JP4452542B2 - Resin composition and moisture-proof paper using the same - Google Patents

Description

  The present invention relates to a resin composition, in particular, a resin composition excellent in moisture resistance and a moisture-proof paper using the resin composition, particularly excellent in moisture resistance of a bent portion and recyclable.

  Dampproof paper is widely known as a packaging material for liquid or solid contents. Such moisture-proof paper is obtained by coating the base paper mainly with polyolefin such as polyethylene, polypropylene, polybutylene and the like. However, moisture-proof paper coated with such a simple material cannot satisfy the recent demand for recycling because the strength of the coat layer (moisture-proof layer) is too strong. Thus, various resin compositions have been proposed as moisture-proof processing resins that can meet the demand for recycling.

For example, a resin composition comprising an amorphous (atactic) polypropylene having a weight average molecular weight Mw of 10,000 to 100,000, a tackifier resin, a wax, and a styrene-based elastomer has been proposed (for example, see Patent Document 1). A resin composition comprising 1,000 to 100,000 attack polypropylenes and a tackifier has been proposed (see, for example, Patent Document 2). When these resin compositions are coated on a paper base material, the moisture resistance and recyclability of the resulting processed paper are once satisfied.
However, when such moisture-proof paper is used for packaging, it is often accompanied by a folding process. In this case, the coating layer made of these resin compositions cannot sufficiently withstand the folding process, and the folded part The problem is that cracks occur and the moisture resistance is reduced.
JP-A 64-26688 JP-A-9-316252

  In view of such circumstances, the present invention provides a resin composition that is easy to coat on a paper substrate, and that the resulting moisture-proof paper is excellent in recyclability and also has excellent moisture resistance in the bent portion. is there.

  Claim 1 of this invention for solving the said subject is (A) Amorphous polyolefin 40-74.5 weight part with a weight average molecular weight (Mw) 15,000-200,000, (B) Tackifier 25- 59.5 parts by weight and (C) 0.5 to 30 parts by weight of a high molecular weight amorphous polyolefin having a weight average molecular weight (Mw) of 250,000 to 2 million [100 in total of (A), (B) and (C) The content is a resin composition characterized by comprising:

  Claim 2 of the present invention further includes (D) a resin composition in which 0.5 to 20 parts by weight of wax is added to 100 parts by weight of the resin composition.

  Claim 3 of the present invention contains the resin composition according to claim 1 or 2, wherein the high molecular weight amorphous polyolefin (C) is an amorphous polypropylene having a weight average molecular weight (Mw) of 600,000 to 1,500,000. And

According to a fourth aspect of the present invention, the amorphous polyolefin (A) comprises 80 to 99% by weight of the amorphous polypropylene (a1) and 1 to 20% by weight of the amorphous ethylene / propylene copolymer (a2). Item 1 is a resin composition according to item 1 .

  Claim 5 of the present invention is for moisture proof, and contains the resin composition according to any one of claims 1 to 4.

  According to a sixth aspect of the present invention, the moisture-proof paper is characterized in that a resin layer comprising the resin composition according to any one of the first to fifth aspects is provided on at least one surface of the paper substrate. To do.

  A seventh aspect of the present invention includes the moisture-proof paper according to the sixth aspect in which an acrylic resin layer is provided on the resin layer.

  The resin composition of the present invention comprises (A) 40 to 74.5 parts by weight of an amorphous polyolefin having a weight average molecular weight (Mw) of 15,000 to 200,000, (B) 25 to 59.5 parts by weight of a tackifier, and ( C) A resin composition comprising 0.5 to 30 parts by weight of a polymer amorphous polyolefin having a weight average molecular weight (Mw) of 250,000 to 2 million, and in particular, a moisture-proof paper coated with the resin composition is bent. Also, the moisture-proof paper has an excellent moisture-proof property, and the moisture-proof paper has good disintegration by the pulper, and the moisture-proof paper can be recycled.

