JPH1180598A - Undercoat agent for noise prevention - Google Patents

Abstract

(57) Abstract: In a noise-preventing undercoating agent containing a vinyl chloride resin, an organic foaming agent, a plasticizer, and a filler, the vinyl chloride resin has an average particle size of 5 μm.
An undercoating agent for noise prevention, comprising at least 50% by weight of vinyl chloride resin particles comprising the following primary particles and secondary particles having an aggregate of the primary particles and having an average particle diameter of 100 μm or less. . The noise-prevention undercoat agent of the present invention has good spray workability, gives excellent chipping resistance and adhesion, and gives a coating film excellent in noise prevention.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise-preventing undercoat agent suitable as an undercoat for a place where noise due to rock splashes is to be prevented, such as a floor of an automobile or a panel of a wheel house.

[0002]

2. Description of the Related Art Frequently, rock and sand splashes are generated in the back of a car and in a wheel house (tire house) during driving, generating noise to the driver. I do.

[0003] Conventionally, as a method of preventing such rock and sand splashes, a non-foamed vinyl chloride resin (PV) has been applied to the back of the floor of an automobile or a panel of a wheel house.
C) A low-foaming vinyl chloride resin (PVC) paint having an expansion ratio of about 50% using a paint or an unexpanded balloon is used as an undercoat agent.

However, in the case of using the former non-foamed PVC, a thicker coating layer has an effect of reducing stone and sand noises, but increases costs and reduces work efficiency due to an increase in coating amount. As a result, the vehicle weight increases due to the increase in the application weight.

On the other hand, in the case of using the latter low-expansion type PVC paint using an unexpanded balloon, the soundproofing effect is increased by the effect of increasing the thickness of the coating layer as compared with the non-expanded PVC paint, but the unexpanded balloon is not used. Since the foam using the foam has a harder film than the foam using the foaming agent, the effect of absorbing a stone or sand is reduced, and the soundproofing effect is inferior. Further, the cushioning property is reduced by the balloon film, and the chipping resistance is extremely reduced. In this case, a compound that improves the physical properties of the compound (for example, low filling of an unexpanded balloon, vinyl chloride-
Although a certain level is ensured by using a vinyl acetate copolymer ratio, etc., it is still insufficient.

Further, in order to be used in an automobile manufacturing line, a heat resistance of 130 to 160 ° C. is required. Therefore, the material of the unexpanded balloon is made of acrylonitrile polymer having good heat resistance or acrylonitrile-vinylidene chloride copolymer. Those having a high acrylonitrile ratio are 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 health.

[0007] In view of the above, a foam type PVC paint using an organic foaming agent is desired. Particularly, when applied to the back floor of an automobile or a wheel house, it has excellent anti-noise properties and excellent chipping resistance. , Can form a coating film with good adhesion,
Further, from the viewpoint of workability, it is required to be excellent in sprayability.

[0008]

Means for Solving the Problems and Embodiments of the Invention The present invention has been made to meet the above-mentioned demands, and has an average primary particle diameter of 5 μm or less as a vinyl chloride resin. The above-mentioned object has been achieved by using a vinyl chloride-based resin in which parts are aggregated to mix primary particles with secondary particles, and combining this with an organic foaming agent, a filler, and a plasticizer.

That is, the present invention relates to a noise-preventing undercoating agent containing a vinyl chloride resin, an organic foaming agent, a plasticizer, and a filler, wherein the vinyl chloride resin has an average particle size of 5 μm or less. Provided is an undercoat agent for noise prevention, comprising at least 50% by weight of vinyl chloride resin particles composed of primary particles and secondary particles having an average particle diameter of 100 μm or less, which are aggregates of the primary particles. I do.

The undercoat agent of the present invention is used for forming an undercoat film on a place where noise due to stone splashes and sand splashes is to be prevented, such as a floor of an automobile or a panel of a wheel house. Even with a single layer, the noise can be effectively prevented, and can be incorporated into the current automobile painting process without changing the process.
In particular, in this coating step, a coating film excellent in spray workability, excellent in chipping resistance and adhesion, and excellent in noise prevention effect is provided.

[0011] Incidentally, a method of blending a plasticizer or a foaming agent with a vinyl chloride resin and foaming by heating is disclosed in JP-A-1-287147, JP-B-6-18916, and JP-A-7-330937. This is a known technique. However, there is no undercoating agent used in car floors, tire houses, etc. aimed at chipping resistance and noise prevention by stone splash. The undercoat agent of the present invention, which uses the specific amount of the agent, filler, and plasticizer and has the conditions to be applied to the current automobile manufacturing line, and also has excellent effects such as improved workability, storage stability, and soundproofing effect. Were found for the first time by the present inventors.

