JP5826603B2 - Improved composition for sealing material and method for producing the same - Google Patents

Description

  The present invention relates to a composition for a sealing material containing polybutene and a method for producing the same. More specifically, the present invention relates to a composition for a sealing material which is composed of components of polybutene, polyethylene and hydrocarbon resin, and suppresses bleed-out of polybutene and a method for producing the same.

A sealing material containing polybutene has excellent alkali resistance and high adhesion, and can be applied to the surface of various members to form a seal excellent in workability, heat resistance and sealing performance.
As an applicable sealing material, for example, in an alkaline battery, a sealing material is used for a sealing portion in order to prevent a leakage phenomenon caused by a creep phenomenon of an alkaline electrolyte or generation of hydrogen gas due to discharge. Also for manganese dry batteries, a sealing material is used for the sealing portion in order to maintain the confidentiality of the sealing portion and prevent the ingress of oxygen and the leakage of the electrolyte.

  The present inventors have already mainly used polybutene having a number average molecular weight of 700 to 10,000 containing 0.5 to 10% by weight of crystalline polypropylene as a sealable material that seals the gap between the battery sealing portions. A sealing material made of a polymer has been proposed (Patent Document 1: Japanese Patent Laid-Open No. 62-154556).

In addition, by applying optical concealability to the sealable material, the design of the product is improved, and the efficiency of the macroscopic and optical inspection process is improved by easily identifying the seal part. I came.
In order to solve the above problems, the present inventors have prepared a dispersion medium composed of 98 to 80 parts by mass of polybutene and 2 to 20 parts by mass of polyethylene having a density of 0.93 g / cm ³ or less (100 parts by mass of both), and It has been proposed to use a composition comprising 0.1 to 10 parts by weight of an inorganic pigment dispersed therein as a composition for a sealing material (Patent Document 2: JP-A No. 2003-268293). Among them, it is disclosed that the polybutene used has a number average molecular weight of 700 to 10,000. Furthermore, the present inventors have proposed that a composition for a sealing material excellent in coating workability and heat resistance can be obtained by limiting the number average molecular weight to 1000 to 2500 (Patent Document 3: Japanese Patent Application Laid-Open No. 2009-2009). 221421).

  Further, in recent years, demands for use in more severe environments are increasing due to demands for increasing the capacity of batteries, environment or energy saving. Under these circumstances, there is a demand for improvement in durability of a sealing material containing polybutene, more specifically, suppression of bleeding of the polybutene component together with confidentiality. For that purpose, the present inventors have examined the compatibility of polybutene and polyethylene, and as a result, it has been found that the use of polybutene having a number average molecular weight of more than 1200 alone in the composition of Patent Document 2 tends to cause bleeding. It was.

Japanese Patent Laid-Open No. 62-154556 JP 2003-268293 A JP 2009-22214 A

  The subject of this invention is providing the composition for sealing materials which was excellent in the sealing performance and the applicability | paintability which suppressed the bleed | bleed by improving the compatibility of polybutene and polyethylene. Furthermore, by uniformizing and stabilizing the dispersion state of the inorganic pigment in the polyolefin-based dispersion medium, in addition to the above-described design properties and / or compatibility with the inspection process, in addition to sealing properties and coating properties, It is providing the composition for sealing materials excellent in concealing property.

As a result of intensive studies by the present inventors, it has been found that the separation of the polybutene component from the composition for a sealing material can be accurately evaluated by conducting an oil separation test which is an oil separation test of grease. Furthermore, the quantitative evaluation method of the bleed-out of polybutene was established by setting the test conditions to 45 ° C. for 2 weeks. Furthermore, by setting the test conditions to 60 ° C. for one week, an evaluation method under more severe bleed conditions was established. As a result, in the composition of Patent Document 2, when a polybutene having a number average molecular weight of more than 1200 is used alone, it seems to be derived from poor compatibility between the polybutene and polyethylene, but it tends to bleed, It turns out that there is a problem in use.
Then, when investigation was advanced for the purpose of further improving compatibility, it turned out that polybutene becomes difficult to bleed by mix | blending a hydrocarbon resin. This effect is presumed to be due to the further improved compatibility between polybutene and polyethylene.

