JPS6133875B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high-frequency adhesive in the form of a slurry. More specifically, the present invention relates to a slurry-like high-frequency adhesive that has a specific monomer composition, easily wets metals, glass, wood, fibrous materials, etc., and has a practical high-frequency adhesive strength that is easy to adhere to. Conventionally, there have been high frequency adhesives in the form of soft vinyl chloride resin films or low melting point polyamide films, and high frequency adhesives in the form of films made from vinyl chloride resin latex or vinylidene chloride copolymer latex. Recently, high-frequency adhesives made of vinyl chloride resin powder and low-melting point polyamide resin powder have been developed, but they have too little dielectric loss, low high-frequency adhesive strength, contain plasticizers, and are difficult to apply. However, there is no high-frequency adhesive that is sufficiently practically satisfactory. High-frequency adhesives have attracted particular attention in recent years because they have the following three major advantages. Before adhesion, it is easy to store and handle as a film or powder. When bonding, apply high frequency voltage for a short time (30 seconds to 1 minute)
Adhesion can be achieved simply by applying a voltage, and in principle, the adhesive force can be arbitrarily controlled by the application time of the high-frequency voltage, the contact pressure, and the contact pressure temperature. The high frequency bonding process is easy to automate and can easily be inlined or roboticized into various continuous assembly processes. Recent advances in solid-state high-frequency generators and their electronic control mechanisms have made them smaller, more precise, and more reliable. High-frequency bonding machines have become smaller and cheaper, and have become popular as they are incorporated in-line into various continuous bonding processes. I've been doing it. For example, the application of a high-frequency bonding machine to a process of continuously manufacturing adhesive structures that are produced in small quantities at high speed in small quantities, or adhesive structures that are produced in large quantities in small quantities at high frequencies is extremely effective. Examples of specific products for which such a high-frequency adhesive machine is effective are: Plywood, laminated wood, unit furniture, structures in which dissimilar materials are bonded or temporarily bonded to steel, concrete, and wood, such as honeycomb boards, interior decoration (automobiles), etc. For example, there are composite assemblies such as ceiling materials, wall materials, carpets, seats, doors, etc. (interior materials, ship interior materials, aircraft interior materials). Adhesives suitable for high-frequency adhesive machines essentially generate dielectric heat due to the applied high-frequency electric field.
It must be a material that melts or softens, or crosslinks and hardens. In order to generate this dielectric heat generation, dielectric loss is important depending on the applied frequency. On the other hand, it is common knowledge when using adhesives that if the wetting with the adhered material is not sufficient, peeling will occur at the adhesive interface and the desired adhesive force will not be obtained. Examples of materials that generate high-frequency dielectric heat generation include polyvinyl chloride resin, polyvinylidene chloride resin, and polyamide resin; examples of the latter include phenol, urea, resorcinol,
Melamine resins are known. The former type of adhesive that generates high-frequency dielectric heat is generally used in the form of a film or a film coated with latex. In recent years, powdered products have been developed. The latter high-frequency dielectrically heated adhesive is generally used in the form of an aqueous or alcoholic solution or a suspension in a water or alcoholic medium. Although the thermosetting high frequency adhesive has excellent adhesive strength, it essentially has the following four drawbacks. (1) It is a wet type containing a large amount of water or alcohol, making it difficult to handle and store. (2) A large amount of water or alcohol must be evaporated, a long drying process is required, and a large amount of drying energy is required. Therefore, the drying speed is slow and productivity is low. (3) Alcohol-based systems have faster drying speeds than water-based systems, but they have problems in terms of fire, environmental pollution, and health and safety. (4) Since it is a wet type, it is difficult to incorporate it into an inline system. Thermoplastic high frequency adhesives are superior to adhesives because they are essentially dry, but they have the following four drawbacks. (1) It is difficult to position the film-like adhesive and the material to be adhered, and there is a problem that the positioning may shift with a slight external force. (2) Powder-like adhesives move or slide off with slight vibrations on materials with smooth surfaces, making it difficult to adhere them at a predetermined bonding location. (3) It is difficult to automate the process of inserting film and powder when manufacturing complex assemblies and structures, and it is difficult to incorporate it as an in-line system. (4) Nylon film has low wetting properties and is prone to interfacial peeling, and polyvinyl chloride and polyvinylidene chloride are easily altered in the film formation process, requiring the use of plasticizers, etc., to improve wetting with the adhered material. There are limits, and peeling at the adhesive interface may occur. Eliminates the drawbacks and difficulties associated with thermoplastic film or powder high frequency adhesives regarding positioning and wetting with adhered