JP5452208B2 - Biaxially stretched self-adhesive protective film for in-mold lamination - Google Patents

Description

  The present invention relates to a biaxially stretched self-adhesive protective film for in-mold lamination, more specifically, since it is more flexible than a stretched film of polyethylene terephthalate (hereinafter referred to as PET) or homopolypropylene, Since the elongation is smaller than the unstretched polyethylene film or unstretched polypropylene film and is easy to peel off, it is excellent in workability at the time of processing. Even without adding a tackifier to the surface layer, it has sufficient adhesive strength, and by making the other surface layer a non-adhesive layer, even if the film is rolled up, Blocking is extremely unlikely during use, so it has excellent moldability and can be used for in-mold lamination. Excellent lightness and appearance characteristics, no interface unevenness and no generation of interlayer voids, easy visual inspection of the adherend, no lifting or peeling from the adherend during high temperature processing, and high temperature The present invention relates to a biaxially stretched self-adhesive protective film for in-mold lamination having a low adhesion progress.

Synthetic resin plates such as glass plates and acrylic plates, and materials for liquid crystal display devices such as polarizing plates, retardation films, display mother glasses, and various housings obtained by injection molding (hereinafter referred to as protection objects) However, a protective film is affixed to the surface for the purpose of preventing dust from being attached or scratched during processing, transportation or storage.
This protective film can be easily adhered to the object to be protected, and does not easily peel off during processing, transportation or storage of the object to be protected, but it is easily peeled off when it is necessary to remove it. The property of being able to do so is desired.
In addition, it is necessary for the protective film that is attached to various housings obtained by injection molding through an in-mold lamination process to have a high initial adhesive strength and a low renewal adhesive strength over time at high temperatures. In addition, it is desired that transparency, appearance characteristics, and visual inspection are easy.

At present, the mainstream of the protective film is a non-stretched polyethylene film, a PET film or the like coated with an acrylic or rubber adhesive on one side.
For example, a surface protective film using a uniaxial anisotropic polymer film having a retardation value of 1000 nm or more (see, for example, Patent Document 1) or a surface using a biaxially stretched polymer film is used. Protective film (for example, refer to Patent Document 2), surface protective film using a polymer film having a specific contrast value, retardation value, and haze (for example, refer to Patent Document 3), microwave transmission type molecular orientation meter Surface protective film using a polymer film with a maximum orientation strain of 7 degrees or less measured in (for example, refer to Patent Document 4), a laminated biaxial polyester having excellent transparency and few foreign matters causing coarse protrusions Polarizing plate protective film using a film (for example, refer to Patent Document 5), uniaxial with little foreign matter and scratches, small surface roughness, etc. Surface protective film using the re ester film (for example, see Patent Document 6.) And the like.
Moreover, as a thing using a polyethylene-type film, the surface protection adhesive film (for example, refer patent document 7) which uses the laminated film whose surface 2 layers are polyethylene and a center layer is a polypropylene, For example, the surface protection film using soft polyolefin ( For example, refer to Patent Document 8), a semiconductor wafer surface protecting adhesive film having a high thermal conductivity film layer (for example, refer to Patent Document 9), and biaxially stretched self-adhesive protecting film using PP (for example, Patent References 11 and 12).

However, a protective film using an unstretched polyethylene film has a drawback that the film itself is easily stretched when peeled and is difficult to peel off. In particular, a large screen liquid crystal display device, which is in high demand, has become a more prominent problem because of its large area. Moreover, since it is difficult to produce a wide film, the protective film has a problem that it is not suitable for a liquid crystal display device having a large screen.
Moreover, since the protective film using a PET film is inferior in flexibility, it is difficult to attach, and the PET film itself does not have sufficient adhesive force, so it is necessary to add a tackifier or apply an adhesive. . Such a protection film is inevitably required for such a work, and those with a tackifier added may leave adhesive residue or bleed on the surface of the object to be protected after peeling. There are problems such as dirtying things. In addition, for those that require the application of an adhesive, two steps, a process of producing the original film of the protective film and a process of applying the adhesive to the obtained original film, are required, so productivity is poor, When transferring the resulting raw material to the adhesive coating process, the work environment must be kept clean so that dust and other deposits are not attached to the raw material, resulting in high production costs. ing.

A multilayer film made of a propylene resin composition is disclosed as an olefin resin multilayer wrap film having a self-adhesive surface layer on both sides that does not require the addition of a tackifier or the application of an adhesive. (For example, refer to Patent Document 10). The multilayer film is excellent in productivity and handling because there is no need to add a tackifier or to apply a pressure-sensitive adhesive. However, since both surface layers are self-adhesive layers, the film is rolled during production. When one of the self-adhesive layers sticks to the other self-adhesive layer and blocks, the film cannot be wound evenly and wrinkles are generated. However, it cannot be unwound well. Therefore, it is difficult to give high adhesive strength to the self-adhesive layer, so it can be used sufficiently for applications such as wrap films, but it is used for applications such as protective films that require high adhesion. It was the current situation that I could not get.
In addition, the biaxially stretched self-adhesive protective film described in Patent Document 12 is transparent and can be inspected for protection even in a film-attached state, but when it is attached to an adherend through an in-mold lamination process. In addition, due to the occurrence of unevenness of the interface due to the high crystal component, there is a part that cannot be partially satisfied with the transparency and the inspection property.
Under such circumstances, early development of a polypropylene-based multilayer film that can be used for applications such as a protective film is desired.

JP 2000-94565 A JP 2001-301024 A JP 2001-335648 A JP 2001-335649 A JP 2004-151156 A JP 2005-2220 A JP 7-1681 A JP 2003-103726 A Japanese Patent Laid-Open No. 2004-6552 JP 2006-36225 A JP 2008-221533 A JP 2009-67927 A

  In view of the current state of the art, the object of the present invention is excellent in flexibility, blocking resistance and tackiness, easily peeled off when necessary, suitable for the productivity of wide products, and does not require the addition of tackifiers or adhesive coating Therefore, it is possible to manufacture cleanly and inexpensively, and since there are no interface unevenness and interlayer voids, it has excellent transparency and appearance characteristics when attached to an adherend in an in-mold lamination process. Another object of the present invention is to provide a biaxially stretched self-adhesive protective film that is excellent in heat resistance and therefore does not float or peel off from the adherend during the process and is easy to visually inspect.

  As a result of intensive studies to solve the above problems, the present inventors have determined that a specific polypropylene resin is used for the intermediate layer in the laminated film of at least three layers constituted in the order of self-adhesive layer / intermediate layer / non-adhesive layer. Using the composition, a self-adhesive layer composed of a hydrogenated styrene elastomer and a specific propylene polymer is used on one surface layer, and the main component of a specific propylene / α-olefin random copolymer is used on the other surface layer. And a non-adhesive layer containing a specific amount of an anti-blocking agent for a film, a biaxially stretched laminated film was prepared, and it was found that a self-adhesive protective film having desired characteristics was obtained, and the present invention was completed. It came to.

