KR20200050463A - Adhesive resin composition and protective film using the same - Google Patents

Abstract

An object of the present invention is to provide a pressure-sensitive adhesive composition that, when attached to an adherend having fine surface irregularities, has sufficient adhesion and is difficult to improve adhesion even when exposed to high temperatures during transport and storage.
In order to solve the above problems, the adhesive resin composition of the present invention has a block copolymer satisfying 1) and 2) below as a main component, and contains α-methylstyrene resin and terpene resin.
1) It is a block copolymer containing the following polymer block A and the following polymer block B, and having structural formula A-B-A and / or structural formula A-B.
Polymer block A: A polymer block composed mainly of units derived from aromatic alkenyl compound monomer units and mainly derived from aromatic alkenyl compound monomer units.
Polymer block B: Aromatic alkenyl monomer-conjugated diene monomer copolymer block containing randomly derived units derived from conjugated diene monomer units and aromatic alkenyl compound monomer units
2) The hydrogenation rate of the double bond derived from the conjugated diene monomer unit in the polymer block B is 90 mol% or more.

Description

Adhesive resin composition and protective film using the same

The present invention relates to a protective film having an adhesive composition and an adhesive layer made of the same. In detail, the protective film is stored in a roll state, and thereafter, when the film is drawn out, the film is not partially stretched or deformed, and the processability is excellent, and the adhesion and peelability to the adherend are also excellent. It is related with this excellent adhesive resin composition and the protective film which has the adhesive layer which consists of it.

Conventionally, the protective film is stored by stacking, transporting, or bending a member such as a prism sheet used for optical use, a synthetic resin plate used for construction materials, a stainless steel plate, an aluminum plate, a decorative plywood, a steel plate, and a glass plate. It has been used to protect against scratches during secondary processing such as processing and press processing. It has also been used to protect home appliances, precision machinery and automobile bodies from scratches when conveyed in the manufacturing process.

Such a protective film should have good adhesiveness and, at the same time, after use, must be able to be easily peeled off without contaminating the surface of the adherend with the adhesive.

The adherend has recently been diversified, and many of them are seen, from those with a smooth coating surface to those with surface irregularities.

Among them, the rear surface of the prism sheet is smooth compared to a prism surface having a large surface irregularity, but a rear surface having a fine surface irregularity is formed to uniformly diffuse the light of the backlight, and prevent interference due to close contact with other members, A function is provided to make it difficult to make visible problems such as scratches.

For this reason, in order to protect the back surface of the prism sheet with a protective film when piled up and stored or transported, the adhesive force with the back surface needs to be good.

However, when the time elapsed after affixing the protective film to the adherend, a problem called an increase in adhesion (so-called adhesion engine) occurs, and there is a problem that it is difficult to peel. It is known that this is because the product with the protective film attached becomes more prominent by being exposed to high temperatures during transportation and storage.

As a protective film used for adherends having fine surface irregularities, a polymer block composed mainly of aromatic alkenyl compound units, and a conjugated diene monomer unit and aromatics, in which aromatic alkenyl compound units, which are known to be relatively difficult to generate adhesive adhesion, are continuously formed It is known to use a copolymer composed of an aromatic alkenyl-conjugated diene monomer copolymer block randomly containing alkenyl compound units for an adhesive layer (for example, see Patent Document 1, etc.), which protects against adherend Was sufficient, but it was not compatible with the ease of peeling from an adherend and the ease of ejection of the protective film from the roll state.

Japanese Patent Publication No. 2014-16934

The object of the present invention is to store the protective film in a roll state, and when the film is then drawn out, the film is not partially stretched or deformed, and has excellent workability, and also has a fine surface, such as the back side of a prism sheet. When adhered to an adherend having irregularities, it has sufficient adhesion, and even when exposed to high temperatures during transportation and storage, adhesion is difficult to improve, and no looseness occurs on the adherend even after peeling the protective film. It is to maintain function.

The present invention is an adhesive resin composition containing a block copolymer satisfying the following 1) and 2) as a main component, and containing α-methylstyrene-based resin and terpene-based resin.

1) It is a block copolymer containing the following polymer block A and the following polymer block B, and having structural formula A-B-A and / or structural formula A-B.

Polymer block A: A polymer block composed mainly of units derived from an aromatic alkenyl compound monomer unit and mainly derived from aromatic alkenyl compound units.

Polymer block B: Aromatic alkenyl monomer-conjugated diene monomer copolymer block containing randomly derived units from conjugated diene monomer units and aromatic alkenyl compound monomer units

2) The hydrogenation rate of the double bond derived from the conjugated diene monomer unit in the polymer block B is 90 mol% or more.

In this case, it is very suitable that the conjugated diene monomer unit is a butadiene monomer unit.

Moreover, in this case, it is very suitable to contain 1 to 50 parts by weight of the α-methylstyrene resin relative to 100 parts by weight of the block copolymer.

Moreover, in this case, it is very suitable that the terpene-based resin contains a terpene phenol resin.

Moreover, in this case, it is very suitable to contain 0.1 to 30 parts by weight of terpene phenol resin with respect to 100 parts by weight of the block copolymer.

Moreover, in this case, it is very suitable to contain an organic lubricant.

Further, in this case, it is very suitable to contain 0.1 to 2 parts by weight of an organic lubricant relative to 100 parts by weight of the block copolymer.

Moreover, in this case, it is very suitable that the organic lubricant is ethylenebisstearic acid amide and / or calcium stearate.

A protective film having an adhesive layer made of the adhesive resin composition and a base layer made of a polypropylene resin composition is very suitable.

In this case, a protective film having a release layer on the opposite side from the adhesive layer is very suitable.

Also in this case, the protective film is very suitably used for protecting the back side of the prism sheet.

The adhesive resin composition of the present invention, the protective film is stored in a roll state, and when the film is then drawn out, the film is not partially stretched or deformed, has excellent workability, and is also provided on the back side of the prism sheet. As described above, when adhered to an adherend having fine surface irregularities, it has sufficient adhesion, and even when exposed to high temperatures during transportation and storage, the adhesion is difficult to improve, and after the protective film is peeled off, there is no looseness on the adherend It does not occur, and the function can be maintained.

