JPH0157710B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a pressure-sensitive adhesive material, and more particularly to a method for producing a polyurethane-based pressure-sensitive adhesive material having excellent adhesion to various adherends in a shortened process. Conventionally, the manufacturing method of pressure-sensitive adhesive materials used for purposes such as adhesion, packaging, insulation, anti-corrosion, and vibration damping is as follows: (1) A rubber-based or acrylic-based polymer material is added with a tackifier resin, a softener, and a plasticizer. A solvent-based adhesive composition is prepared by dissolving a mixture of agents, etc. in an organic solvent, making a solution with a solid content of about 30%, and coating it on a support such as a plastic sheet, and then volatilizing the solvent in a subsequent heating and drying process. There is a method in which an adhesive layer is formed on a support, and then a release paper is layered and rolled up. However, the solvent used in this method does not contribute in any way to its function as an adhesive, and it must be used in large amounts relative to the solid content. There are drawbacks such as the need for additional equipment. In order to improve these drawbacks, (2) a method using a polyurethane-based, ie, solvent-free adhesive composition containing a tackifying resin has been proposed. However, this manufacturing method requires a step of applying the adhesive composition onto the support and passing it through a heating curing oven for the curing reaction of the adhesive layer. Moreover, in this process, rolls cannot be used because the adhesive layer is sticky, and long straight equipment is inevitably required, resulting in high equipment costs and a large floor space. It has drawbacks such as: In addition, in order to solve this problem, it is possible to manufacture it through a process using a roll by overlapping release paper on the adhesive layer when it is not cured, but the adhesion to the release paper and the thickness of the adhesive layer may be difficult. If the adhesive layer is too thick, there are major drawbacks such as the release paper folding when it passes through the rolls, wrinkles appearing on the surface of the adhesive layer, and quality deterioration. Furthermore, the adhesive strength of polyurethane-based adhesive materials obtained by conventional methods is not necessarily sufficient, and the fields of their use are also limited. As a result of intensive research to solve various problems of these conventional techniques, the present inventors have discovered that in the production of pressure-sensitive adhesive materials, an active hydrogen group-containing compound is reacted with a polyisocyanate compound in the coexistence of a tackifier. discovered that it is possible to prevent adhesive adhesion to the roll by treating the surface of the adhesive layer with water before the curing reaction is completed. Moreover,
It has been found that this treatment of water not only does not have any adverse effect on the adhesive strength of the pressure-sensitive adhesive material, but also significantly improves the adhesive strength. The present invention
It was completed based on these findings. That is, the present invention provides a pressure-sensitive adhesive for forming an adhesive layer on a support, comprising an adhesive composition comprising (A) a liquid rubber containing active hydrogen groups, (B) a tackifying substance, and (C) a polyisocyanate compound. A method for producing a pressure-sensitive adhesive material, characterized in that in producing the material, the surface of the adhesive layer coated on the support is treated with water for 0.5 to 2 hours 1 to 20 minutes after adding the polyisocyanate compound. It provides: The method for producing a pressure-sensitive adhesive material of the present invention employs a step of treating the surface of the adhesive layer with water, thereby preventing the adhesive layer from adhering to the roll when it is not yet cured. This makes it possible to use extremely shortened curing equipment using rolls compared to manufacturing methods that use linear heat curing equipment. The adhesive composition used in the method for producing a pressure-sensitive adhesive material of the present invention comprises (A) a liquid rubber containing active hydrogen groups, (B) a tackifying substance, and (C) a polyisocyanate compound. Here, the active hydrogen group-containing liquid rubber (A) includes a liquid rubber having an active hydrogen group such as a hydroxyl group, an amino group, an imino group, a carboxyl group, or a mercapto group at the molecular end. These liquid rubbers have a number average molecular weight of 500
~25,000 diene polymers and copolymers with 4 to 12 carbon atoms, as well as these diene monomers and 2 to 22 carbon atoms.
There are copolymers with α-olefinic addition polymerizable monomers. Specifically, there are polybutadiene homopolymer, polyisoprene homopolymer, butadiene-isoprene copolymer, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate copolymer, and the like. Among these, those with a viscosity of 2000 poise or less at room temperature are preferred, and those with a viscosity of 500 poise or less are more preferred.
