JP4251414B2 - Undercoat agent for noise prevention - Google Patents

Description

【００５３】
【表２】

＊１ コポリマーレジン（塩化ビニル−酢酸ビニルコポリマー，
酢酸ビニル含有量８重量％，平均重合度１９００，
平均粒径１μｍ以下）
＊２ ジプロピレングリコールベンゾエート
＊３ アジピン酸ポリエステル，分子量２０００
＊４ パラフィン系炭化水素，沸点１７０℃
【００５４】
表１，２の結果より、可塑剤としてＤＩＮＰや安息香酸エステル系可塑剤にＴＯＴＭやポリエステル可塑剤を併用し、ポリアミドアミンとブロックイソシアネートを用いることで、ブラックアウト適性が向上し、しかも工程感放置のふくれもなく、また耐水性、耐腐食性が良好で騒音防止効果に優れた塗膜が形成されることが認められた。
【００５５】
【発明の効果】
本発明によれば、形成された塗膜上にブラックアウト塗料が塗布されても，これによってべたつきがなく、かつ塗膜塗布後に高湿度に放置し、焼付けを行ってもふくれが生じることがなく、しかも耐チッピング性、耐水性、耐腐食性の良好な騒音防止効果に優れた塗膜を形成できる。
【図面の簡単な説明】
【図１】石ハネ音低減効果測定装置の側面図である。
【図２】石ハネ音低減効果測定装置の正面図である。
【符号の説明】
１ 枠
２ 塗膜
３ パイプ
４ マイクロホン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a noise-preventing undercoat agent that is suitable as an undercoat for a portion where noise due to a stone splash such as an under floor portion of an automobile or a panel of a wheel house portion should be prevented.
[0002]
[Prior art and problems to be solved by the invention]
Stones and sand are often generated in the under floor and wheel house (tire house) of automobiles during driving, generating noise that is unpleasant to the driver.
[0003]
Conventionally, as a method for preventing such stone and sand splashes, a non-foamed vinyl chloride resin (PVC) paint or an unexpanded balloon is applied to the floor of an automobile or a panel of a wheel house. A low-foaming type vinyl chloride resin (PVC) paint having a foaming ratio of around 50% is used as an undercoat agent.
[0004]
However, when the former non-foamed PVC is used, if the coating layer becomes thicker, there is an effect of reducing stone and sand splash noise, but the cost increases and the work efficiency decreases due to an increase in the coating amount. The vehicle weight increases due to the increase in weight.
[0005]
On the other hand, when the low foam type PVC paint using the latter unexpanded balloon is used, the soundproofing effect is improved by the effect of increasing the thickness of the coating layer compared with the non-foam type PVC paint, but the unexpanded balloon is used. Since the foam becomes a harder film than the foam made of the foaming agent, the impact absorbing effect at the time of stone and sand impact is reduced, and the soundproofing effect is inferior. Further, the cushioning property is lowered by the balloon membrane, and the chipping resistance is extremely lowered. In this case, for extremely lowering chipping resistance, a compound that improves the physical properties of the compound (for example, low filling of unexpanded balloon, increasing the ratio of vinyl chloride-vinyl acetate copolymer) can be used. A certain level value is secured, but it is not enough.
[0006]
In addition, since heat resistance of 130 to 160 ° C. is required for use in an automobile production line, the material of the unexpanded balloon is acrylonitrile polymer alone or acrylonitrile of acrylonitrile-vinylidene chloride copolymer having good heat resistance. A high ratio is used. However, vinylidene chloride is inferior in heat resistance, and when the acrylonitrile ratio increases, the content of acrylonitrile monomer increases, which is not desirable from the viewpoint of environmental hygiene.
[0007]
From this point of view, a foam type PVC paint using an organic foaming agent is desired. However, when this type of foamed PVC paint using an organic foaming agent is applied to a floor of a car, a panel of a wheel house, or the like. The coating film is excellent in water resistance and corrosion resistance, and it does not change the painting process of automobiles. In this case, after applying the paint at the end of work, leave it overnight without baking. Therefore, it is desired that no blistering occurs even if baking is performed after such standing.
[0008]
Furthermore, after the undercoat agent is baked, a paint called blackout (normally dry solvent-type paint) is applied on the undercoat film before the tire is finally attached. Therefore, there is a need for a solution to this problem.
[0009]
Accordingly, an object of the present invention is to provide an undercoat agent for noise prevention that satisfies such requirements.
