JPS6067579A - Removable adhesive - Google Patents

Abstract

PURPOSE:A removable adhesive, containing a surfactant in an acrylic or methacrylic adhesive, removable even at high temperatures without leaving the adhesive on the adherend at all, and suitable for masking tapes, sheets, labels, etc. CONSTITUTION:A removable adhesive obtained by incorporating (A) 100pts.wt. adhesive consisting essentially of an acrylic or methacrylic acid ester, e.g. a polymer consisting of an acrylic acid ester having a 4-12C alkyl group, butyl acrylate and vinyl acetate, etc., preferably a copolymer obtained by copolymerizing further a functional monomer therewith (B) preferably 1-10pts.wt. phosphoric acid based surfacant, e.g. a compound of formula I or II and derivatives thereof, particularly a mixture of monoester with diester of an alkyl phosphate having an 8-12C alkyl group and a salt thereof. In manufacturing a product, the viscosity is adjusted to 1,000-50,000cP, and the resultant adhesive is transferred to a support, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive that can be coated onto a tape or sheet to provide a removable adhesive tape or sheet.

More specifically, the present invention relates to an adhesive for heat-resistant masking tapes or sheets that is removable even when exposed to high temperatures during baking coating using thermosetting paint.

Conventionally, heat-resistant masking tapes have been produced by using a synthetic resin film or resin-impregnated crepe paper or Japanese paper as a support, and applying an adhesive made of rubber or acrylic polymer thereon. However, these adhesives can be used at high temperatures (120 to 16
0°C), and the adhesive strength of the adherend increases significantly, making it difficult to peel off the tape after baking and drying, and even if it is peeled off, the adhesive remains on the adherend, so-called Glue remains, which significantly impairs the beauty of the adherend.

The present inventors have found that a solution to these problems (after extensive research) is that by adding a phosphate ester surfactant to an acrylic adhesive, it can be easily peeled off even when exposed to high temperatures, and It was discovered that no adhesive remained on the adherent, and the present invention was completed.

That is, the present invention is a removable adhesive characterized by containing a phosphate ester surfactant in an adhesive containing (meth)acrylic ester as a main component.

Since the adhesive of the present invention is a heat-resistant removable adhesive,
Ideal as an adhesive for masking tapes, sheets, labels, etc. that require heat resistance.

This heat-resistant removable adhesive is applied to a support,
It can be attached to various adherends in the form of labels, sheets, tapes, etc., and can be easily peeled off even after being heated at a high temperature of 120°C or higher for 30 minutes or more (JIS Z023
180° peeling sticky crab according to 7 750 jj
/ 25 mm or more), and does not leave any adhesive force on the adherend and does not cause contamination.

The adhesive containing (meth)acrylic acid ester as a main component of the present invention refers to (meth)acrylic acid ester in which the alkyl group has 4 or more carbon atoms, preferably up to 12 carbon atoms, such as butyl acrylate, butyl methacrylate, etc. , acrylic acid-2-
Ethylhexyl, 2-ethylhexyl methacrylate,
40 to 99% by weight of lauryl acrylate, lauryl methacrylate, octyl acrylate, octyl methacrylate, etc., and an unsaturated monomer copolymerizable with the (meth)acrylic ester, such as (meth)acrylic acid, ( Methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, (meth)acrylamide, N-methylol (meth)acrylamide, (meth)acrylic ester, 2-hydroxyethyl (meth)acrylate, (
Hydroxypropyl meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, N,N-dimethylamineethyl (meth)acrylate, cyclohexyl (meth)acrylate, (meth)acrylate Phenyl acrylate, styrene, α-methylstyrene, vinyltoluene, vinyl acetate, vinyl fropionate,
Any polymer consisting of vinyl methyl ether, vinyl pyrrolidone, vinyl chloride, butadiene, acrylonitrile, itaconic acid, maleic anhydride, etc. may be used. -Butyrol (meth)acrylamide, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, (meth)acrylic acid, (meth)acrylic acid N
It is preferable to use a polymer obtained by copolymerizing a functional monomer such as , N-dimethylaminoethyl, etc. with the above-mentioned unsaturated monomer. This is because the pressure-sensitive adhesive containing the functional monomer has excellent anchoring properties to the support and tends to have a strong cohesive force, resulting in good removability.

Further, the form of the adhesive used in the present invention is not particularly limited, and may be an emulsion type, a solution type, or another type.

The phosphate ester surfactant of the present invention is an anionic surfactant mainly composed of esters of alcohols and phosphoric acids, and is a phosphoric acid monoester and/or a phosphoric diester. and/or a salt of a phosphoric acid ester and a basic compound. For example, examples of phosphate ester surfactants include the following.

(1) It is represented by an alkyl phosphate ester, R1 is an alkyl group having 4 or more carbon atoms, a 5- or alkenyl group, an alkylphenyl group, or a phenyl group, and R2 is hydrogen or an alkyl group having 4 or more carbon atoms. or alkenyl group or alkylphenyl group, phenyl group theal.