(Block copolymer)

The block copolymer in the present invention is a block copolymer comprising the polymer block A below and the polymer block B below.

Polymer block A: A polymer block composed mainly of units derived from aromatic alkenyl compound monomer units and mainly derived from aromatic alkenyl compound monomer units.

Polymer block B: Aromatic alkenyl compound monomer-conjugated diene monomer copolymer block containing randomly derived units derived from a conjugated diene monomer unit and an aromatic alkenyl compound monomer unit

The block copolymer of the present invention is a block copolymer containing the above-mentioned polymer block A and polymer block B and having structural formulas A-B-A and / or A-B.

The block copolymer of the present invention has a polymer block B which is an aromatic alkenyl compound monomer-conjugated diene monomer copolymer block containing randomly derived units derived from a conjugated diene monomer unit and an aromatic alkenyl compound monomer unit, and other blocks Than the copolymer, the adhesive film is less likely to occur even when the protective film is attached to an adherend having fine surface irregularities and is exposed to high temperatures during transport and storage. Among them, a case where only the structural formulas A-B-A in which polymer blocks A are present at both ends is preferable because the adhesion engine at high temperature is more suppressed.

It is preferable that the content rate of the unit derived from the aromatic alkenyl compound monomer unit in a block copolymer is 30 weight% or more.

If the content ratio of the unit derived from the aromatic alkenyl compound monomer unit is 30% by weight or more, the initial adhesive strength is excessively strong, looseness occurs, or the adhesive strength is hard to be enhanced, more preferably 40% by weight or more, and 45% by weight % Or more is more preferred.

When the content ratio of the unit derived from the aromatic alkenyl compound monomer unit is 60% by weight or less, initial adhesion is easily obtained, and 55% by weight or less is more preferable.

The content rate (St (A + B)) of the unit derived from the aromatic alkenyl compound monomer in the block copolymer represents a numerical value defined by the following equation.

The content rate of the unit derived from such an aromatic alkenyl compound monomer unit is determined by 1H-NMR. In addition, the content rate of the unit derived from such an aromatic alkenyl compound monomer unit can be determined by an infrared spectrum method, and a value almost equal to 1H-NMR is obtained.

The block copolymer preferably has a weight average molecular weight of 30,000 to 200,000.

When the weight average molecular weight is 200,000 or less, adhesion to an adherend having fine surface irregularities is easily obtained, solubility in a solvent and heat melting properties are improved, and also film production by industrial processing into pellets or melt coextrusion It may be easier. It is more preferable that the weight average molecular weight of the block copolymer is 180,000 or less.

When the weight-average molecular weight is 30,000 or more, in the step of desolvating and drying the polymer, it is difficult to attach the polymer to manufacturing facilities, etc., and industrial production may be facilitated. The weight average molecular weight of the block copolymer is more preferably 100,000 or more, and more preferably 130,000 or more.

The melt mass flow index (MFR) value of the block copolymer is preferably in the range of 0.1 to 20 g / min, more preferably 1 to 15 g / min. By setting the melt mass flow index value in the range of 0.1 to 20 g / min, not only can industrial production of the block copolymer be facilitated, but also excellent workability can be provided during film formation. When the melt mass flow index value is less than 0.1 g / min, solubility in a solvent during polymerization is deteriorated, thermal meltability is lowered, and it may be difficult to take out the polymer from the manufacturing equipment. This difficulty becomes a problem that can be recurred even during film production. The melt mass flow index value is more preferably 2 g / min or more, and even more preferably 3 g / min or more.

On the other hand, if the melt mass flow index value is larger than 20 g / min, in the step of desolvating and drying the polymer, the polymer adheres to the inside of the manufacturing equipment and remains, making it difficult to take out the polymer. This difficulty becomes a problem that can be recurred even during film production. The melt mass flow index value is more preferably 10 g / min or less, and even more preferably 6 g / min or less.

(Polymer block A)

The polymer block A in the present invention is composed of a unit derived from an aromatic alkenyl compound monomer unit as a main repeating unit, and is mainly a polymer block composed of units derived from an aromatic alkenyl compound monomer unit. It is preferable that the content rate of the unit derived from the aromatic alkenyl compound monomer unit in this is 80 weight% or more.

The advantage that by setting the unit derived from the aromatic alkenyl compound monomer unit in the polymer block A to be 80% by weight or more, the thermoplasticity of the adhesive resin composition can be suppressed and the change in the adhesive strength of the adhesive resin composition becomes easier. There is this. The unit derived from the aromatic alkenyl compound monomer unit in the polymer block A is more preferably 90% by weight or more.

Moreover, the repeating unit other than the unit derived from an aromatic alkenyl compound monomer unit may be contained in the range of less than 20 weight%.

The aromatic alkenyl compound monomer unit is not particularly limited, for example, styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, and vinyl. And aromatic alkenyl monomer units such as naphthalene, vinyl anthracene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene and vinylpyridine.

Among the aromatic vinyl alkenyl monomer units, styrene units are preferred from the viewpoint of easy availability of raw materials.

The repeating unit other than the unit derived from the aromatic alkenyl compound monomer unit is a repeating unit derived from a compound copolymerizable with the unit derived from the aromatic alkenyl compound monomer unit, such as a conjugated diene compound or a (meth) acrylic acid ester compound. And repeating units derived therefrom. Among them, 1,3-butadiene and isoprene are preferred from the viewpoint of high copolymerizability with units derived from aromatic alkenyl compound units.

It is necessary that the content rate of the polymer block A in the block copolymer is 10% by weight or more. When the content rate of the polymer block A is less than 10% by weight, the initial adhesive strength may be too strong, resulting in looseness, or the adhesive strength may be easily enhanced. On the other hand, the content rate of the polymer block A in the block copolymer is preferably 50% by weight or less. If it exceeds 50% by weight, the initial adhesive strength may not be confirmed. It is more preferably 45% by weight or less, and even more preferably 40% by weight or less.