That is, according to the first invention of the present invention, in the laminated film of at least three layers constituted in the order of self-adhesive layer (X) / intermediate layer (Y) / non-adhesive layer (Z), each layer is A biaxially stretched self-adhesive protective film for in-mold lamination is provided, which satisfies the requirements (1) to (iii).
(A): The intermediate layer (Y) is a propylene-ethylene random copolymer component (a1) 60 to 70 wt% containing propylene units in the range of 98 to 99.9 wt% based on the weight of the copolymer (a1). Propylene resin composition comprising 30 to 40% by weight of a propylene / α-olefin random copolymer component (a2) containing propylene units in the range of 70 to 80% by weight based on the weight of the copolymer (a2) A) 30 to 100% by weight and propylene homopolymer (B) 0 to 70% by weight.
[However, the melt flow rate (MFR _a2 ) of the propylene / α-olefin random copolymer component (a2) is in the range of 4.0 to 15.0 g / 10 min, and the propylene-ethylene random copolymer component (a1) Melt flow rate (MFR _a2 ) of propylene / α-olefin random copolymer component (a2) relative to melt flow rate (MFR _a1 )
The ratio (MFR _a2 / MFR _a1 ) is in the range of 3.0 to 15.0. ]
(B): The self-adhesive layer (X) comprises 55 to 70% by weight of a hydrogenated styrene elastomer (C) and 30 to 45% by weight of a propylene homopolymer (D).
(C): Non-adhesive layer (Z) is blended with 0.5 to 1.5 parts by weight of anti-blocking agent for film (F) with respect to 100 parts by weight of propylene / α-olefin random copolymer (E). It consists of a polymer composition.
[However, the propylene / α-olefin random copolymer (E) is a propylene-ethylene random copolymer or propylene-ethylene-1 butene random copolymer having a melting point of 125 to 145 ° C. The anti-blocking agent (F) has an average particle diameter measured by a laser diffraction method of 1.0 to 5.0 μm. ]

  Moreover, according to the second invention of the present invention, in the first invention, the adhesive strength conforming to the adhesive strength measuring method (held at 23 ° C. and 50 RH% for 24 hours) defined in JIS Z0237 (2000). Biaxially stretched self-molding for in-mold lamination, characterized in that the adhesive strength (initial adhesive strength) is 30 g / 25 mm or more when held for 30 minutes in an atmosphere of 23 ° C. and 50% RH. An adhesive protective film is provided.

According to a third aspect of the present invention, in the in-mold lamination according to the first or second aspect, the haze of the film measured in accordance with JIS K7105 (1981) is 8% or less. A biaxially stretched self-adhesive protective film is provided.
Furthermore, according to the fourth invention of the present invention, in any one of the first to third inventions, the self-adhesive layer (X) does not contain a tackifier, and is biaxially stretched for in-mold lamination. A self-adhesive protective film is provided.

As described above, the present invention relates to a biaxially stretched self-adhesive protective film for in-mold lamination, and preferred embodiments thereof include the following.
(1) The α-olefin of the propylene / α-olefin random copolymer component (a2) used for the intermediate layer (Y) is ethylene or an α-olefin having 4 to 18 carbon atoms, preferably ethylene or 1-butene. A biaxially stretched self-adhesive protective film for in-mold lamination as described above.
(2) The in-mold lamination described above, wherein the propylene homopolymer (B) used for the intermediate layer (Y) has a melt flow rate (MFR) in the range of 2.5 to 8.0 g / 10 min. Biaxially stretched self-adhesive protective film.
(3) The hydrogenated styrene elastomer (C) used in the self-adhesive layer (X) is a hydrogenated styrene-butadiene copolymer (HSBR) having a styrene content of 30% by weight or less. Biaxially stretched self-adhesive protective film for in-mold lamination.
(4) Biaxial stretching for in-mold lamination, wherein the antiblocking agent for film (F) used for the non-adhesive layer (Z) is silica fine particles, synthetic silica fine particles or polymethyl methacrylate fine particles Self-adhesive protective film.
(5) The biaxially stretched self-adhesive protective film for in-mold lamination described above, wherein the stretching ratio is 3 to 7 times in the machine direction (MD) and 4 to 10 times in the transverse direction (TD).
(6) The biaxially stretched self-adhesive protective film for in-mold lamination described above, wherein the total thickness of the film is 20 to 80 μm.
(7) Elastic modulus measured according to JIS K7127 (1999) is 400 to 1400 MPa in the machine direction (MD) and 700 to 3600 MPa in the transverse direction (TD). Biaxially stretched self-adhesive protective film.
(8) The in-break elongation measured in accordance with JIS K7127 (1999) is 100 to 300% in the machine direction (MD) and 30 to 300% in the transverse direction (TD). Biaxially stretched self-adhesive protective film for mold lamination.

  The biaxially stretched self-adhesive protective film for in-mold lamination of the present invention is kept at a high temperature for a long period of time because it is difficult to increase the adhesive force even if the film is held in a state of being adhered to a protection object. Even if it is a film which is easy to peel off, when this film is peeled off, the surface of the object to be protected is peeled off and the object to be protected is not damaged. Furthermore, it retains heat resistance against the heat applied during pre-forming in the in-mold lamination mold forming process, does not cause floating or peeling, has excellent transparency and appearance characteristics, and can be easily visually observed. Inspection is possible.

As described above, the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention comprises at least three layers configured in the order of self-adhesive layer (X) / intermediate layer (Y) / non-adhesive layer (Z). In the laminated film, each layer satisfies the following requirements (A) to (C).
(A): The intermediate layer (Y) comprises 60 to 70% by weight of a propylene-ethylene random copolymer component (a1) containing propylene units in a range of 98 to 99.9% by weight based on the weight of the copolymer; Propylene-based resin composition (A) 30 to 30 consisting of 30 to 40% by weight of a propylene / α-olefin random copolymer component (a2) containing propylene units in the range of 70 to 80% by weight based on the weight of the copolymer It consists of 100% by weight and 0 to 70% by weight of the propylene homopolymer (B).
[However, the melt flow rate (MFR _a2 ) of the propylene / α-olefin random copolymer component (a2) is in the range of 4.0 to 15.0 g / 10 min, and the propylene-ethylene random copolymer component (a1) in the melt flow rate range of the ratio _(MFR a2 / MFR _a1) is 3.0 to 15.0 in melt flow rate of the propylene · alpha-olefin random copolymer component to the _{(MFR a1) (a2) (} MFR a2) is there. ]
(B): The self-adhesive layer (X) is composed of 55 to 70% by weight of a hydrogenated styrene elastomer (C) and 30 to 45% by weight of a propylene polymer (D).
(C): Non-adhesive layer (Z) is blended with 0.5 to 1.5 parts by weight of anti-blocking agent for film (F) with respect to 100 parts by weight of propylene / α-olefin random copolymer (E). It consists of a polymer composition.
[However, the propylene / α-olefin random copolymer (E) is a propylene-ethylene random copolymer or propylene-ethylene-1 butene random copolymer having a melting point of 125 to 145 ° C. The anti-blocking agent (F) has an average particle diameter measured by a laser diffraction method of 1.0 to 5.0 μm. ]
Hereinafter, the components of each layer, the characteristics of the laminated film, the production method, etc. will be described in detail.

