Sealant and automotive sealant

Abstract

To improve the absorption rate of a plasticizer into the voids between the molecular chains of polyvinyl chloride and to lower the absorption start temperature of the plasticizer into the voids between the molecular chains of polyvinyl chloride.SOLUTION: The present invention provides a sealant containing a plastisol composition, wherein the plastisol composition contains a resin composition and a plasticizer A, wherein the resin composition is a polymer alloy containing polyvinyl chloride, a modifying resin, and a plasticizer B, and wherein the plasticizer B is the same type of plasticizer as the plasticizer A, or a different type of plasticizer from the plasticizer A.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a sealing material and a sealing material for automobiles.

Background Art

[0002] Conventionally, a sealing material for automobiles is a paste-like material (a plastisol composition) composed of inexpensive polyvinyl chloride (PVC) and an oily plasticizer. The material is heated to a high temperature in a drying furnace to expand the distance between the molecular chains of PVC, thereby solubilizing PVC and the plasticizer. However, from the perspective of environmental protection, there is a demand for the development of a sealing material that can reduce the amount of carbon dioxide emissions by lowering the temperature of the drying furnace (lowering the temperature at which the sealing material gels) and reducing the energy consumption.

[0003] As a sealing material that gels at a low temperature, a plastisol composition produced by adding a plasticizer to an acrylic polymer having a polar group is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since the plastisol composition described in Patent Document 1 has a special multilayer structure, there are problems in lowering the temperature of the drying process and suppressing the absorption of the plasticizer during storage.

[0006] The present application aims to improve the absorption rate of the plasticizer into the voids between the molecular chains of polyvinyl chloride and lower the absorption start temperature of the plasticizer into the voids between the molecular chains of polyvinyl chloride in order to solve the above problems.

Means for Solving the Problems

[0007] [1] A sealing material containing a plastisol composition, The plastisol composition contains a resin composition and a plasticizer A, The resin composition is a polymer alloy containing polyvinyl chloride, a modified resin, and a plasticizer B, The plasticizer B is the same type of plasticizer as the plasticizer A or a different type of plasticizer from the plasticizer A, a sealing material.

[0008] According to the sealing material of the present invention, by compatibilizing polyvinyl chloride with a modified resin and a plasticizer B to form a resin composition, the intermolecular interaction of polyvinyl chloride is weakened, and the distance between the molecular chains of polyvinyl chloride is expanded. As a result, the plasticizer is more easily absorbed between the molecular chains of polyvinyl chloride even at a low temperature. Further, by blending a modified resin having a low active start temperature of molecular motion, the absorption rate of the plasticizer into the voids between the molecular chains of polyvinyl chloride can be improved, and the absorption start temperature of the plasticizer can be lowered. Furthermore, since the above resin composition already has a plasticizer absorbed between the molecular chains of polyvinyl chloride, there is already a plasticizer between the molecules of polyvinyl chloride, and the plasticizer absorption reaction is in a chemical equilibrium state, the swelling reaction with the plasticizer is not promoted at room temperature, and it does not gel even after long-term storage, so it has excellent storage stability when used industrially.

[0009] [2] The modified resin is a resin having a polyolefin backbone, the sealing material according to [1].

[0010] When the sealing material of the present invention compatibilizes polyvinyl chloride with a resin having a polyolefin backbone as a modified resin, the intermolecular interaction of polyvinyl chloride is weakened, so that the absorption temperature of the plasticizer can be appropriately adjusted in a wide range of 60°C to 120°C, and the heating time can be shortened (5 minutes to 10 minutes).

[0011] [3] The content of the modified resin with respect to a total of 100 parts by mass of the polyvinyl chloride and the modified resin is 5 parts by mass or more and 80 parts by mass or less, the sealing material according to [1] or [2].

[0012] The sealing material of the present invention changes the intermolecular interaction of polyvinyl chloride by setting the content of the modified resin to 5 parts by mass to 80 parts by mass with respect to a total of 100 parts by mass of polyvinyl chloride and the modified resin, and can appropriately adjust the absorption temperature of the plasticizer with respect to polyvinyl chloride.

