JP5879110B2 - Adhesive composition and surface protective film - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition and a surface protective film.

  Conventionally, surface protection in which an adhesive layer is laminated on one side of a film-like substrate to protect the surface of various members such as optical devices, metal plates, painted metal plates, resin plates, glass plates, etc. Films (generally called protective tapes, masking tapes, or surface protective sheets) are widely used. In particular, surface protective films have recently been used for optical members for liquid crystal displays. Some optical members have an uneven surface, such as a prism sheet or a diffusion film. In order not to damage the irregularities, the surface (especially the outer surface of the irregularities) is protected by a surface protective film before use, and a surface protective film is applied to the irregular surface. When attaching, since a large contact area cannot be obtained, it is necessary to form an adhesive layer having a strong adhesive force.

As a sheet-like optical member, that is, a material for the optical sheet, polar polymers such as acrylic resins and polycarbonate resins are frequently used. The optical sheet is shipped to the optical device manufacturer after the surface protective film is attached, but may be exposed to a high temperature during transportation or storage.
Here, particularly when the surface of the adherend has an uneven shape, an increase in adhesive force due to an increase in the contact area between the adherend and the adhesive layer due to external factors such as time and temperature, so-called There is a problem of adhesive progress.
In particular, in the case of an adherend having relatively small irregularities such as a diffusion film, the increase in the contact area is remarkable, and the adhesion progress is particularly problematic.

  In general, acrylic pressure-sensitive adhesives are widely used as pressure-sensitive adhesives in the pressure-sensitive adhesive layer of the surface protective film, but acrylic pressure-sensitive adhesives have a particularly large increase in adhesive strength over time.

For the problem of increasing the adhesive strength, for example, a method for producing a surface protective film having an adhesive layer containing polyethyleneimine into which a higher alkyl group has been introduced has been proposed (Patent Document 1).
A surface protective film having a pressure-sensitive adhesive layer containing a polyethyleneimine having a higher alkyl group introduced therein and a phosphate ester surfactant has been proposed (Patent Document 2).
Furthermore, a surface protective film having an adhesive layer containing at least one kind of fatty acid amide and polyethyleneimine alkylcarbamide has been proposed (Patent Document 3).

Japanese Patent Laid-Open No. 1-129085 JP-A-6-1958 Japanese Patent Laid-Open No. 8-12952

However, according to the study by the present inventors, the above-described prior art still has the following problems.
In the case of the surface protective films of Patent Documents 1 and 2, in an optical sheet formed from a polar polymer such as an acrylic resin and a polycarbonate resin, the adhesion layer may be promoted by heating after application.
In the case of the surface protective film of Patent Document 3, depending on the type of fatty acid amide to be used, the adhesion layer may be promoted by heating after application.

  Therefore, the object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to promote adhesion even when exposed to a high temperature environment (for example, under the conditions of 40 to 60 ° C., or more than 60 ° C. and 80 ° C.). It is providing the adhesive composition which enables manufacture of the surface protection film which is suppressed, and such a surface protection film.

  As a result of intensive studies, the present inventors have formulated a suitable amount of a fatty acid amide compound having a specific endothermic peak or a fatty acid amide composition containing it as a main component in the pressure-sensitive adhesive layer of the surface protective film. It has been found that a surface protective film with suppressed adhesion progress can be obtained even when exposed to a high temperature environment (for example, under conditions of 60 to 80 ° C.), and as a result of further studies, the present invention has been completed. .

The pressure-sensitive adhesive composition of the present invention comprises a polymer (i): the following polymer block A and the following polymer block B, and a general formula [AB] n (wherein A represents the polymer block A, B Represents a polymer block B, n represents an integer of 1 to 3) and a copolymer (I) having a structure represented by the following:
Polymer (ii): Including the following polymer block A and the following polymer block B, the general formula A-B-A (the symbols in the formula are as defined above) or the general formula [A-B] x A copolymer (II) having a structure represented by -Y (wherein x represents an integer of 1 or more, Y represents a coupling agent residue, and other symbols are as defined above) or With its hydrogenated product;
The range of less than 25 ° C. or higher 40 ° C. by differential scanning calorimetry, has an endothermic peak of the fatty acid amide composition caused comprising a saturated fatty acid bis-amide compound or a main component thereof having a carbon number of 7 to 9, 7 to 9 carbon atoms saturated fatty acid bis-amide compound, or it contains a fatty acid amide composition comprising as a main component,
The overall aromatic alkenyl compound unit content (St (A + B)) of the polymer (i) and the polymer (ii) is 30 to 50% by weight,
The weight ratio (A: B) of the total amount of polymer block A and the total amount of polymer block B contained in the polymer (i) and the polymer (ii) is in the range of 5:95 to 25:75. And
The content of saturated fatty acid bis-amide compound of the carbon atoms 7-9 is possible, based on the total weight 100 parts by weight of the polymer (i) and the polymer (ii), is 0.3 to 2 parts by weight It is characterized by.
Polymer block A:
Polymer block having a series of aromatic alkenyl compound units and mainly consisting of aromatic alkenyl compound units Polymer block B:
An aromatic alkenyl-conjugated diene copolymer block containing a conjugated diene unit and an aromatic alkenyl compound unit at random, wherein the aromatic alkenyl compound unit content (St (b)) is 10 to 35% by weight. Combined block

Saturated fatty acid bis-amide compound of the carbon atoms 7-9 is preferably an ethylene Bisuka prill acid amide.
Furthermore, saturated fatty acid bis-amide compound resulting endothermic peak of the carbon atoms 7-9 is preferably in the range of 27 to 35 ° C..
Further, the endothermic amount of the endothermic peak is preferably not less than 0.5mJ respect fatty acid amide composition 1mg comprising a saturated fatty acid bis-amide compound or a main component thereof the carbon number of 7-9.

  The surface protective film of this invention has a base material layer and the adhesive layer which consists of the said adhesive composition, It is characterized by the above-mentioned.

  The surface protective film of the present invention is preferably a surface protective film for a diffusion film.