[0010]
Means for Solving the Problem and Embodiment of the Invention
As a result of intensive studies to achieve the above object, the present inventor has found that an undercoat agent containing a vinyl chloride resin, an organic foaming agent, a filler, and a plasticizer is a phthalate ester or benzoate ester plastic. A comparatively small amount of trimellitic acid ester or polyester plasticizer is used in combination with an adhesive, and block isocyanate and polyamidoamine are blended as adhesive components to provide excellent chipping resistance and excellent blackout suitability. It has been found that, in addition to being excellent in water resistance, there is no blistering even if it is stood overnight after coating, and it has excellent adhesion when left between processes. That is, the stickiness of the blackout paint film is because the blackout paint contains an organic solvent, so the plasticizer in the baked undercoat film is partially extracted by the solvent of the blackout paint, and this is the blackout paint film. In this case, a phthalate plasticizer is usually used as the plasticizer for the undercoat film. In such a plasticizer, the blackout coating film is softened as described above. Although it causes stickiness, when a trimellitic acid ester plasticizer or polyester plasticizer is used in combination as a plasticizer, the blackout coating is not softened and does not cause stickiness. In this case, phthalate plasticizer and benzoate plasticizer By using an ester plasticizer and polyester plasticizer in combination, chipping resistance is improved, excellent noise prevention performance is provided, and as described above, water resistance is also excellent, and there is no swelling during standing between processes. From this, it was found that an undercoat agent excellent in usability can be obtained, and the present invention has been made.
[0011]
Therefore, the present invention relates to a noise-preventing undercoat agent containing a vinyl chloride resin, an organic foaming agent, a filler, and a plasticizer. The plasticizer includes a phthalate ester plasticizer or a benzoate ester plasticizer as 100 weight. A noise-preventing undercoat agent comprising 15 to 30 parts by weight of a trimellitic ester plasticizer or a polyester plasticizer in combination with a part and a block isocyanate and a polyamidoamine as blending components provide.
[0012]
The noise-preventing undercoat agent of the present invention is used to form an undercoat film for places where noise due to stone and sand splashes such as automobile floors and wheel house panels should be prevented. Even a single layer can effectively prevent the noise, and can be incorporated into the current automobile painting process without changing the process. In this case, the blackout coating film has excellent blackout suitability as described above. Softens and does not cause stickiness, and even if there is a time lag between coating and baking, there is no blistering on the undercoat film, and it also has a water-proof and corrosion-resistant noise prevention effect. An excellent undercoat film can be provided.
[0013]
Hereinafter, the present invention will be described in more detail.
The undercoat agent for noise prevention of the present invention uses a vinyl chloride resin as a base polymer, and an organic foaming agent, if necessary, a foaming aid, a filler, a plasticizer, and an adhesive component are further blended. Is a mixture of a hygroscopic agent, a stabilizer, a colorant and the like.
[0014]
Here, the vinyl chloride resin (PVC) is mainly composed of a homopolymer of vinyl chloride, vinyl chloride and a copolymer with other copolymerizable monomers such as vinyl acetate (vinyl chloride content 50% by weight). As mentioned above, in particular, 70% by weight or more) can be used alone or in combination of two or more.
[0015]
In this case, PVC has an average particle size of 5 μm or less, preferably 3 μm or less, and more preferably 1.5 μm or less. Use of a PVC having a large average particle diameter exceeding 5 μm reduces chipping resistance and causes abnormal foaming on the foamed surface, which may be undesirable in terms of appearance. In addition, as the PVC, those having two peaks in the particle size distribution in the above average particle size range are preferably used from the viewpoint of workability and physical properties of the obtained foamed PVC. It is done. The PVC having a particle size distribution having two peaks here is different from a mixture of two types of PVC having different average particle sizes, and a part of the primary particles having a small particle size is in the manufacturing process. The secondary particles are obtained by agglomeration in the above, and the primary particles having a small particle diameter and the secondary particles obtained by agglomerating the secondary particles coexist, thereby having two peaks in the particle size distribution.
[0016]
Further, as the PVC, an average degree of polymerization of 2500 or less, preferably 2000 or less, more preferably 1900 or less is desirable. When the average degree of polymerization is too high, physical properties of the foamed PVC such as chipping resistance may be deteriorated. The lower limit of the average degree of polymerization is usually 500, preferably 850, and more preferably 1000.