I. Components of each layer Constituent Components of Intermediate Layer (Y) The intermediate layer (Y) constituting the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention is composed of 30 to 100% by weight of propylene-based resin composition (A) and propylene alone It consists of 0 to 70% by weight of the blend (B), preferably 40 to 80% by weight of the propylene resin composition (A) and 20 to 60% by weight of the propylene homopolymer (B). When the content of the propylene-based resin composition (A) is extremely less than 30% by weight, the flexibility of the film tends to be lowered and it tends to be difficult to stick it well. However, in order to improve the flexibility of the film, if a propylene resin composition other than the propylene resin composition (A) is used, the adhesion between the intermediate layer and the adhesive layer / non-adhesive layer and stretching during film formation Due to the poor properties, problems such as interface unevenness and interlayer voids occur, and the heat resistance of the film is not sufficient, so that problems such as floating and peeling occur in the in-mold lamination process.

(1) Propylene resin composition (A)
The propylene-based resin composition (A) used for the intermediate layer (Y) of the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention comprises a propylene-ethylene random copolymer component (a1) (hereinafter referred to as ( a1) component may be represented by 60 to 70% by weight, and propylene / α-olefin random copolymer component (a2) (hereinafter may be represented by component (a2)) by 30 to 40. It is contained in the range of wt%, and preferably contains the component (a1) in the range of 62 to 68 wt% and the component (a2) in the range of 33 to 38 wt%.
When the content of the component (a1) is extremely less than 60% by weight, the elasticity of the resulting biaxially stretched self-adhesive protective film is lowered, so that the flexibility of the film becomes excessive and the blocking of the product is deteriorated. Tend to. On the other hand, when the content of the component (a1) is extremely higher than 70% by weight, the elasticity of the resulting biaxially stretched self-adhesive protective film for in-mold lamination increases, so that the flexibility is poor and the adhesive strength Tends to decrease.

The propylene-based resin composition (A) may be obtained by simply mixing the (a1) component and the (a2) component, or may be obtained by continuous polymerization by multistage polymerization.
As a simple mixing method, a propylene / α-olefin random copolymer polymerized using a Ziegler-Natta catalyst, or a method of melt-mixing a commercially available ethylene-propylene rubber and a propylene polymer can be presented. The method of melt mixing is not particularly limited, and a known method can be employed.
In addition, as a method for continuously polymerizing the component (a1) and the component (a2) by multistage polymerization, a plurality of polymerization vessels are used, for example, the component (a1) is produced in the first stage, and the second stage. In (a2), the method of manufacturing a component can be illustrated. This continuous polymerization method is preferable in that the propylene-based resin composition (A) in which the component (a2) is uniformly dispersed in the component (a1) can be obtained and the quality can be stabilized as compared with the melt mixing method described above. . The method for continuously polymerizing by the multistage polymerization method is not particularly limited, and a known method can be adopted.

  The component (a1) is a propylene-ethylene random copolymer containing propylene units in the range of 98 to 99.9% by weight, preferably 98.5 to 99.9% by weight, based on the weight of the copolymer (a1). is there. When the propylene unit is significantly less than 98% by weight, the flexibility of the biaxially stretched self-adhesive protective film becomes excessive, and the blocking tends to deteriorate. On the other hand, when the propylene unit is 100% by weight, the compositional difference from the component (a2) becomes large and the transparency tends to be inferior.

The component (a2) is a propylene / α-olefin random copolymer containing propylene units in the range of 70 to 80% by weight, preferably 72 to 78% by weight, based on the weight of the copolymer (a2). When the propylene unit is significantly less than 70% by weight, the transparency of the resulting biaxially stretched self-adhesive protective film for in-mold lamination tends to be reduced, whereas when the propylene unit is significantly greater than 80% by weight, it is obtained. The elastic modulus of the biaxially stretched self-adhesive protective film for in-mold lamination tends to increase and the adhesive strength tends to decrease.
Examples of the α-olefin include ethylene or an α-olefin having 4 to 18 carbon atoms. Specific examples of the α-olefin having 4 to 18 carbon atoms include 1-butene, 1-pentene, 1-hexene, Examples include 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 3-methyl-1-pentene. One or more of these can be used. From the viewpoint of production cost, ethylene, 1-butene or a combination thereof is most preferable.

In the propylene resin composition (A), the melt flow rate (MFR _a2 ) (test condition: 230 ° C., 2.16 kg load) of the component (a2) is the biaxially stretched self-adhesive property for in-mold lamination obtained. From the viewpoint of the transparency and formability of the protective film, it is in the range of 4.0 to 15.0 g / 10 min, and preferably 7.5 to 12.5 g / 10 min. When MFR _a2 is significantly lower than 4.0 g / 10 min, the dispersibility of the component (a2) with respect to the component (a1) tends to be poor, and transparency may be hindered. On the other hand, when MFR _a2 greatly exceeds 15.0 g / 10 min, the melt flow rate (MFR _Hole ) of the entire propylene-based resin composition (A) becomes too high, which causes adverse effects as described later.
(A2) component of the melt flow rate _{(MFR a2)} is the time of polymerization can be adjusted by the supply of hydrogen.

Further, the propylene-based resin composition in (A), (a2) ratio component has a melt flow rate _{(MFR a2)} of component (a1) has a melt flow rate _{(MFR a1) (MFR a2 /} MFR a1) is obtained From the viewpoint of transparency and moldability of the biaxially stretched self-adhesive protective film for in-mold lamination, it is in the range of 3.0 to 15.0, and preferably 5.5 to 9.5. Here, MFR _a2 / MFR _a1 is a scale representing the dispersion state of the component (a1) and the component (a2). If MFR _a2 / MFR _a1 is significantly lower than 3.0, the dispersibility of the component (a2) with respect to the component (a1) tends to be poor, and transparency may be hindered. On the other hand, when MFR _a2 / MFR _a1 greatly exceeds 15.0, not only the dispersibility of the components (a1) and (a2) tends to be poor, but also the melt flow rate (MFR) of the propylene-based resin composition (A). _(Whole ) becomes too high, which causes adverse effects as described below.
The ratio (MFR _a2 / MFR _a1 ) can be adjusted by the respective hydrogen supply amounts during the first and second stage polymerizations.

The melt flow rate (MFR _Whole ) of the entire propylene resin composition (A) is 1.0 to 5.0 g from the viewpoint of the transparency and moldability of the obtained biaxially stretched self-adhesive protective film for in-mold lamination. / 10 min is preferable, and 1.5 to 4.5 g / 10 min is more preferable.
When the melt flow rate (MFR _Whole ) of the propylene-based resin composition (A) is significantly lower than 1.0 g / 10 min, a large load is applied to the extruder when the resin is extruded, which is not preferable. On the other hand, if it exceeds 5.0 g / 10 min, the melt tension of the extruded resin is weak, or the tension at the time of stretching becomes weak, and there is a possibility that it cannot be satisfactorily stretched.
Here, the melt flow rate (MFR) is JIS K7210 (1999), “Method A, Condition M (230 ° C.) of“ Plastics—Test Methods for Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) of Thermoplastic Plastics ”. , 2.16 kg load).

(2) Propylene homopolymer (B)
The propylene homopolymer (B) used in the present invention preferably has a melt flow rate (MFR) in the range of 2.5 to 8.0 g / 10 min, more preferably a melt flow rate of 3.0 to 7. A propylene homopolymer in the range of 0.0 g / 10 min can be exemplified, and a mixture of two or more may be used.
Here, the melt flow rate (MFR) is JIS K7210 (1999), “Method A, Condition M (230 ° C.) of“ Plastics—Test Methods for Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) of Thermoplastic Plastics ”. , 2.16 kg load).