  By using the pressure-sensitive adhesive composition of the present invention, even when exposed to a high-temperature environment (for example, under conditions of 60 to 80 ° C.), a surface protective film in which the progress of pressure-sensitive adhesive is suppressed can be obtained. In the pressure-sensitive adhesive composition of the present invention and the surface protective film (particularly, a surface protective film for a diffusion film) containing the pressure-sensitive adhesive composition, for example, at 23 ° C. to 80 ° C., the pressure increase can be suppressed.

DSC (Differential Scanning Calorimetry) curve for the ethylene biscaprylic acid amide composition.

<Definition of symbols in this specification>
The symbol “˜” used to represent a numerical range in this specification is used with the intention that the numerical range includes the numerical values at both ends unless otherwise specified.

  In the present specification, the “content” of the repeating unit of the polymer used in the term “aromatic alkenyl compound unit content” or the like is obtained by converting the repeating unit into the weight of the monomer that is the origin of the repeating unit. Content, ie, the ratio of the weight of the monomer that is the origin of the repeating unit to the weight of all monomers to form the polymer (% by weight), ie, the aromatic alkenyl compound content of the polymer Means. Here, the “weight of all monomers for forming the polymer” approximates the weight of the polymer. Similarly, in the present specification, the “content” of the repeating unit of the polymer block is the content obtained by converting to the weight of the monomer that is the origin of the repeating unit, that is, the polymer block is formed. It means the ratio (% by weight) of the weight of the monomer that is the origin of the repeating unit to the weight of the total monomer. Here, the “weight of all monomers for forming the polymer block” is close to the weight of the polymer block.

  In the present specification, the “vinyl bond content” means the total content of 1,2-vinyl bonds and 3,4-vinyl bonds calculated by the Morero method using an infrared absorption spectrum method.

  In the present specification, the “fatty acid amide compound” means a pure fatty acid amide (for example, having a purity of 99% or more). The “fatty acid amide composition” means a composition containing a fatty acid amide compound, a diamine that is a raw material of the fatty acid amide compound, impurities such as fatty acids, and the like.

[Adhesive composition]
The pressure-sensitive adhesive composition of the present invention contains the following polymer (i), the following polymer (ii), and a predetermined at least one fatty acid amide compound or a fatty acid amide composition containing the same as a main component.

<Polymer (i) and Polymer (ii)>
In the present specification, the “polymer (i)” includes the following polymer block A and the following polymer block B, and is represented by the general formula [AB] n (wherein A represents the polymer block A, B represents The polymer block B is a copolymer (I) having a structure represented by n represents an integer of 1 to 3) or a hydrogenated product thereof.
In the present specification, the “polymer (ii)” includes the following polymer block A and the following polymer block B, and is represented by the general formula A-B-A (the symbols in the formula are as defined above) or General formula [AB] xY (wherein x represents an integer of 2 or more, Y represents a coupling agent residue, and other symbols have the same meanings as described above).
Or a hydrogenated product thereof.
In the present specification, a composition comprising the polymer (i) and the polymer (ii) may be simply referred to as a “copolymer composition”.
In the pressure-sensitive adhesive composition of the present invention, the total aromatic alkenyl compound unit content of the polymer (i) and the polymer (ii) is 30 to 50% by weight,
The weight ratio of the total amount of the polymer block A and the total amount of the polymer block B contained in the polymer (i) and the polymer (ii) is in the range of 5:95 to 25:75.
In the present specification, the “polymer block A” is a polymer block in which aromatic alkenyl compound units are continuous and mainly composed of aromatic alkenyl compound units.
In the present specification, the “polymer block B” is an aromatic alkenyl-conjugated diene copolymer block in which a conjugated diene unit and an aromatic alkenyl compound unit are randomly included, and the aromatic alkenyl compound unit content (St (B)) is a polymer block of 10 to 35% by weight.

<Polymer block A>
As described above, the “polymer block A” is a polymer block in which aromatic alkenyl compound units are continuous and mainly composed of aromatic alkenyl compound units.

  The “aromatic alkenyl compound unit” is a repeating unit derived from an aromatic alkenyl compound. Examples of the “aromatic alkenyl compound” include styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, vinylnaphthalene, vinylanthracene, N , N-Jetyl-p-aminoethylstyrene, vinylpyridine and the like. Among them, the “aromatic alkenyl compound unit” is preferably a styrene unit because the raw materials are easily industrially available.

  “Polymer block A” is composed of an aromatic alkenyl compound unit as a main repeating unit. Specifically, the aromatic alkenyl compound unit content is 80% by weight or more. By making the aromatic alkenyl compound unit content as high as 80% by weight or more, there is an advantage that the thermoplasticity of the pressure-sensitive adhesive composition can be improved and recycling of the pressure-sensitive adhesive composition becomes easier. The repeating unit other than the aromatic alkenyl compound unit that may be contained in an amount of less than 20% by weight includes a repeating unit derived from a compound copolymerizable with the aromatic alkenyl compound, such as a conjugated diene compound or (meth). Mention may be made of repeating units derived from acrylic ester compounds. Of these, 1,3-butadiene and isoprene are preferred because of their high copolymerizability with aromatic alkenyl compounds.

<Polymer block B>
“Polymer block B” is an aromatic alkenyl-conjugated diene copolymer block in which a conjugated diene unit and an aromatic alkenyl compound unit are randomly included, and has an aromatic alkenyl compound unit content (St (b)). It is a polymer block which is 10 to 35% by weight.

  The “conjugated diene compound unit” constituting the “polymer block B” is a repeating unit derived from a conjugated diene compound. Examples of the “conjugated diene compound” include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-octadiene, 1,3- Examples include hexadiene, 1,3-cyclohexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, myrcene, and chloroprene. Among them, the “conjugated diene compound unit” is at least one repeating unit selected from the group of 1,3-butadiene units and isoprene units because of high polymerization reactivity and easy availability of raw materials industrially. It is preferable.

  The “polymer block B” is composed of a conjugated diene compound unit as a main repeating unit. The conjugated diene compound unit content is preferably in the range of 65 to 90% by weight.

The “polymer block B” preferably has an aromatic alkenyl compound unit content (St (b)) in the range of 10 to 35% by weight, and in the range of 13 to 33% by weight. More preferably, it is still more preferably in the range of 16 to 30% by weight. When the aromatic alkenyl compound unit content is less than 10% by weight, the developability is heavy and the handling property may be deteriorated. On the other hand, when it exceeds 35% by weight, the flexibility of the pressure-sensitive adhesive composition is inferior, and sufficient adhesive force important for the surface protective film may not be ensured.
The “polymer block B” may also contain a repeating unit other than the conjugated diene compound unit and the aromatic alkenyl compound unit as long as the effects of the present invention are not hindered.

