JPH0242397B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention enables spray coating of a specific hydrosol composition having pressure-sensitive adhesive properties.
This invention relates to a novel solvent-free, water-dispersed aerosol type pressure-sensitive adhesive composition that has significantly improved various properties such as workability, stain resistance, initial adhesion, and water resistance. [Prior Art] Conventionally, pressure sensitive adhesives have been used either by being applied directly to the adhesive surface, or as pressure sensitive adhesive tapes being applied to one or both sides of a support such as paper or plastic film. In the former case, there are problems in terms of application over a wide area and in terms of workability, and in the latter case, it is difficult to use it particularly on rough surfaces, and its uses are limited. As a way to solve these problems, spray application of pressure-sensitive adhesives has the advantage of being easy to work with and can be applied uniformly to rough surfaces, so it can be used not only for industrial purposes but also for general household use. There are also many. As an aerosol type pressure sensitive adhesive, Tokko Sho
As seen in Japanese Patent No. 46-12460, a solvent type using an organic solvent as a medium is used. However, although these solvent-based aerosol pressure-sensitive adhesives are good in terms of sprayability and various adhesive properties, they are relatively low in concentration to prevent stringing during spraying, so they cannot be used in large quantities. Since organic solvents are inevitably used, they pose flammability during use, inhalation toxicity to humans, and other pollution-related problems, so it was necessary to pay close attention when using them. Spray versions of emulsion-type pressure-sensitive adhesives have been developed to improve the above-mentioned problems, but while they are non-polluting, they are not used as air sprays or airless sprays due to the stability of the emulsion particles. However, from the viewpoint of portability, it could not be used as an aerosol spray, which is the simplest and most requested. In other words, when an emulsion-type pressure-sensitive adhesive is sealed in a pressure can with a propellant such as liquefied petroleum gas (LPG), chlorofluorocarbon gas, or ethers, the emulsion particles swell, coagulate, and gel due to the propellant during storage. , causing phenomena such as thickening and becoming unstable. Furthermore, when spraying, the emulsion particles are destroyed by the large mechanical shearing force at the nozzle, resulting in clogging of the nozzle, resulting in poor spray performance, and the interface used in the production of pressure-sensitive adhesives. At present, solvent-free aerosol pressure-sensitive adhesives have not yet been put into practical use, as there are problems such as the unavoidable foaming during spraying caused by the activator, which prevents uniform application. [Problems to be solved by the invention] As described above, conventional aerosol-type pressure-sensitive adhesives have problems such as toxicity and pollution when they are solvent-based, while emulsion-type pressure-sensitive adhesives do not have these problems. However, on the other hand, there was a problem that it was difficult to perform a stable aerosol spray due to destabilization of the emulsion particles and foaming during spraying. Therefore, the present invention solves the above-mentioned conventional problems and makes it possible to perform a stable aerosol spray without a solvent, and also to form an adhesive coating film with good adhesive properties using this aerosol spray. The object of the present invention is to provide an industrially useful aerosol type pressure-sensitive adhesive composition. [Means for Solving the Problems] As a result of intensive studies to achieve the above object, the inventors found that the particle size of the dispersed particles is smaller and more stable than that of the conventional emulsion type adhesive. By using a hydrosol-type adhesive with a high level of hydration, and using a water-soluble polymer substance as one of the components of this adhesive, which greatly contributes to the stability of the hydrosol, it is possible to produce a stable aerosol spray over a long period of time. In addition, by this aerosol spray, a solvent-free, water-dispersed aerosol-type pressure-sensitive adhesive composition that can form an adhesive coating film with excellent adhesive properties such as initial adhesive strength and cohesive force can be obtained. Knowing this, he completed this invention. That is, this invention mainly consists of 1 to 20% by weight of an unsaturated monomer having an acidic group and a (meth)acrylic acid alkyl ester having an alkyl group having 2 to 15 carbon atoms that can be copolymerized with the unsaturated monomer. Other unsaturated monomers
^Weight average molecular weight consisting of 99-80% by weight ^104-106