  The propylene homopolymer (B) can be obtained by using a highly stereoregular polymerization catalyst. As the highly stereoregular polymerization catalyst, a titanium compound prepared using titanium chloride, alkoxy titanium or the like as a starting material is used. So-called Ziegler-Natta catalysts or Kaminsky catalysts using metallocene compounds can be used.

2. Components of the self-adhesive layer (X) The self-adhesive layer (X) constituting the biaxially stretched self-adhesive protect film for in-mold lamination of the present invention comprises 55 to 70% by weight of a hydrogenated styrene elastomer (C), Propylene homopolymer (D) 30 to 45% by weight, preferably hydrogenated styrene elastomer (C) 60 to 70% by weight, propylene homopolymer (D) 30 to 40% by weight . The adhesive strength of the self-adhesive layer (X) can be controlled by adjusting the hydrogenated styrene-based elastomer (C) and the propylene homopolymer (D) within the above range.
When the added amount of the hydrogenated styrene elastomer (C) is extremely less than 55% by weight, the flexibility of the self-adhesive layer is lowered and the adhesiveness tends to be inferior. On the other hand, when the amount of hydrogenated styrene elastomer (C) added is extremely greater than 70% by weight, the flexibility of the self-adhesive layer increases, the molding processability decreases, the product blocking and peelability deteriorate. Moreover, there is a tendency that the renewal adhesive strength with time increases too much.

(1) Hydrogenated styrene elastomer (C)
Examples of the hydrogenated styrene elastomer (C) used in the present invention include a hydrogenated styrene-butadiene copolymer (HSBR), a styrene-ethylene-butylene-ethylene copolymer (SEBC), and a styrene-ethylene-butylene-styrene copolymer. A polymer (SEBS) etc. can be illustrated, and hydrogenated styrene-butadiene copolymer (HSBR) is particularly preferable. In order for the biaxially stretched self-adhesive protective film to have sufficient adhesive strength, the styrene content of the hydrogenated styrene-based elastomer (C) is preferably 30% by weight or less, and preferably 20% by weight or less. Further preferred. On the other hand, when the styrene content exceeds 30% by weight, the flexibility of the adhesive layer is inferior and the adhesive strength tends to decrease.
As such a hydrogenated styrene-based elastomer (C), commercially available products can be used, and specific examples include Dynalon 1320P manufactured by JSR Corporation.

(2) Propylene homopolymer (D)
The propylene homopolymer (D) used for the self-adhesive layer (X) according to the present invention is not particularly limited as long as it has a melt flow rate of a polypropylene resin generally used for a film. The range of the melt flow rate (MFR) described in the propylene homopolymer (B) is preferable.
The propylene homopolymer (D) can be obtained by using a highly stereoregular polymerization catalyst. As the highly stereoregular polymerization catalyst, a titanium compound prepared using titanium chloride, alkoxy titanium or the like as a starting material is used. So-called Ziegler-Natta catalysts or Kaminsky catalysts using metallocene compounds can be used.

3. Constituent component of non-adhesive layer (Z) The non-adhesive layer (Z) constituting the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention is 100% by weight of propylene / α-olefin random copolymer (E). In contrast, 0.5 to 1.5 parts by weight of anti-blocking agent for film (F) is blended, and preferably 100 parts by weight of propylene / α-olefin random copolymer (E) for film. Antiblocking agent (F) is blended in an amount of 0.8 to 1.2 parts by weight.
More preferably, as the propylene / α-olefin random copolymer (E), 100 parts by weight of the propylene / ethylene / 1-butene random copolymer (E) is used as an antiblocking agent for film (F) 0.8 to It is 1.2 parts by weight, and controls the transparency of the film and the surface roughness of the non-adhesive layer (Z) by adjusting the blending amount of the antiblocking agent for film (F) within the above range. Can do.
When 100 parts by weight of the propylene / α-olefin random copolymer (E) is extremely less than 0.5 parts by weight of the antiblocking agent for film (F), the self-adhesive layer (X) and non-adhesive Layer (Z) blocking tends to worsen. On the other hand, when the addition amount of the antiblocking agent for film (F) is extremely larger than 1.5 parts by weight, the transparency of the film tends to deteriorate.

(1) Propylene / α-olefin random copolymer (E)
The propylene / α-olefin random copolymer (E) used in the present invention has a melting point in the range of 125 ° C to 145 ° C. When the melting point exceeds 145 ° C., there is a risk of appearance failure during film stretching. On the other hand, the propylene / α-olefin random copolymer (E) having a melting point of less than 125 ° C. is difficult to produce, It is preferable that it is 125 to 145 degreeC.
Here, the melting point is a value measured by a differential scanning calorimetry method (DSC method) based on a method defined in JIS K7122 (1987).

The propylene / α-olefin random copolymer (E) used in the present invention preferably contains propylene units in the range of 85 to 99.9% by weight, more preferably 90 to 99.9% by weight. It is desirable to include in the range. Propylene / α-olefin random copolymer (E) having a propylene unit of less than 85% by weight is difficult to produce and cannot be practically used.
The propylene / α-olefin random copolymer (E) used in the present invention is a biaxially stretched self-adhesive protective film for in-mold lamination according to the present invention. It is desirable not to use other polymers because it is effective in preventing the occurrence of floating and peeling from the adherend, but the amount is preferably small so that the effect of the present invention is not significantly impaired, preferably within 10% by weight. For example, it may be used.

(2) Anti-blocking agent for film (F)
The antiblocking agent for film (F) used in the present invention has an average particle size of 1.0 to 5.0 μm, preferably 2.0 to 4.0 μm. If the average particle size is significantly less than 1.0 μm, the anti-blocking effect tends to decrease. On the other hand, if the average particle size is more than 5.0 μm, not only the testability of the film deteriorates but also the film and protection The surface of the object may be damaged, or the anti-blocking agent may fall off from the film, causing troubles, which is not preferable.
Here, the average particle diameter is a value measured by a laser diffraction method.
As such an anti-blocking agent for film (F), general anti-blocking agents such as silica fine particles, synthetic silica fine particles, and polymethyl methacrylate fine particles can be used. Specific examples of commercially available products include Silicia 550 manufactured by Fuji Silysia Co., Ltd.

  Such a method for mixing the antiblocking agent for film (F) and the propylene / α-olefin random copolymer (E) is a known method such as using a mixer with a high-speed stirrer such as a Henschel mixer (trade name). Can be mixed uniformly by mixing and mixing. Furthermore, after mixing the antiblocking agent for film (F) and the propylene / α-olefin random copolymer (E), it is mixed more uniformly by pelletizing using a single screw extruder or a twin screw extruder. This is preferable.

4). Other components Antioxidants used in ordinary polyolefin film materials are used for the self-adhesive layer (X) / intermediate layer (Y) / non-adhesive layer (Z) constituting the laminated film used in the present invention. Additives such as an agent and a neutralizing agent may be blended.