  Further, the “polymer block B” preferably has a vinyl bond content in the range of 50 to 90%, more preferably in the range of 60 to 80%. Moreover, there exists an advantage that the adhesive composition excellent in the balance of tack | tuck and adhesive force can be comprised by making a vinyl bond content rate into 50% or more.

<Copolymer (I)>
The “copolymer (I)” includes the following polymer block A and the following polymer block B, and is represented by the general formula [AB] n (wherein A is the polymer block A and B is the polymer block B). , N represents an integer of 1 to 3.).

  As “n” represents an integer of 1 to 3, as is clear, examples of the “structure represented by the formula [A-B] n” include AB, ABAB, And a structure represented by A-B-A-B-A-B. In these block copolymers, A and B may be the same or different in repetition.

  In the structure represented by [A-B] n, it is preferable that the terminal polymer block B occupies 2% by weight or more of the entire copolymer from the viewpoint of reliably exhibiting the effect of the polymer block B. Even when the terminal of some of the copolymers (I) has a structure of -A, the content of the terminal polymer block A is less than 2% by weight of the entire copolymer (I). Can exhibit the same effect as the terminal being the polymer block B. That is, it can be considered that the terminal of the above structure is the polymer block B substantially.

  n needs to be an integer of 1 to 3. Industrial productivity becomes favorable by making n into this range. In addition, from the viewpoint of improving adhesive strength and material strength, n is more preferably 1 to 2, and particularly preferably 1. That is, as the “copolymer having a structure represented by the general formula [AB] n”, a block copolymer having a structure represented by the general formula AB is particularly preferable.

  The copolymer (I) or its hydrogenated product (polymer (i)) preferably has an aromatic alkenyl compound unit content in the range of 30 to 50% by weight, and is preferably 33 to 45% by weight. More preferred. By setting the aromatic alkenyl compound unit content in this range, the pressure-sensitive adhesive composition has an appropriate holding power and an appropriate followability to the unevenness of the adherend surface, and has an excellent developability of the wound body. It becomes possible to compose things.

  The molecular weight of the polymer (i) is not particularly limited, but the weight average molecular weight is preferably 30,000 to 500,000, more preferably 80,000 to 300,000, and 100,000 to 200,000. Is particularly preferred. By setting the weight average molecular weight in the range of 30,000 to 500,000, the polymer (i), and thus the polymer (i) and the copolymer (II) or a hydrogenated product thereof (polymer (ii)) are formed. Industrial production of the copolymer composition can be facilitated. When the weight average molecular weight is less than 30,000, the polymer adheres to the production equipment or the like in the step of removing the solvent and drying the polymer, and industrial production of the polymer (i) may be difficult. On the other hand, when the weight average molecular weight is more than 500,000, the solubility in a solvent and the heat melting property are deteriorated, and it may be difficult to process the pressure-sensitive adhesive body.

Since the hydrogenated copolymer (I) has excellent heat resistance and weather resistance, the double bond derived from the conjugated diene monomer is 80% or more, preferably 90% or more, more preferably 95%. As described above, a hydrogenated product in which an unsaturated bond is hydrogenated to a saturated bond by hydrogenation is preferable.
In the present specification, the hydrogenation ratio (hydrogenation rate) means a hydrogenation rate calculated from a 270 MHz, ¹ H-NMR spectrum using carbon tetrachloride as a solvent.
The polymer (i) may be a single type (one type) or a combination of two or more types.

<Copolymer (II)>
The “copolymer (II)” includes the following polymer block A and the following polymer block B, and is represented by the general formula ABA (the symbols in the formula are as defined above) or the general formula [A -B] a copolymer having a structure represented by xY (wherein x represents an integer of 2 or more, Y represents a coupling agent residue, and other symbols are as defined above). It is.

As is clear from the above general formula, the copolymer (II) has a polymer block A at all molecular terminals.
The terminal polymer block A preferably accounts for 2% by weight or more of the entire copolymer (II). This is to ensure that the effect of the polymer block A is exhibited. Even if the terminal of some of the copolymers (II) has a structure of -B, the content of the terminal polymer block B is less than 2% by weight of the entire copolymer (II). Can exhibit the same effect as that of the polymer block A at the end. That is, it can be considered that the terminal of the above structure is the polymer block A substantially.
A structure represented by the general formula [AB] xY (wherein x represents an integer of 2 or more, Y represents a coupling agent residue, and other symbols have the same meanings as described above). In other words, the copolymer having has a structure in which the copolymer (I) is coupled by Y. Therefore, in the case of [A-B] x-Y, the mixture of (I) and (II) can be synthesized in the same reaction kettle. Therefore, from the industrial viewpoint, [A-B] x-Y Is preferred. When x is 3 or more, the copolymer is a so-called star polymer. x is preferably 2 to 4 from the viewpoint of suppressing side reactions during the production of the copolymer and controlling the physical properties of the copolymer.

  The copolymer (II) or its hydrogenated product (polymer (ii)) also has an aromatic alkenyl compound unit content in the range of 30 to 50 weights for the same reason as the polymer (i). Is preferable, and it is more preferable that it is 33 to 45 weight%.

  Since the polymer (ii) has excellent heat resistance and weather resistance, the double bond derived from the conjugated diene monomer is 80% or more, preferably 90% or more, more preferably 95% or more. It is preferable that the unsaturated bond is a hydrogenated product obtained by hydrogenating the saturated bond.

The molecular weight of the polymer (ii) is not particularly limited, but the weight average molecular weight is preferably 50,000 to 500,000, and more preferably 50,000 to 300,000. By making the weight average molecular weight in the range of 50,000 to 500,000, industrial production of the polymer (ii), and thus the copolymer composition comprising the polymer (i) and the polymer (ii) can be facilitated. Can be. When the weight average molecular weight is less than 50,000, the polymer adheres to the production equipment in the step of removing the solvent and drying the polymer, making it difficult to industrially produce the copolymer (II) or its hydrogenated product. There is a case. On the other hand, when the weight average molecular weight is more than 500,000, the solubility in a solvent and the heat melting property are deteriorated, and it may be difficult to process the pressure-sensitive adhesive body.
The polymer (ii) may be a single type (one type) or a combination of two or more types.

