JPS58118873A - Preparation of self-adhesive film - Google Patents

Abstract

PURPOSE:To prepare an adhesive film with excellent adhesive properties, by adding a small amount of solvent to a photosensitive compson. which contains a polymer with photopolymerizable vinyl group and a photosensitizer, coating a base film with a compsn. and irradiating it with actinic ray to effect photopolymerization. CONSTITUTION:A photopolymerizable vinyl group-contg. polymer (A) obtained, e.g., by copolymerizing a vinyl compd. (e.g. ethyl acrylate) with a carboxyl group-contg. monomer (e.g. acrylic acid) and reacting a vinyl and glycidyl group- contg. monomer (e.g. glycidyl acrylate) with a part of carboxyl groups of the copolymer, a photosensitizer (B) (e.g. 2-ethylanthraquinone) and a solvent (e.g. acetone) used in 0.6-10% based on the total weight of (A) and (B), are blended together. The resultant photosensitive compsn. is applied over a base film and then irradiated with actinic ray to effect photopolymerization.

Description

[Detailed description of the invention] The present invention relates to a method for producing an adhesive film.

Conventionally, adhesive films are prepared by applying a liquid mixture containing, for example, a thermal crosslinking agent and a polymer having an active group for the thermal crosslinking agent onto a base film.

Then, the thermal crosslinking agent and the polymer are reacted through a heating step 9
It is manufactured by crosslinking the polymer and evaporating the organic solvent contained in the mixture to form an adhesive film.

However, in the production method of such a thermosetting adhesive film, (1) long-time drying and use of a large amount of solvent for thermal cross-linking reaction and solvent evaporation are undesirable from the viewpoint of energy saving and resources; (2) The above-mentioned mixed solution containing the thermal cross-linking agent and polymer cannot be stored for a long period of time because the reaction between the thermal cross-linking agent and the polymer proceeds gradually even at room temperature. There are six problems, such as the cross-linking reaction does not proceed sufficiently simply by spreading the mixed solution on the substrate and heating it, and the adhesive film must be aged for several days after being rolled.

In recent years, several attempts have been made to improve these drawbacks.

Dutch patent #Ea601,711 proposes a method and apparatus for producing an adhesive film, in which an acrylic monomer or oligomer is polymerized by irradiating ultraviolet rays on a film base material, and an adhesive is coated on the base material. This paper describes a method for producing an adhesive film that is cured by irradiation with ultraviolet rays in an atmosphere where air is blocked by an inert gas or the like. According to this method, the above-mentioned problem is improved, but new problems arise such as roughness of the adhesive layer due to polymerization shrinkage, and adjustment of the permissible oxygen concentration using an inert gas is difficult to implement industrially. be.

Furthermore, JP-A-54-17942 discloses that 2-ethylhexyl acrylate i9 is made into an adhesive by photopolymerizing a composition consisting of butyl acrylate, N-vinyl-2-pyrrolidone, and a sensitizer. However, the problems have been improved.

This composition does not harden stably in air, so it is still unsuitable for industrial implementation.

According to Japanese Patent Publication No. 51-5664, an adhesive is produced by photopolymerizing the olefinic unsaturated bonds present in an acrylic polymer with a molecular weight of 1,000 ml and crosslinking it. Although the above problem (2) is improved, a large amount of solvent is used and photopolymerization is merely used for crosslinking, so the above problem (1) is not solved.

The present inventors solved the above problems (1) and (2) at the same time, and successfully photocured the present invention in air with vine lid,
We have made extensive efforts to obtain an adhesive with excellent adhesive properties, but we found that adhesive compositions that do not contain any solvent have poor photocurability in air and are only good at oxygen concentrations of 100 ppm or less. It did not photocure. The adhesive strength of this cured adhesive layer is greatly reduced at high temperatures.Surprisingly, the present inventors have found that, as described above, when a small amount of solvent is included in the composition, it is good even in air. The present invention provides a method for producing an adhesive film that has good photocurability even in air and has sufficient adhesive strength even at high temperatures. It is something to do.