The amorphous polyolefin (A) used in the present invention is an amorphous polyolefin-based polymer, and is a homopolymer of propylene or a random or block copolymer of propylene and a small amount of α-olefin. Examples of the α-olefin include C _{2 and} C ₄ to ₁₂ , preferably C ₂ ethylene. When the amorphous polyolefin is a random copolymer, the proportion of α-olefin, which is another copolymer component of the copolymer, is generally 10% by weight or less, preferably 0.5 to 7% by weight. In the case of a block copolymer, the proportion of α-olefin which is another copolymer component of the copolymer is generally 1 to 40% by weight, preferably 1 to 25% by weight, more preferably 2 to 2% by weight. 20% by weight. Two or more of these amorphous polyolefins may be used in combination. As an index of crystallinity of the amorphous polyolefin, for example, a melting point, a heat of crystal fusion, and the like are used. The melting point is preferably 120 to 176 ° C. and the heat of crystal fusion is preferably in the range of 60 to 120 J / g. If the melting point or heat of fusion of the crystal is too low, the heat resistance of the material will be poor.

  Amorphous polyolefin (A) is essentially amorphous in terms of physical properties such as viscosity and impact resistance of the resin composition, and has a weight average molecular weight (Mw) of 15,000 to 200,000. Must be in range. Particularly preferred is 30,000 to 100,000. If the weight average molecular weight (Mw) is less than 15,000, due to insufficient heat resistance, smearing occurs on the recycled paper. On the other hand, if it exceeds 200,000, poor coating due to thickening of the coating liquid occurs.

As a method for producing the amorphous polyolefin (A), generally, a Ziegler-Natta type catalyst using a combination of a so-called titanium-containing transition metal component and an organometallic component is used. In particular, the transition metal component is an essential component of titanium, magnesium, and halogen, the solid component or titanium trichloride having an electron donating compound as an optional component, and a catalyst in which the organic metal component is an aluminum compound, slurry polymerization, gas Phase polymerization, bulk polymerization, solution polymerization, or a polymerization method combining these, in one stage or two or more stages, propylene alone, or propylene and C ₂ or C ₄ to ₁₂ α-olefin, preferably C ₂ It can be obtained by copolymerizing ethylene. Moreover, a corresponding commercial item can be used.

  Specific examples of the commercially available amorphous polyolefin (A) include Tuffmer P-0480 (ethylene-α-olefin copolymer), P-0280 (ethylene-α-olefin copolymer), Degussa from Mitsui Chemicals, Inc. Bestplast 703 (Mw 34,000), 828 (Mw 61,000), East Bond G-92 (Mw 18,000) manufactured by Eastman Chemical Products, East Bond M5F (Mw 23,000-25,000) ), RT B3A15 (Mw 28,000) manufactured by Elvaso Products. These may be used alone or in combination of two or more. Among these, amorphous polypropylene homopolymer and amorphous ethylene / propylene copolymer are particularly excellent in terms of moisture resistance of the present invention. In particular, the combined use of (a1) amorphous polypropylene and (a2) amorphous ethylene / propylene copolymer is preferable because flexibility is imparted and moisture resistance of the bent portion is excellent. The ratio of (a1) and (a2) is preferably (a1) 80 to 99% by weight and (a2) 1 to 20% by weight.

The tackifier (B) used in the present invention is also called tackifier. Examples of the compound containing a functional group in the molecule or a mixture containing the compound include rosin, modified rosin and ester compounds thereof, alkylphenol resin, alkylphenol modified xylene resin, rosin modified xylene resin, terpene phenol resin, and the like. Examples of terpene resins that do not contain terpene resins and aromatic modified terpene resins include terpene resins, olefin resins, styrene resins, petroleum resins, hydrogenated petroleum resins, and coumarone indene resins. These may be used alone or in combination of two or more. Of these, aromatic and aliphatic resins, terpene phenol resins, aromatic modified terpene resins, rosin esters, etc., are compatible with polyolefin resins and become a substantially transparent solution when dissolved at high temperatures. Is preferred. Furthermore, hydrogenated aliphatic petroleum resins, hydrogenated terpene resins, and hydrogenated rosin esters are particularly suitable for food packaging.
The usage-amount of a tackifier is 25-59.5 weight part, Preferably, it is 28-45 weight part. If the amount is less than 25 parts by weight, the disaggregation property is insufficient, and if it exceeds 59.5 parts by weight, the moisture resistance of the bent portion is lowered. This is because the processed layer processed using the resin composition becomes brittle and easily cracks.