That is, the present invention comprises (a) 2 to 20 parts by mass of polyethylene having a density of 0.916 to 0.930 g / cm ³ and MFR4 or more, (b) 98 to 80 parts by mass of polybutene having a number average molecular weight of 700 to 10,000, and (C) 2-20 parts by mass of a hydrocarbon resin (the total of (a), (b) and (c) is 100 parts by mass), and the degree of oil separation at 60 ° C. is 0.1% or less in one week It is related with the composition for sealing materials which is.

  Moreover, this invention relates to the said composition for sealing materials whose said (c) hydrocarbon resin is an alicyclic hydrocarbon resin and / or an aliphatic hydrocarbon resin.

  Moreover, this invention relates to the said composition for sealing materials formed by making 100 mass parts of said compositions for sealing materials into a dispersing agent, and dispersing 0.1-10 mass parts of inorganic pigments.

The present invention also includes (a) 2-20 parts by mass of polyethylene having a density of 0.916 to 0.930 g / cm ³ and MFR4 or higher, (b) 98-80 parts by mass of polybutene having a number average molecular weight of 700 to 10,000, and (C) After mixing a composition comprising 2 to 20 parts by mass of a hydrocarbon resin (the total of (a), (b) and (c) is 100 parts by mass) at 120 to 200 ° C., 1 ° C./min It is related with the manufacturing method of the composition for sealing materials whose oil separation degree in 60 degreeC characterized by cooling with the above cooling rate is 0.1% or less in one week.

  The present invention also relates to (c) the method for producing the sealing material composition, wherein the hydrocarbon resin is an alicyclic hydrocarbon resin and / or an aliphatic hydrocarbon resin.

Since the compatibility of polybutene and polyethylene is further improved in the composition for sealing material of the present invention, bleed-out of polybutene is suppressed. Therefore, by using the composition for a sealing material of the present invention, a highly reliable sealing film is obtained in which the composition for a sealing material does not flow out or peel off from the application site and the light component does not bleed.
Moreover, the presence or absence of the coating agent of an application location can be easily confirmed by disperse | distributing an inorganic pigment to the composition for sealing materials. As a result, it is possible to easily inspect the application state visually and optically at the time of assembling the product, thereby improving the work efficiency and reliability of the assembly process.

  The present invention will be described below.

The polyethylene having a density of 0.916 to 0.930 g / cm ³ and an MFR of 4 or more used as the component (a) in the composition for a sealing material of the present invention mainly has a shape retaining property at the time of sealing, and a dispersion medium of an inorganic pigment. Involved in uniform dispersibility and anti-sedimentation properties. Polyethylene having a density of 0.916 to 0.930 g / cm ³ is excellent in compatibility with polybutene because it contains many amorphous parts, and since it contains many branches, the dispersion state of the inorganic pigment is made uniform, and It is considered that the stabilizing effect is great. While density is required to be 0.916~0.930g / cm ^3, preferably a density 0.918~0.930g / cm ^3, more preferably a density 0.920~0.930g / cm ³ is there. Polyethylene having a density exceeding 0.930 g / cm ³ is not preferable because the amorphous part is reduced and the compatibility with polybutene is deteriorated. On the other hand, when the density is less than 0.916 g / cm ³ , there are practical problems such as an increase in fluidity of the resulting sealing material composition.

Among polyethylenes having a density of 0.916 to 0.930 g / cm ³ , those having a melting point (JIS-K-7121) measured by DSC of 120 ° C. or less are preferable, and polyethylene having a non-crystalline part, amorphous High-pressure polyethylene having many parts and containing many long-chain branches, or polyethylene having an MFR (180 ° C./2.16 kg load (JIS-K-6760)) of 5 to 25 excellent in compatibility with polybutene is preferred. The polyethylene may be a copolymer of ethylene and another olefin (for example, ethylene and another α-olefin) or a copolymer of vinyl acetate, acrylic acid, acrylate ester, or the like. However, in these copolymers, if the content of the polar monomer is high, it becomes difficult to be compatible with polybutene. Therefore, it is necessary to select the copolymer within a range compatible with polybutene. These polyethylenes may be used alone or in combination of two or more.