In the present invention, on a film base material, a photosensitive composition containing a polymer having a photopolymerizable vinyl group and a photosensitizer is added with a solvent α6 relative to components other than the solvent in the photosensitive composition.
The present invention relates to a method for producing an adhesive film in which the adhesive film is photopolymerized by irradiating active light in a state containing ~10% by weight.

Although the details of why the solvent present in the photosensitive composition strongly promotes photocuring are not clear.

This is presumed to be due to the solvent acting as a good hydrogen donor for the sensitizer.

Incidentally, in recent years, the use of electron beams as a curing method has been increasing, but electron beam irradiation equipment is expensive and difficult to handle due to safety and other issues, making it extremely difficult to implement it industrially. Although it is considered that the wavelength is 250n
An active light irradiation device that mainly uses ultraviolet light in the wavelength range from m to 500 nm is inexpensive and does not require special care in handling. According to the invention, by irradiation with actinic light.

An adhesive film exhibiting excellent properties can be obtained.

The method for separately producing the photopolymerizable vinyl group-containing polymer used in the present invention is 1. For example, a divinyl compound and a carboxyl group-containing monomer are copolymerized by an ordinary solution polymerization method in a suitable organic solvent. There is a method of introducing vinyl groups into a polymer by reacting a monomer having a vinyl group and a glycidyl group with a part of the carboxyl groups of the nine-copolymer obtained after washing in the presence of a polymerization inhibitor and a catalyst. be. At this time, the concentration of photopolymerizable vinyl groups in the electropolymer having photopolymerizable vinyl groups is preferably 2°xlo P equivalent/P- or less.

If it exceeds this range, it tends to overcur and the adhesive strength decreases.

Examples of the above vinyl compounds include alkyl C methane acrylate (meaning alkyl acrylate or full methacrylate).

(same below), vinyl acetate, acrylnitrile.

Styrene, butadiene, heptatalic anhydride, arylamide, Nt-butylacrylamide, polymerizable alligator conductors of these compounds, and the like are used.

Examples of alkyl (meth)acrylates include methyl C meth)acrylate, ethyl (meth)acrylate,
Examples include butyl (meth)acrylate, isobutyl (meth)acrylate, octadecyl (methane acrylate, 2-ethylhexyl (meth)acrylate, etc.).

As a monomer having nine vinyl groups and glycidyl groups, 1
Examples include glycidyl (meth)acrylate.

The photosensitive composition of the present invention may contain a liquid addition polymerizable substance having at least one radically polymerizable unsaturated group, for example #12-ethylhexyl (
Meta) acrylate.

2 Acrylic (methane acrylate, tridecyl (meth) 7
Acrylate, stearyl (meth)acrylate, polyethylene glycol 7-(meth)acrylate, polyethylene glycol mono(meth)7-acrylate, methoxypolyethylene glycol acrylate, 2-hydroxydodecyl (meth)acrylate, Aronix X-
511A (Toagosei Chemical Co., Ltd. #I41111 trademark monoacrylate), Aronix M-5500 (]ll[nitrate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth(meth)acrylate, polyethylene glycol di(meth)acrylate] If the amount of acrylate is too large based on the copolymer, it will adversely affect adhesive properties such as adhesive strength, so it is preferably 30 parts by weight based on 100 parts by weight of the polymer having a photopolymerizable vinyl group. The glass transition temperature of the photopolymerizable vinyl group-containing polymer of the present invention is preferably -30°C or lower in order to obtain good adhesive properties; if it is higher than this, the tack will decrease. , and the photocurability also tends to decrease.
% is preferably from -50°C to -70°C. Maku,
The weight average molecular weight of the polymer is 000 to 100.00.
A value in the range of 0 is preferable; if it is less than 3,000, the photopolymerization speed will decrease, and if it exceeds 100,000, the viscosity will be too high and high solid coating will tend to become difficult. The weight average molecular weight range is particularly preferably from 5.000 to 5.000.

Examples of solvents to be included in the photosensitive composition include acetone and methyl ethyl ketone.

Methanol, ethanol, butanol, imprho Tanol9. Toluene, xylene, Sesolv.

Ethyl sesolv, phenol, ethyl acetate.