In the pressure-sensitive adhesive composition of the present invention, the weight ratio of the polymer (i) and the polymer (ii) is preferably in the range of 90:10 to 10:90. By including 10 parts by weight or more of polymer (i) in 100 parts by weight of the total amount of polymer (i) and polymer (ii), the pressure-sensitive adhesive layer is lifted from the surface of the adherend, and the film is peeled off. It is possible to exert a preferable effect that it is possible to effectively prevent problems (floating) that occur. On the other hand, by including 10 parts by weight or more of the polymer (ii) in 100 parts by weight of the total amount of the polymer (i) and the polymer (ii), the film is peeled off from the surface of the adherend. It is possible to exert a preferable effect that it is possible to effectively prevent a problem (glue residue) that the adhesive remains on the surface of the adherend and contaminates the surface of the adherend.
From the viewpoint of more reliably preventing the pressure-sensitive adhesive layer from floating and adhesive residue, the weight ratio of the polymer (i) to the polymer (ii) is more preferably in the range of 50:50 to 15:85. .

  From the viewpoint of achieving the effect of the present invention, the weight ratio of the total amount of the polymer block A and the total amount of the polymer block B contained in the polymer (i) and the polymer (ii) is 5:95 to 25:75. It is necessary to be within the range. In addition, by containing 5 parts by weight or more of the polymer block A in 100 parts by weight of the total amount of the polymer block A and the polymer block B, it is possible to impart an appropriate holding force to the formed pressure-sensitive adhesive layer. The preferable effect of becoming can be exhibited. On the other hand, by including 75 parts by weight or more of the polymer block B in 100 parts by weight of the total amount of the polymer block A and the polymer block B, the pressure-sensitive adhesive layer to be formed is good against unevenness on the surface of the adherend. Therefore, it is possible to exert a preferable effect that the surface of the adherend can be surely protected. The weight ratio of the total amount of the polymer block A and the total amount of the polymer block B is more preferably within the range of 7:93 to 23:77, and particularly preferably within the range of 10:90 to 21:79. preferable.

<Fatty acid amide compound or fatty acid amide composition containing it as a main component>
The pressure-sensitive adhesive composition of the present invention is a fatty acid amide in which an endothermic peak due to a fatty acid amide compound or a fatty acid amide composition containing it as a main component is measured in a range of 25 ° C. or higher and lower than 40 ° C. by differential scanning calorimetry. A compound or a fatty acid amide composition containing the compound as a main component is contained. In the present specification, the “fatty acid amide compound or a fatty acid amide composition containing the fatty acid amide compound as a main component” may be simply referred to as “fatty acid amide”.

  In the fatty acid amide composition containing a fatty acid amide compound as a main component, “comprising as a main component” means that the fatty acid amide compound is contained in an amount of 60% by weight or more. In addition, it is preferable to contain 80 weight% or more, and it is more preferable to contain 90 weight% or more. The fatty acid amide compound contained as a main component in the fatty acid amide composition may be a mixture of two or more fatty acid amide compounds. In this case, the content of the fatty acid amide compound as the main component is calculated by adding the contents of two or more fatty acid amide compounds.

<Endothermic peak due to fatty acid amide compound or fatty acid amide composition containing it as a main component>
At least one fatty acid amide compound contained in the pressure-sensitive adhesive composition of the present invention or a fatty acid amide composition containing the fatty acid amide compound as a main component is in the range of 25 ° C. or more and less than 40 ° C. by differential scanning calorimetry. Or an endothermic peak attributed to a “fatty acid amide composition containing it as a main component”. Here, the “endothermic peak derived from a fatty acid amide compound or a fatty acid amide composition containing it as a main component” is obtained by differential scanning calorimetry described later for the fatty acid amide compound or a fatty acid amide composition containing it as a main component. Refers to the endothermic peak.

  This endothermic peak is considered to be a sharp single peak for a pure single fatty acid amide compound. On the other hand, in the fatty acid amide composition containing diamine as a raw material and fatty acid as impurities, these endothermic peaks tend to become broad due to these impurities, and tend to become broader as the amount of impurities increases. . This endothermic peak also tends to be broad in the case of a mixture of two or more fatty acid compounds.

  The “fatty acid amide compound or fatty acid amide composition containing it as a main component” contained in the pressure-sensitive adhesive composition of the present invention has an endothermic peak due to “fatty acid amide compound or fatty acid amide composition containing it as a main component”. It may be in the range of 25 ° C. or more and less than 40 ° C. It does not matter whether the endothermic peak is broad or sharp. Although the principle is unknown, an “adhesive progress suppression effect” can be obtained by the “fatty acid amide compound or a fatty acid amide composition containing it as a main component” in which an endothermic peak is observed in the above range.

  When the pressure-sensitive adhesive composition is used for a surface protective film, when the endothermic peak attributed to the fatty acid amide compound can be observed at less than 25 ° C., the initial adhesive force is remarkably lowered and cannot be used as a surface protective film. In addition, when the endothermic peak due to the fatty acid amide compound can be observed at 40 ° C. or higher, a sufficient adhesion progress suppressing effect cannot be obtained particularly when held at a temperature of about 80 ° C. for a long period (for example, 3 days).

  The results of differential scanning calorimetry of ethylenebiscaprylic acid amide are shown in FIG. The curve in FIG. 1 is a DSC curve obtained in the third stage when the after-mentioned first to third stages are executed in order as in the endothermic peak evaluation of the fatty acid amide composition in the following examples. According to FIG. 1, endothermic peaks appear around 31, 36, and 171 ° C.