The high molecular weight amorphous polyolefin (C) used in the present invention has a weight average molecular weight (Mw) of 250,000 to 2,000,000, preferably 600,000 to 1,500,000. When the weight average molecular weight (Mw) is lower than 250,000, the moisture resistance of the moisture-proof paper processed with the resin composition of the present invention, particularly the bent portion, tends to be lowered. Becomes worse. The high molecular weight amorphous polyolefin (C) is preferably an amorphous polypropylene type having an n-hexane insoluble content at a temperature of 25 ° C. of 5% by weight or less, more preferably 2% by weight or less, and further preferably 1% by weight or less. Among them, a polypropylene homopolymer is preferable. As the amount of n-hexane insoluble matter increases, the flexibility decreases. More preferably, an amorphous polypropylene having an n-hexane insoluble content at a temperature of 25 ° C. of 5% by weight or less and having neither a crystal melting peak nor a crystallization peak as measured by a differential scanning calorimeter (DSC) preferable. Those having a crystal melting peak or a crystallization peak have insufficient flexibility.
High molecular weight amorphous polyolefins satisfying such characteristic (C) is typically obtained using meta Rose emissions catalyst, as corresponding commercial products, Sumitomo Chemical Tafuse Les emission Corporation (TM) T3712 (Crystalline PP 15% added product), T3722 (crystalline PP 30% added product) and the like. These may be used alone or in combination of two or more.

In addition, the measuring method of n-hexane insoluble matter is as follows.
The sample is cut into a size of about 1 mm square, and about 0.5 g is accurately weighed to obtain Xg. Place the weighed sample in a conical flask with a stopper, add 250 ml of n-hexane solvent containing 0.1% by weight of antioxidant (Sumilyzer BHT), soak it in a thermostatic bath at 25 ° C., and leave it for 24 hours. Place the flask on a shaker and shake at 120 rpm for 1 hour. A 120 mesh wire mesh is prepared and weighed accurately to obtain Yg. The sample solution shaken using this wire mesh is filtered. The filtered wire mesh is dried at 80 ° C. for 3 hours in a vacuum dryer, and the total weight of the wire mesh and the sample insoluble matter remaining therein is accurately weighed to obtain Zg. The n-hexane insoluble matter was determined by the following formula.
n-hexane insoluble matter (% by weight) = 100 × (ZY) / X

  The weight average molecular weight Mw of the amorphous polyolefin (A) and the high molecular weight amorphous polyolefin (C) can be measured by a gel permeation chromatography (GPC) method.

  A wax (D) is added to the resin composition of the present invention as necessary. As the wax (D) used in the present invention, known waxes used for hot melt adhesives and the like can be used. For example, low molecular weight polyethylene, polypropylene degradable wax, microcrystalline wax, Fischer-Tropsch wax, paraffin wax and the like can be mentioned. These may be used alone or in combination of two or more. It is preferable that the usage-amount of the wax in a composition is 0.5-20 weight part from the point of the viscosity which affects the hardening time of a composition, operativity, and adhesiveness. 5 to 17 parts by weight is particularly preferable.

  To the resin composition of the present invention, an antioxidant, an adhesion regulator, a lubricant and the like can be added to further improve processability, and an antiblocking agent and an antistatic agent can be added to improve the properties of the processed paper.

