JP2733107B2 - Aqueous release agent - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an aqueous release agent mainly used for a pressure-sensitive adhesive tape or sheet based on paper or a plastic film.

In general, to protect the pressure-sensitive adhesive tape, sheet, etc., to protect the pressure-sensitive adhesive surface, paste a release paper on the pressure-sensitive adhesive-coated surface, or roll it in a roll and paste it on the back of the substrate on the pressure-sensitive adhesive-coated surface. That is being done. A release agent is applied to the surface of the release paper or the back surface of the substrate to improve the releasability during use.

[Prior art] Conventionally, solvent-type release agents such as polyvinyl alcohol-octadecyl isocyanate adduct (Japanese Patent Publication No. 297333) and polyethyleneimine-octadecyl isocyanate adduct (Japanese Patent Publication No. 40-17661) have been used. Had been me. Although these release agents have excellent properties in terms of quality, they use a large amount of organic solvent at the time of coating, so a solvent recovery process is required due to problems such as deterioration of working environment and pollution, With the rise in the price of solvents, the demand for aqueous release agents is increasing.

As an aqueous release agent, a monomer having an acidic group,
A mixture of an emulsion of a copolymer composed of other monomers and an emulsion of octadecylethylene urea (Japanese Patent Publication No. 52-6385) has been known. However, such an emulsion mixture-type aqueous release agent needs to be treated at a high temperature in order to cause a reaction between the copolymer and octadecylethylene urea at the time of drying after coating, and is used only for a substrate that can withstand high temperatures. There was a problem that it was not possible.

[Problems to be Solved by the Invention] As a result of repeated studies on a release agent that can be used by diluting with water and that can be used for a wider range of substrates, a polymer obtained by grafting a long chain alkyl group to a polyamine is post-emulsified. As a result, they have found that the problem can be solved, and have completed the present invention.

[Means for Solving the Problems] The present invention uses an aqueous dispersion obtained by post-emulsifying a long-chain alkyl graft polymer obtained by reacting polyvinylamine or polyallylamine with an alkyl isocyanate. Water-based release agent.

 Hereinafter, the present invention will be described in detail.

Conventionally reported aqueous release agents include a long-chain alkyl having a functional group such as an ethylene urea group, an N-methylol group, or a metal salt of a carboxylic acid, and a functional group capable of reacting with the long-chain alkyl. Are emulsified and then mixed. These products have conflicting demands that the reaction must be completed in a short drying step after coating, despite the need to suppress the reactivity in order to stably exist in the emulsion state. To answer, it was necessary to react at high temperature.

On the other hand, the aqueous release agent obtained by post-emulsifying the long-chain alkyl graft polymer of polyvinylamine or polyallylamine of the present invention has good storage stability and requires a reaction in the drying process after coating. Because of the absence of high-temperature treatment, high-temperature treatment is unnecessary, and it can be used for pressure-sensitive adhesive tapes and sheets using a substrate that cannot withstand high-temperature treatment.

The long-chain alkyl graft polymer used in the present invention, polyvinylamine or polyallylamine,
It can be produced by reacting an alkyl isocyanate having an alkyl chain having 8 or more carbon atoms.

As the polyvinylamine used in the present invention, allylamine or a modified product thereof, in addition to unmodified polyvinylamine and polyallylamine, as comonomers, olefins such as ethylene and propylene, acrylamide, methacrylamide, N, N-dimethylacrylamide and the like Acrylamides, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, unsaturated carboxylic acids such as fumaric acid and its esters and anhydrides, sulfonic acid monomers such as vinylsulfonic acid, dimethylaminoethyl methacrylate, vinylimidazole, Vinyl pyridine,
Copolymerized modified products of polyvinylamine and polyallylamine containing one to several kinds of monomers such as cation-modified monomers such as vinyl succinimide, allyl acetate, vinyl alcohol, and allyl alcohol. Further, such polyvinylamine, allylamine or a modified product thereof may be further modified.

