministry of Agriculture, Forestry and Forestry Notification No. 1373.

Solvent resistance test ■ Unsaturated polyester resin 11 was placed on PVC plywood, covered with a glass Petri dish, and left overnight. The surface condition was then observed and judged. The results are shown in section K of "Spot test". Summarized.

■ PVC plywood is processed into a corrugated shape as shown in Figure 1, and then a polycrethane resin solution is applied to the processed plywood.
The surface condition of the decorative PVC plywood coated with unsaturated polyester resin was then observed and judged, and the results are summarized in the section ``Corrugated processing test''.

[Brief explanation of drawings]

Figure 1 is a partially enlarged perspective view showing the structure of corrugated PVC plywood as an example of the sample used in the corrugation test in the solvent resistance test, and at the same time shows the condition that is the basis for determining the test results. It shows. 1... Plywood 2... PVC sheet a... Blistering

Claims (1)

[Claims] The main components are cationic aqueous polycrethane, polyvinyl acetate emulsion, and epoxy resin, respectively, 1 to 60:9 & 5 to 20: α5 to 20 (solid content weight ratio).
1. A water-based adhesive characterized by comprising: a pH of 7 or less;