  In the composition for a sealing material of the present invention, the component (a) needs to be contained in an amount of 2 to 20 parts by mass in 100 parts by mass of a dispersion medium (composition composed of polybutene, polyethylene and hydrocarbon resin). When the amount is less than 2 parts by mass, there is no effect of adding polyethylene, and it becomes difficult to maintain shape retention. When the amount exceeds 20 parts by mass, the viscosity of the resulting sealing material composition is too high, and the application work to the adherend It becomes difficult.

In the composition for a sealing material of the present invention, polybutene having a number average molecular weight of 700 to 10,000 is used as the component (b).
Polybutene is a polymer obtained by polymerizing isobutene as a main monomer, and includes a homopolymer of isobutene or a copolymer of isobutene and n-butene. Polybutene having a number average molecular weight in the range of 700 to 10000 can be easily obtained from the market (for example, JX Nippon Mining & Energy Co., Ltd .: Nisseki Polybutene).
Any product obtained by a known production method can be used as long as the number average molecular weight is in the above range. Polybutene is mainly involved in fluidity when shear stress is applied to the dispersion medium and shape retention in a sealed state.

  The number average molecular weight of the polybutene as the component (b) needs to be 700 or more and 10,000 or less. It is desirably 800 or more and 3500 or less, and more desirably 900 or more and 2500 or less. When the number average molecular weight of the polybutene as the component (b) is less than 700, the resulting composition for sealing material has a problem in heat resistance, and the polybutene bleeds from the coating film at a low temperature and cannot be used. In addition, the melt viscosity becomes too low, causing a problem in coating workability. On the other hand, when the number average molecular weight exceeds 10,000, the resulting coating concealing composition has a melt viscosity that is too high to make it difficult to apply to the adherend. Polybutenes may be used alone or in combination of two or more.

  The polybutene as the component (b) needs to be contained in 98 to 80 parts by mass in 100 parts by mass of the dispersion medium (composition composed of polybutene, polyethylene and hydrocarbon resin). If it is less than 80 mass parts, the viscosity of the composition for sealing materials obtained is too high, and the workability of application to the adherend becomes difficult. On the other hand, if the amount exceeds 98 parts by mass, the effect of adding polyethylene is lost, and it is difficult to maintain shape retention, which is not preferable.

  In the composition for sealing materials of the present invention, a hydrocarbon resin is used as the component (c). By blending the hydrocarbon resin, the compatibility of polybutene and polyethylene is improved, and a composition for sealing material in which bleeding of polybutene is suppressed can be obtained. When a composition for a sealing material is produced without using a hydrocarbon resin, the bleed of polybutene is large and sufficient sealing performance cannot be obtained.

The hydrocarbon resin is obtained by polymerizing an unsaturated hydrocarbon-containing fraction obtained at the time of cracking and refining petroleum in the presence of a Friedel-Crafts catalyst. As the hydrocarbon resin obtained by this method, an aliphatic hydrocarbon resin obtained by polymerizing an unsaturated hydrocarbon-containing fraction having a boiling range of −20 ° C. to −100 ° C., a boiling range of 140 ° C. to 280 ° C. Aromatic hydrocarbon resins obtained by polymerizing unsaturated aromatic hydrocarbon-containing fractions, aliphatic aromatic copolymer hydrocarbon resins obtained by copolymerizing both unsaturated hydrocarbon-containing fractions, and aliphatic Heat treatment of the unsaturated hydrocarbon-containing fraction to cyclize and dimerize dienes or cyclodienes, for example, alicyclic hydrocarbon resins obtained by polymerization after conversion to dicyclopentadiene It is done.
In the present invention, as the (c) component hydrocarbon resin, an alicyclic hydrocarbon resin and / or an aliphatic hydrocarbon resin is preferably used. As the alicyclic hydrocarbon resin, a resin obtained by polymerizing an alicyclic olefin compound such as cyclopentadiene or alkylcyclopentadiene using an acid catalyst, or an alkenyl aromatic hydrocarbon is polymerized using an acid catalyst. Then, a resin obtained by nuclear hydrogenation of an aromatic ring can be used. These alicyclic hydrocarbon resins are commercially available, for example, under the trade name Escorez 5300 (manufactured by Exxon Mobil Chemical).
As the component (c), a hydrocarbon resin having a softening point of 90 to 110 ° C. is preferably used. When the softening point is too low, the flow resistance is inferior, which is not preferable. When the softening point is too high, the melt viscosity becomes too high, causing a problem in handling.