Alkyl isocyanate used in the present invention,
A monovalent isocyanate having an alkyl group having 8 or more carbon atoms, and particularly having a carbon number from the viewpoint of releasability and availability.
Those having 12 to 30 alkyl groups are desirable. Examples thereof include long-chain alkyl isocyanates such as dodecyl isocyanate, tridecyl isocyanate, tetradecyl isocyanate, pentadecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, nonadecyl isocyanate, and eicosyl isocyanate.

The reaction of isocyanate with polyvinylamine or oriallylamine is mainly an aromatic organic solvent such as toluene or xylene, or an ester organic solvent such as ethyl acetate, or an aliphatic or alicyclic hydrocarbon organic such as cyclohexane or hexane. The reaction is performed in a solvent or the like, and a long-chain alkyl graft polymer can be obtained as a solution in an organic solvent. If necessary, mix this solution with a hydrophilic solvent such as isopropanol to precipitate the polymer,
By drying, the long-chain alkyl graft polymer can be obtained as a powder.

The aqueous release agent of the present invention can be obtained by emulsifying the long-chain alkyl graft polymer by a general method. Specifically, it can be obtained by stirring and mixing an organic solvent solution of a long-chain alkyl graft polymer in an aqueous solution of a surfactant to emulsify, and then removing the organic solvent as necessary. Further, the long-chain alkyl graft polymer and the surfactant can be emulsified and dispersed using a pressure kneader, a colloid mill or the like in the presence of water without using an organic solvent.

The type of surfactant used in the post-emulsification of the present invention is not particularly limited, but those having a relatively high hydrophilicity capable of forming an O / W emulsion upon emulsification are preferred.
Specific examples include polyoxyethylene nonyl phenyl ether, nonionic surfactants such as polyoxyethylene stearyl ether, sodium lauryl sulfate,
Anionic surfactants such as sodium polyoxyethylene nonylphenyl ether sulfate, or cationic surfactants such as stearylamine acetate and stearyltrimethylammonium chloride can be used.

The amount of the surfactant is preferably 3 to 30% by weight based on the long-chain alkyl graft polymer. If the amount is less than this, it is difficult to form a stable emulsion.

The aqueous release agent of the present invention can be applied by a general application device. Specific examples include a roll coater, a gravure coater, and a lip coater.

Further, as a substrate to which the release agent of the present invention can be applied, polyethylene, polypropylene, polyester, a prosthetic film such as cellophane, high-quality paper, kraft paper,
In addition to crepe paper, glassine paper, and the like, impregnated paper, plastic-coated paper, and the like, paper, cloth, and the like provided with a seal are provided.

In applying the aqueous release agent of the present invention to a plastic film such as polyester, cellophane, or polypropylene, a hydrophilic organic solvent may be added to the coating solution as needed. In particular, low molecular weight alcohols are suitable, and specifically, methanol, ethanol, isopropanol, n-propanol and the like can be used. Also,
Commercially available wetting agents and wetting improvers, specific examples thereof include Surfynol 465 (Nissin Chemical Industry Co., Ltd.) Byk-181 (Big Chemie Japan Co., Ltd.) and Nopcpwet SN-20T
(Sannobuco Inc.) can also be used.

[Examples] The present invention will be specifically described in the following examples, but the present invention is not limited thereto.

Synthesis Example 1 In a reactor equipped with a stirrer, a cooler, and a dropping funnel, dispersed in 10 parts by weight of polyvinylamine and 135 parts by weight of toluene, 48 parts by weight of octadecyl isocyanate was added, and the mixture was further refluxed for 3 hours. Distill toluene and remove nonvolatile matter
By concentrating to 40 wt%, a toluene solution of a polyvinylamine-octadecyl isocyanate adduct was obtained.