Styrene, trichlorethylene, tetrachloride ml methylene chloride, etc. are mentioned.

The amount of the solvent contained in the photosensitive composition needs to be 0.6 to 10% by weight relative to the components other than the solvent in the photosensitive composition, and the preferable content for 41 is 1 to 5% by weight. %. In order to prevent inhibition of photopolymerization by oxygen, if the amount is less than 0.6% by weight, it will be evaporated and removed by irradiation, which is a problem from the viewpoint of saving resources and reducing pollution. Furthermore, the good solvent that evaporates is exposed to light.
□There is a strong possibility that the lamp of the irradiation machine will be contaminated and that the solvent will remain in the adhesive layer even after polymerization, in which case the remaining good solvent will evaporate over time and will have a negative impact on adhesive properties such as adhesive strength. It is.

A photosensitive composition can be obtained by adding a photosensitizer to a polymer having a polymerizable vinyl group or, if necessary, the above-mentioned liquid addition polymerizable substance. However, there are no particular restrictions on the photosensitizer KFi that can be used here. However, it is preferable to use a substance that is activated by actinic light, is not thermally activated at temperatures below 200° C., and has extremely low volatility. These substances include substituted and unsubstituted polynuclear compounds such as 2-ethylanthraquinone,
2-Tertiary-butylant-2-quinone, octamethylanthraquinone, 1.2-benzanthraquinone, 2.
3-diphenylanthraquinone etc. can be used. Other useful ones include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, diphenyl monosulfide, acetophenone, benzophenone, 44'-bisdiethylaminobenzophenone, 2,4,5-tri can. The blending amount of these photosensitizer systems is 1 to 15 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of components other than the photosensitizer in the photosensitive composition.

In the present invention, the film base material on which the photosensitive composition that is the adhesive composition is formed is.

There are no particular limitations on the material as long as it is not affected by the composition; for example, polyvinyl chloride film.

Polyester film, acetate film.

Can remove incorrect paper, release paper, etc. Photosensitive composition t
Method of coating on the tI film A known method can be used, such as a roll coater, a coater in a roll coater, a knife coater, a gravure coater, or the like. After coating, irradiation with active light -' is carried out using a mercury lamp or the like, and it is preferable to use a mercury lamp as the main component.

The photosensitive composition in the present invention may contain a chain transfer agent, a pigment, a dye, etc. depending on the WK.

Next, the present invention will be explained in more detail with reference to Examples.

Here, parts and parts represent 1 part by weight and 1% by weight.

Example 1 50 parts of toluene was poured into a four-loop flask equipped with a stirrer, a temperature needle, a dropping funnel, and a nitrogen gas blowing device.
Raise the temperature to 5°C. Next, 8117 parts of 2-ethylhexyl acrylate and 3 parts of methyl methacrylate were added while stirring while maintaining the temperature at 95°C.

6 parts of acrylic acid, 17 parts of azobisisobutyronitrile,
A mixed solution consisting of 50 parts of doluol was added dropwise through a dropping funnel over a period of 3 hours to obtain a ternary copolymer.
A mixed solution consisting of 15 parts of glycidyl methacrylate, 4.6 parts of glycidyl methacrylate, and 1.5 parts of ethyl cellosolve was added dropwise over 30 minutes.
By raising the temperature by 100"CK and continuing the reaction in this state for 14 hours, a copolymer solution with a viscosity of about 150 cps/23°C, a glass transition temperature of about -70°C, a weight average molecular weight of about 10,000 was obtained. 200 parts of benzophenone, 2.5 parts of N,N-diethylaminobenzophenone α
5 parts were added to prepare a photosensitive composition.

(3) The queen photosensitive composition was applied onto a 60 μm thick polyethylene film using an applicator.

Air drying (25°C for 5 hours) was performed. The amount of residual solvent in this product was 5% (based on analysis using a gas chromatograph 2), which was the same as the weight % based on components other than Anatomy 6 in the photosensitive composition, and then in the air with a medium pressure mercury lamp (manufactured by Toshiba). )
An adhesive film was obtained by irradiating ultraviolet rays at 59mw7cm for 5 seconds. The adhesive layer thickness of this product was 5 μm.