  The fatty acid amide compound in the “fatty acid amide compound or a fatty acid amide composition containing it as a main component” used in the pressure-sensitive adhesive composition of the present invention is preferably a saturated fatty acid bisamide compound. Examples of the saturated fatty acid bisamide compound include ethylene biscaprylic acid amide, ethylene bis stearic acid amide (EBSA), methylene bis stearic acid amide, hexamethylene bis stearic acid amide, ethylene bis myristic acid amide, ethylene bis lauric acid amide, ethylene Biscapric acid amide, ethylene bispalmitic acid; and m-xylylene bis stearic acid amide, and saturated fatty acid aromatic bisamide compounds such as N, N′-distearylisophthalic acid amide. As the fatty acid amide compound, a saturated fatty acid aliphatic bisamide compound having 6 to 10 carbon atoms is preferable, and a saturated fatty acid aliphatic bisamide compound having 7 to 9 carbon atoms is more preferable.

  The saturated fatty acid bisamide compound is usually synthesized by a dehydration condensation reaction between a diamine and a saturated fatty acid. For this reason, as is clear from the above description, the obtained saturated fatty acid bisamide (reaction product) may contain diamine and saturated fatty acid as impurities. In this specification, this case is referred to as “saturated fatty acid bisamide composition”.

  The melting temperature of the low melting point crystal of the “fatty acid amide compound or fatty acid amide composition containing it as a main component” is affected by the number of carbon chains and the degree of saturation of the fatty acid used as a raw material. Therefore, by synthesizing a fatty acid amide using two or more types of fatty acids, the melting temperature of the low melting point crystal of the obtained fatty acid amide composition, that is, the peak position of the endothermic peak due to the fatty acid amide compound can be adjusted. Is possible. These saturated fatty acid bisamide compounds may be used alone or in combination of two or more.

<Total content of fatty acid amide compound>
The total content of the fatty acid amide compound is from 0.3 to 2 parts by weight based on 100 parts by weight of the total weight of the polymer (i) and the polymer (ii) (weight of the copolymer composition). The total content of the fatty acid amide compound indicates, for example, the total content of ethylene biscaprylic acid amide having 8 carbon atoms and a fatty acid amide compound having 6 carbon atoms. When the total content of the fatty acid amide compound is less than 0.3 parts by weight, the suppression of the adhesion progress phenomenon is not sufficient. On the other hand, when it exceeds 2 parts by weight, the initial adhesive force is remarkably reduced.

  The total content of the fatty acid amide compound in the pressure-sensitive adhesive composition can be measured, for example, by GPC (gel permeation chromatography). For example, Waters 2695 + RI waters 2414 + UV Waters 2487 as the device, the column is Shodex LF-804 Columns (6.0 mm × 15.0 mm), the mobile phase can be quantified by using THF, and the content can be measured by using a calibration curve. I can do it. The total content of the fatty acid amide compound is the fatty acid amide compound or the main component of the fatty acid amide compound blended with respect to 100 parts by weight of the total weight of the polymer (i) and the polymer (ii) (weight of the copolymer composition). It can be calculated from the amount of fatty acid amide composition contained as a component.

  Since the fatty acid amide composition contained in the pressure-sensitive adhesive composition of the present invention is usually produced from natural raw materials, it is relatively difficult to determine what fatty acid amide compound is contained in what proportion. May be accompanied. For this reason, it is useful to specify the endothermic amount of the endothermic peak due to the fatty acid amide compound existing in the range of 25 ° C. or more and less than 40 ° C. by differential scanning calorimetry of the fatty acid amide composition, or the acid value of the fatty acid amide composition. There is a case.

<Endotherm>
The endothermic amount of the endothermic peak is preferably 0.5 mJ or more, more preferably 0.8 to 4.0 mJ with respect to 1 mg of the fatty acid amide compound or the fatty acid amide composition containing it as a main component. . The endothermic amount per unit weight of the fatty acid amide composition corresponds to the amount of the fatty acid amide compound as an active ingredient contained in the raw material. For this reason, the higher the endotherm, the higher the concentration of the active ingredient (fatty acid amide compound) contained in the raw material (fatty acid amide composition), and the smaller the amount of raw material added to the adhesive composition, the lower the raw material cost. It can be suppressed.

<Acid value>
The acid value of the fatty acid amide compound or the fatty acid amide composition containing it as a main component is preferably 14 mgKOH / g or less, more preferably 8 mgKOH / g or less, and further preferably 5 mgKOH / g or less. When the acid value is in such a range, the adhesive strength stability of the surface protective film with the passage of time is improved. An index for measuring the content of fatty acid remaining as an impurity after synthesizing fatty acid amide is the acid value, and a high value indicates that more fatty acid is contained as a reaction residue. Although fatty acid depends on the length of the alkyl chain, it may be deposited on the surface of the pressure-sensitive adhesive over time, causing the adhesive strength of the surface protective film to become unstable. By suppressing the acid value within the above range, the adhesive strength stability of the surface protective film over time is improved.

<Other ingredients>
The pressure-sensitive adhesive composition of the present invention includes a tackifier, a styrenic block phase reinforcing agent, a softener, an antioxidant, a light stabilizer, an ultraviolet absorber, a filler, a pigment, an anti-adhesive agent, if necessary. You may contain well-known additives, such as an olefin resin, a silicone polymer, a liquid acrylic copolymer, and a phosphate ester compound suitably.

Examples of the tackifier include petroleum resins such as aliphatic copolymers, aromatic copolymers, aliphatic-aromatic copolymers and alicyclic copolymers, coumarone-indene resins, and terpenes. Resins, terpene-phenol resins, rosin resins such as polymerized rosin, (alkyl) phenol resins, xylene resins or hydrogenated products such as those generally used for pressure-sensitive adhesives can be used without particular limitation. . It is more preferable to use a tackifier having a softening point of 90 to 140 ° C. These tackifiers may be used alone or in combination of two or more. In order to improve the peelability and weather resistance, it is more preferable to use a hydrogenated type tackifier. Moreover, you may use the tackifier marketed as a blend with an olefin resin.
The tackifier in the present invention means a compound that is compatible with a rubber layer that is a conjugated diene system or a hydrogenated soft segment thereof in an aromatic alkenyl block copolymer and can control the adhesive force. .
“Compatible” means that the tan δ peak temperature of a blend obtained by blending a tackifier with the copolymer composition is different from the tan δ peak temperature of the copolymer composition. That means. In the present specification, “tan δ peak temperature” means a temperature at which tan δ is maximized.