(Polymer block B)

The polymer block B in the present invention is an aromatic alkenyl monomer-conjugated diene monomer copolymer block randomly containing a unit derived from a conjugated diene monomer unit and a unit derived from an aromatic alkenyl compound monomer unit. By randomly containing the unit derived from the conjugated diene unit and the unit derived from the aromatic alkenyl compound unit, the protective film using the pressure-sensitive adhesive composition of the present invention is adhered to an adherend having fine surface irregularities, and during transport thereof, and Even when exposed to high temperatures during storage, adhesion engines are unlikely to occur.

Here, "random" is interpreted in a broad sense, and the chain distribution of the conjugated diene unit and the aromatic alkenyl compound unit is in a state in accordance with a certain statistical law obtained by simultaneously polymerizing the mixed conjugated diene and aromatic alkenyl compound. Means

The aromatic alkenyl compound monomer unit is not particularly limited, for example, styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, and vinyl. And aromatic vinyl monomer units such as naphthalene, vinyl anthracene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene and vinylpyridine.

Among the aromatic vinyl monomer units, styrene units are preferred from the viewpoint of easy availability of raw materials.

The conjugated diene monomer unit in the polymer block B in the present invention is not particularly limited, for example, 1,3-butadiene, 1,2-butadiene, isoprene, 2,3-dimethyl-butadiene, 1,3- Pentadiene, 2-methyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-cyclohexadiene, 4,5-diethyl-1,3- And diolefins such as octadiene, 3-butyl-1,3-octadiene, myrcene and chloroprene.

Among diolefins, it is preferable that they are one or more units selected from 1,3-butadiene units or isoprene units having high polymerization reactivity and easy availability of raw materials. Further, it is more preferable to select 1,3-butadiene units in order to obtain high mechanical strength.

The hydrogenation rate of the double bond derived from the conjugated diene monomer unit in the block copolymer B in the present invention is 90 mol% or more, and is necessary in view of heat resistance and weather resistance. It is preferably 95 mol% or more, and more preferably 98 mol% or more. If it is less than 90 mol%, not only adhesion to an adherend having fine irregularities is not obtained, but also heat resistance and weather resistance are concerned.

It is preferable that the content rate of the unit derived from the aromatic alkenyl compound monomer unit in block copolymer B is 10 weight% or more. When the content rate of the unit derived from the aromatic alkenyl compound monomer unit is less than 10% by weight, the initial adhesive strength may be too strong, looseness may occur, or the adhesive strength may be easily enhanced. The content rate of the unit derived from the aromatic alkenyl compound monomer unit is more preferably 20% by weight or more, and particularly preferably 30% by weight or more.

On the other hand, the content of the unit derived from the aromatic alkenyl compound monomer unit is preferably 80% by weight or less. When it exceeds 80% by weight, the initial adhesive strength may not be confirmed. The content rate of the unit derived from the aromatic alkenyl compound monomer unit is more preferably 50% by weight or less, and particularly preferably 40% by weight or more.

(α-methylstyrene resin)

As a result of careful examination, the α-methylstyrene-based resin, in combination with terpene resin, suppresses the adhesion engine of the pressure-sensitive adhesive layer, thereby improving the peelability of the surface of the base layer or the release layer surface and the pressure-sensitive adhesive layer opposite to the surface of the pressure-sensitive adhesive layer It has been found that it has an effect and can also obtain an initial adhesive strength sufficiently. This is presumed to be due to the diffusion of the α-methylstyrene resin into the polymer block B of the block copolymer. Simply increase the content of units derived from aromatic alkenyl compound monomers in the block copolymers having the structural formulas A-B-A and / or A-B and the content of the polymer block A in the block copolymer, or increase the molecular weight of the block copolymer. It is an effect that cannot be obtained by simply raising it.

As the α-methylstyrene-based resin used in the present invention, α-methylstyrene homopolymer and / or α-methylstyrene are used as main components, and styrene and p-methylstyrene, p-chlorostyrene, chloromethylstyrene, and tert- And copolymers composed of two or more styrene-based compounds such as butyl styrene, p-ethyl styrene, and divinylbenzene.

The α-methylstyrene resin may be a copolymer with an aliphatic monomer.

The molecular weight Mw is preferably 4000 or more from the viewpoint of the strength of the resin or bleed-out. In the case of a copolymer composed of two or more monomers, a block copolymer or a random copolymer may be used.

Especially, it is preferable that alpha-methylstyrene resin has a softening point of 100 degreeC or more, and 150 degreeC or more is more preferable. Specifically, manufactured by Eastman Chemical Co., Ltd., trade name "ENDEX155" (softening point 155 ° C, molecular weight Mz = 13850, Mw = 6950, Mn = 2400, Mw / Mn = 3.0, density = 1.04 g / ml, glass transition temperature = 99 ° C), "ENDEX160" (softening point 160 ° C), and the like.

(Terpene resin)

In the present invention, terpene-based resins or hydrogenated products thereof can be mentioned.

Terpene-based resins are obtained by cationic polymerization using terpene-based compounds (eg, α-pinene, β-pinene, limonene, etc.) collected from pine or orange skin.

When terpene-based resins are largely distinguished, polyterpene resins, which are polymers of terpene monomers, aromatic modified terpene resins obtained by copolymerizing terpene monomers and aromatic monomers, terpene phenol resins made by reacting terpene monomers with phenols, and further hydrogenating them The resulting hydrogenated terpene resin is classified.

In the case of the hydrogenated resin of the terpene-based resin, the fear of discoloration over time or over time (over time) can be reduced.

The terpene-based resins may be used alone or in combination of two or more. It is preferable to use a terpene-based resin having a glass transition temperature or a softening point of 30 ° C or higher. If it is 30 ° C or higher, there is little risk of exudation at room temperature, and handling is excellent. The glass transition temperature or softening point of the terpene-based resin is more preferably 50 ° C. or higher, more preferably 65 ° C. or higher, and particularly preferably 90 ° C. or higher, in consideration of high-temperature engine resistance.

The terpene-based resin can be expected to improve adhesion and suppression of anti-angularity due to the effect of plasticizing the adhesive resin composition and the effect of inhibiting the molecular motion of the adhesive resin by combining with α-methylstyrene.