Hereinafter, the present invention will be described in more detail.
The noise-prevention undercoat agent of the present invention comprises a vinyl chloride resin as a base polymer, an organic foaming agent, a foaming aid, if necessary, a filler, and a plasticizer. It contains a moisture absorbent, a stabilizer, a colorant, and the like.

Here, the vinyl chloride resin (PVC) is a homopolymer of vinyl chloride, mainly composed of vinyl chloride, and a copolymer thereof with another copolymerizable monomer such as vinyl acetate (vinyl chloride content). 50% by weight or more, especially 70% by weight or more) can be used alone or in combination of two or more.

In this case, as PVC, the average particle size of the primary particles is 5 μm or less, preferably 3 μm or less, and more preferably 1.5 μm or less. Use mixed ones. Here, the use of PVC having a primary particle having an average particle diameter of more than 5 μm having a large particle diameter lowers chipping resistance and causes abnormal foaming on the foamed surface, which is not preferable in appearance.

The above PVC is obtained by aggregating a part of primary particles having a small particle diameter in a manufacturing process to obtain secondary particles, and is obtained by aggregating primary particles having a small particle diameter and a part thereof. Mixed secondary particles, the primary particle side and the secondary particle
And two peaks each having a different average particle size from each other.
Are mixed. In the PVC, the peak on the secondary particle side is preferably 100 μm or less, more preferably 3 to 30 μm, and particularly preferably 5 to 20 μm. When the average particle size exceeds 100 μm, the particle size becomes coarse, and when the polyvinyl chloride paste sol is applied by spraying, chips are liable to be clogged, the workability is reduced, and the surface state of the coated material lacks smoothness. And the appearance of seizure becomes poor, which is not preferable. The proportion of the secondary particles in the PVC is 20 to 90% by weight, particularly 40 to 8% by weight.
It is preferably 0% by weight. As such a PVC, for example, a commercially available product manufactured by Huls is available.
-7031 or the like can be used.

PVC in which the above primary particles and secondary particles are mixed
Has good swelling gelling property, workability and foam P
It is preferable from the viewpoint of the physical properties of VC. That is, the workability of spraying the PVC sol is improved (thixotropic property is improved).
Therefore, when blending a large particle size PVC with a small particle size PVC, a relatively large number of particles having a particle size between these large and small particle sizes are scattered in the blend, and thus, the Viscosity reduction is inhibited, and thixotropic properties decrease. On the other hand, PVC in which secondary particles are mixed by aggregating a part of primary particles having a small particle diameter has a small number of particles having an intermediate particle diameter. Is shown. Therefore,
In the case of spray application, high shear area 10000 sec ^-1
The coated material which gives good sprayability at 40,000 sec ^-1 ) and which is not in a sheared state after spraying has a high viscosity, has no sagging phenomenon, and maintains its shape in a vertical portion or the like.
In other words, regarding the gelling property, since the secondary particles are originally an aggregate (aggregate) of the primary particles, the performance of the primary particles is obtained, the swelling gelling property is good, and the storage stability is high. Second, since the secondary particles are strong aggregates, swelling with the plasticizer during storage of the sol before heating is prevented, and storage stability is good.

Further, PVC has an average degree of polymerization of 25.
00 or less, preferably 2000 or less, more preferably 1 or less.
Desirable is 900 or less. If the average polymerization degree is too high, the physical properties of the foamed PVC such as chipping resistance may be reduced. The lower limit of the average degree of polymerization is usually 50.
0, preferably 850, more preferably 1000.

As the above copolymer, a vinyl chloride-vinyl acetate copolymer is preferably used from the viewpoint of swelling and gelling properties. In this vinyl chloride-vinyl acetate copolymer, the vinyl acetate content is 1 to 15% by weight, especially 3 to 1
0% by weight is preferred. In this case, the vinyl chloride homopolymer has slightly lower adhesion on the metal surface than the vinyl chloride-vinyl acetate copolymer, while the vinyl chloride-vinyl acetate copolymer has a good swelling gelling property with respect to the plasticizer, and the adhesion by heating. Although good, the cost is high, so it is preferable to use both. The combination ratio is appropriately selected, but it is preferable that vinyl chloride homopolymer: vinyl chloride-vinyl acetate copolymer = 4: 1 to 1: 4 (weight ratio).