A water-dispersed hydrosol with an average particle diameter of 0.01 to 0.1 μm obtained by adding an alkali and water to the copolymer to neutralize some or all of the acidic groups in the copolymer and inverting the phase. Provided is an aerosol-type pressure-sensitive adhesive composition comprising as essential components a water-soluble polymeric substance in a proportion of 0.01 to 20 parts by weight based on 100 parts by weight of the above-mentioned copolymer contained in the hydrosol, and further a propellant. It is something to do. [Structure and operation of the invention] The unsaturated monomer having an acidic group used to obtain the copolymer in this invention is used to introduce a functional group, that is, an acidic group, necessary for hydrosolization into the copolymer. For example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fyalic acid, styrene sulfonic acid, allylsulfonic acid sulfopropyl acrylate, and 2-acryloyloxynaphthalene-2- Sulfonic acid, 2-methacryloyloxynaphthalene-2-sulfonic acid, 2-
Examples include unsaturated sulfonic acids such as acrylamide-2-methylpropanesulfonic acid and 2-acryloyloxybenzenesulfonic acid, and one or more of these monomers can be used. The amount of the unsaturated monomer having an acidic group is as follows:
1 to 20% by weight, preferably 3 to 10% by weight in the monomer mixture to obtain the copolymer. If the amount of this monomer used is less than 1% by weight, it will be difficult to form a hydrosol, and if it is used in excess of 20% by weight, there is a risk that adhesive properties such as tackiness and adhesiveness will be affected. be. On the other hand, other unsaturated monomers that can be copolymerized with the above monomers are important components for imparting pressure-sensitive adhesive properties, such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic acid Alkyl groups with 2 to 15 carbon atoms (meth) such as isooctyl, ethyl methacrylate, butyl methacrylate, etc.
Acrylic acid alkyl ester is used as the main component. This main monomer may be used alone or in combination of two or more types. Further, up to 40% by weight of this main monomer may be replaced with other modifying monomers. Modifying monomers include (meth)acrylic acid alkyl esters in which the number of carbon atoms in the alkyl group is outside the above range, such as methyl acrylate and methyl methacrylate, vinyl acetate, acrylonitrile, styrene, and 2-methoxyethyl acrylate. ,
Examples include vinyl ethers, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, acrylamide, N-methylolacrylamide, and the like. The amount of the main monomer or the copolymerizable unsaturated monomer composed of the main monomer and the modifying monomer should be determined based on the total monomer mixture to obtain the copolymer.
80-99% by weight, preferably 90-97% by weight. A mixture of these monomers can be copolymerized by conventionally known methods such as solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization. This is a solution polymerization method using a solvent. Among these polymerization methods, in the bulk polymerization method, the copolymer obtained by this polymerization method can be used as it is as a raw material for hydrosolization.
In the solution polymerization method, if the amount of solvent used is more than 20% by weight, part or all of the organic solvent is removed after polymerization by means such as distillation, but if it is less than 20% by weight, it is converted into a hydrosol as it is. It can be used as a raw material. The organic solvent in this case is preferably an alcoholic water-soluble solvent as described below. Of course, even if it is less than 20% by weight, part or all of it can be removed by the same means as described above. Note that various general organic solvents can be used as the solvent used in the solution polymerization method, but if the solvent is to be subjected to hydrosolization with some or all remaining after polymerization, preferably methyl alcohol, ethyl alcohol, n- butyl alcohol,
It is desirable to use an alcohol-based hydrophilic solvent such as n-propyl alcohol, isopropyl alcohol, or sec-butyl alcohol, or an oligomer or prepolymer having a hydrophilic group such as a hydroxyl group, a carboxyl group, or an amino group. On the other hand, in other polymerization methods, the medium used in each method is removed by appropriate means after synthesis to obtain a solid material practically free of medium. That is, in the emulsion polymerization method, water is removed by coagulating and separating by salting out, and in the suspension polymerization method, water is removed by filtering the particulate copolymer. In addition,
Some of the emulsifier or dispersant used during polymerization will adhere to the surface of the copolymer particles, but this will be removed during the above-mentioned medium removal operation, and if necessary, it will be almost completely removed by washing several times. Just remove it. In addition, in the emulsion polymerization method, highly three-dimensional copolymers, so-called gelled products, may be produced, but such copolymers can be an obstacle to hydrosolization, and are It is desirable to prevent the formation of this copolymer as much as possible during heating.