Among the terpene-based resins, terpenephenol resins are preferred, and hydrogenated terpenephenol resins are particularly preferred. Since the phenol group of the terpene phenol resin has an electrical affinity with the adherend, its adhesive strength is hardly increased even when the product with the protective film is exposed to high temperatures during transport and storage, and stable high adhesive strength is expected. Since the terpene phenol resin has a high softening point and is about 130 ° C, it is possible to sufficiently exhibit the effect of suppressing the adhesion engine and the initial adhesion by combining with α-methylstyrene resin.

Also, in the case of terpene phenol resin, the possibility of discoloration over time or over time can be reduced by hydrogenation.

(Adhesive resin composition)

The adhesive resin composition of the present invention has the block copolymer described in the above (block copolymer) as a main component and contains α-methylstyrene resin and terpene resin. Here, the main component means that 50 wt% or more is contained in the adhesive resin composition.

At this time, it is preferable to contain 1 to 50 parts by weight of α-methylstyrene resin relative to 100 parts by weight of the block copolymer, more preferably 5 to 45 parts by weight, even more preferably 10 to 40 parts by weight, and 15 to 40 parts by weight Particularly preferred. If the α-methylstyrene resin is 1 part by weight or more with respect to 100 parts by weight of the block copolymer, the adhesion engine of the block copolymer is easily suppressed, and if it is 50 parts by weight or less, the adhesive strength with the adherend is less likely to decrease. When the α-methylstyrene-based resin is 10 parts by weight or more with respect to 100 parts by weight of the block copolymer, the adhesion engine of the block copolymer is more likely to be suppressed, and if it is 40 parts by weight or less, the adhesion with the adherend is less likely to decrease.

In addition, it is preferable to contain 1 to 50 parts by weight of terpene-based resin with respect to 100 parts by weight of the block copolymer. When the content of the terpene-based resin is 1 part by weight or more, an improvement in initial adhesive strength is seen. It is more preferably 3 parts by weight or more, still more preferably 5 parts by weight or more, and particularly preferably 15 parts by weight or less.

When the content of the terpene-based resin is 50 parts by weight or less, compatibility with the adhesive resin composition is not lowered, and it is difficult to see a decrease in initial adhesive strength. It is more preferably 40 parts by weight or less, still more preferably 30 parts by weight or less, and particularly preferably 25 parts by weight or less.

The adhesive resin composition of the present invention, in addition to the above-mentioned block copolymer, α-methylstyrene-based resin and terpene-based resin, if necessary, organic lubricants, antioxidants, light stabilizers, ultraviolet absorbers, fillers, pigments, styrenic block-like reinforcement You may suitably contain well-known additives, such as a softener, an adhesion prevention agent, an olefin resin, a silicone resin, a liquid acrylic copolymer, and a phosphate ester compound. Each will be described below.

(Organic lubricant)

In consideration of excessive exudation at room temperature or high temperature, the organic lubricant used in the present invention is preferably a saturated fatty acid bisamide or a fatty acid metal salt. Specifically, ethylene bis stearic acid bisamide, stearic acid metal salt, etc. are mentioned. These may be used alone or in combination of two or more.

In the adhesive resin composition, it is preferable to contain 0.1 to 2 parts by weight of an organic lubricant relative to 100 parts by weight of the block copolymer. The organic lubricant can expect the effect of suppressing the adhesion of the adhesive.

When the content of the organic lubricant is 0.1 parts by weight or more, it is easy to suppress the adhesion of the adhesive force over a high temperature or time, and more preferably 0.2 parts by weight or more.

When the content of the organic lubricant is 2 parts by weight or less, bleed-out is unlikely to occur over a high temperature or time, and there is no fear of contaminating the adherend, but it is more preferably 1 part by weight or less, and particularly preferably 0.5 part by weight or less. .

The organic lubricant used in the present invention is preferably a high melting point in view of high temperature or bleed-out over time, and specifically, ethylenebisstearic acid amide or calcium stearate is mentioned.

(Antioxidant)

The antioxidant used in the present invention is not particularly limited, and examples thereof include phenol-based (monophenol-based, bisphenol-based, polymeric phenol-based), sulfur-based, and phosphorus-based ones.

(Light stabilizer)

Examples of the light stabilizer used in the present invention include hindered amine compounds.

(Ultraviolet absorbent)

It does not specifically limit as an ultraviolet absorber used by this invention, For example, salicylic acid type, benzophenone type, benzotriazole type, cyanoacrylate type etc. are mentioned.

(Softener)

The softener refers to a low-melting-point conjugated polymer having a melting point of 50 ° C or less, a low-melting petroleum-based oil or natural oil, and for example, a low-molecular-weight diene-based polymer, polyisobutylene, hydrogenated polyisobutylene, hydrogen Additive polybutadiene, paraffinic process oil, naphthenic process oil, aromatic process oil, castor oil, tall oil, natural oil, liquid polyisobutylene resin, polybutene, or hydrogenated products thereof can be used. These softeners may be used alone or in combination of two or more.

(Filler)

Examples of the filler include calcium carbonate, magnesium carbonate, silica, zinc oxide, and titanium oxide.

(Protective film)

The protective film of this invention is obtained by laminating the adhesive layer which consists of the said adhesive resin composition on the base material layer. Moreover, you may have a release layer in the base material layer opposite to the adhesion layer.

This will be described in detail below.

(Adhesive layer)

The pressure-sensitive adhesive layer in the present invention is made of the above-mentioned pressure-sensitive adhesive composition, and the thickness is usually about 1 to 30 μm, preferably 2 to 10 μm.

(Base layer)

The base layer in the present invention can be formed of a polyolefin-based resin. Although it does not specifically limit as polyolefin resin contained in a base material, Ethylene homopolymer, ethylene- alpha-olefin copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, and ethylene-vinyl acetate copolymer Polyethylene-based resins such as coalescence; polypropylene-based resins such as propylene homopolymers, propylene-α-olefin copolymers, and propylene-ethylene copolymers; butene homopolymers; homopolymers or copolymers of conjugated dienes such as butadiene and isoprene; Can be heard. Further, examples of the polyethylene-based resin include high density polyethylene, medium density polyethylene, and low density polyethylene. The form of the copolymerization may be random, may be a block, or may be a ternary copolymer. The polyolefin-based resins may be used alone or in combination of two or more.