Further, as a copolymer, -CH ₂ ROH
Crosslinkable copolymers with groups can also be used. This is because the OH group reacts with a blocked isocyanate as an adhesion component described later at the time of heating to generate a urethane bond, thereby improving adhesion and water resistance.

In the present invention, PVC in which secondary particles are mixed with primary particles may be used alone, but if necessary, ordinary PVC can be used in combination, particularly from the viewpoint of noise prevention effect. . In this case, the proportion is 50% by weight or more, especially 7%, of the former PVC in which primary particles and secondary particles are mixed.
It is preferably 0% by weight, and if it is less than 50% by weight, spray workability is reduced.

Next, in the present invention, the organic foaming agent used for foaming PVC is not particularly limited, but the foaming agent having a decomposition temperature of 130 to 180 ° C. is used in that the existing coating process is not changed. Alternatively, it is preferable to use a foaming agent mixture or a mixture of a foaming agent and a foaming aid. If the decomposition temperature exceeds 180 ° C,
Does not foam well at a temperature of 60 ° C, while 130 ° C
If the decomposition temperature is lower, outgassing occurs before the PVC is cured, so that good foamed PVC cannot be obtained and storage stability may be poor.

Specifically, 4,4'-oxybis (benzenesulfonyl hydrazide (OBSH) is used as a foaming agent.
Can be preferably used, p-toluenesulfonyl azide, p-toluenesulfonyl azide
-Methylurethanebenzenesulfonyl hydrazide and the like can also be used. Further, as the foaming agent mixture, a mixture of OBSH and azodicarbonamide (ADCA) and the like can be preferably mentioned. Furthermore, the decomposition temperature alone is 180 ° C. like ADCA.
However, those having a decomposition temperature adjusted to 130 to 180 ° C. by being used in combination with a foaming aid can also be suitably used. Note that the decomposition temperature of OBSH or the like is 130 to 1
Even if a foaming aid is used in combination with a foaming agent or a foaming agent mixture at a temperature in the range of 80 ° C, as long as its decomposition temperature is in the range of 130 to 180 ° C.

Known foaming assistants can be used, and examples thereof include various metal oxides (eg, zinc oxide, magnesium oxide, etc.), metal soaps (eg, zinc stearate), urea compounds, amines and the like. . In addition, such a foaming auxiliary can be simultaneously compounded for another purpose. For example, metal soap is used as a surface treatment agent for inorganic fillers such as calcium carbonate. Metal soap used as such a surface treatment agent also has a foaming aid referred to here as long as it lowers the decomposition temperature of the foaming agent. Contained in the agent.

The compounding amount of the above-mentioned organic foaming agent is
The amount is preferably 1 to 3 parts, more preferably 1 to 2.5 parts, particularly preferably 1.5 to 2.5 parts, of the foaming agent or the foaming agent mixture with respect to 00 parts (parts by weight, hereinafter the same). Agent 0-1
5 parts, especially 1 to 10 parts.

In the present invention, examples of the filler include calcium carbonate, barium sulfate, clay, diatomaceous earth, silica, talc, and the like. One of these can be used alone, or two or more can be used in combination. If necessary, hollow particles such as glass balloons and resin balloons can be blended.

In this case, it is particularly preferable to use a surface-treated inorganic filler such as surface-treated calcium carbonate, and the average particle size of the inorganic filler is 0.01 to 1 μm, particularly 0.02 to 0.1 μm. and specific surface area by BET method of 5 to 30 m ² / g, in particular those 15~25m ² / g preferred. By using a surface-treated filler of fine particles and not adding a coarse filler, uniform dispersion in a PVC paste is measured, and the foam cell can be made dense. In addition, by using a surface-treated inorganic filler having a high specific surface area, a large amount of a plasticizer is added without any trouble, and the flexibility of the foamed PVC is improved by increasing the amount of the plasticizer.
It is possible to improve the shock absorbing property at the time of stone splash. In addition, metal soap etc. can be used as a surface treatment agent, and the amount of use is 0.5 to 5 with respect to an inorganic filler.
% By weight, particularly preferably 1 to 4% by weight.

The amount of the filler is preferably 160 to 500 parts based on 100 parts of the PVC. If the amount is less than 160 parts, the flow during spray coating and the dischargeability may be deteriorated. If the amount is more than 500 parts, the physical properties of the coating film may be deteriorated and the elasticity may be reduced.