  Softeners are usually effective in improving adhesive strength. Examples of the softener include low molecular weight diene polymer, polyisobutylene, hydrogenated polyisoprene, hydrogenated polybutadiene, castor oil, tall oil, natural oil, process oil such as paraffinic oil, naphthenic oil and aromatic oil, What is generally used for an adhesive, such as liquid polyisobutylene resin, polybutene, or hydrogenated products thereof, can be used without particular limitation. These softeners may be used alone or in combination of two or more.

The antioxidant is not particularly limited, and examples thereof include commonly used ones such as phenolic antioxidants such as monophenol, bisphenol, and polymeric phenol, sulfur antioxidants, phosphorus antioxidants, and the like. It is done.
Examples of the light stabilizer include hindered amine compounds.
The ultraviolet absorber is not particularly limited, and examples thereof include salicylic acid ultraviolet absorbers, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, and cyanoacrylate ultraviolet absorbers.

Examples of the filler include calcium carbonate, magnesium carbonate, silica, zinc oxide, and titanium oxide.
In addition to fatty acid amides, long-chain alkyl grafts of polyethyleneimine, soybean oil-modified alkyd resins (for example, “Araquid 251” manufactured by Arakawa Chemical Industries, Ltd.), tall oil-modified alkyd resins (For example, Arakawa Chemical Industries, Ltd., trade name "Arachid 6300" etc.) etc. are mentioned.
These additives may be used alone or in combination of two or more.

<Surface protection film>
The surface protective film of this invention has a base material layer and the adhesive layer which consists of an adhesive composition demonstrated above.
Preferably, the pressure-sensitive adhesive layer is disposed on one surface of the base material layer.
An intermediate layer may exist between the base material layer and the pressure-sensitive adhesive layer.

<Base material layer>
The base material layer is preferably a polyolefin base material layer. Examples of the “polyolefin” include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer. Examples thereof include a copolymer, an ethylene-methyl acrylate copolymer, an ethylene-n-butyl acrylate copolymer, and polypropylene (homopolymer, random copolymer, block copolymer). These can be used alone or in combination of two or more. The “polyolefin” may be a polyolefin having a substituent, and a resin other than the polyolefin may be added. Furthermore, the end material of the polyolefin base material layer and the end material of the surface protection film which were produced in the manufacturing process of the surface protection film may be added.
The base material layer may be a single layer or a layer having two or more multilayer structures having different compositions.
The thickness of the base material layer can be appropriately adjusted depending on the use of the surface protective film. Usually, it is suitable to set the thickness to about 10 to 100 μm.

<Adhesive layer>
As described above, the pressure-sensitive adhesive layer is composed of the pressure-sensitive adhesive composition described above.
Although the thickness in particular of an adhesive layer is not restrict | limited, For example, it is about 0.5-50 micrometers normally, Preferably it is 1-40 micrometers, More preferably, it is 2-30 micrometers.

<Manufacturing method>
In the pressure-sensitive adhesive composition of the present invention, for example, copolymer (I) and copolymer (II) are synthesized by block polymerization, blended at a predetermined mass ratio, and then hydrogenated as desired. , Copolymer (I) or a hydrogenated product thereof, and a mixture of copolymer (I) or the hydrogenated product thereof, and an additive to be blended if desired is mixed by a conventional method .

As the hydrogenation catalyst, a compound containing any one of Group Ib, IVb, Vb, VIb, VIIb, and Group VIII metals can be used. Examples thereof include compounds containing Ti, V, Co, Ni, Zr, Ru, Rh, Pd, Hf, Re, and Pt atoms, and more specifically, Ti, Zr, Hf, Co, Ni, Rh. And metallocene compounds such as Ru, and supported heterogeneous catalysts in which metals such as Pd, Ni, Pt, Rh, and Ru are supported on a support such as carbon, silica, alumina, diatomaceous earth, and basic activated carbon. it can.
Specific examples of the metallocene compounds include a Kaminsky catalyst having two ligands in which hydrogen on the cyclopentagenyl ring (Cp ring) or Cp ring is substituted with an alkyl group, and ansa. Examples thereof include a type metallocene catalyst, a non-crosslinked half metallocene catalyst, and a crosslinked half metallocene catalyst.

  Specific examples include JP-A-1-275605, JP-A-5-271326, JP-A-5-271325, JP-A-5-222115, JP-A-11-292924, and JP-A-11-292924. JP 2000-37632 A, JP 59-133203 A, JP 63-5401 A, JP 62-218403 A, JP 7-90017 A, JP 43-19960 A, Mention may be made of the catalysts described in JP-B 47-40473. These various catalysts may be used alone or in combination of two or more.

  Alternatively, when the copolymer (II) has a structure represented by the above general formula [AB] xY (wherein the symbols are as defined above), the pressure-sensitive adhesive of the present invention. The composition may be produced by the following method (coupling method). In the coupling method, copolymer (I) or a hydrogenated product thereof (polymer (i)) and copolymer (II) or a hydrogenated product thereof (polymer (ii)) can be synthesized in one pot. Therefore, the production process is simple, the production cost is low, and the ratio of the polymer (i) to the polymer (ii) can be controlled by the kind and amount of the coupling agent.

The coupling method includes a first step: a step of synthesizing a copolymer having the structure [AB] by block polymerization, and a second step: a part of the copolymer having the structure [AB]. a coupling agent Y-Z _x (where "Y" coupling agent residue, "Z" is a leaving group, "X" represents an integer of 2 or more.) the was coupled, {[a -B] a step of synthesizing a copolymer having a structure of _x- Y}, and obtaining a hydrogenated product, a third step: a copolymer having the structure of [AB] and the above Copolymer composition comprising copolymer (I) and copolymer (II) each hydrogenated by hydrogenation to a copolymer having the structure of {[AB] _x -Y} And obtaining a process.

  Examples of the “coupling agent” include methyldichlorosilane, dimethyldichlorosilane, methyltrichlorosilane, butyltrichlorosilane, tetrachlorosilane, dibromoethane, tetrachlorotin, butyltrichlorotin, tetrachlorogermanium, bis (trichlorosilyl) ethane. Halogen compounds such as epoxidized soybean oil; carbonyl compounds such as diethyl adipate, dimethyl adipate, dimethyl terephthalic acid and diethyl terephthalic acid; polyvinyl compounds such as divinylbenzene; polyisocyanates; . Of these, methyldichlorosilane, dimethyldichlorosilane, methyltrichlorosilane, and tetrachlorosilane are preferred because they are easily industrially available and have high reactivity.