[0017]
As the copolymer, vinyl chloride-vinyl acetate copolymer is preferably used from the viewpoint of swelling gelation. In this vinyl chloride-vinyl acetate copolymer, the vinyl acetate content is 1 to 15% by weight, particularly 3 to 10%. A weight percent is preferred. In this case, the vinyl chloride homopolymer is somewhat inferior in adhesion to the metal surface compared to the vinyl chloride-vinyl acetate copolymer, while the vinyl chloride-vinyl acetate copolymer has a good swelling gelling property for the plasticizer and adheres when heated. Although it is good, the cost is high, so it is preferable to use both in combination. The ratio of the combined use is appropriately selected, but it is preferable that the vinyl chloride homopolymer: vinyl chloride-vinyl acetate copolymer = 4: 1 to 1: 4 (weight ratio).
[0018]
Further, as a copolymer, -CH₂Crosslinkable copolymers having ROH groups can also be used. This OH group reacts with blocked isocyanate as an adhesion component, which will be described later, upon heating to produce a urethane bond, thereby improving adhesion and water resistance.
[0019]
Next, in the present invention, as the organic foaming agent used for foaming PVC, it is preferable to use a foaming agent having a decomposition temperature of 130 to 180 ° C., a foaming agent mixture, or a mixture of a foaming agent and a foaming aid. Those having a decomposition temperature exceeding 180 ° C. do not foam well at a temperature of 120 to 160 ° C., while those having a decomposition temperature lower than 130 ° C. are out of gas before the PVC is cured, and the expansion ratio is 1. In some cases, the foamed PVC of 2 to 1.6 times cannot be obtained and the storage stability is inferior.
[0020]
Specifically, 4,4′-oxybis (benzenesulfonyl hydrazide (OBSH) can be suitably used as the foaming agent, and p-toluenesulfonyl azide, p-methylurethanebenzenesulfonyl hydrazide, and the like can be used. Moreover, as a foaming agent mixture, a mixture of OBSH and azodicarbonamide (ADCA), etc. can be mentioned as a suitable thing. Furthermore, like ADCA alone, the decomposition temperature exceeds 180 ° C., but foaming When used in combination with an auxiliary agent, those having a decomposition temperature adjusted to 130 to 180 ° C. can also be suitably used, and foaming agents and foaming agent mixtures having a decomposition temperature in the range of 130 to 180 ° C., such as OBSH. Even if foaming aids are used in combination, there is no problem as long as the decomposition temperature is 130 to 180 ° C.
[0021]
Known foaming aids can be used, and various metal oxides (for example, zinc oxide and magnesium oxide), metal soaps (for example, zinc stearate), urea compounds, amines and the like can be mentioned. In addition, such a foaming auxiliary agent can be blended for other purposes at the same time. For example, metal soap is used as a surface treatment agent for inorganic fillers such as calcium carbonate, and the metal soap used as such a surface treatment agent is used here as long as the decomposition temperature of the foaming agent is lowered. Included in the agent.
[0022]
The blending amount of the organic foaming agent is usually 1 to 3 parts with respect to 100 parts by weight of PVC (parts by weight, hereinafter the same), preferably 1 to 3 parts of foaming agent or foaming agent mixture, particularly 1.5 to 2. 5 parts, foaming aid 0-15 parts, especially 1-10 parts.
[0023]
In the present invention, examples of the filler include calcium carbonate, barium sulfate, clay, diatomaceous earth, silica, talc, and the like, and these can be used alone or in combination of two or more. If necessary, hollow particles such as glass balloons and resin balloons can be blended.
[0024]
In this case, it is particularly preferable to use a surface-treated inorganic filler such as surface-treated calcium carbonate. The average particle diameter of the inorganic filler is 0.01 to 1 μm, particularly 0.02 to 0.1 μm, and BET Specific surface area by the method is 5-30m²/ G, especially 15-25m²/ G is preferred. By using a fine particle surface treatment filler and not adding a coarse filler, uniform dispersion into the PVC paste can be achieved and the foamed cells can be made dense. In addition, by using a surface-treated inorganic filler with a high specific surface area, a large amount of plasticizer can be added without hindrance, and by increasing the amount of plasticizer, the flexibility of the foamed PVC is improved. Absorbability can be improved. In addition, metal soap etc. can be used as a surface treating agent, and the usage-amount is 0.5-5 weight% with respect to an inorganic filler, It is preferable to set it as 1-4 weight% especially.