  Antioxidants include tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, 2,6-di-t-butyl-4-methylphenol, Phenolic compounds such as n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate and tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate Antioxidant, or tris (2,4-di-t-butylphenyl) phosphite, tris (nonylphenyl) phosphite, distearyl pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) Examples thereof include phosphorus-based antioxidants such as -4,4'-biphenylene-diphosphonite.

  Examples of the neutralizing agent include metal salts of higher fatty acids such as calcium stearate and hydrotalcites.

  The amount of these additives is preferably about 0.01 to 3% by weight in each layer. Moreover, the method of mix | blending these additives is not specifically limited, For example, it can mix | blend by a well-known method, such as using a mixer with a high-speed stirrer, such as a Henschel mixer (brand name). Furthermore, after mixing the various compounds constituting each layer, it may be pelletized using a single screw extruder or a twin screw extruder.

II. Biaxially stretched self-adhesive protect film for in-mold lamination The biaxially stretched self-adhesive protect film for in-mold lamination of the present invention comprises a layer having the above-described constituents as a self-adhesive layer (X) / intermediate layer (Y) / It is a laminated film of at least 3 layers comprised in order of a non-adhesion layer (Z).
In addition, another layer is included between the self-adhesive layer (X) and the intermediate layer (Y) and between the intermediate layer (Y) and the non-adhesive layer (Z) as long as the effects of the present invention are not impaired as necessary. It does not matter.

The manufacturing method of the laminated film is formed into a sheet by a normal T-die method or an inflation method so as to be configured in the order of self-adhesive layer (X) / intermediate layer (Y) / non-adhesive layer (Z). It is obtained by biaxially stretching a sheet formed by the method. As the biaxial stretching method, a sequential biaxial stretching method by a tenter method is preferable.
The stretching ratio of the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention is preferably 3 to 7 times and 4 to 10 times in the machine direction (MD) and the transverse direction (TD), respectively, more preferably, It is desirable that they are 4 to 6 times and 4 to 9 times, respectively. If the draw ratio is out of the above range, the elastic modulus and elongation of the film may not be suitable for use as a protective film.

  The thickness of the self-adhesive layer (X) in the biaxially stretched self-adhesive protect film for in-mold lamination of the present invention is in the range of 1 to 6 μm, from 1.5 to 5 μm from the viewpoint of adhesiveness and molding processability. Those are preferred. When the thickness of the self-adhesive layer (X) of the protective film is extremely thinner than 1 μm, the adhesive force tends to be lowered and it becomes difficult to stick. On the other hand, when the self-adhesive layer (X) thickness of the protective film is extremely thicker than 6 μm, when extruding the self-adhesive layer (X) during film production, the load on the extruder becomes too high or it cannot be uniformly extruded. Therefore, it is difficult to produce a good film.

  The total thickness of the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention is preferably 20 to 80 μm, more preferably 25 to 50 μm, from the viewpoints of adhesiveness, flexibility, transparency, and moldability. When the thickness of the protective film is extremely thinner than 20 μm, the elastic modulus is lowered and it tends to be difficult to peel off. On the other hand, when the thickness of the protective film is extremely thicker than 80 μm, the elastic modulus increases, it becomes difficult to adhere well to the object to be protected, and the tackiness tends to decrease.

  The elastic modulus of the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention is preferably 400 to 1400 MPa and 700 to 3600 MPa in the machine direction (MD) and the transverse direction (TD), respectively, more preferably 600 to 600, respectively. It is desirable that the pressure be 1200 MPa, 1200 to 2800 MPa. When the elastic modulus of the film is much lower than the respective lower limit values, flexibility tends to increase and blocking tends to occur. On the other hand, when the elastic modulus of the film greatly exceeds the respective upper limit values, it tends to be difficult to adhere to the object to be protected and the adhesiveness tends to decrease.

  The breaking elongation of the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention is preferably 100 to 300% and 30 to 300% in the machine direction (MD) and the transverse direction (TD), respectively, more preferably, It is desirable to be 120-200% and 40-200%, respectively. When the elongation of the film greatly exceeds the respective upper limit values, the elongation tends to be large and difficult to peel off.

The biaxially stretched self-adhesive protective film for in-mold lamination of the present invention is easy to stick and peel by softening the adhesive layer as described above or controlling the elastic modulus and elongation at break of the film. Easy protective film. The initial adhesive strength between the film and the acrylic plate is preferably 3 g / 25 mm or more. When the initial adhesive strength is significantly less than 3 g / 25 mm, there is a tendency that the protective object does not adhere well.
Here, the initial adhesive strength with the acrylic plate is a mirror-like acrylic plate (“Acrylite L001” 3 mm plate manufactured by Mitsubishi Rayon Co., Ltd.) instead of SUS304 in accordance with the method specified in JIS Z0237 (2000). ) And measure as follows.
A self-adhesive layer of a biaxially stretched self-adhesive protect film cut to a width of 25 mm and a length of 200 mm is aligned with an acrylic plate, and is uniformly adhered at a constant pressure using a rubber roller with a load of 2 kg, at 23 ° C. and 50 RH%. After holding for 30 minutes under an atmosphere, the acrylic plate is fixed, and the strength when one end of the film is peeled 180 degrees at a constant rate of 300 mm / min is measured.

The biaxially stretched self-adhesive protective film for in-mold lamination of the present invention can control the flexibility of the adhesive layer as described above, thereby suppressing the increase in the renewed adhesive strength over time while having the initial adhesive strength. it can. The renewal adhesive strength with time between the film and the acrylic plate is preferably 100 g / 25 mm or less. When the renewal adhesive strength with time greatly exceeds 100 g / 25 mm, not only is it difficult to peel off from the object to be protected, but also when the film is peeled off, the surface of the object to be protected may be peeled off and the object to be protected may be damaged.
Here, the time-renewed adhesive strength with the acrylic plate is a mirror-like acrylic plate (“Acrylite L001” manufactured by Mitsubishi Rayon Co., Ltd., 3 mm) instead of SUS304 in accordance with the method specified in JIS Z0237 (2000). Plate) and measure as follows.
After aligning the self-adhesive layer of the biaxially stretched self-adhesive protective film for in-mold lamination, cut to a width of 25 mm and a length of 200 mm, with an acrylic plate, and using a rubber roller with a load of 2 kg, it is uniformly adhered at a constant pressure, After holding for 3 hours in an atmosphere of 110 ° C. and relative humidity, the acrylic plate is fixed, and the strength when one end of the film is peeled 180 ° at a constant speed of 300 mm / min is measured.

  In addition, the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention basically does not require kneading of a tackifier or application of an adhesive as used in conventional protective films, It has sufficient adhesive strength. Therefore, secondary processing is not required and equipment and man-hours can be omitted. In addition, there is also an advantage that after peeling off from the protection target, problems such as adhesive residue and bleed adherence do not occur on the surface of the protection target.

The biaxially stretched self-adhesive protective film for in-mold lamination of the present invention suppresses blocking that occurs when the self-adhesive layer and the non-adhesive layer are superposed on each other. In order to improve the quality, the non-adhesive layer having a roughened surface is provided. Blocking strength between self-adhesive layer and the non-adhesive layer is preferably is adjusted to 3000 g / 4 cm ² or less, more preferably 2000 g / 4 cm ² or less. When the blocking strength of the self-adhesive layer and the non-adhesive layer is high, there is a tendency that wrinkles occur on the mill roll when the product film is wound, or the films stick to each other during use and cannot be unwound well.

