JPH025768B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION This invention relates to unsaturated polyester resin compositions. The unsaturated polyester resin composition of the present invention is
Useful as an adhesive for protective films. The protective adhesive sheet is applied to products that require surface protection, such as decorative plywood, acrylic boards, stainless steel boards, glass boards, etc., to prevent damage during cutting or transportation of these products.
An adhesive sheet for surface protection whose main purpose is to prevent discoloration and deterioration during long-term storage.
In recent years, its uses have been expanding more and more. Therefore,
The basic performance required of adhesive sheets for protection is that the adhesive does not transfer to the surface of the product during processing or storage, and that when it is peeled off, there will be no adhesive residue or cloudy phenomenon, and that it will not cause adhesive residue or clouding, and that it should not cause adhesive residue or clouding when it is peeled off. Because it is often applied to articles with complex surfaces, it must maintain appropriate adhesion and sufficient flexibility. Description of Prior Art Conventionally, protective adhesive sheets have been made of acrylic polymers, rubber polymers, or ethylene-based adhesive sheets.
The main component is vinyl acetate polymer, and if necessary,
It is manufactured by applying an organic solution or dispersion of additives such as a tackifier resin and plasticizer to a support such as a film or paper cloth, and then heating and drying it. Conventional protective adhesive sheets manufactured in this way, when protecting the surface of an adherend for a long period of time, have additives that migrate to the surface of the adherend, and when the adhesive sheet is peeled off, there is no adhesive residue or cloudiness. This resulted in a significant decrease in product value. In addition, all conventional methods include a heating process, which not only consumes a large amount of thermal energy, but also has problems such as limitations on the types of supports and additives, and the need to enlarge the production line. It was hot. Therefore, there has been a desire in the art for a protective adhesive sheet that can be applied and cured without heating and has excellent long-term protection performance for various types of decorative plywood. Summary of the Invention As a method for curing a liquid resin at room temperature, there is generally a method of irradiating a resin that can be cured by a radical chain mechanism with ionizing radiation, particularly an electron beam. Unsaturated polyester resin is a typical example of such liquid resin, but the cured product of this resin is generally characterized by extremely rigid physical properties, so conventionally glass fiber reinforced plastic (FRP)
It was used in paints, etc. The present inventors have conducted intensive research contrary to common knowledge regarding conventional unsaturated polyester resins, and have already provided a resin composition that exhibits strong adhesive properties by curing with electron beams (patent application). 55-72451), but in order to provide additional properties as a protective adhesive,
As a result of repeated research, as detailed below,
By curing an unsaturated polyester resin composition consisting of a specific unsaturated polyester and a specific vinyl monomer, it is possible to create an adhesive that has excellent long-term protection performance for various objects to be protected as a protective adhesive sheet. They discovered this and arrived at the present invention. Therefore, an object of the present invention is to solve these problems by coating an adherend without heating.
The object of the present invention is to provide a solvent-free liquid unsaturated polyester resin composition suitable for a protective pressure-sensitive adhesive sheet which has excellent long-term protection performance for various objects when cured. A further object of the present invention is to provide an adhesive useful as a protective film adhesive mainly consisting of an unsaturated polyester and a vinyl monomer having a 5- or 6-membered heterocycle having 1 or 2 nitrogen atoms as a substituent. An object of the present invention is to provide a saturated polyester resin composition. Furthermore, another object of the present invention is to provide a method for forming a protective film by coating and curing the unsaturated polyester resin composition of the present invention on the surface of an adherend without heating. Other objects and advantages of the present invention will become apparent in the following. Detailed Description of the Invention The unsaturated polyester resin composition of the present invention is mainly composed of an unsaturated polyester produced from a specific acid component and a specific alcohol component, and a specific vinyl monomer. The unsaturated polyester, which is one component of the product, contains an aliphatic unsaturated polybasic acid having 4 or more carbon atoms in an amount of 20 to 80 mol% of the acid component and 4 carbon atoms.
At least one kind of aliphatic saturated polybasic acid or alicyclic polybasic acid is used in an effective amount of 80 mol% or less of the acid component, and a polybasic acid having one or more carbon branched chains is used as the alcohol component. It is produced by polycondensation by heating using 50 mol% or more of alcohol. The aliphatic unsaturated polybasic acid used in the present invention has four or more carbon atoms, and preferred examples include maleic anhydride, fumaric acid, itaconic acid, and citraconic acid. These aliphatic unsaturated polybasic acids can be used as one type or as a mixture of two or more types in an amount of 20 to 80% of the acid component.
Used in a mole % range. In addition, examples of aliphatic saturated polybasic acids include succinic anhydride, succinic acid, adipic acid, azelaic acid, and sebacic acid, and examples of alicyclic polybasic acids include tetrahydrophthalic anhydride, cis-4-cyclohexane 1 , 2-dicarboxylic acid, hexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, tetraprobenylsuccinic anhydride, and the like. 80 ingredients
Any effective amount range not exceeding mol % can be used. Further, the polyhydric alcohol having a carbon branch chain used in the present invention includes propylene glycol,
Dipropylene glycol, 1,3-butanediol, 1,4-peptanediol, 2-ethylhexane 1,3-diol, 2,2-dimethylpropane 1,3-diol, 2,2,4-trimethylpeptane -1,3-diol is exemplified, and one or a mixture of two or more of these is used in an amount of 50 mol% or more of the alcohol component. Further, linear polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, and 1,4-butanediol can be used in an amount not exceeding 50 mol% of the alcohol component. An unsaturated polyester is produced by mixing the above components and subjecting them to polycondensation using a conventional method. The molecular weight is not particularly limited, but is suitably in the range of 1,000 to 10,000 in order to achieve compatibility with the monomers used or a viscosity that facilitates coating. Examples of the vinyl compound having a 5- or 6-membered heterocyclic ring containing 1 or 2 nitrogen atoms, which is one component of the composition of the present invention, include 2-vinylpyridine, N-vinylcarbazole, N-vinylpyrrolidone, 3-vinylpyridine, -vinylindole, N-vinylimidazole, etc. are exemplified. The amount of these monomers used is 0.1 to 15 mol, preferably 0.2 to 10 mol, based on the unsaturated bonds contained in the unsaturated polyester. The unsaturated polyester resin composition of the present invention is produced by mixing and dissolving the liquid vinyl monomer described above in the unsaturated polyester, which is one of the components of the present invention. The mixing ratio of both components at this time is preferably in the range of 0.1 to 15 molar equivalents of the vinyl monomer to the unsaturated bonds contained in the unsaturated polyester. The unsaturated polyester resin composition of the present invention is used as an adhesive for a protective film. Therefore, if it is necessary to adjust the protection performance depending on the type of adherend, add other radically polymerizable vinyl monomers to 30% of the total monomer amount.
They may be mixed and dissolved in an effective amount of parts by weight or less. Here, other radically polymerizable vinyl monomers have the general formula (R ₁ is H or CH ₂ ; R ₂ has 2 to 13 carbon atoms
Examples include acrylic ester monomers represented by (alkyl groups), styrene, divinylbenzene vinyl acetate, etc. Furthermore, additives (materials) well known in the art such as fillers such as calcium carbon and titanium oxide and/or anti-aging agents can be added to the unsaturated polyester resin composition of the present invention, if necessary. . However, a major feature of the present invention is that it does not require additives such as tackifying resins and plasticizers that are commonly used. The method of curing the liquid unsaturated polyester resin composition of the present invention to produce a pressure-sensitive adhesive sheet for a protective film includes adding a conventionally known radical generator and heating it, or adding a photosensitizer and irradiating it with ultraviolet rays. However, for the purpose of the present invention, the most suitable method is to irradiate the material with ionizing radiation, particularly electron beams generated by an electron beam accelerator. Note that the irradiation atmosphere may be in air, but is preferably in an inert gas. In addition, the energy of the electron beam does not need to be particularly limited, but the accelerating voltage is 150 KeV or more due to the resin thickness or manufacturing speed in manufacturing the protective adhesive sheet.
Something around 500 KeV is efficient. When the liquid resin composition of the present invention is cured to form a pressure-sensitive adhesive sheet, various materials such as plastic film, paper, and cloth can be used as the support depending on the purpose. In the conventional method, when polyethylene or polypropylene film is used as a support,
It is common practice to perform corona discharge treatment or apply a surface treatment agent to improve adhesion to the resin.
In the case of the present invention, such pretreatment is not necessarily required. This is also one of the features of the present invention. Further, as a method for applying the liquid resin composition of the present invention to these supports, a conventional method for applying a solvent-based resin can be directly adopted. The protective adhesive sheet obtained from the unsaturated polyester resin composition of the present invention by the method described above maintains good flexibility and has excellent long-term protection performance for decorative plywood. In order to explain the present invention in more detail, Examples and Comparative Examples are shown below, but the content of the present invention is not limited to the Examples. Example 1 Fumaric acid 4 was added to 1 four-necked separable flask.
mol, 6 mol of sepacic acid, 11 mol of 2,2,4-trimethylpentane 1,3-diol,
Condensation was carried out under stirring in a nitrogen gas atmosphere for 1.5 hours (maximum temperature: about 220°C) to obtain unsaturated polyester A with an acid value of 28. The average molecular weight of this unsaturated polyester A was 3100 (as determined by gel permeation chromatography using polystyrene as a standard sample). Next, resins were prepared by dissolving 0.3 moles of various monomers in 100 g of this unsaturated polyester A. These resins were applied onto a 40 μm thick polyethylene film using an applicator at a coating amount of 10 g/m ² . Each sample was irradiated with a 300 KeV electron beam generated from a transformer rectified accelerator in a nitrogen stream using a conveyor method to cure it. Table 1 shows the results of measuring the protection performance of the cured sheet. The protection performance was evaluated by cutting test pieces of the cured sheet into 10cm/5cm dimensions and attaching them to plain glass at 23°C and 65%.
After standing in an RH environment for 7 days, the sample piece was peeled off, and the resistance to peeling and the glass surface were visually observed.