materials, and eliminates the drawbacks of wet type thermosetting high frequency adhesives. In addition, there was a demand for a high-frequency adhesive that could be easily bonded. The following five basic performance requirements are listed below. (1) It is in the form of a slurry with high solids content. (2) An adhesive whose adhesive layer is dry when bonded. (3) There is no loss and the adhesive can be reused. (4) The adhesive can be easily incorporated into in-line systems. (5) It is an adhesive whose wetting with the material to be adhered can be easily controlled. In response to the above requirements, as a result of intensive research, the present inventors were able to provide a high frequency adhesive in the form of a slurry made of a vinylidene chloride copolymer that satisfies the above basic required performance. That is, according to the present invention, vinylidene chloride component A of 20 mol % or more and 93 mol % or less and one or more monomers selected from monomers copolymerizable with component A and 7 mol % or more and 80 mol % or less A vinylidene chloride copolymer consisting of component B and a monomer component C selected from 0 mol% or more and 10 mol% or less of a functional monomer copolymerizable with component A and/or component B, and the polymer powder The effective particle size of
0.5μm or more and 1mm or less and 5% by weight of the powder
As described above, it was possible to provide a slurry-like high-frequency adhesive in which 80% by weight or less is suspended in a dispersion medium of 20% by weight or more and 95% by weight or less. Specific requirements of the invention and examples thereof are shown below, but the invention is not limited only to the contents thereof. As a method for manufacturing the adhesive of the present invention, known suspension polymerization methods, emulsion polymerization methods, solution polymerization methods, and mass polymerization methods can be employed. The emulsion polymerization method using a water-soluble radical initiator is preferable because it can introduce sulfuric acid groups, sulfite groups, hydroxyl groups, etc. made of decomposition products of the radical initiator into the copolymer terminals, and it is possible to impart functional groups to the copolymer terminals. . The emulsion polymerization method is also preferable to the suspension polymerization method because it allows functional monomer components such as acrylic acid, methacrylic acid, glycidyl methacrylic acid, and 2-hydroxylethyl acrylate to be introduced into the copolymer with good control. In the suspension polymerization method using an oil-soluble radical initiator, not only the terminal of the copolymer is a non-functional group, but also the functional monomer component C tends to be controlled and difficult to introduce. In solution polymerization and mass polymerization using an oil-soluble radical initiator, it is necessary to remove a large amount of residual monomer from the copolymer. Copolymers produced by emulsion polymerization as a powder manufacturing method can be produced by chemical salting out in the presence of a salting out agent, physical salting out under mechanical shearing force or temperature changes, hot air drying, infrared drying, A combination of known methods such as microwave drying can be used. After this, a conventional pulverizer is used to make the particle size uniform, and a sieve can also be used. As monomer B copolymerizable with vinylidene chloride, α-monosubstituted unsaturated ethylenic monomers and unsaturated carboxylic acid ester monomers can be used. Preferably, a mixture of one or more selected from vinyl chloride, vinyl acetate, vinyl methyl ether, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, acrylonitrile, methacrylonitrile, etc. Can be used. More preferred are vinyl chloride, vinyl acetate, methyl acrylate, ethyl acrylate, butyl acrylate, and acrylonitrile because they are inexpensive. Vinylidene chloride A and/or monomer B
As the functional monomer C copolymerizable with the monomer selected from unsaturated monocarboxylic acids, dicarboxylic acids, α-alkyl-substituted unsaturated carboxylic acids, amides of these acids, hydroxy-substituted alkyl esters, glycidyl-substituted esters, or their Mixtures etc. are used. Preferably acrylic acid,
Methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, acrylic acid amide, methacrylic acid amide, hydroxyethyl acrylate are used. More preferably, acrylic acid, methacrylic acid, acrylic amide, methacrylic amide, itaconic acid, hydroxyethyl acrylate, and glycidyl methacrylate are easily available industrially. The composition of vinylidene chloride A component, B component monomer, and functional monomer C component is vinylidene chloride 20 mol% or more and 93 mol% or less, B component monomer 7 mol% or more and 80 mol% or less, and C component monomer as 0 mol. % or more and 10 mol% or less is preferable. Preferably, vinylidene chloride is 35 mol% or more and 90 mol% or less, B component monomer is 10 mol% or more and 65 mol% or less, and C component monomer is 0.1 mol% or more and 8 mol% or less. More preferably 40 mol% or more of vinylidene chloride,
85 mol% or less, B component monomer 16 mol% or more, 60
mol% or less, C component monomer 0.5 mol% or more, 5
It is less than mol%. If vinylidene chloride is less than 20 mol %, high frequency dielectric heat generation is small, the adhesive is not sufficiently melted or softened, and practical adhesive strength cannot be obtained, which is not preferable. If vinylidene chloride exceeds 93 mol%, the high frequency dielectric heat generation will decrease again, and the crystallinity of the copolymer will become too high, and the adhesive will not melt or soften sufficiently, making it impossible to obtain practical adhesive strength, which is undesirable. .