An excellent moisture-proof paper can be obtained by applying the resin composition of the present invention to at least one surface of a paper substrate. The amount of the resin composition to be applied may be adjusted according to the desired moisture resistance, but usually about 10 to 50 g / m ² is employed. Preferably it is 16-25 g / m < ² >. As a coating method of the resin composition of the present invention, a coating method using a coater such as a roll coater, a slot orifice coater or an extrusion coater, an extrusion laminating method using a die such as a T die, or the like can be adopted.

  By providing an overcoat layer made of an acrylic resin layer on the moisture-proof paper resin layer, the moisture-proof paper is improved in blocking, the quality maintenance performance of the packaging content is improved, and the packaging content of the resin composition component It is possible to improve the prevention of transition to.

As the acrylic resin used in the present invention, a copolymer resin of (meth) acrylic acid methyl and (meth) acrylic acid, (meth) acrylic acid ester other than methacrylmethyl or styrene is preferably used. These may be used alone or in combination of two or more. The resin may be in the form of a solution dissolved in a solvent, or in the form of an emulsion dispersed in a liquid such as water. If the main component is an acrylic resin, an SBR rubber latex or the like can be used in combination. Further, for example, an inorganic filler as an anti-slip agent, a small amount of wax as an anti-blocking agent, an antistatic agent for removing static electricity, a coloring agent, and the like can be appropriately added to the acrylic resin.
The acrylic resin is applied with various coaters as described above, and then the solvent is removed by drying to form an overcoat layer. The thickness of the overcoat layer is preferably from 0.1 to 3 g / m ² . If it is less than 0.1 g / m ² , the effect of providing an overcoat layer is not sufficient. On the other hand, if it exceeds 3 g / m ² , a further effect of the overcoat layer cannot be expected, which is uneconomical.

The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited thereto.
In the following examples and comparative examples, the evaluation method of characteristics was performed as follows.

(1) Disaggregation property Using a standard pulp disaggregator manufactured by Kumagai Riki Kogyo Co., Ltd., 40 g of a moisture-proof paper sample cut to 1 to 1.5 cm square is put into 2 liters of water and about 2% by weight of moisture-proof paper is dispersed in water. The liquid was stirred for 30 minutes, then paper was made, and the dispersibility of the resin component was judged visually by the following criteria.
○: The presence of the resin component is hardly confirmed in the paper made.
X: The resin component which is not disperse | distributed many adheres and exists in paper-made paper.

(2) Moisture permeability
The measurement was performed according to the cup method specified in JIS Z 0208. As a folding process of the moisture-proof paper sample before the measurement of moisture permeability, two types of folding, a reverse cross fold and a corner fold, were performed. When the sample was mounted on the cup, the moisture permeability was measured with the moisture-proof surface on the inside and the paper surface on the outside.
Inverse cross-folding is performed by bending the sample side to the outside (mountain fold) and reciprocating once on the line of the crease line with a 2 kg roller, and then spreading it once and bending it vertically with the processing side to the outside ( Mountain fold), the fold was reciprocated once by a 2 kg roller, and then the sample was spread and its moisture permeability was measured.
The corner fold is made by folding the sample with the non-processed surface (paper surface) on the outside and bending it sideways (valley fold) once on the crease line with a 2 kg roller, then folding it sideways and folding it vertically to fold line. 1 roll back and forth with a 2 kg roller, and further spread the sample, with the processing surface outside, and fold it again at the intersection of the previous horizontal and vertical folds at the diagonal line that intersects the crease line at 45 degrees, and on the crease line Was reciprocated once with a 2 kg roller, and then the sample was spread and its moisture permeability was measured.