The polyethylene-based resin is obtained using ethylene as a main component. The proportion of the structural unit derived from ethylene among 100% by weight of the total structural units of the polyethylene-based resin is preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more.

The polypropylene-based resin is obtained by using propylene as a main component. The proportion of structural units derived from propylene among 100% by weight of the total structural units of the polypropylene-based resin is preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more.

The base layer of the present invention is preferably made of a polypropylene-based resin as a main component in view of heat resistance, weather resistance, or adhesion with the adhesive layer.

The thickness of the base layer in the present invention is preferably 10 µm or more, and more preferably 100 µm or less. When the thickness of the substrate is 10 µm or more and 100 µm or less, the handleability of the protective film is further enhanced.

When the protective film of the present invention comprises only the base layer and the adhesive layer made of the adhesive composition, surface irregularities are provided to suppress the surface peeling force between the base layer surface and the adhesive layer surface, and the contact area with the adhesive layer is reduced. It is desirable to do.

In this case, considering the resin composition of the pressure-sensitive adhesive layer of the present invention, it is preferable that the average surface roughness SRa of the surface of the release layer is 0.40 µm or more. The average surface roughness of the surface is more preferably a surface having an SRa of 0.85 µm or less, and particularly preferably 0.50 µm or more and 0.70 µm or less.

When the average surface roughness SRa of the surface of the adhesive layer and the surface opposite to the adhesive layer of the base layer is 0.40 µm or more, the protective performance and peel strength of the adherend can be improved. When the surface roughness of the release layer is lower than 0.40 µm, the drawability of the film is deteriorated when the film is formed into a roll. When the surface roughness of the base layer is higher than 0.85 µm, the surface irregularities of the base layer may be transferred to the surface of the adhesive layer, and the adhesive force may be significantly reduced.

In order to set the average surface roughness SRa to 0.40 µm or more, as a resin to be used for the base layer, an incompatible resin may be added to homo polypropylene or random polypropylene, or a propylene-ethylene block copolymer can be suitably used. When a propylene-ethylene block copolymer is used, the unevenness condition is difficult to change depending on the change of production base or melt kneading conditions at the time of film production, and stable production is possible.

The average surface roughness SRa can be increased by increasing the molecular weight of the ethylene-propylene rubber in the propylene-ethylene block copolymer or increasing the amount of ethylene. In addition, the average surface roughness SRa can be further increased by mixing incompatible resins in the propylene-ethylene block copolymer.

In addition, in the extrusion process described later, the average surface roughness SRa can be further increased by lowering the shearing speed applied to the resin or by increasing the residence time.

On the other hand, in order to reduce the average surface roughness SRa, it is effective to mix a homo polypropylene resin with a propylene-ethylene block copolymer.

As an incompatible resin for the propylene-ethylene block copolymer, an α-olefin (co) polymer having 4 or more carbon atoms such as a 4-methylpentene-1 (co) polymer can be suitably used. Other examples include low-density polyethylene, high-density polyethylene, copolymers of ethylene and a small amount of α-olefins, copolymers of ethylene and vinyl acetate, polystyrene, alicyclic olefin resins, polyester resins, and polyamide resins. Particularly, a 4-methylpentene-1 (co) polymer is preferable because it not only roughens the surface in a matte shape, but also reduces the peeling force by reducing the surface free energy of the film surface.

The amount of the α-olefin (co) polymer having 4 or more carbon atoms in the base layer (resin component constituting the base layer) is in the range of 0% by weight to 35% by weight. When the blending amount of the α-olefin (co) polymer having 4 or more carbon atoms exceeds 35% by weight, when the raw materials of the base layer and the adhesive layer are coextruded using a T die or the like, the film forming properties of the base layer are deteriorated.

(Release layer)

The release layer in the present invention can be provided on the base layer opposite to the adhesive layer. Thereby, by dispersing the function in each of the base layer and the release layer, it is possible to cope with a wider range of uses.

In this case, in order to suppress the peeling force between the surface of the release layer and the surface of the adhesive layer, it is preferable to provide surface irregularities to reduce the contact area with the adhesive layer.

In view of the resin composition of the adhesive layer of the present invention, it is preferable that the average surface roughness SRa of the release layer surface is 0.40 µm or more. The average surface roughness of the surface is more preferably set to a surface having a SRa of 0.850 μm or less, and particularly preferably 0.500 μm or more and 0.700 μm or less.

When the average surface roughness SRa of the surface of the release layer is 0.40 µm or more, the protective performance and peel strength of the adherend can be improved. When the surface roughness of the release layer is lower than 0.40 µm, the drawability of the film is deteriorated when the film is formed into a roll. When the surface roughness of the release layer is higher than 0.850 µm, the surface irregularities of the release layer may be transferred to the surface of the adhesive layer, and the adhesive force may be significantly reduced.

In order to set the average surface roughness SRa to 0.40 µm or more, an incompatible resin may be added to homo propylene or random polypropylene as a resin used for the release layer, or a propylene-ethylene block copolymer can be used very suitably. When a propylene-ethylene block copolymer is used, the unevenness condition is unlikely to change due to the change in production base or melt kneading conditions during film formation, and stable production is possible.

The average surface roughness SRa can be increased by increasing the molecular weight of the ethylene-propylene rubber in the propylene-ethylene block copolymer or increasing the amount of ethylene. In addition, the average surface roughness SRa can be further increased by mixing incompatible resins in the propylene-ethylene block copolymer.

In addition, in the extrusion process described later, the average surface roughness SRa can be further increased by lowering the shearing speed applied to the resin or increasing the residence time.

On the other hand, in order to reduce the average surface roughness SRa, it is effective to mix a homo polypropylene resin with a propylene-ethylene block copolymer.

As an incompatible resin for the propylene-ethylene block copolymer, an α-olefin (co) polymer having 4 or more carbon atoms such as a 4-methylpentene-1 (co) polymer can be suitably used. Other examples include low-density polyethylene, high-density polyethylene, copolymers of ethylene and a small amount of α-olefins, copolymers of ethylene and vinyl acetate, polystyrene, polyester resins, and polyamide resins. In particular, the 4-methylpentene-1 (co) polymer is preferable because it not only roughens the surface in a matte shape, but also reduces the peeling force by reducing the surface free energy of the film surface.