Further, as for its fine structure, a liquid rubber having 50% or more of 1,4 bonds is preferably used. Liquid rubbers having active hydrogen groups are excellent in terms of compatibility with tackifying substances described below, a wide blendable range, and water resistance. Next, the tackifying substance (B) used in the present invention includes bituminous substances and tackifying resins. There is no particular restriction on the bituminous material, and straight asphalt, semi-brown asphalt, blown asphalt, or a mixture thereof can be exemplified. Next, as tackifying resins, alkyl phenol resins, terpene resins, terpene phenol resins, xylene formaldehyde resins, rosin,
Examples include hydrogenated rosin, coumaron resin, aliphatic and aromatic petroleum resins, and the like. As these tackifying substances, those having a softening point of about 40 to 150°C are used. The amount of the tackifier can be freely selected depending on the intended use of the pressure-sensitive adhesive material to be produced, the thickness of the adhesive layer, etc. Usually, the amount is in the range of 10 to 1000 parts by weight, preferably 20 to 600 parts by weight, based on 100 parts by weight of the active hydrogen group-containing liquid rubber (A).
The amount of compounding also varies depending on the type of liquid rubber containing active hydrogen groups, but no matter which liquid rubber is used, it is possible to increase the amount of compounding, and as a result, the cost of the adhesive is extremely low. become. Therefore, by increasing the thickness of the adhesive layer, it can be used not only as a pressure-sensitive adhesive but also as a damping material with adhesive properties, for example. Next, the polyisocyanate compound (C) used in the present invention is an organic compound having two or more isocyanate groups in one molecule, and is reactive with the active hydrogen group of the active hydrogen group-containing liquid rubber. It has an isocyanate group. Such polyisocyanate compounds are well known and may be in the form of prepolymers having terminal isocyanate groups obtained by reacting a polyol and a polyisocyanate in advance.
Examples of polyisocyanate compounds include the usual aromatic, aliphatic and cycloaliphatic ones, such as tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, liquid modified diphenylmethane diisocyanate, polymethylene Polyphenyl isocyanate, xylylene diisocyanate, cyclohexyl diisocyanate, cyclohexanephenylene diisocyanate, naphthalene-1,
5-diisocyanate, isopropylbenzene-
Examples include 2,4-diisocyanate, polypropylene glycol and tolylene diisocyanate addition reaction products. These polyisocyanate compounds act as a curing or crosslinking component of the active hydrogen group-containing liquid rubber, and the amount of the polyisocyanate compound is usually determined so that the isocyanate group is relative to the active hydrogen group of the active hydrogen group-containing liquid rubber.
What is necessary is just to determine so that it may become 0.3-0.98 equivalent, more preferably 0.4-0.95 equivalent. If this amount is too small (less than 0.3), the adhesive strength will be too low to be practical, and the heat resistance and cold resistance will also be poor. Also,
If it is added in excess of more than 0.98, the heat resistance and cold resistance will be good, but the adhesive strength will be significantly reduced, which is not preferable. As detailed above, the adhesive composition used in the present invention essentially contains three components (A), (B), and (C), but other auxiliary agents may be added as necessary. It is not a restriction. The method of addition is not particularly limited either, but it is advantageous to add it before adding the polyisocyanate compound and thoroughly mix it. The auxiliary agents used include (1) urethane catalysts such as di-t-butyltin dilaurate, stannath octoate, triethylenediamine, diethylenediamine, triethylamine, naphthenic acid metal salts, and octylic acid metal salts; (2) dioctyl phthalate;
Viscosity modifiers such as process oil, (3) Fillers such as carbon black, calcium carbonate, clay, talc, mica, and various fiber materials, (4) Stabilizers such as anti-aging agents, antioxidants, and ultraviolet absorbers. (Five)
These include foaming agents and (6) coloring agents. Next, a method for manufacturing the pressure-sensitive adhesive material of the present invention will be explained. First, (A) active hydrogen group-containing liquid rubber, (B) tackifying substance, and any necessary auxiliary agents are added and mixed uniformly using a Banbury mixer, kneader, etc. Next, a polyisocyanate compound is added and mixed thoroughly. do. When there is a large amount of mixture to be mixed, it is preferable to use a multi-component continuous mixer. Next, this mixture is coated and cast onto a support as it is or via an undercoat layer using a reverse coater, kiss coater, knife coater, extruder, etc. to form an adhesive layer. The support is arbitrarily selected from textiles, paper, metals such as aluminum, films or sheets of cellophane, polyester, polyamide, polyvinyl chloride, polyethylene, polypropylene, etc. depending on the purpose of use. In addition, the thickness of the adhesive layer formed on the support is usually 20μ or more, and can be used in a wide range of applications, from adhesive tapes and adhesive foils to other functional applications such as anticorrosion sheets and vibration damping sheets. It can be manufactured up to a range of several millimeters. The support on which the adhesive layer has been formed in this way is
The adhesive layer is introduced into a heating furnace and undergoes a curing reaction under conditions of 40 to 100°C, converting it into a pressure-sensitive adhesive layer that does not flow, string, or transfer to the release paper.