[0013] [4] An automotive sealing material comprising the sealing material according to any one of [1] to [3].

[0014] Since the automotive sealing material of the present invention contains a plastisol composition obtained by heating a plasticizer in a wide range of 60°C to 120°C, for example, when gelling a sealing agent used at a joint of an automotive steel plate, the heating temperature can be lowered and the heating time can be shortened. Therefore, it is possible to reduce the carbon dioxide discharged when forming a coating film made of the sealing material and suppress the energy used.

Effects of the Invention

[0015] According to the present invention, it is possible to improve the absorption rate of the plasticizer with respect to the voids between the molecular chains of polyvinyl chloride and lower the absorption start temperature of the plasticizer with respect to the voids between the molecular chains of polyvinyl chloride.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail.

[0017] [Sealing Material] The sealing material according to an embodiment of the present invention is a sealing material containing a plastisol composition. In the sealing material of the present embodiment, the plastisol composition contains a resin composition and a plasticizer A. The resin composition is a polymer alloy containing polyvinyl chloride, a modified resin, and a plasticizer B. The plasticizer B is a plasticizer of the same type as the plasticizer A or a plasticizer of a different type from the plasticizer A.

[0018] "Plastisol composition" Examples of plasticizer A include phthalate plasticizers such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, etc.; adipate plasticizers such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, dihexyl adipate, di-2-ethylhexyl adipate, diisononyl adipate, dibutyl diglycol adipate, etc.; phosphate plasticizers such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl phenyl phosphate, etc.; trimellitate plasticizers such as tri-2-ethylhexyl trimellitate, etc.; sebacate plasticizers such as dimethyl sebacate, dibutyl sebacate, di-2-ethylhexyl sebacate, etc.; aliphatic polyester plasticizers such as poly-1,3-butanediol adipate, etc.; benzoate plasticizers such as diethylene glycol dibenzoate, dibutylene glycol dibenzoate, etc.; epoxidized ester plasticizers such as epoxidized soybean oil, etc.; phenyl alkyl sulfonate plasticizers such as phenyl alkyl sulfonate, etc.; alicyclic dibasic acid ester plasticizers; polyether plasticizers such as polypropylene glycol, polybutylene glycol, etc.; and citrate plasticizers such as acetyl tributyl citrate, etc. These may be used alone or in combination of two or more. Among these, from the viewpoints of price and availability, it is preferable to use one or more of dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, phenyl alkyl sulfate, and acetyl tributyl citrate as the main component.

[0019] The content of plasticizer A relative to the total mass (100% by mass) of the plastisol composition is preferably 5% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less. When the content of plasticizer A is at least the above lower limit value, the gelation of the resin proceeds sufficiently, and the mechanical elongation of the plastigel composition after the plasticizer is absorbed can be improved. When the content of plasticizer A is at most the above upper limit value, the plasticizer absorption amount of the resin does not become excessive, so that sufficient mechanical strength can be ensured.

[0020] In addition to the resin composition and plasticizer A, the plastisol composition may contain, as required, a filler, an adhesive, a pigment, a diluent, an antifoaming agent, a fungicide, a leveling agent, etc.

[0021] Examples of the filler include calcium carbonate, aluminum hydroxide, colloidal silica, talc, glass powder, aluminum oxide, etc. The content of the filler in the plastisol composition can be appropriately selected according to the purpose.

[0022] The adhesive can be appropriately selected according to the type of the base material to which the sealing material is applied. Examples of the adhesive include adhesives such as epoxy resins, block urethane resins, and polyamines. These may be used alone or in combination of two or more. Furthermore, a curing agent for the adhesive can also be used. For example, for an epoxy resin, curing agents such as acid anhydrides and imidazole compounds can be used, and for a block urethane resin, curing agents such as dihydrazide compounds can be used.