The amount of the α-olefin (co) polymer having 4 or more carbon atoms in the release layer (resin component constituting the release layer) is in the range of 0% by weight to 35% by weight. When the compounding amount of the α-olefin (co) polymer having 4 or more carbon atoms exceeds 35% by weight, when the substrate layer and the adhesive layer are to be laminated by coextrusion, the film forming property of the substrate layer is deteriorated.

The thickness of the release layer is not particularly limited. The thickness of the release layer is preferably 2 µm or more, and preferably 10 µm or less. When the thickness of the release layer is 2 μm or more and 10 μm or less, the handling property of the protective film is further enhanced.

(Characteristics of protective film)

It is preferable that the initial adhesive force of the protective film of this invention is 3 cN / 25 mm or more, and 20 cN / 25 mm or less. If it is 3 cN / 25 mm or more, there is no peeling or lifting during handling or transportation, and if it is less than 20 cN / 25 mm, excessive force is not required when peeling. More preferably, it is 4 cN / 25 mm or more and 15 cN / 25 mm or less. More preferably, it is 5 cN / 25 mm or more and 10 cN / 25 mm or less.

The initial adhesion was measured as follows.

23 ± 2 ° C and relative humidity of 50 ± 5% R, so that the surface of the adhesive layer of the protective film is in contact with the back side of the prism sheet. Under the environment of H., a linear pressure of 15 kN / m was applied from the opposite side of the pressure-sensitive adhesive layer surface of the protective film and adhered at a rate of 2 m / min.

The obtained test piece was 23 ± 2 ° C and a relative humidity of 50 ± 5% R. After being left in the room for 30 minutes in H., 180 degree peel strength (unit: cN) at a width of 25 mm was measured under a condition of peeling speed of 300 mm / min according to JIS Z0237 to obtain an initial adhesive force.

It is preferable that the adhesion elevation rate of the protective film of this invention is 400% or less. When the adhesion enhancement rate is 400% or less, the peeling operation can be performed under more constant conditions, thereby improving the working efficiency. It is more preferably 300% or less, and even more preferably 200% or less.

The adhesion adhesion rate was calculated by the following equation, using initial adhesion and aging adhesion.

It is preferable that the adhesive strength of the protective film of the present invention over time is 3 cN / 25 mm or more and 40 cN / 25 mm or less. When it is 3 cN / 25 mm or more, there is no peeling or lifting during handling or transportation, and when it is 40 cN / 25 mm or less, excessive force is not required when peeling. More preferably, it is 4 cN / 25 mm or more and 40 cN / 25 mm or less. It is more preferably 5 cN / 25 mm or more and 30 cN / 25 mm or less, and particularly preferably 5 cN / 25 mm or more and 20 cN / 25 mm or less.

The adhesive strength with time was measured as follows.

The test piece was produced on the same conditions as the prism sheet used for the measurement of the adhesive strength with time. After standing for 1 week under an atmosphere of 65 ° C ± 2 ° C and a weight of 6 kg / 400 cm2, the 180 degree peel strength at 25 mm width was measured at a peel speed of 300 mm / min according to JIS Z0237, and the adhesive strength over time was measured. Did.

Peelability of the adhesive layer surface of the present invention and the surface of the base layer layer or the release layer surface opposite to the adhesive layer is in the range of 10 cN / 25 mm or less at 23 ° C. In terms of preference. When the peeling force exceeds 10 cN / 25 mm, problems such as partial elongation and deformation of the film occur when the protective film is rolled. The peeling force is more preferably 5 cN / 25 mm or less at 23 ° C, and particularly preferably 3 cN / 25 mm or less.

In addition, the lower limit of the peeling force of the protective film on the surface of the adhesive layer and the surface of the base material layer or the release layer opposite the adhesive layer is a realistic value, and is preferably about 1 cN / 25 mm, more preferably about 2 cN / 25 mm. .

(How to form a protective film)

The method for producing the protective film of the present invention is, for example, a method in which the adhesive composition, the polyolefin resin for the base layer and the polyolefin resin for the release layer are melted and co-extruded from the T-die, if necessary, or laminated to each extruder, or The method of laminating another layer by a lamination method such as extrusion lamination or extrusion coating on a layer obtained by inflation molding, or making each layer independently into a film, and then laminating each obtained film by dry lamination, etc. In view of productivity, co-extrusion molding in which each material of the release layer, the base layer and the pressure-sensitive adhesive layer is supplied and molded in a multi-layer extruder is preferable, and T die molding is more preferable in terms of thickness precision.

The protective film of the present invention is used to protect the surface of an adherend having a smooth or fine irregularities, and is particularly effective when the surface roughness is about 0.1 to 1.0 μm.

Example

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples.

The measurement method is shown below.

(1) Initial adhesion

The obtained surface-laminated film was cut to a size of 150 mm long (winding direction at the time of film production) × 25 mm width (orthogonal to the winding direction at the time of film production) to obtain a test piece, and the pressure-sensitive adhesive layer surface was 150 mm × 35 mm. A test piece was produced by attaching the prism sheet (acrylate-based polymer, SRa = 0.24 µm) to the back side. The patch is 23 ± 2 ℃ and relative humidity is 50 ± 5% R. Under the environment of H., a linear pressure of 20 N / m was applied from the outside of the surface laminated film (ie, opposite to the pressure-sensitive adhesive layer surface) and adhered at a rate of 2 m / min. The following laminator was used for the patch.

Laminator

Manufacturer ： Tester Industry Co., Ltd.

Model ： SA-1010-S

Roll: Heat-resistant silicone rubber roll

Roll diameter: Φ200

The obtained test piece was 23 ± 2 ° C and a relative humidity of 50 ± 5% R. After being left in the room for 30 minutes in H., 180 degree peel strength (unit: cN) at a width of 25 mm was measured under a condition of peeling speed of 300 mm / min according to JIS Z0237 to obtain an initial adhesive force.