In the present invention, it is preferable to use an aromatic plasticizer as the plasticizer. As such an aromatic plasticizer, dibutyl phthalate (DB)
P), dihexyl phthalate (DHP), di-2-ethylhexyl phthalate (DOP), di-n-octyl phthalate (DnOP), diisooctyl phthalate (D
IOP), didecyl phthalate (DDP), dinonyl phthalate (DNP), diisononyl phthalate (DIN)
P), diisodecyl phthalate (DIDP), C ₆ ~C
₁₀ Mixed higher alcohol phthalates, butyl benzyl phthalate (BBP), octyl benzyl phthalate, nonyl benzyl phthalate, phthalic acid esters such as butyl phthal butyl glycolate (BPBG), tricresyl phosphate (TCP), trixylenyl phosphate ( TXP), monooctyl diphenyl phosphate, monobutyl-dixylenyl phosphate (BZ-
X) and other phosphoric esters, dipropylene glycol benzoate, N-butyl benzoate, 2,2,4-trimethyl-1,3-pentanediol isobutyrate benzoate, 2,2,4-trimethyl-1,3- Benzoic acid esters such as pentanediol dibenzoate, phenolic alkylsulfonic acid esters and the like can be mentioned, and one of these can be used alone or in combination of two or more. Acid esters, particularly dialkyl phthalate and alkylbenzyl phthalate, and benzoic acid esters are preferably used.

Other plasticizers such as dioctyl adipate (DOA), dioctyl azelate (DOZ),
Linear dibasic acid esters such as dioctyl sebacate (DOS), phosphoric acid esters such as trioctyl phosphate (TOF), 2,2,4-trimethyl-1,3-pentadiol mono- or diisobutyrate, and tributyl citric acid esters, trioctyl acetyl citrate esters, tri- or tetraethylene glycol esters of C ₆ -C ₁₀ fatty acid, ester plasticizer other than the above, such as methyl acetyl ricinoleate, nitrile synthetic rubber, chlorinated and petroleum auxiliary A plasticizer or the like, or a mixture thereof can also be used.

In the present invention, a low-boiling plasticizer having a boiling point of 150 to 250 ° C. from the viewpoint of improving spray workability, etc.
For example, it is preferable to add a petroleum hydrocarbon (paraffinic, naphthenic, aromatic) plasticizer or the like. The compounding amount is preferably 5 to 50 parts, more preferably 5 to 40 parts, and still more preferably 10 to 30 parts with respect to 100 parts of PVC. If the amount is more than 50 parts, the low-boiling-point plasticizer volatilizes during baking, and the foaming ratio may be reduced, and cracks or abnormal foaming of the baked coating film may occur.

The total amount of the plasticizer, including the aromatic plasticizer and the low boiling plasticizer, is 180 to 100 parts by weight of PVC.
500 parts, preferably 180 to 300
Part. If less than 180 parts, PV
The gelation rate of the C sol is increased, which hinders the formation of foam cells and lowers the expansion ratio, and also increases the hardness of the coating film after baking, which may reduce the shock absorption of the foamed PVC and reduce the soundproofing performance. is there. On the other hand, if it is more than 500 parts, the physical properties of the coated film after baking are too soft, and it may not be possible to ensure chipping resistance.

In the undercoat agent of the present invention, it is preferable to use a polyamidoamine or a blocked isocyanate alone or in combination as an adhesive component from the viewpoint of improving the adhesion of the foamed PVC coating film to the substrate. When used in combination with a blocked isocyanate, water resistance and corrosion resistance are remarkably improved, and noise prevention is also remarkably improved. This is because the polyamidoamine and the blocked isocyanate are crosslinked to form a urethane bond, which imparts flexibility and elasticity to the PVC coating film, improves shock absorption, and provides excellent effects in sound evaluation. Conceivable. The amount is 5 to 100 parts of PVC.
It is preferably 40 parts, particularly 10 to 30 parts, in which case the polyamidoamine is 0 to 100 parts of PVC.
30 parts, especially 5 to 20 parts, the blocked isocyanate is P
The amount is preferably 1 to 35 parts, particularly 3 to 25 parts, per 100 parts of VC. If the amount of the adhesion component is less than 5 parts, the effect is not sufficiently exhibited.
The C sol may have an increased liquid viscosity, which may lower spray workability.