The introduction of functional monomer component C is preferred in order to further improve adhesive strength. Amount of functional monomer C introduced
At 0.05 mol% or more, a clear effect of increasing high frequency adhesive strength is observed. For example, for adhesion of structural materials such as adhesion of laminated plywood, metal to metal, or adhesion of metal to other materials such as plywood, paperboard, hardboard, etc., functional monomer components and/or copolymer terminals can be used. Preferably, there is a functional group. Furthermore, in the present invention, component D may be used as a thickener. The amount of component D added varies depending on the viscosity of the slurry-like high-frequency adhesive. For example, when acrylic copolymer latex, vinyl acetate copolymer latex, and ethylene copolymer latex are used together, they are thickened and will not sag when applied to the bonded material, so component D should not be added. no longer necessary. When vinylidene chloride copolymer latex and vinyl chloride copolymer latex are used together, it is difficult to increase the viscosity, so it is necessary to add component D as a thickener. In order to substantially prevent sagging on the surface of the bonded material, the viscosity (B-type viscometer at 6 rpm) is preferably 1000 cps or more and 30000 cps, and the required amount of thickener added is 0.05% by weight or more and 10% by weight or less. is preferred. The effective particle size range of powder adhesive is 0.5
A diameter of μm or more and 1 mm or less is preferable because it is easily dispersed in a dispersion medium. Preferably it is 1 μm or more and 500 μm or less, more preferably 5 μm or more and 300 μm or less. When the above particle size range is displayed using a JIS standard sieve, it is 16
The mesh pass is preferably 32 mesh passes, and more preferably 48 mesh passes. Particles smaller than 0.5 μm are undesirable because they cause secondary aggregation when made into a slurry-like high-frequency adhesive, causing lumps. Particles larger than 1 mm have the disadvantage that slurry-like high-frequency adhesives tend to cause layer separation. Vinylidene chloride copolymer powder mixed with vinyl chloride copolymer and/or low melting point polyamide resin powder can also be used. Preferred vinyl chloride copolymers for blending include vinyl chloride-vinyl acetate and/or ethylene copolymers or vinyl carboxylic acid-modified vinyl chloride-vinyl acetate and/or ethylene copolymers, which are preferred as low melting point polyamide resins. Nylon resin powder below 180℃ is good. A high-frequency adhesive in the form of a slurry in which a mixture of these is suspended in a dispersion medium is effective in reducing costs and improving low-temperature strength and high-temperature strength. As the dispersion medium used in the present invention, water, a water-dispersible latex, an aqueous solution, and/or an organic solvent can be used. As the dispersion medium, water, water-dispersible latex, or an aqueous solution is preferable since there is no risk of fire or environmental pollution. Thermoplastic resin latexes commercially available as water-dispersible latexes, such as vinylidene chloride copolymer latex, vinyl chloride copolymer latex, ethylene copolymer latex, vinyl acetate copolymer latex, acrylic copolymer latex, and rubber latex. For example, butadiene copolymer latex, chloroprene copolymer latex, isoprene copolymer latex, natural rubber latex, etc. may be used alone or as a blend.
Preferably, vinylidene chloride copolymer latex and vinyl chloride copolymer latex are preferable because they themselves generate high-frequency dielectric heat when solidified, and ethylene copolymer latex, vinyl acetate copolymer latex, and acrylic copolymer latex have thickening properties. The stability of the slurry is good. As an aqueous solution or dispersion of thermosetting resin, commercially available aqueous solution or dispersion of phenol, melamine, resorcinol, or urea, or a thermally crosslinkable acrylic copolymer latex, or a high-frequency adhesive in the form of a slurry for plywood or laminated wood. preferred as a dispersion medium. The slurry composition of the copolymer powder and dispersion medium is preferably 5% by weight or more and 80% by weight or less of the copolymer powder, and 20% by weight or more and 95% by weight or less of the dispersion medium. Preferably, the powder is 10% by weight or more and 75% by weight or less, and the dispersion medium is 25% by weight.