[0025]
The blending amount of the filler is 160 to 500 parts with respect to 100 parts of the PVC. If it is less than 160 parts, the flow and sprayability during spray application will deteriorate. Moreover, when it exceeds 500 parts, the physical performance of a coating film will deteriorate and elasticity will fall.
[0026]
In the present invention, one or more phthalate ester plasticizers or benzoate ester plasticizers and one or more trimellitic ester plasticizers or polyester plasticizers are used as plasticizers. use.
[0027]
In this case, as the phthalate ester plasticizer, dibutyl phthalate (DBP), dihexyl phthalate (DHP), di-2-ethylhexyl phthalate (DOP), di-n-octyl phthalate (DnOP), diisooctyl phthalate (DIOP) ), Didecyl phthalate (DDP), dinonyl phthalate (DNP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), C₆~ C_TenMixed higher alcohol phthalate, butyl benzyl phthalate (BBP), octyl benzyl phthalate, nonyl benzyl phthalate, butyl phthal butyl glycolate (BPBG) and the like. Examples of the benzoate plasticizer include dipropylene glycol benzoate, N- Examples include butyl benzoate, 2,2,4-trimethyl-1,3-pentanediol isobutyrate benzoate, and 2,2,4-trimethyl-1,3-pentanediol dibenzoate. Trimellitic acid ester plasticizers include tri- (2-ethylhexyl) trimellitate (TOTM), tri-n-octyl trimellitate, triisodecyl trimellitate, triisooctyl trimellitate, and the like. . Polyester plasticizers include epoxidized double bonds of unsaturated fatty acid glycerides such as soybean oil with hydrogen peroxide or peracetic acid (ESBO), and epoxy compounds such as butyl or octyl alkyl oleates. A viscous low-polymerization polyester having an average molecular weight of about 500 to 8000, in which several to dozens of propylene glycol ester units of a dibasic acid such as adipic acid are connected in a straight chain. Adipic acid polyesters having an average molecular weight of 500 to 2200 and phthalic acid-based polyesters (oligoesters of phthalic acid and alkylene glycol, terminal alkanols, alkanes or alkenoic acid modified products) are suitable.
[0028]
As a plasticizer, in addition to the above, other plasticizers can be further blended. Other plasticizers include tricresyl phosphate (TCP), trioctyl phosphate (TOF), trixylenyl phosphate (TXP), monooctyl diphenyl phosphate, monobutyl-dixylenyl phosphate (BZX), etc. Phosphoric acid esters, phenolic alkyl sulfonic acid esters, dioctyl adipate (DOA), dioctyl azelate (DOZ), dioctyl sebacate (DOS) and other linear dibasic acid esters, 2,2,4-trimethyl -1,3-pentadiol mono or diisobutyrate, tributyl citrate ester, trioctyl acetyl citrate ester, C₆~ C_TenExamples include ester plasticizers other than the above, such as tri- or tetraethylene glycol esters of fatty acids, methylacetylricinoleate, nitrile synthetic rubbers, chlorinated products, and petroleum auxiliary plasticizers.
[0029]
The blending amount of the phthalate ester plasticizer or benzoate ester plasticizer is preferably 100 to 450 parts, particularly 150 to 350 parts, based on 100 parts of PVC. If the amount is less than 100 parts, the gelation rate of the PVC sol will be accelerated, the foam cell formation will be hindered and the foaming ratio will be lowered, the coating film hardness after baking will be hard, the impact absorption of foamed PVC will be lowered and soundproofing Performance may be reduced. On the other hand, if it exceeds 450 parts, the physical properties of the coated film after baking will be too soft, and the chipping resistance may not be ensured. In this case, the blending amount of the trimellitic acid ester plasticizer and the polyester plasticizer is 15 to 30 parts, particularly 20 to 25 with respect to 100 parts of the total amount of the phthalic acid ester plasticizer and the benzoic acid ester plasticizer. It is preferable to use these parts together in terms of blackout suitability, chipping resistance, and the appearance of the foamed PVC. When the blending amount of trimellitic acid plasticizer or polyester plasticizer is small, the effect is not sufficiently exhibited. When the blending amount is too large, chipping resistance is lowered, and physical properties of the foamed PVC are lowered. The total amount of phthalate ester plasticizer, benzoate ester plasticizer, trimellitic ester plasticizer, and polyester plasticizer is preferably not more than 500 parts per 100 parts of PVC.