Further, the undercoat agent of the present invention includes a moisture absorbent such as calcium oxide or magnesium oxide that catches moisture in the sol to prevent foaming due to the moisture, and
PVC100 from the viewpoint of improving the water resistance and corrosion resistance of C
5 to 100 parts, especially 10 to 40 parts can be compounded per part. The addition of the hygroscopic agent is preferable because it does not particularly cause the problem of blistering during standing between processes. That is, for example, when the line stops on a soil, a holiday on a day, etc., and the undercoat agent before foaming may be blistered due to moisture absorption while being applied wet,
The addition of this hygroscopic agent is preferred.

Further, a PVC stabilizer such as a dibutyltin laurate-based or zinc-based organic composite agent is used as a foam control agent.
0 to 5 parts, especially 0.1 to 3 parts can be blended with 100 parts. In addition, pigments such as carbon black, titanium oxide, cadmium yellow, and phthalocyanine blue can be used as a coloring agent, and 0 to 5 parts, preferably 1 to 3 parts can be blended with 100 parts of PVC.

The undercoat agent of the present invention is particularly suitable for use as an undercoat for panels in the floor of the floor of an automobile or in a wheel house. Using the undercoat agent of the present invention, the undercoat in a floor of an automobile or in a wheel house. When an undercoat film is formed on the panel, the undercoat agent is spray-coated on the panel,
C. to form a foamed PVC layer. In this case, the thickness of the foamed PVC layer (film) is preferably 1 to 4 mm, preferably 1.5 to 4 mm, and more preferably 2 to 4 mm. If the thickness is less than 1 mm, there is a possibility that the soundproof performance may be reduced 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 amount of application increases, and there is a concern that the weight of the vehicle body increases, the application workability decreases, and the vertical portion sags.

According to the present invention, when non-foamed PVC is used, a film thickness of 6 mm or more is generally required in consideration of the stone splash noise countermeasure. The noise prevention effect is exhibited.

It is recommended that heating, foaming and curing be performed simultaneously with the drying and baking steps of the intermediate coating and the top coating in the coating process of the automobile.

As the undercoating method, there are a seal spray coating applied for the purpose of waterproofing and dustproofing to the panel joint portion, and a surface spraying application performed for the purpose of rust prevention and chipping resistance on the general surface of the panel. Usually, seal spray application is first performed, and surface spray application 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 coating) and adhesion after drying are required. Therefore, 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 face spray coating, the storage tank, piping,
It is excellent in equipment and workability such as coating equipment. In the case where the undercoat agent of the present invention is used for both seal blowing and surface blowing, it is preferable that surface blowing is performed while the seal blown surface is in a wet state, and both are foamed and cured simultaneously. In addition, when used only for face spray coating, the undercoat agent of the present invention is a PVC-based undercoat agent. Therefore, as the undercoat agent for seal spray coating, a PVC-based undercoat agent is used in terms of compatibility and adhesion. Preferably, it is used.

The undercoat agent of the present invention may be used in a two-layer undercoat film, such as a method for forming a lower cushion material, a method for using it as a surface layer (upper layer), or a method for use in both upper and lower layers. Although it can be applied to a two-layer type, it is preferably used as a single-layer type.

The undercoat agent of the present invention is excellent in chipping resistance and noise prevention effect even when a single layer is used, and exhibits the same effect even when the undercoat film is thin as described above. The advantage of good workability can be fully enjoyed.

[0041]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In addition, in the following examples, the test method of each performance is as follows. In the following examples, “wet” means a coating film in a gel state before foaming and curing.

[Test Method] A sample having a wet film thickness of 1 m was placed on a steel plate coated with chipping resistant electrodeposition coating.
m and baked at 130 ° C. for 20 minutes.
The above sample was set at an angle of 60 ° from horizontal with the coated surface facing up. The lower end of a 2m long vinyl chloride pipe with an inner diameter of 20mm and erected perpendicular to the coated surface was placed inside the pipe from the upper end of the pipe. Through which the M-4 nut specified by JIS was dropped, and the total weight of the nut until the substrate was exposed was measured.