  In the composition for a sealing material of the present invention, the blending ratio of the hydrocarbon resin as the component (c) is 2 to 20 parts by mass in 100 parts by mass of the whole composition (composition composed of polybutene, polyethylene and hydrocarbon resin), Preferably it is 3-15 mass parts, More preferably, it is the range of 5-10 mass parts. When the blending ratio is less than 2 parts by mass, the melt viscosity of the pressure-sensitive adhesive composition becomes too high, causing a problem in applicability, and when it exceeds 20 parts by mass, the melt viscosity becomes too low. The flow resistance of the product is inferior, which is not preferable.

In order to impart optical concealability to the composition for a sealing material of the present invention, an inorganic pigment is further dispersed in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass in total of the components (a) to (c). Can be used.
As the inorganic pigment, known pigments used in this field can be used. For example, titanium dioxide (any of anatase type and rutile type), titanium dioxide-coated mica, zinc oxide, molybdenum white, lithopone, barite, calcium carbonate, lead white, talc and other inorganic white pigments; iron oxide (Bengara), Inorganic red pigments such as molybdenum red, iron titanate, silver vermilion, cadmium red, and antimony red; inorganic brown pigments such as γ-iron oxide; yellow iron oxide, ocher, titanium yellow, cadmium yellow, strontium yellow, zinc chromate, etc. Inorganic yellow pigments; inorganic black pigments such as black iron oxide, carbon black, low-order titanium oxide, titanium black; inorganic purple pigments such as mango violet and cobalt violet; emerald green, chromium oxide, chromium hydroxide, titanic acid Inorganic green pigments such as cobalt; ultramarine, bitumen, etc. Machine blue pigments: titanium oxide coated bismuth oxychloride, titanium oxide coated talc, colored titanium oxide coated mica, bismuth oxychloride, pearl pigments such as fish scale foil; metal powder pigments such as aluminum powder and copper powder, etc. Includes one or a mixture of two or more.

  The inorganic pigment preferably has a specific gravity of 6 or less from the viewpoint of uniform dispersibility in the dispersion medium and prevention of sedimentation. In particular, those having an average particle diameter of 1 μm or less and a specific gravity of 5 or less are preferred. Among inorganic pigments, titanium dioxide is particularly preferable because it satisfies these conditions and has high hiding power.

  The blending amount of the inorganic pigment is preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the dispersion medium. If the amount is less than 0.1 parts by mass, sufficient concealability cannot be imparted, and if it exceeds 10 parts by mass, the coating property is lowered, which is not preferable.

  The composition for a sealing material of the present invention is produced by mixing the above polybutene, polyethylene and hydrocarbon resin, or mixing and dispersing an inorganic pigment in these. There is no restriction | limiting in these mixing methods and the apparatus used for mixing, It can select arbitrarily from a well-known method. In addition, at the time of production, pigment dispersion aids, thixotropic agents, wetting agents, organic colorants, organic pigments, viscosity modifiers, preservatives, antioxidants, thermal deterioration inhibitors, etc. May be added.

  As a method of dispersing the inorganic pigment in the dispersion medium, the inorganic pigment may be directly added to the dispersion medium and dispersed. However, in the production process, the polybutene and / or the polyethylene is used as a dispersion medium to contain the inorganic pigment. A method using a master batch is also preferably used. The master batch method contributes to the improvement of work efficiency and uniformity when the inorganic pigment is uniformly dispersed in the dispersion medium.