, R1 is an alkyl group, alkenyl group, alkylphenyl group, or phenyl group having 4 or more carbon atoms, and R2 is hydrogen, an alkyl group, alkenyl group, alkylphenyl group, or phenyl group having 4 or more carbon atoms. Al〇(3) Derivatives of phosphate esters Combinations of the alkyl phosphate esters (1) above and the polyoxyethylene alkyl phosphate esters (2) with metals such as sodium, potassium, calcium, zinc, barium, magnesium, aluminum, etc. It may be a salt, or a salt with an organic amine such as monoethanolamine, jetanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine, trimethylamine, butylamine, pyridine, or an ammonium salt.

Among the above-mentioned phosphate ester surfactants, alkyl phosphate esters and their derivatives have good miscibility with adhesives containing (meth)acrylic ester as a main component (preferably, carbon atoms are 8 More preferred are alkyl phosphoric acid esters and derivatives thereof having ~12 alkyl or alkenyl groups or alkylphenol groups.

In particular, mixtures of monoesters and diesters of alkyl phosphoric esters having an alkyl group having 8 to 12 carbon atoms, more preferably monoester/diester=3
It is advantageous to use alkyl phosphoric esters and their salts in a molar ratio of 0 to 70/70 to 30.

Moreover, it is preferable to use sodium salt, potassium salt, monoethanol salt, and jetanol salt of alkyl phosphate ester.

In the present invention, one or more of the above-mentioned phosphate ester surfactants may be used.

To add a phosphate ester-based surfactant to an adhesive whose main component is (meth)acrylic ester, it can be added during or after polymerization of the adhesive, and the amount of addition is based on (meth)acrylic ester. It may be added in an amount of about 1 to 10 parts by weight per 100 parts by weight of the adhesive as the main component. If the amount is less than 1 part by weight, the effect of adding the phosphate ester surfactant will not be sufficiently exhibited, and if it exceeds 10 parts by weight, the performance as an adhesive will tend to deteriorate.

A crosslinking agent such as a polyisocyanate compound, a melamine compound, or an epoxy compound may be added to the adhesive of the present invention.
Furthermore, pigments such as titanium oxide and Merck, which are generally mixed in adhesives, or stabilizers can also be added.

The adhesive of the present invention can be made into adhesive products such as sheet tapes and labels using synthetic resin films such as polyester, polypropylene, polyethylene, polyvinyl chloride, and cellulose acetate, or cloth, paper, aluminum laminated paper, metal foil, etc. as a support. To manufacture these adhesive products, you can
For example, the pressure-sensitive adhesive of the present invention is generally about 1,000 to 5,000
Adjust the adhesion to 0 centipoise, roll coater,
It may be transferred or directly coated onto a support using a commonly used adhesive coating machine such as a doctor coater.

The adhesive of the present invention is suitable as an adhesive for heat-resistant masking tapes, but it can also be used as an adhesive for so-called surface protection films for metal plates such as stainless steel and aluminum, decorative plates, glass plates, and the like.

Next, the present invention will be explained using examples. In addition, "parts" and "%" in Examples, Synthesis Examples, and Comparative Examples indicate "parts by weight" and "% by weight," respectively.

Synthesis Example 1 31.9 parts of ethyl acetate is charged into a reactor equipped with a stirrer, a reflux condenser, a dropping device and a thermometer, and heated to 80°C. This product was mixed with 33.2 parts of 2-ethylhexyl acrylate, 3.7 parts of vinyl acetate, and 2.2 parts of acrylic acid under a nitrogen atmosphere.
5 parts of acrylamide, 04 parts of acrylamide, and 0.1 part of glycidyl methacrylate, and 79 parts of ethyl acetate in which 0.2 parts of benzoyl peroxide were dissolved were each added dropwise over 2 hours.

Next, 200 parts of ethyl acetate containing 0.1 part of dα-inbutyroazobisnitrile was added dropwise over 2 hours, and the polymerization reaction was further continued at 80° C. for 4 hours. In this way, a pale yellow acrylic adhesive solution with a solid content of 391% and a viscosity of 2200 cps was obtained.

Synthesis Example 2 22.4 parts of ethyl acetate and 0.4 parts of acrylamide were placed in a reactor equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer.
and heat to 80℃.

To this, 1.5 parts of ethyl acrylate under a nitrogen atmosphere,
A mixture of 15.2 parts of butyl acrylate, 15.2 parts of 2-ethylhexyl acrylate, and 3.1 parts of acrylic acid and 49 parts of ethyl acetate in which 0.1 part of benzoyl peroxide was dissolved were each added dropwise over 2 hours.