[0023] Examples of the pigment include titanium oxide, carbon black, etc. Examples of the diluent include mineral turpentine, mineral spirit, etc.

[0024] The content of the resin composition relative to the total mass (100% by mass) of the plastisol composition is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and still more preferably 15% by mass or more and 30% by mass or less. When the content of the resin composition is at least the lower limit value, the mechanical elongation rate of the plastisol composition itself can be ensured due to the contribution of the resin component. When the content of the resin composition is at most the upper limit value, the mechanical strength of the material can be improved by blending additives such as fillers, and the cost can be suppressed.

[0025] The plastisol composition can be produced, for example, by dispersing the resin composition in a plasticizer. To disperse the resin composition in the plasticizer, a known mixer can be used. Examples of the mixer include a Pony mixer, a Change-can mixer, a Hobert mixer, a planetary mixer, a butterfly mixer, a raikai machine, a kneader, and the like.

[0026] "Resin composition" As the polyvinyl chloride, a polyvinyl chloride homopolymer is used.

[0027] The content of polyvinyl chloride relative to the total mass (100% by mass) of the resin composition is preferably 20% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 60% by mass or less, and still more preferably 40% by mass or more and 50% by mass or less. When the content of polyvinyl chloride is at least the lower limit value, flame retardancy and mechanical strength can be ensured, and since polyvinyl chloride is inexpensive, the manufacturing cost of the plastisol composition can be suppressed. When the content of polyvinyl chloride is at most the upper limit value, the ratio of the modified resin can be increased, so that the absorption start temperature of the plasticizer can be lowered to a lower temperature.

[0028] Examples of the modified resin include resins having a polyolefin backbone, resins having a solubility parameter close to that of polyvinyl chloride, and the like. Among these, resins having a polyolefin backbone are preferred.

[0029] Examples of the resin having a polyolefin skeleton include ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), chlorinated polyethylene (CPE), thermoplastic polyamide (PA), acid-modified polyethylene, thermoplastic elastomer (TPO), and the like. These resins are modified resins with a low active start temperature of molecular motion.

[0030] The content of the modified resin with respect to the total mass (100% by mass) of the resin composition is preferably 10% by mass or more and 40% by mass or less, more preferably 15% by mass or more and 30% by mass or less, and still more preferably 20% by mass or more and 25% by mass or less. When the content of the modified resin is at least the lower limit value, the absorption start temperature of the plasticizer can be further lowered. When the content of the modified resin is at most the upper limit value, the flame retardancy and mechanical strength derived from the properties of polyvinyl chloride can be ensured, and since polyvinyl chloride is inexpensive, the cost of the plastisol composition can be reduced.

[0031] The content of the modified resin with respect to 100 parts by mass in total of polyvinyl chloride and the modified resin is preferably 5 parts by mass or more and 80 parts by mass or less, more preferably 10 parts by mass or more and 50 parts by mass or less, and still more preferably 20 parts by mass or more and 40 parts by mass or less. When the content of the modified resin with respect to 100 parts by mass in total of polyvinyl chloride and the modified resin is at least the lower limit value, the active start of molecular motion by the modified resin becomes remarkable, so that the absorption start temperature of the plasticizer can be further lowered. When the content of the modified resin with respect to 100 parts by mass in total of polyvinyl chloride and the modified resin is at most the upper limit value, the flame retardancy and mechanical strength derived from the properties of polyvinyl chloride can be ensured, and since polyvinyl chloride is inexpensive, the cost of the plastisol composition can be reduced.

[0032] As the plasticizer B, the same ones as the plasticizer A are used. Plasticizer B may be the same type of plasticizer as plasticizer A or a different type of plasticizer from plasticizer A. When plasticizer B is a different type of plasticizer from plasticizer A, examples of the combination of plasticizer A and plasticizer B include a combination where plasticizer A is diisononyl phthalate and plasticizer B is trinormalalkyl trimellitate, a combination where plasticizer A is diisononyl phthalate and plasticizer B is bis(2-ethylhexyl) phthalate, a combination where plasticizer A is diisononyl phthalate and plasticizer B is bis(2-ethylhexyl) 4-cyclohexene-1,2-dicarboxylate, etc. are preferable.