[0030]
Furthermore, in the present invention, a low boiling point plasticizer having a boiling point of 150 to 250 ° C., for example, a petroleum hydrocarbon (paraffinic, naphthenic, aromatic) plasticizer, etc. is used if necessary for improving spray workability. Can be blended. The blending amount is 5 to 50 parts, preferably 5 to 40 parts, more preferably 10 to 30 parts per 100 parts of PVC. If it exceeds 50 parts, the low-boiling point plasticizer is volatilized at the time of baking, and there is a possibility that the foaming ratio is lowered, and cracks and abnormal foaming of the baking coating film occur.
[0031]
The undercoat agent of the present invention is a combination of polyamidoamine and blocked isocyanate used as an adhesion component, which can improve the adhesion of the foamed PVC coating to the substrate, and in particular, polyamidoamine and blocked isocyanate. When used together, water resistance and corrosion resistance are remarkably improved, and noise prevention is also remarkably improved. This is because polyamidoamine and blocked isocyanate are cross-linked and a urethane bond is generated, and the PVC coating film is given flexibility and elasticity, impact absorption is improved, and an excellent sound evaluation is given. Conceivable. The blending amount is preferably 5 to 40 parts, particularly 10 to 30 parts with respect to 100 parts of PVC. In this case, the polyamidoamine is 1 to 30 parts, particularly 5 to 20 parts with respect to 100 parts of PVC, and the blocked isocyanate is It is preferable that it is 1-35 parts with respect to 100 parts of PVC, especially 3-25 parts. If the amount of the adhesion component is less than 5 parts, the effect is not sufficiently exerted, and if it is more than 40 parts, the liquid viscosity of the PVC sol is increased and the spray workability may be lowered.
[0032]
In addition, the undercoat agent of the present invention has a hygroscopic agent such as calcium oxide and magnesium oxide that catches moisture in the sol and prevents foaming due to moisture, thereby improving the water resistance and corrosion resistance of the foamed PVC. 5 to 100 parts, particularly 10 to 40 parts can be blended with 100 parts of PVC. Note that the addition of this hygroscopic agent is particularly suitable because it does not cause the problem of blistering during inter-process standing. That is, for example, when the line stops on a soil or day holiday, and the undercoat agent before foaming may be swollen due to moisture absorption while it is applied wet, the addition of this moisture absorbent is suitable. is there.
[0033]
Furthermore, 0-5 parts, especially 0.1-3 parts can be blended with respect to 100 parts of PVC using PVC stabilizers such as dibutyltin laurate-based and zinc-based organic composites as a bubble regulator. In addition, pigments such as carbon black, titanium oxide, cadmium yellow, and phthalocyanine blue can be used as the colorant, and 0 to 5 parts, preferably 1 to 3 parts can be blended with 100 parts of PVC.
[0034]
In addition, it is preferable that the undercoat agent of the present invention foams at a foaming ratio of 1.2 to 1.6 times at 120 to 160 ° C. In this case, it is preferable that the time required for the expansion ratio to be 1.2 to 1.6 is 20 to 60 minutes. When the expansion ratio is lower than 1.2 times, the impact absorbability of the foamed PVC is lowered and the soundproofing performance is lowered. When the expansion ratio is higher than 1.6 times, the chipping resistance of the foamed PVC is lowered and the water resistance is also deteriorated. Moreover, the foaming temperature is lower than 120 ° C., and further, the foaming ratio that does not become 1.2 to 1.6 times at 120 to 160 ° C. is difficult to adapt to the painting process of automobiles.
[0035]
The undercoat agent of the present invention is particularly suitable as an undercoat for an automotive floor back or foil house panel, and the undercoat agent of the present invention is used for an automotive floor back or wheel house panel. In the case of forming an undercoat film, it is preferable to apply this undercoat agent to the panel and then heat to 120 to 160 ° C. to form a foamed PVC layer having a foaming ratio of 1.2 to 1.6 times. In this case, the thickness of the foamed PVC layer (film) is 1 to 4 mm, preferably 1.5 to 4 mm, and more preferably 2 to 4 mm. If it is thinner than 1 mm, the soundproofing performance may be deteriorated due to a decrease in chipping resistance and a decrease in shock absorption. On the other hand, if it is thicker than 4 mm, the coating amount increases, and there is a concern that the weight of the vehicle body increases, the coating workability decreases, and the vertical portion droops.