The biaxially stretched self-adhesive protective film for in-mold lamination of the present invention can prevent blocking by controlling the surface roughness state of the non-adhesive layer, but on the other hand, the transparency of the film deteriorates. There is a tendency. When the haze greatly exceeds 8%, the transparency is lowered, and it tends to be difficult to check the state of the object to be protected at the time of product inspection or the like.
Therefore, the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention preferably has a haze of 8% or less.
Here, the haze is a value measured according to a method specified in JIS K7105 (1981) “Testing method for optical properties of plastic”.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited by these.
In addition, the physical-property value of the film used by the Example of this invention and a comparative example was measured by the method shown below, and the sample used was as follows.

1. Test method (1) MFR [unit: g / 10 min]:
MFR conforms to JIS K7210 (1999) “Method of testing plastic-thermoplastic melt mass flow rate (MFR) and melt volume flow rate (MVR)”, condition M (230 ° C., 2.16 kg load). And measured.

(2) Initial adhesive strength [g / 25 mm]:
In accordance with the method specified in JIS Z0237 (2000) “Adhesive tape / adhesive sheet test method”, instead of SUS304, a mirror-like acrylic plate (“Acrylite L001” 3 mm plate manufactured by Mitsubishi Rayon Co., Ltd.) is used. Measurement was performed as follows.
The self-adhesive layer of a biaxially stretched self-adhesive protective film cut to a width of 25 mm and a length of 200 mm is aligned with an acrylic plate and uniformly adhered with a constant pressure using a rubber roller with a load of 2 kg, and then 23 ° C., 50 RH After being held for 30 minutes in a% atmosphere, the acrylic plate was fixed, and the strength was measured when one end of the film was peeled 180 degrees at a constant rate of 300 mm / min. The higher the value, the greater the initial bond strength.

(3) Update adhesive strength with time [g / 25mm]:
In accordance with the method specified in JIS Z0237 (2000) “Adhesive tape / adhesive sheet test method”, instead of SUS304, a mirror-like acrylic plate (“Acrylite L001” 3 mm plate manufactured by Mitsubishi Rayon Co., Ltd.) is used. Measurement was performed as follows.
The self-adhesive layer of the biaxially stretched self-adhesive protective film cut to a width of 25 mm and a length of 200 mm is aligned with the acrylic plate, and is uniformly adhered at a constant pressure using a rubber roller with a load of 2 kg. After holding for 3 hours in a humidity atmosphere, the acrylic plate was fixed, and the strength when one end of the film was peeled 180 degrees at a constant rate of 300 mm / min was measured. The larger the value, the greater the adhesive strength with time.

(4) Heat resistance:
In accordance with the method specified in JIS Z0237 (2000) “Adhesive tape / adhesive sheet test method”, a mirror-like PC board (“Epocarbonate EC1” manufactured by Nippon Polyester Co., Ltd.) is used instead of SUS304. Was measured as follows.
The self-adhesive layer surface of the film cut to a width of 40 mm and a length of 50 mm is aligned with the PC plate, and is adhered uniformly at a constant pressure using a rubber roller with a load of 2 kg, and then kept at 150 ° C. and relative humidity for 30 minutes. After the film was lifted and peeled off, it was confirmed. The evaluation criteria are as follows.
◎ ・ ・ ・ There is no floating / peeling on the film, and it is neatly attached to the PC board.
○: The film is not lifted or peeled off, but is stuck to the PC plate in a state where the film edge is pulled by the shrinkage of the film.
X: Either floating or peeling occurs on the film.

(5) Haze [Unit:%]:
Measured according to the method specified in JIS K7105 (1981) “Testing method for optical properties of plastic”. The smaller the value, the lower the haze and the higher the transparency.

(6) Peelability:
(I) Roll feeding evaluation:
The film was wound up 1000 m, left in an atmosphere of 35 ° C. and 60% RH for 24 hours, and then judged by peeling marks and peeling sound when it was fed out at a speed of 500 m / min. The evaluation criteria are as follows.
◎ ・ ・ ・ No peeling mark or peeling sound.
○: There is no peeling mark but there is peeling sound.
Δ: There is no peeling mark, but there is a peeling sound, and a considerable tension is required for feeding.
X: There is a peeling mark.

(Ii) Product peeling:
In accordance with the method specified in JIS Z0237 (2000) “Adhesive tape / adhesive sheet test method”, a mirror-like PC board (“Epocarbonate EC1” manufactured by Nippon Polyester Co., Ltd.) is used instead of SUS304. Was measured as follows.
The self-adhesive layer surface of the film cut to a width of 25 mm and a length of 200 mm is aligned with the PC board, and it is kept in close contact at a constant pressure using a rubber roller with a load of 2 kg, and then kept at 110 ° C. and relative humidity for 3 hours. Thereafter, the film was held at one end and evaluated by peelability and tearability when peeled with one hand. The evaluation criteria are as follows.
A: Easily peels off.
○ ・ ・ ・ There is peeling resistance but peels easily.
X: Peeling resistance is strong and tearing is difficult to peel off.

(7) Inspection property:
In accordance with the method specified in JIS Z0237 (2000) “Adhesive tape / adhesive sheet test method”, a mirror-like PC board (“Epocarbonate EC1” manufactured by Nippon Polyester Co., Ltd.) is used instead of SUS304. Was measured as follows.
The self-adhesive layer surface of the film cut to a width of 40 mm and a length of 50 mm is aligned with a PC plate, and is adhered uniformly with a constant pressure using a rubber roller with a load of 2 kg. The detectability of the defects of the plate was evaluated. The evaluation criteria are as follows.
A: The defects of the PC board can be easily determined.
○: Defects of the PC board can be judged.
X: The defect of the PC plate cannot be judged, or the defect of the PC plate and the defect of the film cannot be distinguished.

2. Resin used Various materials used in Examples and Comparative Examples are shown below.
(1) PP-1 (propylene resin composition (A)):
(A1) Multi-stage polymer of 65% by weight of component and 35% by weight of (a2) component: MFR _Whole ; 2.8 g / 10 min (The details of the production will be described later as a polymerization example.)
(A1) Propylene-ethylene random copolymer component: propylene content; 99.2% by weight, MFR _a1 ; 1.4 g / 10 min
(A2) Propylene-ethylene-1 butene random copolymer component: propylene content; 75 wt%, MFR _a2 ; 10 g / 10 min

(2) PP-2 (propylene homopolymer (B) or (D)):
FL0007 (trade name) manufactured by Nippon Polypro Co., Ltd., which is a propylene homopolymer having a melting point of 161 ° C.

