JPS60229930A - Reinforcing material - Google Patents

Abstract

PURPOSE:A reinforcing material, consisting of a composition obtained by incorporating an epoxy resin with dicyandiamide as a curing agent and 3-(3,4-dichlrophenyl)-1,1-dimethylurea as a curing accelerator, and having high reactivity and reinforcing property and long pot life. CONSTITUTION:A reinforcing material, obtained by incorporating 100pts.wt. epoxy resin with >=5pts.wt. dicyandiamide of formula I, >=5pts.wt. 3-(3,4-dichlorophenyl)-1,1-dimethylurea of formula II and 10-400pts.wt. filler, e.g. talc or clay, as an optional component to give a composition suitable therefor, and consisting of the resultant composition. A reinforcing member, e.g. cloth woven from glass fibers or metal foil, is applied to or embedded in the resultant reinforcing material consisting of the above-mentioned composition to afford great reinforcing effect.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a reinforcing material having high reactivity, high reinforcing properties, and a long pot life, which is formed from a composition containing an epoxy resin as a main component.

(Conventional technology) Social M that aims to save resources and energy as has recently been the case.
Based on this, for example, panels such as automobile doors and fenders are being quantified and the thickness of the panels is being made thinner, but as a reaction to this, there is a problem that the tension and rigidity of the panels is reduced and quality is deteriorated.

・As a solution to this problem, for example,
As disclosed in Japanese Patent No. 3659, a proposal is to form a thermosetting resin composition such as an epoxy resin into a sheet shape and apply it locally to areas with weak rigidity, and then harden it with the heat of a coating furnace to create a reinforcing structure. is being done.

This method is a useful reinforcing method that can increase tension stiffness without increasing weight.

On the other hand, in order for reinforcing materials to be used in mass production sites such as automobiles, they must satisfy the following eight conditions.

(1) Long pot life - Can be self-adhesive after 14 days at 40°C (2) Cures quickly - Can be cured within 30 minutes at -140°C (3) Highly reinforcing properties ---Rigidity reinforcement rate is 8 times or more that of steel plate alone.

The above eight conditions will be explained in detail below.

Regarding pot life: After the reinforcing material is produced, it takes at most 8 to 4 months for it to be used at a mass production site.

During this period, it must be able to self-adhere to the steel plate without losing its tackiness. As a result of considering the high temperatures in summer, it is necessary to have a pot life of at least 14 days in a continuous atmosphere of 40°C. In other words, if it remains self-adhesive even after 14 days of continuous treatment at 40°C, it can be said to have a pot life of 3 to 4 months at room temperature, regardless of the season.

Regarding short-time curing: For automobiles, the reinforcement material is 140'
It is cured in a coating oven with a CXaO content setting. Therefore, in order to ensure the desired reinforcing properties, it is necessary to design the formulation so that it cures within 80 minutes at 140°C.

Regarding strength: The stiffness reinforcement rate for the reinforced material (for example, steel plate) alone is the criterion for evaluation. The required value varies depending on the application site, but according to the results of studies by the inventors, the stiffness reinforcement rate needs to be at least 8 times that of the reinforced material alone. Below this, the tension and rigidity will be low and the sticky feeling will not be resolved. Note that the stiffness reinforcement ratio is closely related to the thickness of the reinforcing material. In other words, the stiffness is proportional to the 8th power of the thickness, so the thicker it is, the higher the reinforcing effect will be. However, making the reinforcing material too thick is undesirable as it increases weight and cost, and it is preferable that the upper limit of the thickness be 4 mm. However, conventional reinforcing materials made of compositions containing epoxy resins react quickly and have high reinforcing properties, but have the drawback of short pot life. In other words, if it is stored at room temperature after production, it will gradually lose its self-adhesiveness, making it impossible to apply it to the reinforced material. On the other hand, the tackiness of the reinforcing material is due to the tackiness of the liquid epoxy resin, and the cause of the loss of tackiness is the reaction between the liquid epoxy resin and the curing agent.

(Object of the Invention) The present invention was made by focusing on the above-mentioned problems of the conventional art, and includes adding dicyanamide as a curing agent and 8-<8.4-dichlorophenyl)- as a curing accelerator to an epoxy resin. The purpose of this invention is to solve the above-mentioned problems by forming a reinforcing material with a composition containing 1,2-dimethylurea.