Dissolve 8 parts by weight of cationic surfactant (stearyltrimethylammonium chloride) in 142 parts by weight of water,
100 parts by weight of the above toluene solution was added, and the mixture was stirred with a homogenizer at 70 ° C. for 30 minutes to obtain an aqueous dispersion of a polyvinylamine-octadecyl isocyanate adduct.

Synthesis Example 2 A toluene solution of a polyallylamine-octadecyl isocyanate adduct was obtained in the same manner as in Synthesis Example 1 using 10 parts by weight of polyallylamine and 35 parts by weight of octadecyl isocyanate. An aqueous dispersion of a polyallylamine-octadecyl isocyanate adduct was obtained in the same manner as in Synthesis Example 1 using 10 parts by weight of a nonionic surfactant (polyoxyethylene nonylphenyl ether HLB 17.5).

Example 1 The aqueous dispersion of Synthesis Example 1 was diluted with water to prepare a coating solution containing 0.6% of the active ingredient, and a performance test was performed by the following method. The results are shown in Table 1.

Example 2 The aqueous dispersion of Synthesis Example 2 was diluted with 10% n-propanol to prepare a coating solution having an active ingredient of 0.6%, and a performance test was performed by the following method. The results are shown in Table 1.

Comparative Example 1 A commercially available toluene solvent-based polyethyleneimine-octadecylisoyanate adduct was mixed with toluene at a solid content of 0.6.
% Was used as a coating solution, and a performance test was performed by the following method. Table 1 shows the results.

Comparative Example 2 A polyallylamine diluted to a solid content of 0.6% with 10% n-propyl alcohol was used as a coating solution, and a performance test was performed by the following method.

Comparative Example 3 OPP, P with no release agent applied as a blank
The following tests were performed on ET film and paper.

[Release performance test method] The above coating solution was applied to biaxially oriented polypropylene (hereinafter referred to as OP).
P), a polyethylene terephthalate (hereinafter PET) film was applied to the corona discharge treated surface and high quality paper. The coating amount at this time is equivalent to 0.04 g / m ² . After drying at 100 ° C. for 2 minutes, a rubber-based adhesive tape (Orien Tape manufactured by Sekisui Chemical) was pressure-bonded to the coated surface with a roller of 2 kg of its own weight, and cut into a tape size to obtain a test piece.

Peeling performance was evaluated by measuring the peeling resistance and the residual adhesive strength of the test piece stored at 60 ° C. and 85% RH for 4 days. Peeling resistance is 300mm / min.
As for the resistance at 90 ° peeling, the residual adhesive strength was measured as the resistance at 180 ° peeling at a peeling speed of 300 mm / min by reapplying a tape of a sample piece to a stainless steel test panel.

[Dilution Stability Test] Each of the above aqueous dispersions was diluted with water to 1% by weight of the active ingredient, placed in a test tube, and allowed to stand for 24 hours, and evaluated based on the following criteria.

：: The entire surface was uniform, and there was no change at all. ×: Two layers were separated.

○: Can be written ×: Can not be written [Effects of the Invention] The aqueous release agent of the present invention has the same performance as a widely used solvent-based release agent while being aqueous, has excellent coatability and transparency, and is excellent in paper, polyester, and cellophane. ,
It can be used for back surface treatment of pressure-sensitive adhesive tapes or sheets of a wide range of substrates such as plastic films such as OPP. In addition, it has an appropriate release property, which is an advantage of a solvent-type long-chain alkyl-based release agent, and has good laminating properties and writing properties.

Continuation of the front page (56) References JP-A-51-13836 (JP, A) JP-A-58-52396 (JP, A) JP-A-52-151328 (JP, A) JP-A-52-7883 (JP) JP-A-51-23491 (JP, A) JP-B-40-17661 (JP, B1) JP-B-57-42103 (JP, B2)

Claims (1)

(57) [Claims] 1. An aqueous release agent characterized by using an aqueous dispersion obtained by post-emulsifying a long-chain alkyl graft polymer obtained by reacting polyvinylamine or polyallylamine with an alkyl isocyanate.