[0036]
According to the present invention, when non-foamed PVC is used, a film thickness of 6 mm or more is normally required in consideration of stone noise countermeasures. However, even if the undercoat film is thin as described above, sufficient noise prevention effect is obtained. Is demonstrated.
[0037]
The means for applying the undercoat agent to the panel is not particularly limited, but a spray application method is preferred, and therefore the undercoat agent of the present invention is preferably formed as a PVC foamed sol for spray application. In addition, it is recommended that the heating, foaming, and curing at 120 to 160 ° C. be performed simultaneously with the drying and baking processes of the intermediate coating and the top coating in the automobile coating process.
[0038]
In addition, as the undercoat method, there are a seal spray application performed for the purpose of waterproofing and dustproofing the panel joint and a surface spray application performed for the purpose of preventing rust and chipping on the general panel surface. Then, a seal spray coating is performed, and a surface spray coating is performed from above. Therefore, since both layers are applied in an overlapping manner, compatibility between the two layers before drying (at the time of application) and adhesion after drying are required. For this reason, the undercoat agent used for seal spray coating and surface spray coating is the same system. However, since the undercoat agent of the present invention can be applied to both seal spray coating and surface spray coating, it is excellent in terms of equipment and workability such as storage tank, piping, coating equipment, etc. Is. When the undercoat agent of the present invention is used for both seal blowing and surface blowing, it is preferable to perform surface blowing while the seal blowing surface is in a wet state, and foam and cure both at the same time. In addition, when used only as a surface spray coating, the undercoat agent of the present invention is a PVC system. Therefore, as an undercoat agent for seal spray coating, a PVC system is used in terms of compatibility and adhesion. It is preferable to use it.
[0039]
The undercoat agent of the present invention is a two-layer type in which the undercoat film of the two-layer structure is used as a cushion material for the lower layer, or used as a surface layer (upper layer), and further used in both upper and lower layers. However, it is preferably used as a single layer type.
[0040]
The undercoat agent of the present invention is excellent in chipping resistance and noise prevention effect even when it is a single layer, and also exhibits such an effect even when the undercoat film is thin as described above. You can fully enjoy the benefits of being good.
[0041]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following example, the test method for each performance is as follows. In the following examples, “wet” means a gel state coating film before foaming and curing.
[0042]
[Test method]
Stone honey noise reduction effect
A coating film having an area of 190 × 190 mm and a predetermined thickness is formed at the center of an electrodeposited steel plate of 1.6 × 300 × 300 mm, and this steel plate has an outer size of 300 × 300 mm, an inner size of 200 × 200 mm, and a thickness. The frame 1 is sandwiched between 20 mm steel square frames and is inclined at 45 ° as shown in FIGS. 1 and 2, and a vinyl chloride resin pipe 3 having an inner diameter of 25 mm and a length of 2 m above the coating film 2. Is arranged so that the steel ball falls in the center of the coating film 2. Then, steel balls having a diameter of 8 mm and a weight of 2.08 g are dropped from the pipe 3 one by one, and an impact sound generated when the steel ball collides with the coating film 2 is measured. In this case, the lower end position of the pipe 3 is 40 mm above the center of the coating film 2, and the microphone 4 that collects the impact sound is located 200 mm from the center of the coating film 2 and 40 mm away from the pipe 3. installed. The result is an average value of 8 measurements.
[0043]
In this case, the impact sound of the steel sheet without the coating film was 106 dB in terms of POA value (2.5 to 10 KHz), and the result was evaluated by how much the impact sound was reduced compared to this impact sound. .
[0044]
Chipping resistance
A sample was applied on a steel plate subjected to electrodeposition coating so that the wet film thickness was 1000 μm, and baked at 130 ° C. for 20 minutes.
The sample is set at an angle of 60 ° from the horizontal with the paint surface facing up, and the lower end of a 2 m long vinyl chloride pipe with an inner diameter of 20 mm is set up perpendicular to the coating surface. The M-4 nut defined in JIS was dropped through and the total weight of the nut until the substrate was exposed was measured.
[0045]
Foaming rate
The sample was applied on the electrodeposited steel sheet so that the wet thickness was 2 mm, and after baking under the prescribed conditions, the thickness after drying was measured, and the foaming ratio was calculated by the thickness ratio before and after baking. The foaming rate is displayed as, for example, 0%: no foaming, 50%: 1.5 times.