Example 1
Amorphous polypropylene homopolymer (RT2180A, DSC chart FIGS. 1 and 2, weight average molecular weight Mw 71,000, manufactured by Huntsman) 47.2 parts by weight, amorphous ethylene / propylene copolymer (RT2280A, weight average molecular weight Mw 6. 90,000, manufactured by Huntsman) 5.5 parts by weight, terpene phenol resin tackifier (Polystar T160, manufactured by Yashara Chemical Co., Ltd.) 40 parts by weight, polypropylene degradable wax (High Wax NP500, manufactured by Mitsui Chemicals) 12.0 parts by weight Part, high molecular weight amorphous polypropylene (Tuff Selenium T3712, DSC chart of amorphous component, FIG. 3 and FIG. 4, n-hexane insoluble content of amorphous component at a temperature of 25 ° C. is 1% by weight or less, weight average molecular weight Mw 700,000 to 800,000, manufactured by Sumitomo Chemical Co., Ltd.) 8.6 parts by weight (7.3 parts by weight as high molecular weight amorphous polypropylene) and antioxidants (Antage DAH, Kawaguchi Chemical) The Ltd.) 0.3 part by weight was heated to about 200 to 220 ° C. in a container, after these ingredients are melted, stirred thoroughly so that each component is uniformly dispersed to prepare a resin composition.
The obtained using Meyer bar had been preheated resin composition was coated at a thickness of about 20 g / m ² in the Kraft paper 75 g / m ² to obtain a formed moistureproof paper a resin layer. The obtained moisture-proof paper was characterized by the above method, and the results are shown in Table 1.

Example 2
On the moisture-proof paper resin layer prepared in Example 1, styrene-acrylic resin EK-61 (Syden Chemical Co., Ltd.) 26 parts by weight of water / isopropanol (53:47) and hollow beads AK-850 (JSR Corporation) 19.5 parts by weight, 0.3% by weight of antifoaming agent Surfinol (manufactured by Nissin Chemical Industry Co., Ltd.) and 9.5 parts by weight of 20% aqueous solution of polyvinyl alcohol KM-11 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) The obtained mixture having a solid content concentration of 19% by weight was applied in a wet state to 6.5 g / m ² and dried at 100 ° C. for 1 minute to form an overcoat layer. The obtained moisture-proof paper was characterized by the above method, and the results are shown in Table 1.

Example 3
Amorphous polypropylene homopolymer (RT2180A, DSC chart Fig. 1 and Fig. 2, weight average molecular weight Mw 71,000, manufactured by Huntsman) 48.5 parts by weight, terpene phenol resin tackifier (Polystar T160, manufactured by Yasuhara Chemical Co., Ltd.) ) 45.0 parts by weight and high molecular weight amorphous polypropylene (Tufselen T3712, DSC chart of amorphous component FIGS. 3 and 4, n-hexane insoluble content of 1% by weight or less of amorphous component at a temperature of 25 ° C., weight average molecular weight Mw 700,000 to 800,000, manufactured by Sumitomo Chemical Co., Ltd.) 7.6 parts by weight (6.5 parts by weight as high molecular weight amorphous polypropylene) and 0.3 parts by weight of antioxidant (Antage DAH, manufactured by Kawaguchi Chemical Co., Ltd.) After heating to about 200-220 degreeC and these components fuse | melted, it stirred enough so that each component might disperse | distribute uniformly, and created the resin composition.
The obtained using Meyer bar had been preheated resin composition was coated at a thickness of about 20 g / m ² in the Kraft paper 75 g / m ² to obtain a formed moistureproof paper a resin layer. Further, an overcoat layer was provided on the processed surface of the obtained moisture-proof paper using styrene / acrylic resin EK-61 in the same manner as in Example 2. The properties of the obtained moisture-proof paper were evaluated by the method described above, and the results are shown in Table 1.

Comparative Example 1
The same components as in Example 1, except that high molecular weight amorphous polypropylene (Tufselen T3712, manufactured by Sumitomo Chemical Co., Ltd.) 8.6 parts by weight of crystalline polypropylene resin (J107G, molecular weight 220,000, manufactured by Mitsui Chemicals, Inc.) A moisture-proof paper was obtained in the same manner as in Example 1, using 3.65 parts by weight and 3.65 parts by weight of hydrogenated styrene butadiene rubber (Dynalon 1321P, manufactured by JSR Corporation). The obtained moisture-proof paper was similarly evaluated for properties, and the results are shown in Table 1.