[Table] As is clear from the results in Table 1, even when using styrene and methyl methacrylate, which are commonly used for unsaturated polyester resins, not only the adhesive strength is low but also the resin migrates to the glass surface, resulting in poor protection performance. It is. Furthermore, when n-butyl acrylate or 2-ethylhexyl acrylate is used, although it has viscosity, the resin still remains on the glass surface, making it unsuitable as a protective adhesive. On the other hand, the nitrogen atom-containing heterocyclic vinyl monomer of the present invention,
That is, by blending N-vinylpyridine and N-vinylpyrrolidone, a pressure-sensitive adhesive sheet with good peel resistance and protection performance from the glass surface condition can be obtained. Examples 2 to 5, Comparative Examples 1 to 3 Unsaturated polyesters B, C, D, and E were prepared in the same manner as in Example 1 using the combinations of dibasic acids and polyhydric alcohols shown in Table 2 (numbers are in moles). , F, G, and H were obtained. 0.5 mol of N-vinylpyrrolidone was mixed and dissolved in 100 g of each of these unsaturated polyesters, and samples were prepared and irradiated with electron beams in the same manner as in Example 1 to evaluate the protection performance of the cured sheet. The results are shown in Table 3. In the table, normal physical properties are when the specimen is stored in an environmental chamber at 23°C and 60% RH for a specified period of time, and accelerated physical properties are when the specimen is stored at 45°C and 80% RH.
Immediately after storing the specimen for a specified period in the RH environmental chamber.
Each sample was measured after being moved to an environment of 23°C and 60% RH and left for 5 hours.