  The mixing conditions for mixing polybutene, polyethylene and hydrocarbon resin, or further dispersing the inorganic pigment are 120 to 200 ° C., preferably 140 to 170 ° C., usually by stirring for 3 to 17 hours. The mixed sealant composition is then cooled to room temperature.

The excellent effect of the composition for a sealing material of the present invention is a particularly important factor for the cooling conditions to exert the effect of the present invention in addition to the specific requirements of each constituent material according to the present invention described above.
The cooling rate needs to be 1 ° C./min or more, preferably 3 ° C./min or more, more preferably 5 ° C./min or more. By setting the cooling rate to 1 ° C./min or more, the flow resistance of the pressure-sensitive adhesive is greatly improved. The reason for this is not clear, but by increasing the cooling rate, the branching of the high-pressure polyethylene is greatly expanded. Apparently, polyethylene occupies a large space volume, resulting in improved bleed resistance. Inferred.
On the other hand, if the cooling is performed slowly at a cooling rate of less than 1 ° C./min, the effect of suppressing bleeding by the high-pressure polyethylene is lost. The reason for this is that when the cooling rate is low, the branching of the polyethylene becomes a small and widened state. Apparently, the polyethylene exists in a small space volume, and the expression of the intermolecular interaction becomes poor.

  The cooling method is not particularly limited as long as a cooling rate of 1 ° C./min or more can be maintained. Preferably, if melt-kneading is performed in a mixing tank having a jacket, a known mechanical method such as a cooling method for circulating a refrigerant instead of the heat medium that has been circulated in the jacket during the melt-kneading. The method can be used.

  The composition for a sealing material of the present invention is characterized in that the oil separation degree is 0.1% or less when one week elapses in a thermostatic bath maintained at 60 ° C. according to JIS-K-2220. By setting the temperature at 60 ° C., it becomes an accelerating condition and a bleed-out is more likely to occur. That is, the composition for a sealing material of the present invention has very good compatibility between polybutene and polyethylene, and the polybutene does not bleed out and is excellent in molding processability.

  The composition for a sealing material of the present invention is not limited to general application by, for example, rolls or brushes, but can use a method for forming various coating films such as spread application by immersion, application by filling or injection, and the like. . That is, since the composition for a sealing material of the present invention has sufficient fluidity under an appropriate shear stress, it can be used by any method such as dipping, brushing or pouring in addition to coating. . By applying and spreading these on the surface of various materials, their excellent concealability, sealing properties, and heat resistance enhance design and discrimination, for example, applications such as markers and sealing materials such as dry cells Etc. can be used.

  Hereinafter, the contents of the present invention will be specifically described by comparing Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, each component used is as follows.

(1) Polybutene A raw material was obtained by diluting the remaining raffinate fraction obtained by extracting butadiene from a C4 fraction obtained from an ethylene production apparatus by naphtha decomposition with isobutane. The raw material composition analyzed by gas chromatography is shown in Table 1. This was passed through alumina for dehydration and impurity removal treatment. This raw material was supplied to an autoclave having an internal volume of 500 ml at 280 g per hour. To this feedstock, aluminum chloride dispersed in an isobutene oligomer (mixture of 2 to 5 mer) is supplied so as to be 0.1% by mass with respect to butylenes. Polymerization was carried out continuously at the reaction temperature. The polymerization solution was purified by distillation after removing the catalyst. Table 2 shows the reaction temperature and molecular weight of the polybutenes A to C used.

(2) Polyethylene Polyethylene: LJ-600 (manufactured by Nippon Polyethylene Co., Ltd.), MFR = 5.5, density = 0.920 g / cm ³

(3) Hydrocarbon resin Hydrocarbon resin A; Escorez 5300 manufactured by Exxon Mobil Chemical Co., softening point 105 ° C
Hydrocarbon resin B: Escorez 1304 manufactured by Exxon Mobil Chemical, softening point 100 ° C.