Comparative Example 1 (Bl) The photosensitive composition described above was applied onto a 60 μm thick polyethylene film using an applicator.

Heat drying (80° C., 6 minutes) was performed. The amount of residual solvent in this product was found to be less than α01 (according to analysis using a gas chromatograph).

(b) In this, medium pressure mercury lamp (manufactured by Toshiba) 150m in the air
An adhesive film was obtained by irradiating ultraviolet rays at w/31 for 5 seconds. The adhesive layer thickness of this product was 5 μm.

(μ) In order to shield the above heat-dried material from oxygen in the air, use a polyethylene film with a thickness of 21
Laminate using Akebono Sangyo's A-500 model laminator with 4-layer pressure, and then a medium pressure mercury lamp (Toshiba 1fl).
The laminated polyethylene film was then peeled off at a rate of 5 QQssz/min to obtain an adhesive film II. The adhesive layer thickness of this film was set at 5 μm.

A sample piece of the adhesive film prepared as described above (8)-(I) and (B)-(B) was placed in a 5m×5
(Laminated with 2Kf weight on Ushi XIQm stainless steel plate) L
, The adhesive force of 180° peeling at a speed of 200 W/min was measured according to JIS C2107. The results are shown in Table 1.

Table 1 Photocurability and adhesive strength of various sample pieces *1j'/2s
1e means that the sample piece *2 thermally expands, peels off partially from the stainless steel plate, floats up, and becomes in good condition! As is clear from the above, the presence of residual solvent in the photosensitive composition has a large effect on the photocurability in air.

The photocurability in Table 1 above is "good" when the sample piece is laminated on a stainless steel plate under 2DI quadruple pressure.

When it was dried in a drying oven at 65°C for 7 days and then peeled off, it did not transfer to the adherend stainless steel plate at a peeling rate of 1 to 10' sum/min, causing no clouding or adhesion. It refers to something that is not there.

Example 2 A mixture of 75.2 parts of 2-ethylhexyl acrylate, 18 parts of methyl methacrylate, 6.8 parts of acrylic #, 7 parts of azobisinobutyronitrile, and 50 parts of toluene is prepared. Copolymerization was carried out in the same manner as in Example 1. Viscosity: 180 cps/23°C, glass transition temperature: about -58
A copolymer solution with a weight average molecular weight of about 11,000 was obtained at 9°C. This product was made into a photosensitive solution in the same manner as in Example I, and further coated on a polyethylene film and air-dried (25 DEG C. for 5 hours). The amount of residual solvent for this product was rated 5 and 6 good. Next, ultraviolet rays were irradiated in the same manner as in Example 1. The photocurability of this product was good, and both the adhesive strength at 23°C immediately after pasting and the adhesive strength after heating at 65°C for 7 days were excellent. Nine, instead of air-drying this product, heat drying at 80°C for 6 minutes will result in a residual solvent amount of 0.01'.
Even when irradiated for 36 seconds at lk or less, there was almost no photocuring.

Examples 3 to 10 Various copolymers were obtained by copolymerizing in the same manner as in Example 1 using the formulations shown in Table 2 below.

Iris 2 Table Continued *ITDA measurement value, *2 polystyrene equivalent, (monomer) was used for addition modification of the nine copolymer using the three components described above.

When the photocurability and adhesive strength of the polymers shown in Table 2 were examined according to the methods of Examples 1 and 2, the amount of residual solvent when air-dried (25°C for 5 hours) was 4 to 6, and both were Good photocurability, adhesive strength at 23℃ immediately after pasting, 65℃
After heating for 7 days, the adhesive strength was excellent.

9. Heat dry these Q items instead of air drying.
:) When the residual solvent amount of all the vegetables was 0.01- or less, it was irradiated for 36 seconds, and No. 41 was hardly photocured.

Example 11 The polymer of Example 2 was desolventized in a rotary Nino (porator) under reduced pressure (15 mmHg) at 50°C for 6 hours.The residual solvent of this product was 0.1- or less. Add a certain amount of.