(Structure of the Invention) The reinforcing material of the present invention includes 5 parts by weight or more of dicyandiamide as a curing agent and 8-(8,4-dichlorophenyl)-1,1 as a curing accelerator based on 100 parts by weight of an epoxy resin.
- It is characterized by being formed from a composition containing 5 parts by weight or more of dimethylurea.

The above-mentioned dicyandiamide and 8"(8,4-dichlorophenyl)-1,1-dimethylurea have the following chemical structure, and the active hydrogen in the molecule reacts with the epoxy group of the epoxy resin to form a network structure. harden.

H2N-7-NH-G:N NH Dicyandiamide 8-(8,4-dichlorophenyl)-1,1-dimethylurea Any of the above components can be used alone as a curing agent, but both components do not cure. Temperature is 160-180
°C x 80 minutes, the reactivity is low, and it cannot be used alone. When both components are used together, the reactivity increases rapidly, and the desired reaction proceeds at 140°C for 80 minutes. The reason why the reaction temperature decreases in this way is said to be that both components react before reacting with the epoxy, producing derivatives of dimethylamine and dicyandiamide, and these reaction products react with the epoxy. The blending amount of both components is 5 parts by weight or more of dicyandiamide + 5 parts by weight or more of 8,4-dichlorophenyl)-1,1-dimethylurea per 100 parts by weight of the epoxy resin. If it is less than these crushes,
The stiffness reinforcement ratio is less than 8 times and has little effect. Also dicyandiamide and 8-(8,4-dichlorophenyl).

Even if -1,1-dimethylurea is added in an amount exceeding 10 parts by weight, no significant effect will be obtained.

The composition used to form the reinforcing material of the present invention may further contain other components in order to improve fluidity, cohesive force, and the like. For example, fillers such as talc, clay, calcium carbonate, asbestos, and carbon black can be added to prevent the reinforcing material from sagging or to color it. The blending amount of these fillers is not particularly limited, but is preferably in the range of 10 to 400 parts by weight per 100 parts by weight of the epoxy resin.

Further reinforcing effects can be obtained by attaching or embedding a reinforcing member such as cloth woven from glass fiber or metal foil to this reinforcing material.

(Example of the invention) This invention will be explained below with reference to Examples.

Example 1 In the formulation system shown in Table 1, liquid epoxy resin and curing agent were first mixed at a ratio of 1:1, passed through a three-roll mill 8 times to form a masterbatch, and the remaining liquid epoxy resin was added to this masterbatch. A composition having the ratio shown in Table 1 was prepared. Next, transfer this composition to a kneader (ffi 8!),
Solid epoxy resin with average particle size 4o~50μ and average particle size 8
Add ~4μ of talc in the amount shown in Table 1 and take the kneader container.
c and kneaded for 1 hour to obtain an epoxy resin composition.

Comparative example 112! An epoxy resin composition was prepared in the same manner as in Example 1 except that the curing agent and curing accelerator were changed as shown in Table 1.

The reactivity of each composition of Example 1 and Comparative Examples 1 and 2 was evaluated using a culastometer based on the gelation initiation temperature. As shown in Fig. 1, the obtained results showed that both curing agents were heated at 140''C.
The reactivity was high and the curability was good. However, in FIG. 1G, #i11 shows the results of Example 1, line 2 shows the results of Comparative Example 1, and line 8 shows the results of Comparative Example 2.

Table 1 Furthermore, the pot life was evaluated by the change in oral viscosity at 40°C, and the results shown in Figure 2 were obtained.

The compositions of Comparative Examples 1 (line 2) and 2 (line 2) using imidazole-based curing agents had a stiffness ratio of 4.
5 Comparative Example 2 has a good value of 4.8, but it is long and its usable life is limited to one week.

On the other hand, in the composition of the present invention (line 8), there is almost no change in viscosity even after two weeks, indicating that the composition has extremely low reactivity with the epoxy resin at 40°C and is stable. In this way, it satisfies the required characteristics of reinforcing materials. Further, the rigidity ratio described below is approximately 4.1, which is sufficient rigidity.

Example 2 In this example, the appropriate blending amounts of the curing agent dicyandiamide and the curing accelerator a-(L4 dic-p-ruphenyl)-1,,1-dimethylurea were investigated using the stiffness reinforcement rate of the reinforcing material as an evaluation point. First, the blending systems shown in Table 2 were kneaded in the same manner as in Example 1 to obtain 16 types of epoxy resin compositions.