[0033] The content of plasticizer B with respect to the total mass (100% by mass) of the resin composition is preferably 5% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 50% by mass or less, and even more preferably 20% by mass or more and 40% by mass or less. When the content of plasticizer B is at least the above lower limit value, powdered polyvinyl chloride aggregates, enabling molding in the mixing step and granulation step. When the content of plasticizer B is at most the above upper limit value, the plasticizer absorption amount of the resin composition is not saturated (room is left in the absorption amount), so that the plasticizer can be sufficiently absorbed in subsequent steps.

[0034] The ratio of plasticizer B to plasticizer A (plasticizer B / plasticizer A) is preferably 0.05 or more and 0.5 or less, more preferably 0.1 or more and 0.4 or less, and even more preferably 0.2 or more and 0.3 or less in terms of mass ratio. When the above ratio is at least the above lower limit value, the storage stability can be improved because the plasticizer is sufficiently contained between the molecular chains of the resin component. When the above ratio is at most the above upper limit value, the plasticizer absorption amount of the resin composition is not saturated (room is left in the absorption amount), so that the plasticizer can be sufficiently absorbed in subsequent steps.

[0035] According to the sealing material of the present embodiment, it is possible to improve the absorption rate of the plasticizer with respect to the voids between the molecular chains of polyvinyl chloride and lower the absorption start temperature of the plasticizer with respect to the voids between the molecular chains of polyvinyl chloride.

[0036] [Manufacturing method of sealing material] The manufacturing method of the sealing material of the present embodiment includes a step of preparing a resin composition containing polyvinyl chloride, a modified resin, and plasticizer B (hereinafter referred to as "the first step"), and a step of preparing a plastisol composition containing the resin composition and plasticizer A (hereinafter referred to as "the second step").

[0037] In the first step, polyvinyl chloride, a modified resin, and plasticizer B are blended at a predetermined ratio, kneaded, and then granulated (pulverized) to produce a polymer alloy (resin composition) containing polyvinyl chloride, a modified resin, and plasticizer B.

[0038] As the kneading method, for example, a twin-screw extrusion kneader, a single-screw extrusion kneader, a Banbury mixer, a pressure kneader, etc. are used. As the granulation method, a powder mill (fine pulverizer), an impact pulverizer, a stamp pulverizer, etc. are used.

[0039] The temperature during kneading is preferably 60°C or higher and 160°C or lower, more preferably 100°C or higher and 150°C or lower. When the temperature is at least the lower limit value, the fluidity of the resin increases, and each material can be uniformly dispersed. When the temperature is at most the upper limit value, by suppressing the thermal decomposition of polyvinyl chloride, it is possible to mold without impairing the characteristics of the resin composition. The temperature during granulation is preferably 0°C or higher and 100°C or lower, more preferably 10°C or higher and 60°C or lower. When the temperature is at least the lower limit value, the impact resistance of the resin composition can be ensured, and a uniform particle size can be easily obtained. When the temperature is at most the upper limit value, since the softening of the resin composition is suppressed and the residue on the equipment is suppressed, the productivity can be improved.

[0040] The kneading time is preferably 3 minutes or more and 15 minutes or less, more preferably 5 minutes or more and 10 minutes or less. When the time is at least the lower limit value, a sufficient stirring time can be obtained, and each material can be uniformly dispersed. When the time is at most the upper limit value, excessive heating of the material can be prevented, and the thermal decomposition of polyvinyl chloride can be suppressed. The granulation (grinding) time is preferably 20 minutes or more and 180 minutes or less, more preferably 60 minutes or more and 120 minutes or less. When the time is at least the lower limit value, a sufficient granulation (grinding) time can be obtained and a uniform particle size can be obtained. When the time is at most the upper limit value, heat generation of the material due to shear can be prevented, so that the residue on the equipment is suppressed and the productivity can be improved.