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[Table] Adherent: Acrylic plate Peeling resistance: 180° peel test speed 30cm/〓
From the results in Table 3, it can be seen that the pressure-sensitive adhesive sheets of Examples 2-5, which correspond to the compositions of the present invention, have excellent protection properties in both normal and accelerated physical properties, but Comparative Example 1 (unsaturated polyester with carbon branched Comparative Example 2 (when the amount of aliphatic unsaturated polybasic acid is small), Comparative Example 3 (when aromatic polybasic acid is used without using aliphatic saturated polybasic acid) In both cases, cloudiness and residual resin were observed, making the sheet unsuitable for use as a protective adhesive sheet. Examples 6 to 8, Comparative Examples 4 and 5 A resin liquid having the composition shown in Table 4 was prepared for the unsaturated polyester D shown in Table 2, and samples were prepared and electron beam irradiated in the same manner as in Example 1. The protection performance (normal condition for 7 days) of the cured product was measured in the same manner as in Example 2. The results are shown in Table 5. Table 5
As is clear from the above, the pressure-sensitive adhesive sheets of Examples 6 to 8, which correspond to the compositions of the present invention, exhibited excellent protection performance for all of glass plates, acrylic plates, and aluminum plates. On the other hand, in both Comparative Example 4 (when the amount of added monomer is too large) and Comparative Example 5 (when the amount of added monomer other than the heterocyclic vinyl monomer is large), the resin transfers to the surface of the protected object. was observed, and the protection performance was poor.

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[Table] Volume parts

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Claims (1)

[Scope of Claims] 1. A protective film or adhesive for a protective film containing an unsaturated polyester resin composition mainly consisting of an unsaturated polyester produced from a specific acid component and a specific alcohol component and a specific vinyl monomer. In this case, the unsaturated polyester contains (i) an aliphatic unsaturated polybasic acid having 4 or more carbon atoms in an amount of 20 to 80 mol% of the acid component and an aliphatic saturated polybasic acid having 4 or more carbon atoms or an alicyclic aliphatic acid; At least one polybasic acid of the formula 80 as an acid component
(ii) a polyhydric alcohol having at least one carbon branch in the alcohol component;
The vinyl monomer contains at least one type of 5- or 6-membered heterocycle containing 1 or 2 nitrogen atoms as a substituent, and A protective film or a pressure-sensitive adhesive for a protective film, characterized in that a vinyl monomer is used in an amount of 0.1 to 15 moles per unsaturated bond contained in an unsaturated polyester. 2. The film or adhesive according to claim 1, wherein the vinyl monomer is used in an amount of 0.2 to 10 moles based on the unsaturated bonds contained in the unsaturated polyester. 3. The film or adhesive according to claim 1, wherein the unsaturated polyester has a molecular weight in the range of 1,000 to 10,000. 4 General formula (Here, R ₁ is H or CH ₃ ; R ₂ is an alkyl group having 2 to 13 carbon atoms) in an effective amount of 30 parts by weight or less of the total monomer amount. The film or adhesive according to claim 1.