However, even if a small amount of this type of copolymer is produced, it can be solved by masticating using a mixing roll, a Banbury mixer, etc., and applying a high shearing force. The weight average molecular weight of the copolymer thus obtained must be designed within the range of 10 ⁴ to 10 ⁶ , and if this molecular weight is less than 10 ⁴ , the cohesive strength of the pressure-sensitive adhesive of this invention will decrease. Because of the scarcity of
Even if the adhesive is sprayed onto the object to be coated and then adhered, sufficient adhesive strength may not be obtained and the adhesive may fall off, which is not preferable. Furthermore, if the molecular weight exceeds 10 ⁶ , it becomes difficult to form a hydrosol, which may lead to unfavorable results in terms of adhesive properties and the like. In this invention, while stirring the copolymer thus obtained, alkali and water are added to neutralize some or all of the acidic groups in the copolymer and convert it into an O/W type. The phases are combined to prepare a water-dispersed hydrosol. At this time, in order to facilitate hydrosolization, the total amount of the organic solvent that may be contained in this copolymer is 20 parts by weight or less based on 100 parts by weight of the copolymer, if necessary. Proportion of methyl alcohol, ethyl alcohol, n-
propyl alcohol, isopropyl alcohol,
After adding an alcohol-based water-soluble solvent such as sec-butyl alcohol, an alkali and water may be added for phase inversion. Examples of the alkali used here include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, amines such as ethylamine and propylamine, ammonia, and α-aminoethyl alcohol. Among these, those that can be easily scattered when sprayed, such as ammonia, are preferred, and can prevent deterioration of adhesive properties due to residual non-volatile alkali. The amount of the alkali to be used may be 0.02 to 2 equivalents relative to the acidic groups in the copolymer in order to neutralize some or all of the acidic groups in the copolymer. The temperature during the neutralization treatment can be appropriately set depending on the type and properties of the copolymer, but is generally preferably in the range of 30 to 95°C. An example of the method for neutralization treatment and hydrosolization is to add a predetermined amount of alkali or alkaline aqueous solution to the previously polymerized and separated copolymer, stir and mix well, and then gradually add water to perform phase inversion. There is a method of forming an O/W type dispersion in which copolymer particles are finely dispersed by using water as a continuous phase. Of course, the present invention is not limited to this at all, and an aqueous alkaline solution may be added instead of the water used during phase inversion to perform the neutralization treatment and hydrosolization at the same time. The water-dispersed hydrosol obtained in this way is
It is stably dispersed with an average particle size in the range of 0.01 to 0.1 μm, and the solid content concentration for good sprayability is 5 to 45% by weight. The water-soluble polymeric substance used in this invention imparts stability to the hydrosol during aerosolization, and is preferably a synthetic polymeric substance or a semi-synthetic polymeric substance. Of course, this does not preclude the use of natural polymeric substances such as starch. Examples of the above synthetic polymer substances include polyvinyl alcohol, sodium polyacrylate, and polyvinylpyrrolidone, and in addition, nonionic water-soluble polymer substances having alkylene oxide groups such as ethylene oxide and propylene oxide, and water-soluble polyurethane resins. etc. are included. The above nonionic water-soluble polymer substances include:
General formula R—O(—CmH ₂ mO)— _o H or R—O(—
CmH ₂ mO) - _o Mono- or dialkyl ethers of polyalkylene glycol represented by R, such as polyethylene glycol mono(or di)alkyl ethers, polypropylene glycol mono(or di)alkyl ethers, or R
―COO(―CmH ₂ mO)― _o H or R―COO(―
CmH ₂ mO)― _o Mono or Di expressed in OCR
Alkyl esters, such as polyethylene glycol mono(or di)laurate, polyethylene glycol mono(or di)stearate, polypropylene glycol mono(or di)laurate, polypropylene glycol mono(or di)stearate, and the like. In addition, as the above water-soluble polyurethane resin, for example, the general formula [(-CmH ₂ mO)- _o CONH-R
―NHCOO〕― Those made from a water-soluble polyol represented by _l or the following general formula; Examples include cationic water-based urethane resins represented by the following, and various water-soluble polyurethane resins can be used depending on the raw material polyol. Furthermore, examples of the semi-synthetic polymeric substances include cellulose-based substances such as carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, and methyl cellulose, and starch-based substances such as soluble starch and carboxymethyl starch. Among these water-soluble polymer substances, those that are unlikely to cause a decrease in tackiness and water resistance as pressure-sensitive adhesives and have relatively little thickening effect are preferred, and from this point of view, the nonionic water-soluble Polymeric substances or water-soluble polyurethane resins are particularly preferred. In addition, if the molecular weight is too low, it will significantly impede the water resistance of the resulting coating film, and if it is too high, the water solubility will decrease. A range of 10,000 is preferred. The use of these water-soluble polymer substances is not limited to one type, and two or more types may be used in combination. As for the method of adding it, either a method of adding it to the copolymer before hydrosolization or a method of adding and mixing it to the generated hydrosol is possible. Further, when adding, it is preferable to dissolve the above-mentioned polymeric substance in a small amount of water in advance and then add it. The amount of the water-soluble polymer substance used varies depending on the composition of the copolymer constituting the hydrosol and the stability of the hydrosol particles.