[0041] In the second step, a plasticizer A and various additives are blended with the resin composition obtained in the first step at a predetermined ratio, and these are stirred to prepare a plastisol composition.

[0042] As the stirring method, for example, a planetary mixer, a pony mixer, a twin-screw mixer, a butterfly mixer, etc. are used.

[0043] The temperature during stirring is preferably 0°C or more and 40°C or less, more preferably 10°C or more and 30°C or less. When the temperature is at least the lower limit value, the viscosity during stirring decreases, enabling stable stirring. When the temperature is at most the upper limit value, absorption of plasticizer A by the resin composition during stirring can be suppressed.

[0044] The stirring time is preferably 5 minutes or more and 180 minutes or less, more preferably 60 minutes or more and 120 minutes or less. When the time is at least the lower limit value, the resin composition and the plasticizer are sufficiently stirred, so that the materials can be uniformly dispersed. When the time is at most the upper limit value, accumulation of shear heat generated during stirring can be suppressed, so that absorption of plasticizer A by the resin composition can be suppressed.

[0045] Through the above steps, the sealing material of this embodiment is obtained.

[0046] The manufacturing method of the sealing material of the present embodiment is such that, in the first step, by compatibilizing a modified resin and plasticizer B with polyvinyl chloride to form a resin composition, the intermolecular interaction of polyvinyl chloride can be weakened and the distance between the molecular chains of polyvinyl chloride can be expanded. As a result, even at a low temperature, the plasticizer is easily absorbed between the molecular chains of polyvinyl chloride. Further, by blending a modified resin having a low active start temperature of molecular motion, the absorption rate of the plasticizer into the voids between the molecular chains of polyvinyl chloride can be improved and the absorption start temperature of the plasticizer can be lowered. Note that at the end of the first step, in the resin composition (polymer alloy), plasticizer B has already been absorbed between the molecular chains of polyvinyl chloride and plasticizer already exists between the molecules of polyvinyl chloride, and since the plasticizer absorption reaction is in a chemical equilibrium state, the swelling reaction with the plasticizer is not promoted at room temperature. Therefore, the obtained sealing material is less likely to gel even after long-term storage and thus has excellent storage stability when used industrially.

[0047] The manufacturing method of the sealing material of the present embodiment is such that, in the second step, by blending plasticizer A into the resin composition, the swelling reaction between polyvinyl chloride and plasticizer A is promoted, so that it becomes possible to gel the sealing material at a lower temperature than before.

[0048] [Automobile sealing material] The automobile sealing material according to one embodiment of the present invention is composed of the sealing material of the above-described embodiment.

[0049] According to the automobile sealing material of the present embodiment, the heating temperature when gelling the sealing material used for the joint of the automobile steel plate can be lowered and the heating time can be shortened. Therefore, it is possible to reduce the carbon dioxide emitted when forming the coating film made of the sealing material and suppress the energy used.

Industrial applicability

[0050] The sealing material of the present invention does not promote the swelling reaction with the plasticizer at room temperature, and the plasticizer is hardly absorbed even after long-term storage, so it has excellent storage stability when used industrially. Therefore, it has industrial applicability.

Claims

1. A sealant comprising a plastisol composition, The plastisol composition contains a resin composition and a plasticizer A, The resin composition is a polymer alloy containing polyvinyl chloride, a modified resin, and a plasticizer B, The sealing material, wherein the plasticizer B is the same type of plasticizer as the plasticizer A or a different type of plasticizer from the plasticizer A.

2. The sealant according to claim 1 , wherein the modified resin is a resin having a polyolefin skeleton.

3. The sealing material according to claim 1 , wherein the content of the modifying resin is 5 parts by mass or more and 80 parts by mass or less relative to a total of 100 parts by mass of the polyvinyl chloride and the modifying resin.

4. A sealing material for automobiles, comprising the sealing material according to any one of claims 1 to 3.