[0043] The sample was applied to wet 1mm on steel plate subjected to adhesion electrodeposition coating was baked 130 ° C. × 20 min. Make a cut in the baked sample with a cutter knife, peel off from the end with nails,
The quality of adhesion was determined by the degree of peeling. ：: Cohesive failure △: Mixed agglomeration / interface destruction ×: Interfacial destruction

Stone splash noise reduction effect A coating film of a predetermined thickness is formed in an area of 190 × 190 mm on the central part of the 1.6 × 300 × 300 mm electrodeposited steel sheet. Inner dimensions 20
0x200mm, sandwiched by a 20mm thick steel square frame,
The frame 1 is arranged at an angle of 45 ° as shown in FIGS. 1 and 2, and a pipe 3 made of a vinyl chloride resin having an inner diameter of 25 mm and a length of 2 m is placed above the coating 2 with a steel ball in the center of the coating 2. Arrange so that it falls. 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 balls collide with the coating film 2 is measured. In this case, the lower end position of the pipe 3 is set at 40 mm above the center of the coating film 2, and the microphone 4 that collects the impact sound is located 20 mm from the center of the coating film 2.
It was installed at a position 0 mm above and 40 mm apart from the pipe 3. The results are average values of eight measurements.

In this case, the impact noise of the steel sheet having no coating film was 106 A at a POA value (2.5 to 10 KHz value).
dB, and the result was evaluated by how much the impact sound was reduced compared to the impact sound.

Spray workability On an electrodeposited steel plate, using an airless spray pump (compression ratio: 45: 1) and a 3/8 inch × 5 m hose, at a temperature of 30 ° C. and a static pressure of 100 kgf / c at the gun source.
Each sample was applied under the conditions of m ² , a gun distance of 300 mm, and a tip # 443 (manufactured by Nippon Gray Co., Ltd.), and the pattern width was measured to determine the spraying workability. ：: Pattern width of 200 mm or more △: Pattern width of 150 to 200 mm ×: 150 mm or less

[Examples and Comparative Examples]
C sol is prepared and foamed at 130 ° C for 20 minutes.
The chipping resistance, sound evaluation, and adhesion were evaluated according to the type of the resin, and the spray workability of the PVC sol was evaluated. The results are shown in the same table.

[0048]

[Table 1] * 1 Paste PVC: paste polyvinyl chloride, average degree of polymerization 1200, average particle size 1 μm or less (particle size distribution has two peaks Peak: primary particle size 0.1 μm, secondary particle size 12 μm) [manufactured by Huls ( * 2 Paste PVC: Paste polyvinyl chloride, average degree of polymerization 1600, average particle size 2 μm (particle size distribution has one peak) * 3 Paste PVC: Paste polyvinyl chloride, Average polymerization degree 2000, average particle diameter 1 μm (particle size distribution has one peak) * 4 Paste PVC: paste polyvinyl chloride, average polymerization degree 1000, average particle diameter 20 μm (particle size distribution has one peak) * 5 Copolymer resin: vinyl chloride / vinyl acetate copolymer (vinyl acetate content 8% by weight), average degree of polymerization 190
0, average particle size 1 μm or less (particle size distribution has two peaks Peak: primary particle size 1 μm, secondary particle size 10 μm) * 6 Copolymer resin: vinyl chloride / vinyl acetate copolymer (vinyl acetate content 5% by weight), Average polymerization degree 160
0, average particle size 2 μm (particle size distribution has one peak) * 7 Copolymer resin: vinyl chloride / vinyl acetate copolymer (vinyl acetate content 11% by weight), average degree of polymerization 100
0, average particle size 20 μm (particle size distribution has one peak) * 8 Low boiling plasticizer: paraffinic hydrocarbon, boiling point 170
° C

From the results shown in Table 1, when a vinyl chloride resin in which primary particles and secondary particles are mixed is used, the chipping resistance is excellent, the sound evaluation and the adhesion are good, and
It is recognized that the spray workability is excellent.

[0050]

The undercoat agent for noise prevention according to the present invention has good spray workability, gives excellent chipping resistance and adhesion, and gives a coating film having excellent noise prevention.

[Brief description of the drawings]

FIG. 1 is a side view of an apparatus for measuring the effect of reducing rock flies.

FIG. 2 is a front view of the rock popping noise reduction effect measuring device.

[Explanation of symbols]

 1 frame 2 coating film 3 pipe 4 microphone

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yutaka Ohashi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (1)

[Claims] 1. A noise-preventing undercoating agent containing a vinyl chloride resin, an organic foaming agent, a plasticizer, and a filler, wherein the vinyl chloride resin has an average particle size of 5 μm.
An undercoating agent for noise prevention, comprising at least 50% by weight of vinyl chloride resin particles comprising the following primary particles and secondary particles having an aggregate of the primary particles and having an average particle diameter of 100 μm or less. .