0.01 to 20 parts by weight, especially 0.05 to 100 parts by weight
Preferably, the amount is 15 parts by weight. The above usage amount is 0.01
If it is less than 20 parts by weight, the stability of the hydrosol particles in the aerosol can will be poor, and if it is used in excess of 20 parts by weight, the viscosity of the system (of the hydrosol) will become too high, which will cause the hydrosol particles to become unstable in the aerosol can. There is a risk that the particles within the adhesive may become unstable or stringy, and adhesive properties such as tackiness and adhesion, particularly water resistance, may deteriorate. If necessary, an external crosslinking agent may be added to the hydrosol composition thus obtained to improve adhesive properties. This crosslinking agent can be added at any stage before or after synthesis of the copolymer. In addition, various additives such as ordinary tackifiers, softeners, plasticizers, fillers, film-forming aids, colorants, fragrances, fluorescent agents, anti-aging agents, rust preventives, antibacterial agents, alcohols, and cellosolves are added. A small amount of a hydrophilic solvent such as the following may be added at any manufacturing step, including the step of incorporating the propellant described below. The aerosol-type pressure-sensitive adhesive composition of the present invention is filled into a sealed pressure-resistant container for aerosol, containing the hydrosol, the water-soluble polymer substance, and a propellant as essential components. As the propellant to be used, any propellant that is normally used as a propellant for aerosols, such as LPG, chlorofluorocarbon gas, and dimethyl ether, can be used. Freon gas and dimethyl ether are preferred from the viewpoint of sprayability. The blending ratio of this propellant and the hydrosol composition (solid content concentration 5 to 45% by weight) is usually 30 to 90% by weight/10 to 70% by weight, depending on the purpose of use and the type of monomer used. It can be selected as appropriate. If the blending ratio of the propellant exceeds the above range, a large amount of spraying will be required to obtain the desired adhesiveness. In addition, if the blending ratio is small, the viscosity of the system increases, making it impossible to spray uniformly and resulting in a failure to obtain a uniform coating film. [Effects of the Invention] As described above, the aerosol type pressure-sensitive adhesive composition of the present invention is a water-dispersed hydrosol obtained by adding an alkali and water to a specific copolymer having an acidic group to neutralize it and invert its phase. Moreover, since we use a very stable ultra-fine particulate hydrosol composition containing a water-soluble polymeric substance as an essential ingredient in combination with a propellant, we can achieve It has excellent storage stability and sprayability, and can solve the problems of pollution that are the drawbacks of solvent-based products. That is, when the composition of this invention is sprayed, it does not foam because it does not contain a surfactant, the particle size is very fine at about 0.01 to 0.1 μm, and the particles are stabilized by the water-soluble polymer. As a result, it has excellent storage stability and a uniform adhesive coating with good sprayability.This coating has excellent initial adhesive strength due to its early drying properties, which are proportional to the fine particle size. Demonstrates excellent performance. That is, according to the present invention, it is possible to provide an aerosol-type pressure-sensitive adhesive composition that is solvent-free but has sprayability comparable to solvent-based adhesives, excellent storage stability, and adhesive properties. [Examples] Examples of the present invention will be shown below and will be explained in more detail. However, the present invention is not limited only to these examples, and various modifications may be made without departing from the technical idea of the present invention. can be applied. In addition, parts in the following examples and comparative examples mean parts by weight. Example 1 90 parts of n-butyl acrylate, ethyl acrylate
10 parts, acrylic acid 9 parts, benzoyl peroxide
10% by weight of a mixture consisting of 0.1 part of lauryl mercaptan and 0.05 part of lauryl mercaptan was charged into a four-necked flask, and the flask was purged with nitrogen for about 40 minutes while stirring. Then, the inner bath temperature is raised to start the polymerization reaction,
The reaction temperature was controlled at 83°C ± 5°C by controlling the stirring speed, the external bath temperature, and the dropping rate of the remaining mixture, and the reaction was allowed to proceed for 4 hours while adding the remaining mixture dropwise ^. A copolymer was obtained. To 100 parts of this copolymer, 5 parts of a 25% by weight aqueous solution of a nonionic water-soluble polymer substance (product name: Unisafe UI1300, manufactured by NOF Corporation) was added and mixed.