(3) PP-3 (propylene polymer):
FB3EBT (trade name) manufactured by Nippon Polypro Co., Ltd., which is a propylene polymer having a melting point of 158 ° C.
(4) PP-4 (propylene / α-olefin random copolymer (E)):
FW4B (trade name) manufactured by Nippon Polypro Co., Ltd., which is a propylene-ethylene-1 butene random copolymer having a melting point of 138 ° C.
(5) PP-5 (propylene / α-olefin random copolymer (E)):
FG4 (trade name) manufactured by Nippon Polypro Co., Ltd., which is a propylene-ethylene random copolymer having a melting point of 143 ° C.
(6) PP-6 (Propylene / α-olefin random copolymer (E)):
WFX4 (trade name) manufactured by Nippon Polypro Co., Ltd., which is a propylene-ethylene random copolymer having a melting point of 125 ° C.
(7) PP-7:
Powder of FW3GT (trade name) manufactured by Nippon Polypro Co., Ltd., which is a propylene-ethylene random copolymer having a melting point of 147 ° C.

(8) PE-1:
Kernel / KS360T (trade name) manufactured by Nippon Polyethylene Corporation
(9) HSBR-1:
Hydrogenated styrene-based elastomer (C): Dynaron 1320P (trade name) manufactured by JSR Corporation

(10) AB-1:
Anti-blocking agent for film (F): Silicia 550 manufactured by Fuji Silysia Co., Ltd. (trade name; average particle diameter of 3.9 μm)
(11) AB-2:
Anti-blocking agent for film (F): Silicia 530 (trade name; average particle size 2.7 μm) manufactured by Fuji Silysia Co., Ltd.
(12) AB-3:
Anti-blocking agent for film (G): Silicia 450 (trade name; average particle size 8.0 μm) manufactured by Fuji Silysia Co., Ltd.
(13) AB-4:
Anti-blocking agent for film (H): Aerosil / TT-600 manufactured by Nippon Aerosil Co., Ltd. (trade name; average particle size 0.04 μm)

[Polymerization Example 1] (Production of PP-1):
(1) Adjustment of olefin polymerization catalyst component In a stainless steel reactor substituted with nitrogen, 360 ml of titanium tetrachloride and 240 ml of toluene were charged to form a mixed solution. Then, a suspension formed by using 120 g of diethoxymagnesium having an average particle size of 42 μm, 500 ml of toluene and 43.2 ml of phthalic acid-di-n-butyl is added to the liquid mixture kept at a liquid temperature of 10 ° C. did. Then, it heated up over 10 minutes from 10 degreeC-90 degreeC, and was made to react, stirring for 2 hours. After completion of the reaction, the obtained solid product was washed four times with 1000 ml of 90 ° C. toluene, and 360 ml of titanium tetrachloride and 800 ml of toluene were newly added, and the temperature was raised to 112 ° C. and reacted while stirring for 2 hours. .
After completion of the reaction, the reaction product was washed 10 times with 1000 ml of n-heptane at 40 ° C. to obtain an olefin polymerization catalyst component. The average particle diameter of the obtained olefin polymerization catalyst component was 42 μm, and the analytical values (by atomic absorption method) were Mg: 18.9 wt%, Ti: 2.2 wt%, Cl: 61.6 wt% Met.

(2) Preactivation treatment of olefin polymerization catalyst component After replacing a stainless steel reactor with an inner volume of 20 liters with inclined blades with nitrogen gas, 17.7 liters of hexane, 100.6 mmol of triethylaluminum, 15.1 mmol of diisopropyldimethoxysilane After adding 120.4 g of the olefin polymerization catalyst component prepared by the above method at room temperature, the mixture was heated to 30 ° C. Next, 240.8 g of propylene was supplied over 3 hours with stirring, and a preliminary activation treatment was performed. As a result of the analysis, 1.9 g of propylene was reacted per 1 g of the olefin polymerization catalyst component.

(3) First polymerization step 0.4 g / hr of an olefin polymerization catalyst component preactivated by the above method in a horizontal polymerization vessel (L / D = 6, internal volume 100 liters) having a stirring blade, organoaluminum compound As triethylaluminum and diisopropyldimethoxysilane as an organosilicon compound were continuously supplied at a molar ratio of Al / Mg molar ratio of 6 and Al / Si molar ratio of 6. A mixed gas of ethylene-propylene is continuously supplied while maintaining the conditions of a reaction temperature of 60 ° C., a reaction pressure of 2.1 MPa, and a stirring speed of 35 rpm, and the ethylene / propylene molar ratio in the gas phase of the reactor is 0.005, hydrogen / Hydrogen gas is continuously supplied from a circulation pipe so as to maintain a propylene molar ratio of 0.007, and the melt flow rate is adjusted by controlling the molecular weight of the ethylene-propylene random copolymer component (a1) as a polymer produced. did.
The reaction heat was removed by the heat of vaporization of the supplied raw material propylene. The unreacted gas discharged from the polymerization vessel was cooled and condensed outside the reactor system through a pipe and refluxed to the polymerization vessel. The ethylene-propylene random copolymer component (a1) obtained by the main polymerization is continuously withdrawn from the polymerization vessel through a pipe so that the retained level of the polymer is 50% by volume of the reaction volume. The polymerization vessel was fed. At this time, a part of the ethylene-propylene random copolymer component (a1) was intermittently extracted from the pipe, and used as a sample for determining the melt flow rate, the ethylene content, and the polymer yield per catalyst unit weight. The ethylene content was measured by infrared absorption spectrum analysis. The polymer yield per catalyst unit weight was measured by inductively coupled plasma emission spectroscopy (ICP method) of Mg content in the polymer.

(4) 2nd polymerization process The ethylene-propylene random copolymer component (a1) and ethylene-propylene-1 from a 1st polymerization process are added to the horizontal type | mold polymerization apparatus (L / D = 6, internal volume 100 liter) which has a stirring blade. -Butene mixed gas was continuously supplied to carry out copolymerization of propylene, ethylene and 1-butene. The reaction conditions were a stirring speed of 25 rpm, a temperature of 55 ° C., a pressure of 1.9 MPa, and a gas phase gas composition of hydrogen / ethylene molar ratio of 0.62, ethylene / propylene molar ratio of 0.14, and 1-butene / propylene molar ratio. Adjusted to 0.06. Carbon monoxide as a polymerization activity inhibitor for adjusting the polymerization amount of the ethylene-propylene-1-butene random copolymer component (a2), and the molecular weight of the ethylene-propylene-1-butene random copolymer component (a2) Hydrogen gas was supplied to control each.
The heat of reaction was removed by the heat of vaporization of the supplied raw material propylene. The unreacted gas discharged from the polymerization vessel was cooled and condensed outside the reactor system through a pipe and refluxed to the second polymerization step. The propylene-based resin composition (A) obtained in the second polymerization step was continuously extracted from the polymerization vessel so that the retained level of the polymer was 50% by volume of the reaction volume. The production rate of the propylene-based resin composition (A) (PP-1) was 8 to 15 kg / hr.
The extracted propylene-based resin composition (A) (PP-1) removes unreacted monomers, and partly contains ethylene polymerized units and 1-butene polymerized units by melt flow rate measurement and infrared absorption spectrum analysis. And the content of the ethylene-propylene-1-butene random copolymer component (a2) by ICP method.
Table 1 shows the polymerization conditions and physical properties of the propylene-based resin composition (A) (PP-1).