The amount of the copolymer powder is preferably 15% to 70% by weight, and the dispersion medium is preferably 30% to 85% by weight. If the copolymer powder is less than 5% by weight, it is essentially a latex, and the advantages of increasing the solid content of the adhesive cannot be taken advantage of. occurs, which is not desirable. Furthermore, the slurry-like high-frequency adhesive according to the present invention not only satisfies the five basic required performances described above, but also has the following advantages when compared with the powder-like high-frequency adhesive. It is easy to temporarily attach it to materials to be adhered, especially to materials with flat surfaces such as wood and metal. (On the other hand, powdered high-frequency adhesives are convenient because they adhere without spilling when impregnated into the framework of porous materials, but when applied to objects with flat surfaces, they adhere only by electrostatic force. (It is impossible to attach a large amount of adhesive to the surface.) Since it is easy to attach, a large amount of adhesive can be attached to the surface. In particular, by using latex or thickening it, a predetermined amount can be reliably attached to the surface. (Powdered adhesives have a small amount of adhesion.) Only slurry-like high-frequency adhesives can be used in combination with thermally crosslinkable resins. The combined use of a thermally crosslinkable resin is advantageous when used as a heat-resistant or structural adhesive. In this case, it is estimated that the thermal crosslinking reaction is accelerated by high frequency dielectric heat generation of the high frequency adhesive resin powder component. (On the other hand, powdered adhesives cannot be used in combination with powdered thermally crosslinkable resins.
Mixing is difficult, and the crosslinking reaction is a solid phase reaction, so strength cannot be expected. ) Example 1 A copolymer of 85 mol% vinylidene chloride, 15 mol% acrylonitrile, and 0.04 mol% itaconic acid, with a functional group component formed from a decomposed component of a sodium persulfate initiator at the molecular end. , vinylidene chloride copolymer powder (component A) with a particle size of 20 mesh pass JIS sieve (component A), vinylidene chloride component 75 mol%, vinyl chloride component 17 mol%,
Acrylonitrile component 8 mol%, acrylic acid component
An aqueous dispersion of 0.07 mol% copolymer with a particle diameter of 1600 Å and a solid content of 50% (component B) and a vinyl chloride copolymer aqueous dispersion with a particle diameter of 1400 Å and a solid content of 48.8% (manufactured by Sumitomo Chemical, Sumielite #) 1100) (component C) and a 3% aqueous solution of xanthan gum (trade name: Kelzan, Kelco, USA) (component D) in water with varying weight ratios to prepare a suspended high-frequency adhesive. This suspended high frequency adhesive has a density of 19g/10
75 mm thick polyurethane foam sheet
A polyurethane foam sheet having high-frequency adhesive properties was prepared by impregnating and coating the sample in an amount equal to % by weight and heating and drying it in a hot air dryer at 120° C. for 5 minutes. This high-frequency adhesive polyurethane foam sheet and a 3 mm thick hardboard (manufactured by Nippon Hardboard) were high-frequency bonded under the conditions shown in the text, and the adhesive strength was measured. Table 1 shows the blending ratio, texture, and adhesive strength of the components (A), (B), (C), and (D) above. As can be seen from the table, it is a suspended high-frequency adhesive that can give polyurethane foam sheets practical properties that are superior to the strength of the original polyurethane foam sheet (2.0 kg/25 mm width). .

[Table] Example 2 Component C used in Example 1 was freeze-dried into powder, blended with component A, and dispersed in component B to prepare a suspended high-frequency adhesive. Table 2 shows the results of the same evaluation as in Example 1 by changing the blending ratio. As is clear from the table, the adhesive strength showed almost the same value as in Example 1, indicating that it is practical.

[Table] Example 3 Vinylidene chloride 87 mol%, acrylonitrile 13
mol%, itaconic acid 0.05 mol% vinylidene chloride copolymer, the copolymer terminal has a functional group component formed from the decomposition product of a sodium persulfate initiator, and the particle size is JIS standard sieve 20 mesh pass;
A 200 mesh powder high frequency adhesive was dispersed in water to a concentration of 70 wt% to form a slurry high frequency adhesive. This slurry high-frequency adhesive was applied to a 3mm thick aluminum plate at a coating amount of 100g/ ^m2 .