Next, 2.5 parts of benzophenone and 0.5 parts of Michler's ketone were added to 100 parts of the solid content and stirred to prepare a photosensitive composition. Following Example 2, the polyethylene film Kll! Table 3 shows the results of evaluating the photocurability and adhesive strength of F cloth.

Example 12 Table 4 shows the evaluation results in Example 11 when a solvent other than toluene was used. The number of parts to be added is preferably 5 parts per 100 parts of components other than the solvent in the photosensitive composition.

Table 4 Example 13 Polymer 70 subjected to solvent removal as in Example 11
5 parts of toluene, 30 parts of Aroex X-511A (Toagosei Kagaku monoacrylate), 3 parts of benzophenone
The following steps from coating to polyethylene film to property evaluation were carried out in accordance with Example 2. As a result, the curing properties were good, and the adhesive strength was 1+ at 023°C immediately after application, and at 65°C.
After heating for 7 days, the adhesive strength was excellent.

Example 14 An experiment was conducted by replacing Aloex

Example 15 The number of parts of azobisisobutyronitrile in Example 2 was changed to 0.3.
Synthesis was carried out in the same manner as in Example 2 except that the number of parts of glycidyl methacrylate was changed to 0.5 parts. Viscosity is approximately 350 cps/23℃, glass transition temperature is approximately -6
A copolymer solution having a weight average molecular weight of 95,000 was obtained at 5°C. The following evaluation was carried out in accordance with Example 2. Air dry (2
The amount of residual solvent after 5 hours at 5°C was 7 -, and the photocurability of this product was good, and the adhesive strength at 23°C immediately after application was
After heating at 65° C. for 7 days, the adhesive strength was excellent.

In addition, nine items were heat-dried at 80℃ for 6 minutes instead of air-drying, and the remaining solvent amount was 0.05 seconds or less.
There was almost no photocuring even after irradiation for seconds.

Example 16 Parts of azobisisobutyronitrile in Example 2) 0.
Synthesis was carried out in the same manner as in Example 2 except that 6 parts of glycidyl methacrylate were used and 1 part of glycidyl methacrylate was used. Viscosity is about 2
A copolymer solution having a weight average molecular weight of 51,000 and a glass transition temperature of about -65°C and a weight average molecular weight of 51,000 was obtained. This product was evaluated for K, and the results were as good as in Example 15.

Example 17 16 parts of carbon tetrabromide was newly added to the dripping solution of Example 2, and the number of parts of glycidyl methacrylate was changed to 9.2 parts.Other than that, the synthesis was carried out in the same manner as in Example-2.
cps/23°C, a glass transition temperature of -70°C, and a weight average molecular weight of 4500. This product was evaluated and the results were as good as in Example 15.

According to the method for producing an adhesive film according to the present invention.

An adhesive film is provided that has good photocurability in air and has sufficient adhesive strength even at high temperatures.

Claims (1)

[Claims] 1. On a film base material, a solvent is added to a photosensitive composition containing a polymer having a photopolymerizable vinyl group and a photosensitizer to components other than the solvent in the photosensitive composition. Te 0.6-1
A method for producing an adhesive film, which involves irradiating actinic light and photopolymerizing a 0% mold-containing state. 2. The adhesive according to claim 1, wherein the polymer having photopolymerizable vinyl groups has a concentration of photopolymerizable vinyl groups of ZOXIO-") equivalent/? or less. A method for producing a film. & The adhesive film according to claim 1 or 2, wherein the polymer having a photopolymerizable vinyl group is a polymer having a photopolymerizable vinyl group having a glass transition temperature of 130° C. or less. 4. Particularly desired range of 1FFrfII Item 1, wherein the polymer having a photopolymerizable vinyl group is a polymer having a photopolymerizable vinyl group having a weight average molecular weight of 3,000 to IOQ,000;
A method for producing an adhesive film according to Tsuru item 2 or 3. (v) The photosensitive composition contains 30 parts by weight or less of a liquid addition polymerizable substance having at least one radically polymerizable unsaturated group per 100 parts by weight of a polymer having a photopolymerizable vinyl group. Claim 1, #
! A method for producing an adhesive film according to item 2, 3, or 4.