(2) adhesive strength with time

The obtained surface protection film was affixed under the same conditions as the prism sheet used for the initial adhesion evaluation of (1), and left for one week in an atmosphere of 65 ° C ± 2 ° C and weighted 6 kg / 400 cm2, then 23 ± 2 ° C and relative Humidity 50 ± 5% R. The inside of H. was allowed to stand for 1 hr, and 180 degree peel strength at a width of 25 mm was measured at a peel speed of 300 mm / min according to JIS Z0237 to obtain adhesive strength over time.

(3) adhesion rate

Using the initial adhesive strength and aging adhesive strength obtained in (1) and (2) above, the rate of change from the initial adhesive strength to aging adhesive strength (adhesive elevation rate) was calculated by the following equation.

(4) Peeling force

The obtained surface protection film was superimposed into two pieces of 110 mm (winding direction at the time of film production) x 40 mm (orthogonal to the winding direction at the time of film production) to obtain a test piece, and the upper and lower portions were sandwiched between copy papers, A weight of 60 kg was placed thereon, and it was left to stand in a room at a temperature of 40 ° C for 72 hr. Thereafter, 23 ± 2 ° C and relative humidity 50 ± 5% R. It was allowed to stand in the interior of H. for 1 hr, and the resistance value when peeled 180 degrees at a rate of 300 mm / min was peeled off using "Autograph (registered trademark)" (AGS-J) manufactured by Shimadzu Corporation. It was set as the force [cN / 25 mm].

At the time of measurement, a polyester sheet having a thickness of 190 µm and a size of 40 mm × 170 mm was prepared as a holding portion of the measurement sample, and was attached to the end of a test piece of 110 mm × 40 mm with cellophane tape at a width of 15 mm to measure it. It was taken as the gripping part. The measurement was performed three times for one sample, and the average value was taken as the peel force of the sample.

5) Elongation and deformation of the film when feeding the film

After obtaining a film roll wound 500 m in a width of 550 mm with a slit, it was stored in a roll state for 7 days in a light-shielding environment at a temperature of 23 ° C and a humidity of 75%. About this storage roll, immediately after winding 300 m onto another plastic core (9 cm in diameter), the film end was gripped by hand and pulled to rewind 3 m. It was visually checked whether the film had partial elongation or deformation when rewinding. Those with no partial elongation or deformation were designated as ○ (good), and those with no partial elongation or deformation were designated as x (poor).

6) Residue or transfer material after peeling from adherend

The obtained surface protection film was affixed under the same conditions as the prism sheet used for the initial adhesion evaluation of (1), and left for one week in an atmosphere of 65 ° C ± 2 ° C and a weight of 6 kg / 400 cm2, followed by 23 ± 2 ° C and relative Humidity 50 ± 5% R. H. was left in the room for 1 hr. Subsequently, the film was peeled off by hand, and the presence or absence of looseness on the back side of the prism sheet was visually confirmed. It was designated as ○ (good) that there was no leftover or transcript, and × (bad) that there was no leftover or transcript.

7) Surface roughness

Evaluation of the surface roughness opposite to the adhesive layer of the obtained protective film was carried out using a three-dimensional roughness meter (manufactured by Kosaka Research Institute, model ET-30HK), with a stylus pressure of 20 mg, a measurement length of 1 mm in the X direction, and a feed speed of 100 µm / sec. , The number of lines recorded at a feed pitch of 2 μm in the Y direction was 99, the height direction magnification was 20000 times, and the cutoff was 80 μm, and was calculated according to the definition of arithmetic mean roughness described in JISB 0601 (1994).

The arithmetic mean roughness (SRa) was evaluated three times each, and evaluated by the average value.

8) Content in block copolymer of aromatic alkenyl compound unit

Each raw resin and mixed resin sample was dissolved in CDCl ₃ to measure 1H-NMR.

9) Content in block copolymer of block A

The content of the block A was calculated by comparing the spectrum of the homo polystyrene with the infrared spectrum of each of the raw resin and mixed resin samples.

10) Weight average molecular weight

Each raw resin and mixed resin sample was dissolved in tetrahydrofuran (sample concentration: 0.05% by weight). Filtration was performed with a 0.20 μm membrane filter, and GPC analysis of the obtained sample solution was performed under the following conditions. The molecular weight was calculated in standard polystyrene conversion.

GPC device conditions

Apparatus: High-speed liquid chromatograph HLC-8220 (TOSOH)

Column: TSKgel SuperHZM-H + SuperHZM-H + SuperHZ2000 (TOSOH)

Solvent: THF (tetrahydrofuran)

Flow rate: 0.35 mL / min

Injection volume: 10 μL

Temperature: 40 ℃

Detector: RI

Data processing: GPC data processing system (TOSOH)

11) Hydrogenation rate of double bond derived from conjugated diene monomer unit in polymer block B

The hydrogenation rate of the double bond derived from the conjugated diene monomer unit in the polymer block B is measured by measuring the content of the carbon-carbon double bond derived from the conjugated diene compound monomer unit in the polymer block B before and after hydrogenation, and the infrared spectrophotometer. , ¹ H-NMR spectrum, etc., and can be determined from the measured values.

The raw material resins used in Examples and Comparative Examples below are shown below.

(1) S1605: Trade name "S1605", hydrogenated product of styrene-butadiene copolymer, manufactured by Asahi Kasei, MFR = 3.5 g / 10 min, hydrogenation rate of double bond derived from conjugated diene unit of polymer block B = 100 mol %, Weight average molecular weight = 180700, density = 1.00 g / cc, content of aromatic alkenyl compound unit = 66% weight%, content of polymer block A = 31 weight%, of structural formula A-B-A and structural formula A-B mixture.

(2) S1606: Trade name "S1606", hydrogenated product of styrene-butadiene copolymer, manufactured by Asahi Kasei, MFR = 4.0 g / 10 min, hydrogenation rate of double bond derived from conjugated diene unit of polymer block B = 100 mol %, Weight average molecular weight = 169900, density = 0.96 g / cc, content of aromatic alkenyl compound units = 50% by weight, content of polymer block A = 25% by weight, structural formulas A-B-A.