Neutralization was performed by adding 0.4 equivalents of aqueous ammonia (10% by weight) to the carboxyl groups of the copolymer, and water was further added to cause phase inversion to obtain a hydrosol in which the continuous phase was water. The obtained hydrosol has a solid content concentration of 30.2% by weight, a viscosity of 24 poise at 25°C, and an average particle size (according to Nanosizer) of 0.05μ.
It was m. Hydrosol composition thus obtained 100
A mixture of 1.5 parts of methylcellosolve and 0.5 parts of fragrance was mixed in a ratio of 60% by weight and 40% by weight of dimethyl ether, and the mixture was filled into an aerosol can to obtain an aerosol-type pressure-sensitive adhesive composition of the present invention. . Example 2 10 of a monomer mixture consisting of 80 parts of 2-ethylhexyl acrylate, 15 parts of n-butyl acrylate, 5 parts of acrylonitrile, and 8 parts of methacrylic acid
% by weight and 5 parts of n-propyl alcohol were placed in a four-necked flask, and the flask was purged with nitrogen for about 40 minutes while stirring. Then, benzoyl peroxide
After 0.1 part was added and completely dissolved, the temperature was raised to 80°C to start polymerization. The polymerization reaction was carried out by controlling the reaction temperature at 83°C ± 5°C by adjusting the stirring speed, external bath temperature, and dropping speed while dropping the remaining monomer mixture, and reacting for 4 hours to achieve a weight average molecular weight of 4 × 10 ⁵ (by GPC)
A copolymer was obtained. Next, an ammonia aqueous solution (10% concentration by weight) of 0.8 equivalent to the carboxyl group of the above copolymer.
and water were added to perform neutralization and phase inversion at a temperature of 70°C to obtain a hydrosol in which the continuous phase was water. The obtained hydrosol had a solid content concentration of 33% by weight, a viscosity at 25° C. of 72 poise, and an average particle size (measured by Nanosizer) of 0.06 μm. To 100 parts of this hydrosol, 0.5% of a 25% by weight aqueous solution of a water-soluble polyurethane resin (trade name: Coraclar PU-85, manufactured by BASF) was added as a water-soluble polymer substance.
part was added and mixed. 35 parts of dichlorodifluoromethane (Freon 12) was mixed with 65 parts of the hydrosol composition thus obtained, and the mixture was filled into an aerosol can to obtain an aerosol-type pressure-sensitive adhesive composition of the present invention. Example 3 A mixture of 90 parts of n-butyl acrylate, 10 parts of 2-methoxyethyl acrylate, 5 parts of acrylic acid, 0.15 parts of lauryl mercaptan, 3 parts of polyoxyethylene alkyl phenol ether, and 160 parts of water was poured into four mouths. Pour into a flask and stir while stirring.