Comparative Example 2
On the resin coating layer of the moisture-proof paper prepared in Comparative Example 1, overcoating was performed in the same manner as in Example 2 using styrene acrylic resin EK-61 (manufactured by Seiden Chemical Co., Ltd.). The obtained moisture-proof paper was characterized by the above method, and the results are shown in Table 1.

Comparative Example 3
Amorphous polypropylene homopolymer (RT2180A, DSC chart FIGS. 1 and 2, weight average molecular weight Mw 71,000, manufactured by Huntsman) 54.4 parts by weight, amorphous ethylene / propylene copolymer (RT2280A, weight average molecular weight Mw 6. 90,000, manufactured by Huntsman) 5.5 parts by weight, terpene phenol resin tackifier (Polystar T160, manufactured by Yashara Chemical Co., Ltd.) 28.8 parts by weight, polypropylene degradable wax (High Wax NP500, manufactured by Mitsui Chemicals) 20.0 parts by weight Parts, crystalline polypropylene resin (J107G, molecular weight 220,000, manufactured by Mitsui Chemicals) 7.65 parts by weight and hydrogenated styrene butadiene rubber (Dynalon 1321P, manufactured by JSR Corporation) 3.65 parts by weight and antioxidant (ANTAGE DAH, Kawaguchi Chemical) (Made by Kogyo Co., Ltd.) Put 0.3 parts by weight in a container and heat to about 200-220 ° C. After these components melt, Thoroughly agitated so as to disperse one to prepare a resin composition.
The obtained using Meyer bar had been preheated resin composition was coated at a thickness of about 20 g / m ² in the Kraft paper 75 g / m ² to obtain a formed moistureproof paper a resin layer. Further, overcoating was performed on the obtained coating layer in the same manner as in Example 2 using styrene / acrylic resin EK-61 (manufactured by Seiden Chemical Co., Ltd.). The properties of the obtained moisture-proof paper were evaluated by the method described above, and the results are shown in Table 1.

  As is clear from the results in Table 1 above, the resin composition of the present invention drastically improves the moisture permeability both after the reverse cross-folding and after the corner folding by blending the high molecular weight amorphous polyolefin (C). It can be seen that the moisture-proof performance is excellent.

  As described above, when the resin composition of the present invention is applied to, for example, a paper base material, it exhibits excellent moisture resistance even in a portion subjected to bending processing, and is excellent in disaggregation, A moisture-proof paper with good recyclability can be provided.

RT2180A DSC chart (Mp) RT2180A DSC chart (Tg) DSC chart of amorphous component of Tough Selenium T3712 (Mp) DSC chart of amorphous component of Tough Selenium T3712 (Tg)

Claims (7)

  (A) 40-74.5 parts by weight of an amorphous polyolefin having a weight average molecular weight (Mw) of 15,000 to 200,000, (B) 25-59.5 parts by weight of a tackifier, and (C) a weight average molecular weight (Mw). A resin composition comprising 0.5 to 30 parts by weight of a high molecular weight amorphous polyolefin of 250,000 to 2 million [100 parts by weight in total of (A), (B) and (C)].   Furthermore, (D) The resin composition formed by adding 0.5 to 20 parts by weight of wax to 100 parts by weight of the resin composition.   The resin composition according to claim 1 or 2, wherein the high molecular weight amorphous polyolefin (C) is an amorphous polypropylene having a weight average molecular weight (Mw) of 600,000 to 1,500,000. The resin composition according to claim 1, wherein the amorphous polyolefin (A) comprises 80 to 99% by weight of amorphous polypropylene (a1) and 1 to 20% by weight of amorphous ethylene / propylene copolymer (a2) .   The resin composition according to any one of claims 1 to 4, which is used for moisture prevention.   A moisture-proof paper comprising a resin layer comprising the resin composition according to any one of claims 1 to 5 on at least one surface of a paper substrate. The moisture-proof paper according to claim 6, wherein an acrylic resin layer is provided on the resin layer.

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