(4) Inorganic pigment Titanium dioxide: KA-10 (anatase type) (manufactured by Titanium Industry Co., Ltd.), specific gravity 3.9, average particle size = 0.3 to 0.6 μm
(5) Antioxidant Polymer phenolic antioxidant: Irganox 1010 (manufactured by BASF Corporation)

(Examples 1-5, Comparative Examples 1-2)
[Manufacture of composition for sealing material]
A predetermined amount of each of the components shown in Table 1 was taken in a 500 cc beaker, heated to 140 ° C. with stirring, and stirring was maintained at 630 rpm at the same temperature. Next, a predetermined amount of an antioxidant and, if necessary, an inorganic pigment was added, and stirring was continued until the contents of the beaker became uniform, thereby obtaining a composition for a sealing material.

[Evaluation test of composition for sealing material]
[A] Appearance In order to examine whether polyethylene, polybutene and hydrocarbon resin are completely compatible and stable, the following operation is performed.
(1) About 400 g of a sample heated to about 160 ° C. is collected in a 500 ml glass beaker.
(2) After cooling to room temperature, the sample was visually observed for the presence of color and foreign matter.
[B] Melt viscosity In order to evaluate the coating performance of the composition for sealing materials, the melt viscosity at 160 ° C is measured in accordance with JIS-K-7117.
[C] Oil separation degree test The oil separation degree is measured when one week elapses in a constant temperature bath maintained at 60 ° C in accordance with JIS-K-2220.

[Evaluation results of composition for sealing material]
The evaluation results are shown in Table 3.
As is apparent from Table 3, in the composition for sealing material of the present invention, polyethylene and polybutene are well compatible with each other by the addition of a hydrocarbon resin, the oil separation test at 60 ° C. is good, and the bleed of polybutene is also good. Not observed. On the other hand, in the case where the hydrocarbon resin was not added, bleeding occurred in the oil separation test at 60 ° C., and there was a problem in use (Comparative Example 1). Moreover, the composition (Comparative Example 2) using polybutene having a number average molecular weight smaller than that of the component (b) has a melt viscosity that is too low, and the coating composition may flow out during the coating operation.
In addition, although each composition was manufactured with the said manufacturing method, stirring was stopped in the state of 140 degreeC after completion of manufacture, and the situation of the pigment sedimentation for 10 minutes was observed, but about the composition of any Example, pigment sedimentation was carried out. There was no problem with respect to the stable dispersion of the pigment.

  The composition for a sealing material of the present invention has excellent sealing performance at an application site, and also suppresses bleed out of polybutene from the application site even during long-term use, and forms a seal with excellent sealing performance, which is extremely useful industrially. It is.

Claims (5)

(A) 2 to 20 parts by mass of polyethylene having a density of 0.916 to 0.930 g / cm ³ and MFR4 or more, (b) 98 to 80 parts by mass of polybutene having a number average molecular weight of 700 to 2500 , and (c) hydrocarbon. 2-20 parts by mass of the resin ((a), (b) and (a total of 100 parts by weight of c)) were mixed with Tona Ru composition at 120 to 200 [° C., the cooling rate of more than 1 ° C. / min The composition for sealing materials obtained by cooling at 60 ° C. and having a degree of oil separation at 60 ° C. of 0.1% or less in one week.   The composition for a sealing material according to claim 1, wherein the (c) hydrocarbon resin is an alicyclic hydrocarbon resin and / or an aliphatic hydrocarbon resin. The composition for sealing materials according to claim 1 or 2, wherein 100 parts by mass of the composition for sealing materials is used as a dispersion medium, and 0.1 to 10 parts by mass of an inorganic pigment is dispersed. (A) 2 to 20 parts by mass of polyethylene having a density of 0.916 to 0.930 g / cm ³ and MFR4 or more, (b) 98 to 80 parts by mass of polybutene having a number average molecular weight of 700 to 2500 , and (c) hydrocarbon. After mixing a composition consisting of 2 to 20 parts by mass of resin (the total of (a), (b) and (c) is 100 parts by mass) at 120 to 200 ° C., at a cooling rate of 1 ° C./min or more. A method for producing a composition for a sealing material, wherein the oil separation degree at 60 ° C. is 0.1% or less per week, characterized by cooling. The method for producing a composition for a sealing material according to claim 4, wherein the (c) hydrocarbon resin is an alicyclic hydrocarbon resin and / or an aliphatic hydrocarbon resin.