  The surface protective film of the present invention is, for example, a method in which a base sheet (base layer) is produced by extrusion, and then a liquid obtained by melting or dissolving the pressure-sensitive adhesive composition is applied or sprayed on the base sheet, or The base material sheet obtained by the inflation method and the pressure-sensitive adhesive sheet can be bonded together, or the base material and the pressure-sensitive adhesive composition can be coextruded using a T die having a multilayer manifold. Especially, since the multilayer sheet | seat with which the base material layer and the adhesive layer contact | adhered is obtained, the method of manufacturing by coextrusion is preferable. A liquid obtained by melting or dissolving the pressure-sensitive adhesive composition of the present invention is also included in the pressure-sensitive adhesive composition of the present invention.

<Application>
The surface protective film of the present invention can be suitably used for a sheet-like adherend having a smooth surface, and an adherend having irregularities such as an optical plate, a prism sheet, and a diffusion film. Especially, it can use suitably for the surface protection of a diffusion film.
The surface protective film of the present invention can be particularly suitably used for adherends having small unevenness among adherends having unevenness. In such an adherend, adhesion progress is likely to be a problem, but if the surface protective film of the present invention is used, the adhesion progress is less likely to occur even under high temperature conditions.
Specifically, the surface protective film of the present invention can be suitably used for an adherend having a surface roughness Ra of 2 μm or less, and more preferably, an adherend having a surface roughness Ra of 0.5 μm or less. Can be used. However, it goes without saying that the surface protective film of the present invention can also be used for other adherends.
In the present specification, “surface roughness Ra” is “arithmetic average height” defined in JIS B0601: 2001.

  Although it does not specifically limit as a material which comprises a to-be-adhered body, Resin which has translucency, for example, acrylic resin, a polycarbonate, etc. are mentioned.

  Hereinafter, although the surface protection film of this invention is demonstrated in detail based on an Example, this invention is not limited to a following example.

(Synthesis Example 1) (Synthesis of copolymer composition)
(Polymer block A)
A nitrogen-substituted reaction vessel is charged with 500 parts by mass of degassed / dehydrated cyclohexane, 20 parts by mass of styrene and 5 parts by mass of tetrahydrofuran, and 0.13 parts by mass of n-butyllithium is added at a polymerization start temperature of 40 ° C. Then, temperature rising polymerization was performed.
(Polymer block B)
After the polymerization conversion rate of the polymer A reached approximately 100%, the reaction solution was cooled to 15 ° C., and then 70 parts by mass of 1,3-butadiene and 10 parts by mass of styrene were added, followed by further temperature rising polymerization. .

  After the polymerization conversion rate reached almost 100%, 0.06 parts by mass of methyldichlorosilane was added as a coupling agent to carry out a coupling reaction. After the coupling reaction was completed, it was left for 10 minutes while supplying hydrogen gas at a pressure of 0.4 MPa-Gauge. A partially extracted polymer had a vinyl content of 64%, a weight average molecular weight of about 110,000, and a coupling rate of 60%.

Thereafter, 0.03 parts by mass of diethylaluminum chloride and 0.06 parts by mass of bis (cyclopentadienyl) titanium furfuryloxychloride were added to the reaction vessel and stirred. The hydrogenation reaction was started at a hydrogen gas supply pressure of 0.7 MPa-Gauge and a reaction temperature of 80 ° C., and when the hydrogen absorption was completed, the reaction solution was returned to room temperature and normal pressure, and the polymer was removed from the reaction vessel. A copolymer composition comprising (i) and polymer (ii) was obtained. The properties of this copolymer composition are shown in Table 1.
In Table 1, “St (A + B)”, “St (B)”, “St (A)”, and “St (b)” represent numerical values defined as follows. In the definition, “total polymer” means the whole of the polymer (i) and the polymer (ii).

“St (A + B)” is the aromatic alkenyl compound unit content of the whole polymer, and means a numerical value represented by the following formula (1). This is equal to the sum of the following “St (B)” and the following “St (A)”.
Formula (1):
St (A + B) = (aromatic alkenyl compound unit weight in the whole polymer) /
(Total monomer unit weight in all polymers) x 100 (wt%)
“St (B)” means a numerical value represented by the following formula (2).
Formula (2):
St (B) = (aromatic alkenyl compound unit weight in all polymer blocks B) /
(Total monomer unit weight in all polymers) x 100 (wt%)
“St (A)” means a numerical value represented by the following formula (3).
Formula (3):
St (A) = (aromatic alkenyl compound unit weight in all polymer blocks A) /
(Total monomer unit weight in all polymers) x 100 (wt%)
“St (b)” is the aromatic alkenyl compound unit content of the polymer block B, and means a numerical value represented by the following formula (4).
Formula (4):
St (b) = (aromatic alkenyl compound unit weight in all polymer blocks B) /
(Total monomer unit weight in all polymer blocks B) × 100 (% by weight)
In Table 1, “A: B” represents a weight ratio between the total amount of the polymer block A and the total amount of the polymer block B.
In Table 1, “(i) :( ii)” represents the weight ratio of the polymer (i) to the polymer (ii).
Further, in Table 1, “conjugated diene content” represents the conjugated diene unit content of the polymer block B.
In Table 1, “Vinyl bond content” represents the vinyl bond content of the polymer block B.

(Examples 1-3, Comparative Examples 1-6)
To 100 parts by weight of the copolymer composition obtained in Synthesis Example 1, a tackifier (Arcon P100 (Arakawa Chemical Industries)), an antioxidant (Irganox 1010 (Ciba Specialty Chemicals)), And fatty acid amide was mix | blended as Table 2, and each adhesive composition was obtained. In addition, the description of the fatty acid amide in the following Table 2 means the fatty acid composition containing it as a main component, and contains diamine as a raw material, impurities such as fatty acid, and fatty acid diamide having different carbon numbers.
Moreover, the endothermic peak different from melting | fusing point by the differential scanning calorimetry of the used fatty acid amide composition was measured and evaluated as follows.