[0046]
Water resistance test
After the baked sample was treated for 10 days with warm water at 40 ° C., the chipping resistance test was performed on the sample that was allowed to stand at room temperature for 2 hours to obtain the chipping resistance after water resistance. In addition, evaluation of water resistance is the following formula
(Chip resistance after water resistance / initial chipping resistance) x 100 (%)
The higher the numerical value, the better the water resistance.
[0047]
Rust prevention
The electrodeposition coating plate was cut into a grid pattern with a pitch of 5 mm leading to the steel plate substrate, and then the sample was applied to 2 mm wet and baked at 130 ° C. for 20 minutes. Cut the surface of the sample after baking so that the film thickness after drying is 2 mm, put it in a salt spray tester for 10 days, remove it, peel off the coating, and rust at the grid-like cut part of the electrodeposition coated plate The presence or absence of occurrence was confirmed. Surface cutting is an intentional attempt to create a condition in which the foamed coating film is free of skin and to be in harsh conditions that are easy to absorb water.
[0048]
For comparison, the PVC material (non-foamed type) was wet cut at 1 mm and 1 mm after baking, and was compared with the above foamed PVC.
Evaluation criteria
Y: No abnormality
Δ: Some rust generated
×: Rust generation
[0049]
Blistering between processes
After applying the sample on the electrodeposited steel sheet to a thickness of 2 mm, leave it for 24 hours at 30 ° C x 80% humidity, take it out and bake at 140 ° C for 30 minutes, and check for abnormal foaming due to moisture absorption did.
Y: No abnormality
△: There is a little
×: blistering
[0050]
Blackout aptitude
A sample was applied on a steel plate subjected to electrodeposition coating to a thickness of 2 mm wet, and then baked at 140 ° C. for 30 minutes. Blackout was applied to the baking sample by spray coating at 20 to 40 μm, dried at room temperature for 2 hours, and then evaluated for stickiness of the painted surface by finger touch.
○: No stickiness
Δ: Sticky but not attached to fingers
×: Adhered to finger
[0051]
[Examples and comparative examples]
PVC sols having the formulations shown in Tables 1 and 2 were prepared and foamed at 130 ° C. for 20 minutes, and the performance shown in the same table was evaluated for the obtained foamed PVC. The results are also shown in the table.
[0052]
[Table 1]

[0053]
[Table 2]

* 1 Copolymer resin (vinyl chloride-vinyl acetate copolymer,
                        Vinyl acetate content 8% by weight, average polymerization degree 1900,
                        (Average particle size of 1 μm or less)
* 2 Dipropylene glycol benzoate
* 3 Adipic acid polyester, molecular weight 2000
* 4 Paraffinic hydrocarbon, boiling point 170 ° C
[0054]
From the results of Tables 1 and 2, the use of TOTM or polyester plasticizer in combination with DINP or benzoate plasticizer as plasticizer, and the use of polyamidoamine and blocked isocyanate improves blackout suitability and leaves the process feeling untouched. It was confirmed that a coating film having good water resistance and corrosion resistance and excellent noise prevention effect was formed.
[0055]
【The invention's effect】
According to the present invention, even when a blackout paint is applied on the formed coating film, there is no stickiness, and no blistering occurs even if the film is left in high humidity after being applied and baked. Moreover, it is possible to form a coating film having excellent chipping resistance, water resistance, and corrosion resistance and excellent noise prevention effect.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side view of a measuring device for effect of reducing a stone squeak noise.
FIG. 2 is a front view of the apparatus for measuring the effect of reducing stone sneak noise.
[Explanation of symbols]
1 frame
2 Coating film
3 Pipe
4 Microphone

Claims (4)

In a noise-preventing undercoat agent containing a vinyl chloride resin, an organic foaming agent, a filler, and a plasticizer, the above-mentioned plasticizer is a trimellit with respect to 100 parts by weight of a phthalate ester plasticizer or a benzoate ester plasticizer. An undercoat agent for noise prevention characterized by using 15 to 30 parts by weight of an acid ester plasticizer or a polyester plasticizer and blending blocked isocyanate and polyamidoamine as adhesive components. The undercoat agent according to claim 1, wherein a low boiling point plasticizer having a boiling point of 150 to 250 ° C is blended in the plasticizer. The undercoat agent according to claim 1 or 2, further comprising a hygroscopic agent. The undercoat agent according to any one of claims 1 to 3, wherein the undercoat agent is used for an undercoat on a floor back part or a wheel house part of an automobile.

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