Water was evaporated in a hot air dryer at 160°C for 1 minute to fix the high-frequency adhesive to the surface of the aluminum plate.
A 3 mm thick aluminum plate was superimposed on the adhesive side, and a pressure of 6 kg/cm ² G was applied to the electrode area of 5 mm x 4 mm using a 3 kW high-frequency adhesive machine (manufactured by Pearl Industries).
Second high frequency bonding. Example 4 The same powder as in Example 1 was dispersed at 30% by weight in an aqueous melamine resin solution (Resin PM-5 Showa Kobunshi) with a solid content of 51% to prepare a high-frequency adhesive in the form of a slurry.
Apply the adhesive at 100 g/m ² on a 2.5 mm thick cypress board.
After applying it to the amount of 3kw and air drying for 5 hours, overlap another cypress board with the adhesive side.
Electrode area 10mm using high frequency adhesive machine (Pearl Industries)
A pressure of 1.5 Kg/cm ² G was applied to 4 mm x 4 mm and high frequency bonding was performed for 30 seconds. For comparison, melamine resin alone was used at 150g/m ²
The adhesive strength of the applied product was measured and was 35Kg/cm ²
Therefore, it was not practical for plywood. Example 5 Same composition as Example 1, solid content 50%, particle size 1500
The same powder as in Example 1 was added to a water-dispersed latex of
It was dispersed at 30% by weight to form a slurry-like high-frequency adhesive. Coating amount 100g/ ^m2 on 2.5mm thick cypress board surface
After applying and drying at 100℃ for 2 minutes,
Example 4: Overlapping another cypress board with adhesive side
High frequency bonding was performed under the same conditions as . The shear adhesive strength is shown in Table 3.

[Table] Example 6 Powder of a copolymer of 87 mol% vinyl chloride and 13 mol% vinyl acetate with a particle size of 32 mesh pass JIS sieve and 170 mesh was mixed with 60 mol% vinylidene chloride, 40 mol% vinyl chloride, and 0.14 mol% acrylic acid. A high-frequency adhesive in the form of a slurry was dispersed in a water-dispersed latex with a solid content of 50% and a particle size of 1400 Å, consisting of mol%.
3mm thick paperboard (made by Japanese hardboard)
100g/m ² was applied to the surface and dried at 100°C for 2 minutes. Another paper board was superimposed on the adhesive layer and high-frequency bonding was performed under the same conditions as in Example 4. When the shear adhesive strength was measured, failure of the paperboard surface layer occurred. Comparative Example 1 Vinylidene fluoride 75 mol% by suspension polymerization,
A slurry dispersion of a terpolymer having a composition of 10 mol% of tetrachloroethylene and 15 mol% of hexafluoropropylene was obtained. Using this slurry dispersion, high frequency bonding of paperboard was attempted in the same manner as in Example 6. After applying pressure and high frequency,
It peeled off easily by hand, making it impossible to measure the adhesive strength. The industrial advantages of the present invention are summarized above. A high-frequency slurry adhesive with a high solid content that easily wets metals, glass, wood, fibrous materials, etc. It is dry during bonding and has practical adhesive strength. Easy to store and handle, and can be coated in thick coats. Excess slurry after coating and impregnation can be recycled and used without loss. The bonding process is easy to automate and can be easily installed in-line. High-frequency adhesive strength can be controlled by applying high-frequency voltage, contact temperature, and contact pressure.

Claims (1)

[Claims] 1. Vinylidene chloride component A of 20 mol % or more and 93 mol % or less and monomer B of 7 mol % or more and 80 mol % or less of one or more monomers copolymerizable with component A. and 0 mol% selected from functional monomers copolymerizable with component A and/or component B.
The above is a vinylidene chloride copolymer consisting of 10 mol% or less of monomer component C, the substantial particle diameter range of the polymer terminal is 0.5 μm or more and 1 mm or less, and 5% by weight or more of the powder, 80% by weight or less is 20
A high-frequency adhesive in the form of a slurry suspended in a dispersion medium of at least 95% by weight. 2. The slurry-like high-frequency adhesive according to claim 1, wherein the dispersion medium is water or an aqueous latex of a thermoplastic resin. 3. The slurry-like high-frequency adhesive according to claim 1, wherein the dispersion medium is an aqueous solution of a thermosetting resin and/or an aqueous latex.