[Example 1]
As the self-adhesive layer, intermediate layer, and non-adhesive layer, the components shown in Table 2 were used, and the PP component, the anti-blocking agent component, and the styrenic elastomer component blended in the proportions shown in Table 2 were used as a multilayer. The film is fed to an intermediate layer extruder (60 mm diameter) or two surface layer extruders (30 mm diameter), extruded from a T die at 250 ° C., cooled by a cooling roll at 30 ° C. A sheet was obtained.
In addition, about PP each about 100 weight part, tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane 0.15 weight is used as antioxidant. Parts, calcium stearate as a neutralizer at a ratio of 0.10 parts by weight, and uniformly mixed using a Henschel mixer (trade name), the resulting mixture is melt-kneaded with an extruder and pelletized Used. Moreover, when mixing an antiblocking agent (it also describes as AB agent) component with PP component, it carried out by the said method.
Next, the obtained raw sheet was stretched 5 times in the machine direction (MD) with a heating roll at 110 ° C., and then stretched 8 times in the transverse direction (TD) in a tenter oven at 150 ° C. to prepare a film. .
The obtained film was adjusted to a predetermined test piece, and the initial adhesive strength, adhesive strength with time, total haze, heat resistance, peelability, and testability were measured and evaluated according to a predetermined test method.
The results are shown in Table 2.

[Examples 2 to 8]
A film was prepared in the same manner as in Example 1 except that the component ratios and film thicknesses shown in Table 2 were used.
Table 2 shows the measurement results of the obtained film.

[Comparative Examples 1 to 12 and Reference Example 1]
A film was prepared in the same manner as in Example 1 except that the component ratios shown in Tables 3 and 4 were used.
The results of the measured values of the obtained film are shown in Tables 3 and 4.

Comparing the results of Examples 1 to 8 described in Table 2 above with Comparative Examples 1 to 12 and Reference Example 1 described in Tables 3 and 4 reveals the following.
(1) Examples 1 to 4 are prepared by adjusting the particle size and the amount of the antiblocking agent within the range specified in the present invention on the non-adhesive surface, and Examples 5 and 6 are made of PP. What adjusted melting | fusing point, Furthermore, Example 7 changed the compounding ratio of the adhesion layer, Example 8 changed the compounding ratio of the intermediate | middle layer, but all are haze 8% or less, Excellent peelability (roll feeding, product peeling, etc.) and inspectability, and initial adhesive strength and time-renewed adhesive strength are also within the range specified in the present invention (second invention). It can be seen that there is no occurrence of floating or peeling with respect to the pasting interface.

(2) On the other hand, although Comparative Examples 1-4 changed the kind, particle size, and addition amount of an antiblocking agent different from what was prescribed | regulated by this invention in the non-adhesion layer, haze and roll supply property, It turns out that inspection property etc. are not enough.
(3) In Comparative Examples 5 and 6, a non-adhesive layer having a melting point different from that defined in the present invention was used. It can be seen that it has no appearance.

(4) In Comparative Examples 7, 8, and 10, the pressure-sensitive adhesive layer uses a composition having a pressure-sensitive adhesive layer ratio different from that defined in the present invention. However, if the HSBR is too small, the initial adhesive strength is poor and is too large. It can be seen that product peeling has deteriorated because the renewal adhesive strength with time is too strong. Moreover, although the comparative example 10 uses PE-1 for an adhesion layer, since time-dependent update adhesive strength is too strong, it turns out that roll feeding and product peeling are getting worse.
(5) In Comparative Examples 9 and 11, a composition having an intermediate layer ratio different from that defined in the present invention or a resin composition different from the present invention was used for the intermediate layer. It can be seen that when the blending ratio of the polymer is too large, the film becomes hard and the adhesive layer blending is within the range defined in the present invention, but the initial adhesive strength is lowered. Moreover, in Comparative Example 11, although the resin composition was changed, it was found that the shrinkage after the film was affixed due to the decrease in heat resistance, and the occurrence of lifting and the roll-out property were deteriorated. .

(6) Comparative Example 12 uses a non-adhesive layer with a melting point different from that specified in the present invention, but due to the deterioration of the transparency and appearance of the film, the transparency and appearance sufficient for inspection are obtained. It turns out that it does not have.

(7) In Reference Example 1, 15 wt.% Of propylene homopolymer was used as another resin with respect to the propylene-α-olefin random copolymer (E) having a melting point within the range defined in the present invention in the non-adhesive layer. However, as a result, it is understood that the transparency and appearance of the film are slightly deteriorated, and it cannot be said that the inspection property has sufficient transparency and appearance.

Since the biaxially stretched self-adhesive protective film for in-mold lamination of the present invention has the excellent characteristics as described above, it is used as an alternative to the commonly used protective film as well as more advanced physical properties. Therefore, it can be suitably used for the required applications.

Claims (4)

In the laminated film of at least 3 layers comprised in order of a self-adhesion layer (X) / intermediate layer (Y) / non-adhesion layer (Z), each layer satisfy | fills the requirements of following (i)-(c), Biaxially stretched self-adhesive protective film for in-mold lamination.
(A): The intermediate layer (Y) is a propylene-ethylene random copolymer component (a1) 60 to 70 wt% containing propylene units in the range of 98 to 99.9 wt% based on the weight of the copolymer (a1). Propylene resin composition comprising 30 to 40% by weight of a propylene / α-olefin random copolymer component (a2) containing propylene units in the range of 70 to 80% by weight based on the weight of the copolymer (a2) A) 30 to 100% by weight and propylene homopolymer (B) 0 to 70% by weight.
[However, the melt flow rate (MFR _a2 ) of the propylene / α-olefin random copolymer component (a2) is in the range of 4.0 to 15.0 g / 10 min, and the propylene-ethylene random copolymer component (a1) in the melt flow rate range of the ratio _(MFR a2 / MFR _a1) is 3.0 to 15.0 in melt flow rate of the propylene · alpha-olefin random copolymer component to the _{(MFR a1) (a2) (} MFR a2) is there. ]
(B): The self-adhesive layer (X) comprises 55 to 70% by weight of a hydrogenated styrene elastomer (C) and 30 to 45% by weight of a propylene homopolymer (D).
(C): Non-adhesive layer (Z) is blended with 0.5 to 1.5 parts by weight of anti-blocking agent for film (F) with respect to 100 parts by weight of propylene / α-olefin random copolymer (E). It consists of a polymer composition.
[However, the propylene / α-olefin random copolymer (E) is a propylene-ethylene random copolymer or propylene-ethylene-1 butene random copolymer having a melting point of 125 to 145 ° C. The anti-blocking agent (F) has an average particle diameter measured by a laser diffraction method of 1.0 to 5.0 μm. ]   This is an adhesive strength measurement method based on the adhesive strength measurement method specified in JIS Z0237 (2000) (held at 23 ° C. and 50 RH% for 24 hours), and the holding conditions are maintained at 23 ° C. and 50% RH for 30 minutes. 2. The biaxially stretched self-adhesive protective film for in-mold lamination according to claim 1, wherein the adhesive strength (initial adhesive strength) when held is 3 g / 25 mm or more.   The biaxially stretched self-adhesive protective film for in-mold lamination according to claim 1 or 2, wherein the film has a haze of 8% or less as measured in accordance with JIS K7105 (1981).   The biaxially stretched self-adhesive protective film for in-mold lamination according to any one of claims 1 to 3, wherein the self-adhesive layer (X) does not contain a tackifier.