10- Then toluene containing 0.03 parts of benzoyl peroxide 13.
After a mixture of 5 parts and 23.7 parts of ethyl acetate was added dropwise over 2 hours, the polymerization reaction was further continued at 80°C for 4 hours. A pale yellow acrylic adhesive solution with a solid content of 35.3% and a viscosity of 3800 cps was thus obtained.

Synthesis Example 3: In a reactor equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer, 31.8 parts of water, 2.1 parts of polyoxyethylene nonylphenol (HLB 13.3), and 2.0 parts of sodium dodecylbenzenesulfonate were added. Prepare the ingredients and dissolve. To this was added a monomer mixture of 6.5 parts of vinyl acetate, 20.5 parts of 2-ethylhexyl acrylate, 255 parts of butyl acrylate, and 26 parts of methacrylic acid, and 8.8 parts of water containing 02 parts of potassium persulfate under a nitrogen atmosphere. 20% of the radical polymerization initiator aqueous solution dissolved in each was added and heated to 80°C. After continuing the reaction for 30 minutes, the remaining monomer mixture and 80% of the radical polymerization initiator aqueous solution were added dropwise over 2 hours, and the polymerization reaction was further continued at 80° C. for 6 hours. A milky white acrylic adhesive emulsion with a solid content of 55.1% and a viscosity of 7200 cps was thus obtained.

Examples 1 to 3゜To the acrylic adhesive solution obtained in Synthesis Examples 1 to 2 and the acrylic adhesive emulsion obtained in Synthesis Example 3, a monomer was added as a phosphate ester surfactant to 100 parts of the polymer. Mixture of lauryl phosphate and dilauryl phosphate (monoester/diester = s o / 5
After adding 5 parts of each jetanolamine salt (molar ratio) as shown in Table 1 and mixing thoroughly, a coating film of 25 μm after drying was applied to a 25 μm polyester film treated with corona discharge using an applicator. The coating was applied to a thickness of .

It was then dried at 105°C for 3 minutes and laminated with release paper to evaluate its performance as a heat-resistant removable adhesive.
As shown in , all of them had excellent performance as adhesives and excellent heat-resistant removability.

Comparative Examples 1 to 3゜Acrylic adhesive solutions obtained in Synthesis Examples 1 to 2 and acrylic adhesive emulsions obtained in Synthesis Examples were prepared in the same manner as in Example 1 to determine their performance as heat-resistant removable adhesives. As a result of evaluation, as shown in Table 1, no pressure-sensitive adhesive with good heat-resistant removability was obtained.

-13- -14 Examples 4 to 7 Polymer 10 was added to the acrylic adhesive solution obtained in Synthesis Example 1.
Mixture of monolauryl phosphate and dilauryl phosphate (monoester/diester-56
/44 (molar ratio)) was added in the ratio shown in Table 2, and after thorough mixing, the mixture was treated in the same manner as in Example 1, and had excellent performance as a heat-resistant removable adhesive.

Comparative Examples 4 to 5 Polymer 10 was added to the acrylic adhesive solution obtained in Synthesis Example 1.
A mixture of monolauryl phosphate and dilauryl phosphate (monoester/diester=56
/44C molar ratio]) were added in the proportions shown in Table 2, and after thorough mixing, the performance as a heat-resistant removable adhesive was evaluated in the same manner as in Example 1. the result,
As shown in Table 2, Comparative Example 4 had poor removability, Comparative Example 5 had significantly insufficient adhesive strength and holding power, and its performance as an adhesive was insufficient. -15- A heat-resistant removable adhesive was not obtained in any of the cases of Comparative Example 5.

-16- Test method Adhesive strength: The 180°C peel adhesive strength was measured using an Instron type tensile tester against a test plate specified in JIS Z-0237. The test plate is SUS 30
4 was used.

□ Holding force: The time required for the sample to fall was measured at 40° C. under a load of 1 yu according to the method for measuring holding force stipulated in JIS z-0237. Note that if the sample did not fall after 60 minutes, it was expressed as N/C. 5US30 for the test board
4 was used.

Tack; JIS z-o23rVc regulation 1t.

The tack was measured.

Re-peelability: A test piece was affixed to each test plate, crimped twice with a 2 kg rubber roll, stored in an atmosphere of 23°C and 65% RH for 7 days, and then peeled off. A sample that could be peeled off and had no adhesive residue on the adherend was considered acceptable.

-18- Heat-resistant re-peelability: A test piece was attached to each test plate, and pressed back and forth twice with a 2 kg rubber roll, and then peeled at 120°C or 160°C.
It was stored for 30 minutes at a temperature of .degree. C., cooled to room temperature, and then evaluated in the same manner as for removability.

patent applicant Daicel Chemical Industries, Ltd. -19-

Claims (1)

[Claims] Adhesive containing (meth)acrylic acid ester as a main component -
; characterized by containing a phosphate ester surfactant;
72,', Removable adhesive.