Heated to 70°C, added 5 parts of potassium persulfate aqueous solution (2% concentration by weight) to initiate polymerization, and carried out emulsion polymerization for 3 hours while maintaining the reaction temperature at about 70°C, resulting in a weight average molecular weight of 5x. A copolymer emulsion of 10 ⁵ (according to GPC) was obtained. Next, the obtained copolymer emulsion is salted out by a conventional method, the precipitated copolymer is filtered, washed with water, and dried, and 5 parts of isopropyl alcohol is added to 100 parts of this copolymer. After mixing, a hydrosol was obtained in the same manner as in Example 1. The obtained hydrosol had a solid content concentration of 32% by weight, a viscosity at 25° C. of 53 poise, and an average particle size (measured by Nanosizer) of 0.08 μm. To 100 parts of this hydrosol, add polyvinyl alcohol (trade name Gohsenol GH manufactured by Nippon Gosei Kagaku Co., Ltd.) to 100 parts of this hydrosol.
10 parts of a 4% by weight aqueous solution of 17; Saponification degree: 88%) were added and mixed. Using the hydrosol composition thus obtained, the same operations as in Example 1 were carried out to obtain an aerosol type pressure-sensitive adhesive composition of the present invention. Comparative Example: Without hydrosolizing the copolymer emulsion obtained in Example 3,
The viscosity was increased by adding 0.3 equivalents of ammonia aqueous solution (25% by weight) to obtain an emulsion type pressure sensitive adhesive. This emulsion has a solids concentration of 39.2
The viscosity at 25° C. was 90 poise, and the average particle diameter (according to Nanosizer) was 0.15 μm. The resulting emulsion type pressure sensitive adhesive
100 parts of methyl cellosolve in the same manner as in Example 1.
A mixture of 1.5 parts and 0.5 parts of fragrance is mixed in a proportion of 60% by weight and 40% by weight of dimethyl ether,
An emulsion type aerosol type pressure sensitive adhesive composition was obtained by filling an aerosol can. Using the aerosol-type pressure-sensitive adhesive composition obtained in each example, spray it uniformly onto each target material shown in Table 1 at a coating amount of 50 g/ ^m2 , and after 5 seconds apply it to the target material. After combining them and pressing them back and forth once with a 1 kg roller, they were left to stand for a predetermined period of time. After standing, the material to be coated was peeled off in a direction of 180 degrees to the surface to which it was applied, and the adhesive strength was measured. The measurement results are shown in Table 1. Furthermore, when the emulsion-type aerosol-type pressure-sensitive adhesive composition obtained in the comparative example was sprayed, sagging and agglomerates were generated at the spout, resulting in very poor sprayability, making it difficult to obtain a uniform coating film. I couldn't help it. Foaming was also observed on the coated surface. Furthermore, the contents agglomerated one week after storage, making spraying completely impossible. In addition, each aerosol type pressure-sensitive adhesive composition was uniformly applied on a glass plate at 50 g/m ² and 50 g/m 2 was applied at 100°C.
It was dried for a minute to form a coating. This was immersed in ion-exchanged water at 40°C, and changes in the coating film were monitored. The results are shown in Table 2.

【table】

【table】

[Table] Natatsuta As is clear from Tables 1 and 2, when the aerosol type pressure-sensitive adhesive composition of the present invention is sprayed, initial adhesion develops very quickly, good adhesive strength is obtained, and Excellent water resistance,
Furthermore, due to the good sprayability, no foaming, no agglomerates, and no sag were observed at the spout. Furthermore, the contents did not aggregate even after being stored at 40°C for 6 months, demonstrating excellent storage stability.

Claims (1)

[Claims] 1 1 to 20% by weight of unsaturated monomers having acidic groups
and the carbon number of the alkyl group that can be copolymerized with this is 2
An alkali and water are added to a copolymer with a weight average molecular weight of ¹⁰⁴ to ¹⁰⁶ , which is composed of 99 to 80% by weight of an unsaturated monomer mainly composed of ~15 (meth)acrylic acid alkyl esters. A water-dispersed hydrosol with an average particle diameter of 0.01 to 0.1 μm obtained by neutralizing some or all of the acidic groups in the polymer and inverting the phase, and 100 parts by weight of the above copolymer contained in this hydrosol. An aerosol-type pressure-sensitive adhesive composition comprising as essential components a water-soluble polymer material in a proportion of 0.01 to 20 parts by weight, and a propellant.