The feature of the present invention is that the surface of the adhesive layer is treated with water before the curing reaction of the adhesive layer is completed. Specifically, the surface of the adhesive layer coated on the support is treated with the polyisocyanate compound. After 1 to 20 minutes, treat with water for 0.5 to 2 hours. Treatment methods using water include immersion in water or hot water, spraying with water or steam, and a combination of these methods. This water treatment reduces the adhesion of the adhesive layer to the rolls before the curing reaction is complete, making it possible to create curved, shortened compacts using rolls, which previously could not be used in this curing process due to their tackiness. This made it possible to employ advanced equipment. The present inventors thought that it would be possible to some extent to reduce the adhesive force between the adhesive layer and the roll by allowing water to exist between the adhesive layer and the roll before the curing reaction is completed, but at the same time, It was estimated that the curing reaction would be completed and the adhesive strength would be drastically reduced, making it impossible to obtain a material that had the performance as a pressure-sensitive adhesive material. However, according to experiments conducted by the present inventors, surprisingly, not only was there no problem with adhesion to the roll, but the adhesion strength was also significantly improved compared to when no water was used. It was found that the effect of These facts were first discovered through research by the present inventors. After the curing reaction of the adhesive layer is completed, the pressure-sensitive adhesive material thus obtained is rolled up into a roll with a release paper layered thereon to form a product. As described in detail above, the method of the present invention makes it possible to carry out the curing reaction step of the adhesive layer using significantly reduced equipment compared to conventional manufacturing methods. Therefore, productivity is improved and manufacturing costs are greatly reduced. Furthermore, the thickness of the adhesive layer can be changed freely, providing a wide variety of products. Furthermore, it has become possible to provide an adhesive material with greatly improved adhesive performance. The pressure-sensitive adhesive material obtained by the method of the present invention leaves unreacted active hydrogen groups and has excellent self-adhesive properties when combined with a tackifier. In addition, by changing the type and amount of active hydrogen group-containing liquid rubber and tackifying substances, as well as the ratio of isocyanate groups to active hydrogen groups, we can create materials with adhesive strength levels that suit the intended use. It is possible to manufacture Therefore, the pressure-sensitive adhesive material obtained by the production method of the present invention can be used for adhesive tapes, insulating tapes, anticorrosion tapes, packing materials, vibration damping materials, and the like. Examples of the present invention are shown below. Examples and Comparative Examples Liquid polybutadiene with terminal hydroxyl groups (number average molecular weight 2800, viscosity 50 poise (30°C), hydroxyl group content 0.83meq/g, fine structure trans-1,4
60%, cis-1,4 20%, vinyl-1,2 20
%) 100 parts by weight, straight asphalt (60/
80) After thoroughly mixing 150 parts by weight and 0.05 parts by weight of di-n-butyltin dilaurate at 70°C, 7 parts by weight of polymethylene polyphenyl isocyanate (isocyanate content 30.6% by weight) (NCO/OH=
0.65) was added and stirred to obtain an adhesive composition. This adhesive composition is applied onto a cotton cloth and immersed in water immediately after adding polyisocyanate or 2 minutes, 15 minutes, or 90 minutes after addition, and after 60 minutes (however, if it is immersed immediately after adding polyisocyanate, After 17 hours), it was taken out and dried at 60°C for 1 hour to obtain a pressure-sensitive adhesive material. The curing time of this adhesive composition is approximately 13 at 65°C.
It's a minute. In this case, no adhesion to the metal roll was observed after immersion in water. The resulting pressure-sensitive adhesive material was placed on the adherend with the adhesive side facing down, and a 5 kg roll was run three times to apply a load, and the 180 degree peel strength was measured 24 hours later. The results are shown in the table.

[Table] *Material failure, others are interfacial failure

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Adhesive composition, 2... Support, 3... Release paper, 4... Pressure sensitive adhesive material, 5... Doctor knife, A... Curing reaction zone, B... Water treatment.

Claims (1)

[Scope of Claims] 1. A method for forming an adhesive layer on a support, comprising an adhesive composition comprising (A) a liquid rubber containing active hydrogen groups, (B) a tackifying substance, and (C) a polyisocyanate compound. In the production of a pressure sensitive adhesive material, the surface of the adhesive layer coated on a support is treated with water for 0.5 to 2 hours 1 to 20 minutes after adding the polyisocyanate compound. Production method. 2. The manufacturing method according to claim 1, wherein the tackifying substance is a bituminous substance and/or a tackifying resin. 3 The ratio of active hydrogen groups to isocyanate groups is 1:
The manufacturing method according to claim 1 or 2, wherein the equivalent ratio is 0.3 to 0.98 (equivalent ratio).