Table 2 Comparative Example 8 x H:I-) 80 parts by weight of 828, Epicote 10
In addition to 120 parts by weight of 04 and 820 parts by weight of talc CTA, there were four types of compositions containing 6.10 and 20.80 parts by weight of D, P, and hardeners without dicyandiamide, and conversely, Epicote and talc. are the same, P.

Add 0.6° of dicyandiamide without hardener.
, 20.80 parts by weight were rolled in a press to form reinforcing materials with a thickness of 2. Cut these reinforcing materials with a cutter to a size of 25 m wide + 11 x length 140 ill, peel off the non-adhesive paper on one side, adhere to a 9.3 mm thick degreased steel plate of the same size, and heat it in the open at 140°C for 80 minutes.・It was cured and a bending test piece was prepared. These test pieces 1
As shown in Fig. 3, the steel plate was placed on a support base 2 of 1 = 100 trac with the reinforcing material facing down under the following conditions: Measuring temperature: 25°C Bending speed: 10 min/min to evaluate the rigidity. Figure 4 shows the results obtained by comparing the stiffness with the stiffness when alone and calculating the stiffness ratio.

In order to make the rigidity ratio 8 or more as shown in Fig. 4, 5 parts by weight or more of dicyandiamide is added to 100 parts by weight of the epoxy resin, P, Birdna (8-(3,4-dichlorophenyl) -1, It is necessary to use 35 parts by weight or more of 1-dimethylurea.

Note that as the amount of the curing agent dicyandiamide increases, the rigidity increases, but there is no significant difference at 1.0 PHR or more.

Next, among these compositions, especially the total amount of Epicoat 2
A composition in which 20 parts by weight of dicyandiamide, P, and hardener were added to 00 parts by weight (sample A), a composition in which 20 parts by weight of dicyandiamide alone was added (sample B),
For three types of compositions containing 20 parts by weight of D, P, and hardener (Sample C), the reactivity at 12°C'-140°C and 160°C was evaluated using a last meter to evaluate the gelation initiation temperature. , - The results obtained are shown in FIG.

In FIG. 5, line 1 shows the results for sample A, line 2 shows the results for sample 0, and line 8 shows the results for sample B, respectively.

From FIG. 5, it can be seen that the reactivity of the composition of the present invention (sample A) containing both P, hardener, and dicyandiamide is significantly superior to that of the compositions containing only P, hardener, and dicyandiamide (sample C, B). Ru.

Example 3 Six types of blending systems shown in Table 8 were kneaded in the same manner as in Example 1 to obtain epoxy resin compositions. The reactivity of each composition at 140°C was evaluated using a culastometer based on the gelation initiation temperature.

As shown in Table 8, the reaction of the yarn containing the dimer acid-modified epoxy resin, Epicoat 871 was slightly slower, but there was no practical problem and the reactivity was good in all cases. In addition, the rigidity ratio was high, and as shown in FIG. 6, the viscosity did not change for more than 14 days, indicating good storage stability. Lines 1 to 6 are the 8th
Each corresponds to Samples 1 to 6 in the table.

(Effects of the Invention) As explained above, the reinforcing material of the present invention is made from a composition in which a specific amount of dicyandiamide and 8-(a+4-dichlorophenyl)-1,1-dimethylurea are combined in an epoxy resin. Because of this formation, the effects of long pot life, high reactivity, and high reinforcing properties can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between test temperature and gelation start time for the compositions of Example 1 and Comparative Examples 1 and 2. Figure 2 is an explanatory diagram of changes in viscosity over time for the same compositions as in Figure 1. , FIG. 4 shows compositions 1 to 6 glues P in Comparative Example 8. A diagram showing the relationship between hardener amount and rigidity ratio, FIG. 5 is a diagram showing the relationship between test temperature and gelation start time for Samples A, B, and C of Example 2, and FIG. 6 is a diagram showing the relationship between each sample of Example 8. It is a diagram showing the relationship between the viscosity of a sample and the number of days that have passed. Figure 1 Test hot spring ('C) Figure 2 Figure 3 Figure 4 Figure 14 P, Hardener'j (pHR) Figure 5 Test hot spring ('C)

Claims (1)

[Claims] L: For 100 parts by weight of epoxy resin, 5 parts by weight or more of dicyandiamide as a curing agent and 8-8 parts as a curing accelerator.
A reinforcing material made of a composition containing 5 parts by weight or more of (8,4-dichlorophenyl)-1,1-dimethylurea.