(3) H1221: trade name "H1221", hydrogenated product of styrene-butadiene block copolymer, manufactured by Asahi Kasei, MFR = 4.5 g / 10 min, hydrogenation rate of double bond derived from conjugated diene unit = 100 mol%, weight Average molecular weight = 147600, density = 0.89 g / cc, content of aromatic alkenyl compound unit = 12% wt%, content of polymer block A = 12% by weight, no polymer block B.

(4) UH115: trade name "UH115", hydrogenated terpene phenol resin, manufactured by Yasuhara Chemical, glass transition point temperature = 65 ° C

(5) TH130: trade name "TH130", terpene phenol resin, manufactured by Yasuhara Chemical, Euro transition point temperature = 80 ° C

(6) ENDEX155: trade name "Endex (TM) 155 Hydrocarbon Resin, hydrocarbon polymer, manufactured by Eastman Chemical, softening point = 153 ° C

(7) EB-P: Trade name "EB-P", ethylenebisstearic acid amide, manufactured by Gao

(Example 1)

A pressure-sensitive adhesive composition comprising 70 parts by weight of S1606, 5 parts by weight of TH130 and 20 parts by weight of ENDEX155, and a polyolefin resin (trade name "WF836DG3", propylene ethylene random copolymer, manufactured by Prime Polymer Co., Ltd., MFR = 4.5 / 10 min.) Melting point = 164 ° C, ethylene copolymerization amount = 0.3% by weight), and polyolefin resin (trade name "BC3HF", polypropylene-ethylene block copolymer, manufactured by Prime Polymer Co., Ltd., melting point = 171 ° C, ethylene content = 9) as a raw material for the release layer (% By weight), the resin of the adhesive layer is a 40 mmφ single screw extruder with a discharge rate of 4 kg / hour, the resin of the base layer is a 90 mmφ single screw extruder with a discharge amount of 32 kg / hour, and the resin of the release layer is 60 mm. The φ single-screw extruder was co-extruded using a three-layer T die (lip width 850 mm, lip gap 1 mm) at a discharge rate of 4 kg / hour, respectively, cooled with a cooling roll, and the thickness of the adhesive layer, base layer, and release layer. Are 4 μm, 32 μm, and 4 μm, respectively, in the width direction. To obtain a protective film, a length of 650 ㎜. Table 1 shows the results.

(Examples 2 to 4 and Comparative Examples 1 to 9)

A protective film was obtained in the same manner as in Example 1 except that the content of the raw material resin and additives in the adhesive layer and the thickness and content of the adhesive layer were changed as shown in Table 1. Table 1 shows the results.

When the protective films of Examples 1 to 5 were attached to the rear surface of the prism sheet, they had sufficient adhesive strength, and the adhesive strength was hard to be enhanced even after one week under high temperature, and the peeling strength was also suppressed, which was excellent. The peel force of the layer and the opposite side was large, so that the film was difficult to stretch or deform.

On the other hand, the protective film of Comparative Example 1 had an excessively strong adhesion to the prism back surface over time.

The protective film of Comparative Example 2 had a weak initial adhesion to the back side of the prism, and was easy to peel off. In addition, the adhesive strength over time was significantly increased compared to the initial adhesive strength.

The protective film of Comparative Example 3 had an excessively strong adhesion to the back side of the prism and was difficult to peel. Moreover, the peeling force of the adhesive layer of the film and the opposite side was large, and the film was partially stretched or deformed.

The protective film of Comparative Example 4 was too hard to peel because the initial adhesion to the prism back surface and the adhesion over time were too strong. Moreover, the peeling force of the adhesive layer of the film and the opposite side was large, and the film was partially stretched or deformed.

The protective film of Comparative Example 5 was very large in both initial adhesion and aging adhesion to the prism back surface, making it difficult to peel.

The protective film of Comparative Example 6 had a very large adhesive strength with respect to the back side of the prism, and was difficult to peel.

The protective film of Comparative Example 7 had a weak initial adhesion to the back side of the prism and was easy to peel off.

The protective film of Comparative Example 8 had a large initial adhesion to the back side of the prism, and was difficult to peel. Moreover, the peeling force of the adhesive layer of the film and the opposite side was large, and the film was partially stretched or easily deformed.

Industrial availability

The pressure-sensitive adhesive composition of the present invention is useful in industry because the surface protection film of the present invention is suitably used for surface protection, such as a prism sheet, in particular, their back surface.

Claims (11)

An adhesive resin composition comprising a block copolymer satisfying the following 1) and 2) as a main component, and containing α-methylstyrene-based resin and terpene-based resin.
1) It is a block copolymer containing the following polymer block A and the following polymer block B, and having structural formula A-B-A and / or structural formula A-B.
Polymer block A: A polymer block composed mainly of units derived from aromatic alkenyl compound monomer units and mainly derived from aromatic alkenyl compound monomer units.
Polymer block B: Aromatic alkenyl monomer-conjugated diene monomer copolymer block containing randomly derived units derived from conjugated diene monomer units and aromatic alkenyl compound monomer units
2) The hydrogenation rate of the double bond derived from the conjugated diene monomer unit in the polymer block B is 90 mol% or more. According to claim 1,
An adhesive resin composition in which the conjugated diene monomeric unit is a butadiene unit. The method according to claim 1 or 2,
An adhesive resin composition containing 1 to 50 parts by weight of an α-methylstyrene-based resin relative to 100 parts by weight of the block copolymer. The method according to any one of claims 1 to 3,
An adhesive resin composition containing 0.1 to 30 parts by weight of terpene relative to 100 parts by weight of the block copolymer. The method according to any one of claims 1 to 4,
An adhesive resin composition in which the terpene is a terpene phenol resin. The method according to any one of claims 1 to 5,
An adhesive resin composition containing an organic lubricant. The method of claim 6,
An adhesive resin composition containing 0.1 to 2 parts by weight of an organic lubricant relative to 100 parts by weight of the block copolymer. The method of claim 6 or 7,
An adhesive resin composition in which the organic lubricant is ethylenebisstearic acid amide and / or calcium stearate. The protective film which has the adhesive layer which consists of the adhesive resin composition in any one of Claims 1-8, and the base material layer which consists of a polypropylene resin composition. The method of claim 9,
A protective film having a release layer on the opposite side from the adhesive layer. The method of claim 9 or 10,
Protective film used to protect the back of the prism sheet.