(Evaluation method of endothermic peak of fatty acid amide)
The first to third stages were sequentially executed by a differential scanning calorimeter (DSC 6220, manufactured by SII). The endothermic peak due to the fatty acid amide compound can be read from the DSC curve in the third stage. FIG. 1 shows a DSC curve in the third stage.
1st stage: It heats up from 20 degreeC to 200 degreeC with the temperature increase rate of 20 degree-C / min.
Second stage: The temperature is decreased from 200 ° C. to 20 ° C. at a temperature decreasing rate of 20 ° C./min.
3rd stage: It heats up from 20 degreeC to 200 degreeC with the temperature increase rate of 20 degree-C / min.

  Polypropylene (J715M manufactured by Prime Polymer Co., Ltd.) is used as the base material, and the base material and each pressure-sensitive adhesive composition are coextruded by the T-die method, so that the base material layer has a thickness of 34 μm and the pressure-sensitive adhesive layer has a thickness of 6 μm. And the surface protective films of Examples 1 to 3 and Comparative Examples 1 to 6 were laminated and integrated.

(Evaluation of surface protection film)
The following items were evaluated for each surface protective film obtained as described above.

(1) Initial adhesive strength Each surface protective film was affixed so that the lens surface of a diffusion film with Ra of 0.44 nm might be covered. As the diffusion film, an acrylic resin was prepared. Affixing conditions were as follows: a room temperature of 23 ° C. and a relative humidity of 50%, each using a 2 kg pressure-bonded rubber roller, affixed at a speed of 300 mm / min, left in that state for 30 minutes, and conformed to JIS Z0237. The 180 degree peel strength at 25 mm width was measured at a speed of 300 mm / min. The peel strength measured in this manner was taken as the initial adhesive strength.

(2) Adhesive strength with time Each surface protective film was used in an environment with a room temperature of 23 ° C. and a relative humidity of 50%, using a 2 kg pressure-bonded rubber roller on the surface of the diffusion film used in the initial adhesive strength evaluation of (1). Affixed at a speed of 300 mm / min. The diffusion film to which the surface protective film was attached was left for 3 days at 40 ° C., 60 ° C., and 80 ° C., respectively. These were taken out to room temperature and allowed to stand for 60 minutes, and then, according to JIS Z0237, 180 degree peel strength at 25 mm width was measured at a speed of 300 mm / min.
The peel strength measured in this manner was used as the adhesive strength with time, and the change rate of adhesive strength with time (adhesive force progress rate) was calculated from the initial adhesive strength by the following equation.
Adhesive strength progress rate = (Aging adhesive strength / Initial adhesive strength) × 100

The rate of progress of adhesive strength was determined according to the following criteria.
◎ (excellent): less than 400% ○ (good): 400% or more and 600% or less × (defect): more than 600%

(3) Comprehensive evaluation ○ (good): Adhesive strength increase rate after 3 days at 40 ° C., 60 ° C., 80 ° C. is not defective × (defect): 3 days at 40 ° C., 60 ° C., 80 ° C. One of the rate of increase in adhesive strength after time is poor. The results are shown in Table 2.

  As is apparent from Table 2, there is an endothermic peak in the range of 25 ° C. or more and less than 40 ° C., and the total content of the fatty acid amide compound used is the total weight of the polymer (i) and the polymer (ii). (Weight of copolymer composition) When it is 0.3 to 2 parts by weight with respect to 100 parts by weight, it is 3 hours under high temperature conditions (40 ° C, 60 ° C conditions, and further under 80 ° C conditions). Even when it was cured for more than a day), it showed the effect of suppressing the adhesion progress.

Claims (6)

Polymer (i): comprising the following polymer block A and the following polymer block B, the general formula [AB] n (wherein A is the polymer block A, B is the polymer block B, n is A copolymer (I) having a structure represented by the formula (1) or a hydrogenated product thereof:
Polymer (ii): Including the following polymer block A and the following polymer block B, the general formula A-B-A (the symbols in the formula are as defined above) or the general formula [A-B] x A copolymer (II) having a structure represented by -Y (wherein x represents an integer of 1 or more, Y represents a coupling agent residue, and other symbols are as defined above), With its hydrogenated product;
The range of less than 25 ° C. or higher 40 ° C. by differential scanning calorimetry, has an endothermic peak of the fatty acid amide composition caused comprising a saturated fatty acid bis-amide compound or a main component thereof having a carbon number of 7 to 9, 7 to 9 carbon atoms saturated fatty acid bis-amide compound, or it contains a fatty acid amide composition comprising as a main component,
The overall aromatic alkenyl compound unit content (St (A + B)) of the polymer (i) and the polymer (ii) is 30 to 50% by weight,
The weight ratio (A: B) of the total amount of the polymer block A and the total amount of the polymer block B contained in each of the polymer (i) and the polymer (ii) is in the range of 5:95 to 25:75. And
Total content of saturated fatty acid bis-amide compound of the 7-9 carbon atoms, wherein the total weight 100 parts by weight of the polymer (i) and the polymer (ii), is 0.3 to 2 parts by weight A pressure-sensitive adhesive composition.
Polymer block A:
Polymer block having a series of aromatic alkenyl compound units and mainly consisting of aromatic alkenyl compound units Polymer block B:
An aromatic alkenyl-conjugated diene copolymer block containing a conjugated diene unit and an aromatic alkenyl compound unit at random, wherein the aromatic alkenyl compound unit content (St (b)) is 10 to 35% by weight. Combined block Saturated fatty acid bis-amide compound of the 7-9 carbon atoms, an ethylene Bisuka prills acid amide, pressure-sensitive adhesive composition according to claim 1. Endothermic quantity of the endothermic peak is not less than 0.5mJ respect fatty acid amide composition 1mg comprising a saturated fatty acid bis-amide compound or a main component thereof of the 7-9 carbon atoms, according to claim 1 or 2 Adhesive composition. The acid value of the saturated fatty acid bis-amide compound having a carbon number of 7-9 or a fatty acid amide composition comprising it as a main component, 14 mg / g KOH or less, the pressure-sensitive adhesive according to any one of claims 1 to 3 Composition. A base material layer;
A pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to any one of claims 1 to 4 ,
A surface protective film. The surface protective film according to claim 5 , which is a surface protective film for a diffusion film.